text: // SPDX-License-Identifier: GPL-2.0-or-later
  /*
   *      NET3    Protocol independent device support routines.
   *
   *	Derived from the non IP parts of dev.c 1.0.19
   *              Authors:	Ross Biro
   *				Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
   *				Mark Evans, <evansmp@uhura.aston.ac.uk>
   *
   *	Additional Authors:
   *		Florian la Roche <rzsfl@rz.uni-sb.de>
   *		Alan Cox <gw4pts@gw4pts.ampr.org>
   *		David Hinds <dahinds@users.sourceforge.net>
   *		Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>
   *		Adam Sulmicki <adam@cfar.umd.edu>
   *              Pekka Riikonen <priikone@poesidon.pspt.fi>
   *
   *	Changes:
   *              D.J. Barrow     :       Fixed bug where dev->refcnt gets set
   *                                      to 2 if register_netdev gets called
   *                                      before net_dev_init & also removed a
   *                                      few lines of code in the process.
   *		Alan Cox	:	device private ioctl copies fields back.
   *		Alan Cox	:	Transmit queue code does relevant
   *					stunts to keep the queue safe.
   *		Alan Cox	:	Fixed double lock.
   *		Alan Cox	:	Fixed promisc NULL pointer trap
   *		????????	:	Support the full private ioctl range
   *		Alan Cox	:	Moved ioctl permission check into
   *					drivers
   *		Tim Kordas	:	SIOCADDMULTI/SIOCDELMULTI
   *		Alan Cox	:	100 backlog just doesn't cut it when
   *					you start doing multicast video 8)
   *		Alan Cox	:	Rewrote net_bh and list manager.
   *              Alan Cox        :       Fix ETH_P_ALL echoback lengths.
   *		Alan Cox	:	Took out transmit every packet pass
   *					Saved a few bytes in the ioctl handler
   *		Alan Cox	:	Network driver sets packet type before
   *					calling netif_rx. Saves a function
   *					call a packet.
   *		Alan Cox	:	Hashed net_bh()
   *		Richard Kooijman:	Timestamp fixes.
   *		Alan Cox	:	Wrong field in SIOCGIFDSTADDR
   *		Alan Cox	:	Device lock protection.
   *              Alan Cox        :       Fixed nasty side effect of device close
   *					changes.
   *		Rudi Cilibrasi	:	Pass the right thing to
   *					set_mac_address()
   *		Dave Miller	:	32bit quantity for the device lock to
   *					make it work out on a Sparc.
   *		Bjorn Ekwall	:	Added KERNELD hack.
   *		Alan Cox	:	Cleaned up the backlog initialise.
   *		Craig Metz	:	SIOCGIFCONF fix if space for under
   *					1 device.
   *	    Thomas Bogendoerfer :	Return ENODEV for dev_open, if there
   *					is no device open function.
   *		Andi Kleen	:	Fix error reporting for SIOCGIFCONF
   *	    Michael Chastain	:	Fix signed/unsigned for SIOCGIFCONF
   *		Cyrus Durgin	:	Cleaned for KMOD
   *		Adam Sulmicki   :	Bug Fix : Network Device Unload
   *					A network device unload needs to purge
   *					the backlog queue.
   *	Paul Rusty Russell	:	SIOCSIFNAME
   *              Pekka Riikonen  :	Netdev boot-time settings code
   *              Andrew Morton   :       Make unregister_netdevice wait
   *                                      indefinitely on dev->refcnt
   *              J Hadi Salim    :       - Backlog queue sampling
   *				        - netif_rx() feedback
   */
  
  #include <linux/uaccess.h>
  #include <linux/bitops.h>
  #include <linux/capability.h>
  #include <linux/cpu.h>
  #include <linux/types.h>
  #include <linux/kernel.h>
  #include <linux/hash.h>
  #include <linux/slab.h>
  #include <linux/sched.h>
  #include <linux/sched/mm.h>
  #include <linux/mutex.h>
  #include <linux/rwsem.h>
  #include <linux/string.h>
  #include <linux/mm.h>
  #include <linux/socket.h>
  #include <linux/sockios.h>
  #include <linux/errno.h>
  #include <linux/interrupt.h>
  #include <linux/if_ether.h>
  #include <linux/netdevice.h>
  #include <linux/etherdevice.h>
  #include <linux/ethtool.h>
  #include <linux/skbuff.h>
  #include <linux/bpf.h>
  #include <linux/bpf_trace.h>
  #include <net/net_namespace.h>
  #include <net/sock.h>
  #include <net/busy_poll.h>
  #include <linux/rtnetlink.h>
  #include <linux/stat.h>
  #include <net/dst.h>
  #include <net/dst_metadata.h>
  #include <net/pkt_sched.h>
  #include <net/pkt_cls.h>
  #include <net/checksum.h>
  #include <net/xfrm.h>
  #include <linux/highmem.h>
  #include <linux/init.h>
  #include <linux/module.h>
  #include <linux/netpoll.h>
  #include <linux/rcupdate.h>
  #include <linux/delay.h>
  #include <net/iw_handler.h>
  #include <asm/current.h>
  #include <linux/audit.h>
  #include <linux/dmaengine.h>
  #include <linux/err.h>
  #include <linux/ctype.h>
  #include <linux/if_arp.h>
  #include <linux/if_vlan.h>
  #include <linux/ip.h>
  #include <net/ip.h>
  #include <net/mpls.h>
  #include <linux/ipv6.h>
  #include <linux/in.h>
  #include <linux/jhash.h>
  #include <linux/random.h>
  #include <trace/events/napi.h>
  #include <trace/events/net.h>
  #include <trace/events/skb.h>
  #include <linux/inetdevice.h>
  #include <linux/cpu_rmap.h>
  #include <linux/static_key.h>
  #include <linux/hashtable.h>
  #include <linux/vmalloc.h>
  #include <linux/if_macvlan.h>
  #include <linux/errqueue.h>
  #include <linux/hrtimer.h>
  #include <linux/netfilter_ingress.h>
  #include <linux/crash_dump.h>
  #include <linux/sctp.h>
  #include <net/udp_tunnel.h>
  #include <linux/net_namespace.h>
  #include <linux/indirect_call_wrapper.h>
  #include <net/devlink.h>
  
  #include "net-sysfs.h"
  
  #define MAX_GRO_SKBS 8
  
  /* This should be increased if a protocol with a bigger head is added. */
  #define GRO_MAX_HEAD (MAX_HEADER + 128)
  
  static DEFINE_SPINLOCK(ptype_lock);
  static DEFINE_SPINLOCK(offload_lock);
  struct list_head ptype_base[PTYPE_HASH_SIZE] __read_mostly;
  struct list_head ptype_all __read_mostly;	/* Taps */
  static struct list_head offload_base __read_mostly;
  
  static int netif_rx_internal(struct sk_buff *skb);
  static int call_netdevice_notifiers_info(unsigned long val,
  					 struct netdev_notifier_info *info);
  static int call_netdevice_notifiers_extack(unsigned long val,
  					   struct net_device *dev,
  					   struct netlink_ext_ack *extack);
  static struct napi_struct *napi_by_id(unsigned int napi_id);
  
  /*
   * The @dev_base_head list is protected by @dev_base_lock and the rtnl
   * semaphore.
   *
   * Pure readers hold dev_base_lock for reading, or rcu_read_lock()
   *
   * Writers must hold the rtnl semaphore while they loop through the
   * dev_base_head list, and hold dev_base_lock for writing when they do the
   * actual updates.  This allows pure readers to access the list even
   * while a writer is preparing to update it.
   *
   * To put it another way, dev_base_lock is held for writing only to
   * protect against pure readers; the rtnl semaphore provides the
   * protection against other writers.
   *
   * See, for example usages, register_netdevice() and
   * unregister_netdevice(), which must be called with the rtnl
   * semaphore held.
   */
  DEFINE_RWLOCK(dev_base_lock);
  EXPORT_SYMBOL(dev_base_lock);
  
  static DEFINE_MUTEX(ifalias_mutex);
  
  /* protects napi_hash addition/deletion and napi_gen_id */
  static DEFINE_SPINLOCK(napi_hash_lock);
  
  static unsigned int napi_gen_id = NR_CPUS;
  static DEFINE_READ_MOSTLY_HASHTABLE(napi_hash, 8);
  
  static DECLARE_RWSEM(devnet_rename_sem);
  
  static inline void dev_base_seq_inc(struct net *net)
  {
  	while (++net->dev_base_seq == 0)
  		;
  }
  
  static inline struct hlist_head *dev_name_hash(struct net *net, const char *name)
  {
  	unsigned int hash = full_name_hash(net, name, strnlen(name, IFNAMSIZ));
  
  	return &net->dev_name_head[hash_32(hash, NETDEV_HASHBITS)];
  }
  
  static inline struct hlist_head *dev_index_hash(struct net *net, int ifindex)
  {
  	return &net->dev_index_head[ifindex & (NETDEV_HASHENTRIES - 1)];
  }
  
  static inline void rps_lock(struct softnet_data *sd)
  {
  #ifdef CONFIG_RPS
  	spin_lock(&sd->input_pkt_queue.lock);
  #endif
  }
  
  static inline void rps_unlock(struct softnet_data *sd)
  {
  #ifdef CONFIG_RPS
  	spin_unlock(&sd->input_pkt_queue.lock);
  #endif
  }
  
  /* Device list insertion */
  static void list_netdevice(struct net_device *dev)
  {
  	struct net *net = dev_net(dev);
  
  	ASSERT_RTNL();
  
  	write_lock_bh(&dev_base_lock);
  	list_add_tail_rcu(&dev->dev_list, &net->dev_base_head);
  	hlist_add_head_rcu(&dev->name_hlist, dev_name_hash(net, dev->name));
  	hlist_add_head_rcu(&dev->index_hlist,
  			   dev_index_hash(net, dev->ifindex));
  	write_unlock_bh(&dev_base_lock);
  
  	dev_base_seq_inc(net);
  }
  
  /* Device list removal
   * caller must respect a RCU grace period before freeing/reusing dev
   */
  static void unlist_netdevice(struct net_device *dev)
  {
  	ASSERT_RTNL();
  
  	/* Unlink dev from the device chain */
  	write_lock_bh(&dev_base_lock);
  	list_del_rcu(&dev->dev_list);
  	hlist_del_rcu(&dev->name_hlist);
  	hlist_del_rcu(&dev->index_hlist);
  	write_unlock_bh(&dev_base_lock);
  
  	dev_base_seq_inc(dev_net(dev));
  }
  
  /*
   *	Our notifier list
   */
  
  static RAW_NOTIFIER_HEAD(netdev_chain);
  
  /*
   *	Device drivers call our routines to queue packets here. We empty the
   *	queue in the local softnet handler.
   */
  
  DEFINE_PER_CPU_ALIGNED(struct softnet_data, softnet_data);
  EXPORT_PER_CPU_SYMBOL(softnet_data);
  
  /*******************************************************************************
   *
   *		Protocol management and registration routines
   *
   *******************************************************************************/
  
  
  /*
   *	Add a protocol ID to the list. Now that the input handler is
   *	smarter we can dispense with all the messy stuff that used to be
   *	here.
   *
   *	BEWARE!!! Protocol handlers, mangling input packets,
   *	MUST BE last in hash buckets and checking protocol handlers
   *	MUST start from promiscuous ptype_all chain in net_bh.
   *	It is true now, do not change it.
   *	Explanation follows: if protocol handler, mangling packet, will
   *	be the first on list, it is not able to sense, that packet
   *	is cloned and should be copied-on-write, so that it will
   *	change it and subsequent readers will get broken packet.
   *							--ANK (980803)
   */
  
  static inline struct list_head *ptype_head(const struct packet_type *pt)
  {
  	if (pt->type == htons(ETH_P_ALL))
  		return pt->dev ? &pt->dev->ptype_all : &ptype_all;
  	else
  		return pt->dev ? &pt->dev->ptype_specific :
  				 &ptype_base[ntohs(pt->type) & PTYPE_HASH_MASK];
  }
  
  /**
   *	dev_add_pack - add packet handler
   *	@pt: packet type declaration
   *
   *	Add a protocol handler to the networking stack. The passed &packet_type
   *	is linked into kernel lists and may not be freed until it has been
   *	removed from the kernel lists.
   *
   *	This call does not sleep therefore it can not
   *	guarantee all CPU's that are in middle of receiving packets
   *	will see the new packet type (until the next received packet).
   */
  
  void dev_add_pack(struct packet_type *pt)
  {
  	struct list_head *head = ptype_head(pt);
  
  	spin_lock(&ptype_lock);
  	list_add_rcu(&pt->list, head);
  	spin_unlock(&ptype_lock);
  }
  EXPORT_SYMBOL(dev_add_pack);
  
  /**
   *	__dev_remove_pack	 - remove packet handler
   *	@pt: packet type declaration
   *
   *	Remove a protocol handler that was previously added to the kernel
   *	protocol handlers by dev_add_pack(). The passed &packet_type is removed
   *	from the kernel lists and can be freed or reused once this function
   *	returns.
   *
   *      The packet type might still be in use by receivers
   *	and must not be freed until after all the CPU's have gone
   *	through a quiescent state.
   */
  void __dev_remove_pack(struct packet_type *pt)
  {
  	struct list_head *head = ptype_head(pt);
  	struct packet_type *pt1;
  
  	spin_lock(&ptype_lock);
  
  	list_for_each_entry(pt1, head, list) {
  		if (pt == pt1) {
  			list_del_rcu(&pt->list);
  			goto out;
  		}
  	}
  
  	pr_warn("dev_remove_pack: %p not found\n", pt);
  out:
  	spin_unlock(&ptype_lock);
  }
  EXPORT_SYMBOL(__dev_remove_pack);
  
  /**
   *	dev_remove_pack	 - remove packet handler
   *	@pt: packet type declaration
   *
   *	Remove a protocol handler that was previously added to the kernel
   *	protocol handlers by dev_add_pack(). The passed &packet_type is removed
   *	from the kernel lists and can be freed or reused once this function
   *	returns.
   *
   *	This call sleeps to guarantee that no CPU is looking at the packet
   *	type after return.
   */
  void dev_remove_pack(struct packet_type *pt)
  {
  	__dev_remove_pack(pt);
  
  	synchronize_net();
  }
  EXPORT_SYMBOL(dev_remove_pack);
  
  
  /**
   *	dev_add_offload - register offload handlers
   *	@po: protocol offload declaration
   *
   *	Add protocol offload handlers to the networking stack. The passed
   *	&proto_offload is linked into kernel lists and may not be freed until
   *	it has been removed from the kernel lists.
   *
   *	This call does not sleep therefore it can not
   *	guarantee all CPU's that are in middle of receiving packets
   *	will see the new offload handlers (until the next received packet).
   */
  void dev_add_offload(struct packet_offload *po)
  {
  	struct packet_offload *elem;
  
  	spin_lock(&offload_lock);
  	list_for_each_entry(elem, &offload_base, list) {
  		if (po->priority < elem->priority)
  			break;
  	}
  	list_add_rcu(&po->list, elem->list.prev);
  	spin_unlock(&offload_lock);
  }
  EXPORT_SYMBOL(dev_add_offload);
  
  /**
   *	__dev_remove_offload	 - remove offload handler
   *	@po: packet offload declaration
   *
   *	Remove a protocol offload handler that was previously added to the
   *	kernel offload handlers by dev_add_offload(). The passed &offload_type
   *	is removed from the kernel lists and can be freed or reused once this
   *	function returns.
   *
   *      The packet type might still be in use by receivers
   *	and must not be freed until after all the CPU's have gone
   *	through a quiescent state.
   */
  static void __dev_remove_offload(struct packet_offload *po)
  {
  	struct list_head *head = &offload_base;
  	struct packet_offload *po1;
  
  	spin_lock(&offload_lock);
  
  	list_for_each_entry(po1, head, list) {
  		if (po == po1) {
  			list_del_rcu(&po->list);
  			goto out;
  		}
  	}
  
  	pr_warn("dev_remove_offload: %p not found\n", po);
  out:
  	spin_unlock(&offload_lock);
  }
  
  /**
   *	dev_remove_offload	 - remove packet offload handler
   *	@po: packet offload declaration
   *
   *	Remove a packet offload handler that was previously added to the kernel
   *	offload handlers by dev_add_offload(). The passed &offload_type is
   *	removed from the kernel lists and can be freed or reused once this
   *	function returns.
   *
   *	This call sleeps to guarantee that no CPU is looking at the packet
   *	type after return.
   */
  void dev_remove_offload(struct packet_offload *po)
  {
  	__dev_remove_offload(po);
  
  	synchronize_net();
  }
  EXPORT_SYMBOL(dev_remove_offload);
  
  /******************************************************************************
   *
   *		      Device Boot-time Settings Routines
   *
   ******************************************************************************/
  
  /* Boot time configuration table */
  static struct netdev_boot_setup dev_boot_setup[NETDEV_BOOT_SETUP_MAX];
  
  /**
   *	netdev_boot_setup_add	- add new setup entry
   *	@name: name of the device
   *	@map: configured settings for the device
   *
   *	Adds new setup entry to the dev_boot_setup list.  The function
   *	returns 0 on error and 1 on success.  This is a generic routine to
   *	all netdevices.
   */
  static int netdev_boot_setup_add(char *name, struct ifmap *map)
  {
  	struct netdev_boot_setup *s;
  	int i;
  
  	s = dev_boot_setup;
  	for (i = 0; i < NETDEV_BOOT_SETUP_MAX; i++) {
  		if (s[i].name[0] == '\0' || s[i].name[0] == ' ') {
  			memset(s[i].name, 0, sizeof(s[i].name));
  			strlcpy(s[i].name, name, IFNAMSIZ);
  			memcpy(&s[i].map, map, sizeof(s[i].map));
  			break;
  		}
  	}
  
  	return i >= NETDEV_BOOT_SETUP_MAX ? 0 : 1;
  }
  
  /**
   * netdev_boot_setup_check	- check boot time settings
   * @dev: the netdevice
   *
   * Check boot time settings for the device.
   * The found settings are set for the device to be used
   * later in the device probing.
   * Returns 0 if no settings found, 1 if they are.
   */
  int netdev_boot_setup_check(struct net_device *dev)
  {
  	struct netdev_boot_setup *s = dev_boot_setup;
  	int i;
  
  	for (i = 0; i < NETDEV_BOOT_SETUP_MAX; i++) {
  		if (s[i].name[0] != '\0' && s[i].name[0] != ' ' &&
  		    !strcmp(dev->name, s[i].name)) {
  			dev->irq = s[i].map.irq;
  			dev->base_addr = s[i].map.base_addr;
  			dev->mem_start = s[i].map.mem_start;
  			dev->mem_end = s[i].map.mem_end;
  			return 1;
  		}
  	}
  	return 0;
  }
  EXPORT_SYMBOL(netdev_boot_setup_check);
  
  
  /**
   * netdev_boot_base	- get address from boot time settings
   * @prefix: prefix for network device
   * @unit: id for network device
   *
   * Check boot time settings for the base address of device.
   * The found settings are set for the device to be used
   * later in the device probing.
   * Returns 0 if no settings found.
   */
  unsigned long netdev_boot_base(const char *prefix, int unit)
  {
  	const struct netdev_boot_setup *s = dev_boot_setup;
  	char name[IFNAMSIZ];
  	int i;
  
  	sprintf(name, "%s%d", prefix, unit);
  
  	/*
  	 * If device already registered then return base of 1
  	 * to indicate not to probe for this interface
  	 */
  	if (__dev_get_by_name(&init_net, name))
  		return 1;
  
  	for (i = 0; i < NETDEV_BOOT_SETUP_MAX; i++)
  		if (!strcmp(name, s[i].name))
  			return s[i].map.base_addr;
  	return 0;
  }
  
  /*
   * Saves at boot time configured settings for any netdevice.
   */
  int __init netdev_boot_setup(char *str)
  {
  	int ints[5];
  	struct ifmap map;
  
  	str = get_options(str, ARRAY_SIZE(ints), ints);
  	if (!str || !*str)
  		return 0;
  
  	/* Save settings */
  	memset(&map, 0, sizeof(map));
  	if (ints[0] > 0)
  		map.irq = ints[1];
  	if (ints[0] > 1)
  		map.base_addr = ints[2];
  	if (ints[0] > 2)
  		map.mem_start = ints[3];
  	if (ints[0] > 3)
  		map.mem_end = ints[4];
  
  	/* Add new entry to the list */
  	return netdev_boot_setup_add(str, &map);
  }
  
  __setup("netdev=", netdev_boot_setup);
  
  /*******************************************************************************
   *
   *			    Device Interface Subroutines
   *
   *******************************************************************************/
  
  /**
   *	dev_get_iflink	- get 'iflink' value of a interface
   *	@dev: targeted interface
   *
   *	Indicates the ifindex the interface is linked to.
   *	Physical interfaces have the same 'ifindex' and 'iflink' values.
   */
  
  int dev_get_iflink(const struct net_device *dev)
  {
  	if (dev->netdev_ops && dev->netdev_ops->ndo_get_iflink)
  		return dev->netdev_ops->ndo_get_iflink(dev);
  
  	return dev->ifindex;
  }
  EXPORT_SYMBOL(dev_get_iflink);
  
  /**
   *	dev_fill_metadata_dst - Retrieve tunnel egress information.
   *	@dev: targeted interface
   *	@skb: The packet.
   *
   *	For better visibility of tunnel traffic OVS needs to retrieve
   *	egress tunnel information for a packet. Following API allows
   *	user to get this info.
   */
  int dev_fill_metadata_dst(struct net_device *dev, struct sk_buff *skb)
  {
  	struct ip_tunnel_info *info;
  
  	if (!dev->netdev_ops  || !dev->netdev_ops->ndo_fill_metadata_dst)
  		return -EINVAL;
  
  	info = skb_tunnel_info_unclone(skb);
  	if (!info)
  		return -ENOMEM;
  	if (unlikely(!(info->mode & IP_TUNNEL_INFO_TX)))
  		return -EINVAL;
  
  	return dev->netdev_ops->ndo_fill_metadata_dst(dev, skb);
  }
  EXPORT_SYMBOL_GPL(dev_fill_metadata_dst);
  
  /**
   *	__dev_get_by_name	- find a device by its name
   *	@net: the applicable net namespace
   *	@name: name to find
   *
   *	Find an interface by name. Must be called under RTNL semaphore
   *	or @dev_base_lock. If the name is found a pointer to the device
   *	is returned. If the name is not found then %NULL is returned. The
   *	reference counters are not incremented so the caller must be
   *	careful with locks.
   */
  
  struct net_device *__dev_get_by_name(struct net *net, const char *name)
  {
  	struct net_device *dev;
  	struct hlist_head *head = dev_name_hash(net, name);
  
  	hlist_for_each_entry(dev, head, name_hlist)
  		if (!strncmp(dev->name, name, IFNAMSIZ))
  			return dev;
  
  	return NULL;
  }
  EXPORT_SYMBOL(__dev_get_by_name);
  
  /**
   * dev_get_by_name_rcu	- find a device by its name
   * @net: the applicable net namespace
   * @name: name to find
   *
   * Find an interface by name.
   * If the name is found a pointer to the device is returned.
   * If the name is not found then %NULL is returned.
   * The reference counters are not incremented so the caller must be
   * careful with locks. The caller must hold RCU lock.
   */
  
  struct net_device *dev_get_by_name_rcu(struct net *net, const char *name)
  {
  	struct net_device *dev;
  	struct hlist_head *head = dev_name_hash(net, name);
  
  	hlist_for_each_entry_rcu(dev, head, name_hlist)
  		if (!strncmp(dev->name, name, IFNAMSIZ))
  			return dev;
  
  	return NULL;
  }
  EXPORT_SYMBOL(dev_get_by_name_rcu);
  
  /**
   *	dev_get_by_name		- find a device by its name
   *	@net: the applicable net namespace
   *	@name: name to find
   *
   *	Find an interface by name. This can be called from any
   *	context and does its own locking. The returned handle has
   *	the usage count incremented and the caller must use dev_put() to
   *	release it when it is no longer needed. %NULL is returned if no
   *	matching device is found.
   */
  
  struct net_device *dev_get_by_name(struct net *net, const char *name)
  {
  	struct net_device *dev;
  
  	rcu_read_lock();
  	dev = dev_get_by_name_rcu(net, name);
  	if (dev)
  		dev_hold(dev);
  	rcu_read_unlock();
  	return dev;
  }
  EXPORT_SYMBOL(dev_get_by_name);
  
  /**
   *	__dev_get_by_index - find a device by its ifindex
   *	@net: the applicable net namespace
   *	@ifindex: index of device
   *
   *	Search for an interface by index. Returns %NULL if the device
   *	is not found or a pointer to the device. The device has not
   *	had its reference counter increased so the caller must be careful
   *	about locking. The caller must hold either the RTNL semaphore
   *	or @dev_base_lock.
   */
  
  struct net_device *__dev_get_by_index(struct net *net, int ifindex)
  {
  	struct net_device *dev;
  	struct hlist_head *head = dev_index_hash(net, ifindex);
  
  	hlist_for_each_entry(dev, head, index_hlist)
  		if (dev->ifindex == ifindex)
  			return dev;
  
  	return NULL;
  }
  EXPORT_SYMBOL(__dev_get_by_index);
  
  /**
   *	dev_get_by_index_rcu - find a device by its ifindex
   *	@net: the applicable net namespace
   *	@ifindex: index of device
   *
   *	Search for an interface by index. Returns %NULL if the device
   *	is not found or a pointer to the device. The device has not
   *	had its reference counter increased so the caller must be careful
   *	about locking. The caller must hold RCU lock.
   */
  
  struct net_device *dev_get_by_index_rcu(struct net *net, int ifindex)
  {
  	struct net_device *dev;
  	struct hlist_head *head = dev_index_hash(net, ifindex);
  
  	hlist_for_each_entry_rcu(dev, head, index_hlist)
  		if (dev->ifindex == ifindex)
  			return dev;
  
  	return NULL;
  }
  EXPORT_SYMBOL(dev_get_by_index_rcu);
  
  
  /**
   *	dev_get_by_index - find a device by its ifindex
   *	@net: the applicable net namespace
   *	@ifindex: index of device
   *
   *	Search for an interface by index. Returns NULL if the device
   *	is not found or a pointer to the device. The device returned has
   *	had a reference added and the pointer is safe until the user calls
   *	dev_put to indicate they have finished with it.
   */
  
  struct net_device *dev_get_by_index(struct net *net, int ifindex)
  {
  	struct net_device *dev;
  
  	rcu_read_lock();
  	dev = dev_get_by_index_rcu(net, ifindex);
  	if (dev)
  		dev_hold(dev);
  	rcu_read_unlock();
  	return dev;
  }
  EXPORT_SYMBOL(dev_get_by_index);
  
  /**
   *	dev_get_by_napi_id - find a device by napi_id
   *	@napi_id: ID of the NAPI struct
   *
   *	Search for an interface by NAPI ID. Returns %NULL if the device
   *	is not found or a pointer to the device. The device has not had
   *	its reference counter increased so the caller must be careful
   *	about locking. The caller must hold RCU lock.
   */
  
  struct net_device *dev_get_by_napi_id(unsigned int napi_id)
  {
  	struct napi_struct *napi;
  
  	WARN_ON_ONCE(!rcu_read_lock_held());
  
  	if (napi_id < MIN_NAPI_ID)
  		return NULL;
  
  	napi = napi_by_id(napi_id);
  
  	return napi ? napi->dev : NULL;
  }
  EXPORT_SYMBOL(dev_get_by_napi_id);
  
  /**
   *	netdev_get_name - get a netdevice name, knowing its ifindex.
   *	@net: network namespace
   *	@name: a pointer to the buffer where the name will be stored.
   *	@ifindex: the ifindex of the interface to get the name from.
   */
  int netdev_get_name(struct net *net, char *name, int ifindex)
  {
  	struct net_device *dev;
  	int ret;
  
  	down_read(&devnet_rename_sem);
  	rcu_read_lock();
  
  	dev = dev_get_by_index_rcu(net, ifindex);
  	if (!dev) {
  		ret = -ENODEV;
  		goto out;
  	}
  
  	strcpy(name, dev->name);
  
  	ret = 0;
  out:
  	rcu_read_unlock();
  	up_read(&devnet_rename_sem);
  	return ret;
  }
  
  /**
   *	dev_getbyhwaddr_rcu - find a device by its hardware address
   *	@net: the applicable net namespace
   *	@type: media type of device
   *	@ha: hardware address
   *
   *	Search for an interface by MAC address. Returns NULL if the device
   *	is not found or a pointer to the device.
   *	The caller must hold RCU or RTNL.
   *	The returned device has not had its ref count increased
   *	and the caller must therefore be careful about locking
   *
   */
  
  struct net_device *dev_getbyhwaddr_rcu(struct net *net, unsigned short type,
  				       const char *ha)
  {
  	struct net_device *dev;
  
  	for_each_netdev_rcu(net, dev)
  		if (dev->type == type &&
  		    !memcmp(dev->dev_addr, ha, dev->addr_len))
  			return dev;
  
  	return NULL;
  }
  EXPORT_SYMBOL(dev_getbyhwaddr_rcu);
  
  struct net_device *__dev_getfirstbyhwtype(struct net *net, unsigned short type)
  {
  	struct net_device *dev;
  
  	ASSERT_RTNL();
  	for_each_netdev(net, dev)
  		if (dev->type == type)
  			return dev;
  
  	return NULL;
  }
  EXPORT_SYMBOL(__dev_getfirstbyhwtype);
  
  struct net_device *dev_getfirstbyhwtype(struct net *net, unsigned short type)
  {
  	struct net_device *dev, *ret = NULL;
  
  	rcu_read_lock();
  	for_each_netdev_rcu(net, dev)
  		if (dev->type == type) {
  			dev_hold(dev);
  			ret = dev;
  			break;
  		}
  	rcu_read_unlock();
  	return ret;
  }
  EXPORT_SYMBOL(dev_getfirstbyhwtype);
  
  /**
   *	__dev_get_by_flags - find any device with given flags
   *	@net: the applicable net namespace
   *	@if_flags: IFF_* values
   *	@mask: bitmask of bits in if_flags to check
   *
   *	Search for any interface with the given flags. Returns NULL if a device
   *	is not found or a pointer to the device. Must be called inside
   *	rtnl_lock(), and result refcount is unchanged.
   */
  
  struct net_device *__dev_get_by_flags(struct net *net, unsigned short if_flags,
  				      unsigned short mask)
  {
  	struct net_device *dev, *ret;
  
  	ASSERT_RTNL();
  
  	ret = NULL;
  	for_each_netdev(net, dev) {
  		if (((dev->flags ^ if_flags) & mask) == 0) {
  			ret = dev;
  			break;
  		}
  	}
  	return ret;
  }
  EXPORT_SYMBOL(__dev_get_by_flags);
  
  /**
   *	dev_valid_name - check if name is okay for network device
   *	@name: name string
   *
   *	Network device names need to be valid file names to
   *	to allow sysfs to work.  We also disallow any kind of
   *	whitespace.
   */
  bool dev_valid_name(const char *name)
  {
  	if (*name == '\0')
  		return false;
  	if (strnlen(name, IFNAMSIZ) == IFNAMSIZ)
  		return false;
  	if (!strcmp(name, ".") || !strcmp(name, ".."))
  		return false;
  
  	while (*name) {
  		if (*name == '/' || *name == ':' || isspace(*name))
  			return false;
  		name++;
  	}
  	return true;
  }
  EXPORT_SYMBOL(dev_valid_name);
  
  /**
   *	__dev_alloc_name - allocate a name for a device
   *	@net: network namespace to allocate the device name in
   *	@name: name format string
   *	@buf:  scratch buffer and result name string
   *
   *	Passed a format string - eg "lt%d" it will try and find a suitable
   *	id. It scans list of devices to build up a free map, then chooses
   *	the first empty slot. The caller must hold the dev_base or rtnl lock
   *	while allocating the name and adding the device in order to avoid
   *	duplicates.
   *	Limited to bits_per_byte * page size devices (ie 32K on most platforms).
   *	Returns the number of the unit assigned or a negative errno code.
   */
  
  static int __dev_alloc_name(struct net *net, const char *name, char *buf)
  {
  	int i = 0;
  	const char *p;
  	const int max_netdevices = 8*PAGE_SIZE;
  	unsigned long *inuse;
  	struct net_device *d;
  
  	if (!dev_valid_name(name))
  		return -EINVAL;
  
  	p = strchr(name, '%');
  	if (p) {
  		/*
  		 * Verify the string as this thing may have come from
  		 * the user.  There must be either one "%d" and no other "%"
  		 * characters.
  		 */
  		if (p[1] != 'd' || strchr(p + 2, '%'))
  			return -EINVAL;
  
  		/* Use one page as a bit array of possible slots */
  		inuse = (unsigned long *) get_zeroed_page(GFP_ATOMIC);
  		if (!inuse)
  			return -ENOMEM;
  
  		for_each_netdev(net, d) {
  			if (!sscanf(d->name, name, &i))
  				continue;
  			if (i < 0 || i >= max_netdevices)
  				continue;
  
  			/*  avoid cases where sscanf is not exact inverse of printf */
  			snprintf(buf, IFNAMSIZ, name, i);
  			if (!strncmp(buf, d->name, IFNAMSIZ))
  				set_bit(i, inuse);
  		}
  
  		i = find_first_zero_bit(inuse, max_netdevices);
  		free_page((unsigned long) inuse);
  	}
  
  	snprintf(buf, IFNAMSIZ, name, i);
  	if (!__dev_get_by_name(net, buf))
  		return i;
  
  	/* It is possible to run out of possible slots
  	 * when the name is long and there isn't enough space left
  	 * for the digits, or if all bits are used.
  	 */
  	return -ENFILE;
  }
  
  static int dev_alloc_name_ns(struct net *net,
  			     struct net_device *dev,
  			     const char *name)
  {
  	char buf[IFNAMSIZ];
  	int ret;
  
  	BUG_ON(!net);
  	ret = __dev_alloc_name(net, name, buf);
  	if (ret >= 0)
  		strlcpy(dev->name, buf, IFNAMSIZ);
  	return ret;
  }
  
  /**
   *	dev_alloc_name - allocate a name for a device
   *	@dev: device
   *	@name: name format string
   *
   *	Passed a format string - eg "lt%d" it will try and find a suitable
   *	id. It scans list of devices to build up a free map, then chooses
   *	the first empty slot. The caller must hold the dev_base or rtnl lock
   *	while allocating the name and adding the device in order to avoid
   *	duplicates.
   *	Limited to bits_per_byte * page size devices (ie 32K on most platforms).
   *	Returns the number of the unit assigned or a negative errno code.
   */
  
  int dev_alloc_name(struct net_device *dev, const char *name)
  {
  	return dev_alloc_name_ns(dev_net(dev), dev, name);
  }
  EXPORT_SYMBOL(dev_alloc_name);
  
  int dev_get_valid_name(struct net *net, struct net_device *dev,
  		       const char *name)
  {
  	BUG_ON(!net);
  
  	if (!dev_valid_name(name))
  		return -EINVAL;
  
  	if (strchr(name, '%'))
  		return dev_alloc_name_ns(net, dev, name);
  	else if (__dev_get_by_name(net, name))
  		return -EEXIST;
  	else if (dev->name != name)
  		strlcpy(dev->name, name, IFNAMSIZ);
  
  	return 0;
  }
  EXPORT_SYMBOL(dev_get_valid_name);
  
  /**
   *	dev_change_name - change name of a device
   *	@dev: device
   *	@newname: name (or format string) must be at least IFNAMSIZ
   *
   *	Change name of a device, can pass format strings "eth%d".
   *	for wildcarding.
   */
  int dev_change_name(struct net_device *dev, const char *newname)
  {
  	unsigned char old_assign_type;
  	char oldname[IFNAMSIZ];
  	int err = 0;
  	int ret;
  	struct net *net;
  
  	ASSERT_RTNL();
  	BUG_ON(!dev_net(dev));
  
  	net = dev_net(dev);
  
  	/* Some auto-enslaved devices e.g. failover slaves are
  	 * special, as userspace might rename the device after
  	 * the interface had been brought up and running since
  	 * the point kernel initiated auto-enslavement. Allow
  	 * live name change even when these slave devices are
  	 * up and running.
  	 *
  	 * Typically, users of these auto-enslaving devices
  	 * don't actually care about slave name change, as
  	 * they are supposed to operate on master interface
  	 * directly.
  	 */
  	if (dev->flags & IFF_UP &&
  	    likely(!(dev->priv_flags & IFF_LIVE_RENAME_OK)))
  		return -EBUSY;
  
  	down_write(&devnet_rename_sem);
  
  	if (strncmp(newname, dev->name, IFNAMSIZ) == 0) {
  		up_write(&devnet_rename_sem);
  		return 0;
  	}
  
  	memcpy(oldname, dev->name, IFNAMSIZ);
  
  	err = dev_get_valid_name(net, dev, newname);
  	if (err < 0) {
  		up_write(&devnet_rename_sem);
  		return err;
  	}
  
  	if (oldname[0] && !strchr(oldname, '%'))
  		netdev_info(dev, "renamed from %s\n", oldname);
  
  	old_assign_type = dev->name_assign_type;
  	dev->name_assign_type = NET_NAME_RENAMED;
  
  rollback:
  	ret = device_rename(&dev->dev, dev->name);
  	if (ret) {
  		memcpy(dev->name, oldname, IFNAMSIZ);
  		dev->name_assign_type = old_assign_type;
  		up_write(&devnet_rename_sem);
  		return ret;
  	}
  
  	up_write(&devnet_rename_sem);
  
  	netdev_adjacent_rename_links(dev, oldname);
  
  	write_lock_bh(&dev_base_lock);
  	hlist_del_rcu(&dev->name_hlist);
  	write_unlock_bh(&dev_base_lock);
  
  	synchronize_rcu();
  
  	write_lock_bh(&dev_base_lock);
  	hlist_add_head_rcu(&dev->name_hlist, dev_name_hash(net, dev->name));
  	write_unlock_bh(&dev_base_lock);
  
  	ret = call_netdevice_notifiers(NETDEV_CHANGENAME, dev);
  	ret = notifier_to_errno(ret);
  
  	if (ret) {
  		/* err >= 0 after dev_alloc_name() or stores the first errno */
  		if (err >= 0) {
  			err = ret;
  			down_write(&devnet_rename_sem);
  			memcpy(dev->name, oldname, IFNAMSIZ);
  			memcpy(oldname, newname, IFNAMSIZ);
  			dev->name_assign_type = old_assign_type;
  			old_assign_type = NET_NAME_RENAMED;
  			goto rollback;
  		} else {
  			pr_err("%s: name change rollback failed: %d\n",
  			       dev->name, ret);
  		}
  	}
  
  	return err;
  }
  
  /**
   *	dev_set_alias - change ifalias of a device
   *	@dev: device
   *	@alias: name up to IFALIASZ
   *	@len: limit of bytes to copy from info
   *
   *	Set ifalias for a device,
   */
  int dev_set_alias(struct net_device *dev, const char *alias, size_t len)
  {
  	struct dev_ifalias *new_alias = NULL;
  
  	if (len >= IFALIASZ)
  		return -EINVAL;
  
  	if (len) {
  		new_alias = kmalloc(sizeof(*new_alias) + len + 1, GFP_KERNEL);
  		if (!new_alias)
  			return -ENOMEM;
  
  		memcpy(new_alias->ifalias, alias, len);
  		new_alias->ifalias[len] = 0;
  	}
  
  	mutex_lock(&ifalias_mutex);
  	rcu_swap_protected(dev->ifalias, new_alias,
  			   mutex_is_locked(&ifalias_mutex));
  	mutex_unlock(&ifalias_mutex);
  
  	if (new_alias)
  		kfree_rcu(new_alias, rcuhead);
  
  	return len;
  }
  EXPORT_SYMBOL(dev_set_alias);
  
  /**
   *	dev_get_alias - get ifalias of a device
   *	@dev: device
   *	@name: buffer to store name of ifalias
   *	@len: size of buffer
   *
   *	get ifalias for a device.  Caller must make sure dev cannot go
   *	away,  e.g. rcu read lock or own a reference count to device.
   */
  int dev_get_alias(const struct net_device *dev, char *name, size_t len)
  {
  	const struct dev_ifalias *alias;
  	int ret = 0;
  
  	rcu_read_lock();
  	alias = rcu_dereference(dev->ifalias);
  	if (alias)
  		ret = snprintf(name, len, "%s", alias->ifalias);
  	rcu_read_unlock();
  
  	return ret;
  }
  
  /**
   *	netdev_features_change - device changes features
   *	@dev: device to cause notification
   *
   *	Called to indicate a device has changed features.
   */
  void netdev_features_change(struct net_device *dev)
  {
  	call_netdevice_notifiers(NETDEV_FEAT_CHANGE, dev);
  }
  EXPORT_SYMBOL(netdev_features_change);
  
  /**
   *	netdev_state_change - device changes state
   *	@dev: device to cause notification
   *
   *	Called to indicate a device has changed state. This function calls
   *	the notifier chains for netdev_chain and sends a NEWLINK message
   *	to the routing socket.
   */
  void netdev_state_change(struct net_device *dev)
  {
  	if (dev->flags & IFF_UP) {
  		struct netdev_notifier_change_info change_info = {
  			.info.dev = dev,
  		};
  
  		call_netdevice_notifiers_info(NETDEV_CHANGE,
  					      &change_info.info);
  		rtmsg_ifinfo(RTM_NEWLINK, dev, 0, GFP_KERNEL);
  	}
  }
  EXPORT_SYMBOL(netdev_state_change);
  
  /**
   * netdev_notify_peers - notify network peers about existence of @dev
   * @dev: network device
   *
   * Generate traffic such that interested network peers are aware of
   * @dev, such as by generating a gratuitous ARP. This may be used when
   * a device wants to inform the rest of the network about some sort of
   * reconfiguration such as a failover event or virtual machine
   * migration.
   */
  void netdev_notify_peers(struct net_device *dev)
  {
  	rtnl_lock();
  	call_netdevice_notifiers(NETDEV_NOTIFY_PEERS, dev);
  	call_netdevice_notifiers(NETDEV_RESEND_IGMP, dev);
  	rtnl_unlock();
  }
  EXPORT_SYMBOL(netdev_notify_peers);
  
  static int __dev_open(struct net_device *dev, struct netlink_ext_ack *extack)
  {
  	const struct net_device_ops *ops = dev->netdev_ops;
  	int ret;
  
  	ASSERT_RTNL();
  
  	if (!netif_device_present(dev))
  		return -ENODEV;
  
