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