Re: [PATCH 3/3] dma-buf/fence: add signal_on_any to the fence array

From: Daniel Vetter
Date: Mon May 23 2016 - 09:50:54 EST


On Mon, May 23, 2016 at 01:25:22PM +0200, Christian König wrote:
> From: Christian König <christian.koenig@xxxxxxx>
>
> 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.

What do you need this for? Sounds neat, but I can't come up with a use
case. And that use case imo should be both in the commit message and
kerneldoc.
-Daniel

>
> Signed-off-by: Christian König <christian.koenig@xxxxxxx>
> ---
> drivers/dma-buf/fence-array.c | 23 ++++++++++++++++-------
> include/linux/fence-array.h | 3 ++-
> 2 files changed, 18 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/dma-buf/fence-array.c b/drivers/dma-buf/fence-array.c
> index bbcf79f..726e840 100644
> --- a/drivers/dma-buf/fence-array.c
> +++ b/drivers/dma-buf/fence-array.c
> @@ -41,6 +41,7 @@ static void fence_array_cb_func(struct fence *f, struct fence_cb *cb)
>
> if (atomic_dec_and_test(&array->num_pending))
> fence_signal(&array->base);
> + fence_put(&array->base);
> }
>
> static bool fence_array_enable_signaling(struct fence *fence)
> @@ -51,10 +52,13 @@ static bool fence_array_enable_signaling(struct fence *fence)
>
> for (i = 0; i < array->num_fences; ++i) {
> cb[i].array = array;
> + fence_get(&array->base);
> if (!fence_add_callback(array->fences[i], &cb[i].cb,
> - fence_array_cb_func))
> + fence_array_cb_func)) {
> + fence_put(&array->base);
> if (atomic_dec_and_test(&array->num_pending))
> return false;
> + }
> }
>
> return true;
> @@ -90,10 +94,11 @@ const struct fence_ops fence_array_ops = {
>
> /**
> * 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
> + * @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 fence_array object and initialize the base fence with fence_init().
> * In case of error it returns NULL.
> @@ -101,9 +106,13 @@ const struct fence_ops fence_array_ops = {
> * The caller should allocte 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 take and 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 fence_array *fence_array_create(int num_fences, struct fence **fences,
> - u64 context, unsigned seqno)
> + u64 context, unsigned seqno,
> + bool signal_on_any)
> {
> struct fence_array *array;
> size_t size = sizeof(*array);
> @@ -119,7 +128,7 @@ struct fence_array *fence_array_create(int num_fences, struct fence **fences,
> context, seqno);
>
> array->num_fences = num_fences;
> - atomic_set(&array->num_pending, num_fences);
> + atomic_set(&array->num_pending, signal_on_any ? 1 : num_fences);
> array->fences = fences;
>
> return array;
> diff --git a/include/linux/fence-array.h b/include/linux/fence-array.h
> index 593ab98..86baaa4 100644
> --- a/include/linux/fence-array.h
> +++ b/include/linux/fence-array.h
> @@ -67,6 +67,7 @@ static inline struct fence_array *to_fence_array(struct fence *fence)
> }
>
> struct fence_array *fence_array_create(int num_fences, struct fence **fences,
> - u64 context, unsigned seqno);
> + u64 context, unsigned seqno,
> + bool signal_on_any);
>
> #endif /* __LINUX_FENCE_ARRAY_H */
> --
> 2.5.0
>

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