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  * $FreeBSD: src/sys/kern/subr_taskqueue.c,v 1.69 2012/08/28 13:35:37 jhb Exp $"
  27  */
  28
  29 #include <sys/param.h>
  30 #include <sys/queue.h>
  31 #include <sys/systm.h>
  32 #include <sys/kernel.h>
  33 #include <sys/taskqueue.h>
  34 #include <sys/interrupt.h>
  35 #include <sys/lock.h>
  36 #include <sys/malloc.h>
  37 #include <sys/kthread.h>
  38 #include <sys/spinlock.h>
  39 #include <sys/spinlock2.h>
  40 #include <sys/serialize.h>
  41 #include <sys/proc.h>
  42
  43 MALLOC_DEFINE(M_TASKQUEUE, "taskqueue", "Task Queues");
  44
  45 static STAILQ_HEAD(taskqueue_list, taskqueue) taskqueue_queues;
  46 static struct lock      taskqueue_queues_lock;
  47
  48 struct taskqueue {
  49         STAILQ_ENTRY(taskqueue) tq_link;
  50         STAILQ_HEAD(, task)     tq_queue;
  51         const char              *tq_name;
  52         /* NOTE: tq must be locked before calling tq_enqueue */
  53         taskqueue_enqueue_fn    tq_enqueue;
  54         void                    *tq_context;
  55
  56         struct task             *tq_running;
  57         struct spinlock         tq_lock;
  58         struct thread           **tq_threads;
  59         int                     tq_tcount;
  60         int                     tq_flags;
  61         int                     tq_callouts;
  62 };
  63
  64 #define TQ_FLAGS_ACTIVE         (1 << 0)
  65 #define TQ_FLAGS_BLOCKED        (1 << 1)
  66 #define TQ_FLAGS_PENDING        (1 << 2)
  67
  68 #define DT_CALLOUT_ARMED        (1 << 0)
  69
  70 void
  71 _timeout_task_init(struct taskqueue *queue, struct timeout_task *timeout_task,
  72     int priority, task_fn_t func, void *context)
  73 {
  74
  75         TASK_INIT(&timeout_task->t, priority, func, context);
  76         callout_init(&timeout_task->c); /* XXX use callout_init_mp() */
  77         timeout_task->q = queue;
  78         timeout_task->f = 0;
  79 }
  80
  81 static void taskqueue_run(struct taskqueue *queue, int lock_held);
  82
  83 static __inline void
  84 TQ_LOCK_INIT(struct taskqueue *tq)
  85 {
  86         spin_init(&tq->tq_lock, "tqlock");
  87 }
  88
  89 static __inline void
  90 TQ_LOCK_UNINIT(struct taskqueue *tq)
  91 {
  92         spin_uninit(&tq->tq_lock);
  93 }
  94
  95 static __inline void
  96 TQ_LOCK(struct taskqueue *tq)
  97 {
  98         spin_lock(&tq->tq_lock);
  99 }
 100
 101 static __inline void
 102 TQ_UNLOCK(struct taskqueue *tq)
 103 {
 104         spin_unlock(&tq->tq_lock);
 105 }
 106
 107 static __inline void
 108 TQ_SLEEP(struct taskqueue *tq, void *ident, const char *wmesg)
 109 {
 110         ssleep(ident, &tq->tq_lock, 0, wmesg, 0);
 111 }
 112
 113 struct taskqueue *
 114 taskqueue_create(const char *name, int mflags,
 115                  taskqueue_enqueue_fn enqueue, void *context)
 116 {
 117         struct taskqueue *queue;
 118
 119         queue = kmalloc(sizeof(*queue), M_TASKQUEUE, mflags | M_ZERO);
 120         if (!queue)
