/*
   *	Generic address resolution entity
   *
   *	Authors:
   *	Pedro Roque		<roque@di.fc.ul.pt>
   *	Alexey Kuznetsov	<kuznet@ms2.inr.ac.ru>
   *
   *	This program is free software; you can redistribute it and/or
   *      modify it under the terms of the GNU General Public License
   *      as published by the Free Software Foundation; either version
   *      2 of the License, or (at your option) any later version.
   *
   *	Fixes:
   *	Vitaly E. Lavrov	releasing NULL neighbor in neigh_add.
   *	Harald Welte		Add neighbour cache statistics like rtstat
   */

  #include <linux/slab.h>

  #include <linux/types.h>
  #include <linux/kernel.h>
  #include <linux/module.h>
  #include <linux/socket.h>

  #include <linux/netdevice.h>
  #include <linux/proc_fs.h>
  #ifdef CONFIG_SYSCTL
  #include <linux/sysctl.h>
  #endif
  #include <linux/times.h>

  #include <net/net_namespace.h>

  #include <net/neighbour.h>
  #include <net/dst.h>
  #include <net/sock.h>

  #include <net/netevent.h>

  #include <net/netlink.h>

  #include <linux/rtnetlink.h>
  #include <linux/random.h>

  #include <linux/string.h>

  #include <linux/log2.h>

  
  #define NEIGH_DEBUG 1
  
  #define NEIGH_PRINTK(x...) printk(x)
  #define NEIGH_NOPRINTK(x...) do { ; } while(0)

  #define NEIGH_PRINTK1 NEIGH_NOPRINTK
  #define NEIGH_PRINTK2 NEIGH_NOPRINTK
  
  #if NEIGH_DEBUG >= 1
  #undef NEIGH_PRINTK1
  #define NEIGH_PRINTK1 NEIGH_PRINTK
  #endif
  #if NEIGH_DEBUG >= 2
  #undef NEIGH_PRINTK2
  #define NEIGH_PRINTK2 NEIGH_PRINTK
  #endif
  
  #define PNEIGH_HASHMASK		0xF
  
  static void neigh_timer_handler(unsigned long arg);

  static void __neigh_notify(struct neighbour *n, int type, int flags);
  static void neigh_update_notify(struct neighbour *neigh);

  static int pneigh_ifdown(struct neigh_table *tbl, struct net_device *dev);

  
  static struct neigh_table *neigh_tables;

  #ifdef CONFIG_PROC_FS

  static const struct file_operations neigh_stat_seq_fops;

  #endif

  
  /*
     Neighbour hash table buckets are protected with rwlock tbl->lock.
  
     - All the scans/updates to hash buckets MUST be made under this lock.
     - NOTHING clever should be made under this lock: no callbacks
       to protocol backends, no attempts to send something to network.
       It will result in deadlocks, if backend/driver wants to use neighbour
       cache.
     - If the entry requires some non-trivial actions, increase
       its reference count and release table lock.
  
     Neighbour entries are protected:
     - with reference count.
     - with rwlock neigh->lock
  
     Reference count prevents destruction.
  
     neigh->lock mainly serializes ll address data and its validity state.
     However, the same lock is used to protect another entry fields:
      - timer
      - resolution queue
  
     Again, nothing clever shall be made under neigh->lock,
     the most complicated procedure, which we allow is dev->hard_header.
     It is supposed, that dev->hard_header is simplistic and does
     not make callbacks to neighbour tables.
  
     The last lock is neigh_tbl_lock. It is pure SMP lock, protecting
     list of neighbour tables. This list is used only in process context,
   */
  
  static DEFINE_RWLOCK(neigh_tbl_lock);

  static int neigh_blackhole(struct neighbour *neigh, struct sk_buff *skb)

  {
  	kfree_skb(skb);
  	return -ENETDOWN;
  }

  static void neigh_cleanup_and_release(struct neighbour *neigh)
  {
  	if (neigh->parms->neigh_cleanup)
  		neigh->parms->neigh_cleanup(neigh);

  	__neigh_notify(neigh, RTM_DELNEIGH, 0);

  	neigh_release(neigh);
  }

  /*
   * It is random distribution in the interval (1/2)*base...(3/2)*base.
   * It corresponds to default IPv6 settings and is not overridable,
   * because it is really reasonable choice.
   */
  
  unsigned long neigh_rand_reach_time(unsigned long base)
  {

  	return base ? (net_random() % base) + (base >> 1) : 0;

  }

  EXPORT_SYMBOL(neigh_rand_reach_time);

  
  
  static int neigh_forced_gc(struct neigh_table *tbl)
  {
  	int shrunk = 0;
  	int i;

  	struct neigh_hash_table *nht;

  
  	NEIGH_CACHE_STAT_INC(tbl, forced_gc_runs);
  
  	write_lock_bh(&tbl->lock);

  	nht = rcu_dereference_protected(tbl->nht,
  					lockdep_is_held(&tbl->lock));

  	for (i = 0; i < (1 << nht->hash_shift); i++) {

  		struct neighbour *n;
  		struct neighbour __rcu **np;

  		np = &nht->hash_buckets[i];

  		while ((n = rcu_dereference_protected(*np,
  					lockdep_is_held(&tbl->lock))) != NULL) {

  			/* Neighbour record may be discarded if:
  			 * - nobody refers to it.
  			 * - it is not permanent
  			 */
  			write_lock(&n->lock);
  			if (atomic_read(&n->refcnt) == 1 &&
  			    !(n->nud_state & NUD_PERMANENT)) {

  				rcu_assign_pointer(*np,
  					rcu_dereference_protected(n->next,
  						  lockdep_is_held(&tbl->lock)));

  				n->dead = 1;
  				shrunk	= 1;
  				write_unlock(&n->lock);

  				neigh_cleanup_and_release(n);

  				continue;
  			}
  			write_unlock(&n->lock);
  			np = &n->next;
  		}
  	}
  
  	tbl->last_flush = jiffies;
  
  	write_unlock_bh(&tbl->lock);
  
  	return shrunk;
  }

  static void neigh_add_timer(struct neighbour *n, unsigned long when)
  {
  	neigh_hold(n);
  	if (unlikely(mod_timer(&n->timer, when))) {
  		printk("NEIGH: BUG, double timer add, state is %x
  ",
  		       n->nud_state);
  		dump_stack();
  	}
  }

  static int neigh_del_timer(struct neighbour *n)
  {
  	if ((n->nud_state & NUD_IN_TIMER) &&
  	    del_timer(&n->timer)) {
  		neigh_release(n);
  		return 1;
  	}
  	return 0;
  }
  
  static void pneigh_queue_purge(struct sk_buff_head *list)
  {
  	struct sk_buff *skb;
  
  	while ((skb = skb_dequeue(list)) != NULL) {
  		dev_put(skb->dev);
  		kfree_skb(skb);
  	}
  }

  static void neigh_flush_dev(struct neigh_table *tbl, struct net_device *dev)

  {
  	int i;

  	struct neigh_hash_table *nht;

  	nht = rcu_dereference_protected(tbl->nht,
  					lockdep_is_held(&tbl->lock));

  	for (i = 0; i < (1 << nht->hash_shift); i++) {

  		struct neighbour *n;
  		struct neighbour __rcu **np = &nht->hash_buckets[i];

  		while ((n = rcu_dereference_protected(*np,
  					lockdep_is_held(&tbl->lock))) != NULL) {

  			if (dev && n->dev != dev) {
  				np = &n->next;
  				continue;
  			}

  			rcu_assign_pointer(*np,
  				   rcu_dereference_protected(n->next,
  						lockdep_is_held(&tbl->lock)));

  			write_lock(&n->lock);
  			neigh_del_timer(n);
  			n->dead = 1;
  
  			if (atomic_read(&n->refcnt) != 1) {
  				/* The most unpleasant situation.
  				   We must destroy neighbour entry,
  				   but someone still uses it.
  
