1/*- 2 * Copyright (c) 2004 John Baldwin <jhb@FreeBSD.org> 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 24 * SUCH DAMAGE. 25 */ 26 27/* 28 * Implementation of sleep queues used to hold queue of threads blocked on 29 * a wait channel. Sleep queues are different from turnstiles in that wait 30 * channels are not owned by anyone, so there is no priority propagation. 31 * Sleep queues can also provide a timeout and can also be interrupted by 32 * signals. That said, there are several similarities between the turnstile 33 * and sleep queue implementations. (Note: turnstiles were implemented 34 * first.) For example, both use a hash table of the same size where each 35 * bucket is referred to as a "chain" that contains both a spin lock and 36 * a linked list of queues. An individual queue is located by using a hash 37 * to pick a chain, locking the chain, and then walking the chain searching 38 * for the queue. This means that a wait channel object does not need to 39 * embed its queue head just as locks do not embed their turnstile queue 40 * head. Threads also carry around a sleep queue that they lend to the 41 * wait channel when blocking. Just as in turnstiles, the queue includes 42 * a free list of the sleep queues of other threads blocked on the same 43 * wait channel in the case of multiple waiters. 44 * 45 * Some additional functionality provided by sleep queues include the 46 * ability to set a timeout. The timeout is managed using a per-thread 47 * callout that resumes a thread if it is asleep. A thread may also 48 * catch signals while it is asleep (aka an interruptible sleep). The 49 * signal code uses sleepq_abort() to interrupt a sleeping thread. Finally, 50 * sleep queues also provide some extra assertions. One is not allowed to 51 * mix the sleep/wakeup and cv APIs for a given wait channel. Also, one 52 * must consistently use the same lock to synchronize with a wait channel, 53 * though this check is currently only a warning for sleep/wakeup due to 54 * pre-existing abuse of that API. The same lock must also be held when 55 * awakening threads, though that is currently only enforced for condition 56 * variables. 57 */ 58 59#include <sys/cdefs.h> 60__FBSDID("$FreeBSD: stable/10/sys/kern/subr_sleepqueue.c 324800 2017-10-20 10:06:02Z hselasky $"); 61 62#include "opt_sleepqueue_profiling.h" 63#include "opt_ddb.h" 64#include "opt_kdtrace.h" 65#include "opt_sched.h" 66 67#include <sys/param.h> 68#include <sys/systm.h> 69#include <sys/lock.h> 70#include <sys/kernel.h> 71#include <sys/ktr.h> 72#include <sys/mutex.h> 73#include <sys/proc.h> 74#include <sys/sbuf.h> 75#include <sys/sched.h> 76#include <sys/sdt.h> 77#include <sys/signalvar.h> 78#include <sys/sleepqueue.h> 79#include <sys/sysctl.h> 80 81#include <vm/uma.h> 82 83#ifdef DDB 84#include <ddb/ddb.h> 85#endif 86 87/* 88 * Constants for the hash table of sleep queue chains. 89 * SC_TABLESIZE must be a power of two for SC_MASK to work properly. 90 */ 91#define SC_TABLESIZE 256 /* Must be power of 2. */ 92#define SC_MASK (SC_TABLESIZE - 1) 93#define SC_SHIFT 8 94#define SC_HASH(wc) ((((uintptr_t)(wc) >> SC_SHIFT) ^ (uintptr_t)(wc)) & \ 95 SC_MASK) 96#define SC_LOOKUP(wc) &sleepq_chains[SC_HASH(wc)] 97#define NR_SLEEPQS 2 98/* 99 * There are two different lists of sleep queues. Both lists are connected 100 * via the sq_hash entries. The first list is the sleep queue chain list 101 * that a sleep queue is on when it is attached to a wait channel. The 102 * second list is the free list hung off of a sleep queue that is attached 103 * to a wait channel. 104 * 105 * Each sleep queue also contains the wait channel it is attached to, the 106 * list of threads blocked on that wait channel, flags specific to the 107 * wait channel, and the lock used to synchronize with a wait channel. 108 * The flags are used to catch mismatches between the various consumers 109 * of the sleep queue API (e.g. sleep/wakeup and condition variables). 110 * The lock pointer is only used when invariants are enabled for various 111 * debugging checks. 