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 /* Easier to stay with the old names. */ 107 #define lo_list lo_witness_data.lod_list 108 #define lo_witness lo_witness_data.lod_witness 109 110 /* Define this to check for blessed mutexes */ 111 #undef BLESSING 112 113 #define WITNESS_COUNT 1024 114 #define WITNESS_CHILDCOUNT (WITNESS_COUNT * 4) 115 /* 116 * XXX: This is somewhat bogus, as we assume here that at most 1024 threads 117 * will hold LOCK_NCHILDREN * 2 locks. We handle failure ok, and we should 118 * probably be safe for the most part, but it's still a SWAG. 119 */ 120 #define LOCK_CHILDCOUNT (MAXCPU + 1024) * 2 121 122 #define WITNESS_NCHILDREN 6 123 124 struct witness_child_list_entry; 125 126 struct witness { 127 const char *w_name; 128 struct lock_class *w_class; 129 STAILQ_ENTRY(witness) w_list; /* List of all witnesses. */ 130 STAILQ_ENTRY(witness) w_typelist; /* Witnesses of a type. */ 131 struct witness_child_list_entry *w_children; /* Great evilness... */ 132 const char *w_file; 133 int w_line; 134 u_int w_level; 135 u_int w_refcount; 136 u_char w_Giant_squawked:1; 137 u_char w_other_squawked:1; 138 u_char w_same_squawked:1; 139 u_char w_displayed:1; 140 }; 141 142 struct witness_child_list_entry { 143 struct witness_child_list_entry *wcl_next; 144 struct witness *wcl_children[WITNESS_NCHILDREN]; 145 u_int wcl_count; 146 }; 147 148 STAILQ_HEAD(witness_list, witness); 149 150 #ifdef BLESSING 151 struct witness_blessed { 152 const char *b_lock1; 153 const char *b_lock2; 154 }; 155 #endif 156 157 struct witness_order_list_entry { 158 const char *w_name; 159 struct lock_class *w_class; 160 }; 161 162 #ifdef BLESSING 163 static int blessed(struct witness *, struct witness *); 164 #endif 165 static int depart(struct witness *w); 166 static struct witness *enroll(const char *description, 167 struct lock_class *lock_class); 168 static int insertchild(struct witness *parent, struct witness *child); 169 static int isitmychild(struct witness *parent, struct witness *child); 170 static int isitmydescendant(struct witness *parent, struct witness *child); 171 static int itismychild(struct witness *parent, struct witness *child); 172 static void removechild(struct witness *parent, struct witness *child); 173 static int sysctl_debug_witness_watch(SYSCTL_HANDLER_ARGS); 174 static const char *fixup_filename(const char *file); 175 static struct witness *witness_get(void); 176 static void witness_free(struct witness *m); 177 static struct witness_child_list_entry *witness_child_get(void); 178 static void witness_child_free(struct witness_child_list_entry *wcl); 179 static struct lock_list_entry *witness_lock_list_get(void); 180 static void witness_lock_list_free(struct lock_list_entry *lle); 181 static struct lock_instance *find_instance(struct lock_list_entry *lock_list, 182 struct lock_object *lock); 183 static void witness_list_lock(struct lock_instance *instance); 184 #ifdef DDB 185 static void witness_leveldescendents(struct witness *parent, int level); 186 static void witness_levelall(void); 187 static void witness_displaydescendants(void(*)(const char *fmt, ...), 188 struct witness *, int indent); 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 static void witness_list(struct thread *td); 193 #endif 194 195 SYSCTL_NODE(_debug, OID_AUTO, witness, CTLFLAG_RW, 0, "Witness Locking"); 196 197 /* 198 * If set to 0, witness is disabled. If set to a non-zero value, witness 199 * performs full lock order checking for all locks. At runtime, this 200 * value may be set to 0 to turn off witness. witness is not allowed be 201 * turned on once it is turned off, however. 202 */ 203 static int witness_watch = 1; 204 TUNABLE_INT("debug.witness.watch", &witness_watch); 205 SYSCTL_PROC(_debug_witness, OID_AUTO, watch, CTLFLAG_RW | CTLTYPE_INT, NULL, 0, 206 sysctl_debug_witness_watch, "I", "witness is watching lock operations"); 207 208 #ifdef KDB 209 /* 210 * When KDB is enabled and witness_kdb is set to 1, it will cause the system 211 * to drop into kdebug() when: 212 * - a lock hierarchy violation occurs 213 * - locks are held when going to sleep. 214 */ 215 #ifdef WITNESS_KDB 216 int witness_kdb = 1; 217 #else 218 int witness_kdb = 0; 219 #endif 220 TUNABLE_INT("debug.witness.kdb", &witness_kdb); 221 SYSCTL_INT(_debug_witness, OID_AUTO, kdb, CTLFLAG_RW, &witness_kdb, 0, ""); 222 223 /* 224 * When KDB is enabled and witness_trace is set to 1, it will cause the system 225 * to print a stack trace: 226 * - a lock hierarchy violation occurs 227 * - locks are held when going to sleep. 228 */ 229 int witness_trace = 1; 230 TUNABLE_INT("debug.witness.trace", &witness_trace); 231 SYSCTL_INT(_debug_witness, OID_AUTO, trace, CTLFLAG_RW, &witness_trace, 0, ""); 232 #endif /* KDB */ 233 234 #ifdef WITNESS_SKIPSPIN 235 int witness_skipspin = 1; 236 #else 237 int witness_skipspin = 0; 238 #endif 239 TUNABLE_INT("debug.witness.skipspin", &witness_skipspin); 240 SYSCTL_INT(_debug_witness, OID_AUTO, skipspin, CTLFLAG_RDTUN, 241 &witness_skipspin, 0, ""); 242 243 static struct mtx w_mtx; 244 static struct witness_list w_free = STAILQ_HEAD_INITIALIZER(w_free); 245 static struct witness_list w_all = STAILQ_HEAD_INITIALIZER(w_all); 246 static struct witness_list w_spin = STAILQ_HEAD_INITIALIZER(w_spin); 247 static struct witness_list w_sleep = STAILQ_HEAD_INITIALIZER(w_sleep); 248 static struct witness_child_list_entry *w_child_free = NULL; 249 static struct lock_list_entry *w_lock_list_free = NULL; 250 251 static int w_free_cnt, w_spin_cnt, w_sleep_cnt, w_child_free_cnt, w_child_cnt; 252 SYSCTL_INT(_debug_witness, OID_AUTO, free_cnt, CTLFLAG_RD, &w_free_cnt, 0, ""); 253 SYSCTL_INT(_debug_witness, OID_AUTO, spin_cnt, CTLFLAG_RD, &w_spin_cnt, 0, ""); 254 SYSCTL_INT(_debug_witness, OID_AUTO, sleep_cnt, CTLFLAG_RD, &w_sleep_cnt, 0, 255 ""); 256 SYSCTL_INT(_debug_witness, OID_AUTO, child_free_cnt, CTLFLAG_RD, 257 &w_child_free_cnt, 0, ""); 258 SYSCTL_INT(_debug_witness, OID_AUTO, child_cnt, CTLFLAG_RD, &w_child_cnt, 0, 259 ""); 260 261 static struct witness w_data[WITNESS_COUNT]; 262 static struct witness_child_list_entry w_childdata[WITNESS_CHILDCOUNT]; 263 static struct lock_list_entry w_locklistdata[LOCK_CHILDCOUNT]; 264 265 static struct witness_order_list_entry order_lists[] = { 266 /* 267 * sx locks 268 */ 269 { "proctree", &lock_class_sx }, 270 { "allproc", &lock_class_sx }, 271 { NULL, NULL }, 272 /* 273 * Various mutexes 274 */ 275 { "Giant", &lock_class_mtx_sleep }, 276 { "filedesc structure", &lock_class_mtx_sleep }, 277 { "pipe mutex", &lock_class_mtx_sleep }, 278 { "sigio lock", &lock_class_mtx_sleep }, 279 { "process group", &lock_class_mtx_sleep }, 280 { "process lock", &lock_class_mtx_sleep }, 281 { "session", &lock_class_mtx_sleep }, 282 { "uidinfo hash", &lock_class_mtx_sleep }, 283 { "uidinfo struct", &lock_class_mtx_sleep }, 284 { "allprison", &lock_class_mtx_sleep }, 285 { NULL, NULL }, 286 /* 287 * Sockets 288 */ 289 { "filedesc structure", &lock_class_mtx_sleep }, 290 { "accept", &lock_class_mtx_sleep }, 291 { "so_snd", &lock_class_mtx_sleep }, 292 { "so_rcv", &lock_class_mtx_sleep }, 293 { "sellck", &lock_class_mtx_sleep }, 294 { NULL, NULL }, 295 /* 296 * Routing 297 */ 298 { "so_rcv", &lock_class_mtx_sleep }, 299 { "radix node head", &lock_class_mtx_sleep }, 300 { "rtentry", &lock_class_mtx_sleep }, 301 { "ifaddr", &lock_class_mtx_sleep }, 302 { NULL, NULL }, 303 /* 304 * Multicast - protocol locks before interface locks, after UDP locks. 