1/*- 2 * SPDX-License-Identifier: BSD-3-Clause 3 * 4 * Copyright (c) 1998 Berkeley Software Design, Inc. All rights reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 3. Berkeley Software Design Inc's name may not be used to endorse or 15 * promote products derived from this software without specific prior 16 * written permission. 17 * 18 * THIS SOFTWARE IS PROVIDED BY BERKELEY SOFTWARE DESIGN INC ``AS IS'' AND 19 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 20 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 21 * ARE DISCLAIMED. IN NO EVENT SHALL BERKELEY SOFTWARE DESIGN INC BE LIABLE 22 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 23 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 24 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 25 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 26 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 27 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 28 * SUCH DAMAGE. 29 * 30 * from BSDI $Id: mutex_witness.c,v 1.1.2.20 2000/04/27 03:10:27 cp Exp $ 31 * and BSDI $Id: synch_machdep.c,v 2.3.2.39 2000/04/27 03:10:25 cp Exp $ 32 */ 33 34/* 35 * Implementation of turnstiles used to hold queue of threads blocked on 36 * non-sleepable locks. Sleepable locks use condition variables to 37 * implement their queues. Turnstiles differ from a sleep queue in that 38 * turnstile queue's are assigned to a lock held by an owning thread. Thus, 39 * when one thread is enqueued onto a turnstile, it can lend its priority 40 * to the owning thread. 41 * 42 * We wish to avoid bloating locks with an embedded turnstile and we do not 43 * want to use back-pointers in the locks for the same reason. Thus, we 44 * use a similar approach to that of Solaris 7 as described in Solaris 45 * Internals by Jim Mauro and Richard McDougall. Turnstiles are looked up 46 * in a hash table based on the address of the lock. Each entry in the 47 * hash table is a linked-lists of turnstiles and is called a turnstile 48 * chain. Each chain contains a spin mutex that protects all of the 49 * turnstiles in the chain. 50 * 51 * Each time a thread is created, a turnstile is allocated from a UMA zone 52 * and attached to that thread. When a thread blocks on a lock, if it is the 53 * first thread to block, it lends its turnstile to the lock. If the lock 54 * already has a turnstile, then it gives its turnstile to the lock's 55 * turnstile's free list. When a thread is woken up, it takes a turnstile from 56 * the free list if there are any other waiters. If it is the only thread 57 * blocked on the lock, then it reclaims the turnstile associated with the lock 58 * and removes it from the hash table. 59 */ 60 61#include <sys/cdefs.h> 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/sdt.h> 77#include <sys/sysctl.h> 78#include <sys/turnstile.h> 79 80#include <vm/uma.h> 81 82#ifdef DDB 83#include <ddb/ddb.h> 84#include <sys/lockmgr.h> 85#include <sys/sx.h> 86#endif 87 88/* 89 * Constants for the hash table of turnstile chains. TC_SHIFT is a magic 90 * number chosen because the sleep queue's use the same value for the 91 * shift. Basically, we ignore the lower 8 bits of the address. 92 * TC_TABLESIZE must be a power of two for TC_MASK to work properly. 93 */ 94#define TC_TABLESIZE 128 /* Must be power of 2. */ 95#define TC_MASK (TC_TABLESIZE - 1) 96#define TC_SHIFT 8 97#define TC_HASH(lock) (((uintptr_t)(lock) >> TC_SHIFT) & TC_MASK) 98#define TC_LOOKUP(lock) &turnstile_chains[TC_HASH(lock)] 99 100/* 101 * There are three different lists of turnstiles as follows. The list 102 * connected by ts_link entries is a per-thread list of all the turnstiles 103 * attached to locks that we own. This is used to fixup our priority when 104 * a lock is released. The other two lists use the ts_hash entries. The 105 * first of these two is the turnstile chain list that a turnstile is on 106 * when it is attached to a lock. The second list to use ts_hash is the 107 * free list hung off of a turnstile that is attached to a lock. 108 * 109 * Each turnstile contains three lists of threads. The two ts_blocked lists 110 * are linked list of threads blocked on the turnstile's lock. One list is 111 * for exclusive waiters, and the other is for shared waiters. The 112 * ts_pending list is a linked list of threads previously awakened by 113 * turnstile_signal() or turnstile_wait() that are waiting to be put on 114 * the run queue. 