1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef _LINUX_LIST_H
3 #define _LINUX_LIST_H
4
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>
10
11 /*
12 * Simple doubly linked list implementation.
13 *
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.
19 */
20
21 #define LIST_HEAD_INIT(name) { &(name), &(name) }
22
23 #define LIST_HEAD(name) \
24 struct list_head name = LIST_HEAD_INIT(name)
25
26 static inline void INIT_LIST_HEAD(struct list_head *list)
27 {
28 WRITE_ONCE(list->next, list);
29 list->prev = list;
30 }
31
32 #ifdef CONFIG_DEBUG_LIST
33 extern bool __list_add_valid(struct list_head *new,
34 struct list_head *prev,
35 struct list_head *next);
36 extern bool __list_del_entry_valid(struct list_head *entry);
37 #else
38 static inline bool __list_add_valid(struct list_head *new,
39 struct list_head *prev,
40 struct list_head *next)
41 {
42 return true;
43 }
44 static inline bool __list_del_entry_valid(struct list_head *entry)
45 {
46 return true;
47 }
48 #endif
49
50 /*
51 * Insert a new entry between two known consecutive entries.
52 *
53 * This is only for internal list manipulation where we know
54 * the prev/next entries already!
55 */
56 static inline void __list_add(struct list_head *new,
57 struct list_head *prev,
58 struct list_head *next)
59 {
60 if (!__list_add_valid(new, prev, next))
61 return;
62
63 next->prev = new;
64 new->next = next;
65 new->prev = prev;
66 WRITE_ONCE(prev->next, new);
67 }
68
69 /**
70 * list_add - add a new entry
71 * @new: new entry to be added
72 * @head: list head to add it after
73 *
74 * Insert a new entry after the specified head.
75 * This is good for implementing stacks.
76 */
77 static inline void list_add(struct list_head *new, struct list_head *head)
78 {
79 __list_add(new, head, head->next);
80 }
81
82
83 /**
84 * list_add_tail - add a new entry
85 * @new: new entry to be added
86 * @head: list head to add it before
87 *
88 * Insert a new entry before the specified head.
89 * This is useful for implementing queues.
90 */
91 static inline void list_add_tail(struct list_head *new, struct list_head *head)
92 {
93 __list_add(new, head->prev, head);
94 }
95
96 /*
97 * Delete a list entry by making the prev/next entries
98 * point to each other.
99 *
100 * This is only for internal list manipulation where we know
101 * the prev/next entries already!
102 */
103 static inline void __list_del(struct list_head * prev, struct list_head * next)
104 {
105 next->prev = prev;
106 WRITE_ONCE(prev->next, next);
107 }
108
109 /*
110 * Delete a list entry and clear the 'prev' pointer.
111 *
112 * This is a special-purpose list clearing method used in the networking code
113 * for lists allocated as per-cpu, where we don't want to incur the extra
114 * WRITE_ONCE() overhead of a regular list_del_init(). The code that uses this
115 * needs to check the node 'prev' pointer instead of calling list_empty().
116 */
117 static inline void __list_del_clearprev(struct list_head *entry)
118 {
119 __list_del(entry->prev, entry->next);
120 entry->prev = NULL;
121 }
122
123 /**
124 * list_del - deletes entry from list.
125 * @entry: the element to delete from the list.
126 * Note: list_empty() on entry does not return true after this, the entry is
127 * in an undefined state.
128 */
129 static inline void __list_del_entry(struct list_head *entry)
130 {
131 if (!__list_del_entry_valid(entry))
132 return;
133
134 __list_del(entry->prev, entry->next);
135 }
136
137 static inline void list_del(struct list_head *entry)
138 {
139 __list_del_entry(entry);
140 entry->next = LIST_POISON1;
141 entry->prev = LIST_POISON2;
142 }
143
144 /**
145 * list_replace - replace old entry by new one
146 * @old : the element to be replaced
147 * @new : the new element to insert
148 *
149 * If @old was empty, it will be overwritten.
150 */
151 static inline void list_replace(struct list_head *old,
152 struct list_head *new)
153 {
154 new->next = old->next;
155 new->next->prev = new;
156 new->prev = old->prev;
157 new->prev->next = new;
158 }
159
160 static inline void list_replace_init(struct list_head *old,
161 struct list_head *new)
162 {
163 list_replace(old, new);
164 INIT_LIST_HEAD(old);
165 }
166
167 /**
168 * list_swap - replace entry1 with entry2 and re-add entry1 at entry2's position
169 * @entry1: the location to place entry2
170 * @entry2: the location to place entry1
171 */
172 static inline void list_swap(struct list_head *entry1,
173 struct list_head *entry2)
174 {
175 struct list_head *pos = entry2->prev;
176
177 list_del(entry2);
178 list_replace(entry1, entry2);
179 if (pos == entry1)
180 pos = entry2;
181 list_add(entry1, pos);
182 }
183
184 /**
185 * list_del_init - deletes entry from list and reinitialize it.
186 * @entry: the element to delete from the list.
187 */
188 static inline void list_del_init(struct list_head *entry)
189 {
190 __list_del_entry(entry);
191 INIT_LIST_HEAD(entry);
192 }
193
194 /**
195 * list_move - delete from one list and add as another's head
196 * @list: the entry to move
197 * @head: the head that will precede our entry
198 */
199 static inline void list_move(struct list_head *list, struct list_head *head)
200 {
201 __list_del_entry(list);
202 list_add(list, head);
203 }
204
205 /**
206 * list_move_tail - delete from one list and add as another's tail
207 * @list: the entry to move
208 * @head: the head that will follow our entry
209 */
210 static inline void list_move_tail(struct list_head *list,
211 struct list_head *head)
212 {
213 __list_del_entry(list);
214 list_add_tail(list, head);
215 }
216
217 /**
218 * list_bulk_move_tail - move a subsection of a list to its tail
219 * @head: the head that will follow our entry
220 * @first: first entry to move
221 * @last: last entry to move, can be the same as first
222 *
223 * Move all entries between @first and including @last before @head.
224 * All three entries must belong to the same linked list.
225 */
226 static inline void list_bulk_move_tail(struct list_head *head,
227 struct list_head *first,
228 struct list_head *last)
229 {
230 first->prev->next = last->next;
231 last->next->prev = first->prev;
232
233 head->prev->next = first;
234 first->prev = head->prev;
235
236 last->next = head;
237 head->prev = last;
238 }
239
240 /**
241 * list_is_first -- tests whether @list is the first entry in list @head
242 * @list: the entry to test
243 * @head: the head of the list
244 */
245 static inline int list_is_first(const struct list_head *list,
246 const struct list_head *head)
247 {
248 return list->prev == head;
249 }
250
251 /**
252 * list_is_last - tests whether @list is the last entry in list @head
253 * @list: the entry to test
254 * @head: the head of the list
255 */
256 static inline int list_is_last(const struct list_head *list,
257 const struct list_head *head)
258 {
259 return list->next == head;
260 }
261
262 /**
263 * list_empty - tests whether a list is empty
264 * @head: the list to test.
265 */
266 static inline int list_empty(const struct list_head *head)
267 {
268 return READ_ONCE(head->next) == head;
269 }
270
271 /**
272 * list_empty_careful - tests whether a list is empty and not being modified
273 * @head: the list to test
274 *
275 * Description:
276 * tests whether a list is empty _and_ checks that no other CPU might be
277 * in the process of modifying either member (next or prev)
278 *
279 * NOTE: using list_empty_careful() without synchronization
280 * can only be safe if the only activity that can happen
281 * to the list entry is list_del_init(). Eg. it cannot be used
282 * if another CPU could re-list_add() it.
283 */
284 static inline int list_empty_careful(const struct list_head *head)
285 {
286 struct list_head *next = head->next;
287 return (next == head) && (next == head->prev);
288 }
289
290 /**
291 * list_rotate_left - rotate the list to the left
292 * @head: the head of the list
293 */
294 static inline void list_rotate_left(struct list_head *head)
295 {
296 struct list_head *first;
297
298 if (!list_empty(head)) {
299 first = head->next;
300 list_move_tail(first, head);
301 }
302 }
303
304 /**
305 * list_rotate_to_front() - Rotate list to specific item.
306 * @list: The desired new front of the list.
