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1#ifndef _LINUX_LIST_H
2#define _LINUX_LIST_H
3
4#include <linux/stddef.h>
5#include <linux/poison.h>
6#include <linux/prefetch.h>
7#include <asm/system.h>
8
9/*
10 * 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};
定义双向循环链表数据结构；
22
23#define LIST_HEAD_INIT(name) { &(name), &(name) }
24
25#define LIST_HEAD(name) \
26 struct list_head name = LIST_HEAD_INIT(name) //初始化链表头
27
28static inline void INIT_LIST_HEAD(struct list_head *list)
29{
30 list->next = list;
31 list->prev = list; //创建双向链表的第一个结点
32}
33
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
39 */
40#ifndef CONFIG_DEBUG_LIST
41static inline void __list_add(struct list_head *new,
42 struct list_head *prev, //传入插入位置的前一个结点
43 struct list_head *next) //传入插入位置的后一个结点
44{
45 next->prev = new;
46 new->next = next;
47 new->prev = prev;
48 prev->next = new;
49}
50#else
51extern void __list_add(struct list_head *new,
52 struct list_head *prev,
53 struct list_head *next);
54#endif
55
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}
68
69
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/*
84 * 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
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.
99 * Note: list_empty() on entry does not return true after this, the entry is
100 * in an undefined state.
101 */
102#ifndef CONFIG_DEBUG_LIST
103static 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}
109#else
110extern void list_del(struct list_head *entry);
111#endif
112
113/**
114 * list_replace - replace old entry by new one
115 * @old : the element to be replaced
116 * @new : the new element to insert
117 *
118 * If @old was empty, it will be overwritten.
119 */
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
136/**
137 * 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{
153 __list_del(list->prev, list->next);
154 list_add(list, head);
155}
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{
165 __list_del(list->prev, list->next);
166 list_add_tail(list, head);
167}
168
169/**
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
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/**
181 * 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/**
190 * 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)
196 *
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.
201 */
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
208/**
209 * list_is_singular - tests whether a list has just one entry.
210 * @head: the list to test.
211 */
212static inline int list_is_singular(const struct list_head *head)
213{
214 return !list_empty(head) && (head->next == head->prev);
215}
216
217static inline void __list_cut_position(struct list_head *list,
218 struct list_head *head, struct list_head *entry)
219{
220 struct list_head *new_first = entry->next;
221 list->next = head->next;
222 list->next->prev = list;
223 list->prev = entry;
224 entry->next = list;
225 head->next = new_first;
226 new_first->prev = head;
227}
228
229/**
230 * list_cut_position - cut a list into two
231 * @list: a new list to add all removed entries
232 * @head: a list with entries
233 * @entry: an entry within head, could be the head itself
234 * and if so we won't cut the list
235 *
236 * This helper moves the initial part of @head, up to and
237 * including @entry, from @head to @list. You should
238 * pass on @entry an element you know is on @head. @list
239 * should be an empty list or a list you do not care about
240 * losing its data.
241 *
242 */
243static inline void list_cut_position(struct list_head *list,
244 struct list_head *head, struct list_head *entry)
245{
246 if (list_empty(head))
247 return;
248 if (list_is_singular(head) &&
249 (head->next != entry && head != entry))
250 return;
251 if (entry == head)
252 INIT_LIST_HEAD(list);
253 else
254 __list_cut_position(list, head, entry);
255}
256
257static inline void __list_splice(const struct list_head *list,
258 struct list_head *prev,
259 struct list_head *next)
260{
261 struct list_head *first = list->next;
262 struct list_head *last = list->prev;
263
264 first->prev = prev;
265 prev->next = first;
266
267 last->next = next;
268 next->prev = last;
269}
270
271/**
272 * list_splice - join two lists, this is designed for stacks
273 * @list: the new list to add.
274 * @head: the place to add it in the first list.
275 */
276static inline void list_splice(const struct list_head *list,
277 struct list_head *head)
278{
279 if (!list_empty(list))
280 __list_splice(list, head, head->next);
281}
282
283/**
284 * list_splice_tail - join two lists, each list being a queue
285 * @list: the new list to add.
286 * @head: the place to add it in the first list.
287 */
288static inline void list_splice_tail(struct list_head *list,
289 struct list_head *head)
290{
291 if (!list_empty(list))
292 __list_splice(list, head->prev, head);
293}
294
295/**
296 * list_splice_init - join two lists and reinitialise the emptied list.
297 * @list: the new list to add.
298 * @head: the place to add it in the first list.
299 *
300 * The list at @list is reinitialised
301 */
302static inline void list_splice_init(struct list_head *list,
303 struct list_head *head)
304{
305 if (!list_empty(list)) {
306 __list_splice(list, head, head->next);
307 INIT_LIST_HEAD(list);
308 }
309}
310
311/**
312 * list_splice_tail_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.
