[PATCH] disable non-boot CPUs before poweroff

[Mark Lord <lkml@rtr.ca>]

We need to disable all CPUs other than the boot CPU (usually 0)
before attempting to power-off modern SMP machines.
This seems to fix the hang-on-poweroff issue
that one of my SMP boxes exhibits.  More testing required.

Signed-off-by: Mark Lord <mlord@pobox.com>
---

--- linux/kernel/sys.c.orig	2007-09-13 09:49:11.000000000 -0400
+++ linux/kernel/sys.c	2007-09-28 09:48:54.000000000 -0400
@@ -32,6 +32,7 @@
 #include <linux/getcpu.h>
 #include <linux/task_io_accounting_ops.h>
 #include <linux/seccomp.h>
+#include <linux/cpu.h>
 
 #include <linux/compat.h>
 #include <linux/syscalls.h>
@@ -879,6 +880,7 @@
 	if (pm_power_off_prepare)
 		pm_power_off_prepare();
 	sysdev_shutdown();
+	disable_nonboot_cpus();
 	printk(KERN_EMERG "Power down.\n");
 	machine_power_off();
 }