Page History

...

    // "take" a node with marking:
    while (true) {
      cur = head;
      if (!mark_next(cur, &next)) {
        // could not mark cur so try again
        continue;
      }
      if (head != cur) {
        // head changed while marking cur so try again
        unmark_next(cur);
        continue;
      }
      // list head is now marked so switch it to next which also makes list head unmarked
      AtomicOrderAccess::release_store(&head, next);
      unmark_next(cur);  // unmark cur and return it
      return cur;
    }

...