115 * 116 * Locking key: 117 * c - turnstile chain lock 118 * q - td_contested lock 119 */ 120struct turnstile { 121 struct mtx ts_lock; /* Spin lock for self. */ 122 struct threadqueue ts_blocked[2]; /* (c + q) Blocked threads. */ 123 struct threadqueue ts_pending; /* (c) Pending threads. */ 124 LIST_ENTRY(turnstile) ts_hash; /* (c) Chain and free list. */ 125 LIST_ENTRY(turnstile) ts_link; /* (q) Contested locks. */ 126 LIST_HEAD(, turnstile) ts_free; /* (c) Free turnstiles. */ 127 struct lock_object *ts_lockobj; /* (c) Lock we reference. */ 128 struct thread *ts_owner; /* (c + q) Who owns the lock. */ 129}; 130 131struct turnstile_chain { 132 LIST_HEAD(, turnstile) tc_turnstiles; /* List of turnstiles. */ 133 struct mtx tc_lock; /* Spin lock for this chain. */ 134#ifdef TURNSTILE_PROFILING 135 u_int tc_depth; /* Length of tc_queues. */ 136 u_int tc_max_depth; /* Max length of tc_queues. */ 137#endif 138}; 139 140#ifdef TURNSTILE_PROFILING 141u_int turnstile_max_depth; 142static SYSCTL_NODE(_debug, OID_AUTO, turnstile, CTLFLAG_RD | CTLFLAG_MPSAFE, 0, 143 "turnstile profiling"); 144static SYSCTL_NODE(_debug_turnstile, OID_AUTO, chains, 145 CTLFLAG_RD | CTLFLAG_MPSAFE, 0, 146 "turnstile chain stats"); 147SYSCTL_UINT(_debug_turnstile, OID_AUTO, max_depth, CTLFLAG_RD, 148 &turnstile_max_depth, 0, "maximum depth achieved of a single chain"); 149#endif 150static struct mtx td_contested_lock; 151static struct turnstile_chain turnstile_chains[TC_TABLESIZE]; 152static uma_zone_t turnstile_zone; 153 154/* 155 * Prototypes for non-exported routines. 156 */ 157static void init_turnstile0(void *dummy); 158#ifdef TURNSTILE_PROFILING 159static void init_turnstile_profiling(void *arg); 160#endif 161static void propagate_priority(struct thread *td); 162static int turnstile_adjust_thread(struct turnstile *ts, 163 struct thread *td); 164static struct thread *turnstile_first_waiter(struct turnstile *ts); 165static void turnstile_setowner(struct turnstile *ts, struct thread *owner); 166#ifdef INVARIANTS 167static void turnstile_dtor(void *mem, int size, void *arg); 168#endif 169static int turnstile_init(void *mem, int size, int flags); 170static void turnstile_fini(void *mem, int size); 171 172SDT_PROVIDER_DECLARE(sched); 173SDT_PROBE_DEFINE(sched, , , sleep); 174SDT_PROBE_DEFINE2(sched, , , wakeup, "struct thread *", 175 "struct proc *"); 176 177static inline void 178propagate_unlock_ts(struct turnstile *top, struct turnstile *ts) 179{ 180 181 if (ts != top) 182 mtx_unlock_spin(&ts->ts_lock); 183} 184 185static inline void 186propagate_unlock_td(struct turnstile *top, struct thread *td) 187{ 188 189 if (td->td_lock != &top->ts_lock) 190 thread_unlock(td); 191} 192 193/* 194 * Walks the chain of turnstiles and their owners to propagate the priority 195 * of the thread being blocked to all the threads holding locks that have to 196 * release their locks before this thread can run again. 197 */ 198static void 199propagate_priority(struct thread *td) 200{ 201 struct turnstile *ts, *top; 202 int pri; 203 204 THREAD_LOCK_ASSERT(td, MA_OWNED); 205 pri = td->td_priority; 206 top = ts = td->td_blocked; 207 THREAD_LOCKPTR_ASSERT(td, &ts->ts_lock); 208 209 /* 210 * The original turnstile lock is held across the entire 211 * operation. We only ever lock down the chain so the lock 212 * order is constant. 213 */ 214 for (;;) { 215 td = ts->ts_owner; 216 217 if (td == NULL) { 218 /* 219 * This might be a read lock with no owner. There's 220 * not much we can do, so just bail. 221 */ 222 propagate_unlock_ts(top, ts); 223 return; 224 } 225 226 /* 227 * Wait for the thread lock to be stable and then only 228 * acquire if it is not the turnstile lock. 229 */ 230 thread_lock_block_wait(td); 231 if (td->td_lock != &ts->ts_lock) { 232 thread_lock_flags(td, MTX_DUPOK); 233 propagate_unlock_ts(top, ts); 234 } 235 MPASS(td->td_proc != NULL); 236 MPASS(td->td_proc->p_magic == P_MAGIC); 237 238 /* 239 * If the thread is asleep, then we are probably about 240 * to deadlock. To make debugging this easier, show 241 * backtrace of misbehaving thread and panic to not 242 * leave the kernel deadlocked. 243 */ 244 if (TD_IS_SLEEPING(td)) { 245 printf( 246 "Sleeping thread (tid %d, pid %d) owns a non-sleepable lock\n", 247 td->td_tid, td->td_proc->p_pid); 248 kdb_backtrace_thread(td); 249 panic("sleeping thread"); 250 } 251 252 /* 253 * If this thread already has higher priority than the 254 * thread that is being blocked, we are finished. 255 */ 256 if (td->td_priority <= pri) { 257 propagate_unlock_td(top, td); 258 return; 259 } 260 261 /* 262 * Bump this thread's priority. 263 */ 264 sched_lend_prio(td, pri); 265 266 /* 267 * If lock holder is actually running or on the run queue 268 * then we are done. 269 */ 270 if (TD_IS_RUNNING(td) || TD_ON_RUNQ(td)) { 271 MPASS(td->td_blocked == NULL); 272 propagate_unlock_td(top, td); 273 return; 274 } 275 276#ifndef SMP 277 /* 278 * For UP, we check to see if td is curthread (this shouldn't 279 * ever happen however as it would mean we are in a deadlock.) 