linux-kernel - Re: [PATCH] platform/x86: thinkpad_acpi: Mark expected switch fall-throughs

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Date:   Wed, 24 Apr 2019 12:05:01 -0700
From:   Kees Cook <keescook@...omium.org>
To:     "Gustavo A. R. Silva" <gustavo@...eddedor.com>
Cc:     Henrique de Moraes Holschuh <ibm-acpi@....eng.br>,
        Darren Hart <dvhart@...radead.org>,
        Andy Shevchenko <andy@...radead.org>,
        ibm-acpi-devel@...ts.sourceforge.net,
        Platform Driver <platform-driver-x86@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] platform/x86: thinkpad_acpi: Mark expected switch fall-throughs

On Wed, Apr 24, 2019 at 11:15 AM Gustavo A. R. Silva
<gustavo@...eddedor.com> wrote:
>
> In preparation to enabling -Wimplicit-fallthrough, mark switch
> cases where we are expecting to fall through.
>
> This patch fixes the following warnings:
>
> drivers/platform/x86/thinkpad_acpi.c: In function ‘thermal_get_sensor’:
> drivers/platform/x86/thinkpad_acpi.c:6316:6: warning: this statement may fall through [-Wimplicit-fallthrough=]
>    if (idx >= 8 && idx <= 15) {
>       ^
> drivers/platform/x86/thinkpad_acpi.c:6322:2: note: here
>   case TPACPI_THERMAL_TPEC_8:
>   ^~~~
> drivers/platform/x86/thinkpad_acpi.c: In function ‘hotkey_notify’:
> drivers/platform/x86/thinkpad_acpi.c:4208:7: warning: this statement may fall through [-Wimplicit-fallthrough=]
>     if (tp_features.hotkey_wlsw &&
>        ^
> drivers/platform/x86/thinkpad_acpi.c:4216:3: note: here
>    default:
>    ^~~~~~~
>
> Warning level 3 was used: -Wimplicit-fallthrough=3
>
> Notice that, in this particular case, the code comments are modified
> in accordance with what GCC is expecting to find.
>
> This patch is part of the ongoing efforts to enable
> -Wimplicit-fallthrough.
>
> Signed-off-by: Gustavo A. R. Silva <gustavo@...eddedor.com>

Reviewed-by: Kees Cook <keescook@...omium.org>

-Kees

> ---
>  drivers/platform/x86/thinkpad_acpi.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/platform/x86/thinkpad_acpi.c b/drivers/platform/x86/thinkpad_acpi.c
> index 57d9ae9d8e56..826e9a276818 100644
> --- a/drivers/platform/x86/thinkpad_acpi.c
> +++ b/drivers/platform/x86/thinkpad_acpi.c
> @@ -4212,7 +4212,7 @@ static void hotkey_notify(struct ibm_struct *ibm, u32 event)
>                                 known_ev = true;
>                                 break;
>                         }
> -                       /* fallthrough to default */
> +                       /* fallthrough - to default */
>                 default:
>                         known_ev = false;
>                 }
> @@ -6317,8 +6317,8 @@ static int thermal_get_sensor(int idx, s32 *value)
>                         t = TP_EC_THERMAL_TMP8;
>                         idx -= 8;
>                 }
> -               /* fallthrough */
>  #endif
> +               /* fallthrough */
>         case TPACPI_THERMAL_TPEC_8:
>                 if (idx <= 7) {
>                         if (!acpi_ec_read(t + idx, &tmp))
> --
> 2.21.0
>


-- 
Kees Cook