1 #ifndef _LINUX_LIST_H 2 #define _LINUX_LIST_H 3 4 #ifdef __KERNEL__ 5 6 #include <linux/stddef.h> 7 #include <linux/poison.h> 8 #include <linux/prefetch.h> 9 #include <asm/system.h> 10 11 /* 12 * Simple doubly linked list implementation. 13 * 14 * Some of the internal functions ("__xxx") are useful when 15 * manipulating whole lists rather than single entries, as 16 * sometimes we already know the next/prev entries and we can 17 * generate better code by using them directly rather than 18 * using the generic single-entry routines. 19 */ 20 21 struct list_head { 22 struct list_head *next, *prev; 23 }; 24 25 #define LIST_HEAD_INIT(name) { &(name), &(name) } 26 27 #define LIST_HEAD(name) \ 28 struct list_head name = LIST_HEAD_INIT(name) 29 30 static inline void INIT_LIST_HEAD(struct list_head *list) 31 { 32 list->next = list; 33 list->prev = list; 34 } 35 36 /* 37 * Insert a new entry between two known consecutive entries. 38 * 39 * This is only for internal list manipulation where we know 40 * the prev/next entries already! 41 */ 42 static inline void __list_add(struct list_head *new, 43 struct list_head *prev, 44 struct list_head *next) 45 { 46 next->prev = new; 47 new->next = next; 48 new->prev = prev; 49 prev->next = new; 50 } 51 52 /** 53 * list_add - add a new entry 54 * @new: new entry to be added 55 * @head: list head to add it after 56 * 57 * Insert a new entry after the specified head. 58 * This is good for implementing stacks. 59 */ 60 static inline void list_add(struct list_head *new, struct list_head *head) 61 { 62 __list_add(new, head, head->next); 63 } 64 65 /** 66 * list_add_tail - add a new entry 67 * @new: new entry to be added 68 * @head: list head to add it before 69 * 70 * Insert a new entry before the specified head. 71 * This is useful for implementing queues. 72 */ 73 static inline void list_add_tail(struct list_head *new, struct list_head *head) 74 { 75 __list_add(new, head->prev, head); 76 } 77 78 /* 79 * Insert a new entry between two known consecutive entries. 80 * 81 * This is only for internal list manipulation where we know 82 * the prev/next entries already! 83 */ 84 static inline void __list_add_rcu(struct list_head * new, 85 struct list_head * prev, struct list_head * next) 86 { 87 new->next = next; 88 new->prev = prev; 89 smp_wmb(); 90 next->prev = new; 91 prev->next = new; 92 } 93 94 /** 95 * list_add_rcu - add a new entry to rcu-protected list 96 * @new: new entry to be added 97 * @head: list head to add it after 98 * 99 * Insert a new entry after the specified head. 100 * This is good for implementing stacks. 101 * 102 * The caller must take whatever precautions are necessary 103 * (such as holding appropriate locks) to avoid racing 104 * with another list-mutation primitive, such as list_add_rcu() 105 * or list_del_rcu(), running on this same list. 106 * However, it is perfectly legal to run concurrently with 107 * the _rcu list-traversal primitives, such as 108 * list_for_each_entry_rcu(). 109 */ 110 static inline void list_add_rcu(struct list_head *new, struct list_head *head) 111 { 112 __list_add_rcu(new, head, head->next); 113 } 114 115 /** 116 * list_add_tail_rcu - add a new entry to rcu-protected list 117 * @new: new entry to be added 118 * @head: list head to add it before 119 * 120 * Insert a new entry before the specified head. 121 * This is useful for implementing queues. 122 * 123 * The caller must take whatever precautions are necessary 124 * (such as holding appropriate locks) to avoid racing 125 * with another list-mutation primitive, such as list_add_tail_rcu() 126 * or list_del_rcu(), running on this same list. 127 * However, it is perfectly legal to run concurrently with 128 * the _rcu list-traversal primitives, such as 129 * list_for_each_entry_rcu(). 