1 /*- 2 * Copyright (c) 1998 Berkeley Software Design, Inc. All rights reserved. 3 * 4 * Redistribution and use in source and binary forms, with or without 5 * modification, are permitted provided that the following conditions 6 * are met: 7 * 1. Redistributions of source code must retain the above copyright 8 * notice, this list of conditions and the following disclaimer. 9 * 2. Redistributions in binary form must reproduce the above copyright 10 * notice, this list of conditions and the following disclaimer in the 11 * documentation and/or other materials provided with the distribution. 12 * 3. Berkeley Software Design Inc's name may not be used to endorse or 13 * promote products derived from this software without specific prior 14 * written permission. 15 * 16 * THIS SOFTWARE IS PROVIDED BY BERKELEY SOFTWARE DESIGN INC ``AS IS'' AND 17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 19 * ARE DISCLAIMED. IN NO EVENT SHALL BERKELEY SOFTWARE DESIGN INC BE LIABLE 20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26 * SUCH DAMAGE. 27 * 28 * from BSDI $Id: mutex_witness.c,v 1.1.2.20 2000/04/27 03:10:27 cp Exp $ 29 * and BSDI $Id: synch_machdep.c,v 2.3.2.39 2000/04/27 03:10:25 cp Exp $ 30 */ 31 32 /* 33 * Implementation of turnstiles used to hold queue of threads blocked on 34 * non-sleepable locks. Sleepable locks use condition variables to 35 * implement their queues. Turnstiles differ from a sleep queue in that 36 * turnstile queue's are assigned to a lock held by an owning thread. Thus, 37 * when one thread is enqueued onto a turnstile, it can lend its priority 38 * to the owning thread. 39 * 40 * We wish to avoid bloating locks with an embedded turnstile and we do not 41 * want to use back-pointers in the locks for the same reason. Thus, we 42 * use a similar approach to that of Solaris 7 as described in Solaris 43 * Internals by Jim Mauro and Richard McDougall. Turnstiles are looked up 44 * in a hash table based on the address of the lock. Each entry in the 45 * hash table is a linked-lists of turnstiles and is called a turnstile 46 * chain. Each chain contains a spin mutex that protects all of the 47 * turnstiles in the chain. 48 * 49 * Each time a thread is created, a turnstile is allocated from a UMA zone 50 * and attached to that thread. When a thread blocks on a lock, if it is the 51 * first thread to block, it lends its turnstile to the lock. If the lock 52 * already has a turnstile, then it gives its turnstile to the lock's 53 * turnstile's free list. When a thread is woken up, it takes a turnstile from 54 * the free list if there are any other waiters. If it is the only thread 55 * blocked on the lock, then it reclaims the turnstile associated with the lock 56 * and removes it from the hash table. 57 */ 58 59 #include <sys/cdefs.h> 60 __FBSDID("$FreeBSD$"); 61 62 #include "opt_ddb.h" 63 #include "opt_kdtrace.h" 64 #include "opt_turnstile_profiling.h" 65 #include "opt_sched.h" 66 67 #include <sys/param.h> 68 #include <sys/systm.h> 69 #include <sys/kdb.h> 70 #include <sys/kernel.h> 71 #include <sys/ktr.h> 72 #include <sys/lock.h> 73 #include <sys/mutex.h> 74 #include <sys/proc.h> 75 #include <sys/queue.h> 76 #include <sys/sched.h> 77 #include <sys/sdt.h> 78 #include <sys/sysctl.h> 79 #include <sys/turnstile.h> 80 81 #include <vm/uma.h> 82 83 #ifdef DDB 84 #include <ddb/ddb.h> 85 #include <sys/lockmgr.h> 86 #include <sys/sx.h> 87 #endif 88 89 /* 90 * Constants for the hash table of turnstile chains. TC_SHIFT is a magic 91 * number chosen because the sleep queue's use the same value for the 92 * shift. Basically, we ignore the lower 8 bits of the address. 93 * TC_TABLESIZE must be a power of two for TC_MASK to work properly. 94 */ 95 #define TC_TABLESIZE 128 /* Must be power of 2. */ 96 #define TC_MASK (TC_TABLESIZE - 1) 97 #define TC_SHIFT 8 98 #define TC_HASH(lock) (((uintptr_t)(lock) >> TC_SHIFT) & TC_MASK) 99 #define TC_LOOKUP(lock) &turnstile_chains[TC_HASH(lock)] 100 101 /* 102 * There are three different lists of turnstiles as follows. The list 103 * connected by ts_link entries is a per-thread list of all the turnstiles 104 * attached to locks that we own. This is used to fixup our priority when 105 * a lock is released. The other two lists use the ts_hash entries. The 106 * first of these two is the turnstile chain list that a turnstile is on 107 * when it is attached to a lock. The second list to use ts_hash is the 108 * free list hung off of a turnstile that is attached to a lock. 109 * 110 * Each turnstile contains three lists of threads. The two ts_blocked lists 111 * are linked list of threads blocked on the turnstile's lock. One list is 112 * for exclusive waiters, and the other is for shared waiters. The 113 * ts_pending list is a linked list of threads previously awakened by 114 * turnstile_signal() or turnstile_wait() that are waiting to be put on 115 * the run queue. 