manage.c

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/*
 * linux/kernel/irq/manage.c
 *
 * Copyright (C) 1992, 1998-2006 Linus Torvalds, Ingo Molnar
 * Copyright (C) 2005-2006 Thomas Gleixner
 *
 * This file contains driver APIs to the irq subsystem.
 */

#define pr_fmt(fmt) "genirq: " fmt

#include <linux/irq.h>
#include <linux/kthread.h>
#include <linux/module.h>
#include <linux/random.h>
#include <linux/interrupt.h>
#include <linux/slab.h>
#include <linux/sched.h>
#include <linux/task_work.h>

#include "internals.h"

#ifdef CONFIG_IRQ_FORCED_THREADING
__read_mostly bool force_irqthreads;

static int __init setup_forced_irqthreads(char *arg)
{
    force_irqthreads = true;
    return 0;
}
early_param("threadirqs", setup_forced_irqthreads);
#endif

void synchronize_irq(unsigned int irq)
{
    struct irq_desc *desc = irq_to_desc(irq);
    bool inprogress;

    if (!desc)
        return;

    do {
        unsigned long flags;

        /*
         * Wait until we're out of the critical section.  This might
         * give the wrong answer due to the lack of memory barriers.
         */
        while (irqd_irq_inprogress(&desc->irq_data))
            cpu_relax();

        /* Ok, that indicated we're done: double-check carefully. */
        raw_spin_lock_irqsave(&desc->lock, flags);
        inprogress = irqd_irq_inprogress(&desc->irq_data);
        raw_spin_unlock_irqrestore(&desc->lock, flags);

        /* Oops, that failed? */
    } while (inprogress);

    /*
     * We made sure that no hardirq handler is running. Now verify
     * that no threaded handlers are active.
     */
    wait_event(desc->wait_for_threads, !atomic_read(&desc->threads_active));
}
EXPORT_SYMBOL(synchronize_irq);

#ifdef CONFIG_SMP
cpumask_var_t irq_default_affinity;

int irq_can_set_affinity(unsigned int irq)
{
    struct irq_desc *desc = irq_to_desc(irq);

    if (!desc || !irqd_can_balance(&desc->irq_data) ||
        !desc->irq_data.chip || !desc->irq_data.chip->irq_set_affinity)
        return 0;

    return 1;
}

void irq_set_thread_affinity(struct irq_desc *desc)
{
    struct irqaction *action = desc->action;

    while (action) {
        if (action->thread)
            set_bit(IRQTF_AFFINITY, &action->thread_flags);
        action = action->next;
    }
}

#ifdef CONFIG_GENERIC_PENDING_IRQ
static inline bool irq_can_move_pcntxt(struct irq_data *data)
{
    return irqd_can_move_in_process_context(data);
}
static inline bool irq_move_pending(struct irq_data *data)
{
    return irqd_is_setaffinity_pending(data);
}
static inline void
irq_copy_pending(struct irq_desc *desc, const struct cpumask *mask)
{
    cpumask_copy(desc->pending_mask, mask);
}
static inline void
irq_get_pending(struct cpumask *mask, struct irq_desc *desc)
{
    cpumask_copy(mask, desc->pending_mask);
}
#else
static inline bool irq_can_move_pcntxt(struct irq_data *data) { return true; }
static inline bool irq_move_pending(struct irq_data *data) { return false; }
static inline void
irq_copy_pending(struct irq_desc *desc, const struct cpumask *mask) { }
static inline void
irq_get_pending(struct cpumask *mask, struct irq_desc *desc) { }
#endif

int irq_do_set_affinity(struct irq_data *data, const struct cpumask *mask,
            bool force)
{
    struct irq_desc *desc = irq_data_to_desc(data);
    struct irq_chip *chip = irq_data_get_irq_chip(data);
    int ret;

    ret = chip->irq_set_affinity(data, mask, false);
    switch (ret) {
    case IRQ_SET_MASK_OK:
        cpumask_copy(data->affinity, mask);
    case IRQ_SET_MASK_OK_NOCOPY:
        irq_set_thread_affinity(desc);
        ret = 0;
    }

    return ret;
}

int __irq_set_affinity_locked(struct irq_data *data, const struct cpumask *mask)
{
    struct irq_chip *chip = irq_data_get_irq_chip(data);
    struct irq_desc *desc = irq_data_to_desc(data);
    int ret = 0;

    if (!chip || !chip->irq_set_affinity)
        return -EINVAL;

    if (irq_can_move_pcntxt(data)) {
        ret = irq_do_set_affinity(data, mask, false);
    } else {
        irqd_set_move_pending(data);
        irq_copy_pending(desc, mask);
    }

    if (desc->affinity_notify) {
        kref_get(&desc->affinity_notify->kref);
        schedule_work(&desc->affinity_notify->work);
    }
    irqd_set(data, IRQD_AFFINITY_SET);

    return ret;
}

int irq_set_affinity(unsigned int irq, const struct cpumask *mask)
{
    struct irq_desc *desc = irq_to_desc(irq);
    unsigned long flags;
    int ret;

    if (!desc)
        return -EINVAL;

    raw_spin_lock_irqsave(&desc->lock, flags);
    ret =  __irq_set_affinity_locked(irq_desc_get_irq_data(desc), mask);
    raw_spin_unlock_irqrestore(&desc->lock, flags);
    return ret;
}

int irq_set_affinity_hint(unsigned int irq, const struct cpumask *m)
{
    unsigned long flags;
    struct irq_desc *desc = irq_get_desc_lock(irq, &flags, IRQ_GET_DESC_CHECK_GLOBAL);

