4 #include <linux/types.h>
5 #include <linux/stddef.h>
6 #include <linux/poison.h>
7 #include <linux/const.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.
19 #define LIST_HEAD_INIT(name) { &(name), &(name) }
21 #define LIST_HEAD(name) \
22 struct list_head name = LIST_HEAD_INIT(name)
24 static inline void INIT_LIST_HEAD(struct list_head
*list
)
31 * Insert a new entry between two known consecutive entries.
33 * This is only for internal list manipulation where we know
34 * the prev/next entries already!
36 #ifndef CONFIG_DEBUG_LIST
37 static inline void __list_add(struct list_head
*new,
38 struct list_head
*prev
,
39 struct list_head
*next
)
47 extern void __list_add(struct list_head
*new,
48 struct list_head
*prev
,
49 struct list_head
*next
);
53 * list_add - add a new entry
54 * @new: new entry to be added
55 * @head: list head to add it after
57 * Insert a new entry after the specified head.
58 * This is good for implementing stacks.
60 static inline void list_add(struct list_head
*new, struct list_head
*head
)
62 __list_add(new, head
, head
->next
);
67 * list_add_tail - add a new entry
68 * @new: new entry to be added
69 * @head: list head to add it before
71 * Insert a new entry before the specified head.
72 * This is useful for implementing queues.
74 static inline void list_add_tail(struct list_head
*new, struct list_head
*head
)
76 __list_add(new, head
->prev
, head
);
80 * Delete a list entry by making the prev/next entries
81 * point to each other.
83 * This is only for internal list manipulation where we know
84 * the prev/next entries already!
86 static inline void __list_del(struct list_head
* prev
, struct list_head
* next
)
93 * list_del - deletes entry from list.
94 * @entry: the element to delete from the list.
95 * Note: list_empty() on entry does not return true after this, the entry is
96 * in an undefined state.
98 #ifndef CONFIG_DEBUG_LIST
99 static inline void __list_del_entry(struct list_head
*entry
)
101 __list_del(entry
->prev
, entry
->next
);
104 static inline void list_del(struct list_head
*entry
)
106 __list_del(entry
->prev
, entry
->next
);
107 entry
->next
= LIST_POISON1
;
108 entry
->prev
= LIST_POISON2
;
111 extern void __list_del_entry(struct list_head
*entry
);
112 extern void list_del(struct list_head
*entry
);
116 * list_replace - replace old entry by new one
117 * @old : the element to be replaced
118 * @new : the new element to insert
120 * If @old was empty, it will be overwritten.
122 static inline void list_replace(struct list_head
*old
,
123 struct list_head
*new)
125 new->next
= old
->next
;
126 new->next
->prev
= new;
127 new->prev
= old
->prev
;
128 new->prev
->next
= new;
131 static inline void list_replace_init(struct list_head
*old
,
132 struct list_head
*new)
134 list_replace(old
, new);
139 * list_del_init - deletes entry from list and reinitialize it.
140 * @entry: the element to delete from the list.
142 static inline void list_del_init(struct list_head
*entry
)
144 __list_del_entry(entry
);
145 INIT_LIST_HEAD(entry
);
149 * list_move - delete from one list and add as another's head
150 * @list: the entry to move
151 * @head: the head that will precede our entry
153 static inline void list_move(struct list_head
*list
, struct list_head
*head
)
155 __list_del_entry(list
);
156 list_add(list
, head
);
160 * list_move_tail - delete from one list and add as another's tail
161 * @list: the entry to move
162 * @head: the head that will follow our entry
164 static inline void list_move_tail(struct list_head
*list
,
165 struct list_head
*head
)
167 __list_del_entry(list
);
168 list_add_tail(list
, head
);
172 * list_is_last - tests whether @list is the last entry in list @head
173 * @list: the entry to test
174 * @head: the head of the list
176 static inline int list_is_last(const struct list_head
*list
,
177 const struct list_head
*head
)
179 return list
->next
== head
;
183 * list_empty - tests whether a list is empty
184 * @head: the list to test.
