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Linus Torvalds1da177e2005-04-16 15:20:36 -07001#ifndef _LINUX_LIST_H
2#define _LINUX_LIST_H
3
Linus Torvalds1da177e2005-04-16 15:20:36 -07004#include <linux/stddef.h>
Randy Dunlapc9cf5522006-06-27 02:53:52 -07005#include <linux/poison.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -07006#include <linux/prefetch.h>
7#include <asm/system.h>
8
9/*
Linus Torvalds1da177e2005-04-16 15:20:36 -070010 * Simple doubly linked list implementation.
11 *
12 * Some of the internal functions ("__xxx") are useful when
13 * manipulating whole lists rather than single entries, as
14 * sometimes we already know the next/prev entries and we can
15 * generate better code by using them directly rather than
16 * using the generic single-entry routines.
17 */
18
19struct list_head {
20 struct list_head *next, *prev;
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
Zach Brown490d6ab2006-02-03 03:03:56 -080028static inline void INIT_LIST_HEAD(struct list_head *list)
29{
30 list->next = list;
31 list->prev = list;
32}
Linus Torvalds1da177e2005-04-16 15:20:36 -070033
34/*
35 * Insert a new entry between two known consecutive entries.
36 *
37 * This is only for internal list manipulation where we know
38 * the prev/next entries already!
39 */
Dave Jones199a9af2006-09-29 01:59:00 -070040#ifndef CONFIG_DEBUG_LIST
Linus Torvalds1da177e2005-04-16 15:20:36 -070041static inline void __list_add(struct list_head *new,
42 struct list_head *prev,
43 struct list_head *next)
44{
45 next->prev = new;
46 new->next = next;
47 new->prev = prev;
48 prev->next = new;
49}
Dave Jones199a9af2006-09-29 01:59:00 -070050#else
51extern void __list_add(struct list_head *new,
52 struct list_head *prev,
53 struct list_head *next);
54#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -070055
56/**
57 * list_add - add a new entry
58 * @new: new entry to be added
59 * @head: list head to add it after
60 *
61 * Insert a new entry after the specified head.
62 * This is good for implementing stacks.
63 */
64static inline void list_add(struct list_head *new, struct list_head *head)
65{
66 __list_add(new, head, head->next);
67}
Dave Jones199a9af2006-09-29 01:59:00 -070068
Linus Torvalds1da177e2005-04-16 15:20:36 -070069
70/**
71 * list_add_tail - add a new entry
72 * @new: new entry to be added
73 * @head: list head to add it before
74 *
75 * Insert a new entry before the specified head.
76 * This is useful for implementing queues.
77 */
78static inline void list_add_tail(struct list_head *new, struct list_head *head)
79{
80 __list_add(new, head->prev, head);
81}
82
83/*
Linus Torvalds1da177e2005-04-16 15:20:36 -070084 * Delete a list entry by making the prev/next entries
85 * point to each other.
86 *
87 * This is only for internal list manipulation where we know
88 * the prev/next entries already!
89 */
90static inline void __list_del(struct list_head * prev, struct list_head * next)
91{
92 next->prev = prev;
93 prev->next = next;
94}
95
96/**
97 * list_del - deletes entry from list.
98 * @entry: the element to delete from the list.
Robert P. J. Day72fd4a32007-02-10 01:45:59 -080099 * Note: list_empty() on entry does not return true after this, the entry is
Linus Torvalds1da177e2005-04-16 15:20:36 -0700100 * in an undefined state.
101 */
Dave Jones199a9af2006-09-29 01:59:00 -0700102#ifndef CONFIG_DEBUG_LIST
Linus Torvalds1da177e2005-04-16 15:20:36 -0700103static inline void list_del(struct list_head *entry)
104{
105 __list_del(entry->prev, entry->next);
106 entry->next = LIST_POISON1;
107 entry->prev = LIST_POISON2;
108}
Dave Jones199a9af2006-09-29 01:59:00 -0700109#else
110extern void list_del(struct list_head *entry);
111#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -0700112
113/**
Oleg Nesterov54e73772006-06-23 02:05:54 -0700114 * list_replace - replace old entry by new one
115 * @old : the element to be replaced
116 * @new : the new element to insert
Robert P. J. Day72fd4a32007-02-10 01:45:59 -0800117 *
118 * If @old was empty, it will be overwritten.
