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/libkern.h>
  38 #include <sys/limits.h>
  39 #include <sys/lock.h>
  40 #include <sys/malloc.h>
  41 #include <sys/mutex.h>
  42 #include <sys/proc.h>
  43 #include <sys/sched.h>
  44 #include <sys/smp.h>
  45 #include <sys/taskqueue.h>
  46 #include <sys/unistd.h>
  47 #include <machine/stdarg.h>
  48
  49 static MALLOC_DEFINE(M_TASKQUEUE, "taskqueue", "Task Queues");
  50 static void     *taskqueue_giant_ih;
  51 static void     *taskqueue_ih;
  52 static void      taskqueue_fast_enqueue(void *);
  53 static void      taskqueue_swi_enqueue(void *);
  54 static void      taskqueue_swi_giant_enqueue(void *);
  55
  56 struct taskqueue_busy {
  57         struct task     *tb_running;
  58         TAILQ_ENTRY(taskqueue_busy) tb_link;
  59 };
  60
  61 struct task * const TB_DRAIN_WAITER = (struct task *)0x1;
  62
  63 struct taskqueue {
  64         STAILQ_HEAD(, task)     tq_queue;
  65         taskqueue_enqueue_fn    tq_enqueue;
  66         void                    *tq_context;
  67         char                    *tq_name;
  68         TAILQ_HEAD(, taskqueue_busy) tq_active;
  69         struct mtx              tq_mutex;
  70         struct thread           **tq_threads;
  71         int                     tq_tcount;
  72         int                     tq_spin;
  73         int                     tq_flags;
  74         int                     tq_callouts;
  75         taskqueue_callback_fn   tq_callbacks[TASKQUEUE_NUM_CALLBACKS];
  76         void                    *tq_cb_contexts[TASKQUEUE_NUM_CALLBACKS];
  77 };
  78
  79 #define TQ_FLAGS_ACTIVE         (1 << 0)
  80 #define TQ_FLAGS_BLOCKED        (1 << 1)
  81 #define TQ_FLAGS_UNLOCKED_ENQUEUE       (1 << 2)
  82
  83 #define DT_CALLOUT_ARMED        (1 << 0)
  84 #define DT_DRAIN_IN_PROGRESS    (1 << 1)
  85
  86 #define TQ_LOCK(tq)                                                     \
  87         do {                                                            \
  88                 if ((tq)->tq_spin)                                      \
  89                         mtx_lock_spin(&(tq)->tq_mutex);                 \
  90                 else                                                    \
  91                         mtx_lock(&(tq)->tq_mutex);                      \
  92         } while (0)
  93 #define TQ_ASSERT_LOCKED(tq)    mtx_assert(&(tq)->tq_mutex, MA_OWNED)
  94
  95 #define TQ_UNLOCK(tq)                                                   \
  96         do {                                                            \
  97                 if ((tq)->tq_spin)                                      \
  98                         mtx_unlock_spin(&(tq)->tq_mutex);               \
  99                 else                                                    \
 100                         mtx_unlock(&(tq)->tq_mutex);                    \
 101         } while (0)
 102 #define TQ_ASSERT_UNLOCKED(tq)  mtx_assert(&(tq)->tq_mutex, MA_NOTOWNED)
 103
 104 void
 105 _timeout_task_init(struct taskqueue *queue, struct timeout_task *timeout_task,
 106     int priority, task_fn_t func, void *context)
 107 {
 108
 109         TASK_INIT(&timeout_task->t, priority, func, context);
 110         callout_init_mtx(&timeout_task->c, &queue->tq_mutex,
 111             CALLOUT_RETURNUNLOCKED);
 112         timeout_task->q = queue;
 113         timeout_task->f = 0;
 114 }
 115
 116 static __inline int
 117 TQ_SLEEP(struct taskqueue *tq, void *p, struct mtx *m, int pri, const char *wm,
 118     int t)
 119 {
 120         if (tq->tq_spin)
 121                 return (msleep_spin(p, m, wm, t));
 122         return (msleep(p, m, pri, wm, t));