116 * 117 * Locking key: 118 * c - turnstile chain lock 119 * q - td_contested lock 120 */ 121 struct turnstile { 122 struct mtx ts_lock; /* Spin lock for self. */ 123 struct threadqueue ts_blocked[2]; /* (c + q) Blocked threads. */ 124 struct threadqueue ts_pending; /* (c) Pending threads. */ 125 LIST_ENTRY(turnstile) ts_hash; /* (c) Chain and free list. */ 126 LIST_ENTRY(turnstile) ts_link; /* (q) Contested locks. */ 127 LIST_HEAD(, turnstile) ts_free; /* (c) Free turnstiles. */ 128 struct lock_object *ts_lockobj; /* (c) Lock we reference. */ 129 struct thread *ts_owner; /* (c + q) Who owns the lock. */ 130 }; 131 132 struct turnstile_chain { 133 LIST_HEAD(, turnstile) tc_turnstiles; /* List of turnstiles. */ 134 struct mtx tc_lock; /* Spin lock for this chain. */ 135 #ifdef TURNSTILE_PROFILING 136 u_int tc_depth; /* Length of tc_queues. */ 137 u_int tc_max_depth; /* Max length of tc_queues. */ 138 #endif 139 }; 140 141 #ifdef TURNSTILE_PROFILING 142 u_int turnstile_max_depth; 143 static SYSCTL_NODE(_debug, OID_AUTO, turnstile, CTLFLAG_RD, 0, 144 "turnstile profiling"); 145 static SYSCTL_NODE(_debug_turnstile, OID_AUTO, chains, CTLFLAG_RD, 0, 146 "turnstile chain stats"); 147 SYSCTL_UINT(_debug_turnstile, OID_AUTO, max_depth, CTLFLAG_RD, 148 &turnstile_max_depth, 0, "maximum depth achieved of a single chain"); 149 #endif 150 static struct mtx td_contested_lock; 151 static struct turnstile_chain turnstile_chains[TC_TABLESIZE]; 152 static uma_zone_t turnstile_zone; 153 154 /* 155 * Prototypes for non-exported routines. 156 */ 157 static void init_turnstile0(void *dummy); 158 #ifdef TURNSTILE_PROFILING 159 static void init_turnstile_profiling(void *arg); 160 #endif 161 static void propagate_priority(struct thread *td); 162 static int turnstile_adjust_thread(struct turnstile *ts, 163 struct thread *td); 164 static struct thread *turnstile_first_waiter(struct turnstile *ts); 165 static void turnstile_setowner(struct turnstile *ts, struct thread *owner); 166 #ifdef INVARIANTS 167 static void turnstile_dtor(void *mem, int size, void *arg); 168 #endif 169 static int turnstile_init(void *mem, int size, int flags); 170 static void turnstile_fini(void *mem, int size); 171 172 SDT_PROVIDER_DECLARE(sched); 173 SDT_PROBE_DEFINE(sched, , , sleep, sleep); 174 SDT_PROBE_DEFINE2(sched, , , wakeup, wakeup, "struct thread *", 175 "struct proc *"); 176 177 /* 178 * Walks the chain of turnstiles and their owners to propagate the priority 179 * of the thread being blocked to all the threads holding locks that have to 180 * release their locks before this thread can run again. 181 */ 182 static void 183 propagate_priority(struct thread *td) 184 { 185 struct turnstile *ts; 186 int pri; 187 188 THREAD_LOCK_ASSERT(td, MA_OWNED); 189 pri = td->td_priority; 190 ts = td->td_blocked; 191 THREAD_LOCKPTR_ASSERT(td, &ts->ts_lock); 192 /* 193 * Grab a recursive lock on this turnstile chain so it stays locked 194 * for the whole operation. The caller expects us to return with 195 * the original lock held. We only ever lock down the chain so 196 * the lock order is constant. 197 */ 198 mtx_lock_spin(&ts->ts_lock); 199 for (;;) { 200 td = ts->ts_owner; 201 202 if (td == NULL) { 203 /* 204 * This might be a read lock with no owner. There's 205 * not much we can do, so just bail. 206 */ 207 mtx_unlock_spin(&ts->ts_lock); 208 return; 209 } 210 211 thread_lock_flags(td, MTX_DUPOK); 212 mtx_unlock_spin(&ts->ts_lock); 213 MPASS(td->td_proc != NULL); 214 MPASS(td->td_proc->p_magic == P_MAGIC); 215 216 /* 217 * If the thread is asleep, then we are probably about 218 * to deadlock. To make debugging this easier, show 219 * backtrace of misbehaving thread and panic to not 220 * leave the kernel deadlocked. 221 */ 222 if (TD_IS_SLEEPING(td)) { 223 printf( 224 "Sleeping thread (tid %d, pid %d) owns a non-sleepable lock\n", 225 td->td_tid, td->td_proc->p_pid); 226 kdb_backtrace_thread(td); 227 panic("sleeping thread"); 228 } 229 230 /* 231 * If this thread already has higher priority than the 232 * thread that is being blocked, we are finished. 233 */ 234 if (td->td_priority <= pri) { 235 thread_unlock(td); 236 return; 237 } 238 239 /* 240 * Bump this thread's priority. 241 */ 242 sched_lend_prio(td, pri); 243 244 /* 245 * If lock holder is actually running or on the run queue 246 * then we are done. 247 */ 248 if (TD_IS_RUNNING(td) || TD_ON_RUNQ(td)) { 249 MPASS(td->td_blocked == NULL); 250 thread_unlock(td); 251 return; 252 } 253 254 #ifndef SMP 255 /* 256 * For UP, we check to see if td is curthread (this shouldn't 257 * ever happen however as it would mean we are in a deadlock.) 