Re: sched domains bringup race?

[Nick Piggin]

Nick Piggin wrote:
> Dave Hansen wrote:
>
> > On Thu, 2004-07-15 at 20:03, Nick Piggin wrote:
> >
> > > It shouldn't because sched_init sets up dummy domains for
> > > all runqueues.
> > >
> > > Obviously something is going wrong somewhere though.
> >
> >
> >
> > Hmmm, but there still might be some concurrency problems, right?  There
> > isn't any locking while the setup is being done, so are all of the
> > intermediate initialization states valid?  Or, could one of the CPUs be
> > catching the init code in the middle of an operation?
>
> cpu_attach_domain is supposed to be able to do the switchover
> without any races.

Although the sched_domain_debug is definitely racy. It should really
be locking each runqueue before traversing its domains. Just undef
SCHED_DOMAIN_DEBUG to be sure...
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