Linux内核链表 list_head学习笔记_head_list

Linux内核链表 list_head学习笔记

kernel/inclue/linux/types.h中定义的list_head结构如下

struct list_head {
	struct list_head *next, *prev;
};
//list_head为包含指针的结构体
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---

• 链表创建

Linux内核中的定义：

---

#define LIST_HEAD_INIT(name) { &(name), &(name) }
//括号内参数为地址/指针

#define LIST_HEAD(name) \
	struct list_head name = LIST_HEAD_INIT(name)
//LIST_HEAD(name) 即为创建一个名为‘name’的list_head结构体，即链表头,pre和next指针都指向自己

	static inline void INIT_LIST_HEAD(struct list_head *list)
{
	WRITE_ONCE(list->next, list);
	list->prev = list;
}
//已经创建了所需的结构体地址
```c
LIST_HEAD(name);
//等价于
struct list_head name = {&name,  &name} ;   
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实际应用：list_head单独使用没有意义，需要再嵌套入结构体中，加入所需的可赋值变量

• 创建结构体：

struct birthday {
	int day;
	int month;
	int year;
	struct list_head list;
}
//嵌套了list_head的结构体birthday
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先创建链表头

static LIST_HEAD(header);
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创建首节点

1. 方法一：

struct birthday me={
.day=22,
.month=8,
.2000,
.list=LIST_HEAD_INIT(me.list);
};
//#define LIST_HEAD_INIT(name) { &(name), &(name) }
//LIST_HEAD_INIT(name)代表一个大括号及其俩地址
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而后将此节点插入header之后

list_add_tail(&me.list,&birthday.list);
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2. 方法二

struct birthday *me;
me.day=22;
me.month=8;
me.2000;
INIT_LIST_HEAD(&me.list);
//#define LIST_HEAD_INIT(name) { &(name), &(name) }
//LIST_HEAD_INIT(name)代表一个大括号及其俩地址
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而后将此节点插入header之后

list_add_tail(&me.list,&birthday.list);
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---

链表操作

---

• 插入节点

list_add 和list_add_tail区别：

---

• 删除节点

list_del(struct list_head *entry);
//删除链表中的任意节点
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e.g.:

list_del(&me.list);
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---

• 链表遍历(只是list_head的遍历)
  内核中的遍历方式

从前向后遍历

#define list_for_each(pos, head) \
	for (pos = (head)->next; pos != (head); pos = pos->next)
//从前向后遍历
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从后向前遍历

#define list_for_each_prev(pos, head) \
	for (pos = (head)->prev; pos != (head); pos = pos->prev)
//从后向前遍历
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---

• 宿主结构（包含list_head的结构体）

• 找出宿主结构

container_of(ptr, type, member)
//根据结构体重的一个成员变量地址导出包含这个成员变量member的struct地址
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---

• 宿主结构的遍历

获取链表的首元素

list_first_entry(ptr, type, member)
// get the first element from a list
/**
 * list_first_entry - get the first element from a list
 * @ptr:	the list head to take the element from.
 * @type:	the type of the struct this is embedded in.
 * @member:	the name of the list_head within the struct.
 *
 * Note, that list is expected to be not empty.
 */

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获取链表的next

list_next_entry(pos, member)
// get the next element from a list

/**
 * list_next_entry - get the next element in list
 * @pos:	the type * to cursor（确定指针类型）
 * @member:	the name of the list_head within the struct.
 */
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遍历结构体

list_for_each_entry(pos, head, member)	
//pos只是用来typeof获得结构类型
#define list_for_each_entry(pos, head, member)				\
for (pos = list_first_entry(head, typeof(*pos), member);	\
	     &pos->member != (head);					\
	     pos = list_next_entry(pos, member))
/**
 * list_for_each_entry	-	iterate over list of given type
 * @pos:	the type * to use as a loop cursor.（确定指针类型）
 * @head:	the head for your list.
 * @member:	the name of the list_head within the struct.
 */
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e.g.

struct birthday *ptr;
list_for_each_entry(ptr,&birthday_list,list)
{ 
         printk ("val =  %d\n" , ptr->val); 
}
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资料source:CSDN博主：风亦路 All Rights Reserved
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