Commit 7708065f authored by Michael Tretter's avatar Michael Tretter Committed by Mauro Carvalho Chehab
Browse files

media: v4l2-mem2mem: reorder checks in v4l2_m2m_poll() 



When reaching the end of stream, V4L2 m2m clients may expect the
V4L2_EOS_EVENT. Although the V4L2_EOS_EVENT is deprecated behavior,
drivers must signal that event before dequeuing the buffer that has the
V4L2_BUF_FLAG_LAST flag set.

If a driver queues the V4L2_EOS_EVENT event and returns the buffer after
the check for events but before the check for buffers, vb2_m2m_poll()
will signal that the buffer with V4L2_BUF_FLAG_LAST can be read but not
that the V4L2_EOS_EVENT is available.

Split the check for buffers into a separate function and check for
available buffers before checking for events. This ensures that if
vb2_m2m_poll() signals POLLIN | POLLRDNORM for the V4L2_BUF_FLAG_LAST
buffer, it signals POLLPRI for the V4L2_EOS_EVENT, too.

Signed-off-by: default avatarMichael Tretter <m.tretter@pengutronix.de>
Signed-off-by: default avatarHans Verkuil <hverkuil-cisco@xs4all.nl>
[hverkuil-cisco@xs4all.nl: fix checkpatch alignment warning]
Signed-off-by: default avatarMauro Carvalho Chehab <mchehab+samsung@kernel.org>
parent 8d86a156

drivers/media/v4l2-core/v4l2-mem2mem.c

+27 −20
Original line number Diff line number Diff line
@@ -603,11 +603,10 @@ int v4l2_m2m_streamoff(struct file *file, struct v4l2_m2m_ctx *m2m_ctx, 
}

EXPORT_SYMBOL_GPL(v4l2_m2m_streamoff);



__poll_t v4l2_m2m_poll(struct file *file, struct v4l2_m2m_ctx *m2m_ctx,

static __poll_t v4l2_m2m_poll_for_data(struct file *file,

				       struct v4l2_m2m_ctx *m2m_ctx,

				       struct poll_table_struct *wait)

{

	struct video_device *vfd = video_devdata(file);

	__poll_t req_events = poll_requested_events(wait);

	struct vb2_queue *src_q, *dst_q;

	struct vb2_buffer *src_vb = NULL, *dst_vb = NULL;

	__poll_t rc = 0;
@@ -619,16 +618,6 @@ __poll_t v4l2_m2m_poll(struct file *file, struct v4l2_m2m_ctx *m2m_ctx, 
	poll_wait(file, &src_q->done_wq, wait);

	poll_wait(file, &dst_q->done_wq, 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))

			rc = EPOLLPRI;

		if (!(req_events & (EPOLLOUT | EPOLLWRNORM | EPOLLIN | EPOLLRDNORM)))

			return rc;

	}



	/*

	 * There has to be at least one buffer queued on each queued_list, which

	 * means either in driver already or waiting for driver to claim it
@@ -637,10 +626,8 @@ __poll_t v4l2_m2m_poll(struct file *file, struct v4l2_m2m_ctx *m2m_ctx, 
	if ((!src_q->streaming || src_q->error ||

	     list_empty(&src_q->queued_list)) &&

	    (!dst_q->streaming || dst_q->error ||

	     list_empty(&dst_q->queued_list))) {

		rc |= EPOLLERR;

		goto end;

	}

	     list_empty(&dst_q->queued_list)))

		return EPOLLERR;



	spin_lock_irqsave(&dst_q->done_lock, flags);

	if (list_empty(&dst_q->done_list)) {
@@ -650,7 +637,7 @@ __poll_t v4l2_m2m_poll(struct file *file, struct v4l2_m2m_ctx *m2m_ctx, 
		 */

		if (dst_q->last_buffer_dequeued) {

			spin_unlock_irqrestore(&dst_q->done_lock, flags);

			return rc | EPOLLIN | EPOLLRDNORM;

			return EPOLLIN | EPOLLRDNORM;

		}

	}

	spin_unlock_irqrestore(&dst_q->done_lock, flags);
@@ -673,7 +660,27 @@ __poll_t v4l2_m2m_poll(struct file *file, struct v4l2_m2m_ctx *m2m_ctx, 
		rc |= EPOLLIN | EPOLLRDNORM;

	spin_unlock_irqrestore(&dst_q->done_lock, flags);



end:

	return rc;

}



__poll_t v4l2_m2m_poll(struct file *file, struct v4l2_m2m_ctx *m2m_ctx,

		       struct poll_table_struct *wait)

{

	struct video_device *vfd = video_devdata(file);

	__poll_t req_events = poll_requested_events(wait);

	__poll_t rc = 0;



	if (req_events & (EPOLLOUT | EPOLLWRNORM | EPOLLIN | EPOLLRDNORM))

		rc = v4l2_m2m_poll_for_data(file, m2m_ctx, 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))

			rc |= EPOLLPRI;

	}



	return rc;

}

EXPORT_SYMBOL_GPL(v4l2_m2m_poll);