subr_turnstile.c revision 234303
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: head/sys/kern/subr_turnstile.c 234303 2012-04-14 23:59:58Z davide $"); 61 62#include "opt_ddb.h" 63#include "opt_turnstile_profiling.h" 64#include "opt_sched.h" 65 66#include <sys/param.h> 67#include <sys/systm.h> 68#include <sys/kdb.h> 69#include <sys/kernel.h> 70#include <sys/ktr.h> 71#include <sys/lock.h> 72#include <sys/mutex.h> 73#include <sys/proc.h> 74#include <sys/queue.h> 75#include <sys/sched.h> 76#include <sys/sysctl.h> 77#include <sys/turnstile.h> 78 79#include <vm/uma.h> 80 81#ifdef DDB 82#include <ddb/ddb.h> 83#include <sys/lockmgr.h> 84#include <sys/sx.h> 85#endif 86 87/* 88 * Constants for the hash table of turnstile chains. TC_SHIFT is a magic 89 * number chosen because the sleep queue's use the same value for the 90 * shift. Basically, we ignore the lower 8 bits of the address. 91 * TC_TABLESIZE must be a power of two for TC_MASK to work properly. 92 */ 93#define TC_TABLESIZE 128 /* Must be power of 2. */ 94#define TC_MASK (TC_TABLESIZE - 1) 95#define TC_SHIFT 8 96#define TC_HASH(lock) (((uintptr_t)(lock) >> TC_SHIFT) & TC_MASK) 97#define TC_LOOKUP(lock) &turnstile_chains[TC_HASH(lock)] 98 99/* 100 * There are three different lists of turnstiles as follows. The list 101 * connected by ts_link entries is a per-thread list of all the turnstiles 102 * attached to locks that we own. This is used to fixup our priority when 103 * a lock is released. The other two lists use the ts_hash entries. The 104 * first of these two is the turnstile chain list that a turnstile is on 105 * when it is attached to a lock. The second list to use ts_hash is the 106 * free list hung off of a turnstile that is attached to a lock. 107 * 108 * Each turnstile contains three lists of threads. The two ts_blocked lists 109 * are linked list of threads blocked on the turnstile's lock. One list is 110 * for exclusive waiters, and the other is for shared waiters. The 111 * ts_pending list is a linked list of threads previously awakened by 112 * turnstile_signal() or turnstile_wait() that are waiting to be put on 113 * the run queue. 114 * 115 * Locking key: 116 * c - turnstile chain lock 117 * q - td_contested lock 118 */ 119struct turnstile { 120 struct mtx ts_lock; /* Spin lock for self. */ 121 struct threadqueue ts_blocked[2]; /* (c + q) Blocked threads. */ 122 struct threadqueue ts_pending; /* (c) Pending threads. */ 123 LIST_ENTRY(turnstile) ts_hash; /* (c) Chain and free list. */ 124 LIST_ENTRY(turnstile) ts_link; /* (q) Contested locks. */ 125 LIST_HEAD(, turnstile) ts_free; /* (c) Free turnstiles. */ 126 struct lock_object *ts_lockobj; /* (c) Lock we reference. */ 127 struct thread *ts_owner; /* (c + q) Who owns the lock. */ 128}; 129 130struct turnstile_chain { 131 LIST_HEAD(, turnstile) tc_turnstiles; /* List of turnstiles. */ 132 struct mtx tc_lock; /* Spin lock for this chain. */ 133#ifdef TURNSTILE_PROFILING 134 u_int tc_depth; /* Length of tc_queues. */ 135 u_int tc_max_depth; /* Max length of tc_queues. */ 136#endif 137}; 138 139#ifdef TURNSTILE_PROFILING 140u_int turnstile_max_depth; 141static SYSCTL_NODE(_debug, OID_AUTO, turnstile, CTLFLAG_RD, 0, 142 "turnstile profiling"); 143static SYSCTL_NODE(_debug_turnstile, OID_AUTO, chains, CTLFLAG_RD, 0, 144 "turnstile chain stats"); 145SYSCTL_UINT(_debug_turnstile, OID_AUTO, max_depth, CTLFLAG_RD, 146 &turnstile_max_depth, 0, "maximum depth achieved of a single chain"); 147#endif 148static struct mtx td_contested_lock; 149static struct turnstile_chain turnstile_chains[TC_TABLESIZE]; 150static uma_zone_t turnstile_zone; 151 152/* 153 * Prototypes for non-exported routines. 154 */ 155static void init_turnstile0(void *dummy); 156#ifdef TURNSTILE_PROFILING 157static void init_turnstile_profiling(void *arg); 158#endif 159static void propagate_priority(struct thread *td); 160static int turnstile_adjust_thread(struct turnstile *ts, 161 struct thread *td); 162static struct thread *turnstile_first_waiter(struct turnstile *ts); 163static void turnstile_setowner(struct turnstile *ts, struct thread *owner); 164#ifdef INVARIANTS 165static void turnstile_dtor(void *mem, int size, void *arg); 166#endif 167static int turnstile_init(void *mem, int size, int flags); 168static void turnstile_fini(void *mem, int size); 169 170/* 171 * Walks the chain of turnstiles and their owners to propagate the priority 172 * of the thread being blocked to all the threads holding locks that have to 173 * release their locks before this thread can run again. 