diff mbox series

[v7,08/24] media/v4l2-core: set pages dirty upon releasing DMA buffers

Message ID 20191121071354.456618-9-jhubbard@nvidia.com (mailing list archive)
State New, archived
Headers show
Series mm/gup: track dma-pinned pages: FOLL_PIN | expand

Commit Message

John Hubbard Nov. 21, 2019, 7:13 a.m. UTC 
After DMA is complete, and the device and CPU caches are synchronized,
it's still required to mark the CPU pages as dirty, if the data was
coming from the device. However, this driver was just issuing a
bare put_page() call, without any set_page_dirty*() call.

Fix the problem, by calling set_page_dirty_lock() if the CPU pages
were potentially receiving data from the device.

Acked-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Cc: Mauro Carvalho Chehab <mchehab@kernel.org>
Signed-off-by: John Hubbard <jhubbard@nvidia.com>
---
 drivers/media/v4l2-core/videobuf-dma-sg.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

Comments

Christoph Hellwig Nov. 21, 2019, 8:09 a.m. UTC | #1 
On Wed, Nov 20, 2019 at 11:13:38PM -0800, John Hubbard wrote:
> After DMA is complete, and the device and CPU caches are synchronized,
> it's still required to mark the CPU pages as dirty, if the data was
> coming from the device. However, this driver was just issuing a
> bare put_page() call, without any set_page_dirty*() call.
> 
> Fix the problem, by calling set_page_dirty_lock() if the CPU pages
> were potentially receiving data from the device.

Looks good, and like a fix that should be queued up through the media
tree for 5.5 and maybe even added to -stable.

Reviewed-by: Christoph Hellwig <hch@lst.de>
diff mbox series

Patch

diff --git a/drivers/media/v4l2-core/videobuf-dma-sg.c b/drivers/media/v4l2-core/videobuf-dma-sg.c
index 66a6c6c236a7..28262190c3ab 100644
--- a/drivers/media/v4l2-core/videobuf-dma-sg.c
+++ b/drivers/media/v4l2-core/videobuf-dma-sg.c
@@ -349,8 +349,11 @@  int videobuf_dma_free(struct videobuf_dmabuf *dma)
 	BUG_ON(dma->sglen);
 
 	if (dma->pages) {
-		for (i = 0; i < dma->nr_pages; i++)
+		for (i = 0; i < dma->nr_pages; i++) {
+			if (dma->direction == DMA_FROM_DEVICE)
+				set_page_dirty_lock(dma->pages[i]);
 			put_page(dma->pages[i]);
+		}
 		kfree(dma->pages);
 		dma->pages = NULL;
 	}