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 * 3. Neither the name of the author nor the names of any co-contributors 14 * may be used to endorse or promote products derived from this software 15 * without specific prior written permission. 16 * 17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 20 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 27 * SUCH DAMAGE. 28 */ 29 30 /* 31 * Implementation of sleep queues used to hold queue of threads blocked on 32 * a wait channel. Sleep queues different from turnstiles in that wait 33 * channels are not owned by anyone, so there is no priority propagation. 34 * Sleep queues can also provide a timeout and can also be interrupted by 35 * signals. That said, there are several similarities between the turnstile 36 * and sleep queue implementations. (Note: turnstiles were implemented 37 * first.) For example, both use a hash table of the same size where each 38 * bucket is referred to as a "chain" that contains both a spin lock and 39 * a linked list of queues. An individual queue is located by using a hash 40 * to pick a chain, locking the chain, and then walking the chain searching 41 * for the queue. This means that a wait channel object does not need to 42 * embed it's queue head just as locks do not embed their turnstile queue 43 * head. Threads also carry around a sleep queue that they lend to the 44 * wait channel when blocking. Just as in turnstiles, the queue includes 45 * a free list of the sleep queues of other threads blocked on the same 46 * wait channel in the case of multiple waiters. 47 * 48 * Some additional functionality provided by sleep queues include the 49 * ability to set a timeout. The timeout is managed using a per-thread 50 * callout that resumes a thread if it is asleep. A thread may also 51 * catch signals while it is asleep (aka an interruptible sleep). The 52 * signal code uses sleepq_abort() to interrupt a sleeping thread. Finally, 53 * sleep queues also provide some extra assertions. One is not allowed to 54 * mix the sleep/wakeup and cv APIs for a given wait channel. Also, one 55 * must consistently use the same lock to synchronize with a wait channel, 56 * though this check is currently only a warning for sleep/wakeup due to 57 * pre-existing abuse of that API. The same lock must also be held when 58 * awakening threads, though that is currently only enforced for condition 59 * variables. 60 */ 61 62 #include <sys/cdefs.h> 63 __FBSDID("$FreeBSD$"); 64 65 #include "opt_sleepqueue_profiling.h" 66 #include "opt_ddb.h" 67 #include "opt_kdtrace.h" 68 #include "opt_sched.h" 69 70 #include <sys/param.h> 71 #include <sys/systm.h> 72 #include <sys/lock.h> 73 #include <sys/kernel.h> 74 #include <sys/ktr.h> 75 #include <sys/mutex.h> 76 #include <sys/proc.h> 77 #include <sys/sbuf.h> 78 #include <sys/sched.h> 79 #include <sys/sdt.h> 80 #include <sys/signalvar.h> 81 #include <sys/sleepqueue.h> 82 #include <sys/sysctl.h> 83 84 #include <vm/uma.h> 85 86 #ifdef DDB 87 #include <ddb/ddb.h> 88 #endif 89 90 /* 91 * Constants for the hash table of sleep queue chains. These constants are 92 * the same ones that 4BSD (and possibly earlier versions of BSD) used. 93 * Basically, we ignore the lower 8 bits of the address since most wait 94 * channel pointers are aligned and only look at the next 7 bits for the 95 * hash. SC_TABLESIZE must be a power of two for SC_MASK to work properly. 96 */ 97 #define SC_TABLESIZE 128 /* Must be power of 2. */ 98 #define SC_MASK (SC_TABLESIZE - 1) 99 #define SC_SHIFT 8 100 #define SC_HASH(wc) (((uintptr_t)(wc) >> SC_SHIFT) & SC_MASK) 101 #define SC_LOOKUP(wc) &sleepq_chains[SC_HASH(wc)] 102 #define NR_SLEEPQS 2 103 /* 104 * There two different lists of sleep queues. Both lists are connected 105 * via the sq_hash entries. The first list is the sleep queue chain list 106 * that a sleep queue is on when it is attached to a wait channel. The 107 * second list is the free list hung off of a sleep queue that is attached 108 * to a wait channel. 109 * 110 * Each sleep queue also contains the wait channel it is attached to, the 111 * list of threads blocked on that wait channel, flags specific to the 112 * wait channel, and the lock used to synchronize with a wait channel. 113 * The flags are used to catch mismatches between the various consumers 114 * of the sleep queue API (e.g. sleep/wakeup and condition variables). 115 * The lock pointer is only used when invariants are enabled for various 116 * debugging checks. 