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/11.2/sys/kern/kern_timeout.c 331722 2018-03-29 02:50:57Z eadler $"); 39 40 #include "opt_callout_profiling.h" 41 #include "opt_ddb.h" 42 #if defined(__arm__) 43 #include "opt_timer.h" 44 #endif 45 #include "opt_rss.h" 46 47 #include <sys/param.h> 48 #include <sys/systm.h> 49 #include <sys/bus.h> 50 #include <sys/callout.h> 51 #include <sys/file.h> 52 #include <sys/interrupt.h> 53 #include <sys/kernel.h> 54 #include <sys/ktr.h> 55 #include <sys/lock.h> 56 #include <sys/malloc.h> 57 #include <sys/mutex.h> 58 #include <sys/proc.h> 59 #include <sys/sdt.h> 60 #include <sys/sleepqueue.h> 61 #include <sys/sysctl.h> 62 #include <sys/smp.h> 63 64 #ifdef DDB 65 #include <ddb/ddb.h> 66 #include <machine/_inttypes.h> 67 #endif 68 69 #ifdef SMP 70 #include <machine/cpu.h> 71 #endif 72 73 #ifndef NO_EVENTTIMERS 74 DPCPU_DECLARE(sbintime_t, hardclocktime); 75 #endif 76 77 SDT_PROVIDER_DEFINE(callout_execute); 78 SDT_PROBE_DEFINE1(callout_execute, , , callout__start, "struct callout *"); 79 SDT_PROBE_DEFINE1(callout_execute, , , callout__end, "struct callout *"); 80 81 #ifdef CALLOUT_PROFILING 82 static int avg_depth; 83 SYSCTL_INT(_debug, OID_AUTO, to_avg_depth, CTLFLAG_RD, &avg_depth, 0, 84 "Average number of items examined per softclock call. Units = 1/1000"); 85 static int avg_gcalls; 86 SYSCTL_INT(_debug, OID_AUTO, to_avg_gcalls, CTLFLAG_RD, &avg_gcalls, 0, 87 "Average number of Giant callouts made per softclock call. Units = 1/1000"); 88 static int avg_lockcalls; 89 SYSCTL_INT(_debug, OID_AUTO, to_avg_lockcalls, CTLFLAG_RD, &avg_lockcalls, 0, 90 "Average number of lock callouts made per softclock call. Units = 1/1000"); 91 static int avg_mpcalls; 92 SYSCTL_INT(_debug, OID_AUTO, to_avg_mpcalls, CTLFLAG_RD, &avg_mpcalls, 0, 93 "Average number of MP callouts made per softclock call. Units = 1/1000"); 94 static int avg_depth_dir; 95 SYSCTL_INT(_debug, OID_AUTO, to_avg_depth_dir, CTLFLAG_RD, &avg_depth_dir, 0, 96 "Average number of direct callouts examined per callout_process call. " 97 "Units = 1/1000"); 98 static int avg_lockcalls_dir; 99 SYSCTL_INT(_debug, OID_AUTO, to_avg_lockcalls_dir, CTLFLAG_RD, 100 &avg_lockcalls_dir, 0, "Average number of lock direct callouts made per " 101 "callout_process call. Units = 1/1000"); 102 static int avg_mpcalls_dir; 103 SYSCTL_INT(_debug, OID_AUTO, to_avg_mpcalls_dir, CTLFLAG_RD, &avg_mpcalls_dir, 104 0, "Average number of MP direct callouts made per callout_process call. " 105 "Units = 1/1000"); 106 #endif 107 108 static int ncallout; 109 SYSCTL_INT(_kern, OID_AUTO, ncallout, CTLFLAG_RDTUN | CTLFLAG_NOFETCH, &ncallout, 0, 110 "Number of entries in callwheel and size of timeout() preallocation"); 111 112 #ifdef RSS 113 static int pin_default_swi = 1; 114 static int pin_pcpu_swi = 1; 115 #else 116 static int pin_default_swi = 0; 117 static int pin_pcpu_swi = 0; 118 #endif 119 120 SYSCTL_INT(_kern, OID_AUTO, pin_default_swi, CTLFLAG_RDTUN | CTLFLAG_NOFETCH, &pin_default_swi, 121 0, "Pin the default (non-per-cpu) swi (shared with PCPU 0 swi)"); 122 SYSCTL_INT(_kern, OID_AUTO, pin_pcpu_swi, CTLFLAG_RDTUN | CTLFLAG_NOFETCH, &pin_pcpu_swi, 123 0, "Pin the per-CPU swis (except PCPU 0, which is also default"); 124 125 /* 126 * TODO: 127 * allocate more timeout table slots when table overflows. 128 */ 129 u_int callwheelsize, callwheelmask; 130 131 /* 132 * The callout cpu exec entities represent informations necessary for 133 * describing the state of callouts currently running on the CPU and the ones 134 * necessary for migrating callouts to the new callout cpu. In particular, 135 * the first entry of the array cc_exec_entity holds informations for callout 136 * running in SWI thread context, while the second one holds informations 137 * for callout running directly from hardware interrupt context. 138 * The cached informations are very important for deferring migration when 139 * the migrating callout is already running. 140 */ 141 struct cc_exec { 142 struct callout *cc_curr; 143 void (*cc_drain)(void *); 144 #ifdef SMP 145 void (*ce_migration_func)(void *); 146 void *ce_migration_arg; 147 int ce_migration_cpu; 148 sbintime_t ce_migration_time; 149 sbintime_t ce_migration_prec; 150 #endif 151 bool cc_cancel; 152 bool cc_waiting; 153 }; 154 155 /* 156 * There is one struct callout_cpu per cpu, holding all relevant 157 * state for the callout processing thread on the individual CPU. 158 */ 159 struct callout_cpu { 160 struct mtx_padalign cc_lock; 161 struct cc_exec cc_exec_entity[2]; 162 struct callout *cc_next; 163 struct callout *cc_callout; 164 struct callout_list *cc_callwheel; 165 struct callout_tailq cc_expireq; 166 struct callout_slist cc_callfree; 167 sbintime_t cc_firstevent; 168 sbintime_t cc_lastscan; 169 void *cc_cookie; 170 u_int cc_bucket; 171 u_int cc_inited; 172 char cc_ktr_event_name[20]; 173 }; 174 175 #define callout_migrating(c) ((c)->c_iflags & CALLOUT_DFRMIGRATION) 176 177 #define cc_exec_curr(cc, dir) cc->cc_exec_entity[dir].cc_curr 178 #define cc_exec_drain(cc, dir) cc->cc_exec_entity[dir].cc_drain 179 #define cc_exec_next(cc) cc->cc_next 180 #define cc_exec_cancel(cc, dir) cc->cc_exec_entity[dir].cc_cancel 181 #define cc_exec_waiting(cc, dir) cc->cc_exec_entity[dir].cc_waiting 182 #ifdef SMP 183 #define cc_migration_func(cc, dir) cc->cc_exec_entity[dir].ce_migration_func 184 #define cc_migration_arg(cc, dir) cc->cc_exec_entity[dir].ce_migration_arg 185 #define cc_migration_cpu(cc, dir) cc->cc_exec_entity[dir].ce_migration_cpu 186 #define cc_migration_time(cc, dir) cc->cc_exec_entity[dir].ce_migration_time 187 #define cc_migration_prec(cc, dir) cc->cc_exec_entity[dir].ce_migration_prec 188 189 struct callout_cpu cc_cpu[MAXCPU]; 190 #define CPUBLOCK MAXCPU 191 #define CC_CPU(cpu) (&cc_cpu[(cpu)]) 192 #define CC_SELF() CC_CPU(PCPU_GET(cpuid)) 193 #else 194 struct callout_cpu cc_cpu; 195 #define CC_CPU(cpu) &cc_cpu 196 #define CC_SELF() &cc_cpu 197 #endif 198 #define CC_LOCK(cc) mtx_lock_spin(&(cc)->cc_lock) 199 #define CC_UNLOCK(cc) mtx_unlock_spin(&(cc)->cc_lock) 200 #define CC_LOCK_ASSERT(cc) mtx_assert(&(cc)->cc_lock, MA_OWNED) 201 202 static int timeout_cpu; 203 204 static void callout_cpu_init(struct callout_cpu *cc, int cpu); 205 static void softclock_call_cc(struct callout *c, struct callout_cpu *cc, 206 #ifdef CALLOUT_PROFILING 207 int *mpcalls, int *lockcalls, int *gcalls, 208 #endif 209 int direct); 210 211 static MALLOC_DEFINE(M_CALLOUT, "callout", "Callout datastructures"); 212 213 /** 214 * Locked by cc_lock: 215 * cc_curr - If a callout is in progress, it is cc_curr. 216 * If cc_curr is non-NULL, threads waiting in 217 * callout_drain() will be woken up as soon as the 218 * relevant callout completes. 