With that patch, libv4l throws an error at some point, no crashes so far though:
libv4l2: error dequeuing buf: Invalid argument
read error 22, Invalid argument
On Tue, Dec 15, 2009 at 9:12 PM, Laurent Pinchart
<laurent.pinchart@xxxxxxxxxxxxxxxx> wrote:
> Hi Leandro and Pablo,
>
> could you please try the following patch ? It closes a race window that I
> believe could be at the core of your kernel panic.
>
> diff -r c1f376eae978 linux/drivers/media/video/uvc/uvc_queue.c
> --- a/linux/drivers/media/video/uvc/uvc_queue.c Sat Dec 12 18:57:17 2009 +0100
> +++ b/linux/drivers/media/video/uvc/uvc_queue.c Wed Dec 16 01:10:21 2009 +0100
> @@ -59,7 +59,7 @@
> * returns immediately.
> *
> * When the buffer is full, the completion handler removes it from the irq
> - * queue, marks it as ready (UVC_BUF_STATE_DONE) and wakes its wait queue.
> + * queue, marks it as ready (UVC_BUF_STATE_READY) and wakes its wait queue.
> * At that point, any process waiting on the buffer will be woken up. If a
> * process tries to dequeue a buffer after it has been marked ready, the
> * dequeing will succeed immediately.
> @@ -196,11 +196,12 @@
>
> switch (buf->state) {
> case UVC_BUF_STATE_ERROR:
> - case UVC_BUF_STATE_DONE:
> + case UVC_BUF_STATE_READY:
> v4l2_buf->flags |= V4L2_BUF_FLAG_DONE;
> break;
> case UVC_BUF_STATE_QUEUED:
> case UVC_BUF_STATE_ACTIVE:
> + case UVC_BUF_STATE_DONE:
> v4l2_buf->flags |= V4L2_BUF_FLAG_QUEUED;
> break;
> case UVC_BUF_STATE_IDLE:
> @@ -341,13 +342,14 @@
> uvc_trace(UVC_TRACE_CAPTURE, "[W] Corrupted data "
> "(transmission error).\n");
> ret = -EIO;
> - case UVC_BUF_STATE_DONE:
> + case UVC_BUF_STATE_READY:
> buf->state = UVC_BUF_STATE_IDLE;
> break;
>
> case UVC_BUF_STATE_IDLE:
> case UVC_BUF_STATE_QUEUED:
> case UVC_BUF_STATE_ACTIVE:
> + case UVC_BUF_STATE_DONE:
> default:
> uvc_trace(UVC_TRACE_CAPTURE, "[E] Invalid buffer state %u "
> "(driver bug?).\n", buf->state);
> @@ -383,7 +385,7 @@
> buf = list_first_entry(&queue->mainqueue, struct uvc_buffer, stream);
>
> poll_wait(file, &buf->wait, wait);
> - if (buf->state == UVC_BUF_STATE_DONE ||
> + if (buf->state == UVC_BUF_STATE_READY ||
> buf->state == UVC_BUF_STATE_ERROR)
> mask |= POLLIN | POLLRDNORM;
>
> @@ -489,6 +491,7 @@
>
> spin_lock_irqsave(&queue->irqlock, flags);
> list_del(&buf->queue);
> + buf->state = UVC_BUF_STATE_READY;
> if (!list_empty(&queue->irqqueue))
> nextbuf = list_first_entry(&queue->irqqueue, struct uvc_buffer,
> queue);
> diff -r c1f376eae978 linux/drivers/media/video/uvc/uvc_video.c
> --- a/linux/drivers/media/video/uvc/uvc_video.c Sat Dec 12 18:57:17 2009 +0100
> +++ b/linux/drivers/media/video/uvc/uvc_video.c Wed Dec 16 01:10:21 2009 +0100
> @@ -578,8 +578,7 @@
> uvc_video_decode_end(stream, buf, mem,
> urb->iso_frame_desc[i].actual_length);
>
> - if (buf->state == UVC_BUF_STATE_DONE ||
> - buf->state == UVC_BUF_STATE_ERROR)
> + if (buf->state == UVC_BUF_STATE_DONE)
> buf = uvc_queue_next_buffer(&stream->queue, buf);
> }
> }
> @@ -637,8 +636,7 @@
> if (!stream->bulk.skip_payload && buf != NULL) {
> uvc_video_decode_end(stream, buf, stream->bulk.header,
> stream->bulk.payload_size);
> - if (buf->state == UVC_BUF_STATE_DONE ||
> - buf->state == UVC_BUF_STATE_ERROR)
> + if (buf->state == UVC_BUF_STATE_DONE)
> buf = uvc_queue_next_buffer(&stream->queue,
> buf);
> }
> diff -r c1f376eae978 linux/drivers/media/video/uvc/uvcvideo.h
> --- a/linux/drivers/media/video/uvc/uvcvideo.h Sat Dec 12 18:57:17 2009 +0100
> +++ b/linux/drivers/media/video/uvc/uvcvideo.h Wed Dec 16 01:10:21 2009 +0100
> @@ -370,7 +370,8 @@
> UVC_BUF_STATE_QUEUED = 1,
> UVC_BUF_STATE_ACTIVE = 2,
> UVC_BUF_STATE_DONE = 3,
> - UVC_BUF_STATE_ERROR = 4,
> + UVC_BUF_STATE_READY = 4,
> + UVC_BUF_STATE_ERROR = 5,
> };
>
> struct uvc_buffer {
>
> --
> Regards,
>
> Laurent Pinchart
>
--
"Not possessing the gift of reflection, a dog does not know that he
does not know, and does not understand that he understands nothing;
we, on the other hand, are aware of both. If we behave otherwise, it
is from stupidity, or else from self-deception, to preserve our peace
of mind."
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