315 *
316 * Each of the lists is a queue.
317 * The list at @list is reinitialised
318 */
319static inline void list_splice_tail_init(struct list_head *list,
320 struct list_head *head)
321{
322 if (!list_empty(list)) {
323 __list_splice(list, head->prev, head);
324 INIT_LIST_HEAD(list);
325 }
326}
327
328/**
329 * list_entry - get the struct for this entry
330 * @ptr: the &struct list_head pointer.
331 * @type: the type of the struct this is embedded in.
332 * @member: the name of the list_struct within the struct.
333 */
334#define list_entry(ptr, type, member) \
335 container_of(ptr, type, member)
336
337/**
338 * list_first_entry - get the first element from a list
339 * @ptr: the list head to take the element from.
340 * @type: the type of the struct this is embedded in.
341 * @member: the name of the list_struct within the struct.
342 *
343 * Note, that list is expected to be not empty.
344 */
345#define list_first_entry(ptr, type, member) \
346 list_entry((ptr)->next, type, member)
347
348/**
349 * list_for_each - iterate over a list
350 * @pos: the &struct list_head to use as a loop cursor.
351 * @head: the head for your list.
352 */
353#define list_for_each(pos, head) \
354 for (pos = (head)->next; prefetch(pos->next), pos != (head); \
355 pos = pos->next)
356
357/**
358 * __list_for_each - iterate over a list
359 * @pos: the &struct list_head to use as a loop cursor.
360 * @head: the head for your list.
361 *
362 * This variant differs from list_for_each() in that it's the
363 * simplest possible list iteration code, no prefetching is done.
364 * Use this for code that knows the list to be very short (empty
365 * or 1 entry) most of the time.
366 */
367#define __list_for_each(pos, head) \
368 for (pos = (head)->next; pos != (head); pos = pos->next)
369
370/**
371 * list_for_each_prev - iterate over a list backwards
372 * @pos: the &struct list_head to use as a loop cursor.
373 * @head: the head for your list.
374 */
375#define list_for_each_prev(pos, head) \
376 for (pos = (head)->prev; prefetch(pos->prev), pos != (head); \
377 pos = pos->prev)
378
379/**
380 * list_for_each_safe - iterate over a list safe against removal of list entry
381 * @pos: the &struct list_head to use as a loop cursor.
382 * @n: another &struct list_head to use as temporary storage
383 * @head: the head for your list.
384 */
385#define list_for_each_safe(pos, n, head) \
386 for (pos = (head)->next, n = pos->next; pos != (head); \
387 pos = n, n = pos->next)
388
389/**
390 * list_for_each_prev_safe - iterate over a list backwards safe against removal of list entry
391 * @pos: the &struct list_head to use as a loop cursor.
392 * @n: another &struct list_head to use as temporary storage
393 * @head: the head for your list.
394 */
395#define list_for_each_prev_safe(pos, n, head) \
396 for (pos = (head)->prev, n = pos->prev; \
397 prefetch(pos->prev), pos != (head); \
398 pos = n, n = pos->prev)
399
400/**
401 * list_for_each_entry - iterate over list of given type
402 * @pos: the type * to use as a loop cursor.
403 * @head: the head for your list.
404 * @member: the name of the list_struct within the struct.
405 */
406#define list_for_each_entry(pos, head, member) \
407 for (pos = list_entry((head)->next, typeof(*pos), member); \
408 prefetch(pos->member.next), &pos->member != (head); \
409 pos = list_entry(pos->member.next, typeof(*pos), member))
410
411/**
412 * list_for_each_entry_reverse - iterate backwards over list of given type.
413 * @pos: the type * to use as a loop cursor.
414 * @head: the head for your list.
415 * @member: the name of the list_struct within the struct.
416 */
417#define list_for_each_entry_reverse(pos, head, member) \
418 for (pos = list_entry((head)->prev, typeof(*pos), member); \
419 prefetch(pos->member.prev), &pos->member != (head); \
420 pos = list_entry(pos->member.prev, typeof(*pos), member))
421
422/**
423 * list_prepare_entry - prepare a pos entry for use in list_for_each_entry_continue()
424 * @pos: the type * to use as a start point
425 * @head: the head of the list
426 * @member: the name of the list_struct within the struct.
427 *
428 * Prepares a pos entry for use as a start point in list_for_each_entry_continue().
429 */
430#define list_prepare_entry(pos, head, member) \
431 ((pos) ? : list_entry(head, typeof(*pos), member))
432
433/**
434 * list_for_each_entry_continue - continue iteration over list of given type
435 * @pos: the type * to use as a loop cursor.
436 * @head: the head for your list.
437 * @member: the name of the list_struct within the struct.
