linux-3.5/include/linux/list.h
使用只含指针域的双向循环链表进行链表的操作。
下面是我选取部分list.h中代码：
1 #ifndef _LINUX_LIST_H
2 #define _LINUX_LIST_H
3
4 struct list_head {
5 struct list_head *next, *prev;
6 };
7 /*
8 * Simple doubly linked list implementation.
9 *
10 * Some of the internal functions ("__xxx") are useful when
11 * manipulating whole lists rather than single entries, as
12 * sometimes we already know the next/prev entries and we can
13 * generate better code by using them directly rather than
14 * using the generic single-entry routines.
15 */
16
17 #define LIST_HEAD_INIT(name) { &(name), &(name) }
18
19 #define LIST_HEAD(name) 20 struct list_head name = LIST_HEAD_INIT(name)
21
22 static inline void INIT_LIST_HEAD(struct list_head *list)
23 {
24 list->next = list;
25 list->prev = list;
26 }
27
28 /*
29 * Insert a new entry between two known consecutive entries.
30 *
31 * This is only for internal list manipulation where we know
32 * the prev/next entries already!
33 */
34 #ifndef CONFIG_DEBUG_LIST
35 static inline void __list_add(struct list_head *new,
36 struct list_head *prev,
37 struct list_head *next)
38 {
39 next->prev = new;
40 new->next = next;
41 new->prev = prev;
42 prev->next = new;
43 }
44 #else
45 extern void __list_add(struct list_head *new,
46 struct list_head *prev,
47 struct list_head *next);
48 #endif
49
50 /**
51 * list_add - add a new entry
52 * @new: new entry to be added
53 * @head: list head to add it after
54 *
55 * Insert a new entry after the specified head.
56 * This is good for implementing stacks.
57 */
58 static inline void list_add(struct list_head *new, struct list_head *head)
59 {
60 __list_add(new, head, head->next);
61 }
62
63
64 /**
65 * list_add_tail - add a new entry
66 * @new: new entry to be added
67 * @head: list head to add it before
68 *
69 * Insert a new entry before the specified head.
70 * This is useful for implementing queues.
71 */
72 static inline void list_add_tail(struct list_head *new, struct list_head *head)
73 {
74 __list_add(new, head->prev, head);
75 }
76
77 /*
78 * Delete a list entry by making the prev/next entries
79 * point to each other.
80 *
81 * This is only for internal list manipulation where we know
82 * the prev/next entries already!
83 */
84 static inline void __list_del(struct list_head * prev, struct list_head * next)
85 {
86 next->prev = prev;
87 prev->next = next;
88 }
89
90 /**
91 * list_del - deletes entry from list.
92 * @entry: the element to delete from the list.
93 * Note: list_empty() on entry does not return true after this, the entry is
94 * in an undefined state.
95 */
96 #ifndef CONFIG_DEBUG_LIST
97 static inline void __list_del_entry(struct list_head *entry)
98 {
99 __list_del(entry->prev, entry->next);
100 }
101 #endif
102
103 /**
104 * list_replace - replace old entry by new one
105 * @old : the element to be replaced
106 * @new : the new element to insert
107 *
108 * If @old was empty, it will be overwritten.
109 */
110 static inline void list_replace(struct list_head *old,
111 struct list_head *new)
112 {
113 new->next = old->next;
114 new->next->prev = new;
115 new->prev = old->prev;
116 new->prev->next = new;
117 }
118
119 static inline void list_replace_init(struct list_head *old,
120 struct list_head *new)
121 {
122 list_replace(old, new);
123 INIT_LIST_HEAD(old);
124 }
125
126 /**
127 * list_del_init - deletes entry from list and reinitialize it.
128 * @entry: the element to delete from the list.
