Comment 2 for bug 715066

Actually:

/**
 * This is the common functionality used to put a password generated key into
 * the keyring, shared by both non-interactive and interactive signature
 * generation code.
 *
 * Returns 0 on add, 1 on pre-existed, negative on failure.
 */
int ecryptfs_add_passphrase_key_to_keyring(char *auth_tok_sig, char *passphrase,
                                           char *salt)
{
...

So I think we just need to test the return code for <0.