Re: [RFC PATCH v3 03/10] PM: Introduce an Energy Model management framework

[Peter Zijlstra]

On Tue, Jun 19, 2018 at 04:21:16PM +0200, Peter Zijlstra wrote:
> 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().

Mark reminded me that per_cpu() does not in fact imply that, but
READ_ONCE(per_cpu()) should work.