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 * Simple 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_for_each_entry - iterate over list of given type
614 * @pos: the type * to use as a loop cursor.
615 * @head: the head for your list.
616 * @member: the name of the list_head within the struct.
618 #define list_for_each_entry(pos, head, member) \
619 for (pos = list_first_entry(head, typeof(*pos), member); \
620 &pos->member != (head); \
621 pos = list_next_entry(pos, member))
624 * list_for_each_entry_reverse - iterate backwards over list of given type.
625 * @pos: the type * to use as a loop cursor.
626 * @head: the head for your list.
627 * @member: the name of the list_head within the struct.
629 #define list_for_each_entry_reverse(pos, head, member) \
630 for (pos = list_last_entry(head, typeof(*pos), member); \
631 &pos->member != (head); \
632 pos = list_prev_entry(pos, member))
635 * list_prepare_entry - prepare a pos entry for use in list_for_each_entry_continue()
636 * @pos: the type * to use as a start point
637 * @head: the head of the list
638 * @member: the name of the list_head within the struct.
640 * Prepares a pos entry for use as a start point in list_for_each_entry_continue().
642 #define list_prepare_entry(pos, head, member) \
643 ((pos) ? : list_entry(head, typeof(*pos), member))
646 * list_for_each_entry_continue - continue iteration over list of given type
647 * @pos: the type * to use as a loop cursor.
648 * @head: the head for your list.
649 * @member: the name of the list_head within the struct.
651 * Continue to iterate over list of given type, continuing after
652 * the current position.
654 #define list_for_each_entry_continue(pos, head, member) \
655 for (pos = list_next_entry(pos, member); \
656 &pos->member != (head); \
657 pos = list_next_entry(pos, member))
660 * list_for_each_entry_continue_reverse - iterate backwards from the given point
661 * @pos: the type * to use as a loop cursor.
662 * @head: the head for your list.
663 * @member: the name of the list_head within the struct.
665 * Start to iterate over list of given type backwards, continuing after
666 * the current position.
668 #define list_for_each_entry_continue_reverse(pos, head, member) \
669 for (pos = list_prev_entry(pos, member); \
670 &pos->member != (head); \
671 pos = list_prev_entry(pos, member))
674 * list_for_each_entry_from - iterate over list of given type from the current point
675 * @pos: the type * to use as a loop cursor.
676 * @head: the head for your list.
677 * @member: the name of the list_head within the struct.
679 * Iterate over list of given type, continuing from current position.
681 #define list_for_each_entry_from(pos, head, member) \
682 for (; &pos->member != (head); \
683 pos = list_next_entry(pos, member))
686 * list_for_each_entry_from_reverse - iterate backwards over list of given type
687 * from the current point
688 * @pos: the type * to use as a loop cursor.
689 * @head: the head for your list.
690 * @member: the name of the list_head within the struct.
692 * Iterate backwards over list of given type, continuing from current position.
694 #define list_for_each_entry_from_reverse(pos, head, member) \
695 for (; &pos->member != (head); \
696 pos = list_prev_entry(pos, member))
699 * list_for_each_entry_safe - iterate over list of given type safe against removal of list entry
700 * @pos: the type * to use as a loop cursor.
701 * @n: another type * to use as temporary storage
702 * @head: the head for your list.
703 * @member: the name of the list_head within the struct.
705 #define list_for_each_entry_safe(pos, n, head, member) \
706 for (pos = list_first_entry(head, typeof(*pos), member), \
707 n = list_next_entry(pos, member); \
708 &pos->member != (head); \
709 pos = n, n = list_next_entry(n, member))
712 * list_for_each_entry_safe_continue - continue list iteration safe against removal
713 * @pos: the type * to use as a loop cursor.
714 * @n: another type * to use as temporary storage
715 * @head: the head for your list.
716 * @member: the name of the list_head within the struct.
718 * Iterate over list of given type, continuing after current point,
719 * safe against removal of list entry.
721 #define list_for_each_entry_safe_continue(pos, n, head, member) \
722 for (pos = list_next_entry(pos, member), \
723 n = list_next_entry(pos, member); \
724 &pos->member != (head); \
725 pos = n, n = list_next_entry(n, member))
728 * list_for_each_entry_safe_from - iterate over list from current point safe against removal
729 * @pos: the type * to use as a loop cursor.
730 * @n: another type * to use as temporary storage
731 * @head: the head for your list.
732 * @member: the name of the list_head within the struct.
734 * Iterate over list of given type from current point, safe against
735 * removal of list entry.
737 #define list_for_each_entry_safe_from(pos, n, head, member) \
738 for (n = list_next_entry(pos, member); \
739 &pos->member != (head); \
740 pos = n, n = list_next_entry(n, member))
743 * list_for_each_entry_safe_reverse - iterate backwards over list safe against removal
744 * @pos: the type * to use as a loop cursor.
745 * @n: another type * to use as temporary storage
746 * @head: the head for your list.
747 * @member: the name of the list_head within the struct.
749 * Iterate backwards over list of given type, safe against removal
752 #define list_for_each_entry_safe_reverse(pos, n, head, member) \
753 for (pos = list_last_entry(head, typeof(*pos), member), \
754 n = list_prev_entry(pos, member); \
755 &pos->member != (head); \
756 pos = n, n = list_prev_entry(n, member))
759 * list_safe_reset_next - reset a stale list_for_each_entry_safe loop
760 * @pos: the loop cursor used in the list_for_each_entry_safe loop
761 * @n: temporary storage used in list_for_each_entry_safe
762 * @member: the name of the list_head within the struct.
764 * list_safe_reset_next is not safe to use in general if the list may be
765 * modified concurrently (eg. the lock is dropped in the loop body). An
766 * exception to this is if the cursor element (pos) is pinned in the list,
767 * and list_safe_reset_next is called after re-taking the lock and before
768 * completing the current iteration of the loop body.
770 #define list_safe_reset_next(pos, n, member) \
771 n = list_next_entry(pos, member)
774 * Double linked lists with a single pointer list head.
775 * Mostly useful for hash tables where the two pointer list head is
777 * You lose the ability to access the tail in O(1).
780 #define HLIST_HEAD_INIT { .first = NULL }
781 #define HLIST_HEAD(name) struct hlist_head name = { .first = NULL }
782 #define INIT_HLIST_HEAD(ptr) ((ptr)->first = NULL)
783 static inline void INIT_HLIST_NODE(struct hlist_node *h)
790 * hlist_unhashed - Has node been removed from list and reinitialized?
791 * @h: Node to be checked
793 * Not that not all removal functions will leave a node in unhashed
794 * state. For example, hlist_nulls_del_init_rcu() does leave the
795 * node in unhashed state, but hlist_nulls_del() does not.
797 static inline int hlist_unhashed(const struct hlist_node *h)
803 * hlist_unhashed_lockless - Version of hlist_unhashed for lockless use
804 * @h: Node to be checked
806 * This variant of hlist_unhashed() must be used in lockless contexts
807 * to avoid potential load-tearing. The READ_ONCE() is paired with the
808 * various WRITE_ONCE() in hlist helpers that are defined below.
810 static inline int hlist_unhashed_lockless(const struct hlist_node *h)
812 return !READ_ONCE(h->pprev);
816 * hlist_empty - Is the specified hlist_head structure an empty hlist?
817 * @h: Structure to check.
819 static inline int hlist_empty(const struct hlist_head *h)
821 return !READ_ONCE(h->first);
824 static inline void __hlist_del(struct hlist_node *n)
826 struct hlist_node *next = n->next;
827 struct hlist_node **pprev = n->pprev;
829 WRITE_ONCE(*pprev, next);
831 WRITE_ONCE(next->pprev, pprev);
835 * hlist_del - Delete the specified hlist_node from its list
836 * @n: Node to delete.
838 * Note that this function leaves the node in hashed state. Use
839 * hlist_del_init() or similar instead to unhash @n.
841 static inline void hlist_del(struct hlist_node *n)
844 n->next = LIST_POISON1;
845 n->pprev = LIST_POISON2;
849 * hlist_del_init - Delete the specified hlist_node from its list and initialize
850 * @n: Node to delete.
852 * Note that this function leaves the node in unhashed state.
854 static inline void hlist_del_init(struct hlist_node *n)
856 if (!hlist_unhashed(n)) {
863 * hlist_add_head - add a new entry at the beginning of the hlist
864 * @n: new entry to be added
865 * @h: hlist head to add it after
867 * Insert a new entry after the specified head.
868 * This is good for implementing stacks.
