Re: [PATCH v2 14/44] cpuidle,cpu_pm: Remove RCU fiddling from cpu_pm_{enter,exit}()

Ulf Hansson
2022-10-04T11:05:55Z

On Mon, 19 Sept 2022 at 12:17, Peter Zijlstra <peterz@infradead.org> wrote:
>
> All callers should still have RCU enabled.
>
> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
> Acked-by: Mark Rutland <mark.rutland@arm.com>

Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org>

Kind regards
Uffe

> ---
> kernel/cpu_pm.c | 9 ---------
> 1 file changed, 9 deletions(-)
>
> --- a/kernel/cpu_pm.c
> +++ b/kernel/cpu_pm.c
> @@ -30,16 +30,9 @@ static int cpu_pm_notify(enum cpu_pm_eve
> {
> int ret;
>
> - /*
> - * This introduces a RCU read critical section, which could be
> - * disfunctional in cpu idle. Copy RCU_NONIDLE code to let RCU know
> - * this.
> - */
> - ct_irq_enter_irqson();
> rcu_read_lock();
> ret = raw_notifier_call_chain(&cpu_pm_notifier.chain, event, NULL);
> rcu_read_unlock();
> - ct_irq_exit_irqson();
>
> return notifier_to_errno(ret);
> }
> @@ -49,11 +42,9 @@ static int cpu_pm_notify_robust(enum cpu
> unsigned long flags;
> int ret;
>
> - ct_irq_enter_irqson();
> raw_spin_lock_irqsave(&cpu_pm_notifier.lock, flags);
> ret = raw_notifier_call_chain_robust(&cpu_pm_notifier.chain, event_up, event_down, NULL);
> raw_spin_unlock_irqrestore(&cpu_pm_notifier.lock, flags);
> - ct_irq_exit_irqson();
>
> return notifier_to_errno(ret);
> }
>
>