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drm/sched: Remove racy hack from drm_sched_fini()

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drm_sched_fini() contained a hack to work around a race in amdgpu.
According to AMD, the hack should not be necessary anymore. In case
there should have been undetected users,

commit 975ca62a01 ("drm/sched: Add warning for removing hack in drm_sched_fini()")

had added a warning one release cycle ago.

Thus, it can be derived that the hack can be savely removed by now.

Remove the hack.

Acked-by: Danilo Krummrich <dakr@kernel.org>
Signed-off-by: Philipp Stanner <phasta@kernel.org>
Link: https://patch.msgid.link/20260108083019.63532-2-phasta@kernel.org
This commit is contained in:
Philipp Stanner 2026-01-08 09:30:20 +01:00
parent bbe814bcb9
commit 4827d6d83f
1 changed files with 1 additions and 37 deletions
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38
drivers/gpu/drm/scheduler/sched_main.c
View File

@ -1418,48 +1418,12 @@ static void drm_sched_cancel_remaining_jobs(struct drm_gpu_scheduler *sched)
*/
void drm_sched_fini(struct drm_gpu_scheduler *sched)
{
struct drm_sched_entity *s_entity;
int i;
drm_sched_wqueue_stop(sched);
for (i = DRM_SCHED_PRIORITY_KERNEL; i < sched->num_rqs; i++) {
struct drm_sched_rq *rq = sched->sched_rq[i];
spin_lock(&rq->lock);
list_for_each_entry(s_entity, &rq->entities, list) {
/*
* Prevents reinsertion and marks job_queue as idle,
* it will be removed from the rq in drm_sched_entity_fini()
* eventually
*
* FIXME:
* This lacks the proper spin_lock(&s_entity->lock) and
* is, therefore, a race condition. Most notably, it
* can race with drm_sched_entity_push_job(). The lock
* cannot be taken here, however, because this would
* lead to lock inversion -> deadlock.
*
* The best solution probably is to enforce the life
* time rule of all entities having to be torn down
* before their scheduler. Then, however, locking could
* be dropped alltogether from this function.
*
* For now, this remains a potential race in all
* drivers that keep entities alive for longer than
* the scheduler.
*
* The READ_ONCE() is there to make the lockless read
* (warning about the lockless write below) slightly
* less broken...
*/
if (!READ_ONCE(s_entity->stopped))
dev_warn(sched->dev, "Tearing down scheduler with active entities!\n");
s_entity->stopped = true;
}
spin_unlock(&rq->lock);
for (i = DRM_SCHED_PRIORITY_KERNEL; i < sched->num_rqs; i++)
kfree(sched->sched_rq[i]);
}
/* Wakeup everyone stuck in drm_sched_entity_flush for this scheduler */
wake_up_all(&sched->job_scheduled);