Re: [PATCH for-next/vcpu-hotplug] arm64: Kconfig: Fix dependencies to enable ACPI_HOTPLUG_CPU

[Jonathan Cameron <Jonathan.Cameron@Huawei.com>]

On Mon,  1 Jul 2024 10:11:32 +1000
Gavin Shan <gshan@redhat.com> wrote:

> Both ACPI_PROCESSOR and HOTPLUG_CPU are needed by ACPI_HOTPLUG_CPU.
> Otherwise, we can have compiling error with the following configurations.
> 
>   CONFIG_HOTPLUG_CPU=n
>   CONFIG_ACPI_PROCESSOR=y
>   CONFIG_ACPI_HOTPLUG_CPU=y
> 
>   arch/arm64/kernel/smp.c: In function ‘arch_unregister_cpu’:
>   arch/arm64/kernel/smp.c:563:9: error: implicit declaration of  \
>   function ‘unregister_cpu’; did you mean ‘register_cpu’?        \
>   [-Werror=implicit-function-declaration]
>   563 |         unregister_cpu(c);
>       |         ^~~~~~~~~~~~~~
>       |         register_cpu
> 
> Fix it by enabling ACPI_HOTPLUG_CPU when both ACPI_PROCESSOR and
> HOTPLUG_CPU are enabled, consistent with other architectures like
> x86 and loongarch.
> 
> Fixes: 9d0873892f4d ("arm64: Kconfig: Enable hotplug CPU on arm64 if ACPI_PROCESSOR is enabled.")
> Reported-by: kernel test robot <lkp@intel.com>
> Closes: https://lore.kernel.org/oe-kbuild-all/202406300437.XnuW0n34-lkp@intel.com/
> Signed-off-by: Gavin Shan <gshan@redhat.com>

Thanks for the quick analysis and patch!

Acked-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

> ---
>  arch/arm64/Kconfig | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
> index e8f2ef2312db..ff17c5705324 100644
> --- a/arch/arm64/Kconfig
> +++ b/arch/arm64/Kconfig
> @@ -5,7 +5,7 @@ config ARM64
>  	select ACPI_CCA_REQUIRED if ACPI
>  	select ACPI_GENERIC_GSI if ACPI
>  	select ACPI_GTDT if ACPI
> -	select ACPI_HOTPLUG_CPU if ACPI_PROCESSOR
> +	select ACPI_HOTPLUG_CPU if ACPI_PROCESSOR && HOTPLUG_CPU
>  	select ACPI_IORT if ACPI
>  	select ACPI_REDUCED_HARDWARE_ONLY if ACPI
>  	select ACPI_MCFG if (ACPI && PCI)