Re: [Xen-devel] [PATCH v4 05/11] x86/intel_pstate: relocate the driver register function

["Wang, Wei W" <wei.w.wang@xxxxxxxxx>]

On 24/07/2015 21:36,  Jan Beulich wrote:
> >>> On 25.06.15 at 13:16, <wei.w.wang@xxxxxxxxx> wrote:
> > Register the CPU hotplug notifier when the driver is registered, and
> > move the driver register function to the cpufreq.c.
> 
> At the very least this ought to be merged with the previous patch.
> 
> > --- a/xen/drivers/cpufreq/cpufreq.c
> > +++ b/xen/drivers/cpufreq/cpufreq.c
> > @@ -630,10 +630,18 @@ static struct notifier_block cpu_nfb = {
> >      .notifier_call = cpu_callback
> >  };
> >
> > -static int __init cpufreq_presmp_init(void)
> > +int cpufreq_register_driver(struct cpufreq_driver *driver_data)
> >  {
> > +    if (!driver_data || !driver_data->init ||
> > +        !driver_data->verify || !driver_data->exit ||
> > +        (!driver_data->target == !driver_data->setpolicy))
> > +        return -EINVAL;
> > +
> > +    if (cpufreq_driver)
> > +        return -EBUSY;
> > +
> > +    cpufreq_driver = driver_data;
> > +
> >      register_cpu_notifier(&cpu_nfb);
> >      return 0;
> >  }
> > -presmp_initcall(cpufreq_presmp_init);
> 
> But then the code is left inconsistent: When will the notifier be called for 
> all
> the CPUs that are already up?

Since I will keep the cpufreq_presmp_init() there, 
register_cpu_notifier(&cpu_nfb) will be called in the presmp function there.

Best,
Wei

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