[deliverable/linux.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/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 */
}

void touch_softlockup_watchdog(void)
{
	int this_cpu = raw_smp_processor_id();

	__raw_get_cpu_var(touch_timestamp) = get_timestamp(this_cpu);
}
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 &&
			print_timestamp < (touch_timestamp + 1)) ||
			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 every second: */
	if (now > (touch_timestamp + 1))
		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));
	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 ((tainted & TAINT_DIE) || did_panic)
		return;

	read_lock(&tasklist_lock);
	do_each_thread(g, t) {
		if (!--max_count)
			goto unlock;
		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
};

__init void spawn_softlockup_task(void)
{
	void *cpu = (void *)(long)smp_processor_id();
	int err = cpu_callback(&cpu_nfb, CPU_UP_PREPARE, cpu);

	BUG_ON(err == NOTIFY_BAD);
	cpu_callback(&cpu_nfb, CPU_ONLINE, cpu);
	register_cpu_notifier(&cpu_nfb);

	atomic_notifier_chain_register(&panic_notifier_list, &panic_block);
}
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 IM	15	#include <linux/kthread.h>
	16	#include <linux/notifier.h>
	17	#include <linux/module.h>
	18
43581a10 IM	19	#include <asm/irq_regs.h>
43581a10 IM	20
8446f1d3 IM	21	static DEFINE_SPINLOCK(print_lock);
8446f1d3 IM	22
6687a97d IM	23	static DEFINE_PER_CPU(unsigned long, touch_timestamp);
6687a97d IM	24	static DEFINE_PER_CPU(unsigned long, print_timestamp);
8446f1d3 IM	25	static DEFINE_PER_CPU(struct task_struct *, watchdog_task);
8446f1d3 IM	26
90739081	27	static int __read_mostly did_panic;
9383d967	28	int __read_mostly softlockup_thresh = 60;
6687a97d	29
9c44bc03 IM	30	/*
	31	* Should we panic (and reboot, if panic_timeout= is set) when a
	32	* soft-lockup occurs:
	33	*/
	34	unsigned int __read_mostly softlockup_panic =
	35	CONFIG_BOOTPARAM_SOFTLOCKUP_PANIC_VALUE;
	36
	37	static int __init softlockup_panic_setup(char *str)
	38	{
	39	softlockup_panic = simple_strtoul(str, NULL, 0);
	40
	41	return 1;
	42	}
	43	__setup("softlockup_panic=", softlockup_panic_setup);
	44
6687a97d IM	45	static int
6687a97d IM	46	softlock_panic(struct notifier_block this, unsigned long event, void ptr)
8446f1d3 IM	47	{
	48	did_panic = 1;
	49
	50	return NOTIFY_DONE;
	51	}
	52
	53	static struct notifier_block panic_block = {
	54	.notifier_call = softlock_panic,
	55	};
	56
966812dc JF	57	/*
	58	* Returns seconds, approximately. We don't need nanosecond
	59	* resolution, and we don't need to waste time with a big divide when
	60	* 2^30ns == 1.074s.
