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("$FreeBSD$"); 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 1024 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 6 119 120 struct witness_child_list_entry; 121 122 struct 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 }; 137 138 struct 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 }; 143 144 STAILQ_HEAD(witness_list, witness); 145 146 #ifdef BLESSING 147 struct witness_blessed { 148 const char *b_lock1; 149 const char *b_lock2; 150 }; 151 #endif 152 153 struct witness_order_list_entry { 154 const char *w_name; 155 struct lock_class *w_class; 156 }; 157 158 #ifdef BLESSING 159 static int blessed(struct witness *, struct witness *); 160 #endif 161 static int depart(struct witness *w); 162 static struct witness *enroll(const char *description, 163 struct lock_class *lock_class); 164 static int insertchild(struct witness *parent, struct witness *child); 165 static int isitmychild(struct witness *parent, struct witness *child); 166 static int isitmydescendant(struct witness *parent, struct witness *child); 167 static int itismychild(struct witness *parent, struct witness *child); 168 static void removechild(struct witness *parent, struct witness *child); 169 static int sysctl_debug_witness_watch(SYSCTL_HANDLER_ARGS); 170 static const char *fixup_filename(const char *file); 171 static struct witness *witness_get(void); 172 static void witness_free(struct witness *m); 173 static struct witness_child_list_entry *witness_child_get(void); 174 static void witness_child_free(struct witness_child_list_entry *wcl); 175 static struct lock_list_entry *witness_lock_list_get(void); 176 static void witness_lock_list_free(struct lock_list_entry *lle); 177 static struct lock_instance *find_instance(struct lock_list_entry *lock_list, 178 struct lock_object *lock); 179 static void witness_list_lock(struct lock_instance *instance); 180 #ifdef DDB 181 static void witness_leveldescendents(struct witness *parent, int level); 182 static void witness_levelall(void); 183 static void witness_displaydescendants(void(*)(const char *fmt, ...), 184 struct witness *, int indent); 185 static void witness_display_list(void(*prnt)(const char *fmt, ...), 186 struct witness_list *list); 187 static void witness_display(void(*)(const char *fmt, ...)); 188 static void witness_list(struct thread *td); 189 #endif 190 191 SYSCTL_NODE(_debug, OID_AUTO, witness, CTLFLAG_RW, 0, "Witness Locking"); 192 193 /* 194 * If set to 0, witness is disabled. If set to a non-zero value, witness 195 * performs full lock order checking for all locks. At runtime, this 196 * value may be set to 0 to turn off witness. witness is not allowed be 197 * turned on once it is turned off, however. 198 */ 199 static int witness_watch = 1; 200 TUNABLE_INT("debug.witness.watch", &witness_watch); 201 SYSCTL_PROC(_debug_witness, OID_AUTO, watch, CTLFLAG_RW | CTLTYPE_INT, NULL, 0, 202 sysctl_debug_witness_watch, "I", "witness is watching lock operations"); 203 204 #ifdef KDB 205 /* 206 * When KDB is enabled and witness_kdb is set to 1, it will cause the system 207 * to drop into kdebug() when: 208 * - a lock heirarchy violation occurs 209 * - locks are held when going to sleep. 210 */ 211 #ifdef WITNESS_KDB 212 int witness_kdb = 1; 213 #else 214 int witness_kdb = 0; 215 #endif 216 TUNABLE_INT("debug.witness.kdb", &witness_kdb); 217 SYSCTL_INT(_debug_witness, OID_AUTO, kdb, CTLFLAG_RW, &witness_kdb, 0, ""); 218 219 /* 220 * When KDB is enabled and witness_trace is set to 1, it will cause the system 221 * to print a stack trace: 222 * - a lock heirarchy violation occurs 223 * - locks are held when going to sleep. 224 */ 225 int witness_trace = 1; 226 TUNABLE_INT("debug.witness.trace", &witness_trace); 227 SYSCTL_INT(_debug_witness, OID_AUTO, trace, CTLFLAG_RW, &witness_trace, 0, ""); 228 #endif /* KDB */ 229 230 #ifdef WITNESS_SKIPSPIN 231 int witness_skipspin = 1; 232 #else 233 int witness_skipspin = 0; 234 #endif 235 TUNABLE_INT("debug.witness.skipspin", &witness_skipspin); 236 SYSCTL_INT(_debug_witness, OID_AUTO, skipspin, CTLFLAG_RDTUN, 237 &witness_skipspin, 0, ""); 238 239 static struct mtx w_mtx; 240 static struct witness_list w_free = STAILQ_HEAD_INITIALIZER(w_free); 241 static struct witness_list w_all = STAILQ_HEAD_INITIALIZER(w_all); 242 static struct witness_list w_spin = STAILQ_HEAD_INITIALIZER(w_spin); 243 static struct witness_list w_sleep = STAILQ_HEAD_INITIALIZER(w_sleep); 244 static struct witness_child_list_entry *w_child_free = NULL; 245 static struct lock_list_entry *w_lock_list_free = NULL; 246 247 static int w_free_cnt, w_spin_cnt, w_sleep_cnt, w_child_free_cnt, w_child_cnt; 248 SYSCTL_INT(_debug_witness, OID_AUTO, free_cnt, CTLFLAG_RD, &w_free_cnt, 0, ""); 249 SYSCTL_INT(_debug_witness, OID_AUTO, spin_cnt, CTLFLAG_RD, &w_spin_cnt, 0, ""); 250 SYSCTL_INT(_debug_witness, OID_AUTO, sleep_cnt, CTLFLAG_RD, &w_sleep_cnt, 0, 251 ""); 252 SYSCTL_INT(_debug_witness, OID_AUTO, child_free_cnt, CTLFLAG_RD, 253 &w_child_free_cnt, 0, ""); 254 SYSCTL_INT(_debug_witness, OID_AUTO, child_cnt, CTLFLAG_RD, &w_child_cnt, 0, 255 ""); 256 257 static struct witness w_data[WITNESS_COUNT]; 258 static struct witness_child_list_entry w_childdata[WITNESS_CHILDCOUNT]; 259 static struct lock_list_entry w_locklistdata[LOCK_CHILDCOUNT]; 260 261 static struct witness_order_list_entry order_lists[] = { 262 /* 263 * sx locks 264 */ 265 { "proctree", &lock_class_sx }, 266 { "allproc", &lock_class_sx }, 267 { NULL, NULL }, 268 /* 269 * Various mutexes 270 */ 271 { "Giant", &lock_class_mtx_sleep }, 272 { "filedesc structure", &lock_class_mtx_sleep }, 273 { "pipe mutex", &lock_class_mtx_sleep }, 274 { "sigio lock", &lock_class_mtx_sleep }, 275 { "process group", &lock_class_mtx_sleep }, 276 { "process lock", &lock_class_mtx_sleep }, 277 { "session", &lock_class_mtx_sleep }, 278 { "uidinfo hash", &lock_class_mtx_sleep }, 279 { "uidinfo struct", &lock_class_mtx_sleep }, 280 { "allprison", &lock_class_mtx_sleep }, 281 { NULL, NULL }, 282 /* 283 * Sockets 284 */ 285 { "filedesc structure", &lock_class_mtx_sleep }, 286 { "accept", &lock_class_mtx_sleep }, 287 { "so_snd", &lock_class_mtx_sleep }, 288 { "so_rcv", &lock_class_mtx_sleep }, 289 { "sellck", &lock_class_mtx_sleep }, 290 { NULL, NULL }, 291 /* 292 * Routing 293 */ 294 { "so_rcv", &lock_class_mtx_sleep }, 295 { "radix node head", &lock_class_mtx_sleep }, 296 { "rtentry", &lock_class_mtx_sleep }, 297 { "ifaddr", &lock_class_mtx_sleep }, 298 { NULL, NULL }, 299 /* 300 * Multicast - protocol locks before interface locks, after UDP locks. 