129 */
130 static inline void list_del_init(struct list_head *entry)
131 {
132 __list_del_entry(entry);
133 INIT_LIST_HEAD(entry);
134 }
135
136 /**
137 * list_move - delete from one list and add as another‘s head
138 * @list: the entry to move
139 * @head: the head that will precede our entry
140 */
141 static inline void list_move(struct list_head *list, struct list_head *head)
142 {
143 __list_del_entry(list);
144 list_add(list, head);
145 }
146
147 /**
148 * list_move_tail - delete from one list and add as another‘s tail
149 * @list: the entry to move
150 * @head: the head that will follow our entry
151 */
152 static inline void list_move_tail(struct list_head *list,
153 struct list_head *head)
154 {
155 __list_del_entry(list);
156 list_add_tail(list, head);
157 }
158
159 /**
160 * list_is_last - tests whether @list is the last entry in list @head
161 * @list: the entry to test
162 * @head: the head of the list
163 */
164 static inline int list_is_last(const struct list_head *list,
165 const struct list_head *head)
166 {
167 return list->next == head;
168 }
169
170 /**
171 * list_empty - tests whether a list is empty
172 * @head: the list to test.
173 */
174 static inline int list_empty(const struct list_head *head)
175 {
176 return head->next == head;
177 }
178
179 /**
180 * list_empty_careful - tests whether a list is empty and not being modified
181 * @head: the list to test
182 *
183 * Description:
184 * tests whether a list is empty _and_ checks that no other CPU might be
185 * in the process of modifying either member (next or prev)
186 *
187 * NOTE: using list_empty_careful() without synchronization
188 * can only be safe if the only activity that can happen
189 * to the list entry is list_del_init(). Eg. it cannot be used
190 * if another CPU could re-list_add() it.
191 */
192 static inline int list_empty_careful(const struct list_head *head)
193 {
194 struct list_head *next = head->next;
195 return (next == head) && (next == head->prev);
196 }
197
198 /**
199 * list_rotate_left - rotate the list to the left
200 * @head: the head of the list
201 */
202 static inline void list_rotate_left(struct list_head *head)
203 {
204 struct list_head *first;
205
206 if (!list_empty(head)) {
207 first = head->next;
208 list_move_tail(first, head);
209 }
210 }
211
212 /**
213 * list_is_singular - tests whether a list has just one entry.
214 * @head: the list to test.
215 */
216 static inline int list_is_singular(const struct list_head *head)
217 {
218 return !list_empty(head) && (head->next == head->prev);
219 }
220
221 static inline void __list_cut_position(struct list_head *list,
222 struct list_head *head, struct list_head *entry)
223 {
224 struct list_head *new_first = entry->next;
225 list->next = head->next;
226 list->next->prev = list;
227 list->prev = entry;
228 entry->next = list;
229 head->next = new_first;
230 new_first->prev = head;
231 }
232
233 /**
234 * list_cut_position - cut a list into two
235 * @list: a new list to add all removed entries
236 * @head: a list with entries
237 * @entry: an entry within head, could be the head itself
238 * and if so we won‘t cut the list
239 *
240 * This helper moves the initial part of @head, up to and
241 * including @entry, from @head to @list. You should
242 * pass on @entry an element you know is on @head. @list
243 * should be an empty list or a list you do not care about
244 * losing its data.
245 *
246 */
247 static inline void list_cut_position(struct list_head *list,
248 struct list_head *head, struct list_head *entry)
249 {
250 if (list_empty(head))
251 return;
252 if (list_is_singular(head) &&
253 (head->next != entry && head != entry))
254 return;
255 if (entry == head)
256 INIT_LIST_HEAD(list);
257 else
258 __list_cut_position(list, head, entry);
259 }
260
261 static inline void __list_splice(const struct list_head *list,
262 struct list_head *prev,
263 struct list_head *next)
264 {
265 struct list_head *first = list->next;
266 struct list_head *last = list->prev;
267
268 first->prev = prev;
269 prev->next = first;
270
271 last->next = next;
272 next->prev = last;
273 }
274
275 /**
276 * list_splice - join two lists, this is designed for stacks
277 * @list: the new list to add.
278 * @head: the place to add it in the first list.
279 */
280 static inline void list_splice(const struct list_head *list,
281 struct list_head *head)
282 {
283 if (!list_empty(list))
284 __list_splice(list, head, head->next);
285 }
286
287 /**
288 * list_splice_tail - join two lists, each list being a queue
289 * @list: the new list to add.
290 * @head: the place to add it in the first list.
