driver: macvtap: Unregister netdev rx_handler if macvtap_newlink fails

The macvtap_newlink registers the netdev rx_handler firstly, but it
does not unregister the handler if macvlan_common_newlink failed.
Signed-off-by: NGao Feng <fgao@ikuai8.com>
Acked-by: NJason Wang <jasowang@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/macvtap.c

@@ -491,7 +491,13 @@ static int macvtap_newlink(struct net *src_net,
 	/* Don't put anything that may fail after macvlan_common_newlink
 	 * because we can't undo what it does.
 	 */
-	return macvlan_common_newlink(src_net, dev, tb, data);
+	err = macvlan_common_newlink(src_net, dev, tb, data);
+	if (err) {
+		netdev_rx_handler_unregister(dev);
+		return err;
+	}
+
+	return 0;
 }
 
 static void macvtap_dellink(struct net_device *dev,