1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef __TOOLS_LINUX_LIST_H
3 #define __TOOLS_LINUX_LIST_H
4
5 #include <linux/types.h>
6 #include <linux/poison.h>
7 #include <linux/kernel.h>
8 #include <linux/compiler.h>
9
10 /*
11 * Simple doubly linked list implementation.
12 *
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.
18 */
19
20 #define LIST_HEAD_INIT(name) { &(name), &(name) }
21
22 #define LIST_HEAD(name) \
23 struct list_head name = LIST_HEAD_INIT(name)
24
25 static inline void INIT_LIST_HEAD(struct list_head *list)
26 {
27 list->next = list;
28 list->prev = list;
29 }
30
31 /*
32 * Insert a new entry between two known consecutive entries.
33 *
34 * This is only for internal list manipulation where we know
35 * the prev/next entries already!
36 */
37 #ifndef CONFIG_DEBUG_LIST
38 static inline void __list_add(struct list_head *new,
39 struct list_head *prev,
40 struct list_head *next)
41 {
42 next->prev = new;
43 new->next = next;
44 new->prev = prev;
45 prev->next = new;
46 }
47 #else
48 extern void __list_add(struct list_head *new,
49 struct list_head *prev,
50 struct list_head *next);
51 #endif
52
53 /**
54 * list_add - add a new entry
55 * @new: new entry to be added
56 * @head: list head to add it after
57 *
58 * Insert a new entry after the specified head.
59 * This is good for implementing stacks.
60 */
61 static inline void list_add(struct list_head *new, struct list_head *head)
62 {
63 __list_add(new, head, head->next);
64 }
65
66
67 /**
68 * list_add_tail - add a new entry
69 * @new: new entry to be added
70 * @head: list head to add it before
71 *
72 * Insert a new entry before the specified head.
73 * This is useful for implementing queues.
74 */
75 static inline void list_add_tail(struct list_head *new, struct list_head *head)
76 {
77 __list_add(new, head->prev, head);
78 }
79
80 /*
81 * Delete a list entry by making the prev/next entries
82 * point to each other.
83 *
84 * This is only for internal list manipulation where we know
85 * the prev/next entries already!
86 */
87 static inline void __list_del(struct list_head * prev, struct list_head * next)
88 {
89 next->prev = prev;
90 WRITE_ONCE(prev->next, next);
91 }
92
93 /**
94 * list_del - deletes entry from list.
95 * @entry: the element to delete from the list.
96 * Note: list_empty() on entry does not return true after this, the entry is
97 * in an undefined state.
98 */
99 #ifndef CONFIG_DEBUG_LIST
100 static inline void __list_del_entry(struct list_head *entry)
101 {
102 __list_del(entry->prev, entry->next);
103 }
104
105 static inline void list_del(struct list_head *entry)
106 {
107 __list_del(entry->prev, entry->next);
108 entry->next = LIST_POISON1;
109 entry->prev = LIST_POISON2;
110 }
111 #else
112 extern void __list_del_entry(struct list_head *entry);
113 extern void list_del(struct list_head *entry);
114 #endif
115
116 /**
117 * list_replace - replace old entry by new one
118 * @old : the element to be replaced
119 * @new : the new element to insert
120 *
121 * If @old was empty, it will be overwritten.
122 */
123 static inline void list_replace(struct list_head *old,
124 struct list_head *new)
125 {
126 new->next = old->next;
127 new->next->prev = new;
128 new->prev = old->prev;
129 new->prev->next = new;
130 }
131
132 static inline void list_replace_init(struct list_head *old,
133 struct list_head *new)
134 {
135 list_replace(old, new);
136 INIT_LIST_HEAD(old);
137 }
138
139 /**
140 * list_del_init - deletes entry from list and reinitialize it.
141 * @entry: the element to delete from the list.
