[v2,04/18] media/v4l2-core: set pages dirty upon releasing DMA buffers
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Message ID 20191103211813.213227-5-jhubbard@nvidia.com
State New
Headers show
Series
  • mm/gup: track dma-pinned pages: FOLL_PIN, FOLL_LONGTERM
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Commit Message

John Hubbard Nov. 3, 2019, 9:17 p.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.

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

Hans Verkuil Nov. 10, 2019, 10:10 a.m. UTC | #1
On 11/3/19 10:17 PM, 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.
> 
> Cc: Mauro Carvalho Chehab <mchehab@kernel.org>
> Signed-off-by: John Hubbard <jhubbard@nvidia.com>

Acked-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>

Looks good, thanks!

	Hans

> ---
>  drivers/media/v4l2-core/videobuf-dma-sg.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> 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;
>  	}
>
John Hubbard Nov. 11, 2019, 9:46 p.m. UTC | #2
On 11/10/19 2:10 AM, Hans Verkuil wrote:
> On 11/3/19 10:17 PM, 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.
>>
>> Cc: Mauro Carvalho Chehab <mchehab@kernel.org>
>> Signed-off-by: John Hubbard <jhubbard@nvidia.com>
> 
> Acked-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
> 
> Looks good, thanks!
> 

Hi Hans, it's great that you could take a look at this and the other v4l2 
patch, much appreciated.


thanks,

Patch
diff mbox series

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;
 	}