[PATCH] dma-buf: keep the signaling time of merged fences

[Christian König]

Alex, Luben or somebody else at least a bit familiar with that, can I 
get a quick rb or acked-by?

This is an important bug fix for Android CTS.

Thanks,
Christian.

Am 21.06.23 um 09:32 schrieb Christian König:
> Some Android CTS is testing for that.
>
> Signed-off-by: Christian König <christian.koenig at amd.com>
> CC: stable at vger.kernel.org
> ---
>   drivers/dma-buf/dma-fence-unwrap.c | 11 +++++++++--
>   drivers/dma-buf/dma-fence.c        |  5 +++--
>   drivers/gpu/drm/drm_syncobj.c      |  2 +-
>   include/linux/dma-fence.h          |  2 +-
>   4 files changed, 14 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/dma-buf/dma-fence-unwrap.c b/drivers/dma-buf/dma-fence-unwrap.c
> index 7002bca792ff..06eb91306c01 100644
> --- a/drivers/dma-buf/dma-fence-unwrap.c
> +++ b/drivers/dma-buf/dma-fence-unwrap.c
> @@ -66,18 +66,25 @@ struct dma_fence *__dma_fence_unwrap_merge(unsigned int num_fences,
>   {
>   	struct dma_fence_array *result;
>   	struct dma_fence *tmp, **array;
> +	ktime_t timestamp;
>   	unsigned int i;
>   	size_t count;
>   
>   	count = 0;
> +	timestamp = ns_to_ktime(0);
>   	for (i = 0; i < num_fences; ++i) {
> -		dma_fence_unwrap_for_each(tmp, &iter[i], fences[i])
> +		dma_fence_unwrap_for_each(tmp, &iter[i], fences[i]) {
>   			if (!dma_fence_is_signaled(tmp))
>   				++count;
> +			else if (test_bit(DMA_FENCE_FLAG_TIMESTAMP_BIT,
> +					  &tmp->flags) &&
> +				 ktime_after(tmp->timestamp, timestamp))
> +				timestamp = tmp->timestamp;
> +		}
>   	}
>   
>   	if (count == 0)
> -		return dma_fence_get_stub();
> +		return dma_fence_allocate_private_stub(timestamp);
>   
>   	array = kmalloc_array(count, sizeof(*array), GFP_KERNEL);
>   	if (!array)
> diff --git a/drivers/dma-buf/dma-fence.c b/drivers/dma-buf/dma-fence.c
> index f177c56269bb..ad076f208760 100644
> --- a/drivers/dma-buf/dma-fence.c
> +++ b/drivers/dma-buf/dma-fence.c
> @@ -150,10 +150,11 @@ EXPORT_SYMBOL(dma_fence_get_stub);
>   
>   /**
>    * dma_fence_allocate_private_stub - return a private, signaled fence
> + * @timestamp: timestamp when the fence was signaled
>    *
>    * Return a newly allocated and signaled stub fence.
>    */
> -struct dma_fence *dma_fence_allocate_private_stub(void)
> +struct dma_fence *dma_fence_allocate_private_stub(ktime_t timestamp)
>   {
>   	struct dma_fence *fence;
>   
> @@ -169,7 +170,7 @@ struct dma_fence *dma_fence_allocate_private_stub(void)
>   	set_bit(DMA_FENCE_FLAG_ENABLE_SIGNAL_BIT,
>   		&fence->flags);
>   
> -	dma_fence_signal(fence);
> +	dma_fence_signal_timestamp(fence, timestamp);
>   
>   	return fence;
>   }
> diff --git a/drivers/gpu/drm/drm_syncobj.c b/drivers/gpu/drm/drm_syncobj.c
> index 0c2be8360525..04589a35eb09 100644
> --- a/drivers/gpu/drm/drm_syncobj.c
> +++ b/drivers/gpu/drm/drm_syncobj.c
> @@ -353,7 +353,7 @@ EXPORT_SYMBOL(drm_syncobj_replace_fence);
>    */
>   static int drm_syncobj_assign_null_handle(struct drm_syncobj *syncobj)
>   {
> -	struct dma_fence *fence = dma_fence_allocate_private_stub();
> +	struct dma_fence *fence = dma_fence_allocate_private_stub(ktime_get());
>   
>   	if (IS_ERR(fence))
>   		return PTR_ERR(fence);
> diff --git a/include/linux/dma-fence.h b/include/linux/dma-fence.h
> index d54b595a0fe0..0d678e9a7b24 100644
> --- a/include/linux/dma-fence.h
> +++ b/include/linux/dma-fence.h
> @@ -606,7 +606,7 @@ static inline signed long dma_fence_wait(struct dma_fence *fence, bool intr)
>   void dma_fence_set_deadline(struct dma_fence *fence, ktime_t deadline);
>   
>   struct dma_fence *dma_fence_get_stub(void);
> -struct dma_fence *dma_fence_allocate_private_stub(void);
> +struct dma_fence *dma_fence_allocate_private_stub(ktime_t timestamp);
>   u64 dma_fence_context_alloc(unsigned num);
>   
>   extern const struct dma_fence_ops dma_fence_array_ops;