    if (!desc)
        return -EINVAL;
    desc->affinity_hint = m;
    irq_put_desc_unlock(desc, flags);
    return 0;
}
EXPORT_SYMBOL_GPL(irq_set_affinity_hint);

static void irq_affinity_notify(struct work_struct *work)
{
    struct irq_affinity_notify *notify =
        container_of(work, struct irq_affinity_notify, work);
    struct irq_desc *desc = irq_to_desc(notify->irq);
    cpumask_var_t cpumask;
    unsigned long flags;

    if (!desc || !alloc_cpumask_var(&cpumask, GFP_KERNEL))
        goto out;

    raw_spin_lock_irqsave(&desc->lock, flags);
    if (irq_move_pending(&desc->irq_data))
        irq_get_pending(cpumask, desc);
    else
        cpumask_copy(cpumask, desc->irq_data.affinity);
    raw_spin_unlock_irqrestore(&desc->lock, flags);

    notify->notify(notify, cpumask);

    free_cpumask_var(cpumask);
out:
    kref_put(&notify->kref, notify->release);
}

int
irq_set_affinity_notifier(unsigned int irq, struct irq_affinity_notify *notify)
{
    struct irq_desc *desc = irq_to_desc(irq);
    struct irq_affinity_notify *old_notify;
    unsigned long flags;

    /* The release function is promised process context */
    might_sleep();

    if (!desc)
        return -EINVAL;

    /* Complete initialisation of *notify */
    if (notify) {
        notify->irq = irq;
        kref_init(&notify->kref);
        INIT_WORK(&notify->work, irq_affinity_notify);
    }

    raw_spin_lock_irqsave(&desc->lock, flags);
    old_notify = desc->affinity_notify;
    desc->affinity_notify = notify;
    raw_spin_unlock_irqrestore(&desc->lock, flags);

    if (old_notify)
        kref_put(&old_notify->kref, old_notify->release);

    return 0;
}
EXPORT_SYMBOL_GPL(irq_set_affinity_notifier);

#ifndef CONFIG_AUTO_IRQ_AFFINITY
/*
 * Generic version of the affinity autoselector.
 */
static int
setup_affinity(unsigned int irq, struct irq_desc *desc, struct cpumask *mask)
{
    struct cpumask *set = irq_default_affinity;
    int node = desc->irq_data.node;

    /* Excludes PER_CPU and NO_BALANCE interrupts */
    if (!irq_can_set_affinity(irq))
        return 0;

    /*
     * Preserve an userspace affinity setup, but make sure that
     * one of the targets is online.
     */
    if (irqd_has_set(&desc->irq_data, IRQD_AFFINITY_SET)) {
        if (cpumask_intersects(desc->irq_data.affinity,
                       cpu_online_mask))
            set = desc->irq_data.affinity;
        else
            irqd_clear(&desc->irq_data, IRQD_AFFINITY_SET);
    }

    cpumask_and(mask, cpu_online_mask, set);
    if (node != NUMA_NO_NODE) {
        const struct cpumask *nodemask = cpumask_of_node(node);

        /* make sure at least one of the cpus in nodemask is online */
        if (cpumask_intersects(mask, nodemask))
            cpumask_and(mask, mask, nodemask);
    }
    irq_do_set_affinity(&desc->irq_data, mask, false);
    return 0;
}
#else
static inline int
setup_affinity(unsigned int irq, struct irq_desc *d, struct cpumask *mask)
{
    return irq_select_affinity(irq);
}
#endif

/*
 * Called when affinity is set via /proc/irq
 */
int irq_select_affinity_usr(unsigned int irq, struct cpumask *mask)
{
    struct irq_desc *desc = irq_to_desc(irq);
    unsigned long flags;
    int ret;

    raw_spin_lock_irqsave(&desc->lock, flags);
    ret = setup_affinity(irq, desc, mask);
    raw_spin_unlock_irqrestore(&desc->lock, flags);
    return ret;
}

#else
static inline int
setup_affinity(unsigned int irq, struct irq_desc *desc, struct cpumask *mask)
{
    return 0;
}
#endif

void __disable_irq(struct irq_desc *desc, unsigned int irq, bool suspend)
{
    if (suspend) {
        if (!desc->action || (desc->action->flags & IRQF_NO_SUSPEND))
            return;
        desc->istate |= IRQS_SUSPENDED;
    }

    if (!desc->depth++)
        irq_disable(desc);
}

static int __disable_irq_nosync(unsigned int irq)
{
    unsigned long flags;
    struct irq_desc *desc = irq_get_desc_buslock(irq, &flags, IRQ_GET_DESC_CHECK_GLOBAL);

    if (!desc)
        return -EINVAL;
    __disable_irq(desc, irq, false);
    irq_put_desc_busunlock(desc, flags);
    return 0;
}

void disable_irq_nosync(unsigned int irq)
{
    __disable_irq_nosync(irq);
}
EXPORT_SYMBOL(disable_irq_nosync);

void disable_irq(unsigned int irq)
{
    if (!__disable_irq_nosync(irq))
        synchronize_irq(irq);
}
EXPORT_SYMBOL(disable_irq);

void __enable_irq(struct irq_desc *desc, unsigned int irq, bool resume)
{
    if (resume) {
        if (!(desc->istate & IRQS_SUSPENDED)) {
            if (!desc->action)
                return;
            if (!(desc->action->flags & IRQF_FORCE_RESUME))
                return;
            /* Pretend that it got disabled ! */
            desc->depth++;
        }
        desc->istate &= ~IRQS_SUSPENDED;
    }

