kernel/irq/handle.c - maze/linux - Git at Google

 /*
  * linux/kernel/irq/handle.c
  *
  * Copyright (C) 1992, 1998-2006 Linus Torvalds, Ingo Molnar
  * Copyright (C) 2005-2006, Thomas Gleixner, Russell King
  *
  * This file contains the core interrupt handling code.
  *
  * Detailed information is available in Documentation/DocBook/genericirq
  *
  */

 #include <linux/irq.h>
 #include <linux/module.h>
 #include <linux/random.h>
 #include <linux/interrupt.h>
 #include <linux/kernel_stat.h>
 #include <linux/rculist.h>
 #include <linux/hash.h>

 #include "internals.h"

 /*
  * lockdep: we want to handle all irq_desc locks as a single lock-class:
  */
 static struct lock_class_key irq_desc_lock_class;

 /**
  * handle_bad_irq - handle spurious and unhandled irqs
  * @irq:       the interrupt number
  * @desc:      description of the interrupt
  *
  * Handles spurious and unhandled IRQ's. It also prints a debugmessage.
  */
 void handle_bad_irq(unsigned int irq, struct irq_desc *desc)
 {
 	print_irq_desc(irq, desc);
 	kstat_incr_irqs_this_cpu(irq, desc);
 	ack_bad_irq(irq);
 }

 /*
  * Linux has a controller-independent interrupt architecture.
  * Every controller has a 'controller-template', that is used
  * by the main code to do the right thing. Each driver-visible
  * interrupt source is transparently wired to the appropriate
  * controller. Thus drivers need not be aware of the
  * interrupt-controller.
  *
  * The code is designed to be easily extended with new/different
  * interrupt controllers, without having to do assembly magic or
  * having to touch the generic code.
  *
  * Controller mappings for all interrupt sources:
  */
 int nr_irqs = NR_IRQS;
 EXPORT_SYMBOL_GPL(nr_irqs);

 void __init __attribute__((weak)) arch_early_irq_init(void)
 {
 }

 #ifdef CONFIG_SPARSE_IRQ
 static struct irq_desc irq_desc_init = {
 	.irq	    = -1,
 	.status	    = IRQ_DISABLED,
 	.chip	    = &no_irq_chip,
 	.handle_irq = handle_bad_irq,
 	.depth      = 1,
 	.lock       = __SPIN_LOCK_UNLOCKED(irq_desc_init.lock),
 #ifdef CONFIG_SMP
 	.affinity   = CPU_MASK_ALL
 #endif
 };

 static void init_kstat_irqs(struct irq_desc *desc, int cpu, int nr)
 {
 	unsigned long bytes;
 	char *ptr;
 	int node;

 	/* Compute how many bytes we need per irq and allocate them */
 	bytes = nr * sizeof(unsigned int);

 	node = cpu_to_node(cpu);
 	ptr = kzalloc_node(bytes, GFP_ATOMIC, node);
 	printk(KERN_DEBUG "  alloc kstat_irqs on cpu %d node %d\n", cpu, node);

 	if (ptr)
 		desc->kstat_irqs = (unsigned int *)ptr;
 }

 void __attribute__((weak)) arch_init_chip_data(struct irq_desc *desc, int cpu)
 {
 }

 static void init_one_irq_desc(int irq, struct irq_desc *desc, int cpu)
 {
 	memcpy(desc, &irq_desc_init, sizeof(struct irq_desc));
 	desc->irq = irq;
 #ifdef CONFIG_SMP
 	desc->cpu = cpu;
 #endif
 	lockdep_set_class(&desc->lock, &irq_desc_lock_class);
 	init_kstat_irqs(desc, cpu, nr_cpu_ids);
 	if (!desc->kstat_irqs) {
 		printk(KERN_ERR "can not alloc kstat_irqs\n");
 		BUG_ON(1);
 	}
 	arch_init_chip_data(desc, cpu);
 }

