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 int need_softclock = 0; 226 struct callout_cpu *cc; 227 228 /* 229 * Process callouts at a very low cpu priority, so we don't keep the 230 * relatively high clock interrupt priority any longer than necessary. 231 */ 232 cc = CC_SELF(); 233 mtx_lock_spin_flags(&cc->cc_lock, MTX_QUIET); 234 if (!TAILQ_EMPTY(&cc->cc_callwheel[ticks & callwheelmask])) { 235 need_softclock = 1; 236 } else if (cc->cc_softticks + 1 == ticks) 237 ++cc->cc_softticks; 238 mtx_unlock_spin_flags(&cc->cc_lock, MTX_QUIET); 239 /* 240 * swi_sched acquires the thread lock, so we don't want to call it 241 * with cc_lock held; incorrect locking order. 242 */ 243 if (need_softclock) 244 swi_sched(cc->cc_cookie, 0); 245 } 246 247 static struct callout_cpu * 248 callout_lock(struct callout *c) 249 { 250 struct callout_cpu *cc; 251 int cpu; 252 253 for (;;) { 254 cpu = c->c_cpu; 255 cc = CC_CPU(cpu); 256 CC_LOCK(cc); 257 if (cpu == c->c_cpu) 258 break; 259 CC_UNLOCK(cc); 260 } 261 return (cc); 262 } 263 264 /* 265 * The callout mechanism is based on the work of Adam M. Costello and 266 * George Varghese, published in a technical report entitled "Redesigning 267 * the BSD Callout and Timer Facilities" and modified slightly for inclusion 268 * in FreeBSD by Justin T. Gibbs. The original work on the data structures 269 * used in this implementation was published by G. Varghese and T. Lauck in 270 * the paper "Hashed and Hierarchical Timing Wheels: Data Structures for 271 * the Efficient Implementation of a Timer Facility" in the Proceedings of 272 * the 11th ACM Annual Symposium on Operating Systems Principles, 273 * Austin, Texas Nov 1987. 274 */ 275 276 /* 277 * Software (low priority) clock interrupt. 278 * Run periodic events from timeout queue. 279 */ 280 void 281 softclock(void *arg) 282 { 283 struct callout_cpu *cc; 284 struct callout *c; 285 struct callout_tailq *bucket; 286 int curticks; 287 int steps; /* #steps since we last allowed interrupts */ 288 int depth; 289 int mpcalls; 290 int lockcalls; 291 int gcalls; 292 #ifdef DIAGNOSTIC 293 struct bintime bt1, bt2; 294 struct timespec ts2; 295 static uint64_t maxdt = 36893488147419102LL; /* 2 msec */ 296 static timeout_t *lastfunc; 297 #endif 298 299 #ifndef MAX_SOFTCLOCK_STEPS 300 #define MAX_SOFTCLOCK_STEPS 100 /* Maximum allowed value of steps. */ 301 #endif /* MAX_SOFTCLOCK_STEPS */ 302 303 mpcalls = 0; 304 lockcalls = 0; 305 gcalls = 0; 306 depth = 0; 307 steps = 0; 308 cc = (struct callout_cpu *)arg; 309 CC_LOCK(cc); 310 while (cc->cc_softticks != ticks) { 311 cc->cc_softticks++; 312 /* 313 * cc_softticks may be modified by hard clock, so cache 314 * it while we work on a given bucket. 315 */ 316 curticks = cc->cc_softticks; 317 bucket = &cc->cc_callwheel[curticks & callwheelmask]; 318 c = TAILQ_FIRST(bucket); 319 while (c) { 320 depth++; 321 if (c->c_time != curticks) { 322 c = TAILQ_NEXT(c, c_links.tqe); 323 ++steps; 324 if (steps >= MAX_SOFTCLOCK_STEPS) { 325 cc->cc_next = c; 326 /* Give interrupts a chance. */ 327 CC_UNLOCK(cc); 328 ; /* nothing */ 329 CC_LOCK(cc); 330 c = cc->cc_next; 331 steps = 0; 332 } 333 } else { 334 void (*c_func)(void *); 335 void *c_arg; 336 struct lock_class *class; 337 struct lock_object *c_lock; 338 int c_flags, sharedlock; 339 340 cc->cc_next = TAILQ_NEXT(c, c_links.tqe); 341 TAILQ_REMOVE(bucket, c, c_links.tqe); 342 class = (c->c_lock != NULL) ? 343 LOCK_CLASS(c->c_lock) : NULL; 344 sharedlock = (c->c_flags & CALLOUT_SHAREDLOCK) ? 