text: /*
   * Common code for low-level network console, dump, and debugger code
   *
   * Derived from netconsole, kgdb-over-ethernet, and netdump patches
   */
  
  #ifndef _LINUX_NETPOLL_H
  #define _LINUX_NETPOLL_H
  
  #include <linux/netdevice.h>
  #include <linux/interrupt.h>
  #include <linux/rcupdate.h>
  #include <linux/list.h>
  
  struct netpoll {
  	struct net_device *dev;
  	char dev_name[IFNAMSIZ];
  	const char *name;
  	void (*rx_hook)(struct netpoll *, int, char *, int);
  
  	__be32 local_ip, remote_ip;
  	u16 local_port, remote_port;
  	u8 remote_mac[ETH_ALEN];
  
  	struct list_head rx; /* rx_np list element */
  	struct rcu_head rcu;
  };
  
  struct netpoll_info {
  	atomic_t refcnt;
  
  	int rx_flags;
  	spinlock_t rx_lock;
  	struct list_head rx_np; /* netpolls that registered an rx_hook */
  
  	struct sk_buff_head arp_tx; /* list of arp requests to reply to */
  	struct sk_buff_head txq;
  
  	struct delayed_work tx_work;
  
  	struct netpoll *netpoll;
  	struct rcu_head rcu;
  };
  
  void netpoll_send_udp(struct netpoll *np, const char *msg, int len);
  void netpoll_print_options(struct netpoll *np);
  int netpoll_parse_options(struct netpoll *np, char *opt);
  int __netpoll_setup(struct netpoll *np, struct net_device *ndev, gfp_t gfp);
  int netpoll_setup(struct netpoll *np);
  int netpoll_trap(void);
  void netpoll_set_trap(int trap);
  void __netpoll_cleanup(struct netpoll *np);
  void __netpoll_free_rcu(struct netpoll *np);
  void netpoll_cleanup(struct netpoll *np);
  int __netpoll_rx(struct sk_buff *skb, struct netpoll_info *npinfo);
  void netpoll_send_skb_on_dev(struct netpoll *np, struct sk_buff *skb,
  			     struct net_device *dev);
  static inline void netpoll_send_skb(struct netpoll *np, struct sk_buff *skb)
  {
  	unsigned long flags;
  	local_irq_save(flags);
  	netpoll_send_skb_on_dev(np, skb, np->dev);
  	local_irq_restore(flags);
  }
  
  
  
  #ifdef CONFIG_NETPOLL
  static inline bool netpoll_rx_on(struct sk_buff *skb)
  {
  	struct netpoll_info *npinfo = rcu_dereference_bh(skb->dev->npinfo);
  
  	return npinfo && (!list_empty(&npinfo->rx_np) || npinfo->rx_flags);
  }
  
  static inline bool netpoll_rx(struct sk_buff *skb)
  {
  	struct netpoll_info *npinfo;
  	unsigned long flags;
  	bool ret = false;
  
  	local_irq_save(flags);
  
  	if (!netpoll_rx_on(skb))
  		goto out;
  
  	npinfo = rcu_dereference_bh(skb->dev->npinfo);
  	spin_lock(&npinfo->rx_lock);
  	/* check rx_flags again with the lock held */
  	if (npinfo->rx_flags && __netpoll_rx(skb, npinfo))
  		ret = true;
  	spin_unlock(&npinfo->rx_lock);
  
  out:
  	local_irq_restore(flags);
  	return ret;
  }
  
  static inline int netpoll_receive_skb(struct sk_buff *skb)
  {
  	if (!list_empty(&skb->dev->napi_list))
  		return netpoll_rx(skb);
  	return 0;
  }
  
  static inline void *netpoll_poll_lock(struct napi_struct *napi)
  {
  	struct net_device *dev = napi->dev;
  
  	if (dev && dev->npinfo) {
  		spin_lock(&napi->poll_lock);
  		napi->poll_owner = smp_processor_id();
  		return napi;
  	}
  	return NULL;
  }
  
  static inline void netpoll_poll_unlock(void *have)
  {
  	struct napi_struct *napi = have;
  
  	if (napi) {
  		napi->poll_owner = -1;
  		spin_unlock(&napi->poll_lock);
  	}
  }
  
  static inline bool netpoll_tx_running(struct net_device *dev)
  {
  	return irqs_disabled();
  }
  
  #else
  static inline bool netpoll_rx(struct sk_buff *skb)
  {
  	return false;
  }
  static inline bool netpoll_rx_on(struct sk_buff *skb)
  {
  	return false;
  }
  static inline int netpoll_receive_skb(struct sk_buff *skb)
  {
  	return 0;
  }
  static inline void *netpoll_poll_lock(struct napi_struct *napi)
  {
  	return NULL;
  }
  static inline void netpoll_poll_unlock(void *have)
  {
  }
  static inline void netpoll_netdev_init(struct net_device *dev)
  {
  }
  static inline bool netpoll_tx_running(struct net_device *dev)
  {
  	return false;
  }
  #endif
  
  #endif
  