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author | 2012-10-08 16:31:10 -0700 | |
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committer | 2012-10-09 16:22:36 +0900 | |
commit | 60670b8034d6e2ba860af79c9379b7788d09db73 (patch) | |
tree | 5fed30a98d29a03c078f756275ba34c830fee36c /lib | |
parent | rbtree: add __rb_change_child() helper function (diff) | |
download | linux-60670b8034d6e2ba860af79c9379b7788d09db73.tar.gz linux-60670b8034d6e2ba860af79c9379b7788d09db73.tar.bz2 linux-60670b8034d6e2ba860af79c9379b7788d09db73.zip |
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@google.com>
Reviewed-by: Rik van Riel <riel@redhat.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'lib')
-rw-r--r-- | lib/rbtree.c | 35 |
1 files changed, 18 insertions, 17 deletions
diff --git a/lib/rbtree.c b/lib/rbtree.c index de89a614b1ba..bde1b5c5fb33 100644 --- a/lib/rbtree.c +++ b/lib/rbtree.c @@ -368,17 +368,28 @@ static void __rb_erase_color(struct rb_node *node, struct rb_node *parent, 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, struct rb_root *root) 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); } |