1 /*- 2 * Copyright (c) 1982, 1986, 1991, 1993 3 * The Regents of the University of California. All rights reserved. 4 * (c) UNIX System Laboratories, Inc. 5 * All or some portions of this file are derived from material licensed 6 * to the University of California by American Telephone and Telegraph 7 * Co. or Unix System Laboratories, Inc. and are reproduced herein with 8 * the permission of UNIX System Laboratories, Inc. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 4. Neither the name of the University nor the names of its contributors 19 * may be used to endorse or promote products derived from this software 20 * without specific prior written permission. 21 * 22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32 * SUCH DAMAGE. 33 * 34 * From: @(#)kern_clock.c 8.5 (Berkeley) 1/21/94 35 */ 36 37 #include <sys/cdefs.h> 38 __FBSDID("$FreeBSD$"); 39 40 #include <sys/param.h> 41 #include <sys/systm.h> 42 #include <sys/bus.h> 43 #include <sys/callout.h> 44 #include <sys/condvar.h> 45 #include <sys/interrupt.h> 46 #include <sys/kernel.h> 47 #include <sys/ktr.h> 48 #include <sys/lock.h> 49 #include <sys/malloc.h> 50 #include <sys/mutex.h> 51 #include <sys/proc.h> 52 #include <sys/sleepqueue.h> 53 #include <sys/sysctl.h> 54 #include <sys/smp.h> 55 56 static int avg_depth; 57 SYSCTL_INT(_debug, OID_AUTO, to_avg_depth, CTLFLAG_RD, &avg_depth, 0, 58 "Average number of items examined per softclock call. Units = 1/1000"); 59 static int avg_gcalls; 60 SYSCTL_INT(_debug, OID_AUTO, to_avg_gcalls, CTLFLAG_RD, &avg_gcalls, 0, 61 "Average number of Giant callouts made per softclock call. Units = 1/1000"); 62 static int avg_lockcalls; 63 SYSCTL_INT(_debug, OID_AUTO, to_avg_lockcalls, CTLFLAG_RD, &avg_lockcalls, 0, 64 "Average number of lock callouts made per softclock call. Units = 1/1000"); 65 static int avg_mpcalls; 66 SYSCTL_INT(_debug, OID_AUTO, to_avg_mpcalls, CTLFLAG_RD, &avg_mpcalls, 0, 67 "Average number of MP callouts made per softclock call. Units = 1/1000"); 68 /* 69 * TODO: 70 * allocate more timeout table slots when table overflows. 71 */ 72 int callwheelsize, callwheelbits, callwheelmask; 73 74 struct callout_cpu { 75 struct mtx cc_lock; 76 struct callout *cc_callout; 77 struct callout_tailq *cc_callwheel; 78 struct callout_list cc_callfree; 79 struct callout *cc_next; 80 struct callout *cc_curr; 81 void *cc_cookie; 82 int cc_softticks; 83 int cc_cancel; 84 int cc_waiting; 85 }; 86 87 #ifdef SMP 88 struct callout_cpu cc_cpu[MAXCPU]; 89 #define CC_CPU(cpu) (&cc_cpu[(cpu)]) 90 #define CC_SELF() CC_CPU(PCPU_GET(cpuid)) 91 #else 92 struct callout_cpu cc_cpu; 93 #define CC_CPU(cpu) &cc_cpu 94 #define CC_SELF() &cc_cpu 95 #endif 96 #define CC_LOCK(cc) mtx_lock_spin(&(cc)->cc_lock) 97 #define CC_UNLOCK(cc) mtx_unlock_spin(&(cc)->cc_lock) 98 99 static int timeout_cpu; 100 101 MALLOC_DEFINE(M_CALLOUT, "callout", "Callout datastructures"); 102 103 /** 104 * Locked by cc_lock: 105 * cc_curr - If a callout is in progress, it is curr_callout. 