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1 /* SPDX-License-Identifier: GPL-2.0 */
5 #include <linux/types.h>
6 #include <linux/stddef.h>
7 #include <linux/poison.h>
8 #include <linux/const.h>
9 #include <linux/kernel.h>
12 * Circular doubly linked list implementation.
14 * Some of the internal functions ("__xxx") are useful when
15 * manipulating whole lists rather than single entries, as
16 * sometimes we already know the next/prev entries and we can
17 * generate better code by using them directly rather than
18 * using the generic single-entry routines.
21 #define LIST_HEAD_INIT(name) { &(name), &(name) }
23 #define LIST_HEAD(name) \
24 struct list_head name = LIST_HEAD_INIT(name)
27 * INIT_LIST_HEAD - Initialize a list_head structure
28 * @list: list_head structure to be initialized.
30 * Initializes the list_head to point to itself. If it is a list header,
31 * the result is an empty list.
33 static inline void INIT_LIST_HEAD(struct list_head
*list
)
35 WRITE_ONCE(list
->next
, list
);
39 #ifdef CONFIG_DEBUG_LIST
40 extern bool __list_add_valid(struct list_head
*new,
41 struct list_head
*prev
,
42 struct list_head
*next
);
43 extern bool __list_del_entry_valid(struct list_head
*entry
);
45 static inline bool __list_add_valid(struct list_head
*new,
46 struct list_head
*prev
,
47 struct list_head
*next
)
51 static inline bool __list_del_entry_valid(struct list_head
*entry
)
58 * Insert a new entry between two known consecutive entries.
60 * This is only for internal list manipulation where we know
61 * the prev/next entries already!
63 static inline void __list_add(struct list_head
*new,
64 struct list_head
*prev
,
65 struct list_head
*next
)
67 if (!__list_add_valid(new, prev
, next
))
73 WRITE_ONCE(prev
->next
, new);
77 * list_add - add a new entry
78 * @new: new entry to be added
79 * @head: list head to add it after
81 * Insert a new entry after the specified head.
82 * This is good for implementing stacks.
84 static inline void list_add(struct list_head
*new, struct list_head
*head
)
86 __list_add(new, head
, head
->next
);
91 * list_add_tail - add a new entry
92 * @new: new entry to be added
93 * @head: list head to add it before
95 * Insert a new entry before the specified head.
96 * This is useful for implementing queues.
98 static inline void list_add_tail(struct list_head
*new, struct list_head
*head
)
100 __list_add(new, head
->prev
, head
);
104 * Delete a list entry by making the prev/next entries
105 * point to each other.
107 * This is only for internal list manipulation where we know
108 * the prev/next entries already!
110 static inline void __list_del(struct list_head
* prev
, struct list_head
* next
)
113 WRITE_ONCE(prev
->next
, next
);
117 * Delete a list entry and clear the 'prev' pointer.
119 * This is a special-purpose list clearing method used in the networking code
120 * for lists allocated as per-cpu, where we don't want to incur the extra
121 * WRITE_ONCE() overhead of a regular list_del_init(). The code that uses this
122 * needs to check the node 'prev' pointer instead of calling list_empty().
124 static inline void __list_del_clearprev(struct list_head
*entry
)
126 __list_del(entry
->prev
, entry
->next
);
130 static inline void __list_del_entry(struct list_head
*entry
)
132 if (!__list_del_entry_valid(entry
))
135 __list_del(entry
->prev
, entry
->next
);
139 * list_del - deletes entry from list.
140 * @entry: the element to delete from the list.
141 * Note: list_empty() on entry does not return true after this, the entry is
142 * in an undefined state.
144 static inline void list_del(struct list_head
*entry
)
146 __list_del_entry(entry
);
147 entry
->next
= LIST_POISON1
;
148 entry
->prev
= LIST_POISON2
;
152 * list_replace - replace old entry by new one
153 * @old : the element to be replaced
154 * @new : the new element to insert
156 * If @old was empty, it will be overwritten.
158 static inline void list_replace(struct list_head
*old
,
159 struct list_head
*new)
161 new->next
= old
->next
;
162 new->next
->prev
= new;
163 new->prev
= old
->prev
;
164 new->prev
->next
= new;
168 * list_replace_init - replace old entry by new one and initialize the old one
169 * @old : the element to be replaced
170 * @new : the new element to insert
172 * If @old was empty, it will be overwritten.
