[ammarfaizi2-block:paulmck/linux-rcu/paronl.2023.02.01a 5/9] arch/x86/kernel/smpboot.c:1251:5: warning: no previous prototype for 'do_cpu_up'

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

tree:   https://github.com/ammarfaizi2/linux-block paulmck/linux-rcu/paronl.2023.02.01a
head:   05792727280c094a8dcd1aa4950a61a2d214ddb8
commit: 9d418800f17cbc141c9ec5772e4d34c4c7b67936 [5/9] x86/smpboot: Split up native_cpu_up into separate phases and document them
config: x86_64-randconfig-a001-20230130 (https://download.01.org/0day-ci/archive/20230202/202302021011.Db4Od62h-lkp@intel.com/config)
compiler: gcc-11 (Debian 11.3.0-8) 11.3.0
reproduce (this is a W=1 build):
        # https://github.com/ammarfaizi2/linux-block/commit/9d418800f17cbc141c9ec5772e4d34c4c7b67936
        git remote add ammarfaizi2-block https://github.com/ammarfaizi2/linux-block
        git fetch --no-tags ammarfaizi2-block paulmck/linux-rcu/paronl.2023.02.01a
        git checkout 9d418800f17cbc141c9ec5772e4d34c4c7b67936
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        make W=1 O=build_dir ARCH=x86_64 olddefconfig
        make W=1 O=build_dir ARCH=x86_64 SHELL=/bin/bash arch/x86/kernel/

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

All warnings (new ones prefixed by >>):

>> arch/x86/kernel/smpboot.c:1251:5: warning: no previous prototype for 'do_cpu_up' [-Wmissing-prototypes]
    1251 | int do_cpu_up(unsigned int cpu, struct task_struct *tidle)
         |     ^~~~~~~~~


vim +/do_cpu_up +1251 arch/x86/kernel/smpboot.c

  1250	
> 1251	int do_cpu_up(unsigned int cpu, struct task_struct *tidle)
  1252	{
  1253		int apicid = apic->cpu_present_to_apicid(cpu);
  1254		int cpu0_nmi_registered = 0;
  1255		int err, ret = 0;
  1256	
  1257		lockdep_assert_irqs_enabled();
  1258	
  1259		pr_debug("++++++++++++++++++++=_---CPU UP  %u\n", cpu);
  1260	
  1261		if (apicid == BAD_APICID ||
  1262		    !physid_isset(apicid, phys_cpu_present_map) ||
  1263		    !apic->apic_id_valid(apicid)) {
  1264			pr_err("%s: bad cpu %d\n", __func__, cpu);
  1265			return -EINVAL;
  1266		}
  1267	
  1268		/*
  1269		 * Already booted CPU?
  1270		 */
  1271		if (cpumask_test_cpu(cpu, cpu_callin_mask)) {
  1272			pr_debug("do_boot_cpu %d Already started\n", cpu);
  1273			return -ENOSYS;
  1274		}
  1275	
  1276		/*
  1277		 * Save current MTRR state in case it was changed since early boot
  1278		 * (e.g. by the ACPI SMI) to initialize new CPUs with MTRRs in sync:
  1279		 */
  1280		mtrr_save_state();
  1281	
  1282		/* x86 CPUs take themselves offline, so delayed offline is OK. */
  1283		err = cpu_check_up_prepare(cpu);
  1284		if (err && err != -EBUSY)
  1285			return err;
  1286	
  1287		/* the FPU context is blank, nobody can own it */
  1288		per_cpu(fpu_fpregs_owner_ctx, cpu) = NULL;
  1289	
  1290		err = common_cpu_up(cpu, tidle);
  1291		if (err)
  1292			return err;
  1293	
  1294		err = do_boot_cpu(apicid, cpu, tidle, &cpu0_nmi_registered);
  1295		if (err) {
  1296			pr_err("do_boot_cpu failed(%d) to wakeup CPU#%u\n", err, cpu);
  1297			ret = -EIO;
  1298			goto unreg_nmi;
  1299		}
  1300	
  1301	unreg_nmi:
  1302		/*
  1303		 * Clean up the nmi handler. Do this after the callin and callout sync
  1304		 * to avoid impact of possible long unregister time.
  1305		 */
  1306		if (cpu0_nmi_registered)
  1307			unregister_nmi_handler(NMI_LOCAL, "wake_cpu0");
  1308	
  1309		return ret;
  1310	}
  1311	

-- 
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