Linux kernel mirror (for testing)
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1/* SPDX-License-Identifier: GPL-2.0 */
2#ifndef __TOOLS_LINUX_LIST_H
3#define __TOOLS_LINUX_LIST_H
4
5#include <linux/types.h>
6#include <linux/poison.h>
7#include <linux/kernel.h>
8#include <linux/compiler.h>
9
10/*
11 * Simple doubly linked list implementation.
12 *
13 * Some of the internal functions ("__xxx") are useful when
14 * manipulating whole lists rather than single entries, as
15 * sometimes we already know the next/prev entries and we can
16 * generate better code by using them directly rather than
17 * using the generic single-entry routines.
18 */
19
20#define LIST_HEAD_INIT(name) { &(name), &(name) }
21
22#define LIST_HEAD(name) \
23 struct list_head name = LIST_HEAD_INIT(name)
24
25static inline void INIT_LIST_HEAD(struct list_head *list)
26{
27 list->next = list;
28 list->prev = list;
29}
30
31/*
32 * Insert a new entry between two known consecutive entries.
33 *
34 * This is only for internal list manipulation where we know
35 * the prev/next entries already!
36 */
37#ifndef CONFIG_DEBUG_LIST
38static inline void __list_add(struct list_head *new,
39 struct list_head *prev,
40 struct list_head *next)
41{
42 next->prev = new;
43 new->next = next;
44 new->prev = prev;
45 prev->next = new;
46}
47#else
48extern void __list_add(struct list_head *new,
49 struct list_head *prev,
50 struct list_head *next);
51#endif
52
53/**
54 * list_add - add a new entry
55 * @new: new entry to be added
56 * @head: list head to add it after
57 *
58 * Insert a new entry after the specified head.
59 * This is good for implementing stacks.
60 */
61static inline void list_add(struct list_head *new, struct list_head *head)
62{
63 __list_add(new, head, head->next);
64}
65
66
67/**
68 * list_add_tail - add a new entry
69 * @new: new entry to be added
70 * @head: list head to add it before
71 *
72 * Insert a new entry before the specified head.
73 * This is useful for implementing queues.
74 */
75static inline void list_add_tail(struct list_head *new, struct list_head *head)
76{
77 __list_add(new, head->prev, head);
78}
79
80/*
81 * Delete a list entry by making the prev/next entries
82 * point to each other.
83 *
84 * This is only for internal list manipulation where we know
85 * the prev/next entries already!
86 */
87static inline void __list_del(struct list_head * prev, struct list_head * next)
88{
89 next->prev = prev;
90 WRITE_ONCE(prev->next, next);
91}
92
93/**
94 * list_del - deletes entry from list.
95 * @entry: the element to delete from the list.
96 * Note: list_empty() on entry does not return true after this, the entry is
97 * in an undefined state.
98 */
99#ifndef CONFIG_DEBUG_LIST
100static inline void __list_del_entry(struct list_head *entry)
101{
102 __list_del(entry->prev, entry->next);
103}
104
105static inline void list_del(struct list_head *entry)
106{
107 __list_del(entry->prev, entry->next);
108 entry->next = LIST_POISON1;
109 entry->prev = LIST_POISON2;
110}
111#else
112extern void __list_del_entry(struct list_head *entry);
113extern void list_del(struct list_head *entry);
114#endif
115
116/**
117 * list_replace - replace old entry by new one
118 * @old : the element to be replaced
119 * @new : the new element to insert
120 *
121 * If @old was empty, it will be overwritten.
122 */
123static inline void list_replace(struct list_head *old,
124 struct list_head *new)
125{
126 new->next = old->next;
127 new->next->prev = new;
128 new->prev = old->prev;
129 new->prev->next = new;
130}
131
132static inline void list_replace_init(struct list_head *old,
133 struct list_head *new)
134{
135 list_replace(old, new);
136 INIT_LIST_HEAD(old);
137}
138
139/**
140 * list_del_init - deletes entry from list and reinitialize it.
141 * @entry: the element to delete from the list.