174 static inline void list_replace_init(struct list_head
*old
,
175 struct list_head
*new)
177 list_replace(old
, new);
182 * list_swap - replace entry1 with entry2 and re-add entry1 at entry2's position
183 * @entry1: the location to place entry2
184 * @entry2: the location to place entry1
186 static inline void list_swap(struct list_head
*entry1
,
187 struct list_head
*entry2
)
189 struct list_head
*pos
= entry2
->prev
;
192 list_replace(entry1
, entry2
);
195 list_add(entry1
, pos
);
199 * list_del_init - deletes entry from list and reinitialize it.
200 * @entry: the element to delete from the list.
202 static inline void list_del_init(struct list_head
*entry
)
204 __list_del_entry(entry
);
205 INIT_LIST_HEAD(entry
);
209 * list_move - delete from one list and add as another's head
210 * @list: the entry to move
211 * @head: the head that will precede our entry
213 static inline void list_move(struct list_head
*list
, struct list_head
*head
)
215 __list_del_entry(list
);
216 list_add(list
, head
);
220 * list_move_tail - delete from one list and add as another's tail
221 * @list: the entry to move
222 * @head: the head that will follow our entry
224 static inline void list_move_tail(struct list_head
*list
,
225 struct list_head
*head
)
227 __list_del_entry(list
);
228 list_add_tail(list
, head
);
232 * list_bulk_move_tail - move a subsection of a list to its tail
233 * @head: the head that will follow our entry
234 * @first: first entry to move
235 * @last: last entry to move, can be the same as first
237 * Move all entries between @first and including @last before @head.
238 * All three entries must belong to the same linked list.
240 static inline void list_bulk_move_tail(struct list_head
*head
,
241 struct list_head
*first
,
242 struct list_head
*last
)
244 first
->prev
->next
= last
->next
;
245 last
->next
->prev
= first
->prev
;
247 head
->prev
->next
= first
;
248 first
->prev
= head
->prev
;
255 * list_is_first -- tests whether @list is the first entry in list @head
256 * @list: the entry to test
257 * @head: the head of the list
259 static inline int list_is_first(const struct list_head
*list
,
260 const struct list_head
*head
)
262 return list
->prev
== head
;
266 * list_is_last - tests whether @list is the last entry in list @head
267 * @list: the entry to test
268 * @head: the head of the list
270 static inline int list_is_last(const struct list_head
*list
,
271 const struct list_head
*head
)
273 return list
->next
== head
;
277 * list_empty - tests whether a list is empty
278 * @head: the list to test.
280 static inline int list_empty(const struct list_head
*head
)
282 return READ_ONCE(head
->next
) == head
;
286 * list_del_init_careful - deletes entry from list and reinitialize it.
287 * @entry: the element to delete from the list.
289 * This is the same as list_del_init(), except designed to be used
290 * together with list_empty_careful() in a way to guarantee ordering
291 * of other memory operations.
293 * Any memory operations done before a list_del_init_careful() are
294 * guaranteed to be visible after a list_empty_careful() test.
296 static inline void list_del_init_careful(struct list_head
*entry
)
298 __list_del_entry(entry
);
300 smp_store_release(&entry
->next
, entry
);
304 * list_empty_careful - tests whether a list is empty and not being modified
305 * @head: the list to test
308 * tests whether a list is empty _and_ checks that no other CPU might be
309 * in the process of modifying either member (next or prev)
311 * NOTE: using list_empty_careful() without synchronization
312 * can only be safe if the only activity that can happen
313 * to the list entry is list_del_init(). Eg. it cannot be used
314 * if another CPU could re-list_add() it.
316 static inline int list_empty_careful(const struct list_head
*head
)
318 struct list_head
*next
= smp_load_acquire(&head
->next
);
319 return (next
== head
) && (next
== head
->prev
);
323 * list_rotate_left - rotate the list to the left
324 * @head: the head of the list
326 static inline void list_rotate_left(struct list_head
*head
)
328 struct list_head
*first
;
330 if (!list_empty(head
)) {
332 list_move_tail(first
, head
);
337 * list_rotate_to_front() - Rotate list to specific item.
338 * @list: The desired new front of the list.
339 * @head: The head of the list.
341 * Rotates list so that @list becomes the new front of the list.
343 static inline void list_rotate_to_front(struct list_head
*list
,
344 struct list_head
*head
)
347 * Deletes the list head from the list denoted by @head and
348 * places it as the tail of @list, this effectively rotates the
349 * list so that @list is at the front.
