text: /* net/atm/clip.c - RFC1577 Classical IP over ATM */
  
  /* Written 1995-2000 by Werner Almesberger, EPFL LRC/ICA */
  
  #define pr_fmt(fmt) KBUILD_MODNAME ":%s: " fmt, __func__
  
  #include <linux/string.h>
  #include <linux/errno.h>
  #include <linux/kernel.h> /* for UINT_MAX */
  #include <linux/module.h>
  #include <linux/init.h>
  #include <linux/netdevice.h>
  #include <linux/skbuff.h>
  #include <linux/wait.h>
  #include <linux/timer.h>
  #include <linux/if_arp.h> /* for some manifest constants */
  #include <linux/notifier.h>
  #include <linux/atm.h>
  #include <linux/atmdev.h>
  #include <linux/atmclip.h>
  #include <linux/atmarp.h>
  #include <linux/capability.h>
  #include <linux/ip.h> /* for net/route.h */
  #include <linux/in.h> /* for struct sockaddr_in */
  #include <linux/if.h> /* for IFF_UP */
  #include <linux/inetdevice.h>
  #include <linux/bitops.h>
  #include <linux/poison.h>
  #include <linux/proc_fs.h>
  #include <linux/seq_file.h>
  #include <linux/rcupdate.h>
  #include <linux/jhash.h>
  #include <linux/slab.h>
  #include <net/route.h> /* for struct rtable and routing */
  #include <net/icmp.h> /* icmp_send */
  #include <net/arp.h>
  #include <linux/param.h> /* for HZ */
  #include <linux/uaccess.h>
  #include <asm/byteorder.h> /* for htons etc. */
  #include <linux/atomic.h>
  
  #include "common.h"
  #include "resources.h"
  #include <net/atmclip.h>
  
  static struct net_device *clip_devs;
  static struct atm_vcc *atmarpd;
  static struct timer_list idle_timer;
  static const struct neigh_ops clip_neigh_ops;
  
  static int to_atmarpd(enum atmarp_ctrl_type type, int itf, __be32 ip)
  {
  	struct sock *sk;
  	struct atmarp_ctrl *ctrl;
  	struct sk_buff *skb;
  
  	pr_debug("(%d)\n", type);
  	if (!atmarpd)
  		return -EUNATCH;
  	skb = alloc_skb(sizeof(struct atmarp_ctrl), GFP_ATOMIC);
  	if (!skb)
  		return -ENOMEM;
  	ctrl = skb_put(skb, sizeof(struct atmarp_ctrl));
  	ctrl->type = type;
  	ctrl->itf_num = itf;
  	ctrl->ip = ip;
  	atm_force_charge(atmarpd, skb->truesize);
  
  	sk = sk_atm(atmarpd);
  	skb_queue_tail(&sk->sk_receive_queue, skb);
  	sk->sk_data_ready(sk);
  	return 0;
  }
  
  static void link_vcc(struct clip_vcc *clip_vcc, struct atmarp_entry *entry)
  {
  	pr_debug("%p to entry %p (neigh %p)\n", clip_vcc, entry, entry->neigh);
  	clip_vcc->entry = entry;
  	clip_vcc->xoff = 0;	/* @@@ may overrun buffer by one packet */
  	clip_vcc->next = entry->vccs;
  	entry->vccs = clip_vcc;
  	entry->neigh->used = jiffies;
  }
  
  static void unlink_clip_vcc(struct clip_vcc *clip_vcc)
  {
  	struct atmarp_entry *entry = clip_vcc->entry;
  	struct clip_vcc **walk;
  
  	if (!entry) {
  		pr_crit("!clip_vcc->entry (clip_vcc %p)\n", clip_vcc);
  		return;
  	}
  	netif_tx_lock_bh(entry->neigh->dev);	/* block clip_start_xmit() */
  	entry->neigh->used = jiffies;
  	for (walk = &entry->vccs; *walk; walk = &(*walk)->next)
  		if (*walk == clip_vcc) {
  			int error;
  
