6 * Simple doubly linked list implementation.
8 * Some of the internal functions ("__xxx") are useful when
9 * manipulating whole lists rather than single entries, as
10 * sometimes we already know the next/prev entries and we can
11 * generate better code by using them directly rather than
12 * using the generic single-entry routines.
16 struct list_head *next, *prev;
19 #define LIST_HEAD_INIT(name) { &(name), &(name) }
21 #define LIST_HEAD(name) \
22 struct list_head name = LIST_HEAD_INIT(name)
24 #define INIT_LIST_HEAD(ptr) do { \
25 (ptr)->next = (ptr); (ptr)->prev = (ptr); \
29 * Insert a new entry between two known consecutive entries.
31 * This is only for internal list manipulation where we know
32 * the prev/next entries already!
34 static __inline__ void __list_add(struct list_head * new,
35 struct list_head * prev,
36 struct list_head * next)
45 * list_add - add a new entry
46 * @new: new entry to be added
47 * @head: list head to add it after
49 * Insert a new entry after the specified head.
50 * This is good for implementing stacks.
52 static __inline__ void list_add(struct list_head *new, struct list_head *head)
54 __list_add(new, head, head->next);
58 * list_add_tail - add a new entry
59 * @new: new entry to be added
60 * @head: list head to add it before
62 * Insert a new entry before the specified head.
63 * This is useful for implementing queues.
65 static __inline__ void list_add_tail(struct list_head *new, struct list_head *head)
67 __list_add(new, head->prev, head);
71 * Delete a list entry by making the prev/next entries
72 * point to each other.
74 * This is only for internal list manipulation where we know
75 * the prev/next entries already!
77 static __inline__ void __list_del(struct list_head * prev,
78 struct list_head * next)
85 * list_del - deletes entry from list.
86 * @entry: the element to delete from the list.
87 * Note: list_empty on entry does not return true after this, the entry is in an undefined state.
89 static __inline__ void list_del(struct list_head *entry)
91 __list_del(entry->prev, entry->next);
95 * list_del_init - deletes entry from list and reinitialize it.
96 * @entry: the element to delete from the list.
98 static __inline__ void list_del_init(struct list_head *entry)
100 __list_del(entry->prev, entry->next);
101 INIT_LIST_HEAD(entry);
105 * list_empty - tests whether a list is empty
106 * @head: the list to test.
108 static __inline__ int list_empty(struct list_head *head)
110 return head->next == head;
114 * list_splice - join two lists
115 * @list: the new list to add.
116 * @head: the place to add it in the first list.
118 static __inline__ void list_splice(struct list_head *list, struct list_head *head)
120 struct list_head *first = list->next;
123 struct list_head *last = list->prev;
124 struct list_head *at = head->next;
135 * list_entry - get the struct for this entry
136 * @ptr: the &struct list_head pointer.
137 * @type: the type of the struct this is embedded in.
138 * @member: the name of the list_struct within the struct.
140 #define list_entry(ptr, type, member) \
141 ((type *)((char *)(ptr)-(unsigned long)(&((type *)0)->member)))
144 * list_for_each - iterate over a list
145 * @pos: the &struct list_head to use as a loop counter.
146 * @head: the head for your list.
148 #define list_for_each(pos, head) \
149 for (pos = (head)->next; pos != (head); pos = pos->next)
152 * list_for_each_safe - iterate over a list safe against removal of list entry
153 * @pos: the &struct list_head to use as a loop counter.
154 * @n: another &struct list_head to use as temporary storage
155 * @head: the head for your list.
157 #define list_for_each_safe(pos, n, head) \
158 for (pos = (head)->next, n = pos->next; pos != (head); \
159 pos = n, n = pos->next)