sys/kern/subr_taskqueue.c

   1 /*-
   2  * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
   3  *
   4  * Copyright (c) 2000 Doug Rabson
   5  * All rights reserved.
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, this list of conditions and the following disclaimer.
  12  * 2. Redistributions in binary form must reproduce the above copyright
  13  *    notice, this list of conditions and the following disclaimer in the
  14  *    documentation and/or other materials provided with the distribution.
  15  *
  16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  17  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  18  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  19  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  20  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  21  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  22  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  23  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  24  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  25  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  26  * SUCH DAMAGE.
  27  */
  28
  29 #include <sys/cdefs.h>
  30 __FBSDID("$FreeBSD$");
  31
  32 #include <sys/param.h>
  33 #include <sys/systm.h>
  34 #include <sys/bus.h>
  35 #include <sys/cpuset.h>
  36 #include <sys/interrupt.h>
  37 #include <sys/kernel.h>
  38 #include <sys/kthread.h>
  39 #include <sys/libkern.h>
  40 #include <sys/limits.h>
  41 #include <sys/lock.h>
  42 #include <sys/malloc.h>
  43 #include <sys/mutex.h>
  44 #include <sys/proc.h>
  45 #include <sys/epoch.h>
  46 #include <sys/sched.h>
  47 #include <sys/smp.h>
  48 #include <sys/taskqueue.h>
  49 #include <sys/unistd.h>
  50 #include <machine/stdarg.h>
  51
  52 static MALLOC_DEFINE(M_TASKQUEUE, "taskqueue", "Task Queues");
  53 static void     *taskqueue_giant_ih;
  54 static void     *taskqueue_ih;
  55 static void      taskqueue_fast_enqueue(void *);
  56 static void      taskqueue_swi_enqueue(void *);
  57 static void      taskqueue_swi_giant_enqueue(void *);
  58
  59 struct taskqueue_busy {
  60         struct task             *tb_running;
  61         u_int                    tb_seq;
  62         LIST_ENTRY(taskqueue_busy) tb_link;
  63 };
  64
  65 struct taskqueue {
  66         STAILQ_HEAD(, task)     tq_queue;
  67         LIST_HEAD(, taskqueue_busy) tq_active;
  68         struct task             *tq_hint;
  69         u_int                   tq_seq;
  70         int                     tq_callouts;
  71         struct mtx_padalign     tq_mutex;
  72         taskqueue_enqueue_fn    tq_enqueue;
  73         void                    *tq_context;
  74         char                    *tq_name;
  75         struct thread           **tq_threads;
  76         int                     tq_tcount;
  77         int                     tq_spin;
  78         int                     tq_flags;
  79         taskqueue_callback_fn   tq_callbacks[TASKQUEUE_NUM_CALLBACKS];
  80         void                    *tq_cb_contexts[TASKQUEUE_NUM_CALLBACKS];
  81 };
  82
  83 #define TQ_FLAGS_ACTIVE         (1 << 0)
  84 #define TQ_FLAGS_BLOCKED        (1 << 1)
  85 #define TQ_FLAGS_UNLOCKED_ENQUEUE       (1 << 2)
  86
  87 #define DT_CALLOUT_ARMED        (1 << 0)
  88 #define DT_DRAIN_IN_PROGRESS    (1 << 1)
  89
  90 #define TQ_LOCK(tq)                                                     \
  91         do {                                                            \
  92                 if ((tq)->tq_spin)                                      \
  93                         mtx_lock_spin(&(tq)->tq_mutex);                 \
  94                 else                                                    \
  95                         mtx_lock(&(tq)->tq_mutex);                      \
  96         } while (0)
