linux-kernel - Re: [PATCH v2] USB: serial: io_edgeport: mark expected switch fall-throughs

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Message-ID: <20190502102608.GS26546@localhost>
Date:   Thu, 2 May 2019 12:26:08 +0200
From:   Johan Hovold <johan@...nel.org>
To:     "Gustavo A. R. Silva" <gustavo@...eddedor.com>
Cc:     Johan Hovold <johan@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
        Kees Cook <keescook@...omium.org>
Subject: Re: [PATCH v2] USB: serial: io_edgeport: mark expected switch
 fall-throughs

On Wed, May 01, 2019 at 04:33:29PM -0500, 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 warnings:
> 
> drivers/usb/serial/io_edgeport.c: In function ‘process_rcvd_data’:
> drivers/usb/serial/io_edgeport.c:1750:7: warning: this statement may fall through [-Wimplicit-fallthrough=]
>     if (bufferLength == 0) {
>        ^
> drivers/usb/serial/io_edgeport.c:1755:3: note: here
>    case EXPECT_HDR2:
>    ^~~~
> drivers/usb/serial/io_edgeport.c:1810:8: warning: this statement may fall through [-Wimplicit-fallthrough=]
>      if (bufferLength == 0) {
>         ^
> drivers/usb/serial/io_edgeport.c:1816:3: note: here
>    case EXPECT_DATA: /* Expect data */
>    ^~~~
> 
> 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>
> ---
> Changes in v2:
>  - Warning level 3 is now used: -Wimplicit-fallthrough=3
>    instead of warning level 2.
>  - All warnings in the switch statement are addressed now.
> 
> Notice that these are the last remaining fall-through warnings
> in the USB subsystem. :)

>  drivers/usb/serial/io_edgeport.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/usb/serial/io_edgeport.c b/drivers/usb/serial/io_edgeport.c
> index 4ca31c0e4174..7ad10328f4e2 100644
> --- a/drivers/usb/serial/io_edgeport.c
> +++ b/drivers/usb/serial/io_edgeport.c
> @@ -1751,7 +1751,7 @@ static void process_rcvd_data(struct edgeport_serial *edge_serial,
>  				edge_serial->rxState = EXPECT_HDR2;
>  				break;
>  			}
> -			/* otherwise, drop on through */
> +			/* Fall through - otherwise, drop on through */
>  		case EXPECT_HDR2:
>  			edge_serial->rxHeader2 = *buffer;
>  			++buffer;
> @@ -1813,6 +1813,7 @@ static void process_rcvd_data(struct edgeport_serial *edge_serial,
>  				}
>  				/* Else, drop through */
>  			}
> +			/* Fall through */
>  		case EXPECT_DATA: /* Expect data */

Looks like you forgot to take the original review feedback you got into
account:

	https://lkml.kernel.org/r/87k1zf4k24.fsf@miraculix.mork.no

Johan