linux内核链表移植详解

1、介绍

linux内核链表重要是针对：普通链表无法管理所有结构体节点串联起来；普通链表利用一种结构只能表示一个对象。加入我只想对某个节点添加某种属性int number；将会需要改变所有节点结构体。

struct list_node{

int value1;

char value2;

struct list_node *next;

struct list_node *prev;

};

改成内核链表的方式：

struct list_node{

struct list_node *next;

struct list_node *prev;

};

struct score{

int value1;

char value2;

struct list_node *head_list;

}

 2、主要的几个函数（函数实现可以直接查看后面代码）

1、内核链表的几个重要函数
(1)INIT_LIST_HEAD()创建链表
(2)list_add()在链表头插入
(3)list_add_tail
(4)list_del()
(5)list_entry()
(6)list_for_each()

用图解释一下链表头插入

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;
}
void list_add(struct list_head *new, struct list_head *head)
{
	__list_add(new, head, head->next);
}
void list_add_tail(struct list_head *new, struct list_head *head)
{
	__list_add(new, head->prev, head);
}

3、应用层代码

#include

struct list_head{
	struct list_head *prev;
	struct list_head *next;
};
struct score{
	int num;
	int englist;
	int math;
	struct list_head list;
}; 


#define prefetch(x) __builtin_prefetch(x)
#define list_for_each(pos, head) 
	for ( pos = (head)->next; prefetch(pos->next), pos != (head); pos = pos->next)


#define offsetof(TYPE, MEMBER) ((size_t) &((TYPE *)0)->MEMBER)
#define list_entry(ptr, type, member) container_of(ptr, type, member)
#define container_of(ptr, type, member) (
	{															
		const typeof( ((type *)0)->member ) *__mptr = (ptr);	
		(type *)( (char *)__mptr - offsetof(type,member) );     
	}															
)

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;
}
void list_add(struct list_head *new, struct list_head *head)
{
	__list_add(new, head, head->next);
}
void list_add_tail(struct list_head *new, struct list_head *head)
{
	__list_add(new, head->prev, head);
}

void __list_del(struct list_head * prev, struct list_head * next)
{
	next->prev = prev;
	prev->next = next;
}
void list_del(struct list_head *entry)
{
	__list_del(entry->prev, entry->next);
	entry->next = (void *) 0;
	entry->prev = (void *) 0;
}


void INIT_LIST_HEAD(struct list_head *list)
{
	list->next = list;
	list->prev = list;
}



struct list_head score_head;
struct score stu1, stu2,stu3;
struct list_head *pos;
struct score *tmp;

int main(void)
{	
	INIT_LIST_HEAD(&score_head);
	stu1.englist=99;stu1.math=98;stu1.num=1001;
	stu2.englist=9;stu2.math=8;stu2.num=1002;
	stu3.englist=69;stu3.math=68;stu3.num=1003;
	
	list_add_tail(&(stu1.list),&score_head);
	list_add_tail(&(stu2.list),&score_head);
	list_add_tail(&(stu3.list),&score_head);

	list_for_each(pos,&score_head){
		tmp=list_entry(pos,struct score,list);//这个地方list为何可以直接使用？ 
		printf("math=%dn",tmp->math); 
	}
	return 0;
}

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