307 * @head: The head of the list.
308 *
309 * Rotates list so that @list becomes the new front of the list.
310 */
311 static inline void list_rotate_to_front(struct list_head *list,
312 struct list_head *head)
313 {
314 /*
315 * Deletes the list head from the list denoted by @head and
316 * places it as the tail of @list, this effectively rotates the
317 * list so that @list is at the front.
318 */
319 list_move_tail(head, list);
320 }
321
322 /**
323 * list_is_singular - tests whether a list has just one entry.
324 * @head: the list to test.
325 */
326 static inline int list_is_singular(const struct list_head *head)
327 {
328 return !list_empty(head) && (head->next == head->prev);
329 }
330
331 static inline void __list_cut_position(struct list_head *list,
332 struct list_head *head, struct list_head *entry)
333 {
334 struct list_head *new_first = entry->next;
335 list->next = head->next;
336 list->next->prev = list;
337 list->prev = entry;
338 entry->next = list;
339 head->next = new_first;
340 new_first->prev = head;
341 }
342
343 /**
344 * list_cut_position - cut a list into two
345 * @list: a new list to add all removed entries
346 * @head: a list with entries
347 * @entry: an entry within head, could be the head itself
348 * and if so we won't cut the list
349 *
350 * This helper moves the initial part of @head, up to and
351 * including @entry, from @head to @list. You should
352 * pass on @entry an element you know is on @head. @list
353 * should be an empty list or a list you do not care about
354 * losing its data.
355 *
356 */
357 static inline void list_cut_position(struct list_head *list,
358 struct list_head *head, struct list_head *entry)
359 {
360 if (list_empty(head))
361 return;
362 if (list_is_singular(head) &&
363 (head->next != entry && head != entry))
364 return;
365 if (entry == head)
366 INIT_LIST_HEAD(list);
367 else
368 __list_cut_position(list, head, entry);
369 }
370
371 /**
372 * list_cut_before - cut a list into two, before given entry
373 * @list: a new list to add all removed entries
374 * @head: a list with entries
375 * @entry: an entry within head, could be the head itself
376 *
377 * This helper moves the initial part of @head, up to but
378 * excluding @entry, from @head to @list. You should pass
379 * in @entry an element you know is on @head. @list should
380 * be an empty list or a list you do not care about losing
381 * its data.
382 * If @entry == @head, all entries on @head are moved to
383 * @list.
384 */
385 static inline void list_cut_before(struct list_head *list,
386 struct list_head *head,
387 struct list_head *entry)
388 {
389 if (head->next == entry) {
390 INIT_LIST_HEAD(list);
391 return;
392 }
393 list->next = head->next;
394 list->next->prev = list;
395 list->prev = entry->prev;
396 list->prev->next = list;
397 head->next = entry;
398 entry->prev = head;
399 }
400
401 static inline void __list_splice(const struct list_head *list,
402 struct list_head *prev,
403 struct list_head *next)
404 {
405 struct list_head *first = list->next;
406 struct list_head *last = list->prev;
407
408 first->prev = prev;
409 prev->next = first;
410
411 last->next = next;
412 next->prev = last;
413 }
414
415 /**
416 * list_splice - join two lists, this is designed for stacks
417 * @list: the new list to add.
418 * @head: the place to add it in the first list.
419 */
420 static inline void list_splice(const struct list_head *list,
421 struct list_head *head)
422 {
423 if (!list_empty(list))
424 __list_splice(list, head, head->next);
425 }
426
427 /**
428 * list_splice_tail - join two lists, each list being a queue
429 * @list: the new list to add.
430 * @head: the place to add it in the first list.
431 */
432 static inline void list_splice_tail(struct list_head *list,
433 struct list_head *head)
434 {
435 if (!list_empty(list))
436 __list_splice(list, head->prev, head);
437 }
438
439 /**
440 * list_splice_init - join two lists and reinitialise the emptied list.
441 * @list: the new list to add.
442 * @head: the place to add it in the first list.