106 * If curr_callout is non-NULL, threads waiting in 107 * callout_drain() will be woken up as soon as the 108 * relevant callout completes. 109 * cc_cancel - Changing to 1 with both callout_lock and c_lock held 110 * guarantees that the current callout will not run. 111 * The softclock() function sets this to 0 before it 112 * drops callout_lock to acquire c_lock, and it calls 113 * the handler only if curr_cancelled is still 0 after 114 * c_lock is successfully acquired. 115 * cc_waiting - If a thread is waiting in callout_drain(), then 116 * callout_wait is nonzero. Set only when 117 * curr_callout is non-NULL. 118 */ 119 120 /* 121 * kern_timeout_callwheel_alloc() - kernel low level callwheel initialization 122 * 123 * This code is called very early in the kernel initialization sequence, 124 * and may be called more then once. 125 */ 126 caddr_t 127 kern_timeout_callwheel_alloc(caddr_t v) 128 { 129 struct callout_cpu *cc; 130 131 timeout_cpu = PCPU_GET(cpuid); 132 cc = CC_CPU(timeout_cpu); 133 /* 134 * Calculate callout wheel size 135 */ 136 for (callwheelsize = 1, callwheelbits = 0; 137 callwheelsize < ncallout; 138 callwheelsize <<= 1, ++callwheelbits) 139 ; 140 callwheelmask = callwheelsize - 1; 141 142 cc->cc_callout = (struct callout *)v; 143 v = (caddr_t)(cc->cc_callout + ncallout); 144 cc->cc_callwheel = (struct callout_tailq *)v; 145 v = (caddr_t)(cc->cc_callwheel + callwheelsize); 146 return(v); 147 } 148 149 static void 150 callout_cpu_init(struct callout_cpu *cc) 151 { 152 struct callout *c; 153 int i; 154 155 mtx_init(&cc->cc_lock, "callout", NULL, MTX_SPIN | MTX_RECURSE); 156 SLIST_INIT(&cc->cc_callfree); 157 for (i = 0; i < callwheelsize; i++) { 158 TAILQ_INIT(&cc->cc_callwheel[i]); 159 } 160 if (cc->cc_callout == NULL) 161 return; 162 for (i = 0; i < ncallout; i++) { 163 c = &cc->cc_callout[i]; 164 callout_init(c, 0); 165 c->c_flags = CALLOUT_LOCAL_ALLOC; 166 SLIST_INSERT_HEAD(&cc->cc_callfree, c, c_links.sle); 167 } 168 } 169 170 /* 171 * kern_timeout_callwheel_init() - initialize previously reserved callwheel 172 * space. 173 * 174 * This code is called just once, after the space reserved for the 175 * callout wheel has been finalized. 176 */ 177 void 178 kern_timeout_callwheel_init(void) 179 { 180 callout_cpu_init(CC_CPU(timeout_cpu)); 181 } 182 183 /* 184 * Start standard softclock thread. 185 */ 186 void *softclock_ih; 187 188 static void 189 start_softclock(void *dummy) 190 { 191 struct callout_cpu *cc; 192 #ifdef SMP 193 int cpu; 194 #endif 195 196 cc = CC_CPU(timeout_cpu); 197 if (swi_add(&clk_intr_event, "clock", softclock, cc, SWI_CLOCK, 198 INTR_MPSAFE, &softclock_ih)) 199 panic("died while creating standard software ithreads"); 200 cc->cc_cookie = softclock_ih; 201 #ifdef SMP 202 for (cpu = 0; cpu <= mp_maxid; cpu++) { 203 if (cpu == timeout_cpu) 204 continue; 205 if (CPU_ABSENT(cpu)) 206 continue; 207 cc = CC_CPU(cpu); 208 if (swi_add(NULL, "clock", softclock, cc, SWI_CLOCK, 209 INTR_MPSAFE, &cc->cc_cookie)) 210 panic("died while creating standard software ithreads"); 211 cc->cc_callout = NULL; /* Only cpu0 handles timeout(). */ 212 cc->cc_callwheel = malloc( 213 sizeof(struct callout_tailq) * callwheelsize, M_CALLOUT, 214 M_WAITOK); 215 callout_cpu_init(cc); 216 } 217 #endif 218 } 219 220 SYSINIT(start_softclock, SI_SUB_SOFTINTR, SI_ORDER_FIRST, start_softclock, NULL); 221 222 void 223 callout_tick(void) 224 { 225 struct callout_cpu *cc; 226 int need_softclock; 227 int bucket; 228 229 /* 230 * Process callouts at a very low cpu priority, so we don't keep the 231 * relatively high clock interrupt priority any longer than necessary. 232 */ 233 need_softclock = 0; 234 cc = CC_SELF(); 235 mtx_lock_spin_flags(&cc->cc_lock, MTX_QUIET); 236 for (; (cc->cc_softticks - ticks) < 0; cc->cc_softticks++) { 237 bucket = cc->cc_softticks & callwheelmask; 238 if (!TAILQ_EMPTY(&cc->cc_callwheel[bucket])) { 239 need_softclock = 1; 240 break; 241 } 242 } 243 mtx_unlock_spin_flags(&cc->cc_lock, MTX_QUIET); 244 /* 245 * swi_sched acquires the thread lock, so we don't want to call it 246 * with cc_lock held; incorrect locking order. 247 */ 248 if (need_softclock) 249 swi_sched(cc->cc_cookie, 0); 250 } 251 252 static struct callout_cpu * 253 callout_lock(struct callout *c) 254 { 255 struct callout_cpu *cc; 256 int cpu; 257 258 for (;;) { 259 cpu = c->c_cpu; 260 cc = CC_CPU(cpu); 261 CC_LOCK(cc); 262 if (cpu == c->c_cpu) 263 break; 264 CC_UNLOCK(cc); 265 } 266 return (cc); 267 } 268 269 /* 270 * The callout mechanism is based on the work of Adam M. Costello and 271 * George Varghese, published in a technical report entitled "Redesigning 272 * the BSD Callout and Timer Facilities" and modified slightly for inclusion 273 * in FreeBSD by Justin T. Gibbs. The original work on the data structures 274 * used in this implementation was published by G. Varghese and T. Lauck in 275 * the paper "Hashed and Hierarchical Timing Wheels: Data Structures for 276 * the Efficient Implementation of a Timer Facility" in the Proceedings of 277 * the 11th ACM Annual Symposium on Operating Systems Principles, 278 * Austin, Texas Nov 1987. 279 */ 280 281 /* 282 * Software (low priority) clock interrupt. 283 * Run periodic events from timeout queue. 284 */ 285 void 286 softclock(void *arg) 287 { 288 struct callout_cpu *cc; 289 struct callout *c; 290 struct callout_tailq *bucket; 291 int curticks; 292 int steps; /* #steps since we last allowed interrupts */ 293 int depth; 294 int mpcalls; 295 int lockcalls; 296 int gcalls; 297 #ifdef DIAGNOSTIC 298 struct bintime bt1, bt2; 299 struct timespec ts2; 300 static uint64_t maxdt = 36893488147419102LL; /* 2 msec */ 301 static timeout_t *lastfunc; 302 #endif 303 304 #ifndef MAX_SOFTCLOCK_STEPS 305 #define MAX_SOFTCLOCK_STEPS 100 /* Maximum allowed value of steps. */ 306 #endif /* MAX_SOFTCLOCK_STEPS */ 307 308 mpcalls = 0; 309 lockcalls = 0; 310 gcalls = 0; 311 depth = 0; 312 steps = 0; 313 cc = (struct callout_cpu *)arg; 314 CC_LOCK(cc); 315 while (cc->cc_softticks != ticks) { 316 /* 317 * cc_softticks may be modified by hard clock, so cache 318 * it while we work on a given bucket. 