[PATCH] dma-buf: fix reservation_object_wait_timeout_rcu to wait correctly v2

[Christian König]

Ping, what do you guys think of that?

Am 25.07.2017 um 15:35 schrieb Christian König:
> From: Christian König <christian.koenig at amd.com>
>
> With hardware resets in mind it is possible that all shared fences are
> signaled, but the exlusive isn't. Fix waiting for everything in this situation.
>
> v2: make sure we always wait for the exclusive fence
>
> Signed-off-by: Christian König <christian.koenig at amd.com>
> ---
>   drivers/dma-buf/reservation.c | 33 +++++++++++++++------------------
>   1 file changed, 15 insertions(+), 18 deletions(-)
>
> diff --git a/drivers/dma-buf/reservation.c b/drivers/dma-buf/reservation.c
> index 393817e..9d4316d 100644
> --- a/drivers/dma-buf/reservation.c
> +++ b/drivers/dma-buf/reservation.c
> @@ -373,12 +373,25 @@ long reservation_object_wait_timeout_rcu(struct reservation_object *obj,
>   	long ret = timeout ? timeout : 1;
>   
>   retry:
> -	fence = NULL;
>   	shared_count = 0;
>   	seq = read_seqcount_begin(&obj->seq);
>   	rcu_read_lock();
>   
> -	if (wait_all) {
> +	fence = rcu_dereference(obj->fence_excl);
> +	if (fence && !test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags)) {
> +		if (!dma_fence_get_rcu(fence))
> +			goto unlock_retry;
> +
> +		if (dma_fence_is_signaled(fence)) {
> +			dma_fence_put(fence);
> +			fence = NULL;
> +		}
> +
> +	} else {
> +		fence = NULL;
> +	}
> +
> +	if (!fence && wait_all) {
>   		struct reservation_object_list *fobj =
>   						rcu_dereference(obj->fence);
>   
> @@ -405,22 +418,6 @@ long reservation_object_wait_timeout_rcu(struct reservation_object *obj,
>   		}
>   	}
>   
> -	if (!shared_count) {
> -		struct dma_fence *fence_excl = rcu_dereference(obj->fence_excl);
> -
> -		if (fence_excl &&
> -		    !test_bit(DMA_FENCE_FLAG_SIGNALED_BIT,
> -			      &fence_excl->flags)) {
> -			if (!dma_fence_get_rcu(fence_excl))
> -				goto unlock_retry;
> -
> -			if (dma_fence_is_signaled(fence_excl))
> -				dma_fence_put(fence_excl);
> -			else
> -				fence = fence_excl;
> -		}
> -	}
> -
>   	rcu_read_unlock();
>   	if (fence) {
>   		if (read_seqcount_retry(&obj->seq, seq)) {