| /* 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 struct rb_node * |
| rb_erase_cached(struct rb_node *node, struct rb_root_cached *root) |
| { |
| struct rb_node *leftmost = NULL; |
| |
| if (root->rb_leftmost == node) |
| leftmost = root->rb_leftmost = rb_next(node); |
| |
| rb_erase(node, &root->rb_root); |
| |
| return leftmost; |
| } |
| |
| 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); |
| } |
| |
| /* |
| * The below helper functions use 2 operators with 3 different |
| * calling conventions. The operators are related like: |
| * |
| * comp(a->key,b) < 0 := less(a,b) |
| * comp(a->key,b) > 0 := less(b,a) |
| * comp(a->key,b) == 0 := !less(a,b) && !less(b,a) |
| * |
| * If these operators define a partial order on the elements we make no |
| * guarantee on which of the elements matching the key is found. See |
| * rb_find(). |
| * |
| * The reason for this is to allow the find() interface without requiring an |
| * on-stack dummy object, which might not be feasible due to object size. |
| */ |
| |
| /** |
| * rb_add_cached() - insert @node into the leftmost cached tree @tree |
| * @node: node to insert |
| * @tree: leftmost cached tree to insert @node into |
| * @less: operator defining the (partial) node order |
| * |
| * Returns @node when it is the new leftmost, or NULL. |
| */ |
| static __always_inline struct rb_node * |
| rb_add_cached(struct rb_node *node, struct rb_root_cached *tree, |
| bool (*less)(struct rb_node *, const struct rb_node *)) |
| { |
| struct rb_node **link = &tree->rb_root.rb_node; |
| struct rb_node *parent = NULL; |
| bool leftmost = true; |
| |
| while (*link) { |
| parent = *link; |
| if (less(node, parent)) { |
| link = &parent->rb_left; |
| } else { |
| link = &parent->rb_right; |
| leftmost = false; |
| } |
| } |
| |
| rb_link_node(node, parent, link); |
| rb_insert_color_cached(node, tree, leftmost); |
| |
| return leftmost ? node : NULL; |
| } |
| |
| /** |
| * rb_add() - insert @node into @tree |
| * @node: node to insert |
| * @tree: tree to insert @node into |
| * @less: operator defining the (partial) node order |
| */ |
| static __always_inline void |
| rb_add(struct rb_node *node, struct rb_root *tree, |
| bool (*less)(struct rb_node *, const struct rb_node *)) |
| { |
| struct rb_node **link = &tree->rb_node; |
| struct rb_node *parent = NULL; |
| |
| while (*link) { |
| parent = *link; |
| if (less(node, parent)) |
| link = &parent->rb_left; |
| else |
| link = &parent->rb_right; |
| } |
| |
| rb_link_node(node, parent, link); |
| rb_insert_color(node, tree); |
| } |
| |
| /** |
| * rb_find_add() - find equivalent @node in @tree, or add @node |
| * @node: node to look-for / insert |
| * @tree: tree to search / modify |
| * @cmp: operator defining the node order |
| * |
| * Returns the rb_node matching @node, or NULL when no match is found and @node |
| * is inserted. |
| */ |
| static __always_inline struct rb_node * |
| rb_find_add(struct rb_node *node, struct rb_root *tree, |
| int (*cmp)(struct rb_node *, const struct rb_node *)) |
| { |
| struct rb_node **link = &tree->rb_node; |
| struct rb_node *parent = NULL; |
| int c; |
| |
| while (*link) { |
| parent = *link; |
| c = cmp(node, parent); |
| |
| if (c < 0) |
| link = &parent->rb_left; |
| else if (c > 0) |
| link = &parent->rb_right; |
| else |
| return parent; |
| } |
| |
| rb_link_node(node, parent, link); |
| rb_insert_color(node, tree); |
| return NULL; |
| } |
| |
| /** |
| * rb_find() - find @key in tree @tree |
| * @key: key to match |
| * @tree: tree to search |
| * @cmp: operator defining the node order |
| * |
| * Returns the rb_node matching @key or NULL. |
| */ |
| static __always_inline struct rb_node * |
| rb_find(const void *key, const struct rb_root *tree, |
| int (*cmp)(const void *key, const struct rb_node *)) |
| { |
| struct rb_node *node = tree->rb_node; |
| |
| while (node) { |
| int c = cmp(key, node); |
| |
| if (c < 0) |
| node = node->rb_left; |
| else if (c > 0) |
| node = node->rb_right; |
| else |
| return node; |
| } |
| |
| return NULL; |
| } |
| |
| /** |
| * rb_find_first() - find the first @key in @tree |
| * @key: key to match |
| * @tree: tree to search |
| * @cmp: operator defining node order |
| * |
| * Returns the leftmost node matching @key, or NULL. |
| */ |
| static __always_inline struct rb_node * |
| rb_find_first(const void *key, const struct rb_root *tree, |
| int (*cmp)(const void *key, const struct rb_node *)) |
| { |
| struct rb_node *node = tree->rb_node; |
| struct rb_node *match = NULL; |
| |
| while (node) { |
| int c = cmp(key, node); |
| |
| if (c <= 0) { |
| if (!c) |
| match = node; |
| node = node->rb_left; |
| } else if (c > 0) { |
| node = node->rb_right; |
| } |
| } |
| |
| return match; |
| } |
| |
| /** |
| * rb_next_match() - find the next @key in @tree |
| * @key: key to match |
| * @tree: tree to search |
| * @cmp: operator defining node order |
| * |
| * Returns the next node matching @key, or NULL. |
| */ |
| static __always_inline struct rb_node * |
| rb_next_match(const void *key, struct rb_node *node, |
| int (*cmp)(const void *key, const struct rb_node *)) |
| { |
| node = rb_next(node); |
| if (node && cmp(key, node)) |
| node = NULL; |
| return node; |
| } |
| |
| /** |
| * rb_for_each() - iterates a subtree matching @key |
| * @node: iterator |
| * @key: key to match |
| * @tree: tree to search |
| * @cmp: operator defining node order |
| */ |
| #define rb_for_each(node, key, tree, cmp) \ |
| for ((node) = rb_find_first((key), (tree), (cmp)); \ |
| (node); (node) = rb_next_match((key), (node), (cmp))) |
| |
| #endif /* _LINUX_RBTREE_H */ |