]>
git.proxmox.com Git - mirror_ubuntu-bionic-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
);
31 #ifdef CONFIG_DEBUG_LIST
32 extern bool __list_add_valid(struct list_head
*new,
33 struct list_head
*prev
,
34 struct list_head
*next
);
35 extern bool __list_del_entry_valid(struct list_head
*entry
);
37 static inline bool __list_add_valid(struct list_head
*new,
38 struct list_head
*prev
,
39 struct list_head
*next
)
43 static inline bool __list_del_entry_valid(struct list_head
*entry
)
50 * Insert a new entry between two known consecutive entries.
52 * This is only for internal list manipulation where we know
53 * the prev/next entries already!
55 static inline void __list_add(struct list_head
*new,
56 struct list_head
*prev
,
57 struct list_head
*next
)
59 if (!__list_add_valid(new, prev
, next
))
65 WRITE_ONCE(prev
->next
, new);
69 * list_add - add a new entry
70 * @new: new entry to be added
71 * @head: list head to add it after
73 * Insert a new entry after the specified head.
74 * This is good for implementing stacks.
76 static inline void list_add(struct list_head
*new, struct list_head
*head
)
78 __list_add(new, head
, head
->next
);
83 * list_add_tail - add a new entry
84 * @new: new entry to be added
85 * @head: list head to add it before
87 * Insert a new entry before the specified head.
88 * This is useful for implementing queues.
90 static inline void list_add_tail(struct list_head
*new, struct list_head
*head
)
92 __list_add(new, head
->prev
, head
);
96 * Delete a list entry by making the prev/next entries
97 * point to each other.
99 * This is only for internal list manipulation where we know
100 * the prev/next entries already!
102 static inline void __list_del(struct list_head
* prev
, struct list_head
* next
)
105 WRITE_ONCE(prev
->next
, next
);
109 * list_del - deletes entry from list.
110 * @entry: the element to delete from the list.
111 * Note: list_empty() on entry does not return true after this, the entry is
112 * in an undefined state.
114 static inline void __list_del_entry(struct list_head
*entry
)
116 if (!__list_del_entry_valid(entry
))
119 __list_del(entry
->prev
, entry
->next
);
122 static inline void list_del(struct list_head
*entry
)
124 __list_del_entry(entry
);
125 entry
->next
= LIST_POISON1
;
126 entry
->prev
= LIST_POISON2
;
130 * list_replace - replace old entry by new one
131 * @old : the element to be replaced
132 * @new : the new element to insert
134 * If @old was empty, it will be overwritten.
136 static inline void list_replace(struct list_head
*old
,
137 struct list_head
*new)
139 new->next
= old
->next
;
140 new->next
->prev
= new;
141 new->prev
= old
->prev
;
142 new->prev
->next
= new;
145 static inline void list_replace_init(struct list_head
*old
,
146 struct list_head
*new)
148 list_replace(old
, new);
153 * list_del_init - deletes entry from list and reinitialize it.
154 * @entry: the element to delete from the list.
156 static inline void list_del_init(struct list_head
*entry
)
158 __list_del_entry(entry
);
159 INIT_LIST_HEAD(entry
);
163 * list_move - delete from one list and add as another's head
164 * @list: the entry to move
165 * @head: the head that will precede our entry
167 static inline void list_move(struct list_head
*list
, struct list_head
*head
)
169 __list_del_entry(list
);
170 list_add(list
, head
);
174 * list_move_tail - delete from one list and add as another's tail
175 * @list: the entry to move
176 * @head: the head that will follow our entry
178 static inline void list_move_tail(struct list_head
*list
,
179 struct list_head
*head
)
181 __list_del_entry(list
);
182 list_add_tail(list
, head
);
186 * list_is_last - tests whether @list is the last entry in list @head
187 * @list: the entry to test
188 * @head: the head of the list
190 static inline int list_is_last(const struct list_head
*list
,
191 const struct list_head
*head
)
193 return list
->next
== head
;
197 * list_empty - tests whether a list is empty
198 * @head: the list to test.
200 static inline int list_empty(const struct list_head
*head
)
202 return READ_ONCE(head
->next
) == head
;
206 * list_empty_careful - tests whether a list is empty and not being modified
207 * @head: the list to test
210 * tests whether a list is empty _and_ checks that no other CPU might be
211 * in the process of modifying either member (next or prev)
213 * NOTE: using list_empty_careful() without synchronization
214 * can only be safe if the only activity that can happen
215 * to the list entry is list_del_init(). Eg. it cannot be used
216 * if another CPU could re-list_add() it.
