net/bridge/br_fdb.c - kernel/msm - Gitiles

 /*
  *	Forwarding database
  *	Linux ethernet bridge
  *
  *	Authors:
  *	Lennert Buytenhek		<buytenh@gnu.org>
  *
  *	$Id: br_fdb.c,v 1.6 2002/01/17 00:57:07 davem Exp $
  *
  *	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.
  */

 #include <linux/kernel.h>
 #include <linux/init.h>
 #include <linux/spinlock.h>
 #include <linux/times.h>
 #include <linux/netdevice.h>
 #include <linux/etherdevice.h>
 #include <linux/jhash.h>
 #include <linux/random.h>
 #include <asm/atomic.h>
 #include <asm/unaligned.h>
 #include "br_private.h"

 static struct kmem_cache *br_fdb_cache __read_mostly;
 static int fdb_insert(struct net_bridge *br, struct net_bridge_port *source,
 		      const unsigned char *addr);

 static u32 fdb_salt __read_mostly;

 int __init br_fdb_init(void)
 {
 	br_fdb_cache = kmem_cache_create("bridge_fdb_cache",
 					 sizeof(struct net_bridge_fdb_entry),
 					 0,
 					 SLAB_HWCACHE_ALIGN, NULL);
 	if (!br_fdb_cache)
 		return -ENOMEM;

 	get_random_bytes(&fdb_salt, sizeof(fdb_salt));
 	return 0;
 }

 void __exit br_fdb_fini(void)
 {
 	kmem_cache_destroy(br_fdb_cache);
 }


 /* if topology_changing then use forward_delay (default 15 sec)
  * otherwise keep longer (default 5 minutes)
  */
 static inline unsigned long hold_time(const struct net_bridge *br)
 {
 	return br->topology_change ? br->forward_delay : br->ageing_time;
 }

 static inline int has_expired(const struct net_bridge *br,
 				  const struct net_bridge_fdb_entry *fdb)
 {
 	return !fdb->is_static
 		&& time_before_eq(fdb->ageing_timer + hold_time(br), jiffies);
 }

 static inline int br_mac_hash(const unsigned char *mac)
 {
 	/* use 1 byte of OUI cnd 3 bytes of NIC */
 	u32 key = get_unaligned((u32 *)(mac + 2));
 	return jhash_1word(key, fdb_salt) & (BR_HASH_SIZE - 1);
 }

 static inline void fdb_delete(struct net_bridge_fdb_entry *f)
 {
 	hlist_del_rcu(&f->hlist);
 	br_fdb_put(f);
 }

 void br_fdb_changeaddr(struct net_bridge_port *p, const unsigned char *newaddr)
 {
 	struct net_bridge *br = p->br;
 	int i;

 	spin_lock_bh(&br->hash_lock);

 	/* Search all chains since old address/hash is unknown */
 	for (i = 0; i < BR_HASH_SIZE; i++) {
 		struct hlist_node *h;
 		hlist_for_each(h, &br->hash[i]) {
 			struct net_bridge_fdb_entry *f;

 			f = hlist_entry(h, struct net_bridge_fdb_entry, hlist);
 			if (f->dst == p && f->is_local) {
 				/* maybe another port has same hw addr? */
 				struct net_bridge_port *op;
 				list_for_each_entry(op, &br->port_list, list) {
 					if (op != p &&
 					    !compare_ether_addr(op->dev->dev_addr,
 								f->addr.addr)) {
 						f->dst = op;
 						goto insert;
 					}
 				}

 				/* delete old one */
 				fdb_delete(f);
 				goto insert;
 			}
 		}
 	}
  insert:
 	/* insert new address,  may fail if invalid address or dup. */
 	fdb_insert(br, p, newaddr);

 	spin_unlock_bh(&br->hash_lock);
 }

 void br_fdb_cleanup(unsigned long _data)
 {
 	struct net_bridge *br = (struct net_bridge *)_data;
 	unsigned long delay = hold_time(br);
 	unsigned long next_timer = jiffies + br->forward_delay;
 	int i;

 	spin_lock_bh(&br->hash_lock);
 	for (i = 0; i < BR_HASH_SIZE; i++) {
 		struct net_bridge_fdb_entry *f;
 		struct hlist_node *h, *n;

 		hlist_for_each_entry_safe(f, h, n, &br->hash[i], hlist) {
 			unsigned long this_timer;
 			if (f->is_static)
 				continue;
 			this_timer = f->ageing_timer + delay;
 			if (time_before_eq(this_timer, jiffies))
 				fdb_delete(f);
 			else if (this_timer < next_timer)
 				next_timer = this_timer;
 		}
 	}
 	spin_unlock_bh(&br->hash_lock);

