Hi Martin, I love your patch! Yet something to improve: [auto build test ERROR on bpf-next/master] url: https://github.com/0day-ci/linux/commits/Martin-KaFai-Lau/Support-calling... base: https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next.git master config: parisc-defconfig (attached as .config) compiler: hppa-linux-gcc (GCC) 9.3.0 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://github.com/0day-ci/linux/commit/5839e49467b4593db0b16c1343cf9d9d6... git remote add linux-review https://github.com/0day-ci/linux git fetch --no-tags linux-review Martin-KaFai-Lau/Support-calling-kernel-function/20210316-091639 git checkout 5839e49467b4593db0b16c1343cf9d9d60cc6dcd # save the attached .config to linux build tree COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross ARCH=parisc If you fix the issue, kindly add following tag as appropriate Reported-by: kernel test robot <lkp(a)intel.com&gt; All errors (new ones prefixed by >>): hppa-linux-ld: net/core/filter.o: in function `tc_cls_check_kern_func_call': --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org