linux-kernel - Re: [PATCH] scripts/setlocalversion: clear local varaible to make it work for sh

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Date:   Tue, 1 Oct 2019 15:20:27 +0200
From:   Geert Uytterhoeven <geert@...ux-m68k.org>
To:     Masahiro Yamada <yamada.masahiro@...ionext.com>
Cc:     Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] scripts/setlocalversion: clear local varaible to make it
 work for sh

Hi Yamada-san,

s/varaible/variable/ in subject.

On Tue, Oct 1, 2019 at 2:17 PM Masahiro Yamada
<yamada.masahiro@...ionext.com> wrote:
> Geert Uytterhoeven reports a strange side-effect of commit 858805b336be
> ("kbuild: add $(BASH) to run scripts with bash-extension"), which
> inserts the contents of a localversion file in the build directory twice.
>
> [Steps to Reproduce]
>   $ echo bar > localversion
>   $ mkdir build
>   $ cd build/
>   $ echo foo > localversion
>   $ make -s -f ../Makefile defconfig include/config/kernel.release
>   $ cat include/config/kernel.release
>   5.4.0-rc1foofoobar
>
> This comes down to the behavior change of 'local' variables.
>
> The 'man sh' on my Ubuntu machine, where sh is an alias to dash,
> explains as follows:
>   When a variable is made local, it inherits the initial value and
>   exported and readonly flags from the variable with the same name
>   in the surrounding scope, if there is one. Otherwise, the variable
>   is initially unset.
>
> [Test Code]
>
>   foo ()
>   {
>           local res
>           echo "res: $res"
>   }
>
>   res=1
>   foo
>
> [Result]
>
>   $ sh test.sh
>   res: 1
>   $ bash test.sh
>   res:
>
> So, scripts/setlocalversion correctly works only for bash in spite of
> its hashbang being #!/bin/sh. Nobody had noticed it before because
> CONFIG_SHELL was previously set to sh only when bash is missing, which
> is very unlikely to happen.
>
> The benefit of commit 858805b336be is to make people write portable and
> correct code. I gave it the Fixes tag since it uncovered the issue for
> most of people.
>
> Clear the variable 'res' in collect_files() to make it work for sh
> (and it also works on distributions where sh is an alias to bash).
>
> Fixes: commit 858805b336be ("kbuild: add $(BASH) to run scripts with bash-extension")
> Reported-by: Geert Uytterhoeven <geert@...ux-m68k.org>

Can you please use

    Reported-by: Geert Uytterhoeven <geert+renesas@...der.be>

instead?

> Signed-off-by: Masahiro Yamada <yamada.masahiro@...ionext.com>

Thanks, that fixes the issue for me!

Tested-by: Geert Uytterhoeven <geert+renesas@...der.be>

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds