sys/kern/subr_taskqueue.c

   1 /*-
   2  * Copyright (c) 2000 Doug Rabson
   3  * 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  *
  14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  15  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  16  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  17  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  18  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  19  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  20  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  21  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  22  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  23  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  24  * SUCH DAMAGE.
  25  */
  26
  27 #include <sys/cdefs.h>
  28 __FBSDID("$FreeBSD$");
  29
  30 #include <sys/param.h>
  31 #include <sys/systm.h>
  32 #include <sys/bus.h>
  33 #include <sys/cpuset.h>
  34 #include <sys/interrupt.h>
  35 #include <sys/kernel.h>
  36 #include <sys/kthread.h>
  37 #include <sys/limits.h>
  38 #include <sys/lock.h>
  39 #include <sys/malloc.h>
  40 #include <sys/mutex.h>
  41 #include <sys/proc.h>
  42 #include <sys/sched.h>
  43 #include <sys/taskqueue.h>
  44 #include <sys/unistd.h>
  45 #include <machine/stdarg.h>
  46
  47 static MALLOC_DEFINE(M_TASKQUEUE, "taskqueue", "Task Queues");
  48 static void     *taskqueue_giant_ih;
  49 static void     *taskqueue_ih;
  50 static void      taskqueue_fast_enqueue(void *);
  51 static void      taskqueue_swi_enqueue(void *);
  52 static void      taskqueue_swi_giant_enqueue(void *);
  53
  54 struct taskqueue_busy {
  55         struct task     *tb_running;
  56         TAILQ_ENTRY(taskqueue_busy) tb_link;
  57 };
  58
  59 struct taskqueue {
  60         STAILQ_HEAD(, task)     tq_queue;
  61         taskqueue_enqueue_fn    tq_enqueue;
  62         void                    *tq_context;
  63         TAILQ_HEAD(, taskqueue_busy) tq_active;
  64         struct mtx              tq_mutex;
  65         struct thread           **tq_threads;
  66         int                     tq_tcount;
  67         int                     tq_spin;
  68         int                     tq_flags;
  69         int                     tq_callouts;
  70         taskqueue_callback_fn   tq_callbacks[TASKQUEUE_NUM_CALLBACKS];
  71         void                    *tq_cb_contexts[TASKQUEUE_NUM_CALLBACKS];
  72 };
  73
  74 #define TQ_FLAGS_ACTIVE         (1 << 0)
  75 #define TQ_FLAGS_BLOCKED        (1 << 1)
  76 #define TQ_FLAGS_UNLOCKED_ENQUEUE       (1 << 2)
  77
  78 #define DT_CALLOUT_ARMED        (1 << 0)
  79
  80 #define TQ_LOCK(tq)                                                     \
  81         do {                                                            \
  82                 if ((tq)->tq_spin)                                      \
  83                         mtx_lock_spin(&(tq)->tq_mutex);                 \
  84                 else                                                    \
  85                         mtx_lock(&(tq)->tq_mutex);                      \
  86         } while (0)
  87 #define TQ_ASSERT_LOCKED(tq)    mtx_assert(&(tq)->tq_mutex, MA_OWNED)
  88
  89 #define TQ_UNLOCK(tq)                                                   \
  90         do {                                                            \
  91                 if ((tq)->tq_spin)                                      \
  92                         mtx_unlock_spin(&(tq)->tq_mutex);               \
  93                 else                                                    \
  94                         mtx_unlock(&(tq)->tq_mutex);                    \
  95         } while (0)
  96 #define TQ_ASSERT_UNLOCKED(tq)  mtx_assert(&(tq)->tq_mutex, MA_NOTOWNED)
  97
  98 void
