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b2441318 | 1 | /* SPDX-License-Identifier: GPL-2.0 */ |
1da177e4 LT |
2 | #ifndef _LINUX_LIST_H |
3 | #define _LINUX_LIST_H | |
4 | ||
cd7187e1 | 5 | #include <linux/container_of.h> |
de5d9bf6 | 6 | #include <linux/types.h> |
1da177e4 | 7 | #include <linux/stddef.h> |
c9cf5528 | 8 | #include <linux/poison.h> |
e66eed65 | 9 | #include <linux/const.h> |
cd7187e1 AS |
10 | |
11 | #include <asm/barrier.h> | |
1da177e4 | 12 | |
1da177e4 | 13 | /* |
1eafe075 | 14 | * Circular doubly linked list implementation. |
1da177e4 LT |
15 | * |
16 | * Some of the internal functions ("__xxx") are useful when | |
17 | * manipulating whole lists rather than single entries, as | |
18 | * sometimes we already know the next/prev entries and we can | |
19 | * generate better code by using them directly rather than | |
20 | * using the generic single-entry routines. | |
21 | */ | |
22 | ||
1da177e4 LT |
23 | #define LIST_HEAD_INIT(name) { &(name), &(name) } |
24 | ||
25 | #define LIST_HEAD(name) \ | |
26 | struct list_head name = LIST_HEAD_INIT(name) | |
27 | ||
46deb744 PM |
28 | /** |
29 | * INIT_LIST_HEAD - Initialize a list_head structure | |
30 | * @list: list_head structure to be initialized. | |
31 | * | |
32 | * Initializes the list_head to point to itself. If it is a list header, | |
33 | * the result is an empty list. | |
34 | */ | |
490d6ab1 ZB |
35 | static inline void INIT_LIST_HEAD(struct list_head *list) |
36 | { | |
2f073848 | 37 | WRITE_ONCE(list->next, list); |
490d6ab1 ZB |
38 | list->prev = list; |
39 | } | |
1da177e4 | 40 | |
d7c81673 KC |
41 | #ifdef CONFIG_DEBUG_LIST |
42 | extern bool __list_add_valid(struct list_head *new, | |
43 | struct list_head *prev, | |
44 | struct list_head *next); | |
0cd340dc | 45 | extern bool __list_del_entry_valid(struct list_head *entry); |
d7c81673 KC |
46 | #else |
47 | static inline bool __list_add_valid(struct list_head *new, | |
48 | struct list_head *prev, | |
49 | struct list_head *next) | |
50 | { | |
51 | return true; | |
52 | } | |
0cd340dc KC |
53 | static inline bool __list_del_entry_valid(struct list_head *entry) |
54 | { | |
55 | return true; | |
56 | } | |
d7c81673 KC |
57 | #endif |
58 | ||
1da177e4 LT |
59 | /* |
60 | * Insert a new entry between two known consecutive entries. | |
61 | * | |
62 | * This is only for internal list manipulation where we know | |
63 | * the prev/next entries already! | |
64 | */ | |
65 | static inline void __list_add(struct list_head *new, | |
66 | struct list_head *prev, | |
67 | struct list_head *next) | |
68 | { | |
d7c81673 KC |
69 | if (!__list_add_valid(new, prev, next)) |
70 | return; | |
71 | ||
1da177e4 LT |
72 | next->prev = new; |
73 | new->next = next; | |
74 | new->prev = prev; | |
1c97be67 | 75 | WRITE_ONCE(prev->next, new); |
1da177e4 LT |
76 | } |
77 | ||
78 | /** | |
79 | * list_add - add a new entry | |
80 | * @new: new entry to be added | |
81 | * @head: list head to add it after | |
82 | * | |
83 | * Insert a new entry after the specified head. | |
84 | * This is good for implementing stacks. | |
85 | */ | |
86 | static inline void list_add(struct list_head *new, struct list_head *head) | |
87 | { | |
88 | __list_add(new, head, head->next); | |
89 | } | |
199a9afc | 90 | |
1da177e4 LT |
91 | |
92 | /** | |
93 | * list_add_tail - add a new entry | |
94 | * @new: new entry to be added | |
95 | * @head: list head to add it before | |
96 | * | |
97 | * Insert a new entry before the specified head. | |
98 | * This is useful for implementing queues. | |
99 | */ | |
100 | static inline void list_add_tail(struct list_head *new, struct list_head *head) | |
101 | { | |
102 | __list_add(new, head->prev, head); | |
103 | } | |
104 | ||
1da177e4 LT |
105 | /* |
106 | * Delete a list entry by making the prev/next entries | |
107 | * point to each other. | |
108 | * | |
109 | * This is only for internal list manipulation where we know | |
110 | * the prev/next entries already! | |
111 | */ | |
112 | static inline void __list_del(struct list_head * prev, struct list_head * next) | |
113 | { | |
114 | next->prev = prev; | |
7f5f873c | 115 | WRITE_ONCE(prev->next, next); |
1da177e4 LT |
116 | } |
117 | ||
c8af5cd7 THJ |
118 | /* |
119 | * Delete a list entry and clear the 'prev' pointer. | |
120 | * | |
121 | * This is a special-purpose list clearing method used in the networking code | |
122 | * for lists allocated as per-cpu, where we don't want to incur the extra | |
123 | * WRITE_ONCE() overhead of a regular list_del_init(). The code that uses this | |
124 | * needs to check the node 'prev' pointer instead of calling list_empty(). | |
125 | */ | |
126 | static inline void __list_del_clearprev(struct list_head *entry) | |
127 | { | |
128 | __list_del(entry->prev, entry->next); | |
129 | entry->prev = NULL; | |
130 | } | |
131 | ||
3c18d4de LT |
132 | static inline void __list_del_entry(struct list_head *entry) |
133 | { | |
0cd340dc KC |
134 | if (!__list_del_entry_valid(entry)) |
135 | return; | |
136 | ||
3c18d4de LT |
137 | __list_del(entry->prev, entry->next); |
138 | } | |
139 | ||
46deb744 PM |
140 | /** |
141 | * list_del - deletes entry from list. | |
142 | * @entry: the element to delete from the list. | |
143 | * Note: list_empty() on entry does not return true after this, the entry is | |
144 | * in an undefined state. | |
145 | */ | |
1da177e4 LT |
146 | static inline void list_del(struct list_head *entry) |