  97 #define TQ_ASSERT_LOCKED(tq)    mtx_assert(&(tq)->tq_mutex, MA_OWNED)
  98
  99 #define TQ_UNLOCK(tq)                                                   \
 100         do {                                                            \
 101                 if ((tq)->tq_spin)                                      \
 102                         mtx_unlock_spin(&(tq)->tq_mutex);               \
 103                 else                                                    \
 104                         mtx_unlock(&(tq)->tq_mutex);                    \
 105         } while (0)
 106 #define TQ_ASSERT_UNLOCKED(tq)  mtx_assert(&(tq)->tq_mutex, MA_NOTOWNED)
 107
 108 void
 109 _timeout_task_init(struct taskqueue *queue, struct timeout_task *timeout_task,
 110     int priority, task_fn_t func, void *context)
 111 {
 112
 113         TASK_INIT(&timeout_task->t, priority, func, context);
 114         callout_init_mtx(&timeout_task->c, &queue->tq_mutex,
 115             CALLOUT_RETURNUNLOCKED);
 116         timeout_task->q = queue;
 117         timeout_task->f = 0;
 118 }
 119
 120 static __inline int
 121 TQ_SLEEP(struct taskqueue *tq, void *p, const char *wm)
 122 {
 123         if (tq->tq_spin)
 124                 return (msleep_spin(p, (struct mtx *)&tq->tq_mutex, wm, 0));
 125         return (msleep(p, &tq->tq_mutex, 0, wm, 0));
 126 }
 127
 128 static struct taskqueue *
 129 _taskqueue_create(const char *name, int mflags,
 130                  taskqueue_enqueue_fn enqueue, void *context,
 131                  int mtxflags, const char *mtxname __unused)
 132 {
 133         struct taskqueue *queue;
 134         char *tq_name;
 135
 136         tq_name = malloc(TASKQUEUE_NAMELEN, M_TASKQUEUE, mflags | M_ZERO);
 137         if (tq_name == NULL)
 138                 return (NULL);
 139
 140         queue = malloc(sizeof(struct taskqueue), M_TASKQUEUE, mflags | M_ZERO);
 141         if (queue == NULL) {
 142                 free(tq_name, M_TASKQUEUE);
 143                 return (NULL);
 144         }
 145
 146         snprintf(tq_name, TASKQUEUE_NAMELEN, "%s", (name) ? name : "taskqueue");
 147
 148         STAILQ_INIT(&queue->tq_queue);
 149         LIST_INIT(&queue->tq_active);
 150         queue->tq_enqueue = enqueue;
 151         queue->tq_context = context;
 152         queue->tq_name = tq_name;
 153         queue->tq_spin = (mtxflags & MTX_SPIN) != 0;
 154         queue->tq_flags |= TQ_FLAGS_ACTIVE;
 155         if (enqueue == taskqueue_fast_enqueue ||
 156             enqueue == taskqueue_swi_enqueue ||
 157             enqueue == taskqueue_swi_giant_enqueue ||
 158             enqueue == taskqueue_thread_enqueue)
 159                 queue->tq_flags |= TQ_FLAGS_UNLOCKED_ENQUEUE;
 160         mtx_init(&queue->tq_mutex, tq_name, NULL, mtxflags);
 161
 162         return (queue);
 163 }
 164
 165 struct taskqueue *
 166 taskqueue_create(const char *name, int mflags,
 167                  taskqueue_enqueue_fn enqueue, void *context)
 168 {
 169
 170         return _taskqueue_create(name, mflags, enqueue, context,
 171                         MTX_DEF, name);
 172 }
 173
 174 void
 175 taskqueue_set_callback(struct taskqueue *queue,
 176     enum taskqueue_callback_type cb_type, taskqueue_callback_fn callback,
 177     void *context)
 178 {
 179
 180         KASSERT(((cb_type >= TASKQUEUE_CALLBACK_TYPE_MIN) &&
 181             (cb_type <= TASKQUEUE_CALLBACK_TYPE_MAX)),
 182             ("Callback type %d not valid, must be %d-%d", cb_type,
 183             TASKQUEUE_CALLBACK_TYPE_MIN, TASKQUEUE_CALLBACK_TYPE_MAX));
 184         KASSERT((queue->tq_callbacks[cb_type] == NULL),
 185             ("Re-initialization of taskqueue callback?"));
 186
 187         queue->tq_callbacks[cb_type] = callback;
 188         queue->tq_cb_contexts[cb_type] = context;
 189 }
 190
 191 /*
 192  * Signal a taskqueue thread to terminate.
