1 files changed, 134 insertions, 2 deletions

diff --git a/include/linux/rbtree.h b/include/linux/rbtree.h
index f7edca369eda..4091e978aef2 100644
--- a/include/linux/rbtree.h
+++ b/include/linux/rbtree.h
@@ -43,8 +43,36 @@ extern void rb_erase(struct rb_node *, struct rb_root *);
 /* Find logical next and previous nodes in a tree */
 extern struct rb_node *rb_next(const struct rb_node *);
 extern struct rb_node *rb_prev(const struct rb_node *);
-extern struct rb_node *rb_first(const struct rb_root *);
-extern struct rb_node *rb_last(const struct rb_root *);
+
+/*
+ * This function returns the first node (in sort order) of the tree.
+ */
+static inline struct rb_node *rb_first(const struct rb_root *root)
+{
+	struct rb_node	*n;
+
+	n = root->rb_node;
+	if (!n)
+		return NULL;
+	while (n->rb_left)
+		n = n->rb_left;
+	return n;
+}
+
+/*
+ * This function returns the last node (in sort order) of the tree.
+ */
+static inline struct rb_node *rb_last(const struct rb_root *root)
+{
+	struct rb_node	*n;
+
+	n = root->rb_node;
+	if (!n)
+		return NULL;
+	while (n->rb_right)
+		n = n->rb_right;
+	return n;
+}
 
 /* Postorder iteration - always visit the parent after its children */
 extern struct rb_node *rb_first_postorder(const struct rb_root *);
@@ -211,6 +239,43 @@ rb_add(struct rb_node *node, struct rb_root *tree,
 }
 
 /**
+ * rb_find_add_cached() - find equivalent @node in @tree, or add @node
+ * @node: node to look-for / insert
+ * @tree: tree to search / modify
+ * @cmp: operator defining the node order
+ *
+ * Returns the rb_node matching @node, or NULL when no match is found and @node
+ * is inserted.
+ */
+static __always_inline struct rb_node *
+rb_find_add_cached(struct rb_node *node, struct rb_root_cached *tree,
+	    int (*cmp)(const struct rb_node *new, const struct rb_node *exist))
+{
+	bool leftmost = true;
+	struct rb_node **link = &tree->rb_root.rb_node;
+	struct rb_node *parent = NULL;
+	int c;
+
+	while (*link) {
+		parent = *link;
+		c = cmp(node, parent);
+
+		if (c < 0) {
+			link = &parent->rb_left;
+		} else if (c > 0) {
+			link = &parent->rb_right;
+			leftmost = false;
+		} else {
+			return parent;
+		}
+	}
+
+	rb_link_node(node, parent, link);
+	rb_insert_color_cached(node, tree, leftmost);
+	return NULL;
+}
+
+/**
  * rb_find_add() - find equivalent @node in @tree, or add @node
  * @node: node to look-for / insert
  * @tree: tree to search / modify
@@ -245,6 +310,42 @@ rb_find_add(struct rb_node *node, struct rb_root *tree,
 }
 
 /**
+ * rb_find_add_rcu() - find equivalent @node in @tree, or add @node
+ * @node: node to look-for / insert
+ * @tree: tree to search / modify
+ * @cmp: operator defining the node order
+ *
+ * Adds a Store-Release for link_node.
+ *
+ * Returns the rb_node matching @node, or NULL when no match is found and @node
+ * is inserted.
+ */
+static __always_inline struct rb_node *
+rb_find_add_rcu(struct rb_node *node, struct rb_root *tree,
+		int (*cmp)(struct rb_node *, const struct rb_node *))
+{
+	struct rb_node **link = &tree->rb_node;
+	struct rb_node *parent = NULL;
+	int c;
+
+	while (*link) {
+		parent = *link;
+		c = cmp(node, parent);
+
+		if (c < 0)
+			link = &parent->rb_left;
+		else if (c > 0)
+			link = &parent->rb_right;
+		else
+			return parent;
+	}
+
+	rb_link_node_rcu(node, parent, link);
+	rb_insert_color(node, tree);
+	return NULL;
+}
+
+/**
  * rb_find() - find @key in tree @tree
  * @key: key to match
  * @tree: tree to search
@@ -273,6 +374,37 @@ rb_find(const void *key, const struct rb_root *tree,
 }
 
 /**
+ * rb_find_rcu() - find @key in tree @tree
+ * @key: key to match
+ * @tree: tree to search
+ * @cmp: operator defining the node order
+ *
+ * Notably, tree descent vs concurrent tree rotations is unsound and can result
+ * in false-negatives.
+ *
+ * Returns the rb_node matching @key or NULL.
+ */
+static __always_inline struct rb_node *
+rb_find_rcu(const void *key, const struct rb_root *tree,
+	    int (*cmp)(const void *key, const struct rb_node *))
+{
+	struct rb_node *node = tree->rb_node;
+
+	while (node) {
+		int c = cmp(key, node);
+
+		if (c < 0)
+			node = rcu_dereference_raw(node->rb_left);
+		else if (c > 0)
+			node = rcu_dereference_raw(node->rb_right);
+		else
+			return node;
+	}
+
+	return NULL;
+}
+
+/**
  * rb_find_first() - find the first @key in @tree
  * @key: key to match
  * @tree: tree to search