net: vrf: Add extack messages for enslave errors

Signed-off-by: David Ahern <dsahern@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/vrf.c

@@ -772,8 +772,11 @@ static int do_vrf_add_slave(struct net_device *dev, struct net_device *port_dev,
 	/* do not allow loopback device to be enslaved to a VRF.
 	 * The vrf device acts as the loopback for the vrf.
 	 */
-	if (port_dev == dev_net(dev)->loopback_dev)
+	if (port_dev == dev_net(dev)->loopback_dev) {
+		NL_SET_ERR_MSG(extack,
+			       "Can not enslave loopback device to a VRF");
 		return -EOPNOTSUPP;
+	}
 
 	port_dev->priv_flags |= IFF_L3MDEV_SLAVE;
 	ret = netdev_master_upper_dev_link(port_dev, dev, NULL, NULL, extack);
@@ -792,7 +795,13 @@ err:
 static int vrf_add_slave(struct net_device *dev, struct net_device *port_dev,
 			 struct netlink_ext_ack *extack)
 {
-	if (netif_is_l3_master(port_dev) || netif_is_l3_slave(port_dev))
+	if (netif_is_l3_master(port_dev)) {
+		NL_SET_ERR_MSG(extack,
+			       "Can not enslave an L3 master device to a VRF");
+		return -EINVAL;
+	}
+
+	if (netif_is_l3_slave(port_dev))
 		return -EINVAL;
 
 	return do_vrf_add_slave(dev, port_dev, extack);