bridge: fdb dumping takes a filter device

Dumping a bridge fdb dumps every fdb entry
held. With this change we are going to filter
on selected bridge port.

Signed-off-by: Jamal Hadi Salim <jhs@mojatatu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/bridge/br_fdb.c b/net/bridge/br_fdb.c
index 7be3366..6edecd1 100644
--- a/net/bridge/br_fdb.c
+++ b/net/bridge/br_fdb.c
@@ -676,6 +676,7 @@
 int br_fdb_dump(struct sk_buff *skb,
 		struct netlink_callback *cb,
 		struct net_device *dev,
+		struct net_device *filter_dev,
 		int idx)
 {
 	struct net_bridge *br = netdev_priv(dev);
@@ -691,6 +692,10 @@
 			if (idx < cb->args[0])
 				goto skip;
 
+			if (filter_dev && (!f->dst || !f->dst->dev ||
+					   f->dst->dev != filter_dev))
+				goto skip;
+
 			if (fdb_fill_info(skb, br, f,
 					  NETLINK_CB(cb->skb).portid,
 					  cb->nlh->nlmsg_seq,