(补充实验方法) linux内核链表之实例 这个例子包括简单的增、删、遍历

linux内核链表之实例 + 实验 

参考：http://blog.csdn.net/lufeiop02/article/details/6526382

基本知识可以看这个网址

深入分析 Linux 内核链表http://www.ibm.com/developerworks/cn/linux/kernel/l-chain/

 这个例子包括简单的增、删、遍历

1. #include <linux/kernel.h>  
2. #include <linux/module.h>  
3. #include <linux/init.h>  
4. #include <linux/slab.h>  
5. #include <linux/list.h>  
6.   
7. MODULE_LICENSE("GPL");  
8. MODULE_AUTHOR("David Xie");  
9. MODULE_DESCRIPTION("List Module");  
10. MODULE_ALIAS("List module");  
11.   
12. struct student  //代表一个实际节点的结构  
13. {  
14.     char name[100];  
15.     int num;  
16.     struct list_head list;   //内核链表里的节点结构 用于链表的操作后面的entry 的实现就要用到该结构
    
17. };  
18.   
19. struct student *pstudent;        
20. struct student *tmp_student;  
21. struct list_head student_list;    
22. struct list_head *pos;  
23.   
24. int mylist_init(void)  
25. {  
26.     int i = 0;  
27.       
28.     //初始化一个链表，其实就是把student_list的prev和next指向自身  
29.     INIT_LIST_HEAD(&student_list);    
30.       
31.     pstudent = kmalloc(sizeof(struct student)*5,GFP_KERNEL);//向内核申请5个student结构空间  
32.     memset(pstudent,0,sizeof(struct student)*5); //清空，这两个函数可以由kzalloc单独做到  
33.       
34.     for(i=0;i<5;i++)  
35.     { //为结构体属性赋值  
36.         sprintf(pstudent[i].name,"Student%d",i+1);  
37.         pstudent[i].num = i+1;   
38.         //加入链表节点，list_add的话是在表头插入，list_add_tail是在表尾插入  
39.         list_add( &(pstudent[i].list), &student_list);//参数1是要插入的节点地址，参数2是链表头地址  
40.     }   
41.       
42.     list_for_each(pos,&student_list) //list_for_each用来遍历链表，这是个宏定义  
43.                                      //pos在上面有定义  
44.     {  
45.         //list_entry用来提取出内核链表节点对应的实际结构节点，即根据struct list_head来提取struct student  
46.         //第三个参数list就是student结构定义里的属性list  
47.         //list_entry的原理有点复杂，也是linux内核的一个经典实现，这个在上面那篇链接文章里也有讲解  
48.         tmp_student = list_entry(pos,struct student, list);  
49.         //打印一些信息，以备验证结果  
50.         printk("<0>student %d name: %s\n",tmp_student->num,tmp_student->name);  
51.     }  
52.       
53.     return 0;  
54. }  
55.   
56.   
57. void mylist_exit(void)  
58. {     
59.     int i ;  
60.     /* 实验：将for换成list_for_each来遍历删除结点，观察要发生的现象，并考虑解决办法 */  
61.     for(i=0;i<5;i++)  
62.     {  
63.         //额，删除节点，只要传个内核链表节点就行了  
64.         list_del(&(pstudent[i].list));       
65.     }  
66.     //释放空间 
    
67.     printk("<0> mylist_exit!\n");
    
68.     kfree(pstudent);
69.   
    
70. }  
71.   
72. module_init(mylist_init);  
73. module_exit(mylist_exit); 
    

实验方法及步骤如下：
               主机      ubuntu 10.10

       开发板  mini2440 
  
       内核       友善之臂提供的   linux-2.6.32.2

实验步骤

  1 ：cd /home/; mkdir  kernel_list   在/home目录下新建 一个 kernel_list文件夹         

  2 ： cd kernel_list ; vim kernel_list.c   新建 kernel_list.c 文件

  3  ： vim  Makefile    新建 Makefile 文件 文件内容如下

其中/home/linux-2.6.32.2 为友善提供的内核存放路径
 
  1.KERDIR = /home/linux-2.6.32.2
  2. obj-m += kernel_list.o
  3. build: kernel_modules
  4.
  5. kernel_modules:
  6.     make -C $(KERDIR) M=$(CURDIR) modules
  7. clean:
  8.     make -C $(KERDIR) M=$(CURDIR) clean


