在用户空间编程使用linux内核链表list，hlist宏定义和操作
http://www.chinaunix.net 作者:思一克 发表于：2008-09-17 09:56:44
【发表评论】【查看原文】【C/C++讨论区】【关闭】
在用户空间编程使用linux内核链表list，hlist宏定义和操作.
linux内核中的list_head和hlist_head/hlist_node是将数据结构串起来成为链表的两个重要链表构造工具。利用他们和其对应的宏定义，可以非常容易地将数据构成链表，进行链表的各种操作，和数据查询。
在内核中，他们使用的十分广泛。这些链表操作宏定义具有通用性，和具体数据结构无关。
利用他们，编程者就不必要自己具体操作链表的指针，而集中精力关心数据本身。使用这些工具的程序效率是很高的。
因为他们是内核定义的数据结构，在内核编程使用起来十分简单。
struct list_head { struct list_head *prev, *next; } 尺寸为2个指针大小。32位系统上为8个字节。
struct hlist_node 也是包含2个指针占8个字节。
struct hlist_head 占4个字节.
用他们将多个相同的数据结构串起来，必须在数据结构中加上他们的定义。一个数据结构也可以用多个相同链表或不同链表同时串起，串到多个不同的串中。
如果不在内核而在用户空间编程，也可以利用这些链表。（事实上，内核其它的数据结构多数都可以在用户空间使用）。
要“移植到用户空间”， 必须查找定义链表数据和宏的包含文件，将该文件拷贝出来，做适当改动，去掉内核特定的定义开关。如果该文件中引用的其它内核包含文件的关键数据定义，最好去掉引用，而将定义拷贝过来。
下面我给出的例子，就是一个用不同list_head和hash list将用户数据struct ST同时串起来的例子。
i_list是普通list的串。
i_hash是hash list的串（实际是多个串，被HASH分散在数组中,HASH关键字即是数组下标）
你可以想象数据结构是一个个货场的相同型号的分散放置的集装箱，为了将他们串起来，必须在箱子上安装上有孔的铁环，然后用铁丝通过这些安装上铁环就可以将他们串起来。
数据结构中的定义struct list_head就相当于铁环，可以焊接到箱子的任何位置。头部中间尾部都可以。
本例子中，一个箱子上安装了2个环，一个是i_list, 将箱子用一个长铁丝全部穿起来的。
还安了一个环i_hash, 这个环的用途是将箱子分组串到不同的串中（每个串使用一个独立的铁丝，当然每根铁丝长度就短了）。不同串的各个铁丝的头部排列放到一个hlist_head的数组中。
为了查找一个箱子，可以顺着长铁丝找（遍历），一个一个比较，知道找到箱子。但这样慢。
还可以直接顺着某个短铁丝找，如果事先可以确定要找的箱子必定在该端铁丝串中－－这是可以做到的,hash的作用。
struct hlist_head仅仅用了一个指针，占4个字节，因为hash数组往往相当大，而每个串长度很短（hash的目的）。这样可以节省4个字节乘以数据大小的空间。
文件list.h是 include/linux/list.h文件的用户空间改编版本。
具体的定义的含义，我这里不再叙述，你可以自己查找。有许多内核数据结构分析的地方有解释。
建议用户用C编程时候，如涉及到链表使用，那么使用list_head! 可以极大节省你的工作量和调式时间。
linux内核中还有许多定义好通用的东西，都是非常精彩和高效的。许多都可移植到用户程序中使用。
[CODE]
#include <stdio.h>
#include <stdlib.h>
#include "list.h"
struct ST {
unsigned char ch;
int this_data;
struct list_head i_list;
int more_data;
struct hlist_node i_hash;
char str_data[32];
//.......
