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user_queue.h (21539B)


      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 * 3. 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 */
     30 
     31 #ifndef _USER_QUEUE_H_
     32 #define	_USER_QUEUE_H_
     33 
     34 /*
     35 * This file defines four types of data structures: singly-linked lists,
     36 * singly-linked tail queues, lists and tail queues.
     37 *
     38 * A singly-linked list is headed by a single forward pointer. The elements
     39 * are singly linked for minimum space and pointer manipulation overhead at
     40 * the expense of O(n) removal for arbitrary elements. New elements can be
     41 * added to the list after an existing element or at the head of the list.
     42 * Elements being removed from the head of the list should use the explicit
     43 * macro for this purpose for optimum efficiency. A singly-linked list may
     44 * only be traversed in the forward direction.  Singly-linked lists are ideal
     45 * for applications with large datasets and few or no removals or for
     46 * implementing a LIFO queue.
     47 *
     48 * A singly-linked tail queue is headed by a pair of pointers, one to the
     49 * head of the list and the other to the tail of the list. The elements are
     50 * singly linked for minimum space and pointer manipulation overhead at the
     51 * expense of O(n) removal for arbitrary elements. New elements can be added
     52 * to the list after an existing element, at the head of the list, or at the
     53 * end of the list. Elements being removed from the head of the tail queue
     54 * should use the explicit macro for this purpose for optimum efficiency.
     55 * A singly-linked tail queue may only be traversed in the forward direction.
     56 * Singly-linked tail queues are ideal for applications with large datasets
     57 * and few or no removals or for implementing a FIFO queue.
     58 *
     59 * A list is headed by a single forward pointer (or an array of forward
     60 * pointers for a hash table header). The elements are doubly linked
     61 * so that an arbitrary element can be removed without a need to
     62 * traverse the list. New elements can be added to the list before
     63 * or after an existing element or at the head of the list. A list
     64 * may only be traversed in the forward direction.
     65 *
     66 * A tail queue is headed by a pair of pointers, one to the head of the
     67 * list and the other to the tail of the list. The elements are doubly
     68 * linked so that an arbitrary element can be removed without a need to
     69 * traverse the list. New elements can be added to the list before or
     70 * after an existing element, at the head of the list, or at the end of
     71 * the list. A tail queue may be traversed in either direction.
     72 *
     73 * For details on the use of these macros, see the queue(3) manual page.
     74 *
     75 *
     76 *				SLIST	LIST	STAILQ	TAILQ
     77 * _HEAD			+	+	+	+
     78 * _HEAD_INITIALIZER		+	+	+	+
     79 * _ENTRY			+	+	+	+
     80 * _INIT			+	+	+	+
     81 * _EMPTY			+	+	+	+
     82 * _FIRST			+	+	+	+
     83 * _NEXT			+	+	+	+
     84 * _PREV			-	-	-	+
