[linux-2.6-block.git] / kernel / softlockup.c

/*
 * Detect Soft Lockups
 *
 * started by Ingo Molnar, Copyright (C) 2005, 2006 Red Hat, Inc.
 *
 * this code detects soft lockups: incidents in where on a CPU
 * the kernel does not reschedule for 10 seconds or more.
 */
#include <linux/mm.h>
#include <linux/cpu.h>
#include <linux/nmi.h>
#include <linux/init.h>
#include <linux/delay.h>
#include <linux/freezer.h>
#include <linux/kthread.h>
#include <linux/lockdep.h>
#include <linux/notifier.h>
#include <linux/module.h>

#include <asm/irq_regs.h>

static DEFINE_SPINLOCK(print_lock);

static DEFINE_PER_CPU(unsigned long, touch_timestamp);
static DEFINE_PER_CPU(unsigned long, print_timestamp);
static DEFINE_PER_CPU(struct task_struct *, watchdog_task);

static int __read_mostly did_panic;
int __read_mostly softlockup_thresh = 60;

/*
 * Should we panic (and reboot, if panic_timeout= is set) when a
 * soft-lockup occurs:
 */
unsigned int __read_mostly softlockup_panic =
				CONFIG_BOOTPARAM_SOFTLOCKUP_PANIC_VALUE;

static int __init softlockup_panic_setup(char *str)
{
	softlockup_panic = simple_strtoul(str, NULL, 0);

	return 1;
}
__setup("softlockup_panic=", softlockup_panic_setup);

static int
softlock_panic(struct notifier_block *this, unsigned long event, void *ptr)
{
	did_panic = 1;

	return NOTIFY_DONE;
}

static struct notifier_block panic_block = {
	.notifier_call = softlock_panic,
};

/*
 * Returns seconds, approximately.  We don't need nanosecond
 * resolution, and we don't need to waste time with a big divide when
 * 2^30ns == 1.074s.
 */
static unsigned long get_timestamp(int this_cpu)
{
	return cpu_clock(this_cpu) >> 30LL;  /* 2^30 ~= 10^9 */
}

static void __touch_softlockup_watchdog(void)
{
	int this_cpu = raw_smp_processor_id();

	__raw_get_cpu_var(touch_timestamp) = get_timestamp(this_cpu);
}

void touch_softlockup_watchdog(void)
{
	__raw_get_cpu_var(touch_timestamp) = 0;
}
EXPORT_SYMBOL(touch_softlockup_watchdog);

void touch_all_softlockup_watchdogs(void)
{
	int cpu;

	/* Cause each CPU to re-update its timestamp rather than complain */
	for_each_online_cpu(cpu)
		per_cpu(touch_timestamp, cpu) = 0;
}
EXPORT_SYMBOL(touch_all_softlockup_watchdogs);

/*
 * This callback runs from the timer interrupt, and checks
 * whether the watchdog thread has hung or not:
 */
void softlockup_tick(void)
{
	int this_cpu = smp_processor_id();
	unsigned long touch_timestamp = per_cpu(touch_timestamp, this_cpu);
	unsigned long print_timestamp;
	struct pt_regs *regs = get_irq_regs();
	unsigned long now;

	/* Is detection switched off? */
	if (!per_cpu(watchdog_task, this_cpu) || softlockup_thresh <= 0) {
		/* Be sure we don't false trigger if switched back on */
		if (touch_timestamp)
			per_cpu(touch_timestamp, this_cpu) = 0;
		return;
	}

	if (touch_timestamp == 0) {
		__touch_softlockup_watchdog();
		return;
	}

	print_timestamp = per_cpu(print_timestamp, this_cpu);

	/* report at most once a second */
	if (print_timestamp == touch_timestamp || did_panic)
		return;

	/* do not print during early bootup: */
	if (unlikely(system_state != SYSTEM_RUNNING)) {
		__touch_softlockup_watchdog();
		return;
	}

	now = get_timestamp(this_cpu);

	/*
	 * Wake up the high-prio watchdog task twice per
	 * threshold timespan.
	 */
	if (now > touch_timestamp + softlockup_thresh/2)
		wake_up_process(per_cpu(watchdog_task, this_cpu));

