diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index 6e34498ec9f0..509494381a7a 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -731,22 +731,6 @@ struct pci_bus *__ref pci_add_new_bus(struct pci_bus *parent, struct pci_dev *de
 	return child;
 }
 
-static void pci_fixup_parent_subordinate_busnr(struct pci_bus *child, int max)
-{
-	struct pci_bus *parent = child->parent;
-
-	/* Attempts to fix that up are really dangerous unless
-	   we're going to re-assign all bus numbers. */
-	if (!pcibios_assign_all_busses())
-		return;
-
-	while (parent->parent && parent->busn_res.end < max) {
-		parent->busn_res.end = max;
-		pci_write_config_byte(parent->self, PCI_SUBORDINATE_BUS, max);
-		parent = parent->parent;
-	}
-}
-
 /*
  * If it's a bridge, configure it and scan the bus behind it.
  * For CardBus bridges, we don't scan behind as the devices will
@@ -782,7 +766,7 @@ int pci_scan_bridge(struct pci_bus *bus, struct pci_dev *dev, int max, int pass)
 	/* Check if setup is sensible at all */
 	if (!pass &&
 	    (primary != bus->number || secondary <= bus->number ||
-	     secondary > subordinate)) {
+	     secondary > subordinate || subordinate > bus->busn_res.end)) {
 		dev_info(&dev->dev, "bridge configuration invalid ([bus %02x-%02x]), reconfiguring\n",
 			 secondary, subordinate);
 		broken = 1;
@@ -805,11 +789,10 @@ int pci_scan_bridge(struct pci_bus *bus, struct pci_dev *dev, int max, int pass)
 			goto out;
 
 		/*
-		 * If we already got to this bus through a different bridge,
-		 * don't re-add it. This can happen with the i450NX chipset.
-		 *
-		 * However, we continue to descend down the hierarchy and
-		 * scan remaining child buses.
+		 * The bus might already exist for two reasons: Either we are
+		 * rescanning the bus or the bus is reachable through more than
+		 * one bridge. The second case can happen with the i450NX
+		 * chipset.
 		 */
 		child = pci_find_bus(pci_domain_nr(bus), secondary);
 		if (!child) {
@@ -822,17 +805,19 @@ int pci_scan_bridge(struct pci_bus *bus, struct pci_dev *dev, int max, int pass)
 		}
 
 		cmax = pci_scan_child_bus(child);
-		if (cmax > max)
-			max = cmax;
-		if (child->busn_res.end > max)
-			max = child->busn_res.end;
+		if (cmax > subordinate)
+			dev_warn(&dev->dev, "bridge has subordinate %02x but max busn %02x\n",
+				 subordinate, cmax);
+		/* subordinate should equal child->busn_res.end */
+		if (subordinate > max)
+			max = subordinate;
 	} else {
 		/*
 		 * We need to assign a number to this bus which we always
 		 * do in the second pass.
 		 */
 		if (!pass) {
-			if (pcibios_assign_all_busses() || broken)
+			if (pcibios_assign_all_busses() || broken || is_cardbus)
 				/* Temporarily disable forwarding of the
 				   configuration cycles on all bridges in
 				   this bus segment to avoid possible
@@ -844,19 +829,25 @@ int pci_scan_bridge(struct pci_bus *bus, struct pci_dev *dev, int max, int pass)
 			goto out;
 		}
 
+		if (max >= bus->busn_res.end) {
+			dev_warn(&dev->dev, "can't allocate child bus %02x from %pR\n",
+				 max, &bus->busn_res);
+			goto out;
+		}
+
 		/* Clear errors */
 		pci_write_config_word(dev, PCI_STATUS, 0xffff);
 
-		/* Prevent assigning a bus number that already exists.
-		 * This can happen when a bridge is hot-plugged, so in
-		 * this case we only re-scan this bus. */
+		/* The bus will already exist if we are rescanning */
 		child = pci_find_bus(pci_domain_nr(bus), max+1);
 		if (!child) {
-			child = pci_add_new_bus(bus, dev, ++max);
+			child = pci_add_new_bus(bus, dev, max+1);
 			if (!child)
 				goto out;
-			pci_bus_insert_busn_res(child, max, 0xff);
+			pci_bus_insert_busn_res(child, max+1,
+						bus->busn_res.end);
 		}
+		max++;
 		buses = (buses & 0xff000000)
 		      | ((unsigned int)(child->primary)     <<  0)
 		      | ((unsigned int)(child->busn_res.start)   <<  8)
@@ -878,20 +869,7 @@ int pci_scan_bridge(struct pci_bus *bus, struct pci_dev *dev, int max, int pass)
 
 		if (!is_cardbus) {
 			child->bridge_ctl = bctl;
-			/*
-			 * Adjust subordinate busnr in parent buses.
-			 * We do this before scanning for children because
-			 * some devices may not be detected if the bios
-			 * was lazy.
-			 */
-			pci_fixup_parent_subordinate_busnr(child, max);
-			/* Now we can scan all subordinate buses... */
 			max = pci_scan_child_bus(child);
-			/*
-			 * now fix it up again since we have found
-			 * the real value of max.
-			 */
-			pci_fixup_parent_subordinate_busnr(child, max);
 		} else {
 			/*
 			 * For CardBus bridges, we leave 4 bus numbers
@@ -922,11 +900,15 @@ int pci_scan_bridge(struct pci_bus *bus, struct pci_dev *dev, int max, int pass)
 				}
 			}
 			max += i;
-			pci_fixup_parent_subordinate_busnr(child, max);
 		}
 		/*
 		 * Set the subordinate bus number to its real value.
 		 */
+		if (max > bus->busn_res.end) {
+			dev_warn(&dev->dev, "max busn %02x is outside %pR\n",
+				 max, &bus->busn_res);
+			max = bus->busn_res.end;
+		}
 		pci_bus_update_busn_res_end(child, max);
 		pci_write_config_byte(dev, PCI_SUBORDINATE_BUS, max);
 	}
@@ -1835,7 +1817,7 @@ int pci_bus_insert_busn_res(struct pci_bus *b, int bus, int bus_max)
 		res->flags |= IORESOURCE_PCI_FIXED;
 	}
 
-	conflict = insert_resource_conflict(parent_res, res);
+	conflict = request_resource_conflict(parent_res, res);
 
 	if (conflict)
 		dev_printk(KERN_DEBUG, &b->dev,