 121                 return NULL;
 122         STAILQ_INIT(&queue->tq_queue);
 123         queue->tq_name = name;
 124         queue->tq_enqueue = enqueue;
 125         queue->tq_context = context;
 126         queue->tq_flags |= TQ_FLAGS_ACTIVE;
 127         TQ_LOCK_INIT(queue);
 128
 129         lockmgr(&taskqueue_queues_lock, LK_EXCLUSIVE);
 130         STAILQ_INSERT_TAIL(&taskqueue_queues, queue, tq_link);
 131         lockmgr(&taskqueue_queues_lock, LK_RELEASE);
 132
 133         return queue;
 134 }
 135
 136 /* NOTE: tq must be locked */
 137 static void
 138 taskqueue_terminate(struct thread **pp, struct taskqueue *tq)
 139 {
 140         while(tq->tq_tcount > 0) {
 141                 /* Unlock spinlock before wakeup() */
 142                 TQ_UNLOCK(tq);
 143                 wakeup(tq);
 144                 TQ_LOCK(tq);
 145                 TQ_SLEEP(tq, pp, "taskqueue_terminate");
 146         }
 147 }
 148
 149 void
 150 taskqueue_free(struct taskqueue *queue)
 151 {
 152         TQ_LOCK(queue);
 153         queue->tq_flags &= ~TQ_FLAGS_ACTIVE;
 154         taskqueue_run(queue, 1);
 155         taskqueue_terminate(queue->tq_threads, queue);
 156         TQ_UNLOCK(queue);
 157
 158         lockmgr(&taskqueue_queues_lock, LK_EXCLUSIVE);
 159         STAILQ_REMOVE(&taskqueue_queues, queue, taskqueue, tq_link);
 160         lockmgr(&taskqueue_queues_lock, LK_RELEASE);
 161
 162         TQ_LOCK_UNINIT(queue);
 163
 164         kfree(queue, M_TASKQUEUE);
 165 }
 166
 167 struct taskqueue *
 168 taskqueue_find(const char *name)
 169 {
 170         struct taskqueue *queue;
 171
 172         lockmgr(&taskqueue_queues_lock, LK_EXCLUSIVE);
 173         STAILQ_FOREACH(queue, &taskqueue_queues, tq_link) {
 174                 if (!strcmp(queue->tq_name, name)) {
 175                         lockmgr(&taskqueue_queues_lock, LK_RELEASE);
 176                         return queue;
 177                 }
 178         }
 179         lockmgr(&taskqueue_queues_lock, LK_RELEASE);
 180         return NULL;
 181 }
 182
 183 /*
 184  * NOTE!  If using the per-cpu taskqueues ``taskqueue_thread[mycpuid]'',
 185  * be sure NOT TO SHARE the ``task'' between CPUs.  TASKS ARE NOT LOCKED.
 186  * So either use a throwaway task which will only be enqueued once, or
 187  * use one task per CPU!
 188  */
 189 static int
 190 taskqueue_enqueue_locked(struct taskqueue *queue, struct task *task)
 191 {
 192         struct task *ins;
 193         struct task *prev;
 194
 195         /*
 196          * Don't allow new tasks on a queue which is being freed.
 197          */
 198         if ((queue->tq_flags & TQ_FLAGS_ACTIVE) == 0)
 199                 return EPIPE;
 200
 201         /*
 202          * Count multiple enqueues.
 203          */
 204         if (task->ta_pending) {
 205                 task->ta_pending++;
 206                 return 0;
 207         }
 208
 209         /*
 210          * Optimise the case when all tasks have the same priority.
