1/*- 2 * SPDX-License-Identifier: BSD-2-Clause 3 * 4 * Copyright (c) 2004 John Baldwin <jhb@FreeBSD.org> 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 16 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 18 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 19 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 21 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 22 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 23 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 24 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 25 * SUCH DAMAGE. 26 */ 27 28/* 29 * Implementation of sleep queues used to hold queue of threads blocked on 30 * a wait channel. Sleep queues are different from turnstiles in that wait 31 * channels are not owned by anyone, so there is no priority propagation. 32 * Sleep queues can also provide a timeout and can also be interrupted by 33 * signals. That said, there are several similarities between the turnstile 34 * and sleep queue implementations. (Note: turnstiles were implemented 35 * first.) For example, both use a hash table of the same size where each 36 * bucket is referred to as a "chain" that contains both a spin lock and 37 * a linked list of queues. An individual queue is located by using a hash 38 * to pick a chain, locking the chain, and then walking the chain searching 39 * for the queue. This means that a wait channel object does not need to 40 * embed its queue head just as locks do not embed their turnstile queue 41 * head. Threads also carry around a sleep queue that they lend to the 42 * wait channel when blocking. Just as in turnstiles, the queue includes 43 * a free list of the sleep queues of other threads blocked on the same 44 * wait channel in the case of multiple waiters. 45 * 46 * Some additional functionality provided by sleep queues include the 47 * ability to set a timeout. The timeout is managed using a per-thread 48 * callout that resumes a thread if it is asleep. A thread may also 49 * catch signals while it is asleep (aka an interruptible sleep). The 50 * signal code uses sleepq_abort() to interrupt a sleeping thread. Finally, 51 * sleep queues also provide some extra assertions. One is not allowed to 52 * mix the sleep/wakeup and cv APIs for a given wait channel. Also, one 53 * must consistently use the same lock to synchronize with a wait channel, 54 * though this check is currently only a warning for sleep/wakeup due to 55 * pre-existing abuse of that API. The same lock must also be held when 56 * awakening threads, though that is currently only enforced for condition 57 * variables. 58 */ 59 60#include <sys/cdefs.h> 61#include "opt_sleepqueue_profiling.h" 62#include "opt_ddb.h" 63#include "opt_sched.h" 64#include "opt_stack.h" 65 66#include <sys/param.h> 67#include <sys/systm.h> 68#include <sys/lock.h> 69#include <sys/kernel.h> 70#include <sys/ktr.h> 71#include <sys/mutex.h> 72#include <sys/proc.h> 73#include <sys/sbuf.h> 74#include <sys/sched.h> 75#include <sys/sdt.h> 76#include <sys/signalvar.h> 77#include <sys/sleepqueue.h> 78#include <sys/stack.h> 79#include <sys/sysctl.h> 80#include <sys/time.h> 81#ifdef EPOCH_TRACE 82#include <sys/epoch.h> 83#endif 84 85#include <machine/atomic.h> 86 87#include <vm/uma.h> 88 89#ifdef DDB 90#include <ddb/ddb.h> 91#endif 92 93/* 94 * Constants for the hash table of sleep queue chains. 95 * SC_TABLESIZE must be a power of two for SC_MASK to work properly. 96 */ 97#ifndef SC_TABLESIZE 98#define SC_TABLESIZE 256 99#endif 100CTASSERT(powerof2(SC_TABLESIZE)); 101#define SC_MASK (SC_TABLESIZE - 1) 102#define SC_SHIFT 8 103#define SC_HASH(wc) ((((uintptr_t)(wc) >> SC_SHIFT) ^ (uintptr_t)(wc)) & \ 104 SC_MASK) 105#define SC_LOOKUP(wc) &sleepq_chains[SC_HASH(wc)] 106#define NR_SLEEPQS 2 107/* 108 * There are two different lists of sleep queues. Both lists are connected 109 * via the sq_hash entries. The first list is the sleep queue chain list 110 * that a sleep queue is on when it is attached to a wait channel. The 111 * second list is the free list hung off of a sleep queue that is attached 112 * to a wait channel. 113 * 114 * Each sleep queue also contains the wait channel it is attached to, the 115 * list of threads blocked on that wait channel, flags specific to the 116 * wait channel, and the lock used to synchronize with a wait channel. 117 * The flags are used to catch mismatches between the various consumers 118 * of the sleep queue API (e.g. sleep/wakeup and condition variables). 119 * The lock pointer is only used when invariants are enabled for various 120 * debugging checks. 121 * 122 * Locking key: 123 * c - sleep queue chain lock 124 */ 125struct sleepqueue { 126 struct threadqueue sq_blocked[NR_SLEEPQS]; /* (c) Blocked threads. */ 127 u_int sq_blockedcnt[NR_SLEEPQS]; /* (c) N. of blocked threads. */ 128 LIST_ENTRY(sleepqueue) sq_hash; /* (c) Chain and free list. */ 129 LIST_HEAD(, sleepqueue) sq_free; /* (c) Free queues. */ 130 const void *sq_wchan; /* (c) Wait channel. */ 131 int sq_type; /* (c) Queue type. */ 132#ifdef INVARIANTS 133 struct lock_object *sq_lock; /* (c) Associated lock. */ 134#endif 135}; 136 137struct sleepqueue_chain { 138 LIST_HEAD(, sleepqueue) sc_queues; /* List of sleep queues. */ 139 struct mtx sc_lock; /* Spin lock for this chain. */ 140#ifdef SLEEPQUEUE_PROFILING 141 u_int sc_depth; /* Length of sc_queues. */ 142 u_int sc_max_depth; /* Max length of sc_queues. */ 143#endif 144} __aligned(CACHE_LINE_SIZE); 145 146#ifdef SLEEPQUEUE_PROFILING 147static SYSCTL_NODE(_debug, OID_AUTO, sleepq, CTLFLAG_RD | CTLFLAG_MPSAFE, 0, 148 "sleepq profiling"); 149static SYSCTL_NODE(_debug_sleepq, OID_AUTO, chains, 150 CTLFLAG_RD | CTLFLAG_MPSAFE, 0, 151 "sleepq chain stats"); 152static u_int sleepq_max_depth; 153SYSCTL_UINT(_debug_sleepq, OID_AUTO, max_depth, CTLFLAG_RD, &sleepq_max_depth, 154 0, "maxmimum depth achieved of a single chain"); 155 156static void sleepq_profile(const char *wmesg); 157static int prof_enabled; 158#endif 159static struct sleepqueue_chain sleepq_chains[SC_TABLESIZE]; 160static uma_zone_t sleepq_zone; 161 162/* 163 * Prototypes for non-exported routines. 