[kbuild-all] samples/ftrace/ftrace-direct-multi-modify.c:7:6: warning: no previous prototype for function 'my_direct_func1'

tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master head: 9eaa88c7036eda3f6c215f87ca693594cf90559b commit: e1067a07cfbc5a36abad3752fafe4c79e06db1bb ftrace/samples: Add module to test multi direct modify interface date: 9 days ago config: x86_64-randconfig-a001-20211219 (https://download.01.org/0day-ci/archive/20211219/202112190117.RKPcHQjE-lk...) compiler: clang version 14.0.0 (https://github.com/llvm/llvm-project 4c9e31a4814592bbda7153833e46728dc7b21100) 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/torvalds/linux.git/commit... git remote add linus https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git git fetch --no-tags linus master git checkout e1067a07cfbc5a36abad3752fafe4c79e06db1bb # save the config file to linux build tree mkdir build_dir COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=x86_64 SHELL=/bin/bash samples/ftrace/ 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 >>): void my_direct_func1(unsigned long ip) ^ samples/ftrace/ftrace-direct-multi-modify.c:7:1: note: declare 'static' if the function is not intended to be used outside of this translation unit void my_direct_func1(unsigned long ip) ^ static void my_direct_func2(unsigned long ip) ^ samples/ftrace/ftrace-direct-multi-modify.c:12:1: note: declare 'static' if the function is not intended to be used outside of this translation unit void my_direct_func2(unsigned long ip) ^ static 2 warnings generated. vim +/my_direct_func1 +7 samples/ftrace/ftrace-direct-multi-modify.c 6 8 { 9 trace_printk("my direct func1 ip %lx\n", ip); 10 } 11 13 { 14 trace_printk("my direct func2 ip %lx\n", ip); 15 } 16 --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org