1/* SPDX-License-Identifier: GPL-2.0 */ 2#ifndef _LINUX_RCULIST_H 3#define _LINUX_RCULIST_H 4 5#ifdef __KERNEL__ 6 7/* 8 * RCU-protected list version 9 */ 10#include <linux/list.h> 11#include <linux/rcupdate.h> 12 13/* 14 * Why is there no list_empty_rcu()? Because list_empty() serves this 15 * purpose. The list_empty() function fetches the RCU-protected pointer 16 * and compares it to the address of the list head, but neither dereferences 17 * this pointer itself nor provides this pointer to the caller. Therefore, 18 * it is not necessary to use rcu_dereference(), so that list_empty() can 19 * be used anywhere you would want to use a list_empty_rcu(). 20 */ 21 22/* 23 * INIT_LIST_HEAD_RCU - Initialize a list_head visible to RCU readers 24 * @list: list to be initialized 25 * 26 * You should instead use INIT_LIST_HEAD() for normal initialization and 27 * cleanup tasks, when readers have no access to the list being initialized. 28 * However, if the list being initialized is visible to readers, you 29 * need to keep the compiler from being too mischievous. 30 */ 31static inline void INIT_LIST_HEAD_RCU(struct list_head *list) 32{ 33 WRITE_ONCE(list->next, list); 34 WRITE_ONCE(list->prev, list); 35} 36 37/* 38 * return the ->next pointer of a list_head in an rcu safe 39 * way, we must not access it directly 40 */ 41#define list_next_rcu(list) (*((struct list_head __rcu **)(&(list)->next))) 42 43/* 44 * Insert a new entry between two known consecutive entries. 45 * 46 * This is only for internal list manipulation where we know 47 * the prev/next entries already! 48 */ 49static inline void __list_add_rcu(struct list_head *new, 50 struct list_head *prev, struct list_head *next) 51{ 52 if (!__list_add_valid(new, prev, next)) 53 return; 54 55 new->next = next; 56 new->prev = prev; 57 rcu_assign_pointer(list_next_rcu(prev), new); 58 next->prev = new; 59} 60 61/** 62 * list_add_rcu - add a new entry to rcu-protected list 63 * @new: new entry to be added 64 * @head: list head to add it after 65 * 66 * Insert a new entry after the specified head. 67 * This is good for implementing stacks. 68 * 69 * The caller must take whatever precautions are necessary 70 * (such as holding appropriate locks) to avoid racing 71 * with another list-mutation primitive, such as list_add_rcu() 72 * or list_del_rcu(), running on this same list. 73 * However, it is perfectly legal to run concurrently with 74 * the _rcu list-traversal primitives, such as 75 * list_for_each_entry_rcu(). 76 */ 77static inline void list_add_rcu(struct list_head *new, struct list_head *head) 78{ 79 __list_add_rcu(new, head, head->next); 80} 81 82/** 83 * list_add_tail_rcu - add a new entry to rcu-protected list 84 * @new: new entry to be added 85 * @head: list head to add it before 86 * 87 * Insert a new entry before the specified head. 88 * This is useful for implementing queues. 89 * 90 * The caller must take whatever precautions are necessary 91 * (such as holding appropriate locks) to avoid racing 92 * with another list-mutation primitive, such as list_add_tail_rcu() 93 * or list_del_rcu(), running on this same list. 94 * However, it is perfectly legal to run concurrently with 95 * the _rcu list-traversal primitives, such as 96 * list_for_each_entry_rcu(). 97 */ 98static inline void list_add_tail_rcu(struct list_head *new, 99 struct list_head *head) 100{ 101 __list_add_rcu(new, head->prev, head); 102} 103 104/** 105 * list_del_rcu - deletes entry from list without re-initialization 106 * @entry: the element to delete from the list. 107 * 108 * Note: list_empty() on entry does not return true after this, 109 * the entry is in an undefined state. It is useful for RCU based 110 * lockfree traversal. 