164 */ 165static int sleepq_catch_signals(const void *wchan, int pri); 166static inline int sleepq_check_signals(void); 167static inline int sleepq_check_timeout(void); 168#ifdef INVARIANTS 169static void sleepq_dtor(void *mem, int size, void *arg); 170#endif 171static int sleepq_init(void *mem, int size, int flags); 172static int sleepq_resume_thread(struct sleepqueue *sq, struct thread *td, 173 int pri, int srqflags); 174static void sleepq_remove_thread(struct sleepqueue *sq, struct thread *td); 175static void sleepq_switch(const void *wchan, int pri); 176static void sleepq_timeout(void *arg); 177 178SDT_PROBE_DECLARE(sched, , , sleep); 179SDT_PROBE_DECLARE(sched, , , wakeup); 180 181/* 182 * Initialize SLEEPQUEUE_PROFILING specific sysctl nodes. 183 * Note that it must happen after sleepinit() has been fully executed, so 184 * it must happen after SI_SUB_KMEM SYSINIT() subsystem setup. 185 */ 186#ifdef SLEEPQUEUE_PROFILING 187static void 188init_sleepqueue_profiling(void) 189{ 190 char chain_name[10]; 191 struct sysctl_oid *chain_oid; 192 u_int i; 193 194 for (i = 0; i < SC_TABLESIZE; i++) { 195 snprintf(chain_name, sizeof(chain_name), "%u", i); 196 chain_oid = SYSCTL_ADD_NODE(NULL, 197 SYSCTL_STATIC_CHILDREN(_debug_sleepq_chains), OID_AUTO, 198 chain_name, CTLFLAG_RD | CTLFLAG_MPSAFE, NULL, 199 "sleepq chain stats"); 200 SYSCTL_ADD_UINT(NULL, SYSCTL_CHILDREN(chain_oid), OID_AUTO, 201 "depth", CTLFLAG_RD, &sleepq_chains[i].sc_depth, 0, NULL); 202 SYSCTL_ADD_UINT(NULL, SYSCTL_CHILDREN(chain_oid), OID_AUTO, 203 "max_depth", CTLFLAG_RD, &sleepq_chains[i].sc_max_depth, 0, 204 NULL); 205 } 206} 207 208SYSINIT(sleepqueue_profiling, SI_SUB_LOCK, SI_ORDER_ANY, 209 init_sleepqueue_profiling, NULL); 210#endif 211 212/* 213 * Early initialization of sleep queues that is called from the sleepinit() 214 * SYSINIT. 215 */ 216void 217init_sleepqueues(void) 218{ 219 int i; 220 221 for (i = 0; i < SC_TABLESIZE; i++) { 222 LIST_INIT(&sleepq_chains[i].sc_queues); 223 mtx_init(&sleepq_chains[i].sc_lock, "sleepq chain", NULL, 224 MTX_SPIN); 225 } 226 sleepq_zone = uma_zcreate("SLEEPQUEUE", sizeof(struct sleepqueue), 227#ifdef INVARIANTS 228 NULL, sleepq_dtor, sleepq_init, NULL, UMA_ALIGN_CACHE, 0); 229#else 230 NULL, NULL, sleepq_init, NULL, UMA_ALIGN_CACHE, 0); 231#endif 232 233 thread0.td_sleepqueue = sleepq_alloc(); 234} 235 236/* 237 * Get a sleep queue for a new thread. 238 */ 239struct sleepqueue * 240sleepq_alloc(void) 241{ 242 243 return (uma_zalloc(sleepq_zone, M_WAITOK)); 244} 245 246/* 247 * Free a sleep queue when a thread is destroyed. 248 */ 249void 250sleepq_free(struct sleepqueue *sq) 251{ 252 253 uma_zfree(sleepq_zone, sq); 254} 255 256/* 257 * Lock the sleep queue chain associated with the specified wait channel. 258 */ 259void 260sleepq_lock(const void *wchan) 261{ 262 struct sleepqueue_chain *sc; 263 264 sc = SC_LOOKUP(wchan); 265 mtx_lock_spin(&sc->sc_lock); 266} 267 268/* 269 * Look up the sleep queue associated with a given wait channel in the hash 270 * table locking the associated sleep queue chain. If no queue is found in 271 * the table, NULL is returned. 272 */ 273struct sleepqueue * 274sleepq_lookup(const void *wchan) 275{ 276 struct sleepqueue_chain *sc; 277 struct sleepqueue *sq; 278 279 KASSERT(wchan != NULL, ("%s: invalid NULL wait channel", __func__)); 280 sc = SC_LOOKUP(wchan); 281 mtx_assert(&sc->sc_lock, MA_OWNED); 282 LIST_FOREACH(sq, &sc->sc_queues, sq_hash) 283 if (sq->sq_wchan == wchan) 284 return (sq); 285 return (NULL); 286} 287 288/* 289 * Unlock the sleep queue chain associated with a given wait channel. 290 */ 291void 292sleepq_release(const void *wchan) 293{ 294 struct sleepqueue_chain *sc; 295 296 sc = SC_LOOKUP(wchan); 297 mtx_unlock_spin(&sc->sc_lock); 298} 299 300/* 301 * Places the current thread on the sleep queue for the specified wait 302 * channel. If INVARIANTS is enabled, then it associates the passed in 303 * lock with the sleepq to make sure it is held when that sleep queue is 304 * woken up. 305 */ 306void 307sleepq_add(const void *wchan, struct lock_object *lock, const char *wmesg, 308 int flags, int queue) 309{ 310 struct sleepqueue_chain *sc; 311 struct sleepqueue *sq; 312 struct thread *td; 313 314 td = curthread; 315 sc = SC_LOOKUP(wchan); 316 mtx_assert(&sc->sc_lock, MA_OWNED); 317 MPASS(td->td_sleepqueue != NULL); 318 MPASS(wchan != NULL); 319 MPASS((queue >= 0) && (queue < NR_SLEEPQS)); 320 321 /* If this thread is not allowed to sleep, die a horrible death. */ 322 if (__predict_false(!THREAD_CAN_SLEEP())) { 323#ifdef EPOCH_TRACE 324 epoch_trace_list(curthread); 325#endif 326 KASSERT(0, 327 ("%s: td %p to sleep on wchan %p with sleeping prohibited", 328 __func__, td, wchan)); 329 } 330 331 /* Look up the sleep queue associated with the wait channel 'wchan'. */ 332 sq = sleepq_lookup(wchan); 333 334 /* 335 * If the wait channel does not already have a sleep queue, use 336 * this thread's sleep queue. Otherwise, insert the current thread 337 * into the sleep queue already in use by this wait channel. 338 */ 339 if (sq == NULL) { 340#ifdef INVARIANTS 341 int i; 342 343 sq = td->td_sleepqueue; 344 for (i = 0; i < NR_SLEEPQS; i++) { 345 KASSERT(TAILQ_EMPTY(&sq->sq_blocked[i]), 346 ("thread's sleep queue %d is not empty", i)); 347 KASSERT(sq->sq_blockedcnt[i] == 0, 348 ("thread's sleep queue %d count mismatches", i)); 349 } 350 KASSERT(LIST_EMPTY(&sq->sq_free), 351 ("thread's sleep queue has a non-empty free list")); 352 KASSERT(sq->sq_wchan == NULL, ("stale sq_wchan pointer")); 353 sq->sq_lock = lock; 354#endif 355#ifdef SLEEPQUEUE_PROFILING 356 sc->sc_depth++; 357 if (sc->sc_depth > sc->sc_max_depth) { 358 sc->sc_max_depth = sc->sc_depth; 359 if (sc->sc_max_depth > sleepq_max_depth) 360 sleepq_max_depth = sc->sc_max_depth; 361 } 362#endif 363 sq = td->td_sleepqueue; 364 LIST_INSERT_HEAD(&sc->sc_queues, sq, sq_hash); 365 sq->sq_wchan = wchan; 366 sq->sq_type = flags & SLEEPQ_TYPE; 367 } else { 368 MPASS(wchan == sq->sq_wchan); 369 MPASS(lock == sq->sq_lock); 370 MPASS((flags & SLEEPQ_TYPE) == sq->sq_type); 371 LIST_INSERT_HEAD(&sq->sq_free, td->td_sleepqueue, sq_hash); 372 } 373 thread_lock(td); 374 TAILQ_INSERT_TAIL(&sq->sq_blocked[queue], td, td_slpq); 375 sq->sq_blockedcnt[queue]++; 376 td->td_sleepqueue = NULL; 377 td->td_sqqueue = queue; 378 td->td_wchan = wchan; 379 td->td_wmesg = wmesg; 380 if (flags & SLEEPQ_INTERRUPTIBLE) { 381 td->td_intrval = 0; 382 td->td_flags |= TDF_SINTR; 383 } 384 td->td_flags &= ~TDF_TIMEOUT; 385 thread_unlock(td); 386} 387 388/* 389 * Sets a timeout that will remove the current thread from the 390 * specified sleep queue at the specified time if the thread has not 391 * already been awakened. Flags are from C_* (callout) namespace. 392 */ 393void 394sleepq_set_timeout_sbt(const void *wchan, sbintime_t sbt, sbintime_t pr, 395 int flags) 396{ 397 struct sleepqueue_chain *sc __unused; 398 struct thread *td; 399 sbintime_t pr1; 400 401 td = curthread; 402 sc = SC_LOOKUP(wchan); 403 mtx_assert(&sc->sc_lock, MA_OWNED); 404 MPASS(TD_ON_SLEEPQ(td)); 405 MPASS(td->td_sleepqueue == NULL); 406 MPASS(wchan != NULL); 407 if (cold && td == &thread0) 408 panic("timed sleep before timers are working"); 409 KASSERT(td->td_sleeptimo == 0, ("td %d %p td_sleeptimo %jx", 410 td->td_tid, td, (uintmax_t)td->td_sleeptimo)); 411 thread_lock(td); 412 callout_when(sbt, pr, flags, &td->td_sleeptimo, &pr1); 413 thread_unlock(td); 414 callout_reset_sbt_on(&td->td_slpcallout, td->td_sleeptimo, pr1, 415 sleepq_timeout, td, PCPU_GET(cpuid), flags | C_PRECALC | 416 C_DIRECT_EXEC); 417} 418 419/* 420 * Return the number of actual sleepers for the specified queue. 421 */ 422u_int 423sleepq_sleepcnt(const void *wchan, int queue) 424{ 425 struct sleepqueue *sq; 426 427 KASSERT(wchan != NULL, ("%s: invalid NULL wait channel", __func__)); 428 MPASS((queue >= 0) && (queue < NR_SLEEPQS)); 429 sq = sleepq_lookup(wchan); 430 if (sq == NULL) 431 return (0); 432 return (sq->sq_blockedcnt[queue]); 433} 434 435static int 436sleepq_check_ast_sc_locked(struct thread *td, struct sleepqueue_chain *sc) 437{ 438 struct proc *p; 439 int ret; 440 441 mtx_assert(&sc->sc_lock, MA_OWNED); 442 443 if ((td->td_pflags & TDP_WAKEUP) != 0) { 444 td->td_pflags &= ~TDP_WAKEUP; 445 thread_lock(td); 446 return (EINTR); 447 } 448 449 /* 450 * See if there are any pending signals or suspension requests for this 451 * thread. If not, we can switch immediately. 452 */ 453 thread_lock(td); 454 if (!td_ast_pending(td, TDA_SIG) && !td_ast_pending(td, TDA_SUSPEND)) 455 return (0); 456 457 thread_unlock(td); 458 mtx_unlock_spin(&sc->sc_lock); 459 460 p = td->td_proc; 461 CTR3(KTR_PROC, "sleepq catching signals: thread %p (pid %ld, %s)", 462 (void *)td, (long)p->p_pid, td->td_name); 463 PROC_LOCK(p); 464 465 /* 466 * Check for suspension first. Checking for signals and then 467 * suspending could result in a missed signal, since a signal 468 * can be delivered while this thread is suspended. 469 */ 470 ret = sig_ast_checksusp(td); 471 if (ret != 0) { 472 PROC_UNLOCK(p); 473 mtx_lock_spin(&sc->sc_lock); 474 thread_lock(td); 475 return (ret); 476 } 477 478 ret = sig_ast_needsigchk(td); 479 480 /* 481 * Lock the per-process spinlock prior to dropping the 482 * PROC_LOCK to avoid a signal delivery race. 483 * PROC_LOCK, PROC_SLOCK, and thread_lock() are 484 * currently held in tdsendsignal() and thread_single(). 485 */ 486 PROC_SLOCK(p); 487 mtx_lock_spin(&sc->sc_lock); 488 PROC_UNLOCK(p); 489 thread_lock(td); 490 PROC_SUNLOCK(p); 491 492 return (ret); 493} 494 495/* 496 * Marks the pending sleep of the current thread as interruptible and 497 * makes an initial check for pending signals before putting a thread 498 * to sleep. Enters and exits with the thread lock held. Thread lock 499 * may have transitioned from the sleepq lock to a run lock. 500 */ 501static int 502sleepq_catch_signals(const void *wchan, int pri) 503{ 504 struct thread *td; 505 struct sleepqueue_chain *sc; 506 struct sleepqueue *sq; 507 int ret; 508 509 sc = SC_LOOKUP(wchan); 510 mtx_assert(&sc->sc_lock, MA_OWNED); 511 MPASS(wchan != NULL); 512 td = curthread; 513 514 ret = sleepq_check_ast_sc_locked(td, sc); 515 THREAD_LOCK_ASSERT(td, MA_OWNED); 516 mtx_assert(&sc->sc_lock, MA_OWNED); 517 518 if (ret == 0) { 519 /* 520 * No pending signals and no suspension requests found. 521 * Switch the thread off the cpu. 522 */ 523 sleepq_switch(wchan, pri); 524 } else { 525 /* 526 * There were pending signals and this thread is still 527 * on the sleep queue, remove it from the sleep queue. 