int end_data;
} *st;
struct list_head list1;
struct hlist_head hlist[1024];
#define LISTSIZE 1024
unsigned int gethash(int c)
{
return (c & 0xff);
}
main()
{
int i;
unsigned int hash;
struct list_head *list;
struct list_head *n, *p;
struct ST *pst;
struct hlist_node *hp;
INIT_LIST_HEAD(&list1);
for(hash = 0; hash < LISTSIZE; hash++)
INIT_HLIST_HEAD(&hlist[hash]);
for(i = 0; i < LISTSIZE; i++) {
struct ST *p = malloc(sizeof(*p));
if(!p) {
printf("malloc.\n");
break;
}
p->ch = 'a' + i;
//串入长串
list_add(&p->i_list, &list1);
//串入HASH短串
hash = gethash(p->ch);
printf("ALLOC %x %d %p %u\n", p->ch, i, p, hash);
hlist_add_head(&p->i_hash, &hlist[hash]);
}
//通过长铁丝遍历
i = 0;
list_for_each(list, &list1) {
struct ST *p = list_entry(list, struct ST, i_list);
printf("%p value %d = %c\n", p, i, p->ch);
i++;
}
printf("total %d \n", i);
//----------------------
//通过hash串查找内容'C'的箱子
hash = gethash('c');
hlist_for_each(hp, &hlist[hash]) {
struct ST *p = hlist_entry(hp, struct ST, i_hash);
printf("hlist: %c\n", p->ch);
}
}
[/CODE]
改编后的放在用户空间的头文件list.h
[CODE]
#ifndef _LINUX_LIST_H
#define _LINUX_LIST_H
#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) ); } )
static inline void prefetch(const void *x) {;}
static inline void prefetchw(const void *x) {;}
#define LIST_POISON1 ((void *) 0x00100100)
#define LIST_POISON2 ((void *) 0x00200200)
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)
#define INIT_LIST_HEAD(ptr) do { \
(ptr)->next = (ptr); (ptr)->prev = (ptr); \
} while (0)
/*
* 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 - 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);
}
static inline void __list_del(struct list_head * prev, struct list_head * next)
{
next->prev = prev;
prev->next = next;
}
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 void list_del_init(struct list_head *entry)
{
__list_del(entry->prev, entry->next);
INIT_LIST_HEAD(entry);
}
static inline void list_move(struct list_head *list, struct list_head *head)
{
__list_del(list->prev, list->next);
list_add(list, head);
}
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);
}
static inline int list_empty(const struct list_head *head)
{
return head->next == head;
}
static inline int list_empty_careful(const struct list_head *head)
{
struct list_head *next = head->next;
return (next == head) && (next == head->prev);
}
static inline void __list_splice(struct list_head *list,
struct list_head *head)
{
struct list_head *first = list->next;
struct list_head *last = list->prev;
struct list_head *at = head->next;
first->prev = head;
head->next = first;
last->next = at;
at->prev = last;
}
/**
* list_splice - join two lists
* @list: the new list to add.
* @head: the place to add it in the first list.
*/
static inline void list_splice(struct list_head *list, struct list_head *head)
{
if (!list_empty(list))
__list_splice(list, 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);
INIT_LIST_HEAD(list);
}
}
#define list_entry(ptr, type, member) container_of(ptr, type, member)
#define list_for_each(pos, head) \
for (pos = (head)->next; prefetch(pos->next), pos != (head); \
pos = pos->next)
#define __list_for_each(pos, head) \
for (pos = (head)->next; pos != (head); pos = pos->next)
#define list_for_each_prev(pos, head) \
for (pos = (head)->prev; prefetch(pos->prev), pos != (head); \
pos = pos->prev)
#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); \
prefetch(pos->member.next), &pos->member != (head); \
pos = list_entry(pos->member.next, typeof(*pos), member))
#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))
#define list_prepare_entry(pos, head, member) \
((pos) ? : list_entry(head, typeof(*pos), member))
#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))
#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))
//HASH LIST
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)
#define INIT_HLIST_NODE(ptr) ((ptr)->next = NULL, (ptr)->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 (n->pprev) {
__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;
}
#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)
#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)
#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)
#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)
#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
[/CODE]
W.Z.T 回复于：2007-05-27 16:28:40
加精...