111 * 112 * In particular, it means that we can not poison the forward 113 * pointers that may still be used for walking the list. 114 * 115 * The caller must take whatever precautions are necessary 116 * (such as holding appropriate locks) to avoid racing 117 * with another list-mutation primitive, such as list_del_rcu() 118 * or list_add_rcu(), running on this same list. 119 * However, it is perfectly legal to run concurrently with 120 * the _rcu list-traversal primitives, such as 121 * list_for_each_entry_rcu(). 122 * 123 * Note that the caller is not permitted to immediately free 124 * the newly deleted entry. Instead, either synchronize_rcu() 125 * or call_rcu() must be used to defer freeing until an RCU 126 * grace period has elapsed. 127 */ 128static inline void list_del_rcu(struct list_head *entry) 129{ 130 __list_del_entry(entry); 131 entry->prev = LIST_POISON2; 132} 133 134/** 135 * hlist_del_init_rcu - deletes entry from hash list with re-initialization 136 * @n: the element to delete from the hash list. 137 * 138 * Note: list_unhashed() on the node return true after this. It is 139 * useful for RCU based read lockfree traversal if the writer side 140 * must know if the list entry is still hashed or already unhashed. 141 * 142 * In particular, it means that we can not poison the forward pointers 143 * that may still be used for walking the hash list and we can only 144 * zero the pprev pointer so list_unhashed() will return true after 145 * this. 146 * 147 * The caller must take whatever precautions are necessary (such as 148 * holding appropriate locks) to avoid racing with another 149 * list-mutation primitive, such as hlist_add_head_rcu() or 150 * hlist_del_rcu(), running on this same list. However, it is 151 * perfectly legal to run concurrently with the _rcu list-traversal 152 * primitives, such as hlist_for_each_entry_rcu(). 153 */ 154static inline void hlist_del_init_rcu(struct hlist_node *n) 155{ 156 if (!hlist_unhashed(n)) { 157 __hlist_del(n); 158 n->pprev = NULL; 159 } 160} 161 162/** 163 * list_replace_rcu - replace old entry by new one 164 * @old : the element to be replaced 165 * @new : the new element to insert 166 * 167 * The @old entry will be replaced with the @new entry atomically. 168 * Note: @old should not be empty. 169 */ 170static inline void list_replace_rcu(struct list_head *old, 171 struct list_head *new) 172{ 173 new->next = old->next; 174 new->prev = old->prev; 175 rcu_assign_pointer(list_next_rcu(new->prev), new); 176 new->next->prev = new; 177 old->prev = LIST_POISON2; 178} 179 180/** 181 * __list_splice_init_rcu - join an RCU-protected list into an existing list. 182 * @list: the RCU-protected list to splice 183 * @prev: points to the last element of the existing list 184 * @next: points to the first element of the existing list 185 * @sync: function to sync: synchronize_rcu(), synchronize_sched(), ... 186 * 187 * The list pointed to by @prev and @next can be RCU-read traversed 188 * concurrently with this function. 189 * 190 * Note that this function blocks. 191 * 192 * Important note: the caller must take whatever action is necessary to prevent 193 * any other updates to the existing list. In principle, it is possible to 194 * modify the list as soon as sync() begins execution. If this sort of thing 195 * becomes necessary, an alternative version based on call_rcu() could be 196 * created. But only if -really- needed -- there is no shortage of RCU API 197 * members. 198 */ 199static inline void __list_splice_init_rcu(struct list_head *list, 200 struct list_head *prev, 201 struct list_head *next, 202 void (*sync)(void)) 203{ 204 struct list_head *first = list->next; 205 struct list_head *last = list->prev; 206 207 /* 208 * "first" and "last" tracking list, so initialize it. RCU readers 209 * have access to this list, so we must use INIT_LIST_HEAD_RCU() 210 * instead of INIT_LIST_HEAD(). 