117 * 118 * Locking key: 119 * c - sleep queue chain lock 120 */ 121 struct sleepqueue { 122 TAILQ_HEAD(, thread) sq_blocked[NR_SLEEPQS]; /* (c) Blocked threads. */ 123 u_int sq_blockedcnt[NR_SLEEPQS]; /* (c) N. of blocked threads. */ 124 LIST_ENTRY(sleepqueue) sq_hash; /* (c) Chain and free list. */ 125 LIST_HEAD(, sleepqueue) sq_free; /* (c) Free queues. */ 126 void *sq_wchan; /* (c) Wait channel. */ 127 int sq_type; /* (c) Queue type. */ 128 #ifdef INVARIANTS 129 struct lock_object *sq_lock; /* (c) Associated lock. */ 130 #endif 131 }; 132 133 struct sleepqueue_chain { 134 LIST_HEAD(, sleepqueue) sc_queues; /* List of sleep queues. */ 135 struct mtx sc_lock; /* Spin lock for this chain. */ 136 #ifdef SLEEPQUEUE_PROFILING 137 u_int sc_depth; /* Length of sc_queues. */ 138 u_int sc_max_depth; /* Max length of sc_queues. */ 139 #endif 140 }; 141 142 #ifdef SLEEPQUEUE_PROFILING 143 u_int sleepq_max_depth; 144 static SYSCTL_NODE(_debug, OID_AUTO, sleepq, CTLFLAG_RD, 0, "sleepq profiling"); 145 static SYSCTL_NODE(_debug_sleepq, OID_AUTO, chains, CTLFLAG_RD, 0, 146 "sleepq chain stats"); 147 SYSCTL_UINT(_debug_sleepq, OID_AUTO, max_depth, CTLFLAG_RD, &sleepq_max_depth, 148 0, "maxmimum depth achieved of a single chain"); 149 150 static void sleepq_profile(const char *wmesg); 151 static int prof_enabled; 152 #endif 153 static struct sleepqueue_chain sleepq_chains[SC_TABLESIZE]; 154 static uma_zone_t sleepq_zone; 155 156 /* 157 * Prototypes for non-exported routines. 158 */ 159 static int sleepq_catch_signals(void *wchan, int pri); 160 static int sleepq_check_signals(void); 161 static int sleepq_check_timeout(void); 162 #ifdef INVARIANTS 163 static void sleepq_dtor(void *mem, int size, void *arg); 164 #endif 165 static int sleepq_init(void *mem, int size, int flags); 166 static int sleepq_resume_thread(struct sleepqueue *sq, struct thread *td, 167 int pri); 168 static void sleepq_switch(void *wchan, int pri); 169 static void sleepq_timeout(void *arg); 170 171 SDT_PROBE_DECLARE(sched, , , sleep); 172 SDT_PROBE_DECLARE(sched, , , wakeup); 173 174 /* 175 * Early initialization of sleep queues that is called from the sleepinit() 176 * SYSINIT. 177 */ 178 void 179 init_sleepqueues(void) 180 { 181 #ifdef SLEEPQUEUE_PROFILING 182 struct sysctl_oid *chain_oid; 183 char chain_name[10]; 184 #endif 185 int i; 186 187 for (i = 0; i < SC_TABLESIZE; i++) { 188 LIST_INIT(&sleepq_chains[i].sc_queues); 189 mtx_init(&sleepq_chains[i].sc_lock, "sleepq chain", NULL, 190 MTX_SPIN | MTX_RECURSE); 191 #ifdef SLEEPQUEUE_PROFILING 192 snprintf(chain_name, sizeof(chain_name), "%d", i); 193 chain_oid = SYSCTL_ADD_NODE(NULL, 194 SYSCTL_STATIC_CHILDREN(_debug_sleepq_chains), OID_AUTO, 195 chain_name, CTLFLAG_RD, NULL, "sleepq chain stats"); 196 SYSCTL_ADD_UINT(NULL, SYSCTL_CHILDREN(chain_oid), OID_AUTO, 197 "depth", CTLFLAG_RD, &sleepq_chains[i].sc_depth, 0, NULL); 198 SYSCTL_ADD_UINT(NULL, SYSCTL_CHILDREN(chain_oid), OID_AUTO, 199 "max_depth", CTLFLAG_RD, &sleepq_chains[i].sc_max_depth, 0, 200 NULL); 201 #endif 202 } 203 sleepq_zone = uma_zcreate("SLEEPQUEUE", sizeof(struct sleepqueue), 204 #ifdef INVARIANTS 205 NULL, sleepq_dtor, sleepq_init, NULL, UMA_ALIGN_CACHE, 0); 206 #else 207 NULL, NULL, sleepq_init, NULL, UMA_ALIGN_CACHE, 0); 208 #endif 209 210 thread0.td_sleepqueue = sleepq_alloc(); 211 } 212 213 /* 214 * Get a sleep queue for a new thread. 215 */ 216 struct sleepqueue * 217 sleepq_alloc(void) 218 { 219 220 return (uma_zalloc(sleepq_zone, M_WAITOK)); 221 } 222 223 /* 224 * Free a sleep queue when a thread is destroyed. 225 */ 226 void 227 sleepq_free(struct sleepqueue *sq) 228 { 229 230 uma_zfree(sleepq_zone, sq); 231 } 232 233 /* 234 * Lock the sleep queue chain associated with the specified wait channel. 235 */ 236 void 237 sleepq_lock(void *wchan) 238 { 239 struct sleepqueue_chain *sc; 240 241 sc = SC_LOOKUP(wchan); 242 mtx_lock_spin(&sc->sc_lock); 243 } 244 245 /* 246 * Look up the sleep queue associated with a given wait channel in the hash 247 * table locking the associated sleep queue chain. If no queue is found in 248 * the table, NULL is returned. 249 */ 250 struct sleepqueue * 251 sleepq_lookup(void *wchan) 252 { 253 struct sleepqueue_chain *sc; 254 struct sleepqueue *sq; 255 256 KASSERT(wchan != NULL, ("%s: invalid NULL wait channel", __func__)); 257 sc = SC_LOOKUP(wchan); 258 mtx_assert(&sc->sc_lock, MA_OWNED); 259 LIST_FOREACH(sq, &sc->sc_queues, sq_hash) 260 if (sq->sq_wchan == wchan) 261 return (sq); 262 return (NULL); 263 } 264 265 /* 266 * Unlock the sleep queue chain associated with a given wait channel. 