4 #include <linux/types.h>
5 #include <linux/stddef.h>
6 #include <linux/poison.h>
7 #include <linux/const.h>
10 * Simple doubly linked list implementation.
12 * Some of the internal functions ("__xxx") are useful when
13 * manipulating whole lists rather than single entries, as
14 * sometimes we already know the next/prev entries and we can
15 * generate better code by using them directly rather than
16 * using the generic single-entry routines.
19 #define LIST_HEAD_INIT(name) { &(name), &(name) }
21 #define LIST_HEAD(name) \
22 struct list_head name = LIST_HEAD_INIT(name)
24 static inline void INIT_LIST_HEAD(struct list_head *list)
31 * Insert a new entry between two known consecutive entries.
33 * This is only for internal list manipulation where we know
34 * the prev/next entries already!
36 #ifndef CONFIG_DEBUG_LIST
37 static inline void __list_add(struct list_head *new,
38 struct list_head *prev,
39 struct list_head *next)
47 extern void __list_add(struct list_head *new,
48 struct list_head *prev,
49 struct list_head *next);
53 * list_add - add a new entry
54 * @new: new entry to be added
55 * @head: list head to add it after
57 * Insert a new entry after the specified head.
58 * This is good for implementing stacks.
60 static inline void list_add(struct list_head *new, struct list_head *head)
62 __list_add(new, head, head->next);
67 * list_add_tail - add a new entry
68 * @new: new entry to be added
69 * @head: list head to add it before
71 * Insert a new entry before the specified head.
72 * This is useful for implementing queues.
74 static inline void list_add_tail(struct list_head *new, struct list_head *head)
76 __list_add(new, head->prev, head);
80 * Delete a list entry by making the prev/next entries
81 * point to each other.
83 * This is only for internal list manipulation where we know
84 * the prev/next entries already!
86 static inline void __list_del(struct list_head * prev, struct list_head * next)
93 * list_del - deletes entry from list.
94 * @entry: the element to delete from the list.
95 * Note: list_empty() on entry does not return true after this, the entry is
96 * in an undefined state.
98 #ifndef CONFIG_DEBUG_LIST
99 static inline void __list_del_entry(struct list_head *entry)
101 __list_del(entry->prev, entry->next);
104 static inline void list_del(struct list_head *entry)
106 __list_del(entry->prev, entry->next);
107 entry->next = LIST_POISON1;
108 entry->prev = LIST_POISON2;
111 extern void __list_del_entry(struct list_head *entry);
112 extern void list_del(struct list_head *entry);
116 * list_replace - replace old entry by new one
117 * @old : the element to be replaced
118 * @new : the new element to insert
120 * If @old was empty, it will be overwritten.
122 static inline void list_replace(struct list_head *old,
123 struct list_head *new)
125 new->next = old->next;
126 new->next->prev = new;
127 new->prev = old->prev;
128 new->prev->next = new;
131 static inline void list_replace_init(struct list_head *old,
132 struct list_head *new)
134 list_replace(old, new);
139 * list_del_init - deletes entry from list and reinitialize it.
140 * @entry: the element to delete from the list.
142 static inline void list_del_init(struct list_head *entry)
144 __list_del_entry(entry);
145 INIT_LIST_HEAD(entry);
149 * list_move - delete from one list and add as another's head
150 * @list: the entry to move
151 * @head: the head that will precede our entry
153 static inline void list_move(struct list_head *list, struct list_head *head)
155 __list_del_entry(list);
156 list_add(list, head);
160 * list_move_tail - delete from one list and add as another's tail
161 * @list: the entry to move
162 * @head: the head that will follow our entry
164 static inline void list_move_tail(struct list_head *list,
165 struct list_head *head)
167 __list_del_entry(list);
168 list_add_tail(list, head);
172 * list_is_last - tests whether @list is the last entry in list @head
173 * @list: the entry to test
174 * @head: the head of the list
176 static inline int list_is_last(const struct list_head *list,
177 const struct list_head *head)
179 return list->next == head;
183 * list_empty - tests whether a list is empty
184 * @head: the list to test.
