linux-kernel - Re: [PATCH v4 10/10] PM: EM: Use scope-based cleanup helper

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Message-ID: <34b5e01e-2f4a-4d57-93ca-ab4549681b17@kernel.org>
Date: Wed, 3 Sep 2025 15:21:48 +0200
From: Krzysztof Kozlowski <krzk@...nel.org>
To: Zihuan Zhang <zhangzihuan@...inos.cn>,
 "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>, 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>
Cc: 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 v4 10/10] PM: EM: Use scope-based cleanup helper

On 03/09/2025 15:17, Zihuan Zhang 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>
> ---
>  kernel/power/energy_model.c | 7 ++-----
>  1 file changed, 2 insertions(+), 5 deletions(-)
> 
> diff --git a/kernel/power/energy_model.c b/kernel/power/energy_model.c
> index ea7995a25780..99401678e809 100644
> --- a/kernel/power/energy_model.c
> +++ b/kernel/power/energy_model.c
> @@ -451,7 +451,7 @@ static void
>  em_cpufreq_update_efficiencies(struct device *dev, struct em_perf_state *table)
>  {
>  	struct em_perf_domain *pd = dev->em_pd;
> -	struct cpufreq_policy *policy;
> +	struct cpufreq_policy *policy __free(put_cpufreq_policy) = NULL;

This is not really correct coding style. Please read how to use
cleanup.h expressed in that header. You should have here proper
constructor or this should be moved. Or this should not be __free()...

>  	int found = 0;
>  	int i, cpu;
>  
> @@ -479,8 +479,6 @@ em_cpufreq_update_efficiencies(struct device *dev, struct em_perf_state *table)
>  			found++;
>  	}
>  
> -	cpufreq_cpu_put(policy);
> -
>  	if (!found)
>  		return;
>  
> @@ -787,7 +785,7 @@ static void em_check_capacity_update(void)
>  
>  	/* Check if CPUs capacity has changed than update EM */
>  	for_each_possible_cpu(cpu) {
> -		struct cpufreq_policy *policy;
> +		struct cpufreq_policy *policy __free(put_cpufreq_policy) = NULL;

Same problem here.

I don't think you really paid attention to my feedback last time.

Cleanup.h requires knowing what you do, not just blindly adding __free()
here and there.

Best regards,
Krzysztof