 /*
  * Protect the sparse_irqs:
  */
 static DEFINE_SPINLOCK(sparse_irq_lock);

 struct irq_desc *irq_desc_ptrs[NR_IRQS] __read_mostly;

 static struct irq_desc irq_desc_legacy[NR_IRQS_LEGACY] __cacheline_aligned_in_smp = {
 	[0 ... NR_IRQS_LEGACY-1] = {
 		.irq	    = -1,
 		.status	    = IRQ_DISABLED,
 		.chip	    = &no_irq_chip,
 		.handle_irq = handle_bad_irq,
 		.depth	    = 1,
 		.lock	    = __SPIN_LOCK_UNLOCKED(irq_desc_init.lock),
 #ifdef CONFIG_SMP
 		.affinity   = CPU_MASK_ALL
 #endif
 	}
 };

 /* FIXME: use bootmem alloc ...*/
 static unsigned int kstat_irqs_legacy[NR_IRQS_LEGACY][NR_CPUS];

 void __init early_irq_init(void)
 {
 	struct irq_desc *desc;
 	int legacy_count;
 	int i;

 	desc = irq_desc_legacy;
 	legacy_count = ARRAY_SIZE(irq_desc_legacy);

 	for (i = 0; i < legacy_count; i++) {
 		desc[i].irq = i;
 		desc[i].kstat_irqs = kstat_irqs_legacy[i];

 		irq_desc_ptrs[i] = desc + i;
 	}

 	for (i = legacy_count; i < NR_IRQS; i++)
 		irq_desc_ptrs[i] = NULL;

 	arch_early_irq_init();
 }

 struct irq_desc *irq_to_desc(unsigned int irq)
 {
 	return (irq < NR_IRQS) ? irq_desc_ptrs[irq] : NULL;
 }

 struct irq_desc *irq_to_desc_alloc_cpu(unsigned int irq, int cpu)
 {
 	struct irq_desc *desc;
 	unsigned long flags;
 	int node;

 	if (irq >= NR_IRQS) {
 		printk(KERN_WARNING "irq >= NR_IRQS in irq_to_desc_alloc: %d %d\n",
 				irq, NR_IRQS);
 		WARN_ON(1);
 		return NULL;
 	}

 	desc = irq_desc_ptrs[irq];
 	if (desc)
 		return desc;

 	spin_lock_irqsave(&sparse_irq_lock, flags);

 	/* We have to check it to avoid races with another CPU */
 	desc = irq_desc_ptrs[irq];
 	if (desc)
 		goto out_unlock;

 	node = cpu_to_node(cpu);
 	desc = kzalloc_node(sizeof(*desc), GFP_ATOMIC, node);
 	printk(KERN_DEBUG "  alloc irq_desc for %d on cpu %d node %d\n",
 		 irq, cpu, node);
 	if (!desc) {
 		printk(KERN_ERR "can not alloc irq_desc\n");
 		BUG_ON(1);
 	}
 	init_one_irq_desc(irq, desc, cpu);

 	irq_desc_ptrs[irq] = desc;

 out_unlock:
 	spin_unlock_irqrestore(&sparse_irq_lock, flags);

 	return desc;
 }

 #else

 struct irq_desc irq_desc[NR_IRQS] __cacheline_aligned_in_smp = {
 	[0 ... NR_IRQS-1] = {
 		.status = IRQ_DISABLED,
 		.chip = &no_irq_chip,
 		.handle_irq = handle_bad_irq,
 		.depth = 1,
 		.lock = __SPIN_LOCK_UNLOCKED(irq_desc->lock),
 #ifdef CONFIG_SMP
 		.affinity = CPU_MASK_ALL
 #endif
 	}
 };