258 */ 259 KASSERT(td != curthread, ("Deadlock detected")); 260 #endif 261 262 /* 263 * If we aren't blocked on a lock, we should be. 264 */ 265 KASSERT(TD_ON_LOCK(td), ( 266 "thread %d(%s):%d holds %s but isn't blocked on a lock\n", 267 td->td_tid, td->td_name, td->td_state, 268 ts->ts_lockobj->lo_name)); 269 270 /* 271 * Pick up the lock that td is blocked on. 272 */ 273 ts = td->td_blocked; 274 MPASS(ts != NULL); 275 THREAD_LOCKPTR_ASSERT(td, &ts->ts_lock); 276 /* Resort td on the list if needed. */ 277 if (!turnstile_adjust_thread(ts, td)) { 278 mtx_unlock_spin(&ts->ts_lock); 279 return; 280 } 281 /* The thread lock is released as ts lock above. */ 282 } 283 } 284 285 /* 286 * Adjust the thread's position on a turnstile after its priority has been 287 * changed. 288 */ 289 static int 290 turnstile_adjust_thread(struct turnstile *ts, struct thread *td) 291 { 292 struct thread *td1, *td2; 293 int queue; 294 295 THREAD_LOCK_ASSERT(td, MA_OWNED); 296 MPASS(TD_ON_LOCK(td)); 297 298 /* 299 * This thread may not be blocked on this turnstile anymore 300 * but instead might already be woken up on another CPU 301 * that is waiting on the thread lock in turnstile_unpend() to 302 * finish waking this thread up. We can detect this case 303 * by checking to see if this thread has been given a 304 * turnstile by either turnstile_signal() or 305 * turnstile_broadcast(). In this case, treat the thread as 306 * if it was already running. 307 */ 308 if (td->td_turnstile != NULL) 309 return (0); 310 311 /* 312 * Check if the thread needs to be moved on the blocked chain. 313 * It needs to be moved if either its priority is lower than 314 * the previous thread or higher than the next thread. 315 */ 316 THREAD_LOCKPTR_ASSERT(td, &ts->ts_lock); 317 td1 = TAILQ_PREV(td, threadqueue, td_lockq); 318 td2 = TAILQ_NEXT(td, td_lockq); 319 if ((td1 != NULL && td->td_priority < td1->td_priority) || 320 (td2 != NULL && td->td_priority > td2->td_priority)) { 321 322 /* 323 * Remove thread from blocked chain and determine where 324 * it should be moved to. 325 */ 326 queue = td->td_tsqueue; 327 MPASS(queue == TS_EXCLUSIVE_QUEUE || queue == TS_SHARED_QUEUE); 328 mtx_lock_spin(&td_contested_lock); 329 TAILQ_REMOVE(&ts->ts_blocked[queue], td, td_lockq); 330 TAILQ_FOREACH(td1, &ts->ts_blocked[queue], td_lockq) { 331 MPASS(td1->td_proc->p_magic == P_MAGIC); 332 if (td1->td_priority > td->td_priority) 333 break; 334 } 335 336 if (td1 == NULL) 337 TAILQ_INSERT_TAIL(&ts->ts_blocked[queue], td, td_lockq); 338 else 339 TAILQ_INSERT_BEFORE(td1, td, td_lockq); 340 mtx_unlock_spin(&td_contested_lock); 341 if (td1 == NULL) 342 CTR3(KTR_LOCK, 343 "turnstile_adjust_thread: td %d put at tail on [%p] %s", 344 td->td_tid, ts->ts_lockobj, ts->ts_lockobj->lo_name); 345 else 346 CTR4(KTR_LOCK, 347 "turnstile_adjust_thread: td %d moved before %d on [%p] %s", 348 td->td_tid, td1->td_tid, ts->ts_lockobj, 349 ts->ts_lockobj->lo_name); 350 } 351 return (1); 352 } 353 354 /* 355 * Early initialization of turnstiles. This is not done via a SYSINIT() 356 * since this needs to be initialized very early when mutexes are first 357 * initialized. 358 */ 359 void 360 init_turnstiles(void) 361 { 362 int i; 363 364 for (i = 0; i < TC_TABLESIZE; i++) { 365 LIST_INIT(&turnstile_chains[i].tc_turnstiles); 366 mtx_init(&turnstile_chains[i].tc_lock, "turnstile chain", 367 NULL, MTX_SPIN); 368 } 369 mtx_init(&td_contested_lock, "td_contested", NULL, MTX_SPIN); 370 LIST_INIT(&thread0.td_contested); 371 thread0.td_turnstile = NULL; 372 } 373 374 #ifdef TURNSTILE_PROFILING 375 static void 376 init_turnstile_profiling(void *arg) 377 { 378 struct sysctl_oid *chain_oid; 379 char chain_name[10]; 380 int i; 381 382 for (i = 0; i < TC_TABLESIZE; i++) { 383 snprintf(chain_name, sizeof(chain_name), "%d", i); 384 chain_oid = SYSCTL_ADD_NODE(NULL, 385 SYSCTL_STATIC_CHILDREN(_debug_turnstile_chains), OID_AUTO, 386 chain_name, CTLFLAG_RD, NULL, "turnstile chain stats"); 387 SYSCTL_ADD_UINT(NULL, SYSCTL_CHILDREN(chain_oid), OID_AUTO, 388 "depth", CTLFLAG_RD, &turnstile_chains[i].tc_depth, 0, 389 NULL); 390 SYSCTL_ADD_UINT(NULL, SYSCTL_CHILDREN(chain_oid), OID_AUTO, 391 "max_depth", CTLFLAG_RD, &turnstile_chains[i].tc_max_depth, 392 0, NULL); 393 } 394 } 395 SYSINIT(turnstile_profiling, SI_SUB_LOCK, SI_ORDER_ANY, 396 init_turnstile_profiling, NULL); 397 #endif 398 399 static void 400 init_turnstile0(void *dummy) 401 { 402 403 turnstile_zone = uma_zcreate("TURNSTILE", sizeof(struct turnstile), 404 NULL, 405 #ifdef INVARIANTS 406 turnstile_dtor, 407 #else 408 NULL, 409 #endif 410 turnstile_init, turnstile_fini, UMA_ALIGN_CACHE, UMA_ZONE_NOFREE); 411 thread0.td_turnstile = turnstile_alloc(); 412 } 413 SYSINIT(turnstile0, SI_SUB_LOCK, SI_ORDER_ANY, init_turnstile0, NULL); 414 415 /* 416 * Update a thread on the turnstile list after it's priority has been changed. 417 * The old priority is passed in as an argument. 