flw2 回复于：2007-05-27 19:04:46
版主自己加个精华好了
一直觉得这个东东和内核还是用户空间基本没有区别。
福瑞哈哥 回复于：2007-05-27 20:17:57
記得以前有一個全macro的list.h和rbtree.h，可惜現在找不到了。
acguy 回复于：2007-05-28 12:52:41
如果用c++还是stl方便
思一克 回复于：2007-05-28 13:08:23
STL的效率你实验过？
xhl 回复于：2007-05-28 14:49:00
引用：原帖由 福瑞哈哥 于 2007-5-27 20:17 发表
記得以前有一個全macro的list.h和rbtree.h，可惜現在找不到了。
我喜欢用BSD 的 queue.h tree.h 等，
虽然全是macro写的，调试不太方便，但总比自己写省心。
[ 本帖最后由 xhl 于 2007-5-28 14:50 编辑 ]
福瑞哈哥 回复于：2007-05-28 15:11:53
引用：原帖由 xhl 于 2007-5-28 14:49 发表
我喜欢用BSD 的 queue.h tree.h 等，
虽然全是macro写的，调试不太方便，但总比自己写省心。
記起來了。
duanjigang 回复于：2007-05-28 15:32:05
以前也尝试过这么写过，不过最后发现初始化和繁杂的参数实在令人烦恼，干脆就改用C++风格了
STL还是不错
flw2 回复于：2007-05-28 18:48:43
引用：原帖由 duanjigang 于 2007-5-28 15:32 发表
以前也尝试过这么写过，不过最后发现初始化和繁杂的参数实在令人烦恼，干脆就改用C++风格了
STL还是不错
c能用stl吗?
DesignInside 回复于：2007-05-28 20:43:05
wow...good job
duanjigang 回复于：2007-05-29 09:16:07
引用：原帖由 flw2 于 2007-5-28 18:48 发表
c能用stl吗?
:em06::em06::em06:
我当然是用C++咯。。。。
思一克 回复于：2007-05-29 09:34:29
KERNEL中主要是效率（速度），麻烦些不怕。一些系统软件也是如此。
C++/STL不容易作到。
converse 回复于：2008-04-11 14:34:37
才看到思兄这份代码,我最近也要研究一下linux里面的这些宏,不过用g++编译的时候会报一些错误,虽然用C++的人使用这种宏的可能性不大,不过还是尽量做的完美一些好了,我做了一些修改:
#ifndef _LINUX_LIST_H
#define _LINUX_LIST_H
#ifdef __cplusplus
extern "C" {
#endif /* __cplusplus */
#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) ); } )
static inline void prefetch(const void *x) {;}
static inline void prefetchw(const void *x) {;}
#define LIST_POISON1 ((void *) 0x00100100)
#define LIST_POISON2 ((void *) 0x00200200)
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)
#define INIT_LIST_HEAD(ptr) do { \
(ptr)->next = (ptr); (ptr)->prev = (ptr); \
} while (0)
/*
* * Insert a newobj 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 *newobj,
struct list_head *prev,
struct list_head *next)
{
next->prev = newobj;
newobj->next = next;
newobj->prev = prev;
prev->next = newobj;
}
/**
* * list_add - add a newobj entry
* * @newobj: newobj entry to be added
* * @head: list head to add it after
* *
* * Insert a newobj entry after the specified head.
* * This is good for implementing stacks.
* */
static inline void list_add(struct list_head *newobj, struct list_head *head)
{
__list_add(newobj, head, head->next);
}
/**
* * list_add_tail - add a newobj entry
* * @newobj: newobj entry to be added
* * @head: list head to add it before
* *
* * Insert a newobj entry before the specified head.
* * This is useful for implementing queues.
* */
static inline void list_add_tail(struct list_head *newobj, struct list_head *head)
{
__list_add(newobj, head->prev, head);
}
static inline void __list_del(struct list_head * prev, struct list_head * next)
{
next->prev = prev;
prev->next = next;
}
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;
}
static inline void list_del_init(struct list_head *entry)
{
__list_del(entry->prev, entry->next);
INIT_LIST_HEAD(entry);
}
static inline void list_move(struct list_head *list, struct list_head *head)
{
__list_del(list->prev, list->next);
list_add(list, head);
}
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);
}
static inline int list_empty(const struct list_head *head)
{
return head->next == head;
}
static inline int list_empty_careful(const struct list_head *head)
{
struct list_head *next = head->next;
return (next == head) && (next == head->prev);
}
static inline void __list_splice(struct list_head *list,
struct list_head *head)
{
struct list_head *first = list->next;
struct list_head *last = list->prev;
struct list_head *at = head->next;
first->prev = head;
head->next = first;
last->next = at;
at->prev = last;
}
/**
* * list_splice - join two lists
* * @list: the newobj list to add.
