for (i=0; i<MAX_NUMBER_OF_NONCES; i++) {
      if (rwl_readtrylock(&nonces[i].lock))
        continue;
      if ((current_time-nonces[i].created) >= 300) {
        /* Old nonce - remove it */
        rwl_swaplock(&nonces[i].lock, RWLOCK_WRITE);
        nonces[i].state = NOT_USED;
        rwl_writeunlock(&nonces[i].lock);
      } else {
        rwl_readunlock(&nonces[i].lock);
      }
    }