[net-next-2.6.git] / kernel / watchdog.c

/*
 * Detect hard and soft lockups on a system
 *
 * started by Don Zickus, Copyright (C) 2010 Red Hat, Inc.
 *
 * this code detects hard lockups: incidents in where on a CPU
 * the kernel does not respond to anything except NMI.
 *
 * Note: Most of this code is borrowed heavily from softlockup.c,
 * so thanks to Ingo for the initial implementation.
 * Some chunks also taken from arch/x86/kernel/apic/nmi.c, thanks
 * to those contributors as well.
 */

#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 <linux/sysctl.h>

#include <asm/irq_regs.h>
#include <linux/perf_event.h>

int watchdog_enabled;
int __read_mostly softlockup_thresh = 60;

static DEFINE_PER_CPU(unsigned long, watchdog_touch_ts);
static DEFINE_PER_CPU(bool, watchdog_nmi_touch);
static DEFINE_PER_CPU(struct task_struct *, softlockup_watchdog);
static DEFINE_PER_CPU(struct hrtimer, watchdog_hrtimer);
static DEFINE_PER_CPU(bool, softlockup_touch_sync);
static DEFINE_PER_CPU(bool, hard_watchdog_warn);
static DEFINE_PER_CPU(bool, soft_watchdog_warn);
#ifdef CONFIG_PERF_EVENTS_NMI
static DEFINE_PER_CPU(unsigned long, hrtimer_interrupts);
static DEFINE_PER_CPU(unsigned long, hrtimer_interrupts_saved);
static DEFINE_PER_CPU(struct perf_event *, watchdog_ev);
#endif

static int __read_mostly did_panic;
static int __initdata no_watchdog;


/* boot commands */
/*
 * Should we panic when a soft-lockup or hard-lockup occurs:
 */
#ifdef CONFIG_PERF_EVENTS_NMI
static int hardlockup_panic;

static int __init hardlockup_panic_setup(char *str)
{
	if (!strncmp(str, "panic", 5))
		hardlockup_panic = 1;
	return 1;
}
__setup("nmi_watchdog=", hardlockup_panic_setup);
#endif

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 __init nowatchdog_setup(char *str)
{
	no_watchdog = 1;
	return 1;
}
__setup("nowatchdog", nowatchdog_setup);

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


/*
 * 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 unsigned long get_sample_period(void)
{
	/*
	 * convert softlockup_thresh from seconds to ns
	 * the divide by 5 is to give hrtimer 5 chances to
	 * increment before the hardlockup detector generates
	 * a warning
	 */
	return softlockup_thresh / 5 * NSEC_PER_SEC;
}

/* Commands for resetting the watchdog */
static void __touch_watchdog(void)
{
	int this_cpu = raw_smp_processor_id();

	__get_cpu_var(watchdog_touch_ts) = get_timestamp(this_cpu);
}

void touch_softlockup_watchdog(void)
{
	__get_cpu_var(watchdog_touch_ts) = 0;
}
EXPORT_SYMBOL(touch_softlockup_watchdog);

void touch_all_softlockup_watchdogs(void)
{
	int cpu;

	/*
	 * this is done lockless
	 * do we care if a 0 races with a timestamp?
	 * all it means is the softlock check starts one cycle later
	 */
	for_each_online_cpu(cpu)
		per_cpu(watchdog_touch_ts, cpu) = 0;
}

void touch_nmi_watchdog(void)
{
	__get_cpu_var(watchdog_nmi_touch) = true;
	touch_softlockup_watchdog();
}
EXPORT_SYMBOL(touch_nmi_watchdog);

void touch_softlockup_watchdog_sync(void)
{
	__raw_get_cpu_var(softlockup_touch_sync) = true;
	__raw_get_cpu_var(watchdog_touch_ts) = 0;
}

#ifdef CONFIG_PERF_EVENTS_NMI
/* watchdog detector functions */
static int is_hardlockup(int cpu)
{
	unsigned long hrint = per_cpu(hrtimer_interrupts, cpu);

	if (per_cpu(hrtimer_interrupts_saved, cpu) == hrint)
		return 1;

	per_cpu(hrtimer_interrupts_saved, cpu) = hrint;
	return 0;
}
#endif

static int is_softlockup(unsigned long touch_ts, int cpu)
{
	unsigned long now = get_timestamp(cpu);