418 */ 419 void 420 turnstile_adjust(struct thread *td, u_char oldpri) 421 { 422 struct turnstile *ts; 423 424 MPASS(TD_ON_LOCK(td)); 425 426 /* 427 * Pick up the lock that td is blocked on. 428 */ 429 ts = td->td_blocked; 430 MPASS(ts != NULL); 431 THREAD_LOCKPTR_ASSERT(td, &ts->ts_lock); 432 mtx_assert(&ts->ts_lock, MA_OWNED); 433 434 /* Resort the turnstile on the list. */ 435 if (!turnstile_adjust_thread(ts, td)) 436 return; 437 /* 438 * If our priority was lowered and we are at the head of the 439 * turnstile, then propagate our new priority up the chain. 440 * Note that we currently don't try to revoke lent priorities 441 * when our priority goes up. 442 */ 443 MPASS(td->td_tsqueue == TS_EXCLUSIVE_QUEUE || 444 td->td_tsqueue == TS_SHARED_QUEUE); 445 if (td == TAILQ_FIRST(&ts->ts_blocked[td->td_tsqueue]) && 446 td->td_priority < oldpri) { 447 propagate_priority(td); 448 } 449 } 450 451 /* 452 * Set the owner of the lock this turnstile is attached to. 453 */ 454 static void 455 turnstile_setowner(struct turnstile *ts, struct thread *owner) 456 { 457 458 mtx_assert(&td_contested_lock, MA_OWNED); 459 MPASS(ts->ts_owner == NULL); 460 461 /* A shared lock might not have an owner. */ 462 if (owner == NULL) 463 return; 464 465 MPASS(owner->td_proc->p_magic == P_MAGIC); 466 ts->ts_owner = owner; 467 LIST_INSERT_HEAD(&owner->td_contested, ts, ts_link); 468 } 469 470 #ifdef INVARIANTS 471 /* 472 * UMA zone item deallocator. 473 */ 474 static void 475 turnstile_dtor(void *mem, int size, void *arg) 476 { 477 struct turnstile *ts; 478 479 ts = mem; 480 MPASS(TAILQ_EMPTY(&ts->ts_blocked[TS_EXCLUSIVE_QUEUE])); 481 MPASS(TAILQ_EMPTY(&ts->ts_blocked[TS_SHARED_QUEUE])); 482 MPASS(TAILQ_EMPTY(&ts->ts_pending)); 483 } 484 #endif 485 486 /* 487 * UMA zone item initializer. 488 */ 489 static int 490 turnstile_init(void *mem, int size, int flags) 491 { 492 struct turnstile *ts; 493 494 bzero(mem, size); 495 ts = mem; 496 TAILQ_INIT(&ts->ts_blocked[TS_EXCLUSIVE_QUEUE]); 497 TAILQ_INIT(&ts->ts_blocked[TS_SHARED_QUEUE]); 498 TAILQ_INIT(&ts->ts_pending); 499 LIST_INIT(&ts->ts_free); 500 mtx_init(&ts->ts_lock, "turnstile lock", NULL, MTX_SPIN | MTX_RECURSE); 501 return (0); 502 } 503 504 static void 505 turnstile_fini(void *mem, int size) 506 { 507 struct turnstile *ts; 508 509 ts = mem; 510 mtx_destroy(&ts->ts_lock); 511 } 512 513 /* 514 * Get a turnstile for a new thread. 515 */ 516 struct turnstile * 517 turnstile_alloc(void) 518 { 519 520 return (uma_zalloc(turnstile_zone, M_WAITOK)); 521 } 522 523 /* 524 * Free a turnstile when a thread is destroyed. 525 */ 526 void 527 turnstile_free(struct turnstile *ts) 528 { 529 530 uma_zfree(turnstile_zone, ts); 531 } 532 533 /* 534 * Lock the turnstile chain associated with the specified lock. 535 */ 536 void 537 turnstile_chain_lock(struct lock_object *lock) 538 { 539 struct turnstile_chain *tc; 540 541 tc = TC_LOOKUP(lock); 542 mtx_lock_spin(&tc->tc_lock); 543 } 544 545 struct turnstile * 546 turnstile_trywait(struct lock_object *lock) 547 { 548 struct turnstile_chain *tc; 549 struct turnstile *ts; 550 551 tc = TC_LOOKUP(lock); 552 mtx_lock_spin(&tc->tc_lock); 553 LIST_FOREACH(ts, &tc->tc_turnstiles, ts_hash) 554 if (ts->ts_lockobj == lock) { 555 mtx_lock_spin(&ts->ts_lock); 556 return (ts); 557 } 558 559 ts = curthread->td_turnstile; 560 MPASS(ts != NULL); 561 mtx_lock_spin(&ts->ts_lock); 562 KASSERT(ts->ts_lockobj == NULL, ("stale ts_lockobj pointer")); 563 ts->ts_lockobj = lock; 564 565 return (ts); 566 } 567 568 void 569 turnstile_cancel(struct turnstile *ts) 570 { 571 struct turnstile_chain *tc; 572 struct lock_object *lock; 573 574 mtx_assert(&ts->ts_lock, MA_OWNED); 575 576 mtx_unlock_spin(&ts->ts_lock); 577 lock = ts->ts_lockobj; 578 if (ts == curthread->td_turnstile) 579 ts->ts_lockobj = NULL; 580 tc = TC_LOOKUP(lock); 581 mtx_unlock_spin(&tc->tc_lock); 582 } 583 584 /* 585 * Look up the turnstile for a lock in the hash table locking the associated 586 * turnstile chain along the way. If no turnstile is found in the hash 587 * table, NULL is returned. 588 */ 589 struct turnstile * 590 turnstile_lookup(struct lock_object *lock) 591 { 592 struct turnstile_chain *tc; 593 struct turnstile *ts; 594 595 tc = TC_LOOKUP(lock); 596 mtx_assert(&tc->tc_lock, MA_OWNED); 597 LIST_FOREACH(ts, &tc->tc_turnstiles, ts_hash) 598 if (ts->ts_lockobj == lock) { 599 mtx_lock_spin(&ts->ts_lock); 600 return (ts); 601 } 602 return (NULL); 603 } 604 605 /* 606 * Unlock the turnstile chain associated with a given lock. 607 */ 608 void 609 turnstile_chain_unlock(struct lock_object *lock) 610 { 611 struct turnstile_chain *tc; 612 613 tc = TC_LOOKUP(lock); 614 mtx_unlock_spin(&tc->tc_lock); 615 } 616 617 /* 618 * Return a pointer to the thread waiting on this turnstile with the 619 * most important priority or NULL if the turnstile has no waiters. 620 */ 621 static struct thread * 622 turnstile_first_waiter(struct turnstile *ts) 623 { 624 struct thread *std, *xtd; 625 626 std = TAILQ_FIRST(&ts->ts_blocked[TS_SHARED_QUEUE]); 627 xtd = TAILQ_FIRST(&ts->ts_blocked[TS_EXCLUSIVE_QUEUE]); 628 if (xtd == NULL || (std != NULL && std->td_priority < xtd->td_priority)) 629 return (std); 630 return (xtd); 631 } 632 633 /* 634 * Take ownership of a turnstile and adjust the priority of the new 635 * owner appropriately. 