    switch (desc->depth) {
    case 0:
 err_out:
        WARN(1, KERN_WARNING "Unbalanced enable for IRQ %d\n", irq);
        break;
    case 1: {
        if (desc->istate & IRQS_SUSPENDED)
            goto err_out;
        /* Prevent probing on this irq: */
        irq_settings_set_noprobe(desc);
        irq_enable(desc);
        check_irq_resend(desc, irq);
        /* fall-through */
    }
    default:
        desc->depth--;
    }
}

void enable_irq(unsigned int irq)
{
    unsigned long flags;
    struct irq_desc *desc = irq_get_desc_buslock(irq, &flags, IRQ_GET_DESC_CHECK_GLOBAL);

    if (!desc)
        return;
    if (WARN(!desc->irq_data.chip,
         KERN_ERR "enable_irq before setup/request_irq: irq %u\n", irq))
        goto out;

    __enable_irq(desc, irq, false);
out:
    irq_put_desc_busunlock(desc, flags);
}
EXPORT_SYMBOL(enable_irq);

static int set_irq_wake_real(unsigned int irq, unsigned int on)
{
    struct irq_desc *desc = irq_to_desc(irq);
    int ret = -ENXIO;

    if (irq_desc_get_chip(desc)->flags &  IRQCHIP_SKIP_SET_WAKE)
        return 0;

    if (desc->irq_data.chip->irq_set_wake)
        ret = desc->irq_data.chip->irq_set_wake(&desc->irq_data, on);

    return ret;
}

int irq_set_irq_wake(unsigned int irq, unsigned int on)
{
    unsigned long flags;
    struct irq_desc *desc = irq_get_desc_buslock(irq, &flags, IRQ_GET_DESC_CHECK_GLOBAL);
    int ret = 0;

    if (!desc)
        return -EINVAL;

    /* wakeup-capable irqs can be shared between drivers that
     * don't need to have the same sleep mode behaviors.
     */
    if (on) {
        if (desc->wake_depth++ == 0) {
            ret = set_irq_wake_real(irq, on);
            if (ret)
                desc->wake_depth = 0;
            else
                irqd_set(&desc->irq_data, IRQD_WAKEUP_STATE);
        }
    } else {
        if (desc->wake_depth == 0) {
            WARN(1, "Unbalanced IRQ %d wake disable\n", irq);
        } else if (--desc->wake_depth == 0) {
            ret = set_irq_wake_real(irq, on);
            if (ret)
                desc->wake_depth = 1;
            else
                irqd_clear(&desc->irq_data, IRQD_WAKEUP_STATE);
        }
    }
    irq_put_desc_busunlock(desc, flags);
    return ret;
}
EXPORT_SYMBOL(irq_set_irq_wake);

/*
 * Internal function that tells the architecture code whether a
 * particular irq has been exclusively allocated or is available
 * for driver use.
 */
int can_request_irq(unsigned int irq, unsigned long irqflags)
{
    unsigned long flags;
    struct irq_desc *desc = irq_get_desc_lock(irq, &flags, 0);
    int canrequest = 0;

    if (!desc)
        return 0;

    if (irq_settings_can_request(desc)) {
        if (desc->action)
            if (irqflags & desc->action->flags & IRQF_SHARED)
                canrequest =1;
    }
    irq_put_desc_unlock(desc, flags);
    return canrequest;
}

int __irq_set_trigger(struct irq_desc *desc, unsigned int irq,
              unsigned long flags)
{
    struct irq_chip *chip = desc->irq_data.chip;
    int ret, unmask = 0;

    if (!chip || !chip->irq_set_type) {
        /*
         * IRQF_TRIGGER_* but the PIC does not support multiple
         * flow-types?
         */
        pr_debug("No set_type function for IRQ %d (%s)\n", irq,
             chip ? (chip->name ? : "unknown") : "unknown");
        return 0;
    }

    flags &= IRQ_TYPE_SENSE_MASK;

    if (chip->flags & IRQCHIP_SET_TYPE_MASKED) {
        if (!irqd_irq_masked(&desc->irq_data))
            mask_irq(desc);
        if (!irqd_irq_disabled(&desc->irq_data))
            unmask = 1;
    }

    /* caller masked out all except trigger mode flags */
    ret = chip->irq_set_type(&desc->irq_data, flags);

    switch (ret) {
    case IRQ_SET_MASK_OK:
        irqd_clear(&desc->irq_data, IRQD_TRIGGER_MASK);
        irqd_set(&desc->irq_data, flags);

    case IRQ_SET_MASK_OK_NOCOPY:
        flags = irqd_get_trigger_type(&desc->irq_data);
        irq_settings_set_trigger_mask(desc, flags);
        irqd_clear(&desc->irq_data, IRQD_LEVEL);
        irq_settings_clr_level(desc);
        if (flags & IRQ_TYPE_LEVEL_MASK) {
            irq_settings_set_level(desc);
            irqd_set(&desc->irq_data, IRQD_LEVEL);
        }

        ret = 0;
        break;
    default:
        pr_err("Setting trigger mode %lu for irq %u failed (%pF)\n",
               flags, irq, chip->irq_set_type);
    }
    if (unmask)
        unmask_irq(desc);
    return ret;
}

/*
 * Default primary interrupt handler for threaded interrupts. Is
 * assigned as primary handler when request_threaded_irq is called
 * with handler == NULL. Useful for oneshot interrupts.
 */
static irqreturn_t irq_default_primary_handler(int irq, void *dev_id)
{
    return IRQ_WAKE_THREAD;
}

