include/list.h

   1 #ifndef _LINUX_LIST_H
   2 #define _LINUX_LIST_H
   3
   4 #include <stddef.h>
   5 /**
   6  * container_of - cast a member of a structure out to the containing structure
   7  * @ptr:        the pointer to the member.
   8  * @type:       the type of the container struct this is embedded in.
   9  * @member:     the name of the member within the struct.
  10  *
  11  */
  12 /*#ifndef container_of
  13 #define container_of(ptr, type, member) (                       \
  14         (type *)( (char *)ptr - offsetof(type,member) ))
  15 #endif
  16 */
  17
  18 /*
  19  * Simple doubly linked list implementation.
  20  *
  21  * Some of the internal functions ("__xxx") are useful when
  22  * manipulating whole lists rather than single entries, as
  23  * sometimes we already know the next/prev entries and we can
  24  * generate better code by using them directly rather than
  25  * using the generic single-entry routines.
  26  */
  27
  28 struct list_head {
  29         struct list_head *next, *prev;
  30 };
  31
  32 #define LIST_HEAD_INIT(name) { &(name), &(name) }
  33
  34 #define LIST_HEAD(name) \
  35         struct list_head name = LIST_HEAD_INIT(name)
  36
  37 static inline void INIT_LIST_HEAD(struct list_head *list)
  38 {
  39         list->next = list;
  40         list->prev = list;
  41 }
  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  */
  49 static inline void __list_add(struct list_head *new,
  50                               struct list_head *prev,
  51                               struct list_head *next)
  52 {
  53         next->prev = new;
  54         new->next = next;
  55         new->prev = prev;
  56         prev->next = new;
  57 }
  58
  59 /**
  60  * list_add - add a new entry
  61  * @new: new entry to be added
  62  * @head: list head to add it after
  63  *
  64  * Insert a new entry after the specified head.
  65  * This is good for implementing stacks.
  66  */
  67 static inline void list_add(struct list_head *new, struct list_head *head)
  68 {
  69         __list_add(new, head, head->next);
  70 }
  71
  72
  73 /**
  74  * list_add_tail - add a new entry
  75  * @new: new entry to be added
  76  * @head: list head to add it before
  77  *
  78  * Insert a new entry before the specified head.
  79  * This is useful for implementing queues.
  80  */
  81 static inline void list_add_tail(struct list_head *new, struct list_head *head)
  82 {
  83         __list_add(new, head->prev, head);
  84 }
  85
  86
  87 /*
  88  * Delete a list entry by making the prev/next entries
  89  * point to each other.
  90  *
  91  * This is only for internal list manipulation where we know
  92  * the prev/next entries already!
  93  */
  94 static inline void __list_del(struct list_head * prev, struct list_head * next)
  95 {
  96         next->prev = prev;
  97         prev->next = next;
  98 }
  99
 100 /**
 101  * list_del - deletes entry from list.
 102  * @entry: the element to delete from the list.
 103  * Note: list_empty() on entry does not return true after this, the entry is
 104  * in an undefined state.
 105  */
 106 static inline void list_del(struct list_head *entry)
 107 {
 108         __list_del(entry->prev, entry->next);
 109         entry->next = NULL;
 110         entry->prev = NULL;
 111 }
 112
 113 /**
 114  * list_replace - replace old entry by new one
 115  * @old : the element to be replaced
 116  * @new : the new element to insert
 117  *
 118  * If @old was empty, it will be overwritten.
 119  */
 120 static inline void list_replace(struct list_head *old,
 121                                 struct list_head *new)
 122 {
 123         new->next = old->next;
 124         new->next->prev = new;
 125         new->prev = old->prev;
 126         new->prev->next = new;
 127 }
 128
 129 static inline void list_replace_init(struct list_head *old,
 130                                         struct list_head *new)
 131 {
 132         list_replace(old, new);
 133         INIT_LIST_HEAD(old);
 134 }
 135
 136 /**
 137  * list_del_init - deletes entry from list and reinitialize it.
 138  * @entry: the element to delete from the list.