	61	*/
a3b13c23	62	static unsigned long get_timestamp(int this_cpu)
966812dc	63	{
82a1fcb9	64	return cpu_clock(this_cpu) >> 30LL; /* 2^30 ~= 10^9 */
966812dc JF	65	}
966812dc JF	66
8446f1d3 IM	67	void touch_softlockup_watchdog(void)
8446f1d3 IM	68	{
a3b13c23 IM	69	int this_cpu = raw_smp_processor_id();
	70
	71	__raw_get_cpu_var(touch_timestamp) = get_timestamp(this_cpu);
8446f1d3 IM	72	}
	73	EXPORT_SYMBOL(touch_softlockup_watchdog);
	74
04c9167f JF	75	void touch_all_softlockup_watchdogs(void)
	76	{
	77	int cpu;
	78
	79	/* Cause each CPU to re-update its timestamp rather than complain */
	80	for_each_online_cpu(cpu)
	81	per_cpu(touch_timestamp, cpu) = 0;
	82	}
	83	EXPORT_SYMBOL(touch_all_softlockup_watchdogs);
	84
8446f1d3 IM	85	/*
	86	* This callback runs from the timer interrupt, and checks
	87	* whether the watchdog thread has hung or not:
	88	*/
6687a97d	89	void softlockup_tick(void)
8446f1d3 IM	90	{
8446f1d3 IM	91	int this_cpu = smp_processor_id();
6687a97d	92	unsigned long touch_timestamp = per_cpu(touch_timestamp, this_cpu);
966812dc	93	unsigned long print_timestamp;
43581a10	94	struct pt_regs *regs = get_irq_regs();
966812dc	95	unsigned long now;
8446f1d3	96
9383d967 DS	97	/* Is detection switched off? */
	98	if (!per_cpu(watchdog_task, this_cpu) \|\| softlockup_thresh <= 0) {
	99	/* Be sure we don't false trigger if switched back on */
	100	if (touch_timestamp)
	101	per_cpu(touch_timestamp, this_cpu) = 0;
	102	return;
	103	}
	104
04c9167f JF	105	if (touch_timestamp == 0) {
04c9167f JF	106	touch_softlockup_watchdog();
966812dc	107	return;
04c9167f	108	}
966812dc JF	109
	110	print_timestamp = per_cpu(print_timestamp, this_cpu);
	111
	112	/* report at most once a second */
a115d5ca IM	113	if ((print_timestamp >= touch_timestamp &&
a115d5ca IM	114	print_timestamp < (touch_timestamp + 1)) \|\|
9383d967	115	did_panic) {
8446f1d3	116	return;
a115d5ca	117	}
8446f1d3	118
6687a97d IM	119	/* do not print during early bootup: */
	120	if (unlikely(system_state != SYSTEM_RUNNING)) {
	121	touch_softlockup_watchdog();
8446f1d3	122	return;
6687a97d	123	}
8446f1d3	124
a3b13c23	125	now = get_timestamp(this_cpu);
966812dc	126
ed50d6cb PZ	127	/* Wake up the high-prio watchdog task every second: */
	128	if (now > (touch_timestamp + 1))
	129	wake_up_process(per_cpu(watchdog_task, this_cpu));
	130
82a1fcb9	131	/* Warn about unreasonable delays: */
c4f3b63f	132	if (now <= (touch_timestamp + softlockup_thresh))
43581a10	133	return;
8446f1d3	134
43581a10 IM	135	per_cpu(print_timestamp, this_cpu) = touch_timestamp;
	136
	137	spin_lock(&print_lock);
c4f3b63f RT	138	printk(KERN_ERR "BUG: soft lockup - CPU#%d stuck for %lus! [%s:%d]\n",
c4f3b63f RT	139	this_cpu, now - touch_timestamp,
ba25f9dc	140	current->comm, task_pid_nr(current));
43581a10 IM	141	if (regs)
	142	show_regs(regs);
	143	else
6687a97d	144	dump_stack();
43581a10	145	spin_unlock(&print_lock);
9c44bc03 IM	146
	147	if (softlockup_panic)
	148	panic("softlockup: hung tasks");
8446f1d3 IM	149	}
8446f1d3 IM	150
82a1fcb9 IM	151	/*
	152	* Have a reasonable limit on the number of tasks checked:
	153	*/
90739081	154	unsigned long __read_mostly sysctl_hung_task_check_count = 1024;
