Fix SMP poweroff hangs

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@pobox.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 2 insertions, 0 deletions

diff --git a/kernel/sys.c b/kernel/sys.c
index 1b33b05d346b..8ae2e636eb1b 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -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 @@ void kernel_power_off(void)
         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();