Re: [PATCH] arcnet: com90xx: Mark expected switch fall-throughs

[Kees Cook <keescook@chromium.org>]

On Mon, Jul 29, 2019 at 06:09:53AM -0500, Gustavo A. R. Silva wrote:
> Mark switch cases where we are expecting to fall through.
> 
> This patch fixes the following warnings (Building: powerpc allyesconfig):
> 
> drivers/net/arcnet/com90xx.c: In function 'com90xx_setup':
> include/linux/printk.h:304:2: warning: this statement may fall through [-Wimplicit-fallthrough=]
>   printk(KERN_ERR pr_fmt(fmt), ##__VA_ARGS__)
>   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> drivers/net/arcnet/com90xx.c:695:3: note: in expansion of macro 'pr_err'
>    pr_err("Too many arguments\n");
>    ^~~~~~
> drivers/net/arcnet/com90xx.c:696:2: note: here
>   case 3:  /* Mem address */
>   ^~~~
> drivers/net/arcnet/com90xx.c:697:9: warning: this statement may fall through [-Wimplicit-fallthrough=]
>    shmem = ints[3];
>    ~~~~~~^~~~~~~~~
> drivers/net/arcnet/com90xx.c:698:2: note: here
>   case 2:  /* IRQ */
>   ^~~~
> drivers/net/arcnet/com90xx.c:699:7: warning: this statement may fall through [-Wimplicit-fallthrough=]
>    irq = ints[2];
>    ~~~~^~~~~~~~~
> drivers/net/arcnet/com90xx.c:700:2: note: here
>   case 1:  /* IO address */
>   ^~~~
> 
> Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
> Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>

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

-Kees

> ---
>  drivers/net/arcnet/com90xx.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/net/arcnet/com90xx.c b/drivers/net/arcnet/com90xx.c
> index ca4a57c30bf8..bd75d06ad7df 100644
> --- a/drivers/net/arcnet/com90xx.c
> +++ b/drivers/net/arcnet/com90xx.c
> @@ -693,10 +693,13 @@ static int __init com90xx_setup(char *s)
>  	switch (ints[0]) {
>  	default:		/* ERROR */
>  		pr_err("Too many arguments\n");
> +		/* Fall through */
>  	case 3:		/* Mem address */
>  		shmem = ints[3];
> +		/* Fall through */
>  	case 2:		/* IRQ */
>  		irq = ints[2];
> +		/* Fall through */
>  	case 1:		/* IO address */
>  		io = ints[1];
>  	}
> -- 
> 2.22.0
> 

-- 
Kees Cook