 123 }
 124
 125 static struct taskqueue *
 126 _taskqueue_create(const char *name, int mflags,
 127                  taskqueue_enqueue_fn enqueue, void *context,
 128                  int mtxflags, const char *mtxname __unused)
 129 {
 130         struct taskqueue *queue;
 131         char *tq_name;
 132
 133         tq_name = malloc(TASKQUEUE_NAMELEN, M_TASKQUEUE, mflags | M_ZERO);
 134         if (tq_name == NULL)
 135                 return (NULL);
 136
 137         queue = malloc(sizeof(struct taskqueue), M_TASKQUEUE, mflags | M_ZERO);
 138         if (queue == NULL) {
 139                 free(tq_name, M_TASKQUEUE);
 140                 return (NULL);
 141         }
 142
 143         snprintf(tq_name, TASKQUEUE_NAMELEN, "%s", (name) ? name : "taskqueue");
 144
 145         STAILQ_INIT(&queue->tq_queue);
 146         TAILQ_INIT(&queue->tq_active);
 147         queue->tq_enqueue = enqueue;
 148         queue->tq_context = context;
 149         queue->tq_name = tq_name;
 150         queue->tq_spin = (mtxflags & MTX_SPIN) != 0;
 151         queue->tq_flags |= TQ_FLAGS_ACTIVE;
 152         if (enqueue == taskqueue_fast_enqueue ||
 153             enqueue == taskqueue_swi_enqueue ||
 154             enqueue == taskqueue_swi_giant_enqueue ||
 155             enqueue == taskqueue_thread_enqueue)
 156                 queue->tq_flags |= TQ_FLAGS_UNLOCKED_ENQUEUE;
 157         mtx_init(&queue->tq_mutex, tq_name, NULL, mtxflags);
 158
 159         return (queue);
 160 }
 161
 162 struct taskqueue *
 163 taskqueue_create(const char *name, int mflags,
 164                  taskqueue_enqueue_fn enqueue, void *context)
 165 {
 166
 167         return _taskqueue_create(name, mflags, enqueue, context,
 168                         MTX_DEF, name);
 169 }
 170
 171 void
 172 taskqueue_set_callback(struct taskqueue *queue,
 173     enum taskqueue_callback_type cb_type, taskqueue_callback_fn callback,
 174     void *context)
 175 {
 176
 177         KASSERT(((cb_type >= TASKQUEUE_CALLBACK_TYPE_MIN) &&
 178             (cb_type <= TASKQUEUE_CALLBACK_TYPE_MAX)),
 179             ("Callback type %d not valid, must be %d-%d", cb_type,
 180             TASKQUEUE_CALLBACK_TYPE_MIN, TASKQUEUE_CALLBACK_TYPE_MAX));
 181         KASSERT((queue->tq_callbacks[cb_type] == NULL),
 182             ("Re-initialization of taskqueue callback?"));
 183
 184         queue->tq_callbacks[cb_type] = callback;
 185         queue->tq_cb_contexts[cb_type] = context;
 186 }
 187
 188 /*
 189  * Signal a taskqueue thread to terminate.
 190  */
 191 static void
 192 taskqueue_terminate(struct thread **pp, struct taskqueue *tq)
 193 {
 194
 195         while (tq->tq_tcount > 0 || tq->tq_callouts > 0) {
 196                 wakeup(tq);
 197                 TQ_SLEEP(tq, pp, &tq->tq_mutex, PWAIT, "taskqueue_destroy", 0);
 198         }
 199 }
 200
 201 void
 202 taskqueue_free(struct taskqueue *queue)
 203 {
 204
 205         TQ_LOCK(queue);
 206         queue->tq_flags &= ~TQ_FLAGS_ACTIVE;
 207         taskqueue_terminate(queue->tq_threads, queue);
 208         KASSERT(TAILQ_EMPTY(&queue->tq_active), ("Tasks still running?"));
 209         KASSERT(queue->tq_callouts == 0, ("Armed timeout tasks"));
 210         mtx_destroy(&queue->tq_mutex);
 211         free(queue->tq_threads, M_TASKQUEUE);
 212         free(queue->tq_name, M_TASKQUEUE);
 213         free(queue, M_TASKQUEUE);
 214 }
 215
 216 static int
 217 taskqueue_enqueue_locked(struct taskqueue *queue, struct task *task)
 218 {
 219         struct task *ins;
 220         struct task *prev;
 221
 222         KASSERT(task->ta_func != NULL, ("enqueueing task with NULL func"));
 223         /*
 224          * Count multiple enqueues.