280 */ 281 KASSERT(td != curthread, ("Deadlock detected")); 282#endif 283 284 /* 285 * If we aren't blocked on a lock, we should be. 286 */ 287 KASSERT(TD_ON_LOCK(td), ( 288 "thread %d(%s):%d holds %s but isn't blocked on a lock\n", 289 td->td_tid, td->td_name, TD_GET_STATE(td), 290 ts->ts_lockobj->lo_name)); 291 292 /* 293 * Pick up the lock that td is blocked on. 294 */ 295 ts = td->td_blocked; 296 MPASS(ts != NULL); 297 THREAD_LOCKPTR_ASSERT(td, &ts->ts_lock); 298 /* Resort td on the list if needed. */ 299 if (!turnstile_adjust_thread(ts, td)) { 300 propagate_unlock_ts(top, ts); 301 return; 302 } 303 /* The thread lock is released as ts lock above. */ 304 } 305} 306 307/* 308 * Adjust the thread's position on a turnstile after its priority has been 309 * changed. 310 */ 311static int 312turnstile_adjust_thread(struct turnstile *ts, struct thread *td) 313{ 314 struct thread *td1, *td2; 315 int queue; 316 317 THREAD_LOCK_ASSERT(td, MA_OWNED); 318 MPASS(TD_ON_LOCK(td)); 319 320 /* 321 * This thread may not be blocked on this turnstile anymore 322 * but instead might already be woken up on another CPU 323 * that is waiting on the thread lock in turnstile_unpend() to 324 * finish waking this thread up. We can detect this case 325 * by checking to see if this thread has been given a 326 * turnstile by either turnstile_signal() or 327 * turnstile_broadcast(). In this case, treat the thread as 328 * if it was already running. 329 */ 330 if (td->td_turnstile != NULL) 331 return (0); 332 333 /* 334 * Check if the thread needs to be moved on the blocked chain. 335 * It needs to be moved if either its priority is lower than 336 * the previous thread or higher than the next thread. 337 */ 338 THREAD_LOCKPTR_BLOCKED_ASSERT(td, &ts->ts_lock); 339 td1 = TAILQ_PREV(td, threadqueue, td_lockq); 340 td2 = TAILQ_NEXT(td, td_lockq); 341 if ((td1 != NULL && td->td_priority < td1->td_priority) || 342 (td2 != NULL && td->td_priority > td2->td_priority)) { 343 /* 344 * Remove thread from blocked chain and determine where 345 * it should be moved to. 346 */ 347 queue = td->td_tsqueue; 348 MPASS(queue == TS_EXCLUSIVE_QUEUE || queue == TS_SHARED_QUEUE); 349 mtx_lock_spin(&td_contested_lock); 350 TAILQ_REMOVE(&ts->ts_blocked[queue], td, td_lockq); 351 TAILQ_FOREACH(td1, &ts->ts_blocked[queue], td_lockq) { 352 MPASS(td1->td_proc->p_magic == P_MAGIC); 353 if (td1->td_priority > td->td_priority) 354 break; 355 } 356 357 if (td1 == NULL) 358 TAILQ_INSERT_TAIL(&ts->ts_blocked[queue], td, td_lockq); 359 else 360 TAILQ_INSERT_BEFORE(td1, td, td_lockq); 361 mtx_unlock_spin(&td_contested_lock); 362 if (td1 == NULL) 363 CTR3(KTR_LOCK, 364 "turnstile_adjust_thread: td %d put at tail on [%p] %s", 365 td->td_tid, ts->ts_lockobj, ts->ts_lockobj->lo_name); 366 else 367 CTR4(KTR_LOCK, 368 "turnstile_adjust_thread: td %d moved before %d on [%p] %s", 369 td->td_tid, td1->td_tid, ts->ts_lockobj, 370 ts->ts_lockobj->lo_name); 371 } 372 return (1); 373} 374 375/* 376 * Early initialization of turnstiles. This is not done via a SYSINIT() 377 * since this needs to be initialized very early when mutexes are first 378 * initialized. 379 */ 380void 381init_turnstiles(void) 382{ 383 int i; 384 385 for (i = 0; i < TC_TABLESIZE; i++) { 386 LIST_INIT(&turnstile_chains[i].tc_turnstiles); 387 mtx_init(&turnstile_chains[i].tc_lock, "turnstile chain", 388 NULL, MTX_SPIN); 389 } 390 mtx_init(&td_contested_lock, "td_contested", NULL, MTX_SPIN); 391 LIST_INIT(&thread0.td_contested); 392 thread0.td_turnstile = NULL; 393} 394 395#ifdef TURNSTILE_PROFILING 396static void 397init_turnstile_profiling(void *arg) 398{ 399 struct sysctl_oid *chain_oid; 400 char chain_name[10]; 401 int i; 402 403 for (i = 0; i < TC_TABLESIZE; i++) { 404 snprintf(chain_name, sizeof(chain_name), "%d", i); 405 chain_oid = SYSCTL_ADD_NODE(NULL, 406 SYSCTL_STATIC_CHILDREN(_debug_turnstile_chains), OID_AUTO, 407 chain_name, CTLFLAG_RD | CTLFLAG_MPSAFE, NULL, 408 "turnstile chain stats"); 409 SYSCTL_ADD_UINT(NULL, SYSCTL_CHILDREN(chain_oid), OID_AUTO, 410 "depth", CTLFLAG_RD, &turnstile_chains[i].tc_depth, 0, 411 NULL); 412 SYSCTL_ADD_UINT(NULL, SYSCTL_CHILDREN(chain_oid), OID_AUTO, 413 "max_depth", CTLFLAG_RD, &turnstile_chains[i].tc_max_depth, 414 0, NULL); 415 } 416} 417SYSINIT(turnstile_profiling, SI_SUB_LOCK, SI_ORDER_ANY, 418 init_turnstile_profiling, NULL); 419#endif 420 421static void 422init_turnstile0(void *dummy) 423{ 424 425 turnstile_zone = uma_zcreate("TURNSTILE", sizeof(struct turnstile), 426 NULL, 427#ifdef INVARIANTS 428 turnstile_dtor, 429#else 430 NULL, 431#endif 432 turnstile_init, turnstile_fini, UMA_ALIGN_CACHE, UMA_ZONE_NOFREE); 433 thread0.td_turnstile = turnstile_alloc(); 434} 435SYSINIT(turnstile0, SI_SUB_LOCK, SI_ORDER_ANY, init_turnstile0, NULL); 436 437/* 438 * Update a thread on the turnstile list after it's priority has been changed. 439 * The old priority is passed in as an argument. 