 193  */
 194 static void
 195 taskqueue_terminate(struct thread **pp, struct taskqueue *tq)
 196 {
 197
 198         while (tq->tq_tcount > 0 || tq->tq_callouts > 0) {
 199                 wakeup(tq);
 200                 TQ_SLEEP(tq, pp, "tq_destroy");
 201         }
 202 }
 203
 204 void
 205 taskqueue_free(struct taskqueue *queue)
 206 {
 207
 208         TQ_LOCK(queue);
 209         queue->tq_flags &= ~TQ_FLAGS_ACTIVE;
 210         taskqueue_terminate(queue->tq_threads, queue);
 211         KASSERT(LIST_EMPTY(&queue->tq_active), ("Tasks still running?"));
 212         KASSERT(queue->tq_callouts == 0, ("Armed timeout tasks"));
 213         mtx_destroy(&queue->tq_mutex);
 214         free(queue->tq_threads, M_TASKQUEUE);
 215         free(queue->tq_name, M_TASKQUEUE);
 216         free(queue, M_TASKQUEUE);
 217 }
 218
 219 static int
 220 taskqueue_enqueue_locked(struct taskqueue *queue, struct task *task)
 221 {
 222         struct task *ins;
 223         struct task *prev;
 224
 225         KASSERT(task->ta_func != NULL, ("enqueueing task with NULL func"));
 226         /*
 227          * Count multiple enqueues.
 228          */
 229         if (task->ta_pending) {
 230                 if (task->ta_pending < USHRT_MAX)
 231                         task->ta_pending++;
 232                 TQ_UNLOCK(queue);
 233                 return (0);
 234         }
 235
 236         /*
 237          * Optimise cases when all tasks use small set of priorities.
 238          * In case of only one priority we always insert at the end.
 239          * In case of two tq_hint typically gives the insertion point.
 240          * In case of more then two tq_hint should halve the search.
 241          */
 242         prev = STAILQ_LAST(&queue->tq_queue, task, ta_link);
 243         if (!prev || prev->ta_priority >= task->ta_priority) {
 244                 STAILQ_INSERT_TAIL(&queue->tq_queue, task, ta_link);
 245         } else {
 246                 prev = queue->tq_hint;
 247                 if (prev && prev->ta_priority >= task->ta_priority) {
 248                         ins = STAILQ_NEXT(prev, ta_link);
 249                 } else {
 250                         prev = NULL;
 251                         ins = STAILQ_FIRST(&queue->tq_queue);
 252                 }
 253                 for (; ins; prev = ins, ins = STAILQ_NEXT(ins, ta_link))
 254                         if (ins->ta_priority < task->ta_priority)
 255                                 break;
 256
 257                 if (prev) {
 258                         STAILQ_INSERT_AFTER(&queue->tq_queue, prev, task, ta_link);
 259                         queue->tq_hint = task;
 260                 } else
 261                         STAILQ_INSERT_HEAD(&queue->tq_queue, task, ta_link);
 262         }
 263
 264         task->ta_pending = 1;
 265         if ((queue->tq_flags & TQ_FLAGS_UNLOCKED_ENQUEUE) != 0)
 266                 TQ_UNLOCK(queue);
 267         if ((queue->tq_flags & TQ_FLAGS_BLOCKED) == 0)
 268                 queue->tq_enqueue(queue->tq_context);
 269         if ((queue->tq_flags & TQ_FLAGS_UNLOCKED_ENQUEUE) == 0)
 270                 TQ_UNLOCK(queue);
 271
 272         /* Return with lock released. */
 273         return (0);
 274 }
 275
 276 int
 277 taskqueue_enqueue(struct taskqueue *queue, struct task *task)
 278 {
 279         int res;
 280
 281         TQ_LOCK(queue);
 282         res = taskqueue_enqueue_locked(queue, task);
 283         /* The lock is released inside. */
 284
 285         return (res);
 286 }
 287
 288 static void
 289 taskqueue_timeout_func(void *arg)
 290 {
 291         struct taskqueue *queue;
 292         struct timeout_task *timeout_task;
 293
 294         timeout_task = arg;
 295         queue = timeout_task->q;