636 */ 637 void 638 turnstile_claim(struct turnstile *ts) 639 { 640 struct thread *td, *owner; 641 struct turnstile_chain *tc; 642 643 mtx_assert(&ts->ts_lock, MA_OWNED); 644 MPASS(ts != curthread->td_turnstile); 645 646 owner = curthread; 647 mtx_lock_spin(&td_contested_lock); 648 turnstile_setowner(ts, owner); 649 mtx_unlock_spin(&td_contested_lock); 650 651 td = turnstile_first_waiter(ts); 652 MPASS(td != NULL); 653 MPASS(td->td_proc->p_magic == P_MAGIC); 654 THREAD_LOCKPTR_ASSERT(td, &ts->ts_lock); 655 656 /* 657 * Update the priority of the new owner if needed. 658 */ 659 thread_lock(owner); 660 if (td->td_priority < owner->td_priority) 661 sched_lend_prio(owner, td->td_priority); 662 thread_unlock(owner); 663 tc = TC_LOOKUP(ts->ts_lockobj); 664 mtx_unlock_spin(&ts->ts_lock); 665 mtx_unlock_spin(&tc->tc_lock); 666 } 667 668 /* 669 * Block the current thread on the turnstile assicated with 'lock'. This 670 * function will context switch and not return until this thread has been 671 * woken back up. This function must be called with the appropriate 672 * turnstile chain locked and will return with it unlocked. 673 */ 674 void 675 turnstile_wait(struct turnstile *ts, struct thread *owner, int queue) 676 { 677 struct turnstile_chain *tc; 678 struct thread *td, *td1; 679 struct lock_object *lock; 680 681 td = curthread; 682 mtx_assert(&ts->ts_lock, MA_OWNED); 683 if (owner) 684 MPASS(owner->td_proc->p_magic == P_MAGIC); 685 MPASS(queue == TS_SHARED_QUEUE || queue == TS_EXCLUSIVE_QUEUE); 686 687 /* 688 * If the lock does not already have a turnstile, use this thread's 689 * turnstile. Otherwise insert the current thread into the 690 * turnstile already in use by this lock. 691 */ 692 tc = TC_LOOKUP(ts->ts_lockobj); 693 mtx_assert(&tc->tc_lock, MA_OWNED); 694 if (ts == td->td_turnstile) { 695 #ifdef TURNSTILE_PROFILING 696 tc->tc_depth++; 697 if (tc->tc_depth > tc->tc_max_depth) { 698 tc->tc_max_depth = tc->tc_depth; 699 if (tc->tc_max_depth > turnstile_max_depth) 700 turnstile_max_depth = tc->tc_max_depth; 701 } 702 #endif 703 LIST_INSERT_HEAD(&tc->tc_turnstiles, ts, ts_hash); 704 KASSERT(TAILQ_EMPTY(&ts->ts_pending), 705 ("thread's turnstile has pending threads")); 706 KASSERT(TAILQ_EMPTY(&ts->ts_blocked[TS_EXCLUSIVE_QUEUE]), 707 ("thread's turnstile has exclusive waiters")); 708 KASSERT(TAILQ_EMPTY(&ts->ts_blocked[TS_SHARED_QUEUE]), 709 ("thread's turnstile has shared waiters")); 710 KASSERT(LIST_EMPTY(&ts->ts_free), 711 ("thread's turnstile has a non-empty free list")); 712 MPASS(ts->ts_lockobj != NULL); 713 mtx_lock_spin(&td_contested_lock); 714 TAILQ_INSERT_TAIL(&ts->ts_blocked[queue], td, td_lockq); 715 turnstile_setowner(ts, owner); 716 mtx_unlock_spin(&td_contested_lock); 717 } else { 718 TAILQ_FOREACH(td1, &ts->ts_blocked[queue], td_lockq) 719 if (td1->td_priority > td->td_priority) 720 break; 721 mtx_lock_spin(&td_contested_lock); 722 if (td1 != NULL) 723 TAILQ_INSERT_BEFORE(td1, td, td_lockq); 724 else 725 TAILQ_INSERT_TAIL(&ts->ts_blocked[queue], td, td_lockq); 726 MPASS(owner == ts->ts_owner); 727 mtx_unlock_spin(&td_contested_lock); 728 MPASS(td->td_turnstile != NULL); 729 LIST_INSERT_HEAD(&ts->ts_free, td->td_turnstile, ts_hash); 730 } 731 thread_lock(td); 732 thread_lock_set(td, &ts->ts_lock); 733 td->td_turnstile = NULL; 734 735 /* Save who we are blocked on and switch. */ 736 lock = ts->ts_lockobj; 737 td->td_tsqueue = queue; 738 td->td_blocked = ts; 739 td->td_lockname = lock->lo_name; 740 td->td_blktick = ticks; 741 TD_SET_LOCK(td); 742 mtx_unlock_spin(&tc->tc_lock); 743 propagate_priority(td); 744 745 if (LOCK_LOG_TEST(lock, 0)) 746 CTR4(KTR_LOCK, "%s: td %d blocked on [%p] %s", __func__, 747 td->td_tid, lock, lock->lo_name); 748 749 SDT_PROBE0(sched, , , sleep); 750 751 THREAD_LOCKPTR_ASSERT(td, &ts->ts_lock); 752 mi_switch(SW_VOL | SWT_TURNSTILE, NULL); 753 754 if (LOCK_LOG_TEST(lock, 0)) 755 CTR4(KTR_LOCK, "%s: td %d free from blocked on [%p] %s", 756 __func__, td->td_tid, lock, lock->lo_name); 757 thread_unlock(td); 758 } 759 760 /* 761 * Pick the highest priority thread on this turnstile and put it on the 762 * pending list. This must be called with the turnstile chain locked. 763 */ 764 int 765 turnstile_signal(struct turnstile *ts, int queue) 766 { 767 struct turnstile_chain *tc; 768 struct thread *td; 769 int empty; 770 771 MPASS(ts != NULL); 772 mtx_assert(&ts->ts_lock, MA_OWNED); 773 MPASS(curthread->td_proc->p_magic == P_MAGIC); 774 MPASS(ts->ts_owner == curthread || ts->ts_owner == NULL); 775 MPASS(queue == TS_SHARED_QUEUE || queue == TS_EXCLUSIVE_QUEUE); 776 777 /* 778 * Pick the highest priority thread blocked on this lock and 779 * move it to the pending list. 780 */ 781 td = TAILQ_FIRST(&ts->ts_blocked[queue]); 782 MPASS(td->td_proc->p_magic == P_MAGIC); 783 mtx_lock_spin(&td_contested_lock); 784 TAILQ_REMOVE(&ts->ts_blocked[queue], td, td_lockq); 785 mtx_unlock_spin(&td_contested_lock); 786 TAILQ_INSERT_TAIL(&ts->ts_pending, td, td_lockq); 787 788 /* 789 * If the turnstile is now empty, remove it from its chain and 790 * give it to the about-to-be-woken thread. Otherwise take a 791 * turnstile from the free list and give it to the thread. 