drm/sched: Add internal job peek/pop API

Idea is to add helpers for peeking and popping jobs from entities with
the goal of decoupling the hidden assumption in the code that queue_node
is the first element in struct drm_sched_job.

That assumption usually comes in the form of:

  while ((job = to_drm_sched_job(spsc_queue_pop(&entity->job_queue))))

Which breaks if the queue_node is re-positioned due to_drm_sched_job
being implemented with a container_of.

This also allows us to remove duplicate definitions of to_drm_sched_job.

Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@igalia.com>
Cc: Christian König <christian.koenig@amd.com>
Cc: Danilo Krummrich <dakr@kernel.org>
Cc: Matthew Brost <matthew.brost@intel.com>
Cc: Philipp Stanner <phasta@kernel.org>
Signed-off-by: Philipp Stanner <phasta@kernel.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20250221105038.79665-2-tvrtko.ursulin@igalia.com

1 files changed, 48 insertions, 0 deletions

diff --git a/drivers/gpu/drm/scheduler/sched_internal.h b/drivers/gpu/drm/scheduler/sched_internal.h
new file mode 100644
index 000000000000..bd34898911d7
--- /dev/null
+++ b/drivers/gpu/drm/scheduler/sched_internal.h
@@ -0,0 +1,48 @@
+/* SPDX-License-Identifier: MIT */
+
+#ifndef _DRM_GPU_SCHEDULER_INTERNAL_H_
+#define _DRM_GPU_SCHEDULER_INTERNAL_H_
+
+/**
+ * drm_sched_entity_queue_pop - Low level helper for popping queued jobs
+ *
+ * @entity: scheduler entity
+ *
+ * Low level helper for popping queued jobs.
+ *
+ * Returns: The job dequeued or NULL.
+ */
+static inline struct drm_sched_job *
+drm_sched_entity_queue_pop(struct drm_sched_entity *entity)
+{
+	struct spsc_node *node;
+
+	node = spsc_queue_pop(&entity->job_queue);
+	if (!node)
+		return NULL;
+
+	return container_of(node, struct drm_sched_job, queue_node);
+}
+
+/**
+ * drm_sched_entity_queue_peek - Low level helper for peeking at the job queue
+ *
+ * @entity: scheduler entity
+ *
+ * Low level helper for peeking at the job queue
+ *
+ * Returns: The job at the head of the queue or NULL.
+ */
+static inline struct drm_sched_job *
+drm_sched_entity_queue_peek(struct drm_sched_entity *entity)
+{
+	struct spsc_node *node;
+
+	node = spsc_queue_peek(&entity->job_queue);
+	if (!node)
+		return NULL;
+
+	return container_of(node, struct drm_sched_job, queue_node);
+}
+
+#endif