這是在Linux下面最常用的一個統一的鏈表結構，Linux就是用這個結構將所有的Driver、Device什么的都分別串在一起。我覺得寫得非常好，大家來看一看。

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#ifndef _LINUX_LIST_H
#define _LINUX_LIST_H

#ifdef __KERNEL__

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
?* 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
?* 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.
?* Note: list_empty on entry does not return true after this, the entry is in an undefined state.
?*/
static __inline__ void list_del(struct list_head *entry)
{
　　__list_del(entry->prev, entry->next);
}

/**
?* list_del_init - deletes entry from list and reinitialize it.
?*/
static __inline__ void list_del_init(struct list_head *entry)
{
　　__list_del(entry->prev, entry->next);
　　INIT_LIST_HEAD(entry);
}

/*
?* list_empty - tests whether a list is empty
?*/
static __inline__ int list_empty(struct list_head *head)
{
　　return head->next == head;
}

/**
?* 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)
{
　　struct list_head *first = list->next;

　　?if (first != list) {
　　　　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_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) \
　　((type *)((char *)(ptr)-(unsigned long)(&((type *)0)->member)))

/**
?* list_for_each?-?iterate over a list
?* @pos:?the &struct list_head to use as a loop counter.
?* @head:?the head for your list.
?*/
#define list_for_each(pos, head) \
　　for (pos = (head)->next; pos != (head); pos = pos->next)

#endif /* __KERNEL__ */

#endif

補充一下——給看不懂的同志。

它是個雙向的循環鏈表，這個鏈表可以用到任何結構里，比如：

struct kk {
　　type1 data1;
　　type2 data2;
　　......
　　struct list_head list;
　　typen datan;
}

再有一個鏈表頭：LIST_HEAD(kk_list)

然后調用鏈表函數的時候是這樣的，比如要把一個新結點kk_node加到鏈表尾

list_add_tail ( &(kk_node.list), &kk_list );

只是把結點中的list成員加進去，要獲得某個包含list_head節點的結構指針

struct kk *p = list_entry( p, kk, list );

當調用delete操作時，僅僅是把結點從鏈表中去掉，并不真正釋放結點所占用的空間，因為這是個通用結構嘛，分配釋放由用戶自己管理。

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