netdev-linux: do not warn when getting stats for netdev with no vport

When there is no vport for a given netdev, dpif_netlink_vport_get might return
ENODEV. Do not warn a failure to get port stats when that's the case.

This happens when the userspace switch is used.

Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@redhat.com>
Signed-off-by: Ben Pfaff <blp@nicira.com>

lib/netdev-linux.c

@@ -1536,7 +1536,7 @@ get_stats_via_vport(const struct netdev *netdev_,
         int error;
 
         error = get_stats_via_vport__(netdev_, stats);
-        if (error && error != ENOENT) {
+        if (error && error != ENOENT && error != ENODEV) {
             VLOG_WARN_RL(&rl, "%s: obtaining netdev stats via vport failed "
                          "(%s)",
                          netdev_get_name(netdev_), ovs_strerror(error));