subr_taskqueue.c revision 210377
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: head/sys/kern/subr_taskqueue.c 210377 2010-07-22 16:41:09Z mdf $"); 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 45static MALLOC_DEFINE(M_TASKQUEUE, "taskqueue", "Task Queues"); 46static void *taskqueue_giant_ih; 47static void *taskqueue_ih; 48 49struct 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 66static void taskqueue_run(struct taskqueue *, struct task **); 67 68static __inline void 69TQ_LOCK(struct taskqueue *tq) 70{ 71 if (tq->tq_spin) 72 mtx_lock_spin(&tq->tq_mutex); 73 else 74 mtx_lock(&tq->tq_mutex); 75} 76 77static __inline void 78TQ_UNLOCK(struct taskqueue *tq) 79{ 80 if (tq->tq_spin) 81 mtx_unlock_spin(&tq->tq_mutex); 82 else 83 mtx_unlock(&tq->tq_mutex); 84} 85 86static __inline int 87TQ_SLEEP(struct taskqueue *tq, void *p, struct mtx *m, int pri, const char *wm, 88 int t) 89{ 90 if (tq->tq_spin) 91 return (msleep_spin(p, m, wm, t)); 92 return (msleep(p, m, pri, wm, t)); 93} 94 95static struct taskqueue * 96_taskqueue_create(const char *name, int mflags, 97 taskqueue_enqueue_fn enqueue, void *context, 98 int mtxflags, const char *mtxname) 99{ 100 struct taskqueue *queue; 101 102 queue = malloc(sizeof(struct taskqueue), M_TASKQUEUE, mflags | M_ZERO); 103 if (!queue) 104 return NULL; 105 106 STAILQ_INIT(&queue->tq_queue); 107 queue->tq_name = name; 108 queue->tq_enqueue = enqueue; 109 queue->tq_context = context; 110 queue->tq_spin = (mtxflags & MTX_SPIN) != 0; 111 queue->tq_flags |= TQ_FLAGS_ACTIVE; 112 mtx_init(&queue->tq_mutex, mtxname, NULL, mtxflags); 113 114 return queue; 115} 116 117struct taskqueue * 118taskqueue_create(const char *name, int mflags, 119 taskqueue_enqueue_fn enqueue, void *context) 120{ 121 return _taskqueue_create(name, mflags, enqueue, context, 122 MTX_DEF, "taskqueue"); 123} 124 125/* 126 * Signal a taskqueue thread to terminate. 127 */ 128static void 129taskqueue_terminate(struct thread **pp, struct taskqueue *tq) 130{ 131 132 while (tq->tq_tcount > 0) { 133 wakeup(tq); 134 TQ_SLEEP(tq, pp, &tq->tq_mutex, PWAIT, "taskqueue_destroy", 0); 135 } 136} 137 138void 139taskqueue_free(struct taskqueue *queue) 140{ 141 142 TQ_LOCK(queue); 143 queue->tq_flags &= ~TQ_FLAGS_ACTIVE; 144 taskqueue_run(queue, &queue->tq_running); 145 taskqueue_terminate(queue->tq_threads, queue); 146 mtx_destroy(&queue->tq_mutex); 147 free(queue->tq_threads, M_TASKQUEUE); 148 free(queue, M_TASKQUEUE); 149} 150 151int 152taskqueue_enqueue(struct taskqueue *queue, struct task *task) 153{ 154 struct task *ins; 155 struct task *prev; 156 157 TQ_LOCK(queue); 158 159 /* 160 * Count multiple enqueues. 161 */ 162 if (task->ta_pending) { 163 task->ta_pending++; 164 TQ_UNLOCK(queue); 165 return 0; 166 } 167 168 /* 169 * Optimise the case when all tasks have the same priority. 170 */ 171 prev = STAILQ_LAST(&queue->tq_queue, task, ta_link); 172 if (!prev || prev->ta_priority >= task->ta_priority) { 173 STAILQ_INSERT_TAIL(&queue->tq_queue, task, ta_link); 174 } else { 175 prev = NULL; 176 for (ins = STAILQ_FIRST(&queue->tq_queue); ins; 177 prev = ins, ins = STAILQ_NEXT(ins, ta_link)) 178 if (ins->ta_priority < task->ta_priority) 179 break; 180 181 if (prev) 182 STAILQ_INSERT_AFTER(&queue->tq_queue, prev, task, ta_link); 183 else 184 STAILQ_INSERT_HEAD(&queue->tq_queue, task, ta_link); 185 } 186 187 task->ta_pending = 1; 188 if ((queue->tq_flags & TQ_FLAGS_BLOCKED) == 