438 *
439 * Continue to iterate over list of given type, continuing after
440 * the current position.
441 */
442#define list_for_each_entry_continue(pos, head, member) \
443 for (pos = list_entry(pos->member.next, typeof(*pos), member); \
444 prefetch(pos->member.next), &pos->member != (head); \
445 pos = list_entry(pos->member.next, typeof(*pos), member))
446
447/**
448 * list_for_each_entry_continue_reverse - iterate backwards from the given point
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.
452 *
453 * Start to iterate over list of given type backwards, continuing after
454 * the current position.
455 */
456#define list_for_each_entry_continue_reverse(pos, head, member) \
457 for (pos = list_entry(pos->member.prev, typeof(*pos), member); \
458 prefetch(pos->member.prev), &pos->member != (head); \
459 pos = list_entry(pos->member.prev, typeof(*pos), member))
460
461/**
462 * list_for_each_entry_from - iterate over list of given type from the current 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 * Iterate over list of given type, continuing from current position.
468 */
469#define list_for_each_entry_from(pos, head, member) \
470 for (; prefetch(pos->member.next), &pos->member != (head); \
471 pos = list_entry(pos->member.next, typeof(*pos), member))
472
473/**
474 * list_for_each_entry_safe - iterate over list of given type safe against removal of list entry
475 * @pos: the type * to use as a loop cursor.
476 * @n: another type * to use as temporary storage
477 * @head: the head for your list.
478 * @member: the name of the list_struct within the struct.
479 */
480#define list_for_each_entry_safe(pos, n, head, member) \
481 for (pos = list_entry((head)->next, typeof(*pos), member), \
482 n = list_entry(pos->member.next, typeof(*pos), member); \
483 &pos->member != (head); \
484 pos = n, n = list_entry(n->member.next, typeof(*n), member))
485
486/**
487 * list_for_each_entry_safe_continue
488 * @pos: the type * to use as a loop cursor.
489 * @n: another type * to use as temporary storage
490 * @head: the head for your list.
491 * @member: the name of the list_struct within the struct.
492 *
493 * Iterate over list of given type, continuing after current point,
494 * safe against removal of list entry.
495 */
496#define list_for_each_entry_safe_continue(pos, n, head, member) \
497 for (pos = list_entry(pos->member.next, typeof(*pos), member), \
498 n = list_entry(pos->member.next, typeof(*pos), member); \
499 &pos->member != (head); \
500 pos = n, n = list_entry(n->member.next, typeof(*n), member))
501
502/**
503 * list_for_each_entry_safe_from
504 * @pos: the type * to use as a loop cursor.
505 * @n: another type * to use as temporary storage
506 * @head: the head for your list.
507 * @member: the name of the list_struct within the struct.
508 *
509 * Iterate over list of given type from current point, safe against
510 * removal of list entry.
511 */
512#define list_for_each_entry_safe_from(pos, n, head, member) \
513 for (n = list_entry(pos->member.next, typeof(*pos), member); \
514 &pos->member != (head); \
515 pos = n, n = list_entry(n->member.next, typeof(*n), member))
516
517/**
518 * list_for_each_entry_safe_reverse
519 * @pos: the type * to use as a loop cursor.
520 * @n: another type * to use as temporary storage
521 * @head: the head for your list.
522 * @member: the name of the list_struct within the struct.
523 *
524 * Iterate backwards over list of given type, safe against removal
525 * of list entry.
526 */
527#define list_for_each_entry_safe_reverse(pos, n, head, member) \
528 for (pos = list_entry((head)->prev, typeof(*pos), member), \
529 n = list_entry(pos->member.prev, typeof(*pos), member); \
530 &pos->member != (head); \
531 pos = n, n = list_entry(n->member.prev, typeof(*n), member))
532
533/*
534 * Double linked lists with a single pointer list head.
535 * Mostly useful for hash tables where the two pointer list head is
536 * too wasteful.
537 * You lose the ability to access the tail in O(1).
