linux-kernel - Re: [PATCH v2] ww_mutex: convert self-test to KUnit

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Message-ID: <CAJ-ks9kG6g8v7ADJkpuwekg_87iDVq-hPcYR+Oobrrjb-a8hfg@mail.gmail.com>
Date: Fri, 14 Feb 2025 07:37:47 -0500
From: Tamir Duberstein <tamird@...il.com>
To: Peter Zijlstra <peterz@...radead.org>
Cc: David Gow <davidgow@...gle.com>, Ingo Molnar <mingo@...hat.com>, Will Deacon <will@...nel.org>, 
	Boqun Feng <boqun.feng@...il.com>, Waiman Long <longman@...hat.com>, 
	Andrew Morton <akpm@...ux-foundation.org>, Shuah Khan <shuah@...nel.org>, 
	Nathan Chancellor <nathan@...nel.org>, Nick Desaulniers <ndesaulniers@...gle.com>, 
	Bill Wendling <morbo@...gle.com>, Justin Stitt <justinstitt@...gle.com>, 
	Dan Carpenter <dan.carpenter@...aro.org>, linux-kernel@...r.kernel.org, 
	linux-kselftest@...r.kernel.org, llvm@...ts.linux.dev
Subject: Re: [PATCH v2] ww_mutex: convert self-test to KUnit

On Fri, Feb 14, 2025 at 4:48 AM Peter Zijlstra <peterz@...radead.org> wrote:
>
> On Thu, Feb 13, 2025 at 10:42:24AM -0500, Tamir Duberstein wrote:
> > On Thu, Feb 13, 2025 at 6:59 AM Peter Zijlstra <peterz@...radead.org> wrote:
> > >
> > > On Thu, Feb 13, 2025 at 06:40:20AM -0500, Tamir Duberstein wrote:
> > > > Convert this unit test to a KUnit test. This allows the test to benefit
> > > > from the KUnit tooling. Note that care is taken to avoid test-ending
> > > > assertions in worker threads, which is unsafe in KUnit (and wasn't done
> > > > before this change either).
> > >
> > > So this was something simple, and now I need to know how to operate this
> > > kunit nonsense :-(
> > >
> > > How is that an improvement?
> >
> > Hi Peter,
> >
> > David enumerated some of the benefits of KUnit in another
> > thread: https://lore.kernel.org/all/CABVgOS=KZrM2dWyp1HzVS0zh7vquLxmTY2T2Ti53DQADrW+sJg@mail.gmail.com/.
> >
> > My personal reason for preferring KUnit is that it's much easier to
> > run from userspace; the tooling takes care of building, starting the
> > VM, running the tests, and producing a human-friendly report.
>
> Wait what -- you have to run a VM just to use Kunit? That's a hard pass.
>
> If I can't simply run it natively on my test box, its a no go. And it
> using python also don't help, you shouldn't be needing that to load a
> module.

The tooling I mention is all optional. You can still use modprobe to
run the test as a module or at boot. In this case you'd set:

CONFIG_KUNIT=y
CONFIG_WW_MUTEX_KUNIT_TEST=m

and then run the test via:

```
modprobe ww_mutex_kunit
```

or to run at boot:

CONFIG_KUNIT=y
CONFIG_WW_MUTEX_KUNIT_TEST=y

Link: https://www.kernel.org/doc/html/latest/dev-tools/kunit/running_tips.html#running-built-in-tests
Link: https://www.kernel.org/doc/html/latest/dev-tools/kunit/running_tips.html#running-tests-as-modules