Re: [PATCH 5/6] RFC: dma-buf: Add an extra fence to dma_resv_get_singleton_unlocked

[Christian König <christian.koenig@xxxxxxx>]

Am 10.06.21 um 23:09 schrieb Jason Ekstrand:
> For dma-buf sync_file import, we want to get all the fences on a
> dma_resv plus one more.  We could wrap the fence we get back in an array
> fence or we could make dma_resv_get_singleton_unlocked take "one more"
> to make this case easier.
>
> Signed-off-by: Jason Ekstrand <jason@xxxxxxxxxxxxxx>
> Reviewed-by: Daniel Vetter <daniel.vetter@xxxxxxxx>

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

> Cc: Christian König <christian.koenig@xxxxxxx>
> Cc: Maarten Lankhorst <maarten.lankhorst@xxxxxxxxxxxxxxx>
> ---
>   drivers/dma-buf/dma-buf.c  |  2 +-
>   drivers/dma-buf/dma-resv.c | 23 +++++++++++++++++++++--
>   include/linux/dma-resv.h   |  3 ++-
>   3 files changed, 24 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c
> index 41b14b53cdda3..831828d71b646 100644
> --- a/drivers/dma-buf/dma-buf.c
> +++ b/drivers/dma-buf/dma-buf.c
> @@ -389,7 +389,7 @@ static long dma_buf_export_sync_file(struct dma_buf *dmabuf,
>   		return fd;
>   
>   	if (arg.flags & DMA_BUF_SYNC_WRITE) {
> -		fence = dma_resv_get_singleton(dmabuf->resv);
> +		fence = dma_resv_get_singleton(dmabuf->resv, NULL);
>   		if (IS_ERR(fence)) {
>   			ret = PTR_ERR(fence);
>   			goto err_put_fd;
> diff --git a/drivers/dma-buf/dma-resv.c b/drivers/dma-buf/dma-resv.c
> index 1b26aa7e5d81c..7c48c23239b4b 100644
> --- a/drivers/dma-buf/dma-resv.c
> +++ b/drivers/dma-buf/dma-resv.c
> @@ -504,6 +504,7 @@ EXPORT_SYMBOL_GPL(dma_resv_get_fences);
>   /**
>    * dma_resv_get_singleton - get a single fence for the dma_resv object
>    * @obj: the reservation object
> + * @extra: extra fence to add to the resulting array
>    *
>    * Get a single fence representing all unsignaled fences in the dma_resv object
>    * plus the given extra fence. If we got only one fence return a new
> @@ -512,7 +513,8 @@ EXPORT_SYMBOL_GPL(dma_resv_get_fences);
>    * RETURNS
>    * The singleton dma_fence on success or an ERR_PTR on failure
>    */
> -struct dma_fence *dma_resv_get_singleton(struct dma_resv *obj)
> +struct dma_fence *dma_resv_get_singleton(struct dma_resv *obj,
> +					 struct dma_fence *extra)
>   {
>   	struct dma_fence *result, **resv_fences, *fence, *chain, **fences;
>   	struct dma_fence_array *array;
> @@ -523,7 +525,7 @@ struct dma_fence *dma_resv_get_singleton(struct dma_resv *obj)
>   	if (err)
>   		return ERR_PTR(err);
>   
> -	if (num_resv_fences == 0)
> +	if (num_resv_fences == 0 && !extra)
>   		return NULL;
>   
>   	num_fences = 0;
> @@ -539,6 +541,16 @@ struct dma_fence *dma_resv_get_singleton(struct dma_resv *obj)
>   		}
>   	}
>   
> +	if (extra) {
> +		dma_fence_deep_dive_for_each(fence, chain, j, extra) {
> +			if (dma_fence_is_signaled(fence))
> +				continue;
> +
> +			result = fence;
> +			++num_fences;
> +		}
> +	}
> +
>   	if (num_fences <= 1) {
>   		result = dma_fence_get(result);
>   		goto put_resv_fences;
> @@ -559,6 +571,13 @@ struct dma_fence *dma_resv_get_singleton(struct dma_resv *obj)
>   		}
>   	}
>   
> +	if (extra) {
> +		dma_fence_deep_dive_for_each(fence, chain, j, extra) {
> +			if (dma_fence_is_signaled(fence))
> +				fences[num_fences++] = dma_fence_get(fence);
> +		}
> +	}
> +
>   	if (num_fences <= 1) {
>   		result = num_fences ? fences[0] : NULL;
>   		kfree(fences);
> diff --git a/include/linux/dma-resv.h b/include/linux/dma-resv.h
> index d60982975a786..f970e03fc1a08 100644
> --- a/include/linux/dma-resv.h
> +++ b/include/linux/dma-resv.h
> @@ -275,7 +275,8 @@ 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_copy_fences(struct dma_resv *dst, struct dma_resv *src);
> -struct dma_fence *dma_resv_get_singleton(struct dma_resv *obj);
> +struct dma_fence *dma_resv_get_singleton(struct dma_resv *obj,
> +					 struct dma_fence *extra);
>   long dma_resv_wait_timeout(struct dma_resv *obj, bool wait_all, bool intr,
>   			   unsigned long timeout);
>   bool dma_resv_test_signaled(struct dma_resv *obj, bool test_all);