  	/* Block netpoll from trying to do any rx path servicing.
  	 * If we don't do this there is a chance ndo_poll_controller
  	 * or ndo_poll may be running while we open the device
  	 */
  	netpoll_poll_disable(dev);
  
  	ret = call_netdevice_notifiers_extack(NETDEV_PRE_UP, dev, extack);
  	ret = notifier_to_errno(ret);
  	if (ret)
  		return ret;
  
  	set_bit(__LINK_STATE_START, &dev->state);
  
  	if (ops->ndo_validate_addr)
  		ret = ops->ndo_validate_addr(dev);
  
  	if (!ret && ops->ndo_open)
  		ret = ops->ndo_open(dev);
  
  	netpoll_poll_enable(dev);
  
  	if (ret)
  		clear_bit(__LINK_STATE_START, &dev->state);
  	else {
  		dev->flags |= IFF_UP;
  		dev_set_rx_mode(dev);
  		dev_activate(dev);
  		add_device_randomness(dev->dev_addr, dev->addr_len);
  	}
  
  	return ret;
  }
  
  /**
   *	dev_open	- prepare an interface for use.
   *	@dev: device to open
   *	@extack: netlink extended ack
   *
   *	Takes a device from down to up state. The device's private open
   *	function is invoked and then the multicast lists are loaded. Finally
   *	the device is moved into the up state and a %NETDEV_UP message is
   *	sent to the netdev notifier chain.
   *
   *	Calling this function on an active interface is a nop. On a failure
   *	a negative errno code is returned.
   */
  int dev_open(struct net_device *dev, struct netlink_ext_ack *extack)
  {
  	int ret;
  
  	if (dev->flags & IFF_UP)
  		return 0;
  
  	ret = __dev_open(dev, extack);
  	if (ret < 0)
  		return ret;
  
  	rtmsg_ifinfo(RTM_NEWLINK, dev, IFF_UP|IFF_RUNNING, GFP_KERNEL);
  	call_netdevice_notifiers(NETDEV_UP, dev);
  
  	return ret;
  }
  EXPORT_SYMBOL(dev_open);
  
  static void __dev_close_many(struct list_head *head)
  {
  	struct net_device *dev;
  
  	ASSERT_RTNL();
  	might_sleep();
  
  	list_for_each_entry(dev, head, close_list) {
  		/* Temporarily disable netpoll until the interface is down */
  		netpoll_poll_disable(dev);
  
  		call_netdevice_notifiers(NETDEV_GOING_DOWN, dev);
  
  		clear_bit(__LINK_STATE_START, &dev->state);
  
  		/* Synchronize to scheduled poll. We cannot touch poll list, it
  		 * can be even on different cpu. So just clear netif_running().
  		 *
  		 * dev->stop() will invoke napi_disable() on all of it's
  		 * napi_struct instances on this device.
  		 */
  		smp_mb__after_atomic(); /* Commit netif_running(). */
  	}
  
  	dev_deactivate_many(head);
  
  	list_for_each_entry(dev, head, close_list) {
  		const struct net_device_ops *ops = dev->netdev_ops;
  
  		/*
  		 *	Call the device specific close. This cannot fail.
  		 *	Only if device is UP
  		 *
  		 *	We allow it to be called even after a DETACH hot-plug
  		 *	event.
  		 */
  		if (ops->ndo_stop)
  			ops->ndo_stop(dev);
  
  		dev->flags &= ~IFF_UP;
  		netpoll_poll_enable(dev);
  	}
  }
  
  static void __dev_close(struct net_device *dev)
  {
  	LIST_HEAD(single);
  
  	list_add(&dev->close_list, &single);
  	__dev_close_many(&single);
  	list_del(&single);
  }
  
  void dev_close_many(struct list_head *head, bool unlink)
  {
  	struct net_device *dev, *tmp;
  
  	/* Remove the devices that don't need to be closed */
  	list_for_each_entry_safe(dev, tmp, head, close_list)
  		if (!(dev->flags & IFF_UP))
  			list_del_init(&dev->close_list);
  
  	__dev_close_many(head);
  
  	list_for_each_entry_safe(dev, tmp, head, close_list) {
  		rtmsg_ifinfo(RTM_NEWLINK, dev, IFF_UP|IFF_RUNNING, GFP_KERNEL);
  		call_netdevice_notifiers(NETDEV_DOWN, dev);
  		if (unlink)
  			list_del_init(&dev->close_list);
  	}
  }
  EXPORT_SYMBOL(dev_close_many);
  
  /**
   *	dev_close - shutdown an interface.
   *	@dev: device to shutdown
   *
   *	This function moves an active device into down state. A
   *	%NETDEV_GOING_DOWN is sent to the netdev notifier chain. The device
   *	is then deactivated and finally a %NETDEV_DOWN is sent to the notifier
   *	chain.
   */
  void dev_close(struct net_device *dev)
  {
  	if (dev->flags & IFF_UP) {
  		LIST_HEAD(single);
  
  		list_add(&dev->close_list, &single);
  		dev_close_many(&single, true);
  		list_del(&single);
  	}
  }
  EXPORT_SYMBOL(dev_close);
  
  
  /**
   *	dev_disable_lro - disable Large Receive Offload on a device
   *	@dev: device
   *
   *	Disable Large Receive Offload (LRO) on a net device.  Must be
   *	called under RTNL.  This is needed if received packets may be
   *	forwarded to another interface.
   */
  void dev_disable_lro(struct net_device *dev)
  {
  	struct net_device *lower_dev;
  	struct list_head *iter;
  
  	dev->wanted_features &= ~NETIF_F_LRO;
  	netdev_update_features(dev);
  
  	if (unlikely(dev->features & NETIF_F_LRO))
  		netdev_WARN(dev, "failed to disable LRO!\n");
  
  	netdev_for_each_lower_dev(dev, lower_dev, iter)
  		dev_disable_lro(lower_dev);
  }
  EXPORT_SYMBOL(dev_disable_lro);
  
  /**
   *	dev_disable_gro_hw - disable HW Generic Receive Offload on a device
   *	@dev: device
   *
   *	Disable HW Generic Receive Offload (GRO_HW) on a net device.  Must be
   *	called under RTNL.  This is needed if Generic XDP is installed on
   *	the device.
   */
  static void dev_disable_gro_hw(struct net_device *dev)
  {
  	dev->wanted_features &= ~NETIF_F_GRO_HW;
  	netdev_update_features(dev);
  
  	if (unlikely(dev->features & NETIF_F_GRO_HW))
  		netdev_WARN(dev, "failed to disable GRO_HW!\n");
  }
  
  const char *netdev_cmd_to_name(enum netdev_cmd cmd)
  {
  #define N(val) 						\
  	case NETDEV_##val:				\
  		return "NETDEV_" __stringify(val);
  	switch (cmd) {
  	N(UP) N(DOWN) N(REBOOT) N(CHANGE) N(REGISTER) N(UNREGISTER)
  	N(CHANGEMTU) N(CHANGEADDR) N(GOING_DOWN) N(CHANGENAME) N(FEAT_CHANGE)
  	N(BONDING_FAILOVER) N(PRE_UP) N(PRE_TYPE_CHANGE) N(POST_TYPE_CHANGE)
  	N(POST_INIT) N(RELEASE) N(NOTIFY_PEERS) N(JOIN) N(CHANGEUPPER)
  	N(RESEND_IGMP) N(PRECHANGEMTU) N(CHANGEINFODATA) N(BONDING_INFO)
  	N(PRECHANGEUPPER) N(CHANGELOWERSTATE) N(UDP_TUNNEL_PUSH_INFO)
  	N(UDP_TUNNEL_DROP_INFO) N(CHANGE_TX_QUEUE_LEN)
  	N(CVLAN_FILTER_PUSH_INFO) N(CVLAN_FILTER_DROP_INFO)
  	N(SVLAN_FILTER_PUSH_INFO) N(SVLAN_FILTER_DROP_INFO)
  	N(PRE_CHANGEADDR)
  	}
  #undef N
  	return "UNKNOWN_NETDEV_EVENT";
  }
  EXPORT_SYMBOL_GPL(netdev_cmd_to_name);
  
  static int call_netdevice_notifier(struct notifier_block *nb, unsigned long val,
  				   struct net_device *dev)
  {
  	struct netdev_notifier_info info = {
  		.dev = dev,
  	};
  
  	return nb->notifier_call(nb, val, &info);
  }
  
  static int dev_boot_phase = 1;
  
  /**
   * register_netdevice_notifier - register a network notifier block
   * @nb: notifier
   *
   * Register a notifier to be called when network device events occur.
   * The notifier passed is linked into the kernel structures and must
   * not be reused until it has been unregistered. A negative errno code
   * is returned on a failure.
   *
   * When registered all registration and up events are replayed
   * to the new notifier to allow device to have a race free
   * view of the network device list.
   */
  
  int register_netdevice_notifier(struct notifier_block *nb)
  {
  	struct net_device *dev;
  	struct net_device *last;
  	struct net *net;
  	int err;
  
  	/* Close race with setup_net() and cleanup_net() */
  	down_write(&pernet_ops_rwsem);
  	rtnl_lock();
  	err = raw_notifier_chain_register(&netdev_chain, nb);
  	if (err)
  		goto unlock;
  	if (dev_boot_phase)
  		goto unlock;
  	for_each_net(net) {
  		for_each_netdev(net, dev) {
  			err = call_netdevice_notifier(nb, NETDEV_REGISTER, dev);
  			err = notifier_to_errno(err);
  			if (err)
  				goto rollback;
  
  			if (!(dev->flags & IFF_UP))
  				continue;
  
  			call_netdevice_notifier(nb, NETDEV_UP, dev);
  		}
  	}
  
  unlock:
  	rtnl_unlock();
  	up_write(&pernet_ops_rwsem);
  	return err;
  
  rollback:
  	last = dev;
  	for_each_net(net) {
  		for_each_netdev(net, dev) {
  			if (dev == last)
  				goto outroll;
  
  			if (dev->flags & IFF_UP) {
  				call_netdevice_notifier(nb, NETDEV_GOING_DOWN,
  							dev);
  				call_netdevice_notifier(nb, NETDEV_DOWN, dev);
  			}
  			call_netdevice_notifier(nb, NETDEV_UNREGISTER, dev);
  		}
  	}
  
  outroll:
  	raw_notifier_chain_unregister(&netdev_chain, nb);
  	goto unlock;
  }
  EXPORT_SYMBOL(register_netdevice_notifier);
  
  /**
   * unregister_netdevice_notifier - unregister a network notifier block
   * @nb: notifier
   *
   * Unregister a notifier previously registered by
   * register_netdevice_notifier(). The notifier is unlinked into the
   * kernel structures and may then be reused. A negative errno code
   * is returned on a failure.
   *
   * After unregistering unregister and down device events are synthesized
   * for all devices on the device list to the removed notifier to remove
   * the need for special case cleanup code.
   */
  
  int unregister_netdevice_notifier(struct notifier_block *nb)
  {
  	struct net_device *dev;
  	struct net *net;
  	int err;
  
  	/* Close race with setup_net() and cleanup_net() */
  	down_write(&pernet_ops_rwsem);
  	rtnl_lock();
  	err = raw_notifier_chain_unregister(&netdev_chain, nb);
  	if (err)
  		goto unlock;
  
  	for_each_net(net) {
  		for_each_netdev(net, dev) {
  			if (dev->flags & IFF_UP) {
  				call_netdevice_notifier(nb, NETDEV_GOING_DOWN,
  							dev);
  				call_netdevice_notifier(nb, NETDEV_DOWN, dev);
  			}
  			call_netdevice_notifier(nb, NETDEV_UNREGISTER, dev);
  		}
  	}
  unlock:
  	rtnl_unlock();
  	up_write(&pernet_ops_rwsem);
  	return err;
  }
  EXPORT_SYMBOL(unregister_netdevice_notifier);
  
  /**
   *	call_netdevice_notifiers_info - call all network notifier blocks
   *	@val: value passed unmodified to notifier function
   *	@info: notifier information data
   *
   *	Call all network notifier blocks.  Parameters and return value
   *	are as for raw_notifier_call_chain().
   */
  
  static int call_netdevice_notifiers_info(unsigned long val,
  					 struct netdev_notifier_info *info)
  {
  	ASSERT_RTNL();
  	return raw_notifier_call_chain(&netdev_chain, val, info);
  }
  
  static int call_netdevice_notifiers_extack(unsigned long val,
  					   struct net_device *dev,
  					   struct netlink_ext_ack *extack)
  {
  	struct netdev_notifier_info info = {
  		.dev = dev,
  		.extack = extack,
  	};
  
  	return call_netdevice_notifiers_info(val, &info);
  }
  
  /**
   *	call_netdevice_notifiers - call all network notifier blocks
   *      @val: value passed unmodified to notifier function
   *      @dev: net_device pointer passed unmodified to notifier function
   *
   *	Call all network notifier blocks.  Parameters and return value
   *	are as for raw_notifier_call_chain().
   */
  
  int call_netdevice_notifiers(unsigned long val, struct net_device *dev)
  {
  	return call_netdevice_notifiers_extack(val, dev, NULL);
  }
  EXPORT_SYMBOL(call_netdevice_notifiers);
  
  /**
   *	call_netdevice_notifiers_mtu - call all network notifier blocks
   *	@val: value passed unmodified to notifier function
   *	@dev: net_device pointer passed unmodified to notifier function
   *	@arg: additional u32 argument passed to the notifier function
   *
   *	Call all network notifier blocks.  Parameters and return value
   *	are as for raw_notifier_call_chain().
   */
  static int call_netdevice_notifiers_mtu(unsigned long val,
  					struct net_device *dev, u32 arg)
  {
  	struct netdev_notifier_info_ext info = {
  		.info.dev = dev,
  		.ext.mtu = arg,
  	};
  
  	BUILD_BUG_ON(offsetof(struct netdev_notifier_info_ext, info) != 0);
  
  	return call_netdevice_notifiers_info(val, &info.info);
  }
  
  #ifdef CONFIG_NET_INGRESS
  static DEFINE_STATIC_KEY_FALSE(ingress_needed_key);
  
  void net_inc_ingress_queue(void)
  {
  	static_branch_inc(&ingress_needed_key);
  }
  EXPORT_SYMBOL_GPL(net_inc_ingress_queue);
  
  void net_dec_ingress_queue(void)
  {
  	static_branch_dec(&ingress_needed_key);
  }
  EXPORT_SYMBOL_GPL(net_dec_ingress_queue);
  #endif
  
  #ifdef CONFIG_NET_EGRESS
  static DEFINE_STATIC_KEY_FALSE(egress_needed_key);
  
  void net_inc_egress_queue(void)
  {
  	static_branch_inc(&egress_needed_key);
  }
  EXPORT_SYMBOL_GPL(net_inc_egress_queue);
  
  void net_dec_egress_queue(void)
  {
  	static_branch_dec(&egress_needed_key);
  }
  EXPORT_SYMBOL_GPL(net_dec_egress_queue);
  #endif
  
  static DEFINE_STATIC_KEY_FALSE(netstamp_needed_key);
  #ifdef CONFIG_JUMP_LABEL
  static atomic_t netstamp_needed_deferred;
  static atomic_t netstamp_wanted;
  static void netstamp_clear(struct work_struct *work)
  {
  	int deferred = atomic_xchg(&netstamp_needed_deferred, 0);
  	int wanted;
  
  	wanted = atomic_add_return(deferred, &netstamp_wanted);
  	if (wanted > 0)
  		static_branch_enable(&netstamp_needed_key);
  	else
  		static_branch_disable(&netstamp_needed_key);
  }
  static DECLARE_WORK(netstamp_work, netstamp_clear);
  #endif
  
  void net_enable_timestamp(void)
  {
  #ifdef CONFIG_JUMP_LABEL
  	int wanted;
  
  	while (1) {
  		wanted = atomic_read(&netstamp_wanted);
  		if (wanted <= 0)
  			break;
  		if (atomic_cmpxchg(&netstamp_wanted, wanted, wanted + 1) == wanted)
  			return;
  	}
  	atomic_inc(&netstamp_needed_deferred);
  	schedule_work(&netstamp_work);
  #else
  	static_branch_inc(&netstamp_needed_key);
  #endif
  }
  EXPORT_SYMBOL(net_enable_timestamp);
  
  void net_disable_timestamp(void)
  {
  #ifdef CONFIG_JUMP_LABEL
  	int wanted;
  
  	while (1) {
  		wanted = atomic_read(&netstamp_wanted);
  		if (wanted <= 1)
  			break;
  		if (atomic_cmpxchg(&netstamp_wanted, wanted, wanted - 1) == wanted)
  			return;
  	}
  	atomic_dec(&netstamp_needed_deferred);
  	schedule_work(&netstamp_work);
  #else
  	static_branch_dec(&netstamp_needed_key);
  #endif
  }
  EXPORT_SYMBOL(net_disable_timestamp);
  
  static inline void net_timestamp_set(struct sk_buff *skb)
  {
  	skb->tstamp = 0;
  	if (static_branch_unlikely(&netstamp_needed_key))
  		__net_timestamp(skb);
  }
  
  #define net_timestamp_check(COND, SKB)				\
  	if (static_branch_unlikely(&netstamp_needed_key)) {	\
  		if ((COND) && !(SKB)->tstamp)			\
  			__net_timestamp(SKB);			\
  	}							\
  
  bool is_skb_forwardable(const struct net_device *dev, const struct sk_buff *skb)
  {
  	unsigned int len;
  
  	if (!(dev->flags & IFF_UP))
  		return false;
  
  	len = dev->mtu + dev->hard_header_len + VLAN_HLEN;
  	if (skb->len <= len)
  		return true;
  
  	/* if TSO is enabled, we don't care about the length as the packet
  	 * could be forwarded without being segmented before
  	 */
  	if (skb_is_gso(skb))
  		return true;
  
  	return false;
  }
  EXPORT_SYMBOL_GPL(is_skb_forwardable);
  
  int __dev_forward_skb(struct net_device *dev, struct sk_buff *skb)
  {
  	int ret = ____dev_forward_skb(dev, skb);
  
  	if (likely(!ret)) {
  		skb->protocol = eth_type_trans(skb, dev);
  		skb_postpull_rcsum(skb, eth_hdr(skb), ETH_HLEN);
  	}
  
  	return ret;
  }
  EXPORT_SYMBOL_GPL(__dev_forward_skb);
  
  /**
   * dev_forward_skb - loopback an skb to another netif
   *
   * @dev: destination network device
   * @skb: buffer to forward
   *
   * return values:
   *	NET_RX_SUCCESS	(no congestion)
   *	NET_RX_DROP     (packet was dropped, but freed)
   *
   * dev_forward_skb can be used for injecting an skb from the
   * start_xmit function of one device into the receive queue
   * of another device.
   *
   * The receiving device may be in another namespace, so
   * we have to clear all information in the skb that could
   * impact namespace isolation.
   */
  int dev_forward_skb(struct net_device *dev, struct sk_buff *skb)
  {
  	return __dev_forward_skb(dev, skb) ?: netif_rx_internal(skb);
  }
  EXPORT_SYMBOL_GPL(dev_forward_skb);
  
  static inline int deliver_skb(struct sk_buff *skb,
  			      struct packet_type *pt_prev,
  			      struct net_device *orig_dev)
  {
  	if (unlikely(skb_orphan_frags_rx(skb, GFP_ATOMIC)))
  		return -ENOMEM;
  	refcount_inc(&skb->users);
  	return pt_prev->func(skb, skb->dev, pt_prev, orig_dev);
  }
  
  static inline void deliver_ptype_list_skb(struct sk_buff *skb,
  					  struct packet_type **pt,
  					  struct net_device *orig_dev,
  					  __be16 type,
  					  struct list_head *ptype_list)
  {
  	struct packet_type *ptype, *pt_prev = *pt;
  
  	list_for_each_entry_rcu(ptype, ptype_list, list) {
  		if (ptype->type != type)
  			continue;
  		if (pt_prev)
  			deliver_skb(skb, pt_prev, orig_dev);
  		pt_prev = ptype;
  	}
  	*pt = pt_prev;
  }
  
  static inline bool skb_loop_sk(struct packet_type *ptype, struct sk_buff *skb)
  {
  	if (!ptype->af_packet_priv || !skb->sk)
  		return false;
  
  	if (ptype->id_match)
  		return ptype->id_match(ptype, skb->sk);
  	else if ((struct sock *)ptype->af_packet_priv == skb->sk)
  		return true;
  
  	return false;
  }
  
  /**
   * dev_nit_active - return true if any network interface taps are in use
   *
   * @dev: network device to check for the presence of taps
   */
  bool dev_nit_active(struct net_device *dev)
  {
  	return !list_empty(&ptype_all) || !list_empty(&dev->ptype_all);
  }
  EXPORT_SYMBOL_GPL(dev_nit_active);
  
  /*
   *	Support routine. Sends outgoing frames to any network
   *	taps currently in use.
   */
  
  void dev_queue_xmit_nit(struct sk_buff *skb, struct net_device *dev)
  {
  	struct packet_type *ptype;
  	struct sk_buff *skb2 = NULL;
  	struct packet_type *pt_prev = NULL;
  	struct list_head *ptype_list = &ptype_all;
  
  	rcu_read_lock();
  again:
  	list_for_each_entry_rcu(ptype, ptype_list, list) {
  		if (ptype->ignore_outgoing)
  			continue;
  
  		/* Never send packets back to the socket
  		 * they originated from - MvS (miquels@drinkel.ow.org)
  		 */
  		if (skb_loop_sk(ptype, skb))
  			continue;
  
  		if (pt_prev) {
  			deliver_skb(skb2, pt_prev, skb->dev);
  			pt_prev = ptype;
  			continue;
  		}
  
  		/* need to clone skb, done only once */
  		skb2 = skb_clone(skb, GFP_ATOMIC);
  		if (!skb2)
  			goto out_unlock;
  
  		net_timestamp_set(skb2);
  
  		/* skb->nh should be correctly
  		 * set by sender, so that the second statement is
  		 * just protection against buggy protocols.
  		 */
  		skb_reset_mac_header(skb2);
  
  		if (skb_network_header(skb2) < skb2->data ||
  		    skb_network_header(skb2) > skb_tail_pointer(skb2)) {
  			net_crit_ratelimited("protocol %04x is buggy, dev %s\n",
  					     ntohs(skb2->protocol),
  					     dev->name);
  			skb_reset_network_header(skb2);
  		}
  
  		skb2->transport_header = skb2->network_header;
  		skb2->pkt_type = PACKET_OUTGOING;
  		pt_prev = ptype;
  	}
  
  	if (ptype_list == &ptype_all) {
  		ptype_list = &dev->ptype_all;
  		goto again;
  	}
  out_unlock:
  	if (pt_prev) {
  		if (!skb_orphan_frags_rx(skb2, GFP_ATOMIC))
  			pt_prev->func(skb2, skb->dev, pt_prev, skb->dev);
  		else
  			kfree_skb(skb2);
  	}
  	rcu_read_unlock();
  }
  EXPORT_SYMBOL_GPL(dev_queue_xmit_nit);
  
  /**
   * netif_setup_tc - Handle tc mappings on real_num_tx_queues change
   * @dev: Network device
   * @txq: number of queues available
   *
   * If real_num_tx_queues is changed the tc mappings may no longer be
   * valid. To resolve this verify the tc mapping remains valid and if
   * not NULL the mapping. With no priorities mapping to this
   * offset/count pair it will no longer be used. In the worst case TC0
   * is invalid nothing can be done so disable priority mappings. If is
   * expected that drivers will fix this mapping if they can before
   * calling netif_set_real_num_tx_queues.
   */
  static void netif_setup_tc(struct net_device *dev, unsigned int txq)
  {
  	int i;
  	struct netdev_tc_txq *tc = &dev->tc_to_txq[0];
  
  	/* If TC0 is invalidated disable TC mapping */
  	if (tc->offset + tc->count > txq) {
  		pr_warn("Number of in use tx queues changed invalidating tc mappings. Priority traffic classification disabled!\n");
  		dev->num_tc = 0;
  		return;
  	}
  
  	/* Invalidated prio to tc mappings set to TC0 */
  	for (i = 1; i < TC_BITMASK + 1; i++) {
  		int q = netdev_get_prio_tc_map(dev, i);
  
  		tc = &dev->tc_to_txq[q];
  		if (tc->offset + tc->count > txq) {
  			pr_warn("Number of in use tx queues changed. Priority %i to tc mapping %i is no longer valid. Setting map to 0\n",
  				i, q);
  			netdev_set_prio_tc_map(dev, i, 0);
  		}
  	}
  }
  
  int netdev_txq_to_tc(struct net_device *dev, unsigned int txq)
  {
  	if (dev->num_tc) {
  		struct netdev_tc_txq *tc = &dev->tc_to_txq[0];
  		int i;
  
  		/* walk through the TCs and see if it falls into any of them */
  		for (i = 0; i < TC_MAX_QUEUE; i++, tc++) {
  			if ((txq - tc->offset) < tc->count)
  				return i;
  		}
  
  		/* didn't find it, just return -1 to indicate no match */
  		return -1;
  	}
  
  	return 0;
  }
  EXPORT_SYMBOL(netdev_txq_to_tc);
  
  #ifdef CONFIG_XPS
  struct static_key xps_needed __read_mostly;
  EXPORT_SYMBOL(xps_needed);
  struct static_key xps_rxqs_needed __read_mostly;
  EXPORT_SYMBOL(xps_rxqs_needed);
  static DEFINE_MUTEX(xps_map_mutex);
  #define xmap_dereference(P)		\
  	rcu_dereference_protected((P), lockdep_is_held(&xps_map_mutex))
  
  static bool remove_xps_queue(struct xps_dev_maps *dev_maps,
  			     int tci, u16 index)
  {
  	struct xps_map *map = NULL;
  	int pos;
  
  	if (dev_maps)
  		map = xmap_dereference(dev_maps->attr_map[tci]);
  	if (!map)
  		return false;
  
  	for (pos = map->len; pos--;) {
  		if (map->queues[pos] != index)
  			continue;
  
  		if (map->len > 1) {
  			map->queues[pos] = map->queues[--map->len];
  			break;
  		}
  
  		RCU_INIT_POINTER(dev_maps->attr_map[tci], NULL);
  		kfree_rcu(map, rcu);
  		return false;
  	}
  
  	return true;
  }
  
  static bool remove_xps_queue_cpu(struct net_device *dev,
  				 struct xps_dev_maps *dev_maps,
  				 int cpu, u16 offset, u16 count)
  {
  	int num_tc = dev->num_tc ? : 1;
  	bool active = false;
  	int tci;
  
  	for (tci = cpu * num_tc; num_tc--; tci++) {
  		int i, j;
  
  		for (i = count, j = offset; i--; j++) {
  			if (!remove_xps_queue(dev_maps, tci, j))
  				break;
  		}
  
  		active |= i < 0;
  	}
  
  	return active;
  }
  
  static void reset_xps_maps(struct net_device *dev,
  			   struct xps_dev_maps *dev_maps,
  			   bool is_rxqs_map)
  {
  	if (is_rxqs_map) {
  		static_key_slow_dec_cpuslocked(&xps_rxqs_needed);
  		RCU_INIT_POINTER(dev->xps_rxqs_map, NULL);
  	} else {
  		RCU_INIT_POINTER(dev->xps_cpus_map, NULL);
  	}
  	static_key_slow_dec_cpuslocked(&xps_needed);
  	kfree_rcu(dev_maps, rcu);
  }
  
  static void clean_xps_maps(struct net_device *dev, const unsigned long *mask,
  			   struct xps_dev_maps *dev_maps, unsigned int nr_ids,
  			   u16 offset, u16 count, bool is_rxqs_map)
  {
  	bool active = false;
  	int i, j;
  
  	for (j = -1; j = netif_attrmask_next(j, mask, nr_ids),
  	     j < nr_ids;)
  		active |= remove_xps_queue_cpu(dev, dev_maps, j, offset,
  					       count);
  	if (!active)
  		reset_xps_maps(dev, dev_maps, is_rxqs_map);
  
  	if (!is_rxqs_map) {
  		for (i = offset + (count - 1); count--; i--) {
  			netdev_queue_numa_node_write(
  				netdev_get_tx_queue(dev, i),
  				NUMA_NO_NODE);
  		}
  	}
  }
  
  static void netif_reset_xps_queues(struct net_device *dev, u16 offset,
  				   u16 count)
  {
  	const unsigned long *possible_mask = NULL;
  	struct xps_dev_maps *dev_maps;
  	unsigned int nr_ids;
  
  	if (!static_key_false(&xps_needed))
  		return;
  
  	cpus_read_lock();
  	mutex_lock(&xps_map_mutex);
  
  	if (static_key_false(&xps_rxqs_needed)) {
  		dev_maps = xmap_dereference(dev->xps_rxqs_map);
  		if (dev_maps) {
  			nr_ids = dev->num_rx_queues;
  			clean_xps_maps(dev, possible_mask, dev_maps, nr_ids,
  				       offset, count, true);
  		}
  	}
  
  	dev_maps = xmap_dereference(dev->xps_cpus_map);
  	if (!dev_maps)
  		goto out_no_maps;
  
  	if (num_possible_cpus() > 1)
  		possible_mask = cpumask_bits(cpu_possible_mask);
  	nr_ids = nr_cpu_ids;
  	clean_xps_maps(dev, possible_mask, dev_maps, nr_ids, offset, count,
  		       false);
  
  out_no_maps:
  	mutex_unlock(&xps_map_mutex);
  	cpus_read_unlock();
  }
  
  static void netif_reset_xps_queues_gt(struct net_device *dev, u16 index)
  {
  	netif_reset_xps_queues(dev, index, dev->num_tx_queues - index);
  }
  
  static struct xps_map *expand_xps_map(struct xps_map *map, int attr_index,
  				      u16 index, bool is_rxqs_map)
  {
  	struct xps_map *new_map;
  	int alloc_len = XPS_MIN_MAP_ALLOC;
  	int i, pos;
  
  	for (pos = 0; map && pos < map->len; pos++) {
  		if (map->queues[pos] != index)
  			continue;
  		return map;
  	}
  
  	/* Need to add tx-queue to this CPU's/rx-queue's existing map */
  	if (map) {
  		if (pos < map->alloc_len)
  			return map;
  
  		alloc_len = map->alloc_len * 2;
  	}
  
  	/* Need to allocate new map to store tx-queue on this CPU's/rx-queue's
  	 *  map
  	 */
  	if (is_rxqs_map)
  		new_map = kzalloc(XPS_MAP_SIZE(alloc_len), GFP_KERNEL);
  	else
  		new_map = kzalloc_node(XPS_MAP_SIZE(alloc_len), GFP_KERNEL,
  				       cpu_to_node(attr_index));
  	if (!new_map)
  		return NULL;
  
  	for (i = 0; i < pos; i++)
  		new_map->queues[i] = map->queues[i];
  	new_map->alloc_len = alloc_len;
  	new_map->len = pos;
  
  	return new_map;
  }
  
  /* Must be called under cpus_read_lock */
  int __netif_set_xps_queue(struct net_device *dev, const unsigned long *mask,
  			  u16 index, bool is_rxqs_map)
  {
  	const unsigned long *online_mask = NULL, *possible_mask = NULL;
  	struct xps_dev_maps *dev_maps, *new_dev_maps = NULL;
  	int i, j, tci, numa_node_id = -2;
  	int maps_sz, num_tc = 1, tc = 0;
  	struct xps_map *map, *new_map;
  	bool active = false;
  	unsigned int nr_ids;
  
  	if (dev->num_tc) {
  		/* Do not allow XPS on subordinate device directly */
  		num_tc = dev->num_tc;
  		if (num_tc < 0)
  			return -EINVAL;
  
  		/* If queue belongs to subordinate dev use its map */
  		dev = netdev_get_tx_queue(dev, index)->sb_dev ? : dev;
  
  		tc = netdev_txq_to_tc(dev, index);
  		if (tc < 0)
  			return -EINVAL;
  	}
  
  	mutex_lock(&xps_map_mutex);
  	if (is_rxqs_map) {
  		maps_sz = XPS_RXQ_DEV_MAPS_SIZE(num_tc, dev->num_rx_queues);
  		dev_maps = xmap_dereference(dev->xps_rxqs_map);
  		nr_ids = dev->num_rx_queues;
  	} else {
  		maps_sz = XPS_CPU_DEV_MAPS_SIZE(num_tc);
  		if (num_possible_cpus() > 1) {
  			online_mask = cpumask_bits(cpu_online_mask);
  			possible_mask = cpumask_bits(cpu_possible_mask);
  		}
  		dev_maps = xmap_dereference(dev->xps_cpus_map);
  		nr_ids = nr_cpu_ids;
  	}
  
  	if (maps_sz < L1_CACHE_BYTES)
  		maps_sz = L1_CACHE_BYTES;
  
  	/* allocate memory for queue storage */
  	for (j = -1; j = netif_attrmask_next_and(j, online_mask, mask, nr_ids),
  	     j < nr_ids;) {
  		if (!new_dev_maps)
  			new_dev_maps = kzalloc(maps_sz, GFP_KERNEL);
  		if (!new_dev_maps) {
  			mutex_unlock(&xps_map_mutex);
  			return -ENOMEM;
  		}
  
  		tci = j * num_tc + tc;
  		map = dev_maps ? xmap_dereference(dev_maps->attr_map[tci]) :
  				 NULL;
  
  		map = expand_xps_map(map, j, index, is_rxqs_map);
  		if (!map)
  			goto error;
  
  		RCU_INIT_POINTER(new_dev_maps->attr_map[tci], map);
  	}
  
  	if (!new_dev_maps)
  		goto out_no_new_maps;
  
  	if (!dev_maps) {
  		/* Increment static keys at most once per type */
  		static_key_slow_inc_cpuslocked(&xps_needed);
  		if (is_rxqs_map)
  			static_key_slow_inc_cpuslocked(&xps_rxqs_needed);
  	}
  
  	for (j = -1; j = netif_attrmask_next(j, possible_mask, nr_ids),
  	     j < nr_ids;) {
  		/* copy maps belonging to foreign traffic classes */
  		for (i = tc, tci = j * num_tc; dev_maps && i--; tci++) {
  			/* fill in the new device map from the old device map */
  			map = xmap_dereference(dev_maps->attr_map[tci]);
  			RCU_INIT_POINTER(new_dev_maps->attr_map[tci], map);
  		}
  
  		/* We need to explicitly update tci as prevous loop
  		 * could break out early if dev_maps is NULL.
  		 */
  		tci = j * num_tc + tc;
  
  		if (netif_attr_test_mask(j, mask, nr_ids) &&
  		    netif_attr_test_online(j, online_mask, nr_ids)) {
  			/* add tx-queue to CPU/rx-queue maps */
  			int pos = 0;
  
  			map = xmap_dereference(new_dev_maps->attr_map[tci]);
  			while ((pos < map->len) && (map->queues[pos] != index))
  				pos++;
  
  			if (pos == map->len)
  				map->queues[map->len++] = index;
  #ifdef CONFIG_NUMA
  			if (!is_rxqs_map) {
  				if (numa_node_id == -2)
  					numa_node_id = cpu_to_node(j);
  				else if (numa_node_id != cpu_to_node(j))
  					numa_node_id = -1;
  			}
  #endif
  		} else if (dev_maps) {
  			/* fill in the new device map from the old device map */
  			map = xmap_dereference(dev_maps->attr_map[tci]);
  			RCU_INIT_POINTER(new_dev_maps->attr_map[tci], map);
  		}
  
  		/* copy maps belonging to foreign traffic classes */
  		for (i = num_tc - tc, tci++; dev_maps && --i; tci++) {
  			/* fill in the new device map from the old device map */
  			map = xmap_dereference(dev_maps->attr_map[tci]);
  			RCU_INIT_POINTER(new_dev_maps->attr_map[tci], map);
  		}
  	}
  
  	if (is_rxqs_map)
  		rcu_assign_pointer(dev->xps_rxqs_map, new_dev_maps);
  	else
  		rcu_assign_pointer(dev->xps_cpus_map, new_dev_maps);
  
  	/* Cleanup old maps */
  	if (!dev_maps)
  		goto out_no_old_maps;
  
  	for (j = -1; j = netif_attrmask_next(j, possible_mask, nr_ids),
  	     j < nr_ids;) {
  		for (i = num_tc, tci = j * num_tc; i--; tci++) {
  			new_map = xmap_dereference(new_dev_maps->attr_map[tci]);
  			map = xmap_dereference(dev_maps->attr_map[tci]);
  			if (map && map != new_map)
  				kfree_rcu(map, rcu);
  		}
  	}
  
  	kfree_rcu(dev_maps, rcu);
  
  out_no_old_maps:
  	dev_maps = new_dev_maps;
  	active = true;
  
  out_no_new_maps:
  	if (!is_rxqs_map) {
  		/* update Tx queue numa node */
  		netdev_queue_numa_node_write(netdev_get_tx_queue(dev, index),
  					     (numa_node_id >= 0) ?
  					     numa_node_id : NUMA_NO_NODE);
  	}
  
  	if (!dev_maps)
  		goto out_no_maps;
  
  	/* removes tx-queue from unused CPUs/rx-queues */
  	for (j = -1; j = netif_attrmask_next(j, possible_mask, nr_ids),
  	     j < nr_ids;) {
  		for (i = tc, tci = j * num_tc; i--; tci++)
  			active |= remove_xps_queue(dev_maps, tci, index);
  		if (!netif_attr_test_mask(j, mask, nr_ids) ||
  		    !netif_attr_test_online(j, online_mask, nr_ids))
  			active |= remove_xps_queue(dev_maps, tci, index);
  		for (i = num_tc - tc, tci++; --i; tci++)
  			active |= remove_xps_queue(dev_maps, tci, index);
  	}
  
  	/* free map if not active */
  	if (!active)
  		reset_xps_maps(dev, dev_maps, is_rxqs_map);
  
  out_no_maps:
  	mutex_unlock(&xps_map_mutex);
  
  	return 0;
  error:
  	/* remove any maps that we added */
  	for (j = -1; j = netif_attrmask_next(j, possible_mask, nr_ids),
  	     j < nr_ids;) {
  		for (i = num_tc, tci = j * num_tc; i--; tci++) {
  			new_map = xmap_dereference(new_dev_maps->attr_map[tci]);
  			map = dev_maps ?
  			      xmap_dereference(dev_maps->attr_map[tci]) :
  			      NULL;
  			if (new_map && new_map != map)
  				kfree(new_map);
  		}
  	}
  
  	mutex_unlock(&xps_map_mutex);
  
  	kfree(new_dev_maps);
  	return -ENOMEM;
  }
  EXPORT_SYMBOL_GPL(__netif_set_xps_queue);
  
  int netif_set_xps_queue(struct net_device *dev, const struct cpumask *mask,
  			u16 index)
  {
  	int ret;
  
  	cpus_read_lock();
  	ret =  __netif_set_xps_queue(dev, cpumask_bits(mask), index, false);
  	cpus_read_unlock();
  
  	return ret;
  }
  EXPORT_SYMBOL(netif_set_xps_queue);
  
  #endif
  static void netdev_unbind_all_sb_channels(struct net_device *dev)
  {
  	struct netdev_queue *txq = &dev->_tx[dev->num_tx_queues];
  
  	/* Unbind any subordinate channels */
  	while (txq-- != &dev->_tx[0]) {
  		if (txq->sb_dev)
  			netdev_unbind_sb_channel(dev, txq->sb_dev);
  	}
  }
  
  void netdev_reset_tc(struct net_device *dev)
  {
  #ifdef CONFIG_XPS
  	netif_reset_xps_queues_gt(dev, 0);
  #endif
  	netdev_unbind_all_sb_channels(dev);
  
  	/* Reset TC configuration of device */
  	dev->num_tc = 0;
  	memset(dev->tc_to_txq, 0, sizeof(dev->tc_to_txq));
  	memset(dev->prio_tc_map, 0, sizeof(dev->prio_tc_map));
  }
  EXPORT_SYMBOL(netdev_reset_tc);
  
  int netdev_set_tc_queue(struct net_device *dev, u8 tc, u16 count, u16 offset)
  {
  	if (tc >= dev->num_tc)
  		return -EINVAL;
  
  #ifdef CONFIG_XPS
  	netif_reset_xps_queues(dev, offset, count);
  #endif
  	dev->tc_to_txq[tc].count = count;
  	dev->tc_to_txq[tc].offset = offset;
  	return 0;
  }
  EXPORT_SYMBOL(netdev_set_tc_queue);
  
  int netdev_set_num_tc(struct net_device *dev, u8 num_tc)
  {
  	if (num_tc > TC_MAX_QUEUE)
  		return -EINVAL;
  
  #ifdef CONFIG_XPS
  	netif_reset_xps_queues_gt(dev, 0);
  #endif
  	netdev_unbind_all_sb_channels(dev);
  
  	dev->num_tc = num_tc;
  	return 0;
  }
  EXPORT_SYMBOL(netdev_set_num_tc);
  
  void netdev_unbind_sb_channel(struct net_device *dev,
  			      struct net_device *sb_dev)
  {
  	struct netdev_queue *txq = &dev->_tx[dev->num_tx_queues];
  
  #ifdef CONFIG_XPS
  	netif_reset_xps_queues_gt(sb_dev, 0);
  #endif
  	memset(sb_dev->tc_to_txq, 0, sizeof(sb_dev->tc_to_txq));
  	memset(sb_dev->prio_tc_map, 0, sizeof(sb_dev->prio_tc_map));
  
  	while (txq-- != &dev->_tx[0]) {
  		if (txq->sb_dev == sb_dev)
  			txq->sb_dev = NULL;
  	}
  }
  EXPORT_SYMBOL(netdev_unbind_sb_channel);
  
  int netdev_bind_sb_channel_queue(struct net_device *dev,
  				 struct net_device *sb_dev,
  				 u8 tc, u16 count, u16 offset)
  {
  	/* Make certain the sb_dev and dev are already configured */
  	if (sb_dev->num_tc >= 0 || tc >= dev->num_tc)
  		return -EINVAL;
  
  	/* We cannot hand out queues we don't have */
  	if ((offset + count) > dev->real_num_tx_queues)
  		return -EINVAL;
  
  	/* Record the mapping */
  	sb_dev->tc_to_txq[tc].count = count;
  	sb_dev->tc_to_txq[tc].offset = offset;
  
  	/* Provide a way for Tx queue to find the tc_to_txq map or
  	 * XPS map for itself.
  	 */
  	while (count--)
  		netdev_get_tx_queue(dev, count + offset)->sb_dev = sb_dev;
  
  	return 0;
  }
  EXPORT_SYMBOL(netdev_bind_sb_channel_queue);
  
  int netdev_set_sb_channel(struct net_device *dev, u16 channel)
  {
  	/* Do not use a multiqueue device to represent a subordinate channel */
  	if (netif_is_multiqueue(dev))
  		return -ENODEV;
  
  	/* We allow channels 1 - 32767 to be used for subordinate channels.
  	 * Channel 0 is meant to be "native" mode and used only to represent
  	 * the main root device. We allow writing 0 to reset the device back
  	 * to normal mode after being used as a subordinate channel.
  	 */
  	if (channel > S16_MAX)
  		return -EINVAL;
  
  	dev->num_tc = -channel;
  
  	return 0;
  }
  EXPORT_SYMBOL(netdev_set_sb_channel);
  
