linux-kernel - Re: [PATCH 7/7] cpufreq: Exit governor when failed to start old governor

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Message-ID: <CAJZ5v0hizEYaJw77feqAoHJWYuANvbdxZ6BbogZ52sTU2eKTUA@mail.gmail.com>
Date: Mon, 23 Jun 2025 17:12:06 +0200
From: "Rafael J. Wysocki" <rafael@...nel.org>
To: Lifeng Zheng <zhenglifeng1@...wei.com>
Cc: rafael@...nel.org, viresh.kumar@...aro.org, ionela.voinescu@....com, 
	linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org, linuxarm@...wei.com, 
	jonathan.cameron@...wei.com, zhanjie9@...ilicon.com, lihuisong@...wei.com, 
	yubowen8@...wei.com
Subject: Re: [PATCH 7/7] cpufreq: Exit governor when failed to start old governor

On Mon, Jun 23, 2025 at 3:34 PM Lifeng Zheng <zhenglifeng1@...wei.com> wrote:
>
> Detect the result of starting old governor in cpufreq_set_policy(). If it
> fails, exit the governor and clear policy->governor.
>
> Signed-off-by: Lifeng Zheng <zhenglifeng1@...wei.com>
> ---
>  drivers/cpufreq/cpufreq.c | 8 +++++---
>  1 file changed, 5 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
> index 7b82ffb50283..2b431845a8a3 100644
> --- a/drivers/cpufreq/cpufreq.c
> +++ b/drivers/cpufreq/cpufreq.c
> @@ -2715,10 +2715,12 @@ static int cpufreq_set_policy(struct cpufreq_policy *policy,
>         pr_debug("starting governor %s failed\n", policy->governor->name);
>         if (old_gov) {
>                 policy->governor = old_gov;
> -               if (cpufreq_init_governor(policy))
> +               if (cpufreq_init_governor(policy)) {
>                         policy->governor = NULL;
> -               else
> -                       cpufreq_start_governor(policy);
> +               } else if (cpufreq_start_governor(policy)) {
> +                       cpufreq_exit_governor(policy);

This may introduce a governor module reference imbalance AFAICS.

> +                       policy->governor = NULL;
> +               }
>         }
>
>         return ret;
> --