linux-kernel - [PATCH 3.16 241/254] vb2: V4L2_BUF_FLAG

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Message-ID: <lsq.1519831218.561298105@decadent.org.uk>
Date:   Wed, 28 Feb 2018 15:20:18 +0000
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org,
        "Mauro Carvalho Chehab" <mchehab@...pensource.com>,
        "Hans Verkuil" <hans.verkuil@...co.com>,
        "Ricardo Ribalda" <ricardo.ribalda@...il.com>,
        "Dimitrios Katsaros" <patcherwork@...il.com>
Subject: [PATCH 3.16 241/254] vb2: V4L2_BUF_FLAG_DONE is set after DQBUF

3.16.55-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Ricardo Ribalda <ricardo.ribalda@...il.com>

commit 3171cc2b4eb9831ab4df1d80d0410a945b8bc84e upstream.

According to the doc, V4L2_BUF_FLAG_DONE is cleared after DQBUF:

V4L2_BUF_FLAG_DONE 0x00000004  ... After calling the VIDIOC_QBUF or
VIDIOC_DQBUF it is always cleared ...

Unfortunately, it seems that videobuf2 keeps it set after DQBUF. This
can be tested with vivid and dev_debug:

[257604.338082] video1: VIDIOC_DQBUF: 71:33:25.00260479 index=3,
type=vid-cap, flags=0x00002004, field=none, sequence=163,
memory=userptr, bytesused=460800, offset/userptr=0x344b000,
length=460800

This patch forces FLAG_DONE to 0 after calling DQBUF.

Reported-by: Dimitrios Katsaros <patcherwork@...il.com>
Signed-off-by: Ricardo Ribalda Delgado <ricardo.ribalda@...il.com>
Signed-off-by: Hans Verkuil <hans.verkuil@...co.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@...pensource.com>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 drivers/media/v4l2-core/videobuf2-core.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/media/v4l2-core/videobuf2-core.c b/drivers/media/v4l2-core/videobuf2-core.c
index e63a7904bf5b..ee8b697972bb 100644
--- a/drivers/media/v4l2-core/videobuf2-core.c
+++ b/drivers/media/v4l2-core/videobuf2-core.c
@@ -2069,6 +2069,11 @@ static int vb2_internal_dqbuf(struct vb2_queue *q, struct v4l2_buffer *b, bool n
 	dprintk(1, "dqbuf of buffer %d, with state %d\n",
 			vb->v4l2_buf.index, vb->state);
 
+	/*
+	 * After calling the VIDIOC_DQBUF V4L2_BUF_FLAG_DONE must be
+	 * cleared.
+	 */
+	b->flags &= ~V4L2_BUF_FLAG_DONE;
 	return 0;
 }