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, "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 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                 TQ_UNLOCK(queue);
 276         } else {
 277                 if ((timeout_task->f & DT_CALLOUT_ARMED) != 0) {
 278                         res++;
 279                 } else {
 280                         queue->tq_callouts++;
 281                         timeout_task->f |= DT_CALLOUT_ARMED;
 282                 }
 283                 TQ_UNLOCK(queue);
 284                 callout_reset(&timeout_task->c, ticks, taskqueue_timeout_func,
 285                               timeout_task);
 286         }
 287         return (res);
 288 }
 289
 290 void
 291 taskqueue_block(struct taskqueue *queue)
 292 {
 293         TQ_LOCK(queue);
 294         queue->tq_flags |= TQ_FLAGS_BLOCKED;
 295         TQ_UNLOCK(queue);
 296 }
 297
 298 void
 299 taskqueue_unblock(struct taskqueue *queue)
 300 {
 301         TQ_LOCK(queue);
 302         queue->tq_flags &= ~TQ_FLAGS_BLOCKED;
 303         if (queue->tq_flags & TQ_FLAGS_PENDING) {
 304                 queue->tq_flags &= ~TQ_FLAGS_PENDING;
 305                 if (queue->tq_enqueue)
 306                         queue->tq_enqueue(queue->tq_context);
 307         }
 308         TQ_UNLOCK(queue);
 309 }
 310
 311 static void
 312 taskqueue_run(struct taskqueue *queue, int lock_held)
 313 {
 314         struct task *task;
 315         int pending;
 316
 317         if (lock_held == 0)
 318                 TQ_LOCK(queue);
 319         while (STAILQ_FIRST(&queue->tq_queue)) {
 320                 /*
 321                  * Carefully remove the first task from the queue and
 322                  * zero its pending count.
 323                  */
 324                 task = STAILQ_FIRST(&queue->tq_queue);
 325                 STAILQ_REMOVE_HEAD(&queue->tq_queue, ta_link);
 326                 pending = task->ta_pending;
 327                 task->ta_pending = 0;
 328                 queue->tq_running = task;
 329
 330                 TQ_UNLOCK(queue);
 331                 task->ta_func(task->ta_context, pending);
 332                 queue->tq_running = NULL;
 333                 wakeup(task);
 334                 TQ_LOCK(queue);
 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         int error;
 357
 358         TQ_LOCK(queue);
 359         error = taskqueue_cancel_locked(queue, task, pendp);
 360         TQ_UNLOCK(queue);
 361
 362         return (error);
 363 }
 364
 365 int
 366 taskqueue_cancel_timeout(struct taskqueue *queue,
 367                          struct timeout_task *timeout_task, u_int *pendp)
 368 {
 369         u_int pending, pending1;
 370         int error;
 371
 372         pending = !!callout_stop(&timeout_task->c);
 373         TQ_LOCK(queue);
 374         error = taskqueue_cancel_locked(queue, &timeout_task->t, &pending1);
 375         if ((timeout_task->f & DT_CALLOUT_ARMED) != 0) {
 376                 timeout_task->f &= ~DT_CALLOUT_ARMED;
 377                 queue->tq_callouts--;
 378         }
 379         TQ_UNLOCK(queue);
 380
 381         if (pendp != NULL)
 382                 *pendp = pending + pending1;
 383         return (error);
 384 }
 385
 386 void
 387 taskqueue_drain(struct taskqueue *queue, struct task *task)
 388 {
 389         TQ_LOCK(queue);
 390         while (task->ta_pending != 0 || task == queue->tq_running)
 391                 TQ_SLEEP(queue, task, "-");
 392         TQ_UNLOCK(queue);
 393 }
 394
 395 void
 396 taskqueue_drain_timeout(struct taskqueue *queue,
 397     struct timeout_task *timeout_task)
 398 {
 399
 400         callout_stop_sync(&timeout_task->c);
 401         taskqueue_drain(queue, &timeout_task->t);
 402 }
 403
 404 static void
 405 taskqueue_swi_enqueue(void *context)
 406 {
 407         setsofttq();
 408 }
 409
 410 static void
 411 taskqueue_swi_run(void *arg, void *frame)
 412 {
 413         taskqueue_run(taskqueue_swi, 0);
 414 }
 415
 416 static void
 417 taskqueue_swi_mp_run(void *arg, void *frame)
 418 {
 419         taskqueue_run(taskqueue_swi_mp, 0);
 420 }
 421
 422 int
 423 taskqueue_start_threads(struct taskqueue **tqp, int count, int pri, int ncpu,
 424                         const char *fmt, ...)
