tree: https://git.kernel.org/pub/scm/linux/kernel/git/mcgrof/linux-next.git 20211116-sysctl-cleanups-v3 head: 06113f1d9a2d0669964adfa2e0128bd50e56b621 commit: 72daf12fc8290df22f4479f912a74c73a6a2fe38 [11/20] macintosh/mac_hid.c: use new sysctl subdir helper register_sysctl_subdir() config: i386-randconfig-a003-20211116 (attached as .config) compiler: clang version 14.0.0 (https://github.com/llvm/llvm-project 4c2cf3a314d9131b1b288e7c8ab0c75ac1b2be1d) 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/mcgrof/linux-next.git/com... git remote add mcgrof-next https://git.kernel.org/pub/scm/linux/kernel/git/mcgrof/linux-next.git git fetch --no-tags mcgrof-next 20211116-sysctl-cleanups-v3 git checkout 72daf12fc8290df22f4479f912a74c73a6a2fe38 # save the attached .config to linux build tree COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 ARCH=i386 If you fix the issue, kindly add following tag as appropriate Reported-by: kernel test robot <lkp(a)intel.com&gt; All warnings (new ones prefixed by >>): drivers/macintosh/mac_hid.c:246:26: error: implicit declaration of function 'register_sysctl_subdir' [-Werror,-Wimplicit-function-declaration] mac_hid_sysctl_header = register_sysctl_subdir("dev", "mac_hid", ^ mac_hid_sysctl_header = register_sysctl_subdir("dev", "mac_hid", ^ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1 warning and 1 error generated. vim +246 drivers/macintosh/mac_hid.c 243 244 static int __init mac_hid_init(void) 245 { 247 mac_hid_files); 248 if (!mac_hid_sysctl_header) 249 return -ENOMEM; 250 251 return 0; 252 } 253 module_init(mac_hid_init); 254 --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org