bridge: notify mdb changes via netlink

As Stephen mentioned, we need to monitor the mdb
changes in user-space, so add notifications via netlink too.

Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Stephen Hemminger <shemminger@vyatta.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Thomas Graf <tgraf@suug.ch>
Signed-off-by: Cong Wang <amwang@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/bridge/br_multicast.c b/net/bridge/br_multicast.c
index 847b98a1..d929586 100644
--- a/net/bridge/br_multicast.c
+++ b/net/bridge/br_multicast.c
@@ -681,6 +681,7 @@
 		    (unsigned long)p);
 
 	rcu_assign_pointer(*pp, p);
+	br_mdb_notify(br->dev, port, group, RTM_NEWMDB);
 
 found:
 	mod_timer(&p->timer, now + br->multicast_membership_interval);
@@ -1240,6 +1241,7 @@
 			hlist_del_init(&p->mglist);
 			del_timer(&p->timer);
 			call_rcu_bh(&p->rcu, br_multicast_free_pg);
+			br_mdb_notify(br->dev, port, group, RTM_DELMDB);
 
 			if (!mp->ports && !mp->mglist &&
 			    netif_running(br->dev))