 211          */
 212         prev = STAILQ_LAST(&queue->tq_queue, task, ta_link);
 213         if (!prev || prev->ta_priority >= task->ta_priority) {
 214                 STAILQ_INSERT_TAIL(&queue->tq_queue, task, ta_link);
 215         } else {
 216                 prev = NULL;
 217                 for (ins = STAILQ_FIRST(&queue->tq_queue); ins;
 218                      prev = ins, ins = STAILQ_NEXT(ins, ta_link))
 219                         if (ins->ta_priority < task->ta_priority)
 220                                 break;
 221
 222                 if (prev)
 223                         STAILQ_INSERT_AFTER(&queue->tq_queue, prev, task, ta_link);
 224                 else
 225                         STAILQ_INSERT_HEAD(&queue->tq_queue, task, ta_link);
 226         }
 227
 228         task->ta_pending = 1;
 229         if ((queue->tq_flags & TQ_FLAGS_BLOCKED) == 0) {
 230                 if (queue->tq_enqueue)
 231                         queue->tq_enqueue(queue->tq_context);
 232         } else {
 233                 queue->tq_flags |= TQ_FLAGS_PENDING;
 234         }
 235
 236         return 0;
 237 }
 238
 239 int
 240 taskqueue_enqueue(struct taskqueue *queue, struct task *task)
 241 {
 242         int res;
 243
 244         TQ_LOCK(queue);
 245         res = taskqueue_enqueue_locked(queue, task);
 246         TQ_UNLOCK(queue);
 247
 248         return (res);
 249 }
 250
 251 static void
 252 taskqueue_timeout_func(void *arg)
 253 {
 254         struct taskqueue *queue;
 255         struct timeout_task *timeout_task;
 256
 257         timeout_task = arg;
 258         queue = timeout_task->q;
 259
 260         TQ_LOCK(queue);
 261         KASSERT((timeout_task->f & DT_CALLOUT_ARMED) != 0, ("Stray timeout"));
 262         timeout_task->f &= ~DT_CALLOUT_ARMED;
 263         queue->tq_callouts--;
 264         taskqueue_enqueue_locked(timeout_task->q, &timeout_task->t);
 265         TQ_UNLOCK(queue);
 266 }
 267
 268 int
 269 taskqueue_enqueue_timeout(struct taskqueue *queue,
 270     struct timeout_task *timeout_task, int ticks)
 271 {
 272         int res;
 273
 274         TQ_LOCK(queue);
 275         KASSERT(timeout_task->q == NULL || timeout_task->q == queue,
 276                 ("Migrated queue"));
 277         timeout_task->q = queue;
 278         res = timeout_task->t.ta_pending;
 279         if (ticks == 0) {
 280                 taskqueue_enqueue_locked(queue, &timeout_task->t);
 281                 TQ_UNLOCK(queue);
 282         } else {
 283                 if ((timeout_task->f & DT_CALLOUT_ARMED) != 0) {
 284                         res++;
 285                 } else {
 286                         queue->tq_callouts++;
 287                         timeout_task->f |= DT_CALLOUT_ARMED;
 288                 }
 289                 TQ_UNLOCK(queue);
 290                 callout_reset(&timeout_task->c, ticks, taskqueue_timeout_func,
 291                               timeout_task);
 292         }
 293         return (res);
 294 }
 295
 296 void
 297 taskqueue_block(struct taskqueue *queue)
 298 {
 299         TQ_LOCK(queue);
 300         queue->tq_flags |= TQ_FLAGS_BLOCKED;
 301         TQ_UNLOCK(queue);
 302 }
 303
 304 void
 305 taskqueue_unblock(struct taskqueue *queue)
 306 {
 307         TQ_LOCK(queue);
 308         queue->tq_flags &= ~TQ_FLAGS_BLOCKED;
 309         if (queue->tq_flags & TQ_FLAGS_PENDING) {
 310                 queue->tq_flags &= ~TQ_FLAGS_PENDING;
 311                 if (queue->tq_enqueue)
 312                         queue->tq_enqueue(queue->tq_context);
 313         }
 314         TQ_UNLOCK(queue);
 315 }
 316
 317 static void
 318 taskqueue_run(struct taskqueue *queue, int lock_held)
 319 {
 320         struct task *task;
 321         int pending;
 322
 323         if (lock_held == 0)
 324                 TQ_LOCK(queue);
 325         while (STAILQ_FIRST(&queue->tq_queue)) {
 326                 /*
 327                  * Carefully remove the first task from the queue and
 328                  * zero its pending count.
