linux-kernel - Re: [PATCH] afs: fix no return statement in function returning non-void

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Message-ID: <f2764b10-dd0d-cabf-0264-131ea5829fed@infradead.org>
Date:   Tue, 15 Jun 2021 16:58:01 -0700
From:   Randy Dunlap <rdunlap@...radead.org>
To:     Linus Torvalds <torvalds@...ux-foundation.org>,
        David Howells <dhowells@...hat.com>
Cc:     Hulk Robot <hulkci@...wei.com>,
        Zheng Zengkai <zhengzengkai@...wei.com>,
        Tom Rix <trix@...hat.com>, linux-afs@...ts.infradead.org,
        Marc Dionne <marc.dionne@...istor.com>,
        linux-fsdevel <linux-fsdevel@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] afs: fix no return statement in function returning
 non-void

On 6/15/21 7:49 AM, Linus Torvalds wrote:
> On Tue, Jun 15, 2021 at 4:55 AM David Howells <dhowells@...hat.com> wrote:
>>
>> From: Zheng Zengkai <zhengzengkai@...wei.com>
>>
>> Add missing return to fix following compilation issue:
>>
>> fs/afs/dir.c: In function ‘afs_dir_set_page_dirty’:
>> fs/afs/dir.c:51:1: error: no return statement in function
>> returning non-void [-Werror=return-type]
> 
> This warning is actively wrong, and the patch is the wrong thing to do.
> 
> What compiler / architecture / config?
> 
> Because BUG() should have an "unreachable()", and the compiler should
> know that a return statement isn't needed (and adding it shouldn't
> make any difference).
> 
> And it's not warning for me when I build that code. So I really think
> the real bug is entirely somewhere else, and this patch is papering
> over the real problem.

Hi,

Some implementations of BUG() are macros, not functions, so "unreachable"
is not applicable AFAIK.


-- 
~Randy