147 | { | |
0cd340dc | 148 | __list_del_entry(entry); |
1da177e4 LT |
149 | entry->next = LIST_POISON1; |
150 | entry->prev = LIST_POISON2; | |
151 | } | |
152 | ||
54e73770 ON |
153 | /** |
154 | * list_replace - replace old entry by new one | |
155 | * @old : the element to be replaced | |
156 | * @new : the new element to insert | |
72fd4a35 RD |
157 | * |
158 | * If @old was empty, it will be overwritten. | |
54e73770 ON |
159 | */ |
160 | static inline void list_replace(struct list_head *old, | |
161 | struct list_head *new) | |
162 | { | |
163 | new->next = old->next; | |
164 | new->next->prev = new; | |
165 | new->prev = old->prev; | |
166 | new->prev->next = new; | |
167 | } | |
168 | ||
46deb744 PM |
169 | /** |
170 | * list_replace_init - replace old entry by new one and initialize the old one | |
171 | * @old : the element to be replaced | |
172 | * @new : the new element to insert | |
173 | * | |
174 | * If @old was empty, it will be overwritten. | |
175 | */ | |
54e73770 | 176 | static inline void list_replace_init(struct list_head *old, |
46deb744 | 177 | struct list_head *new) |
54e73770 ON |
178 | { |
179 | list_replace(old, new); | |
180 | INIT_LIST_HEAD(old); | |
181 | } | |
182 | ||
e900a918 DW |
183 | /** |
184 | * list_swap - replace entry1 with entry2 and re-add entry1 at entry2's position | |
185 | * @entry1: the location to place entry2 | |
186 | * @entry2: the location to place entry1 | |
187 | */ | |
188 | static inline void list_swap(struct list_head *entry1, | |
189 | struct list_head *entry2) | |
190 | { | |
191 | struct list_head *pos = entry2->prev; | |
192 | ||
193 | list_del(entry2); | |
194 | list_replace(entry1, entry2); | |
195 | if (pos == entry1) | |
196 | pos = entry2; | |
197 | list_add(entry1, pos); | |
198 | } | |
199 | ||
1da177e4 LT |
200 | /** |
201 | * list_del_init - deletes entry from list and reinitialize it. | |
202 | * @entry: the element to delete from the list. | |
203 | */ | |
204 | static inline void list_del_init(struct list_head *entry) | |
205 | { | |
3c18d4de | 206 | __list_del_entry(entry); |
1da177e4 LT |
207 | INIT_LIST_HEAD(entry); |
208 | } | |
209 | ||
210 | /** | |
211 | * list_move - delete from one list and add as another's head | |
212 | * @list: the entry to move | |
213 | * @head: the head that will precede our entry | |
214 | */ | |
215 | static inline void list_move(struct list_head *list, struct list_head *head) | |
216 | { | |
3c18d4de | 217 | __list_del_entry(list); |
78db2ad6 | 218 | list_add(list, head); |
1da177e4 LT |
219 | } |
220 | ||
221 | /** | |
222 | * list_move_tail - delete from one list and add as another's tail | |
223 | * @list: the entry to move | |
224 | * @head: the head that will follow our entry | |
225 | */ | |
226 | static inline void list_move_tail(struct list_head *list, | |
227 | struct list_head *head) | |
228 | { | |
3c18d4de | 229 | __list_del_entry(list); |
78db2ad6 | 230 | list_add_tail(list, head); |
1da177e4 LT |
231 | } |
232 | ||
df2fc43d CK |
233 | /** |
234 | * list_bulk_move_tail - move a subsection of a list to its tail | |
235 | * @head: the head that will follow our entry | |
236 | * @first: first entry to move | |
237 | * @last: last entry to move, can be the same as first | |
238 | * | |
239 | * Move all entries between @first and including @last before @head. | |
240 | * All three entries must belong to the same linked list. | |
241 | */ | |
242 | static inline void list_bulk_move_tail(struct list_head *head, | |
243 | struct list_head *first, | |
244 | struct list_head *last) | |
245 | { | |
246 | first->prev->next = last->next; | |
247 | last->next->prev = first->prev; | |
248 | ||
249 | head->prev->next = first; | |
250 | first->prev = head->prev; | |
251 | ||
252 | last->next = head; | |
253 | head->prev = last; | |
254 | } | |
255 | ||
70b44595 | 256 | /** |
b736523f | 257 | * list_is_first -- tests whether @list is the first entry in list @head |
70b44595 MG |
258 | * @list: the entry to test |
259 | * @head: the head of the list | |
260 | */ | |
04254730 | 261 | static inline int list_is_first(const struct list_head *list, const struct list_head *head) |
70b44595 MG |
262 | { |
263 | return list->prev == head; | |
264 | } | |
265 | ||
e8f4d97e SN |
266 | /** |
267 | * list_is_last - tests whether @list is the last entry in list @head | |
268 | * @list: the entry to test | |
269 | * @head: the head of the list | |
270 | */ | |
04254730 | 271 | static inline int list_is_last(const struct list_head *list, const struct list_head *head) |
e8f4d97e SN |
272 | { |
273 | return list->next == head; | |
274 | } | |
275 | ||
04254730 AS |
276 | /** |
277 | * list_is_head - tests whether @list is the list @head | |
278 | * @list: the entry to test | |
279 | * @head: the head of the list | |
280 | */ | |
281 | static inline int list_is_head(const struct list_head *list, const struct list_head *head) | |
282 | { | |
283 | return list == head; | |
284 | } | |
285 | ||
1da177e4 LT |
286 | /** |
287 | * list_empty - tests whether a list is empty | |
288 | * @head: the list to test. | |
289 | */ | |
290 | static inline int list_empty(const struct list_head *head) | |
291 | { | |
1658d35e | 292 | return READ_ONCE(head->next) == head; |
1da177e4 LT |
293 | } |
294 | ||
c6fe44d9 LT |
295 | /** |
296 | * list_del_init_careful - deletes entry from list and reinitialize it. | |
297 | * @entry: the element to delete from the list. | |