267 */ 268 void 269 sleepq_release(void *wchan) 270 { 271 struct sleepqueue_chain *sc; 272 273 sc = SC_LOOKUP(wchan); 274 mtx_unlock_spin(&sc->sc_lock); 275 } 276 277 /* 278 * Places the current thread on the sleep queue for the specified wait 279 * channel. If INVARIANTS is enabled, then it associates the passed in 280 * lock with the sleepq to make sure it is held when that sleep queue is 281 * woken up. 282 */ 283 void 284 sleepq_add(void *wchan, struct lock_object *lock, const char *wmesg, int flags, 285 int queue) 286 { 287 struct sleepqueue_chain *sc; 288 struct sleepqueue *sq; 289 struct thread *td; 290 291 td = curthread; 292 sc = SC_LOOKUP(wchan); 293 mtx_assert(&sc->sc_lock, MA_OWNED); 294 MPASS(td->td_sleepqueue != NULL); 295 MPASS(wchan != NULL); 296 MPASS((queue >= 0) && (queue < NR_SLEEPQS)); 297 298 /* If this thread is not allowed to sleep, die a horrible death. */ 299 KASSERT(!(td->td_pflags & TDP_NOSLEEPING), 300 ("Trying sleep, but thread marked as sleeping prohibited")); 301 302 /* Look up the sleep queue associated with the wait channel 'wchan'. */ 303 sq = sleepq_lookup(wchan); 304 305 /* 306 * If the wait channel does not already have a sleep queue, use 307 * this thread's sleep queue. Otherwise, insert the current thread 308 * into the sleep queue already in use by this wait channel. 309 */ 310 if (sq == NULL) { 311 #ifdef INVARIANTS 312 int i; 313 314 sq = td->td_sleepqueue; 315 for (i = 0; i < NR_SLEEPQS; i++) { 316 KASSERT(TAILQ_EMPTY(&sq->sq_blocked[i]), 317 ("thread's sleep queue %d is not empty", i)); 318 KASSERT(sq->sq_blockedcnt[i] == 0, 319 ("thread's sleep queue %d count mismatches", i)); 320 } 321 KASSERT(LIST_EMPTY(&sq->sq_free), 322 ("thread's sleep queue has a non-empty free list")); 323 KASSERT(sq->sq_wchan == NULL, ("stale sq_wchan pointer")); 324 sq->sq_lock = lock; 325 #endif 326 #ifdef SLEEPQUEUE_PROFILING 327 sc->sc_depth++; 328 if (sc->sc_depth > sc->sc_max_depth) { 329 sc->sc_max_depth = sc->sc_depth; 330 if (sc->sc_max_depth > sleepq_max_depth) 331 sleepq_max_depth = sc->sc_max_depth; 332 } 333 #endif 334 sq = td->td_sleepqueue; 335 LIST_INSERT_HEAD(&sc->sc_queues, sq, sq_hash); 336 sq->sq_wchan = wchan; 337 sq->sq_type = flags & SLEEPQ_TYPE; 338 } else { 339 MPASS(wchan == sq->sq_wchan); 340 MPASS(lock == sq->sq_lock); 341 MPASS((flags & SLEEPQ_TYPE) == sq->sq_type); 342 LIST_INSERT_HEAD(&sq->sq_free, td->td_sleepqueue, sq_hash); 343 } 344 thread_lock(td); 345 TAILQ_INSERT_TAIL(&sq->sq_blocked[queue], td, td_slpq); 346 sq->sq_blockedcnt[queue]++; 347 td->td_sleepqueue = NULL; 348 td->td_sqqueue = queue; 349 td->td_wchan = wchan; 350 td->td_wmesg = wmesg; 351 if (flags & SLEEPQ_INTERRUPTIBLE) { 352 td->td_flags |= TDF_SINTR; 353 td->td_flags &= ~TDF_SLEEPABORT; 354 if (flags & SLEEPQ_STOP_ON_BDRY) 355 td->td_flags |= TDF_SBDRY; 356 } 357 thread_unlock(td); 358 } 359 360 /* 361 * Sets a timeout that will remove the current thread from the specified 362 * sleep queue after timo ticks if the thread has not already been awakened. 363 */ 364 void 365 sleepq_set_timeout(void *wchan, int timo) 366 { 367 struct sleepqueue_chain *sc; 368 struct thread *td; 369 370 td = curthread; 371 sc = SC_LOOKUP(wchan); 372 mtx_assert(&sc->sc_lock, MA_OWNED); 373 MPASS(TD_ON_SLEEPQ(td)); 374 MPASS(td->td_sleepqueue == NULL); 375 MPASS(wchan != NULL); 376 callout_reset_curcpu(&td->td_slpcallout, timo, sleepq_timeout, td); 377 } 378 379 /* 380 * Return the number of actual sleepers for the specified queue. 381 */ 382 u_int 383 sleepq_sleepcnt(void *wchan, int queue) 384 { 385 struct sleepqueue *sq; 386 387 KASSERT(wchan != NULL, ("%s: invalid NULL wait channel", __func__)); 388 MPASS((queue >= 0) && (queue < NR_SLEEPQS)); 389 sq = sleepq_lookup(wchan); 390 if (sq == NULL) 391 return (0); 392 return (sq->sq_blockedcnt[queue]); 393 } 394 395 /* 396 * Marks the pending sleep of the current thread as interruptible and 397 * makes an initial check for pending signals before putting a thread 398 * to sleep. Enters and exits with the thread lock held. Thread lock 399 * may have transitioned from the sleepq lock to a run lock. 400 */ 401 static int 402 sleepq_catch_signals(void *wchan, int pri) 403 { 404 struct sleepqueue_chain *sc; 405 struct sleepqueue *sq; 406 struct thread *td; 407 struct proc *p; 408 struct sigacts *ps; 409 int sig, ret, stop_allowed; 410 411 td = curthread; 412 p = curproc; 413 sc = SC_LOOKUP(wchan); 414 mtx_assert(&sc->sc_lock, MA_OWNED); 415 MPASS(wchan != NULL); 416 if ((td->td_pflags & TDP_WAKEUP) != 0) { 417 td->td_pflags &= ~TDP_WAKEUP; 418 ret = EINTR; 419 thread_lock(td); 420 goto out; 421 } 422 423 /* 424 * See if there are any pending signals for this thread. If not 425 * we can switch immediately. Otherwise do the signal processing 426 * directly. 