linux内核双向链表list的使用

list.h文件

#ifndef __TONGYISHU_LIST_H
#define __TONGYISHU_LIST_H

#undef offsetof
#define offsetof(TYPE, MEMBER) ((size_t) &((TYPE *)0)->MEMBER)

/**
 * 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.
 *
 */
#undef container_of
#define container_of(ptr, type, member) ({                      
    const typeof( ((type *)0)->member ) *__mptr = (ptr);    
    (type *)( (char *)__mptr - offsetof(type,member) );})


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

#undef LIST_HEAD_INIT
#define LIST_HEAD_INIT(name) 
    do { 
        (name).prev = &(name); 
        (name).next = &(name); 
    } while (0)

/**
 * 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.
 */
#undef list_entry
#define list_entry(ptr, type, member) 
    container_of(ptr, type, member)

/**
 * list_for_each_entry    -    iterate over list of given type
 * @pos:    the type * to use as a loop cursor.
 * @head:    the head for your list.
 * @member:    the name of the list_struct within the struct.
 */
#undef list_for_each_entry
#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 cursor.
 * @n:        another type * to use as temporary storage
 * @head:    the head for your list.
 * @member:    the name of the list_struct within the struct.
 */
#undef list_for_each_entry_safe
#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))

/**
 * list_empty - tests whether a list is empty
 * @head: the list to test.
 */
static inline int list_empty(const struct list_head *head)
{
    return head->next == head;
}

/*
 * Insert a new entry between two known consecutive entries.
 *
 * This is only for internal list manipulation where we know
 * the prev/next entries already!
 */
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_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.
 */
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!
 */
static inline void __list_del(struct list_head *prev, struct list_head *next)
{
    next->prev = prev;
    prev->next = next;
}

#undef LIST_POISON1
#define LIST_POISON1  ((void *) 0x00100100)
#undef LIST_POISON2
#define LIST_POISON2  ((void *) 0x00200200)

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

main.c文件

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

struct Staff {
    struct list_head list;
    char id[10];
    char name[20];
};

int main()
{
    struct Staff staff_head = { 0 };
    struct Staff *pos = NULL, *next = NULL;
    LIST_HEAD_INIT(staff_head.list);

    /* list add */
    printf("%s", ">>>>>>> list add start.
");
    for (int i = 0; i < 3; i++) {
        pos = (struct Staff*)malloc(sizeof(struct Staff));
        sprintf(pos->id, "%s%d", "t0051260", i);
        sprintf(pos->name, "%s%d", "tongyishu-", i);
        list_add_tail(&pos->list, &staff_head.list);
        printf("> add list node : 
");
        printf("  id   : %s
", pos->id);
        printf("  name : %s
", pos->name);
    }
    printf("%s", ">>>>>>> list add end.
");

    /* list for each */
    printf("%s", ">>>>>>> list for each start.
");
    list_for_each_entry(pos, &staff_head.list, list)
    {
        printf("  id : %s
", pos->id);
        printf("  name : %s
", pos->name);
    }
    printf("%s", ">>>>>>> list for each end.
");

    /* delete node("t00512601", "tongyishu-1") */
    printf("%s", ">>>>>>> delete node start.
");
    list_for_each_entry_safe(pos, next, &staff_head.list, list)
    {
        if (strcmp("t00512601", pos->id) == 0) {
            list_del(&pos->list);
            printf("> delete list node : 
");
            printf("  id   : %s
", pos->id);
            printf("  name : %s
", pos->name);
            free(pos);
        }
    }
    printf("%s", ">>>>>>> delete node end.
");

    /* list for each again */
    printf("%s", ">>>>>>> list for each after delete node start.
");
    list_for_each_entry(pos, &staff_head.list, list)
    {
        printf("  id   : %s
", pos->id);
        printf("  name : %s
", pos->name);
    }
    printf("%s", ">>>>>>> list for each after delete node end.
");


    /* release resource */
    printf("%s", ">>>>>>> release resource start.
");
    list_for_each_entry_safe(pos, next, &staff_head.list, list)
    {
        list_del(&pos->list);
        free(pos);
    }
    printf("%s", ">>>>>>> release resource end.
");

    return 0;
}

输出结果：

>>>>>>> list add start.
> add list node :
  id   : t00512600
  name : tongyishu-0
> add list node :
  id   : t00512601
  name : tongyishu-1
> add list node :
  id   : t00512602
  name : tongyishu-2
>>>>>>> list add end.
>>>>>>> list for each start.
  id : t00512600
  name : tongyishu-0
  id : t00512601
  name : tongyishu-1
  id : t00512602
  name : tongyishu-2
>>>>>>> list for each end.
>>>>>>> delete node start.
> delete list node :
  id   : t00512601
  name : tongyishu-1
>>>>>>> delete node end.
>>>>>>> list for each after delete node start.
  id   : t00512600
  name : tongyishu-0
  id   : t00512602
  name : tongyishu-2
>>>>>>> list for each after delete node end.
>>>>>>> release resource start.
>>>>>>> release resource end.