174 */ 175static void 176propagate_priority(struct thread *td) 177{ 178 struct turnstile *ts; 179 int pri; 180 181 THREAD_LOCK_ASSERT(td, MA_OWNED); 182 pri = td->td_priority; 183 ts = td->td_blocked; 184 THREAD_LOCKPTR_ASSERT(td, &ts->ts_lock); 185 /* 186 * Grab a recursive lock on this turnstile chain so it stays locked 187 * for the whole operation. The caller expects us to return with 188 * the original lock held. We only ever lock down the chain so 189 * the lock order is constant. 190 */ 191 mtx_lock_spin(&ts->ts_lock); 192 for (;;) { 193 td = ts->ts_owner; 194 195 if (td == NULL) { 196 /* 197 * This might be a read lock with no owner. There's 198 * not much we can do, so just bail. 199 */ 200 mtx_unlock_spin(&ts->ts_lock); 201 return; 202 } 203 204 thread_lock_flags(td, MTX_DUPOK); 205 mtx_unlock_spin(&ts->ts_lock); 206 MPASS(td->td_proc != NULL); 207 MPASS(td->td_proc->p_magic == P_MAGIC); 208 209 /* 210 * If the thread is asleep, then we are probably about 211 * to deadlock. To make debugging this easier, just 212 * panic and tell the user which thread misbehaved so 213 * they can hopefully get a stack trace from the truly 214 * misbehaving thread. 215 */ 216 if (TD_IS_SLEEPING(td)) { 217 printf( 218 "Sleeping thread (tid %d, pid %d) owns a non-sleepable lock\n", 219 td->td_tid, td->td_proc->p_pid); 220 kdb_backtrace_thread(td); 221 panic("sleeping thread"); 222 } 223 224 /* 225 * If this thread already has higher priority than the 226 * thread that is being blocked, we are finished. 227 */ 228 if (td->td_priority <= pri) { 229 thread_unlock(td); 230 return; 231 } 232 233 /* 234 * Bump this thread's priority. 235 */ 236 sched_lend_prio(td, pri); 237 238 /* 239 * If lock holder is actually running or on the run queue 240 * then we are done. 241 */ 242 if (TD_IS_RUNNING(td) || TD_ON_RUNQ(td)) { 243 MPASS(td->td_blocked == NULL); 244 thread_unlock(td); 245 return; 246 } 247 248#ifndef SMP 249 /* 250 * For UP, we check to see if td is curthread (this shouldn't 251 * ever happen however as it would mean we are in a deadlock.) 252 */ 253 KASSERT(td != curthread, ("Deadlock detected")); 254#endif 255 256 /* 257 * If we aren't blocked on a lock, we should be. 258 */ 259 KASSERT(TD_ON_LOCK(td), ( 260 "thread %d(%s):%d holds %s but isn't blocked on a lock\n", 261 td->td_tid, td->td_name, td->td_state, 262 ts->ts_lockobj->lo_name)); 263 264 /* 265 * Pick up the lock that td is blocked on. 266 */ 267 ts = td->td_blocked; 268 MPASS(ts != NULL); 269 THREAD_LOCKPTR_ASSERT(td, &ts->ts_lock); 270 /* Resort td on the list if needed. */ 271 if (!turnstile_adjust_thread(ts, td)) { 272 mtx_unlock_spin(&ts->ts_lock); 273 return; 274 } 275 /* The thread lock is released as ts lock above. */ 276 } 277} 278 279/* 280 * Adjust the thread's position on a turnstile after its priority has been 281 * changed. 282 */ 283static int 284turnstile_adjust_thread(struct turnstile *ts, struct thread *td) 285{ 286 struct thread *td1, *td2; 287 int queue; 288 289 THREAD_LOCK_ASSERT(td, MA_OWNED); 290 MPASS(TD_ON_LOCK(td)); 291 292 /* 293 * This thread may not be blocked on this turnstile anymore 294 * but instead might already be woken up on another CPU 295 * that is waiting on the thread lock in turnstile_unpend() to 296 * finish waking this thread up. We can detect this case 297 * by checking to see if this thread has been given a 298 * turnstile by either turnstile_signal() or 299 * turnstile_broadcast(). In this case, treat the thread as 300 * if it was already running. 301 */ 302 if (td->td_turnstile != NULL) 303 return (0); 304 305 /* 306 * Check if the thread needs to be moved on the blocked chain. 307 * It needs to be moved if either its priority is lower than 308 * the previous thread or higher than the next thread. 