211 */ 212 213 INIT_LIST_HEAD_RCU(list); 214 215 /* 216 * At this point, the list body still points to the source list. 217 * Wait for any readers to finish using the list before splicing 218 * the list body into the new list. Any new readers will see 219 * an empty list. 220 */ 221 222 sync(); 223 224 /* 225 * Readers are finished with the source list, so perform splice. 226 * The order is important if the new list is global and accessible 227 * to concurrent RCU readers. Note that RCU readers are not 228 * permitted to traverse the prev pointers without excluding 229 * this function. 230 */ 231 232 last->next = next; 233 rcu_assign_pointer(list_next_rcu(prev), first); 234 first->prev = prev; 235 next->prev = last; 236} 237 238/** 239 * list_splice_init_rcu - splice an RCU-protected list into an existing list, 240 * designed for stacks. 241 * @list: the RCU-protected list to splice 242 * @head: the place in the existing list to splice the first list into 243 * @sync: function to sync: synchronize_rcu(), synchronize_sched(), ... 244 */ 245static inline void list_splice_init_rcu(struct list_head *list, 246 struct list_head *head, 247 void (*sync)(void)) 248{ 249 if (!list_empty(list)) 250 __list_splice_init_rcu(list, head, head->next, sync); 251} 252 253/** 254 * list_splice_tail_init_rcu - splice an RCU-protected list into an existing 255 * list, designed for queues. 256 * @list: the RCU-protected list to splice 257 * @head: the place in the existing list to splice the first list into 258 * @sync: function to sync: synchronize_rcu(), synchronize_sched(), ... 259 */ 260static inline void list_splice_tail_init_rcu(struct list_head *list, 261 struct list_head *head, 262 void (*sync)(void)) 263{ 264 if (!list_empty(list)) 265 __list_splice_init_rcu(list, head->prev, head, sync); 266} 267 268/** 269 * list_entry_rcu - get the struct for this entry 270 * @ptr: the &struct list_head pointer. 271 * @type: the type of the struct this is embedded in. 272 * @member: the name of the list_head within the struct. 273 * 274 * This primitive may safely run concurrently with the _rcu list-mutation 275 * primitives such as list_add_rcu() as long as it's guarded by rcu_read_lock(). 276 */ 277#define list_entry_rcu(ptr, type, member) \ 278 container_of(READ_ONCE(ptr), type, member) 279 280/* 281 * Where are list_empty_rcu() and list_first_entry_rcu()? 282 * 283 * Implementing those functions following their counterparts list_empty() and 284 * list_first_entry() is not advisable because they lead to subtle race 285 * conditions as the following snippet shows: 286 * 287 * if (!list_empty_rcu(mylist)) { 288 * struct foo *bar = list_first_entry_rcu(mylist, struct foo, list_member); 289 * do_something(bar); 290 * } 291 * 292 * The list may not be empty when list_empty_rcu checks it, but it may be when 293 * list_first_entry_rcu rereads the ->next pointer. 294 * 295 * Rereading the ->next pointer is not a problem for list_empty() and 296 * list_first_entry() because they would be protected by a lock that blocks 297 * writers. 298 * 299 * See list_first_or_null_rcu for an alternative. 300 */ 301 302/** 303 * list_first_or_null_rcu - get the first element from a list 304 * @ptr: the list head to take the element from. 305 * @type: the type of the struct this is embedded in. 306 * @member: the name of the list_head within the struct. 307 * 308 * Note that if the list is empty, it returns NULL. 309 * 310 * This primitive may safely run concurrently with the _rcu list-mutation 311 * primitives such as list_add_rcu() as long as it's guarded by rcu_read_lock(). 312 */ 313#define list_first_or_null_rcu(ptr, type, member) \ 314({ \ 315 struct list_head *__ptr = (ptr); \ 316 struct list_head *__next = READ_ONCE(__ptr->next); \ 317 likely(__ptr != __next) ? list_entry_rcu(__next, type, member) : NULL; \ 318}) 319 320/** 321 * list_next_or_null_rcu - get the first element from a list 322 * @head: the head for the list. 323 * @ptr: the list head to take the next element from. 324 * @type: the type of the struct this is embedded in. 325 * @member: the name of the list_head within the struct. 