From 35dc67d7d922b2c9a1adb006c7a0f370eeb5c114 Mon Sep 17 00:00:00 2001 From: Davidlohr Bueso Date: Fri, 8 Sep 2017 16:14:42 -0700 Subject: [PATCH] rbtree: add some additional comments for rebalancing cases 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 Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- 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 * / \ / \ -- 2.20.1