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Linus Torvalds1da177e2005-04-16 15:20:36 -07001#ifndef _LINUX_LIST_H
2#define _LINUX_LIST_H
3
Chris Metcalfde5d9bf2010-07-02 13:41:14 -04004#include <linux/types.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -07005#include <linux/stddef.h>
Randy Dunlapc9cf5522006-06-27 02:53:52 -07006#include <linux/poison.h>
Linus Torvaldse66eed62011-05-19 14:15:29 -07007#include <linux/const.h>
Masahiro Yamada8b21d9c2014-10-13 15:51:30 -07008#include <linux/kernel.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -07009
10/*
Linus Torvalds1da177e2005-04-16 15:20:36 -070011 * 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
Linus Torvalds1da177e2005-04-16 15:20:36 -070020#define LIST_HEAD_INIT(name) { &(name), &(name) }
21
22#define LIST_HEAD(name) \
23 struct list_head name = LIST_HEAD_INIT(name)
24
Zach Brown490d6ab2006-02-03 03:03:56 -080025static inline void INIT_LIST_HEAD(struct list_head *list)
26{
Paul E. McKenney2f073842015-10-12 16:56:42 -070027 WRITE_ONCE(list->next, list);
Zach Brown490d6ab2006-02-03 03:03:56 -080028 list->prev = list;
29}
Linus Torvalds1da177e2005-04-16 15:20:36 -070030
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 */
Dave Jones199a9af2006-09-29 01:59:00 -070037#ifndef CONFIG_DEBUG_LIST
Linus Torvalds1da177e2005-04-16 15:20:36 -070038static 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;
Paul E. McKenney1c97be62015-09-20 22:02:17 -070045 WRITE_ONCE(prev->next, new);
Linus Torvalds1da177e2005-04-16 15:20:36 -070046}
Dave Jones199a9af2006-09-29 01:59:00 -070047#else
48extern void __list_add(struct list_head *new,
49 struct list_head *prev,
50 struct list_head *next);
51#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -070052
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 */
61static inline void list_add(struct list_head *new, struct list_head *head)
62{
63 __list_add(new, head, head->next);
64}
Dave Jones199a9af2006-09-29 01:59:00 -070065
Linus Torvalds1da177e2005-04-16 15:20:36 -070066
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 */
75static inline void list_add_tail(struct list_head *new, struct list_head *head)
76{
77 __list_add(new, head->prev, head);
78}
79
80/*
Linus Torvalds1da177e2005-04-16 15:20:36 -070081 * 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 */
87static inline void __list_del(struct list_head * prev, struct list_head * next)
88{
89 next->prev = prev;
Paul E. McKenney7f5f8732015-09-18 08:45:22 -070090 WRITE_ONCE(prev->next, next);
Linus Torvalds1da177e2005-04-16 15:20:36 -070091}
92
93/**
94 * list_del - deletes entry from list.
95 * @entry: the element to delete from the list.
Robert P. J. Day72fd4a32007-02-10 01:45:59 -080096 * Note: list_empty() on entry does not return true after this, the entry is
Linus Torvalds1da177e2005-04-16 15:20:36 -070097 * in an undefined state.
98 */
Dave Jones199a9af2006-09-29 01:59:00 -070099#ifndef CONFIG_DEBUG_LIST
Linus Torvalds3c18d4d2011-02-18 11:32:28 -0800100static inline void __list_del_entry(struct list_head *entry)
101{
102 __list_del(entry->prev, entry->next);
103}
104
Linus Torvalds1da177e2005-04-16 15:20:36 -0700105static 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}
Dave Jones199a9af2006-09-29 01:59:00 -0700111#else
Linus Torvalds3c18d4d2011-02-18 11:32:28 -0800112extern void __list_del_entry(struct list_head *entry);
Dave Jones199a9af2006-09-29 01:59:00 -0700113extern void list_del(struct list_head *entry);
114#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -0700115
Dan Williams5c2c2582016-01-15 16:56:49 -0800116#ifdef CONFIG_DEBUG_LIST
117/*
118 * See devm_memremap_pages() which wants DEBUG_LIST=y to assert if one
119 * of the pages it allocates is ever passed to list_add()
120 */
121extern void list_force_poison(struct list_head *entry);
122#else
123/* fallback to the less strict LIST_POISON* definitions */
124#define list_force_poison list_del
125#endif
126
Linus Torvalds1da177e2005-04-16 15:20:36 -0700127/**
Oleg Nesterov54e73772006-06-23 02:05:54 -0700128 * list_replace - replace old entry by new one
129 * @old : the element to be replaced
130 * @new : the new element to insert
Robert P. J. Day72fd4a32007-02-10 01:45:59 -0800131 *
132 * If @old was empty, it will be overwritten.
