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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