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Commit 1798bc22 authored by Cyrill Gorcunov's avatar Cyrill Gorcunov Committed by Thomas Gleixner
Browse files

x86: nmi_32/64.c - merge down nmi_32.c and nmi_64.c to nmi.c 



Signed-off-by: default avatarCyrill Gorcunov <gorcunov@gmail.com>
Cc: hpa@zytor.com
Cc: mingo@redhat.com
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent fd5cea02

arch/x86/kernel/Makefile

+1 −1
Original line number Diff line number Diff line
@@ -53,7 +53,7 @@ obj-$(CONFIG_X86_32_SMP) += smpcommon.o 
obj-$(CONFIG_X86_64_SMP)	+= tsc_sync.o smpcommon.o

obj-$(CONFIG_X86_TRAMPOLINE)	+= trampoline_$(BITS).o

obj-$(CONFIG_X86_MPPARSE)	+= mpparse.o

obj-$(CONFIG_X86_LOCAL_APIC)	+= apic_$(BITS).o nmi_$(BITS).o

obj-$(CONFIG_X86_LOCAL_APIC)	+= apic_$(BITS).o nmi.o

obj-$(CONFIG_X86_IO_APIC)	+= io_apic_$(BITS).o

obj-$(CONFIG_X86_REBOOTFIXUPS)	+= reboot_fixups_32.o

obj-$(CONFIG_KEXEC)		+= machine_kexec_$(BITS).o

arch/x86/kernel/nmi_32.c→arch/x86/kernel/nmi.c

+64 −37
Original line number Diff line number Diff line
@@ -11,10 +11,11 @@ 
 *  Mikael Pettersson	: PM converted to driver model. Disable/enable API.

 */



#include <linux/nmi.h>

#include <linux/mm.h>

#include <linux/delay.h>

#include <linux/interrupt.h>

#include <linux/module.h>

#include <linux/nmi.h>

#include <linux/sysdev.h>

#include <linux/sysctl.h>

#include <linux/percpu.h>
@@ -22,13 +23,15 @@ 
#include <linux/cpumask.h>

#include <linux/kernel_stat.h>

#include <linux/kdebug.h>

#include <linux/slab.h>



#include <asm/smp.h>

#include <asm/nmi.h>

#include <asm/proto.h>

#include <asm/timer.h>



#include "mach_traps.h"

#include <asm/mce.h>



#include <mach_traps.h>



int unknown_nmi_panic;

int nmi_watchdog_enabled;
@@ -45,19 +48,25 @@ atomic_t nmi_active = ATOMIC_INIT(0); /* oprofile uses this */ 
static int panic_on_timeout;



unsigned int nmi_watchdog = NMI_DEFAULT;

static unsigned int nmi_hz = HZ;



static unsigned int nmi_hz = HZ;

static DEFINE_PER_CPU(short, wd_enabled);



static int endflag __initdata = 0;



static inline unsigned int get_nmi_count(int cpu)

{

#ifdef CONFIG_X86_64

	return cpu_pda(cpu)->__nmi_count;

#else

	return nmi_count(cpu);

#endif

}



static inline int mce_in_progress(void)

{

#if defined(CONFIX_X86_64) && defined(CONFIG_X86_MCE)

	return atomic_read(&mce_entry) > 0;

#endif

	return 0;

}
@@ -67,8 +76,12 @@ static inline int mce_in_progress(void) 
 */

static inline unsigned int get_timer_irqs(int cpu)

{

#ifdef CONFIG_X86_64

	return read_pda(apic_timer_irqs) + read_pda(irq0_irqs);

#else

	return per_cpu(irq_stat, cpu).apic_timer_irqs +

		per_cpu(irq_stat, cpu).irq0_irqs;

#endif

}



/* Run after command line and cpu_init init, but before all other checks */
@@ -76,26 +89,33 @@ void nmi_watchdog_default(void) 
{

	if (nmi_watchdog != NMI_DEFAULT)

		return;