792 */ 793 empty = TAILQ_EMPTY(&ts->ts_blocked[TS_EXCLUSIVE_QUEUE]) && 794 TAILQ_EMPTY(&ts->ts_blocked[TS_SHARED_QUEUE]); 795 if (empty) { 796 tc = TC_LOOKUP(ts->ts_lockobj); 797 mtx_assert(&tc->tc_lock, MA_OWNED); 798 MPASS(LIST_EMPTY(&ts->ts_free)); 799 #ifdef TURNSTILE_PROFILING 800 tc->tc_depth--; 801 #endif 802 } else 803 ts = LIST_FIRST(&ts->ts_free); 804 MPASS(ts != NULL); 805 LIST_REMOVE(ts, ts_hash); 806 td->td_turnstile = ts; 807 808 return (empty); 809 } 810 811 /* 812 * Put all blocked threads on the pending list. This must be called with 813 * the turnstile chain locked. 814 */ 815 void 816 turnstile_broadcast(struct turnstile *ts, int queue) 817 { 818 struct turnstile_chain *tc; 819 struct turnstile *ts1; 820 struct thread *td; 821 822 MPASS(ts != NULL); 823 mtx_assert(&ts->ts_lock, MA_OWNED); 824 MPASS(curthread->td_proc->p_magic == P_MAGIC); 825 MPASS(ts->ts_owner == curthread || ts->ts_owner == NULL); 826 /* 827 * We must have the chain locked so that we can remove the empty 828 * turnstile from the hash queue. 829 */ 830 tc = TC_LOOKUP(ts->ts_lockobj); 831 mtx_assert(&tc->tc_lock, MA_OWNED); 832 MPASS(queue == TS_SHARED_QUEUE || queue == TS_EXCLUSIVE_QUEUE); 833 834 /* 835 * Transfer the blocked list to the pending list. 836 */ 837 mtx_lock_spin(&td_contested_lock); 838 TAILQ_CONCAT(&ts->ts_pending, &ts->ts_blocked[queue], td_lockq); 839 mtx_unlock_spin(&td_contested_lock); 840 841 /* 842 * Give a turnstile to each thread. The last thread gets 843 * this turnstile if the turnstile is empty. 844 */ 845 TAILQ_FOREACH(td, &ts->ts_pending, td_lockq) { 846 if (LIST_EMPTY(&ts->ts_free)) { 847 MPASS(TAILQ_NEXT(td, td_lockq) == NULL); 848 ts1 = ts; 849 #ifdef TURNSTILE_PROFILING 850 tc->tc_depth--; 851 #endif 852 } else 853 ts1 = LIST_FIRST(&ts->ts_free); 854 MPASS(ts1 != NULL); 855 LIST_REMOVE(ts1, ts_hash); 856 td->td_turnstile = ts1; 857 } 858 } 859 860 /* 861 * Wakeup all threads on the pending list and adjust the priority of the 862 * current thread appropriately. This must be called with the turnstile 863 * chain locked. 864 */ 865 void 866 turnstile_unpend(struct turnstile *ts, int owner_type) 867 { 868 TAILQ_HEAD( ,thread) pending_threads; 869 struct turnstile *nts; 870 struct thread *td; 871 u_char cp, pri; 872 873 MPASS(ts != NULL); 874 mtx_assert(&ts->ts_lock, MA_OWNED); 875 MPASS(ts->ts_owner == curthread || ts->ts_owner == NULL); 876 MPASS(!TAILQ_EMPTY(&ts->ts_pending)); 877 878 /* 879 * Move the list of pending threads out of the turnstile and 880 * into a local variable. 881 */ 882 TAILQ_INIT(&pending_threads); 883 TAILQ_CONCAT(&pending_threads, &ts->ts_pending, td_lockq); 884 #ifdef INVARIANTS 885 if (TAILQ_EMPTY(&ts->ts_blocked[TS_EXCLUSIVE_QUEUE]) && 886 TAILQ_EMPTY(&ts->ts_blocked[TS_SHARED_QUEUE])) 887 ts->ts_lockobj = NULL; 888 #endif 889 /* 890 * Adjust the priority of curthread based on other contested 891 * locks it owns. Don't lower the priority below the base 892 * priority however. 893 */ 894 td = curthread; 895 pri = PRI_MAX; 896 thread_lock(td); 897 mtx_lock_spin(&td_contested_lock); 898 /* 899 * Remove the turnstile from this thread's list of contested locks 900 * since this thread doesn't own it anymore. New threads will 901 * not be blocking on the turnstile until it is claimed by a new 902 * owner. There might not be a current owner if this is a shared 903 * lock. 904 */ 905 if (ts->ts_owner != NULL) { 906 ts->ts_owner = NULL; 907 LIST_REMOVE(ts, ts_link); 908 } 909 LIST_FOREACH(nts, &td->td_contested, ts_link) { 910 cp = turnstile_first_waiter(nts)->td_priority; 911 if (cp < pri) 912 pri = cp; 913 } 914 mtx_unlock_spin(&td_contested_lock); 915 sched_unlend_prio(td, pri); 916 thread_unlock(td); 917 /* 918 * Wake up all the pending threads. If a thread is not blocked 919 * on a lock, then it is currently executing on another CPU in 920 * turnstile_wait() or sitting on a run queue waiting to resume 921 * in turnstile_wait(). Set a flag to force it to try to acquire 922 * the lock again instead of blocking. 923 */ 924 while (!TAILQ_EMPTY(&pending_threads)) { 925 td = TAILQ_FIRST(&pending_threads); 926 TAILQ_REMOVE(&pending_threads, td, td_lockq); 927 SDT_PROBE2(sched, , , wakeup, td, td->td_proc); 928 thread_lock(td); 929 THREAD_LOCKPTR_ASSERT(td, &ts->ts_lock); 930 MPASS(td->td_proc->p_magic == P_MAGIC); 931 MPASS(TD_ON_LOCK(td)); 932 TD_CLR_LOCK(td); 933 MPASS(TD_CAN_RUN(td)); 934 td->td_blocked = NULL; 935 td->td_lockname = NULL; 936 td->td_blktick = 0; 937 #ifdef INVARIANTS 938 td->td_tsqueue = 0xff; 939 #endif 940 sched_add(td, SRQ_BORING); 941 thread_unlock(td); 942 } 943 mtx_unlock_spin(&ts->ts_lock); 944 } 945 946 /* 947 * Give up ownership of a turnstile. This must be called with the 948 * turnstile chain locked. 