319 */ 320 curticks = cc->cc_softticks; 321 cc->cc_softticks++; 322 bucket = &cc->cc_callwheel[curticks & callwheelmask]; 323 c = TAILQ_FIRST(bucket); 324 while (c) { 325 depth++; 326 if (c->c_time != curticks) { 327 c = TAILQ_NEXT(c, c_links.tqe); 328 ++steps; 329 if (steps >= MAX_SOFTCLOCK_STEPS) { 330 cc->cc_next = c; 331 /* Give interrupts a chance. */ 332 CC_UNLOCK(cc); 333 ; /* nothing */ 334 CC_LOCK(cc); 335 c = cc->cc_next; 336 steps = 0; 337 } 338 } else { 339 void (*c_func)(void *); 340 void *c_arg; 341 struct lock_class *class; 342 struct lock_object *c_lock; 343 int c_flags, sharedlock; 344 345 cc->cc_next = TAILQ_NEXT(c, c_links.tqe); 346 TAILQ_REMOVE(bucket, c, c_links.tqe); 347 class = (c->c_lock != NULL) ? 348 LOCK_CLASS(c->c_lock) : NULL; 349 sharedlock = (c->c_flags & CALLOUT_SHAREDLOCK) ? 350 0 : 1; 351 c_lock = c->c_lock; 352 c_func = c->c_func; 353 c_arg = c->c_arg; 354 c_flags = c->c_flags; 355 if (c->c_flags & CALLOUT_LOCAL_ALLOC) { 356 c->c_flags = CALLOUT_LOCAL_ALLOC; 357 } else { 358 c->c_flags = 359 (c->c_flags & ~CALLOUT_PENDING); 360 } 361 cc->cc_curr = c; 362 cc->cc_cancel = 0; 363 CC_UNLOCK(cc); 364 if (c_lock != NULL) { 365 class->lc_lock(c_lock, sharedlock); 366 /* 367 * The callout may have been cancelled 368 * while we switched locks. 369 */ 370 if (cc->cc_cancel) { 371 class->lc_unlock(c_lock); 372 goto skip; 373 } 374 /* The callout cannot be stopped now. */ 375 cc->cc_cancel = 1; 376 377 if (c_lock == &Giant.lock_object) { 378 gcalls++; 379 CTR3(KTR_CALLOUT, 380 "callout %p func %p arg %p", 381 c, c_func, c_arg); 382 } else { 383 lockcalls++; 384 CTR3(KTR_CALLOUT, "callout lock" 385 " %p func %p arg %p", 386 c, c_func, c_arg); 387 } 388 } else { 389 mpcalls++; 390 CTR3(KTR_CALLOUT, 391 "callout mpsafe %p func %p arg %p", 392 c, c_func, c_arg); 393 } 394 #ifdef DIAGNOSTIC 395 binuptime(&bt1); 396 #endif 397 THREAD_NO_SLEEPING(); 398 c_func(c_arg); 399 THREAD_SLEEPING_OK(); 400 #ifdef DIAGNOSTIC 401 binuptime(&bt2); 402 bintime_sub(&bt2, &bt1); 403 if (bt2.frac > maxdt) { 404 if (lastfunc != c_func || 405 bt2.frac > maxdt * 2) { 406 bintime2timespec(&bt2, &ts2); 407 printf( 408 "Expensive timeout(9) function: %p(%p) %jd.%09ld s\n", 409 c_func, c_arg, 410 (intmax_t)ts2.tv_sec, 411 ts2.tv_nsec); 412 } 413 maxdt = bt2.frac; 414 lastfunc = c_func; 415 } 416 #endif 417 CTR1(KTR_CALLOUT, "callout %p finished", c); 418 if ((c_flags & CALLOUT_RETURNUNLOCKED) == 0) 419 class->lc_unlock(c_lock); 420 skip: 421 CC_LOCK(cc); 422 /* 423 * If the current callout is locally 424 * allocated (from timeout(9)) 425 * then put it on the freelist. 426 * 427 * Note: we need to check the cached 428 * copy of c_flags because if it was not 429 * local, then it's not safe to deref the 430 * callout pointer. 431 */ 432 if (c_flags & CALLOUT_LOCAL_ALLOC) { 433 KASSERT(c->c_flags == 434 CALLOUT_LOCAL_ALLOC, 435 ("corrupted callout")); 436 c->c_func = NULL; 437 SLIST_INSERT_HEAD(&cc->cc_callfree, c, 438 c_links.sle); 439 } 440 cc->cc_curr = NULL; 441 if (cc->cc_waiting) { 442 /* 443 * There is someone waiting 444 * for the callout to complete. 