#ifdef CONFIG_X86_64

	nmi_watchdog = NMI_NONE;

#else

	if (lapic_watchdog_ok())

		nmi_watchdog = NMI_LOCAL_APIC;

	else

		nmi_watchdog = NMI_IO_APIC;

#endif

}



#ifdef CONFIG_SMP

/* The performance counters used by NMI_LOCAL_APIC don't trigger when

/*

 * The performance counters used by NMI_LOCAL_APIC don't trigger when

 * the CPU is idle. To make sure the NMI watchdog really ticks on all

 * CPUs during the test make them busy.

 */

static __init void nmi_cpu_busy(void *data)

{

	local_irq_enable_in_hardirq();

	/* Intentionally don't use cpu_relax here. This is

	   to make sure that the performance counter really ticks,

	   even if there is a simulator or similar that catches the

	   pause instruction. On a real HT machine this is fine because

	   all other CPUs are busy with "useless" delay loops and don't

	   care if they get somewhat less cycles. */

	/*

	 * Intentionally don't use cpu_relax here. This is

	 * to make sure that the performance counter really ticks,

	 * even if there is a simulator or similar that catches the

	 * pause instruction. On a real HT machine this is fine because

	 * all other CPUs are busy with "useless" delay loops and don't

	 * care if they get somewhat less cycles.

	 */

	while (endflag == 0)

		mb();

}
@@ -106,7 +126,7 @@ int __init check_nmi_watchdog(void) 
	unsigned int *prev_nmi_count;

	int cpu;



	if ((nmi_watchdog == NMI_NONE) || (nmi_watchdog == NMI_DISABLED))

	if (nmi_watchdog == NMI_NONE || nmi_watchdog == NMI_DISABLED)

		return 0;



	if (!atomic_read(&nmi_active))
@@ -126,7 +146,7 @@ int __init check_nmi_watchdog(void) 
	for_each_possible_cpu(cpu)

		prev_nmi_count[cpu] = get_nmi_count(cpu);

	local_irq_enable();

	mdelay((20*1000)/nmi_hz); // wait 20 ticks

	mdelay((20 * 1000) / nmi_hz); /* wait 20 ticks */



	for_each_online_cpu(cpu) {

		if (!per_cpu(wd_enabled, cpu))
@@ -149,16 +169,20 @@ int __init check_nmi_watchdog(void) 
	}

	printk("OK.\n");



	/* now that we know it works we can reduce NMI frequency to

	   something more reasonable; makes a difference in some configs */

	/*

	 * now that we know it works we can reduce NMI frequency to

	 * something more reasonable; makes a difference in some configs

	 */

	if (nmi_watchdog == NMI_LOCAL_APIC)

		nmi_hz = lapic_adjust_nmi_hz(1);



	kfree(prev_nmi_count);

	return 0;



error:

#ifdef CONFIG_X86_32

	timer_ack = !cpu_has_tsc;



#endif

	return -1;

}
@@ -176,18 +200,17 @@ static int __init setup_nmi_watchdog(char *str) 


	get_option(&str, &nmi);



	if ((nmi >= NMI_INVALID) || (nmi < NMI_NONE))

	if (nmi >= NMI_INVALID || nmi < NMI_NONE)

		return 0;



	nmi_watchdog = nmi;

	return 1;

}



__setup("nmi_watchdog=", setup_nmi_watchdog);





/* Suspend/resume support */



/*

 * Suspend/resume support

 */

#ifdef CONFIG_PM



static int nmi_pm_active; /* nmi_active before suspend */
@@ -211,7 +234,6 @@ static int lapic_nmi_resume(struct sys_device *dev) 
	return 0;

}





static struct sysdev_class nmi_sysclass = {

	.name		= "lapic_nmi",

	.resume		= lapic_nmi_resume,
@@ -227,7 +249,8 @@ static int __init init_lapic_nmi_sysfs(void) 
{

	int error;



