Dentry cache pruning function
[akaros.git] / kern / include / sys / queue.h
1 /*-
2  * Copyright (c) 1991, 1993
3  *      The Regents of the University of California.  All rights reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions
7  * are met:
8  * 1. Redistributions of source code must retain the above copyright
9  *    notice, this list of conditions and the following disclaimer.
10  * 2. Redistributions in binary form must reproduce the above copyright
11  *    notice, this list of conditions and the following disclaimer in the
12  *    documentation and/or other materials provided with the distribution.
13  * 4. Neither the name of the University nor the names of its contributors
14  *    may be used to endorse or promote products derived from this software
15  *    without specific prior written permission.
16  *
17  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27  * SUCH DAMAGE.
28  *
29  *      @(#)queue.h     8.5 (Berkeley) 8/20/94
30  * $FreeBSD$
31  */
32
33 #ifndef ROS_KERN_SYS_QUEUE_H
34 #define ROS_KERN_SYS_QUEUE_H
35
36 #include <ros/common.h>    /* for __offsetof */
37
38 /*
39  * This file defines four types of data structures: singly-linked lists,
40  * singly-linked tail queues, lists and tail queues.
41  *
42  * A singly-linked list is headed by a single forward pointer. The elements
43  * are singly linked for minimum space and pointer manipulation overhead at
44  * the expense of O(n) removal for arbitrary elements. New elements can be
45  * added to the list after an existing element or at the head of the list.
46  * Elements being removed from the head of the list should use the explicit
47  * macro for this purpose for optimum efficiency. A singly-linked list may
48  * only be traversed in the forward direction.  Singly-linked lists are ideal
49  * for applications with large datasets and few or no removals or for
50  * implementing a LIFO queue.
51  *
52  * A singly-linked tail queue is headed by a pair of pointers, one to the
53  * head of the list and the other to the tail of the list. The elements are
54  * singly linked for minimum space and pointer manipulation overhead at the
55  * expense of O(n) removal for arbitrary elements. New elements can be added
56  * to the list after an existing element, at the head of the list, or at the
57  * end of the list. Elements being removed from the head of the tail queue
58  * should use the explicit macro for this purpose for optimum efficiency.
59  * A singly-linked tail queue may only be traversed in the forward direction.
60  * Singly-linked tail queues are ideal for applications with large datasets
61  * and few or no removals or for implementing a FIFO queue.
62  *
63  * A list is headed by a single forward pointer (or an array of forward
64  * pointers for a hash table header). The elements are doubly linked
65  * so that an arbitrary element can be removed without a need to
66  * traverse the list. New elements can be added to the list before
67  * or after an existing element or at the head of the list. A list
68  * may only be traversed in the forward direction.
69  *
70  * A tail queue is headed by a pair of pointers, one to the head of the
71  * list and the other to the tail of the list. The elements are doubly
72  * linked so that an arbitrary element can be removed without a need to
73  * traverse the list. New elements can be added to the list before or
74  * after an existing element, at the head of the list, or at the end of
75  * the list. A tail queue may be traversed in either direction.
76  *
77  * For details on the use of these macros, see the queue(3) manual page.