301 */ 302 { "udpinp", &lock_class_mtx_sleep }, 303 { "in_multi_mtx", &lock_class_mtx_sleep }, 304 { "igmp_mtx", &lock_class_mtx_sleep }, 305 { "if_addr_mtx", &lock_class_mtx_sleep }, 306 { NULL, NULL }, 307 /* 308 * UNIX Domain Sockets 309 */ 310 { "unp", &lock_class_mtx_sleep }, 311 { "so_snd", &lock_class_mtx_sleep }, 312 { NULL, NULL }, 313 /* 314 * UDP/IP 315 */ 316 { "udp", &lock_class_mtx_sleep }, 317 { "udpinp", &lock_class_mtx_sleep }, 318 { "so_snd", &lock_class_mtx_sleep }, 319 { NULL, NULL }, 320 /* 321 * TCP/IP 322 */ 323 { "tcp", &lock_class_mtx_sleep }, 324 { "tcpinp", &lock_class_mtx_sleep }, 325 { "so_snd", &lock_class_mtx_sleep }, 326 { NULL, NULL }, 327 /* 328 * SLIP 329 */ 330 { "slip_mtx", &lock_class_mtx_sleep }, 331 { "slip sc_mtx", &lock_class_mtx_sleep }, 332 { NULL, NULL }, 333 /* 334 * netatalk 335 */ 336 { "ddp_list_mtx", &lock_class_mtx_sleep }, 337 { "ddp_mtx", &lock_class_mtx_sleep }, 338 { NULL, NULL }, 339 /* 340 * BPF 341 */ 342 { "bpf global lock", &lock_class_mtx_sleep }, 343 { "bpf interface lock", &lock_class_mtx_sleep }, 344 { "bpf cdev lock", &lock_class_mtx_sleep }, 345 { NULL, NULL }, 346 /* 347 * NFS server 348 */ 349 { "nfsd_mtx", &lock_class_mtx_sleep }, 350 { "so_snd", &lock_class_mtx_sleep }, 351 { NULL, NULL }, 352 /* 353 * CDEV 354 */ 355 { "system map", &lock_class_mtx_sleep }, 356 { "vm page queue mutex", &lock_class_mtx_sleep }, 357 { "vnode interlock", &lock_class_mtx_sleep }, 358 { "cdev", &lock_class_mtx_sleep }, 359 { NULL, NULL }, 360 /* 361 * spin locks 362 */ 363 #ifdef SMP 364 { "ap boot", &lock_class_mtx_spin }, 365 #endif 366 { "rm.mutex_mtx", &lock_class_mtx_spin }, 367 { "sio", &lock_class_mtx_spin }, 368 #ifdef __i386__ 369 { "cy", &lock_class_mtx_spin }, 370 #endif 371 { "uart_hwmtx", &lock_class_mtx_spin }, 372 { "sabtty", &lock_class_mtx_spin }, 373 { "zstty", &lock_class_mtx_spin }, 374 { "ng_node", &lock_class_mtx_spin }, 375 { "ng_worklist", &lock_class_mtx_spin }, 376 { "taskqueue_fast", &lock_class_mtx_spin }, 377 { "intr table", &lock_class_mtx_spin }, 378 { "ithread table lock", &lock_class_mtx_spin }, 379 { "sleepq chain", &lock_class_mtx_spin }, 380 { "sched lock", &lock_class_mtx_spin }, 381 { "turnstile chain", &lock_class_mtx_spin }, 382 { "td_contested", &lock_class_mtx_spin }, 383 { "callout", &lock_class_mtx_spin }, 384 { "entropy harvest mutex", &lock_class_mtx_spin }, 385 /* 386 * leaf locks 387 */ 388 { "allpmaps", &lock_class_mtx_spin }, 389 { "vm page queue free mutex", &lock_class_mtx_spin }, 390 { "icu", &lock_class_mtx_spin }, 391 #ifdef SMP 392 { "smp rendezvous", &lock_class_mtx_spin }, 393 #if defined(__i386__) || defined(__amd64__) 394 { "tlb", &lock_class_mtx_spin }, 395 #endif 396 #ifdef __sparc64__ 397 { "ipi", &lock_class_mtx_spin }, 398 { "rtc_mtx", &lock_class_mtx_spin }, 399 #endif 400 #endif 401 { "clk", &lock_class_mtx_spin }, 402 { "mutex profiling lock", &lock_class_mtx_spin }, 403 { "kse zombie lock", &lock_class_mtx_spin }, 404 { "ALD Queue", &lock_class_mtx_spin }, 405 #ifdef __ia64__ 406 { "MCA spin lock", &lock_class_mtx_spin }, 407 #endif 408 #if defined(__i386__) || defined(__amd64__) 409 { "pcicfg", &lock_class_mtx_spin }, 410 { "NDIS thread lock", &lock_class_mtx_spin }, 411 #endif 412 { "tw_osl_io_lock", &lock_class_mtx_spin }, 413 { "tw_osl_q_lock", &lock_class_mtx_spin }, 414 { "tw_cl_io_lock", &lock_class_mtx_spin }, 415 { "tw_cl_intr_lock", &lock_class_mtx_spin }, 416 { "tw_cl_gen_lock", &lock_class_mtx_spin }, 417 { NULL, NULL }, 418 { NULL, NULL } 419 }; 420 421 #ifdef BLESSING 422 /* 423 * Pairs of locks which have been blessed 424 * Don't complain about order problems with blessed locks 425 */ 426 static struct witness_blessed blessed_list[] = { 427 }; 428 static int blessed_count = 429 sizeof(blessed_list) / sizeof(struct witness_blessed); 430 #endif 431 432 /* 433 * List of all locks in the system. 434 */ 435 TAILQ_HEAD(, lock_object) all_locks = TAILQ_HEAD_INITIALIZER(all_locks); 436 437 static struct mtx all_mtx = { 438 { &lock_class_mtx_sleep, /* mtx_object.lo_class */ 439 "All locks list", /* mtx_object.lo_name */ 440 "All locks list", /* mtx_object.lo_type */ 441 LO_INITIALIZED, /* mtx_object.lo_flags */ 442 { NULL, NULL }, /* mtx_object.lo_list */ 443 NULL }, /* mtx_object.lo_witness */ 444 MTX_UNOWNED, 0 /* mtx_lock, mtx_recurse */ 445 }; 446 447 /* 448 * This global is set to 0 once it becomes safe to use the witness code. 449 */ 450 static int witness_cold = 1; 451 452 /* 453 * Global variables for book keeping. 454 */ 455 static int lock_cur_cnt; 456 static int lock_max_cnt; 457 458 /* 459 * The WITNESS-enabled diagnostic code. 460 */ 461 static void 462 witness_initialize(void *dummy __unused) 463 { 464 struct lock_object *lock; 465 struct witness_order_list_entry *order; 466 struct witness *w, *w1; 467 int i; 468 469 /* 470 * We have to release Giant before initializing its witness 471 * structure so that WITNESS doesn't get confused. 472 */ 473 mtx_unlock(&Giant); 474 mtx_assert(&Giant, MA_NOTOWNED); 475 476 CTR1(KTR_WITNESS, "%s: initializing witness", __func__); 477 TAILQ_INSERT_HEAD(&all_locks, &all_mtx.mtx_object, lo_list); 478 mtx_init(&w_mtx, "witness lock", NULL, MTX_SPIN | MTX_QUIET | 479 MTX_NOWITNESS); 480 for (i = 0; i < WITNESS_COUNT; i++) 481 witness_free(&w_data[i]); 482 for (i = 0; i < WITNESS_CHILDCOUNT; i++) 483 witness_child_free(&w_childdata[i]); 484 for (i = 0; i < LOCK_CHILDCOUNT; i++) 485 witness_lock_list_free(&w_locklistdata[i]); 486 487 /* First add in all the specified order lists. */ 488 for (order = order_lists; order->w_name != NULL; order++) { 489 w = enroll(order->w_name, order->w_class); 490 if (w == NULL) 491 continue; 492 w->w_file = "order list"; 493 for (order++; order->w_name != NULL; order++) { 494 w1 = enroll(order->w_name, order->w_class); 495 if (w1 == NULL) 496 continue; 497 w1->w_file = "order list"; 498 if (!itismychild(w, w1)) 499 panic("Not enough memory for static orders!"); 500 w = w1; 501 } 502 } 503 504 /* Iterate through all locks and add them to witness. */ 505 mtx_lock(&all_mtx); 506 TAILQ_FOREACH(lock, &all_locks, lo_list) { 507 if (lock->lo_flags & LO_WITNESS) 508 lock->lo_witness = enroll(lock->lo_type, 509 lock->lo_class); 510 else 511 lock->lo_witness = NULL; 512 } 513 mtx_unlock(&all_mtx); 514 515 /* Mark the witness code as being ready for use. */ 516 atomic_store_rel_int(&witness_cold, 0); 517 518 mtx_lock(&Giant); 519 } 520 SYSINIT(witness_init, SI_SUB_WITNESS, SI_ORDER_FIRST, witness_initialize, NULL) 521 522 static int 523 sysctl_debug_witness_watch(SYSCTL_HANDLER_ARGS) 524 { 525 int error, value; 526 527 value = witness_watch; 528 error = sysctl_handle_int(oidp, &value, 0, req); 529 if (error != 0 || req->newptr == NULL) 530 return (error); 531 error = suser(req->td); 532 if (error != 0) 533 return (error); 534 if (value == witness_watch) 535 return (0); 536 if (value != 0) 537 return (EINVAL); 538 witness_watch = 0; 539 return (0); 540 } 541 542 void 543 witness_init(struct lock_object *lock) 544 { 545 struct lock_class *class; 546 547 class = lock->lo_class; 548 if (lock->lo_flags & LO_INITIALIZED) 549 panic("%s: lock (%s) %s is already initialized", __func__, 550 class->lc_name, lock->lo_name); 551 if ((lock->lo_flags & LO_RECURSABLE) != 0 && 552 (class->lc_flags & LC_RECURSABLE) == 0) 553 panic("%s: lock (%s) %s can not be recursable", __func__, 554 class->lc_name, lock->lo_name); 