218 static inline int list_empty_careful(const struct list_head
*head
)
220 struct list_head
*next
= head
->next
;
221 return (next
== head
) && (next
== head
->prev
);
225 * list_rotate_left - rotate the list to the left
226 * @head: the head of the list
228 static inline void list_rotate_left(struct list_head
*head
)
230 struct list_head
*first
;
232 if (!list_empty(head
)) {
234 list_move_tail(first
, head
);
239 * list_is_singular - tests whether a list has just one entry.
240 * @head: the list to test.
242 static inline int list_is_singular(const struct list_head
*head
)
244 return !list_empty(head
) && (head
->next
== head
->prev
);
247 static inline void __list_cut_position(struct list_head
*list
,
248 struct list_head
*head
, struct list_head
*entry
)
250 struct list_head
*new_first
= entry
->next
;
251 list
->next
= head
->next
;
252 list
->next
->prev
= list
;
255 head
->next
= new_first
;
256 new_first
->prev
= head
;
260 * list_cut_position - cut a list into two
261 * @list: a new list to add all removed entries
262 * @head: a list with entries
263 * @entry: an entry within head, could be the head itself
264 * and if so we won't cut the list
266 * This helper moves the initial part of @head, up to and
267 * including @entry, from @head to @list. You should
268 * pass on @entry an element you know is on @head. @list
269 * should be an empty list or a list you do not care about
273 static inline void list_cut_position(struct list_head
*list
,
274 struct list_head
*head
, struct list_head
*entry
)
276 if (list_empty(head
))
278 if (list_is_singular(head
) &&
279 (head
->next
!= entry
&& head
!= entry
))
282 INIT_LIST_HEAD(list
);
284 __list_cut_position(list
, head
, entry
);
287 static inline void __list_splice(const struct list_head
*list
,
288 struct list_head
*prev
,
289 struct list_head
*next
)
291 struct list_head
*first
= list
->next
;
292 struct list_head
*last
= list
->prev
;
302 * list_splice - join two lists, this is designed for stacks
303 * @list: the new list to add.
304 * @head: the place to add it in the first list.
306 static inline void list_splice(const struct list_head
*list
,
307 struct list_head
*head
)
309 if (!list_empty(list
))
310 __list_splice(list
, head
, head
->next
);
314 * list_splice_tail - join two lists, each list being a queue
315 * @list: the new list to add.
316 * @head: the place to add it in the first list.
318 static inline void list_splice_tail(struct list_head
*list
,
319 struct list_head
*head
)
321 if (!list_empty(list
))
322 __list_splice(list
, head
->prev
, head
);
326 * list_splice_init - join two lists and reinitialise the emptied list.
327 * @list: the new list to add.
328 * @head: the place to add it in the first list.
330 * The list at @list is reinitialised
332 static inline void list_splice_init(struct list_head
*list
,
333 struct list_head
*head
)
335 if (!list_empty(list
)) {
336 __list_splice(list
, head
, head
->next
);
337 INIT_LIST_HEAD(list
);
342 * list_splice_tail_init - join two lists and reinitialise the emptied list
343 * @list: the new list to add.
344 * @head: the place to add it in the first list.
346 * Each of the lists is a queue.
347 * The list at @list is reinitialised
349 static inline void list_splice_tail_init(struct list_head
*list
,
350 struct list_head
*head
)
352 if (!list_empty(list
)) {
353 __list_splice(list
, head
->prev
, head
);
354 INIT_LIST_HEAD(list
);
359 * list_entry - get the struct for this entry
360 * @ptr: the &struct list_head pointer.
361 * @type: the type of the struct this is embedded in.
362 * @member: the name of the list_head within the struct.
364 #define list_entry(ptr, type, member) \
365 container_of(ptr, type, member)
368 * list_first_entry - get the first element from a list
369 * @ptr: the list head to take the element from.
370 * @type: the type of the struct this is embedded in.
371 * @member: the name of the list_head within the struct.
373 * Note, that list is expected to be not empty.