142 */
143 static inline void list_del_init(struct list_head *entry)
144 {
145 __list_del_entry(entry);
146 INIT_LIST_HEAD(entry);
147 }
148
149 /**
150 * list_move - delete from one list and add as another's head
151 * @list: the entry to move
152 * @head: the head that will precede our entry
153 */
154 static inline void list_move(struct list_head *list, struct list_head *head)
155 {
156 __list_del_entry(list);
157 list_add(list, head);
158 }
159
160 /**
161 * list_move_tail - delete from one list and add as another's tail
162 * @list: the entry to move
163 * @head: the head that will follow our entry
164 */
165 static inline void list_move_tail(struct list_head *list,
166 struct list_head *head)
167 {
168 __list_del_entry(list);
169 list_add_tail(list, head);
170 }
171
172 /**
173 * list_is_last - tests whether @list is the last entry in list @head
174 * @list: the entry to test
175 * @head: the head of the list
176 */
177 static inline int list_is_last(const struct list_head *list,
178 const struct list_head *head)
179 {
180 return list->next == head;
181 }
182
183 /**
184 * list_empty - tests whether a list is empty
185 * @head: the list to test.
186 */
187 static inline int list_empty(const struct list_head *head)
188 {
189 return head->next == head;
190 }
191
192 /**
193 * list_empty_careful - tests whether a list is empty and not being modified
194 * @head: the list to test
195 *
196 * Description:
197 * tests whether a list is empty _and_ checks that no other CPU might be
198 * in the process of modifying either member (next or prev)
199 *
200 * NOTE: using list_empty_careful() without synchronization
201 * can only be safe if the only activity that can happen
202 * to the list entry is list_del_init(). Eg. it cannot be used
203 * if another CPU could re-list_add() it.
204 */
205 static inline int list_empty_careful(const struct list_head *head)
206 {
207 struct list_head *next = head->next;
208 return (next == head) && (next == head->prev);
209 }
210
211 /**
212 * list_rotate_left - rotate the list to the left
213 * @head: the head of the list
214 */
215 static inline void list_rotate_left(struct list_head *head)
216 {
217 struct list_head *first;
218
219 if (!list_empty(head)) {
220 first = head->next;
221 list_move_tail(first, head);
222 }
223 }
224
225 /**
226 * list_is_singular - tests whether a list has just one entry.
227 * @head: the list to test.
228 */
229 static inline int list_is_singular(const struct list_head *head)
230 {
231 return !list_empty(head) && (head->next == head->prev);
232 }
233
234 static inline void __list_cut_position(struct list_head *list,
235 struct list_head *head, struct list_head *entry)
236 {
237 struct list_head *new_first = entry->next;
238 list->next = head->next;
239 list->next->prev = list;
240 list->prev = entry;
241 entry->next = list;
242 head->next = new_first;
243 new_first->prev = head;
244 }
245
246 /**
247 * list_cut_position - cut a list into two
248 * @list: a new list to add all removed entries
249 * @head: a list with entries
250 * @entry: an entry within head, could be the head itself
251 * and if so we won't cut the list
252 *
253 * This helper moves the initial part of @head, up to and
254 * including @entry, from @head to @list. You should
255 * pass on @entry an element you know is on @head. @list
256 * should be an empty list or a list you do not care about
257 * losing its data.
258 *
259 */
260 static inline void list_cut_position(struct list_head *list,
261 struct list_head *head, struct list_head *entry)
262 {
263 if (list_empty(head))
264 return;
265 if (list_is_singular(head) &&
266 (head->next != entry && head != entry))
267 return;
268 if (entry == head)
269 INIT_LIST_HEAD(list);
270 else
271 __list_cut_position(list, head, entry);
272 }
273
274 static inline void __list_splice(const struct list_head *list,
275 struct list_head *prev,
276 struct list_head *next)
277 {
278 struct list_head *first = list->next;
279 struct list_head *last = list->prev;
280
281 first->prev = prev;
282 prev->next = first;
283
284 last->next = next;
285 next->prev = last;
286 }
287
288 /**
289 * list_splice - join two lists, this is designed for stacks
290 * @list: the new list to add.
291 * @head: the place to add it in the first list.
292 */
293 static inline void list_splice(const struct list_head *list,
294 struct list_head *head)
295 {
296 if (!list_empty(list))
297 __list_splice(list, head, head->next);
298 }
299
300 /**
301 * list_splice_tail - join two lists, each list being a queue
302 * @list: the new list to add.
303 * @head: the place to add it in the first list.
304 */
305 static inline void list_splice_tail(struct list_head *list,
306 struct list_head *head)
307 {
308 if (!list_empty(list))
309 __list_splice(list, head->prev, head);
310 }
311
312 /**
313 * list_splice_init - join two lists and reinitialise the emptied list.
