Re: [PATCH 0/1] Recurse when searching for empty slots inresources trees

From: Matthew Wilcox
Date: Wed Jun 17 2009 - 09:43:34 EST

On Wed, Jun 17, 2009 at 06:13:24PM +0900, Kenji Kaneshige wrote:
> I think the reason why it happen is ia64 (I believe you are using
> ia64 environment) uses pci_claim_resource(), which calls
> insert_resource(), to insert resources. In my understanding, if
> two resources having an identical address range are inserted using
> insert_resource(), the latter one becomes parent of the first one.
> I made a sample patch, though I don't know if it fixes the problem.
> I hope this would help you. But please note that it is NOT well
> tested.

This patch seems to be saying that it's ia64's fault for using
pci_claim_resource. Surely pci_claim_resource() is buggy and is the
right place to fix the problem (other users include alpha, mn10300,
powerpc and parisc).

This all kind of begs the question why x86 isn't using
pci_claim_resource(); if it were, bugs like this would be found and
fixed earlier.

It further begs the question why architectures are doing this in the
first place. All PCI device resources should be in /proc/iomem, no
matter what architecture.

Anyway, this should fix pci_claim_resource (untested):

Signed-off-by: Matthew Wilcox <willy@xxxxxxxxxxxxxxx>

diff --git a/drivers/pci/setup-res.c b/drivers/pci/setup-res.c
index 3039fcb..1240351 100644
--- a/drivers/pci/setup-res.c
+++ b/drivers/pci/setup-res.c
@@ -99,11 +99,11 @@ void pci_update_resource(struct pci_dev *dev, int resno)
int pci_claim_resource(struct pci_dev *dev, int resource)
struct resource *res = &dev->resource[resource];
- struct resource *root = NULL;
+ struct resource *root;
char *dtype = resource < PCI_BRIDGE_RESOURCES ? "device" : "bridge";
int err;

- root = pcibios_select_root(dev, res);
+ root = pci_find_parent_resource(dev, res);

err = -EINVAL;
if (root != NULL)

Matthew Wilcox Intel Open Source Technology Centre
"Bill, look, we understand that you're interested in selling us this
operating system, but compare it to ours. We can't possibly take such
a retrograde step."
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