528 */ 529 if (TD_ON_SLEEPQ(td)) { 530 sq = sleepq_lookup(wchan); 531 sleepq_remove_thread(sq, td); 532 } 533 MPASS(td->td_lock != &sc->sc_lock); 534 mtx_unlock_spin(&sc->sc_lock); 535 thread_unlock(td); 536 } 537 return (ret); 538} 539 540/* 541 * Switches to another thread if we are still asleep on a sleep queue. 542 * Returns with thread lock. 543 */ 544static void 545sleepq_switch(const void *wchan, int pri) 546{ 547 struct sleepqueue_chain *sc; 548 struct sleepqueue *sq; 549 struct thread *td; 550 bool rtc_changed; 551 552 td = curthread; 553 sc = SC_LOOKUP(wchan); 554 mtx_assert(&sc->sc_lock, MA_OWNED); 555 THREAD_LOCK_ASSERT(td, MA_OWNED); 556 557 /* 558 * If we have a sleep queue, then we've already been woken up, so 559 * just return. 560 */ 561 if (td->td_sleepqueue != NULL) { 562 mtx_unlock_spin(&sc->sc_lock); 563 thread_unlock(td); 564 return; 565 } 566 567 /* 568 * If TDF_TIMEOUT is set, then our sleep has been timed out 569 * already but we are still on the sleep queue, so dequeue the 570 * thread and return. 571 * 572 * Do the same if the real-time clock has been adjusted since this 573 * thread calculated its timeout based on that clock. This handles 574 * the following race: 575 * - The Ts thread needs to sleep until an absolute real-clock time. 576 * It copies the global rtc_generation into curthread->td_rtcgen, 577 * reads the RTC, and calculates a sleep duration based on that time. 578 * See umtxq_sleep() for an example. 579 * - The Tc thread adjusts the RTC, bumps rtc_generation, and wakes 580 * threads that are sleeping until an absolute real-clock time. 581 * See tc_setclock() and the POSIX specification of clock_settime(). 582 * - Ts reaches the code below. It holds the sleepqueue chain lock, 583 * so Tc has finished waking, so this thread must test td_rtcgen. 584 * (The declaration of td_rtcgen refers to this comment.) 585 */ 586 rtc_changed = td->td_rtcgen != 0 && td->td_rtcgen != rtc_generation; 587 if ((td->td_flags & TDF_TIMEOUT) || rtc_changed) { 588 if (rtc_changed) { 589 td->td_rtcgen = 0; 590 } 591 MPASS(TD_ON_SLEEPQ(td)); 592 sq = sleepq_lookup(wchan); 593 sleepq_remove_thread(sq, td); 594 mtx_unlock_spin(&sc->sc_lock); 595 thread_unlock(td); 596 return; 597 } 598#ifdef SLEEPQUEUE_PROFILING 599 if (prof_enabled) 600 sleepq_profile(td->td_wmesg); 601#endif 602 MPASS(td->td_sleepqueue == NULL); 603 sched_sleep(td, pri); 604 thread_lock_set(td, &sc->sc_lock); 605 SDT_PROBE0(sched, , , sleep); 606 TD_SET_SLEEPING(td); 607 mi_switch(SW_VOL | SWT_SLEEPQ); 608 KASSERT(TD_IS_RUNNING(td), ("running but not TDS_RUNNING")); 609 CTR3(KTR_PROC, "sleepq resume: thread %p (pid %ld, %s)", 610 (void *)td, (long)td->td_proc->p_pid, (void *)td->td_name); 611} 612 613/* 614 * Check to see if we timed out. 615 */ 616static inline int 617sleepq_check_timeout(void) 618{ 619 struct thread *td; 620 int res; 621 622 res = 0; 623 td = curthread; 624 if (td->td_sleeptimo != 0) { 625 if (td->td_sleeptimo <= sbinuptime()) 626 res = EWOULDBLOCK; 627 td->td_sleeptimo = 0; 628 } 629 return (res); 630} 631 632/* 633 * Check to see if we were awoken by a signal. 634 */ 635static inline int 636sleepq_check_signals(void) 637{ 638 struct thread *td; 639 640 td = curthread; 641 KASSERT((td->td_flags & TDF_SINTR) == 0, 642 ("thread %p still in interruptible sleep?", td)); 643 644 return (td->td_intrval); 645} 646 647/* 648 * Block the current thread until it is awakened from its sleep queue. 649 */ 650void 651sleepq_wait(const void *wchan, int pri) 652{ 653 struct thread *td; 654 655 td = curthread; 656 MPASS(!(td->td_flags & TDF_SINTR)); 657 thread_lock(td); 658 sleepq_switch(wchan, pri); 659} 660 661/* 662 * Block the current thread until it is awakened from its sleep queue 663 * or it is interrupted by a signal. 664 */ 665int 666sleepq_wait_sig(const void *wchan, int pri) 667{ 668 int rcatch; 669 670 rcatch = sleepq_catch_signals(wchan, pri); 671 if (rcatch) 672 return (rcatch); 673 return (sleepq_check_signals()); 674} 675 676/* 677 * Block the current thread until it is awakened from its sleep queue 678 * or it times out while waiting. 679 */ 680int 681sleepq_timedwait(const void *wchan, int pri) 682{ 683 struct thread *td; 684 685 td = curthread; 686 MPASS(!(td->td_flags & TDF_SINTR)); 687 688 thread_lock(td); 689 sleepq_switch(wchan, pri); 690 691 return (sleepq_check_timeout()); 692} 693 694/* 695 * Block the current thread until it is awakened from its sleep queue, 696 * it is interrupted by a signal, or it times out waiting to be awakened. 697 */ 698int 699sleepq_timedwait_sig(const void *wchan, int pri) 700{ 701 int rcatch, rvalt, rvals; 702 703 rcatch = sleepq_catch_signals(wchan, pri); 704 /* We must always call check_timeout() to clear sleeptimo. */ 705 rvalt = sleepq_check_timeout(); 706 rvals = sleepq_check_signals(); 707 if (rcatch) 708 return (rcatch); 709 if (rvals) 710 return (rvals); 711 return (rvalt); 712} 713 714/* 715 * Returns the type of sleepqueue given a waitchannel. 716 */ 717int 718sleepq_type(const void *wchan) 719{ 720 struct sleepqueue *sq; 721 int type; 722 723 MPASS(wchan != NULL); 724 725 sq = sleepq_lookup(wchan); 726 if (sq == NULL) 727 return (-1); 728 type = sq->sq_type; 729 730 return (type); 731} 732 733/* 734 * Removes a thread from a sleep queue and makes it 735 * runnable. 