tree: https://git.kernel.org/pub/scm/linux/kernel/git/arnd/playground.git headers-clean-test head: a25b75e508f3199f82d682ff1c5d6968d3286581 commit: 7cb3907a92dcc34da3c9242d72ca7ce2a2313817 [21/30] fixup config: arc-defconfig (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 git checkout 7cb3907a92dcc34da3c9242d72ca7ce2a2313817 # save the attached .config to linux build tree COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross ARCH=arc If you fix the issue, kindly add following tag as appropriate Reported-by: kbuild test robot All errors (new ones prefixed by >>, old ones prefixed by <<): In file included from arch/arc/kernel/asm-offsets.c:6: include/linux/sched.h: In function 'spin_needbreak': include/linux/sched.h:1862:9: error: implicit declaration of function 'spin_is_contended' [-Werror=implicit-function-declaration] 1862 | return spin_is_contended(lock); | ^~~~~~~~~~~~~~~~~ In file included from include/linux/mmzone.h:8, from include/linux/mm.h:13, from arch/arc/kernel/asm-offsets.c:7: include/linux/spinlock.h: At top level: >> include/linux/spinlock.h:449:28: error: static declaration of 'spin_is_contended' follows non-static declaration 449 | static __always_inline int spin_is_contended(spinlock_t *lock) | ^~~~~~~~~~~~~~~~~ In file included from arch/arc/kernel/asm-offsets.c:6: include/linux/sched.h:1862:9: note: previous implicit declaration of 'spin_is_contended' was here 1862 | return spin_is_contended(lock); | ^~~~~~~~~~~~~~~~~ cc1: some warnings being treated as errors make[2]: *** [scripts/Makefile.build:110: arch/arc/kernel/asm-offsets.s] Error 1 make[2]: Target '__build' not remade because of errors. make[1]: *** [Makefile:1177: prepare0] Error 2 make[1]: Target 'prepare' not remade because of errors. make: *** [Makefile:185: __sub-make] Error 2 vim +/spin_is_contended +449 include/linux/spinlock.h c2f21ce2e31286 Thomas Gleixner 2009-12-02 448 3490565b633c70 Denys Vlasenko 2015-07-13 @449 static __always_inline int spin_is_contended(spinlock_t *lock) c2f21ce2e31286 Thomas Gleixner 2009-12-02 450 { c2f21ce2e31286 Thomas Gleixner 2009-12-02 451 return raw_spin_is_contended(&lock->rlock); c2f21ce2e31286 Thomas Gleixner 2009-12-02 452 } c2f21ce2e31286 Thomas Gleixner 2009-12-02 453 :::::: The code at line 449 was first introduced by commit :::::: 3490565b633c705d2fb1f6ede51228952664663d locking/spinlocks: Force inlining of spinlock ops :::::: TO: Denys Vlasenko :::::: CC: Ingo Molnar --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all(a)lists.01.org