1 | /* SPDX-License-Identifier: GPL-2.0 */ |
2 | #ifndef _LINUX_LIST_H |
3 | #define _LINUX_LIST_H |
4 | |
5 | #include <linux/container_of.h> |
6 | #include <linux/types.h> |
7 | #include <linux/stddef.h> |
8 | #include <linux/poison.h> |
9 | #include <linux/const.h> |
10 | |
11 | #include <asm/barrier.h> |
12 | |
13 | /* |
14 | * Circular doubly linked list implementation. |
15 | * |
16 | * Some of the internal functions ("__xxx") are useful when |
17 | * manipulating whole lists rather than single entries, as |
18 | * sometimes we already know the next/prev entries and we can |
19 | * generate better code by using them directly rather than |
20 | * using the generic single-entry routines. |
21 | */ |
22 | |
23 | #define LIST_HEAD_INIT(name) { &(name), &(name) } |
24 | |
25 | #define LIST_HEAD(name) \ |
26 | struct list_head name = LIST_HEAD_INIT(name) |
27 | |
28 | /** |
29 | * INIT_LIST_HEAD - Initialize a list_head structure |
30 | * @list: list_head structure to be initialized. |
31 | * |
32 | * Initializes the list_head to point to itself. If it is a list header, |
33 | * the result is an empty list. |
34 | */ |
35 | static inline void INIT_LIST_HEAD(struct list_head *list) |
36 | { |
37 | WRITE_ONCE(list->next, list); |
38 | WRITE_ONCE(list->prev, list); |
39 | } |
40 | |
41 | #ifdef CONFIG_DEBUG_LIST |
42 | extern bool __list_add_valid(struct list_head *new, |
43 | struct list_head *prev, |
44 | struct list_head *next); |
45 | extern bool __list_del_entry_valid(struct list_head *entry); |
46 | #else |
47 | static inline bool __list_add_valid(struct list_head *new, |
48 | struct list_head *prev, |
49 | struct list_head *next) |
50 | { |
51 | return true; |
52 | } |
53 | static inline bool __list_del_entry_valid(struct list_head *entry) |
54 | { |
55 | return true; |
56 | } |
57 | #endif |
58 | |
59 | /* |
60 | * Insert a new entry between two known consecutive entries. |
61 | * |
62 | * This is only for internal list manipulation where we know |
63 | * the prev/next entries already! |
64 | */ |
65 | static inline void __list_add(struct list_head *new, |
66 | struct list_head *prev, |
67 | struct list_head *next) |
68 | { |
69 | if (!__list_add_valid(new, prev, next)) |
70 | return; |
71 | |
72 | next->prev = new; |
73 | new->next = next; |
74 | new->prev = prev; |
75 | WRITE_ONCE(prev->next, new); |
76 | } |
77 | |
78 | /** |
79 | * list_add - add a new entry |
80 | * @new: new entry to be added |
81 | * @head: list head to add it after |
82 | * |
83 | * Insert a new entry after the specified head. |
84 | * This is good for implementing stacks. |
85 | */ |
86 | static inline void list_add(struct list_head *new, struct list_head *head) |
87 | { |
88 | __list_add(new, head, head->next); |
89 | } |
90 | |
91 | |
92 | /** |
93 | * list_add_tail - add a new entry |
94 | * @new: new entry to be added |
95 | * @head: list head to add it before |
96 | * |
97 | * Insert a new entry before the specified head. |
98 | * This is useful for implementing queues. |
99 | */ |
100 | static inline void list_add_tail(struct list_head *new, struct list_head *head) |
101 | { |
102 | __list_add(new, head->prev, head); |
103 | } |
104 | |
105 | /* |
106 | * Delete a list entry by making the prev/next entries |
107 | * point to each other. |
108 | * |
109 | * This is only for internal list manipulation where we know |
110 | * the prev/next entries already! |
111 | */ |
112 | static inline void __list_del(struct list_head * prev, struct list_head * next) |
113 | { |
114 | next->prev = prev; |
115 | WRITE_ONCE(prev->next, next); |
116 | } |
117 | |
118 | /* |
119 | * Delete a list entry and clear the 'prev' pointer. |
120 | * |
121 | * This is a special-purpose list clearing method used in the networking code |
122 | * for lists allocated as per-cpu, where we don't want to incur the extra |
123 | * WRITE_ONCE() overhead of a regular list_del_init(). The code that uses this |
124 | * needs to check the node 'prev' pointer instead of calling list_empty(). |
125 | */ |
126 | static inline void __list_del_clearprev(struct list_head *entry) |
127 | { |
128 | __list_del(entry->prev, entry->next); |
129 | entry->prev = NULL; |
130 | } |
131 | |
132 | static inline void __list_del_entry(struct list_head *entry) |
133 | { |
134 | if (!__list_del_entry_valid(entry)) |
135 | return; |
136 | |
137 | __list_del(entry->prev, entry->next); |
138 | } |
139 | |
140 | /** |
141 | * list_del - deletes entry from list. |
142 | * @entry: the element to delete from the list. |
143 | * Note: list_empty() on entry does not return true after this, the entry is |
144 | * in an undefined state. |
145 | */ |
146 | static inline void list_del(struct list_head *entry) |
147 | { |
148 | __list_del_entry(entry); |
149 | entry->next = LIST_POISON1; |
150 | entry->prev = LIST_POISON2; |
151 | } |
152 | |
153 | /** |
154 | * list_replace - replace old entry by new one |
155 | * @old : the element to be replaced |