736 * 737 * Requires the sc chain locked on entry. If SRQ_HOLD is specified it will 738 * be locked on return. Returns without the thread lock held. 739 */ 740static int 741sleepq_resume_thread(struct sleepqueue *sq, struct thread *td, int pri, 742 int srqflags) 743{ 744 struct sleepqueue_chain *sc; 745 bool drop; 746 747 MPASS(td != NULL); 748 MPASS(sq->sq_wchan != NULL); 749 MPASS(td->td_wchan == sq->sq_wchan); 750 751 sc = SC_LOOKUP(sq->sq_wchan); 752 mtx_assert(&sc->sc_lock, MA_OWNED); 753 754 /* 755 * Avoid recursing on the chain lock. If the locks don't match we 756 * need to acquire the thread lock which setrunnable will drop for 757 * us. In this case we need to drop the chain lock afterwards. 758 * 759 * There is no race that will make td_lock equal to sc_lock because 760 * we hold sc_lock. 761 */ 762 drop = false; 763 if (!TD_IS_SLEEPING(td)) { 764 thread_lock(td); 765 drop = true; 766 } else 767 thread_lock_block_wait(td); 768 769 /* Remove thread from the sleepq. */ 770 sleepq_remove_thread(sq, td); 771 772 /* If we're done with the sleepqueue release it. */ 773 if ((srqflags & SRQ_HOLD) == 0 && drop) 774 mtx_unlock_spin(&sc->sc_lock); 775 776 /* Adjust priority if requested. */ 777 MPASS(pri == 0 || (pri >= PRI_MIN && pri <= PRI_MAX)); 778 if (pri != 0 && td->td_priority > pri && 779 PRI_BASE(td->td_pri_class) == PRI_TIMESHARE) 780 sched_prio(td, pri); 781 782 /* 783 * Note that thread td might not be sleeping if it is running 784 * sleepq_catch_signals() on another CPU or is blocked on its 785 * proc lock to check signals. There's no need to mark the 786 * thread runnable in that case. 787 */ 788 if (TD_IS_SLEEPING(td)) { 789 MPASS(!drop); 790 TD_CLR_SLEEPING(td); 791 return (setrunnable(td, srqflags)); 792 } 793 MPASS(drop); 794 thread_unlock(td); 795 796 return (0); 797} 798 799static void 800sleepq_remove_thread(struct sleepqueue *sq, struct thread *td) 801{ 802 struct sleepqueue_chain *sc __unused; 803 804 MPASS(td != NULL); 805 MPASS(sq->sq_wchan != NULL); 806 MPASS(td->td_wchan == sq->sq_wchan); 807 MPASS(td->td_sqqueue < NR_SLEEPQS && td->td_sqqueue >= 0); 808 THREAD_LOCK_ASSERT(td, MA_OWNED); 809 sc = SC_LOOKUP(sq->sq_wchan); 810 mtx_assert(&sc->sc_lock, MA_OWNED); 811 812 SDT_PROBE2(sched, , , wakeup, td, td->td_proc); 813 814 /* Remove the thread from the queue. */ 815 sq->sq_blockedcnt[td->td_sqqueue]--; 816 TAILQ_REMOVE(&sq->sq_blocked[td->td_sqqueue], td, td_slpq); 817 818 /* 819 * Get a sleep queue for this thread. If this is the last waiter, 820 * use the queue itself and take it out of the chain, otherwise, 821 * remove a queue from the free list. 822 */ 823 if (LIST_EMPTY(&sq->sq_free)) { 824 td->td_sleepqueue = sq; 825#ifdef INVARIANTS 826 sq->sq_wchan = NULL; 827#endif 828#ifdef SLEEPQUEUE_PROFILING 829 sc->sc_depth--; 830#endif 831 } else 832 td->td_sleepqueue = LIST_FIRST(&sq->sq_free); 833 LIST_REMOVE(td->td_sleepqueue, sq_hash); 834 835 if ((td->td_flags & TDF_TIMEOUT) == 0 && td->td_sleeptimo != 0 && 836 td->td_lock == &sc->sc_lock) { 837 /* 838 * We ignore the situation where timeout subsystem was 839 * unable to stop our callout. The struct thread is 840 * type-stable, the callout will use the correct 841 * memory when running. The checks of the 842 * td_sleeptimo value in this function and in 843 * sleepq_timeout() ensure that the thread does not 844 * get spurious wakeups, even if the callout was reset 845 * or thread reused. 846 * 847 * We also cannot safely stop the callout if a scheduler 848 * lock is held since softclock_thread() forces a lock 849 * order of callout lock -> scheduler lock. The thread 850 * lock will be a scheduler lock only if the thread is 851 * preparing to go to sleep, so this is hopefully a rare 852 * scenario. 853 */ 854 callout_stop(&td->td_slpcallout); 855 } 856 857 td->td_wmesg = NULL; 858 td->td_wchan = NULL; 859 td->td_flags &= ~(TDF_SINTR | TDF_TIMEOUT); 860 861 CTR3(KTR_PROC, "sleepq_wakeup: thread %p (pid %ld, %s)", 862 (void *)td, (long)td->td_proc->p_pid, td->td_name); 863} 864 865void 866sleepq_remove_nested(struct thread *td) 867{ 868 struct sleepqueue_chain *sc; 869 struct sleepqueue *sq; 870 const void *wchan; 871 872 MPASS(TD_ON_SLEEPQ(td)); 873 874 wchan = td->td_wchan; 875 sc = SC_LOOKUP(wchan); 876 mtx_lock_spin(&sc->sc_lock); 877 sq = sleepq_lookup(wchan); 878 MPASS(sq != NULL); 879 thread_lock(td); 880 sleepq_remove_thread(sq, td); 881 mtx_unlock_spin(&sc->sc_lock); 882 /* Returns with the thread lock owned. */ 883} 884 885#ifdef INVARIANTS 886/* 887 * UMA zone item deallocator. 888 */ 889static void 890sleepq_dtor(void *mem, int size, void *arg) 891{ 892 struct sleepqueue *sq; 893 int i; 894 895 sq = mem; 896 for (i = 0; i < NR_SLEEPQS; i++) { 897 MPASS(TAILQ_EMPTY(&sq->sq_blocked[i])); 898 MPASS(sq->sq_blockedcnt[i] == 0); 899 } 900} 901#endif 902 903/* 904 * UMA zone item initializer. 905 */ 906static int 907sleepq_init(void *mem, int size, int flags) 908{ 909 struct sleepqueue *sq; 910 int i; 911 912 bzero(mem, size); 913 sq = mem; 914 for (i = 0; i < NR_SLEEPQS; i++) { 915 TAILQ_INIT(&sq->sq_blocked[i]); 916 sq->sq_blockedcnt[i] = 0; 917 } 918 LIST_INIT(&sq->sq_free); 919 return (0); 920} 921 922/* 923 * Find thread sleeping on a wait channel and resume it. 924 */ 925int 926sleepq_signal(const void *wchan, int flags, int pri, int queue) 927{ 928 struct sleepqueue_chain *sc; 929 struct sleepqueue *sq; 930 struct threadqueue *head; 931 struct thread *td, *besttd; 932 int wakeup_swapper; 933 934 CTR2(KTR_PROC, "sleepq_signal(%p, %d)", wchan, flags); 935 KASSERT(wchan != NULL, ("%s: invalid NULL wait channel", __func__)); 936 MPASS((queue >= 0) && (queue < NR_SLEEPQS)); 937 sq = sleepq_lookup(wchan); 938 if (sq == NULL) { 939 if (flags & SLEEPQ_DROP) 940 sleepq_release(wchan); 941 return (0); 942 } 943 KASSERT(sq->sq_type == (flags & SLEEPQ_TYPE), 944 ("%s: mismatch between sleep/wakeup and cv_*", __func__)); 945 946 head = &sq->sq_blocked[queue]; 947 if (flags & SLEEPQ_UNFAIR) { 948 /* 949 * Find the most recently sleeping thread, but try to 950 * skip threads still in process of context switch to 951 * avoid spinning on the thread lock. 952 */ 953 sc = SC_LOOKUP(wchan); 954 besttd = TAILQ_LAST_FAST(head, thread, td_slpq); 955 while (besttd->td_lock != &sc->sc_lock) { 956 td = TAILQ_PREV_FAST(besttd, head, thread, td_slpq); 957 if (td == NULL) 958 break; 959 besttd = td; 960 } 961 } else { 962 /* 963 * Find the highest priority thread on the queue. If there 964 * is a tie, use the thread that first appears in the queue 965 * as it has been sleeping the longest since threads are 966 * always added to the tail of sleep queues. 