186 static inline int list_empty(const struct list_head *head)
188 return head->next == head;
192 * list_empty_careful - tests whether a list is empty and not being modified
193 * @head: the list to test
196 * tests whether a list is empty _and_ checks that no other CPU might be
197 * in the process of modifying either member (next or prev)
199 * NOTE: using list_empty_careful() without synchronization
200 * can only be safe if the only activity that can happen
201 * to the list entry is list_del_init(). Eg. it cannot be used
202 * if another CPU could re-list_add() it.
204 static inline int list_empty_careful(const struct list_head *head)
206 struct list_head *next = head->next;
207 return (next == head) && (next == head->prev);
211 * list_rotate_left - rotate the list to the left
212 * @head: the head of the list
214 static inline void list_rotate_left(struct list_head *head)
216 struct list_head *first;
218 if (!list_empty(head)) {
220 list_move_tail(first, head);
225 * list_is_singular - tests whether a list has just one entry.
226 * @head: the list to test.
228 static inline int list_is_singular(const struct list_head *head)
230 return !list_empty(head) && (head->next == head->prev);
233 static inline void __list_cut_position(struct list_head *list,
234 struct list_head *head, struct list_head *entry)
236 struct list_head *new_first = entry->next;
237 list->next = head->next;
238 list->next->prev = list;
241 head->next = new_first;
242 new_first->prev = head;
246 * list_cut_position - cut a list into two
247 * @list: a new list to add all removed entries
248 * @head: a list with entries
249 * @entry: an entry within head, could be the head itself
250 * and if so we won't cut the list
252 * This helper moves the initial part of @head, up to and
253 * including @entry, from @head to @list. You should
254 * pass on @entry an element you know is on @head. @list
255 * should be an empty list or a list you do not care about
259 static inline void list_cut_position(struct list_head *list,
260 struct list_head *head, struct list_head *entry)
262 if (list_empty(head))
264 if (list_is_singular(head) &&
265 (head->next != entry && head != entry))
268 INIT_LIST_HEAD(list);
270 __list_cut_position(list, head, entry);
273 static inline void __list_splice(const struct list_head *list,
274 struct list_head *prev,
275 struct list_head *next)
277 struct list_head *first = list->next;
278 struct list_head *last = list->prev;
288 * list_splice - join two lists, this is designed for stacks
289 * @list: the new list to add.
290 * @head: the place to add it in the first list.
292 static inline void list_splice(const struct list_head *list,
293 struct list_head *head)
295 if (!list_empty(list))
296 __list_splice(list, head, head->next);
300 * list_splice_tail - join two lists, each list being a queue
301 * @list: the new list to add.
302 * @head: the place to add it in the first list.
304 static inline void list_splice_tail(struct list_head *list,
305 struct list_head *head)
307 if (!list_empty(list))
308 __list_splice(list, head->prev, head);
312 * list_splice_init - join two lists and reinitialise the emptied list.
313 * @list: the new list to add.
314 * @head: the place to add it in the first list.
316 * The list at @list is reinitialised
318 static inline void list_splice_init(struct list_head *list,
319 struct list_head *head)
321 if (!list_empty(list)) {
322 __list_splice(list, head, head->next);
323 INIT_LIST_HEAD(list);
328 * list_splice_tail_init - join two lists and reinitialise the emptied list
329 * @list: the new list to add.
330 * @head: the place to add it in the first list.
332 * Each of the lists is a queue.
333 * The list at @list is reinitialised
335 static inline void list_splice_tail_init(struct list_head *list,
336 struct list_head *head)
338 if (!list_empty(list)) {
339 __list_splice(list, head->prev, head);
340 INIT_LIST_HEAD(list);
345 * list_entry - get the struct for this entry
346 * @ptr: the &struct list_head pointer.
347 * @type: the type of the struct this is embedded in.
348 * @member: the name of the list_struct within the struct.
350 #define list_entry(ptr, type, member) \
351 container_of(ptr, type, member)
354 * list_first_entry - get the first element from a list
355 * @ptr: the list head to take the element from.
356 * @type: the type of the struct this is embedded in.
357 * @member: the name of the list_struct within the struct.
359 * Note, that list is expected to be not empty.
