Re: [PATCH 1/4] dma-buf: add dma_fence_array_for_each (v2)

["Christian König" <ckoenig.leichtzumerken@gmail.com>]

Am 20.05.21 um 21:00 schrieb Jason Ekstrand:
> From: Christian König <ckoenig.leichtzumerken@gmail.com>
>
> Add a helper to iterate over all fences in a dma_fence_array object.
>
> v2 (Jason Ekstrand)
>   - Return NULL from dma_fence_array_first if head == NULL.  This matches
>     the iterator behavior of dma_fence_chain_for_each in that it iterates
>     zero times if head == NULL.
>   - Return NULL from dma_fence_array_next if index > array->num_fences.
>
> Signed-off-by: Jason Ekstrand <jason@jlekstrand.net>

Reviewed-by: Christian König <christian.koenig@amd.com>

BTW: I'm only seeing this patch from the series. Looks like somehow the 
rest didn't made it into my inbox.

> ---
>   drivers/dma-buf/dma-fence-array.c | 27 +++++++++++++++++++++++++++
>   include/linux/dma-fence-array.h   | 17 +++++++++++++++++
>   2 files changed, 44 insertions(+)
>
> diff --git a/drivers/dma-buf/dma-fence-array.c b/drivers/dma-buf/dma-fence-array.c
> index d3fbd950be944..2ac1afc697d0f 100644
> --- a/drivers/dma-buf/dma-fence-array.c
> +++ b/drivers/dma-buf/dma-fence-array.c
> @@ -201,3 +201,30 @@ bool dma_fence_match_context(struct dma_fence *fence, u64 context)
>   	return true;
>   }
>   EXPORT_SYMBOL(dma_fence_match_context);
> +
> +struct dma_fence *dma_fence_array_first(struct dma_fence *head)
> +{
> +	struct dma_fence_array *array;
> +
> +	if (!head)
> +		return NULL;
> +
> +	array = to_dma_fence_array(head);
> +	if (!array)
> +		return head;
> +
> +	return array->fences[0];
> +}
> +EXPORT_SYMBOL(dma_fence_array_first);
> +
> +struct dma_fence *dma_fence_array_next(struct dma_fence *head,
> +				       unsigned int index)
> +{
> +	struct dma_fence_array *array = to_dma_fence_array(head);
> +
> +	if (!array || index >= array->num_fences)
> +		return NULL;
> +
> +	return array->fences[index];
> +}
> +EXPORT_SYMBOL(dma_fence_array_next);
> diff --git a/include/linux/dma-fence-array.h b/include/linux/dma-fence-array.h
> index 303dd712220fd..588ac8089dd61 100644
> --- a/include/linux/dma-fence-array.h
> +++ b/include/linux/dma-fence-array.h
> @@ -74,6 +74,19 @@ to_dma_fence_array(struct dma_fence *fence)
>   	return container_of(fence, struct dma_fence_array, base);
>   }
>   
> +/**
> + * dma_fence_array_for_each - iterate over all fences in array
> + * @fence: current fence
> + * @index: index into the array
> + * @head: potential dma_fence_array object
> + *
> + * Test if @array is a dma_fence_array object and if yes iterate over all fences
> + * in the array. If not just iterate over the fence in @array itself.
> + */
> +#define dma_fence_array_for_each(fence, index, head)			\
> +	for (index = 0, fence = dma_fence_array_first(head); fence;	\
> +	     ++(index), fence = dma_fence_array_next(head, index))
> +
>   struct dma_fence_array *dma_fence_array_create(int num_fences,
>   					       struct dma_fence **fences,
>   					       u64 context, unsigned seqno,
> @@ -81,4 +94,8 @@ struct dma_fence_array *dma_fence_array_create(int num_fences,
>   
>   bool dma_fence_match_context(struct dma_fence *fence, u64 context);
>   
> +struct dma_fence *dma_fence_array_first(struct dma_fence *head);
> +struct dma_fence *dma_fence_array_next(struct dma_fence *head,
> +				       unsigned int index);
> +
>   #endif /* __LINUX_DMA_FENCE_ARRAY_H */