     85 * _LAST			-	-	+	+
     86 * _FOREACH			+	+	+	+
     87 * _FOREACH_SAFE		+	+	+	+
     88 * _FOREACH_REVERSE		-	-	-	+
     89 * _FOREACH_REVERSE_SAFE	-	-	-	+
     90 * _INSERT_HEAD			+	+	+	+
     91 * _INSERT_BEFORE		-	+	-	+
     92 * _INSERT_AFTER		+	+	+	+
     93 * _INSERT_TAIL			-	-	+	+
     94 * _CONCAT			-	-	+	+
     95 * _REMOVE_AFTER		+	-	+	-
     96 * _REMOVE_HEAD			+	-	+	-
     97 * _REMOVE			+	+	+	+
     98 * _SWAP			+	+	+	+
     99 *
    100 */
    101 #ifdef QUEUE_MACRO_DEBUG
    102 /* Store the last 2 places the queue element or head was altered */
    103 struct qm_trace {
    104 char * lastfile;
    105 int lastline;
    106 char * prevfile;
    107 int prevline;
    108 };
    109 
    110 #define	TRACEBUF	struct qm_trace trace;
    111 #define	TRASHIT(x)	do {(x) = (void *)-1;} while (0)
    112 #define	QMD_SAVELINK(name, link)	void **name = (void *)&(link)
    113 
    114 #define	QMD_TRACE_HEAD(head) do {					\
    115 (head)->trace.prevline = (head)->trace.lastline;		\
    116 (head)->trace.prevfile = (head)->trace.lastfile;		\
    117 (head)->trace.lastline = __LINE__;				\
    118 (head)->trace.lastfile = __FILE__;				\
    119 } while (0)
    120 
    121 #define	QMD_TRACE_ELEM(elem) do {					\
    122 (elem)->trace.prevline = (elem)->trace.lastline;		\
    123 (elem)->trace.prevfile = (elem)->trace.lastfile;		\
    124 (elem)->trace.lastline = __LINE__;				\
    125 (elem)->trace.lastfile = __FILE__;				\
    126 } while (0)
    127 
    128 #else
    129 #define	QMD_TRACE_ELEM(elem)
    130 #define	QMD_TRACE_HEAD(head)
    131 #define	QMD_SAVELINK(name, link)
    132 #define	TRACEBUF
    133 #define	TRASHIT(x)
    134 #endif	/* QUEUE_MACRO_DEBUG */
    135 
    136 /*
    137 * Singly-linked List declarations.
    138 */
    139 #define	SLIST_HEAD(name, type)						\
    140 struct name {								\
    141 struct type *slh_first;	/* first element */			\
    142 }
    143 
    144 #define	SLIST_HEAD_INITIALIZER(head)					\
    145 { NULL }
    146 
    147 #if defined(_WIN32)
    148 #if defined(SLIST_ENTRY)
    149 #undef SLIST_ENTRY
    150 #endif
    151 #endif
    152 
    153 #define	SLIST_ENTRY(type)						\
    154 struct {								\
    155 struct type *sle_next;	/* next element */			\
    156 }
    157 
    158 /*
    159 * Singly-linked List functions.
    160 */
    161 #define	SLIST_EMPTY(head)	((head)->slh_first == NULL)
    162 
    163 #define	SLIST_FIRST(head)	((head)->slh_first)
    164 
    165 #define	SLIST_FOREACH(var, head, field)					\
    166 for ((var) = SLIST_FIRST((head));				\
    167     (var);							\
    168     (var) = SLIST_NEXT((var), field))
    169 
    170 #define	SLIST_FOREACH_SAFE(var, head, field, tvar)			\
    171 for ((var) = SLIST_FIRST((head));				\
    172     (var) && ((tvar) = SLIST_NEXT((var), field), 1);		\
    173     (var) = (tvar))
    174 
    175 #define	SLIST_FOREACH_PREVPTR(var, varp, head, field)			\
    176 for ((varp) = &SLIST_FIRST((head));				\
    177     ((var) = *(varp)) != NULL;					\
    178     (varp) = &SLIST_NEXT((var), field))
    179 
    180 #define	SLIST_INIT(head) do {						\
    181 SLIST_FIRST((head)) = NULL;					\
    182 } while (0)
    183 
    184 #define	SLIST_INSERT_AFTER(slistelm, elm, field) do {			\