	/* Warn about unreasonable delays: */
	if (now <= (touch_timestamp + softlockup_thresh))
		return;

	per_cpu(print_timestamp, this_cpu) = touch_timestamp;

	spin_lock(&print_lock);
	printk(KERN_ERR "BUG: soft lockup - CPU#%d stuck for %lus! [%s:%d]\n",
			this_cpu, now - touch_timestamp,
			current->comm, task_pid_nr(current));
	print_modules();
	print_irqtrace_events(current);
	if (regs)
		show_regs(regs);
	else
		dump_stack();
	spin_unlock(&print_lock);

	if (softlockup_panic)
		panic("softlockup: hung tasks");
}

/*
 * Have a reasonable limit on the number of tasks checked:
 */
unsigned long __read_mostly sysctl_hung_task_check_count = 1024;

/*
 * Zero means infinite timeout - no checking done:
 */
unsigned long __read_mostly sysctl_hung_task_timeout_secs = 120;

unsigned long __read_mostly sysctl_hung_task_warnings = 10;

/*
 * Only do the hung-tasks check on one CPU:
 */
static int check_cpu __read_mostly = -1;

static void check_hung_task(struct task_struct *t, unsigned long now)
{
	unsigned long switch_count = t->nvcsw + t->nivcsw;

	if (t->flags & PF_FROZEN)
		return;

	if (switch_count != t->last_switch_count || !t->last_switch_timestamp) {
		t->last_switch_count = switch_count;
		t->last_switch_timestamp = now;
		return;
	}
	if ((long)(now - t->last_switch_timestamp) <
					sysctl_hung_task_timeout_secs)
		return;
	if (sysctl_hung_task_warnings < 0)
		return;
	sysctl_hung_task_warnings--;

	/*
	 * Ok, the task did not get scheduled for more than 2 minutes,
	 * complain:
	 */
	printk(KERN_ERR "INFO: task %s:%d blocked for more than "
			"%ld seconds.\n", t->comm, t->pid,
			sysctl_hung_task_timeout_secs);
	printk(KERN_ERR "\"echo 0 > /proc/sys/kernel/hung_task_timeout_secs\""
			" disables this message.\n");
	sched_show_task(t);
	__debug_show_held_locks(t);

	t->last_switch_timestamp = now;
	touch_nmi_watchdog();

	if (softlockup_panic)
		panic("softlockup: blocked tasks");
}

/*
 * Check whether a TASK_UNINTERRUPTIBLE does not get woken up for
 * a really long time (120 seconds). If that happens, print out
 * a warning.
 */
static void check_hung_uninterruptible_tasks(int this_cpu)
{
	int max_count = sysctl_hung_task_check_count;
	unsigned long now = get_timestamp(this_cpu);
	struct task_struct *g, *t;

	/*
	 * If the system crashed already then all bets are off,
	 * do not report extra hung tasks:
	 */
	if (test_taint(TAINT_DIE) || did_panic)
		return;

	read_lock(&tasklist_lock);
	do_each_thread(g, t) {
		if (!--max_count)
			goto unlock;
		/* use "==" to skip the TASK_KILLABLE tasks waiting on NFS */
		if (t->state == TASK_UNINTERRUPTIBLE)
			check_hung_task(t, now);
	} while_each_thread(g, t);
 unlock:
	read_unlock(&tasklist_lock);
}

/*
 * The watchdog thread - runs every second and touches the timestamp.
 */
static int watchdog(void *__bind_cpu)
{
	struct sched_param param = { .sched_priority = MAX_RT_PRIO-1 };
	int this_cpu = (long)__bind_cpu;

	sched_setscheduler(current, SCHED_FIFO, &param);