440 */ 441void 442turnstile_adjust(struct thread *td, u_char oldpri) 443{ 444 struct turnstile *ts; 445 446 MPASS(TD_ON_LOCK(td)); 447 448 /* 449 * Pick up the lock that td is blocked on. 450 */ 451 ts = td->td_blocked; 452 MPASS(ts != NULL); 453 THREAD_LOCKPTR_BLOCKED_ASSERT(td, &ts->ts_lock); 454 mtx_assert(&ts->ts_lock, MA_OWNED); 455 456 /* Resort the turnstile on the list. */ 457 if (!turnstile_adjust_thread(ts, td)) 458 return; 459 /* 460 * If our priority was lowered and we are at the head of the 461 * turnstile, then propagate our new priority up the chain. 462 * Note that we currently don't try to revoke lent priorities 463 * when our priority goes up. 464 */ 465 MPASS(td->td_tsqueue == TS_EXCLUSIVE_QUEUE || 466 td->td_tsqueue == TS_SHARED_QUEUE); 467 if (td == TAILQ_FIRST(&ts->ts_blocked[td->td_tsqueue]) && 468 td->td_priority < oldpri) { 469 propagate_priority(td); 470 } 471} 472 473/* 474 * Set the owner of the lock this turnstile is attached to. 475 */ 476static void 477turnstile_setowner(struct turnstile *ts, struct thread *owner) 478{ 479 480 mtx_assert(&td_contested_lock, MA_OWNED); 481 MPASS(ts->ts_owner == NULL); 482 483 /* A shared lock might not have an owner. */ 484 if (owner == NULL) 485 return; 486 487 MPASS(owner->td_proc->p_magic == P_MAGIC); 488 ts->ts_owner = owner; 489 LIST_INSERT_HEAD(&owner->td_contested, ts, ts_link); 490} 491 492#ifdef INVARIANTS 493/* 494 * UMA zone item deallocator. 495 */ 496static void 497turnstile_dtor(void *mem, int size, void *arg) 498{ 499 struct turnstile *ts; 500 501 ts = mem; 502 MPASS(TAILQ_EMPTY(&ts->ts_blocked[TS_EXCLUSIVE_QUEUE])); 503 MPASS(TAILQ_EMPTY(&ts->ts_blocked[TS_SHARED_QUEUE])); 504 MPASS(TAILQ_EMPTY(&ts->ts_pending)); 505} 506#endif 507 508/* 509 * UMA zone item initializer. 510 */ 511static int 512turnstile_init(void *mem, int size, int flags) 513{ 514 struct turnstile *ts; 515 516 bzero(mem, size); 517 ts = mem; 518 TAILQ_INIT(&ts->ts_blocked[TS_EXCLUSIVE_QUEUE]); 519 TAILQ_INIT(&ts->ts_blocked[TS_SHARED_QUEUE]); 520 TAILQ_INIT(&ts->ts_pending); 521 LIST_INIT(&ts->ts_free); 522 mtx_init(&ts->ts_lock, "turnstile lock", NULL, MTX_SPIN); 523 return (0); 524} 525 526static void 527turnstile_fini(void *mem, int size) 528{ 529 struct turnstile *ts; 530 531 ts = mem; 532 mtx_destroy(&ts->ts_lock); 533} 534 535/* 536 * Get a turnstile for a new thread. 537 */ 538struct turnstile * 539turnstile_alloc(void) 540{ 541 542 return (uma_zalloc(turnstile_zone, M_WAITOK)); 543} 544 545/* 546 * Free a turnstile when a thread is destroyed. 547 */ 548void 549turnstile_free(struct turnstile *ts) 550{ 551 552 uma_zfree(turnstile_zone, ts); 553} 554 555/* 556 * Lock the turnstile chain associated with the specified lock. 557 */ 558void 559turnstile_chain_lock(struct lock_object *lock) 560{ 561 struct turnstile_chain *tc; 562 563 tc = TC_LOOKUP(lock); 564 mtx_lock_spin(&tc->tc_lock); 565} 566 567struct turnstile * 568turnstile_trywait(struct lock_object *lock) 569{ 570 struct turnstile_chain *tc; 571 struct turnstile *ts; 572 573 tc = TC_LOOKUP(lock); 574 mtx_lock_spin(&tc->tc_lock); 575 LIST_FOREACH(ts, &tc->tc_turnstiles, ts_hash) 576 if (ts->ts_lockobj == lock) { 577 mtx_lock_spin(&ts->ts_lock); 578 return (ts); 579 } 580 581 ts = curthread->td_turnstile; 582 MPASS(ts != NULL); 583 mtx_lock_spin(&ts->ts_lock); 584 KASSERT(ts->ts_lockobj == NULL, ("stale ts_lockobj pointer")); 585 ts->ts_lockobj = lock; 586 587 return (ts); 588} 589 590bool 591turnstile_lock(struct turnstile *ts, struct lock_object **lockp, 592 struct thread **tdp) 593{ 594 struct turnstile_chain *tc; 595 struct lock_object *lock; 596 597 if ((lock = ts->ts_lockobj) == NULL) 598 return (false); 599 tc = TC_LOOKUP(lock); 600 mtx_lock_spin(&tc->tc_lock); 601 mtx_lock_spin(&ts->ts_lock); 602 if (__predict_false(lock != ts->ts_lockobj)) { 603 mtx_unlock_spin(&tc->tc_lock); 604 mtx_unlock_spin(&ts->ts_lock); 605 return (false); 606 } 607 *lockp = lock; 608 *tdp = ts->ts_owner; 609 return (true); 610} 611 612void 613turnstile_unlock(struct turnstile *ts, struct lock_object *lock) 614{ 615 struct turnstile_chain *tc; 616 617 mtx_assert(&ts->ts_lock, MA_OWNED); 618 mtx_unlock_spin(&ts->ts_lock); 619 if (ts == curthread->td_turnstile) 620 ts->ts_lockobj = NULL; 621 tc = TC_LOOKUP(lock); 622 mtx_unlock_spin(&tc->tc_lock); 623} 624 625void 626turnstile_assert(struct turnstile *ts) 627{ 628 MPASS(ts->ts_lockobj == NULL); 629} 630 631void 632turnstile_cancel(struct turnstile *ts) 633{ 634 struct turnstile_chain *tc; 635 struct lock_object *lock; 636 637 mtx_assert(&ts->ts_lock, MA_OWNED); 638 639 mtx_unlock_spin(&ts->ts_lock); 640 lock = ts->ts_lockobj; 641 if (ts == curthread->td_turnstile) 642 ts->ts_lockobj = NULL; 643 tc = TC_LOOKUP(lock); 644 mtx_unlock_spin(&tc->tc_lock); 645} 646 647/* 648 * Look up the turnstile for a lock in the hash table locking the associated 649 * turnstile chain along the way. If no turnstile is found in the hash 650 * table, NULL is returned. 