[PATCH v3] drm/scheduler: Fix hang when sched_entity released
Andrey Grodzovsky
andrey.grodzovsky at amd.com
Fri Feb 26 15:36:04 UTC 2021
On 2021-02-26 3:04 a.m., Christian König wrote:
>
>
> Am 25.02.21 um 22:37 schrieb Andrey Grodzovsky:
>> Problem: If scheduler is already stopped by the time sched_entity
>> is released and entity's job_queue not empty I encountred
>> a hang in drm_sched_entity_flush. This is because
>> drm_sched_entity_is_idle
>> never becomes false.
>>
>> Fix: In drm_sched_fini detach all sched_entities from the
>> scheduler's run queues. This will satisfy drm_sched_entity_is_idle.
>> Also wakeup all those processes stuck in sched_entity flushing
>> as the scheduler main thread which wakes them up is stopped by now.
>>
>> v2:
>> Reverse order of drm_sched_rq_remove_entity and marking
>> s_entity as stopped to prevent reinserion back to rq due
>> to race.
>>
>> v3:
>> Drop drm_sched_rq_remove_entity, only modify entity->stopped
>> and check for it in drm_sched_entity_is_idle
>>
>> Signed-off-by: Andrey Grodzovsky <andrey.grodzovsky at amd.com>
>> ---
>> drivers/gpu/drm/scheduler/sched_entity.c | 3 ++-
>> drivers/gpu/drm/scheduler/sched_main.c | 23 +++++++++++++++++++++++
>> 2 files changed, 25 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/gpu/drm/scheduler/sched_entity.c
>> b/drivers/gpu/drm/scheduler/sched_entity.c
>> index 92d965b629c6..68b10813129a 100644
>> --- a/drivers/gpu/drm/scheduler/sched_entity.c
>> +++ b/drivers/gpu/drm/scheduler/sched_entity.c
>> @@ -116,7 +116,8 @@ static bool drm_sched_entity_is_idle(struct
>> drm_sched_entity *entity)
>> rmb(); /* for list_empty to work without lock */
>> if (list_empty(&entity->list) ||
>> - spsc_queue_count(&entity->job_queue) == 0)
>> + spsc_queue_count(&entity->job_queue) == 0 ||
>> + entity->stopped)
>> return true;
>> return false;
>> diff --git a/drivers/gpu/drm/scheduler/sched_main.c
>> b/drivers/gpu/drm/scheduler/sched_main.c
>> index 908b0b56032d..b50fab472734 100644
>> --- a/drivers/gpu/drm/scheduler/sched_main.c
>> +++ b/drivers/gpu/drm/scheduler/sched_main.c
>> @@ -897,9 +897,32 @@ EXPORT_SYMBOL(drm_sched_init);
>> */
>> void drm_sched_fini(struct drm_gpu_scheduler *sched)
>> {
>> + int i;
>> + struct drm_sched_entity *s_entity;
>
> Please declare i last and have an empty line between declaration and
> code.
>
> With that nit pick fixed the patch is Reviewed-by: Christian König
> <christian.koenig at amd.com>. Going to push it to drm-misc-next.
>
> Christian.
Done. Since you are pushing attaching the patch here.
Andrey
>
>> if (sched->thread)
>> kthread_stop(sched->thread);
>> + for (i = DRM_SCHED_PRIORITY_COUNT - 1; i >=
>> DRM_SCHED_PRIORITY_MIN; i--) {
>> + struct drm_sched_rq *rq = &sched->sched_rq[i];
>> +
>> + if (!rq)
>> + continue;
>> +
>> + spin_lock(&rq->lock);
>> + list_for_each_entry(s_entity, &rq->entities, list)
>> + /*
>> + * Prevents reinsertion and marks job_queue as idle,
>> + * it will removed from rq in drm_sched_entity_fini
>> + * eventually
>> + */
>> + s_entity->stopped = true;
>> + spin_unlock(&rq->lock);
>> +
>> + }
>> +
>> + /* Wakeup everyone stuck in drm_sched_entity_flush for this
>> scheduler */
>> + wake_up_all(&sched->job_scheduled);
>> +
>> /* Confirm no work left behind accessing device structures */
>> cancel_delayed_work_sync(&sched->work_tdr);
>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: 0001-drm-scheduler-Fix-hang-when-sched_entity-released.patch
Type: text/x-patch
Size: 3018 bytes
Desc: not available
URL: <https://lists.freedesktop.org/archives/dri-devel/attachments/20210226/4f1d531b/attachment.bin>
More information about the dri-devel
mailing list