	/* initialize timestamp */
	__touch_softlockup_watchdog();

	set_current_state(TASK_INTERRUPTIBLE);
	/*
	 * Run briefly once per second to reset the softlockup timestamp.
	 * If this gets delayed for more than 60 seconds then the
	 * debug-printout triggers in softlockup_tick().
	 */
	while (!kthread_should_stop()) {
		__touch_softlockup_watchdog();
		schedule();

		if (kthread_should_stop())
			break;

		if (this_cpu == check_cpu) {
			if (sysctl_hung_task_timeout_secs)
				check_hung_uninterruptible_tasks(this_cpu);
		}

		set_current_state(TASK_INTERRUPTIBLE);
	}
	__set_current_state(TASK_RUNNING);

	return 0;
}

/*
 * Create/destroy watchdog threads as CPUs come and go:
 */
static int __cpuinit
cpu_callback(struct notifier_block *nfb, unsigned long action, void *hcpu)
{
	int hotcpu = (unsigned long)hcpu;
	struct task_struct *p;

	switch (action) {
	case CPU_UP_PREPARE:
	case CPU_UP_PREPARE_FROZEN:
		BUG_ON(per_cpu(watchdog_task, hotcpu));
		p = kthread_create(watchdog, hcpu, "watchdog/%d", hotcpu);
		if (IS_ERR(p)) {
			printk(KERN_ERR "watchdog for %i failed\n", hotcpu);
			return NOTIFY_BAD;
		}
		per_cpu(touch_timestamp, hotcpu) = 0;
		per_cpu(watchdog_task, hotcpu) = p;
		kthread_bind(p, hotcpu);
		break;
	case CPU_ONLINE:
	case CPU_ONLINE_FROZEN:
		check_cpu = any_online_cpu(cpu_online_map);
		wake_up_process(per_cpu(watchdog_task, hotcpu));
		break;
#ifdef CONFIG_HOTPLUG_CPU
	case CPU_DOWN_PREPARE:
	case CPU_DOWN_PREPARE_FROZEN:
		if (hotcpu == check_cpu) {
			cpumask_t temp_cpu_online_map = cpu_online_map;

			cpu_clear(hotcpu, temp_cpu_online_map);
			check_cpu = any_online_cpu(temp_cpu_online_map);
		}
		break;

	case CPU_UP_CANCELED:
	case CPU_UP_CANCELED_FROZEN:
		if (!per_cpu(watchdog_task, hotcpu))
			break;
		/* Unbind so it can run.  Fall thru. */
		kthread_bind(per_cpu(watchdog_task, hotcpu),
			     any_online_cpu(cpu_online_map));
	case CPU_DEAD:
	case CPU_DEAD_FROZEN:
		p = per_cpu(watchdog_task, hotcpu);
		per_cpu(watchdog_task, hotcpu) = NULL;
		kthread_stop(p);
		break;
#endif /* CONFIG_HOTPLUG_CPU */
	}
	return NOTIFY_OK;
}

static struct notifier_block __cpuinitdata cpu_nfb = {
	.notifier_call = cpu_callback
};

static int __initdata nosoftlockup;

static int __init nosoftlockup_setup(char *str)
{
	nosoftlockup = 1;
	return 1;
}
__setup("nosoftlockup", nosoftlockup_setup);

static int __init spawn_softlockup_task(void)
{
	void *cpu = (void *)(long)smp_processor_id();
	int err;

	if (nosoftlockup)
		return 0;

	err = cpu_callback(&cpu_nfb, CPU_UP_PREPARE, cpu);
	if (err == NOTIFY_BAD) {
		BUG();
		return 1;
	}
	cpu_callback(&cpu_nfb, CPU_ONLINE, cpu);
	register_cpu_notifier(&cpu_nfb);

	atomic_notifier_chain_register(&panic_notifier_list, &panic_block);