156 | * @new : the new element to insert |
157 | * |
158 | * If @old was empty, it will be overwritten. |
159 | */ |
160 | static inline void list_replace(struct list_head *old, |
161 | struct list_head *new) |
162 | { |
163 | new->next = old->next; |
164 | new->next->prev = new; |
165 | new->prev = old->prev; |
166 | new->prev->next = new; |
167 | } |
168 | |
169 | /** |
170 | * list_replace_init - replace old entry by new one and initialize the old one |
171 | * @old : the element to be replaced |
172 | * @new : the new element to insert |
173 | * |
174 | * If @old was empty, it will be overwritten. |
175 | */ |
176 | static inline void list_replace_init(struct list_head *old, |
177 | struct list_head *new) |
178 | { |
179 | list_replace(old, new); |
180 | INIT_LIST_HEAD(old); |
181 | } |
182 | |
183 | /** |
184 | * list_swap - replace entry1 with entry2 and re-add entry1 at entry2's position |
185 | * @entry1: the location to place entry2 |
186 | * @entry2: the location to place entry1 |
187 | */ |
188 | static inline void list_swap(struct list_head *entry1, |
189 | struct list_head *entry2) |
190 | { |
191 | struct list_head *pos = entry2->prev; |
192 | |
193 | list_del(entry2); |
194 | list_replace(entry1, entry2); |
195 | if (pos == entry1) |
196 | pos = entry2; |
197 | list_add(entry1, pos); |
198 | } |
199 | |
200 | /** |
201 | * list_del_init - deletes entry from list and reinitialize it. |
202 | * @entry: the element to delete from the list. |
203 | */ |
204 | static inline void list_del_init(struct list_head *entry) |
205 | { |
206 | __list_del_entry(entry); |
207 | INIT_LIST_HEAD(entry); |
208 | } |
209 | |
210 | /** |
211 | * list_move - delete from one list and add as another's head |
212 | * @list: the entry to move |
213 | * @head: the head that will precede our entry |
214 | */ |
215 | static inline void list_move(struct list_head *list, struct list_head *head) |
216 | { |
217 | __list_del_entry(list); |
218 | list_add(list, head); |
219 | } |
220 | |
221 | /** |
222 | * list_move_tail - delete from one list and add as another's tail |
223 | * @list: the entry to move |
224 | * @head: the head that will follow our entry |
225 | */ |
226 | static inline void list_move_tail(struct list_head *list, |
227 | struct list_head *head) |
228 | { |
229 | __list_del_entry(list); |
230 | list_add_tail(list, head); |
231 | } |
232 | |
233 | /** |
234 | * list_bulk_move_tail - move a subsection of a list to its tail |
235 | * @head: the head that will follow our entry |
236 | * @first: first entry to move |
237 | * @last: last entry to move, can be the same as first |
238 | * |
239 | * Move all entries between @first and including @last before @head. |
240 | * All three entries must belong to the same linked list. |
241 | */ |
242 | static inline void list_bulk_move_tail(struct list_head *head, |
243 | struct list_head *first, |
244 | struct list_head *last) |
245 | { |
246 | first->prev->next = last->next; |
247 | last->next->prev = first->prev; |
248 | |
249 | head->prev->next = first; |
250 | first->prev = head->prev; |
251 | |
252 | last->next = head; |
253 | head->prev = last; |
254 | } |
255 | |
256 | /** |
257 | * list_is_first -- tests whether @list is the first entry in list @head |
258 | * @list: the entry to test |
259 | * @head: the head of the list |
260 | */ |
261 | static inline int list_is_first(const struct list_head *list, const struct list_head *head) |
262 | { |
263 | return list->prev == head; |
264 | } |
265 | |
266 | /** |
267 | * list_is_last - tests whether @list is the last entry in list @head |
268 | * @list: the entry to test |
269 | * @head: the head of the list |
270 | */ |
271 | static inline int list_is_last(const struct list_head *list, const struct list_head *head) |
272 | { |
273 | return list->next == head; |
274 | } |
275 | |
276 | /** |
277 | * list_is_head - tests whether @list is the list @head |
278 | * @list: the entry to test |
279 | * @head: the head of the list |
280 | */ |
281 | static inline int list_is_head(const struct list_head *list, const struct list_head *head) |
282 | { |
283 | return list == head; |
284 | } |
285 | |
286 | /** |
287 | * list_empty - tests whether a list is empty |
288 | * @head: the list to test. |
289 | */ |
290 | static inline int list_empty(const struct list_head *head) |
291 | { |
292 | return READ_ONCE(head->next) == head; |
293 | } |
294 | |
295 | /** |
296 | * list_del_init_careful - deletes entry from list and reinitialize it. |
297 | * @entry: the element to delete from the list. |
298 | * |
299 | * This is the same as list_del_init(), except designed to be used |
300 | * together with list_empty_careful() in a way to guarantee ordering |
301 | * of other memory operations. |
302 | * |
303 | * Any memory operations done before a list_del_init_careful() are |
304 | * guaranteed to be visible after a list_empty_careful() test. |
305 | */ |
