On Fri, 2024-09-06 at 19:06 +0100, Tvrtko Ursulin wrote:

From: Tvrtko Ursulin tvrtko.ursulin@igalia.com

Since drm_sched_entity_modify_sched() can modify the entities run queue lets make sure to only derefernce the pointer once so both adding and waking up are guaranteed to be consistent.

Signed-off-by: Tvrtko Ursulin tvrtko.ursulin@igalia.com Fixes: b37aced31eb0 ("drm/scheduler: implement a function to modify sched list") Cc: Christian König christian.koenig@amd.com Cc: Alex Deucher alexander.deucher@amd.com Cc: Luben Tuikov ltuikov89@gmail.com Cc: Matthew Brost matthew.brost@intel.com Cc: David Airlie airlied@gmail.com Cc: Daniel Vetter daniel@ffwll.ch Cc: dri-devel@lists.freedesktop.org Cc: stable@vger.kernel.org # v5.7+

---

drivers/gpu/drm/scheduler/sched_entity.c | 8 ++++++--  1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/scheduler/sched_entity.c b/drivers/gpu/drm/scheduler/sched_entity.c index ae8be30472cd..62b07ef7630a 100644 --- a/drivers/gpu/drm/scheduler/sched_entity.c +++ b/drivers/gpu/drm/scheduler/sched_entity.c @@ -599,6 +599,8 @@ void drm_sched_entity_push_job(struct drm_sched_job *sched_job)     /* first job wakes up scheduler */   if (first) {

• struct drm_sched_rq *rq;
  

/* Add the entity to the run queue */   spin_lock(&entity->rq_lock);   if (entity->stopped) { @@ -608,13 +610,15 @@ void drm_sched_entity_push_job(struct drm_sched_job *sched_job)   return;   }

• drm_sched_rq_add_entity(entity->rq, entity);
  

• rq = entity->rq;
  

• drm_sched_rq_add_entity(rq, entity);
  

spin_unlock(&entity->rq_lock);     if (drm_sched_policy == DRM_SCHED_POLICY_FIFO)   drm_sched_rq_update_fifo(entity, submit_ts);

• drm_sched_wakeup(entity->rq->sched, entity);
  

• drm_sched_wakeup(rq->sched, entity);
  

OK, I think that makes sense. But I'd mention that the more readable solution of moving the spin_unlock() down here cannot be done because drm_sched_rq_update_fifo() needs that same lock.

P.

}  }  EXPORT_SYMBOL(drm_sched_entity_push_job);