  			*walk = clip_vcc->next;	/* atomic */
  			clip_vcc->entry = NULL;
  			if (clip_vcc->xoff)
  				netif_wake_queue(entry->neigh->dev);
  			if (entry->vccs)
  				goto out;
  			entry->expires = jiffies - 1;
  			/* force resolution or expiration */
  			error = neigh_update(entry->neigh, NULL, NUD_NONE,
  					     NEIGH_UPDATE_F_ADMIN, 0);
  			if (error)
  				pr_crit("neigh_update failed with %d\n", error);
  			goto out;
  		}
  	pr_crit("ATMARP: failed (entry %p, vcc 0x%p)\n", entry, clip_vcc);
  out:
  	netif_tx_unlock_bh(entry->neigh->dev);
  }
  
  /* The neighbour entry n->lock is held. */
  static int neigh_check_cb(struct neighbour *n)
  {
  	struct atmarp_entry *entry = neighbour_priv(n);
  	struct clip_vcc *cv;
  
  	if (n->ops != &clip_neigh_ops)
  		return 0;
  	for (cv = entry->vccs; cv; cv = cv->next) {
  		unsigned long exp = cv->last_use + cv->idle_timeout;
  
  		if (cv->idle_timeout && time_after(jiffies, exp)) {
  			pr_debug("releasing vcc %p->%p of entry %p\n",
  				 cv, cv->vcc, entry);
  			vcc_release_async(cv->vcc, -ETIMEDOUT);
  		}
  	}
  
  	if (entry->vccs || time_before(jiffies, entry->expires))
  		return 0;
  
  	if (refcount_read(&n->refcnt) > 1) {
  		struct sk_buff *skb;
  
  		pr_debug("destruction postponed with ref %d\n",
  			 refcount_read(&n->refcnt));
  
  		while ((skb = skb_dequeue(&n->arp_queue)) != NULL)
  			dev_kfree_skb(skb);
  
  		return 0;
  	}
  
  	pr_debug("expired neigh %p\n", n);
  	return 1;
  }
  
  static void idle_timer_check(struct timer_list *unused)
  {
  	write_lock(&arp_tbl.lock);
  	__neigh_for_each_release(&arp_tbl, neigh_check_cb);
  	mod_timer(&idle_timer, jiffies + CLIP_CHECK_INTERVAL * HZ);
  	write_unlock(&arp_tbl.lock);
  }
  
  static int clip_arp_rcv(struct sk_buff *skb)
  {
  	struct atm_vcc *vcc;
  
  	pr_debug("\n");
  	vcc = ATM_SKB(skb)->vcc;
  	if (!vcc || !atm_charge(vcc, skb->truesize)) {
  		dev_kfree_skb_any(skb);
  		return 0;
  	}
  	pr_debug("pushing to %p\n", vcc);
  	pr_debug("using %p\n", CLIP_VCC(vcc)->old_push);
  	CLIP_VCC(vcc)->old_push(vcc, skb);
  	return 0;
  }
  
  static const unsigned char llc_oui[] = {
  	0xaa,	/* DSAP: non-ISO */
  	0xaa,	/* SSAP: non-ISO */
  	0x03,	/* Ctrl: Unnumbered Information Command PDU */
  	0x00,	/* OUI: EtherType */
  	0x00,
  	0x00
  };
  
  static void clip_push(struct atm_vcc *vcc, struct sk_buff *skb)
  {
  	struct clip_vcc *clip_vcc = CLIP_VCC(vcc);
  
  	pr_debug("\n");
  
  	if (!clip_devs) {
  		atm_return(vcc, skb->truesize);
  		kfree_skb(skb);
  		return;
  	}
  
  	if (!skb) {
  		pr_debug("removing VCC %p\n", clip_vcc);
  		if (clip_vcc->entry)
  			unlink_clip_vcc(clip_vcc);
  		clip_vcc->old_push(vcc, NULL);	/* pass on the bad news */
  		kfree(clip_vcc);
  		return;
  	}
  	atm_return(vcc, skb->truesize);
  	skb->dev = clip_vcc->entry ? clip_vcc->entry->neigh->dev : clip_devs;
  	/* clip_vcc->entry == NULL if we don't have an IP address yet */
  	if (!skb->dev) {
  		dev_kfree_skb_any(skb);
  		return;
  	}
  	ATM_SKB(skb)->vcc = vcc;
  	skb_reset_mac_header(skb);
  	if (!clip_vcc->encap ||
  	    skb->len < RFC1483LLC_LEN ||
  	    memcmp(skb->data, llc_oui, sizeof(llc_oui)))
  		skb->protocol = htons(ETH_P_IP);
  	else {
  		skb->protocol = ((__be16 *)skb->data)[3];
  		skb_pull(skb, RFC1483LLC_LEN);
  		if (skb->protocol == htons(ETH_P_ARP)) {
  			skb->dev->stats.rx_packets++;
  			skb->dev->stats.rx_bytes += skb->len;
  			clip_arp_rcv(skb);
  			return;
  		}
  	}
  	clip_vcc->last_use = jiffies;
  	skb->dev->stats.rx_packets++;
  	skb->dev->stats.rx_bytes += skb->len;
  	memset(ATM_SKB(skb), 0, sizeof(struct atm_skb_data));
  	netif_rx(skb);
  }
  