78  *
79  *
80  *                              SLIST   LIST    STAILQ  TAILQ
81  * _HEAD                        +       +       +       +
82  * _HEAD_INITIALIZER            +       +       +       +
83  * _ENTRY                       +       +       +       +
84  * _INIT                        +       +       +       +
85  * _EMPTY                       +       +       +       +
86  * _FIRST                       +       +       +       +
87  * _NEXT                        +       +       +       +
88  * _PREV                        -       -       -       +
89  * _LAST                        -       -       +       +
90  * _FOREACH                     +       +       +       +
91  * _FOREACH_SAFE                +       +       +       +
92  * _FOREACH_REVERSE             -       -       -       +
93  * _FOREACH_REVERSE_SAFE        -       -       -       +
94  * _INSERT_HEAD                 +       +       +       +
95  * _INSERT_BEFORE               -       +       -       +
96  * _INSERT_AFTER                +       +       +       +
97  * _INSERT_TAIL                 -       -       +       +
98  * _CONCAT                      -       -       +       +
99  * _REMOVE_AFTER                +       -       +       -
100  * _REMOVE_HEAD                 +       -       +       -
101  * _REMOVE                      +       +       +       +
102  *
103  */
104 #ifdef QUEUE_MACRO_DEBUG
105 /* Store the last 2 places the queue element or head was altered */
106 struct qm_trace {
107         char * lastfile;
108         int lastline;
109         char * prevfile;
110         int prevline;
111 };
112
113 #define TRACEBUF        struct qm_trace trace;
114 #define TRASHIT(x)      do {(x) = (void *)-1;} while (0)
115 #define QMD_SAVELINK(name, link)        void **name = (void *)&(link)
116
117 #define QMD_TRACE_HEAD(head) do {                                       \
118         (head)->trace.prevline = (head)->trace.lastline;                \
119         (head)->trace.prevfile = (head)->trace.lastfile;                \
120         (head)->trace.lastline = __LINE__;                              \
121         (head)->trace.lastfile = __FILE__;                              \
122 } while (0)
123
124 #define QMD_TRACE_ELEM(elem) do {                                       \
125         (elem)->trace.prevline = (elem)->trace.lastline;                \
126         (elem)->trace.prevfile = (elem)->trace.lastfile;                \
127         (elem)->trace.lastline = __LINE__;                              \
128         (elem)->trace.lastfile = __FILE__;                              \
129 } while (0)
130
131 #else
132 #define QMD_TRACE_ELEM(elem)
133 #define QMD_TRACE_HEAD(head)
134 #define QMD_SAVELINK(name, link)
135 #define TRACEBUF
136 #define TRASHIT(x)
137 #endif  /* QUEUE_MACRO_DEBUG */
138
139 /*
140  * Singly-linked List declarations.
141  */
142 #define SLIST_HEAD(name, type)                                          \
143 struct name {                                                           \
144         struct type *slh_first; /* first element */                     \
145 }
146
147 #define SLIST_HEAD_INITIALIZER(head)                                    \
148         { NULL }
149
150 #define SLIST_ENTRY(type)                                               \
151 struct {                                                                \
152         struct type *sle_next;  /* next element */                      \
153 }
154
155 /*
156  * Singly-linked List functions.
157  */
158 #define SLIST_EMPTY(head)       ((head)->slh_first == NULL)
159
160 #define SLIST_FIRST(head)       ((head)->slh_first)
161
162 #define SLIST_FOREACH(var, head, field)                                 \
163         for ((var) = SLIST_FIRST((head));                               \
164             (var);                                                      \
165             (var) = SLIST_NEXT((var), field))
166
167 #define SLIST_FOREACH_SAFE(var, head, field, tvar)                      \
168         for ((var) = SLIST_FIRST((head));                               \
169             (var) && ((tvar) = SLIST_NEXT((var), field), 1);            \
170             (var) = (tvar))
171
172 #define SLIST_FOREACH_PREVPTR(var, varp, head, field)                   \
173         for ((varp) = &SLIST_FIRST((head));                             \
174             ((var) = *(varp)) != NULL;                                  \
175             (varp) = &SLIST_NEXT((var), field))
176
177 #define SLIST_INIT(head) do {                                           \
178         SLIST_FIRST((head)) = NULL;                                     \
179 } while (0)
180
181 #define SLIST_INSERT_AFTER(slistelm, elm, field) do {                   \
182         SLIST_NEXT((elm), field) = SLIST_NEXT((slistelm), field);       \
183         SLIST_NEXT((slistelm), field) = (elm);                          \
184 } while (0)
185
186 #define SLIST_INSERT_HEAD(head, elm, field) do {                        \
187         SLIST_NEXT((elm), field) = SLIST_FIRST((head));                 \
188         SLIST_FIRST((head)) = (elm);                                    \
189 } while (0)
190
191 #define SLIST_NEXT(elm, field)  ((elm)->field.sle_next)
192
193 #define SLIST_REMOVE(head, elm, type, field) do {                       \
194         QMD_SAVELINK(oldnext, (elm)->field.sle_next);                   \
195         if (SLIST_FIRST((head)) == (elm)) {                             \
196                 SLIST_REMOVE_HEAD((head), field);                       \
197         }                                                               \
198         else {                                                          \
199                 struct type *curelm = SLIST_FIRST((head));              \
200                 while (SLIST_NEXT(curelm, field) != (elm))              \
201                         curelm = SLIST_NEXT(curelm, field);             \
202                 SLIST_REMOVE_AFTER(curelm, field);                      \
203         }                                                               \
204         TRASHIT(*oldnext);                                              \
205 } while (0)
206
207 #define SLIST_REMOVE_AFTER(elm, field) do {                             \
208         SLIST_NEXT(elm, field) =                                        \
209             SLIST_NEXT(SLIST_NEXT(elm, field), field);                  \
210 } while (0)
211
212 #define SLIST_REMOVE_HEAD(head, field) do {                             \
213         SLIST_FIRST((head)) = SLIST_NEXT(SLIST_FIRST((head)), field);   \
214 } while (0)
215
216 /*
217  * Singly-linked Tail queue declarations.