	/* Warn about unreasonable delays: */
	if (time_after(now, touch_ts + softlockup_thresh))
		return now - touch_ts;

	return 0;
}

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

	return NOTIFY_DONE;
}

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

#ifdef CONFIG_PERF_EVENTS_NMI
static struct perf_event_attr wd_hw_attr = {
	.type		= PERF_TYPE_HARDWARE,
	.config		= PERF_COUNT_HW_CPU_CYCLES,
	.size		= sizeof(struct perf_event_attr),
	.pinned		= 1,
	.disabled	= 1,
};

/* Callback function for perf event subsystem */
void watchdog_overflow_callback(struct perf_event *event, int nmi,
		 struct perf_sample_data *data,
		 struct pt_regs *regs)
{
	int this_cpu = smp_processor_id();

	if (__get_cpu_var(watchdog_nmi_touch) == true) {
		__get_cpu_var(watchdog_nmi_touch) = false;
		return;
	}

	/* check for a hardlockup
	 * This is done by making sure our timer interrupt
	 * is incrementing.  The timer interrupt should have
	 * fired multiple times before we overflow'd.  If it hasn't
	 * then this is a good indication the cpu is stuck
	 */
	if (is_hardlockup(this_cpu)) {
		/* only print hardlockups once */
		if (__get_cpu_var(hard_watchdog_warn) == true)
			return;

		if (hardlockup_panic)
			panic("Watchdog detected hard LOCKUP on cpu %d", this_cpu);
		else
			WARN(1, "Watchdog detected hard LOCKUP on cpu %d", this_cpu);

		__get_cpu_var(hard_watchdog_warn) = true;
		return;
	}

	__get_cpu_var(hard_watchdog_warn) = false;
	return;
}
static void watchdog_interrupt_count(void)
{
	__get_cpu_var(hrtimer_interrupts)++;
}
#else
static inline void watchdog_interrupt_count(void) { return; }
#endif /* CONFIG_PERF_EVENTS_NMI */

/* watchdog kicker functions */
static enum hrtimer_restart watchdog_timer_fn(struct hrtimer *hrtimer)
{
	int this_cpu = smp_processor_id();
	unsigned long touch_ts = __get_cpu_var(watchdog_touch_ts);
	struct pt_regs *regs = get_irq_regs();
	int duration;

	/* kick the hardlockup detector */
	watchdog_interrupt_count();

	/* kick the softlockup detector */
	wake_up_process(__get_cpu_var(softlockup_watchdog));

	/* .. and repeat */
	hrtimer_forward_now(hrtimer, ns_to_ktime(get_sample_period()));

	if (touch_ts == 0) {
		if (unlikely(per_cpu(softlockup_touch_sync, this_cpu))) {
			/*
			 * If the time stamp was touched atomically
			 * make sure the scheduler tick is up to date.
			 */
			per_cpu(softlockup_touch_sync, this_cpu) = false;
			sched_clock_tick();
		}
		__touch_watchdog();
		return HRTIMER_RESTART;
	}

	/* check for a softlockup
	 * This is done by making sure a high priority task is
	 * being scheduled.  The task touches the watchdog to
	 * indicate it is getting cpu time.  If it hasn't then
	 * this is a good indication some task is hogging the cpu
	 */
	duration = is_softlockup(touch_ts, this_cpu);
	if (unlikely(duration)) {
		/* only warn once */
		if (__get_cpu_var(soft_watchdog_warn) == true)
			return HRTIMER_RESTART;

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

		if (softlockup_panic)
			panic("softlockup: hung tasks");
		__get_cpu_var(soft_watchdog_warn) = true;
	} else
		__get_cpu_var(soft_watchdog_warn) = false;

	return HRTIMER_RESTART;
}


/*
 * The watchdog thread - touches the timestamp.
 */
static int watchdog(void *__bind_cpu)
{
	struct sched_param param = { .sched_priority = MAX_RT_PRIO-1 };
	struct hrtimer *hrtimer = &per_cpu(watchdog_hrtimer, (unsigned long)__bind_cpu);

	sched_setscheduler(current, SCHED_FIFO, &param);

	/* initialize timestamp */
	__touch_watchdog();

	/* kick off the timer for the hardlockup detector */
	/* done here because hrtimer_start can only pin to smp_processor_id() */
	hrtimer_start(hrtimer, ns_to_ktime(get_sample_period()),
		      HRTIMER_MODE_REL_PINNED);

