250 lines
7.5 KiB
C
250 lines
7.5 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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(C) 2012 Michel Lespinasse <walken@google.com>
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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/include/linux/rbtree_augmented.h
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*/
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#ifndef _LINUX_RBTREE_AUGMENTED_H
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#define _LINUX_RBTREE_AUGMENTED_H
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#include <linux/compiler.h>
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#include <linux/rbtree.h>
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/*
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* Please note - only struct rb_augment_callbacks and the prototypes for
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* rb_insert_augmented() and rb_erase_augmented() are intended to be public.
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* The rest are implementation details you are not expected to depend on.
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*
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* See Documentation/rbtree.txt for documentation and samples.
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*/
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struct rb_augment_callbacks {
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void (*propagate)(struct rb_node *node, struct rb_node *stop);
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void (*copy)(struct rb_node *old, struct rb_node *new);
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void (*rotate)(struct rb_node *old, struct rb_node *new);
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};
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extern void __rb_insert_augmented(struct rb_node *node, struct rb_root *root,
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void (*augment_rotate)(struct rb_node *old, struct rb_node *new));
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/*
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* Fixup the rbtree and update the augmented information when rebalancing.
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*
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* On insertion, the user must update the augmented information on the path
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* leading to the inserted node, then call rb_link_node() as usual and
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* rb_augment_inserted() instead of the usual rb_insert_color() call.
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* If rb_augment_inserted() rebalances the rbtree, it will callback into
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* a user provided function to update the augmented information on the
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* affected subtrees.
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*/
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static inline void
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rb_insert_augmented(struct rb_node *node, struct rb_root *root,
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const struct rb_augment_callbacks *augment)
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{
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__rb_insert_augmented(node, root, augment->rotate);
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}
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#define RB_DECLARE_CALLBACKS(rbstatic, rbname, rbstruct, rbfield, \
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rbtype, rbaugmented, rbcompute) \
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static inline void \
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rbname ## _propagate(struct rb_node *rb, struct rb_node *stop) \
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{ \
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while (rb != stop) { \
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rbstruct *node = rb_entry(rb, rbstruct, rbfield); \
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rbtype augmented = rbcompute(node); \
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if (node->rbaugmented == augmented) \
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break; \
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node->rbaugmented = augmented; \
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rb = rb_parent(&node->rbfield); \
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} \
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} \
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static inline void \
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rbname ## _copy(struct rb_node *rb_old, struct rb_node *rb_new) \
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{ \
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rbstruct *old = rb_entry(rb_old, rbstruct, rbfield); \
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rbstruct *new = rb_entry(rb_new, rbstruct, rbfield); \
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new->rbaugmented = old->rbaugmented; \
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} \
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static void \
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rbname ## _rotate(struct rb_node *rb_old, struct rb_node *rb_new) \
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{ \
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rbstruct *old = rb_entry(rb_old, rbstruct, rbfield); \
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rbstruct *new = rb_entry(rb_new, rbstruct, rbfield); \
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new->rbaugmented = old->rbaugmented; \
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old->rbaugmented = rbcompute(old); \
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} \
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rbstatic const struct rb_augment_callbacks rbname = { \
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rbname ## _propagate, rbname ## _copy, rbname ## _rotate \
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};
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#define RB_RED 0
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#define RB_BLACK 1
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#define __rb_parent(pc) ((struct rb_node *)(pc & ~3))
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#define __rb_color(pc) ((pc) & 1)
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#define __rb_is_black(pc) __rb_color(pc)
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#define __rb_is_red(pc) (!__rb_color(pc))
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#define rb_color(rb) __rb_color((rb)->__rb_parent_color)
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#define rb_is_red(rb) __rb_is_red((rb)->__rb_parent_color)
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#define rb_is_black(rb) __rb_is_black((rb)->__rb_parent_color)
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static inline void rb_set_parent(struct rb_node *rb, struct rb_node *p)
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{
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rb->__rb_parent_color = rb_color(rb) | (unsigned long)p;
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}
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static inline void rb_set_parent_color(struct rb_node *rb,
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struct rb_node *p, int color)
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{
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rb->__rb_parent_color = (unsigned long)p | color;
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}
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static inline void
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__rb_change_child(struct rb_node *old, struct rb_node *new,
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struct rb_node *parent, struct rb_root *root)
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{
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if (parent) {
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if (parent->rb_left == old)
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WRITE_ONCE(parent->rb_left, new);
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else
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WRITE_ONCE(parent->rb_right, new);
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} else
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WRITE_ONCE(root->rb_node, new);
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}
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extern void __rb_erase_color(struct rb_node *parent, struct rb_root *root,
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void (*augment_rotate)(struct rb_node *old, struct rb_node *new));
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static __always_inline struct rb_node *
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__rb_erase_augmented(struct rb_node *node, struct rb_root *root,
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const struct rb_augment_callbacks *augment)
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{
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struct rb_node *child = node->rb_right;
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struct rb_node *tmp = node->rb_left;
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struct rb_node *parent, *rebalance;
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unsigned long pc;
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if (!tmp) {
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/*
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* Case 1: node to erase has no more than 1 child (easy!)
