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 static STAILQ_HEAD(taskqueue_list, taskqueue) taskqueue_queues;
  49 static struct mtx taskqueue_queues_mutex;
  50
  51 struct taskqueue {
  52         STAILQ_ENTRY(taskqueue) tq_link;
  53         STAILQ_HEAD(, task)     tq_queue;
  54         const char              *tq_name;
  55         taskqueue_enqueue_fn    tq_enqueue;
  56         void                    *tq_context;
  57         struct task             *tq_running;
  58         struct mtx              tq_mutex;
  59         struct thread           **tq_threads;
  60         int                     tq_tcount;
  61         int                     tq_spin;
  62         int                     tq_flags;
  63 };
  64
  65 #define TQ_FLAGS_ACTIVE         (1 << 0)
  66 #define TQ_FLAGS_BLOCKED        (1 << 1)
  67 #define TQ_FLAGS_PENDING        (1 << 2)
  68
  69 static __inline void
  70 TQ_LOCK(struct taskqueue *tq)
  71 {
  72         if (tq->tq_spin)
  73                 mtx_lock_spin(&tq->tq_mutex);
  74         else
  75                 mtx_lock(&tq->tq_mutex);
  76 }
  77
  78 static __inline void
  79 TQ_UNLOCK(struct taskqueue *tq)
  80 {
  81         if (tq->tq_spin)
  82                 mtx_unlock_spin(&tq->tq_mutex);
  83         else
  84                 mtx_unlock(&tq->tq_mutex);
  85 }
  86
  87 static void     init_taskqueue_list(void *data);
  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 void
  99 init_taskqueue_list(void *data __unused)
 100 {
 101
 102         mtx_init(&taskqueue_queues_mutex, "taskqueue list", NULL, MTX_DEF);
 103         STAILQ_INIT(&taskqueue_queues);
 104 }
 105 SYSINIT(taskqueue_list, SI_SUB_INTRINSIC, SI_ORDER_ANY, init_taskqueue_list,
 106     NULL);
 107
 108 static struct taskqueue *
 109 _taskqueue_create(const char *name, int mflags,
 110                  taskqueue_enqueue_fn enqueue, void *context,
 111                  int mtxflags, const char *mtxname)
 112 {
 113         struct taskqueue *queue;
 114
 115         queue = malloc(sizeof(struct taskqueue), M_TASKQUEUE, mflags | M_ZERO);
 116         if (!queue)
 117                 return 0;
 118
 119         STAILQ_INIT(&queue->tq_queue);
 120         queue->tq_name = name;
 121         queue->tq_enqueue = enqueue;
 122         queue->tq_context = context;
 123         queue->tq_spin = (mtxflags & MTX_SPIN) != 0;
 124         queue->tq_flags |= TQ_FLAGS_ACTIVE;
 125         mtx_init(&queue->tq_mutex, mtxname, NULL, mtxflags);
 126
 127         mtx_lock(&taskqueue_queues_mutex);
 128         STAILQ_INSERT_TAIL(&taskqueue_queues, queue, tq_link);
 129         mtx_unlock(&taskqueue_queues_mutex);
 130
 131         return queue;
 132 }
 133
 134 struct taskqueue *
 135 taskqueue_create(const char *name, int mflags,
 136                  taskqueue_enqueue_fn enqueue, void *context)
 137 {
 138         return _taskqueue_create(name, mflags, enqueue, context,
 139                         MTX_DEF, "taskqueue");
 140 }
 141
 142 /*
 143  * Signal a taskqueue thread to terminate.
