Re: [PATCHv10 03/18] cpu/hotplug: Add support for declaring CPU offlining not supported

[Kirill A. Shutemov]

On Thu, Apr 18, 2024 at 04:37:09PM +0200, Borislav Petkov wrote:
> On Tue, Apr 09, 2024 at 02:29:55PM +0300, Kirill A. Shutemov wrote:
> > +/* Declare CPU offlining not supported */
> > +void cpu_hotplug_disable_offlining(void)
> > +{
> > +	cpu_maps_update_begin();
> 
> "/*
>  * The following two APIs (cpu_maps_update_begin/done) must be used when
>  * attempting to serialize the updates to cpu_online_mask & cpu_present_mask.
>  */
> void cpu_maps_update_begin(void)
> ..."
> 
> > +	cpu_hotplug_offline_disabled = true;
> 
> but this doesn't do that here.
> 
> Are we doing a one-off here for that variable or what?

Yes, it is one-off. I guess we could use READ_ONCE()/WRITE_ONCE() to
access the variable with the same result. I am not sure why it would be
better.

-- 
  Kiryl Shutsemau / Kirill A. Shutemov