struct bus_type的drivers与klist_drivers有什么不同？

init  bus_register(struct bus_type *bus) ;

int bus_add_driver(struct device_driver * drv)
{
 struct bus_type * bus = get_bus(drv->bus);
 int error = 0;

 if (bus) {
  pr_debug("bus %s: add driver %s\n", bus->name, drv->name);
  error = kobject_set_name(&drv->kobj, "%s", drv->name);
  if (error) {
   put_bus(bus);
   return error;
  }
  drv->kobj.kset = &bus->drivers;
  if ((error = kobject_register(&drv->kobj))) {
   put_bus(bus);
   return error;
  }

  driver_attach(drv);

  /*把驱动加入链表klist_drivers ?*/
  klist_add_tail(&drv->knode_bus, &bus->klist_drivers);
  module_add_driver(drv->owner, drv);

  driver_add_attrs(bus, drv);
  driver_create_file(drv, &driver_attr_unbind);
  driver_create_file(drv, &driver_attr_bind);
 }
 return error;
}