Patchwork [v6,01/16] rbtree: remove redundant if()-condition in rb_erase()

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Submitter Praveen Kumar
Date Nov. 21, 2017, 3:19 p.m.
Message ID <20171121152009.15591-2-kpraveen.lkml@gmail.com>
Download mbox | patch
Permalink /patch/387535/
State New
Headers show

Comments

Praveen Kumar - Nov. 21, 2017, 3:19 p.m.
From: Wolfram Strepp <wstrepp@gmx.de>

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@gmx.de>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
[Linux commit 4b324126e0c6c3a5080ca3ec0981e8766ed6f1ee]

Ported to Xen.

Signed-off-by: Praveen Kumar <kpraveen.lkml@gmail.com>
---
Removed new line from previous patch to sync the changes completely with linux
code base.
---
 xen/common/rbtree.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

Patch

diff --git a/xen/common/rbtree.c b/xen/common/rbtree.c
index 167ebfdc4d..62e6387dcd 100644
--- a/xen/common/rbtree.c
+++ b/xen/common/rbtree.c
@@ -250,15 +250,15 @@  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;
 	}