 	/* Add HZ/4 to ensure we round the jiffies upwards to be after the next
 	 * timer, otherwise we might round down and will have no-op run. */
 	mod_timer(&br->gc_timer, round_jiffies(next_timer + HZ/4));
 }

 /* Completely flush all dynamic entries in forwarding database.*/
 void br_fdb_flush(struct net_bridge *br)
 {
 	int i;

 	spin_lock_bh(&br->hash_lock);
 	for (i = 0; i < BR_HASH_SIZE; i++) {
 		struct net_bridge_fdb_entry *f;
 		struct hlist_node *h, *n;
 		hlist_for_each_entry_safe(f, h, n, &br->hash[i], hlist) {
 			if (!f->is_static)
 				fdb_delete(f);
 		}
 	}
 	spin_unlock_bh(&br->hash_lock);
 }

 /* Flush all entries refering to a specific port.
  * if do_all is set also flush static entries
  */
 void br_fdb_delete_by_port(struct net_bridge *br,
 			   const struct net_bridge_port *p,
 			   int do_all)
 {
 	int i;

 	spin_lock_bh(&br->hash_lock);
 	for (i = 0; i < BR_HASH_SIZE; i++) {
 		struct hlist_node *h, *g;

 		hlist_for_each_safe(h, g, &br->hash[i]) {
 			struct net_bridge_fdb_entry *f
 				= hlist_entry(h, struct net_bridge_fdb_entry, hlist);
 			if (f->dst != p)
 				continue;

 			if (f->is_static && !do_all)
 				continue;
 			/*
 			 * if multiple ports all have the same device address
 			 * then when one port is deleted, assign
 			 * the local entry to other port
 			 */
 			if (f->is_local) {
 				struct net_bridge_port *op;
 				list_for_each_entry(op, &br->port_list, list) {
 					if (op != p &&
 					    !compare_ether_addr(op->dev->dev_addr,
 								f->addr.addr)) {
 						f->dst = op;
 						goto skip_delete;
 					}
 				}
 			}

 			fdb_delete(f);
 		skip_delete: ;
 		}
 	}
 	spin_unlock_bh(&br->hash_lock);
 }

 /* No locking or refcounting, assumes caller has no preempt (rcu_read_lock) */
 struct net_bridge_fdb_entry *__br_fdb_get(struct net_bridge *br,
 					  const unsigned char *addr)
 {
 	struct hlist_node *h;
 	struct net_bridge_fdb_entry *fdb;

 	hlist_for_each_entry_rcu(fdb, h, &br->hash[br_mac_hash(addr)], hlist) {
 		if (!compare_ether_addr(fdb->addr.addr, addr)) {
 			if (unlikely(has_expired(br, fdb)))
 				break;
 			return fdb;
 		}
 	}

 	return NULL;
 }

 /* Interface used by ATM hook that keeps a ref count */
 struct net_bridge_fdb_entry *br_fdb_get(struct net_bridge *br,
 					unsigned char *addr)
 {
 	struct net_bridge_fdb_entry *fdb;

 	rcu_read_lock();
 	fdb = __br_fdb_get(br, addr);
 	if (fdb && !atomic_inc_not_zero(&fdb->use_count))
 		fdb = NULL;
 	rcu_read_unlock();
 	return fdb;
 }

 static void fdb_rcu_free(struct rcu_head *head)
 {
 	struct net_bridge_fdb_entry *ent
 		= container_of(head, struct net_bridge_fdb_entry, rcu);
 	kmem_cache_free(br_fdb_cache, ent);
 }

 /* Set entry up for deletion with RCU  */
 void br_fdb_put(struct net_bridge_fdb_entry *ent)
 {
 	if (atomic_dec_and_test(&ent->use_count))
 		call_rcu(&ent->rcu, fdb_rcu_free);
 }