  /*
   * Note: these spinlocks _must_not_ block on non-SMP. The only goal is that
   * clip_pop is atomic with respect to the critical section in clip_start_xmit.
   */
  
  static void clip_pop(struct atm_vcc *vcc, struct sk_buff *skb)
  {
  	struct clip_vcc *clip_vcc = CLIP_VCC(vcc);
  	struct net_device *dev = skb->dev;
  	int old;
  	unsigned long flags;
  
  	pr_debug("(vcc %p)\n", vcc);
  	clip_vcc->old_pop(vcc, skb);
  	/* skb->dev == NULL in outbound ARP packets */
  	if (!dev)
  		return;
  	spin_lock_irqsave(&PRIV(dev)->xoff_lock, flags);
  	if (atm_may_send(vcc, 0)) {
  		old = xchg(&clip_vcc->xoff, 0);
  		if (old)
  			netif_wake_queue(dev);
  	}
  	spin_unlock_irqrestore(&PRIV(dev)->xoff_lock, flags);
  }
  
  static void clip_neigh_solicit(struct neighbour *neigh, struct sk_buff *skb)
  {
  	__be32 *ip = (__be32 *) neigh->primary_key;
  
  	pr_debug("(neigh %p, skb %p)\n", neigh, skb);
  	to_atmarpd(act_need, PRIV(neigh->dev)->number, *ip);
  }
  
  static void clip_neigh_error(struct neighbour *neigh, struct sk_buff *skb)
  {
  #ifndef CONFIG_ATM_CLIP_NO_ICMP
  	icmp_send(skb, ICMP_DEST_UNREACH, ICMP_HOST_UNREACH, 0);
  #endif
  	kfree_skb(skb);
  }
  
  static const struct neigh_ops clip_neigh_ops = {
  	.family =		AF_INET,
  	.solicit =		clip_neigh_solicit,
  	.error_report =		clip_neigh_error,
  	.output =		neigh_direct_output,
  	.connected_output =	neigh_direct_output,
  };
  
  static int clip_constructor(struct net_device *dev, struct neighbour *neigh)
  {
  	struct atmarp_entry *entry = neighbour_priv(neigh);
  
  	if (neigh->tbl->family != AF_INET)
  		return -EINVAL;
  
  	if (neigh->type != RTN_UNICAST)
  		return -EINVAL;
  
  	neigh->nud_state = NUD_NONE;
  	neigh->ops = &clip_neigh_ops;
  	neigh->output = neigh->ops->output;
  	entry->neigh = neigh;
  	entry->vccs = NULL;
  	entry->expires = jiffies - 1;
  
  	return 0;
  }
  
  /* @@@ copy bh locking from arp.c -- need to bh-enable atm code before */
  
  /*
   * We play with the resolve flag: 0 and 1 have the usual meaning, but -1 means
   * to allocate the neighbour entry but not to ask atmarpd for resolution. Also,
   * don't increment the usage count. This is used to create entries in
   * clip_setentry.
   */
  
  static int clip_encap(struct atm_vcc *vcc, int mode)
  {
  	if (!CLIP_VCC(vcc))
  		return -EBADFD;
  
