链表使用
我认为熟悉内核链表功能最好的方法就是看一些简单的实例，实例是一个非常好的素材去更好的理解链表。
下面是一个例子，包含创建，添加，删除和遍历链表。
<span style="font-size:14px;"><span style="color:#330099;">#include <stdio.h>
#include <stdlib.h>
#include "list.h"
struct kool_list{
int to;
struct list_head list;
int from;
};//自定义欲链接的数据额结构，并包含双向链表结构
int main(int argc, char **argv){
struct kool_list *tmp;
struct list_head *pos, *q;
unsigned int i;
struct kool_list mylist;
INIT_LIST_HEAD(&mylist.list);//初始化一个链表表头
/* 向<span style="font-family: Arial, Helvetica, sans-serif;">mylist中添加元素</span><span style="font-family: Arial, Helvetica, sans-serif;"> */</span>
for(i=5; i!=0; --i){
tmp= (struct kool_list *)malloc(sizeof(struct kool_list));
/* INIT_LIST_HEAD(&tmp->list);
*
* this initializes a dynamically allocated list_head. we
* you can omit this if subsequent call is add_list() or
* anything along that line because the next, prev
* fields get initialized in those functions.
*/
printf("enter to and from:");
scanf("%d %d", &tmp->to, &tmp->from);
/* add the new item 'tmp' to the list of items in mylist */
list_add(&(tmp->list), &(mylist.list));//项链表中添加新的元素节点,tmp中的list
/* you can also use list_add_tail() which adds new items to
* the tail end of the list
*/
}
printf("\n");
/* now you have a circularly linked list of items of type struct kool_list.
* now let us go through the items and print them out
*/
/* list_for_each() is a macro for a for loop.
* first parameter is used as the counter in for loop. in other words, inside the
* loop it points to the current item's list_head.
* second parameter is the pointer to the list. it is not manipulated by the macro.
*/
printf("traversing the list using list_for_each()\n");
list_for_each(pos, &mylist.list){//遍历链表，pos依次指向链表的元素
/* at this point: pos->next points to the next item's 'list' variable and
* pos->prev points to the previous item's 'list' variable. Here item is
* of type struct kool_list. But we need to access the item itself not the
* variable 'list' in the item! macro list_entry() does just that. See "How
* does this work?" below for an explanation of how this is done.
*/
tmp= list_entry(pos, struct kool_list, list);//获得包含pos节点的数据结构<span style="font-family: Arial, Helvetica, sans-serif;">struct kool_list指针</span>
/* given a pointer to struct list_head, type of data structure it is part of,
* and it's name (struct list_head's name in the data structure) it returns a
* pointer to the data structure in which the pointer is part of.
* For example, in the above line list_entry() will return a pointer to the
* struct kool_list item it is embedded in!
*/
printf("to= %d from= %d\n", tmp->to, tmp->from);
}
printf("\n");
/* since this is a circularly linked list. you can traverse the list in reverse order
* as well. all you need to do is replace 'list_for_each' with 'list_for_each_prev'
* everything else remain the same!
*
* Also you can traverse the list using list_for_each_entry() to iterate over a given
* type of entries. For example:
*/
printf("traversing the list using list_for_each_entry()\n");
list_for_each_entry(tmp, &mylist.list, list)
printf("to= %d from= %d\n", tmp->to, tmp->from);
printf("\n");
/* now let's be good and free the kool_list items. since we will be removing items
* off the list using list_del() we need to use a safer version of the list_for_each()
* macro aptly named list_for_each_safe(). Note that you MUST use this macro if the loop
* involves deletions of items (or moving items from one list to another).
*/
printf("deleting the list using list_for_each_safe()\n");
list_for_each_safe(pos, q, &mylist.list){
tmp= list_entry(pos, struct kool_list, list);
printf("freeing item to= %d from= %d\n", tmp->to, tmp->from);
list_del(pos);
free(tmp);
}
return 0;
}</span>
</span><img src="http://blogimg.chinaunix.net/blog/upfile2/081023224717.jpg" alt="" />关于内核链表的常用的几个API实现，将在例说Linux内核链表（三）中介绍。
原文地址：http://blog.csdn.net/eliot_shao/article/details/40090721
