[PATCH 6/6] media: sun4i-csi: 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.

sun4i_csi_start_streaming() returned -EINVAL when no matching CSI
format could be found, before any setup (scratch buffer allocation,
pipeline start) had been performed.  The remaining error paths already
converge on the err_clear_dma_queue label, which calls
return_all_buffers(..., VB2_BUF_STATE_QUEUED) under csi->qlock.  Jump
to that label directly: the intermediate err_disable_device /
err_disable_pipeline / err_free_scratch_buffer 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: 577bbf23b758 ("media: sunxi: Add A10 CSI driver")
Cc: stable at vger.kernel.org
Signed-off-by: Valery Borovsky <vebohr at gmail.com>
---
 drivers/media/platform/sunxi/sun4i-csi/sun4i_dma.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/media/platform/sunxi/sun4i-csi/sun4i_dma.c b/drivers/media/platform/sunxi/sun4i-csi/sun4i_dma.c
index e911c7f7acc5..4781db21c205 100644
--- a/drivers/media/platform/sunxi/sun4i-csi/sun4i_dma.c
+++ b/drivers/media/platform/sunxi/sun4i-csi/sun4i_dma.c
@@ -234,8 +234,10 @@ static int sun4i_csi_start_streaming(struct vb2_queue *vq, unsigned int count)
 	int ret;
 
 	csi_fmt = sun4i_csi_find_format(&csi->fmt.pixelformat, NULL);
-	if (!csi_fmt)
-		return -EINVAL;
+	if (!csi_fmt) {
+		ret = -EINVAL;
+		goto err_clear_dma_queue;
+	}
 
 	dev_dbg(csi->dev, "Starting capture\n");
 
-- 
2.51.0