335 lines
8.9 KiB
C
335 lines
8.9 KiB
C
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/* SPDX-License-Identifier: GPL-2.0-or-later */
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/*
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Red Black Trees
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(C) 1999 Andrea Arcangeli <andrea@suse.de>
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linux/include/linux/rbtree.h
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To use rbtrees you'll have to implement your own insert and search cores.
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This will avoid us to use callbacks and to drop drammatically performances.
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I know it's not the cleaner way, but in C (not in C++) to get
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performances and genericity...
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See Documentation/core-api/rbtree.rst for documentation and samples.
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*/
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#ifndef _LINUX_RBTREE_H
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#define _LINUX_RBTREE_H
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#include <linux/container_of.h>
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#include <linux/rbtree_types.h>
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#include <linux/stddef.h>
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#include <linux/rcupdate.h>
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#define rb_parent(r) ((struct rb_node *)((r)->__rb_parent_color & ~3))
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#define rb_entry(ptr, type, member) container_of(ptr, type, member)
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#define RB_EMPTY_ROOT(root) (READ_ONCE((root)->rb_node) == NULL)
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/* 'empty' nodes are nodes that are known not to be inserted in an rbtree */
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#define RB_EMPTY_NODE(node) \
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((node)->__rb_parent_color == (unsigned long)(node))
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#define RB_CLEAR_NODE(node) \
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((node)->__rb_parent_color = (unsigned long)(node))
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extern void rb_insert_color(struct rb_node *, struct rb_root *);
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extern void rb_erase(struct rb_node *, struct rb_root *);
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/* Find logical next and previous nodes in a tree */
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extern struct rb_node *rb_next(const struct rb_node *);
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extern struct rb_node *rb_prev(const struct rb_node *);
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extern struct rb_node *rb_first(const struct rb_root *);
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extern struct rb_node *rb_last(const struct rb_root *);
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/* Postorder iteration - always visit the parent after its children */
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extern struct rb_node *rb_first_postorder(const struct rb_root *);
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extern struct rb_node *rb_next_postorder(const struct rb_node *);
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/* Fast replacement of a single node without remove/rebalance/add/rebalance */
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extern void rb_replace_node(struct rb_node *victim, struct rb_node *new,
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struct rb_root *root);
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extern void rb_replace_node_rcu(struct rb_node *victim, struct rb_node *new,
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struct rb_root *root);
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static inline void rb_link_node(struct rb_node *node, struct rb_node *parent,
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struct rb_node **rb_link)
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{
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node->__rb_parent_color = (unsigned long)parent;
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node->rb_left = node->rb_right = NULL;
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*rb_link = node;
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}
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static inline void rb_link_node_rcu(struct rb_node *node, struct rb_node *parent,
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struct rb_node **rb_link)
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{
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node->__rb_parent_color = (unsigned long)parent;
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node->rb_left = node->rb_right = NULL;
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rcu_assign_pointer(*rb_link, node);
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}
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#define rb_entry_safe(ptr, type, member) \
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({ typeof(ptr) ____ptr = (ptr); \
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____ptr ? rb_entry(____ptr, type, member) : NULL; \
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})
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/**
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* rbtree_postorder_for_each_entry_safe - iterate in post-order over rb_root of
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* given type allowing the backing memory of @pos to be invalidated
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*
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* @pos: the 'type *' to use as a loop cursor.
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* @n: another 'type *' to use as temporary storage
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* @root: 'rb_root *' of the rbtree.
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* @field: the name of the rb_node field within 'type'.
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*
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* rbtree_postorder_for_each_entry_safe() provides a similar guarantee as
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* list_for_each_entry_safe() and allows the iteration to continue independent
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* of changes to @pos by the body of the loop.
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*
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* Note, however, that it cannot handle other modifications that re-order the
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* rbtree it is iterating over. This includes calling rb_erase() on @pos, as
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* rb_erase() may rebalance the tree, causing us to miss some nodes.
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*/
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#define rbtree_postorder_for_each_entry_safe(pos, n, root, field) \
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for (pos = rb_entry_safe(rb_first_postorder(root), typeof(*pos), field); \
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pos && ({ n = rb_entry_safe(rb_next_postorder(&pos->field), \
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typeof(*pos), field); 1; }); \
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pos = n)
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/* Same as rb_first(), but O(1) */
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#define rb_first_cached(root) (root)->rb_leftmost
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static inline void rb_insert_color_cached(struct rb_node *node,
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struct rb_root_cached *root,
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bool leftmost)
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{
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if (leftmost)
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root->rb_leftmost = node;
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rb_insert_color(node, &root->rb_root);
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}
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static inline struct rb_node *
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rb_erase_cached(struct rb_node *node, struct rb_root_cached *root)
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{
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struct rb_node *leftmost = NULL;
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if (root->rb_leftmost == node)
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leftmost = root->rb_leftmost = rb_next(node);
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rb_erase(node, &root->rb_root);
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return leftmost;
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}
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static inline void rb_replace_node_cached(struct rb_node *victim,
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struct rb_node *new,
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struct rb_root_cached *root)
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{
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if (root->rb_leftmost == victim)
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root->rb_leftmost = new;
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rb_replace_node(victim, new, &root->rb_root);
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}
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/*
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* The below helper functions use 2 operators with 3 different
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* calling conventions. The operators are related like:
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*
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* comp(a->key,b) < 0 := less(a,b)
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* comp(a->key,b) > 0 := less(b,a)
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* comp(a->key,b) == 0 := !less(a,b) && !less(b,a)
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*
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* If these operators define a partial order on the elements we make no
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* guarantee on which of the elements matching the key is found. See
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* rb_find().
