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

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Message-ID: <331c6c2c-2374-3ce4-5940-2adc0e4b94a2@embeddedor.com>
Date:   Wed, 15 Aug 2018 09:43:46 -0500
From:   "Gustavo A. R. Silva" <gustavo@...eddedor.com>
To:     Daniel Thompson <daniel.thompson@...aro.org>,
        Jason Wessel <jason.wessel@...driver.com>
Cc:     kgdb-bugreport@...ts.sourceforge.net, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] kdb: kdb_main: mark expected switch fall-throughs

Hi Daniel,

On 8/15/18 9:34 AM, Daniel Thompson wrote:
> On 05/08/18 05:14, Gustavo A. R. Silva wrote:
>> In preparation to enabling -Wimplicit-fallthrough, mark switch cases
>> where we are expecting to fall through.
>>
>> Addresses-Coverity-ID: 115090 ("Missing break in switch")
>> Addresses-Coverity-ID: 115091 ("Missing break in switch")
>> Addresses-Coverity-ID: 114700 ("Missing break in switch")
>> Signed-off-by: Gustavo A. R. Silva <gustavo@...eddedor.com>
> 
> Adding fall through isn't wrong but its reasonable to ask why there is a complex hand unrolled loop here in the first place (and doubly so without a comment). The whole switch statement would be much clear expressed as:
> 
>     for (j=0; j<bytesperword; j++)
>         *c++ = printable_char(*cp++);
>     addr += bytesperword;
> 

Yeah, I agree. I can send a patch for that.

Thanks for the feedback.
--
Gustavo

> 
> Daniel.
> 
> 
>> ---
>>   kernel/debug/kdb/kdb_main.c | 3 +++
>>   1 file changed, 3 insertions(+)
>>
>> diff --git a/kernel/debug/kdb/kdb_main.c b/kernel/debug/kdb/kdb_main.c
>> index 2ddfce8..2249645 100644
>> --- a/kernel/debug/kdb/kdb_main.c
>> +++ b/kernel/debug/kdb/kdb_main.c
>> @@ -1545,13 +1545,16 @@ static void kdb_md_line(const char *fmtstr, unsigned long addr,
>>                   *c++ = printable_char(*cp++);
>>                   *c++ = printable_char(*cp++);
>>                   addr += 4;
>> +                /* fall through */
>>               case 4:
>>                   *c++ = printable_char(*cp++);
>>                   *c++ = printable_char(*cp++);
>>                   addr += 2;
>> +                /* fall through */
>>               case 2:
>>                   *c++ = printable_char(*cp++);
>>                   addr++;
>> +                /* fall through */
>>               case 1:
>>                   *c++ = printable_char(*cp++);
>>                   addr++;
>>
>