Re: [PATCH v2 1/4] drm/sched: Fix entities with 0 rqs.

[Alex Deucher via amd-gfx <amd-gfx-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW@public.gmane.org>]

On Wed, Jan 30, 2019 at 5:43 AM Christian König
<ckoenig.leichtzumerken@gmail.com> wrote:
>
> Am 30.01.19 um 02:53 schrieb Bas Nieuwenhuizen:
> > Some blocks in amdgpu can have 0 rqs.
> >
> > Job creation already fails with -ENOENT when entity->rq is NULL,
> > so jobs cannot be pushed. Without a rq there is no scheduler to
> > pop jobs, and rq selection already does the right thing with a
> > list of length 0.
> >
> > So the operations we need to fix are:
> >    - Creation, do not set rq to rq_list[0] if the list can have length 0.
> >    - Do not flush any jobs when there is no rq.
> >    - On entity destruction handle the rq = NULL case.
> >    - on set_priority, do not try to change the rq if it is NULL.
> >
> > Signed-off-by: Bas Nieuwenhuizen <bas@basnieuwenhuizen.nl>
>
> One minor comment on patch #2, apart from that the series is
> Reviewed-by: Christian König <christian.koenig@amd.com>.
>
> I'm going to make the change on #2 and pick them up for inclusion in
> amd-staging-drm-next.

Hi Christian,

I haven't seen these land yet.  Just want to make sure they don't fall
through the cracks.

Alex

>
> Thanks for the help,
> Christian.
>
> > ---
> >   drivers/gpu/drm/scheduler/sched_entity.c | 39 ++++++++++++++++--------
> >   1 file changed, 26 insertions(+), 13 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/scheduler/sched_entity.c b/drivers/gpu/drm/scheduler/sched_entity.c
> > index 4463d3826ecb..8e31b6628d09 100644
> > --- a/drivers/gpu/drm/scheduler/sched_entity.c
> > +++ b/drivers/gpu/drm/scheduler/sched_entity.c
> > @@ -52,12 +52,12 @@ int drm_sched_entity_init(struct drm_sched_entity *entity,
> >   {
> >       int i;
> >
> > -     if (!(entity && rq_list && num_rq_list > 0 && rq_list[0]))
> > +     if (!(entity && rq_list && (num_rq_list == 0 || rq_list[0])))
> >               return -EINVAL;
> >
> >       memset(entity, 0, sizeof(struct drm_sched_entity));
> >       INIT_LIST_HEAD(&entity->list);
> > -     entity->rq = rq_list[0];
> > +     entity->rq = NULL;
> >       entity->guilty = guilty;
> >       entity->num_rq_list = num_rq_list;
> >       entity->rq_list = kcalloc(num_rq_list, sizeof(struct drm_sched_rq *),
> > @@ -67,6 +67,10 @@ int drm_sched_entity_init(struct drm_sched_entity *entity,
> >
> >       for (i = 0; i < num_rq_list; ++i)
> >               entity->rq_list[i] = rq_list[i];
> > +
> > +     if (num_rq_list)
> > +             entity->rq = rq_list[0];
> > +
> >       entity->last_scheduled = NULL;
> >
> >       spin_lock_init(&entity->rq_lock);
> > @@ -165,6 +169,9 @@ long drm_sched_entity_flush(struct drm_sched_entity *entity, long timeout)
> >       struct task_struct *last_user;
> >       long ret = timeout;
> >
> > +     if (!entity->rq)
> > +             return 0;
> > +
> >       sched = entity->rq->sched;
> >       /**
> >        * The client will not queue more IBs during this fini, consume existing
> > @@ -264,20 +271,24 @@ static void drm_sched_entity_kill_jobs(struct drm_sched_entity *entity)
> >    */
> >   void drm_sched_entity_fini(struct drm_sched_entity *entity)
> >   {
> > -     struct drm_gpu_scheduler *sched;
> > +     struct drm_gpu_scheduler *sched = NULL;
> >
> > -     sched = entity->rq->sched;
> > -     drm_sched_rq_remove_entity(entity->rq, entity);
> > +     if (entity->rq) {
> > +             sched = entity->rq->sched;
> > +             drm_sched_rq_remove_entity(entity->rq, entity);
> > +     }
> >
> >       /* Consumption of existing IBs wasn't completed. Forcefully
> >        * remove them here.
> >        */
> >       if (spsc_queue_peek(&entity->job_queue)) {
> > -             /* Park the kernel for a moment to make sure it isn't processing
> > -              * our enity.
> > -              */
> > -             kthread_park(sched->thread);
> > -             kthread_unpark(sched->thread);
> > +             if (sched) {
> > +                     /* Park the kernel for a moment to make sure it isn't processing
> > +                      * our enity.
> > +                      */
> > +                     kthread_park(sched->thread);
> > +                     kthread_unpark(sched->thread);
> > +             }
> >               if (entity->dependency) {
> >                       dma_fence_remove_callback(entity->dependency,
> >                                                 &entity->cb);
> > @@ -362,9 +373,11 @@ void drm_sched_entity_set_priority(struct drm_sched_entity *entity,
> >       for (i = 0; i < entity->num_rq_list; ++i)
> >               drm_sched_entity_set_rq_priority(&entity->rq_list[i], priority);
> >
> > -     drm_sched_rq_remove_entity(entity->rq, entity);
> > -     drm_sched_entity_set_rq_priority(&entity->rq, priority);
> > -     drm_sched_rq_add_entity(entity->rq, entity);
> > +     if (entity->rq) {
> > +             drm_sched_rq_remove_entity(entity->rq, entity);
> > +             drm_sched_entity_set_rq_priority(&entity->rq, priority);
> > +             drm_sched_rq_add_entity(entity->rq, entity);
> > +     }
> >
> >       spin_unlock(&entity->rq_lock);
> >   }
>
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