218  */
219 #define STAILQ_HEAD(name, type)                                         \
220 struct name {                                                           \
221         struct type *stqh_first;/* first element */                     \
222         struct type **stqh_last;/* addr of last next element */         \
223 }
224
225 #define STAILQ_HEAD_INITIALIZER(head)                                   \
226         { NULL, &(head).stqh_first }
227
228 #define STAILQ_ENTRY(type)                                              \
229 struct {                                                                \
230         struct type *stqe_next; /* next element */                      \
231 }
232
233 /*
234  * Singly-linked Tail queue functions.
235  */
236 #define STAILQ_CONCAT(head1, head2) do {                                \
237         if (!STAILQ_EMPTY((head2))) {                                   \
238                 *(head1)->stqh_last = (head2)->stqh_first;              \
239                 (head1)->stqh_last = (head2)->stqh_last;                \
240                 STAILQ_INIT((head2));                                   \
241         }                                                               \
242 } while (0)
243
244 #define STAILQ_EMPTY(head)      ((head)->stqh_first == NULL)
245
246 #define STAILQ_FIRST(head)      ((head)->stqh_first)
247
248 #define STAILQ_FOREACH(var, head, field)                                \
249         for((var) = STAILQ_FIRST((head));                               \
250            (var);                                                       \
251            (var) = STAILQ_NEXT((var), field))
252
253
254 #define STAILQ_FOREACH_SAFE(var, head, field, tvar)                     \
255         for ((var) = STAILQ_FIRST((head));                              \
256             (var) && ((tvar) = STAILQ_NEXT((var), field), 1);           \
257             (var) = (tvar))
258
259 #define STAILQ_INIT(head) do {                                          \
260         STAILQ_FIRST((head)) = NULL;                                    \
261         (head)->stqh_last = &STAILQ_FIRST((head));                      \
262 } while (0)
263
264 #define STAILQ_INSERT_AFTER(head, tqelm, elm, field) do {               \
265         if ((STAILQ_NEXT((elm), field) = STAILQ_NEXT((tqelm), field)) == NULL)\
266                 (head)->stqh_last = &STAILQ_NEXT((elm), field);         \
267         STAILQ_NEXT((tqelm), field) = (elm);                            \
268 } while (0)
269
270 #define STAILQ_INSERT_HEAD(head, elm, field) do {                       \
271         if ((STAILQ_NEXT((elm), field) = STAILQ_FIRST((head))) == NULL) \
272                 (head)->stqh_last = &STAILQ_NEXT((elm), field);         \
273         STAILQ_FIRST((head)) = (elm);                                   \
274 } while (0)
275
276 #define STAILQ_INSERT_TAIL(head, elm, field) do {                       \
277         STAILQ_NEXT((elm), field) = NULL;                               \
278         *(head)->stqh_last = (elm);                                     \
279         (head)->stqh_last = &STAILQ_NEXT((elm), field);                 \
280 } while (0)
281
282 #define STAILQ_LAST(head, type, field)                                  \
283         (STAILQ_EMPTY((head)) ?                                         \
284                 NULL :                                                  \
285                 ((struct type *)(void *)                                \
286                 ((char *)((head)->stqh_last) - __offsetof(struct type, field))))
287
288 #define STAILQ_NEXT(elm, field) ((elm)->field.stqe_next)
289
290 #define STAILQ_REMOVE(head, elm, type, field) do {                      \
291         QMD_SAVELINK(oldnext, (elm)->field.stqe_next);                  \
292         if (STAILQ_FIRST((head)) == (elm)) {                            \
293                 STAILQ_REMOVE_HEAD((head), field);                      \
294         }                                                               \
295         else {                                                          \
296                 struct type *curelm = STAILQ_FIRST((head));             \
297                 while (STAILQ_NEXT(curelm, field) != (elm))             \
298                         curelm = STAILQ_NEXT(curelm, field);            \
299                 STAILQ_REMOVE_AFTER(head, curelm, field);               \
