linux-kernel - Re: [PATCH] sound: dmasound_atari: Mark expected switch fall-through

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Message-ID: <CAMuHMdWAboq1YxVVJUop0woJTcantfpftVoR8T5qm3KsAMyCPg@mail.gmail.com>
Date:   Mon, 29 Jul 2019 17:35:16 +0200
From:   Geert Uytterhoeven <geert@...ux-m68k.org>
To:     "Gustavo A. R. Silva" <gustavo@...eddedor.com>
Cc:     Jaroslav Kysela <perex@...ex.cz>, Takashi Iwai <tiwai@...e.com>,
        ALSA Development Mailing List <alsa-devel@...a-project.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Kees Cook <keescook@...omium.org>,
        linux-m68k <linux-m68k@...ts.linux-m68k.org>
Subject: Re: [PATCH] sound: dmasound_atari: Mark expected switch fall-through

Hi Gustavo,

Thanks for your patch!

On Mon, Jul 29, 2019 at 4:33 PM Gustavo A. R. Silva
<gustavo@...eddedor.com> wrote:
> Mark switch cases where we are expecting to fall through.
>
> This patch fixes the following warning:
>
> sound/oss/dmasound/dmasound_atari.c: warning: this statement may fall
> through [-Wimplicit-fallthrough=]:  => 1449:24
>
> Notice that, in this particular case, the code comment is
> modified in accordance with what GCC is expecting to find.

Have you compile-tested this?

This doesn't work with gcc version 8.2.0 (Ubuntu 8.2.0-1ubuntu2~18.04).
Turns out the warning only goes away when converting the indentation
of the switch() statement to match kernel style... Silly gcc...

> Reported-by: Geert Uytterhoeven <geert@...ux-m68k.org>
> Signed-off-by: Gustavo A. R. Silva <gustavo@...eddedor.com>
> ---
>  sound/oss/dmasound/dmasound_atari.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/sound/oss/dmasound/dmasound_atari.c b/sound/oss/dmasound/dmasound_atari.c
> index 83653683fd68..b5845e904ba1 100644
> --- a/sound/oss/dmasound/dmasound_atari.c
> +++ b/sound/oss/dmasound/dmasound_atari.c
> @@ -1449,7 +1449,7 @@ static int FalconMixerIoctl(u_int cmd, u_long arg)
>                 tt_dmasnd.input_gain =
>                         RECLEVEL_VOXWARE_TO_GAIN(data & 0xff) << 4 |
>                         RECLEVEL_VOXWARE_TO_GAIN(data >> 8 & 0xff);
> -               /* fall thru, return set value */
> +               /* fall through - return set value */
>             case SOUND_MIXER_READ_MIC:
>                 return IOCTL_OUT(arg,
>                         RECLEVEL_GAIN_TO_VOXWARE(tt_dmasnd.input_gain >> 4 & 0xf) |

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