443 *
444 * The list at @list is reinitialised
445 */
446 static inline void list_splice_init(struct list_head *list,
447 struct list_head *head)
448 {
449 if (!list_empty(list)) {
450 __list_splice(list, head, head->next);
451 INIT_LIST_HEAD(list);
452 }
453 }
454
455 /**
456 * list_splice_tail_init - join two lists and reinitialise the emptied list
457 * @list: the new list to add.
458 * @head: the place to add it in the first list.
459 *
460 * Each of the lists is a queue.
461 * The list at @list is reinitialised
462 */
463 static inline void list_splice_tail_init(struct list_head *list,
464 struct list_head *head)
465 {
466 if (!list_empty(list)) {
467 __list_splice(list, head->prev, head);
468 INIT_LIST_HEAD(list);
469 }
470 }
471
472 /**
473 * list_entry - get the struct for this entry
474 * @ptr: the &struct list_head pointer.
475 * @type: the type of the struct this is embedded in.
476 * @member: the name of the list_head within the struct.
477 */
478 #define list_entry(ptr, type, member) \
479 container_of(ptr, type, member)
480
481 /**
482 * list_first_entry - get the first element from a list
483 * @ptr: the list head to take the element from.
484 * @type: the type of the struct this is embedded in.
485 * @member: the name of the list_head within the struct.
486 *
487 * Note, that list is expected to be not empty.
488 */
489 #define list_first_entry(ptr, type, member) \
490 list_entry((ptr)->next, type, member)
491
492 /**
493 * list_last_entry - get the last element from a list
494 * @ptr: the list head to take the element from.
495 * @type: the type of the struct this is embedded in.
496 * @member: the name of the list_head within the struct.
497 *
498 * Note, that list is expected to be not empty.
499 */
500 #define list_last_entry(ptr, type, member) \
501 list_entry((ptr)->prev, type, member)
502
503 /**
504 * list_first_entry_or_null - get the first element from a list
505 * @ptr: the list head to take the element from.
506 * @type: the type of the struct this is embedded in.
507 * @member: the name of the list_head within the struct.
508 *
509 * Note that if the list is empty, it returns NULL.
510 */
511 #define list_first_entry_or_null(ptr, type, member) ({ \
512 struct list_head *head__ = (ptr); \
513 struct list_head *pos__ = READ_ONCE(head__->next); \
514 pos__ != head__ ? list_entry(pos__, type, member) : NULL; \
515 })
516
517 /**
518 * list_next_entry - get the next element in list
519 * @pos: the type * to cursor
520 * @member: the name of the list_head within the struct.
521 */
522 #define list_next_entry(pos, member) \
523 list_entry((pos)->member.next, typeof(*(pos)), member)
524
525 /**
526 * list_prev_entry - get the prev element in list
527 * @pos: the type * to cursor
528 * @member: the name of the list_head within the struct.
529 */
530 #define list_prev_entry(pos, member) \
531 list_entry((pos)->member.prev, typeof(*(pos)), member)
532
533 /**
534 * list_for_each - iterate over a list
535 * @pos: the &struct list_head to use as a loop cursor.
536 * @head: the head for your list.
537 */
538 #define list_for_each(pos, head) \
539 for (pos = (head)->next; pos != (head); pos = pos->next)
540
541 /**
542 * list_for_each_prev - iterate over a list backwards
543 * @pos: the &struct list_head to use as a loop cursor.
544 * @head: the head for your list.
545 */
546 #define list_for_each_prev(pos, head) \
547 for (pos = (head)->prev; pos != (head); pos = pos->prev)
548
549 /**
550 * list_for_each_safe - iterate over a list safe against removal of list entry
551 * @pos: the &struct list_head to use as a loop cursor.
552 * @n: another &struct list_head to use as temporary storage
553 * @head: the head for your list.
554 */
555 #define list_for_each_safe(pos, n, head) \
556 for (pos = (head)->next, n = pos->next; pos != (head); \
557 pos = n, n = pos->next)
558
559 /**
560 * list_for_each_prev_safe - iterate over a list backwards safe against removal of list entry
561 * @pos: the &struct list_head to use as a loop cursor.
562 * @n: another &struct list_head to use as temporary storage
563 * @head: the head for your list.