142 */
143static inline void list_del_init(struct list_head *entry)
144{
145 __list_del_entry(entry);
146 INIT_LIST_HEAD(entry);
147}
148
149/**
150 * list_move - delete from one list and add as another's head
151 * @list: the entry to move
152 * @head: the head that will precede our entry
153 */
154static inline void list_move(struct list_head *list, struct list_head *head)
155{
156 __list_del_entry(list);
157 list_add(list, head);
158}
159
160/**
161 * list_move_tail - delete from one list and add as another's tail
162 * @list: the entry to move
163 * @head: the head that will follow our entry
164 */
165static inline void list_move_tail(struct list_head *list,
166 struct list_head *head)
167{
168 __list_del_entry(list);
169 list_add_tail(list, head);
170}
171
172/**
173 * list_is_first -- tests whether @list is the first entry in list @head
174 * @list: the entry to test
175 * @head: the head of the list
176 */
177static inline int list_is_first(const struct list_head *list, const struct list_head *head)
178{
179 return list->prev == head;
180}
181
182/**
183 * list_is_last - tests whether @list is the last entry in list @head
184 * @list: the entry to test
185 * @head: the head of the list
186 */
187static inline int list_is_last(const struct list_head *list,
188 const struct list_head *head)
189{
190 return list->next == head;
191}
192
193/**
194 * list_empty - tests whether a list is empty
195 * @head: the list to test.
196 */
197static inline int list_empty(const struct list_head *head)
198{
199 return head->next == head;
200}
201
202/**
203 * list_empty_careful - tests whether a list is empty and not being modified
204 * @head: the list to test
205 *
206 * Description:
207 * tests whether a list is empty _and_ checks that no other CPU might be
208 * in the process of modifying either member (next or prev)
209 *
210 * NOTE: using list_empty_careful() without synchronization
211 * can only be safe if the only activity that can happen
212 * to the list entry is list_del_init(). Eg. it cannot be used
213 * if another CPU could re-list_add() it.
214 */
215static inline int list_empty_careful(const struct list_head *head)
216{
217 struct list_head *next = head->next;
218 return (next == head) && (next == head->prev);
219}
220
221/**
222 * list_rotate_left - rotate the list to the left
223 * @head: the head of the list
224 */
225static inline void list_rotate_left(struct list_head *head)
226{
227 struct list_head *first;
228
229 if (!list_empty(head)) {
230 first = head->next;
231 list_move_tail(first, head);
232 }
233}
234
235/**
236 * list_is_singular - tests whether a list has just one entry.
237 * @head: the list to test.
238 */
239static inline int list_is_singular(const struct list_head *head)
240{
241 return !list_empty(head) && (head->next == head->prev);
242}
243
244static inline void __list_cut_position(struct list_head *list,
245 struct list_head *head, struct list_head *entry)
246{
247 struct list_head *new_first = entry->next;
248 list->next = head->next;
249 list->next->prev = list;
250 list->prev = entry;
251 entry->next = list;
252 head->next = new_first;
253 new_first->prev = head;
254}
255
256/**
257 * list_cut_position - cut a list into two
258 * @list: a new list to add all removed entries
259 * @head: a list with entries
260 * @entry: an entry within head, could be the head itself
261 * and if so we won't cut the list
262 *
263 * This helper moves the initial part of @head, up to and
264 * including @entry, from @head to @list. You should
265 * pass on @entry an element you know is on @head. @list
266 * should be an empty list or a list you do not care about
267 * losing its data.
268 *
269 */
270static inline void list_cut_position(struct list_head *list,
271 struct list_head *head, struct list_head *entry)
272{
273 if (list_empty(head))
274 return;
275 if (list_is_singular(head) &&
276 (head->next != entry && head != entry))
277 return;
278 if (entry == head)
279 INIT_LIST_HEAD(list);
280 else
281 __list_cut_position(list, head, entry);
282}
283
284static inline void __list_splice(const struct list_head *list,
285 struct list_head *prev,
286 struct list_head *next)
287{
288 struct list_head *first = list->next;
289 struct list_head *last = list->prev;
290
291 first->prev = prev;
292 prev->next = first;
293
294 last->next = next;
295 next->prev = last;
296}
297
298/**
299 * list_splice - join two lists, this is designed for stacks
300 * @list: the new list to add.
301 * @head: the place to add it in the first list.
302 */
303static inline void list_splice(const struct list_head *list,
304 struct list_head *head)
305{
306 if (!list_empty(list))
307 __list_splice(list, head, head->next);
308}
309
310/**
311 * list_splice_tail - join two lists, each list being a queue
312 * @list: the new list to add.
