linux-kernel - Re: [PATCH] shm: Remove silly double assignment

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Message-ID: <20080618100624.GE15255@elte.hu>
Date:	Wed, 18 Jun 2008 12:06:24 +0200
From:	Ingo Molnar <mingo@...e.hu>
To:	Neil Horman <nhorman@...driver.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org, mingo@...hat.com,
	torvalds@...ux-foundation.org
Subject: Re: [PATCH] shm: Remove silly double assignment


* Neil Horman <nhorman@...driver.com> wrote:

> > Not silly, really.  Look:
> > 
> > 	err = -ENOMEM;
> > 	if (expr1)
> > 		goto out;
> > 
> > 	err = -ENOMEM;
> > 	if (expr2)
> > 		goto out;
> > 
> > each of these two units is a separate, self-contained clause.  
> > Removing the second assignment to `err' breaks that separation and 
> > will make one clause undesirably dependent upon the other.
>
> yes, I see that keeping the second assignment lets you insert code in 
> the middle without having up to update afterwards.  I just don't think 
> the redundant assignment is worth keeping just for that purpose.

cleanups is all about having familar, robust, predictable, 
self-contained patterns of code that are easy to recognize, easy to 
review and easy to keep working well.

In this case we've got an admittedly boundary case: removing the 
technically redundant piece of code, while a valid cleanup at first 
sight, makes the code less robust against future changes.

	Ingo
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