 225          */
 226         if (task->ta_pending) {
 227                 if (task->ta_pending < USHRT_MAX)
 228                         task->ta_pending++;
 229                 TQ_UNLOCK(queue);
 230                 return (0);
 231         }
 232
 233         /*
 234          * Optimise the case when all tasks have the same priority.
 235          */
 236         prev = STAILQ_LAST(&queue->tq_queue, task, ta_link);
 237         if (!prev || prev->ta_priority >= task->ta_priority) {
 238                 STAILQ_INSERT_TAIL(&queue->tq_queue, task, ta_link);
 239         } else {
 240                 prev = NULL;
 241                 for (ins = STAILQ_FIRST(&queue->tq_queue); ins;
 242                      prev = ins, ins = STAILQ_NEXT(ins, ta_link))
 243                         if (ins->ta_priority < task->ta_priority)
 244                                 break;
 245
 246                 if (prev)
 247                         STAILQ_INSERT_AFTER(&queue->tq_queue, prev, task, ta_link);
 248                 else
 249                         STAILQ_INSERT_HEAD(&queue->tq_queue, task, ta_link);
 250         }
 251
 252         task->ta_pending = 1;
 253         if ((queue->tq_flags & TQ_FLAGS_UNLOCKED_ENQUEUE) != 0)
 254                 TQ_UNLOCK(queue);
 255         if ((queue->tq_flags & TQ_FLAGS_BLOCKED) == 0)
 256                 queue->tq_enqueue(queue->tq_context);
 257         if ((queue->tq_flags & TQ_FLAGS_UNLOCKED_ENQUEUE) == 0)
 258                 TQ_UNLOCK(queue);
 259
 260         /* Return with lock released. */
 261         return (0);
 262 }
 263
 264 int
 265 taskqueue_enqueue(struct taskqueue *queue, struct task *task)
 266 {
 267         int res;
 268
 269         TQ_LOCK(queue);
 270         res = taskqueue_enqueue_locked(queue, task);
 271         /* The lock is released inside. */
 272
 273         return (res);
 274 }
 275
 276 static void
 277 taskqueue_timeout_func(void *arg)
 278 {
 279         struct taskqueue *queue;
 280         struct timeout_task *timeout_task;
 281
 282         timeout_task = arg;
 283         queue = timeout_task->q;
 284         KASSERT((timeout_task->f & DT_CALLOUT_ARMED) != 0, ("Stray timeout"));
 285         timeout_task->f &= ~DT_CALLOUT_ARMED;
 286         queue->tq_callouts--;
 287         taskqueue_enqueue_locked(timeout_task->q, &timeout_task->t);
 288         /* The lock is released inside. */
 289 }
 290
 291 int
 292 taskqueue_enqueue_timeout_sbt(struct taskqueue *queue,
 293     struct timeout_task *timeout_task, sbintime_t sbt, sbintime_t pr, int flags)
 294 {
 295         int res;
 296
 297         TQ_LOCK(queue);
 298         KASSERT(timeout_task->q == NULL || timeout_task->q == queue,
 299             ("Migrated queue"));
 300         KASSERT(!queue->tq_spin, ("Timeout for spin-queue"));
 301         timeout_task->q = queue;
 302         res = timeout_task->t.ta_pending;
 303         if (timeout_task->f & DT_DRAIN_IN_PROGRESS) {
 304                 /* Do nothing */
 305                 TQ_UNLOCK(queue);
 306                 res = -1;
 307         } else if (sbt == 0) {
 308                 taskqueue_enqueue_locked(queue, &timeout_task->t);
 309                 /* The lock is released inside. */
 310         } else {
 311                 if ((timeout_task->f & DT_CALLOUT_ARMED) != 0) {
 312                         res++;
 313                 } else {
 314                         queue->tq_callouts++;
 315                         timeout_task->f |= DT_CALLOUT_ARMED;
 316                         if (sbt < 0)
 317                                 sbt = -sbt; /* Ignore overflow. */
 318                 }
 319                 if (sbt > 0) {
 320                         callout_reset_sbt(&timeout_task->c, sbt, pr,
 321                             taskqueue_timeout_func, timeout_task, flags);
 322                 }
 323                 TQ_UNLOCK(queue);
 324         }
 325         return (res);
 326 }
 327
 328 int
 329 taskqueue_enqueue_timeout(struct taskqueue *queue,
 330     struct timeout_task *ttask, int ticks)
 331 {
 332
 333         return (taskqueue_enqueue_timeout_sbt(queue, ttask, ticks * tick_sbt,
 334             0, 0));
 335 }
 336
 337 static void
 338 taskqueue_task_nop_fn(void *context, int pending)
 339 {
 340 }
 341
 342 /*
 343  * Block until all currently queued tasks in this taskqueue
 344  * have begun execution.  Tasks queued during execution of
 345  * this function are ignored.