	/* should really be a BUG_ON but b/c this is an

	/*

	 * should really be a BUG_ON but b/c this is an

	 * init call, it just doesn't work.  -dcz

	 */

	if (nmi_watchdog != NMI_LOCAL_APIC)
@@ -241,6 +264,7 @@ static int __init init_lapic_nmi_sysfs(void) 
		error = sysdev_register(&device_lapic_nmi);

	return error;

}



/* must come after the local APIC's device_initcall() */

late_initcall(init_lapic_nmi_sysfs);
@@ -281,12 +305,13 @@ void setup_apic_nmi_watchdog(void *unused) 


	/* cheap hack to support suspend/resume */

	/* if cpu0 is not active neither should the other cpus */

	if ((smp_processor_id() != 0) && (atomic_read(&nmi_active) <= 0))

	if (smp_processor_id() != 0 && atomic_read(&nmi_active) <= 0)

		return;



	switch (nmi_watchdog) {

	case NMI_LOCAL_APIC:

		__get_cpu_var(wd_enabled) = 1; /* enable it before to avoid race with handler */

		 /* enable it before to avoid race with handler */

		__get_cpu_var(wd_enabled) = 1;

		if (lapic_watchdog_init(nmi_hz) < 0) {

			__get_cpu_var(wd_enabled) = 0;

			return;
@@ -301,8 +326,8 @@ void setup_apic_nmi_watchdog(void *unused) 
void stop_apic_nmi_watchdog(void *unused)

{

	/* only support LOCAL and IO APICs for now */

	if ((nmi_watchdog != NMI_LOCAL_APIC) &&

	    (nmi_watchdog != NMI_IO_APIC))

	if (nmi_watchdog != NMI_LOCAL_APIC &&

	    nmi_watchdog != NMI_IO_APIC)

		return;

	if (__get_cpu_var(wd_enabled) == 0)

		return;
@@ -323,8 +348,7 @@ void stop_apic_nmi_watchdog(void *unused) 
 * since NMIs don't listen to _any_ locks, we have to be extremely

 * careful not to rely on unsafe variables. The printk might lock

 * up though, so we have to break up any console locks first ...

 * [when there will be more tty-related locks, break them up

 *  here too!]

 * [when there will be more tty-related locks, break them up here too!]

 */



static DEFINE_PER_CPU(unsigned, last_irq_sum);
@@ -357,7 +381,6 @@ EXPORT_SYMBOL(touch_nmi_watchdog); 
notrace __kprobes int

nmi_watchdog_tick(struct pt_regs *regs, unsigned reason)

{



	/*

	 * Since current_thread_info()-> is always on the stack, and we

	 * always switch the stack NMI-atomically, it's safe to use
@@ -413,6 +436,7 @@ nmi_watchdog_tick(struct pt_regs *regs, unsigned reason) 
		__get_cpu_var(last_irq_sum) = sum;

		local_set(&__get_cpu_var(alert_counter), 0);

	}



	/* see if the nmi watchdog went off */

	if (!__get_cpu_var(wd_enabled))

		return rc;
@@ -421,7 +445,8 @@ nmi_watchdog_tick(struct pt_regs *regs, unsigned reason) 
		rc |= lapic_wd_event(nmi_hz);

		break;

	case NMI_IO_APIC:

		/* don't know how to accurately check for this.

		/*

		 * don't know how to accurately check for this.

		 * just assume it was a watchdog timer interrupt

		 * This matches the old behaviour.

