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/thread2.h>
  39 #include <sys/spinlock.h>
  40 #include <sys/spinlock2.h>
  41 #include <sys/serialize.h>
  42 #include <sys/proc.h>
  43 #include <machine/varargs.h>
  44
  45 MALLOC_DEFINE(M_TASKQUEUE, "taskqueue", "Task Queues");
  46
  47 static STAILQ_HEAD(taskqueue_list, taskqueue) taskqueue_queues;
  48 static struct lock      taskqueue_queues_lock;
  49
  50 struct taskqueue {
  51         STAILQ_ENTRY(taskqueue) tq_link;
  52         STAILQ_HEAD(, task)     tq_queue;
  53         const char              *tq_name;
  54         taskqueue_enqueue_fn    tq_enqueue;
  55         void                    *tq_context;
  56
  57         struct task             *tq_running;
  58         struct spinlock         tq_lock;
  59         struct thread           **tq_threads;
  60         int                     tq_tcount;
  61         int                     tq_flags;
  62         int                     tq_callouts;
  63 };
  64
  65 #define TQ_FLAGS_ACTIVE         (1 << 0)
  66 #define TQ_FLAGS_BLOCKED        (1 << 1)
  67 #define TQ_FLAGS_PENDING        (1 << 2)
  68
  69 #define DT_CALLOUT_ARMED        (1 << 0)
  70
  71 void
  72 _timeout_task_init(struct taskqueue *queue, struct timeout_task *timeout_task,
  73     int priority, task_fn_t func, void *context)
  74 {
  75
  76         TASK_INIT(&timeout_task->t, priority, func, context);
  77         callout_init(&timeout_task->c);
  78         timeout_task->q = queue;
  79         timeout_task->f = 0;
  80 }
  81
  82 static void taskqueue_run(struct taskqueue *queue, int lock_held);
  83
  84 static __inline void
  85 TQ_LOCK_INIT(struct taskqueue *tq)
  86 {
  87         spin_init(&tq->tq_lock);
  88 }
  89
  90 static __inline void
  91 TQ_LOCK_UNINIT(struct taskqueue *tq)
  92 {
  93         spin_uninit(&tq->tq_lock);
  94 }
  95
  96 static __inline void
  97 TQ_LOCK(struct taskqueue *tq)
  98 {
  99         spin_lock(&tq->tq_lock);
 100 }
 101
 102 static __inline void
 103 TQ_UNLOCK(struct taskqueue *tq)
 104 {
 105         spin_unlock(&tq->tq_lock);
 106 }
 107
 108 static __inline void
 109 TQ_SLEEP(struct taskqueue *tq, void *ident, const char *wmesg)
 110 {
 111         ssleep(ident, &tq->tq_lock, 0, wmesg, 0);
 112 }
 113
 114 struct taskqueue *
 115 taskqueue_create(const char *name, int mflags,
 116                  taskqueue_enqueue_fn enqueue, void *context)
 117 {
 118         struct taskqueue *queue;
 119
 120         queue = kmalloc(sizeof(*queue), M_TASKQUEUE, mflags | M_ZERO);
 121         if (!queue)
 122                 return NULL;
 123         STAILQ_INIT(&queue->tq_queue);
 124         queue->tq_name = name;
 125         queue->tq_enqueue = enqueue;
 126         queue->tq_context = context;
 127         queue->tq_flags |= TQ_FLAGS_ACTIVE;
 128         TQ_LOCK_INIT(queue);
 129
 130         lockmgr(&taskqueue_queues_lock, LK_EXCLUSIVE);
 131         STAILQ_INSERT_TAIL(&taskqueue_queues, queue, tq_link);
 132         lockmgr(&taskqueue_queues_lock, LK_RELEASE);
 133
 134         return queue;
 135 }
 136
 137 static void
 138 taskqueue_terminate(struct thread **pp, struct taskqueue *tq)
 139 {
 140         while(tq->tq_tcount > 0) {
 141                 wakeup(tq);
 142                 TQ_SLEEP(tq, pp, "taskqueue_terminate");
 143         }
 144 }
 145
 146 void
 147 taskqueue_free(struct taskqueue *queue)
 148 {
 149         TQ_LOCK(queue);
 150         queue->tq_flags &= ~TQ_FLAGS_ACTIVE;
 151         taskqueue_run(queue, 1);
 152         taskqueue_terminate(queue->tq_threads, queue);
 153         TQ_UNLOCK(queue);
 154
 155         lockmgr(&taskqueue_queues_lock, LK_EXCLUSIVE);
 156         STAILQ_REMOVE(&taskqueue_queues, queue, taskqueue, tq_link);
 157         lockmgr(&taskqueue_queues_lock, LK_RELEASE);
 158
 159         TQ_LOCK_UNINIT(queue);
 160
 161         kfree(queue, M_TASKQUEUE);
 162 }
 163
 164 struct taskqueue *
 165 taskqueue_find(const char *name)
 166 {
 167         struct taskqueue *queue;
 168
 169         lockmgr(&taskqueue_queues_lock, LK_EXCLUSIVE);
 170         STAILQ_FOREACH(queue, &taskqueue_queues, tq_link) {
 171                 if (!strcmp(queue->tq_name, name)) {
 172                         lockmgr(&taskqueue_queues_lock, LK_RELEASE);
 173                         return queue;
 174                 }
 175         }
 176         lockmgr(&taskqueue_queues_lock, LK_RELEASE);
 177         return NULL;
 178 }
 179
 180 /*
 181  * NOTE!  If using the per-cpu taskqueues ``taskqueue_thread[mycpuid]'',
 182  * be sure NOT TO SHARE the ``task'' between CPUs.  TASKS ARE NOT LOCKED.
