This reverts commit 
7c5c92ed56d932b2c19c3f8aea86369509407d33.
Although this did fix the bug it was aimed at, it also broke secondary
startup on platforms that use give/take_timebase(). Unfortunately we
didn't detect that while it was in next.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
        smp_store_cpu_info(cpu);
        set_dec(tb_ticks_per_jiffy);
        preempt_disable();
+       cpu_callin_map[cpu] = 1;
 
        if (smp_ops->setup_cpu)
                smp_ops->setup_cpu(cpu);
        notify_cpu_starting(cpu);
        set_cpu_online(cpu, true);
 
-       /*
-        * CPU must be marked active and online before we signal back to the
-        * master, because the scheduler needs to see the cpu_online and
-        * cpu_active bits set.
-        */
-       smp_wmb();
-       cpu_callin_map[cpu] = 1;
-
        local_irq_enable();
 
        cpu_startup_entry(CPUHP_ONLINE);