 #endif

 /*
  * What should we do if we get a hw irq event on an illegal vector?
  * Each architecture has to answer this themself.
  */
 static void ack_bad(unsigned int irq)
 {
 	struct irq_desc *desc = irq_to_desc(irq);

 	print_irq_desc(irq, desc);
 	ack_bad_irq(irq);
 }

 /*
  * NOP functions
  */
 static void noop(unsigned int irq)
 {
 }

 static unsigned int noop_ret(unsigned int irq)
 {
 	return 0;
 }

 /*
  * Generic no controller implementation
  */
 struct irq_chip no_irq_chip = {
 	.name		= "none",
 	.startup	= noop_ret,
 	.shutdown	= noop,
 	.enable		= noop,
 	.disable	= noop,
 	.ack		= ack_bad,
 	.end		= noop,
 };

 /*
  * Generic dummy implementation which can be used for
  * real dumb interrupt sources
  */
 struct irq_chip dummy_irq_chip = {
 	.name		= "dummy",
 	.startup	= noop_ret,
 	.shutdown	= noop,
 	.enable		= noop,
 	.disable	= noop,
 	.ack		= noop,
 	.mask		= noop,
 	.unmask		= noop,
 	.end		= noop,
 };

 /*
  * Special, empty irq handler:
  */
 irqreturn_t no_action(int cpl, void *dev_id)
 {
 	return IRQ_NONE;
 }

 /**
  * handle_IRQ_event - irq action chain handler
  * @irq:	the interrupt number
  * @action:	the interrupt action chain for this irq
  *
  * Handles the action chain of an irq event
  */
 irqreturn_t handle_IRQ_event(unsigned int irq, struct irqaction *action)
 {
 	irqreturn_t ret, retval = IRQ_NONE;
 	unsigned int status = 0;

 	if (!(action->flags & IRQF_DISABLED))
 		local_irq_enable_in_hardirq();

 	do {
 		ret = action->handler(irq, action->dev_id);
 		if (ret == IRQ_HANDLED)
 			status |= action->flags;
 		retval |= ret;
 		action = action->next;
 	} while (action);

 	if (status & IRQF_SAMPLE_RANDOM)
 		add_interrupt_randomness(irq);
 	local_irq_disable();

 	return retval;
 }

 #ifndef CONFIG_GENERIC_HARDIRQS_NO__DO_IRQ
 /**
  * __do_IRQ - original all in one highlevel IRQ handler
  * @irq:	the interrupt number
  *
  * __do_IRQ handles all normal device IRQ's (the special
  * SMP cross-CPU interrupts have their own specific
  * handlers).
  *
  * This is the original x86 implementation which is used for every
  * interrupt type.
  */
 unsigned int __do_IRQ(unsigned int irq)
 {
 	struct irq_desc *desc = irq_to_desc(irq);
 	struct irqaction *action;
 	unsigned int status;

 	kstat_incr_irqs_this_cpu(irq, desc);

 	if (CHECK_IRQ_PER_CPU(desc->status)) {
 		irqreturn_t action_ret;

 		/*
 		 * No locking required for CPU-local interrupts:
 		 */
 		if (desc->chip->ack)
 			desc->chip->ack(irq);
 		if (likely(!(desc->status & IRQ_DISABLED))) {
 			action_ret = handle_IRQ_event(irq, desc->action);
 			if (!noirqdebug)
 				note_interrupt(irq, desc, action_ret);
 		}
 		desc->chip->end(irq);
 		return 1;
 	}

 	spin_lock(&desc->lock);
 	if (desc->chip->ack)
 		desc->chip->ack(irq);
 	/*
 	 * REPLAY is when Linux resends an IRQ that was dropped earlier
 	 * WAITING is used by probe to mark irqs that are being tested
 	 */
 	status = desc->status & ~(IRQ_REPLAY | IRQ_WAITING);
 	status |= IRQ_PENDING; /* we _want_ to handle it */

 	/*
 	 * If the IRQ is disabled for whatever reason, we cannot
 	 * use the action we have.
 	 */
 	action = NULL;
 	if (likely(!(status & (IRQ_DISABLED | IRQ_INPROGRESS)))) {
 		action = desc->action;
 		status &= ~IRQ_PENDING; /* we commit to handling */
 		status |= IRQ_INPROGRESS; /* we are handling it */
 	}
 	desc->status = status;

