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
  27 #include <sys/cdefs.h>
  28 __FBSDID("$FreeBSD$");
  29
  30 #include <sys/param.h>
  31 #include <sys/systm.h>
  32 #include <sys/bus.h>
  33 #include <sys/interrupt.h>
  34 #include <sys/kernel.h>
  35 #include <sys/kthread.h>
  36 #include <sys/limits.h>
  37 #include <sys/lock.h>
  38 #include <sys/malloc.h>
  39 #include <sys/mutex.h>
  40 #include <sys/proc.h>
  41 #include <sys/sched.h>
  42 #include <sys/taskqueue.h>
  43 #include <sys/unistd.h>
  44 #include <machine/stdarg.h>
  45
  46 static MALLOC_DEFINE(M_TASKQUEUE, "taskqueue", "Task Queues");
  47 static void     *taskqueue_giant_ih;
  48 static void     *taskqueue_ih;
  49
  50 struct taskqueue_busy {
  51         struct task     *tb_running;
  52         TAILQ_ENTRY(taskqueue_busy) tb_link;
  53 };
  54
  55 struct taskqueue {
  56         STAILQ_HEAD(, task)     tq_queue;
  57         taskqueue_enqueue_fn    tq_enqueue;
  58         void                    *tq_context;
  59         TAILQ_HEAD(, taskqueue_busy) tq_active;
  60         struct mtx              tq_mutex;
  61         struct thread           **tq_threads;
  62         int                     tq_tcount;
  63         int                     tq_spin;
  64         int                     tq_flags;
  65 };
  66
  67 #define TQ_FLAGS_ACTIVE         (1 << 0)
  68 #define TQ_FLAGS_BLOCKED        (1 << 1)
  69 #define TQ_FLAGS_PENDING        (1 << 2)
  70
  71 static void     taskqueue_run_locked(struct taskqueue *);
  72
  73 static __inline void
  74 TQ_LOCK(struct taskqueue *tq)
  75 {
  76         if (tq->tq_spin)
  77                 mtx_lock_spin(&tq->tq_mutex);
  78         else
  79                 mtx_lock(&tq->tq_mutex);
  80 }
  81
  82 static __inline void
  83 TQ_UNLOCK(struct taskqueue *tq)
  84 {
  85         if (tq->tq_spin)
  86                 mtx_unlock_spin(&tq->tq_mutex);
  87         else
  88                 mtx_unlock(&tq->tq_mutex);
  89 }
  90
  91 static __inline int
  92 TQ_SLEEP(struct taskqueue *tq, void *p, struct mtx *m, int pri, const char *wm,
  93     int t)
  94 {
  95         if (tq->tq_spin)
  96                 return (msleep_spin(p, m, wm, t));
  97         return (msleep(p, m, pri, wm, t));
  98 }
  99
 100 static struct taskqueue *
 101 _taskqueue_create(const char *name __unused, int mflags,
 102                  taskqueue_enqueue_fn enqueue, void *context,
 103                  int mtxflags, const char *mtxname)
 104 {
 105         struct taskqueue *queue;
 106
 107         queue = malloc(sizeof(struct taskqueue), M_TASKQUEUE, mflags | M_ZERO);
 108         if (!queue)
 109                 return NULL;
 110
 111         STAILQ_INIT(&queue->tq_queue);
 112         TAILQ_INIT(&queue->tq_active);
 113         queue->tq_enqueue = enqueue;
 114         queue->tq_context = context;
 115         queue->tq_spin = (mtxflags & MTX_SPIN) != 0;
 116         queue->tq_flags |= TQ_FLAGS_ACTIVE;
 117         mtx_init(&queue->tq_mutex, mtxname, NULL, mtxflags);
 118
 119         return queue;
 120 }
 121
 122 struct taskqueue *
 123 taskqueue_create(const char *name, int mflags,
 124                  taskqueue_enqueue_fn enqueue, void *context)
 125 {
 126         return _taskqueue_create(name, mflags, enqueue, context,
 127                         MTX_DEF, "taskqueue");
 128 }
 129
 130 /*
 131  * Signal a taskqueue thread to terminate.
