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From: "H. Peter Anvin" <hpa@zytor.com>
To: Ingo Molnar <mingo@elte.hu>
Cc: Andres Salomon <dilinger@queued.net>,
	Milton Miller <miltonm@bga.com>,
	Grant Likely <grant.likely@secretlab.ca>,
	devicetree-discuss@lists.ozlabs.org,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH 3/3] x86: OLPC: speed up device tree creation during boot (v2)
Date: Mon, 15 Nov 2010 09:43:15 -0800	[thread overview]
Message-ID: <4CE17133.2050101@zytor.com> (raw)
In-Reply-To: <20101115070254.GA25243@elte.hu>

On 11/14/2010 11:02 PM, Ingo Molnar wrote:
> 
> * H. Peter Anvin <hpa@zytor.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.


WARNING: multiple messages have this Message-ID (diff)
From: "H. Peter Anvin" <hpa-YMNOUZJC4hwAvxtiuMwx3w@public.gmane.org>
To: Ingo Molnar <mingo-X9Un+BFzKDI@public.gmane.org>
Cc: devicetree-discuss-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org,
	linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	Milton Miller <miltonm-ogEGBHC/i9Y@public.gmane.org>,
	Ingo Molnar <mingo-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>,
	Andres Salomon <dilinger-pFFUokh25LWsTnJN9+BGXg@public.gmane.org>,
	Thomas Gleixner <tglx-hfZtesqFncYOwBW4kG4KsQ@public.gmane.org>
Subject: Re: [PATCH 3/3] x86: OLPC: speed up device tree creation during boot (v2)
Date: Mon, 15 Nov 2010 09:43:15 -0800	[thread overview]
Message-ID: <4CE17133.2050101@zytor.com> (raw)
In-Reply-To: <20101115070254.GA25243-X9Un+BFzKDI@public.gmane.org>

On 11/14/2010 11:02 PM, Ingo Molnar wrote:
> 
> * H. Peter Anvin <hpa-YMNOUZJC4hwAvxtiuMwx3w@public.gmane.org> 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.

  reply	other threads:[~2010-11-15 17:43 UTC|newest]

Thread overview: 30+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-11-12  5:45 [PATCH 3/3] x86: OLPC: speed up device tree creation during boot (v2) Andres Salomon
2010-11-12  5:45 ` Andres Salomon
2010-11-12  7:48 ` Milton Miller
2010-11-12  7:48   ` Milton Miller
2010-11-12  8:27   ` Andres Salomon
2010-11-12  8:27     ` Andres Salomon
2010-11-14  9:50     ` Ingo Molnar
2010-11-15  4:21       ` H. Peter Anvin
2010-11-15  4:21         ` H. Peter Anvin
2010-11-15  7:02         ` Ingo Molnar
2010-11-15  7:02           ` Ingo Molnar
2010-11-15 17:43           ` H. Peter Anvin [this message]
2010-11-15 17:43             ` H. Peter Anvin
2010-11-17  6:12             ` [PATCH 3/3] x86: OLPC: speed up device tree creation during boot (v3) Andres Salomon
2010-11-17  6:12               ` Andres Salomon
2010-11-29 23:39               ` [PATCH 3/3] x86: OLPC: speed up device tree creation during boot (v4) Andres Salomon
2010-12-16  2:58                 ` [tip:x86/olpc] x86, olpc: Speed up device tree creation during boot tip-bot for Andres Salomon
2010-11-18  8:34             ` [PATCH 3/3] x86: OLPC: speed up device tree creation during boot (v2) Ingo Molnar
2010-11-18  8:34               ` Ingo Molnar
2010-11-18 11:02               ` Michael Ellerman
2010-11-18 11:02                 ` Michael Ellerman
2010-11-18 15:04                 ` H. Peter Anvin
2010-11-18 15:04                   ` H. Peter Anvin
2010-11-18 17:41                   ` Andres Salomon
2010-11-18 17:41                     ` Andres Salomon
2010-11-18 17:48                     ` H. Peter Anvin
2010-11-18 17:48                       ` H. Peter Anvin
2010-11-19 20:24                       ` Andres Salomon
2010-11-19 20:24                         ` Andres Salomon
2010-12-23 11:57               ` Ingo Molnar

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