  99 _timeout_task_init(struct taskqueue *queue, struct timeout_task *timeout_task,
 100     int priority, task_fn_t func, void *context)
 101 {
 102
 103         TASK_INIT(&timeout_task->t, priority, func, context);
 104         callout_init_mtx(&timeout_task->c, &queue->tq_mutex,
 105             CALLOUT_RETURNUNLOCKED);
 106         timeout_task->q = queue;
 107         timeout_task->f = 0;
 108 }
 109
 110 static __inline int
 111 TQ_SLEEP(struct taskqueue *tq, void *p, struct mtx *m, int pri, const char *wm,
 112     int t)
 113 {
 114         if (tq->tq_spin)
 115                 return (msleep_spin(p, m, wm, t));
 116         return (msleep(p, m, pri, wm, t));
 117 }
 118
 119 static struct taskqueue *
 120 _taskqueue_create(const char *name __unused, int mflags,
 121                  taskqueue_enqueue_fn enqueue, void *context,
 122                  int mtxflags, const char *mtxname)
 123 {
 124         struct taskqueue *queue;
 125
 126         queue = malloc(sizeof(struct taskqueue), M_TASKQUEUE, mflags | M_ZERO);
 127         if (!queue)
 128                 return NULL;
 129
 130         STAILQ_INIT(&queue->tq_queue);
 131         TAILQ_INIT(&queue->tq_active);
 132         queue->tq_enqueue = enqueue;
 133         queue->tq_context = context;
 134         queue->tq_spin = (mtxflags & MTX_SPIN) != 0;
 135         queue->tq_flags |= TQ_FLAGS_ACTIVE;
 136         if (enqueue == taskqueue_fast_enqueue ||
 137             enqueue == taskqueue_swi_enqueue ||
 138             enqueue == taskqueue_swi_giant_enqueue ||
 139             enqueue == taskqueue_thread_enqueue)
 140                 queue->tq_flags |= TQ_FLAGS_UNLOCKED_ENQUEUE;
 141         mtx_init(&queue->tq_mutex, mtxname, NULL, mtxflags);
 142
 143         return queue;
 144 }
 145
 146 struct taskqueue *
 147 taskqueue_create(const char *name, int mflags,
 148                  taskqueue_enqueue_fn enqueue, void *context)
 149 {
 150         return _taskqueue_create(name, mflags, enqueue, context,
 151                         MTX_DEF, "taskqueue");
 152 }
 153
 154 void
 155 taskqueue_set_callback(struct taskqueue *queue,
 156     enum taskqueue_callback_type cb_type, taskqueue_callback_fn callback,
 157     void *context)
 158 {
 159
 160         KASSERT(((cb_type >= TASKQUEUE_CALLBACK_TYPE_MIN) &&
 161             (cb_type <= TASKQUEUE_CALLBACK_TYPE_MAX)),
 162             ("Callback type %d not valid, must be %d-%d", cb_type,
 163             TASKQUEUE_CALLBACK_TYPE_MIN, TASKQUEUE_CALLBACK_TYPE_MAX));
 164         KASSERT((queue->tq_callbacks[cb_type] == NULL),
 165             ("Re-initialization of taskqueue callback?"));
 166
 167         queue->tq_callbacks[cb_type] = callback;
 168         queue->tq_cb_contexts[cb_type] = context;
 169 }
 170
 171 /*
 172  * Signal a taskqueue thread to terminate.
 173  */
 174 static void
 175 taskqueue_terminate(struct thread **pp, struct taskqueue *tq)
 176 {
 177
 178         while (tq->tq_tcount > 0 || tq->tq_callouts > 0) {
 179                 wakeup(tq);
 180                 TQ_SLEEP(tq, pp, &tq->tq_mutex, PWAIT, "taskqueue_destroy", 0);
 181         }
 182 }
 183
 184 void
 185 taskqueue_free(struct taskqueue *queue)
 186 {
 187
 188         TQ_LOCK(queue);
 189         queue->tq_flags &= ~TQ_FLAGS_ACTIVE;
 190         taskqueue_terminate(queue->tq_threads, queue);
 191         KASSERT(TAILQ_EMPTY(&queue->tq_active), ("Tasks still running?"));
 192         KASSERT(queue->tq_callouts == 0, ("Armed timeout tasks"));
 193         mtx_destroy(&queue->tq_mutex);
 194         free(queue->tq_threads, M_TASKQUEUE);
 195         free(queue, M_TASKQUEUE);
 196 }
 197
 198 static int
 199 taskqueue_enqueue_locked(struct taskqueue *queue, struct task *task)
 200 {
 201         struct task *ins;
 202         struct task *prev;
 203
 204         /*
 205          * Count multiple enqueues.