Oleg Nesterov54e73772006-06-23 02:05:54 -0700119 */
120static inline void list_replace(struct list_head *old,
121 struct list_head *new)
122{
123 new->next = old->next;
124 new->next->prev = new;
125 new->prev = old->prev;
126 new->prev->next = new;
127}
128
129static inline void list_replace_init(struct list_head *old,
130 struct list_head *new)
131{
132 list_replace(old, new);
133 INIT_LIST_HEAD(old);
134}
135
Robert P. J. Day45f8bde2007-01-26 00:57:09 -0800136/**
Linus Torvalds1da177e2005-04-16 15:20:36 -0700137 * list_del_init - deletes entry from list and reinitialize it.
138 * @entry: the element to delete from the list.
139 */
140static inline void list_del_init(struct list_head *entry)
141{
142 __list_del(entry->prev, entry->next);
143 INIT_LIST_HEAD(entry);
144}
145
146/**
147 * list_move - delete from one list and add as another's head
148 * @list: the entry to move
149 * @head: the head that will precede our entry
150 */
151static inline void list_move(struct list_head *list, struct list_head *head)
152{
Daniel Walker78db2ad2007-05-12 16:28:35 -0700153 __list_del(list->prev, list->next);
154 list_add(list, head);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700155}
156
157/**
158 * list_move_tail - delete from one list and add as another's tail
159 * @list: the entry to move
160 * @head: the head that will follow our entry
161 */
162static inline void list_move_tail(struct list_head *list,
163 struct list_head *head)
164{
Daniel Walker78db2ad2007-05-12 16:28:35 -0700165 __list_del(list->prev, list->next);
166 list_add_tail(list, head);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700167}
168
169/**
Shailabh Nagare8f4d972006-07-14 00:24:35 -0700170 * list_is_last - tests whether @list is the last entry in list @head
171 * @list: the entry to test
172 * @head: the head of the list
173 */
174static inline int list_is_last(const struct list_head *list,
175 const struct list_head *head)
176{
177 return list->next == head;
178}
179
180/**
Linus Torvalds1da177e2005-04-16 15:20:36 -0700181 * list_empty - tests whether a list is empty
182 * @head: the list to test.
183 */
184static inline int list_empty(const struct list_head *head)
185{
186 return head->next == head;
187}
188
189/**
Randy Dunlapfe96e572006-06-25 05:47:42 -0700190 * list_empty_careful - tests whether a list is empty and not being modified
191 * @head: the list to test
192 *
193 * Description:
194 * tests whether a list is empty _and_ checks that no other CPU might be
195 * in the process of modifying either member (next or prev)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700196 *
197 * NOTE: using list_empty_careful() without synchronization
198 * can only be safe if the only activity that can happen
199 * to the list entry is list_del_init(). Eg. it cannot be used
200 * if another CPU could re-list_add() it.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700201 */
202static inline int list_empty_careful(const struct list_head *head)
203{
204 struct list_head *next = head->next;
205 return (next == head) && (next == head->prev);
206}
207
Masami Hiramatsu99602572008-04-28 02:14:27 -0700208/**
Frederic Weisbecker5908cdc2010-01-09 20:53:14 +0100209 * list_rotate_left - rotate the list to the left
210 * @head: the head of the list
211 */
212static inline void list_rotate_left(struct list_head *head)
213{
214 struct list_head *first;
215
216 if (!list_empty(head)) {
217 first = head->next;
218 list_move_tail(first, head);
219 }
220}
221
222/**
Masami Hiramatsu99602572008-04-28 02:14:27 -0700223 * list_is_singular - tests whether a list has just one entry.
