net: vrf: Set slave's private flag before linking

Allow listeners of the subsequent CHANGEUPPER notification to retrieve
the VRF's table ID by calling l3mdev_fib_table() with the slave netdev.
Without this change, the netdev won't be considered an L3 slave and the
function would return 0.

This is consistent with other master device such as bridge and bond that
set the slave's private flag before linking. It also makes
do_vrf_{add,del}_slave() symmetric.
Signed-off-by: NIdo Schimmel <idosch@mellanox.com>
Acked-by: NDavid Ahern <dsa@cumulusnetworks.com>
Signed-off-by: NJiri Pirko <jiri@mellanox.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/vrf.c

@@ -747,14 +747,18 @@ static int do_vrf_add_slave(struct net_device *dev, struct net_device *port_dev)
 {
 	int ret;
 
+	port_dev->priv_flags |= IFF_L3MDEV_SLAVE;
 	ret = netdev_master_upper_dev_link(port_dev, dev, NULL, NULL);
 	if (ret < 0)
-		return ret;
+		goto err;
 
-	port_dev->priv_flags |= IFF_L3MDEV_SLAVE;
 	cycle_netdev(port_dev);
 
 	return 0;
+
+err:
+	port_dev->priv_flags &= ~IFF_L3MDEV_SLAVE;
+	return ret;
 }
 
 static int vrf_add_slave(struct net_device *dev, struct net_device *port_dev)