drm/sched: Fix race in drm_sched_entity_select_rq()

[ Upstream commit d25e3a6 ]

In a past bug fix it was forgotten that entity access must be protected
by the entity lock. That's a data race and potentially UB.

Move the spin_unlock() to the appropriate position.

Cc: stable@vger.kernel.org # v5.13+
Fixes: ac4eb83 ("drm/sched: select new rq even if there is only one v3")
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@igalia.com>
Signed-off-by: Philipp Stanner <phasta@kernel.org>
Link: https://patch.msgid.link/20251022063402.87318-2-phasta@kernel.org
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Author: Philipp Stanner

drivers/gpu/drm/scheduler/sched_entity.c

@@ -558,10 +558,11 @@ void drm_sched_entity_select_rq(struct drm_sched_entity *entity)
 		drm_sched_rq_remove_entity(entity->rq, entity);
 		entity->rq = rq;
 	}
-	spin_unlock(&entity->lock);
 
 	if (entity->num_sched_list == 1)
 		entity->sched_list = NULL;
+
+	spin_unlock(&entity->lock);
 }
 
 /**