306 | static inline void list_del_init_careful(struct list_head *entry) |
307 | { |
308 | __list_del_entry(entry); |
309 | WRITE_ONCE(entry->prev, entry); |
310 | smp_store_release(&entry->next, entry); |
311 | } |
312 | |
313 | /** |
314 | * list_empty_careful - tests whether a list is empty and not being modified |
315 | * @head: the list to test |
316 | * |
317 | * Description: |
318 | * tests whether a list is empty _and_ checks that no other CPU might be |
319 | * in the process of modifying either member (next or prev) |
320 | * |
321 | * NOTE: using list_empty_careful() without synchronization |
322 | * can only be safe if the only activity that can happen |
323 | * to the list entry is list_del_init(). Eg. it cannot be used |
324 | * if another CPU could re-list_add() it. |
325 | */ |
326 | static inline int list_empty_careful(const struct list_head *head) |
327 | { |
328 | struct list_head *next = smp_load_acquire(&head->next); |
329 | return list_is_head(next, head) && (next == READ_ONCE(head->prev)); |
330 | } |
331 | |
332 | /** |
333 | * list_rotate_left - rotate the list to the left |
334 | * @head: the head of the list |
335 | */ |
336 | static inline void list_rotate_left(struct list_head *head) |
337 | { |
338 | struct list_head *first; |
339 | |
340 | if (!list_empty(head)) { |
341 | first = head->next; |
342 | list_move_tail(first, head); |
343 | } |
344 | } |
345 | |
346 | /** |
347 | * list_rotate_to_front() - Rotate list to specific item. |
348 | * @list: The desired new front of the list. |
349 | * @head: The head of the list. |
350 | * |
351 | * Rotates list so that @list becomes the new front of the list. |
352 | */ |
353 | static inline void list_rotate_to_front(struct list_head *list, |
354 | struct list_head *head) |
355 | { |
356 | /* |
357 | * Deletes the list head from the list denoted by @head and |
358 | * places it as the tail of @list, this effectively rotates the |
359 | * list so that @list is at the front. |
360 | */ |
361 | list_move_tail(head, list); |
362 | } |
363 | |
364 | /** |
365 | * list_is_singular - tests whether a list has just one entry. |
366 | * @head: the list to test. |
367 | */ |
368 | static inline int list_is_singular(const struct list_head *head) |
369 | { |
370 | return !list_empty(head) && (head->next == head->prev); |
371 | } |
372 | |
373 | static inline void __list_cut_position(struct list_head *list, |
374 | struct list_head *head, struct list_head *entry) |
375 | { |
376 | struct list_head *new_first = entry->next; |
377 | list->next = head->next; |
378 | list->next->prev = list; |
379 | list->prev = entry; |
380 | entry->next = list; |
381 | head->next = new_first; |
382 | new_first->prev = head; |
383 | } |
384 | |
385 | /** |
386 | * list_cut_position - cut a list into two |
387 | * @list: a new list to add all removed entries |
388 | * @head: a list with entries |
389 | * @entry: an entry within head, could be the head itself |
390 | * and if so we won't cut the list |
391 | * |
392 | * This helper moves the initial part of @head, up to and |
393 | * including @entry, from @head to @list. You should |
394 | * pass on @entry an element you know is on @head. @list |
395 | * should be an empty list or a list you do not care about |
396 | * losing its data. |
397 | * |
398 | */ |
399 | static inline void list_cut_position(struct list_head *list, |
400 | struct list_head *head, struct list_head *entry) |
401 | { |
402 | if (list_empty(head)) |
403 | return; |
404 | if (list_is_singular(head) && !list_is_head(entry, head) && (entry != head->next)) |
405 | return; |
406 | if (list_is_head(entry, head)) |
407 | INIT_LIST_HEAD(list); |
408 | else |
409 | __list_cut_position(list, head, entry); |
410 | } |
411 | |
412 | /** |
413 | * list_cut_before - cut a list into two, before given entry |
414 | * @list: a new list to add all removed entries |
415 | * @head: a list with entries |
416 | * @entry: an entry within head, could be the head itself |
417 | * |
418 | * This helper moves the initial part of @head, up to but |
419 | * excluding @entry, from @head to @list. You should pass |
420 | * in @entry an element you know is on @head. @list should |
421 | * be an empty list or a list you do not care about losing |
422 | * its data. |
423 | * If @entry == @head, all entries on @head are moved to |
424 | * @list. |
425 | */ |
426 | static inline void list_cut_before(struct list_head *list, |
427 | struct list_head *head, |
428 | struct list_head *entry) |
429 | { |
430 | if (head->next == entry) { |
431 | INIT_LIST_HEAD(list); |
432 | return; |
433 | } |
434 | list->next = head->next; |
435 | list->next->prev = list; |
436 | list->prev = entry->prev; |
437 | list->prev->next = list; |
438 | head->next = entry; |
439 | entry->prev = head; |
440 | } |
441 | |
442 | static inline void __list_splice(const struct list_head *list, |
443 | struct list_head *prev, |
444 | struct list_head *next) |
445 | { |