  /*
   * Routine to help set real_num_tx_queues. To avoid skbs mapped to queues
   * greater than real_num_tx_queues stale skbs on the qdisc must be flushed.
   */
  int netif_set_real_num_tx_queues(struct net_device *dev, unsigned int txq)
  {
  	bool disabling;
  	int rc;
  
  	disabling = txq < dev->real_num_tx_queues;
  
  	if (txq < 1 || txq > dev->num_tx_queues)
  		return -EINVAL;
  
  	if (dev->reg_state == NETREG_REGISTERED ||
  	    dev->reg_state == NETREG_UNREGISTERING) {
  		ASSERT_RTNL();
  
  		rc = netdev_queue_update_kobjects(dev, dev->real_num_tx_queues,
  						  txq);
  		if (rc)
  			return rc;
  
  		if (dev->num_tc)
  			netif_setup_tc(dev, txq);
  
  		dev->real_num_tx_queues = txq;
  
  		if (disabling) {
  			synchronize_net();
  			qdisc_reset_all_tx_gt(dev, txq);
  #ifdef CONFIG_XPS
  			netif_reset_xps_queues_gt(dev, txq);
  #endif
  		}
  	} else {
  		dev->real_num_tx_queues = txq;
  	}
  
  	return 0;
  }
  EXPORT_SYMBOL(netif_set_real_num_tx_queues);
  
  #ifdef CONFIG_SYSFS
  /**
   *	netif_set_real_num_rx_queues - set actual number of RX queues used
   *	@dev: Network device
   *	@rxq: Actual number of RX queues
   *
   *	This must be called either with the rtnl_lock held or before
   *	registration of the net device.  Returns 0 on success, or a
   *	negative error code.  If called before registration, it always
   *	succeeds.
   */
  int netif_set_real_num_rx_queues(struct net_device *dev, unsigned int rxq)
  {
  	int rc;
  
  	if (rxq < 1 || rxq > dev->num_rx_queues)
  		return -EINVAL;
  
  	if (dev->reg_state == NETREG_REGISTERED) {
  		ASSERT_RTNL();
  
  		rc = net_rx_queue_update_kobjects(dev, dev->real_num_rx_queues,
  						  rxq);
  		if (rc)
  			return rc;
  	}
  
  	dev->real_num_rx_queues = rxq;
  	return 0;
  }
  EXPORT_SYMBOL(netif_set_real_num_rx_queues);
  #endif
  
  /**
   * netif_get_num_default_rss_queues - default number of RSS queues
   *
   * This routine should set an upper limit on the number of RSS queues
   * used by default by multiqueue devices.
   */
  int netif_get_num_default_rss_queues(void)
  {
  	return is_kdump_kernel() ?
  		1 : min_t(int, DEFAULT_MAX_NUM_RSS_QUEUES, num_online_cpus());
  }
  EXPORT_SYMBOL(netif_get_num_default_rss_queues);
  
  static void __netif_reschedule(struct Qdisc *q)
  {
  	struct softnet_data *sd;
  	unsigned long flags;
  
  	local_irq_save(flags);
  	sd = this_cpu_ptr(&softnet_data);
  	q->next_sched = NULL;
  	*sd->output_queue_tailp = q;
  	sd->output_queue_tailp = &q->next_sched;
  	raise_softirq_irqoff(NET_TX_SOFTIRQ);
  	local_irq_restore(flags);
  }
  
  void __netif_schedule(struct Qdisc *q)
  {
  	if (!test_and_set_bit(__QDISC_STATE_SCHED, &q->state))
  		__netif_reschedule(q);
  }
  EXPORT_SYMBOL(__netif_schedule);
  
  struct dev_kfree_skb_cb {
  	enum skb_free_reason reason;
  };
  
  static struct dev_kfree_skb_cb *get_kfree_skb_cb(const struct sk_buff *skb)
  {
  	return (struct dev_kfree_skb_cb *)skb->cb;
  }
  
  void netif_schedule_queue(struct netdev_queue *txq)
  {
  	rcu_read_lock();
  	if (!(txq->state & QUEUE_STATE_ANY_XOFF)) {
  		struct Qdisc *q = rcu_dereference(txq->qdisc);
  
  		__netif_schedule(q);
  	}
  	rcu_read_unlock();
  }
  EXPORT_SYMBOL(netif_schedule_queue);
  
  void netif_tx_wake_queue(struct netdev_queue *dev_queue)
  {
  	if (test_and_clear_bit(__QUEUE_STATE_DRV_XOFF, &dev_queue->state)) {
  		struct Qdisc *q;
  
  		rcu_read_lock();
  		q = rcu_dereference(dev_queue->qdisc);
  		__netif_schedule(q);
  		rcu_read_unlock();
  	}
  }
  EXPORT_SYMBOL(netif_tx_wake_queue);
  
  void __dev_kfree_skb_irq(struct sk_buff *skb, enum skb_free_reason reason)
  {
  	unsigned long flags;
  
  	if (unlikely(!skb))
  		return;
  
  	if (likely(refcount_read(&skb->users) == 1)) {
  		smp_rmb();
  		refcount_set(&skb->users, 0);
  	} else if (likely(!refcount_dec_and_test(&skb->users))) {
  		return;
  	}
  	get_kfree_skb_cb(skb)->reason = reason;
  	local_irq_save(flags);
  	skb->next = __this_cpu_read(softnet_data.completion_queue);
  	__this_cpu_write(softnet_data.completion_queue, skb);
  	raise_softirq_irqoff(NET_TX_SOFTIRQ);
  	local_irq_restore(flags);
  }
  EXPORT_SYMBOL(__dev_kfree_skb_irq);
  
  void __dev_kfree_skb_any(struct sk_buff *skb, enum skb_free_reason reason)
  {
  	if (in_irq() || irqs_disabled())
  		__dev_kfree_skb_irq(skb, reason);
  	else
  		dev_kfree_skb(skb);
  }
  EXPORT_SYMBOL(__dev_kfree_skb_any);
  
  
  /**
   * netif_device_detach - mark device as removed
   * @dev: network device
   *
   * Mark device as removed from system and therefore no longer available.
   */
  void netif_device_detach(struct net_device *dev)
  {
  	if (test_and_clear_bit(__LINK_STATE_PRESENT, &dev->state) &&
  	    netif_running(dev)) {
  		netif_tx_stop_all_queues(dev);
  	}
  }
  EXPORT_SYMBOL(netif_device_detach);
  
  /**
   * netif_device_attach - mark device as attached
   * @dev: network device
   *
   * Mark device as attached from system and restart if needed.
   */
  void netif_device_attach(struct net_device *dev)
  {
  	if (!test_and_set_bit(__LINK_STATE_PRESENT, &dev->state) &&
  	    netif_running(dev)) {
  		netif_tx_wake_all_queues(dev);
  		__netdev_watchdog_up(dev);
  	}
  }
  EXPORT_SYMBOL(netif_device_attach);
  
  /*
   * Returns a Tx hash based on the given packet descriptor a Tx queues' number
   * to be used as a distribution range.
   */
  static u16 skb_tx_hash(const struct net_device *dev,
  		       const struct net_device *sb_dev,
  		       struct sk_buff *skb)
  {
  	u32 hash;
  	u16 qoffset = 0;
  	u16 qcount = dev->real_num_tx_queues;
  
  	if (dev->num_tc) {
  		u8 tc = netdev_get_prio_tc_map(dev, skb->priority);
  
  		qoffset = sb_dev->tc_to_txq[tc].offset;
  		qcount = sb_dev->tc_to_txq[tc].count;
  	}
  
  	if (skb_rx_queue_recorded(skb)) {
  		hash = skb_get_rx_queue(skb);
  		if (hash >= qoffset)
  			hash -= qoffset;
  		while (unlikely(hash >= qcount))
  			hash -= qcount;
  		return hash + qoffset;
  	}
  
  	return (u16) reciprocal_scale(skb_get_hash(skb), qcount) + qoffset;
  }
  
  static void skb_warn_bad_offload(const struct sk_buff *skb)
  {
  	static const netdev_features_t null_features;
  	struct net_device *dev = skb->dev;
  	const char *name = "";
  
  	if (!net_ratelimit())
  		return;
  
  	if (dev) {
  		if (dev->dev.parent)
  			name = dev_driver_string(dev->dev.parent);
  		else
  			name = netdev_name(dev);
  	}
  	skb_dump(KERN_WARNING, skb, false);
  	WARN(1, "%s: caps=(%pNF, %pNF)\n",
  	     name, dev ? &dev->features : &null_features,
  	     skb->sk ? &skb->sk->sk_route_caps : &null_features);
  }
  
  /*
   * Invalidate hardware checksum when packet is to be mangled, and
   * complete checksum manually on outgoing path.
   */
  int skb_checksum_help(struct sk_buff *skb)
  {
  	__wsum csum;
  	int ret = 0, offset;
  
  	if (skb->ip_summed == CHECKSUM_COMPLETE)
  		goto out_set_summed;
  
  	if (unlikely(skb_shinfo(skb)->gso_size)) {
  		skb_warn_bad_offload(skb);
  		return -EINVAL;
  	}
  
  	/* Before computing a checksum, we should make sure no frag could
  	 * be modified by an external entity : checksum could be wrong.
  	 */
  	if (skb_has_shared_frag(skb)) {
  		ret = __skb_linearize(skb);
  		if (ret)
  			goto out;
  	}
  
  	offset = skb_checksum_start_offset(skb);
  	BUG_ON(offset >= skb_headlen(skb));
  	csum = skb_checksum(skb, offset, skb->len - offset, 0);
  
  	offset += skb->csum_offset;
  	BUG_ON(offset + sizeof(__sum16) > skb_headlen(skb));
  
  	if (skb_cloned(skb) &&
  	    !skb_clone_writable(skb, offset + sizeof(__sum16))) {
  		ret = pskb_expand_head(skb, 0, 0, GFP_ATOMIC);
  		if (ret)
  			goto out;
  	}
  
  	*(__sum16 *)(skb->data + offset) = csum_fold(csum) ?: CSUM_MANGLED_0;
  out_set_summed:
  	skb->ip_summed = CHECKSUM_NONE;
  out:
  	return ret;
  }
  EXPORT_SYMBOL(skb_checksum_help);
  
  int skb_crc32c_csum_help(struct sk_buff *skb)
  {
  	__le32 crc32c_csum;
  	int ret = 0, offset, start;
  
  	if (skb->ip_summed != CHECKSUM_PARTIAL)
  		goto out;
  
  	if (unlikely(skb_is_gso(skb)))
  		goto out;
  
  	/* Before computing a checksum, we should make sure no frag could
  	 * be modified by an external entity : checksum could be wrong.
  	 */
  	if (unlikely(skb_has_shared_frag(skb))) {
  		ret = __skb_linearize(skb);
  		if (ret)
  			goto out;
  	}
  	start = skb_checksum_start_offset(skb);
  	offset = start + offsetof(struct sctphdr, checksum);
  	if (WARN_ON_ONCE(offset >= skb_headlen(skb))) {
  		ret = -EINVAL;
  		goto out;
  	}
  	if (skb_cloned(skb) &&
  	    !skb_clone_writable(skb, offset + sizeof(__le32))) {
  		ret = pskb_expand_head(skb, 0, 0, GFP_ATOMIC);
  		if (ret)
  			goto out;
  	}
  	crc32c_csum = cpu_to_le32(~__skb_checksum(skb, start,
  						  skb->len - start, ~(__u32)0,
  						  crc32c_csum_stub));
  	*(__le32 *)(skb->data + offset) = crc32c_csum;
  	skb->ip_summed = CHECKSUM_NONE;
  	skb->csum_not_inet = 0;
  out:
  	return ret;
  }
  
  __be16 skb_network_protocol(struct sk_buff *skb, int *depth)
  {
  	__be16 type = skb->protocol;
  
  	/* Tunnel gso handlers can set protocol to ethernet. */
  	if (type == htons(ETH_P_TEB)) {
  		struct ethhdr *eth;
  
  		if (unlikely(!pskb_may_pull(skb, sizeof(struct ethhdr))))
  			return 0;
  
  		eth = (struct ethhdr *)skb->data;
  		type = eth->h_proto;
  	}
  
  	return __vlan_get_protocol(skb, type, depth);
  }
  
  /**
   *	skb_mac_gso_segment - mac layer segmentation handler.
   *	@skb: buffer to segment
   *	@features: features for the output path (see dev->features)
   */
  struct sk_buff *skb_mac_gso_segment(struct sk_buff *skb,
  				    netdev_features_t features)
  {
  	struct sk_buff *segs = ERR_PTR(-EPROTONOSUPPORT);
  	struct packet_offload *ptype;
  	int vlan_depth = skb->mac_len;
  	__be16 type = skb_network_protocol(skb, &vlan_depth);
  
  	if (unlikely(!type))
  		return ERR_PTR(-EINVAL);
  
  	__skb_pull(skb, vlan_depth);
  
  	rcu_read_lock();
  	list_for_each_entry_rcu(ptype, &offload_base, list) {
  		if (ptype->type == type && ptype->callbacks.gso_segment) {
  			segs = ptype->callbacks.gso_segment(skb, features);
  			break;
  		}
  	}
  	rcu_read_unlock();
  
  	__skb_push(skb, skb->data - skb_mac_header(skb));
  
  	return segs;
  }
  EXPORT_SYMBOL(skb_mac_gso_segment);
  
  
  /* openvswitch calls this on rx path, so we need a different check.
   */
  static inline bool skb_needs_check(struct sk_buff *skb, bool tx_path)
  {
  	if (tx_path)
  		return skb->ip_summed != CHECKSUM_PARTIAL &&
  		       skb->ip_summed != CHECKSUM_UNNECESSARY;
  
  	return skb->ip_summed == CHECKSUM_NONE;
  }
  
  /**
   *	__skb_gso_segment - Perform segmentation on skb.
   *	@skb: buffer to segment
   *	@features: features for the output path (see dev->features)
   *	@tx_path: whether it is called in TX path
   *
   *	This function segments the given skb and returns a list of segments.
   *
   *	It may return NULL if the skb requires no segmentation.  This is
   *	only possible when GSO is used for verifying header integrity.
   *
   *	Segmentation preserves SKB_SGO_CB_OFFSET bytes of previous skb cb.
   */
  struct sk_buff *__skb_gso_segment(struct sk_buff *skb,
  				  netdev_features_t features, bool tx_path)
  {
  	struct sk_buff *segs;
  
  	if (unlikely(skb_needs_check(skb, tx_path))) {
  		int err;
  
  		/* We're going to init ->check field in TCP or UDP header */
  		err = skb_cow_head(skb, 0);
  		if (err < 0)
  			return ERR_PTR(err);
  	}
  
  	/* Only report GSO partial support if it will enable us to
  	 * support segmentation on this frame without needing additional
  	 * work.
  	 */
  	if (features & NETIF_F_GSO_PARTIAL) {
  		netdev_features_t partial_features = NETIF_F_GSO_ROBUST;
  		struct net_device *dev = skb->dev;
  
  		partial_features |= dev->features & dev->gso_partial_features;
  		if (!skb_gso_ok(skb, features | partial_features))
  			features &= ~NETIF_F_GSO_PARTIAL;
  	}
  
  	BUILD_BUG_ON(SKB_SGO_CB_OFFSET +
  		     sizeof(*SKB_GSO_CB(skb)) > sizeof(skb->cb));
  
  	SKB_GSO_CB(skb)->mac_offset = skb_headroom(skb);
  	SKB_GSO_CB(skb)->encap_level = 0;
  
  	skb_reset_mac_header(skb);
  	skb_reset_mac_len(skb);
  
  	segs = skb_mac_gso_segment(skb, features);
  
  	if (unlikely(skb_needs_check(skb, tx_path) && !IS_ERR(segs)))
  		skb_warn_bad_offload(skb);
  
  	return segs;
  }
  EXPORT_SYMBOL(__skb_gso_segment);
  
  /* Take action when hardware reception checksum errors are detected. */
  #ifdef CONFIG_BUG
  void netdev_rx_csum_fault(struct net_device *dev, struct sk_buff *skb)
  {
  	if (net_ratelimit()) {
  		pr_err("%s: hw csum failure\n", dev ? dev->name : "<unknown>");
  		skb_dump(KERN_ERR, skb, true);
  		dump_stack();
  	}
  }
  EXPORT_SYMBOL(netdev_rx_csum_fault);
  #endif
  
  /* XXX: check that highmem exists at all on the given machine. */
  static int illegal_highdma(struct net_device *dev, struct sk_buff *skb)
  {
  #ifdef CONFIG_HIGHMEM
  	int i;
  
  	if (!(dev->features & NETIF_F_HIGHDMA)) {
  		for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
  			skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
  
  			if (PageHighMem(skb_frag_page(frag)))
  				return 1;
  		}
  	}
  #endif
  	return 0;
  }
  
  /* If MPLS offload request, verify we are testing hardware MPLS features
   * instead of standard features for the netdev.
   */
  #if IS_ENABLED(CONFIG_NET_MPLS_GSO)
  static netdev_features_t net_mpls_features(struct sk_buff *skb,
  					   netdev_features_t features,
  					   __be16 type)
  {
  	if (eth_p_mpls(type))
  		features &= skb->dev->mpls_features;
  
  	return features;
  }
  #else
  static netdev_features_t net_mpls_features(struct sk_buff *skb,
  					   netdev_features_t features,
  					   __be16 type)
  {
  	return features;
  }
  #endif
  
  static netdev_features_t harmonize_features(struct sk_buff *skb,
  	netdev_features_t features)
  {
  	int tmp;
  	__be16 type;
  
  	type = skb_network_protocol(skb, &tmp);
  	features = net_mpls_features(skb, features, type);
  
  	if (skb->ip_summed != CHECKSUM_NONE &&
  	    !can_checksum_protocol(features, type)) {
  		features &= ~(NETIF_F_CSUM_MASK | NETIF_F_GSO_MASK);
  	}
  	if (illegal_highdma(skb->dev, skb))
  		features &= ~NETIF_F_SG;
  
  	return features;
  }
  
  netdev_features_t passthru_features_check(struct sk_buff *skb,
  					  struct net_device *dev,
  					  netdev_features_t features)
  {
  	return features;
  }
  EXPORT_SYMBOL(passthru_features_check);
  
  static netdev_features_t dflt_features_check(struct sk_buff *skb,
  					     struct net_device *dev,
  					     netdev_features_t features)
  {
  	return vlan_features_check(skb, features);
  }
  
  static netdev_features_t gso_features_check(const struct sk_buff *skb,
  					    struct net_device *dev,
  					    netdev_features_t features)
  {
  	u16 gso_segs = skb_shinfo(skb)->gso_segs;
  
  	if (gso_segs > dev->gso_max_segs)
  		return features & ~NETIF_F_GSO_MASK;
  
  	/* Support for GSO partial features requires software
  	 * intervention before we can actually process the packets
  	 * so we need to strip support for any partial features now
  	 * and we can pull them back in after we have partially
  	 * segmented the frame.
  	 */
  	if (!(skb_shinfo(skb)->gso_type & SKB_GSO_PARTIAL))
  		features &= ~dev->gso_partial_features;
  
  	/* Make sure to clear the IPv4 ID mangling feature if the
  	 * IPv4 header has the potential to be fragmented.
  	 */
  	if (skb_shinfo(skb)->gso_type & SKB_GSO_TCPV4) {
  		struct iphdr *iph = skb->encapsulation ?
  				    inner_ip_hdr(skb) : ip_hdr(skb);
  
  		if (!(iph->frag_off & htons(IP_DF)))
  			features &= ~NETIF_F_TSO_MANGLEID;
  	}
  
  	return features;
  }
  
  netdev_features_t netif_skb_features(struct sk_buff *skb)
  {
  	struct net_device *dev = skb->dev;
  	netdev_features_t features = dev->features;
  
  	if (skb_is_gso(skb))
  		features = gso_features_check(skb, dev, features);
  
  	/* If encapsulation offload request, verify we are testing
  	 * hardware encapsulation features instead of standard
  	 * features for the netdev
  	 */
  	if (skb->encapsulation)
  		features &= dev->hw_enc_features;
  
  	if (skb_vlan_tagged(skb))
  		features = netdev_intersect_features(features,
  						     dev->vlan_features |
  						     NETIF_F_HW_VLAN_CTAG_TX |
  						     NETIF_F_HW_VLAN_STAG_TX);
  
  	if (dev->netdev_ops->ndo_features_check)
  		features &= dev->netdev_ops->ndo_features_check(skb, dev,
  								features);
  	else
  		features &= dflt_features_check(skb, dev, features);
  
  	return harmonize_features(skb, features);
  }
  EXPORT_SYMBOL(netif_skb_features);
  
  static int xmit_one(struct sk_buff *skb, struct net_device *dev,
  		    struct netdev_queue *txq, bool more)
  {
  	unsigned int len;
  	int rc;
  
  	if (dev_nit_active(dev))
  		dev_queue_xmit_nit(skb, dev);
  
  	len = skb->len;
  	trace_net_dev_start_xmit(skb, dev);
  	rc = netdev_start_xmit(skb, dev, txq, more);
  	trace_net_dev_xmit(skb, rc, dev, len);
  
  	return rc;
  }
  
  struct sk_buff *dev_hard_start_xmit(struct sk_buff *first, struct net_device *dev,
  				    struct netdev_queue *txq, int *ret)
  {
  	struct sk_buff *skb = first;
  	int rc = NETDEV_TX_OK;
  
  	while (skb) {
  		struct sk_buff *next = skb->next;
  
  		skb_mark_not_on_list(skb);
  		rc = xmit_one(skb, dev, txq, next != NULL);
  		if (unlikely(!dev_xmit_complete(rc))) {
  			skb->next = next;
  			goto out;
  		}
  
  		skb = next;
  		if (netif_tx_queue_stopped(txq) && skb) {
  			rc = NETDEV_TX_BUSY;
  			break;
  		}
  	}
  
  out:
  	*ret = rc;
  	return skb;
  }
  
  static struct sk_buff *validate_xmit_vlan(struct sk_buff *skb,
  					  netdev_features_t features)
  {
  	if (skb_vlan_tag_present(skb) &&
  	    !vlan_hw_offload_capable(features, skb->vlan_proto))
  		skb = __vlan_hwaccel_push_inside(skb);
  	return skb;
  }
  
  int skb_csum_hwoffload_help(struct sk_buff *skb,
  			    const netdev_features_t features)
  {
  	if (unlikely(skb->csum_not_inet))
  		return !!(features & NETIF_F_SCTP_CRC) ? 0 :
  			skb_crc32c_csum_help(skb);
  
  	return !!(features & NETIF_F_CSUM_MASK) ? 0 : skb_checksum_help(skb);
  }
  EXPORT_SYMBOL(skb_csum_hwoffload_help);
  
  static struct sk_buff *validate_xmit_skb(struct sk_buff *skb, struct net_device *dev, bool *again)
  {
  	netdev_features_t features;
  
  	features = netif_skb_features(skb);
  	skb = validate_xmit_vlan(skb, features);
  	if (unlikely(!skb))
  		goto out_null;
  
  	skb = sk_validate_xmit_skb(skb, dev);
  	if (unlikely(!skb))
  		goto out_null;
  
  	if (netif_needs_gso(skb, features)) {
  		struct sk_buff *segs;
  
  		segs = skb_gso_segment(skb, features);
  		if (IS_ERR(segs)) {
  			goto out_kfree_skb;
  		} else if (segs) {
  			consume_skb(skb);
  			skb = segs;
  		}
  	} else {
  		if (skb_needs_linearize(skb, features) &&
  		    __skb_linearize(skb))
  			goto out_kfree_skb;
  
  		/* If packet is not checksummed and device does not
  		 * support checksumming for this protocol, complete
  		 * checksumming here.
  		 */
  		if (skb->ip_summed == CHECKSUM_PARTIAL) {
  			if (skb->encapsulation)
  				skb_set_inner_transport_header(skb,
  							       skb_checksum_start_offset(skb));
  			else
  				skb_set_transport_header(skb,
  							 skb_checksum_start_offset(skb));
  			if (skb_csum_hwoffload_help(skb, features))
  				goto out_kfree_skb;
  		}
  	}
  
  	skb = validate_xmit_xfrm(skb, features, again);
  
  	return skb;
  
  out_kfree_skb:
  	kfree_skb(skb);
  out_null:
  	atomic_long_inc(&dev->tx_dropped);
  	return NULL;
  }
  
  struct sk_buff *validate_xmit_skb_list(struct sk_buff *skb, struct net_device *dev, bool *again)
  {
  	struct sk_buff *next, *head = NULL, *tail;
  
  	for (; skb != NULL; skb = next) {
  		next = skb->next;
  		skb_mark_not_on_list(skb);
  
  		/* in case skb wont be segmented, point to itself */
  		skb->prev = skb;
  
  		skb = validate_xmit_skb(skb, dev, again);
  		if (!skb)
  			continue;
  
  		if (!head)
  			head = skb;
  		else
  			tail->next = skb;
  		/* If skb was segmented, skb->prev points to
  		 * the last segment. If not, it still contains skb.
  		 */
  		tail = skb->prev;
  	}
  	return head;
  }
  EXPORT_SYMBOL_GPL(validate_xmit_skb_list);
  
  static void qdisc_pkt_len_init(struct sk_buff *skb)
  {
  	const struct skb_shared_info *shinfo = skb_shinfo(skb);
  
  	qdisc_skb_cb(skb)->pkt_len = skb->len;
  
  	/* To get more precise estimation of bytes sent on wire,
  	 * we add to pkt_len the headers size of all segments
  	 */
  	if (shinfo->gso_size && skb_transport_header_was_set(skb)) {
  		unsigned int hdr_len;
  		u16 gso_segs = shinfo->gso_segs;
  
  		/* mac layer + network layer */
  		hdr_len = skb_transport_header(skb) - skb_mac_header(skb);
  
  		/* + transport layer */
  		if (likely(shinfo->gso_type & (SKB_GSO_TCPV4 | SKB_GSO_TCPV6))) {
  			const struct tcphdr *th;
  			struct tcphdr _tcphdr;
  
  			th = skb_header_pointer(skb, skb_transport_offset(skb),
  						sizeof(_tcphdr), &_tcphdr);
  			if (likely(th))
  				hdr_len += __tcp_hdrlen(th);
  		} else {
  			struct udphdr _udphdr;
  
  			if (skb_header_pointer(skb, skb_transport_offset(skb),
  					       sizeof(_udphdr), &_udphdr))
  				hdr_len += sizeof(struct udphdr);
  		}
  
  		if (shinfo->gso_type & SKB_GSO_DODGY)
  			gso_segs = DIV_ROUND_UP(skb->len - hdr_len,
  						shinfo->gso_size);
  
  		qdisc_skb_cb(skb)->pkt_len += (gso_segs - 1) * hdr_len;
  	}
  }
  
  static inline int __dev_xmit_skb(struct sk_buff *skb, struct Qdisc *q,
  				 struct net_device *dev,
  				 struct netdev_queue *txq)
  {
  	spinlock_t *root_lock = qdisc_lock(q);
  	struct sk_buff *to_free = NULL;
  	bool contended;
  	int rc;
  
  	qdisc_calculate_pkt_len(skb, q);
  
  	if (q->flags & TCQ_F_NOLOCK) {
  		rc = q->enqueue(skb, q, &to_free) & NET_XMIT_MASK;
  		qdisc_run(q);
  
  		if (unlikely(to_free))
  			kfree_skb_list(to_free);
  		return rc;
  	}
  
  	/*
  	 * Heuristic to force contended enqueues to serialize on a
  	 * separate lock before trying to get qdisc main lock.
  	 * This permits qdisc->running owner to get the lock more
  	 * often and dequeue packets faster.
  	 */
  	contended = qdisc_is_running(q);
  	if (unlikely(contended))
  		spin_lock(&q->busylock);
  
  	spin_lock(root_lock);
  	if (unlikely(test_bit(__QDISC_STATE_DEACTIVATED, &q->state))) {
  		__qdisc_drop(skb, &to_free);
  		rc = NET_XMIT_DROP;
  	} else if ((q->flags & TCQ_F_CAN_BYPASS) && !qdisc_qlen(q) &&
  		   qdisc_run_begin(q)) {
  		/*
  		 * This is a work-conserving queue; there are no old skbs
  		 * waiting to be sent out; and the qdisc is not running -
  		 * xmit the skb directly.
  		 */
  
  		qdisc_bstats_update(q, skb);
  
  		if (sch_direct_xmit(skb, q, dev, txq, root_lock, true)) {
  			if (unlikely(contended)) {
  				spin_unlock(&q->busylock);
  				contended = false;
  			}
  			__qdisc_run(q);
  		}
  
  		qdisc_run_end(q);
  		rc = NET_XMIT_SUCCESS;
  	} else {
  		rc = q->enqueue(skb, q, &to_free) & NET_XMIT_MASK;
  		if (qdisc_run_begin(q)) {
  			if (unlikely(contended)) {
  				spin_unlock(&q->busylock);
  				contended = false;
  			}
  			__qdisc_run(q);
  			qdisc_run_end(q);
  		}
  	}
  	spin_unlock(root_lock);
  	if (unlikely(to_free))
  		kfree_skb_list(to_free);
  	if (unlikely(contended))
  		spin_unlock(&q->busylock);
  	return rc;
  }
  
  #if IS_ENABLED(CONFIG_CGROUP_NET_PRIO)
  static void skb_update_prio(struct sk_buff *skb)
  {
  	const struct netprio_map *map;
  	const struct sock *sk;
  	unsigned int prioidx;
  
  	if (skb->priority)
  		return;
  	map = rcu_dereference_bh(skb->dev->priomap);
  	if (!map)
  		return;
  	sk = skb_to_full_sk(skb);
  	if (!sk)
  		return;
  
  	prioidx = sock_cgroup_prioidx(&sk->sk_cgrp_data);
  
  	if (prioidx < map->priomap_len)
  		skb->priority = map->priomap[prioidx];
  }
  #else
  #define skb_update_prio(skb)
  #endif
  
  /**
   *	dev_loopback_xmit - loop back @skb
   *	@net: network namespace this loopback is happening in
   *	@sk:  sk needed to be a netfilter okfn
   *	@skb: buffer to transmit
   */
  int dev_loopback_xmit(struct net *net, struct sock *sk, struct sk_buff *skb)
  {
  	skb_reset_mac_header(skb);
  	__skb_pull(skb, skb_network_offset(skb));
  	skb->pkt_type = PACKET_LOOPBACK;
  	skb->ip_summed = CHECKSUM_UNNECESSARY;
  	WARN_ON(!skb_dst(skb));
  	skb_dst_force(skb);
  	netif_rx_ni(skb);
  	return 0;
  }
  EXPORT_SYMBOL(dev_loopback_xmit);
  
  #ifdef CONFIG_NET_EGRESS
  static struct sk_buff *
  sch_handle_egress(struct sk_buff *skb, int *ret, struct net_device *dev)
  {
  	struct mini_Qdisc *miniq = rcu_dereference_bh(dev->miniq_egress);
  	struct tcf_result cl_res;
  
  	if (!miniq)
  		return skb;
  
  	/* qdisc_skb_cb(skb)->pkt_len was already set by the caller. */
  	mini_qdisc_bstats_cpu_update(miniq, skb);
  
  	switch (tcf_classify(skb, miniq->filter_list, &cl_res, false)) {
  	case TC_ACT_OK:
  	case TC_ACT_RECLASSIFY:
  		skb->tc_index = TC_H_MIN(cl_res.classid);
  		break;
  	case TC_ACT_SHOT:
  		mini_qdisc_qstats_cpu_drop(miniq);
  		*ret = NET_XMIT_DROP;
  		kfree_skb(skb);
  		return NULL;
  	case TC_ACT_STOLEN:
  	case TC_ACT_QUEUED:
  	case TC_ACT_TRAP:
  		*ret = NET_XMIT_SUCCESS;
  		consume_skb(skb);
  		return NULL;
  	case TC_ACT_REDIRECT:
  		/* No need to push/pop skb's mac_header here on egress! */
  		skb_do_redirect(skb);
  		*ret = NET_XMIT_SUCCESS;
  		return NULL;
  	default:
  		break;
  	}
  
  	return skb;
  }
  #endif /* CONFIG_NET_EGRESS */
  
  #ifdef CONFIG_XPS
  static int __get_xps_queue_idx(struct net_device *dev, struct sk_buff *skb,
  			       struct xps_dev_maps *dev_maps, unsigned int tci)
  {
  	struct xps_map *map;
  	int queue_index = -1;
  
  	if (dev->num_tc) {
  		tci *= dev->num_tc;
  		tci += netdev_get_prio_tc_map(dev, skb->priority);
  	}
  
  	map = rcu_dereference(dev_maps->attr_map[tci]);
  	if (map) {
  		if (map->len == 1)
  			queue_index = map->queues[0];
  		else
  			queue_index = map->queues[reciprocal_scale(
  						skb_get_hash(skb), map->len)];
  		if (unlikely(queue_index >= dev->real_num_tx_queues))
  			queue_index = -1;
  	}
  	return queue_index;
  }
  #endif
  
  static int get_xps_queue(struct net_device *dev, struct net_device *sb_dev,
  			 struct sk_buff *skb)
  {
  #ifdef CONFIG_XPS
  	struct xps_dev_maps *dev_maps;
  	struct sock *sk = skb->sk;
  	int queue_index = -1;
  
  	if (!static_key_false(&xps_needed))
  		return -1;
  
  	rcu_read_lock();
  	if (!static_key_false(&xps_rxqs_needed))
  		goto get_cpus_map;
  
  	dev_maps = rcu_dereference(sb_dev->xps_rxqs_map);
  	if (dev_maps) {
  		int tci = sk_rx_queue_get(sk);
  
  		if (tci >= 0 && tci < dev->num_rx_queues)
  			queue_index = __get_xps_queue_idx(dev, skb, dev_maps,
  							  tci);
  	}
  
  get_cpus_map:
  	if (queue_index < 0) {
  		dev_maps = rcu_dereference(sb_dev->xps_cpus_map);
  		if (dev_maps) {
  			unsigned int tci = skb->sender_cpu - 1;
  
  			queue_index = __get_xps_queue_idx(dev, skb, dev_maps,
  							  tci);
  		}
  	}
  	rcu_read_unlock();
  
  	return queue_index;
  #else
  	return -1;
  #endif
  }
  
  u16 dev_pick_tx_zero(struct net_device *dev, struct sk_buff *skb,
  		     struct net_device *sb_dev)
  {
  	return 0;
  }
  EXPORT_SYMBOL(dev_pick_tx_zero);
  
  u16 dev_pick_tx_cpu_id(struct net_device *dev, struct sk_buff *skb,
  		       struct net_device *sb_dev)
  {
  	return (u16)raw_smp_processor_id() % dev->real_num_tx_queues;
  }
  EXPORT_SYMBOL(dev_pick_tx_cpu_id);
  
  u16 netdev_pick_tx(struct net_device *dev, struct sk_buff *skb,
  		     struct net_device *sb_dev)
  {
  	struct sock *sk = skb->sk;
  	int queue_index = sk_tx_queue_get(sk);
  
  	sb_dev = sb_dev ? : dev;
  
  	if (queue_index < 0 || skb->ooo_okay ||
  	    queue_index >= dev->real_num_tx_queues) {
  		int new_index = get_xps_queue(dev, sb_dev, skb);
  
  		if (new_index < 0)
  			new_index = skb_tx_hash(dev, sb_dev, skb);
  
  		if (queue_index != new_index && sk &&
  		    sk_fullsock(sk) &&
  		    rcu_access_pointer(sk->sk_dst_cache))
  			sk_tx_queue_set(sk, new_index);
  
  		queue_index = new_index;
  	}
  
  	return queue_index;
  }
  EXPORT_SYMBOL(netdev_pick_tx);
  
  struct netdev_queue *netdev_core_pick_tx(struct net_device *dev,
  					 struct sk_buff *skb,
  					 struct net_device *sb_dev)
  {
  	int queue_index = 0;
  
  #ifdef CONFIG_XPS
  	u32 sender_cpu = skb->sender_cpu - 1;
  
  	if (sender_cpu >= (u32)NR_CPUS)
  		skb->sender_cpu = raw_smp_processor_id() + 1;
  #endif
  
  	if (dev->real_num_tx_queues != 1) {
  		const struct net_device_ops *ops = dev->netdev_ops;
  
  		if (ops->ndo_select_queue)
  			queue_index = ops->ndo_select_queue(dev, skb, sb_dev);
  		else
  			queue_index = netdev_pick_tx(dev, skb, sb_dev);
  
  		queue_index = netdev_cap_txqueue(dev, queue_index);
  	}
  
  	skb_set_queue_mapping(skb, queue_index);
  	return netdev_get_tx_queue(dev, queue_index);
  }
  
  /**
   *	__dev_queue_xmit - transmit a buffer
   *	@skb: buffer to transmit
   *	@sb_dev: suboordinate device used for L2 forwarding offload
   *
   *	Queue a buffer for transmission to a network device. The caller must
   *	have set the device and priority and built the buffer before calling
   *	this function. The function can be called from an interrupt.
   *
   *	A negative errno code is returned on a failure. A success does not
   *	guarantee the frame will be transmitted as it may be dropped due
   *	to congestion or traffic shaping.
   *
   * -----------------------------------------------------------------------------------
   *      I notice this method can also return errors from the queue disciplines,
   *      including NET_XMIT_DROP, which is a positive value.  So, errors can also
   *      be positive.
   *
   *      Regardless of the return value, the skb is consumed, so it is currently
   *      difficult to retry a send to this method.  (You can bump the ref count
   *      before sending to hold a reference for retry if you are careful.)
   *
   *      When calling this method, interrupts MUST be enabled.  This is because
   *      the BH enable code must have IRQs enabled so that it will not deadlock.
   *          --BLG
   */
  static int __dev_queue_xmit(struct sk_buff *skb, struct net_device *sb_dev)
  {
  	struct net_device *dev = skb->dev;
  	struct netdev_queue *txq;
  	struct Qdisc *q;
  	int rc = -ENOMEM;
  	bool again = false;
  
  	skb_reset_mac_header(skb);
  
  	if (unlikely(skb_shinfo(skb)->tx_flags & SKBTX_SCHED_TSTAMP))
  		__skb_tstamp_tx(skb, NULL, skb->sk, SCM_TSTAMP_SCHED);
  
  	/* Disable soft irqs for various locks below. Also
  	 * stops preemption for RCU.
  	 */
  	rcu_read_lock_bh();
  
  	skb_update_prio(skb);
  
  	qdisc_pkt_len_init(skb);
  #ifdef CONFIG_NET_CLS_ACT
  	skb->tc_at_ingress = 0;
  # ifdef CONFIG_NET_EGRESS
  	if (static_branch_unlikely(&egress_needed_key)) {
  		skb = sch_handle_egress(skb, &rc, dev);
  		if (!skb)
  			goto out;
  	}
  # endif
  #endif
  	/* If device/qdisc don't need skb->dst, release it right now while
  	 * its hot in this cpu cache.
  	 */
  	if (dev->priv_flags & IFF_XMIT_DST_RELEASE)
  		skb_dst_drop(skb);
  	else
  		skb_dst_force(skb);
  
  	txq = netdev_core_pick_tx(dev, skb, sb_dev);
  	q = rcu_dereference_bh(txq->qdisc);
  
  	trace_net_dev_queue(skb);
  	if (q->enqueue) {
  		rc = __dev_xmit_skb(skb, q, dev, txq);
  		goto out;
  	}
  
  	/* The device has no queue. Common case for software devices:
  	 * loopback, all the sorts of tunnels...
  
  	 * Really, it is unlikely that netif_tx_lock protection is necessary
  	 * here.  (f.e. loopback and IP tunnels are clean ignoring statistics
  	 * counters.)
  	 * However, it is possible, that they rely on protection
  	 * made by us here.
  
