linux-kernel - Re: [PATCH v1] kunit: fix failure to build without printk

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Message-ID: <CAFd5g47rSBJS8QVH6d5HqoJW5PJXdNnkoP6WcvQCFUqHUEmDzw@mail.gmail.com>
Date:   Tue, 27 Aug 2019 14:09:55 -0700
From:   Brendan Higgins <brendanhiggins@...gle.com>
To:     shuah <shuah@...nel.org>
Cc:     kunit-dev@...glegroups.com,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        "open list:KERNEL SELFTEST FRAMEWORK" 
        <linux-kselftest@...r.kernel.org>,
        Frank Rowand <frowand.list@...il.com>,
        Stephen Boyd <sboyd@...nel.org>,
        Randy Dunlap <rdunlap@...radead.org>,
        Stephen Rothwell <sfr@...b.auug.org.au>
Subject: Re: [PATCH v1] kunit: fix failure to build without printk

On Tue, Aug 27, 2019 at 2:03 PM Brendan Higgins
<brendanhiggins@...gle.com> wrote:
>
> On Tue, Aug 27, 2019 at 1:21 PM shuah <shuah@...nel.org> wrote:
> >
> > On 8/27/19 11:49 AM, Brendan Higgins wrote:
> > > Previously KUnit assumed that printk would always be present, which is
> > > not a valid assumption to make. Fix that by ifdefing out functions which
> > > directly depend on printk core functions similar to what dev_printk
> > > does.
> > >
> > > Reported-by: Randy Dunlap <rdunlap@...radead.org>
> > > Link: https://lore.kernel.org/linux-kselftest/0352fae9-564f-4a97-715a-fabe016259df@kernel.org/T/#t
> > > Cc: Stephen Rothwell <sfr@...b.auug.org.au>
> > > Signed-off-by: Brendan Higgins <brendanhiggins@...gle.com>
> > > ---
> > >   include/kunit/test.h |  7 +++++++
> > >   kunit/test.c         | 41 ++++++++++++++++++++++++-----------------
> > >   2 files changed, 31 insertions(+), 17 deletions(-)
> > >
> > > diff --git a/include/kunit/test.h b/include/kunit/test.h
> > > index 8b7eb03d4971..339af5f95c4a 100644
> > > --- a/include/kunit/test.h
> > > +++ b/include/kunit/test.h
> > > @@ -339,9 +339,16 @@ static inline void *kunit_kzalloc(struct kunit *test, size_t size, gfp_t gfp)
> [...]
> > Okay after reviewing this, I am not sure why you need to do all
> > this.
> >
> > Why can't you just change the root function that throws the warn:
> >
> >   static int kunit_vprintk_emit(int level, const char *fmt, va_list args)
> > {
> >          return vprintk_emit(0, level, NULL, 0, fmt, args);
> > }
> >
> > You aren'r really doing anything extra here, other than calling
> > vprintk_emit()
>
> Yeah, I did that a while ago. I think it was a combination of trying
> to avoid an extra layer of adding and then removing the log level, and
> that's what dev_printk and friends did.
>
> But I think you are probably right. It's a lot of maintenance overhead
> to get rid of that. Probably best to just use what the printk people
> have.
>
> > Unless I am missing something, can't you solve this problem by including
> > printk.h and let it handle the !CONFIG_PRINTK case?
>
> Randy, I hope you don't mind, but I am going to ask you to re-ack my
> next revision since it basically addresses the problem in a totally
> different way.

Actually, scratch that. Checkpatch doesn't like me calling printk
without using a KERN_<LEVEL>.

Now that I am thinking back to when I wrote this. I think it also
might not like using a dynamic KERN_<LEVEL> either (printk("%s my
message", KERN_INFO)).

I am going to have to do some more investigation.