Re: [Xen-devel] [PATCH v2 5/9] x86/intel_pstate: relocate the driver register/unregister function

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 13.05.16 at 09:50, <wei.w.wang@xxxxxxxxx> wrote:
> Register/unregister the CPU hotplug notifier when the driver is
> registered, and move the driver register/unregister function to
> the cpufreq.c.

Without saying why I'm afraid I don't even see much reason to
review this in any detail.

> --- a/xen/drivers/cpufreq/cpufreq.c
> +++ b/xen/drivers/cpufreq/cpufreq.c
> @@ -630,12 +630,31 @@ 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)
>  {
> -    void *cpu = (void *)(long)smp_processor_id();
> -    cpu_callback(&cpu_nfb, CPU_ONLINE, cpu);

Why is this being removed without replacement?

> +    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);
>  
> +int cpufreq_unregister_driver(struct cpufreq_driver *driver)
> +{
> +    if (!cpufreq_driver || (driver != cpufreq_driver))
> +        return -EINVAL;
> +
> +    cpufreq_driver = NULL;
> +
> +    unregister_cpu_notifier(&cpu_nfb);
> +
> +    return 0;
> +}

This function is dead (and perhaps just like unregister_cpu_notifier()
not even needed without loadable modules).

Jan


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