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From:   Arnd Bergmann <arnd@arndb.de>
Date:   Fri, 17 Sep 2021 09:38:09 +0200
Message-ID: <CAK8P3a257cAgtPhT1Li2GnZ-UZW3LVZa3fWX1YUnWGEENvpqJA@mail.gmail.com>
Subject: Re: [PATCH v1 0/6] kunit: build kunit tests without structleak plugin
To:     Brendan Higgins <brendanhiggins@google.com>
Cc:     Shuah Khan <shuah@kernel.org>, David Gow <davidgow@google.com>,
        Arnd Bergmann <arnd@arndb.de>,
        Kees Cook <keescook@chromium.org>,
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        YehezkelShB@gmail.com, Masahiro Yamada <masahiroy@kernel.org>,
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On Fri, Sep 17, 2021 at 8:10 AM Brendan Higgins
<brendanhiggins@google.com> wrote:
>
> The structleak plugin causes the stack frame size to grow immensely when
> used with KUnit; this is caused because KUnit allocates lots of
> moderately sized structs on the stack as part of its assertion macro
> implementation. For most tests with small to moderately sized tests
> cases there are never enough KUnit assertions to be an issue at all;
> even when a single test cases has many KUnit assertions, the compiler
> should never put all these struct allocations on the stack at the same
> time since the scope of the structs is so limited; however, the
> structleak plugin does not seem to respect the compiler doing the right
> thing and will still warn of excessive stack size in some cases.
>
> These patches are not a permanent solution since new tests can be added
> with huge test cases, but this serves as a stop gap to stop structleak
> from being used on KUnit tests which will currently result in excessive
> stack size.
>
> Of the following patches, I think the thunderbolt patch may be
> unnecessary since Linus already fixed that test. Additionally, I was not
> able to reproduce the error on the sdhci-of-aspeed test. Nevertheless, I
> included these tests cases for completeness. Please see my discussion
> with Arnd for more context[1].
>
> NOTE: Arnd did the legwork for most of these patches, but did not
> actually share code for some of them, so I left his Signed-off-by off of
> those patches as I don't want to misrepresent him. Arnd, please sign off
> on those patches at your soonest convenience.

Thanks a lot for picking up this work where I dropped the ball.

Patches 1-5 look good to me, and I replied on one remaining issue I see
with patch 6. I think you did more work on these that I did, by doing
a nice write-up and splitting them into separate patches with useful
changelogs, you should keep authorship, and just change my
S-o-b to Suggested-by.

If you prefer to keep me as the author, then the correct way would
be to commit them with --author= to ensure that the author and
first s-o-b match.

        Arnd