/*
   *	Forwarding database
   *	Linux ethernet bridge
   *
   *	Authors:
   *	Lennert Buytenhek		<buytenh@gnu.org>
   *

   *	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/rculist.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 <linux/slab.h>

  #include <linux/atomic.h>

  #include <asm/unaligned.h>

  #include <linux/if_vlan.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, u16 vid);

  static void fdb_notify(struct net_bridge *br,
  		       const struct net_bridge_fdb_entry *, int);

  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 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->updated + hold_time(br), jiffies);

  }

  static inline int br_mac_hash(const unsigned char *mac, __u16 vid)

  {

  	/* use 1 byte of OUI and 3 bytes of NIC */

  	u32 key = get_unaligned((u32 *)(mac + 2));

  	return jhash_2words(key, vid, fdb_salt) & (BR_HASH_SIZE - 1);

  }

  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);
  }

  static void fdb_delete(struct net_bridge *br, struct net_bridge_fdb_entry *f)

  {
  	hlist_del_rcu(&f->hlist);

  	fdb_notify(br, f, RTM_DELNEIGH);

  	call_rcu(&f->rcu, fdb_rcu_free);

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

  	bool no_vlan = (nbp_get_vlan_info(p) == NULL) ? true : false;

  	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;

  				u16 vid = f->vlan_id;

  				list_for_each_entry(op, &br->port_list, list) {

  					if (op != p &&

  					    ether_addr_equal(op->dev->dev_addr,

  							     f->addr.addr) &&
  					    nbp_vlan_find(op, vid)) {

  						f->dst = op;
  						goto insert;
  					}
  				}
  
  				/* delete old one */

  				fdb_delete(br, f);

  insert:
  				/* insert new address,  may fail if invalid
  				 * address or dup.
  				 */
  				fdb_insert(br, p, newaddr, vid);
  
  				/* if this port has no vlan information
  				 * configured, we can safely be done at
  				 * this point.
  				 */
  				if (no_vlan)
  					goto done;

  			}
  		}
  	}

  done:

  	spin_unlock_bh(&br->hash_lock);
  }

  void br_fdb_change_mac_address(struct net_bridge *br, const u8 *newaddr)
  {
  	struct net_bridge_fdb_entry *f;

  	struct net_port_vlans *pv;
  	u16 vid = 0;

  
  	/* If old entry was unassociated with any port, then delete it. */

  	f = __br_fdb_get(br, br->dev->dev_addr, 0);

  	if (f && f->is_local && !f->dst)
  		fdb_delete(br, f);

  	fdb_insert(br, NULL, newaddr, 0);
  
  	/* Now remove and add entries for every VLAN configured on the
  	 * bridge.  This function runs under RTNL so the bitmap will not
  	 * change from under us.
  	 */
  	pv = br_get_vlan_info(br);
  	if (!pv)
  		return;

  	for_each_set_bit_from(vid, pv->vlan_bitmap, VLAN_N_VID) {

  		f = __br_fdb_get(br, br->dev->dev_addr, vid);
  		if (f && f->is_local && !f->dst)
  			fdb_delete(br, f);
  		fdb_insert(br, NULL, newaddr, vid);
  	}

  }

  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->ageing_time;

  	int i;

  	spin_lock(&br->hash_lock);

  	for (i = 0; i < BR_HASH_SIZE; i++) {
  		struct net_bridge_fdb_entry *f;

  		struct hlist_node *n;

  		hlist_for_each_entry_safe(f, n, &br->hash[i], hlist) {

  			unsigned long this_timer;
  			if (f->is_static)
  				continue;

  			this_timer = f->updated + delay;

  			if (time_before_eq(this_timer, jiffies))

  				fdb_delete(br, f);

  			else if (time_before(this_timer, next_timer))

  				next_timer = this_timer;

  		}
  	}

  	spin_unlock(&br->hash_lock);

  	mod_timer(&br->gc_timer, round_jiffies_up(next_timer));

