linux-kernel - Re: [RFC PATCH 12/19] cpufreq: fix locking of policy->rwsem in cpufreq_init

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Date:	Thu, 14 Jan 2016 17:58:32 +0000
From:	Juri Lelli <juri.lelli@....com>
To:	Viresh Kumar <viresh.kumar@...aro.org>
Cc:	linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org,
	peterz@...radead.org, rjw@...ysocki.net, mturquette@...libre.com,
	steve.muckle@...aro.org, vincent.guittot@...aro.org,
	morten.rasmussen@....com, dietmar.eggemann@....com
Subject: Re: [RFC PATCH 12/19] cpufreq: fix locking of policy->rwsem in
 cpufreq_init_policy

On 12/01/16 16:09, Viresh Kumar wrote:
> On 11-01-16, 17:35, Juri Lelli wrote:
> > There are paths in cpufreq_init_policy where policy is used, but its rwsem
> > is not held.
> > 
> > Fix it.
> > 
> > Cc: "Rafael J. Wysocki" <rjw@...ysocki.net>
> > Cc: Viresh Kumar <viresh.kumar@...aro.org>
> > Signed-off-by: Juri Lelli <juri.lelli@....com>
> > ---
> >  drivers/cpufreq/cpufreq.c | 11 ++++++++---
> >  1 file changed, 8 insertions(+), 3 deletions(-)
> > 
> > diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
> > index e7fc5c9..2c7cc6c73 100644
> > --- a/drivers/cpufreq/cpufreq.c
> > +++ b/drivers/cpufreq/cpufreq.c
> > @@ -998,21 +998,24 @@ static int cpufreq_add_policy_cpu(struct cpufreq_policy *policy, unsigned int cp
> >  {
> >  	int ret = 0;
> >  
> > +	down_write(&policy->rwsem);
> > +
> >  	/* Has this CPU been taken care of already? */
> > -	if (cpumask_test_cpu(cpu, policy->cpus))
> > +	if (cpumask_test_cpu(cpu, policy->cpus)) {
> > +		up_write(&policy->rwsem);
> 
> Perhaps create a label at the end to unlock the rwsem and jump to it?
> 

Yep, done.

Thanks,

- Juri