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
  44 MALLOC_DEFINE(M_TASKQUEUE, "taskqueue", "Task Queues");
  45
  46 static STAILQ_HEAD(taskqueue_list, taskqueue) taskqueue_queues;
  47 static struct lock      taskqueue_queues_lock;
  48
  49 struct taskqueue {
  50         STAILQ_ENTRY(taskqueue) tq_link;
  51         STAILQ_HEAD(, task)     tq_queue;
  52         const char              *tq_name;
  53         /* NOTE: tq must be locked before calling tq_enqueue */
  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); /* XXX use callout_init_mp() */
  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, "tqlock");
  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 /* NOTE: tq must be locked */
 138 static void
 139 taskqueue_terminate(struct thread **pp, struct taskqueue *tq)
 140 {
 141         while(tq->tq_tcount > 0) {
 142                 /* Unlock spinlock before wakeup() */
 143                 TQ_UNLOCK(tq);
 144                 wakeup(tq);
 145                 TQ_LOCK(tq);
 146                 TQ_SLEEP(tq, pp, "taskqueue_terminate");
 147         }
 148 }
 149
 150 void
 151 taskqueue_free(struct taskqueue *queue)
 152 {
 153         TQ_LOCK(queue);
 154         queue->tq_flags &= ~TQ_FLAGS_ACTIVE;
 155         taskqueue_run(queue, 1);
 156         taskqueue_terminate(queue->tq_threads, queue);
 157         TQ_UNLOCK(queue);
 158
 159         lockmgr(&taskqueue_queues_lock, LK_EXCLUSIVE);
 160         STAILQ_REMOVE(&taskqueue_queues, queue, taskqueue, tq_link);
 161         lockmgr(&taskqueue_queues_lock, LK_RELEASE);
 162
 163         TQ_LOCK_UNINIT(queue);
 164
 165         kfree(queue, M_TASKQUEUE);
 166 }
 167
 168 struct taskqueue *
 169 taskqueue_find(const char *name)
 170 {
 171         struct taskqueue *queue;
 172
 173         lockmgr(&taskqueue_queues_lock, LK_EXCLUSIVE);
 174         STAILQ_FOREACH(queue, &taskqueue_queues, tq_link) {
 175                 if (!strcmp(queue->tq_name, name)) {
 176                         lockmgr(&taskqueue_queues_lock, LK_RELEASE);
 177                         return queue;
 178                 }
 179         }
 180         lockmgr(&taskqueue_queues_lock, LK_RELEASE);
 181         return NULL;
 182 }
 183
 184 /*
 185  * NOTE!  If using the per-cpu taskqueues ``taskqueue_thread[mycpuid]'',
 186  * be sure NOT TO SHARE the ``task'' between CPUs.  TASKS ARE NOT LOCKED.
 187  * So either use a throwaway task which will only be enqueued once, or
 188  * use one task per CPU!
 189  */
 190 static int
 191 taskqueue_enqueue_locked(struct taskqueue *queue, struct task *task)
 192 {
 193         struct task *ins;
 194         struct task *prev;
 195
 196         /*
 197          * Don't allow new tasks on a queue which is being freed.
 198          */
 199         if ((queue->tq_flags & TQ_FLAGS_ACTIVE) == 0)
 200                 return EPIPE;
 201
 202         /*
 203          * Count multiple enqueues.
 204          */
 205         if (task->ta_pending) {
 206                 task->ta_pending++;
 207                 return 0;
 208         }
 209
 210         /*
 211          * Optimise the case when all tasks have the same priority.