651 */ 652struct turnstile * 653turnstile_lookup(struct lock_object *lock) 654{ 655 struct turnstile_chain *tc; 656 struct turnstile *ts; 657 658 tc = TC_LOOKUP(lock); 659 mtx_assert(&tc->tc_lock, MA_OWNED); 660 LIST_FOREACH(ts, &tc->tc_turnstiles, ts_hash) 661 if (ts->ts_lockobj == lock) { 662 mtx_lock_spin(&ts->ts_lock); 663 return (ts); 664 } 665 return (NULL); 666} 667 668/* 669 * Unlock the turnstile chain associated with a given lock. 670 */ 671void 672turnstile_chain_unlock(struct lock_object *lock) 673{ 674 struct turnstile_chain *tc; 675 676 tc = TC_LOOKUP(lock); 677 mtx_unlock_spin(&tc->tc_lock); 678} 679 680/* 681 * Return a pointer to the thread waiting on this turnstile with the 682 * most important priority or NULL if the turnstile has no waiters. 683 */ 684static struct thread * 685turnstile_first_waiter(struct turnstile *ts) 686{ 687 struct thread *std, *xtd; 688 689 std = TAILQ_FIRST(&ts->ts_blocked[TS_SHARED_QUEUE]); 690 xtd = TAILQ_FIRST(&ts->ts_blocked[TS_EXCLUSIVE_QUEUE]); 691 if (xtd == NULL || (std != NULL && std->td_priority < xtd->td_priority)) 692 return (std); 693 return (xtd); 694} 695 696/* 697 * Take ownership of a turnstile and adjust the priority of the new 698 * owner appropriately. 699 */ 700void 701turnstile_claim(struct turnstile *ts) 702{ 703 struct thread *td, *owner; 704 struct turnstile_chain *tc; 705 706 mtx_assert(&ts->ts_lock, MA_OWNED); 707 MPASS(ts != curthread->td_turnstile); 708 709 owner = curthread; 710 mtx_lock_spin(&td_contested_lock); 711 turnstile_setowner(ts, owner); 712 mtx_unlock_spin(&td_contested_lock); 713 714 td = turnstile_first_waiter(ts); 715 MPASS(td != NULL); 716 MPASS(td->td_proc->p_magic == P_MAGIC); 717 THREAD_LOCKPTR_BLOCKED_ASSERT(td, &ts->ts_lock); 718 719 /* 720 * Update the priority of the new owner if needed. 721 */ 722 thread_lock(owner); 723 if (td->td_priority < owner->td_priority) 724 sched_lend_prio(owner, td->td_priority); 725 thread_unlock(owner); 726 tc = TC_LOOKUP(ts->ts_lockobj); 727 mtx_unlock_spin(&ts->ts_lock); 728 mtx_unlock_spin(&tc->tc_lock); 729} 730 731/* 732 * Block the current thread on the turnstile assicated with 'lock'. This 733 * function will context switch and not return until this thread has been 734 * woken back up. This function must be called with the appropriate 735 * turnstile chain locked and will return with it unlocked. 736 */ 737void 738turnstile_wait(struct turnstile *ts, struct thread *owner, int queue) 739{ 740 struct turnstile_chain *tc; 741 struct thread *td, *td1; 742 struct lock_object *lock; 743 744 td = curthread; 745 mtx_assert(&ts->ts_lock, MA_OWNED); 746 if (owner) 747 MPASS(owner->td_proc->p_magic == P_MAGIC); 748 MPASS(queue == TS_SHARED_QUEUE || queue == TS_EXCLUSIVE_QUEUE); 749 750 /* 751 * If the lock does not already have a turnstile, use this thread's 752 * turnstile. Otherwise insert the current thread into the 753 * turnstile already in use by this lock. 754 */ 755 tc = TC_LOOKUP(ts->ts_lockobj); 756 mtx_assert(&tc->tc_lock, MA_OWNED); 757 if (ts == td->td_turnstile) { 758#ifdef TURNSTILE_PROFILING 759 tc->tc_depth++; 760 if (tc->tc_depth > tc->tc_max_depth) { 761 tc->tc_max_depth = tc->tc_depth; 762 if (tc->tc_max_depth > turnstile_max_depth) 763 turnstile_max_depth = tc->tc_max_depth; 764 } 765#endif 766 LIST_INSERT_HEAD(&tc->tc_turnstiles, ts, ts_hash); 767 KASSERT(TAILQ_EMPTY(&ts->ts_pending), 768 ("thread's turnstile has pending threads")); 769 KASSERT(TAILQ_EMPTY(&ts->ts_blocked[TS_EXCLUSIVE_QUEUE]), 770 ("thread's turnstile has exclusive waiters")); 771 KASSERT(TAILQ_EMPTY(&ts->ts_blocked[TS_SHARED_QUEUE]), 772 ("thread's turnstile has shared waiters")); 773 KASSERT(LIST_EMPTY(&ts->ts_free), 774 ("thread's turnstile has a non-empty free list")); 775 MPASS(ts->ts_lockobj != NULL); 776 mtx_lock_spin(&td_contested_lock); 777 TAILQ_INSERT_TAIL(&ts->ts_blocked[queue], td, td_lockq); 778 turnstile_setowner(ts, owner); 779 mtx_unlock_spin(&td_contested_lock); 780 } else { 781 TAILQ_FOREACH(td1, &ts->ts_blocked[queue], td_lockq) 782 if (td1->td_priority > td->td_priority) 783 break; 784 mtx_lock_spin(&td_contested_lock); 785 if (td1 != NULL) 786 TAILQ_INSERT_BEFORE(td1, td, td_lockq); 787 else 788 TAILQ_INSERT_TAIL(&ts->ts_blocked[queue], td, td_lockq); 789 MPASS(owner == ts->ts_owner); 790 mtx_unlock_spin(&td_contested_lock); 791 MPASS(td->td_turnstile != NULL); 792 LIST_INSERT_HEAD(&ts->ts_free, td->td_turnstile, ts_hash); 793 } 794 thread_lock(td); 795 thread_lock_set(td, &ts->ts_lock); 796 td->td_turnstile = NULL; 797 798 /* Save who we are blocked on and switch. */ 799 lock = ts->ts_lockobj; 800 td->td_tsqueue = queue; 801 td->td_blocked = ts; 802 td->td_lockname = lock->lo_name; 803 td->td_blktick = ticks; 804 TD_SET_LOCK(td); 805 mtx_unlock_spin(&tc->tc_lock); 806 propagate_priority(td); 807 808 if (LOCK_LOG_TEST(lock, 0)) 809 CTR4(KTR_LOCK, "%s: td %d blocked on [%p] %s", __func__, 810 td->td_tid, lock, lock->lo_name); 811 812 SDT_PROBE0(sched, , , sleep); 813 814 THREAD_LOCKPTR_ASSERT(td, &ts->ts_lock); 815 mi_switch(SW_VOL | SWT_TURNSTILE); 816 817 if (LOCK_LOG_TEST(lock, 0)) 818 CTR4(KTR_LOCK, "%s: td %d free from blocked on [%p] %s", 819 __func__, td->td_tid, lock, lock->lo_name); 820} 821 822/* 823 * Pick the highest priority thread on this turnstile and put it on the 824 * pending list. This must be called with the turnstile chain locked. 