130 */ 131 static inline void list_add_tail_rcu(struct list_head *new, 132 struct list_head *head) 133 { 134 __list_add_rcu(new, head->prev, head); 135 } 136 137 /* 138 * Delete a list entry by making the prev/next entries 139 * point to each other. 140 * 141 * This is only for internal list manipulation where we know 142 * the prev/next entries already! 143 */ 144 static inline void __list_del(struct list_head * prev, struct list_head * next) 145 { 146 next->prev = prev; 147 prev->next = next; 148 } 149 150 /** 151 * list_del - deletes entry from list. 152 * @entry: the element to delete from the list. 153 * Note: list_empty on entry does not return true after this, the entry is 154 * in an undefined state. 155 */ 156 static inline void list_del(struct list_head *entry) 157 { 158 __list_del(entry->prev, entry->next); 159 entry->next = LIST_POISON1; 160 entry->prev = LIST_POISON2; 161 } 162 163 /** 164 * list_del_rcu - deletes entry from list without re-initialization 165 * @entry: the element to delete from the list. 166 * 167 * Note: list_empty on entry does not return true after this, 168 * the entry is in an undefined state. It is useful for RCU based 169 * lockfree traversal. 170 * 171 * In particular, it means that we can not poison the forward 172 * pointers that may still be used for walking the list. 173 * 174 * The caller must take whatever precautions are necessary 175 * (such as holding appropriate locks) to avoid racing 176 * with another list-mutation primitive, such as list_del_rcu() 177 * or list_add_rcu(), running on this same list. 178 * However, it is perfectly legal to run concurrently with 179 * the _rcu list-traversal primitives, such as 180 * list_for_each_entry_rcu(). 181 * 182 * Note that the caller is not permitted to immediately free 183 * the newly deleted entry. Instead, either synchronize_rcu() 184 * or call_rcu() must be used to defer freeing until an RCU 185 * grace period has elapsed. 186 */ 187 static inline void list_del_rcu(struct list_head *entry) 188 { 189 __list_del(entry->prev, entry->next); 190 entry->prev = LIST_POISON2; 191 } 192 193 /** 194 * list_replace - replace old entry by new one 195 * @old : the element to be replaced 196 * @new : the new element to insert 197 * Note: if 'old' was empty, it will be overwritten. 198 */ 199 static inline void list_replace(struct list_head *old, 200 struct list_head *new) 201 { 202 new->next = old->next; 203 new->next->prev = new; 204 new->prev = old->prev; 205 new->prev->next = new; 206 } 207 208 static inline void list_replace_init(struct list_head *old, 209 struct list_head *new) 210 { 211 list_replace(old, new); 212 INIT_LIST_HEAD(old); 213 } 214 215 /* 216 * list_replace_rcu - replace old entry by new one 217 * @old : the element to be replaced 218 * @new : the new element to insert 219 * 220 * The old entry will be replaced with the new entry atomically. 221 * Note: 'old' should not be empty. 222 */ 223 static inline void list_replace_rcu(struct list_head *old, 224 struct list_head *new) 225 { 226 new->next = old->next; 227 new->prev = old->prev; 228 smp_wmb(); 229 new->next->prev = new; 230 new->prev->next = new; 231 old->prev = LIST_POISON2; 232 } 233 234 /** 235 * list_del_init - deletes entry from list and reinitialize it. 236 * @entry: the element to delete from the list. 237 */ 238 static inline void list_del_init(struct list_head *entry) 239 { 240 __list_del(entry->prev, entry->next); 241 INIT_LIST_HEAD(entry); 242 } 243 244 /** 245 * list_move - delete from one list and add as another's head 246 * @list: the