 	/*
 	 * If there is no IRQ handler or it was disabled, exit early.
 	 * Since we set PENDING, if another processor is handling
 	 * a different instance of this same irq, the other processor
 	 * will take care of it.
 	 */
 	if (unlikely(!action))
 		goto out;

 	/*
 	 * Edge triggered interrupts need to remember
 	 * pending events.
 	 * This applies to any hw interrupts that allow a second
 	 * instance of the same irq to arrive while we are in do_IRQ
 	 * or in the handler. But the code here only handles the _second_
 	 * instance of the irq, not the third or fourth. So it is mostly
 	 * useful for irq hardware that does not mask cleanly in an
 	 * SMP environment.
 	 */
 	for (;;) {
 		irqreturn_t action_ret;

 		spin_unlock(&desc->lock);

 		action_ret = handle_IRQ_event(irq, action);
 		if (!noirqdebug)
 			note_interrupt(irq, desc, action_ret);

 		spin_lock(&desc->lock);
 		if (likely(!(desc->status & IRQ_PENDING)))
 			break;
 		desc->status &= ~IRQ_PENDING;
 	}
 	desc->status &= ~IRQ_INPROGRESS;

 out:
 	/*
 	 * The ->end() handler has to deal with interrupts which got
 	 * disabled while the handler was running.
 	 */
 	desc->chip->end(irq);
 	spin_unlock(&desc->lock);

 	return 1;
 }
 #endif


 #ifdef CONFIG_TRACE_IRQFLAGS
 void early_init_irq_lock_class(void)
 {
 #ifndef CONFIG_SPARSE_IRQ
 	struct irq_desc *desc;
 	int i;

 	for_each_irq_desc(i, desc) {
 		if (!desc)
 			continue;

 		lockdep_set_class(&desc->lock, &irq_desc_lock_class);
 	}
 #endif
 }
 #endif

 #ifdef CONFIG_SPARSE_IRQ
 unsigned int kstat_irqs_cpu(unsigned int irq, int cpu)
 {
 	struct irq_desc *desc = irq_to_desc(irq);
 	return desc->kstat_irqs[cpu];
 }
 #endif
 EXPORT_SYMBOL(kstat_irqs_cpu);
	/*
	* linux/kernel/irq/handle.c
	*
	* Copyright (C) 1992, 1998-2006 Linus Torvalds, Ingo Molnar
	* Copyright (C) 2005-2006, Thomas Gleixner, Russell King
	*
	* This file contains the core interrupt handling code.
	*
	* Detailed information is available in Documentation/DocBook/genericirq
	*
	*/

	#include <linux/irq.h>
	#include <linux/module.h>
	#include <linux/random.h>
	#include <linux/interrupt.h>
	#include <linux/kernel_stat.h>
	#include <linux/rculist.h>
	#include <linux/hash.h>

	#include "internals.h"

	/*
	* lockdep: we want to handle all irq_desc locks as a single lock-class:
	*/
	static struct lock_class_key irq_desc_lock_class;

	/**
	* handle_bad_irq - handle spurious and unhandled irqs
	* @irq: the interrupt number
	* @desc: description of the interrupt
	*
	* Handles spurious and unhandled IRQ's. It also prints a debugmessage.
	*/
	void handle_bad_irq(unsigned int irq, struct irq_desc *desc)
	{
	print_irq_desc(irq, desc);
	kstat_incr_irqs_this_cpu(irq, desc);
	ack_bad_irq(irq);
	}

