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