Re: [PATCH 6/6] rbtree: remove prior augmented rbtree implementation

[Michel Lespinasse <walken@google.com>]

convert arch/x86/mm/pat_rbtree.c to the proposed augmented rbtree api
and remove the old augmented rbtree implementation.

Signed-off-by: Michel Lespinasse <walken@google.com>
---
 arch/x86/mm/pat_rbtree.c |   63 ++++++++++++++++++++++++++++------------
 include/linux/rbtree.h   |    8 -----
 lib/rbtree.c             |   71 ----------------------------------------------
 lib/rbtree_test.c        |   11 ++-----
 4 files changed, 47 insertions(+), 106 deletions(-)

diff --git a/arch/x86/mm/pat_rbtree.c b/arch/x86/mm/pat_rbtree.c
index 8acaddd..5b8c8b2 100644
--- a/arch/x86/mm/pat_rbtree.c
+++ b/arch/x86/mm/pat_rbtree.c
@@ -13,6 +13,7 @@
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/rbtree.h>
+#include <linux/rbtree_internal.h>
 #include <linux/sched.h>
 #include <linux/gfp.h>
 
@@ -54,27 +55,51 @@ static u64 get_subtree_max_end(struct rb_node *node)
 	return ret;
 }
 
-/* Update 'subtree_max_end' for a node, based on node and its children */
-static void memtype_rb_augment_cb(struct rb_node *node, void *__unused)
+static u64 compute_subtree_max_end(struct memtype *data)
 {
-	struct memtype *data;
-	u64 max_end, child_max_end;
-
-	if (!node)
-		return;
-
-	data = container_of(node, struct memtype, rb);
-	max_end = data->end;
+	u64 max_end = data->end, child_max_end;
 
-	child_max_end = get_subtree_max_end(node->rb_right);
+	child_max_end = get_subtree_max_end(data->rb.rb_right);
 	if (child_max_end > max_end)
 		max_end = child_max_end;
 
-	child_max_end = get_subtree_max_end(node->rb_left);
+	child_max_end = get_subtree_max_end(data->rb.rb_left);
 	if (child_max_end > max_end)
 		max_end = child_max_end;
 
-	data->subtree_max_end = max_end;
+	return max_end;
+}
+
+/* Update 'subtree_max_end' after tree rotation. old and new are the
+ * former and current subtree roots */
+static void memtype_rb_rotate_cb(struct rb_node *old, struct rb_node *new)
+{
+	struct memtype *old_data = container_of(old, struct memtype, rb);
+	struct memtype *new_data = container_of(new, struct memtype, rb);
+
+	new_data->subtree_max_end = old_data->subtree_max_end;
+	old_data->subtree_max_end = compute_subtree_max_end(old_data);
+}
+
+static void memtype_rb_copy_cb(struct rb_node *old, struct rb_node *new)
+{
+	struct memtype *old_data = container_of(old, struct memtype, rb);
+	struct memtype *new_data = container_of(new, struct memtype, rb);
+
+	new_data->subtree_max_end = old_data->subtree_max_end;
+}
+
+/* Update 'subtree_max_end' for node and its parents */
+static void memtype_rb_propagate_cb(struct rb_node *node, struct rb_node *stop)
+{
+	while (node != stop) {
+		struct memtype *data = container_of(node, struct memtype, rb);
+		u64 subtree_max_end = compute_subtree_max_end(data);
+		if (data->subtree_max_end == subtree_max_end)
+			break;
+		data->subtree_max_end = subtree_max_end;
+		node = rb_parent(&data->rb);
+	}
 }
 
 /* Find the first (lowest start addr) overlapping range from rb tree */
@@ -179,15 +204,17 @@ static void memtype_rb_insert(struct rb_root *root, struct memtype *newdata)
 		struct memtype *data = container_of(*node, struct memtype, rb);
 
 		parent = *node;
+		if (data->subtree_max_end < newdata->end)
+			data->subtree_max_end = newdata->end;
 		if (newdata->start <= data->start)
 			node = &((*node)->rb_left);
 		else if (newdata->start > data->start)
 			node = &((*node)->rb_right);
 	}
 
+	newdata->subtree_max_end = newdata->end;
 	rb_link_node(&newdata->rb, parent, node);
-	rb_insert_color(&newdata->rb, root);
-	rb_augment_insert(&newdata->rb, memtype_rb_augment_cb, NULL);
+	rb_insert_augmented(&newdata->rb, root, memtype_rb_rotate_cb);
 }
 
 int rbt_memtype_check_insert(struct memtype *new, unsigned long *ret_type)
@@ -209,16 +236,14 @@ int rbt_memtype_check_insert(struct memtype *new, unsigned long *ret_type)
 
 struct memtype *rbt_memtype_erase(u64 start, u64 end)
 {
-	struct rb_node *deepest;
 	struct memtype *data;
 
 	data = memtype_rb_exact_match(&memtype_rbroot, start, end);
 	if (!data)
 		goto out;
 
