kernel/cpu.c:1305:2: error: implicit declaration of function 'cpu_up_down_serialize_trainwrecks'

[kernel test robot <lkp@intel.com>]

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tree:   https://github.com/0day-ci/linux/commits/UPDATE-20210328-050509/Alexey-Klimov/cpu-hotplug-wait-for-cpuset_hotplug_work-to-finish-on-cpu-onlining/20210317-084056
head:   4e665674caba94bc825338d96c58ba0b87317daf
commit: 4e665674caba94bc825338d96c58ba0b87317daf cpu/hotplug: wait for cpuset_hotplug_work to finish on cpu onlining
date:   27 hours ago
config: powerpc-chrp32_defconfig (attached as .config)
compiler: powerpc-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/4e665674caba94bc825338d96c58ba0b87317daf
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review UPDATE-20210328-050509/Alexey-Klimov/cpu-hotplug-wait-for-cpuset_hotplug_work-to-finish-on-cpu-onlining/20210317-084056
        git checkout 4e665674caba94bc825338d96c58ba0b87317daf
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross ARCH=powerpc 

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>

All errors (new ones prefixed by >>):

   kernel/cpu.c: In function '_cpu_up':
>> kernel/cpu.c:1305:2: error: implicit declaration of function 'cpu_up_down_serialize_trainwrecks' [-Werror=implicit-function-declaration]
    1305 |  cpu_up_down_serialize_trainwrecks(tasks_frozen);
         |  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   cc1: some warnings being treated as errors


vim +/cpu_up_down_serialize_trainwrecks +1305 kernel/cpu.c

  1247	
  1248	/* Requires cpu_add_remove_lock to be held */
  1249	static int _cpu_up(unsigned int cpu, int tasks_frozen, enum cpuhp_state target)
  1250	{
  1251		struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
  1252		struct task_struct *idle;
  1253		int ret = 0;
  1254	
  1255		cpus_write_lock();
  1256	
  1257		if (!cpu_present(cpu)) {
  1258			ret = -EINVAL;
  1259			goto out;
  1260		}
  1261	
  1262		/*
  1263		 * The caller of cpu_up() might have raced with another
  1264		 * caller. Nothing to do.
  1265		 */
  1266		if (st->state >= target)
  1267			goto out;
  1268	
  1269		if (st->state == CPUHP_OFFLINE) {
  1270			/* Let it fail before we try to bring the cpu up */
  1271			idle = idle_thread_get(cpu);
  1272			if (IS_ERR(idle)) {
  1273				ret = PTR_ERR(idle);
  1274				goto out;
  1275			}
  1276		}
  1277	
  1278		cpuhp_tasks_frozen = tasks_frozen;
  1279	
  1280		cpuhp_set_state(st, target);
  1281		/*
  1282		 * If the current CPU state is in the range of the AP hotplug thread,
  1283		 * then we need to kick the thread once more.
  1284		 */
  1285		if (st->state > CPUHP_BRINGUP_CPU) {
  1286			ret = cpuhp_kick_ap_work(cpu);
  1287			/*
  1288			 * The AP side has done the error rollback already. Just
  1289			 * return the error code..
  1290			 */
  1291			if (ret)
  1292				goto out;
  1293		}
  1294	
  1295		/*
  1296		 * Try to reach the target state. We max out on the BP at
  1297		 * CPUHP_BRINGUP_CPU. After that the AP hotplug thread is
  1298		 * responsible for bringing it up to the target state.
  1299		 */
  1300		target = min((int)target, CPUHP_BRINGUP_CPU);
  1301		ret = cpuhp_up_callbacks(cpu, st, target);
  1302	out:
  1303		cpus_write_unlock();
  1304		arch_smt_update();
> 1305		cpu_up_down_serialize_trainwrecks(tasks_frozen);
  1306		return ret;
  1307	}
  1308	

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all(a)lists.01.org

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