112 * 113 * Locking key: 114 * c - sleep queue chain lock 115 */ 116struct sleepqueue { 117 TAILQ_HEAD(, thread) sq_blocked[NR_SLEEPQS]; /* (c) Blocked threads. */ 118 u_int sq_blockedcnt[NR_SLEEPQS]; /* (c) N. of blocked threads. */ 119 LIST_ENTRY(sleepqueue) sq_hash; /* (c) Chain and free list. */ 120 LIST_HEAD(, sleepqueue) sq_free; /* (c) Free queues. */ 121 void *sq_wchan; /* (c) Wait channel. */ 122 int sq_type; /* (c) Queue type. */ 123#ifdef INVARIANTS 124 struct lock_object *sq_lock; /* (c) Associated lock. */ 125#endif 126}; 127 128struct sleepqueue_chain { 129 LIST_HEAD(, sleepqueue) sc_queues; /* List of sleep queues. */ 130 struct mtx sc_lock; /* Spin lock for this chain. */ 131#ifdef SLEEPQUEUE_PROFILING 132 u_int sc_depth; /* Length of sc_queues. */ 133 u_int sc_max_depth; /* Max length of sc_queues. */ 134#endif 135}; 136 137#ifdef SLEEPQUEUE_PROFILING 138u_int sleepq_max_depth; 139static SYSCTL_NODE(_debug, OID_AUTO, sleepq, CTLFLAG_RD, 0, "sleepq profiling"); 140static SYSCTL_NODE(_debug_sleepq, OID_AUTO, chains, CTLFLAG_RD, 0, 141 "sleepq chain stats"); 142SYSCTL_UINT(_debug_sleepq, OID_AUTO, max_depth, CTLFLAG_RD, &sleepq_max_depth, 143 0, "maxmimum depth achieved of a single chain"); 144 145static void sleepq_profile(const char *wmesg); 146static int prof_enabled; 147#endif 148static struct sleepqueue_chain sleepq_chains[SC_TABLESIZE]; 149static uma_zone_t sleepq_zone; 150 151/* 152 * Prototypes for non-exported routines. 153 */ 154static int sleepq_catch_signals(void *wchan, int pri); 155static int sleepq_check_signals(void); 156static int sleepq_check_timeout(void); 157#ifdef INVARIANTS 158static void sleepq_dtor(void *mem, int size, void *arg); 159#endif 160static int sleepq_init(void *mem, int size, int flags); 161static int sleepq_resume_thread(struct sleepqueue *sq, struct thread *td, 162 int pri); 163static void sleepq_switch(void *wchan, int pri); 164static void sleepq_timeout(void *arg); 165 166SDT_PROBE_DECLARE(sched, , , sleep); 167SDT_PROBE_DECLARE(sched, , , wakeup); 168 169/* 170 * Early initialization of sleep queues that is called from the sleepinit() 171 * SYSINIT. 172 */ 173void 174init_sleepqueues(void) 175{ 176#ifdef SLEEPQUEUE_PROFILING 177 struct sysctl_oid *chain_oid; 178 char chain_name[10]; 179#endif 180 int i; 181 182 for (i = 0; i < SC_TABLESIZE; i++) { 183 LIST_INIT(&sleepq_chains[i].sc_queues); 184 mtx_init(&sleepq_chains[i].sc_lock, "sleepq chain", NULL, 185 MTX_SPIN | MTX_RECURSE); 186#ifdef SLEEPQUEUE_PROFILING 187 snprintf(chain_name, sizeof(chain_name), "%d", i); 188 chain_oid = SYSCTL_ADD_NODE(NULL, 189 SYSCTL_STATIC_CHILDREN(_debug_sleepq_chains), OID_AUTO, 190 chain_name, CTLFLAG_RD, NULL, "sleepq chain stats"); 191 SYSCTL_ADD_UINT(NULL, SYSCTL_CHILDREN(chain_oid), OID_AUTO, 192 "depth", CTLFLAG_RD, &sleepq_chains[i].sc_depth, 0, NULL); 193 SYSCTL_ADD_UINT(NULL, SYSCTL_CHILDREN(chain_oid), OID_AUTO, 194 "max_depth", CTLFLAG_RD, &sleepq_chains[i].sc_max_depth, 0, 195 NULL); 196#endif 197 } 198 sleepq_zone = uma_zcreate("SLEEPQUEUE", sizeof(struct sleepqueue), 199#ifdef INVARIANTS 200 NULL, sleepq_dtor, sleepq_init, NULL, UMA_ALIGN_CACHE, 0); 201#else 202 NULL, NULL, sleepq_init, NULL, UMA_ALIGN_CACHE, 0); 203#endif 204 205 thread0.td_sleepqueue = sleepq_alloc(); 206} 207 208/* 209 * Get a sleep queue for a new thread. 210 */ 211struct sleepqueue * 212sleepq_alloc(void) 213{ 214 215 return (uma_zalloc(sleepq_zone, M_WAITOK)); 216} 217 218/* 219 * Free a sleep queue when a thread is destroyed. 220 */ 221void 222sleepq_free(struct sleepqueue *sq) 223{ 224 225 uma_zfree(sleepq_zone, sq); 226} 227 228/* 229 * Lock the sleep queue chain associated with the specified wait channel. 230 */ 231void 232sleepq_lock(void *wchan) 233{ 234 struct sleepqueue_chain *sc; 235 236 sc = SC_LOOKUP(wchan); 237 mtx_lock_spin(&sc->sc_lock); 238} 239 240/* 241 * Look up the sleep queue associated with a given wait channel in the hash 242 * table locking the associated sleep queue chain. If no queue is found in 243 * the table, NULL is returned. 244 */ 245struct sleepqueue * 246sleepq_lookup(void *wchan) 247{ 248 struct sleepqueue_chain *sc; 249 struct sleepqueue *sq; 250 251 KASSERT(wchan != NULL, ("%s: invalid NULL wait channel", __func__)); 252 sc = SC_LOOKUP(wchan); 253 mtx_assert(&sc->sc_lock, MA_OWNED); 254 LIST_FOREACH(sq, &sc->sc_queues, sq_hash) 255 if (sq->sq_wchan == wchan) 256 return (sq); 257 return (NULL); 258} 259 260/* 261 * Unlock the sleep queue chain associated with a given wait channel. 262 */ 263void 264sleepq_release(void *wchan) 265{ 266 struct sleepqueue_chain *sc; 267 268 sc = SC_LOOKUP(wchan); 269 mtx_unlock_spin(&sc->sc_lock); 270} 271 272/* 273 * Places the current thread on the sleep queue for the specified wait 274 * channel. If INVARIANTS is enabled, then it associates the passed in 275 * lock with the sleepq to make sure it is held when that sleep queue is 276 * woken up. 277 */ 278void 279sleepq_add(void *wchan, struct lock_object *lock, const char *wmesg, int flags, 280 int queue) 281{ 282 struct sleepqueue_chain *sc; 283 struct sleepqueue *sq; 284 struct thread *td; 285 286 td = curthread; 287 sc = SC_LOOKUP(wchan); 288 mtx_assert(&sc->sc_lock, MA_OWNED); 289 MPASS(td->td_sleepqueue != NULL); 290 MPASS(wchan != NULL); 291 MPASS((queue >= 0) && (queue < NR_SLEEPQS)); 292 293 /* If this thread is not allowed to sleep, die a horrible death. */ 294 KASSERT(td->td_no_sleeping == 0, 295 ("%s: td %p to sleep on wchan %p with sleeping prohibited", 296 __func__, td, wchan)); 297 298 /* Look up the sleep queue associated with the wait channel 'wchan'. */ 299 sq = sleepq_lookup(wchan); 300 301 /* 302 * If the wait channel does not already have a sleep queue, use 303 * this thread's sleep queue. Otherwise, insert the current thread 304 * into the sleep queue already in use by this wait channel. 305 */ 306 if (sq == NULL) { 307#ifdef INVARIANTS 308 int i; 309 310 sq = td->td_sleepqueue; 311 for (i = 0; i < NR_SLEEPQS; i++) { 312 KASSERT(TAILQ_EMPTY(&sq->sq_blocked[i]), 313 ("thread's sleep queue %d is not empty", i)); 314 KASSERT(sq->sq_blockedcnt[i] == 0, 315 ("thread's sleep queue %d count mismatches", i)); 316 } 317 KASSERT(LIST_EMPTY(&sq->sq_free), 318 ("thread's sleep queue has a non-empty free list")); 319 KASSERT(sq->sq_wchan == NULL, ("stale sq_wchan pointer")); 320 sq->sq_lock = lock; 321#endif 322#ifdef SLEEPQUEUE_PROFILING 323 sc->sc_depth++; 324 if (sc->sc_depth > sc->sc_max_depth) { 325 sc->sc_max_depth = sc->sc_depth; 326 if (sc->sc_max_depth > sleepq_max_depth) 327 sleepq_max_depth = sc->sc_max_depth; 328 } 329#endif 330 sq = td->td_sleepqueue; 331 LIST_INSERT_HEAD(&sc->sc_queues, sq, sq_hash); 332 sq->sq_wchan = wchan; 333 sq->sq_type = flags & SLEEPQ_TYPE; 334 } else { 335 MPASS(wchan == sq->sq_wchan); 336 MPASS(lock == sq->sq_lock); 337 MPASS((flags & SLEEPQ_TYPE) == sq->sq_type); 338 LIST_INSERT_HEAD(&sq->sq_free, td->td_sleepqueue, sq_hash); 339 } 340 thread_lock(td); 341 TAILQ_INSERT_TAIL(&sq->sq_blocked[queue], td, td_slpq); 342 sq->sq_blockedcnt[queue]++; 343 td->td_sleepqueue = NULL; 344 td->td_sqqueue = queue; 345 td->td_wchan = wchan; 346 td->td_wmesg = wmesg; 347 if (flags & SLEEPQ_INTERRUPTIBLE) { 348 td->td_flags |= TDF_SINTR; 349 td->td_flags &= ~TDF_SLEEPABORT; 350 } 351 thread_unlock(td); 352} 353 354/* 355 * Sets a timeout that will remove the current thread from the specified 356 * sleep queue after timo ticks if the thread has not already been awakened. 357 */ 358void 359sleepq_set_timeout_sbt(void *wchan, sbintime_t sbt, sbintime_t pr, 360 int flags) 361{ 362 struct sleepqueue_chain *sc; 363 struct thread *td; 364 sbintime_t pr1; 365 366 td = curthread; 367 sc = SC_LOOKUP(wchan); 368 mtx_assert(&sc->sc_lock, MA_OWNED); 369 MPASS(TD_ON_SLEEPQ(td)); 370 MPASS(td->td_sleepqueue == NULL); 371 MPASS(wchan != NULL); 372 KASSERT(td->td_sleeptimo == 0, ("td %d %p td_sleeptimo %jx", 373 td->td_tid, td, (uintmax_t)td->td_sleeptimo)); 374 thread_lock(td); 375 callout_when(sbt, pr, flags, &td->td_sleeptimo, &pr1); 376 thread_unlock(td); 377 callout_reset_sbt_on(&td->td_slpcallout, td->td_sleeptimo, pr1, 378 sleepq_timeout, td, PCPU_GET(cpuid), flags | C_PRECALC | 379 C_DIRECT_EXEC); 380} 381 382/* 383 * Return the number of actual sleepers for the specified queue. 384 */ 385u_int 386sleepq_sleepcnt(void *wchan, int queue) 387{ 388 struct sleepqueue *sq; 389 390 KASSERT(wchan != NULL, ("%s: invalid NULL wait channel", __func__)); 391 MPASS((queue >= 0) && (queue < NR_SLEEPQS)); 392 sq = sleepq_lookup(wchan); 393 if (sq == NULL) 394 return (0); 395 return (sq->sq_blockedcnt[queue]); 396} 397 398/* 399 * Marks the pending sleep of the current thread as interruptible and 400 * makes an initial check for pending signals before putting a thread 401 * to sleep. Enters and exits with the thread lock held. Thread lock 402 * may have transitioned from the sleepq lock to a run lock. 403 */ 404static int 405sleepq_catch_signals(void *wchan, int pri) 406{ 407 struct sleepqueue_chain *sc; 408 struct sleepqueue *sq; 409 struct thread *td; 410 struct proc *p; 411 struct sigacts *ps; 412 int sig, ret; 413 414 ret = 0; 415 td = curthread; 416 p = curproc; 417 sc = SC_LOOKUP(wchan); 418 mtx_assert(&sc->sc_lock, MA_OWNED); 419 MPASS(wchan != NULL); 420 if ((td->td_pflags & TDP_WAKEUP) != 0) { 421 td->td_pflags &= ~TDP_WAKEUP; 422 ret = EINTR; 423 thread_lock(td); 424 goto out; 425 } 426 427 /* 428 * See if there are any pending signals or suspension requests for this 429 * thread. If not, we can switch immediately. 