186 static inline int list_empty(const struct list_head
*head
)
188 return head
->next
== head
;
192 * list_empty_careful - tests whether a list is empty and not being modified
193 * @head: the list to test
196 * tests whether a list is empty _and_ checks that no other CPU might be
197 * in the process of modifying either member (next or prev)
199 * NOTE: using list_empty_careful() without synchronization
200 * can only be safe if the only activity that can happen
201 * to the list entry is list_del_init(). Eg. it cannot be used
202 * if another CPU could re-list_add() it.
204 static inline int list_empty_careful(const struct list_head
*head
)
206 struct list_head
*next
= head
->next
;
207 return (next
== head
) && (next
== head
->prev
);
211 * list_rotate_left - rotate the list to the left
212 * @head: the head of the list
214 static inline void list_rotate_left(struct list_head
*head
)
216 struct list_head
*first
;
218 if (!list_empty(head
)) {
220 list_move_tail(first
, head
);
225 * list_is_singular - tests whether a list has just one entry.
226 * @head: the list to test.
228 static inline int list_is_singular(const struct list_head
*head
)
230 return !list_empty(head
) && (head
->next
== head
->prev
);
233 static inline void __list_cut_position(struct list_head
*list
,
234 struct list_head
*head
, struct list_head
*entry
)
236 struct list_head
*new_first
= entry
->next
;
237 list
->next
= head
->next
;
238 list
->next
->prev
= list
;
241 head
->next
= new_first
;
242 new_first
->prev
= head
;
246 * list_cut_position - cut a list into two
247 * @list: a new list to add all removed entries
248 * @head: a list with entries
249 * @entry: an entry within head, could be the head itself
250 * and if so we won't cut the list
252 * This helper moves the initial part of @head, up to and
253 * including @entry, from @head to @list. You should
254 * pass on @entry an element you know is on @head. @list
255 * should be an empty list or a list you do not care about
259 static inline void list_cut_position(struct list_head
*list
,
260 struct list_head
*head
, struct list_head
*entry
)
262 if (list_empty(head
))
264 if (list_is_singular(head
) &&
265 (head
->next
!= entry
&& head
!= entry
))
268 INIT_LIST_HEAD(list
);
270 __list_cut_position(list
, head
, entry
);
273 static inline void __list_splice(const struct list_head
*list
,
274 struct list_head
*prev
,
275 struct list_head
*next
)
277 struct list_head
*first
= list
->next
;
278 struct list_head
*last
= list
->prev
;
288 * list_splice - join two lists, this is designed for stacks
289 * @list: the new list to add.
290 * @head: the place to add it in the first list.
292 static inline void list_splice(const struct list_head
*list
,
293 struct list_head
*head
)
295 if (!list_empty(list
))
296 __list_splice(list
, head
, head
->next
);
300 * list_splice_tail - join two lists, each list being a queue
301 * @list: the new list to add.
302 * @head: the place to add it in the first list.
304 static inline void list_splice_tail(struct list_head
*list
,
305 struct list_head
*head
)
307 if (!list_empty(list
))
308 __list_splice(list
, head
->prev
, head
);
312 * list_splice_init - join two lists and reinitialise the emptied list.
313 * @list: the new list to add.
314 * @head: the place to add it in the first list.
316 * The list at @list is reinitialised
318 static inline void list_splice_init(struct list_head
*list
,
319 struct list_head
*head
)
321 if (!list_empty(list
)) {
322 __list_splice(list
, head
, head
->next
);
323 INIT_LIST_HEAD(list
);
328 * list_splice_tail_init - join two lists and reinitialise the emptied list
329 * @list: the new list to add.
330 * @head: the place to add it in the first list.
332 * Each of the lists is a queue.
333 * The list at @list is reinitialised
335 static inline void list_splice_tail_init(struct list_head
*list
,
336 struct list_head
*head
)
338 if (!list_empty(list
)) {
339 __list_splice(list
, head
->prev
, head
);
340 INIT_LIST_HEAD(list
);
345 * list_entry - get the struct for this entry
346 * @ptr: the &struct list_head pointer.
347 * @type: the type of the struct this is embedded in.
348 * @member: the name of the list_struct within the struct.
350 #define list_entry(ptr, type, member) \
351 container_of(ptr, type, member)
354 * list_first_entry - get the first element from a list
355 * @ptr: the list head to take the element from.
