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