Hi Kieran,
On Wed, Nov 7, 2018 at 12:13 AM Kieran Bingham
<kieran.bingham@xxxxxxxxxxxxxxxx> wrote:
>
> Hi Tomasz,
>
> On 07/08/2018 10:54, Tomasz Figa wrote:
> > Hi Kieran,
> >
> > On Wed, Mar 28, 2018 at 1:47 AM Kieran Bingham
> > <kieran.bingham@xxxxxxxxxxxxxxxx> wrote:
> > [snip]
> >> @@ -1544,25 +1594,29 @@ static int uvc_alloc_urb_buffers(struct uvc_streaming *stream,
> >> */
> >> static void uvc_uninit_video(struct uvc_streaming *stream, int free_buffers)
> >> {
> >> - struct urb *urb;
> >> - unsigned int i;
> >> + struct uvc_urb *uvc_urb;
> >>
> >> uvc_video_stats_stop(stream);
> >>
> >> - for (i = 0; i < UVC_URBS; ++i) {
> >> - struct uvc_urb *uvc_urb = &stream->uvc_urb[i];
> >> + /*
> >> + * We must poison the URBs rather than kill them to ensure that even
> >> + * after the completion handler returns, any asynchronous workqueues
> >> + * will be prevented from resubmitting the URBs
> >> + */
> >> + for_each_uvc_urb(uvc_urb, stream)
> >> + usb_poison_urb(uvc_urb->urb);
> >>
> >> - urb = uvc_urb->urb;
> >> - if (urb == NULL)
> >> - continue;
> >> + flush_workqueue(stream->async_wq);
> >>
> >> - usb_kill_urb(urb);
> >> - usb_free_urb(urb);
> >> + for_each_uvc_urb(uvc_urb, stream) {
> >> + usb_free_urb(uvc_urb->urb);
> >> uvc_urb->urb = NULL;
> >> }
> >>
> >> if (free_buffers)
> >> uvc_free_urb_buffers(stream);
> >> +
> >> + destroy_workqueue(stream->async_wq);
> >
> > In our testing, this function ends up being called twice, if before
> > suspend the camera is streaming and if the camera disconnects between
> > suspend and resume. This is because uvc_video_suspend() calls this
> > function (with free_buffers = 0), but uvc_video_resume() wouldn't call
> > uvc_init_video() due to an earlier failure and uvc_v4l2_release()
> > would end up calling this function again, while the workqueue is
> > already destroyed.
> >
> > The following diff seems to take care of it:
>
> Thank you for this. After discussing with Laurent, I have gone with the
> approach of keeping the workqueue for the lifetime of the stream, rather
> than the lifetime of the streamon.
>
Sounds good to me. Thanks for heads up!
Best regards,
Tomasz