 206          */
 207         if (task->ta_pending) {
 208                 if (task->ta_pending < USHRT_MAX)
 209                         task->ta_pending++;
 210                 TQ_UNLOCK(queue);
 211                 return (0);
 212         }
 213
 214         /*
 215          * Optimise the case when all tasks have the same priority.
 216          */
 217         prev = STAILQ_LAST(&queue->tq_queue, task, ta_link);
 218         if (!prev || prev->ta_priority >= task->ta_priority) {
 219                 STAILQ_INSERT_TAIL(&queue->tq_queue, task, ta_link);
 220         } else {
 221                 prev = NULL;
 222                 for (ins = STAILQ_FIRST(&queue->tq_queue); ins;
 223                      prev = ins, ins = STAILQ_NEXT(ins, ta_link))
 224                         if (ins->ta_priority < task->ta_priority)
 225                                 break;
 226
 227                 if (prev)
 228                         STAILQ_INSERT_AFTER(&queue->tq_queue, prev, task, ta_link);
 229                 else
 230                         STAILQ_INSERT_HEAD(&queue->tq_queue, task, ta_link);
 231         }
 232
 233         task->ta_pending = 1;
 234         if ((queue->tq_flags & TQ_FLAGS_UNLOCKED_ENQUEUE) != 0)
 235                 TQ_UNLOCK(queue);
 236         if ((queue->tq_flags & TQ_FLAGS_BLOCKED) == 0)
 237                 queue->tq_enqueue(queue->tq_context);
 238         if ((queue->tq_flags & TQ_FLAGS_UNLOCKED_ENQUEUE) == 0)
 239                 TQ_UNLOCK(queue);
 240
 241         /* Return with lock released. */
 242         return (0);
 243 }
 244 int
 245 taskqueue_enqueue(struct taskqueue *queue, struct task *task)
 246 {
 247         int res;
 248
 249         TQ_LOCK(queue);
 250         res = taskqueue_enqueue_locked(queue, task);
 251         /* The lock is released inside. */
 252
 253         return (res);
 254 }
 255
 256 static void
 257 taskqueue_timeout_func(void *arg)
 258 {
 259         struct taskqueue *queue;
 260         struct timeout_task *timeout_task;
 261
 262         timeout_task = arg;
 263         queue = timeout_task->q;
 264         KASSERT((timeout_task->f & DT_CALLOUT_ARMED) != 0, ("Stray timeout"));
 265         timeout_task->f &= ~DT_CALLOUT_ARMED;
 266         queue->tq_callouts--;
 267         taskqueue_enqueue_locked(timeout_task->q, &timeout_task->t);
 268         /* The lock is released inside. */
 269 }
 270
 271 int
 272 taskqueue_enqueue_timeout(struct taskqueue *queue,
 273     struct timeout_task *timeout_task, int ticks)
 274 {
 275         int res;
 276
 277         TQ_LOCK(queue);
 278         KASSERT(timeout_task->q == NULL || timeout_task->q == queue,
 279             ("Migrated queue"));
 280         KASSERT(!queue->tq_spin, ("Timeout for spin-queue"));
 281         timeout_task->q = queue;
 282         res = timeout_task->t.ta_pending;
 283         if (ticks == 0) {
 284                 taskqueue_enqueue_locked(queue, &timeout_task->t);
 285                 /* The lock is released inside. */
 286         } else {
 287                 if ((timeout_task->f & DT_CALLOUT_ARMED) != 0) {
 288                         res++;
 289                 } else {
 290                         queue->tq_callouts++;
 291                         timeout_task->f |= DT_CALLOUT_ARMED;
 292                         if (ticks < 0)
 293                                 ticks = -ticks; /* Ignore overflow. */
 294                 }
 295                 if (ticks > 0) {
 296                         callout_reset(&timeout_task->c, ticks,
 297                             taskqueue_timeout_func, timeout_task);
