[ 045/122] PCI: Check P2P bridge for invalid secondary/subordinate range

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

3.6-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Yinghai Lu <yinghai@kernel.org>

commit 1965f66e7db08d1ebccd24a59043eba826cc1ce8 upstream.

For bridges with "secondary > subordinate", i.e., invalid bus number
apertures, we don't enumerate anything behind the bridge unless the
user specified "pci=assign-busses".

This patch makes us automatically try to reassign the downstream bus
numbers in this case (just for that bridge, not for all bridges as
"pci=assign-busses" does).

We don't discover all the devices on the Intel DP43BF motherboard
without this change (or "pci=assign-busses") because its BIOS configures
a bridge as:

    pci 0000:00:1e.0: PCI bridge to [bus 20-08] (subtractive decode)

[bhelgaas: changelog, change message to dev_info]
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=18412
Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=625754
Reported-by: Brian C. Huffman <bhuffman@graze.net>
Reported-by: VL <vl.homutov@gmail.com>
Tested-by: VL <vl.homutov@gmail.com>
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

---
 drivers/pci/probe.c |    6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -729,8 +729,10 @@ int __devinit pci_scan_bridge(struct pci
 
 	/* Check if setup is sensible at all */
 	if (!pass &&
-	    (primary != bus->number || secondary <= bus->number)) {
-		dev_dbg(&dev->dev, "bus configuration invalid, reconfiguring\n");
+	    (primary != bus->number || secondary <= bus->number ||
+	     secondary > subordinate)) {
+		dev_info(&dev->dev, "bridge configuration invalid ([bus %02x-%02x]), reconfiguring\n",
+			 secondary, subordinate);
 		broken = 1;
 	}