linux-kernel - [PATCH rcu 05/10] rcu: Move kthread_prio bounds-check to a separate function

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Message-Id: <20220204232406.814-5-paulmck@kernel.org>
Date:   Fri,  4 Feb 2022 15:24:01 -0800
From:   "Paul E. McKenney" <paulmck@...nel.org>
To:     rcu@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org, kernel-team@...com,
        rostedt@...dmis.org, Alison Chaiken <achaiken@...ora.tech>,
        "Paul E . McKenney" <paulmck@...nel.org>
Subject: [PATCH rcu 05/10] rcu: Move kthread_prio bounds-check to a separate function

From: Alison Chaiken <achaiken@...ora.tech>

Move the bounds-check of the kthread_prio cmdline parameter to a new
function in order to faciliate a different callsite.

Signed-off-by: Alison Chaiken <achaiken@...ora.tech>
Signed-off-by: Paul E. McKenney <paulmck@...nel.org>
---
 kernel/rcu/tree.c | 39 +++++++++++++++++++++++----------------
 1 file changed, 23 insertions(+), 16 deletions(-)

diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 4e5e37e5ee3c9..5bf0312f66760 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -4440,26 +4440,10 @@ static int rcu_pm_notify(struct notifier_block *self,
 static int __init rcu_spawn_gp_kthread(void)
 {
 	unsigned long flags;
-	int kthread_prio_in = kthread_prio;
 	struct rcu_node *rnp;
 	struct sched_param sp;
 	struct task_struct *t;
 
-	/* Force priority into range. */
-	if (IS_ENABLED(CONFIG_RCU_BOOST) && kthread_prio < 2
-	    && IS_BUILTIN(CONFIG_RCU_TORTURE_TEST))
-		kthread_prio = 2;
-	else if (IS_ENABLED(CONFIG_RCU_BOOST) && kthread_prio < 1)
-		kthread_prio = 1;
-	else if (kthread_prio < 0)
-		kthread_prio = 0;
-	else if (kthread_prio > 99)
-		kthread_prio = 99;
-
-	if (kthread_prio != kthread_prio_in)
-		pr_alert("rcu_spawn_gp_kthread(): Limited prio to %d from %d\n",
-			 kthread_prio, kthread_prio_in);
-
 	rcu_scheduler_fully_active = 1;
 	t = kthread_create(rcu_gp_kthread, NULL, "%s", rcu_state.name);
 	if (WARN_ONCE(IS_ERR(t), "%s: Could not start grace-period kthread, OOM is now expected behavior\n", __func__))
@@ -4584,6 +4568,28 @@ static void __init rcu_init_one(void)
 	}
 }
 
+/*
+ * Force priority from the kernel command-line into range.
+ */
+static void __init sanitize_kthread_prio(void)
+{
+	int kthread_prio_in = kthread_prio;
+
+	if (IS_ENABLED(CONFIG_RCU_BOOST) && kthread_prio < 2
+	    && IS_BUILTIN(CONFIG_RCU_TORTURE_TEST))
+		kthread_prio = 2;
+	else if (IS_ENABLED(CONFIG_RCU_BOOST) && kthread_prio < 1)
+		kthread_prio = 1;
+	else if (kthread_prio < 0)
+		kthread_prio = 0;
+	else if (kthread_prio > 99)
+		kthread_prio = 99;
+
+	if (kthread_prio != kthread_prio_in)
+		pr_alert("%s: Limited prio to %d from %d\n",
+			 __func__, kthread_prio, kthread_prio_in);
+}
+
 /*
  * Compute the rcu_node tree geometry from kernel parameters.  This cannot
  * replace the definitions in tree.h because those are needed to size
@@ -4744,6 +4750,7 @@ void __init rcu_init(void)
 
 	kfree_rcu_batch_init();
 	rcu_bootup_announce();
+	sanitize_kthread_prio();
 	rcu_init_geometry();
 	rcu_init_one();
 	if (dump_tree)
-- 
2.31.1.189.g2e36527f23