subr_witness.c revision 139348
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 the `witness' lock verifier. Originally implemented for 34 * mutexes in BSD/OS. Extended to handle generic lock objects and lock 35 * classes in FreeBSD. 36 */ 37 38/* 39 * Main Entry: witness 40 * Pronunciation: 'wit-n&s 41 * Function: noun 42 * Etymology: Middle English witnesse, from Old English witnes knowledge, 43 * testimony, witness, from 2wit 44 * Date: before 12th century 45 * 1 : attestation of a fact or event : TESTIMONY 46 * 2 : one that gives evidence; specifically : one who testifies in 47 * a cause or before a judicial tribunal 48 * 3 : one asked to be present at a transaction so as to be able to 49 * testify to its having taken place 50 * 4 : one who has personal knowledge of something 51 * 5 a : something serving as evidence or proof : SIGN 52 * b : public affirmation by word or example of usually 53 * religious faith or conviction <the heroic witness to divine 54 * life -- Pilot> 55 * 6 capitalized : a member of the Jehovah's Witnesses 56 */ 57 58/* 59 * Special rules concerning Giant and lock orders: 60 * 61 * 1) Giant must be acquired before any other mutexes. Stated another way, 62 * no other mutex may be held when Giant is acquired. 63 * 64 * 2) Giant must be released when blocking on a sleepable lock. 65 * 66 * This rule is less obvious, but is a result of Giant providing the same 67 * semantics as spl(). Basically, when a thread sleeps, it must release 68 * Giant. When a thread blocks on a sleepable lock, it sleeps. Hence rule 69 * 2). 70 * 71 * 3) Giant may be acquired before or after sleepable locks. 72 * 73 * This rule is also not quite as obvious. Giant may be acquired after 74 * a sleepable lock because it is a non-sleepable lock and non-sleepable 75 * locks may always be acquired while holding a sleepable lock. The second 76 * case, Giant before a sleepable lock, follows from rule 2) above. Suppose 77 * you have two threads T1 and T2 and a sleepable lock X. Suppose that T1 78 * acquires X and blocks on Giant. Then suppose that T2 acquires Giant and 79 * blocks on X. When T2 blocks on X, T2 will release Giant allowing T1 to 80 * execute. Thus, acquiring Giant both before and after a sleepable lock 81 * will not result in a lock order reversal. 82 */ 83 84#include <sys/cdefs.h> 85__FBSDID("$FreeBSD: head/sys/kern/subr_witness.c 139348 2004-12-27 10:47:08Z rwatson $"); 86 87#include "opt_ddb.h" 88#include "opt_witness.h" 89 90#include <sys/param.h> 91#include <sys/bus.h> 92#include <sys/kdb.h> 93#include <sys/kernel.h> 94#include <sys/ktr.h> 95#include <sys/lock.h> 96#include <sys/malloc.h> 97#include <sys/mutex.h> 98#include <sys/proc.h> 99#include <sys/sysctl.h> 100#include <sys/systm.h> 101 102#include <ddb/ddb.h> 103 104#include <machine/stdarg.h> 105 106/* Define this to check for blessed mutexes */ 107#undef BLESSING 108 109#define WITNESS_COUNT 200 110#define WITNESS_CHILDCOUNT (WITNESS_COUNT * 4) 111/* 112 * XXX: This is somewhat bogus, as we assume here that at most 1024 threads 113 * will hold LOCK_NCHILDREN * 2 locks. We handle failure ok, and we should 114 * probably be safe for the most part, but it's still a SWAG. 115 */ 116#define LOCK_CHILDCOUNT (MAXCPU + 1024) * 2 117 118#define WITNESS_NCHILDREN 6 119 120struct witness_child_list_entry; 121 122struct witness { 123 const char *w_name; 124 struct lock_class *w_class; 125 STAILQ_ENTRY(witness) w_list; /* List of all witnesses. */ 126 STAILQ_ENTRY(witness) w_typelist; /* Witnesses of a type. */ 127 struct witness_child_list_entry *w_children; /* Great evilness... */ 128 const char *w_file; 129 int w_line; 130 u_int w_level; 131 u_int w_refcount; 132 u_char w_Giant_squawked:1; 133 u_char w_other_squawked:1; 134 u_char w_same_squawked:1; 135 u_char w_displayed:1; 136}; 137 138struct witness_child_list_entry { 139 struct witness_child_list_entry *wcl_next; 140 struct witness *wcl_children[WITNESS_NCHILDREN]; 141 u_int wcl_count; 142}; 143 144STAILQ_HEAD(witness_list, witness); 145 146#ifdef BLESSING 147struct witness_blessed { 148 const char *b_lock1; 149 const char *b_lock2; 150}; 151#endif 152 153struct witness_order_list_entry { 154 const char *w_name; 155 struct lock_class *w_class; 156}; 157 158#ifdef BLESSING 159static int blessed(struct witness *, struct witness *); 160#endif 161static int depart(struct witness *w); 162static struct witness *enroll(const char *description, 163 struct lock_class *lock_class); 164static int insertchild(struct witness *parent, struct witness *child); 165static int isitmychild(struct witness *parent, struct witness *child); 166static int isitmydescendant(struct witness *parent, struct witness *child); 167static int itismychild(struct witness *parent, struct witness *child); 168static int rebalancetree(struct witness_list *list); 169static void removechild(struct witness *parent, struct witness *child); 170static int reparentchildren(struct witness *newparent, 171 struct witness *oldparent); 172static int sysctl_debug_witness_watch(SYSCTL_HANDLER_ARGS); 173static void witness_displaydescendants(void(*)(const char *fmt, ...), 174 struct witness *, int indent); 175static const char *fixup_filename(const char *file); 176static void witness_leveldescendents(struct witness *parent, int level); 177static void witness_levelall(void); 178static struct witness *witness_get(void); 179static void witness_free(struct witness *m); 180static struct witness_child_list_entry *witness_child_get(void); 181static void witness_child_free(struct witness_child_list_entry *wcl); 182static struct lock_list_entry *witness_lock_list_get(void); 183static void witness_lock_list_free(struct lock_list_entry *lle); 184static struct lock_instance *find_instance(struct lock_list_entry *lock_list, 185 struct lock_object *lock); 186static void witness_list_lock(struct lock_instance *instance); 187#ifdef DDB 188static void witness_list(struct thread *td); 189static void witness_display_list(void(*prnt)(const char *fmt, ...), 190 struct witness_list *list); 191static void witness_display(void(*)(const char *fmt, ...)); 192#endif 193 194MALLOC_DEFINE(M_WITNESS, "witness", "witness structure"); 195SYSCTL_NODE(_debug, OID_AUTO, witness, CTLFLAG_RW, 0, "Witness Locking"); 196 197/* 198 * If set to 0, witness is disabled. If set to 1, witness performs full lock 199 * order checking for all locks. If set to 2 or higher, then witness skips 200 * the full lock order check if the lock being acquired is at a higher level 201 * (i.e. farther down in the tree) than the current lock. This last mode is 202 * somewhat experimental and not considered fully safe. At runtime, this 203 * value may be set to 0 to turn off witness. witness is not allowed be 204 * turned on once it is turned off, however. 205 */ 206static int witness_watch = 1; 207TUNABLE_INT("debug.witness.watch", &witness_watch); 208SYSCTL_PROC(_debug_witness, OID_AUTO, watch, CTLFLAG_RW | CTLTYPE_INT, NULL, 0, 209 sysctl_debug_witness_watch, "I", "witness is watching lock operations"); 210 211#ifdef KDB 212/* 213 * When KDB is enabled and witness_kdb is set to 1, it will cause the system 214 * to drop into kdebug() when: 215 * - a lock heirarchy violation occurs 216 * - locks are held when going to sleep. 