 329                  */
 330                 task = STAILQ_FIRST(&queue->tq_queue);
 331                 STAILQ_REMOVE_HEAD(&queue->tq_queue, ta_link);
 332                 pending = task->ta_pending;
 333                 task->ta_pending = 0;
 334                 queue->tq_running = task;
 335
 336                 TQ_UNLOCK(queue);
 337                 task->ta_func(task->ta_context, pending);
 338                 queue->tq_running = NULL;
 339                 wakeup(task);
 340                 TQ_LOCK(queue);
 341         }
 342         if (lock_held == 0)
 343                 TQ_UNLOCK(queue);
 344 }
 345
 346 static int
 347 taskqueue_cancel_locked(struct taskqueue *queue, struct task *task,
 348     u_int *pendp)
 349 {
 350
 351         if (task->ta_pending > 0)
 352                 STAILQ_REMOVE(&queue->tq_queue, task, task, ta_link);
 353         if (pendp != NULL)
 354                 *pendp = task->ta_pending;
 355         task->ta_pending = 0;
 356         return (task == queue->tq_running ? EBUSY : 0);
 357 }
 358
 359 int
 360 taskqueue_cancel(struct taskqueue *queue, struct task *task, u_int *pendp)
 361 {
 362         int error;
 363
 364         TQ_LOCK(queue);
 365         error = taskqueue_cancel_locked(queue, task, pendp);
 366         TQ_UNLOCK(queue);
 367
 368         return (error);
 369 }
 370
 371 int
 372 taskqueue_cancel_timeout(struct taskqueue *queue,
 373                          struct timeout_task *timeout_task, u_int *pendp)
 374 {
 375         u_int pending, pending1;
 376         int error;
 377
 378         pending = !!callout_stop(&timeout_task->c);
 379         TQ_LOCK(queue);
 380         error = taskqueue_cancel_locked(queue, &timeout_task->t, &pending1);
 381         if ((timeout_task->f & DT_CALLOUT_ARMED) != 0) {
 382                 timeout_task->f &= ~DT_CALLOUT_ARMED;
 383                 queue->tq_callouts--;
 384         }
 385         TQ_UNLOCK(queue);
 386
 387         if (pendp != NULL)
 388                 *pendp = pending + pending1;
 389         return (error);
 390 }
 391
 392 void
 393 taskqueue_drain(struct taskqueue *queue, struct task *task)
 394 {
 395         TQ_LOCK(queue);
 396         while (task->ta_pending != 0 || task == queue->tq_running)
 397                 TQ_SLEEP(queue, task, "-");
 398         TQ_UNLOCK(queue);
 399 }
 400
 401 void
 402 taskqueue_drain_timeout(struct taskqueue *queue,
 403     struct timeout_task *timeout_task)
 404 {
 405         callout_cancel(&timeout_task->c);
 406         taskqueue_drain(queue, &timeout_task->t);
 407 }
 408
 409 static void
 410 taskqueue_swi_enqueue(void *context)
 411 {
 412         setsofttq();
 413 }
 414
 415 static void
 416 taskqueue_swi_run(void *arg, void *frame)
 417 {
 418         taskqueue_run(taskqueue_swi, 0);
 419 }
 420
 421 static void
 422 taskqueue_swi_mp_run(void *arg, void *frame)
 423 {
 424         taskqueue_run(taskqueue_swi_mp, 0);
 425 }
 426
 427 int
 428 taskqueue_start_threads(struct taskqueue **tqp, int count, int pri, int ncpu,
 429                         const char *fmt, ...)
 430 {
 431         __va_list ap;
 432         struct thread *td;
 433         struct taskqueue *tq;
 434         int i, error, cpu;
 435         char ktname[MAXCOMLEN];
 436
 437         if (count <= 0)
 438                 return EINVAL;
 439         /* catch call argument mistakes */
 440         KKASSERT(pri > 0 && pri < TDPRI_MAX);
 441
 442         tq = *tqp;
 443         cpu = ncpu;
 444
 445         __va_start(ap, fmt);
 446         kvsnprintf(ktname, MAXCOMLEN, fmt, ap);
 447         __va_end(ap);
 448
 449         tq->tq_threads = kmalloc(sizeof(struct thread *) * count, M_TASKQUEUE,
 450             M_WAITOK | M_ZERO);
 451
 452         for (i = 0; i < count; i++) {
 453                 /*
 454                  * If no specific cpu was specified and more than one thread
 455                  * is to be created, we distribute the threads amongst all
 456                  * cpus.
