net/virtio-user: check file descriptor before closing

[ upstream commit b56c12a ]

Valgrind complains that virtio_user is calling close(-1).
Fix this by adding check in virtio that is similar to existing code.

Fixes: 37a7eb2 ("net/virtio-user: add device emulation layer")

Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
Reviewed-by: Tiwei Bie <tiwei.bie@intel.com>

drivers/net/virtio/virtio_user/virtio_user_dev.c

@@ -524,7 +524,8 @@ virtio_user_dev_uninit(struct virtio_user_dev *dev)
 		close(dev->kickfds[i]);
 	}
 
-	close(dev->vhostfd);
+	if (dev->vhostfd >= 0)
+		close(dev->vhostfd);
 
 	if (dev->is_server && dev->listenfd >= 0) {
 		close(dev->listenfd);