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  *       $FreeBSD: src/sys/kern/subr_taskqueue.c,v 1.1.2.3 2003/09/10 00:40:39 ken Exp $
  27  *      $DragonFly: src/sys/kern/subr_taskqueue.c,v 1.13 2008/06/07 11:44:04 mneumann Exp $
  28  */
  29
  30 #include <sys/param.h>
  31 #include <sys/queue.h>
  32 #include <sys/systm.h>
  33 #include <sys/kernel.h>
  34 #include <sys/taskqueue.h>
  35 #include <sys/interrupt.h>
  36 #include <sys/lock.h>
  37 #include <sys/malloc.h>
  38 #include <sys/kthread.h>
  39 #include <sys/thread2.h>
  40 #include <sys/spinlock.h>
  41 #include <sys/spinlock2.h>
  42 #include <sys/serialize.h>
  43 #include <sys/proc.h>
  44 #include <machine/varargs.h>
  45
  46 MALLOC_DEFINE(M_TASKQUEUE, "taskqueue", "Task Queues");
  47
  48 static STAILQ_HEAD(taskqueue_list, taskqueue) taskqueue_queues;
  49 static struct lock      taskqueue_queues_lock;
  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
  58         struct task             *tq_running;
  59         struct spinlock         tq_lock;
  60         struct thread           **tq_threads;
  61         int                     tq_tcount;
  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_INIT(struct taskqueue *tq)
  71 {
  72         spin_init(&tq->tq_lock);
  73 }
  74
  75 static __inline void
  76 TQ_LOCK_UNINIT(struct taskqueue *tq)
  77 {
  78         spin_uninit(&tq->tq_lock);
  79 }
  80
  81 static __inline void
  82 TQ_LOCK(struct taskqueue *tq)
  83 {
  84         spin_lock_wr(&tq->tq_lock);
  85 }
  86
  87 static __inline void
  88 TQ_UNLOCK(struct taskqueue *tq)
  89 {
  90         spin_unlock_wr(&tq->tq_lock);
  91 }
  92
  93 static __inline void
  94 TQ_SLEEP(struct taskqueue *tq, void *ident, const char *wmesg)
  95 {
  96         ssleep(ident, &tq->tq_lock, 0, wmesg, 0);
  97 }
  98
  99 struct taskqueue *
 100 taskqueue_create(const char *name, int mflags,
 101                  taskqueue_enqueue_fn enqueue, void *context)
 102 {
 103         struct taskqueue *queue;
 104
 105         queue = kmalloc(sizeof(*queue), M_TASKQUEUE, mflags | M_ZERO);
 106         if (!queue)
 107                 return NULL;
 108         STAILQ_INIT(&queue->tq_queue);
 109         queue->tq_name = name;
 110         queue->tq_enqueue = enqueue;
 111         queue->tq_context = context;
 112         queue->tq_flags |= TQ_FLAGS_ACTIVE;
 113         TQ_LOCK_INIT(queue);
 114
 115         lockmgr(&taskqueue_queues_lock, LK_EXCLUSIVE);
 116         STAILQ_INSERT_TAIL(&taskqueue_queues, queue, tq_link);
 117         lockmgr(&taskqueue_queues_lock, LK_RELEASE);
 118
 119         return queue;
 120 }
 121
 122 static void
 123 taskqueue_terminate(struct thread **pp, struct taskqueue *tq)
 124 {
 125         while(tq->tq_tcount > 0) {
 126                 wakeup(tq);
 127                 TQ_SLEEP(tq, pp, "taskqueue_terminate");
 128         }
 129 }
 130
 131 void
 132 taskqueue_free(struct taskqueue *queue)
 133 {
 134         TQ_LOCK(queue);
 135         queue->tq_flags &= ~TQ_FLAGS_ACTIVE;
 136         TQ_UNLOCK(queue);
 137
 138         taskqueue_run(queue);
 139
 140         TQ_LOCK(queue);
 141         taskqueue_terminate(queue->tq_threads, queue);
 142         TQ_UNLOCK(queue);
 143
 144         lockmgr(&taskqueue_queues_lock, LK_EXCLUSIVE);
 145         STAILQ_REMOVE(&taskqueue_queues, queue, taskqueue, tq_link);
 146         lockmgr(&taskqueue_queues_lock, LK_RELEASE);
 147
 148         TQ_LOCK_UNINIT(queue);
 149
 150         kfree(queue, M_TASKQUEUE);
 151 }
 152
 153 struct taskqueue *
 154 taskqueue_find(const char *name)
 155 {
 156         struct taskqueue *queue;
 157
 158         lockmgr(&taskqueue_queues_lock, LK_EXCLUSIVE);
 159         STAILQ_FOREACH(queue, &taskqueue_queues, tq_link) {
 160                 if (!strcmp(queue->tq_name, name)) {
 161                         lockmgr(&taskqueue_queues_lock, LK_RELEASE);
 162                         return queue;
 163                 }
 164         }
 165         lockmgr(&taskqueue_queues_lock, LK_RELEASE);
 166         return NULL;
 167 }
 168
 169 /*
 170  * NOTE!  If using the per-cpu taskqueues ``taskqueue_thread[mycpuid]'',
 171  * be sure NOT TO SHARE the ``task'' between CPUs.  TASKS ARE NOT LOCKED.