555 if ((lock->lo_flags & LO_SLEEPABLE) != 0 && 556 (class->lc_flags & LC_SLEEPABLE) == 0) 557 panic("%s: lock (%s) %s can not be sleepable", __func__, 558 class->lc_name, lock->lo_name); 559 if ((lock->lo_flags & LO_UPGRADABLE) != 0 && 560 (class->lc_flags & LC_UPGRADABLE) == 0) 561 panic("%s: lock (%s) %s can not be upgradable", __func__, 562 class->lc_name, lock->lo_name); 563 564 mtx_lock(&all_mtx); 565 TAILQ_INSERT_TAIL(&all_locks, lock, lo_list); 566 lock->lo_flags |= LO_INITIALIZED; 567 lock_cur_cnt++; 568 if (lock_cur_cnt > lock_max_cnt) 569 lock_max_cnt = lock_cur_cnt; 570 mtx_unlock(&all_mtx); 571 if (!witness_cold && witness_watch != 0 && panicstr == NULL && 572 (lock->lo_flags & LO_WITNESS) != 0) 573 lock->lo_witness = enroll(lock->lo_type, class); 574 else 575 lock->lo_witness = NULL; 576 } 577 578 void 579 witness_destroy(struct lock_object *lock) 580 { 581 struct witness *w; 582 583 if (witness_cold) 584 panic("lock (%s) %s destroyed while witness_cold", 585 lock->lo_class->lc_name, lock->lo_name); 586 if ((lock->lo_flags & LO_INITIALIZED) == 0) 587 panic("%s: lock (%s) %s is not initialized", __func__, 588 lock->lo_class->lc_name, lock->lo_name); 589 590 /* XXX: need to verify that no one holds the lock */ 591 w = lock->lo_witness; 592 if (w != NULL) { 593 mtx_lock_spin(&w_mtx); 594 MPASS(w->w_refcount > 0); 595 w->w_refcount--; 596 597 /* 598 * Lock is already released if we have an allocation failure 599 * and depart() fails. 600 */ 601 if (w->w_refcount != 0 || depart(w)) 602 mtx_unlock_spin(&w_mtx); 603 } 604 605 mtx_lock(&all_mtx); 606 lock_cur_cnt--; 607 TAILQ_REMOVE(&all_locks, lock, lo_list); 608 lock->lo_flags &= ~LO_INITIALIZED; 609 mtx_unlock(&all_mtx); 610 } 611 612 #ifdef DDB 613 static void 614 witness_levelall (void) 615 { 616 struct witness_list *list; 617 struct witness *w, *w1; 618 619 /* 620 * First clear all levels. 621 */ 622 STAILQ_FOREACH(w, &w_all, w_list) { 623 w->w_level = 0; 624 } 625 626 /* 627 * Look for locks with no parent and level all their descendants. 628 */ 629 STAILQ_FOREACH(w, &w_all, w_list) { 630 /* 631 * This is just an optimization, technically we could get 632 * away just walking the all list each time. 633 */ 634 if (w->w_class->lc_flags & LC_SLEEPLOCK) 635 list = &w_sleep; 636 else 637 list = &w_spin; 638 STAILQ_FOREACH(w1, list, w_typelist) { 639 if (isitmychild(w1, w)) 640 goto skip; 641 } 642 witness_leveldescendents(w, 0); 643 skip: 644 ; /* silence GCC 3.x */ 645 } 646 } 647 648 static void 649 witness_leveldescendents(struct witness *parent, int level) 650 { 651 struct witness_child_list_entry *wcl; 652 int i; 653 654 if (parent->w_level < level) 655 parent->w_level = level; 656 level++; 657 for (wcl = parent->w_children; wcl != NULL; wcl = wcl->wcl_next) 658 for (i = 0; i < wcl->wcl_count; i++) 659 witness_leveldescendents(wcl->wcl_children[i], level); 660 } 661 662 static void 663 witness_displaydescendants(void(*prnt)(const char *fmt, ...), 664 struct witness *parent, int indent) 665 { 666 struct witness_child_list_entry *wcl; 667 int i, level; 668 669 level = parent->w_level; 670 prnt("%-2d", level); 671 for (i = 0; i < indent; i++) 672 prnt(" "); 673 if (parent->w_refcount > 0) 674 prnt("%s", parent->w_name); 675 else 676 prnt("(dead)"); 677 if (parent->w_displayed) { 678 prnt(" -- (already displayed)\n"); 679 return; 680 } 681 parent->w_displayed = 1; 682 if (parent->w_refcount > 0) { 683 if (parent->w_file != NULL) 684 prnt(" -- last acquired @ %s:%d", parent->w_file, 685 parent->w_line); 686 } 687 prnt("\n"); 688 for (wcl = parent->w_children; wcl != NULL; wcl = wcl->wcl_next) 689 for (i = 0; i < wcl->wcl_count; i++) 690 witness_displaydescendants(prnt, 691 wcl->wcl_children[i], indent + 1); 692 } 693 694 static void 695 witness_display_list(void(*prnt)(const char *fmt, ...), 696 struct witness_list *list) 697 { 698 struct witness *w; 699 700 STAILQ_FOREACH(w, list, w_typelist) { 701 if (w->w_file == NULL || w->w_level > 0) 702 continue; 703 /* 704 * This lock has no anscestors, display its descendants. 705 */ 706 witness_displaydescendants(prnt, w, 0); 707 } 708 } 709 710 static void 711 witness_display(void(*prnt)(const char *fmt, ...)) 712 { 713 struct witness *w; 714 715 KASSERT(!witness_cold, ("%s: witness_cold", __func__)); 716 witness_levelall(); 717 718 /* Clear all the displayed flags. */ 719 STAILQ_FOREACH(w, &w_all, w_list) { 720 w->w_displayed = 0; 721 } 722 723 /* 724 * First, handle sleep locks which have been acquired at least 725 * once. 726 */ 727 prnt("Sleep locks:\n"); 728 witness_display_list(prnt, &w_sleep); 729 730 /* 731 * Now do spin locks which have been acquired at least once. 732 */ 733 prnt("\nSpin locks:\n"); 734 witness_display_list(prnt, &w_spin); 735 736 /* 737 * Finally, any locks which have not been acquired yet. 738 */ 739 prnt("\nLocks which were never acquired:\n"); 740 STAILQ_FOREACH(w, &w_all, w_list) { 741 if (w->w_file != NULL || w->w_refcount == 0) 742 continue; 743 prnt("%s\n", w->w_name); 744 } 745 } 746 #endif /* DDB */ 747 748 /* Trim useless garbage from filenames. */ 749 static const char * 750 fixup_filename(const char *file) 751 { 752 753 if (file == NULL) 754 return (NULL); 755 while (strncmp(file, "../", 3) == 0) 756 file += 3; 757 return (file); 758 } 759 760 int 761 witness_defineorder(struct lock_object *lock1, struct lock_object *lock2) 762 { 763 764 if (witness_watch == 0 || panicstr != NULL) 765 return (0); 766 767 /* Require locks that witness knows about. */ 768 if (lock1 == NULL || lock1->lo_witness == NULL || lock2 == NULL || 769 lock2->lo_witness == NULL) 770 return (EINVAL); 771 772 MPASS(!mtx_owned(&w_mtx)); 773 mtx_lock_spin(&w_mtx); 774 775 /* 776 * If we already have either an explicit or implied lock order that 777 * is the other way around, then return an error. 778 */ 779 if (isitmydescendant(lock2->lo_witness, lock1->lo_witness)) { 780 mtx_unlock_spin(&w_mtx); 781 return (EDOOFUS); 782 } 783 784 /* Try to add the new order. */ 785 CTR3(KTR_WITNESS, "%s: adding %s as a child of %s", __func__, 786 lock2->lo_type, lock1->lo_type); 787 if (!itismychild(lock1->lo_witness, lock2->lo_witness)) 788 return (ENOMEM); 789 mtx_unlock_spin(&w_mtx); 790 return (0); 791 } 792 793 void 794 witness_checkorder(struct lock_object *lock, int flags, const char *file, 795 int line) 796 { 797 struct lock_list_entry **lock_list, *lle; 798 struct lock_instance *lock1, *lock2; 799 struct lock_class *class; 800 struct witness *w, *w1; 801 struct thread *td; 802 int i, j; 803 804 if (witness_cold || witness_watch == 0 || lock->lo_witness == NULL || 805 panicstr != NULL) 806 return; 807 808 /* 809 * Try locks do not block if they fail to acquire the lock, thus 810 * there is no danger of deadlocks or of switching while holding a 811 * spin lock if we acquire a lock via a try operation. This 812 * function shouldn't even be called for try locks, so panic if 813 * that happens. 