Oleg Nesterov54e73772006-06-23 02:05:54 -0700133 */
134static inline void list_replace(struct list_head *old,
135 struct list_head *new)
136{
137 new->next = old->next;
138 new->next->prev = new;
139 new->prev = old->prev;
140 new->prev->next = new;
141}
142
143static inline void list_replace_init(struct list_head *old,
144 struct list_head *new)
145{
146 list_replace(old, new);
147 INIT_LIST_HEAD(old);
148}
149
Robert P. J. Day45f8bde2007-01-26 00:57:09 -0800150/**
Linus Torvalds1da177e2005-04-16 15:20:36 -0700151 * list_del_init - deletes entry from list and reinitialize it.
152 * @entry: the element to delete from the list.
153 */
154static inline void list_del_init(struct list_head *entry)
155{
Linus Torvalds3c18d4d2011-02-18 11:32:28 -0800156 __list_del_entry(entry);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700157 INIT_LIST_HEAD(entry);
158}
159
160/**
161 * list_move - delete from one list and add as another's head
162 * @list: the entry to move
163 * @head: the head that will precede our entry
164 */
165static inline void list_move(struct list_head *list, struct list_head *head)
166{
Linus Torvalds3c18d4d2011-02-18 11:32:28 -0800167 __list_del_entry(list);
Daniel Walker78db2ad2007-05-12 16:28:35 -0700168 list_add(list, head);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700169}
170
171/**
172 * list_move_tail - delete from one list and add as another's tail
173 * @list: the entry to move
174 * @head: the head that will follow our entry
175 */
176static inline void list_move_tail(struct list_head *list,
177 struct list_head *head)
178{
Linus Torvalds3c18d4d2011-02-18 11:32:28 -0800179 __list_del_entry(list);
Daniel Walker78db2ad2007-05-12 16:28:35 -0700180 list_add_tail(list, head);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700181}
182
183/**
Shailabh Nagare8f4d972006-07-14 00:24:35 -0700184 * list_is_last - tests whether @list is the last entry in list @head
185 * @list: the entry to test
186 * @head: the head of the list
187 */
188static inline int list_is_last(const struct list_head *list,
189 const struct list_head *head)
190{
191 return list->next == head;
192}
193
194/**
Linus Torvalds1da177e2005-04-16 15:20:36 -0700195 * list_empty - tests whether a list is empty
196 * @head: the list to test.
197 */
198static inline int list_empty(const struct list_head *head)
199{
Paul E. McKenney1658d352015-09-20 17:03:16 -0700200 return READ_ONCE(head->next) == head;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700201}
202
203/**
Randy Dunlapfe96e572006-06-25 05:47:42 -0700204 * list_empty_careful - tests whether a list is empty and not being modified
205 * @head: the list to test
206 *
207 * Description:
208 * tests whether a list is empty _and_ checks that no other CPU might be
209 * in the process of modifying either member (next or prev)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700210 *
211 * NOTE: using list_empty_careful() without synchronization
212 * can only be safe if the only activity that can happen
213 * to the list entry is list_del_init(). Eg. it cannot be used
214 * if another CPU could re-list_add() it.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700215 */
216static inline int list_empty_careful(const struct list_head *head)
217{
218 struct list_head *next = head->next;
219 return (next == head) && (next == head->prev);
220}
221
Masami Hiramatsu99602572008-04-28 02:14:27 -0700222/**
Frederic Weisbecker5908cdc2010-01-09 20:53:14 +0100223 * list_rotate_left - rotate the list to the left
224 * @head: the head of the list
225 */
226static inline void list_rotate_left(struct list_head *head)
227{
228 struct list_head *first;
229
230 if (!list_empty(head)) {
231 first = head->next;
232 list_move_tail(first, head);
233 }
234}
235
236/**
Masami Hiramatsu99602572008-04-28 02:14:27 -0700237 * list_is_singular - tests whether a list has just one entry.
238 * @head: the list to test.
239 */
240static inline int list_is_singular(const struct list_head *head)
241{
242 return !list_empty(head) && (head->next == head->prev);
243}
244
Luis R. Rodriguez00e8a4d2008-08-06 13:28:54 -0700245static inline void __list_cut_position(struct list_head *list,
246 struct list_head *head, struct list_head *entry)
247{
248 struct list_head *new_first = entry->next;
249 list->next = head->next;
250 list->next->prev = list;
251 list->prev = entry;
252 entry->next = list;
253 head->next = new_first;
254 new_first->prev = head;
255}
256
257/**
258 * list_cut_position - cut a list into two
259 * @list: a new list to add all removed entries
260 * @head: a list with entries
261 * @entry: an entry within head, could be the head itself
262 * and if so we won't cut the list
263 *
264 * This helper moves the initial part of @head, up to and
265 * including @entry, from @head to @list. You should
266 * pass on @entry an element you know is on @head. @list
267 * should be an empty list or a list you do not care about
268 * losing its data.