326 * 327 * Note that if the ptr is at the end of the list, NULL is returned. 328 * 329 * This primitive may safely run concurrently with the _rcu list-mutation 330 * primitives such as list_add_rcu() as long as it's guarded by rcu_read_lock(). 331 */ 332#define list_next_or_null_rcu(head, ptr, type, member) \ 333({ \ 334 struct list_head *__head = (head); \ 335 struct list_head *__ptr = (ptr); \ 336 struct list_head *__next = READ_ONCE(__ptr->next); \ 337 likely(__next != __head) ? list_entry_rcu(__next, type, \ 338 member) : NULL; \ 339}) 340 341/** 342 * list_for_each_entry_rcu - iterate over rcu list of given type 343 * @pos: the type * to use as a loop cursor. 344 * @head: the head for your list. 345 * @member: the name of the list_head within the struct. 346 * 347 * This list-traversal primitive may safely run concurrently with 348 * the _rcu list-mutation primitives such as list_add_rcu() 349 * as long as the traversal is guarded by rcu_read_lock(). 350 */ 351#define list_for_each_entry_rcu(pos, head, member) \ 352 for (pos = list_entry_rcu((head)->next, typeof(*pos), member); \ 353 &pos->member != (head); \ 354 pos = list_entry_rcu(pos->member.next, typeof(*pos), member)) 355 356/** 357 * list_entry_lockless - get the struct for this entry 358 * @ptr: the &struct list_head pointer. 359 * @type: the type of the struct this is embedded in. 360 * @member: the name of the list_head within the struct. 361 * 362 * This primitive may safely run concurrently with the _rcu list-mutation 363 * primitives such as list_add_rcu(), but requires some implicit RCU 364 * read-side guarding. One example is running within a special 365 * exception-time environment where preemption is disabled and where 366 * lockdep cannot be invoked (in which case updaters must use RCU-sched, 367 * as in synchronize_sched(), call_rcu_sched(), and friends). Another 368 * example is when items are added to the list, but never deleted. 369 */ 370#define list_entry_lockless(ptr, type, member) \ 371 container_of((typeof(ptr))READ_ONCE(ptr), type, member) 372 373/** 374 * list_for_each_entry_lockless - iterate over rcu list of given type 375 * @pos: the type * to use as a loop cursor. 376 * @head: the head for your list. 377 * @member: the name of the list_struct within the struct. 378 * 379 * This primitive may safely run concurrently with the _rcu list-mutation 380 * primitives such as list_add_rcu(), but requires some implicit RCU 381 * read-side guarding. One example is running within a special 382 * exception-time environment where preemption is disabled and where 383 * lockdep cannot be invoked (in which case updaters must use RCU-sched, 384 * as in synchronize_sched(), call_rcu_sched(), and friends). Another 385 * example is when items are added to the list, but never deleted. 386 */ 387#define list_for_each_entry_lockless(pos, head, member) \ 388 for (pos = list_entry_lockless((head)->next, typeof(*pos), member); \ 389 &pos->member != (head); \ 390 pos = list_entry_lockless(pos->member.next, typeof(*pos), member)) 391 392/** 393 * list_for_each_entry_continue_rcu - continue iteration over list of given type 394 * @pos: the type * to use as a loop cursor. 395 * @head: the head for your list. 396 * @member: the name of the list_head within the struct. 397 * 398 * Continue to iterate over list of given type, continuing after 399 * the current position which must have been in the list when the RCU read 400 * lock was taken. 401 * This would typically require either that you obtained the node from a 402 * previous walk of the list in the same RCU read-side critical section, or 403 * that you held some sort of non-RCU reference (such as a reference count) 404 * to keep the node alive *and* in the list. 405 * 406 * This iterator is similar to list_for_each_entry_from_rcu() except 407 * this starts after the given position and that one starts at the given 408 * position. 