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 void taskqueue_run(struct taskqueue *queue, int lock_held);
  70
  71 static __inline void
  72 TQ_LOCK_INIT(struct taskqueue *tq)
  73 {
  74         spin_init(&tq->tq_lock);
  75 }
  76
  77 static __inline void
  78 TQ_LOCK_UNINIT(struct taskqueue *tq)
  79 {
  80         spin_uninit(&tq->tq_lock);
  81 }
  82
  83 static __inline void
  84 TQ_LOCK(struct taskqueue *tq)
  85 {
  86         spin_lock_wr(&tq->tq_lock);
  87 }
  88
  89 static __inline void
  90 TQ_UNLOCK(struct taskqueue *tq)
  91 {
  92         spin_unlock_wr(&tq->tq_lock);
  93 }
  94
  95 static __inline void
  96 TQ_SLEEP(struct taskqueue *tq, void *ident, const char *wmesg)
  97 {
  98         ssleep(ident, &tq->tq_lock, 0, wmesg, 0);
  99 }
 100
 101 struct taskqueue *
 102 taskqueue_create(const char *name, int mflags,
 103                  taskqueue_enqueue_fn enqueue, void *context)
 104 {
 105         struct taskqueue *queue;
 106
 107         queue = kmalloc(sizeof(*queue), M_TASKQUEUE, mflags | M_ZERO);
 108         if (!queue)
 109                 return NULL;
 110         STAILQ_INIT(&queue->tq_queue);
 111         queue->tq_name = name;
 112         queue->tq_enqueue = enqueue;
 113         queue->tq_context = context;
 114         queue->tq_flags |= TQ_FLAGS_ACTIVE;
 115         TQ_LOCK_INIT(queue);
 116
 117         lockmgr(&taskqueue_queues_lock, LK_EXCLUSIVE);
 118         STAILQ_INSERT_TAIL(&taskqueue_queues, queue, tq_link);
 119         lockmgr(&taskqueue_queues_lock, LK_RELEASE);
 120
 121         return queue;
 122 }
 123
 124 static void
 125 taskqueue_terminate(struct thread **pp, struct taskqueue *tq)
 126 {
 127         while(tq->tq_tcount > 0) {
 128                 wakeup(tq);
 129                 TQ_SLEEP(tq, pp, "taskqueue_terminate");
 130         }
 131 }
 132
 133 void
 134 taskqueue_free(struct taskqueue *queue)
 135 {
 136         TQ_LOCK(queue);
 137         queue->tq_flags &= ~TQ_FLAGS_ACTIVE;
 138         taskqueue_run(queue, 1);
 139         taskqueue_terminate(queue->tq_threads, queue);
 140         TQ_UNLOCK(queue);
 141
 142         lockmgr(&taskqueue_queues_lock, LK_EXCLUSIVE);
 143         STAILQ_REMOVE(&taskqueue_queues, queue, taskqueue, tq_link);
 144         lockmgr(&taskqueue_queues_lock, LK_RELEASE);
 145
 146         TQ_LOCK_UNINIT(queue);
 147
 148         kfree(queue, M_TASKQUEUE);
 149 }
 150
 151 struct taskqueue *
 152 taskqueue_find(const char *name)
 153 {
 154         struct taskqueue *queue;
 155
 156         lockmgr(&taskqueue_queues_lock, LK_EXCLUSIVE);
 157         STAILQ_FOREACH(queue, &taskqueue_queues, tq_link) {
 158                 if (!strcmp(queue->tq_name, name)) {
 159                         lockmgr(&taskqueue_queues_lock, LK_RELEASE);
 160                         return queue;
 161                 }
 162         }
 163         lockmgr(&taskqueue_queues_lock, LK_RELEASE);
 164         return NULL;
 165 }
 166
 167 /*
 168  * NOTE!  If using the per-cpu taskqueues ``taskqueue_thread[mycpuid]'',
 169  * be sure NOT TO SHARE the ``task'' between CPUs.  TASKS ARE NOT LOCKED.
 170  * So either use a throwaway task which will only be enqueued once, or
 171  * use one task per CPU!
 172  */
 173 int
 174 taskqueue_enqueue(struct taskqueue *queue, struct task *task)
 175 {
 176         struct task *ins;
 177         struct task *prev;
 178
 179         TQ_LOCK(queue);
 180
 181         /*
 182          * Don't allow new tasks on a queue which is being freed.
