[PATCH] ppc64: Fix cpu_up race

Patch below fixes a cpu_up race in PPC64.
Signed-off-by: Srivatsa Vaddagiri <vatsa@in.ibm.com>
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

arch/ppc64/kernel/smp.c

@@ -935,7 +935,11 @@ int __devinit __cpu_up(unsigned int cpu)
 
 	if (smp_ops->give_timebase)
 		smp_ops->give_timebase();
-	cpu_set(cpu, cpu_online_map);
+
+	/* Wait until cpu puts itself in the online map */
+	while (!cpu_online(cpu))
+		cpu_relax();
+
 	return 0;
 }
 
@@ -971,6 +975,10 @@ int __devinit start_secondary(void *unused)
 #endif
 #endif
 
+	spin_lock(&call_lock);
+	cpu_set(cpu, cpu_online_map);
+	spin_unlock(&call_lock);
+
 	local_irq_enable();
 
 	return cpu_idle(NULL);