967 */ 968 besttd = td = TAILQ_FIRST(head); 969 while ((td = TAILQ_NEXT(td, td_slpq)) != NULL) { 970 if (td->td_priority < besttd->td_priority) 971 besttd = td; 972 } 973 } 974 MPASS(besttd != NULL); 975 wakeup_swapper = sleepq_resume_thread(sq, besttd, pri, 976 (flags & SLEEPQ_DROP) ? 0 : SRQ_HOLD); 977 return (wakeup_swapper); 978} 979 980static bool 981match_any(struct thread *td __unused) 982{ 983 984 return (true); 985} 986 987/* 988 * Resume all threads sleeping on a specified wait channel. 989 */ 990int 991sleepq_broadcast(const void *wchan, int flags, int pri, int queue) 992{ 993 struct sleepqueue *sq; 994 995 CTR2(KTR_PROC, "sleepq_broadcast(%p, %d)", wchan, flags); 996 KASSERT(wchan != NULL, ("%s: invalid NULL wait channel", __func__)); 997 MPASS((queue >= 0) && (queue < NR_SLEEPQS)); 998 sq = sleepq_lookup(wchan); 999 if (sq == NULL) 1000 return (0); 1001 KASSERT(sq->sq_type == (flags & SLEEPQ_TYPE), 1002 ("%s: mismatch between sleep/wakeup and cv_*", __func__)); 1003 1004 return (sleepq_remove_matching(sq, queue, match_any, pri)); 1005} 1006 1007/* 1008 * Resume threads on the sleep queue that match the given predicate. 1009 */ 1010int 1011sleepq_remove_matching(struct sleepqueue *sq, int queue, 1012 bool (*matches)(struct thread *), int pri) 1013{ 1014 struct thread *td, *tdn; 1015 int wakeup_swapper; 1016 1017 /* 1018 * The last thread will be given ownership of sq and may 1019 * re-enqueue itself before sleepq_resume_thread() returns, 1020 * so we must cache the "next" queue item at the beginning 1021 * of the final iteration. 1022 */ 1023 wakeup_swapper = 0; 1024 TAILQ_FOREACH_SAFE(td, &sq->sq_blocked[queue], td_slpq, tdn) { 1025 if (matches(td)) 1026 wakeup_swapper |= sleepq_resume_thread(sq, td, pri, 1027 SRQ_HOLD); 1028 } 1029 1030 return (wakeup_swapper); 1031} 1032 1033/* 1034 * Time sleeping threads out. When the timeout expires, the thread is 1035 * removed from the sleep queue and made runnable if it is still asleep. 1036 */ 1037static void 1038sleepq_timeout(void *arg) 1039{ 1040 struct sleepqueue_chain *sc __unused; 1041 struct sleepqueue *sq; 1042 struct thread *td; 1043 const void *wchan; 1044 int wakeup_swapper; 1045 1046 td = arg; 1047 CTR3(KTR_PROC, "sleepq_timeout: thread %p (pid %ld, %s)", 1048 (void *)td, (long)td->td_proc->p_pid, (void *)td->td_name); 1049 1050 thread_lock(td); 1051 if (td->td_sleeptimo == 0 || 1052 td->td_sleeptimo > td->td_slpcallout.c_time) { 1053 /* 1054 * The thread does not want a timeout (yet). 1055 */ 1056 } else if (TD_IS_SLEEPING(td) && TD_ON_SLEEPQ(td)) { 1057 /* 1058 * See if the thread is asleep and get the wait 1059 * channel if it is. 1060 */ 1061 wchan = td->td_wchan; 1062 sc = SC_LOOKUP(wchan); 1063 THREAD_LOCKPTR_ASSERT(td, &sc->sc_lock); 1064 sq = sleepq_lookup(wchan); 1065 MPASS(sq != NULL); 1066 td->td_flags |= TDF_TIMEOUT; 1067 wakeup_swapper = sleepq_resume_thread(sq, td, 0, 0); 1068 if (wakeup_swapper) 1069 kick_proc0(); 1070 return; 1071 } else if (TD_ON_SLEEPQ(td)) { 1072 /* 1073 * If the thread is on the SLEEPQ but isn't sleeping 1074 * yet, it can either be on another CPU in between 1075 * sleepq_add() and one of the sleepq_*wait*() 1076 * routines or it can be in sleepq_catch_signals(). 1077 */ 1078 td->td_flags |= TDF_TIMEOUT; 1079 } 1080 thread_unlock(td); 1081} 1082 1083/* 1084 * Resumes a specific thread from the sleep queue associated with a specific 1085 * wait channel if it is on that queue. 1086 */ 1087void 1088sleepq_remove(struct thread *td, const void *wchan) 1089{ 1090 struct sleepqueue_chain *sc; 1091 struct sleepqueue *sq; 1092 int wakeup_swapper; 1093 1094 /* 1095 * Look up the sleep queue for this wait channel, then re-check 1096 * that the thread is asleep on that channel, if it is not, then 1097 * bail. 1098 */ 1099 MPASS(wchan != NULL); 1100 sc = SC_LOOKUP(wchan); 1101 mtx_lock_spin(&sc->sc_lock); 1102 /* 1103 * We can not lock the thread here as it may be sleeping on a 1104 * different sleepq. However, holding the sleepq lock for this 1105 * wchan can guarantee that we do not miss a wakeup for this 1106 * channel. The asserts below will catch any false positives. 1107 */ 1108 if (!TD_ON_SLEEPQ(td) || td->td_wchan != wchan) { 1109 mtx_unlock_spin(&sc->sc_lock); 1110 return; 1111 } 1112 1113 /* Thread is asleep on sleep queue sq, so wake it up. */ 1114 sq = sleepq_lookup(wchan); 1115 MPASS(sq != NULL); 1116 MPASS(td->td_wchan == wchan); 1117 wakeup_swapper = sleepq_resume_thread(sq, td, 0, 0); 1118 if (wakeup_swapper) 1119 kick_proc0(); 1120} 1121 1122/* 1123 * Abort a thread as if an interrupt had occurred. Only abort 1124 * interruptible waits (unfortunately it isn't safe to abort others). 1125 * 1126 * Requires thread lock on entry, releases on return. 