ClabureDB: Classified Bug-Reports Database

  /*
   * 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 "internals.h"
 
 /**
  * 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);
 
 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
         }
 };
 
 /*
  * 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
/*
 * lockdep: we want to handle all irq_desc locks as a single lock-class:
 */
static struct lock_class_key irq_desc_lock_class;

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);
}
#endif