usb: gadget: uvc_video: unlock before submitting a request to ep

There could be chances where the usb_ep_queue() could fail and trigger
complete() handler with error status. In this case, if usb_ep_queue()
is called with lock held and the triggered complete() handler is waiting
for the same lock to be cleared could result in a deadlock situation and
could result in system hang. To aviod this scenerio, call usb_ep_queue()
with lock removed. This patch does the same.

Signed-off-by: Anurag Kumar Vulisha <anurag.kumar.vulisha@xilinx.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Signed-off-by: Piyush Mehta <piyush.mehta@xilinx.com>
State: pending

drivers/usb/gadget/function/uvc_video.c

@@ -332,11 +332,15 @@ int uvcg_video_pump(struct uvc_video *video)
 
 		video->encode(req, video, buf);
 
+		spin_unlock_irqrestore(&queue->irqlock, flags);
+
 		/* Queue the USB request */
 		ret = uvcg_video_ep_queue(video, req);
 		spin_unlock_irqrestore(&queue->irqlock, flags);
 
 		if (ret < 0) {
+			printk(KERN_INFO "Failed to queue request (%d)\n", ret);
+			usb_ep_set_halt(video->ep);
 			uvcg_queue_cancel(queue, 0);
 			break;
 		}