 346  */
 347 static int
 348 taskqueue_drain_tq_queue(struct taskqueue *queue)
 349 {
 350         struct task t_barrier;
 351
 352         if (STAILQ_EMPTY(&queue->tq_queue))
 353                 return (0);
 354
 355         /*
 356          * Enqueue our barrier after all current tasks, but with
 357          * the highest priority so that newly queued tasks cannot
 358          * pass it.  Because of the high priority, we can not use
 359          * taskqueue_enqueue_locked directly (which drops the lock
 360          * anyway) so just insert it at tail while we have the
 361          * queue lock.
 362          */
 363         TASK_INIT(&t_barrier, USHRT_MAX, taskqueue_task_nop_fn, &t_barrier);
 364         STAILQ_INSERT_TAIL(&queue->tq_queue, &t_barrier, ta_link);
 365         t_barrier.ta_pending = 1;
 366
 367         /*
 368          * Once the barrier has executed, all previously queued tasks
 369          * have completed or are currently executing.
 370          */
 371         while (t_barrier.ta_pending != 0)
 372                 TQ_SLEEP(queue, &t_barrier, &queue->tq_mutex, PWAIT, "-", 0);
 373         return (1);
 374 }
 375
 376 /*
 377  * Block until all currently executing tasks for this taskqueue
 378  * complete.  Tasks that begin execution during the execution
 379  * of this function are ignored.
 380  */
 381 static int
 382 taskqueue_drain_tq_active(struct taskqueue *queue)
 383 {
 384         struct taskqueue_busy tb_marker, *tb_first;
 385
 386         if (TAILQ_EMPTY(&queue->tq_active))
 387                 return (0);
 388
 389         /* Block taskq_terminate().*/
 390         queue->tq_callouts++;
 391
 392         /*
 393          * Wait for all currently executing taskqueue threads
 394          * to go idle.
 395          */
 396         tb_marker.tb_running = TB_DRAIN_WAITER;
 397         TAILQ_INSERT_TAIL(&queue->tq_active, &tb_marker, tb_link);
 398         while (TAILQ_FIRST(&queue->tq_active) != &tb_marker)
 399                 TQ_SLEEP(queue, &tb_marker, &queue->tq_mutex, PWAIT, "-", 0);
 400         TAILQ_REMOVE(&queue->tq_active, &tb_marker, tb_link);
 401
 402         /*
 403          * Wakeup any other drain waiter that happened to queue up
 404          * without any intervening active thread.