361 #define list_first_entry(ptr, type, member) \
362 list_entry((ptr)->next, type, member)
365 * list_first_entry_or_null - get the first element from a list
366 * @ptr: the list head to take the element from.
367 * @type: the type of the struct this is embedded in.
368 * @member: the name of the list_struct within the struct.
370 * Note that if the list is empty, it returns NULL.
372 #define list_first_entry_or_null(ptr, type, member) \
373 (!list_empty(ptr) ? list_first_entry(ptr, type, member) : NULL)
376 * list_for_each - iterate over a list
377 * @pos: the &struct list_head to use as a loop cursor.
378 * @head: the head for your list.
380 #define list_for_each(pos, head) \
381 for (pos = (head)->next; pos != (head); pos = pos->next)
384 * __list_for_each - iterate over a list
385 * @pos: the &struct list_head to use as a loop cursor.
386 * @head: the head for your list.
388 * This variant doesn't differ from list_for_each() any more.
389 * We don't do prefetching in either case.
391 #define __list_for_each(pos, head) \
392 for (pos = (head)->next; pos != (head); pos = pos->next)
395 * list_for_each_prev - iterate over a list backwards
396 * @pos: the &struct list_head to use as a loop cursor.
397 * @head: the head for your list.
399 #define list_for_each_prev(pos, head) \
400 for (pos = (head)->prev; pos != (head); pos = pos->prev)
403 * list_for_each_safe - iterate over a list safe against removal of list entry
404 * @pos: the &struct list_head to use as a loop cursor.
405 * @n: another &struct list_head to use as temporary storage
406 * @head: the head for your list.
408 #define list_for_each_safe(pos, n, head) \
409 for (pos = (head)->next, n = pos->next; pos != (head); \
410 pos = n, n = pos->next)
413 * list_for_each_prev_safe - iterate over a list backwards safe against removal of list entry
414 * @pos: the &struct list_head to use as a loop cursor.
415 * @n: another &struct list_head to use as temporary storage
416 * @head: the head for your list.
418 #define list_for_each_prev_safe(pos, n, head) \
419 for (pos = (head)->prev, n = pos->prev; \
421 pos = n, n = pos->prev)
424 * list_for_each_entry - iterate over list of given type
425 * @pos: the type * to use as a loop cursor.
426 * @head: the head for your list.
427 * @member: the name of the list_struct within the struct.
429 #define list_for_each_entry(pos, head, member) \
430 for (pos = list_entry((head)->next, typeof(*pos), member); \
431 &pos->member != (head); \
432 pos = list_entry(pos->member.next, typeof(*pos), member))
435 * list_for_each_entry_reverse - iterate backwards over list of given type.
436 * @pos: the type * to use as a loop cursor.
437 * @head: the head for your list.
438 * @member: the name of the list_struct within the struct.
440 #define list_for_each_entry_reverse(pos, head, member) \
441 for (pos = list_entry((head)->prev, typeof(*pos), member); \
442 &pos->member != (head); \
443 pos = list_entry(pos->member.prev, typeof(*pos), member))
446 * list_prepare_entry - prepare a pos entry for use in list_for_each_entry_continue()
447 * @pos: the type * to use as a start point
448 * @head: the head of the list
449 * @member: the name of the list_struct within the struct.
451 * Prepares a pos entry for use as a start point in list_for_each_entry_continue().
453 #define list_prepare_entry(pos, head, member) \
454 ((pos) ? : list_entry(head, typeof(*pos), member))
457 * list_for_each_entry_continue - continue iteration over list of given type
458 * @pos: the type * to use as a loop cursor.
459 * @head: the head for your list.
460 * @member: the name of the list_struct within the struct.
462 * Continue to iterate over list of given type, continuing after
463 * the current position.
465 #define list_for_each_entry_continue(pos, head, member) \
466 for (pos = list_entry(pos->member.next, typeof(*pos), member); \
467 &pos->member != (head); \
468 pos = list_entry(pos->member.next, typeof(*pos), member))
471 * list_for_each_entry_continue_reverse - iterate backwards from the given point
472 * @pos: the type * to use as a loop cursor.
473 * @head: the head for your list.
474 * @member: the name of the list_struct within the struct.
