330 lines
7.2 KiB
C
330 lines
7.2 KiB
C
/* CPU control.
|
|
* (C) 2001, 2002, 2003, 2004 Rusty Russell
|
|
*
|
|
* This code is licenced under the GPL.
|
|
*/
|
|
#include <linux/proc_fs.h>
|
|
#include <linux/smp.h>
|
|
#include <linux/init.h>
|
|
#include <linux/notifier.h>
|
|
#include <linux/sched.h>
|
|
#include <linux/unistd.h>
|
|
#include <linux/cpu.h>
|
|
#include <linux/module.h>
|
|
#include <linux/kthread.h>
|
|
#include <linux/stop_machine.h>
|
|
#include <linux/mutex.h>
|
|
|
|
/* This protects CPUs going up and down... */
|
|
static DEFINE_MUTEX(cpu_add_remove_lock);
|
|
static DEFINE_MUTEX(cpu_bitmask_lock);
|
|
|
|
static __cpuinitdata RAW_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 */
|
|
static struct task_struct *recursive;
|
|
static int recursive_depth;
|
|
|
|
void lock_cpu_hotplug(void)
|
|
{
|
|
struct task_struct *tsk = current;
|
|
|
|
if (tsk == recursive) {
|
|
static int warnings = 10;
|
|
if (warnings) {
|
|
printk(KERN_ERR "Lukewarm IQ detected in hotplug locking\n");
|
|
WARN_ON(1);
|
|
warnings--;
|
|
}
|
|
recursive_depth++;
|
|
return;
|
|
}
|
|
mutex_lock(&cpu_bitmask_lock);
|
|
recursive = tsk;
|
|
}
|
|
EXPORT_SYMBOL_GPL(lock_cpu_hotplug);
|
|
|
|
void unlock_cpu_hotplug(void)
|
|
{
|
|
WARN_ON(recursive != current);
|
|
if (recursive_depth) {
|
|
recursive_depth--;
|
|
return;
|
|
}
|
|
mutex_unlock(&cpu_bitmask_lock);
|
|
recursive = NULL;
|
|
}
|
|
EXPORT_SYMBOL_GPL(unlock_cpu_hotplug);
|
|
|
|
#endif /* CONFIG_HOTPLUG_CPU */
|
|
|
|
/* Need to know about CPUs going up/down? */
|
|
int __cpuinit register_cpu_notifier(struct notifier_block *nb)
|
|
{
|
|
int ret;
|
|
mutex_lock(&cpu_add_remove_lock);
|
|
ret = raw_notifier_chain_register(&cpu_chain, nb);
|
|
mutex_unlock(&cpu_add_remove_lock);
|
|
return ret;
|
|
}
|
|
|
|
#ifdef CONFIG_HOTPLUG_CPU
|
|
|
|
EXPORT_SYMBOL(register_cpu_notifier);
|
|
|
|
void unregister_cpu_notifier(struct notifier_block *nb)
|
|
{
|
|
mutex_lock(&cpu_add_remove_lock);
|
|
raw_notifier_chain_unregister(&cpu_chain, nb);
|
|
mutex_unlock(&cpu_add_remove_lock);
|
|
}
|
|
EXPORT_SYMBOL(unregister_cpu_notifier);
|
|
|
|
static inline void check_for_tasks(int cpu)
|
|
{
|
|
struct task_struct *p;
|
|
|
|
write_lock_irq(&tasklist_lock);
|
|
for_each_process(p) {
|
|
if (task_cpu(p) == cpu &&
|
|
(!cputime_eq(p->utime, cputime_zero) ||
|
|
!cputime_eq(p->stime, cputime_zero)))
|
|
printk(KERN_WARNING "Task %s (pid = %d) is on cpu %d\
|
|
(state = %ld, flags = %lx) \n",
|
|
p->comm, p->pid, cpu, p->state, p->flags);
|
|
}
|
|
write_unlock_irq(&tasklist_lock);
|
|
}
|
|
|
|
/* Take this CPU down. */
|
|
static int take_cpu_down(void *unused)
|
|
{
|
|
int err;
|
|
|
|
/* Ensure this CPU doesn't handle any more interrupts. */