814 */ 815 if (flags & LOP_TRYLOCK) 816 panic("%s should not be called for try lock operations", 817 __func__); 818 819 w = lock->lo_witness; 820 class = lock->lo_class; 821 td = curthread; 822 file = fixup_filename(file); 823 824 if (class->lc_flags & LC_SLEEPLOCK) { 825 /* 826 * Since spin locks include a critical section, this check 827 * implicitly enforces a lock order of all sleep locks before 828 * all spin locks. 829 */ 830 if (td->td_critnest != 0 && !kdb_active) 831 panic("blockable sleep lock (%s) %s @ %s:%d", 832 class->lc_name, lock->lo_name, file, line); 833 834 /* 835 * If this is the first lock acquired then just return as 836 * no order checking is needed. 837 */ 838 if (td->td_sleeplocks == NULL) 839 return; 840 lock_list = &td->td_sleeplocks; 841 } else { 842 /* 843 * If this is the first lock, just return as no order 844 * checking is needed. We check this in both if clauses 845 * here as unifying the check would require us to use a 846 * critical section to ensure we don't migrate while doing 847 * the check. Note that if this is not the first lock, we 848 * are already in a critical section and are safe for the 849 * rest of the check. 850 */ 851 if (PCPU_GET(spinlocks) == NULL) 852 return; 853 lock_list = PCPU_PTR(spinlocks); 854 } 855 856 /* 857 * Check to see if we are recursing on a lock we already own. If 858 * so, make sure that we don't mismatch exclusive and shared lock 859 * acquires. 860 */ 861 lock1 = find_instance(*lock_list, lock); 862 if (lock1 != NULL) { 863 if ((lock1->li_flags & LI_EXCLUSIVE) != 0 && 864 (flags & LOP_EXCLUSIVE) == 0) { 865 printf("shared lock of (%s) %s @ %s:%d\n", 866 class->lc_name, lock->lo_name, file, line); 867 printf("while exclusively locked from %s:%d\n", 868 lock1->li_file, lock1->li_line); 869 panic("share->excl"); 870 } 871 if ((lock1->li_flags & LI_EXCLUSIVE) == 0 && 872 (flags & LOP_EXCLUSIVE) != 0) { 873 printf("exclusive lock of (%s) %s @ %s:%d\n", 874 class->lc_name, lock->lo_name, file, line); 875 printf("while share locked from %s:%d\n", 876 lock1->li_file, lock1->li_line); 877 panic("excl->share"); 878 } 879 return; 880 } 881 882 /* 883 * Try locks do not block if they fail to acquire the lock, thus 884 * there is no danger of deadlocks or of switching while holding a 885 * spin lock if we acquire a lock via a try operation. 886 */ 887 if (flags & LOP_TRYLOCK) 888 return; 889 890 /* 891 * Check for duplicate locks of the same type. Note that we only 892 * have to check for this on the last lock we just acquired. Any 893 * other cases will be caught as lock order violations. 894 */ 895 lock1 = &(*lock_list)->ll_children[(*lock_list)->ll_count - 1]; 896 w1 = lock1->li_lock->lo_witness; 897 if (w1 == w) { 898 if (w->w_same_squawked || (lock->lo_flags & LO_DUPOK) || 899 (flags & LOP_DUPOK)) 900 return; 901 w->w_same_squawked = 1; 902 printf("acquiring duplicate lock of same type: \"%s\"\n", 903 lock->lo_type); 904 printf(" 1st %s @ %s:%d\n", lock1->li_lock->lo_name, 905 lock1->li_file, lock1->li_line); 906 printf(" 2nd %s @ %s:%d\n", lock->lo_name, file, line); 907 #ifdef KDB 908 goto debugger; 909 #else 910 return; 911 #endif 912 } 913 MPASS(!mtx_owned(&w_mtx)); 914 mtx_lock_spin(&w_mtx); 915 /* 916 * If we know that the the lock we are acquiring comes after 917 * the lock we most recently acquired in the lock order tree, 918 * then there is no need for any further checks. 919 */ 920 if (isitmychild(w1, w)) { 921 mtx_unlock_spin(&w_mtx); 922 return; 923 } 924 for (j = 0, lle = *lock_list; lle != NULL; lle = lle->ll_next) { 925 for (i = lle->ll_count - 1; i >= 0; i--, j++) { 926 927 MPASS(j < WITNESS_COUNT); 928 lock1 = &lle->ll_children[i]; 929 w1 = lock1->li_lock->lo_witness; 930 931 /* 932 * If this lock doesn't undergo witness checking, 933 * then skip it. 934 */ 935 if (w1 == NULL) { 936 KASSERT((lock1->li_lock->lo_flags & LO_WITNESS) == 0, 937 ("lock missing witness structure")); 938 continue; 939 } 940 /* 941 * If we are locking Giant and this is a sleepable 942 * lock, then skip it. 943 */ 944 if ((lock1->li_lock->lo_flags & LO_SLEEPABLE) != 0 && 945 lock == &Giant.mtx_object) 946 continue; 947 /* 948 * If we are locking a sleepable lock and this lock 949 * is Giant, then skip it. 950 */ 951 if ((lock->lo_flags & LO_SLEEPABLE) != 0 && 952 lock1->li_lock == &Giant.mtx_object) 953 continue; 954 /* 955 * If we are locking a sleepable lock and this lock 956 * isn't sleepable, we want to treat it as a lock 957 * order violation to enfore a general lock order of 958 * sleepable locks before non-sleepable locks. 959 */ 960 if (((lock->lo_flags & LO_SLEEPABLE) != 0 && 961 (lock1->li_lock->lo_flags & LO_SLEEPABLE) == 0)) 962 goto reversal; 963 /* 964 * If we are locking Giant and this is a non-sleepable 965 * lock, then treat it as a reversal. 966 */ 967 if ((lock1->li_lock->lo_flags & LO_SLEEPABLE) == 0 && 968 lock == &Giant.mtx_object) 969 goto reversal; 970 /* 971 * Check the lock order hierarchy for a reveresal. 972 */ 973 if (!isitmydescendant(w, w1)) 974 continue; 975 reversal: 976 /* 977 * We have a lock order violation, check to see if it 978 * is allowed or has already been yelled about. 979 */ 980 mtx_unlock_spin(&w_mtx); 981 #ifdef BLESSING 982 /* 983 * If the lock order is blessed, just bail. We don't 984 * look for other lock order violations though, which 985 * may be a bug. 986 */ 987 if (blessed(w, w1)) 988 return; 989 #endif 990 if (lock1->li_lock == &Giant.mtx_object) { 991 if (w1->w_Giant_squawked) 992 return; 993 else 994 w1->w_Giant_squawked = 1; 995 } else { 996 if (w1->w_other_squawked) 997 return; 998 else 999 w1->w_other_squawked = 1; 1000 } 1001 /* 1002 * Ok, yell about it. 1003 */ 1004 if (((lock->lo_flags & LO_SLEEPABLE) != 0 && 1005 (lock1->li_lock->lo_flags & LO_SLEEPABLE) == 0)) 1006 printf( 1007 "lock order reversal: (sleepable after non-sleepable)\n"); 1008 else if ((lock1->li_lock->lo_flags & LO_SLEEPABLE) == 0 1009 && lock == &Giant.mtx_object) 1010 printf( 1011 "lock order reversal: (Giant after non-sleepable)\n"); 1012 else 1013 printf("lock order reversal:\n"); 1014 /* 1015 * Try to locate an earlier lock with 1016 * witness w in our list. 1017 */ 1018 do { 1019 lock2 = &lle->ll_children[i]; 1020 MPASS(lock2->li_lock != NULL); 1021 if (lock2->li_lock->lo_witness == w) 1022 break; 1023 if (i == 0 && lle->ll_next != NULL) { 1024 lle = lle->ll_next; 1025 i = lle->ll_count - 1; 1026 MPASS(i >= 0 && i < LOCK_NCHILDREN); 1027 } else 1028 i--; 1029 } while (i >= 0); 1030 if (i < 0) { 1031 printf(" 1st %p %s (%s) @ %s:%d\n", 1032 lock1->li_lock, lock1->li_lock->lo_name, 1033 lock1->li_lock->lo_type, lock1->li_file, 1034 lock1->li_line); 1035 printf(" 2nd %p %s (%s) @ %s:%d\n", lock, 1036 lock->lo_name, lock->lo_type, file, line); 1037 } else { 1038 printf(" 1st %p %s (%s) @ %s:%d\n", 1039 lock2->li_lock, lock2->li_lock->lo_name, 1040 lock2->li_lock->lo_type, lock2->li_file, 1041 lock2->li_line); 1042 printf(" 2nd %p %s (%s) @ %s:%d\n", 1043 lock1->li_lock, lock1->li_lock->lo_name, 1044 lock1->li_lock->lo_type, lock1->li_file, 1045 lock1->li_line); 1046 printf(" 3rd %p %s (%s) @ %s:%d\n", lock, 1047 lock->lo_name, lock->lo_type, file, line); 1048 } 1049 #ifdef KDB 1050 goto debugger; 1051 #else 1052 return; 1053 #endif 1054 } 1055 } 1056 lock1 = &(*lock_list)->ll_children[(*lock_list)->ll_count - 1]; 1057 /* 1058 * If requested, build a new lock order. However, don't build a new 1059 * relationship between a sleepable lock and Giant if it is in the 1060 * wrong direction. The correct lock order is that sleepable locks 1061 * always come before Giant. 