1#ifndef _LINUX_LIST_H 2#define _LINUX_LIST_H 3 4#include <linux/types.h> 5#include <linux/stddef.h> 6#include <linux/poison.h> 7#include <linux/prefetch.h> 8#include <asm/system.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 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(struct list_head *entry) 101{ 102 __list_del(entry->prev, entry->next); 103 entry->next = LIST_POISON1; 104 entry->prev = LIST_POISON2; 105} 106#else 107extern void list_del(struct list_head *entry); 108#endif 109 110/** 111 * list_replace - replace old entry by new one 112 * @old : the element to be replaced 113 * @new : the new element to insert 114 * 115 * If @old was empty, it will be overwritten. 116 */ 117static inline void list_replace(struct list_head *old, 118 struct list_head *new) 119{ 120 new->next = old->next; 121 new->next->prev = new; 122 new->prev = old->prev; 123 new->prev->next = new; 124} 125 126static inline void list_replace_init(struct list_head *old, 127 struct list_head *new) 128{ 129 list_replace(old, new); 130 INIT_LIST_HEAD(old); 131} 132 133/** 134 * list_del_init - deletes entry from list and reinitialize it. 135 * @entry: the element to delete from the list. 136 */ 137static inline void list_del_init(struct list_head *entry) 138{ 139 __list_del(entry->prev, entry->next); 140 INIT_LIST_HEAD(entry); 141} 142 143/** 144 * list_move - delete from one list and add as another's head 145 * @list: the entry to move 146 * @head: the head that will precede our entry 147 */ 148static inline void list_move(struct list_head *list, struct list_head *head) 149{ 150 __list_del(list->prev, list->next); 151 list_add(list, head); 152} 153 154/** 155 * list_move_tail - delete from one list and add as another's tail 156 * @list: the entry to move 157 * @head: the head that will follow our entry 158 */ 159static inline void list_move_tail(struct list_head *list, 160 struct list_head *head) 161{ 162 __list_del(list->prev, list->next); 163 list_add_tail(list, head); 164} 165 166/** 167 * list_is_last - tests whether @list is the last entry in list @head 168 * @list: the entry to test 169 * @head: the head of the list 170 */ 171static inline int list_is_last(const struct list_head *list, 172 const struct list_head *head) 173{ 174 return list->next == head; 175} 176 177/** 178 * list_empty - tests whether a list is empty 179 * @head: the list to test. 180 */ 181static inline int list_empty(const struct list_head *head) 182{ 183 return head->next == head; 184} 185 186/** 187 * list_empty_careful - tests whether a list is empty and not being modified 188 * @head: the list to test 189 * 190 * Description: 191 * tests whether a list is empty _and_ checks that no other CPU might be 192 * in the process of modifying either member (next or prev) 193 * 194 * NOTE: using list_empty_careful() without synchronization 195 * can only be safe if the only activity that can happen 196 * to the list entry is list_del_init(). Eg. it cannot be used 197 * if another CPU could re-list_add() it. 198 */ 199static inline int list_empty_careful(const struct list_head *head) 200{ 201 struct list_head *next = head->next; 202 return (next == head) && (next == head->prev); 203} 204 205/** 206 * list_rotate_left - rotate the list to the left 207 * @head: the head of the list 208 */ 209static inline void list_rotate_left(struct list_head *head) 210{ 211 struct list_head *first; 212 213 if (!list_empty(head)) { 214 first = head->next; 215 list_move_tail(first, head); 216 } 217} 218 219/** 220 * list_is_singular - tests whether a list has just one entry. 