356 * @type: the type of the struct this is embedded in.
357 * @member: the name of the list_struct within the struct.
359 * Note, that list is expected to be not empty.
361 #define list_first_entry(ptr, type, member) \
362 list_entry((ptr)->next, type, member)
365 * list_for_each - iterate over a list
366 * @pos: the &struct list_head to use as a loop cursor.
367 * @head: the head for your list.
369 #define list_for_each(pos, head) \
370 for (pos = (head)->next; pos != (head); pos = pos->next)
373 * __list_for_each - iterate over a list
374 * @pos: the &struct list_head to use as a loop cursor.
375 * @head: the head for your list.
377 * This variant doesn't differ from list_for_each() any more.
378 * We don't do prefetching in either case.
380 #define __list_for_each(pos, head) \
381 for (pos = (head)->next; pos != (head); pos = pos->next)
384 * list_for_each_prev - iterate over a list backwards
385 * @pos: the &struct list_head to use as a loop cursor.
386 * @head: the head for your list.
388 #define list_for_each_prev(pos, head) \
389 for (pos = (head)->prev; pos != (head); pos = pos->prev)
392 * list_for_each_safe - iterate over a list safe against removal of list entry
393 * @pos: the &struct list_head to use as a loop cursor.
394 * @n: another &struct list_head to use as temporary storage
395 * @head: the head for your list.
397 #define list_for_each_safe(pos, n, head) \
398 for (pos = (head)->next, n = pos->next; pos != (head); \
399 pos = n, n = pos->next)
402 * list_for_each_prev_safe - iterate over a list backwards safe against removal of list entry
403 * @pos: the &struct list_head to use as a loop cursor.
404 * @n: another &struct list_head to use as temporary storage
405 * @head: the head for your list.
407 #define list_for_each_prev_safe(pos, n, head) \
408 for (pos = (head)->prev, n = pos->prev; \
410 pos = n, n = pos->prev)
413 * list_for_each_entry - iterate over list of given type
414 * @pos: the type * to use as a loop cursor.
415 * @head: the head for your list.
416 * @member: the name of the list_struct within the struct.
418 #define list_for_each_entry(pos, head, member) \
419 for (pos = list_entry((head)->next, typeof(*pos), member); \
420 &pos->member != (head); \
421 pos = list_entry(pos->member.next, typeof(*pos), member))
424 * list_for_each_entry_reverse - iterate backwards over list of given type.
425 * @pos: the type * to use as a loop cursor.
426 * @head: the head for your list.
427 * @member: the name of the list_struct within the struct.
429 #define list_for_each_entry_reverse(pos, head, member) \
430 for (pos = list_entry((head)->prev, typeof(*pos), member); \
431 &pos->member != (head); \
432 pos = list_entry(pos->member.prev, typeof(*pos), member))
435 * list_prepare_entry - prepare a pos entry for use in list_for_each_entry_continue()
436 * @pos: the type * to use as a start point
437 * @head: the head of the list
438 * @member: the name of the list_struct within the struct.
440 * Prepares a pos entry for use as a start point in list_for_each_entry_continue().
442 #define list_prepare_entry(pos, head, member) \
443 ((pos) ? : list_entry(head, typeof(*pos), member))
446 * list_for_each_entry_continue - continue iteration over list of given type
447 * @pos: the type * to use as a loop cursor.
448 * @head: the head for your list.
449 * @member: the name of the list_struct within the struct.
451 * Continue to iterate over list of given type, continuing after
452 * the current position.
454 #define list_for_each_entry_continue(pos, head, member) \
455 for (pos = list_entry(pos->member.next, typeof(*pos), member); \
456 &pos->member != (head); \
457 pos = list_entry(pos->member.next, typeof(*pos), member))
460 * list_for_each_entry_continue_reverse - iterate backwards from the given point
461 * @pos: the type * to use as a loop cursor.
462 * @head: the head for your list.
463 * @member: the name of the list_struct within the struct.
465 * Start to iterate over list of given type backwards, continuing after
466 * the current position.