298 | * | |
299 | * This is the same as list_del_init(), except designed to be used | |
300 | * together with list_empty_careful() in a way to guarantee ordering | |
301 | * of other memory operations. | |
302 | * | |
303 | * Any memory operations done before a list_del_init_careful() are | |
304 | * guaranteed to be visible after a list_empty_careful() test. | |
305 | */ | |
306 | static inline void list_del_init_careful(struct list_head *entry) | |
307 | { | |
308 | __list_del_entry(entry); | |
309 | entry->prev = entry; | |
310 | smp_store_release(&entry->next, entry); | |
311 | } | |
312 | ||
1da177e4 | 313 | /** |
fe96e57d RD |
314 | * list_empty_careful - tests whether a list is empty and not being modified |
315 | * @head: the list to test | |
316 | * | |
317 | * Description: | |
318 | * tests whether a list is empty _and_ checks that no other CPU might be | |
319 | * in the process of modifying either member (next or prev) | |
1da177e4 LT |
320 | * |
321 | * NOTE: using list_empty_careful() without synchronization | |
322 | * can only be safe if the only activity that can happen | |
323 | * to the list entry is list_del_init(). Eg. it cannot be used | |
324 | * if another CPU could re-list_add() it. | |
1da177e4 LT |
325 | */ |
326 | static inline int list_empty_careful(const struct list_head *head) | |
327 | { | |
c6fe44d9 | 328 | struct list_head *next = smp_load_acquire(&head->next); |
04254730 | 329 | return list_is_head(next, head) && (next == head->prev); |
99602572 MH |
330 | } |
331 | ||
5908cdc8 FW |
332 | /** |
333 | * list_rotate_left - rotate the list to the left | |
334 | * @head: the head of the list | |
335 | */ | |
336 | static inline void list_rotate_left(struct list_head *head) | |
337 | { | |
338 | struct list_head *first; | |
339 | ||
340 | if (!list_empty(head)) { | |
341 | first = head->next; | |
342 | list_move_tail(first, head); | |
343 | } | |
344 | } | |
345 | ||
a16b5384 TH |
346 | /** |
347 | * list_rotate_to_front() - Rotate list to specific item. | |
348 | * @list: The desired new front of the list. | |
349 | * @head: The head of the list. | |
350 | * | |
351 | * Rotates list so that @list becomes the new front of the list. | |
352 | */ | |
353 | static inline void list_rotate_to_front(struct list_head *list, | |
354 | struct list_head *head) | |
355 | { | |
356 | /* | |
357 | * Deletes the list head from the list denoted by @head and | |
358 | * places it as the tail of @list, this effectively rotates the | |
359 | * list so that @list is at the front. | |
360 | */ | |
361 | list_move_tail(head, list); | |
362 | } | |
363 | ||
99602572 MH |
364 | /** |
365 | * list_is_singular - tests whether a list has just one entry. | |
366 | * @head: the list to test. | |
367 | */ | |
368 | static inline int list_is_singular(const struct list_head *head) | |
369 | { | |
370 | return !list_empty(head) && (head->next == head->prev); | |
1da177e4 LT |
371 | } |
372 | ||
00e8a4da LR |
373 | static inline void __list_cut_position(struct list_head *list, |
374 | struct list_head *head, struct list_head *entry) | |
375 | { | |
376 | struct list_head *new_first = entry->next; | |
377 | list->next = head->next; | |
378 | list->next->prev = list; | |
379 | list->prev = entry; | |
380 | entry->next = list; | |
381 | head->next = new_first; | |
382 | new_first->prev = head; | |
383 | } | |
384 | ||
385 | /** | |
386 | * list_cut_position - cut a list into two | |
387 | * @list: a new list to add all removed entries | |
388 | * @head: a list with entries | |
389 | * @entry: an entry within head, could be the head itself | |
390 | * and if so we won't cut the list | |
391 | * | |
392 | * This helper moves the initial part of @head, up to and | |
393 | * including @entry, from @head to @list. You should | |
394 | * pass on @entry an element you know is on @head. @list | |
395 | * should be an empty list or a list you do not care about | |
396 | * losing its data. | |
397 | * | |
398 | */ | |
399 | static inline void list_cut_position(struct list_head *list, | |
400 | struct list_head *head, struct list_head *entry) | |
401 | { | |
402 | if (list_empty(head)) | |
403 | return; | |
04254730 | 404 | if (list_is_singular(head) && !list_is_head(entry, head) && (entry != head->next)) |
00e8a4da | 405 | return; |
04254730 | 406 | if (list_is_head(entry, head)) |
00e8a4da LR |
407 | INIT_LIST_HEAD(list); |
408 | else | |
409 | __list_cut_position(list, head, entry); | |
410 | } | |
411 | ||
4ce0017a EC |
412 | /** |
413 | * list_cut_before - cut a list into two, before given entry | |
414 | * @list: a new list to add all removed entries | |
415 | * @head: a list with entries | |
416 | * @entry: an entry within head, could be the head itself | |
417 | * | |
418 | * This helper moves the initial part of @head, up to but | |
419 | * excluding @entry, from @head to @list. You should pass | |
420 | * in @entry an element you know is on @head. @list should | |
421 | * be an empty list or a list you do not care about losing | |
422 | * its data. | |
423 | * If @entry == @head, all entries on @head are moved to | |
424 | * @list. | |
425 | */ | |
426 | static inline void list_cut_before(struct list_head *list, | |
427 | struct list_head *head, | |
428 | struct list_head *entry) | |
429 | { | |
430 | if (head->next == entry) { | |
431 | INIT_LIST_HEAD(list); | |
432 | return; | |
433 | } | |
434 | list->next = head->next; | |
