]>
git.proxmox.com Git - mirror_ubuntu-zesty-kernel.git/blob - include/linux/list.h
4 #include <linux/types.h>
5 #include <linux/stddef.h>
6 #include <linux/poison.h>
7 #include <linux/const.h>
8 #include <linux/kernel.h>
11 * Simple doubly linked list implementation.
13 * Some of the internal functions ("__xxx") are useful when
14 * manipulating whole lists rather than single entries, as
15 * sometimes we already know the next/prev entries and we can
16 * generate better code by using them directly rather than
17 * using the generic single-entry routines.
20 #define LIST_HEAD_INIT(name) { &(name), &(name) }
22 #define LIST_HEAD(name) \
23 struct list_head name = LIST_HEAD_INIT(name)
25 static inline void INIT_LIST_HEAD(struct list_head
*list
)
27 WRITE_ONCE(list
->next
, list
);
32 * Insert a new entry between two known consecutive entries.
34 * This is only for internal list manipulation where we know
35 * the prev/next entries already!
37 #ifndef CONFIG_DEBUG_LIST
38 static inline void __list_add(struct list_head
*new,
39 struct list_head
*prev
,
40 struct list_head
*next
)
45 WRITE_ONCE(prev
->next
, new);
48 extern void __list_add(struct list_head
*new,
49 struct list_head
*prev
,
50 struct list_head
*next
);
54 * list_add - add a new entry
55 * @new: new entry to be added
56 * @head: list head to add it after
58 * Insert a new entry after the specified head.
59 * This is good for implementing stacks.
61 static inline void list_add(struct list_head
*new, struct list_head
*head
)
63 __list_add(new, head
, head
->next
);
68 * list_add_tail - add a new entry
69 * @new: new entry to be added
70 * @head: list head to add it before
72 * Insert a new entry before the specified head.
73 * This is useful for implementing queues.
75 static inline void list_add_tail(struct list_head
*new, struct list_head
*head
)
77 __list_add(new, head
->prev
, head
);
81 * Delete a list entry by making the prev/next entries
82 * point to each other.
84 * This is only for internal list manipulation where we know
85 * the prev/next entries already!
87 static inline void __list_del(struct list_head
* prev
, struct list_head
* next
)
90 WRITE_ONCE(prev
->next
, next
);
94 * list_del - deletes entry from list.
95 * @entry: the element to delete from the list.
96 * Note: list_empty() on entry does not return true after this, the entry is
97 * in an undefined state.
99 #ifndef CONFIG_DEBUG_LIST
100 static inline void __list_del_entry(struct list_head
*entry
)
102 __list_del(entry
->prev
, entry
->next
);
105 static inline void list_del(struct list_head
*entry
)
107 __list_del(entry
->prev
, entry
->next
);
108 entry
->next
= LIST_POISON1
;
109 entry
->prev
= LIST_POISON2
;
112 extern void __list_del_entry(struct list_head
*entry
);
113 extern void list_del(struct list_head
*entry
);
117 * list_replace - replace old entry by new one
118 * @old : the element to be replaced
119 * @new : the new element to insert
121 * If @old was empty, it will be overwritten.
123 static inline void list_replace(struct list_head
*old
,
124 struct list_head
*new)
126 new->next
= old
->next
;
127 new->next
->prev
= new;
128 new->prev
= old
->prev
;
129 new->prev
->next
= new;
132 static inline void list_replace_init(struct list_head
*old
,
133 struct list_head
*new)
135 list_replace(old
, new);
140 * list_del_init - deletes entry from list and reinitialize it.
141 * @entry: the element to delete from the list.
143 static inline void list_del_init(struct list_head
*entry
)
145 __list_del_entry(entry
);
146 INIT_LIST_HEAD(entry
);
150 * list_move - delete from one list and add as another's head
151 * @list: the entry to move
152 * @head: the head that will precede our entry
154 static inline void list_move(struct list_head
*list
, struct list_head
*head
)
156 __list_del_entry(list
);
157 list_add(list
, head
);
161 * list_move_tail - delete from one list and add as another's tail
162 * @list: the entry to move
163 * @head: the head that will follow our entry
165 static inline void list_move_tail(struct list_head
*list
,
166 struct list_head
*head
)
168 __list_del_entry(list
);
169 list_add_tail(list
, head
);
173 * list_is_last - tests whether @list is the last entry in list @head
174 * @list: the entry to test
175 * @head: the head of the list
177 static inline int list_is_last(const struct list_head
*list
,
178 const struct list_head
*head
)
180 return list
->next
== head
;
184 * list_empty - tests whether a list is empty
185 * @head: the list to test.