1127 */ 1128int 1129sleepq_abort(struct thread *td, int intrval) 1130{ 1131 struct sleepqueue *sq; 1132 const void *wchan; 1133 1134 THREAD_LOCK_ASSERT(td, MA_OWNED); 1135 MPASS(TD_ON_SLEEPQ(td)); 1136 MPASS(td->td_flags & TDF_SINTR); 1137 MPASS((intrval == 0 && (td->td_flags & TDF_SIGWAIT) != 0) || 1138 intrval == EINTR || intrval == ERESTART); 1139 1140 /* 1141 * If the TDF_TIMEOUT flag is set, just leave. A 1142 * timeout is scheduled anyhow. 1143 */ 1144 if (td->td_flags & TDF_TIMEOUT) { 1145 thread_unlock(td); 1146 return (0); 1147 } 1148 1149 CTR3(KTR_PROC, "sleepq_abort: thread %p (pid %ld, %s)", 1150 (void *)td, (long)td->td_proc->p_pid, (void *)td->td_name); 1151 td->td_intrval = intrval; 1152 1153 /* 1154 * If the thread has not slept yet it will find the signal in 1155 * sleepq_catch_signals() and call sleepq_resume_thread. Otherwise 1156 * we have to do it here. 1157 */ 1158 if (!TD_IS_SLEEPING(td)) { 1159 thread_unlock(td); 1160 return (0); 1161 } 1162 wchan = td->td_wchan; 1163 MPASS(wchan != NULL); 1164 sq = sleepq_lookup(wchan); 1165 MPASS(sq != NULL); 1166 1167 /* Thread is asleep on sleep queue sq, so wake it up. */ 1168 return (sleepq_resume_thread(sq, td, 0, 0)); 1169} 1170 1171void 1172sleepq_chains_remove_matching(bool (*matches)(struct thread *)) 1173{ 1174 struct sleepqueue_chain *sc; 1175 struct sleepqueue *sq, *sq1; 1176 int i, wakeup_swapper; 1177 1178 wakeup_swapper = 0; 1179 for (sc = &sleepq_chains[0]; sc < sleepq_chains + SC_TABLESIZE; ++sc) { 1180 if (LIST_EMPTY(&sc->sc_queues)) { 1181 continue; 1182 } 1183 mtx_lock_spin(&sc->sc_lock); 1184 LIST_FOREACH_SAFE(sq, &sc->sc_queues, sq_hash, sq1) { 1185 for (i = 0; i < NR_SLEEPQS; ++i) { 1186 wakeup_swapper |= sleepq_remove_matching(sq, i, 1187 matches, 0); 1188 } 1189 } 1190 mtx_unlock_spin(&sc->sc_lock); 1191 } 1192 if (wakeup_swapper) { 1193 kick_proc0(); 1194 } 1195} 1196 1197/* 1198 * Prints the stacks of all threads presently sleeping on wchan/queue to 1199 * the sbuf sb. Sets count_stacks_printed to the number of stacks actually 1200 * printed. Typically, this will equal the number of threads sleeping on the 1201 * queue, but may be less if sb overflowed before all stacks were printed. 1202 */ 1203#ifdef STACK 1204int 1205sleepq_sbuf_print_stacks(struct sbuf *sb, const void *wchan, int queue, 1206 int *count_stacks_printed) 1207{ 1208 struct thread *td, *td_next; 1209 struct sleepqueue *sq; 1210 struct stack **st; 1211 struct sbuf **td_infos; 1212 int i, stack_idx, error, stacks_to_allocate; 1213 bool finished; 1214 1215 error = 0; 1216 finished = false; 1217 1218 KASSERT(wchan != NULL, ("%s: invalid NULL wait channel", __func__)); 1219 MPASS((queue >= 0) && (queue < NR_SLEEPQS)); 1220 1221 stacks_to_allocate = 10; 1222 for (i = 0; i < 3 && !finished ; i++) { 1223 /* We cannot malloc while holding the queue's spinlock, so 1224 * we do our mallocs now, and hope it is enough. If it 1225 * isn't, we will free these, drop the lock, malloc more, 1226 * and try again, up to a point. After that point we will 1227 * give up and report ENOMEM. We also cannot write to sb 1228 * during this time since the client may have set the 1229 * SBUF_AUTOEXTEND flag on their sbuf, which could cause a 1230 * malloc as we print to it. So we defer actually printing 1231 * to sb until after we drop the spinlock. 1232 */ 1233 1234 /* Where we will store the stacks. */ 1235 st = malloc(sizeof(struct stack *) * stacks_to_allocate, 1236 M_TEMP, M_WAITOK); 1237 for (stack_idx = 0; stack_idx < stacks_to_allocate; 1238 stack_idx++) 1239 st[stack_idx] = stack_create(M_WAITOK); 1240 1241 /* Where we will store the td name, tid, etc. */ 1242 td_infos = malloc(sizeof(struct sbuf *) * stacks_to_allocate, 1243 M_TEMP, M_WAITOK); 1244 for (stack_idx = 0; stack_idx < stacks_to_allocate; 1245 stack_idx++) 1246 td_infos[stack_idx] = sbuf_new(NULL, NULL, 1247 MAXCOMLEN + sizeof(struct thread *) * 2 + 40, 1248 SBUF_FIXEDLEN); 1249 1250 sleepq_lock(wchan); 1251 sq = sleepq_lookup(wchan); 1252 if (sq == NULL) { 1253 /* This sleepq does not exist; exit and return ENOENT. */ 1254 error = ENOENT; 1255 finished = true; 1256 sleepq_release(wchan); 1257 goto loop_end; 1258 } 1259 1260 stack_idx = 0; 1261 /* Save thread info */ 1262 TAILQ_FOREACH_SAFE(td, &sq->sq_blocked[queue], td_slpq, 1263 td_next) { 1264 if (stack_idx >= stacks_to_allocate) 1265 goto loop_end; 1266 1267 /* Note the td_lock is equal to the sleepq_lock here. */ 1268 (void)stack_save_td(st[stack_idx], td); 1269 1270 sbuf_printf(td_infos[stack_idx], "%d: %s %p", 1271 td->td_tid, td->td_name, td); 1272 1273 ++stack_idx; 1274 } 1275 1276 finished = true; 1277 sleepq_release(wchan); 1278 1279 /* Print the stacks */ 1280 for (i = 0; i < stack_idx; i++) { 1281 sbuf_finish(td_infos[i]); 1282 sbuf_printf(sb, "--- thread %s: ---\n", sbuf_data(td_infos[i])); 1283 stack_sbuf_print(sb, st[i]); 1284 sbuf_putc(sb, '\n'); 1285 1286 error = sbuf_error(sb); 1287 if (error == 0) 1288 *count_stacks_printed = stack_idx; 1289 } 1290 1291loop_end: 1292 if (!finished) 1293 sleepq_release(wchan); 1294 for (stack_idx = 0; stack_idx < stacks_to_allocate; 1295 stack_idx++) 1296 stack_destroy(st[stack_idx]); 1297 for (stack_idx = 0; stack_idx < stacks_to_allocate; 1298 stack_idx++) 1299 sbuf_delete(td_infos[stack_idx]); 1300 free(st, M_TEMP); 1301 free(td_infos, M_TEMP); 1302 stacks_to_allocate *= 10; 1303 } 1304 1305 if (!finished && error == 0) 1306 error = ENOMEM; 1307 1308 return (error); 1309} 1310#endif 1311 1312#ifdef SLEEPQUEUE_PROFILING 1313#define SLEEPQ_PROF_LOCATIONS 1024 1314#define SLEEPQ_SBUFSIZE 512 1315struct sleepq_prof { 1316 LIST_ENTRY(sleepq_prof) sp_link; 1317 const char *sp_wmesg; 1318 long sp_count; 1319}; 1320 