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

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Message-ID: <CAJZ5v0h6iN_EQd6kMvYZjQwryF5cPo-EEXDFcJ6MK+k=24dr2Q@mail.gmail.com>
Date: Fri, 4 Jul 2025 11:48:52 +0200
From: "Rafael J. Wysocki" <rafael@...nel.org>
To: "zhenglifeng (A)" <zhenglifeng1@...wei.com>
Cc: "Rafael J. Wysocki" <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 Fri, Jul 4, 2025 at 11:38 AM zhenglifeng (A) <zhenglifeng1@...wei.com> wrote:
>
> On 2025/6/23 23:12, Rafael J. Wysocki wrote:
>
> > 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.
>
> Sorry, I don't really understand this. Could you explain more? Thanks.

It looks like I've confused cpufreq_start_governor() with
cpufreq_init_governor(), sorry for the noise.