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FreeBSD/Linux Kernel Cross Reference
sys/kern/subr_witness.c
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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: releng/6.0/sys/kern/subr_witness.c 151667 2005-10-25 20:17:11Z jhb $"); 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 int rebalancetree(struct witness_list *list); 169 static void removechild(struct witness *parent, struct witness *child); 170 static int reparentchildren(struct witness *newparent, 171 struct witness *oldparent); 172 static int sysctl_debug_witness_watch(SYSCTL_HANDLER_ARGS); 173 static void witness_displaydescendants(void(*)(const char *fmt, ...), 174 struct witness *, int indent); 175 static const char *fixup_filename(const char *file); 176 static void witness_leveldescendents(struct witness *parent, int level); 177 static void witness_levelall(void); 178 static struct witness *witness_get(void); 179 static void witness_free(struct witness *m); 180 static struct witness_child_list_entry *witness_child_get(void); 181 static void witness_child_free(struct witness_child_list_entry *wcl); 182 static struct lock_list_entry *witness_lock_list_get(void); 183 static void witness_lock_list_free(struct lock_list_entry *lle); 184 static struct lock_instance *find_instance(struct lock_list_entry *lock_list, 185 struct lock_object *lock); 186 static void witness_list_lock(struct lock_instance *instance); 187 #ifdef DDB 188 static void witness_list(struct thread *td); 189 static void witness_display_list(void(*prnt)(const char *fmt, ...), 190 struct witness_list *list); 191 static void witness_display(void(*)(const char *fmt, ...)); 192 #endif 193 194 SYSCTL_NODE(_debug, OID_AUTO, witness, CTLFLAG_RW, 0, "Witness Locking"); 195 196 /* 197 * If set to 0, witness is disabled. If set to 1, witness performs full lock 198 * order checking for all locks. If set to 2 or higher, then witness skips 199 * the full lock order check if the lock being acquired is at a higher level 200 * (i.e. farther down in the tree) than the current lock. This last mode is 201 * somewhat experimental and not considered fully safe. At runtime, this 202 * value may be set to 0 to turn off witness. witness is not allowed be 203 * turned on once it is turned off, however. 204 */ 205 static int witness_watch = 1; 206 TUNABLE_INT("debug.witness.watch", &witness_watch); 207 SYSCTL_PROC(_debug_witness, OID_AUTO, watch, CTLFLAG_RW | CTLTYPE_INT, NULL, 0, 208 sysctl_debug_witness_watch, "I", "witness is watching lock operations"); 209 210 #ifdef KDB 211 /* 212 * When KDB is enabled and witness_kdb is set to 1, it will cause the system 213 * to drop into kdebug() when: 214 * - a lock heirarchy violation occurs 215 * - locks are held when going to sleep. 216 */ 217 #ifdef WITNESS_KDB 218 int witness_kdb = 1; 219 #else 220 int witness_kdb = 0; 221 #endif 222 TUNABLE_INT("debug.witness.kdb", &witness_kdb); 223 SYSCTL_INT(_debug_witness, OID_AUTO, kdb, CTLFLAG_RW, &witness_kdb, 0, ""); 224 225 /* 226 * When KDB is enabled and witness_trace is set to 1, it will cause the system 227 * to print a stack trace: 228 * - a lock heirarchy violation occurs 229 * - locks are held when going to sleep. 230 */ 231 int witness_trace = 1; 232 TUNABLE_INT("debug.witness.trace", &witness_trace); 233 SYSCTL_INT(_debug_witness, OID_AUTO, trace, CTLFLAG_RW, &witness_trace, 0, ""); 234 #endif /* KDB */ 235 236 #ifdef WITNESS_SKIPSPIN 237 int witness_skipspin = 1; 238 #else 239 int witness_skipspin = 0; 240 #endif 241 TUNABLE_INT("debug.witness.skipspin", &witness_skipspin); 242 SYSCTL_INT(_debug_witness, OID_AUTO, skipspin, CTLFLAG_RDTUN, 243 &witness_skipspin, 0, ""); 244 245 static struct mtx w_mtx; 246 static struct witness_list w_free = STAILQ_HEAD_INITIALIZER(w_free); 247 static struct witness_list w_all = STAILQ_HEAD_INITIALIZER(w_all); 248 static struct witness_list w_spin = STAILQ_HEAD_INITIALIZER(w_spin); 249 static struct witness_list w_sleep = STAILQ_HEAD_INITIALIZER(w_sleep); 250 static struct witness_child_list_entry *w_child_free = NULL; 251 static struct lock_list_entry *w_lock_list_free = NULL; 252 253 static struct witness w_data[WITNESS_COUNT]; 254 static struct witness_child_list_entry w_childdata[WITNESS_CHILDCOUNT]; 255 static struct lock_list_entry w_locklistdata[LOCK_CHILDCOUNT]; 256 257 static struct witness_order_list_entry order_lists[] = { 258 /* 259 * sx locks 260 */ 261 { "proctree", &lock_class_sx }, 262 { "allproc", &lock_class_sx }, 263 { NULL, NULL }, 264 /* 265 * Various mutexes 266 */ 267 { "Giant", &lock_class_mtx_sleep }, 268 { "filedesc structure", &lock_class_mtx_sleep }, 269 { "pipe mutex", &lock_class_mtx_sleep }, 270 { "sigio lock", &lock_class_mtx_sleep }, 271 { "process group", &lock_class_mtx_sleep }, 272 { "process lock", &lock_class_mtx_sleep }, 273 { "session", &lock_class_mtx_sleep }, 274 { "uidinfo hash", &lock_class_mtx_sleep }, 275 { "uidinfo struct", &lock_class_mtx_sleep }, 276 { "allprison", &lock_class_mtx_sleep }, 277 { NULL, NULL }, 278 /* 279 * Sockets 280 */ 281 { "filedesc structure", &lock_class_mtx_sleep }, 282 { "accept", &lock_class_mtx_sleep }, 283 { "so_snd", &lock_class_mtx_sleep }, 284 { "so_rcv", &lock_class_mtx_sleep }, 285 { "sellck", &lock_class_mtx_sleep }, 286 { NULL, NULL }, 287 /* 288 * Routing 289 */ 290 { "so_rcv", &lock_class_mtx_sleep }, 291 { "radix node head", &lock_class_mtx_sleep }, 292 { "rtentry", &lock_class_mtx_sleep }, 293 { "ifaddr", &lock_class_mtx_sleep }, 294 { NULL, NULL }, 295 /* 296 * Multicast - protocol locks before interface locks. 297 */ 298 { "in_multi_mtx", &lock_class_mtx_sleep }, 299 { "igmp_mtx", &lock_class_mtx_sleep }, 300 { "if_addr_mtx", &lock_class_mtx_sleep }, 301 { NULL, NULL }, 302 /* 303 * UNIX Domain Sockets 304 */ 305 { "unp", &lock_class_mtx_sleep }, 306 { "so_snd", &lock_class_mtx_sleep }, 307 { NULL, NULL }, 308 /* 309 * UDP/IP 310 */ 311 { "udp", &lock_class_mtx_sleep }, 312 { "udpinp", &lock_class_mtx_sleep }, 313 { "so_snd", &lock_class_mtx_sleep }, 314 { NULL, NULL }, 315 /* 316 * TCP/IP 317 */ 318 { "tcp", &lock_class_mtx_sleep }, 319 { "tcpinp", &lock_class_mtx_sleep }, 320 { "so_snd", &lock_class_mtx_sleep }, 321 { NULL, NULL }, 322 /* 323 * SLIP 324 */ 325 { "slip_mtx", &lock_class_mtx_sleep }, 326 { "slip sc_mtx", &lock_class_mtx_sleep }, 327 { NULL, NULL }, 328 /* 329 * netatalk 330 */ 331 { "ddp_list_mtx", &lock_class_mtx_sleep }, 332 { "ddp_mtx", &lock_class_mtx_sleep }, 333 { NULL, NULL }, 334 /* 335 * BPF 336 */ 337 { "bpf global lock", &lock_class_mtx_sleep }, 338 { "bpf interface lock", &lock_class_mtx_sleep }, 339 { "bpf cdev lock", &lock_class_mtx_sleep }, 340 { NULL, NULL }, 341 /* 342 * NFS server 343 */ 344 { "nfsd_mtx", &lock_class_mtx_sleep }, 345 { "so_snd", &lock_class_mtx_sleep }, 346 { NULL, NULL }, 347 /* 348 * CDEV 349 */ 350 { "system map", &lock_class_mtx_sleep }, 351 { "vm page queue mutex", &lock_class_mtx_sleep }, 352 { "vnode interlock", &lock_class_mtx_sleep }, 353 { "cdev", &lock_class_mtx_sleep }, 354 { NULL, NULL }, 355 /* 356 * spin locks 357 */ 358 #ifdef SMP 359 { "ap boot", &lock_class_mtx_spin }, 360 #endif 361 { "rm.mutex_mtx", &lock_class_mtx_spin }, 362 { "sio", &lock_class_mtx_spin }, 363 #ifdef __i386__ 364 { "cy", &lock_class_mtx_spin }, 365 #endif 366 { "uart_hwmtx", &lock_class_mtx_spin }, 367 { "sabtty", &lock_class_mtx_spin }, 368 { "zstty", &lock_class_mtx_spin }, 369 { "ng_node", &lock_class_mtx_spin }, 370 { "ng_worklist", &lock_class_mtx_spin }, 371 { "taskqueue_fast", &lock_class_mtx_spin }, 372 { "intr table", &lock_class_mtx_spin }, 373 { "ithread table lock", &lock_class_mtx_spin }, 374 { "sleepq chain", &lock_class_mtx_spin }, 375 { "sched lock", &lock_class_mtx_spin }, 376 { "turnstile chain", &lock_class_mtx_spin }, 377 { "td_contested", &lock_class_mtx_spin }, 378 { "callout", &lock_class_mtx_spin }, 379 { "entropy harvest mutex", &lock_class_mtx_spin }, 380 /* 381 * leaf locks 382 */ 383 { "allpmaps", &lock_class_mtx_spin }, 384 { "vm page queue free mutex", &lock_class_mtx_spin }, 385 { "icu", &lock_class_mtx_spin }, 386 #ifdef SMP 387 { "smp rendezvous", &lock_class_mtx_spin }, 388 #if defined(__i386__) || defined(__amd64__) 389 { "tlb", &lock_class_mtx_spin }, 390 #endif 391 #ifdef __sparc64__ 392 { "ipi", &lock_class_mtx_spin }, 393 { "rtc_mtx", &lock_class_mtx_spin }, 394 #endif 395 #endif 396 { "clk", &lock_class_mtx_spin }, 397 { "mutex profiling lock", &lock_class_mtx_spin }, 398 { "kse zombie lock", &lock_class_mtx_spin }, 399 { "ALD Queue", &lock_class_mtx_spin }, 400 #ifdef __ia64__ 401 { "MCA spin lock", &lock_class_mtx_spin }, 402 #endif 403 #if defined(__i386__) || defined(__amd64__) 404 { "pcicfg", &lock_class_mtx_spin }, 405 { "NDIS thread lock", &lock_class_mtx_spin }, 406 #endif 407 { "tw_osl_io_lock", &lock_class_mtx_spin }, 408 { "tw_osl_q_lock", &lock_class_mtx_spin }, 409 { "tw_cl_io_lock", &lock_class_mtx_spin }, 410 { "tw_cl_intr_lock", &lock_class_mtx_spin }, 411 { "tw_cl_gen_lock", &lock_class_mtx_spin }, 412 { NULL, NULL }, 413 { NULL, NULL } 414 }; 415 416 #ifdef BLESSING 417 /* 418 * Pairs of locks which have been blessed 419 * Don't complain about order problems with blessed locks 420 */ 421 static struct witness_blessed blessed_list[] = { 422 }; 423 static int blessed_count = 424 sizeof(blessed_list) / sizeof(struct witness_blessed); 425 #endif 426 427 /* 428 * List of all locks in the system. 429 */ 430 TAILQ_HEAD(, lock_object) all_locks = TAILQ_HEAD_INITIALIZER(all_locks); 431 432 static struct mtx all_mtx = { 433 { &lock_class_mtx_sleep, /* mtx_object.lo_class */ 434 "All locks list", /* mtx_object.lo_name */ 435 "All locks list", /* mtx_object.lo_type */ 436 LO_INITIALIZED, /* mtx_object.lo_flags */ 437 { NULL, NULL }, /* mtx_object.lo_list */ 438 NULL }, /* mtx_object.lo_witness */ 439 MTX_UNOWNED, 0 /* mtx_lock, mtx_recurse */ 440 }; 441 442 /* 443 * This global is set to 0 once it becomes safe to use the witness code. 444 */ 445 static int witness_cold = 1; 446 447 /* 448 * This global is set to 1 once the static lock orders have been enrolled 449 * so that a warning can be issued for any spin locks enrolled later. 450 */ 451 static int witness_spin_warn = 0; 452 453 /* 454 * Global variables for book keeping. 455 */ 456 static int lock_cur_cnt; 457 static int lock_max_cnt; 458 459 /* 460 * The WITNESS-enabled diagnostic code. 461 */ 462 static void 463 witness_initialize(void *dummy __unused) 464 { 465 struct lock_object *lock; 466 struct witness_order_list_entry *order; 467 struct witness *w, *w1; 468 int i; 469 470 /* 471 * We have to release Giant before initializing its witness 472 * structure so that WITNESS doesn't get confused. 473 */ 474 mtx_unlock(&Giant); 475 mtx_assert(&Giant, MA_NOTOWNED); 476 477 CTR1(KTR_WITNESS, "%s: initializing witness", __func__); 478 TAILQ_INSERT_HEAD(&all_locks, &all_mtx.mtx_object, lo_list); 479 mtx_init(&w_mtx, "witness lock", NULL, MTX_SPIN | MTX_QUIET | 480 MTX_NOWITNESS); 481 for (i = 0; i < WITNESS_COUNT; i++) 482 witness_free(&w_data[i]); 483 for (i = 0; i < WITNESS_CHILDCOUNT; i++) 484 witness_child_free(&w_childdata[i]); 485 for (i = 0; i < LOCK_CHILDCOUNT; i++) 486 witness_lock_list_free(&w_locklistdata[i]); 487 488 /* First add in all the specified order lists. */ 489 for (order = order_lists; order->w_name != NULL; order++) { 490 w = enroll(order->w_name, order->w_class); 491 if (w == NULL) 492 continue; 493 w->w_file = "order list"; 494 for (order++; order->w_name != NULL; order++) { 495 w1 = enroll(order->w_name, order->w_class); 496 if (w1 == NULL) 497 continue; 498 w1->w_file = "order list"; 499 if (!itismychild(w, w1)) 500 panic("Not enough memory for static orders!"); 501 w = w1; 502 } 503 } 504 witness_spin_warn = 1; 505 506 /* Iterate through all locks and add them to witness. */ 507 mtx_lock(&all_mtx); 508 TAILQ_FOREACH(lock, &all_locks, lo_list) { 509 if (lock->lo_flags & LO_WITNESS) 510 lock->lo_witness = enroll(lock->lo_type, 511 lock->lo_class); 512 else 513 lock->lo_witness = NULL; 514 } 515 mtx_unlock(&all_mtx); 516 517 /* Mark the witness code as being ready for use. */ 518 witness_cold = 0; 519 520 mtx_lock(&Giant); 521 } 522 SYSINIT(witness_init, SI_SUB_WITNESS, SI_ORDER_FIRST, witness_initialize, NULL) 523 524 static int 525 sysctl_debug_witness_watch(SYSCTL_HANDLER_ARGS) 526 { 527 int error, value; 528 529 value = witness_watch; 530 error = sysctl_handle_int(oidp, &value, 0, req); 531 if (error != 0 || req->newptr == NULL) 532 return (error); 533 error = suser(req->td); 534 if (error != 0) 535 return (error); 536 if (value == witness_watch) 537 return (0); 538 if (value != 0) 539 return (EINVAL); 540 witness_watch = 0; 541 return (0); 542 } 543 544 void 545 witness_init(struct lock_object *lock) 546 { 547 struct lock_class *class; 548 549 class = lock->lo_class; 550 if (lock->lo_flags & LO_INITIALIZED) 551 panic("%s: lock (%s) %s is already initialized", __func__, 552 class->lc_name, lock->lo_name); 553 if ((lock->lo_flags & LO_RECURSABLE) != 0 && 554 (class->lc_flags & LC_RECURSABLE) == 0) 555 panic("%s: lock (%s) %s can not be recursable", __func__, 556 class->lc_name, lock->lo_name); 557 if ((lock->lo_flags & LO_SLEEPABLE) != 0 && 558 (class->lc_flags & LC_SLEEPABLE) == 0) 559 panic("%s: lock (%s) %s can not be sleepable", __func__, 560 class->lc_name, lock->lo_name); 561 if ((lock->lo_flags & LO_UPGRADABLE) != 0 && 562 (class->lc_flags & LC_UPGRADABLE) == 0) 563 panic("%s: lock (%s) %s can not be upgradable", __func__, 564 class->lc_name, lock->lo_name); 565 566 mtx_lock(&all_mtx); 567 TAILQ_INSERT_TAIL(&all_locks, lock, lo_list); 568 lock->lo_flags |= LO_INITIALIZED; 569 lock_cur_cnt++; 570 if (lock_cur_cnt > lock_max_cnt) 571 lock_max_cnt = lock_cur_cnt; 572 mtx_unlock(&all_mtx); 573 if (!witness_cold && witness_watch != 0 && panicstr == NULL && 574 (lock->lo_flags & LO_WITNESS) != 0) 575 lock->lo_witness = enroll(lock->lo_type, class); 576 else 577 lock->lo_witness = NULL; 578 } 579 580 void 581 witness_destroy(struct lock_object *lock) 582 { 583 struct witness *w; 584 585 if (witness_cold) 586 panic("lock (%s) %s destroyed while witness_cold", 587 lock->lo_class->lc_name, lock->lo_name); 588 if ((lock->lo_flags & LO_INITIALIZED) == 0) 589 panic("%s: lock (%s) %s is not initialized", __func__, 590 lock->lo_class->lc_name, lock->lo_name); 591 592 /* XXX: need to verify that no one holds the lock */ 593 w = lock->lo_witness; 594 if (w != NULL) { 595 mtx_lock_spin(&w_mtx); 596 MPASS(w->w_refcount > 0); 597 w->w_refcount--; 598 599 /* 600 * Lock is already released if we have an allocation failure 601 * and depart() fails. 