  	 * Check this and shot the lock. It is not prone from deadlocks.
  	 *Either shot noqueue qdisc, it is even simpler 8)
  	 */
  	if (dev->flags & IFF_UP) {
  		int cpu = smp_processor_id(); /* ok because BHs are off */
  
  		if (txq->xmit_lock_owner != cpu) {
  			if (dev_xmit_recursion())
  				goto recursion_alert;
  
  			skb = validate_xmit_skb(skb, dev, &again);
  			if (!skb)
  				goto out;
  
  			HARD_TX_LOCK(dev, txq, cpu);
  
  			if (!netif_xmit_stopped(txq)) {
  				dev_xmit_recursion_inc();
  				skb = dev_hard_start_xmit(skb, dev, txq, &rc);
  				dev_xmit_recursion_dec();
  				if (dev_xmit_complete(rc)) {
  					HARD_TX_UNLOCK(dev, txq);
  					goto out;
  				}
  			}
  			HARD_TX_UNLOCK(dev, txq);
  			net_crit_ratelimited("Virtual device %s asks to queue packet!\n",
  					     dev->name);
  		} else {
  			/* Recursion is detected! It is possible,
  			 * unfortunately
  			 */
  recursion_alert:
  			net_crit_ratelimited("Dead loop on virtual device %s, fix it urgently!\n",
  					     dev->name);
  		}
  	}
  
  	rc = -ENETDOWN;
  	rcu_read_unlock_bh();
  
  	atomic_long_inc(&dev->tx_dropped);
  	kfree_skb_list(skb);
  	return rc;
  out:
  	rcu_read_unlock_bh();
  	return rc;
  }
  
  int dev_queue_xmit(struct sk_buff *skb)
  {
  	return __dev_queue_xmit(skb, NULL);
  }
  EXPORT_SYMBOL(dev_queue_xmit);
  
  int dev_queue_xmit_accel(struct sk_buff *skb, struct net_device *sb_dev)
  {
  	return __dev_queue_xmit(skb, sb_dev);
  }
  EXPORT_SYMBOL(dev_queue_xmit_accel);
  
  int dev_direct_xmit(struct sk_buff *skb, u16 queue_id)
  {
  	struct net_device *dev = skb->dev;
  	struct sk_buff *orig_skb = skb;
  	struct netdev_queue *txq;
  	int ret = NETDEV_TX_BUSY;
  	bool again = false;
  
  	if (unlikely(!netif_running(dev) ||
  		     !netif_carrier_ok(dev)))
  		goto drop;
  
  	skb = validate_xmit_skb_list(skb, dev, &again);
  	if (skb != orig_skb)
  		goto drop;
  
  	skb_set_queue_mapping(skb, queue_id);
  	txq = skb_get_tx_queue(dev, skb);
  
  	local_bh_disable();
  
  	dev_xmit_recursion_inc();
  	HARD_TX_LOCK(dev, txq, smp_processor_id());
  	if (!netif_xmit_frozen_or_drv_stopped(txq))
  		ret = netdev_start_xmit(skb, dev, txq, false);
  	HARD_TX_UNLOCK(dev, txq);
  	dev_xmit_recursion_dec();
  
  	local_bh_enable();
  
  	if (!dev_xmit_complete(ret))
  		kfree_skb(skb);
  
  	return ret;
  drop:
  	atomic_long_inc(&dev->tx_dropped);
  	kfree_skb_list(skb);
  	return NET_XMIT_DROP;
  }
  EXPORT_SYMBOL(dev_direct_xmit);
  
  /*************************************************************************
   *			Receiver routines
   *************************************************************************/
  
  int netdev_max_backlog __read_mostly = 1000;
  EXPORT_SYMBOL(netdev_max_backlog);
  
  int netdev_tstamp_prequeue __read_mostly = 1;
  int netdev_budget __read_mostly = 300;
  /* Must be at least 2 jiffes to guarantee 1 jiffy timeout */
  unsigned int __read_mostly netdev_budget_usecs = 2 * USEC_PER_SEC / HZ;
  int weight_p __read_mostly = 64;           /* old backlog weight */
  int dev_weight_rx_bias __read_mostly = 1;  /* bias for backlog weight */
  int dev_weight_tx_bias __read_mostly = 1;  /* bias for output_queue quota */
  int dev_rx_weight __read_mostly = 64;
  int dev_tx_weight __read_mostly = 64;
  /* Maximum number of GRO_NORMAL skbs to batch up for list-RX */
  int gro_normal_batch __read_mostly = 8;
  
  /* Called with irq disabled */
  static inline void ____napi_schedule(struct softnet_data *sd,
  				     struct napi_struct *napi)
  {
  	list_add_tail(&napi->poll_list, &sd->poll_list);
  	__raise_softirq_irqoff(NET_RX_SOFTIRQ);
  }
  
  #ifdef CONFIG_RPS
  
  /* One global table that all flow-based protocols share. */
  struct rps_sock_flow_table __rcu *rps_sock_flow_table __read_mostly;
  EXPORT_SYMBOL(rps_sock_flow_table);
  u32 rps_cpu_mask __read_mostly;
  EXPORT_SYMBOL(rps_cpu_mask);
  
  struct static_key_false rps_needed __read_mostly;
  EXPORT_SYMBOL(rps_needed);
  struct static_key_false rfs_needed __read_mostly;
  EXPORT_SYMBOL(rfs_needed);
  
  static struct rps_dev_flow *
  set_rps_cpu(struct net_device *dev, struct sk_buff *skb,
  	    struct rps_dev_flow *rflow, u16 next_cpu)
  {
  	if (next_cpu < nr_cpu_ids) {
  #ifdef CONFIG_RFS_ACCEL
  		struct netdev_rx_queue *rxqueue;
  		struct rps_dev_flow_table *flow_table;
  		struct rps_dev_flow *old_rflow;
  		u32 flow_id;
  		u16 rxq_index;
  		int rc;
  
  		/* Should we steer this flow to a different hardware queue? */
  		if (!skb_rx_queue_recorded(skb) || !dev->rx_cpu_rmap ||
  		    !(dev->features & NETIF_F_NTUPLE))
  			goto out;
  		rxq_index = cpu_rmap_lookup_index(dev->rx_cpu_rmap, next_cpu);
  		if (rxq_index == skb_get_rx_queue(skb))
  			goto out;
  
  		rxqueue = dev->_rx + rxq_index;
  		flow_table = rcu_dereference(rxqueue->rps_flow_table);
  		if (!flow_table)
  			goto out;
  		flow_id = skb_get_hash(skb) & flow_table->mask;
  		rc = dev->netdev_ops->ndo_rx_flow_steer(dev, skb,
  							rxq_index, flow_id);
  		if (rc < 0)
  			goto out;
  		old_rflow = rflow;
  		rflow = &flow_table->flows[flow_id];
  		rflow->filter = rc;
  		if (old_rflow->filter == rflow->filter)
  			old_rflow->filter = RPS_NO_FILTER;
  	out:
  #endif
  		rflow->last_qtail =
  			per_cpu(softnet_data, next_cpu).input_queue_head;
  	}
  
  	rflow->cpu = next_cpu;
  	return rflow;
  }
  
  /*
   * get_rps_cpu is called from netif_receive_skb and returns the target
   * CPU from the RPS map of the receiving queue for a given skb.
   * rcu_read_lock must be held on entry.
   */
  static int get_rps_cpu(struct net_device *dev, struct sk_buff *skb,
  		       struct rps_dev_flow **rflowp)
  {
  	const struct rps_sock_flow_table *sock_flow_table;
  	struct netdev_rx_queue *rxqueue = dev->_rx;
  	struct rps_dev_flow_table *flow_table;
  	struct rps_map *map;
  	int cpu = -1;
  	u32 tcpu;
  	u32 hash;
  
  	if (skb_rx_queue_recorded(skb)) {
  		u16 index = skb_get_rx_queue(skb);
  
  		if (unlikely(index >= dev->real_num_rx_queues)) {
  			WARN_ONCE(dev->real_num_rx_queues > 1,
  				  "%s received packet on queue %u, but number "
  				  "of RX queues is %u\n",
  				  dev->name, index, dev->real_num_rx_queues);
  			goto done;
  		}
  		rxqueue += index;
  	}
  
  	/* Avoid computing hash if RFS/RPS is not active for this rxqueue */
  
  	flow_table = rcu_dereference(rxqueue->rps_flow_table);
  	map = rcu_dereference(rxqueue->rps_map);
  	if (!flow_table && !map)
  		goto done;
  
  	skb_reset_network_header(skb);
  	hash = skb_get_hash(skb);
  	if (!hash)
  		goto done;
  
  	sock_flow_table = rcu_dereference(rps_sock_flow_table);
  	if (flow_table && sock_flow_table) {
  		struct rps_dev_flow *rflow;
  		u32 next_cpu;
  		u32 ident;
  
  		/* First check into global flow table if there is a match */
  		ident = sock_flow_table->ents[hash & sock_flow_table->mask];
  		if ((ident ^ hash) & ~rps_cpu_mask)
  			goto try_rps;
  
  		next_cpu = ident & rps_cpu_mask;
  
  		/* OK, now we know there is a match,
  		 * we can look at the local (per receive queue) flow table
  		 */
  		rflow = &flow_table->flows[hash & flow_table->mask];
  		tcpu = rflow->cpu;
  
  		/*
  		 * If the desired CPU (where last recvmsg was done) is
  		 * different from current CPU (one in the rx-queue flow
  		 * table entry), switch if one of the following holds:
  		 *   - Current CPU is unset (>= nr_cpu_ids).
  		 *   - Current CPU is offline.
  		 *   - The current CPU's queue tail has advanced beyond the
  		 *     last packet that was enqueued using this table entry.
  		 *     This guarantees that all previous packets for the flow
  		 *     have been dequeued, thus preserving in order delivery.
  		 */
  		if (unlikely(tcpu != next_cpu) &&
  		    (tcpu >= nr_cpu_ids || !cpu_online(tcpu) ||
  		     ((int)(per_cpu(softnet_data, tcpu).input_queue_head -
  		      rflow->last_qtail)) >= 0)) {
  			tcpu = next_cpu;
  			rflow = set_rps_cpu(dev, skb, rflow, next_cpu);
  		}
  
  		if (tcpu < nr_cpu_ids && cpu_online(tcpu)) {
  			*rflowp = rflow;
  			cpu = tcpu;
  			goto done;
  		}
  	}
  
  try_rps:
  
  	if (map) {
  		tcpu = map->cpus[reciprocal_scale(hash, map->len)];
  		if (cpu_online(tcpu)) {
  			cpu = tcpu;
  			goto done;
  		}
  	}
  
  done:
  	return cpu;
  }
  
  #ifdef CONFIG_RFS_ACCEL
  
  /**
   * rps_may_expire_flow - check whether an RFS hardware filter may be removed
   * @dev: Device on which the filter was set
   * @rxq_index: RX queue index
   * @flow_id: Flow ID passed to ndo_rx_flow_steer()
   * @filter_id: Filter ID returned by ndo_rx_flow_steer()
   *
   * Drivers that implement ndo_rx_flow_steer() should periodically call
   * this function for each installed filter and remove the filters for
   * which it returns %true.
   */
  bool rps_may_expire_flow(struct net_device *dev, u16 rxq_index,
  			 u32 flow_id, u16 filter_id)
  {
  	struct netdev_rx_queue *rxqueue = dev->_rx + rxq_index;
  	struct rps_dev_flow_table *flow_table;
  	struct rps_dev_flow *rflow;
  	bool expire = true;
  	unsigned int cpu;
  
  	rcu_read_lock();
  	flow_table = rcu_dereference(rxqueue->rps_flow_table);
  	if (flow_table && flow_id <= flow_table->mask) {
  		rflow = &flow_table->flows[flow_id];
  		cpu = READ_ONCE(rflow->cpu);
  		if (rflow->filter == filter_id && cpu < nr_cpu_ids &&
  		    ((int)(per_cpu(softnet_data, cpu).input_queue_head -
  			   rflow->last_qtail) <
  		     (int)(10 * flow_table->mask)))
  			expire = false;
  	}
  	rcu_read_unlock();
  	return expire;
  }
  EXPORT_SYMBOL(rps_may_expire_flow);
  
  #endif /* CONFIG_RFS_ACCEL */
  
  /* Called from hardirq (IPI) context */
  static void rps_trigger_softirq(void *data)
  {
  	struct softnet_data *sd = data;
  
  	____napi_schedule(sd, &sd->backlog);
  	sd->received_rps++;
  }
  
  #endif /* CONFIG_RPS */
  
  /*
   * Check if this softnet_data structure is another cpu one
   * If yes, queue it to our IPI list and return 1
   * If no, return 0
   */
  static int rps_ipi_queued(struct softnet_data *sd)
  {
  #ifdef CONFIG_RPS
  	struct softnet_data *mysd = this_cpu_ptr(&softnet_data);
  
  	if (sd != mysd) {
  		sd->rps_ipi_next = mysd->rps_ipi_list;
  		mysd->rps_ipi_list = sd;
  
  		__raise_softirq_irqoff(NET_RX_SOFTIRQ);
  		return 1;
  	}
  #endif /* CONFIG_RPS */
  	return 0;
  }
  
  #ifdef CONFIG_NET_FLOW_LIMIT
  int netdev_flow_limit_table_len __read_mostly = (1 << 12);
  #endif
  
  static bool skb_flow_limit(struct sk_buff *skb, unsigned int qlen)
  {
  #ifdef CONFIG_NET_FLOW_LIMIT
  	struct sd_flow_limit *fl;
  	struct softnet_data *sd;
  	unsigned int old_flow, new_flow;
  
  	if (qlen < (netdev_max_backlog >> 1))
  		return false;
  
  	sd = this_cpu_ptr(&softnet_data);
  
  	rcu_read_lock();
  	fl = rcu_dereference(sd->flow_limit);
  	if (fl) {
  		new_flow = skb_get_hash(skb) & (fl->num_buckets - 1);
  		old_flow = fl->history[fl->history_head];
  		fl->history[fl->history_head] = new_flow;
  
  		fl->history_head++;
  		fl->history_head &= FLOW_LIMIT_HISTORY - 1;
  
  		if (likely(fl->buckets[old_flow]))
  			fl->buckets[old_flow]--;
  
  		if (++fl->buckets[new_flow] > (FLOW_LIMIT_HISTORY >> 1)) {
  			fl->count++;
  			rcu_read_unlock();
  			return true;
  		}
  	}
  	rcu_read_unlock();
  #endif
  	return false;
  }
  
  /*
   * enqueue_to_backlog is called to queue an skb to a per CPU backlog
   * queue (may be a remote CPU queue).
   */
  static int enqueue_to_backlog(struct sk_buff *skb, int cpu,
  			      unsigned int *qtail)
  {
  	struct softnet_data *sd;
  	unsigned long flags;
  	unsigned int qlen;
  
  	sd = &per_cpu(softnet_data, cpu);
  
  	local_irq_save(flags);
  
  	rps_lock(sd);
  	if (!netif_running(skb->dev))
  		goto drop;
  	qlen = skb_queue_len(&sd->input_pkt_queue);
  	if (qlen <= netdev_max_backlog && !skb_flow_limit(skb, qlen)) {
  		if (qlen) {
  enqueue:
  			__skb_queue_tail(&sd->input_pkt_queue, skb);
  			input_queue_tail_incr_save(sd, qtail);
  			rps_unlock(sd);
  			local_irq_restore(flags);
  			return NET_RX_SUCCESS;
  		}
  
  		/* Schedule NAPI for backlog device
  		 * We can use non atomic operation since we own the queue lock
  		 */
  		if (!__test_and_set_bit(NAPI_STATE_SCHED, &sd->backlog.state)) {
  			if (!rps_ipi_queued(sd))
  				____napi_schedule(sd, &sd->backlog);
  		}
  		goto enqueue;
  	}
  
  drop:
  	sd->dropped++;
  	rps_unlock(sd);
  
  	local_irq_restore(flags);
  
  	atomic_long_inc(&skb->dev->rx_dropped);
  	kfree_skb(skb);
  	return NET_RX_DROP;
  }
  
  static struct netdev_rx_queue *netif_get_rxqueue(struct sk_buff *skb)
  {
  	struct net_device *dev = skb->dev;
  	struct netdev_rx_queue *rxqueue;
  
  	rxqueue = dev->_rx;
  
  	if (skb_rx_queue_recorded(skb)) {
  		u16 index = skb_get_rx_queue(skb);
  
  		if (unlikely(index >= dev->real_num_rx_queues)) {
  			WARN_ONCE(dev->real_num_rx_queues > 1,
  				  "%s received packet on queue %u, but number "
  				  "of RX queues is %u\n",
  				  dev->name, index, dev->real_num_rx_queues);
  
  			return rxqueue; /* Return first rxqueue */
  		}
  		rxqueue += index;
  	}
  	return rxqueue;
  }
  
  static u32 netif_receive_generic_xdp(struct sk_buff *skb,
  				     struct xdp_buff *xdp,
  				     struct bpf_prog *xdp_prog)
  {
  	struct netdev_rx_queue *rxqueue;
  	void *orig_data, *orig_data_end;
  	u32 metalen, act = XDP_DROP;
  	__be16 orig_eth_type;
  	struct ethhdr *eth;
  	bool orig_bcast;
  	int hlen, off;
  	u32 mac_len;
  
  	/* Reinjected packets coming from act_mirred or similar should
  	 * not get XDP generic processing.
  	 */
  	if (skb_is_redirected(skb))
  		return XDP_PASS;
  
  	/* XDP packets must be linear and must have sufficient headroom
  	 * of XDP_PACKET_HEADROOM bytes. This is the guarantee that also
  	 * native XDP provides, thus we need to do it here as well.
  	 */
  	if (skb_cloned(skb) || skb_is_nonlinear(skb) ||
  	    skb_headroom(skb) < XDP_PACKET_HEADROOM) {
  		int hroom = XDP_PACKET_HEADROOM - skb_headroom(skb);
  		int troom = skb->tail + skb->data_len - skb->end;
  
  		/* In case we have to go down the path and also linearize,
  		 * then lets do the pskb_expand_head() work just once here.
  		 */
  		if (pskb_expand_head(skb,
  				     hroom > 0 ? ALIGN(hroom, NET_SKB_PAD) : 0,
  				     troom > 0 ? troom + 128 : 0, GFP_ATOMIC))
  			goto do_drop;
  		if (skb_linearize(skb))
  			goto do_drop;
  	}
  
  	/* The XDP program wants to see the packet starting at the MAC
  	 * header.
  	 */
  	mac_len = skb->data - skb_mac_header(skb);
  	hlen = skb_headlen(skb) + mac_len;
  	xdp->data = skb->data - mac_len;
  	xdp->data_meta = xdp->data;
  	xdp->data_end = xdp->data + hlen;
  	xdp->data_hard_start = skb->data - skb_headroom(skb);
  	orig_data_end = xdp->data_end;
  	orig_data = xdp->data;
  	eth = (struct ethhdr *)xdp->data;
  	orig_bcast = is_multicast_ether_addr_64bits(eth->h_dest);
  	orig_eth_type = eth->h_proto;
  
  	rxqueue = netif_get_rxqueue(skb);
  	xdp->rxq = &rxqueue->xdp_rxq;
  
  	act = bpf_prog_run_xdp(xdp_prog, xdp);
  
  	/* check if bpf_xdp_adjust_head was used */
  	off = xdp->data - orig_data;
  	if (off) {
  		if (off > 0)
  			__skb_pull(skb, off);
  		else if (off < 0)
  			__skb_push(skb, -off);
  
  		skb->mac_header += off;
  		skb_reset_network_header(skb);
  	}
  
  	/* check if bpf_xdp_adjust_tail was used. it can only "shrink"
  	 * pckt.
  	 */
  	off = orig_data_end - xdp->data_end;
  	if (off != 0) {
  		skb_set_tail_pointer(skb, xdp->data_end - xdp->data);
  		skb->len -= off;
  
  	}
  
  	/* check if XDP changed eth hdr such SKB needs update */
  	eth = (struct ethhdr *)xdp->data;
  	if ((orig_eth_type != eth->h_proto) ||
  	    (orig_bcast != is_multicast_ether_addr_64bits(eth->h_dest))) {
  		__skb_push(skb, ETH_HLEN);
  		skb->protocol = eth_type_trans(skb, skb->dev);
  	}
  
  	switch (act) {
  	case XDP_REDIRECT:
  	case XDP_TX:
  		__skb_push(skb, mac_len);
  		break;
  	case XDP_PASS:
  		metalen = xdp->data - xdp->data_meta;
  		if (metalen)
  			skb_metadata_set(skb, metalen);
  		break;
  	default:
  		bpf_warn_invalid_xdp_action(act);
  		/* fall through */
  	case XDP_ABORTED:
  		trace_xdp_exception(skb->dev, xdp_prog, act);
  		/* fall through */
  	case XDP_DROP:
  	do_drop:
  		kfree_skb(skb);
  		break;
  	}
  
  	return act;
  }
  
  /* When doing generic XDP we have to bypass the qdisc layer and the
   * network taps in order to match in-driver-XDP behavior.
   */
  void generic_xdp_tx(struct sk_buff *skb, struct bpf_prog *xdp_prog)
  {
  	struct net_device *dev = skb->dev;
  	struct netdev_queue *txq;
  	bool free_skb = true;
  	int cpu, rc;
  
  	txq = netdev_core_pick_tx(dev, skb, NULL);
  	cpu = smp_processor_id();
  	HARD_TX_LOCK(dev, txq, cpu);
  	if (!netif_xmit_stopped(txq)) {
  		rc = netdev_start_xmit(skb, dev, txq, 0);
  		if (dev_xmit_complete(rc))
  			free_skb = false;
  	}
  	HARD_TX_UNLOCK(dev, txq);
  	if (free_skb) {
  		trace_xdp_exception(dev, xdp_prog, XDP_TX);
  		kfree_skb(skb);
  	}
  }
  EXPORT_SYMBOL_GPL(generic_xdp_tx);
  
  static DEFINE_STATIC_KEY_FALSE(generic_xdp_needed_key);
  
  int do_xdp_generic(struct bpf_prog *xdp_prog, struct sk_buff *skb)
  {
  	if (xdp_prog) {
  		struct xdp_buff xdp;
  		u32 act;
  		int err;
  
  		act = netif_receive_generic_xdp(skb, &xdp, xdp_prog);
  		if (act != XDP_PASS) {
  			switch (act) {
  			case XDP_REDIRECT:
  				err = xdp_do_generic_redirect(skb->dev, skb,
  							      &xdp, xdp_prog);
  				if (err)
  					goto out_redir;
  				break;
  			case XDP_TX:
  				generic_xdp_tx(skb, xdp_prog);
  				break;
  			}
  			return XDP_DROP;
  		}
  	}
  	return XDP_PASS;
  out_redir:
  	kfree_skb(skb);
  	return XDP_DROP;
  }
  EXPORT_SYMBOL_GPL(do_xdp_generic);
  
  static int netif_rx_internal(struct sk_buff *skb)
  {
  	int ret;
  
  	net_timestamp_check(netdev_tstamp_prequeue, skb);
  
  	trace_netif_rx(skb);
  
  #ifdef CONFIG_RPS
  	if (static_branch_unlikely(&rps_needed)) {
  		struct rps_dev_flow voidflow, *rflow = &voidflow;
  		int cpu;
  
  		preempt_disable();
  		rcu_read_lock();
  
  		cpu = get_rps_cpu(skb->dev, skb, &rflow);
  		if (cpu < 0)
  			cpu = smp_processor_id();
  
  		ret = enqueue_to_backlog(skb, cpu, &rflow->last_qtail);
  
  		rcu_read_unlock();
  		preempt_enable();
  	} else
  #endif
  	{
  		unsigned int qtail;
  
  		ret = enqueue_to_backlog(skb, get_cpu(), &qtail);
  		put_cpu();
  	}
  	return ret;
  }
  
  /**
   *	netif_rx	-	post buffer to the network code
   *	@skb: buffer to post
   *
   *	This function receives a packet from a device driver and queues it for
   *	the upper (protocol) levels to process.  It always succeeds. The buffer
   *	may be dropped during processing for congestion control or by the
   *	protocol layers.
   *
   *	return values:
   *	NET_RX_SUCCESS	(no congestion)
   *	NET_RX_DROP     (packet was dropped)
   *
   */
  
  int netif_rx(struct sk_buff *skb)
  {
  	int ret;
  
  	trace_netif_rx_entry(skb);
  
  	ret = netif_rx_internal(skb);
  	trace_netif_rx_exit(ret);
  
  	return ret;
  }
  EXPORT_SYMBOL(netif_rx);
  
  int netif_rx_ni(struct sk_buff *skb)
  {
  	int err;
  
  	trace_netif_rx_ni_entry(skb);
  
  	preempt_disable();
  	err = netif_rx_internal(skb);
  	if (local_softirq_pending())
  		do_softirq();
  	preempt_enable();
  	trace_netif_rx_ni_exit(err);
  
  	return err;
  }
  EXPORT_SYMBOL(netif_rx_ni);
  
  static __latent_entropy void net_tx_action(struct softirq_action *h)
  {
  	struct softnet_data *sd = this_cpu_ptr(&softnet_data);
  
  	if (sd->completion_queue) {
  		struct sk_buff *clist;
  
  		local_irq_disable();
  		clist = sd->completion_queue;
  		sd->completion_queue = NULL;
  		local_irq_enable();
  
  		while (clist) {
  			struct sk_buff *skb = clist;
  
  			clist = clist->next;
  
  			WARN_ON(refcount_read(&skb->users));
  			if (likely(get_kfree_skb_cb(skb)->reason == SKB_REASON_CONSUMED))
  				trace_consume_skb(skb);
  			else
  				trace_kfree_skb(skb, net_tx_action);
  
  			if (skb->fclone != SKB_FCLONE_UNAVAILABLE)
  				__kfree_skb(skb);
  			else
  				__kfree_skb_defer(skb);
  		}
  
  		__kfree_skb_flush();
  	}
  
  	if (sd->output_queue) {
  		struct Qdisc *head;
  
  		local_irq_disable();
  		head = sd->output_queue;
  		sd->output_queue = NULL;
  		sd->output_queue_tailp = &sd->output_queue;
  		local_irq_enable();
  
  		while (head) {
  			struct Qdisc *q = head;
  			spinlock_t *root_lock = NULL;
  
  			head = head->next_sched;
  
  			if (!(q->flags & TCQ_F_NOLOCK)) {
  				root_lock = qdisc_lock(q);
  				spin_lock(root_lock);
  			}
  			/* We need to make sure head->next_sched is read
  			 * before clearing __QDISC_STATE_SCHED
  			 */
  			smp_mb__before_atomic();
  			clear_bit(__QDISC_STATE_SCHED, &q->state);
  			qdisc_run(q);
  			if (root_lock)
  				spin_unlock(root_lock);
  		}
  	}
  
  	xfrm_dev_backlog(sd);
  }
  
  #if IS_ENABLED(CONFIG_BRIDGE) && IS_ENABLED(CONFIG_ATM_LANE)
  /* This hook is defined here for ATM LANE */
  int (*br_fdb_test_addr_hook)(struct net_device *dev,
  			     unsigned char *addr) __read_mostly;
  EXPORT_SYMBOL_GPL(br_fdb_test_addr_hook);
  #endif
  
  static inline struct sk_buff *
  sch_handle_ingress(struct sk_buff *skb, struct packet_type **pt_prev, int *ret,
  		   struct net_device *orig_dev)
  {
  #ifdef CONFIG_NET_CLS_ACT
  	struct mini_Qdisc *miniq = rcu_dereference_bh(skb->dev->miniq_ingress);
  	struct tcf_result cl_res;
  
  	/* If there's at least one ingress present somewhere (so
  	 * we get here via enabled static key), remaining devices
  	 * that are not configured with an ingress qdisc will bail
  	 * out here.
  	 */
  	if (!miniq)
  		return skb;
  
  	if (*pt_prev) {
  		*ret = deliver_skb(skb, *pt_prev, orig_dev);
  		*pt_prev = NULL;
  	}
  
  	qdisc_skb_cb(skb)->pkt_len = skb->len;
  	skb->tc_at_ingress = 1;
  	mini_qdisc_bstats_cpu_update(miniq, skb);
  
  	switch (tcf_classify(skb, miniq->filter_list, &cl_res, false)) {
  	case TC_ACT_OK:
  	case TC_ACT_RECLASSIFY:
  		skb->tc_index = TC_H_MIN(cl_res.classid);
  		break;
  	case TC_ACT_SHOT:
  		mini_qdisc_qstats_cpu_drop(miniq);
  		kfree_skb(skb);
  		return NULL;
  	case TC_ACT_STOLEN:
  	case TC_ACT_QUEUED:
  	case TC_ACT_TRAP:
  		consume_skb(skb);
  		return NULL;
  	case TC_ACT_REDIRECT:
  		/* skb_mac_header check was done by cls/act_bpf, so
  		 * we can safely push the L2 header back before
  		 * redirecting to another netdev
  		 */
  		__skb_push(skb, skb->mac_len);
  		skb_do_redirect(skb);
  		return NULL;
  	case TC_ACT_CONSUMED:
  		return NULL;
  	default:
  		break;
  	}
  #endif /* CONFIG_NET_CLS_ACT */
  	return skb;
  }
  
  /**
   *	netdev_is_rx_handler_busy - check if receive handler is registered
   *	@dev: device to check
   *
   *	Check if a receive handler is already registered for a given device.
   *	Return true if there one.
   *
   *	The caller must hold the rtnl_mutex.
   */
  bool netdev_is_rx_handler_busy(struct net_device *dev)
  {
  	ASSERT_RTNL();
  	return dev && rtnl_dereference(dev->rx_handler);
  }
  EXPORT_SYMBOL_GPL(netdev_is_rx_handler_busy);
  
  /**
   *	netdev_rx_handler_register - register receive handler
   *	@dev: device to register a handler for
   *	@rx_handler: receive handler to register
   *	@rx_handler_data: data pointer that is used by rx handler
   *
   *	Register a receive handler for a device. This handler will then be
   *	called from __netif_receive_skb. A negative errno code is returned
   *	on a failure.
   *
   *	The caller must hold the rtnl_mutex.
   *
   *	For a general description of rx_handler, see enum rx_handler_result.
   */
  int netdev_rx_handler_register(struct net_device *dev,
  			       rx_handler_func_t *rx_handler,
  			       void *rx_handler_data)
  {
  	if (netdev_is_rx_handler_busy(dev))
  		return -EBUSY;
  
  	if (dev->priv_flags & IFF_NO_RX_HANDLER)
  		return -EINVAL;
  
  	/* Note: rx_handler_data must be set before rx_handler */
  	rcu_assign_pointer(dev->rx_handler_data, rx_handler_data);
  	rcu_assign_pointer(dev->rx_handler, rx_handler);
  
  	return 0;
  }
  EXPORT_SYMBOL_GPL(netdev_rx_handler_register);
  
  /**
   *	netdev_rx_handler_unregister - unregister receive handler
   *	@dev: device to unregister a handler from
   *
   *	Unregister a receive handler from a device.
   *
   *	The caller must hold the rtnl_mutex.
   */
  void netdev_rx_handler_unregister(struct net_device *dev)
  {
  
  	ASSERT_RTNL();
  	RCU_INIT_POINTER(dev->rx_handler, NULL);
  	/* a reader seeing a non NULL rx_handler in a rcu_read_lock()
  	 * section has a guarantee to see a non NULL rx_handler_data
  	 * as well.
  	 */
  	synchronize_net();
  	RCU_INIT_POINTER(dev->rx_handler_data, NULL);
  }
  EXPORT_SYMBOL_GPL(netdev_rx_handler_unregister);
  
  /*
   * Limit the use of PFMEMALLOC reserves to those protocols that implement
   * the special handling of PFMEMALLOC skbs.
   */
  static bool skb_pfmemalloc_protocol(struct sk_buff *skb)
  {
  	switch (skb->protocol) {
  	case htons(ETH_P_ARP):
  	case htons(ETH_P_IP):
  	case htons(ETH_P_IPV6):
  	case htons(ETH_P_8021Q):
  	case htons(ETH_P_8021AD):
  		return true;
  	default:
  		return false;
  	}
  }
  
  static inline int nf_ingress(struct sk_buff *skb, struct packet_type **pt_prev,
  			     int *ret, struct net_device *orig_dev)
  {
  #ifdef CONFIG_NETFILTER_INGRESS
  	if (nf_hook_ingress_active(skb)) {
  		int ingress_retval;
  
  		if (*pt_prev) {
  			*ret = deliver_skb(skb, *pt_prev, orig_dev);
  			*pt_prev = NULL;
  		}
  
  		rcu_read_lock();
  		ingress_retval = nf_hook_ingress(skb);
  		rcu_read_unlock();
  		return ingress_retval;
  	}
  #endif /* CONFIG_NETFILTER_INGRESS */
  	return 0;
  }
  
  static int __netif_receive_skb_core(struct sk_buff **pskb, bool pfmemalloc,
  				    struct packet_type **ppt_prev)
  {
  	struct packet_type *ptype, *pt_prev;
  	rx_handler_func_t *rx_handler;
  	struct sk_buff *skb = *pskb;
  	struct net_device *orig_dev;
  	bool deliver_exact = false;
  	int ret = NET_RX_DROP;
  	__be16 type;
  
  	net_timestamp_check(!netdev_tstamp_prequeue, skb);
  
  	trace_netif_receive_skb(skb);
  
  	orig_dev = skb->dev;
  
  	skb_reset_network_header(skb);
  	if (!skb_transport_header_was_set(skb))
  		skb_reset_transport_header(skb);
  	skb_reset_mac_len(skb);
  
  	pt_prev = NULL;
  
  another_round:
  	skb->skb_iif = skb->dev->ifindex;
  
  	__this_cpu_inc(softnet_data.processed);
  
  	if (static_branch_unlikely(&generic_xdp_needed_key)) {
  		int ret2;
  
  		preempt_disable();
  		ret2 = do_xdp_generic(rcu_dereference(skb->dev->xdp_prog), skb);
  		preempt_enable();
  
  		if (ret2 != XDP_PASS) {
  			ret = NET_RX_DROP;
  			goto out;
  		}
  		skb_reset_mac_len(skb);
  	}
  
  	if (skb->protocol == cpu_to_be16(ETH_P_8021Q) ||
  	    skb->protocol == cpu_to_be16(ETH_P_8021AD)) {
  		skb = skb_vlan_untag(skb);
  		if (unlikely(!skb))
  			goto out;
  	}
  
  	if (skb_skip_tc_classify(skb))
  		goto skip_classify;
  
  	if (pfmemalloc)
  		goto skip_taps;
  
  	list_for_each_entry_rcu(ptype, &ptype_all, list) {
  		if (pt_prev)
  			ret = deliver_skb(skb, pt_prev, orig_dev);
  		pt_prev = ptype;
  	}
  
  	list_for_each_entry_rcu(ptype, &skb->dev->ptype_all, list) {
  		if (pt_prev)
  			ret = deliver_skb(skb, pt_prev, orig_dev);
  		pt_prev = ptype;
  	}
  
  skip_taps:
  #ifdef CONFIG_NET_INGRESS
  	if (static_branch_unlikely(&ingress_needed_key)) {
  		skb = sch_handle_ingress(skb, &pt_prev, &ret, orig_dev);
  		if (!skb)
  			goto out;
  
  		if (nf_ingress(skb, &pt_prev, &ret, orig_dev) < 0)
  			goto out;
  	}
  #endif
  	skb_reset_redirect(skb);
  skip_classify:
  	if (pfmemalloc && !skb_pfmemalloc_protocol(skb))
  		goto drop;
  
  	if (skb_vlan_tag_present(skb)) {
  		if (pt_prev) {
  			ret = deliver_skb(skb, pt_prev, orig_dev);
  			pt_prev = NULL;
  		}
  		if (vlan_do_receive(&skb))
  			goto another_round;
  		else if (unlikely(!skb))
  			goto out;
  	}
  
  	rx_handler = rcu_dereference(skb->dev->rx_handler);
  	if (rx_handler) {
  		if (pt_prev) {
  			ret = deliver_skb(skb, pt_prev, orig_dev);
  			pt_prev = NULL;
  		}
  		switch (rx_handler(&skb)) {
  		case RX_HANDLER_CONSUMED:
  			ret = NET_RX_SUCCESS;
  			goto out;
  		case RX_HANDLER_ANOTHER:
  			goto another_round;
  		case RX_HANDLER_EXACT:
  			deliver_exact = true;
  		case RX_HANDLER_PASS:
  			break;
  		default:
  			BUG();
  		}
  	}
  
  	if (unlikely(skb_vlan_tag_present(skb))) {
  check_vlan_id:
  		if (skb_vlan_tag_get_id(skb)) {
  			/* Vlan id is non 0 and vlan_do_receive() above couldn't
  			 * find vlan device.
  			 */
  			skb->pkt_type = PACKET_OTHERHOST;
  		} else if (skb->protocol == cpu_to_be16(ETH_P_8021Q) ||
  			   skb->protocol == cpu_to_be16(ETH_P_8021AD)) {
  			/* Outer header is 802.1P with vlan 0, inner header is
  			 * 802.1Q or 802.1AD and vlan_do_receive() above could
  			 * not find vlan dev for vlan id 0.
  			 */
  			__vlan_hwaccel_clear_tag(skb);
  			skb = skb_vlan_untag(skb);
  			if (unlikely(!skb))
  				goto out;
  			if (vlan_do_receive(&skb))
  				/* After stripping off 802.1P header with vlan 0
  				 * vlan dev is found for inner header.
  				 */
  				goto another_round;
  			else if (unlikely(!skb))
  				goto out;
  			else
  				/* We have stripped outer 802.1P vlan 0 header.
  				 * But could not find vlan dev.
  				 * check again for vlan id to set OTHERHOST.
  				 */
  				goto check_vlan_id;
  		}
  		/* Note: we might in the future use prio bits
  		 * and set skb->priority like in vlan_do_receive()
  		 * For the time being, just ignore Priority Code Point
  		 */
  		__vlan_hwaccel_clear_tag(skb);
  	}
  
  	type = skb->protocol;
  
  	/* deliver only exact match when indicated */
  	if (likely(!deliver_exact)) {
  		deliver_ptype_list_skb(skb, &pt_prev, orig_dev, type,
  				       &ptype_base[ntohs(type) &
  						   PTYPE_HASH_MASK]);
  	}
  
  	deliver_ptype_list_skb(skb, &pt_prev, orig_dev, type,
  			       &orig_dev->ptype_specific);
  
  	if (unlikely(skb->dev != orig_dev)) {
  		deliver_ptype_list_skb(skb, &pt_prev, orig_dev, type,
  				       &skb->dev->ptype_specific);
  	}
  
  	if (pt_prev) {
  		if (unlikely(skb_orphan_frags_rx(skb, GFP_ATOMIC)))
  			goto drop;
  		*ppt_prev = pt_prev;
  	} else {
  drop:
  		if (!deliver_exact)
  			atomic_long_inc(&skb->dev->rx_dropped);
  		else
  			atomic_long_inc(&skb->dev->rx_nohandler);
  		kfree_skb(skb);
  		/* Jamal, now you will not able to escape explaining
  		 * me how you were going to use this. :-)
  		 */
  		ret = NET_RX_DROP;
  	}
  
  out:
  	/* The invariant here is that if *ppt_prev is not NULL
  	 * then skb should also be non-NULL.
  	 *
  	 * Apparently *ppt_prev assignment above holds this invariant due to
  	 * skb dereferencing near it.
  	 */
  	*pskb = skb;
  	return ret;
  }
  
  static int __netif_receive_skb_one_core(struct sk_buff *skb, bool pfmemalloc)
  {
  	struct net_device *orig_dev = skb->dev;
  	struct packet_type *pt_prev = NULL;
  	int ret;
  
  	ret = __netif_receive_skb_core(&skb, pfmemalloc, &pt_prev);
  	if (pt_prev)
  		ret = INDIRECT_CALL_INET(pt_prev->func, ipv6_rcv, ip_rcv, skb,
  					 skb->dev, pt_prev, orig_dev);
  	return ret;
  }
  
  /**
   *	netif_receive_skb_core - special purpose version of netif_receive_skb
   *	@skb: buffer to process
   *
   *	More direct receive version of netif_receive_skb().  It should
   *	only be used by callers that have a need to skip RPS and Generic XDP.
   *	Caller must also take care of handling if (page_is_)pfmemalloc.
   *
   *	This function may only be called from softirq context and interrupts
   *	should be enabled.
   *
   *	Return values (usually ignored):
   *	NET_RX_SUCCESS: no congestion
   *	NET_RX_DROP: packet was dropped
   */
  int netif_receive_skb_core(struct sk_buff *skb)
  {
  	int ret;
  
  	rcu_read_lock();
  	ret = __netif_receive_skb_one_core(skb, false);
  	rcu_read_unlock();
  
  	return ret;
  }
  EXPORT_SYMBOL(netif_receive_skb_core);
  
  static inline void __netif_receive_skb_list_ptype(struct list_head *head,
  						  struct packet_type *pt_prev,
  						  struct net_device *orig_dev)
  {
  	struct sk_buff *skb, *next;
  
  	if (!pt_prev)
  		return;
  	if (list_empty(head))
  		return;
  	if (pt_prev->list_func != NULL)
  		INDIRECT_CALL_INET(pt_prev->list_func, ipv6_list_rcv,
  				   ip_list_rcv, head, pt_prev, orig_dev);
  	else
  		list_for_each_entry_safe(skb, next, head, list) {
  			skb_list_del_init(skb);
  			pt_prev->func(skb, skb->dev, pt_prev, orig_dev);
  		}
  }
  
  static void __netif_receive_skb_list_core(struct list_head *head, bool pfmemalloc)
  {
  	/* Fast-path assumptions:
  	 * - There is no RX handler.
  	 * - Only one packet_type matches.
  	 * If either of these fails, we will end up doing some per-packet
  	 * processing in-line, then handling the 'last ptype' for the whole
  	 * sublist.  This can't cause out-of-order delivery to any single ptype,
  	 * because the 'last ptype' must be constant across the sublist, and all
  	 * other ptypes are handled per-packet.
  	 */
  	/* Current (common) ptype of sublist */
  	struct packet_type *pt_curr = NULL;
  	/* Current (common) orig_dev of sublist */
  	struct net_device *od_curr = NULL;
  	struct list_head sublist;
  	struct sk_buff *skb, *next;
  
  	INIT_LIST_HEAD(&sublist);
  	list_for_each_entry_safe(skb, next, head, list) {
  		struct net_device *orig_dev = skb->dev;
  		struct packet_type *pt_prev = NULL;
  
  		skb_list_del_init(skb);
  		__netif_receive_skb_core(&skb, pfmemalloc, &pt_prev);
  		if (!pt_prev)
  			continue;
  		if (pt_curr != pt_prev || od_curr != orig_dev) {
  			/* dispatch old sublist */
  			__netif_receive_skb_list_ptype(&sublist, pt_curr, od_curr);
  			/* start new sublist */
  			INIT_LIST_HEAD(&sublist);
  			pt_curr = pt_prev;
  			od_curr = orig_dev;
  		}
  		list_add_tail(&skb->list, &sublist);
  	}
  
  	/* dispatch final sublist */
  	__netif_receive_skb_list_ptype(&sublist, pt_curr, od_curr);
  }
  
  static int __netif_receive_skb(struct sk_buff *skb)
  {
  	int ret;
  
  	if (sk_memalloc_socks() && skb_pfmemalloc(skb)) {
  		unsigned int noreclaim_flag;
  
  		/*
  		 * PFMEMALLOC skbs are special, they should
  		 * - be delivered to SOCK_MEMALLOC sockets only
  		 * - stay away from userspace
  		 * - have bounded memory usage
  		 *
  		 * Use PF_MEMALLOC as this saves us from propagating the allocation
  		 * context down to all allocation sites.
  		 */
  		noreclaim_flag = memalloc_noreclaim_save();
  		ret = __netif_receive_skb_one_core(skb, true);
  		memalloc_noreclaim_restore(noreclaim_flag);
  	} else
  		ret = __netif_receive_skb_one_core(skb, false);
  
  	return ret;
  }
  
  static void __netif_receive_skb_list(struct list_head *head)
  {
  	unsigned long noreclaim_flag = 0;
  	struct sk_buff *skb, *next;
  	bool pfmemalloc = false; /* Is current sublist PF_MEMALLOC? */
  
  	list_for_each_entry_safe(skb, next, head, list) {
  		if ((sk_memalloc_socks() && skb_pfmemalloc(skb)) != pfmemalloc) {
  			struct list_head sublist;
  
  			/* Handle the previous sublist */
  			list_cut_before(&sublist, head, &skb->list);
  			if (!list_empty(&sublist))
  				__netif_receive_skb_list_core(&sublist, pfmemalloc);
  			pfmemalloc = !pfmemalloc;
  			/* See comments in __netif_receive_skb */
  			if (pfmemalloc)
  				noreclaim_flag = memalloc_noreclaim_save();
  			else
  				memalloc_noreclaim_restore(noreclaim_flag);
  		}
  	}
  	/* Handle the remaining sublist */
  	if (!list_empty(head))
  		__netif_receive_skb_list_core(head, pfmemalloc);
  	/* Restore pflags */
  	if (pfmemalloc)
  		memalloc_noreclaim_restore(noreclaim_flag);
  }
  
  static int generic_xdp_install(struct net_device *dev, struct netdev_bpf *xdp)
  {
  	struct bpf_prog *old = rtnl_dereference(dev->xdp_prog);
  	struct bpf_prog *new = xdp->prog;
  	int ret = 0;
  
  	switch (xdp->command) {
  	case XDP_SETUP_PROG:
  		rcu_assign_pointer(dev->xdp_prog, new);
  		if (old)
  			bpf_prog_put(old);
  
  		if (old && !new) {
  			static_branch_dec(&generic_xdp_needed_key);
  		} else if (new && !old) {
  			static_branch_inc(&generic_xdp_needed_key);
  			dev_disable_lro(dev);
  			dev_disable_gro_hw(dev);
  		}
  		break;
  
  	case XDP_QUERY_PROG:
  		xdp->prog_id = old ? old->aux->id : 0;
  		break;
  
  	default:
  		ret = -EINVAL;
  		break;
  	}
  
  	return ret;
  }
  
  static int netif_receive_skb_internal(struct sk_buff *skb)
  {
  	int ret;
  
  	net_timestamp_check(netdev_tstamp_prequeue, skb);
  
  	if (skb_defer_rx_timestamp(skb))
  		return NET_RX_SUCCESS;
  
  	rcu_read_lock();
  #ifdef CONFIG_RPS
  	if (static_branch_unlikely(&rps_needed)) {
  		struct rps_dev_flow voidflow, *rflow = &voidflow;
  		int cpu = get_rps_cpu(skb->dev, skb, &rflow);
  
  		if (cpu >= 0) {
  			ret = enqueue_to_backlog(skb, cpu, &rflow->last_qtail);
  			rcu_read_unlock();
  			return ret;
  		}
  	}
  #endif
  	ret = __netif_receive_skb(skb);
  	rcu_read_unlock();
  	return ret;
  }
  
  static void netif_receive_skb_list_internal(struct list_head *head)
  {
  	struct sk_buff *skb, *next;
  	struct list_head sublist;
  
