浅谈linux内核中的list.h[2]

链表的删除
83/*
84 * Delete a list entry by making the prev/next entries
85 * point to each other.
86 *
87 * This is only for internal list manipulation where we know
88 * the prev/next entries already!
89 */
90static inline void __list_del(struct list_head * prev, struct list_head * next)
91{
92 next->prev = prev;
93 prev->next = next;
94}
该函数通过设置prev和next指针指向彼此，实现了删除二者之间节点的功能。但是这里我有个疑惑，删除的指针的释放在哪里实现。
96/**
97 * list_del - deletes entry from list.
98 * @entry: the element to delete from the list.
99 * Note: list_empty() on entry does not return true after this, the entry is
100 * in an undefined state.
101 */
102#ifndef CONFIG_DEBUG_LIST
103static inline void list_del(struct list_head *entry)
104{
105 __list_del(entry->prev, entry->next);
106 entry->next = LIST_POISON1;
107 entry->prev = LIST_POISON2;
108}
109#else
110extern void list_del(struct list_head *entry);
111#endif
该函数通过调用上面的内联函数实现节点的删除，这里的LIST_POISON1和LIST_POISON2是在linux/poison.h定义的。此处仍然是条件编译。
 
 
链表节点的置换
113/**
114 * list_replace - replace old entry by new one
115 * @old : the element to be replaced
116 * @new : the new element to insert
117 *
118 * If @old was empty, it will be overwritten.
119 */
120static inline void list_replace(struct list_head *old,
121 struct list_head *new)
122{
123 new->next = old->next;
124 new->next->prev = new;
125 new->prev = old->prev;
126 new->prev->next = new;
127}
128
129static inline void list_replace_init(struct list_head *old,
130 struct list_head *new)
131{
132 list_replace(old, new);
133 INIT_LIST_HEAD(old);
134}
静态内联函数list_replace接受两个参数：old和new，并通过new替换old。而list_replace_init函数则是通过调用list_replace进行替换，之后调用INIT_LIST_HEAD对被替换的old进行链表初始化。
 
 
链表的移动
146/**
147 * list_move - delete from one list