lkml.org 
[lkml]   [2021]   [Jul]   [6]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH AUTOSEL 5.10 027/137] drm/scheduler: Fix hang when sched_entity released
    Date
    From: Andrey Grodzovsky <andrey.grodzovsky@amd.com>

    [ Upstream commit c61cdbdbffc169dc7f1e6fe94dfffaf574fe672a ]

    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@amd.com>
    Reviewed-by: Christian König <christian.koenig@amd.com>
    Link: https://patchwork.freedesktop.org/patch/msgid/20210512142648.666476-14-andrey.grodzovsky@amd.com
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    drivers/gpu/drm/scheduler/sched_entity.c | 3 ++-
    drivers/gpu/drm/scheduler/sched_main.c | 24 ++++++++++++++++++++++++
    2 files changed, 26 insertions(+), 1 deletion(-)

    diff --git a/drivers/gpu/drm/scheduler/sched_entity.c b/drivers/gpu/drm/scheduler/sched_entity.c
    index 146380118962..2006cc057f99 100644
    --- a/drivers/gpu/drm/scheduler/sched_entity.c
    +++ b/drivers/gpu/drm/scheduler/sched_entity.c
    @@ -113,7 +113,8 @@ 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 7111e0f527b0..b6c2757c3d83 100644
    --- a/drivers/gpu/drm/scheduler/sched_main.c
    +++ b/drivers/gpu/drm/scheduler/sched_main.c
    @@ -887,9 +887,33 @@ EXPORT_SYMBOL(drm_sched_init);
    */
    void drm_sched_fini(struct drm_gpu_scheduler *sched)
    {
    + struct drm_sched_entity *s_entity;
    + int i;
    +
    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);

    --
    2.30.2
    \
     
     \ /
      Last update: 2021-07-06 14:39    [W:4.208 / U:0.008 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site