linux-kernel - Re: [PATCH v2 8/9] bfs: remove multiple assignments

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Date:	Wed, 30 Jan 2008 16:36:54 +0300
From:	Dmitri Vorobiev <dmitri.vorobiev@...il.com>
To:	Al Viro <viro@...IV.linux.org.uk>
CC:	Joel Schopp <jschopp@...tin.ibm.com>,
	Dmitri Vorobiev <dmitri.vorobiev@...il.com>,
	Tigran Aivazian <tigran@...azian.fsnet.co.uk>,
	trivial@...nel.org, linux-fsdevel@...r.kernel.org,
	apw@...dowen.org, rdunlap@...otime.net,
	Linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 8/9] bfs: remove multiple assignments

Al Viro wrote:
> On Mon, Jan 28, 2008 at 01:02:03AM -0600, Joel Schopp wrote:
>>>>> -    inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME_SEC;
>>>>> +    inode->i_mtime = CURRENT_TIME_SEC;
>>>>> +    inode->i_atime = CURRENT_TIME_SEC;
>>>>> +    inode->i_ctime = CURRENT_TIME_SEC;
>>>> multiple assignments like "x = y = z = value;" can potentially
>>>> (depending on the compiler and arch) be faster than "x = value; y =
>>>> value; z=value;"
>>>>
>>>> I am surprized that this script complains about them as it is a
>>>> perfectly valid thing to do in C.
>>> I think it seems wise to ask the maintainers of checkpatch.pl to
>>> comment on that. I'm Cc:ing them now.
>>>
>> There are plenty of things that are valid to do in C that don't make for 
>> maintainable code.  These scripts are designed to make your code easier for 
>> real people to review and maintain.
> 
> Except that in this case the new variant is not equivalent to the old one...

Yes, you're right. In fact, I felt like sending yet another version
of these patches, but this gets preempted all the time by "the other things".

Dmitri
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