    185 SLIST_NEXT((elm), field) = SLIST_NEXT((slistelm), field);	\
    186 SLIST_NEXT((slistelm), field) = (elm);				\
    187 } while (0)
    188 
    189 #define	SLIST_INSERT_HEAD(head, elm, field) do {			\
    190 SLIST_NEXT((elm), field) = SLIST_FIRST((head));			\
    191 SLIST_FIRST((head)) = (elm);					\
    192 } while (0)
    193 
    194 #define	SLIST_NEXT(elm, field)	((elm)->field.sle_next)
    195 
    196 #define	SLIST_REMOVE(head, elm, type, field) do {			\
    197 QMD_SAVELINK(oldnext, (elm)->field.sle_next);			\
    198 if (SLIST_FIRST((head)) == (elm)) {				\
    199 	SLIST_REMOVE_HEAD((head), field);			\
    200 }								\
    201 else {								\
    202 	struct type *curelm = SLIST_FIRST((head));		\
    203 	while (SLIST_NEXT(curelm, field) != (elm))		\
    204 		curelm = SLIST_NEXT(curelm, field);		\
    205 	SLIST_REMOVE_AFTER(curelm, field);			\
    206 }								\
    207 TRASHIT(*oldnext);						\
    208 } while (0)
    209 
    210 #define SLIST_REMOVE_AFTER(elm, field) do {				\
    211 SLIST_NEXT(elm, field) =					\
    212     SLIST_NEXT(SLIST_NEXT(elm, field), field);			\
    213 } while (0)
    214 
    215 #define	SLIST_REMOVE_HEAD(head, field) do {				\
    216 SLIST_FIRST((head)) = SLIST_NEXT(SLIST_FIRST((head)), field);	\
    217 } while (0)
    218 
    219 #define SLIST_SWAP(head1, head2, type) do {				\
    220 struct type *swap_first = SLIST_FIRST(head1);			\
    221 SLIST_FIRST(head1) = SLIST_FIRST(head2);			\
    222 SLIST_FIRST(head2) = swap_first;				\
    223 } while (0)
    224 
    225 /*
    226 * Singly-linked Tail queue declarations.
    227 */
    228 #define	STAILQ_HEAD(name, type)						\
    229 struct name {								\
    230 struct type *stqh_first;/* first element */			\
    231 struct type **stqh_last;/* addr of last next element */		\
    232 }
    233 
    234 #define	STAILQ_HEAD_INITIALIZER(head)					\
    235 { NULL, &(head).stqh_first }
    236 
    237 #define	STAILQ_ENTRY(type)						\
    238 struct {								\
    239 struct type *stqe_next;	/* next element */			\
    240 }
    241 
    242 /*
    243 * Singly-linked Tail queue functions.
    244 */
    245 #define	STAILQ_CONCAT(head1, head2) do {				\
    246 if (!STAILQ_EMPTY((head2))) {					\
    247 	*(head1)->stqh_last = (head2)->stqh_first;		\
    248 	(head1)->stqh_last = (head2)->stqh_last;		\
    249 	STAILQ_INIT((head2));					\
    250 }								\
    251 } while (0)
    252 
    253 #define	STAILQ_EMPTY(head)	((head)->stqh_first == NULL)
    254 
    255 #define	STAILQ_FIRST(head)	((head)->stqh_first)
    256 
    257 #define	STAILQ_FOREACH(var, head, field)				\
    258 for((var) = STAILQ_FIRST((head));				\
    259    (var);							\
    260    (var) = STAILQ_NEXT((var), field))
    261 
    262 
    263 #define	STAILQ_FOREACH_SAFE(var, head, field, tvar)			\
    264 for ((var) = STAILQ_FIRST((head));				\
    265     (var) && ((tvar) = STAILQ_NEXT((var), field), 1);		\
    266     (var) = (tvar))
    267 
    268 #define	STAILQ_INIT(head) do {						\
    269 STAILQ_FIRST((head)) = NULL;					\
    270 (head)->stqh_last = &STAILQ_FIRST((head));			\
    271 } while (0)
    272 
    273 #define	STAILQ_INSERT_AFTER(head, tqelm, elm, field) do {		\