870 static inline void hlist_add_head(struct hlist_node *n, struct hlist_head *h)
872 struct hlist_node *first = h->first;
873 WRITE_ONCE(n->next, first);
875 WRITE_ONCE(first->pprev, &n->next);
876 WRITE_ONCE(h->first, n);
877 WRITE_ONCE(n->pprev, &h->first);
881 * hlist_add_before - add a new entry before the one specified
882 * @n: new entry to be added
883 * @next: hlist node to add it before, which must be non-NULL
885 static inline void hlist_add_before(struct hlist_node *n,
886 struct hlist_node *next)
888 WRITE_ONCE(n->pprev, next->pprev);
889 WRITE_ONCE(n->next, next);
890 WRITE_ONCE(next->pprev, &n->next);
891 WRITE_ONCE(*(n->pprev), n);
895 * hlist_add_behing - add a new entry after the one specified
896 * @n: new entry to be added
897 * @prev: hlist node to add it after, which must be non-NULL
899 static inline void hlist_add_behind(struct hlist_node *n,
900 struct hlist_node *prev)
902 WRITE_ONCE(n->next, prev->next);
903 WRITE_ONCE(prev->next, n);
904 WRITE_ONCE(n->pprev, &prev->next);
907 WRITE_ONCE(n->next->pprev, &n->next);
911 * hlist_add_fake - create a fake hlist consisting of a single headless node
912 * @n: Node to make a fake list out of
914 * This makes @n appear to be its own predecessor on a headless hlist.
915 * The point of this is to allow things like hlist_del() to work correctly
916 * in cases where there is no list.
918 static inline void hlist_add_fake(struct hlist_node *n)
924 * hlist_fake: Is this node a fake hlist?
925 * @h: Node to check for being a self-referential fake hlist.
927 static inline bool hlist_fake(struct hlist_node *h)
929 return h->pprev == &h->next;
933 * hlist_is_singular_node - is node the only element of the specified hlist?
934 * @n: Node to check for singularity.
935 * @h: Header for potentially singular list.
937 * Check whether the node is the only node of the head without
938 * accessing head, thus avoiding unnecessary cache misses.
941 hlist_is_singular_node(struct hlist_node *n, struct hlist_head *h)
943 return !n->next && n->pprev == &h->first;
947 * hlist_move_list - Move an hlist
948 * @old: hlist_head for old list.
949 * @new: hlist_head for new list.
951 * Move a list from one list head to another. Fixup the pprev
952 * reference of the first entry if it exists.
954 static inline void hlist_move_list(struct hlist_head *old,
955 struct hlist_head *new)
957 new->first = old->first;
959 new->first->pprev = &new->first;
963 #define hlist_entry(ptr, type, member) container_of(ptr,type,member)
965 #define hlist_for_each(pos, head) \
966 for (pos = (head)->first; pos ; pos = pos->next)
968 #define hlist_for_each_safe(pos, n, head) \
969 for (pos = (head)->first; pos && ({ n = pos->next; 1; }); \
972 #define hlist_entry_safe(ptr, type, member) \
973 ({ typeof(ptr) ____ptr = (ptr); \
974 ____ptr ? hlist_entry(____ptr, type, member) : NULL; \
978 * hlist_for_each_entry - iterate over list of given type
979 * @pos: the type * to use as a loop cursor.
980 * @head: the head for your list.
981 * @member: the name of the hlist_node within the struct.
983 #define hlist_for_each_entry(pos, head, member) \
984 for (pos = hlist_entry_safe((head)->first, typeof(*(pos)), member);\
986 pos = hlist_entry_safe((pos)->member.next, typeof(*(pos)), member))
989 * hlist_for_each_entry_continue - iterate over a hlist continuing after current point
990 * @pos: the type * to use as a loop cursor.
991 * @member: the name of the hlist_node within the struct.
993 #define hlist_for_each_entry_continue(pos, member) \
994 for (pos = hlist_entry_safe((pos)->member.next, typeof(*(pos)), member);\
996 pos = hlist_entry_safe((pos)->member.next, typeof(*(pos)), member))
999 * hlist_for_each_entry_from - iterate over a hlist continuing from current point
1000 * @pos: the type * to use as a loop cursor.
1001 * @member: the name of the hlist_node within the struct.
1003 #define hlist_for_each_entry_from(pos, member) \
1005 pos = hlist_entry_safe((pos)->member.next, typeof(*(pos)), member))
1008 * hlist_for_each_entry_safe - iterate over list of given type safe against removal of list entry
1009 * @pos: the type * to use as a loop cursor.
1010 * @n: a &struct hlist_node to use as temporary storage
1011 * @head: the head for your list.
1012 * @member: the name of the hlist_node within the struct.
1014 #define hlist_for_each_entry_safe(pos, n, head, member) \
1015 for (pos = hlist_entry_safe((head)->first, typeof(*pos), member);\
1016 pos && ({ n = pos->member.next; 1; }); \
1017 pos = hlist_entry_safe(n, typeof(*pos), member))