From c0c82fb30e9331c5ea1055e94e4057d51a35d570 Mon Sep 17 00:00:00 2001
From: Davidlohr Bueso <dave@stgolabs.net>
Date: Wed, 2 Aug 2017 10:37:59 +1000
Subject: [PATCH 03/17] rbtree: add some additional comments for rebalancing cases
Git-commit: c0c82fb30e9331c5ea1055e94e4057d51a35d570
Patch-mainline: Queued in subsystem maintainer repository
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git
References: bsc#1052639
While overall the code is very nicely commented, it might not be
immediately obvious from the diagrams what is going on. Add a very brief
summary of each case. Opposite cases where the node is the left child are
left untouched.
Link: http://lkml.kernel.org/r/20170719014603.19029-4-dave@stgolabs.net
Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
---
lib/rbtree.c | 8 +++++---
1 file changed, 5 insertions(+), 3 deletions(-)
diff --git a/lib/rbtree.c b/lib/rbtree.c
index e7cce12f404f..ba4a9d165f1b 100644
--- a/lib/rbtree.c
+++ b/lib/rbtree.c
@@ -132,7 +132,7 @@ __rb_insert(struct rb_node *node, struct rb_root *root,
if (parent != tmp) { /* parent == gparent->rb_left */
if (tmp && rb_is_red(tmp)) {
/*
- * Case 1 - color flips
+ * Case 1 - node's uncle is red (color flips).
*
* G g
* / \ / \
@@ -155,7 +155,8 @@ __rb_insert(struct rb_node *node, struct rb_root *root,
tmp = parent->rb_right;
if (node == tmp) {
/*
- * Case 2 - left rotate at parent
+ * Case 2 - node's uncle is black and node is
+ * the parent's right child (left rotate at parent).
*
* G G
* / \ / \
@@ -179,7 +180,8 @@ __rb_insert(struct rb_node *node, struct rb_root *root,
}
/*
- * Case 3 - right rotate at gparent
+ * Case 3 - node's uncle is black and node is
+ * the parent's left child (right rotate at gparent).
*
* G P
* / \ / \
--
2.12.0