476 * Start to iterate over list of given type backwards, continuing after
477 * the current position.
479 #define list_for_each_entry_continue_reverse(pos, head, member) \
480 for (pos = list_entry(pos->member.prev, typeof(*pos), member); \
481 &pos->member != (head); \
482 pos = list_entry(pos->member.prev, typeof(*pos), member))
485 * list_for_each_entry_from - iterate over list of given type from the current point
486 * @pos: the type * to use as a loop cursor.
487 * @head: the head for your list.
488 * @member: the name of the list_struct within the struct.
490 * Iterate over list of given type, continuing from current position.
492 #define list_for_each_entry_from(pos, head, member) \
493 for (; &pos->member != (head); \
494 pos = list_entry(pos->member.next, typeof(*pos), member))
497 * list_for_each_entry_safe - iterate over list of given type safe against removal of list entry
498 * @pos: the type * to use as a loop cursor.
499 * @n: another type * to use as temporary storage
500 * @head: the head for your list.
501 * @member: the name of the list_struct within the struct.
503 #define list_for_each_entry_safe(pos, n, head, member) \
504 for (pos = list_entry((head)->next, typeof(*pos), member), \
505 n = list_entry(pos->member.next, typeof(*pos), member); \
506 &pos->member != (head); \
507 pos = n, n = list_entry(n->member.next, typeof(*n), member))
510 * list_for_each_entry_safe_continue - continue list iteration safe against removal
511 * @pos: the type * to use as a loop cursor.
512 * @n: another type * to use as temporary storage
513 * @head: the head for your list.
514 * @member: the name of the list_struct within the struct.
516 * Iterate over list of given type, continuing after current point,
517 * safe against removal of list entry.
519 #define list_for_each_entry_safe_continue(pos, n, head, member) \
520 for (pos = list_entry(pos->member.next, typeof(*pos), member), \
521 n = list_entry(pos->member.next, typeof(*pos), member); \
522 &pos->member != (head); \
523 pos = n, n = list_entry(n->member.next, typeof(*n), member))
526 * list_for_each_entry_safe_from - iterate over list from current point safe against removal
527 * @pos: the type * to use as a loop cursor.
528 * @n: another type * to use as temporary storage
529 * @head: the head for your list.
530 * @member: the name of the list_struct within the struct.
532 * Iterate over list of given type from current point, safe against
533 * removal of list entry.
535 #define list_for_each_entry_safe_from(pos, n, head, member) \
536 for (n = list_entry(pos->member.next, typeof(*pos), member); \
537 &pos->member != (head); \
538 pos = n, n = list_entry(n->member.next, typeof(*n), member))
541 * list_for_each_entry_safe_reverse - iterate backwards over list safe against removal
542 * @pos: the type * to use as a loop cursor.
543 * @n: another type * to use as temporary storage
544 * @head: the head for your list.
545 * @member: the name of the list_struct within the struct.
547 * Iterate backwards over list of given type, safe against removal
550 #define list_for_each_entry_safe_reverse(pos, n, head, member) \
551 for (pos = list_entry((head)->prev, typeof(*pos), member), \
552 n = list_entry(pos->member.prev, typeof(*pos), member); \
553 &pos->member != (head); \
554 pos = n, n = list_entry(n->member.prev, typeof(*n), member))
557 * list_safe_reset_next - reset a stale list_for_each_entry_safe loop
558 * @pos: the loop cursor used in the list_for_each_entry_safe loop
559 * @n: temporary storage used in list_for_each_entry_safe
560 * @member: the name of the list_struct within the struct.
562 * list_safe_reset_next is not safe to use in general if the list may be
563 * modified concurrently (eg. the lock is dropped in the loop body). An
564 * exception to this is if the cursor element (pos) is pinned in the list,
565 * and list_safe_reset_next is called after re-taking the lock and before
566 * completing the current iteration of the loop body.
568 #define list_safe_reset_next(pos, n, member) \
569 n = list_entry(pos->member.next, typeof(*pos), member)
572 * Double linked lists with a single pointer list head.
573 * Mostly useful for hash tables where the two pointer list head is
575 * You lose the ability to access the tail in O(1).