  				   The destroy will be delayed until
  				   the last user releases us, but
  				   we must kill timers etc. and move
  				   it to safe state.
  				 */
  				skb_queue_purge(&n->arp_queue);

  				n->arp_queue_len_bytes = 0;

  				n->output = neigh_blackhole;
  				if (n->nud_state & NUD_VALID)
  					n->nud_state = NUD_NOARP;
  				else
  					n->nud_state = NUD_NONE;
  				NEIGH_PRINTK2("neigh %p is stray.
  ", n);
  			}
  			write_unlock(&n->lock);

  			neigh_cleanup_and_release(n);

  		}
  	}

  }

  void neigh_changeaddr(struct neigh_table *tbl, struct net_device *dev)
  {
  	write_lock_bh(&tbl->lock);
  	neigh_flush_dev(tbl, dev);
  	write_unlock_bh(&tbl->lock);
  }

  EXPORT_SYMBOL(neigh_changeaddr);

  
  int neigh_ifdown(struct neigh_table *tbl, struct net_device *dev)
  {
  	write_lock_bh(&tbl->lock);
  	neigh_flush_dev(tbl, dev);

  	pneigh_ifdown(tbl, dev);
  	write_unlock_bh(&tbl->lock);
  
  	del_timer_sync(&tbl->proxy_timer);
  	pneigh_queue_purge(&tbl->proxy_queue);
  	return 0;
  }

  EXPORT_SYMBOL(neigh_ifdown);

  static struct neighbour *neigh_alloc(struct neigh_table *tbl, struct net_device *dev)

  {
  	struct neighbour *n = NULL;
  	unsigned long now = jiffies;
  	int entries;
  
  	entries = atomic_inc_return(&tbl->entries) - 1;
  	if (entries >= tbl->gc_thresh3 ||
  	    (entries >= tbl->gc_thresh2 &&
  	     time_after(now, tbl->last_flush + 5 * HZ))) {
  		if (!neigh_forced_gc(tbl) &&
  		    entries >= tbl->gc_thresh3)
  			goto out_entries;
  	}

  	if (tbl->entry_size)
  		n = kzalloc(tbl->entry_size, GFP_ATOMIC);
  	else {
  		int sz = sizeof(*n) + tbl->key_len;
  
  		sz = ALIGN(sz, NEIGH_PRIV_ALIGN);
  		sz += dev->neigh_priv_len;
  		n = kzalloc(sz, GFP_ATOMIC);
  	}

  	if (!n)
  		goto out_entries;

  	skb_queue_head_init(&n->arp_queue);
  	rwlock_init(&n->lock);

  	seqlock_init(&n->ha_lock);

  	n->updated	  = n->used = now;
  	n->nud_state	  = NUD_NONE;
  	n->output	  = neigh_blackhole;

  	seqlock_init(&n->hh.hh_lock);

  	n->parms	  = neigh_parms_clone(&tbl->parms);

  	setup_timer(&n->timer, neigh_timer_handler, (unsigned long)n);

  
  	NEIGH_CACHE_STAT_INC(tbl, allocs);
  	n->tbl		  = tbl;
  	atomic_set(&n->refcnt, 1);
  	n->dead		  = 1;
  out:
  	return n;
  
  out_entries:
  	atomic_dec(&tbl->entries);
  	goto out;
  }

  static void neigh_get_hash_rnd(u32 *x)
  {
  	get_random_bytes(x, sizeof(*x));
  	*x |= 1;
  }

  static struct neigh_hash_table *neigh_hash_alloc(unsigned int shift)

  {

  	size_t size = (1 << shift) * sizeof(struct neighbour *);

  	struct neigh_hash_table *ret;

  	struct neighbour __rcu **buckets;

  	int i;

  	ret = kmalloc(sizeof(*ret), GFP_ATOMIC);
  	if (!ret)
  		return NULL;
  	if (size <= PAGE_SIZE)
  		buckets = kzalloc(size, GFP_ATOMIC);
  	else

  		buckets = (struct neighbour __rcu **)

  			  __get_free_pages(GFP_ATOMIC | __GFP_ZERO,
  					   get_order(size));
  	if (!buckets) {
  		kfree(ret);
  		return NULL;

  	}

  	ret->hash_buckets = buckets;

  	ret->hash_shift = shift;

  	for (i = 0; i < NEIGH_NUM_HASH_RND; i++)
  		neigh_get_hash_rnd(&ret->hash_rnd[i]);

  	return ret;
  }

  static void neigh_hash_free_rcu(struct rcu_head *head)

  {

  	struct neigh_hash_table *nht = container_of(head,
  						    struct neigh_hash_table,
  						    rcu);

  	size_t size = (1 << nht->hash_shift) * sizeof(struct neighbour *);

  	struct neighbour __rcu **buckets = nht->hash_buckets;

  
  	if (size <= PAGE_SIZE)

  		kfree(buckets);

  	else

  		free_pages((unsigned long)buckets, get_order(size));
  	kfree(nht);

  }

  static struct neigh_hash_table *neigh_hash_grow(struct neigh_table *tbl,

  						unsigned long new_shift)

  {

  	unsigned int i, hash;
  	struct neigh_hash_table *new_nht, *old_nht;

  
  	NEIGH_CACHE_STAT_INC(tbl, hash_grows);

  	old_nht = rcu_dereference_protected(tbl->nht,
  					    lockdep_is_held(&tbl->lock));

  	new_nht = neigh_hash_alloc(new_shift);

  	if (!new_nht)
  		return old_nht;

  	for (i = 0; i < (1 << old_nht->hash_shift); i++) {

  		struct neighbour *n, *next;

  		for (n = rcu_dereference_protected(old_nht->hash_buckets[i],
  						   lockdep_is_held(&tbl->lock));

  		     n != NULL;
  		     n = next) {
  			hash = tbl->hash(n->primary_key, n->dev,
  					 new_nht->hash_rnd);

  			hash >>= (32 - new_nht->hash_shift);

  			next = rcu_dereference_protected(n->next,
  						lockdep_is_held(&tbl->lock));
  
  			rcu_assign_pointer(n->next,
  					   rcu_dereference_protected(
  						new_nht->hash_buckets[hash],
  						lockdep_is_held(&tbl->lock)));
  			rcu_assign_pointer(new_nht->hash_buckets[hash], n);

  		}
  	}

  	rcu_assign_pointer(tbl->nht, new_nht);
  	call_rcu(&old_nht->rcu, neigh_hash_free_rcu);
  	return new_nht;

  }
  
  struct neighbour *neigh_lookup(struct neigh_table *tbl, const void *pkey,
  			       struct net_device *dev)
  {
  	struct neighbour *n;
  	int key_len = tbl->key_len;

  	u32 hash_val;

  	struct neigh_hash_table *nht;

  	NEIGH_CACHE_STAT_INC(tbl, lookups);

  	rcu_read_lock_bh();
  	nht = rcu_dereference_bh(tbl->nht);

  	hash_val = tbl->hash(pkey, dev, nht->hash_rnd) >> (32 - nht->hash_shift);

  
  	for (n = rcu_dereference_bh(nht->hash_buckets[hash_val]);
  	     n != NULL;
  	     n = rcu_dereference_bh(n->next)) {

  		if (dev == n->dev && !memcmp(n->primary_key, pkey, key_len)) {

  			if (!atomic_inc_not_zero(&n->refcnt))
  				n = NULL;

  			NEIGH_CACHE_STAT_INC(tbl, hits);
  			break;
  		}
  	}

  	rcu_read_unlock_bh();

  	return n;
  }

  EXPORT_SYMBOL(neigh_lookup);

  struct neighbour *neigh_lookup_nodev(struct neigh_table *tbl, struct net *net,
  				     const void *pkey)

  {
  	struct neighbour *n;
  	int key_len = tbl->key_len;

  	u32 hash_val;

  	struct neigh_hash_table *nht;

  
  	NEIGH_CACHE_STAT_INC(tbl, lookups);

  	rcu_read_lock_bh();
  	nht = rcu_dereference_bh(tbl->nht);

  	hash_val = tbl->hash(pkey, NULL, nht->hash_rnd) >> (32 - nht->hash_shift);

  
  	for (n = rcu_dereference_bh(nht->hash_buckets[hash_val]);
  	     n != NULL;
  	     n = rcu_dereference_bh(n->next)) {

  		if (!memcmp(n->primary_key, pkey, key_len) &&

  		    net_eq(dev_net(n->dev), net)) {

  			if (!atomic_inc_not_zero(&n->refcnt))
  				n = NULL;