 183          */
 184         if ((queue->tq_flags & TQ_FLAGS_ACTIVE) == 0) {
 185                 TQ_UNLOCK(queue);
 186                 return EPIPE;
 187         }
 188
 189         /*
 190          * Count multiple enqueues.
 191          */
 192         if (task->ta_pending) {
 193                 task->ta_pending++;
 194                 TQ_UNLOCK(queue);
 195                 return 0;
 196         }
 197
 198         /*
 199          * Optimise the case when all tasks have the same priority.
 200          */
 201         prev = STAILQ_LAST(&queue->tq_queue, task, ta_link);
 202         if (!prev || prev->ta_priority >= task->ta_priority) {
 203                 STAILQ_INSERT_TAIL(&queue->tq_queue, task, ta_link);
 204         } else {
 205                 prev = NULL;
 206                 for (ins = STAILQ_FIRST(&queue->tq_queue); ins;
 207                      prev = ins, ins = STAILQ_NEXT(ins, ta_link))
 208                         if (ins->ta_priority < task->ta_priority)
 209                                 break;
 210
 211                 if (prev)
 212                         STAILQ_INSERT_AFTER(&queue->tq_queue, prev, task, ta_link);
 213                 else
 214                         STAILQ_INSERT_HEAD(&queue->tq_queue, task, ta_link);
 215         }
 216
 217         task->ta_pending = 1;
 218         if ((queue->tq_flags & TQ_FLAGS_BLOCKED) == 0) {
 219                 if (queue->tq_enqueue)
 220                         queue->tq_enqueue(queue->tq_context);
 221         } else {
 222                 queue->tq_flags |= TQ_FLAGS_PENDING;
 223         }
 224
 225         TQ_UNLOCK(queue);
 226
 227         return 0;
 228 }
 229
 230 void
 231 taskqueue_block(struct taskqueue *queue)
 232 {
 233         TQ_LOCK(queue);
 234         queue->tq_flags |= TQ_FLAGS_BLOCKED;
 235         TQ_UNLOCK(queue);
 236 }
 237
 238 void
 239 taskqueue_unblock(struct taskqueue *queue)
 240 {
 241         TQ_LOCK(queue);
 242         queue->tq_flags &= ~TQ_FLAGS_BLOCKED;
 243         if (queue->tq_flags & TQ_FLAGS_PENDING) {
 244                 queue->tq_flags &= ~TQ_FLAGS_PENDING;
 245                 if (queue->tq_enqueue)
 246                         queue->tq_enqueue(queue->tq_context);
 247         }
 248         TQ_UNLOCK(queue);
 249 }
 250
 251 void
 252 taskqueue_run(struct taskqueue *queue, int lock_held)
 253 {
 254         struct task *task;
 255         int pending;
 256
 257         if (lock_held == 0)
 258                 TQ_LOCK(queue);
 259         while (STAILQ_FIRST(&queue->tq_queue)) {
 260                 /*
 261                  * Carefully remove the first task from the queue and
 262                  * zero its pending count.
 263                  */
 264                 task = STAILQ_FIRST(&queue->tq_queue);
 265                 STAILQ_REMOVE_HEAD(&queue->tq_queue, ta_link);
 266                 pending = task->ta_pending;
 267                 task->ta_pending = 0;
 268                 queue->tq_running = task;
 269                 TQ_UNLOCK(queue);
 270
 271                 task->ta_func(task->ta_context, pending);
 272
 273                 TQ_LOCK(queue);
 274                 queue->tq_running = NULL;
 275                 wakeup(task);
 276         }
 277         if (lock_held == 0)
 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, 0);
 300 }
 301
 302 static void
 303 taskqueue_swi_mp_run(void *arg, void *frame)
 304 {
 305         taskqueue_run(taskqueue_swi_mp, 0);
 306 }
 307
 308 int
 309 taskqueue_start_threads(struct taskqueue **tqp, int count, int pri, int ncpu,
 310                         const char *fmt, ...)
