Linux2.6.32内核笔记（5）在应用程序中移植使用内核链表
2015-09-12 11:47
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摘要：将内核链表移植到应用程序中，实现创建，添加节点，遍历，删除的操作。
首先复习一下内核链表中经常使用的几个函数，在/include/linux/list.h中。
创建链表：
插入节点：
删除节点：
遍历链表：
取出节点：
移植过程中用到的其他函数：
1.malloc
函数原型：extern void *malloc(unsigned int num_bytes);
功能：分配字节长度为num_bytes内存，如果成功则返回指向内存起始地址的指针，否则返回null。
说明：这里声明为void *表示未确定类型的指针，这样使用的时候就可以强制转换为其他我们需要的任何类型的指针。
2.memset
函数原型：void *memset(void *s,int ch,seze_t n);
功能：将s指向的某一块内存中的前n个字节的内容全部填充为ch。一般用来对新申请的内存做初始化工作，ch一般都是填充0。我们在使用较大的结构体和数组的时候，都会使用其对分配到的内存清零。
3.sprintf
函数原型：int sprintf(char *buffer,const char *format，[arugument]…);
功能：把格式化的数据写入某个字符串中，返回值是字符串的长度。
移植步骤：
1.创建list.h
因为我们要写成一个app，里面用到很多内核链表的函数，都在list.h里面声明的，一开始这里我就偷懒把内核里面的list.h拷贝一份，放到我当前的工作目录下，命名为list.h，后来编译的时候提示找不到list.h里面加进去的那三个头文件，于是我又把position.h,这三个头文件注释掉了，但是提示LIST_POSITION1和LIST_POSITION2没有定义还有别的错误，于是利用grep查找，到源码目录下，把这部分拷贝到我们的list.h前面部分里面来就可以了。完整的list.c附在最后。
2.创建listapp.c添加头文件
这里我命名为listapp.c，因为我们要用到很多头文件，这里都添加进去，我添加的如下;
3.创建球员信息结构体
4.main函数
主要思想是创建链表，分配内存，插入节点，遍历输出，删除节点。
编译成功后运行出现如下信息;
可以看到我们的链表操作是成功了，输出信息也与期望值一样，但是最后free的时候出现了core dump，这个问题查了下有几种解释，这里大概是数组操作越界，或者我们修改了mem区的指针信息，导致free释放内存的时候，释放到别的地方去了，这里不做深究了，留待之后结局。
最后附上list.h和listapp.c的代码，结束，如有不正确的地方还请指出，大家共同进步。
list.h如下
listapp.c如下
首先复习一下内核链表中经常使用的几个函数，在/include/linux/list.h中。
创建链表：
<span style="font-size:18px;">INIT_LIST_HEAD（）
staticinline void INIT_LIST_HEAD(struct list_head *list)
{
list->next = list;
list->prev = list;
}</span>插入节点：
<span style="font-size:18px;">list_add（）在链表头插入
list_add_tail()在链表尾插入
staticinline void list_add(struct list_head *new, struct list_head *head)
{
__list_add(new, head, head->next);
}
staticinline void list_add_tail(struct list_head *new, struct list_head *head)
{
__list_add(new, head->prev, head);
}</span>删除节点：
<span style="font-size:18px;">list_del()
staticinline void list_del(struct list_head *entry)
{
__list_del(entry->prev, entry->next);
entry->next = LIST_POISON1;
entry->prev = LIST_POISON2;
}</span>遍历链表：
<span style="font-size:18px;">list_for_each()
#definelist_for_each(pos, head) \
for(pos = (head)->next; prefetch(pos->next), pos != (head); \
pos = pos->next)</span>取出节点：
<span style="font-size:18px;">list_entry() #definelist_entry(ptr, type, member) \ container_of(ptr,type, member)</span>
移植过程中用到的其他函数：
1.malloc
函数原型：extern void *malloc(unsigned int num_bytes);
功能：分配字节长度为num_bytes内存，如果成功则返回指向内存起始地址的指针，否则返回null。
说明：这里声明为void *表示未确定类型的指针，这样使用的时候就可以强制转换为其他我们需要的任何类型的指针。
2.memset
函数原型：void *memset(void *s,int ch,seze_t n);
功能：将s指向的某一块内存中的前n个字节的内容全部填充为ch。一般用来对新申请的内存做初始化工作，ch一般都是填充0。我们在使用较大的结构体和数组的时候，都会使用其对分配到的内存清零。
3.sprintf
函数原型：int sprintf(char *buffer,const char *format，[arugument]…);
功能：把格式化的数据写入某个字符串中，返回值是字符串的长度。
移植步骤：
1.创建list.h
因为我们要写成一个app，里面用到很多内核链表的函数，都在list.h里面声明的，一开始这里我就偷懒把内核里面的list.h拷贝一份，放到我当前的工作目录下，命名为list.h，后来编译的时候提示找不到list.h里面加进去的那三个头文件，于是我又把position.h,这三个头文件注释掉了，但是提示LIST_POSITION1和LIST_POSITION2没有定义还有别的错误，于是利用grep查找，到源码目录下，把这部分拷贝到我们的list.h前面部分里面来就可以了。完整的list.c附在最后。
<span style="font-size:18px;">#ifndef _LINUX_LIST_H
#define _LINUX_LIST_H
#include <linux/stddef.h>
#ifndef ARCH_HAS_PREFETCH
#define ARCH_HAS_PREFETCH
static inline void prefetch(const void *x){;}
#endif
#define LIST_POISON1 ((void *) 0x0)
#define LIST_POISON2 ((void *) 0x0)
#define container_of(ptr ,type,member)({ \