446 | struct list_head *first = list->next; |
447 | struct list_head *last = list->prev; |
448 | |
449 | first->prev = prev; |
450 | prev->next = first; |
451 | |
452 | last->next = next; |
453 | next->prev = last; |
454 | } |
455 | |
456 | /** |
457 | * list_splice - join two lists, this is designed for stacks |
458 | * @list: the new list to add. |
459 | * @head: the place to add it in the first list. |
460 | */ |
461 | static inline void list_splice(const struct list_head *list, |
462 | struct list_head *head) |
463 | { |
464 | if (!list_empty(list)) |
465 | __list_splice(list, head, head->next); |
466 | } |
467 | |
468 | /** |
469 | * list_splice_tail - join two lists, each list being a queue |
470 | * @list: the new list to add. |
471 | * @head: the place to add it in the first list. |
472 | */ |
473 | static inline void list_splice_tail(struct list_head *list, |
474 | struct list_head *head) |
475 | { |
476 | if (!list_empty(list)) |
477 | __list_splice(list, head->prev, head); |
478 | } |
479 | |
480 | /** |
481 | * list_splice_init - join two lists and reinitialise the emptied list. |
482 | * @list: the new list to add. |
483 | * @head: the place to add it in the first list. |
484 | * |
485 | * The list at @list is reinitialised |
486 | */ |
487 | static inline void list_splice_init(struct list_head *list, |
488 | struct list_head *head) |
489 | { |
490 | if (!list_empty(list)) { |
491 | __list_splice(list, head, head->next); |
492 | INIT_LIST_HEAD(list); |
493 | } |
494 | } |
495 | |
496 | /** |
497 | * list_splice_tail_init - join two lists and reinitialise the emptied list |
498 | * @list: the new list to add. |
499 | * @head: the place to add it in the first list. |
500 | * |
501 | * Each of the lists is a queue. |
502 | * The list at @list is reinitialised |
503 | */ |
504 | static inline void list_splice_tail_init(struct list_head *list, |
505 | struct list_head *head) |
506 | { |
507 | if (!list_empty(list)) { |
508 | __list_splice(list, head->prev, head); |
509 | INIT_LIST_HEAD(list); |
510 | } |
511 | } |
512 | |
513 | /** |
514 | * list_entry - get the struct for this entry |
515 | * @ptr: the &struct list_head pointer. |
516 | * @type: the type of the struct this is embedded in. |
517 | * @member: the name of the list_head within the struct. |
518 | */ |
519 | #define list_entry(ptr, type, member) \ |
520 | container_of(ptr, type, member) |
521 | |
522 | /** |
523 | * list_first_entry - get the first element from a list |
524 | * @ptr: the list head to take the element from. |
525 | * @type: the type of the struct this is embedded in. |
526 | * @member: the name of the list_head within the struct. |
527 | * |
528 | * Note, that list is expected to be not empty. |
529 | */ |
530 | #define list_first_entry(ptr, type, member) \ |
531 | list_entry((ptr)->next, type, member) |
532 | |
533 | /** |
534 | * list_last_entry - get the last element from a list |
535 | * @ptr: the list head to take the element from. |
536 | * @type: the type of the struct this is embedded in. |
537 | * @member: the name of the list_head within the struct. |
538 | * |
539 | * Note, that list is expected to be not empty. |
540 | */ |
541 | #define list_last_entry(ptr, type, member) \ |
542 | list_entry((ptr)->prev, type, member) |
543 | |
544 | /** |
545 | * list_first_entry_or_null - get the first element from a list |
546 | * @ptr: the list head to take the element from. |
547 | * @type: the type of the struct this is embedded in. |
548 | * @member: the name of the list_head within the struct. |
549 | * |
550 | * Note that if the list is empty, it returns NULL. |
551 | */ |
552 | #define list_first_entry_or_null(ptr, type, member) ({ \ |
553 | struct list_head *head__ = (ptr); \ |
554 | struct list_head *pos__ = READ_ONCE(head__->next); \ |
555 | pos__ != head__ ? list_entry(pos__, type, member) : NULL; \ |
556 | }) |
557 | |
558 | /** |
559 | * list_next_entry - get the next element in list |
560 | * @pos: the type * to cursor |
561 | * @member: the name of the list_head within the struct. |
562 | */ |
563 | #define list_next_entry(pos, member) \ |
564 | list_entry((pos)->member.next, typeof(*(pos)), member) |
565 | |
566 | /** |
567 | * list_next_entry_circular - get the next element in list |
568 | * @pos: the type * to cursor. |
569 | * @head: the list head to take the element from. |
570 | * @member: the name of the list_head within the struct. |
571 | * |
572 | * Wraparound if pos is the last element (return the first element). |
573 | * Note, that list is expected to be not empty. |
574 | */ |
575 | #define list_next_entry_circular(pos, head, member) \ |
576 | (list_is_last(&(pos)->member, head) ? \ |
577 | list_first_entry(head, typeof(*(pos)), member) : list_next_entry(pos, member)) |
578 | |
579 | /** |
580 | * list_prev_entry - get the prev element in list |
581 | * @pos: the type * to cursor |
582 | * @member: the name of the list_head within the struct. |
