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_is_singular - tests whether a list has just one entry.
210 * @head: the list to test.
212 static inline int list_is_singular(const struct list_head *head)
214 return !list_empty(head) && (head->next == head->prev);
217 static inline void __list_splice(const struct list_head *list,
218 struct list_head *prev,
219 struct list_head *next)
221 struct list_head *first = list->next;
222 struct list_head *last = list->prev;
232 * list_splice - join two lists, this is designed for stacks
233 * @list: the new list to add.
234 * @head: the place to add it in the first list.
236 static inline void list_splice(const struct list_head *list,
237 struct list_head *head)
239 if (!list_empty(list))
240 __list_splice(list, head, head->next);
244 * list_splice_tail - join two lists, each list being a queue
245 * @list: the new list to add.
246 * @head: the place to add it in the first list.
248 static inline void list_splice_tail(struct list_head *list,
249 struct list_head *head)
251 if (!list_empty(list))
252 __list_splice(list, head->prev, head);
256 * list_splice_init - join two lists and reinitialise the emptied list.
257 * @list: the new list to add.
258 * @head: the place to add it in the first list.
260 * The list at @list is reinitialised
262 static inline void list_splice_init(struct list_head *list,
263 struct list_head *head)
265 if (!list_empty(list)) {
266 __list_splice(list, head, head->next);
267 INIT_LIST_HEAD(list);
272 * list_splice_tail_init - join two lists, each list being a queue, and
273 * reinitialise the emptied list.
274 * @list: the new list to add.
275 * @head: the place to add it in the first list.
277 * The list at @list is reinitialised
279 static inline void list_splice_tail_init(struct list_head *list,
280 struct list_head *head)
282 if (!list_empty(list)) {
283 __list_splice(list, head->prev, head);
284 INIT_LIST_HEAD(list);
289 * list_entry - get the struct for this entry
290 * @ptr: the &struct list_head pointer.
291 * @type: the type of the struct this is embedded in.
292 * @member: the name of the list_struct within the struct.
294 #define list_entry(ptr, type, member) \
295 container_of(ptr, type, member)
298 * list_first_entry - get the first element from a list
299 * @ptr: the list head to take the element from.
300 * @type: the type of the struct this is embedded in.
301 * @member: the name of the list_struct within the struct.
303 * Note, that list is expected to be not empty.
305 #define list_first_entry(ptr, type, member) \
306 list_entry((ptr)->next, type, member)
309 * list_for_each - iterate over a list
310 * @pos: the &struct list_head to use as a loop cursor.
311 * @head: the head for your list.
313 #define list_for_each(pos, head) \
314 for (pos = (head)->next; prefetch(pos->next), pos != (head); \
318 * __list_for_each - iterate over a list
319 * @pos: the &struct list_head to use as a loop cursor.
320 * @head: the head for your list.
322 * This variant differs from list_for_each() in that it's the
323 * simplest possible list iteration code, no prefetching is done.
324 * Use this for code that knows the list to be very short (empty
325 * or 1 entry) most of the time.
327 #define __list_for_each(pos, head) \
328 for (pos = (head)->next; pos != (head); pos = pos->next)
331 * list_for_each_prev - iterate over a list backwards
332 * @pos: the &struct list_head to use as a loop cursor.
333 * @head: the head for your list.
335 #define list_for_each_prev(pos, head) \
336 for (pos = (head)->prev; prefetch(pos->prev), pos != (head); \
340 * list_for_each_safe - iterate over a list safe against removal of list entry
341 * @pos: the &struct list_head to use as a loop cursor.
342 * @n: another &struct list_head to use as temporary storage
343 * @head: the head for your list.
345 #define list_for_each_safe(pos, n, head) \
346 for (pos = (head)->next, n = pos->next; pos != (head); \
347 pos = n, n = pos->next)
350 * list_for_each_prev_safe - iterate over a list backwards safe against removal of list entry
351 * @pos: the &struct list_head to use as a loop cursor.
352 * @n: another &struct list_head to use as temporary storage
353 * @head: the head for your list.
355 #define list_for_each_prev_safe(pos, n, head) \
356 for (pos = (head)->prev, n = pos->prev; \
357 prefetch(pos->prev), pos != (head); \
358 pos = n, n = pos->prev)
361 * list_for_each_entry - iterate over list of given type
362 * @pos: the type * to use as a loop cursor.
363 * @head: the head for your list.
364 * @member: the name of the list_struct within the struct.
366 #define list_for_each_entry(pos, head, member) \
367 for (pos = list_entry((head)->next, typeof(*pos), member); \
368 prefetch(pos->member.next), &pos->member != (head); \
369 pos = list_entry(pos->member.next, typeof(*pos), member))
372 * list_for_each_entry_reverse - iterate backwards over list of given type.