 298                 }
 299                 TQ_UNLOCK(queue);
 300         }
 301         return (res);
 302 }
 303
 304 static void
 305 taskqueue_drain_running(struct taskqueue *queue)
 306 {
 307
 308         while (!TAILQ_EMPTY(&queue->tq_active))
 309                 TQ_SLEEP(queue, &queue->tq_active, &queue->tq_mutex,
 310                     PWAIT, "-", 0);
 311 }
 312
 313 void
 314 taskqueue_block(struct taskqueue *queue)
 315 {
 316
 317         TQ_LOCK(queue);
 318         queue->tq_flags |= TQ_FLAGS_BLOCKED;
 319         TQ_UNLOCK(queue);
 320 }
 321
 322 void
 323 taskqueue_unblock(struct taskqueue *queue)
 324 {
 325
 326         TQ_LOCK(queue);
 327         queue->tq_flags &= ~TQ_FLAGS_BLOCKED;
 328         if (!STAILQ_EMPTY(&queue->tq_queue))
 329                 queue->tq_enqueue(queue->tq_context);
 330         TQ_UNLOCK(queue);
 331 }
 332
 333 static void
 334 taskqueue_run_locked(struct taskqueue *queue)
 335 {
 336         struct taskqueue_busy tb;
 337         struct task *task;
 338         int pending;
 339
 340         TQ_ASSERT_LOCKED(queue);
 341         tb.tb_running = NULL;
 342         TAILQ_INSERT_TAIL(&queue->tq_active, &tb, tb_link);
 343
 344         while (STAILQ_FIRST(&queue->tq_queue)) {
 345                 /*
 346                  * Carefully remove the first task from the queue and
 347                  * zero its pending count.
 348                  */
 349                 task = STAILQ_FIRST(&queue->tq_queue);
 350                 STAILQ_REMOVE_HEAD(&queue->tq_queue, ta_link);
 351                 pending = task->ta_pending;
 352                 task->ta_pending = 0;
 353                 tb.tb_running = task;
 354                 TQ_UNLOCK(queue);
 355
 356                 task->ta_func(task->ta_context, pending);
 357
 358                 TQ_LOCK(queue);
 359                 tb.tb_running = NULL;
 360                 wakeup(task);
 361         }
 362         TAILQ_REMOVE(&queue->tq_active, &tb, tb_link);
 363         if (TAILQ_EMPTY(&queue->tq_active))
 364                 wakeup(&queue->tq_active);
 365 }
 366
 367 void
 368 taskqueue_run(struct taskqueue *queue)
 369 {
 370
 371         TQ_LOCK(queue);
 372         taskqueue_run_locked(queue);
 373         TQ_UNLOCK(queue);
 374 }
 375
 376 static int
 377 task_is_running(struct taskqueue *queue, struct task *task)
 378 {
 379         struct taskqueue_busy *tb;
 380
 381         TQ_ASSERT_LOCKED(queue);
 382         TAILQ_FOREACH(tb, &queue->tq_active, tb_link) {
 383                 if (tb->tb_running == task)
 384                         return (1);
 385         }
 386         return (0);
 387 }
 388
 389 static int
 390 taskqueue_cancel_locked(struct taskqueue *queue, struct task *task,
 391     u_int *pendp)
 392 {
 393
 394         if (task->ta_pending > 0)
 395                 STAILQ_REMOVE(&queue->tq_queue, task, task, ta_link);
 396         if (pendp != NULL)
 397                 *pendp = task->ta_pending;
 398         task->ta_pending = 0;
 399         return (task_is_running(queue, task) ? EBUSY : 0);
 400 }
 401
 402 int
 403 taskqueue_cancel(struct taskqueue *queue, struct task *task, u_int *pendp)
 404 {
 405         int error;
 406
 407         TQ_LOCK(queue);
 408         error = taskqueue_cancel_locked(queue, task, pendp);
 409         TQ_UNLOCK(queue);
 410
 411         return (error);
 412 }
 413
 414 int
 415 taskqueue_cancel_timeout(struct taskqueue *queue,
 416     struct timeout_task *timeout_task, u_int *pendp)
 417 {
 418         u_int pending, pending1;
 419         int error;
 420