	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_watchdog();
		schedule();

		if (kthread_should_stop())
			break;

		set_current_state(TASK_INTERRUPTIBLE);
	}
	__set_current_state(TASK_RUNNING);

	return 0;
}


#ifdef CONFIG_PERF_EVENTS_NMI
static int watchdog_nmi_enable(int cpu)
{
	struct perf_event_attr *wd_attr;
	struct perf_event *event = per_cpu(watchdog_ev, cpu);

	/* is it already setup and enabled? */
	if (event && event->state > PERF_EVENT_STATE_OFF)
		goto out;

	/* it is setup but not enabled */
	if (event != NULL)
		goto out_enable;

	/* Try to register using hardware perf events */
	wd_attr = &wd_hw_attr;
	wd_attr->sample_period = hw_nmi_get_sample_period();
	event = perf_event_create_kernel_counter(wd_attr, cpu, -1, watchdog_overflow_callback);
	if (!IS_ERR(event)) {
		printk(KERN_INFO "NMI watchdog enabled, takes one hw-pmu counter.\n");
		goto out_save;
	}

	printk(KERN_ERR "NMI watchdog failed to create perf event on cpu%i: %p\n", cpu, event);
	return -1;

	/* success path */
out_save:
	per_cpu(watchdog_ev, cpu) = event;
out_enable:
	perf_event_enable(per_cpu(watchdog_ev, cpu));
out:
	return 0;
}

static void watchdog_nmi_disable(int cpu)
{
	struct perf_event *event = per_cpu(watchdog_ev, cpu);

	if (event) {
		perf_event_disable(event);
		per_cpu(watchdog_ev, cpu) = NULL;

		/* should be in cleanup, but blocks oprofile */
		perf_event_release_kernel(event);
	}
	return;
}
#else
static int watchdog_nmi_enable(int cpu) { return 0; }
static void watchdog_nmi_disable(int cpu) { return; }
#endif /* CONFIG_PERF_EVENTS_NMI */

/* prepare/enable/disable routines */
static int watchdog_prepare_cpu(int cpu)
{
	struct hrtimer *hrtimer = &per_cpu(watchdog_hrtimer, cpu);

	WARN_ON(per_cpu(softlockup_watchdog, cpu));
	hrtimer_init(hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
	hrtimer->function = watchdog_timer_fn;

	return 0;
}

static int watchdog_enable(int cpu)
{
	struct task_struct *p = per_cpu(softlockup_watchdog, cpu);

	/* enable the perf event */
	if (watchdog_nmi_enable(cpu) != 0)
		return -1;

	/* create the watchdog thread */
	if (!p) {
		p = kthread_create(watchdog, (void *)(unsigned long)cpu, "watchdog/%d", cpu);
		if (IS_ERR(p)) {
			printk(KERN_ERR "softlockup watchdog for %i failed\n", cpu);
			return -1;
		}
		kthread_bind(p, cpu);
		per_cpu(watchdog_touch_ts, cpu) = 0;
		per_cpu(softlockup_watchdog, cpu) = p;
		wake_up_process(p);
	}

	return 0;
}

static void watchdog_disable(int cpu)
{
	struct task_struct *p = per_cpu(softlockup_watchdog, cpu);
	struct hrtimer *hrtimer = &per_cpu(watchdog_hrtimer, cpu);

	/*
	 * cancel the timer first to stop incrementing the stats
	 * and waking up the kthread
	 */
	hrtimer_cancel(hrtimer);

	/* disable the perf event */
	watchdog_nmi_disable(cpu);

	/* stop the watchdog thread */
	if (p) {
		per_cpu(softlockup_watchdog, cpu) = NULL;
		kthread_stop(p);
	}

	/* if any cpu succeeds, watchdog is considered enabled for the system */
	watchdog_enabled = 1;
}

static void watchdog_enable_all_cpus(void)
{
	int cpu;
	int result;

	for_each_online_cpu(cpu)
		result += watchdog_enable(cpu);

	if (result)
		printk(KERN_ERR "watchdog: failed to be enabled on some cpus\n");

}

static void watchdog_disable_all_cpus(void)
{
	int cpu;

	for_each_online_cpu(cpu)
		watchdog_disable(cpu);

	/* if all watchdogs are disabled, then they are disabled for the system */
	watchdog_enabled = 0;
}