221 * @head: the list to test. 222 */ 223static inline int list_is_singular(const struct list_head *head) 224{ 225 return !list_empty(head) && (head->next == head->prev); 226} 227 228static inline void __list_cut_position(struct list_head *list, 229 struct list_head *head, struct list_head *entry) 230{ 231 struct list_head *new_first = entry->next; 232 list->next = head->next; 233 list->next->prev = list; 234 list->prev = entry; 235 entry->next = list; 236 head->next = new_first; 237 new_first->prev = head; 238} 239 240/** 241 * list_cut_position - cut a list into two 242 * @list: a new list to add all removed entries 243 * @head: a list with entries 244 * @entry: an entry within head, could be the head itself 245 * and if so we won't cut the list 246 * 247 * This helper moves the initial part of @head, up to and 248 * including @entry, from @head to @list. You should 249 * pass on @entry an element you know is on @head. @list 250 * should be an empty list or a list you do not care about 251 * losing its data. 252 * 253 */ 254static inline void list_cut_position(struct list_head *list, 255 struct list_head *head, struct list_head *entry) 256{ 257 if (list_empty(head)) 258 return; 259 if (list_is_singular(head) && 260 (head->next != entry && head != entry)) 261 return; 262 if (entry == head) 263 INIT_LIST_HEAD(list); 264 else 265 __list_cut_position(list, head, entry); 266} 267 268static inline void __list_splice(const struct list_head *list, 269 struct list_head *prev, 270 struct list_head *next) 271{ 272 struct list_head *first = list->next; 273 struct list_head *last = list->prev; 274 275 first->prev = prev; 276 prev->next = first; 277 278 last->next = next; 279 next->prev = last; 280} 281 282/** 283 * list_splice - join two lists, this is designed for stacks 284 * @list: the new list to add. 285 * @head: the place to add it in the first list. 286 */ 287static inline void list_splice(const struct list_head *list, 288 struct list_head *head) 289{ 290 if (!list_empty(list)) 291 __list_splice(list, head, head->next); 292} 293 294/** 295 * list_splice_tail - join two lists, each list being a queue 296 * @list: the new list to add. 297 * @head: the place to add it in the first list. 298 */ 299static inline void list_splice_tail(struct list_head *list, 300 struct list_head *head) 301{ 302 if (!list_empty(list)) 303 __list_splice(list, head->prev, head); 304} 305 306/** 307 * list_splice_init - join two lists and reinitialise the emptied list. 308 * @list: the new list to add. 309 * @head: the place to add it in the first list. 310 * 311 * The list at @list is reinitialised 312 */ 313static inline void list_splice_init(struct list_head *list, 314 struct list_head *head) 315{ 316 if (!list_empty(list)) { 317 __list_splice(list, head, head->next); 318 INIT_LIST_HEAD(list); 319 } 320} 321 322/** 323 * list_splice_tail_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 * Each of the lists is a queue. 328 * The list at @list is reinitialised 329 */ 330static inline void list_splice_tail_init(struct list_head *list, 331 struct list_head *head) 332{ 333 if (!list_empty(list)) { 334 __list_splice(list, head->prev, head); 335 INIT_LIST_HEAD(list); 336 } 337} 338 339/** 340 * list_entry - get the struct for this entry 341 * @ptr: the &struct list_head pointer. 342 * @type: the type of the struct this is embedded in. 343 * @member: the name of the list_struct within the struct. 344 */ 345#define list_entry(ptr, type, member) \ 346 container_of(ptr, type, member) 347 348/** 349 * list_first_entry - get the first element from a list 350 * @ptr: the list head to take the element from. 351 * @type: the type of the struct this is embedded in. 352 * @member: the name of the list_struct within the struct. 353 * 354 * Note, that list is expected to be not empty. 355 */ 356#define list_first_entry(ptr, type, member) \ 357 list_entry((ptr)->next, type, member) 358 359/** 360 * list_for_each - iterate over a list 361 * @pos: the &struct list_head to use as a loop cursor. 362 * @head: the head for your list. 363 */ 364#define list_for_each(pos, head) \ 365 for (pos = (head)->next; prefetch(pos->next), pos != (head); \ 366 pos = pos->next) 367 368/** 369 * __list_for_each - iterate over a list 370 * @pos: the &struct list_head to use as a loop cursor. 371 * @head: the head for your list. 372 * 373 * This variant differs from list_for_each() in that it's the 374 * simplest possible list iteration code, no prefetching is done. 375 * Use this for code that knows the list to be very short (empty 376 * or 1 entry) most of the time. 377 */ 378#define __list_for_each(pos, head) \ 379 for (pos = (head)->next; pos != (head); pos = pos->next) 380 381/** 382 * list_for_each_prev - iterate over a list backwards 383 * @pos: the &struct list_head to use as a loop cursor. 