82a1fcb9 IM	155
	156	/*
	157	* Zero means infinite timeout - no checking done:
	158	*/
90739081	159	unsigned long __read_mostly sysctl_hung_task_timeout_secs = 120;
82a1fcb9	160
90739081	161	unsigned long __read_mostly sysctl_hung_task_warnings = 10;
82a1fcb9 IM	162
	163	/*
	164	* Only do the hung-tasks check on one CPU:
	165	*/
	166	static int check_cpu __read_mostly = -1;
	167
	168	static void check_hung_task(struct task_struct *t, unsigned long now)
	169	{
	170	unsigned long switch_count = t->nvcsw + t->nivcsw;
	171
	172	if (t->flags & PF_FROZEN)
	173	return;
	174
	175	if (switch_count != t->last_switch_count \|\| !t->last_switch_timestamp) {
	176	t->last_switch_count = switch_count;
	177	t->last_switch_timestamp = now;
	178	return;
	179	}
	180	if ((long)(now - t->last_switch_timestamp) <
	181	sysctl_hung_task_timeout_secs)
	182	return;
	183	if (sysctl_hung_task_warnings < 0)
	184	return;
	185	sysctl_hung_task_warnings--;
	186
	187	/*
	188	* Ok, the task did not get scheduled for more than 2 minutes,
	189	* complain:
	190	*/
	191	printk(KERN_ERR "INFO: task %s:%d blocked for more than "
	192	"%ld seconds.\n", t->comm, t->pid,
	193	sysctl_hung_task_timeout_secs);
	194	printk(KERN_ERR "\"echo 0 > /proc/sys/kernel/hung_task_timeout_secs\""
	195	" disables this message.\n");
	196	sched_show_task(t);
	197	__debug_show_held_locks(t);
	198
	199	t->last_switch_timestamp = now;
	200	touch_nmi_watchdog();
9c44bc03 IM	201
	202	if (softlockup_panic)
	203	panic("softlockup: blocked tasks");
82a1fcb9 IM	204	}
	205
	206	/*
	207	* Check whether a TASK_UNINTERRUPTIBLE does not get woken up for
	208	* a really long time (120 seconds). If that happens, print out
	209	* a warning.
	210	*/
	211	static void check_hung_uninterruptible_tasks(int this_cpu)
	212	{
	213	int max_count = sysctl_hung_task_check_count;
	214	unsigned long now = get_timestamp(this_cpu);
	215	struct task_struct g, t;
	216
	217	/*
	218	* If the system crashed already then all bets are off,
	219	* do not report extra hung tasks:
	220	*/
	221	if ((tainted & TAINT_DIE) \|\| did_panic)
	222	return;
	223
	224	read_lock(&tasklist_lock);
	225	do_each_thread(g, t) {
	226	if (!--max_count)
ed50d6cb	227	goto unlock;
82a1fcb9 IM	228	if (t->state & TASK_UNINTERRUPTIBLE)
	229	check_hung_task(t, now);
	230	} while_each_thread(g, t);
ed50d6cb	231	unlock:
82a1fcb9 IM	232	read_unlock(&tasklist_lock);
	233	}
	234
8446f1d3 IM	235	/*
	236	* The watchdog thread - runs every second and touches the timestamp.
	237	*/
a5f2ce3c	238	static int watchdog(void *__bind_cpu)
8446f1d3	239	{
02fb6149	240	struct sched_param param = { .sched_priority = MAX_RT_PRIO-1 };
82a1fcb9	241	int this_cpu = (long)__bind_cpu;
8446f1d3 IM	242
8446f1d3 IM	243	sched_setscheduler(current, SCHED_FIFO, &param);
8446f1d3	244
966812dc JF	245	/* initialize timestamp */
	246	touch_softlockup_watchdog();
	247
7be2a03e	248	set_current_state(TASK_INTERRUPTIBLE);
8446f1d3	249	/*
6687a97d	250	* Run briefly once per second to reset the softlockup timestamp.
82a1fcb9	251	* If this gets delayed for more than 60 seconds then the
6687a97d	252	* debug-printout triggers in softlockup_tick().