 183  * So either use a throwaway task which will only be enqueued once, or
 184  * use one task per CPU!
 185  */
 186 static int
 187 taskqueue_enqueue_locked(struct taskqueue *queue, struct task *task)
 188 {
 189         struct task *ins;
 190         struct task *prev;
 191
 192         /*
 193          * Don't allow new tasks on a queue which is being freed.
 194          */
 195         if ((queue->tq_flags & TQ_FLAGS_ACTIVE) == 0)
 196                 return EPIPE;
 197
 198         /*
 199          * Count multiple enqueues.
 200          */
 201         if (task->ta_pending) {
 202                 task->ta_pending++;
 203                 return 0;
 204         }
 205
 206         /*
 207          * Optimise the case when all tasks have the same priority.
 208          */
 209         prev = STAILQ_LAST(&queue->tq_queue, task, ta_link);
 210         if (!prev || prev->ta_priority >= task->ta_priority) {
 211                 STAILQ_INSERT_TAIL(&queue->tq_queue, task, ta_link);
 212         } else {
 213                 prev = NULL;
 214                 for (ins = STAILQ_FIRST(&queue->tq_queue); ins;
 215                      prev = ins, ins = STAILQ_NEXT(ins, ta_link))
 216                         if (ins->ta_priority < task->ta_priority)
 217                                 break;
 218
 219                 if (prev)
 220                         STAILQ_INSERT_AFTER(&queue->tq_queue, prev, task, ta_link);
 221                 else
 222                         STAILQ_INSERT_HEAD(&queue->tq_queue, task, ta_link);
 223         }
 224
 225         task->ta_pending = 1;
 226         if ((queue->tq_flags & TQ_FLAGS_BLOCKED) == 0) {
 227                 if (queue->tq_enqueue)
 228                         queue->tq_enqueue(queue->tq_context);
 229         } else {
 230                 queue->tq_flags |= TQ_FLAGS_PENDING;
 231         }
 232
 233         return 0;
 234 }
 235
 236 int
 237 taskqueue_enqueue(struct taskqueue *queue, struct task *task)
 238 {
 239         int res;
 240
 241         TQ_LOCK(queue);
 242         res = taskqueue_enqueue_locked(queue, task);
 243         TQ_UNLOCK(queue);
 244
 245         return (res);
 246 }
 247
 248 static void
 249 taskqueue_timeout_func(void *arg)
 250 {
 251         struct taskqueue *queue;
 252         struct timeout_task *timeout_task;
 253
 254         timeout_task = arg;
 255         queue = timeout_task->q;
 256         KASSERT((timeout_task->f & DT_CALLOUT_ARMED) != 0, ("Stray timeout"));
 257         timeout_task->f &= ~DT_CALLOUT_ARMED;
 258         queue->tq_callouts--;
 259         taskqueue_enqueue_locked(timeout_task->q, &timeout_task->t);
 260 }
 261
 262 int
 263 taskqueue_enqueue_timeout(struct taskqueue *queue,
 264     struct timeout_task *timeout_task, int ticks)
 265 {
 266         int res;
 267
 268         TQ_LOCK(queue);
 269         KASSERT(timeout_task->q == NULL || timeout_task->q == queue,
 270             ("Migrated queue"));
 271         timeout_task->q = queue;
 272         res = timeout_task->t.ta_pending;
 273         if (ticks == 0) {
 274                 taskqueue_enqueue_locked(queue, &timeout_task->t);
 275         } else {
 276                 if ((timeout_task->f & DT_CALLOUT_ARMED) != 0) {
 277                         res++;
 278                 } else {
 279                         queue->tq_callouts++;
 280                         timeout_task->f |= DT_CALLOUT_ARMED;
 281                 }
 282                 callout_reset(&timeout_task->c, ticks, taskqueue_timeout_func,
 283                     timeout_task);
 284         }
 285         TQ_UNLOCK(queue);
 286         return (res);
 287 }
 288
 289 void
 290 taskqueue_block(struct taskqueue *queue)
 291 {
 292         TQ_LOCK(queue);
 293         queue->tq_flags |= TQ_FLAGS_BLOCKED;
 294         TQ_UNLOCK(queue);
 295 }
 296
 297 void
 298 taskqueue_unblock(struct taskqueue *queue)
 299 {
 300         TQ_LOCK(queue);
 301         queue->tq_flags &= ~TQ_FLAGS_BLOCKED;
 302         if (queue->tq_flags & TQ_FLAGS_PENDING) {
 303                 queue->tq_flags &= ~TQ_FLAGS_PENDING;
 304                 if (queue->tq_enqueue)
 305                         queue->tq_enqueue(queue->tq_context);
 306         }
 307         TQ_UNLOCK(queue);
 308 }
 309
 310 void
 311 taskqueue_run(struct taskqueue *queue, int lock_held)
 312 {
 313         struct task *task;
 314         int pending;
 315
 316         if (lock_held == 0)
 317                 TQ_LOCK(queue);
 318         while (STAILQ_FIRST(&queue->tq_queue)) {
 319                 /*
 320                  * Carefully remove the first task from the queue and
 321                  * zero its pending count.