217 */ 218#ifdef WITNESS_KDB 219int witness_kdb = 1; 220#else 221int witness_kdb = 0; 222#endif 223TUNABLE_INT("debug.witness.kdb", &witness_kdb); 224SYSCTL_INT(_debug_witness, OID_AUTO, kdb, CTLFLAG_RW, &witness_kdb, 0, ""); 225 226/* 227 * When KDB is enabled and witness_trace is set to 1, it will cause the system 228 * to print a stack trace: 229 * - a lock heirarchy violation occurs 230 * - locks are held when going to sleep. 231 */ 232int witness_trace = 1; 233TUNABLE_INT("debug.witness.trace", &witness_trace); 234SYSCTL_INT(_debug_witness, OID_AUTO, trace, CTLFLAG_RW, &witness_trace, 0, ""); 235#endif /* KDB */ 236 237#ifdef WITNESS_SKIPSPIN 238int witness_skipspin = 1; 239#else 240int witness_skipspin = 0; 241#endif 242TUNABLE_INT("debug.witness.skipspin", &witness_skipspin); 243SYSCTL_INT(_debug_witness, OID_AUTO, skipspin, CTLFLAG_RDTUN, 244 &witness_skipspin, 0, ""); 245 246static struct mtx w_mtx; 247static struct witness_list w_free = STAILQ_HEAD_INITIALIZER(w_free); 248static struct witness_list w_all = STAILQ_HEAD_INITIALIZER(w_all); 249static struct witness_list w_spin = STAILQ_HEAD_INITIALIZER(w_spin); 250static struct witness_list w_sleep = STAILQ_HEAD_INITIALIZER(w_sleep); 251static struct witness_child_list_entry *w_child_free = NULL; 252static struct lock_list_entry *w_lock_list_free = NULL; 253 254static struct witness w_data[WITNESS_COUNT]; 255static struct witness_child_list_entry w_childdata[WITNESS_CHILDCOUNT]; 256static struct lock_list_entry w_locklistdata[LOCK_CHILDCOUNT]; 257 258static struct witness_order_list_entry order_lists[] = { 259 { "proctree", &lock_class_sx }, 260 { "allproc", &lock_class_sx }, 261 { "Giant", &lock_class_mtx_sleep }, 262 { "filedesc structure", &lock_class_mtx_sleep }, 263 { "pipe mutex", &lock_class_mtx_sleep }, 264 { "sigio lock", &lock_class_mtx_sleep }, 265 { "process group", &lock_class_mtx_sleep }, 266 { "process lock", &lock_class_mtx_sleep }, 267 { "session", &lock_class_mtx_sleep }, 268 { "uidinfo hash", &lock_class_mtx_sleep }, 269 { "uidinfo struct", &lock_class_mtx_sleep }, 270 { "allprison", &lock_class_mtx_sleep }, 271 { NULL, NULL }, 272 /* 273 * Sockets 274 */ 275 { "filedesc structure", &lock_class_mtx_sleep }, 276 { "accept", &lock_class_mtx_sleep }, 277 { "so_snd", &lock_class_mtx_sleep }, 278 { "so_rcv", &lock_class_mtx_sleep }, 279 { "sellck", &lock_class_mtx_sleep }, 280 { NULL, NULL }, 281 /* 282 * Routing 283 */ 284 { "so_rcv", &lock_class_mtx_sleep }, 285 { "radix node head", &lock_class_mtx_sleep }, 286 { "rtentry", &lock_class_mtx_sleep }, 287 { "ifaddr", &lock_class_mtx_sleep }, 288 { NULL, NULL }, 289 /* 290 * UNIX Domain Sockets 291 */ 292 { "unp", &lock_class_mtx_sleep }, 293 { "so_snd", &lock_class_mtx_sleep }, 294 { NULL, NULL }, 295 /* 296 * UDP/IP 297 */ 298 { "udp", &lock_class_mtx_sleep }, 299 { "udpinp", &lock_class_mtx_sleep }, 300 { "so_snd", &lock_class_mtx_sleep }, 301 { NULL, NULL }, 302 /* 303 * TCP/IP 304 */ 305 { "tcp", &lock_class_mtx_sleep }, 306 { "tcpinp", &lock_class_mtx_sleep }, 307 { "so_snd", &lock_class_mtx_sleep }, 308 { NULL, NULL }, 309 /* 310 * SLIP 311 */ 312 { "slip_mtx", &lock_class_mtx_sleep }, 313 { "slip sc_mtx", &lock_class_mtx_sleep }, 314 { NULL, NULL }, 315 /* 316 * netatalk 317 */ 318 { "ddp_list_mtx", &lock_class_mtx_sleep }, 319 { "ddp_mtx", &lock_class_mtx_sleep }, 320 { NULL, NULL }, 321 /* 322 * BPF 323 */ 324 { "bpf global lock", &lock_class_mtx_sleep }, 325 { "bpf interface lock", &lock_class_mtx_sleep }, 326 { "bpf cdev lock", &lock_class_mtx_sleep }, 327 { NULL, NULL }, 328 /* 329 * spin locks 330 */ 331#ifdef SMP 332 { "ap boot", &lock_class_mtx_spin }, 333#endif 334 { "sio", &lock_class_mtx_spin }, 335#ifdef __i386__ 336 { "cy", &lock_class_mtx_spin }, 337#endif 338 { "uart_hwmtx", &lock_class_mtx_spin }, 339 { "sabtty", &lock_class_mtx_spin }, 340 { "zstty", &lock_class_mtx_spin }, 341 { "ng_node", &lock_class_mtx_spin }, 342 { "ng_worklist", &lock_class_mtx_spin }, 343 { "taskqueue_fast", &lock_class_mtx_spin }, 344 { "intr table", &lock_class_mtx_spin }, 345 { "ithread table lock", &lock_class_mtx_spin }, 346 { "sleepq chain", &lock_class_mtx_spin }, 347 { "sched lock", &lock_class_mtx_spin }, 348 { "turnstile chain", &lock_class_mtx_spin }, 349 { "td_contested", &lock_class_mtx_spin }, 350 { "callout", &lock_class_mtx_spin }, 351 { "entropy harvest mutex", &lock_class_mtx_spin }, 352 /* 353 * leaf locks 354 */ 355 { "allpmaps", &lock_class_mtx_spin }, 356 { "vm page queue free mutex", &lock_class_mtx_spin }, 357 { "icu", &lock_class_mtx_spin }, 358#ifdef SMP 359 { "smp rendezvous", &lock_class_mtx_spin }, 360#if defined(__i386__) || defined(__amd64__) 361 { "tlb", &lock_class_mtx_spin }, 362#endif 363#ifdef __sparc64__ 364 { "ipi", &lock_class_mtx_spin }, 365#endif 366#endif 367 { "clk", &lock_class_mtx_spin }, 368 { "mutex profiling lock", &lock_class_mtx_spin }, 369 { "kse zombie lock", &lock_class_mtx_spin }, 370 { "ALD Queue", &lock_class_mtx_spin }, 371#ifdef __ia64__ 372 { "MCA spin lock", &lock_class_mtx_spin }, 373#endif 374#if defined(__i386__) || defined(__amd64__) 375 { "pcicfg", &lock_class_mtx_spin }, 376#endif 377 { NULL, NULL }, 378 { NULL, NULL } 379}; 380 381#ifdef BLESSING 382/* 383 * Pairs of locks which have been blessed 384 * Don't complain about order problems with blessed locks 385 */ 386static struct witness_blessed blessed_list[] = { 387}; 388static int blessed_count = 389 sizeof(blessed_list) / sizeof(struct witness_blessed); 390#endif 391 392/* 393 * List of all locks in the system. 394 */ 395TAILQ_HEAD(, lock_object) all_locks = TAILQ_HEAD_INITIALIZER(all_locks); 396 397static struct mtx all_mtx = { 398 { &lock_class_mtx_sleep, /* mtx_object.lo_class */ 399 "All locks list", /* mtx_object.lo_name */ 400 "All locks list", /* mtx_object.lo_type */ 401 LO_INITIALIZED, /* mtx_object.lo_flags */ 402 { NULL, NULL }, /* mtx_object.lo_list */ 403 NULL }, /* mtx_object.lo_witness */ 404 MTX_UNOWNED, 0 /* mtx_lock, mtx_recurse */ 405}; 406 407/* 408 * This global is set to 0 once it becomes safe to use the witness code. 409 */ 410static int witness_cold = 1; 411 412/* 413 * Global variables for book keeping. 414 */ 415static int lock_cur_cnt; 416static int lock_max_cnt; 417 418/* 419 * The WITNESS-enabled diagnostic code. 420 */ 421static void 422witness_initialize(void *dummy __unused) 423{ 424 struct lock_object *lock; 425 struct witness_order_list_entry *order; 426 struct witness *w, *w1; 427 int i; 428 429 /* 430 * We have to release Giant before initializing its witness 431 * structure so that WITNESS doesn't get confused. 