    274 if ((STAILQ_NEXT((elm), field) = STAILQ_NEXT((tqelm), field)) == NULL)\
    275 	(head)->stqh_last = &STAILQ_NEXT((elm), field);		\
    276 STAILQ_NEXT((tqelm), field) = (elm);				\
    277 } while (0)
    278 
    279 #define	STAILQ_INSERT_HEAD(head, elm, field) do {			\
    280 if ((STAILQ_NEXT((elm), field) = STAILQ_FIRST((head))) == NULL)	\
    281 	(head)->stqh_last = &STAILQ_NEXT((elm), field);		\
    282 STAILQ_FIRST((head)) = (elm);					\
    283 } while (0)
    284 
    285 #define	STAILQ_INSERT_TAIL(head, elm, field) do {			\
    286 STAILQ_NEXT((elm), field) = NULL;				\
    287 *(head)->stqh_last = (elm);					\
    288 (head)->stqh_last = &STAILQ_NEXT((elm), field);			\
    289 } while (0)
    290 
    291 #define	STAILQ_LAST(head, type, field)					\
    292 (STAILQ_EMPTY((head)) ?						\
    293 	NULL :							\
    294         ((struct type *)(void *)				\
    295 	((char *)((head)->stqh_last) - __offsetof(struct type, field))))
    296 
    297 #define	STAILQ_NEXT(elm, field)	((elm)->field.stqe_next)
    298 
    299 #define	STAILQ_REMOVE(head, elm, type, field) do {			\
    300 QMD_SAVELINK(oldnext, (elm)->field.stqe_next);			\
    301 if (STAILQ_FIRST((head)) == (elm)) {				\
    302 	STAILQ_REMOVE_HEAD((head), field);			\
    303 }								\
    304 else {								\
    305 	struct type *curelm = STAILQ_FIRST((head));		\
    306 	while (STAILQ_NEXT(curelm, field) != (elm))		\
    307 		curelm = STAILQ_NEXT(curelm, field);		\
    308 	STAILQ_REMOVE_AFTER(head, curelm, field);		\
    309 }								\
    310 TRASHIT(*oldnext);						\
    311 } while (0)
    312 
    313 #define STAILQ_REMOVE_AFTER(head, elm, field) do {			\
    314 if ((STAILQ_NEXT(elm, field) =					\
    315      STAILQ_NEXT(STAILQ_NEXT(elm, field), field)) == NULL)	\
    316 	(head)->stqh_last = &STAILQ_NEXT((elm), field);		\
    317 } while (0)
    318 
    319 #define	STAILQ_REMOVE_HEAD(head, field) do {				\
    320 if ((STAILQ_FIRST((head)) =					\
    321      STAILQ_NEXT(STAILQ_FIRST((head)), field)) == NULL)		\
    322 	(head)->stqh_last = &STAILQ_FIRST((head));		\
    323 } while (0)
    324 
    325 #define STAILQ_SWAP(head1, head2, type) do {				\
    326 struct type *swap_first = STAILQ_FIRST(head1);			\
    327 struct type **swap_last = (head1)->stqh_last;			\
    328 STAILQ_FIRST(head1) = STAILQ_FIRST(head2);			\
    329 (head1)->stqh_last = (head2)->stqh_last;			\
    330 STAILQ_FIRST(head2) = swap_first;				\
    331 (head2)->stqh_last = swap_last;					\
    332 if (STAILQ_EMPTY(head1))					\
    333 	(head1)->stqh_last = &STAILQ_FIRST(head1);		\
    334 if (STAILQ_EMPTY(head2))					\
    335 	(head2)->stqh_last = &STAILQ_FIRST(head2);		\
    336 } while (0)
    337 
    338 
    339 /*
    340 * List declarations.
    341 */
    342 #define	LIST_HEAD(name, type)						\
    343 struct name {								\
    344 struct type *lh_first;	/* first element */			\
    345 }
    346 
    347 #define	LIST_HEAD_INITIALIZER(head)					\
    348 { NULL }
    349 
    350 #define	LIST_ENTRY(type)						\
    351 struct {								\
    352 struct type *le_next;	/* next element */			\
    353 struct type **le_prev;	/* address of previous next element */	\
    354 }
    355 
    356 /*
    357 * List functions.
