RE: [PATCH v2 linux-next 2/2] cpufreq: Convert the cpufreq_driver_lock to use the rcu

[Nathan Zimmer <nzimmer@sgi.com>]

Argh, your right.  I completely misread that section.
It'll take me a few days to respin and retest properly.

Thanks, 
Nate

________________________________________
From: Rafael J. Wysocki [rjw@sisk.pl]
Sent: Monday, February 11, 2013 1:36 PM
To: Nathan Zimmer
Cc: viresh.kumar@linaro.org; linux-kernel@vger.kernel.org; linux-pm@vger.kernel.org; cpufreq@vger.kernel.org
Subject: Re: [PATCH v2 linux-next 2/2] cpufreq: Convert the cpufreq_driver_lock to use the rcu

On Monday, February 11, 2013 05:13:30 PM Nathan Zimmer wrote:
> There are some spots that I need to give a much deeper review, cpufreq_register_driver for example.
>
> But I believe
> > @@ -196,7 +195,7 @@ static void __cpufreq_cpu_put(struct cpufreq_policy *data, bool sysfs)
> >  {
> >       if (!sysfs)
> >               kobject_put(&data->kobj);
> > -     module_put(cpufreq_driver->owner);
> > +     module_put(rcu_dereference(cpufreq_driver)->owner);
> >  }
> would be ok.  In the documentation whatisRCU.txt they give a very similar example.

Well, the very same document states the following:

        Note that the value returned by rcu_dereference() is valid
        only within the enclosing RCU read-side critical section.

Thanks,
Rafael


--
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.