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Commit ee2f8133 authored by Hans Verkuil's avatar Hans Verkuil Committed by Greg Kroah-Hartman
Browse files

media: videobuf2-core: dequeue if start_streaming fails 



[ Upstream commit c592b46907adbeb81243f7eb7a468c36692658b8 ]

If a vb2_queue sets q->min_buffers_needed then when the number of
queued buffers reaches q->min_buffers_needed, vb2_core_qbuf() will call
the start_streaming() callback. If start_streaming() returns an error,
then that error was just returned by vb2_core_qbuf(), but the buffer
was still queued. However, userspace expects that if VIDIOC_QBUF fails,
the buffer is returned dequeued.

So if start_streaming() fails, then remove the buffer from the queue,
thus avoiding this unwanted side-effect.

Signed-off-by: default avatarHans Verkuil <hverkuil-cisco@xs4all.nl>
Reviewed-by: default avatarLaurent Pinchart <laurent.pinchart@ideasonboard.com>
Tested-by: default avatarKieran Bingham <kieran.bingham@ideasonboard.com>
Fixes: b3379c62 ("[media] vb2: only call start_streaming if sufficient buffers are queued")
Signed-off-by: default avatarMauro Carvalho Chehab <mchehab+huawei@kernel.org>
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
parent 3377f2f8

drivers/media/common/videobuf2/videobuf2-core.c

+12 −1
Original line number Diff line number Diff line
@@ -1512,6 +1512,7 @@ int vb2_core_qbuf(struct vb2_queue *q, unsigned int index, void *pb, 
		  struct media_request *req)

{

	struct vb2_buffer *vb;

	enum vb2_buffer_state orig_state;

	int ret;



	if (q->error) {
@@ -1611,6 +1612,7 @@ int vb2_core_qbuf(struct vb2_queue *q, unsigned int index, void *pb, 
	 * Add to the queued buffers list, a buffer will stay on it until

	 * dequeued in dqbuf.

	 */

	orig_state = vb->state;

	list_add_tail(&vb->queued_entry, &q->queued_list);

	q->queued_count++;

	q->waiting_for_buffers = false;
@@ -1641,9 +1643,18 @@ int vb2_core_qbuf(struct vb2_queue *q, unsigned int index, void *pb, 
	if (q->streaming && !q->start_streaming_called &&

	    q->queued_count >= q->min_buffers_needed) {

		ret = vb2_start_streaming(q);

		if (ret)

		if (ret) {

			/*

			 * Since vb2_core_qbuf will return with an error,

			 * we should return it to state DEQUEUED since

			 * the error indicates that the buffer wasn't queued.

			 */

			list_del(&vb->queued_entry);

			q->queued_count--;

			vb->state = orig_state;

			return ret;

		}

	}



	dprintk(2, "qbuf of buffer %d succeeded\n", vb->index);

	return 0;