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_first - tests whether @list is the first entry in list @head
 171  * @list: the entry to test
 172  * @head: the head of the list
 173  */
 174 static inline int list_is_first(const struct list_head *list,
 175                                 const struct list_head *head)
 176 {
 177         return list->prev == head;
 178 }
 179
 180 /**
 181  * list_is_last - tests whether @list is the last entry in list @head
 182  * @list: the entry to test
 183  * @head: the head of the list
 184  */
 185 static inline int list_is_last(const struct list_head *list,
 186                                 const struct list_head *head)
 187 {
 188         return list->next == head;
 189 }
 190
 191 /**
 192  * list_empty - tests whether a list is empty
 193  * @head: the list to test.
 194  */
 195 static inline int list_empty(const struct list_head *head)
 196 {
 197         return head->next == head;
 198 }
 199
 200 /**
 201  * list_empty_careful - tests whether a list is empty and not being modified
 202  * @head: the list to test
 203  *
 204  * Description:
 205  * tests whether a list is empty _and_ checks that no other CPU might be
 206  * in the process of modifying either member (next or prev)
 207  *
 208  * NOTE: using list_empty_careful() without synchronization
 209  * can only be safe if the only activity that can happen
 210  * to the list entry is list_del_init(). Eg. it cannot be used
 211  * if another CPU could re-list_add() it.
 212  */
 213 static inline int list_empty_careful(const struct list_head *head)
 214 {
 215         struct list_head *next = head->next;
 216         return (next == head) && (next == head->prev);
 217 }
 218
 219 static inline void __list_splice(struct list_head *list,
 220                                  struct list_head *head)
 221 {
 222         struct list_head *first = list->next;
 223         struct list_head *last = list->prev;
 224         struct list_head *at = head->next;
 225
 226         first->prev = head;
 227         head->next = first;
 228
 229         last->next = at;
 230         at->prev = last;
 231 }
 232
 233 /**
 234  * list_splice - join two lists
 235  * @list: the new list to add.
 236  * @head: the place to add it in the first list.
 237  */
 238 static inline void list_splice(struct list_head *list, struct list_head *head)
 239 {
 240         if (!list_empty(list))
 241                 __list_splice(list, head);
 242 }
 243
 244 /**
 245  * list_splice_init - join two lists and reinitialise the emptied list.
 246  * @list: the new list to add.
 247  * @head: the place to add it in the first list.
 248  *
 249  * The list at @list is reinitialised
 250  */
 251 static inline void list_splice_init(struct list_head *list,
 252                                     struct list_head *head)
 253 {
 254         if (!list_empty(list)) {
 255                 __list_splice(list, head);
 256                 INIT_LIST_HEAD(list);
 257         }
 258 }
 259
 260 /**
 261  * list_entry - get the struct for this entry
 262  * @ptr:        the &struct list_head pointer.
 263  * @type:       the type of the struct this is embedded in.
 264  * @member:     the name of the list_struct within the struct.
 265  */
 266 #define list_entry(ptr, type, member) \
 267         container_of(ptr, type, member)
 268
 269 /**
 270  * list_first_entry - get the first element from a list
 271  * @ptr:        the list head to take the element from.
 272  * @type:       the type of the struct this is embedded in.
 273  * @member:     the name of the list_struct within the struct.
 274  *
 275  * Note, that list is expected to be not empty.
 276  */
 277 #define list_first_entry(ptr, type, member) \
 278         list_entry((ptr)->next, type, member)
 279
 280 /**
 281  * list_for_each        -       iterate over a list
 282  * @pos:        the &struct list_head to use as a loop cursor.
 283  * @head:       the head for your list.
 284  */
 285 #define list_for_each(pos, head) \
 286         for (pos = (head)->next; pos != (head); \
 287                 pos = pos->next)
 288
 289 /**
 290  * __list_for_each      -       iterate over a list
 291  * @pos:        the &struct list_head to use as a loop cursor.