538 */
539
540struct hlist_head {
541 struct hlist_node *first;
542};
543
544struct hlist_node {
545 struct hlist_node *next, **pprev;
546};
547
548#define HLIST_HEAD_INIT { .first = NULL }
549#define HLIST_HEAD(name) struct hlist_head name = { .first = NULL }
550#define INIT_HLIST_HEAD(ptr) ((ptr)->first = NULL)
551static inline void INIT_HLIST_NODE(struct hlist_node *h)
552{
553 h->next = NULL;
554 h->pprev = NULL;
555}
556
557static inline int hlist_unhashed(const struct hlist_node *h)
558{
559 return !h->pprev;
560}
561
562static inline int hlist_empty(const struct hlist_head *h)
563{
564 return !h->first;
565}
566
567static inline void __hlist_del(struct hlist_node *n)
568{
569 struct hlist_node *next = n->next;
570 struct hlist_node **pprev = n->pprev;
571 *pprev = next;
572 if (next)
573 next->pprev = pprev;
574}
575
576static inline void hlist_del(struct hlist_node *n)
577{
578 __hlist_del(n);
579 n->next = LIST_POISON1;
580 n->pprev = LIST_POISON2;
581}
582
583static inline void hlist_del_init(struct hlist_node *n)
584{
585 if (!hlist_unhashed(n)) {
586 __hlist_del(n);
587 INIT_HLIST_NODE(n);
588 }
589}
590
591static inline void hlist_add_head(struct hlist_node *n, struct hlist_head *h)
592{
593 struct hlist_node *first = h->first;
594 n->next = first;
595 if (first)
596 first->pprev = &n->next;
597 h->first = n;
598 n->pprev = &h->first;
599}
600
601/* next must be != NULL */
602static inline void hlist_add_before(struct hlist_node *n,
603 struct hlist_node *next)
604{
605 n->pprev = next->pprev;
606 n->next = next;
607 next->pprev = &n->next;
608 *(n->pprev) = n;
609}
610
611static inline void hlist_add_after(struct hlist_node *n,
612 struct hlist_node *next)
613{
614 next->next = n->next;
615 n->next = next;
616 next->pprev = &n->next;
617
618 if(next->next)
619 next->next->pprev = &next->next;
620}
621
622/*
623 * Move a list from one list head to another. Fixup the pprev
624 * reference of the first entry if it exists.
625 */
626static inline void hlist_move_list(struct hlist_head *old,
627 struct hlist_head *new)
628{
629 new->first = old->first;
630 if (new->first)
631 new->first->pprev = &new->first;
632 old->first = NULL;
633}
634
635#define hlist_entry(ptr, type, member) container_of(ptr,type,member)
636
637#define hlist_for_each(pos, head) \
638 for (pos = (head)->first; pos && ({ prefetch(pos->next); 1; }); \
639 pos = pos->next)
640
641#define hlist_for_each_safe(pos, n, head) \
642 for (pos = (head)->first; pos && ({ n = pos->next; 1; }); \
643 pos = n)
644
645/**
646 * hlist_for_each_entry - iterate over list of given type
647 * @tpos: the type * to use as a loop cursor.
648 * @pos: the &struct hlist_node to use as a loop cursor.
649 * @head: the head for your list.
650 * @member: the name of the hlist_node within the struct.
651 */
652#define hlist_for_each_entry(tpos, pos, head, member) \
653 for (pos = (head)->first; \
654 pos && ({ prefetch(pos->next); 1;}) && \
655 ({ tpos = hlist_entry(pos, typeof(*tpos), member); 1;}); \
656 pos = pos->next)
657
658/**
659 * hlist_for_each_entry_continue - iterate over a hlist continuing after current point
660 * @tpos: the type * to use as a loop cursor.
661 * @pos: the &struct hlist_node to use as a loop cursor.
662 * @member: the name of the hlist_node within the struct.
663 */
664#define hlist_for_each_entry_continue(tpos, pos, member) \
665 for (pos = (pos)->next; \
666 pos && ({ prefetch(pos->next); 1;}) && \
667 ({ tpos = hlist_entry(pos, typeof(*tpos), member); 1;}); \
668 pos = pos->next)
669
670/**
671 * hlist_for_each_entry_from - iterate over a hlist continuing from current point
672 * @tpos: the type * to use as a loop cursor.
673 * @pos: the &struct hlist_node to use as a loop cursor.
674 * @member: the name of the hlist_node within the struct.
675 */
676#define hlist_for_each_entry_from(tpos, pos, member) \
677 for (; pos && ({ prefetch(pos->next); 1;}) && \
678 ({ tpos = hlist_entry(pos, typeof(*tpos), member); 1;}); \
679 pos = pos->next)
680
681/**
682 * hlist_for_each_entry_safe - iterate over list of given type safe against removal of list entry
683 * @tpos: the type * to use as a loop cursor.
684 * @pos: the &struct hlist_node to use as a loop cursor.
685 * @n: another &struct hlist_node to use as temporary storage
686 * @head: the head for your list.
687 * @member: the name of the hlist_node within the struct.
688 */
689#define hlist_for_each_entry_safe(tpos, pos, n, head, member) \
690 for (pos = (head)->first; \
691 pos && ({ n = pos->next; 1; }) && \
692 ({ tpos = hlist_entry(pos, typeof(*tpos), member); 1;}); \
693 pos = n)
694
695#endif
696
The original LXR software by the LXR community, this experimental version by lxr@linux.no.
lxr.linux.no kindly hosted by Linpro AS, provider of Linux consulting and operations services since 1995.
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