Re: [PATCH 2/3] cpu: add a CPU_DOWN_PREPARE notifier

[Nick Piggin]

Rusty Russell wrote:
> On Wed, 2004-09-08 at 22:52, Nick Piggin wrote:
>
> > 2/3
> >
> > Rusty, can I do this?
> >
> > ______________________________________________________________________
> > Add a CPU_DOWN_PREPARE hotplug CPU notifier. This is needed so we can
> > dettach all sched-domains before a CPU goes down, thus we can build
> > domains from online cpumasks, and not have to check for the possibility
> > of a CPU coming up or going down.
>
>
> And if taking the CPU down fails?  If you need this, you need the
> CPU_DOWN_FAILED as well, unfortunately.  Hence I prefer the "do the
> domain thing while machine is frozen" and sidestep it entirely.

Really? It doesn't need to be run from the stop_machine_run
context at all - it can happily be done while the system is
running.

That said, if you really object to CPU_DOWN_PREPARE and CPU_DOWN_FAILED,
it probably shouldn't be too much work. Should it make the call from
take_cpu_down?
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