6.12-stable review patch. If anyone has any objections, please let me know.
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From: Tvrtko Ursulin tvrtko.ursulin@igalia.com
[ Upstream commit d42a254633c773921884a19e8a1a0f53a31150c3 ]
In FIFO mode (which is the default), both drm_sched_entity_push_job() and drm_sched_rq_update_fifo(), where the latter calls the former, are currently taking and releasing the same entity->rq_lock.
We can avoid that design inelegance, and also have a miniscule efficiency improvement on the submit from idle path, by introducing a new drm_sched_rq_update_fifo_locked() helper and pulling up the lock taking to its callers.
v2: * Remove drm_sched_rq_update_fifo() altogether. (Christian)
v3: * Improved commit message. (Philipp)
Signed-off-by: Tvrtko Ursulin tvrtko.ursulin@igalia.com 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: Philipp Stanner pstanner@redhat.com Reviewed-by: Christian König christian.koenig@amd.com Signed-off-by: Philipp Stanner pstanner@redhat.com Link: https://patchwork.freedesktop.org/patch/msgid/20241016122013.7857-2-tursulin... Stable-dep-of: d25e3a610bae ("drm/sched: Fix race in drm_sched_entity_select_rq()") Signed-off-by: Sasha Levin sashal@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/gpu/drm/scheduler/sched_entity.c | 13 +++++++++---- drivers/gpu/drm/scheduler/sched_main.c | 6 +++--- include/drm/gpu_scheduler.h | 2 +- 3 files changed, 13 insertions(+), 8 deletions(-)
--- a/drivers/gpu/drm/scheduler/sched_entity.c +++ b/drivers/gpu/drm/scheduler/sched_entity.c @@ -506,8 +506,12 @@ struct drm_sched_job *drm_sched_entity_p struct drm_sched_job *next;
next = to_drm_sched_job(spsc_queue_peek(&entity->job_queue)); - if (next) - drm_sched_rq_update_fifo(entity, next->submit_ts); + if (next) { + spin_lock(&entity->rq_lock); + drm_sched_rq_update_fifo_locked(entity, + next->submit_ts); + spin_unlock(&entity->rq_lock); + } }
/* Jobs and entities might have different lifecycles. Since we're @@ -607,10 +611,11 @@ void drm_sched_entity_push_job(struct dr sched = rq->sched;
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_rq_update_fifo_locked(entity, submit_ts); + + spin_unlock(&entity->rq_lock);
drm_sched_wakeup(sched); } --- a/drivers/gpu/drm/scheduler/sched_main.c +++ b/drivers/gpu/drm/scheduler/sched_main.c @@ -169,14 +169,15 @@ static inline void drm_sched_rq_remove_f } }
-void drm_sched_rq_update_fifo(struct drm_sched_entity *entity, ktime_t ts) +void drm_sched_rq_update_fifo_locked(struct drm_sched_entity *entity, ktime_t ts) { /* * Both locks need to be grabbed, one to protect from entity->rq change * for entity from within concurrent drm_sched_entity_select_rq and the * other to update the rb tree structure. */ - spin_lock(&entity->rq_lock); + lockdep_assert_held(&entity->rq_lock); + spin_lock(&entity->rq->lock);
drm_sched_rq_remove_fifo_locked(entity); @@ -187,7 +188,6 @@ void drm_sched_rq_update_fifo(struct drm drm_sched_entity_compare_before);
spin_unlock(&entity->rq->lock); - spin_unlock(&entity->rq_lock); }
/** --- a/include/drm/gpu_scheduler.h +++ b/include/drm/gpu_scheduler.h @@ -593,7 +593,7 @@ void drm_sched_rq_add_entity(struct drm_ void drm_sched_rq_remove_entity(struct drm_sched_rq *rq, struct drm_sched_entity *entity);
-void drm_sched_rq_update_fifo(struct drm_sched_entity *entity, ktime_t ts); +void drm_sched_rq_update_fifo_locked(struct drm_sched_entity *entity, ktime_t ts);
int drm_sched_entity_init(struct drm_sched_entity *entity, enum drm_sched_priority priority,