313 * @head: the place to add it in the first list.
314 */
315static inline void list_splice_tail(struct list_head *list,
316 struct list_head *head)
317{
318 if (!list_empty(list))
319 __list_splice(list, head->prev, head);
320}
321
322/**
323 * list_splice_init - join two lists and reinitialise the emptied list.
324 * @list: the new list to add.
325 * @head: the place to add it in the first list.
326 *
327 * The list at @list is reinitialised
328 */
329static inline void list_splice_init(struct list_head *list,
330 struct list_head *head)
331{
332 if (!list_empty(list)) {
333 __list_splice(list, head, head->next);
334 INIT_LIST_HEAD(list);
335 }
336}
337
338/**
339 * list_splice_tail_init - join two lists and reinitialise the emptied list
340 * @list: the new list to add.
341 * @head: the place to add it in the first list.
342 *
343 * Each of the lists is a queue.
344 * The list at @list is reinitialised
345 */
346static inline void list_splice_tail_init(struct list_head *list,
347 struct list_head *head)
348{
349 if (!list_empty(list)) {
350 __list_splice(list, head->prev, head);
351 INIT_LIST_HEAD(list);
352 }
353}
354
355/**
356 * list_entry - get the struct for this entry
357 * @ptr: the &struct list_head pointer.
358 * @type: the type of the struct this is embedded in.
359 * @member: the name of the list_head within the struct.
360 */
361#define list_entry(ptr, type, member) \
362 container_of(ptr, type, member)
363
364/**
365 * list_first_entry - get the first element from a list
366 * @ptr: the list head to take the element from.
367 * @type: the type of the struct this is embedded in.
368 * @member: the name of the list_head within the struct.
369 *
370 * Note, that list is expected to be not empty.
371 */
372#define list_first_entry(ptr, type, member) \
373 list_entry((ptr)->next, type, member)
374
375/**
376 * list_last_entry - get the last element from a list
377 * @ptr: the list head to take the element from.
378 * @type: the type of the struct this is embedded in.
379 * @member: the name of the list_head within the struct.
380 *
381 * Note, that list is expected to be not empty.
382 */
383#define list_last_entry(ptr, type, member) \
384 list_entry((ptr)->prev, type, member)
385
386/**
387 * list_first_entry_or_null - get the first element from a list
388 * @ptr: the list head to take the element from.
389 * @type: the type of the struct this is embedded in.
390 * @member: the name of the list_head within the struct.
391 *
392 * Note that if the list is empty, it returns NULL.
393 */
394#define list_first_entry_or_null(ptr, type, member) \
395 (!list_empty(ptr) ? list_first_entry(ptr, type, member) : NULL)
396
397/**
398 * list_last_entry_or_null - get the last element from a list
399 * @ptr: the list head to take the element from.
400 * @type: the type of the struct this is embedded in.
401 * @member: the name of the list_head within the struct.
402 *
403 * Note that if the list is empty, it returns NULL.
404 */
405#define list_last_entry_or_null(ptr, type, member) \
406 (!list_empty(ptr) ? list_last_entry(ptr, type, member) : NULL)
407
408/**
409 * list_next_entry - get the next element in list
410 * @pos: the type * to cursor
411 * @member: the name of the list_head within the struct.
412 */
413#define list_next_entry(pos, member) \
414 list_entry((pos)->member.next, typeof(*(pos)), member)
415
416/**
417 * list_prev_entry - get the prev element in list
418 * @pos: the type * to cursor
419 * @member: the name of the list_head within the struct.
420 */
421#define list_prev_entry(pos, member) \
422 list_entry((pos)->member.prev, typeof(*(pos)), member)
423
424/**
425 * list_for_each - iterate over a list
426 * @pos: the &struct list_head to use as a loop cursor.
427 * @head: the head for your list.
428 */
429#define list_for_each(pos, head) \
430 for (pos = (head)->next; pos != (head); pos = pos->next)
431
432/**
433 * list_for_each_prev - iterate over a list backwards
434 * @pos: the &struct list_head to use as a loop cursor.
435 * @head: the head for your list.
436 */
437#define list_for_each_prev(pos, head) \
438 for (pos = (head)->prev; pos != (head); pos = pos->prev)
439
440/**
441 * list_for_each_safe - iterate over a list safe against removal of list entry
442 * @pos: the &struct list_head to use as a loop cursor.