  			NEIGH_CACHE_STAT_INC(tbl, hits);
  			break;
  		}
  	}

  	rcu_read_unlock_bh();

  	return n;
  }

  EXPORT_SYMBOL(neigh_lookup_nodev);

  
  struct neighbour *neigh_create(struct neigh_table *tbl, const void *pkey,
  			       struct net_device *dev)
  {
  	u32 hash_val;
  	int key_len = tbl->key_len;
  	int error;

  	struct neighbour *n1, *rc, *n = neigh_alloc(tbl, dev);

  	struct neigh_hash_table *nht;

  
  	if (!n) {
  		rc = ERR_PTR(-ENOBUFS);
  		goto out;
  	}
  
  	memcpy(n->primary_key, pkey, key_len);
  	n->dev = dev;
  	dev_hold(dev);
  
  	/* Protocol specific setup. */
  	if (tbl->constructor &&	(error = tbl->constructor(n)) < 0) {
  		rc = ERR_PTR(error);
  		goto out_neigh_release;
  	}

  	if (dev->netdev_ops->ndo_neigh_construct) {
  		error = dev->netdev_ops->ndo_neigh_construct(n);
  		if (error < 0) {
  			rc = ERR_PTR(error);
  			goto out_neigh_release;
  		}
  	}

  	/* Device specific setup. */
  	if (n->parms->neigh_setup &&
  	    (error = n->parms->neigh_setup(n)) < 0) {
  		rc = ERR_PTR(error);
  		goto out_neigh_release;
  	}

  	n->confirmed = jiffies - (n->parms->base_reachable_time << 1);
  
  	write_lock_bh(&tbl->lock);

  	nht = rcu_dereference_protected(tbl->nht,
  					lockdep_is_held(&tbl->lock));

  	if (atomic_read(&tbl->entries) > (1 << nht->hash_shift))
  		nht = neigh_hash_grow(tbl, nht->hash_shift + 1);

  	hash_val = tbl->hash(pkey, dev, nht->hash_rnd) >> (32 - nht->hash_shift);

  
  	if (n->parms->dead) {
  		rc = ERR_PTR(-EINVAL);
  		goto out_tbl_unlock;
  	}

  	for (n1 = rcu_dereference_protected(nht->hash_buckets[hash_val],
  					    lockdep_is_held(&tbl->lock));
  	     n1 != NULL;
  	     n1 = rcu_dereference_protected(n1->next,
  			lockdep_is_held(&tbl->lock))) {

  		if (dev == n1->dev && !memcmp(n1->primary_key, pkey, key_len)) {
  			neigh_hold(n1);
  			rc = n1;
  			goto out_tbl_unlock;
  		}
  	}

  	n->dead = 0;
  	neigh_hold(n);

  	rcu_assign_pointer(n->next,
  			   rcu_dereference_protected(nht->hash_buckets[hash_val],
  						     lockdep_is_held(&tbl->lock)));
  	rcu_assign_pointer(nht->hash_buckets[hash_val], n);

  	write_unlock_bh(&tbl->lock);
  	NEIGH_PRINTK2("neigh %p is created.
  ", n);
  	rc = n;
  out:
  	return rc;
  out_tbl_unlock:
  	write_unlock_bh(&tbl->lock);
  out_neigh_release:
  	neigh_release(n);
  	goto out;
  }

  EXPORT_SYMBOL(neigh_create);

  static u32 pneigh_hash(const void *pkey, int key_len)

  {

  	u32 hash_val = *(u32 *)(pkey + key_len - 4);

  	hash_val ^= (hash_val >> 16);
  	hash_val ^= hash_val >> 8;
  	hash_val ^= hash_val >> 4;
  	hash_val &= PNEIGH_HASHMASK;

  	return hash_val;
  }

  static struct pneigh_entry *__pneigh_lookup_1(struct pneigh_entry *n,
  					      struct net *net,
  					      const void *pkey,
  					      int key_len,
  					      struct net_device *dev)
  {
  	while (n) {

  		if (!memcmp(n->key, pkey, key_len) &&

  		    net_eq(pneigh_net(n), net) &&

  		    (n->dev == dev || !n->dev))

  			return n;
  		n = n->next;

  	}

  	return NULL;
  }

  struct pneigh_entry *__pneigh_lookup(struct neigh_table *tbl,
  		struct net *net, const void *pkey, struct net_device *dev)
  {
  	int key_len = tbl->key_len;
  	u32 hash_val = pneigh_hash(pkey, key_len);
  
  	return __pneigh_lookup_1(tbl->phash_buckets[hash_val],
  				 net, pkey, key_len, dev);

  }

  EXPORT_SYMBOL_GPL(__pneigh_lookup);

  struct pneigh_entry * pneigh_lookup(struct neigh_table *tbl,
  				    struct net *net, const void *pkey,

  				    struct net_device *dev, int creat)
  {
  	struct pneigh_entry *n;
  	int key_len = tbl->key_len;

  	u32 hash_val = pneigh_hash(pkey, key_len);

  
  	read_lock_bh(&tbl->lock);

  	n = __pneigh_lookup_1(tbl->phash_buckets[hash_val],
  			      net, pkey, key_len, dev);

  	read_unlock_bh(&tbl->lock);

  
  	if (n || !creat)

  		goto out;

  	ASSERT_RTNL();

  	n = kmalloc(sizeof(*n) + key_len, GFP_KERNEL);
  	if (!n)
  		goto out;

  	write_pnet(&n->net, hold_net(net));

  	memcpy(n->key, pkey, key_len);
  	n->dev = dev;
  	if (dev)
  		dev_hold(dev);
  
  	if (tbl->pconstructor && tbl->pconstructor(n)) {
  		if (dev)
  			dev_put(dev);

  		release_net(net);

  		kfree(n);
  		n = NULL;
  		goto out;
  	}
  
  	write_lock_bh(&tbl->lock);
  	n->next = tbl->phash_buckets[hash_val];
  	tbl->phash_buckets[hash_val] = n;
  	write_unlock_bh(&tbl->lock);
  out:
  	return n;
  }

  EXPORT_SYMBOL(pneigh_lookup);

  int pneigh_delete(struct neigh_table *tbl, struct net *net, const void *pkey,

  		  struct net_device *dev)
  {
  	struct pneigh_entry *n, **np;
  	int key_len = tbl->key_len;

  	u32 hash_val = pneigh_hash(pkey, key_len);

  
  	write_lock_bh(&tbl->lock);
  	for (np = &tbl->phash_buckets[hash_val]; (n = *np) != NULL;
  	     np = &n->next) {

  		if (!memcmp(n->key, pkey, key_len) && n->dev == dev &&

  		    net_eq(pneigh_net(n), net)) {

  			*np = n->next;
  			write_unlock_bh(&tbl->lock);
  			if (tbl->pdestructor)
  				tbl->pdestructor(n);
  			if (n->dev)
  				dev_put(n->dev);

  			release_net(pneigh_net(n));

  			kfree(n);
  			return 0;
  		}
  	}
  	write_unlock_bh(&tbl->lock);
  	return -ENOENT;
  }
  
  static int pneigh_ifdown(struct neigh_table *tbl, struct net_device *dev)
  {
  	struct pneigh_entry *n, **np;
  	u32 h;
  
  	for (h = 0; h <= PNEIGH_HASHMASK; h++) {
  		np = &tbl->phash_buckets[h];
  		while ((n = *np) != NULL) {
  			if (!dev || n->dev == dev) {
  				*np = n->next;
  				if (tbl->pdestructor)
  					tbl->pdestructor(n);
  				if (n->dev)
  					dev_put(n->dev);

  				release_net(pneigh_net(n));

  				kfree(n);
  				continue;
  			}
  			np = &n->next;
  		}
  	}
  	return -ENOENT;
  }

  static void neigh_parms_destroy(struct neigh_parms *parms);
  
  static inline void neigh_parms_put(struct neigh_parms *parms)
  {
  	if (atomic_dec_and_test(&parms->refcnt))
  		neigh_parms_destroy(parms);
  }