430 */ 431 thread_lock(td); 432 if ((td->td_flags & (TDF_NEEDSIGCHK | TDF_NEEDSUSPCHK)) != 0) { 433 thread_unlock(td); 434 mtx_unlock_spin(&sc->sc_lock); 435 CTR3(KTR_PROC, "sleepq catching signals: thread %p (pid %ld, %s)", 436 (void *)td, (long)p->p_pid, td->td_name); 437 PROC_LOCK(p); 438 /* 439 * Check for suspension first. Checking for signals and then 440 * suspending could result in a missed signal, since a signal 441 * can be delivered while this thread is suspended. 442 */ 443 if ((td->td_flags & TDF_NEEDSUSPCHK) != 0) { 444 ret = thread_suspend_check(1); 445 MPASS(ret == 0 || ret == EINTR || ret == ERESTART); 446 if (ret != 0) { 447 PROC_UNLOCK(p); 448 mtx_lock_spin(&sc->sc_lock); 449 thread_lock(td); 450 goto out; 451 } 452 } 453 if ((td->td_flags & TDF_NEEDSIGCHK) != 0) { 454 ps = p->p_sigacts; 455 mtx_lock(&ps->ps_mtx); 456 sig = cursig(td); 457 if (sig != 0) 458 ret = SIGISMEMBER(ps->ps_sigintr, sig) ? 459 EINTR : ERESTART; 460 mtx_unlock(&ps->ps_mtx); 461 } 462 /* 463 * Lock the per-process spinlock prior to dropping the PROC_LOCK 464 * to avoid a signal delivery race. PROC_LOCK, PROC_SLOCK, and 465 * thread_lock() are currently held in tdsendsignal(). 466 */ 467 PROC_SLOCK(p); 468 mtx_lock_spin(&sc->sc_lock); 469 PROC_UNLOCK(p); 470 thread_lock(td); 471 PROC_SUNLOCK(p); 472 } 473 if (ret == 0) { 474 sleepq_switch(wchan, pri); 475 return (0); 476 } 477out: 478 /* 479 * There were pending signals and this thread is still 480 * on the sleep queue, remove it from the sleep queue. 481 */ 482 if (TD_ON_SLEEPQ(td)) { 483 sq = sleepq_lookup(wchan); 484 if (sleepq_resume_thread(sq, td, 0)) { 485#ifdef INVARIANTS 486 /* 487 * This thread hasn't gone to sleep yet, so it 488 * should not be swapped out. 489 */ 490 panic("not waking up swapper"); 491#endif 492 } 493 } 494 mtx_unlock_spin(&sc->sc_lock); 495 MPASS(td->td_lock != &sc->sc_lock); 496 return (ret); 497} 498 499/* 500 * Switches to another thread if we are still asleep on a sleep queue. 501 * Returns with thread lock. 502 */ 503static void 504sleepq_switch(void *wchan, int pri) 505{ 506 struct sleepqueue_chain *sc; 507 struct sleepqueue *sq; 508 struct thread *td; 509 510 td = curthread; 511 sc = SC_LOOKUP(wchan); 512 mtx_assert(&sc->sc_lock, MA_OWNED); 513 THREAD_LOCK_ASSERT(td, MA_OWNED); 514 515 /* 516 * If we have a sleep queue, then we've already been woken up, so 517 * just return. 518 */ 519 if (td->td_sleepqueue != NULL) { 520 mtx_unlock_spin(&sc->sc_lock); 521 return; 522 } 523 524 /* 525 * If TDF_TIMEOUT is set, then our sleep has been timed out 526 * already but we are still on the sleep queue, so dequeue the 527 * thread and return. 528 */ 529 if (td->td_flags & TDF_TIMEOUT) { 530 MPASS(TD_ON_SLEEPQ(td)); 531 sq = sleepq_lookup(wchan); 532 if (sleepq_resume_thread(sq, td, 0)) { 533#ifdef INVARIANTS 534 /* 535 * This thread hasn't gone to sleep yet, so it 536 * should not be swapped out. 537 */ 538 panic("not waking up swapper"); 539#endif 540 } 541 mtx_unlock_spin(&sc->sc_lock); 542 return; 543 } 544#ifdef SLEEPQUEUE_PROFILING 545 if (prof_enabled) 546 sleepq_profile(td->td_wmesg); 547#endif 548 MPASS(td->td_sleepqueue == NULL); 549 sched_sleep(td, pri); 550 thread_lock_set(td, &sc->sc_lock); 551 SDT_PROBE0(sched, , , sleep); 552 TD_SET_SLEEPING(td); 553 mi_switch(SW_VOL | SWT_SLEEPQ, NULL); 554 KASSERT(TD_IS_RUNNING(td), ("running but not TDS_RUNNING")); 555 CTR3(KTR_PROC, "sleepq resume: thread %p (pid %ld, %s)", 556 (void *)td, (long)td->td_proc->p_pid, (void *)td->td_name); 557} 558 559/* 560 * Check to see if we timed out. 561 */ 562static int 563sleepq_check_timeout(void) 564{ 565 struct thread *td; 566 int res; 567 568 td = curthread; 569 THREAD_LOCK_ASSERT(td, MA_OWNED); 570 571 /* 572 * If TDF_TIMEOUT is set, we timed out. But recheck 573 * td_sleeptimo anyway. 574 */ 575 res = 0; 576 if (td->td_sleeptimo != 0) { 577 if (td->td_sleeptimo <= sbinuptime()) 578 res = EWOULDBLOCK; 579 td->td_sleeptimo = 0; 580 } 581 if (td->td_flags & TDF_TIMEOUT) 582 td->td_flags &= ~TDF_TIMEOUT; 583 else 584 /* 585 * We ignore the situation where timeout subsystem was 586 * unable to stop our callout. The struct thread is 587 * type-stable, the callout will use the correct 588 * memory when running. The checks of the 589 * td_sleeptimo value in this function and in 590 * sleepq_timeout() ensure that the thread does not 591 * get spurious wakeups, even if the callout was reset 592 * or thread reused. 593 */ 594 callout_stop(&td->td_slpcallout); 595 return (res); 596} 597 598/* 599 * Check to see if we were awoken by a signal. 600 */ 601static int 602sleepq_check_signals(void) 603{ 604 struct thread *td; 605 606 td = curthread; 607 THREAD_LOCK_ASSERT(td, MA_OWNED); 608 609 /* We are no longer in an interruptible sleep. */ 610 if (td->td_flags & TDF_SINTR) 611 td->td_flags &= ~TDF_SINTR; 612 613 if (td->td_flags & TDF_SLEEPABORT) { 614 td->td_flags &= ~TDF_SLEEPABORT; 615 return (td->td_intrval); 616 } 617 618 return (0); 619} 620 621/* 622 * Block the current thread until it is awakened from its sleep queue. 623 */ 624void 625sleepq_wait(void *wchan, int pri) 626{ 627 struct thread *td; 628 629 td = curthread; 630 MPASS(!(td->td_flags & TDF_SINTR)); 631 thread_lock(td); 632 sleepq_switch(wchan, pri); 633 thread_unlock(td); 634} 635 636/* 637 * Block the current thread until it is awakened from its sleep queue 638 * or it is interrupted by a signal. 639 */ 640int 641sleepq_wait_sig(void *wchan, int pri) 642{ 643 int rcatch; 644 int rval; 645 646 rcatch = sleepq_catch_signals(wchan, pri); 647 rval = sleepq_check_signals(); 648 thread_unlock(curthread); 649 if (rcatch) 650 return (rcatch); 651 return (rval); 652} 653 654/* 655 * Block the current thread until it is awakened from its sleep queue 656 * or it times out while waiting. 657 */ 658int 659sleepq_timedwait(void *wchan, int pri) 660{ 661 struct thread *td; 662 int rval; 663 664 td = curthread; 665 MPASS(!(td->td_flags & TDF_SINTR)); 666 thread_lock(td); 667 sleepq_switch(wchan, pri); 668 rval = sleepq_check_timeout(); 669 thread_unlock(td); 670 671 return (rval); 672} 673 674/* 675 * Block the current thread until it is awakened from its sleep queue, 676 * it is interrupted by a signal, or it times out waiting to be awakened. 677 */ 678int 679sleepq_timedwait_sig(void *wchan, int pri) 680{ 681 int rcatch, rvalt, rvals; 682 683 rcatch = sleepq_catch_signals(wchan, pri); 684 rvalt = sleepq_check_timeout(); 685 rvals = sleepq_check_signals(); 686 thread_unlock(curthread); 687 if (rcatch) 688 return (rcatch); 689 if (rvals) 690 return (rvals); 691 return (rvalt); 692} 693 694/* 695 * Returns the type of sleepqueue given a waitchannel. 696 */ 697int 698sleepq_type(void *wchan) 699{ 700 struct sleepqueue *sq; 701 int type; 702 703 MPASS(wchan != NULL); 704 705 sleepq_lock(wchan); 706 sq = sleepq_lookup(wchan); 707 if (sq == NULL) { 708 sleepq_release(wchan); 709 return (-1); 710 } 711 type = sq->sq_type; 712 sleepq_release(wchan); 713 return (type); 714} 715 716/* 717 * Removes a thread from a sleep queue and makes it 718 * runnable. 719 */ 720static int 721sleepq_resume_thread(struct sleepqueue *sq, struct thread *td, int pri) 722{ 723 struct sleepqueue_chain *sc; 724 725 MPASS(td != NULL); 726 MPASS(sq->sq_wchan != NULL); 727 MPASS(td->td_wchan == sq->sq_wchan); 728 MPASS(td->td_sqqueue < NR_SLEEPQS && td->td_sqqueue >= 0); 729 THREAD_LOCK_ASSERT(td, MA_OWNED); 730 sc = SC_LOOKUP(sq->sq_wchan); 731 mtx_assert(&sc->sc_lock, MA_OWNED); 732 733 SDT_PROBE2(sched, , , wakeup, td, td->td_proc); 734 735 /* Remove the thread from the queue. */ 736 sq->sq_blockedcnt[td->td_sqqueue]--; 737 TAILQ_REMOVE(&sq->sq_blocked[td->td_sqqueue], td, td_slpq); 738 739 /* 740 * Get a sleep queue for this thread. If this is the last waiter, 741 * use the queue itself and take it out of the chain, otherwise, 742 * remove a queue from the free list. 743 */ 744 if (LIST_EMPTY(&sq->sq_free)) { 745 td->td_sleepqueue = sq; 746#ifdef INVARIANTS 747 sq->sq_wchan = NULL; 748#endif 749#ifdef SLEEPQUEUE_PROFILING 750 sc->sc_depth--; 751#endif 752 } else 753 td->td_sleepqueue = LIST_FIRST(&sq->sq_free); 754 LIST_REMOVE(td->td_sleepqueue, sq_hash); 755 756 td->td_wmesg = NULL; 