 405          */
 406         tb_first = TAILQ_FIRST(&queue->tq_active);
 407         if (tb_first != NULL && tb_first->tb_running == TB_DRAIN_WAITER)
 408                 wakeup(tb_first);
 409
 410         /* Release taskqueue_terminate(). */
 411         queue->tq_callouts--;
 412         if ((queue->tq_flags & TQ_FLAGS_ACTIVE) == 0)
 413                 wakeup_one(queue->tq_threads);
 414         return (1);
 415 }
 416
 417 void
 418 taskqueue_block(struct taskqueue *queue)
 419 {
 420
 421         TQ_LOCK(queue);
 422         queue->tq_flags |= TQ_FLAGS_BLOCKED;
 423         TQ_UNLOCK(queue);
 424 }
 425
 426 void
 427 taskqueue_unblock(struct taskqueue *queue)
 428 {
 429
 430         TQ_LOCK(queue);
 431         queue->tq_flags &= ~TQ_FLAGS_BLOCKED;
 432         if (!STAILQ_EMPTY(&queue->tq_queue))
 433                 queue->tq_enqueue(queue->tq_context);
 434         TQ_UNLOCK(queue);
 435 }
 436
 437 static void
 438 taskqueue_run_locked(struct taskqueue *queue)
 439 {
 440         struct taskqueue_busy tb;
 441         struct taskqueue_busy *tb_first;
 442         struct task *task;
 443         int pending;
 444
 445         KASSERT(queue != NULL, ("tq is NULL"));
 446         TQ_ASSERT_LOCKED(queue);
 447         tb.tb_running = NULL;
 448
 449         while (STAILQ_FIRST(&queue->tq_queue)) {
 450                 TAILQ_INSERT_TAIL(&queue->tq_active, &tb, tb_link);
 451
 452                 /*
 453                  * Carefully remove the first task from the queue and
 454                  * zero its pending count.
 455                  */
 456                 task = STAILQ_FIRST(&queue->tq_queue);
 457                 KASSERT(task != NULL, ("task is NULL"));
 458                 STAILQ_REMOVE_HEAD(&queue->tq_queue, ta_link);
 459                 pending = task->ta_pending;
 460                 task->ta_pending = 0;
 461                 tb.tb_running = task;
 462                 TQ_UNLOCK(queue);
 463
 464                 KASSERT(task->ta_func != NULL, ("task->ta_func is NULL"));
 465                 task->ta_func(task->ta_context, pending);
 466
 467                 TQ_LOCK(queue);
 468                 tb.tb_running = NULL;
 469                 wakeup(task);
 470
 471                 TAILQ_REMOVE(&queue->tq_active, &tb, tb_link);
 472                 tb_first = TAILQ_FIRST(&queue->tq_active);
 473                 if (tb_first != NULL &&
 474                     tb_first->tb_running == TB_DRAIN_WAITER)
 475                         wakeup(tb_first);
 476         }
 477 }
 478
 479 void
 480 taskqueue_run(struct taskqueue *queue)
 481 {
 482
 483         TQ_LOCK(queue);
 484         taskqueue_run_locked(queue);
 485         TQ_UNLOCK(queue);
 486 }
 487
 488 static int
 489 task_is_running(struct taskqueue *queue, struct task *task)
 490 {
 491         struct taskqueue_busy *tb;
 492
 493         TQ_ASSERT_LOCKED(queue);
 494         TAILQ_FOREACH(tb, &queue->tq_active, tb_link) {
 495                 if (tb->tb_running == task)
 496                         return (1);
 497         }
 498         return (0);
 499 }
 500
 501 /*
 502  * Only use this function in single threaded contexts. It returns
 503  * non-zero if the given task is either pending or running. Else the
 504  * task is idle and can be queued again or freed.
