usb: gadget: uvc: only pump video data if necessary

If the streaming endpoint is not enabled, the worker has nothing to do.
In the case buffers are still queued, this patch ensures that it will bail
out without handling any data.

Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Paul Elder <paul.elder@ideasonboard.com>
Signed-off-by: Michael Grzeschik <m.grzeschik@pengutronix.de>
Link: https://lore.kernel.org/r/20211017215017.18392-6-m.grzeschik@pengutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/gadget/function/uvc_video.c

@@ -334,12 +334,12 @@ static void uvcg_video_pump(struct work_struct *work)
 {
 	struct uvc_video *video = container_of(work, struct uvc_video, pump);
 	struct uvc_video_queue *queue = &video->queue;
-	struct usb_request *req;
+	struct usb_request *req = NULL;
 	struct uvc_buffer *buf;
 	unsigned long flags;
 	int ret;
 
-	while (1) {
+	while (video->ep->enabled) {
 		/* Retrieve the first available USB request, protected by the
 		 * request lock.
 		 */
@@ -389,6 +389,9 @@ static void uvcg_video_pump(struct work_struct *work)
 		video->req_int_count++;
 	}
 
+	if (!req)
+		return;
+
 	spin_lock_irqsave(&video->req_lock, flags);
 	list_add_tail(&req->list, &video->req_free);
 	spin_unlock_irqrestore(&video->req_lock, flags);