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

[zhoucm1]

On 2017年07月31日 23:39, Deucher, Alexander wrote:
>> -----Original Message-----
>> From: Christian König [mailto:deathsimple at vodafone.de]
>> Sent: Monday, July 31, 2017 10:13 AM
>> To: linux-media at vger.kernel.org; dri-devel at lists.freedesktop.org; linaro-
>> mm-sig at lists.linaro.org; Zhou, David(ChunMing); Deucher, Alexander
>> Subject: Re: [PATCH] dma-buf: fix reservation_object_wait_timeout_rcu to
>> wait correctly v2
>>
>> Ping, what do you guys think of that?
> Seems reasonable to me.
> Reviewed-by: Alex Deucher <alexander.deucher at amd.com>
Reviewed-by: Chunming Zhou <david1.zhou at amd.com> as well.

>
>> 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)) {