432 */ 433 mtx_unlock(&Giant); 434 mtx_assert(&Giant, MA_NOTOWNED); 435 436 CTR1(KTR_WITNESS, "%s: initializing witness", __func__); 437 TAILQ_INSERT_HEAD(&all_locks, &all_mtx.mtx_object, lo_list); 438 mtx_init(&w_mtx, "witness lock", NULL, MTX_SPIN | MTX_QUIET | 439 MTX_NOWITNESS); 440 for (i = 0; i < WITNESS_COUNT; i++) 441 witness_free(&w_data[i]); 442 for (i = 0; i < WITNESS_CHILDCOUNT; i++) 443 witness_child_free(&w_childdata[i]); 444 for (i = 0; i < LOCK_CHILDCOUNT; i++) 445 witness_lock_list_free(&w_locklistdata[i]); 446 447 /* First add in all the specified order lists. */ 448 for (order = order_lists; order->w_name != NULL; order++) { 449 w = enroll(order->w_name, order->w_class); 450 if (w == NULL) 451 continue; 452 w->w_file = "order list"; 453 for (order++; order->w_name != NULL; order++) { 454 w1 = enroll(order->w_name, order->w_class); 455 if (w1 == NULL) 456 continue; 457 w1->w_file = "order list"; 458 if (!itismychild(w, w1)) 459 panic("Not enough memory for static orders!"); 460 w = w1; 461 } 462 } 463 464 /* Iterate through all locks and add them to witness. */ 465 mtx_lock(&all_mtx); 466 TAILQ_FOREACH(lock, &all_locks, lo_list) { 467 if (lock->lo_flags & LO_WITNESS) 468 lock->lo_witness = enroll(lock->lo_type, 469 lock->lo_class); 470 else 471 lock->lo_witness = NULL; 472 } 473 mtx_unlock(&all_mtx); 474 475 /* Mark the witness code as being ready for use. */ 476 atomic_store_rel_int(&witness_cold, 0); 477 478 mtx_lock(&Giant); 479} 480SYSINIT(witness_init, SI_SUB_WITNESS, SI_ORDER_FIRST, witness_initialize, NULL) 481 482static int 483sysctl_debug_witness_watch(SYSCTL_HANDLER_ARGS) 484{ 485 int error, value; 486 487 value = witness_watch; 488 error = sysctl_handle_int(oidp, &value, 0, req); 489 if (error != 0 || req->newptr == NULL) 490 return (error); 491 error = suser(req->td); 492 if (error != 0) 493 return (error); 494 if (value == witness_watch) 495 return (0); 496 if (value != 0) 497 return (EINVAL); 498 witness_watch = 0; 499 return (0); 500} 501 502void 503witness_init(struct lock_object *lock) 504{ 505 struct lock_class *class; 506 507 class = lock->lo_class; 508 if (lock->lo_flags & LO_INITIALIZED) 509 panic("%s: lock (%s) %s is already initialized", __func__, 510 class->lc_name, lock->lo_name); 511 if ((lock->lo_flags & LO_RECURSABLE) != 0 && 512 (class->lc_flags & LC_RECURSABLE) == 0) 513 panic("%s: lock (%s) %s can not be recursable", __func__, 514 class->lc_name, lock->lo_name); 515 if ((lock->lo_flags & LO_SLEEPABLE) != 0 && 516 (class->lc_flags & LC_SLEEPABLE) == 0) 517 panic("%s: lock (%s) %s can not be sleepable", __func__, 518 class->lc_name, lock->lo_name); 519 if ((lock->lo_flags & LO_UPGRADABLE) != 0 && 520 (class->lc_flags & LC_UPGRADABLE) == 0) 521 panic("%s: lock (%s) %s can not be upgradable", __func__, 522 class->lc_name, lock->lo_name); 523 524 mtx_lock(&all_mtx); 525 TAILQ_INSERT_TAIL(&all_locks, lock, lo_list); 526 lock->lo_flags |= LO_INITIALIZED; 527 lock_cur_cnt++; 528 if (lock_cur_cnt > lock_max_cnt) 529 lock_max_cnt = lock_cur_cnt; 530 mtx_unlock(&all_mtx); 531 if (!witness_cold && witness_watch != 0 && panicstr == NULL && 532 (lock->lo_flags & LO_WITNESS) != 0) 533 lock->lo_witness = enroll(lock->lo_type, class); 534 else 535 lock->lo_witness = NULL; 536} 537 538void 539witness_destroy(struct lock_object *lock) 540{ 541 struct witness *w; 542 543 if (witness_cold) 544 panic("lock (%s) %s destroyed while witness_cold", 545 lock->lo_class->lc_name, lock->lo_name); 546 if ((lock->lo_flags & LO_INITIALIZED) == 0) 547 panic("%s: lock (%s) %s is not initialized", __func__, 548 lock->lo_class->lc_name, lock->lo_name); 549 550 /* XXX: need to verify that no one holds the lock */ 551 w = lock->lo_witness; 552 if (w != NULL) { 553 mtx_lock_spin(&w_mtx); 554 MPASS(w->w_refcount > 0); 555 w->w_refcount--; 556 557 /* 558 * Lock is already released if we have an allocation failure 559 * and depart() fails. 560 */ 561 if (w->w_refcount != 0 || depart(w)) 562 mtx_unlock_spin(&w_mtx); 563 } 564 565 mtx_lock(&all_mtx); 566 lock_cur_cnt--; 567 TAILQ_REMOVE(&all_locks, lock, lo_list); 568 lock->lo_flags &= ~LO_INITIALIZED; 569 mtx_unlock(&all_mtx); 570} 571 572#ifdef DDB 573static void 574witness_display_list(void(*prnt)(const char *fmt, ...), 575 struct witness_list *list) 576{ 577 struct witness *w; 578 579 STAILQ_FOREACH(w, list, w_typelist) { 580 if (w->w_file == NULL || w->w_level > 0) 581 continue; 582 /* 583 * This lock has no anscestors, display its descendants. 584 */ 585 witness_displaydescendants(prnt, w, 0); 586 } 587} 588 589static void 590witness_display(void(*prnt)(const char *fmt, ...)) 591{ 592 struct witness *w; 593 594 KASSERT(!witness_cold, ("%s: witness_cold", __func__)); 595 witness_levelall(); 596 597 /* Clear all the displayed flags. */ 598 STAILQ_FOREACH(w, &w_all, w_list) { 599 w->w_displayed = 0; 600 } 601 602 /* 603 * First, handle sleep locks which have been acquired at least 604 * once. 605 */ 606 prnt("Sleep locks:\n"); 607 witness_display_list(prnt, &w_sleep); 608 609 /* 610 * Now do spin locks which have been acquired at least once. 611 */ 612 prnt("\nSpin locks:\n"); 613 witness_display_list(prnt, &w_spin); 614 615 /* 616 * Finally, any locks which have not been acquired yet. 617 */ 618 prnt("\nLocks which were never acquired:\n"); 619 STAILQ_FOREACH(w, &w_all, w_list) { 620 if (w->w_file != NULL || w->w_refcount == 0) 621 continue; 622 prnt("%s\n", w->w_name); 623 } 624} 625#endif /* DDB */ 626 627/* Trim useless garbage from filenames. */ 628static const char * 629fixup_filename(const char *file) 630{ 631 632 if (file == NULL) 633 return (NULL); 634 while (strncmp(file, "../", 3) == 0) 635 file += 3; 636 return (file); 637} 638 639int 640witness_defineorder(struct lock_object *lock1, struct lock_object *lock2) 641{ 642 643 if (witness_watch == 0 || panicstr != NULL) 644 return (0); 645 646 /* Require locks that witness knows about. */ 647 if (lock1 == NULL || lock1->lo_witness == NULL || lock2 == NULL || 648 lock2->lo_witness == NULL) 649 return (EINVAL); 650 651 MPASS(!mtx_owned(&w_mtx)); 652 mtx_lock_spin(&w_mtx); 653 654 /* 655 * If we already have either an explicit or implied lock order that 656 * is the other way around, then return an error. 657 */ 658 if (isitmydescendant(lock2->lo_witness, lock1->lo_witness)) { 659 mtx_unlock_spin(&w_mtx); 660 return (EDOOFUS); 661 } 662 663 /* Try to add the new order. */ 664 CTR3(KTR_WITNESS, "%s: adding %s as a child of %s", __func__, 665 lock2->lo_type, lock1->lo_type); 666 if (!itismychild(lock1->lo_witness, lock2->lo_witness)) 667 return (ENOMEM); 668 mtx_unlock_spin(&w_mtx); 669 return (0); 670} 671 672void 673witness_checkorder(struct lock_object *lock, int flags, const char *file, 674 int line) 675{ 676 struct lock_list_entry **lock_list, *lle; 677 struct lock_instance *lock1, *lock2; 678 struct lock_class *class; 679 struct witness *w, *w1; 680 struct thread *td; 681 int i, j; 682 683 if (witness_cold || witness_watch == 0 || lock->lo_witness == NULL || 684 panicstr != NULL) 685 return; 686 687 /* 688 * Try locks do not block if they fail to acquire the lock, thus 689 * there is no danger of deadlocks or of switching while holding a 690 * spin lock if we acquire a lock via a try operation. This 691 * function shouldn't even be called for try locks, so panic if 692 * that happens. 693 */ 694 if (flags & LOP_TRYLOCK) 695 panic("%s should not be called for try lock operations", 696 __func__); 697 698 w = lock->lo_witness; 699 class = lock->lo_class; 700 td = curthread; 701 file = fixup_filename(file); 702 703 if (class->lc_flags & LC_SLEEPLOCK) { 704 /* 705 * Since spin locks include a critical section, this check 706 * implicitly enforces a lock order of all sleep locks before 707 * all spin locks. 708 */ 709 if (td->td_critnest != 0 && !kdb_active) 710 panic("blockable sleep lock (%s) %s @ %s:%d", 711 class->lc_name, lock->lo_name, file, line); 712 713 /* 714 * If this is the first lock acquired then just return as 715 * no order checking is needed. 