entry to move 247 * @head: the head that will precede our entry 248 */ 249 static inline void list_move(struct list_head *list, struct list_head *head) 250 { 251 __list_del(list->prev, list->next); 252 list_add(list, head); 253 } 254 255 /** 256 * list_move_tail - delete from one list and add as another's tail 257 * @list: the entry to move 258 * @head: the head that will follow our entry 259 */ 260 static inline void list_move_tail(struct list_head *list, 261 struct list_head *head) 262 { 263 __list_del(list->prev, list->next); 264 list_add_tail(list, head); 265 } 266 267 /** 268 * list_is_last - tests whether @list is the last entry in list @head 269 * @list: the entry to test 270 * @head: the head of the list 271 */ 272 static inline int list_is_last(const struct list_head *list, 273 const struct list_head *head) 274 { 275 return list->next == head; 276 } 277 278 /** 279 * list_empty - tests whether a list is empty 280 * @head: the list to test. 281 */ 282 static inline int list_empty(const struct list_head *head) 283 { 284 return head->next == head; 285 } 286 287 /** 288 * list_empty_careful - tests whether a list is empty and not being modified 289 * @head: the list to test 290 * 291 * Description: 292 * tests whether a list is empty _and_ checks that no other CPU might be 293 * in the process of modifying either member (next or prev) 294 * 295 * NOTE: using list_empty_careful() without synchronization 296 * can only be safe if the only activity that can happen 297 * to the list entry is list_del_init(). Eg. it cannot be used 298 * if another CPU could re-list_add() it. 299 */ 300 static inline int list_empty_careful(const struct list_head *head) 301 { 302 struct list_head *next = head->next; 303 return (next == head) && (next == head->prev); 304 } 305 306 static inline void __list_splice(struct list_head *list, 307 struct list_head *head) 308 { 309 struct list_head *first = list->next; 310 struct list_head *last = list->prev; 311 struct list_head *at = head->next; 312 313 first->prev = head; 314 head->next = first; 315 316 last->next = at; 317 at->prev = last; 318 } 319 320 /** 321 * list_splice - join two lists 322 * @list: the new list to add. 323 * @head: the place to add it in the first list. 324 */ 325 static inline void list_splice(struct list_head *list, struct list_head *head) 326 { 327 if (!list_empty(list)) 328 __list_splice(list, head); 329 } 330 331 /** 332 * list_splice_init - join two lists and reinitialise the emptied list. 333 * @list: the new list to add. 334 * @head: the place to add it in the first list. 335 * 336 * The list at @list is reinitialised 337 */ 338 static inline void list_splice_init(struct list_head *list, 339 struct list_head *head) 340 { 341 if (!list_empty(list)) { 342 __list_splice(list, head); 343 INIT_LIST_HEAD(list); 344 } 345 } 346 347 /** 348 * list_entry - get the struct for this entry 349 * @ptr: the &struct list_head pointer. 350 * @type: the type of the struct this is embedded in. 351 * @member: the name of the list_struct within the struct. 352 */ 353 #define list_entry(ptr, type, member) \ 354 container_of(ptr, type, member) 355 356 /** 357 * list_for_each - iterate over a list 358 * @pos: the &struct list_head to use as a loop cursor. 359 * @head: the head for your list. 360 */ 361 #define list_for_each(pos, head) \ 362 for (pos = (head)->next; prefetch(pos->next), pos != (head); \ 363 pos = pos->next) 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 * This variant differs from list_for_each() in that it's the 371 * simplest possible list iteration code, no prefetching is done. 372 * Use this for code that knows the list to be very short (empty 373 * or 1 entry) most of the time. 374 */ 375 #define __list_for_each(pos, head) \ 376 for (pos = (head)->next; pos != (head); pos = pos->next) 377 378 /** 379 * list_for_each_prev - iterate over a list backwards 380 * @pos: the &struct list_head to use as a loop cursor. 