309 */ 310 THREAD_LOCKPTR_ASSERT(td, &ts->ts_lock); 311 td1 = TAILQ_PREV(td, threadqueue, td_lockq); 312 td2 = TAILQ_NEXT(td, td_lockq); 313 if ((td1 != NULL && td->td_priority < td1->td_priority) || 314 (td2 != NULL && td->td_priority > td2->td_priority)) { 315 316 /* 317 * Remove thread from blocked chain and determine where 318 * it should be moved to. 319 */ 320 queue = td->td_tsqueue; 321 MPASS(queue == TS_EXCLUSIVE_QUEUE || queue == TS_SHARED_QUEUE); 322 mtx_lock_spin(&td_contested_lock); 323 TAILQ_REMOVE(&ts->ts_blocked[queue], td, td_lockq); 324 TAILQ_FOREACH(td1, &ts->ts_blocked[queue], td_lockq) { 325 MPASS(td1->td_proc->p_magic == P_MAGIC); 326 if (td1->td_priority > td->td_priority) 327 break; 328 } 329 330 if (td1 == NULL) 331 TAILQ_INSERT_TAIL(&ts->ts_blocked[queue], td, td_lockq); 332 else 333 TAILQ_INSERT_BEFORE(td1, td, td_lockq); 334 mtx_unlock_spin(&td_contested_lock); 335 if (td1 == NULL) 336 CTR3(KTR_LOCK, 337 "turnstile_adjust_thread: td %d put at tail on [%p] %s", 338 td->td_tid, ts->ts_lockobj, ts->ts_lockobj->lo_name); 339 else 340 CTR4(KTR_LOCK, 341 "turnstile_adjust_thread: td %d moved before %d on [%p] %s", 342 td->td_tid, td1->td_tid, ts->ts_lockobj, 343 ts->ts_lockobj->lo_name); 344 } 345 return (1); 346} 347 348/* 349 * Early initialization of turnstiles. This is not done via a SYSINIT() 350 * since this needs to be initialized very early when mutexes are first 351 * initialized. 352 */ 353void 354init_turnstiles(void) 355{ 356 int i; 357 358 for (i = 0; i < TC_TABLESIZE; i++) { 359 LIST_INIT(&turnstile_chains[i].tc_turnstiles); 360 mtx_init(&turnstile_chains[i].tc_lock, "turnstile chain", 361 NULL, MTX_SPIN); 362 } 363 mtx_init(&td_contested_lock, "td_contested", NULL, MTX_SPIN); 364 LIST_INIT(&thread0.td_contested); 365 thread0.td_turnstile = NULL; 366} 367 368#ifdef TURNSTILE_PROFILING 369static void 370init_turnstile_profiling(void *arg) 371{ 372 struct sysctl_oid *chain_oid; 373 char chain_name[10]; 374 int i; 375 376 for (i = 0; i < TC_TABLESIZE; i++) { 377 snprintf(chain_name, sizeof(chain_name), "%d", i); 378 chain_oid = SYSCTL_ADD_NODE(NULL, 379 SYSCTL_STATIC_CHILDREN(_debug_turnstile_chains), OID_AUTO, 380 chain_name, CTLFLAG_RD, NULL, "turnstile chain stats"); 381 SYSCTL_ADD_UINT(NULL, SYSCTL_CHILDREN(chain_oid), OID_AUTO, 382 "depth", CTLFLAG_RD, &turnstile_chains[i].tc_depth, 0, 383 NULL); 384 SYSCTL_ADD_UINT(NULL, SYSCTL_CHILDREN(chain_oid), OID_AUTO, 385 "max_depth", CTLFLAG_RD, &turnstile_chains[i].tc_max_depth, 386 0, NULL); 387 } 388} 389SYSINIT(turnstile_profiling, SI_SUB_LOCK, SI_ORDER_ANY, 390 init_turnstile_profiling, NULL); 391#endif 392 393static void 394init_turnstile0(void *dummy) 395{ 396 397 turnstile_zone = uma_zcreate("TURNSTILE", sizeof(struct turnstile), 398 NULL, 399#ifdef INVARIANTS 400 turnstile_dtor, 401#else 402 NULL, 403#endif 404 turnstile_init, turnstile_fini, UMA_ALIGN_CACHE, UMA_ZONE_NOFREE); 405 thread0.td_turnstile = turnstile_alloc(); 406} 407SYSINIT(turnstile0, SI_SUB_LOCK, SI_ORDER_ANY, init_turnstile0, NULL); 408 409/* 410 * Update a thread on the turnstile list after it's priority has been changed. 411 * The old priority is passed in as an argument. 412 */ 413void 414turnstile_adjust(struct thread *td, u_char oldpri) 415{ 416 struct turnstile *ts; 417 418 MPASS(TD_ON_LOCK(td)); 419 420 /* 421 * Pick up the lock that td is blocked on. 422 */ 423 ts = td->td_blocked; 424 MPASS(ts != NULL); 425 THREAD_LOCKPTR_ASSERT(td, &ts->ts_lock); 426 mtx_assert(&ts->ts_lock, MA_OWNED); 427 428 /* Resort the turnstile on the list. */ 429 if (!turnstile_adjust_thread(ts, td)) 430 return; 431 /* 432 * If our priority was lowered and we are at the head of the 433 * turnstile, then propagate our new priority up the chain. 434 * Note that we currently don't try to revoke lent priorities 435 * when our priority goes up. 436 */ 437 MPASS(td->td_tsqueue == TS_EXCLUSIVE_QUEUE || 438 td->td_tsqueue == TS_SHARED_QUEUE); 439 if (td == TAILQ_FIRST(&ts->ts_blocked[td->td_tsqueue]) && 440 td->td_priority < oldpri) { 441 propagate_priority(td); 442 } 443} 444 445/* 446 * Set the owner of the lock this turnstile is attached to. 447 */ 448static void 449turnstile_setowner(struct turnstile *ts, struct thread *owner) 450{ 451 452 mtx_assert(&td_contested_lock, MA_OWNED); 453 MPASS(ts->ts_owner == NULL); 454 455 /* A shared lock might not have an owner. */ 456 if (owner == NULL) 457 return; 458 459 MPASS(owner->td_proc->p_magic == P_MAGIC); 460 ts->ts_owner = owner; 461 LIST_INSERT_HEAD(&owner->td_contested, ts, ts_link); 462} 463 464#ifdef INVARIANTS 465/* 466 * UMA zone item deallocator. 467 */ 468static void 469turnstile_dtor(void *mem, int size, void *arg) 470{ 471 struct turnstile *ts; 472 473 ts = mem; 474 MPASS(TAILQ_EMPTY(&ts->ts_blocked[TS_EXCLUSIVE_QUEUE])); 475 MPASS(TAILQ_EMPTY(&ts->ts_blocked[TS_SHARED_QUEUE])); 476 MPASS(TAILQ_EMPTY(&ts->ts_pending)); 477} 478#endif 479 480/* 481 * UMA zone item initializer. 