Re: [PATCH v5 UPDATEDv3 3/3] CPU hotplug, smp: Flush any pending IPI callbacks before CPU offline

From: Peter Zijlstra
Date: Tue May 20 2014 - 06:25:57 EST


On Tue, May 20, 2014 at 03:39:59PM +0530, Srivatsa S. Bhat wrote:
> > The multi_cpu_stop() path isn't exclusive to hotplug, so your changelog
> > is wrong or the patch is.
> >
>
> Yes, I know that multi_cpu_stop() isn't exclusive to hotplug. That's why
> I have explicitly referred to CPU hotplug in the comment as well as the
> changelog.
>
> But I totally agree that code-wise this is not the best way to do it since
> this affects (although harmlessly) usecases other than hotplug as well.
>
> Do you have any other suggestions?

How about making a kernel/smp.c hotplug notifier and stuffing it in the
CPU_DYING list? That's typically after we've already torn down the
interrupts for that cpu, so no chance of any new ones coming in.

Or is that too late?
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