381 * @head: the head for your list. 382 */ 383 #define list_for_each_prev(pos, head) \ 384 for (pos = (head)->prev; prefetch(pos->prev), pos != (head); \ 385 pos = pos->prev) 386 387 /** 388 * list_for_each_safe - iterate over a list safe against removal of list entry 389 * @pos: the &struct list_head to use as a loop cursor. 390 * @n: another &struct list_head to use as temporary storage 391 * @head: the head for your list. 392 */ 393 #define list_for_each_safe(pos, n, head) \ 394 for (pos = (head)->next, n = pos->next; pos != (head); \ 395 pos = n, n = pos->next) 396 397 /** 398 * list_for_each_entry - iterate over list of given type 399 * @pos: the type * to use as a loop cursor. 400 * @head: the head for your list. 401 * @member: the name of the list_struct within the struct. 402 */ 403 #define list_for_each_entry(pos, head, member) \ 404 for (pos = list_entry((head)->next, typeof(*pos), member); \ 405 prefetch(pos->member.next), &pos->member != (head); \ 406 pos = list_entry(pos->member.next, typeof(*pos), member)) 407 408 /** 409 * list_for_each_entry_reverse - iterate backwards over list of given type. 410 * @pos: the type * to use as a loop cursor. 411 * @head: the head for your list. 412 * @member: the name of the list_struct within the struct. 413 */ 414 #define list_for_each_entry_reverse(pos, head, member) \ 415 for (pos = list_entry((head)->prev, typeof(*pos), member); \ 416 prefetch(pos->member.prev), &pos->member != (head); \ 417 pos = list_entry(pos->member.prev, typeof(*pos), member)) 418 419 /** 420 * list_prepare_entry - prepare a pos entry for use in list_for_each_entry_continue 421 * @pos: the type * to use as a start point 422 * @head: the head of the list 423 * @member: the name of the list_struct within the struct. 424 * 425 * Prepares a pos entry for use as a start point in list_for_each_entry_continue. 426 */ 427 #define list_prepare_entry(pos, head, member) \ 428 ((pos) ? : list_entry(head, typeof(*pos), member)) 429 430 /** 431 * list_for_each_entry_continue - continue iteration over list of given type 432 * @pos: the type * to use as a loop cursor. 433 * @head: the head for your list. 434 * @member: the name of the list_struct within the struct. 435 * 436 * Continue to iterate over list of given type, continuing after 437 * the current position. 438 */ 439 #define list_for_each_entry_continue(pos, head, member) \ 440 for (pos = list_entry(pos->member.next, typeof(*pos), member); \ 441 prefetch(pos->member.next), &pos->member != (head); \ 442 pos = list_entry(pos->member.next, typeof(*pos), member)) 443 444 /** 445 * list_for_each_entry_from - iterate over list of given type from the current point 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 * Iterate over list of given type, continuing from current position. 451 */ 452 #define list_for_each_entry_from(pos, head, member) \ 453 for (; prefetch(pos->member.next), &pos->member != (head); \ 454 pos = list_entry(pos->member.next, typeof(*pos), member)) 455 456 /** 457 * list_for_each_entry_safe - iterate over list of given type safe against removal of list entry 458 * @pos: the type * to use as a loop cursor. 459 * @n: another type * to use as temporary storage 460 * @head: the head for your list. 461 * @member: the name of the list_struct within the struct. 