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*
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* The reason for this is to allow the find() interface without requiring an
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* on-stack dummy object, which might not be feasible due to object size.
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*/
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/**
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* rb_add_cached() - insert @node into the leftmost cached tree @tree
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* @node: node to insert
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* @tree: leftmost cached tree to insert @node into
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* @less: operator defining the (partial) node order
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*
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* Returns @node when it is the new leftmost, or NULL.
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*/
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static __always_inline struct rb_node *
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rb_add_cached(struct rb_node *node, struct rb_root_cached *tree,
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bool (*less)(struct rb_node *, const struct rb_node *))
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{
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struct rb_node **link = &tree->rb_root.rb_node;
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struct rb_node *parent = NULL;
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bool leftmost = true;
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while (*link) {
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parent = *link;
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if (less(node, parent)) {
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link = &parent->rb_left;
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} else {
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link = &parent->rb_right;
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leftmost = false;
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}
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}
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rb_link_node(node, parent, link);
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rb_insert_color_cached(node, tree, leftmost);
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return leftmost ? node : NULL;
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}
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/**
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* rb_add() - insert @node into @tree
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* @node: node to insert
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* @tree: tree to insert @node into
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* @less: operator defining the (partial) node order
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*/
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static __always_inline void
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rb_add(struct rb_node *node, struct rb_root *tree,
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bool (*less)(struct rb_node *, const struct rb_node *))
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{
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struct rb_node **link = &tree->rb_node;
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struct rb_node *parent = NULL;
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while (*link) {
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parent = *link;
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if (less(node, parent))
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link = &parent->rb_left;
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else
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link = &parent->rb_right;
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}
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rb_link_node(node, parent, link);
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rb_insert_color(node, tree);
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}
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/**
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* rb_find_add() - find equivalent @node in @tree, or add @node
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* @node: node to look-for / insert
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* @tree: tree to search / modify
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* @cmp: operator defining the node order
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*
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* Returns the rb_node matching @node, or NULL when no match is found and @node
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* is inserted.
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*/
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static __always_inline struct rb_node *
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rb_find_add(struct rb_node *node, struct rb_root *tree,
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int (*cmp)(struct rb_node *, const struct rb_node *))
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{
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struct rb_node **link = &tree->rb_node;
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struct rb_node *parent = NULL;
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int c;
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while (*link) {
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parent = *link;
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c = cmp(node, parent);
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if (c < 0)
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link = &parent->rb_left;
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else if (c > 0)
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link = &parent->rb_right;
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else
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return parent;
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}
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rb_link_node(node, parent, link);
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rb_insert_color(node, tree);
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return NULL;
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}
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/**
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* rb_find() - find @key in tree @tree
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* @key: key to match
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* @tree: tree to search
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* @cmp: operator defining the node order
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*
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* Returns the rb_node matching @key or NULL.
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*/
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static __always_inline struct rb_node *
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rb_find(const void *key, const struct rb_root *tree,
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int (*cmp)(const void *key, const struct rb_node *))
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{
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struct rb_node *node = tree->rb_node;
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while (node) {
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int c = cmp(key, node);
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if (c < 0)
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node = node->rb_left;
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else if (c > 0)
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node = node->rb_right;
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else
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return node;
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}
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return NULL;
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}
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/**
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* rb_find_first() - find the first @key in @tree
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* @key: key to match
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* @tree: tree to search
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* @cmp: operator defining node order
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*
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* Returns the leftmost node matching @key, or NULL.
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*/
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static __always_inline struct rb_node *
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rb_find_first(const void *key, const struct rb_root *tree,
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int (*cmp)(const void *key, const struct rb_node *))
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{
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struct rb_node *node = tree->rb_node;
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struct rb_node *match = NULL;
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while (node) {
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int c = cmp(key, node);
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if (c <= 0) {
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if (!c)
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match = node;
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node = node->rb_left;
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} else if (c > 0) {
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node = node->rb_right;
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}
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}
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return match;
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}
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/**
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* rb_next_match() - find the next @key in @tree
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* @key: key to match
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* @tree: tree to search
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* @cmp: operator defining node order
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*
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* Returns the next node matching @key, or NULL.
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*/
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static __always_inline struct rb_node *
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rb_next_match(const void *key, struct rb_node *node,
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int (*cmp)(const void *key, const struct rb_node *))
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{
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node = rb_next(node);
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if (node && cmp(key, node))
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node = NULL;
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return node;
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}
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/**
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* rb_for_each() - iterates a subtree matching @key
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* @node: iterator
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* @key: key to match
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* @tree: tree to search
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* @cmp: operator defining node order
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*/
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#define rb_for_each(node, key, tree, cmp) \
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for ((node) = rb_find_first((key), (tree), (cmp)); \
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(node); (node) = rb_next_match((key), (node), (cmp)))
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#endif /* _LINUX_RBTREE_H */
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