Re: Regression with commit f9cde5f in 2.6.30-gitX

Jaswinder Singh Rajput
2009-06-24T16:16:27Z

On Wed, 2009-06-24 at 08:56 -0700, Gary Hade wrote:
> On Wed, Jun 24, 2009 at 04:51:48PM +0200, Thomas Gleixner wrote:
> > On Wed, 24 Jun 2009, Jaswinder Singh Rajput wrote:
> > > Reported-by: Larry Finger <Larry.Finger@lwfinger.net>
> > > Signed-off-by: Jaswinder Singh Rajput <jaswinderrajput@gmail.com>
> > > ---
> > > arch/x86/pci/acpi.c | 16 ++++++++++------
> > > 1 files changed, 10 insertions(+), 6 deletions(-)
> > >
> > > diff --git a/arch/x86/pci/acpi.c b/arch/x86/pci/acpi.c
> > > index 16c3fda..0bc015f 100644
> > > --- a/arch/x86/pci/acpi.c
> > > +++ b/arch/x86/pci/acpi.c
> > > @@ -69,6 +69,9 @@ setup_resource(struct acpi_resource *acpi_res, void *data)
> > > struct resource *root;
> > > int max_root_bus_resources = PCI_BUS_NUM_RESOURCES;
> > >
> > > + if (info->res_num >= PCI_BUS_NUM_RESOURCES)
> > > + return AE_OK;
> > > +
> > > status = resource_to_addr(acpi_res, &addr);
> > > if (!ACPI_SUCCESS(status))
> > > return AE_OK;
> > > @@ -94,17 +97,18 @@ setup_resource(struct acpi_resource *acpi_res, void *data)
> > > if (bus_has_transparent_bridge(info->bus))
> > > max_root_bus_resources -= 3;
> > > if (info->res_num >= max_root_bus_resources) {
> > > - printk(KERN_WARNING "PCI: Failed to allocate 0x%lx-0x%lx "
> > > - "from %s for %s due to _CRS returning more than "
> > > - "%d resource descriptors\n", (unsigned long) res->start,
> > > - (unsigned long) res->end, root->name, info->name,
> > > - max_root_bus_resources);
> > > + pr_warning("PCI: Failed to allocate 0x%lx-0x%lx "
> > > + "from %s for %s due to _CRS returning more than "
> > > + "%d resource descriptors\n",
> > > + (unsigned long)res->start, (unsigned long)res->end,
> > > + root->name, info->name, max_root_bus_resources);
> >
> > Can you please avoid mixing cleanup patches with bug fixes ? I almost
> > did not see the line below.
> >
> > > + info->bus->resource[info->res_num] = res;
> >
> > Storing the resource in defeats the purpose of the original patch,
> > which makes sure that we do _NOT_ use the last 3 slots of the resource
> > array for a root bus with a transparent bridge.
> >
> > > info->res_num++;
> >
> > This is the real bug. info->res_num should not be incremented when we
> > run out of resources already.
>
> This probably isn't needed but I don't think it is the cause of
> the problem. It is just counting the number of _CRS returned
> resources and I believe subsequent visits to setup_resource()
> for additional returned resources will generate the same warning
> as it also would if the instruction were removed and no longer
> being used to keep an accurate count.
>

Yes, this count is needed to avoid PCI failure.

Thanks,
--
JSR