linux-kernel - Re: [PATCH 3/3] x86: OLPC: speed up device tree creation during boot (v2)

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Message-ID: <4CE17133.2050101@zytor.com>
Date:	Mon, 15 Nov 2010 09:43:15 -0800
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Ingo Molnar <mingo@...e.hu>
CC:	Andres Salomon <dilinger@...ued.net>,
	Milton Miller <miltonm@....com>,
	Grant Likely <grant.likely@...retlab.ca>,
	devicetree-discuss@...ts.ozlabs.org,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/3] x86: OLPC: speed up device tree creation during boot
 (v2)

On 11/14/2010 11:02 PM, Ingo Molnar wrote:
> 
> * H. Peter Anvin <hpa@...or.com> wrote:
> 
>> What?  What is wrong with static variables in functions?  It really doesn't seem 
>> to be a good idea to make them file-scope if they don't need to be.
> 
> They are very easy to overlook and mix up with regular stack variables and i've seen 
> (and introduced myself) a number of bugs due to them.
> 
> They also often are used in buggy ways (with SMP not taken into consideration), so 
> overlooking them during review compounds their negative effects. Putting them in 
> front of the function isnt a big deal in exchange.
> 
> There are people who never overlook them (like yourself), but my brain is wired up 
> differently.
> 

However, I have to vehemently object to putting them in a wider scope
than is otherwise necessary.  I agree that static variables should be
used sparsely if at all (there really are vary few uses of them that are
valid), but putting them in a larger scope screams "I'm used in more
than one function", and that is *not* a good thing.

	-hpa

-- 
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel.  I don't speak on their behalf.

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