Re: [PATCH 11/24] drm/amdgpu: use dma_resv_for_each_fence for CS workaround

["Christian König" <ckoenig.leichtzumerken@gmail.com>]

Am 22.12.21 um 22:37 schrieb Daniel Vetter:
> On Tue, Dec 07, 2021 at 01:33:58PM +0100, Christian König wrote:
>> Get the write fence using dma_resv_for_each_fence instead of accessing
>> it manually.
>>
>> Signed-off-by: Christian König <christian.koenig@amd.com>
>> ---
>>   drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c | 9 ++++++---
>>   1 file changed, 6 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
>> index 53e407ea4c89..7facd614e50a 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
>> @@ -1268,6 +1268,8 @@ static int amdgpu_cs_submit(struct amdgpu_cs_parser *p,
>>   	amdgpu_bo_list_for_each_entry(e, p->bo_list) {
>>   		struct dma_resv *resv = e->tv.bo->base.resv;
>>   		struct dma_fence_chain *chain = e->chain;
>> +		struct dma_resv_iter cursor;
>> +		struct dma_fence *fence;
>>   
>>   		if (!chain)
>>   			continue;
>> @@ -1277,9 +1279,10 @@ static int amdgpu_cs_submit(struct amdgpu_cs_parser *p,
>>   		 * submission in a dma_fence_chain and add it as exclusive
>>   		 * fence.
>>   		 */
>> -		dma_fence_chain_init(chain, dma_resv_excl_fence(resv),
>> -				     dma_fence_get(p->fence), 1);
>> -
>> +		dma_resv_for_each_fence(&cursor, resv, false, fence) {
>> +			break;
>> +		}
>> +		dma_fence_chain_init(chain, fence, dma_fence_get(p->fence), 1);
> Uh this needs a TODO. I'm assuming you'll fix this up later on when
> there's more than write fence, but in case of bisect or whatever this is a
> bit too clever. Like you just replace one "dig around in dma-resv
> implementation details" with one that's not even a documented interface
> :-)

Ah, yes. There is a rather big TODO just above this, but I should 
probably make that even more stronger.

>
> With an adequately loud comment added interim:
>
> Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>

Thanks,
Christian.

>
>>   		rcu_assign_pointer(resv->fence_excl, &chain->base);
>>   		e->chain = NULL;
>>   	}
>> -- 
>> 2.25.1
>>