 322                  */
 323                 task = STAILQ_FIRST(&queue->tq_queue);
 324                 STAILQ_REMOVE_HEAD(&queue->tq_queue, ta_link);
 325                 pending = task->ta_pending;
 326                 task->ta_pending = 0;
 327                 queue->tq_running = task;
 328                 TQ_UNLOCK(queue);
 329
 330                 task->ta_func(task->ta_context, pending);
 331
 332                 TQ_LOCK(queue);
 333                 queue->tq_running = NULL;
 334                 wakeup(task);
 335         }
 336         if (lock_held == 0)
 337                 TQ_UNLOCK(queue);
 338 }
 339
 340 static int
 341 taskqueue_cancel_locked(struct taskqueue *queue, struct task *task,
 342     u_int *pendp)
 343 {
 344
 345         if (task->ta_pending > 0)
 346                 STAILQ_REMOVE(&queue->tq_queue, task, task, ta_link);
 347         if (pendp != NULL)
 348                 *pendp = task->ta_pending;
 349         task->ta_pending = 0;
 350         return (task == queue->tq_running ? EBUSY : 0);
 351 }
 352
 353 int
 354 taskqueue_cancel(struct taskqueue *queue, struct task *task, u_int *pendp)
 355 {
 356         u_int pending;
 357         int error;
 358
 359         TQ_LOCK(queue);
 360         pending = task->ta_pending;
 361         error = taskqueue_cancel_locked(queue, task, pendp);
 362         TQ_UNLOCK(queue);
 363
 364         return (error);
 365 }
 366
 367 int
 368 taskqueue_cancel_timeout(struct taskqueue *queue,
 369     struct timeout_task *timeout_task, u_int *pendp)
 370 {
 371         u_int pending, pending1;
 372         int error;
 373
 374         TQ_LOCK(queue);
 375         pending = !!callout_stop(&timeout_task->c);
 376         error = taskqueue_cancel_locked(queue, &timeout_task->t, &pending1);
 377         if ((timeout_task->f & DT_CALLOUT_ARMED) != 0) {
 378                 timeout_task->f &= ~DT_CALLOUT_ARMED;
 379                 queue->tq_callouts--;
 380         }
 381         TQ_UNLOCK(queue);
 382
 383         if (pendp != NULL)
 384                 *pendp = pending + pending1;
 385         return (error);
 386 }
 387
 388 void
 389 taskqueue_drain(struct taskqueue *queue, struct task *task)
 390 {
 391         TQ_LOCK(queue);
 392         while (task->ta_pending != 0 || task == queue->tq_running)
 393                 TQ_SLEEP(queue, task, "-");
 394         TQ_UNLOCK(queue);
 395 }
 396
 397 void
 398 taskqueue_drain_timeout(struct taskqueue *queue,
 399     struct timeout_task *timeout_task)
 400 {
 401
 402         callout_stop_sync(&timeout_task->c);
 403         taskqueue_drain(queue, &timeout_task->t);
 404 }
 405
 406 static void
 407 taskqueue_swi_enqueue(void *context)
 408 {
 409         setsofttq();
 410 }
 411
 412 static void
 413 taskqueue_swi_run(void *arg, void *frame)
 414 {
 415         taskqueue_run(taskqueue_swi, 0);
 416 }
 417
 418 static void
 419 taskqueue_swi_mp_run(void *arg, void *frame)
 420 {
 421         taskqueue_run(taskqueue_swi_mp, 0);
 422 }
 423
 424 int
 425 taskqueue_start_threads(struct taskqueue **tqp, int count, int pri, int ncpu,
 426                         const char *fmt, ...)