 296         KASSERT((timeout_task->f & DT_CALLOUT_ARMED) != 0, ("Stray timeout"));
 297         timeout_task->f &= ~DT_CALLOUT_ARMED;
 298         queue->tq_callouts--;
 299         taskqueue_enqueue_locked(timeout_task->q, &timeout_task->t);
 300         /* The lock is released inside. */
 301 }
 302
 303 int
 304 taskqueue_enqueue_timeout_sbt(struct taskqueue *queue,
 305     struct timeout_task *timeout_task, sbintime_t sbt, sbintime_t pr, int flags)
 306 {
 307         int res;
 308
 309         TQ_LOCK(queue);
 310         KASSERT(timeout_task->q == NULL || timeout_task->q == queue,
 311             ("Migrated queue"));
 312         timeout_task->q = queue;
 313         res = timeout_task->t.ta_pending;
 314         if (timeout_task->f & DT_DRAIN_IN_PROGRESS) {
 315                 /* Do nothing */
 316                 TQ_UNLOCK(queue);
 317                 res = -1;
 318         } else if (sbt == 0) {
 319                 taskqueue_enqueue_locked(queue, &timeout_task->t);
 320                 /* The lock is released inside. */
 321         } else {
 322                 if ((timeout_task->f & DT_CALLOUT_ARMED) != 0) {
 323                         res++;
 324                 } else {
 325                         queue->tq_callouts++;
 326                         timeout_task->f |= DT_CALLOUT_ARMED;
 327                         if (sbt < 0)
 328                                 sbt = -sbt; /* Ignore overflow. */
 329                 }
 330                 if (sbt > 0) {
 331                         if (queue->tq_spin)
 332                                 flags |= C_DIRECT_EXEC;
 333                         callout_reset_sbt(&timeout_task->c, sbt, pr,
 334                             taskqueue_timeout_func, timeout_task, flags);
 335                 }
 336                 TQ_UNLOCK(queue);
 337         }
 338         return (res);
 339 }
 340
 341 int
 342 taskqueue_enqueue_timeout(struct taskqueue *queue,
 343     struct timeout_task *ttask, int ticks)
 344 {
 345
 346         return (taskqueue_enqueue_timeout_sbt(queue, ttask, ticks * tick_sbt,
 347             0, C_HARDCLOCK));
 348 }
 349
 350 static void
 351 taskqueue_task_nop_fn(void *context, int pending)
 352 {
 353 }
 354
 355 /*
 356  * Block until all currently queued tasks in this taskqueue
 357  * have begun execution.  Tasks queued during execution of
 358  * this function are ignored.
 359  */
 360 static int
 361 taskqueue_drain_tq_queue(struct taskqueue *queue)
 362 {
 363         struct task t_barrier;
 364
 365         if (STAILQ_EMPTY(&queue->tq_queue))
 366                 return (0);
 367
 368         /*
 369          * Enqueue our barrier after all current tasks, but with
 370          * the highest priority so that newly queued tasks cannot
 371          * pass it.  Because of the high priority, we can not use
 372          * taskqueue_enqueue_locked directly (which drops the lock
 373          * anyway) so just insert it at tail while we have the
 374          * queue lock.
 375          */
 376         TASK_INIT(&t_barrier, UCHAR_MAX, taskqueue_task_nop_fn, &t_barrier);
 377         STAILQ_INSERT_TAIL(&queue->tq_queue, &t_barrier, ta_link);
 378         queue->tq_hint = &t_barrier;
 379         t_barrier.ta_pending = 1;
 380
 381         /*
 382          * Once the barrier has executed, all previously queued tasks
 383          * have completed or are currently executing.
 384          */
 385         while (t_barrier.ta_pending != 0)
 386                 TQ_SLEEP(queue, &t_barrier, "tq_qdrain");
 387         return (1);
 388 }
 389
 390 /*
 391  * Block until all currently executing tasks for this taskqueue
 392  * complete.  Tasks that begin execution during the execution
 393  * of this function are ignored.
