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From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: stable@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	patches@lists.linux.dev,
	Vladimir Zapolskiy <vladimir.zapolskiy@linaro.org>,
	Robert Foss <robert.foss@linaro.org>,
	Hans Verkuil <hverkuil-cisco@xs4all.nl>,
	Mauro Carvalho Chehab <mchehab@kernel.org>,
	Sasha Levin <sashal@kernel.org>
Subject: [PATCH 4.19 099/521] media: camss: Clean up received buffers on failed start of streaming
Date: Mon, 16 Jan 2023 16:46:01 +0100
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From: Vladimir Zapolskiy <vladimir.zapolskiy@linaro.org>

[ Upstream commit c8f3582345e6a69da65ab588f7c4c2d1685b0e80 ]

It is required to return the received buffers, if streaming can not be
started. For instance media_pipeline_start() may fail with EPIPE, if
a link validation between entities is not passed, and in such a case
a user gets a kernel warning:

  WARNING: CPU: 1 PID: 520 at drivers/media/common/videobuf2/videobuf2-core.c:1592 vb2_start_streaming+0xec/0x160
  <snip>
  Call trace:
   vb2_start_streaming+0xec/0x160
   vb2_core_streamon+0x9c/0x1a0
   vb2_ioctl_streamon+0x68/0xbc
   v4l_streamon+0x30/0x3c
   __video_do_ioctl+0x184/0x3e0
   video_usercopy+0x37c/0x7b0
   video_ioctl2+0x24/0x40
   v4l2_ioctl+0x4c/0x70

The fix is to correct the error path in video_start_streaming() of camss.

Fixes: 0ac2586c410f ("media: camss: Add files which handle the video device nodes")
Signed-off-by: Vladimir Zapolskiy <vladimir.zapolskiy@linaro.org>
Reviewed-by: Robert Foss <robert.foss@linaro.org>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/media/platform/qcom/camss/camss-video.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/media/platform/qcom/camss/camss-video.c b/drivers/media/platform/qcom/camss/camss-video.c
index e81ebeb0506e..23701ec8d7de 100644
--- a/drivers/media/platform/qcom/camss/camss-video.c
+++ b/drivers/media/platform/qcom/camss/camss-video.c
@@ -438,7 +438,7 @@ static int video_start_streaming(struct vb2_queue *q, unsigned int count)
 
 	ret = media_pipeline_start(&vdev->entity, &video->pipe);
 	if (ret < 0)
-		return ret;
+		goto flush_buffers;
 
 	ret = video_check_format(video);
 	if (ret < 0)
@@ -467,6 +467,7 @@ static int video_start_streaming(struct vb2_queue *q, unsigned int count)
 error:
 	media_pipeline_stop(&vdev->entity);
 
+flush_buffers:
 	video->ops->flush_buffers(video, VB2_BUF_STATE_QUEUED);
 
 	return ret;
-- 
2.35.1