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Date:   Tue, 19 Jun 2018 16:21:16 +0200
From:   Peter Zijlstra <peterz@infradead.org>
To:     Quentin Perret <quentin.perret@arm.com>
Cc:     rjw@rjwysocki.net, gregkh@linuxfoundation.org,
        linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org,
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Subject: Re: [RFC PATCH v3 03/10] PM: Introduce an Energy Model management
 framework
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On Tue, Jun 19, 2018 at 04:16:42PM +0200, Peter Zijlstra wrote:
> On Tue, Jun 19, 2018 at 02:38:45PM +0100, Quentin Perret wrote:
> > But maybe I could use something simpler than a lock in this case ?
> > Would WRITE_ONCE/READ_ONCE be enough to ensure that atomicity for
> > example ?
> 
> Yes, since its a single pointer, smp_store_release() + READ_ONCE()
> should be sufficient (these are the foundations of RCU).

Note that per_cpu()/this_cpu_read() and friends should imply READ_ONCE().