305 */ 306 { "udpinp", &lock_class_mtx_sleep }, 307 { "in_multi_mtx", &lock_class_mtx_sleep }, 308 { "igmp_mtx", &lock_class_mtx_sleep }, 309 { "if_addr_mtx", &lock_class_mtx_sleep }, 310 { NULL, NULL }, 311 /* 312 * UNIX Domain Sockets 313 */ 314 { "unp", &lock_class_mtx_sleep }, 315 { "so_snd", &lock_class_mtx_sleep }, 316 { NULL, NULL }, 317 /* 318 * UDP/IP 319 */ 320 { "udp", &lock_class_mtx_sleep }, 321 { "udpinp", &lock_class_mtx_sleep }, 322 { "so_snd", &lock_class_mtx_sleep }, 323 { NULL, NULL }, 324 /* 325 * TCP/IP 326 */ 327 { "tcp", &lock_class_mtx_sleep }, 328 { "tcpinp", &lock_class_mtx_sleep }, 329 { "so_snd", &lock_class_mtx_sleep }, 330 { NULL, NULL }, 331 /* 332 * SLIP 333 */ 334 { "slip_mtx", &lock_class_mtx_sleep }, 335 { "slip sc_mtx", &lock_class_mtx_sleep }, 336 { NULL, NULL }, 337 /* 338 * netatalk 339 */ 340 { "ddp_list_mtx", &lock_class_mtx_sleep }, 341 { "ddp_mtx", &lock_class_mtx_sleep }, 342 { NULL, NULL }, 343 /* 344 * BPF 345 */ 346 { "bpf global lock", &lock_class_mtx_sleep }, 347 { "bpf interface lock", &lock_class_mtx_sleep }, 348 { "bpf cdev lock", &lock_class_mtx_sleep }, 349 { NULL, NULL }, 350 /* 351 * NFS server 352 */ 353 { "nfsd_mtx", &lock_class_mtx_sleep }, 354 { "so_snd", &lock_class_mtx_sleep }, 355 { NULL, NULL }, 356 /* 357 * CDEV 358 */ 359 { "system map", &lock_class_mtx_sleep }, 360 { "vm page queue mutex", &lock_class_mtx_sleep }, 361 { "vnode interlock", &lock_class_mtx_sleep }, 362 { "cdev", &lock_class_mtx_sleep }, 363 { NULL, NULL }, 364 /* 365 * spin locks 366 */ 367 #ifdef SMP 368 { "ap boot", &lock_class_mtx_spin }, 369 #endif 370 { "rm.mutex_mtx", &lock_class_mtx_spin }, 371 { "hptlock", &lock_class_mtx_spin }, 372 { "sio", &lock_class_mtx_spin }, 373 #ifdef __i386__ 374 { "cy", &lock_class_mtx_spin }, 375 #endif 376 { "uart_hwmtx", &lock_class_mtx_spin }, 377 { "sabtty", &lock_class_mtx_spin }, 378 { "zstty", &lock_class_mtx_spin }, 379 { "ng_node", &lock_class_mtx_spin }, 380 { "ng_worklist", &lock_class_mtx_spin }, 381 { "taskqueue_fast", &lock_class_mtx_spin }, 382 { "intr table", &lock_class_mtx_spin }, 383 { "sleepq chain", &lock_class_mtx_spin }, 384 { "sched lock", &lock_class_mtx_spin }, 385 { "turnstile chain", &lock_class_mtx_spin }, 386 { "td_contested", &lock_class_mtx_spin }, 387 { "callout", &lock_class_mtx_spin }, 388 { "entropy harvest mutex", &lock_class_mtx_spin }, 389 /* 390 * leaf locks 391 */ 392 { "allpmaps", &lock_class_mtx_spin }, 393 { "vm page queue free mutex", &lock_class_mtx_spin }, 394 { "icu", &lock_class_mtx_spin }, 395 #ifdef SMP 396 { "smp rendezvous", &lock_class_mtx_spin }, 397 #if defined(__i386__) || defined(__amd64__) 398 { "tlb", &lock_class_mtx_spin }, 399 #endif 400 #ifdef __sparc64__ 401 { "ipi", &lock_class_mtx_spin }, 402 { "rtc_mtx", &lock_class_mtx_spin }, 403 #endif 404 #endif 405 { "clk", &lock_class_mtx_spin }, 406 { "mutex profiling lock", &lock_class_mtx_spin }, 407 { "kse zombie lock", &lock_class_mtx_spin }, 408 { "ALD Queue", &lock_class_mtx_spin }, 409 #ifdef __ia64__ 410 { "MCA spin lock", &lock_class_mtx_spin }, 411 #endif 412 #if defined(__i386__) || defined(__amd64__) 413 { "pcicfg", &lock_class_mtx_spin }, 414 { "NDIS thread lock", &lock_class_mtx_spin }, 415 #endif 416 { "tw_osl_io_lock", &lock_class_mtx_spin }, 417 { "tw_osl_q_lock", &lock_class_mtx_spin }, 418 { "tw_cl_io_lock", &lock_class_mtx_spin }, 419 { "tw_cl_intr_lock", &lock_class_mtx_spin }, 420 { "tw_cl_gen_lock", &lock_class_mtx_spin }, 421 { NULL, NULL }, 422 { NULL, NULL } 423 }; 424 425 #ifdef BLESSING 426 /* 427 * Pairs of locks which have been blessed 428 * Don't complain about order problems with blessed locks 429 */ 430 static struct witness_blessed blessed_list[] = { 431 }; 432 static int blessed_count = 433 sizeof(blessed_list) / sizeof(struct witness_blessed); 434 #endif 435 436 /* 437 * List of locks initialized prior to witness being initialized whose 438 * enrollment is currently deferred. 439 */ 440 STAILQ_HEAD(, lock_object) pending_locks = 441 STAILQ_HEAD_INITIALIZER(pending_locks); 442 443 /* 444 * This global is set to 0 once it becomes safe to use the witness code. 445 */ 446 static int witness_cold = 1; 447 448 /* 449 * This global is set to 1 once the static lock orders have been enrolled 450 * so that a warning can be issued for any spin locks enrolled later. 451 */ 452 static int witness_spin_warn = 0; 453 454 /* 455 * The WITNESS-enabled diagnostic code. Note that the witness code does 456 * assume that the early boot is single-threaded at least until after this 457 * routine is completed. 458 */ 459 static void 460 witness_initialize(void *dummy __unused) 461 { 462 struct lock_object *lock; 463 struct witness_order_list_entry *order; 464 struct witness *w, *w1; 465 int i; 466 467 /* 468 * We have to release Giant before initializing its witness 469 * structure so that WITNESS doesn't get confused. 470 */ 471 mtx_unlock(&Giant); 472 mtx_assert(&Giant, MA_NOTOWNED); 473 474 CTR1(KTR_WITNESS, "%s: initializing witness", __func__); 475 mtx_init(&w_mtx, "witness lock", NULL, MTX_SPIN | MTX_QUIET | 476 MTX_NOWITNESS); 477 for (i = 0; i < WITNESS_COUNT; i++) 478 witness_free(&w_data[i]); 479 for (i = 0; i < WITNESS_CHILDCOUNT; i++) 480 witness_child_free(&w_childdata[i]); 481 for (i = 0; i < LOCK_CHILDCOUNT; i++) 482 witness_lock_list_free(&w_locklistdata[i]); 483 484 /* First add in all the specified order lists. */ 485 for (order = order_lists; order->w_name != NULL; order++) { 486 w = enroll(order->w_name, order->w_class); 487 if (w == NULL) 488 continue; 489 w->w_file = "order list"; 490 for (order++; order->w_name != NULL; order++) { 491 w1 = enroll(order->w_name, order->w_class); 492 if (w1 == NULL) 493 continue; 494 w1->w_file = "order list"; 495 if (!itismychild(w, w1)) 496 panic("Not enough memory for static orders!"); 497 w = w1; 498 } 499 } 500 witness_spin_warn = 1; 501 502 /* Iterate through all locks and add them to witness. */ 503 while (!STAILQ_EMPTY(&pending_locks)) { 504 lock = STAILQ_FIRST(&pending_locks); 505 STAILQ_REMOVE_HEAD(&pending_locks, lo_list); 506 KASSERT(lock->lo_flags & LO_WITNESS, 507 ("%s: lock %s is on pending list but not LO_WITNESS", 508 __func__, lock->lo_name)); 509 lock->lo_witness = enroll(lock->lo_type, lock->lo_class); 510 } 511 512 /* Mark the witness code as being ready for use. */ 513 witness_cold = 0; 514 515 mtx_lock(&Giant); 516 } 517 SYSINIT(witness_init, SI_SUB_WITNESS, SI_ORDER_FIRST, witness_initialize, NULL) 518 519 static int 520 sysctl_debug_witness_watch(SYSCTL_HANDLER_ARGS) 521 { 522 int error, value; 523 524 value = witness_watch; 525 error = sysctl_handle_int(oidp, &value, 0, req); 526 if (error != 0 || req->newptr == NULL) 527 return (error); 528 error = suser(req->td); 529 if (error != 0) 530 return (error); 531 if (value == witness_watch) 532 return (0); 533 if (value != 0) 534 return (EINVAL); 535 witness_watch = 0; 536 return (0); 537 } 538 539 void 540 witness_init(struct lock_object *lock) 541 { 542 struct lock_class *class; 543 544 /* Various sanity checks. */ 545 class = lock->lo_class; 546 if (lock->lo_flags & LO_INITIALIZED) 547 panic("%s: lock (%s) %s is already initialized", __func__, 548 class->lc_name, lock->lo_name); 549 if ((lock->lo_flags & LO_RECURSABLE) != 0 && 550 (class->lc_flags & LC_RECURSABLE) == 0) 551 panic("%s: lock (%s) %s can not be recursable", __func__, 552 class->lc_name, lock->lo_name); 553 if ((lock->lo_flags & LO_SLEEPABLE) != 0 && 554 (class->lc_flags & LC_SLEEPABLE) == 0) 555 panic("%s: lock (%s) %s can not be sleepable", __func__, 556 class->lc_name, lock->lo_name); 557 if ((lock->lo_flags & LO_UPGRADABLE) != 0 && 558 (class->lc_flags & LC_UPGRADABLE) == 0) 559 panic("%s: lock (%s) %s can not be upgradable", __func__, 560 class->lc_name, lock->lo_name); 561 562 /* 563 * If we shouldn't watch this lock, then just clear lo_witness. 