602 */ 603 if (w->w_refcount != 0 || depart(w)) 604 mtx_unlock_spin(&w_mtx); 605 } 606 607 mtx_lock(&all_mtx); 608 lock_cur_cnt--; 609 TAILQ_REMOVE(&all_locks, lock, lo_list); 610 lock->lo_flags &= ~LO_INITIALIZED; 611 mtx_unlock(&all_mtx); 612 } 613 614 #ifdef DDB 615 static void 616 witness_display_list(void(*prnt)(const char *fmt, ...), 617 struct witness_list *list) 618 { 619 struct witness *w; 620 621 STAILQ_FOREACH(w, list, w_typelist) { 622 if (w->w_file == NULL || w->w_level > 0) 623 continue; 624 /* 625 * This lock has no anscestors, display its descendants. 626 */ 627 witness_displaydescendants(prnt, w, 0); 628 } 629 } 630 631 static void 632 witness_display(void(*prnt)(const char *fmt, ...)) 633 { 634 struct witness *w; 635 636 KASSERT(!witness_cold, ("%s: witness_cold", __func__)); 637 witness_levelall(); 638 639 /* Clear all the displayed flags. */ 640 STAILQ_FOREACH(w, &w_all, w_list) { 641 w->w_displayed = 0; 642 } 643 644 /* 645 * First, handle sleep locks which have been acquired at least 646 * once. 647 */ 648 prnt("Sleep locks:\n"); 649 witness_display_list(prnt, &w_sleep); 650 651 /* 652 * Now do spin locks which have been acquired at least once. 653 */ 654 prnt("\nSpin locks:\n"); 655 witness_display_list(prnt, &w_spin); 656 657 /* 658 * Finally, any locks which have not been acquired yet. 659 */ 660 prnt("\nLocks which were never acquired:\n"); 661 STAILQ_FOREACH(w, &w_all, w_list) { 662 if (w->w_file != NULL || w->w_refcount == 0) 663 continue; 664 prnt("%s\n", w->w_name); 665 } 666 } 667 #endif /* DDB */ 668 669 /* Trim useless garbage from filenames. */ 670 static const char * 671 fixup_filename(const char *file) 672 { 673 674 if (file == NULL) 675 return (NULL); 676 while (strncmp(file, "../", 3) == 0) 677 file += 3; 678 return (file); 679 } 680 681 int 682 witness_defineorder(struct lock_object *lock1, struct lock_object *lock2) 683 { 684 685 if (witness_watch == 0 || panicstr != NULL) 686 return (0); 687 688 /* Require locks that witness knows about. */ 689 if (lock1 == NULL || lock1->lo_witness == NULL || lock2 == NULL || 690 lock2->lo_witness == NULL) 691 return (EINVAL); 692 693 MPASS(!mtx_owned(&w_mtx)); 694 mtx_lock_spin(&w_mtx); 695 696 /* 697 * If we already have either an explicit or implied lock order that 698 * is the other way around, then return an error. 699 */ 700 if (isitmydescendant(lock2->lo_witness, lock1->lo_witness)) { 701 mtx_unlock_spin(&w_mtx); 702 return (EDOOFUS); 703 } 704 705 /* Try to add the new order. */ 706 CTR3(KTR_WITNESS, "%s: adding %s as a child of %s", __func__, 707 lock2->lo_type, lock1->lo_type); 708 if (!itismychild(lock1->lo_witness, lock2->lo_witness)) 709 return (ENOMEM); 710 mtx_unlock_spin(&w_mtx); 711 return (0); 712 } 713 714 void 715 witness_checkorder(struct lock_object *lock, int flags, const char *file, 716 int line) 717 { 718 struct lock_list_entry **lock_list, *lle; 719 struct lock_instance *lock1, *lock2; 720 struct lock_class *class; 721 struct witness *w, *w1; 722 struct thread *td; 723 int i, j; 724 725 if (witness_cold || witness_watch == 0 || lock->lo_witness == NULL || 726 panicstr != NULL) 727 return; 728 729 /* 730 * Try locks do not block if they fail to acquire the lock, thus 731 * there is no danger of deadlocks or of switching while holding a 732 * spin lock if we acquire a lock via a try operation. This 733 * function shouldn't even be called for try locks, so panic if 734 * that happens. 735 */ 736 if (flags & LOP_TRYLOCK) 737 panic("%s should not be called for try lock operations", 738 __func__); 739 740 w = lock->lo_witness; 741 class = lock->lo_class; 742 td = curthread; 743 file = fixup_filename(file); 744 745 if (class->lc_flags & LC_SLEEPLOCK) { 746 /* 747 * Since spin locks include a critical section, this check 748 * implicitly enforces a lock order of all sleep locks before 749 * all spin locks. 750 */ 751 if (td->td_critnest != 0 && !kdb_active) 752 panic("blockable sleep lock (%s) %s @ %s:%d", 753 class->lc_name, lock->lo_name, file, line); 754 755 /* 756 * If this is the first lock acquired then just return as 757 * no order checking is needed. 758 */ 759 if (td->td_sleeplocks == NULL) 760 return; 761 lock_list = &td->td_sleeplocks; 762 } else { 763 /* 764 * If this is the first lock, just return as no order 765 * checking is needed. We check this in both if clauses 766 * here as unifying the check would require us to use a 767 * critical section to ensure we don't migrate while doing 768 * the check. Note that if this is not the first lock, we 769 * are already in a critical section and are safe for the 770 * rest of the check. 771 */ 772 if (PCPU_GET(spinlocks) == NULL) 773 return; 774 lock_list = PCPU_PTR(spinlocks); 775 } 776 777 /* 778 * Check to see if we are recursing on a lock we already own. If 779 * so, make sure that we don't mismatch exclusive and shared lock 780 * acquires. 781 */ 782 lock1 = find_instance(*lock_list, lock); 783 if (lock1 != NULL) { 784 if ((lock1->li_flags & LI_EXCLUSIVE) != 0 && 785 (flags & LOP_EXCLUSIVE) == 0) { 786 printf("shared lock of (%s) %s @ %s:%d\n", 787 class->lc_name, lock->lo_name, file, line); 788 printf("while exclusively locked from %s:%d\n", 789 lock1->li_file, lock1->li_line); 790 panic("share->excl"); 791 } 792 if ((lock1->li_flags & LI_EXCLUSIVE) == 0 && 793 (flags & LOP_EXCLUSIVE) != 0) { 794 printf("exclusive lock of (%s) %s @ %s:%d\n", 795 class->lc_name, lock->lo_name, file, line); 796 printf("while share locked from %s:%d\n", 797 lock1->li_file, lock1->li_line); 798 panic("excl->share"); 799 } 800 return; 801 } 802 803 /* 804 * Try locks do not block if they fail to acquire the lock, thus 805 * there is no danger of deadlocks or of switching while holding a 806 * spin lock if we acquire a lock via a try operation. 807 */ 808 if (flags & LOP_TRYLOCK) 809 return; 810 811 /* 812 * Check for duplicate locks of the same type. Note that we only 813 * have to check for this on the last lock we just acquired. Any 814 * other cases will be caught as lock order violations. 