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

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Message-ID: <CAJZ5v0hisM6vfdNXaY7qCGtcMb1FENGxiBb=E=tkqDbRyjs=bA@mail.gmail.com>
Date: Wed, 3 Sep 2025 15:41:26 +0200
From: "Rafael J. Wysocki" <rafael@...nel.org>
To: Krzysztof Kozlowski <krzk@...nel.org>
Cc: 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>, 
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	Yicong Yang <yangyicong@...ilicon.com>, linux-pm@...r.kernel.org, 
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Subject: Re: [PATCH v4 10/10] PM: EM: Use scope-based cleanup helper

On Wed, Sep 3, 2025 at 3:22 PM Krzysztof Kozlowski <krzk@...nel.org> wrote:
>
> 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()...

I gather that this is what you mean (quoted verbatim from cleanup.h)

 * Given that the "__free(...) = NULL" pattern for variables defined at
 * the top of the function poses this potential interdependency problem
 * the recommendation is to always define and assign variables in one
 * statement and not group variable definitions at the top of the
 * function when __free() is used.

and thanks for pointing this out!