Re: [patch] KVM, hotplug: export register_cpu_notifier

[Avi Kivity <avi@qumranet.com>]

Ingo Molnar wrote:
> Subject: [patch] KVM, hotplug: export register_cpu_notifier
> From: Ingo Molnar <mingo@elte.hu>
>
> KVM-trunk uses register_cpu_notifier() but it's a module and we only 
> export this if CONFIG_HOTPLUG_CPU. Export it otherwise too.
>
> Signed-off-by: Ingo Molnar <mingo@elte.hu>
> ---
>  kernel/cpu.c |    4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> Index: linux/kernel/cpu.c
> ===================================================================
> --- linux.orig/kernel/cpu.c
> +++ linux/kernel/cpu.c
> @@ -75,10 +75,10 @@ int __cpuinit register_cpu_notifier(stru
>  	return ret;
>  }
>  
> -#ifdef CONFIG_HOTPLUG_CPU
> -
>  EXPORT_SYMBOL(register_cpu_notifier);
>  
> +#ifdef CONFIG_HOTPLUG_CPU
> +
>  void unregister_cpu_notifier(struct notifier_block *nb)
>  {
>  	mutex_lock(&cpu_add_remove_lock);
>   

This is broken: register_cpu_notifier() is __cpuinit, which means it 
disappears at module time if !CONFIG_CPU_HOTPLUG.

I submitted a hackaround to Andrew some time ago with the suspend patchset.

-- 
Do not meddle in the internals of kernels, for they are subtle and quick to panic.