linux-kernel - Re: [PATCH 5/9] bfs: move function prototype to the proper header file

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Thu, 24 Jan 2008 20:55:47 -0500
From:	Kyle Moffett <kyle@...fetthome.net>
To:	Dmitri Vorobiev <dmitri.vorobiev@...il.com>
Cc:	Heikki Orsila <shdl@...alwe.fi>, trivial@...nel.org,
	linux-kernel@...r.kernel.org, akpm@...ux-foundation.org,
	tigran@...azian.fsnet.co.uk
Subject: Re: [PATCH 5/9] bfs: move function prototype to the proper header file

On Jan 24, 2008, at 18:13, Dmitri Vorobiev wrote:
> Heikki Orsila пишет:
>> On Fri, Jan 25, 2008 at 01:32:04AM +0300, Dmitri Vorobiev wrote:
>>> +/* inode.c */
>>> +extern void dump_imap(const char *, struct super_block *);
>>> +
>>
>> Functions should not be externed, remove extern keyword.
>
> Care to explain why?
>
> Following is an explanation why the contrary is probably true:
>
> 1) We have lots of precedents in existing code:
>
> dmvo@...her:~/Projects/misc/linux$ git-grep 'extern void' include |  
> wc -l
> 5523
> dmvo@...her:~/Projects/misc/linux$


The "extern" keyword on functions is *completely* redundant.

For C variables:
   Declaration:  extern int foo;
   Definition:   int foo;
   File-scoped:  static int foo;

For C functions:
   Declaration:  void foo(int x);
   Definition:   void foo(int x) { /*...body...*/ }
   File-scoped:  static void foo(int x) { /*...body...*/ }

The compiler will *allow* you to use "extern" on the function  
prototype, but the presence or absence of a function body is  
sufficiently obvious for it to determine whether the prototype is a  
declaration or a definition that the "extern" keyword is not required  
and therefore redundant.

For maximum readability and cleanliness I recommend that you leave off  
the "extern" on the function declarations; it makes the lines much  
longer without obvious gain.

Cheers,
Kyle Moffett


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/