linux-kernel - [PATCH 44/46] sched_ext: Factor out scx_link_sched() and scx_unlink

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Message-ID: <20250920005931.2753828-45-tj@kernel.org>
Date: Fri, 19 Sep 2025 14:59:07 -1000
From: Tejun Heo <tj@...nel.org>
To: void@...ifault.com,
	arighi@...dia.com,
	multics69@...il.com
Cc: linux-kernel@...r.kernel.org,
	sched-ext@...ts.linux.dev,
	memxor@...il.com,
	bpf@...r.kernel.org,
	Tejun Heo <tj@...nel.org>
Subject: [PATCH 44/46] sched_ext: Factor out scx_link_sched() and scx_unlink_sched()

Factor out scx_link_sched() and scx_unlink_sched() functions to reduce
code duplication in the scheduler enable/disable paths.

No functional change.

Signed-off-by: Tejun Heo <tj@...nel.org>
---
 kernel/sched/ext.c | 53 +++++++++++++++++++++++++++-------------------
 1 file changed, 31 insertions(+), 22 deletions(-)

diff --git a/kernel/sched/ext.c b/kernel/sched/ext.c
index 4558bec72508..058315fc524b 100644
--- a/kernel/sched/ext.c
+++ b/kernel/sched/ext.c
@@ -4221,6 +4221,33 @@ static void refresh_watchdog(void)
 		cancel_delayed_work_sync(&scx_watchdog_work);
 }
 
+static void scx_link_sched(struct scx_sched *sch)
+{
+	scoped_guard(raw_spinlock_irq, &scx_sched_lock) {
+#ifdef CONFIG_EXT_SUB_SCHED
+		struct scx_sched *parent = scx_parent(sch);
+		if (parent)
+			list_add_tail(&sch->sibling, &parent->children);
+#endif	/* CONFIG_EXT_SUB_SCHED */
+		list_add_tail_rcu(&sch->all, &scx_sched_all);
+	}
+
+	refresh_watchdog();
+}
+
+static void scx_unlink_sched(struct scx_sched *sch)
+{
+	scoped_guard(raw_spinlock_irq, &scx_sched_lock) {
+#ifdef CONFIG_EXT_SUB_SCHED
+		if (scx_parent(sch))
+			list_del_init(&sch->sibling);
+#endif	/* CONFIG_EXT_SUB_SCHED */
+		list_del_rcu(&sch->all);
+	}
+
+	refresh_watchdog();
+}
+
 #ifdef CONFIG_EXT_SUB_SCHED
 static DECLARE_WAIT_QUEUE_HEAD(scx_unlink_waitq);
 
@@ -4385,12 +4412,7 @@ static void scx_sub_disable(struct scx_sched *sch)
 	 */
 	synchronize_rcu_expedited();
 
-	raw_spin_lock_irq(&scx_sched_lock);
-	list_del_init(&sch->sibling);
-	list_del_rcu(&sch->all);
-	raw_spin_unlock_irq(&scx_sched_lock);
-
-	refresh_watchdog();
+	scx_unlink_sched(sch);
 
 	mutex_unlock(&scx_enable_mutex);
 
@@ -4549,11 +4571,7 @@ static void scx_root_disable(struct scx_sched *sch)
 	if (sch->ops.exit)
 		SCX_CALL_OP(sch, SCX_KF_UNLOCKED, exit, NULL, ei);
 
-	raw_spin_lock_irq(&scx_sched_lock);
-	list_del_rcu(&sch->all);
-	raw_spin_unlock_irq(&scx_sched_lock);
-
-	refresh_watchdog();
+	scx_unlink_sched(sch);
 
 	/*
 	 * scx_root clearing must be inside cpus_read_lock(). See
@@ -5215,11 +5233,7 @@ static int scx_root_enable(struct sched_ext_ops *ops, struct bpf_link *link)
 	 */
 	rcu_assign_pointer(scx_root, sch);
 
-	raw_spin_lock_irq(&scx_sched_lock);
-	list_add_tail_rcu(&sch->all, &scx_sched_all);
-	raw_spin_unlock_irq(&scx_sched_lock);
-
-	refresh_watchdog();
+	scx_link_sched(sch);
 
 	scx_idle_enable(ops);
 
@@ -5486,12 +5500,7 @@ static int scx_sub_enable(struct sched_ext_ops *ops, struct bpf_link *link)
 		goto out_put_cgrp;
 	}
 
-	raw_spin_lock_irq(&scx_sched_lock);
-	list_add_tail(&sch->sibling, &parent->children);
-	list_add_tail_rcu(&sch->all, &scx_sched_all);
-	raw_spin_unlock_irq(&scx_sched_lock);
-
-	refresh_watchdog();
+	scx_link_sched(sch);
 
 	if (sch->level >= SCX_SUB_MAX_DEPTH) {
 		scx_error(sch, "max nesting depth %d violated",
-- 
2.51.0