Hi Florian, I love your patch! Yet something to improve: [auto build test ERROR on next-20220310] [cannot apply to nf-next/master nf/master linus/master v5.17-rc7 v5.17-rc6 v5.17-rc5 v5.17-rc7] [If your patch is applied to the wrong git tree, kindly drop us a note. And when submitting patch, we suggest to use '--base' as documented in https://git-scm.com/docs/git-format-patch] url: https://github.com/0day-ci/linux/commits/Florian-Westphal/netfilter-nf_tables-add-stubs-for-readonly-expressions/20220311-185613 base: 71941773e143369a73c9c4a3b62fbb60736a1182 config: arm64-allmodconfig (https://download.01.org/0day-ci/archive/20220312/202203120618.2FZ2VXaE-lkp@xxxxxxxxx/config) compiler: clang version 15.0.0 (https://github.com/llvm/llvm-project 276ca87382b8f16a65bddac700202924228982f6) 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 # install arm64 cross compiling tool for clang build # apt-get install binutils-aarch64-linux-gnu # https://github.com/0day-ci/linux/commit/a0cb27794354ccba36b882731b93fdda090f2003 git remote add linux-review https://github.com/0day-ci/linux git fetch --no-tags linux-review Florian-Westphal/netfilter-nf_tables-add-stubs-for-readonly-expressions/20220311-185613 git checkout a0cb27794354ccba36b882731b93fdda090f2003 # 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=arm64 SHELL=/bin/bash drivers/gpu/drm/panel/ net/netfilter/ If you fix the issue, kindly add following tag as appropriate Reported-by: kernel test robot <lkp@xxxxxxxxx> All errors (new ones prefixed by >>): >> net/netfilter/nft_cmp.c:363:13: error: use of undeclared identifier 'nft_cmp_reduce'; did you mean 'nft_cmp_dump'? .reduce = nft_cmp_reduce, ^~~~~~~~~~~~~~ nft_cmp_dump net/netfilter/nft_cmp.c:99:12: note: 'nft_cmp_dump' declared here static int nft_cmp_dump(struct sk_buff *skb, const struct nft_expr *expr) ^ >> net/netfilter/nft_cmp.c:363:13: error: incompatible function pointer types initializing 'bool (*)(struct nft_regs_track *, const struct nft_expr *)' (aka '_Bool (*)(struct nft_regs_track *, const struct nft_expr *)') with an expression of type 'int (struct sk_buff *, const struct nft_expr *)' [-Werror,-Wincompatible-function-pointer-types] .reduce = nft_cmp_reduce, ^~~~~~~~~~~~~~ 2 errors generated. vim +363 net/netfilter/nft_cmp.c 354 355 356 const struct nft_expr_ops nft_cmp16_fast_ops = { 357 .type = &nft_cmp_type, 358 .size = NFT_EXPR_SIZE(sizeof(struct nft_cmp16_fast_expr)), 359 .eval = NULL, /* inlined */ 360 .init = nft_cmp16_fast_init, 361 .dump = nft_cmp16_fast_dump, 362 .offload = nft_cmp16_fast_offload, > 363 .reduce = nft_cmp_reduce, 364 }; 365 --- 0-DAY CI Kernel Test Service https://lists.01.org/hyperkitty/list/kbuild-all@xxxxxxxxxxxx