815 */ 816 lock1 = &(*lock_list)->ll_children[(*lock_list)->ll_count - 1]; 817 w1 = lock1->li_lock->lo_witness; 818 if (w1 == w) { 819 if (w->w_same_squawked || (lock->lo_flags & LO_DUPOK) || 820 (flags & LOP_DUPOK)) 821 return; 822 w->w_same_squawked = 1; 823 printf("acquiring duplicate lock of same type: \"%s\"\n", 824 lock->lo_type); 825 printf(" 1st %s @ %s:%d\n", lock1->li_lock->lo_name, 826 lock1->li_file, lock1->li_line); 827 printf(" 2nd %s @ %s:%d\n", lock->lo_name, file, line); 828 #ifdef KDB 829 goto debugger; 830 #else 831 return; 832 #endif 833 } 834 MPASS(!mtx_owned(&w_mtx)); 835 mtx_lock_spin(&w_mtx); 836 /* 837 * If we have a known higher number just say ok 838 */ 839 if (witness_watch > 1 && w->w_level > w1->w_level) { 840 mtx_unlock_spin(&w_mtx); 841 return; 842 } 843 /* 844 * If we know that the the lock we are acquiring comes after 845 * the lock we most recently acquired in the lock order tree, 846 * then there is no need for any further checks. 847 */ 848 if (isitmydescendant(w1, w)) { 849 mtx_unlock_spin(&w_mtx); 850 return; 851 } 852 for (j = 0, lle = *lock_list; lle != NULL; lle = lle->ll_next) { 853 for (i = lle->ll_count - 1; i >= 0; i--, j++) { 854 855 MPASS(j < WITNESS_COUNT); 856 lock1 = &lle->ll_children[i]; 857 w1 = lock1->li_lock->lo_witness; 858 859 /* 860 * If this lock doesn't undergo witness checking, 861 * then skip it. 862 */ 863 if (w1 == NULL) { 864 KASSERT((lock1->li_lock->lo_flags & LO_WITNESS) == 0, 865 ("lock missing witness structure")); 866 continue; 867 } 868 /* 869 * If we are locking Giant and this is a sleepable 870 * lock, then skip it. 871 */ 872 if ((lock1->li_lock->lo_flags & LO_SLEEPABLE) != 0 && 873 lock == &Giant.mtx_object) 874 continue; 875 /* 876 * If we are locking a sleepable lock and this lock 877 * is Giant, then skip it. 878 */ 879 if ((lock->lo_flags & LO_SLEEPABLE) != 0 && 880 lock1->li_lock == &Giant.mtx_object) 881 continue; 882 /* 883 * If we are locking a sleepable lock and this lock 884 * isn't sleepable, we want to treat it as a lock 885 * order violation to enfore a general lock order of 886 * sleepable locks before non-sleepable locks. 887 */ 888 if (((lock->lo_flags & LO_SLEEPABLE) != 0 && 889 (lock1->li_lock->lo_flags & LO_SLEEPABLE) == 0)) 890 goto reversal; 891 /* 892 * Check the lock order hierarchy for a reveresal. 893 */ 894 if (!isitmydescendant(w, w1)) 895 continue; 896 reversal: 897 /* 898 * We have a lock order violation, check to see if it 899 * is allowed or has already been yelled about. 900 */ 901 mtx_unlock_spin(&w_mtx); 902 #ifdef BLESSING 903 /* 904 * If the lock order is blessed, just bail. We don't 905 * look for other lock order violations though, which 906 * may be a bug. 907 */ 908 if (blessed(w, w1)) 909 return; 910 #endif 911 if (lock1->li_lock == &Giant.mtx_object) { 912 if (w1->w_Giant_squawked) 913 return; 914 else 915 w1->w_Giant_squawked = 1; 916 } else { 917 if (w1->w_other_squawked) 918 return; 919 else 920 w1->w_other_squawked = 1; 921 } 922 /* 923 * Ok, yell about it. 924 */ 925 printf("lock order reversal\n"); 926 /* 927 * Try to locate an earlier lock with 928 * witness w in our list. 929 */ 930 do { 931 lock2 = &lle->ll_children[i]; 932 MPASS(lock2->li_lock != NULL); 933 if (lock2->li_lock->lo_witness == w) 934 break; 935 if (i == 0 && lle->ll_next != NULL) { 936 lle = lle->ll_next; 937 i = lle->ll_count - 1; 938 MPASS(i >= 0 && i < LOCK_NCHILDREN); 939 } else 940 i--; 941 } while (i >= 0); 942 if (i < 0) { 943 printf(" 1st %p %s (%s) @ %s:%d\n", 944 lock1->li_lock, lock1->li_lock->lo_name, 945 lock1->li_lock->lo_type, lock1->li_file, 946 lock1->li_line); 947 printf(" 2nd %p %s (%s) @ %s:%d\n", lock, 948 lock->lo_name, lock->lo_type, file, line); 949 } else { 950 printf(" 1st %p %s (%s) @ %s:%d\n", 951 lock2->li_lock, lock2->li_lock->lo_name, 952 lock2->li_lock->lo_type, lock2->li_file, 953 lock2->li_line); 954 printf(" 2nd %p %s (%s) @ %s:%d\n", 955 lock1->li_lock, lock1->li_lock->lo_name, 956 lock1->li_lock->lo_type, lock1->li_file, 957 lock1->li_line); 958 printf(" 3rd %p %s (%s) @ %s:%d\n", lock, 959 lock->lo_name, lock->lo_type, file, line); 960 } 961 #ifdef KDB 962 goto debugger; 963 #else 964 return; 965 #endif 966 } 967 } 968 lock1 = &(*lock_list)->ll_children[(*lock_list)->ll_count - 1]; 969 /* 970 * If requested, build a new lock order. However, don't build a new 971 * relationship between a sleepable lock and Giant if it is in the 972 * wrong direction. The correct lock order is that sleepable locks 973 * always come before Giant. 974 */ 975 if (flags & LOP_NEWORDER && 976 !(lock1->li_lock == &Giant.mtx_object && 977 (lock->lo_flags & LO_SLEEPABLE) != 0)) { 978 CTR3(KTR_WITNESS, "%s: adding %s as a child of %s", __func__, 979 lock->lo_type, lock1->li_lock->lo_type); 980 if (!itismychild(lock1->li_lock->lo_witness, w)) 981 /* Witness is dead. */ 982 return; 983 } 984 mtx_unlock_spin(&w_mtx); 985 return; 986 987 #ifdef KDB 988 debugger: 989 if (witness_trace) 990 kdb_backtrace(); 991 if (witness_kdb) 992 kdb_enter(__func__); 993 #endif 994 } 995 996 void 997 witness_lock(struct lock_object *lock, int flags, const char *file, int line) 998 { 999 struct lock_list_entry **lock_list, *lle; 1000 struct lock_instance *instance; 1001 struct witness *w; 1002 struct thread *td; 1003 1004 if (witness_cold || witness_watch == 0 || lock->lo_witness == NULL || 1005 panicstr != NULL) 1006 return; 1007 w = lock->lo_witness; 1008 td = curthread; 1009 file = fixup_filename(file); 1010 1011 /* Determine lock list for this lock. */ 1012 if (lock->lo_class->lc_flags & LC_SLEEPLOCK) 1013 lock_list = &td->td_sleeplocks; 1014 else 1015 lock_list = PCPU_PTR(spinlocks); 1016 1017 /* Check to see if we are recursing on a lock we already own. */ 1018 instance = find_instance(*lock_list, lock); 1019 if (instance != NULL) { 1020 instance->li_flags++; 1021 CTR4(KTR_WITNESS, "%s: pid %d recursed on %s r=%d", __func__, 1022 td->td_proc->p_pid, lock->lo_name, 1023 instance->li_flags & LI_RECURSEMASK); 1024 instance->li_file = file; 1025 instance->li_line = line; 1026 return; 1027 } 1028 1029 /* Update per-witness last file and line acquire. */ 1030 w->w_file = file; 1031 w->w_line = line; 1032 1033 /* Find the next open lock instance in the list and fill it. */ 1034 lle = *lock_list; 1035 if (lle == NULL || lle->ll_count == LOCK_NCHILDREN) { 1036 lle = witness_lock_list_get(); 1037 if (lle == NULL) 1038 return; 1039 lle->ll_next = *lock_list; 1040 CTR3(KTR_WITNESS, "%s: pid %d added lle %p", __func__, 1041 td->td_proc->p_pid, lle); 1042 *lock_list = lle; 1043 } 1044 instance = &lle->ll_children[lle->ll_count++]; 1045 instance->li_lock = lock; 1046 instance->li_line = line; 1047 instance->li_file = file; 1048 if ((flags & LOP_EXCLUSIVE) != 0) 1049 instance->li_flags = LI_EXCLUSIVE; 1050 else 1051 instance->li_flags = 0; 1052 CTR4(KTR_WITNESS, "%s: pid %d added %s as lle[%d]", __func__, 1053 td->td_proc->p_pid, lock->lo_name, lle->ll_count - 1); 1054 } 1055 1056 void 1057 witness_upgrade(struct lock_object *lock, int flags, const char *file, int line) 1058 { 1059 struct lock_instance *instance; 1060 struct lock_class *class; 1061 1062 KASSERT(!witness_cold, ("%s: witness_cold", __func__)); 1063 if (lock->lo_witness == NULL || witness_watch == 0 || panicstr != NULL) 1064 return; 1065 class = lock->lo_class; 1066 file = fixup_filename(file); 1067 if ((lock->lo_flags & LO_UPGRADABLE) == 0) 1068 panic("upgrade of non-upgradable lock (%s) %s @ %s:%d", 