187 static inline int list_empty(const struct list_head
*head
)
189 return READ_ONCE(head
->next
) == head
;
193 * list_empty_careful - tests whether a list is empty and not being modified
194 * @head: the list to test
197 * tests whether a list is empty _and_ checks that no other CPU might be
198 * in the process of modifying either member (next or prev)
200 * NOTE: using list_empty_careful() without synchronization
201 * can only be safe if the only activity that can happen
202 * to the list entry is list_del_init(). Eg. it cannot be used
203 * if another CPU could re-list_add() it.
205 static inline int list_empty_careful(const struct list_head
*head
)
207 struct list_head
*next
= head
->next
;
208 return (next
== head
) && (next
== head
->prev
);
212 * list_rotate_left - rotate the list to the left
213 * @head: the head of the list
215 static inline void list_rotate_left(struct list_head
*head
)
217 struct list_head
*first
;
219 if (!list_empty(head
)) {
221 list_move_tail(first
, head
);
226 * list_is_singular - tests whether a list has just one entry.
227 * @head: the list to test.
229 static inline int list_is_singular(const struct list_head
*head
)
231 return !list_empty(head
) && (head
->next
== head
->prev
);
234 static inline void __list_cut_position(struct list_head
*list
,
235 struct list_head
*head
, struct list_head
*entry
)
237 struct list_head
*new_first
= entry
->next
;
238 list
->next
= head
->next
;
239 list
->next
->prev
= list
;
242 head
->next
= new_first
;
243 new_first
->prev
= head
;
247 * list_cut_position - cut a list into two
248 * @list: a new list to add all removed entries
249 * @head: a list with entries
250 * @entry: an entry within head, could be the head itself
251 * and if so we won't cut the list
253 * This helper moves the initial part of @head, up to and
254 * including @entry, from @head to @list. You should
255 * pass on @entry an element you know is on @head. @list
256 * should be an empty list or a list you do not care about
260 static inline void list_cut_position(struct list_head
*list
,
261 struct list_head
*head
, struct list_head
*entry
)
263 if (list_empty(head
))
265 if (list_is_singular(head
) &&
266 (head
->next
!= entry
&& head
!= entry
))
269 INIT_LIST_HEAD(list
);
271 __list_cut_position(list
, head
, entry
);
274 static inline void __list_splice(const struct list_head
*list
,
275 struct list_head
*prev
,
276 struct list_head
*next
)
278 struct list_head
*first
= list
->next
;
279 struct list_head
*last
= list
->prev
;
289 * list_splice - join two lists, this is designed for stacks
290 * @list: the new list to add.
291 * @head: the place to add it in the first list.
293 static inline void list_splice(const struct list_head
*list
,
294 struct list_head
*head
)
296 if (!list_empty(list
))
297 __list_splice(list
, head
, head
->next
);
301 * list_splice_tail - join two lists, each list being a queue
302 * @list: the new list to add.
303 * @head: the place to add it in the first list.
305 static inline void list_splice_tail(struct list_head
*list
,
306 struct list_head
*head
)
308 if (!list_empty(list
))
309 __list_splice(list
, head
->prev
, head
);
313 * list_splice_init - join two lists and reinitialise the emptied list.
314 * @list: the new list to add.
315 * @head: the place to add it in the first list.
317 * The list at @list is reinitialised
319 static inline void list_splice_init(struct list_head
*list
,
320 struct list_head
*head
)
322 if (!list_empty(list
)) {
323 __list_splice(list
, head
, head
->next
);
324 INIT_LIST_HEAD(list
);
329 * list_splice_tail_init - join two lists and reinitialise the emptied list
330 * @list: the new list to add.
331 * @head: the place to add it in the first list.
333 * Each of the lists is a queue.
334 * The list at @list is reinitialised
336 static inline void list_splice_tail_init(struct list_head
*list
,
337 struct list_head
*head
)
339 if (!list_empty(list
)) {
340 __list_splice(list
, head
->prev
, head
);
341 INIT_LIST_HEAD(list
);
346 * list_entry - get the struct for this entry
347 * @ptr: the &struct list_head pointer.
348 * @type: the type of the struct this is embedded in.
349 * @member: the name of the list_head within the struct.
351 #define list_entry(ptr, type, member) \
352 container_of(ptr, type, member)
355 * list_first_entry - get the first element from a list
356 * @ptr: the list head to take the element from.