 139  */
 140 static inline void list_del_init(struct list_head *entry)
 141 {
 142         __list_del(entry->prev, entry->next);
 143         INIT_LIST_HEAD(entry);
 144 }
 145
 146 /**
 147  * list_move - delete from one list and add as another's head
 148  * @list: the entry to move
 149  * @head: the head that will precede our entry
 150  */
 151 static inline void list_move(struct list_head *list, struct list_head *head)
 152 {
 153         __list_del(list->prev, list->next);
 154         list_add(list, head);
 155 }
 156
 157 /**
 158  * list_move_tail - delete from one list and add as another's tail
 159  * @list: the entry to move
 160  * @head: the head that will follow our entry
 161  */
 162 static inline void list_move_tail(struct list_head *list,
 163                                   struct list_head *head)
 164 {
 165         __list_del(list->prev, list->next);
 166         list_add_tail(list, head);
 167 }
 168
 169 /**
 170  * list_is_last - tests whether @list is the last entry in list @head
 171  * @list: the entry to test
 172  * @head: the head of the list
 173  */
 174 static inline int list_is_last(const struct list_head *list,
 175                                 const struct list_head *head)
 176 {
 177         return list->next == head;
 178 }
 179
 180 /**
 181  * list_empty - tests whether a list is empty
 182  * @head: the list to test.
 183  */
 184 static inline int list_empty(const struct list_head *head)
 185 {
 186         return head->next == head;
 187 }
 188
 189 /**
 190  * list_count
 191  * @head: the list to test.
 192  */
 193 static inline int list_count(const struct list_head *head)
 194 {
 195         int i = 0;
 196         const struct list_head *p = head->next;
 197         while(p != head)
 198         {
 199                 p = p->next;
 200                 i++;
 201         }
 202         return i;
 203 }
 204
 205 /**
 206  * list_empty_careful - tests whether a list is empty and not being modified
 207  * @head: the list to test
 208  *
 209  * Description:
 210  * tests whether a list is empty _and_ checks that no other CPU might be
 211  * in the process of modifying either member (next or prev)
 212  *
 213  * NOTE: using list_empty_careful() without synchronization
 214  * can only be safe if the only activity that can happen
 215  * to the list entry is list_del_init(). Eg. it cannot be used
 216  * if another CPU could re-list_add() it.
 217  */
 218 static inline int list_empty_careful(const struct list_head *head)
 219 {
 220         struct list_head *next = head->next;
 221         return (next == head) && (next == head->prev);
 222 }
 223
 224 static inline void __list_splice(struct list_head *list,
 225                                  struct list_head *head)
 226 {
 227         struct list_head *first = list->next;
 228         struct list_head *last = list->prev;
 229         struct list_head *at = head->next;
 230
 231         first->prev = head;
 232         head->next = first;
 233
 234         last->next = at;
 235         at->prev = last;
 236 }
 237
 238 /**
 239  * list_splice - join two lists
 240  * @list: the new list to add.
 241  * @head: the place to add it in the first list.
 242  */
 243 static inline void list_splice(struct list_head *list, struct list_head *head)
 244 {
 245         if (!list_empty(list))
 246                 __list_splice(list, head);
 247 }
 248
 249 /**
 250  * list_splice_init - join two lists and reinitialise the emptied list.
 251  * @list: the new list to add.
 252  * @head: the place to add it in the first list.
 253  *
 254  * The list at @list is reinitialised
 255  */
 256 static inline void list_splice_init(struct list_head *list,
 257                                     struct list_head *head)
 258 {
 259         if (!list_empty(list)) {
 260                 __list_splice(list, head);
 261                 INIT_LIST_HEAD(list);
 262         }
 263 }
 264
 265 /**
 266  * list_entry - get the struct for this entry
 267  * @ptr:        the &struct list_head pointer.
 268  * @type:       the type of the struct this is embedded in.
 269  * @member:     the name of the list_struct within the struct.
 270  */
 271 #define list_entry(ptr, type, member) \
 272         container_of(ptr, type, member)
 273
 274 /**
 275  * list_first_entry - get the first element from a list
 276  * @ptr:        the list head to take the element from.
 277  * @type:       the type of the struct this is embedded in.
 278  * @member:     the name of the list_struct within the struct.
 279  *
 280  * Note, that list is expected to be not empty.
 281  */
 282 #define list_first_entry(ptr, type, member) \
 283         list_entry((ptr)->next, type, member)
 284
 285 /**
 286  * list_for_each        -       iterate over a list
 287  * @pos:        the &struct list_head to use as a loop cursor.
 288  * @head:       the head for your list.
 289  */
 290 #define list_for_each(pos, head) \
 291         for (pos = (head)->next; pos != (head); \
 292                 pos = pos->next)
 293
 294 /**
 295  * __list_for_each      -       iterate over a list
 296  * @pos:        the &struct list_head to use as a loop cursor.