468 #define list_for_each_entry_continue_reverse(pos, head, member) \
469 for (pos = list_entry(pos->member.prev, typeof(*pos), member); \
470 &pos->member != (head); \
471 pos = list_entry(pos->member.prev, typeof(*pos), member))
474 * list_for_each_entry_from - iterate over list of given type from the current point
475 * @pos: the type * to use as a loop cursor.
476 * @head: the head for your list.
477 * @member: the name of the list_struct within the struct.
479 * Iterate over list of given type, continuing from current position.
481 #define list_for_each_entry_from(pos, head, member) \
482 for (; &pos->member != (head); \
483 pos = list_entry(pos->member.next, typeof(*pos), member))
486 * list_for_each_entry_safe - iterate over list of given type safe against removal of list entry
487 * @pos: the type * to use as a loop cursor.
488 * @n: another type * to use as temporary storage
489 * @head: the head for your list.
490 * @member: the name of the list_struct within the struct.
492 #define list_for_each_entry_safe(pos, n, head, member) \
493 for (pos = list_entry((head)->next, typeof(*pos), member), \
494 n = list_entry(pos->member.next, typeof(*pos), member); \
495 &pos->member != (head); \
496 pos = n, n = list_entry(n->member.next, typeof(*n), member))
499 * list_for_each_entry_safe_continue - continue list iteration safe against removal
500 * @pos: the type * to use as a loop cursor.
501 * @n: another type * to use as temporary storage
502 * @head: the head for your list.
503 * @member: the name of the list_struct within the struct.
505 * Iterate over list of given type, continuing after current point,
506 * safe against removal of list entry.
508 #define list_for_each_entry_safe_continue(pos, n, head, member) \
509 for (pos = list_entry(pos->member.next, typeof(*pos), member), \
510 n = list_entry(pos->member.next, typeof(*pos), member); \
511 &pos->member != (head); \
512 pos = n, n = list_entry(n->member.next, typeof(*n), member))
515 * list_for_each_entry_safe_from - iterate over list from current point safe against removal
516 * @pos: the type * to use as a loop cursor.
517 * @n: another type * to use as temporary storage
518 * @head: the head for your list.
519 * @member: the name of the list_struct within the struct.
521 * Iterate over list of given type from current point, safe against
522 * removal of list entry.
524 #define list_for_each_entry_safe_from(pos, n, head, member) \
525 for (n = list_entry(pos->member.next, typeof(*pos), member); \
526 &pos->member != (head); \
527 pos = n, n = list_entry(n->member.next, typeof(*n), member))
530 * list_for_each_entry_safe_reverse - iterate backwards over list safe against removal
531 * @pos: the type * to use as a loop cursor.
532 * @n: another type * to use as temporary storage
533 * @head: the head for your list.
534 * @member: the name of the list_struct within the struct.
536 * Iterate backwards over list of given type, safe against removal
539 #define list_for_each_entry_safe_reverse(pos, n, head, member) \
540 for (pos = list_entry((head)->prev, typeof(*pos), member), \
541 n = list_entry(pos->member.prev, typeof(*pos), member); \
542 &pos->member != (head); \
543 pos = n, n = list_entry(n->member.prev, typeof(*n), member))
546 * list_safe_reset_next - reset a stale list_for_each_entry_safe loop
547 * @pos: the loop cursor used in the list_for_each_entry_safe loop
548 * @n: temporary storage used in list_for_each_entry_safe
549 * @member: the name of the list_struct within the struct.
551 * list_safe_reset_next is not safe to use in general if the list may be
552 * modified concurrently (eg. the lock is dropped in the loop body). An
553 * exception to this is if the cursor element (pos) is pinned in the list,
554 * and list_safe_reset_next is called after re-taking the lock and before
555 * completing the current iteration of the loop body.
557 #define list_safe_reset_next(pos, n, member) \
558 n = list_entry(pos->member.next, typeof(*pos), member)
561 * Double linked lists with a single pointer list head.
562 * Mostly useful for hash tables where the two pointer list head is
564 * You lose the ability to access the tail in O(1).