825 */ 826int 827turnstile_signal(struct turnstile *ts, int queue) 828{ 829 struct turnstile_chain *tc __unused; 830 struct thread *td; 831 int empty; 832 833 MPASS(ts != NULL); 834 mtx_assert(&ts->ts_lock, MA_OWNED); 835 MPASS(curthread->td_proc->p_magic == P_MAGIC); 836 MPASS(ts->ts_owner == curthread || ts->ts_owner == NULL); 837 MPASS(queue == TS_SHARED_QUEUE || queue == TS_EXCLUSIVE_QUEUE); 838 839 /* 840 * Pick the highest priority thread blocked on this lock and 841 * move it to the pending list. 842 */ 843 td = TAILQ_FIRST(&ts->ts_blocked[queue]); 844 MPASS(td->td_proc->p_magic == P_MAGIC); 845 mtx_lock_spin(&td_contested_lock); 846 TAILQ_REMOVE(&ts->ts_blocked[queue], td, td_lockq); 847 mtx_unlock_spin(&td_contested_lock); 848 TAILQ_INSERT_TAIL(&ts->ts_pending, td, td_lockq); 849 850 /* 851 * If the turnstile is now empty, remove it from its chain and 852 * give it to the about-to-be-woken thread. Otherwise take a 853 * turnstile from the free list and give it to the thread. 854 */ 855 empty = TAILQ_EMPTY(&ts->ts_blocked[TS_EXCLUSIVE_QUEUE]) && 856 TAILQ_EMPTY(&ts->ts_blocked[TS_SHARED_QUEUE]); 857 if (empty) { 858 tc = TC_LOOKUP(ts->ts_lockobj); 859 mtx_assert(&tc->tc_lock, MA_OWNED); 860 MPASS(LIST_EMPTY(&ts->ts_free)); 861#ifdef TURNSTILE_PROFILING 862 tc->tc_depth--; 863#endif 864 } else 865 ts = LIST_FIRST(&ts->ts_free); 866 MPASS(ts != NULL); 867 LIST_REMOVE(ts, ts_hash); 868 td->td_turnstile = ts; 869 870 return (empty); 871} 872 873/* 874 * Put all blocked threads on the pending list. This must be called with 875 * the turnstile chain locked. 876 */ 877void 878turnstile_broadcast(struct turnstile *ts, int queue) 879{ 880 struct turnstile_chain *tc __unused; 881 struct turnstile *ts1; 882 struct thread *td; 883 884 MPASS(ts != NULL); 885 mtx_assert(&ts->ts_lock, MA_OWNED); 886 MPASS(curthread->td_proc->p_magic == P_MAGIC); 887 MPASS(ts->ts_owner == curthread || ts->ts_owner == NULL); 888 /* 889 * We must have the chain locked so that we can remove the empty 890 * turnstile from the hash queue. 891 */ 892 tc = TC_LOOKUP(ts->ts_lockobj); 893 mtx_assert(&tc->tc_lock, MA_OWNED); 894 MPASS(queue == TS_SHARED_QUEUE || queue == TS_EXCLUSIVE_QUEUE); 895 896 /* 897 * Transfer the blocked list to the pending list. 898 */ 899 mtx_lock_spin(&td_contested_lock); 900 TAILQ_CONCAT(&ts->ts_pending, &ts->ts_blocked[queue], td_lockq); 901 mtx_unlock_spin(&td_contested_lock); 902 903 /* 904 * Give a turnstile to each thread. The last thread gets 905 * this turnstile if the turnstile is empty. 906 */ 907 TAILQ_FOREACH(td, &ts->ts_pending, td_lockq) { 908 if (LIST_EMPTY(&ts->ts_free)) { 909 MPASS(TAILQ_NEXT(td, td_lockq) == NULL); 910 ts1 = ts; 911#ifdef TURNSTILE_PROFILING 912 tc->tc_depth--; 913#endif 914 } else 915 ts1 = LIST_FIRST(&ts->ts_free); 916 MPASS(ts1 != NULL); 917 LIST_REMOVE(ts1, ts_hash); 918 td->td_turnstile = ts1; 919 } 920} 921 922static u_char 923turnstile_calc_unlend_prio_locked(struct thread *td) 924{ 925 struct turnstile *nts; 926 u_char cp, pri; 927 928 THREAD_LOCK_ASSERT(td, MA_OWNED); 929 mtx_assert(&td_contested_lock, MA_OWNED); 930 931 pri = PRI_MAX; 932 LIST_FOREACH(nts, &td->td_contested, ts_link) { 933 cp = turnstile_first_waiter(nts)->td_priority; 934 if (cp < pri) 935 pri = cp; 936 } 937 return (pri); 938} 939 940/* 941 * Wakeup all threads on the pending list and adjust the priority of the 942 * current thread appropriately. This must be called with the turnstile 943 * chain locked. 944 */ 945void 946turnstile_unpend(struct turnstile *ts) 947{ 948 TAILQ_HEAD( ,thread) pending_threads; 949 struct thread *td; 950 u_char pri; 951 952 MPASS(ts != NULL); 953 mtx_assert(&ts->ts_lock, MA_OWNED); 954 MPASS(ts->ts_owner == curthread || ts->ts_owner == NULL); 955 MPASS(!TAILQ_EMPTY(&ts->ts_pending)); 956 957 /* 958 * Move the list of pending threads out of the turnstile and 959 * into a local variable. 960 */ 961 TAILQ_INIT(&pending_threads); 962 TAILQ_CONCAT(&pending_threads, &ts->ts_pending, td_lockq); 963#ifdef INVARIANTS 964 if (TAILQ_EMPTY(&ts->ts_blocked[TS_EXCLUSIVE_QUEUE]) && 965 TAILQ_EMPTY(&ts->ts_blocked[TS_SHARED_QUEUE])) 966 ts->ts_lockobj = NULL; 967#endif 968 /* 969 * Adjust the priority of curthread based on other contested 970 * locks it owns. Don't lower the priority below the base 971 * priority however. 