443 * @n: another &struct list_head to use as temporary storage
444 * @head: the head for your list.
445 */
446#define list_for_each_safe(pos, n, head) \
447 for (pos = (head)->next, n = pos->next; pos != (head); \
448 pos = n, n = pos->next)
449
450/**
451 * list_for_each_prev_safe - iterate over a list backwards safe against removal of list entry
452 * @pos: the &struct list_head to use as a loop cursor.
453 * @n: another &struct list_head to use as temporary storage
454 * @head: the head for your list.
455 */
456#define list_for_each_prev_safe(pos, n, head) \
457 for (pos = (head)->prev, n = pos->prev; \
458 pos != (head); \
459 pos = n, n = pos->prev)
460
461/**
462 * list_for_each_entry - iterate over list of given type
463 * @pos: the type * to use as a loop cursor.
464 * @head: the head for your list.
465 * @member: the name of the list_head within the struct.
466 */
467#define list_for_each_entry(pos, head, member) \
468 for (pos = list_first_entry(head, typeof(*pos), member); \
469 &pos->member != (head); \
470 pos = list_next_entry(pos, member))
471
472/**
473 * list_for_each_entry_reverse - iterate backwards over list of given type.
474 * @pos: the type * to use as a loop cursor.
475 * @head: the head for your list.
476 * @member: the name of the list_head within the struct.
477 */
478#define list_for_each_entry_reverse(pos, head, member) \
479 for (pos = list_last_entry(head, typeof(*pos), member); \
480 &pos->member != (head); \
481 pos = list_prev_entry(pos, member))
482
483/**
484 * list_prepare_entry - prepare a pos entry for use in list_for_each_entry_continue()
485 * @pos: the type * to use as a start point
486 * @head: the head of the list
487 * @member: the name of the list_head within the struct.
488 *
489 * Prepares a pos entry for use as a start point in list_for_each_entry_continue().
490 */
491#define list_prepare_entry(pos, head, member) \
492 ((pos) ? : list_entry(head, typeof(*pos), member))
493
494/**
495 * list_for_each_entry_continue - continue iteration over list of given type
496 * @pos: the type * to use as a loop cursor.
497 * @head: the head for your list.
498 * @member: the name of the list_head within the struct.
499 *
500 * Continue to iterate over list of given type, continuing after
501 * the current position.
502 */
503#define list_for_each_entry_continue(pos, head, member) \
504 for (pos = list_next_entry(pos, member); \
505 &pos->member != (head); \
506 pos = list_next_entry(pos, member))
507
508/**
509 * list_for_each_entry_continue_reverse - iterate backwards from the given point
510 * @pos: the type * to use as a loop cursor.
511 * @head: the head for your list.
512 * @member: the name of the list_head within the struct.
513 *
514 * Start to iterate over list of given type backwards, continuing after
515 * the current position.
516 */
517#define list_for_each_entry_continue_reverse(pos, head, member) \
518 for (pos = list_prev_entry(pos, member); \
519 &pos->member != (head); \
520 pos = list_prev_entry(pos, member))
521
522/**
523 * list_for_each_entry_from - iterate over list of given type from the current point
524 * @pos: the type * to use as a loop cursor.
525 * @head: the head for your list.
526 * @member: the name of the list_head within the struct.
527 *
528 * Iterate over list of given type, continuing from current position.
529 */
530#define list_for_each_entry_from(pos, head, member) \
531 for (; &pos->member != (head); \
532 pos = list_next_entry(pos, member))
533
534/**
535 * list_for_each_entry_safe - iterate over list of given type safe against removal of list entry
536 * @pos: the type * to use as a loop cursor.
537 * @n: another type * to use as temporary storage
538 * @head: the head for your list.
539 * @member: the name of the list_head within the struct.
540 */
541#define list_for_each_entry_safe(pos, n, head, member) \
542 for (pos = list_first_entry(head, typeof(*pos), member), \
543 n = list_next_entry(pos, member); \
544 &pos->member != (head); \
545 pos = n, n = list_next_entry(n, member))
546
547/**
548 * list_for_each_entry_safe_continue - continue list iteration safe against removal
549 * @pos: the type * to use as a loop cursor.
550 * @n: another type * to use as temporary storage
551 * @head: the head for your list.
552 * @member: the name of the list_head within the struct.