  
  /*
   *	neighbour must already be out of the table;
   *
   */
  void neigh_destroy(struct neighbour *neigh)
  {

  	struct net_device *dev = neigh->dev;

  	NEIGH_CACHE_STAT_INC(neigh->tbl, destroys);
  
  	if (!neigh->dead) {
  		printk(KERN_WARNING
  		       "Destroying alive neighbour %p
  ", neigh);
  		dump_stack();
  		return;
  	}
  
  	if (neigh_del_timer(neigh))
  		printk(KERN_WARNING "Impossible event.
  ");

  	skb_queue_purge(&neigh->arp_queue);

  	neigh->arp_queue_len_bytes = 0;

  	if (dev->netdev_ops->ndo_neigh_destroy)
  		dev->netdev_ops->ndo_neigh_destroy(neigh);

  	dev_put(dev);

  	neigh_parms_put(neigh->parms);
  
  	NEIGH_PRINTK2("neigh %p is destroyed.
  ", neigh);
  
  	atomic_dec(&neigh->tbl->entries);

  	kfree_rcu(neigh, rcu);

  }

  EXPORT_SYMBOL(neigh_destroy);

  
  /* Neighbour state is suspicious;
     disable fast path.
  
     Called with write_locked neigh.
   */
  static void neigh_suspect(struct neighbour *neigh)
  {

  	NEIGH_PRINTK2("neigh %p is suspected.
  ", neigh);
  
  	neigh->output = neigh->ops->output;

  }
  
  /* Neighbour state is OK;
     enable fast path.
  
     Called with write_locked neigh.
   */
  static void neigh_connect(struct neighbour *neigh)
  {

  	NEIGH_PRINTK2("neigh %p is connected.
  ", neigh);
  
  	neigh->output = neigh->ops->connected_output;

  }

  static void neigh_periodic_work(struct work_struct *work)

  {

  	struct neigh_table *tbl = container_of(work, struct neigh_table, gc_work.work);

  	struct neighbour *n;
  	struct neighbour __rcu **np;

  	unsigned int i;

  	struct neigh_hash_table *nht;

  
  	NEIGH_CACHE_STAT_INC(tbl, periodic_gc_runs);

  	write_lock_bh(&tbl->lock);

  	nht = rcu_dereference_protected(tbl->nht,
  					lockdep_is_held(&tbl->lock));

  
  	/*
  	 *	periodically recompute ReachableTime from random function
  	 */

  	if (time_after(jiffies, tbl->last_rand + 300 * HZ)) {

  		struct neigh_parms *p;

  		tbl->last_rand = jiffies;

  		for (p = &tbl->parms; p; p = p->next)
  			p->reachable_time =
  				neigh_rand_reach_time(p->base_reachable_time);
  	}

  	for (i = 0 ; i < (1 << nht->hash_shift); i++) {

  		np = &nht->hash_buckets[i];

  		while ((n = rcu_dereference_protected(*np,
  				lockdep_is_held(&tbl->lock))) != NULL) {

  			unsigned int state;

  			write_lock(&n->lock);

  			state = n->nud_state;
  			if (state & (NUD_PERMANENT | NUD_IN_TIMER)) {
  				write_unlock(&n->lock);
  				goto next_elt;
  			}

  			if (time_before(n->used, n->confirmed))
  				n->used = n->confirmed;

  			if (atomic_read(&n->refcnt) == 1 &&
  			    (state == NUD_FAILED ||
  			     time_after(jiffies, n->used + n->parms->gc_staletime))) {
  				*np = n->next;
  				n->dead = 1;
  				write_unlock(&n->lock);
  				neigh_cleanup_and_release(n);
  				continue;
  			}

  			write_unlock(&n->lock);

  
  next_elt:

  			np = &n->next;
  		}
  		/*
  		 * It's fine to release lock here, even if hash table
  		 * grows while we are preempted.
  		 */
  		write_unlock_bh(&tbl->lock);
  		cond_resched();
  		write_lock_bh(&tbl->lock);

  	}

  	/* Cycle through all hash buckets every base_reachable_time/2 ticks.
  	 * ARP entry timeouts range from 1/2 base_reachable_time to 3/2
  	 * base_reachable_time.

  	 */

  	schedule_delayed_work(&tbl->gc_work,
  			      tbl->parms.base_reachable_time >> 1);
  	write_unlock_bh(&tbl->lock);

  }
  
  static __inline__ int neigh_max_probes(struct neighbour *n)
  {
  	struct neigh_parms *p = n->parms;

  	return (n->nud_state & NUD_PROBE) ?

  		p->ucast_probes :

  		p->ucast_probes + p->app_probes + p->mcast_probes;

  }

  static void neigh_invalidate(struct neighbour *neigh)

  	__releases(neigh->lock)
  	__acquires(neigh->lock)

  {
  	struct sk_buff *skb;
  
  	NEIGH_CACHE_STAT_INC(neigh->tbl, res_failed);
  	NEIGH_PRINTK2("neigh %p is failed.
  ", neigh);
  	neigh->updated = jiffies;
  
  	/* It is very thin place. report_unreachable is very complicated
  	   routine. Particularly, it can hit the same neighbour entry!
  
  	   So that, we try to be accurate and avoid dead loop. --ANK
  	 */
  	while (neigh->nud_state == NUD_FAILED &&
  	       (skb = __skb_dequeue(&neigh->arp_queue)) != NULL) {
  		write_unlock(&neigh->lock);
  		neigh->ops->error_report(neigh, skb);
  		write_lock(&neigh->lock);
  	}
  	skb_queue_purge(&neigh->arp_queue);

  	neigh->arp_queue_len_bytes = 0;

  }

  static void neigh_probe(struct neighbour *neigh)
  	__releases(neigh->lock)
  {
  	struct sk_buff *skb = skb_peek(&neigh->arp_queue);
  	/* keep skb alive even if arp_queue overflows */
  	if (skb)
  		skb = skb_copy(skb, GFP_ATOMIC);
  	write_unlock(&neigh->lock);
  	neigh->ops->solicit(neigh, skb);
  	atomic_inc(&neigh->probes);
  	kfree_skb(skb);
  }

  /* Called when a timer expires for a neighbour entry. */
  
  static void neigh_timer_handler(unsigned long arg)
  {
  	unsigned long now, next;
  	struct neighbour *neigh = (struct neighbour *)arg;
  	unsigned state;
  	int notify = 0;
  
  	write_lock(&neigh->lock);
  
  	state = neigh->nud_state;
  	now = jiffies;
  	next = now + HZ;

  	if (!(state & NUD_IN_TIMER))

  		goto out;

  
  	if (state & NUD_REACHABLE) {

  		if (time_before_eq(now,

  				   neigh->confirmed + neigh->parms->reachable_time)) {
  			NEIGH_PRINTK2("neigh %p is still alive.
  ", neigh);
  			next = neigh->confirmed + neigh->parms->reachable_time;
  		} else if (time_before_eq(now,
  					  neigh->used + neigh->parms->delay_probe_time)) {
  			NEIGH_PRINTK2("neigh %p is delayed.
  ", neigh);
  			neigh->nud_state = NUD_DELAY;

  			neigh->updated = jiffies;

  			neigh_suspect(neigh);
  			next = now + neigh->parms->delay_probe_time;
  		} else {
  			NEIGH_PRINTK2("neigh %p is suspected.
  ", neigh);
  			neigh->nud_state = NUD_STALE;

  			neigh->updated = jiffies;

  			neigh_suspect(neigh);

  			notify = 1;

