1#ifndef _LINUX_LIST_H
2#define _LINUX_LIST_H
3
4#if defined(__KERNEL__) || defined(_LVM_H_INCLUDE)
5
6#include <linux/prefetch.h>
7
8/*
9 * Simple doubly linked list implementation.
10 *
11 * Some of the internal functions ("__xxx") are useful when
12 * manipulating whole lists rather than single entries, as
13 * sometimes we already know the next/prev entries and we can
14 * generate better code by using them directly rather than
15 * using the generic single-entry routines.
16 */
17
18struct list_head {
19	struct list_head *next, *prev;
20};
21
22#define LIST_HEAD_INIT(name) { &(name), &(name) }
23
24#define LIST_HEAD(name) \
25	struct list_head name = LIST_HEAD_INIT(name)
26
27#define INIT_LIST_HEAD(ptr) do { \
28	(ptr)->next = (ptr); (ptr)->prev = (ptr); \
29} while (0)
30
31/*
32 * Insert a new entry between two known consecutive entries. 
33 *
34 * This is only for internal list manipulation where we know
35 * the prev/next entries already!
36 */
37static inline void __list_add(struct list_head *new,
38			      struct list_head *prev,
39			      struct list_head *next)
40{
41	next->prev = new;
42	new->next = next;
43	new->prev = prev;
44	prev->next = new;
45}
46
47/**
48 * list_add - add a new entry
49 * @new: new entry to be added
50 * @head: list head to add it after
51 *
52 * Insert a new entry after the specified head.
53 * This is good for implementing stacks.
54 */
55static inline void list_add(struct list_head *new, struct list_head *head)
56{
57	__list_add(new, head, head->next);
58}
59
60/**
61 * list_add_tail - add a new entry
62 * @new: new entry to be added
63 * @head: list head to add it before
64 *
65 * Insert a new entry before the specified head.
66 * This is useful for implementing queues.
67 */
68static inline void list_add_tail(struct list_head *new, struct list_head *head)
69{
70	__list_add(new, head->prev, head);
71}
72
73/*
74 * Delete a list entry by making the prev/next entries
75 * point to each other.
76 *
77 * This is only for internal list manipulation where we know
78 * the prev/next entries already!
79 */
80static inline void __list_del(struct list_head *prev, struct list_head *next)
81{
82	next->prev = prev;
83	prev->next = next;
84}
85
86/**
87 * list_del - deletes entry from list.
88 * @entry: the element to delete from the list.
89 * Note: list_empty on entry does not return true after this, the entry is in an undefined state.
90 */
91static inline void list_del(struct list_head *entry)
92{
93	__list_del(entry->prev, entry->next);
94	entry->next = (void *) 0;
95	entry->prev = (void *) 0;
96}
97
98/**
99 * list_del_init - deletes entry from list and reinitialize it.
100 * @entry: the element to delete from the list.
101 */
102static inline void list_del_init(struct list_head *entry)
103{
104	__list_del(entry->prev, entry->next);
105	INIT_LIST_HEAD(entry); 
106}
107
108/**
109 * list_move - delete from one list and add as another's head
110 * @list: the entry to move
111 * @head: the head that will precede our entry
112 */
113static inline void list_move(struct list_head *list, struct list_head *head)
114{
115        __list_del(list->prev, list->next);
116        list_add(list, head);
117}
118
119/**
120 * list_move_tail - delete from one list and add as another's tail
121 * @list: the entry to move
122 * @head: the head that will follow our entry
123 */
124static inline void list_move_tail(struct list_head *list,
125				  struct list_head *head)
126{
127        __list_del(list->prev, list->next);
128        list_add_tail(list, head);
129}
130
131/**
132 * list_empty - tests whether a list is empty
133 * @head: the list to test.
134 */
135static inline int list_empty(struct list_head *head)
136{
137	return head->next == head;
138}
139
140static inline void __list_splice(struct list_head *list,
141				 struct list_head *head)
142{
143	struct list_head *first = list->next;
144	struct list_head *last = list->prev;
145	struct list_head *at = head->next;
146
147	first->prev = head;
148	head->next = first;
149
150	last->next = at;
151	at->prev = last;
152}
153
154/**
155 * list_splice - join two lists
156 * @list: the new list to add.
157 * @head: the place to add it in the first list.
158 */
159static inline void list_splice(struct list_head *list, struct list_head *head)
160{
161	if (!list_empty(list))
162		__list_splice(list, head);
163}
164
165/**
166 * list_splice_init - join two lists and reinitialise the emptied list.
167 * @list: the new list to add.
168 * @head: the place to add it in the first list.
169 *
170 * The list at @list is reinitialised
171 */
172static inline void list_splice_init(struct list_head *list,
173				    struct list_head *head)
174{
175	if (!list_empty(list)) {
176		__list_splice(list, head);
177		INIT_LIST_HEAD(list);
178	}
179}
180
181/**
182 * list_entry - get the struct for this entry
183 * @ptr:	the &struct list_head pointer.
184 * @type:	the type of the struct this is embedded in.
185 * @member:	the name of the list_struct within the struct.
186 */
187#define list_entry(ptr, type, member) \
188	((type *)((char *)(ptr)-(unsigned long)(&((type *)0)->member)))
189
190/**
191 * list_for_each	-	iterate over a list
192 * @pos:	the &struct list_head to use as a loop counter.
193 * @head:	the head for your list.
194 */
195#define list_for_each(pos, head) \
196	for (pos = (head)->next, prefetch(pos->next); pos != (head); \
197        	pos = pos->next, prefetch(pos->next))
198/**
199 * list_for_each_prev	-	iterate over a list backwards
200 * @pos:	the &struct list_head to use as a loop counter.
201 * @head:	the head for your list.
202 */
203#define list_for_each_prev(pos, head) \
204	for (pos = (head)->prev, prefetch(pos->prev); pos != (head); \
205        	pos = pos->prev, prefetch(pos->prev))
206        	
207/**
208 * list_for_each_safe	-	iterate over a list safe against removal of list entry
209 * @pos:	the &struct list_head to use as a loop counter.
210 * @n:		another &struct list_head to use as temporary storage
211 * @head:	the head for your list.
212 */
213#define list_for_each_safe(pos, n, head) \
214	for (pos = (head)->next, n = pos->next; pos != (head); \
215		pos = n, n = pos->next)
216
217/**
218 * list_for_each_entry	-	iterate over list of given type
219 * @pos:	the type * to use as a loop counter.
220 * @head:	the head for your list.
221 * @member:	the name of the list_struct within the struct.
222 */
223#define list_for_each_entry(pos, head, member)				\
224	for (pos = list_entry((head)->next, typeof(*pos), member),	\
225		     prefetch(pos->member.next);			\
226	     &pos->member != (head); 					\
227	     pos = list_entry(pos->member.next, typeof(*pos), member),	\
228		     prefetch(pos->member.next))
229
230#endif /* __KERNEL__ || _LVM_H_INCLUDE */
231
232#endif
233