427 */ 428 thread_lock(td); 429 if ((td->td_flags & (TDF_NEEDSIGCHK | TDF_NEEDSUSPCHK)) == 0) { 430 sleepq_switch(wchan, pri); 431 return (0); 432 } 433 stop_allowed = (td->td_flags & TDF_SBDRY) ? SIG_STOP_NOT_ALLOWED : 434 SIG_STOP_ALLOWED; 435 thread_unlock(td); 436 mtx_unlock_spin(&sc->sc_lock); 437 CTR3(KTR_PROC, "sleepq catching signals: thread %p (pid %ld, %s)", 438 (void *)td, (long)p->p_pid, td->td_name); 439 PROC_LOCK(p); 440 ps = p->p_sigacts; 441 mtx_lock(&ps->ps_mtx); 442 sig = cursig(td, stop_allowed); 443 if (sig == 0) { 444 mtx_unlock(&ps->ps_mtx); 445 ret = thread_suspend_check(1); 446 MPASS(ret == 0 || ret == EINTR || ret == ERESTART); 447 } else { 448 if (SIGISMEMBER(ps->ps_sigintr, sig)) 449 ret = EINTR; 450 else 451 ret = ERESTART; 452 mtx_unlock(&ps->ps_mtx); 453 } 454 /* 455 * Lock the per-process spinlock prior to dropping the PROC_LOCK 456 * to avoid a signal delivery race. PROC_LOCK, PROC_SLOCK, and 457 * thread_lock() are currently held in tdsendsignal(). 458 */ 459 PROC_SLOCK(p); 460 mtx_lock_spin(&sc->sc_lock); 461 PROC_UNLOCK(p); 462 thread_lock(td); 463 PROC_SUNLOCK(p); 464 if (ret == 0) { 465 sleepq_switch(wchan, pri); 466 return (0); 467 } 468 out: 469 /* 470 * There were pending signals and this thread is still 471 * on the sleep queue, remove it from the sleep queue. 472 */ 473 if (TD_ON_SLEEPQ(td)) { 474 sq = sleepq_lookup(wchan); 475 if (sleepq_resume_thread(sq, td, 0)) { 476 #ifdef INVARIANTS 477 /* 478 * This thread hasn't gone to sleep yet, so it 479 * should not be swapped out. 480 */ 481 panic("not waking up swapper"); 482 #endif 483 } 484 } 485 mtx_unlock_spin(&sc->sc_lock); 486 MPASS(td->td_lock != &sc->sc_lock); 487 return (ret); 488 } 489 490 /* 491 * Switches to another thread if we are still asleep on a sleep queue. 492 * Returns with thread lock. 493 */ 494 static void 495 sleepq_switch(void *wchan, int pri) 496 { 497 struct sleepqueue_chain *sc; 498 struct sleepqueue *sq; 499 struct thread *td; 500 501 td = curthread; 502 sc = SC_LOOKUP(wchan); 503 mtx_assert(&sc->sc_lock, MA_OWNED); 504 THREAD_LOCK_ASSERT(td, MA_OWNED); 505 506 /* 507 * If we have a sleep queue, then we've already been woken up, so 508 * just return. 509 */ 510 if (td->td_sleepqueue != NULL) { 511 mtx_unlock_spin(&sc->sc_lock); 512 return; 513 } 514 515 /* 516 * If TDF_TIMEOUT is set, then our sleep has been timed out 517 * already but we are still on the sleep queue, so dequeue the 518 * thread and return. 519 */ 520 if (td->td_flags & TDF_TIMEOUT) { 521 MPASS(TD_ON_SLEEPQ(td)); 522 sq = sleepq_lookup(wchan); 523 if (sleepq_resume_thread(sq, td, 0)) { 524 #ifdef INVARIANTS 525 /* 526 * This thread hasn't gone to sleep yet, so it 527 * should not be swapped out. 528 */ 529 panic("not waking up swapper"); 530 #endif 531 } 532 mtx_unlock_spin(&sc->sc_lock); 533 return; 534 } 535 #ifdef SLEEPQUEUE_PROFILING 536 if (prof_enabled) 537 sleepq_profile(td->td_wmesg); 538 #endif 539 MPASS(td->td_sleepqueue == NULL); 540 sched_sleep(td, pri); 541 thread_lock_set(td, &sc->sc_lock); 542 SDT_PROBE0(sched, , , sleep); 543 TD_SET_SLEEPING(td); 544 mi_switch(SW_VOL | SWT_SLEEPQ, NULL); 545 KASSERT(TD_IS_RUNNING(td), ("running but not TDS_RUNNING")); 546 CTR3(KTR_PROC, "sleepq resume: thread %p (pid %ld, %s)", 547 (void *)td, (long)td->td_proc->p_pid, (void *)td->td_name); 548 } 549 550 /* 551 * Check to see if we timed out. 552 */ 553 static int 554 sleepq_check_timeout(void) 555 { 556 struct thread *td; 557 558 td = curthread; 559 THREAD_LOCK_ASSERT(td, MA_OWNED); 560 561 /* 562 * If TDF_TIMEOUT is set, we timed out. 563 */ 564 if (td->td_flags & TDF_TIMEOUT) { 565 td->td_flags &= ~TDF_TIMEOUT; 566 return (EWOULDBLOCK); 567 } 568 569 /* 570 * If TDF_TIMOFAIL is set, the timeout ran after we had 571 * already been woken up. 572 */ 573 if (td->td_flags & TDF_TIMOFAIL) 574 td->td_flags &= ~TDF_TIMOFAIL; 575 576 /* 577 * If callout_stop() fails, then the timeout is running on 578 * another CPU, so synchronize with it to avoid having it 579 * accidentally wake up a subsequent sleep. 