 505  */
 506 int
 507 taskqueue_poll_is_busy(struct taskqueue *queue, struct task *task)
 508 {
 509         int retval;
 510
 511         TQ_LOCK(queue);
 512         retval = task->ta_pending > 0 || task_is_running(queue, task);
 513         TQ_UNLOCK(queue);
 514
 515         return (retval);
 516 }
 517
 518 static int
 519 taskqueue_cancel_locked(struct taskqueue *queue, struct task *task,
 520     u_int *pendp)
 521 {
 522
 523         if (task->ta_pending > 0)
 524                 STAILQ_REMOVE(&queue->tq_queue, task, task, ta_link);
 525         if (pendp != NULL)
 526                 *pendp = task->ta_pending;
 527         task->ta_pending = 0;
 528         return (task_is_running(queue, task) ? EBUSY : 0);
 529 }
 530
 531 int
 532 taskqueue_cancel(struct taskqueue *queue, struct task *task, u_int *pendp)
 533 {
 534         int error;
 535
 536         TQ_LOCK(queue);
 537         error = taskqueue_cancel_locked(queue, task, pendp);
 538         TQ_UNLOCK(queue);
 539
 540         return (error);
 541 }
 542
 543 int
 544 taskqueue_cancel_timeout(struct taskqueue *queue,
 545     struct timeout_task *timeout_task, u_int *pendp)
 546 {
 547         u_int pending, pending1;
 548         int error;
 549
 550         TQ_LOCK(queue);
 551         pending = !!(callout_stop(&timeout_task->c) > 0);
 552         error = taskqueue_cancel_locked(queue, &timeout_task->t, &pending1);
 553         if ((timeout_task->f & DT_CALLOUT_ARMED) != 0) {
 554                 timeout_task->f &= ~DT_CALLOUT_ARMED;
 555                 queue->tq_callouts--;
 556         }
 557         TQ_UNLOCK(queue);
 558
 559         if (pendp != NULL)
 560                 *pendp = pending + pending1;
 561         return (error);
 562 }
 563
 564 void
 565 taskqueue_drain(struct taskqueue *queue, struct task *task)
 566 {
 567
 568         if (!queue->tq_spin)
 569                 WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, NULL, __func__);
 570
 571         TQ_LOCK(queue);
 572         while (task->ta_pending != 0 || task_is_running(queue, task))
 573                 TQ_SLEEP(queue, task, &queue->tq_mutex, PWAIT, "-", 0);
 574         TQ_UNLOCK(queue);
 575 }
 576
 577 void
 578 taskqueue_drain_all(struct taskqueue *queue)
 579 {
 580
 581         if (!queue->tq_spin)
 582                 WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, NULL, __func__);
 583
 584         TQ_LOCK(queue);
 585         (void)taskqueue_drain_tq_queue(queue);
 586         (void)taskqueue_drain_tq_active(queue);
 587         TQ_UNLOCK(queue);
 588 }
 589
 590 void
 591 taskqueue_drain_timeout(struct taskqueue *queue,
 592     struct timeout_task *timeout_task)
 593 {
 594
 595         /*
 596          * Set flag to prevent timer from re-starting during drain:
 597          */
 598         TQ_LOCK(queue);
 599         KASSERT((timeout_task->f & DT_DRAIN_IN_PROGRESS) == 0,
 600             ("Drain already in progress"));
 601         timeout_task->f |= DT_DRAIN_IN_PROGRESS;
 602         TQ_UNLOCK(queue);
 603
 604         callout_drain(&timeout_task->c);
 605         taskqueue_drain(queue, &timeout_task->t);
 606
 607         /*
 608          * Clear flag to allow timer to re-start:
 609          */
 610         TQ_LOCK(queue);
 611         timeout_task->f &= ~DT_DRAIN_IN_PROGRESS;
 612         TQ_UNLOCK(queue);
 613 }
 614
 615 void
 616 taskqueue_quiesce(struct taskqueue *queue)
 617 {
 618         int ret;
 619
 620         TQ_LOCK(queue);
 621         do {
 622                 ret = taskqueue_drain_tq_queue(queue);
 623                 if (ret == 0)
 624                         ret = taskqueue_drain_tq_active(queue);
 625         } while (ret != 0);
 626         TQ_UNLOCK(queue);
 627 }
 628
 629 static void
 630 taskqueue_swi_enqueue(void *context)
 631 {
 632         swi_sched(taskqueue_ih, 0);
 633 }
 634
 635 static void
 636 taskqueue_swi_run(void *dummy)
 637 {
 638         taskqueue_run(taskqueue_swi);
 639 }
 640
 641 static void
 642 taskqueue_swi_giant_enqueue(void *context)
 643 {
 644         swi_sched(taskqueue_giant_ih, 0);
 645 }
 646
 647 static void
 648 taskqueue_swi_giant_run(void *dummy)
 649 {
 650         taskqueue_run(taskqueue_swi_giant);
 651 }
 652
 653 static int
 654 _taskqueue_start_threads(struct taskqueue **tqp, int count, int pri,
 655     cpuset_t *mask, const char *name, va_list ap)
 656 {
 657         char ktname[MAXCOMLEN + 1];
 658         struct thread *td;
