linux-kernel - [PATCH 3.16 256/305] media: vb2: don't call __vb2_queue_cancel if vb2_start

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Message-ID: <lsq.1549201508.469608874@decadent.org.uk>
Date:   Sun, 03 Feb 2019 14:45:08 +0100
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, Denis Kirjanov <kda@...ux-powerpc.org>,
        "Hans Verkuil" <hverkuil-cisco@...all.nl>,
        "Sakari Ailus" <sakari.ailus@...ux.intel.com>,
        "Mauro Carvalho Chehab" <mchehab+samsung@...nel.org>
Subject: [PATCH 3.16 256/305] media: vb2: don't call __vb2_queue_cancel if
 vb2_start_streaming failed

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

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

From: Hans Verkuil <hverkuil-cisco@...all.nl>

commit 04990215dec43c424daff00d1f622167b8aafd1f upstream.

vb2_start_streaming() already rolls back the buffers, so there is no
need to call __vb2_queue_cancel(). Especially since __vb2_queue_cancel()
does too much, such as zeroing the q->queued_count value, causing vb2
to think that no buffers have been queued.

It appears that this call to __vb2_queue_cancel() is a left-over from
before commit b3379c6201bb3.

Fixes: b3379c6201bb3 ('vb2: only call start_streaming if sufficient buffers are queued')

Signed-off-by: Hans Verkuil <hverkuil-cisco@...all.nl>
Acked-by: Sakari Ailus <sakari.ailus@...ux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@...nel.org>
[bwh: Backported to 3.16: adjust filename, context]
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 drivers/media/v4l2-core/videobuf2-core.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

--- a/drivers/media/v4l2-core/videobuf2-core.c
+++ b/drivers/media/v4l2-core/videobuf2-core.c
@@ -2200,10 +2200,8 @@ static int vb2_internal_streamon(struct
 	 */
 	if (q->queued_count >= q->min_buffers_needed) {
 		ret = vb2_start_streaming(q);
-		if (ret) {
-			__vb2_queue_cancel(q);
+		if (ret)
 			return ret;
-		}
 	}
 
 	q->streaming = 1;