482 */ 483static int 484turnstile_init(void *mem, int size, int flags) 485{ 486 struct turnstile *ts; 487 488 bzero(mem, size); 489 ts = mem; 490 TAILQ_INIT(&ts->ts_blocked[TS_EXCLUSIVE_QUEUE]); 491 TAILQ_INIT(&ts->ts_blocked[TS_SHARED_QUEUE]); 492 TAILQ_INIT(&ts->ts_pending); 493 LIST_INIT(&ts->ts_free); 494 mtx_init(&ts->ts_lock, "turnstile lock", NULL, MTX_SPIN | MTX_RECURSE); 495 return (0); 496} 497 498static void 499turnstile_fini(void *mem, int size) 500{ 501 struct turnstile *ts; 502 503 ts = mem; 504 mtx_destroy(&ts->ts_lock); 505} 506 507/* 508 * Get a turnstile for a new thread. 509 */ 510struct turnstile * 511turnstile_alloc(void) 512{ 513 514 return (uma_zalloc(turnstile_zone, M_WAITOK)); 515} 516 517/* 518 * Free a turnstile when a thread is destroyed. 519 */ 520void 521turnstile_free(struct turnstile *ts) 522{ 523 524 uma_zfree(turnstile_zone, ts); 525} 526 527/* 528 * Lock the turnstile chain associated with the specified lock. 529 */ 530void 531turnstile_chain_lock(struct lock_object *lock) 532{ 533 struct turnstile_chain *tc; 534 535 tc = TC_LOOKUP(lock); 536 mtx_lock_spin(&tc->tc_lock); 537} 538 539struct turnstile * 540turnstile_trywait(struct lock_object *lock) 541{ 542 struct turnstile_chain *tc; 543 struct turnstile *ts; 544 545 tc = TC_LOOKUP(lock); 546 mtx_lock_spin(&tc->tc_lock); 547 LIST_FOREACH(ts, &tc->tc_turnstiles, ts_hash) 548 if (ts->ts_lockobj == lock) { 549 mtx_lock_spin(&ts->ts_lock); 550 return (ts); 551 } 552 553 ts = curthread->td_turnstile; 554 MPASS(ts != NULL); 555 mtx_lock_spin(&ts->ts_lock); 556 KASSERT(ts->ts_lockobj == NULL, ("stale ts_lockobj pointer")); 557 ts->ts_lockobj = lock; 558 559 return (ts); 560} 561 562void 563turnstile_cancel(struct turnstile *ts) 564{ 565 struct turnstile_chain *tc; 566 struct lock_object *lock; 567 568 mtx_assert(&ts->ts_lock, MA_OWNED); 569 570 mtx_unlock_spin(&ts->ts_lock); 571 lock = ts->ts_lockobj; 572 if (ts == curthread->td_turnstile) 573 ts->ts_lockobj = NULL; 574 tc = TC_LOOKUP(lock); 575 mtx_unlock_spin(&tc->tc_lock); 576} 577 578/* 579 * Look up the turnstile for a lock in the hash table locking the associated 580 * turnstile chain along the way. If no turnstile is found in the hash 581 * table, NULL is returned. 582 */ 583struct turnstile * 584turnstile_lookup(struct lock_object *lock) 585{ 586 struct turnstile_chain *tc; 587 struct turnstile *ts; 588 589 tc = TC_LOOKUP(lock); 590 mtx_assert(&tc->tc_lock, MA_OWNED); 591 LIST_FOREACH(ts, &tc->tc_turnstiles, ts_hash) 592 if (ts->ts_lockobj == lock) { 593 mtx_lock_spin(&ts->ts_lock); 594 return (ts); 595 } 596 return (NULL); 597} 598 599/* 600 * Unlock the turnstile chain associated with a given lock. 601 */ 602void 603turnstile_chain_unlock(struct lock_object *lock) 604{ 605 struct turnstile_chain *tc; 606 607 tc = TC_LOOKUP(lock); 608 mtx_unlock_spin(&tc->tc_lock); 609} 610 611/* 612 * Return a pointer to the thread waiting on this turnstile with the 613 * most important priority or NULL if the turnstile has no waiters. 614 */ 615static struct thread * 616turnstile_first_waiter(struct turnstile *ts) 617{ 618 struct thread *std, *xtd; 619 620 std = TAILQ_FIRST(&ts->ts_blocked[TS_SHARED_QUEUE]); 621 xtd = TAILQ_FIRST(&ts->ts_blocked[TS_EXCLUSIVE_QUEUE]); 622 if (xtd == NULL || (std != NULL && std->td_priority < xtd->td_priority)) 623 return (std); 624 return (xtd); 625} 626 627/* 628 * Take ownership of a turnstile and adjust the priority of the new 629 * owner appropriately. 630 */ 631void 632turnstile_claim(struct turnstile *ts) 633{ 634 struct thread *td, *owner; 635 struct turnstile_chain *tc; 636 637 mtx_assert(&ts->ts_lock, MA_OWNED); 638 MPASS(ts != curthread->td_turnstile); 639 640 owner = curthread; 641 mtx_lock_spin(&td_contested_lock); 642 turnstile_setowner(ts, owner); 643 mtx_unlock_spin(&td_contested_lock); 644 645 td = turnstile_first_waiter(ts); 646 MPASS(td != NULL); 647 MPASS(td->td_proc->p_magic == P_MAGIC); 648 THREAD_LOCKPTR_ASSERT(td, &ts->ts_lock); 649 650 /* 651 * Update the priority of the new owner if needed. 652 */ 653 thread_lock(owner); 654 if (td->td_priority < owner->td_priority) 655 sched_lend_prio(owner, td->td_priority); 656 thread_unlock(owner); 657 tc = TC_LOOKUP(ts->ts_lockobj); 658 mtx_unlock_spin(&ts->ts_lock); 659 mtx_unlock_spin(&tc->tc_lock); 660} 661 662/* 663 * Block the current thread on the turnstile assicated with 'lock'. This 664 * function will context switch and not return until this thread has been 665 * woken back up. This function must be called with the appropriate 666 * turnstile chain locked and will return with it unlocked. 