linux-kernel - Re: [RFC PATCH 08/19] cpufreq: fix warning for cpufreq_init_policy unlocked access to cpufreq_governor

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Message-ID: <20160112100945.GZ1084@ubuntu>
Date:	Tue, 12 Jan 2016 15:39:45 +0530
From:	Viresh Kumar <viresh.kumar@...aro.org>
To:	Juri Lelli <juri.lelli@....com>
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 08/19] cpufreq: fix warning for cpufreq_init_policy
 unlocked access to cpufreq_governor_list

On 11-01-16, 17:35, Juri Lelli wrote:
> diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
> index 7dae7f3..d065435 100644
> --- a/drivers/cpufreq/cpufreq.c
> +++ b/drivers/cpufreq/cpufreq.c
> @@ -969,6 +969,7 @@ static int cpufreq_init_policy(struct cpufreq_policy *policy)
>  
>  	memcpy(&new_policy, policy, sizeof(*policy));
>  
> +	mutex_lock(&cpufreq_governor_mutex);
>  	/* Update governor of new_policy to the governor used before hotplug */
>  	gov = find_governor(policy->last_governor);

You should take the lock within find_governor() instead, i.e.  around
the while loop.

>  	if (gov)
> @@ -976,6 +977,7 @@ static int cpufreq_init_policy(struct cpufreq_policy *policy)
>  				policy->governor->name, policy->cpu);
>  	else
>  		gov = CPUFREQ_DEFAULT_GOVERNOR;
> +	mutex_unlock(&cpufreq_governor_mutex);
>  
>  	new_policy.governor = gov;
>  
> -- 
> 2.2.2

-- 
viresh