  		}
  	} else if (state & NUD_DELAY) {

  		if (time_before_eq(now,

  				   neigh->confirmed + neigh->parms->delay_probe_time)) {
  			NEIGH_PRINTK2("neigh %p is now reachable.
  ", neigh);
  			neigh->nud_state = NUD_REACHABLE;

  			neigh->updated = jiffies;

  			neigh_connect(neigh);

  			notify = 1;

  			next = neigh->confirmed + neigh->parms->reachable_time;
  		} else {
  			NEIGH_PRINTK2("neigh %p is probed.
  ", neigh);
  			neigh->nud_state = NUD_PROBE;

  			neigh->updated = jiffies;

  			atomic_set(&neigh->probes, 0);
  			next = now + neigh->parms->retrans_time;
  		}
  	} else {
  		/* NUD_PROBE|NUD_INCOMPLETE */
  		next = now + neigh->parms->retrans_time;
  	}
  
  	if ((neigh->nud_state & (NUD_INCOMPLETE | NUD_PROBE)) &&
  	    atomic_read(&neigh->probes) >= neigh_max_probes(neigh)) {

  		neigh->nud_state = NUD_FAILED;
  		notify = 1;

  		neigh_invalidate(neigh);

  	}
  
  	if (neigh->nud_state & NUD_IN_TIMER) {

  		if (time_before(next, jiffies + HZ/2))
  			next = jiffies + HZ/2;

  		if (!mod_timer(&neigh->timer, next))
  			neigh_hold(neigh);

  	}
  	if (neigh->nud_state & (NUD_INCOMPLETE | NUD_PROBE)) {

  		neigh_probe(neigh);

  	} else {

  out:

  		write_unlock(&neigh->lock);
  	}

  	if (notify)

  		neigh_update_notify(neigh);

  	neigh_release(neigh);
  }
  
  int __neigh_event_send(struct neighbour *neigh, struct sk_buff *skb)
  {
  	int rc;

  	bool immediate_probe = false;

  
  	write_lock_bh(&neigh->lock);
  
  	rc = 0;
  	if (neigh->nud_state & (NUD_CONNECTED | NUD_DELAY | NUD_PROBE))
  		goto out_unlock_bh;

  	if (!(neigh->nud_state & (NUD_STALE | NUD_INCOMPLETE))) {
  		if (neigh->parms->mcast_probes + neigh->parms->app_probes) {

  			unsigned long next, now = jiffies;

  			atomic_set(&neigh->probes, neigh->parms->ucast_probes);
  			neigh->nud_state     = NUD_INCOMPLETE;

  			neigh->updated = now;
  			next = now + max(neigh->parms->retrans_time, HZ/2);
  			neigh_add_timer(neigh, next);
  			immediate_probe = true;

  		} else {
  			neigh->nud_state = NUD_FAILED;

  			neigh->updated = jiffies;

  			write_unlock_bh(&neigh->lock);

  			kfree_skb(skb);

  			return 1;
  		}
  	} else if (neigh->nud_state & NUD_STALE) {
  		NEIGH_PRINTK2("neigh %p is delayed.
  ", neigh);

  		neigh->nud_state = NUD_DELAY;

  		neigh->updated = jiffies;

  		neigh_add_timer(neigh,
  				jiffies + neigh->parms->delay_probe_time);

  	}
  
  	if (neigh->nud_state == NUD_INCOMPLETE) {
  		if (skb) {

  			while (neigh->arp_queue_len_bytes + skb->truesize >
  			       neigh->parms->queue_len_bytes) {

  				struct sk_buff *buff;

  				buff = __skb_dequeue(&neigh->arp_queue);

  				if (!buff)
  					break;
  				neigh->arp_queue_len_bytes -= buff->truesize;

  				kfree_skb(buff);

  				NEIGH_CACHE_STAT_INC(neigh->tbl, unres_discards);

  			}

  			skb_dst_force(skb);

  			__skb_queue_tail(&neigh->arp_queue, skb);

  			neigh->arp_queue_len_bytes += skb->truesize;

  		}
  		rc = 1;
  	}
  out_unlock_bh:

  	if (immediate_probe)
  		neigh_probe(neigh);
  	else
  		write_unlock(&neigh->lock);
  	local_bh_enable();

  	return rc;
  }

  EXPORT_SYMBOL(__neigh_event_send);

  static void neigh_update_hhs(struct neighbour *neigh)

  {
  	struct hh_cache *hh;

  	void (*update)(struct hh_cache*, const struct net_device*, const unsigned char *)

  		= NULL;
  
  	if (neigh->dev->header_ops)
  		update = neigh->dev->header_ops->cache_update;

  
  	if (update) {

  		hh = &neigh->hh;
  		if (hh->hh_len) {

  			write_seqlock_bh(&hh->hh_lock);

  			update(hh, neigh->dev, neigh->ha);

  			write_sequnlock_bh(&hh->hh_lock);

  		}
  	}
  }
  
  
  
  /* Generic update routine.
     -- lladdr is new lladdr or NULL, if it is not supplied.
     -- new    is new state.
     -- flags
  	NEIGH_UPDATE_F_OVERRIDE allows to override existing lladdr,
  				if it is different.
  	NEIGH_UPDATE_F_WEAK_OVERRIDE will suspect existing "connected"

  				lladdr instead of overriding it

  				if it is different.
  				It also allows to retain current state
  				if lladdr is unchanged.
  	NEIGH_UPDATE_F_ADMIN	means that the change is administrative.

  	NEIGH_UPDATE_F_OVERRIDE_ISROUTER allows to override existing

  				NTF_ROUTER flag.
  	NEIGH_UPDATE_F_ISROUTER	indicates if the neighbour is known as
  				a router.
  
     Caller MUST hold reference count on the entry.
   */
  
  int neigh_update(struct neighbour *neigh, const u8 *lladdr, u8 new,
  		 u32 flags)
  {
  	u8 old;
  	int err;

  	int notify = 0;

  	struct net_device *dev;
  	int update_isrouter = 0;
  
  	write_lock_bh(&neigh->lock);
  
  	dev    = neigh->dev;
  	old    = neigh->nud_state;
  	err    = -EPERM;

  	if (!(flags & NEIGH_UPDATE_F_ADMIN) &&

  	    (old & (NUD_NOARP | NUD_PERMANENT)))
  		goto out;
  
  	if (!(new & NUD_VALID)) {
  		neigh_del_timer(neigh);
  		if (old & NUD_CONNECTED)
  			neigh_suspect(neigh);
  		neigh->nud_state = new;
  		err = 0;

  		notify = old & NUD_VALID;

  		if ((old & (NUD_INCOMPLETE | NUD_PROBE)) &&
  		    (new & NUD_FAILED)) {
  			neigh_invalidate(neigh);
  			notify = 1;
  		}

  		goto out;
  	}
  
  	/* Compare new lladdr with cached one */
  	if (!dev->addr_len) {
  		/* First case: device needs no address. */
  		lladdr = neigh->ha;
  	} else if (lladdr) {
  		/* The second case: if something is already cached
  		   and a new address is proposed:
  		   - compare new & old
  		   - if they are different, check override flag
  		 */

  		if ((old & NUD_VALID) &&

  		    !memcmp(lladdr, neigh->ha, dev->addr_len))
  			lladdr = neigh->ha;
  	} else {
  		/* No address is supplied; if we know something,
  		   use it, otherwise discard the request.
  		 */
  		err = -EINVAL;
  		if (!(old & NUD_VALID))
  			goto out;
  		lladdr = neigh->ha;
  	}
  
  	if (new & NUD_CONNECTED)
  		neigh->confirmed = jiffies;
  	neigh->updated = jiffies;
  
  	/* If entry was valid and address is not changed,
  	   do not change entry state, if new one is STALE.
  	 */
  	err = 0;
  	update_isrouter = flags & NEIGH_UPDATE_F_OVERRIDE_ISROUTER;
  	if (old & NUD_VALID) {
  		if (lladdr != neigh->ha && !(flags & NEIGH_UPDATE_F_OVERRIDE)) {
  			update_isrouter = 0;
  			if ((flags & NEIGH_UPDATE_F_WEAK_OVERRIDE) &&
  			    (old & NUD_CONNECTED)) {
  				lladdr = neigh->ha;
  				new = NUD_STALE;
  			} else
  				goto out;
  		} else {
  			if (lladdr == neigh->ha && new == NUD_STALE &&
  			    ((flags & NEIGH_UPDATE_F_WEAK_OVERRIDE) ||
  			     (old & NUD_CONNECTED))
  			    )
  				new = old;
  		}
  	}
  
  	if (new != old) {
  		neigh_del_timer(neigh);

  		if (new & NUD_IN_TIMER)

  			neigh_add_timer(neigh, (jiffies +
  						((new & NUD_REACHABLE) ?

