linux-kernel - Re: [PATCH] cpufreq: stats: do cpufreq_cpu_put() corresponding to cpufreq_cpu

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Date:	Fri, 22 Mar 2013 12:59:42 +0100
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	Amit Kucheria <amit.kucheria@...aro.org>
Cc:	Viresh Kumar <viresh.kumar@...aro.org>,
	Robin Randhawa <robin.randhawa@....com>,
	linux-pm@...r.kernel.org, Liviu Dudau <Liviu.Dudau@....com>,
	linux-kernel@...r.kernel.org, cpufreq@...r.kernel.org,
	Steve Bannister <Steve.Bannister@....com>,
	Arvind Chauhan <arvind.chauhan@....com>,
	Lists linaro-kernel <linaro-kernel@...ts.linaro.org>,
	Charles Garcia-Tobin <charles.garcia-tobin@....com>
Subject: Re: [PATCH] cpufreq: stats: do cpufreq_cpu_put() corresponding to cpufreq_cpu_get

On Friday, March 22, 2013 04:42:57 PM Amit Kucheria wrote:
> On Fri, Mar 22, 2013 at 3:43 PM, Viresh Kumar <viresh.kumar@...aro.org> wrote:
> > In cpufreq_stats_free_sysfs() we aren't balancing calls to cpufreq_cpu_get()
> > with cpufreq_cpu_put(). This will never let us have ref count to policy->kobj as
> > zero.
> 
> Rafael,
> 
> Since this prevents booting on our hardware (we unregister and
> re-register the cpufreq driver to account for virtual cores), will
> this be considered as a hotfix for 3.9?

Sure.  Can you please remind me what hardware is that, though?

Rafael


> > Signed-off-by: Viresh Kumar <viresh.kumar@...aro.org>
> 
> Acked-by: Amit Kucheria <amit.kucheria@...aro.org>
> 
> > ---
> >  drivers/cpufreq/cpufreq_stats.c | 12 ++++++++----
> >  1 file changed, 8 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/cpufreq/cpufreq_stats.c b/drivers/cpufreq/cpufreq_stats.c
> > index 2fd779e..bfd6273 100644
> > --- a/drivers/cpufreq/cpufreq_stats.c
> > +++ b/drivers/cpufreq/cpufreq_stats.c
> > @@ -180,15 +180,19 @@ static void cpufreq_stats_free_sysfs(unsigned int cpu)
> >  {
> >         struct cpufreq_policy *policy = cpufreq_cpu_get(cpu);
> >
> > -       if (!cpufreq_frequency_get_table(cpu))
> > +       if (!policy)
> >                 return;
> >
> > -       if (policy && !policy_is_shared(policy)) {
> > +       if (!cpufreq_frequency_get_table(cpu))
> > +               goto put_ref;
> > +
> > +       if (!policy_is_shared(policy)) {
> >                 pr_debug("%s: Free sysfs stat\n", __func__);
> >                 sysfs_remove_group(&policy->kobj, &stats_attr_group);
> >         }
> > -       if (policy)
> > -               cpufreq_cpu_put(policy);
> > +
> > +put_ref:
> > +       cpufreq_cpu_put(policy);
> >  }
> >
> >  static int cpufreq_stats_create_table(struct cpufreq_policy *policy,
> > --
> > 1.7.12.rc2.18.g61b472e
> >
> --
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-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
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