667 */ 668void 669turnstile_wait(struct turnstile *ts, struct thread *owner, int queue) 670{ 671 struct turnstile_chain *tc; 672 struct thread *td, *td1; 673 struct lock_object *lock; 674 675 td = curthread; 676 mtx_assert(&ts->ts_lock, MA_OWNED); 677 if (owner) 678 MPASS(owner->td_proc->p_magic == P_MAGIC); 679 MPASS(queue == TS_SHARED_QUEUE || queue == TS_EXCLUSIVE_QUEUE); 680 681 /* 682 * If the lock does not already have a turnstile, use this thread's 683 * turnstile. Otherwise insert the current thread into the 684 * turnstile already in use by this lock. 685 */ 686 tc = TC_LOOKUP(ts->ts_lockobj); 687 mtx_assert(&tc->tc_lock, MA_OWNED); 688 if (ts == td->td_turnstile) { 689#ifdef TURNSTILE_PROFILING 690 tc->tc_depth++; 691 if (tc->tc_depth > tc->tc_max_depth) { 692 tc->tc_max_depth = tc->tc_depth; 693 if (tc->tc_max_depth > turnstile_max_depth) 694 turnstile_max_depth = tc->tc_max_depth; 695 } 696#endif 697 LIST_INSERT_HEAD(&tc->tc_turnstiles, ts, ts_hash); 698 KASSERT(TAILQ_EMPTY(&ts->ts_pending), 699 ("thread's turnstile has pending threads")); 700 KASSERT(TAILQ_EMPTY(&ts->ts_blocked[TS_EXCLUSIVE_QUEUE]), 701 ("thread's turnstile has exclusive waiters")); 702 KASSERT(TAILQ_EMPTY(&ts->ts_blocked[TS_SHARED_QUEUE]), 703 ("thread's turnstile has shared waiters")); 704 KASSERT(LIST_EMPTY(&ts->ts_free), 705 ("thread's turnstile has a non-empty free list")); 706 MPASS(ts->ts_lockobj != NULL); 707 mtx_lock_spin(&td_contested_lock); 708 TAILQ_INSERT_TAIL(&ts->ts_blocked[queue], td, td_lockq); 709 turnstile_setowner(ts, owner); 710 mtx_unlock_spin(&td_contested_lock); 711 } else { 712 TAILQ_FOREACH(td1, &ts->ts_blocked[queue], td_lockq) 713 if (td1->td_priority > td->td_priority) 714 break; 715 mtx_lock_spin(&td_contested_lock); 716 if (td1 != NULL) 717 TAILQ_INSERT_BEFORE(td1, td, td_lockq); 718 else 719 TAILQ_INSERT_TAIL(&ts->ts_blocked[queue], td, td_lockq); 720 MPASS(owner == ts->ts_owner); 721 mtx_unlock_spin(&td_contested_lock); 722 MPASS(td->td_turnstile != NULL); 723 LIST_INSERT_HEAD(&ts->ts_free, td->td_turnstile, ts_hash); 724 } 725 thread_lock(td); 726 thread_lock_set(td, &ts->ts_lock); 727 td->td_turnstile = NULL; 728 729 /* Save who we are blocked on and switch. */ 730 lock = ts->ts_lockobj; 731 td->td_tsqueue = queue; 732 td->td_blocked = ts; 733 td->td_lockname = lock->lo_name; 734 td->td_blktick = ticks; 735 TD_SET_LOCK(td); 736 mtx_unlock_spin(&tc->tc_lock); 737 propagate_priority(td); 738 739 if (LOCK_LOG_TEST(lock, 0)) 740 CTR4(KTR_LOCK, "%s: td %d blocked on [%p] %s", __func__, 741 td->td_tid, lock, lock->lo_name); 742 743 THREAD_LOCKPTR_ASSERT(td, &ts->ts_lock); 744 mi_switch(SW_VOL | SWT_TURNSTILE, NULL); 745 746 if (LOCK_LOG_TEST(lock, 0)) 747 CTR4(KTR_LOCK, "%s: td %d free from blocked on [%p] %s", 748 __func__, td->td_tid, lock, lock->lo_name); 749 thread_unlock(td); 750} 751 752/* 753 * Pick the highest priority thread on this turnstile and put it on the 754 * pending list. This must be called with the turnstile chain locked. 755 */ 756int 757turnstile_signal(struct turnstile *ts, int queue) 758{ 759 struct turnstile_chain *tc; 760 struct thread *td; 761 int empty; 762 763 MPASS(ts != NULL); 764 mtx_assert(&ts->ts_lock, MA_OWNED); 765 MPASS(curthread->td_proc->p_magic == P_MAGIC); 766 MPASS(ts->ts_owner == curthread || ts->ts_owner == NULL); 767 MPASS(queue == TS_SHARED_QUEUE || queue == TS_EXCLUSIVE_QUEUE); 768 769 /* 770 * Pick the highest priority thread blocked on this lock and 771 * move it to the pending list. 772 */ 773 td = TAILQ_FIRST(&ts->ts_blocked[queue]); 774 MPASS(td->td_proc->p_magic == P_MAGIC); 775 mtx_lock_spin(&td_contested_lock); 776 TAILQ_REMOVE(&ts->ts_blocked[queue], td, td_lockq); 777 mtx_unlock_spin(&td_contested_lock); 778 TAILQ_INSERT_TAIL(&ts->ts_pending, td, td_lockq); 779 780 /* 781 * If the turnstile is now empty, remove it from its chain and 782 * give it to the about-to-be-woken thread. Otherwise take a 783 * turnstile from the free list and give it to the thread. 784 */ 785 empty = TAILQ_EMPTY(&ts->ts_blocked[TS_EXCLUSIVE_QUEUE]) && 786 TAILQ_EMPTY(&ts->ts_blocked[TS_SHARED_QUEUE]); 787 if (empty) { 788 tc = TC_LOOKUP(ts->ts_lockobj); 789 mtx_assert(&tc->tc_lock, MA_OWNED); 790 MPASS(LIST_EMPTY(&ts->ts_free)); 791#ifdef TURNSTILE_PROFILING 792 tc->tc_depth--; 793#endif 794 } else 795 ts = LIST_FIRST(&ts->ts_free); 796 MPASS(ts != NULL); 797 LIST_REMOVE(ts, ts_hash); 798 td->td_turnstile = ts; 799 800 return (empty); 801} 802 803/* 804 * Put all blocked threads on the pending list. This must be called with 805 * the turnstile chain locked. 