	return 0;
}
early_initcall(spawn_softlockup_task);
Commit	Line	Data
8446f1d3 IM	1	/*
	2	* Detect Soft Lockups
	3	*
6687a97d	4	* started by Ingo Molnar, Copyright (C) 2005, 2006 Red Hat, Inc.
8446f1d3 IM	5	*
	6	* this code detects soft lockups: incidents in where on a CPU
	7	* the kernel does not reschedule for 10 seconds or more.
	8	*/
8446f1d3 IM	9	#include <linux/mm.h>
8446f1d3 IM	10	#include <linux/cpu.h>
82a1fcb9	11	#include <linux/nmi.h>
8446f1d3 IM	12	#include <linux/init.h>
8446f1d3 IM	13	#include <linux/delay.h>
83144186	14	#include <linux/freezer.h>
8446f1d3	15	#include <linux/kthread.h>
8d5be7f4	16	#include <linux/lockdep.h>
8446f1d3 IM	17	#include <linux/notifier.h>
	18	#include <linux/module.h>
	19
43581a10 IM	20	#include <asm/irq_regs.h>
43581a10 IM	21
8446f1d3 IM	22	static DEFINE_SPINLOCK(print_lock);
8446f1d3 IM	23
6687a97d IM	24	static DEFINE_PER_CPU(unsigned long, touch_timestamp);
6687a97d IM	25	static DEFINE_PER_CPU(unsigned long, print_timestamp);
8446f1d3 IM	26	static DEFINE_PER_CPU(struct task_struct *, watchdog_task);
8446f1d3 IM	27
90739081	28	static int __read_mostly did_panic;
9383d967	29	int __read_mostly softlockup_thresh = 60;
6687a97d	30
9c44bc03 IM	31	/*
	32	* Should we panic (and reboot, if panic_timeout= is set) when a
	33	* soft-lockup occurs:
	34	*/
	35	unsigned int __read_mostly softlockup_panic =
	36	CONFIG_BOOTPARAM_SOFTLOCKUP_PANIC_VALUE;
	37
	38	static int __init softlockup_panic_setup(char *str)
	39	{
	40	softlockup_panic = simple_strtoul(str, NULL, 0);
	41
	42	return 1;
	43	}
	44	__setup("softlockup_panic=", softlockup_panic_setup);
	45
6687a97d IM	46	static int
6687a97d IM	47	softlock_panic(struct notifier_block this, unsigned long event, void ptr)
8446f1d3 IM	48	{
	49	did_panic = 1;
	50
	51	return NOTIFY_DONE;
	52	}
	53
	54	static struct notifier_block panic_block = {
	55	.notifier_call = softlock_panic,
	56	};
	57
966812dc JF	58	/*
	59	* Returns seconds, approximately. We don't need nanosecond
	60	* resolution, and we don't need to waste time with a big divide when
	61	* 2^30ns == 1.074s.
	62	*/
a3b13c23	63	static unsigned long get_timestamp(int this_cpu)
966812dc	64	{
82a1fcb9	65	return cpu_clock(this_cpu) >> 30LL; /* 2^30 ~= 10^9 */
966812dc JF	66	}
966812dc JF	67
8c2238ea	68	static void __touch_softlockup_watchdog(void)
8446f1d3	69	{
a3b13c23 IM	70	int this_cpu = raw_smp_processor_id();
	71
	72	__raw_get_cpu_var(touch_timestamp) = get_timestamp(this_cpu);
8446f1d3	73	}
8c2238ea JW	74
	75	void touch_softlockup_watchdog(void)
	76	{
	77	__raw_get_cpu_var(touch_timestamp) = 0;
	78	}
8446f1d3 IM	79	EXPORT_SYMBOL(touch_softlockup_watchdog);
8446f1d3 IM	80
04c9167f JF	81	void touch_all_softlockup_watchdogs(void)
	82	{
	83	int cpu;
	84
	85	/* Cause each CPU to re-update its timestamp rather than complain */
	86	for_each_online_cpu(cpu)
	87	per_cpu(touch_timestamp, cpu) = 0;
	88	}
	89	EXPORT_SYMBOL(touch_all_softlockup_watchdogs);
	90
8446f1d3 IM	91	/*
	92	* This callback runs from the timer interrupt, and checks