291 */
292 static inline void list_splice_tail(struct list_head *list,
293 struct list_head *head)
294 {
295 if (!list_empty(list))
296 __list_splice(list, head->prev, head);
297 }
298
299 /**
300 * list_splice_init - join two lists and reinitialise the emptied list.
301 * @list: the new list to add.
302 * @head: the place to add it in the first list.
303 *
304 * The list at @list is reinitialised
305 */
306 static inline void list_splice_init(struct list_head *list,
307 struct list_head *head)
308 {
309 if (!list_empty(list)) {
310 __list_splice(list, head, head->next);
311 INIT_LIST_HEAD(list);
312 }
313 }
314
315 /**
316 * list_splice_tail_init - join two lists and reinitialise the emptied list
317 * @list: the new list to add.
318 * @head: the place to add it in the first list.
319 *
320 * Each of the lists is a queue.
321 * The list at @list is reinitialised
322 */
323 static inline void list_splice_tail_init(struct list_head *list,
324 struct list_head *head)
325 {
326 if (!list_empty(list)) {
327 __list_splice(list, head->prev, head);
328 INIT_LIST_HEAD(list);
329 }
330 }
331
332 /**
333 * list_entry - get the struct for this entry
334 * @ptr: the &struct list_head pointer.
335 * @type: the type of the struct this is embedded in.
336 * @member: the name of the list_struct within the struct.
337 */
338 #define list_entry(ptr, type, member) 339 container_of(ptr, type, member)
340
341 /**
342 * list_first_entry - get the first element from a list
343 * @ptr: the list head to take the element from.
344 * @type: the type of the struct this is embedded in.
345 * @member: the name of the list_struct within the struct.
346 *
347 * Note, that list is expected to be not empty.
348 */
349 #define list_first_entry(ptr, type, member) 350 list_entry((ptr)->next, type, member)
351
352 /**
353 * list_for_each - iterate over a list
354 * @pos: the &struct list_head to use as a loop cursor.
355 * @head: the head for your list.
356 */
357 #define list_for_each(pos, head) 358 for (pos = (head)->next; pos != (head); pos = pos->next)
359
360 /**
361 * __list_for_each - iterate over a list
362 * @pos: the &struct list_head to use as a loop cursor.
363 * @head: the head for your list.
364 *
365 * This variant doesn‘t differ from list_for_each() any more.
366 * We don‘t do prefetching in either case.
367 */
368 #define __list_for_each(pos, head) 369 for (pos = (head)->next; pos != (head); pos = pos->next)
370
371 /**
372 * list_for_each_prev - iterate over a list backwards
373 * @pos: the &struct list_head to use as a loop cursor.
374 * @head: the head for your list.
375 */
376 #define list_for_each_prev(pos, head) 377 for (pos = (head)->prev; pos != (head); pos = pos->prev)
378
379 /**
380 * list_for_each_safe - iterate over a list safe against removal of list entry
381 * @pos: the &struct list_head to use as a loop cursor.
382 * @n: another &struct list_head to use as temporary storage
383 * @head: the head for your list.
384 */
385 #define list_for_each_safe(pos, n, head) 386 for (pos = (head)->next, n = pos->next; pos != (head); 387 pos = n, n = pos->next)
388
389 /**
390 * list_for_each_prev_safe - iterate over a list backwards safe against removal of list entry
391 * @pos: the &struct list_head to use as a loop cursor.
392 * @n: another &struct list_head to use as temporary storage
393 * @head: the head for your list.
394 */
395 #define list_for_each_prev_safe(pos, n, head) 396 for (pos = (head)->prev, n = pos->prev; 397 pos != (head); 398 pos = n, n = pos->prev)
399
400 /**
401 * list_for_each_entry - iterate over list of given type
402 * @pos: the type * to use as a loop cursor.
403 * @head: the head for your list.
404 * @member: the name of the list_struct within the struct.
405 */
406 #define list_for_each_entry(pos, head, member) 407 for (pos = list_entry((head)->next, typeof(*pos), member); 408 &pos->member != (head); 409 pos = list_entry(pos->member.next, typeof(*pos), member))
410
411 /**
412 * list_for_each_entry_reverse - iterate backwards over list of given type.
