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