	93	* whether the watchdog thread has hung or not:
	94	*/
6687a97d	95	void softlockup_tick(void)
8446f1d3 IM	96	{
8446f1d3 IM	97	int this_cpu = smp_processor_id();
6687a97d	98	unsigned long touch_timestamp = per_cpu(touch_timestamp, this_cpu);
966812dc	99	unsigned long print_timestamp;
43581a10	100	struct pt_regs *regs = get_irq_regs();
966812dc	101	unsigned long now;
8446f1d3	102
9383d967 DS	103	/* Is detection switched off? */
	104	if (!per_cpu(watchdog_task, this_cpu) \|\| softlockup_thresh <= 0) {
	105	/* Be sure we don't false trigger if switched back on */
	106	if (touch_timestamp)
	107	per_cpu(touch_timestamp, this_cpu) = 0;
	108	return;
	109	}
	110
04c9167f	111	if (touch_timestamp == 0) {
8c2238ea	112	__touch_softlockup_watchdog();
966812dc	113	return;
04c9167f	114	}
966812dc JF	115
	116	print_timestamp = per_cpu(print_timestamp, this_cpu);
	117
	118	/* report at most once a second */
3e2f69fd	119	if (print_timestamp == touch_timestamp \|\| did_panic)
8446f1d3 IM	120	return;
8446f1d3 IM	121
6687a97d IM	122	/* do not print during early bootup: */
6687a97d IM	123	if (unlikely(system_state != SYSTEM_RUNNING)) {
8c2238ea	124	__touch_softlockup_watchdog();
8446f1d3	125	return;
6687a97d	126	}
8446f1d3	127
a3b13c23	128	now = get_timestamp(this_cpu);
966812dc	129
dd7a1e56 JW	130	/*
	131	* Wake up the high-prio watchdog task twice per
	132	* threshold timespan.
	133	*/
	134	if (now > touch_timestamp + softlockup_thresh/2)
ed50d6cb PZ	135	wake_up_process(per_cpu(watchdog_task, this_cpu));
ed50d6cb PZ	136
82a1fcb9	137	/* Warn about unreasonable delays: */
c4f3b63f	138	if (now <= (touch_timestamp + softlockup_thresh))
43581a10	139	return;
8446f1d3	140
43581a10 IM	141	per_cpu(print_timestamp, this_cpu) = touch_timestamp;
	142
	143	spin_lock(&print_lock);
c4f3b63f RT	144	printk(KERN_ERR "BUG: soft lockup - CPU#%d stuck for %lus! [%s:%d]\n",
c4f3b63f RT	145	this_cpu, now - touch_timestamp,
ba25f9dc	146	current->comm, task_pid_nr(current));
688c9175	147	print_modules();
8d5be7f4	148	print_irqtrace_events(current);
43581a10 IM	149	if (regs)
	150	show_regs(regs);
	151	else
6687a97d	152	dump_stack();
43581a10	153	spin_unlock(&print_lock);
9c44bc03 IM	154
	155	if (softlockup_panic)
	156	panic("softlockup: hung tasks");
8446f1d3 IM	157	}
8446f1d3 IM	158
82a1fcb9 IM	159	/*
	160	* Have a reasonable limit on the number of tasks checked:
	161	*/
90739081	162	unsigned long __read_mostly sysctl_hung_task_check_count = 1024;
82a1fcb9 IM	163
	164	/*
	165	* Zero means infinite timeout - no checking done:
	166	*/
90739081	167	unsigned long __read_mostly sysctl_hung_task_timeout_secs = 120;
82a1fcb9	168
90739081	169	unsigned long __read_mostly sysctl_hung_task_warnings = 10;
82a1fcb9 IM	170
	171	/*
	172	* Only do the hung-tasks check on one CPU:
	173	*/
	174	static int check_cpu __read_mostly = -1;
	175
	176	static void check_hung_task(struct task_struct *t, unsigned long now)
	177	{
	178	unsigned long switch_count = t->nvcsw + t->nivcsw;
	179
	180	if (t->flags & PF_FROZEN)
	181	return;
	182
