Re: [PATCH v2 1/2] dma-buf: Split out dma fence array create into alloc and arm functions

["Christian König" <christian.koenig@amd.com>]

Am 26.08.24 um 21:23 schrieb Matthew Brost:
> On Mon, Aug 26, 2024 at 07:57:07PM +0200, Christian König wrote:
>> Am 26.08.24 um 19:01 schrieb Matthew Brost:
>>> Useful to preallocate dma fence array and then arm in path of reclaim or
>>> a dma fence.
>>>
>>> v2:
>>>    - s/arm/init (Christian)
>>>    - Drop !array warn (Christian)
>>>
>>> Cc: Sumit Semwal <sumit.semwal@linaro.org>
>>> Cc: Christian König <christian.koenig@amd.com>
>>> Signed-off-by: Matthew Brost <matthew.brost@intel.com>
>> Reviewed-by: Christian König <christian.koenig@amd.com>
> Thanks for the review.
>
> Unfamilar with the merge flows to dma-buf subsystem. Do you merge this
> into a dma-buf branch that we can then pick up in 6.12?

I can push the patches into drm-misc-next or alternatively you pick them 
up through an XE branch.

The change to the dma_fence_array is small enough that it probably won't 
cause any conflict, so both approaches works for me.

Christian.

>
> Matt
>
>>> ---
>>>    drivers/dma-buf/dma-fence-array.c | 78 ++++++++++++++++++++++---------
>>>    include/linux/dma-fence-array.h   |  6 +++
>>>    2 files changed, 63 insertions(+), 21 deletions(-)
>>>
>>> diff --git a/drivers/dma-buf/dma-fence-array.c b/drivers/dma-buf/dma-fence-array.c
>>> index c74ac197d5fe..0659e6b29b3c 100644
>>> --- a/drivers/dma-buf/dma-fence-array.c
>>> +++ b/drivers/dma-buf/dma-fence-array.c
>>> @@ -144,37 +144,38 @@ const struct dma_fence_ops dma_fence_array_ops = {
>>>    EXPORT_SYMBOL(dma_fence_array_ops);
>>>    /**
>>> - * dma_fence_array_create - Create a custom fence array
>>> + * dma_fence_array_alloc - Allocate a custom fence array
>>> + * @num_fences:		[in]	number of fences to add in the array
>>> + *
>>> + * Return dma fence array on success, NULL on failure
>>> + */
>>> +struct dma_fence_array *dma_fence_array_alloc(int num_fences)
>>> +{
>>> +	struct dma_fence_array *array;
>>> +
>>> +	return kzalloc(struct_size(array, callbacks, num_fences), GFP_KERNEL);
>>> +}
>>> +EXPORT_SYMBOL(dma_fence_array_alloc);
>>> +
>>> +/**
>>> + * dma_fence_array_init - Arm a custom fence array
>>> + * @array:		[in]	dma fence array to arm
>>>     * @num_fences:		[in]	number of fences to add in the array
>>>     * @fences:		[in]	array containing the fences
>>>     * @context:		[in]	fence context to use
>>>     * @seqno:		[in]	sequence number to use
>>>     * @signal_on_any:	[in]	signal on any fence in the array
>>>     *
>>> - * Allocate a dma_fence_array object and initialize the base fence with
>>> - * dma_fence_init().
>>> - * In case of error it returns NULL.
>>> - *
>>> - * The caller should allocate the fences array with num_fences size
>>> - * and fill it with the fences it wants to add to the object. Ownership of this
>>> - * array is taken and dma_fence_put() is used on each fence on release.
>>> - *
>>> - * If @signal_on_any is true the fence array signals if any fence in the array
>>> - * signals, otherwise it signals when all fences in the array signal.
>>> + * Implementation of @dma_fence_array_create without allocation. Useful to arm a
>>> + * preallocated dma fence fence in the path of reclaim or dma fence signaling.
>>>     */
>>> -struct dma_fence_array *dma_fence_array_create(int num_fences,
>>> -					       struct dma_fence **fences,
>>> -					       u64 context, unsigned seqno,
>>> -					       bool signal_on_any)
>>> +void dma_fence_array_init(struct dma_fence_array *array,
>>> +			  int num_fences, struct dma_fence **fences,
>>> +			  u64 context, unsigned seqno,
>>> +			  bool signal_on_any)
>>>    {
>>> -	struct dma_fence_array *array;
>>> -
>>>    	WARN_ON(!num_fences || !fences);
>>> -	array = kzalloc(struct_size(array, callbacks, num_fences), GFP_KERNEL);
>>> -	if (!array)
>>> -		return NULL;
>>> -
>>>    	array->num_fences = num_fences;
>>>    	spin_lock_init(&array->lock);
>>> @@ -200,6 +201,41 @@ struct dma_fence_array *dma_fence_array_create(int num_fences,
>>>    	 */
>>>    	while (num_fences--)
>>>    		WARN_ON(dma_fence_is_container(fences[num_fences]));
>>> +}
>>> +EXPORT_SYMBOL(dma_fence_array_init);
>>> +
>>> +/**
>>> + * dma_fence_array_create - Create a custom fence array
>>> + * @num_fences:		[in]	number of fences to add in the array
>>> + * @fences:		[in]	array containing the fences
>>> + * @context:		[in]	fence context to use
>>> + * @seqno:		[in]	sequence number to use
>>> + * @signal_on_any:	[in]	signal on any fence in the array
>>> + *
>>> + * Allocate a dma_fence_array object and initialize the base fence with
>>> + * dma_fence_init().
>>> + * In case of error it returns NULL.
>>> + *
>>> + * The caller should allocate the fences array with num_fences size
>>> + * and fill it with the fences it wants to add to the object. Ownership of this
>>> + * array is taken and dma_fence_put() is used on each fence on release.
>>> + *
>>> + * If @signal_on_any is true the fence array signals if any fence in the array
>>> + * signals, otherwise it signals when all fences in the array signal.
>>> + */
>>> +struct dma_fence_array *dma_fence_array_create(int num_fences,
>>> +					       struct dma_fence **fences,
>>> +					       u64 context, unsigned seqno,
>>> +					       bool signal_on_any)
>>> +{
>>> +	struct dma_fence_array *array;
>>> +
>>> +	array = dma_fence_array_alloc(num_fences);
>>> +	if (!array)
>>> +		return NULL;
>>> +
>>> +	dma_fence_array_init(array, num_fences, fences,
>>> +			     context, seqno, signal_on_any);
>>>    	return array;
>>>    }
>>> diff --git a/include/linux/dma-fence-array.h b/include/linux/dma-fence-array.h
>>> index 29c5650c1038..079b3dec0a16 100644
>>> --- a/include/linux/dma-fence-array.h
>>> +++ b/include/linux/dma-fence-array.h
>>> @@ -79,6 +79,12 @@ to_dma_fence_array(struct dma_fence *fence)
>>>    	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_alloc(int num_fences);
>>> +void dma_fence_array_init(struct dma_fence_array *array,
>>> +			  int num_fences, struct dma_fence **fences,
>>> +			  u64 context, unsigned seqno,
>>> +			  bool signal_on_any);
>>> +
>>>    struct dma_fence_array *dma_fence_array_create(int num_fences,
>>>    					       struct dma_fence **fences,
>>>    					       u64 context, unsigned seqno,