 394  */
 395 static int
 396 taskqueue_drain_tq_active(struct taskqueue *queue)
 397 {
 398         struct taskqueue_busy *tb;
 399         u_int seq;
 400
 401         if (LIST_EMPTY(&queue->tq_active))
 402                 return (0);
 403
 404         /* Block taskq_terminate().*/
 405         queue->tq_callouts++;
 406
 407         /* Wait for any active task with sequence from the past. */
 408         seq = queue->tq_seq;
 409 restart:
 410         LIST_FOREACH(tb, &queue->tq_active, tb_link) {
 411                 if ((int)(tb->tb_seq - seq) <= 0) {
 412                         TQ_SLEEP(queue, tb->tb_running, "tq_adrain");
 413                         goto restart;
 414                 }
 415         }
 416
 417         /* Release taskqueue_terminate(). */
 418         queue->tq_callouts--;
 419         if ((queue->tq_flags & TQ_FLAGS_ACTIVE) == 0)
 420                 wakeup_one(queue->tq_threads);
 421         return (1);
 422 }
 423
 424 void
 425 taskqueue_block(struct taskqueue *queue)
 426 {
 427
 428         TQ_LOCK(queue);
 429         queue->tq_flags |= TQ_FLAGS_BLOCKED;
 430         TQ_UNLOCK(queue);
 431 }
 432
 433 void
 434 taskqueue_unblock(struct taskqueue *queue)
 435 {
 436
 437         TQ_LOCK(queue);
 438         queue->tq_flags &= ~TQ_FLAGS_BLOCKED;
 439         if (!STAILQ_EMPTY(&queue->tq_queue))
 440                 queue->tq_enqueue(queue->tq_context);
 441         TQ_UNLOCK(queue);
 442 }
 443
 444 static void
 445 taskqueue_run_locked(struct taskqueue *queue)
 446 {
 447         struct epoch_tracker et;
 448         struct taskqueue_busy tb;
 449         struct task *task;
 450         bool in_net_epoch;
 451         int pending;
 452
 453         KASSERT(queue != NULL, ("tq is NULL"));
 454         TQ_ASSERT_LOCKED(queue);
 455         tb.tb_running = NULL;
 456         LIST_INSERT_HEAD(&queue->tq_active, &tb, tb_link);
 457         in_net_epoch = false;
 458
 459         while ((task = STAILQ_FIRST(&queue->tq_queue)) != NULL) {
 460                 STAILQ_REMOVE_HEAD(&queue->tq_queue, ta_link);
 461                 if (queue->tq_hint == task)
 462                         queue->tq_hint = NULL;
 463                 pending = task->ta_pending;
 464                 task->ta_pending = 0;
 465                 tb.tb_running = task;
 466                 tb.tb_seq = ++queue->tq_seq;
 467                 TQ_UNLOCK(queue);
 468
 469                 KASSERT(task->ta_func != NULL, ("task->ta_func is NULL"));
 470                 if (!in_net_epoch && TASK_IS_NET(task)) {
 471                         in_net_epoch = true;
 472                         NET_EPOCH_ENTER(et);
 473                 } else if (in_net_epoch && !TASK_IS_NET(task)) {
 474                         NET_EPOCH_EXIT(et);
 475                         in_net_epoch = false;
 476                 }
 477                 task->ta_func(task->ta_context, pending);
 478
 479                 TQ_LOCK(queue);
 480                 wakeup(task);
 481         }
 482         if (in_net_epoch)
 483                 NET_EPOCH_EXIT(et);
 484         LIST_REMOVE(&tb, tb_link);
 485 }
 486
 487 void
 488 taskqueue_run(struct taskqueue *queue)
 489 {
 490
 491         TQ_LOCK(queue);
 492         taskqueue_run_locked(queue);
 493         TQ_UNLOCK(queue);
 494 }
 495
 496 static int
 497 task_is_running(struct taskqueue *queue, struct task *task)
 498 {
 499         struct taskqueue_busy *tb;
 500
 501         TQ_ASSERT_LOCKED(queue);
 502         LIST_FOREACH(tb, &queue->tq_active, tb_link) {
 503                 if (tb->tb_running == task)
 504                         return (1);
 505         }
 506         return (0);
 507 }
 508
 509 /*
 510  * Only use this function in single threaded contexts. It returns
 511  * non-zero if the given task is either pending or running. Else the
 512  * task is idle and can be queued again or freed.