		 */
@@ -458,7 +483,8 @@ int proc_nmi_enabled(struct ctl_table *table, int write, struct file *file, 
		return 0;



	if (atomic_read(&nmi_active) < 0 || nmi_watchdog == NMI_DISABLED) {

		printk( KERN_WARNING "NMI watchdog is permanently disabled\n");

		printk(KERN_WARNING

			"NMI watchdog is permanently disabled\n");

		return -EIO;

	}
@@ -478,7 +504,7 @@ int proc_nmi_enabled(struct ctl_table *table, int write, struct file *file, 
	return 0;

}



#endif

#endif /* CONFIG_SYSCTL */



int do_nmi_callback(struct pt_regs *regs, int cpu)

{
@@ -504,3 +530,4 @@ void __trigger_all_cpu_backtrace(void) 


EXPORT_SYMBOL(nmi_active);

EXPORT_SYMBOL(nmi_watchdog);

arch/x86/kernel/nmi_64.c

deleted100644 → 0
+0 −477
Original line number Diff line number Diff line 
/*

 *  NMI watchdog support on APIC systems

 *

 *  Started by Ingo Molnar <mingo@redhat.com>

 *

 *  Fixes:

 *  Mikael Pettersson	: AMD K7 support for local APIC NMI watchdog.

 *  Mikael Pettersson	: Power Management for local APIC NMI watchdog.

 *  Pavel Machek and

 *  Mikael Pettersson	: PM converted to driver model. Disable/enable API.

 */



#include <linux/nmi.h>

#include <linux/mm.h>

#include <linux/delay.h>

#include <linux/interrupt.h>

#include <linux/module.h>

#include <linux/sysdev.h>

#include <linux/sysctl.h>

#include <linux/kprobes.h>

#include <linux/cpumask.h>

#include <linux/kdebug.h>



#include <asm/smp.h>

#include <asm/nmi.h>

#include <asm/proto.h>

#include <asm/mce.h>



#include <mach_traps.h>



int unknown_nmi_panic;

int nmi_watchdog_enabled;



static cpumask_t backtrace_mask = CPU_MASK_NONE;



/* nmi_active:

 * >0: the lapic NMI watchdog is active, but can be disabled

 * <0: the lapic NMI watchdog has not been set up, and cannot

 *     be enabled

 *  0: the lapic NMI watchdog is disabled, but can be enabled

 */

atomic_t nmi_active = ATOMIC_INIT(0);		/* oprofile uses this */

static int panic_on_timeout;



unsigned int nmi_watchdog = NMI_DEFAULT;

static unsigned int nmi_hz = HZ;



static DEFINE_PER_CPU(short, wd_enabled);



static int endflag __initdata = 0;



static inline unsigned int get_nmi_count(int cpu)

{

	return cpu_pda(cpu)->__nmi_count;

}



static inline int mce_in_progress(void)

{

#ifdef CONFIG_X86_MCE

	return atomic_read(&mce_entry) > 0;

#endif

	return 0;

}



/*

 * Take the local apic timer and PIT/HPET into account. We don't

 * know which one is active, when we have highres/dyntick on

 */

static inline unsigned int get_timer_irqs(int cpu)

{

	return read_pda(apic_timer_irqs) + read_pda(irq0_irqs);

}



/* Run after command line and cpu_init init, but before all other checks */

void nmi_watchdog_default(void)

{

	if (nmi_watchdog != NMI_DEFAULT)

		return;

	nmi_watchdog = NMI_NONE;

}



#ifdef CONFIG_SMP

/* The performance counters used by NMI_LOCAL_APIC don't trigger when

 * the CPU is idle. To make sure the NMI watchdog really ticks on all

 * CPUs during the test make them busy.

