4 #include <linux/stddef.h>
5 #include <linux/poison.h>
6 #include <linux/prefetch.h>
7 #include <asm/system.h>
10 * Simple doubly linked list implementation.
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.
20 struct list_head
*next
, *prev
;
23 #define LIST_HEAD_INIT(name) { &(name), &(name) }
25 #define LIST_HEAD(name) \
26 struct list_head name = LIST_HEAD_INIT(name)
28 static inline void INIT_LIST_HEAD(struct list_head
*list
)
35 * Insert a new entry between two known consecutive entries.
37 * This is only for internal list manipulation where we know
38 * the prev/next entries already!
40 #ifndef CONFIG_DEBUG_LIST
41 static inline void __list_add(struct list_head
*new,
42 struct list_head
*prev
,
43 struct list_head
*next
)
51 extern void __list_add(struct list_head
*new,
52 struct list_head
*prev
,
53 struct list_head
*next
);
57 * list_add - add a new entry
58 * @new: new entry to be added
59 * @head: list head to add it after
61 * Insert a new entry after the specified head.
62 * This is good for implementing stacks.
64 static inline void list_add(struct list_head
*new, struct list_head
*head
)
66 __list_add(new, head
, head
->next
);
71 * list_add_tail - add a new entry
72 * @new: new entry to be added
73 * @head: list head to add it before
75 * Insert a new entry before the specified head.
76 * This is useful for implementing queues.
78 static inline void list_add_tail(struct list_head
*new, struct list_head
*head
)
80 __list_add(new, head
->prev
, head
);
84 * Delete a list entry by making the prev/next entries
85 * point to each other.
87 * This is only for internal list manipulation where we know
88 * the prev/next entries already!
90 static inline void __list_del(struct list_head
* prev
, struct list_head
* next
)
97 * list_del - deletes entry from list.
98 * @entry: the element to delete from the list.
99 * Note: list_empty() on entry does not return true after this, the entry is
100 * in an undefined state.
102 #ifndef CONFIG_DEBUG_LIST
103 static inline void list_del(struct list_head
*entry
)
105 __list_del(entry
->prev
, entry
->next
);
106 entry
->next
= LIST_POISON1
;
107 entry
->prev
= LIST_POISON2
;
110 extern void list_del(struct list_head
*entry
);
114 * list_replace - replace old entry by new one
115 * @old : the element to be replaced
116 * @new : the new element to insert
118 * If @old was empty, it will be overwritten.
120 static inline void list_replace(struct list_head
*old
,
121 struct list_head
*new)
123 new->next
= old
->next
;
124 new->next
->prev
= new;
125 new->prev
= old
->prev
;
126 new->prev
->next
= new;
129 static inline void list_replace_init(struct list_head
*old
,
130 struct list_head
*new)
132 list_replace(old
, new);
137 * list_del_init - deletes entry from list and reinitialize it.
138 * @entry: the element to delete from the list.
140 static inline void list_del_init(struct list_head
*entry
)
142 __list_del(entry
->prev
, entry
->next
);
143 INIT_LIST_HEAD(entry
);
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
151 static inline void list_move(struct list_head
*list
, struct list_head
*head
)
153 __list_del(list
->prev
, list
->next
);
154 list_add(list
, head
);
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
162 static inline void list_move_tail(struct list_head
*list
,
163 struct list_head
*head
)
165 __list_del(list
->prev
, list
->next
);
166 list_add_tail(list
, head
);
170 * 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
174 static inline int list_is_last(const struct list_head
*list
,
175 const struct list_head
*head
)
177 return list
->next
== head
;
181 * list_empty - tests whether a list is empty
182 * @head: the list to test.
184 static inline int list_empty(const struct list_head
*head
)
186 return head
->next
== head
;
190 * list_empty_careful - tests whether a list is empty and not being modified
191 * @head: the list to test
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)
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.
202 static inline int list_empty_careful(const struct list_head
*head
)
204 struct list_head
*next
= head
->next
;
205 return (next
== head
) && (next
== head
->prev
);
209 * list_rotate_left - rotate the list to the left
210 * @head: the head of the list
212 static inline void list_rotate_left(struct list_head
*head
)
214 struct list_head
*first
;
216 if (!list_empty(head
)) {
218 list_move_tail(first
, head
);
223 * list_is_singular - tests whether a list has just one entry.
224 * @head: the list to test.
226 static inline int list_is_singular(const struct list_head
*head
)
228 return !list_empty(head
) && (head
->next
== head
->prev
);
231 static inline void __list_cut_position(struct list_head
*list
,
232 struct list_head
*head
, struct list_head
*entry
)
234 struct list_head
*new_first
= entry
->next
;
235 list
->next
= head
->next
;
236 list
->next
->prev
= list
;
239 head
->next
= new_first
;
240 new_first
->prev
= head
;
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
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
257 static inline void list_cut_position(struct list_head
*list
,
258 struct list_head
*head
, struct list_head
*entry
)
260 if (list_empty(head
))
262 if (list_is_singular(head
) &&
263 (head
->next
!= entry
&& head
!= entry
))
266 INIT_LIST_HEAD(list
);
268 __list_cut_position(list
, head
, entry
);
271 static inline void __list_splice(const struct list_head
*list
,
272 struct list_head
*prev
,
273 struct list_head
*next
)
275 struct list_head
*first
= list
->next
;
276 struct list_head
*last
= list
->prev
;
286 * list_splice - join two lists, this is designed for stacks
287 * @list: the new list to add.