 4：make  编译内核模块

 6 ：minicom  在另外一个终端打开minicom      

              7： ftp 192.168.1.230           用ftp上传文件到开发板
                     plg
                     plg
                     bin
                     put  kernel_list.ko

 8：cd /home/plg        回到minicom 开发板的终端   进入 /home/plg  
 9：insmod  kernel_list.ko     加载 模块  

               

补充 list.h (内核链表的实现)

#ifndef _LINUX_LIST_H#define _LINUX_LIST_H#include <linux/stddef.h>#include <linux/poison.h>#include <linux/prefetch.h>#include <asm/system.h>/* * Simple doubly linked list implementation. * * Some of the internal functions ("__xxx") are useful when * manipulating whole lists rather than single entries, as * sometimes we already know the next/prev entries and we can * generate better code by using them directly rather than * using the generic single-entry routines. */struct list_head {struct list_head *next, *prev;};#define LIST_HEAD_INIT(name) { &(name), &(name) }#define LIST_HEAD(name) \struct list_head name = LIST_HEAD_INIT(name)static inline void INIT_LIST_HEAD(struct list_head *list){list->next = list;list->prev = list;}/* * Insert a new entry between two known consecutive entries. * * This is only for internal list manipulation where we know * the prev/next entries already! */#ifndef CONFIG_DEBUG_LISTstatic 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;}#elseextern void __list_add(struct list_head *new,      struct list_head *prev,      struct list_head *next);#endif/** * list_add - add a new entry * @new: new entry to be added * @head: list head to add it after * * Insert a new entry after the specified head. * This is good for implementing stacks. */static inline void list_add(struct list_head *new, struct list_head *head){__list_add(new, head, head->next);}/** * 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;}/** * 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. */#ifndef CONFIG_DEBUG_LISTstatic inline void list_del(struct list_head *entry){__list_del(entry->prev, entry->next);entry->next = LIST_POISON1;entry->prev = LIST_POISON2;}#elseextern void list_del(struct list_head *entry);#endif/** * list_replace - replace old entry by new one * @old : the element to be replaced * @new : the new element to insert * * If @old was empty, it will be overwritten. */static inline void list_replace(struct list_head *old,struct list_head *new){new->next = old->next;new->next->prev = new;new->prev = old->prev;new->prev->next = new;}static inline void list_replace_init(struct list_head *old,struct list_head *new){list_replace(old, new);INIT_LIST_HEAD(old);}/** * list_del_init - deletes entry from list and reinitialize it. * @entry: the element to delete from the list. */static inline void list_del_init(struct list_head *entry){__list_del(entry->prev, entry->next);INIT_LIST_HEAD(entry);}/** * list_move - delete from one list and add as another's head * @list: the entry to move * @head: the head that will precede our entry */static inline void list_move(struct list_head *list, struct list_head *head){__list_del(list->prev, list->next);list_add(list, head);}/** * list_move_tail - delete from one list and add as another's tail * @list: the entry to move * @head: the head that will follow our entry */static inline void list_move_tail(struct list_head *list,  struct list_head *head){__list_del(list->prev, list->next);list_add_tail(list, head);}/** * list_is_last - tests whether @list is the last entry in list @head * @list: the entry to test * @head: the head of the list */static inline int list_is_last(const struct list_head *list,const struct list_head *head){return list->next == head;}/** * 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;}/** * list_empty_careful - tests whether a list is empty and not being modified * @head: the list to test * * Description: * tests whether a list is empty _and_ checks that no other CPU might be * in the process of modifying either member (next or prev) * * NOTE: using list_empty_careful() without synchronization * can only be safe if the only activity that can happen * to the list entry is list_del_init(). Eg. it cannot be used * if another CPU could re-list_add() it. */static inline int list_empty_careful(const struct list_head *head){struct list_head *next = head->next;return (next == head) && (next == head->prev);}/** * list_is_singular - tests whether a list has just one entry. * @head: the list to test. */static inline int list_is_singular(const struct list_head *head){return !list_empty(head) && (head->next == head->prev);}static inline void __list_cut_position(struct list_head *list,struct list_head *head, struct list_head *entry){struct list_head *new_first = entry->next;list->next = head->next;list->next->prev = list;list->prev = entry;entry->next = list;head->next = new_first;new_first->prev = head;}/** * list_cut_position - cut a list into two * @list: a new list to add all removed entries * @head: a list with entries * @entry: an entry within head, could be the head itself *and if so we won't cut the list * * This helper moves the initial part of @head, up to and * including @entry, from @head to @list. You should * pass on @entry an element you know is on @head. @list * should be an empty list or a list you do not care about * losing its data. * */static inline void list_cut_position(struct list_head *list,struct list_head *head, struct list_head *entry){if (list_empty(head))return;if (list_is_singular(head) &&(head->next != entry && head != entry))return;if (entry == head)INIT_LIST_HEAD(list);else__list_cut_position(list, head, entry);}static inline void __list_splice(const struct list_head *list, struct list_head *prev, struct list_head *next){struct list_head *first = list->next;struct list_head *last = list->prev;first->prev = prev;prev->next = first;last->next = next;next->prev = last;}/** * list_splice - join two lists, this is designed for stacks * @list: the new list to add. * @head: the place to add it in the first list. */static inline void list_splice(const struct list_head *list,struct list_head *head){if (!list_empty(list))__list_splice(list, head, head->next);}/** * list_splice_tail - join two lists, each list being a queue * @list: the new list to add. * @head: the place to add it in the first list. */static inline void list_splice_tail(struct list_head *list,struct list_head *head){if (!list_empty(list))__list_splice(list, head->prev, head);}/** * list_splice_init - join two lists and reinitialise the emptied list. * @list: the new list to add. * @head: the place to add it in the first list. * * The list at @list is reinitialised */static inline void list_splice_init(struct list_head *list,    struct list_head *head){if (!list_empty(list)) {__list_splice(list, head, head->next);INIT_LIST_HEAD(list);}}/** * list_splice_tail_init - join two lists and reinitialise the emptied list * @list: the new list to add. * @head: the place to add it in the first list. * * Each of the lists is a queue. * The list at @list is reinitialised */static inline void list_splice_tail_init(struct list_head *list, struct list_head *head){if (!list_empty(list)) {__list_splice(list, head->prev, head);INIT_LIST_HEAD(list);}}/** * 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. */#define list_entry(ptr, type, member) \container_of(ptr, type, member)/** * 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_struct within the struct. * * Note, that list is expected to be not empty. */#define list_first_entry(ptr, type, member) \list_entry((ptr)->next, type, member)/** * list_for_each-iterate over a list * @pos:the &struct list_head to use as a loop cursor. * @head:the head for your list. */#define list_for_each(pos, head) \for (pos = (head)->next; prefetch(pos->next), pos != (head); \        pos = pos->next)/** * __list_for_each-iterate over a list * @pos:the &struct list_head to use as a loop cursor. * @head:the head for your list. * * This variant differs from list_for_each() in that it's the * simplest possible list iteration code, no prefetching is done. * Use this for code that knows the list to be very short (empty * or 1 entry) most of the time. */#define __list_for_each(pos, head) \for (pos = (head)->next; pos != (head); pos = pos->next)/** * list_for_each_prev-iterate over a list backwards * @pos:the &struct list_head to use as a loop cursor. * @head:the head for your list. */#define list_for_each_prev(pos, head) \for (pos = (head)->prev; prefetch(pos->prev), pos != (head); \        pos = pos->prev)/** * list_for_each_safe - iterate over a list safe against removal of list entry * @pos:the &struct list_head to use as a loop cursor. * @n:another &struct list_head to use as temporary storage * @head:the head for your list. */#define list_for_each_safe(pos, n, head) \for (pos = (head)->next, n = pos->next; pos != (head); \pos = n, n = pos->next)/** * list_for_each_prev_safe - iterate over a list backwards safe against removal of list entry * @pos:the &struct list_head to use as a loop cursor. * @n:another &struct list_head to use as temporary storage * @head:the head for your list. */#define list_for_each_prev_safe(pos, n, head) \for (pos = (head)->prev, n = pos->prev; \     prefetch(pos->prev), pos != (head); \     pos = n, n = pos->prev)/** * 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. */#define list_for_each_entry(pos, head, member)\for (pos = list_entry((head)->next, typeof(*pos), member);\     prefetch(pos->member.next), &pos->member != (head); \     pos = list_entry(pos->member.next, typeof(*pos), member))/** * list_for_each_entry_reverse - iterate backwards 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. */#define list_for_each_entry_reverse(pos, head, member)\for (pos = list_entry((head)->prev, typeof(*pos), member);\     prefetch(pos->member.prev), &pos->member != (head); \     pos = list_entry(pos->member.prev, typeof(*pos), member))/** * list_prepare_entry - prepare a pos entry for use in list_for_each_entry_continue() * @pos:the type * to use as a start point * @head:the head of the list * @member:the name of the list_struct within the struct. * * Prepares a pos entry for use as a start point in list_for_each_entry_continue(). */#define list_prepare_entry(pos, head, member) \((pos) ? : list_entry(head, typeof(*pos), member))/** * list_for_each_entry_continue - continue iteration 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. * * Continue to iterate over list of given type, continuing after * the current position. */#define list_for_each_entry_continue(pos, head, member) \for (pos = list_entry(pos->member.next, typeof(*pos), member);\     prefetch(pos->member.next), &pos->member != (head);\     pos = list_entry(pos->member.next, typeof(*pos), member))/** * list_for_each_entry_continue_reverse - iterate backwards from the given point * @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. * * Start to iterate over list of given type backwards, continuing after * the current position. */#define list_for_each_entry_continue_reverse(pos, head, member)\for (pos = list_entry(pos->member.prev, typeof(*pos), member);\     prefetch(pos->member.prev), &pos->member != (head);\     pos = list_entry(pos->member.prev, typeof(*pos), member))/** * list_for_each_entry_from - iterate over list of given type from the current point * @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. * * Iterate over list of given type, continuing from current position. */#define list_for_each_entry_from(pos, head, member) \for (; prefetch(pos->member.next), &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. */#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_for_each_entry_safe_continue * @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. * * Iterate over list of given type, continuing after current point, * safe against removal of list entry. */#define list_for_each_entry_safe_continue(pos, n, head, member) \for (pos = list_entry(pos->member.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_for_each_entry_safe_from * @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. * * Iterate over list of given type from current point, safe against * removal of list entry. */#define list_for_each_entry_safe_from(pos, n, head, member) \for (n = list_entry(pos->member.next, typeof(*pos), member);\     &pos->member != (head);\     pos = n, n = list_entry(n->member.next, typeof(*n), member))/** * list_for_each_entry_safe_reverse * @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. * * Iterate backwards over list of given type, safe against removal * of list entry. */#define list_for_each_entry_safe_reverse(pos, n, head, member)\for (pos = list_entry((head)->prev, typeof(*pos), member),\n = list_entry(pos->member.prev, typeof(*pos), member);\     &pos->member != (head); \     pos = n, n = list_entry(n->member.prev, typeof(*n), member))/* * Double linked lists with a single pointer list head. * Mostly useful for hash tables where the two pointer list head is * too wasteful. * You lose the ability to access the tail in O(1). */struct hlist_head {struct hlist_node *first;};struct hlist_node {struct hlist_node *next, **pprev;};#define HLIST_HEAD_INIT { .first = NULL }#define HLIST_HEAD(name) struct hlist_head name = {  .first = NULL }#define INIT_HLIST_HEAD(ptr) ((ptr)->first = NULL)static inline void INIT_HLIST_NODE(struct hlist_node *h){h->next = NULL;h->pprev = NULL;}static inline int hlist_unhashed(const struct hlist_node *h){return !h->pprev;}static inline int hlist_empty(const struct hlist_head *h){return !h->first;}static inline void __hlist_del(struct hlist_node *n){struct hlist_node *next = n->next;struct hlist_node **pprev = n->pprev;*pprev = next;if (next)next->pprev = pprev;}static inline void hlist_del(struct hlist_node *n){__hlist_del(n);n->next = LIST_POISON1;n->pprev = LIST_POISON2;}static inline void hlist_del_init(struct hlist_node *n){if (!hlist_unhashed(n)) {__hlist_del(n);INIT_HLIST_NODE(n);}}static inline void hlist_add_head(struct hlist_node *n, struct hlist_head *h){struct hlist_node *first = h->first;n->next = first;if (first)first->pprev = &n->next;h->first = n;n->pprev = &h->first;}/* next must be != NULL */static inline void hlist_add_before(struct hlist_node *n,struct hlist_node *next){n->pprev = next->pprev;n->next = next;next->pprev = &n->next;*(n->pprev) = n;}static inline void hlist_add_after(struct hlist_node *n,struct hlist_node *next){next->next = n->next;n->next = next;next->pprev = &n->next;if(next->next)next->next->pprev  = &next->next;}/* * Move a list from one list head to another. Fixup the pprev * reference of the first entry if it exists. */static inline void hlist_move_list(struct hlist_head *old,   struct hlist_head *new){new->first = old->first;if (new->first)new->first->pprev = &new->first;old->first = NULL;}#define hlist_entry(ptr, type, member) container_of(ptr,type,member)#define hlist_for_each(pos, head) \for (pos = (head)->first; pos && ({ prefetch(pos->next); 1; }); \     pos = pos->next)#define hlist_for_each_safe(pos, n, head) \for (pos = (head)->first; pos && ({ n = pos->next; 1; }); \     pos = n)/** * hlist_for_each_entry- iterate over list of given type * @tpos:the type * to use as a loop cursor. * @pos:the &struct hlist_node to use as a loop cursor. * @head:the head for your list. * @member:the name of the hlist_node within the struct. */#define hlist_for_each_entry(tpos, pos, head, member) \for (pos = (head)->first; \     pos && ({ prefetch(pos->next); 1;}) && \({ tpos = hlist_entry(pos, typeof(*tpos), member); 1;}); \     pos = pos->next)/** * hlist_for_each_entry_continue - iterate over a hlist continuing after current point * @tpos:the type * to use as a loop cursor. * @pos:the &struct hlist_node to use as a loop cursor. * @member:the name of the hlist_node within the struct. */#define hlist_for_each_entry_continue(tpos, pos, member) \for (pos = (pos)->next; \     pos && ({ prefetch(pos->next); 1;}) && \({ tpos = hlist_entry(pos, typeof(*tpos), member); 1;}); \     pos = pos->next)/** * hlist_for_each_entry_from - iterate over a hlist continuing from current point * @tpos:the type * to use as a loop cursor. * @pos:the &struct hlist_node to use as a loop cursor. * @member:the name of the hlist_node within the struct. */#define hlist_for_each_entry_from(tpos, pos, member) \for (; pos && ({ prefetch(pos->next); 1;}) && \({ tpos = hlist_entry(pos, typeof(*tpos), member); 1;}); \     pos = pos->next)/** * hlist_for_each_entry_safe - iterate over list of given type safe against removal of list entry * @tpos:the type * to use as a loop cursor. * @pos:the &struct hlist_node to use as a loop cursor. * @n:another &struct hlist_node to use as temporary storage * @head:the head for your list. * @member:the name of the hlist_node within the struct. */#define hlist_for_each_entry_safe(tpos, pos, n, head, member)  \for (pos = (head)->first; \     pos && ({ n = pos->next; 1; }) &&  \({ tpos = hlist_entry(pos, typeof(*tpos), member); 1;}); \     pos = n)#endif