* * @head: the place to add it in the first list.
* */
static inline void list_splice(struct list_head *list, struct list_head *head)
{
if (!list_empty(list))
__list_splice(list, head);
}
/**
* * list_splice_init - join two lists and reinitialise the emptied list.
* * @list: the newobj 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);
INIT_LIST_HEAD(list);
}
}
#define list_entry(ptr, type, member) container_of(ptr, type, member)
#define list_for_each(pos, head) \
for (pos = (head)->next; prefetch(pos->next), pos != (head); \
pos = pos->next)
#define __list_for_each(pos, head) \
for (pos = (head)->next; pos != (head); pos = pos->next)
#define list_for_each_prev(pos, head) \
for (pos = (head)->prev; prefetch(pos->prev), pos != (head); \
pos = pos->prev)
#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); \
prefetch(pos->member.next), &pos->member != (head); \
pos = list_entry(pos->member.next, typeof(*pos), member))
#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))
#define list_prepare_entry(pos, head, member) \
((pos) ? : list_entry(head, typeof(*pos), member))
#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))
#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))
//HASH LIST
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)
#define INIT_HLIST_NODE(ptr) ((ptr)->next = NULL, (ptr)->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 = (struct hlist_node*)LIST_POISON1;
n->pprev = (struct hlist_node**)LIST_POISON2;
}
static inline void hlist_del_init(struct hlist_node *n)
{
if (n->pprev) {
__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;
}
#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)
#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)
#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)
#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)
#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)
#ifdef __cplusplus
}
#endif /* __cplusplus */
#endif
芙蓉 回复于：2008-04-11 14:47:27
:mrgreen: :mrgreen: :mrgreen:
converse 回复于：2008-04-11 15:49:46
看了一下 这些宏的设计很巧妙 但是用了一些gcc的扩展 比如typeof 这样要移植到别的编译器可能有一些问题 折中的办法是使用者自己传入类型替代这个宏.
converse 回复于：2008-04-11 15:53:59
比如container_of宏的改造:
从
#define container_of(ptr, type, member) ( { \
const typeof( ((type *)0)->member ) *__mptr = (ptr); \
(type *)( (char *)__mptr - offsetof(type,member) ); } )
变为:
#define container_of2(ptr, ptrtype, type, member) ( { \
const ptrtype *__mptr = (ptr); \
(type *)( (char *)__mptr - offsetof(type,member) ); } )
思一克 回复于：2008-04-11 16:21:12
LINUX代码非常巧妙, 还有许多比如树操作, 也是类似的宏+代码, 也可以在应用程序中使用.
引用：原帖由 converse 于 2008-4-11 15:53 发表 [url=http://bbs.chinaunix.net/redirect.php?goto=findpost&pid=8201216&ptid=941100]
比如container_of宏的改造:
从
#define container_of(ptr, type, member) ( { \
const typeof( ((type *)0)->member ) *__mptr = (ptr); \
(type *)( (char *)__mptr - offsetof(type,memb ...
芙蓉 回复于：2008-04-11 17:16:38
引用：原帖由 converse 于 2008-4-11 15:53 发表 [url=http://bbs.chinaunix.net/redirect.php?goto=findpost&pid=8201216&ptid=941100]
比如container_of宏的改造:
从
#define container_of(ptr, type, member) ( { \
const typeof( ((type *)0)->member ) *__mptr = (ptr); \
(type *)( (char *)__mptr - offsetof(type,memb ...
为什么不变为：
#define container_of2(ptr, type, member) ( { \
(type *)( (char *)(ptr) - offsetof(type,member) ); } )
上面的代码，该用typeof定义变量的时候不用，比如list_for_each_entry里的head
不该用typeof的时候却用了，比如这个container_of
cobranail 回复于：2008-05-10 18:38:43
这个list.h在非linux系统中使用不会有问题吧？
#define LIST_POISON1 ((void *) 0x00100100)
#define LIST_POISON2 ((void *) 0x00200200)
这两个定义的作用是什么呢？
pilgrim_kevin 回复于：2008-09-17 09:56:44
学习。
原文链接：http://bbs.chinaunix.net/viewthread.php?tid=941100
转载请注明作者名及原文出处
【发表评论】【查看原文】【C/C++讨论区】【关闭】
在用户空间编程使用linux内核链表list，hlist宏定义和操作.