373 * @pos: the type * to use as a loop cursor.
374 * @head: the head for your list.
375 * @member: the name of the list_struct within the struct.
377 #define list_for_each_entry_reverse(pos, head, member) \
378 for (pos = list_entry((head)->prev, typeof(*pos), member); \
379 prefetch(pos->member.prev), &pos->member != (head); \
380 pos = list_entry(pos->member.prev, typeof(*pos), member))
383 * list_prepare_entry - prepare a pos entry for use in list_for_each_entry_continue()
384 * @pos: the type * to use as a start point
385 * @head: the head of the list
386 * @member: the name of the list_struct within the struct.
388 * Prepares a pos entry for use as a start point in list_for_each_entry_continue().
390 #define list_prepare_entry(pos, head, member) \
391 ((pos) ? : list_entry(head, typeof(*pos), member))
394 * list_for_each_entry_continue - continue iteration over list of given type
395 * @pos: the type * to use as a loop cursor.
396 * @head: the head for your list.
397 * @member: the name of the list_struct within the struct.
399 * Continue to iterate over list of given type, continuing after
400 * the current position.
402 #define list_for_each_entry_continue(pos, head, member) \
403 for (pos = list_entry(pos->member.next, typeof(*pos), member); \
404 prefetch(pos->member.next), &pos->member != (head); \
405 pos = list_entry(pos->member.next, typeof(*pos), member))
408 * list_for_each_entry_continue_reverse - iterate backwards from the given point
409 * @pos: the type * to use as a loop cursor.
410 * @head: the head for your list.
411 * @member: the name of the list_struct within the struct.
413 * Start to iterate over list of given type backwards, continuing after
414 * the current position.
416 #define list_for_each_entry_continue_reverse(pos, head, member) \
417 for (pos = list_entry(pos->member.prev, typeof(*pos), member); \
418 prefetch(pos->member.prev), &pos->member != (head); \
419 pos = list_entry(pos->member.prev, typeof(*pos), member))
422 * list_for_each_entry_from - iterate over list of given type from the current point
423 * @pos: the type * to use as a loop cursor.
424 * @head: the head for your list.
425 * @member: the name of the list_struct within the struct.
427 * Iterate over list of given type, continuing from current position.
429 #define list_for_each_entry_from(pos, head, member) \
430 for (; prefetch(pos->member.next), &pos->member != (head); \
431 pos = list_entry(pos->member.next, typeof(*pos), member))
434 * list_for_each_entry_safe - iterate over list of given type safe against removal of list entry
435 * @pos: the type * to use as a loop cursor.
436 * @n: another type * to use as temporary storage
437 * @head: the head for your list.
438 * @member: the name of the list_struct within the struct.
440 #define list_for_each_entry_safe(pos, n, head, member) \
441 for (pos = list_entry((head)->next, typeof(*pos), member), \
442 n = list_entry(pos->member.next, typeof(*pos), member); \
443 &pos->member != (head); \
444 pos = n, n = list_entry(n->member.next, typeof(*n), member))
447 * list_for_each_entry_safe_continue
448 * @pos: the type * to use as a loop cursor.
449 * @n: another type * to use as temporary storage
450 * @head: the head for your list.
451 * @member: the name of the list_struct within the struct.
453 * Iterate over list of given type, continuing after current point,
454 * safe against removal of list entry.
456 #define list_for_each_entry_safe_continue(pos, n, head, member) \
457 for (pos = list_entry(pos->member.next, typeof(*pos), member), \
458 n = list_entry(pos->member.next, typeof(*pos), member); \
459 &pos->member != (head); \
460 pos = n, n = list_entry(n->member.next, typeof(*n), member))
463 * list_for_each_entry_safe_from
464 * @pos: the type * to use as a loop cursor.
465 * @n: another type * to use as temporary storage
466 * @head: the head for your list.
467 * @member: the name of the list_struct within the struct.
469 * Iterate over list of given type from current point, safe against
470 * removal of list entry.
472 #define list_for_each_entry_safe_from(pos, n, head, member) \
473 for (n = list_entry(pos->member.next, typeof(*pos), member); \
474 &pos->member != (head); \
475 pos = n, n = list_entry(n->member.next, typeof(*n), member))
478 * list_for_each_entry_safe_reverse
479 * @pos: the type * to use as a loop cursor.
480 * @n: another type * to use as temporary storage
481 * @head: the head for your list.
482 * @member: the name of the list_struct within the struct.
