Linux 内核链表

1.内核头文件

#ifndef __DLIST_H
#define __DLIST_H

/* This file is from Linux Kernel (include/linux/list.h)
   * and modified by simply removing hardware prefetching of list items.
   * Here by copyright, credits attributed to wherever they belong.
   * Kulesh Shanmugasundaram (kulesh [squiggly] isis.poly.edu)
   */

/*
   * Simple doubly linked list implementation.
   *
   * Some of the internal functions (“__xxx”) are useful when
   * manipulating whole lists rather than single entries, as
   * sometimes we already know the next/prev entries and we can
   * generate better code by using them directly rather than
   * using the generic single-entry routines.
   */
/**
   * 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 offsetof(TYPE, MEMBER) ((size_t) &((TYPE *)0)->MEMBER)

#define container_of(ptr, type, member) ({			\
		        const typeof( ((type *)0)->member ) *__mptr = (ptr);	\
		        (type *)( (char *)__mptr - offsetof(type,member) );})
/*
    * These are non-NULL pointers that will result in page faults
	 * under normal circumstances, used to verify that nobody uses
	  * non-initialized list entries.
	   */
#define LIST_POISON1  ((void *) 0x00100100)
#define LIST_POISON2  ((void *) 0x00200200)

struct list_head {
		struct list_head *next, *prev;
};

#define LIST_HEAD_INIT(name) { &(name), &(name) }

//定义一个节点，并将两个指针域自己指向自己
#define LIST_HEAD(name) \
	struct list_head name = LIST_HEAD_INIT(name)

//将传入的ptr指向的节点的两个指针域自己指向自己
#define INIT_LIST_HEAD(ptr) do { \
		(ptr)->next = (ptr); (ptr)->prev = (ptr); \
} while (0)

/*
   * Insert a new entry between two known consecutive entries.
   *
   * This is only for internal list manipulation where we know
   * the prev/next entries already!
   */

//将节点new插入到节点prev和next之间
static inline void __list_add(struct list_head *new,
						struct list_head *prev,
										struct list_head *next)
{
		next->prev = new;
			new->next = next;
				new->prev = prev;
					prev->next = new;
}

/**
  * list_add – add a new entry
  * @new: new entry to be added
  * @head: list head to add it after
  *
  * Insert a new entry after the specified head.
  * This is good for implementing stacks.
  */
//将new节点插入到一个链表头结点head的后边（头插入）
static inline void list_add(struct list_head *new, struct list_head *head)
{
		__list_add(new, head, head->next);
}

/**
  * list_add_tail – add a new entry
  * @new: new entry to be added
  * @head: list head to add it before
  *
  * Insert a new entry before the specified head.
  * This is useful for implementing queues.
  */
//将new节点插入到一个链表头结点head的前边（尾插入）
static inline void list_add_tail(struct list_head *new, struct list_head *head)
{
		__list_add(new, head->prev, head);
}

/*
   * Delete a list entry by making the prev/next entries
   * point to each other.
   *
   * This is only for internal list manipulation where we know
   * the prev/next entries already!
   */
//删除节点prev和next之间的节点
static inline void __list_del(struct list_head *prev, struct list_head *next)
{
		next->prev = prev;
			prev->next = next;
}

/**
  * list_del – deletes entry from list.
  * @entry: the element to delete from the list.
  * Note: list_empty on entry does not return true after this, the entry is in an undefined state.
  */
//删除节点entry，并将entry的两个指针域设为NULL;
static inline void list_del(struct list_head *entry)
{
		__list_del(entry->prev, entry->next);
			entry->next = (void *) 0;
				entry->prev = (void *) 0;
}

/**
  * list_del_init – deletes entry from list and reinitialize it.
  * @entry: the element to delete from the list.
  */
//删除节点entry，并将entry的两个指针域自己指向自己;
static inline void list_del_init(struct list_head *entry)
{
		__list_del(entry->prev, entry->next);
			INIT_LIST_HEAD(entry);
}

/**
  * list_move – delete from one list and add as another’s head
  * @list: the entry to move
  * @head: the head that will precede our entry
  */

//删除list节点，并将list节点插入到head头结点的后边
static inline void list_move(struct list_head *list,
						struct list_head *head)
{
		__list_del(list->prev, list->next);
			list_add(list, head);
}

/**
  * list_move_tail – delete from one list and add as another’s tail
  * @list: the entry to move
  * @head: the head that will follow our entry
  */
//删除list节点，并将list节点插入到head头结点的前边
static inline void list_move_tail(struct list_head *list,
							struct list_head *head)
{
		__list_del(list->prev, list->next);
			list_add_tail(list, head);
}

/**
  * list_empty – tests whether a list is empty
  * @head: the list to test.
  */

//判断内核链表是否为空
static inline int list_empty(struct list_head *head)
{
		return head->next == head;
}