583 | */ |
584 | #define list_prev_entry(pos, member) \ |
585 | list_entry((pos)->member.prev, typeof(*(pos)), member) |
586 | |
587 | /** |
588 | * list_prev_entry_circular - get the prev element in list |
589 | * @pos: the type * to cursor. |
590 | * @head: the list head to take the element from. |
591 | * @member: the name of the list_head within the struct. |
592 | * |
593 | * Wraparound if pos is the first element (return the last element). |
594 | * Note, that list is expected to be not empty. |
595 | */ |
596 | #define list_prev_entry_circular(pos, head, member) \ |
597 | (list_is_first(&(pos)->member, head) ? \ |
598 | list_last_entry(head, typeof(*(pos)), member) : list_prev_entry(pos, member)) |
599 | |
600 | /** |
601 | * list_for_each - iterate over a list |
602 | * @pos: the &struct list_head to use as a loop cursor. |
603 | * @head: the head for your list. |
604 | */ |
605 | #define list_for_each(pos, head) \ |
606 | for (pos = (head)->next; !list_is_head(pos, (head)); pos = pos->next) |
607 | |
608 | /** |
609 | * list_for_each_rcu - Iterate over a list in an RCU-safe fashion |
610 | * @pos: the &struct list_head to use as a loop cursor. |
611 | * @head: the head for your list. |
612 | */ |
613 | #define list_for_each_rcu(pos, head) \ |
614 | for (pos = rcu_dereference((head)->next); \ |
615 | !list_is_head(pos, (head)); \ |
616 | pos = rcu_dereference(pos->next)) |
617 | |
618 | /** |
619 | * list_for_each_continue - continue iteration over a list |
620 | * @pos: the &struct list_head to use as a loop cursor. |
621 | * @head: the head for your list. |
622 | * |
623 | * Continue to iterate over a list, continuing after the current position. |
624 | */ |
625 | #define list_for_each_continue(pos, head) \ |
626 | for (pos = pos->next; !list_is_head(pos, (head)); pos = pos->next) |
627 | |
628 | /** |
629 | * list_for_each_prev - iterate over a list backwards |
630 | * @pos: the &struct list_head to use as a loop cursor. |
631 | * @head: the head for your list. |
632 | */ |
633 | #define list_for_each_prev(pos, head) \ |
634 | for (pos = (head)->prev; !list_is_head(pos, (head)); pos = pos->prev) |
635 | |
636 | /** |
637 | * list_for_each_safe - iterate over a list safe against removal of list entry |
638 | * @pos: the &struct list_head to use as a loop cursor. |
639 | * @n: another &struct list_head to use as temporary storage |
640 | * @head: the head for your list. |
641 | */ |
642 | #define list_for_each_safe(pos, n, head) \ |
643 | for (pos = (head)->next, n = pos->next; \ |
644 | !list_is_head(pos, (head)); \ |
645 | pos = n, n = pos->next) |
646 | |
647 | /** |
648 | * list_for_each_prev_safe - iterate over a list backwards safe against removal of list entry |
649 | * @pos: the &struct list_head to use as a loop cursor. |
650 | * @n: another &struct list_head to use as temporary storage |
651 | * @head: the head for your list. |
652 | */ |
653 | #define list_for_each_prev_safe(pos, n, head) \ |
654 | for (pos = (head)->prev, n = pos->prev; \ |
655 | !list_is_head(pos, (head)); \ |
656 | pos = n, n = pos->prev) |
657 | |
658 | /** |
659 | * list_entry_is_head - test if the entry points to the head of the list |
660 | * @pos: the type * to cursor |
661 | * @head: the head for your list. |
662 | * @member: the name of the list_head within the struct. |
663 | */ |
664 | #define list_entry_is_head(pos, head, member) \ |
665 | (&pos->member == (head)) |
666 | |
667 | /** |
668 | * list_for_each_entry - iterate over list of given type |
669 | * @pos: the type * to use as a loop cursor. |
670 | * @head: the head for your list. |
671 | * @member: the name of the list_head within the struct. |
672 | */ |
673 | #define list_for_each_entry(pos, head, member) \ |
674 | for (pos = list_first_entry(head, typeof(*pos), member); \ |
675 | !list_entry_is_head(pos, head, member); \ |
676 | pos = list_next_entry(pos, member)) |
677 | |
678 | /** |
679 | * list_for_each_entry_reverse - iterate backwards over list of given type. |
680 | * @pos: the type * to use as a loop cursor. |
681 | * @head: the head for your list. |
682 | * @member: the name of the list_head within the struct. |
683 | */ |
684 | #define list_for_each_entry_reverse(pos, head, member) \ |
685 | for (pos = list_last_entry(head, typeof(*pos), member); \ |
686 | !list_entry_is_head(pos, head, member); \ |
687 | pos = list_prev_entry(pos, member)) |
688 | |
689 | /** |
690 | * list_prepare_entry - prepare a pos entry for use in list_for_each_entry_continue() |
691 | * @pos: the type * to use as a start point |
692 | * @head: the head of the list |
693 | * @member: the name of the list_head within the struct. |
694 | * |
695 | * Prepares a pos entry for use as a start point in list_for_each_entry_continue(). |
696 | */ |
697 | #define list_prepare_entry(pos, head, member) \ |
698 | ((pos) ? : list_entry(head, typeof(*pos), member)) |
699 | |
700 | /** |
