+static DEFINE_MUTEX(mdesc_mutex);
+static struct mdesc_notifier_client *client_list;
+
+void mdesc_register_notifier(struct mdesc_notifier_client *client)
+{
+ u64 node;
+
+ mutex_lock(&mdesc_mutex);
+ client->next = client_list;
+ client_list = client;
+
+ mdesc_for_each_node_by_name(cur_mdesc, node, client->node_name)
+ client->add(cur_mdesc, node);
+
+ mutex_unlock(&mdesc_mutex);
+}
+
+/* Run 'func' on nodes which are in A but not in B. */
+static void invoke_on_missing(const char *name,
+ struct mdesc_handle *a,
+ struct mdesc_handle *b,
+ void (*func)(struct mdesc_handle *, u64))
+{
+ u64 node;
+
+ mdesc_for_each_node_by_name(a, node, name) {
+ const u64 *id = mdesc_get_property(a, node, "id", NULL);
+ int found = 0;
+ u64 fnode;
+
+ mdesc_for_each_node_by_name(b, fnode, name) {
+ const u64 *fid = mdesc_get_property(b, fnode,
+ "id", NULL);
+
+ if (*id == *fid) {
+ found = 1;
+ break;
+ }
+ }
+ if (!found)
+ func(a, node);
+ }
+}
+
+static void notify_one(struct mdesc_notifier_client *p,
+ struct mdesc_handle *old_hp,
+ struct mdesc_handle *new_hp)
+{
+ invoke_on_missing(p->node_name, old_hp, new_hp, p->remove);
+ invoke_on_missing(p->node_name, new_hp, old_hp, p->add);
+}
+
+static void mdesc_notify_clients(struct mdesc_handle *old_hp,
+ struct mdesc_handle *new_hp)
+{
+ struct mdesc_notifier_client *p = client_list;
+
+ while (p) {
+ notify_one(p, old_hp, new_hp);
+ p = p->next;
+ }
+}
+