Crap, yeah indeed that needs to be protected by some lock.
Going to prepare a patch for that,
Christian.
Am 09.08.2018 um 21:49 schrieb Andrey Grodzovsky:
Reviewed-by: Andrey Grodzovsky <andrey.grodzov...@amd.com>
But I still have questions about entity->last_user (didn't notice
this before) -
Looks to me there is a race condition with it's current usage, let's
say process A was preempted after doing
drm_sched_entity_flush->cmpxchg(...)
now process B working on same entity (forked) is inside
drm_sched_entity_push_job, he writes his PID to entity->last_user and also
executes drm_sched_rq_add_entity. Now process A runs again and execute
drm_sched_rq_remove_entity inadvertently causing process B removal
from it's scheduler rq.
Looks to me like instead we should lock together entity->last_user
accesses and adds/removals of entity to the rq.
Andrey
On 08/06/2018 10:18 AM, Nayan Deshmukh wrote:
I forgot about this since we started discussing possible scenarios of
processes and threads.
In any case, this check is redundant. Acked-by: Nayan Deshmukh
<nayan26deshm...@gmail.com <mailto:nayan26deshm...@gmail.com>>
Nayan
On Mon, Aug 6, 2018 at 7:43 PM Christian König
<ckoenig.leichtzumer...@gmail.com
<mailto:ckoenig.leichtzumer...@gmail.com>> wrote:
Ping. Any objections to that?
Christian.
Am 03.08.2018 um 13:08 schrieb Christian König:
> That is superflous now.
>
> Signed-off-by: Christian König <christian.koe...@amd.com
<mailto:christian.koe...@amd.com>>
> ---
> drivers/gpu/drm/scheduler/gpu_scheduler.c | 5 -----
> 1 file changed, 5 deletions(-)
>
> diff --git a/drivers/gpu/drm/scheduler/gpu_scheduler.c
b/drivers/gpu/drm/scheduler/gpu_scheduler.c
> index 85908c7f913e..65078dd3c82c 100644
> --- a/drivers/gpu/drm/scheduler/gpu_scheduler.c
> +++ b/drivers/gpu/drm/scheduler/gpu_scheduler.c
> @@ -590,11 +590,6 @@ void drm_sched_entity_push_job(struct
drm_sched_job *sched_job,
> if (first) {
> /* Add the entity to the run queue */
> spin_lock(&entity->rq_lock);
> - if (!entity->rq) {
> - DRM_ERROR("Trying to push to a killed
entity\n");
> - spin_unlock(&entity->rq_lock);
> - return;
> - }
> drm_sched_rq_add_entity(entity->rq, entity);
> spin_unlock(&entity->rq_lock);
> drm_sched_wakeup(entity->rq->sched);
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