On Wed, Feb 04, 2015 at 01:00:18PM +0000, Russell King - ARM Linux wrote:
> On Wed, Feb 04, 2015 at 12:39:07PM +0100, Krzysztof Kozlowski wrote:
> > +Cc some ARM people
>
> I wish that people would CC this list with problems seen on ARM. I'm
> minded to just ignore this message because of this in the hope that by
> doing so, people will learn something...
>
> > > Another thing I could do would be to have an arch-specific Kconfig
> > > variable that made ARM responsible for informing RCU that the CPU
> > > was departing, which would allow a call to as follows to be placed
> > > immediately after the complete():
> > >
> > > rcu_cpu_notify(NULL, CPU_DYING_IDLE, (void *)(long)smp_processor_id());
> > >
> > > Note: This absolutely requires that the rcu_cpu_notify() -always-
> > > be allowed to execute!!! This will not work if there is -any- possibility
> > > of __cpu_die() powering off the outgoing CPU before the call to
> > > rcu_cpu_notify() returns.
>
> Exactly, so that's not going to be possible. The completion at that
> point marks the point at which power _could_ be removed from the CPU
> going down.
OK, sounds like a polling loop is required.
Thanx, Paul
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