564 */
565 #define list_for_each_prev_safe(pos, n, head) \
566 for (pos = (head)->prev, n = pos->prev; \
567 pos != (head); \
568 pos = n, n = pos->prev)
569
570 /**
571 * list_for_each_entry - iterate over list of given type
572 * @pos: the type * to use as a loop cursor.
573 * @head: the head for your list.
574 * @member: the name of the list_head within the struct.
575 */
576 #define list_for_each_entry(pos, head, member) \
577 for (pos = list_first_entry(head, typeof(*pos), member); \
578 &pos->member != (head); \
579 pos = list_next_entry(pos, member))
580
581 /**
582 * list_for_each_entry_reverse - iterate backwards over list of given type.
583 * @pos: the type * to use as a loop cursor.
584 * @head: the head for your list.
585 * @member: the name of the list_head within the struct.
586 */
587 #define list_for_each_entry_reverse(pos, head, member) \
588 for (pos = list_last_entry(head, typeof(*pos), member); \
589 &pos->member != (head); \
590 pos = list_prev_entry(pos, member))
591
592 /**
593 * list_prepare_entry - prepare a pos entry for use in list_for_each_entry_continue()
594 * @pos: the type * to use as a start point
595 * @head: the head of the list
596 * @member: the name of the list_head within the struct.
597 *
598 * Prepares a pos entry for use as a start point in list_for_each_entry_continue().
599 */
600 #define list_prepare_entry(pos, head, member) \
601 ((pos) ? : list_entry(head, typeof(*pos), member))
602
603 /**
604 * list_for_each_entry_continue - continue iteration over list of given type
605 * @pos: the type * to use as a loop cursor.
606 * @head: the head for your list.
607 * @member: the name of the list_head within the struct.
608 *
609 * Continue to iterate over list of given type, continuing after
610 * the current position.
611 */
612 #define list_for_each_entry_continue(pos, head, member) \
613 for (pos = list_next_entry(pos, member); \
614 &pos->member != (head); \
615 pos = list_next_entry(pos, member))
616
617 /**
618 * list_for_each_entry_continue_reverse - iterate backwards from the given point
619 * @pos: the type * to use as a loop cursor.
620 * @head: the head for your list.
621 * @member: the name of the list_head within the struct.
622 *
623 * Start to iterate over list of given type backwards, continuing after
624 * the current position.
625 */
626 #define list_for_each_entry_continue_reverse(pos, head, member) \
627 for (pos = list_prev_entry(pos, member); \
628 &pos->member != (head); \
629 pos = list_prev_entry(pos, member))
630
631 /**
632 * list_for_each_entry_from - iterate over list of given type from the current point
633 * @pos: the type * to use as a loop cursor.
634 * @head: the head for your list.
635 * @member: the name of the list_head within the struct.
636 *
637 * Iterate over list of given type, continuing from current position.
638 */
639 #define list_for_each_entry_from(pos, head, member) \
640 for (; &pos->member != (head); \
641 pos = list_next_entry(pos, member))
642
643 /**
644 * list_for_each_entry_from_reverse - iterate backwards over list of given type
645 * from the current point
646 * @pos: the type * to use as a loop cursor.
647 * @head: the head for your list.
648 * @member: the name of the list_head within the struct.
649 *
650 * Iterate backwards over list of given type, continuing from current position.
651 */
652 #define list_for_each_entry_from_reverse(pos, head, member) \
653 for (; &pos->member != (head); \
654 pos = list_prev_entry(pos, member))
655
656 /**
657 * list_for_each_entry_safe - iterate over list of given type safe against removal of list entry
658 * @pos: the type * to use as a loop cursor.
659 * @n: another type * to use as temporary storage
660 * @head: the head for your list.
661 * @member: the name of the list_head within the struct.
662 */
663 #define list_for_each_entry_safe(pos, n, head, member) \
664 for (pos = list_first_entry(head, typeof(*pos), member), \
665 n = list_next_entry(pos, member); \
666 &pos->member != (head); \
667 pos = n, n = list_next_entry(n, member))
668
669 /**
670 * list_for_each_entry_safe_continue - continue list iteration safe against removal
671 * @pos: the type * to use as a loop cursor.
672 * @n: another type * to use as temporary storage
673 * @head: the head for your list.
674 * @member: the name of the list_head within the struct.
