[PATCH 3/6] drm/amdgpu: screen freeze and userq driver crash

[Paneer Selvam, Arunpravin]

Hi Christian,

On 9/5/2024 4:50 PM, Christian König wrote:
> Am 30.08.24 um 20:43 schrieb Arunpravin Paneer Selvam:
>> Screen freeze and userq fence driver crash while playing Xonotic
>>
>> Signed-off-by: Arunpravin Paneer Selvam 
>> <Arunpravin.PaneerSelvam at amd.com>
>> ---
>>   drivers/gpu/drm/amd/amdgpu/amdgpu_userq_fence.c | 12 +++++++-----
>>   1 file changed, 7 insertions(+), 5 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_userq_fence.c 
>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_userq_fence.c
>> index d2e1d0d0f29f..8a3b5374cc1a 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_userq_fence.c
>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_userq_fence.c
>> @@ -187,6 +187,7 @@ int amdgpu_userq_fence_create(struct 
>> amdgpu_usermode_queue *userq,
>>       struct amdgpu_userq_fence_driver *fence_drv;
>>       struct amdgpu_userq_fence *userq_fence;
>>       struct dma_fence *fence;
>> +    unsigned long flags;
>>         fence_drv = userq->fence_drv;
>>       if (!fence_drv)
>> @@ -230,14 +231,15 @@ int amdgpu_userq_fence_create(struct 
>> amdgpu_usermode_queue *userq,
>>           }
>>       }
>>   -    spin_lock(&fence_drv->fence_list_lock);
>>       /* Check if hardware has already processed the job */
>> -    if (!dma_fence_is_signaled(fence))
>> +    if (!dma_fence_is_signaled(fence)) {
>> +        spin_lock_irqsave(&fence_drv->fence_list_lock, flags);
>
> As far as I can see that still won't work correctly since you can't 
> guarantee that the fence doesn't signal in between testing and 
> grabbing the lock.
Can I move the spin lock little up before the if .. else check.

Thanks,
Arun.
>
> Christian.
>
>
>
>> list_add_tail(&userq_fence->link, &fence_drv->fences);
>> -    else
>> -        dma_fence_put(fence);
>>   -    spin_unlock(&fence_drv->fence_list_lock);
>> + spin_unlock_irqrestore(&fence_drv->fence_list_lock, flags);
>> +    } else {
>> +        dma_fence_put(fence);
>> +    }
>>         *f = fence;
>