linux-kernel - Re: [PATCH v1 6/9] ACPI: processor: idle: Do not change power states if get power info failed

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Message-ID: <CAJZ5v0jBqPLjK2v7A-8Qd6ERhwz47jP3YCiTHJhD8vAgRHVjcQ@mail.gmail.com>
Date: Tue, 21 Oct 2025 21:49:01 +0200
From: "Rafael J. Wysocki" <rafael@...nel.org>
To: Huisong Li <lihuisong@...wei.com>
Cc: rafael@...nel.org, lenb@...nel.org, linux-acpi@...r.kernel.org, 
	linux-kernel@...r.kernel.org, Sudeep.Holla@....com, linuxarm@...wei.com, 
	jonathan.cameron@...wei.com, zhanjie9@...ilicon.com, zhenglifeng1@...wei.com, 
	yubowen8@...wei.com
Subject: Re: [PATCH v1 6/9] ACPI: processor: idle: Do not change power states
 if get power info failed

On Mon, Sep 29, 2025 at 11:38 AM Huisong Li <lihuisong@...wei.com> wrote:
>
> Driver will update power states when processor power states have been
> changed. To prevent any other abnormal issues, here add the verification
> for the result of getting power information, don't change power states
> and one error log when get power information failed.

But the old states may not be usable any more in that case.

If you want to check the acpi_processor_get_power_info(), it should
disable ACPi idle entirely on failures.

> Fixes: f427e5f1cf75 ("ACPI / processor: Get power info before updating the C-states")
> Signed-off-by: Huisong Li <lihuisong@...wei.com>
> ---
>  drivers/acpi/processor_idle.c | 15 ++++++++++-----
>  1 file changed, 10 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c
> index b0d6b51ee363..92b231f5d514 100644
> --- a/drivers/acpi/processor_idle.c
> +++ b/drivers/acpi/processor_idle.c
> @@ -1315,6 +1315,7 @@ int acpi_processor_power_state_has_changed(struct acpi_processor *pr)
>         int cpu;
>         struct acpi_processor *_pr;
>         struct cpuidle_device *dev;
> +       int ret = 0;
>
>         if (disabled_by_idle_boot_param())
>                 return 0;
> @@ -1344,16 +1345,20 @@ int acpi_processor_power_state_has_changed(struct acpi_processor *pr)
>                 }
>
>                 /* Populate Updated C-state information */
> -               acpi_processor_get_power_info(pr);
> -               acpi_processor_setup_cpuidle_states(pr);
> +               ret = acpi_processor_get_power_info(pr);
> +               if (ret)
> +                       pr_err("Get processor-%u power information failed.\n",
> +                              pr->id);
> +               else
> +                       acpi_processor_setup_cpuidle_states(pr);
>
>                 /* Enable all cpuidle devices */
>                 for_each_online_cpu(cpu) {
>                         _pr = per_cpu(processors, cpu);
>                         if (!_pr || !_pr->flags.power_setup_done)
>                                 continue;
> -                       acpi_processor_get_power_info(_pr);
> -                       if (_pr->flags.power) {
> +                       ret = acpi_processor_get_power_info(_pr);
> +                       if (!ret && _pr->flags.power) {
>                                 dev = per_cpu(acpi_cpuidle_device, cpu);
>                                 acpi_processor_setup_cpuidle_dev(_pr, dev);
>                                 cpuidle_enable_device(dev);
> @@ -1363,7 +1368,7 @@ int acpi_processor_power_state_has_changed(struct acpi_processor *pr)
>                 cpus_read_unlock();
>         }
>
> -       return 0;
> +       return ret;
>  }
>
>  void acpi_processor_register_idle_driver(void)
> --
> 2.33.0
>