  	CLIP_VCC(vcc)->encap = mode;
  	return 0;
  }
  
  static netdev_tx_t clip_start_xmit(struct sk_buff *skb,
  				   struct net_device *dev)
  {
  	struct clip_priv *clip_priv = PRIV(dev);
  	struct dst_entry *dst = skb_dst(skb);
  	struct atmarp_entry *entry;
  	struct neighbour *n;
  	struct atm_vcc *vcc;
  	struct rtable *rt;
  	__be32 *daddr;
  	int old;
  	unsigned long flags;
  
  	pr_debug("(skb %p)\n", skb);
  	if (!dst) {
  		pr_err("skb_dst(skb) == NULL\n");
  		dev_kfree_skb(skb);
  		dev->stats.tx_dropped++;
  		return NETDEV_TX_OK;
  	}
  	rt = (struct rtable *) dst;
  	if (rt->rt_gateway)
  		daddr = &rt->rt_gateway;
  	else
  		daddr = &ip_hdr(skb)->daddr;
  	n = dst_neigh_lookup(dst, daddr);
  	if (!n) {
  		pr_err("NO NEIGHBOUR !\n");
  		dev_kfree_skb(skb);
  		dev->stats.tx_dropped++;
  		return NETDEV_TX_OK;
  	}
  	entry = neighbour_priv(n);
  	if (!entry->vccs) {
  		if (time_after(jiffies, entry->expires)) {
  			/* should be resolved */
  			entry->expires = jiffies + ATMARP_RETRY_DELAY * HZ;
  			to_atmarpd(act_need, PRIV(dev)->number, *((__be32 *)n->primary_key));
  		}
  		if (entry->neigh->arp_queue.qlen < ATMARP_MAX_UNRES_PACKETS)
  			skb_queue_tail(&entry->neigh->arp_queue, skb);
  		else {
  			dev_kfree_skb(skb);
  			dev->stats.tx_dropped++;
  		}
  		goto out_release_neigh;
  	}
  	pr_debug("neigh %p, vccs %p\n", entry, entry->vccs);
  	ATM_SKB(skb)->vcc = vcc = entry->vccs->vcc;
  	pr_debug("using neighbour %p, vcc %p\n", n, vcc);
  	if (entry->vccs->encap) {
  		void *here;
  
  		here = skb_push(skb, RFC1483LLC_LEN);
  		memcpy(here, llc_oui, sizeof(llc_oui));
  		((__be16 *) here)[3] = skb->protocol;
  	}
  	refcount_add(skb->truesize, &sk_atm(vcc)->sk_wmem_alloc);
  	ATM_SKB(skb)->atm_options = vcc->atm_options;
  	entry->vccs->last_use = jiffies;
  	pr_debug("atm_skb(%p)->vcc(%p)->dev(%p)\n", skb, vcc, vcc->dev);
  	old = xchg(&entry->vccs->xoff, 1);	/* assume XOFF ... */
  	if (old) {
  		pr_warn("XOFF->XOFF transition\n");
  		goto out_release_neigh;
  	}
  	dev->stats.tx_packets++;
  	dev->stats.tx_bytes += skb->len;
  	vcc->send(vcc, skb);
  	if (atm_may_send(vcc, 0)) {
  		entry->vccs->xoff = 0;
  		goto out_release_neigh;
  	}
  	spin_lock_irqsave(&clip_priv->xoff_lock, flags);
  	netif_stop_queue(dev);	/* XOFF -> throttle immediately */
  	barrier();
  	if (!entry->vccs->xoff)
  		netif_start_queue(dev);
  	/* Oh, we just raced with clip_pop. netif_start_queue should be
  	   good enough, because nothing should really be asleep because
  	   of the brief netif_stop_queue. If this isn't true or if it
  	   changes, use netif_wake_queue instead. */
  	spin_unlock_irqrestore(&clip_priv->xoff_lock, flags);
  out_release_neigh:
  	neigh_release(n);
  	return NETDEV_TX_OK;
  }
  
  static int clip_mkip(struct atm_vcc *vcc, int timeout)
  {
  	struct clip_vcc *clip_vcc;
  
  	if (!vcc->push)
  		return -EBADFD;
  	clip_vcc = kmalloc(sizeof(struct clip_vcc), GFP_KERNEL);
  	if (!clip_vcc)
  		return -ENOMEM;
  	pr_debug("%p vcc %p\n", clip_vcc, vcc);
  	clip_vcc->vcc = vcc;
  	vcc->user_back = clip_vcc;
  	set_bit(ATM_VF_IS_CLIP, &vcc->flags);
  	clip_vcc->entry = NULL;
  	clip_vcc->xoff = 0;
  	clip_vcc->encap = 1;
  	clip_vcc->last_use = jiffies;
  	clip_vcc->idle_timeout = timeout * HZ;
  	clip_vcc->old_push = vcc->push;
  	clip_vcc->old_pop = vcc->pop;
  	vcc->push = clip_push;
  	vcc->pop = clip_pop;
  