300         }                                                               \
301         TRASHIT(*oldnext);                                              \
302 } while (0)
303
304 #define STAILQ_REMOVE_HEAD(head, field) do {                            \
305         if ((STAILQ_FIRST((head)) =                                     \
306              STAILQ_NEXT(STAILQ_FIRST((head)), field)) == NULL)         \
307                 (head)->stqh_last = &STAILQ_FIRST((head));              \
308 } while (0)
309
310 #define STAILQ_REMOVE_AFTER(head, elm, field) do {                      \
311         if ((STAILQ_NEXT(elm, field) =                                  \
312              STAILQ_NEXT(STAILQ_NEXT(elm, field), field)) == NULL)      \
313                 (head)->stqh_last = &STAILQ_NEXT((elm), field);         \
314 } while (0)
315
316 #define STAILQ_SWAP(head1, head2, type) do {                            \
317         struct type *swap_first = STAILQ_FIRST(head1);                  \
318         struct type **swap_last = (head1)->stqh_last;                   \
319         STAILQ_FIRST(head1) = STAILQ_FIRST(head2);                      \
320         (head1)->stqh_last = (head2)->stqh_last;                        \
321         STAILQ_FIRST(head2) = swap_first;                               \
322         (head2)->stqh_last = swap_last;                                 \
323         if (STAILQ_EMPTY(head1))                                        \
324                 (head1)->stqh_last = &STAILQ_FIRST(head1);              \
325         if (STAILQ_EMPTY(head2))                                        \
326                 (head2)->stqh_last = &STAILQ_FIRST(head2);              \
327 } while (0)
328
329
330 /*
331  * List declarations.
332  */
333 #define LIST_HEAD(name, type)                                           \
334 struct name {                                                           \
335         struct type *lh_first;  /* first element */                     \
336 }
337
338 #define LIST_HEAD_INITIALIZER(head)                                     \
339         { NULL }
340
341 #define LIST_ENTRY(type)                                                \
342 struct {                                                                \
343         struct type *le_next;   /* next element */                      \
344         struct type **le_prev;  /* address of previous next element */  \
345 }
346
347 /*
348  * List functions.
349  */
350
351 #if (defined(_KERNEL) && defined(INVARIANTS))
352 #define QMD_LIST_CHECK_HEAD(head, field) do {                           \
353         if (LIST_FIRST((head)) != NULL &&                               \
354             LIST_FIRST((head))->field.le_prev !=                        \
355              &LIST_FIRST((head)))                                       \
356                 panic("Bad list head %p first->prev != head", (head));  \
357 } while (0)
358
359 #define QMD_LIST_CHECK_NEXT(elm, field) do {                            \
360         if (LIST_NEXT((elm), field) != NULL &&                          \
361             LIST_NEXT((elm), field)->field.le_prev !=                   \
362              &((elm)->field.le_next))                                   \
363                 panic("Bad link elm %p next->prev != elm", (elm));      \
364 } while (0)
365
366 #define QMD_LIST_CHECK_PREV(elm, field) do {                            \
367         if (*(elm)->field.le_prev != (elm))                             \
368                 panic("Bad link elm %p prev->next != elm", (elm));      \
369 } while (0)
370 #else
371 #define QMD_LIST_CHECK_HEAD(head, field)
372 #define QMD_LIST_CHECK_NEXT(elm, field)
373 #define QMD_LIST_CHECK_PREV(elm, field)
374 #endif /* (_KERNEL && INVARIANTS) */
375
376 #define LIST_EMPTY(head)        ((head)->lh_first == NULL)
377
378 #define LIST_FIRST(head)        ((head)->lh_first)
379
380 #define LIST_FOREACH(var, head, field)                                  \
381         for ((var) = LIST_FIRST((head));                                \
382             (var);                                                      \
383             (var) = LIST_NEXT((var), field))
384
385 #define LIST_FOREACH_SAFE(var, head, field, tvar)                       \
386         for ((var) = LIST_FIRST((head));                                \
