linux-kernel - Re: [PATCH] x86/pci/mrst: add extra check in fixed bar detection

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Message-ID: <4C45DA7F.1060801@candelatech.com>
Date:	Tue, 20 Jul 2010 10:18:55 -0700
From:	Ben Greear <greearb@...delatech.com>
To:	Jacob Pan <jacob.jun.pan@...ux.intel.com>
CC:	"H. Peter Anvin" <hpa@...or.com>,
	Jesse Barnes <jbarnes@...tuousgeek.org>,
	LKML <linux-kernel@...r.kernel.org>, Greg KH <greg@...ah.com>
Subject: Re: [PATCH] x86/pci/mrst: add extra check in fixed bar detection

On 07/16/2010 11:58 AM, Jacob Pan wrote:
> Fixed bar capability structure is searched in PCI extended configuration
> space. We need to make sure there is a valid capability id to begin with
> otherwise, the search code may stuck in a infinite loop which results in
> boot hang.
> This patch adds additional check for cap ID 0, which is also invalid.

I think this should be added to the stable tree for 2.6.34
as well...

Thanks,
Ben

>
> Suggested-by: "H. Peter Anvin"<hpa@...or.com>
>
> Signed-off-by: Jacob Pan<jacob.jun.pan@...ux.intel.com>
> ---
>   arch/x86/pci/mrst.c |    7 ++++---
>   1 files changed, 4 insertions(+), 3 deletions(-)
>
> diff --git a/arch/x86/pci/mrst.c b/arch/x86/pci/mrst.c
> index c9649d0..8636567 100644
> --- a/arch/x86/pci/mrst.c
> +++ b/arch/x86/pci/mrst.c
> @@ -66,8 +66,9 @@ static int fixed_bar_cap(struct pci_bus *bus, unsigned int devfn)
>   					  devfn, pos, 4,&pcie_cap))
>   			return 0;
>
> -		if (pcie_cap == 0xffffffff)
> -			return 0;
> +		if (PCI_EXT_CAP_ID(pcie_cap) == 0x0000 ||
> +			PCI_EXT_CAP_ID(pcie_cap) == 0xffff)
> +			break;
>
>   		if (PCI_EXT_CAP_ID(pcie_cap) == PCI_EXT_CAP_ID_VNDR) {
>   			raw_pci_ext_ops->read(pci_domain_nr(bus), bus->number,
> @@ -76,7 +77,7 @@ static int fixed_bar_cap(struct pci_bus *bus, unsigned int devfn)
>   				return pos;
>   		}
>
> -		pos = pcie_cap>>  20;
> +		pos = PCI_EXT_CAP_NEXT(pcie_cap);
>   	}
>
>   	return 0;


-- 
Ben Greear <greearb@...delatech.com>
Candela Technologies Inc  http://www.candelatech.com

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