949 */ 950 void 951 turnstile_disown(struct turnstile *ts) 952 { 953 struct thread *td; 954 u_char cp, pri; 955 956 MPASS(ts != NULL); 957 mtx_assert(&ts->ts_lock, MA_OWNED); 958 MPASS(ts->ts_owner == curthread); 959 MPASS(TAILQ_EMPTY(&ts->ts_pending)); 960 MPASS(!TAILQ_EMPTY(&ts->ts_blocked[TS_EXCLUSIVE_QUEUE]) || 961 !TAILQ_EMPTY(&ts->ts_blocked[TS_SHARED_QUEUE])); 962 963 /* 964 * Remove the turnstile from this thread's list of contested locks 965 * since this thread doesn't own it anymore. New threads will 966 * not be blocking on the turnstile until it is claimed by a new 967 * owner. 968 */ 969 mtx_lock_spin(&td_contested_lock); 970 ts->ts_owner = NULL; 971 LIST_REMOVE(ts, ts_link); 972 mtx_unlock_spin(&td_contested_lock); 973 974 /* 975 * Adjust the priority of curthread based on other contested 976 * locks it owns. Don't lower the priority below the base 977 * priority however. 978 */ 979 td = curthread; 980 pri = PRI_MAX; 981 thread_lock(td); 982 mtx_unlock_spin(&ts->ts_lock); 983 mtx_lock_spin(&td_contested_lock); 984 LIST_FOREACH(ts, &td->td_contested, ts_link) { 985 cp = turnstile_first_waiter(ts)->td_priority; 986 if (cp < pri) 987 pri = cp; 988 } 989 mtx_unlock_spin(&td_contested_lock); 990 sched_unlend_prio(td, pri); 991 thread_unlock(td); 992 } 993 994 /* 995 * Return the first thread in a turnstile. 996 */ 997 struct thread * 998 turnstile_head(struct turnstile *ts, int queue) 999 { 1000 #ifdef INVARIANTS 1001 1002 MPASS(ts != NULL); 1003 MPASS(queue == TS_SHARED_QUEUE || queue == TS_EXCLUSIVE_QUEUE); 1004 mtx_assert(&ts->ts_lock, MA_OWNED); 1005 #endif 1006 return (TAILQ_FIRST(&ts->ts_blocked[queue])); 1007 } 1008 1009 /* 1010 * Returns true if a sub-queue of a turnstile is empty. 1011 */ 1012 int 1013 turnstile_empty(struct turnstile *ts, int queue) 1014 { 1015 #ifdef INVARIANTS 1016 1017 MPASS(ts != NULL); 1018 MPASS(queue == TS_SHARED_QUEUE || queue == TS_EXCLUSIVE_QUEUE); 1019 mtx_assert(&ts->ts_lock, MA_OWNED); 1020 #endif 1021 return (TAILQ_EMPTY(&ts->ts_blocked[queue])); 1022 } 1023 1024 #ifdef DDB 1025 static void 1026 print_thread(struct thread *td, const char *prefix) 1027 { 1028 1029 db_printf("%s%p (tid %d, pid %d, \"%s\")\n", prefix, td, td->td_tid, 1030 td->td_proc->p_pid, td->td_name[0] != '\0' ? td->td_name : 1031 td->td_name); 1032 } 1033 1034 static void 1035 print_queue(struct threadqueue *queue, const char *header, const char *prefix) 1036 { 1037 struct thread *td; 1038 1039 db_printf("%s:\n", header); 1040 if (TAILQ_EMPTY(queue)) { 1041 db_printf("%sempty\n", prefix); 1042 return; 1043 } 1044 TAILQ_FOREACH(td, queue, td_lockq) { 1045 print_thread(td, prefix); 1046 } 1047 } 1048 1049 DB_SHOW_COMMAND(turnstile, db_show_turnstile) 1050 { 1051 struct turnstile_chain *tc; 1052 struct turnstile *ts; 1053 struct lock_object *lock; 1054 int i; 1055 1056 if (!have_addr) 1057 return; 1058 1059 /* 1060 * First, see if there is an active turnstile for the lock indicated 1061 * by the address. 1062 */ 1063 lock = (struct lock_object *)addr; 1064 tc = TC_LOOKUP(lock); 1065 LIST_FOREACH(ts, &tc->tc_turnstiles, ts_hash) 1066 if (ts->ts_lockobj == lock) 1067 goto found; 1068 1069 /* 1070 * Second, see if there is an active turnstile at the address 1071 * indicated. 1072 */ 1073 for (i = 0; i < TC_TABLESIZE; i++) 1074 LIST_FOREACH(ts, &turnstile_chains[i].tc_turnstiles, ts_hash) { 1075 if (ts == (struct turnstile *)addr) 1076 goto found; 1077 } 1078 1079 db_printf("Unable to locate a turnstile via %p\n", (void *)addr); 1080 return; 1081 found: 1082 lock = ts->ts_lockobj; 1083 db_printf("Lock: %p - (%s) %s\n", lock, LOCK_CLASS(lock)->lc_name, 1084 lock->lo_name); 1085 if (ts->ts_owner) 1086 print_thread(ts->ts_owner, "Lock Owner: "); 1087 else 1088 db_printf("Lock Owner: none\n"); 1089 print_queue(&ts->ts_blocked[TS_SHARED_QUEUE], "Shared Waiters", "\t"); 1090 print_queue(&ts->ts_blocked[TS_EXCLUSIVE_QUEUE], "Exclusive Waiters", 1091 "\t"); 1092 print_queue(&ts->ts_pending, "Pending Threads", "\t"); 1093 1094 } 1095 1096 /* 1097 * Show all the threads a particular thread is waiting on based on 1098 * non-sleepable and non-spin locks. 1099 */ 1100 static void 1101 print_lockchain(struct thread *td, const char *prefix) 1102 { 1103 struct lock_object *lock; 1104 struct lock_class *class; 1105 struct turnstile *ts; 1106 1107 /* 1108 * Follow the chain. We keep walking as long as the thread is 1109 * blocked on a turnstile that has an owner. 