55a63998b8
Tfour 4 redundant if-conditions in function __rb_erase_color() in
lib/rbtree.c are removed.
In pseudo-source-code, the structure of the code is as follows:
if ((!A || B) && (!C || D)) {
.
.
.
} else {
if (!C || D) {//if this is true, it implies: (A == true) && (B == false)
if (A) {//hence this always evaluates to 'true'...
.
}
.
//at this point, C always becomes true, because of:
__rb_rotate_right/left();
//and:
other = parent->rb_right/left;
}
.
.
if (C) {//...and this too !
.
}
}
Signed-off-by: Wolfram Strepp <wstrepp@gmx.de>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Andrea Arcangeli <andrea@qumranet.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
391 lines
8.5 KiB
C
391 lines
8.5 KiB
C
/*
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Red Black Trees
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(C) 1999 Andrea Arcangeli <andrea@suse.de>
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(C) 2002 David Woodhouse <dwmw2@infradead.org>
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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linux/lib/rbtree.c
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*/
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#include <linux/rbtree.h>
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#include <linux/module.h>
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static void __rb_rotate_left(struct rb_node *node, struct rb_root *root)
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{
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struct rb_node *right = node->rb_right;
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struct rb_node *parent = rb_parent(node);
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if ((node->rb_right = right->rb_left))
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rb_set_parent(right->rb_left, node);
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right->rb_left = node;
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rb_set_parent(right, parent);
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if (parent)
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{
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if (node == parent->rb_left)
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parent->rb_left = right;
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else
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parent->rb_right = right;
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}
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else
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root->rb_node = right;
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rb_set_parent(node, right);
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}
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static void __rb_rotate_right(struct rb_node *node, struct rb_root *root)
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{
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struct rb_node *left = node->rb_left;
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struct rb_node *parent = rb_parent(node);
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if ((node->rb_left = left->rb_right))
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rb_set_parent(left->rb_right, node);
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left->rb_right = node;
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rb_set_parent(left, parent);
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if (parent)
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{
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if (node == parent->rb_right)
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parent->rb_right = left;
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else
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parent->rb_left = left;
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}
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else
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root->rb_node = left;
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rb_set_parent(node, left);
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}
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void rb_insert_color(struct rb_node *node, struct rb_root *root)
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{
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struct rb_node *parent, *gparent;
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while ((parent = rb_parent(node)) && rb_is_red(parent))
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{
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gparent = rb_parent(parent);
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if (parent == gparent->rb_left)
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{
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{
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register struct rb_node *uncle = gparent->rb_right;
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if (uncle && rb_is_red(uncle))
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{
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rb_set_black(uncle);
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rb_set_black(parent);
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rb_set_red(gparent);
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node = gparent;
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continue;
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}
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}
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if (parent->rb_right == node)
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{
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register struct rb_node *tmp;
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__rb_rotate_left(parent, root);
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tmp = parent;
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parent = node;
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node = tmp;
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}
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rb_set_black(parent);
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rb_set_red(gparent);
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__rb_rotate_right(gparent, root);
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} else {
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{
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register struct rb_node *uncle = gparent->rb_left;
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if (uncle && rb_is_red(uncle))
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{
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rb_set_black(uncle);
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rb_set_black(parent);
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rb_set_red(gparent);
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node = gparent;
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continue;
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}
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}
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if (parent->rb_left == node)
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{
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register struct rb_node *tmp;
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__rb_rotate_right(parent, root);
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tmp = parent;
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parent = node;
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node = tmp;
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}
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rb_set_black(parent);
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rb_set_red(gparent);
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__rb_rotate_left(gparent, root);
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}
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}
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rb_set_black(root->rb_node);
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}
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EXPORT_SYMBOL(rb_insert_color);
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static void __rb_erase_color(struct rb_node *node, struct rb_node *parent,
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struct rb_root *root)
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{
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struct rb_node *other;
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while ((!node || rb_is_black(node)) && node != root->rb_node)
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{
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if (parent->rb_left == node)
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{
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other = parent->rb_right;
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if (rb_is_red(other))
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{
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rb_set_black(other);
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rb_set_red(parent);
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__rb_rotate_left(parent, root);
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other = parent->rb_right;
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}
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if ((!other->rb_left || rb_is_black(other->rb_left)) &&
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(!other->rb_right || rb_is_black(other->rb_right)))
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{
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rb_set_red(other);
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node = parent;
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parent = rb_parent(node);
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}
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else
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{
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if (!other->rb_right || rb_is_black(other->rb_right))
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{
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rb_set_black(other->rb_left);
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rb_set_red(other);
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__rb_rotate_right(other, root);
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other = parent->rb_right;
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}
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rb_set_color(other, rb_color(parent));
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rb_set_black(parent);
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rb_set_black(other->rb_right);
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__rb_rotate_left(parent, root);
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node = root->rb_node;
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break;
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}
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}
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else
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{
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other = parent->rb_left;
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if (rb_is_red(other))
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{
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rb_set_black(other);
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rb_set_red(parent);
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__rb_rotate_right(parent, root);
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other = parent->rb_left;
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}
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if ((!other->rb_left || rb_is_black(other->rb_left)) &&
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(!other->rb_right || rb_is_black(other->rb_right)))
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{
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rb_set_red(other);
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node = parent;
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parent = rb_parent(node);
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}
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else
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{
