- * Retry if there has been a concurrent add before us.
- * Retry if the prev node has been deleted.
- * There cannot be a concurrent delete for our position, because
- * we won the deletion flag cmpxchg.
- * If there is a concurrent add after us, our deletion flag
- * makes it busy-loop (FIXME: not lock-free).
+ * - Retry if there has been a concurrent add before us.
+ * - Retry if the prev node has been deleted (its next removed
+ * flag would be set).
+ * - There cannot be a concurrent delete for our position, because
+ * we won the deletion flag cmpxchg.
+ * - If there is a concurrent add or remove after us while our
+ * removed flag is set, it will skip us and link directly after
+ * the prior non-removed node before us. In this case, the
+ * retry will not find the node in the list anymore.