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

From: Ben Greear
Date: Tue Jul 20 2010 - 13:19:09 EST


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@xxxxxxxxx>

Signed-off-by: Jacob Pan<jacob.jun.pan@xxxxxxxxxxxxxxx>
---
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@xxxxxxxxxxxxxxx>
Candela Technologies Inc http://www.candelatech.com

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