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 void
 206 taskqueue_block(struct taskqueue *queue)
 207 {
 208
 209         TQ_LOCK(queue);
 210         queue->tq_flags |= TQ_FLAGS_BLOCKED;
 211         TQ_UNLOCK(queue);
 212 }
 213
 214 void
 215 taskqueue_unblock(struct taskqueue *queue)
 216 {
 217
 218         TQ_LOCK(queue);
 219         queue->tq_flags &= ~TQ_FLAGS_BLOCKED;
 220         if (queue->tq_flags & TQ_FLAGS_PENDING) {
 221                 queue->tq_flags &= ~TQ_FLAGS_PENDING;
 222                 queue->tq_enqueue(queue->tq_context);
 223         }
 224         TQ_UNLOCK(queue);
 225 }
 226
 227 static void
 228 taskqueue_run_locked(struct taskqueue *queue)
 229 {
 230         struct taskqueue_busy tb;
 231         struct task *task;
 232         int pending;
 233
 234         mtx_assert(&queue->tq_mutex, MA_OWNED);
 235         tb.tb_running = NULL;
 236         TAILQ_INSERT_TAIL(&queue->tq_active, &tb, tb_link);
 237
 238         while (STAILQ_FIRST(&queue->tq_queue)) {
 239                 /*
 240                  * Carefully remove the first task from the queue and
 241                  * zero its pending count.
 242                  */
 243                 task = STAILQ_FIRST(&queue->tq_queue);
 244                 STAILQ_REMOVE_HEAD(&queue->tq_queue, ta_link);
 245                 pending = task->ta_pending;
 246                 task->ta_pending = 0;
 247                 tb.tb_running = task;
 248                 TQ_UNLOCK(queue);
 249
 250                 task->ta_func(task->ta_context, pending);
 251
 252                 TQ_LOCK(queue);
 253                 tb.tb_running = NULL;
 254                 wakeup(task);
 255         }
 256         TAILQ_REMOVE(&queue->tq_active, &tb, tb_link);
 257 }
 258
 259 void
 260 taskqueue_run(struct taskqueue *queue)
 261 {
 262
 263         TQ_LOCK(queue);
 264         taskqueue_run_locked(queue);
 265         TQ_UNLOCK(queue);
 266 }
 267
 268 static int
 269 task_is_running(struct taskqueue *queue, struct task *task)
 270 {
 271         struct taskqueue_busy *tb;
 272
 273         mtx_assert(&queue->tq_mutex, MA_OWNED);
 274         TAILQ_FOREACH(tb, &queue->tq_active, tb_link) {
 275                 if (tb->tb_running == task)
 276                         return (1);
 277         }
 278         return (0);
 279 }
 280
 281 void
 282 taskqueue_drain(struct taskqueue *queue, struct task *task)
 283 {
 284         if (queue->tq_spin) {           /* XXX */
 285                 mtx_lock_spin(&queue->tq_mutex);
 286                 while (task->ta_pending != 0 || task_is_running(queue, task))
 287                         msleep_spin(task, &queue->tq_mutex, "-", 0);
 288                 mtx_unlock_spin(&queue->tq_mutex);
 289         } else {
 290                 WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, NULL, __func__);
 291
 292                 mtx_lock(&queue->tq_mutex);
 293                 while (task->ta_pending != 0 || task_is_running(queue, task))
 294                         msleep(task, &queue->tq_mutex, PWAIT, "-", 0);
 295                 mtx_unlock(&queue->tq_mutex);
 296         }
 297 }
 298
 299 static void
 300 taskqueue_swi_enqueue(void *context)
 301 {
 302         swi_sched(taskqueue_ih, 0);
 303 }
 304
 305 static void
 306 taskqueue_swi_run(void *dummy)
 307 {
 308         taskqueue_run(taskqueue_swi);
 309 }
 310
 311 static void
 312 taskqueue_swi_giant_enqueue(void *context)
 313 {
 314         swi_sched(taskqueue_giant_ih, 0);
 315 }
 316
 317 static void
 318 taskqueue_swi_giant_run(void *dummy)
 319 {
 320         taskqueue_run(taskqueue_swi_giant);
 321 }
 322
 323 int
 324 taskqueue_start_threads(struct taskqueue **tqp, int count, int pri,
 325                         const char *name, ...)