806 */ 807void 808turnstile_broadcast(struct turnstile *ts, int queue) 809{ 810 struct turnstile_chain *tc; 811 struct turnstile *ts1; 812 struct thread *td; 813 814 MPASS(ts != NULL); 815 mtx_assert(&ts->ts_lock, MA_OWNED); 816 MPASS(curthread->td_proc->p_magic == P_MAGIC); 817 MPASS(ts->ts_owner == curthread || ts->ts_owner == NULL); 818 /* 819 * We must have the chain locked so that we can remove the empty 820 * turnstile from the hash queue. 821 */ 822 tc = TC_LOOKUP(ts->ts_lockobj); 823 mtx_assert(&tc->tc_lock, MA_OWNED); 824 MPASS(queue == TS_SHARED_QUEUE || queue == TS_EXCLUSIVE_QUEUE); 825 826 /* 827 * Transfer the blocked list to the pending list. 828 */ 829 mtx_lock_spin(&td_contested_lock); 830 TAILQ_CONCAT(&ts->ts_pending, &ts->ts_blocked[queue], td_lockq); 831 mtx_unlock_spin(&td_contested_lock); 832 833 /* 834 * Give a turnstile to each thread. The last thread gets 835 * this turnstile if the turnstile is empty. 836 */ 837 TAILQ_FOREACH(td, &ts->ts_pending, td_lockq) { 838 if (LIST_EMPTY(&ts->ts_free)) { 839 MPASS(TAILQ_NEXT(td, td_lockq) == NULL); 840 ts1 = ts; 841#ifdef TURNSTILE_PROFILING 842 tc->tc_depth--; 843#endif 844 } else 845 ts1 = LIST_FIRST(&ts->ts_free); 846 MPASS(ts1 != NULL); 847 LIST_REMOVE(ts1, ts_hash); 848 td->td_turnstile = ts1; 849 } 850} 851 852/* 853 * Wakeup all threads on the pending list and adjust the priority of the 854 * current thread appropriately. This must be called with the turnstile 855 * chain locked. 856 */ 857void 858turnstile_unpend(struct turnstile *ts, int owner_type) 859{ 860 TAILQ_HEAD( ,thread) pending_threads; 861 struct turnstile *nts; 862 struct thread *td; 863 u_char cp, pri; 864 865 MPASS(ts != NULL); 866 mtx_assert(&ts->ts_lock, MA_OWNED); 867 MPASS(ts->ts_owner == curthread || ts->ts_owner == NULL); 868 MPASS(!TAILQ_EMPTY(&ts->ts_pending)); 869 870 /* 871 * Move the list of pending threads out of the turnstile and 872 * into a local variable. 873 */ 874 TAILQ_INIT(&pending_threads); 875 TAILQ_CONCAT(&pending_threads, &ts->ts_pending, td_lockq); 876#ifdef INVARIANTS 877 if (TAILQ_EMPTY(&ts->ts_blocked[TS_EXCLUSIVE_QUEUE]) && 878 TAILQ_EMPTY(&ts->ts_blocked[TS_SHARED_QUEUE])) 879 ts->ts_lockobj = NULL; 880#endif 881 /* 882 * Adjust the priority of curthread based on other contested 883 * locks it owns. Don't lower the priority below the base 884 * priority however. 885 */ 886 td = curthread; 887 pri = PRI_MAX; 888 thread_lock(td); 889 mtx_lock_spin(&td_contested_lock); 890 /* 891 * Remove the turnstile from this thread's list of contested locks 892 * since this thread doesn't own it anymore. New threads will 893 * not be blocking on the turnstile until it is claimed by a new 894 * owner. There might not be a current owner if this is a shared 895 * lock. 896 */ 897 if (ts->ts_owner != NULL) { 898 ts->ts_owner = NULL; 899 LIST_REMOVE(ts, ts_link); 900 } 901 LIST_FOREACH(nts, &td->td_contested, ts_link) { 902 cp = turnstile_first_waiter(nts)->td_priority; 903 if (cp < pri) 904 pri = cp; 905 } 906 mtx_unlock_spin(&td_contested_lock); 907 sched_unlend_prio(td, pri); 908 thread_unlock(td); 909 /* 910 * Wake up all the pending threads. If a thread is not blocked 911 * on a lock, then it is currently executing on another CPU in 912 * turnstile_wait() or sitting on a run queue waiting to resume 913 * in turnstile_wait(). Set a flag to force it to try to acquire 914 * the lock again instead of blocking. 915 */ 916 while (!TAILQ_EMPTY(&pending_threads)) { 917 td = TAILQ_FIRST(&pending_threads); 918 TAILQ_REMOVE(&pending_threads, td, td_lockq); 919 thread_lock(td); 920 THREAD_LOCKPTR_ASSERT(td, &ts->ts_lock); 921 MPASS(td->td_proc->p_magic == P_MAGIC); 922 MPASS(TD_ON_LOCK(td)); 923 TD_CLR_LOCK(td); 924 MPASS(TD_CAN_RUN(td)); 925 td->td_blocked = NULL; 926 td->td_lockname = NULL; 927 td->td_blktick = 0; 928#ifdef INVARIANTS 929 td->td_tsqueue = 0xff; 930#endif 931 sched_add(td, SRQ_BORING); 932 thread_unlock(td); 933 } 934 mtx_unlock_spin(&ts->ts_lock); 935} 936 937/* 938 * Give up ownership of a turnstile. This must be called with the 939 * turnstile chain locked. 940 */ 941void 942turnstile_disown(struct turnstile *ts) 943{ 944 struct thread *td; 945 u_char cp, pri; 946 947 MPASS(ts != NULL); 948 mtx_assert(&ts->ts_lock, MA_OWNED); 949 MPASS(ts->ts_owner == curthread); 950 MPASS(TAILQ_EMPTY(&ts->ts_pending)); 951 MPASS(!TAILQ_EMPTY(&ts->ts_blocked[TS_EXCLUSIVE_QUEUE]) || 952 !TAILQ_EMPTY(&ts->ts_blocked[TS_SHARED_QUEUE])); 953 954 /* 955 * Remove the turnstile from this thread's list of contested locks 956 * since this thread doesn't own it anymore. New threads will 957 * not be blocking on the turnstile until it is claimed by a new 958 * owner. 