269 *
270 */
271static inline void list_cut_position(struct list_head *list,
272 struct list_head *head, struct list_head *entry)
273{
274 if (list_empty(head))
275 return;
276 if (list_is_singular(head) &&
277 (head->next != entry && head != entry))
278 return;
279 if (entry == head)
280 INIT_LIST_HEAD(list);
281 else
282 __list_cut_position(list, head, entry);
283}
284
Robert P. J. Day95d8c362008-04-29 00:59:29 -0700285static inline void __list_splice(const struct list_head *list,
Luis R. Rodriguez7d283ae2008-08-06 15:21:26 -0700286 struct list_head *prev,
287 struct list_head *next)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700288{
289 struct list_head *first = list->next;
290 struct list_head *last = list->prev;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700291
Luis R. Rodriguez7d283ae2008-08-06 15:21:26 -0700292 first->prev = prev;
293 prev->next = first;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700294
Luis R. Rodriguez7d283ae2008-08-06 15:21:26 -0700295 last->next = next;
296 next->prev = last;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700297}
298
299/**
Luis R. Rodriguez7d283ae2008-08-06 15:21:26 -0700300 * list_splice - join two lists, this is designed for stacks
Linus Torvalds1da177e2005-04-16 15:20:36 -0700301 * @list: the new list to add.
302 * @head: the place to add it in the first list.
303 */
Robert P. J. Day95d8c362008-04-29 00:59:29 -0700304static inline void list_splice(const struct list_head *list,
305 struct list_head *head)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700306{
307 if (!list_empty(list))
Luis R. Rodriguez7d283ae2008-08-06 15:21:26 -0700308 __list_splice(list, head, head->next);
309}
310
311/**
312 * list_splice_tail - join two lists, each list being a queue
313 * @list: the new list to add.
314 * @head: the place to add it in the first list.
315 */
316static inline void list_splice_tail(struct list_head *list,
317 struct list_head *head)
318{
319 if (!list_empty(list))
320 __list_splice(list, head->prev, head);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700321}
322
323/**
324 * list_splice_init - join two lists and reinitialise the emptied list.
325 * @list: the new list to add.
326 * @head: the place to add it in the first list.
327 *
328 * The list at @list is reinitialised
329 */
330static inline void list_splice_init(struct list_head *list,
331 struct list_head *head)
332{
333 if (!list_empty(list)) {
Luis R. Rodriguez7d283ae2008-08-06 15:21:26 -0700334 __list_splice(list, head, head->next);
335 INIT_LIST_HEAD(list);
336 }
337}
338
339/**
Randy Dunlap6724cce2008-08-08 13:56:20 -0700340 * list_splice_tail_init - join two lists and reinitialise the emptied list
Luis R. Rodriguez7d283ae2008-08-06 15:21:26 -0700341 * @list: the new list to add.
342 * @head: the place to add it in the first list.
343 *
Randy Dunlap6724cce2008-08-08 13:56:20 -0700344 * Each of the lists is a queue.
Luis R. Rodriguez7d283ae2008-08-06 15:21:26 -0700345 * The list at @list is reinitialised
346 */
347static inline void list_splice_tail_init(struct list_head *list,
348 struct list_head *head)
349{
350 if (!list_empty(list)) {
351 __list_splice(list, head->prev, head);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700352 INIT_LIST_HEAD(list);
353 }
354}
355
356/**
357 * list_entry - get the struct for this entry
358 * @ptr: the &struct list_head pointer.
359 * @type: the type of the struct this is embedded in.
Andrey Utkin3943f422014-11-14 05:09:55 +0400360 * @member: the name of the list_head within the struct.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700361 */
362#define list_entry(ptr, type, member) \
363 container_of(ptr, type, member)
364
365/**
Pavel Emelianovb5e61812007-05-08 00:30:19 -0700366 * list_first_entry - get the first 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.
Andrey Utkin3943f422014-11-14 05:09:55 +0400369 * @member: the name of the list_head within the struct.
Pavel Emelianovb5e61812007-05-08 00:30:19 -0700370 *
371 * Note, that list is expected to be not empty.
372 */
373#define list_first_entry(ptr, type, member) \
374 list_entry((ptr)->next, type, member)
375
376/**
Oleg Nesterov93be3c22013-11-12 15:10:03 -0800377 * list_last_entry - get the last 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.
Andrey Utkin3943f422014-11-14 05:09:55 +0400380 * @member: the name of the list_head within the struct.
Oleg Nesterov93be3c22013-11-12 15:10:03 -0800381 *
382 * Note, that list is expected to be not empty.
383 */
384#define list_last_entry(ptr, type, member) \
385 list_entry((ptr)->prev, type, member)
386
387/**
Jiri Pirko6d7581e2013-05-29 05:02:56 +0000388 * list_first_entry_or_null - get the first element from a list
389 * @ptr: the list head to take the element from.
390 * @type: the type of the struct this is embedded in.
Andrey Utkin3943f422014-11-14 05:09:55 +0400391 * @member: the name of the list_head within the struct.
Jiri Pirko6d7581e2013-05-29 05:02:56 +0000392 *
393 * Note that if the list is empty, it returns NULL.
394 */
395#define list_first_entry_or_null(ptr, type, member) \
396 (!list_empty(ptr) ? list_first_entry(ptr, type, member) : NULL)
397
398/**
Oleg Nesterov008208c2013-11-12 15:10:01 -0800399 * list_next_entry - get the next element in list
400 * @pos: the type * to cursor
Andrey Utkin3943f422014-11-14 05:09:55 +0400401 * @member: the name of the list_head within the struct.
Oleg Nesterov008208c2013-11-12 15:10:01 -0800402 */
403#define list_next_entry(pos, member) \
404 list_entry((pos)->member.next, typeof(*(pos)), member)
405
406/**
407 * list_prev_entry - get the prev element in list
408 * @pos: the type * to cursor
Andrey Utkin3943f422014-11-14 05:09:55 +0400409 * @member: the name of the list_head within the struct.
Oleg Nesterov008208c2013-11-12 15:10:01 -0800410 */
411#define list_prev_entry(pos, member) \
412 list_entry((pos)->member.prev, typeof(*(pos)), member)
413
414/**
Linus Torvalds1da177e2005-04-16 15:20:36 -0700415 * list_for_each - iterate over a list
Randy Dunlap8e3a67a2006-06-25 05:47:43 -0700416 * @pos: the &struct list_head to use as a loop cursor.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700417 * @head: the head for your list.
418 */
419#define list_for_each(pos, head) \
Linus Torvaldse66eed62011-05-19 14:15:29 -0700420 for (pos = (head)->next; pos != (head); pos = pos->next)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700421
422/**
Linus Torvalds1da177e2005-04-16 15:20:36 -0700423 * list_for_each_prev - iterate over a list backwards
Randy Dunlap8e3a67a2006-06-25 05:47:43 -0700424 * @pos: the &struct list_head to use as a loop cursor.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700425 * @head: the head for your list.
426 */
427#define list_for_each_prev(pos, head) \
Linus Torvaldse66eed62011-05-19 14:15:29 -0700428 for (pos = (head)->prev; pos != (head); pos = pos->prev)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700429
430/**
Randy Dunlapfe96e572006-06-25 05:47:42 -0700431 * list_for_each_safe - iterate over a list safe against removal of list entry
Randy Dunlap8e3a67a2006-06-25 05:47:43 -0700432 * @pos: the &struct list_head to use as a loop cursor.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700433 * @n: another &struct list_head to use as temporary storage
434 * @head: the head for your list.
435 */
436#define list_for_each_safe(pos, n, head) \
437 for (pos = (head)->next, n = pos->next; pos != (head); \
438 pos = n, n = pos->next)
439
440/**
Randy Dunlap8f731f72007-10-18 23:39:28 -0700441 * list_for_each_prev_safe - iterate over a list backwards safe against removal of list entry
Denis V. Lunev37c42522007-10-16 23:29:53 -0700442 * @pos: the &struct list_head to use as a loop cursor.
443 * @n: another &struct list_head to use as temporary storage
444 * @head: the head for your list.
445 */
446#define list_for_each_prev_safe(pos, n, head) \
447 for (pos = (head)->prev, n = pos->prev; \
Linus Torvaldse66eed62011-05-19 14:15:29 -0700448 pos != (head); \
Denis V. Lunev37c42522007-10-16 23:29:53 -0700449 pos = n, n = pos->prev)
450
451/**
Linus Torvalds1da177e2005-04-16 15:20:36 -0700452 * list_for_each_entry - iterate over list of given type
Randy Dunlap8e3a67a2006-06-25 05:47:43 -0700453 * @pos: the type * to use as a loop cursor.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700454 * @head: the head for your list.
Andrey Utkin3943f422014-11-14 05:09:55 +0400455 * @member: the name of the list_head within the struct.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700456 */
457#define list_for_each_entry(pos, head, member) \
Oleg Nesterov93be3c22013-11-12 15:10:03 -0800458 for (pos = list_first_entry(head, typeof(*pos), member); \
Oleg Nesterov8120e2e2013-11-12 15:10:02 -0800459 &pos->member != (head); \
460 pos = list_next_entry(pos, member))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700461
462/**
463 * list_for_each_entry_reverse - iterate backwards over list of given type.
Randy Dunlap8e3a67a2006-06-25 05:47:43 -0700464 * @pos: the type * to use as a loop cursor.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700465 * @head: the head for your list.
Andrey Utkin3943f422014-11-14 05:09:55 +0400466 * @member: the name of the list_head within the struct.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700467 */
468#define list_for_each_entry_reverse(pos, head, member) \
Oleg Nesterov93be3c22013-11-12 15:10:03 -0800469 for (pos = list_last_entry(head, typeof(*pos), member); \
Oleg Nesterov8120e2e2013-11-12 15:10:02 -0800470 &pos->member != (head); \
471 pos = list_prev_entry(pos, member))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700472
473/**
Robert P. J. Day72fd4a32007-02-10 01:45:59 -0800474 * list_prepare_entry - prepare a pos entry for use in list_for_each_entry_continue()
Linus Torvalds1da177e2005-04-16 15:20:36 -0700475 * @pos: the type * to use as a start point
476 * @head: the head of the list
Andrey Utkin3943f422014-11-14 05:09:55 +0400477 * @member: the name of the list_head within the struct.
Randy Dunlapfe96e572006-06-25 05:47:42 -0700478 *
Robert P. J. Day72fd4a32007-02-10 01:45:59 -0800479 * Prepares a pos entry for use as a start point in list_for_each_entry_continue().
Linus Torvalds1da177e2005-04-16 15:20:36 -0700480 */
481#define list_prepare_entry(pos, head, member) \
482 ((pos) ? : list_entry(head, typeof(*pos), member))
483
484/**
Randy Dunlapfe96e572006-06-25 05:47:42 -0700485 * list_for_each_entry_continue - continue iteration over list of given type
Randy Dunlap8e3a67a2006-06-25 05:47:43 -0700486 * @pos: the type * to use as a loop cursor.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700487 * @head: the head for your list.
Andrey Utkin3943f422014-11-14 05:09:55 +0400488 * @member: the name of the list_head within the struct.
Randy Dunlapfe96e572006-06-25 05:47:42 -0700489 *
490 * Continue to iterate over list of given type, continuing after
491 * the current position.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700492 */
493#define list_for_each_entry_continue(pos, head, member) \
Oleg Nesterov8120e2e2013-11-12 15:10:02 -0800494 for (pos = list_next_entry(pos, member); \
495 &pos->member != (head); \
496 pos = list_next_entry(pos, member))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700497
498/**
Pavel Emelyanov768f35912007-09-18 13:20:41 -0700499 * list_for_each_entry_continue_reverse - iterate backwards from the given point
500 * @pos: the type * to use as a loop cursor.
501 * @head: the head for your list.
Andrey Utkin3943f422014-11-14 05:09:55 +0400502 * @member: the name of the list_head within the struct.
Pavel Emelyanov768f35912007-09-18 13:20:41 -0700503 *
504 * Start to iterate over list of given type backwards, continuing after
505 * the current position.
506 */
507#define list_for_each_entry_continue_reverse(pos, head, member) \
Oleg Nesterov8120e2e2013-11-12 15:10:02 -0800508 for (pos = list_prev_entry(pos, member); \
509 &pos->member != (head); \
510 pos = list_prev_entry(pos, member))
Pavel Emelyanov768f35912007-09-18 13:20:41 -0700511
512/**
Randy Dunlapfe96e572006-06-25 05:47:42 -0700513 * list_for_each_entry_from - iterate over list of given type from the current point
Randy Dunlap8e3a67a2006-06-25 05:47:43 -0700514 * @pos: the type * to use as a loop cursor.
Arnaldo Carvalho de Meloe229c2f2006-03-20 17:19:17 -0800515 * @head: the head for your list.
Andrey Utkin3943f422014-11-14 05:09:55 +0400516 * @member: the name of the list_head within the struct.
Randy Dunlapfe96e572006-06-25 05:47:42 -0700517 *
518 * Iterate over list of given type, continuing from current position.
Arnaldo Carvalho de Meloe229c2f2006-03-20 17:19:17 -0800519 */
520#define list_for_each_entry_from(pos, head, member) \
Oleg Nesterov8120e2e2013-11-12 15:10:02 -0800521 for (; &pos->member != (head); \
522 pos = list_next_entry(pos, member))
Arnaldo Carvalho de Meloe229c2f2006-03-20 17:19:17 -0800523
524/**
Linus Torvalds1da177e2005-04-16 15:20:36 -0700525 * list_for_each_entry_safe - iterate over list of given type safe against removal of list entry
Randy Dunlap8e3a67a2006-06-25 05:47:43 -0700526 * @pos: the type * to use as a loop cursor.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700527 * @n: another type * to use as temporary storage
528 * @head: the head for your list.
