openvswitch: do not ignore netdev errors when creating tunnel vports

The creation of a tunnel vport (geneve, gre, vxlan) brings up a
corresponding netdev, a multi-step operation which can fail.

For example, changing a vxlan vport's netdev state to 'up' binds the
vport's socket to a UDP port - if the binding fails (e.g. due to the
port being in use), the error is currently ignored giving the
appearance that the tunnel vport creation completed successfully.

Signed-off-by: Martynas Pumputis <martynas@weave.works>
Acked-by: Pravin B Shelar <pshelar@ovn.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/openvswitch/vport-geneve.c b/net/openvswitch/vport-geneve.c
index 1a1fcec..5aaf3ba 100644
--- a/net/openvswitch/vport-geneve.c
+++ b/net/openvswitch/vport-geneve.c
@@ -93,7 +93,14 @@
 		return ERR_CAST(dev);
 	}
 
-	dev_change_flags(dev, dev->flags | IFF_UP);
+	err = dev_change_flags(dev, dev->flags | IFF_UP);
+	if (err < 0) {
+		rtnl_delete_link(dev);
+		rtnl_unlock();
+		ovs_vport_free(vport);
+		goto error;
+	}
+
 	rtnl_unlock();
 	return vport;
 error: