Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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sys/kern/kern_timeout.c
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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: releng/10.3/sys/kern/kern_timeout.c 296913 2016-03-15 17:09:27Z kib $"); 39 40 #include "opt_callout_profiling.h" 41 #include "opt_kdtrace.h" 42 #if defined(__arm__) 43 #include "opt_timer.h" 44 #endif 45 46 #include <sys/param.h> 47 #include <sys/systm.h> 48 #include <sys/bus.h> 49 #include <sys/callout.h> 50 #include <sys/file.h> 51 #include <sys/interrupt.h> 52 #include <sys/kernel.h> 53 #include <sys/ktr.h> 54 #include <sys/lock.h> 55 #include <sys/malloc.h> 56 #include <sys/mutex.h> 57 #include <sys/proc.h> 58 #include <sys/sdt.h> 59 #include <sys/sleepqueue.h> 60 #include <sys/sysctl.h> 61 #include <sys/smp.h> 62 63 #ifdef SMP 64 #include <machine/cpu.h> 65 #endif 66 67 #ifndef NO_EVENTTIMERS 68 DPCPU_DECLARE(sbintime_t, hardclocktime); 69 #endif 70 71 SDT_PROVIDER_DEFINE(callout_execute); 72 SDT_PROBE_DEFINE1(callout_execute, kernel, , callout__start, 73 "struct callout *"); 74 SDT_PROBE_DEFINE1(callout_execute, kernel, , callout__end, 75 "struct callout *"); 76 77 #ifdef CALLOUT_PROFILING 78 static int avg_depth; 79 SYSCTL_INT(_debug, OID_AUTO, to_avg_depth, CTLFLAG_RD, &avg_depth, 0, 80 "Average number of items examined per softclock call. Units = 1/1000"); 81 static int avg_gcalls; 82 SYSCTL_INT(_debug, OID_AUTO, to_avg_gcalls, CTLFLAG_RD, &avg_gcalls, 0, 83 "Average number of Giant callouts made per softclock call. Units = 1/1000"); 84 static int avg_lockcalls; 85 SYSCTL_INT(_debug, OID_AUTO, to_avg_lockcalls, CTLFLAG_RD, &avg_lockcalls, 0, 86 "Average number of lock callouts made per softclock call. Units = 1/1000"); 87 static int avg_mpcalls; 88 SYSCTL_INT(_debug, OID_AUTO, to_avg_mpcalls, CTLFLAG_RD, &avg_mpcalls, 0, 89 "Average number of MP callouts made per softclock call. Units = 1/1000"); 90 static int avg_depth_dir; 91 SYSCTL_INT(_debug, OID_AUTO, to_avg_depth_dir, CTLFLAG_RD, &avg_depth_dir, 0, 92 "Average number of direct callouts examined per callout_process call. " 93 "Units = 1/1000"); 94 static int avg_lockcalls_dir; 95 SYSCTL_INT(_debug, OID_AUTO, to_avg_lockcalls_dir, CTLFLAG_RD, 96 &avg_lockcalls_dir, 0, "Average number of lock direct callouts made per " 97 "callout_process call. Units = 1/1000"); 98 static int avg_mpcalls_dir; 99 SYSCTL_INT(_debug, OID_AUTO, to_avg_mpcalls_dir, CTLFLAG_RD, &avg_mpcalls_dir, 100 0, "Average number of MP direct callouts made per callout_process call. " 101 "Units = 1/1000"); 102 #endif 103 104 static int ncallout; 105 SYSCTL_INT(_kern, OID_AUTO, ncallout, CTLFLAG_RDTUN, &ncallout, 0, 106 "Number of entries in callwheel and size of timeout() preallocation"); 107 108 /* 109 * TODO: 110 * allocate more timeout table slots when table overflows. 111 */ 112 u_int callwheelsize, callwheelmask; 113 114 /* 115 * The callout cpu exec entities represent informations necessary for 116 * describing the state of callouts currently running on the CPU and the ones 117 * necessary for migrating callouts to the new callout cpu. In particular, 118 * the first entry of the array cc_exec_entity holds informations for callout 119 * running in SWI thread context, while the second one holds informations 120 * for callout running directly from hardware interrupt context. 121 * The cached informations are very important for deferring migration when 122 * the migrating callout is already running. 123 */ 124 struct cc_exec { 125 struct callout *cc_curr; 126 #ifdef SMP 127 void (*ce_migration_func)(void *); 128 void *ce_migration_arg; 129 int ce_migration_cpu; 130 sbintime_t ce_migration_time; 131 sbintime_t ce_migration_prec; 132 #endif 133 bool cc_cancel; 134 bool cc_waiting; 135 }; 136 137 /* 138 * There is one struct callout_cpu per cpu, holding all relevant 139 * state for the callout processing thread on the individual CPU. 140 */ 141 struct callout_cpu { 142 struct mtx_padalign cc_lock; 143 struct cc_exec cc_exec_entity[2]; 144 struct callout *cc_next; 145 struct callout *cc_callout; 146 struct callout_list *cc_callwheel; 147 struct callout_tailq cc_expireq; 148 struct callout_slist cc_callfree; 149 sbintime_t cc_firstevent; 150 sbintime_t cc_lastscan; 151 void *cc_cookie; 152 u_int cc_bucket; 153 u_int cc_inited; 154 char cc_ktr_event_name[20]; 155 }; 156 157 #define callout_migrating(c) ((c)->c_iflags & CALLOUT_DFRMIGRATION) 158 159 #define cc_exec_curr(cc, dir) cc->cc_exec_entity[dir].cc_curr 160 #define cc_exec_next(cc) cc->cc_next 161 #define cc_exec_cancel(cc, dir) cc->cc_exec_entity[dir].cc_cancel 162 #define cc_exec_waiting(cc, dir) cc->cc_exec_entity[dir].cc_waiting 163 #ifdef SMP 164 #define cc_migration_func(cc, dir) cc->cc_exec_entity[dir].ce_migration_func 165 #define cc_migration_arg(cc, dir) cc->cc_exec_entity[dir].ce_migration_arg 166 #define cc_migration_cpu(cc, dir) cc->cc_exec_entity[dir].ce_migration_cpu 167 #define cc_migration_time(cc, dir) cc->cc_exec_entity[dir].ce_migration_time 168 #define cc_migration_prec(cc, dir) cc->cc_exec_entity[dir].ce_migration_prec 169 170 struct callout_cpu cc_cpu[MAXCPU]; 171 #define CPUBLOCK MAXCPU 172 #define CC_CPU(cpu) (&cc_cpu[(cpu)]) 173 #define CC_SELF() CC_CPU(PCPU_GET(cpuid)) 174 #else 175 struct callout_cpu cc_cpu; 176 #define CC_CPU(cpu) &cc_cpu 177 #define CC_SELF() &cc_cpu 178 #endif 179 #define CC_LOCK(cc) mtx_lock_spin(&(cc)->cc_lock) 180 #define CC_UNLOCK(cc) mtx_unlock_spin(&(cc)->cc_lock) 181 #define CC_LOCK_ASSERT(cc) mtx_assert(&(cc)->cc_lock, MA_OWNED) 182 183 static int timeout_cpu; 184 185 static void callout_cpu_init(struct callout_cpu *cc, int cpu); 186 static void softclock_call_cc(struct callout *c, struct callout_cpu *cc, 187 #ifdef CALLOUT_PROFILING 188 int *mpcalls, int *lockcalls, int *gcalls, 189 #endif 190 int direct); 191 192 static MALLOC_DEFINE(M_CALLOUT, "callout", "Callout datastructures"); 193 194 /** 195 * Locked by cc_lock: 196 * cc_curr - If a callout is in progress, it is cc_curr. 197 * If cc_curr is non-NULL, threads waiting in 198 * callout_drain() will be woken up as soon as the 199 * relevant callout completes. 200 * cc_cancel - Changing to 1 with both callout_lock and cc_lock held 201 * guarantees that the current callout will not run. 202 * The softclock() function sets this to 0 before it 203 * drops callout_lock to acquire c_lock, and it calls 204 * the handler only if curr_cancelled is still 0 after 205 * cc_lock is successfully acquired. 206 * cc_waiting - If a thread is waiting in callout_drain(), then 207 * callout_wait is nonzero. Set only when 208 * cc_curr is non-NULL. 209 */ 210 211 /* 212 * Resets the execution entity tied to a specific callout cpu. 213 */ 214 static void 215 cc_cce_cleanup(struct callout_cpu *cc, int direct) 216 { 217 218 cc_exec_curr(cc, direct) = NULL; 219 cc_exec_cancel(cc, direct) = false; 220 cc_exec_waiting(cc, direct) = false; 221 #ifdef SMP 222 cc_migration_cpu(cc, direct) = CPUBLOCK; 223 cc_migration_time(cc, direct) = 0; 224 cc_migration_prec(cc, direct) = 0; 225 cc_migration_func(cc, direct) = NULL; 226 cc_migration_arg(cc, direct) = NULL; 227 #endif 228 } 229 230 /* 231 * Checks if migration is requested by a specific callout cpu. 232 */ 233 static int 234 cc_cce_migrating(struct callout_cpu *cc, int direct) 235 { 236 237 #ifdef SMP 238 return (cc_migration_cpu(cc, direct) != CPUBLOCK); 239 #else 240 return (0); 241 #endif 242 } 243 244 /* 245 * Kernel low level callwheel initialization 246 * called on cpu0 during kernel startup. 247 */ 248 static void 249 callout_callwheel_init(void *dummy) 250 { 251 struct callout_cpu *cc; 252 253 /* 254 * Calculate the size of the callout wheel and the preallocated 255 * timeout() structures. 256 * XXX: Clip callout to result of previous function of maxusers 257 * maximum 384. This is still huge, but acceptable. 258 */ 259 memset(CC_CPU(0), 0, sizeof(cc_cpu)); 260 ncallout = imin(16 + maxproc + maxfiles, 18508); 261 TUNABLE_INT_FETCH("kern.ncallout", &ncallout); 262 263 /* 264 * Calculate callout wheel size, should be next power of two higher 265 * than 'ncallout'. 266 */ 267 callwheelsize = 1 << fls(ncallout); 268 callwheelmask = callwheelsize - 1; 269 270 /* 271 * Only cpu0 handles timeout(9) and receives a preallocation. 272 * 273 * XXX: Once all timeout(9) consumers are converted this can 274 * be removed. 275 */ 276 timeout_cpu = PCPU_GET(cpuid); 277 cc = CC_CPU(timeout_cpu); 278 cc->cc_callout = malloc(ncallout * sizeof(struct callout), 279 M_CALLOUT, M_WAITOK); 280 callout_cpu_init(cc, timeout_cpu); 281 } 282 SYSINIT(callwheel_init, SI_SUB_CPU, SI_ORDER_ANY, callout_callwheel_init, NULL); 283 284 /* 285 * Initialize the per-cpu callout structures. 286 */ 287 static void 288 callout_cpu_init(struct callout_cpu *cc, int cpu) 289 { 290 struct callout *c; 291 int i; 292 293 mtx_init(&cc->cc_lock, "callout", NULL, MTX_SPIN | MTX_RECURSE); 294 SLIST_INIT(&cc->cc_callfree); 295 cc->cc_inited = 1; 296 cc->cc_callwheel = malloc(sizeof(struct callout_list) * callwheelsize, 297 M_CALLOUT, M_WAITOK); 298 for (i = 0; i < callwheelsize; i++) 299 LIST_INIT(&cc->cc_callwheel[i]); 300 TAILQ_INIT(&cc->cc_expireq); 301 cc->cc_firstevent = INT64_MAX; 302 for (i = 0; i < 2; i++) 303 cc_cce_cleanup(cc, i); 304 snprintf(cc->cc_ktr_event_name, sizeof(cc->cc_ktr_event_name), 305 "callwheel cpu %d", cpu); 306 if (cc->cc_callout == NULL) /* Only cpu0 handles timeout(9) */ 307 return; 308 for (i = 0; i < ncallout; i++) { 309 c = &cc->cc_callout[i]; 310 callout_init(c, 0); 311 c->c_iflags = CALLOUT_LOCAL_ALLOC; 312 SLIST_INSERT_HEAD(&cc->cc_callfree, c, c_links.sle); 313 } 314 } 315 316 #ifdef SMP 317 /* 318 * Switches the cpu tied to a specific callout. 319 * The function expects a locked incoming callout cpu and returns with 320 * locked outcoming callout cpu. 321 */ 322 static struct callout_cpu * 323 callout_cpu_switch(struct callout *c, struct callout_cpu *cc, int new_cpu) 324 { 325 struct callout_cpu *new_cc; 326 327 MPASS(c != NULL && cc != NULL); 328 CC_LOCK_ASSERT(cc); 329 330 /* 331 * Avoid interrupts and preemption firing after the callout cpu 332 * is blocked in order to avoid deadlocks as the new thread 333 * may be willing to acquire the callout cpu lock. 334 */ 335 c->c_cpu = CPUBLOCK; 336 spinlock_enter(); 337 CC_UNLOCK(cc); 338 new_cc = CC_CPU(new_cpu); 339 CC_LOCK(new_cc); 340 spinlock_exit(); 341 c->c_cpu = new_cpu; 342 return (new_cc); 343 } 344 #endif 345 346 /* 347 * Start standard softclock thread. 348 */ 349 static void 350 start_softclock(void *dummy) 351 { 352 struct callout_cpu *cc; 353 #ifdef SMP 354 int cpu; 355 #endif 356 357 cc = CC_CPU(timeout_cpu); 358 if (swi_add(&clk_intr_event, "clock", softclock, cc, SWI_CLOCK, 359 INTR_MPSAFE, &cc->cc_cookie)) 360 panic("died while creating standard software ithreads"); 361 #ifdef SMP 362 CPU_FOREACH(cpu) { 363 if (cpu == timeout_cpu) 364 continue; 365 cc = CC_CPU(cpu); 366 cc->cc_callout = NULL; /* Only cpu0 handles timeout(9). */ 367 callout_cpu_init(cc, cpu); 368 if (swi_add(NULL, "clock", softclock, cc, SWI_CLOCK, 369 INTR_MPSAFE, &cc->cc_cookie)) 370 panic("died while creating standard software ithreads"); 371 } 372 #endif 373 } 374 SYSINIT(start_softclock, SI_SUB_SOFTINTR, SI_ORDER_FIRST, start_softclock, NULL); 375 376 #define CC_HASH_SHIFT 8 377 378 static inline u_int 379 callout_hash(sbintime_t sbt) 380 { 381 382 return (sbt >> (32 - CC_HASH_SHIFT)); 383 } 384 385 static inline u_int 386 callout_get_bucket(sbintime_t sbt) 387 { 388 389 return (callout_hash(sbt) & callwheelmask); 390 } 391 392 void 393 callout_process(sbintime_t now) 394 { 395 struct callout *tmp, *tmpn; 396 struct callout_cpu *cc; 397 struct callout_list *sc; 398 sbintime_t first, last, max, tmp_max; 399 uint32_t lookahead; 400 u_int firstb, lastb, nowb; 401 #ifdef CALLOUT_PROFILING 402 int depth_dir = 0, mpcalls_dir = 0, lockcalls_dir = 0; 403 #endif 404 405 cc = CC_SELF(); 406 mtx_lock_spin_flags(&cc->cc_lock, MTX_QUIET); 407 408 /* Compute the buckets of the last scan and present times. */ 409 firstb = callout_hash(cc->cc_lastscan); 410 cc->cc_lastscan = now; 411 nowb = callout_hash(now); 412 413 /* Compute the last bucket and minimum time of the bucket after it. */ 414 if (nowb == firstb) 415 lookahead = (SBT_1S / 16); 416 else if (nowb - firstb == 1) 417 lookahead = (SBT_1S / 8); 418 else 419 lookahead = (SBT_1S / 2); 420 first = last = now; 421 first += (lookahead / 2); 422 last += lookahead; 423 last &= (0xffffffffffffffffLLU << (32 - CC_HASH_SHIFT)); 424 lastb = callout_hash(last) - 1; 425 max = last; 426 427 /* 428 * Check if we wrapped around the entire wheel from the last scan. 429 * In case, we need to scan entirely the wheel for pending callouts. 430 */ 431 if (lastb - firstb >= callwheelsize) { 432 lastb = firstb + callwheelsize - 1; 433 if (nowb - firstb >= callwheelsize) 434 nowb = lastb; 435 } 436 437 /* Iterate callwheel from firstb to nowb and then up to lastb. */ 438 do { 439 sc = &cc->cc_callwheel[firstb & callwheelmask]; 440 tmp = LIST_FIRST(sc); 441 while (tmp != NULL) { 442 /* Run the callout if present time within allowed. */ 443 if (tmp->c_time <= now) { 444 /* 445 * Consumer told us the callout may be run 446 * directly from hardware interrupt context. 447 */ 448 if (tmp->c_iflags & CALLOUT_DIRECT) { 449 #ifdef CALLOUT_PROFILING 450 ++depth_dir; 451 #endif 452 cc_exec_next(cc) = 453 LIST_NEXT(tmp, c_links.le); 454 cc->cc_bucket = firstb & callwheelmask; 455 LIST_REMOVE(tmp, c_links.le); 456 softclock_call_cc(tmp, cc, 457 #ifdef CALLOUT_PROFILING 458 &mpcalls_dir, &lockcalls_dir, NULL, 459 #endif 460 1); 461 tmp = cc_exec_next(cc); 462 cc_exec_next(cc) = NULL; 463 } else { 464 tmpn = LIST_NEXT(tmp, c_links.le); 465 LIST_REMOVE(tmp, c_links.le); 466 TAILQ_INSERT_TAIL(&cc->cc_expireq, 467 tmp, c_links.tqe); 468 tmp->c_iflags |= CALLOUT_PROCESSED; 469 tmp = tmpn; 470 } 471 continue; 472 } 473 /* Skip events from distant future. */ 474 if (tmp->c_time >= max) 475 goto next; 476 /* 477 * Event minimal time is bigger than present maximal 478 * time, so it cannot be aggregated. 479 */ 480 if (tmp->c_time > last) { 481 lastb = nowb; 482 goto next; 483 } 484 /* Update first and last time, respecting this event. */ 485 if (tmp->c_time < first) 486 first = tmp->c_time; 487 tmp_max = tmp->c_time + tmp->c_precision; 488 if (tmp_max < last) 489 last = tmp_max; 490 next: 491 tmp = LIST_NEXT(tmp, c_links.le); 492 } 493 /* Proceed with the next bucket. */ 494 firstb++; 495 /* 496 * Stop if we looked after present time and found 497 * some event we can't execute at now. 498 * Stop if we looked far enough into the future. 499 */ 500 } while (((int)(firstb - lastb)) <= 0); 501 cc->cc_firstevent = last; 502 #ifndef NO_EVENTTIMERS 503 cpu_new_callout(curcpu, last, first); 504 #endif 505 #ifdef CALLOUT_PROFILING 506 avg_depth_dir += (depth_dir * 1000 - avg_depth_dir) >> 8; 507 avg_mpcalls_dir += (mpcalls_dir * 1000 - avg_mpcalls_dir) >> 8; 508 avg_lockcalls_dir += (lockcalls_dir * 1000 - avg_lockcalls_dir) >> 8; 509 #endif 510 mtx_unlock_spin_flags(&cc->cc_lock, MTX_QUIET); 511 /* 512 * swi_sched acquires the thread lock, so we don't want to call it 513 * with cc_lock held; incorrect locking order. 514 */ 515 if (!TAILQ_EMPTY(&cc->cc_expireq)) 516 swi_sched(cc->cc_cookie, 0); 517 } 518 519 static struct callout_cpu * 520 callout_lock(struct callout *c) 521 { 522 struct callout_cpu *cc; 523 int cpu; 524 525 for (;;) { 526 cpu = c->c_cpu; 527 #ifdef SMP 528 if (cpu == CPUBLOCK) { 529 while (c->c_cpu == CPUBLOCK) 530 cpu_spinwait(); 531 continue; 532 } 533 #endif 534 cc = CC_CPU(cpu); 535 CC_LOCK(cc); 536 if (cpu == c->c_cpu) 537 break; 538 CC_UNLOCK(cc); 539 } 540 return (cc); 541 } 542 543 static void 544 callout_cc_add(struct callout *c, struct callout_cpu *cc, 545 sbintime_t sbt, sbintime_t precision, void (*func)(void *), 546 void *arg, int cpu, int flags) 547 { 548 int bucket; 549 550 CC_LOCK_ASSERT(cc); 551 if (sbt < cc->cc_lastscan) 552 sbt = cc->cc_lastscan; 553 c->c_arg = arg; 554 c->c_iflags |= CALLOUT_PENDING; 555 c->c_iflags &= ~CALLOUT_PROCESSED; 556 c->c_flags |= CALLOUT_ACTIVE; 557 if (flags & C_DIRECT_EXEC) 558 c->c_iflags |= CALLOUT_DIRECT; 559 c->c_func = func; 560 c->c_time = sbt; 561 c->c_precision = precision; 562 bucket = callout_get_bucket(c->c_time); 563 CTR3(KTR_CALLOUT, "precision set for %p: %d.%08x", 564 c, (int)(c->c_precision >> 32), 565 (u_int)(c->c_precision & 0xffffffff)); 566 LIST_INSERT_HEAD(&cc->cc_callwheel[bucket], c, c_links.le); 567 if (cc->cc_bucket == bucket) 568 cc_exec_next(cc) = c; 569 #ifndef NO_EVENTTIMERS 570 /* 571 * Inform the eventtimers(4) subsystem there's a new callout 572 * that has been inserted, but only if really required. 573 */ 574 if (INT64_MAX - c->c_time < c->c_precision) 575 c->c_precision = INT64_MAX - c->c_time; 576 sbt = c->c_time + c->c_precision; 577 if (sbt < cc->cc_firstevent) { 578 cc->cc_firstevent = sbt; 579 cpu_new_callout(cpu, sbt, c->c_time); 580 } 581 #endif 582 } 583 584 static void 585 callout_cc_del(struct callout *c, struct callout_cpu *cc) 586 { 587 588 if ((c->c_iflags & CALLOUT_LOCAL_ALLOC) == 0) 589 return; 590 c->c_func = NULL; 591 SLIST_INSERT_HEAD(&cc->cc_callfree, c, c_links.sle); 592 } 593 594 static void 595 softclock_call_cc(struct callout *c, struct callout_cpu *cc, 596 #ifdef CALLOUT_PROFILING 597 int *mpcalls, int *lockcalls, int *gcalls, 598 #endif 599 int direct) 600 { 601 struct rm_priotracker tracker; 602 void (*c_func)(void *); 603 void *c_arg; 604 struct lock_class *class; 605 struct lock_object *c_lock; 606 uintptr_t lock_status; 607 int c_iflags; 608 #ifdef SMP 609 struct callout_cpu *new_cc; 610 void (*new_func)(void *); 611 void *new_arg; 612 int flags, new_cpu; 613 sbintime_t new_prec, new_time; 614 #endif 615 #if defined(DIAGNOSTIC) || defined(CALLOUT_PROFILING) 616 sbintime_t sbt1, sbt2; 617 struct timespec ts2; 618 static sbintime_t maxdt = 2 * SBT_1MS; /* 2 msec */ 619 static timeout_t *lastfunc; 620 #endif 621 622 KASSERT((c->c_iflags & CALLOUT_PENDING) == CALLOUT_PENDING, 623 ("softclock_call_cc: pend %p %x", c, c->c_iflags)); 624 KASSERT((c->c_flags & CALLOUT_ACTIVE) == CALLOUT_ACTIVE, 625 ("softclock_call_cc: act %p %x", c, c->c_flags)); 626 class = (c->c_lock != NULL) ? LOCK_CLASS(c->c_lock) : NULL; 627 lock_status = 0; 628 if (c->c_flags & CALLOUT_SHAREDLOCK) { 629 if (class == &lock_class_rm) 630 lock_status = (uintptr_t)&tracker; 631 else 632 lock_status = 1; 633 } 634 c_lock = c->c_lock; 635 c_func = c->c_func; 636 c_arg = c->c_arg; 637 c_iflags = c->c_iflags; 638 if (c->c_iflags & CALLOUT_LOCAL_ALLOC) 639 c->c_iflags = CALLOUT_LOCAL_ALLOC; 640 else 641 c->c_iflags &= ~CALLOUT_PENDING; 642 643 cc_exec_curr(cc, direct) = c; 644 cc_exec_cancel(cc, direct) = false; 645 CC_UNLOCK(cc); 646 if (c_lock != NULL) { 647 class->lc_lock(c_lock, lock_status); 648 /* 649 * The callout may have been cancelled 650 * while we switched locks. 651 */ 652 if (cc_exec_cancel(cc, direct)) { 653 class->lc_unlock(c_lock); 654 goto skip; 655 } 656 /* The callout cannot be stopped now. */ 657 cc_exec_cancel(cc, direct) = true; 658 if (c_lock == &Giant.lock_object) { 659 #ifdef CALLOUT_PROFILING 660 (*gcalls)++; 661 #endif 662 CTR3(KTR_CALLOUT, "callout giant %p func %p arg %p", 663 c, c_func, c_arg); 664 } else { 665 #ifdef CALLOUT_PROFILING 666 (*lockcalls)++; 667 #endif 668 CTR3(KTR_CALLOUT, "callout lock %p func %p arg %p", 669 c, c_func, c_arg); 670 } 671 } else { 672 #ifdef CALLOUT_PROFILING 673 (*mpcalls)++; 674 #endif 675 CTR3(KTR_CALLOUT, "callout %p func %p arg %p", 676 c, c_func, c_arg); 677 } 678 KTR_STATE3(KTR_SCHED, "callout", cc->cc_ktr_event_name, "running", 679 "func:%p", c_func, "arg:%p", c_arg, "direct:%d", direct); 680 #if defined(DIAGNOSTIC) || defined(CALLOUT_PROFILING) 681 sbt1 = sbinuptime(); 682 #endif 683 THREAD_NO_SLEEPING(); 684 SDT_PROBE1(callout_execute, kernel, , callout__start, c); 685 c_func(c_arg); 686 SDT_PROBE1(callout_execute, kernel, , callout__end, c); 687 THREAD_SLEEPING_OK(); 688 #if defined(DIAGNOSTIC) || defined(CALLOUT_PROFILING) 689 sbt2 = sbinuptime(); 690 sbt2 -= sbt1; 691 if (sbt2 > maxdt) { 692 if (lastfunc != c_func || sbt2 > maxdt * 2) { 693 ts2 = sbttots(sbt2); 694 printf( 695 "Expensive timeout(9) function: %p(%p) %jd.%09ld s\n", 696 c_func, c_arg, (intmax_t)ts2.tv_sec, ts2.tv_nsec); 697 } 698 maxdt = sbt2; 699 lastfunc = c_func; 700 } 701 #endif 702 KTR_STATE0(KTR_SCHED, "callout", cc->cc_ktr_event_name, "idle"); 703 CTR1(KTR_CALLOUT, "callout %p finished", c); 704 if ((c_iflags & CALLOUT_RETURNUNLOCKED) == 0) 705 class->lc_unlock(c_lock); 706 skip: 707 CC_LOCK(cc); 708 KASSERT(cc_exec_curr(cc, direct) == c, ("mishandled cc_curr")); 709 cc_exec_curr(cc, direct) = NULL; 710 if (cc_exec_waiting(cc, direct)) { 711 /* 712 * There is someone waiting for the 713 * callout to complete. 714 * If the callout was scheduled for 715 * migration just cancel it. 716 */ 717 if (cc_cce_migrating(cc, direct)) { 718 cc_cce_cleanup(cc, direct); 719 720 /* 721 * It should be assert here that the callout is not 722 * destroyed but that is not easy. 723 */ 724 c->c_iflags &= ~CALLOUT_DFRMIGRATION; 725 } 726 cc_exec_waiting(cc, direct) = false; 727 CC_UNLOCK(cc); 728 wakeup(&cc_exec_waiting(cc, direct)); 729 CC_LOCK(cc); 730 } else if (cc_cce_migrating(cc, direct)) { 731 KASSERT((c_iflags & CALLOUT_LOCAL_ALLOC) == 0, 732 ("Migrating legacy callout %p", c)); 733 #ifdef SMP 734 /* 735 * If the callout was scheduled for 736 * migration just perform it now. 737 */ 738 new_cpu = cc_migration_cpu(cc, direct); 739 new_time = cc_migration_time(cc, direct); 740 new_prec = cc_migration_prec(cc, direct); 741 new_func = cc_migration_func(cc, direct); 742 new_arg = cc_migration_arg(cc, direct); 743 cc_cce_cleanup(cc, direct); 744 745 /* 746 * It should be assert here that the callout is not destroyed 747 * but that is not easy. 748 * 749 * As first thing, handle deferred callout stops. 750 */ 751 if (!callout_migrating(c)) { 752 CTR3(KTR_CALLOUT, 753 "deferred cancelled %p func %p arg %p", 754 c, new_func, new_arg); 755 callout_cc_del(c, cc); 756 return; 757 } 758 c->c_iflags &= ~CALLOUT_DFRMIGRATION; 759 760 new_cc = callout_cpu_switch(c, cc, new_cpu); 761 flags = (direct) ? C_DIRECT_EXEC : 0; 762 callout_cc_add(c, new_cc, new_time, new_prec, new_func, 763 new_arg, new_cpu, flags); 764 CC_UNLOCK(new_cc); 765 CC_LOCK(cc); 766 #else 767 panic("migration should not happen"); 768 #endif 769 } 770 /* 771 * If the current callout is locally allocated (from 772 * timeout(9)) then put it on the freelist. 773 * 774 * Note: we need to check the cached copy of c_iflags because 775 * if it was not local, then it's not safe to deref the 776 * callout pointer. 777 */ 778 KASSERT((c_iflags & CALLOUT_LOCAL_ALLOC) == 0 || 779 c->c_iflags == CALLOUT_LOCAL_ALLOC, 780 ("corrupted callout")); 781 if (c_iflags & CALLOUT_LOCAL_ALLOC) 782 callout_cc_del(c, cc); 783 } 784 785 /* 786 * The callout mechanism is based on the work of Adam M. Costello and 787 * George Varghese, published in a technical report entitled "Redesigning 788 * the BSD Callout and Timer Facilities" and modified slightly for inclusion 789 * in FreeBSD by Justin T. Gibbs. The original work on the data structures 790 * used in this implementation was published by G. Varghese and T. Lauck in 791 * the paper "Hashed and Hierarchical Timing Wheels: Data Structures for 792 * the Efficient Implementation of a Timer Facility" in the Proceedings of 793 * the 11th ACM Annual Symposium on Operating Systems Principles, 794 * Austin, Texas Nov 1987. 795 */ 796 797 /* 798 * Software (low priority) clock interrupt. 799 * Run periodic events from timeout queue. 800 */ 801 void 802 softclock(void *arg) 803 { 804 struct callout_cpu *cc; 805 struct callout *c; 806 #ifdef CALLOUT_PROFILING 807 int depth = 0, gcalls = 0, lockcalls = 0, mpcalls = 0; 808 #endif 809 810 cc = (struct callout_cpu *)arg; 811 CC_LOCK(cc); 812 while ((c = TAILQ_FIRST(&cc->cc_expireq)) != NULL) { 813 TAILQ_REMOVE(&cc->cc_expireq, c, c_links.tqe); 814 softclock_call_cc(c, cc, 815 #ifdef CALLOUT_PROFILING 816 &mpcalls, &lockcalls, &gcalls, 817 #endif 818 0); 819 #ifdef CALLOUT_PROFILING 820 ++depth; 821 #endif 822 } 823 #ifdef CALLOUT_PROFILING 824 avg_depth += (depth * 1000 - avg_depth) >> 8; 825 avg_mpcalls += (mpcalls * 1000 - avg_mpcalls) >> 8; 826 avg_lockcalls += (lockcalls * 1000 - avg_lockcalls) >> 8; 827 avg_gcalls += (gcalls * 1000 - avg_gcalls) >> 8; 828 #endif 829 CC_UNLOCK(cc); 830 } 831 832 /* 833 * timeout -- 834 * Execute a function after a specified length of time. 835 * 836 * untimeout -- 837 * Cancel previous timeout function call. 838 * 839 * callout_handle_init -- 840 * Initialize a handle so that using it with untimeout is benign. 841 * 842 * See AT&T BCI Driver Reference Manual for specification. This 843 * implementation differs from that one in that although an 844 * identification value is returned from timeout, the original 845 * arguments to timeout as well as the identifier are used to 846 * identify entries for untimeout. 847 */ 848 struct callout_handle 849 timeout(ftn, arg, to_ticks) 850 timeout_t *ftn; 851 void *arg; 852 int to_ticks; 853 { 854 struct callout_cpu *cc; 855 struct callout *new; 856 struct callout_handle handle; 857 858 cc = CC_CPU(timeout_cpu); 859 CC_LOCK(cc); 860 /* Fill in the next free callout structure. */ 861 new = SLIST_FIRST(&cc->cc_callfree); 862 if (new == NULL) 863 /* XXX Attempt to malloc first */ 864 panic("timeout table full"); 865 SLIST_REMOVE_HEAD(&cc->cc_callfree, c_links.sle); 866 callout_reset(new, to_ticks, ftn, arg); 867 handle.callout = new; 868 CC_UNLOCK(cc); 869 870 return (handle); 871 } 872 873 void 874 untimeout(ftn, arg, handle) 875 timeout_t *ftn; 876 void *arg; 877 struct callout_handle handle; 878 { 879 struct callout_cpu *cc; 880 881 /* 882 * Check for a handle that was initialized 883 * by callout_handle_init, but never used 884 * for a real timeout. 885 */ 886 if (handle.callout == NULL) 887 return; 888 889 cc = callout_lock(handle.callout); 890 if (handle.callout->c_func == ftn && handle.callout->c_arg == arg) 891 callout_stop(handle.callout); 892 CC_UNLOCK(cc); 893 } 894 895 void 896 callout_handle_init(struct callout_handle *handle) 897 { 898 handle->callout = NULL; 899 } 900 901 /* 902 * New interface; clients allocate their own callout structures. 903 * 904 * callout_reset() - establish or change a timeout 905 * callout_stop() - disestablish a timeout 906 * callout_init() - initialize a callout structure so that it can 907 * safely be passed to callout_reset() and callout_stop() 908 * 909 * <sys/callout.h> defines three convenience macros: 910 * 911 * callout_active() - returns truth if callout has not been stopped, 912 * drained, or deactivated since the last time the callout was 913 * reset. 914 * callout_pending() - returns truth if callout is still waiting for timeout 915 * callout_deactivate() - marks the callout as having been serviced 916 */ 917 int 918 callout_reset_sbt_on(struct callout *c, sbintime_t sbt, sbintime_t precision, 919 void (*ftn)(void *), void *arg, int cpu, int flags) 920 { 921 sbintime_t to_sbt, pr; 922 struct callout_cpu *cc; 923 int cancelled, direct; 924 int ignore_cpu=0; 925 926 cancelled = 0; 927 if (cpu == -1) { 928 ignore_cpu = 1; 929 } else if ((cpu >= MAXCPU) || 930 ((CC_CPU(cpu))->cc_inited == 0)) { 931 /* Invalid CPU spec */ 932 panic("Invalid CPU in callout %d", cpu); 933 } 934 if (flags & C_ABSOLUTE) { 935 to_sbt = sbt; 936 } else { 937 if ((flags & C_HARDCLOCK) && (sbt < tick_sbt)) 938 sbt = tick_sbt; 939 if ((flags & C_HARDCLOCK) || 940 #ifdef NO_EVENTTIMERS 941 sbt >= sbt_timethreshold) { 942 to_sbt = getsbinuptime(); 943 944 /* Add safety belt for the case of hz > 1000. */ 945 to_sbt += tc_tick_sbt - tick_sbt; 946 #else 947 sbt >= sbt_tickthreshold) { 948 /* 949 * Obtain the time of the last hardclock() call on 950 * this CPU directly from the kern_clocksource.c. 951 * This value is per-CPU, but it is equal for all 952 * active ones. 953 */ 954 #ifdef __LP64__ 955 to_sbt = DPCPU_GET(hardclocktime); 956 #else 957 spinlock_enter(); 958 to_sbt = DPCPU_GET(hardclocktime); 959 spinlock_exit(); 960 #endif 961 #endif 962 if ((flags & C_HARDCLOCK) == 0) 963 to_sbt += tick_sbt; 964 } else 965 to_sbt = sbinuptime(); 966 if (INT64_MAX - to_sbt < sbt) 967 to_sbt = INT64_MAX; 968 else 969 to_sbt += sbt; 970 pr = ((C_PRELGET(flags) < 0) ? sbt >> tc_precexp : 971 sbt >> C_PRELGET(flags)); 972 if (pr > precision) 973 precision = pr; 974 } 975 /* 976 * This flag used to be added by callout_cc_add, but the 977 * first time you call this we could end up with the 978 * wrong direct flag if we don't do it before we add. 979 */ 980 if (flags & C_DIRECT_EXEC) { 981 direct = 1; 982 } else { 983 direct = 0; 984 } 985 KASSERT(!direct || c->c_lock == NULL, 986 ("%s: direct callout %p has lock", __func__, c)); 987 cc = callout_lock(c); 988 /* 989 * Don't allow migration of pre-allocated callouts lest they 990 * become unbalanced or handle the case where the user does 991 * not care. 992 */ 993 if ((c->c_iflags & CALLOUT_LOCAL_ALLOC) || 994 ignore_cpu) { 995 cpu = c->c_cpu; 996 } 997 998 if (cc_exec_curr(cc, direct) == c) { 999 /* 1000 * We're being asked to reschedule a callout which is 1001 * currently in progress. If there is a lock then we 1002 * can cancel the callout if it has not really started. 1003 */ 1004 if (c->c_lock != NULL && !cc_exec_cancel(cc, direct)) 1005 cancelled = cc_exec_cancel(cc, direct) = true; 1006 if (cc_exec_waiting(cc, direct)) { 1007 /* 1008 * Someone has called callout_drain to kill this 1009 * callout. Don't reschedule. 1010 */ 1011 CTR4(KTR_CALLOUT, "%s %p func %p arg %p", 1012 cancelled ? "cancelled" : "failed to cancel", 1013 c, c->c_func, c->c_arg); 1014 CC_UNLOCK(cc); 1015 return (cancelled); 1016 } 1017 #ifdef SMP 1018 if (callout_migrating(c)) { 1019 /* 1020 * This only occurs when a second callout_reset_sbt_on 1021 * is made after a previous one moved it into 1022 * deferred migration (below). Note we do *not* change 1023 * the prev_cpu even though the previous target may 1024 * be different. 1025 */ 1026 cc_migration_cpu(cc, direct) = cpu; 1027 cc_migration_time(cc, direct) = to_sbt; 1028 cc_migration_prec(cc, direct) = precision; 1029 cc_migration_func(cc, direct) = ftn; 1030 cc_migration_arg(cc, direct) = arg; 1031 cancelled = 1; 1032 CC_UNLOCK(cc); 1033 return (cancelled); 1034 } 1035 #endif 1036 } 1037 if (c->c_iflags & CALLOUT_PENDING) { 1038 if ((c->c_iflags & CALLOUT_PROCESSED) == 0) { 1039 if (cc_exec_next(cc) == c) 1040 cc_exec_next(cc) = LIST_NEXT(c, c_links.le); 1041 LIST_REMOVE(c, c_links.le); 1042 } else { 1043 TAILQ_REMOVE(&cc->cc_expireq, c, c_links.tqe); 1044 } 1045 cancelled = 1; 1046 c->c_iflags &= ~ CALLOUT_PENDING; 1047 c->c_flags &= ~ CALLOUT_ACTIVE; 1048 } 1049 1050 #ifdef SMP 1051 /* 1052 * If the callout must migrate try to perform it immediately. 1053 * If the callout is currently running, just defer the migration 1054 * to a more appropriate moment. 1055 */ 1056 if (c->c_cpu != cpu) { 1057 if (cc_exec_curr(cc, direct) == c) { 1058 /* 1059 * Pending will have been removed since we are 1060 * actually executing the callout on another 1061 * CPU. That callout should be waiting on the 1062 * lock the caller holds. If we set both 1063 * active/and/pending after we return and the 1064 * lock on the executing callout proceeds, it 1065 * will then see pending is true and return. 1066 * At the return from the actual callout execution 1067 * the migration will occur in softclock_call_cc 1068 * and this new callout will be placed on the 1069 * new CPU via a call to callout_cpu_switch() which 1070 * will get the lock on the right CPU followed 1071 * by a call callout_cc_add() which will add it there. 1072 * (see above in softclock_call_cc()). 1073 */ 1074 cc_migration_cpu(cc, direct) = cpu; 1075 cc_migration_time(cc, direct) = to_sbt; 1076 cc_migration_prec(cc, direct) = precision; 1077 cc_migration_func(cc, direct) = ftn; 1078 cc_migration_arg(cc, direct) = arg; 1079 c->c_iflags |= (CALLOUT_DFRMIGRATION | CALLOUT_PENDING); 1080 c->c_flags |= CALLOUT_ACTIVE; 1081 CTR6(KTR_CALLOUT, 1082 "migration of %p func %p arg %p in %d.%08x to %u deferred", 1083 c, c->c_func, c->c_arg, (int)(to_sbt >> 32), 1084 (u_int)(to_sbt & 0xffffffff), cpu); 1085 CC_UNLOCK(cc); 1086 return (cancelled); 1087 } 1088 cc = callout_cpu_switch(c, cc, cpu); 1089 } 1090 #endif 1091 1092 callout_cc_add(c, cc, to_sbt, precision, ftn, arg, cpu, flags); 1093 CTR6(KTR_CALLOUT, "%sscheduled %p func %p arg %p in %d.%08x", 1094 cancelled ? "re" : "", c, c->c_func, c->c_arg, (int)(to_sbt >> 32), 1095 (u_int)(to_sbt & 0xffffffff)); 1096 CC_UNLOCK(cc); 1097 1098 return (cancelled); 1099 } 1100 1101 /* 1102 * Common idioms that can be optimized in the future. 1103 */ 1104 int 1105 callout_schedule_on(struct callout *c, int to_ticks, int cpu) 1106 { 1107 return callout_reset_on(c, to_ticks, c->c_func, c->c_arg, cpu); 1108 } 1109 1110 int 1111 callout_schedule(struct callout *c, int to_ticks) 1112 { 1113 return callout_reset_on(c, to_ticks, c->c_func, c->c_arg, c->c_cpu); 1114 } 1115 1116 int 1117 _callout_stop_safe(c, flags) 1118 struct callout *c; 1119 int flags; 1120 { 1121 struct callout_cpu *cc, *old_cc; 1122 struct lock_class *class; 1123 int direct, sq_locked, use_lock; 1124 int not_on_a_list; 1125 1126 /* 1127 * Some old subsystems don't hold Giant while running a callout_stop(), 1128 * so just discard this check for the moment. 1129 */ 1130 if ((flags & CS_DRAIN) == 0 && c->c_lock != NULL) { 1131 if (c->c_lock == &Giant.lock_object) 1132 use_lock = mtx_owned(&Giant); 1133 else { 1134 use_lock = 1; 1135 class = LOCK_CLASS(c->c_lock); 1136 class->lc_assert(c->c_lock, LA_XLOCKED); 1137 } 1138 } else 1139 use_lock = 0; 1140 if (c->c_iflags & CALLOUT_DIRECT) { 1141 direct = 1; 1142 } else { 1143 direct = 0; 1144 } 1145 sq_locked = 0; 1146 old_cc = NULL; 1147 again: 1148 cc = callout_lock(c); 1149 1150 if ((c->c_iflags & (CALLOUT_DFRMIGRATION | CALLOUT_PENDING)) == 1151 (CALLOUT_DFRMIGRATION | CALLOUT_PENDING) && 1152 ((c->c_flags & CALLOUT_ACTIVE) == CALLOUT_ACTIVE)) { 1153 /* 1154 * Special case where this slipped in while we 1155 * were migrating *as* the callout is about to 1156 * execute. The caller probably holds the lock 1157 * the callout wants. 1158 * 1159 * Get rid of the migration first. Then set 1160 * the flag that tells this code *not* to 1161 * try to remove it from any lists (its not 1162 * on one yet). When the callout wheel runs, 1163 * it will ignore this callout. 1164 */ 1165 c->c_iflags &= ~CALLOUT_PENDING; 1166 c->c_flags &= ~CALLOUT_ACTIVE; 1167 not_on_a_list = 1; 1168 } else { 1169 not_on_a_list = 0; 1170 } 1171 1172 /* 1173 * If the callout was migrating while the callout cpu lock was 1174 * dropped, just drop the sleepqueue lock and check the states 1175 * again. 1176 */ 1177 if (sq_locked != 0 && cc != old_cc) { 1178 #ifdef SMP 1179 CC_UNLOCK(cc); 1180 sleepq_release(&cc_exec_waiting(old_cc, direct)); 1181 sq_locked = 0; 1182 old_cc = NULL; 1183 goto again; 1184 #else 1185 panic("migration should not happen"); 1186 #endif 1187 } 1188 1189 /* 1190 * If the callout isn't pending, it's not on the queue, so 1191 * don't attempt to remove it from the queue. We can try to 1192 * stop it by other means however. 1193 */ 1194 if (!(c->c_iflags & CALLOUT_PENDING)) { 1195 c->c_flags &= ~CALLOUT_ACTIVE; 1196 1197 /* 1198 * If it wasn't on the queue and it isn't the current 1199 * callout, then we can't stop it, so just bail. 1200 */ 1201 if (cc_exec_curr(cc, direct) != c) { 1202 CTR3(KTR_CALLOUT, "failed to stop %p func %p arg %p", 1203 c, c->c_func, c->c_arg); 1204 CC_UNLOCK(cc); 1205 if (sq_locked) 1206 sleepq_release(&cc_exec_waiting(cc, direct)); 1207 return (0); 1208 } 1209 1210 if ((flags & CS_DRAIN) != 0) { 1211 /* 1212 * The current callout is running (or just 1213 * about to run) and blocking is allowed, so 1214 * just wait for the current invocation to 1215 * finish. 1216 */ 1217 while (cc_exec_curr(cc, direct) == c) { 1218 /* 1219 * Use direct calls to sleepqueue interface 1220 * instead of cv/msleep in order to avoid 1221 * a LOR between cc_lock and sleepqueue 1222 * chain spinlocks. This piece of code 1223 * emulates a msleep_spin() call actually. 1224 * 1225 * If we already have the sleepqueue chain 1226 * locked, then we can safely block. If we 1227 * don't already have it locked, however, 1228 * we have to drop the cc_lock to lock 1229 * it. This opens several races, so we 1230 * restart at the beginning once we have 1231 * both locks. If nothing has changed, then 1232 * we will end up back here with sq_locked 1233 * set. 1234 */ 1235 if (!sq_locked) { 1236 CC_UNLOCK(cc); 1237 sleepq_lock( 1238 &cc_exec_waiting(cc, direct)); 1239 sq_locked = 1; 1240 old_cc = cc; 1241 goto again; 1242 } 1243 1244 /* 1245 * Migration could be cancelled here, but 1246 * as long as it is still not sure when it 1247 * will be packed up, just let softclock() 1248 * take care of it. 1249 */ 1250 cc_exec_waiting(cc, direct) = true; 1251 DROP_GIANT(); 1252 CC_UNLOCK(cc); 1253 sleepq_add( 1254 &cc_exec_waiting(cc, direct), 1255 &cc->cc_lock.lock_object, "codrain", 1256 SLEEPQ_SLEEP, 0); 1257 sleepq_wait( 1258 &cc_exec_waiting(cc, direct), 1259 0); 1260 sq_locked = 0; 1261 old_cc = NULL; 1262 1263 /* Reacquire locks previously released. */ 1264 PICKUP_GIANT(); 1265 CC_LOCK(cc); 1266 } 1267 } else if (use_lock && 1268 !cc_exec_cancel(cc, direct)) { 1269 1270 /* 1271 * The current callout is waiting for its 1272 * lock which we hold. Cancel the callout 1273 * and return. After our caller drops the 1274 * lock, the callout will be skipped in 1275 * softclock(). 1276 */ 1277 cc_exec_cancel(cc, direct) = true; 1278 CTR3(KTR_CALLOUT, "cancelled %p func %p arg %p", 1279 c, c->c_func, c->c_arg); 1280 KASSERT(!cc_cce_migrating(cc, direct), 1281 ("callout wrongly scheduled for migration")); 1282 if (callout_migrating(c)) { 1283 c->c_iflags &= ~CALLOUT_DFRMIGRATION; 1284 #ifdef SMP 1285 cc_migration_cpu(cc, direct) = CPUBLOCK; 1286 cc_migration_time(cc, direct) = 0; 1287 cc_migration_prec(cc, direct) = 0; 1288 cc_migration_func(cc, direct) = NULL; 1289 cc_migration_arg(cc, direct) = NULL; 1290 #endif 1291 } 1292 CC_UNLOCK(cc); 1293 KASSERT(!sq_locked, ("sleepqueue chain locked")); 1294 return (1); 1295 } else if (callout_migrating(c)) { 1296 /* 1297 * The callout is currently being serviced 1298 * and the "next" callout is scheduled at 1299 * its completion with a migration. We remove 1300 * the migration flag so it *won't* get rescheduled, 1301 * but we can't stop the one thats running so 1302 * we return 0. 1303 */ 1304 c->c_iflags &= ~CALLOUT_DFRMIGRATION; 1305 #ifdef SMP 1306 /* 1307 * We can't call cc_cce_cleanup here since 1308 * if we do it will remove .ce_curr and 1309 * its still running. This will prevent a 1310 * reschedule of the callout when the 1311 * execution completes. 1312 */ 1313 cc_migration_cpu(cc, direct) = CPUBLOCK; 1314 cc_migration_time(cc, direct) = 0; 1315 cc_migration_prec(cc, direct) = 0; 1316 cc_migration_func(cc, direct) = NULL; 1317 cc_migration_arg(cc, direct) = NULL; 1318 #endif 1319 CTR3(KTR_CALLOUT, "postponing stop %p func %p arg %p", 1320 c, c->c_func, c->c_arg); 1321 CC_UNLOCK(cc); 1322 return ((flags & CS_MIGRBLOCK) != 0); 1323 } 1324 CTR3(KTR_CALLOUT, "failed to stop %p func %p arg %p", 1325 c, c->c_func, c->c_arg); 1326 CC_UNLOCK(cc); 1327 KASSERT(!sq_locked, ("sleepqueue chain still locked")); 1328 return (0); 1329 } 1330 if (sq_locked) 1331 sleepq_release(&cc_exec_waiting(cc, direct)); 1332 1333 c->c_iflags &= ~CALLOUT_PENDING; 1334 c->c_flags &= ~CALLOUT_ACTIVE; 1335 1336 CTR3(KTR_CALLOUT, "cancelled %p func %p arg %p", 1337 c, c->c_func, c->c_arg); 1338 if (not_on_a_list == 0) { 1339 if ((c->c_iflags & CALLOUT_PROCESSED) == 0) { 1340 if (cc_exec_next(cc) == c) 1341 cc_exec_next(cc) = LIST_NEXT(c, c_links.le); 1342 LIST_REMOVE(c, c_links.le); 1343 } else { 1344 TAILQ_REMOVE(&cc->cc_expireq, c, c_links.tqe); 1345 } 1346 } 1347 callout_cc_del(c, cc); 1348 CC_UNLOCK(cc); 1349 return (1); 1350 } 1351 1352 void 1353 callout_init(c, mpsafe) 1354 struct callout *c; 1355 int mpsafe; 1356 { 1357 bzero(c, sizeof *c); 1358 if (mpsafe) { 1359 c->c_lock = NULL; 1360 c->c_iflags = CALLOUT_RETURNUNLOCKED; 1361 } else { 1362 c->c_lock = &Giant.lock_object; 1363 c->c_iflags = 0; 1364 } 1365 c->c_cpu = timeout_cpu; 1366 } 1367 1368 void 1369 _callout_init_lock(c, lock, flags) 1370 struct callout *c; 1371 struct lock_object *lock; 1372 int flags; 1373 { 1374 bzero(c, sizeof *c); 1375 c->c_lock = lock; 1376 KASSERT((flags & ~(CALLOUT_RETURNUNLOCKED | CALLOUT_SHAREDLOCK)) == 0, 1377 ("callout_init_lock: bad flags %d", flags)); 1378 KASSERT(lock != NULL || (flags & CALLOUT_RETURNUNLOCKED) == 0, 1379 ("callout_init_lock: CALLOUT_RETURNUNLOCKED with no lock")); 1380 KASSERT(lock == NULL || !(LOCK_CLASS(lock)->lc_flags & 1381 (LC_SPINLOCK | LC_SLEEPABLE)), ("%s: invalid lock class", 1382 __func__)); 1383 c->c_iflags = flags & (CALLOUT_RETURNUNLOCKED | CALLOUT_SHAREDLOCK); 1384 c->c_cpu = timeout_cpu; 1385 } 1386 1387 #ifdef APM_FIXUP_CALLTODO 1388 /* 1389 * Adjust the kernel calltodo timeout list. This routine is used after 1390 * an APM resume to recalculate the calltodo timer list values with the 1391 * number of hz's we have been sleeping. The next hardclock() will detect 1392 * that there are fired timers and run softclock() to execute them. 1393 * 1394 * Please note, I have not done an exhaustive analysis of what code this 1395 * might break. I am motivated to have my select()'s and alarm()'s that 1396 * have expired during suspend firing upon resume so that the applications 1397 * which set the timer can do the maintanence the timer was for as close 1398 * as possible to the originally intended time. Testing this code for a 1399 * week showed that resuming from a suspend resulted in 22 to 25 timers 1400 * firing, which seemed independant on whether the suspend was 2 hours or 1401 * 2 days. Your milage may vary. - Ken Key <key@cs.utk.edu> 1402 */ 1403 void 1404 adjust_timeout_calltodo(time_change) 1405 struct timeval *time_change; 1406 { 1407 register struct callout *p; 1408 unsigned long delta_ticks; 1409 1410 /* 1411 * How many ticks were we asleep? 1412 * (stolen from tvtohz()). 1413 */ 1414 1415 /* Don't do anything */ 1416 if (time_change->tv_sec < 0) 1417 return; 1418 else if (time_change->tv_sec <= LONG_MAX / 1000000) 1419 delta_ticks = (time_change->tv_sec * 1000000 + 1420 time_change->tv_usec + (tick - 1)) / tick + 1; 1421 else if (time_change->tv_sec <= LONG_MAX / hz) 1422 delta_ticks = time_change->tv_sec * hz + 1423 (time_change->tv_usec + (tick - 1)) / tick + 1; 1424 else 1425 delta_ticks = LONG_MAX; 1426 1427 if (delta_ticks > INT_MAX) 1428 delta_ticks = INT_MAX; 1429 1430 /* 1431 * Now rip through the timer calltodo list looking for timers 1432 * to expire. 1433 */ 1434 1435 /* don't collide with softclock() */ 1436 CC_LOCK(cc); 1437 for (p = calltodo.c_next; p != NULL; p = p->c_next) { 1438 p->c_time -= delta_ticks; 1439 1440 /* Break if the timer had more time on it than delta_ticks */ 1441 if (p->c_time > 0) 1442 break; 1443 1444 /* take back the ticks the timer didn't use (p->c_time <= 0) */ 1445 delta_ticks = -p->c_time; 1446 } 1447 CC_UNLOCK(cc); 1448 1449 return; 1450 } 1451 #endif /* APM_FIXUP_CALLTODO */ 1452 1453 static int 1454 flssbt(sbintime_t sbt) 1455 { 1456 1457 sbt += (uint64_t)sbt >> 1; 1458 if (sizeof(long) >= sizeof(sbintime_t)) 1459 return (flsl(sbt)); 1460 if (sbt >= SBT_1S) 1461 return (flsl(((uint64_t)sbt) >> 32) + 32); 1462 return (flsl(sbt)); 1463 } 1464 1465 /* 1466 * Dump immediate statistic snapshot of the scheduled callouts. 1467 */ 1468 static int 1469 sysctl_kern_callout_stat(SYSCTL_HANDLER_ARGS) 1470 { 1471 struct callout *tmp; 1472 struct callout_cpu *cc; 1473 struct callout_list *sc; 1474 sbintime_t maxpr, maxt, medpr, medt, now, spr, st, t; 1475 int ct[64], cpr[64], ccpbk[32]; 1476 int error, val, i, count, tcum, pcum, maxc, c, medc; 1477 #ifdef SMP 1478 int cpu; 1479 #endif 1480 1481 val = 0; 1482 error = sysctl_handle_int(oidp, &val, 0, req); 1483 if (error != 0 || req->newptr == NULL) 1484 return (error); 1485 count = maxc = 0; 1486 st = spr = maxt = maxpr = 0; 1487 bzero(ccpbk, sizeof(ccpbk)); 1488 bzero(ct, sizeof(ct)); 1489 bzero(cpr, sizeof(cpr)); 1490 now = sbinuptime(); 1491 #ifdef SMP 1492 CPU_FOREACH(cpu) { 1493 cc = CC_CPU(cpu); 1494 #else 1495 cc = CC_CPU(timeout_cpu); 1496 #endif 1497 CC_LOCK(cc); 1498 for (i = 0; i < callwheelsize; i++) { 1499 sc = &cc->cc_callwheel[i]; 1500 c = 0; 1501 LIST_FOREACH(tmp, sc, c_links.le) { 1502 c++; 1503 t = tmp->c_time - now; 1504 if (t < 0) 1505 t = 0; 1506 st += t / SBT_1US; 1507 spr += tmp->c_precision / SBT_1US; 1508 if (t > maxt) 1509 maxt = t; 1510 if (tmp->c_precision > maxpr) 1511 maxpr = tmp->c_precision; 1512 ct[flssbt(t)]++; 1513 cpr[flssbt(tmp->c_precision)]++; 1514 } 1515 if (c > maxc) 1516 maxc = c; 1517 ccpbk[fls(c + c / 2)]++; 1518 count += c; 1519 } 1520 CC_UNLOCK(cc); 1521 #ifdef SMP 1522 } 1523 #endif 1524 1525 for (i = 0, tcum = 0; i < 64 && tcum < count / 2; i++) 1526 tcum += ct[i]; 1527 medt = (i >= 2) ? (((sbintime_t)1) << (i - 2)) : 0; 1528 for (i = 0, pcum = 0; i < 64 && pcum < count / 2; i++) 1529 pcum += cpr[i]; 1530 medpr = (i >= 2) ? (((sbintime_t)1) << (i - 2)) : 0; 1531 for (i = 0, c = 0; i < 32 && c < count / 2; i++) 1532 c += ccpbk[i]; 1533 medc = (i >= 2) ? (1 << (i - 2)) : 0; 1534 1535 printf("Scheduled callouts statistic snapshot:\n"); 1536 printf(" Callouts: %6d Buckets: %6d*%-3d Bucket size: 0.%06ds\n", 1537 count, callwheelsize, mp_ncpus, 1000000 >> CC_HASH_SHIFT); 1538 printf(" C/Bk: med %5d avg %6d.%06jd max %6d\n", 1539 medc, 1540 count / callwheelsize / mp_ncpus, 1541 (uint64_t)count * 1000000 / callwheelsize / mp_ncpus % 1000000, 1542 maxc); 1543 printf(" Time: med %5jd.%06jds avg %6jd.%06jds max %6jd.%06jds\n", 1544 medt / SBT_1S, (medt & 0xffffffff) * 1000000 >> 32, 1545 (st / count) / 1000000, (st / count) % 1000000, 1546 maxt / SBT_1S, (maxt & 0xffffffff) * 1000000 >> 32); 1547 printf(" Prec: med %5jd.%06jds avg %6jd.%06jds max %6jd.%06jds\n", 1548 medpr / SBT_1S, (medpr & 0xffffffff) * 1000000 >> 32, 1549 (spr / count) / 1000000, (spr / count) % 1000000, 1550 maxpr / SBT_1S, (maxpr & 0xffffffff) * 1000000 >> 32); 1551 printf(" Distribution: \tbuckets\t time\t tcum\t" 1552 " prec\t pcum\n"); 1553 for (i = 0, tcum = pcum = 0; i < 64; i++) { 1554 if (ct[i] == 0 && cpr[i] == 0) 1555 continue; 1556 t = (i != 0) ? (((sbintime_t)1) << (i - 1)) : 0; 1557 tcum += ct[i]; 1558 pcum += cpr[i]; 1559 printf(" %10jd.%06jds\t 2**%d\t%7d\t%7d\t%7d\t%7d\n", 1560 t / SBT_1S, (t & 0xffffffff) * 1000000 >> 32, 1561 i - 1 - (32 - CC_HASH_SHIFT), 1562 ct[i], tcum, cpr[i], pcum); 1563 } 1564 return (error); 1565 } 1566 SYSCTL_PROC(_kern, OID_AUTO, callout_stat, 1567 CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_MPSAFE, 1568 0, 0, sysctl_kern_callout_stat, "I", 1569 "Dump immediate statistic snapshot of the scheduled callouts");
Cache object: 7f6ab6ab5f6917c177c90300841bbd92
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