435 | list->next->prev = list; | |
436 | list->prev = entry->prev; | |
437 | list->prev->next = list; | |
438 | head->next = entry; | |
439 | entry->prev = head; | |
440 | } | |
441 | ||
95d8c365 | 442 | static inline void __list_splice(const struct list_head *list, |
7d283aee LR |
443 | struct list_head *prev, |
444 | struct list_head *next) | |
1da177e4 LT |
445 | { |
446 | struct list_head *first = list->next; | |
447 | struct list_head *last = list->prev; | |
1da177e4 | 448 | |
7d283aee LR |
449 | first->prev = prev; |
450 | prev->next = first; | |
1da177e4 | 451 | |
7d283aee LR |
452 | last->next = next; |
453 | next->prev = last; | |
1da177e4 LT |
454 | } |
455 | ||
456 | /** | |
7d283aee | 457 | * list_splice - join two lists, this is designed for stacks |
1da177e4 LT |
458 | * @list: the new list to add. |
459 | * @head: the place to add it in the first list. | |
460 | */ | |
95d8c365 RD |
461 | static inline void list_splice(const struct list_head *list, |
462 | struct list_head *head) | |
1da177e4 LT |
463 | { |
464 | if (!list_empty(list)) | |
7d283aee LR |
465 | __list_splice(list, head, head->next); |
466 | } | |
467 | ||
468 | /** | |
469 | * list_splice_tail - join two lists, each list being a queue | |
470 | * @list: the new list to add. | |
471 | * @head: the place to add it in the first list. | |
472 | */ | |
473 | static inline void list_splice_tail(struct list_head *list, | |
474 | struct list_head *head) | |
475 | { | |
476 | if (!list_empty(list)) | |
477 | __list_splice(list, head->prev, head); | |
1da177e4 LT |
478 | } |
479 | ||
480 | /** | |
481 | * list_splice_init - join two lists and reinitialise the emptied list. | |
482 | * @list: the new list to add. | |
483 | * @head: the place to add it in the first list. | |
484 | * | |
485 | * The list at @list is reinitialised | |
486 | */ | |
487 | static inline void list_splice_init(struct list_head *list, | |
488 | struct list_head *head) | |
489 | { | |
490 | if (!list_empty(list)) { | |
7d283aee LR |
491 | __list_splice(list, head, head->next); |
492 | INIT_LIST_HEAD(list); | |
493 | } | |
494 | } | |
495 | ||
496 | /** | |
6724cce8 | 497 | * list_splice_tail_init - join two lists and reinitialise the emptied list |
7d283aee LR |
498 | * @list: the new list to add. |
499 | * @head: the place to add it in the first list. | |
500 | * | |
6724cce8 | 501 | * Each of the lists is a queue. |
7d283aee LR |
502 | * The list at @list is reinitialised |
503 | */ | |
504 | static inline void list_splice_tail_init(struct list_head *list, | |
505 | struct list_head *head) | |
506 | { | |
507 | if (!list_empty(list)) { | |
508 | __list_splice(list, head->prev, head); | |
1da177e4 LT |
509 | INIT_LIST_HEAD(list); |
510 | } | |
511 | } | |
512 | ||
513 | /** | |
514 | * list_entry - get the struct for this entry | |
515 | * @ptr: the &struct list_head pointer. | |
516 | * @type: the type of the struct this is embedded in. | |
3943f42c | 517 | * @member: the name of the list_head within the struct. |
1da177e4 LT |
518 | */ |
519 | #define list_entry(ptr, type, member) \ | |
520 | container_of(ptr, type, member) | |
521 | ||
b5e61818 PE |
522 | /** |
523 | * list_first_entry - get the first element from a list | |
524 | * @ptr: the list head to take the element from. | |
525 | * @type: the type of the struct this is embedded in. | |
3943f42c | 526 | * @member: the name of the list_head within the struct. |
b5e61818 PE |
527 | * |
528 | * Note, that list is expected to be not empty. | |
529 | */ | |
530 | #define list_first_entry(ptr, type, member) \ | |
531 | list_entry((ptr)->next, type, member) | |
532 | ||
93be3c2e ON |
533 | /** |
534 | * list_last_entry - get the last element from a list | |
535 | * @ptr: the list head to take the element from. | |
536 | * @type: the type of the struct this is embedded in. | |
3943f42c | 537 | * @member: the name of the list_head within the struct. |
93be3c2e ON |
538 | * |
539 | * Note, that list is expected to be not empty. | |
540 | */ | |
541 | #define list_last_entry(ptr, type, member) \ | |
542 | list_entry((ptr)->prev, type, member) | |
543 | ||
6d7581e6 JP |
544 | /** |
545 | * list_first_entry_or_null - get the first element from a list | |
546 | * @ptr: the list head to take the element from. | |
547 | * @type: the type of the struct this is embedded in. | |
3943f42c | 548 | * @member: the name of the list_head within the struct. |
6d7581e6 JP |
549 | * |
550 | * Note that if the list is empty, it returns NULL. | |
551 | */ | |
12adfd88 CW |
552 | #define list_first_entry_or_null(ptr, type, member) ({ \ |
553 | struct list_head *head__ = (ptr); \ | |
554 | struct list_head *pos__ = READ_ONCE(head__->next); \ | |
555 | pos__ != head__ ? list_entry(pos__, type, member) : NULL; \ | |
556 | }) | |
6d7581e6 | 557 | |
008208c6 ON |
558 | /** |
559 | * list_next_entry - get the next element in list | |
560 | * @pos: the type * to cursor | |
3943f42c | 561 | * @member: the name of the list_head within the struct. |
008208c6 ON |
562 | */ |
563 | #define list_next_entry(pos, member) \ | |
564 | list_entry((pos)->member.next, typeof(*(pos)), member) | |
565 | ||
566 | /** | |
567 | * list_prev_entry - get the prev element in list | |
568 | * @pos: the type * to cursor | |
3943f42c | 569 | * @member: the name of the list_head within the struct. |
008208c6 ON |
570 | */ |
571 | #define list_prev_entry(pos, member) \ | |