 513  */
 514 int
 515 taskqueue_poll_is_busy(struct taskqueue *queue, struct task *task)
 516 {
 517         int retval;
 518
 519         TQ_LOCK(queue);
 520         retval = task->ta_pending > 0 || task_is_running(queue, task);
 521         TQ_UNLOCK(queue);
 522
 523         return (retval);
 524 }
 525
 526 static int
 527 taskqueue_cancel_locked(struct taskqueue *queue, struct task *task,
 528     u_int *pendp)
 529 {
 530
 531         if (task->ta_pending > 0) {
 532                 STAILQ_REMOVE(&queue->tq_queue, task, task, ta_link);
 533                 if (queue->tq_hint == task)
 534                         queue->tq_hint = NULL;
 535         }
 536         if (pendp != NULL)
 537                 *pendp = task->ta_pending;
 538         task->ta_pending = 0;
 539         return (task_is_running(queue, task) ? EBUSY : 0);
 540 }
 541
 542 int
 543 taskqueue_cancel(struct taskqueue *queue, struct task *task, u_int *pendp)
 544 {
 545         int error;
 546
 547         TQ_LOCK(queue);
 548         error = taskqueue_cancel_locked(queue, task, pendp);
 549         TQ_UNLOCK(queue);
 550
 551         return (error);
 552 }
 553
 554 int
 555 taskqueue_cancel_timeout(struct taskqueue *queue,
 556     struct timeout_task *timeout_task, u_int *pendp)
 557 {
 558         u_int pending, pending1;
 559         int error;
 560
 561         TQ_LOCK(queue);
 562         pending = !!(callout_stop(&timeout_task->c) > 0);
 563         error = taskqueue_cancel_locked(queue, &timeout_task->t, &pending1);
 564         if ((timeout_task->f & DT_CALLOUT_ARMED) != 0) {
 565                 timeout_task->f &= ~DT_CALLOUT_ARMED;
 566                 queue->tq_callouts--;
 567         }
 568         TQ_UNLOCK(queue);
 569
 570         if (pendp != NULL)
 571                 *pendp = pending + pending1;
 572         return (error);
 573 }
 574
 575 void
 576 taskqueue_drain(struct taskqueue *queue, struct task *task)
 577 {
 578
 579         if (!queue->tq_spin)
 580                 WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, NULL, __func__);
 581
 582         TQ_LOCK(queue);
 583         while (task->ta_pending != 0 || task_is_running(queue, task))
 584                 TQ_SLEEP(queue, task, "tq_drain");
 585         TQ_UNLOCK(queue);
 586 }
 587
 588 void
 589 taskqueue_drain_all(struct taskqueue *queue)
 590 {
 591
 592         if (!queue->tq_spin)
 593                 WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, NULL, __func__);
 594
 595         TQ_LOCK(queue);
 596         (void)taskqueue_drain_tq_queue(queue);
 597         (void)taskqueue_drain_tq_active(queue);
 598         TQ_UNLOCK(queue);
 599 }
 600
 601 void
 602 taskqueue_drain_timeout(struct taskqueue *queue,
 603     struct timeout_task *timeout_task)
 604 {
 605
 606         /*
 607          * Set flag to prevent timer from re-starting during drain:
 608          */
 609         TQ_LOCK(queue);
 610         KASSERT((timeout_task->f & DT_DRAIN_IN_PROGRESS) == 0,
 611             ("Drain already in progress"));
 612         timeout_task->f |= DT_DRAIN_IN_PROGRESS;
 613         TQ_UNLOCK(queue);
 614
 615         callout_drain(&timeout_task->c);
 616         taskqueue_drain(queue, &timeout_task->t);
 617
 618         /*
 619          * Clear flag to allow timer to re-start:
 620          */
 621         TQ_LOCK(queue);
 622         timeout_task->f &= ~DT_DRAIN_IN_PROGRESS;
 623         TQ_UNLOCK(queue);
 624 }
 625
 626 void
 627 taskqueue_quiesce(struct taskqueue *queue)
 628 {
 629         int ret;
 630
 631         TQ_LOCK(queue);
 632         do {
 633                 ret = taskqueue_drain_tq_queue(queue);
 634                 if (ret == 0)
 635                         ret = taskqueue_drain_tq_active(queue);
 636         } while (ret != 0);
 637         TQ_UNLOCK(queue);
 638 }
 639
 640 static void
 641 taskqueue_swi_enqueue(void *context)
 642 {
 643         swi_sched(taskqueue_ih, 0);
 644 }
 645
 646 static void
 647 taskqueue_swi_run(void *dummy)
 648 {
 649         taskqueue_run(taskqueue_swi);
