tree: https://github.com/zen-kernel/zen-kernel 5.13/futex2 head: 67f7da92d1cb45a815c7046f8719942a728216d0 commit: 16c6deba3504c19acf820b765762adf60a53d9d2 [4/5] futex2: Add sysfs entry for syscall numbers config: arc-buildonly-randconfig-r006-20210709 (attached as .config) compiler: arc-elf-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/zen-kernel/zen-kernel/commit/16c6deba3504c19acf820b765... git remote add zen-kernel-zen-kernel https://github.com/zen-kernel/zen-kernel git fetch --no-tags zen-kernel-zen-kernel 5.13/futex2 git checkout 16c6deba3504c19acf820b765762adf60a53d9d2 # save the attached .config to linux build tree mkdir build_dir COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross O=build_dir ARCH=arc SHELL=/bin/bash 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 >>): In file included from arch/arc/include/uapi/asm/unistd.h:31, from include/uapi/linux/unistd.h:8, from include/linux/syscalls.h:83, from kernel/futex2.c:8: include/uapi/asm-generic/unistd.h:879: warning: "__NR_futex_wait" redefined 879 | #define __NR_futex_wait 449 | include/uapi/asm-generic/unistd.h:875: note: this is the location of the previous definition 875 | #define __NR_futex_wait 447 | kernel/futex2.c: In function 'waitv_show': 450 | return sprintf(buf, "%u\n", __NR_futex_waitv); | ^~~~~~~~~~~~~~~~ | sys_futex_waitv kernel/futex2.c:450:30: note: each undeclared identifier is reported only once for each function it appears in kernel/futex2.c:452:1: error: control reaches end of non-void function [-Werror=return-type] 452 | } | ^ In file included from include/linux/perf_event.h:25, from include/linux/trace_events.h:10, from include/trace/syscall.h:7, from include/linux/syscalls.h:87, from kernel/futex2.c:8: At top level: arch/arc/include/asm/perf_event.h:126:23: warning: 'arc_pmu_cache_map' defined but not used [-Wunused-const-variable=] 126 | static const unsigned arc_pmu_cache_map[C(MAX)][C(OP_MAX)][C(RESULT_MAX)] = { | ^~~~~~~~~~~~~~~~~ arch/arc/include/asm/perf_event.h:91:27: warning: 'arc_pmu_ev_hw_map' defined but not used [-Wunused-const-variable=] 91 | static const char * const arc_pmu_ev_hw_map[] = { | ^~~~~~~~~~~~~~~~~ cc1: some warnings being treated as errors vim +450 kernel/futex2.c 446 447 static ssize_t waitv_show(struct kobject *kobj, struct kobj_attribute *attr, 448 char *buf) 449 { 451 --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org