462 */ 463 #define list_for_each_entry_safe(pos, n, head, member) \ 464 for (pos = list_entry((head)->next, typeof(*pos), member), \ 465 n = list_entry(pos->member.next, typeof(*pos), member); \ 466 &pos->member != (head); \ 467 pos = n, n = list_entry(n->member.next, typeof(*n), member)) 468 469 /** 470 * list_for_each_entry_safe_continue 471 * @pos: the type * to use as a loop cursor. 472 * @n: another type * to use as temporary storage 473 * @head: the head for your list. 474 * @member: the name of the list_struct within the struct. 475 * 476 * Iterate over list of given type, continuing after current point, 477 * safe against removal of list entry. 478 */ 479 #define list_for_each_entry_safe_continue(pos, n, head, member) \ 480 for (pos = list_entry(pos->member.next, typeof(*pos), member), \ 481 n = list_entry(pos->member.next, typeof(*pos), member); \ 482 &pos->member != (head); \ 483 pos = n, n = list_entry(n->member.next, typeof(*n), member)) 484 485 /** 486 * list_for_each_entry_safe_from 487 * @pos: the type * to use as a loop cursor. 488 * @n: another type * to use as temporary storage 489 * @head: the head for your list. 490 * @member: the name of the list_struct within the struct. 491 * 492 * Iterate over list of given type from current point, safe against 493 * removal of list entry. 494 */ 495 #define list_for_each_entry_safe_from(pos, n, head, member) \ 496 for (n = list_entry(pos->member.next, typeof(*pos), member); \ 497 &pos->member != (head); \ 498 pos = n, n = list_entry(n->member.next, typeof(*n), member)) 499 500 /** 501 * list_for_each_entry_safe_reverse 502 * @pos: the type * to use as a loop cursor. 503 * @n: another type * to use as temporary storage 504 * @head: the head for your list. 505 * @member: the name of the list_struct within the struct. 506 * 507 * Iterate backwards over list of given type, safe against removal 508 * of list entry. 509 */ 510 #define list_for_each_entry_safe_reverse(pos, n, head, member) \ 511 for (pos = list_entry((head)->prev, typeof(*pos), member), \ 512 n = list_entry(pos->member.prev, typeof(*pos), member); \ 513 &pos->member != (head); \ 514 pos = n, n = list_entry(n->member.prev, typeof(*n), member)) 515 516 /** 517 * list_for_each_rcu - iterate over an rcu-protected list 518 * @pos: the &struct list_head to use as a loop cursor. 519 * @head: the head for your list. 520 * 521 * This list-traversal primitive may safely run concurrently with 522 * the _rcu list-mutation primitives such as list_add_rcu() 523 * as long as the traversal is guarded by rcu_read_lock(). 524 */ 525 #define list_for_each_rcu(pos, head) \ 526 for (pos = (head)->next; \ 527 prefetch(rcu_dereference(pos)->next), pos != (head); \ 528 pos = pos->next) 529 530 #define __list_for_each_rcu(pos, head) \ 531 for (pos = (head)->next; \ 532 rcu_dereference(pos) != (head); \ 533 pos = pos->next) 534 535 /** 536 * list_for_each_safe_rcu 537 * @pos: the &struct list_head to use as a loop cursor. 538 * @n: another &struct list_head to use as temporary storage 539 * @head: the head for your list. 540 * 541 * Iterate over an rcu-protected list, safe against removal of list entry. 542 * 543 * This list-traversal primitive may safely run concurrently with 544 * the _rcu list-mutation primitives such as list_add_rcu() 545 * as long as the traversal is guarded by rcu_read_lock(). 546 */ 547 #define list_for_each_safe_rcu(pos, n, head) \ 548 for (pos = (head)->next; \ 549 n = rcu_dereference(pos)->next, pos != (head); \ 550 pos = n) 551 552 /** 553 * list_for_each_entry_rcu - iterate over rcu list of given type 554 * @pos: the type * to use as a loop cursor. 555 * @head: the head for your list. 556 * @member: the name of the list_struct within the struct. 