 /*
  * Fill buffer with forwarding table records in
  * the API format.
  */
 int br_fdb_fillbuf(struct net_bridge *br, void *buf,
 		   unsigned long maxnum, unsigned long skip)
 {
 	struct __fdb_entry *fe = buf;
 	int i, num = 0;
 	struct hlist_node *h;
 	struct net_bridge_fdb_entry *f;

 	memset(buf, 0, maxnum*sizeof(struct __fdb_entry));

 	rcu_read_lock();
 	for (i = 0; i < BR_HASH_SIZE; i++) {
 		hlist_for_each_entry_rcu(f, h, &br->hash[i], hlist) {
 			if (num >= maxnum)
 				goto out;

 			if (has_expired(br, f))
 				continue;

 			if (skip) {
 				--skip;
 				continue;
 			}

 			/* convert from internal format to API */
 			memcpy(fe->mac_addr, f->addr.addr, ETH_ALEN);
 			fe->port_no = f->dst->port_no;
 			fe->is_local = f->is_local;
 			if (!f->is_static)
 				fe->ageing_timer_value = jiffies_to_clock_t(jiffies - f->ageing_timer);
 			++fe;
 			++num;
 		}
 	}

  out:
 	rcu_read_unlock();

 	return num;
 }

 static inline struct net_bridge_fdb_entry *fdb_find(struct hlist_head *head,
 						    const unsigned char *addr)
 {
 	struct hlist_node *h;
 	struct net_bridge_fdb_entry *fdb;

 	hlist_for_each_entry_rcu(fdb, h, head, hlist) {
 		if (!compare_ether_addr(fdb->addr.addr, addr))
 			return fdb;
 	}
 	return NULL;
 }

 static struct net_bridge_fdb_entry *fdb_create(struct hlist_head *head,
 					       struct net_bridge_port *source,
 					       const unsigned char *addr,
 					       int is_local)
 {
 	struct net_bridge_fdb_entry *fdb;

 	fdb = kmem_cache_alloc(br_fdb_cache, GFP_ATOMIC);
 	if (fdb) {
 		memcpy(fdb->addr.addr, addr, ETH_ALEN);
 		atomic_set(&fdb->use_count, 1);
 		hlist_add_head_rcu(&fdb->hlist, head);

 		fdb->dst = source;
 		fdb->is_local = is_local;
 		fdb->is_static = is_local;
 		fdb->ageing_timer = jiffies;
 	}
 	return fdb;
 }

 static int fdb_insert(struct net_bridge *br, struct net_bridge_port *source,
 		  const unsigned char *addr)
 {
 	struct hlist_head *head = &br->hash[br_mac_hash(addr)];
 	struct net_bridge_fdb_entry *fdb;

 	if (!is_valid_ether_addr(addr))
 		return -EINVAL;

 	fdb = fdb_find(head, addr);
 	if (fdb) {
 		/* it is okay to have multiple ports with same
 		 * address, just use the first one.
 		 */
 		if (fdb->is_local)
 			return 0;

 		printk(KERN_WARNING "%s adding interface with same address "
 		       "as a received packet\n",
 		       source->dev->name);
 		fdb_delete(fdb);
 	}

 	if (!fdb_create(head, source, addr, 1))
 		return -ENOMEM;

 	return 0;
 }

 int br_fdb_insert(struct net_bridge *br, struct net_bridge_port *source,
 		  const unsigned char *addr)
 {
 	int ret;

 	spin_lock_bh(&br->hash_lock);
 	ret = fdb_insert(br, source, addr);
 	spin_unlock_bh(&br->hash_lock);
 	return ret;
 }

 void br_fdb_update(struct net_bridge *br, struct net_bridge_port *source,
 		   const unsigned char *addr)
 {
 	struct hlist_head *head = &br->hash[br_mac_hash(addr)];
 	struct net_bridge_fdb_entry *fdb;