578 #define HLIST_HEAD_INIT { .first = NULL }
579 #define HLIST_HEAD(name) struct hlist_head name = { .first = NULL }
580 #define INIT_HLIST_HEAD(ptr) ((ptr)->first = NULL)
581 static inline void INIT_HLIST_NODE(struct hlist_node *h)
587 static inline int hlist_unhashed(const struct hlist_node *h)
592 static inline int hlist_empty(const struct hlist_head *h)
597 static inline void __hlist_del(struct hlist_node *n)
599 struct hlist_node *next = n->next;
600 struct hlist_node **pprev = n->pprev;
606 static inline void hlist_del(struct hlist_node *n)
609 n->next = LIST_POISON1;
610 n->pprev = LIST_POISON2;
613 static inline void hlist_del_init(struct hlist_node *n)
615 if (!hlist_unhashed(n)) {
621 static inline void hlist_add_head(struct hlist_node *n, struct hlist_head *h)
623 struct hlist_node *first = h->first;
626 first->pprev = &n->next;
628 n->pprev = &h->first;
631 /* next must be != NULL */
632 static inline void hlist_add_before(struct hlist_node *n,
633 struct hlist_node *next)
635 n->pprev = next->pprev;
637 next->pprev = &n->next;
641 static inline void hlist_add_after(struct hlist_node *n,
642 struct hlist_node *next)
644 next->next = n->next;
646 next->pprev = &n->next;
649 next->next->pprev = &next->next;
652 /* after that we'll appear to be on some hlist and hlist_del will work */
653 static inline void hlist_add_fake(struct hlist_node *n)
659 * Move a list from one list head to another. Fixup the pprev
660 * reference of the first entry if it exists.
662 static inline void hlist_move_list(struct hlist_head *old,
663 struct hlist_head *new)
665 new->first = old->first;
667 new->first->pprev = &new->first;
671 #define hlist_entry(ptr, type, member) container_of(ptr,type,member)
673 #define hlist_for_each(pos, head) \
674 for (pos = (head)->first; pos ; pos = pos->next)
676 #define hlist_for_each_safe(pos, n, head) \
677 for (pos = (head)->first; pos && ({ n = pos->next; 1; }); \
680 #define hlist_entry_safe(ptr, type, member) \
681 ({ typeof(ptr) ____ptr = (ptr); \
682 ____ptr ? hlist_entry(____ptr, type, member) : NULL; \
686 * hlist_for_each_entry - iterate over list of given type
687 * @pos: the type * to use as a loop cursor.
688 * @head: the head for your list.
689 * @member: the name of the hlist_node within the struct.
691 #define hlist_for_each_entry(pos, head, member) \
692 for (pos = hlist_entry_safe((head)->first, typeof(*(pos)), member);\
694 pos = hlist_entry_safe((pos)->member.next, typeof(*(pos)), member))
697 * hlist_for_each_entry_continue - iterate over a hlist continuing after current point
698 * @pos: the type * to use as a loop cursor.
699 * @member: the name of the hlist_node within the struct.
701 #define hlist_for_each_entry_continue(pos, member) \
702 for (pos = hlist_entry_safe((pos)->member.next, typeof(*(pos)), member);\
704 pos = hlist_entry_safe((pos)->member.next, typeof(*(pos)), member))
707 * hlist_for_each_entry_from - iterate over a hlist continuing from current point
708 * @pos: the type * to use as a loop cursor.
709 * @member: the name of the hlist_node within the struct.
711 #define hlist_for_each_entry_from(pos, member) \
713 pos = hlist_entry_safe((pos)->member.next, typeof(*(pos)), member))
716 * hlist_for_each_entry_safe - iterate over list of given type safe against removal of list entry
717 * @pos: the type * to use as a loop cursor.
718 * @n: another &struct hlist_node to use as temporary storage
719 * @head: the head for your list.
720 * @member: the name of the hlist_node within the struct.
722 #define hlist_for_each_entry_safe(pos, n, head, member) \
723 for (pos = hlist_entry_safe((head)->first, typeof(*pos), member);\
724 pos && ({ n = pos->member.next; 1; }); \
725 pos = hlist_entry_safe(n, typeof(*pos), member))