[morse:virtual_cpu_hotplug/rfc/v1 20/32] drivers/base/cpu.c:504:2: error: implicit declaration of function 'unregister_cpu' is invalid in C99

[kernel test robot <lkp@intel.com>]

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/morse/linux.git virtual_cpu_hotplug/rfc/v1
head:   81295db7555df74bd02dab0b7e87b512d3a3de34
commit: 9048fbcbea6dd1dfa42a3b9409695ff9199a417d [20/32] drivers: base: Implement weak arch_unregister_cpu()
config: x86_64-randconfig-a001 (https://download.01.org/0day-ci/archive/20230205/202302050505.vWGB6FVR-lkp@intel.com/config)
compiler: clang version 14.0.6 (https://github.com/llvm/llvm-project f28c006a5895fc0e329fe15fead81e37457cb1d1)
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # https://git.kernel.org/pub/scm/linux/kernel/git/morse/linux.git/commit/?id=9048fbcbea6dd1dfa42a3b9409695ff9199a417d
        git remote add morse https://git.kernel.org/pub/scm/linux/kernel/git/morse/linux.git
        git fetch --no-tags morse virtual_cpu_hotplug/rfc/v1
        git checkout 9048fbcbea6dd1dfa42a3b9409695ff9199a417d
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=x86_64 olddefconfig
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=x86_64 SHELL=/bin/bash

If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <lkp@intel.com>

All errors (new ones prefixed by >>):

>> drivers/base/cpu.c:504:2: error: implicit declaration of function 'unregister_cpu' is invalid in C99 [-Werror,-Wimplicit-function-declaration]
           unregister_cpu(&per_cpu(cpu_devices, num));
           ^
   drivers/base/cpu.c:504:2: note: did you mean 'register_cpu'?
   drivers/base/cpu.c:359:5: note: 'register_cpu' declared here
   int register_cpu(struct cpu *cpu, int num)
       ^
   1 error generated.

Kconfig warnings: (for reference only)
   WARNING: unmet direct dependencies detected for ACPI_HOTPLUG_PRESENT_CPU
   Depends on [n]: ACPI [=y] && ACPI_PROCESSOR [=y] && HOTPLUG_CPU [=n]
   Selected by [y]:
   - X86 [=y] && ACPI [=y]


vim +/unregister_cpu +504 drivers/base/cpu.c

   501	
   502	void __weak arch_unregister_cpu(int num)
   503	{
 > 504		unregister_cpu(&per_cpu(cpu_devices, num));
   505	}
   506	#endif
   507	

-- 
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https://github.com/intel/lkp-tests