From 955a0192082023bf08f1be279182090264cb2557 Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Wed, 18 May 2022 17:19:27 -0700 Subject: [PATCH] rcu-tasks: Stop RCU Tasks Trace from scanning idle tasks Now that RCU scans both running tasks and tasks that have blocked within their current RCU Tasks Trace read-side critical section, there is no need for it to scan the idle tasks. After all, an idle loop should not be remain within an RCU Tasks Trace read-side critical section across exit from idle, and from a BPF viewpoint, functions invoked from the idle loop should not sleep. So only running idle tasks can be within RCU Tasks Trace read-side critical sections. This commit therefore removes the scan of the idle tasks from the rcu_tasks_trace_postscan() function. 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 | 8 +------- 1 file changed, 1 insertion(+), 7 deletions(-) diff --git a/kernel/rcu/tasks.h b/kernel/rcu/tasks.h index d318cdfd2309c..272c905995e56 100644 --- a/kernel/rcu/tasks.h +++ b/kernel/rcu/tasks.h @@ -1533,16 +1533,10 @@ static void rcu_tasks_trace_pregp_step(struct list_head *hop) } /* - * Do intermediate processing between task and holdout scans and - * pick up the idle tasks. + * Do intermediate processing between task and holdout scans. */ static void rcu_tasks_trace_postscan(struct list_head *hop) { - int 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. cpus_read_unlock(); -- 2.30.2