Index: drivers/pci/probe.c
===================================================================
--- drivers/pci/probe.c	(revision 102)
+++ drivers/pci/probe.c	(revision 103)
@@ -996,11 +996,21 @@
 struct pci_dev *__ref pci_scan_single_device(struct pci_bus *bus, int devfn)
 {
 	struct pci_dev *dev;
+	struct list_head *ln;
 
 	dev = pci_scan_device(bus, devfn);
 	if (!dev)
 		return NULL;
 
+	/* refuse to re-add a device */
+	list_for_each(ln, &bus->devices) {
+		struct pci_dev *d = pci_dev_b(ln);
+		if ((d->vendor == dev->vendor) &&
+		    (d->device == dev->device) &&
+		    (d->devfn == dev->devfn))
+			return NULL;
+	}
+
 	pci_device_add(dev, bus);
 
 	return dev;