RE: [PATCH v9 12/12] x86, topology: Debug CPU00 hotplug

[Yu, Fenghua]

> > +#ifdef CONFIG_DEBUG_HOTPLUG_CPU0
 > +	case PM_RESTORE_PREPARE:
> > +		/*
> > +		 * When system resumes from hibernation, online CPU0
> because
> > +		 * 1. it's required for resume and
> > +		 * 2. the CPU was online before hibernation
> > +		 */
> > +		if (!cpu_online(0))
> > +			_debug_hotplug_cpu(0, 1);
> 
> This won't work. CPU hotplug is disabled by cpu_hotplug_pm_callback()
> during
> PM_HIBERNATION_PREPARE and is enabled back only during
> PM_POST_HIBERNATION.
> 
> So calls to cpu_up() or cpu_down() will fail in the meantime.

The code works just fine.

You are talking about hibernation/suspend phase. This piece of
code is all about restore phase. Of course you can call cpu_up()
and cpu_down() during restore phase.

So there is no problem here.

Thanks.

-Fenghua

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