413 * @pos: the type * to use as a loop cursor.
414 * @head: the head for your list.
415 * @member: the name of the list_struct within the struct.
416 */
417 #define list_for_each_entry_reverse(pos, head, member) 418 for (pos = list_entry((head)->prev, typeof(*pos), member); 419 &pos->member != (head); 420 pos = list_entry(pos->member.prev, typeof(*pos), member))
421
422 /**
423 * list_prepare_entry - prepare a pos entry for use in list_for_each_entry_continue()
424 * @pos: the type * to use as a start point
425 * @head: the head of the list
426 * @member: the name of the list_struct within the struct.
427 *
428 * Prepares a pos entry for use as a start point in list_for_each_entry_continue().
429 */
430 #define list_prepare_entry(pos, head, member) 431 ((pos) ? : list_entry(head, typeof(*pos), member))
432
433 /**
434 * list_for_each_entry_continue - continue iteration over list of given type
435 * @pos: the type * to use as a loop cursor.
436 * @head: the head for your list.
437 * @member: the name of the list_struct within the struct.
438 *
439 * Continue to iterate over list of given type, continuing after
440 * the current position.
441 */
442 #define list_for_each_entry_continue(pos, head, member) 443 for (pos = list_entry(pos->member.next, typeof(*pos), member); 444 &pos->member != (head); 445 pos = list_entry(pos->member.next, typeof(*pos), member))
446
447 /**
448 * list_for_each_entry_continue_reverse - iterate backwards from the given point
449 * @pos: the type * to use as a loop cursor.
450 * @head: the head for your list.
451 * @member: the name of the list_struct within the struct.
452 *
453 * Start to iterate over list of given type backwards, continuing after
454 * the current position.
455 */
456 #define list_for_each_entry_continue_reverse(pos, head, member) 457 for (pos = list_entry(pos->member.prev, typeof(*pos), member); 458 &pos->member != (head); 459 pos = list_entry(pos->member.prev, typeof(*pos), member))
460
461 /**
462 * list_for_each_entry_from - iterate over list of given type from the current point
463 * @pos: the type * to use as a loop cursor.
464 * @head: the head for your list.
465 * @member: the name of the list_struct within the struct.
466 *
467 * Iterate over list of given type, continuing from current position.
468 */
469 #define list_for_each_entry_from(pos, head, member) 470 for (; &pos->member != (head); 471 pos = list_entry(pos->member.next, typeof(*pos), member))
472
473 /**
474 * list_for_each_entry_safe - iterate over list of given type safe against removal of list entry
475 * @pos: the type * to use as a loop cursor.
476 * @n: another type * to use as temporary storage
477 * @head: the head for your list.
478 * @member: the name of the list_struct within the struct.
479 */
480 #define list_for_each_entry_safe(pos, n, head, member) 481 for (pos = list_entry((head)->next, typeof(*pos), member), 482 n = list_entry(pos->member.next, typeof(*pos), member); 483 &pos->member != (head); 484 pos = n, n = list_entry(n->member.next, typeof(*n), member))
485
486 /**
487 * list_for_each_entry_safe_continue - continue list iteration safe against removal
488 * @pos: the type * to use as a loop cursor.
489 * @n: another type * to use as temporary storage
490 * @head: the head for your list.
491 * @member: the name of the list_struct within the struct.
492 *
493 * Iterate over list of given type, continuing after current point,
494 * safe against removal of list entry.
495 */
496 #define list_for_each_entry_safe_continue(pos, n, head, member) 497 for (pos = list_entry(pos->member.next, typeof(*pos), member), 498 n = list_entry(pos->member.next, typeof(*pos), member); 499 &pos->member != (head); 500 pos = n, n = list_entry(n->member.next, typeof(*n), member))
501
502 /**
503 * list_for_each_entry_safe_from - iterate over list from current point safe against removal
504 * @pos: the type * to use as a loop cursor.
505 * @n: another type * to use as temporary storage
506 * @head: the head for your list.
507 * @member: the name of the list_struct within the struct.
508 *
509 * Iterate over list of given type from current point, safe against
510 * removal of list entry.