    358 */
    359 
    360 #if defined(INVARIANTS)
    361 #define	QMD_LIST_CHECK_HEAD(head, field) do {					\
    362 if (LIST_FIRST((head)) != NULL &&					\
    363     LIST_FIRST((head))->field.le_prev !=				\
    364      &LIST_FIRST((head)))						\
    365 	panic("Bad list head %p first->prev != head", (void *)(head));	\
    366 } while (0)
    367 
    368 #define	QMD_LIST_CHECK_NEXT(elm, field) do {					\
    369 if (LIST_NEXT((elm), field) != NULL &&					\
    370     LIST_NEXT((elm), field)->field.le_prev !=				\
    371      &((elm)->field.le_next))						\
    372      	panic("Bad link elm %p next->prev != elm", (void *)(elm));	\
    373 } while (0)
    374 
    375 #define	QMD_LIST_CHECK_PREV(elm, field) do {					\
    376 if (*(elm)->field.le_prev != (elm))					\
    377 	panic("Bad link elm %p prev->next != elm", (void *)(elm));	\
    378 } while (0)
    379 #else
    380 #define	QMD_LIST_CHECK_HEAD(head, field)
    381 #define	QMD_LIST_CHECK_NEXT(elm, field)
    382 #define	QMD_LIST_CHECK_PREV(elm, field)
    383 #endif /* (INVARIANTS) */
    384 
    385 #define	LIST_EMPTY(head)	((head)->lh_first == NULL)
    386 
    387 #define	LIST_FIRST(head)	((head)->lh_first)
    388 
    389 #define	LIST_FOREACH(var, head, field)					\
    390 for ((var) = LIST_FIRST((head));				\
    391     (var);							\
    392     (var) = LIST_NEXT((var), field))
    393 
    394 #define	LIST_FOREACH_SAFE(var, head, field, tvar)			\
    395 for ((var) = LIST_FIRST((head));				\
    396     (var) && ((tvar) = LIST_NEXT((var), field), 1);		\
    397     (var) = (tvar))
    398 
    399 #define	LIST_INIT(head) do {						\
    400 LIST_FIRST((head)) = NULL;					\
    401 } while (0)
    402 
    403 #define	LIST_INSERT_AFTER(listelm, elm, field) do {			\
    404 QMD_LIST_CHECK_NEXT(listelm, field);				\
    405 if ((LIST_NEXT((elm), field) = LIST_NEXT((listelm), field)) != NULL)\
    406 	LIST_NEXT((listelm), field)->field.le_prev =		\
    407 	    &LIST_NEXT((elm), field);				\
    408 LIST_NEXT((listelm), field) = (elm);				\
    409 (elm)->field.le_prev = &LIST_NEXT((listelm), field);		\
    410 } while (0)
    411 
    412 #define	LIST_INSERT_BEFORE(listelm, elm, field) do {			\
    413 QMD_LIST_CHECK_PREV(listelm, field);				\
    414 (elm)->field.le_prev = (listelm)->field.le_prev;		\
    415 LIST_NEXT((elm), field) = (listelm);				\
    416 *(listelm)->field.le_prev = (elm);				\
    417 (listelm)->field.le_prev = &LIST_NEXT((elm), field);		\
    418 } while (0)
    419 
    420 #define	LIST_INSERT_HEAD(head, elm, field) do {				\
    421 QMD_LIST_CHECK_HEAD((head), field);				\
    422 if ((LIST_NEXT((elm), field) = LIST_FIRST((head))) != NULL)	\
    423 	LIST_FIRST((head))->field.le_prev = &LIST_NEXT((elm), field);\
    424 LIST_FIRST((head)) = (elm);					\
    425 (elm)->field.le_prev = &LIST_FIRST((head));			\
    426 } while (0)
    427 