701 | * list_for_each_entry_continue - continue iteration over list of given type |
702 | * @pos: the type * to use as a loop cursor. |
703 | * @head: the head for your list. |
704 | * @member: the name of the list_head within the struct. |
705 | * |
706 | * Continue to iterate over list of given type, continuing after |
707 | * the current position. |
708 | */ |
709 | #define list_for_each_entry_continue(pos, head, member) \ |
710 | for (pos = list_next_entry(pos, member); \ |
711 | !list_entry_is_head(pos, head, member); \ |
712 | pos = list_next_entry(pos, member)) |
713 | |
714 | /** |
715 | * list_for_each_entry_continue_reverse - iterate backwards from the given point |
716 | * @pos: the type * to use as a loop cursor. |
717 | * @head: the head for your list. |
718 | * @member: the name of the list_head within the struct. |
719 | * |
720 | * Start to iterate over list of given type backwards, continuing after |
721 | * the current position. |
722 | */ |
723 | #define list_for_each_entry_continue_reverse(pos, head, member) \ |
724 | for (pos = list_prev_entry(pos, member); \ |
725 | !list_entry_is_head(pos, head, member); \ |
726 | pos = list_prev_entry(pos, member)) |
727 | |
728 | /** |
729 | * list_for_each_entry_from - iterate over list of given type from the current point |
730 | * @pos: the type * to use as a loop cursor. |
731 | * @head: the head for your list. |
732 | * @member: the name of the list_head within the struct. |
733 | * |
734 | * Iterate over list of given type, continuing from current position. |
735 | */ |
736 | #define list_for_each_entry_from(pos, head, member) \ |
737 | for (; !list_entry_is_head(pos, head, member); \ |
738 | pos = list_next_entry(pos, member)) |
739 | |
740 | /** |
741 | * list_for_each_entry_from_reverse - iterate backwards over list of given type |
742 | * from the current point |
743 | * @pos: the type * to use as a loop cursor. |
744 | * @head: the head for your list. |
745 | * @member: the name of the list_head within the struct. |
746 | * |
747 | * Iterate backwards over list of given type, continuing from current position. |
748 | */ |
749 | #define list_for_each_entry_from_reverse(pos, head, member) \ |
750 | for (; !list_entry_is_head(pos, head, member); \ |
751 | pos = list_prev_entry(pos, member)) |
752 | |
753 | /** |
754 | * list_for_each_entry_safe - iterate over list of given type safe against removal of list entry |
755 | * @pos: the type * to use as a loop cursor. |
756 | * @n: another type * to use as temporary storage |
757 | * @head: the head for your list. |
758 | * @member: the name of the list_head within the struct. |
759 | */ |
760 | #define list_for_each_entry_safe(pos, n, head, member) \ |
761 | for (pos = list_first_entry(head, typeof(*pos), member), \ |
762 | n = list_next_entry(pos, member); \ |
763 | !list_entry_is_head(pos, head, member); \ |
764 | pos = n, n = list_next_entry(n, member)) |
765 | |
766 | /** |
767 | * list_for_each_entry_safe_continue - continue list iteration safe against removal |
768 | * @pos: the type * to use as a loop cursor. |
769 | * @n: another type * to use as temporary storage |
770 | * @head: the head for your list. |
771 | * @member: the name of the list_head within the struct. |
772 | * |
773 | * Iterate over list of given type, continuing after current point, |
774 | * safe against removal of list entry. |
775 | */ |
776 | #define list_for_each_entry_safe_continue(pos, n, head, member) \ |
777 | for (pos = list_next_entry(pos, member), \ |
778 | n = list_next_entry(pos, member); \ |
779 | !list_entry_is_head(pos, head, member); \ |
780 | pos = n, n = list_next_entry(n, member)) |
781 | |
782 | /** |
783 | * list_for_each_entry_safe_from - iterate over list from current point safe against removal |
784 | * @pos: the type * to use as a loop cursor. |
785 | * @n: another type * to use as temporary storage |
786 | * @head: the head for your list. |
787 | * @member: the name of the list_head within the struct. |
788 | * |
789 | * Iterate over list of given type from current point, safe against |
790 | * removal of list entry. |
791 | */ |
792 | #define list_for_each_entry_safe_from(pos, n, head, member) \ |
793 | for (n = list_next_entry(pos, member); \ |
794 | !list_entry_is_head(pos, head, member); \ |
795 | pos = n, n = list_next_entry(n, member)) |
796 | |
797 | /** |
798 | * list_for_each_entry_safe_reverse - iterate backwards over list safe against removal |
799 | * @pos: the type * to use as a loop cursor. |
800 | * @n: another type * to use as temporary storage |
801 | * @head: the head for your list. |
802 | * @member: the name of the list_head within the struct. |
803 | * |
804 | * Iterate backwards over list of given type, safe against removal |
805 | * of list entry. |
806 | */ |
807 | #define list_for_each_entry_safe_reverse(pos, n, head, member) \ |
808 | for (pos = list_last_entry(head, typeof(*pos), member), \ |
809 | n = list_prev_entry(pos, member); \ |
