linux-kernel - [PATCH v2 03/10] rcu/tasks: Move holdout checks for idle task to a separate function

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Message-Id: <20241009125127.18902-4-neeraj.upadhyay@kernel.org>
Date: Wed,  9 Oct 2024 18:21:20 +0530
From: neeraj.upadhyay@...nel.org
To: rcu@...r.kernel.org
Cc: linux-kernel@...r.kernel.org,
	paulmck@...nel.org,
	joel@...lfernandes.org,
	frederic@...nel.org,
	boqun.feng@...il.com,
	urezki@...il.com,
	rostedt@...dmis.org,
	mathieu.desnoyers@...icios.com,
	jiangshanlai@...il.com,
	qiang.zhang1211@...il.com,
	peterz@...radead.org,
	neeraj.upadhyay@....com,
	Neeraj Upadhyay <neeraj.upadhyay@...nel.org>
Subject: [PATCH v2 03/10] rcu/tasks: Move holdout checks for idle task to a separate function

From: Neeraj Upadhyay <neeraj.upadhyay@...nel.org>

Move checks for an idle task being a holdout task for RCU-tasks
to a separate function - rcu_idle_task_is_holdout(). This function
will be used in subsequent commits to add additional checks for
idle task. No functional change intended.

Suggested-by: Frederic Weisbecker <frederic@...nel.org>
Signed-off-by: Neeraj Upadhyay <neeraj.upadhyay@...nel.org>
---
 kernel/rcu/tasks.h | 14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

diff --git a/kernel/rcu/tasks.h b/kernel/rcu/tasks.h
index 6333f4ccf024..56015ced3f37 100644
--- a/kernel/rcu/tasks.h
+++ b/kernel/rcu/tasks.h
@@ -976,6 +976,15 @@ static void rcu_tasks_pregp_step(struct list_head *hop)
 	synchronize_rcu();
 }
 
+static bool rcu_idle_task_is_holdout(struct task_struct *t, int cpu)
+{
+	/* Idle tasks on offline CPUs are RCU-tasks quiescent states. */
+	if (!rcu_cpu_online(cpu))
+		return false;
+
+	return true;
+}
+
 /* Check for quiescent states since the pregp's synchronize_rcu() */
 static bool rcu_tasks_is_holdout(struct task_struct *t)
 {
@@ -995,9 +1004,8 @@ static bool rcu_tasks_is_holdout(struct task_struct *t)
 
 	cpu = task_cpu(t);
 
-	/* Idle tasks on offline CPUs are RCU-tasks quiescent states. */
-	if (t == idle_task(cpu) && !rcu_cpu_online(cpu))
-		return false;
+	if (t == idle_task(cpu))
+		return rcu_idle_task_is_holdout(t, cpu);
 
 	return true;
 }
-- 
2.40.1