	/*
	* Linux has a controller-independent interrupt architecture.
	* Every controller has a 'controller-template', that is used
	* by the main code to do the right thing. Each driver-visible
	* interrupt source is transparently wired to the appropriate
	* controller. Thus drivers need not be aware of the
	* interrupt-controller.
	*
	* The code is designed to be easily extended with new/different
	* interrupt controllers, without having to do assembly magic or
	* having to touch the generic code.
	*
	* Controller mappings for all interrupt sources:
	*/
	int nr_irqs = NR_IRQS;
	EXPORT_SYMBOL_GPL(nr_irqs);

	void __init __attribute__((weak)) arch_early_irq_init(void)
	{
	}

	#ifdef CONFIG_SPARSE_IRQ
	static struct irq_desc irq_desc_init = {
	.irq = -1,
	.status = IRQ_DISABLED,
	.chip = &no_irq_chip,
	.handle_irq = handle_bad_irq,
	.depth = 1,
	.lock = __SPIN_LOCK_UNLOCKED(irq_desc_init.lock),
	#ifdef CONFIG_SMP
	.affinity = CPU_MASK_ALL
	#endif
	};

	static void init_kstat_irqs(struct irq_desc *desc, int cpu, int nr)
	{
	unsigned long bytes;
	char *ptr;
	int node;

	/* Compute how many bytes we need per irq and allocate them */
	bytes = nr * sizeof(unsigned int);

	node = cpu_to_node(cpu);
	ptr = kzalloc_node(bytes, GFP_ATOMIC, node);
	printk(KERN_DEBUG " alloc kstat_irqs on cpu %d node %d\n", cpu, node);

	if (ptr)
	desc->kstat_irqs = (unsigned int *)ptr;
	}

	void __attribute__((weak)) arch_init_chip_data(struct irq_desc *desc, int cpu)
	{
	}

	static void init_one_irq_desc(int irq, struct irq_desc *desc, int cpu)
	{
	memcpy(desc, &irq_desc_init, sizeof(struct irq_desc));
	desc->irq = irq;
	#ifdef CONFIG_SMP
	desc->cpu = cpu;
	#endif
	lockdep_set_class(&desc->lock, &irq_desc_lock_class);
	init_kstat_irqs(desc, cpu, nr_cpu_ids);
	if (!desc->kstat_irqs) {
	printk(KERN_ERR "can not alloc kstat_irqs\n");
	BUG_ON(1);
	}
	arch_init_chip_data(desc, cpu);
	}

	/*
	* Protect the sparse_irqs:
	*/
	static DEFINE_SPINLOCK(sparse_irq_lock);

	struct irq_desc *irq_desc_ptrs[NR_IRQS] __read_mostly;

	static struct irq_desc irq_desc_legacy[NR_IRQS_LEGACY] __cacheline_aligned_in_smp = {
	[0 ... NR_IRQS_LEGACY-1] = {
	.irq = -1,
	.status = IRQ_DISABLED,
	.chip = &no_irq_chip,
	.handle_irq = handle_bad_irq,
	.depth = 1,
	.lock = __SPIN_LOCK_UNLOCKED(irq_desc_init.lock),
	#ifdef CONFIG_SMP
	.affinity = CPU_MASK_ALL
	#endif
	}
	};

	/* FIXME: use bootmem alloc ...*/
	static unsigned int kstat_irqs_legacy[NR_IRQS_LEGACY][NR_CPUS];

	void __init early_irq_init(void)
	{
	struct irq_desc *desc;
	int legacy_count;
	int i;

	desc = irq_desc_legacy;
	legacy_count = ARRAY_SIZE(irq_desc_legacy);

	for (i = 0; i < legacy_count; i++) {
	desc[i].irq = i;
	desc[i].kstat_irqs = kstat_irqs_legacy[i];

	irq_desc_ptrs[i] = desc + i;
	}

	for (i = legacy_count; i < NR_IRQS; i++)
	irq_desc_ptrs[i] = NULL;

	arch_early_irq_init();
	}

	struct irq_desc *irq_to_desc(unsigned int irq)
	{
	return (irq < NR_IRQS) ? irq_desc_ptrs[irq] : NULL;
	}

	struct irq_desc *irq_to_desc_alloc_cpu(unsigned int irq, int cpu)
	{
	struct irq_desc *desc;
	unsigned long flags;
	int node;

	if (irq >= NR_IRQS) {
	printk(KERN_WARNING "irq >= NR_IRQS in irq_to_desc_alloc: %d %d\n",
	irq, NR_IRQS);
	WARN_ON(1);
	return NULL;
	}

	desc = irq_desc_ptrs[irq];
	if (desc)
	return desc;

	spin_lock_irqsave(&sparse_irq_lock, flags);