564 * Otherwise, if witness_cold is set, then it is too early to 565 * enroll this lock, so defer it to witness_initialize() by adding 566 * it to the pending_locks list. If it is not too early, then enroll 567 * the lock now. 568 */ 569 lock->lo_flags |= LO_INITIALIZED; 570 if (witness_watch == 0 || panicstr != NULL || 571 (lock->lo_flags & LO_WITNESS) == 0) 572 lock->lo_witness = NULL; 573 else if (witness_cold) { 574 STAILQ_INSERT_TAIL(&pending_locks, lock, lo_list); 575 lock->lo_flags |= LO_ENROLLPEND; 576 } else 577 lock->lo_witness = enroll(lock->lo_type, class); 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 if ((lock->lo_flags & (LO_WITNESS | LO_ENROLLPEND)) == LO_WITNESS && 594 lock->lo_witness != NULL) { 595 w = lock->lo_witness; 596 mtx_lock_spin(&w_mtx); 597 MPASS(w->w_refcount > 0); 598 w->w_refcount--; 599 600 /* 601 * Lock is already released if we have an allocation failure 602 * and depart() fails. 603 */ 604 if (w->w_refcount != 0 || depart(w)) 605 mtx_unlock_spin(&w_mtx); 606 } 607 608 /* 609 * If this lock is destroyed before witness is up and running, 610 * remove it from the pending list. 611 */ 612 if (lock->lo_flags & LO_ENROLLPEND) { 613 STAILQ_REMOVE(&pending_locks, lock, lock_object, lo_list); 614 lock->lo_flags &= ~LO_ENROLLPEND; 615 } 616 lock->lo_flags &= ~LO_INITIALIZED; 617 } 618 619 #ifdef DDB 620 static void 621 witness_levelall (void) 622 { 623 struct witness_list *list; 624 struct witness *w, *w1; 625 626 /* 627 * First clear all levels. 628 */ 629 STAILQ_FOREACH(w, &w_all, w_list) { 630 w->w_level = 0; 631 } 632 633 /* 634 * Look for locks with no parent and level all their descendants. 635 */ 636 STAILQ_FOREACH(w, &w_all, w_list) { 637 /* 638 * This is just an optimization, technically we could get 639 * away just walking the all list each time. 640 */ 641 if (w->w_class->lc_flags & LC_SLEEPLOCK) 642 list = &w_sleep; 643 else 644 list = &w_spin; 645 STAILQ_FOREACH(w1, list, w_typelist) { 646 if (isitmychild(w1, w)) 647 goto skip; 648 } 649 witness_leveldescendents(w, 0); 650 skip: 651 ; /* silence GCC 3.x */ 652 } 653 } 654 655 static void 656 witness_leveldescendents(struct witness *parent, int level) 657 { 658 struct witness_child_list_entry *wcl; 659 int i; 660 661 if (parent->w_level < level) 662 parent->w_level = level; 663 level++; 664 for (wcl = parent->w_children; wcl != NULL; wcl = wcl->wcl_next) 665 for (i = 0; i < wcl->wcl_count; i++) 666 witness_leveldescendents(wcl->wcl_children[i], level); 667 } 668 669 static void 670 witness_displaydescendants(void(*prnt)(const char *fmt, ...), 671 struct witness *parent, int indent) 672 { 673 struct witness_child_list_entry *wcl; 674 int i, level; 675 676 level = parent->w_level; 677 prnt("%-2d", level); 678 for (i = 0; i < indent; i++) 679 prnt(" "); 680 if (parent->w_refcount > 0) 681 prnt("%s", parent->w_name); 682 else 683 prnt("(dead)"); 684 if (parent->w_displayed) { 685 prnt(" -- (already displayed)\n"); 686 return; 687 } 688 parent->w_displayed = 1; 689 if (parent->w_refcount > 0) { 690 if (parent->w_file != NULL) 691 prnt(" -- last acquired @ %s:%d", parent->w_file, 692 parent->w_line); 693 } 694 prnt("\n"); 695 for (wcl = parent->w_children; wcl != NULL; wcl = wcl->wcl_next) 696 for (i = 0; i < wcl->wcl_count; i++) 697 witness_displaydescendants(prnt, 698 wcl->wcl_children[i], indent + 1); 699 } 700 701 static void 702 witness_display_list(void(*prnt)(const char *fmt, ...), 703 struct witness_list *list) 704 { 705 struct witness *w; 706 707 STAILQ_FOREACH(w, list, w_typelist) { 708 if (w->w_file == NULL || w->w_level > 0) 709 continue; 710 /* 711 * This lock has no anscestors, display its descendants. 712 */ 713 witness_displaydescendants(prnt, w, 0); 714 } 715 } 716 717 static void 718 witness_display(void(*prnt)(const char *fmt, ...)) 719 { 720 struct witness *w; 721 722 KASSERT(!witness_cold, ("%s: witness_cold", __func__)); 723 witness_levelall(); 724 725 /* Clear all the displayed flags. */ 726 STAILQ_FOREACH(w, &w_all, w_list) { 727 w->w_displayed = 0; 728 } 729 730 /* 731 * First, handle sleep locks which have been acquired at least 732 * once. 733 */ 734 prnt("Sleep locks:\n"); 735 witness_display_list(prnt, &w_sleep); 736 737 /* 738 * Now do spin locks which have been acquired at least once. 739 */ 740 prnt("\nSpin locks:\n"); 741 witness_display_list(prnt, &w_spin); 742 743 /* 744 * Finally, any locks which have not been acquired yet. 745 */ 746 prnt("\nLocks which were never acquired:\n"); 747 STAILQ_FOREACH(w, &w_all, w_list) { 748 if (w->w_file != NULL || w->w_refcount == 0) 749 continue; 750 prnt("%s\n", w->w_name); 751 } 752 } 753 #endif /* DDB */ 754 755 /* Trim useless garbage from filenames. */ 756 static const char * 757 fixup_filename(const char *file) 758 { 759 760 if (file == NULL) 761 return (NULL); 762 while (strncmp(file, "../", 3) == 0) 763 file += 3; 764 return (file); 765 } 766 767 int 768 witness_defineorder(struct lock_object *lock1, struct lock_object *lock2) 769 { 770 771 if (witness_watch == 0 || panicstr != NULL) 772 return (0); 773 774 /* Require locks that witness knows about. */ 775 if (lock1 == NULL || lock1->lo_witness == NULL || lock2 == NULL || 776 lock2->lo_witness == NULL) 777 return (EINVAL); 778 779 MPASS(!mtx_owned(&w_mtx)); 780 mtx_lock_spin(&w_mtx); 781 782 /* 783 * If we already have either an explicit or implied lock order that 784 * is the other way around, then return an error. 785 */ 786 if (isitmydescendant(lock2->lo_witness, lock1->lo_witness)) { 787 mtx_unlock_spin(&w_mtx); 788 return (EDOOFUS); 789 } 790 791 /* Try to add the new order. */ 792 CTR3(KTR_WITNESS, "%s: adding %s as a child of %s", __func__, 793 lock2->lo_type, lock1->lo_type); 794 if (!itismychild(lock1->lo_witness, lock2->lo_witness)) 795 return (ENOMEM); 796 mtx_unlock_spin(&w_mtx); 797 return (0); 798 } 799 800 void 801 witness_checkorder(struct lock_object *lock, int flags, const char *file, 802 int line) 803 { 804 struct lock_list_entry **lock_list, *lle; 805 struct lock_instance *lock1, *lock2; 806 struct lock_class *class; 807 struct witness *w, *w1; 808 struct thread *td; 809 int i, j; 810 811 if (witness_cold || witness_watch == 0 || lock->lo_witness == NULL || 812 panicstr != NULL) 813 return; 814 815 /* 816 * Try locks do not block if they fail to acquire the lock, thus 817 * there is no danger of deadlocks or of switching while holding a 818 * spin lock if we acquire a lock via a try operation. This 819 * function shouldn't even be called for try locks, so panic if 820 * that happens. 