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Date:   Fri, 3 Apr 2020 12:58:21 +0100 (BST)
From:   Alan Maguire <alan.maguire@oracle.com>
To:     Greg KH <gregkh@linuxfoundation.org>
cc:     Alan Maguire <alan.maguire@oracle.com>, shuah <shuah@kernel.org>,
        brendanhiggins@google.com, frowand.list@gmail.com,
        linux-kselftest@vger.kernel.org, corbet@lwn.net,
        linux-kernel@vger.kernel.org, kunit-dev@googlegroups.com,
        linux-doc@vger.kernel.org
Subject: Re: [PATCH v8 kunit-next 1/4] kunit: add debugfs
 /sys/kernel/debug/kunit/<suite>/results display
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On Thu, 2 Apr 2020, Greg KH wrote:

> On Thu, Apr 02, 2020 at 04:27:35PM +0100, Alan Maguire wrote:
> > On Wed, 1 Apr 2020, shuah wrote:
> > 
> > > Hi Alan,
> > > 
> > > On 3/26/20 8:25 AM, Alan Maguire wrote:
> > > > add debugfs support for displaying kunit test suite results; this is
> > > > especially useful for module-loaded tests to allow disentangling of
> > > > test result display from other dmesg events.  debugfs support is
> > > > provided if CONFIG_KUNIT_DEBUGFS=y.
> > > > 
> > > > As well as printk()ing messages, we append them to a per-test log.
> > > > 
> > > > Signed-off-by: Alan Maguire <alan.maguire@oracle.com>
> > > > Reviewed-by: Brendan Higgins <brendanhiggins@google.com>
> > > > Reviewed-by: Frank Rowand <frank.rowand@sony.com>
> > > > ---
> > > >   include/kunit/test.h   |  54 +++++++++++++++---
> > > >   lib/kunit/Kconfig      |   8 +++
> > > 
> > > Missing defaults for config options?
> > > 
> > > >   lib/kunit/Makefile     |   4 ++
> > > >   lib/kunit/debugfs.c    | 116 ++++++++++++++++++++++++++++++++++++++
> > > >   lib/kunit/debugfs.h    |  30 ++++++++++
> > > >   lib/kunit/kunit-test.c |   4 +-
> > > >   lib/kunit/test.c       | 147
> > > >   ++++++++++++++++++++++++++++++++++++++-----------
> > > >   7 files changed, 322 insertions(+), 41 deletions(-)
> > > >   create mode 100644 lib/kunit/debugfs.c
> > > >   create mode 100644 lib/kunit/debugfs.h
> > > > 
> > > 
> > > snip
> > > 
> > > > diff --git a/lib/kunit/Kconfig b/lib/kunit/Kconfig
> > > > index 065aa16..95d12e3 100644
> > > > --- a/lib/kunit/Kconfig
> > > > +++ b/lib/kunit/Kconfig
> > > > @@ -14,6 +14,14 @@ menuconfig KUNIT
> > > >   
> > > >   if KUNIT
> > > >   
> > > > +config KUNIT_DEBUGFS
> > > > +	bool "KUnit - Enable /sys/kernel/debug/kunit debugfs representation"
> > > > +	help
> > > > +	  Enable debugfs representation for kunit.  Currently this consists
> > > > +	  of /sys/kernel/debug/kunit/<test_suite>/results files for each
> > > > +	  test suite, which allow users to see results of the last test suite
> > > > +	  run that occurred.
> > > > +
> > > 
> > > Any reason why there is default for this option?
> > > 
> > > Same for all other options. I am sending pull request for now without
> > > defaults. Would like to see this fixed for rc2.
> > >
> > 
> > Sure, I'll send a patch shortly. Just wanted to get opinions
> > on what those defaults should be; my working assumption is
> > 
> > - CONFIG_KUNIT should be default n; 
> 
> No default means 'n', so there's no need to say that at all.
> 

Great!

> > - CONFIG_KUNIT_DEBUGFS should be default y (enabled by default
> >   if CONFIG_KUNIT is set);
> 
> Why?  If it's is 'y', then don't even make it an option at all, just
> always have it :)
> 
> 'y' is almost always reserved for "your machine will not function
> properly without this enabled".
>

Okay, so in this case not having a default makes sense I think
(we added the option as saying 'n' avoids allocating per-test
loggging memory which might cause problems on low-memory systems).

> > - CONFIG_KUNIT_TEST, CONFIG_KUNIT_EXAMPLE_TEST should be default n
> 
> So no need to specify anything, 'n' is the default.
>

Excellent! So based on the above seems like we don't need
to add any defaults here I think.  Shuah/Brendan, let me know
if I'm missing anything here. Thanks!

Alan

> thanks,
> 
> greg k-h
>