 650 }
 651
 652 static void
 653 taskqueue_swi_giant_enqueue(void *context)
 654 {
 655         swi_sched(taskqueue_giant_ih, 0);
 656 }
 657
 658 static void
 659 taskqueue_swi_giant_run(void *dummy)
 660 {
 661         taskqueue_run(taskqueue_swi_giant);
 662 }
 663
 664 static int
 665 _taskqueue_start_threads(struct taskqueue **tqp, int count, int pri,
 666     cpuset_t *mask, struct proc *p, const char *name, va_list ap)
 667 {
 668         char ktname[MAXCOMLEN + 1];
 669         struct thread *td;
 670         struct taskqueue *tq;
 671         int i, error;
 672
 673         if (count <= 0)
 674                 return (EINVAL);
 675
 676         vsnprintf(ktname, sizeof(ktname), name, ap);
 677         tq = *tqp;
 678
 679         tq->tq_threads = malloc(sizeof(struct thread *) * count, M_TASKQUEUE,
 680             M_NOWAIT | M_ZERO);
 681         if (tq->tq_threads == NULL) {
 682                 printf("%s: no memory for %s threads\n", __func__, ktname);
 683                 return (ENOMEM);
 684         }
 685
 686         for (i = 0; i < count; i++) {
 687                 if (count == 1)
 688                         error = kthread_add(taskqueue_thread_loop, tqp, p,
 689                             &tq->tq_threads[i], RFSTOPPED, 0, "%s", ktname);
 690                 else
 691                         error = kthread_add(taskqueue_thread_loop, tqp, p,
 692                             &tq->tq_threads[i], RFSTOPPED, 0,
 693                             "%s_%d", ktname, i);
 694                 if (error) {
 695                         /* should be ok to continue, taskqueue_free will dtrt */
 696                         printf("%s: kthread_add(%s): error %d", __func__,
 697                             ktname, error);
 698                         tq->tq_threads[i] = NULL;               /* paranoid */
 699                 } else
 700                         tq->tq_tcount++;
 701         }
 702         if (tq->tq_tcount == 0) {
 703                 free(tq->tq_threads, M_TASKQUEUE);
 704                 tq->tq_threads = NULL;
 705                 return (ENOMEM);
 706         }
 707         for (i = 0; i < count; i++) {
 708                 if (tq->tq_threads[i] == NULL)
 709                         continue;
 710                 td = tq->tq_threads[i];
 711                 if (mask) {
 712                         error = cpuset_setthread(td->td_tid, mask);
 713                         /*
 714                          * Failing to pin is rarely an actual fatal error;
 715                          * it'll just affect performance.
 716                          */
 717                         if (error)
 718                                 printf("%s: curthread=%llu: can't pin; "
 719                                     "error=%d\n",
 720                                     __func__,
 721                                     (unsigned long long) td->td_tid,
 722                                     error);
 723                 }
 724                 thread_lock(td);
 725                 sched_prio(td, pri);
 726                 sched_add(td, SRQ_BORING);
 727         }
 728
 729         return (0);
 730 }
 731
 732 int
 733 taskqueue_start_threads(struct taskqueue **tqp, int count, int pri,
 734     const char *name, ...)
 735 {
 736         va_list ap;
 737         int error;
 738
 739         va_start(ap, name);
 740         error = _taskqueue_start_threads(tqp, count, pri, NULL, NULL, name, ap);
 741         va_end(ap);
 742         return (error);
 743 }
 744
 745 int
 746 taskqueue_start_threads_in_proc(struct taskqueue **tqp, int count, int pri,
 747     struct proc *proc, const char *name, ...)
 748 {
 749         va_list ap;
 750         int error;
 751
 752         va_start(ap, name);
 753         error = _taskqueue_start_threads(tqp, count, pri, NULL, proc, name, ap);
 754         va_end(ap);
 755         return (error);
 756 }
 757
 758 int
 759 taskqueue_start_threads_cpuset(struct taskqueue **tqp, int count, int pri,
 760     cpuset_t *mask, const char *name, ...)