357 * @type: the type of the struct this is embedded in.
358 * @member: the name of the list_head within the struct.
360 * Note, that list is expected to be not empty.
362 #define list_first_entry(ptr, type, member) \
363 list_entry((ptr)->next, type, member)
366 * list_last_entry - get the last element from a list
367 * @ptr: the list head to take the element from.
368 * @type: the type of the struct this is embedded in.
369 * @member: the name of the list_head within the struct.
371 * Note, that list is expected to be not empty.
373 #define list_last_entry(ptr, type, member) \
374 list_entry((ptr)->prev, type, member)
377 * list_first_entry_or_null - get the first element from a list
378 * @ptr: the list head to take the element from.
379 * @type: the type of the struct this is embedded in.
380 * @member: the name of the list_head within the struct.
382 * Note that if the list is empty, it returns NULL.
384 #define list_first_entry_or_null(ptr, type, member) \
385 (!list_empty(ptr) ? list_first_entry(ptr, type, member) : NULL)
388 * list_next_entry - get the next element in list
389 * @pos: the type * to cursor
390 * @member: the name of the list_head within the struct.
392 #define list_next_entry(pos, member) \
393 list_entry((pos)->member.next, typeof(*(pos)), member)
396 * list_prev_entry - get the prev element in list
397 * @pos: the type * to cursor
398 * @member: the name of the list_head within the struct.
400 #define list_prev_entry(pos, member) \
401 list_entry((pos)->member.prev, typeof(*(pos)), member)
404 * list_for_each - iterate over a list
405 * @pos: the &struct list_head to use as a loop cursor.
406 * @head: the head for your list.
408 #define list_for_each(pos, head) \
409 for (pos = (head)->next; pos != (head); pos = pos->next)
412 * list_for_each_prev - iterate over a list backwards
413 * @pos: the &struct list_head to use as a loop cursor.
414 * @head: the head for your list.
416 #define list_for_each_prev(pos, head) \
417 for (pos = (head)->prev; pos != (head); pos = pos->prev)
420 * list_for_each_safe - iterate over a list safe against removal of list entry
421 * @pos: the &struct list_head to use as a loop cursor.
422 * @n: another &struct list_head to use as temporary storage
423 * @head: the head for your list.
425 #define list_for_each_safe(pos, n, head) \
426 for (pos = (head)->next, n = pos->next; pos != (head); \
427 pos = n, n = pos->next)
430 * list_for_each_prev_safe - iterate over a list backwards safe against removal of list entry
431 * @pos: the &struct list_head to use as a loop cursor.
432 * @n: another &struct list_head to use as temporary storage
433 * @head: the head for your list.
435 #define list_for_each_prev_safe(pos, n, head) \
436 for (pos = (head)->prev, n = pos->prev; \
438 pos = n, n = pos->prev)
441 * list_for_each_entry - iterate over list of given type
442 * @pos: the type * to use as a loop cursor.
443 * @head: the head for your list.
444 * @member: the name of the list_head within the struct.
446 #define list_for_each_entry(pos, head, member) \
447 for (pos = list_first_entry(head, typeof(*pos), member); \
448 &pos->member != (head); \
449 pos = list_next_entry(pos, member))
452 * list_for_each_entry_reverse - iterate backwards over list of given type.
453 * @pos: the type * to use as a loop cursor.
454 * @head: the head for your list.
455 * @member: the name of the list_head within the struct.
457 #define list_for_each_entry_reverse(pos, head, member) \
458 for (pos = list_last_entry(head, typeof(*pos), member); \
459 &pos->member != (head); \
460 pos = list_prev_entry(pos, member))
463 * list_prepare_entry - prepare a pos entry for use in list_for_each_entry_continue()
464 * @pos: the type * to use as a start point
465 * @head: the head of the list
466 * @member: the name of the list_head within the struct.
468 * Prepares a pos entry for use as a start point in list_for_each_entry_continue().
470 #define list_prepare_entry(pos, head, member) \
471 ((pos) ? : list_entry(head, typeof(*pos), member))
474 * list_for_each_entry_continue - continue iteration over list of given type
475 * @pos: the type * to use as a loop cursor.
476 * @head: the head for your list.
477 * @member: the name of the list_head within the struct.
479 * Continue to iterate over list of given type, continuing after
480 * the current position.
