[PATCH 1/2] drm/scheduler: only kill entity if last user is killed v2

[Nayan Deshmukh]

That makes sense. The change is Acked-by: Nayan Deshmukh <
nayan26deshmukh at gmail.com>

On Tue, Jul 31, 2018 at 2:12 AM Andrey Grodzovsky <Andrey.Grodzovsky at amd.com>
wrote:

> I believe that in this case
>
> if (!entity->rq) {
>
>     DRM_ERROR...
>
>     return;
>
> }
>
> clause will take place.
>
> P.S I remember we planned to actually propagate the error back to the
> caller so i guess we should take care of this sooner or later.
>
> The change is Reviewed-by: Andrey Grodzovsky <andrey.grodzovsky at amd.com>
> <andrey.grodzovsky at amd.com>
>
> Andrey
>
> On 07/30/2018 09:34 AM, Nayan Deshmukh wrote:
>
> Hi Christian,
>
> The code looks good to me. But I was just wondering what will happen when
> the last user is killed and some other user tries to push to the entity.
>
> Regards,
> Nayan Deshmukh
>
> On Mon, Jul 30, 2018 at 4:33 PM Christian König <
> ckoenig.leichtzumerken at gmail.com> wrote:
>
>> Note which task is using the entity and only kill it if the last user of
>> the entity is killed. This should prevent problems when entities are
>> leaked to
>> child processes.
>>
>> v2: add missing kernel doc
>>
>> Signed-off-by: Christian König <christian.koenig at amd.com>
>> ---
>>  drivers/gpu/drm/scheduler/gpu_scheduler.c | 6 +++++-
>>  include/drm/gpu_scheduler.h               | 2 ++
>>  2 files changed, 7 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/gpu/drm/scheduler/gpu_scheduler.c
>> b/drivers/gpu/drm/scheduler/gpu_scheduler.c
>> index 3f2fc5e8242a..f563e4fbb4b6 100644
>> --- a/drivers/gpu/drm/scheduler/gpu_scheduler.c
>> +++ b/drivers/gpu/drm/scheduler/gpu_scheduler.c
>> @@ -275,6 +275,7 @@ static void drm_sched_entity_kill_jobs_cb(struct
>> dma_fence *f,
>>  long drm_sched_entity_flush(struct drm_sched_entity *entity, long
>> timeout)
>>  {
>>         struct drm_gpu_scheduler *sched;
>> +       struct task_struct *last_user;
>>         long ret = timeout;
>>
>>         sched = entity->rq->sched;
>> @@ -295,7 +296,9 @@ long drm_sched_entity_flush(struct drm_sched_entity
>> *entity, long timeout)
>>
>>
>>         /* For killed process disable any more IBs enqueue right now */
>> -       if ((current->flags & PF_EXITING) && (current->exit_code ==
>> SIGKILL))
>> +       last_user = cmpxchg(&entity->last_user, current->group_leader,
>> NULL);
>> +       if ((!last_user || last_user == current->group_leader) &&
>> +           (current->flags & PF_EXITING) && (current->exit_code ==
>> SIGKILL))
>>                 drm_sched_entity_set_rq(entity, NULL);
>>
>>         return ret;
>> @@ -541,6 +544,7 @@ void drm_sched_entity_push_job(struct drm_sched_job
>> *sched_job,
>>
>>         trace_drm_sched_job(sched_job, entity);
>>
>> +       WRITE_ONCE(entity->last_user, current->group_leader);
>>         first = spsc_queue_push(&entity->job_queue,
>> &sched_job->queue_node);
>>
>>         /* first job wakes up scheduler */
>> diff --git a/include/drm/gpu_scheduler.h b/include/drm/gpu_scheduler.h
>> index 091b9afcd184..21c648b0b2a1 100644
>> --- a/include/drm/gpu_scheduler.h
>> +++ b/include/drm/gpu_scheduler.h
>> @@ -66,6 +66,7 @@ enum drm_sched_priority {
>>   * @guilty: points to ctx's guilty.
>>   * @fini_status: contains the exit status in case the process was
>> signalled.
>>   * @last_scheduled: points to the finished fence of the last scheduled
>> job.
>> + * @last_user: last group leader pushing a job into the entity.
>>   *
>>   * Entities will emit jobs in order to their corresponding hardware
>>   * ring, and the scheduler will alternate between entities based on
>> @@ -85,6 +86,7 @@ struct drm_sched_entity {
>>         struct dma_fence_cb             cb;
>>         atomic_t                        *guilty;
>>         struct dma_fence                *last_scheduled;
>> +       struct task_struct              *last_user;
>>  };
>>
>>  /**
>> --
>> 2.14.1
>>
>>
>
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