// SPDX-License-Identifier: GPL-2.0
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/*
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* Copyright (C) 1992, 1998-2004 Linus Torvalds, Ingo Molnar
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*
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* This file contains spurious interrupt handling.
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*/
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#include <linux/jiffies.h>
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#include <linux/irq.h>
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#include <linux/module.h>
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#include <linux/interrupt.h>
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#include <linux/moduleparam.h>
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#include <linux/timer.h>
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#include "internals.h"
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static int irqfixup __read_mostly;
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#define POLL_SPURIOUS_IRQ_INTERVAL (HZ/10)
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static void poll_spurious_irqs(struct timer_list *unused);
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static DEFINE_TIMER(poll_spurious_irq_timer, poll_spurious_irqs);
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static int irq_poll_cpu;
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static atomic_t irq_poll_active;
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/*
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* We wait here for a poller to finish.
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*
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* If the poll runs on this CPU, then we yell loudly and return
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* false. That will leave the interrupt line disabled in the worst
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* case, but it should never happen.
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*
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* We wait until the poller is done and then recheck disabled and
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* action (about to be disabled). Only if it's still active, we return
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* true and let the handler run.
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*/
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bool irq_wait_for_poll(struct irq_desc *desc)
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__must_hold(&desc->lock)
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{
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if (WARN_ONCE(irq_poll_cpu == smp_processor_id(),
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"irq poll in progress on cpu %d for irq %d\n",
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smp_processor_id(), desc->irq_data.irq))
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return false;
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#ifdef CONFIG_SMP
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do {
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raw_spin_unlock(&desc->lock);
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while (irqd_irq_inprogress(&desc->irq_data))
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cpu_relax();
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raw_spin_lock(&desc->lock);
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} while (irqd_irq_inprogress(&desc->irq_data));
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/* Might have been disabled in meantime */
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return !irqd_irq_disabled(&desc->irq_data) && desc->action;
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#else
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return false;
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#endif
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}
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/*
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* Recovery handler for misrouted interrupts.
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*/
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static int try_one_irq(struct irq_desc *desc, bool force)
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{
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irqreturn_t ret = IRQ_NONE;
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struct irqaction *action;
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raw_spin_lock(&desc->lock);
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/*
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* PER_CPU, nested thread interrupts and interrupts explicitly
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* marked polled are excluded from polling.
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*/
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if (irq_settings_is_per_cpu(desc) ||
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irq_settings_is_nested_thread(desc) ||
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irq_settings_is_polled(desc))
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goto out;
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/*
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* Do not poll disabled interrupts unless the spurious
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* disabled poller asks explicitly.
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*/
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if (irqd_irq_disabled(&desc->irq_data) && !force)
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goto out;
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/*
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* All handlers must agree on IRQF_SHARED, so we test just the
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* first.
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*/
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action = desc->action;
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if (!action || !(action->flags & IRQF_SHARED) ||
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(action->flags & __IRQF_TIMER))
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goto out;
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/* Already running on another processor */
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if (irqd_irq_inprogress(&desc->irq_data)) {
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/*
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* Already running: If it is shared get the other
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* CPU to go looking for our mystery interrupt too
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*/
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desc->istate |= IRQS_PENDING;
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goto out;
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}
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/* Mark it poll in progress */
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desc->istate |= IRQS_POLL_INPROGRESS;
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do {
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if (handle_irq_event(desc) == IRQ_HANDLED)
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ret = IRQ_HANDLED;
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/* Make sure that there is still a valid action */
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action = desc->action;
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} while ((desc->istate & IRQS_PENDING) && action);
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desc->istate &= ~IRQS_POLL_INPROGRESS;
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out:
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raw_spin_unlock(&desc->lock);
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return ret == IRQ_HANDLED;
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}
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static int misrouted_irq(int irq)
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{
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struct irq_desc *desc;
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int i, ok = 0;
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if (atomic_inc_return(&irq_poll_active) != 1)
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goto out;
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irq_poll_cpu = smp_processor_id();
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for_each_irq_desc(i, desc) {
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if (!i)
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continue;
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if (i == irq) /* Already tried */
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continue;
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if (try_one_irq(desc, false))
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ok = 1;
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}
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out:
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atomic_dec(&irq_poll_active);
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/* So the caller can adjust the irq error counts */
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return ok;
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}
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static void poll_spurious_irqs(struct timer_list *unused)
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{
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struct irq_desc *desc;
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int i;
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if (atomic_inc_return(&irq_poll_active) != 1)
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goto out;
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irq_poll_cpu = smp_processor_id();
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for_each_irq_desc(i, desc) {
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unsigned int state;
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if (!i)
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continue;
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/* Racy but it doesn't matter */
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state = desc->istate;
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barrier();
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if (!(state & IRQS_SPURIOUS_DISABLED))
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continue;
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local_irq_disable();
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try_one_irq(desc, true);
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local_irq_enable();
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}
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out:
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atomic_dec(&irq_poll_active);
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mod_timer(&poll_spurious_irq_timer,
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jiffies + POLL_SPURIOUS_IRQ_INTERVAL);
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}
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static inline int bad_action_ret(irqreturn_t action_ret)
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{
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unsigned int r = action_ret;
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if (likely(r <= (IRQ_HANDLED | IRQ_WAKE_THREAD)))
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return 0;
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return 1;
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}
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/*
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* If 99,900 of the previous 100,000 interrupts have not been handled
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* then assume that the IRQ is stuck in some manner. Drop a diagnostic
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* and try to turn the IRQ off.