1069 class->lc_name, lock->lo_name, file, line); 1070 if ((flags & LOP_TRYLOCK) == 0) 1071 panic("non-try upgrade of lock (%s) %s @ %s:%d", class->lc_name, 1072 lock->lo_name, file, line); 1073 if ((lock->lo_class->lc_flags & LC_SLEEPLOCK) == 0) 1074 panic("upgrade of non-sleep lock (%s) %s @ %s:%d", 1075 class->lc_name, lock->lo_name, file, line); 1076 instance = find_instance(curthread->td_sleeplocks, lock); 1077 if (instance == NULL) 1078 panic("upgrade of unlocked lock (%s) %s @ %s:%d", 1079 class->lc_name, lock->lo_name, file, line); 1080 if ((instance->li_flags & LI_EXCLUSIVE) != 0) 1081 panic("upgrade of exclusive lock (%s) %s @ %s:%d", 1082 class->lc_name, lock->lo_name, file, line); 1083 if ((instance->li_flags & LI_RECURSEMASK) != 0) 1084 panic("upgrade of recursed lock (%s) %s r=%d @ %s:%d", 1085 class->lc_name, lock->lo_name, 1086 instance->li_flags & LI_RECURSEMASK, file, line); 1087 instance->li_flags |= LI_EXCLUSIVE; 1088 } 1089 1090 void 1091 witness_downgrade(struct lock_object *lock, int flags, const char *file, 1092 int line) 1093 { 1094 struct lock_instance *instance; 1095 struct lock_class *class; 1096 1097 KASSERT(!witness_cold, ("%s: witness_cold", __func__)); 1098 if (lock->lo_witness == NULL || witness_watch == 0 || panicstr != NULL) 1099 return; 1100 class = lock->lo_class; 1101 file = fixup_filename(file); 1102 if ((lock->lo_flags & LO_UPGRADABLE) == 0) 1103 panic("downgrade of non-upgradable lock (%s) %s @ %s:%d", 1104 class->lc_name, lock->lo_name, file, line); 1105 if ((lock->lo_class->lc_flags & LC_SLEEPLOCK) == 0) 1106 panic("downgrade of non-sleep lock (%s) %s @ %s:%d", 1107 class->lc_name, lock->lo_name, file, line); 1108 instance = find_instance(curthread->td_sleeplocks, lock); 1109 if (instance == NULL) 1110 panic("downgrade of unlocked lock (%s) %s @ %s:%d", 1111 class->lc_name, lock->lo_name, file, line); 1112 if ((instance->li_flags & LI_EXCLUSIVE) == 0) 1113 panic("downgrade of shared lock (%s) %s @ %s:%d", 1114 class->lc_name, lock->lo_name, file, line); 1115 if ((instance->li_flags & LI_RECURSEMASK) != 0) 1116 panic("downgrade of recursed lock (%s) %s r=%d @ %s:%d", 1117 class->lc_name, lock->lo_name, 1118 instance->li_flags & LI_RECURSEMASK, file, line); 1119 instance->li_flags &= ~LI_EXCLUSIVE; 1120 } 1121 1122 void 1123 witness_unlock(struct lock_object *lock, int flags, const char *file, int line) 1124 { 1125 struct lock_list_entry **lock_list, *lle; 1126 struct lock_instance *instance; 1127 struct lock_class *class; 1128 struct thread *td; 1129 register_t s; 1130 int i, j; 1131 1132 if (witness_cold || witness_watch == 0 || lock->lo_witness == NULL || 1133 panicstr != NULL) 1134 return; 1135 td = curthread; 1136 class = lock->lo_class; 1137 file = fixup_filename(file); 1138 1139 /* Find lock instance associated with this lock. */ 1140 if (class->lc_flags & LC_SLEEPLOCK) 1141 lock_list = &td->td_sleeplocks; 1142 else 1143 lock_list = PCPU_PTR(spinlocks); 1144 for (; *lock_list != NULL; lock_list = &(*lock_list)->ll_next) 1145 for (i = 0; i < (*lock_list)->ll_count; i++) { 1146 instance = &(*lock_list)->ll_children[i]; 1147 if (instance->li_lock == lock) 1148 goto found; 1149 } 1150 panic("lock (%s) %s not locked @ %s:%d", class->lc_name, lock->lo_name, 1151 file, line); 1152 found: 1153 1154 /* First, check for shared/exclusive mismatches. */ 1155 if ((instance->li_flags & LI_EXCLUSIVE) != 0 && 1156 (flags & LOP_EXCLUSIVE) == 0) { 1157 printf("shared unlock of (%s) %s @ %s:%d\n", class->lc_name, 1158 lock->lo_name, file, line); 1159 printf("while exclusively locked from %s:%d\n", 1160 instance->li_file, instance->li_line); 1161 panic("excl->ushare"); 1162 } 1163 if ((instance->li_flags & LI_EXCLUSIVE) == 0 && 1164 (flags & LOP_EXCLUSIVE) != 0) { 1165 printf("exclusive unlock of (%s) %s @ %s:%d\n", class->lc_name, 1166 lock->lo_name, file, line); 1167 printf("while share locked from %s:%d\n", instance->li_file, 1168 instance->li_line); 1169 panic("share->uexcl"); 1170 } 1171 1172 /* If we are recursed, unrecurse. */ 1173 if ((instance->li_flags & LI_RECURSEMASK) > 0) { 1174 CTR4(KTR_WITNESS, "%s: pid %d unrecursed on %s r=%d", __func__, 1175 td->td_proc->p_pid, instance->li_lock->lo_name, 1176 instance->li_flags); 1177 instance->li_flags--; 1178 return; 1179 } 1180 1181 /* Otherwise, remove this item from the list. */ 1182 s = intr_disable(); 1183 CTR4(KTR_WITNESS, "%s: pid %d removed %s from lle[%d]", __func__, 1184 td->td_proc->p_pid, instance->li_lock->lo_name, 1185 (*lock_list)->ll_count - 1); 1186 for (j = i; j < (*lock_list)->ll_count - 1; j++) 1187 (*lock_list)->ll_children[j] = 1188 (*lock_list)->ll_children[j + 1]; 1189 (*lock_list)->ll_count--; 1190 intr_restore(s); 1191 1192 /* If this lock list entry is now empty, free it. */ 1193 if ((*lock_list)->ll_count == 0) { 1194 lle = *lock_list; 1195 *lock_list = lle->ll_next; 1196 CTR3(KTR_WITNESS, "%s: pid %d removed lle %p", __func__, 1197 td->td_proc->p_pid, lle); 1198 witness_lock_list_free(lle); 1199 } 1200 } 1201 1202 /* 1203 * Warn if any locks other than 'lock' are held. Flags can be passed in to 1204 * exempt Giant and sleepable locks from the checks as well. If any 1205 * non-exempt locks are held, then a supplied message is printed to the 1206 * console along with a list of the offending locks. If indicated in the 1207 * flags then a failure results in a panic as well. 1208 */ 1209 int 1210 witness_warn(int flags, struct lock_object *lock, const char *fmt, ...) 1211 { 1212 struct lock_list_entry *lle; 1213 struct lock_instance *lock1; 1214 struct thread *td; 1215 va_list ap; 1216 int i, n; 1217 1218 if (witness_cold || witness_watch == 0 || panicstr != NULL) 1219 return (0); 1220 n = 0; 1221 td = curthread; 1222 for (lle = td->td_sleeplocks; lle != NULL; lle = lle->ll_next) 1223 for (i = lle->ll_count - 1; i >= 0; i--) { 1224 lock1 = &lle->ll_children[i]; 1225 if (lock1->li_lock == lock) 1226 continue; 1227 if (flags & WARN_GIANTOK && 1228 lock1->li_lock == &Giant.mtx_object) 1229 continue; 1230 if (flags & WARN_SLEEPOK && 1231 (lock1->li_lock->lo_flags & LO_SLEEPABLE) != 0) 1232 continue; 1233 if (n == 0) { 1234 va_start(ap, fmt); 1235 vprintf(fmt, ap); 1236 va_end(ap); 1237 printf(" with the following"); 1238 if (flags & WARN_SLEEPOK) 1239 printf(" non-sleepable"); 1240 printf(" locks held:\n"); 1241 } 1242 n++; 1243 witness_list_lock(lock1); 1244 } 1245 if (PCPU_GET(spinlocks) != NULL) { 1246 /* 1247 * Since we already hold a spinlock preemption is 1248 * already blocked. 