553 *
554 * Iterate over list of given type, continuing after current point,
555 * safe against removal of list entry.
556 */
557#define list_for_each_entry_safe_continue(pos, n, head, member) \
558 for (pos = list_next_entry(pos, member), \
559 n = list_next_entry(pos, member); \
560 &pos->member != (head); \
561 pos = n, n = list_next_entry(n, member))
562
563/**
564 * list_for_each_entry_safe_from - iterate over list from current point safe against removal
565 * @pos: the type * to use as a loop cursor.
566 * @n: another type * to use as temporary storage
567 * @head: the head for your list.
568 * @member: the name of the list_head within the struct.
569 *
570 * Iterate over list of given type from current point, safe against
571 * removal of list entry.
572 */
573#define list_for_each_entry_safe_from(pos, n, head, member) \
574 for (n = list_next_entry(pos, member); \
575 &pos->member != (head); \
576 pos = n, n = list_next_entry(n, member))
577
578/**
579 * list_for_each_entry_safe_reverse - iterate backwards over list safe against removal
580 * @pos: the type * to use as a loop cursor.
581 * @n: another type * to use as temporary storage
582 * @head: the head for your list.
583 * @member: the name of the list_head within the struct.
584 *
585 * Iterate backwards over list of given type, safe against removal
586 * of list entry.
587 */
588#define list_for_each_entry_safe_reverse(pos, n, head, member) \
589 for (pos = list_last_entry(head, typeof(*pos), member), \
590 n = list_prev_entry(pos, member); \
591 &pos->member != (head); \
592 pos = n, n = list_prev_entry(n, member))
593
594/**
595 * list_safe_reset_next - reset a stale list_for_each_entry_safe loop
596 * @pos: the loop cursor used in the list_for_each_entry_safe loop
597 * @n: temporary storage used in list_for_each_entry_safe
598 * @member: the name of the list_head within the struct.
599 *
600 * list_safe_reset_next is not safe to use in general if the list may be
601 * modified concurrently (eg. the lock is dropped in the loop body). An
602 * exception to this is if the cursor element (pos) is pinned in the list,
603 * and list_safe_reset_next is called after re-taking the lock and before
604 * completing the current iteration of the loop body.
605 */
606#define list_safe_reset_next(pos, n, member) \
607 n = list_next_entry(pos, member)
608
609/*
610 * Double linked lists with a single pointer list head.
611 * Mostly useful for hash tables where the two pointer list head is
612 * too wasteful.
613 * You lose the ability to access the tail in O(1).
614 */
615
616#define HLIST_HEAD_INIT { .first = NULL }
617#define HLIST_HEAD(name) struct hlist_head name = { .first = NULL }
618#define INIT_HLIST_HEAD(ptr) ((ptr)->first = NULL)
619static inline void INIT_HLIST_NODE(struct hlist_node *h)
620{
621 h->next = NULL;
622 h->pprev = NULL;
623}
624
625static inline int hlist_unhashed(const struct hlist_node *h)
626{
627 return !h->pprev;
628}
629
630static inline int hlist_empty(const struct hlist_head *h)
631{
632 return !h->first;
633}
634
635static inline void __hlist_del(struct hlist_node *n)
636{
637 struct hlist_node *next = n->next;
638 struct hlist_node **pprev = n->pprev;
639
640 WRITE_ONCE(*pprev, next);
641 if (next)
642 next->pprev = pprev;
643}
644
645static inline void hlist_del(struct hlist_node *n)
646{
647 __hlist_del(n);
648 n->next = LIST_POISON1;
649 n->pprev = LIST_POISON2;
650}
651
652static inline void hlist_del_init(struct hlist_node *n)
653{
654 if (!hlist_unhashed(n)) {
655 __hlist_del(n);
656 INIT_HLIST_NODE(n);
657 }
658}
659
660static inline void hlist_add_head(struct hlist_node *n, struct hlist_head *h)
661{
662 struct hlist_node *first = h->first;
663 n->next = first;
664 if (first)
665 first->pprev = &n->next;
666 h->first = n;
667 n->pprev = &h->first;
668}
669
670/* next must be != NULL */
671static inline void hlist_add_before(struct hlist_node *n,
672 struct hlist_node *next)
673{
674 n->pprev = next->pprev;
675 n->next = next;
676 next->pprev = &n->next;
677 *(n->pprev) = n;
678}
679
680static inline void hlist_add_behind(struct hlist_node *n,
681 struct hlist_node *prev)
682{
683 n->next = prev->next;
684 prev->next = n;
685 n->pprev = &prev->next;
686
687 if (n->next)
688 n->next->pprev = &n->next;
689}
690
691/* after that we'll appear to be on some hlist and hlist_del will work */
692static inline void hlist_add_fake(struct hlist_node *n)
693{
694 n->pprev = &n->next;
695}
696
697static inline bool hlist_fake(struct hlist_node *h)
698{
699 return h->pprev == &h->next;
700}
701
702/*
703 * Move a list from one list head to another. Fixup the pprev
704 * reference of the first entry if it exists.
