linux-hardening - Re: [PATCH 032/141] floppy: Fix fall-through warnings for Clang

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Message-ID: <47bcd36a-6524-348b-e802-0691d1b3c429@kernel.dk>
Date:   Tue, 20 Apr 2021 14:30:29 -0600
From:   Jens Axboe <axboe@...nel.dk>
To:     "Gustavo A. R. Silva" <gustavo@...eddedor.com>,
        "Gustavo A. R. Silva" <gustavoars@...nel.org>,
        Denis Efremov <efremov@...ux.com>
Cc:     linux-block@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-hardening@...r.kernel.org
Subject: Re: [PATCH 032/141] floppy: Fix fall-through warnings for Clang

On 4/20/21 2:25 PM, Gustavo A. R. Silva wrote:
> Hi all,
> 
> Friendly ping: who can take this, please?
> 
> Thanks
> --
> Gustavo
> 
> On 11/20/20 12:28, Gustavo A. R. Silva wrote:
>> In preparation to enable -Wimplicit-fallthrough for Clang, fix a warning
>> by explicitly adding a fallthrough pseudo-keyword in places where the
>> code is intended to fall through to the next case.
>>
>> Link: https://github.com/KSPP/linux/issues/115
>> Signed-off-by: Gustavo A. R. Silva <gustavoars@...nel.org>
>> ---
>>  drivers/block/floppy.c | 1 +
>>  1 file changed, 1 insertion(+)
>>
>> diff --git a/drivers/block/floppy.c b/drivers/block/floppy.c
>> index 7df79ae6b0a1..21a2a7becba0 100644
>> --- a/drivers/block/floppy.c
>> +++ b/drivers/block/floppy.c
>> @@ -2124,6 +2124,7 @@ static void format_interrupt(void)
>>  	switch (interpret_errors()) {
>>  	case 1:
>>  		cont->error();
>> +		fallthrough;
>>  	case 2:
>>  		break;
>>  	case 0:

I wonder about the consistency of the patches. The one I just applied
for libata adds a break, this one annotates fallthrough. But the cases
are really 100% the same. Why aren't the changes consistent? Both are
obviously fine, but for identical cases it seems odd that they differ.

IMHO, adding a break makes more sense. Annotate the fallthrough if the
two cases share work that needs to be done, as then that solution makes
sense.

-- 
Jens Axboe