 	/* some users want to always flood. */
 	if (hold_time(br) == 0)
 		return;

 	fdb = fdb_find(head, addr);
 	if (likely(fdb)) {
 		/* attempt to update an entry for a local interface */
 		if (unlikely(fdb->is_local)) {
 			if (net_ratelimit())
 				printk(KERN_WARNING "%s: received packet with "
 				       " own address as source address\n",
 				       source->dev->name);
 		} else {
 			/* fastpath: update of existing entry */
 			fdb->dst = source;
 			fdb->ageing_timer = jiffies;
 		}
 	} else {
 		spin_lock(&br->hash_lock);
 		if (!fdb_find(head, addr))
 			fdb_create(head, source, addr, 0);
 		/* else  we lose race and someone else inserts
 		 * it first, don't bother updating
 		 */
 		spin_unlock(&br->hash_lock);
 	}
 }
	/*
	* Forwarding database
	* Linux ethernet bridge
	*
	* Authors:
	* Lennert Buytenhek <buytenh@gnu.org>
	*
	* $Id: br_fdb.c,v 1.6 2002/01/17 00:57:07 davem Exp $
	*
	* 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.
	*/

	#include <linux/kernel.h>
	#include <linux/init.h>
	#include <linux/spinlock.h>
	#include <linux/times.h>
	#include <linux/netdevice.h>
	#include <linux/etherdevice.h>
	#include <linux/jhash.h>
	#include <linux/random.h>
	#include <asm/atomic.h>
	#include <asm/unaligned.h>
	#include "br_private.h"

	static struct kmem_cache *br_fdb_cache __read_mostly;
	static int fdb_insert(struct net_bridge br, struct net_bridge_port source,
	const unsigned char *addr);

	static u32 fdb_salt __read_mostly;

	int __init br_fdb_init(void)
	{
	br_fdb_cache = kmem_cache_create("bridge_fdb_cache",
	sizeof(struct net_bridge_fdb_entry),
	0,
	SLAB_HWCACHE_ALIGN, NULL);
	if (!br_fdb_cache)
	return -ENOMEM;

	get_random_bytes(&fdb_salt, sizeof(fdb_salt));
	return 0;
	}

	void __exit br_fdb_fini(void)
	{
	kmem_cache_destroy(br_fdb_cache);
	}


	/* if topology_changing then use forward_delay (default 15 sec)
	* otherwise keep longer (default 5 minutes)
	*/
	static inline unsigned long hold_time(const struct net_bridge *br)
	{
	return br->topology_change ? br->forward_delay : br->ageing_time;
	}

	static inline int has_expired(const struct net_bridge *br,
	const struct net_bridge_fdb_entry *fdb)
	{
	return !fdb->is_static
	&& time_before_eq(fdb->ageing_timer + hold_time(br), jiffies);
	}

	static inline int br_mac_hash(const unsigned char *mac)
	{
	/* use 1 byte of OUI cnd 3 bytes of NIC */
	u32 key = get_unaligned((u32 *)(mac + 2));
	return jhash_1word(key, fdb_salt) & (BR_HASH_SIZE - 1);
	}

	static inline void fdb_delete(struct net_bridge_fdb_entry *f)
	{
	hlist_del_rcu(&f->hlist);
	br_fdb_put(f);
	}

	void br_fdb_changeaddr(struct net_bridge_port p, const unsigned char newaddr)
	{
	struct net_bridge *br = p->br;
	int i;

	spin_lock_bh(&br->hash_lock);

	/* Search all chains since old address/hash is unknown */
	for (i = 0; i < BR_HASH_SIZE; i++) {
	struct hlist_node *h;
	hlist_for_each(h, &br->hash[i]) {
	struct net_bridge_fdb_entry *f;

	f = hlist_entry(h, struct net_bridge_fdb_entry, hlist);
	if (f->dst == p && f->is_local) {
	/* maybe another port has same hw addr? */
	struct net_bridge_port *op;
	list_for_each_entry(op, &br->port_list, list) {
	if (op != p &&
	!compare_ether_addr(op->dev->dev_addr,
	f->addr.addr)) {
	f->dst = op;
	goto insert;
	}
	}

	/* delete old one */
	fdb_delete(f);
	goto insert;
	}
	}
	}
	insert:
	/* insert new address, may fail if invalid address or dup. */
	fdb_insert(br, p, newaddr);

	spin_unlock_bh(&br->hash_lock);
	}

	void br_fdb_cleanup(unsigned long _data)
	{
	struct net_bridge br = (struct net_bridge )_data;
	unsigned long delay = hold_time(br);
	unsigned long next_timer = jiffies + br->forward_delay;
	int i;

	spin_lock_bh(&br->hash_lock);
	for (i = 0; i < BR_HASH_SIZE; i++) {
	struct net_bridge_fdb_entry *f;
	struct hlist_node h, n;

	hlist_for_each_entry_safe(f, h, n, &br->hash[i], hlist) {
	unsigned long this_timer;
	if (f->is_static)
	continue;
	this_timer = f->ageing_timer + delay;
	if (time_before_eq(this_timer, jiffies))
	fdb_delete(f);
	else if (this_timer < next_timer)
	next_timer = this_timer;
	}
	}
	spin_unlock_bh(&br->hash_lock);