409 */ 410#define list_for_each_entry_continue_rcu(pos, head, member) \ 411 for (pos = list_entry_rcu(pos->member.next, typeof(*pos), member); \ 412 &pos->member != (head); \ 413 pos = list_entry_rcu(pos->member.next, typeof(*pos), member)) 414 415/** 416 * list_for_each_entry_from_rcu - iterate over a list from current point 417 * @pos: the type * to use as a loop cursor. 418 * @head: the head for your list. 419 * @member: the name of the list_node within the struct. 420 * 421 * Iterate over the tail of a list starting from a given position, 422 * which must have been in the list when the RCU read lock was taken. 423 * This would typically require either that you obtained the node from a 424 * previous walk of the list in the same RCU read-side critical section, or 425 * that you held some sort of non-RCU reference (such as a reference count) 426 * to keep the node alive *and* in the list. 427 * 428 * This iterator is similar to list_for_each_entry_continue_rcu() except 429 * this starts from the given position and that one starts from the position 430 * after the given position. 431 */ 432#define list_for_each_entry_from_rcu(pos, head, member) \ 433 for (; &(pos)->member != (head); \ 434 pos = list_entry_rcu(pos->member.next, typeof(*(pos)), member)) 435 436/** 437 * hlist_del_rcu - deletes entry from hash list without re-initialization 438 * @n: the element to delete from the hash list. 439 * 440 * Note: list_unhashed() on entry does not return true after this, 441 * the entry is in an undefined state. It is useful for RCU based 442 * lockfree traversal. 443 * 444 * In particular, it means that we can not poison the forward 445 * pointers that may still be used for walking the hash list. 446 * 447 * The caller must take whatever precautions are necessary 448 * (such as holding appropriate locks) to avoid racing 449 * with another list-mutation primitive, such as hlist_add_head_rcu() 450 * or hlist_del_rcu(), running on this same list. 451 * However, it is perfectly legal to run concurrently with 452 * the _rcu list-traversal primitives, such as 453 * hlist_for_each_entry(). 454 */ 455static inline void hlist_del_rcu(struct hlist_node *n) 456{ 457 __hlist_del(n); 458 n->pprev = LIST_POISON2; 459} 460 461/** 462 * hlist_replace_rcu - replace old entry by new one 463 * @old : the element to be replaced 464 * @new : the new element to insert 465 * 466 * The @old entry will be replaced with the @new entry atomically. 467 */ 468static inline void hlist_replace_rcu(struct hlist_node *old, 469 struct hlist_node *new) 470{ 471 struct hlist_node *next = old->next; 472 473 new->next = next; 474 new->pprev = old->pprev; 475 rcu_assign_pointer(*(struct hlist_node __rcu **)new->pprev, new); 476 if (next) 477 new->next->pprev = &new->next; 478 old->pprev = LIST_POISON2; 479} 480 481/* 482 * return the first or the next element in an RCU protected hlist 483 */ 484#define hlist_first_rcu(head) (*((struct hlist_node __rcu **)(&(head)->first))) 485#define hlist_next_rcu(node) (*((struct hlist_node __rcu **)(&(node)->next))) 486#define hlist_pprev_rcu(node) (*((struct hlist_node __rcu **)((node)->pprev))) 487 488/** 489 * hlist_add_head_rcu 490 * @n: the element to add to the hash list. 491 * @h: the list to add to. 492 * 493 * Description: 494 * Adds the specified element to the specified hlist, 495 * while permitting racing traversals. 496 * 497 * The caller must take whatever precautions are necessary 498 * (such as holding appropriate locks) to avoid racing 499 * with another list-mutation primitive, such as hlist_add_head_rcu() 500 * or hlist_del_rcu(), running on this same list. 501 * However, it is perfectly legal to run concurrently with 502 * the _rcu list-traversal primitives, such as 503 * hlist_for_each_entry_rcu(), used to prevent memory-consistency 504 * problems on Alpha CPUs. Regardless of the type of CPU, the 505 * list-traversal primitive must be guarded by rcu_read_lock(). 