rcuja: document destroy requirement

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

diff --git a/urcu/rcuja.h b/urcu/rcuja.h
index f8cba6af4da08fb5ba0aa7a0a1d46d8c3f16e377..4570f1a89da4512184d8fd785a314934ad0d4075 100644 (file)
--- a/urcu/rcuja.h
+++ b/urcu/rcuja.h
@@ -58,30 +58,99 @@ void cds_ja_node_init(struct cds_ja_node *node)
 {
 }
 
+/*
+ * cds_ja_lookup - look up by key.
+ * @ja: the Judy array.
+ * @key: key to look up.
+ *
+ * Returns the first node of a duplicate chain if a match is found, 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(struct cds_ja *ja, uint64_t key);
+
+/*
+ * cds_ja_lookup_lower_equal - look up first node with key <= @key.
+ * @ja: the Judy array.
+ * @key: key to look up.
+ *
+ * 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.
+ * 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);
 
+/*
+ * cds_ja_add - Add @node at @key, allowing duplicates.
+ * @ja: the Judy array.
+ * @key: key at which @node should be added.
+ * @node: node to add.
+ *
+ * Returns 0 on success, negative error value on error.
+ * A RCU read-side lock should be held across call to this function.
+ */
 int cds_ja_add(struct cds_ja *ja, uint64_t key,
-               struct cds_ja_node *new_node);
+               struct cds_ja_node *node);
 
+/*
+ * cds_ja_add_unique - Add @node at @key, without duplicates.
+ * @ja: the Judy array.
+ * @key: key at which @node should be added.
+ * @node: node to add.
+ *
+ * Returns @node if successfully added, else returns the already
+ * existing node (acts as a RCU lookup).
+ * 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_add_unique(struct cds_ja *ja, uint64_t key,
-               struct cds_ja_node *new_node);
+               struct cds_ja_node *node);
 
+/*
+ * cds_ja_del - Remove @node at @key.
+ * @ja: the Judy array.
+ * @key: key at which @node is expected.
+ * @node: node to remove.
+ *
+ * Returns 0 on success, negative error value on error.
+ * A RCU read-side lock should be held across call to this function.
+ */
 int cds_ja_del(struct cds_ja *ja, uint64_t key,
                struct cds_ja_node *node);
 
 struct cds_ja *_cds_ja_new(unsigned int key_bits,
                const struct rcu_flavor_struct *flavor);
 
+/*
+ * cds_ja_new - Create a Judy array.
+ * @key_bits: Number of bits for key.
+ *
+ * Returns non-NULL pointer on success, else NULL on error. @key_bits
+ * needs to be multiple of 8, either: 8, 16, 24, 32, 40, 48, 56, or 64.
+ */
 static inline
 struct cds_ja *cds_ja_new(unsigned int key_bits)
 {
        return _cds_ja_new(key_bits, &rcu_flavor);
 }
 
+/*
+ * cds_ja_destroy - Destroy a Judy array.
+ * @ja: the Judy array.
+ * @rcu_free_node_cb: callback performing memory free of leftover nodes.
+ *
+ * Returns 0 on success, negative error value on error.
+ * 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.
+ */
 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*()