  						 neigh->parms->reachable_time :
  						 0)));

  		neigh->nud_state = new;
  	}
  
  	if (lladdr != neigh->ha) {

  		write_seqlock(&neigh->ha_lock);

  		memcpy(&neigh->ha, lladdr, dev->addr_len);

  		write_sequnlock(&neigh->ha_lock);

  		neigh_update_hhs(neigh);
  		if (!(new & NUD_CONNECTED))
  			neigh->confirmed = jiffies -
  				      (neigh->parms->base_reachable_time << 1);

  		notify = 1;

  	}
  	if (new == old)
  		goto out;
  	if (new & NUD_CONNECTED)
  		neigh_connect(neigh);
  	else
  		neigh_suspect(neigh);
  	if (!(old & NUD_VALID)) {
  		struct sk_buff *skb;
  
  		/* Again: avoid dead loop if something went wrong */
  
  		while (neigh->nud_state & NUD_VALID &&
  		       (skb = __skb_dequeue(&neigh->arp_queue)) != NULL) {

  			struct dst_entry *dst = skb_dst(skb);
  			struct neighbour *n2, *n1 = neigh;

  			write_unlock_bh(&neigh->lock);

  
  			rcu_read_lock();

  			/* On shaper/eql skb->dst->neighbour != neigh :( */

  			if (dst && (n2 = dst_get_neighbour_noref(dst)) != NULL)

  				n1 = n2;

  			n1->output(n1, skb);

  			rcu_read_unlock();

  			write_lock_bh(&neigh->lock);
  		}
  		skb_queue_purge(&neigh->arp_queue);

  		neigh->arp_queue_len_bytes = 0;

  	}
  out:
  	if (update_isrouter) {
  		neigh->flags = (flags & NEIGH_UPDATE_F_ISROUTER) ?
  			(neigh->flags | NTF_ROUTER) :
  			(neigh->flags & ~NTF_ROUTER);
  	}
  	write_unlock_bh(&neigh->lock);

  
  	if (notify)

  		neigh_update_notify(neigh);

  	return err;
  }

  EXPORT_SYMBOL(neigh_update);

  
  struct neighbour *neigh_event_ns(struct neigh_table *tbl,
  				 u8 *lladdr, void *saddr,
  				 struct net_device *dev)
  {
  	struct neighbour *neigh = __neigh_lookup(tbl, saddr, dev,
  						 lladdr || !dev->addr_len);
  	if (neigh)

  		neigh_update(neigh, lladdr, NUD_STALE,

  			     NEIGH_UPDATE_F_OVERRIDE);
  	return neigh;
  }

  EXPORT_SYMBOL(neigh_event_ns);

  /* called with read_lock_bh(&n->lock); */

  static void neigh_hh_init(struct neighbour *n, struct dst_entry *dst)

  {

  	struct net_device *dev = dst->dev;

  	__be16 prot = dst->ops->protocol;
  	struct hh_cache	*hh = &n->hh;

  
  	write_lock_bh(&n->lock);

  	/* Only one thread can come in here and initialize the
  	 * hh_cache entry.
  	 */

  	if (!hh->hh_len)
  		dev->header_ops->cache(n, hh, prot);

  	write_unlock_bh(&n->lock);

  }
  
  /* This function can be used in contexts, where only old dev_queue_xmit

   * worked, f.e. if you want to override normal output path (eql, shaper),
   * but resolution is not made yet.

   */

  int neigh_compat_output(struct neighbour *neigh, struct sk_buff *skb)

  {
  	struct net_device *dev = skb->dev;

  	__skb_pull(skb, skb_network_offset(skb));

  	if (dev_hard_header(skb, dev, ntohs(skb->protocol), NULL, NULL,
  			    skb->len) < 0 &&

  	    dev->header_ops->rebuild(skb))

  		return 0;
  
  	return dev_queue_xmit(skb);
  }

  EXPORT_SYMBOL(neigh_compat_output);

  
  /* Slow and careful. */

  int neigh_resolve_output(struct neighbour *neigh, struct sk_buff *skb)

  {

  	struct dst_entry *dst = skb_dst(skb);

  	int rc = 0;

  	if (!dst)

  		goto discard;

  	__skb_pull(skb, skb_network_offset(skb));

  
  	if (!neigh_event_send(neigh, skb)) {
  		int err;
  		struct net_device *dev = neigh->dev;

  		unsigned int seq;

  		if (dev->header_ops->cache && !neigh->hh.hh_len)
  			neigh_hh_init(neigh, dst);

  		do {
  			seq = read_seqbegin(&neigh->ha_lock);
  			err = dev_hard_header(skb, dev, ntohs(skb->protocol),
  					      neigh->ha, NULL, skb->len);
  		} while (read_seqretry(&neigh->ha_lock, seq));

  		if (err >= 0)

  			rc = dev_queue_xmit(skb);

  		else
  			goto out_kfree_skb;
  	}
  out:
  	return rc;
  discard:
  	NEIGH_PRINTK1("neigh_resolve_output: dst=%p neigh=%p
  ",

  		      dst, neigh);

  out_kfree_skb:
  	rc = -EINVAL;
  	kfree_skb(skb);
  	goto out;
  }

  EXPORT_SYMBOL(neigh_resolve_output);

  
  /* As fast as possible without hh cache */

  int neigh_connected_output(struct neighbour *neigh, struct sk_buff *skb)

  {

  	struct net_device *dev = neigh->dev;

  	unsigned int seq;

  	int err;

  	__skb_pull(skb, skb_network_offset(skb));

  	do {
  		seq = read_seqbegin(&neigh->ha_lock);
  		err = dev_hard_header(skb, dev, ntohs(skb->protocol),
  				      neigh->ha, NULL, skb->len);
  	} while (read_seqretry(&neigh->ha_lock, seq));

  	if (err >= 0)

  		err = dev_queue_xmit(skb);

  	else {
  		err = -EINVAL;
  		kfree_skb(skb);
  	}
  	return err;
  }

  EXPORT_SYMBOL(neigh_connected_output);

  int neigh_direct_output(struct neighbour *neigh, struct sk_buff *skb)
  {
  	return dev_queue_xmit(skb);
  }
  EXPORT_SYMBOL(neigh_direct_output);

  static void neigh_proxy_process(unsigned long arg)
  {
  	struct neigh_table *tbl = (struct neigh_table *)arg;
  	long sched_next = 0;
  	unsigned long now = jiffies;

  	struct sk_buff *skb, *n;

  
  	spin_lock(&tbl->proxy_queue.lock);

  	skb_queue_walk_safe(&tbl->proxy_queue, skb, n) {
  		long tdif = NEIGH_CB(skb)->sched_next - now;

  		if (tdif <= 0) {

  			struct net_device *dev = skb->dev;

  			__skb_unlink(skb, &tbl->proxy_queue);

  			if (tbl->proxy_redo && netif_running(dev)) {
  				rcu_read_lock();

  				tbl->proxy_redo(skb);

  				rcu_read_unlock();
  			} else {

  				kfree_skb(skb);

  			}

  
  			dev_put(dev);
  		} else if (!sched_next || tdif < sched_next)
  			sched_next = tdif;
  	}
  	del_timer(&tbl->proxy_timer);
  	if (sched_next)
  		mod_timer(&tbl->proxy_timer, jiffies + sched_next);
  	spin_unlock(&tbl->proxy_queue.lock);
  }
  
  void pneigh_enqueue(struct neigh_table *tbl, struct neigh_parms *p,
  		    struct sk_buff *skb)
  {
  	unsigned long now = jiffies;
  	unsigned long sched_next = now + (net_random() % p->proxy_delay);
  
  	if (tbl->proxy_queue.qlen > p->proxy_qlen) {
  		kfree_skb(skb);
  		return;
  	}

