linux-kernel - Re: [PATCH v4] genirq: add support for warning on long-running IRQ handlers

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <0d0393d0-d913-4595-86b2-59cbaf0dd076@nokia.com>
Date: Mon, 4 Aug 2025 11:47:34 +0200
From: Wladislav Wiebe <wladislav.wiebe@...ia.com>
To: Jiri Slaby <jirislaby@...nel.org>, tglx@...utronix.de, corbet@....net
Cc: akpm@...ux-foundation.org, paulmck@...nel.org, rostedt@...dmis.org,
 Neeraj.Upadhyay@....com, david@...hat.com, bp@...en8.de, arnd@...db.de,
 fvdl@...gle.com, linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
 peterz@...radead.org
Subject: Re: [PATCH v4] genirq: add support for warning on long-running IRQ
 handlers


On 31/07/2025 09:46, Jiri Slaby wrote:
>
>
> On 24. 07. 25, 17:50, Wladislav Wiebe wrote:
>> Introduce a mechanism to detect and warn about prolonged IRQ 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.
>
>
> This version LGTM
>
> Reviewed-by: Jiri Slaby <jirislaby@...nel.org>

Thanks a lot!

>
>> --- a/kernel/irq/handle.c
>> +++ b/kernel/irq/handle.c
> ...
>> +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,
>> +                                 delta_ns >> 10);
>
> Only that: would the division matter in here? Or print ns? But feel free
> to ignore this.

In principle one could think when the paramater interface is provided in microseconds,
the duration print might be in the same resolution - hmm.

However, for the division part I have no objection going with
precise devision as we are kind of no longer in the "fast-path", hence v5 prepared:
https://lore.kernel.org/lkml/20250804093525.851-1-wladislav.wiebe@nokia.com/

Thank you
- W.W.