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 /* Note that these traces do not work with KTR_ALQ. */ 107 #if 0 108 #define KTR_WITNESS KTR_SUBSYS 109 #else 110 #define KTR_WITNESS 0 111 #endif 112 113 /* Easier to stay with the old names. */ 114 #define lo_list lo_witness_data.lod_list 115 #define lo_witness lo_witness_data.lod_witness 116 117 /* Define this to check for blessed mutexes */ 118 #undef BLESSING 119 120 #define WITNESS_COUNT 1024 121 #define WITNESS_CHILDCOUNT (WITNESS_COUNT * 4) 122 /* 123 * XXX: This is somewhat bogus, as we assume here that at most 1024 threads 124 * will hold LOCK_NCHILDREN * 2 locks. We handle failure ok, and we should 125 * probably be safe for the most part, but it's still a SWAG. 126 */ 127 #define LOCK_CHILDCOUNT (MAXCPU + 1024) * 2 128 129 #define WITNESS_NCHILDREN 6 130 131 struct witness_child_list_entry; 132 133 struct witness { 134 const char *w_name; 135 struct lock_class *w_class; 136 STAILQ_ENTRY(witness) w_list; /* List of all witnesses. */ 137 STAILQ_ENTRY(witness) w_typelist; /* Witnesses of a type. */ 138 struct witness_child_list_entry *w_children; /* Great evilness... */ 139 const char *w_file; 140 int w_line; 141 u_int w_level; 142 u_int w_refcount; 143 u_char w_Giant_squawked:1; 144 u_char w_other_squawked:1; 145 u_char w_same_squawked:1; 146 u_char w_displayed:1; 147 }; 148 149 struct witness_child_list_entry { 150 struct witness_child_list_entry *wcl_next; 151 struct witness *wcl_children[WITNESS_NCHILDREN]; 152 u_int wcl_count; 153 }; 154 155 STAILQ_HEAD(witness_list, witness); 156 157 #ifdef BLESSING 158 struct witness_blessed { 159 const char *b_lock1; 160 const char *b_lock2; 161 }; 162 #endif 163 164 struct witness_order_list_entry { 165 const char *w_name; 166 struct lock_class *w_class; 167 }; 168 169 #ifdef BLESSING 170 static int blessed(struct witness *, struct witness *); 171 #endif 172 static int depart(struct witness *w); 173 static struct witness *enroll(const char *description, 174 struct lock_class *lock_class); 175 static int insertchild(struct witness *parent, struct witness *child); 176 static int isitmychild(struct witness *parent, struct witness *child); 177 static int isitmydescendant(struct witness *parent, struct witness *child); 178 static int itismychild(struct witness *parent, struct witness *child); 179 static void removechild(struct witness *parent, struct witness *child); 180 static int sysctl_debug_witness_watch(SYSCTL_HANDLER_ARGS); 181 static const char *fixup_filename(const char *file); 182 static struct witness *witness_get(void); 183 static void witness_free(struct witness *m); 184 static struct witness_child_list_entry *witness_child_get(void); 185 static void witness_child_free(struct witness_child_list_entry *wcl); 186 static struct lock_list_entry *witness_lock_list_get(void); 187 static void witness_lock_list_free(struct lock_list_entry *lle); 188 static struct lock_instance *find_instance(struct lock_list_entry *lock_list, 189 struct lock_object *lock); 190 static void witness_list_lock(struct lock_instance *instance); 191 #ifdef DDB 192 static void witness_leveldescendents(struct witness *parent, int level); 193 static void witness_levelall(void); 194 static void witness_displaydescendants(void(*)(const char *fmt, ...), 195 struct witness *, int indent); 196 static void witness_display_list(void(*prnt)(const char *fmt, ...), 197 struct witness_list *list); 198 static void witness_display(void(*)(const char *fmt, ...)); 199 static void witness_list(struct thread *td); 200 #endif 201 202 SYSCTL_NODE(_debug, OID_AUTO, witness, CTLFLAG_RW, 0, "Witness Locking"); 203 204 /* 205 * If set to 0, witness is disabled. If set to a non-zero value, witness 206 * performs full lock order checking for all locks. At runtime, this 207 * value may be set to 0 to turn off witness. witness is not allowed be 208 * turned on once it is turned off, however. 209 */ 210 static int witness_watch = 1; 211 TUNABLE_INT("debug.witness.watch", &witness_watch); 212 SYSCTL_PROC(_debug_witness, OID_AUTO, watch, CTLFLAG_RW | CTLTYPE_INT, NULL, 0, 213 sysctl_debug_witness_watch, "I", "witness is watching lock operations"); 214 215 #ifdef KDB 216 /* 217 * When KDB is enabled and witness_kdb is set to 1, it will cause the system 218 * to drop into kdebug() when: 219 * - a lock hierarchy violation occurs 220 * - locks are held when going to sleep. 221 */ 222 #ifdef WITNESS_KDB 223 int witness_kdb = 1; 224 #else 225 int witness_kdb = 0; 226 #endif 227 TUNABLE_INT("debug.witness.kdb", &witness_kdb); 228 SYSCTL_INT(_debug_witness, OID_AUTO, kdb, CTLFLAG_RW, &witness_kdb, 0, ""); 229 230 /* 231 * When KDB is enabled and witness_trace is set to 1, it will cause the system 232 * to print a stack trace: 233 * - a lock hierarchy violation occurs 234 * - locks are held when going to sleep. 235 */ 236 int witness_trace = 1; 237 TUNABLE_INT("debug.witness.trace", &witness_trace); 238 SYSCTL_INT(_debug_witness, OID_AUTO, trace, CTLFLAG_RW, &witness_trace, 0, ""); 239 #endif /* KDB */ 240 241 #ifdef WITNESS_SKIPSPIN 242 int witness_skipspin = 1; 243 #else 244 int witness_skipspin = 0; 245 #endif 246 TUNABLE_INT("debug.witness.skipspin", &witness_skipspin); 247 SYSCTL_INT(_debug_witness, OID_AUTO, skipspin, CTLFLAG_RDTUN, 248 &witness_skipspin, 0, ""); 249 250 static struct mtx w_mtx; 251 static struct witness_list w_free = STAILQ_HEAD_INITIALIZER(w_free); 252 static struct witness_list w_all = STAILQ_HEAD_INITIALIZER(w_all); 253 static struct witness_list w_spin = STAILQ_HEAD_INITIALIZER(w_spin); 254 static struct witness_list w_sleep = STAILQ_HEAD_INITIALIZER(w_sleep); 255 static struct witness_child_list_entry *w_child_free = NULL; 256 static struct lock_list_entry *w_lock_list_free = NULL; 257 258 static int w_free_cnt, w_spin_cnt, w_sleep_cnt, w_child_free_cnt, w_child_cnt; 259 SYSCTL_INT(_debug_witness, OID_AUTO, free_cnt, CTLFLAG_RD, &w_free_cnt, 0, ""); 260 SYSCTL_INT(_debug_witness, OID_AUTO, spin_cnt, CTLFLAG_RD, &w_spin_cnt, 0, ""); 