0) 189 queue->tq_enqueue(queue->tq_context); 190 else 191 queue->tq_flags |= TQ_FLAGS_PENDING; 192 193 TQ_UNLOCK(queue); 194 195 return 0; 196} 197 198void 199taskqueue_block(struct taskqueue *queue) 200{ 201 202 TQ_LOCK(queue); 203 queue->tq_flags |= TQ_FLAGS_BLOCKED; 204 TQ_UNLOCK(queue); 205} 206 207void 208taskqueue_unblock(struct taskqueue *queue) 209{ 210 211 TQ_LOCK(queue); 212 queue->tq_flags &= ~TQ_FLAGS_BLOCKED; 213 if (queue->tq_flags & TQ_FLAGS_PENDING) { 214 queue->tq_flags &= ~TQ_FLAGS_PENDING; 215 queue->tq_enqueue(queue->tq_context); 216 } 217 TQ_UNLOCK(queue); 218} 219 220static void 221taskqueue_run(struct taskqueue *queue, struct task **tpp) 222{ 223 struct task *task, *running; 224 int pending; 225 226 mtx_assert(&queue->tq_mutex, MA_OWNED); 227 running = NULL; 228 while (STAILQ_FIRST(&queue->tq_queue)) { 229 /* 230 * Carefully remove the first task from the queue and 231 * zero its pending count. 232 */ 233 task = STAILQ_FIRST(&queue->tq_queue); 234 STAILQ_REMOVE_HEAD(&queue->tq_queue, ta_link); 235 pending = task->ta_pending; 236 task->ta_pending = 0; 237 task->ta_running = tpp; 238 *tpp = task; 239 TQ_UNLOCK(queue); 240 241 task->ta_func(task->ta_context, pending); 242 243 TQ_LOCK(queue); 244 *tpp = NULL; 245 wakeup(task); 246 } 247} 248 249void 250taskqueue_drain(struct taskqueue *queue, struct task *task) 251{ 252 if (queue->tq_spin) { /* XXX */ 253 mtx_lock_spin(&queue->tq_mutex); 254 while (task->ta_pending != 0 || 255 (task->ta_running != NULL && task == *task->ta_running)) { 256 msleep_spin(task, &queue->tq_mutex, "-", 0); 257 } 258 mtx_unlock_spin(&queue->tq_mutex); 259 } else { 260 WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, NULL, __func__); 261 262 mtx_lock(&queue->tq_mutex); 263 while (task->ta_pending != 0 || 264 (task->ta_running != NULL && task == *task->ta_running)) { 265 msleep(task, &queue->tq_mutex, PWAIT, "-", 0); 266 } 267 mtx_unlock(&queue->tq_mutex); 268 } 269} 270 271static void 272taskqueue_swi_enqueue(void *context) 273{ 274 swi_sched(taskqueue_ih, 0); 275} 276 277static void 278taskqueue_swi_run(void *dummy) 279{ 280 TQ_LOCK(taskqueue_swi); 281 taskqueue_run(taskqueue_swi, &taskqueue_swi->tq_running); 282 TQ_UNLOCK(taskqueue_swi); 283} 284 285static void 286taskqueue_swi_giant_enqueue(void *context) 287{ 288 swi_sched(taskqueue_giant_ih, 0); 289} 290 291static void 292taskqueue_swi_giant_run(void *dummy) 293{ 294 TQ_LOCK(taskqueue_swi_giant); 295 taskqueue_run(taskqueue_swi_giant, &taskqueue_swi_giant->tq_running); 296 TQ_UNLOCK(taskqueue_swi_giant); 297} 298 299int 300taskqueue_start_threads(struct taskqueue **tqp, int count, int pri, 301 const char *name, ...) 302{ 303 va_list ap; 304 struct thread *td; 305 struct taskqueue *tq; 306 int i, error; 307 char ktname[MAXCOMLEN + 1]; 308 309 if (count <= 0) 310 return (EINVAL); 311 312 tq = *tqp; 313 314 va_start(ap, name); 315 vsnprintf(ktname, sizeof(ktname), name, ap); 316 va_end(ap); 317 318 tq->tq_threads = malloc(sizeof(struct thread *) * count, M_TASKQUEUE, 319 M_NOWAIT | M_ZERO); 320 if (tq->tq_threads == NULL) { 321 printf("%s: no memory for %s threads\n", __func__, ktname); 322 return (ENOMEM); 323 } 324 325 for (i = 0; i < count; i++) { 326 if (count == 1) 327 error = kthread_add(taskqueue_thread_loop, tqp, NULL, 328 &tq->tq_threads[i], RFSTOPPED, 0, "%s", ktname); 329 else 330 error = kthread_add(taskqueue_thread_loop, tqp, NULL, 331 &tq->tq_threads[i], RFSTOPPED, 