/*
 * Primary handler for nested threaded interrupts. Should never be
 * called.
 */
static irqreturn_t irq_nested_primary_handler(int irq, void *dev_id)
{
    WARN(1, "Primary handler called for nested irq %d\n", irq);
    return IRQ_NONE;
}

static int irq_wait_for_interrupt(struct irqaction *action)
{
    set_current_state(TASK_INTERRUPTIBLE);

    while (!kthread_should_stop()) {

        if (test_and_clear_bit(IRQTF_RUNTHREAD,
                       &action->thread_flags)) {
            __set_current_state(TASK_RUNNING);
            return 0;
        }
        schedule();
        set_current_state(TASK_INTERRUPTIBLE);
    }
    __set_current_state(TASK_RUNNING);
    return -1;
}

/*
 * Oneshot interrupts keep the irq line masked until the threaded
 * handler finished. unmask if the interrupt has not been disabled and
 * is marked MASKED.
 */
static void irq_finalize_oneshot(struct irq_desc *desc,
                 struct irqaction *action)
{
    if (!(desc->istate & IRQS_ONESHOT))
        return;
again:
    chip_bus_lock(desc);
    raw_spin_lock_irq(&desc->lock);

    /*
     * Implausible though it may be we need to protect us against
     * the following scenario:
     *
     * The thread is faster done than the hard interrupt handler
     * on the other CPU. If we unmask the irq line then the
     * interrupt can come in again and masks the line, leaves due
     * to IRQS_INPROGRESS and the irq line is masked forever.
     *
     * This also serializes the state of shared oneshot handlers
     * versus "desc->threads_onehsot |= action->thread_mask;" in
     * irq_wake_thread(). See the comment there which explains the
     * serialization.
     */
    if (unlikely(irqd_irq_inprogress(&desc->irq_data))) {
        raw_spin_unlock_irq(&desc->lock);
        chip_bus_sync_unlock(desc);
        cpu_relax();
        goto again;
    }

    /*
     * Now check again, whether the thread should run. Otherwise
     * we would clear the threads_oneshot bit of this thread which
     * was just set.
     */
    if (test_bit(IRQTF_RUNTHREAD, &action->thread_flags))
        goto out_unlock;

    desc->threads_oneshot &= ~action->thread_mask;

    if (!desc->threads_oneshot && !irqd_irq_disabled(&desc->irq_data) &&
        irqd_irq_masked(&desc->irq_data))
        unmask_irq(desc);

out_unlock:
    raw_spin_unlock_irq(&desc->lock);
    chip_bus_sync_unlock(desc);
}

#ifdef CONFIG_SMP
/*
 * Check whether we need to chasnge the affinity of the interrupt thread.
 */
static void
irq_thread_check_affinity(struct irq_desc *desc, struct irqaction *action)
{
    cpumask_var_t mask;

    if (!test_and_clear_bit(IRQTF_AFFINITY, &action->thread_flags))
        return;

    /*
     * In case we are out of memory we set IRQTF_AFFINITY again and
     * try again next time
     */
    if (!alloc_cpumask_var(&mask, GFP_KERNEL)) {
        set_bit(IRQTF_AFFINITY, &action->thread_flags);
        return;
    }

    raw_spin_lock_irq(&desc->lock);
    cpumask_copy(mask, desc->irq_data.affinity);
    raw_spin_unlock_irq(&desc->lock);

    set_cpus_allowed_ptr(current, mask);
    free_cpumask_var(mask);
}
#else
static inline void
irq_thread_check_affinity(struct irq_desc *desc, struct irqaction *action) { }
#endif

/*
 * Interrupts which are not explicitely requested as threaded
 * interrupts rely on the implicit bh/preempt disable of the hard irq
 * context. So we need to disable bh here to avoid deadlocks and other
 * side effects.
 */
static irqreturn_t
irq_forced_thread_fn(struct irq_desc *desc, struct irqaction *action)
{
    irqreturn_t ret;

    local_bh_disable();
    ret = action->thread_fn(action->irq, action->dev_id);
    irq_finalize_oneshot(desc, action);
    local_bh_enable();
    return ret;
}

/*
 * Interrupts explicitely requested as threaded interupts want to be
 * preemtible - many of them need to sleep and wait for slow busses to
 * complete.
 */
static irqreturn_t irq_thread_fn(struct irq_desc *desc,
        struct irqaction *action)
{
    irqreturn_t ret;

    ret = action->thread_fn(action->irq, action->dev_id);
    irq_finalize_oneshot(desc, action);
    return ret;
}

static void wake_threads_waitq(struct irq_desc *desc)
{
    if (atomic_dec_and_test(&desc->threads_active) &&
        waitqueue_active(&desc->wait_for_threads))
        wake_up(&desc->wait_for_threads);
}

static void irq_thread_dtor(struct callback_head *unused)
{
    struct task_struct *tsk = current;
    struct irq_desc *desc;
    struct irqaction *action;

    if (WARN_ON_ONCE(!(current->flags & PF_EXITING)))
        return;

    action = kthread_data(tsk);

    pr_err("exiting task \"%s\" (%d) is an active IRQ thread (irq %d)\n",
           tsk->comm ? tsk->comm : "", tsk->pid, action->irq);


    desc = irq_to_desc(action->irq);
    /*
     * If IRQTF_RUNTHREAD is set, we need to decrement
     * desc->threads_active and wake possible waiters.
     */
    if (test_and_clear_bit(IRQTF_RUNTHREAD, &action->thread_flags))
        wake_threads_waitq(desc);