375 #define list_first_entry(ptr, type, member) \
376 list_entry((ptr)->next, type, member)
379 * list_last_entry - get the last element from a list
380 * @ptr: the list head to take the element from.
381 * @type: the type of the struct this is embedded in.
382 * @member: the name of the list_head within the struct.
384 * Note, that list is expected to be not empty.
386 #define list_last_entry(ptr, type, member) \
387 list_entry((ptr)->prev, type, member)
390 * list_first_entry_or_null - get the first element from a list
391 * @ptr: the list head to take the element from.
392 * @type: the type of the struct this is embedded in.
393 * @member: the name of the list_head within the struct.
395 * Note that if the list is empty, it returns NULL.
397 #define list_first_entry_or_null(ptr, type, member) ({ \
398 struct list_head *head__ = (ptr); \
399 struct list_head *pos__ = READ_ONCE(head__->next); \
400 pos__ != head__ ? list_entry(pos__, type, member) : NULL; \
404 * list_next_entry - get the next element in list
405 * @pos: the type * to cursor
406 * @member: the name of the list_head within the struct.
408 #define list_next_entry(pos, member) \
409 list_entry((pos)->member.next, typeof(*(pos)), member)
412 * list_prev_entry - get the prev element in list
413 * @pos: the type * to cursor
414 * @member: the name of the list_head within the struct.
416 #define list_prev_entry(pos, member) \
417 list_entry((pos)->member.prev, typeof(*(pos)), member)
420 * list_for_each - iterate over a list
421 * @pos: the &struct list_head to use as a loop cursor.
422 * @head: the head for your list.
424 #define list_for_each(pos, head) \
425 for (pos = (head)->next; pos != (head); pos = pos->next)
428 * list_for_each_prev - iterate over a list backwards
429 * @pos: the &struct list_head to use as a loop cursor.
430 * @head: the head for your list.
432 #define list_for_each_prev(pos, head) \
433 for (pos = (head)->prev; pos != (head); pos = pos->prev)
436 * list_for_each_safe - iterate over a list safe against removal of list entry
437 * @pos: the &struct list_head to use as a loop cursor.
438 * @n: another &struct list_head to use as temporary storage
439 * @head: the head for your list.
441 #define list_for_each_safe(pos, n, head) \
442 for (pos = (head)->next, n = pos->next; pos != (head); \
443 pos = n, n = pos->next)
446 * list_for_each_prev_safe - iterate over a list backwards safe against removal of list entry
447 * @pos: the &struct list_head to use as a loop cursor.
448 * @n: another &struct list_head to use as temporary storage
449 * @head: the head for your list.
451 #define list_for_each_prev_safe(pos, n, head) \
452 for (pos = (head)->prev, n = pos->prev; \
454 pos = n, n = pos->prev)
457 * list_for_each_entry - iterate 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_head within the struct.
462 #define list_for_each_entry(pos, head, member) \
463 for (pos = list_first_entry(head, typeof(*pos), member); \
464 &pos->member != (head); \
465 pos = list_next_entry(pos, member))
468 * list_for_each_entry_reverse - iterate backwards over list of given type.
469 * @pos: the type * to use as a loop cursor.
470 * @head: the head for your list.
471 * @member: the name of the list_head within the struct.
473 #define list_for_each_entry_reverse(pos, head, member) \
474 for (pos = list_last_entry(head, typeof(*pos), member); \
475 &pos->member != (head); \
476 pos = list_prev_entry(pos, member))
479 * list_prepare_entry - prepare a pos entry for use in list_for_each_entry_continue()
480 * @pos: the type * to use as a start point
481 * @head: the head of the list
482 * @member: the name of the list_head within the struct.
484 * Prepares a pos entry for use as a start point in list_for_each_entry_continue().
486 #define list_prepare_entry(pos, head, member) \
487 ((pos) ? : list_entry(head, typeof(*pos), member))
490 * list_for_each_entry_continue - continue iteration over list of given type
491 * @pos: the type * to use as a loop cursor.
492 * @head: the head for your list.
493 * @member: the name of the list_head within the struct.
495 * Continue to iterate over list of given type, continuing after
496 * the current position.
498 #define list_for_each_entry_continue(pos, head, member) \
499 for (pos = list_next_entry(pos, member); \
500 &pos->member != (head); \
501 pos = list_next_entry(pos, member))
504 * list_for_each_entry_continue_reverse - iterate backwards from the given point
505 * @pos: the type * to use as a loop cursor.