219 * cc_cancel - Changing to 1 with both callout_lock and cc_lock held 220 * guarantees that the current callout will not run. 221 * The softclock() function sets this to 0 before it 222 * drops callout_lock to acquire c_lock, and it calls 223 * the handler only if curr_cancelled is still 0 after 224 * cc_lock is successfully acquired. 225 * cc_waiting - If a thread is waiting in callout_drain(), then 226 * callout_wait is nonzero. Set only when 227 * cc_curr is non-NULL. 228 */ 229 230 /* 231 * Resets the execution entity tied to a specific callout cpu. 232 */ 233 static void 234 cc_cce_cleanup(struct callout_cpu *cc, int direct) 235 { 236 237 cc_exec_curr(cc, direct) = NULL; 238 cc_exec_cancel(cc, direct) = false; 239 cc_exec_waiting(cc, direct) = false; 240 #ifdef SMP 241 cc_migration_cpu(cc, direct) = CPUBLOCK; 242 cc_migration_time(cc, direct) = 0; 243 cc_migration_prec(cc, direct) = 0; 244 cc_migration_func(cc, direct) = NULL; 245 cc_migration_arg(cc, direct) = NULL; 246 #endif 247 } 248 249 /* 250 * Checks if migration is requested by a specific callout cpu. 251 */ 252 static int 253 cc_cce_migrating(struct callout_cpu *cc, int direct) 254 { 255 256 #ifdef SMP 257 return (cc_migration_cpu(cc, direct) != CPUBLOCK); 258 #else 259 return (0); 260 #endif 261 } 262 263 /* 264 * Kernel low level callwheel initialization 265 * called on cpu0 during kernel startup. 266 */ 267 static void 268 callout_callwheel_init(void *dummy) 269 { 270 struct callout_cpu *cc; 271 272 /* 273 * Calculate the size of the callout wheel and the preallocated 274 * timeout() structures. 275 * XXX: Clip callout to result of previous function of maxusers 276 * maximum 384. This is still huge, but acceptable. 277 */ 278 memset(CC_CPU(0), 0, sizeof(cc_cpu)); 279 ncallout = imin(16 + maxproc + maxfiles, 18508); 280 TUNABLE_INT_FETCH("kern.ncallout", &ncallout); 281 282 /* 283 * Calculate callout wheel size, should be next power of two higher 284 * than 'ncallout'. 285 */ 286 callwheelsize = 1 << fls(ncallout); 287 callwheelmask = callwheelsize - 1; 288 289 /* 290 * Fetch whether we're pinning the swi's or not. 291 */ 292 TUNABLE_INT_FETCH("kern.pin_default_swi", &pin_default_swi); 293 TUNABLE_INT_FETCH("kern.pin_pcpu_swi", &pin_pcpu_swi); 294 295 /* 296 * Only cpu0 handles timeout(9) and receives a preallocation. 297 * 298 * XXX: Once all timeout(9) consumers are converted this can 299 * be removed. 300 */ 301 timeout_cpu = PCPU_GET(cpuid); 302 cc = CC_CPU(timeout_cpu); 303 cc->cc_callout = malloc(ncallout * sizeof(struct callout), 304 M_CALLOUT, M_WAITOK); 305 callout_cpu_init(cc, timeout_cpu); 306 } 307 SYSINIT(callwheel_init, SI_SUB_CPU, SI_ORDER_ANY, callout_callwheel_init, NULL); 308 309 /* 310 * Initialize the per-cpu callout structures. 311 */ 312 static void 313 callout_cpu_init(struct callout_cpu *cc, int cpu) 314 { 315 struct callout *c; 316 int i; 317 318 mtx_init(&cc->cc_lock, "callout", NULL, MTX_SPIN | MTX_RECURSE); 319 SLIST_INIT(&cc->cc_callfree); 320 cc->cc_inited = 1; 321 cc->cc_callwheel = malloc(sizeof(struct callout_list) * callwheelsize, 322 M_CALLOUT, M_WAITOK); 323 for (i = 0; i < callwheelsize; i++) 324 LIST_INIT(&cc->cc_callwheel[i]); 325 TAILQ_INIT(&cc->cc_expireq); 326 cc->cc_firstevent = SBT_MAX; 327 for (i = 0; i < 2; i++) 328 cc_cce_cleanup(cc, i); 329 snprintf(cc->cc_ktr_event_name, sizeof(cc->cc_ktr_event_name), 330 "callwheel cpu %d", cpu); 331 if (cc->cc_callout == NULL) /* Only cpu0 handles timeout(9) */ 332 return; 333 for (i = 0; i < ncallout; i++) { 334 c = &cc->cc_callout[i]; 335 callout_init(c, 0); 336 c->c_iflags = CALLOUT_LOCAL_ALLOC; 337 SLIST_INSERT_HEAD(&cc->cc_callfree, c, c_links.sle); 338 } 339 } 340 341 #ifdef SMP 342 /* 343 * Switches the cpu tied to a specific callout. 344 * The function expects a locked incoming callout cpu and returns with 345 * locked outcoming callout cpu. 346 */ 347 static struct callout_cpu * 348 callout_cpu_switch(struct callout *c, struct callout_cpu *cc, int new_cpu) 349 { 350 struct callout_cpu *new_cc; 351 352 MPASS(c != NULL && cc != NULL); 353 CC_LOCK_ASSERT(cc); 354 355 /* 356 * Avoid interrupts and preemption firing after the callout cpu 357 * is blocked in order to avoid deadlocks as the new thread 358 * may be willing to acquire the callout cpu lock. 359 */ 360 c->c_cpu = CPUBLOCK; 361 spinlock_enter(); 362 CC_UNLOCK(cc); 363 new_cc = CC_CPU(new_cpu); 364 CC_LOCK(new_cc); 365 spinlock_exit(); 366 c->c_cpu = new_cpu; 367 return (new_cc); 368 } 369 #endif 370 371 /* 372 * Start standard softclock thread. 373 */ 374 static void 375 start_softclock(void *dummy) 376 { 377 struct callout_cpu *cc; 378 char name[MAXCOMLEN]; 379 #ifdef SMP 380 int cpu; 381 struct intr_event *ie; 382 #endif 383 384 cc = CC_CPU(timeout_cpu); 385 snprintf(name, sizeof(name), "clock (%d)", timeout_cpu); 386 if (swi_add(&clk_intr_event, name, softclock, cc, SWI_CLOCK, 387 INTR_MPSAFE, &cc->cc_cookie)) 388 panic("died while creating standard software ithreads"); 389 if (pin_default_swi && 390 (intr_event_bind(clk_intr_event, timeout_cpu) != 0)) { 391 printf("%s: timeout clock couldn't be pinned to cpu %d\n", 392 __func__, 393 timeout_cpu); 394 } 395 396 #ifdef SMP 397 CPU_FOREACH(cpu) { 398 if (cpu == timeout_cpu) 399 continue; 400 cc = CC_CPU(cpu); 401 cc->cc_callout = NULL; /* Only cpu0 handles timeout(9). */ 402 callout_cpu_init(cc, cpu); 403 snprintf(name, sizeof(name), "clock (%d)", cpu); 404 ie = NULL; 405 if (swi_add(&ie, name, softclock, cc, SWI_CLOCK, 406 INTR_MPSAFE, &cc->cc_cookie)) 407 panic("died while creating standard software ithreads"); 408 if (pin_pcpu_swi && (intr_event_bind(ie, cpu) != 0)) { 409 printf("%s: per-cpu clock couldn't be pinned to " 410 "cpu %d\n", 411 __func__, 412 cpu); 413 } 414 } 415 #endif 416 } 417 SYSINIT(start_softclock, SI_SUB_SOFTINTR, SI_ORDER_FIRST, start_softclock, NULL); 418 419 #define CC_HASH_SHIFT 8 420 421 static inline u_int 422 callout_hash(sbintime_t sbt) 423 { 424 425 return (sbt >> (32 - CC_HASH_SHIFT)); 426 } 427 428 static inline u_int 429 callout_get_bucket(sbintime_t sbt) 430 { 431 432 return (callout_hash(sbt) & callwheelmask); 433 } 434 435 void 436 callout_process(sbintime_t now) 437 { 438 struct callout *tmp, *tmpn; 439 struct callout_cpu *cc; 440 struct callout_list *sc; 441 sbintime_t first, last, max, tmp_max; 442 uint32_t lookahead; 443 u_int firstb, lastb, nowb; 444 #ifdef CALLOUT_PROFILING 445 int depth_dir = 0, mpcalls_dir = 0, lockcalls_dir = 0; 446 #endif 447 448 cc = CC_SELF(); 449 mtx_lock_spin_flags(&cc->cc_lock, MTX_QUIET); 450 451 /* Compute the buckets of the last scan and present times. */ 452 firstb = callout_hash(cc->cc_lastscan); 453 cc->cc_lastscan = now; 454 nowb = callout_hash(now); 455 456 /* Compute the last bucket and minimum time of the bucket after it. */ 457 if (nowb == firstb) 458 lookahead = (SBT_1S / 16); 459 else if (nowb - firstb == 1) 460 lookahead = (SBT_1S / 8); 461 else 462 lookahead = (SBT_1S / 2); 463 first = last = now; 464 first += (lookahead / 2); 465 last += lookahead; 466 last &= (0xffffffffffffffffLLU << (32 - CC_HASH_SHIFT)); 467 lastb = callout_hash(last) - 1; 468 max = last; 469 470 /* 471 * Check if we wrapped around the entire wheel from the last scan. 472 * In case, we need to scan entirely the wheel for pending callouts. 473 */ 474 if (lastb - firstb >= callwheelsize) { 475 lastb = firstb + callwheelsize - 1; 476 if (nowb - firstb >= callwheelsize) 477 nowb = lastb; 478 } 479 480 /* Iterate callwheel from firstb to nowb and then up to lastb. */ 481 do { 482 sc = &cc->cc_callwheel[firstb & callwheelmask]; 483 tmp = LIST_FIRST(sc); 484 while (tmp != NULL) { 485 /* Run the callout if present time within allowed. */ 486 if (tmp->c_time <= now) { 487 /* 488 * Consumer told us the callout may be run 489 * directly from hardware interrupt context. 490 */ 491 if (tmp->c_iflags & CALLOUT_DIRECT) { 492 #ifdef CALLOUT_PROFILING 493 ++depth_dir; 494 #endif 495 cc_exec_next(cc) = 496 LIST_NEXT(tmp, c_links.le); 497 cc->cc_bucket = firstb & callwheelmask; 498 LIST_REMOVE(tmp, c_links.le); 499 softclock_call_cc(tmp, cc, 500 #ifdef CALLOUT_PROFILING 501 &mpcalls_dir, &lockcalls_dir, NULL, 502 #endif 503 1); 504 tmp = cc_exec_next(cc); 505 cc_exec_next(cc) = NULL; 506 } else { 507 tmpn = LIST_NEXT(tmp, c_links.le); 508 LIST_REMOVE(tmp, c_links.le); 509 TAILQ_INSERT_TAIL(&cc->cc_expireq, 510 tmp, c_links.tqe); 511 tmp->c_iflags |= CALLOUT_PROCESSED; 512 tmp = tmpn; 513 } 514 continue; 515 } 516 /* Skip events from distant future. */ 517 if (tmp->c_time >= max) 518 goto next; 519 /* 520 * Event minimal time is bigger than present maximal 521 * time, so it cannot be aggregated. 522 */ 523 if (tmp->c_time > last) { 524 lastb = nowb; 525 goto next; 526 } 527 /* Update first and last time, respecting this event. */ 528 if (tmp->c_time < first) 529 first = tmp->c_time; 530 tmp_max = tmp->c_time + tmp->c_precision; 531 if (tmp_max < last) 532 last = tmp_max; 533 next: 534 tmp = LIST_NEXT(tmp, c_links.le); 535 } 536 /* Proceed with the next bucket. */ 537 firstb++; 538 /* 539 * Stop if we looked after present time and found 540 * some event we can't execute at now. 541 * Stop if we looked far enough into the future. 542 */ 543 } while (((int)(firstb - lastb)) <= 0); 544 cc->cc_firstevent = last; 545 #ifndef NO_EVENTTIMERS 546 cpu_new_callout(curcpu, last, first); 547 #endif 548 #ifdef CALLOUT_PROFILING 549 avg_depth_dir += (depth_dir * 1000 - avg_depth_dir) >> 8; 550 avg_mpcalls_dir += (mpcalls_dir * 1000 - avg_mpcalls_dir) >> 8; 551 avg_lockcalls_dir += (lockcalls_dir * 1000 - avg_lockcalls_dir) >> 8; 552 #endif 553 mtx_unlock_spin_flags(&cc->cc_lock, MTX_QUIET); 554 /* 555 * swi_sched acquires the thread lock, so we don't want to call it 556 * with cc_lock held; incorrect locking order. 557 */ 558 if (!TAILQ_EMPTY(&cc->cc_expireq)) 559 swi_sched(cc->cc_cookie, 0); 560 } 561 562 static struct callout_cpu * 563 callout_lock(struct callout *c) 564 { 565 struct callout_cpu *cc; 566 int cpu; 567 568 for (;;) { 569 cpu = c->c_cpu; 570 #ifdef SMP 571 if (cpu == CPUBLOCK) { 572 while (c->c_cpu == CPUBLOCK) 573 cpu_spinwait(); 574 continue; 575 } 576 #endif 577 cc = CC_CPU(cpu); 578 CC_LOCK(cc); 579 if (cpu == c->c_cpu) 580 break; 581 CC_UNLOCK(cc); 582 } 583 return (cc); 584 } 585 586 static void 587 callout_cc_add(struct callout *c, struct callout_cpu *cc, 588 sbintime_t sbt, sbintime_t precision, void (*func)(void *), 589 void *arg, int cpu, int flags) 590 { 591 int bucket; 592 593 CC_LOCK_ASSERT(cc); 594 if (sbt < cc->cc_lastscan) 595 sbt = cc->cc_lastscan; 596 c->c_arg = arg; 597 c->c_iflags |= CALLOUT_PENDING; 598 c->c_iflags &= ~CALLOUT_PROCESSED; 599 c->c_flags |= CALLOUT_ACTIVE; 600 if (flags & C_DIRECT_EXEC) 601 c->c_iflags |= CALLOUT_DIRECT; 602 c->c_func = func; 603 c->c_time = sbt; 604 c->c_precision = precision; 605 bucket = callout_get_bucket(c->c_time); 606 CTR3(KTR_CALLOUT, "precision set for %p: %d.%08x", 607 c, (int)(c->c_precision >> 32), 608 (u_int)(c->c_precision & 0xffffffff)); 609 LIST_INSERT_HEAD(&cc->cc_callwheel[bucket], c, c_links.le); 610 if (cc->cc_bucket == bucket) 611 cc_exec_next(cc) = c; 612 #ifndef NO_EVENTTIMERS 613 /* 614 * Inform the eventtimers(4) subsystem there's a new callout 615 * that has been inserted, but only if really required. 616 */ 617 if (SBT_MAX - c->c_time < c->c_precision) 618 c->c_precision = SBT_MAX - c->c_time; 619 sbt = c->c_time + c->c_precision; 620 if (sbt < cc->cc_firstevent) { 621 cc->cc_firstevent = sbt; 622 cpu_new_callout(cpu, sbt, c->c_time); 623 } 624 #endif 625 } 626 627 static void 628 callout_cc_del(struct callout *c, struct callout_cpu *cc) 629 { 630 631 if ((c->c_iflags & CALLOUT_LOCAL_ALLOC) == 0) 632 return; 633 c->c_func = NULL; 634 SLIST_INSERT_HEAD(&cc->cc_callfree, c, c_links.sle); 635 } 636 637 static void 638 softclock_call_cc(struct callout *c, struct callout_cpu *cc, 639 #ifdef CALLOUT_PROFILING 640 int *mpcalls, int *lockcalls, int *gcalls, 641 #endif 642 int direct) 643 { 644 struct rm_priotracker tracker; 645 void (*c_func)(void *); 646 void *c_arg; 647 struct lock_class *class; 648 struct lock_object *c_lock; 649 uintptr_t lock_status; 650 int c_iflags; 651 #ifdef SMP 652 struct callout_cpu *new_cc; 653 void (*new_func)(void *); 654 void *new_arg; 655 int flags, new_cpu; 656 sbintime_t new_prec, new_time; 657 #endif 658 #if defined(DIAGNOSTIC) || defined(CALLOUT_PROFILING) 659 sbintime_t sbt1, sbt2; 660 struct timespec ts2; 661 static sbintime_t maxdt = 2 * SBT_1MS; /* 2 msec */ 662 static timeout_t *lastfunc; 663 #endif 664 665 KASSERT((c->c_iflags & CALLOUT_PENDING) == CALLOUT_PENDING, 666 ("softclock_call_cc: pend %p %x", c, c->c_iflags)); 667 KASSERT((c->c_flags & CALLOUT_ACTIVE) == CALLOUT_ACTIVE, 668 ("softclock_call_cc: act %p %x", c, c->c_flags)); 669 class = (c->c_lock != NULL) ? LOCK_CLASS(c->c_lock) : NULL; 670 lock_status = 0; 671 if (c->c_flags & CALLOUT_SHAREDLOCK) { 672 if (class == &lock_class_rm) 673 lock_status = (uintptr_t)&tracker; 674 else 675 lock_status = 1; 676 } 677 c_lock = c->c_lock; 678 c_func = c->c_func; 679 c_arg = c->c_arg; 680 c_iflags = c->c_iflags; 681 if (c->c_iflags & CALLOUT_LOCAL_ALLOC) 682 c->c_iflags = CALLOUT_LOCAL_ALLOC; 683 else 684 c->c_iflags &= ~CALLOUT_PENDING; 685 686 cc_exec_curr(cc, direct) = c; 687 cc_exec_cancel(cc, direct) = false; 688 cc_exec_drain(cc, direct) = NULL; 689 CC_UNLOCK(cc); 690 if (c_lock != NULL) { 691 class->lc_lock(c_lock, lock_status); 692 /* 693 * The callout may have been cancelled 694 * while we switched locks. 695 */ 696 if (cc_exec_cancel(cc, direct)) { 697 class->lc_unlock(c_lock); 698 goto skip; 699 } 700 /* The callout cannot be stopped now. */ 701 cc_exec_cancel(cc, direct) = true; 702 if (c_lock == &Giant.lock_object) { 703 #ifdef CALLOUT_PROFILING 704 (*gcalls)++; 705 #endif 706 CTR3(KTR_CALLOUT, "callout giant %p func %p arg %p", 707 c, c_func, c_arg); 708 } else { 709 #ifdef CALLOUT_PROFILING 710 (*lockcalls)++; 711 #endif 712 CTR3(KTR_CALLOUT, "callout lock %p func %p arg %p", 713 c, c_func, c_arg); 714 } 715 } else { 716 #ifdef CALLOUT_PROFILING 717 (*mpcalls)++; 718 #endif 719 CTR3(KTR_CALLOUT, "callout %p func %p arg %p", 720 c, c_func, c_arg); 721 } 722 KTR_STATE3(KTR_SCHED, "callout", cc->cc_ktr_event_name, "running", 723 "func:%p", c_func, "arg:%p", c_arg, "direct:%d", direct); 724 #if defined(DIAGNOSTIC) || defined(CALLOUT_PROFILING) 725 sbt1 = sbinuptime(); 726 #endif 727 THREAD_NO_SLEEPING(); 728 SDT_PROBE1(callout_execute, , , callout__start, c); 729 c_func(c_arg); 730 SDT_PROBE1(callout_execute, , , callout__end, c); 731 THREAD_SLEEPING_OK(); 732 #if defined(DIAGNOSTIC) || defined(CALLOUT_PROFILING) 733 sbt2 = sbinuptime(); 734 sbt2 -= sbt1; 735 if (sbt2 > maxdt) { 736 if (lastfunc != c_func || sbt2 > maxdt * 2) { 737 ts2 = sbttots(sbt2); 738 printf( 739 "Expensive timeout(9) function: %p(%p) %jd.%09ld s\n", 740 c_func, c_arg, (intmax_t)ts2.tv_sec, ts2.tv_nsec); 741 } 742 maxdt = sbt2; 743 lastfunc = c_func; 744 } 745 #endif 746 KTR_STATE0(KTR_SCHED, "callout", cc->cc_ktr_event_name, "idle"); 747 CTR1(KTR_CALLOUT, "callout %p finished", c); 748 if ((c_iflags & CALLOUT_RETURNUNLOCKED) == 0) 749 class->lc_unlock(c_lock); 750 skip: 751 CC_LOCK(cc); 752 KASSERT(cc_exec_curr(cc, direct) == c, ("mishandled cc_curr")); 753 cc_exec_curr(cc, direct) = NULL; 754 if (cc_exec_drain(cc, direct)) { 755 void (*drain)(void *); 756 757 drain = cc_exec_drain(cc, direct); 758 cc_exec_drain(cc, direct) = NULL; 759 CC_UNLOCK(cc); 760 drain(c_arg); 761 CC_LOCK(cc); 762 } 763 if (cc_exec_waiting(cc, direct)) { 764 /* 765 * There is someone waiting for the 766 * callout to complete. 767 * If the callout was scheduled for 768 * migration just cancel it. 769 */ 770 if (cc_cce_migrating(cc, direct)) { 771 cc_cce_cleanup(cc, direct); 772 773 /* 774 * It should be assert here that the callout is not 775 * destroyed but that is not easy. 776 */ 777 c->c_iflags &= ~CALLOUT_DFRMIGRATION; 778 } 779 cc_exec_waiting(cc, direct) = false; 780 CC_UNLOCK(cc); 781 wakeup(&cc_exec_waiting(cc, direct)); 782 CC_LOCK(cc); 783 } else if (cc_cce_migrating(cc, direct)) { 784 KASSERT((c_iflags & CALLOUT_LOCAL_ALLOC) == 0, 785 ("Migrating legacy callout %p", c)); 786 #ifdef SMP 787 /* 788 * If the callout was scheduled for 789 * migration just perform it now. 790 */ 791 new_cpu = cc_migration_cpu(cc, direct); 792 new_time = cc_migration_time(cc, direct); 793 new_prec = cc_migration_prec(cc, direct); 794 new_func = cc_migration_func(cc, direct); 795 new_arg = cc_migration_arg(cc, direct); 796 cc_cce_cleanup(cc, direct); 797 798 /* 799 * It should be assert here that the callout is not destroyed 800 * but that is not easy. 801 * 802 * As first thing, handle deferred callout stops. 803 */ 804 if (!callout_migrating(c)) { 805 CTR3(KTR_CALLOUT, 806 "deferred cancelled %p func %p arg %p", 807 c, new_func, new_arg); 808 callout_cc_del(c, cc); 809 return; 810 } 811 c->c_iflags &= ~CALLOUT_DFRMIGRATION; 812 813 new_cc = callout_cpu_switch(c, cc, new_cpu); 814 flags = (direct) ? C_DIRECT_EXEC : 0; 815 callout_cc_add(c, new_cc, new_time, new_prec, new_func, 816 new_arg, new_cpu, flags); 817 CC_UNLOCK(new_cc); 818 CC_LOCK(cc); 819 #else 820 panic("migration should not happen"); 821 #endif 822 } 823 /* 824 * If the current callout is locally allocated (from 825 * timeout(9)) then put it on the freelist. 826 * 827 * Note: we need to check the cached copy of c_iflags because 828 * if it was not local, then it's not safe to deref the 829 * callout pointer. 830 */ 831 KASSERT((c_iflags & CALLOUT_LOCAL_ALLOC) == 0 || 832 c->c_iflags == CALLOUT_LOCAL_ALLOC, 833 ("corrupted callout")); 834 if (c_iflags & CALLOUT_LOCAL_ALLOC) 835 callout_cc_del(c, cc); 836 } 837 838 /* 839 * The callout mechanism is based on the work of Adam M. Costello and 840 * George Varghese, published in a technical report entitled "Redesigning 841 * the BSD Callout and Timer Facilities" and modified slightly for inclusion 842 * in FreeBSD by Justin T. Gibbs. The original work on the data structures 843 * used in this implementation was published by G. Varghese and T. Lauck in 844 * the paper "Hashed and Hierarchical Timing Wheels: Data Structures for 845 * the Efficient Implementation of a Timer Facility" in the Proceedings of 846 * the 11th ACM Annual Symposium on Operating Systems Principles, 847 * Austin, Texas Nov 1987. 848 */ 849 850 /* 851 * Software (low priority) clock interrupt. 852 * Run periodic events from timeout queue. 853 */ 854 void 855 softclock(void *arg) 856 { 857 struct callout_cpu *cc; 858 struct callout *c; 859 #ifdef CALLOUT_PROFILING 860 int depth = 0, gcalls = 0, lockcalls = 0, mpcalls = 0; 861 #endif 862 863 cc = (struct callout_cpu *)arg; 864 CC_LOCK(cc); 865 while ((c = TAILQ_FIRST(&cc->cc_expireq)) != NULL) { 866 TAILQ_REMOVE(&cc->cc_expireq, c, c_links.tqe); 867 softclock_call_cc(c, cc, 868 #ifdef CALLOUT_PROFILING 869 &mpcalls, &lockcalls, &gcalls, 870 #endif 871 0); 872 #ifdef CALLOUT_PROFILING 873 ++depth; 874 #endif 875 } 876 #ifdef CALLOUT_PROFILING 877 avg_depth += (depth * 1000 - avg_depth) >> 8; 878 avg_mpcalls += (mpcalls * 1000 - avg_mpcalls) >> 8; 879 avg_lockcalls += (lockcalls * 1000 - avg_lockcalls) >> 8; 880 avg_gcalls += (gcalls * 1000 - avg_gcalls) >> 8; 881 #endif 882 CC_UNLOCK(cc); 883 } 884 885 /* 886 * timeout -- 887 * Execute a function after a specified length of time. 888 * 889 * untimeout -- 890 * Cancel previous timeout function call. 891 * 892 * callout_handle_init -- 893 * Initialize a handle so that using it with untimeout is benign. 894 * 895 * See AT&T BCI Driver Reference Manual for specification. This 896 * implementation differs from that one in that although an 897 * identification value is returned from timeout, the original 898 * arguments to timeout as well as the identifier are used to 899 * identify entries for untimeout. 900 */ 901 struct callout_handle 902 timeout(timeout_t *ftn, void *arg, int to_ticks) 903 { 904 struct callout_cpu *cc; 905 struct callout *new; 906 struct callout_handle handle; 907 908 cc = CC_CPU(timeout_cpu); 909 CC_LOCK(cc); 910 /* Fill in the next free callout structure. */ 911 new = SLIST_FIRST(&cc->cc_callfree); 912 if (new == NULL) 913 /* XXX Attempt to malloc first */ 914 panic("timeout table full"); 915 SLIST_REMOVE_HEAD(&cc->cc_callfree, c_links.sle); 916 callout_reset(new, to_ticks, ftn, arg); 917 handle.callout = new; 918 CC_UNLOCK(cc); 919 920 return (handle); 921 } 922 923 void 924 untimeout(timeout_t *ftn, void *arg, struct callout_handle handle) 925 { 926 struct callout_cpu *cc; 927 928 /* 929 * Check for a handle that was initialized 930 * by callout_handle_init, but never used 931 * for a real timeout. 932 */ 933 if (handle.callout == NULL) 934 return; 935 936 cc = callout_lock(handle.callout); 937 if (handle.callout->c_func == ftn && handle.callout->c_arg == arg) 938 callout_stop(handle.callout); 939 CC_UNLOCK(cc); 940 } 941 942 void 943 callout_handle_init(struct callout_handle *handle) 944 { 945 handle->callout = NULL; 946 } 947 948 void 949 callout_when(sbintime_t sbt, sbintime_t precision, int flags, 950 sbintime_t *res, sbintime_t *prec_res) 951 { 952 sbintime_t to_sbt, to_pr; 953 954 if ((flags & (C_ABSOLUTE | C_PRECALC)) != 0) { 955 *res = sbt; 956 *prec_res = precision; 957 return; 958 } 959 if ((flags & C_HARDCLOCK) != 0 && sbt < tick_sbt) 960 sbt = tick_sbt; 961 if ((flags & C_HARDCLOCK) != 0 || 962 #ifdef NO_EVENTTIMERS 963 sbt >= sbt_timethreshold) { 964 to_sbt = getsbinuptime(); 965 966 /* Add safety belt for the case of hz > 1000. */ 967 to_sbt += tc_tick_sbt - tick_sbt; 968 #else 969 sbt >= sbt_tickthreshold) { 970 /* 971 * Obtain the time of the last hardclock() call on 972 * this CPU directly from the kern_clocksource.c. 973 * This value is per-CPU, but it is equal for all 974 * active ones. 975 */ 976 #ifdef __LP64__ 977 to_sbt = DPCPU_GET(hardclocktime); 978 #else 979 spinlock_enter(); 980 to_sbt = DPCPU_GET(hardclocktime); 981 spinlock_exit(); 982 #endif 983 #endif 984 if (cold && to_sbt == 0) 985 to_sbt = sbinuptime(); 986 if ((flags & C_HARDCLOCK) == 0) 987 to_sbt += tick_sbt; 988 } else 989 to_sbt = sbinuptime(); 990 if (SBT_MAX - to_sbt < sbt) 991 to_sbt = SBT_MAX; 992 else 993 to_sbt += sbt; 994 *res = to_sbt; 995 to_pr = ((C_PRELGET(flags) < 0) ? sbt >> tc_precexp : 996 sbt >> C_PRELGET(flags)); 997 *prec_res = to_pr > precision ? to_pr : precision; 998 } 999 1000 /* 1001 * New interface; clients allocate their own callout structures. 1002 * 1003 * callout_reset() - establish or change a timeout 1004 * callout_stop() - disestablish a timeout 1005 * callout_init() - initialize a callout structure so that it can 1006 * safely be passed to callout_reset() and callout_stop() 1007 * 1008 * <sys/callout.h> defines three convenience macros: 1009 * 1010 * callout_active() - returns truth if callout has not been stopped, 1011 * drained, or deactivated since the last time the callout was 1012 * reset. 1013 * callout_pending() - returns truth if callout is still waiting for timeout 1014 * callout_deactivate() - marks the callout as having been serviced 1015 */ 1016 int 1017 callout_reset_sbt_on(struct callout *c, sbintime_t sbt, sbintime_t prec, 1018 void (*ftn)(void *), void *arg, int cpu, int flags) 1019 { 1020 sbintime_t to_sbt, precision; 1021 struct callout_cpu *cc; 1022 int cancelled, direct; 1023 int ignore_cpu=0; 1024 1025 cancelled = 0; 1026 if (cpu == -1) { 1027 ignore_cpu = 1; 1028 } else if ((cpu >= MAXCPU) || 1029 ((CC_CPU(cpu))->cc_inited == 0)) { 1030 /* Invalid CPU spec */ 1031 panic("Invalid CPU in callout %d", cpu); 1032 } 1033 callout_when(sbt, prec, flags, &to_sbt, &precision); 1034 1035 /* 1036 * This flag used to be added by callout_cc_add, but the 1037 * first time you call this we could end up with the 1038 * wrong direct flag if we don't do it before we add. 1039 */ 1040 if (flags & C_DIRECT_EXEC) { 1041 direct = 1; 1042 } else { 1043 direct = 0; 1044 } 1045 KASSERT(!direct || c->c_lock == NULL, 1046 ("%s: direct callout %p has lock", __func__, c)); 1047 cc = callout_lock(c); 1048 /* 1049 * Don't allow migration of pre-allocated callouts lest they 1050 * become unbalanced or handle the case where the user does 1051 * not care. 1052 */ 1053 if ((c->c_iflags & CALLOUT_LOCAL_ALLOC) || 1054 ignore_cpu) { 1055 cpu = c->c_cpu; 1056 } 1057 1058 if (cc_exec_curr(cc, direct) == c) { 1059 /* 1060 * We're being asked to reschedule a callout which is 1061 * currently in progress. If there is a lock then we 1062 * can cancel the callout if it has not really started. 1063 */ 1064 if (c->c_lock != NULL && !cc_exec_cancel(cc, direct)) 1065 cancelled = cc_exec_cancel(cc, direct) = true; 1066 if (cc_exec_waiting(cc, direct)) { 1067 /* 1068 * Someone has called callout_drain to kill this 1069 * callout. Don't reschedule. 1070 */ 1071 CTR4(KTR_CALLOUT, "%s %p func %p arg %p", 1072 cancelled ? "cancelled" : "failed to cancel", 1073 c, c->c_func, c->c_arg); 1074 CC_UNLOCK(cc); 1075 return (cancelled); 1076 } 1077 #ifdef SMP 1078 if (callout_migrating(c)) { 1079 /* 1080 * This only occurs when a second callout_reset_sbt_on 1081 * is made after a previous one moved it into 1082 * deferred migration (below). Note we do *not* change 1083 * the prev_cpu even though the previous target may 1084 * be different. 1085 */ 1086 cc_migration_cpu(cc, direct) = cpu; 1087 cc_migration_time(cc, direct) = to_sbt; 1088 cc_migration_prec(cc, direct) = precision; 1089 cc_migration_func(cc, direct) = ftn; 1090 cc_migration_arg(cc, direct) = arg; 1091 cancelled = 1; 1092 CC_UNLOCK(cc); 1093 return (cancelled); 1094 } 1095 #endif 1096 } 1097 if (c->c_iflags & CALLOUT_PENDING) { 1098 if ((c->c_iflags & CALLOUT_PROCESSED) == 0) { 1099 if (cc_exec_next(cc) == c) 1100 cc_exec_next(cc) = LIST_NEXT(c, c_links.le); 1101 LIST_REMOVE(c, c_links.le); 1102 } else { 1103 TAILQ_REMOVE(&cc->cc_expireq, c, c_links.tqe); 1104 } 1105 cancelled = 1; 1106 c->c_iflags &= ~ CALLOUT_PENDING; 1107 c->c_flags &= ~ CALLOUT_ACTIVE; 1108 } 1109 1110 #ifdef SMP 1111 /* 1112 * If the callout must migrate try to perform it immediately. 1113 * If the callout is currently running, just defer the migration 1114 * to a more appropriate moment. 1115 */ 1116 if (c->c_cpu != cpu) { 1117 if (cc_exec_curr(cc, direct) == c) { 1118 /* 1119 * Pending will have been removed since we are 1120 * actually executing the callout on another 1121 * CPU. That callout should be waiting on the 1122 * lock the caller holds. If we set both 1123 * active/and/pending after we return and the 1124 * lock on the executing callout proceeds, it 1125 * will then see pending is true and return. 1126 * At the return from the actual callout execution 1127 * the migration will occur in softclock_call_cc 1128 * and this new callout will be placed on the 1129 * new CPU via a call to callout_cpu_switch() which 1130 * will get the lock on the right CPU followed 1131 * by a call callout_cc_add() which will add it there. 1132 * (see above in softclock_call_cc()). 1133 */ 1134 cc_migration_cpu(cc, direct) = cpu; 1135 cc_migration_time(cc, direct) = to_sbt; 1136 cc_migration_prec(cc, direct) = precision; 1137 cc_migration_func(cc, direct) = ftn; 1138 cc_migration_arg(cc, direct) = arg; 1139 c->c_iflags |= (CALLOUT_DFRMIGRATION | CALLOUT_PENDING); 1140 c->c_flags |= CALLOUT_ACTIVE; 1141 CTR6(KTR_CALLOUT, 1142 "migration of %p func %p arg %p in %d.%08x to %u deferred", 1143 c, c->c_func, c->c_arg, (int)(to_sbt >> 32), 1144 (u_int)(to_sbt & 0xffffffff), cpu); 1145 CC_UNLOCK(cc); 1146 return (cancelled); 1147 } 1148 cc = callout_cpu_switch(c, cc, cpu); 1149 } 1150 #endif 1151 1152 callout_cc_add(c, cc, to_sbt, precision, ftn, arg, cpu, flags); 1153 CTR6(KTR_CALLOUT, "%sscheduled %p func %p arg %p in %d.%08x", 1154 cancelled ? "re" : "", c, c->c_func, c->c_arg, (int)(to_sbt >> 32), 1155 (u_int)(to_sbt & 0xffffffff)); 1156 CC_UNLOCK(cc); 1157 1158 return (cancelled); 1159 } 1160 1161 /* 1162 * Common idioms that can be optimized in the future. 1163 */ 1164 int 1165 callout_schedule_on(struct callout *c, int to_ticks, int cpu) 1166 { 1167 return callout_reset_on(c, to_ticks, c->c_func, c->c_arg, cpu); 1168 } 1169 1170 int 1171 callout_schedule(struct callout *c, int to_ticks) 1172 { 1173 return callout_reset_on(c, to_ticks, c->c_func, c->c_arg, c->c_cpu); 1174 } 1175 1176 int 1177 _callout_stop_safe(struct callout *c, int flags, void (*drain)(void *)) 1178 { 1179 struct callout_cpu *cc, *old_cc; 1180 struct lock_class *class; 1181 int direct, sq_locked, use_lock; 1182 int cancelled, not_on_a_list; 1183 1184 if ((flags & CS_DRAIN) != 0) 1185 WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, c->c_lock, 1186 "calling %s", __func__); 1187 1188 /* 1189 * Some old subsystems don't hold Giant while running a callout_stop(), 1190 * so just discard this check for the moment. 1191 */ 1192 if ((flags & CS_DRAIN) == 0 && c->c_lock != NULL) { 1193 if (c->c_lock == &Giant.lock_object) 1194 use_lock = mtx_owned(&Giant); 1195 else { 1196 use_lock = 1; 1197 class = LOCK_CLASS(c->c_lock); 1198 class->lc_assert(c->c_lock, LA_XLOCKED); 1199 } 1200 } else 1201 use_lock = 0; 1202 if (c->c_iflags & CALLOUT_DIRECT) { 1203 direct = 1; 1204 } else { 1205 direct = 0; 1206 } 1207 sq_locked = 0; 1208 old_cc = NULL; 1209 again: 1210 cc = callout_lock(c); 1211 1212 if ((c->c_iflags & (CALLOUT_DFRMIGRATION | CALLOUT_PENDING)) == 1213 (CALLOUT_DFRMIGRATION | CALLOUT_PENDING) && 1214 ((c->c_flags & CALLOUT_ACTIVE) == CALLOUT_ACTIVE)) { 1215 /* 1216 * Special case where this slipped in while we 1217 * were migrating *as* the callout is about to 1218 * execute. The caller probably holds the lock 1219 * the callout wants. 1220 * 1221 * Get rid of the migration first. Then set 1222 * the flag that tells this code *not* to 1223 * try to remove it from any lists (its not 1224 * on one yet). When the callout wheel runs, 1225 * it will ignore this callout. 1226 */ 1227 c->c_iflags &= ~CALLOUT_PENDING; 1228 c->c_flags &= ~CALLOUT_ACTIVE; 1229 not_on_a_list = 1; 1230 } else { 1231 not_on_a_list = 0; 1232 } 1233 1234 /* 1235 * If the callout was migrating while the callout cpu lock was 1236 * dropped, just drop the sleepqueue lock and check the states 1237 * again. 1238 */ 1239 if (sq_locked != 0 && cc != old_cc) { 1240 #ifdef SMP 1241 CC_UNLOCK(cc); 1242 sleepq_release(&cc_exec_waiting(old_cc, direct)); 1243 sq_locked = 0; 1244 old_cc = NULL; 1245 goto again; 1246 #else 1247 panic("migration should not happen"); 1248 #endif 1249 } 1250 1251 /* 1252 * If the callout is running, try to stop it or drain it. 1253 */ 1254 if (cc_exec_curr(cc, direct) == c) { 1255 /* 1256 * Succeed we to stop it or not, we must clear the 1257 * active flag - this is what API users expect. If we're 1258 * draining and the callout is currently executing, first wait 1259 * until it finishes. 1260 */ 1261 if ((flags & CS_DRAIN) == 0) 1262 c->c_flags &= ~CALLOUT_ACTIVE; 1263 1264 if ((flags & CS_DRAIN) != 0) { 1265 /* 1266 * The current callout is running (or just 1267 * about to run) and blocking is allowed, so 1268 * just wait for the current invocation to 1269 * finish. 1270 */ 1271 while (cc_exec_curr(cc, direct) == c) { 1272 /* 1273 * Use direct calls to sleepqueue interface 1274 * instead of cv/msleep in order to avoid 1275 * a LOR between cc_lock and sleepqueue 1276 * chain spinlocks. This piece of code 1277 * emulates a msleep_spin() call actually. 1278 * 1279 * If we already have the sleepqueue chain 1280 * locked, then we can safely block. If we 1281 * don't already have it locked, however, 1282 * we have to drop the cc_lock to lock 1283 * it. This opens several races, so we 1284 * restart at the beginning once we have 1285 * both locks. If nothing has changed, then 1286 * we will end up back here with sq_locked 1287 * set. 1288 */ 1289 if (!sq_locked) { 1290 CC_UNLOCK(cc); 1291 sleepq_lock( 1292 &cc_exec_waiting(cc, direct)); 1293 sq_locked = 1; 1294 old_cc = cc; 1295 goto again; 1296 } 1297 1298 /* 1299 * Migration could be cancelled here, but 1300 * as long as it is still not sure when it 1301 * will be packed up, just let softclock() 1302 * take care of it. 1303 */ 1304 cc_exec_waiting(cc, direct) = true; 1305 DROP_GIANT(); 1306 CC_UNLOCK(cc); 1307 sleepq_add( 1308 &cc_exec_waiting(cc, direct), 1309 &cc->cc_lock.lock_object, "codrain", 1310 SLEEPQ_SLEEP, 0); 1311 sleepq_wait( 1312 &cc_exec_waiting(cc, direct), 1313 0); 1314 sq_locked = 0; 1315 old_cc = NULL; 1316 1317 /* Reacquire locks previously released. */ 1318 PICKUP_GIANT(); 1319 CC_LOCK(cc); 1320 } 1321 c->c_flags &= ~CALLOUT_ACTIVE; 1322 } else if (use_lock && 1323 !cc_exec_cancel(cc, direct) && (drain == NULL)) { 1324 1325 /* 1326 * The current callout is waiting for its 1327 * lock which we hold. Cancel the callout 1328 * and return. After our caller drops the 1329 * lock, the callout will be skipped in 1330 * softclock(). This *only* works with a 1331 * callout_stop() *not* callout_drain() or 1332 * callout_async_drain(). 1333 */ 1334 cc_exec_cancel(cc, direct) = true; 1335 CTR3(KTR_CALLOUT, "cancelled %p func %p arg %p", 1336 c, c->c_func, c->c_arg); 1337 KASSERT(!cc_cce_migrating(cc, direct), 1338 ("callout wrongly scheduled for migration")); 1339 if (callout_migrating(c)) { 1340 c->c_iflags &= ~CALLOUT_DFRMIGRATION; 1341 #ifdef SMP 1342 cc_migration_cpu(cc, direct) = CPUBLOCK; 1343 cc_migration_time(cc, direct) = 0; 1344 cc_migration_prec(cc, direct) = 0; 1345 cc_migration_func(cc, direct) = NULL; 1346 cc_migration_arg(cc, direct) = NULL; 1347 #endif 1348 } 1349 CC_UNLOCK(cc); 1350 KASSERT(!sq_locked, ("sleepqueue chain locked")); 1351 return (1); 1352 } else if (callout_migrating(c)) { 1353 /* 1354 * The callout is currently being serviced 1355 * and the "next" callout is scheduled at 1356 * its completion with a migration. We remove 1357 * the migration flag so it *won't* get rescheduled, 1358 * but we can't stop the one thats running so 1359 * we return 0. 1360 */ 1361 c->c_iflags &= ~CALLOUT_DFRMIGRATION; 1362 #ifdef SMP 1363 /* 1364 * We can't call cc_cce_cleanup here since 1365 * if we do it will remove .ce_curr and 1366 * its still running. This will prevent a 1367 * reschedule of the callout when the 1368 * execution completes. 1369 */ 1370 cc_migration_cpu(cc, direct) = CPUBLOCK; 1371 cc_migration_time(cc, direct) = 0; 1372 cc_migration_prec(cc, direct) = 0; 1373 cc_migration_func(cc, direct) = NULL; 1374 cc_migration_arg(cc, direct) = NULL; 1375 #endif 1376 CTR3(KTR_CALLOUT, "postponing stop %p func %p arg %p", 1377 c, c->c_func, c->c_arg); 1378 if (drain) { 1379 cc_exec_drain(cc, direct) = drain; 1380 } 1381 CC_UNLOCK(cc); 1382 return ((flags & CS_EXECUTING) != 0); 1383 } 1384 CTR3(KTR_CALLOUT, "failed to stop %p func %p arg %p", 1385 c, c->c_func, c->c_arg); 1386 if (drain) { 1387 cc_exec_drain(cc, direct) = drain; 1388 } 1389 KASSERT(!sq_locked, ("sleepqueue chain still locked")); 1390 cancelled = ((flags & CS_EXECUTING) != 0); 1391 } else 1392 cancelled = 1; 1393 1394 if (sq_locked) 1395 sleepq_release(&cc_exec_waiting(cc, direct)); 1396 1397 if ((c->c_iflags & CALLOUT_PENDING) == 0) { 1398 CTR3(KTR_CALLOUT, "failed to stop %p func %p arg %p", 1399 c, c->c_func, c->c_arg); 1400 /* 1401 * For not scheduled and not executing callout return 1402 * negative value. 1403 */ 1404 if (cc_exec_curr(cc, direct) != c) 1405 cancelled = -1; 1406 CC_UNLOCK(cc); 1407 return (cancelled); 1408 } 1409 1410 c->c_iflags &= ~CALLOUT_PENDING; 1411 c->c_flags &= ~CALLOUT_ACTIVE; 1412 1413 CTR3(KTR_CALLOUT, "cancelled %p func %p arg %p", 1414 c, c->c_func, c->c_arg); 1415 if (not_on_a_list == 0) { 1416 if ((c->c_iflags & CALLOUT_PROCESSED) == 0) { 1417 if (cc_exec_next(cc) == c) 1418 cc_exec_next(cc) = LIST_NEXT(c, c_links.le); 1419 LIST_REMOVE(c, c_links.le); 1420 } else { 1421 TAILQ_REMOVE(&cc->cc_expireq, c, c_links.tqe); 1422 } 1423 } 1424 callout_cc_del(c, cc); 1425 CC_UNLOCK(cc); 1426 return (cancelled); 1427 } 1428 1429 void 1430 callout_init(struct callout *c, int mpsafe) 1431 { 1432 bzero(c, sizeof *c); 1433 if (mpsafe) { 1434 c->c_lock = NULL; 1435 c->c_iflags = CALLOUT_RETURNUNLOCKED; 1436 } else { 1437 c->c_lock = &Giant.lock_object; 1438 c->c_iflags = 0; 1439 } 1440 c->c_cpu = timeout_cpu; 1441 } 1442 1443 void 1444 _callout_init_lock(struct callout *c, struct lock_object *lock, int flags) 1445 { 1446 bzero(c, sizeof *c); 1447 c->c_lock = lock; 1448 KASSERT((flags & ~(CALLOUT_RETURNUNLOCKED | CALLOUT_SHAREDLOCK)) == 0, 1449 ("callout_init_lock: bad flags %d", flags)); 1450 KASSERT(lock != NULL || (flags & CALLOUT_RETURNUNLOCKED) == 0, 1451 ("callout_init_lock: CALLOUT_RETURNUNLOCKED with no lock")); 1452 KASSERT(lock == NULL || !(LOCK_CLASS(lock)->lc_flags & 1453 (LC_SPINLOCK | LC_SLEEPABLE)), ("%s: invalid lock class", 1454 __func__)); 1455 c->c_iflags = flags & (CALLOUT_RETURNUNLOCKED | CALLOUT_SHAREDLOCK); 1456 c->c_cpu = timeout_cpu; 1457 } 1458 1459 #ifdef APM_FIXUP_CALLTODO 1460 /* 1461 * Adjust the kernel calltodo timeout list. This routine is used after 1462 * an APM resume to recalculate the calltodo timer list values with the 1463 * number of hz's we have been sleeping. The next hardclock() will detect 1464 * that there are fired timers and run softclock() to execute them. 1465 * 1466 * Please note, I have not done an exhaustive analysis of what code this 1467 * might break. I am motivated to have my select()'s and alarm()'s that 1468 * have expired during suspend firing upon resume so that the applications 1469 * which set the timer can do the maintanence the timer was for as close 1470 * as possible to the originally intended time. Testing this code for a 1471 * week showed that resuming from a suspend resulted in 22 to 25 timers 1472 * firing, which seemed independent on whether the suspend was 2 hours or 1473 * 2 days. Your milage may vary. - Ken Key <key@cs.utk.edu> 1474 */ 1475 void 1476 adjust_timeout_calltodo(struct timeval *time_change) 1477 { 1478 struct callout *p; 1479 unsigned long delta_ticks; 1480 1481 /* 1482 * How many ticks were we asleep? 1483 * (stolen from tvtohz()). 1484 */ 1485 1486 /* Don't do anything */ 1487 if (time_change->tv_sec < 0) 1488 return; 1489 else if (time_change->tv_sec <= LONG_MAX / 1000000) 1490 delta_ticks = howmany(time_change->tv_sec * 1000000 + 1491 time_change->tv_usec, tick) + 1; 1492 else if (time_change->tv_sec <= LONG_MAX / hz) 1493 delta_ticks = time_change->tv_sec * hz + 1494 howmany(time_change->tv_usec, tick) + 1; 1495 else 1496 delta_ticks = LONG_MAX; 1497 1498 if (delta_ticks > INT_MAX) 1499 delta_ticks = INT_MAX; 1500 1501 /* 1502 * Now rip through the timer calltodo list looking for timers 1503 * to expire. 1504 */ 1505 1506 /* don't collide with softclock() */ 1507 CC_LOCK(cc); 1508 for (p = calltodo.c_next; p != NULL; p = p->c_next) { 1509 p->c_time -= delta_ticks; 1510 1511 /* Break if the timer had more time on it than delta_ticks */ 1512 if (p->c_time > 0) 1513 break; 1514 1515 /* take back the ticks the timer didn't use (p->c_time <= 0) */ 1516 delta_ticks = -p->c_time; 1517 } 1518 CC_UNLOCK(cc); 1519 1520 return; 1521 } 1522 #endif /* APM_FIXUP_CALLTODO */ 1523 1524 static int 1525 flssbt(sbintime_t sbt) 1526 { 1527 1528 sbt += (uint64_t)sbt >> 1; 1529 if (sizeof(long) >= sizeof(sbintime_t)) 1530 return (flsl(sbt)); 1531 if (sbt >= SBT_1S) 1532 return (flsl(((uint64_t)sbt) >> 32) + 32); 1533 return (flsl(sbt)); 1534 } 1535 1536 /* 1537 * Dump immediate statistic snapshot of the scheduled callouts. 1538 */ 1539 static int 1540 sysctl_kern_callout_stat(SYSCTL_HANDLER_ARGS) 1541 { 1542 struct callout *tmp; 1543 struct callout_cpu *cc; 1544 struct callout_list *sc; 1545 sbintime_t maxpr, maxt, medpr, medt, now, spr, st, t; 1546 int ct[64], cpr[64], ccpbk[32]; 1547 int error, val, i, count, tcum, pcum, maxc, c, medc; 1548 #ifdef SMP 1549 int cpu; 1550 #endif 1551 1552 val = 0; 1553 error = sysctl_handle_int(oidp, &val, 0, req); 1554 if (error != 0 || req->newptr == NULL) 1555 return (error); 1556 count = maxc = 0; 1557 st = spr = maxt = maxpr = 0; 1558 bzero(ccpbk, sizeof(ccpbk)); 1559 bzero(ct, sizeof(ct)); 1560 bzero(cpr, sizeof(cpr)); 1561 now = sbinuptime(); 1562 #ifdef SMP 1563 CPU_FOREACH(cpu) { 1564 cc = CC_CPU(cpu); 1565 #else 1566 cc = CC_CPU(timeout_cpu); 1567 #endif 1568 CC_LOCK(cc); 1569 for (i = 0; i < callwheelsize; i++) { 1570 sc = &cc->cc_callwheel[i]; 1571 c = 0; 1572 LIST_FOREACH(tmp, sc, c_links.le) { 1573 c++; 1574 t = tmp->c_time - now; 1575 if (t < 0) 1576 t = 0; 1577 st += t / SBT_1US; 1578 spr += tmp->c_precision / SBT_1US; 1579 if (t > maxt) 1580 maxt = t; 1581 if (tmp->c_precision > maxpr) 1582 maxpr = tmp->c_precision; 1583 ct[flssbt(t)]++; 1584 cpr[flssbt(tmp->c_precision)]++; 1585 } 1586 if (c > maxc) 1587 maxc = c; 1588 ccpbk[fls(c + c / 2)]++; 1589 count += c; 1590 } 1591 CC_UNLOCK(cc); 1592 #ifdef SMP 1593 } 1594 #endif 1595 1596 for (i = 0, tcum = 0; i < 64 && tcum < count / 2; i++) 1597 tcum += ct[i]; 1598 medt = (i >= 2) ? (((sbintime_t)1) << (i - 2)) : 0; 1599 for (i = 0, pcum = 0; i < 64 && pcum < count / 2; i++) 1600 pcum += cpr[i]; 1601 medpr = (i >= 2) ? (((sbintime_t)1) << (i - 2)) : 0; 1602 for (i = 0, c = 0; i < 32 && c < count / 2; i++) 1603 c += ccpbk[i]; 1604 medc = (i >= 2) ? (1 << (i - 2)) : 0; 1605 1606 printf("Scheduled callouts statistic snapshot:\n"); 1607 printf(" Callouts: %6d Buckets: %6d*%-3d Bucket size: 0.%06ds\n", 1608 count, callwheelsize, mp_ncpus, 1000000 >> CC_HASH_SHIFT); 1609 printf(" C/Bk: med %5d avg %6d.%06jd max %6d\n", 1610 medc, 1611 count / callwheelsize / mp_ncpus, 1612 (uint64_t)count * 1000000 / callwheelsize / mp_ncpus % 1000000, 1613 maxc); 1614 printf(" Time: med %5jd.%06jds avg %6jd.%06jds max %6jd.%06jds\n", 1615 medt / SBT_1S, (medt & 0xffffffff) * 1000000 >> 32, 1616 (st / count) / 1000000, (st / count) % 1000000, 1617 maxt / SBT_1S, (maxt & 0xffffffff) * 1000000 >> 32); 1618 printf(" Prec: med %5jd.%06jds avg %6jd.%06jds max %6jd.%06jds\n", 1619 medpr / SBT_1S, (medpr & 0xffffffff) * 1000000 >> 32, 1620 (spr / count) / 1000000, (spr / count) % 1000000, 1621 maxpr / SBT_1S, (maxpr & 0xffffffff) * 1000000 >> 32); 1622 printf(" Distribution: \tbuckets\t time\t tcum\t" 1623 " prec\t pcum\n"); 1624 for (i = 0, tcum = pcum = 0; i < 64; i++) { 1625 if (ct[i] == 0 && cpr[i] == 0) 1626 continue; 1627 t = (i != 0) ? (((sbintime_t)1) << (i - 1)) : 0; 1628 tcum += ct[i]; 1629 pcum += cpr[i]; 1630 printf(" %10jd.%06jds\t 2**%d\t%7d\t%7d\t%7d\t%7d\n", 1631 t / SBT_1S, (t & 0xffffffff) * 1000000 >> 32, 1632 i - 1 - (32 - CC_HASH_SHIFT), 1633 ct[i], tcum, cpr[i], pcum); 1634 } 1635 return (error); 1636 } 1637 SYSCTL_PROC(_kern, OID_AUTO, callout_stat, 1638 CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_MPSAFE, 1639 0, 0, sysctl_kern_callout_stat, "I", 1640 "Dump immediate statistic snapshot of the scheduled callouts"); 1641 1642 #ifdef DDB 1643 static void 1644 _show_callout(struct callout *c) 1645 { 1646 1647 db_printf("callout %p\n", c); 1648 #define C_DB_PRINTF(f, e) db_printf(" %s = " f "\n", #e, c->e); 1649 db_printf(" &c_links = %p\n", &(c->c_links)); 1650 C_DB_PRINTF("%" PRId64, c_time); 1651 C_DB_PRINTF("%" PRId64, c_precision); 1652 C_DB_PRINTF("%p", c_arg); 1653 C_DB_PRINTF("%p", c_func); 1654 C_DB_PRINTF("%p", c_lock); 1655 C_DB_PRINTF("%#x", c_flags); 1656 C_DB_PRINTF("%#x", c_iflags); 1657 C_DB_PRINTF("%d", c_cpu); 1658 #undef C_DB_PRINTF 1659 } 1660 1661 DB_SHOW_COMMAND(callout, db_show_callout) 1662 { 1663 1664 if (!have_addr) { 1665 db_printf("usage: show callout <struct callout *>\n"); 1666 return; 1667 } 1668 1669 _show_callout((struct callout *)addr); 1670 } 1671 #endif /* DDB */
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