	183	if (switch_count != t->last_switch_count \|\| !t->last_switch_timestamp) {
	184	t->last_switch_count = switch_count;
	185	t->last_switch_timestamp = now;
	186	return;
	187	}
	188	if ((long)(now - t->last_switch_timestamp) <
	189	sysctl_hung_task_timeout_secs)
	190	return;
	191	if (sysctl_hung_task_warnings < 0)
	192	return;
	193	sysctl_hung_task_warnings--;
	194
	195	/*
	196	* Ok, the task did not get scheduled for more than 2 minutes,
	197	* complain:
	198	*/
	199	printk(KERN_ERR "INFO: task %s:%d blocked for more than "
	200	"%ld seconds.\n", t->comm, t->pid,
	201	sysctl_hung_task_timeout_secs);
	202	printk(KERN_ERR "\"echo 0 > /proc/sys/kernel/hung_task_timeout_secs\""
	203	" disables this message.\n");
	204	sched_show_task(t);
	205	__debug_show_held_locks(t);
	206
	207	t->last_switch_timestamp = now;
	208	touch_nmi_watchdog();
9c44bc03 IM	209
	210	if (softlockup_panic)
	211	panic("softlockup: blocked tasks");
82a1fcb9 IM	212	}
	213
	214	/*
	215	* Check whether a TASK_UNINTERRUPTIBLE does not get woken up for
	216	* a really long time (120 seconds). If that happens, print out
	217	* a warning.
	218	*/
	219	static void check_hung_uninterruptible_tasks(int this_cpu)
	220	{
	221	int max_count = sysctl_hung_task_check_count;
	222	unsigned long now = get_timestamp(this_cpu);
	223	struct task_struct g, t;
	224
	225	/*
	226	* If the system crashed already then all bets are off,
	227	* do not report extra hung tasks:
	228	*/
25ddbb18	229	if (test_taint(TAINT_DIE) \|\| did_panic)
82a1fcb9 IM	230	return;
	231
	232	read_lock(&tasklist_lock);
	233	do_each_thread(g, t) {
	234	if (!--max_count)
ed50d6cb	235	goto unlock;
cbaed698 ON	236	/* use "==" to skip the TASK_KILLABLE tasks waiting on NFS */
cbaed698 ON	237	if (t->state == TASK_UNINTERRUPTIBLE)
82a1fcb9 IM	238	check_hung_task(t, now);
82a1fcb9 IM	239	} while_each_thread(g, t);
ed50d6cb	240	unlock:
82a1fcb9 IM	241	read_unlock(&tasklist_lock);
	242	}
	243
8446f1d3 IM	244	/*
	245	* The watchdog thread - runs every second and touches the timestamp.
	246	*/
a5f2ce3c	247	static int watchdog(void *__bind_cpu)
8446f1d3	248	{
02fb6149	249	struct sched_param param = { .sched_priority = MAX_RT_PRIO-1 };
82a1fcb9	250	int this_cpu = (long)__bind_cpu;
8446f1d3 IM	251
8446f1d3 IM	252	sched_setscheduler(current, SCHED_FIFO, &param);
8446f1d3	253
966812dc	254	/* initialize timestamp */
8c2238ea	255	__touch_softlockup_watchdog();
966812dc	256
7be2a03e	257	set_current_state(TASK_INTERRUPTIBLE);
8446f1d3	258	/*
6687a97d	259	* Run briefly once per second to reset the softlockup timestamp.
82a1fcb9	260	* If this gets delayed for more than 60 seconds then the
6687a97d	261	* debug-printout triggers in softlockup_tick().
8446f1d3 IM	262	*/
8446f1d3 IM	263	while (!kthread_should_stop()) {
8c2238ea	264	__touch_softlockup_watchdog();
ed50d6cb PZ	265	schedule();
	266
	267	if (kthread_should_stop())
	268	break;
82a1fcb9	269
7be2a03e DA	270	if (this_cpu == check_cpu) {
	271	if (sysctl_hung_task_timeout_secs)
	272	check_hung_uninterruptible_tasks(this_cpu);
