diff options
Diffstat (limited to 'kernel/irq/handle.c')
| -rw-r--r-- | kernel/irq/handle.c | 197 |
1 files changed, 197 insertions, 0 deletions
diff --git a/kernel/irq/handle.c b/kernel/irq/handle.c new file mode 100644 index 00000000..bdb18032 --- /dev/null +++ b/kernel/irq/handle.c @@ -0,0 +1,197 @@ +/* + * 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; +} |