387             (var) && ((tvar) = LIST_NEXT((var), field), 1);             \
388             (var) = (tvar))
389
390 #define LIST_INIT(head) do {                                            \
391         LIST_FIRST((head)) = NULL;                                      \
392 } while (0)
393
394 #define LIST_INSERT_AFTER(listelm, elm, field) do {                     \
395         QMD_LIST_CHECK_NEXT(listelm, field);                            \
396         if ((LIST_NEXT((elm), field) = LIST_NEXT((listelm), field)) != NULL)\
397                 LIST_NEXT((listelm), field)->field.le_prev =            \
398                     &LIST_NEXT((elm), field);                           \
399         LIST_NEXT((listelm), field) = (elm);                            \
400         (elm)->field.le_prev = &LIST_NEXT((listelm), field);            \
401 } while (0)
402
403 #define LIST_INSERT_BEFORE(listelm, elm, field) do {                    \
404         QMD_LIST_CHECK_PREV(listelm, field);                            \
405         (elm)->field.le_prev = (listelm)->field.le_prev;                \
406         LIST_NEXT((elm), field) = (listelm);                            \
407         *(listelm)->field.le_prev = (elm);                              \
408         (listelm)->field.le_prev = &LIST_NEXT((elm), field);            \
409 } while (0)
410
411 #define LIST_INSERT_HEAD(head, elm, field) do {                         \
412         QMD_LIST_CHECK_HEAD((head), field);                             \
413         if ((LIST_NEXT((elm), field) = LIST_FIRST((head))) != NULL)     \
414                 LIST_FIRST((head))->field.le_prev = &LIST_NEXT((elm), field);\
415         LIST_FIRST((head)) = (elm);                                     \
416         (elm)->field.le_prev = &LIST_FIRST((head));                     \
417 } while (0)
418
419 #define LIST_NEXT(elm, field)   ((elm)->field.le_next)
420
421 #define LIST_REMOVE(elm, field) do {                                    \
422         QMD_SAVELINK(oldnext, (elm)->field.le_next);                    \
423         QMD_SAVELINK(oldprev, (elm)->field.le_prev);                    \
424         QMD_LIST_CHECK_NEXT(elm, field);                                \
425         QMD_LIST_CHECK_PREV(elm, field);                                \
426         if (LIST_NEXT((elm), field) != NULL)                            \
427                 LIST_NEXT((elm), field)->field.le_prev =                \
428                     (elm)->field.le_prev;                               \
429         *(elm)->field.le_prev = LIST_NEXT((elm), field);                \
430         TRASHIT(*oldnext);                                              \
431         TRASHIT(*oldprev);                                              \
432 } while (0)
433
434 #define LIST_SWAP(head1, head2, type, field) do {                       \
435         struct type *swap_tmp = LIST_FIRST((head1));                    \
436         LIST_FIRST((head1)) = LIST_FIRST((head2));                      \
437         LIST_FIRST((head2)) = swap_tmp;                                 \
438         if ((swap_tmp = LIST_FIRST((head1))) != NULL)                   \
439                 swap_tmp->field.le_prev = &LIST_FIRST((head1));         \
440         if ((swap_tmp = LIST_FIRST((head2))) != NULL)                   \
441                 swap_tmp->field.le_prev = &LIST_FIRST((head2));         \
442 } while (0)
443
444 /*
445  * Tail queue declarations.
446  */
447 #define TAILQ_HEAD(name, type)                                          \
448 struct name {                                                           \
449         struct type *tqh_first; /* first element */                     \
450         struct type **tqh_last; /* addr of last next element */         \
451         TRACEBUF                                                        \
452 }
453
454 #define TAILQ_HEAD_INITIALIZER(head)                                    \
455         { NULL, &(head).tqh_first }
456
457 #define TAILQ_ENTRY(type)                                               \
458 struct {                                                                \
459         struct type *tqe_next;  /* next element */                      \
460         struct type **tqe_prev; /* address of previous next element */  \
461         TRACEBUF                                                        \
462 }
463
464 /*
465  * Tail queue functions.
