linux-kernel - Re: [PATCH 6/6] cpuidle: Fix poll

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Date:   Tue, 24 Jan 2023 15:24:53 +0100
From:   "Rafael J. Wysocki" <rafael@...nel.org>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     mingo@...nel.org, will@...nel.org, boqun.feng@...il.com,
        mark.rutland@....com, tglx@...utronix.de, bp@...en8.de,
        dave.hansen@...ux.intel.com, x86@...nel.org, hpa@...or.com,
        seanjc@...gle.com, pbonzini@...hat.com, jgross@...e.com,
        srivatsa@...il.mit.edu, amakhalov@...are.com,
        pv-drivers@...are.com, rostedt@...dmis.org, mhiramat@...nel.org,
        wanpengli@...cent.com, vkuznets@...hat.com,
        boris.ostrovsky@...cle.com, rafael@...nel.org,
        daniel.lezcano@...aro.org, juri.lelli@...hat.com,
        vincent.guittot@...aro.org, dietmar.eggemann@....com,
        bsegall@...gle.com, mgorman@...e.de, bristot@...hat.com,
        vschneid@...hat.com, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org, virtualization@...ts.linux-foundation.org,
        linux-trace-kernel@...r.kernel.org, linux-pm@...r.kernel.org,
        kernel test robot <oliver.sang@...el.com>
Subject: Re: [PATCH 6/6] cpuidle: Fix poll_idle() noinstr annotation

On Mon, Jan 23, 2023 at 9:58 PM Peter Zijlstra <peterz@...radead.org> wrote:
>
> The instrumentation_begin()/end() annotations in poll_idle() were
> complete nonsense. Specifically they caused tracing to happen in the
> middle of noinstr code, resulting in RCU splats.
>
> Now that local_clock() is noinstr, mark up the rest and let it rip.
>
> Fixes: 00717eb8c955 ("cpuidle: Annotate poll_idle()")
> Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
> Reported-by: kernel test robot <oliver.sang@...el.com>
> Link: https://lore.kernel.org/oe-lkp/202301192148.58ece903-oliver.sang@intel.com

Acked-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>

> ---
>  drivers/cpuidle/cpuidle.c    |    2 +-
>  drivers/cpuidle/poll_state.c |    2 --
>  2 files changed, 1 insertion(+), 3 deletions(-)
>
> --- a/drivers/cpuidle/cpuidle.c
> +++ b/drivers/cpuidle/cpuidle.c
> @@ -426,7 +426,7 @@ void cpuidle_reflect(struct cpuidle_devi
>   * @dev:   the cpuidle device
>   *
>   */
> -u64 cpuidle_poll_time(struct cpuidle_driver *drv,
> +__cpuidle u64 cpuidle_poll_time(struct cpuidle_driver *drv,
>                       struct cpuidle_device *dev)
>  {
>         int i;
> --- a/drivers/cpuidle/poll_state.c
> +++ b/drivers/cpuidle/poll_state.c
> @@ -15,7 +15,6 @@ static int __cpuidle poll_idle(struct cp
>  {
>         u64 time_start;
>
> -       instrumentation_begin();
>         time_start = local_clock();
>
>         dev->poll_time_limit = false;
> @@ -42,7 +41,6 @@ static int __cpuidle poll_idle(struct cp
>         raw_local_irq_disable();
>
>         current_clr_polling();
> -       instrumentation_end();
>
>         return index;
>  }
>
>