5 #include <linux/list.h>
8 * Simple doubly linked list implementation.
10 * Some of the internal functions ("__xxx") are useful when
11 * manipulating whole lists rather than single entries, as
12 * sometimes we already know the next/prev entries and we can
13 * generate better code by using them directly rather than
14 * using the generic single-entry routines.
17 #define prefetch(a) ((void)a)
20 struct list_head *next, *prev;
23 typedef struct list_head list_t;
25 #define LIST_HEAD_INIT(name) { &(name), &(name) }
27 #define LIST_HEAD(name) \
28 struct list_head name = LIST_HEAD_INIT(name)
30 #define INIT_LIST_HEAD(ptr) do { \
31 (ptr)->next = (ptr); (ptr)->prev = (ptr); \
35 * Insert a new entry between two known consecutive entries.
37 * This is only for internal list manipulation where we know
38 * the prev/next entries already!
40 static inline void __list_add(struct list_head * new,
41 struct list_head * prev,
42 struct list_head * next)
51 * list_add - add a new entry
52 * @new: new entry to be added
53 * @head: list head to add it after
55 * Insert a new entry after the specified head.
56 * This is good for implementing stacks.
58 static inline void list_add(struct list_head *new, struct list_head *head)
60 __list_add(new, head, head->next);
64 * list_add_tail - add a new entry
65 * @new: new entry to be added
66 * @head: list head to add it before
68 * Insert a new entry before the specified head.
69 * This is useful for implementing queues.
71 static inline void list_add_tail(struct list_head *new, struct list_head *head)
73 __list_add(new, head->prev, head);
77 * Delete a list entry by making the prev/next entries
78 * point to each other.
80 * This is only for internal list manipulation where we know
81 * the prev/next entries already!
83 static inline void __list_del(struct list_head * prev, struct list_head * next)
90 * list_del - deletes entry from list.
91 * @entry: the element to delete from the list.
92 * Note: list_empty on entry does not return true after this, the entry is in an undefined state.
94 static inline void list_del(struct list_head *entry)
96 __list_del(entry->prev, entry->next);
100 * list_del_init - deletes entry from list and reinitialize it.
101 * @entry: the element to delete from the list.
103 static inline void list_del_init(struct list_head *entry)
105 __list_del(entry->prev, entry->next);
106 INIT_LIST_HEAD(entry);
110 * list_move - delete from one list and add as another's head
111 * @list: the entry to move
112 * @head: the head that will precede our entry
114 static inline void list_move(struct list_head *list, struct list_head *head)
116 __list_del(list->prev, list->next);
117 list_add(list, head);
121 * list_move_tail - delete from one list and add as another's tail
122 * @list: the entry to move
123 * @head: the head that will follow our entry
125 static inline void list_move_tail(struct list_head *list,
126 struct list_head *head)
128 __list_del(list->prev, list->next);
129 list_add_tail(list, head);
133 * list_empty - tests whether a list is empty
134 * @head: the list to test.
136 static inline int list_empty(struct list_head *head)
138 return head->next == head;
141 static inline void __list_splice(struct list_head *list,
142 struct list_head *head)
144 struct list_head *first = list->next;
145 struct list_head *last = list->prev;
146 struct list_head *at = head->next;
156 * list_splice - join two lists
157 * @list: the new list to add.
158 * @head: the place to add it in the first list.
160 static inline void list_splice(struct list_head *list, struct list_head *head)
162 if (!list_empty(list))
163 __list_splice(list, head);
167 * list_splice_init - join two lists and reinitialise the emptied list.
168 * @list: the new list to add.
169 * @head: the place to add it in the first list.
171 * The list at @list is reinitialised
173 static inline void list_splice_init(struct list_head *list,
174 struct list_head *head)
176 if (!list_empty(list)) {
177 __list_splice(list, head);
178 INIT_LIST_HEAD(list);
183 * list_entry - get the struct for this entry
184 * @ptr: the &struct list_head pointer.
185 * @type: the type of the struct this is embedded in.
186 * @member: the name of the list_struct within the struct.
188 #define list_entry(ptr, type, member) \
189 ((type *)((char *)(ptr)-(unsigned long)(&((type *)0)->member)))
192 * list_for_each - iterate over a list
193 * @pos: the &struct list_head to use as a loop counter.
194 * @head: the head for your list.
196 #define list_for_each(pos, head) \
197 for (pos = (head)->next, prefetch(pos->next); pos != (head); \
198 pos = pos->next, prefetch(pos->next))
201 * list_for_each_prev - iterate over a list in reverse order
202 * @pos: the &struct list_head to use as a loop counter.
203 * @head: the head for your list.
205 #define list_for_each_prev(pos, head) \
206 for (pos = (head)->prev, prefetch(pos->prev); pos != (head); \
207 pos = pos->prev, prefetch(pos->prev))
210 * list_for_each_safe - iterate over a list safe against removal of list entry
211 * @pos: the &struct list_head to use as a loop counter.
212 * @n: another &struct list_head to use as temporary storage
213 * @head: the head for your list.
215 #define list_for_each_safe(pos, n, head) \
216 for (pos = (head)->next, n = pos->next; pos != (head); \
217 pos = n, n = pos->next)
220 * list_for_each_entry - iterate over list of given type
221 * @pos: the type * to use as a loop counter.
222 * @head: the head for your list.
223 * @member: the name of the list_struct within the struct.
225 #define list_for_each_entry(pos, head, member) \
226 for (pos = list_entry((head)->next, typeof(*pos), member), \
227 prefetch(pos->member.next); \
228 &pos->member != (head); \
229 pos = list_entry(pos->member.next, typeof(*pos), member), \
230 prefetch(pos->member.next))
233 * list_for_each_entry_safe - iterate over list of given type safe against removal of list entry
234 * @pos: the type * to use as a loop counter.
235 * @n: another type * to use as temporary storage
236 * @head: the head for your list.
237 * @member: the name of the list_struct within the struct.
239 #define list_for_each_entry_safe(pos, n, head, member) \
240 for (pos = list_entry((head)->next, typeof(*pos), member), \
241 n = list_entry(pos->member.next, typeof(*pos), member); \
242 &pos->member != (head); \
243 pos = n, n = list_entry(n->member.next, typeof(*n), member))
245 #endif /* if !__KERNEL__*/
246 #endif /* if !_LUSTRE_LIST_H */