0, 332 "%s_%d", ktname, i); 333 if (error) { 334 /* should be ok to continue, taskqueue_free will dtrt */ 335 printf("%s: kthread_add(%s): error %d", __func__, 336 ktname, error); 337 tq->tq_threads[i] = NULL; /* paranoid */ 338 } else 339 tq->tq_tcount++; 340 } 341 for (i = 0; i < count; i++) { 342 if (tq->tq_threads[i] == NULL) 343 continue; 344 td = tq->tq_threads[i]; 345 thread_lock(td); 346 sched_prio(td, pri); 347 sched_add(td, SRQ_BORING); 348 thread_unlock(td); 349 } 350 351 return (0); 352} 353 354void 355taskqueue_thread_loop(void *arg) 356{ 357 struct taskqueue **tqp, *tq; 358 struct task *running; 359 360 /* 361 * The kernel stack space is globaly addressable, and it would 362 * be an error to ask whether a task is running after the 363 * taskqueue has been released. So it is safe to have the 364 * task point back to an address in the taskqueue's stack to 365 * determine if the task is running. 366 */ 367 running = NULL; 368 369 tqp = arg; 370 tq = *tqp; 371 TQ_LOCK(tq); 372 while ((tq->tq_flags & TQ_FLAGS_ACTIVE) != 0) { 373 taskqueue_run(tq, &running); 374 /* 375 * Because taskqueue_run() can drop tq_mutex, we need to 376 * check if the TQ_FLAGS_ACTIVE flag wasn't removed in the 377 * meantime, which means we missed a wakeup. 378 */ 379 if ((tq->tq_flags & TQ_FLAGS_ACTIVE) == 0) 380 break; 381 TQ_SLEEP(tq, tq, &tq->tq_mutex, 0, "-", 0); 382 } 383 384 /* rendezvous with thread that asked us to terminate */ 385 tq->tq_tcount--; 386 wakeup_one(tq->tq_threads); 387 TQ_UNLOCK(tq); 388 kthread_exit(); 389} 390 391void 392taskqueue_thread_enqueue(void *context) 393{ 394 struct taskqueue **tqp, *tq; 395 396 tqp = context; 397 tq = *tqp; 398 399 mtx_assert(&tq->tq_mutex, MA_OWNED); 400 wakeup_one(tq); 401} 402 403TASKQUEUE_DEFINE(swi, taskqueue_swi_enqueue, NULL, 404 swi_add(NULL, "task queue", taskqueue_swi_run, NULL, SWI_TQ, 405 INTR_MPSAFE, &taskqueue_ih)); 406 407TASKQUEUE_DEFINE(swi_giant, taskqueue_swi_giant_enqueue, NULL, 408 swi_add(NULL, "Giant taskq", taskqueue_swi_giant_run, 409 NULL, SWI_TQ_GIANT, 0, &taskqueue_giant_ih)); 410 411TASKQUEUE_DEFINE_THREAD(thread); 412 413struct taskqueue * 414taskqueue_create_fast(const char *name, int mflags, 415 taskqueue_enqueue_fn enqueue, void *context) 416{ 417 return _taskqueue_create(name, mflags, enqueue, context, 418 MTX_SPIN, "fast_taskqueue"); 419} 420 421/* NB: for backwards compatibility */ 422int 423taskqueue_enqueue_fast(struct taskqueue *queue, struct task *task) 424{ 425 return taskqueue_enqueue(queue, task); 426} 427 428static void *taskqueue_fast_ih; 429 430static void 431taskqueue_fast_enqueue(void *context) 432{ 433 swi_sched(taskqueue_fast_ih, 0); 434} 435 436static void 437taskqueue_fast_run(void *dummy) 438{ 439 TQ_LOCK(taskqueue_fast); 440 taskqueue_run(taskqueue_fast, &taskqueue_fast->tq_running); 441 TQ_UNLOCK(taskqueue_fast); 442} 443 444TASKQUEUE_FAST_DEFINE(fast, taskqueue_fast_enqueue, NULL, 445 swi_add(NULL, "Fast task queue", taskqueue_fast_run, NULL, 446 SWI_TQ_FAST, INTR_MPSAFE, &taskqueue_fast_ih)); 447 448int 449taskqueue_member(struct taskqueue *queue, struct thread *td) 450{ 451 int i, j, ret = 0; 452 453 TQ_LOCK(queue); 454 for (i = 0, j = 0; ; i++) { 455 if (queue->tq_threads[i] == NULL) 456 continue; 457 if (queue->tq_threads[i] == td) { 458 ret = 1; 459 break; 460 } 461 if (++j >= queue->tq_tcount) 462 break; 463 } 464 TQ_UNLOCK(queue); 465 return (ret); 466} 467