/* sysctl functions */
#ifdef CONFIG_SYSCTL
/*
 * proc handler for /proc/sys/kernel/nmi_watchdog
 */

int proc_dowatchdog_enabled(struct ctl_table *table, int write,
		     void __user *buffer, size_t *length, loff_t *ppos)
{
	proc_dointvec(table, write, buffer, length, ppos);

	if (watchdog_enabled)
		watchdog_enable_all_cpus();
	else
		watchdog_disable_all_cpus();
	return 0;
}

int proc_dowatchdog_thresh(struct ctl_table *table, int write,
			     void __user *buffer,
			     size_t *lenp, loff_t *ppos)
{
	return proc_dointvec_minmax(table, write, buffer, lenp, ppos);
}
#endif /* CONFIG_SYSCTL */


/*
 * 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;

	switch (action) {
	case CPU_UP_PREPARE:
	case CPU_UP_PREPARE_FROZEN:
		if (watchdog_prepare_cpu(hotcpu))
			return NOTIFY_BAD;
		break;
	case CPU_ONLINE:
	case CPU_ONLINE_FROZEN:
		if (watchdog_enable(hotcpu))
			return NOTIFY_BAD;
		break;
#ifdef CONFIG_HOTPLUG_CPU
	case CPU_UP_CANCELED:
	case CPU_UP_CANCELED_FROZEN:
		watchdog_disable(hotcpu);
		break;
	case CPU_DEAD:
	case CPU_DEAD_FROZEN:
		watchdog_disable(hotcpu);
		break;
#endif /* CONFIG_HOTPLUG_CPU */
	}
	return NOTIFY_OK;
}

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

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

	if (no_watchdog)
		return 0;

	err = cpu_callback(&cpu_nfb, CPU_UP_PREPARE, cpu);
	WARN_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);

