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

[Niranjana Vishwanathapura]

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.br...@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