  
  	NEIGH_CB(skb)->sched_next = sched_next;
  	NEIGH_CB(skb)->flags |= LOCALLY_ENQUEUED;

  
  	spin_lock(&tbl->proxy_queue.lock);
  	if (del_timer(&tbl->proxy_timer)) {
  		if (time_before(tbl->proxy_timer.expires, sched_next))
  			sched_next = tbl->proxy_timer.expires;
  	}

  	skb_dst_drop(skb);

  	dev_hold(skb->dev);
  	__skb_queue_tail(&tbl->proxy_queue, skb);
  	mod_timer(&tbl->proxy_timer, sched_next);
  	spin_unlock(&tbl->proxy_queue.lock);
  }

  EXPORT_SYMBOL(pneigh_enqueue);

  static inline struct neigh_parms *lookup_neigh_parms(struct neigh_table *tbl,

  						      struct net *net, int ifindex)
  {
  	struct neigh_parms *p;
  
  	for (p = &tbl->parms; p; p = p->next) {

  		if ((p->dev && p->dev->ifindex == ifindex && net_eq(neigh_parms_net(p), net)) ||

  		    (!p->dev && !ifindex))
  			return p;
  	}
  
  	return NULL;
  }

  
  struct neigh_parms *neigh_parms_alloc(struct net_device *dev,
  				      struct neigh_table *tbl)
  {

  	struct neigh_parms *p, *ref;

  	struct net *net = dev_net(dev);
  	const struct net_device_ops *ops = dev->netdev_ops;

  	ref = lookup_neigh_parms(tbl, net, 0);

  	if (!ref)
  		return NULL;

  	p = kmemdup(ref, sizeof(*p), GFP_KERNEL);

  	if (p) {

  		p->tbl		  = tbl;
  		atomic_set(&p->refcnt, 1);

  		p->reachable_time =
  				neigh_rand_reach_time(p->base_reachable_time);

  		if (ops->ndo_neigh_setup && ops->ndo_neigh_setup(dev, p)) {

  			kfree(p);
  			return NULL;

  		}

  
  		dev_hold(dev);
  		p->dev = dev;

  		write_pnet(&p->net, hold_net(net));

  		p->sysctl_table = NULL;
  		write_lock_bh(&tbl->lock);
  		p->next		= tbl->parms.next;
  		tbl->parms.next = p;
  		write_unlock_bh(&tbl->lock);
  	}
  	return p;
  }

  EXPORT_SYMBOL(neigh_parms_alloc);

  
  static void neigh_rcu_free_parms(struct rcu_head *head)
  {
  	struct neigh_parms *parms =
  		container_of(head, struct neigh_parms, rcu_head);
  
  	neigh_parms_put(parms);
  }
  
  void neigh_parms_release(struct neigh_table *tbl, struct neigh_parms *parms)
  {
  	struct neigh_parms **p;
  
  	if (!parms || parms == &tbl->parms)
  		return;
  	write_lock_bh(&tbl->lock);
  	for (p = &tbl->parms.next; *p; p = &(*p)->next) {
  		if (*p == parms) {
  			*p = parms->next;
  			parms->dead = 1;
  			write_unlock_bh(&tbl->lock);

  			if (parms->dev)
  				dev_put(parms->dev);

  			call_rcu(&parms->rcu_head, neigh_rcu_free_parms);
  			return;
  		}
  	}
  	write_unlock_bh(&tbl->lock);
  	NEIGH_PRINTK1("neigh_parms_release: not found
  ");
  }

  EXPORT_SYMBOL(neigh_parms_release);

  static void neigh_parms_destroy(struct neigh_parms *parms)

  {

  	release_net(neigh_parms_net(parms));

  	kfree(parms);
  }

  static struct lock_class_key neigh_table_proxy_queue_class;

  void neigh_table_init_no_netlink(struct neigh_table *tbl)

  {
  	unsigned long now = jiffies;
  	unsigned long phsize;

  	write_pnet(&tbl->parms.net, &init_net);

  	atomic_set(&tbl->parms.refcnt, 1);

  	tbl->parms.reachable_time =
  			  neigh_rand_reach_time(tbl->parms.base_reachable_time);

  	tbl->stats = alloc_percpu(struct neigh_statistics);
  	if (!tbl->stats)
  		panic("cannot create neighbour cache statistics");

  #ifdef CONFIG_PROC_FS

  	if (!proc_create_data(tbl->id, 0, init_net.proc_net_stat,
  			      &neigh_stat_seq_fops, tbl))

  		panic("cannot create neighbour proc dir entry");

  #endif

  	RCU_INIT_POINTER(tbl->nht, neigh_hash_alloc(3));

  
  	phsize = (PNEIGH_HASHMASK + 1) * sizeof(struct pneigh_entry *);

  	tbl->phash_buckets = kzalloc(phsize, GFP_KERNEL);

  	if (!tbl->nht || !tbl->phash_buckets)

  		panic("cannot allocate neighbour cache hashes");

  	rwlock_init(&tbl->lock);

  	INIT_DELAYED_WORK_DEFERRABLE(&tbl->gc_work, neigh_periodic_work);
  	schedule_delayed_work(&tbl->gc_work, tbl->parms.reachable_time);

  	setup_timer(&tbl->proxy_timer, neigh_proxy_process, (unsigned long)tbl);

  	skb_queue_head_init_class(&tbl->proxy_queue,
  			&neigh_table_proxy_queue_class);

  
  	tbl->last_flush = now;
  	tbl->last_rand	= now + tbl->parms.reachable_time * 20;

  }

  EXPORT_SYMBOL(neigh_table_init_no_netlink);

  
  void neigh_table_init(struct neigh_table *tbl)
  {
  	struct neigh_table *tmp;
  
  	neigh_table_init_no_netlink(tbl);

  	write_lock(&neigh_tbl_lock);

  	for (tmp = neigh_tables; tmp; tmp = tmp->next) {
  		if (tmp->family == tbl->family)
  			break;
  	}

  	tbl->next	= neigh_tables;
  	neigh_tables	= tbl;
  	write_unlock(&neigh_tbl_lock);

  
  	if (unlikely(tmp)) {
  		printk(KERN_ERR "NEIGH: Registering multiple tables for "
  		       "family %d
  ", tbl->family);
  		dump_stack();
  	}

  }

  EXPORT_SYMBOL(neigh_table_init);

  
  int neigh_table_clear(struct neigh_table *tbl)
  {
  	struct neigh_table **tp;
  
  	/* It is not clean... Fix it to unload IPv6 module safely */

  	cancel_delayed_work_sync(&tbl->gc_work);

  	del_timer_sync(&tbl->proxy_timer);
  	pneigh_queue_purge(&tbl->proxy_queue);
  	neigh_ifdown(tbl, NULL);
  	if (atomic_read(&tbl->entries))
  		printk(KERN_CRIT "neighbour leakage
  ");
  	write_lock(&neigh_tbl_lock);
  	for (tp = &neigh_tables; *tp; tp = &(*tp)->next) {
  		if (*tp == tbl) {
  			*tp = tbl->next;
  			break;
  		}
  	}
  	write_unlock(&neigh_tbl_lock);

  	call_rcu(&rcu_dereference_protected(tbl->nht, 1)->rcu,
  		 neigh_hash_free_rcu);

  	tbl->nht = NULL;

  
  	kfree(tbl->phash_buckets);
  	tbl->phash_buckets = NULL;

  	remove_proc_entry(tbl->id, init_net.proc_net_stat);

  	free_percpu(tbl->stats);
  	tbl->stats = NULL;

  	return 0;
  }

  EXPORT_SYMBOL(neigh_table_clear);

  static int neigh_delete(struct sk_buff *skb, struct nlmsghdr *nlh, void *arg)

  {

  	struct net *net = sock_net(skb->sk);

  	struct ndmsg *ndm;
  	struct nlattr *dst_attr;

  	struct neigh_table *tbl;
  	struct net_device *dev = NULL;

  	int err = -EINVAL;