716 */ 717 if (td->td_sleeplocks == NULL) 718 return; 719 lock_list = &td->td_sleeplocks; 720 } else { 721 /* 722 * If this is the first lock, just return as no order 723 * checking is needed. We check this in both if clauses 724 * here as unifying the check would require us to use a 725 * critical section to ensure we don't migrate while doing 726 * the check. Note that if this is not the first lock, we 727 * are already in a critical section and are safe for the 728 * rest of the check. 729 */ 730 if (PCPU_GET(spinlocks) == NULL) 731 return; 732 lock_list = PCPU_PTR(spinlocks); 733 } 734 735 /* 736 * Check to see if we are recursing on a lock we already own. If 737 * so, make sure that we don't mismatch exclusive and shared lock 738 * acquires. 739 */ 740 lock1 = find_instance(*lock_list, lock); 741 if (lock1 != NULL) { 742 if ((lock1->li_flags & LI_EXCLUSIVE) != 0 && 743 (flags & LOP_EXCLUSIVE) == 0) { 744 printf("shared lock of (%s) %s @ %s:%d\n", 745 class->lc_name, lock->lo_name, file, line); 746 printf("while exclusively locked from %s:%d\n", 747 lock1->li_file, lock1->li_line); 748 panic("share->excl"); 749 } 750 if ((lock1->li_flags & LI_EXCLUSIVE) == 0 && 751 (flags & LOP_EXCLUSIVE) != 0) { 752 printf("exclusive lock of (%s) %s @ %s:%d\n", 753 class->lc_name, lock->lo_name, file, line); 754 printf("while share locked from %s:%d\n", 755 lock1->li_file, lock1->li_line); 756 panic("excl->share"); 757 } 758 return; 759 } 760 761 /* 762 * Try locks do not block if they fail to acquire the lock, thus 763 * there is no danger of deadlocks or of switching while holding a 764 * spin lock if we acquire a lock via a try operation. 765 */ 766 if (flags & LOP_TRYLOCK) 767 return; 768 769 /* 770 * Check for duplicate locks of the same type. Note that we only 771 * have to check for this on the last lock we just acquired. Any 772 * other cases will be caught as lock order violations. 773 */ 774 lock1 = &(*lock_list)->ll_children[(*lock_list)->ll_count - 1]; 775 w1 = lock1->li_lock->lo_witness; 776 if (w1 == w) { 777 if (w->w_same_squawked || (lock->lo_flags & LO_DUPOK)) 778 return; 779 w->w_same_squawked = 1; 780 printf("acquiring duplicate lock of same type: \"%s\"\n", 781 lock->lo_type); 782 printf(" 1st %s @ %s:%d\n", lock1->li_lock->lo_name, 783 lock1->li_file, lock1->li_line); 784 printf(" 2nd %s @ %s:%d\n", lock->lo_name, file, line); 785#ifdef KDB 786 goto debugger; 787#else 788 return; 789#endif 790 } 791 MPASS(!mtx_owned(&w_mtx)); 792 mtx_lock_spin(&w_mtx); 793 /* 794 * If we have a known higher number just say ok 795 */ 796 if (witness_watch > 1 && w->w_level > w1->w_level) { 797 mtx_unlock_spin(&w_mtx); 798 return; 799 } 800 /* 801 * If we know that the the lock we are acquiring comes after 802 * the lock we most recently acquired in the lock order tree, 803 * then there is no need for any further checks. 804 */ 805 if (isitmydescendant(w1, w)) { 806 mtx_unlock_spin(&w_mtx); 807 return; 808 } 809 for (j = 0, lle = *lock_list; lle != NULL; lle = lle->ll_next) { 810 for (i = lle->ll_count - 1; i >= 0; i--, j++) { 811 812 MPASS(j < WITNESS_COUNT); 813 lock1 = &lle->ll_children[i]; 814 w1 = lock1->li_lock->lo_witness; 815 816 /* 817 * If this lock doesn't undergo witness checking, 818 * then skip it. 819 */ 820 if (w1 == NULL) { 821 KASSERT((lock1->li_lock->lo_flags & LO_WITNESS) == 0, 822 ("lock missing witness structure")); 823 continue; 824 } 825 /* 826 * If we are locking Giant and this is a sleepable 827 * lock, then skip it. 828 */ 829 if ((lock1->li_lock->lo_flags & LO_SLEEPABLE) != 0 && 830 lock == &Giant.mtx_object) 831 continue; 832 /* 833 * If we are locking a sleepable lock and this lock 834 * is Giant, then skip it. 835 */ 836 if ((lock->lo_flags & LO_SLEEPABLE) != 0 && 837 lock1->li_lock == &Giant.mtx_object) 838 continue; 839 /* 840 * If we are locking a sleepable lock and this lock 841 * isn't sleepable, we want to treat it as a lock 842 * order violation to enfore a general lock order of 843 * sleepable locks before non-sleepable locks. 844 */ 845 if (!((lock->lo_flags & LO_SLEEPABLE) != 0 && 846 (lock1->li_lock->lo_flags & LO_SLEEPABLE) == 0)) 847 /* 848 * Check the lock order hierarchy for a reveresal. 849 */ 850 if (!isitmydescendant(w, w1)) 851 continue; 852 /* 853 * We have a lock order violation, check to see if it 854 * is allowed or has already been yelled about. 855 */ 856 mtx_unlock_spin(&w_mtx); 857#ifdef BLESSING 858 /* 859 * If the lock order is blessed, just bail. We don't 860 * look for other lock order violations though, which 861 * may be a bug. 862 */ 863 if (blessed(w, w1)) 864 return; 865#endif 866 if (lock1->li_lock == &Giant.mtx_object) { 867 if (w1->w_Giant_squawked) 868 return; 869 else 870 w1->w_Giant_squawked = 1; 871 } else { 872 if (w1->w_other_squawked) 873 return; 874 else 875 w1->w_other_squawked = 1; 876 } 877 /* 878 * Ok, yell about it. 879 */ 880 printf("lock order reversal\n"); 881 /* 882 * Try to locate an earlier lock with 883 * witness w in our list. 884 */ 885 do { 886 lock2 = &lle->ll_children[i]; 887 MPASS(lock2->li_lock != NULL); 888 if (lock2->li_lock->lo_witness == w) 889 break; 890 if (i == 0 && lle->ll_next != NULL) { 891 lle = lle->ll_next; 892 i = lle->ll_count - 1; 893 MPASS(i >= 0 && i < LOCK_NCHILDREN); 894 } else 895 i--; 896 } while (i >= 0); 897 if (i < 0) { 898 printf(" 1st %p %s (%s) @ %s:%d\n", 899 lock1->li_lock, lock1->li_lock->lo_name, 900 lock1->li_lock->lo_type, lock1->li_file, 901 lock1->li_line); 902 printf(" 2nd %p %s (%s) @ %s:%d\n", lock, 903 lock->lo_name, lock->lo_type, file, line); 904 } else { 905 printf(" 1st %p %s (%s) @ %s:%d\n", 906 lock2->li_lock, lock2->li_lock->lo_name, 907 lock2->li_lock->lo_type, lock2->li_file, 908 lock2->li_line); 909 printf(" 2nd %p %s (%s) @ %s:%d\n", 910 lock1->li_lock, lock1->li_lock->lo_name, 911 lock1->li_lock->lo_type, lock1->li_file, 912 lock1->li_line); 913 printf(" 3rd %p %s (%s) @ %s:%d\n", lock, 914 lock->lo_name, lock->lo_type, file, line); 915 } 916#ifdef KDB 917 goto debugger; 918#else 919 return; 920#endif 921 } 922 } 923 lock1 = &(*lock_list)->ll_children[(*lock_list)->ll_count - 1]; 924 /* 925 * If requested, build a new lock order. However, don't build a new 926 * relationship between a sleepable lock and Giant if it is in the 927 * wrong direction. The correct lock order is that sleepable locks 928 * always come before Giant. 929 */ 930 if (flags & LOP_NEWORDER && 931 !