Re: [patch 2/2] cpu hotplug notifier for updating sched domains

From: Rusty Russell
Date: Thu Sep 09 2004 - 05:24:18 EST


On Wed, 2004-09-08 at 12:19, Nick Piggin wrote:
> Nathan Lynch wrote:
> >Well, we have to "lie" to arch_init_sched_domains a little bit when
> >bringing a cpu online, by setting the soon-to-be-online cpu's bit in the
> >argument mask. So I think the first patch is still necessary.

I'm still a little surprised that you don't change the domains while the
machine is frozen (ie in take_cpu_down()). This should avoid any races,
since noone can be looking at the domains at this time.

> Do you have a theoretical race here? Can we hotplug a CPU before the notifier
> is registered? (I know we *can't* because it is still earlyish boot).

No, init has so many serial assumptions that this is the least of our
worries.

Rusty.
--
Anyone who quotes me in their signature is an idiot -- Rusty Russell

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