1062 */ 1063 if (flags & LOP_NEWORDER && 1064 !(lock1->li_lock == &Giant.mtx_object && 1065 (lock->lo_flags & LO_SLEEPABLE) != 0)) { 1066 CTR3(KTR_WITNESS, "%s: adding %s as a child of %s", __func__, 1067 lock->lo_type, lock1->li_lock->lo_type); 1068 if (!itismychild(lock1->li_lock->lo_witness, w)) 1069 /* Witness is dead. */ 1070 return; 1071 } 1072 mtx_unlock_spin(&w_mtx); 1073 return; 1074 1075 #ifdef KDB 1076 debugger: 1077 if (witness_trace) 1078 kdb_backtrace(); 1079 if (witness_kdb) 1080 kdb_enter(__func__); 1081 #endif 1082 } 1083 1084 void 1085 witness_lock(struct lock_object *lock, int flags, const char *file, int line) 1086 { 1087 struct lock_list_entry **lock_list, *lle; 1088 struct lock_instance *instance; 1089 struct witness *w; 1090 struct thread *td; 1091 1092 if (witness_cold || witness_watch == 0 || lock->lo_witness == NULL || 1093 panicstr != NULL) 1094 return; 1095 w = lock->lo_witness; 1096 td = curthread; 1097 file = fixup_filename(file); 1098 1099 /* Determine lock list for this lock. */ 1100 if (lock->lo_class->lc_flags & LC_SLEEPLOCK) 1101 lock_list = &td->td_sleeplocks; 1102 else 1103 lock_list = PCPU_PTR(spinlocks); 1104 1105 /* Check to see if we are recursing on a lock we already own. */ 1106 instance = find_instance(*lock_list, lock); 1107 if (instance != NULL) { 1108 instance->li_flags++; 1109 CTR4(KTR_WITNESS, "%s: pid %d recursed on %s r=%d", __func__, 1110 td->td_proc->p_pid, lock->lo_name, 1111 instance->li_flags & LI_RECURSEMASK); 1112 instance->li_file = file; 1113 instance->li_line = line; 1114 return; 1115 } 1116 1117 /* Update per-witness last file and line acquire. */ 1118 w->w_file = file; 1119 w->w_line = line; 1120 1121 /* Find the next open lock instance in the list and fill it. */ 1122 lle = *lock_list; 1123 if (lle == NULL || lle->ll_count == LOCK_NCHILDREN) { 1124 lle = witness_lock_list_get(); 1125 if (lle == NULL) 1126 return; 1127 lle->ll_next = *lock_list; 1128 CTR3(KTR_WITNESS, "%s: pid %d added lle %p", __func__, 1129 td->td_proc->p_pid, lle); 1130 *lock_list = lle; 1131 } 1132 instance = &lle->ll_children[lle->ll_count++]; 1133 instance->li_lock = lock; 1134 instance->li_line = line; 1135 instance->li_file = file; 1136 if ((flags & LOP_EXCLUSIVE) != 0) 1137 instance->li_flags = LI_EXCLUSIVE; 1138 else 1139 instance->li_flags = 0; 1140 CTR4(KTR_WITNESS, "%s: pid %d added %s as lle[%d]", __func__, 1141 td->td_proc->p_pid, lock->lo_name, lle->ll_count - 1); 1142 } 1143 1144 void 1145 witness_upgrade(struct lock_object *lock, int flags, const char *file, int line) 1146 { 1147 struct lock_instance *instance; 1148 struct lock_class *class; 1149 1150 KASSERT(!witness_cold, ("%s: witness_cold", __func__)); 1151 if (lock->lo_witness == NULL || witness_watch == 0 || panicstr != NULL) 1152 return; 1153 class = lock->lo_class; 1154 file = fixup_filename(file); 1155 if ((lock->lo_flags & LO_UPGRADABLE) == 0) 1156 panic("upgrade of non-upgradable lock (%s) %s @ %s:%d", 1157 class->lc_name, lock->lo_name, file, line); 1158 if ((flags & LOP_TRYLOCK) == 0) 1159 panic("non-try upgrade of lock (%s) %s @ %s:%d", class->lc_name, 1160 lock->lo_name, file, line); 1161 if ((lock->lo_class->lc_flags & LC_SLEEPLOCK) == 0) 1162 panic("upgrade of non-sleep lock (%s) %s @ %s:%d", 1163 class->lc_name, lock->lo_name, file, line); 1164 instance = find_instance(curthread->td_sleeplocks, lock); 1165 if (instance == NULL) 1166 panic("upgrade of unlocked lock (%s) %s @ %s:%d", 1167 class->lc_name, lock->lo_name, file, line); 1168 if ((instance->li_flags & LI_EXCLUSIVE) != 0) 1169 panic("upgrade of exclusive lock (%s) %s @ %s:%d", 1170 class->lc_name, lock->lo_name, file, line); 1171 if ((instance->li_flags & LI_RECURSEMASK) != 0) 1172 panic("upgrade of recursed lock (%s) %s r=%d @ %s:%d", 1173 class->lc_name, lock->lo_name, 1174 instance->li_flags & LI_RECURSEMASK, file, line); 1175 instance->li_flags |= LI_EXCLUSIVE; 1176 } 1177 1178 void 1179 witness_downgrade(struct lock_object *lock, int flags, const char *file, 1180 int line) 1181 { 1182 struct lock_instance *instance; 1183 struct lock_class *class; 1184 1185 KASSERT(!witness_cold, ("%s: witness_cold", __func__)); 1186 if (lock->lo_witness == NULL || witness_watch == 0 || panicstr != NULL) 1187 return; 1188 class = lock->lo_class; 1189 file = fixup_filename(file); 1190 if ((lock->lo_flags & LO_UPGRADABLE) == 0) 1191 panic("downgrade of non-upgradable lock (%s) %s @ %s:%d", 1192 class->lc_name, lock->lo_name, file, line); 1193 if ((lock->lo_class->lc_flags & LC_SLEEPLOCK) == 0) 1194 panic("downgrade of non-sleep lock (%s) %s @ %s:%d", 1195 class->lc_name, lock->lo_name, file, line); 1196 instance = find_instance(curthread->td_sleeplocks, lock); 1197 if (instance == NULL) 1198 panic("downgrade of unlocked lock (%s) %s @ %s:%d", 1199 class->lc_name, lock->lo_name, file, line); 1200 if ((instance->li_flags & LI_EXCLUSIVE) == 0) 1201 panic("downgrade of shared lock (%s) %s @ %s:%d", 1202 class->lc_name, lock->lo_name, file, line); 1203 if ((instance->li_flags & LI_RECURSEMASK) != 0) 1204 panic("downgrade of recursed lock (%s) %s r=%d @ %s:%d", 1205 class->lc_name, lock->lo_name, 1206 instance->li_flags & LI_RECURSEMASK, file, line); 1207 instance->li_flags &= ~LI_EXCLUSIVE; 1208 } 1209 1210 void 1211 witness_unlock(struct lock_object *lock, int flags, const char *file, int line) 1212 { 1213 struct lock_list_entry **lock_list, *lle; 1214 struct lock_instance *instance; 1215 struct lock_class *class; 1216 struct thread *td; 1217 register_t s; 1218 int i, j; 1219 1220 if (witness_cold || witness_watch == 0 || lock->lo_witness == NULL || 1221 panicstr != NULL) 1222 return; 1223 td = curthread; 1224 class = lock->lo_class; 1225 file = fixup_filename(file); 1226 1227 /* Find lock instance associated with this lock. */ 1228 if (class->lc_flags & LC_SLEEPLOCK) 1229 lock_list = &td->td_sleeplocks; 1230 else 1231 lock_list = PCPU_PTR(spinlocks); 1232 for (; *lock_list != NULL; lock_list = &(*lock_list)->ll_next) 1233 for (i = 0; i < (*lock_list)->ll_count; i++) { 1234 instance = &(*lock_list)->ll_children[i]; 1235 if (instance->li_lock == lock) 1236 goto found; 1237 } 1238 panic("lock (%s) %s not locked @ %s:%d", class->lc_name, lock->lo_name, 1239 file, line); 1240 found: 1241 1242 /* First, check for shared/exclusive mismatches. */ 1243 if ((instance->li_flags & LI_EXCLUSIVE) != 0 && 1244 (flags & LOP_EXCLUSIVE) == 0) { 1245 printf("shared unlock of (%s) %s @ %s:%d\n", class->lc_name, 1246 lock->lo_name, file, line); 