 659         struct taskqueue *tq;
 660         int i, error;
 661
 662         if (count <= 0)
 663                 return (EINVAL);
 664
 665         vsnprintf(ktname, sizeof(ktname), name, ap);
 666         tq = *tqp;
 667
 668         tq->tq_threads = malloc(sizeof(struct thread *) * count, M_TASKQUEUE,
 669             M_NOWAIT | M_ZERO);
 670         if (tq->tq_threads == NULL) {
 671                 printf("%s: no memory for %s threads\n", __func__, ktname);
 672                 return (ENOMEM);
 673         }
 674
 675         for (i = 0; i < count; i++) {
 676                 if (count == 1)
 677                         error = kthread_add(taskqueue_thread_loop, tqp, NULL,
 678                             &tq->tq_threads[i], RFSTOPPED, 0, "%s", ktname);
 679                 else
 680                         error = kthread_add(taskqueue_thread_loop, tqp, NULL,
 681                             &tq->tq_threads[i], RFSTOPPED, 0,
 682                             "%s_%d", ktname, i);
 683                 if (error) {
 684                         /* should be ok to continue, taskqueue_free will dtrt */
 685                         printf("%s: kthread_add(%s): error %d", __func__,
 686                             ktname, error);
 687                         tq->tq_threads[i] = NULL;               /* paranoid */
 688                 } else
 689                         tq->tq_tcount++;
 690         }
 691         if (tq->tq_tcount == 0) {
 692                 free(tq->tq_threads, M_TASKQUEUE);
 693                 tq->tq_threads = NULL;
 694                 return (ENOMEM);
 695         }
 696         for (i = 0; i < count; i++) {
 697                 if (tq->tq_threads[i] == NULL)
 698                         continue;
 699                 td = tq->tq_threads[i];
 700                 if (mask) {
 701                         error = cpuset_setthread(td->td_tid, mask);
 702                         /*
 703                          * Failing to pin is rarely an actual fatal error;
 704                          * it'll just affect performance.
 705                          */
 706                         if (error)
 707                                 printf("%s: curthread=%llu: can't pin; "
 708                                     "error=%d\n",
 709                                     __func__,
 710                                     (unsigned long long) td->td_tid,
 711                                     error);
 712                 }
 713                 thread_lock(td);
 714                 sched_prio(td, pri);
 715                 sched_add(td, SRQ_BORING);
 716                 thread_unlock(td);
 717         }
 718
 719         return (0);
 720 }
 721
 722 int
 723 taskqueue_start_threads(struct taskqueue **tqp, int count, int pri,
 724     const char *name, ...)
 725 {
 726         va_list ap;
 727         int error;
 728
 729         va_start(ap, name);
 730         error = _taskqueue_start_threads(tqp, count, pri, NULL, name, ap);
 731         va_end(ap);
 732         return (error);
 733 }
 734
 735 int
 736 taskqueue_start_threads_cpuset(struct taskqueue **tqp, int count, int pri,
 737     cpuset_t *mask, const char *name, ...)
 738 {
 739         va_list ap;
 740         int error;
 741
 742         va_start(ap, name);
 743         error = _taskqueue_start_threads(tqp, count, pri, mask, name, ap);
 744         va_end(ap);
 745         return (error);
 746 }
 747
 748 static inline void
 749 taskqueue_run_callback(struct taskqueue *tq,
 750     enum taskqueue_callback_type cb_type)
 751 {
 752         taskqueue_callback_fn tq_callback;
 753
 754         TQ_ASSERT_UNLOCKED(tq);
 755         tq_callback = tq->tq_callbacks[cb_type];
 756         if (tq_callback != NULL)
 757                 tq_callback(tq->tq_cb_contexts[cb_type]);
 758 }
 759
 760 void
 761 taskqueue_thread_loop(void *arg)
 762 {
 763         struct taskqueue **tqp, *tq;
 764
 765         tqp = arg;
 766         tq = *tqp;
 767         taskqueue_run_callback(tq, TASKQUEUE_CALLBACK_TYPE_INIT);
 768         TQ_LOCK(tq);
 769         while ((tq->tq_flags & TQ_FLAGS_ACTIVE) != 0) {
 770                 /* XXX ? */
 771                 taskqueue_run_locked(tq);
 772                 /*
 773                  * Because taskqueue_run() can drop tq_mutex, we need to
 774                  * check if the TQ_FLAGS_ACTIVE flag wasn't removed in the
 775                  * meantime, which means we missed a wakeup.