224 * @head: the list to test.
225 */
226static inline int list_is_singular(const struct list_head *head)
227{
228 return !list_empty(head) && (head->next == head->prev);
229}
230
Luis R. Rodriguez00e8a4d2008-08-06 13:28:54 -0700231static inline void __list_cut_position(struct list_head *list,
232 struct list_head *head, struct list_head *entry)
233{
234 struct list_head *new_first = entry->next;
235 list->next = head->next;
236 list->next->prev = list;
237 list->prev = entry;
238 entry->next = list;
239 head->next = new_first;
240 new_first->prev = head;
241}
242
243/**
244 * list_cut_position - cut a list into two
245 * @list: a new list to add all removed entries
246 * @head: a list with entries
247 * @entry: an entry within head, could be the head itself
248 * and if so we won't cut the list
249 *
250 * This helper moves the initial part of @head, up to and
251 * including @entry, from @head to @list. You should
252 * pass on @entry an element you know is on @head. @list
253 * should be an empty list or a list you do not care about
254 * losing its data.
255 *
256 */
257static inline void list_cut_position(struct list_head *list,
258 struct list_head *head, struct list_head *entry)
259{
260 if (list_empty(head))
261 return;
262 if (list_is_singular(head) &&
263 (head->next != entry && head != entry))
264 return;
265 if (entry == head)
266 INIT_LIST_HEAD(list);
267 else
268 __list_cut_position(list, head, entry);
269}
270
Robert P. J. Day95d8c362008-04-29 00:59:29 -0700271static inline void __list_splice(const struct list_head *list,
Luis R. Rodriguez7d283ae2008-08-06 15:21:26 -0700272 struct list_head *prev,
273 struct list_head *next)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700274{
275 struct list_head *first = list->next;
276 struct list_head *last = list->prev;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700277
Luis R. Rodriguez7d283ae2008-08-06 15:21:26 -0700278 first->prev = prev;
279 prev->next = first;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700280
Luis R. Rodriguez7d283ae2008-08-06 15:21:26 -0700281 last->next = next;
282 next->prev = last;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700283}
284
285/**
Luis R. Rodriguez7d283ae2008-08-06 15:21:26 -0700286 * list_splice - join two lists, this is designed for stacks
Linus Torvalds1da177e2005-04-16 15:20:36 -0700287 * @list: the new list to add.
288 * @head: the place to add it in the first list.
289 */
Robert P. J. Day95d8c362008-04-29 00:59:29 -0700290static inline void list_splice(const struct list_head *list,
291 struct list_head *head)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700292{
293 if (!list_empty(list))
Luis R. Rodriguez7d283ae2008-08-06 15:21:26 -0700294 __list_splice(list, head, head->next);
295}
296
297/**
298 * list_splice_tail - join two lists, each list being a queue
299 * @list: the new list to add.
300 * @head: the place to add it in the first list.
301 */
302static inline void list_splice_tail(struct list_head *list,
303 struct list_head *head)
304{
305 if (!list_empty(list))
306 __list_splice(list, head->prev, head);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700307}
308
309/**
310 * list_splice_init - join two lists and reinitialise the emptied list.
311 * @list: the new list to add.
312 * @head: the place to add it in the first list.
313 *
314 * The list at @list is reinitialised
315 */
316static inline void list_splice_init(struct list_head *list,
317 struct list_head *head)
318{
319 if (!list_empty(list)) {
Luis R. Rodriguez7d283ae2008-08-06 15:21:26 -0700320 __list_splice(list, head, head->next);
321 INIT_LIST_HEAD(list);
322 }
323}
324
325/**
Randy Dunlap6724cce2008-08-08 13:56:20 -0700326 * list_splice_tail_init - join two lists and reinitialise the emptied list
Luis R. Rodriguez7d283ae2008-08-06 15:21:26 -0700327 * @list: the new list to add.
328 * @head: the place to add it in the first list.
329 *
Randy Dunlap6724cce2008-08-08 13:56:20 -0700330 * Each of the lists is a queue.