445 */ 446 cc->cc_waiting = 0; 447 CC_UNLOCK(cc); 448 wakeup(&cc->cc_waiting); 449 CC_LOCK(cc); 450 } 451 steps = 0; 452 c = cc->cc_next; 453 } 454 } 455 } 456 avg_depth += (depth * 1000 - avg_depth) >> 8; 457 avg_mpcalls += (mpcalls * 1000 - avg_mpcalls) >> 8; 458 avg_lockcalls += (lockcalls * 1000 - avg_lockcalls) >> 8; 459 avg_gcalls += (gcalls * 1000 - avg_gcalls) >> 8; 460 cc->cc_next = NULL; 461 CC_UNLOCK(cc); 462 } 463 464 /* 465 * timeout -- 466 * Execute a function after a specified length of time. 467 * 468 * untimeout -- 469 * Cancel previous timeout function call. 470 * 471 * callout_handle_init -- 472 * Initialize a handle so that using it with untimeout is benign. 473 * 474 * See AT&T BCI Driver Reference Manual for specification. This 475 * implementation differs from that one in that although an 476 * identification value is returned from timeout, the original 477 * arguments to timeout as well as the identifier are used to 478 * identify entries for untimeout. 479 */ 480 struct callout_handle 481 timeout(ftn, arg, to_ticks) 482 timeout_t *ftn; 483 void *arg; 484 int to_ticks; 485 { 486 struct callout_cpu *cc; 487 struct callout *new; 488 struct callout_handle handle; 489 490 cc = CC_CPU(timeout_cpu); 491 CC_LOCK(cc); 492 /* Fill in the next free callout structure. */ 493 new = SLIST_FIRST(&cc->cc_callfree); 494 if (new == NULL) 495 /* XXX Attempt to malloc first */ 496 panic("timeout table full"); 497 SLIST_REMOVE_HEAD(&cc->cc_callfree, c_links.sle); 498 callout_reset(new, to_ticks, ftn, arg); 499 handle.callout = new; 500 CC_UNLOCK(cc); 501 502 return (handle); 503 } 504 505 void 506 untimeout(ftn, arg, handle) 507 timeout_t *ftn; 508 void *arg; 509 struct callout_handle handle; 510 { 511 struct callout_cpu *cc; 512 513 /* 514 * Check for a handle that was initialized 515 * by callout_handle_init, but never used 516 * for a real timeout. 517 */ 518 if (handle.callout == NULL) 519 return; 520 521 cc = callout_lock(handle.callout); 522 if (handle.callout->c_func == ftn && handle.callout->c_arg == arg) 523 callout_stop(handle.callout); 524 CC_UNLOCK(cc); 525 } 526 527 void 528 callout_handle_init(struct callout_handle *handle) 529 { 530 handle->callout = NULL; 531 } 532 533 /* 534 * New interface; clients allocate their own callout structures. 535 * 536 * callout_reset() - establish or change a timeout 537 * callout_stop() - disestablish a timeout 538 * callout_init() - initialize a callout structure so that it can 539 * safely be passed to callout_reset() and callout_stop() 540 * 541 * <sys/callout.h> defines three convenience macros: 542 * 543 * callout_active() - returns truth if callout has not been stopped, 544 * drained, or deactivated since the last time the callout was 545 * reset. 