linux-kernel - Re: [PATCH] i2c: s3c2410: Mark expected switch fall-through

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Date:   Mon, 29 Jul 2019 09:34:55 -0700
From:   Kees Cook <keescook@...omium.org>
To:     "Gustavo A. R. Silva" <gustavo@...eddedor.com>
Cc:     Kukjin Kim <kgene@...nel.org>,
        Krzysztof Kozlowski <krzk@...nel.org>,
        linux-arm-kernel@...ts.infradead.org,
        linux-samsung-soc@...r.kernel.org, linux-i2c@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Stephen Rothwell <sfr@...b.auug.org.au>
Subject: Re: [PATCH] i2c: s3c2410: Mark expected switch fall-through

On Sun, Jul 28, 2019 at 06:51:38PM -0500, Gustavo A. R. Silva wrote:
> Mark switch cases where we are expecting to fall through.
> 
> This patch fixes the following warning:
> 
> drivers/i2c/busses/i2c-s3c2410.c: In function 'i2c_s3c_irq_nextbyte':
> drivers/i2c/busses/i2c-s3c2410.c:431:6: warning: this statement may fall through [-Wimplicit-fallthrough=]
>    if (i2c->state == STATE_READ)
>       ^
> drivers/i2c/busses/i2c-s3c2410.c:439:2: note: here
>   case STATE_WRITE:
>   ^~~~
> 
> Notice that, in this particular case, the code comment is
> modified in accordance with what GCC is expecting to find.
> 
> Reported-by: Stephen Rothwell <sfr@...b.auug.org.au>
> Signed-off-by: Gustavo A. R. Silva <gustavo@...eddedor.com>

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

-Kees

> ---
>  drivers/i2c/busses/i2c-s3c2410.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/i2c/busses/i2c-s3c2410.c b/drivers/i2c/busses/i2c-s3c2410.c
> index d97fb857b0ea..c98ef4c4a0c9 100644
> --- a/drivers/i2c/busses/i2c-s3c2410.c
> +++ b/drivers/i2c/busses/i2c-s3c2410.c
> @@ -435,6 +435,7 @@ static int i2c_s3c_irq_nextbyte(struct s3c24xx_i2c *i2c, unsigned long iicstat)
>  		 * fall through to the write state, as we will need to
>  		 * send a byte as well
>  		 */
> +		/* Fall through */
>  
>  	case STATE_WRITE:
>  		/*
> -- 
> 2.22.0
> 

-- 
Kees Cook