511 */
512 #define list_for_each_entry_safe_from(pos, n, head, member) 513 for (n = list_entry(pos->member.next, typeof(*pos), member); 514 &pos->member != (head); 515 pos = n, n = list_entry(n->member.next, typeof(*n), member))
516
517 /**
518 * list_for_each_entry_safe_reverse - iterate backwards over list safe against removal
519 * @pos: the type * to use as a loop cursor.
520 * @n: another type * to use as temporary storage
521 * @head: the head for your list.
522 * @member: the name of the list_struct within the struct.
523 *
524 * Iterate backwards over list of given type, safe against removal
525 * of list entry.
526 */
527 #define list_for_each_entry_safe_reverse(pos, n, head, member) 528 for (pos = list_entry((head)->prev, typeof(*pos), member), 529 n = list_entry(pos->member.prev, typeof(*pos), member); 530 &pos->member != (head); 531 pos = n, n = list_entry(n->member.prev, typeof(*n), member))
532
533 /**
534 * list_safe_reset_next - reset a stale list_for_each_entry_safe loop
535 * @pos: the loop cursor used in the list_for_each_entry_safe loop
536 * @n: temporary storage used in list_for_each_entry_safe
537 * @member: the name of the list_struct within the struct.
538 *
539 * list_safe_reset_next is not safe to use in general if the list may be
540 * modified concurrently (eg. the lock is dropped in the loop body). An
541 * exception to this is if the cursor element (pos) is pinned in the list,
542 * and list_safe_reset_next is called after re-taking the lock and before
543 * completing the current iteration of the loop body.
544 */
545 #define list_safe_reset_next(pos, n, member) 546 n = list_entry(pos->member.next, typeof(*pos), member)
547
548 /*
549 * Double linked lists with a single pointer list head.
550 * Mostly useful for hash tables where the two pointer list head is
551 * too wasteful.
552 * You lose the ability to access the tail in O(1).
553 */
554
555 #endif
list.h
测试用例：
1 #include "list.h"
2 #include <stdio.h>
3 #include <stdlib.h>
4
5
6 #define SZ 32
7
8 #define CNT 66
9
10 struct ourstu {
11 char name[SZ];
12 int num;
13 struct list_head list;
14 };
15 #define offsetof(TYPE, MEMBER) ((size_t) &((TYPE *)0)->MEMBER)
16
17 #define container_of(ptr, type, member) ({ 18 const typeof( ((type *)0)->member ) *__mptr = (ptr); 19 (type *)( (char *)__mptr - offsetof(type,member) );})
20
21
22
23 /*创建双向循环链表*/
24 LIST_HEAD(head);
25
26 static int demo_init(void)
27 {
28 int i;
29 struct ourstu *stu;
30
31 struct list_head *pos, *n;
32
33 for (i = 0; i < CNT; i++) {
34 stu = malloc(sizeof(struct ourstu));
35 if (NULL == stu) {
36 goto error0;
37 }
38 stu->num = 9527 + i;
39 sprintf(stu->name, "spring%d", i);
40
41 list_add_tail(&stu->list, &head);
42 }
43
44 list_for_each (pos, &head) {
45 stu = container_of(pos, struct ourstu, list);
46 printf("%s‘s number %d\n", stu->name, stu->num);
47 }
48
49
50 return 0;
51
52 error0:
53 list_for_each_safe(pos, n, &head) {
54 stu = container_of(pos, struct ourstu, list);
55 printf("%s see bye...\n", stu->name);
56 free(stu);
57 }
58
59 return -1;
60 }
61
62
63
64 static void demo_exit(void)
65 {
66 struct list_head *n, *pos;
67 struct ourstu *stu;
68
69 list_for_each_safe(pos, n, &head) {
70 stu = container_of(pos, struct ourstu, list);
71 printf("%s say bye...\n", stu->name);
72 free(stu);
73 }
74
75 printf("see you, kernel...\n");
76 }
77
78 int main()
79 {
80 demo_init();
81 demo_exit();
82 }
先学习到这，以后用到 list.h 中更多的再来补充。
原文地址：https://www.cnblogs.com/jason-linux/p/10465827.html
时间： 2024-11-06 11:25:48