959 */ 960 mtx_lock_spin(&td_contested_lock); 961 ts->ts_owner = NULL; 962 LIST_REMOVE(ts, ts_link); 963 mtx_unlock_spin(&td_contested_lock); 964 965 /* 966 * Adjust the priority of curthread based on other contested 967 * locks it owns. Don't lower the priority below the base 968 * priority however. 969 */ 970 td = curthread; 971 pri = PRI_MAX; 972 thread_lock(td); 973 mtx_unlock_spin(&ts->ts_lock); 974 mtx_lock_spin(&td_contested_lock); 975 LIST_FOREACH(ts, &td->td_contested, ts_link) { 976 cp = turnstile_first_waiter(ts)->td_priority; 977 if (cp < pri) 978 pri = cp; 979 } 980 mtx_unlock_spin(&td_contested_lock); 981 sched_unlend_prio(td, pri); 982 thread_unlock(td); 983} 984 985/* 986 * Return the first thread in a turnstile. 987 */ 988struct thread * 989turnstile_head(struct turnstile *ts, int queue) 990{ 991#ifdef INVARIANTS 992 993 MPASS(ts != NULL); 994 MPASS(queue == TS_SHARED_QUEUE || queue == TS_EXCLUSIVE_QUEUE); 995 mtx_assert(&ts->ts_lock, MA_OWNED); 996#endif 997 return (TAILQ_FIRST(&ts->ts_blocked[queue])); 998} 999 1000/* 1001 * Returns true if a sub-queue of a turnstile is empty. 1002 */ 1003int 1004turnstile_empty(struct turnstile *ts, int queue) 1005{ 1006#ifdef INVARIANTS 1007 1008 MPASS(ts != NULL); 1009 MPASS(queue == TS_SHARED_QUEUE || queue == TS_EXCLUSIVE_QUEUE); 1010 mtx_assert(&ts->ts_lock, MA_OWNED); 1011#endif 1012 return (TAILQ_EMPTY(&ts->ts_blocked[queue])); 1013} 1014 1015#ifdef DDB 1016static void 1017print_thread(struct thread *td, const char *prefix) 1018{ 1019 1020 db_printf("%s%p (tid %d, pid %d, \"%s\")\n", prefix, td, td->td_tid, 1021 td->td_proc->p_pid, td->td_name[0] != '\0' ? td->td_name : 1022 td->td_name); 1023} 1024 1025static void 1026print_queue(struct threadqueue *queue, const char *header, const char *prefix) 1027{ 1028 struct thread *td; 1029 1030 db_printf("%s:\n", header); 1031 if (TAILQ_EMPTY(queue)) { 1032 db_printf("%sempty\n", prefix); 1033 return; 1034 } 1035 TAILQ_FOREACH(td, queue, td_lockq) { 1036 print_thread(td, prefix); 1037 } 1038} 1039 1040DB_SHOW_COMMAND(turnstile, db_show_turnstile) 1041{ 1042 struct turnstile_chain *tc; 1043 struct turnstile *ts; 1044 struct lock_object *lock; 1045 int i; 1046 1047 if (!have_addr) 1048 return; 1049 1050 /* 1051 * First, see if there is an active turnstile for the lock indicated 1052 * by the address. 1053 */ 1054 lock = (struct lock_object *)addr; 1055 tc = TC_LOOKUP(lock); 1056 LIST_FOREACH(ts, &tc->tc_turnstiles, ts_hash) 1057 if (ts->ts_lockobj == lock) 1058 goto found; 1059 1060 /* 1061 * Second, see if there is an active turnstile at the address 1062 * indicated. 1063 */ 1064 for (i = 0; i < TC_TABLESIZE; i++) 1065 LIST_FOREACH(ts, &turnstile_chains[i].tc_turnstiles, ts_hash) { 1066 if (ts == (struct turnstile *)addr) 1067 goto found; 1068 } 1069 1070 db_printf("Unable to locate a turnstile via %p\n", (void *)addr); 1071 return; 1072found: 1073 lock = ts->ts_lockobj; 1074 db_printf("Lock: %p - (%s) %s\n", lock, LOCK_CLASS(lock)->lc_name, 1075 lock->lo_name); 1076 if (ts->ts_owner) 1077 print_thread(ts->ts_owner, "Lock Owner: "); 1078 else 1079 db_printf("Lock Owner: none\n"); 1080 print_queue(&ts->ts_blocked[TS_SHARED_QUEUE], "Shared Waiters", "\t"); 1081 print_queue(&ts->ts_blocked[TS_EXCLUSIVE_QUEUE], "Exclusive Waiters", 1082 "\t"); 1083 print_queue(&ts->ts_pending, "Pending Threads", "\t"); 1084 1085} 1086 1087/* 1088 * Show all the threads a particular thread is waiting on based on 1089 * non-sleepable and non-spin locks. 1090 */ 1091static void 1092print_lockchain(struct thread *td, const char *prefix) 1093{ 1094 struct lock_object *lock; 1095 struct lock_class *class; 1096 struct turnstile *ts; 1097 1098 /* 1099 * Follow the chain. We keep walking as long as the thread is 1100 * blocked on a turnstile that has an owner. 