BUG_ON(!dn->phb || !dn->phb->bus); 
if (!dn->phb || !dn->phb->bus) return NULL; 
struct pci_bus *rpaphp_find_pci_bus(struct device_node *dn){	BUG_ON(!dn->phb || !dn->phb->bus);	return find_bus_among_children(dn->phb->bus, dn);}
4520	/local/tlutelli/issta_data/temp/c/2005_temp/2005/4520/0945cd5f908a09ad99bf42d7ded16f26f24f317d/rpaphp_pci.c/buggy/drivers/pci/hotplug/rpaphp_pci.c