[PATCH 1/2] drm/scheduler: Avoid using wait_event_killable for dying process.

[Andrey Grodzovsky]

Dying process might be blocked from receiving any more signals
so avoid using it.

Also retire enity->fini_status and just check the SW queue,
if it's not empty do the fallback cleanup.

Also handle entity->last_scheduled == NULL use case which
happens when HW ring is already hangged whem a  new entity
tried to enqeue jobs.

Signed-off-by: Andrey Grodzovsky <andrey.grodzovsky at amd.com>
---
 drivers/gpu/drm/scheduler/gpu_scheduler.c | 47 ++++++++++++++++++++++---------
 include/drm/gpu_scheduler.h               |  1 -
 2 files changed, 34 insertions(+), 14 deletions(-)

diff --git a/drivers/gpu/drm/scheduler/gpu_scheduler.c b/drivers/gpu/drm/scheduler/gpu_scheduler.c
index 44d4807..4d038f9 100644
--- a/drivers/gpu/drm/scheduler/gpu_scheduler.c
+++ b/drivers/gpu/drm/scheduler/gpu_scheduler.c
@@ -135,7 +135,6 @@ int drm_sched_entity_init(struct drm_gpu_scheduler *sched,
 	entity->rq = rq;
 	entity->sched = sched;
 	entity->guilty = guilty;
-	entity->fini_status = 0;
 	entity->last_scheduled = NULL;
 
 	spin_lock_init(&entity->rq_lock);
@@ -173,7 +172,8 @@ static bool drm_sched_entity_is_initialized(struct drm_gpu_scheduler *sched,
 static bool drm_sched_entity_is_idle(struct drm_sched_entity *entity)
 {
 	rmb();
-	if (spsc_queue_peek(&entity->job_queue) == NULL)
+
+	if (entity->rq == NULL || spsc_queue_peek(&entity->job_queue) == NULL)
 		return true;
 
 	return false;
@@ -227,12 +227,16 @@ void drm_sched_entity_do_release(struct drm_gpu_scheduler *sched,
 	 * The client will not queue more IBs during this fini, consume existing
 	 * queued IBs or discard them on SIGKILL
 	*/
-	if ((current->flags & PF_SIGNALED) && current->exit_code == SIGKILL)
-		entity->fini_status = -ERESTARTSYS;
+	if ((current->flags & PF_EXITING))
+		wait_event_timeout(sched->job_scheduled,
+				drm_sched_entity_is_idle(entity), msecs_to_jiffies(1000));
 	else
-		entity->fini_status = wait_event_killable(sched->job_scheduled,
-					drm_sched_entity_is_idle(entity));
-	drm_sched_entity_set_rq(entity, NULL);
+		wait_event_killable(sched->job_scheduled, drm_sched_entity_is_idle(entity));
+
+
+	/* For killed process disable any more IBs enqueue right now */
+	if ((current->flags & PF_EXITING) && (current->exit_code == SIGKILL))
+		drm_sched_entity_set_rq(entity, NULL);
 }
 EXPORT_SYMBOL(drm_sched_entity_do_release);
 
@@ -247,7 +251,13 @@ EXPORT_SYMBOL(drm_sched_entity_do_release);
 void drm_sched_entity_cleanup(struct drm_gpu_scheduler *sched,
 			   struct drm_sched_entity *entity)
 {
-	if (entity->fini_status) {
+
+	drm_sched_entity_set_rq(entity, NULL);
+
+	/* Consumption of existing IBs wasn't completed. Forcefully
+	 * remove them here.
+	 */
+	if (spsc_queue_peek(&entity->job_queue)) {
 		struct drm_sched_job *job;
 		int r;
 
@@ -267,12 +277,22 @@ void drm_sched_entity_cleanup(struct drm_gpu_scheduler *sched,
 			struct drm_sched_fence *s_fence = job->s_fence;
 			drm_sched_fence_scheduled(s_fence);
 			dma_fence_set_error(&s_fence->finished, -ESRCH);
-			r = dma_fence_add_callback(entity->last_scheduled, &job->finish_cb,
-							drm_sched_entity_kill_jobs_cb);
-			if (r == -ENOENT)
+
+			/*
+			 * When pipe is hanged by older entity, new entity might
+			 * not even have chance to submit it's first job to HW
+			 * and so entity->last_scheduled will remain NULL
+			 */
+			if (!entity->last_scheduled)
 				drm_sched_entity_kill_jobs_cb(NULL, &job->finish_cb);
-			else if (r)
-				DRM_ERROR("fence add callback failed (%d)\n", r);
+			else {
+				r = dma_fence_add_callback(entity->last_scheduled, &job->finish_cb,
+								drm_sched_entity_kill_jobs_cb);
+				if (r == -ENOENT)
+					drm_sched_entity_kill_jobs_cb(NULL, &job->finish_cb);
+				else if (r)
+					DRM_ERROR("fence add callback failed (%d)\n", r);
+			}
 		}
 	}
 
@@ -713,6 +733,7 @@ static int drm_sched_main(void *param)
 			continue;
 
 		sched_job = drm_sched_entity_pop_job(entity);
+
 		if (!sched_job)
 			continue;
 
diff --git a/include/drm/gpu_scheduler.h b/include/drm/gpu_scheduler.h
index dec6558..d220ac9 100644
--- a/include/drm/gpu_scheduler.h
+++ b/include/drm/gpu_scheduler.h
@@ -64,7 +64,6 @@ struct drm_sched_entity {
 	struct dma_fence		*dependency;
 	struct dma_fence_cb		cb;
 	atomic_t			*guilty; /* points to ctx's guilty */
-	int            fini_status;
 	struct dma_fence    *last_scheduled;
 };
 
-- 
2.7.4