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