Re: [PATCH 1/2] drm/sched: Set error to s_fence if HW job submission failed.

["Grodzovsky, Andrey" <Andrey.Grodzovsky@amd.com>]

On 10/25/19 4:44 AM, Christian König wrote:
> Am 24.10.19 um 21:57 schrieb Andrey Grodzovsky:
>> Problem:
>> When run_job fails and HW fence returned is NULL we still signal
>> the s_fence to avoid hangs but the user has no way of knowing if
>> the actual HW job was ran and finished.
>>
>> Fix:
>> Allow .run_job implementations to return ERR_PTR in the fence pointer
>> returned and then set this error for s_fence->finished fence so whoever
>> wait on this fence can inspect the signaled fence for an error.
>>
>> Signed-off-by: Andrey Grodzovsky <andrey.grodzovsky@amd.com>
>> ---
>>   drivers/gpu/drm/scheduler/sched_main.c | 19 ++++++++++++++++---
>>   1 file changed, 16 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/scheduler/sched_main.c 
>> b/drivers/gpu/drm/scheduler/sched_main.c
>> index 9a0ee74..f39b97e 100644
>> --- a/drivers/gpu/drm/scheduler/sched_main.c
>> +++ b/drivers/gpu/drm/scheduler/sched_main.c
>> @@ -479,6 +479,7 @@ void drm_sched_resubmit_jobs(struct 
>> drm_gpu_scheduler *sched)
>>       struct drm_sched_job *s_job, *tmp;
>>       uint64_t guilty_context;
>>       bool found_guilty = false;
>> +    struct dma_fence *fence;
>>         list_for_each_entry_safe(s_job, tmp, 
>> &sched->ring_mirror_list, node) {
>>           struct drm_sched_fence *s_fence = s_job->s_fence;
>> @@ -492,7 +493,16 @@ void drm_sched_resubmit_jobs(struct 
>> drm_gpu_scheduler *sched)
>>               dma_fence_set_error(&s_fence->finished, -ECANCELED);
>>             dma_fence_put(s_job->s_fence->parent);
>> -        s_job->s_fence->parent = sched->ops->run_job(s_job);
>> +        fence = sched->ops->run_job(s_job);
>> +
>> +        if (IS_ERR_OR_NULL(fence)) {
>> +            s_job->s_fence->parent = NULL;
>> +            dma_fence_set_error(&s_fence->finished, PTR_ERR(fence));
>> +        } else {
>> +            s_job->s_fence->parent = fence;
>> +        }
>> +
>> +
>
> Maybe time for a drm_sched_run_job() function which does that 
> handling? And why don't we need to install the callback here?


What code do you want to put in drm_sched_run_job ?

We reinstall the callback later in drm_sched_start, 
drm_sched_resubmit_jobs is conditional on whether the guilty fence did 
signal by this time or not and so the split of the logic into 
drm_sched_start and drm_sched_resubmit_jobs.

Andrey


>
> Apart from that looks good to me,
> Christian.
>
>>       }
>>   }
>>   EXPORT_SYMBOL(drm_sched_resubmit_jobs);
>> @@ -720,7 +730,7 @@ static int drm_sched_main(void *param)
>>           fence = sched->ops->run_job(sched_job);
>>           drm_sched_fence_scheduled(s_fence);
>>   -        if (fence) {
>> +        if (!IS_ERR_OR_NULL(fence)) {
>>               s_fence->parent = dma_fence_get(fence);
>>               r = dma_fence_add_callback(fence, &sched_job->cb,
>>                              drm_sched_process_job);
>> @@ -730,8 +740,11 @@ static int drm_sched_main(void *param)
>>                   DRM_ERROR("fence add callback failed (%d)\n",
>>                         r);
>>               dma_fence_put(fence);
>> -        } else
>> +        } else {
>> +
>> +            dma_fence_set_error(&s_fence->finished, PTR_ERR(fence));
>>               drm_sched_process_job(NULL, &sched_job->cb);
>> +        }
>>             wake_up(&sched->job_scheduled);
>>       }
>
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