This is a note to let you know that I've just added the patch titled
media: vb2: fix VBI/poll regression
to the 3.16-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
media-vb2-fix-vbi-poll-regression.patch
and it can be found in the queue-3.16 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 58d75f4b1ce26324b4d809b18f94819843a98731 Mon Sep 17 00:00:00 2001
From: Hans Verkuil <hans.verkuil@xxxxxxxxx>
Date: Sat, 20 Sep 2014 16:16:35 -0300
Subject: media: vb2: fix VBI/poll regression
From: Hans Verkuil <hans.verkuil@xxxxxxxxx>
commit 58d75f4b1ce26324b4d809b18f94819843a98731 upstream.
The recent conversion of saa7134 to vb2 unconvered a poll() bug that
broke the teletext applications alevt and mtt. These applications
expect that calling poll() without having called VIDIOC_STREAMON will
cause poll() to return POLLERR. That did not happen in vb2.
This patch fixes that behavior. It also fixes what should happen when
poll() is called when STREAMON is called but no buffers have been
queued. In that case poll() will also return POLLERR, but only for
capture queues since output queues will always return POLLOUT
anyway in that situation.
This brings the vb2 behavior in line with the old videobuf behavior.
Signed-off-by: Hans Verkuil <hans.verkuil@xxxxxxxxx>
Acked-by: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>
Signed-off-by: Mauro Carvalho Chehab <mchehab@xxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/media/v4l2-core/videobuf2-core.c | 15 +++++++++++++--
include/media/videobuf2-core.h | 4 ++++
2 files changed, 17 insertions(+), 2 deletions(-)
--- a/drivers/media/v4l2-core/videobuf2-core.c
+++ b/drivers/media/v4l2-core/videobuf2-core.c
@@ -967,6 +967,7 @@ static int __reqbufs(struct vb2_queue *q
* to the userspace.
*/
req->count = allocated_buffers;
+ q->waiting_for_buffers = !V4L2_TYPE_IS_OUTPUT(q->type);
return 0;
}
@@ -1014,6 +1015,7 @@ static int __create_bufs(struct vb2_queu
memset(q->plane_sizes, 0, sizeof(q->plane_sizes));
memset(q->alloc_ctx, 0, sizeof(q->alloc_ctx));
q->memory = create->memory;
+ q->waiting_for_buffers = !V4L2_TYPE_IS_OUTPUT(q->type);
}
num_buffers = min(create->count, VIDEO_MAX_FRAME - q->num_buffers);
@@ -1812,6 +1814,7 @@ static int vb2_internal_qbuf(struct vb2_
*/
list_add_tail(&vb->queued_entry, &q->queued_list);
q->queued_count++;
+ q->waiting_for_buffers = false;
vb->state = VB2_BUF_STATE_QUEUED;
if (V4L2_TYPE_IS_OUTPUT(q->type)) {
/*
@@ -2244,6 +2247,7 @@ static int vb2_internal_streamoff(struct
* their normal dequeued state.
*/
__vb2_queue_cancel(q);
+ q->waiting_for_buffers = !V4L2_TYPE_IS_OUTPUT(q->type);
dprintk(3, "successful\n");
return 0;
@@ -2562,9 +2566,16 @@ unsigned int vb2_poll(struct vb2_queue *
}
/*
- * There is nothing to wait for if no buffers have already been queued.
+ * There is nothing to wait for if the queue isn't streaming.
*/
- if (list_empty(&q->queued_list))
+ if (!vb2_is_streaming(q))
+ return res | POLLERR;
+ /*
+ * For compatibility with vb1: if QBUF hasn't been called yet, then
+ * return POLLERR as well. This only affects capture queues, output
+ * queues will always initialize waiting_for_buffers to false.
+ */
+ if (q->waiting_for_buffers)
return res | POLLERR;
if (list_empty(&q->done_list))
--- a/include/media/videobuf2-core.h
+++ b/include/media/videobuf2-core.h
@@ -375,6 +375,9 @@ struct v4l2_fh;
* @streaming: current streaming state
* @start_streaming_called: start_streaming() was called successfully and we
* started streaming.
+ * @waiting_for_buffers: used in poll() to check if vb2 is still waiting for
+ * buffers. Only set for capture queues if qbuf has not yet been
+ * called since poll() needs to return POLLERR in that situation.
* @fileio: file io emulator internal data, used only if emulator is active
* @threadio: thread io internal data, used only if thread is active
*/
@@ -411,6 +414,7 @@ struct vb2_queue {
unsigned int streaming:1;
unsigned int start_streaming_called:1;
+ unsigned int waiting_for_buffers:1;
struct vb2_fileio_data *fileio;
struct vb2_threadio_data *threadio;
Patches currently in stable-queue which might be from hans.verkuil@xxxxxxxxx are
queue-3.16/media-vb2-fix-vbi-poll-regression.patch
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