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

From: Matthew Wilcox
Date: Wed Jun 17 2009 - 16:17:40 EST

On Wed, Jun 17, 2009 at 01:12:42PM -0700, Linus Torvalds wrote:
> On Wed, 17 Jun 2009, Andrew Patterson wrote:
> > >
> > > This is why I'd really like to see the output of my test-patch. It would
> > > show exactly _where_ that resource is inserted, and the whole call-chain.
> > >
> > > I'm appending a version that only does it for resources that have names
> > > starting with "PCI Bus", so it should be less noisy. But again, it's
> > > totally untested.
> > >
> >
> > Here you go (I can provide the full boot log if needed). Note, there is
> > nothing for c3 here:
> Ok, so that means it got inserted into the resource tree some other way
> entirely. Or maybe the name got changed after-the-fact. Both of which
> imply that something is really really wrong.


> The ones your trace _does_ show are the ones that got inserted correctly
> and aren't buggy. Can anybody see how that buggy resource got inserted?

Carefully studying the results of git grep insert_resource doesn't show
too many options. Most are in code which doesn't get executed on ia64.
add_window is the only one which looks even remotely plausible, and
that's only supposed to be called for root bridges.

I did notice that pcibios_setup_root_windows() is being called too late.
It's currently called after pci_scan_bus_parented() when it needs to be
called from pcibios_fixup_bus() [ie during the scan_bus, before child
busses are scanned].

Andrew's currently testing this patch:

diff --git a/arch/ia64/pci/pci.c b/arch/ia64/pci/pci.c
index 61f1af5..ae5ee8a 100644
--- a/arch/ia64/pci/pci.c
+++ b/arch/ia64/pci/pci.c
@@ -371,8 +371,6 @@ pci_acpi_scan_root(struct acpi_device *device, int domain, int bus)
* such quirk. So we just ignore the case now.
pbus = pci_scan_bus_parented(NULL, bus, &pci_root_ops, controller);
- if (pbus)
- pcibios_setup_root_windows(pbus, controller);

return pbus;

@@ -490,6 +488,8 @@ pcibios_fixup_bus (struct pci_bus *b)
if (b->self) {
+ } else {
+ pcibios_setup_root_windows(b, b->sysdata);
list_for_each_entry(dev, &b->devices, bus_list)

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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