  	/* re-process everything received between connection setup and MKIP */
  	vcc_process_recv_queue(vcc);
  
  	return 0;
  }
  
  static int clip_setentry(struct atm_vcc *vcc, __be32 ip)
  {
  	struct neighbour *neigh;
  	struct atmarp_entry *entry;
  	int error;
  	struct clip_vcc *clip_vcc;
  	struct rtable *rt;
  
  	if (vcc->push != clip_push) {
  		pr_warn("non-CLIP VCC\n");
  		return -EBADF;
  	}
  	clip_vcc = CLIP_VCC(vcc);
  	if (!ip) {
  		if (!clip_vcc->entry) {
  			pr_err("hiding hidden ATMARP entry\n");
  			return 0;
  		}
  		pr_debug("remove\n");
  		unlink_clip_vcc(clip_vcc);
  		return 0;
  	}
  	rt = ip_route_output(&init_net, ip, 0, 1, 0);
  	if (IS_ERR(rt))
  		return PTR_ERR(rt);
  	neigh = __neigh_lookup(&arp_tbl, &ip, rt->dst.dev, 1);
  	ip_rt_put(rt);
  	if (!neigh)
  		return -ENOMEM;
  	entry = neighbour_priv(neigh);
  	if (entry != clip_vcc->entry) {
  		if (!clip_vcc->entry)
  			pr_debug("add\n");
  		else {
  			pr_debug("update\n");
  			unlink_clip_vcc(clip_vcc);
  		}
  		link_vcc(clip_vcc, entry);
  	}
  	error = neigh_update(neigh, llc_oui, NUD_PERMANENT,
  			     NEIGH_UPDATE_F_OVERRIDE | NEIGH_UPDATE_F_ADMIN, 0);
  	neigh_release(neigh);
  	return error;
  }
  
  static const struct net_device_ops clip_netdev_ops = {
  	.ndo_start_xmit		= clip_start_xmit,
  	.ndo_neigh_construct	= clip_constructor,
  };
  
  static void clip_setup(struct net_device *dev)
  {
  	dev->netdev_ops = &clip_netdev_ops;
  	dev->type = ARPHRD_ATM;
  	dev->neigh_priv_len = sizeof(struct atmarp_entry);
  	dev->hard_header_len = RFC1483LLC_LEN;
  	dev->mtu = RFC1626_MTU;
  	dev->tx_queue_len = 100;	/* "normal" queue (packets) */
  	/* When using a "real" qdisc, the qdisc determines the queue */
  	/* length. tx_queue_len is only used for the default case, */
  	/* without any more elaborate queuing. 100 is a reasonable */
  	/* compromise between decent burst-tolerance and protection */
  	/* against memory hogs. */
  	netif_keep_dst(dev);
  }
  
  static int clip_create(int number)
  {
  	struct net_device *dev;
  	struct clip_priv *clip_priv;
  	int error;
  
  	if (number != -1) {
  		for (dev = clip_devs; dev; dev = PRIV(dev)->next)
  			if (PRIV(dev)->number == number)
  				return -EEXIST;
  	} else {
  		number = 0;
  		for (dev = clip_devs; dev; dev = PRIV(dev)->next)
  			if (PRIV(dev)->number >= number)
  				number = PRIV(dev)->number + 1;
  	}
  	dev = alloc_netdev(sizeof(struct clip_priv), "", NET_NAME_UNKNOWN,
  			   clip_setup);
  	if (!dev)
  		return -ENOMEM;
  	clip_priv = PRIV(dev);
  	sprintf(dev->name, "atm%d", number);
  	spin_lock_init(&clip_priv->xoff_lock);
  	clip_priv->number = number;
  	error = register_netdev(dev);
  	if (error) {
  		free_netdev(dev);
  		return error;
  	}
  	clip_priv->next = clip_devs;
  	clip_devs = dev;
  	pr_debug("registered (net:%s)\n", dev->name);
  	return number;
  }
  
  static int clip_device_event(struct notifier_block *this, unsigned long event,
  			     void *ptr)
  {
  	struct net_device *dev = netdev_notifier_info_to_dev(ptr);
  
  	if (!net_eq(dev_net(dev), &init_net))
  		return NOTIFY_DONE;
  
  	if (event == NETDEV_UNREGISTER)
  		return NOTIFY_DONE;
  