546 * callout_pending() - returns truth if callout is still waiting for timeout 547 * callout_deactivate() - marks the callout as having been serviced 548 */ 549 int 550 callout_reset_on(struct callout *c, int to_ticks, void (*ftn)(void *), 551 void *arg, int cpu) 552 { 553 struct callout_cpu *cc; 554 int cancelled = 0; 555 556 /* 557 * Don't allow migration of pre-allocated callouts lest they 558 * become unbalanced. 559 */ 560 if (c->c_flags & CALLOUT_LOCAL_ALLOC) 561 cpu = c->c_cpu; 562 retry: 563 cc = callout_lock(c); 564 if (cc->cc_curr == c) { 565 /* 566 * We're being asked to reschedule a callout which is 567 * currently in progress. If there is a lock then we 568 * can cancel the callout if it has not really started. 569 */ 570 if (c->c_lock != NULL && !cc->cc_cancel) 571 cancelled = cc->cc_cancel = 1; 572 if (cc->cc_waiting) { 573 /* 574 * Someone has called callout_drain to kill this 575 * callout. Don't reschedule. 576 */ 577 CTR4(KTR_CALLOUT, "%s %p func %p arg %p", 578 cancelled ? "cancelled" : "failed to cancel", 579 c, c->c_func, c->c_arg); 580 CC_UNLOCK(cc); 581 return (cancelled); 582 } 583 } 584 if (c->c_flags & CALLOUT_PENDING) { 585 if (cc->cc_next == c) { 586 cc->cc_next = TAILQ_NEXT(c, c_links.tqe); 587 } 588 TAILQ_REMOVE(&cc->cc_callwheel[c->c_time & callwheelmask], c, 589 c_links.tqe); 590 591 cancelled = 1; 592 c->c_flags &= ~(CALLOUT_ACTIVE | CALLOUT_PENDING); 593 } 594 /* 595 * If the lock must migrate we have to check the state again as 596 * we can't hold both the new and old locks simultaneously. 597 */ 598 if (c->c_cpu != cpu) { 599 c->c_cpu = cpu; 600 CC_UNLOCK(cc); 601 goto retry; 602 } 603 604 if (to_ticks <= 0) 605 to_ticks = 1; 606 607 c->c_arg = arg; 608 c->c_flags |= (CALLOUT_ACTIVE | CALLOUT_PENDING); 609 c->c_func = ftn; 610 c->c_time = ticks + to_ticks; 611 TAILQ_INSERT_TAIL(&cc->cc_callwheel[c->c_time & callwheelmask], 612 c, c_links.tqe); 613 CTR5(KTR_CALLOUT, "%sscheduled %p func %p arg %p in %d", 614 cancelled ? "re" : "", c, c->c_func, c->c_arg, to_ticks); 615 CC_UNLOCK(cc); 616 617 return (cancelled); 618 } 619 620 /* 621 * Common idioms that can be optimized in the future. 622 */ 623 int 624 callout_schedule_on(struct callout *c, int to_ticks, int cpu) 625 { 626 return callout_reset_on(c, to_ticks, c->c_func, c->c_arg, cpu); 627 } 628 629 int 630 callout_schedule(struct callout *c, int to_ticks) 631 { 632 return callout_reset_on(c, to_ticks, c->c_func, c->c_arg, c->c_cpu); 633 } 634 635 int 636 _callout_stop_safe(c, safe) 637 struct callout *c; 638 int safe; 639 { 640 struct callout_cpu *cc; 641 struct lock_class *class; 642 int use_lock, sq_locked; 643 644 /* 645 * Some old subsystems don't hold Giant while running a callout_stop(), 646 * so just discard this check for the moment. 647 */ 648 if (!safe && c->c_lock != NULL) { 649 if (c->c_lock == &Giant.lock_object) 650 use_lock = mtx_owned(&Giant); 651 else { 652 use_lock = 1; 653 class = LOCK_CLASS(c->c_lock); 654 class->lc_assert(c->c_lock, LA_XLOCKED); 655 } 656 } else 657 use_lock = 0; 658 659 sq_locked = 0; 660 again: 661 cc = callout_lock(c); 662 /* 663 * If the callout isn't pending, it's not on the queue, so 664 * don't attempt to remove it from the queue. We can try to 665 * stop it by other means however. 