    428 #define	LIST_NEXT(elm, field)	((elm)->field.le_next)
    429 
    430 #define	LIST_REMOVE(elm, field) do {					\
    431 QMD_SAVELINK(oldnext, (elm)->field.le_next);			\
    432 QMD_SAVELINK(oldprev, (elm)->field.le_prev);			\
    433 QMD_LIST_CHECK_NEXT(elm, field);				\
    434 QMD_LIST_CHECK_PREV(elm, field);				\
    435 if (LIST_NEXT((elm), field) != NULL)				\
    436 	LIST_NEXT((elm), field)->field.le_prev = 		\
    437 	    (elm)->field.le_prev;				\
    438 *(elm)->field.le_prev = LIST_NEXT((elm), field);		\
    439 TRASHIT(*oldnext);						\
    440 TRASHIT(*oldprev);						\
    441 } while (0)
    442 
    443 #define LIST_SWAP(head1, head2, type, field) do {			\
    444 struct type *swap_tmp = LIST_FIRST((head1));			\
    445 LIST_FIRST((head1)) = LIST_FIRST((head2));			\
    446 LIST_FIRST((head2)) = swap_tmp;					\
    447 if ((swap_tmp = LIST_FIRST((head1))) != NULL)			\
    448 	swap_tmp->field.le_prev = &LIST_FIRST((head1));		\
    449 if ((swap_tmp = LIST_FIRST((head2))) != NULL)			\
    450 	swap_tmp->field.le_prev = &LIST_FIRST((head2));		\
    451 } while (0)
    452 
    453 /*
    454 * Tail queue declarations.
    455 */
    456 #define	TAILQ_HEAD(name, type)						\
    457 struct name {								\
    458 struct type *tqh_first;	/* first element */			\
    459 struct type **tqh_last;	/* addr of last next element */		\
    460 TRACEBUF							\
    461 }
    462 
    463 #define	TAILQ_HEAD_INITIALIZER(head)					\
    464 { NULL, &(head).tqh_first }
    465 
    466 #define	TAILQ_ENTRY(type)						\
    467 struct {								\
    468 struct type *tqe_next;	/* next element */			\
    469 struct type **tqe_prev;	/* address of previous next element */	\
    470 TRACEBUF							\
    471 }
    472 
    473 /*
    474 * Tail queue functions.
    475 */
    476 #if defined(INVARIANTS)
    477 #define	QMD_TAILQ_CHECK_HEAD(head, field) do {					\
    478 if (!TAILQ_EMPTY(head) &&						\
    479     TAILQ_FIRST((head))->field.tqe_prev !=				\
    480      &TAILQ_FIRST((head)))						\
    481 	panic("Bad tailq head %p first->prev != head", (void *)(head));	\
    482 } while (0)
    483 
    484 #define	QMD_TAILQ_CHECK_TAIL(head, field) do {					\
    485 if (*(head)->tqh_last != NULL)						\
    486     	panic("Bad tailq NEXT(%p->tqh_last) != NULL", (void *)(head)); 	\
    487 } while (0)
    488 
    489 #define	QMD_TAILQ_CHECK_NEXT(elm, field) do {					\
    490 if (TAILQ_NEXT((elm), field) != NULL &&					\
    491     TAILQ_NEXT((elm), field)->field.tqe_prev !=				\
    492      &((elm)->field.tqe_next))						\
    493 	panic("Bad link elm %p next->prev != elm", (void *)(elm));	\
    494 } while (0)
    495 
    496 #define	QMD_TAILQ_CHECK_PREV(elm, field) do {					\
    497 if (*(elm)->field.tqe_prev != (elm))					\
    498 	panic("Bad link elm %p prev->next != elm", (void *)(elm));	\
    499 } while (0)
    500 #else
    501 #define	QMD_TAILQ_CHECK_HEAD(head, field)