(lock1->li_lock == &Giant.mtx_object && 932 (lock->lo_flags & LO_SLEEPABLE) != 0)) { 933 CTR3(KTR_WITNESS, "%s: adding %s as a child of %s", __func__, 934 lock->lo_type, lock1->li_lock->lo_type); 935 if (!itismychild(lock1->li_lock->lo_witness, w)) 936 /* Witness is dead. */ 937 return; 938 } 939 mtx_unlock_spin(&w_mtx); 940 return; 941 942#ifdef KDB 943debugger: 944 if (witness_trace) 945 kdb_backtrace(); 946 if (witness_kdb) 947 kdb_enter(__func__); 948#endif 949} 950 951void 952witness_lock(struct lock_object *lock, int flags, const char *file, int line) 953{ 954 struct lock_list_entry **lock_list, *lle; 955 struct lock_instance *instance; 956 struct witness *w; 957 struct thread *td; 958 959 if (witness_cold || witness_watch == 0 || lock->lo_witness == NULL || 960 panicstr != NULL) 961 return; 962 w = lock->lo_witness; 963 td = curthread; 964 file = fixup_filename(file); 965 966 /* Determine lock list for this lock. */ 967 if (lock->lo_class->lc_flags & LC_SLEEPLOCK) 968 lock_list = &td->td_sleeplocks; 969 else 970 lock_list = PCPU_PTR(spinlocks); 971 972 /* Check to see if we are recursing on a lock we already own. */ 973 instance = find_instance(*lock_list, lock); 974 if (instance != NULL) { 975 instance->li_flags++; 976 CTR4(KTR_WITNESS, "%s: pid %d recursed on %s r=%d", __func__, 977 td->td_proc->p_pid, lock->lo_name, 978 instance->li_flags & LI_RECURSEMASK); 979 instance->li_file = file; 980 instance->li_line = line; 981 return; 982 } 983 984 /* Update per-witness last file and line acquire. */ 985 w->w_file = file; 986 w->w_line = line; 987 988 /* Find the next open lock instance in the list and fill it. */ 989 lle = *lock_list; 990 if (lle == NULL || lle->ll_count == LOCK_NCHILDREN) { 991 lle = witness_lock_list_get(); 992 if (lle == NULL) 993 return; 994 lle->ll_next = *lock_list; 995 CTR3(KTR_WITNESS, "%s: pid %d added lle %p", __func__, 996 td->td_proc->p_pid, lle); 997 *lock_list = lle; 998 } 999 instance = &lle->ll_children[lle->ll_count++]; 1000 instance->li_lock = lock; 1001 instance->li_line = line; 1002 instance->li_file = file; 1003 if ((flags & LOP_EXCLUSIVE) != 0) 1004 instance->li_flags = LI_EXCLUSIVE; 1005 else 1006 instance->li_flags = 0; 1007 CTR4(KTR_WITNESS, "%s: pid %d added %s as lle[%d]", __func__, 1008 td->td_proc->p_pid, lock->lo_name, lle->ll_count - 1); 1009} 1010 1011void 1012witness_upgrade(struct lock_object *lock, int flags, const char *file, int line) 1013{ 1014 struct lock_instance *instance; 1015 struct lock_class *class; 1016 1017 KASSERT(!witness_cold, ("%s: witness_cold", __func__)); 1018 if (lock->lo_witness == NULL || witness_watch == 0 || panicstr != NULL) 1019 return; 1020 class = lock->lo_class; 1021 file = fixup_filename(file); 1022 if ((lock->lo_flags & LO_UPGRADABLE) == 0) 1023 panic("upgrade of non-upgradable lock (%s) %s @ %s:%d", 1024 class->lc_name, lock->lo_name, file, line); 1025 if ((flags & LOP_TRYLOCK) == 0) 1026 panic("non-try upgrade of lock (%s) %s @ %s:%d", class->lc_name, 1027 lock->lo_name, file, line); 1028 if ((lock->lo_class->lc_flags & LC_SLEEPLOCK) == 0) 1029 panic("upgrade of non-sleep lock (%s) %s @ %s:%d", 1030 class->lc_name, lock->lo_name, file, line); 1031 instance = find_instance(curthread->td_sleeplocks, lock); 1032 if (instance == NULL) 1033 panic("upgrade of unlocked lock (%s) %s @ %s:%d", 1034 class->lc_name, lock->lo_name, file, line); 1035 if ((instance->li_flags & LI_EXCLUSIVE) != 0) 1036 panic("upgrade of exclusive lock (%s) %s @ %s:%d", 1037 class->lc_name, lock->lo_name, file, line); 1038 if ((instance->li_flags & LI_RECURSEMASK) != 0) 1039 panic("upgrade of recursed lock (%s) %s r=%d @ %s:%d", 1040 class->lc_name, lock->lo_name, 1041 instance->li_flags & LI_RECURSEMASK, file, line); 1042 instance->li_flags |= LI_EXCLUSIVE; 1043} 1044 1045void 1046witness_downgrade(struct lock_object *lock, int flags, const char *file, 1047 int line) 1048{ 1049 struct lock_instance *instance; 1050 struct lock_class *class; 1051 1052 KASSERT(!witness_cold, ("%s: witness_cold", __func__)); 1053 if (lock->lo_witness == NULL || witness_watch == 0 || panicstr != NULL) 1054 return; 1055 class = lock->lo_class; 1056 file = fixup_filename(file); 1057 if ((lock->lo_flags & LO_UPGRADABLE) == 0) 1058 panic("downgrade of non-upgradable lock (%s) %s @ %s:%d", 1059 class->lc_name, lock->lo_name, file, line); 1060 if ((lock->lo_class->lc_flags & LC_SLEEPLOCK) == 0) 1061 panic("downgrade of non-sleep lock (%s) %s @ %s:%d", 1062 class->lc_name, lock->lo_name, file, line); 1063 instance = find_instance(curthread->td_sleeplocks, lock); 1064 if (instance == NULL) 1065 panic("downgrade of unlocked lock (%s) %s @ %s:%d", 1066 class->lc_name, lock->lo_name, file, line); 1067 if ((instance->li_flags & LI_EXCLUSIVE) == 0) 1068 panic("downgrade of shared lock (%s) %s @ %s:%d", 1069 class->lc_name, lock->lo_name, file, line); 1070 if ((instance->li_flags & LI_RECURSEMASK) != 0) 1071 panic("downgrade of recursed lock (%s) %s r=%d @ %s:%d", 1072 class->lc_name, lock->lo_name, 1073 instance->li_flags & LI_RECURSEMASK, file, line); 1074 instance->li_flags &= ~LI_EXCLUSIVE; 1075} 1076 1077void 1078witness_unlock(struct lock_object *lock, int flags, const char *file, int line) 1079{ 1080 struct lock_list_entry **lock_list, *lle; 1081 struct lock_instance *instance; 1082 struct lock_class *class; 1083 struct thread *td; 1084 register_t s; 1085 int i, j; 1086 1087 if (witness_cold || witness_watch == 0 || lock->lo_witness == NULL || 1088 panicstr != NULL) 1089 return; 1090 td = curthread; 1091 class = lock->lo_class; 1092 file = fixup_filename(file); 1093 1094 /* Find lock instance associated with this lock. */ 1095 if (class->lc_flags & LC_SLEEPLOCK) 1096 lock_list = &td->td_sleeplocks; 1097 else 1098 lock_list = PCPU_PTR(spinlocks); 1099 for (; *lock_list != NULL; lock_list = &(*lock_list)->ll_next) 1100 for (i = 0; i < (*lock_list)->ll_count; i++) { 1101 instance = &(*lock_list)->ll_children[i]; 1102 if (instance->li_lock == lock) 1103 goto found; 1104 } 1105 panic("lock (%s) %s not locked @ %s:%d", class->lc_name, lock->lo_name, 1106 file, line); 1107found: 1108 1109 /* First, check for shared/exclusive mismatches. */ 1110 if ((instance->li_flags & LI_EXCLUSIVE) != 0 && 1111 (flags & LOP_EXCLUSIVE) == 0) { 1112 printf("shared unlock of (%s) %s @ %s:%d\n", class->lc_name, 1113 lock->lo_name, file, line); 1114 printf("while exclusively locked from %s:%d\n", 1115 instance->li_file, instance->li_line); 1116 panic("excl->ushare"); 1117 } 1118 if ((instance->li_flags & LI_EXCLUSIVE) == 0 && 1119 (flags & LOP_EXCLUSIVE) != 0) { 1120 printf("exclusive unlock of (%s) %s @ %s:%d\n", class->lc_name, 1121 lock->lo_name, file, line); 1122 printf("while share locked from %s:%d\n", instance->li_file, 1123 instance->li_line); 1124 panic("share->uexcl"); 1125 } 1126 1127 /* If we are recursed, unrecurse. */ 1128 if ((instance->li_flags & LI_RECURSEMASK) > 0) { 1129 CTR4(KTR_WITNESS, "%s: pid %d unrecursed on %s r=%d", __func__, 1130 td->td_proc->p_pid, instance->li_lock->lo_name, 1131 instance->li_flags); 1132 instance->li_flags--; 1133 return; 1134 } 1135 1136 /* Otherwise, remove this item from the list. */ 1137 s = intr_disable(); 1138 CTR4(KTR_WITNESS, "%s: pid %d removed %s from lle[%d]", __func__, 1139 td->td_proc->p_pid, instance->li_lock->lo_name, 1140 (*lock_list)->ll_count - 1); 1141 for (j = i; j < (*lock_list)->ll_count - 1; j++) 1142 (*lock_list)->ll_children[j] = 1143 (*lock_list)->ll_children[j + 1]; 1144 (*lock_list)->ll_count--; 1145 intr_restore(s); 1146 1147 /* If this lock list entry is now empty, free it. */ 1148 if ((*lock_list)->ll_count == 0) { 1149 lle = *lock_list; 1150 *lock_list = lle->ll_next; 1151 CTR3(KTR_WITNESS, "%s: pid %d removed lle %p", __func__, 1152 td->td_proc->p_pid, lle); 1153 witness_lock_list_free(lle); 1154 } 1155} 1156 1157/* 1158 * Warn if any locks other than 'lock' are held. Flags can be passed in to 1159 * exempt Giant and sleepable locks from the checks as well. If any 1160 * non-exempt locks are held, then a supplied message is printed to the 1161 * console along with a list of the offending locks. If indicated in the 1162 * flags then a failure results in a panic as well. 1163 */ 1164int 1165witness_warn(int flags, struct lock_object *lock, const char *fmt, ...) 