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authorHans Verkuil <hverkuil-cisco@xs4all.nl>2021-06-30 09:58:23 +0200
committerMauro Carvalho Chehab <mchehab+huawei@kernel.org>2021-07-30 13:01:03 +0200
commitc592b46907adbeb81243f7eb7a468c36692658b8 (patch)
tree3d0a70b8779e798f5d2fa9a236953121d5318cfe
parent76f22c93b209c811bd489950f17f8839adb31901 (diff)
media: videobuf2-core: dequeue if start_streaming fails
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: Hans Verkuil <hverkuil-cisco@xs4all.nl> Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Tested-by: Kieran Bingham <kieran.bingham@ideasonboard.com> Fixes: b3379c6201bb ("[media] vb2: only call start_streaming if sufficient buffers are queued") Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
-rw-r--r--drivers/media/common/videobuf2/videobuf2-core.c13
1 files changed, 12 insertions, 1 deletions
diff --git a/drivers/media/common/videobuf2/videobuf2-core.c b/drivers/media/common/videobuf2/videobuf2-core.c
index 02281d13505f..508ac295eb06 100644
--- a/drivers/media/common/videobuf2/videobuf2-core.c
+++ b/drivers/media/common/videobuf2/videobuf2-core.c
@@ -1573,6 +1573,7 @@ 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) {
@@ -1673,6 +1674,7 @@ 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;
@@ -1703,8 +1705,17 @@ 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(q, 2, "qbuf of buffer %d succeeded\n", vb->index);