288 * @head: the place to add it in the first list.
290 static inline void list_splice(const struct list_head
*list
,
291 struct list_head
*head
)
293 if (!list_empty(list
))
294 __list_splice(list
, head
, head
->next
);
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.
302 static inline void list_splice_tail(struct list_head
*list
,
303 struct list_head
*head
)
305 if (!list_empty(list
))
306 __list_splice(list
, head
->prev
, head
);
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.
314 * The list at @list is reinitialised
316 static inline void list_splice_init(struct list_head
*list
,
317 struct list_head
*head
)
319 if (!list_empty(list
)) {
320 __list_splice(list
, head
, head
->next
);
321 INIT_LIST_HEAD(list
);
326 * list_splice_tail_init - join two lists and reinitialise the emptied list
327 * @list: the new list to add.
328 * @head: the place to add it in the first list.
330 * Each of the lists is a queue.
331 * The list at @list is reinitialised
333 static inline void list_splice_tail_init(struct list_head
*list
,
334 struct list_head
*head
)
336 if (!list_empty(list
)) {
337 __list_splice(list
, head
->prev
, head
);
338 INIT_LIST_HEAD(list
);
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.
348 #define list_entry(ptr, type, member) \
349 container_of(ptr, type, member)
352 * 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.
357 * Note, that list is expected to be not empty.
359 #define list_first_entry(ptr, type, member) \
360 list_entry((ptr)->next, type, member)
363 * list_for_each - iterate over a list
364 * @pos: the &struct list_head to use as a loop cursor.
365 * @head: the head for your list.
367 #define list_for_each(pos, head) \
368 for (pos = (head)->next; prefetch(pos->next), pos != (head); \
372 * __list_for_each - iterate over a list
373 * @pos: the &struct list_head to use as a loop cursor.
374 * @head: the head for your list.
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.
381 #define __list_for_each(pos, head) \
382 for (pos = (head)->next; pos != (head); pos = pos->next)
385 * list_for_each_prev - iterate over a list backwards
386 * @pos: the &struct list_head to use as a loop cursor.
387 * @head: the head for your list.
389 #define list_for_each_prev(pos, head) \
390 for (pos = (head)->prev; prefetch(pos->prev), pos != (head); \
394 * list_for_each_safe - iterate over a list safe against removal of list entry
395 * @pos: the &struct list_head to use as a loop cursor.
396 * @n: another &struct list_head to use as temporary storage
397 * @head: the head for your list.
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)
404 * list_for_each_prev_safe - iterate over a list backwards safe against removal of list entry
405 * @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.
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)
415 * list_for_each_entry - iterate over list of given type
416 * @pos: the type * to use as a loop cursor.
417 * @head: the head for your list.
418 * @member: the name of the list_struct within the struct.
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))
426 * list_for_each_entry_reverse - iterate backwards over list of given type.
427 * @pos: the type * to use as a loop cursor.
428 * @head: the head for your list.
429 * @member: the name of the list_struct within the struct.
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))
437 * list_prepare_entry - prepare a pos entry for use in list_for_each_entry_continue()
438 * @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.
442 * Prepares a pos entry for use as a start point in list_for_each_entry_continue().
444 #define list_prepare_entry(pos, head, member) \
445 ((pos) ? : list_entry(head, typeof(*pos), member))
448 * list_for_each_entry_continue - continue iteration over list of given type
449 * @pos: the type * to use as a loop cursor.
450 * @head: the head for your list.
451 * @member: the name of the list_struct within the struct.
453 * Continue to iterate over list of given type, continuing after
454 * the current position.
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))
462 * 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.
467 * Start to iterate over list of given type backwards, continuing after
468 * the current position.
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))
476 * list_for_each_entry_from - iterate over list of given type from the current point
477 * @pos: the type * to use as a loop cursor.
478 * @head: the head for your list.
479 * @member: the name of the list_struct within the struct.
481 * Iterate over list of given type, continuing from current position.
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))
488 * list_for_each_entry_safe - iterate over list of given type safe against removal of list entry
489 * @pos: the type * to use as a loop cursor.
490 * @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.
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))
501 * list_for_each_entry_safe_continue - continue list iteration safe against removal
502 * @pos: the type * to use as a loop cursor.
503 * @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.
507 * Iterate over list of given type, continuing after current point,
508 * safe against removal of list entry.
510 #define list_for_each_entry_safe_continue(pos, n, head, member) \
511 for (pos = list_entry(pos->member.next, typeof(*pos), member), \
512 n = list_entry(pos->member.next, typeof(*pos), member); \
513 &pos->member != (head); \
514 pos = n, n = list_entry(n->member.next, typeof(*n), member))
517 * list_for_each_entry_safe_from - iterate over list from current point safe against removal
518 * @pos: the type * to use as a loop cursor.
