[PATCH] drm/scheduler: only kill entity if last user is killed

[Christian König]

Note which task is using the entity and only kill it if the last user of
the entity is killed. This should prevent problems when entities are leaked to
child processes.

Signed-off-by: Christian König <christian.koenig at amd.com>
---
 drivers/gpu/drm/scheduler/gpu_scheduler.c | 6 +++++-
 include/drm/gpu_scheduler.h               | 1 +
 2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/scheduler/gpu_scheduler.c b/drivers/gpu/drm/scheduler/gpu_scheduler.c
index 3f2fc5e8242a..f563e4fbb4b6 100644
--- a/drivers/gpu/drm/scheduler/gpu_scheduler.c
+++ b/drivers/gpu/drm/scheduler/gpu_scheduler.c
@@ -275,6 +275,7 @@ static void drm_sched_entity_kill_jobs_cb(struct dma_fence *f,
 long drm_sched_entity_flush(struct drm_sched_entity *entity, long timeout)
 {
 	struct drm_gpu_scheduler *sched;
+	struct task_struct *last_user;
 	long ret = timeout;
 
 	sched = entity->rq->sched;
@@ -295,7 +296,9 @@ long drm_sched_entity_flush(struct drm_sched_entity *entity, long timeout)
 
 
 	/* For killed process disable any more IBs enqueue right now */
-	if ((current->flags & PF_EXITING) && (current->exit_code == SIGKILL))
+	last_user = cmpxchg(&entity->last_user, current->group_leader, NULL);
+	if ((!last_user || last_user == current->group_leader) &&
+	    (current->flags & PF_EXITING) && (current->exit_code == SIGKILL))
 		drm_sched_entity_set_rq(entity, NULL);
 
 	return ret;
@@ -541,6 +544,7 @@ void drm_sched_entity_push_job(struct drm_sched_job *sched_job,
 
 	trace_drm_sched_job(sched_job, entity);
 
+	WRITE_ONCE(entity->last_user, current->group_leader);
 	first = spsc_queue_push(&entity->job_queue, &sched_job->queue_node);
 
 	/* first job wakes up scheduler */
diff --git a/include/drm/gpu_scheduler.h b/include/drm/gpu_scheduler.h
index 091b9afcd184..64016446a103 100644
--- a/include/drm/gpu_scheduler.h
+++ b/include/drm/gpu_scheduler.h
@@ -85,6 +85,7 @@ struct drm_sched_entity {
 	struct dma_fence_cb		cb;
 	atomic_t			*guilty;
 	struct dma_fence                *last_scheduled;
+	struct task_struct		*last_user;
 };
 
 /**
-- 
2.14.1