384 * @head: the head for your list. 385 */ 386#define list_for_each_prev(pos, head) \ 387 for (pos = (head)->prev; prefetch(pos->prev), pos != (head); \ 388 pos = pos->prev) 389 390/** 391 * list_for_each_safe - iterate over a list safe against removal of list entry 392 * @pos: the &struct list_head to use as a loop cursor. 393 * @n: another &struct list_head to use as temporary storage 394 * @head: the head for your list. 395 */ 396#define list_for_each_safe(pos, n, head) \ 397 for (pos = (head)->next, n = pos->next; pos != (head); \ 398 pos = n, n = pos->next) 399 400/** 401 * list_for_each_prev_safe - iterate over a list backwards safe against removal of list entry 402 * @pos: the &struct list_head to use as a loop cursor. 403 * @n: another &struct list_head to use as temporary storage 404 * @head: the head for your list. 405 */ 406#define list_for_each_prev_safe(pos, n, head) \ 407 for (pos = (head)->prev, n = pos->prev; \ 408 prefetch(pos->prev), pos != (head); \ 409 pos = n, n = pos->prev) 410 411/** 412 * list_for_each_entry - iterate 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(pos, head, member) \ 418 for (pos = list_entry((head)->next, typeof(*pos), member); \ 419 prefetch(pos->member.next), &pos->member != (head); \ 420 pos = list_entry(pos->member.next, typeof(*pos), member)) 421 422/** 423 * list_for_each_entry_reverse - iterate backwards over list of given type. 424 * @pos: the type * to use as a loop cursor. 425 * @head: the head for your list. 426 * @member: the name of the list_struct within the struct. 427 */ 428#define list_for_each_entry_reverse(pos, head, member) \ 429 for (pos = list_entry((head)->prev, typeof(*pos), member); \ 430 prefetch(pos->member.prev), &pos->member != (head); \ 431 pos = list_entry(pos->member.prev, typeof(*pos), member)) 432 433/** 434 * list_prepare_entry - prepare a pos entry for use in list_for_each_entry_continue() 435 * @pos: the type * to use as a start point 436 * @head: the head of the list 437 * @member: the name of the list_struct within the struct. 438 * 439 * Prepares a pos entry for use as a start point in list_for_each_entry_continue(). 440 */ 441#define list_prepare_entry(pos, head, member) \ 442 ((pos) ? : list_entry(head, typeof(*pos), member)) 443 444/** 445 * list_for_each_entry_continue - continue iteration over list of given type 446 * @pos: the type * to use as a loop cursor. 447 * @head: the head for your list. 448 * @member: the name of the list_struct within the struct. 449 * 450 * Continue to iterate over list of given type, continuing after 451 * the current position. 452 */ 453#define list_for_each_entry_continue(pos, head, member) \ 454 for (pos = list_entry(pos->member.next, typeof(*pos), member); \ 455 prefetch(pos->member.next), &pos->member != (head); \ 456 pos = list_entry(pos->member.next, typeof(*pos), member)) 457 458/** 459 * list_for_each_entry_continue_reverse - iterate backwards from the given point 460 * @pos: the type * to use as a loop cursor. 461 * @head: the head for your list. 462 * @member: the name of the list_struct within the struct. 463 * 464 * Start to iterate over list of given type backwards, continuing after 465 * the current position. 466 */ 467#define list_for_each_entry_continue_reverse(pos, head, member) \ 468 for (pos = list_entry(pos->member.prev, typeof(*pos), member); \ 469 prefetch(pos->member.prev), &pos->member != (head); \ 470 pos = list_entry(pos->member.prev, typeof(*pos), member)) 471 472/** 473 * list_for_each_entry_from - iterate over list of given type from the current point 474 * @pos: the type * to use as a loop cursor. 475 * @head: the head for your list. 476 * @member: the name of the list_struct within the struct. 477 * 478 * Iterate over list of given type, continuing from current position. 