 421         TQ_LOCK(queue);
 422         pending = !!callout_stop(&timeout_task->c);
 423         error = taskqueue_cancel_locked(queue, &timeout_task->t, &pending1);
 424         if ((timeout_task->f & DT_CALLOUT_ARMED) != 0) {
 425                 timeout_task->f &= ~DT_CALLOUT_ARMED;
 426                 queue->tq_callouts--;
 427         }
 428         TQ_UNLOCK(queue);
 429
 430         if (pendp != NULL)
 431                 *pendp = pending + pending1;
 432         return (error);
 433 }
 434
 435 void
 436 taskqueue_drain(struct taskqueue *queue, struct task *task)
 437 {
 438
 439         if (!queue->tq_spin)
 440                 WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, NULL, __func__);
 441
 442         TQ_LOCK(queue);
 443         while (task->ta_pending != 0 || task_is_running(queue, task))
 444                 TQ_SLEEP(queue, task, &queue->tq_mutex, PWAIT, "-", 0);
 445         TQ_UNLOCK(queue);
 446 }
 447
 448 void
 449 taskqueue_drain_all(struct taskqueue *queue)
 450 {
 451         struct task *task;
 452
 453         if (!queue->tq_spin)
 454                 WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, NULL, __func__);
 455
 456         TQ_LOCK(queue);
 457         task = STAILQ_LAST(&queue->tq_queue, task, ta_link);
 458         if (task != NULL)
 459                 while (task->ta_pending != 0)
 460                         TQ_SLEEP(queue, task, &queue->tq_mutex, PWAIT, "-", 0);
 461         taskqueue_drain_running(queue);
 462         KASSERT(STAILQ_EMPTY(&queue->tq_queue),
 463             ("taskqueue queue is not empty after draining"));
 464         TQ_UNLOCK(queue);
 465 }
 466
 467 void
 468 taskqueue_drain_timeout(struct taskqueue *queue,
 469     struct timeout_task *timeout_task)
 470 {
 471
 472         callout_drain(&timeout_task->c);
 473         taskqueue_drain(queue, &timeout_task->t);
 474 }
 475
 476 static void
 477 taskqueue_swi_enqueue(void *context)
 478 {
 479         swi_sched(taskqueue_ih, 0);
 480 }
 481
 482 static void
 483 taskqueue_swi_run(void *dummy)
 484 {
 485         taskqueue_run(taskqueue_swi);
 486 }
 487
 488 static void
 489 taskqueue_swi_giant_enqueue(void *context)
 490 {
 491         swi_sched(taskqueue_giant_ih, 0);
 492 }
 493
 494 static void
 495 taskqueue_swi_giant_run(void *dummy)
 496 {
 497         taskqueue_run(taskqueue_swi_giant);
 498 }
 499
 500 static int
 501 _taskqueue_start_threads(struct taskqueue **tqp, int count, int pri,
 502     cpuset_t *mask, const char *ktname)
 503 {
 504         struct thread *td;
 505         struct taskqueue *tq;
 506         int i, error;
 507
 508         if (count <= 0)
 509                 return (EINVAL);
 510
 511         tq = *tqp;
 512
 513         tq->tq_threads = malloc(sizeof(struct thread *) * count, M_TASKQUEUE,
 514             M_NOWAIT | M_ZERO);
 515         if (tq->tq_threads == NULL) {
 516                 printf("%s: no memory for %s threads\n", __func__, ktname);
 517                 return (ENOMEM);
 518         }
 519
 520         for (i = 0; i < count; i++) {
 521                 if (count == 1)
 522                         error = kthread_add(taskqueue_thread_loop, tqp, NULL,
 523                             &tq->tq_threads[i], RFSTOPPED, 0, "%s", ktname);
 524                 else
 525                         error = kthread_add(taskqueue_thread_loop, tqp, NULL,
 526                             &tq->tq_threads[i], RFSTOPPED, 0,
 527                             "%s_%d", ktname, i);
 528                 if (error) {
 529                         /* should be ok to continue, taskqueue_free will dtrt */
