linux-kernel - Re: [PATCH] cpuidle: haltpoll: Do not enable interrupts when entering idle

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Date: Fri, 29 Dec 2023 18:12:36 +0100
From: "Rafael J. Wysocki" <rafael@...nel.org>
To: "Borislav Petkov (AMD)" <bp@...en8.de>
Cc: linux-pm@...r.kernel.org, forza@...nline.net, 
	"Rafael J. Wysocki" <rafael@...nel.org>, Daniel Lezcano <daniel.lezcano@...aro.org>, 
	lkml <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] cpuidle: haltpoll: Do not enable interrupts when entering idle

On Thu, Dec 28, 2023 at 3:54 PM Borislav Petkov (AMD) <bp@...en8.de> wrote:
>
> Hi,
>
> I think PeterZ's massaging from
>
>   https://lore.kernel.org/all/20230112194314.845371875@infradead.org/
>
> missed one.
>
> @Forza, if you want to have your real name in the patch tags below and
> thus be part of git history, lemme know. If you don't want them there,
> either.
>
> Thx.
>
> ---
> From: Borislav Petkov (AMD) <bp@...en8.de>

I would have appreciated a Subject: line here.

>
> The cpuidle governors' ->enter() methods are supposed to be IRQ
> invariant:

cpuidle governors have no ->enter() callbacks, drivers do.  And this
particular haltpoll is a driver (there is a haltpoll governor too,
confusingly enough).

>
>   5e26aa933911 ("cpuidle/poll: Ensure IRQs stay disabled after cpuidle_state::enter() calls")
>   bb7b11258561 ("cpuidle: Move IRQ state validation")
>
> Do that in the haltpoll governor too.

And so s/governor/driver/ here.

> Fixes: 5e26aa933911 ("cpuidle/poll: Ensure IRQs stay disabled after cpuidle_state::enter() calls")
> Closes: https://bugzilla.kernel.org/show_bug.cgi?id=218245
> Reported-by: <forza@...nline.net>
> Tested-by: <forza@...nline.net>
> Signed-off-by: Borislav Petkov (AMD) <bp@...en8.de>

Nevertheless, applied (with the changelog adjustments mentioned above).

> ---
>  drivers/cpuidle/cpuidle-haltpoll.c | 9 ++++-----
>  1 file changed, 4 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/cpuidle/cpuidle-haltpoll.c b/drivers/cpuidle/cpuidle-haltpoll.c
> index e66df22f9695..d8515d5c0853 100644
> --- a/drivers/cpuidle/cpuidle-haltpoll.c
> +++ b/drivers/cpuidle/cpuidle-haltpoll.c
> @@ -25,13 +25,12 @@ MODULE_PARM_DESC(force, "Load unconditionally");
>  static struct cpuidle_device __percpu *haltpoll_cpuidle_devices;
>  static enum cpuhp_state haltpoll_hp_state;
>
> -static int default_enter_idle(struct cpuidle_device *dev,
> -                             struct cpuidle_driver *drv, int index)
> +static __cpuidle int default_enter_idle(struct cpuidle_device *dev,
> +                                       struct cpuidle_driver *drv, int index)
>  {
> -       if (current_clr_polling_and_test()) {
> -               local_irq_enable();
> +       if (current_clr_polling_and_test())
>                 return index;
> -       }
> +
>         arch_cpu_idle();
>         return index;
>  }
> --
> 2.42.0.rc0.25.ga82fb66fed25
>
>
> --
> Regards/Gruss,
>     Boris.
>
> https://people.kernel.org/tglx/notes-about-netiquette