580 */ 581 else if (callout_stop(&td->td_slpcallout) == 0) { 582 td->td_flags |= TDF_TIMEOUT; 583 TD_SET_SLEEPING(td); 584 mi_switch(SW_INVOL | SWT_SLEEPQTIMO, NULL); 585 } 586 return (0); 587 } 588 589 /* 590 * Check to see if we were awoken by a signal. 591 */ 592 static int 593 sleepq_check_signals(void) 594 { 595 struct thread *td; 596 597 td = curthread; 598 THREAD_LOCK_ASSERT(td, MA_OWNED); 599 600 /* We are no longer in an interruptible sleep. */ 601 if (td->td_flags & TDF_SINTR) 602 td->td_flags &= ~(TDF_SINTR | TDF_SBDRY); 603 604 if (td->td_flags & TDF_SLEEPABORT) { 605 td->td_flags &= ~TDF_SLEEPABORT; 606 return (td->td_intrval); 607 } 608 609 return (0); 610 } 611 612 /* 613 * Block the current thread until it is awakened from its sleep queue. 614 */ 615 void 616 sleepq_wait(void *wchan, int pri) 617 { 618 struct thread *td; 619 620 td = curthread; 621 MPASS(!(td->td_flags & TDF_SINTR)); 622 thread_lock(td); 623 sleepq_switch(wchan, pri); 624 thread_unlock(td); 625 } 626 627 /* 628 * Block the current thread until it is awakened from its sleep queue 629 * or it is interrupted by a signal. 630 */ 631 int 632 sleepq_wait_sig(void *wchan, int pri) 633 { 634 int rcatch; 635 int rval; 636 637 rcatch = sleepq_catch_signals(wchan, pri); 638 rval = sleepq_check_signals(); 639 thread_unlock(curthread); 640 if (rcatch) 641 return (rcatch); 642 return (rval); 643 } 644 645 /* 646 * Block the current thread until it is awakened from its sleep queue 647 * or it times out while waiting. 648 */ 649 int 650 sleepq_timedwait(void *wchan, int pri) 651 { 652 struct thread *td; 653 int rval; 654 655 td = curthread; 656 MPASS(!(td->td_flags & TDF_SINTR)); 657 thread_lock(td); 658 sleepq_switch(wchan, pri); 659 rval = sleepq_check_timeout(); 660 thread_unlock(td); 661 662 return (rval); 663 } 664 665 /* 666 * Block the current thread until it is awakened from its sleep queue, 667 * it is interrupted by a signal, or it times out waiting to be awakened. 668 */ 669 int 670 sleepq_timedwait_sig(void *wchan, int pri) 671 { 672 int rcatch, rvalt, rvals; 673 674 rcatch = sleepq_catch_signals(wchan, pri); 675 rvalt = sleepq_check_timeout(); 676 rvals = sleepq_check_signals(); 677 thread_unlock(curthread); 678 if (rcatch) 679 return (rcatch); 680 if (rvals) 681 return (rvals); 682 return (rvalt); 683 } 684 685 /* 686 * Returns the type of sleepqueue given a waitchannel. 687 */ 688 int 689 sleepq_type(void *wchan) 690 { 691 struct sleepqueue *sq; 692 int type; 693 694 MPASS(wchan != NULL); 695 696 sleepq_lock(wchan); 697 sq = sleepq_lookup(wchan); 698 if (sq == NULL) { 699 sleepq_release(wchan); 700 return (-1); 701 } 702 type = sq->sq_type; 703 sleepq_release(wchan); 704 return (type); 705 } 706 707 /* 708 * Removes a thread from a sleep queue and makes it 709 * runnable. 710 */ 711 static int 712 sleepq_resume_thread(struct sleepqueue *sq, struct thread *td, int pri) 713 { 714 struct sleepqueue_chain *sc; 715 716 MPASS(td != NULL); 717 MPASS(sq->sq_wchan != NULL); 718 MPASS(td->td_wchan == sq->sq_wchan); 719 MPASS(td->td_sqqueue < NR_SLEEPQS && td->td_sqqueue >= 0); 720 THREAD_LOCK_ASSERT(td, MA_OWNED); 721 sc = SC_LOOKUP(sq->sq_wchan); 722 mtx_assert(&sc->sc_lock, MA_OWNED); 723 724 SDT_PROBE2(sched, , , wakeup, td, td->td_proc); 725 726 /* Remove the thread from the queue. */ 727 sq->sq_blockedcnt[td->td_sqqueue]--; 728 TAILQ_REMOVE(&sq->sq_blocked[td->td_sqqueue], td, td_slpq); 729 730 /* 731 * Get a sleep queue for this thread. If this is the last waiter, 732 * use the queue itself and take it out of the chain, otherwise, 733 * remove a queue from the free list. 734 */ 735 if (LIST_EMPTY(&sq->sq_free)) { 736 td->td_sleepqueue = sq; 737 #ifdef INVARIANTS 738 sq->sq_wchan = NULL; 739 #endif 740 #ifdef SLEEPQUEUE_PROFILING 741 sc->sc_depth--; 742 #endif 743 } else 744 td->td_sleepqueue = LIST_FIRST(&sq->sq_free); 745 LIST_REMOVE(td->td_sleepqueue, sq_hash); 746 747 td->td_wmesg = NULL; 748 td->td_wchan = NULL; 749 td->td_flags &= ~(TDF_SINTR | TDF_SBDRY); 750 751 CTR3(KTR_PROC, "sleepq_wakeup: thread %p (pid %ld, %s)", 752 (void *)td, (long)td->td_proc->p_pid, td->td_name); 753 754 /* Adjust priority if requested. */ 755 MPASS(pri == 0 || (pri >= PRI_MIN && pri <= PRI_MAX)); 756 if (pri != 0 && td->td_priority > pri && 757 PRI_BASE(td->td_pri_class) == PRI_TIMESHARE) 758 sched_prio(td, pri); 759 760 /* 761 * Note that thread td might not be sleeping if it is running 762 * sleepq_catch_signals() on another CPU or is blocked on its 763 * proc lock to check signals. There's no need to mark the 764 * thread runnable in that case. 765 */ 766 if (TD_IS_SLEEPING(td)) { 767 TD_CLR_SLEEPING(td); 768 return (setrunnable(td)); 769 } 770 return (0); 771 } 772 773 #ifdef INVARIANTS 774 /* 775 * UMA zone item deallocator. 