    /* Prevent a stale desc->threads_oneshot */
    irq_finalize_oneshot(desc, action);
}

/*
 * Interrupt handler thread
 */
static int irq_thread(void *data)
{
    struct callback_head on_exit_work;
    static const struct sched_param param = {
        .sched_priority = MAX_USER_RT_PRIO/2,
    };
    struct irqaction *action = data;
    struct irq_desc *desc = irq_to_desc(action->irq);
    irqreturn_t (*handler_fn)(struct irq_desc *desc,
            struct irqaction *action);

    if (force_irqthreads && test_bit(IRQTF_FORCED_THREAD,
                    &action->thread_flags))
        handler_fn = irq_forced_thread_fn;
    else
        handler_fn = irq_thread_fn;

    sched_setscheduler(current, SCHED_FIFO, &param);

    init_task_work(&on_exit_work, irq_thread_dtor);
    task_work_add(current, &on_exit_work, false);

    while (!irq_wait_for_interrupt(action)) {
        irqreturn_t action_ret;

        irq_thread_check_affinity(desc, action);

        action_ret = handler_fn(desc, action);
        if (!noirqdebug)
            note_interrupt(action->irq, desc, action_ret);

        wake_threads_waitq(desc);
    }

    /*
     * This is the regular exit path. __free_irq() is stopping the
     * thread via kthread_stop() after calling
     * synchronize_irq(). So neither IRQTF_RUNTHREAD nor the
     * oneshot mask bit can be set. We cannot verify that as we
     * cannot touch the oneshot mask at this point anymore as
     * __setup_irq() might have given out currents thread_mask
     * again.
     */
    task_work_cancel(current, irq_thread_dtor);
    return 0;
}

static void irq_setup_forced_threading(struct irqaction *new)
{
    if (!force_irqthreads)
        return;
    if (new->flags & (IRQF_NO_THREAD | IRQF_PERCPU | IRQF_ONESHOT))
        return;

    new->flags |= IRQF_ONESHOT;

    if (!new->thread_fn) {
        set_bit(IRQTF_FORCED_THREAD, &new->thread_flags);
        new->thread_fn = new->handler;
        new->handler = irq_default_primary_handler;
    }
}

/*
 * Internal function to register an irqaction - typically used to
 * allocate special interrupts that are part of the architecture.
 */
static int
__setup_irq(unsigned int irq, struct irq_desc *desc, struct irqaction *new)
{
    struct irqaction *old, **old_ptr;
    unsigned long flags, thread_mask = 0;
    int ret, nested, shared = 0;
    cpumask_var_t mask;

    if (!desc)
        return -EINVAL;

    if (desc->irq_data.chip == &no_irq_chip)
        return -ENOSYS;
    if (!try_module_get(desc->owner))
        return -ENODEV;

    /*
     * Check whether the interrupt nests into another interrupt
     * thread.
     */
    nested = irq_settings_is_nested_thread(desc);
    if (nested) {
        if (!new->thread_fn) {
            ret = -EINVAL;
            goto out_mput;
        }
        /*
         * Replace the primary handler which was provided from
         * the driver for non nested interrupt handling by the
         * dummy function which warns when called.
         */
        new->handler = irq_nested_primary_handler;
    } else {
        if (irq_settings_can_thread(desc))
            irq_setup_forced_threading(new);
    }

    /*
     * Create a handler thread when a thread function is supplied
     * and the interrupt does not nest into another interrupt
     * thread.
     */
    if (new->thread_fn && !nested) {
        struct task_struct *t;

        t = kthread_create(irq_thread, new, "irq/%d-%s", irq,
                   new->name);
        if (IS_ERR(t)) {
            ret = PTR_ERR(t);
            goto out_mput;
        }
        /*
         * We keep the reference to the task struct even if
         * the thread dies to avoid that the interrupt code
         * references an already freed task_struct.
         */
        get_task_struct(t);
        new->thread = t;
    }

    if (!alloc_cpumask_var(&mask, GFP_KERNEL)) {
        ret = -ENOMEM;
        goto out_thread;
    }

    /*
     * Drivers are often written to work w/o knowledge about the
     * underlying irq chip implementation, so a request for a
     * threaded irq without a primary hard irq context handler
     * requires the ONESHOT flag to be set. Some irq chips like
     * MSI based interrupts are per se one shot safe. Check the
     * chip flags, so we can avoid the unmask dance at the end of
     * the threaded handler for those.
     */
    if (desc->irq_data.chip->flags & IRQCHIP_ONESHOT_SAFE)
        new->flags &= ~IRQF_ONESHOT;

    /*
     * The following block of code has to be executed atomically
     */
    raw_spin_lock_irqsave(&desc->lock, flags);
    old_ptr = &desc->action;
    old = *old_ptr;
    if (old) {
        /*
         * Can't share interrupts unless both agree to and are
         * the same type (level, edge, polarity). So both flag
         * fields must have IRQF_SHARED set and the bits which
         * set the trigger type must match. Also all must
         * agree on ONESHOT.
         */
        if (!((old->flags & new->flags) & IRQF_SHARED) ||
            ((old->flags ^ new->flags) & IRQF_TRIGGER_MASK) ||
            ((old->flags ^ new->flags) & IRQF_ONESHOT))
            goto mismatch;

        /* All handlers must agree on per-cpuness */
        if ((old->flags & IRQF_PERCPU) !=
            (new->flags & IRQF_PERCPU))
            goto mismatch;