	/* We have to check it to avoid races with another CPU */
	desc = irq_desc_ptrs[irq];
	if (desc)
	goto out_unlock;

	node = cpu_to_node(cpu);
	desc = kzalloc_node(sizeof(*desc), GFP_ATOMIC, node);
	printk(KERN_DEBUG " alloc irq_desc for %d on cpu %d node %d\n",
	irq, cpu, node);
	if (!desc) {
	printk(KERN_ERR "can not alloc irq_desc\n");
	BUG_ON(1);
	}
	init_one_irq_desc(irq, desc, cpu);

	irq_desc_ptrs[irq] = desc;

	out_unlock:
	spin_unlock_irqrestore(&sparse_irq_lock, flags);

	return desc;
	}

	#else

	struct irq_desc irq_desc[NR_IRQS] __cacheline_aligned_in_smp = {
	[0 ... NR_IRQS-1] = {
	.status = IRQ_DISABLED,
	.chip = &no_irq_chip,
	.handle_irq = handle_bad_irq,
	.depth = 1,
	.lock = __SPIN_LOCK_UNLOCKED(irq_desc->lock),
	#ifdef CONFIG_SMP
	.affinity = CPU_MASK_ALL
	#endif
	}
	};

	#endif

	/*
	* What should we do if we get a hw irq event on an illegal vector?
	* Each architecture has to answer this themself.
	*/
	static void ack_bad(unsigned int irq)
	{
	struct irq_desc *desc = irq_to_desc(irq);

	print_irq_desc(irq, desc);
	ack_bad_irq(irq);
	}

	/*
	* NOP functions
	*/
	static void noop(unsigned int irq)
	{
	}

	static unsigned int noop_ret(unsigned int irq)
	{
	return 0;
	}

	/*
	* Generic no controller implementation
	*/
	struct irq_chip no_irq_chip = {
	.name = "none",
	.startup = noop_ret,
	.shutdown = noop,
	.enable = noop,
	.disable = noop,
	.ack = ack_bad,
	.end = noop,
	};

	/*
	* Generic dummy implementation which can be used for
	* real dumb interrupt sources
	*/
	struct irq_chip dummy_irq_chip = {
	.name = "dummy",
	.startup = noop_ret,
	.shutdown = noop,
	.enable = noop,
	.disable = noop,
	.ack = noop,
	.mask = noop,
	.unmask = noop,
	.end = noop,
	};

	/*
	* Special, empty irq handler:
	*/
	irqreturn_t no_action(int cpl, void *dev_id)
	{
	return IRQ_NONE;
	}

	/**
	* handle_IRQ_event - irq action chain handler
	* @irq: the interrupt number
	* @action: the interrupt action chain for this irq
	*
	* Handles the action chain of an irq event
	*/
	irqreturn_t handle_IRQ_event(unsigned int irq, struct irqaction *action)
	{
	irqreturn_t ret, retval = IRQ_NONE;
	unsigned int status = 0;

	if (!(action->flags & IRQF_DISABLED))
	local_irq_enable_in_hardirq();

	do {
	ret = action->handler(irq, action->dev_id);
	if (ret == IRQ_HANDLED)
	status \|= action->flags;
	retval \|= ret;
	action = action->next;
	} while (action);

	if (status & IRQF_SAMPLE_RANDOM)
	add_interrupt_randomness(irq);
	local_irq_disable();