1321LIST_HEAD(sqphead, sleepq_prof); 1322 1323struct sqphead sleepq_prof_free; 1324struct sqphead sleepq_hash[SC_TABLESIZE]; 1325static struct sleepq_prof sleepq_profent[SLEEPQ_PROF_LOCATIONS]; 1326static struct mtx sleepq_prof_lock; 1327MTX_SYSINIT(sleepq_prof_lock, &sleepq_prof_lock, "sleepq_prof", MTX_SPIN); 1328 1329static void 1330sleepq_profile(const char *wmesg) 1331{ 1332 struct sleepq_prof *sp; 1333 1334 mtx_lock_spin(&sleepq_prof_lock); 1335 if (prof_enabled == 0) 1336 goto unlock; 1337 LIST_FOREACH(sp, &sleepq_hash[SC_HASH(wmesg)], sp_link) 1338 if (sp->sp_wmesg == wmesg) 1339 goto done; 1340 sp = LIST_FIRST(&sleepq_prof_free); 1341 if (sp == NULL) 1342 goto unlock; 1343 sp->sp_wmesg = wmesg; 1344 LIST_REMOVE(sp, sp_link); 1345 LIST_INSERT_HEAD(&sleepq_hash[SC_HASH(wmesg)], sp, sp_link); 1346done: 1347 sp->sp_count++; 1348unlock: 1349 mtx_unlock_spin(&sleepq_prof_lock); 1350 return; 1351} 1352 1353static void 1354sleepq_prof_reset(void) 1355{ 1356 struct sleepq_prof *sp; 1357 int enabled; 1358 int i; 1359 1360 mtx_lock_spin(&sleepq_prof_lock); 1361 enabled = prof_enabled; 1362 prof_enabled = 0; 1363 for (i = 0; i < SC_TABLESIZE; i++) 1364 LIST_INIT(&sleepq_hash[i]); 1365 LIST_INIT(&sleepq_prof_free); 1366 for (i = 0; i < SLEEPQ_PROF_LOCATIONS; i++) { 1367 sp = &sleepq_profent[i]; 1368 sp->sp_wmesg = NULL; 1369 sp->sp_count = 0; 1370 LIST_INSERT_HEAD(&sleepq_prof_free, sp, sp_link); 1371 } 1372 prof_enabled = enabled; 1373 mtx_unlock_spin(&sleepq_prof_lock); 1374} 1375 1376static int 1377enable_sleepq_prof(SYSCTL_HANDLER_ARGS) 1378{ 1379 int error, v; 1380 1381 v = prof_enabled; 1382 error = sysctl_handle_int(oidp, &v, v, req); 1383 if (error) 1384 return (error); 1385 if (req->newptr == NULL) 1386 return (error); 1387 if (v == prof_enabled) 1388 return (0); 1389 if (v == 1) 1390 sleepq_prof_reset(); 1391 mtx_lock_spin(&sleepq_prof_lock); 1392 prof_enabled = !!v; 1393 mtx_unlock_spin(&sleepq_prof_lock); 1394 1395 return (0); 1396} 1397 1398static int 1399reset_sleepq_prof_stats(SYSCTL_HANDLER_ARGS) 1400{ 1401 int error, v; 1402 1403 v = 0; 1404 error = sysctl_handle_int(oidp, &v, 0, req); 1405 if (error) 1406 return (error); 1407 if (req->newptr == NULL) 1408 return (error); 1409 if (v == 0) 1410 return (0); 1411 sleepq_prof_reset(); 1412 1413 return (0); 1414} 1415 1416static int 1417dump_sleepq_prof_stats(SYSCTL_HANDLER_ARGS) 1418{ 1419 struct sleepq_prof *sp; 1420 struct sbuf *sb; 1421 int enabled; 1422 int error; 1423 int i; 1424 1425 error = sysctl_wire_old_buffer(req, 0); 1426 if (error != 0) 1427 return (error); 1428 sb = sbuf_new_for_sysctl(NULL, NULL, SLEEPQ_SBUFSIZE, req); 1429 sbuf_cat(sb, "\nwmesg\tcount\n"); 1430 enabled = prof_enabled; 1431 mtx_lock_spin(&sleepq_prof_lock); 1432 prof_enabled = 0; 1433 mtx_unlock_spin(&sleepq_prof_lock); 1434 for (i = 0; i < SC_TABLESIZE; i++) { 1435 LIST_FOREACH(sp, &sleepq_hash[i], sp_link) { 1436 sbuf_printf(sb, "%s\t%ld\n", 1437 sp->sp_wmesg, sp->sp_count); 1438 } 1439 } 1440 mtx_lock_spin(&sleepq_prof_lock); 1441 prof_enabled = enabled; 1442 mtx_unlock_spin(&sleepq_prof_lock); 1443 1444 error = sbuf_finish(sb); 1445 sbuf_delete(sb); 1446 return (error); 1447} 1448 1449SYSCTL_PROC(_debug_sleepq, OID_AUTO, stats, 1450 CTLTYPE_STRING | CTLFLAG_RD | CTLFLAG_NEEDGIANT, NULL, 0, 1451 dump_sleepq_prof_stats, "A", 1452 "Sleepqueue profiling statistics"); 1453SYSCTL_PROC(_debug_sleepq, OID_AUTO, reset, 1454 CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_MPSAFE, NULL, 0, 1455 reset_sleepq_prof_stats, "I", 1456 "Reset sleepqueue profiling statistics"); 1457SYSCTL_PROC(_debug_sleepq, OID_AUTO, enable, 1458 CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_MPSAFE, NULL, 0, 1459 enable_sleepq_prof, "I", 1460 "Enable sleepqueue profiling"); 1461#endif 1462 1463#ifdef DDB 1464DB_SHOW_COMMAND(sleepq, db_show_sleepqueue) 1465{ 1466 struct sleepqueue_chain *sc; 1467 struct sleepqueue *sq; 1468#ifdef INVARIANTS 1469 struct lock_object *lock; 1470#endif 1471 struct thread *td; 1472 void *wchan; 1473 int i; 1474 1475 if (!have_addr) 1476 return; 1477 1478 /* 1479 * First, see if there is an active sleep queue for the wait channel 1480 * indicated by the address. 1481 */ 1482 wchan = (void *)addr; 1483 sc = SC_LOOKUP(wchan); 1484 LIST_FOREACH(sq, &sc->sc_queues, sq_hash) 1485 if (sq->sq_wchan == wchan) 1486 goto found; 1487 1488 /* 1489 * Second, see if there is an active sleep queue at the address 1490 * indicated. 1491 */ 1492 for (i = 0; i < SC_TABLESIZE; i++) 1493 LIST_FOREACH(sq, &sleepq_chains[i].sc_queues, sq_hash) { 1494 if (sq == (struct sleepqueue *)addr) 1495 goto found; 1496 } 1497 1498 db_printf("Unable to locate a sleep queue via %p\n", (void *)addr); 1499 return; 1500found: 1501 db_printf("Wait channel: %p\n", sq->sq_wchan); 1502 db_printf("Queue type: %d\n", sq->sq_type); 1503#ifdef INVARIANTS 1504 if (sq->sq_lock) { 1505 lock = sq->sq_lock; 1506 db_printf("Associated Interlock: %p - (%s) %s\n", lock, 1507 LOCK_CLASS(lock)->lc_name, lock->lo_name); 1508 } 1509#endif 1510 db_printf("Blocked threads:\n"); 1511 for (i = 0; i < NR_SLEEPQS; i++) { 1512 db_printf("\nQueue[%d]:\n", i); 1513 if (TAILQ_EMPTY(&sq->sq_blocked[i])) 1514 db_printf("\tempty\n"); 1515 else 1516 TAILQ_FOREACH(td, &sq->sq_blocked[i], 1517 td_slpq) { 1518 db_printf("\t%p (tid %d, pid %d, \"%s\")\n", td, 1519 td->td_tid, td->td_proc->p_pid, 1520 td->td_name); 1521 } 1522 db_printf("(expected: %u)\n", sq->sq_blockedcnt[i]); 1523 } 1524} 1525 1526/* Alias 'show sleepqueue' to 'show sleepq'. */ 1527DB_SHOW_ALIAS(sleepqueue, db_show_sleepqueue); 1528#endif 1529