Re: [PATCH] videobuf2: call buf_finish() on unprocessed buffers

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Hi Jon,
There is a misunderstanding here. This patch will call buf_finish for
some buffers twice. A buffer does not get removed from queued_list
even if it is on the done_list. A buffer gets into the queued_list on
qbuf, gets into the done_list after an operation is finished and is
removed from both lists on dqbuf. This means that you shouldn't call
buf_finish for buffers on both lists, only for all buffers in the
queued_list, as it is a superset of both.
-- 
Best regards,
Pawel Osciak

On Thu, Jul 14, 2011 at 14:09, Jonathan Corbet <corbet@xxxxxxx> wrote:
> When user space stops streaming, there may be buffers which have been given
> to buf_prepare() and which may or may not have been passed to buf_queue().
> The videobuf2 core simply takes those buffers back; if buf_prepare() does
> work that needs cleaning up (like setting up a DMA mapping), that cleanup
> will not happen.
>
> This patch establishes a simple contract with drivers: buffers given to
> buf_prepare() will eventually see a buf_finish() call.
>
> Signed-off-by: Jonathan Corbet <corbet@xxxxxxx>
> ---
>  drivers/media/video/videobuf2-core.c |    8 +++++++-
>  1 files changed, 7 insertions(+), 1 deletions(-)
>
> diff --git a/drivers/media/video/videobuf2-core.c b/drivers/media/video/videobuf2-core.c
> index 6ba1461..2ba08ab 100644
> --- a/drivers/media/video/videobuf2-core.c
> +++ b/drivers/media/video/videobuf2-core.c
> @@ -1177,6 +1177,7 @@ EXPORT_SYMBOL_GPL(vb2_streamon);
>  */
>  static void __vb2_queue_cancel(struct vb2_queue *q)
>  {
> +       struct vb2_buffer *vb;
>        unsigned int i;
>
>        /*
> @@ -1188,13 +1189,18 @@ static void __vb2_queue_cancel(struct vb2_queue *q)
>        q->streaming = 0;
>
>        /*
> -        * Remove all buffers from videobuf's list...
> +        * Remove all buffers from videobuf's list...  Give the driver
> +        * a chance to clean them up first, though.
>         */
> +       list_for_each_entry(vb, &q->queued_list, queued_entry)
> +               call_qop(q, buf_finish, vb);
>        INIT_LIST_HEAD(&q->queued_list);
>        /*
>         * ...and done list; userspace will not receive any buffers it
>         * has not already dequeued before initiating cancel.
>         */
> +       list_for_each_entry(vb, &q->done_list, done_entry)
> +               call_qop(q, buf_finish, vb);
>        INIT_LIST_HEAD(&q->done_list);
>        wake_up_all(&q->done_wq);
>
> --
> 1.7.6
>
> --
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