From 5c9a9ca44fda41c5e82f50efced5297a9c19760d Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Tue, 24 May 2022 16:59:52 -0700 Subject: [PATCH] rcu-tasks: Idle tasks on offline CPUs are in quiescent states Any idle task corresponding to an offline CPU is in an RCU Tasks Trace quiescent state. This commit causes rcu_tasks_trace_postscan() to ignore idle tasks for offline CPUs, which it can do safely due to CPU-hotplug operations being disabled. Signed-off-by: Paul E. McKenney Cc: Neeraj Upadhyay Cc: Eric Dumazet Cc: Alexei Starovoitov Cc: Andrii Nakryiko Cc: Martin KaFai Lau Cc: KP Singh --- kernel/rcu/tasks.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/rcu/tasks.h b/kernel/rcu/tasks.h index 8fe78a7fecaf..ec68bfe98c95 100644 --- a/kernel/rcu/tasks.h +++ b/kernel/rcu/tasks.h @@ -1451,7 +1451,7 @@ static void rcu_tasks_trace_postscan(struct list_head *hop) { int cpu; - for_each_possible_cpu(cpu) + for_each_online_cpu(cpu) rcu_tasks_trace_pertask(idle_task(cpu), hop); // Re-enable CPU hotplug now that the tasklist scan has completed.