        /* add new interrupt at end of irq queue */
        do {
            /*
             * Or all existing action->thread_mask bits,
             * so we can find the next zero bit for this
             * new action.
             */
            thread_mask |= old->thread_mask;
            old_ptr = &old->next;
            old = *old_ptr;
        } while (old);
        shared = 1;
    }

    /*
     * Setup the thread mask for this irqaction for ONESHOT. For
     * !ONESHOT irqs the thread mask is 0 so we can avoid a
     * conditional in irq_wake_thread().
     */
    if (new->flags & IRQF_ONESHOT) {
        /*
         * Unlikely to have 32 resp 64 irqs sharing one line,
         * but who knows.
         */
        if (thread_mask == ~0UL) {
            ret = -EBUSY;
            goto out_mask;
        }
        /*
         * The thread_mask for the action is or'ed to
         * desc->thread_active to indicate that the
         * IRQF_ONESHOT thread handler has been woken, but not
         * yet finished. The bit is cleared when a thread
         * completes. When all threads of a shared interrupt
         * line have completed desc->threads_active becomes
         * zero and the interrupt line is unmasked. See
         * handle.c:irq_wake_thread() for further information.
         *
         * If no thread is woken by primary (hard irq context)
         * interrupt handlers, then desc->threads_active is
         * also checked for zero to unmask the irq line in the
         * affected hard irq flow handlers
         * (handle_[fasteoi|level]_irq).
         *
         * The new action gets the first zero bit of
         * thread_mask assigned. See the loop above which or's
         * all existing action->thread_mask bits.
         */
        new->thread_mask = 1 << ffz(thread_mask);

    } else if (new->handler == irq_default_primary_handler &&
           !(desc->irq_data.chip->flags & IRQCHIP_ONESHOT_SAFE)) {
        /*
         * The interrupt was requested with handler = NULL, so
         * we use the default primary handler for it. But it
         * does not have the oneshot flag set. In combination
         * with level interrupts this is deadly, because the
         * default primary handler just wakes the thread, then
         * the irq lines is reenabled, but the device still
         * has the level irq asserted. Rinse and repeat....
         *
         * While this works for edge type interrupts, we play
         * it safe and reject unconditionally because we can't
         * say for sure which type this interrupt really
         * has. The type flags are unreliable as the
         * underlying chip implementation can override them.
         */
        pr_err("Threaded irq requested with handler=NULL and !ONESHOT for irq %d\n",
               irq);
        ret = -EINVAL;
        goto out_mask;
    }

    if (!shared) {
        init_waitqueue_head(&desc->wait_for_threads);

        /* Setup the type (level, edge polarity) if configured: */
        if (new->flags & IRQF_TRIGGER_MASK) {
            ret = __irq_set_trigger(desc, irq,
                    new->flags & IRQF_TRIGGER_MASK);

            if (ret)
                goto out_mask;
        }

        desc->istate &= ~(IRQS_AUTODETECT | IRQS_SPURIOUS_DISABLED | \
                  IRQS_ONESHOT | IRQS_WAITING);
        irqd_clear(&desc->irq_data, IRQD_IRQ_INPROGRESS);

        if (new->flags & IRQF_PERCPU) {
            irqd_set(&desc->irq_data, IRQD_PER_CPU);
            irq_settings_set_per_cpu(desc);
        }

        if (new->flags & IRQF_ONESHOT)
            desc->istate |= IRQS_ONESHOT;

        if (irq_settings_can_autoenable(desc))
            irq_startup(desc, true);
        else
            /* Undo nested disables: */
            desc->depth = 1;

        /* Exclude IRQ from balancing if requested */
        if (new->flags & IRQF_NOBALANCING) {
            irq_settings_set_no_balancing(desc);
            irqd_set(&desc->irq_data, IRQD_NO_BALANCING);
        }

        /* Set default affinity mask once everything is setup */
        setup_affinity(irq, desc, mask);

    } else if (new->flags & IRQF_TRIGGER_MASK) {
        unsigned int nmsk = new->flags & IRQF_TRIGGER_MASK;
        unsigned int omsk = irq_settings_get_trigger_mask(desc);

        if (nmsk != omsk)
            /* hope the handler works with current  trigger mode */
            pr_warning("irq %d uses trigger mode %u; requested %u\n",
                   irq, nmsk, omsk);
    }

    new->irq = irq;
    *old_ptr = new;

    /* Reset broken irq detection when installing new handler */
    desc->irq_count = 0;
    desc->irqs_unhandled = 0;

    /*
     * Check whether we disabled the irq via the spurious handler
     * before. Reenable it and give it another chance.
     */
    if (shared && (desc->istate & IRQS_SPURIOUS_DISABLED)) {
        desc->istate &= ~IRQS_SPURIOUS_DISABLED;
        __enable_irq(desc, irq, false);
    }

    raw_spin_unlock_irqrestore(&desc->lock, flags);