 761 {
 762         va_list ap;
 763         int error;
 764
 765         va_start(ap, name);
 766         error = _taskqueue_start_threads(tqp, count, pri, mask, NULL, name, ap);
 767         va_end(ap);
 768         return (error);
 769 }
 770
 771 static inline void
 772 taskqueue_run_callback(struct taskqueue *tq,
 773     enum taskqueue_callback_type cb_type)
 774 {
 775         taskqueue_callback_fn tq_callback;
 776
 777         TQ_ASSERT_UNLOCKED(tq);
 778         tq_callback = tq->tq_callbacks[cb_type];
 779         if (tq_callback != NULL)
 780                 tq_callback(tq->tq_cb_contexts[cb_type]);
 781 }
 782
 783 void
 784 taskqueue_thread_loop(void *arg)
 785 {
 786         struct taskqueue **tqp, *tq;
 787
 788         tqp = arg;
 789         tq = *tqp;
 790         taskqueue_run_callback(tq, TASKQUEUE_CALLBACK_TYPE_INIT);
 791         TQ_LOCK(tq);
 792         while ((tq->tq_flags & TQ_FLAGS_ACTIVE) != 0) {
 793                 /* XXX ? */
 794                 taskqueue_run_locked(tq);
 795                 /*
 796                  * Because taskqueue_run() can drop tq_mutex, we need to
 797                  * check if the TQ_FLAGS_ACTIVE flag wasn't removed in the
 798                  * meantime, which means we missed a wakeup.
 799                  */
 800                 if ((tq->tq_flags & TQ_FLAGS_ACTIVE) == 0)
 801                         break;
 802                 TQ_SLEEP(tq, tq, "-");
 803         }
 804         taskqueue_run_locked(tq);
 805         /*
 806          * This thread is on its way out, so just drop the lock temporarily
 807          * in order to call the shutdown callback.  This allows the callback
 808          * to look at the taskqueue, even just before it dies.
 809          */
 810         TQ_UNLOCK(tq);
 811         taskqueue_run_callback(tq, TASKQUEUE_CALLBACK_TYPE_SHUTDOWN);
 812         TQ_LOCK(tq);
 813
 814         /* rendezvous with thread that asked us to terminate */
 815         tq->tq_tcount--;
 816         wakeup_one(tq->tq_threads);
 817         TQ_UNLOCK(tq);
 818         kthread_exit();
 819 }
 820
 821 void
 822 taskqueue_thread_enqueue(void *context)
 823 {
 824         struct taskqueue **tqp, *tq;
 825
 826         tqp = context;
 827         tq = *tqp;
 828         wakeup_any(tq);
 829 }
 830
 831 TASKQUEUE_DEFINE(swi, taskqueue_swi_enqueue, NULL,
 832                  swi_add(NULL, "task queue", taskqueue_swi_run, NULL, SWI_TQ,
 833                      INTR_MPSAFE, &taskqueue_ih));
 834
 835 TASKQUEUE_DEFINE(swi_giant, taskqueue_swi_giant_enqueue, NULL,
 836                  swi_add(NULL, "Giant taskq", taskqueue_swi_giant_run,
 837                      NULL, SWI_TQ_GIANT, 0, &taskqueue_giant_ih));
 838
 839 TASKQUEUE_DEFINE_THREAD(thread);
 840
 841 struct taskqueue *
 842 taskqueue_create_fast(const char *name, int mflags,
 843                  taskqueue_enqueue_fn enqueue, void *context)
 844 {
 845         return _taskqueue_create(name, mflags, enqueue, context,
 846                         MTX_SPIN, "fast_taskqueue");
 847 }
 848
 849 static void     *taskqueue_fast_ih;
 850
 851 static void
 852 taskqueue_fast_enqueue(void *context)
 853 {
 854         swi_sched(taskqueue_fast_ih, 0);
 855 }
 856
 857 static void
 858 taskqueue_fast_run(void *dummy)
 859 {
 860         taskqueue_run(taskqueue_fast);
 861 }
 862
 863 TASKQUEUE_FAST_DEFINE(fast, taskqueue_fast_enqueue, NULL,
 864         swi_add(NULL, "fast taskq", taskqueue_fast_run, NULL,
 865         SWI_TQ_FAST, INTR_MPSAFE, &taskqueue_fast_ih));
 866
 867 int
 868 taskqueue_member(struct taskqueue *queue, struct thread *td)
 869 {
 870         int i, j, ret = 0;
 871
 872         for (i = 0, j = 0; ; i++) {
 873                 if (queue->tq_threads[i] == NULL)
 874                         continue;
 875                 if (queue->tq_threads[i] == td) {
 876                         ret = 1;
 877                         break;
 878                 }
 879                 if (++j >= queue->tq_tcount)
 880                         break;
 881         }
 882         return (ret);
 883 }