[PATCH] cpuidle: Drop misleading comments about RCU usage

[Rafael J. Wysocki]

On Tue, Sep 22, 2020 at 11:16 AM Ulf Hansson <ulf.hansson at linaro.org> wrote:
>
> The commit 1098582a0f6c ("sched,idle,rcu: Push rcu_idle deeper into the
> idle path"), moved the calls rcu_idle_enter|exit() into the cpuidle core.
>
> However, it forgot to remove a couple of comments in enter_s2idle_proper()
> about why RCU_NONIDLE earlier was needed. So, let's drop them as they have
> become a bit misleading.
>
> Cc: Peter Zijlstra (Intel) <peterz at infradead.org>
> Signed-off-by: Ulf Hansson <ulf.hansson at linaro.org>

Applied as 5.9-rc7 material, thanks!

> ---
>  drivers/cpuidle/cpuidle.c | 10 ----------
>  1 file changed, 10 deletions(-)
>
> diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c
> index 6c7e5621cf9a..29e84687f3c3 100644
> --- a/drivers/cpuidle/cpuidle.c
> +++ b/drivers/cpuidle/cpuidle.c
> @@ -142,11 +142,6 @@ static void enter_s2idle_proper(struct cpuidle_driver *drv,
>
>         time_start = ns_to_ktime(local_clock());
>
> -       /*
> -        * trace_suspend_resume() called by tick_freeze() for the last CPU
> -        * executing it contains RCU usage regarded as invalid in the idle
> -        * context, so tell RCU about that.
> -        */
>         tick_freeze();
>         /*
>          * The state used here cannot be a "coupled" one, because the "coupled"
> @@ -159,11 +154,6 @@ static void enter_s2idle_proper(struct cpuidle_driver *drv,
>         target_state->enter_s2idle(dev, drv, index);
>         if (WARN_ON_ONCE(!irqs_disabled()))
>                 local_irq_disable();
> -       /*
> -        * timekeeping_resume() that will be called by tick_unfreeze() for the
> -        * first CPU executing it calls functions containing RCU read-side
> -        * critical sections, so tell RCU about that.
> -        */
>         if (!(target_state->flags & CPUIDLE_FLAG_RCU_IDLE))
>                 rcu_idle_exit();
>         tick_unfreeze();
> --
> 2.25.1
>