 292  * @head:       the head for your list.
 293  *
 294  * This variant differs from list_for_each() in that it's the
 295  * simplest possible list iteration code, no prefetching is done.
 296  * Use this for code that knows the list to be very short (empty
 297  * or 1 entry) most of the time.
 298  */
 299 #define __list_for_each(pos, head) \
 300         for (pos = (head)->next; pos != (head); pos = pos->next)
 301
 302 /**
 303  * list_for_each_prev   -       iterate over a list backwards
 304  * @pos:        the &struct list_head to use as a loop cursor.
 305  * @head:       the head for your list.
 306  */
 307 #define list_for_each_prev(pos, head) \
 308         for (pos = (head)->prev; pos != (head); \
 309                 pos = pos->prev)
 310
 311 /**
 312  * list_for_each_safe - iterate over a list safe against removal of list entry
 313  * @pos:        the &struct list_head to use as a loop cursor.
 314  * @n:          another &struct list_head to use as temporary storage
 315  * @head:       the head for your list.
 316  */
 317 #define list_for_each_safe(pos, n, head) \
 318         for (pos = (head)->next, n = pos->next; pos != (head); \
 319                 pos = n, n = pos->next)
 320
 321 /**
 322  * list_for_each_prev_safe - iterate over a list backwards safe against removal of list entry
 323  * @pos:        the &struct list_head to use as a loop cursor.
 324  * @n:          another &struct list_head to use as temporary storage
 325  * @head:       the head for your list.
 326  */
 327 #define list_for_each_prev_safe(pos, n, head) \
 328         for (pos = (head)->prev, n = pos->prev; \
 329              pos != (head); \
 330              pos = n, n = pos->prev)
 331
 332 /**
 333  * list_for_each_entry  -       iterate over list of given type
 334  * @pos:        the type * to use as a loop cursor.
 335  * @head:       the head for your list.
 336  * @member:     the name of the list_struct within the struct.
 337  */
 338 #define list_for_each_entry(pos, head, member)                          \
 339         for (pos = list_entry((head)->next, typeof(*pos), member);      \
 340              &pos->member != (head);    \
 341              pos = list_entry(pos->member.next, typeof(*pos), member))
 342
 343 /**
 344  * list_for_each_entry_reverse - iterate backwards over list of given type.
 345  * @pos:        the type * to use as a loop cursor.
 346  * @head:       the head for your list.
 347  * @member:     the name of the list_struct within the struct.
 348  */
 349 #define list_for_each_entry_reverse(pos, head, member)                  \
 350         for (pos = list_entry((head)->prev, typeof(*pos), member);      \
 351              &pos->member != (head);    \
 352              pos = list_entry(pos->member.prev, typeof(*pos), member))
 353
 354 /**
 355  * list_prepare_entry - prepare a pos entry for use in list_for_each_entry_continue()
 356  * @pos:        the type * to use as a start point
 357  * @head:       the head of the list
 358  * @member:     the name of the list_struct within the struct.
 359  *
 360  * Prepares a pos entry for use as a start point in list_for_each_entry_continue().
 361  */
 362 #define list_prepare_entry(pos, head, member) \
 363         ((pos) ? : list_entry(head, typeof(*pos), member))
 364
 365 /**
 366  * list_for_each_entry_continue - continue iteration over list of given type
 367  * @pos:        the type * to use as a loop cursor.
 368  * @head:       the head for your list.
 369  * @member:     the name of the list_struct within the struct.
 370  *
 371  * Continue to iterate over list of given type, continuing after
 372  * the current position.
 373  */
 374 #define list_for_each_entry_continue(pos, head, member)                 \
 375         for (pos = list_entry(pos->member.next, typeof(*pos), member);  \
 376              &pos->member != (head);    \
 377              pos = list_entry(pos->member.next, typeof(*pos), member))
 378
 379 /**
 380  * list_for_each_entry_continue_reverse - iterate backwards from the given point
 381  * @pos:        the type * to use as a loop cursor.