482 #define list_for_each_entry_continue(pos, head, member) \
483 for (pos = list_next_entry(pos, member); \
484 &pos->member != (head); \
485 pos = list_next_entry(pos, member))
488 * list_for_each_entry_continue_reverse - iterate backwards from the given point
489 * @pos: the type * to use as a loop cursor.
490 * @head: the head for your list.
491 * @member: the name of the list_head within the struct.
493 * Start to iterate over list of given type backwards, continuing after
494 * the current position.
496 #define list_for_each_entry_continue_reverse(pos, head, member) \
497 for (pos = list_prev_entry(pos, member); \
498 &pos->member != (head); \
499 pos = list_prev_entry(pos, member))
502 * list_for_each_entry_from - iterate over list of given type from the current point
503 * @pos: the type * to use as a loop cursor.
504 * @head: the head for your list.
505 * @member: the name of the list_head within the struct.
507 * Iterate over list of given type, continuing from current position.
509 #define list_for_each_entry_from(pos, head, member) \
510 for (; &pos->member != (head); \
511 pos = list_next_entry(pos, member))
514 * list_for_each_entry_safe - iterate over list of given type safe against removal of list entry
515 * @pos: the type * to use as a loop cursor.
516 * @n: another type * to use as temporary storage
517 * @head: the head for your list.
518 * @member: the name of the list_head within the struct.
520 #define list_for_each_entry_safe(pos, n, head, member) \
521 for (pos = list_first_entry(head, typeof(*pos), member), \
522 n = list_next_entry(pos, member); \
523 &pos->member != (head); \
524 pos = n, n = list_next_entry(n, member))
527 * list_for_each_entry_safe_continue - continue list iteration safe against removal
528 * @pos: the type * to use as a loop cursor.
529 * @n: another type * to use as temporary storage
530 * @head: the head for your list.
531 * @member: the name of the list_head within the struct.
533 * Iterate over list of given type, continuing after current point,
534 * safe against removal of list entry.
536 #define list_for_each_entry_safe_continue(pos, n, head, member) \
537 for (pos = list_next_entry(pos, member), \
538 n = list_next_entry(pos, member); \
539 &pos->member != (head); \
540 pos = n, n = list_next_entry(n, member))
543 * list_for_each_entry_safe_from - iterate over list from current point safe against removal
544 * @pos: the type * to use as a loop cursor.
545 * @n: another type * to use as temporary storage
546 * @head: the head for your list.
547 * @member: the name of the list_head within the struct.
549 * Iterate over list of given type from current point, safe against
550 * removal of list entry.
552 #define list_for_each_entry_safe_from(pos, n, head, member) \
553 for (n = list_next_entry(pos, member); \
554 &pos->member != (head); \
555 pos = n, n = list_next_entry(n, member))
558 * list_for_each_entry_safe_reverse - iterate backwards over list safe against removal
559 * @pos: the type * to use as a loop cursor.
560 * @n: another type * to use as temporary storage
561 * @head: the head for your list.
562 * @member: the name of the list_head within the struct.
564 * Iterate backwards over list of given type, safe against removal
567 #define list_for_each_entry_safe_reverse(pos, n, head, member) \
568 for (pos = list_last_entry(head, typeof(*pos), member), \
569 n = list_prev_entry(pos, member); \
570 &pos->member != (head); \
571 pos = n, n = list_prev_entry(n, member))
574 * list_safe_reset_next - reset a stale list_for_each_entry_safe loop
575 * @pos: the loop cursor used in the list_for_each_entry_safe loop
576 * @n: temporary storage used in list_for_each_entry_safe
577 * @member: the name of the list_head within the struct.
579 * list_safe_reset_next is not safe to use in general if the list may be
580 * modified concurrently (eg. the lock is dropped in the loop body). An
581 * exception to this is if the cursor element (pos) is pinned in the list,
582 * and list_safe_reset_next is called after re-taking the lock and before
583 * completing the current iteration of the loop body.
585 #define list_safe_reset_next(pos, n, member) \
586 n = list_next_entry(pos, member)
589 * Double linked lists with a single pointer list head.
590 * Mostly useful for hash tables where the two pointer list head is
592 * You lose the ability to access the tail in O(1).