  	/* ignore non-CLIP devices */
  	if (dev->type != ARPHRD_ATM || dev->netdev_ops != &clip_netdev_ops)
  		return NOTIFY_DONE;
  
  	switch (event) {
  	case NETDEV_UP:
  		pr_debug("NETDEV_UP\n");
  		to_atmarpd(act_up, PRIV(dev)->number, 0);
  		break;
  	case NETDEV_GOING_DOWN:
  		pr_debug("NETDEV_DOWN\n");
  		to_atmarpd(act_down, PRIV(dev)->number, 0);
  		break;
  	case NETDEV_CHANGE:
  	case NETDEV_CHANGEMTU:
  		pr_debug("NETDEV_CHANGE*\n");
  		to_atmarpd(act_change, PRIV(dev)->number, 0);
  		break;
  	}
  	return NOTIFY_DONE;
  }
  
  static int clip_inet_event(struct notifier_block *this, unsigned long event,
  			   void *ifa)
  {
  	struct in_device *in_dev;
  	struct netdev_notifier_info info;
  
  	in_dev = ((struct in_ifaddr *)ifa)->ifa_dev;
  	/*
  	 * Transitions are of the down-change-up type, so it's sufficient to
  	 * handle the change on up.
  	 */
  	if (event != NETDEV_UP)
  		return NOTIFY_DONE;
  	netdev_notifier_info_init(&info, in_dev->dev);
  	return clip_device_event(this, NETDEV_CHANGE, &info);
  }
  
  static struct notifier_block clip_dev_notifier = {
  	.notifier_call = clip_device_event,
  };
  
  
  
  static struct notifier_block clip_inet_notifier = {
  	.notifier_call = clip_inet_event,
  };
  
  
  
  static void atmarpd_close(struct atm_vcc *vcc)
  {
  	pr_debug("\n");
  
  	rtnl_lock();
  	atmarpd = NULL;
  	skb_queue_purge(&sk_atm(vcc)->sk_receive_queue);
  	rtnl_unlock();
  
  	pr_debug("(done)\n");
  	module_put(THIS_MODULE);
  }
  
  static const struct atmdev_ops atmarpd_dev_ops = {
  	.close = atmarpd_close
  };
  
  
  static struct atm_dev atmarpd_dev = {
  	.ops =			&atmarpd_dev_ops,
  	.type =			"arpd",
  	.number = 		999,
  	.lock =			__SPIN_LOCK_UNLOCKED(atmarpd_dev.lock)
  };
  
  
  static int atm_init_atmarp(struct atm_vcc *vcc)
  {
  	rtnl_lock();
  	if (atmarpd) {
  		rtnl_unlock();
  		return -EADDRINUSE;
  	}
  
  	mod_timer(&idle_timer, jiffies + CLIP_CHECK_INTERVAL * HZ);
  
  	atmarpd = vcc;
  	set_bit(ATM_VF_META, &vcc->flags);
  	set_bit(ATM_VF_READY, &vcc->flags);
  	    /* allow replies and avoid getting closed if signaling dies */
  	vcc->dev = &atmarpd_dev;
  	vcc_insert_socket(sk_atm(vcc));
  	vcc->push = NULL;
  	vcc->pop = NULL; /* crash */
  	vcc->push_oam = NULL; /* crash */
  	rtnl_unlock();
  	return 0;
  }
  
  static int clip_ioctl(struct socket *sock, unsigned int cmd, unsigned long arg)
  {
  	struct atm_vcc *vcc = ATM_SD(sock);
  	int err = 0;
  
  	switch (cmd) {
  	case SIOCMKCLIP:
  	case ATMARPD_CTRL:
  	case ATMARP_MKIP:
  	case ATMARP_SETENTRY:
  	case ATMARP_ENCAP:
  		if (!capable(CAP_NET_ADMIN))
  			return -EPERM;
  		break;
  	default:
  		return -ENOIOCTLCMD;
  	}
  