	/* Add HZ/4 to ensure we round the jiffies upwards to be after the next
	* timer, otherwise we might round down and will have no-op run. */
	mod_timer(&br->gc_timer, round_jiffies(next_timer + HZ/4));
	}

	/* Completely flush all dynamic entries in forwarding database.*/
	void br_fdb_flush(struct net_bridge *br)
	{
	int i;

	spin_lock_bh(&br->hash_lock);
	for (i = 0; i < BR_HASH_SIZE; i++) {
	struct net_bridge_fdb_entry *f;
	struct hlist_node h, n;
	hlist_for_each_entry_safe(f, h, n, &br->hash[i], hlist) {
	if (!f->is_static)
	fdb_delete(f);
	}
	}
	spin_unlock_bh(&br->hash_lock);
	}

	/* Flush all entries refering to a specific port.
	* if do_all is set also flush static entries
	*/
	void br_fdb_delete_by_port(struct net_bridge *br,
	const struct net_bridge_port *p,
	int do_all)
	{
	int i;

	spin_lock_bh(&br->hash_lock);
	for (i = 0; i < BR_HASH_SIZE; i++) {
	struct hlist_node h, g;

	hlist_for_each_safe(h, g, &br->hash[i]) {
	struct net_bridge_fdb_entry *f
	= hlist_entry(h, struct net_bridge_fdb_entry, hlist);
	if (f->dst != p)
	continue;

	if (f->is_static && !do_all)
	continue;
	/*
	* if multiple ports all have the same device address
	* then when one port is deleted, assign
	* the local entry to other port
	*/
	if (f->is_local) {
	struct net_bridge_port *op;
	list_for_each_entry(op, &br->port_list, list) {
	if (op != p &&
	!compare_ether_addr(op->dev->dev_addr,
	f->addr.addr)) {
	f->dst = op;
	goto skip_delete;
	}
	}
	}

	fdb_delete(f);
	skip_delete: ;
	}
	}
	spin_unlock_bh(&br->hash_lock);
	}

	/* No locking or refcounting, assumes caller has no preempt (rcu_read_lock) */
	struct net_bridge_fdb_entry __br_fdb_get(struct net_bridge br,
	const unsigned char *addr)
	{
	struct hlist_node *h;
	struct net_bridge_fdb_entry *fdb;

	hlist_for_each_entry_rcu(fdb, h, &br->hash[br_mac_hash(addr)], hlist) {
	if (!compare_ether_addr(fdb->addr.addr, addr)) {
	if (unlikely(has_expired(br, fdb)))
	break;
	return fdb;
	}
	}

	return NULL;
	}

	/* Interface used by ATM hook that keeps a ref count */
	struct net_bridge_fdb_entry br_fdb_get(struct net_bridge br,
	unsigned char *addr)
	{
	struct net_bridge_fdb_entry *fdb;

	rcu_read_lock();
	fdb = __br_fdb_get(br, addr);
	if (fdb && !atomic_inc_not_zero(&fdb->use_count))
	fdb = NULL;
	rcu_read_unlock();
	return fdb;
	}

	static void fdb_rcu_free(struct rcu_head *head)
	{
	struct net_bridge_fdb_entry *ent
	= container_of(head, struct net_bridge_fdb_entry, rcu);
	kmem_cache_free(br_fdb_cache, ent);
	}

	/* Set entry up for deletion with RCU */
	void br_fdb_put(struct net_bridge_fdb_entry *ent)
	{
	if (atomic_dec_and_test(&ent->use_count))
	call_rcu(&ent->rcu, fdb_rcu_free);
	}

