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genirq: Add support for warning on long-running interrupt handlers

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Introduce a mechanism to detect and warn about prolonged interrupt handlers.
With a new command-line parameter (irqhandler.duration_warn_us=), users can
configure the duration threshold in microseconds when a warning in such
format should be emitted:

"[CPU14] long duration of IRQ[159:bad_irq_handler [long_irq]], took: 1330 us"

The implementation uses local_clock() to measure the execution duration of the
generic IRQ per-CPU event handler.

Signed-off-by: Wladislav Wiebe <wladislav.wiebe@nokia.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Jiri Slaby <jirislaby@kernel.org>
Link: https://lore.kernel.org/all/20250804093525.851-1-wladislav.wiebe@nokia.com
This commit is contained in:
Wladislav Wiebe
2025-08-04 11:35:25 +02:00
committed by Thomas Gleixner
parent 55b48e23f5
commit 673f1244b3
2 changed files with 53 additions and 1 deletions
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5
Documentation/admin-guide/kernel-parameters.txt
View File

@@ -2606,6 +2606,11 @@
for it. Intended to get systems with badly broken
firmware running.
irqhandler.duration_warn_us= [KNL]
Warn if an IRQ handler exceeds the specified duration
threshold in microseconds. Useful for identifying
long-running IRQs in the system.
irqpoll [HW]
When an interrupt is not handled search all handlers
for it. Also check all handlers each timer

49
kernel/irq/handle.c
View File

@@ -136,6 +136,44 @@ void __irq_wake_thread(struct irq_desc *desc, struct irqaction *action)
wake_up_process(action->thread);
}
static DEFINE_STATIC_KEY_FALSE(irqhandler_duration_check_enabled);
static u64 irqhandler_duration_threshold_ns __ro_after_init;
static int __init irqhandler_duration_check_setup(char *arg)
{
unsigned long val;
int ret;
ret = kstrtoul(arg, 0, &val);
if (ret) {
pr_err("Unable to parse irqhandler.duration_warn_us setting: ret=%d\n", ret);
return 0;
}
if (!val) {
pr_err("Invalid irqhandler.duration_warn_us setting, must be > 0\n");
return 0;
}
irqhandler_duration_threshold_ns = val * 1000;
static_branch_enable(&irqhandler_duration_check_enabled);
return 1;
}
__setup("irqhandler.duration_warn_us=", irqhandler_duration_check_setup);
static inline void irqhandler_duration_check(u64 ts_start, unsigned int irq,
const struct irqaction *action)
{
u64 delta_ns = local_clock() - ts_start;
if (unlikely(delta_ns > irqhandler_duration_threshold_ns)) {
pr_warn_ratelimited("[CPU%u] long duration of IRQ[%u:%ps], took: %llu us\n",
smp_processor_id(), irq, action->handler,
div_u64(delta_ns, NSEC_PER_USEC));
}
}
irqreturn_t __handle_irq_event_percpu(struct irq_desc *desc)
{
irqreturn_t retval = IRQ_NONE;
@@ -155,7 +193,16 @@ irqreturn_t __handle_irq_event_percpu(struct irq_desc *desc)
lockdep_hardirq_threaded();
trace_irq_handler_entry(irq, action);
res = action->handler(irq, action->dev_id);
if (static_branch_unlikely(&irqhandler_duration_check_enabled)) {
u64 ts_start = local_clock();
res = action->handler(irq, action->dev_id);
irqhandler_duration_check(ts_start, irq, action);
} else {
res = action->handler(irq, action->dev_id);
}
trace_irq_handler_exit(irq, action, res);
if (WARN_ONCE(!irqs_disabled(),"irq %u handler %pS enabled interrupts\n",