506 * @head: the head for your list.
507 * @member: the name of the list_head within the struct.
509 * Start to iterate over list of given type backwards, continuing after
510 * the current position.
512 #define list_for_each_entry_continue_reverse(pos, head, member) \
513 for (pos = list_prev_entry(pos, member); \
514 &pos->member != (head); \
515 pos = list_prev_entry(pos, member))
518 * list_for_each_entry_from - iterate over list of given type from the current point
519 * @pos: the type * to use as a loop cursor.
520 * @head: the head for your list.
521 * @member: the name of the list_head within the struct.
523 * Iterate over list of given type, continuing from current position.
525 #define list_for_each_entry_from(pos, head, member) \
526 for (; &pos->member != (head); \
527 pos = list_next_entry(pos, member))
530 * list_for_each_entry_safe - iterate over list of given type safe against removal of list entry
531 * @pos: the type * to use as a loop cursor.
532 * @n: another type * to use as temporary storage
533 * @head: the head for your list.
534 * @member: the name of the list_head within the struct.
536 #define list_for_each_entry_safe(pos, n, head, member) \
537 for (pos = list_first_entry(head, typeof(*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_continue - continue list iteration 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, continuing after current point,
550 * safe against removal of list entry.
552 #define list_for_each_entry_safe_continue(pos, n, head, member) \
553 for (pos = list_next_entry(pos, member), \
554 n = list_next_entry(pos, member); \
555 &pos->member != (head); \
556 pos = n, n = list_next_entry(n, member))
559 * list_for_each_entry_safe_from - iterate over list from current point safe against removal
560 * @pos: the type * to use as a loop cursor.
561 * @n: another type * to use as temporary storage
562 * @head: the head for your list.
563 * @member: the name of the list_head within the struct.
565 * Iterate over list of given type from current point, safe against
566 * removal of list entry.
568 #define list_for_each_entry_safe_from(pos, n, head, member) \
569 for (n = list_next_entry(pos, member); \
570 &pos->member != (head); \
571 pos = n, n = list_next_entry(n, member))
574 * list_for_each_entry_safe_reverse - iterate backwards over list safe against removal
575 * @pos: the type * to use as a loop cursor.
576 * @n: another type * to use as temporary storage
577 * @head: the head for your list.
578 * @member: the name of the list_head within the struct.
580 * Iterate backwards over list of given type, safe against removal
583 #define list_for_each_entry_safe_reverse(pos, n, head, member) \
584 for (pos = list_last_entry(head, typeof(*pos), member), \
585 n = list_prev_entry(pos, member); \
586 &pos->member != (head); \
587 pos = n, n = list_prev_entry(n, member))
590 * list_safe_reset_next - reset a stale list_for_each_entry_safe loop
591 * @pos: the loop cursor used in the list_for_each_entry_safe loop
592 * @n: temporary storage used in list_for_each_entry_safe
593 * @member: the name of the list_head within the struct.
595 * list_safe_reset_next is not safe to use in general if the list may be
596 * modified concurrently (eg. the lock is dropped in the loop body). An
597 * exception to this is if the cursor element (pos) is pinned in the list,
598 * and list_safe_reset_next is called after re-taking the lock and before
599 * completing the current iteration of the loop body.
601 #define list_safe_reset_next(pos, n, member) \
602 n = list_next_entry(pos, member)
605 * Double linked lists with a single pointer list head.
606 * Mostly useful for hash tables where the two pointer list head is
608 * You lose the ability to access the tail in O(1).