 297  * @head:       the head for your list.
 298  *
 299  * This variant differs from list_for_each() in that it's the
 300  * simplest possible list iteration code, no prefetching is done.
 301  * Use this for code that knows the list to be very short (empty
 302  * or 1 entry) most of the time.
 303  */
 304 #define __list_for_each(pos, head) \
 305         for (pos = (head)->next; pos != (head); pos = pos->next)
 306
 307 /**
 308  * list_for_each_prev   -       iterate over a list backwards
 309  * @pos:        the &struct list_head to use as a loop cursor.
 310  * @head:       the head for your list.
 311  */
 312 #define list_for_each_prev(pos, head) \
 313         for (pos = (head)->prev; pos != (head); \
 314                 pos = pos->prev)
 315
 316 /**
 317  * list_for_each_safe - iterate over a list safe against removal of list entry
 318  * @pos:        the &struct list_head to use as a loop cursor.
 319  * @n:          another &struct list_head to use as temporary storage
 320  * @head:       the head for your list.
 321  */
 322 #define list_for_each_safe(pos, n, head) \
 323         for (pos = (head)->next, n = pos->next; pos != (head); \
 324                 pos = n, n = pos->next)
 325
 326 /**
 327  * list_for_each_prev_safe - iterate over a list backwards safe against removal of list entry
 328  * @pos:        the &struct list_head to use as a loop cursor.
 329  * @n:          another &struct list_head to use as temporary storage
 330  * @head:       the head for your list.
 331  */
 332 #define list_for_each_prev_safe(pos, n, head) \
 333         for (pos = (head)->prev, n = pos->prev; \
 334              pos != (head); \
 335              pos = n, n = pos->prev)
 336
 337 /**
 338  * list_for_each_entry  -       iterate over list of given type
 339  * @pos:        the type * to use as a loop cursor.
 340  * @head:       the head for your list.
 341  * @member:     the name of the list_struct within the struct.
 342  */
 343 #define list_for_each_entry(pos, head, member)                          \
 344         for (pos = list_entry((head)->next, typeof(*pos), member);      \
 345              &pos->member != (head);    \
 346              pos = list_entry(pos->member.next, typeof(*pos), member))
 347
 348 /**
 349  * list_for_each_entry_reverse - iterate backwards over list of given type.
 350  * @pos:        the type * to use as a loop cursor.
 351  * @head:       the head for your list.
 352  * @member:     the name of the list_struct within the struct.
 353  */
 354 #define list_for_each_entry_reverse(pos, head, member)                  \
 355         for (pos = list_entry((head)->prev, typeof(*pos), member);      \
 356              &pos->member != (head);    \
 357              pos = list_entry(pos->member.prev, typeof(*pos), member))
 358
 359 /**
 360  * list_prepare_entry - prepare a pos entry for use in list_for_each_entry_continue()
 361  * @pos:        the type * to use as a start point
 362  * @head:       the head of the list
 363  * @member:     the name of the list_struct within the struct.
 364  *
 365  * Prepares a pos entry for use as a start point in list_for_each_entry_continue().
 366  */
 367 #define list_prepare_entry(pos, head, member) \
 368         ((pos) ? : list_entry(head, typeof(*pos), member))
 369
 370 /**
 371  * list_for_each_entry_continue - continue iteration over list of given type
 372  * @pos:        the type * to use as a loop cursor.
 373  * @head:       the head for your list.
 374  * @member:     the name of the list_struct within the struct.
 375  *
 376  * Continue to iterate over list of given type, continuing after
 377  * the current position.
 378  */
 379 #define list_for_each_entry_continue(pos, head, member)                 \
 380         for (pos = list_entry(pos->member.next, typeof(*pos), member);  \
 381              &pos->member != (head);    \
 382              pos = list_entry(pos->member.next, typeof(*pos), member))
 383
 384 /**
 385  * list_for_each_entry_continue_reverse - iterate backwards from the given point
 386  * @pos:        the type * to use as a loop cursor.
 387  * @head:       the head for your list.
 388  * @member:     the name of the list_struct within the struct.
 389  *
 390  * Start to iterate over list of given type backwards, continuing after
 391  * the current position.
 392  */
 393 #define list_for_each_entry_continue_reverse(pos, head, member)         \
 394         for (pos = list_entry(pos->member.prev, typeof(*pos), member);  \
 395              &pos->member != (head);    \
 396              pos = list_entry(pos->member.prev, typeof(*pos), member))
 397
 398 /**
 399  * list_for_each_entry_from - iterate over list of given type from the current point
 400  * @pos:        the type * to use as a loop cursor.