810 | !list_entry_is_head(pos, head, member); \ |
811 | pos = n, n = list_prev_entry(n, member)) |
812 | |
813 | /** |
814 | * list_safe_reset_next - reset a stale list_for_each_entry_safe loop |
815 | * @pos: the loop cursor used in the list_for_each_entry_safe loop |
816 | * @n: temporary storage used in list_for_each_entry_safe |
817 | * @member: the name of the list_head within the struct. |
818 | * |
819 | * list_safe_reset_next is not safe to use in general if the list may be |
820 | * modified concurrently (eg. the lock is dropped in the loop body). An |
821 | * exception to this is if the cursor element (pos) is pinned in the list, |
822 | * and list_safe_reset_next is called after re-taking the lock and before |
823 | * completing the current iteration of the loop body. |
824 | */ |
825 | #define list_safe_reset_next(pos, n, member) \ |
826 | n = list_next_entry(pos, member) |
827 | |
828 | /* |
829 | * Double linked lists with a single pointer list head. |
830 | * Mostly useful for hash tables where the two pointer list head is |
831 | * too wasteful. |
832 | * You lose the ability to access the tail in O(1). |
833 | */ |
834 | |
835 | #define HLIST_HEAD_INIT { .first = NULL } |
836 | #define HLIST_HEAD(name) struct hlist_head name = { .first = NULL } |
837 | #define INIT_HLIST_HEAD(ptr) ((ptr)->first = NULL) |
838 | static inline void INIT_HLIST_NODE(struct hlist_node *h) |
839 | { |
840 | h->next = NULL; |
841 | h->pprev = NULL; |
842 | } |
843 | |
844 | /** |
845 | * hlist_unhashed - Has node been removed from list and reinitialized? |
846 | * @h: Node to be checked |
847 | * |
848 | * Not that not all removal functions will leave a node in unhashed |
849 | * state. For example, hlist_nulls_del_init_rcu() does leave the |
850 | * node in unhashed state, but hlist_nulls_del() does not. |
851 | */ |
852 | static inline int hlist_unhashed(const struct hlist_node *h) |
853 | { |
854 | return !h->pprev; |
855 | } |
856 | |
857 | /** |
858 | * hlist_unhashed_lockless - Version of hlist_unhashed for lockless use |
859 | * @h: Node to be checked |
860 | * |
861 | * This variant of hlist_unhashed() must be used in lockless contexts |
862 | * to avoid potential load-tearing. The READ_ONCE() is paired with the |
863 | * various WRITE_ONCE() in hlist helpers that are defined below. |
864 | */ |
865 | static inline int hlist_unhashed_lockless(const struct hlist_node *h) |
866 | { |
867 | return !READ_ONCE(h->pprev); |
868 | } |
869 | |
870 | /** |
871 | * hlist_empty - Is the specified hlist_head structure an empty hlist? |
872 | * @h: Structure to check. |
873 | */ |
874 | static inline int hlist_empty(const struct hlist_head *h) |
875 | { |
876 | return !READ_ONCE(h->first); |
877 | } |
878 | |
879 | static inline void __hlist_del(struct hlist_node *n) |
880 | { |
881 | struct hlist_node *next = n->next; |
882 | struct hlist_node **pprev = n->pprev; |
883 | |
884 | WRITE_ONCE(*pprev, next); |
885 | if (next) |
886 | WRITE_ONCE(next->pprev, pprev); |
887 | } |
888 | |
889 | /** |
890 | * hlist_del - Delete the specified hlist_node from its list |
891 | * @n: Node to delete. |
892 | * |
893 | * Note that this function leaves the node in hashed state. Use |
894 | * hlist_del_init() or similar instead to unhash @n. |
895 | */ |
896 | static inline void hlist_del(struct hlist_node *n) |
897 | { |
898 | __hlist_del(n); |
899 | n->next = LIST_POISON1; |
900 | n->pprev = LIST_POISON2; |
901 | } |
902 | |
903 | /** |
904 | * hlist_del_init - Delete the specified hlist_node from its list and initialize |
905 | * @n: Node to delete. |
906 | * |
907 | * Note that this function leaves the node in unhashed state. |
908 | */ |
909 | static inline void hlist_del_init(struct hlist_node *n) |
910 | { |
911 | if (!hlist_unhashed(n)) { |
912 | __hlist_del(n); |
913 | INIT_HLIST_NODE(n); |
914 | } |
915 | } |
916 | |
917 | /** |
918 | * hlist_add_head - add a new entry at the beginning of the hlist |
919 | * @n: new entry to be added |
920 | * @h: hlist head to add it after |
921 | * |
922 | * Insert a new entry after the specified head. |
923 | * This is good for implementing stacks. |
924 | */ |
925 | static inline void hlist_add_head(struct hlist_node *n, struct hlist_head *h) |
926 | { |
927 | struct hlist_node *first = h->first; |
928 | WRITE_ONCE(n->next, first); |
929 | if (first) |
930 | WRITE_ONCE(first->pprev, &n->next); |
931 | WRITE_ONCE(h->first, n); |
932 | WRITE_ONCE(n->pprev, &h->first); |
933 | } |
934 | |
935 | /** |
936 | * hlist_add_before - add a new entry before the one specified |
937 | * @n: new entry to be added |
938 | * @next: hlist node to add it before, which must be non-NULL |
939 | */ |
940 | static inline void hlist_add_before(struct hlist_node *n, |
941 | struct hlist_node *next) |
942 | { |
943 | WRITE_ONCE(n->pprev, next->pprev); |
944 | WRITE_ONCE(n->next, next); |
945 | WRITE_ONCE(next->pprev, &n->next); |