572 | list_entry((pos)->member.prev, typeof(*(pos)), member) | |
573 | ||
1da177e4 LT |
574 | /** |
575 | * list_for_each - iterate over a list | |
8e3a67a9 | 576 | * @pos: the &struct list_head to use as a loop cursor. |
1da177e4 LT |
577 | * @head: the head for your list. |
578 | */ | |
579 | #define list_for_each(pos, head) \ | |
04254730 | 580 | for (pos = (head)->next; !list_is_head(pos, (head)); pos = pos->next) |
1da177e4 | 581 | |
28ca0d6d PB |
582 | /** |
583 | * list_for_each_continue - continue iteration over a list | |
584 | * @pos: the &struct list_head to use as a loop cursor. | |
585 | * @head: the head for your list. | |
586 | * | |
587 | * Continue to iterate over a list, continuing after the current position. | |
588 | */ | |
589 | #define list_for_each_continue(pos, head) \ | |
04254730 | 590 | for (pos = pos->next; !list_is_head(pos, (head)); pos = pos->next) |
28ca0d6d | 591 | |
1da177e4 LT |
592 | /** |
593 | * list_for_each_prev - iterate over a list backwards | |
8e3a67a9 | 594 | * @pos: the &struct list_head to use as a loop cursor. |
1da177e4 LT |
595 | * @head: the head for your list. |
596 | */ | |
597 | #define list_for_each_prev(pos, head) \ | |
04254730 | 598 | for (pos = (head)->prev; !list_is_head(pos, (head)); pos = pos->prev) |
1da177e4 LT |
599 | |
600 | /** | |
fe96e57d | 601 | * list_for_each_safe - iterate over a list safe against removal of list entry |
8e3a67a9 | 602 | * @pos: the &struct list_head to use as a loop cursor. |
1da177e4 LT |
603 | * @n: another &struct list_head to use as temporary storage |
604 | * @head: the head for your list. | |
605 | */ | |
606 | #define list_for_each_safe(pos, n, head) \ | |
04254730 AS |
607 | for (pos = (head)->next, n = pos->next; \ |
608 | !list_is_head(pos, (head)); \ | |
609 | pos = n, n = pos->next) | |
1da177e4 | 610 | |
37c42524 | 611 | /** |
8f731f7d | 612 | * list_for_each_prev_safe - iterate over a list backwards safe against removal of list entry |
37c42524 DL |
613 | * @pos: the &struct list_head to use as a loop cursor. |
614 | * @n: another &struct list_head to use as temporary storage | |
615 | * @head: the head for your list. | |
616 | */ | |
617 | #define list_for_each_prev_safe(pos, n, head) \ | |
618 | for (pos = (head)->prev, n = pos->prev; \ | |
04254730 | 619 | !list_is_head(pos, (head)); \ |
37c42524 DL |
620 | pos = n, n = pos->prev) |
621 | ||
e1308161 AS |
622 | /** |
623 | * list_entry_is_head - test if the entry points to the head of the list | |
624 | * @pos: the type * to cursor | |
625 | * @head: the head for your list. | |
626 | * @member: the name of the list_head within the struct. | |
627 | */ | |
628 | #define list_entry_is_head(pos, head, member) \ | |
629 | (&pos->member == (head)) | |
630 | ||
1da177e4 LT |
631 | /** |
632 | * list_for_each_entry - iterate over list of given type | |
8e3a67a9 | 633 | * @pos: the type * to use as a loop cursor. |
1da177e4 | 634 | * @head: the head for your list. |
3943f42c | 635 | * @member: the name of the list_head within the struct. |
1da177e4 LT |
636 | */ |
637 | #define list_for_each_entry(pos, head, member) \ | |
93be3c2e | 638 | for (pos = list_first_entry(head, typeof(*pos), member); \ |
e1308161 | 639 | !list_entry_is_head(pos, head, member); \ |
8120e2e5 | 640 | pos = list_next_entry(pos, member)) |
1da177e4 LT |
641 | |
642 | /** | |
643 | * list_for_each_entry_reverse - iterate backwards over list of given type. | |
8e3a67a9 | 644 | * @pos: the type * to use as a loop cursor. |
1da177e4 | 645 | * @head: the head for your list. |
3943f42c | 646 | * @member: the name of the list_head within the struct. |
1da177e4 LT |
647 | */ |
648 | #define list_for_each_entry_reverse(pos, head, member) \ | |
93be3c2e | 649 | for (pos = list_last_entry(head, typeof(*pos), member); \ |
e1308161 | 650 | !list_entry_is_head(pos, head, member); \ |
8120e2e5 | 651 | pos = list_prev_entry(pos, member)) |
1da177e4 LT |
652 | |
653 | /** | |
72fd4a35 | 654 | * list_prepare_entry - prepare a pos entry for use in list_for_each_entry_continue() |
1da177e4 LT |
655 | * @pos: the type * to use as a start point |
656 | * @head: the head of the list | |
3943f42c | 657 | * @member: the name of the list_head within the struct. |
fe96e57d | 658 | * |
72fd4a35 | 659 | * Prepares a pos entry for use as a start point in list_for_each_entry_continue(). |
1da177e4 LT |
660 | */ |
661 | #define list_prepare_entry(pos, head, member) \ | |
662 | ((pos) ? : list_entry(head, typeof(*pos), member)) | |
663 | ||
664 | /** | |
fe96e57d | 665 | * list_for_each_entry_continue - continue iteration over list of given type |
8e3a67a9 | 666 | * @pos: the type * to use as a loop cursor. |
1da177e4 | 667 | * @head: the head for your list. |
3943f42c | 668 | * @member: the name of the list_head within the struct. |
fe96e57d RD |
669 | * |
670 | * Continue to iterate over list of given type, continuing after | |
671 | * the current position. | |
1da177e4 LT |
672 | */ |
673 | #define list_for_each_entry_continue(pos, head, member) \ | |
8120e2e5 | 674 | for (pos = list_next_entry(pos, member); \ |
e1308161 | 675 | !list_entry_is_head(pos, head, member); \ |
8120e2e5 | 676 | pos = list_next_entry(pos, member)) |
1da177e4 | 677 | |
768f3591 PE |
678 | /** |
679 | * list_for_each_entry_continue_reverse - iterate backwards from the given point | |
680 | * @pos: the type * to use as a loop cursor. | |
681 | * @head: the head for your list. | |