 401  * @head:       the head for your list.
 402  * @member:     the name of the list_struct within the struct.
 403  *
 404  * Iterate over list of given type, continuing from current position.
 405  */
 406 #define list_for_each_entry_from(pos, head, member)                     \
 407         for (; &pos->member != (head);  \
 408              pos = list_entry(pos->member.next, typeof(*pos), member))
 409
 410 /**
 411  * list_for_each_entry_safe - iterate over list of given type safe against removal of list entry
 412  * @pos:        the type * to use as a loop cursor.
 413  * @n:          another type * to use as temporary storage
 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_safe(pos, n, head, member)                  \
 418         for (pos = list_entry((head)->next, typeof(*pos), member),      \
 419                 n = list_entry(pos->member.next, typeof(*pos), member); \
 420              &pos->member != (head);                                    \
 421              pos = n, n = list_entry(n->member.next, typeof(*n), member))
 422
 423 /**
 424  * list_for_each_entry_safe_continue
 425  * @pos:        the type * to use as a loop cursor.
 426  * @n:          another type * to use as temporary storage
 427  * @head:       the head for your list.
 428  * @member:     the name of the list_struct within the struct.
 429  *
 430  * Iterate over list of given type, continuing after current point,
 431  * safe against removal of list entry.
 432  */
 433 #define list_for_each_entry_safe_continue(pos, n, head, member)                 \
 434         for (pos = list_entry(pos->member.next, typeof(*pos), member),          \
 435                 n = list_entry(pos->member.next, typeof(*pos), member);         \
 436              &pos->member != (head);                                            \
 437              pos = n, n = list_entry(n->member.next, typeof(*n), member))
 438
 439 /**
 440  * list_for_each_entry_safe_from
 441  * @pos:        the type * to use as a loop cursor.
 442  * @n:          another type * to use as temporary storage
 443  * @head:       the head for your list.
 444  * @member:     the name of the list_struct within the struct.
 445  *
 446  * Iterate over list of given type from current point, safe against
 447  * removal of list entry.
 448  */
 449 #define list_for_each_entry_safe_from(pos, n, head, member)                     \
 450         for (n = list_entry(pos->member.next, typeof(*pos), member);            \
 451              &pos->member != (head);                                            \
 452              pos = n, n = list_entry(n->member.next, typeof(*n), member))
 453
 454 /**
 455  * list_for_each_entry_safe_reverse
 456  * @pos:        the type * to use as a loop cursor.
 457  * @n:          another type * to use as temporary storage
 458  * @head:       the head for your list.
 459  * @member:     the name of the list_struct within the struct.
 460  *
 461  * Iterate backwards over list of given type, safe against removal
 462  * of list entry.
 463  */
 464 #define list_for_each_entry_safe_reverse(pos, n, head, member)          \
 465         for (pos = list_entry((head)->prev, typeof(*pos), member),      \
 466                 n = list_entry(pos->member.prev, typeof(*pos), member); \
 467              &pos->member != (head);                                    \
 468              pos = n, n = list_entry(n->member.prev, typeof(*n), member))
 469
 470 /*
 471  * Double linked lists with a single pointer list head.
 472  * Mostly useful for hash tables where the two pointer list head is
 473  * too wasteful.
 474  * You lose the ability to access the tail in O(1).
