PCI: check if a bus is added when removing it

When removing a bus, 'is_added' should be checked to make sure the
bus has been successfully added by pci_bus_add_child() who will sets
'is_added'.

Signed-off-by: Yu Zhao <yu.zhao@intel.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>

drivers/pci/remove.c

@@ -71,6 +71,9 @@ void pci_remove_bus(struct pci_bus *pci_bus)
 	down_write(&pci_bus_sem);
 	list_del(&pci_bus->node);
 	up_write(&pci_bus_sem);
+	if (!pci_bus->is_added)
+		return;
+
 	pci_remove_legacy_files(pci_bus);
 	device_remove_file(&pci_bus->dev, &dev_attr_cpuaffinity);
 	device_remove_file(&pci_bus->dev, &dev_attr_cpulistaffinity);