[PATCH] (repost) Fix SMP poweroff hangs

[Mark Lord]

Rafael J. Wysocki wrote:
> ..
> > @@ -879,6 +880,7 @@
> >  	if (pm_power_off_prepare)
> >  		pm_power_off_prepare();
> >  	sysdev_shutdown();
> > +	disable_nonboot_cpus();
>
> Before sysdev_shutdown(), please.
>
> sysdev_shutdown() may touch things that belong to CPU0.

Thanks.  Here is the revised patch.

* * *

We need to disable all CPUs other than the boot CPU (usually 0)
before attempting to power-off modern SMP machines.
This fixes the hang-on-poweroff issue on my MythTV SMP box,
and also on Thomas Gleixner's new toybox.

Signed-off-by: Mark Lord <mlord@xxxxxxxxx>
Acked-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
---

--- linux/kernel/sys.c.orig	2007-09-13 09:49:11.000000000 -0400
+++ linux/kernel/sys.c	2007-09-28 15:48:54.000000000 -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>
@@ -878,6 +879,7 @@
	kernel_shutdown_prepare(SYSTEM_POWER_OFF);
	if (pm_power_off_prepare)
		pm_power_off_prepare();
+	disable_nonboot_cpus();
	sysdev_shutdown();
	printk(KERN_EMERG "Power down.\n");
	machine_power_off();
-
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