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if (!other->rb_left || rb_is_black(other->rb_left))
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{
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rb_set_black(other->rb_right);
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rb_set_red(other);
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__rb_rotate_left(other, root);
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other = parent->rb_left;
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}
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rb_set_color(other, rb_color(parent));
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rb_set_black(parent);
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rb_set_black(other->rb_left);
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__rb_rotate_right(parent, root);
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node = root->rb_node;
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break;
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}
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}
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}
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if (node)
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rb_set_black(node);
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}
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void rb_erase(struct rb_node *node, struct rb_root *root)
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{
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struct rb_node *child, *parent;
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int color;
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if (!node->rb_left)
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child = node->rb_right;
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else if (!node->rb_right)
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child = node->rb_left;
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else
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{
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struct rb_node *old = node, *left;
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node = node->rb_right;
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while ((left = node->rb_left) != NULL)
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node = left;
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child = node->rb_right;
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parent = rb_parent(node);
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color = rb_color(node);
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if (child)
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rb_set_parent(child, parent);
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if (parent == old) {
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parent->rb_right = child;
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parent = node;
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} else
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parent->rb_left = child;
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node->rb_parent_color = old->rb_parent_color;
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node->rb_right = old->rb_right;
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node->rb_left = old->rb_left;
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if (rb_parent(old))
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{
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if (rb_parent(old)->rb_left == old)
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rb_parent(old)->rb_left = node;
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else
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rb_parent(old)->rb_right = node;
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} else
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root->rb_node = node;
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rb_set_parent(old->rb_left, node);
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if (old->rb_right)
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rb_set_parent(old->rb_right, node);
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goto color;
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}
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parent = rb_parent(node);
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color = rb_color(node);
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if (child)
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rb_set_parent(child, parent);
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if (parent)
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{
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if (parent->rb_left == node)
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parent->rb_left = child;
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else
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parent->rb_right = child;
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}
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else
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root->rb_node = child;
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color:
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if (color == RB_BLACK)
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__rb_erase_color(child, parent, root);
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}
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EXPORT_SYMBOL(rb_erase);
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/*
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* This function returns the first node (in sort order) of the tree.
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*/
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struct rb_node *rb_first(const struct rb_root *root)
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{
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struct rb_node *n;
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n = root->rb_node;
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if (!n)
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return NULL;
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while (n->rb_left)
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n = n->rb_left;
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return n;
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}
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EXPORT_SYMBOL(rb_first);
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struct rb_node *rb_last(const struct rb_root *root)
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{
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struct rb_node *n;
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n = root->rb_node;
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if (!n)
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return NULL;
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while (n->rb_right)
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n = n->rb_right;
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return n;
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}
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EXPORT_SYMBOL(rb_last);
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struct rb_node *rb_next(const struct rb_node *node)
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{
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struct rb_node *parent;
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if (rb_parent(node) == node)
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return NULL;
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/* If we have a right-hand child, go down and then left as far
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as we can. */
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if (node->rb_right) {
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node = node->rb_right;
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while (node->rb_left)
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node=node->rb_left;
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return (struct rb_node *)node;
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}
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/* No right-hand children. Everything down and left is
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smaller than us, so any 'next' node must be in the general
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direction of our parent. Go up the tree; any time the
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ancestor is a right-hand child of its parent, keep going
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up. First time it's a left-hand child of its parent, said
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parent is our 'next' node. */
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while ((parent = rb_parent(node)) && node == parent->rb_right)
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node = parent;
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return parent;
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}
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EXPORT_SYMBOL(rb_next);
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struct rb_node *rb_prev(const struct rb_node *node)
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{
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struct rb_node *parent;
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if (rb_parent(node) == node)
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return NULL;
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/* If we have a left-hand child, go down and then right as far
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as we can. */
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if (node->rb_left) {
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node = node->rb_left;
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while (node->rb_right)
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node=node->rb_right;
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return (struct rb_node *)node;
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}
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/* No left-hand children. Go up till we find an ancestor which
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is a right-hand child of its parent */
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while ((parent = rb_parent(node)) && node == parent->rb_left)
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node = parent;
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return parent;
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}
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EXPORT_SYMBOL(rb_prev);
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void rb_replace_node(struct rb_node *victim, struct rb_node *new,
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struct rb_root *root)
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{
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struct rb_node *parent = rb_parent(victim);
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/* Set the surrounding nodes to point to the replacement */
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if (parent) {
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if (victim == parent->rb_left)
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parent->rb_left = new;
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else
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parent->rb_right = new;
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} else {
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root->rb_node = new;
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}
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if (victim->rb_left)
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rb_set_parent(victim->rb_left, new);
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if (victim->rb_right)
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rb_set_parent(victim->rb_right, new);
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/* Copy the pointers/colour from the victim to the replacement */
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*new = *victim;
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}
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EXPORT_SYMBOL(rb_replace_node);
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