  }

  /* 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 *n;
  		hlist_for_each_entry_safe(f, n, &br->hash[i], hlist) {

  			if (!f->is_static)

  				fdb_delete(br, f);

  		}
  	}
  	spin_unlock_bh(&br->hash_lock);
  }

  /* Flush all entries referring 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 &&

  					    ether_addr_equal(op->dev->dev_addr,
  							     f->addr.addr)) {

  						f->dst = op;
  						goto skip_delete;
  					}
  				}
  			}

  			fdb_delete(br, f);

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

  /* No locking or refcounting, assumes caller has rcu_read_lock */

  struct net_bridge_fdb_entry *__br_fdb_get(struct net_bridge *br,

  					  const unsigned char *addr,
  					  __u16 vid)

  {

  	struct net_bridge_fdb_entry *fdb;

  	hlist_for_each_entry_rcu(fdb,

  				&br->hash[br_mac_hash(addr, vid)], hlist) {
  		if (ether_addr_equal(fdb->addr.addr, addr) &&
  		    fdb->vlan_id == vid) {

  			if (unlikely(has_expired(br, fdb)))
  				break;
  			return fdb;
  		}
  	}
  
  	return NULL;
  }

  #if IS_ENABLED(CONFIG_ATM_LANE)

  /* Interface used by ATM LANE hook to test
   * if an addr is on some other bridge port */
  int br_fdb_test_addr(struct net_device *dev, unsigned char *addr)

  {
  	struct net_bridge_fdb_entry *fdb;

  	struct net_bridge_port *port;

  	int ret;

  	rcu_read_lock();

  	port = br_port_get_rcu(dev);
  	if (!port)
  		ret = 0;
  	else {

  		fdb = __br_fdb_get(port->br, addr, 0);

  		ret = fdb && fdb->dst && fdb->dst->dev != dev &&

  			fdb->dst->state == BR_STATE_FORWARDING;
  	}

  	rcu_read_unlock();

  	return ret;

  }

  #endif /* CONFIG_ATM_LANE */

  
  /*

   * 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 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, &br->hash[i], hlist) {

  			if (num >= maxnum)
  				goto out;

  			if (has_expired(br, f))

  				continue;

  			/* ignore pseudo entry for local MAC address */
  			if (!f->dst)
  				continue;

  			if (skip) {
  				--skip;
  				continue;
  			}
  
  			/* convert from internal format to API */
  			memcpy(fe->mac_addr, f->addr.addr, ETH_ALEN);

  
  			/* due to ABI compat need to split into hi/lo */

  			fe->port_no = f->dst->port_no;

  			fe->port_hi = f->dst->port_no >> 8;

  			fe->is_local = f->is_local;
  			if (!f->is_static)

  				fe->ageing_timer_value = jiffies_delta_to_clock_t(jiffies - f->updated);

  			++fe;
  			++num;
  		}
  	}
  
   out:
  	rcu_read_unlock();
  
  	return num;
  }

  static struct net_bridge_fdb_entry *fdb_find(struct hlist_head *head,

  					     const unsigned char *addr,
  					     __u16 vid)

  {

  	struct net_bridge_fdb_entry *fdb;

  	hlist_for_each_entry(fdb, head, hlist) {

  		if (ether_addr_equal(fdb->addr.addr, addr) &&
  		    fdb->vlan_id == vid)

  			return fdb;
  	}
  	return NULL;
  }
  
  static struct net_bridge_fdb_entry *fdb_find_rcu(struct hlist_head *head,

  						 const unsigned char *addr,
  						 __u16 vid)

  {

  	struct net_bridge_fdb_entry *fdb;

  	hlist_for_each_entry_rcu(fdb, head, hlist) {

  		if (ether_addr_equal(fdb->addr.addr, addr) &&
  		    fdb->vlan_id == vid)

  			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,
  					       __u16 vid)

