drm_sched_entity_is_idle() contains a badly documented memory barrier and an invalid lockless access to entity->stopped. Moreover, it also accesses entity->list which is at all other places protected by entity->lock.
This function is in no way performance critical, so it is safer, more readable and more maintainable to take the spinlock. Add locking to drm_sched_entity_is_idle(). Signed-off-by: Philipp Stanner <[email protected]> --- drivers/gpu/drm/scheduler/sched_entity.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) diff --git a/drivers/gpu/drm/scheduler/sched_entity.c b/drivers/gpu/drm/scheduler/sched_entity.c index c51101ec70c1..2d941b2b2861 100644 --- a/drivers/gpu/drm/scheduler/sched_entity.c +++ b/drivers/gpu/drm/scheduler/sched_entity.c @@ -179,14 +179,18 @@ EXPORT_SYMBOL(drm_sched_entity_modify_sched); static bool drm_sched_entity_is_idle(struct drm_sched_entity *entity) { - rmb(); /* for list_empty to work without lock */ + bool idle = false; + + spin_lock(&entity->lock); if (list_empty(&entity->list) || spsc_queue_count(&entity->job_queue) == 0 || entity->stopped) - return true; + idle = true; - return false; + spin_unlock(&entity->lock); + + return idle; } /** base-commit: c9a2c8ddcd65e96e7f095a87c0cc0b3211f740ea -- 2.55.0