1110 */ 1111 while (!db_pager_quit) { 1112 db_printf("%sthread %d (pid %d, %s) ", prefix, td->td_tid, 1113 td->td_proc->p_pid, td->td_name[0] != '\0' ? td->td_name : 1114 td->td_name); 1115 switch (td->td_state) { 1116 case TDS_INACTIVE: 1117 db_printf("is inactive\n"); 1118 return; 1119 case TDS_CAN_RUN: 1120 db_printf("can run\n"); 1121 return; 1122 case TDS_RUNQ: 1123 db_printf("is on a run queue\n"); 1124 return; 1125 case TDS_RUNNING: 1126 db_printf("running on CPU %d\n", td->td_oncpu); 1127 return; 1128 case TDS_INHIBITED: 1129 if (TD_ON_LOCK(td)) { 1130 ts = td->td_blocked; 1131 lock = ts->ts_lockobj; 1132 class = LOCK_CLASS(lock); 1133 db_printf("blocked on lock %p (%s) \"%s\"\n", 1134 lock, class->lc_name, lock->lo_name); 1135 if (ts->ts_owner == NULL) 1136 return; 1137 td = ts->ts_owner; 1138 break; 1139 } 1140 db_printf("inhibited\n"); 1141 return; 1142 default: 1143 db_printf("??? (%#x)\n", td->td_state); 1144 return; 1145 } 1146 } 1147 } 1148 1149 DB_SHOW_COMMAND(lockchain, db_show_lockchain) 1150 { 1151 struct thread *td; 1152 1153 /* Figure out which thread to start with. */ 1154 if (have_addr) 1155 td = db_lookup_thread(addr, TRUE); 1156 else 1157 td = kdb_thread; 1158 1159 print_lockchain(td, ""); 1160 } 1161 1162 DB_SHOW_ALL_COMMAND(chains, db_show_allchains) 1163 { 1164 struct thread *td; 1165 struct proc *p; 1166 int i; 1167 1168 i = 1; 1169 FOREACH_PROC_IN_SYSTEM(p) { 1170 FOREACH_THREAD_IN_PROC(p, td) { 1171 if (TD_ON_LOCK(td) && LIST_EMPTY(&td->td_contested)) { 1172 db_printf("chain %d:\n", i++); 1173 print_lockchain(td, " "); 1174 } 1175 if (db_pager_quit) 1176 return; 1177 } 1178 } 1179 } 1180 DB_SHOW_ALIAS(allchains, db_show_allchains) 1181 1182 /* 1183 * Show all the threads a particular thread is waiting on based on 1184 * sleepable locks. 1185 */ 1186 static void 1187 print_sleepchain(struct thread *td, const char *prefix) 1188 { 1189 struct thread *owner; 1190 1191 /* 1192 * Follow the chain. We keep walking as long as the thread is 1193 * blocked on a sleep lock that has an owner. 1194 */ 1195 while (!db_pager_quit) { 1196 db_printf("%sthread %d (pid %d, %s) ", prefix, td->td_tid, 1197 td->td_proc->p_pid, td->td_name[0] != '\0' ? td->td_name : 1198 td->td_name); 1199 switch (td->td_state) { 1200 case TDS_INACTIVE: 1201 db_printf("is inactive\n"); 1202 return; 1203 case TDS_CAN_RUN: 1204 db_printf("can run\n"); 1205 return; 1206 case TDS_RUNQ: 1207 db_printf("is on a run queue\n"); 1208 return; 1209 case TDS_RUNNING: 1210 db_printf("running on CPU %d\n", td->td_oncpu); 1211 return; 1212 case TDS_INHIBITED: 1213 if (TD_ON_SLEEPQ(td)) { 1214 if (lockmgr_chain(td, &owner) || 1215 sx_chain(td, &owner)) { 1216 if (owner == NULL) 1217 return; 1218 td = owner; 1219 break; 1220 } 1221 db_printf("sleeping on %p \"%s\"\n", 1222 td->td_wchan, td->td_wmesg); 1223 return; 1224 } 1225 db_printf("inhibited\n"); 1226 return; 1227 default: 1228 db_printf("??? (%#x)\n", td->td_state); 1229 return; 1230 } 1231 } 1232 } 1233 1234 DB_SHOW_COMMAND(sleepchain, db_show_sleepchain) 1235 { 1236 struct thread *td; 1237 1238 /* Figure out which thread to start with. */ 1239 if (have_addr) 1240 td = db_lookup_thread(addr, TRUE); 1241 else 1242 td = kdb_thread; 1243 1244 print_sleepchain(td, ""); 1245 } 1246 1247 static void print_waiters(struct turnstile *ts, int indent); 1248 1249 static void 1250 print_waiter(struct thread *td, int indent) 1251 { 1252 struct turnstile *ts; 1253 int i; 1254 1255 if (db_pager_quit) 1256 return; 1257 for (i = 0; i < indent; i++) 1258 db_printf(" "); 1259 print_thread(td, "thread "); 1260 LIST_FOREACH(ts, &td->td_contested, ts_link) 1261 print_waiters(ts, indent + 1); 1262 } 1263 1264 static void 1265 print_waiters(struct turnstile *ts, int indent) 1266 { 1267 struct lock_object *lock; 1268 struct lock_class *class; 1269 struct thread *td; 1270 int i; 1271 1272 if (db_pager_quit) 1273 return; 1274 lock = ts->ts_lockobj; 1275 class = LOCK_CLASS(lock); 1276 for (i = 0; i < indent; i++) 1277 db_printf(" "); 1278 db_printf("lock %p (%s) \"%s\"\n", lock, class->lc_name, lock->lo_name); 1279 TAILQ_FOREACH(td, &ts->ts_blocked[TS_EXCLUSIVE_QUEUE], td_lockq) 1280 print_waiter(td, indent + 1); 1281 TAILQ_FOREACH(td, &ts->ts_blocked[TS_SHARED_QUEUE], td_lockq) 1282 print_waiter(td, indent + 1); 1283 TAILQ_FOREACH(td, &ts->ts_pending, td_lockq) 1284 print_waiter(td, indent + 1); 1285 } 1286 1287 DB_SHOW_COMMAND(locktree, db_show_locktree) 1288 { 1289 struct lock_object *lock; 1290 struct lock_class *class; 1291 struct turnstile_chain *tc; 1292 struct turnstile *ts; 1293 1294 if (!have_addr) 1295 return; 1296 lock = (struct lock_object *)addr; 1297 tc = TC_LOOKUP(lock); 1298 LIST_FOREACH(ts, &tc->tc_turnstiles, ts_hash) 1299 if (ts->ts_lockobj == lock) 1300 break; 1301 if (ts == NULL) { 1302 class = LOCK_CLASS(lock); 1303 db_printf("lock %p (%s) \"%s\"\n", lock, class->lc_name, 1304 lock->lo_name); 1305 } else 1306 print_waiters(ts, 0); 1307 } 1308 #endif 1309