LXR linux/kernel/irq/resend.c

   1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 * Copyright (C) 1992, 1998-2006 Linus Torvalds, Ingo Molnar
   4 * Copyright (C) 2005-2006, Thomas Gleixner
   5 *
   6 * This file contains the IRQ-resend code
   7 *
   8 * If the interrupt is waiting to be processed, we try to re-run it.
   9 * We can't directly run it from here since the caller might be in an
  10 * interrupt-protected region. Not all irq controller chips can
  11 * retrigger interrupts at the hardware level, so in those cases
  12 * we allow the resending of IRQs via a tasklet.
  13 */
  14
  15#include <linux/irq.h>
  16#include <linux/module.h>
  17#include <linux/random.h>
  18#include <linux/interrupt.h>
  19
  20#include "internals.h"
  21
  22#ifdef CONFIG_HARDIRQS_SW_RESEND
  23
  24/* Bitmap to handle software resend of interrupts: */
  25static DECLARE_BITMAP(irqs_resend, IRQ_BITMAP_BITS);
  26
  27/*
  28 * Run software resends of IRQ's
  29 */
  30static void resend_irqs(unsigned long arg)
  31{
  32        struct irq_desc *desc;
  33        int irq;
  34
  35        while (!bitmap_empty(irqs_resend, nr_irqs)) {
  36                irq = find_first_bit(irqs_resend, nr_irqs);
  37                clear_bit(irq, irqs_resend);
  38                desc = irq_to_desc(irq);
  39                if (!desc)
  40                        continue;
  41                local_irq_disable();
  42                desc->handle_irq(desc);
  43                local_irq_enable();
  44        }
  45}
  46
  47/* Tasklet to handle resend: */
  48static DECLARE_TASKLET(resend_tasklet, resend_irqs, 0);
  49
  50static int irq_sw_resend(struct irq_desc *desc)
  51{
  52        unsigned int irq = irq_desc_get_irq(desc);
  53
  54        /*
  55         * Validate whether this interrupt can be safely injected from
  56         * non interrupt context
  57         */
  58        if (handle_enforce_irqctx(&desc->irq_data))
  59                return -EINVAL;
  60
  61        /*
  62         * If the interrupt is running in the thread context of the parent
  63         * irq we need to be careful, because we cannot trigger it
  64         * directly.
  65         */
  66        if (irq_settings_is_nested_thread(desc)) {
  67                /*
  68                 * If the parent_irq is valid, we retrigger the parent,
  69                 * otherwise we do nothing.
  70                 */
  71                if (!desc->parent_irq)
  72                        return -EINVAL;
  73                irq = desc->parent_irq;
  74        }
  75
  76        /* Set it pending and activate the softirq: */
  77        set_bit(irq, irqs_resend);
  78        tasklet_schedule(&resend_tasklet);
  79        return 0;
  80}
  81
  82#else
  83static int irq_sw_resend(struct irq_desc *desc)
  84{
  85        return -EINVAL;
  86}
  87#endif
  88
  89/*
  90 * IRQ resend
  91 *
  92 * Is called with interrupts disabled and desc->lock held.
  93 */
  94int check_irq_resend(struct irq_desc *desc, bool inject)
  95{
  96        int err = 0;
  97
  98        /*
  99         * We do not resend level type interrupts. Level type interrupts
 100         * are resent by hardware when they are still active. Clear the
 101         * pending bit so suspend/resume does not get confused.
 102         */
 103        if (irq_settings_is_level(desc)) {
 104                desc->istate &= ~IRQS_PENDING;
 105                return -EINVAL;
 106        }
 107
 108        if (desc->istate & IRQS_REPLAY)
 109                return -EBUSY;
 110
 111        if (!(desc->istate & IRQS_PENDING) && !inject)
 112                return 0;
 113
 114        desc->istate &= ~IRQS_PENDING;
 115
 116        if (!desc->irq_data.chip->irq_retrigger ||
 117            !desc->irq_data.chip->irq_retrigger(&desc->irq_data))
 118                err = irq_sw_resend(desc);
 119
 120        /* If the retrigger was successfull, mark it with the REPLAY bit */
 121        if (!err)
 122                desc->istate |= IRQS_REPLAY;
 123        return err;
 124}
 125
 126#ifdef CONFIG_GENERIC_IRQ_INJECTION
 127/**
 128 * irq_inject_interrupt - Inject an interrupt for testing/error injection
 129 * @irq:        The interrupt number
 130 *
 131 * This function must only be used for debug and testing purposes!
 132 *
 133 * Especially on x86 this can cause a premature completion of an interrupt
 134 * affinity change causing the interrupt line to become stale. Very
 135 * unlikely, but possible.
 136 *
 137 * The injection can fail for various reasons:
 138 * - Interrupt is not activated
 139 * - Interrupt is NMI type or currently replaying
 140 * - Interrupt is level type
 141 * - Interrupt does not support hardware retrigger and software resend is
 142 *   either not enabled or not possible for the interrupt.
 143 */
 144int irq_inject_interrupt(unsigned int irq)
 145{
 146        struct irq_desc *desc;
 147        unsigned long flags;
 148        int err;
 149
 150        /* Try the state injection hardware interface first */
 151        if (!irq_set_irqchip_state(irq, IRQCHIP_STATE_PENDING, true))
 152                return 0;
 153
 154        /* That failed, try via the resend mechanism */
 155        desc = irq_get_desc_buslock(irq, &flags, 0);
 156        if (!desc)
 157                return -EINVAL;
 158
 159        /*
 160         * Only try to inject when the interrupt is:
 161         *  - not NMI type
 162         *  - activated
 163         */
 164        if ((desc->istate & IRQS_NMI) || !irqd_is_activated(&desc->irq_data))
 165                err = -EINVAL;
 166        else
 167                err = check_irq_resend(desc, true);
 168
 169        irq_put_desc_busunlock(desc, flags);
 170        return err;
 171}
 172EXPORT_SYMBOL_GPL(irq_inject_interrupt);
 173#endif
 174