--- /dev/null
+/*
+ * 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;
+}
+EXPORT_SYMBOL_GPL(no_action);
+
+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);
+}
+
+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)
+{
+ struct pt_regs *regs = get_irq_regs();
+ u64 ip = regs ? instruction_pointer(regs) : 0;
+ irqreturn_t retval = IRQ_NONE;
+ unsigned int flags = 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:
+ flags |= action->flags;
+ break;
+
+ default:
+ break;
+ }
+
+ retval |= res;
+ action = action->next;
+ } while (action);
+
+#ifndef CONFIG_PREEMPT_RT_FULL
+ add_interrupt_randomness(irq, flags, ip);
+#else
+ desc->random_ip = ip;
+#endif
+
+ 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;
+}
Code Review / kvmfornfv.git / blobdiff