314 * @list: the new list to add.
315 * @head: the place to add it in the first list.
316 *
317 * The list at @list is reinitialised
318 */
319 static inline void list_splice_init(struct list_head *list,
320 struct list_head *head)
321 {
322 if (!list_empty(list)) {
323 __list_splice(list, head, head->next);
324 INIT_LIST_HEAD(list);
325 }
326 }
327
328 /**
329 * list_splice_tail_init - join two lists and reinitialise the emptied list
330 * @list: the new list to add.
331 * @head: the place to add it in the first list.
332 *
333 * Each of the lists is a queue.
334 * The list at @list is reinitialised
335 */
336 static inline void list_splice_tail_init(struct list_head *list,
337 struct list_head *head)
338 {
339 if (!list_empty(list)) {
340 __list_splice(list, head->prev, head);
341 INIT_LIST_HEAD(list);
342 }
343 }
344
345 /**
346 * list_entry - get the struct for this entry
347 * @ptr: the &struct list_head pointer.
348 * @type: the type of the struct this is embedded in.
349 * @member: the name of the list_head within the struct.
350 */
351 #define list_entry(ptr, type, member) \
352 container_of(ptr, type, member)
353
354 /**
355 * list_first_entry - get the first element from a list
356 * @ptr: the list head to take the element from.
357 * @type: the type of the struct this is embedded in.
358 * @member: the name of the list_head within the struct.
359 *
360 * Note, that list is expected to be not empty.
361 */
362 #define list_first_entry(ptr, type, member) \
363 list_entry((ptr)->next, type, member)
364
365 /**
366 * list_last_entry - get the last element from a list
367 * @ptr: the list head to take the element from.
368 * @type: the type of the struct this is embedded in.
369 * @member: the name of the list_head within the struct.
370 *
371 * Note, that list is expected to be not empty.
372 */
373 #define list_last_entry(ptr, type, member) \
374 list_entry((ptr)->prev, type, member)
375
376 /**
377 * list_first_entry_or_null - get the first element from a list
378 * @ptr: the list head to take the element from.
379 * @type: the type of the struct this is embedded in.
380 * @member: the name of the list_head within the struct.
381 *
382 * Note that if the list is empty, it returns NULL.
383 */
384 #define list_first_entry_or_null(ptr, type, member) \
385 (!list_empty(ptr) ? list_first_entry(ptr, type, member) : NULL)
386
387 /**
388 * list_next_entry - get the next element in list
389 * @pos: the type * to cursor
390 * @member: the name of the list_head within the struct.
391 */
392 #define list_next_entry(pos, member) \
393 list_entry((pos)->member.next, typeof(*(pos)), member)
394
395 /**
396 * list_prev_entry - get the prev element in list
397 * @pos: the type * to cursor
398 * @member: the name of the list_head within the struct.
399 */
400 #define list_prev_entry(pos, member) \
401 list_entry((pos)->member.prev, typeof(*(pos)), member)
402
403 /**
404 * list_for_each - iterate over a list
405 * @pos: the &struct list_head to use as a loop cursor.
406 * @head: the head for your list.
407 */
408 #define list_for_each(pos, head) \
409 for (pos = (head)->next; pos != (head); pos = pos->next)
410
411 /**
412 * list_for_each_prev - iterate over a list backwards
413 * @pos: the &struct list_head to use as a loop cursor.
414 * @head: the head for your list.
415 */
416 #define list_for_each_prev(pos, head) \
417 for (pos = (head)->prev; pos != (head); pos = pos->prev)
418
419 /**
420 * list_for_each_safe - iterate over a list safe against removal of list entry
421 * @pos: the &struct list_head to use as a loop cursor.
422 * @n: another &struct list_head to use as temporary storage
423 * @head: the head for your list.
424 */
425 #define list_for_each_safe(pos, n, head) \
426 for (pos = (head)->next, n = pos->next; pos != (head); \
427 pos = n, n = pos->next)
428
429 /**
430 * list_for_each_prev_safe - iterate over a list backwards safe against removal of list entry
431 * @pos: the &struct list_head to use as a loop cursor.
