linux-kernel - Re: [PATCH 3/3] dma-buf/fence: add signal_on

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Message-ID: <20160523135049.GA27098@phenom.ffwll.local>
Date:	Mon, 23 May 2016 15:50:50 +0200
From:	Daniel Vetter <daniel@...ll.ch>
To:	Christian König <deathsimple@...afone.de>
Cc:	dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
	daniel@...ll.ch, gustavo@...ovan.org, chris@...is-wilson.co.uk
Subject: Re: [PATCH 3/3] dma-buf/fence: add signal_on_any to the fence array

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