linux-kernel - Re: [RFC][PATCH 4/9] idle: Fix rcu_idle

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Message-ID: <YotX4ywdUPJt0lNW@BLR-5CG11610CF.amd.com>
Date:   Mon, 23 May 2022 15:16:11 +0530
From:   "Gautham R. Shenoy" <gautham.shenoy@....com>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     frederic@...nel.org, paulmck@...nel.org, rjw@...ysocki.net,
        x86@...nel.org, linux-kernel@...r.kernel.org, jpoimboe@...nel.org
Subject: Re: [RFC][PATCH 4/9] idle: Fix rcu_idle_*() usage

On Thu, May 19, 2022 at 11:27:54PM +0200, Peter Zijlstra wrote:
> The whole disable-RCU, enable-IRQS dance is very intricate since
> changing IRQ state is traced, which depends on RCU.
> 
> Add two helpers for the cpuidle case that mirror the entry code.
> 
> Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
> ---

[...]
>  
> --- a/drivers/cpuidle/cpuidle.c
> +++ b/drivers/cpuidle/cpuidle.c
> @@ -13,6 +13,7 @@
>  #include <linux/mutex.h>
>  #include <linux/sched.h>
>  #include <linux/sched/clock.h>
> +#include <linux/sched/idle.h>
>  #include <linux/notifier.h>
>  #include <linux/pm_qos.h>
>  #include <linux/cpu.h>
> @@ -150,12 +151,12 @@ static void enter_s2idle_proper(struct c
>  	 */
>  	stop_critical_timings();
>  	if (!(target_state->flags & CPUIDLE_FLAG_RCU_IDLE))
> -		rcu_idle_enter();
> +		cpuidle_rcu_enter();
>  	target_state->enter_s2idle(dev, drv, index);
>  	if (WARN_ON_ONCE(!irqs_disabled()))
> -		local_irq_disable();
> +		raw_local_irq_disable();
>  	if (!(target_state->flags & CPUIDLE_FLAG_RCU_IDLE))
> -		rcu_idle_exit();
> +		cpuidle_rcu_enter();

Shouldn't this be cpuidle_rcu_exit() ?


>  	tick_unfreeze();
>  	start_critical_timings();
>  

--
Thanks and Regards
gautham.