 144  */
 145 static void
 146 taskqueue_terminate(struct thread **pp, struct taskqueue *tq)
 147 {
 148
 149         while (tq->tq_tcount > 0) {
 150                 wakeup(tq);
 151                 TQ_SLEEP(tq, pp, &tq->tq_mutex, PWAIT, "taskqueue_destroy", 0);
 152         }
 153 }
 154
 155 void
 156 taskqueue_free(struct taskqueue *queue)
 157 {
 158
 159         mtx_lock(&taskqueue_queues_mutex);
 160         STAILQ_REMOVE(&taskqueue_queues, queue, taskqueue, tq_link);
 161         mtx_unlock(&taskqueue_queues_mutex);
 162
 163         TQ_LOCK(queue);
 164         queue->tq_flags &= ~TQ_FLAGS_ACTIVE;
 165         taskqueue_run(queue);
 166         taskqueue_terminate(queue->tq_threads, queue);
 167         mtx_destroy(&queue->tq_mutex);
 168         free(queue->tq_threads, M_TASKQUEUE);
 169         free(queue, M_TASKQUEUE);
 170 }
 171
 172 /*
 173  * Returns with the taskqueue locked.
 174  */
 175 struct taskqueue *
 176 taskqueue_find(const char *name)
 177 {
 178         struct taskqueue *queue;
 179
 180         mtx_lock(&taskqueue_queues_mutex);
 181         STAILQ_FOREACH(queue, &taskqueue_queues, tq_link) {
 182                 if (strcmp(queue->tq_name, name) == 0) {
 183                         TQ_LOCK(queue);
 184                         mtx_unlock(&taskqueue_queues_mutex);
 185                         return queue;
 186                 }
 187         }
 188         mtx_unlock(&taskqueue_queues_mutex);
 189         return NULL;
 190 }
 191
 192 int
 193 taskqueue_enqueue(struct taskqueue *queue, struct task *task)
 194 {
 195         struct task *ins;
 196         struct task *prev;
 197
 198         TQ_LOCK(queue);
 199
 200         /*
 201          * Count multiple enqueues.
 202          */
 203         if (task->ta_pending) {
 204                 task->ta_pending++;
 205                 TQ_UNLOCK(queue);
 206                 return 0;
 207         }
 208
 209         /*
 210          * Optimise the case when all tasks have the same priority.
 211          */
 212         prev = STAILQ_LAST(&queue->tq_queue, task, ta_link);
 213         if (!prev || prev->ta_priority >= task->ta_priority) {
 214                 STAILQ_INSERT_TAIL(&queue->tq_queue, task, ta_link);
 215         } else {
 216                 prev = 0;
 217                 for (ins = STAILQ_FIRST(&queue->tq_queue); ins;
 218                      prev = ins, ins = STAILQ_NEXT(ins, ta_link))
 219                         if (ins->ta_priority < task->ta_priority)
 220                                 break;
 221
 222                 if (prev)
 223                         STAILQ_INSERT_AFTER(&queue->tq_queue, prev, task, ta_link);
 224                 else
 225                         STAILQ_INSERT_HEAD(&queue->tq_queue, task, ta_link);
 226         }
 227
 228         task->ta_pending = 1;
 229         if ((queue->tq_flags & TQ_FLAGS_BLOCKED) == 0)
 230                 queue->tq_enqueue(queue->tq_context);
 231         else
 232                 queue->tq_flags |= TQ_FLAGS_PENDING;
 233
 234         TQ_UNLOCK(queue);
 235
 236         return 0;
 237 }
 238
 239 void
 240 taskqueue_block(struct taskqueue *queue)
 241 {
 242
 243         TQ_LOCK(queue);
 244         queue->tq_flags |= TQ_FLAGS_BLOCKED;
 245         TQ_UNLOCK(queue);
 246 }
 247
 248 void
 249 taskqueue_unblock(struct taskqueue *queue)
 250 {
 251
 252         TQ_LOCK(queue);
 253         queue->tq_flags &= ~TQ_FLAGS_BLOCKED;
 254         if (queue->tq_flags & TQ_FLAGS_PENDING) {
 255                 queue->tq_flags &= ~TQ_FLAGS_PENDING;
 256                 queue->tq_enqueue(queue->tq_context);
 257         }
 258         TQ_UNLOCK(queue);
 259 }
 260
 261 void
 262 taskqueue_run(struct taskqueue *queue)
 263 {
 264         struct task *task;
 265         int owned, pending;
 266
 267         owned = mtx_owned(&queue->tq_mutex);
 268         if (!owned)
 269                 TQ_LOCK(queue);
 270         while (STAILQ_FIRST(&queue->tq_queue)) {
 271                 /*
 272                  * Carefully remove the first task from the queue and
 273                  * zero its pending count.
