blob: 3eb99f9ed50c66fc3f9291fe26377b2da3019caa [file] [log] [blame]
SPDX-License-Identifier: GPL-2.0-or-later
Red Black Trees
(C) 1999 Andrea Arcangeli <>
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...
Some example of insert and search follows here. The search is a plain
normal search over an ordered tree. The insert instead must be implemented
int two steps: as first thing the code must insert the element in
order as a red leaf in the tree, then the support library function
rb_insert_color() must be called. Such function will do the
not trivial work to rebalance the rbtree if necessary.
static inline struct page * rb_search_page_cache(struct inode * inode,
unsigned long offset)
struct rb_node * n = inode->i_rb_page_cache.rb_node;
struct page * page;
while (n)
page = rb_entry(n, struct page, rb_page_cache);
if (offset < page->offset)
n = n->rb_left;
else if (offset > page->offset)
n = n->rb_right;
return page;
return NULL;
static inline struct page * __rb_insert_page_cache(struct inode * inode,
unsigned long offset,
struct rb_node * node)
struct rb_node ** p = &inode->i_rb_page_cache.rb_node;
struct rb_node * parent = NULL;
struct page * page;
while (*p)
parent = *p;
page = rb_entry(parent, struct page, rb_page_cache);
if (offset < page->offset)
p = &(*p)->rb_left;
else if (offset > page->offset)
p = &(*p)->rb_right;
return page;
rb_link_node(node, parent, p);
return NULL;
static inline struct page * rb_insert_page_cache(struct inode * inode,
unsigned long offset,
struct rb_node * node)
struct page * ret;
if ((ret = __rb_insert_page_cache(inode, offset, node)))
goto out;
rb_insert_color(node, &inode->i_rb_page_cache);
return ret;
#include <stddef.h>
* container_of - cast a member of a structure out to the containing structure
* @ptr: the pointer to the member.
* @type: the type of the container struct this is embedded in.
* @member: the name of the member within the struct.
#define container_of(ptr, type, member) ({ \
const typeof( ((type *)0)->member ) *__mptr = (ptr); \
(type *)( (char *)__mptr - offsetof(type,member) );})
struct rb_node
unsigned long rb_parent_color;
#define RB_RED 0
#define RB_BLACK 1
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_color(r) ((r)->rb_parent_color & 1)
#define rb_is_red(r) (!rb_color(r))
#define rb_is_black(r) rb_color(r)
#define rb_set_red(r) do { (r)->rb_parent_color &= ~1; } while (0)
#define rb_set_black(r) do { (r)->rb_parent_color |= 1; } while (0)
static inline void rb_set_parent(struct rb_node *rb, struct rb_node *p)
rb->rb_parent_color = (rb->rb_parent_color & 3) | (unsigned long)p;
static inline void rb_set_color(struct rb_node *rb, int color)
rb->rb_parent_color = (rb->rb_parent_color & ~1) | color;
#define RB_ROOT (struct rb_root) { NULL, }
#define rb_entry(ptr, type, member) container_of(ptr, type, member)
#define RB_EMPTY_ROOT(root) ((root)->rb_node == NULL)
#define RB_EMPTY_NODE(node) (rb_parent(node) == node)
#define RB_CLEAR_NODE(node) (rb_set_parent(node, 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 *);
/* 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);
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;
#endif /* _LINUX_RBTREE_H */