linux-kernel - Re: [PATCH] gdbstub: mark expected switch fall-throughs

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Date:   Tue, 26 Feb 2019 14:47:28 -0600
From:   Jason Wessel <jason.wessel@...driver.com>
To:     "Gustavo A. R. Silva" <gustavo@...eddedor.com>,
        Daniel Thompson <daniel.thompson@...aro.org>
CC:     <kgdb-bugreport@...ts.sourceforge.net>,
        <linux-kernel@...r.kernel.org>, Kees Cook <keescook@...omium.org>
Subject: Re: [PATCH] gdbstub: mark expected switch fall-throughs

We'll have to fix them at some point.

Acked-by: Jason Wessel <jason.wessel@...driver.com>


Cheers,
Jason.

On 2/26/19 1:16 PM, 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:
> 
> kernel/debug/gdbstub.c: In function ‘gdb_serial_stub’:
> kernel/debug/gdbstub.c:1031:7: warning: this statement may fall through [-Wimplicit-fallthrough=]
>      if (remcom_in_buffer[1] == '\0') {
>         ^
> kernel/debug/gdbstub.c:1036:3: note: here
>     case 'C': /* Exception passing */
>     ^~~~
> kernel/debug/gdbstub.c:1040:7: warning: this statement may fall through [-Wimplicit-fallthrough=]
>      if (tmp == 0)
>         ^
> kernel/debug/gdbstub.c:1043:3: note: here
>     case 'c': /* Continue packet */
>     ^~~~
> kernel/debug/gdbstub.c:1050:4: warning: this statement may fall through [-Wimplicit-fallthrough=]
>      dbg_activate_sw_breakpoints();
>      ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> kernel/debug/gdbstub.c:1052:3: 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>
> ---
>   kernel/debug/gdbstub.c | 5 +++--
>   1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/kernel/debug/gdbstub.c b/kernel/debug/gdbstub.c
> index 7510dc687c0d..9f267b8905b4 100644
> --- a/kernel/debug/gdbstub.c
> +++ b/kernel/debug/gdbstub.c
> @@ -1033,13 +1033,14 @@ int gdb_serial_stub(struct kgdb_state *ks)
>   				return DBG_PASS_EVENT;
>   			}
>   #endif
> +			/* Fall through */
>   		case 'C': /* Exception passing */
>   			tmp = gdb_cmd_exception_pass(ks);
>   			if (tmp > 0)
>   				goto default_handle;
>   			if (tmp == 0)
>   				break;
> -			/* Fall through on tmp < 0 */
> +			/* Fall through - on tmp < 0 */
>   		case 'c': /* Continue packet */
>   		case 's': /* Single step packet */
>   			if (kgdb_contthread && kgdb_contthread != current) {
> @@ -1048,7 +1049,7 @@ int gdb_serial_stub(struct kgdb_state *ks)
>   				break;
>   			}
>   			dbg_activate_sw_breakpoints();
> -			/* Fall through to default processing */
> +			/* Fall through - to default processing */
>   		default:
>   default_handle:
>   			error = kgdb_arch_handle_exception(ks->ex_vector,
>