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From: Praveen Kumar <kpraveen.lkml@gmail.com>
To: xen-devel@lists.xen.org
Cc: sstabellini@kernel.org, wei.liu2@citrix.com,
	Peter Zijlstra <a.p.zijlstra@chello.nl>,
	George.Dunlap@eu.citrix.com, andrew.cooper3@citrix.com,
	dario.faggioli@citrix.com, ian.jackson@eu.citrix.com,
	tim@xen.org, Praveen Kumar <kpraveen.lkml@gmail.com>,
	jbeulich@suse.com, Andrew Morton <akpm@linux-foundation.org>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Wolfram Strepp <wstrepp@gmx.de>
Subject: [PATCH 03/17] rb_tree: remove redundant if()-condition in rb_erase()
Date: Thu,  1 Jun 2017 02:16:54 +0530	[thread overview]
Message-ID: <20170531204708.10470-4-kpraveen.lkml@gmail.com> (raw)
In-Reply-To: <20170531204708.10470-1-kpraveen.lkml@gmail.com>

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.

commit 4b324126e0c6c3a5080ca3ec0981e8766ed6f1ee from linux tree

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>
---
 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 3df599c3cb..0695edd9f9 100644
--- a/xen/common/rbtree.c
+++ b/xen/common/rbtree.c
@@ -256,15 +256,16 @@ 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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  parent reply	other threads:[~2017-05-31 20:46 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-05-31 20:46 [PATCH v2] xen: common: rbtree: ported updates from linux tree Praveen Kumar
2017-05-31 20:46 ` [PATCH 01/17] rb_tree: reorganize code in rb_erase() for additional changes Praveen Kumar
2017-05-31 20:46 ` [PATCH 02/17] rb_tree: make clear distinction between two different cases in rb_erase() Praveen Kumar
2017-05-31 20:46 ` Praveen Kumar [this message]
2017-05-31 20:46 ` [PATCH 04/17] rbtree: empty nodes have no color Praveen Kumar
2017-05-31 20:46 ` [PATCH 05/17] rbtree: move some implementation details from rbtree.h to rbtree.c Praveen Kumar
2017-05-31 20:46 ` [PATCH 06/17] rbtree: break out of rb_insert_color loop after tree rotation Praveen Kumar
2017-05-31 20:46 ` [PATCH 07/17] rbtree: adjust root color in rb_insert_color() only when necessary Praveen Kumar
2017-05-31 20:46 ` [PATCH 08/17] rbtree: low level optimizations in rb_insert_color() Praveen Kumar
2017-05-31 20:47 ` [PATCH 09/17] rbtree: adjust node color in __rb_erase_color() only when necessary Praveen Kumar
2017-05-31 20:47 ` [PATCH 10/17] rbtree: optimize case selection logic in __rb_erase_color() Praveen Kumar
2017-05-31 20:47 ` [PATCH 11/17] rbtree: low level optimizations " Praveen Kumar
2017-05-31 20:47 ` [PATCH 12/17] rbtree: optimize fetching of sibling node Praveen Kumar
2017-05-31 20:47 ` [PATCH 13/17] rbtree: add __rb_change_child() helper function Praveen Kumar
2017-05-31 20:47 ` [PATCH 14/17] rbtree: place easiest case first in rb_erase() Praveen Kumar
2017-05-31 20:47 ` [PATCH 15/17] rbtree: handle 1-child recoloring in rb_erase() instead of rb_erase_color() Praveen Kumar
2017-05-31 21:09   ` Praveen Kumar

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