479 */ 480#define list_for_each_entry_from(pos, head, member) \ 481 for (; prefetch(pos->member.next), &pos->member != (head); \ 482 pos = list_entry(pos->member.next, typeof(*pos), member)) 483 484/** 485 * list_for_each_entry_safe - iterate over list of given type safe against removal of list entry 486 * @pos: the type * to use as a loop cursor. 487 * @n: another type * to use as temporary storage 488 * @head: the head for your list. 489 * @member: the name of the list_struct within the struct. 490 */ 491#define list_for_each_entry_safe(pos, n, head, member) \ 492 for (pos = list_entry((head)->next, typeof(*pos), member), \ 493 n = list_entry(pos->member.next, typeof(*pos), member); \ 494 &pos->member != (head); \ 495 pos = n, n = list_entry(n->member.next, typeof(*n), member)) 496 497/** 498 * list_for_each_entry_safe_continue - continue list iteration safe against removal 499 * @pos: the type * to use as a loop cursor. 500 * @n: another type * to use as temporary storage 501 * @head: the head for your list. 502 * @member: the name of the list_struct within the struct. 503 * 504 * Iterate over list of given type, continuing after current point, 505 * safe against removal of list entry. 506 */ 507#define list_for_each_entry_safe_continue(pos, n, head, member) \ 508 for (pos = list_entry(pos->member.next, typeof(*pos), member), \ 509 n = list_entry(pos->member.next, typeof(*pos), member); \ 510 &pos->member != (head); \ 511 pos = n, n = list_entry(n->member.next, typeof(*n), member)) 512 513/** 514 * list_for_each_entry_safe_from - iterate over list from current point safe against removal 515 * @pos: the type * to use as a loop cursor. 516 * @n: another type * to use as temporary storage 517 * @head: the head for your list. 518 * @member: the name of the list_struct within the struct. 519 * 520 * Iterate over list of given type from current point, safe against 521 * removal of list entry. 522 */ 523#define list_for_each_entry_safe_from(pos, n, head, member) \ 524 for (n = list_entry(pos->member.next, typeof(*pos), member); \ 525 &pos->member != (head); \ 526 pos = n, n = list_entry(n->member.next, typeof(*n), member)) 527 528/** 529 * list_for_each_entry_safe_reverse - iterate backwards over list safe against removal 530 * @pos: the type * to use as a loop cursor. 531 * @n: another type * to use as temporary storage 532 * @head: the head for your list. 533 * @member: the name of the list_struct within the struct. 534 * 535 * Iterate backwards over list of given type, safe against removal 536 * of list entry. 537 */ 538#define list_for_each_entry_safe_reverse(pos, n, head, member) \ 539 for (pos = list_entry((head)->prev, typeof(*pos), member), \ 540 n = list_entry(pos->member.prev, typeof(*pos), member); \ 541 &pos->member != (head); \ 542 pos = n, n = list_entry(n->member.prev, typeof(*n), member)) 543 544/** 545 * list_safe_reset_next - reset a stale list_for_each_entry_safe loop 546 * @pos: the loop cursor used in the list_for_each_entry_safe loop 547 * @n: temporary storage used in list_for_each_entry_safe 548 * @member: the name of the list_struct within the struct. 549 * 550 * list_safe_reset_next is not safe to use in general if the list may be 551 * modified concurrently (eg. the lock is dropped in the loop body). An 552 * exception to this is if the cursor element (pos) is pinned in the list, 553 * and list_safe_reset_next is called after re-taking the lock and before 554 * completing the current iteration of the loop body. 555 */ 556#define list_safe_reset_next(pos, n, member) \ 557 n = list_entry(pos->member.next, typeof(*pos), member) 558 559/* 560 * Double linked lists with a single pointer list head. 561 * Mostly useful for hash tables where the two pointer list head is 562 * too wasteful. 563 * You lose the ability to access the tail in O(1). 