Luis R. Rodriguez7d283ae2008-08-06 15:21:26 -0700331 * The list at @list is reinitialised
332 */
333static inline void list_splice_tail_init(struct list_head *list,
334 struct list_head *head)
335{
336 if (!list_empty(list)) {
337 __list_splice(list, head->prev, head);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700338 INIT_LIST_HEAD(list);
339 }
340}
341
342/**
343 * list_entry - get the struct for this entry
344 * @ptr: the &struct list_head pointer.
345 * @type: the type of the struct this is embedded in.
346 * @member: the name of the list_struct within the struct.
347 */
348#define list_entry(ptr, type, member) \
349 container_of(ptr, type, member)
350
351/**
Pavel Emelianovb5e61812007-05-08 00:30:19 -0700352 * list_first_entry - get the first element from a list
353 * @ptr: the list head to take the element from.
354 * @type: the type of the struct this is embedded in.
355 * @member: the name of the list_struct within the struct.
356 *
357 * Note, that list is expected to be not empty.
358 */
359#define list_first_entry(ptr, type, member) \
360 list_entry((ptr)->next, type, member)
361
362/**
Linus Torvalds1da177e2005-04-16 15:20:36 -0700363 * list_for_each - iterate over a list
Randy Dunlap8e3a67a2006-06-25 05:47:43 -0700364 * @pos: the &struct list_head to use as a loop cursor.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700365 * @head: the head for your list.
366 */
367#define list_for_each(pos, head) \
368 for (pos = (head)->next; prefetch(pos->next), pos != (head); \
369 pos = pos->next)
370
371/**
372 * __list_for_each - iterate over a list
Randy Dunlap8e3a67a2006-06-25 05:47:43 -0700373 * @pos: the &struct list_head to use as a loop cursor.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700374 * @head: the head for your list.
375 *
376 * This variant differs from list_for_each() in that it's the
377 * simplest possible list iteration code, no prefetching is done.
378 * Use this for code that knows the list to be very short (empty
379 * or 1 entry) most of the time.
380 */
381#define __list_for_each(pos, head) \
382 for (pos = (head)->next; pos != (head); pos = pos->next)
383
384/**
385 * list_for_each_prev - iterate over a list backwards
Randy Dunlap8e3a67a2006-06-25 05:47:43 -0700386 * @pos: the &struct list_head to use as a loop cursor.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700387 * @head: the head for your list.
388 */
389#define list_for_each_prev(pos, head) \
390 for (pos = (head)->prev; prefetch(pos->prev), pos != (head); \
391 pos = pos->prev)
392
393/**
Randy Dunlapfe96e572006-06-25 05:47:42 -0700394 * list_for_each_safe - iterate over a list safe against removal of list entry
Randy Dunlap8e3a67a2006-06-25 05:47:43 -0700395 * @pos: the &struct list_head to use as a loop cursor.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700396 * @n: another &struct list_head to use as temporary storage
397 * @head: the head for your list.
398 */
399#define list_for_each_safe(pos, n, head) \
400 for (pos = (head)->next, n = pos->next; pos != (head); \
401 pos = n, n = pos->next)
402
403/**
Randy Dunlap8f731f72007-10-18 23:39:28 -0700404 * list_for_each_prev_safe - iterate over a list backwards safe against removal of list entry
Denis V. Lunev37c42522007-10-16 23:29:53 -0700405 * @pos: the &struct list_head to use as a loop cursor.
406 * @n: another &struct list_head to use as temporary storage
407 * @head: the head for your list.
408 */
409#define list_for_each_prev_safe(pos, n, head) \
410 for (pos = (head)->prev, n = pos->prev; \
411 prefetch(pos->prev), pos != (head); \
412 pos = n, n = pos->prev)
413
414/**
Linus Torvalds1da177e2005-04-16 15:20:36 -0700415 * list_for_each_entry - iterate over list of given type
Randy Dunlap8e3a67a2006-06-25 05:47:43 -0700416 * @pos: the type * to use as a loop cursor.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700417 * @head: the head for your list.