776 */ 777 static void 778 sleepq_dtor(void *mem, int size, void *arg) 779 { 780 struct sleepqueue *sq; 781 int i; 782 783 sq = mem; 784 for (i = 0; i < NR_SLEEPQS; i++) { 785 MPASS(TAILQ_EMPTY(&sq->sq_blocked[i])); 786 MPASS(sq->sq_blockedcnt[i] == 0); 787 } 788 } 789 #endif 790 791 /* 792 * UMA zone item initializer. 793 */ 794 static int 795 sleepq_init(void *mem, int size, int flags) 796 { 797 struct sleepqueue *sq; 798 int i; 799 800 bzero(mem, size); 801 sq = mem; 802 for (i = 0; i < NR_SLEEPQS; i++) { 803 TAILQ_INIT(&sq->sq_blocked[i]); 804 sq->sq_blockedcnt[i] = 0; 805 } 806 LIST_INIT(&sq->sq_free); 807 return (0); 808 } 809 810 /* 811 * Find the highest priority thread sleeping on a wait channel and resume it. 812 */ 813 int 814 sleepq_signal(void *wchan, int flags, int pri, int queue) 815 { 816 struct sleepqueue *sq; 817 struct thread *td, *besttd; 818 int wakeup_swapper; 819 820 CTR2(KTR_PROC, "sleepq_signal(%p, %d)", wchan, flags); 821 KASSERT(wchan != NULL, ("%s: invalid NULL wait channel", __func__)); 822 MPASS((queue >= 0) && (queue < NR_SLEEPQS)); 823 sq = sleepq_lookup(wchan); 824 if (sq == NULL) 825 return (0); 826 KASSERT(sq->sq_type == (flags & SLEEPQ_TYPE), 827 ("%s: mismatch between sleep/wakeup and cv_*", __func__)); 828 829 /* 830 * Find the highest priority thread on the queue. If there is a 831 * tie, use the thread that first appears in the queue as it has 832 * been sleeping the longest since threads are always added to 833 * the tail of sleep queues. 834 */ 835 besttd = NULL; 836 TAILQ_FOREACH(td, &sq->sq_blocked[queue], td_slpq) { 837 if (besttd == NULL || td->td_priority < besttd->td_priority) 838 besttd = td; 839 } 840 MPASS(besttd != NULL); 841 thread_lock(besttd); 842 wakeup_swapper = sleepq_resume_thread(sq, besttd, pri); 843 thread_unlock(besttd); 844 return (wakeup_swapper); 845 } 846 847 /* 848 * Resume all threads sleeping on a specified wait channel. 849 */ 850 int 851 sleepq_broadcast(void *wchan, int flags, int pri, int queue) 852 { 853 struct sleepqueue *sq; 854 struct thread *td, *tdn; 855 int wakeup_swapper; 856 857 CTR2(KTR_PROC, "sleepq_broadcast(%p, %d)", wchan, flags); 858 KASSERT(wchan != NULL, ("%s: invalid NULL wait channel", __func__)); 859 MPASS((queue >= 0) && (queue < NR_SLEEPQS)); 860 sq = sleepq_lookup(wchan); 861 if (sq == NULL) 862 return (0); 863 KASSERT(sq->sq_type == (flags & SLEEPQ_TYPE), 864 ("%s: mismatch between sleep/wakeup and cv_*", __func__)); 865 866 /* Resume all blocked threads on the sleep queue. */ 867 wakeup_swapper = 0; 868 TAILQ_FOREACH_SAFE(td, &sq->sq_blocked[queue], td_slpq, tdn) { 869 thread_lock(td); 870 if (sleepq_resume_thread(sq, td, pri)) 871 wakeup_swapper = 1; 872 thread_unlock(td); 873 } 874 return (wakeup_swapper); 875 } 876 877 /* 878 * Time sleeping threads out. When the timeout expires, the thread is 879 * removed from the sleep queue and made runnable if it is still asleep. 880 */ 881 static void 882 sleepq_timeout(void *arg) 883 { 884 struct sleepqueue_chain *sc; 885 struct sleepqueue *sq; 886 struct thread *td; 887 void *wchan; 888 int wakeup_swapper; 889 890 td = arg; 891 wakeup_swapper = 0; 892 CTR3(KTR_PROC, "sleepq_timeout: thread %p (pid %ld, %s)", 893 (void *)td, (long)td->td_proc->p_pid, (void *)td->td_name); 894 895 /* 896 * First, see if the thread is asleep and get the wait channel if 897 * it is. 898 */ 899 thread_lock(td); 900 if (TD_IS_SLEEPING(td) && TD_ON_SLEEPQ(td)) { 901 wchan = td->td_wchan; 902 sc = SC_LOOKUP(wchan); 903 THREAD_LOCKPTR_ASSERT(td, &sc->sc_lock); 904 sq = sleepq_lookup(wchan); 905 MPASS(sq != NULL); 906 td->td_flags |= TDF_TIMEOUT; 907 wakeup_swapper = sleepq_resume_thread(sq, td, 0); 908 thread_unlock(td); 909 if (wakeup_swapper) 910 kick_proc0(); 911 return; 912 } 913 914 /* 915 * If the thread is on the SLEEPQ but isn't sleeping yet, it 916 * can either be on another CPU in between sleepq_add() and 917 * one of the sleepq_*wait*() routines or it can be in 918 * sleepq_catch_signals(). 