[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>
This commit is contained in:
Rafael J. Wysocki 2006-09-25 23:32:48 -07:00 committed by Linus Torvalds
parent e8eff5ac29
commit e3920fb42c
8 changed files with 146 additions and 105 deletions

View File

@ -89,4 +89,12 @@ int cpu_down(unsigned int cpu);
static inline int cpu_is_offline(int cpu) { return 0; }
#endif
#ifdef CONFIG_SUSPEND_SMP
extern int disable_nonboot_cpus(void);
extern void enable_nonboot_cpus(void);
#else
static inline int disable_nonboot_cpus(void) { return 0; }
static inline void enable_nonboot_cpus(void) {}
#endif
#endif /* _LINUX_CPU_H_ */

View File

@ -57,14 +57,6 @@ static inline int software_suspend(void)
}
#endif /* CONFIG_PM */
#ifdef CONFIG_SUSPEND_SMP
extern void disable_nonboot_cpus(void);
extern void enable_nonboot_cpus(void);
#else
static inline void disable_nonboot_cpus(void) {}
static inline void enable_nonboot_cpus(void) {}
#endif
void save_processor_state(void);
void restore_processor_state(void);
struct saved_context;

View File

@ -21,6 +21,11 @@ static DEFINE_MUTEX(cpu_bitmask_lock);
static __cpuinitdata BLOCKING_NOTIFIER_HEAD(cpu_chain);
/* If set, cpu_up and cpu_down will return -EBUSY and do nothing.
* Should always be manipulated under cpu_add_remove_lock
*/
static int cpu_hotplug_disabled;
#ifdef CONFIG_HOTPLUG_CPU
/* Crappy recursive lock-takers in cpufreq! Complain loudly about idiots */
@ -108,30 +113,25 @@ static int take_cpu_down(void *unused)
return 0;
}
int cpu_down(unsigned int cpu)
/* Requires cpu_add_remove_lock to be held */
static int _cpu_down(unsigned int cpu)
{
int err;
struct task_struct *p;
cpumask_t old_allowed, tmp;
mutex_lock(&cpu_add_remove_lock);
if (num_online_cpus() == 1) {
err = -EBUSY;
goto out;
}
if (num_online_cpus() == 1)
return -EBUSY;
if (!cpu_online(cpu)) {
err = -EINVAL;
goto out;
}
if (!cpu_online(cpu))
return -EINVAL;
err = blocking_notifier_call_chain(&cpu_chain, CPU_DOWN_PREPARE,
(void *)(long)cpu);
if (err == NOTIFY_BAD) {
printk("%s: attempt to take down CPU %u failed\n",
__FUNCTION__, cpu);
err = -EINVAL;
goto out;
return -EINVAL;
}
/* Ensure that we are not runnable on dying cpu */
@ -179,22 +179,32 @@ out_thread:
err = kthread_stop(p);
out_allowed:
set_cpus_allowed(current, old_allowed);
out:
return err;
}
int cpu_down(unsigned int cpu)
{
int err = 0;
mutex_lock(&cpu_add_remove_lock);
if (cpu_hotplug_disabled)
err = -EBUSY;
else
err = _cpu_down(cpu);
mutex_unlock(&cpu_add_remove_lock);
return err;
}
#endif /*CONFIG_HOTPLUG_CPU*/
int __devinit cpu_up(unsigned int cpu)
/* Requires cpu_add_remove_lock to be held */
static int __devinit _cpu_up(unsigned int cpu)
{
int ret;
void *hcpu = (void *)(long)cpu;
mutex_lock(&cpu_add_remove_lock);
if (cpu_online(cpu) || !cpu_present(cpu)) {
ret = -EINVAL;
goto out;
}
if (cpu_online(cpu) || !cpu_present(cpu))
return -EINVAL;
ret = blocking_notifier_call_chain(&cpu_chain, CPU_UP_PREPARE, hcpu);
if (ret == NOTIFY_BAD) {
@ -219,7 +229,95 @@ out_notify:
if (ret != 0)
blocking_notifier_call_chain(&cpu_chain,
CPU_UP_CANCELED, hcpu);
out:
mutex_unlock(&cpu_add_remove_lock);
return ret;
}
int __devinit cpu_up(unsigned int cpu)
{
int err = 0;
mutex_lock(&cpu_add_remove_lock);
if (cpu_hotplug_disabled)
err = -EBUSY;
else
err = _cpu_up(cpu);
mutex_unlock(&cpu_add_remove_lock);
return err;
}
#ifdef CONFIG_SUSPEND_SMP
static cpumask_t frozen_cpus;
int disable_nonboot_cpus(void)
{
int cpu, first_cpu, error;
mutex_lock(&cpu_add_remove_lock);
first_cpu = first_cpu(cpu_present_map);
if (!cpu_online(first_cpu)) {
error = _cpu_up(first_cpu);
if (error) {
printk(KERN_ERR "Could not bring CPU%d up.\n",
first_cpu);
goto out;
}
}
error = set_cpus_allowed(current, cpumask_of_cpu(first_cpu));
if (error) {
printk(KERN_ERR "Could not run on CPU%d\n", first_cpu);
goto out;
}
/* We take down all of the non-boot CPUs in one shot to avoid races
* with the userspace trying to use the CPU hotplug at the same time
*/
cpus_clear(frozen_cpus);
printk("Disabling non-boot CPUs ...\n");
for_each_online_cpu(cpu) {
if (cpu == first_cpu)
continue;
error = _cpu_down(cpu);
if (!error) {
cpu_set(cpu, frozen_cpus);
printk("CPU%d is down\n", cpu);
} else {
printk(KERN_ERR "Error taking CPU%d down: %d\n",
cpu, error);
break;
}
}
if (!error) {
BUG_ON(num_online_cpus() > 1);
/* Make sure the CPUs won't be enabled by someone else */
cpu_hotplug_disabled = 1;
} else {
printk(KERN_ERR "Non-boot CPUs are not disabled");
}
out:
mutex_unlock(&cpu_add_remove_lock);
return error;
}
void enable_nonboot_cpus(void)
{
int cpu, error;
/* Allow everyone to use the CPU hotplug again */
mutex_lock(&cpu_add_remove_lock);
cpu_hotplug_disabled = 0;
mutex_unlock(&cpu_add_remove_lock);
printk("Enabling non-boot CPUs ...\n");
for_each_cpu_mask(cpu, frozen_cpus) {
error = cpu_up(cpu);
if (!error) {
printk("CPU%d is up\n", cpu);
continue;
}
printk(KERN_WARNING "Error taking CPU%d up: %d\n",
cpu, error);
}
cpus_clear(frozen_cpus);
}
#endif

