linux-kernel - Re: [PATCH V5] powercap/drivers/idle_injection: Add an idle injection framework

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Date:   Wed, 6 Jun 2018 14:23:57 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Daniel Lezcano <daniel.lezcano@...aro.org>
Cc:     rjw@...ysocki.net, linux-kernel@...r.kernel.org,
        Viresh Kumar <viresh.kumar@...aro.org>,
        Eduardo Valentin <edubezval@...il.com>,
        Javi Merino <javi.merino@...nel.org>,
        Leo Yan <leo.yan@...aro.org>,
        Kevin Wangtao <kevin.wangtao@...aro.org>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Rui Zhang <rui.zhang@...el.com>,
        Daniel Thompson <daniel.thompson@...aro.org>,
        "open list:POWER MANAGEMENT CORE" <linux-pm@...r.kernel.org>
Subject: Re: [PATCH V5] powercap/drivers/idle_injection: Add an idle
 injection framework

On Tue, Jun 05, 2018 at 11:16:40AM +0200, Daniel Lezcano wrote:
> +	atomic_t idle_duration_ms;
> +	atomic_t run_duration_ms;

> +	idle_duration_ms = atomic_read(&ii_dev->idle_duration_ms);

> +	run_duration_ms = atomic_read(&ii_dev->run_duration_ms);

> +	atomic_set(&ii_dev->run_duration_ms, run_duration_ms);
> +	atomic_set(&ii_dev->idle_duration_ms, idle_duration_ms);

> +	*run_duration_ms = atomic_read(&ii_dev->run_duration_ms);
> +	*idle_duration_ms = atomic_read(&ii_dev->idle_duration_ms);

> +	if (!atomic_read(&ii_dev->idle_duration_ms))

> +	if (!atomic_read(&ii_dev->run_duration_ms))

What is the point of atomic_t here ?!