__key_link_lock
extern int __key_link_lock(struct key *keyring,
ret = __key_link_lock(keyring, &key->index_key);
link_ret = __key_link_lock(keyring, &key->index_key);
ret = __key_link_lock(keyring, &index_key);
ret = __key_link_lock(keyring, &key->index_key);
ret = __key_link_lock(dest_keyring, &key->index_key);