 274                  */
 275                 task = STAILQ_FIRST(&queue->tq_queue);
 276                 STAILQ_REMOVE_HEAD(&queue->tq_queue, ta_link);
 277                 pending = task->ta_pending;
 278                 task->ta_pending = 0;
 279                 queue->tq_running = task;
 280                 TQ_UNLOCK(queue);
 281
 282                 task->ta_func(task->ta_context, pending);
 283
 284                 TQ_LOCK(queue);
 285                 queue->tq_running = NULL;
 286                 wakeup(task);
 287         }
 288
 289         /*
 290          * For compatibility, unlock on return if the queue was not locked
 291          * on entry, although this opens a race window.
 292          */
 293         if (!owned)
 294                 TQ_UNLOCK(queue);
 295 }
 296
 297 void
 298 taskqueue_drain(struct taskqueue *queue, struct task *task)
 299 {
 300         if (queue->tq_spin) {           /* XXX */
 301                 mtx_lock_spin(&queue->tq_mutex);
 302                 while (task->ta_pending != 0 || task == queue->tq_running)
 303                         msleep_spin(task, &queue->tq_mutex, "-", 0);
 304                 mtx_unlock_spin(&queue->tq_mutex);
 305         } else {
 306                 WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, NULL, __func__);
 307
 308                 mtx_lock(&queue->tq_mutex);
 309                 while (task->ta_pending != 0 || task == queue->tq_running)
 310                         msleep(task, &queue->tq_mutex, PWAIT, "-", 0);
 311                 mtx_unlock(&queue->tq_mutex);
 312         }
 313 }
 314
 315 static void
 316 taskqueue_swi_enqueue(void *context)
 317 {
 318         swi_sched(taskqueue_ih, 0);
 319 }
 320
 321 static void
 322 taskqueue_swi_run(void *dummy)
 323 {
 324         taskqueue_run(taskqueue_swi);
 325 }
 326
 327 static void
 328 taskqueue_swi_giant_enqueue(void *context)
 329 {
 330         swi_sched(taskqueue_giant_ih, 0);
 331 }
 332
 333 static void
 334 taskqueue_swi_giant_run(void *dummy)
 335 {
 336         taskqueue_run(taskqueue_swi_giant);
 337 }
 338
 339 int
 340 taskqueue_start_threads(struct taskqueue **tqp, int count, int pri,
 341                         const char *name, ...)
