Re: [PATCH 1/3] dma-buf/sync_file: cleanup fence merging a bit

[Daniel Vetter <daniel@ffwll.ch>]

On Tue, Apr 26, 2022 at 02:46:35PM +0200, Christian König wrote:
> krealloc_array() ignores attempts to reduce the array size, so the attempt
> to save memory is completely pointless here.
> 
> Also move testing for the no fence case into sync_file_set_fence(), this
> way we don't even touch the fence array when we don't have any fences.
> 
> Signed-off-by: Christian König <christian.koenig@amd.com>

Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>

> ---
>  drivers/dma-buf/sync_file.c | 21 +++++++--------------
>  1 file changed, 7 insertions(+), 14 deletions(-)
> 
> diff --git a/drivers/dma-buf/sync_file.c b/drivers/dma-buf/sync_file.c
> index 514d213261df..0fe564539166 100644
> --- a/drivers/dma-buf/sync_file.c
> +++ b/drivers/dma-buf/sync_file.c
> @@ -157,9 +157,15 @@ static int sync_file_set_fence(struct sync_file *sync_file,
>  	 * we already own a new reference to the fence. For num_fence > 1
>  	 * we own the reference of the dma_fence_array creation.
>  	 */
> -	if (num_fences == 1) {
> +
> +	if (num_fences == 0) {
> +		sync_file->fence = dma_fence_get_stub();
> +		kfree(fences);
> +
> +	} else if (num_fences == 1) {
>  		sync_file->fence = fences[0];
>  		kfree(fences);
> +
>  	} else {
>  		array = dma_fence_array_create(num_fences, fences,
>  					       dma_fence_context_alloc(1),
> @@ -261,19 +267,6 @@ static struct sync_file *sync_file_merge(const char *name, struct sync_file *a,
>  		}
>  	}
>  
> -	if (index == 0)
> -		fences[index++] = dma_fence_get_stub();
> -
> -	if (num_fences > index) {
> -		struct dma_fence **tmp;
> -
> -		/* Keep going even when reducing the size failed */
> -		tmp = krealloc_array(fences, index, sizeof(*fences),
> -				     GFP_KERNEL);
> -		if (tmp)
> -			fences = tmp;
> -	}
> -
>  	if (sync_file_set_fence(sync_file, fences, index) < 0)
>  		goto err_put_fences;
>  
> -- 
> 2.25.1
> 

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch