/* * 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_thandle_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;}