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

From: "Rafael J. Wysocki" <rafael@kernel.org>
To: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>,
	"Rafael J. Wysocki" <rjw@rjwysocki.net>,
	Eduardo Valentin <edubezval@gmail.com>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Sudeep Holla <sudeep.holla@arm.com>,
	Amit Daniel Kachhap <amit.kachhap@gmail.com>,
	Javi Merino <javi.merino@kernel.org>,
	Zhang Rui <rui.zhang@intel.com>, Shawn Guo <shawnguo@kernel.org>,
	Sascha Hauer <s.hauer@pengutronix.de>,
	Pengutronix Kernel Team <kernel@pengutronix.de>,
	Fabio Estevam <festevam@gmail.com>,
	NXP Linux Team <linux-imx@nxp.com>, Keerthy <j-keerthy@ti.com>,
	"open list:CPU FREQUENCY DRIVERS - ARM BIG LITTLE" 
	<linux-pm@vger.kernel.org>,
	"moderated list:ARM/FREESCALE IMX / MXC ARM ARCHITECTURE" 
	<linux-arm-kernel@lists.infradead.org>,
	"open list:TI BANDGAP AND THERMAL DRIVER" 
	<linux-omap@vger.kernel.org>
Subject: Re: [PATCH V3 2/3] thermal/drivers/cpu_cooling: Unregister with the policy
Date: Wed, 26 Jun 2019 11:06:38 +0200	[thread overview]
Message-ID: <CAJZ5v0jFXmJ3ikEPQUp-cLv3+ZSnp1kP8CxdkZVofV1BS3+UwQ@mail.gmail.com> (raw)
In-Reply-To: <20190626063716.cechnzsb75q5lclr@vireshk-i7>

On Wed, Jun 26, 2019 at 8:37 AM Viresh Kumar <viresh.kumar@linaro.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.