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

From: neeraj . upadhyay
Date: Wed Oct 09 2024 - 08:56:38 EST


From: Neeraj Upadhyay <neeraj.upadhyay@xxxxxxxxxx>

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@xxxxxxxxxx>
Signed-off-by: Neeraj Upadhyay <neeraj.upadhyay@xxxxxxxxxx>
---
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