567 #define HLIST_HEAD_INIT { .first = NULL }
568 #define HLIST_HEAD(name) struct hlist_head name = { .first = NULL }
569 #define INIT_HLIST_HEAD(ptr) ((ptr)->first = NULL)
570 static inline void INIT_HLIST_NODE(struct hlist_node
*h
)
576 static inline int hlist_unhashed(const struct hlist_node
*h
)
581 static inline int hlist_empty(const struct hlist_head
*h
)
586 static inline void __hlist_del(struct hlist_node
*n
)
588 struct hlist_node
*next
= n
->next
;
589 struct hlist_node
**pprev
= n
->pprev
;
595 static inline void hlist_del(struct hlist_node
*n
)
598 n
->next
= LIST_POISON1
;
599 n
->pprev
= LIST_POISON2
;
602 static inline void hlist_del_init(struct hlist_node
*n
)
604 if (!hlist_unhashed(n
)) {
610 static inline void hlist_add_head(struct hlist_node
*n
, struct hlist_head
*h
)
612 struct hlist_node
*first
= h
->first
;
615 first
->pprev
= &n
->next
;
617 n
->pprev
= &h
->first
;
620 /* next must be != NULL */
621 static inline void hlist_add_before(struct hlist_node
*n
,
622 struct hlist_node
*next
)
624 n
->pprev
= next
->pprev
;
626 next
->pprev
= &n
->next
;
630 static inline void hlist_add_after(struct hlist_node
*n
,
631 struct hlist_node
*next
)
633 next
->next
= n
->next
;
635 next
->pprev
= &n
->next
;
638 next
->next
->pprev
= &next
->next
;
641 /* after that we'll appear to be on some hlist and hlist_del will work */
642 static inline void hlist_add_fake(struct hlist_node
*n
)
648 * Move a list from one list head to another. Fixup the pprev
649 * reference of the first entry if it exists.
651 static inline void hlist_move_list(struct hlist_head
*old
,
652 struct hlist_head
*new)
654 new->first
= old
->first
;
656 new->first
->pprev
= &new->first
;
660 #define hlist_entry(ptr, type, member) container_of(ptr,type,member)
662 #define hlist_for_each(pos, head) \
663 for (pos = (head)->first; pos ; pos = pos->next)
665 #define hlist_for_each_safe(pos, n, head) \
666 for (pos = (head)->first; pos && ({ n = pos->next; 1; }); \
670 * hlist_for_each_entry - iterate over list of given type
671 * @tpos: the type * to use as a loop cursor.
672 * @pos: the &struct hlist_node to use as a loop cursor.
673 * @head: the head for your list.
674 * @member: the name of the hlist_node within the struct.
676 #define hlist_for_each_entry(tpos, pos, head, member) \
677 for (pos = (head)->first; \
679 ({ tpos = hlist_entry(pos, typeof(*tpos), member); 1;}); \
683 * hlist_for_each_entry_continue - iterate over a hlist continuing after current point
684 * @tpos: the type * to use as a loop cursor.
685 * @pos: the &struct hlist_node to use as a loop cursor.
686 * @member: the name of the hlist_node within the struct.
688 #define hlist_for_each_entry_continue(tpos, pos, member) \
689 for (pos = (pos)->next; \
691 ({ tpos = hlist_entry(pos, typeof(*tpos), member); 1;}); \
695 * hlist_for_each_entry_from - iterate over a hlist continuing from current point
696 * @tpos: the type * to use as a loop cursor.
697 * @pos: the &struct hlist_node to use as a loop cursor.
698 * @member: the name of the hlist_node within the struct.
700 #define hlist_for_each_entry_from(tpos, pos, member) \
702 ({ tpos = hlist_entry(pos, typeof(*tpos), member); 1;}); \
706 * hlist_for_each_entry_safe - iterate over list of given type safe against removal of list entry
707 * @tpos: the type * to use as a loop cursor.
708 * @pos: the &struct hlist_node to use as a loop cursor.
709 * @n: another &struct hlist_node to use as temporary storage
710 * @head: the head for your list.
711 * @member: the name of the hlist_node within the struct.
713 #define hlist_for_each_entry_safe(tpos, pos, n, head, member) \
714 for (pos = (head)->first; \
715 pos && ({ n = pos->next; 1; }) && \
716 ({ tpos = hlist_entry(pos, typeof(*tpos), member); 1;}); \
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