 212          */
 213         prev = STAILQ_LAST(&queue->tq_queue, task, ta_link);
 214         if (!prev || prev->ta_priority >= task->ta_priority) {
 215                 STAILQ_INSERT_TAIL(&queue->tq_queue, task, ta_link);
 216         } else {
 217                 prev = NULL;
 218                 for (ins = STAILQ_FIRST(&queue->tq_queue); ins;
 219                      prev = ins, ins = STAILQ_NEXT(ins, ta_link))
 220                         if (ins->ta_priority < task->ta_priority)
 221                                 break;
 222
 223                 if (prev)
 224                         STAILQ_INSERT_AFTER(&queue->tq_queue, prev, task, ta_link);
 225                 else
 226                         STAILQ_INSERT_HEAD(&queue->tq_queue, task, ta_link);
 227         }
 228
 229         task->ta_pending = 1;
 230         if ((queue->tq_flags & TQ_FLAGS_BLOCKED) == 0) {
 231                 if (queue->tq_enqueue)
 232                         queue->tq_enqueue(queue->tq_context);
 233         } else {
 234                 queue->tq_flags |= TQ_FLAGS_PENDING;
 235         }
 236
 237         return 0;
 238 }
 239
 240 int
 241 taskqueue_enqueue(struct taskqueue *queue, struct task *task)
 242 {
 243         int res;
 244
 245         TQ_LOCK(queue);
 246         res = taskqueue_enqueue_locked(queue, task);
 247         TQ_UNLOCK(queue);
 248
 249         return (res);
 250 }
 251
 252 static void
 253 taskqueue_timeout_func(void *arg)
 254 {
 255         struct taskqueue *queue;
 256         struct timeout_task *timeout_task;
 257
 258         timeout_task = arg;
 259         queue = timeout_task->q;
 260
 261         TQ_LOCK(queue);
 262         KASSERT((timeout_task->f & DT_CALLOUT_ARMED) != 0, ("Stray timeout"));
 263         timeout_task->f &= ~DT_CALLOUT_ARMED;
 264         queue->tq_callouts--;
 265         taskqueue_enqueue_locked(timeout_task->q, &timeout_task->t);
 266         TQ_UNLOCK(queue);
 267 }
 268
 269 int
 270 taskqueue_enqueue_timeout(struct taskqueue *queue,
 271     struct timeout_task *timeout_task, int ticks)
 272 {
 273         int res;
 274
 275         TQ_LOCK(queue);
 276         KASSERT(timeout_task->q == NULL || timeout_task->q == queue,
 277                 ("Migrated queue"));
 278         timeout_task->q = queue;
 279         res = timeout_task->t.ta_pending;
 280         if (ticks == 0) {
 281                 taskqueue_enqueue_locked(queue, &timeout_task->t);
 282                 TQ_UNLOCK(queue);
 283         } else {
 284                 if ((timeout_task->f & DT_CALLOUT_ARMED) != 0) {
 285                         res++;
 286                 } else {
 287                         queue->tq_callouts++;
 288                         timeout_task->f |= DT_CALLOUT_ARMED;
 289                 }
 290                 TQ_UNLOCK(queue);
 291                 callout_reset(&timeout_task->c, ticks, taskqueue_timeout_func,
 292                               timeout_task);
 293         }
 294         return (res);
 295 }
 296
 297 void
 298 taskqueue_block(struct taskqueue *queue)
 299 {
 300         TQ_LOCK(queue);
 301         queue->tq_flags |= TQ_FLAGS_BLOCKED;
 302         TQ_UNLOCK(queue);
 303 }
 304
 305 void
 306 taskqueue_unblock(struct taskqueue *queue)
 307 {
 308         TQ_LOCK(queue);
 309         queue->tq_flags &= ~TQ_FLAGS_BLOCKED;
 310         if (queue->tq_flags & TQ_FLAGS_PENDING) {
 311                 queue->tq_flags &= ~TQ_FLAGS_PENDING;
 312                 if (queue->tq_enqueue)
 313                         queue->tq_enqueue(queue->tq_context);
 314         }
 315         TQ_UNLOCK(queue);
 316 }
 317
 318 static void
 319 taskqueue_run(struct taskqueue *queue, int lock_held)
 320 {
 321         struct task *task;
 322         int pending;
 323
 324         if (lock_held == 0)
 325                 TQ_LOCK(queue);
 326         while (STAILQ_FIRST(&queue->tq_queue)) {
 327                 /*
 328                  * Carefully remove the first task from the queue and
 329                  * zero its pending count.