 382  * @head:       the head for your list.
 383  * @member:     the name of the list_struct within the struct.
 384  *
 385  * Start to iterate over list of given type backwards, continuing after
 386  * the current position.
 387  */
 388 #define list_for_each_entry_continue_reverse(pos, head, member)         \
 389         for (pos = list_entry(pos->member.prev, typeof(*pos), member);  \
 390              &pos->member != (head);    \
 391              pos = list_entry(pos->member.prev, typeof(*pos), member))
 392
 393 /**
 394  * list_for_each_entry_from - iterate over list of given type from the current point
 395  * @pos:        the type * to use as a loop cursor.
 396  * @head:       the head for your list.
 397  * @member:     the name of the list_struct within the struct.
 398  *
 399  * Iterate over list of given type, continuing from current position.
 400  */
 401 #define list_for_each_entry_from(pos, head, member)                     \
 402         for (; &pos->member != (head);  \
 403              pos = list_entry(pos->member.next, typeof(*pos), member))
 404
 405 /**
 406  * list_for_each_entry_safe - iterate over list of given type safe against removal of list entry
 407  * @pos:        the type * to use as a loop cursor.
 408  * @n:          another type * to use as temporary storage
 409  * @head:       the head for your list.
 410  * @member:     the name of the list_struct within the struct.
 411  */
 412 #define list_for_each_entry_safe(pos, n, head, member)                  \
 413         for (pos = list_entry((head)->next, typeof(*pos), member),      \
 414                 n = list_entry(pos->member.next, typeof(*pos), member); \
 415              &pos->member != (head);                                    \
 416              pos = n, n = list_entry(n->member.next, typeof(*n), member))
 417
 418 /**
 419  * list_for_each_entry_safe_continue
 420  * @pos:        the type * to use as a loop cursor.
 421  * @n:          another type * to use as temporary storage
 422  * @head:       the head for your list.
 423  * @member:     the name of the list_struct within the struct.
 424  *
 425  * Iterate over list of given type, continuing after current point,
 426  * safe against removal of list entry.
 427  */
 428 #define list_for_each_entry_safe_continue(pos, n, head, member)                 \
 429         for (pos = list_entry(pos->member.next, typeof(*pos), member),          \
 430                 n = list_entry(pos->member.next, typeof(*pos), member);         \
 431              &pos->member != (head);                                            \
 432              pos = n, n = list_entry(n->member.next, typeof(*n), member))
 433
 434 /**
 435  * list_for_each_entry_safe_from
 436  * @pos:        the type * to use as a loop cursor.
 437  * @n:          another type * to use as temporary storage
 438  * @head:       the head for your list.
 439  * @member:     the name of the list_struct within the struct.
 440  *
 441  * Iterate over list of given type from current point, safe against
 442  * removal of list entry.
 443  */
 444 #define list_for_each_entry_safe_from(pos, n, head, member)                     \
 445         for (n = list_entry(pos->member.next, typeof(*pos), member);            \
 446              &pos->member != (head);                                            \
 447              pos = n, n = list_entry(n->member.next, typeof(*n), member))
 448
 449 /**
 450  * list_for_each_entry_safe_reverse
 451  * @pos:        the type * to use as a loop cursor.
 452  * @n:          another type * to use as temporary storage
 453  * @head:       the head for your list.
 454  * @member:     the name of the list_struct within the struct.
 455  *
 456  * Iterate backwards over list of given type, safe against removal
 457  * of list entry.
 458  */
 459 #define list_for_each_entry_safe_reverse(pos, n, head, member)          \
 460         for (pos = list_entry((head)->prev, typeof(*pos), member),      \
 461                 n = list_entry(pos->member.prev, typeof(*pos), member); \
 462              &pos->member != (head);                                    \
 463              pos = n, n = list_entry(n->member.prev, typeof(*n), member))
 464
 465 #endif