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