linux-kernel - Re: [PATCH] watchdog: alim7101: Mark expected switch fall-through

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Date:   Wed, 20 Mar 2019 17:12:02 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     "Gustavo A. R. Silva" <gustavo@...eddedor.com>,
        Wim Van Sebroeck <wim@...ux-watchdog.org>
Cc:     linux-watchdog@...r.kernel.org, linux-kernel@...r.kernel.org,
        Kees Cook <keescook@...omium.org>
Subject: Re: [PATCH] watchdog: alim7101: Mark expected switch fall-through

On 3/20/19 11:16 AM, Gustavo A. R. Silva wrote:
> In preparation to enabling -Wimplicit-fallthrough, mark switch
> cases where we are expecting to fall through.
> 
> This patch fixes the following warning:
> 
> drivers/watchdog/alim7101_wdt.c: In function ‘fop_ioctl’:
> drivers/watchdog/alim7101_wdt.c:279:3: warning: this statement may fall through [-Wimplicit-fallthrough=]
>     wdt_keepalive();
>     ^~~~~~~~~~~~~~~
> drivers/watchdog/alim7101_wdt.c:282:2: note: here
>    case WDIOC_GETTIMEOUT:
>    ^~~~
> 
> Notice that, in this particular case, the /* Fall through */
> comment is placed at the very bottom of the case statement,
> which is what GCC is expecting to find.
> 
> Warning level 3 was used: -Wimplicit-fallthrough=3
> 
> This patch is part of the ongoing efforts to enabling
> -Wimplicit-fallthrough.
> 
> Signed-off-by: Gustavo A. R. Silva <gustavo@...eddedor.com>

Reviewed-by: Guenter Roeck <linux@...ck-us.net>

> ---
>   drivers/watchdog/alim7101_wdt.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/watchdog/alim7101_wdt.c b/drivers/watchdog/alim7101_wdt.c
> index 12f7ea62dddd..f5ada07e9202 100644
> --- a/drivers/watchdog/alim7101_wdt.c
> +++ b/drivers/watchdog/alim7101_wdt.c
> @@ -277,8 +277,8 @@ static long fop_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
>   			return -EINVAL;
>   		timeout = new_timeout;
>   		wdt_keepalive();
> -		/* Fall through */
>   	}
> +		/* Fall through */
>   	case WDIOC_GETTIMEOUT:
>   		return put_user(timeout, p);
>   	default:
>