From 089254fd386eb6800dd7d7863f12a04ada0c35fa Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Wed, 3 Aug 2022 08:48:12 -0700 Subject: rcu: Document reason for rcu_all_qs() call to preempt_disable() Given that rcu_all_qs() is in non-preemptible kernels, why on earth should it invoke preempt_disable()? This commit adds the reason, which is to work nicely with debugging enabled in CONFIG_PREEMPT_COUNT=y kernels. Reported-by: Neeraj Upadhyay Reported-by: Boqun Feng Reported-by: Frederic Weisbecker Signed-off-by: Paul E. McKenney --- kernel/rcu/tree_plugin.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h index 4152816dd29f..c46b3c74dad1 100644 --- a/kernel/rcu/tree_plugin.h +++ b/kernel/rcu/tree_plugin.h @@ -870,7 +870,7 @@ void rcu_all_qs(void) if (!raw_cpu_read(rcu_data.rcu_urgent_qs)) return; - preempt_disable(); + preempt_disable(); // For CONFIG_PREEMPT_COUNT=y kernels /* Load rcu_urgent_qs before other flags. */ if (!smp_load_acquire(this_cpu_ptr(&rcu_data.rcu_urgent_qs))) { preempt_enable(); -- cgit v1.2.3-59-g8ed1b