linux核心學習中–“list.h”中 插入add函數 總結

第一  聲明和初始化，我在這裡不詳細說明了，請看我上一篇博文，在這裡貼出相應的代碼：

#ifndef _LINUX_LIST_H#define _LINUX_LIST_H#define offsetof1(TYPE, MEMBER) ((size_t) &((TYPE *)0)->MEMBER)#define container_of(ptr, type, member) ( { \        const typeof( ((type *)0)->member ) *__mptr = (ptr); \        (type *)( (char *)__mptr - offsetof1(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)#define LIST_POISON1  0#define LIST_POISON2  0struct list_head {        struct list_head *next, *prev;        //雙向鏈表};#define LIST_HEAD_INIT(name) { &(name), &(name) }   //用同一對象初始化next 和prev.#define LIST_HEAD(name) \        struct list_head name = LIST_HEAD_INIT(name)#define INIT_LIST_HEAD(ptr) do { \                  //初始化就是把指標指向自己        (ptr)->next = (ptr); (ptr)->prev = (ptr); \} while (0)

 

下面就是插入函數的具體分析，其實插入函數很簡單，只要學過C語言的都能懂，我在這裡只是簡單解釋下：

/** 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 *new1,                //插入新條目,插在prev與next中間                              struct list_head *prev,                //                              struct list_head *next){        next->prev = new1;        new1->next = next;        new1->prev = prev;        prev->next = new1;}/*** 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 *new1, struct list_head *head)   //頭插法，調用_list_add()實現{        __list_add(new1, 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 *new1, struct list_head *head)   //尾部插法{        __list_add(new1, head->prev, head);}