 425 {
 426         __va_list ap;
 427         struct thread *td;
 428         struct taskqueue *tq;
 429         int i, error, cpu;
 430         char ktname[MAXCOMLEN];
 431
 432         if (count <= 0)
 433                 return EINVAL;
 434
 435         tq = *tqp;
 436         cpu = ncpu;
 437
 438         __va_start(ap, fmt);
 439         kvsnprintf(ktname, MAXCOMLEN, fmt, ap);
 440         __va_end(ap);
 441
 442         tq->tq_threads = kmalloc(sizeof(struct thread *) * count, M_TASKQUEUE,
 443             M_WAITOK | M_ZERO);
 444
 445         for (i = 0; i < count; i++) {
 446                 /*
 447                  * If no specific cpu was specified and more than one thread
 448                  * is to be created, we distribute the threads amongst all
 449                  * cpus.
 450                  */
 451                 if ((ncpu <= -1) && (count > 1))
 452                         cpu = i%ncpus;
 453
 454                 if (count == 1) {
 455                         error = lwkt_create(taskqueue_thread_loop, tqp,
 456                                             &tq->tq_threads[i], NULL,
 457                                             TDF_NOSTART, cpu,
 458                                             "%s", ktname);
 459                 } else {
 460                         error = lwkt_create(taskqueue_thread_loop, tqp,
 461                                             &tq->tq_threads[i], NULL,
 462                                             TDF_NOSTART, cpu,
 463                                             "%s_%d", ktname, i);
 464                 }
 465                 if (error) {
 466                         kprintf("%s: lwkt_create(%s): error %d", __func__,
 467                             ktname, error);
 468                         tq->tq_threads[i] = NULL;
 469                 } else {
 470                         td = tq->tq_threads[i];
 471                         lwkt_setpri_initial(td, pri);
 472                         lwkt_schedule(td);
 473                         tq->tq_tcount++;
 474                 }
 475         }
 476
 477         return 0;
 478 }
 479
 480 void
 481 taskqueue_thread_loop(void *arg)
 482 {
 483         struct taskqueue **tqp, *tq;
 484
 485         tqp = arg;
 486         tq = *tqp;
 487         TQ_LOCK(tq);
 488         while ((tq->tq_flags & TQ_FLAGS_ACTIVE) != 0) {
 489                 taskqueue_run(tq, 1);
 490                 TQ_SLEEP(tq, tq, "tqthr");
 491         }
 492
 493         /* rendezvous with thread that asked us to terminate */
 494         tq->tq_tcount--;
 495         TQ_UNLOCK(tq);
 496         wakeup_one(tq->tq_threads);
 497         lwkt_exit();
 498 }
 499
 500 void
 501 taskqueue_thread_enqueue(void *context)
 502 {
 503         struct taskqueue **tqp, *tq;
 504
 505         tqp = context;
 506         tq = *tqp;
 507
 508         wakeup_one(tq);
 509 }
 510
 511 TASKQUEUE_DEFINE(swi, taskqueue_swi_enqueue, 0,
 512          register_swi(SWI_TQ, taskqueue_swi_run, NULL, "swi_taskq", NULL, -1));
 513 /*
 514  * XXX: possibly use a different SWI_TQ_MP or so.
 515  * related: sys/interrupt.h
 516  * related: platform/XXX/isa/ipl_funcs.c
 517  */
 518 TASKQUEUE_DEFINE(swi_mp, taskqueue_swi_enqueue, 0,
 519     register_swi_mp(SWI_TQ, taskqueue_swi_mp_run, NULL, "swi_mp_taskq", NULL,
 520                     -1));
 521
 522 struct taskqueue *taskqueue_thread[MAXCPU];
 523
 524 static void
 525 taskqueue_init(void)
 526 {
 527         int cpu;
 528
 529         lockinit(&taskqueue_queues_lock, "tqqueues", 0, 0);
 530         STAILQ_INIT(&taskqueue_queues);
 531
 532         for (cpu = 0; cpu < ncpus; cpu++) {
 533                 taskqueue_thread[cpu] = taskqueue_create("thread", M_INTWAIT,
 534                     taskqueue_thread_enqueue, &taskqueue_thread[cpu]);
 535                 taskqueue_start_threads(&taskqueue_thread[cpu], 1,
 536                     TDPRI_KERN_DAEMON, cpu, "taskq_cpu %d", cpu);
 537         }
 538 }
 539
 540 SYSINIT(taskqueueinit, SI_SUB_PRE_DRIVERS, SI_ORDER_ANY, taskqueue_init, NULL);