    /*
     * Strictly no need to wake it up, but hung_task complains
     * when no hard interrupt wakes the thread up.
     */
    if (new->thread)
        wake_up_process(new->thread);

    register_irq_proc(irq, desc);
    new->dir = NULL;
    register_handler_proc(irq, new);
    free_cpumask_var(mask);

    return 0;

mismatch:
    if (!(new->flags & IRQF_PROBE_SHARED)) {
        pr_err("Flags mismatch irq %d. %08x (%s) vs. %08x (%s)\n",
               irq, new->flags, new->name, old->flags, old->name);
#ifdef CONFIG_DEBUG_SHIRQ
        dump_stack();
#endif
    }
    ret = -EBUSY;

out_mask:
    raw_spin_unlock_irqrestore(&desc->lock, flags);
    free_cpumask_var(mask);

out_thread:
    if (new->thread) {
        struct task_struct *t = new->thread;

        new->thread = NULL;
        kthread_stop(t);
        put_task_struct(t);
    }
out_mput:
    module_put(desc->owner);
    return ret;
}

int setup_irq(unsigned int irq, struct irqaction *act)
{
    int retval;
    struct irq_desc *desc = irq_to_desc(irq);

    if (WARN_ON(irq_settings_is_per_cpu_devid(desc)))
        return -EINVAL;
    chip_bus_lock(desc);
    retval = __setup_irq(irq, desc, act);
    chip_bus_sync_unlock(desc);

    return retval;
}
EXPORT_SYMBOL_GPL(setup_irq);

/*
 * Internal function to unregister an irqaction - used to free
 * regular and special interrupts that are part of the architecture.
 */
static struct irqaction *__free_irq(unsigned int irq, void *dev_id)
{
    struct irq_desc *desc = irq_to_desc(irq);
    struct irqaction *action, **action_ptr;
    unsigned long flags;

    WARN(in_interrupt(), "Trying to free IRQ %d from IRQ context!\n", irq);

    if (!desc)
        return NULL;

    raw_spin_lock_irqsave(&desc->lock, flags);

    /*
     * There can be multiple actions per IRQ descriptor, find the right
     * one based on the dev_id:
     */
    action_ptr = &desc->action;
    for (;;) {
        action = *action_ptr;

        if (!action) {
            WARN(1, "Trying to free already-free IRQ %d\n", irq);
            raw_spin_unlock_irqrestore(&desc->lock, flags);

            return NULL;
        }

        if (action->dev_id == dev_id)
            break;
        action_ptr = &action->next;
    }

    /* Found it - now remove it from the list of entries: */
    *action_ptr = action->next;

    /* If this was the last handler, shut down the IRQ line: */
    if (!desc->action)
        irq_shutdown(desc);

#ifdef CONFIG_SMP
    /* make sure affinity_hint is cleaned up */
    if (WARN_ON_ONCE(desc->affinity_hint))
        desc->affinity_hint = NULL;
#endif

    raw_spin_unlock_irqrestore(&desc->lock, flags);

    unregister_handler_proc(irq, action);

    /* Make sure it's not being used on another CPU: */
    synchronize_irq(irq);

#ifdef CONFIG_DEBUG_SHIRQ
    /*
     * It's a shared IRQ -- the driver ought to be prepared for an IRQ
     * event to happen even now it's being freed, so let's make sure that
     * is so by doing an extra call to the handler ....
     *
     * ( We do this after actually deregistering it, to make sure that a
     *   'real' IRQ doesn't run in * parallel with our fake. )
     */
    if (action->flags & IRQF_SHARED) {
        local_irq_save(flags);
        action->handler(irq, dev_id);
        local_irq_restore(flags);
    }
#endif

    if (action->thread) {
        kthread_stop(action->thread);
        put_task_struct(action->thread);
    }

    module_put(desc->owner);
    return action;
}

void remove_irq(unsigned int irq, struct irqaction *act)
{
    struct irq_desc *desc = irq_to_desc(irq);

    if (desc && !WARN_ON(irq_settings_is_per_cpu_devid(desc)))
        __free_irq(irq, act->dev_id);
}
EXPORT_SYMBOL_GPL(remove_irq);

void free_irq(unsigned int irq, void *dev_id)
{
    struct irq_desc *desc = irq_to_desc(irq);

    if (!desc || WARN_ON(irq_settings_is_per_cpu_devid(desc)))
        return;

#ifdef CONFIG_SMP
    if (WARN_ON(desc->affinity_notify))
        desc->affinity_notify = NULL;
#endif

    chip_bus_lock(desc);
    kfree(__free_irq(irq, dev_id));
    chip_bus_sync_unlock(desc);
}
EXPORT_SYMBOL(free_irq);

int request_threaded_irq(unsigned int irq, irq_handler_t handler,
             irq_handler_t thread_fn, unsigned long irqflags,
             const char *devname, void *dev_id)
{
    struct irqaction *action;
    struct irq_desc *desc;
    int retval;

    /*
     * Sanity-check: shared interrupts must pass in a real dev-ID,
     * otherwise we'll have trouble later trying to figure out
     * which interrupt is which (messes up the interrupt freeing
     * logic etc).
     */
    if ((irqflags & IRQF_SHARED) && !dev_id)
        return -EINVAL;

    desc = irq_to_desc(irq);
    if (!desc)
        return -EINVAL;

    if (!irq_settings_can_request(desc) ||
        WARN_ON(irq_settings_is_per_cpu_devid(desc)))
        return -EINVAL;

    if (!handler) {
        if (!thread_fn)
            return -EINVAL;
        handler = irq_default_primary_handler;
    }

    action = kzalloc(sizeof(struct irqaction), GFP_KERNEL);
    if (!action)
        return -ENOMEM;

    action->handler = handler;
    action->thread_fn = thread_fn;
    action->flags = irqflags;
    action->name = devname;
    action->dev_id = dev_id;

    chip_bus_lock(desc);
    retval = __setup_irq(irq, desc, action);
    chip_bus_sync_unlock(desc);

    if (retval)
        kfree(action);