 427 {
 428         __va_list ap;
 429         struct thread *td;
 430         struct taskqueue *tq;
 431         int i, error, cpu;
 432         char ktname[MAXCOMLEN];
 433
 434         if (count <= 0)
 435                 return EINVAL;
 436
 437         tq = *tqp;
 438         cpu = ncpu;
 439
 440         __va_start(ap, fmt);
 441         kvsnprintf(ktname, MAXCOMLEN, fmt, ap);
 442         __va_end(ap);
 443
 444         tq->tq_threads = kmalloc(sizeof(struct thread *) * count, M_TASKQUEUE,
 445             M_WAITOK | M_ZERO);
 446
 447         for (i = 0; i < count; i++) {
 448                 /*
 449                  * If no specific cpu was specified and more than one thread
 450                  * is to be created, we distribute the threads amongst all
 451                  * cpus.
 452                  */
 453                 if ((ncpu <= -1) && (count > 1))
 454                         cpu = i%ncpus;
 455
 456                 if (count == 1) {
 457                         error = lwkt_create(taskqueue_thread_loop, tqp,
 458                                             &tq->tq_threads[i], NULL,
 459                                             TDF_NOSTART, cpu,
 460                                             "%s", ktname);
 461                 } else {
 462                         error = lwkt_create(taskqueue_thread_loop, tqp,
 463                                             &tq->tq_threads[i], NULL,
 464                                             TDF_NOSTART, cpu,
 465                                             "%s_%d", ktname, i);
 466                 }
 467                 if (error) {
 468                         kprintf("%s: lwkt_create(%s): error %d", __func__,
 469                             ktname, error);
 470                         tq->tq_threads[i] = NULL;
 471                 } else {
 472                         td = tq->tq_threads[i];
 473                         lwkt_setpri_initial(td, pri);
 474                         lwkt_schedule(td);
 475                         tq->tq_tcount++;
 476                 }
 477         }
 478
 479         return 0;
 480 }
 481
 482 void
 483 taskqueue_thread_loop(void *arg)
 484 {
 485         struct taskqueue **tqp, *tq;
 486
 487         tqp = arg;
 488         tq = *tqp;
 489         TQ_LOCK(tq);
 490         while ((tq->tq_flags & TQ_FLAGS_ACTIVE) != 0) {
 491                 taskqueue_run(tq, 1);
 492                 TQ_SLEEP(tq, tq, "tqthr");
 493         }
 494
 495         /* rendezvous with thread that asked us to terminate */
 496         tq->tq_tcount--;
 497         wakeup_one(tq->tq_threads);
 498         TQ_UNLOCK(tq);
 499         lwkt_exit();
 500 }
 501
 502 void
 503 taskqueue_thread_enqueue(void *context)
 504 {
 505         struct taskqueue **tqp, *tq;
 506
 507         tqp = context;
 508         tq = *tqp;
 509
 510         wakeup_one(tq);
 511 }
 512
 513 TASKQUEUE_DEFINE(swi, taskqueue_swi_enqueue, 0,
 514          register_swi(SWI_TQ, taskqueue_swi_run, NULL, "swi_taskq", NULL, -1));
 515 /*
 516  * XXX: possibly use a different SWI_TQ_MP or so.
 517  * related: sys/interrupt.h
 518  * related: platform/XXX/isa/ipl_funcs.c
 519  */
 520 TASKQUEUE_DEFINE(swi_mp, taskqueue_swi_enqueue, 0,
 521     register_swi_mp(SWI_TQ, taskqueue_swi_mp_run, NULL, "swi_mp_taskq", NULL,
 522                     -1));
 523
 524 struct taskqueue *taskqueue_thread[MAXCPU];
 525
 526 static void
 527 taskqueue_init(void)
 528 {
 529         int cpu;
 530
 531         lockinit(&taskqueue_queues_lock, "tqqueues", 0, 0);
 532         STAILQ_INIT(&taskqueue_queues);
 533
 534         for (cpu = 0; cpu < ncpus; cpu++) {
 535                 taskqueue_thread[cpu] = taskqueue_create("thread", M_INTWAIT,
 536                     taskqueue_thread_enqueue, &taskqueue_thread[cpu]);
 537                 taskqueue_start_threads(&taskqueue_thread[cpu], 1,
 538                     TDPRI_KERN_DAEMON, cpu, "taskq_cpu %d", cpu);
 539         }
 540 }
 541
 542 SYSINIT(taskqueueinit, SI_SUB_PRE_DRIVERS, SI_ORDER_ANY, taskqueue_init, NULL);