418 * @member: the name of the list_struct within the struct.
419 */
420#define list_for_each_entry(pos, head, member) \
421 for (pos = list_entry((head)->next, typeof(*pos), member); \
422 prefetch(pos->member.next), &pos->member != (head); \
423 pos = list_entry(pos->member.next, typeof(*pos), member))
424
425/**
426 * list_for_each_entry_reverse - iterate backwards over list of given type.
Randy Dunlap8e3a67a2006-06-25 05:47:43 -0700427 * @pos: the type * to use as a loop cursor.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700428 * @head: the head for your list.
429 * @member: the name of the list_struct within the struct.
430 */
431#define list_for_each_entry_reverse(pos, head, member) \
432 for (pos = list_entry((head)->prev, typeof(*pos), member); \
433 prefetch(pos->member.prev), &pos->member != (head); \
434 pos = list_entry(pos->member.prev, typeof(*pos), member))
435
436/**
Robert P. J. Day72fd4a32007-02-10 01:45:59 -0800437 * list_prepare_entry - prepare a pos entry for use in list_for_each_entry_continue()
Linus Torvalds1da177e2005-04-16 15:20:36 -0700438 * @pos: the type * to use as a start point
439 * @head: the head of the list
440 * @member: the name of the list_struct within the struct.
Randy Dunlapfe96e572006-06-25 05:47:42 -0700441 *
Robert P. J. Day72fd4a32007-02-10 01:45:59 -0800442 * Prepares a pos entry for use as a start point in list_for_each_entry_continue().
Linus Torvalds1da177e2005-04-16 15:20:36 -0700443 */
444#define list_prepare_entry(pos, head, member) \
445 ((pos) ? : list_entry(head, typeof(*pos), member))
446
447/**
Randy Dunlapfe96e572006-06-25 05:47:42 -0700448 * list_for_each_entry_continue - continue iteration over list of given type
Randy Dunlap8e3a67a2006-06-25 05:47:43 -0700449 * @pos: the type * to use as a loop cursor.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700450 * @head: the head for your list.
451 * @member: the name of the list_struct within the struct.
Randy Dunlapfe96e572006-06-25 05:47:42 -0700452 *
453 * Continue to iterate over list of given type, continuing after
454 * the current position.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700455 */
456#define list_for_each_entry_continue(pos, head, member) \
457 for (pos = list_entry(pos->member.next, typeof(*pos), member); \
458 prefetch(pos->member.next), &pos->member != (head); \
459 pos = list_entry(pos->member.next, typeof(*pos), member))
460
461/**
Pavel Emelyanov768f35912007-09-18 13:20:41 -0700462 * list_for_each_entry_continue_reverse - iterate backwards from the given point
463 * @pos: the type * to use as a loop cursor.
464 * @head: the head for your list.
465 * @member: the name of the list_struct within the struct.
466 *
467 * Start to iterate over list of given type backwards, continuing after
468 * the current position.
469 */
470#define list_for_each_entry_continue_reverse(pos, head, member) \
471 for (pos = list_entry(pos->member.prev, typeof(*pos), member); \
472 prefetch(pos->member.prev), &pos->member != (head); \
473 pos = list_entry(pos->member.prev, typeof(*pos), member))
474
475/**
Randy Dunlapfe96e572006-06-25 05:47:42 -0700476 * list_for_each_entry_from - iterate over list of given type from the current point
Randy Dunlap8e3a67a2006-06-25 05:47:43 -0700477 * @pos: the type * to use as a loop cursor.
Arnaldo Carvalho de Meloe229c2f2006-03-20 17:19:17 -0800478 * @head: the head for your list.
479 * @member: the name of the list_struct within the struct.
Randy Dunlapfe96e572006-06-25 05:47:42 -0700480 *
481 * Iterate over list of given type, continuing from current position.
