A possible improper locking bug

int sigwait(sigset_t *setp, int *sigp)

{

  ...;

  pthread_mutex_lock(&LOCK_sigwait);

  for (;;)

  {

    ...;

	pthread_mutex_unlock(&LOCK_sigwait); // release the lock before return

	return 0;

      }

    }

    pthread_cond_wait(&COND_sigwait, &LOCK_sigwait);

  }

  return 0; // do not release the lock before return

}