commit 619d9b710c upstream.
usb_kill_urb warranties that all the handlers are finished when it
returns, but does not protect against threads that might be handling
asynchronously the urb.
For UVC, the function uvc_ctrl_status_event_async() takes care of
control changes asynchronously.
If the code is executed in the following order:
CPU 0 CPU 1
===== =====
uvc_status_complete()
uvc_status_stop()
uvc_ctrl_status_event_work()
uvc_status_start() -> FAIL
Then uvc_status_start will keep failing and this error will be shown:
<4>[ 5.540139] URB 0000000000000000 submitted while active
drivers/usb/core/urb.c:378 usb_submit_urb+0x4c3/0x528
Let's improve the current situation, by not re-submiting the urb if
we are stopping the status event. Also process the queued work
(if any) during stop.
CPU 0 CPU 1
===== =====
uvc_status_complete()
uvc_status_stop()
uvc_status_start()
uvc_ctrl_status_event_work() -> FAIL
Hopefully, with the usb layer protection this should be enough to cover
all the cases.
Cc: stable@vger.kernel.org
Fixes: e5225c820c ("media: uvcvideo: Send a control event when a Control Change interrupt arrives")
Reviewed-by: Yunke Cao <yunkec@chromium.org>
Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
8e62139840