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Date:	Tue, 1 May 2012 14:26:48 +0300
From:	Gilad Ben-Yossef <gilad@...yossef.com>
To:	Paul Mackerras <paulus@...ba.org>
Cc:	linux-kernel@...r.kernel.org, Rusty Russell <rusty@...tcorp.com.au>
Subject: Re: get/put_online_cpus documentation wrong?

On Tue, May 1, 2012 at 3:12 AM, Paul Mackerras <paulus@...ba.org> wrote:
>
> In Documentation/cpu-hotplug.txt it says:
>
> "       #include <linux/cpu.h>
>        get_online_cpus() and put_online_cpus():
>
> The above calls are used to inhibit cpu hotplug operations. While the
> cpu_hotplug.refcount is non zero, the cpu_online_mask will not change.
> If you merely need to avoid cpus going away, you could also use
> preempt_disable() and preempt_enable() for those sections.
> Just remember the critical section cannot call any
> function that can sleep or schedule this process away."


I *think* the critical section remark here is referring to using
preempt_disable/enable(),
rather  then the use of get/put_online_cpus().

Gilad


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Gilad Ben-Yossef
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 -- Jean-Baptiste Queru
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