Re: [PATCH v2] cpu/hotplug: Set st->cpu earlier

[Vincent Donnefort]

On 22/03/2022 15:31, Thomas Gleixner wrote:
> On Wed, Mar 16 2022 at 15:36, Steven Price wrote:
> > Setting the 'cpu' member of struct cpuhp_cpu_state in cpuhp_create() is
> > too late as other callbacks can be made before that point.
>
> What?
>
>          CPUHP_OFFLINE = 0,
>          CPUHP_CREATE_THREADS,
>
> The create threads callback is the very first callback which is invoked
> for a to be plugged CPU on the control CPU. So which earlier callback
> can be invoked and fail?
>
> Thanks,
>
>          tglx


CPUHP_CREATE_THREADS itself can fail, before st->cpu is set. Also, that 
value is used outside of the callbacks (cpuhp_set_state() in _cpu_up()).

But indeed this description could be refined a bit.