linux-kernel - Re: [PATCH V3 2/3] thermal/drivers/cpu_cooling: Unregister with the policy

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Message-ID: <CAJZ5v0jFXmJ3ikEPQUp-cLv3+ZSnp1kP8CxdkZVofV1BS3+UwQ@mail.gmail.com>
Date:   Wed, 26 Jun 2019 11:06:38 +0200
From:   "Rafael J. Wysocki" <rafael@...nel.org>
To:     Viresh Kumar <viresh.kumar@...aro.org>
Cc:     Daniel Lezcano <daniel.lezcano@...aro.org>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Eduardo Valentin <edubezval@...il.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Sudeep Holla <sudeep.holla@....com>,
        Amit Daniel Kachhap <amit.kachhap@...il.com>,
        Javi Merino <javi.merino@...nel.org>,
        Zhang Rui <rui.zhang@...el.com>,
        Shawn Guo <shawnguo@...nel.org>,
        Sascha Hauer <s.hauer@...gutronix.de>,
        Pengutronix Kernel Team <kernel@...gutronix.de>,
        Fabio Estevam <festevam@...il.com>,
        NXP Linux Team <linux-imx@....com>,
        Keerthy <j-keerthy@...com>,
        "open list:CPU FREQUENCY DRIVERS - ARM BIG LITTLE" 
        <linux-pm@...r.kernel.org>,
        "moderated list:ARM/FREESCALE IMX / MXC ARM ARCHITECTURE" 
        <linux-arm-kernel@...ts.infradead.org>,
        "open list:TI BANDGAP AND THERMAL DRIVER" 
        <linux-omap@...r.kernel.org>
Subject: Re: [PATCH V3 2/3] thermal/drivers/cpu_cooling: Unregister with the policy

On Wed, Jun 26, 2019 at 8:37 AM Viresh Kumar <viresh.kumar@...aro.org> wrote:
>
> On 26-06-19, 08:02, Daniel Lezcano wrote:
> > On 26/06/2019 04:58, Viresh Kumar wrote:
> > > On 25-06-19, 13:32, Daniel Lezcano wrote:
> > >> diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
> > >> index aee024e42618..f07454249fbc 100644
> > >> --- a/drivers/cpufreq/cpufreq.c
> > >> +++ b/drivers/cpufreq/cpufreq.c
> > >> @@ -1379,8 +1379,8 @@ static int cpufreq_online(unsigned int cpu)
> > >>            cpufreq_driver->ready(policy);
> > >>
> > >>    if (cpufreq_thermal_control_enabled(cpufreq_driver))
> > >> -          policy->cdev = of_cpufreq_cooling_register(policy);
> > >> -
> > >> +          of_cpufreq_cooling_register(policy);
> > >> +
> > >
> > > We don't need any error checking here anymore ?
> >
> > There was no error checking initially. This comment and the others below
> > are for an additional patch IMO, not a change in this one.
>
> right, but ...
>
> > >> -void cpufreq_cooling_unregister(struct thermal_cooling_device *cdev)
> > >> +void cpufreq_cooling_unregister(struct cpufreq_policy *policy)
> > >>  {
> > >>    struct cpufreq_cooling_device *cpufreq_cdev;
> > >>    bool last;
> > >>
> > >> -  if (!cdev)
> > >> -          return;
>
> we used to return without any errors from here. Now we will have
> problems if regsitering fails for some reason.

Specifically, the last cpufreq_cdev in the list will be unregistered
AFAICS, and without removing it from the list for that matter, which
isn't what the caller wants.