|
|
err = __cpu_disable();
|
|
if (err < 0)
|
|
return err;
|
|
|
|
/* Force idle task to run as soon as we yield: it should
|
|
immediately notice cpu is offline and die quickly. */
|
|
sched_idle_next();
|
|
return 0;
|
|
}
|
|
|
|
/* 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;
|
|
|
|
if (num_online_cpus() == 1)
|
|
return -EBUSY;
|
|
|
|
if (!cpu_online(cpu))
|
|
return -EINVAL;
|
|
|
|
err = raw_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);
|
|
return -EINVAL;
|
|
}
|
|
|
|
/* Ensure that we are not runnable on dying cpu */
|
|
old_allowed = current->cpus_allowed;
|
|
tmp = CPU_MASK_ALL;
|
|
cpu_clear(cpu, tmp);
|
|
set_cpus_allowed(current, tmp);
|
|
|
|
mutex_lock(&cpu_bitmask_lock);
|
|
p = __stop_machine_run(take_cpu_down, NULL, cpu);
|
|
mutex_unlock(&cpu_bitmask_lock);
|
|
|
|
if (IS_ERR(p) || cpu_online(cpu)) {
|
|
/* CPU didn't die: tell everyone. Can't complain. */
|
|
if (raw_notifier_call_chain(&cpu_chain, CPU_DOWN_FAILED,
|
|
(void *)(long)cpu) == NOTIFY_BAD)
|
|
BUG();
|
|
|
|
if (IS_ERR(p)) {
|
|
err = PTR_ERR(p);
|
|
goto out_allowed;
|
|
}
|
|
goto out_thread;
|
|
}
|
|
|
|
/* Wait for it to sleep (leaving idle task). */
|
|
while (!idle_cpu(cpu))
|
|
yield();
|
|
|
|
/* This actually kills the CPU. */
|
|
__cpu_die(cpu);
|
|
|
|
/* Move it here so it can run. */
|
|
kthread_bind(p, get_cpu());
|
|
put_cpu();
|
|
|
|
/* CPU is completely dead: tell everyone. Too late to complain. */
|
|
if (raw_notifier_call_chain(&cpu_chain, CPU_DEAD,
|
|
(void *)(long)cpu) == NOTIFY_BAD)
|
|
BUG();
|
|
|
|
check_for_tasks(cpu);
|
|
|
|
out_thread:
|
|
err = kthread_stop(p);
|
|
out_allowed:
|
|
set_cpus_allowed(current, old_allowed);
|
|
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*/
|
|
|
|
/* Requires cpu_add_remove_lock to be held */
|
|
static int __devinit _cpu_up(unsigned int cpu)
|
|
{
|
|
int ret;
|
|
void *hcpu = (void *)(long)cpu;
|
|
|
|
if (cpu_online(cpu) || !cpu_present(cpu))
|
|
return -EINVAL;
|
|
|
|
ret = raw_notifier_call_chain(&cpu_chain, CPU_UP_PREPARE, hcpu);
|
|
if (ret == NOTIFY_BAD) {
|
|
printk("%s: attempt to bring up CPU %u failed\n",
|
|
__FUNCTION__, cpu);
|
|
ret = -EINVAL;
|
|
goto out_notify;
|
|
}
|
|
|
|
/* Arch-specific enabling code. */
|
|
mutex_lock(&cpu_bitmask_lock);
|
|
ret = __cpu_up(cpu);
|
|
mutex_unlock(&cpu_bitmask_lock);
|
|
if (ret != 0)
|
|
goto out_notify;
|
|
BUG_ON(!cpu_online(cpu));
|
|
|
|
/* Now call notifier in preparation. */
|
|
raw_notifier_call_chain(&cpu_chain, CPU_ONLINE, hcpu);
|
|
|
|
out_notify:
|
|
if (ret != 0)
|
|
raw_notifier_call_chain(&cpu_chain,
|
|
CPU_UP_CANCELED, hcpu);
|
|
|
|
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
|