 132  */
 133 static void
 134 taskqueue_terminate(struct thread **pp, struct taskqueue *tq)
 135 {
 136
 137         while (tq->tq_tcount > 0) {
 138                 wakeup(tq);
 139                 TQ_SLEEP(tq, pp, &tq->tq_mutex, PWAIT, "taskqueue_destroy", 0);
 140         }
 141 }
 142
 143 void
 144 taskqueue_free(struct taskqueue *queue)
 145 {
 146
 147         TQ_LOCK(queue);
 148         queue->tq_flags &= ~TQ_FLAGS_ACTIVE;
 149         taskqueue_run_locked(queue);
 150         taskqueue_terminate(queue->tq_threads, queue);
 151         KASSERT(TAILQ_EMPTY(&queue->tq_active), ("Tasks still running?"));
 152         mtx_destroy(&queue->tq_mutex);
 153         free(queue->tq_threads, M_TASKQUEUE);
 154         free(queue, M_TASKQUEUE);
 155 }
 156
 157 int
 158 taskqueue_enqueue(struct taskqueue *queue, struct task *task)
 159 {
 160         struct task *ins;
 161         struct task *prev;
 162
 163         TQ_LOCK(queue);
 164
 165         /*
 166          * Count multiple enqueues.
 167          */
 168         if (task->ta_pending) {
 169                 if (task->ta_pending < USHRT_MAX)
 170                         task->ta_pending++;
 171                 TQ_UNLOCK(queue);
 172                 return 0;
 173         }
 174
 175         /*
 176          * Optimise the case when all tasks have the same priority.
 177          */
 178         prev = STAILQ_LAST(&queue->tq_queue, task, ta_link);
 179         if (!prev || prev->ta_priority >= task->ta_priority) {
 180                 STAILQ_INSERT_TAIL(&queue->tq_queue, task, ta_link);
 181         } else {
 182                 prev = NULL;
 183                 for (ins = STAILQ_FIRST(&queue->tq_queue); ins;
 184                      prev = ins, ins = STAILQ_NEXT(ins, ta_link))
 185                         if (ins->ta_priority < task->ta_priority)
 186                                 break;
 187
 188                 if (prev)
 189                         STAILQ_INSERT_AFTER(&queue->tq_queue, prev, task, ta_link);
 190                 else
 191                         STAILQ_INSERT_HEAD(&queue->tq_queue, task, ta_link);
 192         }
 193
 194         task->ta_pending = 1;
 195         if ((queue->tq_flags & TQ_FLAGS_BLOCKED) == 0)
 196                 queue->tq_enqueue(queue->tq_context);
 197         else
 198                 queue->tq_flags |= TQ_FLAGS_PENDING;
 199
 200         TQ_UNLOCK(queue);
 201
 202         return 0;
 203 }
 204
 205 static void
 206 taskqueue_drain_running(struct taskqueue *queue)
 207 {
 208
 209         while (!TAILQ_EMPTY(&queue->tq_active))
 210                 TQ_SLEEP(queue, &queue->tq_active, &queue->tq_mutex,
 211                     PWAIT, "-", 0);
 212 }
 213
 214 void
 215 taskqueue_block(struct taskqueue *queue)
 216 {
 217
 218         TQ_LOCK(queue);
 219         queue->tq_flags |= TQ_FLAGS_BLOCKED;
 220         TQ_UNLOCK(queue);
 221 }
 222
 223 void
 224 taskqueue_unblock(struct taskqueue *queue)
 225 {
 226
 227         TQ_LOCK(queue);
 228         queue->tq_flags &= ~TQ_FLAGS_BLOCKED;
 229         if (queue->tq_flags & TQ_FLAGS_PENDING) {
 230                 queue->tq_flags &= ~TQ_FLAGS_PENDING;
 231                 queue->tq_enqueue(queue->tq_context);
 232         }
 233         TQ_UNLOCK(queue);
 234 }
 235
 236 static void
 237 taskqueue_run_locked(struct taskqueue *queue)
 238 {
 239         struct taskqueue_busy tb;
 240         struct task *task;
 241         int pending;
 242
 243         mtx_assert(&queue->tq_mutex, MA_OWNED);
 244         tb.tb_running = NULL;
 245         TAILQ_INSERT_TAIL(&queue->tq_active, &tb, tb_link);
 246
 247         while (STAILQ_FIRST(&queue->tq_queue)) {
 248                 /*
 249                  * Carefully remove the first task from the queue and
 250                  * zero its pending count.