351 list_move_tail(head
, list
);
355 * list_is_singular - tests whether a list has just one entry.
356 * @head: the list to test.
358 static inline int list_is_singular(const struct list_head
*head
)
360 return !list_empty(head
) && (head
->next
== head
->prev
);
363 static inline void __list_cut_position(struct list_head
*list
,
364 struct list_head
*head
, struct list_head
*entry
)
366 struct list_head
*new_first
= entry
->next
;
367 list
->next
= head
->next
;
368 list
->next
->prev
= list
;
371 head
->next
= new_first
;
372 new_first
->prev
= head
;
376 * list_cut_position - cut a list into two
377 * @list: a new list to add all removed entries
378 * @head: a list with entries
379 * @entry: an entry within head, could be the head itself
380 * and if so we won't cut the list
382 * This helper moves the initial part of @head, up to and
383 * including @entry, from @head to @list. You should
384 * pass on @entry an element you know is on @head. @list
385 * should be an empty list or a list you do not care about
389 static inline void list_cut_position(struct list_head
*list
,
390 struct list_head
*head
, struct list_head
*entry
)
392 if (list_empty(head
))
394 if (list_is_singular(head
) &&
395 (head
->next
!= entry
&& head
!= entry
))
398 INIT_LIST_HEAD(list
);
400 __list_cut_position(list
, head
, entry
);
404 * list_cut_before - cut a list into two, before given entry
405 * @list: a new list to add all removed entries
406 * @head: a list with entries
407 * @entry: an entry within head, could be the head itself
409 * This helper moves the initial part of @head, up to but
410 * excluding @entry, from @head to @list. You should pass
411 * in @entry an element you know is on @head. @list should
412 * be an empty list or a list you do not care about losing
414 * If @entry == @head, all entries on @head are moved to
417 static inline void list_cut_before(struct list_head
*list
,
418 struct list_head
*head
,
419 struct list_head
*entry
)
421 if (head
->next
== entry
) {
422 INIT_LIST_HEAD(list
);
425 list
->next
= head
->next
;
426 list
->next
->prev
= list
;
427 list
->prev
= entry
->prev
;
428 list
->prev
->next
= list
;
433 static inline void __list_splice(const struct list_head
*list
,
434 struct list_head
*prev
,
435 struct list_head
*next
)
437 struct list_head
*first
= list
->next
;
438 struct list_head
*last
= list
->prev
;
448 * list_splice - join two lists, this is designed for stacks
449 * @list: the new list to add.
450 * @head: the place to add it in the first list.
452 static inline void list_splice(const struct list_head
*list
,
453 struct list_head
*head
)
455 if (!list_empty(list
))
456 __list_splice(list
, head
, head
->next
);
460 * list_splice_tail - join two lists, each list being a queue
461 * @list: the new list to add.
462 * @head: the place to add it in the first list.
464 static inline void list_splice_tail(struct list_head
*list
,
465 struct list_head
*head
)
467 if (!list_empty(list
))
468 __list_splice(list
, head
->prev
, head
);
472 * list_splice_init - join two lists and reinitialise the emptied list.
473 * @list: the new list to add.
474 * @head: the place to add it in the first list.
476 * The list at @list is reinitialised
478 static inline void list_splice_init(struct list_head
*list
,
479 struct list_head
*head
)
481 if (!list_empty(list
)) {
482 __list_splice(list
, head
, head
->next
);
483 INIT_LIST_HEAD(list
);
488 * list_splice_tail_init - join two lists and reinitialise the emptied list
489 * @list: the new list to add.
490 * @head: the place to add it in the first list.
492 * Each of the lists is a queue.
493 * The list at @list is reinitialised
495 static inline void list_splice_tail_init(struct list_head
*list
,
496 struct list_head
*head
)
498 if (!list_empty(list
)) {
499 __list_splice(list
, head
->prev
, head
);
500 INIT_LIST_HEAD(list
);
505 * list_entry - get the struct for this entry
506 * @ptr: the &struct list_head pointer.
507 * @type: the type of the struct this is embedded in.
508 * @member: the name of the list_head within the struct.
510 #define list_entry(ptr, type, member) \
511 container_of(ptr, type, member)
514 * list_first_entry - get the first element from a list
515 * @ptr: the list head to take the element from.
516 * @type: the type of the struct this is embedded in.