Arnaldo Carvalho de Meloe229c2f2006-03-20 17:19:17 -0800482 */
483#define list_for_each_entry_from(pos, head, member) \
484 for (; prefetch(pos->member.next), &pos->member != (head); \
485 pos = list_entry(pos->member.next, typeof(*pos), member))
486
487/**
Linus Torvalds1da177e2005-04-16 15:20:36 -0700488 * list_for_each_entry_safe - iterate over list of given type safe against removal of list entry
Randy Dunlap8e3a67a2006-06-25 05:47:43 -0700489 * @pos: the type * to use as a loop cursor.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700490 * @n: another type * to use as temporary storage
491 * @head: the head for your list.
492 * @member: the name of the list_struct within the struct.
493 */
494#define list_for_each_entry_safe(pos, n, head, member) \
495 for (pos = list_entry((head)->next, typeof(*pos), member), \
496 n = list_entry(pos->member.next, typeof(*pos), member); \
497 &pos->member != (head); \
498 pos = n, n = list_entry(n->member.next, typeof(*n), member))
499
500/**
Ben Hutchings9a86e2b2010-03-05 13:43:17 -0800501 * list_for_each_entry_safe_continue - continue list iteration safe against removal
Randy Dunlap8e3a67a2006-06-25 05:47:43 -0700502 * @pos: the type * to use as a loop cursor.
Arnaldo Carvalho de Melo74459dc2005-08-09 20:15:51 -0700503 * @n: another type * to use as temporary storage
504 * @head: the head for your list.
505 * @member: the name of the list_struct within the struct.
Randy Dunlapfe96e572006-06-25 05:47:42 -0700506 *
507 * Iterate over list of given type, continuing after current point,
508 * safe against removal of list entry.
Arnaldo Carvalho de Melo74459dc2005-08-09 20:15:51 -0700509 */
510#define list_for_each_entry_safe_continue(pos, n, head, member) \
Arnaldo Carvalho de Melo8c60f3f2005-08-10 12:59:38 -0300511 for (pos = list_entry(pos->member.next, typeof(*pos), member), \
512 n = list_entry(pos->member.next, typeof(*pos), member); \
Arnaldo Carvalho de Melo74459dc2005-08-09 20:15:51 -0700513 &pos->member != (head); \
514 pos = n, n = list_entry(n->member.next, typeof(*n), member))
515
516/**
Ben Hutchings9a86e2b2010-03-05 13:43:17 -0800517 * list_for_each_entry_safe_from - iterate over list from current point safe against removal
Randy Dunlap8e3a67a2006-06-25 05:47:43 -0700518 * @pos: the type * to use as a loop cursor.
Arnaldo Carvalho de Melod8dcffe2006-03-20 17:18:05 -0800519 * @n: another type * to use as temporary storage
520 * @head: the head for your list.
521 * @member: the name of the list_struct within the struct.
Randy Dunlapfe96e572006-06-25 05:47:42 -0700522 *
523 * Iterate over list of given type from current point, safe against
524 * removal of list entry.
Arnaldo Carvalho de Melod8dcffe2006-03-20 17:18:05 -0800525 */
526#define list_for_each_entry_safe_from(pos, n, head, member) \
527 for (n = list_entry(pos->member.next, typeof(*pos), member); \
528 &pos->member != (head); \
529 pos = n, n = list_entry(n->member.next, typeof(*n), member))
530
531/**
Ben Hutchings9a86e2b2010-03-05 13:43:17 -0800532 * list_for_each_entry_safe_reverse - iterate backwards over list safe against removal
Randy Dunlap8e3a67a2006-06-25 05:47:43 -0700533 * @pos: the type * to use as a loop cursor.
David Howells0ad42352006-01-09 20:51:31 -0800534 * @n: another type * to use as temporary storage
535 * @head: the head for your list.
536 * @member: the name of the list_struct within the struct.
Randy Dunlapfe96e572006-06-25 05:47:42 -0700537 *
538 * Iterate backwards over list of given type, safe against removal
539 * of list entry.