821 */ 822 if (flags & LOP_TRYLOCK) 823 panic("%s should not be called for try lock operations", 824 __func__); 825 826 w = lock->lo_witness; 827 class = lock->lo_class; 828 td = curthread; 829 file = fixup_filename(file); 830 831 if (class->lc_flags & LC_SLEEPLOCK) { 832 /* 833 * Since spin locks include a critical section, this check 834 * implicitly enforces a lock order of all sleep locks before 835 * all spin locks. 836 */ 837 if (td->td_critnest != 0 && !kdb_active) 838 panic("blockable sleep lock (%s) %s @ %s:%d", 839 class->lc_name, lock->lo_name, file, line); 840 841 /* 842 * If this is the first lock acquired then just return as 843 * no order checking is needed. 844 */ 845 if (td->td_sleeplocks == NULL) 846 return; 847 lock_list = &td->td_sleeplocks; 848 } else { 849 /* 850 * If this is the first lock, just return as no order 851 * checking is needed. We check this in both if clauses 852 * here as unifying the check would require us to use a 853 * critical section to ensure we don't migrate while doing 854 * the check. Note that if this is not the first lock, we 855 * are already in a critical section and are safe for the 856 * rest of the check. 857 */ 858 if (PCPU_GET(spinlocks) == NULL) 859 return; 860 lock_list = PCPU_PTR(spinlocks); 861 } 862 863 /* 864 * Check to see if we are recursing on a lock we already own. If 865 * so, make sure that we don't mismatch exclusive and shared lock 866 * acquires. 867 */ 868 lock1 = find_instance(*lock_list, lock); 869 if (lock1 != NULL) { 870 if ((lock1->li_flags & LI_EXCLUSIVE) != 0 && 871 (flags & LOP_EXCLUSIVE) == 0) { 872 printf("shared lock of (%s) %s @ %s:%d\n", 873 class->lc_name, lock->lo_name, file, line); 874 printf("while exclusively locked from %s:%d\n", 875 lock1->li_file, lock1->li_line); 876 panic("share->excl"); 877 } 878 if ((lock1->li_flags & LI_EXCLUSIVE) == 0 && 879 (flags & LOP_EXCLUSIVE) != 0) { 880 printf("exclusive lock of (%s) %s @ %s:%d\n", 881 class->lc_name, lock->lo_name, file, line); 882 printf("while share locked from %s:%d\n", 883 lock1->li_file, lock1->li_line); 884 panic("excl->share"); 885 } 886 return; 887 } 888 889 /* 890 * Try locks do not block if they fail to acquire the lock, thus 891 * there is no danger of deadlocks or of switching while holding a 892 * spin lock if we acquire a lock via a try operation. 893 */ 894 if (flags & LOP_TRYLOCK) 895 return; 896 897 /* 898 * Check for duplicate locks of the same type. Note that we only 899 * have to check for this on the last lock we just acquired. Any 900 * other cases will be caught as lock order violations. 901 */ 902 lock1 = &(*lock_list)->ll_children[(*lock_list)->ll_count - 1]; 903 w1 = lock1->li_lock->lo_witness; 904 if (w1 == w) { 905 if (w->w_same_squawked || (lock->lo_flags & LO_DUPOK) || 906 (flags & LOP_DUPOK)) 907 return; 908 w->w_same_squawked = 1; 909 printf("acquiring duplicate lock of same type: \"%s\"\n", 910 lock->lo_type); 911 printf(" 1st %s @ %s:%d\n", lock1->li_lock->lo_name, 912 lock1->li_file, lock1->li_line); 913 printf(" 2nd %s @ %s:%d\n", lock->lo_name, file, line); 914 #ifdef KDB 915 goto debugger; 916 #else 917 return; 918 #endif 919 } 920 MPASS(!mtx_owned(&w_mtx)); 921 mtx_lock_spin(&w_mtx); 922 /* 923 * If we know that the the lock we are acquiring comes after 924 * the lock we most recently acquired in the lock order tree, 925 * then there is no need for any further checks. 926 */ 927 if (isitmychild(w1, w)) { 928 mtx_unlock_spin(&w_mtx); 929 return; 930 } 931 for (j = 0, lle = *lock_list; lle != NULL; lle = lle->ll_next) { 932 for (i = lle->ll_count - 1; i >= 0; i--, j++) { 933 934 MPASS(j < WITNESS_COUNT); 935 lock1 = &lle->ll_children[i]; 936 w1 = lock1->li_lock->lo_witness; 937 938 /* 939 * If this lock doesn't undergo witness checking, 940 * then skip it. 941 */ 942 if (w1 == NULL) { 943 KASSERT((lock1->li_lock->lo_flags & LO_WITNESS) == 0, 944 ("lock missing witness structure")); 945 continue; 946 } 947 /* 948 * If we are locking Giant and this is a sleepable 949 * lock, then skip it. 950 */ 951 if ((lock1->li_lock->lo_flags & LO_SLEEPABLE) != 0 && 952 lock == &Giant.mtx_object) 953 continue; 954 /* 955 * If we are locking a sleepable lock and this lock 956 * is Giant, then skip it. 957 */ 958 if ((lock->lo_flags & LO_SLEEPABLE) != 0 && 959 lock1->li_lock == &Giant.mtx_object) 960 continue; 961 /* 962 * If we are locking a sleepable lock and this lock 963 * isn't sleepable, we want to treat it as a lock 964 * order violation to enfore a general lock order of 965 * sleepable locks before non-sleepable locks. 966 */ 967 if (((lock->lo_flags & LO_SLEEPABLE) != 0 && 968 (lock1->li_lock->lo_flags & LO_SLEEPABLE) == 0)) 969 goto reversal; 970 /* 971 * If we are locking Giant and this is a non-sleepable 972 * lock, then treat it as a reversal. 973 */ 974 if ((lock1->li_lock->lo_flags & LO_SLEEPABLE) == 0 && 975 lock == &Giant.mtx_object) 976 goto reversal; 977 /* 978 * Check the lock order hierarchy for a reveresal. 979 */ 980 if (!isitmydescendant(w, w1)) 981 continue; 982 reversal: 983 /* 984 * We have a lock order violation, check to see if it 985 * is allowed or has already been yelled about. 986 */ 987 mtx_unlock_spin(&w_mtx); 988 #ifdef BLESSING 989 /* 990 * If the lock order is blessed, just bail. We don't 991 * look for other lock order violations though, which 992 * may be a bug. 993 */ 994 if (blessed(w, w1)) 995 return; 996 #endif 997 if (lock1->li_lock == &Giant.mtx_object) { 998 if (w1->w_Giant_squawked) 999 return; 1000 else 1001 w1->w_Giant_squawked = 1; 1002 } else { 1003 if (w1->w_other_squawked) 1004 return; 1005 else 1006 w1->w_other_squawked = 1; 1007 } 1008 /* 1009 * Ok, yell about it. 1010 */ 1011 if (((lock->lo_flags & LO_SLEEPABLE) != 0 && 1012 (lock1->li_lock->lo_flags & LO_SLEEPABLE) == 0)) 1013 printf( 1014 "lock order reversal: (sleepable after non-sleepable)\n"); 1015 else if ((lock1->li_lock->lo_flags & LO_SLEEPABLE) == 0 1016 && lock == &Giant.mtx_object) 1017 printf( 1018 "lock order reversal: (Giant after non-sleepable)\n"); 1019 else 1020 printf("lock order reversal:\n"); 1021 /* 1022 * Try to locate an earlier lock with 1023 * witness w in our list. 1024 */ 1025 do { 1026 lock2 = &lle->ll_children[i]; 1027 MPASS(lock2->li_lock != NULL); 1028 if (lock2->li_lock->lo_witness == w) 1029 break; 1030 if (i == 0 && lle->ll_next != NULL) { 1031 lle = lle->ll_next; 1032 i = lle->ll_count - 1; 1033 MPASS(i >= 0 && i < LOCK_NCHILDREN); 1034 } else 1035 i--; 1036 } while (i >= 0); 1037 if (i < 0) { 1038 printf(" 1st %p %s (%s) @ %s:%d\n", 1039 lock1->li_lock, lock1->li_lock->lo_name, 1040 lock1->li_lock->lo_type, lock1->li_file, 1041 lock1->li_line); 1042 printf(" 2nd %p %s (%s) @ %s:%d\n", lock, 1043 lock->lo_name, lock->lo_type, file, line); 1044 } else { 1045 printf(" 1st %p %s (%s) @ %s:%d\n", 1046 lock2->li_lock, lock2->li_lock->lo_name, 1047 lock2->li_lock->lo_type, lock2->li_file, 1048 lock2->li_line); 1049 printf(" 2nd %p %s (%s) @ %s:%d\n", 1050 lock1->li_lock, lock1->li_lock->lo_name, 1051 lock1->li_lock->lo_type, lock1->li_file, 1052 lock1->li_line); 1053 printf(" 3rd %p %s (%s) @ %s:%d\n", lock, 1054 lock->lo_name, lock->lo_type, file, line); 1055 } 1056 #ifdef KDB 1057 goto debugger; 1058 #else 1059 return; 1060 #endif 1061 } 1062 } 1063 lock1 = &(*lock_list)->ll_children[(*lock_list)->ll_count - 1]; 1064 /* 1065 * If requested, build a new lock order. However, don't build a new 1066 * relationship between a sleepable lock and Giant if it is in the 1067 * wrong direction. The correct lock order is that sleepable locks 1068 * always come before Giant. 