kernel/softlockup.c - kernel/msm - Gitiles

 /*
  * 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;
 unsigned long __read_mostly softlockup_thresh = 60;

 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;

 	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 || !per_cpu(watchdog_task, this_cpu)) {
 		return;
 	}

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

 	now = get_timestamp(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);
 }

 /*
  * 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();
 }

 /*
  * 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)
 			break;
 		if (t->state & TASK_UNINTERRUPTIBLE)
 			check_hung_task(t, now);
 	} while_each_thread(g, t);

 	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();

 	/*
 	 * 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();
 		msleep_interruptible(10000);

 		if (this_cpu != check_cpu)
 			continue;

 		if (sysctl_hung_task_timeout_secs)
 			check_hung_uninterruptible_tasks(this_cpu);
 	}

 	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_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_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_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);
 }
	/*
	* 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;
	unsigned long __read_mostly softlockup_thresh = 60;

	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;

	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 \|\| !per_cpu(watchdog_task, this_cpu)) {
	return;
	}

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

	now = get_timestamp(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);
	}

	/*
	* 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();
	}

	/*
	* 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)
	break;
	if (t->state & TASK_UNINTERRUPTIBLE)
	check_hung_task(t, now);
	} while_each_thread(g, t);

	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();

	/*
	* 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();
	msleep_interruptible(10000);

	if (this_cpu != check_cpu)
	continue;

	if (sysctl_hung_task_timeout_secs)
	check_hung_uninterruptible_tasks(this_cpu);
	}

	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_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_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_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);
	}