Andrey Utkin3943f422014-11-14 05:09:55 +0400529 * @member: the name of the list_head within the struct.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700530 */
531#define list_for_each_entry_safe(pos, n, head, member) \
Oleg Nesterov93be3c22013-11-12 15:10:03 -0800532 for (pos = list_first_entry(head, typeof(*pos), member), \
Oleg Nesterov8120e2e2013-11-12 15:10:02 -0800533 n = list_next_entry(pos, member); \
Linus Torvalds1da177e2005-04-16 15:20:36 -0700534 &pos->member != (head); \
Oleg Nesterov8120e2e2013-11-12 15:10:02 -0800535 pos = n, n = list_next_entry(n, member))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700536
537/**
Ben Hutchings9a86e2b2010-03-05 13:43:17 -0800538 * list_for_each_entry_safe_continue - continue list iteration safe against removal
Randy Dunlap8e3a67a2006-06-25 05:47:43 -0700539 * @pos: the type * to use as a loop cursor.
Arnaldo Carvalho de Melo74459dc2005-08-09 20:15:51 -0700540 * @n: another type * to use as temporary storage
541 * @head: the head for your list.
Andrey Utkin3943f422014-11-14 05:09:55 +0400542 * @member: the name of the list_head within the struct.
Randy Dunlapfe96e572006-06-25 05:47:42 -0700543 *
544 * Iterate over list of given type, continuing after current point,
545 * safe against removal of list entry.
Arnaldo Carvalho de Melo74459dc2005-08-09 20:15:51 -0700546 */
547#define list_for_each_entry_safe_continue(pos, n, head, member) \
Oleg Nesterov8120e2e2013-11-12 15:10:02 -0800548 for (pos = list_next_entry(pos, member), \
549 n = list_next_entry(pos, member); \
Arnaldo Carvalho de Melo74459dc2005-08-09 20:15:51 -0700550 &pos->member != (head); \
Oleg Nesterov8120e2e2013-11-12 15:10:02 -0800551 pos = n, n = list_next_entry(n, member))
Arnaldo Carvalho de Melo74459dc2005-08-09 20:15:51 -0700552
553/**
Ben Hutchings9a86e2b2010-03-05 13:43:17 -0800554 * list_for_each_entry_safe_from - iterate over list from current point safe against removal
Randy Dunlap8e3a67a2006-06-25 05:47:43 -0700555 * @pos: the type * to use as a loop cursor.
Arnaldo Carvalho de Melod8dcffe2006-03-20 17:18:05 -0800556 * @n: another type * to use as temporary storage
557 * @head: the head for your list.
Andrey Utkin3943f422014-11-14 05:09:55 +0400558 * @member: the name of the list_head within the struct.
Randy Dunlapfe96e572006-06-25 05:47:42 -0700559 *
560 * Iterate over list of given type from current point, safe against
561 * removal of list entry.
Arnaldo Carvalho de Melod8dcffe2006-03-20 17:18:05 -0800562 */
563#define list_for_each_entry_safe_from(pos, n, head, member) \
Oleg Nesterov8120e2e2013-11-12 15:10:02 -0800564 for (n = list_next_entry(pos, member); \
Arnaldo Carvalho de Melod8dcffe2006-03-20 17:18:05 -0800565 &pos->member != (head); \
Oleg Nesterov8120e2e2013-11-12 15:10:02 -0800566 pos = n, n = list_next_entry(n, member))
Arnaldo Carvalho de Melod8dcffe2006-03-20 17:18:05 -0800567
568/**
Ben Hutchings9a86e2b2010-03-05 13:43:17 -0800569 * list_for_each_entry_safe_reverse - iterate backwards over list safe against removal
Randy Dunlap8e3a67a2006-06-25 05:47:43 -0700570 * @pos: the type * to use as a loop cursor.
David Howells0ad42352006-01-09 20:51:31 -0800571 * @n: another type * to use as temporary storage
572 * @head: the head for your list.
Andrey Utkin3943f422014-11-14 05:09:55 +0400573 * @member: the name of the list_head within the struct.
Randy Dunlapfe96e572006-06-25 05:47:42 -0700574 *
575 * Iterate backwards over list of given type, safe against removal
576 * of list entry.