1069 */ 1070 if (flags & LOP_NEWORDER && 1071 !(lock1->li_lock == &Giant.mtx_object && 1072 (lock->lo_flags & LO_SLEEPABLE) != 0)) { 1073 CTR3(KTR_WITNESS, "%s: adding %s as a child of %s", __func__, 1074 lock->lo_type, lock1->li_lock->lo_type); 1075 if (!itismychild(lock1->li_lock->lo_witness, w)) 1076 /* Witness is dead. */ 1077 return; 1078 } 1079 mtx_unlock_spin(&w_mtx); 1080 return; 1081 1082 #ifdef KDB 1083 debugger: 1084 if (witness_trace) 1085 kdb_backtrace(); 1086 if (witness_kdb) 1087 kdb_enter(__func__); 1088 #endif 1089 } 1090 1091 void 1092 witness_lock(struct lock_object *lock, int flags, const char *file, int line) 1093 { 1094 struct lock_list_entry **lock_list, *lle; 1095 struct lock_instance *instance; 1096 struct witness *w; 1097 struct thread *td; 1098 1099 if (witness_cold || witness_watch == 0 || lock->lo_witness == NULL || 1100 panicstr != NULL) 1101 return; 1102 w = lock->lo_witness; 1103 td = curthread; 1104 file = fixup_filename(file); 1105 1106 /* Determine lock list for this lock. */ 1107 if (lock->lo_class->lc_flags & LC_SLEEPLOCK) 1108 lock_list = &td->td_sleeplocks; 1109 else 1110 lock_list = PCPU_PTR(spinlocks); 1111 1112 /* Check to see if we are recursing on a lock we already own. */ 1113 instance = find_instance(*lock_list, lock); 1114 if (instance != NULL) { 1115 instance->li_flags++; 1116 CTR4(KTR_WITNESS, "%s: pid %d recursed on %s r=%d", __func__, 1117 td->td_proc->p_pid, lock->lo_name, 1118 instance->li_flags & LI_RECURSEMASK); 1119 instance->li_file = file; 1120 instance->li_line = line; 1121 return; 1122 } 1123 1124 /* Update per-witness last file and line acquire. */ 1125 w->w_file = file; 1126 w->w_line = line; 1127 1128 /* Find the next open lock instance in the list and fill it. */ 1129 lle = *lock_list; 1130 if (lle == NULL || lle->ll_count == LOCK_NCHILDREN) { 1131 lle = witness_lock_list_get(); 1132 if (lle == NULL) 1133 return; 1134 lle->ll_next = *lock_list; 1135 CTR3(KTR_WITNESS, "%s: pid %d added lle %p", __func__, 1136 td->td_proc->p_pid, lle); 1137 *lock_list = lle; 1138 } 1139 instance = &lle->ll_children[lle->ll_count++]; 1140 instance->li_lock = lock; 1141 instance->li_line = line; 1142 instance->li_file = file; 1143 if ((flags & LOP_EXCLUSIVE) != 0) 1144 instance->li_flags = LI_EXCLUSIVE; 1145 else 1146 instance->li_flags = 0; 1147 CTR4(KTR_WITNESS, "%s: pid %d added %s as lle[%d]", __func__, 1148 td->td_proc->p_pid, lock->lo_name, lle->ll_count - 1); 1149 } 1150 1151 void 1152 witness_upgrade(struct lock_object *lock, int flags, const char *file, int line) 1153 { 1154 struct lock_instance *instance; 1155 struct lock_class *class; 1156 1157 KASSERT(!witness_cold, ("%s: witness_cold", __func__)); 1158 if (lock->lo_witness == NULL || witness_watch == 0 || panicstr != NULL) 1159 return; 1160 class = lock->lo_class; 1161 file = fixup_filename(file); 1162 if ((lock->lo_flags & LO_UPGRADABLE) == 0) 1163 panic("upgrade of non-upgradable lock (%s) %s @ %s:%d", 1164 class->lc_name, lock->lo_name, file, line); 1165 if ((flags & LOP_TRYLOCK) == 0) 1166 panic("non-try upgrade of lock (%s) %s @ %s:%d", class->lc_name, 1167 lock->lo_name, file, line); 1168 if ((lock->lo_class->lc_flags & LC_SLEEPLOCK) == 0) 1169 panic("upgrade of non-sleep lock (%s) %s @ %s:%d", 1170 class->lc_name, lock->lo_name, file, line); 1171 instance = find_instance(curthread->td_sleeplocks, lock); 1172 if (instance == NULL) 1173 panic("upgrade of unlocked lock (%s) %s @ %s:%d", 1174 class->lc_name, lock->lo_name, file, line); 1175 if ((instance->li_flags & LI_EXCLUSIVE) != 0) 1176 panic("upgrade of exclusive lock (%s) %s @ %s:%d", 1177 class->lc_name, lock->lo_name, file, line); 1178 if ((instance->li_flags & LI_RECURSEMASK) != 0) 1179 panic("upgrade of recursed lock (%s) %s r=%d @ %s:%d", 1180 class->lc_name, lock->lo_name, 1181 instance->li_flags & LI_RECURSEMASK, file, line); 1182 instance->li_flags |= LI_EXCLUSIVE; 1183 } 1184 1185 void 1186 witness_downgrade(struct lock_object *lock, int flags, const char *file, 1187 int line) 1188 { 1189 struct lock_instance *instance; 1190 struct lock_class *class; 1191 1192 KASSERT(!witness_cold, ("%s: witness_cold", __func__)); 1193 if (lock->lo_witness == NULL || witness_watch == 0 || panicstr != NULL) 1194 return; 1195 class = lock->lo_class; 1196 file = fixup_filename(file); 1197 if ((lock->lo_flags & LO_UPGRADABLE) == 0) 1198 panic("downgrade of non-upgradable lock (%s) %s @ %s:%d", 1199 class->lc_name, lock->lo_name, file, line); 1200 if ((lock->lo_class->lc_flags & LC_SLEEPLOCK) == 0) 1201 panic("downgrade of non-sleep lock (%s) %s @ %s:%d", 1202 class->lc_name, lock->lo_name, file, line); 1203 instance = find_instance(curthread->td_sleeplocks, lock); 1204 if (instance == NULL) 1205 panic("downgrade of unlocked lock (%s) %s @ %s:%d", 1206 class->lc_name, lock->lo_name, file, line); 1207 if ((instance->li_flags & LI_EXCLUSIVE) == 0) 1208 panic("downgrade of shared lock (%s) %s @ %s:%d", 1209 class->lc_name, lock->lo_name, file, line); 1210 if ((instance->li_flags & LI_RECURSEMASK) != 0) 1211 panic("downgrade of recursed lock (%s) %s r=%d @ %s:%d", 1212 class->lc_name, lock->lo_name, 1213 instance->li_flags & LI_RECURSEMASK, file, line); 1214 instance->li_flags &= ~LI_EXCLUSIVE; 1215 } 1216 1217 void 1218 witness_unlock(struct lock_object *lock, int flags, const char *file, int line) 1219 { 1220 struct lock_list_entry **lock_list, *lle; 1221 struct lock_instance *instance; 1222 struct lock_class *class; 1223 struct thread *td; 1224 register_t s; 1225 int i, j; 1226 1227 if (witness_cold || witness_watch == 0 || lock->lo_witness == NULL || 1228 panicstr != NULL) 1229 return; 1230 td = curthread; 1231 class = lock->lo_class; 1232 file = fixup_filename(file); 1233 1234 /* Find lock instance associated with this lock. */ 1235 if (class->lc_flags & LC_SLEEPLOCK) 1236 lock_list = &td->td_sleeplocks; 1237 else 1238 lock_list = PCPU_PTR(spinlocks); 1239 for (; *lock_list != NULL; lock_list = &(*lock_list)->ll_next) 1240 for (i = 0; i < (*lock_list)->ll_count; i++) { 1241 instance = &(*lock_list)->ll_children[i]; 1242 if (instance->li_lock == lock) 1243 goto found; 1244 } 1245 panic("lock (%s) %s not locked @ %s:%d", class->lc_name, lock->lo_name, 1246 file, line); 1247 found: 1248 1249 /* First, check