[PATCH 2/2] drm/sched: serialize job_timeout and scheduler
Daniel Vetter
daniel at ffwll.ch
Tue Aug 31 14:03:32 UTC 2021
On Tue, Aug 31, 2021 at 09:53:36AM -0400, Andrey Grodzovsky wrote:
> It's says patch [2/2] but i can't find patch 1
>
> On 2021-08-31 6:35 a.m., Monk Liu wrote:
> > tested-by: jingwen chen <jingwen.chen at amd.com>
> > Signed-off-by: Monk Liu <Monk.Liu at amd.com>
> > Signed-off-by: jingwen chen <jingwen.chen at amd.com>
> > ---
> > drivers/gpu/drm/scheduler/sched_main.c | 24 ++++--------------------
> > 1 file changed, 4 insertions(+), 20 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/scheduler/sched_main.c b/drivers/gpu/drm/scheduler/sched_main.c
> > index ecf8140..894fdb24 100644
> > --- a/drivers/gpu/drm/scheduler/sched_main.c
> > +++ b/drivers/gpu/drm/scheduler/sched_main.c
> > @@ -319,19 +319,17 @@ static void drm_sched_job_timedout(struct work_struct *work)
> > sched = container_of(work, struct drm_gpu_scheduler, work_tdr.work);
> > /* Protects against concurrent deletion in drm_sched_get_cleanup_job */
> > + if (!__kthread_should_park(sched->thread))
> > + kthread_park(sched->thread);
> > +
>
>
> As mentioned before, without serializing against other TDR handlers from
> other
> schedulers you just race here against them, e.g. you parked it now but
> another
> one in progress will unpark it as part of calling drm_sched_start for other
> rings[1]
> Unless I am missing something since I haven't found patch [1/2]
>
> [1] - https://elixir.bootlin.com/linux/latest/source/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c#L5041
You need to have your own wq and run all your tdr work on the same wq if
your reset has any cross-engine impact.
See
https://dri.freedesktop.org/docs/drm/gpu/drm-mm.html#c.drm_sched_backend_ops
for the ->timeout_job callback docs. I thought I brought this up already?
-Daniel
>
> Andrey
>
>
> > spin_lock(&sched->job_list_lock);
> > job = list_first_entry_or_null(&sched->pending_list,
> > struct drm_sched_job, list);
> > if (job) {
> > - /*
> > - * Remove the bad job so it cannot be freed by concurrent
> > - * drm_sched_cleanup_jobs. It will be reinserted back after sched->thread
> > - * is parked at which point it's safe.
> > - */
> > - list_del_init(&job->list);
> > spin_unlock(&sched->job_list_lock);
> > + /* vendor's timeout_job should call drm_sched_start() */
> > status = job->sched->ops->timedout_job(job);
> > /*
> > @@ -393,20 +391,6 @@ void drm_sched_stop(struct drm_gpu_scheduler *sched, struct drm_sched_job *bad)
> > kthread_park(sched->thread);
> > /*
> > - * Reinsert back the bad job here - now it's safe as
> > - * drm_sched_get_cleanup_job cannot race against us and release the
> > - * bad job at this point - we parked (waited for) any in progress
> > - * (earlier) cleanups and drm_sched_get_cleanup_job will not be called
> > - * now until the scheduler thread is unparked.
> > - */
> > - if (bad && bad->sched == sched)
> > - /*
> > - * Add at the head of the queue to reflect it was the earliest
> > - * job extracted.
> > - */
> > - list_add(&bad->list, &sched->pending_list);
> > -
> > - /*
> > * Iterate the job list from later to earlier one and either deactive
> > * their HW callbacks or remove them from pending list if they already
> > * signaled.
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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