linux-kernel - Re: [PATCH 03/11] pci: reject mmio range start from 0 on pci

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Message-ID: <20100116042010.GD22215@ldl.fc.hp.com>
Date:	Fri, 15 Jan 2010 21:20:10 -0700
From:	Alex Chiang <achiang@...com>
To:	Yinghai Lu <yinghai@...nel.org>
Cc:	Jesse Barnes <jbarnes@...tuousgeek.org>,
	Ingo Molnar <mingo@...e.hu>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Ivan Kokshaysky <ink@...assic.park.msu.ru>,
	Kenji Kaneshige <kaneshige.kenji@...fujitsu.com>,
	Bjorn Helgaas <bjorn.helgaas@...com>,
	linux-kernel@...r.kernel.org, linux-pci@...r.kernel.org
Subject: Re: [PATCH 03/11] pci: reject mmio range start from 0 on
	pci_bridge read

Please change title of patch to:

	pci: pci_read_bridge_bases rejects MMIO ranges starting at 0

* Yinghai Lu <yinghai@...nel.org>:
> that is wrong.
> 
> exposed by that patch that doesn's shrink pci bridge res.

Ok, I don't understand how this patch interacts with patch 4/11.
Am I correct in understanding that something in 4/11 exposes a
problem that 3/11 fixes?

I'm just looking for a better explanation of *why* we need this
patch here.

> -v2: change to "bar reading" to "reg reading"
> 
> Signed-off-by: Yinghai Lu <yinghai@...nel.org>
> ---
>  drivers/pci/probe.c |   18 +++++++++++++++---
>  1 files changed, 15 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
> index 11824d7..70b1f74 100644
> --- a/drivers/pci/probe.c
> +++ b/drivers/pci/probe.c
> @@ -316,13 +316,17 @@ void __devinit pci_read_bridge_bases(struct pci_bus *child)
>  		limit |= (io_limit_hi << 16);
>  	}
>  
> -	if (base <= limit) {
> +	if (base <= limit && base) {

This construct (and the similar one below) is a little
non-idiomatic.

	if (base && base <= limit)

reads a lot more naturally to me.

thanks,
/ac
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