466  */
467 #if (defined(_KERNEL) && defined(INVARIANTS))
468 #define QMD_TAILQ_CHECK_HEAD(head, field) do {                          \
469         if (!TAILQ_EMPTY(head) &&                                       \
470             TAILQ_FIRST((head))->field.tqe_prev !=                      \
471              &TAILQ_FIRST((head)))                                      \
472                 panic("Bad tailq head %p first->prev != head", (head)); \
473 } while (0)
474
475 #define QMD_TAILQ_CHECK_TAIL(head, field) do {                          \
476         if (*(head)->tqh_last != NULL)                                  \
477                 panic("Bad tailq NEXT(%p->tqh_last) != NULL", (head));  \
478 } while (0)
479
480 #define QMD_TAILQ_CHECK_NEXT(elm, field) do {                           \
481         if (TAILQ_NEXT((elm), field) != NULL &&                         \
482             TAILQ_NEXT((elm), field)->field.tqe_prev !=                 \
483              &((elm)->field.tqe_next))                                  \
484                 panic("Bad link elm %p next->prev != elm", (elm));      \
485 } while (0)
486
487 #define QMD_TAILQ_CHECK_PREV(elm, field) do {                           \
488         if (*(elm)->field.tqe_prev != (elm))                            \
489                 panic("Bad link elm %p prev->next != elm", (elm));      \
490 } while (0)
491 #else
492 #define QMD_TAILQ_CHECK_HEAD(head, field)
493 #define QMD_TAILQ_CHECK_TAIL(head, headname)
494 #define QMD_TAILQ_CHECK_NEXT(elm, field)
495 #define QMD_TAILQ_CHECK_PREV(elm, field)
496 #endif /* (_KERNEL && INVARIANTS) */
497
498 #define TAILQ_CONCAT(head1, head2, field) do {                          \
499         if (!TAILQ_EMPTY(head2)) {                                      \
500                 *(head1)->tqh_last = (head2)->tqh_first;                \
501                 (head2)->tqh_first->field.tqe_prev = (head1)->tqh_last; \
502                 (head1)->tqh_last = (head2)->tqh_last;                  \
503                 TAILQ_INIT((head2));                                    \
504                 QMD_TRACE_HEAD(head1);                                  \
505                 QMD_TRACE_HEAD(head2);                                  \
506         }                                                               \
507 } while (0)
508
509 #define TAILQ_EMPTY(head)       ((head)->tqh_first == NULL)
510
511 #define TAILQ_FIRST(head)       ((head)->tqh_first)
512
513 #define TAILQ_FOREACH(var, head, field)                                 \
514         for ((var) = TAILQ_FIRST((head));                               \
515             (var);                                                      \
516             (var) = TAILQ_NEXT((var), field))
517
518 #define TAILQ_FOREACH_SAFE(var, head, field, tvar)                      \
519         for ((var) = TAILQ_FIRST((head));                               \
520             (var) && ((tvar) = TAILQ_NEXT((var), field), 1);            \
521             (var) = (tvar))
522
523 #define TAILQ_FOREACH_REVERSE(var, head, headname, field)               \
524         for ((var) = TAILQ_LAST((head), headname);                      \
525             (var);                                                      \
526             (var) = TAILQ_PREV((var), headname, field))
527
528 #define TAILQ_FOREACH_REVERSE_SAFE(var, head, headname, field, tvar)    \
529         for ((var) = TAILQ_LAST((head), headname);                      \
530             (var) && ((tvar) = TAILQ_PREV((var), headname, field), 1);  \
531             (var) = (tvar))
532
533 #define TAILQ_INIT(head) do {                                           \
534         TAILQ_FIRST((head)) = NULL;                                     \
535         (head)->tqh_last = &TAILQ_FIRST((head));                        \
536         QMD_TRACE_HEAD(head);                                           \
537 } while (0)
538
539 #define TAILQ_INSERT_AFTER(head, listelm, elm, field) do {              \
540         QMD_TAILQ_CHECK_NEXT(listelm, field);                           \
541         if ((TAILQ_NEXT((elm), field) = TAILQ_NEXT((listelm), field)) != NULL)\
542                 TAILQ_NEXT((elm), field)->field.tqe_prev =              \
543                     &TAILQ_NEXT((elm), field);                          \
544         else {                                                          \
545                 (head)->tqh_last = &TAILQ_NEXT((elm), field);           \
546                 QMD_TRACE_HEAD(head);                                   \
547         }                                                               \
548         TAILQ_NEXT((listelm), field) = (elm);                           \
549         (elm)->field.tqe_prev = &TAILQ_NEXT((listelm), field);          \
550         QMD_TRACE_ELEM(&(elm)->field);                                  \
551         QMD_TRACE_ELEM(&listelm->field);                                \
552 } while (0)
553