 330                  */
 331                 task = STAILQ_FIRST(&queue->tq_queue);
 332                 STAILQ_REMOVE_HEAD(&queue->tq_queue, ta_link);
 333                 pending = task->ta_pending;
 334                 task->ta_pending = 0;
 335                 queue->tq_running = task;
 336
 337                 TQ_UNLOCK(queue);
 338                 task->ta_func(task->ta_context, pending);
 339                 queue->tq_running = NULL;
 340                 wakeup(task);
 341                 TQ_LOCK(queue);
 342         }
 343         if (lock_held == 0)
 344                 TQ_UNLOCK(queue);
 345 }
 346
 347 static int
 348 taskqueue_cancel_locked(struct taskqueue *queue, struct task *task,
 349     u_int *pendp)
 350 {
 351
 352         if (task->ta_pending > 0)
 353                 STAILQ_REMOVE(&queue->tq_queue, task, task, ta_link);
 354         if (pendp != NULL)
 355                 *pendp = task->ta_pending;
 356         task->ta_pending = 0;
 357         return (task == queue->tq_running ? EBUSY : 0);
 358 }
 359
 360 int
 361 taskqueue_cancel(struct taskqueue *queue, struct task *task, u_int *pendp)
 362 {
 363         int error;
 364
 365         TQ_LOCK(queue);
 366         error = taskqueue_cancel_locked(queue, task, pendp);
 367         TQ_UNLOCK(queue);
 368
 369         return (error);
 370 }
 371
 372 int
 373 taskqueue_cancel_timeout(struct taskqueue *queue,
 374                          struct timeout_task *timeout_task, u_int *pendp)
 375 {
 376         u_int pending, pending1;
 377         int error;
 378
 379         pending = !!callout_stop(&timeout_task->c);
 380         TQ_LOCK(queue);
 381         error = taskqueue_cancel_locked(queue, &timeout_task->t, &pending1);
 382         if ((timeout_task->f & DT_CALLOUT_ARMED) != 0) {
 383                 timeout_task->f &= ~DT_CALLOUT_ARMED;
 384                 queue->tq_callouts--;
 385         }
 386         TQ_UNLOCK(queue);
 387
 388         if (pendp != NULL)
 389                 *pendp = pending + pending1;
 390         return (error);
 391 }
 392
 393 void
 394 taskqueue_drain(struct taskqueue *queue, struct task *task)
 395 {
 396         TQ_LOCK(queue);
 397         while (task->ta_pending != 0 || task == queue->tq_running)
 398                 TQ_SLEEP(queue, task, "-");
 399         TQ_UNLOCK(queue);
 400 }
 401
 402 void
 403 taskqueue_drain_timeout(struct taskqueue *queue,
 404     struct timeout_task *timeout_task)
 405 {
 406
 407         callout_stop_sync(&timeout_task->c);
 408         taskqueue_drain(queue, &timeout_task->t);
 409 }
 410
 411 static void
 412 taskqueue_swi_enqueue(void *context)
 413 {
 414         setsofttq();
 415 }
 416
 417 static void
 418 taskqueue_swi_run(void *arg, void *frame)
 419 {
 420         taskqueue_run(taskqueue_swi, 0);
 421 }
 422
 423 static void
 424 taskqueue_swi_mp_run(void *arg, void *frame)
 425 {
 426         taskqueue_run(taskqueue_swi_mp, 0);
 427 }
 428
 429 int
 430 taskqueue_start_threads(struct taskqueue **tqp, int count, int pri, int ncpu,
 431                         const char *fmt, ...)
 432 {
 433         __va_list ap;
 434         struct thread *td;
 435         struct taskqueue *tq;
 436         int i, error, cpu;
 437         char ktname[MAXCOMLEN];
 438
 439         if (count <= 0)
 440                 return EINVAL;
 441         /* catch call argument mistakes */
 442         KKASSERT(pri > 0 && pri < TDPRI_MAX);
 443
 444         tq = *tqp;
 445         cpu = ncpu;
 446
 447         __va_start(ap, fmt);
 448         kvsnprintf(ktname, MAXCOMLEN, fmt, ap);
 449         __va_end(ap);
 450
 451         tq->tq_threads = kmalloc(sizeof(struct thread *) * count, M_TASKQUEUE,
 452             M_WAITOK | M_ZERO);
 453
 454         for (i = 0; i < count; i++) {
 455                 /*
 456                  * If no specific cpu was specified and more than one thread
 457                  * is to be created, we distribute the threads amongst all
 458                  * cpus.