557 * 558 * This list-traversal primitive may safely run concurrently with 559 * the _rcu list-mutation primitives such as list_add_rcu() 560 * as long as the traversal is guarded by rcu_read_lock(). 561 */ 562 #define list_for_each_entry_rcu(pos, head, member) \ 563 for (pos = list_entry((head)->next, typeof(*pos), member); \ 564 prefetch(rcu_dereference(pos)->member.next), \ 565 &pos->member != (head); \ 566 pos = list_entry(pos->member.next, typeof(*pos), member)) 567 568 569 /** 570 * list_for_each_continue_rcu 571 * @pos: the &struct list_head to use as a loop cursor. 572 * @head: the head for your list. 573 * 574 * Iterate over an rcu-protected list, continuing after current point. 575 * 576 * This list-traversal primitive may safely run concurrently with 577 * the _rcu list-mutation primitives such as list_add_rcu() 578 * as long as the traversal is guarded by rcu_read_lock(). 579 */ 580 #define list_for_each_continue_rcu(pos, head) \ 581 for ((pos) = (pos)->next; \ 582 prefetch(rcu_dereference((pos))->next), (pos) != (head); \ 583 (pos) = (pos)->next) 584 585 /* 586 * Double linked lists with a single pointer list head. 587 * Mostly useful for hash tables where the two pointer list head is 588 * too wasteful. 589 * You lose the ability to access the tail in O(1). 590 */ 591 592 struct hlist_head { 593 struct hlist_node *first; 594 }; 595 596 struct hlist_node { 597 struct hlist_node *next, **pprev; 598 }; 599 600 #define HLIST_HEAD_INIT { .first = NULL } 601 #define HLIST_HEAD(name) struct hlist_head name = { .first = NULL } 602 #define INIT_HLIST_HEAD(ptr) ((ptr)->first = NULL) 603 static inline void INIT_HLIST_NODE(struct hlist_node *h) 604 { 605 h->next = NULL; 606 h->pprev = NULL; 607 } 608 609 static inline int hlist_unhashed(const struct hlist_node *h) 610 { 611 return !h->pprev; 612 } 613 614 static inline int hlist_empty(const struct hlist_head *h) 615 { 616 return !h->first; 617 } 618 619 static inline void __hlist_del(struct hlist_node *n) 620 { 621 struct hlist_node *next = n->next; 622 struct hlist_node **pprev = n->pprev; 623 *pprev = next; 624 if (next) 625 next->pprev = pprev; 626 } 627 628 static inline void hlist_del(struct hlist_node *n) 629 { 630 __hlist_del(n); 631 n->next = LIST_POISON1; 632 n->pprev = LIST_POISON2; 633 } 634 635 /** 636 * hlist_del_rcu - deletes entry from hash list without re-initialization 637 * @n: the element to delete from the hash list. 638 * 639 * Note: list_unhashed() on entry does not return true after this, 640 * the entry is in an undefined state. It is useful for RCU based 641 * lockfree traversal. 642 * 643 * In particular, it means that we can not poison the forward 644 * pointers that may still be used for walking the hash list. 645 * 646 * The caller must take whatever precautions are necessary 647 * (such as holding appropriate locks) to avoid racing 648 * with another list-mutation primitive, such as hlist_add_head_rcu() 649 * or hlist_del_rcu(), running on this same list. 650 * However, it is perfectly legal to run concurrently with 651 * the _rcu list-traversal primitives, such as 652 * hlist_for_each_entry(). 653 */ 654 static inline void hlist_del_rcu(struct hlist_node *n) 655 { 656 __hlist_del(n); 657 n->pprev = LIST_POISON2; 658 } 659 660 static inline void hlist_del_init(struct hlist_node *n) 661 { 662 if (!hlist_unhashed(n)) { 663 __hlist_del(n); 664 INIT_HLIST_NODE(n); 665 } 666 } 667 668 /* 669 * hlist_replace_rcu - replace old entry by new one 670 * @old : the element to be replaced 671 * @new : the new element to insert 672 * 673 * The old entry will be replaced with the new entry atomically. 