[PATCH 5/6] media: stm32-dcmipp: Return queued buffers on start_streaming() failure

[Valery Borovsky]

The vb2 framework hands buffers to the driver via buf_queue() before
calling start_streaming().  If start_streaming() returns an error
without first returning those buffers via vb2_buffer_done(),
vb2_start_streaming() fires WARN_ON(owned_by_drv_count) and the queued
buffers leak.

dcmipp_bytecap_start_streaming() returned -EINVAL when the source
subdevice could not be resolved from the media graph, before
pm_runtime_resume_and_get() and media_pipeline_start() had been called.
The remaining error paths already converge on the err_buffer_done
label, which calls dcmipp_bytecap_all_buffers_done(...,
VB2_BUF_STATE_QUEUED).  Jump to that label directly: the intermediate
err_pm_put / err_media_pipeline_stop labels are skipped, which is
correct because nothing they would undo has happened yet.

This mirrors the uvcvideo fix in commit 4cf3b6fd54eb ("media: uvcvideo:
Return queued buffers on start_streaming() failure").

Fixes: 28e0f3772296 ("media: stm32-dcmipp: STM32 DCMIPP camera interface driver")
Cc: stable at vger.kernel.org
Signed-off-by: Valery Borovsky <vebohr at gmail.com>
---
 .../media/platform/st/stm32/stm32-dcmipp/dcmipp-bytecap.c   | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/media/platform/st/stm32/stm32-dcmipp/dcmipp-bytecap.c b/drivers/media/platform/st/stm32/stm32-dcmipp/dcmipp-bytecap.c
index a42f43d19f9e..f0e809458489 100644
--- a/drivers/media/platform/st/stm32/stm32-dcmipp/dcmipp-bytecap.c
+++ b/drivers/media/platform/st/stm32/stm32-dcmipp/dcmipp-bytecap.c
@@ -401,8 +401,10 @@ static int dcmipp_bytecap_start_streaming(struct vb2_queue *vq,
 	 */
 	if (!vcap->s_subdev) {
 		pad = media_pad_remote_pad_first(&vcap->vdev.entity.pads[0]);
-		if (!pad || !is_media_entity_v4l2_subdev(pad->entity))
-			return -EINVAL;
+		if (!pad || !is_media_entity_v4l2_subdev(pad->entity)) {
+			ret = -EINVAL;
+			goto err_buffer_done;
+		}
 		vcap->s_subdev = media_entity_to_v4l2_subdev(pad->entity);
 		vcap->s_subdev_pad_nb = pad->index;
 	}
-- 
2.51.0