+or:
+
+ struct key *request_key_async(const struct key_type *type,
+ const char *description,
+ const char *callout_info,
+ size_t callout_len);
+
+or:
+
+ struct key *request_key_async_with_auxdata(const struct key_type *type,
+ const char *description,
+ const char *callout_info,
+ size_t callout_len,
+ void *aux);
+