1249 */ 1250 if (n == 0) { 1251 va_start(ap, fmt); 1252 vprintf(fmt, ap); 1253 va_end(ap); 1254 printf(" with the following"); 1255 if (flags & WARN_SLEEPOK) 1256 printf(" non-sleepable"); 1257 printf(" locks held:\n"); 1258 } 1259 n += witness_list_locks(PCPU_PTR(spinlocks)); 1260 } 1261 if (flags & WARN_PANIC && n) 1262 panic("witness_warn"); 1263 #ifdef KDB 1264 else if (witness_kdb && n) 1265 kdb_enter(__func__); 1266 else if (witness_trace && n) 1267 kdb_backtrace(); 1268 #endif 1269 return (n); 1270 } 1271 1272 const char * 1273 witness_file(struct lock_object *lock) 1274 { 1275 struct witness *w; 1276 1277 if (witness_cold || witness_watch == 0 || lock->lo_witness == NULL) 1278 return ("?"); 1279 w = lock->lo_witness; 1280 return (w->w_file); 1281 } 1282 1283 int 1284 witness_line(struct lock_object *lock) 1285 { 1286 struct witness *w; 1287 1288 if (witness_cold || witness_watch == 0 || lock->lo_witness == NULL) 1289 return (0); 1290 w = lock->lo_witness; 1291 return (w->w_line); 1292 } 1293 1294 static struct witness * 1295 enroll(const char *description, struct lock_class *lock_class) 1296 { 1297 struct witness *w; 1298 1299 if (witness_watch == 0 || panicstr != NULL) 1300 return (NULL); 1301 if ((lock_class->lc_flags & LC_SPINLOCK) && witness_skipspin) 1302 return (NULL); 1303 mtx_lock_spin(&w_mtx); 1304 STAILQ_FOREACH(w, &w_all, w_list) { 1305 if (w->w_name == description || (w->w_refcount > 0 && 1306 strcmp(description, w->w_name) == 0)) { 1307 w->w_refcount++; 1308 mtx_unlock_spin(&w_mtx); 1309 if (lock_class != w->w_class) 1310 panic( 1311 "lock (%s) %s does not match earlier (%s) lock", 1312 description, lock_class->lc_name, 1313 w->w_class->lc_name); 1314 return (w); 1315 } 1316 } 1317 /* 1318 * We issue a warning for any spin locks not defined in the static 1319 * order list as a way to discourage their use (folks should really 1320 * be using non-spin mutexes most of the time). However, several 1321 * 3rd part device drivers use spin locks because that is all they 1322 * have available on Windows and Linux and they think that normal 1323 * mutexes are insufficient. 1324 */ 1325 if ((lock_class->lc_flags & LC_SPINLOCK) && witness_spin_warn) 1326 printf("WITNESS: spin lock %s not in order list", description); 1327 if ((w = witness_get()) == NULL) 1328 return (NULL); 1329 w->w_name = description; 1330 w->w_class = lock_class; 1331 w->w_refcount = 1; 1332 STAILQ_INSERT_HEAD(&w_all, w, w_list); 1333 if (lock_class->lc_flags & LC_SPINLOCK) 1334 STAILQ_INSERT_HEAD(&w_spin, w, w_typelist); 1335 else if (lock_class->lc_flags & LC_SLEEPLOCK) 1336 STAILQ_INSERT_HEAD(&w_sleep, w, w_typelist); 1337 else { 1338 mtx_unlock_spin(&w_mtx); 1339 panic("lock class %s is not sleep or spin", 1340 lock_class->lc_name); 1341 } 1342 mtx_unlock_spin(&w_mtx); 1343 return (w); 1344 } 1345 1346 /* Don't let the door bang you on the way out... */ 1347 static int 1348 depart(struct witness *w) 1349 { 1350 struct witness_child_list_entry *wcl, *nwcl; 1351 struct witness_list *list; 1352 struct witness *parent; 1353 1354 MPASS(w->w_refcount == 0); 1355 if (w->w_class->lc_flags & LC_SLEEPLOCK) 1356 list = &w_sleep; 1357 else 1358 list = &w_spin; 1359 /* 1360 * First, we run through the entire tree looking for any 1361 * witnesses that the outgoing witness is a child of. For 1362 * each parent that we find, we reparent all the direct 1363 * children of the outgoing witness to its parent. 1364 */ 1365 STAILQ_FOREACH(parent, list, w_typelist) { 1366 if (!isitmychild(parent, w)) 1367 continue; 1368 removechild(parent, w); 1369 if (!reparentchildren(parent, w)) 1370 return (0); 1371 } 1372 1373 /* 1374 * Now we go through and free up the child list of the 1375 * outgoing witness. 1376 */ 1377 for (wcl = w->w_children; wcl != NULL; wcl = nwcl) { 1378 nwcl = wcl->wcl_next; 1379 witness_child_free(wcl); 1380 } 1381 1382 /* 1383 * Detach from various lists and free. 1384 */ 1385 STAILQ_REMOVE(list, w, witness, w_typelist); 1386 STAILQ_REMOVE(&w_all, w, witness, w_list); 1387 witness_free(w); 1388 1389 /* Finally, fixup the tree. */ 1390 return (rebalancetree(list)); 1391 } 1392 1393 /* 1394 * Prune an entire lock order tree. We look for cases where a lock 1395 * is now both a descendant and a direct child of a given lock. In 1396 * that case, we want to remove the direct child link from the tree. 1397 * 1398 * Returns false if insertchild() fails. 1399 */ 1400 static int 1401 rebalancetree(struct witness_list *list) 1402 { 1403 struct witness *child, *parent; 1404 1405 STAILQ_FOREACH(child, list, w_typelist) { 1406 STAILQ_FOREACH(parent, list, w_typelist) { 1407 if (!isitmychild(parent, child)) 1408 continue; 1409 removechild(parent, child); 1410 if (isitmydescendant(parent, child)) 1411 continue; 1412 if (!insertchild(parent, child)) 1413 return (0); 1414 } 1415 } 1416 witness_levelall(); 1417 return (1); 1418 } 1419 1420 /* 1421 * Add "child" as a direct child of "parent". Returns false if 1422 * we fail due to out of memory. 1423 */ 1424 static int 1425 insertchild(struct witness *parent, struct witness *child) 1426 { 1427 struct witness_child_list_entry **wcl; 1428 1429 MPASS(child != NULL && parent != NULL); 1430 1431 /* 1432 * Insert "child" after "parent" 1433 */ 1434 wcl = &parent->w_children; 1435 while (*wcl != NULL && (*wcl)->wcl_count == WITNESS_NCHILDREN) 1436 wcl = &(*wcl)->wcl_next; 1437 if (*wcl == NULL) { 1438 *wcl = witness_child_get(); 1439 if (*wcl == NULL) 1440 return (0); 1441 } 1442 (*wcl)->wcl_children[(*wcl)->wcl_count++] = child; 1443 1444 return (1); 1445 } 1446 1447 /* 1448 * Make all the direct descendants of oldparent be direct descendants 1449 * of newparent. 1450 */ 1451 static int 1452 reparentchildren(struct witness *newparent, struct witness *oldparent) 1453 { 1454 struct witness_child_list_entry *wcl; 1455 int i; 1456 1457 /* Avoid making a witness a child of itself. */ 1458 MPASS(!isitmychild(oldparent, newparent)); 1459 1460 for (wcl = oldparent->w_children; wcl != NULL; wcl = wcl->wcl_next) 1461 for (i = 0; i < wcl->wcl_count; i++) 1462 if (!insertchild(newparent, wcl->wcl_children[i])) 1463 return (0); 1464 return (1); 1465 } 1466 1467 static int 1468 itismychild(struct witness *parent, struct witness *child) 1469 { 1470 struct witness_list *list; 1471 1472 MPASS(child != NULL && parent != NULL); 1473 if ((parent->w_class->lc_flags & (LC_SLEEPLOCK | LC_SPINLOCK)) != 1474 (child->w_class->lc_flags & (LC_SLEEPLOCK | LC_SPINLOCK))) 1475 panic( 1476 "%s: parent (%s) and child (%s) are not the same lock type", 1477 __func__, parent->w_class->lc_name, 1478 child->w_class->lc_name); 1479 1480 if (!insertchild(parent, child)) 1481 return (0); 1482 1483 if (parent->w_class->lc_flags & LC_SLEEPLOCK) 1484 list = &w_sleep; 1485 else 1486 list = &w_spin; 1487 return (rebalancetree(list)); 1488 } 1489 1490 static void 1491 removechild(struct witness *parent, struct witness *child) 1492 { 1493 struct witness_child_list_entry **wcl, *wcl1; 1494 int i; 1495 1496 for (wcl = &parent->w_children; *wcl != NULL; wcl = &(*wcl)->wcl_next) 1497 for (i = 0; i < (*wcl)->wcl_count; i++) 1498 if ((*wcl)->wcl_children[i] == child) 1499 goto found; 1500 return; 1501 found: 1502 (*wcl)->wcl_count--; 1503 if ((*wcl)->wcl_count > i) 1504 (*wcl)->wcl_children[i] = 1505 (*wcl)->wcl_children[(*wcl)->wcl_count]; 1506 MPASS((*wcl)->wcl_children[i] != NULL); 1507 if ((*wcl)->wcl_count != 0) 1508 return; 1509 wcl1 = *wcl; 1510 *wcl = wcl1->wcl_next; 1511 witness_child_free(wcl1); 1512 } 1513 1514 static int 1515 isitmychild(struct witness *parent, struct witness *child) 1516 { 1517 struct witness_child_list_entry *wcl; 1518 int i; 1519 1520 for (wcl = parent->w_children; wcl != NULL; wcl = wcl->wcl_next) { 1521 for (i = 0; i < wcl->wcl_count; i++) { 1522 if (wcl->wcl_children[i] == child) 1523 return (1); 1524 } 1525 } 1526 return (0); 1527 } 1528 1529 static int 1530 isitmydescendant(struct witness *parent, struct witness *child) 1531 { 1532 struct witness_child_list_entry *wcl; 1533 int i, j; 1534 1535 if (isitmychild(parent, child)) 1536 return (1); 1537 j = 0; 1538 for (wcl = parent->w_children; wcl != NULL; wcl = wcl->wcl_next) { 1539 MPASS(j < 1000); 1540 for (i = 0; i < wcl->wcl_count; i++) { 1541 if (isitmydescendant(wcl->wcl_children[i], child)) 1542 return (1); 1543 } 1544 j++; 1545 } 1546 return (0); 1547 } 1548 1549 static void 1550 witness_levelall (void) 1551 { 1552 struct witness_list *list; 1553 struct witness *w, *w1; 1554 1555 /* 1556 * First clear all levels. 