	return 0;
}
early_initcall(spawn_watchdog_task);
Commit	Line	Data
58687acb DZ	1	/*
	2	* Detect hard and soft lockups on a system
	3	*
	4	* started by Don Zickus, Copyright (C) 2010 Red Hat, Inc.
	5	*
	6	* this code detects hard lockups: incidents in where on a CPU
	7	* the kernel does not respond to anything except NMI.
	8	*
	9	* Note: Most of this code is borrowed heavily from softlockup.c,
	10	* so thanks to Ingo for the initial implementation.
	11	* Some chunks also taken from arch/x86/kernel/apic/nmi.c, thanks
	12	* to those contributors as well.
	13	*/
	14
	15	#include <linux/mm.h>
	16	#include <linux/cpu.h>
	17	#include <linux/nmi.h>
	18	#include <linux/init.h>
	19	#include <linux/delay.h>
	20	#include <linux/freezer.h>
	21	#include <linux/kthread.h>
	22	#include <linux/lockdep.h>
	23	#include <linux/notifier.h>
	24	#include <linux/module.h>
	25	#include <linux/sysctl.h>
	26
	27	#include <asm/irq_regs.h>
	28	#include <linux/perf_event.h>
	29
	30	int watchdog_enabled;
	31	int __read_mostly softlockup_thresh = 60;
	32
	33	static DEFINE_PER_CPU(unsigned long, watchdog_touch_ts);
d7c54733	34	static DEFINE_PER_CPU(bool, watchdog_nmi_touch);
58687acb DZ	35	static DEFINE_PER_CPU(struct task_struct *, softlockup_watchdog);
	36	static DEFINE_PER_CPU(struct hrtimer, watchdog_hrtimer);
	37	static DEFINE_PER_CPU(bool, softlockup_touch_sync);
	38	static DEFINE_PER_CPU(bool, hard_watchdog_warn);
	39	static DEFINE_PER_CPU(bool, soft_watchdog_warn);
	40	#ifdef CONFIG_PERF_EVENTS_NMI
	41	static DEFINE_PER_CPU(unsigned long, hrtimer_interrupts);
	42	static DEFINE_PER_CPU(unsigned long, hrtimer_interrupts_saved);
	43	static DEFINE_PER_CPU(struct perf_event *, watchdog_ev);
	44	#endif
	45
	46	static int __read_mostly did_panic;
	47	static int __initdata no_watchdog;
	48
	49
	50	/* boot commands */
	51	/*
	52	* Should we panic when a soft-lockup or hard-lockup occurs:
	53	*/
	54	#ifdef CONFIG_PERF_EVENTS_NMI
	55	static int hardlockup_panic;
	56
	57	static int __init hardlockup_panic_setup(char *str)
	58	{
	59	if (!strncmp(str, "panic", 5))
	60	hardlockup_panic = 1;
	61	return 1;
	62	}
	63	__setup("nmi_watchdog=", hardlockup_panic_setup);
	64	#endif
	65
	66	unsigned int __read_mostly softlockup_panic =
	67	CONFIG_BOOTPARAM_SOFTLOCKUP_PANIC_VALUE;
	68
	69	static int __init softlockup_panic_setup(char *str)
	70	{
	71	softlockup_panic = simple_strtoul(str, NULL, 0);
	72
	73	return 1;
	74	}
	75	__setup("softlockup_panic=", softlockup_panic_setup);
	76
	77	static int __init nowatchdog_setup(char *str)
	78	{
	79	no_watchdog = 1;
	80	return 1;
	81	}
	82	__setup("nowatchdog", nowatchdog_setup);
	83
	84	/* deprecated */
	85	static int __init nosoftlockup_setup(char *str)
	86	{
	87	no_watchdog = 1;
	88	return 1;
	89	}
	90	__setup("nosoftlockup", nosoftlockup_setup);
	91	/* */
	92
	93
	94	/*
	95	* Returns seconds, approximately. We don't need nanosecond
	96	* resolution, and we don't need to waste time with a big divide when
	97	* 2^30ns == 1.074s.
	98	*/
99	static unsigned long get_timestamp(int this_cpu)
100	{
101	return cpu_clock(this_cpu) >> 30LL; /* 2^30 ~= 10^9 */
102	}
103
104	static unsigned long get_sample_period(void)
105	{
106	/*
107	* convert softlockup_thresh from seconds to ns
108	* the divide by 5 is to give hrtimer 5 chances to
109	* increment before the hardlockup detector generates
110	* a warning
111	*/
112	return softlockup_thresh / 5 * NSEC_PER_SEC;
113	}
114
115	/* Commands for resetting the watchdog */
116	static void __touch_watchdog(void)
117	{
118	int this_cpu = raw_smp_processor_id();
119
120	__get_cpu_var(watchdog_touch_ts) = get_timestamp(this_cpu);
121	}
122
332fbdbc	123	void touch_softlockup_watchdog(void)
58687acb DZ	124	{
	125	__get_cpu_var(watchdog_touch_ts) = 0;
	126	}
0167c781	127	EXPORT_SYMBOL(touch_softlockup_watchdog);
58687acb	128
332fbdbc	129	void touch_all_softlockup_watchdogs(void)
58687acb DZ	130	{
	131	int cpu;
	132
	133	/*
	134	* this is done lockless
