Re: [PATCH] disable non-boot CPUs before poweroff

From: Rafael J. Wysocki
Date: Fri Sep 28 2007 - 10:51:04 EST


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@xxxxxxxxx>
> ---
>
> --- 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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