linux内核中的list_head和hlist_head/hlist_node是将数据结构串起来成为链表的两个重要链表构造工具。利用他们和其对应的宏定义，可以非常容易地将数据构成链表，进行链表的各种操作，和数据查询。
在内核中，他们使用的十分广泛。这些链表操作宏定义具有通用性，和具体数据结构无关。
利用他们，编程者就不必要自己具体操作链表的指针，而集中精力关心数据本身。使用这些工具的程序效率是很高的。
因为他们是内核定义的数据结构，在内核编程使用起来十分简单。
struct list_head { struct list_head *prev, *next; } 尺寸为2个指针大小。32位系统上为8个字节。
struct hlist_node 也是包含2个指针占8个字节。
struct hlist_head 占4个字节.
用他们将多个相同的数据结构串起来，必须在数据结构中加上他们的定义。一个数据结构也可以用多个相同链表或不同链表同时串起，串到多个不同的串中。
如果不在内核而在用户空间编程，也可以利用这些链表。（事实上，内核其它的数据结构多数都可以在用户空间使用）。
要“移植到用户空间”， 必须查找定义链表数据和宏的包含文件，将该文件拷贝出来，做适当改动，去掉内核特定的定义开关。如果该文件中引用的其它内核包含文件的关键数据定义，最好去掉引用，而将定义拷贝过来。
下面我给出的例子，就是一个用不同list_head和hash list将用户数据struct ST同时串起来的例子。
i_list是普通list的串。
i_hash是hash list的串（实际是多个串，被HASH分散在数组中,HASH关键字即是数组下标）
你可以想象数据结构是一个个货场的相同型号的分散放置的集装箱，为了将他们串起来，必须在箱子上安装上有孔的铁环，然后用铁丝通过这些安装上铁环就可以将他们串起来。
数据结构中的定义struct list_head就相当于铁环，可以焊接到箱子的任何位置。头部中间尾部都可以。
本例子中，一个箱子上安装了2个环，一个是i_list, 将箱子用一个长铁丝全部穿起来的。
还安了一个环i_hash, 这个环的用途是将箱子分组串到不同的串中（每个串使用一个独立的铁丝，当然每根铁丝长度就短了）。不同串的各个铁丝的头部排列放到一个hlist_head的数组中。
为了查找一个箱子，可以顺着长铁丝找（遍历），一个一个比较，知道找到箱子。但这样慢。
还可以直接顺着某个短铁丝找，如果事先可以确定要找的箱子必定在该端铁丝串中－－这是可以做到的,hash的作用。
struct hlist_head仅仅用了一个指针，占4个字节，因为hash数组往往相当大，而每个串长度很短（hash的目的）。这样可以节省4个字节乘以数据大小的空间。
文件list.h是 include/linux/list.h文件的用户空间改编版本。
具体的定义的含义，我这里不再叙述，你可以自己查找。有许多内核数据结构分析的地方有解释。
建议用户用C编程时候，如涉及到链表使用，那么使用list_head! 可以极大节省你的工作量和调式时间。
linux内核中还有许多定义好通用的东西，都是非常精彩和高效的。许多都可移植到用户程序中使用。
[CODE]
#include <stdio.h>
#include <stdlib.h>
#include "list.h"
struct ST {
unsigned char ch;
int this_data;
struct list_head i_list;
int more_data;
struct hlist_node i_hash;
char str_data[32];
//.......
