linux/kernel/irq/resend.c

// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (C) 1992, 1998-2006 Linus Torvalds, Ingo Molnar
 * Copyright (C) 2005-2006, Thomas Gleixner
 *
 * This file contains the IRQ-resend code
 *
 * If the interrupt is waiting to be processed, we try to re-run it.
 * We can't directly run it from here since the caller might be in an
 * interrupt-protected region. Not all irq controller chips can
 * retrigger interrupts at the hardware level, so in those cases
 * we allow the resending of IRQs via a tasklet.
 */

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

#include "internals.h"

#ifdef CONFIG_HARDIRQS_SW_RESEND

/* hlist_head to handle software resend of interrupts: */
static HLIST_HEAD(irq_resend_list);
static DEFINE_RAW_SPINLOCK(irq_resend_lock);

/*
 * Run software resends of IRQ's
 */
static void resend_irqs(struct tasklet_struct *unused)
{ … }

/* Tasklet to handle resend: */
static DECLARE_TASKLET(resend_tasklet, resend_irqs);

static int irq_sw_resend(struct irq_desc *desc)
{ … }

void clear_irq_resend(struct irq_desc *desc)
{ … }

void irq_resend_init(struct irq_desc *desc)
{ … }
#else
void clear_irq_resend(struct irq_desc *desc) {}
void irq_resend_init(struct irq_desc *desc) {}

static int irq_sw_resend(struct irq_desc *desc)
{
	return -EINVAL;
}
#endif

static int try_retrigger(struct irq_desc *desc)
{ … }

/*
 * IRQ resend
 *
 * Is called with interrupts disabled and desc->lock held.
 */
int check_irq_resend(struct irq_desc *desc, bool inject)
{ … }

#ifdef CONFIG_GENERIC_IRQ_INJECTION
/**
 * irq_inject_interrupt - Inject an interrupt for testing/error injection
 * @irq:	The interrupt number
 *
 * This function must only be used for debug and testing purposes!
 *
 * Especially on x86 this can cause a premature completion of an interrupt
 * affinity change causing the interrupt line to become stale. Very
 * unlikely, but possible.
 *
 * The injection can fail for various reasons:
 * - Interrupt is not activated
 * - Interrupt is NMI type or currently replaying
 * - Interrupt is level type
 * - Interrupt does not support hardware retrigger and software resend is
 *   either not enabled or not possible for the interrupt.
 */
int irq_inject_interrupt(unsigned int irq)
{ … }
EXPORT_SYMBOL_GPL(…);
#endif