 251                  */
 252                 task = STAILQ_FIRST(&queue->tq_queue);
 253                 STAILQ_REMOVE_HEAD(&queue->tq_queue, ta_link);
 254                 pending = task->ta_pending;
 255                 task->ta_pending = 0;
 256                 tb.tb_running = task;
 257                 TQ_UNLOCK(queue);
 258
 259                 task->ta_func(task->ta_context, pending);
 260
 261                 TQ_LOCK(queue);
 262                 tb.tb_running = NULL;
 263                 wakeup(task);
 264         }
 265         TAILQ_REMOVE(&queue->tq_active, &tb, tb_link);
 266         if (TAILQ_EMPTY(&queue->tq_active))
 267                 wakeup(&queue->tq_active);
 268 }
 269
 270 void
 271 taskqueue_run(struct taskqueue *queue)
 272 {
 273
 274         TQ_LOCK(queue);
 275         taskqueue_run_locked(queue);
 276         TQ_UNLOCK(queue);
 277 }
 278
 279 static int
 280 task_is_running(struct taskqueue *queue, struct task *task)
 281 {
 282         struct taskqueue_busy *tb;
 283
 284         mtx_assert(&queue->tq_mutex, MA_OWNED);
 285         TAILQ_FOREACH(tb, &queue->tq_active, tb_link) {
 286                 if (tb->tb_running == task)
 287                         return (1);
 288         }
 289         return (0);
 290 }
 291
 292 void
 293 taskqueue_drain(struct taskqueue *queue, struct task *task)
 294 {
 295         if (queue->tq_spin) {           /* XXX */
 296                 mtx_lock_spin(&queue->tq_mutex);
 297                 while (task->ta_pending != 0 || task_is_running(queue, task))
 298                         msleep_spin(task, &queue->tq_mutex, "-", 0);
 299                 mtx_unlock_spin(&queue->tq_mutex);
 300         } else {
 301                 WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, NULL, __func__);
 302
 303                 mtx_lock(&queue->tq_mutex);
 304                 while (task->ta_pending != 0 || task_is_running(queue, task))
 305                         msleep(task, &queue->tq_mutex, PWAIT, "-", 0);
 306                 mtx_unlock(&queue->tq_mutex);
 307         }
 308 }
 309
 310 void
 311 taskqueue_drain_all(struct taskqueue *queue)
 312 {
 313         struct task *task;
 314
 315         if (!queue->tq_spin)
 316                 WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, NULL, __func__);
 317
 318         TQ_LOCK(queue);
 319         task = STAILQ_LAST(&queue->tq_queue, task, ta_link);
 320         if (task != NULL)
 321                 while (task->ta_pending != 0)
 322                         TQ_SLEEP(queue, task, &queue->tq_mutex, PWAIT, "-", 0);
 323         taskqueue_drain_running(queue);
 324         KASSERT(STAILQ_EMPTY(&queue->tq_queue),
 325             ("taskqueue queue is not empty after draining"));
 326         TQ_UNLOCK(queue);
 327 }
 328
 329 static void
 330 taskqueue_swi_enqueue(void *context)
 331 {
 332         swi_sched(taskqueue_ih, 0);
 333 }
 334
 335 static void
 336 taskqueue_swi_run(void *dummy)
 337 {
 338         taskqueue_run(taskqueue_swi);
 339 }
 340
 341 static void
 342 taskqueue_swi_giant_enqueue(void *context)
 343 {
 344         swi_sched(taskqueue_giant_ih, 0);
 345 }
 346
 347 static void
 348 taskqueue_swi_giant_run(void *dummy)
 349 {
 350         taskqueue_run(taskqueue_swi_giant);
 351 }
 352
 353 int
 354 taskqueue_start_threads(struct taskqueue **tqp, int count, int pri,
 355                         const char *name, ...)
 356 {
 357         va_list ap;
 358         struct thread *td;
 359         struct taskqueue *tq;
 360         int i, error;
 361         char ktname[MAXCOMLEN + 1];
 362
 363         if (count <= 0)
 364                 return (EINVAL);
 365
 366         tq = *tqp;
 367
 368         va_start(ap, name);
 369         vsnprintf(ktname, sizeof(ktname), name, ap);
 370         va_end(ap);
 371
 372         tq->tq_threads = malloc(sizeof(struct thread *) * count, M_TASKQUEUE,
 373             M_NOWAIT | M_ZERO);
 374         if (tq->tq_threads == NULL) {
 375                 printf("%s: no memory for %s threads\n", __func__, ktname);
 376                 return (ENOMEM);
 377         }
 378
 379         for (i = 0; i < count; i++) {
 380                 if (count == 1)
 381                         error = kthread_add(taskqueue_thread_loop, tqp, NULL,
 382                             &tq->tq_threads[i], RFSTOPPED, 0, "%s", ktname);
 383                 else
 384                         error = kthread_add(taskqueue_thread_loop, tqp, NULL,
 385                             &tq->tq_threads[i], RFSTOPPED, 0,
 386                             "%s_%d", ktname, i);
 387                 if (error) {
 388                         /* should be ok to continue, taskqueue_free will dtrt */
 389                         printf("%s: kthread_add(%s): error %d", __func__,
 390                             ktname, error);
 391                         tq->tq_threads[i] = NULL;               /* paranoid */
 392                 } else
 393                         tq->tq_tcount++;
 394         }
 395         for (i = 0; i < count; i++) {
 396                 if (tq->tq_threads[i] == NULL)
 397                         continue;
 398                 td = tq->tq_threads[i];
 399                 thread_lock(td);
 400                 sched_prio(td, pri);
 401                 sched_add(td, SRQ_BORING);
 402                 thread_unlock(td);
 403         }
 404
 405         return (0);
 406 }
 407
 408 void
 409 taskqueue_thread_loop(void *arg)
 410 {
 411         struct taskqueue **tqp, *tq;
 412
 413         tqp = arg;
 414         tq = *tqp;
 415         TQ_LOCK(tq);
 416         while ((tq->tq_flags & TQ_FLAGS_ACTIVE) != 0) {
 417                 taskqueue_run_locked(tq);
 418                 /*
 419                  * Because taskqueue_run() can drop tq_mutex, we need to
 420                  * check if the TQ_FLAGS_ACTIVE flag wasn't removed in the
 421                  * meantime, which means we missed a wakeup.
