Re: [PATCH v3 2/7] drm/sched: Add several job helpers to avoid drivers touching scheduler state

[Niranjana Vishwanathapura <niranjana.vishwanathapura@intel.com>]

On Thu, Oct 16, 2025 at 01:48:21PM -0700, Matthew Brost wrote:
>Add helpers to see if scheduler is stopped and a jobs signaled state.
>Expected to be used driver side on recovery and debug flows.
>
>Signed-off-by: Matthew Brost <matthew.brost@intel.com>
>---
> drivers/gpu/drm/scheduler/sched_main.c |  4 ++--
> include/drm/gpu_scheduler.h            | 32 ++++++++++++++++++++++++--
> 2 files changed, 32 insertions(+), 4 deletions(-)
>
>diff --git a/drivers/gpu/drm/scheduler/sched_main.c b/drivers/gpu/drm/scheduler/sched_main.c
>index 46119aacb809..69bd6e482268 100644
>--- a/drivers/gpu/drm/scheduler/sched_main.c
>+++ b/drivers/gpu/drm/scheduler/sched_main.c
>@@ -344,7 +344,7 @@ drm_sched_rq_select_entity_fifo(struct drm_gpu_scheduler *sched,
>  */
> static void drm_sched_run_job_queue(struct drm_gpu_scheduler *sched)
> {
>-	if (!READ_ONCE(sched->pause_submit))
>+	if (!drm_sched_is_stopped(sched))
> 		queue_work(sched->submit_wq, &sched->work_run_job);
> }
>
>@@ -354,7 +354,7 @@ static void drm_sched_run_job_queue(struct drm_gpu_scheduler *sched)
>  */
> static void drm_sched_run_free_queue(struct drm_gpu_scheduler *sched)
> {
>-	if (!READ_ONCE(sched->pause_submit))
>+	if (!drm_sched_is_stopped(sched))
> 		queue_work(sched->submit_wq, &sched->work_free_job);
> }
>
>diff --git a/include/drm/gpu_scheduler.h b/include/drm/gpu_scheduler.h
>index 7f31eba3bd61..d1a2d7f61c1d 100644
>--- a/include/drm/gpu_scheduler.h
>+++ b/include/drm/gpu_scheduler.h
>@@ -700,6 +700,17 @@ void drm_sched_entity_modify_sched(struct drm_sched_entity *entity,
>
> /* Inlines */
>
>+/**
>+ * drm_sched_is_stopped() - DRM is stopped
>+ * @sched: DRM scheduler
>+ *
>+ * Return: True if sched is stopped, False otherwise
>+ */
>+static inline bool drm_sched_is_stopped(struct drm_gpu_scheduler *sched)
>+{
>+	return READ_ONCE(sched->pause_submit);
>+}
>+
> /**
>  * struct drm_sched_pending_job_iter - DRM scheduler pending job iterator state
>  * @sched: DRM scheduler associated with pending job iterator
>@@ -716,7 +727,7 @@ __drm_sched_pending_job_iter_begin(struct drm_gpu_scheduler *sched)
> 		.sched = sched,
> 	};
>
>-	WARN_ON(!READ_ONCE(sched->pause_submit));
>+	WARN_ON(!drm_sched_is_stopped(sched));
> 	return iter;
> }

NIT...instead of modifying the functions added in previous patch, may be this
patch should go in first and the previous patch can be added after that with
drm_sched_is_stopped() usage?

>
>@@ -724,7 +735,7 @@ __drm_sched_pending_job_iter_begin(struct drm_gpu_scheduler *sched)
> static inline void
> __drm_sched_pending_job_iter_end(const struct drm_sched_pending_job_iter iter)
> {
>-	WARN_ON(!READ_ONCE(iter.sched->pause_submit));
>+	WARN_ON(!drm_sched_is_stopped(iter.sched));
> }
>
> DEFINE_CLASS(drm_sched_pending_job_iter, struct drm_sched_pending_job_iter,
>@@ -750,4 +761,21 @@ class_drm_sched_pending_job_iter_lock_ptr(class_drm_sched_pending_job_iter_t *_T
> 		list_for_each_entry((__job), &(__sched)->pending_list, list)	\
> 			for_each_if(!(__entity) || (__job)->entity == (__entity))
>
>+/**
>+ * drm_sched_job_is_signaled() - DRM scheduler job is signaled
>+ * @job: DRM scheduler job
>+ *
>+ * Determine if DRM scheduler job is signaled. DRM scheduler should be stopped
>+ * to obtain a stable snapshot of state.
>+ *
>+ * Return: True if job is signaled, False otherwise
>+ */
>+static inline bool drm_sched_job_is_signaled(struct drm_sched_job *job)
>+{
>+	struct drm_sched_fence *s_fence = job->s_fence;
>+
>+	WARN_ON(!drm_sched_is_stopped(job->sched));
>+	return dma_fence_is_signaled(&s_fence->finished);
>+}

NIT..In patch#4 where xe driver uses this function in couple places,
I am seeing originally it checks if the s_fence->parent is signaled
instead of &s_fence->finished as done here.
I do see below message in the 's_fence->parent' kernel-doc,
"We signal the &drm_sched_fence.finished fence once parent is signalled."
So, probably it is fine, but just want to ensure.

Niranjana

>+
> #endif
>-- 
>2.34.1
>