[转载]Linux内核list_head学习（二）

前一篇文章讨论了list_head 结构的基本结构和实现原理，本文主要介绍一下实例代码。

自己如果想在应用程序中使用list_head 的相应操作（当然应该没人使用了，C++ STL提供了list 用起来貌似更方便），在应用程序中需要包含自己的 "list.h" 头文件：

/*

注：这个list.h 是为了配合示例程序而建的，内容来自：linux/include/linux/list.h 和相关文件

*/

#ifndef _LINUX_LIST_H

#define _LINUX_LIST_H

struct list_head {

         struct list_head *next, *prev;

};

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

#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) );})

static inline void INIT_LIST_HEAD(struct list_head *list)

{

        list->next = list;

        list->prev = list;

}

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;

}

static inline void list_add(struct list_head *new, struct list_head *head)

{

        __list_add(new, head, head->next);

}

static inline void __list_del(struct list_head * prev, struct list_head * next)

{

        next->prev = prev;

        prev->next = next;

}

static inline void list_del(struct list_head *entry)

{

        __list_del(entry->prev, entry->next);

        entry->next = NULL;

        entry->prev = NULL;

}

#define prefetch(x) __builtin_prefetch(x)

//注：这里prefetch 是gcc的一个优化，也可以不要

#define list_for_each(pos, head) \

         for (pos = (head)->next; prefetch(pos->next), pos != (head); \

                 pos = pos->next)

#define list_entry(ptr, type, member) \

         container_of(ptr, type, member)

#endif

写了一个简单的应用程序：

#include "list.h"

#include <stdio.h>

#include <string.h>

#define MAX_NAME_LEN 32

#define MAX_ID_LEN 10

typedef struct stud

{

    struct list_head list;

    char name[MAX_NAME_LEN];

    char stu_number[MAX_ID_LEN];

}num_n_stu;

int main(void)

{

    struct list_head head;

    num_n_stu stu_1;

    num_n_stu stu_2;

    num_n_stu *entry;

    struct list_head *p;

    INIT_LIST_HEAD(&head);

    strcpy(stu_1.name,"lisi");

    strcpy(stu_1.stu_number,"10000000");

    strcpy(stu_2.name,"zhangsan");

    strcpy(stu_2.stu_number,"10000001");

    list_add(&stu_1.list,&head);

    list_add(&stu_2.list,&head);

    list_del(&stu_2.list);

    list_for_each(p,&head)

    {

        entry=list_entry(p,struct stud,list);

        printf("name: %s\n",entry->name);

        printf("stu_number: %s\n",entry->stu_number);

    }

    list_del(&stu_1.list);

    return 0;

}

在Linux内核中可以使用这个以类似驱动模块的形式加载到内核：（这里就不用使用自定义的list.h了）

#include <linux/list.h>

#include <linux/init.h>

#include <linux/module.h>

MODULE_LICENSE("GPL");

#define MAX_NAME_LEN 32

#define MAX_ID_LEN 10

typedef struct stud

{

    struct list_head list;

    char name[MAX_NAME_LEN];

    char stu_number[MAX_ID_LEN];

}num_n_stu;

static int my_main(void)

{

    struct list_head head;

    num_n_stu stu_1;

    num_n_stu stu_2;

    num_n_stu *entry;

    struct list_head *p;

    INIT_LIST_HEAD(&head);

    strcpy(stu_1.name,"lisi");

    strcpy(stu_1.stu_number,"10000000");

    strcpy(stu_2.name,"zhangsan");

    strcpy(stu_2.stu_number,"10000001");

    list_add(&stu_1.list,&head);

    list_add(&stu_2.list,&head);

    list_del(&stu_2.list);

    list_for_each(p,&head)

    {

        entry=list_entry(p,struct stud,list);

        printk("name: %s\n",entry->name);

        printk("stu_number: %s\n",entry->stu_number);

    }

    list_del(&stu_1.list);

    return 0;

}

static void my_exit(void)

{

    printk("my_exit ! \n");

}

module_init(my_main);

module_exit(my_exit);

巴特西

[转载]Linux内核list_head学习（二）

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