  {
  	struct net_bridge_fdb_entry *fdb;
  
  	fdb = kmem_cache_alloc(br_fdb_cache, GFP_ATOMIC);
  	if (fdb) {
  		memcpy(fdb->addr.addr, addr, ETH_ALEN);

  		fdb->dst = source;

  		fdb->vlan_id = vid;

  		fdb->is_local = 0;
  		fdb->is_static = 0;

  		fdb->updated = fdb->used = jiffies;

  		hlist_add_head_rcu(&fdb->hlist, head);

  	}
  	return fdb;
  }
  
  static int fdb_insert(struct net_bridge *br, struct net_bridge_port *source,

  		  const unsigned char *addr, u16 vid)

  {

  	struct hlist_head *head = &br->hash[br_mac_hash(addr, vid)];

  	struct net_bridge_fdb_entry *fdb;
  
  	if (!is_valid_ether_addr(addr))
  		return -EINVAL;

  	fdb = fdb_find(head, addr, vid);

  	if (fdb) {

  		/* it is okay to have multiple ports with same

  		 * address, just use the first one.
  		 */

  		if (fdb->is_local)

  			return 0;

  		br_warn(br, "adding interface %s with same address "

  		       "as a received packet
  ",

  		       source ? source->dev->name : br->dev->name);

  		fdb_delete(br, fdb);

  	}

  	fdb = fdb_create(head, source, addr, vid);

  	if (!fdb)

  		return -ENOMEM;

  	fdb->is_local = fdb->is_static = 1;

  	fdb_notify(br, fdb, RTM_NEWNEIGH);

  	return 0;
  }

  /* Add entry for local address of interface */

  int br_fdb_insert(struct net_bridge *br, struct net_bridge_port *source,

  		  const unsigned char *addr, u16 vid)

  {
  	int ret;
  
  	spin_lock_bh(&br->hash_lock);

  	ret = fdb_insert(br, source, addr, vid);

  	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, u16 vid)

  {

  	struct hlist_head *head = &br->hash[br_mac_hash(addr, vid)];

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

  	/* ignore packets unless we are using this port */
  	if (!(source->state == BR_STATE_LEARNING ||
  	      source->state == BR_STATE_FORWARDING))
  		return;

  	fdb = fdb_find_rcu(head, addr, vid);

  	if (likely(fdb)) {
  		/* attempt to update an entry for a local interface */
  		if (unlikely(fdb->is_local)) {

  			if (net_ratelimit())

  				br_warn(br, "received packet on %s with "
  					"own address as source address
  ",
  					source->dev->name);

  		} else {
  			/* fastpath: update of existing entry */
  			fdb->dst = source;

  			fdb->updated = jiffies;

  		}
  	} else {

  		spin_lock(&br->hash_lock);

  		if (likely(!fdb_find(head, addr, vid))) {
  			fdb = fdb_create(head, source, addr, vid);

  			if (fdb)

  				fdb_notify(br, fdb, RTM_NEWNEIGH);

  		}

  		/* else  we lose race and someone else inserts
  		 * it first, don't bother updating
  		 */

  		spin_unlock(&br->hash_lock);

  	}

  }

  
  static int fdb_to_nud(const struct net_bridge_fdb_entry *fdb)
  {
  	if (fdb->is_local)
  		return NUD_PERMANENT;
  	else if (fdb->is_static)
  		return NUD_NOARP;
  	else if (has_expired(fdb->dst->br, fdb))
  		return NUD_STALE;
  	else
  		return NUD_REACHABLE;
  }

  static int fdb_fill_info(struct sk_buff *skb, const struct net_bridge *br,

  			 const struct net_bridge_fdb_entry *fdb,

  			 u32 portid, u32 seq, int type, unsigned int flags)

