linux-kernel - Re: [RFC PATCH 07/19] cpufreq: assert locking when accessing cpufreq_governor

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Message-ID: <20160112100122.GY1084@ubuntu>
Date:	Tue, 12 Jan 2016 15:31:22 +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 07/19] cpufreq: assert locking when accessing
 cpufreq_governor_list

On 11-01-16, 17:35, Juri Lelli wrote:
> @@ -2025,6 +2027,7 @@ int cpufreq_register_governor(struct cpufreq_governor *governor)
>  	err = -EBUSY;
>  	if (!find_governor(governor->name)) {
>  		err = 0;
> +		lockdep_assert_held(&cpufreq_governor_mutex);
>  		list_add(&governor->governor_list, &cpufreq_governor_list);
>  	}

Why here? This is how the routine looks like:

int cpufreq_register_governor(struct cpufreq_governor *governor)
{
	int err;

	if (!governor)
		return -EINVAL;

	if (cpufreq_disabled())
		return -ENODEV;

	mutex_lock(&cpufreq_governor_mutex);

	governor->initialized = 0;
	err = -EBUSY;
	if (!find_governor(governor->name)) {
		err = 0;
		list_add(&governor->governor_list, &cpufreq_governor_list);
	}

	mutex_unlock(&cpufreq_governor_mutex);
	return err;
}


-- 
viresh