bridge: support for ndo_fdb_get

This patch implements ndo_fdb_get for the bridge
fdb.

Signed-off-by: Roopa Prabhu <roopa@cumulusnetworks.com>
Acked-by: Nikolay Aleksandrov <nikolay@cumulusnetworks.com>
Reviewed-by: David Ahern <dsa@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/bridge/br_device.c

@@ -403,6 +403,7 @@ static const struct net_device_ops br_netdev_ops = {
 	.ndo_fdb_add		 = br_fdb_add,
 	.ndo_fdb_del		 = br_fdb_delete,
 	.ndo_fdb_dump		 = br_fdb_dump,
+	.ndo_fdb_get		 = br_fdb_get,
 	.ndo_bridge_getlink	 = br_getlink,
 	.ndo_bridge_setlink	 = br_setlink,
 	.ndo_bridge_dellink	 = br_dellink,

net/bridge/br_fdb.c

@@ -773,6 +773,32 @@ skip:
 	return err;
 }
 
+int br_fdb_get(struct sk_buff *skb,
+	       struct nlattr *tb[],
+	       struct net_device *dev,
+	       const unsigned char *addr,
+	       u16 vid, u32 portid, u32 seq,
+	       struct netlink_ext_ack *extack)
+{
+	struct net_bridge *br = netdev_priv(dev);
+	struct net_bridge_fdb_entry *f;
+	int err = 0;
+
+	rcu_read_lock();
+	f = br_fdb_find_rcu(br, addr, vid);
+	if (!f) {
+		NL_SET_ERR_MSG(extack, "Fdb entry not found");
+		err = -ENOENT;
+		goto errout;
+	}
+
+	err = fdb_fill_info(skb, br, f, portid, seq,
+			    RTM_NEWNEIGH, 0);
+errout:
+	rcu_read_unlock();
+	return err;
+}
+
 /* Update (create or replace) forwarding database entry */
 static int fdb_add_entry(struct net_bridge *br, struct net_bridge_port *source,
 			 const u8 *addr, u16 state, u16 flags, u16 vid,

net/bridge/br_private.h

@@ -575,6 +575,9 @@ int br_fdb_add(struct ndmsg *nlh, struct nlattr *tb[], struct net_device *dev,
 	       const unsigned char *addr, u16 vid, u16 nlh_flags);
 int br_fdb_dump(struct sk_buff *skb, struct netlink_callback *cb,
 		struct net_device *dev, struct net_device *fdev, int *idx);
+int br_fdb_get(struct sk_buff *skb, struct nlattr *tb[], struct net_device *dev,
+	       const unsigned char *addr, u16 vid, u32 portid, u32 seq,
+	       struct netlink_ext_ack *extack);
 int br_fdb_sync_static(struct net_bridge *br, struct net_bridge_port *p);
 void br_fdb_unsync_static(struct net_bridge *br, struct net_bridge_port *p);
 int br_fdb_external_learn_add(struct net_bridge *br, struct net_bridge_port *p,