 776                  */
 777                 if ((tq->tq_flags & TQ_FLAGS_ACTIVE) == 0)
 778                         break;
 779                 TQ_SLEEP(tq, tq, &tq->tq_mutex, 0, "-", 0);
 780         }
 781         taskqueue_run_locked(tq);
 782         /*
 783          * This thread is on its way out, so just drop the lock temporarily
 784          * in order to call the shutdown callback.  This allows the callback
 785          * to look at the taskqueue, even just before it dies.
 786          */
 787         TQ_UNLOCK(tq);
 788         taskqueue_run_callback(tq, TASKQUEUE_CALLBACK_TYPE_SHUTDOWN);
 789         TQ_LOCK(tq);
 790
 791         /* rendezvous with thread that asked us to terminate */
 792         tq->tq_tcount--;
 793         wakeup_one(tq->tq_threads);
 794         TQ_UNLOCK(tq);
 795         kthread_exit();
 796 }
 797
 798 void
 799 taskqueue_thread_enqueue(void *context)
 800 {
 801         struct taskqueue **tqp, *tq;
 802
 803         tqp = context;
 804         tq = *tqp;
 805         wakeup_one(tq);
 806 }
 807
 808 TASKQUEUE_DEFINE(swi, taskqueue_swi_enqueue, NULL,
 809                  swi_add(NULL, "task queue", taskqueue_swi_run, NULL, SWI_TQ,
 810                      INTR_MPSAFE, &taskqueue_ih));
 811
 812 TASKQUEUE_DEFINE(swi_giant, taskqueue_swi_giant_enqueue, NULL,
 813                  swi_add(NULL, "Giant taskq", taskqueue_swi_giant_run,
 814                      NULL, SWI_TQ_GIANT, 0, &taskqueue_giant_ih));
 815
 816 TASKQUEUE_DEFINE_THREAD(thread);
 817
 818 struct taskqueue *
 819 taskqueue_create_fast(const char *name, int mflags,
 820                  taskqueue_enqueue_fn enqueue, void *context)
 821 {
 822         return _taskqueue_create(name, mflags, enqueue, context,
 823                         MTX_SPIN, "fast_taskqueue");
 824 }
 825
 826 static void     *taskqueue_fast_ih;
 827
 828 static void
 829 taskqueue_fast_enqueue(void *context)
 830 {
 831         swi_sched(taskqueue_fast_ih, 0);
 832 }
 833
 834 static void
 835 taskqueue_fast_run(void *dummy)
 836 {
 837         taskqueue_run(taskqueue_fast);
 838 }
 839
 840 TASKQUEUE_FAST_DEFINE(fast, taskqueue_fast_enqueue, NULL,
 841         swi_add(NULL, "fast taskq", taskqueue_fast_run, NULL,
 842         SWI_TQ_FAST, INTR_MPSAFE, &taskqueue_fast_ih));
 843
 844 int
 845 taskqueue_member(struct taskqueue *queue, struct thread *td)
 846 {
 847         int i, j, ret = 0;
 848
 849         for (i = 0, j = 0; ; i++) {
 850                 if (queue->tq_threads[i] == NULL)
 851                         continue;
 852                 if (queue->tq_threads[i] == td) {
 853                         ret = 1;
 854                         break;
 855                 }
 856                 if (++j >= queue->tq_tcount)
 857                         break;
 858         }
 859         return (ret);
 860 }