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![Peter Zijlstra](/assets/img/avatar_default.png)
Reimplement augmented RB-trees without sprinkling extra branches all over the RB-tree code (which lives in the scheduler hot path). This approach is 'borrowed' from Fabio's BFQ implementation and relies on traversing the rebalance path after the RB-tree-op to correct the heap property for insertion/removal and make up for the damage done by the tree rotations. For insertion the rebalance path is trivially that from the new node upwards to the root, for removal it is that from the deepest node in the path from the to be removed node that will still be around after the removal. [ This patch also fixes a video driver regression reported by Ali Gholami Rudi - the memtype->subtree_max_end was updated incorrectly. ] Acked-by: Suresh Siddha <suresh.b.siddha@intel.com> Acked-by: Venkatesh Pallipadi <venki@google.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Tested-by: Ali Gholami Rudi <ali@rudi.ir> Cc: Fabio Checconi <fabio@gandalf.sssup.it> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> LKML-Reference: <1275414172.27810.27961.camel@twins> Signed-off-by: Ingo Molnar <mingo@elte.hu>
459 lines
9.9 KiB
C
459 lines
9.9 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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if (rb_parent(old)) {
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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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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 (parent == old) {
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parent = node;
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} else {
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if (child)
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rb_set_parent(child, parent);
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parent->rb_left = child;
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node->rb_right = old->rb_right;
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rb_set_parent(old->rb_right, node);
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}
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node->rb_parent_color = old->rb_parent_color;
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node->rb_left = old->rb_left;
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rb_set_parent(old->rb_left, 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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static void rb_augment_path(struct rb_node *node, rb_augment_f func, void *data)
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{
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struct rb_node *parent;
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up:
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func(node, data);
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parent = rb_parent(node);
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if (!parent)
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return;
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if (node == parent->rb_left && parent->rb_right)
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func(parent->rb_right, data);
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else if (parent->rb_left)
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func(parent->rb_left, data);
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node = parent;
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goto up;
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}
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/*
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* after inserting @node into the tree, update the tree to account for
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* both the new entry and any damage done by rebalance
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*/
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void rb_augment_insert(struct rb_node *node, rb_augment_f func, void *data)
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{
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if (node->rb_left)
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node = node->rb_left;
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else if (node->rb_right)
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node = node->rb_right;
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rb_augment_path(node, func, data);
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}
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/*
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* before removing the node, find the deepest node on the rebalance path
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* that will still be there after @node gets removed
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*/
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struct rb_node *rb_augment_erase_begin(struct rb_node *node)
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{
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struct rb_node *deepest;
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if (!node->rb_right && !node->rb_left)
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deepest = rb_parent(node);
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else if (!node->rb_right)
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deepest = node->rb_left;
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else if (!node->rb_left)
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deepest = node->rb_right;
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else {
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deepest = rb_next(node);
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if (deepest->rb_right)
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deepest = deepest->rb_right;
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else if (rb_parent(deepest) != node)
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deepest = rb_parent(deepest);
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}
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return deepest;
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}
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/*
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* after removal, update the tree to account for the removed entry
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* and any rebalance damage.
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*/
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void rb_augment_erase_end(struct rb_node *node, rb_augment_f func, void *data)
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{
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if (node)
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rb_augment_path(node, func, data);
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}
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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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