linux-kernel - Re: [PATCH 2/4] base/drivers/arch_topology: Replace mutex with READ_ONCE / WRITE

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Message-ID: <20181123135807.GA14964@e107155-lin>
Date:   Fri, 23 Nov 2018 13:58:07 +0000
From:   Sudeep Holla <sudeep.holla@....com>
To:     Daniel Lezcano <daniel.lezcano@...aro.org>
Cc:     rjw@...ysocki.net, vincent.guittot@...aro.org,
        linux-kernel@...r.kernel.org,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Kate Stewart <kstewart@...uxfoundation.org>,
        Juri Lelli <juri.lelli@...hat.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        "Peter Zijlstra (Intel)" <peterz@...radead.org>
Subject: Re: [PATCH 2/4] base/drivers/arch_topology: Replace mutex with
 READ_ONCE / WRITE_ONCE

On Mon, Oct 29, 2018 at 05:23:18PM +0100, Daniel Lezcano wrote:
> The mutex protects a per_cpu variable access. The potential race can
> happen only when the cpufreq governor module is loaded and at the same
> time the cpu capacity is changed in the sysfs.
>

I wonder if we really need that sysfs entry to be writable. For some
reason, I had assumed it's read only, obviously it's not. I prefer to
make it RO if there's no strong reason other than debug purposes.

--
Regards,
Sudeep