345 0 : 1; 346 c_lock = c->c_lock; 347 c_func = c->c_func; 348 c_arg = c->c_arg; 349 c_flags = c->c_flags; 350 if (c->c_flags & CALLOUT_LOCAL_ALLOC) { 351 c->c_flags = CALLOUT_LOCAL_ALLOC; 352 } else { 353 c->c_flags = 354 (c->c_flags & ~CALLOUT_PENDING); 355 } 356 cc->cc_curr = c; 357 cc->cc_cancel = 0; 358 CC_UNLOCK(cc); 359 if (c_lock != NULL) { 360 class->lc_lock(c_lock, sharedlock); 361 /* 362 * The callout may have been cancelled 363 * while we switched locks. 364 */ 365 if (cc->cc_cancel) { 366 class->lc_unlock(c_lock); 367 goto skip; 368 } 369 /* The callout cannot be stopped now. */ 370 cc->cc_cancel = 1; 371 372 if (c_lock == &Giant.lock_object) { 373 gcalls++; 374 CTR3(KTR_CALLOUT, 375 "callout %p func %p arg %p", 376 c, c_func, c_arg); 377 } else { 378 lockcalls++; 379 CTR3(KTR_CALLOUT, "callout lock" 380 " %p func %p arg %p", 381 c, c_func, c_arg); 382 } 383 } else { 384 mpcalls++; 385 CTR3(KTR_CALLOUT, 386 "callout mpsafe %p func %p arg %p", 387 c, c_func, c_arg); 388 } 389 #ifdef DIAGNOSTIC 390 binuptime(&bt1); 391 #endif 392 THREAD_NO_SLEEPING(); 393 c_func(c_arg); 394 THREAD_SLEEPING_OK(); 395 #ifdef DIAGNOSTIC 396 binuptime(&bt2); 397 bintime_sub(&bt2, &bt1); 398 if (bt2.frac > maxdt) { 399 if (lastfunc != c_func || 400 bt2.frac > maxdt * 2) { 401 bintime2timespec(&bt2, &ts2); 402 printf( 403 "Expensive timeout(9) function: %p(%p) %jd.%09ld s\n", 404 c_func, c_arg, 405 (intmax_t)ts2.tv_sec, 406 ts2.tv_nsec); 407 } 408 maxdt = bt2.frac; 409 lastfunc = c_func; 410 } 411 #endif 412 if ((c_flags & CALLOUT_RETURNUNLOCKED) == 0) 413 class->lc_unlock(c_lock); 414 skip: 415 CC_LOCK(cc); 416 /* 417 * If the current callout is locally 418 * allocated (from timeout(9)) 419 * then put it on the freelist. 420 * 421 * Note: we need to check the cached 422 * copy of c_flags because if it was not 423 * local, then it's not safe to deref the 424 * callout pointer. 425 */ 426 if (c_flags & CALLOUT_LOCAL_ALLOC) { 427 KASSERT(c->c_flags == 428 CALLOUT_LOCAL_ALLOC, 429 ("corrupted callout")); 430 c->c_func = NULL; 431 SLIST_INSERT_HEAD(&cc->cc_callfree, c, 432 c_links.sle); 433 } 434 cc->cc_curr = NULL; 435 if (cc->cc_waiting) { 436 /* 437 * There is someone waiting 438 * for the callout to complete. 439 */ 440 cc->cc_waiting = 0; 441 CC_UNLOCK(cc); 442 wakeup(&cc->cc_waiting); 443 CC_LOCK(cc); 444 } 445 steps = 0; 446 c = cc->cc_next; 447 } 448 } 449 } 450 avg_depth += (depth * 1000 - avg_depth) >> 8; 451 avg_mpcalls += (mpcalls * 1000 - avg_mpcalls) >> 8; 452 avg_lockcalls += (lockcalls * 1000 - avg_lockcalls) >> 8; 453 avg_gcalls += (gcalls * 1000 - avg_gcalls) >> 8; 454 cc->cc_next = NULL; 455 CC_UNLOCK(cc); 456 } 457 458 /* 459 * timeout -- 460 * Execute a function after a specified length of time. 461 * 462 * untimeout -- 463 * Cancel previous timeout function call. 464 * 465 * callout_handle_init -- 466 * Initialize a handle so that using it with untimeout is benign. 467 * 468 * See AT&T BCI Driver Reference Manual for specification. This 469 * implementation differs from that one in that although an 470 * identification value is returned from timeout, the original 471 * arguments to timeout as well as the identifier are used to 472 * identify entries for untimeout. 