3943f42c | 682 | * @member: the name of the list_head within the struct. |
768f3591 PE |
683 | * |
684 | * Start to iterate over list of given type backwards, continuing after | |
685 | * the current position. | |
686 | */ | |
687 | #define list_for_each_entry_continue_reverse(pos, head, member) \ | |
8120e2e5 | 688 | for (pos = list_prev_entry(pos, member); \ |
e1308161 | 689 | !list_entry_is_head(pos, head, member); \ |
8120e2e5 | 690 | pos = list_prev_entry(pos, member)) |
768f3591 | 691 | |
e229c2fb | 692 | /** |
fe96e57d | 693 | * list_for_each_entry_from - iterate over list of given type from the current point |
8e3a67a9 | 694 | * @pos: the type * to use as a loop cursor. |
e229c2fb | 695 | * @head: the head for your list. |
3943f42c | 696 | * @member: the name of the list_head within the struct. |
fe96e57d RD |
697 | * |
698 | * Iterate over list of given type, continuing from current position. | |
e229c2fb ACM |
699 | */ |
700 | #define list_for_each_entry_from(pos, head, member) \ | |
e1308161 | 701 | for (; !list_entry_is_head(pos, head, member); \ |
8120e2e5 | 702 | pos = list_next_entry(pos, member)) |
e229c2fb | 703 | |
b862815c JP |
704 | /** |
705 | * list_for_each_entry_from_reverse - iterate backwards over list of given type | |
706 | * from the current point | |
707 | * @pos: the type * to use as a loop cursor. | |
708 | * @head: the head for your list. | |
709 | * @member: the name of the list_head within the struct. | |
710 | * | |
711 | * Iterate backwards over list of given type, continuing from current position. | |
712 | */ | |
713 | #define list_for_each_entry_from_reverse(pos, head, member) \ | |
e1308161 | 714 | for (; !list_entry_is_head(pos, head, member); \ |
b862815c JP |
715 | pos = list_prev_entry(pos, member)) |
716 | ||
1da177e4 LT |
717 | /** |
718 | * list_for_each_entry_safe - iterate over list of given type safe against removal of list entry | |
8e3a67a9 | 719 | * @pos: the type * to use as a loop cursor. |
1da177e4 LT |
720 | * @n: another type * to use as temporary storage |
721 | * @head: the head for your list. | |
3943f42c | 722 | * @member: the name of the list_head within the struct. |
1da177e4 LT |
723 | */ |
724 | #define list_for_each_entry_safe(pos, n, head, member) \ | |
93be3c2e | 725 | for (pos = list_first_entry(head, typeof(*pos), member), \ |
8120e2e5 | 726 | n = list_next_entry(pos, member); \ |
e1308161 | 727 | !list_entry_is_head(pos, head, member); \ |
8120e2e5 | 728 | pos = n, n = list_next_entry(n, member)) |
1da177e4 | 729 | |
74459dc7 | 730 | /** |
9a86e2ba | 731 | * list_for_each_entry_safe_continue - continue list iteration safe against removal |
8e3a67a9 | 732 | * @pos: the type * to use as a loop cursor. |
74459dc7 ACM |
733 | * @n: another type * to use as temporary storage |
734 | * @head: the head for your list. | |
3943f42c | 735 | * @member: the name of the list_head within the struct. |
fe96e57d RD |
736 | * |
737 | * Iterate over list of given type, continuing after current point, | |
738 | * safe against removal of list entry. | |
74459dc7 ACM |
739 | */ |
740 | #define list_for_each_entry_safe_continue(pos, n, head, member) \ | |
8120e2e5 ON |
741 | for (pos = list_next_entry(pos, member), \ |
742 | n = list_next_entry(pos, member); \ | |
e1308161 | 743 | !list_entry_is_head(pos, head, member); \ |
8120e2e5 | 744 | pos = n, n = list_next_entry(n, member)) |
d8dcffee ACM |
745 | |
746 | /** | |
9a86e2ba | 747 | * list_for_each_entry_safe_from - iterate over list from current point safe against removal |
8e3a67a9 | 748 | * @pos: the type * to use as a loop cursor. |
d8dcffee ACM |
749 | * @n: another type * to use as temporary storage |
750 | * @head: the head for your list. | |
3943f42c | 751 | * @member: the name of the list_head within the struct. |
fe96e57d RD |
752 | * |
753 | * Iterate over list of given type from current point, safe against | |
754 | * removal of list entry. | |
d8dcffee ACM |
755 | */ |
756 | #define list_for_each_entry_safe_from(pos, n, head, member) \ | |
8120e2e5 | 757 | for (n = list_next_entry(pos, member); \ |
e1308161 | 758 | !list_entry_is_head(pos, head, member); \ |
8120e2e5 | 759 | pos = n, n = list_next_entry(n, member)) |
74459dc7 | 760 | |
0ad42352 | 761 | /** |
9a86e2ba | 762 | * list_for_each_entry_safe_reverse - iterate backwards over list safe against removal |
8e3a67a9 | 763 | * @pos: the type * to use as a loop cursor. |
0ad42352 DH |
764 | * @n: another type * to use as temporary storage |
765 | * @head: the head for your list. | |
3943f42c | 766 | * @member: the name of the list_head within the struct. |
fe96e57d RD |
767 | * |
768 | * Iterate backwards over list of given type, safe against removal | |
769 | * of list entry. | |
0ad42352 DH |
770 | */ |
771 | #define list_for_each_entry_safe_reverse(pos, n, head, member) \ | |
93be3c2e | 772 | for (pos = list_last_entry(head, typeof(*pos), member), \ |
8120e2e5 | 773 | n = list_prev_entry(pos, member); \ |
e1308161 | 774 | !list_entry_is_head(pos, head, member); \ |
8120e2e5 | 775 | pos = n, n = list_prev_entry(n, member)) |
0ad42352 | 776 | |
57439f87 | 777 | /** |
778 | * list_safe_reset_next - reset a stale list_for_each_entry_safe loop | |
779 | * @pos: the loop cursor used in the list_for_each_entry_safe loop | |
780 | * @n: temporary storage used in list_for_each_entry_safe | |
3943f42c | 781 | * @member: the name of the list_head within the struct. |