 */

static __init void nmi_cpu_busy(void *data)

{

	local_irq_enable_in_hardirq();

	/* Intentionally don't use cpu_relax here. This is

	   to make sure that the performance counter really ticks,

	   even if there is a simulator or similar that catches the

	   pause instruction. On a real HT machine this is fine because

	   all other CPUs are busy with "useless" delay loops and don't

	   care if they get somewhat less cycles. */

	while (endflag == 0)

		mb();

}

#endif



int __init check_nmi_watchdog(void)

{

	unsigned int *prev_nmi_count;

	int cpu;



	if ((nmi_watchdog == NMI_NONE) || (nmi_watchdog == NMI_DISABLED))

		return 0;



	if (!atomic_read(&nmi_active))

		return 0;



	prev_nmi_count = kmalloc(NR_CPUS * sizeof(int), GFP_KERNEL);

	if (!prev_nmi_count)

		return -1;



	printk(KERN_INFO "Testing NMI watchdog ... ");



#ifdef CONFIG_SMP

	if (nmi_watchdog == NMI_LOCAL_APIC)

		smp_call_function(nmi_cpu_busy, (void *)&endflag, 0, 0);

#endif



	for_each_possible_cpu(cpu)

		prev_nmi_count[cpu] = get_nmi_count(cpu);

	local_irq_enable();

	mdelay((20*1000)/nmi_hz); // wait 20 ticks



	for_each_online_cpu(cpu) {

		if (!per_cpu(wd_enabled, cpu))

			continue;

		if (get_nmi_count(cpu) - prev_nmi_count[cpu] <= 5) {

			printk(KERN_WARNING "WARNING: CPU#%d: NMI "

			       "appears to be stuck (%d->%d)!\n",

				cpu,

				prev_nmi_count[cpu],

				get_nmi_count(cpu));

			per_cpu(wd_enabled, cpu) = 0;

			atomic_dec(&nmi_active);

		}

	}

	endflag = 1;

	if (!atomic_read(&nmi_active)) {

		kfree(prev_nmi_count);

		atomic_set(&nmi_active, -1);

		return -1;

	}

	printk("OK.\n");



	/* now that we know it works we can reduce NMI frequency to

	   something more reasonable; makes a difference in some configs */

	if (nmi_watchdog == NMI_LOCAL_APIC)

		nmi_hz = lapic_adjust_nmi_hz(1);



	kfree(prev_nmi_count);

	return 0;

}



static int __init setup_nmi_watchdog(char *str)

{

	int nmi;



	if (!strncmp(str,"panic",5)) {

		panic_on_timeout = 1;

		str = strchr(str, ',');

		if (!str)

			return 1;

		++str;

	}



	get_option(&str, &nmi);



	if ((nmi >= NMI_INVALID) || (nmi < NMI_NONE))

		return 0;



	nmi_watchdog = nmi;

	return 1;

}



__setup("nmi_watchdog=", setup_nmi_watchdog);



#ifdef CONFIG_PM



static int nmi_pm_active; /* nmi_active before suspend */



static int lapic_nmi_suspend(struct sys_device *dev, pm_message_t state)

{

	/* only CPU0 goes here, other CPUs should be offline */

	nmi_pm_active = atomic_read(&nmi_active);

	stop_apic_nmi_watchdog(NULL);

	BUG_ON(atomic_read(&nmi_active) != 0);

	return 0;

}



static int lapic_nmi_resume(struct sys_device *dev)

{

	/* only CPU0 goes here, other CPUs should be offline */

	if (nmi_pm_active > 0) {

		setup_apic_nmi_watchdog(NULL);

		touch_nmi_watchdog();

	}

	return 0;

}



static struct sysdev_class nmi_sysclass = {

	.name		= "lapic_nmi",

	.resume		= lapic_nmi_resume,

	.suspend	= lapic_nmi_suspend,

};



static struct sys_device device_lapic_nmi = {

	.id	= 0,

	.cls	= &nmi_sysclass,

};



static int __init init_lapic_nmi_sysfs(void)

{

	int error;



	/* should really be a BUG_ON but b/c this is an

	 * init call, it just doesn't work.  -dcz

	 */

	if (nmi_watchdog != NMI_LOCAL_APIC)

		return 0;



	if (atomic_read(&nmi_active) < 0)

		return 0;



	error = sysdev_class_register(&nmi_sysclass);

	if (!error)

		error = sysdev_register(&device_lapic_nmi);

	return error;

