linux-kernel - Re: [PATCH V4 3/7] cpufreq: Remove cpufreq_governor

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Message-ID: <CAJZ5v0g=pu=KXHVjfiOdOca18CkNenzCQPb9a7cMdsy60fdwmw@mail.gmail.com>
Date:	Thu, 11 Feb 2016 10:53:43 +0100
From:	"Rafael J. Wysocki" <rafael@...nel.org>
To:	Viresh Kumar <viresh.kumar@...aro.org>
Cc:	Rafael Wysocki <rjw@...ysocki.net>,
	Juri Lelli <juri.lelli@....com>,
	Lists linaro-kernel <linaro-kernel@...ts.linaro.org>,
	"linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
	Shilpasri G Bhat <shilpa.bhat@...ux.vnet.ibm.com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH V4 3/7] cpufreq: Remove cpufreq_governor_lock

On Tue, Feb 9, 2016 at 4:46 AM, Viresh Kumar <viresh.kumar@...aro.org> wrote:
> We used to drop policy->rwsem just before calling __cpufreq_governor()
> in some cases earlier and so it was possible that __cpufreq_governor()
> runs concurrently via separate threads.
>
> In order to guarantee valid state transitions for governors,
> 'governor_enabled' was required to be protected using some locking and
> we created cpufreq_governor_lock for that.
>
> But now, __cpufreq_governor() is always called from within policy->rwsem
> held and so 'governor_enabled' is protected against races even without
> cpufreq_governor_lock.
>
> Get rid of the extra lock now.

This one looks good, but depends on the [2/7].

Thanks,
Rafael