1247 printf("while exclusively locked from %s:%d\n", 1248 instance->li_file, instance->li_line); 1249 panic("excl->ushare"); 1250 } 1251 if ((instance->li_flags & LI_EXCLUSIVE) == 0 && 1252 (flags & LOP_EXCLUSIVE) != 0) { 1253 printf("exclusive unlock of (%s) %s @ %s:%d\n", class->lc_name, 1254 lock->lo_name, file, line); 1255 printf("while share locked from %s:%d\n", instance->li_file, 1256 instance->li_line); 1257 panic("share->uexcl"); 1258 } 1259 1260 /* If we are recursed, unrecurse. */ 1261 if ((instance->li_flags & LI_RECURSEMASK) > 0) { 1262 CTR4(KTR_WITNESS, "%s: pid %d unrecursed on %s r=%d", __func__, 1263 td->td_proc->p_pid, instance->li_lock->lo_name, 1264 instance->li_flags); 1265 instance->li_flags--; 1266 return; 1267 } 1268 1269 /* Otherwise, remove this item from the list. */ 1270 s = intr_disable(); 1271 CTR4(KTR_WITNESS, "%s: pid %d removed %s from lle[%d]", __func__, 1272 td->td_proc->p_pid, instance->li_lock->lo_name, 1273 (*lock_list)->ll_count - 1); 1274 for (j = i; j < (*lock_list)->ll_count - 1; j++) 1275 (*lock_list)->ll_children[j] = 1276 (*lock_list)->ll_children[j + 1]; 1277 (*lock_list)->ll_count--; 1278 intr_restore(s); 1279 1280 /* If this lock list entry is now empty, free it. */ 1281 if ((*lock_list)->ll_count == 0) { 1282 lle = *lock_list; 1283 *lock_list = lle->ll_next; 1284 CTR3(KTR_WITNESS, "%s: pid %d removed lle %p", __func__, 1285 td->td_proc->p_pid, lle); 1286 witness_lock_list_free(lle); 1287 } 1288 } 1289 1290 /* 1291 * Warn if any locks other than 'lock' are held. Flags can be passed in to 1292 * exempt Giant and sleepable locks from the checks as well. If any 1293 * non-exempt locks are held, then a supplied message is printed to the 1294 * console along with a list of the offending locks. If indicated in the 1295 * flags then a failure results in a panic as well. 1296 */ 1297 int 1298 witness_warn(int flags, struct lock_object *lock, const char *fmt, ...) 1299 { 1300 struct lock_list_entry *lle; 1301 struct lock_instance *lock1; 1302 struct thread *td; 1303 va_list ap; 1304 int i, n; 1305 1306 if (witness_cold || witness_watch == 0 || panicstr != NULL) 1307 return (0); 1308 n = 0; 1309 td = curthread; 1310 for (lle = td->td_sleeplocks; lle != NULL; lle = lle->ll_next) 1311 for (i = lle->ll_count - 1; i >= 0; i--) { 1312 lock1 = &lle->ll_children[i]; 1313 if (lock1->li_lock == lock) 1314 continue; 1315 if (flags & WARN_GIANTOK && 1316 lock1->li_lock == &Giant.mtx_object) 1317 continue; 1318 if (flags & WARN_SLEEPOK && 1319 (lock1->li_lock->lo_flags & LO_SLEEPABLE) != 0) 1320 continue; 1321 if (n == 0) { 1322 va_start(ap, fmt); 1323 vprintf(fmt, ap); 1324 va_end(ap); 1325 printf(" with the following"); 1326 if (flags & WARN_SLEEPOK) 1327 printf(" non-sleepable"); 1328 printf(" locks held:\n"); 1329 } 1330 n++; 1331 witness_list_lock(lock1); 1332 } 1333 if (PCPU_GET(spinlocks) != NULL) { 1334 /* 1335 * Since we already hold a spinlock preemption is 1336 * already blocked. 1337 */ 1338 if (n == 0) { 1339 va_start(ap, fmt); 1340 vprintf(fmt, ap); 1341 va_end(ap); 1342 printf(" with the following"); 1343 if (flags & WARN_SLEEPOK) 1344 printf(" non-sleepable"); 1345 printf(" locks held:\n"); 1346 } 1347 n += witness_list_locks(PCPU_PTR(spinlocks)); 1348 } 1349 if (flags & WARN_PANIC && n) 1350 panic("witness_warn"); 1351 #ifdef KDB 1352 else if (witness_kdb && n) 1353 kdb_enter(__func__); 1354 else if (witness_trace && n) 1355 kdb_backtrace(); 1356 #endif 1357 return (n); 1358 } 1359 1360 const char * 1361 witness_file(struct lock_object *lock) 1362 { 1363 struct witness *w; 1364 1365 if (witness_cold || witness_watch == 0 || lock->lo_witness == NULL) 1366 return ("?"); 1367 w = lock->lo_witness; 1368 return (w->w_file); 1369 } 1370 1371 int 1372 witness_line(struct lock_object *lock) 1373 { 1374 struct witness *w; 1375 1376 if (witness_cold || witness_watch == 0 || lock->lo_witness == NULL) 1377 return (0); 1378 w = lock->lo_witness; 1379 return (w->w_line); 1380 } 1381 1382 static struct witness * 1383 enroll(const char *description, struct lock_class *lock_class) 1384 { 1385 struct witness *w; 1386 1387 if (witness_watch == 0 || panicstr != NULL) 1388 return (NULL); 1389 if ((lock_class->lc_flags & LC_SPINLOCK) && witness_skipspin) 1390 return (NULL); 1391 mtx_lock_spin(&w_mtx); 1392 STAILQ_FOREACH(w, &w_all, w_list) { 1393 if (w->w_name == description || (w->w_refcount > 0 && 1394 strcmp(description, w->w_name) == 0)) { 1395 w->w_refcount++; 1396 mtx_unlock_spin(&w_mtx); 1397 if (lock_class != w->w_class) 1398 panic( 1399 "lock (%s) %s does not match earlier (%s) lock", 1400 description, lock_class->lc_name, 1401 w->w_class->lc_name); 1402 return (w); 1403 } 1404 } 1405 /* 1406 * This isn't quite right, as witness_cold is still 0 while we 1407 * enroll all the locks initialized before witness_initialize(). 1408 */ 1409 if ((lock_class->lc_flags & LC_SPINLOCK) && !witness_cold) { 1410 mtx_unlock_spin(&w_mtx); 1411 panic("spin lock %s not in order list", description); 1412 } 1413 if ((w = witness_get()) == NULL) 1414 return (NULL); 1415 w->w_name = description; 1416 w->w_class = lock_class; 1417 w->w_refcount = 1; 1418 STAILQ_INSERT_HEAD(&w_all, w, w_list); 1419 if (lock_class->lc_flags & LC_SPINLOCK) { 1420 STAILQ_INSERT_HEAD(&w_spin, w, w_typelist); 1421 w_spin_cnt++; 1422 } else if (lock_class->lc_flags & LC_SLEEPLOCK) { 1423 STAILQ_INSERT_HEAD(&w_sleep, w, w_typelist); 1424 w_sleep_cnt++; 1425 } else { 1426 mtx_unlock_spin(&w_mtx); 1427 panic("lock class %s is not sleep or spin", 1428 lock_class->lc_name); 1429 } 1430 mtx_unlock_spin(&w_mtx); 1431 return (w); 1432 } 1433 1434 /* Don't let the door bang you on the way out... */ 1435 static int 1436 depart(struct witness *w) 1437 { 1438 struct witness_child_list_entry *wcl, *nwcl; 1439 struct witness_list *list; 1440 struct witness *parent; 1441 1442 MPASS(w->w_refcount == 0); 1443 if (w->w_class->lc_flags & LC_SLEEPLOCK) { 1444 list = &w_sleep; 1445 w_sleep_cnt--; 1446 } else { 1447 list = &w_spin; 1448 w_spin_cnt--; 1449 } 1450 /* 1451 * First, we run through the entire tree looking for any 1452 * witnesses that the outgoing witness is a child of. For 1453 * each parent that we find, we reparent all the direct 1454 * children of the outgoing witness to its parent. 1455 */ 1456 STAILQ_FOREACH(parent, list, w_typelist) { 1457 if (!isitmychild(parent, w)) 1458 continue; 1459 removechild(parent, w); 1460 } 1461 1462 /* 1463 * Now we go through and free up the child list of the 1464 * outgoing witness. 1465 */ 1466 for (wcl = w->w_children; wcl != NULL; wcl = nwcl) { 1467 nwcl = wcl->wcl_next; 1468 w_child_cnt--; 1469 witness_child_free(wcl); 1470 } 1471 1472 /* 1473 * Detach from various lists and free. 1474 */ 1475 STAILQ_REMOVE(list, w, witness, w_typelist); 1476 STAILQ_REMOVE(&w_all, w, witness, w_list); 1477 witness_free(w); 1478 1479 return (1); 1480 } 1481 1482 /* 1483 * Add "child" as a direct child of "parent". Returns false if 1484 * we fail due to out of memory. 