	135	* do we care if a 0 races with a timestamp?
	136	* all it means is the softlock check starts one cycle later
	137	*/
	138	for_each_online_cpu(cpu)
	139	per_cpu(watchdog_touch_ts, cpu) = 0;
	140	}
	141
	142	void touch_nmi_watchdog(void)
	143	{
d7c54733	144	__get_cpu_var(watchdog_nmi_touch) = true;
332fbdbc	145	touch_softlockup_watchdog();
58687acb DZ	146	}
	147	EXPORT_SYMBOL(touch_nmi_watchdog);
	148
58687acb DZ	149	void touch_softlockup_watchdog_sync(void)
	150	{
	151	__raw_get_cpu_var(softlockup_touch_sync) = true;
	152	__raw_get_cpu_var(watchdog_touch_ts) = 0;
	153	}
	154
58687acb DZ	155	#ifdef CONFIG_PERF_EVENTS_NMI
	156	/* watchdog detector functions */
	157	static int is_hardlockup(int cpu)
	158	{
	159	unsigned long hrint = per_cpu(hrtimer_interrupts, cpu);
	160
	161	if (per_cpu(hrtimer_interrupts_saved, cpu) == hrint)
	162	return 1;
	163
	164	per_cpu(hrtimer_interrupts_saved, cpu) = hrint;
	165	return 0;
	166	}
	167	#endif
	168
	169	static int is_softlockup(unsigned long touch_ts, int cpu)
	170	{
	171	unsigned long now = get_timestamp(cpu);
	172
	173	/* Warn about unreasonable delays: */
	174	if (time_after(now, touch_ts + softlockup_thresh))
	175	return now - touch_ts;
	176
	177	return 0;
	178	}
	179
	180	static int
	181	watchdog_panic(struct notifier_block this, unsigned long event, void ptr)
	182	{
	183	did_panic = 1;
	184
	185	return NOTIFY_DONE;
	186	}
	187
	188	static struct notifier_block panic_block = {
	189	.notifier_call = watchdog_panic,
	190	};
	191
	192	#ifdef CONFIG_PERF_EVENTS_NMI
	193	static struct perf_event_attr wd_hw_attr = {
	194	.type = PERF_TYPE_HARDWARE,
	195	.config = PERF_COUNT_HW_CPU_CYCLES,
	196	.size = sizeof(struct perf_event_attr),
	197	.pinned = 1,
	198	.disabled = 1,
	199	};
	200
	201	/* Callback function for perf event subsystem */
	202	void watchdog_overflow_callback(struct perf_event *event, int nmi,
	203	struct perf_sample_data *data,
	204	struct pt_regs *regs)
	205	{
	206	int this_cpu = smp_processor_id();
58687acb	207
d7c54733 DZ	208	if (__get_cpu_var(watchdog_nmi_touch) == true) {
d7c54733 DZ	209	__get_cpu_var(watchdog_nmi_touch) = false;
58687acb DZ	210	return;
	211	}
	212
	213	/* check for a hardlockup
	214	* This is done by making sure our timer interrupt
	215	* is incrementing. The timer interrupt should have
	216	* fired multiple times before we overflow'd. If it hasn't
	217	* then this is a good indication the cpu is stuck
	218	*/
	219	if (is_hardlockup(this_cpu)) {
	220	/* only print hardlockups once */
	221	if (__get_cpu_var(hard_watchdog_warn) == true)
	222	return;
	223
	224	if (hardlockup_panic)
	225	panic("Watchdog detected hard LOCKUP on cpu %d", this_cpu);
	226	else
	227	WARN(1, "Watchdog detected hard LOCKUP on cpu %d", this_cpu);
	228
	229	__get_cpu_var(hard_watchdog_warn) = true;
	230	return;
	231	}
	232
	233	__get_cpu_var(hard_watchdog_warn) = false;
	234	return;
	235	}
	236	static void watchdog_interrupt_count(void)
	237	{
	238	__get_cpu_var(hrtimer_interrupts)++;
	239	}
	240	#else
	241	static inline void watchdog_interrupt_count(void) { return; }
	242	#endif /* CONFIG_PERF_EVENTS_NMI */
	243
	244	/* watchdog kicker functions */
	245	static enum hrtimer_restart watchdog_timer_fn(struct hrtimer *hrtimer)
	246	{
	247	int this_cpu = smp_processor_id();
	248	unsigned long touch_ts = __get_cpu_var(watchdog_touch_ts);
	249	struct pt_regs *regs = get_irq_regs();
	250	int duration;
	251
	252	/* kick the hardlockup detector */
	253	watchdog_interrupt_count();
	254
	255	/* kick the softlockup detector */
	256	wake_up_process(__get_cpu_var(softlockup_watchdog));
	257
	258	/* .. and repeat */
	259	hrtimer_forward_now(hrtimer, ns_to_ktime(get_sample_period()));
	260
	261	if (touch_ts == 0) {
	262	if (unlikely(per_cpu(softlockup_touch_sync, this_cpu))) {
	263	/*
	264	* If the time stamp was touched atomically
	265	* make sure the scheduler tick is up to date.
	266	*/
	267	per_cpu(softlockup_touch_sync, this_cpu) = false;