57439f87 | 782 | * |
783 | * list_safe_reset_next is not safe to use in general if the list may be | |
784 | * modified concurrently (eg. the lock is dropped in the loop body). An | |
785 | * exception to this is if the cursor element (pos) is pinned in the list, | |
786 | * and list_safe_reset_next is called after re-taking the lock and before | |
787 | * completing the current iteration of the loop body. | |
788 | */ | |
789 | #define list_safe_reset_next(pos, n, member) \ | |
8120e2e5 | 790 | n = list_next_entry(pos, member) |
57439f87 | 791 | |
1da177e4 LT |
792 | /* |
793 | * Double linked lists with a single pointer list head. | |
794 | * Mostly useful for hash tables where the two pointer list head is | |
795 | * too wasteful. | |
796 | * You lose the ability to access the tail in O(1). | |
797 | */ | |
798 | ||
1da177e4 LT |
799 | #define HLIST_HEAD_INIT { .first = NULL } |
800 | #define HLIST_HEAD(name) struct hlist_head name = { .first = NULL } | |
801 | #define INIT_HLIST_HEAD(ptr) ((ptr)->first = NULL) | |
490d6ab1 ZB |
802 | static inline void INIT_HLIST_NODE(struct hlist_node *h) |
803 | { | |
804 | h->next = NULL; | |
805 | h->pprev = NULL; | |
806 | } | |
1da177e4 | 807 | |
46deb744 PM |
808 | /** |
809 | * hlist_unhashed - Has node been removed from list and reinitialized? | |
810 | * @h: Node to be checked | |
811 | * | |
812 | * Not that not all removal functions will leave a node in unhashed | |
813 | * state. For example, hlist_nulls_del_init_rcu() does leave the | |
814 | * node in unhashed state, but hlist_nulls_del() does not. | |
815 | */ | |
1da177e4 LT |
816 | static inline int hlist_unhashed(const struct hlist_node *h) |
817 | { | |
818 | return !h->pprev; | |
819 | } | |
820 | ||
46deb744 PM |
821 | /** |
822 | * hlist_unhashed_lockless - Version of hlist_unhashed for lockless use | |
823 | * @h: Node to be checked | |
824 | * | |
825 | * This variant of hlist_unhashed() must be used in lockless contexts | |
826 | * to avoid potential load-tearing. The READ_ONCE() is paired with the | |
827 | * various WRITE_ONCE() in hlist helpers that are defined below. | |
c54a2744 ED |
828 | */ |
829 | static inline int hlist_unhashed_lockless(const struct hlist_node *h) | |
830 | { | |
831 | return !READ_ONCE(h->pprev); | |
832 | } | |
833 | ||
46deb744 PM |
834 | /** |
835 | * hlist_empty - Is the specified hlist_head structure an empty hlist? | |
836 | * @h: Structure to check. | |
837 | */ | |
1da177e4 LT |
838 | static inline int hlist_empty(const struct hlist_head *h) |
839 | { | |
1658d35e | 840 | return !READ_ONCE(h->first); |
1da177e4 LT |
841 | } |
842 | ||
843 | static inline void __hlist_del(struct hlist_node *n) | |
844 | { | |
845 | struct hlist_node *next = n->next; | |
846 | struct hlist_node **pprev = n->pprev; | |
7f5f873c PM |
847 | |
848 | WRITE_ONCE(*pprev, next); | |
1da177e4 | 849 | if (next) |
c54a2744 | 850 | WRITE_ONCE(next->pprev, pprev); |
1da177e4 LT |
851 | } |
852 | ||
46deb744 PM |
853 | /** |
854 | * hlist_del - Delete the specified hlist_node from its list | |
855 | * @n: Node to delete. | |
856 | * | |
857 | * Note that this function leaves the node in hashed state. Use | |
858 | * hlist_del_init() or similar instead to unhash @n. | |
859 | */ | |
1da177e4 LT |
860 | static inline void hlist_del(struct hlist_node *n) |
861 | { | |
862 | __hlist_del(n); | |
863 | n->next = LIST_POISON1; | |
864 | n->pprev = LIST_POISON2; | |
865 | } | |
866 | ||
46deb744 PM |
867 | /** |
868 | * hlist_del_init - Delete the specified hlist_node from its list and initialize | |
869 | * @n: Node to delete. | |
870 | * | |
871 | * Note that this function leaves the node in unhashed state. | |
872 | */ | |
1da177e4 LT |
873 | static inline void hlist_del_init(struct hlist_node *n) |
874 | { | |
da753bea | 875 | if (!hlist_unhashed(n)) { |
1da177e4 LT |
876 | __hlist_del(n); |
877 | INIT_HLIST_NODE(n); | |
878 | } | |
879 | } | |
880 | ||
46deb744 PM |
881 | /** |
882 | * hlist_add_head - add a new entry at the beginning of the hlist | |
883 | * @n: new entry to be added | |
884 | * @h: hlist head to add it after | |
885 | * | |
886 | * Insert a new entry after the specified head. | |
887 | * This is good for implementing stacks. | |
888 | */ | |
1da177e4 LT |
889 | static inline void hlist_add_head(struct hlist_node *n, struct hlist_head *h) |
890 | { | |
891 | struct hlist_node *first = h->first; | |
c54a2744 | 892 | WRITE_ONCE(n->next, first); |
1da177e4 | 893 | if (first) |
c54a2744 | 894 | WRITE_ONCE(first->pprev, &n->next); |
1c97be67 | 895 | WRITE_ONCE(h->first, n); |
c54a2744 | 896 | WRITE_ONCE(n->pprev, &h->first); |
1da177e4 LT |
897 | } |
898 | ||
46deb744 PM |
899 | /** |
900 | * hlist_add_before - add a new entry before the one specified | |
901 | * @n: new entry to be added | |
902 | * @next: hlist node to add it before, which must be non-NULL | |
903 | */ | |
1da177e4 | 904 | static inline void hlist_add_before(struct hlist_node *n, |
46deb744 | 905 | struct hlist_node *next) |
1da177e4 | 906 | { |
c54a2744 ED |
907 | WRITE_ONCE(n->pprev, next->pprev); |
908 | WRITE_ONCE(n->next, next); | |
909 | WRITE_ONCE(next->pprev, &n->next); | |
1c97be67 | 910 | WRITE_ONCE(*(n->pprev), n); |
1da177e4 LT |
911 | } |
912 | ||
46deb744 | 913 | /** |
4704bd31 | 914 | * hlist_add_behind - add a new entry after the one specified |
46deb744 PM |
915 | * @n: new entry to be added |
