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Subject: Re: [PATCH] CPU hotplug, freezer: Fix bugs in CPU hotplug call path
From: Peter Zijlstra <a.p.zijlstra@chello.nl>
To: "Srivatsa S. Bhat" <srivatsa.bhat@linux.vnet.ibm.com>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>, pavel@ucw.cz, len.brown@intel.com,
        mingo@elte.hu, akpm@linux-foundation.org, suresh.b.siddha@intel.com,
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        rusty@rustcorp.com.au, vatsa@linux.vnet.ibm.com, ashok.raj@intel.com,
        linux-kernel@vger.kernel.org
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Date: Mon, 03 Oct 2011 12:03:35 +0200
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On Mon, 2011-10-03 at 01:14 +0530, Srivatsa S. Bhat wrote:
> +static atomic_t tasks_frozen = ATOMIC_INIT(0);
> +
> +void set_tasks_frozen_flag(void)
> +{
> +       atomic_set(&tasks_frozen, 1);
> +}
> +
> +void clear_tasks_frozen_flag(void)
> +{
> +       atomic_set(&tasks_frozen, 0);
> +}
> +
> +int tasks_are_frozen(void)
> +{
> +       int ret;
> +       ret = atomic_read(&tasks_frozen);
> +       return ret;
> +} 

What's the point of using atomic_t here? Neither set nor read are
actually atomic ops.