705 */
706static inline void hlist_move_list(struct hlist_head *old,
707 struct hlist_head *new)
708{
709 new->first = old->first;
710 if (new->first)
711 new->first->pprev = &new->first;
712 old->first = NULL;
713}
714
715#define hlist_entry(ptr, type, member) container_of(ptr,type,member)
716
717#define hlist_for_each(pos, head) \
718 for (pos = (head)->first; pos ; pos = pos->next)
719
720#define hlist_for_each_safe(pos, n, head) \
721 for (pos = (head)->first; pos && ({ n = pos->next; 1; }); \
722 pos = n)
723
724#define hlist_entry_safe(ptr, type, member) \
725 ({ typeof(ptr) ____ptr = (ptr); \
726 ____ptr ? hlist_entry(____ptr, type, member) : NULL; \
727 })
728
729/**
730 * hlist_for_each_entry - iterate over list of given type
731 * @pos: the type * to use as a loop cursor.
732 * @head: the head for your list.
733 * @member: the name of the hlist_node within the struct.
734 */
735#define hlist_for_each_entry(pos, head, member) \
736 for (pos = hlist_entry_safe((head)->first, typeof(*(pos)), member);\
737 pos; \
738 pos = hlist_entry_safe((pos)->member.next, typeof(*(pos)), member))
739
740/**
741 * hlist_for_each_entry_continue - iterate over a hlist continuing after current point
742 * @pos: the type * to use as a loop cursor.
743 * @member: the name of the hlist_node within the struct.
744 */
745#define hlist_for_each_entry_continue(pos, member) \
746 for (pos = hlist_entry_safe((pos)->member.next, typeof(*(pos)), member);\
747 pos; \
748 pos = hlist_entry_safe((pos)->member.next, typeof(*(pos)), member))
749
750/**
751 * hlist_for_each_entry_from - iterate over a hlist continuing from current point
752 * @pos: the type * to use as a loop cursor.
753 * @member: the name of the hlist_node within the struct.
754 */
755#define hlist_for_each_entry_from(pos, member) \
756 for (; pos; \
757 pos = hlist_entry_safe((pos)->member.next, typeof(*(pos)), member))
758
759/**
760 * hlist_for_each_entry_safe - iterate over list of given type safe against removal of list entry
761 * @pos: the type * to use as a loop cursor.
762 * @n: another &struct hlist_node to use as temporary storage
763 * @head: the head for your list.
764 * @member: the name of the hlist_node within the struct.
765 */
766#define hlist_for_each_entry_safe(pos, n, head, member) \
767 for (pos = hlist_entry_safe((head)->first, typeof(*pos), member);\
768 pos && ({ n = pos->member.next; 1; }); \
769 pos = hlist_entry_safe(n, typeof(*pos), member))
770
771/**
772 * list_del_range - deletes range of entries from list.
773 * @begin: first element in the range to delete from the list.
774 * @end: last element in the range to delete from the list.
775 * Note: list_empty on the range of entries does not return true after this,
776 * the entries is in an undefined state.
777 */
778static inline void list_del_range(struct list_head *begin,
779 struct list_head *end)
780{
781 begin->prev->next = end->next;
782 end->next->prev = begin->prev;
783}
784
785/**
786 * list_for_each_from - iterate over a list from one of its nodes
787 * @pos: the &struct list_head to use as a loop cursor, from where to start
788 * @head: the head for your list.
789 */
790#define list_for_each_from(pos, head) \
791 for (; pos != (head); pos = pos->next)
792
793#endif /* __TOOLS_LINUX_LIST_H */