1557 */ 1558 STAILQ_FOREACH(w, &w_all, w_list) { 1559 w->w_level = 0; 1560 } 1561 1562 /* 1563 * Look for locks with no parent and level all their descendants. 1564 */ 1565 STAILQ_FOREACH(w, &w_all, w_list) { 1566 /* 1567 * This is just an optimization, technically we could get 1568 * away just walking the all list each time. 1569 */ 1570 if (w->w_class->lc_flags & LC_SLEEPLOCK) 1571 list = &w_sleep; 1572 else 1573 list = &w_spin; 1574 STAILQ_FOREACH(w1, list, w_typelist) { 1575 if (isitmychild(w1, w)) 1576 goto skip; 1577 } 1578 witness_leveldescendents(w, 0); 1579 skip: 1580 ; /* silence GCC 3.x */ 1581 } 1582 } 1583 1584 static void 1585 witness_leveldescendents(struct witness *parent, int level) 1586 { 1587 struct witness_child_list_entry *wcl; 1588 int i; 1589 1590 if (parent->w_level < level) 1591 parent->w_level = level; 1592 level++; 1593 for (wcl = parent->w_children; wcl != NULL; wcl = wcl->wcl_next) 1594 for (i = 0; i < wcl->wcl_count; i++) 1595 witness_leveldescendents(wcl->wcl_children[i], level); 1596 } 1597 1598 static void 1599 witness_displaydescendants(void(*prnt)(const char *fmt, ...), 1600 struct witness *parent, int indent) 1601 { 1602 struct witness_child_list_entry *wcl; 1603 int i, level; 1604 1605 level = parent->w_level; 1606 prnt("%-2d", level); 1607 for (i = 0; i < indent; i++) 1608 prnt(" "); 1609 if (parent->w_refcount > 0) 1610 prnt("%s", parent->w_name); 1611 else 1612 prnt("(dead)"); 1613 if (parent->w_displayed) { 1614 prnt(" -- (already displayed)\n"); 1615 return; 1616 } 1617 parent->w_displayed = 1; 1618 if (parent->w_refcount > 0) { 1619 if (parent->w_file != NULL) 1620 prnt(" -- last acquired @ %s:%d", parent->w_file, 1621 parent->w_line); 1622 } 1623 prnt("\n"); 1624 for (wcl = parent->w_children; wcl != NULL; wcl = wcl->wcl_next) 1625 for (i = 0; i < wcl->wcl_count; i++) 1626 witness_displaydescendants(prnt, 1627 wcl->wcl_children[i], indent + 1); 1628 } 1629 1630 #ifdef BLESSING 1631 static int 1632 blessed(struct witness *w1, struct witness *w2) 1633 { 1634 int i; 1635 struct witness_blessed *b; 1636 1637 for (i = 0; i < blessed_count; i++) { 1638 b = &blessed_list[i]; 1639 if (strcmp(w1->w_name, b->b_lock1) == 0) { 1640 if (strcmp(w2->w_name, b->b_lock2) == 0) 1641 return (1); 1642 continue; 1643 } 1644 if (strcmp(w1->w_name, b->b_lock2) == 0) 1645 if (strcmp(w2->w_name, b->b_lock1) == 0) 1646 return (1); 1647 } 1648 return (0); 1649 } 1650 #endif 1651 1652 static struct witness * 1653 witness_get(void) 1654 { 1655 struct witness *w; 1656 1657 if (witness_watch == 0) { 1658 mtx_unlock_spin(&w_mtx); 1659 return (NULL); 1660 } 1661 if (STAILQ_EMPTY(&w_free)) { 1662 witness_watch = 0; 1663 mtx_unlock_spin(&w_mtx); 1664 printf("%s: witness exhausted\n", __func__); 1665 return (NULL); 1666 } 1667 w = STAILQ_FIRST(&w_free); 1668 STAILQ_REMOVE_HEAD(&w_free, w_list); 1669 bzero(w, sizeof(*w)); 1670 return (w); 1671 } 1672 1673 static void 1674 witness_free(struct witness *w) 1675 { 1676 1677 STAILQ_INSERT_HEAD(&w_free, w, w_list); 1678 } 1679 1680 static struct witness_child_list_entry * 1681 witness_child_get(void) 1682 { 1683 struct witness_child_list_entry *wcl; 1684 1685 if (witness_watch == 0) { 1686 mtx_unlock_spin(&w_mtx); 1687 return (NULL); 1688 } 1689 wcl = w_child_free; 1690 if (wcl == NULL) { 1691 witness_watch = 0; 1692 mtx_unlock_spin(&w_mtx); 1693 printf("%s: witness exhausted\n", __func__); 1694 return (NULL); 1695 } 1696 w_child_free = wcl->wcl_next; 1697 bzero(wcl, sizeof(*wcl)); 1698 return (wcl); 1699 } 1700 1701 static void 1702 witness_child_free(struct witness_child_list_entry *wcl) 1703 { 1704 1705 wcl->wcl_next = w_child_free; 1706 w_child_free = wcl; 1707 } 1708 1709 static struct lock_list_entry * 1710 witness_lock_list_get(void) 1711 { 1712 struct lock_list_entry *lle; 1713 1714 if (witness_watch == 0) 1715 return (NULL); 1716 mtx_lock_spin(&w_mtx); 1717 lle = w_lock_list_free; 1718 if (lle == NULL) { 1719 witness_watch = 0; 1720 mtx_unlock_spin(&w_mtx); 1721 printf("%s: witness exhausted\n", __func__); 1722 return (NULL); 1723 } 1724 w_lock_list_free = lle->ll_next; 1725 mtx_unlock_spin(&w_mtx); 1726 bzero(lle, sizeof(*lle)); 1727 return (lle); 1728 } 1729 1730 static void 1731 witness_lock_list_free(struct lock_list_entry *lle) 1732 { 1733 1734 mtx_lock_spin(&w_mtx); 1735 lle->ll_next = w_lock_list_free; 1736 w_lock_list_free = lle; 1737 mtx_unlock_spin(&w_mtx); 1738 } 1739 1740 static struct lock_instance * 1741 find_instance(struct lock_list_entry *lock_list, struct lock_object *lock) 1742 { 1743 struct lock_list_entry *lle; 1744 struct lock_instance *instance; 1745 int i; 1746 1747 for (lle = lock_list; lle != NULL; lle = lle->ll_next) 1748 for (i = lle->ll_count - 1; i >= 0; i--) { 1749 instance = &lle->ll_children[i]; 1750 if (instance->li_lock == lock) 1751 return (instance); 1752 } 1753 return (NULL); 1754 } 1755 1756 static void 1757 witness_list_lock(struct lock_instance *instance) 1758 { 1759 struct lock_object *lock; 1760 1761 lock = instance->li_lock; 1762 printf("%s %s %s", (instance->li_flags & LI_EXCLUSIVE) != 0 ? 1763 "exclusive" : "shared", lock->lo_class->lc_name, lock->lo_name); 1764 if (lock->lo_type != lock->lo_name) 1765 printf(" (%s)", lock->lo_type); 1766 printf(" r = %d (%p) locked @ %s:%d\n", 1767 instance->li_flags & LI_RECURSEMASK, lock, instance->li_file, 1768 instance->li_line); 1769 } 1770 1771 #ifdef DDB 1772 static int 1773 witness_thread_has_locks(struct thread *td) 1774 { 1775 1776 return (td->td_sleeplocks != NULL); 1777 } 1778 1779 static int 1780 witness_proc_has_locks(struct proc *p) 1781 { 1782 struct thread *td; 1783 1784 FOREACH_THREAD_IN_PROC(p, td) { 1785 if (witness_thread_has_locks(td)) 1786 return (1); 1787 } 1788 return (0); 1789 } 1790 #endif 1791 1792 int 1793 witness_list_locks(struct lock_list_entry **lock_list) 1794 { 1795 struct lock_list_entry *lle; 1796 int i, nheld; 1797 1798 nheld = 0; 1799 for (lle = *lock_list; lle != NULL; lle = lle->ll_next) 1800 for (i = lle->ll_count - 1; i >= 0; i--) { 1801 witness_list_lock(&lle->ll_children[i]); 1802 nheld++; 1803 } 1804 return (nheld); 1805 } 1806 1807 /* 1808 * This is a bit risky at best. We call this function when we have timed 1809 * out acquiring a spin lock, and we assume that the other CPU is stuck 1810 * with this lock held. So, we go groveling around in the other CPU's 1811 * per-cpu data to try to find the lock instance for this spin lock to 1812 * see when it was last acquired. 