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