1485 */ 1486 static int 1487 insertchild(struct witness *parent, struct witness *child) 1488 { 1489 struct witness_child_list_entry **wcl; 1490 1491 MPASS(child != NULL && parent != NULL); 1492 1493 /* 1494 * Insert "child" after "parent" 1495 */ 1496 wcl = &parent->w_children; 1497 while (*wcl != NULL && (*wcl)->wcl_count == WITNESS_NCHILDREN) 1498 wcl = &(*wcl)->wcl_next; 1499 if (*wcl == NULL) { 1500 *wcl = witness_child_get(); 1501 if (*wcl == NULL) 1502 return (0); 1503 w_child_cnt++; 1504 } 1505 (*wcl)->wcl_children[(*wcl)->wcl_count++] = child; 1506 1507 return (1); 1508 } 1509 1510 1511 static int 1512 itismychild(struct witness *parent, struct witness *child) 1513 { 1514 struct witness_list *list; 1515 1516 MPASS(child != NULL && parent != NULL); 1517 if ((parent->w_class->lc_flags & (LC_SLEEPLOCK | LC_SPINLOCK)) != 1518 (child->w_class->lc_flags & (LC_SLEEPLOCK | LC_SPINLOCK))) 1519 panic( 1520 "%s: parent (%s) and child (%s) are not the same lock type", 1521 __func__, parent->w_class->lc_name, 1522 child->w_class->lc_name); 1523 1524 if (!insertchild(parent, child)) 1525 return (0); 1526 1527 if (parent->w_class->lc_flags & LC_SLEEPLOCK) 1528 list = &w_sleep; 1529 else 1530 list = &w_spin; 1531 return (1); 1532 } 1533 1534 static void 1535 removechild(struct witness *parent, struct witness *child) 1536 { 1537 struct witness_child_list_entry **wcl, *wcl1; 1538 int i; 1539 1540 for (wcl = &parent->w_children; *wcl != NULL; wcl = &(*wcl)->wcl_next) 1541 for (i = 0; i < (*wcl)->wcl_count; i++) 1542 if ((*wcl)->wcl_children[i] == child) 1543 goto found; 1544 return; 1545 found: 1546 (*wcl)->wcl_count--; 1547 if ((*wcl)->wcl_count > i) 1548 (*wcl)->wcl_children[i] = 1549 (*wcl)->wcl_children[(*wcl)->wcl_count]; 1550 MPASS((*wcl)->wcl_children[i] != NULL); 1551 if ((*wcl)->wcl_count != 0) 1552 return; 1553 wcl1 = *wcl; 1554 *wcl = wcl1->wcl_next; 1555 w_child_cnt--; 1556 witness_child_free(wcl1); 1557 } 1558 1559 static int 1560 isitmychild(struct witness *parent, struct witness *child) 1561 { 1562 struct witness_child_list_entry *wcl; 1563 int i; 1564 1565 for (wcl = parent->w_children; wcl != NULL; wcl = wcl->wcl_next) { 1566 for (i = 0; i < wcl->wcl_count; i++) { 1567 if (wcl->wcl_children[i] == child) 1568 return (1); 1569 } 1570 } 1571 return (0); 1572 } 1573 1574 static int 1575 isitmydescendant(struct witness *parent, struct witness *child) 1576 { 1577 struct witness_child_list_entry *wcl; 1578 int i, j; 1579 1580 if (isitmychild(parent, child)) 1581 return (1); 1582 j = 0; 1583 for (wcl = parent->w_children; wcl != NULL; wcl = wcl->wcl_next) { 1584 MPASS(j < 1000); 1585 for (i = 0; i < wcl->wcl_count; i++) { 1586 if (isitmydescendant(wcl->wcl_children[i], child)) 1587 return (1); 1588 } 1589 j++; 1590 } 1591 return (0); 1592 } 1593 1594 #ifdef BLESSING 1595 static int 1596 blessed(struct witness *w1, struct witness *w2) 1597 { 1598 int i; 1599 struct witness_blessed *b; 1600 1601 for (i = 0; i < blessed_count; i++) { 1602 b = &blessed_list[i]; 1603 if (strcmp(w1->w_name, b->b_lock1) == 0) { 1604 if (strcmp(w2->w_name, b->b_lock2) == 0) 1605 return (1); 1606 continue; 1607 } 1608 if (strcmp(w1->w_name, b->b_lock2) == 0) 1609 if (strcmp(w2->w_name, b->b_lock1) == 0) 1610 return (1); 1611 } 1612 return (0); 1613 } 1614 #endif 1615 1616 static struct witness * 1617 witness_get(void) 1618 { 1619 struct witness *w; 1620 1621 if (witness_watch == 0) { 1622 mtx_unlock_spin(&w_mtx); 1623 return (NULL); 1624 } 1625 if (STAILQ_EMPTY(&w_free)) { 1626 witness_watch = 0; 1627 mtx_unlock_spin(&w_mtx); 1628 printf("%s: witness exhausted\n", __func__); 1629 return (NULL); 1630 } 1631 w = STAILQ_FIRST(&w_free); 1632 STAILQ_REMOVE_HEAD(&w_free, w_list); 1633 w_free_cnt--; 1634 bzero(w, sizeof(*w)); 1635 return (w); 1636 } 1637 1638 static void 1639 witness_free(struct witness *w) 1640 { 1641 1642 STAILQ_INSERT_HEAD(&w_free, w, w_list); 1643 w_free_cnt++; 1644 } 1645 1646 static struct witness_child_list_entry * 1647 witness_child_get(void) 1648 { 1649 struct witness_child_list_entry *wcl; 1650 1651 if (witness_watch == 0) { 1652 mtx_unlock_spin(&w_mtx); 1653 return (NULL); 1654 } 1655 wcl = w_child_free; 1656 if (wcl == NULL) { 1657 witness_watch = 0; 1658 mtx_unlock_spin(&w_mtx); 1659 printf("%s: witness exhausted\n", __func__); 1660 return (NULL); 1661 } 1662 w_child_free = wcl->wcl_next; 1663 w_child_free_cnt--; 1664 bzero(wcl, sizeof(*wcl)); 1665 return (wcl); 1666 } 1667 1668 static void 1669 witness_child_free(struct witness_child_list_entry *wcl) 1670 { 1671 1672 wcl->wcl_next = w_child_free; 1673 w_child_free = wcl; 1674 w_child_free_cnt++; 1675 } 1676 1677 static struct lock_list_entry * 1678 witness_lock_list_get(void) 1679 { 1680 struct lock_list_entry *lle; 1681 1682 if (witness_watch == 0) 1683 return (NULL); 1684 mtx_lock_spin(&w_mtx); 1685 lle = w_lock_list_free; 1686 if (lle == NULL) { 1687 witness_watch = 0; 1688 mtx_unlock_spin(&w_mtx); 1689 printf("%s: witness exhausted\n", __func__); 1690 return (NULL); 1691 } 1692 w_lock_list_free = lle->ll_next; 1693 mtx_unlock_spin(&w_mtx); 1694 bzero(lle, sizeof(*lle)); 1695 return (lle); 1696 } 1697 1698 static void 1699 witness_lock_list_free(struct lock_list_entry *lle) 1700 { 1701 1702 mtx_lock_spin(&w_mtx); 1703 lle->ll_next = w_lock_list_free; 1704 w_lock_list_free = lle; 1705 mtx_unlock_spin(&w_mtx); 1706 } 1707 1708 static struct lock_instance * 1709 find_instance(struct lock_list_entry *lock_list, struct lock_object *lock) 1710 { 1711 struct lock_list_entry *lle; 1712 struct lock_instance *instance; 1713 int i; 1714 1715 for (lle = lock_list; lle != NULL; lle = lle->ll_next) 1716 for (i = lle->ll_count - 1; i >= 0; i--) { 1717 instance = &lle->ll_children[i]; 1718 if (instance->li_lock == lock) 1719 return (instance); 1720 } 1721 return (NULL); 1722 } 1723 1724 static void 1725 witness_list_lock(struct lock_instance *instance) 1726 { 1727 struct lock_object *lock; 1728 1729 lock = instance->li_lock; 1730 printf("%s %s %s", (instance->li_flags & LI_EXCLUSIVE) != 0 ? 1731 "exclusive" : "shared", lock->lo_class->lc_name, lock->lo_name); 1732 if (lock->lo_type != lock->lo_name) 1733 printf(" (%s)", lock->lo_type); 1734 printf(" r = %d (%p) locked @ %s:%d\n", 1735 instance->li_flags & LI_RECURSEMASK, lock, instance->li_file, 1736 instance->li_line); 1737 } 1738 1739 #ifdef DDB 1740 static int 1741 witness_thread_has_locks(struct thread *td) 1742 { 1743 1744 return (td->td_sleeplocks != NULL); 1745 } 1746 1747 static int 1748 witness_proc_has_locks(struct proc *p) 1749 { 1750 struct thread *td; 1751 1752 FOREACH_THREAD_IN_PROC(p, td) { 1753 if (witness_thread_has_locks(td)) 1754 return (1); 1755 } 1756 return (0); 1757 } 1758 #endif 1759 1760 int 1761 witness_list_locks(struct lock_list_entry **lock_list) 1762 { 1763 struct lock_list_entry *lle; 1764 int i, nheld; 1765 1766 nheld = 0; 1767 for (lle = *lock_list; lle != NULL; lle = lle->ll_next) 1768 for (i = lle->ll_count - 1; i >= 0; i--) { 1769 witness_list_lock(&lle->ll_children[i]); 1770 nheld++; 1771 } 1772 return (nheld); 1773 } 1774 1775 /* 1776 * This is a bit risky at best. We call this function when we have timed 1777 * out acquiring a spin lock, and we assume that the other CPU is stuck 1778 * with this lock held. So, we go groveling around in the other CPU's 1779 * per-cpu data to try to find the lock instance for this spin lock to 1780 * see when it was last acquired. 