  	switch (cmd) {
  	case SIOCMKCLIP:
  		err = clip_create(arg);
  		break;
  	case ATMARPD_CTRL:
  		err = atm_init_atmarp(vcc);
  		if (!err) {
  			sock->state = SS_CONNECTED;
  			__module_get(THIS_MODULE);
  		}
  		break;
  	case ATMARP_MKIP:
  		err = clip_mkip(vcc, arg);
  		break;
  	case ATMARP_SETENTRY:
  		err = clip_setentry(vcc, (__force __be32)arg);
  		break;
  	case ATMARP_ENCAP:
  		err = clip_encap(vcc, arg);
  		break;
  	}
  	return err;
  }
  
  static struct atm_ioctl clip_ioctl_ops = {
  	.owner = THIS_MODULE,
  	.ioctl = clip_ioctl,
  };
  
  #ifdef CONFIG_PROC_FS
  
  static void svc_addr(struct seq_file *seq, struct sockaddr_atmsvc *addr)
  {
  	static int code[] = { 1, 2, 10, 6, 1, 0 };
  	static int e164[] = { 1, 8, 4, 6, 1, 0 };
  
  	if (*addr->sas_addr.pub) {
  		seq_printf(seq, "%s", addr->sas_addr.pub);
  		if (*addr->sas_addr.prv)
  			seq_putc(seq, '+');
  	} else if (!*addr->sas_addr.prv) {
  		seq_printf(seq, "%s", "(none)");
  		return;
  	}
  	if (*addr->sas_addr.prv) {
  		unsigned char *prv = addr->sas_addr.prv;
  		int *fields;
  		int i, j;
  
  		fields = *prv == ATM_AFI_E164 ? e164 : code;
  		for (i = 0; fields[i]; i++) {
  			for (j = fields[i]; j; j--)
  				seq_printf(seq, "%02X", *prv++);
  			if (fields[i + 1])
  				seq_putc(seq, '.');
  		}
  	}
  }
  
  /* This means the neighbour entry has no attached VCC objects. */
  #define SEQ_NO_VCC_TOKEN	((void *) 2)
  
  static void atmarp_info(struct seq_file *seq, struct neighbour *n,
  			struct atmarp_entry *entry, struct clip_vcc *clip_vcc)
  {
  	struct net_device *dev = n->dev;
  	unsigned long exp;
  	char buf[17];
  	int svc, llc, off;
  
  	svc = ((clip_vcc == SEQ_NO_VCC_TOKEN) ||
  	       (sk_atm(clip_vcc->vcc)->sk_family == AF_ATMSVC));
  
  	llc = ((clip_vcc == SEQ_NO_VCC_TOKEN) || clip_vcc->encap);
  
  	if (clip_vcc == SEQ_NO_VCC_TOKEN)
  		exp = entry->neigh->used;
  	else
  		exp = clip_vcc->last_use;
  
  	exp = (jiffies - exp) / HZ;
  
  	seq_printf(seq, "%-6s%-4s%-4s%5ld ",
  		   dev->name, svc ? "SVC" : "PVC", llc ? "LLC" : "NULL", exp);
  
  	off = scnprintf(buf, sizeof(buf) - 1, "%pI4", n->primary_key);
  	while (off < 16)
  		buf[off++] = ' ';
  	buf[off] = '\0';
  	seq_printf(seq, "%s", buf);
  
  	if (clip_vcc == SEQ_NO_VCC_TOKEN) {
  		if (time_before(jiffies, entry->expires))
  			seq_printf(seq, "(resolving)\n");
  		else
  			seq_printf(seq, "(expired, ref %d)\n",
  				   refcount_read(&entry->neigh->refcnt));
  	} else if (!svc) {
  		seq_printf(seq, "%d.%d.%d\n",
  			   clip_vcc->vcc->dev->number,
  			   clip_vcc->vcc->vpi, clip_vcc->vcc->vci);
  	} else {
  		svc_addr(seq, &clip_vcc->vcc->remote);
  		seq_putc(seq, '\n');
  	}
  }
  
  struct clip_seq_state {
  	/* This member must be first. */
  	struct neigh_seq_state ns;
  