	268	sched_clock_tick();
	269	}
	270	__touch_watchdog();
	271	return HRTIMER_RESTART;
	272	}
	273
274	/* check for a softlockup
275	* This is done by making sure a high priority task is
276	* being scheduled. The task touches the watchdog to
277	* indicate it is getting cpu time. If it hasn't then
278	* this is a good indication some task is hogging the cpu
279	*/
280	duration = is_softlockup(touch_ts, this_cpu);
281	if (unlikely(duration)) {
282	/* only warn once */
283	if (__get_cpu_var(soft_watchdog_warn) == true)
284	return HRTIMER_RESTART;
285
286	printk(KERN_ERR "BUG: soft lockup - CPU#%d stuck for %us! [%s:%d]\n",
287	this_cpu, duration,
288	current->comm, task_pid_nr(current));
289	print_modules();
290	print_irqtrace_events(current);
291	if (regs)
292	show_regs(regs);
293	else
294	dump_stack();
295
296	if (softlockup_panic)
297	panic("softlockup: hung tasks");
298	__get_cpu_var(soft_watchdog_warn) = true;
299	} else
300	__get_cpu_var(soft_watchdog_warn) = false;
301
302	return HRTIMER_RESTART;
303	}
304
305
306	/*
307	* The watchdog thread - touches the timestamp.
308	*/
309	static int watchdog(void *__bind_cpu)
310	{
311	struct sched_param param = { .sched_priority = MAX_RT_PRIO-1 };
312	struct hrtimer *hrtimer = &per_cpu(watchdog_hrtimer, (unsigned long)__bind_cpu);
313
314	sched_setscheduler(current, SCHED_FIFO, &param);
315
316	/* initialize timestamp */
317	__touch_watchdog();
318
319	/* kick off the timer for the hardlockup detector */
320	/* done here because hrtimer_start can only pin to smp_processor_id() */
321	hrtimer_start(hrtimer, ns_to_ktime(get_sample_period()),
322	HRTIMER_MODE_REL_PINNED);
323
324	set_current_state(TASK_INTERRUPTIBLE);
325	/*
326	* Run briefly once per second to reset the softlockup timestamp.
327	* If this gets delayed for more than 60 seconds then the
328	* debug-printout triggers in softlockup_tick().
329	*/
330	while (!kthread_should_stop()) {
331	__touch_watchdog();
332	schedule();
333
334	if (kthread_should_stop())
335	break;
336
337	set_current_state(TASK_INTERRUPTIBLE);
338	}
339	__set_current_state(TASK_RUNNING);
340
341	return 0;
342	}
343
344
345	#ifdef CONFIG_PERF_EVENTS_NMI
346	static int watchdog_nmi_enable(int cpu)
347	{
348	struct perf_event_attr *wd_attr;
349	struct perf_event *event = per_cpu(watchdog_ev, cpu);
350
351	/* is it already setup and enabled? */
352	if (event && event->state > PERF_EVENT_STATE_OFF)
353	goto out;
354
355	/* it is setup but not enabled */
356	if (event != NULL)
357	goto out_enable;
358
359	/* Try to register using hardware perf events */
360	wd_attr = &wd_hw_attr;
361	wd_attr->sample_period = hw_nmi_get_sample_period();
362	event = perf_event_create_kernel_counter(wd_attr, cpu, -1, watchdog_overflow_callback);
363	if (!IS_ERR(event)) {
364	printk(KERN_INFO "NMI watchdog enabled, takes one hw-pmu counter.\n");
365	goto out_save;
366	}
367
368	printk(KERN_ERR "NMI watchdog failed to create perf event on cpu%i: %p\n", cpu, event);
369	return -1;
370
371	/* success path */
372	out_save:
373	per_cpu(watchdog_ev, cpu) = event;
374	out_enable:
375	perf_event_enable(per_cpu(watchdog_ev, cpu));
376	out:
377	return 0;
378	}
379
380	static void watchdog_nmi_disable(int cpu)
381	{
382	struct perf_event *event = per_cpu(watchdog_ev, cpu);
383
384	if (event) {
385	perf_event_disable(event);
386	per_cpu(watchdog_ev, cpu) = NULL;
387
388	/* should be in cleanup, but blocks oprofile */
389	perf_event_release_kernel(event);
390	}
391	return;
392	}
393	#else
394	static int watchdog_nmi_enable(int cpu) { return 0; }
395	static void watchdog_nmi_disable(int cpu) { return; }
396	#endif /* CONFIG_PERF_EVENTS_NMI */
397
398	/* prepare/enable/disable routines */
399	static int watchdog_prepare_cpu(int cpu)
400	{
401	struct hrtimer *hrtimer = &per_cpu(watchdog_hrtimer, cpu);
402
403	WARN_ON(per_cpu(softlockup_watchdog, cpu));
404	hrtimer_init(hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
