From: Michael Tretter m.tretter@pengutronix.de
[ Upstream commit 8d86a15649957c182e90fa2b1267c16699bc12f1 ]
When reaching the end of stream, V4L2 clients may expect the V4L2_EOS_EVENT before being able to dequeue the last buffer, which has the V4L2_BUF_FLAG_LAST flag set.
If the vb2_poll() function first checks for events and afterwards if buffers are available, a driver can queue the V4L2_EOS_EVENT event and return the buffer after the check for events but before the check for buffers. This causes vb2_poll() to signal that the buffer with V4L2_BUF_FLAG_LAST can be read without the V4L2_EOS_EVENT being available.
First, check for available buffers and afterwards for events to ensure that if vb2_poll() signals POLLIN | POLLRDNORM for the V4L2_BUF_FLAG_LAST buffer, it also signals POLLPRI for the V4L2_EOS_EVENT.
Signed-off-by: Michael Tretter m.tretter@pengutronix.de Signed-off-by: Hans Verkuil hverkuil-cisco@xs4all.nl Signed-off-by: Mauro Carvalho Chehab mchehab+samsung@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/media/common/videobuf2/videobuf2-v4l2.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-)
diff --git a/drivers/media/common/videobuf2/videobuf2-v4l2.c b/drivers/media/common/videobuf2/videobuf2-v4l2.c index 40d76eb4c2fe7..5a9ba3846f0a5 100644 --- a/drivers/media/common/videobuf2/videobuf2-v4l2.c +++ b/drivers/media/common/videobuf2/videobuf2-v4l2.c @@ -872,17 +872,19 @@ EXPORT_SYMBOL_GPL(vb2_queue_release); __poll_t vb2_poll(struct vb2_queue *q, struct file *file, poll_table *wait) { struct video_device *vfd = video_devdata(file); - __poll_t res = 0; + __poll_t res; + + res = vb2_core_poll(q, file, wait);
if (test_bit(V4L2_FL_USES_V4L2_FH, &vfd->flags)) { struct v4l2_fh *fh = file->private_data;
poll_wait(file, &fh->wait, wait); if (v4l2_event_pending(fh)) - res = EPOLLPRI; + res |= EPOLLPRI; }
- return res | vb2_core_poll(q, file, wait); + return res; } EXPORT_SYMBOL_GPL(vb2_poll);