611 #define HLIST_HEAD_INIT { .first = NULL }
612 #define HLIST_HEAD(name) struct hlist_head name = { .first = NULL }
613 #define INIT_HLIST_HEAD(ptr) ((ptr)->first = NULL)
614 static inline void INIT_HLIST_NODE(struct hlist_node
*h
)
620 static inline int hlist_unhashed(const struct hlist_node
*h
)
625 static inline int hlist_empty(const struct hlist_head
*h
)
627 return !READ_ONCE(h
->first
);
630 static inline void __hlist_del(struct hlist_node
*n
)
632 struct hlist_node
*next
= n
->next
;
633 struct hlist_node
**pprev
= n
->pprev
;
635 WRITE_ONCE(*pprev
, next
);
640 static inline void hlist_del(struct hlist_node
*n
)
643 n
->next
= LIST_POISON1
;
644 n
->pprev
= LIST_POISON2
;
647 static inline void hlist_del_init(struct hlist_node
*n
)
649 if (!hlist_unhashed(n
)) {
655 static inline void hlist_add_head(struct hlist_node
*n
, struct hlist_head
*h
)
657 struct hlist_node
*first
= h
->first
;
660 first
->pprev
= &n
->next
;
661 WRITE_ONCE(h
->first
, n
);
662 n
->pprev
= &h
->first
;
665 /* next must be != NULL */
666 static inline void hlist_add_before(struct hlist_node
*n
,
667 struct hlist_node
*next
)
669 n
->pprev
= next
->pprev
;
671 next
->pprev
= &n
->next
;
672 WRITE_ONCE(*(n
->pprev
), n
);
675 static inline void hlist_add_behind(struct hlist_node
*n
,
676 struct hlist_node
*prev
)
678 n
->next
= prev
->next
;
679 WRITE_ONCE(prev
->next
, n
);
680 n
->pprev
= &prev
->next
;
683 n
->next
->pprev
= &n
->next
;
686 /* after that we'll appear to be on some hlist and hlist_del will work */
687 static inline void hlist_add_fake(struct hlist_node
*n
)
692 static inline bool hlist_fake(struct hlist_node
*h
)
694 return h
->pprev
== &h
->next
;
698 * Check whether the node is the only node of the head without
702 hlist_is_singular_node(struct hlist_node
*n
, struct hlist_head
*h
)
704 return !n
->next
&& n
->pprev
== &h
->first
;
708 * Move a list from one list head to another. Fixup the pprev
709 * reference of the first entry if it exists.
711 static inline void hlist_move_list(struct hlist_head
*old
,
712 struct hlist_head
*new)
714 new->first
= old
->first
;
716 new->first
->pprev
= &new->first
;
720 #define hlist_entry(ptr, type, member) container_of(ptr,type,member)
722 #define hlist_for_each(pos, head) \
723 for (pos = (head)->first; pos ; pos = pos->next)
725 #define hlist_for_each_safe(pos, n, head) \
726 for (pos = (head)->first; pos && ({ n = pos->next; 1; }); \
729 #define hlist_entry_safe(ptr, type, member) \
730 ({ typeof(ptr) ____ptr = (ptr); \
731 ____ptr ? hlist_entry(____ptr, type, member) : NULL; \
735 * hlist_for_each_entry - iterate over list of given type
736 * @pos: the type * to use as a loop cursor.
737 * @head: the head for your list.
738 * @member: the name of the hlist_node within the struct.
740 #define hlist_for_each_entry(pos, head, member) \
741 for (pos = hlist_entry_safe((head)->first, typeof(*(pos)), member);\
743 pos = hlist_entry_safe((pos)->member.next, typeof(*(pos)), member))
746 * hlist_for_each_entry_continue - iterate over a hlist continuing after current point
747 * @pos: the type * to use as a loop cursor.
748 * @member: the name of the hlist_node within the struct.
750 #define hlist_for_each_entry_continue(pos, member) \
751 for (pos = hlist_entry_safe((pos)->member.next, typeof(*(pos)), member);\
753 pos = hlist_entry_safe((pos)->member.next, typeof(*(pos)), member))
756 * hlist_for_each_entry_from - iterate over a hlist continuing from current point
757 * @pos: the type * to use as a loop cursor.
758 * @member: the name of the hlist_node within the struct.
760 #define hlist_for_each_entry_from(pos, member) \
762 pos = hlist_entry_safe((pos)->member.next, typeof(*(pos)), member))
765 * hlist_for_each_entry_safe - iterate over list of given type safe against removal of list entry
766 * @pos: the type * to use as a loop cursor.
767 * @n: another &struct hlist_node to use as temporary storage
768 * @head: the head for your list.
769 * @member: the name of the hlist_node within the struct.
771 #define hlist_for_each_entry_safe(pos, n, head, member) \
772 for (pos = hlist_entry_safe((head)->first, typeof(*pos), member);\
773 pos && ({ n = pos->member.next; 1; }); \
774 pos = hlist_entry_safe(n, typeof(*pos), member))