David Howells0ad42352006-01-09 20:51:31 -0800577 */
578#define list_for_each_entry_safe_reverse(pos, n, head, member) \
Oleg Nesterov93be3c22013-11-12 15:10:03 -0800579 for (pos = list_last_entry(head, typeof(*pos), member), \
Oleg Nesterov8120e2e2013-11-12 15:10:02 -0800580 n = list_prev_entry(pos, member); \
David Howells0ad42352006-01-09 20:51:31 -0800581 &pos->member != (head); \
Oleg Nesterov8120e2e2013-11-12 15:10:02 -0800582 pos = n, n = list_prev_entry(n, member))
David Howells0ad42352006-01-09 20:51:31 -0800583
npiggin@suse.de57439f82010-06-24 13:02:14 +1000584/**
585 * list_safe_reset_next - reset a stale list_for_each_entry_safe loop
586 * @pos: the loop cursor used in the list_for_each_entry_safe loop
587 * @n: temporary storage used in list_for_each_entry_safe
Andrey Utkin3943f422014-11-14 05:09:55 +0400588 * @member: the name of the list_head within the struct.
npiggin@suse.de57439f82010-06-24 13:02:14 +1000589 *
590 * list_safe_reset_next is not safe to use in general if the list may be
591 * modified concurrently (eg. the lock is dropped in the loop body). An
592 * exception to this is if the cursor element (pos) is pinned in the list,
593 * and list_safe_reset_next is called after re-taking the lock and before
594 * completing the current iteration of the loop body.
595 */
596#define list_safe_reset_next(pos, n, member) \
Oleg Nesterov8120e2e2013-11-12 15:10:02 -0800597 n = list_next_entry(pos, member)
npiggin@suse.de57439f82010-06-24 13:02:14 +1000598
Linus Torvalds1da177e2005-04-16 15:20:36 -0700599/*
600 * Double linked lists with a single pointer list head.
601 * Mostly useful for hash tables where the two pointer list head is
602 * too wasteful.
603 * You lose the ability to access the tail in O(1).
604 */
605
Linus Torvalds1da177e2005-04-16 15:20:36 -0700606#define HLIST_HEAD_INIT { .first = NULL }
607#define HLIST_HEAD(name) struct hlist_head name = { .first = NULL }
608#define INIT_HLIST_HEAD(ptr) ((ptr)->first = NULL)
Zach Brown490d6ab2006-02-03 03:03:56 -0800609static inline void INIT_HLIST_NODE(struct hlist_node *h)
610{
611 h->next = NULL;
612 h->pprev = NULL;
613}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700614
615static inline int hlist_unhashed(const struct hlist_node *h)
616{
617 return !h->pprev;
618}
619
620static inline int hlist_empty(const struct hlist_head *h)
621{
Paul E. McKenney1658d352015-09-20 17:03:16 -0700622 return !READ_ONCE(h->first);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700623}
624
625static inline void __hlist_del(struct hlist_node *n)
626{
627 struct hlist_node *next = n->next;
628 struct hlist_node **pprev = n->pprev;
Paul E. McKenney7f5f8732015-09-18 08:45:22 -0700629
630 WRITE_ONCE(*pprev, next);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700631 if (next)
632 next->pprev = pprev;
633}
634
635static inline void hlist_del(struct hlist_node *n)
636{
637 __hlist_del(n);
638 n->next = LIST_POISON1;
639 n->pprev = LIST_POISON2;
640}
641
Linus Torvalds1da177e2005-04-16 15:20:36 -0700642static inline void hlist_del_init(struct hlist_node *n)
643{
Akinobu Mitada753be2006-04-28 15:21:23 -0700644 if (!hlist_unhashed(n)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700645 __hlist_del(n);
646 INIT_HLIST_NODE(n);
647 }
648}
649
650static inline void hlist_add_head(struct hlist_node *n, struct hlist_head *h)
651{
652 struct hlist_node *first = h->first;
653 n->next = first;
654 if (first)
655 first->pprev = &n->next;
Paul E. McKenney1c97be62015-09-20 22:02:17 -0700656 WRITE_ONCE(h->first, n);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700657 n->pprev = &h->first;
658}
659
Linus Torvalds1da177e2005-04-16 15:20:36 -0700660/* next must be != NULL */
661static inline void hlist_add_before(struct hlist_node *n,
662 struct hlist_node *next)
663{
664 n->pprev = next->pprev;
665 n->next = next;
666 next->pprev = &n->next;
Paul E. McKenney1c97be62015-09-20 22:02:17 -0700667 WRITE_ONCE(*(n->pprev), n);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700668}
669
Ken Helias1d023282014-08-06 16:09:16 -0700670static inline void hlist_add_behind(struct hlist_node *n,
671 struct hlist_node *prev)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700672{
Ken Heliasbc18dd32014-08-06 16:09:14 -0700673 n->next = prev->next;
Paul E. McKenney1c97be62015-09-20 22:02:17 -0700674 WRITE_ONCE(prev->next, n);
Ken Heliasbc18dd32014-08-06 16:09:14 -0700675 n->pprev = &prev->next;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700676
Ken Heliasbc18dd32014-08-06 16:09:14 -0700677 if (n->next)
678 n->next->pprev = &n->next;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700679}
680
Al Viro756acc22010-10-23 15:23:40 -0400681/* after that we'll appear to be on some hlist and hlist_del will work */
682static inline void hlist_add_fake(struct hlist_node *n)
683{
684 n->pprev = &n->next;
685}
686
Josef Bacikcbedaac2015-03-12 08:19:11 -0400687static inline bool hlist_fake(struct hlist_node *h)
688{
689 return h->pprev == &h->next;
690}
691
Vegard Nossum673d62cc2008-08-31 23:39:21 +0200692/*
693 * Move a list from one list head to another. Fixup the pprev
694 * reference of the first entry if it exists.