  	INIT_LIST_HEAD(&sublist);
  	list_for_each_entry_safe(skb, next, head, list) {
  		net_timestamp_check(netdev_tstamp_prequeue, skb);
  		skb_list_del_init(skb);
  		if (!skb_defer_rx_timestamp(skb))
  			list_add_tail(&skb->list, &sublist);
  	}
  	list_splice_init(&sublist, head);
  
  	rcu_read_lock();
  #ifdef CONFIG_RPS
  	if (static_branch_unlikely(&rps_needed)) {
  		list_for_each_entry_safe(skb, next, head, list) {
  			struct rps_dev_flow voidflow, *rflow = &voidflow;
  			int cpu = get_rps_cpu(skb->dev, skb, &rflow);
  
  			if (cpu >= 0) {
  				/* Will be handled, remove from list */
  				skb_list_del_init(skb);
  				enqueue_to_backlog(skb, cpu, &rflow->last_qtail);
  			}
  		}
  	}
  #endif
  	__netif_receive_skb_list(head);
  	rcu_read_unlock();
  }
  
  /**
   *	netif_receive_skb - process receive buffer from network
   *	@skb: buffer to process
   *
   *	netif_receive_skb() is the main receive data processing function.
   *	It always succeeds. The buffer may be dropped during processing
   *	for congestion control or by the protocol layers.
   *
   *	This function may only be called from softirq context and interrupts
   *	should be enabled.
   *
   *	Return values (usually ignored):
   *	NET_RX_SUCCESS: no congestion
   *	NET_RX_DROP: packet was dropped
   */
  int netif_receive_skb(struct sk_buff *skb)
  {
  	int ret;
  
  	trace_netif_receive_skb_entry(skb);
  
  	ret = netif_receive_skb_internal(skb);
  	trace_netif_receive_skb_exit(ret);
  
  	return ret;
  }
  EXPORT_SYMBOL(netif_receive_skb);
  
  /**
   *	netif_receive_skb_list - process many receive buffers from network
   *	@head: list of skbs to process.
   *
   *	Since return value of netif_receive_skb() is normally ignored, and
   *	wouldn't be meaningful for a list, this function returns void.
   *
   *	This function may only be called from softirq context and interrupts
   *	should be enabled.
   */
  void netif_receive_skb_list(struct list_head *head)
  {
  	struct sk_buff *skb;
  
  	if (list_empty(head))
  		return;
  	if (trace_netif_receive_skb_list_entry_enabled()) {
  		list_for_each_entry(skb, head, list)
  			trace_netif_receive_skb_list_entry(skb);
  	}
  	netif_receive_skb_list_internal(head);
  	trace_netif_receive_skb_list_exit(0);
  }
  EXPORT_SYMBOL(netif_receive_skb_list);
  
  DEFINE_PER_CPU(struct work_struct, flush_works);
  
  /* Network device is going away, flush any packets still pending */
  static void flush_backlog(struct work_struct *work)
  {
  	struct sk_buff *skb, *tmp;
  	struct softnet_data *sd;
  
  	local_bh_disable();
  	sd = this_cpu_ptr(&softnet_data);
  
  	local_irq_disable();
  	rps_lock(sd);
  	skb_queue_walk_safe(&sd->input_pkt_queue, skb, tmp) {
  		if (skb->dev->reg_state == NETREG_UNREGISTERING) {
  			__skb_unlink(skb, &sd->input_pkt_queue);
  			dev_kfree_skb_irq(skb);
  			input_queue_head_incr(sd);
  		}
  	}
  	rps_unlock(sd);
  	local_irq_enable();
  
  	skb_queue_walk_safe(&sd->process_queue, skb, tmp) {
  		if (skb->dev->reg_state == NETREG_UNREGISTERING) {
  			__skb_unlink(skb, &sd->process_queue);
  			kfree_skb(skb);
  			input_queue_head_incr(sd);
  		}
  	}
  	local_bh_enable();
  }
  
  static void flush_all_backlogs(void)
  {
  	unsigned int cpu;
  
  	get_online_cpus();
  
  	for_each_online_cpu(cpu)
  		queue_work_on(cpu, system_highpri_wq,
  			      per_cpu_ptr(&flush_works, cpu));
  
  	for_each_online_cpu(cpu)
  		flush_work(per_cpu_ptr(&flush_works, cpu));
  
  	put_online_cpus();
  }
  
  /* Pass the currently batched GRO_NORMAL SKBs up to the stack. */
  static void gro_normal_list(struct napi_struct *napi)
  {
  	if (!napi->rx_count)
  		return;
  	netif_receive_skb_list_internal(&napi->rx_list);
  	INIT_LIST_HEAD(&napi->rx_list);
  	napi->rx_count = 0;
  }
  
  /* Queue one GRO_NORMAL SKB up for list processing. If batch size exceeded,
   * pass the whole batch up to the stack.
   */
  static void gro_normal_one(struct napi_struct *napi, struct sk_buff *skb)
  {
  	list_add_tail(&skb->list, &napi->rx_list);
  	if (++napi->rx_count >= gro_normal_batch)
  		gro_normal_list(napi);
  }
  
  INDIRECT_CALLABLE_DECLARE(int inet_gro_complete(struct sk_buff *, int));
  INDIRECT_CALLABLE_DECLARE(int ipv6_gro_complete(struct sk_buff *, int));
  static int napi_gro_complete(struct napi_struct *napi, struct sk_buff *skb)
  {
  	struct packet_offload *ptype;
  	__be16 type = skb->protocol;
  	struct list_head *head = &offload_base;
  	int err = -ENOENT;
  
  	BUILD_BUG_ON(sizeof(struct napi_gro_cb) > sizeof(skb->cb));
  
  	if (NAPI_GRO_CB(skb)->count == 1) {
  		skb_shinfo(skb)->gso_size = 0;
  		goto out;
  	}
  
  	rcu_read_lock();
  	list_for_each_entry_rcu(ptype, head, list) {
  		if (ptype->type != type || !ptype->callbacks.gro_complete)
  			continue;
  
  		err = INDIRECT_CALL_INET(ptype->callbacks.gro_complete,
  					 ipv6_gro_complete, inet_gro_complete,
  					 skb, 0);
  		break;
  	}
  	rcu_read_unlock();
  
  	if (err) {
  		WARN_ON(&ptype->list == head);
  		kfree_skb(skb);
  		return NET_RX_SUCCESS;
  	}
  
  out:
  	gro_normal_one(napi, skb);
  	return NET_RX_SUCCESS;
  }
  
  static void __napi_gro_flush_chain(struct napi_struct *napi, u32 index,
  				   bool flush_old)
  {
  	struct list_head *head = &napi->gro_hash[index].list;
  	struct sk_buff *skb, *p;
  
  	list_for_each_entry_safe_reverse(skb, p, head, list) {
  		if (flush_old && NAPI_GRO_CB(skb)->age == jiffies)
  			return;
  		skb_list_del_init(skb);
  		napi_gro_complete(napi, skb);
  		napi->gro_hash[index].count--;
  	}
  
  	if (!napi->gro_hash[index].count)
  		__clear_bit(index, &napi->gro_bitmask);
  }
  
  /* napi->gro_hash[].list contains packets ordered by age.
   * youngest packets at the head of it.
   * Complete skbs in reverse order to reduce latencies.
   */
  void napi_gro_flush(struct napi_struct *napi, bool flush_old)
  {
  	unsigned long bitmask = napi->gro_bitmask;
  	unsigned int i, base = ~0U;
  
  	while ((i = ffs(bitmask)) != 0) {
  		bitmask >>= i;
  		base += i;
  		__napi_gro_flush_chain(napi, base, flush_old);
  	}
  }
  EXPORT_SYMBOL(napi_gro_flush);
  
  static struct list_head *gro_list_prepare(struct napi_struct *napi,
  					  struct sk_buff *skb)
  {
  	unsigned int maclen = skb->dev->hard_header_len;
  	u32 hash = skb_get_hash_raw(skb);
  	struct list_head *head;
  	struct sk_buff *p;
  
  	head = &napi->gro_hash[hash & (GRO_HASH_BUCKETS - 1)].list;
  	list_for_each_entry(p, head, list) {
  		unsigned long diffs;
  
  		NAPI_GRO_CB(p)->flush = 0;
  
  		if (hash != skb_get_hash_raw(p)) {
  			NAPI_GRO_CB(p)->same_flow = 0;
  			continue;
  		}
  
  		diffs = (unsigned long)p->dev ^ (unsigned long)skb->dev;
  		diffs |= skb_vlan_tag_present(p) ^ skb_vlan_tag_present(skb);
  		if (skb_vlan_tag_present(p))
  			diffs |= p->vlan_tci ^ skb->vlan_tci;
  		diffs |= skb_metadata_dst_cmp(p, skb);
  		diffs |= skb_metadata_differs(p, skb);
  		if (maclen == ETH_HLEN)
  			diffs |= compare_ether_header(skb_mac_header(p),
  						      skb_mac_header(skb));
  		else if (!diffs)
  			diffs = memcmp(skb_mac_header(p),
  				       skb_mac_header(skb),
  				       maclen);
  		NAPI_GRO_CB(p)->same_flow = !diffs;
  	}
  
  	return head;
  }
  
  static void skb_gro_reset_offset(struct sk_buff *skb)
  {
  	const struct skb_shared_info *pinfo = skb_shinfo(skb);
  	const skb_frag_t *frag0 = &pinfo->frags[0];
  
  	NAPI_GRO_CB(skb)->data_offset = 0;
  	NAPI_GRO_CB(skb)->frag0 = NULL;
  	NAPI_GRO_CB(skb)->frag0_len = 0;
  
  	if (skb_mac_header(skb) == skb_tail_pointer(skb) &&
  	    pinfo->nr_frags &&
  	    !PageHighMem(skb_frag_page(frag0))) {
  		NAPI_GRO_CB(skb)->frag0 = skb_frag_address(frag0);
  		NAPI_GRO_CB(skb)->frag0_len = min_t(unsigned int,
  						    skb_frag_size(frag0),
  						    skb->end - skb->tail);
  	}
  }
  
  static void gro_pull_from_frag0(struct sk_buff *skb, int grow)
  {
  	struct skb_shared_info *pinfo = skb_shinfo(skb);
  
  	BUG_ON(skb->end - skb->tail < grow);
  
  	memcpy(skb_tail_pointer(skb), NAPI_GRO_CB(skb)->frag0, grow);
  
  	skb->data_len -= grow;
  	skb->tail += grow;
  
  	skb_frag_off_add(&pinfo->frags[0], grow);
  	skb_frag_size_sub(&pinfo->frags[0], grow);
  
  	if (unlikely(!skb_frag_size(&pinfo->frags[0]))) {
  		skb_frag_unref(skb, 0);
  		memmove(pinfo->frags, pinfo->frags + 1,
  			--pinfo->nr_frags * sizeof(pinfo->frags[0]));
  	}
  }
  
  static void gro_flush_oldest(struct napi_struct *napi, struct list_head *head)
  {
  	struct sk_buff *oldest;
  
  	oldest = list_last_entry(head, struct sk_buff, list);
  
  	/* We are called with head length >= MAX_GRO_SKBS, so this is
  	 * impossible.
  	 */
  	if (WARN_ON_ONCE(!oldest))
  		return;
  
  	/* Do not adjust napi->gro_hash[].count, caller is adding a new
  	 * SKB to the chain.
  	 */
  	skb_list_del_init(oldest);
  	napi_gro_complete(napi, oldest);
  }
  
  INDIRECT_CALLABLE_DECLARE(struct sk_buff *inet_gro_receive(struct list_head *,
  							   struct sk_buff *));
  INDIRECT_CALLABLE_DECLARE(struct sk_buff *ipv6_gro_receive(struct list_head *,
  							   struct sk_buff *));
  static enum gro_result dev_gro_receive(struct napi_struct *napi, struct sk_buff *skb)
  {
  	u32 hash = skb_get_hash_raw(skb) & (GRO_HASH_BUCKETS - 1);
  	struct list_head *head = &offload_base;
  	struct packet_offload *ptype;
  	__be16 type = skb->protocol;
  	struct list_head *gro_head;
  	struct sk_buff *pp = NULL;
  	enum gro_result ret;
  	int same_flow;
  	int grow;
  
  	if (netif_elide_gro(skb->dev))
  		goto normal;
  
  	gro_head = gro_list_prepare(napi, skb);
  
  	rcu_read_lock();
  	list_for_each_entry_rcu(ptype, head, list) {
  		if (ptype->type != type || !ptype->callbacks.gro_receive)
  			continue;
  
  		skb_set_network_header(skb, skb_gro_offset(skb));
  		skb_reset_mac_len(skb);
  		NAPI_GRO_CB(skb)->same_flow = 0;
  		NAPI_GRO_CB(skb)->flush = skb_is_gso(skb) || skb_has_frag_list(skb);
  		NAPI_GRO_CB(skb)->free = 0;
  		NAPI_GRO_CB(skb)->encap_mark = 0;
  		NAPI_GRO_CB(skb)->recursion_counter = 0;
  		NAPI_GRO_CB(skb)->is_fou = 0;
  		NAPI_GRO_CB(skb)->is_atomic = 1;
  		NAPI_GRO_CB(skb)->gro_remcsum_start = 0;
  
  		/* Setup for GRO checksum validation */
  		switch (skb->ip_summed) {
  		case CHECKSUM_COMPLETE:
  			NAPI_GRO_CB(skb)->csum = skb->csum;
  			NAPI_GRO_CB(skb)->csum_valid = 1;
  			NAPI_GRO_CB(skb)->csum_cnt = 0;
  			break;
  		case CHECKSUM_UNNECESSARY:
  			NAPI_GRO_CB(skb)->csum_cnt = skb->csum_level + 1;
  			NAPI_GRO_CB(skb)->csum_valid = 0;
  			break;
  		default:
  			NAPI_GRO_CB(skb)->csum_cnt = 0;
  			NAPI_GRO_CB(skb)->csum_valid = 0;
  		}
  
  		pp = INDIRECT_CALL_INET(ptype->callbacks.gro_receive,
  					ipv6_gro_receive, inet_gro_receive,
  					gro_head, skb);
  		break;
  	}
  	rcu_read_unlock();
  
  	if (&ptype->list == head)
  		goto normal;
  
  	if (IS_ERR(pp) && PTR_ERR(pp) == -EINPROGRESS) {
  		ret = GRO_CONSUMED;
  		goto ok;
  	}
  
  	same_flow = NAPI_GRO_CB(skb)->same_flow;
  	ret = NAPI_GRO_CB(skb)->free ? GRO_MERGED_FREE : GRO_MERGED;
  
  	if (pp) {
  		skb_list_del_init(pp);
  		napi_gro_complete(napi, pp);
  		napi->gro_hash[hash].count--;
  	}
  
  	if (same_flow)
  		goto ok;
  
  	if (NAPI_GRO_CB(skb)->flush)
  		goto normal;
  
  	if (unlikely(napi->gro_hash[hash].count >= MAX_GRO_SKBS)) {
  		gro_flush_oldest(napi, gro_head);
  	} else {
  		napi->gro_hash[hash].count++;
  	}
  	NAPI_GRO_CB(skb)->count = 1;
  	NAPI_GRO_CB(skb)->age = jiffies;
  	NAPI_GRO_CB(skb)->last = skb;
  	skb_shinfo(skb)->gso_size = skb_gro_len(skb);
  	list_add(&skb->list, gro_head);
  	ret = GRO_HELD;
  
  pull:
  	grow = skb_gro_offset(skb) - skb_headlen(skb);
  	if (grow > 0)
  		gro_pull_from_frag0(skb, grow);
  ok:
  	if (napi->gro_hash[hash].count) {
  		if (!test_bit(hash, &napi->gro_bitmask))
  			__set_bit(hash, &napi->gro_bitmask);
  	} else if (test_bit(hash, &napi->gro_bitmask)) {
  		__clear_bit(hash, &napi->gro_bitmask);
  	}
  
  	return ret;
  
  normal:
  	ret = GRO_NORMAL;
  	goto pull;
  }
  
  struct packet_offload *gro_find_receive_by_type(__be16 type)
  {
  	struct list_head *offload_head = &offload_base;
  	struct packet_offload *ptype;
  
  	list_for_each_entry_rcu(ptype, offload_head, list) {
  		if (ptype->type != type || !ptype->callbacks.gro_receive)
  			continue;
  		return ptype;
  	}
  	return NULL;
  }
  EXPORT_SYMBOL(gro_find_receive_by_type);
  
  struct packet_offload *gro_find_complete_by_type(__be16 type)
  {
  	struct list_head *offload_head = &offload_base;
  	struct packet_offload *ptype;
  
  	list_for_each_entry_rcu(ptype, offload_head, list) {
  		if (ptype->type != type || !ptype->callbacks.gro_complete)
  			continue;
  		return ptype;
  	}
  	return NULL;
  }
  EXPORT_SYMBOL(gro_find_complete_by_type);
  
  static void napi_skb_free_stolen_head(struct sk_buff *skb)
  {
  	skb_dst_drop(skb);
  	skb_ext_put(skb);
  	kmem_cache_free(skbuff_head_cache, skb);
  }
  
  static gro_result_t napi_skb_finish(struct napi_struct *napi,
  				    struct sk_buff *skb,
  				    gro_result_t ret)
  {
  	switch (ret) {
  	case GRO_NORMAL:
  		gro_normal_one(napi, skb);
  		break;
  
  	case GRO_DROP:
  		kfree_skb(skb);
  		break;
  
  	case GRO_MERGED_FREE:
  		if (NAPI_GRO_CB(skb)->free == NAPI_GRO_FREE_STOLEN_HEAD)
  			napi_skb_free_stolen_head(skb);
  		else
  			__kfree_skb(skb);
  		break;
  
  	case GRO_HELD:
  	case GRO_MERGED:
  	case GRO_CONSUMED:
  		break;
  	}
  
  	return ret;
  }
  
  gro_result_t napi_gro_receive(struct napi_struct *napi, struct sk_buff *skb)
  {
  	gro_result_t ret;
  
  	skb_mark_napi_id(skb, napi);
  	trace_napi_gro_receive_entry(skb);
  
  	skb_gro_reset_offset(skb);
  
  	ret = napi_skb_finish(napi, skb, dev_gro_receive(napi, skb));
  	trace_napi_gro_receive_exit(ret);
  
  	return ret;
  }
  EXPORT_SYMBOL(napi_gro_receive);
  
  static void napi_reuse_skb(struct napi_struct *napi, struct sk_buff *skb)
  {
  	if (unlikely(skb->pfmemalloc)) {
  		consume_skb(skb);
  		return;
  	}
  	__skb_pull(skb, skb_headlen(skb));
  	/* restore the reserve we had after netdev_alloc_skb_ip_align() */
  	skb_reserve(skb, NET_SKB_PAD + NET_IP_ALIGN - skb_headroom(skb));
  	__vlan_hwaccel_clear_tag(skb);
  	skb->dev = napi->dev;
  	skb->skb_iif = 0;
  
  	/* eth_type_trans() assumes pkt_type is PACKET_HOST */
  	skb->pkt_type = PACKET_HOST;
  
  	skb->encapsulation = 0;
  	skb_shinfo(skb)->gso_type = 0;
  	skb->truesize = SKB_TRUESIZE(skb_end_offset(skb));
  	skb_ext_reset(skb);
  
  	napi->skb = skb;
  }
  
  struct sk_buff *napi_get_frags(struct napi_struct *napi)
  {
  	struct sk_buff *skb = napi->skb;
  
  	if (!skb) {
  		skb = napi_alloc_skb(napi, GRO_MAX_HEAD);
  		if (skb) {
  			napi->skb = skb;
  			skb_mark_napi_id(skb, napi);
  		}
  	}
  	return skb;
  }
  EXPORT_SYMBOL(napi_get_frags);
  
  static gro_result_t napi_frags_finish(struct napi_struct *napi,
  				      struct sk_buff *skb,
  				      gro_result_t ret)
  {
  	switch (ret) {
  	case GRO_NORMAL:
  	case GRO_HELD:
  		__skb_push(skb, ETH_HLEN);
  		skb->protocol = eth_type_trans(skb, skb->dev);
  		if (ret == GRO_NORMAL)
  			gro_normal_one(napi, skb);
  		break;
  
  	case GRO_DROP:
  		napi_reuse_skb(napi, skb);
  		break;
  
  	case GRO_MERGED_FREE:
  		if (NAPI_GRO_CB(skb)->free == NAPI_GRO_FREE_STOLEN_HEAD)
  			napi_skb_free_stolen_head(skb);
  		else
  			napi_reuse_skb(napi, skb);
  		break;
  
  	case GRO_MERGED:
  	case GRO_CONSUMED:
  		break;
  	}
  
  	return ret;
  }
  
  /* Upper GRO stack assumes network header starts at gro_offset=0
   * Drivers could call both napi_gro_frags() and napi_gro_receive()
   * We copy ethernet header into skb->data to have a common layout.
   */
  static struct sk_buff *napi_frags_skb(struct napi_struct *napi)
  {
  	struct sk_buff *skb = napi->skb;
  	const struct ethhdr *eth;
  	unsigned int hlen = sizeof(*eth);
  
  	napi->skb = NULL;
  
  	skb_reset_mac_header(skb);
  	skb_gro_reset_offset(skb);
  
  	if (unlikely(skb_gro_header_hard(skb, hlen))) {
  		eth = skb_gro_header_slow(skb, hlen, 0);
  		if (unlikely(!eth)) {
  			net_warn_ratelimited("%s: dropping impossible skb from %s\n",
  					     __func__, napi->dev->name);
  			napi_reuse_skb(napi, skb);
  			return NULL;
  		}
  	} else {
  		eth = (const struct ethhdr *)skb->data;
  		gro_pull_from_frag0(skb, hlen);
  		NAPI_GRO_CB(skb)->frag0 += hlen;
  		NAPI_GRO_CB(skb)->frag0_len -= hlen;
  	}
  	__skb_pull(skb, hlen);
  
  	/*
  	 * This works because the only protocols we care about don't require
  	 * special handling.
  	 * We'll fix it up properly in napi_frags_finish()
  	 */
  	skb->protocol = eth->h_proto;
  
  	return skb;
  }
  
  gro_result_t napi_gro_frags(struct napi_struct *napi)
  {
  	gro_result_t ret;
  	struct sk_buff *skb = napi_frags_skb(napi);
  
  	if (!skb)
  		return GRO_DROP;
  
  	trace_napi_gro_frags_entry(skb);
  
  	ret = napi_frags_finish(napi, skb, dev_gro_receive(napi, skb));
  	trace_napi_gro_frags_exit(ret);
  
  	return ret;
  }
  EXPORT_SYMBOL(napi_gro_frags);
  
  /* Compute the checksum from gro_offset and return the folded value
   * after adding in any pseudo checksum.
   */
  __sum16 __skb_gro_checksum_complete(struct sk_buff *skb)
  {
  	__wsum wsum;
  	__sum16 sum;
  
  	wsum = skb_checksum(skb, skb_gro_offset(skb), skb_gro_len(skb), 0);
  
  	/* NAPI_GRO_CB(skb)->csum holds pseudo checksum */
  	sum = csum_fold(csum_add(NAPI_GRO_CB(skb)->csum, wsum));
  	/* See comments in __skb_checksum_complete(). */
  	if (likely(!sum)) {
  		if (unlikely(skb->ip_summed == CHECKSUM_COMPLETE) &&
  		    !skb->csum_complete_sw)
  			netdev_rx_csum_fault(skb->dev, skb);
  	}
  
  	NAPI_GRO_CB(skb)->csum = wsum;
  	NAPI_GRO_CB(skb)->csum_valid = 1;
  
  	return sum;
  }
  EXPORT_SYMBOL(__skb_gro_checksum_complete);
  
  static void net_rps_send_ipi(struct softnet_data *remsd)
  {
  #ifdef CONFIG_RPS
  	while (remsd) {
  		struct softnet_data *next = remsd->rps_ipi_next;
  
  		if (cpu_online(remsd->cpu))
  			smp_call_function_single_async(remsd->cpu, &remsd->csd);
  		remsd = next;
  	}
  #endif
  }
  
  /*
   * net_rps_action_and_irq_enable sends any pending IPI's for rps.
   * Note: called with local irq disabled, but exits with local irq enabled.
   */
  static void net_rps_action_and_irq_enable(struct softnet_data *sd)
  {
  #ifdef CONFIG_RPS
  	struct softnet_data *remsd = sd->rps_ipi_list;
  
  	if (remsd) {
  		sd->rps_ipi_list = NULL;
  
  		local_irq_enable();
  
  		/* Send pending IPI's to kick RPS processing on remote cpus. */
  		net_rps_send_ipi(remsd);
  	} else
  #endif
  		local_irq_enable();
  }
  
  static bool sd_has_rps_ipi_waiting(struct softnet_data *sd)
  {
  #ifdef CONFIG_RPS
  	return sd->rps_ipi_list != NULL;
  #else
  	return false;
  #endif
  }
  
  static int process_backlog(struct napi_struct *napi, int quota)
  {
  	struct softnet_data *sd = container_of(napi, struct softnet_data, backlog);
  	bool again = true;
  	int work = 0;
  
  	/* Check if we have pending ipi, its better to send them now,
  	 * not waiting net_rx_action() end.
  	 */
  	if (sd_has_rps_ipi_waiting(sd)) {
  		local_irq_disable();
  		net_rps_action_and_irq_enable(sd);
  	}
  
  	napi->weight = dev_rx_weight;
  	while (again) {
  		struct sk_buff *skb;
  
  		while ((skb = __skb_dequeue(&sd->process_queue))) {
  			rcu_read_lock();
  			__netif_receive_skb(skb);
  			rcu_read_unlock();
  			input_queue_head_incr(sd);
  			if (++work >= quota)
  				return work;
  
  		}
  
  		local_irq_disable();
  		rps_lock(sd);
  		if (skb_queue_empty(&sd->input_pkt_queue)) {
  			/*
  			 * Inline a custom version of __napi_complete().
  			 * only current cpu owns and manipulates this napi,
  			 * and NAPI_STATE_SCHED is the only possible flag set
  			 * on backlog.
  			 * We can use a plain write instead of clear_bit(),
  			 * and we dont need an smp_mb() memory barrier.
  			 */
  			napi->state = 0;
  			again = false;
  		} else {
  			skb_queue_splice_tail_init(&sd->input_pkt_queue,
  						   &sd->process_queue);
  		}
  		rps_unlock(sd);
  		local_irq_enable();
  	}
  
  	return work;
  }
  
  /**
   * __napi_schedule - schedule for receive
   * @n: entry to schedule
   *
   * The entry's receive function will be scheduled to run.
   * Consider using __napi_schedule_irqoff() if hard irqs are masked.
   */
  void __napi_schedule(struct napi_struct *n)
  {
  	unsigned long flags;
  
  	local_irq_save(flags);
  	____napi_schedule(this_cpu_ptr(&softnet_data), n);
  	local_irq_restore(flags);
  }
  EXPORT_SYMBOL(__napi_schedule);
  
  /**
   *	napi_schedule_prep - check if napi can be scheduled
   *	@n: napi context
   *
   * Test if NAPI routine is already running, and if not mark
   * it as running.  This is used as a condition variable
   * insure only one NAPI poll instance runs.  We also make
   * sure there is no pending NAPI disable.
   */
  bool napi_schedule_prep(struct napi_struct *n)
  {
  	unsigned long val, new;
  
  	do {
  		val = READ_ONCE(n->state);
  		if (unlikely(val & NAPIF_STATE_DISABLE))
  			return false;
  		new = val | NAPIF_STATE_SCHED;
  
  		/* Sets STATE_MISSED bit if STATE_SCHED was already set
  		 * This was suggested by Alexander Duyck, as compiler
  		 * emits better code than :
  		 * if (val & NAPIF_STATE_SCHED)
  		 *     new |= NAPIF_STATE_MISSED;
  		 */
  		new |= (val & NAPIF_STATE_SCHED) / NAPIF_STATE_SCHED *
  						   NAPIF_STATE_MISSED;
  	} while (cmpxchg(&n->state, val, new) != val);
  
  	return !(val & NAPIF_STATE_SCHED);
  }
  EXPORT_SYMBOL(napi_schedule_prep);
  
  /**
   * __napi_schedule_irqoff - schedule for receive
   * @n: entry to schedule
   *
   * Variant of __napi_schedule() assuming hard irqs are masked
   */
  void __napi_schedule_irqoff(struct napi_struct *n)
  {
  	____napi_schedule(this_cpu_ptr(&softnet_data), n);
  }
  EXPORT_SYMBOL(__napi_schedule_irqoff);
  
  bool napi_complete_done(struct napi_struct *n, int work_done)
  {
  	unsigned long flags, val, new;
  
  	/*
  	 * 1) Don't let napi dequeue from the cpu poll list
  	 *    just in case its running on a different cpu.
  	 * 2) If we are busy polling, do nothing here, we have
  	 *    the guarantee we will be called later.
  	 */
  	if (unlikely(n->state & (NAPIF_STATE_NPSVC |
  				 NAPIF_STATE_IN_BUSY_POLL)))
  		return false;
  
  	if (n->gro_bitmask) {
  		unsigned long timeout = 0;
  
  		if (work_done)
  			timeout = n->dev->gro_flush_timeout;
  
  		/* When the NAPI instance uses a timeout and keeps postponing
  		 * it, we need to bound somehow the time packets are kept in
  		 * the GRO layer
  		 */
  		napi_gro_flush(n, !!timeout);
  		if (timeout)
  			hrtimer_start(&n->timer, ns_to_ktime(timeout),
  				      HRTIMER_MODE_REL_PINNED);
  	}
  
  	gro_normal_list(n);
  
  	if (unlikely(!list_empty(&n->poll_list))) {
  		/* If n->poll_list is not empty, we need to mask irqs */
  		local_irq_save(flags);
  		list_del_init(&n->poll_list);
  		local_irq_restore(flags);
  	}
  
  	do {
  		val = READ_ONCE(n->state);
  
  		WARN_ON_ONCE(!(val & NAPIF_STATE_SCHED));
  
  		new = val & ~(NAPIF_STATE_MISSED | NAPIF_STATE_SCHED);
  
  		/* If STATE_MISSED was set, leave STATE_SCHED set,
  		 * because we will call napi->poll() one more time.
  		 * This C code was suggested by Alexander Duyck to help gcc.
  		 */
  		new |= (val & NAPIF_STATE_MISSED) / NAPIF_STATE_MISSED *
  						    NAPIF_STATE_SCHED;
  	} while (cmpxchg(&n->state, val, new) != val);
  
  	if (unlikely(val & NAPIF_STATE_MISSED)) {
  		__napi_schedule(n);
  		return false;
  	}
  
  	return true;
  }
  EXPORT_SYMBOL(napi_complete_done);
  
  /* must be called under rcu_read_lock(), as we dont take a reference */
  static struct napi_struct *napi_by_id(unsigned int napi_id)
  {
  	unsigned int hash = napi_id % HASH_SIZE(napi_hash);
  	struct napi_struct *napi;
  
  	hlist_for_each_entry_rcu(napi, &napi_hash[hash], napi_hash_node)
  		if (napi->napi_id == napi_id)
  			return napi;
  
  	return NULL;
  }
  
  #if defined(CONFIG_NET_RX_BUSY_POLL)
  
  #define BUSY_POLL_BUDGET 8
  
  static void busy_poll_stop(struct napi_struct *napi, void *have_poll_lock)
  {
  	int rc;
  
  	/* Busy polling means there is a high chance device driver hard irq
  	 * could not grab NAPI_STATE_SCHED, and that NAPI_STATE_MISSED was
  	 * set in napi_schedule_prep().
  	 * Since we are about to call napi->poll() once more, we can safely
  	 * clear NAPI_STATE_MISSED.
  	 *
  	 * Note: x86 could use a single "lock and ..." instruction
  	 * to perform these two clear_bit()
  	 */
  	clear_bit(NAPI_STATE_MISSED, &napi->state);
  	clear_bit(NAPI_STATE_IN_BUSY_POLL, &napi->state);
  
  	local_bh_disable();
  
  	/* All we really want here is to re-enable device interrupts.
  	 * Ideally, a new ndo_busy_poll_stop() could avoid another round.
  	 */
  	rc = napi->poll(napi, BUSY_POLL_BUDGET);
  	/* We can't gro_normal_list() here, because napi->poll() might have
  	 * rearmed the napi (napi_complete_done()) in which case it could
  	 * already be running on another CPU.
  	 */
  	trace_napi_poll(napi, rc, BUSY_POLL_BUDGET);
  	netpoll_poll_unlock(have_poll_lock);
  	if (rc == BUSY_POLL_BUDGET) {
  		/* As the whole budget was spent, we still own the napi so can
  		 * safely handle the rx_list.
  		 */
  		gro_normal_list(napi);
  		__napi_schedule(napi);
  	}
  	local_bh_enable();
  }
  
  void napi_busy_loop(unsigned int napi_id,
  		    bool (*loop_end)(void *, unsigned long),
  		    void *loop_end_arg)
  {
  	unsigned long start_time = loop_end ? busy_loop_current_time() : 0;
  	int (*napi_poll)(struct napi_struct *napi, int budget);
  	void *have_poll_lock = NULL;
  	struct napi_struct *napi;
  
  restart:
  	napi_poll = NULL;
  
  	rcu_read_lock();
  
  	napi = napi_by_id(napi_id);
  	if (!napi)
  		goto out;
  
  	preempt_disable();
  	for (;;) {
  		int work = 0;
  
  		local_bh_disable();
  		if (!napi_poll) {
  			unsigned long val = READ_ONCE(napi->state);
  
  			/* If multiple threads are competing for this napi,
  			 * we avoid dirtying napi->state as much as we can.
  			 */
  			if (val & (NAPIF_STATE_DISABLE | NAPIF_STATE_SCHED |
  				   NAPIF_STATE_IN_BUSY_POLL))
  				goto count;
  			if (cmpxchg(&napi->state, val,
  				    val | NAPIF_STATE_IN_BUSY_POLL |
  					  NAPIF_STATE_SCHED) != val)
  				goto count;
  			have_poll_lock = netpoll_poll_lock(napi);
  			napi_poll = napi->poll;
  		}
  		work = napi_poll(napi, BUSY_POLL_BUDGET);
  		trace_napi_poll(napi, work, BUSY_POLL_BUDGET);
  		gro_normal_list(napi);
  count:
  		if (work > 0)
  			__NET_ADD_STATS(dev_net(napi->dev),
  					LINUX_MIB_BUSYPOLLRXPACKETS, work);
  		local_bh_enable();
  
  		if (!loop_end || loop_end(loop_end_arg, start_time))
  			break;
  
  		if (unlikely(need_resched())) {
  			if (napi_poll)
  				busy_poll_stop(napi, have_poll_lock);
  			preempt_enable();
  			rcu_read_unlock();
  			cond_resched();
  			if (loop_end(loop_end_arg, start_time))
  				return;
  			goto restart;
  		}
  		cpu_relax();
  	}
  	if (napi_poll)
  		busy_poll_stop(napi, have_poll_lock);
  	preempt_enable();
  out:
  	rcu_read_unlock();
  }
  EXPORT_SYMBOL(napi_busy_loop);
  
  #endif /* CONFIG_NET_RX_BUSY_POLL */
  
  static void napi_hash_add(struct napi_struct *napi)
  {
  	if (test_bit(NAPI_STATE_NO_BUSY_POLL, &napi->state) ||
  	    test_and_set_bit(NAPI_STATE_HASHED, &napi->state))
  		return;
  
  	spin_lock(&napi_hash_lock);
  
  	/* 0..NR_CPUS range is reserved for sender_cpu use */
  	do {
  		if (unlikely(++napi_gen_id < MIN_NAPI_ID))
  			napi_gen_id = MIN_NAPI_ID;
  	} while (napi_by_id(napi_gen_id));
  	napi->napi_id = napi_gen_id;
  
  	hlist_add_head_rcu(&napi->napi_hash_node,
  			   &napi_hash[napi->napi_id % HASH_SIZE(napi_hash)]);
  
  	spin_unlock(&napi_hash_lock);
  }
  
  /* Warning : caller is responsible to make sure rcu grace period
   * is respected before freeing memory containing @napi
   */
  bool napi_hash_del(struct napi_struct *napi)
  {
  	bool rcu_sync_needed = false;
  
  	spin_lock(&napi_hash_lock);
  
  	if (test_and_clear_bit(NAPI_STATE_HASHED, &napi->state)) {
  		rcu_sync_needed = true;
  		hlist_del_rcu(&napi->napi_hash_node);
  	}
  	spin_unlock(&napi_hash_lock);
  	return rcu_sync_needed;
  }
  EXPORT_SYMBOL_GPL(napi_hash_del);
  
  static enum hrtimer_restart napi_watchdog(struct hrtimer *timer)
  {
  	struct napi_struct *napi;
  
  	napi = container_of(timer, struct napi_struct, timer);
  
  	/* Note : we use a relaxed variant of napi_schedule_prep() not setting
  	 * NAPI_STATE_MISSED, since we do not react to a device IRQ.
  	 */
  	if (napi->gro_bitmask && !napi_disable_pending(napi) &&
  	    !test_and_set_bit(NAPI_STATE_SCHED, &napi->state))
  		__napi_schedule_irqoff(napi);
  
  	return HRTIMER_NORESTART;
  }
  
  static void init_gro_hash(struct napi_struct *napi)
  {
  	int i;
  
  	for (i = 0; i < GRO_HASH_BUCKETS; i++) {
  		INIT_LIST_HEAD(&napi->gro_hash[i].list);
  		napi->gro_hash[i].count = 0;
  	}
  	napi->gro_bitmask = 0;
  }
  
  void netif_napi_add(struct net_device *dev, struct napi_struct *napi,
  		    int (*poll)(struct napi_struct *, int), int weight)
  {
  	INIT_LIST_HEAD(&napi->poll_list);
  	hrtimer_init(&napi->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL_PINNED);
  	napi->timer.function = napi_watchdog;
  	init_gro_hash(napi);
  	napi->skb = NULL;
  	INIT_LIST_HEAD(&napi->rx_list);
  	napi->rx_count = 0;
  	napi->poll = poll;
  	if (weight > NAPI_POLL_WEIGHT)
  		netdev_err_once(dev, "%s() called with weight %d\n", __func__,
  				weight);
  	napi->weight = weight;
  	napi->dev = dev;
  #ifdef CONFIG_NETPOLL
  	napi->poll_owner = -1;
  #endif
  	set_bit(NAPI_STATE_SCHED, &napi->state);
  	set_bit(NAPI_STATE_NPSVC, &napi->state);
  	list_add_rcu(&napi->dev_list, &dev->napi_list);
  	napi_hash_add(napi);
  }
  EXPORT_SYMBOL(netif_napi_add);
  
  void napi_disable(struct napi_struct *n)
  {
  	might_sleep();
  	set_bit(NAPI_STATE_DISABLE, &n->state);
  
  	while (test_and_set_bit(NAPI_STATE_SCHED, &n->state))
  		msleep(1);
  	while (test_and_set_bit(NAPI_STATE_NPSVC, &n->state))
  		msleep(1);
  
  	hrtimer_cancel(&n->timer);
  
  	clear_bit(NAPI_STATE_DISABLE, &n->state);
  }
  EXPORT_SYMBOL(napi_disable);
  
  static void flush_gro_hash(struct napi_struct *napi)
  {
  	int i;
  
  	for (i = 0; i < GRO_HASH_BUCKETS; i++) {
  		struct sk_buff *skb, *n;
  
  		list_for_each_entry_safe(skb, n, &napi->gro_hash[i].list, list)
  			kfree_skb(skb);
  		napi->gro_hash[i].count = 0;
  	}
  }
  
  /* Must be called in process context */
  void netif_napi_del(struct napi_struct *napi)
  {
  	might_sleep();
  	if (napi_hash_del(napi))
  		synchronize_net();
  	list_del_init(&napi->dev_list);
  	napi_free_frags(napi);
  
  	flush_gro_hash(napi);
  	napi->gro_bitmask = 0;
  }
  EXPORT_SYMBOL(netif_napi_del);
  
  static int napi_poll(struct napi_struct *n, struct list_head *repoll)
  {
  	void *have;
  	int work, weight;
  
  	list_del_init(&n->poll_list);
  
  	have = netpoll_poll_lock(n);
  
  	weight = n->weight;
  
  	/* This NAPI_STATE_SCHED test is for avoiding a race
  	 * with netpoll's poll_napi().  Only the entity which
  	 * obtains the lock and sees NAPI_STATE_SCHED set will
  	 * actually make the ->poll() call.  Therefore we avoid
  	 * accidentally calling ->poll() when NAPI is not scheduled.
  	 */
  	work = 0;
  	if (test_bit(NAPI_STATE_SCHED, &n->state)) {
  		work = n->poll(n, weight);
  		trace_napi_poll(n, work, weight);
  	}
  
  	WARN_ON_ONCE(work > weight);
  
  	if (likely(work < weight))
  		goto out_unlock;
  
  	/* Drivers must not modify the NAPI state if they
  	 * consume the entire weight.  In such cases this code
  	 * still "owns" the NAPI instance and therefore can
  	 * move the instance around on the list at-will.
  	 */
  	if (unlikely(napi_disable_pending(n))) {
  		napi_complete(n);
  		goto out_unlock;
  	}
  
  	if (n->gro_bitmask) {
  		/* flush too old packets
  		 * If HZ < 1000, flush all packets.
  		 */
  		napi_gro_flush(n, HZ >= 1000);
  	}
  
  	gro_normal_list(n);
  
  	/* Some drivers may have called napi_schedule
  	 * prior to exhausting their budget.
  	 */
  	if (unlikely(!list_empty(&n->poll_list))) {
  		pr_warn_once("%s: Budget exhausted after napi rescheduled\n",
  			     n->dev ? n->dev->name : "backlog");
  		goto out_unlock;
  	}
  
  	list_add_tail(&n->poll_list, repoll);
  
  out_unlock:
  	netpoll_poll_unlock(have);
  
  	return work;
  }
  
  static __latent_entropy void net_rx_action(struct softirq_action *h)
  {
  	struct softnet_data *sd = this_cpu_ptr(&softnet_data);
  	unsigned long time_limit = jiffies +
  		usecs_to_jiffies(netdev_budget_usecs);
  	int budget = netdev_budget;
  	LIST_HEAD(list);
  	LIST_HEAD(repoll);
  
  	local_irq_disable();
  	list_splice_init(&sd->poll_list, &list);
  	local_irq_enable();
  
  	for (;;) {
  		struct napi_struct *n;
  
  		if (list_empty(&list)) {
  			if (!sd_has_rps_ipi_waiting(sd) && list_empty(&repoll))
  				goto out;
  			break;
  		}
  
  		n = list_first_entry(&list, struct napi_struct, poll_list);
  		budget -= napi_poll(n, &repoll);
  
