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From: Masahiro Yamada <masahiroy@kernel.org>
Date: Sat, 23 Dec 2023 02:57:00 +0900
Message-ID: <CAK7LNAQfzxiMoiLXvksUWtPiRhXQ7zypUzQpYER_7B=00XBr=A@mail.gmail.com>
Subject: Re: [PATCH v7 3/3] check-module-params: Introduce check-module-params.sh
To: John Moon <quic_johmoo@quicinc.com>
Cc: Christoph Hellwig <hch@infradead.org>, Nathan Chancellor <nathan@kernel.org>, 
	Nick Desaulniers <ndesaulniers@google.com>, Nicolas Schier <nicolas@fjasle.eu>, 
	Jonathan Corbet <corbet@lwn.net>, linux-kbuild@vger.kernel.org, linux-kernel@vger.kernel.org, 
	linux-arm-kernel@lists.infradead.org, linux-arm-msm@vger.kernel.org, 
	kernel@quicinc.com, Greg Kroah-Hartman <gregkh@linuxfoundation.org>, 
	Rob Herring <robh@kernel.org>, "Carlos O'Donell" <carlos@redhat.com>, 
	Randy Dunlap <rdunlap@infradead.org>, Arnd Bergmann <arnd@arndb.de>, 
	Bjorn Andersson <andersson@kernel.org>, Todd Kjos <tkjos@google.com>, 
	Matthias Maennich <maennich@google.com>, Giuliano Procida <gprocida@google.com>, kernel-team@android.com, 
	libabigail@sourceware.org, Dodji Seketeli <dodji@redhat.com>, 
	Trilok Soni <quic_tsoni@quicinc.com>, 
	Satya Durga Srinivasu Prabhala <quic_satyap@quicinc.com>, Jordan Crouse <jorcrous@amazon.com>
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On Wed, Dec 13, 2023 at 1:58=E2=80=AFAM John Moon <quic_johmoo@quicinc.com>=
 wrote:
>
> On 12/11/2023 11:41 PM, Christoph Hellwig wrote:
> > On Mon, Dec 11, 2023 at 06:02:59PM -0800, John Moon wrote:
> >> One part of maintaining backwards compatibility with older
> >> userspace programs is avoiding changes to module parameters.
> >
> > Really?  I don't think module parameters are a UAPI in the traditional
> > sense.
>
> Agreed, they're not UAPI in the traditional sense. But, we're trying to
> establish tooling to help the community stabilize all interfaces that
> cross the kernel <-> userspace boundary and module params do fall into
> that bucket.
>
> > Now if you break a heavily used one you got to fix it, but
> > applying strict stability guarantees on module options which are not
> > availble to normal users or even normal programs doesn't make a whole
> > lot of sense.
> >
>
> True, but unfortunately we don't have any heuristic to determine if a
> param is "heavily used". However, in this rev, we added the ability to
> parse the permissions of a module param, so we could add a filter which
> does not flag change/removal of params with 0{0,4,6}000 permissions.
>
> It's also obviously fine if the community has no interest in the script.
> We just wanted to share it as we find it to be a useful supplement to
> our code reviews and thought maintainers may find it useful as well.
>
> Cheers,
> John


I am with Christoph.

This tool detects some changes and removals, but I think
the community intentionally changed them.

To merge this tool in the mainline,
I need more people who are interested in this.


--=20
Best Regards
Masahiro Yamada