[RFC 11/11] vb2: dma-contig: Add WARN_ON_ONCE() to check for potential bugs

[Sakari Ailus <sakari.ailus@linux.intel.com>]

The scatterlist should always be present when the cache would need to be
flushed. Each buffer type has its own means to provide that. Add
WARN_ON_ONCE() to check the scatterist exists.

Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
---
 drivers/media/v4l2-core/videobuf2-dma-contig.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/media/v4l2-core/videobuf2-dma-contig.c b/drivers/media/v4l2-core/videobuf2-dma-contig.c
index 65ee122..58c35c5 100644
--- a/drivers/media/v4l2-core/videobuf2-dma-contig.c
+++ b/drivers/media/v4l2-core/videobuf2-dma-contig.c
@@ -145,6 +145,9 @@ static void vb2_dc_prepare(void *buf_priv)
 	    !dma_get_attr(DMA_ATTR_NON_CONSISTENT, buf->attrs))
 		return;
 
+	if (WARN_ON_ONCE(!sgt))
+		return;
+
 	dma_sync_sg_for_device(buf->dev, sgt->sgl, sgt->nents, buf->dma_dir);
 }
 
@@ -161,6 +164,9 @@ static void vb2_dc_finish(void *buf_priv)
 	    !dma_get_attr(DMA_ATTR_NON_CONSISTENT, buf->attrs))
 		return;
 
+	if (WARN_ON_ONCE(!sgt))
+		return;
+
 	dma_sync_sg_for_cpu(buf->dev, sgt->sgl, sgt->nents, buf->dma_dir);
 }
 
-- 
2.1.0.231.g7484e3b