517 * @member: the name of the list_head within the struct.
519 * Note, that list is expected to be not empty.
521 #define list_first_entry(ptr, type, member) \
522 list_entry((ptr)->next, type, member)
525 * list_last_entry - get the last element from a list
526 * @ptr: the list head to take the element from.
527 * @type: the type of the struct this is embedded in.
528 * @member: the name of the list_head within the struct.
530 * Note, that list is expected to be not empty.
532 #define list_last_entry(ptr, type, member) \
533 list_entry((ptr)->prev, type, member)
536 * list_first_entry_or_null - get the first element from a list
537 * @ptr: the list head to take the element from.
538 * @type: the type of the struct this is embedded in.
539 * @member: the name of the list_head within the struct.
541 * Note that if the list is empty, it returns NULL.
543 #define list_first_entry_or_null(ptr, type, member) ({ \
544 struct list_head *head__ = (ptr); \
545 struct list_head *pos__ = READ_ONCE(head__->next); \
546 pos__ != head__ ? list_entry(pos__, type, member) : NULL; \
550 * list_next_entry - get the next element in list
551 * @pos: the type * to cursor
552 * @member: the name of the list_head within the struct.
554 #define list_next_entry(pos, member) \
555 list_entry((pos)->member.next, typeof(*(pos)), member)
558 * list_prev_entry - get the prev element in list
559 * @pos: the type * to cursor
560 * @member: the name of the list_head within the struct.
562 #define list_prev_entry(pos, member) \
563 list_entry((pos)->member.prev, typeof(*(pos)), member)
566 * list_for_each - iterate over a list
567 * @pos: the &struct list_head to use as a loop cursor.
568 * @head: the head for your list.
570 #define list_for_each(pos, head) \
571 for (pos = (head)->next; pos != (head); pos = pos->next)
574 * list_for_each_continue - continue iteration over a list
575 * @pos: the &struct list_head to use as a loop cursor.
576 * @head: the head for your list.
578 * Continue to iterate over a list, continuing after the current position.
580 #define list_for_each_continue(pos, head) \
581 for (pos = pos->next; pos != (head); pos = pos->next)
584 * list_for_each_prev - iterate over a list backwards
585 * @pos: the &struct list_head to use as a loop cursor.
586 * @head: the head for your list.
588 #define list_for_each_prev(pos, head) \
589 for (pos = (head)->prev; pos != (head); pos = pos->prev)
592 * list_for_each_safe - iterate over a list safe against removal of list entry
593 * @pos: the &struct list_head to use as a loop cursor.
594 * @n: another &struct list_head to use as temporary storage
595 * @head: the head for your list.
597 #define list_for_each_safe(pos, n, head) \
598 for (pos = (head)->next, n = pos->next; pos != (head); \
599 pos = n, n = pos->next)
602 * list_for_each_prev_safe - iterate over a list backwards safe against removal of list entry
603 * @pos: the &struct list_head to use as a loop cursor.
604 * @n: another &struct list_head to use as temporary storage
605 * @head: the head for your list.
607 #define list_for_each_prev_safe(pos, n, head) \
608 for (pos = (head)->prev, n = pos->prev; \
610 pos = n, n = pos->prev)
613 * list_entry_is_head - test if the entry points to the head of the list
614 * @pos: the type * to cursor
615 * @head: the head for your list.
616 * @member: the name of the list_head within the struct.
618 #define list_entry_is_head(pos, head, member) \
619 (&pos->member == (head))
622 * list_for_each_entry - iterate over list of given type
623 * @pos: the type * to use as a loop cursor.
624 * @head: the head for your list.
625 * @member: the name of the list_head within the struct.
627 #define list_for_each_entry(pos, head, member) \
628 for (pos = list_first_entry(head, typeof(*pos), member); \
629 !list_entry_is_head(pos, head, member); \
630 pos = list_next_entry(pos, member))
633 * list_for_each_entry_reverse - iterate backwards over list of given type.
634 * @pos: the type * to use as a loop cursor.
635 * @head: the head for your list.
636 * @member: the name of the list_head within the struct.
638 #define list_for_each_entry_reverse(pos, head, member) \
639 for (pos = list_last_entry(head, typeof(*pos), member); \
640 !list_entry_is_head(pos, head, member); \
641 pos = list_prev_entry(pos, member))
644 * list_prepare_entry - prepare a pos entry for use in list_for_each_entry_continue()
645 * @pos: the type * to use as a start point
646 * @head: the head of the list
647 * @member: the name of the list_head within the struct.