919 */ 920 if (TD_ON_SLEEPQ(td)) { 921 td->td_flags |= TDF_TIMEOUT; 922 thread_unlock(td); 923 return; 924 } 925 926 /* 927 * Now check for the edge cases. First, if TDF_TIMEOUT is set, 928 * then the other thread has already yielded to us, so clear 929 * the flag and resume it. If TDF_TIMEOUT is not set, then the 930 * we know that the other thread is not on a sleep queue, but it 931 * hasn't resumed execution yet. In that case, set TDF_TIMOFAIL 932 * to let it know that the timeout has already run and doesn't 933 * need to be canceled. 934 */ 935 if (td->td_flags & TDF_TIMEOUT) { 936 MPASS(TD_IS_SLEEPING(td)); 937 td->td_flags &= ~TDF_TIMEOUT; 938 TD_CLR_SLEEPING(td); 939 wakeup_swapper = setrunnable(td); 940 } else 941 td->td_flags |= TDF_TIMOFAIL; 942 thread_unlock(td); 943 if (wakeup_swapper) 944 kick_proc0(); 945 } 946 947 /* 948 * Resumes a specific thread from the sleep queue associated with a specific 949 * wait channel if it is on that queue. 950 */ 951 void 952 sleepq_remove(struct thread *td, void *wchan) 953 { 954 struct sleepqueue *sq; 955 int wakeup_swapper; 956 957 /* 958 * Look up the sleep queue for this wait channel, then re-check 959 * that the thread is asleep on that channel, if it is not, then 960 * bail. 961 */ 962 MPASS(wchan != NULL); 963 sleepq_lock(wchan); 964 sq = sleepq_lookup(wchan); 965 /* 966 * We can not lock the thread here as it may be sleeping on a 967 * different sleepq. However, holding the sleepq lock for this 968 * wchan can guarantee that we do not miss a wakeup for this 969 * channel. The asserts below will catch any false positives. 970 */ 971 if (!TD_ON_SLEEPQ(td) || td->td_wchan != wchan) { 972 sleepq_release(wchan); 973 return; 974 } 975 /* Thread is asleep on sleep queue sq, so wake it up. */ 976 thread_lock(td); 977 MPASS(sq != NULL); 978 MPASS(td->td_wchan == wchan); 979 wakeup_swapper = sleepq_resume_thread(sq, td, 0); 980 thread_unlock(td); 981 sleepq_release(wchan); 982 if (wakeup_swapper) 983 kick_proc0(); 984 } 985 986 /* 987 * Abort a thread as if an interrupt had occurred. Only abort 988 * interruptible waits (unfortunately it isn't safe to abort others). 989 */ 990 int 991 sleepq_abort(struct thread *td, int intrval) 992 { 993 struct sleepqueue *sq; 994 void *wchan; 995 996 THREAD_LOCK_ASSERT(td, MA_OWNED); 997 MPASS(TD_ON_SLEEPQ(td)); 998 MPASS(td->td_flags & TDF_SINTR); 999 MPASS(intrval == EINTR || intrval == ERESTART); 1000 1001 /* 1002 * If the TDF_TIMEOUT flag is set, just leave. A 1003 * timeout is scheduled anyhow. 1004 */ 1005 if (td->td_flags & TDF_TIMEOUT) 1006 return (0); 1007 1008 CTR3(KTR_PROC, "sleepq_abort: thread %p (pid %ld, %s)", 1009 (void *)td, (long)td->td_proc->p_pid, (void *)td->td_name); 1010 td->td_intrval = intrval; 1011 td->td_flags |= TDF_SLEEPABORT; 1012 /* 1013 * If the thread has not slept yet it will find the signal in 1014 * sleepq_catch_signals() and call sleepq_resume_thread. Otherwise 1015 * we have to do it here. 1016 */ 1017 if (!TD_IS_SLEEPING(td)) 1018 return (0); 1019 wchan = td->td_wchan; 1020 MPASS(wchan != NULL); 1021 sq = sleepq_lookup(wchan); 1022 MPASS(sq != NULL); 1023 1024 /* Thread is asleep on sleep queue sq, so wake it up. */ 1025 return (sleepq_resume_thread(sq, td, 0)); 1026 } 1027 1028 #ifdef SLEEPQUEUE_PROFILING 1029 #define SLEEPQ_PROF_LOCATIONS 1024 1030 #define SLEEPQ_SBUFSIZE 512 1031 struct sleepq_prof { 1032 LIST_ENTRY(sleepq_prof) sp_link; 1033 const char *sp_wmesg; 1034 long sp_count; 1035 }; 1036 1037 LIST_HEAD(sqphead, sleepq_prof); 1038 1039 struct sqphead sleepq_prof_free; 1040 struct sqphead sleepq_hash[SC_TABLESIZE]; 1041 static struct sleepq_prof sleepq_profent[SLEEPQ_PROF_LOCATIONS]; 1042 static struct mtx sleepq_prof_lock; 1043 MTX_SYSINIT(sleepq_prof_lock, &sleepq_prof_lock, "sleepq_prof", MTX_SPIN); 1044 1045 static void 1046 sleepq_profile(const char *wmesg) 1047 { 1048 struct sleepq_prof *sp; 1049 1050 mtx_lock_spin(&sleepq_prof_lock); 1051 if (prof_enabled == 0) 1052 goto unlock; 1053 LIST_FOREACH(sp, &sleepq_hash[SC_HASH(wmesg)], sp_link) 1054 if (sp->sp_wmesg == wmesg) 1055 goto done; 1056 sp = LIST_FIRST(&sleepq_prof_free); 1057 if (sp == NULL) 1058 goto unlock; 1059 sp->sp_wmesg = wmesg; 1060 LIST_REMOVE(sp, sp_link); 1061 LIST_INSERT_HEAD(&sleepq_hash[SC_HASH(wmesg)], sp, sp_link); 1062 done: 1063 sp->sp_count++; 1064 unlock: 1065 mtx_unlock_spin(&sleepq_prof_lock); 1066 return; 1067 } 1068 1069 static void 1070 sleepq_prof_reset(void) 1071 { 1072 struct sleepq_prof *sp; 1073 int enabled; 1074 int i; 1075 1076 