rcuja: below/equal result key

[userspace-rcu.git] / urcu / rcuja.h

diff --git a/urcu/rcuja.h b/urcu/rcuja.h
index 2a0de286256b46bb12dabe07d95c85151ed16ccf..eb384941d6a7cde6d38c530a24702a505873ec9e 100644 (file)
--- a/urcu/rcuja.h
+++ b/urcu/rcuja.h
@@ -71,17 +71,32 @@ void cds_ja_node_init(struct cds_ja_node *node)
 struct cds_ja_node *cds_ja_lookup(struct cds_ja *ja, uint64_t key);
 
 /*
- * cds_ja_lookup_lower_equal - look up first node with key <= @key.
+ * cds_ja_lookup_below_equal - look up first node with key <= @key.
  * @ja: the Judy array.
  * @key: key to look up.
+ * @result_key: key found.
  *
  * Returns the first node of a duplicate chain if a node is present in
- * the tree which has a key lower or equal to @key, else returns NULL.
+ * the tree which has a key below or equal to @key, else returns NULL.
  * A RCU read-side lock should be held across call to this function and
  * use of its return value.
  */
-struct cds_ja_node *cds_ja_lookup_lower_equal(struct cds_ja *ja,
-               uint64_t key);
+struct cds_ja_node *cds_ja_lookup_below_equal(struct cds_ja *ja,
+               uint64_t key, uint64_t *result_key);
+
+/*
+ * cds_ja_lookup_above_equal - look up first node with key >= @key.
+ * @ja: the Judy array.
+ * @key: key to look up.
+ * @result_key: key found.
+ *
+ * Returns the first node of a duplicate chain if a node is present in
+ * the tree which has a key above or equal to @key, else returns NULL.
+ * A RCU read-side lock should be held across call to this function and
+ * use of its return value.
+ */
+struct cds_ja_node *cds_ja_lookup_above_equal(struct cds_ja *ja,
+               uint64_t key, uint64_t *result_key);
 
 /*
  * cds_ja_add - Add @node at @key, allowing duplicates.
@@ -143,11 +158,15 @@ struct cds_ja *cds_ja_new(unsigned int key_bits)
  * @rcu_free_node_cb: callback performing memory free of leftover nodes.
  *
  * Returns 0 on success, negative error value on error.
- * The @rcu_free_node_cb callback should internally wait for a grace
- * period before freeing the node.
+ * There should be no more concurrent add, delete, nor look-up performed
+ * on the Judy array while it is being destroyed (ensured by the caller).
+ * There is no need for the @rcu_free_node_cb callback to wait for grace
+ * periods, since there are no more concurrent users of the Judy array.
+ * RCU read-side lock should _not_ be held when calling this function,
+ * however, QSBR threads need to be online.
  */
 int cds_ja_destroy(struct cds_ja *ja,
-               void (*rcu_free_node_cb)(struct cds_ja_node *node));
+               void (*free_node_cb)(struct cds_ja_node *node));
 
 /*
  * Iterate through duplicates returned by cds_ja_lookup*()