649 * Prepares a pos entry for use as a start point in list_for_each_entry_continue().
651 #define list_prepare_entry(pos, head, member) \
652 ((pos) ? : list_entry(head, typeof(*pos), member))
655 * list_for_each_entry_continue - continue iteration over list of given type
656 * @pos: the type * to use as a loop cursor.
657 * @head: the head for your list.
658 * @member: the name of the list_head within the struct.
660 * Continue to iterate over list of given type, continuing after
661 * the current position.
663 #define list_for_each_entry_continue(pos, head, member) \
664 for (pos = list_next_entry(pos, member); \
665 !list_entry_is_head(pos, head, member); \
666 pos = list_next_entry(pos, member))
669 * list_for_each_entry_continue_reverse - iterate backwards from the given point
670 * @pos: the type * to use as a loop cursor.
671 * @head: the head for your list.
672 * @member: the name of the list_head within the struct.
674 * Start to iterate over list of given type backwards, continuing after
675 * the current position.
677 #define list_for_each_entry_continue_reverse(pos, head, member) \
678 for (pos = list_prev_entry(pos, member); \
679 !list_entry_is_head(pos, head, member); \
680 pos = list_prev_entry(pos, member))
683 * list_for_each_entry_from - iterate over list of given type from the current point
684 * @pos: the type * to use as a loop cursor.
685 * @head: the head for your list.
686 * @member: the name of the list_head within the struct.
688 * Iterate over list of given type, continuing from current position.
690 #define list_for_each_entry_from(pos, head, member) \
691 for (; !list_entry_is_head(pos, head, member); \
692 pos = list_next_entry(pos, member))
695 * list_for_each_entry_from_reverse - iterate backwards over list of given type
696 * from the current point
697 * @pos: the type * to use as a loop cursor.
698 * @head: the head for your list.
699 * @member: the name of the list_head within the struct.
701 * Iterate backwards over list of given type, continuing from current position.
703 #define list_for_each_entry_from_reverse(pos, head, member) \
704 for (; !list_entry_is_head(pos, head, member); \
705 pos = list_prev_entry(pos, member))
708 * list_for_each_entry_safe - iterate over list of given type safe against removal of list entry
709 * @pos: the type * to use as a loop cursor.
710 * @n: another type * to use as temporary storage
711 * @head: the head for your list.
712 * @member: the name of the list_head within the struct.
714 #define list_for_each_entry_safe(pos, n, head, member) \
715 for (pos = list_first_entry(head, typeof(*pos), member), \
716 n = list_next_entry(pos, member); \
717 !list_entry_is_head(pos, head, member); \
718 pos = n, n = list_next_entry(n, member))
721 * list_for_each_entry_safe_continue - continue list iteration safe against removal
722 * @pos: the type * to use as a loop cursor.
723 * @n: another type * to use as temporary storage
724 * @head: the head for your list.
725 * @member: the name of the list_head within the struct.
727 * Iterate over list of given type, continuing after current point,
728 * safe against removal of list entry.
730 #define list_for_each_entry_safe_continue(pos, n, head, member) \
731 for (pos = list_next_entry(pos, member), \
732 n = list_next_entry(pos, member); \
733 !list_entry_is_head(pos, head, member); \
734 pos = n, n = list_next_entry(n, member))
737 * list_for_each_entry_safe_from - iterate over list from current point safe against removal
738 * @pos: the type * to use as a loop cursor.
739 * @n: another type * to use as temporary storage
740 * @head: the head for your list.
741 * @member: the name of the list_head within the struct.
743 * Iterate over list of given type from current point, safe against
744 * removal of list entry.
746 #define list_for_each_entry_safe_from(pos, n, head, member) \
747 for (n = list_next_entry(pos, member); \
748 !list_entry_is_head(pos, head, member); \
749 pos = n, n = list_next_entry(n, member))
752 * list_for_each_entry_safe_reverse - iterate backwards over list safe against removal
753 * @pos: the type * to use as a loop cursor.
754 * @n: another type * to use as temporary storage
755 * @head: the head for your list.
756 * @member: the name of the list_head within the struct.