674 */ 675 static inline void hlist_replace_rcu(struct hlist_node *old, 676 struct hlist_node *new) 677 { 678 struct hlist_node *next = old->next; 679 680 new->next = next; 681 new->pprev = old->pprev; 682 smp_wmb(); 683 if (next) 684 new->next->pprev = &new->next; 685 *new->pprev = new; 686 old->pprev = LIST_POISON2; 687 } 688 689 static inline void hlist_add_head(struct hlist_node *n, struct hlist_head *h) 690 { 691 struct hlist_node *first = h->first; 692 n->next = first; 693 if (first) 694 first->pprev = &n->next; 695 h->first = n; 696 n->pprev = &h->first; 697 } 698 699 700 /** 701 * hlist_add_head_rcu 702 * @n: the element to add to the hash list. 703 * @h: the list to add to. 704 * 705 * Description: 706 * Adds the specified element to the specified hlist, 707 * while permitting racing traversals. 708 * 709 * The caller must take whatever precautions are necessary 710 * (such as holding appropriate locks) to avoid racing 711 * with another list-mutation primitive, such as hlist_add_head_rcu() 712 * or hlist_del_rcu(), running on this same list. 713 * However, it is perfectly legal to run concurrently with 714 * the _rcu list-traversal primitives, such as 715 * hlist_for_each_entry_rcu(), used to prevent memory-consistency 716 * problems on Alpha CPUs. Regardless of the type of CPU, the 717 * list-traversal primitive must be guarded by rcu_read_lock(). 718 */ 719 static inline void hlist_add_head_rcu(struct hlist_node *n, 720 struct hlist_head *h) 721 { 722 struct hlist_node *first = h->first; 723 n->next = first; 724 n->pprev = &h->first; 725 smp_wmb(); 726 if (first) 727 first->pprev = &n->next; 728 h->first = n; 729 } 730 731 /* next must be != NULL */ 732 static inline void hlist_add_before(struct hlist_node *n, 733 struct hlist_node *next) 734 { 735 n->pprev = next->pprev; 736 n->next = next; 737 next->pprev = &n->next; 738 *(n->pprev) = n; 739 } 740 741 static inline void hlist_add_after(struct hlist_node *n, 742 struct hlist_node *next) 743 { 744 next->next = n->next; 745 n->next = next; 746 next->pprev = &n->next; 747 748 if(next->next) 749 next->next->pprev = &next->next; 750 } 751 752 /** 753 * hlist_add_before_rcu 754 * @n: the new element to add to the hash list. 755 * @next: the existing element to add the new element before. 756 * 757 * Description: 758 * Adds the specified element to the specified hlist 759 * before the specified node while permitting racing traversals. 760 * 761 * The caller must take whatever precautions are necessary 762 * (such as holding appropriate locks) to avoid racing 763 * with another list-mutation primitive, such as hlist_add_head_rcu() 764 * or hlist_del_rcu(), running on this same list. 765 * However, it is perfectly legal to run concurrently with 766 * the _rcu list-traversal primitives, such as 767 * hlist_for_each_entry_rcu(), used to prevent memory-consistency 768 * problems on Alpha CPUs. 769 */ 770 static inline void hlist_add_before_rcu(struct hlist_node *n, 771 struct hlist_node *next) 772 { 773 n->pprev = next->pprev; 774 n->next = next; 775 smp_wmb(); 776 next->pprev = &n->next; 777 *(n->pprev) = n; 778 } 779 780 /** 781 * hlist_add_after_rcu 782 * @prev: the existing element to add the new element after. 783 * @n: the new element to add to the hash list. 784 * 785 * Description: 786 * Adds the specified element to the specified hlist 787 * after the specified node while permitting racing traversals. 