	273	}
ed50d6cb	274
7be2a03e	275	set_current_state(TASK_INTERRUPTIBLE);
8446f1d3	276	}
7be2a03e	277	__set_current_state(TASK_RUNNING);
8446f1d3 IM	278
	279	return 0;
	280	}
	281
	282	/*
	283	* Create/destroy watchdog threads as CPUs come and go:
	284	*/
8c78f307	285	static int __cpuinit
8446f1d3 IM	286	cpu_callback(struct notifier_block nfb, unsigned long action, void hcpu)
	287	{
	288	int hotcpu = (unsigned long)hcpu;
	289	struct task_struct *p;
	290
	291	switch (action) {
	292	case CPU_UP_PREPARE:
8bb78442	293	case CPU_UP_PREPARE_FROZEN:
8446f1d3 IM	294	BUG_ON(per_cpu(watchdog_task, hotcpu));
	295	p = kthread_create(watchdog, hcpu, "watchdog/%d", hotcpu);
	296	if (IS_ERR(p)) {
a5f2ce3c	297	printk(KERN_ERR "watchdog for %i failed\n", hotcpu);
8446f1d3 IM	298	return NOTIFY_BAD;
8446f1d3 IM	299	}
a5f2ce3c IM	300	per_cpu(touch_timestamp, hotcpu) = 0;
a5f2ce3c IM	301	per_cpu(watchdog_task, hotcpu) = p;
8446f1d3	302	kthread_bind(p, hotcpu);
a5f2ce3c	303	break;
8446f1d3	304	case CPU_ONLINE:
8bb78442	305	case CPU_ONLINE_FROZEN:
82a1fcb9	306	check_cpu = any_online_cpu(cpu_online_map);
8446f1d3 IM	307	wake_up_process(per_cpu(watchdog_task, hotcpu));
	308	break;
	309	#ifdef CONFIG_HOTPLUG_CPU
82a1fcb9 IM	310	case CPU_DOWN_PREPARE:
	311	case CPU_DOWN_PREPARE_FROZEN:
	312	if (hotcpu == check_cpu) {
	313	cpumask_t temp_cpu_online_map = cpu_online_map;
	314
	315	cpu_clear(hotcpu, temp_cpu_online_map);
	316	check_cpu = any_online_cpu(temp_cpu_online_map);
	317	}
	318	break;
ed50d6cb PZ	319
	320	case CPU_UP_CANCELED:
	321	case CPU_UP_CANCELED_FROZEN:
	322	if (!per_cpu(watchdog_task, hotcpu))
	323	break;
	324	/* Unbind so it can run. Fall thru. */
	325	kthread_bind(per_cpu(watchdog_task, hotcpu),
	326	any_online_cpu(cpu_online_map));
8446f1d3	327	case CPU_DEAD:
8bb78442	328	case CPU_DEAD_FROZEN:
8446f1d3 IM	329	p = per_cpu(watchdog_task, hotcpu);
	330	per_cpu(watchdog_task, hotcpu) = NULL;
	331	kthread_stop(p);
	332	break;
	333	#endif /* CONFIG_HOTPLUG_CPU */
a5f2ce3c	334	}
8446f1d3 IM	335	return NOTIFY_OK;
	336	}
	337
8c78f307	338	static struct notifier_block __cpuinitdata cpu_nfb = {
8446f1d3 IM	339	.notifier_call = cpu_callback
	340	};
	341
7babe8db EGM	342	static int __initdata nosoftlockup;
	343
	344	static int __init nosoftlockup_setup(char *str)
	345	{
	346	nosoftlockup = 1;
	347	return 1;
	348	}
	349	__setup("nosoftlockup", nosoftlockup_setup);
	350
	351	static int __init spawn_softlockup_task(void)
8446f1d3 IM	352	{
8446f1d3 IM	353	void cpu = (void )(long)smp_processor_id();
7babe8db	354	int err;
8446f1d3	355
7babe8db EGM	356	if (nosoftlockup)
	357	return 0;
	358
	359	err = cpu_callback(&cpu_nfb, CPU_UP_PREPARE, cpu);
	360	if (err == NOTIFY_BAD) {
	361	BUG();
	362	return 1;
	363	}
8446f1d3 IM	364	cpu_callback(&cpu_nfb, CPU_ONLINE, cpu);
	365	register_cpu_notifier(&cpu_nfb);
	366
e041c683	367	atomic_notifier_chain_register(&panic_notifier_list, &panic_block);
7babe8db EGM	368
7babe8db EGM	369	return 0;
8446f1d3	370	}
7babe8db	371	early_initcall(spawn_softlockup_task);