666 */ 667 if (!(c->c_flags & CALLOUT_PENDING)) { 668 c->c_flags &= ~CALLOUT_ACTIVE; 669 670 /* 671 * If it wasn't on the queue and it isn't the current 672 * callout, then we can't stop it, so just bail. 673 */ 674 if (cc->cc_curr != c) { 675 CTR3(KTR_CALLOUT, "failed to stop %p func %p arg %p", 676 c, c->c_func, c->c_arg); 677 CC_UNLOCK(cc); 678 if (sq_locked) 679 sleepq_release(&cc->cc_waiting); 680 return (0); 681 } 682 683 if (safe) { 684 /* 685 * The current callout is running (or just 686 * about to run) and blocking is allowed, so 687 * just wait for the current invocation to 688 * finish. 689 */ 690 while (cc->cc_curr == c) { 691 692 /* 693 * Use direct calls to sleepqueue interface 694 * instead of cv/msleep in order to avoid 695 * a LOR between cc_lock and sleepqueue 696 * chain spinlocks. This piece of code 697 * emulates a msleep_spin() call actually. 698 * 699 * If we already have the sleepqueue chain 700 * locked, then we can safely block. If we 701 * don't already have it locked, however, 702 * we have to drop the cc_lock to lock 703 * it. This opens several races, so we 704 * restart at the beginning once we have 705 * both locks. If nothing has changed, then 706 * we will end up back here with sq_locked 707 * set. 708 */ 709 if (!sq_locked) { 710 CC_UNLOCK(cc); 711 sleepq_lock(&cc->cc_waiting); 712 sq_locked = 1; 713 goto again; 714 } 715 cc->cc_waiting = 1; 716 DROP_GIANT(); 717 CC_UNLOCK(cc); 718 sleepq_add(&cc->cc_waiting, 719 &cc->cc_lock.lock_object, "codrain", 720 SLEEPQ_SLEEP, 0); 721 sleepq_wait(&cc->cc_waiting, 0); 722 sq_locked = 0; 723 724 /* Reacquire locks previously released. */ 725 PICKUP_GIANT(); 726 CC_LOCK(cc); 727 } 728 } else if (use_lock && !cc->cc_cancel) { 729 /* 730 * The current callout is waiting for its 731 * lock which we hold. Cancel the callout 732 * and return. After our caller drops the 733 * lock, the callout will be skipped in 734 * softclock(). 735 */ 736 cc->cc_cancel = 1; 737 CTR3(KTR_CALLOUT, "cancelled %p func %p arg %p", 738 c, c->c_func, c->c_arg); 739 CC_UNLOCK(cc); 740 KASSERT(!sq_locked, ("sleepqueue chain locked")); 741 return (1); 742 } 743 CTR3(KTR_CALLOUT, "failed to stop %p func %p arg %p", 744 c, c->c_func, c->c_arg); 745 CC_UNLOCK(cc); 746 KASSERT(!sq_locked, ("sleepqueue chain still locked")); 747 return (0); 748 } 749 if (sq_locked) 750 sleepq_release(&cc->cc_waiting); 751 752 c->c_flags &= ~(CALLOUT_ACTIVE | CALLOUT_PENDING); 753 754 if (cc->cc_next == c) { 755 cc->cc_next = TAILQ_NEXT(c, c_links.tqe); 756 } 757 TAILQ_REMOVE(&cc->cc_callwheel[c->c_time & callwheelmask], c, 758 c_links.tqe); 759 760 CTR3(KTR_CALLOUT, "cancelled %p func %p arg %p", 761 c, c->c_func, c->c_arg); 762 763 if (c->c_flags & CALLOUT_LOCAL_ALLOC) { 764 c->c_func = NULL; 765 SLIST_INSERT_HEAD(&cc->cc_callfree, c, c_links.sle); 766 } 767 CC_UNLOCK(cc); 768 return (1); 769 } 770 771 void 772 callout_init(c, mpsafe) 773 struct callout *c; 774 int mpsafe; 775 { 776 bzero(c, sizeof *c); 777 if (mpsafe) { 778 c->c_lock = NULL; 779 c->c_flags = CALLOUT_RETURNUNLOCKED; 780 } else { 781 c->c_lock = &Giant.lock_object; 782 c->c_flags = 0; 783 } 784 c->c_cpu = timeout_cpu; 785 } 786 787 void 788 _callout_init_lock(c, lock, flags) 789 struct callout *c; 790 struct lock_object *lock; 791 int flags; 792 { 793 bzero(c, sizeof *c); 794 c->c_lock = lock; 795 KASSERT((flags & ~(CALLOUT_RETURNUNLOCKED | CALLOUT_SHAREDLOCK)) == 0, 796 ("callout_init_lock: bad flags %d", flags)); 797 KASSERT(lock != NULL || (flags & CALLOUT_RETURNUNLOCKED) == 0, 798 ("callout_init_lock: CALLOUT_RETURNUNLOCKED with no lock")); 799 KASSERT(lock == NULL || !(LOCK_CLASS(lock)->lc_flags & 800 (LC_SPINLOCK | LC_SLEEPABLE)), ("%s: invalid lock class", 801 __func__)); 802 c->c_flags = flags & (CALLOUT_RETURNUNLOCKED | CALLOUT_SHAREDLOCK); 803 c->c_cpu = timeout_cpu; 804 } 805 806 #ifdef APM_FIXUP_CALLTODO 807 /* 808 * Adjust the kernel calltodo timeout list. This routine is used after 809 * an APM resume to recalculate the calltodo timer list values with the 810 * number of hz's we have been sleeping. The next hardclock() will detect 811 * that there are fired timers and run softclock() to execute them. 812 * 813 * Please note, I have not done an exhaustive analysis of what code this 814 * might break. I am motivated to have my select()'s and alarm()'s that 815 * have expired during suspend firing upon resume so that the applications 816 * which set the timer can do the maintanence the timer was for as close 817 * as possible to the originally intended time. Testing this code for a 818 * week showed that resuming from a suspend resulted in 22 to 25 timers 819 * firing, which seemed independant on whether the suspend was 2 hours or 820 * 2 days. Your milage may vary. - Ken Key <key@cs.utk.edu> 821 */ 822 void 823 adjust_timeout_calltodo(time_change) 824 struct timeval *time_change; 825 { 826 register struct callout *p; 827 unsigned long delta_ticks; 828 829 /* 830 * How many ticks were we asleep? 831 * (stolen from tvtohz()). 832 */ 833 834 /* Don't do anything */ 835 if (time_change->tv_sec < 0) 836 return; 837 else if (time_change->tv_sec <= LONG_MAX / 1000000) 838 delta_ticks = (time_change->tv_sec * 1000000 + 839 time_change->tv_usec + (tick - 1)) / tick + 1; 840 else if (time_change->tv_sec <= LONG_MAX / hz) 841 delta_ticks = time_change->tv_sec * hz + 842 (time_change->tv_usec + (tick - 1)) / tick + 1; 843 else 844 delta_ticks = LONG_MAX; 845 846 if (delta_ticks > INT_MAX) 847 delta_ticks = INT_MAX; 848 849 /* 850 * Now rip through the timer calltodo list looking for timers 851 * to expire. 852 */ 853 854 /* don't collide with softclock() */ 855 CC_LOCK(cc); 856 for (p = calltodo.c_next; p != NULL; p = p->c_next) { 857 p->c_time -= delta_ticks; 858 859 /* Break if the timer had more time on it than delta_ticks */ 860 if (p->c_time > 0) 861 break; 862 863 /* take back the ticks the timer didn't use (p->c_time <= 0) */ 864 delta_ticks = -p->c_time; 865 } 866 CC_UNLOCK(cc); 867 868 return; 869 } 870 #endif /* APM_FIXUP_CALLTODO */ 871