1101 */ 1102 while (!db_pager_quit) { 1103 db_printf("%sthread %d (pid %d, %s) ", prefix, td->td_tid, 1104 td->td_proc->p_pid, td->td_name[0] != '\0' ? td->td_name : 1105 td->td_name); 1106 switch (td->td_state) { 1107 case TDS_INACTIVE: 1108 db_printf("is inactive\n"); 1109 return; 1110 case TDS_CAN_RUN: 1111 db_printf("can run\n"); 1112 return; 1113 case TDS_RUNQ: 1114 db_printf("is on a run queue\n"); 1115 return; 1116 case TDS_RUNNING: 1117 db_printf("running on CPU %d\n", td->td_oncpu); 1118 return; 1119 case TDS_INHIBITED: 1120 if (TD_ON_LOCK(td)) { 1121 ts = td->td_blocked; 1122 lock = ts->ts_lockobj; 1123 class = LOCK_CLASS(lock); 1124 db_printf("blocked on lock %p (%s) \"%s\"\n", 1125 lock, class->lc_name, lock->lo_name); 1126 if (ts->ts_owner == NULL) 1127 return; 1128 td = ts->ts_owner; 1129 break; 1130 } 1131 db_printf("inhibited\n"); 1132 return; 1133 default: 1134 db_printf("??? (%#x)\n", td->td_state); 1135 return; 1136 } 1137 } 1138} 1139 1140DB_SHOW_COMMAND(lockchain, db_show_lockchain) 1141{ 1142 struct thread *td; 1143 1144 /* Figure out which thread to start with. */ 1145 if (have_addr) 1146 td = db_lookup_thread(addr, TRUE); 1147 else 1148 td = kdb_thread; 1149 1150 print_lockchain(td, ""); 1151} 1152 1153DB_SHOW_ALL_COMMAND(chains, db_show_allchains) 1154{ 1155 struct thread *td; 1156 struct proc *p; 1157 int i; 1158 1159 i = 1; 1160 FOREACH_PROC_IN_SYSTEM(p) { 1161 FOREACH_THREAD_IN_PROC(p, td) { 1162 if (TD_ON_LOCK(td) && LIST_EMPTY(&td->td_contested)) { 1163 db_printf("chain %d:\n", i++); 1164 print_lockchain(td, " "); 1165 } 1166 if (db_pager_quit) 1167 return; 1168 } 1169 } 1170} 1171DB_SHOW_ALIAS(allchains, db_show_allchains) 1172 1173/* 1174 * Show all the threads a particular thread is waiting on based on 1175 * sleepable locks. 1176 */ 1177static void 1178print_sleepchain(struct thread *td, const char *prefix) 1179{ 1180 struct thread *owner; 1181 1182 /* 1183 * Follow the chain. We keep walking as long as the thread is 1184 * blocked on a sleep lock that has an owner. 1185 */ 1186 while (!db_pager_quit) { 1187 db_printf("%sthread %d (pid %d, %s) ", prefix, td->td_tid, 1188 td->td_proc->p_pid, td->td_name[0] != '\0' ? td->td_name : 1189 td->td_name); 1190 switch (td->td_state) { 1191 case TDS_INACTIVE: 1192 db_printf("is inactive\n"); 1193 return; 1194 case TDS_CAN_RUN: 1195 db_printf("can run\n"); 1196 return; 1197 case TDS_RUNQ: 1198 db_printf("is on a run queue\n"); 1199 return; 1200 case TDS_RUNNING: 1201 db_printf("running on CPU %d\n", td->td_oncpu); 1202 return; 1203 case TDS_INHIBITED: 1204 if (TD_ON_SLEEPQ(td)) { 1205 if (lockmgr_chain(td, &owner) || 1206 sx_chain(td, &owner)) { 1207 if (owner == NULL) 1208 return; 1209 td = owner; 1210 break; 1211 } 1212 db_printf("sleeping on %p \"%s\"\n", 1213 td->td_wchan, td->td_wmesg); 1214 return; 1215 } 1216 db_printf("inhibited\n"); 1217 return; 1218 default: 1219 db_printf("??? (%#x)\n", td->td_state); 1220 return; 1221 } 1222 } 1223} 1224 1225DB_SHOW_COMMAND(sleepchain, db_show_sleepchain) 1226{ 1227 struct thread *td; 1228 1229 /* Figure out which thread to start with. */ 1230 if (have_addr) 1231 td = db_lookup_thread(addr, TRUE); 1232 else 1233 td = kdb_thread; 1234 1235 print_sleepchain(td, ""); 1236} 1237 1238static void print_waiters(struct turnstile *ts, int indent); 1239 1240static void 1241print_waiter(struct thread *td, int indent) 1242{ 1243 struct turnstile *ts; 1244 int i; 1245 1246 if (db_pager_quit) 1247 return; 1248 for (i = 0; i < indent; i++) 1249 db_printf(" "); 1250 print_thread(td, "thread "); 1251 LIST_FOREACH(ts, &td->td_contested, ts_link) 1252 print_waiters(ts, indent + 1); 1253} 1254 1255static void 1256print_waiters(struct turnstile *ts, int indent) 1257{ 1258 struct lock_object *lock; 1259 struct lock_class *class; 1260 struct thread *td; 1261 int i; 1262 1263 if (db_pager_quit) 1264 return; 1265 lock = ts->ts_lockobj; 1266 class = LOCK_CLASS(lock); 1267 for (i = 0; i < indent; i++) 1268 db_printf(" "); 1269 db_printf("lock %p (%s) \"%s\"\n", lock, class->lc_name, lock->lo_name); 1270 TAILQ_FOREACH(td, &ts->ts_blocked[TS_EXCLUSIVE_QUEUE], td_lockq) 1271 print_waiter(td, indent + 1); 1272 TAILQ_FOREACH(td, &ts->ts_blocked[TS_SHARED_QUEUE], td_lockq) 1273 print_waiter(td, indent + 1); 1274 TAILQ_FOREACH(td, &ts->ts_pending, td_lockq) 1275 print_waiter(td, indent + 1); 1276} 1277 1278DB_SHOW_COMMAND(locktree, db_show_locktree) 1279{ 1280 struct lock_object *lock; 1281 struct lock_class *class; 1282 struct turnstile_chain *tc; 1283 struct turnstile *ts; 1284 1285 if (!have_addr) 1286 return; 1287 lock = (struct lock_object *)addr; 1288 tc = TC_LOOKUP(lock); 1289 LIST_FOREACH(ts, &tc->tc_turnstiles, ts_hash) 1290 if (ts->ts_lockobj == lock) 1291 break; 1292 if (ts == NULL) { 1293 class = LOCK_CLASS(lock); 1294 db_printf("lock %p (%s) \"%s\"\n", lock, class->lc_name, 1295 lock->lo_name); 1296 } else 1297 print_waiters(ts, 0); 1298} 1299#endif 1300