	return retval;
	}

	#ifndef CONFIG_GENERIC_HARDIRQS_NO__DO_IRQ
	/**
	* __do_IRQ - original all in one highlevel IRQ handler
	* @irq: the interrupt number
	*
	* __do_IRQ handles all normal device IRQ's (the special
	* SMP cross-CPU interrupts have their own specific
	* handlers).
	*
	* This is the original x86 implementation which is used for every
	* interrupt type.
	*/
	unsigned int __do_IRQ(unsigned int irq)
	{
	struct irq_desc *desc = irq_to_desc(irq);
	struct irqaction *action;
	unsigned int status;

	kstat_incr_irqs_this_cpu(irq, desc);

	if (CHECK_IRQ_PER_CPU(desc->status)) {
	irqreturn_t action_ret;

	/*
	* No locking required for CPU-local interrupts:
	*/
	if (desc->chip->ack)
	desc->chip->ack(irq);
	if (likely(!(desc->status & IRQ_DISABLED))) {
	action_ret = handle_IRQ_event(irq, desc->action);
	if (!noirqdebug)
	note_interrupt(irq, desc, action_ret);
	}
	desc->chip->end(irq);
	return 1;
	}

	spin_lock(&desc->lock);
	if (desc->chip->ack)
	desc->chip->ack(irq);
	/*
	* REPLAY is when Linux resends an IRQ that was dropped earlier
	* WAITING is used by probe to mark irqs that are being tested
	*/
	status = desc->status & ~(IRQ_REPLAY \| IRQ_WAITING);
	status \|= IRQ_PENDING; /* we _want_ to handle it */

	/*
	* If the IRQ is disabled for whatever reason, we cannot
	* use the action we have.
	*/
	action = NULL;
	if (likely(!(status & (IRQ_DISABLED \| IRQ_INPROGRESS)))) {
	action = desc->action;
	status &= ~IRQ_PENDING; /* we commit to handling */
	status \|= IRQ_INPROGRESS; /* we are handling it */
	}
	desc->status = status;

	/*
	* If there is no IRQ handler or it was disabled, exit early.
	* Since we set PENDING, if another processor is handling
	* a different instance of this same irq, the other processor
	* will take care of it.
	*/
	if (unlikely(!action))
	goto out;

	/*
	* Edge triggered interrupts need to remember
	* pending events.
	* This applies to any hw interrupts that allow a second
	* instance of the same irq to arrive while we are in do_IRQ
	* or in the handler. But the code here only handles the _second_
	* instance of the irq, not the third or fourth. So it is mostly
	* useful for irq hardware that does not mask cleanly in an
	* SMP environment.
	*/
	for (;;) {
	irqreturn_t action_ret;

	spin_unlock(&desc->lock);

	action_ret = handle_IRQ_event(irq, action);
	if (!noirqdebug)
	note_interrupt(irq, desc, action_ret);

	spin_lock(&desc->lock);
	if (likely(!(desc->status & IRQ_PENDING)))
	break;
	desc->status &= ~IRQ_PENDING;
	}
	desc->status &= ~IRQ_INPROGRESS;

	out:
	/*
	* The ->end() handler has to deal with interrupts which got
	* disabled while the handler was running.
	*/
	desc->chip->end(irq);
	spin_unlock(&desc->lock);

	return 1;
	}
	#endif


	#ifdef CONFIG_TRACE_IRQFLAGS
	void early_init_irq_lock_class(void)
	{
	#ifndef CONFIG_SPARSE_IRQ
	struct irq_desc *desc;
	int i;

	for_each_irq_desc(i, desc) {
	if (!desc)
	continue;

	lockdep_set_class(&desc->lock, &irq_desc_lock_class);
	}
	#endif
	}
	#endif

	#ifdef CONFIG_SPARSE_IRQ
	unsigned int kstat_irqs_cpu(unsigned int irq, int cpu)
	{
	struct irq_desc *desc = irq_to_desc(irq);
	return desc->kstat_irqs[cpu];
	}
	#endif
	EXPORT_SYMBOL(kstat_irqs_cpu);