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: <20160113060746.GI6050@ubuntu>
Date:	Wed, 13 Jan 2016 11:37:46 +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 12-01-16, 15:52, Juri Lelli wrote:
> Other users (i.e., cpufreq_parse_governor and cpufreq_register_governor)
> needs to take the mutex externally. So, we need to unify this behaviour.

No they don't have to.

And that's why I have been saying that we better nail down the exact
thing the mutex is supposed to protect.

There can be two cases here:
- It protects the governor list, in that case we can move it to
  find_governor().
- It guarantees that the governor pointer stays valid: That's not true
  as we are using the governor pointer outside of the lock.

And so I said, "No they don't have to" :)

-- 
viresh