rculfhash: fix uniquely add vs cds_lfht_next observation semantic

[urcu.git] / rculfhash.c

diff --git a/rculfhash.c b/rculfhash.c
index 18a3cb89c8b273b81757fd763f4b472d8301e6d6..b67acc820a078011f81963608f7c366fc1a3d2ec 100644 (file)
--- a/rculfhash.c
+++ b/rculfhash.c
@@ -894,22 +894,38 @@ void _cds_lfht_add(struct cds_lfht *ht,
                                goto insert;
                        if (likely(clear_flag(iter)->p.reverse_hash > node->p.reverse_hash))
                                goto insert;
+
                        /* dummy node is the first node of the identical-hash-value chain */
                        if (dummy && clear_flag(iter)->p.reverse_hash == node->p.reverse_hash)
                                goto insert;
+
                        next = rcu_dereference(clear_flag(iter)->p.next);
                        if (unlikely(is_removed(next)))
                                goto gc_node;
+
+                       /* uniquely add */
                        if (unique_ret
                            && !is_dummy(next)
-                           && clear_flag(iter)->p.reverse_hash == node->p.reverse_hash
-                           && !ht->compare_fct(node->key, node->key_len,
-                                               clear_flag(iter)->key,
-                                               clear_flag(iter)->key_len)) {
-                               unique_ret->node = clear_flag(iter);
-                               unique_ret->next = next;
+                           && clear_flag(iter)->p.reverse_hash == node->p.reverse_hash) {
+                               struct cds_lfht_iter d_iter = { .node = node, .next = iter, };
+
+                               /*
+                                * uniquely adding inserts the node as the first
+                                * node of the identical-hash-value node chain.
+                                *
+                                * This semantic ensures no duplicated keys
+                                * should ever be observable in the table
+                                * (including observe one node by one node
+                                * by forward iterations)
+                                */
+                               cds_lfht_next_duplicate(ht, &d_iter);
+                               if (!d_iter.node)
+                                       goto insert;
+
+                               *unique_ret = d_iter;
                                return;
                        }
+
                        /* Only account for identical reverse hash once */
                        if (iter_prev->p.reverse_hash != clear_flag(iter)->p.reverse_hash
                            && !is_dummy(next))