drm/sched: Always trace the dependencies we wait on, to fix a race.

commit 82abf33766712d8446ea137a3400165e31bd12c7 upstream.

The entity->dependency can go away completely once we've called
drm_sched_entity_add_dependency_cb() (if the cb is called before we
get around to tracing).  The tracepoint is more useful if we trace
every dependency instead of just ones that get callbacks installed,
anyway, so just do that.

Fixes any easy-to-produce OOPS when tracing the scheduler on V3D with
"perf record -a -e gpu_scheduler:.\* glxgears" and DEBUG_SLAB enabled.

Signed-off-by: Eric Anholt <eric@anholt.net>
Reviewed-by: Christian König <christian.koenig@amd.com>
Cc: stable@vger.kernel.org
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/gpu/drm/scheduler/sched_entity.c b/drivers/gpu/drm/scheduler/sched_entity.c
index 3e22a54a99c25b52c62ece421596695faf3d3489..2c02f5b03db8abed8c7102aa6ed79b87af777256 100644 (file)
--- a/drivers/gpu/drm/scheduler/sched_entity.c
+++ b/drivers/gpu/drm/scheduler/sched_entity.c
@@ -434,13 +434,10 @@ struct drm_sched_job *drm_sched_entity_pop_job(struct drm_sched_entity *entity)
 
        while ((entity->dependency =
                        sched->ops->dependency(sched_job, entity))) {
+               trace_drm_sched_job_wait_dep(sched_job, entity->dependency);
 
-               if (drm_sched_entity_add_dependency_cb(entity)) {
-
-                       trace_drm_sched_job_wait_dep(sched_job,
-                                                    entity->dependency);
+               if (drm_sched_entity_add_dependency_cb(entity))
                        return NULL;
-               }
        }
 
        /* skip jobs from entity that marked guilty */