When using command "ip tunnel add" to add a tunnel, the tunnel will be added twice,
through ip_tunnel_create() and ip_tunnel_update().
Because the second is unnecessary, so we can just break after adding tunnel
through ip_tunnel_create().
Signed-off-by: Duan Jiong <duanj.fnst@cn.fujitsu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
 
                if (!t && (cmd == SIOCADDTUNNEL)) {
                        t = ip_tunnel_create(net, itn, p);
-                       if (IS_ERR(t)) {
-                               err = PTR_ERR(t);
-                               break;
-                       }
+                       err = PTR_ERR_OR_ZERO(t);
+                       break;
                }
                if (dev != itn->fb_tunnel_dev && cmd == SIOCCHGTUNNEL) {
                        if (t != NULL) {