-	deepest = rb_augment_erase_begin(&data->rb);
-	rb_erase(&data->rb, &memtype_rbroot);
-	rb_augment_erase_end(deepest, memtype_rb_augment_cb, NULL);
+	rb_erase_augmented(&data->rb, &memtype_rbroot, memtype_rb_copy_cb,
+			   memtype_rb_propagate_cb, memtype_rb_rotate_cb);
 out:
 	return data;
 }
diff --git a/include/linux/rbtree.h b/include/linux/rbtree.h
index bf836a2..487f00b 100644
--- a/include/linux/rbtree.h
+++ b/include/linux/rbtree.h
@@ -61,14 +61,6 @@ struct rb_root {
 extern void rb_insert_color(struct rb_node *, struct rb_root *);
 extern void rb_erase(struct rb_node *, struct rb_root *);
 
-typedef void (*rb_augment_f)(struct rb_node *node, void *data);
-
-extern void rb_augment_insert(struct rb_node *node,
-			      rb_augment_f func, void *data);
-extern struct rb_node *rb_augment_erase_begin(struct rb_node *node);
-extern void rb_augment_erase_end(struct rb_node *node,
-				 rb_augment_f func, void *data);
-
 /* 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 *);
diff --git a/lib/rbtree.c b/lib/rbtree.c
index 90349ec..62080ce 100644
--- a/lib/rbtree.c
+++ b/lib/rbtree.c
@@ -366,77 +366,6 @@ void rb_erase(struct rb_node *node, struct rb_root *root)
 }
 EXPORT_SYMBOL(rb_erase);
 
-static void rb_augment_path(struct rb_node *node, rb_augment_f func, void *data)
-{
-	struct rb_node *parent;
-
-up:
-	func(node, data);
-	parent = rb_parent(node);
-	if (!parent)
-		return;
-
-	if (node == parent->rb_left && parent->rb_right)
-		func(parent->rb_right, data);
-	else if (parent->rb_left)
-		func(parent->rb_left, data);
-
-	node = parent;
-	goto up;
-}
-
-/*
- * after inserting @node into the tree, update the tree to account for
- * both the new entry and any damage done by rebalance
- */
-void rb_augment_insert(struct rb_node *node, rb_augment_f func, void *data)
-{
-	if (node->rb_left)
-		node = node->rb_left;
-	else if (node->rb_right)
-		node = node->rb_right;
-
-	rb_augment_path(node, func, data);
-}
-EXPORT_SYMBOL(rb_augment_insert);
-
-/*
- * before removing the node, find the deepest node on the rebalance path
- * that will still be there after @node gets removed
- */
-struct rb_node *rb_augment_erase_begin(struct rb_node *node)
-{
-	struct rb_node *deepest;
-
-	if (!node->rb_right && !node->rb_left)
-		deepest = rb_parent(node);
-	else if (!node->rb_right)
-		deepest = node->rb_left;
-	else if (!node->rb_left)
-		deepest = node->rb_right;
-	else {
-		deepest = rb_next(node);
-		if (deepest->rb_right)
-			deepest = deepest->rb_right;
-		else if (rb_parent(deepest) != node)
-			deepest = rb_parent(deepest);
-	}
-
-	return deepest;
-}
-EXPORT_SYMBOL(rb_augment_erase_begin);
-
-/*
- * after removal, update the tree to account for the removed entry
- * and any rebalance damage.
- */
-void rb_augment_erase_end(struct rb_node *node, rb_augment_f func, void *data)
-{
-	if (node)
-		rb_augment_path(node, func, data);
-}
-EXPORT_SYMBOL(rb_augment_erase_end);
-
 /*
  * This function returns the first node (in sort order) of the tree.
  */
diff --git a/lib/rbtree_test.c b/lib/rbtree_test.c
index 278dbfc..140e173 100644
--- a/lib/rbtree_test.c
+++ b/lib/rbtree_test.c
@@ -129,16 +129,11 @@ static void init(void)
 	}
 }
 
-static bool is_red(struct rb_node *rb)
-{
-	return !(rb->__rb_parent_color & 1);
-}
-
 static int black_path_count(struct rb_node *rb)
 {
 	int count;
 	for (count = 0; rb; rb = rb_parent(rb))
-		count += !is_red(rb);
+		count += rb_is_black(rb);
 	return count;
 }
 
@@ -152,8 +147,8 @@ static void check(int nr_nodes)
 	for (rb = rb_first(&root); rb; rb = rb_next(rb)) {
 		struct test_node *node = rb_entry(rb, struct test_node, rb);
 		WARN_ON_ONCE(node->key < prev_key);
-		WARN_ON_ONCE(is_red(rb) &&
-			     (!rb_parent(rb) || is_red(rb_parent(rb))));
+		WARN_ON_ONCE(rb_is_red(rb) &&
+			     (!rb_parent(rb) || rb_is_red(rb_parent(rb))));
 		if (!count)
 			blacks = black_path_count(rb);
 		else
-- 
1.7.7.3

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