946 | WRITE_ONCE(*(n->pprev), n); |
947 | } |
948 | |
949 | /** |
950 | * hlist_add_behind - add a new entry after the one specified |
951 | * @n: new entry to be added |
952 | * @prev: hlist node to add it after, which must be non-NULL |
953 | */ |
954 | static inline void hlist_add_behind(struct hlist_node *n, |
955 | struct hlist_node *prev) |
956 | { |
957 | WRITE_ONCE(n->next, prev->next); |
958 | WRITE_ONCE(prev->next, n); |
959 | WRITE_ONCE(n->pprev, &prev->next); |
960 | |
961 | if (n->next) |
962 | WRITE_ONCE(n->next->pprev, &n->next); |
963 | } |
964 | |
965 | /** |
966 | * hlist_add_fake - create a fake hlist consisting of a single headless node |
967 | * @n: Node to make a fake list out of |
968 | * |
969 | * This makes @n appear to be its own predecessor on a headless hlist. |
970 | * The point of this is to allow things like hlist_del() to work correctly |
971 | * in cases where there is no list. |
972 | */ |
973 | static inline void hlist_add_fake(struct hlist_node *n) |
974 | { |
975 | n->pprev = &n->next; |
976 | } |
977 | |
978 | /** |
979 | * hlist_fake: Is this node a fake hlist? |
980 | * @h: Node to check for being a self-referential fake hlist. |
981 | */ |
982 | static inline bool hlist_fake(struct hlist_node *h) |
983 | { |
984 | return h->pprev == &h->next; |
985 | } |
986 | |
987 | /** |
988 | * hlist_is_singular_node - is node the only element of the specified hlist? |
989 | * @n: Node to check for singularity. |
990 | * @h: Header for potentially singular list. |
991 | * |
992 | * Check whether the node is the only node of the head without |
993 | * accessing head, thus avoiding unnecessary cache misses. |
994 | */ |
995 | static inline bool |
996 | hlist_is_singular_node(struct hlist_node *n, struct hlist_head *h) |
997 | { |
998 | return !n->next && n->pprev == &h->first; |
999 | } |
1000 | |
1001 | /** |
1002 | * hlist_move_list - Move an hlist |
1003 | * @old: hlist_head for old list. |
1004 | * @new: hlist_head for new list. |
1005 | * |
1006 | * Move a list from one list head to another. Fixup the pprev |
1007 | * reference of the first entry if it exists. |
1008 | */ |
1009 | static inline void hlist_move_list(struct hlist_head *old, |
1010 | struct hlist_head *new) |
1011 | { |
1012 | new->first = old->first; |
1013 | if (new->first) |
1014 | new->first->pprev = &new->first; |
1015 | old->first = NULL; |
1016 | } |
1017 | |
1018 | #define hlist_entry(ptr, type, member) container_of(ptr,type,member) |
1019 | |
1020 | #define hlist_for_each(pos, head) \ |
1021 | for (pos = (head)->first; pos ; pos = pos->next) |
1022 | |
1023 | #define hlist_for_each_safe(pos, n, head) \ |
1024 | for (pos = (head)->first; pos && ({ n = pos->next; 1; }); \ |
1025 | pos = n) |
1026 | |
1027 | #define hlist_entry_safe(ptr, type, member) \ |
1028 | ({ typeof(ptr) ____ptr = (ptr); \ |
1029 | ____ptr ? hlist_entry(____ptr, type, member) : NULL; \ |
1030 | }) |
1031 | |
1032 | /** |
1033 | * hlist_for_each_entry - iterate over list of given type |
1034 | * @pos: the type * to use as a loop cursor. |
1035 | * @head: the head for your list. |
1036 | * @member: the name of the hlist_node within the struct. |
1037 | */ |
1038 | #define hlist_for_each_entry(pos, head, member) \ |
1039 | for (pos = hlist_entry_safe((head)->first, typeof(*(pos)), member);\ |
1040 | pos; \ |
1041 | pos = hlist_entry_safe((pos)->member.next, typeof(*(pos)), member)) |
1042 | |
1043 | /** |
1044 | * hlist_for_each_entry_continue - iterate over a hlist continuing after current point |
1045 | * @pos: the type * to use as a loop cursor. |
1046 | * @member: the name of the hlist_node within the struct. |
1047 | */ |
1048 | #define hlist_for_each_entry_continue(pos, member) \ |
1049 | for (pos = hlist_entry_safe((pos)->member.next, typeof(*(pos)), member);\ |
1050 | pos; \ |
1051 | pos = hlist_entry_safe((pos)->member.next, typeof(*(pos)), member)) |
1052 | |
1053 | /** |
1054 | * hlist_for_each_entry_from - iterate over a hlist continuing from current point |
1055 | * @pos: the type * to use as a loop cursor. |
1056 | * @member: the name of the hlist_node within the struct. |
1057 | */ |
1058 | #define hlist_for_each_entry_from(pos, member) \ |
1059 | for (; pos; \ |
1060 | pos = hlist_entry_safe((pos)->member.next, typeof(*(pos)), member)) |
1061 | |
1062 | /** |
1063 | * hlist_for_each_entry_safe - iterate over list of given type safe against removal of list entry |
1064 | * @pos: the type * to use as a loop cursor. |
1065 | * @n: a &struct hlist_node to use as temporary storage |
1066 | * @head: the head for your list. |
1067 | * @member: the name of the hlist_node within the struct. |
1068 | */ |
1069 | #define hlist_for_each_entry_safe(pos, n, head, member) \ |
1070 | for (pos = hlist_entry_safe((head)->first, typeof(*pos), member);\ |
1071 | pos && ({ n = pos->member.next; 1; }); \ |
1072 | pos = hlist_entry_safe(n, typeof(*pos), member)) |
1073 | |
1074 | #endif |
1075 | |