8446f1d3 IM	253	*/
8446f1d3 IM	254	while (!kthread_should_stop()) {
8446f1d3	255	touch_softlockup_watchdog();
ed50d6cb PZ	256	schedule();
	257
	258	if (kthread_should_stop())
	259	break;
82a1fcb9	260
7be2a03e DA	261	if (this_cpu == check_cpu) {
	262	if (sysctl_hung_task_timeout_secs)
	263	check_hung_uninterruptible_tasks(this_cpu);
	264	}
ed50d6cb	265
7be2a03e	266	set_current_state(TASK_INTERRUPTIBLE);
8446f1d3	267	}
7be2a03e	268	__set_current_state(TASK_RUNNING);
8446f1d3 IM	269
	270	return 0;
	271	}
	272
	273	/*
	274	* Create/destroy watchdog threads as CPUs come and go:
	275	*/
8c78f307	276	static int __cpuinit
8446f1d3 IM	277	cpu_callback(struct notifier_block nfb, unsigned long action, void hcpu)
	278	{
	279	int hotcpu = (unsigned long)hcpu;
	280	struct task_struct *p;
	281
	282	switch (action) {
	283	case CPU_UP_PREPARE:
8bb78442	284	case CPU_UP_PREPARE_FROZEN:
8446f1d3 IM	285	BUG_ON(per_cpu(watchdog_task, hotcpu));
	286	p = kthread_create(watchdog, hcpu, "watchdog/%d", hotcpu);
	287	if (IS_ERR(p)) {
a5f2ce3c	288	printk(KERN_ERR "watchdog for %i failed\n", hotcpu);
8446f1d3 IM	289	return NOTIFY_BAD;
8446f1d3 IM	290	}
a5f2ce3c IM	291	per_cpu(touch_timestamp, hotcpu) = 0;
a5f2ce3c IM	292	per_cpu(watchdog_task, hotcpu) = p;
8446f1d3	293	kthread_bind(p, hotcpu);
a5f2ce3c	294	break;
8446f1d3	295	case CPU_ONLINE:
8bb78442	296	case CPU_ONLINE_FROZEN:
82a1fcb9	297	check_cpu = any_online_cpu(cpu_online_map);
8446f1d3 IM	298	wake_up_process(per_cpu(watchdog_task, hotcpu));
	299	break;
	300	#ifdef CONFIG_HOTPLUG_CPU
82a1fcb9 IM	301	case CPU_DOWN_PREPARE:
	302	case CPU_DOWN_PREPARE_FROZEN:
	303	if (hotcpu == check_cpu) {
	304	cpumask_t temp_cpu_online_map = cpu_online_map;
	305
	306	cpu_clear(hotcpu, temp_cpu_online_map);
	307	check_cpu = any_online_cpu(temp_cpu_online_map);
	308	}
	309	break;
ed50d6cb PZ	310
	311	case CPU_UP_CANCELED:
	312	case CPU_UP_CANCELED_FROZEN:
	313	if (!per_cpu(watchdog_task, hotcpu))
	314	break;
	315	/* Unbind so it can run. Fall thru. */
	316	kthread_bind(per_cpu(watchdog_task, hotcpu),
	317	any_online_cpu(cpu_online_map));
8446f1d3	318	case CPU_DEAD:
8bb78442	319	case CPU_DEAD_FROZEN:
8446f1d3 IM	320	p = per_cpu(watchdog_task, hotcpu);
	321	per_cpu(watchdog_task, hotcpu) = NULL;
	322	kthread_stop(p);
	323	break;
	324	#endif /* CONFIG_HOTPLUG_CPU */
a5f2ce3c	325	}
8446f1d3 IM	326	return NOTIFY_OK;
	327	}
	328
8c78f307	329	static struct notifier_block __cpuinitdata cpu_nfb = {
8446f1d3 IM	330	.notifier_call = cpu_callback
	331	};
	332
	333	__init void spawn_softlockup_task(void)
	334	{
	335	void cpu = (void )(long)smp_processor_id();
07dccf33	336	int err = cpu_callback(&cpu_nfb, CPU_UP_PREPARE, cpu);
8446f1d3	337
07dccf33	338	BUG_ON(err == NOTIFY_BAD);
8446f1d3 IM	339	cpu_callback(&cpu_nfb, CPU_ONLINE, cpu);
	340	register_cpu_notifier(&cpu_nfb);
	341
e041c683	342	atomic_notifier_chain_register(&panic_notifier_list, &panic_block);
8446f1d3	343	}