506 */ 507static inline void hlist_add_head_rcu(struct hlist_node *n, 508 struct hlist_head *h) 509{ 510 struct hlist_node *first = h->first; 511 512 n->next = first; 513 n->pprev = &h->first; 514 rcu_assign_pointer(hlist_first_rcu(h), n); 515 if (first) 516 first->pprev = &n->next; 517} 518 519/** 520 * hlist_add_tail_rcu 521 * @n: the element to add to the hash list. 522 * @h: the list to add to. 523 * 524 * Description: 525 * Adds the specified element to the specified hlist, 526 * while permitting racing traversals. 527 * 528 * The caller must take whatever precautions are necessary 529 * (such as holding appropriate locks) to avoid racing 530 * with another list-mutation primitive, such as hlist_add_head_rcu() 531 * or hlist_del_rcu(), running on this same list. 532 * However, it is perfectly legal to run concurrently with 533 * the _rcu list-traversal primitives, such as 534 * hlist_for_each_entry_rcu(), used to prevent memory-consistency 535 * problems on Alpha CPUs. Regardless of the type of CPU, the 536 * list-traversal primitive must be guarded by rcu_read_lock(). 537 */ 538static inline void hlist_add_tail_rcu(struct hlist_node *n, 539 struct hlist_head *h) 540{ 541 struct hlist_node *i, *last = NULL; 542 543 /* Note: write side code, so rcu accessors are not needed. */ 544 for (i = h->first; i; i = i->next) 545 last = i; 546 547 if (last) { 548 n->next = last->next; 549 n->pprev = &last->next; 550 rcu_assign_pointer(hlist_next_rcu(last), n); 551 } else { 552 hlist_add_head_rcu(n, h); 553 } 554} 555 556/** 557 * hlist_add_before_rcu 558 * @n: the new element to add to the hash list. 559 * @next: the existing element to add the new element before. 560 * 561 * Description: 562 * Adds the specified element to the specified hlist 563 * before the specified node while permitting racing traversals. 564 * 565 * The caller must take whatever precautions are necessary 566 * (such as holding appropriate locks) to avoid racing 567 * with another list-mutation primitive, such as hlist_add_head_rcu() 568 * or hlist_del_rcu(), running on this same list. 569 * However, it is perfectly legal to run concurrently with 570 * the _rcu list-traversal primitives, such as 571 * hlist_for_each_entry_rcu(), used to prevent memory-consistency 572 * problems on Alpha CPUs. 573 */ 574static inline void hlist_add_before_rcu(struct hlist_node *n, 575 struct hlist_node *next) 576{ 577 n->pprev = next->pprev; 578 n->next = next; 579 rcu_assign_pointer(hlist_pprev_rcu(n), n); 580 next->pprev = &n->next; 581} 582 583/** 584 * hlist_add_behind_rcu 585 * @n: the new element to add to the hash list. 586 * @prev: the existing element to add the new element after. 587 * 588 * Description: 589 * Adds the specified element to the specified hlist 590 * after the specified node while permitting racing traversals. 591 * 592 * The caller must take whatever precautions are necessary 593 * (such as holding appropriate locks) to avoid racing 594 * with another list-mutation primitive, such as hlist_add_head_rcu() 595 * or hlist_del_rcu(), running on this same list. 596 * However, it is perfectly legal to run concurrently with 597 * the _rcu list-traversal primitives, such as 598 * hlist_for_each_entry_rcu(), used to prevent memory-consistency 599 * problems on Alpha CPUs. 600 */ 601static inline void hlist_add_behind_rcu(struct hlist_node *n, 602 struct hlist_node *prev) 603{ 604 n->next = prev->next; 605 n->pprev = &prev->next; 606 rcu_assign_pointer(hlist_next_rcu(prev), n); 607 if (n->next) 608 n->next->pprev = &n->next; 609} 610 611#define __hlist_for_each_rcu(pos, head) \ 612 for (pos = rcu_dereference(hlist_first_rcu(head)); \ 613 pos; \ 614 pos = rcu_dereference(hlist_next_rcu(pos))) 615 616/** 617 * hlist_for_each_entry_rcu - iterate over rcu list of given type 618 * @pos: the type * to use as a loop cursor. 