 172  * So either use a throwaway task which will only be enqueued once, or
 173  * use one task per CPU!
 174  */
 175 int
 176 taskqueue_enqueue(struct taskqueue *queue, struct task *task)
 177 {
 178         struct task *ins;
 179         struct task *prev;
 180
 181         TQ_LOCK(queue);
 182
 183         /*
 184          * Don't allow new tasks on a queue which is being freed.
 185          */
 186         if ((queue->tq_flags & TQ_FLAGS_ACTIVE) == 0) {
 187                 TQ_UNLOCK(queue);
 188                 return EPIPE;
 189         }
 190
 191         /*
 192          * Count multiple enqueues.
 193          */
 194         if (task->ta_pending) {
 195                 task->ta_pending++;
 196                 TQ_UNLOCK(queue);
 197                 return 0;
 198         }
 199
 200         /*
 201          * Optimise the case when all tasks have the same priority.
 202          */
 203         prev = STAILQ_LAST(&queue->tq_queue, task, ta_link);
 204         if (!prev || prev->ta_priority >= task->ta_priority) {
 205                 STAILQ_INSERT_TAIL(&queue->tq_queue, task, ta_link);
 206         } else {
 207                 prev = NULL;
 208                 for (ins = STAILQ_FIRST(&queue->tq_queue); ins;
 209                      prev = ins, ins = STAILQ_NEXT(ins, ta_link))
 210                         if (ins->ta_priority < task->ta_priority)
 211                                 break;
 212
 213                 if (prev)
 214                         STAILQ_INSERT_AFTER(&queue->tq_queue, prev, task, ta_link);
 215                 else
 216                         STAILQ_INSERT_HEAD(&queue->tq_queue, task, ta_link);
 217         }
 218
 219         task->ta_pending = 1;
 220         if ((queue->tq_flags & TQ_FLAGS_BLOCKED) == 0) {
 221                 if (queue->tq_enqueue)
 222                         queue->tq_enqueue(queue->tq_context);
 223         } else {
 224                 queue->tq_flags |= TQ_FLAGS_PENDING;
 225         }
 226
 227         TQ_UNLOCK(queue);
 228
 229         return 0;
 230 }
 231
 232 void
 233 taskqueue_block(struct taskqueue *queue)
 234 {
 235         TQ_LOCK(queue);
 236         queue->tq_flags |= TQ_FLAGS_BLOCKED;
 237         TQ_UNLOCK(queue);
 238 }
 239
 240 void
 241 taskqueue_unblock(struct taskqueue *queue)
 242 {
 243         TQ_LOCK(queue);
 244         queue->tq_flags &= ~TQ_FLAGS_BLOCKED;
 245         if (queue->tq_flags & TQ_FLAGS_PENDING) {
 246                 queue->tq_flags &= ~TQ_FLAGS_PENDING;
 247                 if (queue->tq_enqueue)
 248                         queue->tq_enqueue(queue->tq_context);
 249         }
 250         TQ_UNLOCK(queue);
 251 }
 252
 253 void
 254 taskqueue_run(struct taskqueue *queue)
 255 {
 256         struct task *task;
 257         int pending;
 258
 259         TQ_LOCK(queue);
 260         while (STAILQ_FIRST(&queue->tq_queue)) {
 261                 /*
 262                  * Carefully remove the first task from the queue and
 263                  * zero its pending count.
 264                  */
 265                 task = STAILQ_FIRST(&queue->tq_queue);
 266                 STAILQ_REMOVE_HEAD(&queue->tq_queue, ta_link);
 267                 pending = task->ta_pending;
 268                 task->ta_pending = 0;
 269                 queue->tq_running = task;
 270                 TQ_UNLOCK(queue);
 271
 272                 task->ta_func(task->ta_context, pending);
 273
 274                 TQ_LOCK(queue);
 275                 queue->tq_running = NULL;
 276                 wakeup(task);
 277         }
 278         TQ_UNLOCK(queue);
 279 }
 280
 281 void
 282 taskqueue_drain(struct taskqueue *queue, struct task *task)
 283 {
 284         TQ_LOCK(queue);
 285         while (task->ta_pending != 0 || task == queue->tq_running)
 286                 TQ_SLEEP(queue, task, "-");
 287         TQ_UNLOCK(queue);
 288 }
 289
 290 static void
 291 taskqueue_swi_enqueue(void *context)
 292 {
 293         setsofttq();
 294 }
 295
 296 static void
 297 taskqueue_swi_run(void *arg, void *frame)
 298 {
 299         taskqueue_run(taskqueue_swi);
 300 }
 301
 302 static void
 303 taskqueue_swi_mp_run(void *arg, void *frame)
 304 {
 305         taskqueue_run(taskqueue_swi_mp);
 306 }
 307
 308 int
 309 taskqueue_start_threads(struct taskqueue **tqp, int count, int pri,
 310                         const char *fmt, ...)
