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SubjectRe: [PATCH v4 3/3] powerpc/powernv: Introduce sysfs control for fastsleep workaround behavior

> A point that bothers me here is if we can potentially race with cpu
> hotplug ? If cpuX and its siblings are offline and it was interrupted to
> come online:
> cpuX cpuY
> Interrupted to come online
> Undo workaround
> Nop the fastsleep_workaround_exit path
> IPI online cores: apply workaround once
> Set yourself in the online mask
> Nop the fastsleep_workaround_entry path
> This results in cpuX undoing the workaround on its core, never to set it
> back again.
> So should we protect the region between the beginning and end of
> patching instructions with get_online_cpus() and put_online_cpus() ?

Nice catch. I had missed this. Sending out a patch correcting this.


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