972 */ 973 td = curthread; 974 thread_lock(td); 975 mtx_lock_spin(&td_contested_lock); 976 /* 977 * Remove the turnstile from this thread's list of contested locks 978 * since this thread doesn't own it anymore. New threads will 979 * not be blocking on the turnstile until it is claimed by a new 980 * owner. There might not be a current owner if this is a shared 981 * lock. 982 */ 983 if (ts->ts_owner != NULL) { 984 ts->ts_owner = NULL; 985 LIST_REMOVE(ts, ts_link); 986 } 987 pri = turnstile_calc_unlend_prio_locked(td); 988 mtx_unlock_spin(&td_contested_lock); 989 sched_unlend_prio(td, pri); 990 thread_unlock(td); 991 /* 992 * Wake up all the pending threads. If a thread is not blocked 993 * on a lock, then it is currently executing on another CPU in 994 * turnstile_wait() or sitting on a run queue waiting to resume 995 * in turnstile_wait(). Set a flag to force it to try to acquire 996 * the lock again instead of blocking. 997 */ 998 while (!TAILQ_EMPTY(&pending_threads)) { 999 td = TAILQ_FIRST(&pending_threads); 1000 TAILQ_REMOVE(&pending_threads, td, td_lockq); 1001 SDT_PROBE2(sched, , , wakeup, td, td->td_proc); 1002 thread_lock_block_wait(td); 1003 THREAD_LOCKPTR_ASSERT(td, &ts->ts_lock); 1004 MPASS(td->td_proc->p_magic == P_MAGIC); 1005 MPASS(TD_ON_LOCK(td)); 1006 TD_CLR_LOCK(td); 1007 MPASS(TD_CAN_RUN(td)); 1008 td->td_blocked = NULL; 1009 td->td_lockname = NULL; 1010 td->td_blktick = 0; 1011#ifdef INVARIANTS 1012 td->td_tsqueue = 0xff; 1013#endif 1014 sched_add(td, SRQ_HOLD | SRQ_BORING); 1015 } 1016 mtx_unlock_spin(&ts->ts_lock); 1017} 1018 1019/* 1020 * Give up ownership of a turnstile. This must be called with the 1021 * turnstile chain locked. 1022 */ 1023void 1024turnstile_disown(struct turnstile *ts) 1025{ 1026 struct thread *td; 1027 u_char pri; 1028 1029 MPASS(ts != NULL); 1030 mtx_assert(&ts->ts_lock, MA_OWNED); 1031 MPASS(ts->ts_owner == curthread); 1032 MPASS(TAILQ_EMPTY(&ts->ts_pending)); 1033 MPASS(!TAILQ_EMPTY(&ts->ts_blocked[TS_EXCLUSIVE_QUEUE]) || 1034 !TAILQ_EMPTY(&ts->ts_blocked[TS_SHARED_QUEUE])); 1035 1036 /* 1037 * Remove the turnstile from this thread's list of contested locks 1038 * since this thread doesn't own it anymore. New threads will 1039 * not be blocking on the turnstile until it is claimed by a new 1040 * owner. 1041 */ 1042 mtx_lock_spin(&td_contested_lock); 1043 ts->ts_owner = NULL; 1044 LIST_REMOVE(ts, ts_link); 1045 mtx_unlock_spin(&td_contested_lock); 1046 1047 /* 1048 * Adjust the priority of curthread based on other contested 1049 * locks it owns. Don't lower the priority below the base 1050 * priority however. 1051 */ 1052 td = curthread; 1053 thread_lock(td); 1054 mtx_unlock_spin(&ts->ts_lock); 1055 mtx_lock_spin(&td_contested_lock); 1056 pri = turnstile_calc_unlend_prio_locked(td); 1057 mtx_unlock_spin(&td_contested_lock); 1058 sched_unlend_prio(td, pri); 1059 thread_unlock(td); 1060} 1061 1062/* 1063 * Return the first thread in a turnstile. 1064 */ 1065struct thread * 1066turnstile_head(struct turnstile *ts, int queue) 1067{ 1068#ifdef INVARIANTS 1069 1070 MPASS(ts != NULL); 1071 MPASS(queue == TS_SHARED_QUEUE || queue == TS_EXCLUSIVE_QUEUE); 1072 mtx_assert(&ts->ts_lock, MA_OWNED); 1073#endif 1074 return (TAILQ_FIRST(&ts->ts_blocked[queue])); 1075} 1076 1077/* 1078 * Returns true if a sub-queue of a turnstile is empty. 1079 */ 1080int 1081turnstile_empty(struct turnstile *ts, int queue) 1082{ 1083#ifdef INVARIANTS 1084 1085 MPASS(ts != NULL); 1086 MPASS(queue == TS_SHARED_QUEUE || queue == TS_EXCLUSIVE_QUEUE); 1087 mtx_assert(&ts->ts_lock, MA_OWNED); 1088#endif 1089 return (TAILQ_EMPTY(&ts->ts_blocked[queue])); 1090} 1091 1092#ifdef DDB 1093static void 1094print_thread(struct thread *td, const char *prefix) 1095{ 1096 1097 db_printf("%s%p (tid %d, pid %d, \"%s\")\n", prefix, td, td->td_tid, 1098 td->td_proc->p_pid, td->td_name); 1099} 1100 1101static void 1102print_queue(struct threadqueue *queue, const char *header, const char *prefix) 1103{ 1104 struct thread *td; 1105 1106 db_printf("%s:\n", header); 1107 if (TAILQ_EMPTY(queue)) { 1108 db_printf("%sempty\n", prefix); 1109 return; 1110 } 1111 TAILQ_FOREACH(td, queue, td_lockq) { 1112 print_thread(td, prefix); 1113 } 1114} 1115 1116DB_SHOW_COMMAND(turnstile, db_show_turnstile) 1117{ 1118 struct turnstile_chain *tc; 1119 struct turnstile *ts; 1120 struct lock_object *lock; 1121 int i; 1122 1123 if (!have_addr) 1124 return; 1125 1126 /* 1127 * First, see if there is an active turnstile for the lock indicated 1128 * by the address. 1129 */ 1130 lock = (struct lock_object *)addr; 1131 tc = TC_LOOKUP(lock); 1132 LIST_FOREACH(ts, &tc->tc_turnstiles, ts_hash) 1133 if (ts->ts_lockobj == lock) 1134 goto found; 1135 1136 /* 1137 * Second, see if there is an active turnstile at the address 1138 * indicated. 