for shared/exclusive mismatches. */ 1250 if ((instance->li_flags & LI_EXCLUSIVE) != 0 && 1251 (flags & LOP_EXCLUSIVE) == 0) { 1252 printf("shared unlock of (%s) %s @ %s:%d\n", class->lc_name, 1253 lock->lo_name, file, line); 1254 printf("while exclusively locked from %s:%d\n", 1255 instance->li_file, instance->li_line); 1256 panic("excl->ushare"); 1257 } 1258 if ((instance->li_flags & LI_EXCLUSIVE) == 0 && 1259 (flags & LOP_EXCLUSIVE) != 0) { 1260 printf("exclusive unlock of (%s) %s @ %s:%d\n", class->lc_name, 1261 lock->lo_name, file, line); 1262 printf("while share locked from %s:%d\n", instance->li_file, 1263 instance->li_line); 1264 panic("share->uexcl"); 1265 } 1266 1267 /* If we are recursed, unrecurse. */ 1268 if ((instance->li_flags & LI_RECURSEMASK) > 0) { 1269 CTR4(KTR_WITNESS, "%s: pid %d unrecursed on %s r=%d", __func__, 1270 td->td_proc->p_pid, instance->li_lock->lo_name, 1271 instance->li_flags); 1272 instance->li_flags--; 1273 return; 1274 } 1275 1276 /* Otherwise, remove this item from the list. */ 1277 s = intr_disable(); 1278 CTR4(KTR_WITNESS, "%s: pid %d removed %s from lle[%d]", __func__, 1279 td->td_proc->p_pid, instance->li_lock->lo_name, 1280 (*lock_list)->ll_count - 1); 1281 for (j = i; j < (*lock_list)->ll_count - 1; j++) 1282 (*lock_list)->ll_children[j] = 1283 (*lock_list)->ll_children[j + 1]; 1284 (*lock_list)->ll_count--; 1285 intr_restore(s); 1286 1287 /* If this lock list entry is now empty, free it. */ 1288 if ((*lock_list)->ll_count == 0) { 1289 lle = *lock_list; 1290 *lock_list = lle->ll_next; 1291 CTR3(KTR_WITNESS, "%s: pid %d removed lle %p", __func__, 1292 td->td_proc->p_pid, lle); 1293 witness_lock_list_free(lle); 1294 } 1295 } 1296 1297 /* 1298 * Warn if any locks other than 'lock' are held. Flags can be passed in to 1299 * exempt Giant and sleepable locks from the checks as well. If any 1300 * non-exempt locks are held, then a supplied message is printed to the 1301 * console along with a list of the offending locks. If indicated in the 1302 * flags then a failure results in a panic as well. 1303 */ 1304 int 1305 witness_warn(int flags, struct lock_object *lock, const char *fmt, ...) 1306 { 1307 struct lock_list_entry *lle; 1308 struct lock_instance *lock1; 1309 struct thread *td; 1310 va_list ap; 1311 int i, n; 1312 1313 if (witness_cold || witness_watch == 0 || panicstr != NULL) 1314 return (0); 1315 n = 0; 1316 td = curthread; 1317 for (lle = td->td_sleeplocks; lle != NULL; lle = lle->ll_next) 1318 for (i = lle->ll_count - 1; i >= 0; i--) { 1319 lock1 = &lle->ll_children[i]; 1320 if (lock1->li_lock == lock) 1321 continue; 1322 if (flags & WARN_GIANTOK && 1323 lock1->li_lock == &Giant.mtx_object) 1324 continue; 1325 if (flags & WARN_SLEEPOK && 1326 (lock1->li_lock->lo_flags & LO_SLEEPABLE) != 0) 1327 continue; 1328 if (n == 0) { 1329 va_start(ap, fmt); 1330 vprintf(fmt, ap); 1331 va_end(ap); 1332 printf(" with the following"); 1333 if (flags & WARN_SLEEPOK) 1334 printf(" non-sleepable"); 1335 printf(" locks held:\n"); 1336 } 1337 n++; 1338 witness_list_lock(lock1); 1339 } 1340 if (PCPU_GET(spinlocks) != NULL) { 1341 /* 1342 * Since we already hold a spinlock preemption is 1343 * already blocked. 1344 */ 1345 if (n == 0) { 1346 va_start(ap, fmt); 1347 vprintf(fmt, ap); 1348 va_end(ap); 1349 printf(" with the following"); 1350 if (flags & WARN_SLEEPOK) 1351 printf(" non-sleepable"); 1352 printf(" locks held:\n"); 1353 } 1354 n += witness_list_locks(PCPU_PTR(spinlocks)); 1355 } 1356 if (flags & WARN_PANIC && n) 1357 panic("witness_warn"); 1358 #ifdef KDB 1359 else if (witness_kdb && n) 1360 kdb_enter(__func__); 1361 else if (witness_trace && n) 1362 kdb_backtrace(); 1363 #endif 1364 return (n); 1365 } 1366 1367 const char * 1368 witness_file(struct lock_object *lock) 1369 { 1370 struct witness *w; 1371 1372 if (witness_cold || witness_watch == 0 || lock->lo_witness == NULL) 1373 return ("?"); 1374 w = lock->lo_witness; 1375 return (w->w_file); 1376 } 1377 1378 int 1379 witness_line(struct lock_object *lock) 1380 { 1381 struct witness *w; 1382 1383 if (witness_cold || witness_watch == 0 || lock->lo_witness == NULL) 1384 return (0); 1385 w = lock->lo_witness; 1386 return (w->w_line); 1387 } 1388 1389 static struct witness * 1390 enroll(const char *description, struct lock_class *lock_class) 1391 { 1392 struct witness *w; 1393 1394 if (witness_watch == 0 || panicstr != NULL) 1395 return (NULL); 1396 if ((lock_class->lc_flags & LC_SPINLOCK) && witness_skipspin) 1397 return (NULL); 1398 mtx_lock_spin(&w_mtx); 1399 STAILQ_FOREACH(w, &w_all, w_list) { 1400 if (w->w_name == description || (w->w_refcount > 0 && 1401 strcmp(description, w->w_name) == 0)) { 1402 w->w_refcount++; 1403 mtx_unlock_spin(&w_mtx); 1404 if (lock_class != w->w_class) 1405 panic( 1406 "lock (%s) %s does not match earlier (%s) lock", 1407 description, lock_class->lc_name, 1408 w->w_class->lc_name); 1409 return (w); 1410 } 1411 } 1412 /* 1413 * We issue a warning for any spin locks not defined in the static 1414 * order list as a way to discourage their use (folks should really 1415 * be using non-spin mutexes most of the time). However, several 1416 * 3rd part device drivers use spin locks because that is all they 1417 * have available on Windows and Linux and they think that normal 1418 * mutexes are insufficient. 1419 */ 1420 if ((lock_class->lc_flags & LC_SPINLOCK) && witness_spin_warn) 1421 printf("WITNESS: spin lock %s not in order list", description); 1422 if ((w = witness_get()) == NULL) 1423 return (NULL); 1424 w->w_name = description; 1425 w->w_class = lock_class; 1426 w->w_refcount = 1; 1427 STAILQ_INSERT_HEAD(&w_all, w, w_list); 1428 if (lock_class->lc_flags & LC_SPINLOCK) { 1429 STAILQ_INSERT_HEAD(&w_spin, w, w_typelist); 1430 w_spin_cnt++; 1431 } else if (lock_class->lc_flags & LC_SLEEPLOCK) { 1432 STAILQ_INSERT_HEAD(&w_sleep, w, w_typelist); 1433 w_sleep_cnt++; 1434 } else { 1435 mtx_unlock_spin(&w_mtx); 1436 panic("lock class %s is not sleep or spin", 1437 lock_class->lc_name); 1438 } 1439 mtx_unlock_spin(&w_mtx); 1440 return (w); 1441 } 1442 1443 /* Don't let the door bang you on the way out... */ 1444 static int 1445 depart(struct witness *w) 1446 { 1447 struct witness_child_list_entry *wcl, *nwcl; 1448 struct witness_list *list; 1449 struct witness *parent; 1450 1451 MPASS(w->w_refcount == 0); 1452 if (w->w_class->lc_flags & LC_SLEEPLOCK) { 1453 list = &w_sleep; 1454 w_sleep_cnt--; 1455 } else { 1456 list = &w_spin; 1457 w_spin_cnt--; 1458 } 1459 /* 1460 * First, we run through the entire tree looking for any 1461 * witnesses that the outgoing witness is a child of. For 1462 * each parent that we find, we reparent all the direct 1463 * children of the outgoing witness to its parent. 1464 */ 1465 STAILQ_FOREACH(parent, list, w_typelist) { 1466 if (!isitmychild(parent, w)) 1467 continue; 1468 removechild(parent, w); 1469 } 1470 1471 /* 1472 * Now we go through and free up the child list of the 1473 * outgoing witness. 