  	/* Local to clip specific iteration. */
  	struct clip_vcc *vcc;
  };
  
  static struct clip_vcc *clip_seq_next_vcc(struct atmarp_entry *e,
  					  struct clip_vcc *curr)
  {
  	if (!curr) {
  		curr = e->vccs;
  		if (!curr)
  			return SEQ_NO_VCC_TOKEN;
  		return curr;
  	}
  	if (curr == SEQ_NO_VCC_TOKEN)
  		return NULL;
  
  	curr = curr->next;
  
  	return curr;
  }
  
  static void *clip_seq_vcc_walk(struct clip_seq_state *state,
  			       struct atmarp_entry *e, loff_t * pos)
  {
  	struct clip_vcc *vcc = state->vcc;
  
  	vcc = clip_seq_next_vcc(e, vcc);
  	if (vcc && pos != NULL) {
  		while (*pos) {
  			vcc = clip_seq_next_vcc(e, vcc);
  			if (!vcc)
  				break;
  			--(*pos);
  		}
  	}
  	state->vcc = vcc;
  
  	return vcc;
  }
  
  static void *clip_seq_sub_iter(struct neigh_seq_state *_state,
  			       struct neighbour *n, loff_t * pos)
  {
  	struct clip_seq_state *state = (struct clip_seq_state *)_state;
  
  	if (n->dev->type != ARPHRD_ATM)
  		return NULL;
  
  	return clip_seq_vcc_walk(state, neighbour_priv(n), pos);
  }
  
  static void *clip_seq_start(struct seq_file *seq, loff_t * pos)
  {
  	struct clip_seq_state *state = seq->private;
  	state->ns.neigh_sub_iter = clip_seq_sub_iter;
  	return neigh_seq_start(seq, pos, &arp_tbl, NEIGH_SEQ_NEIGH_ONLY);
  }
  
  static int clip_seq_show(struct seq_file *seq, void *v)
  {
  	static char atm_arp_banner[] =
  	    "IPitf TypeEncp Idle IP address      ATM address\n";
  
  	if (v == SEQ_START_TOKEN) {
  		seq_puts(seq, atm_arp_banner);
  	} else {
  		struct clip_seq_state *state = seq->private;
  		struct clip_vcc *vcc = state->vcc;
  		struct neighbour *n = v;
  
  		atmarp_info(seq, n, neighbour_priv(n), vcc);
  	}
  	return 0;
  }
  
  static const struct seq_operations arp_seq_ops = {
  	.start	= clip_seq_start,
  	.next	= neigh_seq_next,
  	.stop	= neigh_seq_stop,
  	.show	= clip_seq_show,
  };
  #endif
  
  static void atm_clip_exit_noproc(void);
  
  static int __init atm_clip_init(void)
  {
  	register_atm_ioctl(&clip_ioctl_ops);
  	register_netdevice_notifier(&clip_dev_notifier);
  	register_inetaddr_notifier(&clip_inet_notifier);
  
  	timer_setup(&idle_timer, idle_timer_check, 0);
  
  #ifdef CONFIG_PROC_FS
  	{
  		struct proc_dir_entry *p;
  
  		p = proc_create_net("arp", 0444, atm_proc_root, &arp_seq_ops,
  				sizeof(struct clip_seq_state));
  		if (!p) {
  			pr_err("Unable to initialize /proc/net/atm/arp\n");
  			atm_clip_exit_noproc();
  			return -ENOMEM;
  		}
  	}
  #endif
  
  	return 0;
  }
  
  static void atm_clip_exit_noproc(void)
  {
  	struct net_device *dev, *next;
  
  	unregister_inetaddr_notifier(&clip_inet_notifier);
  	unregister_netdevice_notifier(&clip_dev_notifier);
  
  	deregister_atm_ioctl(&clip_ioctl_ops);
  
  	/* First, stop the idle timer, so it stops banging
  	 * on the table.
  	 */
  	del_timer_sync(&idle_timer);
  
  	dev = clip_devs;
  	while (dev) {
  		next = PRIV(dev)->next;
  		unregister_netdev(dev);
  		free_netdev(dev);
  		dev = next;
  	}
  }
  
  static void __exit atm_clip_exit(void)
  {
  	remove_proc_entry("arp", atm_proc_root);
  
  	atm_clip_exit_noproc();
  }
  
  module_init(atm_clip_init);
  module_exit(atm_clip_exit);
  MODULE_AUTHOR("Werner Almesberger");
  MODULE_DESCRIPTION("Classical/IP over ATM interface");
  MODULE_LICENSE("GPL");
  