tree: https://github.com/0day-ci/linux/commits/UPDATE-20200520-041207/Zhou-Yanj... head: 4fff52cd90c9406079cc6395408c8a56e7e4312d commit: ad29da9806feb410651e7428a8ac27ab8f9104ff [1/6] MIPS: JZ4780: Introduce SMP support. config: mips-randconfig-r023-20200520 (attached as .config) compiler: clang version 11.0.0 (https://github.com/llvm/llvm-project e6658079aca6d971b4e9d7137a3a2ecbc9c34aec) reproduce: wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross chmod +x ~/bin/make.cross # install mips cross compiling tool for clang build # apt-get install binutils-mips-linux-gnu git checkout ad29da9806feb410651e7428a8ac27ab8f9104ff # save the attached .config to linux build tree COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=mips If you fix the issue, kindly add following tag as appropriate Reported-by: kbuild test robot <lkp(a)intel.com&gt; All warnings (new ones prefixed by >>, old ones prefixed by <<): void jz4780_smp_wait_irqoff(void) ^ arch/mips/kernel/idle.c:97:1: note: declare 'static' if the function is not intended to be used outside of this translation unit void jz4780_smp_wait_irqoff(void) ^ static arch/mips/kernel/idle.c:155:13: warning: no previous prototype for function 'check_wait' [-Wmissing-prototypes] void __init check_wait(void) ^ arch/mips/kernel/idle.c:155:1: note: declare 'static' if the function is not intended to be used outside of this translation unit void __init check_wait(void) ^ static 2 warnings generated. vim +/jz4780_smp_wait_irqoff +97 arch/mips/kernel/idle.c 90 91 /* 92 * The Ingenic jz4780 SMP variant has to write back dirty cache lines before 93 * executing wait. The CPU & cache clock will be gated until we return from 94 * the wait, and if another core attempts to access data from our data cache 95 * during this time then it will lock up. 96 */ 98 { 99 unsigned long pending = read_c0_cause() & read_c0_status() & CAUSEF_IP; 100 101 /* 102 * Going to idle has a significant overhead due to the cache flush so 103 * try to avoid it if we'll immediately be woken again due to an IRQ. 104 */ 105 if (!need_resched() && !pending) { 106 r4k_blast_dcache(); 107 108 __asm__( 109 " .set push \n" 110 " .set mips3 \n" 111 " sync \n" 112 " wait \n" 113 " .set pop \n"); 114 } 115 116 local_irq_enable(); 117 } 118 --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org