1474 */ 1475 for (wcl = w->w_children; wcl != NULL; wcl = nwcl) { 1476 nwcl = wcl->wcl_next; 1477 w_child_cnt--; 1478 witness_child_free(wcl); 1479 } 1480 1481 /* 1482 * Detach from various lists and free. 1483 */ 1484 STAILQ_REMOVE(list, w, witness, w_typelist); 1485 STAILQ_REMOVE(&w_all, w, witness, w_list); 1486 witness_free(w); 1487 1488 return (1); 1489 } 1490 1491 /* 1492 * Add "child" as a direct child of "parent". Returns false if 1493 * we fail due to out of memory. 1494 */ 1495 static int 1496 insertchild(struct witness *parent, struct witness *child) 1497 { 1498 struct witness_child_list_entry **wcl; 1499 1500 MPASS(child != NULL && parent != NULL); 1501 1502 /* 1503 * Insert "child" after "parent" 1504 */ 1505 wcl = &parent->w_children; 1506 while (*wcl != NULL && (*wcl)->wcl_count == WITNESS_NCHILDREN) 1507 wcl = &(*wcl)->wcl_next; 1508 if (*wcl == NULL) { 1509 *wcl = witness_child_get(); 1510 if (*wcl == NULL) 1511 return (0); 1512 w_child_cnt++; 1513 } 1514 (*wcl)->wcl_children[(*wcl)->wcl_count++] = child; 1515 1516 return (1); 1517 } 1518 1519 1520 static int 1521 itismychild(struct witness *parent, struct witness *child) 1522 { 1523 struct witness_list *list; 1524 1525 MPASS(child != NULL && parent != NULL); 1526 if ((parent->w_class->lc_flags & (LC_SLEEPLOCK | LC_SPINLOCK)) != 1527 (child->w_class->lc_flags & (LC_SLEEPLOCK | LC_SPINLOCK))) 1528 panic( 1529 "%s: parent (%s) and child (%s) are not the same lock type", 1530 __func__, parent->w_class->lc_name, 1531 child->w_class->lc_name); 1532 1533 if (!insertchild(parent, child)) 1534 return (0); 1535 1536 if (parent->w_class->lc_flags & LC_SLEEPLOCK) 1537 list = &w_sleep; 1538 else 1539 list = &w_spin; 1540 return (1); 1541 } 1542 1543 static void 1544 removechild(struct witness *parent, struct witness *child) 1545 { 1546 struct witness_child_list_entry **wcl, *wcl1; 1547 int i; 1548 1549 for (wcl = &parent->w_children; *wcl != NULL; wcl = &(*wcl)->wcl_next) 1550 for (i = 0; i < (*wcl)->wcl_count; i++) 1551 if ((*wcl)->wcl_children[i] == child) 1552 goto found; 1553 return; 1554 found: 1555 (*wcl)->wcl_count--; 1556 if ((*wcl)->wcl_count > i) 1557 (*wcl)->wcl_children[i] = 1558 (*wcl)->wcl_children[(*wcl)->wcl_count]; 1559 MPASS((*wcl)->wcl_children[i] != NULL); 1560 if ((*wcl)->wcl_count != 0) 1561 return; 1562 wcl1 = *wcl; 1563 *wcl = wcl1->wcl_next; 1564 w_child_cnt--; 1565 witness_child_free(wcl1); 1566 } 1567 1568 static int 1569 isitmychild(struct witness *parent, struct witness *child) 1570 { 1571 struct witness_child_list_entry *wcl; 1572 int i; 1573 1574 for (wcl = parent->w_children; wcl != NULL; wcl = wcl->wcl_next) { 1575 for (i = 0; i < wcl->wcl_count; i++) { 1576 if (wcl->wcl_children[i] == child) 1577 return (1); 1578 } 1579 } 1580 return (0); 1581 } 1582 1583 static int 1584 isitmydescendant(struct witness *parent, struct witness *child) 1585 { 1586 struct witness_child_list_entry *wcl; 1587 int i, j; 1588 1589 if (isitmychild(parent, child)) 1590 return (1); 1591 j = 0; 1592 for (wcl = parent->w_children; wcl != NULL; wcl = wcl->wcl_next) { 1593 MPASS(j < 1000); 1594 for (i = 0; i < wcl->wcl_count; i++) { 1595 if (isitmydescendant(wcl->wcl_children[i], child)) 1596 return (1); 1597 } 1598 j++; 1599 } 1600 return (0); 1601 } 1602 1603 #ifdef BLESSING 1604 static int 1605 blessed(struct witness *w1, struct witness *w2) 1606 { 1607 int i; 1608 struct witness_blessed *b; 1609 1610 for (i = 0; i < blessed_count; i++) { 1611 b = &blessed_list[i]; 1612 if (strcmp(w1->w_name, b->b_lock1) == 0) { 1613 if (strcmp(w2->w_name, b->b_lock2) == 0) 1614 return (1); 1615 continue; 1616 } 1617 if (strcmp(w1->w_name, b->b_lock2) == 0) 1618 if (strcmp(w2->w_name, b->b_lock1) == 0) 1619 return (1); 1620 } 1621 return (0); 1622 } 1623 #endif 1624 1625 static struct witness * 1626 witness_get(void) 1627 { 1628 struct witness *w; 1629 1630 if (witness_watch == 0) { 1631 mtx_unlock_spin(&w_mtx); 1632 return (NULL); 1633 } 1634 if (STAILQ_EMPTY(&w_free)) { 1635 witness_watch = 0; 1636 mtx_unlock_spin(&w_mtx); 1637 printf("%s: witness exhausted\n", __func__); 1638 return (NULL); 1639 } 1640 w = STAILQ_FIRST(&w_free); 1641 STAILQ_REMOVE_HEAD(&w_free, w_list); 1642 w_free_cnt--; 1643 bzero(w, sizeof(*w)); 1644 return (w); 1645 } 1646 1647 static void 1648 witness_free(struct witness *w) 1649 { 1650 1651 STAILQ_INSERT_HEAD(&w_free, w, w_list); 1652 w_free_cnt++; 1653 } 1654 1655 static struct witness_child_list_entry * 1656 witness_child_get(void) 1657 { 1658 struct witness_child_list_entry *wcl; 1659 1660 if (witness_watch == 0) { 1661 mtx_unlock_spin(&w_mtx); 1662 return (NULL); 1663 } 1664 wcl = w_child_free; 1665 if (wcl == NULL) { 1666 witness_watch = 0; 1667 mtx_unlock_spin(&w_mtx); 1668 printf("%s: witness exhausted\n", __func__); 1669 return (NULL); 1670 } 1671 w_child_free = wcl->wcl_next; 1672 w_child_free_cnt--; 1673 bzero(wcl, sizeof(*wcl)); 1674 return (wcl); 1675 } 1676 1677 static void 1678 witness_child_free(struct witness_child_list_entry *wcl) 1679 { 1680 1681 wcl->wcl_next = w_child_free; 1682 w_child_free = wcl; 1683 w_child_free_cnt++; 1684 } 1685 1686 static struct lock_list_entry * 1687 witness_lock_list_get(void) 1688 { 1689 struct lock_list_entry *lle; 1690 1691 if (witness_watch == 0) 1692 return (NULL); 1693 mtx_lock_spin(&w_mtx); 1694 lle = w_lock_list_free; 1695 if (lle == NULL) { 1696 witness_watch = 0; 1697 mtx_unlock_spin(&w_mtx); 1698 printf("%s: witness exhausted\n", __func__); 1699 return (NULL); 1700 } 1701 w_lock_list_free = lle->ll_next; 1702 mtx_unlock_spin(&w_mtx); 1703 bzero(lle, sizeof(*lle)); 1704 return (lle); 1705 } 1706 1707 static void 1708 witness_lock_list_free(struct lock_list_entry *lle) 1709 { 1710 1711 mtx_lock_spin(&w_mtx); 1712 lle->ll_next = w_lock_list_free; 1713 w_lock_list_free = lle; 1714 mtx_unlock_spin(&w_mtx); 1715 } 1716 1717 static struct lock_instance * 1718 find_instance(struct lock_list_entry *lock_list, struct lock_object *lock) 1719 { 1720 struct lock_list_entry *lle; 1721 struct lock_instance *instance; 1722 int i; 1723 1724 for (lle = lock_list; lle != NULL; lle = lle->ll_next) 1725 for (i = lle->ll_count - 1; i >= 0; i--) { 1726 instance = &lle->ll_children[i]; 1727 if (instance->li_lock == lock) 1728 return (instance); 1729 } 1730 return (NULL); 1731 } 1732 1733 static void 1734 witness_list_lock(struct lock_instance *instance) 1735 { 1736 struct lock_object *lock; 1737 1738 lock = instance->li_lock; 1739 printf("%s %s %s", (instance->li_flags & LI_EXCLUSIVE) != 0 ? 1740 "exclusive" : "shared", lock->lo_class->lc_name, lock->lo_name); 1741 if (lock->lo_type != lock->lo_name) 1742 printf(" (%s)", lock->lo_type); 1743 printf(" r = %d (%p) locked @ %s:%d\n", 1744 instance->li_flags & LI_RECURSEMASK, lock, instance->li_file, 1745 instance->li_line); 1746 } 1747 1748 #ifdef DDB 1749 static int 1750 witness_thread_has_locks(struct thread *td) 1751 { 1752 1753 return (td->td_sleeplocks != NULL); 1754 } 1755 1756 static int 1757 witness_proc_has_locks(struct proc *p) 1758 { 1759 struct thread *td; 1760 1761 FOREACH_THREAD_IN_PROC(p, td) { 1762 if (witness_thread_has_locks(td)) 1763 return (1); 1764 } 1765 return (0); 1766 } 1767 #endif 1768 1769 int 1770 witness_list_locks(struct lock_list_entry **lock_list) 1771 { 1772 struct lock_list_entry *lle; 1773 int i, nheld; 1774 1775 nheld = 0; 1776 for (lle = *lock_list; lle != NULL; lle = lle->ll_next) 1777 for (i = lle->ll_count - 1; i >= 0; i--) { 1778 witness_list_lock(&lle->ll_children[i]); 1779 nheld++; 1780 } 1781 return (nheld); 1782 } 1783 1784 /* 1785 * This is a bit risky at best. We call this function when we have timed 1786 * out acquiring a spin lock, and we assume that the other CPU is stuck 1787 * with this lock held. So, we go groveling around in the other CPU's 1788 * per-cpu data to try to find the lock instance for this spin lock to 1789 * see when it was last acquired. 