1166{ 1167 struct lock_list_entry *lle; 1168 struct lock_instance *lock1; 1169 struct thread *td; 1170 va_list ap; 1171 int i, n; 1172 1173 if (witness_cold || witness_watch == 0 || panicstr != NULL) 1174 return (0); 1175 n = 0; 1176 td = curthread; 1177 for (lle = td->td_sleeplocks; lle != NULL; lle = lle->ll_next) 1178 for (i = lle->ll_count - 1; i >= 0; i--) { 1179 lock1 = &lle->ll_children[i]; 1180 if (lock1->li_lock == lock) 1181 continue; 1182 if (flags & WARN_GIANTOK && 1183 lock1->li_lock == &Giant.mtx_object) 1184 continue; 1185 if (flags & WARN_SLEEPOK && 1186 (lock1->li_lock->lo_flags & LO_SLEEPABLE) != 0) 1187 continue; 1188 if (n == 0) { 1189 va_start(ap, fmt); 1190 vprintf(fmt, ap); 1191 va_end(ap); 1192 printf(" with the following"); 1193 if (flags & WARN_SLEEPOK) 1194 printf(" non-sleepable"); 1195 printf(" locks held:\n"); 1196 } 1197 n++; 1198 witness_list_lock(lock1); 1199 } 1200 if (PCPU_GET(spinlocks) != NULL) { 1201 /* 1202 * Since we already hold a spinlock preemption is 1203 * already blocked. 1204 */ 1205 if (n == 0) { 1206 va_start(ap, fmt); 1207 vprintf(fmt, ap); 1208 va_end(ap); 1209 printf(" with the following"); 1210 if (flags & WARN_SLEEPOK) 1211 printf(" non-sleepable"); 1212 printf(" locks held:\n"); 1213 } 1214 n += witness_list_locks(PCPU_PTR(spinlocks)); 1215 } 1216 if (flags & WARN_PANIC && n) 1217 panic("witness_warn"); 1218#ifdef KDB 1219 else if (witness_kdb && n) 1220 kdb_enter(__func__); 1221 else if (witness_trace && n) 1222 kdb_backtrace(); 1223#endif 1224 return (n); 1225} 1226 1227const char * 1228witness_file(struct lock_object *lock) 1229{ 1230 struct witness *w; 1231 1232 if (witness_cold || witness_watch == 0 || lock->lo_witness == NULL) 1233 return ("?"); 1234 w = lock->lo_witness; 1235 return (w->w_file); 1236} 1237 1238int 1239witness_line(struct lock_object *lock) 1240{ 1241 struct witness *w; 1242 1243 if (witness_cold || witness_watch == 0 || lock->lo_witness == NULL) 1244 return (0); 1245 w = lock->lo_witness; 1246 return (w->w_line); 1247} 1248 1249static struct witness * 1250enroll(const char *description, struct lock_class *lock_class) 1251{ 1252 struct witness *w; 1253 1254 if (witness_watch == 0 || panicstr != NULL) 1255 return (NULL); 1256 if ((lock_class->lc_flags & LC_SPINLOCK) && witness_skipspin) 1257 return (NULL); 1258 mtx_lock_spin(&w_mtx); 1259 STAILQ_FOREACH(w, &w_all, w_list) { 1260 if (w->w_name == description || (w->w_refcount > 0 && 1261 strcmp(description, w->w_name) == 0)) { 1262 w->w_refcount++; 1263 mtx_unlock_spin(&w_mtx); 1264 if (lock_class != w->w_class) 1265 panic( 1266 "lock (%s) %s does not match earlier (%s) lock", 1267 description, lock_class->lc_name, 1268 w->w_class->lc_name); 1269 return (w); 1270 } 1271 } 1272 /* 1273 * This isn't quite right, as witness_cold is still 0 while we 1274 * enroll all the locks initialized before witness_initialize(). 1275 */ 1276 if ((lock_class->lc_flags & LC_SPINLOCK) && !witness_cold) { 1277 mtx_unlock_spin(&w_mtx); 1278 panic("spin lock %s not in order list", description); 1279 } 1280 if ((w = witness_get()) == NULL) 1281 return (NULL); 1282 w->w_name = description; 1283 w->w_class = lock_class; 1284 w->w_refcount = 1; 1285 STAILQ_INSERT_HEAD(&w_all, w, w_list); 1286 if (lock_class->lc_flags & LC_SPINLOCK) 1287 STAILQ_INSERT_HEAD(&w_spin, w, w_typelist); 1288 else if (lock_class->lc_flags & LC_SLEEPLOCK) 1289 STAILQ_INSERT_HEAD(&w_sleep, w, w_typelist); 1290 else { 1291 mtx_unlock_spin(&w_mtx); 1292 panic("lock class %s is not sleep or spin", 1293 lock_class->lc_name); 1294 } 1295 mtx_unlock_spin(&w_mtx); 1296 return (w); 1297} 1298 1299/* Don't let the door bang you on the way out... */ 1300static int 1301depart(struct witness *w) 1302{ 1303 struct witness_child_list_entry *wcl, *nwcl; 1304 struct witness_list *list; 1305 struct witness *parent; 1306 1307 MPASS(w->w_refcount == 0); 1308 if (w->w_class->lc_flags & LC_SLEEPLOCK) 1309 list = &w_sleep; 1310 else 1311 list = &w_spin; 1312 /* 1313 * First, we run through the entire tree looking for any 1314 * witnesses that the outgoing witness is a child of. For 1315 * each parent that we find, we reparent all the direct 1316 * children of the outgoing witness to its parent. 1317 */ 1318 STAILQ_FOREACH(parent, list, w_typelist) { 1319 if (!isitmychild(parent, w)) 1320 continue; 1321 removechild(parent, w); 1322 if (!reparentchildren(parent, w)) 1323 return (0); 1324 } 1325 1326 /* 1327 * Now we go through and free up the child list of the 1328 * outgoing witness. 1329 */ 1330 for (wcl = w->w_children; wcl != NULL; wcl = nwcl) { 1331 nwcl = wcl->wcl_next; 1332 witness_child_free(wcl); 1333 } 1334 1335 /* 1336 * Detach from various lists and free. 1337 */ 1338 STAILQ_REMOVE(list, w, witness, w_typelist); 1339 STAILQ_REMOVE(&w_all, w, witness, w_list); 1340 witness_free(w); 1341 1342 /* Finally, fixup the tree. */ 1343 return (rebalancetree(list)); 1344} 1345 1346/* 1347 * Prune an entire lock order tree. We look for cases where a lock 1348 * is now both a descendant and a direct child of a given lock. In 1349 * that case, we want to remove the direct child link from the tree. 1350 * 1351 * Returns false if insertchild() fails. 1352 */ 1353static int 1354rebalancetree(struct witness_list *list) 1355{ 1356 struct witness *child, *parent; 1357 1358 STAILQ_FOREACH(child, list, w_typelist) { 1359 STAILQ_FOREACH(parent, list, w_typelist) { 1360 if (!isitmychild(parent, child)) 1361 continue; 1362 removechild(parent, child); 1363 if (isitmydescendant(parent, child)) 1364 continue; 1365 if (!insertchild(parent, child)) 1366 return (0); 1367 } 1368 } 1369 witness_levelall(); 1370 return (1); 1371} 1372 1373/* 1374 * Add "child" as a direct child of "parent". Returns false if 1375 * we fail due to out of memory. 1376 */ 1377static int 1378insertchild(struct witness *parent, struct witness *child) 1379{ 1380 struct witness_child_list_entry **wcl; 1381 1382 MPASS(child != NULL && parent != NULL); 1383 1384 /* 1385 * Insert "child" after "parent" 1386 */ 1387 wcl = &parent->w_children; 1388 while (*wcl != NULL && (*wcl)->wcl_count == WITNESS_NCHILDREN) 1389 wcl = &(*wcl)->wcl_next; 1390 if (*wcl == NULL) { 1391 *wcl = witness_child_get(); 1392 if (*wcl == NULL) 1393 return (0); 1394 } 1395 (*wcl)->wcl_children[(*wcl)->wcl_count++] = child; 1396 1397 return (1); 1398} 1399 1400/* 1401 * Make all the direct descendants of oldparent be direct descendants 1402 * of newparent. 