  {
  	unsigned long now = jiffies;
  	struct nda_cacheinfo ci;
  	struct nlmsghdr *nlh;
  	struct ndmsg *ndm;

  	nlh = nlmsg_put(skb, portid, seq, type, sizeof(*ndm), flags);

  	if (nlh == NULL)
  		return -EMSGSIZE;

  	ndm = nlmsg_data(nlh);
  	ndm->ndm_family	 = AF_BRIDGE;
  	ndm->ndm_pad1    = 0;
  	ndm->ndm_pad2    = 0;
  	ndm->ndm_flags	 = 0;
  	ndm->ndm_type	 = 0;

  	ndm->ndm_ifindex = fdb->dst ? fdb->dst->dev->ifindex : br->dev->ifindex;

  	ndm->ndm_state   = fdb_to_nud(fdb);

  	if (nla_put(skb, NDA_LLADDR, ETH_ALEN, &fdb->addr))
  		goto nla_put_failure;

  	ci.ndm_used	 = jiffies_to_clock_t(now - fdb->used);
  	ci.ndm_confirmed = 0;
  	ci.ndm_updated	 = jiffies_to_clock_t(now - fdb->updated);
  	ci.ndm_refcnt	 = 0;

  	if (nla_put(skb, NDA_CACHEINFO, sizeof(ci), &ci))
  		goto nla_put_failure;

  
  	if (nla_put(skb, NDA_VLAN, sizeof(u16), &fdb->vlan_id))
  		goto nla_put_failure;

  	return nlmsg_end(skb, nlh);
  
  nla_put_failure:
  	nlmsg_cancel(skb, nlh);
  	return -EMSGSIZE;
  }
  
  static inline size_t fdb_nlmsg_size(void)
  {
  	return NLMSG_ALIGN(sizeof(struct ndmsg))
  		+ nla_total_size(ETH_ALEN) /* NDA_LLADDR */

  		+ nla_total_size(sizeof(u16)) /* NDA_VLAN */

  		+ nla_total_size(sizeof(struct nda_cacheinfo));
  }

  static void fdb_notify(struct net_bridge *br,
  		       const struct net_bridge_fdb_entry *fdb, int type)

  {

  	struct net *net = dev_net(br->dev);

  	struct sk_buff *skb;
  	int err = -ENOBUFS;
  
  	skb = nlmsg_new(fdb_nlmsg_size(), GFP_ATOMIC);
  	if (skb == NULL)
  		goto errout;

  	err = fdb_fill_info(skb, br, fdb, 0, 0, type, 0);

  	if (err < 0) {
  		/* -EMSGSIZE implies BUG in fdb_nlmsg_size() */
  		WARN_ON(err == -EMSGSIZE);
  		kfree_skb(skb);
  		goto errout;
  	}
  	rtnl_notify(skb, net, 0, RTNLGRP_NEIGH, NULL, GFP_ATOMIC);
  	return;
  errout:
  	if (err < 0)
  		rtnl_set_sk_err(net, RTNLGRP_NEIGH, err);
  }
  
  /* Dump information about entries, in response to GETNEIGH */

  int br_fdb_dump(struct sk_buff *skb,
  		struct netlink_callback *cb,
  		struct net_device *dev,
  		int idx)

  {

  	struct net_bridge *br = netdev_priv(dev);
  	int i;

  	if (!(dev->priv_flags & IFF_EBRIDGE))
  		goto out;

  	for (i = 0; i < BR_HASH_SIZE; i++) {

  		struct net_bridge_fdb_entry *f;

  		hlist_for_each_entry_rcu(f, &br->hash[i], hlist) {

  			if (idx < cb->args[0])
  				goto skip;
  
  			if (fdb_fill_info(skb, br, f,

  					  NETLINK_CB(cb->skb).portid,

  					  cb->nlh->nlmsg_seq,
  					  RTM_NEWNEIGH,
  					  NLM_F_MULTI) < 0)
  				break;

  skip:

  			++idx;

  		}
  	}

  out:
  	return idx;