595 #define HLIST_HEAD_INIT { .first = NULL }
596 #define HLIST_HEAD(name) struct hlist_head name = { .first = NULL }
597 #define INIT_HLIST_HEAD(ptr) ((ptr)->first = NULL)
598 static inline void INIT_HLIST_NODE(struct hlist_node
*h
)
604 static inline int hlist_unhashed(const struct hlist_node
*h
)
609 static inline int hlist_empty(const struct hlist_head
*h
)
611 return !READ_ONCE(h
->first
);
614 static inline void __hlist_del(struct hlist_node
*n
)
616 struct hlist_node
*next
= n
->next
;
617 struct hlist_node
**pprev
= n
->pprev
;
619 WRITE_ONCE(*pprev
, next
);
624 static inline void hlist_del(struct hlist_node
*n
)
627 n
->next
= LIST_POISON1
;
628 n
->pprev
= LIST_POISON2
;
631 static inline void hlist_del_init(struct hlist_node
*n
)
633 if (!hlist_unhashed(n
)) {
639 static inline void hlist_add_head(struct hlist_node
*n
, struct hlist_head
*h
)
641 struct hlist_node
*first
= h
->first
;
644 first
->pprev
= &n
->next
;
645 WRITE_ONCE(h
->first
, n
);
646 n
->pprev
= &h
->first
;
649 /* next must be != NULL */
650 static inline void hlist_add_before(struct hlist_node
*n
,
651 struct hlist_node
*next
)
653 n
->pprev
= next
->pprev
;
655 next
->pprev
= &n
->next
;
656 WRITE_ONCE(*(n
->pprev
), n
);
659 static inline void hlist_add_behind(struct hlist_node
*n
,
660 struct hlist_node
*prev
)
662 n
->next
= prev
->next
;
663 WRITE_ONCE(prev
->next
, n
);
664 n
->pprev
= &prev
->next
;
667 n
->next
->pprev
= &n
->next
;
670 /* after that we'll appear to be on some hlist and hlist_del will work */
671 static inline void hlist_add_fake(struct hlist_node
*n
)
676 static inline bool hlist_fake(struct hlist_node
*h
)
678 return h
->pprev
== &h
->next
;
682 * Move a list from one list head to another. Fixup the pprev
683 * reference of the first entry if it exists.
685 static inline void hlist_move_list(struct hlist_head
*old
,
686 struct hlist_head
*new)
688 new->first
= old
->first
;
690 new->first
->pprev
= &new->first
;
694 #define hlist_entry(ptr, type, member) container_of(ptr,type,member)
696 #define hlist_for_each(pos, head) \
697 for (pos = (head)->first; pos ; pos = pos->next)
699 #define hlist_for_each_safe(pos, n, head) \
700 for (pos = (head)->first; pos && ({ n = pos->next; 1; }); \
703 #define hlist_entry_safe(ptr, type, member) \
704 ({ typeof(ptr) ____ptr = (ptr); \
705 ____ptr ? hlist_entry(____ptr, type, member) : NULL; \
709 * hlist_for_each_entry - iterate over list of given type
710 * @pos: the type * to use as a loop cursor.
711 * @head: the head for your list.
712 * @member: the name of the hlist_node within the struct.
714 #define hlist_for_each_entry(pos, head, member) \
715 for (pos = hlist_entry_safe((head)->first, typeof(*(pos)), member);\
717 pos = hlist_entry_safe((pos)->member.next, typeof(*(pos)), member))
720 * hlist_for_each_entry_continue - iterate over a hlist continuing after current point
721 * @pos: the type * to use as a loop cursor.
722 * @member: the name of the hlist_node within the struct.
724 #define hlist_for_each_entry_continue(pos, member) \
725 for (pos = hlist_entry_safe((pos)->member.next, typeof(*(pos)), member);\
727 pos = hlist_entry_safe((pos)->member.next, typeof(*(pos)), member))
730 * hlist_for_each_entry_from - iterate over a hlist continuing from current point
731 * @pos: the type * to use as a loop cursor.
732 * @member: the name of the hlist_node within the struct.
734 #define hlist_for_each_entry_from(pos, member) \
736 pos = hlist_entry_safe((pos)->member.next, typeof(*(pos)), member))
739 * hlist_for_each_entry_safe - iterate over list of given type safe against removal of list entry
740 * @pos: the type * to use as a loop cursor.
741 * @n: another &struct hlist_node to use as temporary storage
742 * @head: the head for your list.
743 * @member: the name of the hlist_node within the struct.
745 #define hlist_for_each_entry_safe(pos, n, head, member) \
746 for (pos = hlist_entry_safe((head)->first, typeof(*pos), member);\
747 pos && ({ n = pos->member.next; 1; }); \
748 pos = hlist_entry_safe(n, typeof(*pos), member))