linux-kernel - Re: [PATCH] iio: mma8452: mark expected switch fall-through

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Date:   Wed, 20 Feb 2019 12:17:26 +0000
From:   Jonathan Cameron <jic23@...nel.org>
To:     "Gustavo A. R. Silva" <gustavo@...eddedor.com>
Cc:     Hartmut Knaack <knaack.h@....de>,
        Lars-Peter Clausen <lars@...afoo.de>,
        Peter Meerwald-Stadler <pmeerw@...erw.net>,
        linux-iio@...r.kernel.org, linux-kernel@...r.kernel.org,
        Kees Cook <keescook@...omium.org>
Subject: Re: [PATCH] iio: mma8452: mark expected switch fall-through

On Mon, 11 Feb 2019 16:23:18 -0600
"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 warning:
> 
> drivers/iio/accel/mma8452.c: In function ‘mma8452_probe’:
> drivers/iio/accel/mma8452.c:1581:6: warning: this statement may fall through [-Wimplicit-fallthrough=]
>    if (ret == data->chip_info->chip_id)
>       ^
> drivers/iio/accel/mma8452.c:1584:2: note: here
>   default:
>   ^~~~~~~
> 
> Warning level 3 was used: -Wimplicit-fallthrough=3
> 
> Notice that, in this particular case, the code comment is 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>
I know Peter probably won't like this, as it doesn't
read a as well, with the else dropped, but I'm going to take
it as we have had a lot of bugs caught by this code and this
is generating a false positive.

Applied to the togreg branch of iio.git and pushed out as testing
for the autobuilders to play with it.

Thanks,

Jonathan

> ---
>  drivers/iio/accel/mma8452.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/iio/accel/mma8452.c b/drivers/iio/accel/mma8452.c
> index 302781126bc6..00e100fc845a 100644
> --- a/drivers/iio/accel/mma8452.c
> +++ b/drivers/iio/accel/mma8452.c
> @@ -1580,7 +1580,7 @@ static int mma8452_probe(struct i2c_client *client,
>  	case FXLS8471_DEVICE_ID:
>  		if (ret == data->chip_info->chip_id)
>  			break;
> -		/* else: fall through */
> +		/* fall through */
>  	default:
>  		ret = -ENODEV;
>  		goto disable_regulators;