 475  */
 476
 477 struct hlist_head {
 478         struct hlist_node *first;
 479 };
 480
 481 struct hlist_node {
 482         struct hlist_node *next, **pprev;
 483 };
 484
 485 #define HLIST_HEAD_INIT { .first = NULL }
 486 #define HLIST_HEAD(name) struct hlist_head name = {  .first = NULL }
 487 #define INIT_HLIST_HEAD(ptr) ((ptr)->first = NULL)
 488 static inline void INIT_HLIST_NODE(struct hlist_node *h)
 489 {
 490         h->next = NULL;
 491         h->pprev = NULL;
 492 }
 493
 494 static inline int hlist_unhashed(const struct hlist_node *h)
 495 {
 496         return !h->pprev;
 497 }
 498
 499 static inline int hlist_empty(const struct hlist_head *h)
 500 {
 501         return !h->first;
 502 }
 503
 504 static inline void __hlist_del(struct hlist_node *n)
 505 {
 506         struct hlist_node *next = n->next;
 507         struct hlist_node **pprev = n->pprev;
 508         *pprev = next;
 509         if (next)
 510                 next->pprev = pprev;
 511 }
 512
 513 static inline void hlist_del(struct hlist_node *n)
 514 {
 515         __hlist_del(n);
 516         n->next = NULL;
 517         n->pprev = NULL;
 518 }
 519
 520 static inline void hlist_del_init(struct hlist_node *n)
 521 {
 522         if (!hlist_unhashed(n)) {
 523                 __hlist_del(n);
 524                 INIT_HLIST_NODE(n);
 525         }
 526 }
 527
 528
 529 static inline void hlist_add_head(struct hlist_node *n, struct hlist_head *h)
 530 {
 531         struct hlist_node *first = h->first;
 532         n->next = first;
 533         if (first)
 534                 first->pprev = &n->next;
 535         h->first = n;
 536         n->pprev = &h->first;
 537 }
 538
 539
 540 /* next must be != NULL */
 541 static inline void hlist_add_before(struct hlist_node *n,
 542                                         struct hlist_node *next)
 543 {
 544         n->pprev = next->pprev;
 545         n->next = next;
 546         next->pprev = &n->next;
 547         *(n->pprev) = n;
 548 }
 549
 550 static inline void hlist_add_after(struct hlist_node *n,
 551                                         struct hlist_node *next)
 552 {
 553         next->next = n->next;
 554         n->next = next;
 555         next->pprev = &n->next;
 556
 557         if(next->next)
 558                 next->next->pprev  = &next->next;
 559 }
 560
 561 #define hlist_entry(ptr, type, member) container_of(ptr,type,member)
 562
 563 #define hlist_for_each(pos, head) \
 564         for (pos = (head)->first; pos; pos = pos->next)
 565
 566 #define hlist_for_each_safe(pos, n, head) \
 567         for (pos = (head)->first; pos; pos = n)
 568
 569 /**
 570  * hlist_for_each_entry - iterate over list of given type
 571  * @tpos:       the type * to use as a loop cursor.
 572  * @pos:        the &struct hlist_node to use as a loop cursor.
 573  * @head:       the head for your list.
 574  * @member:     the name of the hlist_node within the struct.
 575  */
 576 #define hlist_for_each_entry(tpos, pos, head, member)                    \
 577         for (pos = (head)->first; pos &&                                 \
 578                 ({ tpos = hlist_entry(pos, typeof(*tpos), member); 1;}); \
 579              pos = pos->next)
 580
 581 /**
 582  * hlist_for_each_entry_continue - iterate over a hlist continuing after current point
 583  * @tpos:       the type * to use as a loop cursor.
 584  * @pos:        the &struct hlist_node to use as a loop cursor.
 585  * @member:     the name of the hlist_node within the struct.
 586  */
 587 #define hlist_for_each_entry_continue(tpos, pos, member)                \
 588         for (pos = (pos)->next; pos &&                                  \
 589              ({ tpos = hlist_entry(pos, typeof(*tpos), member); 1;});   \
 590              pos = pos->next)
 591
 592 /**
 593  * hlist_for_each_entry_from - iterate over a hlist continuing from current point
 594  * @tpos:       the type * to use as a loop cursor.
 595  * @pos:        the &struct hlist_node to use as a loop cursor.
 596  * @member:     the name of the hlist_node within the struct.
 597  */
 598 #define hlist_for_each_entry_from(tpos, pos, member)                     \
 599         for (; pos &&                    \
 600                 ({ tpos = hlist_entry(pos, typeof(*tpos), member); 1;}); \
 601              pos = pos->next)
 602
 603 /**
 604  * hlist_for_each_entry_safe - iterate over list of given type safe against removal of list entry
 605  * @tpos:       the type * to use as a loop cursor.
 606  * @pos:        the &struct hlist_node to use as a loop cursor.
 607  * @n:          another &struct hlist_node to use as temporary storage
 608  * @head:       the head for your list.
 609  * @member:     the name of the hlist_node within the struct.
 610  */
 611 #define hlist_for_each_entry_safe(tpos, pos, n, head, member)            \
 612         for (pos = (head)->first;                                        \
 613              pos && ({ n = pos->next; 1; }) &&                           \
 614                 ({ tpos = hlist_entry(pos, typeof(*tpos), member); 1;}); \
 615              pos = n)
 616
 617 #endif