[PATCH v2] drm/amdgpu: only keep most recent fence for each context

[Yadav, Arvind]

On 4/23/2025 5:43 PM, Christian König wrote:
> On 4/23/25 12:52, Khatri, Sunil wrote:
>
>> [AMD Official Use Only - AMD Internal Distribution Only]
>>
>> You need to split this in a dma_buf patch and amd userq patch 
>> separately.
>
> Yeah agree, and the dma_buf patch should re-use and re-structure the 
> existing code and not just add a new function.
>
sure, I will not add new function and try to re-use existing.

Thankyou,
~arvind

>
> Regards,
> Christian.
>>
>> Regards
>> Sunil Khatri
>>
>> -----Original Message-----
>> From: Yadav, Arvind <Arvind.Yadav at amd.com>
>> Sent: Wednesday, April 23, 2025 4:18 PM
>> To: Koenig, Christian <Christian.Koenig at amd.com>; Deucher, Alexander 
>> <Alexander.Deucher at amd.com>; Khatri, Sunil <Sunil.Khatri at amd.com>; 
>> Paneer Selvam, Arunpravin <Arunpravin.PaneerSelvam at amd.com>
>> Cc: amd-gfx at lists.freedesktop.org; Yadav, Arvind 
>> <Arvind.Yadav at amd.com>; Koenig, Christian <Christian.Koenig at amd.com>; 
>> Yadav, Arvind <Arvind.Yadav at amd.com>
>> Subject: [PATCH v2] drm/amdgpu: only keep most recent fence for each 
>> context
>>
>> Mesa passes shared bo, fence syncobj to userq_ioctl.
>> There can be duplicates here or some fences that are old.
>> This patch is remove duplicates fence and only keep the most recent 
>> fence for each context.
>>
>> v2: Export this code from dma-fence-unwrap.c(by Christian).
>>
>> Cc: Alex Deucher <alexander.deucher at amd.com>
>> Cc: Christian König <christian.koenig at amd.com>
>> Cc: Sunil Khatri <sunil.khatri at amd.com>
>> Cc: Arunpravin Paneer Selvam <Arunpravin.PaneerSelvam at amd.com>
>> Signed-off-by: Arvind Yadav <arvind.yadav at amd.com>
>> ---
>>   drivers/dma-buf/dma-fence-unwrap.c            | 29 +++++++++++++++++++
>>   .../gpu/drm/amd/amdgpu/amdgpu_userq_fence.c   |  2 ++
>>   include/linux/dma-fence-unwrap.h              |  3 ++
>>   3 files changed, 34 insertions(+)
>>
>> diff --git a/drivers/dma-buf/dma-fence-unwrap.c 
>> b/drivers/dma-buf/dma-fence-unwrap.c
>> index 2a059ac0ed27..18874eedf091 100644
>> --- a/drivers/dma-buf/dma-fence-unwrap.c
>> +++ b/drivers/dma-buf/dma-fence-unwrap.c
>> @@ -179,3 +179,32 @@ struct dma_fence 
>> *__dma_fence_unwrap_merge(unsigned int num_fences,
>>          return tmp;
>>   }
>>   EXPORT_SYMBOL_GPL(__dma_fence_unwrap_merge);
>> +
>> +/**
>> + * dma_fence_shrink_array - return the shrink fences from fence
>> +containers
>> + * @fences: array of fence
>> + * @num_fences: number of fence in fence array @fences
>> + *
>> + * only keep most recent fence for each context. It will remove
>> +duplicate
>> + * and old fence of same context.
>> + */
>> +unsigned short dma_fence_shrink_array(struct dma_fence **fences,
>> +                                     unsigned short num_fences)
>> +{
>> +       unsigned short count = 0;
>> +
>> +       if (num_fences <= 1)
>> +               return num_fences;
>> +
>> +       sort(fences, num_fences, sizeof(*fences), fence_cmp, NULL);
>> +
>> +       for (int i = 1; i < num_fences; i++) {
>> +               if (fences[i]->context == fences[count]->context)
>> +                       dma_fence_put(fences[i]);
>> +               else
>> +                       fences[++count] = fences[i];
>> +       }
>> +
>> +       return ++count;
>> +}
>> +EXPORT_SYMBOL_GPL(dma_fence_shrink_array);
>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_userq_fence.c 
>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_userq_fence.c
>> index 3288c2ff692e..cc74bb0ed06f 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_userq_fence.c
>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_userq_fence.c
>> @@ -851,6 +851,8 @@ int amdgpu_userq_wait_ioctl(struct drm_device 
>> *dev, void *data,
>>                          fences[num_fences++] = fence;
>>                  }
>>
>> +               num_fences = dma_fence_shrink_array(fences, num_fences);
>> +
>>                  waitq = idr_find(&userq_mgr->userq_idr, 
>> wait_info->waitq_id);
>>                  if (!waitq)
>>                          goto free_fences;
>> diff --git a/include/linux/dma-fence-unwrap.h 
>> b/include/linux/dma-fence-unwrap.h
>> index 66b1e56fbb81..94801feeee4b 100644
>> --- a/include/linux/dma-fence-unwrap.h
>> +++ b/include/linux/dma-fence-unwrap.h
>> @@ -72,4 +72,7 @@ struct dma_fence *__dma_fence_unwrap_merge(unsigned 
>> int num_fences,
>>                  __dma_fence_unwrap_merge(ARRAY_SIZE(__f), __f, 
>> __c);    \
>>          })
>>
>> +
>> +unsigned short dma_fence_shrink_array(struct dma_fence **fences,
>> +                                     unsigned short num_fences);
>>   #endif
>> -- 
>> 2.34.1
>>