758 * Iterate backwards over list of given type, safe against removal
761 #define list_for_each_entry_safe_reverse(pos, n, head, member) \
762 for (pos = list_last_entry(head, typeof(*pos), member), \
763 n = list_prev_entry(pos, member); \
764 !list_entry_is_head(pos, head, member); \
765 pos = n, n = list_prev_entry(n, member))
768 * list_safe_reset_next - reset a stale list_for_each_entry_safe loop
769 * @pos: the loop cursor used in the list_for_each_entry_safe loop
770 * @n: temporary storage used in list_for_each_entry_safe
771 * @member: the name of the list_head within the struct.
773 * list_safe_reset_next is not safe to use in general if the list may be
774 * modified concurrently (eg. the lock is dropped in the loop body). An
775 * exception to this is if the cursor element (pos) is pinned in the list,
776 * and list_safe_reset_next is called after re-taking the lock and before
777 * completing the current iteration of the loop body.
779 #define list_safe_reset_next(pos, n, member) \
780 n = list_next_entry(pos, member)
783 * Double linked lists with a single pointer list head.
784 * Mostly useful for hash tables where the two pointer list head is
786 * You lose the ability to access the tail in O(1).
789 #define HLIST_HEAD_INIT { .first = NULL }
790 #define HLIST_HEAD(name) struct hlist_head name = { .first = NULL }
791 #define INIT_HLIST_HEAD(ptr) ((ptr)->first = NULL)
792 static inline void INIT_HLIST_NODE(struct hlist_node
*h
)
799 * hlist_unhashed - Has node been removed from list and reinitialized?
800 * @h: Node to be checked
802 * Not that not all removal functions will leave a node in unhashed
803 * state. For example, hlist_nulls_del_init_rcu() does leave the
804 * node in unhashed state, but hlist_nulls_del() does not.
806 static inline int hlist_unhashed(const struct hlist_node
*h
)
812 * hlist_unhashed_lockless - Version of hlist_unhashed for lockless use
813 * @h: Node to be checked
815 * This variant of hlist_unhashed() must be used in lockless contexts
816 * to avoid potential load-tearing. The READ_ONCE() is paired with the
817 * various WRITE_ONCE() in hlist helpers that are defined below.
819 static inline int hlist_unhashed_lockless(const struct hlist_node
*h
)
821 return !READ_ONCE(h
->pprev
);
825 * hlist_empty - Is the specified hlist_head structure an empty hlist?
826 * @h: Structure to check.
828 static inline int hlist_empty(const struct hlist_head
*h
)
830 return !READ_ONCE(h
->first
);
833 static inline void __hlist_del(struct hlist_node
*n
)
835 struct hlist_node
*next
= n
->next
;
836 struct hlist_node
**pprev
= n
->pprev
;
838 WRITE_ONCE(*pprev
, next
);
840 WRITE_ONCE(next
->pprev
, pprev
);
844 * hlist_del - Delete the specified hlist_node from its list
845 * @n: Node to delete.
847 * Note that this function leaves the node in hashed state. Use
848 * hlist_del_init() or similar instead to unhash @n.
850 static inline void hlist_del(struct hlist_node
*n
)
853 n
->next
= LIST_POISON1
;
854 n
->pprev
= LIST_POISON2
;
858 * hlist_del_init - Delete the specified hlist_node from its list and initialize
859 * @n: Node to delete.
861 * Note that this function leaves the node in unhashed state.
863 static inline void hlist_del_init(struct hlist_node
*n
)
865 if (!hlist_unhashed(n
)) {
872 * hlist_add_head - add a new entry at the beginning of the hlist
873 * @n: new entry to be added
874 * @h: hlist head to add it after
876 * Insert a new entry after the specified head.
877 * This is good for implementing stacks.
879 static inline void hlist_add_head(struct hlist_node
*n
, struct hlist_head
*h
)
881 struct hlist_node
*first
= h
->first
;
882 WRITE_ONCE(n
->next
, first
);
884 WRITE_ONCE(first
->pprev
, &n
->next
);
885 WRITE_ONCE(h
->first
, n
);
886 WRITE_ONCE(n
->pprev
, &h
->first
);
890 * hlist_add_before - add a new entry before the one specified
891 * @n: new entry to be added
892 * @next: hlist node to add it before, which must be non-NULL
894 static inline void hlist_add_before(struct hlist_node
*n
,
895 struct hlist_node
*next
)
897 WRITE_ONCE(n
->pprev
, next
->pprev
);
898 WRITE_ONCE(n
->next
, next
);
899 WRITE_ONCE(next
->pprev
, &n
->next
);
900 WRITE_ONCE(*(n
->pprev
), n
);
904 * hlist_add_behind - add a new entry after the one specified
905 * @n: new entry to be added
906 * @prev: hlist node to add it after, which must be non-NULL
908 static inline void hlist_add_behind(struct hlist_node
*n
,
909 struct hlist_node
*prev
)
911 WRITE_ONCE(n
->next
, prev
->next
);
912 WRITE_ONCE(prev
->next
, n
);
913 WRITE_ONCE(n
->pprev
, &prev
->next
);
916 WRITE_ONCE(n
->next
->pprev
, &n
->next
);
920 * hlist_add_fake - create a fake hlist consisting of a single headless node
921 * @n: Node to make a fake list out of
923 * This makes @n appear to be its own predecessor on a headless hlist.