View File

@ -7,6 +7,4 @@ obj-y := main.o process.o console.o
obj-$(CONFIG_PM_LEGACY) += pm.o
obj-$(CONFIG_SOFTWARE_SUSPEND) += swsusp.o disk.o snapshot.o swap.o user.o
obj-$(CONFIG_SUSPEND_SMP) += smp.o
obj-$(CONFIG_MAGIC_SYSRQ) += poweroff.o

View File

@ -18,6 +18,7 @@
#include <linux/fs.h>
#include <linux/mount.h>
#include <linux/pm.h>
#include <linux/cpu.h>
#include "power.h"
@ -72,7 +73,10 @@ static int prepare_processes(void)
int error;
pm_prepare_console();
disable_nonboot_cpus();
error = disable_nonboot_cpus();
if (error)
goto enable_cpus;
if (freeze_processes()) {
error = -EBUSY;
@ -84,6 +88,7 @@ static int prepare_processes(void)
return 0;
thaw:
thaw_processes();
enable_cpus:
enable_nonboot_cpus();
pm_restore_console();
return error;

View File

@ -16,6 +16,7 @@
#include <linux/init.h>
#include <linux/pm.h>
#include <linux/console.h>
#include <linux/cpu.h>
#include "power.h"
@ -51,7 +52,7 @@ void pm_set_ops(struct pm_ops * ops)
static int suspend_prepare(suspend_state_t state)
{
int error = 0;
int error;
unsigned int free_pages;
if (!pm_ops || !pm_ops->enter)
@ -59,12 +60,9 @@ static int suspend_prepare(suspend_state_t state)
pm_prepare_console();
disable_nonboot_cpus();
if (num_online_cpus() != 1) {
error = -EPERM;
error = disable_nonboot_cpus();
if (error)
goto Enable_cpu;
}
if (freeze_processes()) {
error = -EAGAIN;

View File

@ -1,62 +0,0 @@
/*
* drivers/power/smp.c - Functions for stopping other CPUs.
*
* Copyright 2004 Pavel Machek <pavel@suse.cz>
* Copyright (C) 2002-2003 Nigel Cunningham <ncunningham@clear.net.nz>
*
* This file is released under the GPLv2.
*/
#undef DEBUG
#include <linux/smp_lock.h>
#include <linux/interrupt.h>
#include <linux/suspend.h>
#include <linux/module.h>
#include <linux/cpu.h>
#include <asm/atomic.h>
#include <asm/tlbflush.h>
/* This is protected by pm_sem semaphore */
static cpumask_t frozen_cpus;
void disable_nonboot_cpus(void)
{
int cpu, error;
error = 0;
cpus_clear(frozen_cpus);
printk("Freezing cpus ...\n");
for_each_online_cpu(cpu) {
if (cpu == 0)
continue;
error = cpu_down(cpu);
if (!error) {
cpu_set(cpu, frozen_cpus);
printk("CPU%d is down\n", cpu);
continue;
}
printk("Error taking cpu %d down: %d\n", cpu, error);
}
BUG_ON(raw_smp_processor_id() != 0);
if (error)
panic("cpus not sleeping");
}
void enable_nonboot_cpus(void)
{
int cpu, error;
printk("Thawing cpus ...\n");
for_each_cpu_mask(cpu, frozen_cpus) {
error = cpu_up(cpu);
if (!error) {
printk("CPU%d is up\n", cpu);
continue;
}
printk("Error taking cpu %d up: %d\n", cpu, error);
panic("Not enough cpus");
}
cpus_clear(frozen_cpus);
}

View File

@ -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 @@ static int snapshot_ioctl(struct inode *inode, struct file *filp,
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;