  }

  /* Update (create or replace) forwarding database entry */

  static int fdb_add_entry(struct net_bridge_port *source, const __u8 *addr,

  			 __u16 state, __u16 flags, __u16 vid)

  {
  	struct net_bridge *br = source->br;

  	struct hlist_head *head = &br->hash[br_mac_hash(addr, vid)];

  	struct net_bridge_fdb_entry *fdb;

  	bool modified = false;

  	fdb = fdb_find(head, addr, vid);

  	if (fdb == NULL) {
  		if (!(flags & NLM_F_CREATE))
  			return -ENOENT;

  		fdb = fdb_create(head, source, addr, vid);

  		if (!fdb)
  			return -ENOMEM;

  
  		modified = true;

  	} else {
  		if (flags & NLM_F_EXCL)
  			return -EEXIST;

  
  		if (fdb->dst != source) {
  			fdb->dst = source;
  			modified = true;
  		}

  	}
  
  	if (fdb_to_nud(fdb) != state) {
  		if (state & NUD_PERMANENT)
  			fdb->is_local = fdb->is_static = 1;
  		else if (state & NUD_NOARP) {
  			fdb->is_local = 0;
  			fdb->is_static = 1;
  		} else
  			fdb->is_local = fdb->is_static = 0;

  		modified = true;
  	}
  
  	fdb->used = jiffies;
  	if (modified) {
  		fdb->updated = jiffies;

  		fdb_notify(br, fdb, RTM_NEWNEIGH);

  	}

  	return 0;
  }

  static int __br_fdb_add(struct ndmsg *ndm, struct net_bridge_port *p,
  	       const unsigned char *addr, u16 nlh_flags, u16 vid)
  {
  	int err = 0;
  
  	if (ndm->ndm_flags & NTF_USE) {
  		rcu_read_lock();
  		br_fdb_update(p->br, p, addr, vid);
  		rcu_read_unlock();
  	} else {
  		spin_lock_bh(&p->br->hash_lock);
  		err = fdb_add_entry(p, addr, ndm->ndm_state,
  				    nlh_flags, vid);
  		spin_unlock_bh(&p->br->hash_lock);
  	}
  
  	return err;
  }

  /* Add new permanent fdb entry with RTM_NEWNEIGH */

  int br_fdb_add(struct ndmsg *ndm, struct nlattr *tb[],
  	       struct net_device *dev,

  	       const unsigned char *addr, u16 nlh_flags)

  {

  	struct net_bridge_port *p;

  	int err = 0;

  	struct net_port_vlans *pv;
  	unsigned short vid = VLAN_N_VID;

  	if (!(ndm->ndm_state & (NUD_PERMANENT|NUD_NOARP|NUD_REACHABLE))) {
  		pr_info("bridge: RTM_NEWNEIGH with invalid state %#x
  ", ndm->ndm_state);
  		return -EINVAL;
  	}

  	if (tb[NDA_VLAN]) {
  		if (nla_len(tb[NDA_VLAN]) != sizeof(unsigned short)) {
  			pr_info("bridge: RTM_NEWNEIGH with invalid vlan
  ");
  			return -EINVAL;
  		}
  
  		vid = nla_get_u16(tb[NDA_VLAN]);
  
  		if (vid >= VLAN_N_VID) {
  			pr_info("bridge: RTM_NEWNEIGH with invalid vlan id %d
  ",
  				vid);
  			return -EINVAL;
  		}
  	}

  	p = br_port_get_rtnl(dev);
  	if (p == NULL) {
  		pr_info("bridge: RTM_NEWNEIGH %s not a bridge port
  ",
  			dev->name);
  		return -EINVAL;
  	}

  	pv = nbp_get_vlan_info(p);
  	if (vid != VLAN_N_VID) {
  		if (!pv || !test_bit(vid, pv->vlan_bitmap)) {
  			pr_info("bridge: RTM_NEWNEIGH with unconfigured "
  				"vlan %d on port %s
  ", vid, dev->name);
  			return -EINVAL;
  		}
  