1781 */ 1782 void 1783 witness_display_spinlock(struct lock_object *lock, struct thread *owner) 1784 { 1785 struct lock_instance *instance; 1786 struct pcpu *pc; 1787 1788 if (owner->td_critnest == 0 || owner->td_oncpu == NOCPU) 1789 return; 1790 pc = pcpu_find(owner->td_oncpu); 1791 instance = find_instance(pc->pc_spinlocks, lock); 1792 if (instance != NULL) 1793 witness_list_lock(instance); 1794 } 1795 1796 void 1797 witness_save(struct lock_object *lock, const char **filep, int *linep) 1798 { 1799 struct lock_instance *instance; 1800 1801 KASSERT(!witness_cold, ("%s: witness_cold", __func__)); 1802 if (lock->lo_witness == NULL || witness_watch == 0 || panicstr != NULL) 1803 return; 1804 if ((lock->lo_class->lc_flags & LC_SLEEPLOCK) == 0) 1805 panic("%s: lock (%s) %s is not a sleep lock", __func__, 1806 lock->lo_class->lc_name, lock->lo_name); 1807 instance = find_instance(curthread->td_sleeplocks, lock); 1808 if (instance == NULL) 1809 panic("%s: lock (%s) %s not locked", __func__, 1810 lock->lo_class->lc_name, lock->lo_name); 1811 *filep = instance->li_file; 1812 *linep = instance->li_line; 1813 } 1814 1815 void 1816 witness_restore(struct lock_object *lock, const char *file, int line) 1817 { 1818 struct lock_instance *instance; 1819 1820 KASSERT(!witness_cold, ("%s: witness_cold", __func__)); 1821 if (lock->lo_witness == NULL || witness_watch == 0 || panicstr != NULL) 1822 return; 1823 if ((lock->lo_class->lc_flags & LC_SLEEPLOCK) == 0) 1824 panic("%s: lock (%s) %s is not a sleep lock", __func__, 1825 lock->lo_class->lc_name, lock->lo_name); 1826 instance = find_instance(curthread->td_sleeplocks, lock); 1827 if (instance == NULL) 1828 panic("%s: lock (%s) %s not locked", __func__, 1829 lock->lo_class->lc_name, lock->lo_name); 1830 lock->lo_witness->w_file = file; 1831 lock->lo_witness->w_line = line; 1832 instance->li_file = file; 1833 instance->li_line = line; 1834 } 1835 1836 void 1837 witness_assert(struct lock_object *lock, int flags, const char *file, int line) 1838 { 1839 #ifdef INVARIANT_SUPPORT 1840 struct lock_instance *instance; 1841 1842 if (lock->lo_witness == NULL || witness_watch == 0 || panicstr != NULL) 1843 return; 1844 if ((lock->lo_class->lc_flags & LC_SLEEPLOCK) != 0) 1845 instance = find_instance(curthread->td_sleeplocks, lock); 1846 else if ((lock->lo_class->lc_flags & LC_SPINLOCK) != 0) 1847 instance = find_instance(PCPU_GET(spinlocks), lock); 1848 else { 1849 panic("Lock (%s) %s is not sleep or spin!", 1850 lock->lo_class->lc_name, lock->lo_name); 1851 } 1852 file = fixup_filename(file); 1853 switch (flags) { 1854 case LA_UNLOCKED: 1855 if (instance != NULL) 1856 panic("Lock (%s) %s locked @ %s:%d.", 1857 lock->lo_class->lc_name, lock->lo_name, file, line); 1858 break; 1859 case LA_LOCKED: 1860 case LA_LOCKED | LA_RECURSED: 1861 case LA_LOCKED | LA_NOTRECURSED: 1862 case LA_SLOCKED: 1863 case LA_SLOCKED | LA_RECURSED: 1864 case LA_SLOCKED | LA_NOTRECURSED: 1865 case LA_XLOCKED: 1866 case LA_XLOCKED | LA_RECURSED: 1867 case LA_XLOCKED | LA_NOTRECURSED: 1868 if (instance == NULL) { 1869 panic("Lock (%s) %s not locked @ %s:%d.", 1870 lock->lo_class->lc_name, lock->lo_name, file, line); 1871 break; 1872 } 1873 if ((flags & LA_XLOCKED) != 0 && 1874 (instance->li_flags & LI_EXCLUSIVE) == 0) 1875 panic("Lock (%s) %s not exclusively locked @ %s:%d.", 1876 lock->lo_class->lc_name, lock->lo_name, file, line); 1877 if ((flags & LA_SLOCKED) != 0 && 1878 (instance->li_flags & LI_EXCLUSIVE) != 0) 1879 panic("Lock (%s) %s exclusively locked @ %s:%d.", 1880 lock->lo_class->lc_name, lock->lo_name, file, line); 1881 if ((flags & LA_RECURSED) != 0 && 1882 (instance->li_flags & LI_RECURSEMASK) == 0) 1883 panic("Lock (%s) %s not recursed @ %s:%d.", 1884 lock->lo_class->lc_name, lock->lo_name, file, line); 1885 if ((flags & LA_NOTRECURSED) != 0 && 1886 (instance->li_flags & LI_RECURSEMASK) != 0) 1887 panic("Lock (%s) %s recursed @ %s:%d.", 1888 lock->lo_class->lc_name, lock->lo_name, file, line); 1889 break; 1890 default: 1891 panic("Invalid lock assertion at %s:%d.", file, line); 1892 1893 } 1894 #endif /* INVARIANT_SUPPORT */ 1895 } 1896 1897 #ifdef DDB 1898 static void 1899 witness_list(struct thread *td) 1900 { 1901 1902 KASSERT(!witness_cold, ("%s: witness_cold", __func__)); 1903 KASSERT(kdb_active, ("%s: not in the debugger", __func__)); 1904 1905 if (witness_watch == 0) 1906 return; 1907 1908 witness_list_locks(&td->td_sleeplocks); 1909 1910 /* 1911 * We only handle spinlocks if td == curthread. This is somewhat broken 1912 * if td is currently executing on some other CPU and holds spin locks 1913 * as we won't display those locks. If we had a MI way of getting 1914 * the per-cpu data for a given cpu then we could use 1915 * td->td_oncpu to get the list of spinlocks for this thread 1916 * and "fix" this. 1917 * 1918 * That still wouldn't really fix this unless we locked sched_lock 1919 * or stopped the other CPU to make sure it wasn't changing the list 1920 * out from under us. It is probably best to just not try to handle 1921 * threads on other CPU's for now. 1922 */ 1923 if (td == curthread && PCPU_GET(spinlocks) != NULL) 1924 witness_list_locks(PCPU_PTR(spinlocks)); 1925 } 1926 1927 DB_SHOW_COMMAND(locks, db_witness_list) 1928 { 1929 struct thread *td; 1930 pid_t pid; 1931 struct proc *p; 1932 1933 if (have_addr) { 1934 pid = (addr % 16) + ((addr >> 4) % 16) * 10 + 1935 ((addr >> 8) % 16) * 100 + ((addr >> 12) % 16) * 1000 + 1936 ((addr >> 16) % 16) * 10000; 1937 /* sx_slock(&allproc_lock); */ 1938 FOREACH_PROC_IN_SYSTEM(p) { 1939 if (p->p_pid == pid) 1940 break; 1941 } 1942 /* sx_sunlock(&allproc_lock); */ 1943 if (p == NULL) { 1944 db_printf("pid %d not found\n", pid); 1945 return; 1946 } 1947 FOREACH_THREAD_IN_PROC(p, td) { 1948 witness_list(td); 1949 } 1950 } else { 1951 td = curthread; 1952 witness_list(td); 1953 } 1954 } 1955 1956 DB_SHOW_COMMAND(alllocks, db_witness_list_all) 1957 { 1958 struct thread *td; 1959 struct proc *p; 1960 1961 /* 1962 * It would be nice to list only threads and processes that actually 1963 * held sleep locks, but that information is currently not exported 1964 * by WITNESS. 1965 */ 1966 FOREACH_PROC_IN_SYSTEM(p) { 1967 if (!witness_proc_has_locks(p)) 1968 continue; 1969 FOREACH_THREAD_IN_PROC(p, td) { 1970 if (!witness_thread_has_locks(td)) 1971 continue; 1972 printf("Process %d (%s) thread %p (%d)\n", p->p_pid, 1973 p->p_comm, td, td->td_tid); 1974 witness_list(td); 1975 } 1976 } 1977 } 1978 1979 DB_SHOW_COMMAND(witness, db_witness_display) 1980 { 1981 1982 witness_display(db_printf); 1983 } 1984 #endif 1985