519 * @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.
523 * Iterate over list of given type from current point, safe against
524 * removal of list entry.
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))
532 * list_for_each_entry_safe_reverse - iterate backwards over list safe against removal
533 * @pos: the type * to use as a loop cursor.
534 * @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.
538 * Iterate backwards over list of given type, safe against removal
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))
548 * Double linked lists with a single pointer list head.
549 * Mostly useful for hash tables where the two pointer list head is
551 * You lose the ability to access the tail in O(1).
555 struct hlist_node
*first
;
559 struct hlist_node
*next
, **pprev
;
562 #define HLIST_HEAD_INIT { .first = NULL }
563 #define HLIST_HEAD(name) struct hlist_head name = { .first = NULL }
564 #define INIT_HLIST_HEAD(ptr) ((ptr)->first = NULL)
565 static inline void INIT_HLIST_NODE(struct hlist_node
*h
)
571 static inline int hlist_unhashed(const struct hlist_node
*h
)
576 static inline int hlist_empty(const struct hlist_head
*h
)
581 static inline void __hlist_del(struct hlist_node
*n
)
583 struct hlist_node
*next
= n
->next
;
584 struct hlist_node
**pprev
= n
->pprev
;
590 static inline void hlist_del(struct hlist_node
*n
)
593 n
->next
= LIST_POISON1
;
594 n
->pprev
= LIST_POISON2
;
597 static inline void hlist_del_init(struct hlist_node
*n
)
599 if (!hlist_unhashed(n
)) {
605 static inline void hlist_add_head(struct hlist_node
*n
, struct hlist_head
*h
)
607 struct hlist_node
*first
= h
->first
;
610 first
->pprev
= &n
->next
;
612 n
->pprev
= &h
->first
;
615 /* next must be != NULL */
616 static inline void hlist_add_before(struct hlist_node
*n
,
617 struct hlist_node
*next
)
619 n
->pprev
= next
->pprev
;
621 next
->pprev
= &n
->next
;
625 static inline void hlist_add_after(struct hlist_node
*n
,
626 struct hlist_node
*next
)
628 next
->next
= n
->next
;
630 next
->pprev
= &n
->next
;
633 next
->next
->pprev
= &next
->next
;
637 * Move a list from one list head to another. Fixup the pprev
638 * reference of the first entry if it exists.
640 static inline void hlist_move_list(struct hlist_head
*old
,
641 struct hlist_head
*new)
643 new->first
= old
->first
;
645 new->first
->pprev
= &new->first
;
649 #define hlist_entry(ptr, type, member) container_of(ptr,type,member)
651 #define hlist_for_each(pos, head) \
652 for (pos = (head)->first; pos && ({ prefetch(pos->next); 1; }); \
655 #define hlist_for_each_safe(pos, n, head) \
656 for (pos = (head)->first; pos && ({ n = pos->next; 1; }); \
660 * hlist_for_each_entry - iterate over list of given type
661 * @tpos: the type * to use as a loop cursor.
662 * @pos: the &struct hlist_node to use as a loop cursor.
663 * @head: the head for your list.
664 * @member: the name of the hlist_node within the struct.
666 #define hlist_for_each_entry(tpos, pos, head, member) \
667 for (pos = (head)->first; \
668 pos && ({ prefetch(pos->next); 1;}) && \
669 ({ tpos = hlist_entry(pos, typeof(*tpos), member); 1;}); \
673 * hlist_for_each_entry_continue - iterate over a hlist continuing after current point
674 * @tpos: the type * to use as a loop cursor.
675 * @pos: the &struct hlist_node to use as a loop cursor.
676 * @member: the name of the hlist_node within the struct.
678 #define hlist_for_each_entry_continue(tpos, pos, member) \
679 for (pos = (pos)->next; \
680 pos && ({ prefetch(pos->next); 1;}) && \
681 ({ tpos = hlist_entry(pos, typeof(*tpos), member); 1;}); \
685 * hlist_for_each_entry_from - iterate over a hlist continuing from current point
686 * @tpos: the type * to use as a loop cursor.
687 * @pos: the &struct hlist_node to use as a loop cursor.
688 * @member: the name of the hlist_node within the struct.
690 #define hlist_for_each_entry_from(tpos, pos, member) \
691 for (; pos && ({ prefetch(pos->next); 1;}) && \
692 ({ tpos = hlist_entry(pos, typeof(*tpos), member); 1;}); \
696 * hlist_for_each_entry_safe - iterate over list of given type safe against removal of list entry
697 * @tpos: the type * to use as a loop cursor.
698 * @pos: the &struct hlist_node to use as a loop cursor.
699 * @n: another &struct hlist_node to use as temporary storage
700 * @head: the head for your list.
701 * @member: the name of the hlist_node within the struct.
703 #define hlist_for_each_entry_safe(tpos, pos, n, head, member) \
704 for (pos = (head)->first; \
705 pos && ({ n = pos->next; 1; }) && \
706 ({ tpos = hlist_entry(pos, typeof(*tpos), member); 1;}); \