1790 */ 1791 void 1792 witness_display_spinlock(struct lock_object *lock, struct thread *owner) 1793 { 1794 struct lock_instance *instance; 1795 struct pcpu *pc; 1796 1797 if (owner->td_critnest == 0 || owner->td_oncpu == NOCPU) 1798 return; 1799 pc = pcpu_find(owner->td_oncpu); 1800 instance = find_instance(pc->pc_spinlocks, lock); 1801 if (instance != NULL) 1802 witness_list_lock(instance); 1803 } 1804 1805 void 1806 witness_save(struct lock_object *lock, const char **filep, int *linep) 1807 { 1808 struct lock_instance *instance; 1809 1810 KASSERT(!witness_cold, ("%s: witness_cold", __func__)); 1811 if (lock->lo_witness == NULL || witness_watch == 0 || panicstr != NULL) 1812 return; 1813 if ((lock->lo_class->lc_flags & LC_SLEEPLOCK) == 0) 1814 panic("%s: lock (%s) %s is not a sleep lock", __func__, 1815 lock->lo_class->lc_name, lock->lo_name); 1816 instance = find_instance(curthread->td_sleeplocks, lock); 1817 if (instance == NULL) 1818 panic("%s: lock (%s) %s not locked", __func__, 1819 lock->lo_class->lc_name, lock->lo_name); 1820 *filep = instance->li_file; 1821 *linep = instance->li_line; 1822 } 1823 1824 void 1825 witness_restore(struct lock_object *lock, const char *file, int line) 1826 { 1827 struct lock_instance *instance; 1828 1829 KASSERT(!witness_cold, ("%s: witness_cold", __func__)); 1830 if (lock->lo_witness == NULL || witness_watch == 0 || panicstr != NULL) 1831 return; 1832 if ((lock->lo_class->lc_flags & LC_SLEEPLOCK) == 0) 1833 panic("%s: lock (%s) %s is not a sleep lock", __func__, 1834 lock->lo_class->lc_name, lock->lo_name); 1835 instance = find_instance(curthread->td_sleeplocks, lock); 1836 if (instance == NULL) 1837 panic("%s: lock (%s) %s not locked", __func__, 1838 lock->lo_class->lc_name, lock->lo_name); 1839 lock->lo_witness->w_file = file; 1840 lock->lo_witness->w_line = line; 1841 instance->li_file = file; 1842 instance->li_line = line; 1843 } 1844 1845 void 1846 witness_assert(struct lock_object *lock, int flags, const char *file, int line) 1847 { 1848 #ifdef INVARIANT_SUPPORT 1849 struct lock_instance *instance; 1850 1851 if (lock->lo_witness == NULL || witness_watch == 0 || panicstr != NULL) 1852 return; 1853 if ((lock->lo_class->lc_flags & LC_SLEEPLOCK) != 0) 1854 instance = find_instance(curthread->td_sleeplocks, lock); 1855 else if ((lock->lo_class->lc_flags & LC_SPINLOCK) != 0) 1856 instance = find_instance(PCPU_GET(spinlocks), lock); 1857 else { 1858 panic("Lock (%s) %s is not sleep or spin!", 1859 lock->lo_class->lc_name, lock->lo_name); 1860 } 1861 file = fixup_filename(file); 1862 switch (flags) { 1863 case LA_UNLOCKED: 1864 if (instance != NULL) 1865 panic("Lock (%s) %s locked @ %s:%d.", 1866 lock->lo_class->lc_name, lock->lo_name, file, line); 1867 break; 1868 case LA_LOCKED: 1869 case LA_LOCKED | LA_RECURSED: 1870 case LA_LOCKED | LA_NOTRECURSED: 1871 case LA_SLOCKED: 1872 case LA_SLOCKED | LA_RECURSED: 1873 case LA_SLOCKED | LA_NOTRECURSED: 1874 case LA_XLOCKED: 1875 case LA_XLOCKED | LA_RECURSED: 1876 case LA_XLOCKED | LA_NOTRECURSED: 1877 if (instance == NULL) { 1878 panic("Lock (%s) %s not locked @ %s:%d.", 1879 lock->lo_class->lc_name, lock->lo_name, file, line); 1880 break; 1881 } 1882 if ((flags & LA_XLOCKED) != 0 && 1883 (instance->li_flags & LI_EXCLUSIVE) == 0) 1884 panic("Lock (%s) %s not exclusively locked @ %s:%d.", 1885 lock->lo_class->lc_name, lock->lo_name, file, line); 1886 if ((flags & LA_SLOCKED) != 0 && 1887 (instance->li_flags & LI_EXCLUSIVE) != 0) 1888 panic("Lock (%s) %s exclusively locked @ %s:%d.", 1889 lock->lo_class->lc_name, lock->lo_name, file, line); 1890 if ((flags & LA_RECURSED) != 0 && 1891 (instance->li_flags & LI_RECURSEMASK) == 0) 1892 panic("Lock (%s) %s not recursed @ %s:%d.", 1893 lock->lo_class->lc_name, lock->lo_name, file, line); 1894 if ((flags & LA_NOTRECURSED) != 0 && 1895 (instance->li_flags & LI_RECURSEMASK) != 0) 1896 panic("Lock (%s) %s recursed @ %s:%d.", 1897 lock->lo_class->lc_name, lock->lo_name, file, line); 1898 break; 1899 default: 1900 panic("Invalid lock assertion at %s:%d.", file, line); 1901 1902 } 1903 #endif /* INVARIANT_SUPPORT */ 1904 } 1905 1906 #ifdef DDB 1907 static void 1908 witness_list(struct thread *td) 1909 { 1910 1911 KASSERT(!witness_cold, ("%s: witness_cold", __func__)); 1912 KASSERT(kdb_active, ("%s: not in the debugger", __func__)); 1913 1914 if (witness_watch == 0) 1915 return; 1916 1917 witness_list_locks(&td->td_sleeplocks); 1918 1919 /* 1920 * We only handle spinlocks if td == curthread. This is somewhat broken 1921 * if td is currently executing on some other CPU and holds spin locks 1922 * as we won't display those locks. If we had a MI way of getting 1923 * the per-cpu data for a given cpu then we could use 1924 * td->td_oncpu to get the list of spinlocks for this thread 1925 * and "fix" this. 1926 * 1927 * That still wouldn't really fix this unless we locked sched_lock 1928 * or stopped the other CPU to make sure it wasn't changing the list 1929 * out from under us. It is probably best to just not try to handle 1930 * threads on other CPU's for now. 1931 */ 1932 if (td == curthread && PCPU_GET(spinlocks) != NULL) 1933 witness_list_locks(PCPU_PTR(spinlocks)); 1934 } 1935 1936 DB_SHOW_COMMAND(locks, db_witness_list) 1937 { 1938 struct thread *td; 1939 pid_t pid; 1940 struct proc *p; 1941 1942 if (have_addr) { 1943 pid = (addr % 16) + ((addr >> 4) % 16) * 10 + 1944 ((addr >> 8) % 16) * 100 + ((addr >> 12) % 16) * 1000 + 1945 ((addr >> 16) % 16) * 10000; 1946 /* sx_slock(&allproc_lock); */ 1947 FOREACH_PROC_IN_SYSTEM(p) { 1948 if (p->p_pid == pid) 1949 break; 1950 } 1951 /* sx_sunlock(&allproc_lock); */ 1952 if (p == NULL) { 1953 db_printf("pid %d not found\n", pid); 1954 return; 1955 } 1956 FOREACH_THREAD_IN_PROC(p, td) { 1957 witness_list(td); 1958 } 1959 } else { 1960 td = curthread; 1961 witness_list(td); 1962 } 1963 } 1964 1965 DB_SHOW_COMMAND(alllocks, db_witness_list_all) 1966 { 1967 struct thread *td; 1968 struct proc *p; 1969 1970 /* 1971 * It would be nice to list only threads and processes that actually 1972 * held sleep locks, but that information is currently not exported 1973 * by WITNESS. 1974 */ 1975 FOREACH_PROC_IN_SYSTEM(p) { 1976 if (!witness_proc_has_locks(p)) 1977 continue; 1978 FOREACH_THREAD_IN_PROC(p, td) { 1979 if (!witness_thread_has_locks(td)) 1980 continue; 1981 printf("Process %d (%s) thread %p (%d)\n", p->p_pid, 1982 p->p_comm, td, td->td_tid); 1983 witness_list(td); 1984 } 1985 } 1986 } 1987 1988 DB_SHOW_COMMAND(witness, db_witness_display) 1989 { 1990 1991 witness_display(db_printf); 1992 } 1993 #endif 1994