mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-08-27 19:29:37 +00:00
![Peter Zijlstra](/assets/img/avatar_default.png)
Reduce rbtree boiler plate by using the new helpers. Make rb_add_cached() / rb_erase_cached() return a pointer to the leftmost node to aid in updating additional state. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Acked-by: Davidlohr Bueso <dbueso@suse.de>
361 lines
9.7 KiB
C
361 lines
9.7 KiB
C
/* 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 */
|