1#if !defined(_BLKID_LIST_H) && !defined(LIST_HEAD_INIT)
2#define _BLKID_LIST_H
3
4#ifdef __cplusplus
5extern "C" {
6#endif
7
8#ifdef __GNUC__
9#define _INLINE_ static __inline__
10#else                         /* For Watcom C */
11#define _INLINE_ static inline
12#endif
13
14/*
15 * Simple doubly linked list implementation.
16 *
17 * Some of the internal functions ("__xxx") are useful when
18 * manipulating whole lists rather than single entries, as
19 * sometimes we already know the next/prev entries and we can
20 * generate better code by using them directly rather than
21 * using the generic single-entry routines.
22 */
23
24struct list_head {
25	struct list_head *next, *prev;
26};
27
28#define LIST_HEAD_INIT(name) { &(name), &(name) }
29
30#define INIT_LIST_HEAD(ptr) do { \
31	(ptr)->next = (ptr); (ptr)->prev = (ptr); \
32} while (0)
33
34/*
35 * Insert a new entry between two known consecutive entries.
36 *
37 * This is only for internal list manipulation where we know
38 * the prev/next entries already!
39 */
40_INLINE_ void __list_add(struct list_head * add,
41	struct list_head * prev,
42	struct list_head * next)
43{
44	next->prev = add;
45	add->next = next;
46	add->prev = prev;
47	prev->next = add;
48}
49
50/**
51 * list_add - add a new entry
52 * @add:	new entry to be added
53 * @head:	list head to add it after
54 *
55 * Insert a new entry after the specified head.
56 * This is good for implementing stacks.
57 */
58_INLINE_ void list_add(struct list_head *add, struct list_head *head)
59{
60	__list_add(add, head, head->next);
61}
62
63/**
64 * list_add_tail - add a new entry
65 * @add:	new entry to be added
66 * @head:	list head to add it before
67 *
68 * Insert a new entry before the specified head.
69 * This is useful for implementing queues.
70 */
71_INLINE_ void list_add_tail(struct list_head *add, struct list_head *head)
72{
73	__list_add(add, head->prev, head);
74}
75
76/*
77 * Delete a list entry by making the prev/next entries
78 * point to each other.
79 *
80 * This is only for internal list manipulation where we know
81 * the prev/next entries already!
82 */
83_INLINE_ void __list_del(struct list_head * prev,
84				  struct list_head * next)
85{
86	next->prev = prev;
87	prev->next = next;
88}
89
90/**
91 * list_del - deletes entry from list.
92 * @entry:	the element to delete from the list.
93 *
94 * list_empty() on @entry does not return true after this, @entry is
95 * in an undefined state.
96 */
97_INLINE_ void list_del(struct list_head *entry)
98{
99	__list_del(entry->prev, entry->next);
100}
101
102/**
103 * list_del_init - deletes entry from list and reinitialize it.
104 * @entry:	the element to delete from the list.
105 */
106_INLINE_ void list_del_init(struct list_head *entry)
107{
108	__list_del(entry->prev, entry->next);
109	INIT_LIST_HEAD(entry);
110}
111
112/**
113 * list_empty - tests whether a list is empty
114 * @head:	the list to test.
115 */
116_INLINE_ int list_empty(struct list_head *head)
117{
118	return head->next == head;
119}
120
121/**
122 * list_splice - join two lists
123 * @list:	the new list to add.
124 * @head:	the place to add it in the first list.
125 */
126_INLINE_ void list_splice(struct list_head *list, struct list_head *head)
127{
128	struct list_head *first = list->next;
129
130	if (first != list) {
131		struct list_head *last = list->prev;
132		struct list_head *at = head->next;
133
134		first->prev = head;
135		head->next = first;
136
137		last->next = at;
138		at->prev = last;
139	}
140}
141
142/**
143 * list_entry - get the struct for this entry
144 * @ptr:	the &struct list_head pointer.
145 * @type:	the type of the struct this is embedded in.
146 * @member:	the name of the list_struct within the struct.
147 */
148#define list_entry(ptr, type, member) \
149	((type *)((char *)(ptr)-(unsigned long)(&((type *)0)->member)))
150
151/**
152 * list_for_each - iterate over elements in a list
153 * @pos:	the &struct list_head to use as a loop counter.
154 * @head:	the head for your list.
155 */
156#define list_for_each(pos, head) \
157	for (pos = (head)->next; pos != (head); pos = pos->next)
158
159/**
160 * list_for_each_safe - iterate over elements in a list, but don't dereference
161 *                      pos after the body is done (in case it is freed)
162 * @pos:	the &struct list_head to use as a loop counter.
163 * @pnext:	the &struct list_head to use as a pointer to the next item.
164 * @head:	the head for your list (not included in iteration).
165 */
166#define list_for_each_safe(pos, pnext, head) \
167	for (pos = (head)->next, pnext = pos->next; pos != (head); \
168	     pos = pnext, pnext = pos->next)
169
170#undef _INLINE_
171
172#ifdef __cplusplus
173}
174#endif
175
176#endif /* _BLKID_LIST_H */
177