261 SYSCTL_INT(_debug_witness, OID_AUTO, sleep_cnt, CTLFLAG_RD, &w_sleep_cnt, 0, 262 ""); 263 SYSCTL_INT(_debug_witness, OID_AUTO, child_free_cnt, CTLFLAG_RD, 264 &w_child_free_cnt, 0, ""); 265 SYSCTL_INT(_debug_witness, OID_AUTO, child_cnt, CTLFLAG_RD, &w_child_cnt, 0, 266 ""); 267 268 static struct witness w_data[WITNESS_COUNT]; 269 static struct witness_child_list_entry w_childdata[WITNESS_CHILDCOUNT]; 270 static struct lock_list_entry w_locklistdata[LOCK_CHILDCOUNT]; 271 272 static struct witness_order_list_entry order_lists[] = { 273 /* 274 * sx locks 275 */ 276 { "proctree", &lock_class_sx }, 277 { "allproc", &lock_class_sx }, 278 { NULL, NULL }, 279 /* 280 * Various mutexes 281 */ 282 { "Giant", &lock_class_mtx_sleep }, 283 { "filedesc structure", &lock_class_mtx_sleep }, 284 { "pipe mutex", &lock_class_mtx_sleep }, 285 { "sigio lock", &lock_class_mtx_sleep }, 286 { "process group", &lock_class_mtx_sleep }, 287 { "process lock", &lock_class_mtx_sleep }, 288 { "session", &lock_class_mtx_sleep }, 289 { "uidinfo hash", &lock_class_mtx_sleep }, 290 { "uidinfo struct", &lock_class_mtx_sleep }, 291 { "allprison", &lock_class_mtx_sleep }, 292 { NULL, NULL }, 293 /* 294 * Sockets 295 */ 296 { "filedesc structure", &lock_class_mtx_sleep }, 297 { "accept", &lock_class_mtx_sleep }, 298 { "so_snd", &lock_class_mtx_sleep }, 299 { "so_rcv", &lock_class_mtx_sleep }, 300 { "sellck", &lock_class_mtx_sleep }, 301 { NULL, NULL }, 302 /* 303 * Routing 304 */ 305 { "so_rcv", &lock_class_mtx_sleep }, 306 { "radix node head", &lock_class_mtx_sleep }, 307 { "rtentry", &lock_class_mtx_sleep }, 308 { "ifaddr", &lock_class_mtx_sleep }, 309 { NULL, NULL }, 310 /* 311 * Multicast - protocol locks before interface locks, after UDP locks. 312 */ 313 { "udpinp", &lock_class_mtx_sleep }, 314 { "in_multi_mtx", &lock_class_mtx_sleep }, 315 { "igmp_mtx", &lock_class_mtx_sleep }, 316 { "if_addr_mtx", &lock_class_mtx_sleep }, 317 { NULL, NULL }, 318 /* 319 * UNIX Domain Sockets 320 */ 321 { "unp", &lock_class_mtx_sleep }, 322 { "so_snd", &lock_class_mtx_sleep }, 323 { NULL, NULL }, 324 /* 325 * UDP/IP 326 */ 327 { "udp", &lock_class_mtx_sleep }, 328 { "udpinp", &lock_class_mtx_sleep }, 329 { "so_snd", &lock_class_mtx_sleep }, 330 { NULL, NULL }, 331 /* 332 * TCP/IP 333 */ 334 { "tcp", &lock_class_mtx_sleep }, 335 { "tcpinp", &lock_class_mtx_sleep }, 336 { "so_snd", &lock_class_mtx_sleep }, 337 { NULL, NULL }, 338 /* 339 * SLIP 340 */ 341 { "slip_mtx", &lock_class_mtx_sleep }, 342 { "slip sc_mtx", &lock_class_mtx_sleep }, 343 { NULL, NULL }, 344 /* 345 * netatalk 346 */ 347 { "ddp_list_mtx", &lock_class_mtx_sleep }, 348 { "ddp_mtx", &lock_class_mtx_sleep }, 349 { NULL, NULL }, 350 /* 351 * BPF 352 */ 353 { "bpf global lock", &lock_class_mtx_sleep }, 354 { "bpf interface lock", &lock_class_mtx_sleep }, 355 { "bpf cdev lock", &lock_class_mtx_sleep }, 356 { NULL, NULL }, 357 /* 358 * NFS server 359 */ 360 { "nfsd_mtx", &lock_class_mtx_sleep }, 361 { "so_snd", &lock_class_mtx_sleep }, 362 { NULL, NULL }, 363 /* 364 * CDEV 365 */ 366 { "system map", &lock_class_mtx_sleep }, 367 { "vm page queue mutex", &lock_class_mtx_sleep }, 368 { "vnode interlock", &lock_class_mtx_sleep }, 369 { "cdev", &lock_class_mtx_sleep }, 370 { NULL, NULL }, 371 /* 372 * spin locks 373 */ 374 #ifdef SMP 375 { "ap boot", &lock_class_mtx_spin }, 376 #endif 377 { "rm.mutex_mtx", &lock_class_mtx_spin }, 378 { "hptlock", &lock_class_mtx_spin }, 379 { "sio", &lock_class_mtx_spin }, 380 #ifdef __i386__ 381 { "cy", &lock_class_mtx_spin }, 382 #endif 383 { "uart_hwmtx", &lock_class_mtx_spin }, 384 { "sabtty", &lock_class_mtx_spin }, 385 { "zstty", &lock_class_mtx_spin }, 386 { "ng_node", &lock_class_mtx_spin }, 387 { "ng_worklist", &lock_class_mtx_spin }, 388 { "taskqueue_fast", &lock_class_mtx_spin }, 389 { "intr table", &lock_class_mtx_spin }, 390 { "sleepq chain", &lock_class_mtx_spin }, 391 { "sched lock", &lock_class_mtx_spin }, 392 { "turnstile chain", &lock_class_mtx_spin }, 393 { "td_contested", &lock_class_mtx_spin }, 394 { "callout", &lock_class_mtx_spin }, 395 { "entropy harvest mutex", &lock_class_mtx_spin }, 396 /* 397 * leaf locks 398 */ 399 { "allpmaps", &lock_class_mtx_spin }, 400 { "vm page queue free mutex", &lock_class_mtx_spin }, 401 { "icu", &lock_class_mtx_spin }, 402 #ifdef SMP 403 { "smp rendezvous", &lock_class_mtx_spin }, 404 #if defined(__i386__) || defined(__amd64__) 405 { "tlb", &lock_class_mtx_spin }, 406 #endif 407 #ifdef __sparc64__ 408 { "ipi", &lock_class_mtx_spin }, 409 { "rtc_mtx", &lock_class_mtx_spin }, 410 #endif 411 #endif 412 { "clk", &lock_class_mtx_spin }, 413 { "mutex profiling lock", &lock_class_mtx_spin }, 414 { "kse zombie lock", &lock_class_mtx_spin }, 415 { "ALD Queue", &lock_class_mtx_spin }, 416 #ifdef __ia64__ 417 { "MCA spin lock", &lock_class_mtx_spin }, 418 #endif 419 #if defined(__i386__) || defined(__amd64__) 420 { "pcicfg", &lock_class_mtx_spin }, 421 { "NDIS thread lock", &lock_class_mtx_spin }, 422 #endif 423 { "tw_osl_io_lock", &lock_class_mtx_spin }, 424 { "tw_osl_q_lock", &lock_class_mtx_spin }, 425 { "tw_cl_io_lock", &lock_class_mtx_spin }, 426 { "tw_cl_intr_lock", &lock_class_mtx_spin }, 427 { "tw_cl_gen_lock", &lock_class_mtx_spin }, 428 { NULL, NULL }, 429 { NULL, NULL } 430 }; 431 432 #ifdef BLESSING 433 /* 434 * Pairs of locks which have been blessed 435 * Don't complain about order problems with blessed locks 436 */ 437 static struct witness_blessed blessed_list[] = { 438 }; 439 static int blessed_count = 440 sizeof(blessed_list) / sizeof(struct witness_blessed); 441 #endif 442 443 /* 444 * List of locks initialized prior to witness being initialized whose 445 * enrollment is currently deferred. 446 */ 447 STAILQ_HEAD(, lock_object) pending_locks = 448 STAILQ_HEAD_INITIALIZER(pending_locks); 449 450 /* 451 * This global is set to 0 once it becomes safe to use the witness code. 452 */ 453 static int witness_cold = 1; 454 455 /* 456 * This global is set to 1 once the static lock orders have been enrolled 457 * so that a warning can be issued for any spin locks enrolled later. 