Re: [PATCH 03/24] dma-buf: drop excl_fence parameter from dma_resv_get_fences

[Daniel Vetter <daniel@ffwll.ch>]

On Tue, Dec 07, 2021 at 01:33:50PM +0100, Christian König wrote:
> Returning the exclusive fence separately is no longer used.
> 
> Instead add a write parameter to indicate the use case.
> 
> Signed-off-by: Christian König <christian.koenig@amd.com>
> ---
>  drivers/dma-buf/dma-resv.c                   | 48 ++++++++------------
>  drivers/dma-buf/st-dma-resv.c                | 26 ++---------
>  drivers/gpu/drm/amd/amdgpu/amdgpu_display.c  |  6 ++-
>  drivers/gpu/drm/amd/amdgpu/amdgpu_ids.c      |  2 +-
>  drivers/gpu/drm/etnaviv/etnaviv_gem_submit.c |  3 +-
>  include/linux/dma-resv.h                     |  4 +-
>  6 files changed, 31 insertions(+), 58 deletions(-)
> 
> diff --git a/drivers/dma-buf/dma-resv.c b/drivers/dma-buf/dma-resv.c
> index a12a3a39f280..480c305554a1 100644
> --- a/drivers/dma-buf/dma-resv.c
> +++ b/drivers/dma-buf/dma-resv.c
> @@ -611,57 +611,45 @@ EXPORT_SYMBOL(dma_resv_copy_fences);
>   * dma_resv_get_fences - Get an object's shared and exclusive
>   * fences without update side lock held
>   * @obj: the reservation object
> - * @fence_excl: the returned exclusive fence (or NULL)
> - * @shared_count: the number of shared fences returned
> - * @shared: the array of shared fence ptrs returned (array is krealloc'd to
> - * the required size, and must be freed by caller)
> - *
> - * Retrieve all fences from the reservation object. If the pointer for the
> - * exclusive fence is not specified the fence is put into the array of the
> - * shared fences as well. Returns either zero or -ENOMEM.
> + * @write: true if we should return all fences

I'm assuming that this will be properly documented later on in the series
...