 326 {
 327         va_list ap;
 328         struct thread *td;
 329         struct taskqueue *tq;
 330         int i, error;
 331         char ktname[MAXCOMLEN + 1];
 332
 333         if (count <= 0)
 334                 return (EINVAL);
 335
 336         tq = *tqp;
 337
 338         va_start(ap, name);
 339         vsnprintf(ktname, sizeof(ktname), name, ap);
 340         va_end(ap);
 341
 342         tq->tq_threads = malloc(sizeof(struct thread *) * count, M_TASKQUEUE,
 343             M_NOWAIT | M_ZERO);
 344         if (tq->tq_threads == NULL) {
 345                 printf("%s: no memory for %s threads\n", __func__, ktname);
 346                 return (ENOMEM);
 347         }
 348
 349         for (i = 0; i < count; i++) {
 350                 if (count == 1)
 351                         error = kthread_add(taskqueue_thread_loop, tqp, NULL,
 352                             &tq->tq_threads[i], RFSTOPPED, 0, "%s", ktname);
 353                 else
 354                         error = kthread_add(taskqueue_thread_loop, tqp, NULL,
 355                             &tq->tq_threads[i], RFSTOPPED, 0,
 356                             "%s_%d", ktname, i);
 357                 if (error) {
 358                         /* should be ok to continue, taskqueue_free will dtrt */
 359                         printf("%s: kthread_add(%s): error %d", __func__,
 360                             ktname, error);
 361                         tq->tq_threads[i] = NULL;               /* paranoid */
 362                 } else
 363                         tq->tq_tcount++;
 364         }
 365         for (i = 0; i < count; i++) {
 366                 if (tq->tq_threads[i] == NULL)
 367                         continue;
 368                 td = tq->tq_threads[i];
 369                 thread_lock(td);
 370                 sched_prio(td, pri);
 371                 sched_add(td, SRQ_BORING);
 372                 thread_unlock(td);
 373         }
 374
 375         return (0);
 376 }
 377
 378 void
 379 taskqueue_thread_loop(void *arg)
 380 {
 381         struct taskqueue **tqp, *tq;
 382
 383         tqp = arg;
 384         tq = *tqp;
 385         TQ_LOCK(tq);
 386         while ((tq->tq_flags & TQ_FLAGS_ACTIVE) != 0) {
 387                 taskqueue_run_locked(tq);
 388                 /*
 389                  * Because taskqueue_run() can drop tq_mutex, we need to
 390                  * check if the TQ_FLAGS_ACTIVE flag wasn't removed in the
 391                  * meantime, which means we missed a wakeup.
 392                  */
 393                 if ((tq->tq_flags & TQ_FLAGS_ACTIVE) == 0)
 394                         break;
 395                 TQ_SLEEP(tq, tq, &tq->tq_mutex, 0, "-", 0);
 396         }
 397
 398         /* rendezvous with thread that asked us to terminate */
 399         tq->tq_tcount--;
 400         wakeup_one(tq->tq_threads);
 401         TQ_UNLOCK(tq);
 402         kthread_exit();
 403 }
 404
 405 void
 406 taskqueue_thread_enqueue(void *context)
 407 {
 408         struct taskqueue **tqp, *tq;
 409
 410         tqp = context;
 411         tq = *tqp;
 412
 413         mtx_assert(&tq->tq_mutex, MA_OWNED);
 414         wakeup_one(tq);
 415 }
 416
 417 TASKQUEUE_DEFINE(swi, taskqueue_swi_enqueue, NULL,
 418                  swi_add(NULL, "task queue", taskqueue_swi_run, NULL, SWI_TQ,
 419                      INTR_MPSAFE, &taskqueue_ih));
 420
 421 TASKQUEUE_DEFINE(swi_giant, taskqueue_swi_giant_enqueue, NULL,
 422                  swi_add(NULL, "Giant taskq", taskqueue_swi_giant_run,
 423                      NULL, SWI_TQ_GIANT, 0, &taskqueue_giant_ih));
 424
 425 TASKQUEUE_DEFINE_THREAD(thread);
 426
 427 struct taskqueue *
 428 taskqueue_create_fast(const char *name, int mflags,
 429                  taskqueue_enqueue_fn enqueue, void *context)
 430 {
 431         return _taskqueue_create(name, mflags, enqueue, context,
 432                         MTX_SPIN, "fast_taskqueue");
 433 }
 434
 435 /* NB: for backwards compatibility */
 436 int
 437 taskqueue_enqueue_fast(struct taskqueue *queue, struct task *task)
 438 {
 439         return taskqueue_enqueue(queue, task);
 440 }
 441
 442 static void     *taskqueue_fast_ih;
 443
 444 static void
 445 taskqueue_fast_enqueue(void *context)
 446 {
 447         swi_sched(taskqueue_fast_ih, 0);
 448 }
 449
 450 static void
 451 taskqueue_fast_run(void *dummy)
 452 {
 453         taskqueue_run(taskqueue_fast);
 454 }
 455
 456 TASKQUEUE_FAST_DEFINE(fast, taskqueue_fast_enqueue, NULL,
 457         swi_add(NULL, "fast taskq", taskqueue_fast_run, NULL,
 458         SWI_TQ_FAST, INTR_MPSAFE, &taskqueue_fast_ih));
 459
 460 int
 461 taskqueue_member(struct taskqueue *queue, struct thread *td)
 462 {
 463         int i, j, ret = 0;
 464
 465         TQ_LOCK(queue);
 466         for (i = 0, j = 0; ; i++) {
 467                 if (queue->tq_threads[i] == NULL)
 468                         continue;
 469                 if (queue->tq_threads[i] == td) {
 470                         ret = 1;
 471                         break;
 472                 }
 473                 if (++j >= queue->tq_tcount)
 474                         break;
 475         }
 476         TQ_UNLOCK(queue);
 477         return (ret);
 478 }