drm/sched: Re-order struct drm_sched_rq members for clarity

Current kerneldoc for struct drm_sched_rq incompletely documents what
fields are protected by the lock.

This is not good because it is misleading.

Lets fix it by listing all the elements which are protected by the lock.

While at it, lets also re-order the members so all protected by the lock
are in a single group.

v2:
 * Refer variables by kerneldoc syntax, more verbose commit text. (Philipp)

Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@igalia.com>
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: Philipp Stanner <pstanner@redhat.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Philipp Stanner <pstanner@redhat.com>
Signed-off-by: Philipp Stanner <pstanner@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20241016122013.7857-4-tursulin@igalia.com

include/drm/gpu_scheduler.h

@@ -243,21 +243,23 @@ struct drm_sched_entity {
 /**
  * struct drm_sched_rq - queue of entities to be scheduled.
  *
- * @lock: to modify the entities list.
  * @sched: the scheduler to which this rq belongs to.
- * @entities: list of the entities to be scheduled.
+ * @lock: protects @entities, @rb_tree_root and @current_entity.
  * @current_entity: the entity which is to be scheduled.
+ * @entities: list of the entities to be scheduled.
  * @rb_tree_root: root of time based priority queue of entities for FIFO scheduling
  *
  * Run queue is a set of entities scheduling command submissions for
  * one specific ring. It implements the scheduling policy that selects
  * the next entity to emit commands from.
  */
 struct drm_sched_rq {
-	spinlock_t			lock;
 	struct drm_gpu_scheduler	*sched;
-	struct list_head		entities;
+
+	spinlock_t			lock;
+	/* Following members are protected by the @lock: */
 	struct drm_sched_entity		*current_entity;
+	struct list_head		entities;
 	struct rb_root_cached		rb_tree_root;
 };