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

[Praveen Kumar <kpraveen.lkml@xxxxxxxxx>]

From: Wolfram Strepp <wstrepp@xxxxxx>

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 <wstrepp@xxxxxx>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
[Linux commit 4b324126e0c6c3a5080ca3ec0981e8766ed6f1ee]

Ported to Xen.

Signed-off-by: Praveen Kumar <kpraveen.lkml@xxxxxxxxx>
---
 xen/common/rbtree.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

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;
        }
 
-- 
2.12.0


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