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drm/sched: Lock drm_sched_entity_is_idle()

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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().

Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@igalia.com>
Signed-off-by: Philipp Stanner <phasta@kernel.org>
Link: https://patch.msgid.link/20260813094539.2407911-2-phasta@kernel.org
This commit is contained in:
Philipp Stanner 2026-08-13 11:45:40 +02:00
parent 5d2584e2ff
commit 0e118b936d
1 changed files with 7 additions and 3 deletions
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10
drivers/gpu/drm/scheduler/sched_entity.c
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@ -179,14 +179,18 @@ EXPORT_SYMBOL(drm_sched_entity_modify_sched);
static bool drm_sched_entity_is_idle(struct drm_sched_entity *entity) 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) || if (list_empty(&entity->list) ||
spsc_queue_count(&entity->job_queue) == 0 || spsc_queue_count(&entity->job_queue) == 0 ||
entity->stopped) entity->stopped)
return true; idle = true;
return false; spin_unlock(&entity->lock);
return idle;
} }
/** /**