757 td->td_wchan = NULL; 758 td->td_flags &= ~TDF_SINTR; 759 760 CTR3(KTR_PROC, "sleepq_wakeup: thread %p (pid %ld, %s)", 761 (void *)td, (long)td->td_proc->p_pid, td->td_name); 762 763 /* Adjust priority if requested. */ 764 MPASS(pri == 0 || (pri >= PRI_MIN && pri <= PRI_MAX)); 765 if (pri != 0 && td->td_priority > pri && 766 PRI_BASE(td->td_pri_class) == PRI_TIMESHARE) 767 sched_prio(td, pri); 768 769 /* 770 * Note that thread td might not be sleeping if it is running 771 * sleepq_catch_signals() on another CPU or is blocked on its 772 * proc lock to check signals. There's no need to mark the 773 * thread runnable in that case. 774 */ 775 if (TD_IS_SLEEPING(td)) { 776 TD_CLR_SLEEPING(td); 777 return (setrunnable(td)); 778 } 779 return (0); 780} 781 782#ifdef INVARIANTS 783/* 784 * UMA zone item deallocator. 785 */ 786static void 787sleepq_dtor(void *mem, int size, void *arg) 788{ 789 struct sleepqueue *sq; 790 int i; 791 792 sq = mem; 793 for (i = 0; i < NR_SLEEPQS; i++) { 794 MPASS(TAILQ_EMPTY(&sq->sq_blocked[i])); 795 MPASS(sq->sq_blockedcnt[i] == 0); 796 } 797} 798#endif 799 800/* 801 * UMA zone item initializer. 802 */ 803static int 804sleepq_init(void *mem, int size, int flags) 805{ 806 struct sleepqueue *sq; 807 int i; 808 809 bzero(mem, size); 810 sq = mem; 811 for (i = 0; i < NR_SLEEPQS; i++) { 812 TAILQ_INIT(&sq->sq_blocked[i]); 813 sq->sq_blockedcnt[i] = 0; 814 } 815 LIST_INIT(&sq->sq_free); 816 return (0); 817} 818 819/* 820 * Find the highest priority thread sleeping on a wait channel and resume it. 821 */ 822int 823sleepq_signal(void *wchan, int flags, int pri, int queue) 824{ 825 struct sleepqueue *sq; 826 struct thread *td, *besttd; 827 int wakeup_swapper; 828 829 CTR2(KTR_PROC, "sleepq_signal(%p, %d)", wchan, flags); 830 KASSERT(wchan != NULL, ("%s: invalid NULL wait channel", __func__)); 831 MPASS((queue >= 0) && (queue < NR_SLEEPQS)); 832 sq = sleepq_lookup(wchan); 833 if (sq == NULL) 834 return (0); 835 KASSERT(sq->sq_type == (flags & SLEEPQ_TYPE), 836 ("%s: mismatch between sleep/wakeup and cv_*", __func__)); 837 838 /* 839 * Find the highest priority thread on the queue. If there is a 840 * tie, use the thread that first appears in the queue as it has 841 * been sleeping the longest since threads are always added to 842 * the tail of sleep queues. 843 */ 844 besttd = NULL; 845 TAILQ_FOREACH(td, &sq->sq_blocked[queue], td_slpq) { 846 if (besttd == NULL || td->td_priority < besttd->td_priority) 847 besttd = td; 848 } 849 MPASS(besttd != NULL); 850 thread_lock(besttd); 851 wakeup_swapper = sleepq_resume_thread(sq, besttd, pri); 852 thread_unlock(besttd); 853 return (wakeup_swapper); 854} 855 856/* 857 * Resume all threads sleeping on a specified wait channel. 858 */ 859int 860sleepq_broadcast(void *wchan, int flags, int pri, int queue) 861{ 862 struct sleepqueue *sq; 863 struct thread *td, *tdn; 864 int wakeup_swapper; 865 866 CTR2(KTR_PROC, "sleepq_broadcast(%p, %d)", wchan, flags); 867 KASSERT(wchan != NULL, ("%s: invalid NULL wait channel", __func__)); 868 MPASS((queue >= 0) && (queue < NR_SLEEPQS)); 869 sq = sleepq_lookup(wchan); 870 if (sq == NULL) 871 return (0); 872 KASSERT(sq->sq_type == (flags & SLEEPQ_TYPE), 873 ("%s: mismatch between sleep/wakeup and cv_*", __func__)); 874 875 /* Resume all blocked threads on the sleep queue. */ 876 wakeup_swapper = 0; 877 TAILQ_FOREACH_SAFE(td, &sq->sq_blocked[queue], td_slpq, tdn) { 878 thread_lock(td); 879 if (sleepq_resume_thread(sq, td, pri)) 880 wakeup_swapper = 1; 881 thread_unlock(td); 882 } 883 return (wakeup_swapper); 884} 885 886/* 887 * Time sleeping threads out. When the timeout expires, the thread is 888 * removed from the sleep queue and made runnable if it is still asleep. 889 */ 890static void 891sleepq_timeout(void *arg) 892{ 893 struct sleepqueue_chain *sc; 894 struct sleepqueue *sq; 895 struct thread *td; 896 void *wchan; 897 int wakeup_swapper; 898 899 td = arg; 900 wakeup_swapper = 0; 901 CTR3(KTR_PROC, "sleepq_timeout: thread %p (pid %ld, %s)", 902 (void *)td, (long)td->td_proc->p_pid, (void *)td->td_name); 903 904 thread_lock(td); 905 906 if (td->td_sleeptimo > sbinuptime() || td->td_sleeptimo == 0) { 907 /* 908 * The thread does not want a timeout (yet). 