 459                  */
 460                 if ((ncpu <= -1) && (count > 1))
 461                         cpu = i%ncpus;
 462
 463                 if (count == 1) {
 464                         error = lwkt_create(taskqueue_thread_loop, tqp,
 465                                             &tq->tq_threads[i], NULL,
 466                                             TDF_NOSTART, cpu,
 467                                             "%s", ktname);
 468                 } else {
 469                         error = lwkt_create(taskqueue_thread_loop, tqp,
 470                                             &tq->tq_threads[i], NULL,
 471                                             TDF_NOSTART, cpu,
 472                                             "%s_%d", ktname, i);
 473                 }
 474                 if (error) {
 475                         kprintf("%s: lwkt_create(%s): error %d", __func__,
 476                             ktname, error);
 477                         tq->tq_threads[i] = NULL;
 478                 } else {
 479                         td = tq->tq_threads[i];
 480                         lwkt_setpri_initial(td, pri);
 481                         lwkt_schedule(td);
 482                         tq->tq_tcount++;
 483                 }
 484         }
 485
 486         return 0;
 487 }
 488
 489 void
 490 taskqueue_thread_loop(void *arg)
 491 {
 492         struct taskqueue **tqp, *tq;
 493
 494         tqp = arg;
 495         tq = *tqp;
 496         TQ_LOCK(tq);
 497         while ((tq->tq_flags & TQ_FLAGS_ACTIVE) != 0) {
 498                 taskqueue_run(tq, 1);
 499                 TQ_SLEEP(tq, tq, "tqthr");
 500         }
 501
 502         /* rendezvous with thread that asked us to terminate */
 503         tq->tq_tcount--;
 504         TQ_UNLOCK(tq);
 505         wakeup_one(tq->tq_threads);
 506         lwkt_exit();
 507 }
 508
 509 /* NOTE: tq must be locked */
 510 void
 511 taskqueue_thread_enqueue(void *context)
 512 {
 513         struct taskqueue **tqp, *tq;
 514
 515         tqp = context;
 516         tq = *tqp;
 517
 518         /* Unlock spinlock before wakeup_one() */
 519         TQ_UNLOCK(tq);
 520         wakeup_one(tq);
 521         TQ_LOCK(tq);
 522 }
 523
 524 TASKQUEUE_DEFINE(swi, taskqueue_swi_enqueue, 0,
 525          register_swi(SWI_TQ, taskqueue_swi_run, NULL, "swi_taskq", NULL, -1));
 526 /*
 527  * XXX: possibly use a different SWI_TQ_MP or so.
 528  * related: sys/interrupt.h
 529  * related: platform/XXX/isa/ipl_funcs.c
 530  */
 531 TASKQUEUE_DEFINE(swi_mp, taskqueue_swi_enqueue, 0,
 532     register_swi_mp(SWI_TQ, taskqueue_swi_mp_run, NULL, "swi_mp_taskq", NULL,
 533                     -1));
 534
 535 struct taskqueue *taskqueue_thread[MAXCPU];
 536
 537 static void
 538 taskqueue_init(void)
 539 {
 540         int cpu;
 541
 542         lockinit(&taskqueue_queues_lock, "tqqueues", 0, 0);
 543         STAILQ_INIT(&taskqueue_queues);
 544
 545         for (cpu = 0; cpu < ncpus; cpu++) {
 546                 taskqueue_thread[cpu] = taskqueue_create("thread", M_INTWAIT,
 547                     taskqueue_thread_enqueue, &taskqueue_thread[cpu]);
 548                 taskqueue_start_threads(&taskqueue_thread[cpu], 1,
 549                     TDPRI_KERN_DAEMON, cpu, "taskq_cpu %d", cpu);
 550         }
 551 }
 552
 553 SYSINIT(taskqueueinit, SI_SUB_PRE_DRIVERS, SI_ORDER_ANY, taskqueue_init, NULL);