}

/* must come after the local APIC's device_initcall() */

late_initcall(init_lapic_nmi_sysfs);



#endif	/* CONFIG_PM */



static void __acpi_nmi_enable(void *__unused)

{

	apic_write_around(APIC_LVT0, APIC_DM_NMI);

}



/*

 * Enable timer based NMIs on all CPUs:

 */

void acpi_nmi_enable(void)

{

	if (atomic_read(&nmi_active) && nmi_watchdog == NMI_IO_APIC)

		on_each_cpu(__acpi_nmi_enable, NULL, 0, 1);

}



static void __acpi_nmi_disable(void *__unused)

{

	apic_write_around(APIC_LVT0, APIC_DM_NMI | APIC_LVT_MASKED);

}



/*

 * Disable timer based NMIs on all CPUs:

 */

void acpi_nmi_disable(void)

{

	if (atomic_read(&nmi_active) && nmi_watchdog == NMI_IO_APIC)

		on_each_cpu(__acpi_nmi_disable, NULL, 0, 1);

}



void setup_apic_nmi_watchdog(void *unused)

{

	if (__get_cpu_var(wd_enabled))

		return;



	/* cheap hack to support suspend/resume */

	/* if cpu0 is not active neither should the other cpus */

	if ((smp_processor_id() != 0) && (atomic_read(&nmi_active) <= 0))

		return;



	switch (nmi_watchdog) {

	case NMI_LOCAL_APIC:

		__get_cpu_var(wd_enabled) = 1;

		if (lapic_watchdog_init(nmi_hz) < 0) {

			__get_cpu_var(wd_enabled) = 0;

			return;

		}

		/* FALL THROUGH */

	case NMI_IO_APIC:

		__get_cpu_var(wd_enabled) = 1;

		atomic_inc(&nmi_active);

	}

}



void stop_apic_nmi_watchdog(void *unused)

{

	/* only support LOCAL and IO APICs for now */

	if ((nmi_watchdog != NMI_LOCAL_APIC) &&

	    (nmi_watchdog != NMI_IO_APIC))

	    	return;

	if (__get_cpu_var(wd_enabled) == 0)

		return;

	if (nmi_watchdog == NMI_LOCAL_APIC)

		lapic_watchdog_stop();

	__get_cpu_var(wd_enabled) = 0;

	atomic_dec(&nmi_active);

}



/*

 * the best way to detect whether a CPU has a 'hard lockup' problem

 * is to check it's local APIC timer IRQ counts. If they are not

 * changing then that CPU has some problem.

 *

 * as these watchdog NMI IRQs are generated on every CPU, we only

 * have to check the current processor.

 */



static DEFINE_PER_CPU(unsigned, last_irq_sum);

static DEFINE_PER_CPU(local_t, alert_counter);

static DEFINE_PER_CPU(int, nmi_touch);



void touch_nmi_watchdog(void)

{

	if (nmi_watchdog > 0) {

		unsigned cpu;



		/*

 		 * Tell other CPUs to reset their alert counters. We cannot

		 * do it ourselves because the alert count increase is not

		 * atomic.

		 */

		for_each_present_cpu(cpu) {

			if (per_cpu(nmi_touch, cpu) != 1)

				per_cpu(nmi_touch, cpu) = 1;

		}

	}



	touch_softlockup_watchdog();

}

EXPORT_SYMBOL(touch_nmi_watchdog);



notrace __kprobes int

nmi_watchdog_tick(struct pt_regs *regs, unsigned reason)

{

	unsigned int sum;

	int touched = 0;

	int cpu = smp_processor_id();

	int rc = 0;



	/* check for other users first */

	if (notify_die(DIE_NMI, "nmi", regs, reason, 2, SIGINT)

			== NOTIFY_STOP) {

		rc = 1;

		touched = 1;

	}



	sum = get_timer_irqs(cpu);



	if (__get_cpu_var(nmi_touch)) {

		__get_cpu_var(nmi_touch) = 0;

		touched = 1;