//将头结点为list和头结点为head的两个链表进行合并，舍弃list头节点
static inline void __list_splice(struct list_head *list,
							struct list_head *head)
{
		struct list_head *first = list->next;
			struct list_head *last = list->prev;
				struct list_head *at = head->next;

					first->prev = head;
						head->next = first;

							last->next = at;
								at->prev = last;
}

/**
  * list_splice – join two lists
  * @list: the new list to add.
  * @head: the place to add it in the first list.
  */
static inline void list_splice(struct list_head *list, struct list_head *head)
{
	if (!list_empty(list))
		__list_splice(list, head);
}

/**
  * list_splice_init – join two lists and reinitialise the emptied list.
  * @list: the new list to add.
  * @head: the place to add it in the first list.
  *
  * The list at @list is reinitialised
  */
//将头结点为list和头结点为head的两个链表进行合并，舍弃list头节点
//并将list头结点的指针域自己指向自己
static inline void list_splice_init(struct list_head *list,
		struct list_head *head)
{
	if (!list_empty(list)) {
		__list_splice(list, head);
		INIT_LIST_HEAD(list);
	}
}

/**
  * list_entry – get the struct for this entry
  * @ptr:    the &struct list_head pointer.
  * @type:    the type of the struct this is embedded in.
  * @member:    the name of the list_struct within the struct.
  */
//ptr:指向小结构体的指针
//type:大结构体的类型
//member:小结构体的变量成员
/*
	struct test{
			int data;
			struct list_head member;
	}typedef type struct test;
								*/

//通过小结构体来获得大结构体的数据
//小结构体的实际地址 - 小结构体相对于大结构体的偏移量
//宏的返回值：大结构体的实际地址。
#define list_entry(ptr, type, member) \
	((type *)((char *)(ptr)-(unsigned long)(&((type *)0)->member)))

/**
  * list_for_each    -    iterate over a list
  * @pos:    the &struct list_head to use as a loop counter.
  * @head:    the head for your list.
  */
//对小结构体的遍历，从前向后
//pos是指向小结构体的遍历指针，head为小结构体头结点
#define list_for_each(pos, head) \
	for (pos = (head)->next; pos != (head); \
			pos = pos->next)
/**
  * list_for_each_prev    -    iterate over a list backwards
  * @pos:    the &struct list_head to use as a loop counter.
  * @head:    the head for your list.
  */
//对小结构体的遍历，从后向前
#define list_for_each_prev(pos, head) \
	for (pos = (head)->prev; pos != (head); \
			pos = pos->prev)

/**
  * list_for_each_safe    -    iterate over a list safe against removal of list entry
  * @pos:    the &struct list_head to use as a loop counter.
  * @n:        another &struct list_head to use as temporary storage
  * @head:    the head for your list.
  */
//对小结构体的遍历,当遍历当前节点时，记住下一个节点，防止断链。
#define list_for_each_safe(pos, n, head) \
	for (pos = (head)->next, n = pos->next; pos != (head); \
			pos = n, n = pos->next)

/**
  * list_for_each_entry    -    iterate over list of given type
  * @pos:    the type * to use as a loop counter.
  * @head:    the head for your list.
  * @member:    the name of the list_struct within the struct.
  */
//通过小结构体来实现对大结构体的遍历
//pos：大结构体的指针
//head:小结构体头结点
//member:小结构体的变量
#define list_for_each_entry(pos, head, member)                \
	for (pos = list_entry((head)->next, typeof(*pos), member);    \
			&pos->member != (head);                     \
			pos = list_entry(pos->member.next, typeof(*pos), member))

/**
  * list_for_each_entry_safe – iterate over list of given type safe against removal of list entry
  * @pos:    the type * to use as a loop counter.
  * @n:        another type * to use as temporary storage
  * @head:    the head for your list.
  * @member:    the name of the list_struct within the struct.
  */
//通过小结构体来实现对大结构体的遍历，当遍历当前节点时，记住下一个节点，防止断链。
#define list_for_each_entry_safe(pos, n, head, member)            \
	for (pos = list_entry((head)->next, typeof(*pos), member),    \
			n = list_entry(pos->member.next, typeof(*pos), member);    \
			&pos->member != (head);                     \
			pos = n, n = list_entry(n->member.next, typeof(*n), member))

#endif

2.演示Demo  

#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#include "dlist.h"


typedef struct node{
	int data;
	struct list_head member;
}linknode,*plink;

int main()
{
	plink p;
	int a;
	struct list_head *tmp;
	plink pos;
	
		//1.初始化
	LIST_HEAD(head);

	scanf("%d",&a);
	while(a != -1){
		//2.分配空间
		p = (plink)malloc(sizeof(linknode));
		if(NULL == p){
			printf("malloc error\n");
			exit(1);
		}

		p->data = a;
		//3.头插入
		list_add_tail(&p->member,&head);
		scanf("%d",&a);
	}
		
		//4.遍历
#if 0
	list_for_each(tmp,&head){
		pos = list_entry(tmp,struct node,member);
		printf("%d\t",pos->data);
	}
	printf("\n");
#else
	list_for_each_entry(pos, &head, member){
		printf("%d\t", pos->data);
	}
	printf("\n");
#endif

	return 0;
}