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

[Christian König]

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 at 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?

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);
>   	}