int end_data;
} *st;
struct list_head list1;
struct hlist_head hlist[1024];
#define LISTSIZE 1024
unsigned int gethash(int c)
{
return (c & 0xff);
}
main()
{
int i;
unsigned int hash;
struct list_head *list;
struct list_head *n, *p;
struct ST *pst;
struct hlist_node *hp;
INIT_LIST_HEAD(&list1);
for(hash = 0; hash < LISTSIZE; hash++)
INIT_HLIST_HEAD(&hlist[hash]);
for(i = 0; i < LISTSIZE; i++) {
struct ST *p = malloc(sizeof(*p));
if(!p) {
printf("malloc.\n");
break;
}
p->ch = 'a' + i;
//串入长串
list_add(&p->i_list, &list1);
//串入HASH短串
hash = gethash(p->ch);
printf("ALLOC %x %d %p %u\n", p->ch, i, p, hash);
hlist_add_head(&p->i_hash, &hlist[hash]);
}
//通过长铁丝遍历
i = 0;
list_for_each(list, &list1) {
struct ST *p = list_entry(list, struct ST, i_list);
printf("%p value %d = %c\n", p, i, p->ch);
i++;
}
printf("total %d \n", i);
//----------------------
//通过hash串查找内容'C'的箱子
hash = gethash('c');
hlist_for_each(hp, &hlist[hash]) {
struct ST *p = hlist_entry(hp, struct ST, i_hash);
printf("hlist: %c\n", p->ch);
}
}
[/CODE]
改编后的放在用户空间的头文件list.h
[CODE]
#ifndef _LINUX_LIST_H
#define _LINUX_LIST_H
#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) ); } )
static inline void prefetch(const void *x) {;}
static inline void prefetchw(const void *x) {;}
#define LIST_POISON1 ((void *) 0x00100100)
#define LIST_POISON2 ((void *) 0x00200200)
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)
#define INIT_LIST_HEAD(ptr) do { \
(ptr)->next = (ptr); (ptr)->prev = (ptr); \
} while (0)
/*
* 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 - 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);
}
static inline void __list_del(struct list_head * prev, struct list_head * next)
{
next->prev = prev;
prev->next = next;
}
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 void list_del_init(struct list_head *entry)
{
__list_del(entry->prev, entry->next);
INIT_LIST_HEAD(entry);
}
static inline void list_move(struct list_head *list, struct list_head *head)
{
__list_del(list->prev, list->next);
list_add(list, head);
}
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);
}
static inline int list_empty(const struct list_head *head)
{
return head->next == head;
}
static inline int list_empty_careful(const struct list_head *head)
{
struct list_head *next = head->next;
return (next == head) && (next == head->prev);
}
static inline void __list_splice(struct list_head *list,
struct list_head *head)
{
struct list_head *first = list->next;
struct list_head *last = list->prev;
struct list_head *at = head->next;
first->prev = head;
head->next = first;
last->next = at;
at->prev = last;
}
/**
* list_splice - join two lists
* @list: the new list to add.
* @head: the place to add it in the first list.
*/
static inline void list_splice(struct list_head *list, struct list_head *head)
{
if (!list_empty(list))
__list_splice(list, 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);
INIT_LIST_HEAD(list);
}
}
#define list_entry(ptr, type, member) container_of(ptr, type, member)
#define list_for_each(pos, head) \
for (pos = (head)->next; prefetch(pos->next), pos != (head); \
pos = pos->next)
#define __list_for_each(pos, head) \
for (pos = (head)->next; pos != (head); pos = pos->next)
#define list_for_each_prev(pos, head) \
for (pos = (head)->prev; prefetch(pos->prev), pos != (head); \
pos = pos->prev)
#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); \
prefetch(pos->member.next), &pos->member != (head); \
pos = list_entry(pos->member.next, typeof(*pos), member))
#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))
#define list_prepare_entry(pos, head, member) \
((pos) ? : list_entry(head, typeof(*pos), member))
#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))
#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))
//HASH LIST
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)
#define INIT_HLIST_NODE(ptr) ((ptr)->next = NULL, (ptr)->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 (n->pprev) {
__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;
}
#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)
#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)
#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)
#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)
#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
[/CODE]
W.Z.T 回复于：2007-05-27 16:28:40
加精...
