[PATCH] Disable CPU hotplug during suspend
The current suspend code has to be run on one CPU, so we use the CPU
hotplug to take the non-boot CPUs offline on SMP machines. However, we
should also make sure that these CPUs will not be enabled by someone else
after we have disabled them.
The functions disable_nonboot_cpus() and enable_nonboot_cpus() are moved to
kernel/cpu.c, because they now refer to some stuff in there that should
better be static. Also it's better if disable_nonboot_cpus() returns an
error instead of panicking if something goes wrong, and
enable_nonboot_cpus() has no reason to panic(), because the CPUs may have
been enabled by the userland before it tries to take them online.
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/kernel/power/user.c b/kernel/power/user.c
index 3f1539f..0ef5e4b 100644
--- a/kernel/power/user.c
+++ b/kernel/power/user.c
@@ -19,6 +19,7 @@
#include <linux/swapops.h>
#include <linux/pm.h>
#include <linux/fs.h>
+#include <linux/cpu.h>
#include <asm/uaccess.h>
@@ -139,12 +140,15 @@
if (data->frozen)
break;
down(&pm_sem);
- disable_nonboot_cpus();
- if (freeze_processes()) {
- thaw_processes();
- enable_nonboot_cpus();
- error = -EBUSY;
+ error = disable_nonboot_cpus();
+ if (!error) {
+ error = freeze_processes();
+ if (error) {
+ thaw_processes();
+ error = -EBUSY;
+ }
}
+ enable_nonboot_cpus();
up(&pm_sem);
if (!error)
data->frozen = 1;
