virtio: release virtio index when fail to device_register

index can be reused by other virtio device.

Cc: stable@vger.kernel.org
Signed-off-by: weiping zhang <zhangweiping@didichuxing.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

drivers/virtio/virtio.c

@@ -333,6 +333,8 @@ int register_virtio_device(struct virtio_device *dev)
 	/* device_register() causes the bus infrastructure to look for a
 	 * matching driver. */
 	err = device_register(&dev->dev);
+	if (err)
+		ida_simple_remove(&virtio_index_ida, dev->index);
 out:
 	if (err)
 		virtio_add_status(dev, VIRTIO_CONFIG_S_FAILED);