linux-kernel - Re: [PATCH v2] scripts/check-local-export: avoid 'wait $!' for process substitution

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Message-ID: <CAKwvOdk5ZrcSmQSPrFzreZ-z_Hpi4Lc-D-Y4NDuHPiUWpXdwzA@mail.gmail.com>
Date:   Tue, 7 Jun 2022 10:24:20 -0700
From:   Nick Desaulniers <ndesaulniers@...gle.com>
To:     Masahiro Yamada <masahiroy@...nel.org>
Cc:     linux-kbuild@...r.kernel.org,
        Tetsuo Handa <penguin-kernel@...ove.sakura.ne.jp>,
        Michael Ellerman <mpe@...erman.id.au>,
        Wang Yugui <wangyugui@...-tech.com>,
        Jon Hunter <jonathanh@...dia.com>,
        Jonathan Corbet <corbet@....net>,
        Nathan Chancellor <nathan@...nel.org>,
        Tom Rix <trix@...hat.com>, linux-doc@...r.kernel.org,
        linux-kernel@...r.kernel.org, llvm@...ts.linux.dev
Subject: Re: [PATCH v2] scripts/check-local-export: avoid 'wait $!' for
 process substitution

On Tue, Jun 7, 2022 at 9:41 AM Masahiro Yamada <masahiroy@...nel.org> wrote:
>
> Bash>=4.4 supports 'wait $!' to check the exit status of a process
> substitution, but some people using older bash versions reported an
> error like this:
>
> Reported-by: Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>
> Reported-by: Michael Ellerman <mpe@...erman.id.au>
> Reported-by: Wang Yugui <wangyugui@...-tech.com>
> Tested-by: Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>
> Tested-by: Jon Hunter <jonathanh@...dia.com>
> Signed-off-by: Masahiro Yamada <masahiroy@...nel.org>

Acked-by: Nick Desaulniers <ndesaulniers@...gle.com>

Some comments below.

> diff --git a/Documentation/process/changes.rst b/Documentation/process/changes.rst
> index 34415ae1af1b..19c286c23786 100644
> --- a/Documentation/process/changes.rst
> +++ b/Documentation/process/changes.rst
> @@ -32,6 +32,7 @@ you probably needn't concern yourself with pcmciautils.
>  GNU C                  5.1              gcc --version
>  Clang/LLVM (optional)  11.0.0           clang --version
>  GNU make               3.81             make --version
> +bash                   4.2              bash --version

/usr/bin/env bash
and definitely /bin/bash
both show up a lot in kernel sources. At this point, I think bash is a
requirement at this point, so it's good to document it finally.

> +# If there is no symbol in the object, ${NM} (both GNU nm and llvm-nm) shows
> +# 'no symbols' diagnostic (but exits with 0). It is harmless and hidden by
> +# '2>/dev/null'. However, it suppresses real error messages as well. Add a
> +# hand-crafted error message here.
> +#
> +# Use --quiet instead of 2>/dev/null when we upgrade the minimum version of
> +# binutils to 2.37, llvm to 13.0.0.

Might be nice to include `TODO:` in the comment block. Vim will
highlight these in comments.

-- 
Thanks,
~Nick Desaulniers