675 *
676 * Iterate over list of given type, continuing after current point,
677 * safe against removal of list entry.
678 */
679 #define list_for_each_entry_safe_continue(pos, n, head, member) \
680 for (pos = list_next_entry(pos, member), \
681 n = list_next_entry(pos, member); \
682 &pos->member != (head); \
683 pos = n, n = list_next_entry(n, member))
684
685 /**
686 * list_for_each_entry_safe_from - iterate over list from current point safe against removal
687 * @pos: the type * to use as a loop cursor.
688 * @n: another type * to use as temporary storage
689 * @head: the head for your list.
690 * @member: the name of the list_head within the struct.
691 *
692 * Iterate over list of given type from current point, safe against
693 * removal of list entry.
694 */
695 #define list_for_each_entry_safe_from(pos, n, head, member) \
696 for (n = list_next_entry(pos, member); \
697 &pos->member != (head); \
698 pos = n, n = list_next_entry(n, member))
699
700 /**
701 * list_for_each_entry_safe_reverse - iterate backwards over list safe against removal
702 * @pos: the type * to use as a loop cursor.
703 * @n: another type * to use as temporary storage
704 * @head: the head for your list.
705 * @member: the name of the list_head within the struct.
706 *
707 * Iterate backwards over list of given type, safe against removal
708 * of list entry.
709 */
710 #define list_for_each_entry_safe_reverse(pos, n, head, member) \
711 for (pos = list_last_entry(head, typeof(*pos), member), \
712 n = list_prev_entry(pos, member); \
713 &pos->member != (head); \
714 pos = n, n = list_prev_entry(n, member))
715
716 /**
717 * list_safe_reset_next - reset a stale list_for_each_entry_safe loop
718 * @pos: the loop cursor used in the list_for_each_entry_safe loop
719 * @n: temporary storage used in list_for_each_entry_safe
720 * @member: the name of the list_head within the struct.
721 *
722 * list_safe_reset_next is not safe to use in general if the list may be
723 * modified concurrently (eg. the lock is dropped in the loop body). An
724 * exception to this is if the cursor element (pos) is pinned in the list,
725 * and list_safe_reset_next is called after re-taking the lock and before
726 * completing the current iteration of the loop body.
727 */
728 #define list_safe_reset_next(pos, n, member) \
729 n = list_next_entry(pos, member)
730
731 /*
732 * Double linked lists with a single pointer list head.
733 * Mostly useful for hash tables where the two pointer list head is
734 * too wasteful.
735 * You lose the ability to access the tail in O(1).
736 */
737
738 #define HLIST_HEAD_INIT { .first = NULL }
739 #define HLIST_HEAD(name) struct hlist_head name = { .first = NULL }
740 #define INIT_HLIST_HEAD(ptr) ((ptr)->first = NULL)
741 static inline void INIT_HLIST_NODE(struct hlist_node *h)
742 {
743 h->next = NULL;
744 h->pprev = NULL;
745 }
746
747 static inline int hlist_unhashed(const struct hlist_node *h)
748 {
749 return !h->pprev;
750 }
751
752 static inline int hlist_empty(const struct hlist_head *h)
753 {
754 return !READ_ONCE(h->first);
755 }
756
757 static inline void __hlist_del(struct hlist_node *n)
758 {
759 struct hlist_node *next = n->next;
760 struct hlist_node **pprev = n->pprev;
761
762 WRITE_ONCE(*pprev, next);
763 if (next)
764 next->pprev = pprev;
765 }
766
767 static inline void hlist_del(struct hlist_node *n)
768 {
769 __hlist_del(n);
770 n->next = LIST_POISON1;
771 n->pprev = LIST_POISON2;
772 }
773
774 static inline void hlist_del_init(struct hlist_node *n)
775 {
776 if (!hlist_unhashed(n)) {
777 __hlist_del(n);
778 INIT_HLIST_NODE(n);
779 }
780 }
781
782 static inline void hlist_add_head(struct hlist_node *n, struct hlist_head *h)
783 {
784 struct hlist_node *first = h->first;