909 */ 910 } else if (TD_IS_SLEEPING(td) && TD_ON_SLEEPQ(td)) { 911 /* 912 * See if the thread is asleep and get the wait 913 * channel if it is. 914 */ 915 wchan = td->td_wchan; 916 sc = SC_LOOKUP(wchan); 917 THREAD_LOCKPTR_ASSERT(td, &sc->sc_lock); 918 sq = sleepq_lookup(wchan); 919 MPASS(sq != NULL); 920 td->td_flags |= TDF_TIMEOUT; 921 wakeup_swapper = sleepq_resume_thread(sq, td, 0); 922 } else if (TD_ON_SLEEPQ(td)) { 923 /* 924 * If the thread is on the SLEEPQ but isn't sleeping 925 * yet, it can either be on another CPU in between 926 * sleepq_add() and one of the sleepq_*wait*() 927 * routines or it can be in sleepq_catch_signals(). 928 */ 929 td->td_flags |= TDF_TIMEOUT; 930 } 931 932 thread_unlock(td); 933 if (wakeup_swapper) 934 kick_proc0(); 935} 936 937/* 938 * Resumes a specific thread from the sleep queue associated with a specific 939 * wait channel if it is on that queue. 940 */ 941void 942sleepq_remove(struct thread *td, void *wchan) 943{ 944 struct sleepqueue *sq; 945 int wakeup_swapper; 946 947 /* 948 * Look up the sleep queue for this wait channel, then re-check 949 * that the thread is asleep on that channel, if it is not, then 950 * bail. 951 */ 952 MPASS(wchan != NULL); 953 sleepq_lock(wchan); 954 sq = sleepq_lookup(wchan); 955 /* 956 * We can not lock the thread here as it may be sleeping on a 957 * different sleepq. However, holding the sleepq lock for this 958 * wchan can guarantee that we do not miss a wakeup for this 959 * channel. The asserts below will catch any false positives. 960 */ 961 if (!TD_ON_SLEEPQ(td) || td->td_wchan != wchan) { 962 sleepq_release(wchan); 963 return; 964 } 965 /* Thread is asleep on sleep queue sq, so wake it up. */ 966 thread_lock(td); 967 MPASS(sq != NULL); 968 MPASS(td->td_wchan == wchan); 969 wakeup_swapper = sleepq_resume_thread(sq, td, 0); 970 thread_unlock(td); 971 sleepq_release(wchan); 972 if (wakeup_swapper) 973 kick_proc0(); 974} 975 976/* 977 * Abort a thread as if an interrupt had occurred. Only abort 978 * interruptible waits (unfortunately it isn't safe to abort others). 979 */ 980int 981sleepq_abort(struct thread *td, int intrval) 982{ 983 struct sleepqueue *sq; 984 void *wchan; 985 986 THREAD_LOCK_ASSERT(td, MA_OWNED); 987 MPASS(TD_ON_SLEEPQ(td)); 988 MPASS(td->td_flags & TDF_SINTR); 989 MPASS(intrval == EINTR || intrval == ERESTART); 990 991 /* 992 * If the TDF_TIMEOUT flag is set, just leave. A 993 * timeout is scheduled anyhow. 994 */ 995 if (td->td_flags & TDF_TIMEOUT) 996 return (0); 997 998 CTR3(KTR_PROC, "sleepq_abort: thread %p (pid %ld, %s)", 999 (void *)td, (long)td->td_proc->p_pid, (void *)td->td_name); 1000 td->td_intrval = intrval; 1001 td->td_flags |= TDF_SLEEPABORT; 1002 /* 1003 * If the thread has not slept yet it will find the signal in 1004 * sleepq_catch_signals() and call sleepq_resume_thread. Otherwise 1005 * we have to do it here. 1006 */ 1007 if (!TD_IS_SLEEPING(td)) 1008 return (0); 1009 wchan = td->td_wchan; 1010 MPASS(wchan != NULL); 1011 sq = sleepq_lookup(wchan); 1012 MPASS(sq != NULL); 1013 1014 /* Thread is asleep on sleep queue sq, so wake it up. */ 1015 return (sleepq_resume_thread(sq, td, 0)); 1016} 1017 1018#ifdef SLEEPQUEUE_PROFILING 1019#define SLEEPQ_PROF_LOCATIONS 1024 1020#define SLEEPQ_SBUFSIZE 512 1021struct sleepq_prof { 1022 LIST_ENTRY(sleepq_prof) sp_link; 1023 const char *sp_wmesg; 1024 long sp_count; 1025}; 1026 1027LIST_HEAD(sqphead, sleepq_prof); 1028 1029struct sqphead sleepq_prof_free; 1030struct sqphead sleepq_hash[SC_TABLESIZE]; 1031static struct sleepq_prof sleepq_profent[SLEEPQ_PROF_LOCATIONS]; 1032static struct mtx sleepq_prof_lock; 1033MTX_SYSINIT(sleepq_prof_lock, &sleepq_prof_lock, "sleepq_prof", MTX_SPIN); 1034 1035static void 1036sleepq_profile(const char *wmesg) 1037{ 1038 struct sleepq_prof *sp; 1039 1040 mtx_lock_spin(&sleepq_prof_lock); 1041 if (prof_enabled == 0) 1042 goto unlock; 1043 LIST_FOREACH(sp, &sleepq_hash[SC_HASH(wmesg)], sp_link) 1044 if (sp->sp_wmesg == wmesg) 1045 goto done; 1046 sp = LIST_FIRST(&sleepq_prof_free); 1047 if (sp == NULL) 1048 goto unlock; 1049 sp->sp_wmesg = wmesg; 1050 LIST_REMOVE(sp, sp_link); 1051 LIST_INSERT_HEAD(&sleepq_hash[SC_HASH(wmesg)], sp, sp_link); 1052done: 1053 sp->sp_count++; 1054unlock: 1055 mtx_unlock_spin(&sleepq_prof_lock); 1056 return; 1057} 1058 1059static void 1060sleepq_prof_reset(void) 1061{ 1062 struct sleepq_prof *sp; 1063 int enabled; 1064 int i; 1065 1066 mtx_lock_spin(&sleepq_prof_lock); 1067 enabled = prof_enabled; 1068 prof_enabled = 0; 1069 for (i = 0; i < SC_TABLESIZE; i++) 1070 LIST_INIT(&sleepq_hash[i]); 1071 LIST_INIT(&sleepq_prof_free); 1072 for (i = 0; i < SLEEPQ_PROF_LOCATIONS; i++) { 1073 sp = &sleepq_profent[i]; 1074 sp->sp_wmesg = NULL; 1075 sp->sp_count = 0; 1076 LIST_INSERT_HEAD(&sleepq_prof_free, sp, sp_link); 1077 } 1078 prof_enabled = enabled; 1079 mtx_unlock_spin(&sleepq_prof_lock); 1080} 1081 1082static int 1083enable_sleepq_prof(SYSCTL_HANDLER_ARGS) 1084{ 1085 int error, v; 1086 1087 v = prof_enabled; 1088 error = sysctl_handle_int(oidp, &v, v, req); 1089 if (error) 1090 return (error); 1091 if (req->newptr == NULL) 1092 return (error); 1093 if (v == prof_enabled) 1094 return (0); 1095 if (v == 1) 1096 sleepq_prof_reset(); 1097 mtx_lock_spin(&sleepq_prof_lock); 1098 prof_enabled = !!v; 1099 mtx_unlock_spin(&sleepq_prof_lock); 1100 1101 return (0); 1102} 1103 1104static int 1105reset_sleepq_prof_stats(SYSCTL_HANDLER_ARGS) 1106{ 1107 int error, v; 1108 1109 v = 0; 1110 error = sysctl_handle_int(oidp, &v, 0, req); 1111 if (error) 1112 return (error); 1113 if (req->newptr == NULL) 1114 return (error); 1115 if (v == 0) 1116 return (0); 1117 sleepq_prof_reset(); 1118 1119 return (0); 1120} 1121 1122static int 1123dump_sleepq_prof_stats(SYSCTL_HANDLER_ARGS) 1124{ 1125 struct sleepq_prof *sp; 1126 struct sbuf *sb; 1127 int enabled; 1128 int error; 1129 int i; 1130 1131 error = sysctl_wire_old_buffer(req, 0); 1132 if (error != 0) 1133 return (error); 1134 sb = sbuf_new_for_sysctl(NULL, NULL, SLEEPQ_SBUFSIZE, req); 1135 sbuf_printf(sb, "\nwmesg\tcount\n"); 1136 enabled = prof_enabled; 1137 mtx_lock_spin(&sleepq_prof_lock); 1138 prof_enabled = 0; 1139 mtx_unlock_spin(&sleepq_prof_lock); 1140 for (i = 0; i < SC_TABLESIZE; i++) { 1141 LIST_FOREACH(sp, &sleepq_hash[i], sp_link) { 1142 sbuf_printf(sb, "%s\t%ld\n", 1143 sp->sp_wmesg, sp->sp_count); 1144 } 1145 } 1146 mtx_lock_spin(&sleepq_prof_lock); 1147 prof_enabled = enabled; 1148 mtx_unlock_spin(&sleepq_prof_lock); 1149 1150 error = sbuf_finish(sb); 1151 sbuf_delete(sb); 1152 return (error); 1153} 1154 1155SYSCTL_PROC(_debug_sleepq, OID_AUTO, stats, CTLTYPE_STRING | CTLFLAG_RD, 1156 NULL, 0, dump_sleepq_prof_stats, "A", "Sleepqueue profiling statistics"); 1157SYSCTL_PROC(_debug_sleepq, OID_AUTO, reset, CTLTYPE_INT | CTLFLAG_RW, 1158 NULL, 0, reset_sleepq_prof_stats, "I", 1159 "Reset sleepqueue profiling statistics"); 1160SYSCTL_PROC(_debug_sleepq, OID_AUTO, enable, CTLTYPE_INT | CTLFLAG_RW, 1161 NULL, 0, enable_sleepq_prof, "I", "Enable sleepqueue profiling"); 1162#endif 1163 1164#ifdef DDB 1165DB_SHOW_COMMAND(sleepq, db_show_sleepqueue) 1166{ 1167 struct sleepqueue_chain *sc; 1168 struct sleepqueue *sq; 1169#ifdef INVARIANTS 1170 struct lock_object *lock; 1171#endif 1172 struct thread *td; 1173 void *wchan; 1174 int i; 1175 1176 if (!have_addr) 1177 return; 1178 1179 /* 1180 * First, see if there is an active sleep queue for the wait channel 1181 * indicated by the address. 1182 */ 1183 wchan = (void *)addr; 1184 sc = SC_LOOKUP(wchan); 1185 LIST_FOREACH(sq, &sc->sc_queues, sq_hash) 1186 if (sq->sq_wchan == wchan) 1187 goto found; 1188 1189 /* 1190 * Second, see if there is an active sleep queue at the address 1191 * indicated. 1192 */ 1193 for (i = 0; i < SC_TABLESIZE; i++) 1194 LIST_FOREACH(sq, &sleepq_chains[i].sc_queues, sq_hash) { 1195 if (sq == (struct sleepqueue *)addr) 1196 goto found; 1197 } 1198 1199 db_printf("Unable to locate a sleep queue via %p\n", (void *)addr); 1200 return; 1201found: 1202 db_printf("Wait channel: %p\n", sq->sq_wchan); 1203 db_printf("Queue type: %d\n", sq->sq_type); 1204#ifdef INVARIANTS 1205 if (sq->sq_lock) { 1206 lock = sq->sq_lock; 1207 db_printf("Associated Interlock: %p - (%s) %s\n", lock, 1208 LOCK_CLASS(lock)->lc_name, lock->lo_name); 1209 } 1210#endif 1211 db_printf("Blocked threads:\n"); 1212 for (i = 0; i < NR_SLEEPQS; i++) { 1213 db_printf("\nQueue[%d]:\n", i); 1214 if (TAILQ_EMPTY(&sq->sq_blocked[i])) 1215 db_printf("\tempty\n"); 1216 else 1217 TAILQ_FOREACH(td, &sq->sq_blocked[i], 1218 td_slpq) { 1219 db_printf("\t%p (tid %d, pid %d, \"%s\")\n", td, 1220 td->td_tid, td->td_proc->p_pid, 1221 td->td_name); 1222 } 1223 db_printf("(expected: %u)\n", sq->sq_blockedcnt[i]); 1224 } 1225} 1226 1227/* Alias 'show sleepqueue' to 'show sleepq'. */ 1228DB_SHOW_ALIAS(sleepqueue, db_show_sleepqueue); 1229#endif 1230