bridge: implement [add/del]_slave ops

add possibility to addif/delif via rtnetlink

Signed-off-by: Jiri Pirko <jpirko@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/bridge/br_if.c b/net/bridge/br_if.c
index 2a6801d..dce8f00 100644
--- a/net/bridge/br_if.c
+++ b/net/bridge/br_if.c
@@ -148,6 +148,8 @@
 
 	netdev_rx_handler_unregister(dev);
 
+	netdev_set_master(dev, NULL);
+
 	br_multicast_del_port(p);
 
 	kobject_uevent(&p->kobj, KOBJ_REMOVE);
@@ -429,10 +431,14 @@
 	if (br_netpoll_info(br) && ((err = br_netpoll_enable(p))))
 		goto err3;
 
-	err = netdev_rx_handler_register(dev, br_handle_frame, p);
+	err = netdev_set_master(dev, br->dev);
 	if (err)
 		goto err3;
 
+	err = netdev_rx_handler_register(dev, br_handle_frame, p);
+	if (err)
+		goto err4;
+
 	dev->priv_flags |= IFF_BRIDGE_PORT;
 
 	dev_disable_lro(dev);
@@ -455,6 +461,9 @@
 	kobject_uevent(&p->kobj, KOBJ_ADD);
 
 	return 0;
+
+err4:
+	netdev_set_master(dev, NULL);
 err3:
 	sysfs_remove_link(br->ifobj, p->dev->name);
 err2: