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

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Message-ID: <9b296479-dd9b-7ad3-91c2-32976ce146be@embeddedor.com>
Date:   Tue, 26 Feb 2019 14:59:31 -0600
From:   "Gustavo A. R. Silva" <gustavo@...eddedor.com>
To:     Jason Wessel <jason.wessel@...driver.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



On 2/26/19 2:47 PM, Jason Wessel wrote:
> We'll have to fix them at some point.
> 

Yep. And we're about to fix them all.

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

Thanks, Jason.

--
Gustavo

> 
> 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,
>>
>