[PATCH v4] dmaengine: sun6i-dma: Fix memory leak in sun6i_dma_terminate_all

[Vinod Koul]

On 18-06-26, 10:06, Hongling Zeng wrote:
> When terminating DMA transfers, active descriptors are not properly
> reclaimed. Only cyclic descriptors were handled, leaving non-cyclic
> descriptors and their LLI chains to be permanently leaked.
> 
> Fix by using vchan_terminate_vdesc() which handles both cyclic and
> non-cyclic descriptors by adding them to desc_terminated queue for
> proper cleanup.
> 
> Add pchan->desc != pchan->done check to prevent double-adding completed
> descriptors, which would corrupt the list.

Thanks for the patch. Please consider revising the subject which should
describe the changes in the patch and not the fix/issue.

A better one would be "fix reclaim descriptors while terminating"

> 
> Fixes: 555859308723 ("dmaengine: sun6i: Add driver for the Allwinner A31 DMA controller")
> Signed-off-by: Hongling Zeng <zenghongling at kylinos.cn>
> Acked-by: Jernej Skrabec <jernej.skrabec at gmail.com>
> Suggested-by: Frank Li <Frank.li at oss.nxp.com>
> 
> ---
>  Change in v2;
>  -Add pchan->desc != pchan->done check to prevent race condition
>   where completed descriptors could be double-added to desc_completed
>   list, causing list corruption
> ---
>  Change in v3:
>  -Fix by using vchan_terminate_vdesc() as suggested by Frank Li
> ---
>  Change in v4:
>  -Correct the commit message
> ---
>  drivers/dma/sun6i-dma.c | 13 +++++--------
>  1 file changed, 5 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/dma/sun6i-dma.c b/drivers/dma/sun6i-dma.c
> index 7a79f346250a..134ae840f176 100644
> --- a/drivers/dma/sun6i-dma.c
> +++ b/drivers/dma/sun6i-dma.c
> @@ -946,16 +946,13 @@ static int sun6i_dma_terminate_all(struct dma_chan *chan)
>  
>  	spin_lock_irqsave(&vchan->vc.lock, flags);
>  
> -	if (vchan->cyclic) {
> -		vchan->cyclic = false;
> -		if (pchan && pchan->desc) {
> -			struct virt_dma_desc *vd = &pchan->desc->vd;
> -			struct virt_dma_chan *vc = &vchan->vc;
> -
> -			list_add_tail(&vd->node, &vc->desc_completed);
> -		}
> +	if (pchan && pchan->desc && pchan->desc != pchan->done) {
> +		struct virt_dma_desc *vd = &pchan->desc->vd;
> +		
> +		vchan_terminate_vdesc(vd);
>  	}
>  
> +	vchan->cyclic = false;
>  	vchan_get_all_descriptors(&vchan->vc, &head);
>  
>  	if (pchan) {
> -- 
> 2.25.1

-- 
~Vinod