 311 {
 312         __va_list ap;
 313         struct thread *td;
 314         struct taskqueue *tq;
 315         int i, error, cpu;
 316         char ktname[MAXCOMLEN];
 317
 318         if (count <= 0)
 319                 return EINVAL;
 320
 321         tq = *tqp;
 322         cpu = ncpu;
 323
 324         __va_start(ap, fmt);
 325         kvsnprintf(ktname, MAXCOMLEN, fmt, ap);
 326         __va_end(ap);
 327
 328         tq->tq_threads = kmalloc(sizeof(struct thread *) * count, M_TASKQUEUE,
 329             M_WAITOK | M_ZERO);
 330
 331         for (i = 0; i < count; i++) {
 332                 /*
 333                  * If no specific cpu was specified and more than one thread
 334                  * is to be created, we distribute the threads amongst all
 335                  * cpus.
 336                  */
 337                 if ((ncpu <= -1) && (count > 1))
 338                         cpu = i%ncpus;
 339
 340                 if (count == 1) {
 341                         error = lwkt_create(taskqueue_thread_loop, tqp,
 342                             &tq->tq_threads[i], NULL, TDF_STOPREQ | TDF_MPSAFE,
 343                             cpu, "%s", ktname);
 344                 } else {
 345                         error = lwkt_create(taskqueue_thread_loop, tqp,
 346                             &tq->tq_threads[i], NULL, TDF_STOPREQ | TDF_MPSAFE,
 347                             cpu, "%s_%d", ktname, i);
 348                 }
 349                 if (error) {
 350                         kprintf("%s: kthread_add(%s): error %d", __func__,
 351                             ktname, error);
 352                         tq->tq_threads[i] = NULL;
 353                 } else {
 354                         td = tq->tq_threads[i];
 355                         lwkt_setpri_initial(td, pri);
 356                         lwkt_schedule(td);
 357                         tq->tq_tcount++;
 358                 }
 359         }
 360
 361         return 0;
 362 }
 363
 364 void
 365 taskqueue_thread_loop(void *arg)
 366 {
 367         struct taskqueue **tqp, *tq;
 368
 369         tqp = arg;
 370         tq = *tqp;
 371         TQ_LOCK(tq);
 372         while ((tq->tq_flags & TQ_FLAGS_ACTIVE) != 0) {
 373                 taskqueue_run(tq, 1);
 374                 TQ_SLEEP(tq, tq, "tqthr");
 375         }
 376
 377         /* rendezvous with thread that asked us to terminate */
 378         tq->tq_tcount--;
 379         wakeup_one(tq->tq_threads);
 380         TQ_UNLOCK(tq);
 381         lwkt_exit();
 382 }
 383
 384 void
 385 taskqueue_thread_enqueue(void *context)
 386 {
 387         struct taskqueue **tqp, *tq;
 388
 389         tqp = context;
 390         tq = *tqp;
 391
 392         wakeup_one(tq);
 393 }
 394
 395 TASKQUEUE_DEFINE(swi, taskqueue_swi_enqueue, 0,
 396          register_swi(SWI_TQ, taskqueue_swi_run, NULL, "swi_taskq", NULL));
 397 /*
 398  * XXX: possibly use a different SWI_TQ_MP or so.
 399  * related: sys/interrupt.h
 400  * related: platform/XXX/isa/ipl_funcs.c
 401  */
 402 TASKQUEUE_DEFINE(swi_mp, taskqueue_swi_enqueue, 0,
 403          register_swi(SWI_TQ, taskqueue_swi_mp_run, NULL, "swi_mp_taskq", NULL));
 404
 405 struct taskqueue *taskqueue_thread[MAXCPU];
 406
 407 static void
 408 taskqueue_init(void)
 409 {
 410         int cpu;
 411
 412         lockinit(&taskqueue_queues_lock, "tqqueues", 0, 0);
 413         STAILQ_INIT(&taskqueue_queues);
 414
 415         for (cpu = 0; cpu < ncpus; cpu++) {
 416                 taskqueue_thread[cpu] = taskqueue_create("thread", M_INTWAIT,
 417                     taskqueue_thread_enqueue, &taskqueue_thread[cpu]);
 418                 taskqueue_start_threads(&taskqueue_thread[cpu], 1,
 419                     TDPRI_KERN_DAEMON, cpu, "taskq_cpu %d", cpu);
 420         }
 421 }
 422
 423 SYSINIT(taskqueueinit, SI_SUB_PRE_DRIVERS, SI_ORDER_ANY, taskqueue_init, NULL);