[PATCH] drm/amdgpu: Force signal hw_fences that are embedded in non-sched jobs

[Luben Tuikov]

Hi,

Thanks for your patch!

On 2023-03-07 02:07, Christian König wrote:
> Am 07.03.23 um 08:02 schrieb YuBiao Wang:
>> [Why]
>> For engines not supporting soft reset, i.e. VCN, there will be a failed
>> ib test before mode 1 reset during asic reset. The fences in this case
>> are never signaled and next time when we try to free the sa_bo, kernel
>> will hang.
>>
>> [How]
>> During pre_asic_reset, driver will clear job fences and afterwards the
>> fences' refcount will be reduced to 1. For drm_sched_jobs it will be
>> released in job_free_cb, and for non-sched jobs like ib_test, it's meant
>> to be released in sa_bo_free but only when the fences are signaled. So

So, you're missing a signal for the non-scheduler job fences?

>> we have to force signal the non_sched bad job's fence during
>> pre_asic_reset or the clear is not complete.

Do you want to add a function which does just this (signals 
non-scheduler job fences) in amdgpu_device_pre_asic_reset(),
and resubmit your patch? (There will be code redundancy, but may
make the point clearer.)

Are we missing to signal non-scheduler job fences on reset altogether?
-- 
Regards,
Luben

> 
> Well NAK for now. It looks once more like one of those not very well 
> thought through changes.
> 
> Luben can you please take a look at this and double check it> 
> Thanks,
> Christian.
> 
>>
>> Signed-off-by: YuBiao Wang <YuBiao.Wang at amd.com>
>> ---
>>   drivers/gpu/drm/amd/amdgpu/amdgpu_fence.c | 4 ++++
>>   1 file changed, 4 insertions(+)
>>
>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_fence.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_fence.c
>> index faff4a3f96e6..2e549bd50990 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_fence.c
>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_fence.c
>> @@ -673,6 +673,7 @@ void amdgpu_fence_driver_clear_job_fences(struct amdgpu_ring *ring)
>>   {
>>   	int i;
>>   	struct dma_fence *old, **ptr;
>> +	struct amdgpu_job *job;
>>   
>>   	for (i = 0; i <= ring->fence_drv.num_fences_mask; i++) {
>>   		ptr = &ring->fence_drv.fences[i];
>> @@ -680,6 +681,9 @@ void amdgpu_fence_driver_clear_job_fences(struct amdgpu_ring *ring)
>>   		if (old && old->ops == &amdgpu_job_fence_ops) {
>>   			RCU_INIT_POINTER(*ptr, NULL);
>>   			dma_fence_put(old);
>> +			job = container_of(old, struct amdgpu_job, hw_fence);
>> +			if (!job->base.s_fence && !dma_fence_is_signaled(old))
>> +				dma_fence_signal(old);
>>   		}
>>   	}
>>   }
>