Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 35dc67d7 authored by Davidlohr Bueso's avatar Davidlohr Bueso Committed by Linus Torvalds
Browse files

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: default avatarDavidlohr Bueso <dbueso@suse.de>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 2aadf7fc

lib/rbtree.c

+5 −3
Original line number Diff line number Diff line
@@ -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

			 *       / \         / \