432 * @n: another &struct list_head to use as temporary storage
433 * @head: the head for your list.
434 */
435 #define list_for_each_prev_safe(pos, n, head) \
436 for (pos = (head)->prev, n = pos->prev; \
437 pos != (head); \
438 pos = n, n = pos->prev)
439
440 /**
441 * list_for_each_entry - iterate over list of given type
442 * @pos: the type * to use as a loop cursor.
443 * @head: the head for your list.
444 * @member: the name of the list_head within the struct.
445 */
446 #define list_for_each_entry(pos, head, member) \
447 for (pos = list_first_entry(head, typeof(*pos), member); \
448 &pos->member != (head); \
449 pos = list_next_entry(pos, member))
450
451 /**
452 * list_for_each_entry_reverse - iterate backwards over list of given type.
453 * @pos: the type * to use as a loop cursor.
454 * @head: the head for your list.
455 * @member: the name of the list_head within the struct.
456 */
457 #define list_for_each_entry_reverse(pos, head, member) \
458 for (pos = list_last_entry(head, typeof(*pos), member); \
459 &pos->member != (head); \
460 pos = list_prev_entry(pos, member))
461
462 /**
463 * list_prepare_entry - prepare a pos entry for use in list_for_each_entry_continue()
464 * @pos: the type * to use as a start point
465 * @head: the head of the list
466 * @member: the name of the list_head within the struct.
467 *
468 * Prepares a pos entry for use as a start point in list_for_each_entry_continue().
469 */
470 #define list_prepare_entry(pos, head, member) \
471 ((pos) ? : list_entry(head, typeof(*pos), member))
472
473 /**
474 * list_for_each_entry_continue - continue iteration over list of given type
475 * @pos: the type * to use as a loop cursor.
476 * @head: the head for your list.
477 * @member: the name of the list_head within the struct.
478 *
479 * Continue to iterate over list of given type, continuing after
480 * the current position.
481 */
482 #define list_for_each_entry_continue(pos, head, member) \
483 for (pos = list_next_entry(pos, member); \
484 &pos->member != (head); \
485 pos = list_next_entry(pos, member))
486
487 /**
488 * list_for_each_entry_continue_reverse - iterate backwards from the given point
489 * @pos: the type * to use as a loop cursor.
490 * @head: the head for your list.
491 * @member: the name of the list_head within the struct.
492 *
493 * Start to iterate over list of given type backwards, continuing after
494 * the current position.
495 */
496 #define list_for_each_entry_continue_reverse(pos, head, member) \
497 for (pos = list_prev_entry(pos, member); \
498 &pos->member != (head); \
499 pos = list_prev_entry(pos, member))
500
501 /**
502 * list_for_each_entry_from - iterate over list of given type from the current point
503 * @pos: the type * to use as a loop cursor.
504 * @head: the head for your list.
505 * @member: the name of the list_head within the struct.
506 *
507 * Iterate over list of given type, continuing from current position.
508 */
509 #define list_for_each_entry_from(pos, head, member) \
510 for (; &pos->member != (head); \
511 pos = list_next_entry(pos, member))
512
513 /**
514 * list_for_each_entry_safe - iterate over list of given type safe against removal of list entry
515 * @pos: the type * to use as a loop cursor.
516 * @n: another type * to use as temporary storage
517 * @head: the head for your list.
518 * @member: the name of the list_head within the struct.
519 */
520 #define list_for_each_entry_safe(pos, n, head, member) \
521 for (pos = list_first_entry(head, typeof(*pos), member), \
522 n = list_next_entry(pos, member); \
523 &pos->member != (head); \
524 pos = n, n = list_next_entry(n, member))
525
526 /**
527 * list_for_each_entry_safe_continue - continue list iteration safe against removal
528 * @pos: the type * to use as a loop cursor.
529 * @n: another type * to use as temporary storage
530 * @head: the head for your list.
531 * @member: the name of the list_head within the struct.
532 *
533 * Iterate over list of given type, continuing after current point,
534 * safe against removal of list entry.
535 */
536 #define list_for_each_entry_safe_continue(pos, n, head, member) \
537 for (pos = list_next_entry(pos, member), \
538 n = list_next_entry(pos, member); \
539 &pos->member != (head); \
540 pos = n, n = list_next_entry(n, member))
541
542 /**
543 * list_for_each_entry_safe_from - iterate over list from current point safe against removal
544 * @pos: the type * to use as a loop cursor.