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*
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* (The other 100-of-100,000 interrupts may have been a correctly
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* functioning device sharing an IRQ with the failing one)
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*/
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static void __report_bad_irq(struct irq_desc *desc, irqreturn_t action_ret)
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{
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unsigned int irq = irq_desc_get_irq(desc);
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struct irqaction *action;
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unsigned long flags;
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if (bad_action_ret(action_ret)) {
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printk(KERN_ERR "irq event %d: bogus return value %x\n",
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irq, action_ret);
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} else {
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printk(KERN_ERR "irq %d: nobody cared (try booting with "
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"the \"irqpoll\" option)\n", irq);
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}
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dump_stack();
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printk(KERN_ERR "handlers:\n");
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/*
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* We need to take desc->lock here. note_interrupt() is called
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* w/o desc->lock held, but IRQ_PROGRESS set. We might race
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* with something else removing an action. It's ok to take
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* desc->lock here. See synchronize_irq().
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*/
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raw_spin_lock_irqsave(&desc->lock, flags);
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for_each_action_of_desc(desc, action) {
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printk(KERN_ERR "[<%p>] %ps", action->handler, action->handler);
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if (action->thread_fn)
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printk(KERN_CONT " threaded [<%p>] %ps",
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action->thread_fn, action->thread_fn);
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printk(KERN_CONT "\n");
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}
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raw_spin_unlock_irqrestore(&desc->lock, flags);
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}
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static void report_bad_irq(struct irq_desc *desc, irqreturn_t action_ret)
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{
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static int count = 100;
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if (count > 0) {
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count--;
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__report_bad_irq(desc, action_ret);
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}
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}
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static inline int
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try_misrouted_irq(unsigned int irq, struct irq_desc *desc,
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irqreturn_t action_ret)
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{
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struct irqaction *action;
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if (!irqfixup)
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return 0;
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/* We didn't actually handle the IRQ - see if it was misrouted? */
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if (action_ret == IRQ_NONE)
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return 1;
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/*
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* But for 'irqfixup == 2' we also do it for handled interrupts if
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* they are marked as IRQF_IRQPOLL (or for irq zero, which is the
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* traditional PC timer interrupt.. Legacy)
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*/
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if (irqfixup < 2)
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return 0;
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if (!irq)
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return 1;
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/*
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* Since we don't get the descriptor lock, "action" can
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* change under us. We don't really care, but we don't
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* want to follow a NULL pointer. So tell the compiler to
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* just load it once by using a barrier.
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*/
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action = desc->action;
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barrier();
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return action && (action->flags & IRQF_IRQPOLL);
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}
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#define SPURIOUS_DEFERRED 0x80000000
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void note_interrupt(struct irq_desc *desc, irqreturn_t action_ret)
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{
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unsigned int irq;
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if (desc->istate & IRQS_POLL_INPROGRESS ||
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irq_settings_is_polled(desc))
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return;
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if (bad_action_ret(action_ret)) {
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report_bad_irq(desc, action_ret);
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return;
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}
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/*
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* We cannot call note_interrupt from the threaded handler
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* because we need to look at the compound of all handlers
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* (primary and threaded). Aside of that in the threaded
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* shared case we have no serialization against an incoming
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* hardware interrupt while we are dealing with a threaded
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* result.
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*
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* So in case a thread is woken, we just note the fact and
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* defer the analysis to the next hardware interrupt.
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*
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* The threaded handlers store whether they successfully
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* handled an interrupt and we check whether that number
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* changed versus the last invocation.
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*
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* We could handle all interrupts with the delayed by one
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* mechanism, but for the non forced threaded case we'd just
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* add pointless overhead to the straight hardirq interrupts
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* for the sake of a few lines less code.
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*/
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if (action_ret & IRQ_WAKE_THREAD) {
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/*
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* There is a thread woken. Check whether one of the
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* shared primary handlers returned IRQ_HANDLED. If
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* not we defer the spurious detection to the next
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* interrupt.
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*/
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if (action_ret == IRQ_WAKE_THREAD) {
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int handled;
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/*
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* We use bit 31 of thread_handled_last to
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* denote the deferred spurious detection
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* active. No locking necessary as
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* thread_handled_last is only accessed here
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* and we have the guarantee that hard
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* interrupts are not reentrant.
