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.

Signed-off-by: Davidlohr Bueso <[email protected]>
---
 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

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