 311 {
 312         __va_list ap;
 313         struct thread *td;
 314         struct taskqueue *tq;
 315         int i, error;
 316         char ktname[MAXCOMLEN];
 317
 318         if (count <= 0)
 319                 return EINVAL;
 320
 321         tq = *tqp;
 322
 323         __va_start(ap, fmt);
 324         kvsnprintf(ktname, MAXCOMLEN, fmt, ap);
 325         __va_end(ap);
 326
 327         tq->tq_threads = kmalloc(sizeof(struct thread *) * count, M_TASKQUEUE,
 328             M_WAITOK | M_ZERO);
 329
 330         for (i = 0; i < count; i++) {
 331                 error = lwkt_create(taskqueue_thread_loop, tqp,
 332                     &tq->tq_threads[i], NULL, TDF_STOPREQ | TDF_MPSAFE, -1,
 333                     "%s_%d", ktname, i);
 334                 if (error) {
 335                         kprintf("%s: kthread_add(%s): error %d", __func__,
 336                             ktname, error);
 337                         tq->tq_threads[i] = NULL;
 338                 } else {
 339                         td = tq->tq_threads[i];
 340                         lwkt_setpri(td, pri);
 341                         lwkt_schedule(td);
 342                         tq->tq_tcount++;
 343                 }
 344         }
 345
 346         return 0;
 347 }
 348
 349 void
 350 taskqueue_thread_loop(void *arg)
 351 {
 352         struct taskqueue **tqp, *tq;
 353
 354         tqp = arg;
 355         tq = *tqp;
 356         TQ_LOCK(tq);
 357         while ((tq->tq_flags & TQ_FLAGS_ACTIVE) != 0) {
 358                 taskqueue_run(tq);
 359                 TQ_SLEEP(tq, tq, "-");
 360         }
 361
 362         /* rendezvous with thread that asked us to terminate */
 363         tq->tq_tcount--;
 364         wakeup_one(tq->tq_threads);
 365         TQ_UNLOCK(tq);
 366         lwkt_exit();
 367 }
 368
 369 void
 370 taskqueue_thread_enqueue(void *context)
 371 {
 372         struct taskqueue **tqp, *tq;
 373
 374         tqp = context;
 375         tq = *tqp;
 376
 377         wakeup_one(tq);
 378 }
 379
 380 TASKQUEUE_DEFINE(swi, taskqueue_swi_enqueue, 0,
 381          register_swi(SWI_TQ, taskqueue_swi_run, NULL, "swi_taskq", NULL));
 382 /*
 383  * XXX: possibly use a different SWI_TQ_MP or so.
 384  * related: sys/interrupt.h
 385  * related: platform/XXX/isa/ipl_funcs.c
 386  */
 387 TASKQUEUE_DEFINE(swi_mp, taskqueue_swi_enqueue, 0,
 388          register_swi(SWI_TQ, taskqueue_swi_mp_run, NULL, "swi_mp_taskq", NULL));
 389
 390 static void
 391 taskqueue_kthread(void *arg)
 392 {
 393         struct taskqueue *queue = taskqueue_thread[mycpuid];
 394
 395         for (;;) {
 396                 taskqueue_run(queue);
 397                 TQ_LOCK(queue);
 398                 if (STAILQ_EMPTY(&queue->tq_queue))
 399                         TQ_SLEEP(queue, queue, "tqthr");
 400                 TQ_UNLOCK(queue);
 401         }
 402 }
 403
 404 static void
 405 taskqueue_kthread_enqueue(void *context)
 406 {
 407         wakeup(taskqueue_thread[mycpuid]);
 408 }
 409
 410 struct taskqueue *taskqueue_thread[MAXCPU];
 411 static struct thread *taskqueue_thread_td[MAXCPU];
 412
 413 static void
 414 taskqueue_init(void)
 415 {
 416         int cpu;
 417
 418         lockinit(&taskqueue_queues_lock, "tqqueues", 0, 0);
 419         STAILQ_INIT(&taskqueue_queues);
 420
 421         for (cpu = 0; cpu < ncpus; cpu++) {
 422                 taskqueue_thread[cpu] = taskqueue_create("thread", M_INTWAIT,
 423                     taskqueue_kthread_enqueue, NULL);
 424                 lwkt_create(taskqueue_kthread, NULL,
 425                     &taskqueue_thread_td[cpu], NULL,
 426                     0, cpu, "taskqueue %d", cpu);
 427         }
 428 }
 429
 430 SYSINIT(taskqueueinit, SI_SUB_PRE_DRIVERS, SI_ORDER_ANY, taskqueue_init, NULL);