The patch titled
Subject: rbtree: place easiest case first in rb_erase()
has been removed from the -mm tree. Its filename was
rbtree-place-easiest-case-first-in-rb_erase.patch
This patch was dropped because it was merged into mainline or a subsystem tree
------------------------------------------------------
From: Michel Lespinasse <walken@xxxxxxxxxx>
Subject: rbtree: place easiest case first in rb_erase()
In rb_erase, move the easy case (node to erase has no more than
1 child) first. I feel the code reads easier that way.
Signed-off-by: Michel Lespinasse <walken@xxxxxxxxxx>
Reviewed-by: Rik van Riel <riel@xxxxxxxxxx>
Cc: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Cc: David Woodhouse <dwmw2@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
lib/rbtree.c | 35 ++++++++++++++++++-----------------
1 file changed, 18 insertions(+), 17 deletions(-)
diff -puN lib/rbtree.c~rbtree-place-easiest-case-first-in-rb_erase lib/rbtree.c
--- a/lib/rbtree.c~rbtree-place-easiest-case-first-in-rb_erase
+++ a/lib/rbtree.c
@@ -368,17 +368,28 @@ static void __rb_erase_color(struct rb_n
void rb_erase(struct rb_node *node, struct rb_root *root)
{
- struct rb_node *child, *parent;
+ struct rb_node *child = node->rb_right, *tmp = node->rb_left;
+ struct rb_node *parent;
int color;
- if (!node->rb_left)
- child = node->rb_right;
- else if (!node->rb_right)
- child = node->rb_left;
- else {
+ if (!tmp) {
+ case1:
+ /* Case 1: node to erase has no more than 1 child (easy!) */
+
+ parent = rb_parent(node);
+ color = rb_color(node);
+
+ if (child)
+ rb_set_parent(child, parent);
+ __rb_change_child(node, child, parent, root);
+ } else if (!child) {
+ /* Still case 1, but this time the child is node->rb_left */
+ child = tmp;
+ goto case1;
+ } else {
struct rb_node *old = node, *left;
- node = node->rb_right;
+ node = child;
while ((left = node->rb_left) != NULL)
node = left;
@@ -402,18 +413,8 @@ void rb_erase(struct rb_node *node, stru
node->__rb_parent_color = old->__rb_parent_color;
node->rb_left = old->rb_left;
rb_set_parent(old->rb_left, node);
-
- goto color;
}
- parent = rb_parent(node);
- color = rb_color(node);
-
- if (child)
- rb_set_parent(child, parent);
- __rb_change_child(node, child, parent, root);
-
-color:
if (color == RB_BLACK)
__rb_erase_color(child, parent, root);
}
_
Patches currently in -mm which might be from walken@xxxxxxxxxx are
origin.patch
prio_tree-remove-fix.patch
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