 422                  */
 423                 if ((tq->tq_flags & TQ_FLAGS_ACTIVE) == 0)
 424                         break;
 425                 TQ_SLEEP(tq, tq, &tq->tq_mutex, 0, "-", 0);
 426         }
 427
 428         /* rendezvous with thread that asked us to terminate */
 429         tq->tq_tcount--;
 430         wakeup_one(tq->tq_threads);
 431         TQ_UNLOCK(tq);
 432         kthread_exit();
 433 }
 434
 435 void
 436 taskqueue_thread_enqueue(void *context)
 437 {
 438         struct taskqueue **tqp, *tq;
 439
 440         tqp = context;
 441         tq = *tqp;
 442
 443         mtx_assert(&tq->tq_mutex, MA_OWNED);
 444         wakeup_one(tq);
 445 }
 446
 447 TASKQUEUE_DEFINE(swi, taskqueue_swi_enqueue, NULL,
 448                  swi_add(NULL, "task queue", taskqueue_swi_run, NULL, SWI_TQ,
 449                      INTR_MPSAFE, &taskqueue_ih));
 450
 451 TASKQUEUE_DEFINE(swi_giant, taskqueue_swi_giant_enqueue, NULL,
 452                  swi_add(NULL, "Giant taskq", taskqueue_swi_giant_run,
 453                      NULL, SWI_TQ_GIANT, 0, &taskqueue_giant_ih));
 454
 455 TASKQUEUE_DEFINE_THREAD(thread);
 456
 457 struct taskqueue *
 458 taskqueue_create_fast(const char *name, int mflags,
 459                  taskqueue_enqueue_fn enqueue, void *context)
 460 {
 461         return _taskqueue_create(name, mflags, enqueue, context,
 462                         MTX_SPIN, "fast_taskqueue");
 463 }
 464
 465 /* NB: for backwards compatibility */
 466 int
 467 taskqueue_enqueue_fast(struct taskqueue *queue, struct task *task)
 468 {
 469         return taskqueue_enqueue(queue, task);
 470 }
 471
 472 static void     *taskqueue_fast_ih;
 473
 474 static void
 475 taskqueue_fast_enqueue(void *context)
 476 {
 477         swi_sched(taskqueue_fast_ih, 0);
 478 }
 479
 480 static void
 481 taskqueue_fast_run(void *dummy)
 482 {
 483         taskqueue_run(taskqueue_fast);
 484 }
 485
 486 TASKQUEUE_FAST_DEFINE(fast, taskqueue_fast_enqueue, NULL,
 487         swi_add(NULL, "fast taskq", taskqueue_fast_run, NULL,
 488         SWI_TQ_FAST, INTR_MPSAFE, &taskqueue_fast_ih));
 489
 490 int
 491 taskqueue_member(struct taskqueue *queue, struct thread *td)
 492 {
 493         int i, j, ret = 0;
 494
 495         TQ_LOCK(queue);
 496         for (i = 0, j = 0; ; i++) {
 497                 if (queue->tq_threads[i] == NULL)
 498                         continue;
 499                 if (queue->tq_threads[i] == td) {
 500                         ret = 1;
 501                         break;
 502                 }
 503                 if (++j >= queue->tq_tcount)
 504                         break;
 505         }
 506         TQ_UNLOCK(queue);
 507         return (ret);
 508 }