  		/* If softirq window is exhausted then punt.
  		 * Allow this to run for 2 jiffies since which will allow
  		 * an average latency of 1.5/HZ.
  		 */
  		if (unlikely(budget <= 0 ||
  			     time_after_eq(jiffies, time_limit))) {
  			sd->time_squeeze++;
  			break;
  		}
  	}
  
  	local_irq_disable();
  
  	list_splice_tail_init(&sd->poll_list, &list);
  	list_splice_tail(&repoll, &list);
  	list_splice(&list, &sd->poll_list);
  	if (!list_empty(&sd->poll_list))
  		__raise_softirq_irqoff(NET_RX_SOFTIRQ);
  
  	net_rps_action_and_irq_enable(sd);
  out:
  	__kfree_skb_flush();
  }
  
  struct netdev_adjacent {
  	struct net_device *dev;
  
  	/* upper master flag, there can only be one master device per list */
  	bool master;
  
  	/* lookup ignore flag */
  	bool ignore;
  
  	/* counter for the number of times this device was added to us */
  	u16 ref_nr;
  
  	/* private field for the users */
  	void *private;
  
  	struct list_head list;
  	struct rcu_head rcu;
  };
  
  static struct netdev_adjacent *__netdev_find_adj(struct net_device *adj_dev,
  						 struct list_head *adj_list)
  {
  	struct netdev_adjacent *adj;
  
  	list_for_each_entry(adj, adj_list, list) {
  		if (adj->dev == adj_dev)
  			return adj;
  	}
  	return NULL;
  }
  
  static int ____netdev_has_upper_dev(struct net_device *upper_dev, void *data)
  {
  	struct net_device *dev = data;
  
  	return upper_dev == dev;
  }
  
  /**
   * netdev_has_upper_dev - Check if device is linked to an upper device
   * @dev: device
   * @upper_dev: upper device to check
   *
   * Find out if a device is linked to specified upper device and return true
   * in case it is. Note that this checks only immediate upper device,
   * not through a complete stack of devices. The caller must hold the RTNL lock.
   */
  bool netdev_has_upper_dev(struct net_device *dev,
  			  struct net_device *upper_dev)
  {
  	ASSERT_RTNL();
  
  	return netdev_walk_all_upper_dev_rcu(dev, ____netdev_has_upper_dev,
  					     upper_dev);
  }
  EXPORT_SYMBOL(netdev_has_upper_dev);
  
  /**
   * netdev_has_upper_dev_all - Check if device is linked to an upper device
   * @dev: device
   * @upper_dev: upper device to check
   *
   * Find out if a device is linked to specified upper device and return true
   * in case it is. Note that this checks the entire upper device chain.
   * The caller must hold rcu lock.
   */
  
  bool netdev_has_upper_dev_all_rcu(struct net_device *dev,
  				  struct net_device *upper_dev)
  {
  	return !!netdev_walk_all_upper_dev_rcu(dev, ____netdev_has_upper_dev,
  					       upper_dev);
  }
  EXPORT_SYMBOL(netdev_has_upper_dev_all_rcu);
  
  /**
   * netdev_has_any_upper_dev - Check if device is linked to some device
   * @dev: device
   *
   * Find out if a device is linked to an upper device and return true in case
   * it is. The caller must hold the RTNL lock.
   */
  bool netdev_has_any_upper_dev(struct net_device *dev)
  {
  	ASSERT_RTNL();
  
  	return !list_empty(&dev->adj_list.upper);
  }
  EXPORT_SYMBOL(netdev_has_any_upper_dev);
  
  /**
   * netdev_master_upper_dev_get - Get master upper device
   * @dev: device
   *
   * Find a master upper device and return pointer to it or NULL in case
   * it's not there. The caller must hold the RTNL lock.
   */
  struct net_device *netdev_master_upper_dev_get(struct net_device *dev)
  {
  	struct netdev_adjacent *upper;
  
  	ASSERT_RTNL();
  
  	if (list_empty(&dev->adj_list.upper))
  		return NULL;
  
  	upper = list_first_entry(&dev->adj_list.upper,
  				 struct netdev_adjacent, list);
  	if (likely(upper->master))
  		return upper->dev;
  	return NULL;
  }
  EXPORT_SYMBOL(netdev_master_upper_dev_get);
  
  static struct net_device *__netdev_master_upper_dev_get(struct net_device *dev)
  {
  	struct netdev_adjacent *upper;
  
  	ASSERT_RTNL();
  
  	if (list_empty(&dev->adj_list.upper))
  		return NULL;
  
  	upper = list_first_entry(&dev->adj_list.upper,
  				 struct netdev_adjacent, list);
  	if (likely(upper->master) && !upper->ignore)
  		return upper->dev;
  	return NULL;
  }
  
  /**
   * netdev_has_any_lower_dev - Check if device is linked to some device
   * @dev: device
   *
   * Find out if a device is linked to a lower device and return true in case
   * it is. The caller must hold the RTNL lock.
   */
  static bool netdev_has_any_lower_dev(struct net_device *dev)
  {
  	ASSERT_RTNL();
  
  	return !list_empty(&dev->adj_list.lower);
  }
  
  void *netdev_adjacent_get_private(struct list_head *adj_list)
  {
  	struct netdev_adjacent *adj;
  
  	adj = list_entry(adj_list, struct netdev_adjacent, list);
  
  	return adj->private;
  }
  EXPORT_SYMBOL(netdev_adjacent_get_private);
  
  /**
   * netdev_upper_get_next_dev_rcu - Get the next dev from upper list
   * @dev: device
   * @iter: list_head ** of the current position
   *
   * Gets the next device from the dev's upper list, starting from iter
   * position. The caller must hold RCU read lock.
   */
  struct net_device *netdev_upper_get_next_dev_rcu(struct net_device *dev,
  						 struct list_head **iter)
  {
  	struct netdev_adjacent *upper;
  
  	WARN_ON_ONCE(!rcu_read_lock_held() && !lockdep_rtnl_is_held());
  
  	upper = list_entry_rcu((*iter)->next, struct netdev_adjacent, list);
  
  	if (&upper->list == &dev->adj_list.upper)
  		return NULL;
  
  	*iter = &upper->list;
  
  	return upper->dev;
  }
  EXPORT_SYMBOL(netdev_upper_get_next_dev_rcu);
  
  static struct net_device *__netdev_next_upper_dev(struct net_device *dev,
  						  struct list_head **iter,
  						  bool *ignore)
  {
  	struct netdev_adjacent *upper;
  
  	upper = list_entry((*iter)->next, struct netdev_adjacent, list);
  
  	if (&upper->list == &dev->adj_list.upper)
  		return NULL;
  
  	*iter = &upper->list;
  	*ignore = upper->ignore;
  
  	return upper->dev;
  }
  
  static struct net_device *netdev_next_upper_dev_rcu(struct net_device *dev,
  						    struct list_head **iter)
  {
  	struct netdev_adjacent *upper;
  
  	WARN_ON_ONCE(!rcu_read_lock_held() && !lockdep_rtnl_is_held());
  
  	upper = list_entry_rcu((*iter)->next, struct netdev_adjacent, list);
  
  	if (&upper->list == &dev->adj_list.upper)
  		return NULL;
  
  	*iter = &upper->list;
  
  	return upper->dev;
  }
  
  static int __netdev_walk_all_upper_dev(struct net_device *dev,
  				       int (*fn)(struct net_device *dev,
  						 void *data),
  				       void *data)
  {
  	struct net_device *udev, *next, *now, *dev_stack[MAX_NEST_DEV + 1];
  	struct list_head *niter, *iter, *iter_stack[MAX_NEST_DEV + 1];
  	int ret, cur = 0;
  	bool ignore;
  
  	now = dev;
  	iter = &dev->adj_list.upper;
  
  	while (1) {
  		if (now != dev) {
  			ret = fn(now, data);
  			if (ret)
  				return ret;
  		}
  
  		next = NULL;
  		while (1) {
  			udev = __netdev_next_upper_dev(now, &iter, &ignore);
  			if (!udev)
  				break;
  			if (ignore)
  				continue;
  
  			next = udev;
  			niter = &udev->adj_list.upper;
  			dev_stack[cur] = now;
  			iter_stack[cur++] = iter;
  			break;
  		}
  
  		if (!next) {
  			if (!cur)
  				return 0;
  			next = dev_stack[--cur];
  			niter = iter_stack[cur];
  		}
  
  		now = next;
  		iter = niter;
  	}
  
  	return 0;
  }
  
  int netdev_walk_all_upper_dev_rcu(struct net_device *dev,
  				  int (*fn)(struct net_device *dev,
  					    void *data),
  				  void *data)
  {
  	struct net_device *udev, *next, *now, *dev_stack[MAX_NEST_DEV + 1];
  	struct list_head *niter, *iter, *iter_stack[MAX_NEST_DEV + 1];
  	int ret, cur = 0;
  
  	now = dev;
  	iter = &dev->adj_list.upper;
  
  	while (1) {
  		if (now != dev) {
  			ret = fn(now, data);
  			if (ret)
  				return ret;
  		}
  
  		next = NULL;
  		while (1) {
  			udev = netdev_next_upper_dev_rcu(now, &iter);
  			if (!udev)
  				break;
  
  			next = udev;
  			niter = &udev->adj_list.upper;
  			dev_stack[cur] = now;
  			iter_stack[cur++] = iter;
  			break;
  		}
  
  		if (!next) {
  			if (!cur)
  				return 0;
  			next = dev_stack[--cur];
  			niter = iter_stack[cur];
  		}
  
  		now = next;
  		iter = niter;
  	}
  
  	return 0;
  }
  EXPORT_SYMBOL_GPL(netdev_walk_all_upper_dev_rcu);
  
  static bool __netdev_has_upper_dev(struct net_device *dev,
  				   struct net_device *upper_dev)
  {
  	ASSERT_RTNL();
  
  	return __netdev_walk_all_upper_dev(dev, ____netdev_has_upper_dev,
  					   upper_dev);
  }
  
  /**
   * netdev_lower_get_next_private - Get the next ->private from the
   *				   lower neighbour list
   * @dev: device
   * @iter: list_head ** of the current position
   *
   * Gets the next netdev_adjacent->private from the dev's lower neighbour
   * list, starting from iter position. The caller must hold either hold the
   * RTNL lock or its own locking that guarantees that the neighbour lower
   * list will remain unchanged.
   */
  void *netdev_lower_get_next_private(struct net_device *dev,
  				    struct list_head **iter)
  {
  	struct netdev_adjacent *lower;
  
  	lower = list_entry(*iter, struct netdev_adjacent, list);
  
  	if (&lower->list == &dev->adj_list.lower)
  		return NULL;
  
  	*iter = lower->list.next;
  
  	return lower->private;
  }
  EXPORT_SYMBOL(netdev_lower_get_next_private);
  
  /**
   * netdev_lower_get_next_private_rcu - Get the next ->private from the
   *				       lower neighbour list, RCU
   *				       variant
   * @dev: device
   * @iter: list_head ** of the current position
   *
   * Gets the next netdev_adjacent->private from the dev's lower neighbour
   * list, starting from iter position. The caller must hold RCU read lock.
   */
  void *netdev_lower_get_next_private_rcu(struct net_device *dev,
  					struct list_head **iter)
  {
  	struct netdev_adjacent *lower;
  
  	WARN_ON_ONCE(!rcu_read_lock_held());
  
  	lower = list_entry_rcu((*iter)->next, struct netdev_adjacent, list);
  
  	if (&lower->list == &dev->adj_list.lower)
  		return NULL;
  
  	*iter = &lower->list;
  
  	return lower->private;
  }
  EXPORT_SYMBOL(netdev_lower_get_next_private_rcu);
  
  /**
   * netdev_lower_get_next - Get the next device from the lower neighbour
   *                         list
   * @dev: device
   * @iter: list_head ** of the current position
   *
   * Gets the next netdev_adjacent from the dev's lower neighbour
   * list, starting from iter position. The caller must hold RTNL lock or
   * its own locking that guarantees that the neighbour lower
   * list will remain unchanged.
   */
  void *netdev_lower_get_next(struct net_device *dev, struct list_head **iter)
  {
  	struct netdev_adjacent *lower;
  
  	lower = list_entry(*iter, struct netdev_adjacent, list);
  
  	if (&lower->list == &dev->adj_list.lower)
  		return NULL;
  
  	*iter = lower->list.next;
  
  	return lower->dev;
  }
  EXPORT_SYMBOL(netdev_lower_get_next);
  
  static struct net_device *netdev_next_lower_dev(struct net_device *dev,
  						struct list_head **iter)
  {
  	struct netdev_adjacent *lower;
  
  	lower = list_entry((*iter)->next, struct netdev_adjacent, list);
  
  	if (&lower->list == &dev->adj_list.lower)
  		return NULL;
  
  	*iter = &lower->list;
  
  	return lower->dev;
  }
  
  static struct net_device *__netdev_next_lower_dev(struct net_device *dev,
  						  struct list_head **iter,
  						  bool *ignore)
  {
  	struct netdev_adjacent *lower;
  
  	lower = list_entry((*iter)->next, struct netdev_adjacent, list);
  
  	if (&lower->list == &dev->adj_list.lower)
  		return NULL;
  
  	*iter = &lower->list;
  	*ignore = lower->ignore;
  
  	return lower->dev;
  }
  
  int netdev_walk_all_lower_dev(struct net_device *dev,
  			      int (*fn)(struct net_device *dev,
  					void *data),
  			      void *data)
  {
  	struct net_device *ldev, *next, *now, *dev_stack[MAX_NEST_DEV + 1];
  	struct list_head *niter, *iter, *iter_stack[MAX_NEST_DEV + 1];
  	int ret, cur = 0;
  
  	now = dev;
  	iter = &dev->adj_list.lower;
  
  	while (1) {
  		if (now != dev) {
  			ret = fn(now, data);
  			if (ret)
  				return ret;
  		}
  
  		next = NULL;
  		while (1) {
  			ldev = netdev_next_lower_dev(now, &iter);
  			if (!ldev)
  				break;
  
  			next = ldev;
  			niter = &ldev->adj_list.lower;
  			dev_stack[cur] = now;
  			iter_stack[cur++] = iter;
  			break;
  		}
  
  		if (!next) {
  			if (!cur)
  				return 0;
  			next = dev_stack[--cur];
  			niter = iter_stack[cur];
  		}
  
  		now = next;
  		iter = niter;
  	}
  
  	return 0;
  }
  EXPORT_SYMBOL_GPL(netdev_walk_all_lower_dev);
  
  static int __netdev_walk_all_lower_dev(struct net_device *dev,
  				       int (*fn)(struct net_device *dev,
  						 void *data),
  				       void *data)
  {
  	struct net_device *ldev, *next, *now, *dev_stack[MAX_NEST_DEV + 1];
  	struct list_head *niter, *iter, *iter_stack[MAX_NEST_DEV + 1];
  	int ret, cur = 0;
  	bool ignore;
  
  	now = dev;
  	iter = &dev->adj_list.lower;
  
  	while (1) {
  		if (now != dev) {
  			ret = fn(now, data);
  			if (ret)
  				return ret;
  		}
  
  		next = NULL;
  		while (1) {
  			ldev = __netdev_next_lower_dev(now, &iter, &ignore);
  			if (!ldev)
  				break;
  			if (ignore)
  				continue;
  
  			next = ldev;
  			niter = &ldev->adj_list.lower;
  			dev_stack[cur] = now;
  			iter_stack[cur++] = iter;
  			break;
  		}
  
  		if (!next) {
  			if (!cur)
  				return 0;
  			next = dev_stack[--cur];
  			niter = iter_stack[cur];
  		}
  
  		now = next;
  		iter = niter;
  	}
  
  	return 0;
  }
  
  struct net_device *netdev_next_lower_dev_rcu(struct net_device *dev,
  					     struct list_head **iter)
  {
  	struct netdev_adjacent *lower;
  
  	lower = list_entry_rcu((*iter)->next, struct netdev_adjacent, list);
  	if (&lower->list == &dev->adj_list.lower)
  		return NULL;
  
  	*iter = &lower->list;
  
  	return lower->dev;
  }
  EXPORT_SYMBOL(netdev_next_lower_dev_rcu);
  
  static u8 __netdev_upper_depth(struct net_device *dev)
  {
  	struct net_device *udev;
  	struct list_head *iter;
  	u8 max_depth = 0;
  	bool ignore;
  
  	for (iter = &dev->adj_list.upper,
  	     udev = __netdev_next_upper_dev(dev, &iter, &ignore);
  	     udev;
  	     udev = __netdev_next_upper_dev(dev, &iter, &ignore)) {
  		if (ignore)
  			continue;
  		if (max_depth < udev->upper_level)
  			max_depth = udev->upper_level;
  	}
  
  	return max_depth;
  }
  
  static u8 __netdev_lower_depth(struct net_device *dev)
  {
  	struct net_device *ldev;
  	struct list_head *iter;
  	u8 max_depth = 0;
  	bool ignore;
  
  	for (iter = &dev->adj_list.lower,
  	     ldev = __netdev_next_lower_dev(dev, &iter, &ignore);
  	     ldev;
  	     ldev = __netdev_next_lower_dev(dev, &iter, &ignore)) {
  		if (ignore)
  			continue;
  		if (max_depth < ldev->lower_level)
  			max_depth = ldev->lower_level;
  	}
  
  	return max_depth;
  }
  
  static int __netdev_update_upper_level(struct net_device *dev, void *data)
  {
  	dev->upper_level = __netdev_upper_depth(dev) + 1;
  	return 0;
  }
  
  static int __netdev_update_lower_level(struct net_device *dev, void *data)
  {
  	dev->lower_level = __netdev_lower_depth(dev) + 1;
  	return 0;
  }
  
  int netdev_walk_all_lower_dev_rcu(struct net_device *dev,
  				  int (*fn)(struct net_device *dev,
  					    void *data),
  				  void *data)
  {
  	struct net_device *ldev, *next, *now, *dev_stack[MAX_NEST_DEV + 1];
  	struct list_head *niter, *iter, *iter_stack[MAX_NEST_DEV + 1];
  	int ret, cur = 0;
  
  	now = dev;
  	iter = &dev->adj_list.lower;
  
  	while (1) {
  		if (now != dev) {
  			ret = fn(now, data);
  			if (ret)
  				return ret;
  		}
  
  		next = NULL;
  		while (1) {
  			ldev = netdev_next_lower_dev_rcu(now, &iter);
  			if (!ldev)
  				break;
  
  			next = ldev;
  			niter = &ldev->adj_list.lower;
  			dev_stack[cur] = now;
  			iter_stack[cur++] = iter;
  			break;
  		}
  
  		if (!next) {
  			if (!cur)
  				return 0;
  			next = dev_stack[--cur];
  			niter = iter_stack[cur];
  		}
  
  		now = next;
  		iter = niter;
  	}
  
  	return 0;
  }
  EXPORT_SYMBOL_GPL(netdev_walk_all_lower_dev_rcu);
  
  /**
   * netdev_lower_get_first_private_rcu - Get the first ->private from the
   *				       lower neighbour list, RCU
   *				       variant
   * @dev: device
   *
   * Gets the first netdev_adjacent->private from the dev's lower neighbour
   * list. The caller must hold RCU read lock.
   */
  void *netdev_lower_get_first_private_rcu(struct net_device *dev)
  {
  	struct netdev_adjacent *lower;
  
  	lower = list_first_or_null_rcu(&dev->adj_list.lower,
  			struct netdev_adjacent, list);
  	if (lower)
  		return lower->private;
  	return NULL;
  }
  EXPORT_SYMBOL(netdev_lower_get_first_private_rcu);
  
  /**
   * netdev_master_upper_dev_get_rcu - Get master upper device
   * @dev: device
   *
   * Find a master upper device and return pointer to it or NULL in case
   * it's not there. The caller must hold the RCU read lock.
   */
  struct net_device *netdev_master_upper_dev_get_rcu(struct net_device *dev)
  {
  	struct netdev_adjacent *upper;
  
  	upper = list_first_or_null_rcu(&dev->adj_list.upper,
  				       struct netdev_adjacent, list);
  	if (upper && likely(upper->master))
  		return upper->dev;
  	return NULL;
  }
  EXPORT_SYMBOL(netdev_master_upper_dev_get_rcu);
  
  static int netdev_adjacent_sysfs_add(struct net_device *dev,
  			      struct net_device *adj_dev,
  			      struct list_head *dev_list)
  {
  	char linkname[IFNAMSIZ+7];
  
  	sprintf(linkname, dev_list == &dev->adj_list.upper ?
  		"upper_%s" : "lower_%s", adj_dev->name);
  	return sysfs_create_link(&(dev->dev.kobj), &(adj_dev->dev.kobj),
  				 linkname);
  }
  static void netdev_adjacent_sysfs_del(struct net_device *dev,
  			       char *name,
  			       struct list_head *dev_list)
  {
  	char linkname[IFNAMSIZ+7];
  
  	sprintf(linkname, dev_list == &dev->adj_list.upper ?
  		"upper_%s" : "lower_%s", name);
  	sysfs_remove_link(&(dev->dev.kobj), linkname);
  }
  
  static inline bool netdev_adjacent_is_neigh_list(struct net_device *dev,
  						 struct net_device *adj_dev,
  						 struct list_head *dev_list)
  {
  	return (dev_list == &dev->adj_list.upper ||
  		dev_list == &dev->adj_list.lower) &&
  		net_eq(dev_net(dev), dev_net(adj_dev));
  }
  
  static int __netdev_adjacent_dev_insert(struct net_device *dev,
  					struct net_device *adj_dev,
  					struct list_head *dev_list,
  					void *private, bool master)
  {
  	struct netdev_adjacent *adj;
  	int ret;
  
  	adj = __netdev_find_adj(adj_dev, dev_list);
  
  	if (adj) {
  		adj->ref_nr += 1;
  		pr_debug("Insert adjacency: dev %s adj_dev %s adj->ref_nr %d\n",
  			 dev->name, adj_dev->name, adj->ref_nr);
  
  		return 0;
  	}
  
  	adj = kmalloc(sizeof(*adj), GFP_KERNEL);
  	if (!adj)
  		return -ENOMEM;
  
  	adj->dev = adj_dev;
  	adj->master = master;
  	adj->ref_nr = 1;
  	adj->private = private;
  	adj->ignore = false;
  	dev_hold(adj_dev);
  
  	pr_debug("Insert adjacency: dev %s adj_dev %s adj->ref_nr %d; dev_hold on %s\n",
  		 dev->name, adj_dev->name, adj->ref_nr, adj_dev->name);
  
  	if (netdev_adjacent_is_neigh_list(dev, adj_dev, dev_list)) {
  		ret = netdev_adjacent_sysfs_add(dev, adj_dev, dev_list);
  		if (ret)
  			goto free_adj;
  	}
  
  	/* Ensure that master link is always the first item in list. */
  	if (master) {
  		ret = sysfs_create_link(&(dev->dev.kobj),
  					&(adj_dev->dev.kobj), "master");
  		if (ret)
  			goto remove_symlinks;
  
  		list_add_rcu(&adj->list, dev_list);
  	} else {
  		list_add_tail_rcu(&adj->list, dev_list);
  	}
  
  	return 0;
  
  remove_symlinks:
  	if (netdev_adjacent_is_neigh_list(dev, adj_dev, dev_list))
  		netdev_adjacent_sysfs_del(dev, adj_dev->name, dev_list);
  free_adj:
  	kfree(adj);
  	dev_put(adj_dev);
  
  	return ret;
  }
  
  static void __netdev_adjacent_dev_remove(struct net_device *dev,
  					 struct net_device *adj_dev,
  					 u16 ref_nr,
  					 struct list_head *dev_list)
  {
  	struct netdev_adjacent *adj;
  
  	pr_debug("Remove adjacency: dev %s adj_dev %s ref_nr %d\n",
  		 dev->name, adj_dev->name, ref_nr);
  
  	adj = __netdev_find_adj(adj_dev, dev_list);
  
  	if (!adj) {
  		pr_err("Adjacency does not exist for device %s from %s\n",
  		       dev->name, adj_dev->name);
  		WARN_ON(1);
  		return;
  	}
  
  	if (adj->ref_nr > ref_nr) {
  		pr_debug("adjacency: %s to %s ref_nr - %d = %d\n",
  			 dev->name, adj_dev->name, ref_nr,
  			 adj->ref_nr - ref_nr);
  		adj->ref_nr -= ref_nr;
  		return;
  	}
  
  	if (adj->master)
  		sysfs_remove_link(&(dev->dev.kobj), "master");
  
  	if (netdev_adjacent_is_neigh_list(dev, adj_dev, dev_list))
  		netdev_adjacent_sysfs_del(dev, adj_dev->name, dev_list);
  
  	list_del_rcu(&adj->list);
  	pr_debug("adjacency: dev_put for %s, because link removed from %s to %s\n",
  		 adj_dev->name, dev->name, adj_dev->name);
  	dev_put(adj_dev);
  	kfree_rcu(adj, rcu);
  }
  
  static int __netdev_adjacent_dev_link_lists(struct net_device *dev,
  					    struct net_device *upper_dev,
  					    struct list_head *up_list,
  					    struct list_head *down_list,
  					    void *private, bool master)
  {
  	int ret;
  
  	ret = __netdev_adjacent_dev_insert(dev, upper_dev, up_list,
  					   private, master);
  	if (ret)
  		return ret;
  
  	ret = __netdev_adjacent_dev_insert(upper_dev, dev, down_list,
  					   private, false);
  	if (ret) {
  		__netdev_adjacent_dev_remove(dev, upper_dev, 1, up_list);
  		return ret;
  	}
  
  	return 0;
  }
  
  static void __netdev_adjacent_dev_unlink_lists(struct net_device *dev,
  					       struct net_device *upper_dev,
  					       u16 ref_nr,
  					       struct list_head *up_list,
  					       struct list_head *down_list)
  {
  	__netdev_adjacent_dev_remove(dev, upper_dev, ref_nr, up_list);
  	__netdev_adjacent_dev_remove(upper_dev, dev, ref_nr, down_list);
  }
  
  static int __netdev_adjacent_dev_link_neighbour(struct net_device *dev,
  						struct net_device *upper_dev,
  						void *private, bool master)
  {
  	return __netdev_adjacent_dev_link_lists(dev, upper_dev,
  						&dev->adj_list.upper,
  						&upper_dev->adj_list.lower,
  						private, master);
  }
  
  static void __netdev_adjacent_dev_unlink_neighbour(struct net_device *dev,
  						   struct net_device *upper_dev)
  {
  	__netdev_adjacent_dev_unlink_lists(dev, upper_dev, 1,
  					   &dev->adj_list.upper,
  					   &upper_dev->adj_list.lower);
  }
  
  static int __netdev_upper_dev_link(struct net_device *dev,
  				   struct net_device *upper_dev, bool master,
  				   void *upper_priv, void *upper_info,
  				   struct netlink_ext_ack *extack)
  {
  	struct netdev_notifier_changeupper_info changeupper_info = {
  		.info = {
  			.dev = dev,
  			.extack = extack,
  		},
  		.upper_dev = upper_dev,
  		.master = master,
  		.linking = true,
  		.upper_info = upper_info,
  	};
  	struct net_device *master_dev;
  	int ret = 0;
  
  	ASSERT_RTNL();
  
  	if (dev == upper_dev)
  		return -EBUSY;
  
  	/* To prevent loops, check if dev is not upper device to upper_dev. */
  	if (__netdev_has_upper_dev(upper_dev, dev))
  		return -EBUSY;
  
  	if ((dev->lower_level + upper_dev->upper_level) > MAX_NEST_DEV)
  		return -EMLINK;
  
  	if (!master) {
  		if (__netdev_has_upper_dev(dev, upper_dev))
  			return -EEXIST;
  	} else {
  		master_dev = __netdev_master_upper_dev_get(dev);
  		if (master_dev)
  			return master_dev == upper_dev ? -EEXIST : -EBUSY;
  	}
  
  	ret = call_netdevice_notifiers_info(NETDEV_PRECHANGEUPPER,
  					    &changeupper_info.info);
  	ret = notifier_to_errno(ret);
  	if (ret)
  		return ret;
  
  	ret = __netdev_adjacent_dev_link_neighbour(dev, upper_dev, upper_priv,
  						   master);
  	if (ret)
  		return ret;
  
  	ret = call_netdevice_notifiers_info(NETDEV_CHANGEUPPER,
  					    &changeupper_info.info);
  	ret = notifier_to_errno(ret);
  	if (ret)
  		goto rollback;
  
  	__netdev_update_upper_level(dev, NULL);
  	__netdev_walk_all_lower_dev(dev, __netdev_update_upper_level, NULL);
  
  	__netdev_update_lower_level(upper_dev, NULL);
  	__netdev_walk_all_upper_dev(upper_dev, __netdev_update_lower_level,
  				    NULL);
  
  	return 0;
  
  rollback:
  	__netdev_adjacent_dev_unlink_neighbour(dev, upper_dev);
  
  	return ret;
  }
  
  /**
   * netdev_upper_dev_link - Add a link to the upper device
   * @dev: device
   * @upper_dev: new upper device
   * @extack: netlink extended ack
   *
   * Adds a link to device which is upper to this one. The caller must hold
   * the RTNL lock. On a failure a negative errno code is returned.
   * On success the reference counts are adjusted and the function
   * returns zero.
   */
  int netdev_upper_dev_link(struct net_device *dev,
  			  struct net_device *upper_dev,
  			  struct netlink_ext_ack *extack)
  {
  	return __netdev_upper_dev_link(dev, upper_dev, false,
  				       NULL, NULL, extack);
  }
  EXPORT_SYMBOL(netdev_upper_dev_link);
  
  /**
   * netdev_master_upper_dev_link - Add a master link to the upper device
   * @dev: device
   * @upper_dev: new upper device
   * @upper_priv: upper device private
   * @upper_info: upper info to be passed down via notifier
   * @extack: netlink extended ack
   *
   * Adds a link to device which is upper to this one. In this case, only
   * one master upper device can be linked, although other non-master devices
   * might be linked as well. The caller must hold the RTNL lock.
   * On a failure a negative errno code is returned. On success the reference
   * counts are adjusted and the function returns zero.
   */
  int netdev_master_upper_dev_link(struct net_device *dev,
  				 struct net_device *upper_dev,
  				 void *upper_priv, void *upper_info,
  				 struct netlink_ext_ack *extack)
  {
  	return __netdev_upper_dev_link(dev, upper_dev, true,
  				       upper_priv, upper_info, extack);
  }
  EXPORT_SYMBOL(netdev_master_upper_dev_link);
  
  /**
   * netdev_upper_dev_unlink - Removes a link to upper device
   * @dev: device
   * @upper_dev: new upper device
   *
   * Removes a link to device which is upper to this one. The caller must hold
   * the RTNL lock.
   */
  void netdev_upper_dev_unlink(struct net_device *dev,
  			     struct net_device *upper_dev)
  {
  	struct netdev_notifier_changeupper_info changeupper_info = {
  		.info = {
  			.dev = dev,
  		},
  		.upper_dev = upper_dev,
  		.linking = false,
  	};
  
  	ASSERT_RTNL();
  
  	changeupper_info.master = netdev_master_upper_dev_get(dev) == upper_dev;
  
  	call_netdevice_notifiers_info(NETDEV_PRECHANGEUPPER,
  				      &changeupper_info.info);
  
  	__netdev_adjacent_dev_unlink_neighbour(dev, upper_dev);
  
  	call_netdevice_notifiers_info(NETDEV_CHANGEUPPER,
  				      &changeupper_info.info);
  
  	__netdev_update_upper_level(dev, NULL);
  	__netdev_walk_all_lower_dev(dev, __netdev_update_upper_level, NULL);
  
  	__netdev_update_lower_level(upper_dev, NULL);
  	__netdev_walk_all_upper_dev(upper_dev, __netdev_update_lower_level,
  				    NULL);
  }
  EXPORT_SYMBOL(netdev_upper_dev_unlink);
  
  static void __netdev_adjacent_dev_set(struct net_device *upper_dev,
  				      struct net_device *lower_dev,
  				      bool val)
  {
  	struct netdev_adjacent *adj;
  
  	adj = __netdev_find_adj(lower_dev, &upper_dev->adj_list.lower);
  	if (adj)
  		adj->ignore = val;
  
  	adj = __netdev_find_adj(upper_dev, &lower_dev->adj_list.upper);
  	if (adj)
  		adj->ignore = val;
  }
  
  static void netdev_adjacent_dev_disable(struct net_device *upper_dev,
  					struct net_device *lower_dev)
  {
  	__netdev_adjacent_dev_set(upper_dev, lower_dev, true);
  }
  
  static void netdev_adjacent_dev_enable(struct net_device *upper_dev,
  				       struct net_device *lower_dev)
  {
  	__netdev_adjacent_dev_set(upper_dev, lower_dev, false);
  }
  
  int netdev_adjacent_change_prepare(struct net_device *old_dev,
  				   struct net_device *new_dev,
  				   struct net_device *dev,
  				   struct netlink_ext_ack *extack)
  {
  	int err;
  
  	if (!new_dev)
  		return 0;
  
  	if (old_dev && new_dev != old_dev)
  		netdev_adjacent_dev_disable(dev, old_dev);
  
  	err = netdev_upper_dev_link(new_dev, dev, extack);
  	if (err) {
  		if (old_dev && new_dev != old_dev)
  			netdev_adjacent_dev_enable(dev, old_dev);
  		return err;
  	}
  
  	return 0;
  }
  EXPORT_SYMBOL(netdev_adjacent_change_prepare);
  
  void netdev_adjacent_change_commit(struct net_device *old_dev,
  				   struct net_device *new_dev,
  				   struct net_device *dev)
  {
  	if (!new_dev || !old_dev)
  		return;
  
  	if (new_dev == old_dev)
  		return;
  
  	netdev_adjacent_dev_enable(dev, old_dev);
  	netdev_upper_dev_unlink(old_dev, dev);
  }
  EXPORT_SYMBOL(netdev_adjacent_change_commit);
  
  void netdev_adjacent_change_abort(struct net_device *old_dev,
  				  struct net_device *new_dev,
  				  struct net_device *dev)
  {
  	if (!new_dev)
  		return;
  
  	if (old_dev && new_dev != old_dev)
  		netdev_adjacent_dev_enable(dev, old_dev);
  
  	netdev_upper_dev_unlink(new_dev, dev);
  }
  EXPORT_SYMBOL(netdev_adjacent_change_abort);
  
  /**
   * netdev_bonding_info_change - Dispatch event about slave change
   * @dev: device
   * @bonding_info: info to dispatch
   *
   * Send NETDEV_BONDING_INFO to netdev notifiers with info.
   * The caller must hold the RTNL lock.
   */
  void netdev_bonding_info_change(struct net_device *dev,
  				struct netdev_bonding_info *bonding_info)
  {
  	struct netdev_notifier_bonding_info info = {
  		.info.dev = dev,
  	};
  
  	memcpy(&info.bonding_info, bonding_info,
  	       sizeof(struct netdev_bonding_info));
  	call_netdevice_notifiers_info(NETDEV_BONDING_INFO,
  				      &info.info);
  }
  EXPORT_SYMBOL(netdev_bonding_info_change);
  
  static void netdev_adjacent_add_links(struct net_device *dev)
  {
  	struct netdev_adjacent *iter;
  
  	struct net *net = dev_net(dev);
  
  	list_for_each_entry(iter, &dev->adj_list.upper, list) {
  		if (!net_eq(net, dev_net(iter->dev)))
  			continue;
  		netdev_adjacent_sysfs_add(iter->dev, dev,
  					  &iter->dev->adj_list.lower);
  		netdev_adjacent_sysfs_add(dev, iter->dev,
  					  &dev->adj_list.upper);
  	}
  
  	list_for_each_entry(iter, &dev->adj_list.lower, list) {
  		if (!net_eq(net, dev_net(iter->dev)))
  			continue;
  		netdev_adjacent_sysfs_add(iter->dev, dev,
  					  &iter->dev->adj_list.upper);
  		netdev_adjacent_sysfs_add(dev, iter->dev,
  					  &dev->adj_list.lower);
  	}
  }
  
  static void netdev_adjacent_del_links(struct net_device *dev)
  {
  	struct netdev_adjacent *iter;
  
  	struct net *net = dev_net(dev);
  
  	list_for_each_entry(iter, &dev->adj_list.upper, list) {
  		if (!net_eq(net, dev_net(iter->dev)))
  			continue;
  		netdev_adjacent_sysfs_del(iter->dev, dev->name,
  					  &iter->dev->adj_list.lower);
  		netdev_adjacent_sysfs_del(dev, iter->dev->name,
  					  &dev->adj_list.upper);
  	}
  
  	list_for_each_entry(iter, &dev->adj_list.lower, list) {
  		if (!net_eq(net, dev_net(iter->dev)))
  			continue;
  		netdev_adjacent_sysfs_del(iter->dev, dev->name,
  					  &iter->dev->adj_list.upper);
  		netdev_adjacent_sysfs_del(dev, iter->dev->name,
  					  &dev->adj_list.lower);
  	}
  }
  
  void netdev_adjacent_rename_links(struct net_device *dev, char *oldname)
  {
  	struct netdev_adjacent *iter;
  
  	struct net *net = dev_net(dev);
  
  	list_for_each_entry(iter, &dev->adj_list.upper, list) {
  		if (!net_eq(net, dev_net(iter->dev)))
  			continue;
  		netdev_adjacent_sysfs_del(iter->dev, oldname,
  					  &iter->dev->adj_list.lower);
  		netdev_adjacent_sysfs_add(iter->dev, dev,
  					  &iter->dev->adj_list.lower);
  	}
  
  	list_for_each_entry(iter, &dev->adj_list.lower, list) {
  		if (!net_eq(net, dev_net(iter->dev)))
  			continue;
  		netdev_adjacent_sysfs_del(iter->dev, oldname,
  					  &iter->dev->adj_list.upper);
  		netdev_adjacent_sysfs_add(iter->dev, dev,
  					  &iter->dev->adj_list.upper);
  	}
  }
  
  void *netdev_lower_dev_get_private(struct net_device *dev,
  				   struct net_device *lower_dev)
  {
  	struct netdev_adjacent *lower;
  
  	if (!lower_dev)
  		return NULL;
  	lower = __netdev_find_adj(lower_dev, &dev->adj_list.lower);
  	if (!lower)
  		return NULL;
  
  	return lower->private;
  }
  EXPORT_SYMBOL(netdev_lower_dev_get_private);
  
  
  /**
   * netdev_lower_change - Dispatch event about lower device state change
   * @lower_dev: device
   * @lower_state_info: state to dispatch
   *
   * Send NETDEV_CHANGELOWERSTATE to netdev notifiers with info.
   * The caller must hold the RTNL lock.
   */
  void netdev_lower_state_changed(struct net_device *lower_dev,
  				void *lower_state_info)
  {
  	struct netdev_notifier_changelowerstate_info changelowerstate_info = {
  		.info.dev = lower_dev,
  	};
  
  	ASSERT_RTNL();
  	changelowerstate_info.lower_state_info = lower_state_info;
  	call_netdevice_notifiers_info(NETDEV_CHANGELOWERSTATE,
  				      &changelowerstate_info.info);
  }
  EXPORT_SYMBOL(netdev_lower_state_changed);
  
  static void dev_change_rx_flags(struct net_device *dev, int flags)
  {
  	const struct net_device_ops *ops = dev->netdev_ops;
  
  	if (ops->ndo_change_rx_flags)
  		ops->ndo_change_rx_flags(dev, flags);
  }
  
  static int __dev_set_promiscuity(struct net_device *dev, int inc, bool notify)
  {
  	unsigned int old_flags = dev->flags;
  	kuid_t uid;
  	kgid_t gid;
  
  	ASSERT_RTNL();
  
  	dev->flags |= IFF_PROMISC;
  	dev->promiscuity += inc;
  	if (dev->promiscuity == 0) {
  		/*
  		 * Avoid overflow.
  		 * If inc causes overflow, untouch promisc and return error.
  		 */
  		if (inc < 0)
  			dev->flags &= ~IFF_PROMISC;
  		else {
  			dev->promiscuity -= inc;
  			pr_warn("%s: promiscuity touches roof, set promiscuity failed. promiscuity feature of device might be broken.\n",
  				dev->name);
  			return -EOVERFLOW;
  		}
  	}
  	if (dev->flags != old_flags) {
  		pr_info("device %s %s promiscuous mode\n",
  			dev->name,
  			dev->flags & IFF_PROMISC ? "entered" : "left");
  		if (audit_enabled) {
  			current_uid_gid(&uid, &gid);
  			audit_log(audit_context(), GFP_ATOMIC,
  				  AUDIT_ANOM_PROMISCUOUS,
  				  "dev=%s prom=%d old_prom=%d auid=%u uid=%u gid=%u ses=%u",
  				  dev->name, (dev->flags & IFF_PROMISC),
  				  (old_flags & IFF_PROMISC),
  				  from_kuid(&init_user_ns, audit_get_loginuid(current)),
  				  from_kuid(&init_user_ns, uid),
  				  from_kgid(&init_user_ns, gid),
  				  audit_get_sessionid(current));
  		}
  
  		dev_change_rx_flags(dev, IFF_PROMISC);
  	}
  	if (notify)
  		__dev_notify_flags(dev, old_flags, IFF_PROMISC);
  	return 0;
  }
  
  /**
   *	dev_set_promiscuity	- update promiscuity count on a device
   *	@dev: device
   *	@inc: modifier
   *
   *	Add or remove promiscuity from a device. While the count in the device
   *	remains above zero the interface remains promiscuous. Once it hits zero
   *	the device reverts back to normal filtering operation. A negative inc
   *	value is used to drop promiscuity on the device.
   *	Return 0 if successful or a negative errno code on error.
   */
  int dev_set_promiscuity(struct net_device *dev, int inc)
  {
  	unsigned int old_flags = dev->flags;
  	int err;
  
  	err = __dev_set_promiscuity(dev, inc, true);
  	if (err < 0)
  		return err;
  	if (dev->flags != old_flags)
  		dev_set_rx_mode(dev);
  	return err;
  }
  EXPORT_SYMBOL(dev_set_promiscuity);
  
  static int __dev_set_allmulti(struct net_device *dev, int inc, bool notify)
  {
  	unsigned int old_flags = dev->flags, old_gflags = dev->gflags;
  