 530                         printf("%s: kthread_add(%s): error %d", __func__,
 531                             ktname, error);
 532                         tq->tq_threads[i] = NULL;               /* paranoid */
 533                 } else
 534                         tq->tq_tcount++;
 535         }
 536         for (i = 0; i < count; i++) {
 537                 if (tq->tq_threads[i] == NULL)
 538                         continue;
 539                 td = tq->tq_threads[i];
 540                 if (mask) {
 541                         error = cpuset_setthread(td->td_tid, mask);
 542                         /*
 543                          * Failing to pin is rarely an actual fatal error;
 544                          * it'll just affect performance.
 545                          */
 546                         if (error)
 547                                 printf("%s: curthread=%llu: can't pin; "
 548                                     "error=%d\n",
 549                                     __func__,
 550                                     (unsigned long long) td->td_tid,
 551                                     error);
 552                 }
 553                 thread_lock(td);
 554                 sched_prio(td, pri);
 555                 sched_add(td, SRQ_BORING);
 556                 thread_unlock(td);
 557         }
 558
 559         return (0);
 560 }
 561
 562 int
 563 taskqueue_start_threads(struct taskqueue **tqp, int count, int pri,
 564     const char *name, ...)
 565 {
 566         char ktname[MAXCOMLEN + 1];
 567         va_list ap;
 568
 569         va_start(ap, name);
 570         vsnprintf(ktname, sizeof(ktname), name, ap);
 571         va_end(ap);
 572
 573         return (_taskqueue_start_threads(tqp, count, pri, NULL, ktname));
 574 }
 575
 576 int
 577 taskqueue_start_threads_pinned(struct taskqueue **tqp, int count, int pri,
 578     int cpu_id, const char *name, ...)
 579 {
 580         char ktname[MAXCOMLEN + 1];
 581         va_list ap;
 582         cpuset_t mask;
 583
 584         va_start(ap, name);
 585         vsnprintf(ktname, sizeof(ktname), name, ap);
 586         va_end(ap);
 587
 588         /*
 589          * In case someone passes in NOCPU, just fall back to the
 590          * default behaviour of "don't pin".
 591          */
 592         if (cpu_id != NOCPU) {
 593                 CPU_ZERO(&mask);
 594                 CPU_SET(cpu_id, &mask);
 595         }
 596
 597         return (_taskqueue_start_threads(tqp, count, pri,
 598             cpu_id == NOCPU ? NULL : &mask, ktname));
 599 }
 600
 601 static inline void
 602 taskqueue_run_callback(struct taskqueue *tq,
 603     enum taskqueue_callback_type cb_type)
 604 {
 605         taskqueue_callback_fn tq_callback;
 606
 607         TQ_ASSERT_UNLOCKED(tq);
 608         tq_callback = tq->tq_callbacks[cb_type];
 609         if (tq_callback != NULL)
 610                 tq_callback(tq->tq_cb_contexts[cb_type]);
 611 }
 612
 613 void
 614 taskqueue_thread_loop(void *arg)
 615 {
 616         struct taskqueue **tqp, *tq;
 617
 618         tqp = arg;
 619         tq = *tqp;
 620         taskqueue_run_callback(tq, TASKQUEUE_CALLBACK_TYPE_INIT);
 621         TQ_LOCK(tq);
 622         while ((tq->tq_flags & TQ_FLAGS_ACTIVE) != 0) {
 623                 taskqueue_run_locked(tq);
 624                 /*
 625                  * Because taskqueue_run() can drop tq_mutex, we need to
 626                  * check if the TQ_FLAGS_ACTIVE flag wasn't removed in the
 627                  * meantime, which means we missed a wakeup.
