From: "Rafael J. Wysocki" <rjw@sisk.pl>
To: Mark Lord <lkml@rtr.ca>
Subject: Re: [PATCH] disable non-boot CPUs before poweroff
Date: Fri, 28 Sep 2007 17:05:17 +0200
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       simon.derr@bull.net
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On Friday, 28 September 2007 15:52, Mark Lord wrote:
> 
> 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();

Before sysdev_shutdown(), please.

sysdev_shutdown() may touch things that belong to CPU0.

>  	printk(KERN_EMERG "Power down.\n");
>  	machine_power_off();
>  }

Greetings,
Rafael
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