916 | * @prev: hlist node to add it after, which must be non-NULL | |
917 | */ | |
1d023284 KH |
918 | static inline void hlist_add_behind(struct hlist_node *n, |
919 | struct hlist_node *prev) | |
1da177e4 | 920 | { |
c54a2744 ED |
921 | WRITE_ONCE(n->next, prev->next); |
922 | WRITE_ONCE(prev->next, n); | |
923 | WRITE_ONCE(n->pprev, &prev->next); | |
1da177e4 | 924 | |
bc18dd33 | 925 | if (n->next) |
c54a2744 | 926 | WRITE_ONCE(n->next->pprev, &n->next); |
1da177e4 LT |
927 | } |
928 | ||
46deb744 PM |
929 | /** |
930 | * hlist_add_fake - create a fake hlist consisting of a single headless node | |
931 | * @n: Node to make a fake list out of | |
932 | * | |
933 | * This makes @n appear to be its own predecessor on a headless hlist. | |
934 | * The point of this is to allow things like hlist_del() to work correctly | |
935 | * in cases where there is no list. | |
936 | */ | |
756acc2d AV |
937 | static inline void hlist_add_fake(struct hlist_node *n) |
938 | { | |
939 | n->pprev = &n->next; | |
940 | } | |
941 | ||
46deb744 PM |
942 | /** |
943 | * hlist_fake: Is this node a fake hlist? | |
944 | * @h: Node to check for being a self-referential fake hlist. | |
945 | */ | |
cbedaac6 JB |
946 | static inline bool hlist_fake(struct hlist_node *h) |
947 | { | |
948 | return h->pprev == &h->next; | |
949 | } | |
950 | ||
46deb744 PM |
951 | /** |
952 | * hlist_is_singular_node - is node the only element of the specified hlist? | |
953 | * @n: Node to check for singularity. | |
954 | * @h: Header for potentially singular list. | |
955 | * | |
15dba1e3 | 956 | * Check whether the node is the only node of the head without |
46deb744 | 957 | * accessing head, thus avoiding unnecessary cache misses. |
15dba1e3 TG |
958 | */ |
959 | static inline bool | |
960 | hlist_is_singular_node(struct hlist_node *n, struct hlist_head *h) | |
961 | { | |
962 | return !n->next && n->pprev == &h->first; | |
963 | } | |
964 | ||
46deb744 PM |
965 | /** |
966 | * hlist_move_list - Move an hlist | |
967 | * @old: hlist_head for old list. | |
968 | * @new: hlist_head for new list. | |
969 | * | |
673d62cc VN |
970 | * Move a list from one list head to another. Fixup the pprev |
971 | * reference of the first entry if it exists. | |
972 | */ | |
973 | static inline void hlist_move_list(struct hlist_head *old, | |
974 | struct hlist_head *new) | |
975 | { | |
976 | new->first = old->first; | |
977 | if (new->first) | |
978 | new->first->pprev = &new->first; | |
979 | old->first = NULL; | |
980 | } | |
981 | ||
1da177e4 LT |
982 | #define hlist_entry(ptr, type, member) container_of(ptr,type,member) |
983 | ||
984 | #define hlist_for_each(pos, head) \ | |
75d65a42 | 985 | for (pos = (head)->first; pos ; pos = pos->next) |
1da177e4 LT |
986 | |
987 | #define hlist_for_each_safe(pos, n, head) \ | |
988 | for (pos = (head)->first; pos && ({ n = pos->next; 1; }); \ | |
989 | pos = n) | |
990 | ||
b67bfe0d | 991 | #define hlist_entry_safe(ptr, type, member) \ |
f65846a1 PM |
992 | ({ typeof(ptr) ____ptr = (ptr); \ |
993 | ____ptr ? hlist_entry(____ptr, type, member) : NULL; \ | |
994 | }) | |
b67bfe0d | 995 | |
1da177e4 LT |
996 | /** |
997 | * hlist_for_each_entry - iterate over list of given type | |
b67bfe0d | 998 | * @pos: the type * to use as a loop cursor. |
1da177e4 LT |
999 | * @head: the head for your list. |
1000 | * @member: the name of the hlist_node within the struct. | |
1001 | */ | |
b67bfe0d SL |
1002 | #define hlist_for_each_entry(pos, head, member) \ |
1003 | for (pos = hlist_entry_safe((head)->first, typeof(*(pos)), member);\ | |
1004 | pos; \ | |
1005 | pos = hlist_entry_safe((pos)->member.next, typeof(*(pos)), member)) | |
1da177e4 LT |
1006 | |
1007 | /** | |
fe96e57d | 1008 | * hlist_for_each_entry_continue - iterate over a hlist continuing after current point |
b67bfe0d | 1009 | * @pos: the type * to use as a loop cursor. |
1da177e4 LT |
1010 | * @member: the name of the hlist_node within the struct. |
1011 | */ | |
b67bfe0d SL |
1012 | #define hlist_for_each_entry_continue(pos, member) \ |
1013 | for (pos = hlist_entry_safe((pos)->member.next, typeof(*(pos)), member);\ | |
1014 | pos; \ | |
1015 | pos = hlist_entry_safe((pos)->member.next, typeof(*(pos)), member)) | |
1da177e4 LT |
1016 | |
1017 | /** | |
fe96e57d | 1018 | * hlist_for_each_entry_from - iterate over a hlist continuing from current point |
b67bfe0d | 1019 | * @pos: the type * to use as a loop cursor. |
1da177e4 LT |
1020 | * @member: the name of the hlist_node within the struct. |
1021 | */ | |
b67bfe0d SL |
1022 | #define hlist_for_each_entry_from(pos, member) \ |
1023 | for (; pos; \ | |
1024 | pos = hlist_entry_safe((pos)->member.next, typeof(*(pos)), member)) | |
1da177e4 LT |
1025 | |
1026 | /** | |
1027 | * hlist_for_each_entry_safe - iterate over list of given type safe against removal of list entry | |
b67bfe0d | 1028 | * @pos: the type * to use as a loop cursor. |
c84716c4 | 1029 | * @n: a &struct hlist_node to use as temporary storage |
1da177e4 LT |
1030 | * @head: the head for your list. |
1031 | * @member: the name of the hlist_node within the struct. | |
1032 | */ | |
b67bfe0d SL |
1033 | #define hlist_for_each_entry_safe(pos, n, head, member) \ |
1034 | for (pos = hlist_entry_safe((head)->first, typeof(*pos), member);\ | |
1035 | pos && ({ n = pos->member.next; 1; }); \ | |
1036 | pos = hlist_entry_safe(n, typeof(*pos), member)) | |
1da177e4 | 1037 | |
1da177e4 | 1038 | #endif |