Re: [PATCH v5 1/5] bug/kunit: Core support for suppressing warning backtraces

[Kees Cook]

On May 31, 2025 3:23:04 AM PDT, Peter Zijlstra <peterz at infradead.org> wrote:
>On Fri, May 30, 2025 at 10:48:47AM -0700, Kees Cook wrote:
>> On Fri, May 30, 2025 at 04:01:40PM +0200, Peter Zijlstra wrote:
>> > I'm not really concerned with performance here, but more with the size
>> > of the code emitted by WARN_ONCE(). There are a *ton* of WARN sites,
>> > while only one report_bug() and printk().
>> > 
>> > The really offensive thing is that this is for a feature most nobody
>> > will ever need :/
>> 
>> Well, it won't be enabled often -- this reminds me of ftrace: it needs
>> to work, but it'll be off most of the time.
>
>Well, ftrace is useful, but when would I *ever* care about this stuff? I
>can't operate kunit, don't give a crap about kunit, and if I were to
>magically run it, I would be more than capable of ignoring WARNs.

It's not for you, then. :) I can't operate ftrace, but I use kunit almost daily. Ignoring WARNs makes this much nicer, and especially for CIs.

>Cleaned it up a little bit... I'll add some comments on later :-)
>
>I also need to go fix WARN_ONCE(), at least for the n<=2 cases that can
>use BUGFLAG_ONCE now.

Cool! I'll expand the WARN tests in LKDTM so we can get wider behavioral and architectural coverage.

-Kees


-- 
Kees Cook