linux-kernel - Re: [PATCH] nfs: remove incorrect fallthrough label

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Date:   Tue, 15 Sep 2020 19:01:14 -0500
From:   "Gustavo A. R. Silva" <gustavo@...eddedor.com>
To:     Joe Perches <joe@...ches.com>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Trond Myklebust <trond.myklebust@...merspace.com>,
        Anna Schumaker <anna.schumaker@...app.com>
Cc:     Nathan Chancellor <natechancellor@...il.com>,
        Miaohe Lin <linmiaohe@...wei.com>,
        Hongxiang Lou <louhongxiang@...wei.com>,
        linux-nfs@...r.kernel.org, linux-kernel@...r.kernel.org,
        clang-built-linux@...glegroups.com
Subject: Re: [PATCH] nfs: remove incorrect fallthrough label



On 9/15/20 18:51, Gustavo A. R. Silva wrote:
> 
> 
> On 9/15/20 18:29, Joe Perches wrote:
>> On Tue, 2020-09-15 at 15:57 -0700, Nick Desaulniers wrote:
>>> There is no case after the default from which to fallthrough to. Clang
>>> will error in this case (unhelpfully without context, see link below)
>>> and GCC will with -Wswitch-unreachable.
>>>
>>> The previous commit should have just removed the comment.
>> []
>>> diff --git a/fs/nfs/super.c b/fs/nfs/super.c
>> []
>>> @@ -889,7 +889,6 @@ static struct nfs_server *nfs_try_mount_request(struct fs_context *fc)
>>>  		default:
>>>  			if (rpcauth_get_gssinfo(flavor, &info) != 0)
>>>  				continue;
>>> -			fallthrough;
>>
>> My preference would be to convert the fallthrough
>> to a break here so if someone ever adds another
>> label after default: for any reason, the code would
>> still work as expected.
> 
> I agree with Joe.

Actually, this is part of the work I plan to do to enable -Wimplicit-fallthrough
for Clang: audit every place where we could use a break instead of a fallthrough.

I'm on vacation this week. So, I'll get back to this next week.

Thanks
--
Gustavo