  	ASSERT_RTNL();
  
  	dev->flags |= IFF_ALLMULTI;
  	dev->allmulti += inc;
  	if (dev->allmulti == 0) {
  		/*
  		 * Avoid overflow.
  		 * If inc causes overflow, untouch allmulti and return error.
  		 */
  		if (inc < 0)
  			dev->flags &= ~IFF_ALLMULTI;
  		else {
  			dev->allmulti -= inc;
  			pr_warn("%s: allmulti touches roof, set allmulti failed. allmulti feature of device might be broken.\n",
  				dev->name);
  			return -EOVERFLOW;
  		}
  	}
  	if (dev->flags ^ old_flags) {
  		dev_change_rx_flags(dev, IFF_ALLMULTI);
  		dev_set_rx_mode(dev);
  		if (notify)
  			__dev_notify_flags(dev, old_flags,
  					   dev->gflags ^ old_gflags);
  	}
  	return 0;
  }
  
  /**
   *	dev_set_allmulti	- update allmulti count on a device
   *	@dev: device
   *	@inc: modifier
   *
   *	Add or remove reception of all multicast frames to a device. While the
   *	count in the device remains above zero the interface remains listening
   *	to all interfaces. Once it hits zero the device reverts back to normal
   *	filtering operation. A negative @inc value is used to drop the counter
   *	when releasing a resource needing all multicasts.
   *	Return 0 if successful or a negative errno code on error.
   */
  
  int dev_set_allmulti(struct net_device *dev, int inc)
  {
  	return __dev_set_allmulti(dev, inc, true);
  }
  EXPORT_SYMBOL(dev_set_allmulti);
  
  /*
   *	Upload unicast and multicast address lists to device and
   *	configure RX filtering. When the device doesn't support unicast
   *	filtering it is put in promiscuous mode while unicast addresses
   *	are present.
   */
  void __dev_set_rx_mode(struct net_device *dev)
  {
  	const struct net_device_ops *ops = dev->netdev_ops;
  
  	/* dev_open will call this function so the list will stay sane. */
  	if (!(dev->flags&IFF_UP))
  		return;
  
  	if (!netif_device_present(dev))
  		return;
  
  	if (!(dev->priv_flags & IFF_UNICAST_FLT)) {
  		/* Unicast addresses changes may only happen under the rtnl,
  		 * therefore calling __dev_set_promiscuity here is safe.
  		 */
  		if (!netdev_uc_empty(dev) && !dev->uc_promisc) {
  			__dev_set_promiscuity(dev, 1, false);
  			dev->uc_promisc = true;
  		} else if (netdev_uc_empty(dev) && dev->uc_promisc) {
  			__dev_set_promiscuity(dev, -1, false);
  			dev->uc_promisc = false;
  		}
  	}
  
  	if (ops->ndo_set_rx_mode)
  		ops->ndo_set_rx_mode(dev);
  }
  
  void dev_set_rx_mode(struct net_device *dev)
  {
  	netif_addr_lock_bh(dev);
  	__dev_set_rx_mode(dev);
  	netif_addr_unlock_bh(dev);
  }
  
  /**
   *	dev_get_flags - get flags reported to userspace
   *	@dev: device
   *
   *	Get the combination of flag bits exported through APIs to userspace.
   */
  unsigned int dev_get_flags(const struct net_device *dev)
  {
  	unsigned int flags;
  
  	flags = (dev->flags & ~(IFF_PROMISC |
  				IFF_ALLMULTI |
  				IFF_RUNNING |
  				IFF_LOWER_UP |
  				IFF_DORMANT)) |
  		(dev->gflags & (IFF_PROMISC |
  				IFF_ALLMULTI));
  
  	if (netif_running(dev)) {
  		if (netif_oper_up(dev))
  			flags |= IFF_RUNNING;
  		if (netif_carrier_ok(dev))
  			flags |= IFF_LOWER_UP;
  		if (netif_dormant(dev))
  			flags |= IFF_DORMANT;
  	}
  
  	return flags;
  }
  EXPORT_SYMBOL(dev_get_flags);
  
  int __dev_change_flags(struct net_device *dev, unsigned int flags,
  		       struct netlink_ext_ack *extack)
  {
  	unsigned int old_flags = dev->flags;
  	int ret;
  
  	ASSERT_RTNL();
  
  	/*
  	 *	Set the flags on our device.
  	 */
  
  	dev->flags = (flags & (IFF_DEBUG | IFF_NOTRAILERS | IFF_NOARP |
  			       IFF_DYNAMIC | IFF_MULTICAST | IFF_PORTSEL |
  			       IFF_AUTOMEDIA)) |
  		     (dev->flags & (IFF_UP | IFF_VOLATILE | IFF_PROMISC |
  				    IFF_ALLMULTI));
  
  	/*
  	 *	Load in the correct multicast list now the flags have changed.
  	 */
  
  	if ((old_flags ^ flags) & IFF_MULTICAST)
  		dev_change_rx_flags(dev, IFF_MULTICAST);
  
  	dev_set_rx_mode(dev);
  
  	/*
  	 *	Have we downed the interface. We handle IFF_UP ourselves
  	 *	according to user attempts to set it, rather than blindly
  	 *	setting it.
  	 */
  
  	ret = 0;
  	if ((old_flags ^ flags) & IFF_UP) {
  		if (old_flags & IFF_UP)
  			__dev_close(dev);
  		else
  			ret = __dev_open(dev, extack);
  	}
  
  	if ((flags ^ dev->gflags) & IFF_PROMISC) {
  		int inc = (flags & IFF_PROMISC) ? 1 : -1;
  		unsigned int old_flags = dev->flags;
  
  		dev->gflags ^= IFF_PROMISC;
  
  		if (__dev_set_promiscuity(dev, inc, false) >= 0)
  			if (dev->flags != old_flags)
  				dev_set_rx_mode(dev);
  	}
  
  	/* NOTE: order of synchronization of IFF_PROMISC and IFF_ALLMULTI
  	 * is important. Some (broken) drivers set IFF_PROMISC, when
  	 * IFF_ALLMULTI is requested not asking us and not reporting.
  	 */
  	if ((flags ^ dev->gflags) & IFF_ALLMULTI) {
  		int inc = (flags & IFF_ALLMULTI) ? 1 : -1;
  
  		dev->gflags ^= IFF_ALLMULTI;
  		__dev_set_allmulti(dev, inc, false);
  	}
  
  	return ret;
  }
  
  void __dev_notify_flags(struct net_device *dev, unsigned int old_flags,
  			unsigned int gchanges)
  {
  	unsigned int changes = dev->flags ^ old_flags;
  
  	if (gchanges)
  		rtmsg_ifinfo(RTM_NEWLINK, dev, gchanges, GFP_ATOMIC);
  
  	if (changes & IFF_UP) {
  		if (dev->flags & IFF_UP)
  			call_netdevice_notifiers(NETDEV_UP, dev);
  		else
  			call_netdevice_notifiers(NETDEV_DOWN, dev);
  	}
  
  	if (dev->flags & IFF_UP &&
  	    (changes & ~(IFF_UP | IFF_PROMISC | IFF_ALLMULTI | IFF_VOLATILE))) {
  		struct netdev_notifier_change_info change_info = {
  			.info = {
  				.dev = dev,
  			},
  			.flags_changed = changes,
  		};
  
  		call_netdevice_notifiers_info(NETDEV_CHANGE, &change_info.info);
  	}
  }
  
  /**
   *	dev_change_flags - change device settings
   *	@dev: device
   *	@flags: device state flags
   *	@extack: netlink extended ack
   *
   *	Change settings on device based state flags. The flags are
   *	in the userspace exported format.
   */
  int dev_change_flags(struct net_device *dev, unsigned int flags,
  		     struct netlink_ext_ack *extack)
  {
  	int ret;
  	unsigned int changes, old_flags = dev->flags, old_gflags = dev->gflags;
  
  	ret = __dev_change_flags(dev, flags, extack);
  	if (ret < 0)
  		return ret;
  
  	changes = (old_flags ^ dev->flags) | (old_gflags ^ dev->gflags);
  	__dev_notify_flags(dev, old_flags, changes);
  	return ret;
  }
  EXPORT_SYMBOL(dev_change_flags);
  
  int __dev_set_mtu(struct net_device *dev, int new_mtu)
  {
  	const struct net_device_ops *ops = dev->netdev_ops;
  
  	if (ops->ndo_change_mtu)
  		return ops->ndo_change_mtu(dev, new_mtu);
  
  	/* Pairs with all the lockless reads of dev->mtu in the stack */
  	WRITE_ONCE(dev->mtu, new_mtu);
  	return 0;
  }
  EXPORT_SYMBOL(__dev_set_mtu);
  
  int dev_validate_mtu(struct net_device *dev, int new_mtu,
  		     struct netlink_ext_ack *extack)
  {
  	/* MTU must be positive, and in range */
  	if (new_mtu < 0 || new_mtu < dev->min_mtu) {
  		NL_SET_ERR_MSG(extack, "mtu less than device minimum");
  		return -EINVAL;
  	}
  
  	if (dev->max_mtu > 0 && new_mtu > dev->max_mtu) {
  		NL_SET_ERR_MSG(extack, "mtu greater than device maximum");
  		return -EINVAL;
  	}
  	return 0;
  }
  
  /**
   *	dev_set_mtu_ext - Change maximum transfer unit
   *	@dev: device
   *	@new_mtu: new transfer unit
   *	@extack: netlink extended ack
   *
   *	Change the maximum transfer size of the network device.
   */
  int dev_set_mtu_ext(struct net_device *dev, int new_mtu,
  		    struct netlink_ext_ack *extack)
  {
  	int err, orig_mtu;
  
  	if (new_mtu == dev->mtu)
  		return 0;
  
  	err = dev_validate_mtu(dev, new_mtu, extack);
  	if (err)
  		return err;
  
  	if (!netif_device_present(dev))
  		return -ENODEV;
  
  	err = call_netdevice_notifiers(NETDEV_PRECHANGEMTU, dev);
  	err = notifier_to_errno(err);
  	if (err)
  		return err;
  
  	orig_mtu = dev->mtu;
  	err = __dev_set_mtu(dev, new_mtu);
  
  	if (!err) {
  		err = call_netdevice_notifiers_mtu(NETDEV_CHANGEMTU, dev,
  						   orig_mtu);
  		err = notifier_to_errno(err);
  		if (err) {
  			/* setting mtu back and notifying everyone again,
  			 * so that they have a chance to revert changes.
  			 */
  			__dev_set_mtu(dev, orig_mtu);
  			call_netdevice_notifiers_mtu(NETDEV_CHANGEMTU, dev,
  						     new_mtu);
  		}
  	}
  	return err;
  }
  
  int dev_set_mtu(struct net_device *dev, int new_mtu)
  {
  	struct netlink_ext_ack extack;
  	int err;
  
  	memset(&extack, 0, sizeof(extack));
  	err = dev_set_mtu_ext(dev, new_mtu, &extack);
  	if (err && extack._msg)
  		net_err_ratelimited("%s: %s\n", dev->name, extack._msg);
  	return err;
  }
  EXPORT_SYMBOL(dev_set_mtu);
  
  /**
   *	dev_change_tx_queue_len - Change TX queue length of a netdevice
   *	@dev: device
   *	@new_len: new tx queue length
   */
  int dev_change_tx_queue_len(struct net_device *dev, unsigned long new_len)
  {
  	unsigned int orig_len = dev->tx_queue_len;
  	int res;
  
  	if (new_len != (unsigned int)new_len)
  		return -ERANGE;
  
  	if (new_len != orig_len) {
  		dev->tx_queue_len = new_len;
  		res = call_netdevice_notifiers(NETDEV_CHANGE_TX_QUEUE_LEN, dev);
  		res = notifier_to_errno(res);
  		if (res)
  			goto err_rollback;
  		res = dev_qdisc_change_tx_queue_len(dev);
  		if (res)
  			goto err_rollback;
  	}
  
  	return 0;
  
  err_rollback:
  	netdev_err(dev, "refused to change device tx_queue_len\n");
  	dev->tx_queue_len = orig_len;
  	return res;
  }
  
  /**
   *	dev_set_group - Change group this device belongs to
   *	@dev: device
   *	@new_group: group this device should belong to
   */
  void dev_set_group(struct net_device *dev, int new_group)
  {
  	dev->group = new_group;
  }
  EXPORT_SYMBOL(dev_set_group);
  
  /**
   *	dev_pre_changeaddr_notify - Call NETDEV_PRE_CHANGEADDR.
   *	@dev: device
   *	@addr: new address
   *	@extack: netlink extended ack
   */
  int dev_pre_changeaddr_notify(struct net_device *dev, const char *addr,
  			      struct netlink_ext_ack *extack)
  {
  	struct netdev_notifier_pre_changeaddr_info info = {
  		.info.dev = dev,
  		.info.extack = extack,
  		.dev_addr = addr,
  	};
  	int rc;
  
  	rc = call_netdevice_notifiers_info(NETDEV_PRE_CHANGEADDR, &info.info);
  	return notifier_to_errno(rc);
  }
  EXPORT_SYMBOL(dev_pre_changeaddr_notify);
  
  /**
   *	dev_set_mac_address - Change Media Access Control Address
   *	@dev: device
   *	@sa: new address
   *	@extack: netlink extended ack
   *
   *	Change the hardware (MAC) address of the device
   */
  int dev_set_mac_address(struct net_device *dev, struct sockaddr *sa,
  			struct netlink_ext_ack *extack)
  {
  	const struct net_device_ops *ops = dev->netdev_ops;
  	int err;
  
  	if (!ops->ndo_set_mac_address)
  		return -EOPNOTSUPP;
  	if (sa->sa_family != dev->type)
  		return -EINVAL;
  	if (!netif_device_present(dev))
  		return -ENODEV;
  	err = dev_pre_changeaddr_notify(dev, sa->sa_data, extack);
  	if (err)
  		return err;
  	err = ops->ndo_set_mac_address(dev, sa);
  	if (err)
  		return err;
  	dev->addr_assign_type = NET_ADDR_SET;
  	call_netdevice_notifiers(NETDEV_CHANGEADDR, dev);
  	add_device_randomness(dev->dev_addr, dev->addr_len);
  	return 0;
  }
  EXPORT_SYMBOL(dev_set_mac_address);
  
  /**
   *	dev_change_carrier - Change device carrier
   *	@dev: device
   *	@new_carrier: new value
   *
   *	Change device carrier
   */
  int dev_change_carrier(struct net_device *dev, bool new_carrier)
  {
  	const struct net_device_ops *ops = dev->netdev_ops;
  
  	if (!ops->ndo_change_carrier)
  		return -EOPNOTSUPP;
  	if (!netif_device_present(dev))
  		return -ENODEV;
  	return ops->ndo_change_carrier(dev, new_carrier);
  }
  EXPORT_SYMBOL(dev_change_carrier);
  
  /**
   *	dev_get_phys_port_id - Get device physical port ID
   *	@dev: device
   *	@ppid: port ID
   *
   *	Get device physical port ID
   */
  int dev_get_phys_port_id(struct net_device *dev,
  			 struct netdev_phys_item_id *ppid)
  {
  	const struct net_device_ops *ops = dev->netdev_ops;
  
  	if (!ops->ndo_get_phys_port_id)
  		return -EOPNOTSUPP;
  	return ops->ndo_get_phys_port_id(dev, ppid);
  }
  EXPORT_SYMBOL(dev_get_phys_port_id);
  
  /**
   *	dev_get_phys_port_name - Get device physical port name
   *	@dev: device
   *	@name: port name
   *	@len: limit of bytes to copy to name
   *
   *	Get device physical port name
   */
  int dev_get_phys_port_name(struct net_device *dev,
  			   char *name, size_t len)
  {
  	const struct net_device_ops *ops = dev->netdev_ops;
  	int err;
  
  	if (ops->ndo_get_phys_port_name) {
  		err = ops->ndo_get_phys_port_name(dev, name, len);
  		if (err != -EOPNOTSUPP)
  			return err;
  	}
  	return devlink_compat_phys_port_name_get(dev, name, len);
  }
  EXPORT_SYMBOL(dev_get_phys_port_name);
  
  /**
   *	dev_get_port_parent_id - Get the device's port parent identifier
   *	@dev: network device
   *	@ppid: pointer to a storage for the port's parent identifier
   *	@recurse: allow/disallow recursion to lower devices
   *
   *	Get the devices's port parent identifier
   */
  int dev_get_port_parent_id(struct net_device *dev,
  			   struct netdev_phys_item_id *ppid,
  			   bool recurse)
  {
  	const struct net_device_ops *ops = dev->netdev_ops;
  	struct netdev_phys_item_id first = { };
  	struct net_device *lower_dev;
  	struct list_head *iter;
  	int err;
  
  	if (ops->ndo_get_port_parent_id) {
  		err = ops->ndo_get_port_parent_id(dev, ppid);
  		if (err != -EOPNOTSUPP)
  			return err;
  	}
  
  	err = devlink_compat_switch_id_get(dev, ppid);
  	if (!err || err != -EOPNOTSUPP)
  		return err;
  
  	if (!recurse)
  		return -EOPNOTSUPP;
  
  	netdev_for_each_lower_dev(dev, lower_dev, iter) {
  		err = dev_get_port_parent_id(lower_dev, ppid, recurse);
  		if (err)
  			break;
  		if (!first.id_len)
  			first = *ppid;
  		else if (memcmp(&first, ppid, sizeof(*ppid)))
  			return -ENODATA;
  	}
  
  	return err;
  }
  EXPORT_SYMBOL(dev_get_port_parent_id);
  
  /**
   *	netdev_port_same_parent_id - Indicate if two network devices have
   *	the same port parent identifier
   *	@a: first network device
   *	@b: second network device
   */
  bool netdev_port_same_parent_id(struct net_device *a, struct net_device *b)
  {
  	struct netdev_phys_item_id a_id = { };
  	struct netdev_phys_item_id b_id = { };
  
  	if (dev_get_port_parent_id(a, &a_id, true) ||
  	    dev_get_port_parent_id(b, &b_id, true))
  		return false;
  
  	return netdev_phys_item_id_same(&a_id, &b_id);
  }
  EXPORT_SYMBOL(netdev_port_same_parent_id);
  
  /**
   *	dev_change_proto_down - update protocol port state information
   *	@dev: device
   *	@proto_down: new value
   *
   *	This info can be used by switch drivers to set the phys state of the
   *	port.
   */
  int dev_change_proto_down(struct net_device *dev, bool proto_down)
  {
  	const struct net_device_ops *ops = dev->netdev_ops;
  
  	if (!ops->ndo_change_proto_down)
  		return -EOPNOTSUPP;
  	if (!netif_device_present(dev))
  		return -ENODEV;
  	return ops->ndo_change_proto_down(dev, proto_down);
  }
  EXPORT_SYMBOL(dev_change_proto_down);
  
  /**
   *	dev_change_proto_down_generic - generic implementation for
   * 	ndo_change_proto_down that sets carrier according to
   * 	proto_down.
   *
   *	@dev: device
   *	@proto_down: new value
   */
  int dev_change_proto_down_generic(struct net_device *dev, bool proto_down)
  {
  	if (proto_down)
  		netif_carrier_off(dev);
  	else
  		netif_carrier_on(dev);
  	dev->proto_down = proto_down;
  	return 0;
  }
  EXPORT_SYMBOL(dev_change_proto_down_generic);
  
  u32 __dev_xdp_query(struct net_device *dev, bpf_op_t bpf_op,
  		    enum bpf_netdev_command cmd)
  {
  	struct netdev_bpf xdp;
  
  	if (!bpf_op)
  		return 0;
  
  	memset(&xdp, 0, sizeof(xdp));
  	xdp.command = cmd;
  
  	/* Query must always succeed. */
  	WARN_ON(bpf_op(dev, &xdp) < 0 && cmd == XDP_QUERY_PROG);
  
  	return xdp.prog_id;
  }
  
  static int dev_xdp_install(struct net_device *dev, bpf_op_t bpf_op,
  			   struct netlink_ext_ack *extack, u32 flags,
  			   struct bpf_prog *prog)
  {
  	struct netdev_bpf xdp;
  
  	memset(&xdp, 0, sizeof(xdp));
  	if (flags & XDP_FLAGS_HW_MODE)
  		xdp.command = XDP_SETUP_PROG_HW;
  	else
  		xdp.command = XDP_SETUP_PROG;
  	xdp.extack = extack;
  	xdp.flags = flags;
  	xdp.prog = prog;
  
  	return bpf_op(dev, &xdp);
  }
  
  static void dev_xdp_uninstall(struct net_device *dev)
  {
  	struct netdev_bpf xdp;
  	bpf_op_t ndo_bpf;
  
  	/* Remove generic XDP */
  	WARN_ON(dev_xdp_install(dev, generic_xdp_install, NULL, 0, NULL));
  
  	/* Remove from the driver */
  	ndo_bpf = dev->netdev_ops->ndo_bpf;
  	if (!ndo_bpf)
  		return;
  
  	memset(&xdp, 0, sizeof(xdp));
  	xdp.command = XDP_QUERY_PROG;
  	WARN_ON(ndo_bpf(dev, &xdp));
  	if (xdp.prog_id)
  		WARN_ON(dev_xdp_install(dev, ndo_bpf, NULL, xdp.prog_flags,
  					NULL));
  
  	/* Remove HW offload */
  	memset(&xdp, 0, sizeof(xdp));
  	xdp.command = XDP_QUERY_PROG_HW;
  	if (!ndo_bpf(dev, &xdp) && xdp.prog_id)
  		WARN_ON(dev_xdp_install(dev, ndo_bpf, NULL, xdp.prog_flags,
  					NULL));
  }
  
  /**
   *	dev_change_xdp_fd - set or clear a bpf program for a device rx path
   *	@dev: device
   *	@extack: netlink extended ack
   *	@fd: new program fd or negative value to clear
   *	@flags: xdp-related flags
   *
   *	Set or clear a bpf program for a device
   */
  int dev_change_xdp_fd(struct net_device *dev, struct netlink_ext_ack *extack,
  		      int fd, u32 flags)
  {
  	const struct net_device_ops *ops = dev->netdev_ops;
  	enum bpf_netdev_command query;
  	struct bpf_prog *prog = NULL;
  	bpf_op_t bpf_op, bpf_chk;
  	bool offload;
  	int err;
  
  	ASSERT_RTNL();
  
  	offload = flags & XDP_FLAGS_HW_MODE;
  	query = offload ? XDP_QUERY_PROG_HW : XDP_QUERY_PROG;
  
  	bpf_op = bpf_chk = ops->ndo_bpf;
  	if (!bpf_op && (flags & (XDP_FLAGS_DRV_MODE | XDP_FLAGS_HW_MODE))) {
  		NL_SET_ERR_MSG(extack, "underlying driver does not support XDP in native mode");
  		return -EOPNOTSUPP;
  	}
  	if (!bpf_op || (flags & XDP_FLAGS_SKB_MODE))
  		bpf_op = generic_xdp_install;
  	if (bpf_op == bpf_chk)
  		bpf_chk = generic_xdp_install;
  
  	if (fd >= 0) {
  		u32 prog_id;
  
  		if (!offload && __dev_xdp_query(dev, bpf_chk, XDP_QUERY_PROG)) {
  			NL_SET_ERR_MSG(extack, "native and generic XDP can't be active at the same time");
  			return -EEXIST;
  		}
  
  		prog_id = __dev_xdp_query(dev, bpf_op, query);
  		if ((flags & XDP_FLAGS_UPDATE_IF_NOEXIST) && prog_id) {
  			NL_SET_ERR_MSG(extack, "XDP program already attached");
  			return -EBUSY;
  		}
  
  		prog = bpf_prog_get_type_dev(fd, BPF_PROG_TYPE_XDP,
  					     bpf_op == ops->ndo_bpf);
  		if (IS_ERR(prog))
  			return PTR_ERR(prog);
  
  		if (!offload && bpf_prog_is_dev_bound(prog->aux)) {
  			NL_SET_ERR_MSG(extack, "using device-bound program without HW_MODE flag is not supported");
  			bpf_prog_put(prog);
  			return -EINVAL;
  		}
  
  		/* prog->aux->id may be 0 for orphaned device-bound progs */
  		if (prog->aux->id && prog->aux->id == prog_id) {
  			bpf_prog_put(prog);
  			return 0;
  		}
  	} else {
  		if (!__dev_xdp_query(dev, bpf_op, query))
  			return 0;
  	}
  
  	err = dev_xdp_install(dev, bpf_op, extack, flags, prog);
  	if (err < 0 && prog)
  		bpf_prog_put(prog);
  
  	return err;
  }
  
  /**
   *	dev_new_index	-	allocate an ifindex
   *	@net: the applicable net namespace
   *
   *	Returns a suitable unique value for a new device interface
   *	number.  The caller must hold the rtnl semaphore or the
   *	dev_base_lock to be sure it remains unique.
   */
  static int dev_new_index(struct net *net)
  {
  	int ifindex = net->ifindex;
  
  	for (;;) {
  		if (++ifindex <= 0)
  			ifindex = 1;
  		if (!__dev_get_by_index(net, ifindex))
  			return net->ifindex = ifindex;
  	}
  }
  
  /* Delayed registration/unregisteration */
  static LIST_HEAD(net_todo_list);
  DECLARE_WAIT_QUEUE_HEAD(netdev_unregistering_wq);
  
  static void net_set_todo(struct net_device *dev)
  {
  	list_add_tail(&dev->todo_list, &net_todo_list);
  	dev_net(dev)->dev_unreg_count++;
  }
  
  static void rollback_registered_many(struct list_head *head)
  {
  	struct net_device *dev, *tmp;
  	LIST_HEAD(close_head);
  
  	BUG_ON(dev_boot_phase);
  	ASSERT_RTNL();
  
  	list_for_each_entry_safe(dev, tmp, head, unreg_list) {
  		/* Some devices call without registering
  		 * for initialization unwind. Remove those
  		 * devices and proceed with the remaining.
  		 */
  		if (dev->reg_state == NETREG_UNINITIALIZED) {
  			pr_debug("unregister_netdevice: device %s/%p never was registered\n",
  				 dev->name, dev);
  
  			WARN_ON(1);
  			list_del(&dev->unreg_list);
  			continue;
  		}
  		dev->dismantle = true;
  		BUG_ON(dev->reg_state != NETREG_REGISTERED);
  	}
  
  	/* If device is running, close it first. */
  	list_for_each_entry(dev, head, unreg_list)
  		list_add_tail(&dev->close_list, &close_head);
  	dev_close_many(&close_head, true);
  
  	list_for_each_entry(dev, head, unreg_list) {
  		/* And unlink it from device chain. */
  		unlist_netdevice(dev);
  
  		dev->reg_state = NETREG_UNREGISTERING;
  	}
  	flush_all_backlogs();
  
  	synchronize_net();
  
  	list_for_each_entry(dev, head, unreg_list) {
  		struct sk_buff *skb = NULL;
  
  		/* Shutdown queueing discipline. */
  		dev_shutdown(dev);
  
  		dev_xdp_uninstall(dev);
  
  		/* Notify protocols, that we are about to destroy
  		 * this device. They should clean all the things.
  		 */
  		call_netdevice_notifiers(NETDEV_UNREGISTER, dev);
  
  		if (!dev->rtnl_link_ops ||
  		    dev->rtnl_link_state == RTNL_LINK_INITIALIZED)
  			skb = rtmsg_ifinfo_build_skb(RTM_DELLINK, dev, ~0U, 0,
  						     GFP_KERNEL, NULL, 0);
  
  		/*
  		 *	Flush the unicast and multicast chains
  		 */
  		dev_uc_flush(dev);
  		dev_mc_flush(dev);
  
  		if (dev->netdev_ops->ndo_uninit)
  			dev->netdev_ops->ndo_uninit(dev);
  
  		if (skb)
  			rtmsg_ifinfo_send(skb, dev, GFP_KERNEL);
  
  		/* Notifier chain MUST detach us all upper devices. */
  		WARN_ON(netdev_has_any_upper_dev(dev));
  		WARN_ON(netdev_has_any_lower_dev(dev));
  
  		/* Remove entries from kobject tree */
  		netdev_unregister_kobject(dev);
  #ifdef CONFIG_XPS
  		/* Remove XPS queueing entries */
  		netif_reset_xps_queues_gt(dev, 0);
  #endif
  	}
  
  	synchronize_net();
  
  	list_for_each_entry(dev, head, unreg_list)
  		dev_put(dev);
  }
  
  static void rollback_registered(struct net_device *dev)
  {
  	LIST_HEAD(single);
  
  	list_add(&dev->unreg_list, &single);
  	rollback_registered_many(&single);
  	list_del(&single);
  }
  
  static netdev_features_t netdev_sync_upper_features(struct net_device *lower,
  	struct net_device *upper, netdev_features_t features)
  {
  	netdev_features_t upper_disables = NETIF_F_UPPER_DISABLES;
  	netdev_features_t feature;
  	int feature_bit;
  
  	for_each_netdev_feature(upper_disables, feature_bit) {
  		feature = __NETIF_F_BIT(feature_bit);
  		if (!(upper->wanted_features & feature)
  		    && (features & feature)) {
  			netdev_dbg(lower, "Dropping feature %pNF, upper dev %s has it off.\n",
  				   &feature, upper->name);
  			features &= ~feature;
  		}
  	}
  
  	return features;
  }
  
  static void netdev_sync_lower_features(struct net_device *upper,
  	struct net_device *lower, netdev_features_t features)
  {
  	netdev_features_t upper_disables = NETIF_F_UPPER_DISABLES;
  	netdev_features_t feature;
  	int feature_bit;
  
  	for_each_netdev_feature(upper_disables, feature_bit) {
  		feature = __NETIF_F_BIT(feature_bit);
  		if (!(features & feature) && (lower->features & feature)) {
  			netdev_dbg(upper, "Disabling feature %pNF on lower dev %s.\n",
  				   &feature, lower->name);
  			lower->wanted_features &= ~feature;
  			__netdev_update_features(lower);
  
  			if (unlikely(lower->features & feature))
  				netdev_WARN(upper, "failed to disable %pNF on %s!\n",
  					    &feature, lower->name);
  			else
  				netdev_features_change(lower);
  		}
  	}
  }
  
  static netdev_features_t netdev_fix_features(struct net_device *dev,
  	netdev_features_t features)
  {
  	/* Fix illegal checksum combinations */
  	if ((features & NETIF_F_HW_CSUM) &&
  	    (features & (NETIF_F_IP_CSUM|NETIF_F_IPV6_CSUM))) {
  		netdev_warn(dev, "mixed HW and IP checksum settings.\n");
  		features &= ~(NETIF_F_IP_CSUM|NETIF_F_IPV6_CSUM);
  	}
  
  	/* TSO requires that SG is present as well. */
  	if ((features & NETIF_F_ALL_TSO) && !(features & NETIF_F_SG)) {
  		netdev_dbg(dev, "Dropping TSO features since no SG feature.\n");
  		features &= ~NETIF_F_ALL_TSO;
  	}
  
  	if ((features & NETIF_F_TSO) && !(features & NETIF_F_HW_CSUM) &&
  					!(features & NETIF_F_IP_CSUM)) {
  		netdev_dbg(dev, "Dropping TSO features since no CSUM feature.\n");
  		features &= ~NETIF_F_TSO;
  		features &= ~NETIF_F_TSO_ECN;
  	}
  
  	if ((features & NETIF_F_TSO6) && !(features & NETIF_F_HW_CSUM) &&
  					 !(features & NETIF_F_IPV6_CSUM)) {
  		netdev_dbg(dev, "Dropping TSO6 features since no CSUM feature.\n");
  		features &= ~NETIF_F_TSO6;
  	}
  
  	/* TSO with IPv4 ID mangling requires IPv4 TSO be enabled */
  	if ((features & NETIF_F_TSO_MANGLEID) && !(features & NETIF_F_TSO))
  		features &= ~NETIF_F_TSO_MANGLEID;
  
  	/* TSO ECN requires that TSO is present as well. */
  	if ((features & NETIF_F_ALL_TSO) == NETIF_F_TSO_ECN)
  		features &= ~NETIF_F_TSO_ECN;
  
  	/* Software GSO depends on SG. */
  	if ((features & NETIF_F_GSO) && !(features & NETIF_F_SG)) {
  		netdev_dbg(dev, "Dropping NETIF_F_GSO since no SG feature.\n");
  		features &= ~NETIF_F_GSO;
  	}
  
  	/* GSO partial features require GSO partial be set */
  	if ((features & dev->gso_partial_features) &&
  	    !(features & NETIF_F_GSO_PARTIAL)) {
  		netdev_dbg(dev,
  			   "Dropping partially supported GSO features since no GSO partial.\n");
  		features &= ~dev->gso_partial_features;
  	}
  
  	if (!(features & NETIF_F_RXCSUM)) {
  		/* NETIF_F_GRO_HW implies doing RXCSUM since every packet
  		 * successfully merged by hardware must also have the
  		 * checksum verified by hardware.  If the user does not
  		 * want to enable RXCSUM, logically, we should disable GRO_HW.
  		 */
  		if (features & NETIF_F_GRO_HW) {
  			netdev_dbg(dev, "Dropping NETIF_F_GRO_HW since no RXCSUM feature.\n");
  			features &= ~NETIF_F_GRO_HW;
  		}
  	}
  
  	/* LRO/HW-GRO features cannot be combined with RX-FCS */
  	if (features & NETIF_F_RXFCS) {
  		if (features & NETIF_F_LRO) {
  			netdev_dbg(dev, "Dropping LRO feature since RX-FCS is requested.\n");
  			features &= ~NETIF_F_LRO;
  		}
  
  		if (features & NETIF_F_GRO_HW) {
  			netdev_dbg(dev, "Dropping HW-GRO feature since RX-FCS is requested.\n");
  			features &= ~NETIF_F_GRO_HW;
  		}
  	}
  
  	return features;
  }
  
  int __netdev_update_features(struct net_device *dev)
  {
  	struct net_device *upper, *lower;
  	netdev_features_t features;
  	struct list_head *iter;
  	int err = -1;
  
  	ASSERT_RTNL();
  
  	features = netdev_get_wanted_features(dev);
  
  	if (dev->netdev_ops->ndo_fix_features)
  		features = dev->netdev_ops->ndo_fix_features(dev, features);
  
  	/* driver might be less strict about feature dependencies */
  	features = netdev_fix_features(dev, features);
  
  	/* some features can't be enabled if they're off an an upper device */
  	netdev_for_each_upper_dev_rcu(dev, upper, iter)
  		features = netdev_sync_upper_features(dev, upper, features);
  
  	if (dev->features == features)
  		goto sync_lower;
  
  	netdev_dbg(dev, "Features changed: %pNF -> %pNF\n",
  		&dev->features, &features);
  
  	if (dev->netdev_ops->ndo_set_features)
  		err = dev->netdev_ops->ndo_set_features(dev, features);
  	else
  		err = 0;
  
  	if (unlikely(err < 0)) {
  		netdev_err(dev,
  			"set_features() failed (%d); wanted %pNF, left %pNF\n",
  			err, &features, &dev->features);
  		/* return non-0 since some features might have changed and
  		 * it's better to fire a spurious notification than miss it
  		 */
  		return -1;
  	}
  
  sync_lower:
  	/* some features must be disabled on lower devices when disabled
  	 * on an upper device (think: bonding master or bridge)
  	 */
  	netdev_for_each_lower_dev(dev, lower, iter)
  		netdev_sync_lower_features(dev, lower, features);
  
  	if (!err) {
  		netdev_features_t diff = features ^ dev->features;
  
  		if (diff & NETIF_F_RX_UDP_TUNNEL_PORT) {
  			/* udp_tunnel_{get,drop}_rx_info both need
  			 * NETIF_F_RX_UDP_TUNNEL_PORT enabled on the
  			 * device, or they won't do anything.
  			 * Thus we need to update dev->features
  			 * *before* calling udp_tunnel_get_rx_info,
  			 * but *after* calling udp_tunnel_drop_rx_info.
  			 */
  			if (features & NETIF_F_RX_UDP_TUNNEL_PORT) {
  				dev->features = features;
  				udp_tunnel_get_rx_info(dev);
  			} else {
  				udp_tunnel_drop_rx_info(dev);
  			}
  		}
  
  		if (diff & NETIF_F_HW_VLAN_CTAG_FILTER) {
  			if (features & NETIF_F_HW_VLAN_CTAG_FILTER) {
  				dev->features = features;
  				err |= vlan_get_rx_ctag_filter_info(dev);
  			} else {
  				vlan_drop_rx_ctag_filter_info(dev);
  			}
  		}
  
  		if (diff & NETIF_F_HW_VLAN_STAG_FILTER) {
  			if (features & NETIF_F_HW_VLAN_STAG_FILTER) {
  				dev->features = features;
  				err |= vlan_get_rx_stag_filter_info(dev);
  			} else {
  				vlan_drop_rx_stag_filter_info(dev);
  			}
  		}
  
  		dev->features = features;
  	}
  
  	return err < 0 ? 0 : 1;
  }
  
  /**
   *	netdev_update_features - recalculate device features
   *	@dev: the device to check
   *
   *	Recalculate dev->features set and send notifications if it
   *	has changed. Should be called after driver or hardware dependent
   *	conditions might have changed that influence the features.
   */
  void netdev_update_features(struct net_device *dev)
  {
  	if (__netdev_update_features(dev))
  		netdev_features_change(dev);
  }
  EXPORT_SYMBOL(netdev_update_features);
  
  /**
   *	netdev_change_features - recalculate device features
   *	@dev: the device to check
   *
   *	Recalculate dev->features set and send notifications even
   *	if they have not changed. Should be called instead of
   *	netdev_update_features() if also dev->vlan_features might
   *	have changed to allow the changes to be propagated to stacked
   *	VLAN devices.
   */
  void netdev_change_features(struct net_device *dev)
  {
  	__netdev_update_features(dev);
  	netdev_features_change(dev);
  }
  EXPORT_SYMBOL(netdev_change_features);
  
  /**
   *	netif_stacked_transfer_operstate -	transfer operstate
   *	@rootdev: the root or lower level device to transfer state from
   *	@dev: the device to transfer operstate to
   *
   *	Transfer operational state from root to device. This is normally
   *	called when a stacking relationship exists between the root
   *	device and the device(a leaf device).
   */
  void netif_stacked_transfer_operstate(const struct net_device *rootdev,
  					struct net_device *dev)
  {
  	if (rootdev->operstate == IF_OPER_DORMANT)
  		netif_dormant_on(dev);
  	else
  		netif_dormant_off(dev);
  
  	if (netif_carrier_ok(rootdev))
  		netif_carrier_on(dev);
  	else
  		netif_carrier_off(dev);
  }
  EXPORT_SYMBOL(netif_stacked_transfer_operstate);
  
  static int netif_alloc_rx_queues(struct net_device *dev)
  {
  	unsigned int i, count = dev->num_rx_queues;
  	struct netdev_rx_queue *rx;
  	size_t sz = count * sizeof(*rx);
  	int err = 0;
  
  	BUG_ON(count < 1);
  
  	rx = kvzalloc(sz, GFP_KERNEL | __GFP_RETRY_MAYFAIL);
  	if (!rx)
  		return -ENOMEM;
  
  	dev->_rx = rx;
  
  	for (i = 0; i < count; i++) {
  		rx[i].dev = dev;
  
  		/* XDP RX-queue setup */
  		err = xdp_rxq_info_reg(&rx[i].xdp_rxq, dev, i);
  		if (err < 0)
  			goto err_rxq_info;
  	}
  	return 0;
  
  err_rxq_info:
  	/* Rollback successful reg's and free other resources */
  	while (i--)
  		xdp_rxq_info_unreg(&rx[i].xdp_rxq);
  	kvfree(dev->_rx);
  	dev->_rx = NULL;
  	return err;
  }
  
  static void netif_free_rx_queues(struct net_device *dev)
  {
  	unsigned int i, count = dev->num_rx_queues;
  
  	/* netif_alloc_rx_queues alloc failed, resources have been unreg'ed */
  	if (!dev->_rx)
  		return;
  
  	for (i = 0; i < count; i++)
  		xdp_rxq_info_unreg(&dev->_rx[i].xdp_rxq);
  
  	kvfree(dev->_rx);
  }
  
  static void netdev_init_one_queue(struct net_device *dev,
  				  struct netdev_queue *queue, void *_unused)
  {
  	/* Initialize queue lock */
  	spin_lock_init(&queue->_xmit_lock);
  	lockdep_set_class(&queue->_xmit_lock, &dev->qdisc_xmit_lock_key);
  	queue->xmit_lock_owner = -1;
  	netdev_queue_numa_node_write(queue, NUMA_NO_NODE);
  	queue->dev = dev;
  #ifdef CONFIG_BQL
  	dql_init(&queue->dql, HZ);
  #endif
  }
  
  static void netif_free_tx_queues(struct net_device *dev)
  {
  	kvfree(dev->_tx);
  }
  
  static int netif_alloc_netdev_queues(struct net_device *dev)
  {
  	unsigned int count = dev->num_tx_queues;
  	struct netdev_queue *tx;
  	size_t sz = count * sizeof(*tx);
  
  	if (count < 1 || count > 0xffff)
  		return -EINVAL;
  
  	tx = kvzalloc(sz, GFP_KERNEL | __GFP_RETRY_MAYFAIL);
  	if (!tx)
  		return -ENOMEM;
  
  	dev->_tx = tx;
  
  	netdev_for_each_tx_queue(dev, netdev_init_one_queue, NULL);
  	spin_lock_init(&dev->tx_global_lock);
  
  	return 0;
  }
  
  void netif_tx_stop_all_queues(struct net_device *dev)
  {
  	unsigned int i;
  
  	for (i = 0; i < dev->num_tx_queues; i++) {
  		struct netdev_queue *txq = netdev_get_tx_queue(dev, i);
  
  		netif_tx_stop_queue(txq);
  	}
  }
  EXPORT_SYMBOL(netif_tx_stop_all_queues);
  
  static void netdev_register_lockdep_key(struct net_device *dev)
  {
  	lockdep_register_key(&dev->qdisc_tx_busylock_key);
  	lockdep_register_key(&dev->qdisc_running_key);
  	lockdep_register_key(&dev->qdisc_xmit_lock_key);
  	lockdep_register_key(&dev->addr_list_lock_key);
  }
  
  static void netdev_unregister_lockdep_key(struct net_device *dev)
  {
  	lockdep_unregister_key(&dev->qdisc_tx_busylock_key);
  	lockdep_unregister_key(&dev->qdisc_running_key);
  	lockdep_unregister_key(&dev->qdisc_xmit_lock_key);
  	lockdep_unregister_key(&dev->addr_list_lock_key);
  }
  
  void netdev_update_lockdep_key(struct net_device *dev)
  {
  	lockdep_unregister_key(&dev->addr_list_lock_key);
  	lockdep_register_key(&dev->addr_list_lock_key);
  
  	lockdep_set_class(&dev->addr_list_lock, &dev->addr_list_lock_key);
  }
  EXPORT_SYMBOL(netdev_update_lockdep_key);
  
  /**
   *	register_netdevice	- register a network device
   *	@dev: device to register
   *
   *	Take a completed network device structure and add it to the kernel
   *	interfaces. A %NETDEV_REGISTER message is sent to the netdev notifier
   *	chain. 0 is returned on success. A negative errno code is returned
   *	on a failure to set up the device, or if the name is a duplicate.
   *
   *	Callers must hold the rtnl semaphore. You may want
   *	register_netdev() instead of this.
   *
   *	BUGS:
   *	The locking appears insufficient to guarantee two parallel registers
   *	will not get the same name.
   */
  
  int register_netdevice(struct net_device *dev)
  {
  	int ret;
  	struct net *net = dev_net(dev);
  