785 n->next = first;
786 if (first)
787 first->pprev = &n->next;
788 WRITE_ONCE(h->first, n);
789 n->pprev = &h->first;
790 }
791
792 /* next must be != NULL */
793 static inline void hlist_add_before(struct hlist_node *n,
794 struct hlist_node *next)
795 {
796 n->pprev = next->pprev;
797 n->next = next;
798 next->pprev = &n->next;
799 WRITE_ONCE(*(n->pprev), n);
800 }
801
802 static inline void hlist_add_behind(struct hlist_node *n,
803 struct hlist_node *prev)
804 {
805 n->next = prev->next;
806 prev->next = n;
807 n->pprev = &prev->next;
808
809 if (n->next)
810 n->next->pprev = &n->next;
811 }
812
813 /* after that we'll appear to be on some hlist and hlist_del will work */
814 static inline void hlist_add_fake(struct hlist_node *n)
815 {
816 n->pprev = &n->next;
817 }
818
819 static inline bool hlist_fake(struct hlist_node *h)
820 {
821 return h->pprev == &h->next;
822 }
823
824 /*
825 * Check whether the node is the only node of the head without
826 * accessing head:
827 */
828 static inline bool
829 hlist_is_singular_node(struct hlist_node *n, struct hlist_head *h)
830 {
831 return !n->next && n->pprev == &h->first;
832 }
833
834 /*
835 * Move a list from one list head to another. Fixup the pprev
836 * reference of the first entry if it exists.
837 */
838 static inline void hlist_move_list(struct hlist_head *old,
839 struct hlist_head *new)
840 {
841 new->first = old->first;
842 if (new->first)
843 new->first->pprev = &new->first;
844 old->first = NULL;
845 }
846
847 #define hlist_entry(ptr, type, member) container_of(ptr,type,member)
848
849 #define hlist_for_each(pos, head) \
850 for (pos = (head)->first; pos ; pos = pos->next)
851
852 #define hlist_for_each_safe(pos, n, head) \
853 for (pos = (head)->first; pos && ({ n = pos->next; 1; }); \
854 pos = n)
855
856 #define hlist_entry_safe(ptr, type, member) \
857 ({ typeof(ptr) ____ptr = (ptr); \
858 ____ptr ? hlist_entry(____ptr, type, member) : NULL; \
859 })
860
861 /**
862 * hlist_for_each_entry - iterate over list of given type
863 * @pos: the type * to use as a loop cursor.
864 * @head: the head for your list.
865 * @member: the name of the hlist_node within the struct.
866 */
867 #define hlist_for_each_entry(pos, head, member) \
868 for (pos = hlist_entry_safe((head)->first, typeof(*(pos)), member);\
869 pos; \
870 pos = hlist_entry_safe((pos)->member.next, typeof(*(pos)), member))
871
872 /**
873 * hlist_for_each_entry_continue - iterate over a hlist continuing after current point
874 * @pos: the type * to use as a loop cursor.
875 * @member: the name of the hlist_node within the struct.
876 */
877 #define hlist_for_each_entry_continue(pos, member) \
878 for (pos = hlist_entry_safe((pos)->member.next, typeof(*(pos)), member);\
879 pos; \
880 pos = hlist_entry_safe((pos)->member.next, typeof(*(pos)), member))
881
882 /**
883 * hlist_for_each_entry_from - iterate over a hlist continuing from current point
884 * @pos: the type * to use as a loop cursor.
885 * @member: the name of the hlist_node within the struct.
886 */
887 #define hlist_for_each_entry_from(pos, member) \
888 for (; pos; \
889 pos = hlist_entry_safe((pos)->member.next, typeof(*(pos)), member))
890
891 /**
892 * hlist_for_each_entry_safe - iterate over list of given type safe against removal of list entry
893 * @pos: the type * to use as a loop cursor.
894 * @n: another &struct hlist_node to use as temporary storage
895 * @head: the head for your list.
896 * @member: the name of the hlist_node within the struct.
897 */
898 #define hlist_for_each_entry_safe(pos, n, head, member) \
899 for (pos = hlist_entry_safe((head)->first, typeof(*pos), member);\
900 pos && ({ n = pos->member.next; 1; }); \
901 pos = hlist_entry_safe(n, typeof(*pos), member))
902
903 #endif