484 * Iterate backwards over list of given type, safe against removal
487 #define list_for_each_entry_safe_reverse(pos, n, head, member) \
488 for (pos = list_entry((head)->prev, typeof(*pos), member), \
489 n = list_entry(pos->member.prev, typeof(*pos), member); \
490 &pos->member != (head); \
491 pos = n, n = list_entry(n->member.prev, typeof(*n), member))
494 * Double linked lists with a single pointer list head.
495 * Mostly useful for hash tables where the two pointer list head is
497 * You lose the ability to access the tail in O(1).
501 struct hlist_node *first;
505 struct hlist_node *next, **pprev;
508 #define HLIST_HEAD_INIT { .first = NULL }
509 #define HLIST_HEAD(name) struct hlist_head name = { .first = NULL }
510 #define INIT_HLIST_HEAD(ptr) ((ptr)->first = NULL)
511 static inline void INIT_HLIST_NODE(struct hlist_node *h)
517 static inline int hlist_unhashed(const struct hlist_node *h)
522 static inline int hlist_empty(const struct hlist_head *h)
527 static inline void __hlist_del(struct hlist_node *n)
529 struct hlist_node *next = n->next;
530 struct hlist_node **pprev = n->pprev;
536 static inline void hlist_del(struct hlist_node *n)
539 n->next = LIST_POISON1;
540 n->pprev = LIST_POISON2;
543 static inline void hlist_del_init(struct hlist_node *n)
545 if (!hlist_unhashed(n)) {
551 static inline void hlist_add_head(struct hlist_node *n, struct hlist_head *h)
553 struct hlist_node *first = h->first;
556 first->pprev = &n->next;
558 n->pprev = &h->first;
561 /* next must be != NULL */
562 static inline void hlist_add_before(struct hlist_node *n,
563 struct hlist_node *next)
565 n->pprev = next->pprev;
567 next->pprev = &n->next;
571 static inline void hlist_add_after(struct hlist_node *n,
572 struct hlist_node *next)
574 next->next = n->next;
576 next->pprev = &n->next;
579 next->next->pprev = &next->next;
582 #define hlist_entry(ptr, type, member) container_of(ptr,type,member)
584 #define hlist_for_each(pos, head) \
585 for (pos = (head)->first; pos && ({ prefetch(pos->next); 1; }); \
588 #define hlist_for_each_safe(pos, n, head) \
589 for (pos = (head)->first; pos && ({ n = pos->next; 1; }); \
593 * hlist_for_each_entry - iterate over list of given type
594 * @tpos: the type * to use as a loop cursor.
595 * @pos: the &struct hlist_node to use as a loop cursor.
596 * @head: the head for your list.
597 * @member: the name of the hlist_node within the struct.
599 #define hlist_for_each_entry(tpos, pos, head, member) \
600 for (pos = (head)->first; \
601 pos && ({ prefetch(pos->next); 1;}) && \
602 ({ tpos = hlist_entry(pos, typeof(*tpos), member); 1;}); \
606 * hlist_for_each_entry_continue - iterate over a hlist continuing after current point
607 * @tpos: the type * to use as a loop cursor.
608 * @pos: the &struct hlist_node to use as a loop cursor.
609 * @member: the name of the hlist_node within the struct.
611 #define hlist_for_each_entry_continue(tpos, pos, member) \
612 for (pos = (pos)->next; \
613 pos && ({ prefetch(pos->next); 1;}) && \
614 ({ tpos = hlist_entry(pos, typeof(*tpos), member); 1;}); \
618 * hlist_for_each_entry_from - iterate over a hlist continuing from current point
619 * @tpos: the type * to use as a loop cursor.
620 * @pos: the &struct hlist_node to use as a loop cursor.
621 * @member: the name of the hlist_node within the struct.
623 #define hlist_for_each_entry_from(tpos, pos, member) \
624 for (; pos && ({ prefetch(pos->next); 1;}) && \
625 ({ tpos = hlist_entry(pos, typeof(*tpos), member); 1;}); \
629 * hlist_for_each_entry_safe - iterate over list of given type safe against removal of list entry
630 * @tpos: the type * to use as a loop cursor.
631 * @pos: the &struct hlist_node to use as a loop cursor.
632 * @n: another &struct hlist_node to use as temporary storage
633 * @head: the head for your list.
634 * @member: the name of the hlist_node within the struct.
636 #define hlist_for_each_entry_safe(tpos, pos, n, head, member) \
637 for (pos = (head)->first; \
638 pos && ({ n = pos->next; 1; }) && \
639 ({ tpos = hlist_entry(pos, typeof(*tpos), member); 1;}); \