David Howells0ad42352006-01-09 20:51:31 -0800540 */
541#define list_for_each_entry_safe_reverse(pos, n, head, member) \
542 for (pos = list_entry((head)->prev, typeof(*pos), member), \
543 n = list_entry(pos->member.prev, typeof(*pos), member); \
544 &pos->member != (head); \
545 pos = n, n = list_entry(n->member.prev, typeof(*n), member))
546
npiggin@suse.de57439f82010-06-24 13:02:14 +1000547/**
548 * list_safe_reset_next - reset a stale list_for_each_entry_safe loop
549 * @pos: the loop cursor used in the list_for_each_entry_safe loop
550 * @n: temporary storage used in list_for_each_entry_safe
551 * @member: the name of the list_struct within the struct.
552 *
553 * list_safe_reset_next is not safe to use in general if the list may be
554 * modified concurrently (eg. the lock is dropped in the loop body). An
555 * exception to this is if the cursor element (pos) is pinned in the list,
556 * and list_safe_reset_next is called after re-taking the lock and before
557 * completing the current iteration of the loop body.
558 */
559#define list_safe_reset_next(pos, n, member) \
560 n = list_entry(pos->member.next, typeof(*pos), member)
561
Linus Torvalds1da177e2005-04-16 15:20:36 -0700562/*
563 * Double linked lists with a single pointer list head.
564 * Mostly useful for hash tables where the two pointer list head is
565 * too wasteful.
566 * You lose the ability to access the tail in O(1).
567 */
568
569struct hlist_head {
570 struct hlist_node *first;
571};
572
573struct hlist_node {
574 struct hlist_node *next, **pprev;
575};
576
577#define HLIST_HEAD_INIT { .first = NULL }
578#define HLIST_HEAD(name) struct hlist_head name = { .first = NULL }
579#define INIT_HLIST_HEAD(ptr) ((ptr)->first = NULL)
Zach Brown490d6ab2006-02-03 03:03:56 -0800580static inline void INIT_HLIST_NODE(struct hlist_node *h)
581{
582 h->next = NULL;
583 h->pprev = NULL;
584}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700585
586static inline int hlist_unhashed(const struct hlist_node *h)
587{
588 return !h->pprev;
589}
590
591static inline int hlist_empty(const struct hlist_head *h)
592{
593 return !h->first;
594}
595
596static inline void __hlist_del(struct hlist_node *n)
597{
598 struct hlist_node *next = n->next;
599 struct hlist_node **pprev = n->pprev;
600 *pprev = next;
601 if (next)
602 next->pprev = pprev;
603}
604
605static inline void hlist_del(struct hlist_node *n)
606{
607 __hlist_del(n);
608 n->next = LIST_POISON1;
609 n->pprev = LIST_POISON2;
610}
611
Linus Torvalds1da177e2005-04-16 15:20:36 -0700612static inline void hlist_del_init(struct hlist_node *n)
613{
Akinobu Mitada753be2006-04-28 15:21:23 -0700614 if (!hlist_unhashed(n)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700615 __hlist_del(n);
616 INIT_HLIST_NODE(n);
617 }
618}
619
620static inline void hlist_add_head(struct hlist_node *n, struct hlist_head *h)
621{
622 struct hlist_node *first = h->first;
623 n->next = first;
624 if (first)
625 first->pprev = &n->next;
626 h->first = n;
627 n->pprev = &h->first;
628}
629
Linus Torvalds1da177e2005-04-16 15:20:36 -0700630/* next must be != NULL */
631static inline void hlist_add_before(struct hlist_node *n,
632 struct hlist_node *next)
633{
634 n->pprev = next->pprev;
635 n->next = next;
636 next->pprev = &n->next;
637 *(n->pprev) = n;
638}
639
640static inline void hlist_add_after(struct hlist_node *n,
641 struct hlist_node *next)
642{
643 next->next = n->next;
644 n->next = next;
645 next->pprev = &n->next;
646
647 if(next->next)
648 next->next->pprev = &next->next;
649}
650
Vegard Nossum673d62cc2008-08-31 23:39:21 +0200651/*
652 * Move a list from one list head to another. Fixup the pprev
653 * reference of the first entry if it exists.
