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/*
* 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/random.h>
#include <linux/sched.h>
#include <linux/interrupt.h>
#include <linux/kernel_stat.h>
#include <trace/events/irq.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);
}
/*
* 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);
}
static void irq_wake_thread(struct irq_desc *desc, struct irqaction *action)
{
/*
* In case the thread crashed and was killed we just pretend that
* we handled the interrupt. The hardirq handler has disabled the
* device interrupt, so no irq storm is lurking.
*/
if (action->thread->flags & PF_EXITING)
return;
/*
* Wake up the handler thread for this action. If the
* RUNTHREAD bit is already set, nothing to do.
*/
if (test_and_set_bit(IRQTF_RUNTHREAD, &action->thread_flags))
return;
/*
* It's safe to OR the mask lockless here. We have only two
* places which write to threads_oneshot: This code and the
* irq thread.
*
* This code is the hard irq context and can never run on two
* cpus in parallel. If it ever does we have more serious
* problems than this bitmask.
*
* The irq threads of this irq which clear their "running" bit
* in threads_oneshot are serialized via desc->lock against
* each other and they are serialized against this code by
* IRQS_INPROGRESS.
*
* Hard irq handler:
*
* spin_lock(desc->lock);
* desc->state |= IRQS_INPROGRESS;
* spin_unlock(desc->lock);
* set_bit(IRQTF_RUNTHREAD, &action->thread_flags);
* desc->threads_oneshot |= mask;
* spin_lock(desc->lock);
* desc->state &= ~IRQS_INPROGRESS;
* spin_unlock(desc->lock);
*
* irq thread:
*
* again:
* spin_lock(desc->lock);
* if (desc->state & IRQS_INPROGRESS) {
* spin_unlock(desc->lock);
* while(desc->state & IRQS_INPROGRESS)
* cpu_relax();
* goto again;
* }
* if (!test_bit(IRQTF_RUNTHREAD, &action->thread_flags))
* desc->threads_oneshot &= ~mask;
* spin_unlock(desc->lock);
*
* So either the thread waits for us to clear IRQS_INPROGRESS
* or we are waiting in the flow handler for desc->lock to be
* released before we reach this point. The thread also checks
* IRQTF_RUNTHREAD under desc->lock. If set it leaves
* threads_oneshot untouched and runs the thread another time.
*/
desc->threads_oneshot |= action->thread_mask;
/*
* We increment the threads_active counter in case we wake up
* the irq thread. The irq thread decrements the counter when
* it returns from the handler or in the exit path and wakes
* up waiters which are stuck in synchronize_irq() when the
* active count becomes zero. synchronize_irq() is serialized
* against this code (hard irq handler) via IRQS_INPROGRESS
* like the finalize_oneshot() code. See comment above.
*/
atomic_inc(&desc->threads_active);
wake_up_process(action->thread);
}
irqreturn_t
handle_irq_event_percpu(struct irq_desc *desc, struct irqaction *action)
{
irqreturn_t retval = IRQ_NONE;
unsigned int random = 0, irq = desc->irq_data.irq;
do {
irqreturn_t res;
trace_irq_handler_entry(irq, action);
res = action->handler(irq, action->dev_id);
trace_irq_handler_exit(irq, action, res);
if (WARN_ONCE(!irqs_disabled(),"irq %u handler %pF enabled interrupts\n",
irq, action->handler))
local_irq_disable();
switch (res) {
case IRQ_WAKE_THREAD:
/*
* 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;
}
irq_wake_thread(desc, action);
/* Fall through to add to randomness */
case IRQ_HANDLED:
random |= action->flags;
break;
default:
break;
}
retval |= res;
action = action->next;
} while (action);
if (random & IRQF_SAMPLE_RANDOM)
add_interrupt_randomness(irq);
if (!noirqdebug)
note_interrupt(irq, desc, retval);
return retval;
}
irqreturn_t handle_irq_event(struct irq_desc *desc)
{
struct irqaction *action = desc->action;
irqreturn_t ret;
desc->istate &= ~IRQS_PENDING;
irqd_set(&desc->irq_data, IRQD_IRQ_INPROGRESS);
raw_spin_unlock(&desc->lock);
ret = handle_irq_event_percpu(desc, action);
raw_spin_lock(&desc->lock);
irqd_clear(&desc->irq_data, IRQD_IRQ_INPROGRESS);
return ret;
}
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