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

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Message-ID: <9cea4556-15f8-9377-305a-b629ba7e811f@linaro.org>
Date:   Fri, 23 Nov 2018 17:04:18 +0100
From:   Daniel Lezcano <daniel.lezcano@...aro.org>
To:     Sudeep Holla <sudeep.holla@....com>
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 23/11/2018 14:58, Sudeep Holla wrote:
> 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.

Are you suggesting to remove the READ_ONCE/WRITE_ONCE patch and set the
sysfs file read-only ?


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