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From: David Woodhouse <dwmw2@infradead.org>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Alan <alan@lxorguk.ukuu.org.uk>, Jeff Garzik <jgarzik@pobox.com>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] libata-sff: Don't call bmdma_stop on non DMA capable controllers
Date: Fri, 26 Jan 2007 13:09:40 +0800	[thread overview]
Message-ID: <1169788181.3593.250.camel@shinybook.infradead.org> (raw)
In-Reply-To: <Pine.LNX.4.64.0701252029570.25027@woody.linux-foundation.org>

On Thu, 2007-01-25 at 20:48 -0800, Linus Torvalds wrote:
> Irq0 may _exist_. IO Port 0 may _exist_. Virtual address 0 may
> _exist_. 
> 
> Got it?
> 
> But they ARE NOT VALID THINGS FOR DRIVERS TO WORRY ABOUT.

I do understand what you're saying; there's no need to shout. I think
it's very misguided and leads to both internal inconsistency (as
demonstrated by the setup_irq() patch) and external inconsistency with
stuff like hardware documentation. But I _do_ understand what you're
saying.

> When a *DRIVER* sees a [zero], it's always a sign of "not here".

Except when it isn't. Like when it's a DMA address. Or a file
descriptor. Or a CPU number. Or one of numerous other things.

But still, I do understand what you're saying although I disagree with
your intention and your statement above is plain wrong (well, at least
my misquote of it is wrong -- you actually said 'NULL' which is fair
enough, but in the middle of a rant about _zero_ so I edited the quote
to say zero because that's what we're actually talking about).

> But they ARE NOT VALID THINGS FOR DRIVERS TO WORRY ABOUT.
 ...
> NO NORMAL USER SHOULD EVER SEE [zero] AS A REAL IO PORT. 

Yes, that much I understand. We disagree, but I understand you. My last
response was not intending to pursue that part of the discussion.

My question was about _how_ you think this should be achieved in this
particular case. You didn't like the suggestion that we should put your
new special-case hack into the resource code... where/how _do_ you
suggest that it's done, so that we can protect those poor driver authors
from the number zero?

-- 
dwmw2


  reply	other threads:[~2007-01-26  5:10 UTC|newest]

Thread overview: 33+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-01-25 15:09 Alan
2007-01-25 16:14 ` David Woodhouse
2007-01-25 16:17   ` Jeff Garzik
2007-01-25 16:19     ` David Woodhouse
2007-01-25 16:22     ` Russell King
2007-01-25 16:26       ` David Woodhouse
2007-01-25 17:27   ` Alan
2007-01-25 17:56     ` Linus Torvalds
2007-01-26  0:23       ` David Woodhouse
2007-01-26  1:28         ` Linus Torvalds
2007-01-26  1:45           ` Jeff Garzik
2007-01-26  2:01             ` Linus Torvalds
2007-01-26  2:11               ` Jeff Garzik
2007-01-26 10:37               ` Alan
2007-01-28 23:01               ` Benjamin Herrenschmidt
2007-01-28 22:57             ` Benjamin Herrenschmidt
2007-01-26  2:23           ` David Woodhouse
2007-01-26  2:58             ` Linus Torvalds
2007-01-26  3:28               ` David Woodhouse
2007-01-26  4:00                 ` Linus Torvalds
2007-01-26  4:19                   ` David Woodhouse
2007-01-26  4:48                     ` Linus Torvalds
2007-01-26  5:09                       ` David Woodhouse [this message]
2007-01-26  6:01                         ` Linus Torvalds
2007-01-26  6:18                           ` Linus Torvalds
2007-01-26  8:17                             ` David Miller
2007-01-26  8:20                         ` David Miller
2007-01-26  4:53                 ` Jeff Garzik
2007-01-26 15:32                 ` Mark Lord
2007-01-26 15:29               ` Mark Lord
2007-01-28 23:04               ` Benjamin Herrenschmidt
2007-01-28 22:49       ` Benjamin Herrenschmidt
2007-01-25 23:36 ` Jeff Garzik

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