	}



	if (cpu_isset(cpu, backtrace_mask)) {

		static DEFINE_SPINLOCK(lock);	/* Serialise the printks */



		spin_lock(&lock);

		printk("NMI backtrace for cpu %d\n", cpu);

		dump_stack();

		spin_unlock(&lock);

		cpu_clear(cpu, backtrace_mask);

	}



	if (mce_in_progress())

		touched = 1;



	/* if the apic timer isn't firing, this cpu isn't doing much */

	if (!touched && __get_cpu_var(last_irq_sum) == sum) {

		/*

		 * Ayiee, looks like this CPU is stuck ...

		 * wait a few IRQs (5 seconds) before doing the oops ...

		 */

		local_inc(&__get_cpu_var(alert_counter));

		if (local_read(&__get_cpu_var(alert_counter)) == 5*nmi_hz)

			die_nmi("NMI Watchdog detected LOCKUP",

				regs, panic_on_timeout);

	} else {

		__get_cpu_var(last_irq_sum) = sum;

		local_set(&__get_cpu_var(alert_counter), 0);

	}



	/* see if the nmi watchdog went off */

	if (!__get_cpu_var(wd_enabled))

		return rc;

	switch (nmi_watchdog) {

	case NMI_LOCAL_APIC:

		rc |= lapic_wd_event(nmi_hz);

		break;

	case NMI_IO_APIC:

		/* don't know how to accurately check for this.

		 * just assume it was a watchdog timer interrupt

		 * This matches the old behaviour.

		 */

		rc = 1;

		break;

	}

	return rc;

}



#ifdef CONFIG_SYSCTL



static int unknown_nmi_panic_callback(struct pt_regs *regs, int cpu)

{

	unsigned char reason = get_nmi_reason();

	char buf[64];



	sprintf(buf, "NMI received for unknown reason %02x\n", reason);

	die_nmi(buf, regs, 1);	/* Always panic here */

	return 0;

}



/*

 * proc handler for /proc/sys/kernel/nmi

 */

int proc_nmi_enabled(struct ctl_table *table, int write, struct file *file,

			void __user *buffer, size_t *length, loff_t *ppos)

{

	int old_state;



	nmi_watchdog_enabled = (atomic_read(&nmi_active) > 0) ? 1 : 0;

	old_state = nmi_watchdog_enabled;

	proc_dointvec(table, write, file, buffer, length, ppos);

	if (!!old_state == !!nmi_watchdog_enabled)

		return 0;



	if (atomic_read(&nmi_active) < 0 || nmi_watchdog == NMI_DISABLED) {

		printk( KERN_WARNING "NMI watchdog is permanently disabled\n");

		return -EIO;

	}



	/* if nmi_watchdog is not set yet, then set it */

	nmi_watchdog_default();



	if (nmi_watchdog == NMI_LOCAL_APIC) {

		if (nmi_watchdog_enabled)

			enable_lapic_nmi_watchdog();

		else

			disable_lapic_nmi_watchdog();

	} else {

		printk( KERN_WARNING

			"NMI watchdog doesn't know what hardware to touch\n");

		return -EIO;

	}

	return 0;

}



#endif



int do_nmi_callback(struct pt_regs *regs, int cpu)

{

#ifdef CONFIG_SYSCTL

	if (unknown_nmi_panic)

		return unknown_nmi_panic_callback(regs, cpu);

#endif

	return 0;

}



void __trigger_all_cpu_backtrace(void)

{

	int i;



	backtrace_mask = cpu_online_map;

	/* Wait for up to 10 seconds for all CPUs to do the backtrace */

	for (i = 0; i < 10 * 1000; i++) {

		if (cpus_empty(backtrace_mask))

			break;

		mdelay(1);

	}

}



EXPORT_SYMBOL(nmi_active);

EXPORT_SYMBOL(nmi_watchdog);