    502 #define	QMD_TAILQ_CHECK_TAIL(head, headname)
    503 #define	QMD_TAILQ_CHECK_NEXT(elm, field)
    504 #define	QMD_TAILQ_CHECK_PREV(elm, field)
    505 #endif /* (INVARIANTS) */
    506 
    507 #define	TAILQ_CONCAT(head1, head2, field) do {				\
    508 if (!TAILQ_EMPTY(head2)) {					\
    509 	*(head1)->tqh_last = (head2)->tqh_first;		\
    510 	(head2)->tqh_first->field.tqe_prev = (head1)->tqh_last;	\
    511 	(head1)->tqh_last = (head2)->tqh_last;			\
    512 	TAILQ_INIT((head2));					\
    513 	QMD_TRACE_HEAD(head1);					\
    514 	QMD_TRACE_HEAD(head2);					\
    515 }								\
    516 } while (0)
    517 
    518 #define	TAILQ_EMPTY(head)	((head)->tqh_first == NULL)
    519 
    520 #define	TAILQ_FIRST(head)	((head)->tqh_first)
    521 
    522 #define	TAILQ_FOREACH(var, head, field)					\
    523 for ((var) = TAILQ_FIRST((head));				\
    524     (var);							\
    525     (var) = TAILQ_NEXT((var), field))
    526 
    527 #define	TAILQ_FOREACH_SAFE(var, head, field, tvar)			\
    528 for ((var) = TAILQ_FIRST((head));				\
    529     (var) && ((tvar) = TAILQ_NEXT((var), field), 1);		\
    530     (var) = (tvar))
    531 
    532 #define	TAILQ_FOREACH_REVERSE(var, head, headname, field)		\
    533 for ((var) = TAILQ_LAST((head), headname);			\
    534     (var);							\
    535     (var) = TAILQ_PREV((var), headname, field))
    536 
    537 #define	TAILQ_FOREACH_REVERSE_SAFE(var, head, headname, field, tvar)	\
    538 for ((var) = TAILQ_LAST((head), headname);			\
    539     (var) && ((tvar) = TAILQ_PREV((var), headname, field), 1);	\
    540     (var) = (tvar))
    541 
    542 #define	TAILQ_INIT(head) do {						\
    543 TAILQ_FIRST((head)) = NULL;					\
    544 (head)->tqh_last = &TAILQ_FIRST((head));			\
    545 QMD_TRACE_HEAD(head);						\
    546 } while (0)
    547 
    548 #define	TAILQ_INSERT_AFTER(head, listelm, elm, field) do {		\
    549 QMD_TAILQ_CHECK_NEXT(listelm, field);				\
    550 if ((TAILQ_NEXT((elm), field) = TAILQ_NEXT((listelm), field)) != NULL)\
    551 	TAILQ_NEXT((elm), field)->field.tqe_prev = 		\
    552 	    &TAILQ_NEXT((elm), field);				\
    553 else {								\
    554 	(head)->tqh_last = &TAILQ_NEXT((elm), field);		\
    555 	QMD_TRACE_HEAD(head);					\
    556 }								\
    557 TAILQ_NEXT((listelm), field) = (elm);				\
    558 (elm)->field.tqe_prev = &TAILQ_NEXT((listelm), field);		\
    559 QMD_TRACE_ELEM(&(elm)->field);					\
    560 QMD_TRACE_ELEM(&listelm->field);				\
    561 } while (0)
    562 
    563 #define	TAILQ_INSERT_BEFORE(listelm, elm, field) do {			\
    564 QMD_TAILQ_CHECK_PREV(listelm, field);				\
    565 (elm)->field.tqe_prev = (listelm)->field.tqe_prev;		\
    566 TAILQ_NEXT((elm), field) = (listelm);				\
    567 *(listelm)->field.tqe_prev = (elm);				\
    568 (listelm)->field.tqe_prev = &TAILQ_NEXT((elm), field);		\
    569 QMD_TRACE_ELEM(&(elm)->field);					\
    570 QMD_TRACE_ELEM(&listelm->field);				\
