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References: <20230327174140.8169-1-quic_johmoo@quicinc.com> <20230327174140.8169-2-quic_johmoo@quicinc.com>
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From:   Masahiro Yamada <masahiroy@kernel.org>
Date:   Sat, 8 Apr 2023 04:27:57 +0900
Message-ID: <CAK7LNATFzdb37ZpOkYOP0rGBBjMhad6p76CXJg7kZsNkhpoBXg@mail.gmail.com>
Subject: Re: [PATCH v4 1/2] check-uapi: Introduce check-uapi.sh
To:     John Moon <quic_johmoo@quicinc.com>
Cc:     Nathan Chancellor <nathan@kernel.org>,
        Nick Desaulniers <ndesaulniers@google.com>,
        Nicolas Schier <nicolas@fjasle.eu>,
        linux-kbuild@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org,
        linux-arm-msm@vger.kernel.org,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        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,
        Jordan Crouse <jorcrous@amazon.com>,
        Trilok Soni <quic_tsoni@quicinc.com>,
        Satya Durga Srinivasu Prabhala <quic_satyap@quicinc.com>,
        Elliot Berman <quic_eberman@quicinc.com>,
        Guru Das Srinagesh <quic_gurus@quicinc.com>
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On Tue, Mar 28, 2023 at 2:42=E2=80=AFAM John Moon <quic_johmoo@quicinc.com>=
 wrote:
>
> While the kernel community has been good at maintaining backwards
> compatibility with kernel UAPIs, it would be helpful to have a tool
> to check if a commit introduces changes that break backwards
> compatibility.
>
> To that end, introduce check-uapi.sh: a simple shell script that
> checks for changes to UAPI headers using libabigail.
>
> libabigail is "a framework which aims at helping developers and
> software distributors to spot some ABI-related issues like interface
> incompatibility in ELF shared libraries by performing a static
> analysis of the ELF binaries at hand."
>
> The script uses one of libabigail's tools, "abidiff", to compile the
> changed header before and after the commit to detect any changes.
>
> abidiff "compares the ABI of two shared libraries in ELF format. It
> emits a meaningful report describing the differences between the two
> ABIs."
>
> The script also includes the ability to check the compatibility of
> all UAPI headers across commits. This allows developers to inspect
> the stability of the UAPIs over time.
>
> Signed-off-by: John Moon <quic_johmoo@quicinc.com>
> ---
>     - Refactored to exclusively check headers installed by make
>       headers_install. This simplified the code dramatically and removed
>       the need to perform complex git diffs.
>     - Removed the "-m" flag. Since we're checking all installed headers
>       every time, a flag to check only modified files didn't make sense.
>     - Added info message when usr/include/Makefile is not present that
>       it's likely because that file was only introduced in v5.3.
>     - Changed default behavior of log file. Now, the script will not
>       create a log file unless you pass "-l <file>".
>     - Simplified exit handler.
>     - Added -j $MAX_THREADS to make headers_install to improve speed.
>     - Cleaned up variable references.
>
>  scripts/check-uapi.sh | 488 ++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 488 insertions(+)
>  create mode 100755 scripts/check-uapi.sh
>

> +
> +# Install headers for both git refs
> +install_headers() {
> +       local -r base_ref=3D"$1"
> +       local -r past_ref=3D"$2"
> +
> +       DEVIATED_FROM_CURRENT_TREE=3D"false"
> +       for ref in "$base_ref" "$past_ref"; do
> +               if [ -n "$ref" ]; then
> +                       if [ "$DEVIATED_FROM_CURRENT_TREE" =3D "false" ];=
 then
> +                               save_tree_state
> +                               DEVIATED_FROM_CURRENT_TREE=3D"true"
> +                       fi
> +                       # This script ($0) is already loaded into memory =
at this point,
> +                       # so this operation is safe
> +                       git checkout --quiet "$(git rev-parse "$ref")"
> +               fi
> +
> +               printf "Installing sanitized UAPI headers from %s... " "$=
{ref:-dirty tree}"
> +               make -j "$MAX_THREADS" ARCH=3D"$ARCH" INSTALL_HDR_PATH=3D=
"${TMP_DIR}/${ref}/usr" headers_install > /dev/null 2>&1


You suppressed stderr.

If 'make headers_install' fails, users see a sudden death
with no clue.


--=20
Best Regards
Masahiro Yamada