I tried below code base.

for (i=0; i<4; i++) {
    pr_err ("%s: checking online cpus : %d ", __func__, i);
    if (cpu_online(i))
      continue;
    pr_err("Onlining CPU%d\n", i);
    if (cpu_up(i)) {
      pr_err("Onlining CPU%d failed\n", i);
    } else
        pr_err("Onlining CPU%d usng smp_call \n", i);
}