924 * The point of this is to allow things like hlist_del() to work correctly
925 * in cases where there is no list.
927 static inline void hlist_add_fake(struct hlist_node
*n
)
933 * hlist_fake: Is this node a fake hlist?
934 * @h: Node to check for being a self-referential fake hlist.
936 static inline bool hlist_fake(struct hlist_node
*h
)
938 return h
->pprev
== &h
->next
;
942 * hlist_is_singular_node - is node the only element of the specified hlist?
943 * @n: Node to check for singularity.
944 * @h: Header for potentially singular list.
946 * Check whether the node is the only node of the head without
947 * accessing head, thus avoiding unnecessary cache misses.
950 hlist_is_singular_node(struct hlist_node
*n
, struct hlist_head
*h
)
952 return !n
->next
&& n
->pprev
== &h
->first
;
956 * hlist_move_list - Move an hlist
957 * @old: hlist_head for old list.
958 * @new: hlist_head for new list.
960 * Move a list from one list head to another. Fixup the pprev
961 * reference of the first entry if it exists.
963 static inline void hlist_move_list(struct hlist_head
*old
,
964 struct hlist_head
*new)
966 new->first
= old
->first
;
968 new->first
->pprev
= &new->first
;
972 #define hlist_entry(ptr, type, member) container_of(ptr,type,member)
974 #define hlist_for_each(pos, head) \
975 for (pos = (head)->first; pos ; pos = pos->next)
977 #define hlist_for_each_safe(pos, n, head) \
978 for (pos = (head)->first; pos && ({ n = pos->next; 1; }); \
981 #define hlist_entry_safe(ptr, type, member) \
982 ({ typeof(ptr) ____ptr = (ptr); \
983 ____ptr ? hlist_entry(____ptr, type, member) : NULL; \
987 * hlist_for_each_entry - iterate over list of given type
988 * @pos: the type * to use as a loop cursor.
989 * @head: the head for your list.
990 * @member: the name of the hlist_node within the struct.
992 #define hlist_for_each_entry(pos, head, member) \
993 for (pos = hlist_entry_safe((head)->first, typeof(*(pos)), member);\
995 pos = hlist_entry_safe((pos)->member.next, typeof(*(pos)), member))
998 * hlist_for_each_entry_continue - iterate over a hlist continuing after current point
999 * @pos: the type * to use as a loop cursor.
1000 * @member: the name of the hlist_node within the struct.
1002 #define hlist_for_each_entry_continue(pos, member) \
1003 for (pos = hlist_entry_safe((pos)->member.next, typeof(*(pos)), member);\
1005 pos = hlist_entry_safe((pos)->member.next, typeof(*(pos)), member))
1008 * hlist_for_each_entry_from - iterate over a hlist continuing from current point
1009 * @pos: the type * to use as a loop cursor.
1010 * @member: the name of the hlist_node within the struct.
1012 #define hlist_for_each_entry_from(pos, member) \
1014 pos = hlist_entry_safe((pos)->member.next, typeof(*(pos)), member))
1017 * hlist_for_each_entry_safe - iterate over list of given type safe against removal of list entry
1018 * @pos: the type * to use as a loop cursor.
1019 * @n: a &struct hlist_node to use as temporary storage
1020 * @head: the head for your list.
1021 * @member: the name of the hlist_node within the struct.
1023 #define hlist_for_each_entry_safe(pos, n, head, member) \
1024 for (pos = hlist_entry_safe((head)->first, typeof(*pos), member);\
1025 pos && ({ n = pos->member.next; 1; }); \
1026 pos = hlist_entry_safe(n, typeof(*pos), member))