listhead数据结构.doc

1. 双向链表(list)
linux内核中的双向链表通过结构 struct list_head来将各个节点连接起来,此结构会作为链表元素结构中的一个参数:
struct list_head {
struct list_head *next, *prev;
};
链表头的初始化,注意,结构中的指针为NULL并不是初始化,而是指向自身才是初始化,如果只是按普通情况下的置为NULL,而不是指向自身,系统会崩溃,这是一个容易犯的错误:
#define LIST_HEAD_INIT(name) { &(name), &(name) }
#define LIST_HEAD(name) \
struct list_head name = LIST_HEAD_INIT(name)
#define INIT_LIST_HEAD(ptr) do { \
(ptr)->next = (ptr); (ptr)->prev = (ptr); \
} while (0)
最常用的链表操作:
插入到链表头:
void list_add(struct list_head *new, struct list_head *head);
插入到链表尾:
void list_add_tail(struct list_head *new, struct list_head *head);
删除链表节点:
void list_del(struct list_head *entry);
将节点移动到另一链表:
void list_move(struct list_head *list, struct list_head *head);
将节点移动到链表尾:
void list_move_tail(struct list_head *list,struct list_head *head);
判断链表是否为空,返回1为空,0非空
int list_empty(struct list_head *head);
把两个链表拼接起来:
void list_splice(struct list_head *list, struct list_head *head);
取得节点指针:
#define list_entry(ptr, type, member) \
((type *)((char *)(ptr)-(unsigned long)(&((type *)0)->member)))
遍历链表中每个节点:
#define list_for_each(pos, head) \
for (pos = (head)->next, prefetch(pos->next); pos != (head); \
pos = pos->next, prefetch(pos->next))
逆向循环链表中每个节点:
#define list_for_each_prev(pos, head) \
for (pos = (head)->prev, prefetch(pos->prev); pos != (head); \
pos = pos->prev, prefetch(po