procfs: make errno values consistent when open pident vs exit(2) race occurs

[linux-2.6/verdex.git] / kernel / irq / handle.c

/*
 * 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 <trace/irq.h>
#include <linux/bootmem.h>

#include "internals.h"

/*
 * lockdep: we want to handle all irq_desc locks as a single lock-class:
 */
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);
}

#if defined(CONFIG_SMP) && defined(CONFIG_GENERIC_HARDIRQS)
static void __init init_irq_default_affinity(void)
{
        alloc_bootmem_cpumask_var(&irq_default_affinity);
        cpumask_setall(irq_default_affinity);
}
#else
static void __init init_irq_default_affinity(void)
{
}
#endif

/*
 * 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);

#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),
};

void init_kstat_irqs(struct irq_desc *desc, int cpu, int nr)
{
        int node;
        void *ptr;

        node = cpu_to_node(cpu);
        ptr = kzalloc_node(nr * sizeof(*desc->kstat_irqs), GFP_ATOMIC, node);

        /*
         * don't overwite if can not get new one
         * init_copy_kstat_irqs() could still use old one
         */
        if (ptr) {
                printk(KERN_DEBUG "  alloc kstat_irqs on cpu %d node %d\n",
                         cpu, node);
                desc->kstat_irqs = ptr;
        }
}

static void init_one_irq_desc(int irq, struct irq_desc *desc, int cpu)
{
        memcpy(desc, &irq_desc_init, sizeof(struct irq_desc));

        spin_lock_init(&desc->lock);
        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);
        }
        if (!init_alloc_desc_masks(desc, cpu, false)) {
                printk(KERN_ERR "can not alloc irq_desc cpumasks\n");
                BUG_ON(1);
        }
        arch_init_chip_data(desc, cpu);
}

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

struct irq_desc **irq_desc_ptrs __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),
        }
};

static unsigned int *kstat_irqs_legacy;

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

        init_irq_default_affinity();

         /* initialize nr_irqs based on nr_cpu_ids */
        arch_probe_nr_irqs();
        printk(KERN_INFO "NR_IRQS:%d nr_irqs:%d\n", NR_IRQS, nr_irqs);

        desc = irq_desc_legacy;
        legacy_count = ARRAY_SIZE(irq_desc_legacy);

        /* allocate irq_desc_ptrs array based on nr_irqs */
        irq_desc_ptrs = alloc_bootmem(nr_irqs * sizeof(void *));

        /* allocate based on nr_cpu_ids */
        /* FIXME: invert kstat_irgs, and it'd be a per_cpu_alloc'd thing */
        kstat_irqs_legacy = alloc_bootmem(NR_IRQS_LEGACY * nr_cpu_ids *
                                          sizeof(int));

        for (i = 0; i < legacy_count; i++) {
                desc[i].irq = i;
                desc[i].kstat_irqs = kstat_irqs_legacy + i * nr_cpu_ids;
                lockdep_set_class(&desc[i].lock, &irq_desc_lock_class);
                init_alloc_desc_masks(&desc[i], 0, true);
                irq_desc_ptrs[i] = desc + i;
        }

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

        return arch_early_irq_init();
}

struct irq_desc *irq_to_desc(unsigned int irq)
{
        if (irq_desc_ptrs && irq < nr_irqs)
                return irq_desc_ptrs[irq];

        return 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) {
                WARN(1, "irq (%d) >= nr_irqs (%d) in irq_to_desc_alloc\n",
                        irq, nr_irqs);
                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 /* !CONFIG_SPARSE_IRQ */

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),
        }
};

static unsigned int kstat_irqs_all[NR_IRQS][NR_CPUS];
int __init early_irq_init(void)
{
        struct irq_desc *desc;
        int count;
        int i;

        init_irq_default_affinity();

        printk(KERN_INFO "NR_IRQS:%d\n", NR_IRQS);

        desc = irq_desc;
        count = ARRAY_SIZE(irq_desc);

        for (i = 0; i < count; i++) {
                desc[i].irq = i;
                init_alloc_desc_masks(&desc[i], 0, true);
                desc[i].kstat_irqs = kstat_irqs_all[i];
        }
        return arch_early_irq_init();
}

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

struct irq_desc *irq_to_desc_alloc_cpu(unsigned int irq, int cpu)
{
        return irq_to_desc(irq);
}
#endif /* !CONFIG_SPARSE_IRQ */

void clear_kstat_irqs(struct irq_desc *desc)
{
        memset(desc->kstat_irqs, 0, nr_cpu_ids * sizeof(*(desc->kstat_irqs)));
}

/*
 * 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;
}

static void warn_no_thread(unsigned int irq, struct irqaction *action)
{
        if (test_and_set_bit(IRQTF_WARNED, &action->thread_flags))
                return;

        printk(KERN_WARNING "IRQ %d device %s returned IRQ_WAKE_THREAD "
               "but no thread function available.", irq, action->name);
}

DEFINE_TRACE(irq_handler_entry);
DEFINE_TRACE(irq_handler_exit);

/**
 * 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 {
                trace_irq_handler_entry(irq, action);
                ret = action->handler(irq, action->dev_id);
                trace_irq_handler_exit(irq, action, ret);

                switch (ret) {
                case IRQ_WAKE_THREAD:
                        /*
                         * Set result to handled so the spurious check
                         * does not trigger.
                         */
                        ret = IRQ_HANDLED;

                        /*
                         * Catch drivers which return WAKE_THREAD but
                         * did not set up a thread function
                         */
                        if (unlikely(!action->thread_fn)) {
                                warn_no_thread(irq, action);
                                break;
                        }

                        /*
                         * Wake up the handler thread for this
                         * action. In case the thread crashed and was
                         * killed we just pretend that we handled the
                         * interrupt. The hardirq handler above has
                         * disabled the device interrupt, so no irq
                         * storm is lurking.
                         */
                        if (likely(!test_bit(IRQTF_DIED,
                                             &action->thread_flags))) {
                                set_bit(IRQTF_RUNTHREAD, &action->thread_flags);
                                wake_up_process(action->thread);
                        }

                        /* Fall through to add to randomness */
                case IRQ_HANDLED:
                        status |= action->flags;
                        break;

                default:
                        break;
                }

                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

#ifdef CONFIG_ENABLE_WARN_DEPRECATED
# warning __do_IRQ is deprecated. Please convert to proper flow handlers
#endif

/**
 * __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);
                        /* get new one */
                        desc = irq_remap_to_desc(irq, desc);
                }
                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);
                desc = irq_remap_to_desc(irq, desc);
        }
        /*
         * 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

void early_init_irq_lock_class(void)
{
        struct irq_desc *desc;
        int i;

        for_each_irq_desc(i, desc) {
                lockdep_set_class(&desc->lock, &irq_desc_lock_class);
        }
}

unsigned int kstat_irqs_cpu(unsigned int irq, int cpu)
{
        struct irq_desc *desc = irq_to_desc(irq);
        return desc ? desc->kstat_irqs[cpu] : 0;
}
EXPORT_SYMBOL(kstat_irqs_cpu);