linux-kernel - Re: [PATCH] kdb: Make the internal env 'KDBFLAGS' undefinable

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Date:   Wed, 13 May 2020 16:41:07 -0700
From:   Doug Anderson <dianders@...omium.org>
To:     Wei Li <liwei391@...wei.com>
Cc:     Jason Wessel <jason.wessel@...driver.com>,
        Daniel Thompson <daniel.thompson@...aro.org>,
        Masahiro Yamada <yamada.masahiro@...ionext.com>,
        kgdb-bugreport@...ts.sourceforge.net,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] kdb: Make the internal env 'KDBFLAGS' undefinable

Hi,

On Sun, May 10, 2020 at 7:18 PM Wei Li <liwei391@...wei.com> wrote:
>
> 'KDBFLAGS' is an internal variable of kdb, it is combined by 'KDBDEBUG'
> and state flags. But the user can define an environment variable named
> 'KDBFLAGS' too, so let's make it undefinable to avoid confusion.
>
> Signed-off-by: Wei Li <liwei391@...wei.com>
> ---
>  kernel/debug/kdb/kdb_main.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/kernel/debug/kdb/kdb_main.c b/kernel/debug/kdb/kdb_main.c
> index 4fc43fb17127..d3d060136821 100644
> --- a/kernel/debug/kdb/kdb_main.c
> +++ b/kernel/debug/kdb/kdb_main.c
> @@ -423,7 +423,8 @@ int kdb_set(int argc, const char **argv)
>                         | (debugflags << KDB_DEBUG_FLAG_SHIFT);
>
>                 return 0;
> -       }
> +       } else if (strcmp(argv[1], "KDBFLAGS") == 0)
> +               return KDB_NOPERM;

One slight nit is that my personal preference is that if one half of
an "if/else" needs braces then both halves should have braces.  I
don't know what Daniel and Jason's policies are, though.  In any case,
not that I've ever used the KDBDEBUG functionality, but your change
seems sane.  Without it if I set "KDBDEBUG" and "KDBFLAGS" and then
type "env" I see the flags listed twice, but one is real and one is
fake.

Reviewed-by: Douglas Anderson <dianders@...omium.org>

-Doug