1403 */ 1404static int 1405reparentchildren(struct witness *newparent, struct witness *oldparent) 1406{ 1407 struct witness_child_list_entry *wcl; 1408 int i; 1409 1410 /* Avoid making a witness a child of itself. */ 1411 MPASS(!isitmychild(oldparent, newparent)); 1412 1413 for (wcl = oldparent->w_children; wcl != NULL; wcl = wcl->wcl_next) 1414 for (i = 0; i < wcl->wcl_count; i++) 1415 if (!insertchild(newparent, wcl->wcl_children[i])) 1416 return (0); 1417 return (1); 1418} 1419 1420static int 1421itismychild(struct witness *parent, struct witness *child) 1422{ 1423 struct witness_list *list; 1424 1425 MPASS(child != NULL && parent != NULL); 1426 if ((parent->w_class->lc_flags & (LC_SLEEPLOCK | LC_SPINLOCK)) != 1427 (child->w_class->lc_flags & (LC_SLEEPLOCK | LC_SPINLOCK))) 1428 panic( 1429 "%s: parent (%s) and child (%s) are not the same lock type", 1430 __func__, parent->w_class->lc_name, 1431 child->w_class->lc_name); 1432 1433 if (!insertchild(parent, child)) 1434 return (0); 1435 1436 if (parent->w_class->lc_flags & LC_SLEEPLOCK) 1437 list = &w_sleep; 1438 else 1439 list = &w_spin; 1440 return (rebalancetree(list)); 1441} 1442 1443static void 1444removechild(struct witness *parent, struct witness *child) 1445{ 1446 struct witness_child_list_entry **wcl, *wcl1; 1447 int i; 1448 1449 for (wcl = &parent->w_children; *wcl != NULL; wcl = &(*wcl)->wcl_next) 1450 for (i = 0; i < (*wcl)->wcl_count; i++) 1451 if ((*wcl)->wcl_children[i] == child) 1452 goto found; 1453 return; 1454found: 1455 (*wcl)->wcl_count--; 1456 if ((*wcl)->wcl_count > i) 1457 (*wcl)->wcl_children[i] = 1458 (*wcl)->wcl_children[(*wcl)->wcl_count]; 1459 MPASS((*wcl)->wcl_children[i] != NULL); 1460 if ((*wcl)->wcl_count != 0) 1461 return; 1462 wcl1 = *wcl; 1463 *wcl = wcl1->wcl_next; 1464 witness_child_free(wcl1); 1465} 1466 1467static int 1468isitmychild(struct witness *parent, struct witness *child) 1469{ 1470 struct witness_child_list_entry *wcl; 1471 int i; 1472 1473 for (wcl = parent->w_children; wcl != NULL; wcl = wcl->wcl_next) { 1474 for (i = 0; i < wcl->wcl_count; i++) { 1475 if (wcl->wcl_children[i] == child) 1476 return (1); 1477 } 1478 } 1479 return (0); 1480} 1481 1482static int 1483isitmydescendant(struct witness *parent, struct witness *child) 1484{ 1485 struct witness_child_list_entry *wcl; 1486 int i, j; 1487 1488 if (isitmychild(parent, child)) 1489 return (1); 1490 j = 0; 1491 for (wcl = parent->w_children; wcl != NULL; wcl = wcl->wcl_next) { 1492 MPASS(j < 1000); 1493 for (i = 0; i < wcl->wcl_count; i++) { 1494 if (isitmydescendant(wcl->wcl_children[i], child)) 1495 return (1); 1496 } 1497 j++; 1498 } 1499 return (0); 1500} 1501 1502static void 1503witness_levelall (void) 1504{ 1505 struct witness_list *list; 1506 struct witness *w, *w1; 1507 1508 /* 1509 * First clear all levels. 1510 */ 1511 STAILQ_FOREACH(w, &w_all, w_list) { 1512 w->w_level = 0; 1513 } 1514 1515 /* 1516 * Look for locks with no parent and level all their descendants. 1517 */ 1518 STAILQ_FOREACH(w, &w_all, w_list) { 1519 /* 1520 * This is just an optimization, technically we could get 1521 * away just walking the all list each time. 1522 */ 1523 if (w->w_class->lc_flags & LC_SLEEPLOCK) 1524 list = &w_sleep; 1525 else 1526 list = &w_spin; 1527 STAILQ_FOREACH(w1, list, w_typelist) { 1528 if (isitmychild(w1, w)) 1529 goto skip; 1530 } 1531 witness_leveldescendents(w, 0); 1532 skip: 1533 ; /* silence GCC 3.x */ 1534 } 1535} 1536 1537static void 1538witness_leveldescendents(struct witness *parent, int level) 1539{ 1540 struct witness_child_list_entry *wcl; 1541 int i; 1542 1543 if (parent->w_level < level) 1544 parent->w_level = level; 1545 level++; 1546 for (wcl = parent->w_children; wcl != NULL; wcl = wcl->wcl_next) 1547 for (i = 0; i < wcl->wcl_count; i++) 1548 witness_leveldescendents(wcl->wcl_children[i], level); 1549} 1550 1551static void 1552witness_displaydescendants(void(*prnt)(const char *fmt, ...), 1553 struct witness *parent, int indent) 1554{ 1555 struct witness_child_list_entry *wcl; 1556 int i, level; 1557 1558 level = parent->w_level; 1559 prnt("%-2d", level); 1560 for (i = 0; i < indent; i++) 1561 prnt(" "); 1562 if (parent->w_refcount > 0) 1563 prnt("%s", parent->w_name); 1564 else 1565 prnt("(dead)"); 1566 if (parent->w_displayed) { 1567 prnt(" -- (already displayed)\n"); 1568 return; 1569 } 1570 parent->w_displayed = 1; 1571 if (parent->w_refcount > 0) { 1572 if (parent->w_file != NULL) 1573 prnt(" -- last acquired @ %s:%d", parent->w_file, 1574 parent->w_line); 1575 } 1576 prnt("\n"); 1577 for (wcl = parent->w_children; wcl != NULL; wcl = wcl->wcl_next) 1578 for (i = 0; i < wcl->wcl_count; i++) 1579 witness_displaydescendants(prnt, 1580 wcl->wcl_children[i], indent + 1); 1581} 1582 1583#ifdef BLESSING 1584static int 1585blessed(struct witness *w1, struct witness *w2) 1586{ 1587 int i; 1588 struct witness_blessed *b; 1589 1590 for (i = 0; i < blessed_count; i++) { 1591 b = &blessed_list[i]; 1592 if (strcmp(w1->w_name, b->b_lock1) == 0) { 1593 if (strcmp(w2->w_name, b->b_lock2) == 0) 1594 return (1); 1595 continue; 1596 } 1597 if (strcmp(w1->w_name, b->b_lock2) == 0) 1598 if (strcmp(w2->w_name, b->b_lock1) == 0) 1599 return (1); 1600 } 1601 return (0); 1602} 1603#endif 1604 1605static struct witness * 1606witness_get(void) 1607{ 1608 struct witness *w; 1609 1610 if (witness_watch == 0) { 1611 mtx_unlock_spin(&w_mtx); 1612 return (NULL); 1613 } 1614 if (STAILQ_EMPTY(&w_free)) { 1615 witness_watch = 0; 1616 mtx_unlock_spin(&w_mtx); 1617 printf("%s: witness exhausted\n", __func__); 1618 return (NULL); 1619 } 1620 w = STAILQ_FIRST(&w_free); 1621 STAILQ_REMOVE_HEAD(&w_free, w_list); 1622 bzero(w, sizeof(*w)); 1623 return (w); 1624} 1625 1626static void 1627witness_free(struct witness *w) 1628{ 1629 1630 STAILQ_INSERT_HEAD(&w_free, w, w_list); 1631} 1632 1633static struct witness_child_list_entry * 1634witness_child_get(void) 1635{ 1636 struct witness_child_list_entry *wcl; 1637 1638 if (witness_watch == 0) { 1639 mtx_unlock_spin(&w_mtx); 1640 return (NULL); 1641 } 1642 wcl = w_child_free; 1643 if (wcl == NULL) { 1644 witness_watch = 0; 1645 mtx_unlock_spin(&w_mtx); 1646 printf("%s: witness exhausted\n", __func__); 1647 return (NULL); 1648 } 1649 w_child_free = wcl->wcl_next; 1650 bzero(wcl, sizeof(*wcl)); 1651 return (wcl); 1652} 1653 1654static void 1655witness_child_free(struct witness_child_list_entry *wcl) 1656{ 1657 1658 wcl->wcl_next = w_child_free; 1659 w_child_free = wcl; 1660} 1661 1662static struct lock_list_entry * 1663witness_lock_list_get(void) 1664{ 1665 struct lock_list_entry *lle; 1666 1667 if (witness_watch == 0) 1668 return (NULL); 1669 mtx_lock_spin(&w_mtx); 1670 lle = w_lock_list_free; 1671 if (lle == NULL) { 1672 witness_watch = 0; 1673 mtx_unlock_spin(&w_mtx); 1674 printf("%s: witness exhausted\n", __func__); 1675 return (NULL); 1676 } 1677 w_lock_list_free = lle->ll_next; 1678 mtx_unlock_spin(&w_mtx); 1679 bzero(lle, sizeof(*lle)); 1680 return (lle); 1681} 1682 1683static void 1684witness_lock_list_free(struct lock_list_entry *lle) 1685{ 1686 1687 mtx_lock_spin(&w_mtx); 1688 lle->ll_next = w_lock_list_free; 1689 w_lock_list_free = lle; 1690 mtx_unlock_spin(&w_mtx); 1691} 1692 1693static struct lock_instance * 1694find_instance(struct lock_list_entry *lock_list, struct lock_object *lock) 1695{ 1696 struct lock_list_entry *lle; 1697 struct lock_instance *instance; 1698 int i; 1699 1700 for (lle = lock_list; lle != NULL; lle = lle->ll_next) 1701 for (i = lle->ll_count - 1; i >= 0; i--) { 1702 instance = &lle->ll_children[i]; 1703 if (instance->li_lock == lock) 1704 return (instance); 1705 } 1706 return (NULL); 1707} 1708 1709static void 1710witness_list_lock(struct lock_instance *instance) 1711{ 1712 struct lock_object *lock; 1713 1714 lock = instance->li_lock; 1715 printf("%s %s %s", (instance->li_flags & LI_EXCLUSIVE) != 0 ? 