[PATCH 1/5] drm/amdgpu: Fix possible refcount leak for release of external_hw_fence

[Christian König]

Am 22.06.22 um 17:01 schrieb Andrey Grodzovsky:
>
> On 2022-06-22 05:00, Christian König wrote:
>> Am 21.06.22 um 21:34 schrieb Andrey Grodzovsky:
>>> On 2022-06-21 03:19, Christian König wrote:
>>>
>>>> Am 21.06.22 um 00:02 schrieb Andrey Grodzovsky:
>>>>> Problem:
>>>>> In amdgpu_job_submit_direct - The refcount should drop by 2
>>>>> but it drops only by 1.
>>>>>
>>>>> amdgpu_ib_sched->emit -> refcount 1 from first fence init
>>>>> dma_fence_get -> refcount 2
>>>>> dme_fence_put -> refcount 1
>>>>>
>>>>> Fix:
>>>>> Add put for external_hw_fence in amdgpu_job_free/free_cb
>>>>
>>>> Well what is the external_hw_fence good for in this construct?
>>>
>>>
>>> As far as I understand for direct submissions you don't want to pass 
>>> a job
>>> pointer to ib_schedule and so u can't use the embedded fence for 
>>> this case.
>>
>> Can you please look a bit deeper into this, we now have a couple of 
>> fields in the job structure which have no obvious use.
>>
>> I think we could pass a job structure to ib_schedule even for direct 
>> submit now.
>
>
> Are you sure  ? I see a lot of activities in amdgpu_ib_schedule depend 
> on presence of  vm and fence_ctx which are set if the job pointer 
> argument != NULL, might this have a negative impact on direct submit ?

Not 100% sure, but we did tons of workarounds because we didn't had a 
job pointer for direct submit.

But this was before we embedded the IBs at the end of the job.

It's quite likely that this should be possible now, it's just that 
somebody needs to double check.

Christian.

>
> Andrey
>
>
>>
>> Regards,
>> Christian.
>>
>>>
>>> Andrey
>>>
>>>
>>>>
>>>>>
>>>>> Signed-off-by: Andrey Grodzovsky <andrey.grodzovsky at amd.com>
>>>>> ---
>>>>>   drivers/gpu/drm/amd/amdgpu/amdgpu_job.c | 8 ++++++--
>>>>>   1 file changed, 6 insertions(+), 2 deletions(-)
>>>>>
>>>>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_job.c 
>>>>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_job.c
>>>>> index 10aa073600d4..58568fdde2d0 100644
>>>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_job.c
>>>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_job.c
>>>>> @@ -152,8 +152,10 @@ static void amdgpu_job_free_cb(struct 
>>>>> drm_sched_job *s_job)
>>>>>       /* only put the hw fence if has embedded fence */
>>>>>       if (job->hw_fence.ops != NULL)
>>>>>           dma_fence_put(&job->hw_fence);
>>>>> -    else
>>>>> +    else {
>>>>
>>>> When one side of the if uses {} the other side should use {} as 
>>>> well, e.g. use } else { here.
>>>>
>>>> Christian.
>>>>
>>>>> + dma_fence_put(job->external_hw_fence);
>>>>>           kfree(job);
>>>>> +    }
>>>>>   }
>>>>>     void amdgpu_job_free(struct amdgpu_job *job)
>>>>> @@ -165,8 +167,10 @@ void amdgpu_job_free(struct amdgpu_job *job)
>>>>>       /* only put the hw fence if has embedded fence */
>>>>>       if (job->hw_fence.ops != NULL)
>>>>>           dma_fence_put(&job->hw_fence);
>>>>> -    else
>>>>> +    else {
>>>>> +        dma_fence_put(job->external_hw_fence);
>>>>>           kfree(job);
>>>>> +    }
>>>>>   }
>>>>>     int amdgpu_job_submit(struct amdgpu_job *job, struct 
>>>>> drm_sched_entity *entity,
>>>>
>>