545 * @n: another type * to use as temporary storage
546 * @head: the head for your list.
547 * @member: the name of the list_head within the struct.
548 *
549 * Iterate over list of given type from current point, safe against
550 * removal of list entry.
551 */
552 #define list_for_each_entry_safe_from(pos, n, head, member) \
553 for (n = list_next_entry(pos, member); \
554 &pos->member != (head); \
555 pos = n, n = list_next_entry(n, member))
556
557 /**
558 * list_for_each_entry_safe_reverse - iterate backwards over list safe against removal
559 * @pos: the type * to use as a loop cursor.
560 * @n: another type * to use as temporary storage
561 * @head: the head for your list.
562 * @member: the name of the list_head within the struct.
563 *
564 * Iterate backwards over list of given type, safe against removal
565 * of list entry.
566 */
567 #define list_for_each_entry_safe_reverse(pos, n, head, member) \
568 for (pos = list_last_entry(head, typeof(*pos), member), \
569 n = list_prev_entry(pos, member); \
570 &pos->member != (head); \
571 pos = n, n = list_prev_entry(n, member))
572
573 /**
574 * list_safe_reset_next - reset a stale list_for_each_entry_safe loop
575 * @pos: the loop cursor used in the list_for_each_entry_safe loop
576 * @n: temporary storage used in list_for_each_entry_safe
577 * @member: the name of the list_head within the struct.
578 *
579 * list_safe_reset_next is not safe to use in general if the list may be
580 * modified concurrently (eg. the lock is dropped in the loop body). An
581 * exception to this is if the cursor element (pos) is pinned in the list,
582 * and list_safe_reset_next is called after re-taking the lock and before
583 * completing the current iteration of the loop body.
584 */
585 #define list_safe_reset_next(pos, n, member) \
586 n = list_next_entry(pos, member)
587
588 /*
589 * Double linked lists with a single pointer list head.
590 * Mostly useful for hash tables where the two pointer list head is
591 * too wasteful.
592 * You lose the ability to access the tail in O(1).
593 */
594
595 #define HLIST_HEAD_INIT { .first = NULL }
596 #define HLIST_HEAD(name) struct hlist_head name = { .first = NULL }
597 #define INIT_HLIST_HEAD(ptr) ((ptr)->first = NULL)
598 static inline void INIT_HLIST_NODE(struct hlist_node *h)
599 {
600 h->next = NULL;
601 h->pprev = NULL;
602 }
603
604 static inline int hlist_unhashed(const struct hlist_node *h)
605 {
606 return !h->pprev;
607 }
608
609 static inline int hlist_empty(const struct hlist_head *h)
610 {
611 return !h->first;
612 }
613
614 static inline void __hlist_del(struct hlist_node *n)
615 {
616 struct hlist_node *next = n->next;
617 struct hlist_node **pprev = n->pprev;
618
619 WRITE_ONCE(*pprev, next);
620 if (next)
621 next->pprev = pprev;
622 }
623
624 static inline void hlist_del(struct hlist_node *n)
625 {
626 __hlist_del(n);
627 n->next = LIST_POISON1;
628 n->pprev = LIST_POISON2;
629 }
630
631 static inline void hlist_del_init(struct hlist_node *n)
632 {
633 if (!hlist_unhashed(n)) {
634 __hlist_del(n);
635 INIT_HLIST_NODE(n);
636 }
637 }
638
639 static inline void hlist_add_head(struct hlist_node *n, struct hlist_head *h)
640 {
641 struct hlist_node *first = h->first;
642 n->next = first;
643 if (first)
644 first->pprev = &n->next;
645 h->first = n;
646 n->pprev = &h->first;
647 }
648
649 /* next must be != NULL */
650 static inline void hlist_add_before(struct hlist_node *n,
651 struct hlist_node *next)
652 {
653 n->pprev = next->pprev;
654 n->next = next;
655 next->pprev = &n->next;
656 *(n->pprev) = n;
657 }
658
659 static inline void hlist_add_behind(struct hlist_node *n,
660 struct hlist_node *prev)
661 {
662 n->next = prev->next;
663 prev->next = n;
664 n->pprev = &prev->next;
665
666 if (n->next)
667 n->next->pprev = &n->next;
668 }
669
670 /* after that we'll appear to be on some hlist and hlist_del will work */
671 static inline void hlist_add_fake(struct hlist_node *n)
672 {
673 n->pprev = &n->next;
674 }
675
676 static inline bool hlist_fake(struct hlist_node *h)
677 {
678 return h->pprev == &h->next;
679 }
680
681 /*
682 * Move a list from one list head to another. Fixup the pprev
683 * reference of the first entry if it exists.