const typeof( ((type *)0)->member ) *__mptr = (ptr); \
(type *)( (char *)__mptr - offsetof(type,member) );})</span>2.创建listapp.c添加头文件
这里我命名为listapp.c，因为我们要用到很多头文件，这里都添加进去，我添加的如下;
<span style="font-size:18px;">#include"list.h"//内核链表操作函数 #include<malloc.h>//使用malloc分配内存 #include<stdio.h>//sprintf和printf #include<string.h>//memset</span><span style="font-size:14px; font-family: Arial, Helvetica, sans-serif; background-color: rgb(255, 255, 255);"> </span>
3.创建球员信息结构体
<span style="font-size:18px;"> structmember
{
charname[10];
intnum;
intscore;
intassists;
structlist_head list;
};</span>4.main函数
主要思想是创建链表，分配内存，插入节点，遍历输出，删除节点。
编译成功后运行出现如下信息;
可以看到我们的链表操作是成功了，输出信息也与期望值一样，但是最后free的时候出现了core dump，这个问题查了下有几种解释，这里大概是数组操作越界，或者我们修改了mem区的指针信息，导致free释放内存的时候，释放到别的地方去了，这里不做深究了，留待之后结局。
最后附上list.h和listapp.c的代码，结束，如有不正确的地方还请指出，大家共同进步。
list.h如下
<span style="font-size:14px;">#ifndef _LINUX_LIST_H
#define _LINUX_LIST_H
#include <linux/stddef.h>
#ifndef ARCH_HAS_PREFETCH
#define ARCH_HAS_PREFETCH
static inline void prefetch(const void *x) {;}
#endif
#define LIST_POISON1 ((void *) 0x0)
#define LIST_POISON2 ((void *) 0x0)
#define container_of(ptr ,type,member) ({ \
const typeof( ((type *)0)->member ) *__mptr = (ptr); \
(type *)( (char *)__mptr - offsetof(type,member) );})
/*
* 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_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;
}
#else
extern 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_LIST
static inline void list_del(struct list_head *entry)
{
__list_del(entry->prev, entry->next);
entry->next = LIST_POISON1;
entry->prev = LIST_POISON2;
}
#else
extern 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</span>listapp.c如下
<span style="font-size:14px;">#include"list.h"//内核链表操作函数
#include<malloc.h>//使用malloc分配内存
#include<stdio.h>//sprintf和printf
#include<string.h>//memset
struct member
{
char name[100];
int num;
int score;
struct list_head list;
};
struct list_head *pos;//遍历指针的pos，不断地指向链表中节点的指针域，需要是list_head指针类型
struct list_head member_list;//名为menber_list的链表
struct member *tmp;//存放遍历结果，为struct member类型
struct member *pmember;//member的成员
int main(void)
{
unsigned int i = 0; //循环变量的声明
INIT_LIST_HEAD(&member_list); //创建一个链表头，使其前向和后继指针都指向自己，传入参数必须为指针类型，所以取地址
pmember=malloc(sizeof(struct member)*4);
memset(pmember,0,sizeof(struct member)*4);//为member成员分配内存，这里分配四个成员，并且对分配到的内存清零
/*给球员成员命名，编号，进球数*/
sprintf(pmember[1].name,"player %s","xu");
sprintf(pmember[2].name,"player %s","zeng");
sprintf(pmember[3].name,"player %s","le");
sprintf(pmember[4].name,"player %s","suo");
pmember[1].num=9;
pmember[2].num=21;
pmember[3].num=10;
pmember[4].num=66;
pmember[1].score=2;
pmember[2].score=0;
pmember[3].score=1;
pmember[4].score=5;
/*插入节点，list_add第一个参数是成员内部list的指针，第二个是刚才创建的链表头，这样就插入进去了*/
for(i=0;i<4;i++)
{
list_add(&(pmember[i+1].list),&member_list);
printf("###num %d player add sucess!###\n",i+1);
}
/*遍历链表，并开始输出球员信息*/
printf("###start list_for_each player information###\n");
list_for_each(pos,&member_list)
{
tmp=list_entry(pos,struct member,list);//第一个参数为pos，第二个要给进去我们定义的球员信息结构体，最后是结构内部的list名
printf("play %d name %s score %d\n",tmp->num,tmp->name,tmp->score);
}
/*最后删除节点*/
for(i=0;i<4;i++)
{
list_del(&(pmember[i+1].list));
printf("### num %d has deleted###\n",i+1);
}
/*释放分配得内存*/
free(pmember);
}
</span>
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