> + * @num_fences: the number of fences returned
> + * @fences: the array of fence ptrs returned (array is krealloc'd to the
> + * required size, and must be freed by caller)
> + *
> + * Retrieve all fences from the reservation object.
> + * Returns either zero or -ENOMEM.
>   */
> -int dma_resv_get_fences(struct dma_resv *obj, struct dma_fence **fence_excl,
> -			unsigned int *shared_count, struct dma_fence ***shared)
> +int dma_resv_get_fences(struct dma_resv *obj, bool write,
> +			unsigned int *num_fences, struct dma_fence ***fences)
>  {
>  	struct dma_resv_iter cursor;
>  	struct dma_fence *fence;
>  
> -	*shared_count = 0;
> -	*shared = NULL;
> -
> -	if (fence_excl)
> -		*fence_excl = NULL;
> +	*num_fences = 0;
> +	*fences = NULL;
>  
> -	dma_resv_iter_begin(&cursor, obj, true);
> +	dma_resv_iter_begin(&cursor, obj, write);
>  	dma_resv_for_each_fence_unlocked(&cursor, fence) {
>  
>  		if (dma_resv_iter_is_restarted(&cursor)) {
>  			unsigned int count;
>  
> -			while (*shared_count)
> -				dma_fence_put((*shared)[--(*shared_count)]);
> +			while (*num_fences)
> +				dma_fence_put((*fences)[--(*num_fences)]);
>  
> -			if (fence_excl)
> -				dma_fence_put(*fence_excl);
> -
> -			count = cursor.shared_count;
> -			count += fence_excl ? 0 : 1;
> +			count = cursor.shared_count + 1;
>  
>  			/* Eventually re-allocate the array */
> -			*shared = krealloc_array(*shared, count,
> +			*fences = krealloc_array(*fences, count,
>  						 sizeof(void *),
>  						 GFP_KERNEL);
> -			if (count && !*shared) {
> +			if (count && !*fences) {
>  				dma_resv_iter_end(&cursor);
>  				return -ENOMEM;
>  			}
>  		}
>  
> -		dma_fence_get(fence);
> -		if (dma_resv_iter_is_exclusive(&cursor) && fence_excl)
> -			*fence_excl = fence;
> -		else
> -			(*shared)[(*shared_count)++] = fence;
> +		(*fences)[(*num_fences)++] = dma_fence_get(fence);
>  	}
>  	dma_resv_iter_end(&cursor);
>  
> diff --git a/drivers/dma-buf/st-dma-resv.c b/drivers/dma-buf/st-dma-resv.c
> index bc32b3eedcb6..cbe999c6e7a6 100644
> --- a/drivers/dma-buf/st-dma-resv.c
> +++ b/drivers/dma-buf/st-dma-resv.c
> @@ -275,7 +275,7 @@ static int test_shared_for_each_unlocked(void *arg)
>  
>  static int test_get_fences(void *arg, bool shared)
>  {
> -	struct dma_fence *f, *excl = NULL, **fences = NULL;
> +	struct dma_fence *f, **fences = NULL;
>  	struct dma_resv resv;
>  	int r, i;
>  
> @@ -304,35 +304,19 @@ static int test_get_fences(void *arg, bool shared)
>  	}
>  	dma_resv_unlock(&resv);
>  
> -	r = dma_resv_get_fences(&resv, &excl, &i, &fences);
> +	r = dma_resv_get_fences(&resv, shared, &i, &fences);
>  	if (r) {
>  		pr_err("get_fences failed\n");
>  		goto err_free;
>  	}
>  
> -	if (shared) {
> -		if (excl != NULL) {
> -			pr_err("get_fences returned unexpected excl fence\n");
> -			goto err_free;
> -		}
> -		if (i != 1 || fences[0] != f) {
> -			pr_err("get_fences returned unexpected shared fence\n");
> -			goto err_free;
> -		}
> -	} else {
> -		if (excl != f) {
> -			pr_err("get_fences returned unexpected excl fence\n");
> -			goto err_free;
> -		}
> -		if (i != 0) {
> -			pr_err("get_fences returned unexpected shared fence\n");
> -			goto err_free;
> -		}
> +	if (i != 1 || fences[0] != f) {
> +		pr_err("get_fences returned unexpected fence\n");
> +		goto err_free;
>  	}
>  
>  	dma_fence_signal(f);
>  err_free:
> -	dma_fence_put(excl);
>  	while (i--)
>  		dma_fence_put(fences[i]);
>  	kfree(fences);
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_display.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_display.c
> index 68108f151dad..d17e1c911689 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_display.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_display.c
> @@ -200,8 +200,10 @@ int amdgpu_display_crtc_page_flip_target(struct drm_crtc *crtc,
>  		goto unpin;
>  	}
>  
> -	r = dma_resv_get_fences(new_abo->tbo.base.resv, NULL,
> -				&work->shared_count, &work->shared);
> +	/* TODO: Unify this with other drivers */
> +	r = dma_resv_get_fences(new_abo->tbo.base.resv, true,
> +				&work->shared_count,
> +				&work->shared);
>  	if (unlikely(r != 0)) {
>  		DRM_ERROR("failed to get fences for buffer\n");
>  		goto unpin;
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ids.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ids.c
> index b7fb72bff2c1..be48487e2ca7 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ids.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ids.c
> @@ -112,7 +112,7 @@ void amdgpu_pasid_free_delayed(struct dma_resv *resv,
>  	unsigned count;
>  	int r;
>  
> -	r = dma_resv_get_fences(resv, NULL, &count, &fences);
> +	r = dma_resv_get_fences(resv, true, &count, &fences);
>  	if (r)
>  		goto fallback;
>  
> diff --git a/drivers/gpu/drm/etnaviv/etnaviv_gem_submit.c b/drivers/gpu/drm/etnaviv/etnaviv_gem_submit.c
> index b5e8ce86dbe7..64c90ff348f2 100644
> --- a/drivers/gpu/drm/etnaviv/etnaviv_gem_submit.c
> +++ b/drivers/gpu/drm/etnaviv/etnaviv_gem_submit.c
> @@ -189,8 +189,7 @@ static int submit_fence_sync(struct etnaviv_gem_submit *submit)
>  			continue;
>  
>  		if (bo->flags & ETNA_SUBMIT_BO_WRITE) {
> -			ret = dma_resv_get_fences(robj, NULL,
> -						  &bo->nr_shared,
> +			ret = dma_resv_get_fences(robj, true, &bo->nr_shared,
>  						  &bo->shared);
>  			if (ret)
>  				return ret;
> diff --git a/include/linux/dma-resv.h b/include/linux/dma-resv.h
> index 3baf2a4a9a0d..fa2002939b19 100644
> --- a/include/linux/dma-resv.h
> +++ b/include/linux/dma-resv.h
> @@ -436,8 +436,8 @@ void dma_resv_add_shared_fence(struct dma_resv *obj, struct dma_fence *fence);
>  void dma_resv_replace_fences(struct dma_resv *obj, uint64_t context,
>  			     struct dma_fence *fence);
>  void dma_resv_add_excl_fence(struct dma_resv *obj, struct dma_fence *fence);
> -int dma_resv_get_fences(struct dma_resv *obj, struct dma_fence **pfence_excl,
> -			unsigned *pshared_count, struct dma_fence ***pshared);
> +int dma_resv_get_fences(struct dma_resv *obj, bool write,
> +			unsigned int *num_fences, struct dma_fence ***fences);
>  int dma_resv_copy_fences(struct dma_resv *dst, struct dma_resv *src);
>  long dma_resv_wait_timeout(struct dma_resv *obj, bool wait_all, bool intr,
>  			   unsigned long timeout);
> -- 
> 2.25.1
> 


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

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