Re: [PATCH] drm/amdgpu: guard ib scheduling while in reset

["Grodzovsky, Andrey" <Andrey.Grodzovsky-5C7GfCeVMHo@public.gmane.org>]

Can you elaborate on what is the tricky part with the lock ? I assumed 
we just use per scheduler lock.

Andrey

On 10/30/19 10:50 AM, Christian König wrote:
> A lock inside the scheduler is rather tricky to implement.
>
> What you need to do is to get rid of the park()/unpark() hack in 
> drm_sched_entity_fini().
>
> We could do this with a struct completion or convert the scheduler 
> from a thread to a work item.
>
> Regards,
> Christian.
>
> Am 30.10.19 um 15:44 schrieb Grodzovsky, Andrey:
>> That good  as proof of RCA but I still think we should grab a dedicated
>> lock inside scheduler since the race is internal to scheduler code so
>> this better to handle it inside the scheduler code to make the fix apply
>> for all drivers using it.
>>
>> Andrey
>>
>> On 10/30/19 4:44 AM, S, Shirish wrote:
>>>>>> We still have it and isn't doing kthread_park()/unpark() from
>>>>>> drm_sched_entity_fini while GPU reset in progress defeats all the
>>>>>> purpose of drm_sched_stop->kthread_park ? If
>>>>>> drm_sched_entity_fini-> kthread_unpark happens AFTER
>>>>>> drm_sched_stop->kthread_park nothing prevents from another (third)
>>>>>> thread keep submitting job to HW which will be picked up by the
>>>>>> unparked scheduler thread try to submit to HW but fail because the
>>>>>> HW ring is deactivated.
>>>>>>
>>>>>> If so maybe we should serialize calls to
>>>>>> kthread_park/unpark(sched->thread) ?
>>>>>>
>>>>> Yeah, that was my thinking as well. Probably best to just grab the
>>>>> reset lock before calling drm_sched_entity_fini().
>>>>
>>>> Shirish - please try locking &adev->lock_reset around calls to
>>>> drm_sched_entity_fini as Christian suggests and see if this actually
>>>> helps the issue.
>>>>
>>> Yes that also works.
>>>
>>> Regards,
>>>
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