    571 } while (0)
    572 
    573 #define	TAILQ_INSERT_HEAD(head, elm, field) do {			\
    574 QMD_TAILQ_CHECK_HEAD(head, field);				\
    575 if ((TAILQ_NEXT((elm), field) = TAILQ_FIRST((head))) != NULL)	\
    576 	TAILQ_FIRST((head))->field.tqe_prev =			\
    577 	    &TAILQ_NEXT((elm), field);				\
    578 else								\
    579 	(head)->tqh_last = &TAILQ_NEXT((elm), field);		\
    580 TAILQ_FIRST((head)) = (elm);					\
    581 (elm)->field.tqe_prev = &TAILQ_FIRST((head));			\
    582 QMD_TRACE_HEAD(head);						\
    583 QMD_TRACE_ELEM(&(elm)->field);					\
    584 } while (0)
    585 
    586 #define	TAILQ_INSERT_TAIL(head, elm, field) do {			\
    587 QMD_TAILQ_CHECK_TAIL(head, field);				\
    588 TAILQ_NEXT((elm), field) = NULL;				\
    589 (elm)->field.tqe_prev = (head)->tqh_last;			\
    590 *(head)->tqh_last = (elm);					\
    591 (head)->tqh_last = &TAILQ_NEXT((elm), field);			\
    592 QMD_TRACE_HEAD(head);						\
    593 QMD_TRACE_ELEM(&(elm)->field);					\
    594 } while (0)
    595 
    596 #define	TAILQ_LAST(head, headname)					\
    597 (*(((struct headname *)((head)->tqh_last))->tqh_last))
    598 
    599 #define	TAILQ_NEXT(elm, field) ((elm)->field.tqe_next)
    600 
    601 #define	TAILQ_PREV(elm, headname, field)				\
    602 (*(((struct headname *)((elm)->field.tqe_prev))->tqh_last))
    603 
    604 #define	TAILQ_REMOVE(head, elm, field) do {				\
    605 QMD_SAVELINK(oldnext, (elm)->field.tqe_next);			\
    606 QMD_SAVELINK(oldprev, (elm)->field.tqe_prev);			\
    607 QMD_TAILQ_CHECK_NEXT(elm, field);				\
    608 QMD_TAILQ_CHECK_PREV(elm, field);				\
    609 if ((TAILQ_NEXT((elm), field)) != NULL)				\
    610 	TAILQ_NEXT((elm), field)->field.tqe_prev = 		\
    611 	    (elm)->field.tqe_prev;				\
    612 else {								\
    613 	(head)->tqh_last = (elm)->field.tqe_prev;		\
    614 	QMD_TRACE_HEAD(head);					\
    615 }								\
    616 *(elm)->field.tqe_prev = TAILQ_NEXT((elm), field);		\
    617 TRASHIT(*oldnext);						\
    618 TRASHIT(*oldprev);						\
    619 QMD_TRACE_ELEM(&(elm)->field);					\
    620 } while (0)
    621 
    622 #define TAILQ_SWAP(head1, head2, type, field) do {			\
    623 struct type *swap_first = (head1)->tqh_first;			\
    624 struct type **swap_last = (head1)->tqh_last;			\
    625 (head1)->tqh_first = (head2)->tqh_first;			\
    626 (head1)->tqh_last = (head2)->tqh_last;				\
    627 (head2)->tqh_first = swap_first;				\
    628 (head2)->tqh_last = swap_last;					\
    629 if ((swap_first = (head1)->tqh_first) != NULL)			\
    630 	swap_first->field.tqe_prev = &(head1)->tqh_first;	\
    631 else								\
    632 	(head1)->tqh_last = &(head1)->tqh_first;		\
    633 if ((swap_first = (head2)->tqh_first) != NULL)			\
    634 	swap_first->field.tqe_prev = &(head2)->tqh_first;	\
    635 else								\
    636 	(head2)->tqh_last = &(head2)->tqh_first;		\
    637 } while (0)
    638 
    639 #endif /* !_SYS_QUEUE_H_ */