473 */ 474 struct callout_handle 475 timeout(ftn, arg, to_ticks) 476 timeout_t *ftn; 477 void *arg; 478 int to_ticks; 479 { 480 struct callout_cpu *cc; 481 struct callout *new; 482 struct callout_handle handle; 483 484 cc = CC_CPU(timeout_cpu); 485 CC_LOCK(cc); 486 /* Fill in the next free callout structure. */ 487 new = SLIST_FIRST(&cc->cc_callfree); 488 if (new == NULL) 489 /* XXX Attempt to malloc first */ 490 panic("timeout table full"); 491 SLIST_REMOVE_HEAD(&cc->cc_callfree, c_links.sle); 492 callout_reset(new, to_ticks, ftn, arg); 493 handle.callout = new; 494 CC_UNLOCK(cc); 495 496 return (handle); 497 } 498 499 void 500 untimeout(ftn, arg, handle) 501 timeout_t *ftn; 502 void *arg; 503 struct callout_handle handle; 504 { 505 struct callout_cpu *cc; 506 507 /* 508 * Check for a handle that was initialized 509 * by callout_handle_init, but never used 510 * for a real timeout. 511 */ 512 if (handle.callout == NULL) 513 return; 514 515 cc = callout_lock(handle.callout); 516 if (handle.callout->c_func == ftn && handle.callout->c_arg == arg) 517 callout_stop(handle.callout); 518 CC_UNLOCK(cc); 519 } 520 521 void 522 callout_handle_init(struct callout_handle *handle) 523 { 524 handle->callout = NULL; 525 } 526 527 /* 528 * New interface; clients allocate their own callout structures. 529 * 530 * callout_reset() - establish or change a timeout 531 * callout_stop() - disestablish a timeout 532 * callout_init() - initialize a callout structure so that it can 533 * safely be passed to callout_reset() and callout_stop() 534 * 535 * <sys/callout.h> defines three convenience macros: 536 * 537 * callout_active() - returns truth if callout has not been stopped, 538 * drained, or deactivated since the last time the callout was 539 * reset. 540 * callout_pending() - returns truth if callout is still waiting for timeout 541 * callout_deactivate() - marks the callout as having been serviced 542 */ 543 int 544 callout_reset_on(struct callout *c, int to_ticks, void (*ftn)(void *), 545 void *arg, int cpu) 546 { 547 struct callout_cpu *cc; 548 int cancelled = 0; 549 550 /* 551 * Don't allow migration of pre-allocated callouts lest they 552 * become unbalanced. 553 */ 554 if (c->c_flags & CALLOUT_LOCAL_ALLOC) 555 cpu = c->c_cpu; 556 retry: 557 cc = callout_lock(c); 558 if (cc->cc_curr == c) { 559 /* 560 * We're being asked to reschedule a callout which is 561 * currently in progress. If there is a lock then we 562 * can cancel the callout if it has not really started. 563 */ 564 if (c->c_lock != NULL && !cc->cc_cancel) 565 cancelled = cc->cc_cancel = 1; 566 if (cc->cc_waiting) { 567 /* 568 * Someone has called callout_drain to kill this 569 * callout. Don't reschedule. 570 */ 571 CTR4(KTR_CALLOUT, "%s %p func %p arg %p", 572 cancelled ? "cancelled" : "failed to cancel", 573 c, c->c_func, c->c_arg); 574 CC_UNLOCK(cc); 575 return (cancelled); 576 } 577 } 578 if (c->c_flags & CALLOUT_PENDING) { 579 if (cc->cc_next == c) { 580 cc->cc_next = TAILQ_NEXT(c, c_links.tqe); 581 } 582 TAILQ_REMOVE(&cc->cc_callwheel[c->c_time & callwheelmask], c, 583 c_links.tqe); 584 585 cancelled = 1; 586 c->c_flags &= ~(CALLOUT_ACTIVE | CALLOUT_PENDING); 587 } 588 /* 589 * If the lock must migrate we have to check the state again as 590 * we can't hold both the new and old locks simultaneously. 