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*/
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if (!(desc->threads_handled_last & SPURIOUS_DEFERRED)) {
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desc->threads_handled_last |= SPURIOUS_DEFERRED;
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return;
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}
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/*
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* Check whether one of the threaded handlers
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* returned IRQ_HANDLED since the last
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* interrupt happened.
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*
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* For simplicity we just set bit 31, as it is
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* set in threads_handled_last as well. So we
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* avoid extra masking. And we really do not
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* care about the high bits of the handled
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* count. We just care about the count being
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* different than the one we saw before.
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*/
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handled = atomic_read(&desc->threads_handled);
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handled |= SPURIOUS_DEFERRED;
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if (handled != desc->threads_handled_last) {
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action_ret = IRQ_HANDLED;
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/*
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* Note: We keep the SPURIOUS_DEFERRED
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* bit set. We are handling the
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* previous invocation right now.
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* Keep it for the current one, so the
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* next hardware interrupt will
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* account for it.
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*/
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desc->threads_handled_last = handled;
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} else {
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/*
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* None of the threaded handlers felt
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* responsible for the last interrupt
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*
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* We keep the SPURIOUS_DEFERRED bit
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* set in threads_handled_last as we
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* need to account for the current
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* interrupt as well.
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*/
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action_ret = IRQ_NONE;
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}
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} else {
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/*
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* One of the primary handlers returned
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* IRQ_HANDLED. So we don't care about the
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* threaded handlers on the same line. Clear
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* the deferred detection bit.
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*
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* In theory we could/should check whether the
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* deferred bit is set and take the result of
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* the previous run into account here as
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* well. But it's really not worth the
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* trouble. If every other interrupt is
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* handled we never trigger the spurious
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* detector. And if this is just the one out
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* of 100k unhandled ones which is handled
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* then we merily delay the spurious detection
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* by one hard interrupt. Not a real problem.
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*/
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desc->threads_handled_last &= ~SPURIOUS_DEFERRED;
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}
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}
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if (unlikely(action_ret == IRQ_NONE)) {
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/*
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* If we are seeing only the odd spurious IRQ caused by
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* bus asynchronicity then don't eventually trigger an error,
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* otherwise the counter becomes a doomsday timer for otherwise
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* working systems
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*/
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if (time_after(jiffies, desc->last_unhandled + HZ/10))
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desc->irqs_unhandled = 1;
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else
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desc->irqs_unhandled++;
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desc->last_unhandled = jiffies;
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}
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irq = irq_desc_get_irq(desc);
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if (unlikely(try_misrouted_irq(irq, desc, action_ret))) {
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int ok = misrouted_irq(irq);
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if (action_ret == IRQ_NONE)
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desc->irqs_unhandled -= ok;
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}
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desc->irq_count++;
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if (likely(desc->irq_count < 100000))
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return;
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desc->irq_count = 0;
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if (unlikely(desc->irqs_unhandled > 99900)) {
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/*
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* The interrupt is stuck
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*/
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__report_bad_irq(desc, action_ret);
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/*
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* Now kill the IRQ
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*/
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printk(KERN_EMERG "Disabling IRQ #%d\n", irq);
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desc->istate |= IRQS_SPURIOUS_DISABLED;
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desc->depth++;
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irq_disable(desc);
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mod_timer(&poll_spurious_irq_timer,
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jiffies + POLL_SPURIOUS_IRQ_INTERVAL);
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}
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desc->irqs_unhandled = 0;
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}
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bool noirqdebug __read_mostly;
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int noirqdebug_setup(char *str)
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{
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noirqdebug = 1;
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printk(KERN_INFO "IRQ lockup detection disabled\n");
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return 1;
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}
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__setup("noirqdebug", noirqdebug_setup);
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module_param(noirqdebug, bool, 0644);
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MODULE_PARM_DESC(noirqdebug, "Disable irq lockup detection when true");
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static int __init irqfixup_setup(char *str)
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{
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#ifdef CONFIG_PREEMPT_RT
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pr_warn("irqfixup boot option not supported w/ CONFIG_PREEMPT_RT\n");
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return 1;
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#endif
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irqfixup = 1;
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printk(KERN_WARNING "Misrouted IRQ fixup support enabled.\n");
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printk(KERN_WARNING "This may impact system performance.\n");
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return 1;
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}
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__setup("irqfixup", irqfixup_setup);
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module_param(irqfixup, int, 0644);
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static int __init irqpoll_setup(char *str)
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{
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#ifdef CONFIG_PREEMPT_RT
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pr_warn("irqpoll boot option not supported w/ CONFIG_PREEMPT_RT\n");
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return 1;
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#endif
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irqfixup = 2;
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printk(KERN_WARNING "Misrouted IRQ fixup and polling support "
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"enabled\n");
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printk(KERN_WARNING "This may significantly impact system "
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"performance\n");
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return 1;
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}
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__setup("irqpoll", irqpoll_setup);
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