1139 */ 1140 for (i = 0; i < TC_TABLESIZE; i++) 1141 LIST_FOREACH(ts, &turnstile_chains[i].tc_turnstiles, ts_hash) { 1142 if (ts == (struct turnstile *)addr) 1143 goto found; 1144 } 1145 1146 db_printf("Unable to locate a turnstile via %p\n", (void *)addr); 1147 return; 1148found: 1149 lock = ts->ts_lockobj; 1150 db_printf("Lock: %p - (%s) %s\n", lock, LOCK_CLASS(lock)->lc_name, 1151 lock->lo_name); 1152 if (ts->ts_owner) 1153 print_thread(ts->ts_owner, "Lock Owner: "); 1154 else 1155 db_printf("Lock Owner: none\n"); 1156 print_queue(&ts->ts_blocked[TS_SHARED_QUEUE], "Shared Waiters", "\t"); 1157 print_queue(&ts->ts_blocked[TS_EXCLUSIVE_QUEUE], "Exclusive Waiters", 1158 "\t"); 1159 print_queue(&ts->ts_pending, "Pending Threads", "\t"); 1160 1161} 1162 1163/* 1164 * Show all the threads a particular thread is waiting on based on 1165 * non-spin locks. 1166 */ 1167static void 1168print_lockchain(struct thread *td, const char *prefix) 1169{ 1170 struct lock_object *lock; 1171 struct lock_class *class; 1172 struct turnstile *ts; 1173 struct thread *owner; 1174 1175 /* 1176 * Follow the chain. We keep walking as long as the thread is 1177 * blocked on a lock that has an owner. 1178 */ 1179 while (!db_pager_quit) { 1180 if (td == (void *)LK_KERNPROC) { 1181 db_printf("%sdisowned (LK_KERNPROC)\n", prefix); 1182 return; 1183 } 1184 db_printf("%sthread %d (pid %d, %s) is ", prefix, td->td_tid, 1185 td->td_proc->p_pid, td->td_name); 1186 switch (TD_GET_STATE(td)) { 1187 case TDS_INACTIVE: 1188 db_printf("inactive\n"); 1189 return; 1190 case TDS_CAN_RUN: 1191 db_printf("runnable\n"); 1192 return; 1193 case TDS_RUNQ: 1194 db_printf("on a run queue\n"); 1195 return; 1196 case TDS_RUNNING: 1197 db_printf("running on CPU %d\n", td->td_oncpu); 1198 return; 1199 case TDS_INHIBITED: 1200 if (TD_ON_LOCK(td)) { 1201 ts = td->td_blocked; 1202 lock = ts->ts_lockobj; 1203 class = LOCK_CLASS(lock); 1204 db_printf("blocked on lock %p (%s) \"%s\"\n", 1205 lock, class->lc_name, lock->lo_name); 1206 if (ts->ts_owner == NULL) 1207 return; 1208 td = ts->ts_owner; 1209 break; 1210 } else if (TD_ON_SLEEPQ(td)) { 1211 if (!lockmgr_chain(td, &owner) && 1212 !sx_chain(td, &owner)) { 1213 db_printf("sleeping on %p \"%s\"\n", 1214 td->td_wchan, td->td_wmesg); 1215 return; 1216 } 1217 if (owner == NULL) 1218 return; 1219 td = owner; 1220 break; 1221 } 1222 db_printf("inhibited: %s\n", KTDSTATE(td)); 1223 return; 1224 default: 1225 db_printf("??? (%#x)\n", TD_GET_STATE(td)); 1226 return; 1227 } 1228 } 1229} 1230 1231DB_SHOW_COMMAND(lockchain, db_show_lockchain) 1232{ 1233 struct thread *td; 1234 1235 /* Figure out which thread to start with. */ 1236 if (have_addr) 1237 td = db_lookup_thread(addr, true); 1238 else 1239 td = kdb_thread; 1240 1241 print_lockchain(td, ""); 1242} 1243DB_SHOW_ALIAS(sleepchain, db_show_lockchain); 1244 1245DB_SHOW_ALL_COMMAND(chains, db_show_allchains) 1246{ 1247 struct thread *td; 1248 struct proc *p; 1249 int i; 1250 1251 i = 1; 1252 FOREACH_PROC_IN_SYSTEM(p) { 1253 FOREACH_THREAD_IN_PROC(p, td) { 1254 if ((TD_ON_LOCK(td) && LIST_EMPTY(&td->td_contested)) 1255 || (TD_IS_INHIBITED(td) && TD_ON_SLEEPQ(td))) { 1256 db_printf("chain %d:\n", i++); 1257 print_lockchain(td, " "); 1258 } 1259 if (db_pager_quit) 1260 return; 1261 } 1262 } 1263} 1264DB_SHOW_ALIAS_FLAGS(allchains, db_show_allchains, DB_CMD_MEMSAFE); 1265 1266static void print_waiters(struct turnstile *ts, int indent); 1267 1268static void 1269print_waiter(struct thread *td, int indent) 1270{ 1271 struct turnstile *ts; 1272 int i; 1273 1274 if (db_pager_quit) 1275 return; 1276 for (i = 0; i < indent; i++) 1277 db_printf(" "); 1278 print_thread(td, "thread "); 1279 LIST_FOREACH(ts, &td->td_contested, ts_link) 1280 print_waiters(ts, indent + 1); 1281} 1282 1283static void 1284print_waiters(struct turnstile *ts, int indent) 1285{ 1286 struct lock_object *lock; 1287 struct lock_class *class; 1288 struct thread *td; 1289 int i; 1290 1291 if (db_pager_quit) 1292 return; 1293 lock = ts->ts_lockobj; 1294 class = LOCK_CLASS(lock); 1295 for (i = 0; i < indent; i++) 1296 db_printf(" "); 1297 db_printf("lock %p (%s) \"%s\"\n", lock, class->lc_name, lock->lo_name); 1298 TAILQ_FOREACH(td, &ts->ts_blocked[TS_EXCLUSIVE_QUEUE], td_lockq) 1299 print_waiter(td, indent + 1); 1300 TAILQ_FOREACH(td, &ts->ts_blocked[TS_SHARED_QUEUE], td_lockq) 1301 print_waiter(td, indent + 1); 1302 TAILQ_FOREACH(td, &ts->ts_pending, td_lockq) 1303 print_waiter(td, indent + 1); 1304} 1305 1306DB_SHOW_COMMAND(locktree, db_show_locktree) 1307{ 1308 struct lock_object *lock; 1309 struct lock_class *class; 1310 struct turnstile_chain *tc; 1311 struct turnstile *ts; 1312 1313 if (!have_addr) 1314 return; 1315 lock = (struct lock_object *)addr; 1316 tc = TC_LOOKUP(lock); 1317 LIST_FOREACH(ts, &tc->tc_turnstiles, ts_hash) 1318 if (ts->ts_lockobj == lock) 1319 break; 1320 if (ts == NULL) { 1321 class = LOCK_CLASS(lock); 1322 db_printf("lock %p (%s) \"%s\"\n", lock, class->lc_name, 1323 lock->lo_name); 1324 } else 1325 print_waiters(ts, 0); 1326} 1327#endif 1328