#ifdef CONFIG_DEBUG_SHIRQ_FIXME
    if (!retval && (irqflags & IRQF_SHARED)) {
        /*
         * It's a shared IRQ -- the driver ought to be prepared for it
         * to happen immediately, so let's make sure....
         * We disable the irq to make sure that a 'real' IRQ doesn't
         * run in parallel with our fake.
         */
        unsigned long flags;

        disable_irq(irq);
        local_irq_save(flags);

        handler(irq, dev_id);

        local_irq_restore(flags);
        enable_irq(irq);
    }
#endif
    return retval;
}
EXPORT_SYMBOL(request_threaded_irq);

int request_any_context_irq(unsigned int irq, irq_handler_t handler,
                unsigned long flags, const char *name, void *dev_id)
{
    struct irq_desc *desc = irq_to_desc(irq);
    int ret;

    if (!desc)
        return -EINVAL;

    if (irq_settings_is_nested_thread(desc)) {
        ret = request_threaded_irq(irq, NULL, handler,
                       flags, name, dev_id);
        return !ret ? IRQC_IS_NESTED : ret;
    }

    ret = request_irq(irq, handler, flags, name, dev_id);
    return !ret ? IRQC_IS_HARDIRQ : ret;
}
EXPORT_SYMBOL_GPL(request_any_context_irq);

void enable_percpu_irq(unsigned int irq, unsigned int type)
{
    unsigned int cpu = smp_processor_id();
    unsigned long flags;
    struct irq_desc *desc = irq_get_desc_lock(irq, &flags, IRQ_GET_DESC_CHECK_PERCPU);

    if (!desc)
        return;

    type &= IRQ_TYPE_SENSE_MASK;
    if (type != IRQ_TYPE_NONE) {
        int ret;

        ret = __irq_set_trigger(desc, irq, type);

        if (ret) {
            WARN(1, "failed to set type for IRQ%d\n", irq);
            goto out;
        }
    }

    irq_percpu_enable(desc, cpu);
out:
    irq_put_desc_unlock(desc, flags);
}

void disable_percpu_irq(unsigned int irq)
{
    unsigned int cpu = smp_processor_id();
    unsigned long flags;
    struct irq_desc *desc = irq_get_desc_lock(irq, &flags, IRQ_GET_DESC_CHECK_PERCPU);

    if (!desc)
        return;

    irq_percpu_disable(desc, cpu);
    irq_put_desc_unlock(desc, flags);
}

/*
 * Internal function to unregister a percpu irqaction.
 */
static struct irqaction *__free_percpu_irq(unsigned int irq, void __percpu *dev_id)
{
    struct irq_desc *desc = irq_to_desc(irq);
    struct irqaction *action;
    unsigned long flags;

    WARN(in_interrupt(), "Trying to free IRQ %d from IRQ context!\n", irq);

    if (!desc)
        return NULL;

    raw_spin_lock_irqsave(&desc->lock, flags);

    action = desc->action;
    if (!action || action->percpu_dev_id != dev_id) {
        WARN(1, "Trying to free already-free IRQ %d\n", irq);
        goto bad;
    }

    if (!cpumask_empty(desc->percpu_enabled)) {
        WARN(1, "percpu IRQ %d still enabled on CPU%d!\n",
             irq, cpumask_first(desc->percpu_enabled));
        goto bad;
    }

    /* Found it - now remove it from the list of entries: */
    desc->action = NULL;

    raw_spin_unlock_irqrestore(&desc->lock, flags);

    unregister_handler_proc(irq, action);

    module_put(desc->owner);
    return action;

bad:
    raw_spin_unlock_irqrestore(&desc->lock, flags);
    return NULL;
}

void remove_percpu_irq(unsigned int irq, struct irqaction *act)
{
    struct irq_desc *desc = irq_to_desc(irq);

    if (desc && irq_settings_is_per_cpu_devid(desc))
        __free_percpu_irq(irq, act->percpu_dev_id);
}

void free_percpu_irq(unsigned int irq, void __percpu *dev_id)
{
    struct irq_desc *desc = irq_to_desc(irq);

    if (!desc || !irq_settings_is_per_cpu_devid(desc))
        return;

    chip_bus_lock(desc);
    kfree(__free_percpu_irq(irq, dev_id));
    chip_bus_sync_unlock(desc);
}

int setup_percpu_irq(unsigned int irq, struct irqaction *act)
{
    struct irq_desc *desc = irq_to_desc(irq);
    int retval;

    if (!desc || !irq_settings_is_per_cpu_devid(desc))
        return -EINVAL;
    chip_bus_lock(desc);
    retval = __setup_irq(irq, desc, act);
    chip_bus_sync_unlock(desc);

    return retval;
}

int request_percpu_irq(unsigned int irq, irq_handler_t handler,
               const char *devname, void __percpu *dev_id)
{
    struct irqaction *action;
    struct irq_desc *desc;
    int retval;

    if (!dev_id)
        return -EINVAL;

    desc = irq_to_desc(irq);
    if (!desc || !irq_settings_can_request(desc) ||
        !irq_settings_is_per_cpu_devid(desc))
        return -EINVAL;

    action = kzalloc(sizeof(struct irqaction), GFP_KERNEL);
    if (!action)
        return -ENOMEM;

    action->handler = handler;
    action->flags = IRQF_PERCPU | IRQF_NO_SUSPEND;
    action->name = devname;
    action->percpu_dev_id = dev_id;

    chip_bus_lock(desc);
    retval = __setup_irq(irq, desc, action);
    chip_bus_sync_unlock(desc);

    if (retval)
        kfree(action);

    return retval;
}