564 */ 565 566#define HLIST_HEAD_INIT { .first = NULL } 567#define HLIST_HEAD(name) struct hlist_head name = { .first = NULL } 568#define INIT_HLIST_HEAD(ptr) ((ptr)->first = NULL) 569static inline void INIT_HLIST_NODE(struct hlist_node *h) 570{ 571 h->next = NULL; 572 h->pprev = NULL; 573} 574 575static inline int hlist_unhashed(const struct hlist_node *h) 576{ 577 return !h->pprev; 578} 579 580static inline int hlist_empty(const struct hlist_head *h) 581{ 582 return !h->first; 583} 584 585static inline void __hlist_del(struct hlist_node *n) 586{ 587 struct hlist_node *next = n->next; 588 struct hlist_node **pprev = n->pprev; 589 *pprev = next; 590 if (next) 591 next->pprev = pprev; 592} 593 594static inline void hlist_del(struct hlist_node *n) 595{ 596 __hlist_del(n); 597 n->next = LIST_POISON1; 598 n->pprev = LIST_POISON2; 599} 600 601static inline void hlist_del_init(struct hlist_node *n) 602{ 603 if (!hlist_unhashed(n)) { 604 __hlist_del(n); 605 INIT_HLIST_NODE(n); 606 } 607} 608 609static inline void hlist_add_head(struct hlist_node *n, struct hlist_head *h) 610{ 611 struct hlist_node *first = h->first; 612 n->next = first; 613 if (first) 614 first->pprev = &n->next; 615 h->first = n; 616 n->pprev = &h->first; 617} 618 619/* next must be != NULL */ 620static inline void hlist_add_before(struct hlist_node *n, 621 struct hlist_node *next) 622{ 623 n->pprev = next->pprev; 624 n->next = next; 625 next->pprev = &n->next; 626 *(n->pprev) = n; 627} 628 629static inline void hlist_add_after(struct hlist_node *n, 630 struct hlist_node *next) 631{ 632 next->next = n->next; 633 n->next = next; 634 next->pprev = &n->next; 635 636 if(next->next) 637 next->next->pprev = &next->next; 638} 639 640/* 641 * Move a list from one list head to another. Fixup the pprev 642 * reference of the first entry if it exists. 643 */ 644static inline void hlist_move_list(struct hlist_head *old, 645 struct hlist_head *new) 646{ 647 new->first = old->first; 648 if (new->first) 649 new->first->pprev = &new->first; 650 old->first = NULL; 651} 652 653#define hlist_entry(ptr, type, member) container_of(ptr,type,member) 654 655#define hlist_for_each(pos, head) \ 656 for (pos = (head)->first; pos && ({ prefetch(pos->next); 1; }); \ 657 pos = pos->next) 658 659#define hlist_for_each_safe(pos, n, head) \ 660 for (pos = (head)->first; pos && ({ n = pos->next; 1; }); \ 661 pos = n) 662 663/** 664 * hlist_for_each_entry - iterate over list of given type 665 * @tpos: the type * to use as a loop cursor. 666 * @pos: the &struct hlist_node to use as a loop cursor. 667 * @head: the head for your list. 668 * @member: the name of the hlist_node within the struct. 669 */ 670#define hlist_for_each_entry(tpos, pos, head, member) \ 671 for (pos = (head)->first; \ 672 pos && ({ prefetch(pos->next); 1;}) && \ 673 ({ tpos = hlist_entry(pos, typeof(*tpos), member); 1;}); \ 674 pos = pos->next) 675 676/** 677 * hlist_for_each_entry_continue - iterate over a hlist continuing after current point 678 * @tpos: the type * to use as a loop cursor. 679 * @pos: the &struct hlist_node to use as a loop cursor. 680 * @member: the name of the hlist_node within the struct. 681 */ 682#define hlist_for_each_entry_continue(tpos, pos, member) \ 683 for (pos = (pos)->next; \ 684 pos && ({ prefetch(pos->next); 1;}) && \ 685 ({ tpos = hlist_entry(pos, typeof(*tpos), member); 1;}); \ 686 pos = pos->next) 687 688/** 689 * hlist_for_each_entry_from - iterate over a hlist continuing from current point 690 * @tpos: the type * to use as a loop cursor. 691 * @pos: the &struct hlist_node to use as a loop cursor. 692 * @member: the name of the hlist_node within the struct. 693 */ 694#define hlist_for_each_entry_from(tpos, pos, member) \ 695 for (; pos && ({ prefetch(pos->next); 1;}) && \ 696 ({ tpos = hlist_entry(pos, typeof(*tpos), member); 1;}); \ 697 pos = pos->next) 698 699/** 700 * hlist_for_each_entry_safe - iterate over list of given type safe against removal of list entry 701 * @tpos: the type * to use as a loop cursor. 702 * @pos: the &struct hlist_node to use as a loop cursor. 703 * @n: another &struct hlist_node to use as temporary storage 704 * @head: the head for your list. 705 * @member: the name of the hlist_node within the struct. 706 */ 707#define hlist_for_each_entry_safe(tpos, pos, n, head, member) \ 708 for (pos = (head)->first; \ 709 pos && ({ n = pos->next; 1; }) && \ 710 ({ tpos = hlist_entry(pos, typeof(*tpos), member); 1;}); \ 711 pos = n) 712 713#endif 714