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*
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* Note that if there is one child it must be red due to 5)
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* and node must be black due to 4). We adjust colors locally
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* so as to bypass __rb_erase_color() later on.
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*/
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pc = node->__rb_parent_color;
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parent = __rb_parent(pc);
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__rb_change_child(node, child, parent, root);
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if (child) {
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child->__rb_parent_color = pc;
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rebalance = NULL;
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} else
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rebalance = __rb_is_black(pc) ? parent : NULL;
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tmp = parent;
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} else if (!child) {
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/* Still case 1, but this time the child is node->rb_left */
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tmp->__rb_parent_color = pc = node->__rb_parent_color;
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parent = __rb_parent(pc);
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__rb_change_child(node, tmp, parent, root);
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rebalance = NULL;
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tmp = parent;
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} else {
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struct rb_node *successor = child, *child2;
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tmp = child->rb_left;
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if (!tmp) {
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/*
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* Case 2: node's successor is its right child
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*
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* (n) (s)
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* / \ / \
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* (x) (s) -> (x) (c)
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* \
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* (c)
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*/
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parent = successor;
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child2 = successor->rb_right;
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augment->copy(node, successor);
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} else {
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/*
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* Case 3: node's successor is leftmost under
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* node's right child subtree
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*
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* (n) (s)
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* / \ / \
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* (x) (y) -> (x) (y)
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* / /
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* (p) (p)
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* / /
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* (s) (c)
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* \
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* (c)
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*/
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do {
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parent = successor;
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successor = tmp;
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tmp = tmp->rb_left;
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} while (tmp);
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child2 = successor->rb_right;
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WRITE_ONCE(parent->rb_left, child2);
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WRITE_ONCE(successor->rb_right, child);
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rb_set_parent(child, successor);
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augment->copy(node, successor);
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augment->propagate(parent, successor);
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}
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tmp = node->rb_left;
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WRITE_ONCE(successor->rb_left, tmp);
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rb_set_parent(tmp, successor);
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pc = node->__rb_parent_color;
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tmp = __rb_parent(pc);
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__rb_change_child(node, successor, tmp, root);
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if (child2) {
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successor->__rb_parent_color = pc;
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rb_set_parent_color(child2, parent, RB_BLACK);
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rebalance = NULL;
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} else {
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unsigned long pc2 = successor->__rb_parent_color;
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successor->__rb_parent_color = pc;
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rebalance = __rb_is_black(pc2) ? parent : NULL;
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}
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tmp = successor;
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}
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augment->propagate(tmp, NULL);
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return rebalance;
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}
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static __always_inline void
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rb_erase_augmented(struct rb_node *node, struct rb_root *root,
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const struct rb_augment_callbacks *augment)
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{
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struct rb_node *rebalance = __rb_erase_augmented(node, root, augment);
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if (rebalance)
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__rb_erase_color(rebalance, root, augment->rotate);
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}
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#endif /* _LINUX_RBTREE_AUGMENTED_H */
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