1813 */ 1814 void 1815 witness_display_spinlock(struct lock_object *lock, struct thread *owner) 1816 { 1817 struct lock_instance *instance; 1818 struct pcpu *pc; 1819 1820 if (owner->td_critnest == 0 || owner->td_oncpu == NOCPU) 1821 return; 1822 pc = pcpu_find(owner->td_oncpu); 1823 instance = find_instance(pc->pc_spinlocks, lock); 1824 if (instance != NULL) 1825 witness_list_lock(instance); 1826 } 1827 1828 void 1829 witness_save(struct lock_object *lock, const char **filep, int *linep) 1830 { 1831 struct lock_instance *instance; 1832 1833 KASSERT(!witness_cold, ("%s: witness_cold", __func__)); 1834 if (lock->lo_witness == NULL || witness_watch == 0 || panicstr != NULL) 1835 return; 1836 if ((lock->lo_class->lc_flags & LC_SLEEPLOCK) == 0) 1837 panic("%s: lock (%s) %s is not a sleep lock", __func__, 1838 lock->lo_class->lc_name, lock->lo_name); 1839 instance = find_instance(curthread->td_sleeplocks, lock); 1840 if (instance == NULL) 1841 panic("%s: lock (%s) %s not locked", __func__, 1842 lock->lo_class->lc_name, lock->lo_name); 1843 *filep = instance->li_file; 1844 *linep = instance->li_line; 1845 } 1846 1847 void 1848 witness_restore(struct lock_object *lock, const char *file, int line) 1849 { 1850 struct lock_instance *instance; 1851 1852 KASSERT(!witness_cold, ("%s: witness_cold", __func__)); 1853 if (lock->lo_witness == NULL || witness_watch == 0 || panicstr != NULL) 1854 return; 1855 if ((lock->lo_class->lc_flags & LC_SLEEPLOCK) == 0) 1856 panic("%s: lock (%s) %s is not a sleep lock", __func__, 1857 lock->lo_class->lc_name, lock->lo_name); 1858 instance = find_instance(curthread->td_sleeplocks, lock); 1859 if (instance == NULL) 1860 panic("%s: lock (%s) %s not locked", __func__, 1861 lock->lo_class->lc_name, lock->lo_name); 1862 lock->lo_witness->w_file = file; 1863 lock->lo_witness->w_line = line; 1864 instance->li_file = file; 1865 instance->li_line = line; 1866 } 1867 1868 void 1869 witness_assert(struct lock_object *lock, int flags, const char *file, int line) 1870 { 1871 #ifdef INVARIANT_SUPPORT 1872 struct lock_instance *instance; 1873 1874 if (lock->lo_witness == NULL || witness_watch == 0 || panicstr != NULL) 1875 return; 1876 if ((lock->lo_class->lc_flags & LC_SLEEPLOCK) != 0) 1877 instance = find_instance(curthread->td_sleeplocks, lock); 1878 else if ((lock->lo_class->lc_flags & LC_SPINLOCK) != 0) 1879 instance = find_instance(PCPU_GET(spinlocks), lock); 1880 else { 1881 panic("Lock (%s) %s is not sleep or spin!", 1882 lock->lo_class->lc_name, lock->lo_name); 1883 } 1884 file = fixup_filename(file); 1885 switch (flags) { 1886 case LA_UNLOCKED: 1887 if (instance != NULL) 1888 panic("Lock (%s) %s locked @ %s:%d.", 1889 lock->lo_class->lc_name, lock->lo_name, file, line); 1890 break; 1891 case LA_LOCKED: 1892 case LA_LOCKED | LA_RECURSED: 1893 case LA_LOCKED | LA_NOTRECURSED: 1894 case LA_SLOCKED: 1895 case LA_SLOCKED | LA_RECURSED: 1896 case LA_SLOCKED | LA_NOTRECURSED: 1897 case LA_XLOCKED: 1898 case LA_XLOCKED | LA_RECURSED: 1899 case LA_XLOCKED | LA_NOTRECURSED: 1900 if (instance == NULL) { 1901 panic("Lock (%s) %s not locked @ %s:%d.", 1902 lock->lo_class->lc_name, lock->lo_name, file, line); 1903 break; 1904 } 1905 if ((flags & LA_XLOCKED) != 0 && 1906 (instance->li_flags & LI_EXCLUSIVE) == 0) 1907 panic("Lock (%s) %s not exclusively locked @ %s:%d.", 1908 lock->lo_class->lc_name, lock->lo_name, file, line); 1909 if ((flags & LA_SLOCKED) != 0 && 1910 (instance->li_flags & LI_EXCLUSIVE) != 0) 1911 panic("Lock (%s) %s exclusively locked @ %s:%d.", 1912 lock->lo_class->lc_name, lock->lo_name, file, line); 1913 if ((flags & LA_RECURSED) != 0 && 1914 (instance->li_flags & LI_RECURSEMASK) == 0) 1915 panic("Lock (%s) %s not recursed @ %s:%d.", 1916 lock->lo_class->lc_name, lock->lo_name, file, line); 1917 if ((flags & LA_NOTRECURSED) != 0 && 1918 (instance->li_flags & LI_RECURSEMASK) != 0) 1919 panic("Lock (%s) %s recursed @ %s:%d.", 1920 lock->lo_class->lc_name, lock->lo_name, file, line); 1921 break; 1922 default: 1923 panic("Invalid lock assertion at %s:%d.", file, line); 1924 1925 } 1926 #endif /* INVARIANT_SUPPORT */ 1927 } 1928 1929 #ifdef DDB 1930 static void 1931 witness_list(struct thread *td) 1932 { 1933 1934 KASSERT(!witness_cold, ("%s: witness_cold", __func__)); 1935 KASSERT(kdb_active, ("%s: not in the debugger", __func__)); 1936 1937 if (witness_watch == 0) 1938 return; 1939 1940 witness_list_locks(&td->td_sleeplocks); 1941 1942 /* 1943 * We only handle spinlocks if td == curthread. This is somewhat broken 1944 * if td is currently executing on some other CPU and holds spin locks 1945 * as we won't display those locks. If we had a MI way of getting 1946 * the per-cpu data for a given cpu then we could use 1947 * td->td_oncpu to get the list of spinlocks for this thread 1948 * and "fix" this. 1949 * 1950 * That still wouldn't really fix this unless we locked sched_lock 1951 * or stopped the other CPU to make sure it wasn't changing the list 1952 * out from under us. It is probably best to just not try to handle 1953 * threads on other CPU's for now. 1954 */ 1955 if (td == curthread && PCPU_GET(spinlocks) != NULL) 1956 witness_list_locks(PCPU_PTR(spinlocks)); 1957 } 1958 1959 DB_SHOW_COMMAND(locks, db_witness_list) 1960 { 1961 struct thread *td; 1962 pid_t pid; 1963 struct proc *p; 1964 1965 if (have_addr) { 1966 pid = (addr % 16) + ((addr >> 4) % 16) * 10 + 1967 ((addr >> 8) % 16) * 100 + ((addr >> 12) % 16) * 1000 + 1968 ((addr >> 16) % 16) * 10000; 1969 /* sx_slock(&allproc_lock); */ 1970 FOREACH_PROC_IN_SYSTEM(p) { 1971 if (p->p_pid == pid) 1972 break; 1973 } 1974 /* sx_sunlock(&allproc_lock); */ 1975 if (p == NULL) { 1976 db_printf("pid %d not found\n", pid); 1977 return; 1978 } 1979 FOREACH_THREAD_IN_PROC(p, td) { 1980 witness_list(td); 1981 } 1982 } else { 1983 td = curthread; 1984 witness_list(td); 1985 } 1986 } 1987 1988 DB_SHOW_COMMAND(alllocks, db_witness_list_all) 1989 { 1990 struct thread *td; 1991 struct proc *p; 1992 1993 /* 1994 * It would be nice to list only threads and processes that actually 1995 * held sleep locks, but that information is currently not exported 1996 * by WITNESS. 1997 */ 1998 FOREACH_PROC_IN_SYSTEM(p) { 1999 if (!witness_proc_has_locks(p)) 2000 continue; 2001 FOREACH_THREAD_IN_PROC(p, td) { 2002 if (!witness_thread_has_locks(td)) 2003 continue; 2004 printf("Process %d (%s) thread %p (%d)\n", p->p_pid, 2005 p->p_comm, td, td->td_tid); 2006 witness_list(td); 2007 } 2008 } 2009 } 2010 2011 DB_SHOW_COMMAND(witness, db_witness_display) 2012 { 2013 2014 witness_display(db_printf); 2015 } 2016 #endif
Cache object: 0807e224bdc9a44589cdb01929694c4f
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