 457                  */
 458                 if ((ncpu <= -1) && (count > 1))
 459                         cpu = i%ncpus;
 460
 461                 if (count == 1) {
 462                         error = lwkt_create(taskqueue_thread_loop, tqp,
 463                                             &tq->tq_threads[i], NULL,
 464                                             TDF_NOSTART, cpu,
 465                                             "%s", ktname);
 466                 } else {
 467                         error = lwkt_create(taskqueue_thread_loop, tqp,
 468                                             &tq->tq_threads[i], NULL,
 469                                             TDF_NOSTART, cpu,
 470                                             "%s_%d", ktname, i);
 471                 }
 472                 if (error) {
 473                         kprintf("%s: lwkt_create(%s): error %d", __func__,
 474                             ktname, error);
 475                         tq->tq_threads[i] = NULL;
 476                 } else {
 477                         td = tq->tq_threads[i];
 478                         lwkt_setpri_initial(td, pri);
 479                         lwkt_schedule(td);
 480                         tq->tq_tcount++;
 481                 }
 482         }
 483
 484         return 0;
 485 }
 486
 487 void
 488 taskqueue_thread_loop(void *arg)
 489 {
 490         struct taskqueue **tqp, *tq;
 491
 492         tqp = arg;
 493         tq = *tqp;
 494         TQ_LOCK(tq);
 495         while ((tq->tq_flags & TQ_FLAGS_ACTIVE) != 0) {
 496                 taskqueue_run(tq, 1);
 497                 TQ_SLEEP(tq, tq, "tqthr");
 498         }
 499
 500         /* rendezvous with thread that asked us to terminate */
 501         tq->tq_tcount--;
 502         TQ_UNLOCK(tq);
 503         wakeup_one(tq->tq_threads);
 504         lwkt_exit();
 505 }
 506
 507 /* NOTE: tq must be locked */
 508 void
 509 taskqueue_thread_enqueue(void *context)
 510 {
 511         struct taskqueue **tqp, *tq;
 512
 513         tqp = context;
 514         tq = *tqp;
 515
 516         /* Unlock spinlock before wakeup_one() */
 517         TQ_UNLOCK(tq);
 518         wakeup_one(tq);
 519         TQ_LOCK(tq);
 520 }
 521
 522 TASKQUEUE_DEFINE(swi, taskqueue_swi_enqueue, 0,
 523          register_swi(SWI_TQ, taskqueue_swi_run, NULL, "swi_taskq", NULL, -1));
 524 /*
 525  * XXX: possibly use a different SWI_TQ_MP or so.
 526  * related: sys/interrupt.h
 527  * related: platform/XXX/isa/ipl_funcs.c
 528  */
 529 TASKQUEUE_DEFINE(swi_mp, taskqueue_swi_enqueue, 0,
 530     register_swi_mp(SWI_TQ, taskqueue_swi_mp_run, NULL, "swi_mp_taskq", NULL,
 531                     -1));
 532
 533 struct taskqueue *taskqueue_thread[MAXCPU];
 534
 535 static void
 536 taskqueue_init(void)
 537 {
 538         int cpu;
 539
 540         lockinit(&taskqueue_queues_lock, "tqqueues", 0, 0);
 541         STAILQ_INIT(&taskqueue_queues);
 542
 543         for (cpu = 0; cpu < ncpus; cpu++) {
 544                 taskqueue_thread[cpu] = taskqueue_create("thread", M_INTWAIT,
 545                     taskqueue_thread_enqueue, &taskqueue_thread[cpu]);
 546                 taskqueue_start_threads(&taskqueue_thread[cpu], 1,
 547                     TDPRI_KERN_DAEMON, cpu, "taskq_cpu %d", cpu);
 548         }
 549 }
 550
 551 SYSINIT(taskqueueinit, SI_SUB_PRE_DRIVERS, SI_ORDER_ANY, taskqueue_init, NULL);