554 #define TAILQ_INSERT_BEFORE(listelm, elm, field) do {                   \
555         QMD_TAILQ_CHECK_PREV(listelm, field);                           \
556         (elm)->field.tqe_prev = (listelm)->field.tqe_prev;              \
557         TAILQ_NEXT((elm), field) = (listelm);                           \
558         *(listelm)->field.tqe_prev = (elm);                             \
559         (listelm)->field.tqe_prev = &TAILQ_NEXT((elm), field);          \
560         QMD_TRACE_ELEM(&(elm)->field);                                  \
561         QMD_TRACE_ELEM(&listelm->field);                                \
562 } while (0)
563
564 #define TAILQ_INSERT_HEAD(head, elm, field) do {                        \
565         QMD_TAILQ_CHECK_HEAD(head, field);                              \
566         if ((TAILQ_NEXT((elm), field) = TAILQ_FIRST((head))) != NULL)   \
567                 TAILQ_FIRST((head))->field.tqe_prev =                   \
568                     &TAILQ_NEXT((elm), field);                          \
569         else                                                            \
570                 (head)->tqh_last = &TAILQ_NEXT((elm), field);           \
571         TAILQ_FIRST((head)) = (elm);                                    \
572         (elm)->field.tqe_prev = &TAILQ_FIRST((head));                   \
573         QMD_TRACE_HEAD(head);                                           \
574         QMD_TRACE_ELEM(&(elm)->field);                                  \
575 } while (0)
576
577 #define TAILQ_INSERT_TAIL(head, elm, field) do {                        \
578         QMD_TAILQ_CHECK_TAIL(head, field);                              \
579         TAILQ_NEXT((elm), field) = NULL;                                \
580         (elm)->field.tqe_prev = (head)->tqh_last;                       \
581         *(head)->tqh_last = (elm);                                      \
582         (head)->tqh_last = &TAILQ_NEXT((elm), field);                   \
583         QMD_TRACE_HEAD(head);                                           \
584         QMD_TRACE_ELEM(&(elm)->field);                                  \
585 } while (0)
586
587 #define TAILQ_LAST(head, headname)                                      \
588         (*(((struct headname *)((head)->tqh_last))->tqh_last))
589
590 #define TAILQ_NEXT(elm, field) ((elm)->field.tqe_next)
591
592 #define TAILQ_PREV(elm, headname, field)                                \
593         (*(((struct headname *)((elm)->field.tqe_prev))->tqh_last))
594
595 #define TAILQ_REMOVE(head, elm, field) do {                             \
596         QMD_SAVELINK(oldnext, (elm)->field.tqe_next);                   \
597         QMD_SAVELINK(oldprev, (elm)->field.tqe_prev);                   \
598         QMD_TAILQ_CHECK_NEXT(elm, field);                               \
599         QMD_TAILQ_CHECK_PREV(elm, field);                               \
600         if ((TAILQ_NEXT((elm), field)) != NULL)                         \
601                 TAILQ_NEXT((elm), field)->field.tqe_prev =              \
602                     (elm)->field.tqe_prev;                              \
603         else {                                                          \
604                 (head)->tqh_last = (elm)->field.tqe_prev;               \
605                 QMD_TRACE_HEAD(head);                                   \
606         }                                                               \
607         *(elm)->field.tqe_prev = TAILQ_NEXT((elm), field);              \
608         TRASHIT(*oldnext);                                              \
609         TRASHIT(*oldprev);                                              \
610         QMD_TRACE_ELEM(&(elm)->field);                                  \
611 } while (0)
612
613 #define TAILQ_SWAP(head1, head2, type, field) do {                      \
614         struct type *swap_first = (head1)->tqh_first;                   \
615         struct type **swap_last = (head1)->tqh_last;                    \
616         (head1)->tqh_first = (head2)->tqh_first;                        \
617         (head1)->tqh_last = (head2)->tqh_last;                          \
618         (head2)->tqh_first = swap_first;                                \
619         (head2)->tqh_last = swap_last;                                  \
620         if ((swap_first = (head1)->tqh_first) != NULL)                  \
621                 swap_first->field.tqe_prev = &(head1)->tqh_first;       \
622         else                                                            \
623                 (head1)->tqh_last = &(head1)->tqh_first;                \
624         if ((swap_first = (head2)->tqh_first) != NULL)                  \
625                 swap_first->field.tqe_prev = &(head2)->tqh_first;       \
626         else                                                            \
627                 (head2)->tqh_last = &(head2)->tqh_first;                \
628 } while (0)
629
630 #endif /* ROS_KERN_SYS_QUEUE_H */