1716 "exclusive" : "shared", lock->lo_class->lc_name, lock->lo_name); 1717 if (lock->lo_type != lock->lo_name) 1718 printf(" (%s)", lock->lo_type); 1719 printf(" r = %d (%p) locked @ %s:%d\n", 1720 instance->li_flags & LI_RECURSEMASK, lock, instance->li_file, 1721 instance->li_line); 1722} 1723 1724static int 1725witness_thread_has_locks(struct thread *td) 1726{ 1727 1728 return (td->td_sleeplocks != NULL); 1729} 1730 1731static int 1732witness_proc_has_locks(struct proc *p) 1733{ 1734 struct thread *td; 1735 1736 FOREACH_THREAD_IN_PROC(p, td) { 1737 if (witness_thread_has_locks(td)) 1738 return (1); 1739 } 1740 return (0); 1741} 1742 1743int 1744witness_list_locks(struct lock_list_entry **lock_list) 1745{ 1746 struct lock_list_entry *lle; 1747 int i, nheld; 1748 1749 nheld = 0; 1750 for (lle = *lock_list; lle != NULL; lle = lle->ll_next) 1751 for (i = lle->ll_count - 1; i >= 0; i--) { 1752 witness_list_lock(&lle->ll_children[i]); 1753 nheld++; 1754 } 1755 return (nheld); 1756} 1757 1758/* 1759 * This is a bit risky at best. We call this function when we have timed 1760 * out acquiring a spin lock, and we assume that the other CPU is stuck 1761 * with this lock held. So, we go groveling around in the other CPU's 1762 * per-cpu data to try to find the lock instance for this spin lock to 1763 * see when it was last acquired. 1764 */ 1765void 1766witness_display_spinlock(struct lock_object *lock, struct thread *owner) 1767{ 1768 struct lock_instance *instance; 1769 struct pcpu *pc; 1770 1771 if (owner->td_critnest == 0 || owner->td_oncpu == NOCPU) 1772 return; 1773 pc = pcpu_find(owner->td_oncpu); 1774 instance = find_instance(pc->pc_spinlocks, lock); 1775 if (instance != NULL) 1776 witness_list_lock(instance); 1777} 1778 1779void 1780witness_save(struct lock_object *lock, const char **filep, int *linep) 1781{ 1782 struct lock_instance *instance; 1783 1784 KASSERT(!witness_cold, ("%s: witness_cold", __func__)); 1785 if (lock->lo_witness == NULL || witness_watch == 0 || panicstr != NULL) 1786 return; 1787 if ((lock->lo_class->lc_flags & LC_SLEEPLOCK) == 0) 1788 panic("%s: lock (%s) %s is not a sleep lock", __func__, 1789 lock->lo_class->lc_name, lock->lo_name); 1790 instance = find_instance(curthread->td_sleeplocks, lock); 1791 if (instance == NULL) 1792 panic("%s: lock (%s) %s not locked", __func__, 1793 lock->lo_class->lc_name, lock->lo_name); 1794 *filep = instance->li_file; 1795 *linep = instance->li_line; 1796} 1797 1798void 1799witness_restore(struct lock_object *lock, const char *file, int line) 1800{ 1801 struct lock_instance *instance; 1802 1803 KASSERT(!witness_cold, ("%s: witness_cold", __func__)); 1804 if (lock->lo_witness == NULL || witness_watch == 0 || panicstr != NULL) 1805 return; 1806 if ((lock->lo_class->lc_flags & LC_SLEEPLOCK) == 0) 1807 panic("%s: lock (%s) %s is not a sleep lock", __func__, 1808 lock->lo_class->lc_name, lock->lo_name); 1809 instance = find_instance(curthread->td_sleeplocks, lock); 1810 if (instance == NULL) 1811 panic("%s: lock (%s) %s not locked", __func__, 1812 lock->lo_class->lc_name, lock->lo_name); 1813 lock->lo_witness->w_file = file; 1814 lock->lo_witness->w_line = line; 1815 instance->li_file = file; 1816 instance->li_line = line; 1817} 1818 1819void 1820witness_assert(struct lock_object *lock, int flags, const char *file, int line) 1821{ 1822#ifdef INVARIANT_SUPPORT 1823 struct lock_instance *instance; 1824 1825 if (lock->lo_witness == NULL || witness_watch == 0 || panicstr != NULL) 1826 return; 1827 if ((lock->lo_class->lc_flags & LC_SLEEPLOCK) != 0) 1828 instance = find_instance(curthread->td_sleeplocks, lock); 1829 else if ((lock->lo_class->lc_flags & LC_SPINLOCK) != 0) 1830 instance = find_instance(PCPU_GET(spinlocks), lock); 1831 else { 1832 panic("Lock (%s) %s is not sleep or spin!", 1833 lock->lo_class->lc_name, lock->lo_name); 1834 } 1835 file = fixup_filename(file); 1836 switch (flags) { 1837 case LA_UNLOCKED: 1838 if (instance != NULL) 1839 panic("Lock (%s) %s locked @ %s:%d.", 1840 lock->lo_class->lc_name, lock->lo_name, file, line); 1841 break; 1842 case LA_LOCKED: 1843 case LA_LOCKED | LA_RECURSED: 1844 case LA_LOCKED | LA_NOTRECURSED: 1845 case LA_SLOCKED: 1846 case LA_SLOCKED | LA_RECURSED: 1847 case LA_SLOCKED | LA_NOTRECURSED: 1848 case LA_XLOCKED: 1849 case LA_XLOCKED | LA_RECURSED: 1850 case LA_XLOCKED | LA_NOTRECURSED: 1851 if (instance == NULL) { 1852 panic("Lock (%s) %s not locked @ %s:%d.", 1853 lock->lo_class->lc_name, lock->lo_name, file, line); 1854 break; 1855 } 1856 if ((flags & LA_XLOCKED) != 0 && 1857 (instance->li_flags & LI_EXCLUSIVE) == 0) 1858 panic("Lock (%s) %s not exclusively locked @ %s:%d.", 1859 lock->lo_class->lc_name, lock->lo_name, file, line); 1860 if ((flags & LA_SLOCKED) != 0 && 1861 (instance->li_flags & LI_EXCLUSIVE) != 0) 1862 panic("Lock (%s) %s exclusively locked @ %s:%d.", 1863 lock->lo_class->lc_name, lock->lo_name, file, line); 1864 if ((flags & LA_RECURSED) != 0 && 1865 (instance->li_flags & LI_RECURSEMASK) == 0) 1866 panic("Lock (%s) %s not recursed @ %s:%d.", 1867 lock->lo_class->lc_name, lock->lo_name, file, line); 1868 if ((flags & LA_NOTRECURSED) != 0 && 1869 (instance->li_flags & LI_RECURSEMASK) != 0) 1870 panic("Lock (%s) %s recursed @ %s:%d.", 1871 lock->lo_class->lc_name, lock->lo_name, file, line); 1872 break; 1873 default: 1874 panic("Invalid lock assertion at %s:%d.", file, line); 1875 1876 } 1877#endif /* INVARIANT_SUPPORT */ 1878} 1879 1880#ifdef DDB 1881static void 1882witness_list(struct thread *td) 1883{ 1884 1885 KASSERT(!witness_cold, ("%s: witness_cold", __func__)); 1886 KASSERT(kdb_active, ("%s: not in the debugger", __func__)); 1887 1888 if (witness_watch == 0) 1889 return; 1890 1891 witness_list_locks(&td->td_sleeplocks); 1892 1893 /* 1894 * We only handle spinlocks if td == curthread. This is somewhat broken 1895 * if td is currently executing on some other CPU and holds spin locks 1896 * as we won't display those locks. If we had a MI way of getting 1897 * the per-cpu data for a given cpu then we could use 1898 * td->td_oncpu to get the list of spinlocks for this thread 1899 * and "fix" this. 1900 * 1901 * That still wouldn't really fix this unless we locked sched_lock 1902 * or stopped the other CPU to make sure it wasn't changing the list 1903 * out from under us. It is probably best to just not try to handle 1904 * threads on other CPU's for now. 1905 */ 1906 if (td == curthread && PCPU_GET(spinlocks) != NULL) 1907 witness_list_locks(PCPU_PTR(spinlocks)); 1908} 1909 1910DB_SHOW_COMMAND(locks, db_witness_list) 1911{ 1912 struct thread *td; 1913 pid_t pid; 1914 struct proc *p; 1915 1916 if (have_addr) { 1917 pid = (addr % 16) + ((addr >> 4) % 16) * 10 + 1918 ((addr >> 8) % 16) * 100 + ((addr >> 12) % 16) * 1000 + 1919 ((addr >> 16) % 16) * 10000; 1920 /* sx_slock(&allproc_lock); */ 1921 FOREACH_PROC_IN_SYSTEM(p) { 1922 if (p->p_pid == pid) 1923 break; 1924 } 1925 /* sx_sunlock(&allproc_lock); */ 1926 if (p == NULL) { 1927 db_printf("pid %d not found\n", pid); 1928 return; 1929 } 1930 FOREACH_THREAD_IN_PROC(p, td) { 1931 witness_list(td); 1932 } 1933 } else { 1934 td = curthread; 1935 witness_list(td); 1936 } 1937} 1938 1939DB_SHOW_COMMAND(alllocks, db_witness_list_all) 1940{ 1941 struct thread *td; 1942 struct proc *p; 1943 1944 /* 1945 * It would be nice to list only threads and processes that actually 1946 * held sleep locks, but that information is currently not exported 1947 * by WITNESS. 1948 */ 1949 FOREACH_PROC_IN_SYSTEM(p) { 1950 if (!witness_proc_has_locks(p)) 1951 continue; 1952 FOREACH_THREAD_IN_PROC(p, td) { 1953 if (!witness_thread_has_locks(td)) 1954 continue; 1955 printf("Process %d (%s) thread %p (%d)\n", p->p_pid, 1956 p->p_comm, td, td->td_tid); 1957 witness_list(td); 1958 } 1959 } 1960} 1961 1962DB_SHOW_COMMAND(witness, db_witness_display) 1963{ 1964 1965 witness_display(db_printf); 1966} 1967#endif 1968