684 */
685 static inline void hlist_move_list(struct hlist_head *old,
686 struct hlist_head *new)
687 {
688 new->first = old->first;
689 if (new->first)
690 new->first->pprev = &new->first;
691 old->first = NULL;
692 }
693
694 #define hlist_entry(ptr, type, member) container_of(ptr,type,member)
695
696 #define hlist_for_each(pos, head) \
697 for (pos = (head)->first; pos ; pos = pos->next)
698
699 #define hlist_for_each_safe(pos, n, head) \
700 for (pos = (head)->first; pos && ({ n = pos->next; 1; }); \
701 pos = n)
702
703 #define hlist_entry_safe(ptr, type, member) \
704 ({ typeof(ptr) ____ptr = (ptr); \
705 ____ptr ? hlist_entry(____ptr, type, member) : NULL; \
706 })
707
708 /**
709 * hlist_for_each_entry - iterate over list of given type
710 * @pos: the type * to use as a loop cursor.
711 * @head: the head for your list.
712 * @member: the name of the hlist_node within the struct.
713 */
714 #define hlist_for_each_entry(pos, head, member) \
715 for (pos = hlist_entry_safe((head)->first, typeof(*(pos)), member);\
716 pos; \
717 pos = hlist_entry_safe((pos)->member.next, typeof(*(pos)), member))
718
719 /**
720 * hlist_for_each_entry_continue - iterate over a hlist continuing after current point
721 * @pos: the type * to use as a loop cursor.
722 * @member: the name of the hlist_node within the struct.
723 */
724 #define hlist_for_each_entry_continue(pos, member) \
725 for (pos = hlist_entry_safe((pos)->member.next, typeof(*(pos)), member);\
726 pos; \
727 pos = hlist_entry_safe((pos)->member.next, typeof(*(pos)), member))
728
729 /**
730 * hlist_for_each_entry_from - iterate over a hlist continuing from current point
731 * @pos: the type * to use as a loop cursor.
732 * @member: the name of the hlist_node within the struct.
733 */
734 #define hlist_for_each_entry_from(pos, member) \
735 for (; pos; \
736 pos = hlist_entry_safe((pos)->member.next, typeof(*(pos)), member))
737
738 /**
739 * hlist_for_each_entry_safe - iterate over list of given type safe against removal of list entry
740 * @pos: the type * to use as a loop cursor.
741 * @n: another &struct hlist_node to use as temporary storage
742 * @head: the head for your list.
743 * @member: the name of the hlist_node within the struct.
744 */
745 #define hlist_for_each_entry_safe(pos, n, head, member) \
746 for (pos = hlist_entry_safe((head)->first, typeof(*pos), member);\
747 pos && ({ n = pos->member.next; 1; }); \
748 pos = hlist_entry_safe(n, typeof(*pos), member))
749
750 /**
751 * list_del_range - deletes range of entries from list.
752 * @begin: first element in the range to delete from the list.
753 * @end: last element in the range to delete from the list.
754 * Note: list_empty on the range of entries does not return true after this,
755 * the entries is in an undefined state.
756 */
757 static inline void list_del_range(struct list_head *begin,
758 struct list_head *end)
759 {
760 begin->prev->next = end->next;
761 end->next->prev = begin->prev;
762 }
763
764 /**
765 * list_for_each_from - iterate over a list from one of its nodes
766 * @pos: the &struct list_head to use as a loop cursor, from where to start
767 * @head: the head for your list.
768 */
769 #define list_for_each_from(pos, head) \
770 for (; pos != (head); pos = pos->next)
771
772 #endif /* __TOOLS_LINUX_LIST_H */