linux-kernel - Re: [PATCH v3 02/12] ACPI: processor: thermal: Use scope-based cleanup helper

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Message-ID: <CAJZ5v0jxHQ3fBk_fSwg7QYsePvUyh=FDteyO+8F8oGfUwX2E9A@mail.gmail.com>
Date: Wed, 3 Sep 2025 13:07:27 +0200
From: "Rafael J. Wysocki" <rafael@...nel.org>
To: Zihuan Zhang <zhangzihuan@...inos.cn>
Cc: "Rafael J . wysocki" <rafael@...nel.org>, Viresh Kumar <viresh.kumar@...aro.org>, 
	Catalin Marinas <catalin.marinas@....com>, Will Deacon <will@...nel.org>, 
	Borislav Petkov <bp@...en8.de>, Dave Hansen <dave.hansen@...ux.intel.com>, 
	Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>, Michael Ellerman <mpe@...erman.id.au>, 
	Krzysztof Kozlowski <krzk@...nel.org>, Alim Akhtar <alim.akhtar@...sung.com>, 
	Thierry Reding <thierry.reding@...il.com>, MyungJoo Ham <myungjoo.ham@...sung.com>, 
	Kyungmin Park <kyungmin.park@...sung.com>, Chanwoo Choi <cw00.choi@...sung.com>, 
	Jani Nikula <jani.nikula@...ux.intel.com>, Rodrigo Vivi <rodrigo.vivi@...el.com>, 
	Tvrtko Ursulin <tursulin@...ulin.net>, David Airlie <airlied@...il.com>, 
	Simona Vetter <simona@...ll.ch>, Daniel Lezcano <daniel.lezcano@...nel.org>, 
	Sascha Hauer <s.hauer@...gutronix.de>, Shawn Guo <shawnguo@...nel.org>, 
	Eduardo Valentin <edubezval@...il.com>, Keerthy <j-keerthy@...com>, Ben Horgan <ben.horgan@....com>, 
	zhenglifeng <zhenglifeng1@...wei.com>, Zhang Rui <rui.zhang@...el.com>, 
	Len Brown <lenb@...nel.org>, Lukasz Luba <lukasz.luba@....com>, 
	Pengutronix Kernel Team <kernel@...gutronix.de>, Beata Michalska <beata.michalska@....com>, 
	Fabio Estevam <festevam@...il.com>, Pavel Machek <pavel@...nel.org>, Sumit Gupta <sumitg@...dia.com>, 
	Prasanna Kumar T S M <ptsm@...ux.microsoft.com>, Sudeep Holla <sudeep.holla@....com>, 
	Yicong Yang <yangyicong@...ilicon.com>, linux-pm@...r.kernel.org, 
	linux-acpi@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org, 
	linux-arm-kernel@...ts.infradead.org, intel-gfx@...ts.freedesktop.org, 
	dri-devel@...ts.freedesktop.org, imx@...ts.linux.dev, 
	linux-omap@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 02/12] ACPI: processor: thermal: Use scope-based
 cleanup helper

On Mon, Sep 1, 2025 at 10:58 AM Zihuan Zhang <zhangzihuan@...inos.cn> wrote:
>
> Replace the manual cpufreq_cpu_put() with __free(put_cpufreq_policy)
> annotation for policy references. This reduces the risk of reference
> counting mistakes and aligns the code with the latest kernel style.
>
> No functional change intended.
>
> Signed-off-by: Zihuan Zhang <zhangzihuan@...inos.cn>
> ---
>  drivers/acpi/processor_thermal.c | 18 ++++++------------
>  1 file changed, 6 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/acpi/processor_thermal.c b/drivers/acpi/processor_thermal.c
> index 1219adb11ab9..3c8b57df9619 100644
> --- a/drivers/acpi/processor_thermal.c
> +++ b/drivers/acpi/processor_thermal.c
> @@ -62,19 +62,14 @@ static int phys_package_first_cpu(int cpu)
>         return 0;
>  }
>
> -static int cpu_has_cpufreq(unsigned int cpu)
> +static bool cpu_has_cpufreq(unsigned int cpu)
>  {
> -       struct cpufreq_policy *policy;
> +       struct cpufreq_policy *policy __free(put_cpufreq_policy) = cpufreq_cpu_get(cpu);
>
>         if (!acpi_processor_cpufreq_init)
>                 return 0;
>
> -       policy = cpufreq_cpu_get(cpu);
> -       if (policy) {
> -               cpufreq_cpu_put(policy);
> -               return 1;
> -       }
> -       return 0;
> +       return !!policy;
>  }
>
>  static int cpufreq_get_max_state(unsigned int cpu)
> @@ -95,7 +90,6 @@ static int cpufreq_get_cur_state(unsigned int cpu)
>
>  static int cpufreq_set_cur_state(unsigned int cpu, int state)
>  {
> -       struct cpufreq_policy *policy;
>         struct acpi_processor *pr;
>         unsigned long max_freq;
>         int i, ret;
> @@ -111,6 +105,9 @@ static int cpufreq_set_cur_state(unsigned int cpu, int state)
>          * frequency.
>          */
>         for_each_online_cpu(i) {

I would still prefer the code below to be moved to a separate function
that would be called in each step of the for_each_online_cpu() loop.

> +               struct cpufreq_policy *policy __free(put_cpufreq_policy) =
> +                       cpufreq_cpu_get(i);
> +
>                 if (topology_physical_package_id(i) !=
>                     topology_physical_package_id(cpu))
>                         continue;
> @@ -120,15 +117,12 @@ static int cpufreq_set_cur_state(unsigned int cpu, int state)
>                 if (unlikely(!freq_qos_request_active(&pr->thermal_req)))
>                         continue;
>
> -               policy = cpufreq_cpu_get(i);
>                 if (!policy)
>                         return -EINVAL;
>
>                 max_freq = (policy->cpuinfo.max_freq *
>                             (100 - reduction_step(i) * cpufreq_thermal_reduction_pctg)) / 100;
>
> -               cpufreq_cpu_put(policy);
> -
>                 ret = freq_qos_update_request(&pr->thermal_req, max_freq);
>                 if (ret < 0) {
>                         pr_warn("Failed to update thermal freq constraint: CPU%d (%d)\n",
> --
> 2.25.1
>
>