 628                  */
 629                 if ((tq->tq_flags & TQ_FLAGS_ACTIVE) == 0)
 630                         break;
 631                 TQ_SLEEP(tq, tq, &tq->tq_mutex, 0, "-", 0);
 632         }
 633         taskqueue_run_locked(tq);
 634
 635         /*
 636          * This thread is on its way out, so just drop the lock temporarily
 637          * in order to call the shutdown callback.  This allows the callback
 638          * to look at the taskqueue, even just before it dies.
 639          */
 640         TQ_UNLOCK(tq);
 641         taskqueue_run_callback(tq, TASKQUEUE_CALLBACK_TYPE_SHUTDOWN);
 642         TQ_LOCK(tq);
 643
 644         /* rendezvous with thread that asked us to terminate */
 645         tq->tq_tcount--;
 646         wakeup_one(tq->tq_threads);
 647         TQ_UNLOCK(tq);
 648         kthread_exit();
 649 }
 650
 651 void
 652 taskqueue_thread_enqueue(void *context)
 653 {
 654         struct taskqueue **tqp, *tq;
 655
 656         tqp = context;
 657         tq = *tqp;
 658
 659         wakeup_one(tq);
 660 }
 661
 662 TASKQUEUE_DEFINE(swi, taskqueue_swi_enqueue, NULL,
 663                  swi_add(NULL, "task queue", taskqueue_swi_run, NULL, SWI_TQ,
 664                      INTR_MPSAFE, &taskqueue_ih));
 665
 666 TASKQUEUE_DEFINE(swi_giant, taskqueue_swi_giant_enqueue, NULL,
 667                  swi_add(NULL, "Giant taskq", taskqueue_swi_giant_run,
 668                      NULL, SWI_TQ_GIANT, 0, &taskqueue_giant_ih));
 669
 670 TASKQUEUE_DEFINE_THREAD(thread);
 671
 672 struct taskqueue *
 673 taskqueue_create_fast(const char *name, int mflags,
 674                  taskqueue_enqueue_fn enqueue, void *context)
 675 {
 676         return _taskqueue_create(name, mflags, enqueue, context,
 677                         MTX_SPIN, "fast_taskqueue");
 678 }
 679
 680 /* NB: for backwards compatibility */
 681 int
 682 taskqueue_enqueue_fast(struct taskqueue *queue, struct task *task)
 683 {
 684         return taskqueue_enqueue(queue, task);
 685 }
 686
 687 static void     *taskqueue_fast_ih;
 688
 689 static void
 690 taskqueue_fast_enqueue(void *context)
 691 {
 692         swi_sched(taskqueue_fast_ih, 0);
 693 }
 694
 695 static void
 696 taskqueue_fast_run(void *dummy)
 697 {
 698         taskqueue_run(taskqueue_fast);
 699 }
 700
 701 TASKQUEUE_FAST_DEFINE(fast, taskqueue_fast_enqueue, NULL,
 702         swi_add(NULL, "fast taskq", taskqueue_fast_run, NULL,
 703         SWI_TQ_FAST, INTR_MPSAFE, &taskqueue_fast_ih));
 704
 705 int
 706 taskqueue_member(struct taskqueue *queue, struct thread *td)
 707 {
 708         int i, j, ret = 0;
 709
 710         for (i = 0, j = 0; ; i++) {
 711                 if (queue->tq_threads[i] == NULL)
 712                         continue;
 713                 if (queue->tq_threads[i] == td) {
 714                         ret = 1;
 715                         break;
 716                 }
 717                 if (++j >= queue->tq_tcount)
 718                         break;
 719         }
 720         return (ret);
 721 }