  	ASSERT_RTNL();

  	if (nlmsg_len(nlh) < sizeof(*ndm))

  		goto out;

  	dst_attr = nlmsg_find_attr(nlh, sizeof(*ndm), NDA_DST);
  	if (dst_attr == NULL)
  		goto out;
  
  	ndm = nlmsg_data(nlh);
  	if (ndm->ndm_ifindex) {

  		dev = __dev_get_by_index(net, ndm->ndm_ifindex);

  		if (dev == NULL) {
  			err = -ENODEV;
  			goto out;
  		}
  	}

  	read_lock(&neigh_tbl_lock);
  	for (tbl = neigh_tables; tbl; tbl = tbl->next) {

  		struct neighbour *neigh;

  
  		if (tbl->family != ndm->ndm_family)
  			continue;
  		read_unlock(&neigh_tbl_lock);

  		if (nla_len(dst_attr) < tbl->key_len)

  			goto out;

  
  		if (ndm->ndm_flags & NTF_PROXY) {

  			err = pneigh_delete(tbl, net, nla_data(dst_attr), dev);

  			goto out;

  		}

  		if (dev == NULL)

  			goto out;

  		neigh = neigh_lookup(tbl, nla_data(dst_attr), dev);
  		if (neigh == NULL) {
  			err = -ENOENT;

  			goto out;

  		}

  
  		err = neigh_update(neigh, NULL, NUD_FAILED,
  				   NEIGH_UPDATE_F_OVERRIDE |
  				   NEIGH_UPDATE_F_ADMIN);
  		neigh_release(neigh);

  		goto out;

  	}
  	read_unlock(&neigh_tbl_lock);

  	err = -EAFNOSUPPORT;

  out:
  	return err;
  }

  static int neigh_add(struct sk_buff *skb, struct nlmsghdr *nlh, void *arg)

  {

  	struct net *net = sock_net(skb->sk);

  	struct ndmsg *ndm;
  	struct nlattr *tb[NDA_MAX+1];

  	struct neigh_table *tbl;
  	struct net_device *dev = NULL;

  	int err;

  	ASSERT_RTNL();

  	err = nlmsg_parse(nlh, sizeof(*ndm), tb, NDA_MAX, NULL);
  	if (err < 0)

  		goto out;

  	err = -EINVAL;
  	if (tb[NDA_DST] == NULL)
  		goto out;
  
  	ndm = nlmsg_data(nlh);
  	if (ndm->ndm_ifindex) {

  		dev = __dev_get_by_index(net, ndm->ndm_ifindex);

  		if (dev == NULL) {
  			err = -ENODEV;
  			goto out;
  		}
  
  		if (tb[NDA_LLADDR] && nla_len(tb[NDA_LLADDR]) < dev->addr_len)

  			goto out;

  	}

  	read_lock(&neigh_tbl_lock);
  	for (tbl = neigh_tables; tbl; tbl = tbl->next) {

  		int flags = NEIGH_UPDATE_F_ADMIN | NEIGH_UPDATE_F_OVERRIDE;
  		struct neighbour *neigh;
  		void *dst, *lladdr;

  
  		if (tbl->family != ndm->ndm_family)
  			continue;
  		read_unlock(&neigh_tbl_lock);

  		if (nla_len(tb[NDA_DST]) < tbl->key_len)

  			goto out;

  		dst = nla_data(tb[NDA_DST]);
  		lladdr = tb[NDA_LLADDR] ? nla_data(tb[NDA_LLADDR]) : NULL;

  
  		if (ndm->ndm_flags & NTF_PROXY) {

  			struct pneigh_entry *pn;
  
  			err = -ENOBUFS;

  			pn = pneigh_lookup(tbl, net, dst, dev, 1);

  			if (pn) {
  				pn->flags = ndm->ndm_flags;
  				err = 0;
  			}

  			goto out;

  		}

  		if (dev == NULL)

  			goto out;

  
  		neigh = neigh_lookup(tbl, dst, dev);
  		if (neigh == NULL) {
  			if (!(nlh->nlmsg_flags & NLM_F_CREATE)) {
  				err = -ENOENT;

  				goto out;

  			}

  			neigh = __neigh_lookup_errno(tbl, dst, dev);
  			if (IS_ERR(neigh)) {
  				err = PTR_ERR(neigh);

  				goto out;

  			}

  		} else {

  			if (nlh->nlmsg_flags & NLM_F_EXCL) {
  				err = -EEXIST;
  				neigh_release(neigh);

  				goto out;

  			}

  			if (!(nlh->nlmsg_flags & NLM_F_REPLACE))
  				flags &= ~NEIGH_UPDATE_F_OVERRIDE;
  		}

  		if (ndm->ndm_flags & NTF_USE) {
  			neigh_event_send(neigh, NULL);
  			err = 0;
  		} else
  			err = neigh_update(neigh, lladdr, ndm->ndm_state, flags);

  		neigh_release(neigh);

  		goto out;

  	}
  
  	read_unlock(&neigh_tbl_lock);

  	err = -EAFNOSUPPORT;

  out:
  	return err;
  }

  static int neightbl_fill_parms(struct sk_buff *skb, struct neigh_parms *parms)
  {

  	struct nlattr *nest;
  
  	nest = nla_nest_start(skb, NDTA_PARMS);
  	if (nest == NULL)
  		return -ENOBUFS;

  
  	if (parms->dev)

  		NLA_PUT_U32(skb, NDTPA_IFINDEX, parms->dev->ifindex);
  
  	NLA_PUT_U32(skb, NDTPA_REFCNT, atomic_read(&parms->refcnt));

  	NLA_PUT_U32(skb, NDTPA_QUEUE_LENBYTES, parms->queue_len_bytes);
  	/* approximative value for deprecated QUEUE_LEN (in packets) */
  	NLA_PUT_U32(skb, NDTPA_QUEUE_LEN,
  		    DIV_ROUND_UP(parms->queue_len_bytes,
  				 SKB_TRUESIZE(ETH_FRAME_LEN)));

  	NLA_PUT_U32(skb, NDTPA_PROXY_QLEN, parms->proxy_qlen);
  	NLA_PUT_U32(skb, NDTPA_APP_PROBES, parms->app_probes);
  	NLA_PUT_U32(skb, NDTPA_UCAST_PROBES, parms->ucast_probes);
  	NLA_PUT_U32(skb, NDTPA_MCAST_PROBES, parms->mcast_probes);
  	NLA_PUT_MSECS(skb, NDTPA_REACHABLE_TIME, parms->reachable_time);
  	NLA_PUT_MSECS(skb, NDTPA_BASE_REACHABLE_TIME,

  		      parms->base_reachable_time);

  	NLA_PUT_MSECS(skb, NDTPA_GC_STALETIME, parms->gc_staletime);
  	NLA_PUT_MSECS(skb, NDTPA_DELAY_PROBE_TIME, parms->delay_probe_time);
  	NLA_PUT_MSECS(skb, NDTPA_RETRANS_TIME, parms->retrans_time);
  	NLA_PUT_MSECS(skb, NDTPA_ANYCAST_DELAY, parms->anycast_delay);
  	NLA_PUT_MSECS(skb, NDTPA_PROXY_DELAY, parms->proxy_delay);
  	NLA_PUT_MSECS(skb, NDTPA_LOCKTIME, parms->locktime);

  	return nla_nest_end(skb, nest);

  nla_put_failure:

  	nla_nest_cancel(skb, nest);
  	return -EMSGSIZE;

  }

  static int neightbl_fill_info(struct sk_buff *skb, struct neigh_table *tbl,
  			      u32 pid, u32 seq, int type, int flags)

  {
  	struct nlmsghdr *nlh;
  	struct ndtmsg *ndtmsg;

  	nlh = nlmsg_put(skb, pid, seq, type, sizeof(*ndtmsg), flags);
  	if (nlh == NULL)

  		return -EMSGSIZE;

  	ndtmsg = nlmsg_data(nlh);

  
  	read_lock_bh(&tbl->lock);
  	ndtmsg->ndtm_family = tbl->family;

  	ndtmsg->ndtm_pad1   = 0;
  	ndtmsg->ndtm_pad2   = 0;