Driver core: add missing kset uevent

We get uevents for a bus/class going away, but not one registering.
Add the missing uevent in kset_register(), which will send an
event for a new bus/class. Suppress all unwanted uevents for bus
subdirectories like /bus/*/devices/, /bus/*/drivers/.

Now we get for module usbcore:
  add      /module/usbcore (module)
  add      /bus/usb (bus)
  add      /class/usb_host (class)
  add      /bus/usb/drivers/hub (drivers)
  add      /bus/usb/drivers/usb (drivers)
  remove   /bus/usb/drivers/usb (drivers)
  remove   /bus/usb/drivers/hub (drivers)
  remove   /class/usb_host (class)
  remove   /bus/usb (bus)
  remove   /module/usbcore (module)

instead of:
  add      /module/usbcore (module)
  add      /bus/usb/drivers/hub (drivers)
  add      /bus/usb/drivers/usb (drivers)
  remove   /bus/usb/drivers/usb (drivers)
  remove   /bus/usb/drivers/hub (drivers)
  remove   /class/usb_host (class)
  remove   /bus/usb/drivers (bus)
  remove   /bus/usb/devices (bus)
  remove   /bus/usb (bus)
  remove   /module/usbcore (module)
Signed-off-by: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/base/bus.c

@@ -138,12 +138,24 @@ void bus_remove_file(struct bus_type * bus, struct bus_attribute * attr)
 	}
 }
 
-static struct kobj_type ktype_bus = {
+static struct kobj_type bus_ktype = {
 	.sysfs_ops	= &bus_sysfs_ops,
+};
+
+static int bus_uevent_filter(struct kset *kset, struct kobject *kobj)
+{
+	struct kobj_type *ktype = get_ktype(kobj);
+
+	if (ktype == &bus_ktype)
+		return 1;
+	return 0;
+}
 
+static struct kset_uevent_ops bus_uevent_ops = {
+	.filter = bus_uevent_filter,
 };
 
-static decl_subsys(bus, &ktype_bus, NULL);
+static decl_subsys(bus, &bus_ktype, &bus_uevent_ops);
 
 
 #ifdef CONFIG_HOTPLUG

lib/kobject.c

@@ -597,10 +597,17 @@ int kset_add(struct kset * k)
 
 int kset_register(struct kset * k)
 {
+	int err;
+
 	if (!k)
 		return -EINVAL;
+
 	kset_init(k);
-	return kset_add(k);
+	err = kset_add(k);
+	if (err)
+		return err;
+	kobject_uevent(&k->kobj, KOBJ_ADD);
+	return 0;
 }