diff --git a/drivers/media/usb/uvc/uvc_status.c b/drivers/media/usb/uvc/uvc_status.c index 65f5356bebb3..b632cf5e3fe9 100644 --- a/drivers/media/usb/uvc/uvc_status.c +++ b/drivers/media/usb/uvc/uvc_status.c @@ -316,6 +316,16 @@ static int uvc_status_start(struct uvc_device *dev, gfp_t flags) if (!dev->int_urb) return 0; + /* + * If the previous uvc_status_stop() call was from the async work, + * the work may still be running. Wait for it to finish before we submit + * the urb. + */ + flush_work(&dev->async_ctrl.work); + + /* Clear the flush status if we were previously stopped. */ + smp_store_release(&dev->flush_status, false); + return usb_submit_urb(dev->int_urb, flags); } @@ -336,6 +346,15 @@ static void uvc_status_stop(struct uvc_device *dev) */ smp_store_release(&dev->flush_status, true); + /* + * If we are called from the event work function, the URB is guaranteed + * to not be in flight as it has completed and has not been resubmitted. + * There's no need to cancel the work (which would deadlock), or to kill + * the URB. + */ + if (current_work() == &w->work) + return; + /* * Cancel any pending asynchronous work. If any status event was queued, * process it synchronously. @@ -354,15 +373,6 @@ static void uvc_status_stop(struct uvc_device *dev) */ if (cancel_work_sync(&w->work)) uvc_ctrl_status_event(w->chain, w->ctrl, w->data); - - /* - * From this point, there are no events on the queue and the status URB - * is dead. No events will be queued until uvc_status_start() is called. - * The barrier is needed to make sure that flush_status is visible to - * uvc_ctrl_status_event_work() when uvc_status_start() will be called - * again. - */ - smp_store_release(&dev->flush_status, false); } int uvc_status_resume(struct uvc_device *dev)