  		/* VID was specified, so use it. */
  		err = __br_fdb_add(ndm, p, addr, nlh_flags, vid);

  	} else {

  		if (!pv || bitmap_empty(pv->vlan_bitmap, VLAN_N_VID)) {

  			err = __br_fdb_add(ndm, p, addr, nlh_flags, 0);
  			goto out;
  		}
  
  		/* We have vlans configured on this port and user didn't
  		 * specify a VLAN.  To be nice, add/update entry for every
  		 * vlan on this port.
  		 */

  		for_each_set_bit(vid, pv->vlan_bitmap, VLAN_N_VID) {

  			err = __br_fdb_add(ndm, p, addr, nlh_flags, vid);
  			if (err)
  				goto out;

  		}

  	}

  out:

  	return err;
  }

  int fdb_delete_by_addr(struct net_bridge *br, const u8 *addr,
  		       u16 vlan)

  {

  	struct hlist_head *head = &br->hash[br_mac_hash(addr, vlan)];

  	struct net_bridge_fdb_entry *fdb;

  	fdb = fdb_find(head, addr, vlan);

  	if (!fdb)
  		return -ENOENT;

  	fdb_delete(br, fdb);

  	return 0;
  }

  static int __br_fdb_delete(struct net_bridge_port *p,
  			   const unsigned char *addr, u16 vid)
  {
  	int err;
  
  	spin_lock_bh(&p->br->hash_lock);
  	err = fdb_delete_by_addr(p->br, addr, vid);
  	spin_unlock_bh(&p->br->hash_lock);
  
  	return err;
  }

  /* Remove neighbor entry with RTM_DELNEIGH */

  int br_fdb_delete(struct ndmsg *ndm, struct nlattr *tb[],
  		  struct net_device *dev,

  		  const unsigned char *addr)

  {

  	struct net_bridge_port *p;

  	int err;

  	struct net_port_vlans *pv;
  	unsigned short vid = VLAN_N_VID;

  	if (tb[NDA_VLAN]) {
  		if (nla_len(tb[NDA_VLAN]) != sizeof(unsigned short)) {
  			pr_info("bridge: RTM_NEWNEIGH with invalid vlan
  ");
  			return -EINVAL;
  		}
  
  		vid = nla_get_u16(tb[NDA_VLAN]);
  
  		if (vid >= VLAN_N_VID) {
  			pr_info("bridge: RTM_NEWNEIGH with invalid vlan id %d
  ",
  				vid);
  			return -EINVAL;
  		}
  	}

  	p = br_port_get_rtnl(dev);
  	if (p == NULL) {
  		pr_info("bridge: RTM_DELNEIGH %s not a bridge port
  ",
  			dev->name);
  		return -EINVAL;
  	}

  	pv = nbp_get_vlan_info(p);
  	if (vid != VLAN_N_VID) {
  		if (!pv || !test_bit(vid, pv->vlan_bitmap)) {
  			pr_info("bridge: RTM_DELNEIGH with unconfigured "
  				"vlan %d on port %s
  ", vid, dev->name);
  			return -EINVAL;
  		}

  		err = __br_fdb_delete(p, addr, vid);
  	} else {

  		if (!pv || bitmap_empty(pv->vlan_bitmap, VLAN_N_VID)) {

  			err = __br_fdb_delete(p, addr, 0);
  			goto out;
  		}
  
  		/* We have vlans configured on this port and user didn't
  		 * specify a VLAN.  To be nice, add/update entry for every
  		 * vlan on this port.
  		 */
  		err = -ENOENT;

  		for_each_set_bit(vid, pv->vlan_bitmap, VLAN_N_VID) {

  			err &= __br_fdb_delete(p, addr, vid);

  		}
  	}
  out:

  	return err;
  }