Hi "Björn, I love your patch! Perhaps something to improve: [auto build test WARNING on 7b1e385c9a488de9291eaaa412146d3972e9dec5] url: https://github.com/0day-ci/linux/commits/Bj-rn-T-pel/Optimize-bpf_redirec... base: 7b1e385c9a488de9291eaaa412146d3972e9dec5 config: nds32-randconfig-r006-20210219 (attached as .config) compiler: nds32le-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/e784328ffb3b588155aeee02ff6a96b4a... git remote add linux-review https://github.com/0day-ci/linux git fetch --no-tags linux-review Bj-rn-T-pel/Optimize-bpf_redirect_map-xdp_do_redirect/20210219-230349 git checkout e784328ffb3b588155aeee02ff6a96b4a6b7cf20 # save the attached .config to linux build tree COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross ARCH=nds32 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 >>): In file included from include/linux/bpf-cgroup.h:5, from include/linux/cgroup-defs.h:22, from include/linux/cgroup.h:28, from include/linux/hugetlb.h:9, from kernel/events/core.c:31: 1629 | static inline int cpu_map_enqueue(struct bpf_cpu_map_entry *rcpu, | ^~~~~~~~~~~~~~~~~ kernel/events/core.c:6539:6: warning: no previous prototype for 'perf_pmu_snapshot_aux' [-Wmissing-prototypes] 6539 | long perf_pmu_snapshot_aux(struct perf_buffer *rb, | ^~~~~~~~~~~~~~~~~~~~~ -- In file included from include/linux/bpf-cgroup.h:5, from include/linux/cgroup-defs.h:22, from include/linux/cgroup.h:28, from include/linux/perf_event.h:57, from kernel/events/ring_buffer.c:11: 1629 | static inline int cpu_map_enqueue(struct bpf_cpu_map_entry *rcpu, | ^~~~~~~~~~~~~~~~~ vim +1629 include/linux/bpf.h 9c270af37bb62e Jesper Dangaard Brouer 2017-10-16 1628 9c270af37bb62e Jesper Dangaard Brouer 2017-10-16 @1629 static inline int cpu_map_enqueue(struct bpf_cpu_map_entry *rcpu, 9c270af37bb62e Jesper Dangaard Brouer 2017-10-16 1630 struct xdp_buff *xdp, 9c270af37bb62e Jesper Dangaard Brouer 2017-10-16 1631 struct net_device *dev_rx) 9c270af37bb62e Jesper Dangaard Brouer 2017-10-16 1632 { 9c270af37bb62e Jesper Dangaard Brouer 2017-10-16 1633 return 0; 9c270af37bb62e Jesper Dangaard Brouer 2017-10-16 1634 } 040ee69226f8a9 Al Viro 2017-12-02 1635 --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org