405	hrtimer->function = watchdog_timer_fn;
406
407	return 0;
408	}
409
410	static int watchdog_enable(int cpu)
411	{
412	struct task_struct *p = per_cpu(softlockup_watchdog, cpu);
413
414	/* enable the perf event */
415	if (watchdog_nmi_enable(cpu) != 0)
416	return -1;
417
418	/* create the watchdog thread */
419	if (!p) {
420	p = kthread_create(watchdog, (void *)(unsigned long)cpu, "watchdog/%d", cpu);
421	if (IS_ERR(p)) {
422	printk(KERN_ERR "softlockup watchdog for %i failed\n", cpu);
423	return -1;
424	}
425	kthread_bind(p, cpu);
426	per_cpu(watchdog_touch_ts, cpu) = 0;
427	per_cpu(softlockup_watchdog, cpu) = p;
428	wake_up_process(p);
429	}
430
431	return 0;
432	}
433
434	static void watchdog_disable(int cpu)
435	{
436	struct task_struct *p = per_cpu(softlockup_watchdog, cpu);
437	struct hrtimer *hrtimer = &per_cpu(watchdog_hrtimer, cpu);
438
439	/*
440	* cancel the timer first to stop incrementing the stats
441	* and waking up the kthread
442	*/
443	hrtimer_cancel(hrtimer);
444
445	/* disable the perf event */
446	watchdog_nmi_disable(cpu);
447
448	/* stop the watchdog thread */
449	if (p) {
450	per_cpu(softlockup_watchdog, cpu) = NULL;
451	kthread_stop(p);
452	}
453
454	/* if any cpu succeeds, watchdog is considered enabled for the system */
455	watchdog_enabled = 1;
456	}
457
458	static void watchdog_enable_all_cpus(void)
459	{
460	int cpu;
461	int result;
462
463	for_each_online_cpu(cpu)
464	result += watchdog_enable(cpu);
465
466	if (result)
467	printk(KERN_ERR "watchdog: failed to be enabled on some cpus\n");
468
469	}
470
471	static void watchdog_disable_all_cpus(void)
472	{
473	int cpu;
474
475	for_each_online_cpu(cpu)
476	watchdog_disable(cpu);
477
478	/* if all watchdogs are disabled, then they are disabled for the system */
479	watchdog_enabled = 0;
480	}
481
482
483	/* sysctl functions */
484	#ifdef CONFIG_SYSCTL
485	/*
486	* proc handler for /proc/sys/kernel/nmi_watchdog
487	*/
488
489	int proc_dowatchdog_enabled(struct ctl_table *table, int write,
490	void __user buffer, size_t length, loff_t *ppos)
491	{
492	proc_dointvec(table, write, buffer, length, ppos);
493
494	if (watchdog_enabled)
495	watchdog_enable_all_cpus();
496	else
497	watchdog_disable_all_cpus();
498	return 0;
499	}
500
501	int proc_dowatchdog_thresh(struct ctl_table *table, int write,
502	void __user *buffer,
503	size_t lenp, loff_t ppos)
504	{
505	return proc_dointvec_minmax(table, write, buffer, lenp, ppos);
506	}
58687acb DZ	507	#endif /* CONFIG_SYSCTL */
	508
	509
	510	/*
	511	* Create/destroy watchdog threads as CPUs come and go:
	512	*/
	513	static int __cpuinit
	514	cpu_callback(struct notifier_block nfb, unsigned long action, void hcpu)
	515	{
	516	int hotcpu = (unsigned long)hcpu;
	517
	518	switch (action) {
	519	case CPU_UP_PREPARE:
	520	case CPU_UP_PREPARE_FROZEN:
	521	if (watchdog_prepare_cpu(hotcpu))
	522	return NOTIFY_BAD;
	523	break;
	524	case CPU_ONLINE:
	525	case CPU_ONLINE_FROZEN:
	526	if (watchdog_enable(hotcpu))
	527	return NOTIFY_BAD;
	528	break;
	529	#ifdef CONFIG_HOTPLUG_CPU
	530	case CPU_UP_CANCELED:
	531	case CPU_UP_CANCELED_FROZEN:
	532	watchdog_disable(hotcpu);
	533	break;
	534	case CPU_DEAD:
	535	case CPU_DEAD_FROZEN:
	536	watchdog_disable(hotcpu);
	537	break;
	538	#endif /* CONFIG_HOTPLUG_CPU */
	539	}
	540	return NOTIFY_OK;
	541	}
	542
	543	static struct notifier_block __cpuinitdata cpu_nfb = {
	544	.notifier_call = cpu_callback
	545	};
	546
	547	static int __init spawn_watchdog_task(void)
	548	{
	549	void cpu = (void )(long)smp_processor_id();
	550	int err;
	551
	552	if (no_watchdog)
	553	return 0;
	554
	555	err = cpu_callback(&cpu_nfb, CPU_UP_PREPARE, cpu);
	556	WARN_ON(err == NOTIFY_BAD);
	557
	558	cpu_callback(&cpu_nfb, CPU_ONLINE, cpu);
	559	register_cpu_notifier(&cpu_nfb);
	560
	561	atomic_notifier_chain_register(&panic_notifier_list, &panic_block);
	562
	563	return 0;
	564	}
	565	early_initcall(spawn_watchdog_task);