	/*
	* Fill buffer with forwarding table records in
	* the API format.
	*/
	int br_fdb_fillbuf(struct net_bridge br, void buf,
	unsigned long maxnum, unsigned long skip)
	{
	struct __fdb_entry *fe = buf;
	int i, num = 0;
	struct hlist_node *h;
	struct net_bridge_fdb_entry *f;

	memset(buf, 0, maxnum*sizeof(struct __fdb_entry));

	rcu_read_lock();
	for (i = 0; i < BR_HASH_SIZE; i++) {
	hlist_for_each_entry_rcu(f, h, &br->hash[i], hlist) {
	if (num >= maxnum)
	goto out;

	if (has_expired(br, f))
	continue;

	if (skip) {
	--skip;
	continue;
	}

	/* convert from internal format to API */
	memcpy(fe->mac_addr, f->addr.addr, ETH_ALEN);
	fe->port_no = f->dst->port_no;
	fe->is_local = f->is_local;
	if (!f->is_static)
	fe->ageing_timer_value = jiffies_to_clock_t(jiffies - f->ageing_timer);
	++fe;
	++num;
	}
	}

	out:
	rcu_read_unlock();

	return num;
	}

	static inline struct net_bridge_fdb_entry fdb_find(struct hlist_head head,
	const unsigned char *addr)
	{
	struct hlist_node *h;
	struct net_bridge_fdb_entry *fdb;

	hlist_for_each_entry_rcu(fdb, h, head, hlist) {
	if (!compare_ether_addr(fdb->addr.addr, addr))
	return fdb;
	}
	return NULL;
	}

	static struct net_bridge_fdb_entry fdb_create(struct hlist_head head,
	struct net_bridge_port *source,
	const unsigned char *addr,
	int is_local)
	{
	struct net_bridge_fdb_entry *fdb;

	fdb = kmem_cache_alloc(br_fdb_cache, GFP_ATOMIC);
	if (fdb) {
	memcpy(fdb->addr.addr, addr, ETH_ALEN);
	atomic_set(&fdb->use_count, 1);
	hlist_add_head_rcu(&fdb->hlist, head);

	fdb->dst = source;
	fdb->is_local = is_local;
	fdb->is_static = is_local;
	fdb->ageing_timer = jiffies;
	}
	return fdb;
	}

	static int fdb_insert(struct net_bridge br, struct net_bridge_port source,
	const unsigned char *addr)
	{
	struct hlist_head *head = &br->hash[br_mac_hash(addr)];
	struct net_bridge_fdb_entry *fdb;

	if (!is_valid_ether_addr(addr))
	return -EINVAL;

	fdb = fdb_find(head, addr);
	if (fdb) {
	/* it is okay to have multiple ports with same
	* address, just use the first one.
	*/
	if (fdb->is_local)
	return 0;

	printk(KERN_WARNING "%s adding interface with same address "
	"as a received packet\n",
	source->dev->name);
	fdb_delete(fdb);
	}

	if (!fdb_create(head, source, addr, 1))
	return -ENOMEM;

	return 0;
	}

	int br_fdb_insert(struct net_bridge br, struct net_bridge_port source,
	const unsigned char *addr)
	{
	int ret;

	spin_lock_bh(&br->hash_lock);
	ret = fdb_insert(br, source, addr);
	spin_unlock_bh(&br->hash_lock);
	return ret;
	}

	void br_fdb_update(struct net_bridge br, struct net_bridge_port source,
	const unsigned char *addr)
	{
	struct hlist_head *head = &br->hash[br_mac_hash(addr)];
	struct net_bridge_fdb_entry *fdb;

	/* some users want to always flood. */
	if (hold_time(br) == 0)
	return;

	fdb = fdb_find(head, addr);
	if (likely(fdb)) {
	/* attempt to update an entry for a local interface */
	if (unlikely(fdb->is_local)) {
	if (net_ratelimit())
	printk(KERN_WARNING "%s: received packet with "
	" own address as source address\n",
	source->dev->name);
	} else {
	/* fastpath: update of existing entry */
	fdb->dst = source;
	fdb->ageing_timer = jiffies;
	}
	} else {
	spin_lock(&br->hash_lock);
	if (!fdb_find(head, addr))
	fdb_create(head, source, addr, 0);
	/* else we lose race and someone else inserts
	* it first, don't bother updating
	*/
	spin_unlock(&br->hash_lock);
	}
	}