flw2 回复于：2007-05-27 19:04:46
版主自己加个精华好了
一直觉得这个东东和内核还是用户空间基本没有区别。
福瑞哈哥 回复于：2007-05-27 20:17:57
記得以前有一個全macro的list.h和rbtree.h，可惜現在找不到了。
acguy 回复于：2007-05-28 12:52:41
如果用c++还是stl方便
思一克 回复于：2007-05-28 13:08:23
STL的效率你实验过？
xhl 回复于：2007-05-28 14:49:00
引用：原帖由 福瑞哈哥 于 2007-5-27 20:17 发表
記得以前有一個全macro的list.h和rbtree.h，可惜現在找不到了。
我喜欢用BSD 的 queue.h tree.h 等，
虽然全是macro写的，调试不太方便，但总比自己写省心。
[ 本帖最后由 xhl 于 2007-5-28 14:50 编辑 ]
福瑞哈哥 回复于：2007-05-28 15:11:53
引用：原帖由 xhl 于 2007-5-28 14:49 发表
我喜欢用BSD 的 queue.h tree.h 等，
虽然全是macro写的，调试不太方便，但总比自己写省心。
記起來了。
duanjigang 回复于：2007-05-28 15:32:05
以前也尝试过这么写过，不过最后发现初始化和繁杂的参数实在令人烦恼，干脆就改用C++风格了
STL还是不错
flw2 回复于：2007-05-28 18:48:43
引用：原帖由 duanjigang 于 2007-5-28 15:32 发表
以前也尝试过这么写过，不过最后发现初始化和繁杂的参数实在令人烦恼，干脆就改用C++风格了
STL还是不错
c能用stl吗?
DesignInside 回复于：2007-05-28 20:43:05
wow...good job
duanjigang 回复于：2007-05-29 09:16:07
引用：原帖由 flw2 于 2007-5-28 18:48 发表
c能用stl吗?
:em06::em06::em06:
我当然是用C++咯。。。。
思一克 回复于：2007-05-29 09:34:29
KERNEL中主要是效率（速度），麻烦些不怕。一些系统软件也是如此。
C++/STL不容易作到。
converse 回复于：2008-04-11 14:34:37
才看到思兄这份代码,我最近也要研究一下linux里面的这些宏,不过用g++编译的时候会报一些错误,虽然用C++的人使用这种宏的可能性不大,不过还是尽量做的完美一些好了,我做了一些修改:
#ifndef _LINUX_LIST_H
#define _LINUX_LIST_H
#ifdef __cplusplus
extern "C" {
#endif /* __cplusplus */
#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) ); } )
static inline void prefetch(const void *x) {;}
static inline void prefetchw(const void *x) {;}
#define LIST_POISON1 ((void *) 0x00100100)
#define LIST_POISON2 ((void *) 0x00200200)
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)
#define INIT_LIST_HEAD(ptr) do { \
(ptr)->next = (ptr); (ptr)->prev = (ptr); \
} while (0)
/*
* * Insert a newobj 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 *newobj,
struct list_head *prev,
struct list_head *next)
{
next->prev = newobj;
newobj->next = next;
newobj->prev = prev;
prev->next = newobj;
}
/**
* * list_add - add a newobj entry
* * @newobj: newobj entry to be added
* * @head: list head to add it after
* *
* * Insert a newobj entry after the specified head.
* * This is good for implementing stacks.
* */
static inline void list_add(struct list_head *newobj, struct list_head *head)
{
__list_add(newobj, head, head->next);
}
/**
* * list_add_tail - add a newobj entry
* * @newobj: newobj entry to be added
* * @head: list head to add it before
* *
* * Insert a newobj entry before the specified head.
* * This is useful for implementing queues.
* */
static inline void list_add_tail(struct list_head *newobj, struct list_head *head)
{
__list_add(newobj, head->prev, head);
}
static inline void __list_del(struct list_head * prev, struct list_head * next)
{
next->prev = prev;
prev->next = next;
}
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;
}
static inline void list_del_init(struct list_head *entry)
{
__list_del(entry->prev, entry->next);
INIT_LIST_HEAD(entry);
}
static inline void list_move(struct list_head *list, struct list_head *head)
{
__list_del(list->prev, list->next);
list_add(list, head);
}
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);
}
static inline int list_empty(const struct list_head *head)
{
return head->next == head;
}
static inline int list_empty_careful(const struct list_head *head)
{
struct list_head *next = head->next;
return (next == head) && (next == head->prev);
}
static inline void __list_splice(struct list_head *list,
struct list_head *head)
{
struct list_head *first = list->next;
struct list_head *last = list->prev;
struct list_head *at = head->next;
first->prev = head;
head->next = first;
last->next = at;
at->prev = last;
}
/**
* * list_splice - join two lists
* * @list: the newobj list to add.
