linux-kernel - Re: [RFC PATCHC 2/3] idle: store the idle state the cpu is

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Message-ID: <20140415124330.GK11182@twins.programming.kicks-ass.net>
Date:	Tue, 15 Apr 2014 14:43:30 +0200
From:	Peter Zijlstra <peterz@...radead.org>
To:	Daniel Lezcano <daniel.lezcano@...aro.org>
Cc:	linux-kernel@...r.kernel.org, mingo@...e.hu, rjw@...ysocki.net,
	nicolas.pitre@...aro.org, linux-pm@...r.kernel.org,
	alex.shi@...aro.org, vincent.guittot@...aro.org,
	morten.rasmussen@....com
Subject: Re: [RFC PATCHC 2/3] idle: store the idle state the cpu is

On Fri, Mar 28, 2014 at 01:29:55PM +0100, Daniel Lezcano wrote:
> @@ -143,6 +145,10 @@ static int cpuidle_idle_call(void)
>  			if (!ret) {
>  				trace_cpu_idle_rcuidle(next_state, dev->cpu);
>  
> +				*power = &drv->states[next_state].power;
> +
> +				wmb();
> +

I very much suspect you meant: smp_wmb(), as I don't see the hardware
reading that pointer, therefore UP wouldn't care. Also, any and all
barriers should come with a comment that describes the data ordering and
points to the matchin barriers.
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