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- /* SPDX-License-Identifier: GPL-2.0-or-later */
- /*
- Red Black Trees
- (C) 1999 Andrea Arcangeli <andrea@suse.de>
-
- linux/include/linux/rbtree.h
- To use rbtrees you'll have to implement your own insert and search cores.
- This will avoid us to use callbacks and to drop drammatically performances.
- I know it's not the cleaner way, but in C (not in C++) to get
- performances and genericity...
- See Documentation/core-api/rbtree.rst for documentation and samples.
- */
- #ifndef _LINUX_RBTREE_H
- #define _LINUX_RBTREE_H
- #include <linux/kernel.h>
- #include <linux/stddef.h>
- #include <linux/rcupdate.h>
- struct rb_node {
- unsigned long __rb_parent_color;
- struct rb_node *rb_right;
- struct rb_node *rb_left;
- } __attribute__((aligned(sizeof(long))));
- /* The alignment might seem pointless, but allegedly CRIS needs it */
- struct rb_root {
- struct rb_node *rb_node;
- };
- #define rb_parent(r) ((struct rb_node *)((r)->__rb_parent_color & ~3))
- #define RB_ROOT (struct rb_root) { NULL, }
- #define rb_entry(ptr, type, member) container_of(ptr, type, member)
- #define RB_EMPTY_ROOT(root) (READ_ONCE((root)->rb_node) == NULL)
- /* 'empty' nodes are nodes that are known not to be inserted in an rbtree */
- #define RB_EMPTY_NODE(node) \
- ((node)->__rb_parent_color == (unsigned long)(node))
- #define RB_CLEAR_NODE(node) \
- ((node)->__rb_parent_color = (unsigned long)(node))
- extern void rb_insert_color(struct rb_node *, struct rb_root *);
- extern void rb_erase(struct rb_node *, struct rb_root *);
- /* Find logical next and previous nodes in a tree */
- extern struct rb_node *rb_next(const struct rb_node *);
- extern struct rb_node *rb_prev(const struct rb_node *);
- extern struct rb_node *rb_first(const struct rb_root *);
- extern struct rb_node *rb_last(const struct rb_root *);
- /* Postorder iteration - always visit the parent after its children */
- extern struct rb_node *rb_first_postorder(const struct rb_root *);
- extern struct rb_node *rb_next_postorder(const struct rb_node *);
- /* Fast replacement of a single node without remove/rebalance/add/rebalance */
- extern void rb_replace_node(struct rb_node *victim, struct rb_node *new,
- struct rb_root *root);
- extern void rb_replace_node_rcu(struct rb_node *victim, struct rb_node *new,
- struct rb_root *root);
- static inline void rb_link_node(struct rb_node *node, struct rb_node *parent,
- struct rb_node **rb_link)
- {
- node->__rb_parent_color = (unsigned long)parent;
- node->rb_left = node->rb_right = NULL;
- *rb_link = node;
- }
- static inline void rb_link_node_rcu(struct rb_node *node, struct rb_node *parent,
- struct rb_node **rb_link)
- {
- node->__rb_parent_color = (unsigned long)parent;
- node->rb_left = node->rb_right = NULL;
- rcu_assign_pointer(*rb_link, node);
- }
- #define rb_entry_safe(ptr, type, member) \
- ({ typeof(ptr) ____ptr = (ptr); \
- ____ptr ? rb_entry(____ptr, type, member) : NULL; \
- })
- /**
- * rbtree_postorder_for_each_entry_safe - iterate in post-order over rb_root of
- * given type allowing the backing memory of @pos to be invalidated
- *
- * @pos: the 'type *' to use as a loop cursor.
- * @n: another 'type *' to use as temporary storage
- * @root: 'rb_root *' of the rbtree.
- * @field: the name of the rb_node field within 'type'.
- *
- * rbtree_postorder_for_each_entry_safe() provides a similar guarantee as
- * list_for_each_entry_safe() and allows the iteration to continue independent
- * of changes to @pos by the body of the loop.
- *
- * Note, however, that it cannot handle other modifications that re-order the
- * rbtree it is iterating over. This includes calling rb_erase() on @pos, as
- * rb_erase() may rebalance the tree, causing us to miss some nodes.
- */
- #define rbtree_postorder_for_each_entry_safe(pos, n, root, field) \
- for (pos = rb_entry_safe(rb_first_postorder(root), typeof(*pos), field); \
- pos && ({ n = rb_entry_safe(rb_next_postorder(&pos->field), \
- typeof(*pos), field); 1; }); \
- pos = n)
- /*
- * Leftmost-cached rbtrees.
- *
- * We do not cache the rightmost node based on footprint
- * size vs number of potential users that could benefit
- * from O(1) rb_last(). Just not worth it, users that want
- * this feature can always implement the logic explicitly.
- * Furthermore, users that want to cache both pointers may
- * find it a bit asymmetric, but that's ok.
- */
- struct rb_root_cached {
- struct rb_root rb_root;
- struct rb_node *rb_leftmost;
- };
- #define RB_ROOT_CACHED (struct rb_root_cached) { {NULL, }, NULL }
- /* Same as rb_first(), but O(1) */
- #define rb_first_cached(root) (root)->rb_leftmost
- static inline void rb_insert_color_cached(struct rb_node *node,
- struct rb_root_cached *root,
- bool leftmost)
- {
- if (leftmost)
- root->rb_leftmost = node;
- rb_insert_color(node, &root->rb_root);
- }
- static inline void rb_erase_cached(struct rb_node *node,
- struct rb_root_cached *root)
- {
- if (root->rb_leftmost == node)
- root->rb_leftmost = rb_next(node);
- rb_erase(node, &root->rb_root);
- }
- static inline void rb_replace_node_cached(struct rb_node *victim,
- struct rb_node *new,
- struct rb_root_cached *root)
- {
- if (root->rb_leftmost == victim)
- root->rb_leftmost = new;
- rb_replace_node(victim, new, &root->rb_root);
- }
- #endif /* _LINUX_RBTREE_H */
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