Re: [PATCH 1/8] drm/sched: Add locking to drm_sched_entity_modify_sched

["Christian König" <ckoenig.leichtzumerken@gmail.com>]

Am 09.09.24 um 19:19 schrieb Tvrtko Ursulin:
> From: Tvrtko Ursulin <tvrtko.ursulin@igalia.com>
>
> Without the locking amdgpu currently can race between
> amdgpu_ctx_set_entity_priority() (via drm_sched_entity_modify_sched()) and
> drm_sched_job_arm(), leading to the latter accesing potentially
> inconsitent entity->sched_list and entity->num_sched_list pair.
>
> v2:
>   * Improve commit message. (Philipp)
>
> Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@igalia.com>
> Fixes: b37aced31eb0 ("drm/scheduler: implement a function to modify sched list")
> Cc: Christian König <christian.koenig@amd.com>
> Cc: Alex Deucher <alexander.deucher@amd.com>
> Cc: Luben Tuikov <ltuikov89@gmail.com>
> Cc: Matthew Brost <matthew.brost@intel.com>
> Cc: David Airlie <airlied@gmail.com>
> Cc: Daniel Vetter <daniel@ffwll.ch>
> Cc: dri-devel@lists.freedesktop.org
> Cc: Philipp Stanner <pstanner@redhat.com>
> Cc: <stable@vger.kernel.org> # v5.7+

Reviewed-by: Christian König <christian.koenig@amd.com>

> ---
>   drivers/gpu/drm/scheduler/sched_entity.c | 2 ++
>   1 file changed, 2 insertions(+)
>
> diff --git a/drivers/gpu/drm/scheduler/sched_entity.c b/drivers/gpu/drm/scheduler/sched_entity.c
> index 58c8161289fe..ae8be30472cd 100644
> --- a/drivers/gpu/drm/scheduler/sched_entity.c
> +++ b/drivers/gpu/drm/scheduler/sched_entity.c
> @@ -133,8 +133,10 @@ void drm_sched_entity_modify_sched(struct drm_sched_entity *entity,
>   {
>   	WARN_ON(!num_sched_list || !sched_list);
>   
> +	spin_lock(&entity->rq_lock);
>   	entity->sched_list = sched_list;
>   	entity->num_sched_list = num_sched_list;
> +	spin_unlock(&entity->rq_lock);
>   }
>   EXPORT_SYMBOL(drm_sched_entity_modify_sched);
>