654 */
655static inline void hlist_move_list(struct hlist_head *old,
656 struct hlist_head *new)
657{
658 new->first = old->first;
659 if (new->first)
660 new->first->pprev = &new->first;
661 old->first = NULL;
662}
663
Linus Torvalds1da177e2005-04-16 15:20:36 -0700664#define hlist_entry(ptr, type, member) container_of(ptr,type,member)
665
666#define hlist_for_each(pos, head) \
667 for (pos = (head)->first; pos && ({ prefetch(pos->next); 1; }); \
668 pos = pos->next)
669
670#define hlist_for_each_safe(pos, n, head) \
671 for (pos = (head)->first; pos && ({ n = pos->next; 1; }); \
672 pos = n)
673
Linus Torvalds1da177e2005-04-16 15:20:36 -0700674/**
675 * hlist_for_each_entry - iterate over list of given type
Randy Dunlap8e3a67a2006-06-25 05:47:43 -0700676 * @tpos: the type * to use as a loop cursor.
677 * @pos: the &struct hlist_node to use as a loop cursor.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700678 * @head: the head for your list.
679 * @member: the name of the hlist_node within the struct.
680 */
681#define hlist_for_each_entry(tpos, pos, head, member) \
682 for (pos = (head)->first; \
683 pos && ({ prefetch(pos->next); 1;}) && \
684 ({ tpos = hlist_entry(pos, typeof(*tpos), member); 1;}); \
685 pos = pos->next)
686
687/**
Randy Dunlapfe96e572006-06-25 05:47:42 -0700688 * hlist_for_each_entry_continue - iterate over a hlist continuing after current point
Randy Dunlap8e3a67a2006-06-25 05:47:43 -0700689 * @tpos: the type * to use as a loop cursor.
690 * @pos: the &struct hlist_node to use as a loop cursor.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700691 * @member: the name of the hlist_node within the struct.
692 */
693#define hlist_for_each_entry_continue(tpos, pos, member) \
694 for (pos = (pos)->next; \
695 pos && ({ prefetch(pos->next); 1;}) && \
696 ({ tpos = hlist_entry(pos, typeof(*tpos), member); 1;}); \
697 pos = pos->next)
698
699/**
Randy Dunlapfe96e572006-06-25 05:47:42 -0700700 * hlist_for_each_entry_from - iterate over a hlist continuing from current point
Randy Dunlap8e3a67a2006-06-25 05:47:43 -0700701 * @tpos: the type * to use as a loop cursor.
702 * @pos: the &struct hlist_node to use as a loop cursor.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700703 * @member: the name of the hlist_node within the struct.
704 */
705#define hlist_for_each_entry_from(tpos, pos, member) \
706 for (; pos && ({ prefetch(pos->next); 1;}) && \
707 ({ tpos = hlist_entry(pos, typeof(*tpos), member); 1;}); \
708 pos = pos->next)
709
710/**
711 * hlist_for_each_entry_safe - iterate over list of given type safe against removal of list entry
Randy Dunlap8e3a67a2006-06-25 05:47:43 -0700712 * @tpos: the type * to use as a loop cursor.
713 * @pos: the &struct hlist_node to use as a loop cursor.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700714 * @n: another &struct hlist_node to use as temporary storage
715 * @head: the head for your list.
716 * @member: the name of the hlist_node within the struct.
717 */
718#define hlist_for_each_entry_safe(tpos, pos, n, head, member) \
719 for (pos = (head)->first; \
720 pos && ({ n = pos->next; 1; }) && \
721 ({ tpos = hlist_entry(pos, typeof(*tpos), member); 1;}); \
722 pos = n)
723
Linus Torvalds1da177e2005-04-16 15:20:36 -0700724#endif