788 * 789 * The caller must take whatever precautions are necessary 790 * (such as holding appropriate locks) to avoid racing 791 * with another list-mutation primitive, such as hlist_add_head_rcu() 792 * or hlist_del_rcu(), running on this same list. 793 * However, it is perfectly legal to run concurrently with 794 * the _rcu list-traversal primitives, such as 795 * hlist_for_each_entry_rcu(), used to prevent memory-consistency 796 * problems on Alpha CPUs. 797 */ 798 static inline void hlist_add_after_rcu(struct hlist_node *prev, 799 struct hlist_node *n) 800 { 801 n->next = prev->next; 802 n->pprev = &prev->next; 803 smp_wmb(); 804 prev->next = n; 805 if (n->next) 806 n->next->pprev = &n->next; 807 } 808 809 #define hlist_entry(ptr, type, member) container_of(ptr,type,member) 810 811 #define hlist_for_each(pos, head) \ 812 for (pos = (head)->first; pos && ({ prefetch(pos->next); 1; }); \ 813 pos = pos->next) 814 815 #define hlist_for_each_safe(pos, n, head) \ 816 for (pos = (head)->first; pos && ({ n = pos->next; 1; }); \ 817 pos = n) 818 819 /** 820 * hlist_for_each_entry - iterate over list of given type 821 * @tpos: the type * to use as a loop cursor. 822 * @pos: the &struct hlist_node to use as a loop cursor. 823 * @head: the head for your list. 824 * @member: the name of the hlist_node within the struct. 825 */ 826 #define hlist_for_each_entry(tpos, pos, head, member) \ 827 for (pos = (head)->first; \ 828 pos && ({ prefetch(pos->next); 1;}) && \ 829 ({ tpos = hlist_entry(pos, typeof(*tpos), member); 1;}); \ 830 pos = pos->next) 831 832 /** 833 * hlist_for_each_entry_continue - iterate over a hlist continuing after current point 834 * @tpos: the type * to use as a loop cursor. 835 * @pos: the &struct hlist_node to use as a loop cursor. 836 * @member: the name of the hlist_node within the struct. 837 */ 838 #define hlist_for_each_entry_continue(tpos, pos, member) \ 839 for (pos = (pos)->next; \ 840 pos && ({ prefetch(pos->next); 1;}) && \ 841 ({ tpos = hlist_entry(pos, typeof(*tpos), member); 1;}); \ 842 pos = pos->next) 843 844 /** 845 * hlist_for_each_entry_from - iterate over a hlist continuing from current point 846 * @tpos: the type * to use as a loop cursor. 847 * @pos: the &struct hlist_node to use as a loop cursor. 848 * @member: the name of the hlist_node within the struct. 849 */ 850 #define hlist_for_each_entry_from(tpos, pos, member) \ 851 for (; pos && ({ prefetch(pos->next); 1;}) && \ 852 ({ tpos = hlist_entry(pos, typeof(*tpos), member); 1;}); \ 853 pos = pos->next) 854 855 /** 856 * hlist_for_each_entry_safe - iterate over list of given type safe against removal of list entry 857 * @tpos: the type * to use as a loop cursor. 858 * @pos: the &struct hlist_node to use as a loop cursor. 859 * @n: another &struct hlist_node to use as temporary storage 860 * @head: the head for your list. 861 * @member: the name of the hlist_node within the struct. 862 */ 863 #define hlist_for_each_entry_safe(tpos, pos, n, head, member) \ 864 for (pos = (head)->first; \ 865 pos && ({ n = pos->next; 1; }) && \ 866 ({ tpos = hlist_entry(pos, typeof(*tpos), member); 1;}); \ 867 pos = n) 868 869 /** 870 * hlist_for_each_entry_rcu - iterate over rcu list of given type 871 * @tpos: the type * to use as a loop cursor. 872 * @pos: the &struct hlist_node to use as a loop cursor. 873 * @head: the head for your list. 874 * @member: the name of the hlist_node within the struct. 875 * 876 * This list-traversal primitive may safely run concurrently with 877 * the _rcu list-mutation primitives such as hlist_add_head_rcu() 878 * as long as the traversal is guarded by rcu_read_lock(). 879 */ 880 #define hlist_for_each_entry_rcu(tpos, pos, head, member) \ 881 for (pos = (head)->first; \ 882 rcu_dereference(pos) && ({ prefetch(pos->next); 1;}) && \ 883 ({ tpos = hlist_entry(pos, typeof(*tpos), member); 1;}); \ 884 pos = pos->next) 885 886 #else 887 #warning "don't include kernel headers in userspace" 888 #endif /* __KERNEL__ */ 889 #endif 890