mtx_lock_spin(&sleepq_prof_lock); 1077 enabled = prof_enabled; 1078 prof_enabled = 0; 1079 for (i = 0; i < SC_TABLESIZE; i++) 1080 LIST_INIT(&sleepq_hash[i]); 1081 LIST_INIT(&sleepq_prof_free); 1082 for (i = 0; i < SLEEPQ_PROF_LOCATIONS; i++) { 1083 sp = &sleepq_profent[i]; 1084 sp->sp_wmesg = NULL; 1085 sp->sp_count = 0; 1086 LIST_INSERT_HEAD(&sleepq_prof_free, sp, sp_link); 1087 } 1088 prof_enabled = enabled; 1089 mtx_unlock_spin(&sleepq_prof_lock); 1090 } 1091 1092 static int 1093 enable_sleepq_prof(SYSCTL_HANDLER_ARGS) 1094 { 1095 int error, v; 1096 1097 v = prof_enabled; 1098 error = sysctl_handle_int(oidp, &v, v, req); 1099 if (error) 1100 return (error); 1101 if (req->newptr == NULL) 1102 return (error); 1103 if (v == prof_enabled) 1104 return (0); 1105 if (v == 1) 1106 sleepq_prof_reset(); 1107 mtx_lock_spin(&sleepq_prof_lock); 1108 prof_enabled = !!v; 1109 mtx_unlock_spin(&sleepq_prof_lock); 1110 1111 return (0); 1112 } 1113 1114 static int 1115 reset_sleepq_prof_stats(SYSCTL_HANDLER_ARGS) 1116 { 1117 int error, v; 1118 1119 v = 0; 1120 error = sysctl_handle_int(oidp, &v, 0, req); 1121 if (error) 1122 return (error); 1123 if (req->newptr == NULL) 1124 return (error); 1125 if (v == 0) 1126 return (0); 1127 sleepq_prof_reset(); 1128 1129 return (0); 1130 } 1131 1132 static int 1133 dump_sleepq_prof_stats(SYSCTL_HANDLER_ARGS) 1134 { 1135 struct sleepq_prof *sp; 1136 struct sbuf *sb; 1137 int enabled; 1138 int error; 1139 int i; 1140 1141 error = sysctl_wire_old_buffer(req, 0); 1142 if (error != 0) 1143 return (error); 1144 sb = sbuf_new_for_sysctl(NULL, NULL, SLEEPQ_SBUFSIZE, req); 1145 sbuf_printf(sb, "\nwmesg\tcount\n"); 1146 enabled = prof_enabled; 1147 mtx_lock_spin(&sleepq_prof_lock); 1148 prof_enabled = 0; 1149 mtx_unlock_spin(&sleepq_prof_lock); 1150 for (i = 0; i < SC_TABLESIZE; i++) { 1151 LIST_FOREACH(sp, &sleepq_hash[i], sp_link) { 1152 sbuf_printf(sb, "%s\t%ld\n", 1153 sp->sp_wmesg, sp->sp_count); 1154 } 1155 } 1156 mtx_lock_spin(&sleepq_prof_lock); 1157 prof_enabled = enabled; 1158 mtx_unlock_spin(&sleepq_prof_lock); 1159 1160 error = sbuf_finish(sb); 1161 sbuf_delete(sb); 1162 return (error); 1163 } 1164 1165 SYSCTL_PROC(_debug_sleepq, OID_AUTO, stats, CTLTYPE_STRING | CTLFLAG_RD, 1166 NULL, 0, dump_sleepq_prof_stats, "A", "Sleepqueue profiling statistics"); 1167 SYSCTL_PROC(_debug_sleepq, OID_AUTO, reset, CTLTYPE_INT | CTLFLAG_RW, 1168 NULL, 0, reset_sleepq_prof_stats, "I", 1169 "Reset sleepqueue profiling statistics"); 1170 SYSCTL_PROC(_debug_sleepq, OID_AUTO, enable, CTLTYPE_INT | CTLFLAG_RW, 1171 NULL, 0, enable_sleepq_prof, "I", "Enable sleepqueue profiling"); 1172 #endif 1173 1174 #ifdef DDB 1175 DB_SHOW_COMMAND(sleepq, db_show_sleepqueue) 1176 { 1177 struct sleepqueue_chain *sc; 1178 struct sleepqueue *sq; 1179 #ifdef INVARIANTS 1180 struct lock_object *lock; 1181 #endif 1182 struct thread *td; 1183 void *wchan; 1184 int i; 1185 1186 if (!have_addr) 1187 return; 1188 1189 /* 1190 * First, see if there is an active sleep queue for the wait channel 1191 * indicated by the address. 1192 */ 1193 wchan = (void *)addr; 1194 sc = SC_LOOKUP(wchan); 1195 LIST_FOREACH(sq, &sc->sc_queues, sq_hash) 1196 if (sq->sq_wchan == wchan) 1197 goto found; 1198 1199 /* 1200 * Second, see if there is an active sleep queue at the address 1201 * indicated. 1202 */ 1203 for (i = 0; i < SC_TABLESIZE; i++) 1204 LIST_FOREACH(sq, &sleepq_chains[i].sc_queues, sq_hash) { 1205 if (sq == (struct sleepqueue *)addr) 1206 goto found; 1207 } 1208 1209 db_printf("Unable to locate a sleep queue via %p\n", (void *)addr); 1210 return; 1211 found: 1212 db_printf("Wait channel: %p\n", sq->sq_wchan); 1213 db_printf("Queue type: %d\n", sq->sq_type); 1214 #ifdef INVARIANTS 1215 if (sq->sq_lock) { 1216 lock = sq->sq_lock; 1217 db_printf("Associated Interlock: %p - (%s) %s\n", lock, 1218 LOCK_CLASS(lock)->lc_name, lock->lo_name); 1219 } 1220 #endif 1221 db_printf("Blocked threads:\n"); 1222 for (i = 0; i < NR_SLEEPQS; i++) { 1223 db_printf("\nQueue[%d]:\n", i); 1224 if (TAILQ_EMPTY(&sq->sq_blocked[i])) 1225 db_printf("\tempty\n"); 1226 else 1227 TAILQ_FOREACH(td, &sq->sq_blocked[0], 1228 td_slpq) { 1229 db_printf("\t%p (tid %d, pid %d, \"%s\")\n", td, 1230 td->td_tid, td->td_proc->p_pid, 1231 td->td_name); 1232 } 1233 db_printf("(expected: %u)\n", sq->sq_blockedcnt[i]); 1234 } 1235 } 1236 1237 /* Alias 'show sleepqueue' to 'show sleepq'. */ 1238 DB_SHOW_ALIAS(sleepqueue, db_show_sleepqueue); 1239 #endif 1240