* * @head: the place to add it in the first list.
* */
static inline void list_splice(struct list_head *list, struct list_head *head)
{
if (!list_empty(list))
__list_splice(list, head);
}
/**
* * list_splice_init - join two lists and reinitialise the emptied list.
* * @list: the newobj 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);
INIT_LIST_HEAD(list);
}
}
#define list_entry(ptr, type, member) container_of(ptr, type, member)
#define list_for_each(pos, head) \
for (pos = (head)->next; prefetch(pos->next), pos != (head); \
pos = pos->next)
#define __list_for_each(pos, head) \
for (pos = (head)->next; pos != (head); pos = pos->next)
#define list_for_each_prev(pos, head) \
for (pos = (head)->prev; prefetch(pos->prev), pos != (head); \
pos = pos->prev)
#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); \
prefetch(pos->member.next), &pos->member != (head); \
pos = list_entry(pos->member.next, typeof(*pos), member))
#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))
#define list_prepare_entry(pos, head, member) \
((pos) ? : list_entry(head, typeof(*pos), member))
#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))
#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))
//HASH LIST
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)
#define INIT_HLIST_NODE(ptr) ((ptr)->next = NULL, (ptr)->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 = (struct hlist_node*)LIST_POISON1;
n->pprev = (struct hlist_node**)LIST_POISON2;
}
static inline void hlist_del_init(struct hlist_node *n)
{
if (n->pprev) {
__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;
}
#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)
#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)
#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)
#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)
#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)
#ifdef __cplusplus
}
#endif /* __cplusplus */
#endif
芙蓉 回复于：2008-04-11 14:47:27
:mrgreen: :mrgreen: :mrgreen:
converse 回复于：2008-04-11 15:49:46
看了一下 这些宏的设计很巧妙 但是用了一些gcc的扩展 比如typeof 这样要移植到别的编译器可能有一些问题 折中的办法是使用者自己传入类型替代这个宏.
converse 回复于：2008-04-11 15:53:59
比如container_of宏的改造:
从
#define container_of(ptr, type, member) ( { \
const typeof( ((type *)0)->member ) *__mptr = (ptr); \
(type *)( (char *)__mptr - offsetof(type,member) ); } )
变为:
#define container_of2(ptr, ptrtype, type, member) ( { \
const ptrtype *__mptr = (ptr); \
(type *)( (char *)__mptr - offsetof(type,member) ); } )
思一克 回复于：2008-04-11 16:21:12
LINUX代码非常巧妙, 还有许多比如树操作, 也是类似的宏+代码, 也可以在应用程序中使用.
引用：原帖由 converse 于 2008-4-11 15:53 发表 [url=http://bbs.chinaunix.net/redirect.php?goto=findpost&pid=8201216&ptid=941100]
比如container_of宏的改造:
从
#define container_of(ptr, type, member) ( { \
const typeof( ((type *)0)->member ) *__mptr = (ptr); \
(type *)( (char *)__mptr - offsetof(type,memb ...
芙蓉 回复于：2008-04-11 17:16:38
引用：原帖由 converse 于 2008-4-11 15:53 发表 [url=http://bbs.chinaunix.net/redirect.php?goto=findpost&pid=8201216&ptid=941100]
比如container_of宏的改造:
从
#define container_of(ptr, type, member) ( { \
const typeof( ((type *)0)->member ) *__mptr = (ptr); \
(type *)( (char *)__mptr - offsetof(type,memb ...
为什么不变为：
#define container_of2(ptr, type, member) ( { \
(type *)( (char *)(ptr) - offsetof(type,member) ); } )
上面的代码，该用typeof定义变量的时候不用，比如list_for_each_entry里的head
不该用typeof的时候却用了，比如这个container_of
cobranail 回复于：2008-05-10 18:38:43
这个list.h在非linux系统中使用不会有问题吧？
#define LIST_POISON1 ((void *) 0x00100100)
#define LIST_POISON2 ((void *) 0x00200200)
这两个定义的作用是什么呢？
pilgrim_kevin 回复于：2008-09-17 09:56:44
学习。
原文链接：http://bbs.chinaunix.net/viewthread.php?tid=941100
转载请注明作者名及原文出处