linux-kernel - Re: [PATCH v5 1/3] printf: convert self-test to KUnit

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Message-ID: <Z8sYOm4qovtdOSI7@pathway.suse.cz>
Date: Fri, 7 Mar 2025 17:00:58 +0100
From: Petr Mladek <pmladek@...e.com>
To: Tamir Duberstein <tamird@...il.com>
Cc: Arpitha Raghunandan <98.arpi@...il.com>,
	David Gow <davidgow@...gle.com>,
	Steven Rostedt <rostedt@...dmis.org>,
	Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
	Rasmus Villemoes <linux@...musvillemoes.dk>,
	Sergey Senozhatsky <senozhatsky@...omium.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Shuah Khan <shuah@...nel.org>, Jonathan Corbet <corbet@....net>,
	Geert Uytterhoeven <geert@...ux-m68k.org>,
	Madhavan Srinivasan <maddy@...ux.ibm.com>,
	Michael Ellerman <mpe@...erman.id.au>,
	Nicholas Piggin <npiggin@...il.com>,
	Christophe Leroy <christophe.leroy@...roup.eu>,
	Naveen N Rao <naveen@...nel.org>,
	Brendan Higgins <brendan.higgins@...ux.dev>,
	linux-kernel@...r.kernel.org, linux-kselftest@...r.kernel.org,
	linux-doc@...r.kernel.org, linux-m68k@...ts.linux-m68k.org,
	linuxppc-dev@...ts.ozlabs.org
Subject: Re: [PATCH v5 1/3] printf: convert self-test to KUnit

On Thu 2025-03-06 09:25:43, Tamir Duberstein wrote:
> On Thu, Mar 6, 2025 at 7:25 AM Petr Mladek <pmladek@...e.com> wrote:
> >
> > On Fri 2025-02-21 15:34:30, Tamir Duberstein wrote:
> > > Convert the printf() self-test to a KUnit test.
> > >
> > > In the interest of keeping the patch reasonably-sized this doesn't
> > > refactor the tests into proper parameterized tests - it's all one big
> > > test case.
> > >
> > > --- a/lib/test_printf.c
> > > +++ b/lib/tests/printf_kunit.c
> > > @@ -57,52 +58,50 @@ do_test(int bufsize, const char *expect, int elen,
> > >       va_end(aq);
> > >
> > >       if (ret != elen) {
> > > -             pr_warn("vsnprintf(buf, %d, \"%s\", ...) returned %d, expected %d\n",
> > > +             tc_fail("vsnprintf(buf, %d, \"%s\", ...) returned %d, expected %d",
> >
> > 1. It looks a bit strange that the 1st patch replaces pr_warn() with
> >    tc_fail() which hides KUNIT_FAIL().
> >
> >    And the 2nd patch replaces tc_fail() with KUNIT_FAIL().
> >
> >    It looks like a non-necessary churn.
> >
> >    It would be better to avoid the temporary "tc_fail" and swith to
> >    KUNIT_FAIL() already in this patch.
> >
> >    I did not find any comment about this in the earier versions of the
> >    patchset.
> >
> >    Is it just a result of the evolution of the patchset or
> >    is there any motivation for this?
> 
> The motivation was to keep the width of the macro the same in this
> first patch for ease of review, particularly in the 7 instances where
> the invocation wraps to a second line. If you prefer I go straight to
> KUNIT_FAIL, I can make that change.

I see. It might have been useful when the patch removed the trailing '\n'.
But you are going to add it back. So there won't be any hidden change.
So I would prefer to go straight to KUNIT_FAIL().

> > > @@ -842,13 +836,15 @@ test_pointer(void)
> > >       fourcc_pointer();
> > >  }
> > >
> > > -static void __init selftest(void)
> > > +static void printf_test(struct kunit *test)
> > >  {
> > >       alloced_buffer = kmalloc(BUF_SIZE + 2*PAD_SIZE, GFP_KERNEL);
> > >       if (!alloced_buffer)
> > >               return;
> >
> > I would use here:
> >
> >         KUNIT_ASSERT_NOT_NULL(test, alloced_buffer);
> >
> > And move the same change for the other kmalloc() location from
> > the 2nd patch.
> 
> I didn't do that here because I was trying to keep this patch as small
> as possible, and I wrote that in the commit message.
> 
> As for using KUNIT_ASSERT_NOT_NULL here, that would have to change
> back to an error return in the 2nd patch because this code moves into
> `suite_init`, which is called with `struct kunit_suite` rather than
> `struct kunit_test`, and KUnit assertion macros do not work with the
> former (and for good reason, because failures in suite setup cannot be
> attributed to a particular test case).

I see. KUNIT_ASSERT_NOT_NULL() can't be used in the .suite_exit() callback.

> So I'd prefer to leave this as is.

I agree to leave this as is.

Best Regards,
Petr