591 */ 592 if (c->c_cpu != cpu) { 593 c->c_cpu = cpu; 594 CC_UNLOCK(cc); 595 goto retry; 596 } 597 598 if (to_ticks <= 0) 599 to_ticks = 1; 600 601 c->c_arg = arg; 602 c->c_flags |= (CALLOUT_ACTIVE | CALLOUT_PENDING); 603 c->c_func = ftn; 604 c->c_time = ticks + to_ticks; 605 TAILQ_INSERT_TAIL(&cc->cc_callwheel[c->c_time & callwheelmask], 606 c, c_links.tqe); 607 CTR5(KTR_CALLOUT, "%sscheduled %p func %p arg %p in %d", 608 cancelled ? "re" : "", c, c->c_func, c->c_arg, to_ticks); 609 CC_UNLOCK(cc); 610 611 return (cancelled); 612 } 613 614 int 615 _callout_stop_safe(c, safe) 616 struct callout *c; 617 int safe; 618 { 619 struct callout_cpu *cc; 620 struct lock_class *class; 621 int use_lock, sq_locked; 622 623 /* 624 * Some old subsystems don't hold Giant while running a callout_stop(), 625 * so just discard this check for the moment. 626 */ 627 if (!safe && c->c_lock != NULL) { 628 if (c->c_lock == &Giant.lock_object) 629 use_lock = mtx_owned(&Giant); 630 else { 631 use_lock = 1; 632 class = LOCK_CLASS(c->c_lock); 633 class->lc_assert(c->c_lock, LA_XLOCKED); 634 } 635 } else 636 use_lock = 0; 637 638 sq_locked = 0; 639 again: 640 cc = callout_lock(c); 641 /* 642 * If the callout isn't pending, it's not on the queue, so 643 * don't attempt to remove it from the queue. We can try to 644 * stop it by other means however. 645 */ 646 if (!(c->c_flags & CALLOUT_PENDING)) { 647 c->c_flags &= ~CALLOUT_ACTIVE; 648 649 /* 650 * If it wasn't on the queue and it isn't the current 651 * callout, then we can't stop it, so just bail. 652 */ 653 if (cc->cc_curr != c) { 654 CTR3(KTR_CALLOUT, "failed to stop %p func %p arg %p", 655 c, c->c_func, c->c_arg); 656 CC_UNLOCK(cc); 657 if (sq_locked) 658 sleepq_release(&cc->cc_waiting); 659 return (0); 660 } 661 662 if (safe) { 663 /* 664 * The current callout is running (or just 665 * about to run) and blocking is allowed, so 666 * just wait for the current invocation to 667 * finish. 668 */ 669 while (cc->cc_curr == c) { 670 671 /* 672 * Use direct calls to sleepqueue interface 673 * instead of cv/msleep in order to avoid 674 * a LOR between cc_lock and sleepqueue 675 * chain spinlocks. This piece of code 676 * emulates a msleep_spin() call actually. 677 * 678 * If we already have the sleepqueue chain 679 * locked, then we can safely block. If we 680 * don't already have it locked, however, 681 * we have to drop the cc_lock to lock 682 * it. This opens several races, so we 683 * restart at the beginning once we have 684 * both locks. If nothing has changed, then 685 * we will end up back here with sq_locked 686 * set. 687 */ 688 if (!sq_locked) { 689 CC_UNLOCK(cc); 690 sleepq_lock(&cc->cc_waiting); 691 sq_locked = 1; 692 goto again; 693 } 694 cc->cc_waiting = 1; 695 DROP_GIANT(); 696 CC_UNLOCK(cc); 697 sleepq_add(&cc->cc_waiting, 698 &cc->cc_lock.lock_object, "codrain", 699 SLEEPQ_SLEEP, 0); 700 sleepq_wait(&cc->cc_waiting, 0); 701 sq_locked = 0; 702 703 /* Reacquire locks previously released. */ 704 PICKUP_GIANT(); 705 CC_LOCK(cc); 706 } 707 } else if (use_lock && !cc->cc_cancel) { 708 /* 709 * The current callout is waiting for its 710 * lock which we hold. Cancel the callout 711 * and return. After our caller drops the 712 * lock, the callout will be skipped in 713 * softclock(). 714 */ 715 cc->cc_cancel = 1; 716 CTR3(KTR_CALLOUT, "cancelled %p func %p arg %p", 717 c, c->c_func, c->c_arg); 718 CC_UNLOCK(cc); 719 KASSERT(!sq_locked, ("sleepqueue chain locked")); 720 return (1); 721 } 722 CTR3(KTR_CALLOUT, "failed to stop %p func %p arg %p", 723 c, c->c_func, c->c_arg); 724 CC_UNLOCK(cc); 725 KASSERT(!sq_locked, ("sleepqueue chain still locked")); 726 return (0); 727 } 728 if (sq_locked) 729 sleepq_release(&cc->cc_waiting); 730 731 c->c_flags &= ~(CALLOUT_ACTIVE | CALLOUT_PENDING); 732 733 if (cc->cc_next == c) { 734 cc->cc_next = TAILQ_NEXT(c, c_links.tqe); 735 } 736 TAILQ_REMOVE(&cc->cc_callwheel[c->c_time & callwheelmask], c, 737 c_links.tqe); 738 739 CTR3(KTR_CALLOUT, "cancelled %p func %p arg %p", 740 c, c->c_func, c->c_arg); 741 742 if (c->c_flags & CALLOUT_LOCAL_ALLOC) { 743 c->c_func = NULL; 744 SLIST_INSERT_HEAD(&cc->cc_callfree, c, c_links.sle); 745 } 746 CC_UNLOCK(cc); 747 return (1); 748 } 749 750 void 751 callout_init(c, mpsafe) 752 struct callout *c; 753 int mpsafe; 754 { 755 bzero(c, sizeof *c); 756 if (mpsafe) { 757 c->c_lock = NULL; 758 c->c_flags = CALLOUT_RETURNUNLOCKED; 759 } else { 760 c->c_lock = &Giant.lock_object; 761 c->c_flags = 0; 762 } 763 c->c_cpu = timeout_cpu; 764 } 765 766 void 767 _callout_init_lock(c, lock, flags) 768 struct callout *c; 769 struct lock_object *lock; 770 int flags; 771 { 772 bzero(c, sizeof *c); 773 c->c_lock = lock; 774 KASSERT((flags & ~(CALLOUT_RETURNUNLOCKED | CALLOUT_SHAREDLOCK)) == 0, 775 ("callout_init_lock: bad flags %d", flags)); 776 KASSERT(lock != NULL || (flags & CALLOUT_RETURNUNLOCKED) == 0, 777 ("callout_init_lock: CALLOUT_RETURNUNLOCKED with no lock")); 778 KASSERT(lock == NULL || !(LOCK_CLASS(lock)->lc_flags & 779 (LC_SPINLOCK | LC_SLEEPABLE)), ("%s: invalid lock class", 780 __func__)); 781 c->c_flags = flags & (CALLOUT_RETURNUNLOCKED | CALLOUT_SHAREDLOCK); 782 c->c_cpu = timeout_cpu; 783 } 784 785 #ifdef APM_FIXUP_CALLTODO 786 /* 787 * Adjust the kernel calltodo timeout list. This routine is used after 788 * an APM resume to recalculate the calltodo timer list values with the 789 * number of hz's we have been sleeping. The next hardclock() will detect 790 * that there are fired timers and run softclock() to execute them. 791 * 792 * Please note, I have not done an exhaustive analysis of what code this 793 * might break. I am motivated to have my select()'s and alarm()'s that 794 * have expired during suspend firing upon resume so that the applications 795 * which set the timer can do the maintanence the timer was for as close 796 * as possible to the originally intended time. Testing this code for a 797 * week showed that resuming from a suspend resulted in 22 to 25 timers 798 * firing, which seemed independant on whether the suspend was 2 hours or 799 * 2 days. Your milage may vary. - Ken Key <key@cs.utk.edu> 800 */ 801 void 802 adjust_timeout_calltodo(time_change) 803 struct timeval *time_change; 804 { 805 register struct callout *p; 806 unsigned long delta_ticks; 807 808 /* 809 * How many ticks were we asleep? 810 * (stolen from tvtohz()). 811 */ 812 813 /* Don't do anything */ 814 if (time_change->tv_sec < 0) 815 return; 816 else if (time_change->tv_sec <= LONG_MAX / 1000000) 817 delta_ticks = (time_change->tv_sec * 1000000 + 818 time_change->tv_usec + (tick - 1)) / tick + 1; 819 else if (time_change->tv_sec <= LONG_MAX / hz) 820 delta_ticks = time_change->tv_sec * hz + 821 (time_change->tv_usec + (tick - 1)) / tick + 1; 822 else 823 delta_ticks = LONG_MAX; 824 825 if (delta_ticks > INT_MAX) 826 delta_ticks = INT_MAX; 827 828 /* 829 * Now rip through the timer calltodo list looking for timers 830 * to expire. 831 */ 832 833 /* don't collide with softclock() */ 834 CC_LOCK(cc); 835 for (p = calltodo.c_next; p != NULL; p = p->c_next) { 836 p->c_time -= delta_ticks; 837 838 /* Break if the timer had more time on it than delta_ticks */ 839 if (p->c_time > 0) 840 break; 841 842 /* take back the ticks the timer didn't use (p->c_time <= 0) */ 843 delta_ticks = -p->c_time; 844 } 845 CC_UNLOCK(cc); 846 847 return; 848 } 849 #endif /* APM_FIXUP_CALLTODO */ 850