[v4,02/17] rbtree: remove redundant if()-condition in rb_erase()

Commit Message

Praveen Kumar July 3, 2017, 7:58 p.m. UTC

From: Wolfram Strepp <[e-mail]>

Furthermore, notice that the initial checks:

            if (!node->rb_left)
                    child = node->rb_right;
            else if (!node->rb_right)
                    child = node->rb_left;
            else
            {
                    ...
            }
guarantee that old->rb_right is set in the final else branch, therefore
we can omit checking that again.

Signed-off-by: Wolfram Strepp <[e-mail]>
Signed-off-by: Peter Zijlstra <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>
[Linux commit 4b324126e0c6c3a5080ca3ec0981e8766ed6f1ee]

Ported to Xen.

Signed-off-by: Praveen Kumar <[e-mail]>
---
 xen/common/rbtree.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

Patch

diff --git a/xen/common/rbtree.c b/xen/common/rbtree.c
index d5e3d06b80..3a19b44a2f 100644
--- a/xen/common/rbtree.c
+++ b/xen/common/rbtree.c
@@ -249,15 +249,16 @@  void rb_erase(struct rb_node *node, struct rb_root *root)
 			if (child)
 				rb_set_parent(child, parent);
 			parent->rb_left = child;
+
+			node->rb_right = old->rb_right;
+			rb_set_parent(old->rb_right, node);
 		}
 
 		node->rb_parent_color = old->rb_parent_color;
-		node->rb_right = old->rb_right;
 		node->rb_left = old->rb_left;
 
 		rb_set_parent(old->rb_left, node);
-		if (old->rb_right)
-			rb_set_parent(old->rb_right, node);
+
 		goto color;
 	}