kernel/softlockup.c - maze/linux - Git at Google

 /*
  * 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 <linux/sysctl.h>

 #include <asm/irq_regs.h>

 static DEFINE_SPINLOCK(print_lock);

 static DEFINE_PER_CPU(unsigned long, softlockup_touch_ts); /* touch timestamp */
 static DEFINE_PER_CPU(unsigned long, softlockup_print_ts); /* print timestamp */
 static DEFINE_PER_CPU(struct task_struct *, softlockup_watchdog);
 static DEFINE_PER_CPU(bool, softlock_touch_sync);

 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(softlockup_touch_ts) = get_timestamp(this_cpu);
 }

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

 void touch_softlockup_watchdog_sync(void)
 {
 	__raw_get_cpu_var(softlock_touch_sync) = true;
 	__raw_get_cpu_var(softlockup_touch_ts) = 0;
 }

 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(softlockup_touch_ts, cpu) = 0;
 }
 EXPORT_SYMBOL(touch_all_softlockup_watchdogs);

 int proc_dosoftlockup_thresh(struct ctl_table *table, int write,
 			     void __user *buffer,
 			     size_t *lenp, loff_t *ppos)
 {
 	touch_all_softlockup_watchdogs();
 	return proc_dointvec_minmax(table, write, buffer, lenp, ppos);
 }

 /*
  * 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_ts = per_cpu(softlockup_touch_ts, this_cpu);
 	unsigned long print_ts;
 	struct pt_regs *regs = get_irq_regs();
 	unsigned long now;

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

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

 	print_ts = per_cpu(softlockup_print_ts, this_cpu);

 	/* report at most once a second */
 	if (print_ts == touch_ts || 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_ts + softlockup_thresh/2)
 		wake_up_process(per_cpu(softlockup_watchdog, this_cpu));

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

 	per_cpu(softlockup_print_ts, this_cpu) = touch_ts;

 	spin_lock(&print_lock);
 	printk(KERN_ERR "BUG: soft lockup - CPU#%d stuck for %lus! [%s:%d]\n",
 			this_cpu, now - touch_ts,
 			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");
 }

 /*
  * 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 };

 	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;

 		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(softlockup_watchdog, 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(softlockup_touch_ts, hotcpu) = 0;
 		per_cpu(softlockup_watchdog, hotcpu) = p;
 		kthread_bind(p, hotcpu);
 		break;
 	case CPU_ONLINE:
 	case CPU_ONLINE_FROZEN:
 		wake_up_process(per_cpu(softlockup_watchdog, hotcpu));
 		break;
 #ifdef CONFIG_HOTPLUG_CPU
 	case CPU_UP_CANCELED:
 	case CPU_UP_CANCELED_FROZEN:
 		if (!per_cpu(softlockup_watchdog, hotcpu))
 			break;
 		/* Unbind so it can run.  Fall thru. */
 		kthread_bind(per_cpu(softlockup_watchdog, hotcpu),
 			     cpumask_any(cpu_online_mask));
 	case CPU_DEAD:
 	case CPU_DEAD_FROZEN:
 		p = per_cpu(softlockup_watchdog, hotcpu);
 		per_cpu(softlockup_watchdog, 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);
	/*
	* 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 <linux/sysctl.h>

	#include <asm/irq_regs.h>

	static DEFINE_SPINLOCK(print_lock);

	static DEFINE_PER_CPU(unsigned long, softlockup_touch_ts); /* touch timestamp */
	static DEFINE_PER_CPU(unsigned long, softlockup_print_ts); /* print timestamp */
	static DEFINE_PER_CPU(struct task_struct *, softlockup_watchdog);
	static DEFINE_PER_CPU(bool, softlock_touch_sync);

	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(softlockup_touch_ts) = get_timestamp(this_cpu);
	}

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

	void touch_softlockup_watchdog_sync(void)
	{
	__raw_get_cpu_var(softlock_touch_sync) = true;
	__raw_get_cpu_var(softlockup_touch_ts) = 0;
	}

	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(softlockup_touch_ts, cpu) = 0;
	}
	EXPORT_SYMBOL(touch_all_softlockup_watchdogs);

	int proc_dosoftlockup_thresh(struct ctl_table *table, int write,
	void __user *buffer,
	size_t lenp, loff_t ppos)
	{
	touch_all_softlockup_watchdogs();
	return proc_dointvec_minmax(table, write, buffer, lenp, ppos);
	}

	/*
	* 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_ts = per_cpu(softlockup_touch_ts, this_cpu);
	unsigned long print_ts;
	struct pt_regs *regs = get_irq_regs();
	unsigned long now;

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

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

	print_ts = per_cpu(softlockup_print_ts, this_cpu);

	/* report at most once a second */
	if (print_ts == touch_ts \|\| 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_ts + softlockup_thresh/2)
	wake_up_process(per_cpu(softlockup_watchdog, this_cpu));

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

	per_cpu(softlockup_print_ts, this_cpu) = touch_ts;

	spin_lock(&print_lock);
	printk(KERN_ERR "BUG: soft lockup - CPU#%d stuck for %lus! [%s:%d]\n",
	this_cpu, now - touch_ts,
	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");
	}

	/*
	* 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 };

	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;

	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(softlockup_watchdog, 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(softlockup_touch_ts, hotcpu) = 0;
	per_cpu(softlockup_watchdog, hotcpu) = p;
	kthread_bind(p, hotcpu);
	break;
	case CPU_ONLINE:
	case CPU_ONLINE_FROZEN:
	wake_up_process(per_cpu(softlockup_watchdog, hotcpu));
	break;
	#ifdef CONFIG_HOTPLUG_CPU
	case CPU_UP_CANCELED:
	case CPU_UP_CANCELED_FROZEN:
	if (!per_cpu(softlockup_watchdog, hotcpu))
	break;
	/* Unbind so it can run. Fall thru. */
	kthread_bind(per_cpu(softlockup_watchdog, hotcpu),
	cpumask_any(cpu_online_mask));
	case CPU_DEAD:
	case CPU_DEAD_FROZEN:
	p = per_cpu(softlockup_watchdog, hotcpu);
	per_cpu(softlockup_watchdog, 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);