linux-kernel - Re: [PATCH] sysctl.c: Change a .proc_handler = proc_dointvec to &proc

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Date:	Sun, 15 Nov 2009 02:04:23 -0800
From:	ebiederm@...ssion.com (Eric W. Biederman)
To:	Ingo Molnar <mingo@...e.hu>
Cc:	Joe Perches <joe@...ches.com>,
	Am??rico Wang <xiyou.wangcong@...il.com>,
	LKML <linux-kernel@...r.kernel.org>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH] sysctl.c: Change a .proc_handler = proc_dointvec to &proc_dointvec,

Ingo Molnar <mingo@...e.hu> writes:

> * Joe Perches <joe@...ches.com> wrote:
>
>> On Sun, 2009-11-15 at 09:11 +0100, Ingo Molnar wrote:
>> > * Am??rico Wang <xiyou.wangcong@...il.com> wrote:
>> > > On Sat, Nov 14, 2009 at 05:52:05PM -0800, Joe Perches wrote:
>> > > >Seems to be a typo.
>> > > Acked-by: WANG Cong <xiyou.wangcong@...il.com>
>> > (Cc:-ed Eric who is running the sysctl tree these days)
>> > Almost everywhere in the kernel we use the shorter version, so all of 
>> > sysctl.c should eventually change to that variant.
>> 
>> It's closer to 50/50, but it's 1 vs 133 in that file.
>> 
>> $ grep -Pr --include=*.[ch] '\.proc_handler\s*=\s*&\s*\w+' * | wc -l
>> 339
>> 
>> $ grep -Pr --include=*.[ch] '\.proc_handler\s*=\s*[^&]\s*\w+' * | wc -l
>> 432
>
> I did not mean this specific initialization method of proc_handler, i 
> meant pointers to functions in general.


There was an argument put forward by Alexy (I think) a while ago.  That
argued for the form without the address of operator.

The reason being that without it you can do:
#define proc_dointvec NULL

in a header when sysctl support it compiled out.  Using address of
you wind up with stub functions in sysctl.c to handle the case when
sysctl is compiled out.

It isn't a strong case but since not using & is also shorter and
as Ingo pointed out more common I think no & wins.

Eric
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