  	BUILD_BUG_ON(sizeof(netdev_features_t) * BITS_PER_BYTE <
  		     NETDEV_FEATURE_COUNT);
  	BUG_ON(dev_boot_phase);
  	ASSERT_RTNL();
  
  	might_sleep();
  
  	/* When net_device's are persistent, this will be fatal. */
  	BUG_ON(dev->reg_state != NETREG_UNINITIALIZED);
  	BUG_ON(!net);
  
  	spin_lock_init(&dev->addr_list_lock);
  	lockdep_set_class(&dev->addr_list_lock, &dev->addr_list_lock_key);
  
  	ret = dev_get_valid_name(net, dev, dev->name);
  	if (ret < 0)
  		goto out;
  
  	/* Init, if this function is available */
  	if (dev->netdev_ops->ndo_init) {
  		ret = dev->netdev_ops->ndo_init(dev);
  		if (ret) {
  			if (ret > 0)
  				ret = -EIO;
  			goto out;
  		}
  	}
  
  	if (((dev->hw_features | dev->features) &
  	     NETIF_F_HW_VLAN_CTAG_FILTER) &&
  	    (!dev->netdev_ops->ndo_vlan_rx_add_vid ||
  	     !dev->netdev_ops->ndo_vlan_rx_kill_vid)) {
  		netdev_WARN(dev, "Buggy VLAN acceleration in driver!\n");
  		ret = -EINVAL;
  		goto err_uninit;
  	}
  
  	ret = -EBUSY;
  	if (!dev->ifindex)
  		dev->ifindex = dev_new_index(net);
  	else if (__dev_get_by_index(net, dev->ifindex))
  		goto err_uninit;
  
  	/* Transfer changeable features to wanted_features and enable
  	 * software offloads (GSO and GRO).
  	 */
  	dev->hw_features |= NETIF_F_SOFT_FEATURES;
  	dev->features |= NETIF_F_SOFT_FEATURES;
  
  	if (dev->netdev_ops->ndo_udp_tunnel_add) {
  		dev->features |= NETIF_F_RX_UDP_TUNNEL_PORT;
  		dev->hw_features |= NETIF_F_RX_UDP_TUNNEL_PORT;
  	}
  
  	dev->wanted_features = dev->features & dev->hw_features;
  
  	if (!(dev->flags & IFF_LOOPBACK))
  		dev->hw_features |= NETIF_F_NOCACHE_COPY;
  
  	/* If IPv4 TCP segmentation offload is supported we should also
  	 * allow the device to enable segmenting the frame with the option
  	 * of ignoring a static IP ID value.  This doesn't enable the
  	 * feature itself but allows the user to enable it later.
  	 */
  	if (dev->hw_features & NETIF_F_TSO)
  		dev->hw_features |= NETIF_F_TSO_MANGLEID;
  	if (dev->vlan_features & NETIF_F_TSO)
  		dev->vlan_features |= NETIF_F_TSO_MANGLEID;
  	if (dev->mpls_features & NETIF_F_TSO)
  		dev->mpls_features |= NETIF_F_TSO_MANGLEID;
  	if (dev->hw_enc_features & NETIF_F_TSO)
  		dev->hw_enc_features |= NETIF_F_TSO_MANGLEID;
  
  	/* Make NETIF_F_HIGHDMA inheritable to VLAN devices.
  	 */
  	dev->vlan_features |= NETIF_F_HIGHDMA;
  
  	/* Make NETIF_F_SG inheritable to tunnel devices.
  	 */
  	dev->hw_enc_features |= NETIF_F_SG | NETIF_F_GSO_PARTIAL;
  
  	/* Make NETIF_F_SG inheritable to MPLS.
  	 */
  	dev->mpls_features |= NETIF_F_SG;
  
  	ret = call_netdevice_notifiers(NETDEV_POST_INIT, dev);
  	ret = notifier_to_errno(ret);
  	if (ret)
  		goto err_uninit;
  
  	ret = netdev_register_kobject(dev);
  	if (ret) {
  		dev->reg_state = NETREG_UNREGISTERED;
  		goto err_uninit;
  	}
  	dev->reg_state = NETREG_REGISTERED;
  
  	__netdev_update_features(dev);
  
  	/*
  	 *	Default initial state at registry is that the
  	 *	device is present.
  	 */
  
  	set_bit(__LINK_STATE_PRESENT, &dev->state);
  
  	linkwatch_init_dev(dev);
  
  	dev_init_scheduler(dev);
  	dev_hold(dev);
  	list_netdevice(dev);
  	add_device_randomness(dev->dev_addr, dev->addr_len);
  
  	/* If the device has permanent device address, driver should
  	 * set dev_addr and also addr_assign_type should be set to
  	 * NET_ADDR_PERM (default value).
  	 */
  	if (dev->addr_assign_type == NET_ADDR_PERM)
  		memcpy(dev->perm_addr, dev->dev_addr, dev->addr_len);
  
  	/* Notify protocols, that a new device appeared. */
  	ret = call_netdevice_notifiers(NETDEV_REGISTER, dev);
  	ret = notifier_to_errno(ret);
  	if (ret) {
  		rollback_registered(dev);
  		rcu_barrier();
  
  		dev->reg_state = NETREG_UNREGISTERED;
  		/* We should put the kobject that hold in
  		 * netdev_unregister_kobject(), otherwise
  		 * the net device cannot be freed when
  		 * driver calls free_netdev(), because the
  		 * kobject is being hold.
  		 */
  		kobject_put(&dev->dev.kobj);
  	}
  	/*
  	 *	Prevent userspace races by waiting until the network
  	 *	device is fully setup before sending notifications.
  	 */
  	if (!dev->rtnl_link_ops ||
  	    dev->rtnl_link_state == RTNL_LINK_INITIALIZED)
  		rtmsg_ifinfo(RTM_NEWLINK, dev, ~0U, GFP_KERNEL);
  
  out:
  	return ret;
  
  err_uninit:
  	if (dev->netdev_ops->ndo_uninit)
  		dev->netdev_ops->ndo_uninit(dev);
  	if (dev->priv_destructor)
  		dev->priv_destructor(dev);
  	goto out;
  }
  EXPORT_SYMBOL(register_netdevice);
  
  /**
   *	init_dummy_netdev	- init a dummy network device for NAPI
   *	@dev: device to init
   *
   *	This takes a network device structure and initialize the minimum
   *	amount of fields so it can be used to schedule NAPI polls without
   *	registering a full blown interface. This is to be used by drivers
   *	that need to tie several hardware interfaces to a single NAPI
   *	poll scheduler due to HW limitations.
   */
  int init_dummy_netdev(struct net_device *dev)
  {
  	/* Clear everything. Note we don't initialize spinlocks
  	 * are they aren't supposed to be taken by any of the
  	 * NAPI code and this dummy netdev is supposed to be
  	 * only ever used for NAPI polls
  	 */
  	memset(dev, 0, sizeof(struct net_device));
  
  	/* make sure we BUG if trying to hit standard
  	 * register/unregister code path
  	 */
  	dev->reg_state = NETREG_DUMMY;
  
  	/* NAPI wants this */
  	INIT_LIST_HEAD(&dev->napi_list);
  
  	/* a dummy interface is started by default */
  	set_bit(__LINK_STATE_PRESENT, &dev->state);
  	set_bit(__LINK_STATE_START, &dev->state);
  
  	/* napi_busy_loop stats accounting wants this */
  	dev_net_set(dev, &init_net);
  
  	/* Note : We dont allocate pcpu_refcnt for dummy devices,
  	 * because users of this 'device' dont need to change
  	 * its refcount.
  	 */
  
  	return 0;
  }
  EXPORT_SYMBOL_GPL(init_dummy_netdev);
  
  
  /**
   *	register_netdev	- register a network device
   *	@dev: device to register
   *
   *	Take a completed network device structure and add it to the kernel
   *	interfaces. A %NETDEV_REGISTER message is sent to the netdev notifier
   *	chain. 0 is returned on success. A negative errno code is returned
   *	on a failure to set up the device, or if the name is a duplicate.
   *
   *	This is a wrapper around register_netdevice that takes the rtnl semaphore
   *	and expands the device name if you passed a format string to
   *	alloc_netdev.
   */
  int register_netdev(struct net_device *dev)
  {
  	int err;
  
  	if (rtnl_lock_killable())
  		return -EINTR;
  	err = register_netdevice(dev);
  	rtnl_unlock();
  	return err;
  }
  EXPORT_SYMBOL(register_netdev);
  
  int netdev_refcnt_read(const struct net_device *dev)
  {
  	int i, refcnt = 0;
  
  	for_each_possible_cpu(i)
  		refcnt += *per_cpu_ptr(dev->pcpu_refcnt, i);
  	return refcnt;
  }
  EXPORT_SYMBOL(netdev_refcnt_read);
  
  /**
   * netdev_wait_allrefs - wait until all references are gone.
   * @dev: target net_device
   *
   * This is called when unregistering network devices.
   *
   * Any protocol or device that holds a reference should register
   * for netdevice notification, and cleanup and put back the
   * reference if they receive an UNREGISTER event.
   * We can get stuck here if buggy protocols don't correctly
   * call dev_put.
   */
  static void netdev_wait_allrefs(struct net_device *dev)
  {
  	unsigned long rebroadcast_time, warning_time;
  	int refcnt;
  
  	linkwatch_forget_dev(dev);
  
  	rebroadcast_time = warning_time = jiffies;
  	refcnt = netdev_refcnt_read(dev);
  
  	while (refcnt != 0) {
  		if (time_after(jiffies, rebroadcast_time + 1 * HZ)) {
  			rtnl_lock();
  
  			/* Rebroadcast unregister notification */
  			call_netdevice_notifiers(NETDEV_UNREGISTER, dev);
  
  			__rtnl_unlock();
  			rcu_barrier();
  			rtnl_lock();
  
  			if (test_bit(__LINK_STATE_LINKWATCH_PENDING,
  				     &dev->state)) {
  				/* We must not have linkwatch events
  				 * pending on unregister. If this
  				 * happens, we simply run the queue
  				 * unscheduled, resulting in a noop
  				 * for this device.
  				 */
  				linkwatch_run_queue();
  			}
  
  			__rtnl_unlock();
  
  			rebroadcast_time = jiffies;
  		}
  
  		msleep(250);
  
  		refcnt = netdev_refcnt_read(dev);
  
  		if (refcnt && time_after(jiffies, warning_time + 10 * HZ)) {
  			pr_emerg("unregister_netdevice: waiting for %s to become free. Usage count = %d\n",
  				 dev->name, refcnt);
  			warning_time = jiffies;
  		}
  	}
  }
  
  /* The sequence is:
   *
   *	rtnl_lock();
   *	...
   *	register_netdevice(x1);
   *	register_netdevice(x2);
   *	...
   *	unregister_netdevice(y1);
   *	unregister_netdevice(y2);
   *      ...
   *	rtnl_unlock();
   *	free_netdev(y1);
   *	free_netdev(y2);
   *
   * We are invoked by rtnl_unlock().
   * This allows us to deal with problems:
   * 1) We can delete sysfs objects which invoke hotplug
   *    without deadlocking with linkwatch via keventd.
   * 2) Since we run with the RTNL semaphore not held, we can sleep
   *    safely in order to wait for the netdev refcnt to drop to zero.
   *
   * We must not return until all unregister events added during
   * the interval the lock was held have been completed.
   */
  void netdev_run_todo(void)
  {
  	struct list_head list;
  
  	/* Snapshot list, allow later requests */
  	list_replace_init(&net_todo_list, &list);
  
  	__rtnl_unlock();
  
  
  	/* Wait for rcu callbacks to finish before next phase */
  	if (!list_empty(&list))
  		rcu_barrier();
  
  	while (!list_empty(&list)) {
  		struct net_device *dev
  			= list_first_entry(&list, struct net_device, todo_list);
  		list_del(&dev->todo_list);
  
  		if (unlikely(dev->reg_state != NETREG_UNREGISTERING)) {
  			pr_err("network todo '%s' but state %d\n",
  			       dev->name, dev->reg_state);
  			dump_stack();
  			continue;
  		}
  
  		dev->reg_state = NETREG_UNREGISTERED;
  
  		netdev_wait_allrefs(dev);
  
  		/* paranoia */
  		BUG_ON(netdev_refcnt_read(dev));
  		BUG_ON(!list_empty(&dev->ptype_all));
  		BUG_ON(!list_empty(&dev->ptype_specific));
  		WARN_ON(rcu_access_pointer(dev->ip_ptr));
  		WARN_ON(rcu_access_pointer(dev->ip6_ptr));
  #if IS_ENABLED(CONFIG_DECNET)
  		WARN_ON(dev->dn_ptr);
  #endif
  		if (dev->priv_destructor)
  			dev->priv_destructor(dev);
  		if (dev->needs_free_netdev)
  			free_netdev(dev);
  
  		/* Report a network device has been unregistered */
  		rtnl_lock();
  		dev_net(dev)->dev_unreg_count--;
  		__rtnl_unlock();
  		wake_up(&netdev_unregistering_wq);
  
  		/* Free network device */
  		kobject_put(&dev->dev.kobj);
  	}
  }
  
  /* Convert net_device_stats to rtnl_link_stats64. rtnl_link_stats64 has
   * all the same fields in the same order as net_device_stats, with only
   * the type differing, but rtnl_link_stats64 may have additional fields
   * at the end for newer counters.
   */
  void netdev_stats_to_stats64(struct rtnl_link_stats64 *stats64,
  			     const struct net_device_stats *netdev_stats)
  {
  #if BITS_PER_LONG == 64
  	BUILD_BUG_ON(sizeof(*stats64) < sizeof(*netdev_stats));
  	memcpy(stats64, netdev_stats, sizeof(*netdev_stats));
  	/* zero out counters that only exist in rtnl_link_stats64 */
  	memset((char *)stats64 + sizeof(*netdev_stats), 0,
  	       sizeof(*stats64) - sizeof(*netdev_stats));
  #else
  	size_t i, n = sizeof(*netdev_stats) / sizeof(unsigned long);
  	const unsigned long *src = (const unsigned long *)netdev_stats;
  	u64 *dst = (u64 *)stats64;
  
  	BUILD_BUG_ON(n > sizeof(*stats64) / sizeof(u64));
  	for (i = 0; i < n; i++)
  		dst[i] = src[i];
  	/* zero out counters that only exist in rtnl_link_stats64 */
  	memset((char *)stats64 + n * sizeof(u64), 0,
  	       sizeof(*stats64) - n * sizeof(u64));
  #endif
  }
  EXPORT_SYMBOL(netdev_stats_to_stats64);
  
  /**
   *	dev_get_stats	- get network device statistics
   *	@dev: device to get statistics from
   *	@storage: place to store stats
   *
   *	Get network statistics from device. Return @storage.
   *	The device driver may provide its own method by setting
   *	dev->netdev_ops->get_stats64 or dev->netdev_ops->get_stats;
   *	otherwise the internal statistics structure is used.
   */
  struct rtnl_link_stats64 *dev_get_stats(struct net_device *dev,
  					struct rtnl_link_stats64 *storage)
  {
  	const struct net_device_ops *ops = dev->netdev_ops;
  
  	if (ops->ndo_get_stats64) {
  		memset(storage, 0, sizeof(*storage));
  		ops->ndo_get_stats64(dev, storage);
  	} else if (ops->ndo_get_stats) {
  		netdev_stats_to_stats64(storage, ops->ndo_get_stats(dev));
  	} else {
  		netdev_stats_to_stats64(storage, &dev->stats);
  	}
  	storage->rx_dropped += (unsigned long)atomic_long_read(&dev->rx_dropped);
  	storage->tx_dropped += (unsigned long)atomic_long_read(&dev->tx_dropped);
  	storage->rx_nohandler += (unsigned long)atomic_long_read(&dev->rx_nohandler);
  	return storage;
  }
  EXPORT_SYMBOL(dev_get_stats);
  
  struct netdev_queue *dev_ingress_queue_create(struct net_device *dev)
  {
  	struct netdev_queue *queue = dev_ingress_queue(dev);
  
  #ifdef CONFIG_NET_CLS_ACT
  	if (queue)
  		return queue;
  	queue = kzalloc(sizeof(*queue), GFP_KERNEL);
  	if (!queue)
  		return NULL;
  	netdev_init_one_queue(dev, queue, NULL);
  	RCU_INIT_POINTER(queue->qdisc, &noop_qdisc);
  	queue->qdisc_sleeping = &noop_qdisc;
  	rcu_assign_pointer(dev->ingress_queue, queue);
  #endif
  	return queue;
  }
  
  static const struct ethtool_ops default_ethtool_ops;
  
  void netdev_set_default_ethtool_ops(struct net_device *dev,
  				    const struct ethtool_ops *ops)
  {
  	if (dev->ethtool_ops == &default_ethtool_ops)
  		dev->ethtool_ops = ops;
  }
  EXPORT_SYMBOL_GPL(netdev_set_default_ethtool_ops);
  
  void netdev_freemem(struct net_device *dev)
  {
  	char *addr = (char *)dev - dev->padded;
  
  	kvfree(addr);
  }
  
  /**
   * alloc_netdev_mqs - allocate network device
   * @sizeof_priv: size of private data to allocate space for
   * @name: device name format string
   * @name_assign_type: origin of device name
   * @setup: callback to initialize device
   * @txqs: the number of TX subqueues to allocate
   * @rxqs: the number of RX subqueues to allocate
   *
   * Allocates a struct net_device with private data area for driver use
   * and performs basic initialization.  Also allocates subqueue structs
   * for each queue on the device.
   */
  struct net_device *alloc_netdev_mqs(int sizeof_priv, const char *name,
  		unsigned char name_assign_type,
  		void (*setup)(struct net_device *),
  		unsigned int txqs, unsigned int rxqs)
  {
  	struct net_device *dev;
  	unsigned int alloc_size;
  	struct net_device *p;
  
  	BUG_ON(strlen(name) >= sizeof(dev->name));
  
  	if (txqs < 1) {
  		pr_err("alloc_netdev: Unable to allocate device with zero queues\n");
  		return NULL;
  	}
  
  	if (rxqs < 1) {
  		pr_err("alloc_netdev: Unable to allocate device with zero RX queues\n");
  		return NULL;
  	}
  
  	alloc_size = sizeof(struct net_device);
  	if (sizeof_priv) {
  		/* ensure 32-byte alignment of private area */
  		alloc_size = ALIGN(alloc_size, NETDEV_ALIGN);
  		alloc_size += sizeof_priv;
  	}
  	/* ensure 32-byte alignment of whole construct */
  	alloc_size += NETDEV_ALIGN - 1;
  
  	p = kvzalloc(alloc_size, GFP_KERNEL | __GFP_RETRY_MAYFAIL);
  	if (!p)
  		return NULL;
  
  	dev = PTR_ALIGN(p, NETDEV_ALIGN);
  	dev->padded = (char *)dev - (char *)p;
  
  	dev->pcpu_refcnt = alloc_percpu(int);
  	if (!dev->pcpu_refcnt)
  		goto free_dev;
  
  	if (dev_addr_init(dev))
  		goto free_pcpu;
  
  	dev_mc_init(dev);
  	dev_uc_init(dev);
  
  	dev_net_set(dev, &init_net);
  
  	netdev_register_lockdep_key(dev);
  
  	dev->gso_max_size = GSO_MAX_SIZE;
  	dev->gso_max_segs = GSO_MAX_SEGS;
  	dev->upper_level = 1;
  	dev->lower_level = 1;
  
  	INIT_LIST_HEAD(&dev->napi_list);
  	INIT_LIST_HEAD(&dev->unreg_list);
  	INIT_LIST_HEAD(&dev->close_list);
  	INIT_LIST_HEAD(&dev->link_watch_list);
  	INIT_LIST_HEAD(&dev->adj_list.upper);
  	INIT_LIST_HEAD(&dev->adj_list.lower);
  	INIT_LIST_HEAD(&dev->ptype_all);
  	INIT_LIST_HEAD(&dev->ptype_specific);
  #ifdef CONFIG_NET_SCHED
  	hash_init(dev->qdisc_hash);
  #endif
  	dev->priv_flags = IFF_XMIT_DST_RELEASE | IFF_XMIT_DST_RELEASE_PERM;
  	setup(dev);
  
  	if (!dev->tx_queue_len) {
  		dev->priv_flags |= IFF_NO_QUEUE;
  		dev->tx_queue_len = DEFAULT_TX_QUEUE_LEN;
  	}
  
  	dev->num_tx_queues = txqs;
  	dev->real_num_tx_queues = txqs;
  	if (netif_alloc_netdev_queues(dev))
  		goto free_all;
  
  	dev->num_rx_queues = rxqs;
  	dev->real_num_rx_queues = rxqs;
  	if (netif_alloc_rx_queues(dev))
  		goto free_all;
  
  	strcpy(dev->name, name);
  	dev->name_assign_type = name_assign_type;
  	dev->group = INIT_NETDEV_GROUP;
  	if (!dev->ethtool_ops)
  		dev->ethtool_ops = &default_ethtool_ops;
  
  	nf_hook_ingress_init(dev);
  
  	return dev;
  
  free_all:
  	free_netdev(dev);
  	return NULL;
  
  free_pcpu:
  	free_percpu(dev->pcpu_refcnt);
  free_dev:
  	netdev_freemem(dev);
  	return NULL;
  }
  EXPORT_SYMBOL(alloc_netdev_mqs);
  
  /**
   * free_netdev - free network device
   * @dev: device
   *
   * This function does the last stage of destroying an allocated device
   * interface. The reference to the device object is released. If this
   * is the last reference then it will be freed.Must be called in process
   * context.
   */
  void free_netdev(struct net_device *dev)
  {
  	struct napi_struct *p, *n;
  
  	might_sleep();
  	netif_free_tx_queues(dev);
  	netif_free_rx_queues(dev);
  
  	kfree(rcu_dereference_protected(dev->ingress_queue, 1));
  
  	/* Flush device addresses */
  	dev_addr_flush(dev);
  
  	list_for_each_entry_safe(p, n, &dev->napi_list, dev_list)
  		netif_napi_del(p);
  
  	free_percpu(dev->pcpu_refcnt);
  	dev->pcpu_refcnt = NULL;
  
  	netdev_unregister_lockdep_key(dev);
  
  	/*  Compatibility with error handling in drivers */
  	if (dev->reg_state == NETREG_UNINITIALIZED) {
  		netdev_freemem(dev);
  		return;
  	}
  
  	BUG_ON(dev->reg_state != NETREG_UNREGISTERED);
  	dev->reg_state = NETREG_RELEASED;
  
  	/* will free via device release */
  	put_device(&dev->dev);
  }
  EXPORT_SYMBOL(free_netdev);
  
  /**
   *	synchronize_net -  Synchronize with packet receive processing
   *
   *	Wait for packets currently being received to be done.
   *	Does not block later packets from starting.
   */
  void synchronize_net(void)
  {
  	might_sleep();
  	if (rtnl_is_locked())
  		synchronize_rcu_expedited();
  	else
  		synchronize_rcu();
  }
  EXPORT_SYMBOL(synchronize_net);
  
  /**
   *	unregister_netdevice_queue - remove device from the kernel
   *	@dev: device
   *	@head: list
   *
   *	This function shuts down a device interface and removes it
   *	from the kernel tables.
   *	If head not NULL, device is queued to be unregistered later.
   *
   *	Callers must hold the rtnl semaphore.  You may want
   *	unregister_netdev() instead of this.
   */
  
  void unregister_netdevice_queue(struct net_device *dev, struct list_head *head)
  {
  	ASSERT_RTNL();
  
  	if (head) {
  		list_move_tail(&dev->unreg_list, head);
  	} else {
  		rollback_registered(dev);
  		/* Finish processing unregister after unlock */
  		net_set_todo(dev);
  	}
  }
  EXPORT_SYMBOL(unregister_netdevice_queue);
  
  /**
   *	unregister_netdevice_many - unregister many devices
   *	@head: list of devices
   *
   *  Note: As most callers use a stack allocated list_head,
   *  we force a list_del() to make sure stack wont be corrupted later.
   */
  void unregister_netdevice_many(struct list_head *head)
  {
  	struct net_device *dev;
  
  	if (!list_empty(head)) {
  		rollback_registered_many(head);
  		list_for_each_entry(dev, head, unreg_list)
  			net_set_todo(dev);
  		list_del(head);
  	}
  }
  EXPORT_SYMBOL(unregister_netdevice_many);
  
  /**
   *	unregister_netdev - remove device from the kernel
   *	@dev: device
   *
   *	This function shuts down a device interface and removes it
   *	from the kernel tables.
   *
   *	This is just a wrapper for unregister_netdevice that takes
   *	the rtnl semaphore.  In general you want to use this and not
   *	unregister_netdevice.
   */
  void unregister_netdev(struct net_device *dev)
  {
  	rtnl_lock();
  	unregister_netdevice(dev);
  	rtnl_unlock();
  }
  EXPORT_SYMBOL(unregister_netdev);
  
  /**
   *	dev_change_net_namespace - move device to different nethost namespace
   *	@dev: device
   *	@net: network namespace
   *	@pat: If not NULL name pattern to try if the current device name
   *	      is already taken in the destination network namespace.
   *
   *	This function shuts down a device interface and moves it
   *	to a new network namespace. On success 0 is returned, on
   *	a failure a netagive errno code is returned.
   *
   *	Callers must hold the rtnl semaphore.
   */
  
  int dev_change_net_namespace(struct net_device *dev, struct net *net, const char *pat)
  {
  	int err, new_nsid, new_ifindex;
  
  	ASSERT_RTNL();
  
  	/* Don't allow namespace local devices to be moved. */
  	err = -EINVAL;
  	if (dev->features & NETIF_F_NETNS_LOCAL)
  		goto out;
  
  	/* Ensure the device has been registrered */
  	if (dev->reg_state != NETREG_REGISTERED)
  		goto out;
  
  	/* Get out if there is nothing todo */
  	err = 0;
  	if (net_eq(dev_net(dev), net))
  		goto out;
  
  	/* Pick the destination device name, and ensure
  	 * we can use it in the destination network namespace.
  	 */
  	err = -EEXIST;
  	if (__dev_get_by_name(net, dev->name)) {
  		/* We get here if we can't use the current device name */
  		if (!pat)
  			goto out;
  		err = dev_get_valid_name(net, dev, pat);
  		if (err < 0)
  			goto out;
  	}
  
  	/*
  	 * And now a mini version of register_netdevice unregister_netdevice.
  	 */
  
  	/* If device is running close it first. */
  	dev_close(dev);
  
  	/* And unlink it from device chain */
  	unlist_netdevice(dev);
  
  	synchronize_net();
  
  	/* Shutdown queueing discipline. */
  	dev_shutdown(dev);
  
  	/* Notify protocols, that we are about to destroy
  	 * this device. They should clean all the things.
  	 *
  	 * Note that dev->reg_state stays at NETREG_REGISTERED.
  	 * This is wanted because this way 8021q and macvlan know
  	 * the device is just moving and can keep their slaves up.
  	 */
  	call_netdevice_notifiers(NETDEV_UNREGISTER, dev);
  	rcu_barrier();
  
  	new_nsid = peernet2id_alloc(dev_net(dev), net, GFP_KERNEL);
  	/* If there is an ifindex conflict assign a new one */
  	if (__dev_get_by_index(net, dev->ifindex))
  		new_ifindex = dev_new_index(net);
  	else
  		new_ifindex = dev->ifindex;
  
  	rtmsg_ifinfo_newnet(RTM_DELLINK, dev, ~0U, GFP_KERNEL, &new_nsid,
  			    new_ifindex);
  
  	/*
  	 *	Flush the unicast and multicast chains
  	 */
  	dev_uc_flush(dev);
  	dev_mc_flush(dev);
  
  	/* Send a netdev-removed uevent to the old namespace */
  	kobject_uevent(&dev->dev.kobj, KOBJ_REMOVE);
  	netdev_adjacent_del_links(dev);
  
  	/* Actually switch the network namespace */
  	dev_net_set(dev, net);
  	dev->ifindex = new_ifindex;
  
  	/* Send a netdev-add uevent to the new namespace */
  	kobject_uevent(&dev->dev.kobj, KOBJ_ADD);
  	netdev_adjacent_add_links(dev);
  
  	/* Fixup kobjects */
  	err = device_rename(&dev->dev, dev->name);
  	WARN_ON(err);
  
  	/* Add the device back in the hashes */
  	list_netdevice(dev);
  
  	/* Notify protocols, that a new device appeared. */
  	call_netdevice_notifiers(NETDEV_REGISTER, dev);
  
  	/*
  	 *	Prevent userspace races by waiting until the network
  	 *	device is fully setup before sending notifications.
  	 */
  	rtmsg_ifinfo(RTM_NEWLINK, dev, ~0U, GFP_KERNEL);
  
  	synchronize_net();
  	err = 0;
  out:
  	return err;
  }
  EXPORT_SYMBOL_GPL(dev_change_net_namespace);
  
  static int dev_cpu_dead(unsigned int oldcpu)
  {
  	struct sk_buff **list_skb;
  	struct sk_buff *skb;
  	unsigned int cpu;
  	struct softnet_data *sd, *oldsd, *remsd = NULL;
  
  	local_irq_disable();
  	cpu = smp_processor_id();
  	sd = &per_cpu(softnet_data, cpu);
  	oldsd = &per_cpu(softnet_data, oldcpu);
  
  	/* Find end of our completion_queue. */
  	list_skb = &sd->completion_queue;
  	while (*list_skb)
  		list_skb = &(*list_skb)->next;
  	/* Append completion queue from offline CPU. */
  	*list_skb = oldsd->completion_queue;
  	oldsd->completion_queue = NULL;
  
  	/* Append output queue from offline CPU. */
  	if (oldsd->output_queue) {
  		*sd->output_queue_tailp = oldsd->output_queue;
  		sd->output_queue_tailp = oldsd->output_queue_tailp;
  		oldsd->output_queue = NULL;
  		oldsd->output_queue_tailp = &oldsd->output_queue;
  	}
  	/* Append NAPI poll list from offline CPU, with one exception :
  	 * process_backlog() must be called by cpu owning percpu backlog.
  	 * We properly handle process_queue & input_pkt_queue later.
  	 */
  	while (!list_empty(&oldsd->poll_list)) {
  		struct napi_struct *napi = list_first_entry(&oldsd->poll_list,
  							    struct napi_struct,
  							    poll_list);
  
  		list_del_init(&napi->poll_list);
  		if (napi->poll == process_backlog)
  			napi->state = 0;
  		else
  			____napi_schedule(sd, napi);
  	}
  
  	raise_softirq_irqoff(NET_TX_SOFTIRQ);
  	local_irq_enable();
  
  #ifdef CONFIG_RPS
  	remsd = oldsd->rps_ipi_list;
  	oldsd->rps_ipi_list = NULL;
  #endif
  	/* send out pending IPI's on offline CPU */
  	net_rps_send_ipi(remsd);
  
  	/* Process offline CPU's input_pkt_queue */
  	while ((skb = __skb_dequeue(&oldsd->process_queue))) {
  		netif_rx_ni(skb);
  		input_queue_head_incr(oldsd);
  	}
  	while ((skb = skb_dequeue(&oldsd->input_pkt_queue))) {
  		netif_rx_ni(skb);
  		input_queue_head_incr(oldsd);
  	}
  
  	return 0;
  }
  
  /**
   *	netdev_increment_features - increment feature set by one
   *	@all: current feature set
   *	@one: new feature set
   *	@mask: mask feature set
   *
   *	Computes a new feature set after adding a device with feature set
   *	@one to the master device with current feature set @all.  Will not
   *	enable anything that is off in @mask. Returns the new feature set.
   */
  netdev_features_t netdev_increment_features(netdev_features_t all,
  	netdev_features_t one, netdev_features_t mask)
  {
  	if (mask & NETIF_F_HW_CSUM)
  		mask |= NETIF_F_CSUM_MASK;
  	mask |= NETIF_F_VLAN_CHALLENGED;
  
  	all |= one & (NETIF_F_ONE_FOR_ALL | NETIF_F_CSUM_MASK) & mask;
  	all &= one | ~NETIF_F_ALL_FOR_ALL;
  
  	/* If one device supports hw checksumming, set for all. */
  	if (all & NETIF_F_HW_CSUM)
  		all &= ~(NETIF_F_CSUM_MASK & ~NETIF_F_HW_CSUM);
  
  	return all;
  }
  EXPORT_SYMBOL(netdev_increment_features);
  
  static struct hlist_head * __net_init netdev_create_hash(void)
  {
  	int i;
  	struct hlist_head *hash;
  
  	hash = kmalloc_array(NETDEV_HASHENTRIES, sizeof(*hash), GFP_KERNEL);
  	if (hash != NULL)
  		for (i = 0; i < NETDEV_HASHENTRIES; i++)
  			INIT_HLIST_HEAD(&hash[i]);
  
  	return hash;
  }
  
  /* Initialize per network namespace state */
  static int __net_init netdev_init(struct net *net)
  {
  	BUILD_BUG_ON(GRO_HASH_BUCKETS >
  		     8 * FIELD_SIZEOF(struct napi_struct, gro_bitmask));
  
  	if (net != &init_net)
  		INIT_LIST_HEAD(&net->dev_base_head);
  
  	net->dev_name_head = netdev_create_hash();
  	if (net->dev_name_head == NULL)
  		goto err_name;
  
  	net->dev_index_head = netdev_create_hash();
  	if (net->dev_index_head == NULL)
  		goto err_idx;
  
  	return 0;
  
  err_idx:
  	kfree(net->dev_name_head);
  err_name:
  	return -ENOMEM;
  }
  
  /**
   *	netdev_drivername - network driver for the device
   *	@dev: network device
   *
   *	Determine network driver for device.
   */
  const char *netdev_drivername(const struct net_device *dev)
  {
  	const struct device_driver *driver;
  	const struct device *parent;
  	const char *empty = "";
  
  	parent = dev->dev.parent;
  	if (!parent)
  		return empty;
  
  	driver = parent->driver;
  	if (driver && driver->name)
  		return driver->name;
  	return empty;
  }
  
  static void __netdev_printk(const char *level, const struct net_device *dev,
  			    struct va_format *vaf)
  {
  	if (dev && dev->dev.parent) {
  		dev_printk_emit(level[1] - '0',
  				dev->dev.parent,
  				"%s %s %s%s: %pV",
  				dev_driver_string(dev->dev.parent),
  				dev_name(dev->dev.parent),
  				netdev_name(dev), netdev_reg_state(dev),
  				vaf);
  	} else if (dev) {
  		printk("%s%s%s: %pV",
  		       level, netdev_name(dev), netdev_reg_state(dev), vaf);
  	} else {
  		printk("%s(NULL net_device): %pV", level, vaf);
  	}
  }
  
  void netdev_printk(const char *level, const struct net_device *dev,
  		   const char *format, ...)
  {
  	struct va_format vaf;
  	va_list args;
  
  	va_start(args, format);
  
  	vaf.fmt = format;
  	vaf.va = &args;
  
  	__netdev_printk(level, dev, &vaf);
  
  	va_end(args);
  }
  EXPORT_SYMBOL(netdev_printk);
  
  #define define_netdev_printk_level(func, level)			\
  void func(const struct net_device *dev, const char *fmt, ...)	\
  {								\
  	struct va_format vaf;					\
  	va_list args;						\
  								\
  	va_start(args, fmt);					\
  								\
  	vaf.fmt = fmt;						\
  	vaf.va = &args;						\
  								\
  	__netdev_printk(level, dev, &vaf);			\
  								\
  	va_end(args);						\
  }								\
  EXPORT_SYMBOL(func);
  
  define_netdev_printk_level(netdev_emerg, KERN_EMERG);
  define_netdev_printk_level(netdev_alert, KERN_ALERT);
  define_netdev_printk_level(netdev_crit, KERN_CRIT);
  define_netdev_printk_level(netdev_err, KERN_ERR);
  define_netdev_printk_level(netdev_warn, KERN_WARNING);
  define_netdev_printk_level(netdev_notice, KERN_NOTICE);
  define_netdev_printk_level(netdev_info, KERN_INFO);
  
  static void __net_exit netdev_exit(struct net *net)
  {
  	kfree(net->dev_name_head);
  	kfree(net->dev_index_head);
  	if (net != &init_net)
  		WARN_ON_ONCE(!list_empty(&net->dev_base_head));
  }
  
  static struct pernet_operations __net_initdata netdev_net_ops = {
  	.init = netdev_init,
  	.exit = netdev_exit,
  };
  
  static void __net_exit default_device_exit(struct net *net)
  {
  	struct net_device *dev, *aux;
  	/*
  	 * Push all migratable network devices back to the
  	 * initial network namespace
  	 */
  	rtnl_lock();
  	for_each_netdev_safe(net, dev, aux) {
  		int err;
  		char fb_name[IFNAMSIZ];
  
  		/* Ignore unmoveable devices (i.e. loopback) */
  		if (dev->features & NETIF_F_NETNS_LOCAL)
  			continue;
  
  		/* Leave virtual devices for the generic cleanup */
  		if (dev->rtnl_link_ops)
  			continue;
  
  		/* Push remaining network devices to init_net */
  		snprintf(fb_name, IFNAMSIZ, "dev%d", dev->ifindex);
  		if (__dev_get_by_name(&init_net, fb_name))
  			snprintf(fb_name, IFNAMSIZ, "dev%%d");
  		err = dev_change_net_namespace(dev, &init_net, fb_name);
  		if (err) {
  			pr_emerg("%s: failed to move %s to init_net: %d\n",
  				 __func__, dev->name, err);
  			BUG();
  		}
  	}
  	rtnl_unlock();
  }
  
  static void __net_exit rtnl_lock_unregistering(struct list_head *net_list)
  {
  	/* Return with the rtnl_lock held when there are no network
  	 * devices unregistering in any network namespace in net_list.
  	 */
  	struct net *net;
  	bool unregistering;
  	DEFINE_WAIT_FUNC(wait, woken_wake_function);
  
  	add_wait_queue(&netdev_unregistering_wq, &wait);
  	for (;;) {
  		unregistering = false;
  		rtnl_lock();
  		list_for_each_entry(net, net_list, exit_list) {
  			if (net->dev_unreg_count > 0) {
  				unregistering = true;
  				break;
  			}
  		}
  		if (!unregistering)
  			break;
  		__rtnl_unlock();
  
  		wait_woken(&wait, TASK_UNINTERRUPTIBLE, MAX_SCHEDULE_TIMEOUT);
  	}
  	remove_wait_queue(&netdev_unregistering_wq, &wait);
  }
  
  static void __net_exit default_device_exit_batch(struct list_head *net_list)
  {
  	/* At exit all network devices most be removed from a network
  	 * namespace.  Do this in the reverse order of registration.
  	 * Do this across as many network namespaces as possible to
  	 * improve batching efficiency.
  	 */
  	struct net_device *dev;
  	struct net *net;
  	LIST_HEAD(dev_kill_list);
  
  	/* To prevent network device cleanup code from dereferencing
  	 * loopback devices or network devices that have been freed
  	 * wait here for all pending unregistrations to complete,
  	 * before unregistring the loopback device and allowing the
  	 * network namespace be freed.
  	 *
  	 * The netdev todo list containing all network devices
  	 * unregistrations that happen in default_device_exit_batch
  	 * will run in the rtnl_unlock() at the end of
  	 * default_device_exit_batch.
  	 */
  	rtnl_lock_unregistering(net_list);
  	list_for_each_entry(net, net_list, exit_list) {
  		for_each_netdev_reverse(net, dev) {
  			if (dev->rtnl_link_ops && dev->rtnl_link_ops->dellink)
  				dev->rtnl_link_ops->dellink(dev, &dev_kill_list);
  			else
  				unregister_netdevice_queue(dev, &dev_kill_list);
  		}
  	}
  	unregister_netdevice_many(&dev_kill_list);
  	rtnl_unlock();
  }
  
  static struct pernet_operations __net_initdata default_device_ops = {
  	.exit = default_device_exit,
  	.exit_batch = default_device_exit_batch,
  };
  
  /*
   *	Initialize the DEV module. At boot time this walks the device list and
   *	unhooks any devices that fail to initialise (normally hardware not
   *	present) and leaves us with a valid list of present and active devices.
   *
   */
  
  /*
   *       This is called single threaded during boot, so no need
   *       to take the rtnl semaphore.
   */
  static int __init net_dev_init(void)
  {
  	int i, rc = -ENOMEM;
  
  	BUG_ON(!dev_boot_phase);
  
  	if (dev_proc_init())
  		goto out;
  
  	if (netdev_kobject_init())
  		goto out;
  
  	INIT_LIST_HEAD(&ptype_all);
  	for (i = 0; i < PTYPE_HASH_SIZE; i++)
  		INIT_LIST_HEAD(&ptype_base[i]);
  
  	INIT_LIST_HEAD(&offload_base);
  
  	if (register_pernet_subsys(&netdev_net_ops))
  		goto out;
  
  	/*
  	 *	Initialise the packet receive queues.
  	 */
  
  	for_each_possible_cpu(i) {
  		struct work_struct *flush = per_cpu_ptr(&flush_works, i);
  		struct softnet_data *sd = &per_cpu(softnet_data, i);
  
  		INIT_WORK(flush, flush_backlog);
  
  		skb_queue_head_init(&sd->input_pkt_queue);
  		skb_queue_head_init(&sd->process_queue);
  #ifdef CONFIG_XFRM_OFFLOAD
  		skb_queue_head_init(&sd->xfrm_backlog);
  #endif
  		INIT_LIST_HEAD(&sd->poll_list);
  		sd->output_queue_tailp = &sd->output_queue;
  #ifdef CONFIG_RPS
  		sd->csd.func = rps_trigger_softirq;
  		sd->csd.info = sd;
  		sd->cpu = i;
  #endif
  
  		init_gro_hash(&sd->backlog);
  		sd->backlog.poll = process_backlog;
  		sd->backlog.weight = weight_p;
  	}
  
  	dev_boot_phase = 0;
  
  	/* The loopback device is special if any other network devices
  	 * is present in a network namespace the loopback device must
  	 * be present. Since we now dynamically allocate and free the
  	 * loopback device ensure this invariant is maintained by
  	 * keeping the loopback device as the first device on the
  	 * list of network devices.  Ensuring the loopback devices
  	 * is the first device that appears and the last network device
  	 * that disappears.
  	 */
  	if (register_pernet_device(&loopback_net_ops))
  		goto out;
  
  	if (register_pernet_device(&default_device_ops))
  		goto out;
  
  	open_softirq(NET_TX_SOFTIRQ, net_tx_action);
  	open_softirq(NET_RX_SOFTIRQ, net_rx_action);
  
  	rc = cpuhp_setup_state_nocalls(CPUHP_NET_DEV_DEAD, "net/dev:dead",
  				       NULL, dev_cpu_dead);
  	WARN_ON(rc < 0);
  	rc = 0;
  out:
  	return rc;
  }
  
  subsys_initcall(net_dev_init);
  