linux-kernel - Re: [PATCH] cpufreq: Fix locking issues with governors

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Message-ID: <20200625135305.GB242742@google.com>
Date:   Thu, 25 Jun 2020 14:53:05 +0100
From:   Quentin Perret <qperret@...gle.com>
To:     "Rafael J. Wysocki" <rafael@...nel.org>
Cc:     Viresh Kumar <viresh.kumar@...aro.org>,
        Rafael Wysocki <rjw@...ysocki.net>,
        Linux PM <linux-pm@...r.kernel.org>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] cpufreq: Fix locking issues with governors

On Thursday 25 Jun 2020 at 15:32:43 (+0200), Rafael J. Wysocki wrote:
> On Thu, Jun 25, 2020 at 1:14 PM Quentin Perret <qperret@...gle.com> wrote:
> >
> > Hey Viresh
> >
> > On Thursday 25 Jun 2020 at 16:24:16 (+0530), Viresh Kumar wrote:
> > > The locking around governors handling isn't adequate currently. The list
> > > of governors should never be traversed without locking in place. Also we
> > > must make sure the governor isn't removed while it is still referenced
> > > by code.
> >
> > Thanks for having a look at this!
> >
> > This solves the issue for the reference to policy->last_governor, but
> > given that your patch is based on top of
> > 20200623142138.209513-3-qperret@...gle.com, 'default_governor' needs a
> > similar treatment I think.
> 
> So I would prefer to rebase the $subject patch from Viresh on top of
> the current mainline, apply it first and rebase the "default governor"
> series on top of it - and include the changes needed for the default
> governor handling in there.

Right, and Viresh's patch might be -stable material too? In any case,
making it standalone makes a lot of sense.

Thanks,
Quentin