695 */
696static inline void hlist_move_list(struct hlist_head *old,
697 struct hlist_head *new)
698{
699 new->first = old->first;
700 if (new->first)
701 new->first->pprev = &new->first;
702 old->first = NULL;
703}
704
Linus Torvalds1da177e2005-04-16 15:20:36 -0700705#define hlist_entry(ptr, type, member) container_of(ptr,type,member)
706
707#define hlist_for_each(pos, head) \
Linus Torvalds75d65a42011-05-19 13:50:07 -0700708 for (pos = (head)->first; pos ; pos = pos->next)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700709
710#define hlist_for_each_safe(pos, n, head) \
711 for (pos = (head)->first; pos && ({ n = pos->next; 1; }); \
712 pos = n)
713
Sasha Levinb67bfe02013-02-27 17:06:00 -0800714#define hlist_entry_safe(ptr, type, member) \
Paul E. McKenneyf65846a2013-03-09 07:38:41 -0800715 ({ typeof(ptr) ____ptr = (ptr); \
716 ____ptr ? hlist_entry(____ptr, type, member) : NULL; \
717 })
Sasha Levinb67bfe02013-02-27 17:06:00 -0800718
Linus Torvalds1da177e2005-04-16 15:20:36 -0700719/**
720 * hlist_for_each_entry - iterate over list of given type
Sasha Levinb67bfe02013-02-27 17:06:00 -0800721 * @pos: the type * to use as a loop cursor.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700722 * @head: the head for your list.
723 * @member: the name of the hlist_node within the struct.
724 */
Sasha Levinb67bfe02013-02-27 17:06:00 -0800725#define hlist_for_each_entry(pos, head, member) \
726 for (pos = hlist_entry_safe((head)->first, typeof(*(pos)), member);\
727 pos; \
728 pos = hlist_entry_safe((pos)->member.next, typeof(*(pos)), member))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700729
730/**
Randy Dunlapfe96e572006-06-25 05:47:42 -0700731 * hlist_for_each_entry_continue - iterate over a hlist continuing after current point
Sasha Levinb67bfe02013-02-27 17:06:00 -0800732 * @pos: the type * to use as a loop cursor.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700733 * @member: the name of the hlist_node within the struct.
734 */
Sasha Levinb67bfe02013-02-27 17:06:00 -0800735#define hlist_for_each_entry_continue(pos, member) \
736 for (pos = hlist_entry_safe((pos)->member.next, typeof(*(pos)), member);\
737 pos; \
738 pos = hlist_entry_safe((pos)->member.next, typeof(*(pos)), member))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700739
740/**
Randy Dunlapfe96e572006-06-25 05:47:42 -0700741 * hlist_for_each_entry_from - iterate over a hlist continuing from current point
Sasha Levinb67bfe02013-02-27 17:06:00 -0800742 * @pos: the type * to use as a loop cursor.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700743 * @member: the name of the hlist_node within the struct.
744 */
Sasha Levinb67bfe02013-02-27 17:06:00 -0800745#define hlist_for_each_entry_from(pos, member) \
746 for (; pos; \
747 pos = hlist_entry_safe((pos)->member.next, typeof(*(pos)), member))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700748
749/**
750 * hlist_for_each_entry_safe - iterate over list of given type safe against removal of list entry
Sasha Levinb67bfe02013-02-27 17:06:00 -0800751 * @pos: the type * to use as a loop cursor.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700752 * @n: another &struct hlist_node to use as temporary storage
753 * @head: the head for your list.
754 * @member: the name of the hlist_node within the struct.
755 */
Sasha Levinb67bfe02013-02-27 17:06:00 -0800756#define hlist_for_each_entry_safe(pos, n, head, member) \
757 for (pos = hlist_entry_safe((head)->first, typeof(*pos), member);\
758 pos && ({ n = pos->member.next; 1; }); \
759 pos = hlist_entry_safe(n, typeof(*pos), member))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700760
Linus Torvalds1da177e2005-04-16 15:20:36 -0700761#endif