 342 {
 343         va_list ap;
 344         struct thread *td;
 345         struct taskqueue *tq;
 346         int i, error;
 347         char ktname[MAXCOMLEN];
 348
 349         if (count <= 0)
 350                 return (EINVAL);
 351
 352         tq = *tqp;
 353
 354         va_start(ap, name);
 355         vsnprintf(ktname, MAXCOMLEN, name, ap);
 356         va_end(ap);
 357
 358         tq->tq_threads = malloc(sizeof(struct thread *) * count, M_TASKQUEUE,
 359             M_NOWAIT | M_ZERO);
 360         if (tq->tq_threads == NULL) {
 361                 printf("%s: no memory for %s threads\n", __func__, ktname);
 362                 return (ENOMEM);
 363         }
 364
 365         for (i = 0; i < count; i++) {
 366                 if (count == 1)
 367                         error = kthread_add(taskqueue_thread_loop, tqp, NULL,
 368                             &tq->tq_threads[i], RFSTOPPED, 0, ktname);
 369                 else
 370                         error = kthread_add(taskqueue_thread_loop, tqp, NULL,
 371                             &tq->tq_threads[i], RFSTOPPED, 0,
 372                             "%s_%d", ktname, i);
 373                 if (error) {
 374                         /* should be ok to continue, taskqueue_free will dtrt */
 375                         printf("%s: kthread_add(%s): error %d", __func__,
 376                             ktname, error);
 377                         tq->tq_threads[i] = NULL;               /* paranoid */
 378                 } else
 379                         tq->tq_tcount++;
 380         }
 381         for (i = 0; i < count; i++) {
 382                 if (tq->tq_threads[i] == NULL)
 383                         continue;
 384                 td = tq->tq_threads[i];
 385                 thread_lock(td);
 386                 sched_prio(td, pri);
 387                 sched_add(td, SRQ_BORING);
 388                 thread_unlock(td);
 389         }
 390
 391         return (0);
 392 }
 393
 394 void
 395 taskqueue_thread_loop(void *arg)
 396 {
 397         struct taskqueue **tqp, *tq;
 398
 399         tqp = arg;
 400         tq = *tqp;
 401         TQ_LOCK(tq);
 402         do {
 403                 taskqueue_run(tq);
 404                 TQ_SLEEP(tq, tq, &tq->tq_mutex, 0, "-", 0);
 405         } while ((tq->tq_flags & TQ_FLAGS_ACTIVE) != 0);
 406
 407         /* rendezvous with thread that asked us to terminate */
 408         tq->tq_tcount--;
 409         wakeup_one(tq->tq_threads);
 410         TQ_UNLOCK(tq);
 411         kthread_exit();
 412 }
 413
 414 void
 415 taskqueue_thread_enqueue(void *context)
 416 {
 417         struct taskqueue **tqp, *tq;
 418
 419         tqp = context;
 420         tq = *tqp;
 421
 422         mtx_assert(&tq->tq_mutex, MA_OWNED);
 423         wakeup_one(tq);
 424 }
 425
 426 TASKQUEUE_DEFINE(swi, taskqueue_swi_enqueue, 0,
 427                  swi_add(NULL, "task queue", taskqueue_swi_run, NULL, SWI_TQ,
 428                      INTR_MPSAFE, &taskqueue_ih));
 429
 430 TASKQUEUE_DEFINE(swi_giant, taskqueue_swi_giant_enqueue, 0,
 431                  swi_add(NULL, "Giant taskq", taskqueue_swi_giant_run,
 432                      NULL, SWI_TQ_GIANT, 0, &taskqueue_giant_ih));
 433
 434 TASKQUEUE_DEFINE_THREAD(thread);
 435
 436 struct taskqueue *
 437 taskqueue_create_fast(const char *name, int mflags,
 438                  taskqueue_enqueue_fn enqueue, void *context)
 439 {
 440         return _taskqueue_create(name, mflags, enqueue, context,
 441                         MTX_SPIN, "fast_taskqueue");
 442 }
 443
 444 /* NB: for backwards compatibility */
 445 int
 446 taskqueue_enqueue_fast(struct taskqueue *queue, struct task *task)
 447 {
 448         return taskqueue_enqueue(queue, task);
 449 }
 450
 451 static void     *taskqueue_fast_ih;
 452
 453 static void
 454 taskqueue_fast_enqueue(void *context)
 455 {
 456         swi_sched(taskqueue_fast_ih, 0);
 457 }
 458
 459 static void
 460 taskqueue_fast_run(void *dummy)
 461 {
 462         taskqueue_run(taskqueue_fast);
 463 }
 464
 465 TASKQUEUE_FAST_DEFINE(fast, taskqueue_fast_enqueue, 0,
 466         swi_add(NULL, "Fast task queue", taskqueue_fast_run, NULL,
 467         SWI_TQ_FAST, INTR_MPSAFE, &taskqueue_fast_ih));