sched_ext: Factor out scx_dsq_list_node cursor initialization into INIT_DSQ_LIST_CURSOR

Factor out scx_dsq_list_node cursor initialization into INIT_DSQ_LIST_CURSOR
macro in preparation for additional users.

Reviewed-by: Emil Tsalapatis <emil@etsalapatis.com>
Cc: Dan Schatzberg <schatzberg.dan@gmail.com>
Acked-by: Andrea Righi <arighi@nvidia.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

Author: htejun

include/linux/sched/ext.h

@@ -149,6 +149,13 @@ struct scx_dsq_list_node {
 	u32			priv;		/* can be used by iter cursor */
 };
 
+#define INIT_DSQ_LIST_CURSOR(__node, __flags, __priv)				\
+	(struct scx_dsq_list_node) {						\
+		.node = LIST_HEAD_INIT((__node).node),				\
+		.flags = SCX_DSQ_LNODE_ITER_CURSOR | (__flags),			\
+		.priv = (__priv),						\
+	}
+
 /*
  * The following is embedded in task_struct and contains all fields necessary
  * for a task to be scheduled by SCX.

kernel/sched/ext.c

@@ -6253,9 +6253,8 @@ __bpf_kfunc int bpf_iter_scx_dsq_new(struct bpf_iter_scx_dsq *it, u64 dsq_id,
 	if (!kit->dsq)
 		return -ENOENT;
 
-	INIT_LIST_HEAD(&kit->cursor.node);
-	kit->cursor.flags = SCX_DSQ_LNODE_ITER_CURSOR | flags;
-	kit->cursor.priv = READ_ONCE(kit->dsq->seq);
+	kit->cursor = INIT_DSQ_LIST_CURSOR(kit->cursor, flags,
+					   READ_ONCE(kit->dsq->seq));
 
 	return 0;
 }