Re: [PATCH RFC 09/22] drivers: base: add arch_cpu_is_hotpluggable()

[Shaoqin Huang <shahuang@xxxxxxxxxx>]

On 11/7/23 18:30, Russell King (Oracle) wrote:
> The differences between architecture specific implementations of
> arch_register_cpu() are down to whether the CPU is hotpluggable or not.
> Rather than overriding the weak version of arch_register_cpu(), provide
> a function that can be used to provide this detail instead.
>
> Signed-off-by: Russell King (Oracle) <rmk+kernel@xxxxxxxxxxxxxxx>
Reviewed-by: Shaoqin Huang <shahuang@xxxxxxxxxx>
> ---
>   drivers/base/cpu.c  | 11 ++++++++++-
>   include/linux/cpu.h |  1 +
>   2 files changed, 11 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/base/cpu.c b/drivers/base/cpu.c
> index 58bb86091b34..221ffbeb1c9b 100644
> --- a/drivers/base/cpu.c
> +++ b/drivers/base/cpu.c
> @@ -527,9 +527,18 @@ EXPORT_SYMBOL_GPL(cpu_is_hotpluggable);
>   #ifdef CONFIG_GENERIC_CPU_DEVICES
>   DEFINE_PER_CPU(struct cpu, cpu_devices);
>   
> +bool __weak arch_cpu_is_hotpluggable(int cpu)
> +{
> +	return false;
> +}
> +
>   int __weak arch_register_cpu(int cpu)
>   {
> -	return register_cpu(&per_cpu(cpu_devices, cpu), cpu);
> +	struct cpu *c = &per_cpu(cpu_devices, cpu);
> +
> +	c->hotpluggable = arch_cpu_is_hotpluggable(cpu);
> +
> +	return register_cpu(c, cpu);
>   }
>   
>   #ifdef CONFIG_HOTPLUG_CPU
> diff --git a/include/linux/cpu.h b/include/linux/cpu.h
> index 1e982d63eae8..dcb89c987164 100644
> --- a/include/linux/cpu.h
> +++ b/include/linux/cpu.h
> @@ -80,6 +80,7 @@ extern __printf(4, 5)
>   struct device *cpu_device_create(struct device *parent, void *drvdata,
>   				 const struct attribute_group **groups,
>   				 const char *fmt, ...);
> +extern bool arch_cpu_is_hotpluggable(int cpu);
>   extern int arch_register_cpu(int cpu);
>   extern void arch_unregister_cpu(int cpu);
>   #ifdef CONFIG_HOTPLUG_CPU

--
Shaoqin