path: root/kernel/irq/manage.c

/*
 * linux/kernel/irq/manage.c
 *
 * Copyright (C) 1992, 1998-2006 Linus Torvalds, Ingo Molnar
 * Copyright (C) 2005-2006 Thomas Gleixner
 *
 * This file contains driver APIs to the irq subsystem.
 */

#include <linux/irq.h>
#include <linux/kthread.h>
#include <linux/module.h>
#include <linux/random.h>
#include <linux/interrupt.h>
#include <linux/slab.h>
#include <linux/sched.h>

#include "internals.h"

/**
 *	synchronize_irq - wait for pending IRQ handlers (on other CPUs)
 *	@irq: interrupt number to wait for
 *
 *	This function waits for any pending IRQ handlers for this interrupt
 *	to complete before returning. If you use this function while
 *	holding a resource the IRQ handler may need you will deadlock.
 *
 *	This function may be called - with care - from IRQ context.
 */
void synchronize_irq(unsigned int irq)
{
	struct irq_desc *desc = irq_to_desc(irq);
	unsigned int status;

	if (!desc)
		return;

	do {
		unsigned long flags;

		/*
		 * Wait until we're out of the critical section.  This might
		 * give the wrong answer due to the lack of memory barriers.
		 */
		while (desc->status & IRQ_INPROGRESS)
			cpu_relax();

		/* Ok, that indicated we're done: double-check carefully. */
		raw_spin_lock_irqsave(&desc->lock, flags);
		status = desc->status;
		raw_spin_unlock_irqrestore(&desc->lock, flags);

		/* Oops, that failed? */
	} while (status & IRQ_INPROGRESS);

	/*
	 * We made sure that no hardirq handler is running. Now verify
	 * that no threaded handlers are active.
	 */
	wait_event(desc->wait_for_threads, !atomic_read(&desc->threads_active));
}
EXPORT_SYMBOL(synchronize_irq);

#ifdef CONFIG_SMP
cpumask_var_t irq_default_affinity;

/**
 *	irq_can_set_affinity - Check if the affinity of a given irq can be set
 *	@irq:		Interrupt to check
 *
 */
int irq_can_set_affinity(unsigned int irq)
{
	struct irq_desc *desc = irq_to_desc(irq);

	if (CHECK_IRQ_PER_CPU(desc->status) || !desc->chip ||
	    !desc->chip->set_affinity)
		return 0;

	return 1;
}

/**
 *	irq_set_thread_affinity - Notify irq threads to adjust affinity
 *	@desc:		irq descriptor which has affitnity changed
 *
 *	We just set IRQTF_AFFINITY and delegate the affinity setting
 *	to the interrupt thread itself. We can not call
 *	set_cpus_allowed_ptr() here as we hold desc->lock and this
 *	code can be called from hard interrupt context.
 */
void irq_set_thread_affinity(struct irq_desc *desc)
{
	struct irqaction *action = desc->action;

	while (action) {
		if (action->thread)
			set_bit(IRQTF_AFFINITY, &action->thread_flags);
		action = action->next;
	}
}

/**
 *	irq_set_affinity - Set the irq affinity of a given irq
 *	@irq:		Interrupt to set affinity
 *	@cpumask:	cpumask
 *
 */
int irq_set_affinity(unsigned int irq, const struct cpumask *cpumask)
{
	struct irq_desc *desc = irq_to_desc(irq);
	unsigned long flags;

	if (!desc->chip->set_affinity)
		return -EINVAL;

	raw_spin_lock_irqsave(&desc->lock, flags);

#ifdef CONFIG_GENERIC_PENDING_IRQ
	if (desc->status & IRQ_MOVE_PCNTXT) {
		if (!desc->chip->set_affinity(irq, cpumask)) {
			cpumask_copy(desc->affinity, cpumask);
			irq_set_thread_affinity(desc);
		}
	}
	else {
		desc->status |= IRQ_MOVE_PENDING;
		cpumask_copy(desc->pending_mask, cpumask);
	}
#else
	if (!desc->chip->set_affinity(irq, cpumask)) {
		cpumask_copy(desc->affinity, cpumask);
		irq_set_thread_affinity(desc);
	}
#endif
	desc->status |= IRQ_AFFINITY_SET;
	raw_spin_unlock_irqrestore(&desc->lock, flags);
	return 0;
}

#ifndef CONFIG_AUTO_IRQ_AFFINITY
/*
 * Generic version of the affinity autoselector.
 */
static int setup_affinity(unsigned int irq, struct irq_desc *desc)
{
	if (!irq_can_set_affinity(irq))
		return 0;

	/*
	 * Preserve an userspace affinity setup, but make sure that
	 * one of the targets is online.
	 */
	if (desc->status & (IRQ_AFFINITY_SET | IRQ_NO_BALANCING)) {
		if (cpumask_any_and(desc->affinity, cpu_online_mask)
		    < nr_cpu_ids)
			goto set_affinity;
		else
			desc->status &= ~IRQ_AFFINITY_SET;
	}

	cpumask_and(desc->affinity, cpu_online_mask, irq_default_affinity);
set_affinity:
	desc->chip->set_affinity(irq,