619 * @head: the head for your list. 620 * @member: the name of the hlist_node within the struct. 621 * 622 * This list-traversal primitive may safely run concurrently with 623 * the _rcu list-mutation primitives such as hlist_add_head_rcu() 624 * as long as the traversal is guarded by rcu_read_lock(). 625 */ 626#define hlist_for_each_entry_rcu(pos, head, member) \ 627 for (pos = hlist_entry_safe (rcu_dereference_raw(hlist_first_rcu(head)),\ 628 typeof(*(pos)), member); \ 629 pos; \ 630 pos = hlist_entry_safe(rcu_dereference_raw(hlist_next_rcu(\ 631 &(pos)->member)), typeof(*(pos)), member)) 632 633/** 634 * hlist_for_each_entry_rcu_notrace - iterate over rcu list of given type (for tracing) 635 * @pos: the type * to use as a loop cursor. 636 * @head: the head for your list. 637 * @member: the name of the hlist_node within the struct. 638 * 639 * This list-traversal primitive may safely run concurrently with 640 * the _rcu list-mutation primitives such as hlist_add_head_rcu() 641 * as long as the traversal is guarded by rcu_read_lock(). 642 * 643 * This is the same as hlist_for_each_entry_rcu() except that it does 644 * not do any RCU debugging or tracing. 645 */ 646#define hlist_for_each_entry_rcu_notrace(pos, head, member) \ 647 for (pos = hlist_entry_safe (rcu_dereference_raw_notrace(hlist_first_rcu(head)),\ 648 typeof(*(pos)), member); \ 649 pos; \ 650 pos = hlist_entry_safe(rcu_dereference_raw_notrace(hlist_next_rcu(\ 651 &(pos)->member)), typeof(*(pos)), member)) 652 653/** 654 * hlist_for_each_entry_rcu_bh - iterate over rcu list of given type 655 * @pos: the type * to use as a loop cursor. 656 * @head: the head for your list. 657 * @member: the name of the hlist_node within the struct. 658 * 659 * This list-traversal primitive may safely run concurrently with 660 * the _rcu list-mutation primitives such as hlist_add_head_rcu() 661 * as long as the traversal is guarded by rcu_read_lock(). 662 */ 663#define hlist_for_each_entry_rcu_bh(pos, head, member) \ 664 for (pos = hlist_entry_safe(rcu_dereference_bh(hlist_first_rcu(head)),\ 665 typeof(*(pos)), member); \ 666 pos; \ 667 pos = hlist_entry_safe(rcu_dereference_bh(hlist_next_rcu(\ 668 &(pos)->member)), typeof(*(pos)), member)) 669 670/** 671 * hlist_for_each_entry_continue_rcu - iterate over a hlist continuing after current point 672 * @pos: the type * to use as a loop cursor. 673 * @member: the name of the hlist_node within the struct. 674 */ 675#define hlist_for_each_entry_continue_rcu(pos, member) \ 676 for (pos = hlist_entry_safe(rcu_dereference_raw(hlist_next_rcu( \ 677 &(pos)->member)), typeof(*(pos)), member); \ 678 pos; \ 679 pos = hlist_entry_safe(rcu_dereference_raw(hlist_next_rcu( \ 680 &(pos)->member)), typeof(*(pos)), member)) 681 682/** 683 * hlist_for_each_entry_continue_rcu_bh - iterate over a hlist continuing after current point 684 * @pos: the type * to use as a loop cursor. 685 * @member: the name of the hlist_node within the struct. 686 */ 687#define hlist_for_each_entry_continue_rcu_bh(pos, member) \ 688 for (pos = hlist_entry_safe(rcu_dereference_bh(hlist_next_rcu( \ 689 &(pos)->member)), typeof(*(pos)), member); \ 690 pos; \ 691 pos = hlist_entry_safe(rcu_dereference_bh(hlist_next_rcu( \ 692 &(pos)->member)), typeof(*(pos)), member)) 693 694/** 695 * hlist_for_each_entry_from_rcu - iterate over a hlist continuing from current point 696 * @pos: the type * to use as a loop cursor. 697 * @member: the name of the hlist_node within the struct. 698 */ 699#define hlist_for_each_entry_from_rcu(pos, member) \ 700 for (; pos; \ 701 pos = hlist_entry_safe(rcu_dereference_raw(hlist_next_rcu( \ 702 &(pos)->member)), typeof(*(pos)), member)) 703 704#endif /* __KERNEL__ */ 705#endif 706