(笔记)linux内核链表实现（含示例）

 

背景：Linux内核实现的是双向循环链表，提供了链表操作的基本功能(参见my_list.h)。

 

一、my_list.h（链表实现）

#ifndef __MY_LIST_H__
#define __MY_LIST_H__

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

#define INIT_LIST_HEAD(ptr) do { \
    (ptr)->next = (ptr); \
    (ptr)->prev = (ptr); \
} while(0)

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_add_tail(struct list_head *new, struct list_head *head)
{
    __list_add(new, head->prev, head);
}

static inline void __list_del(struct list_head * prev, struct list_head * next)
{
    next->prev = prev;
    prev->next = next;
}

#define LIST_POISON1  ((void *) 0x0)
#define LIST_POISON2  ((void *) 0x0)

static inline void list_del(struct list_head *entry)
{
    __list_del(entry->prev, entry->next);
    entry->next = LIST_POISON1;
    entry->prev = LIST_POISON2;
}

static inline int list_empty(const struct list_head *head)
{
    return head->next == head;
}

#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) );})

#define list_entry(ptr, type, member) \
    container_of(ptr, type, member)

#define list_for_each(pos, head) \
    for (pos = (head)->next; pos != (head); pos = pos->next)

#define list_for_each_safe(pos, n, head) \
    for (pos = (head)->next, n = pos->next; pos != (head); \
        pos = n, n = pos->next)

#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))

#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

 

二、my_list.c（链表使用示例）

#include <stdio.h>

#include <stdio.h>
#include <string.h>
#include <stdlib.h>

#include "my_list.h"

//定义链表大结构体
typedef struct Student 
{
    struct list_head list;

    unsigned int id;
    char name[32];
    unsigned int score;
} T_Student;

struct list_head g_stu_list;


int main(int argc, char* argv[])
{
    char tmp[32] = { 0 };
　　
    //初始化链表
    INIT_LIST_HEAD(&g_stu_list);

    int i = 0;
    for (i = 1; i <= 5; i++)
    {
        T_Student* pstu = NULL;
        pstu = (T_Student*)malloc(sizeof(T_Student));

        memset(pstu, 0, sizeof(T_Student));
        pstu->id = i;
        memset(tmp, 0, sizeof(tmp));
        snprintf(tmp, sizeof(tmp) - 1, "mt-0%d", i);
        strcpy(pstu->name, tmp);
        pstu->score = 90 + i;
        printf("i: %d, id: %d, name: %s, score: %d, &list = %p\n", i, pstu->id, pstu->name, pstu->score, &pstu->list);

        list_add(&pstu->list, &g_stu_list);
    }
    printf("\r\n");
    
    
    printf("........................list_for_each start....................\n");
    struct list_head* pos = NULL, * temp = NULL;
    T_Student* pstu = NULL, * pstuTemp = NULL;
    list_for_each(pos, &g_stu_list)
    {
        pstu = list_entry(pos, T_Student, list);
        printf("id: %d---name: %s---score: %d\n", pstu->id, pstu->name, pstu->score);
    }
    printf("........................list_for_each end....................\n");
    printf("\r\n");
    
    
    printf("........................list_for_each_safe start....................\n");
    list_for_each_safe(pos, temp, &g_stu_list)
    {
        pstu = list_entry(pos, T_Student, list);
        printf("id: %d---name: %s---score: %d\n", pstu->id, pstu->name, pstu->score);

    }
    printf("........................list_for_each_safe end....................\n");
    printf("\r\n");
    
    
    printf("........................list_for_each_entry start....................\n");
    list_for_each_entry(pstu, &g_stu_list, list)
    {
        printf(">>>>id: %d---name: %s---score: %d\n", pstu->id, pstu->name, pstu->score);
    }
    printf("........................list_for_each_entry end....................\n");
    printf("\r\n");
    
    
    printf("........................list_for_each_entry_safe start....................\n");
    list_for_each_entry_safe(pstu, pstuTemp, &g_stu_list, list)
    {
        printf(">>>>id: %d---name: %s---score: %d\n", pstu->id, pstu->name, pstu->score);
    }
    printf("........................list_for_each_entry_safe end....................\n");
    printf("\r\n");
    
    
    printf("........................list_for_each_safe delete node start....................\n");
    //list_for_each(pos, &g_stu_list) //list_for_each遍历时若删除了pos指向的当前元素，则会导致pos节点的prev和next指针从链表断开，无法继续遍历，
    list_for_each_safe(pos, temp, &g_stu_list)
    {
        pstu = list_entry(pos, T_Student, list);
        printf("id: %d---name: %s---score: %d\n", pstu->id, pstu->name, pstu->score);
        if (pstu->id == 4) //delete node
        {
            list_del(&pstu->list);
        }
    }
    
    
    printf("........................list_for_each_safe delete and print list....................\n");
    list_for_each_safe(pos, temp, &g_stu_list)
    {
        pstu = list_entry(pos, T_Student, list);
        printf("id: %d---name: %s---score: %d\n", pstu->id, pstu->name, pstu->score);
    }
    printf("........................list_for_each_safe delete node end....................\n");
    return 0;
}

 

三、链表示例运行结果