458 */ 459 static int witness_spin_warn = 0; 460 461 /* 462 * The WITNESS-enabled diagnostic code. Note that the witness code does 463 * assume that the early boot is single-threaded at least until after this 464 * routine is completed. 465 */ 466 static void 467 witness_initialize(void *dummy __unused) 468 { 469 struct lock_object *lock; 470 struct witness_order_list_entry *order; 471 struct witness *w, *w1; 472 int i; 473 474 /* 475 * We have to release Giant before initializing its witness 476 * structure so that WITNESS doesn't get confused. 477 */ 478 mtx_unlock(&Giant); 479 mtx_assert(&Giant, MA_NOTOWNED); 480 481 CTR1(KTR_WITNESS, "%s: initializing witness", __func__); 482 mtx_init(&w_mtx, "witness lock", NULL, MTX_SPIN | MTX_QUIET | 483 MTX_NOWITNESS); 484 for (i = 0; i < WITNESS_COUNT; i++) 485 witness_free(&w_data[i]); 486 for (i = 0; i < WITNESS_CHILDCOUNT; i++) 487 witness_child_free(&w_childdata[i]); 488 for (i = 0; i < LOCK_CHILDCOUNT; i++) 489 witness_lock_list_free(&w_locklistdata[i]); 490 491 /* First add in all the specified order lists. */ 492 for (order = order_lists; order->w_name != NULL; order++) { 493 w = enroll(order->w_name, order->w_class); 494 if (w == NULL) 495 continue; 496 w->w_file = "order list"; 497 for (order++; order->w_name != NULL; order++) { 498 w1 = enroll(order->w_name, order->w_class); 499 if (w1 == NULL) 500 continue; 501 w1->w_file = "order list"; 502 if (!itismychild(w, w1)) 503 panic("Not enough memory for static orders!"); 504 w = w1; 505 } 506 } 507 witness_spin_warn = 1; 508 509 /* Iterate through all locks and add them to witness. */ 510 while (!STAILQ_EMPTY(&pending_locks)) { 511 lock = STAILQ_FIRST(&pending_locks); 512 STAILQ_REMOVE_HEAD(&pending_locks, lo_list); 513 KASSERT(lock->lo_flags & LO_WITNESS, 514 ("%s: lock %s is on pending list but not LO_WITNESS", 515 __func__, lock->lo_name)); 516 lock->lo_witness = enroll(lock->lo_type, LOCK_CLASS(lock)); 517 } 518 519 /* Mark the witness code as being ready for use. */ 520 witness_cold = 0; 521 522 mtx_lock(&Giant); 523 } 524 SYSINIT(witness_init, SI_SUB_WITNESS, SI_ORDER_FIRST, witness_initialize, NULL) 525 526 static int 527 sysctl_debug_witness_watch(SYSCTL_HANDLER_ARGS) 528 { 529 int error, value; 530 531 value = witness_watch; 532 error = sysctl_handle_int(oidp, &value, 0, req); 533 if (error != 0 || req->newptr == NULL) 534 return (error); 535 error = suser(req->td); 536 if (error != 0) 537 return (error); 538 if (value == witness_watch) 539 return (0); 540 if (value != 0) 541 return (EINVAL); 542 witness_watch = 0; 543 return (0); 544 } 545 546 void 547 witness_init(struct lock_object *lock) 548 { 549 struct lock_class *class; 550 551 /* Various sanity checks. */ 552 class = LOCK_CLASS(lock); 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 /* 567 * If we shouldn't watch this lock, then just clear lo_witness. 568 * Otherwise, if witness_cold is set, then it is too early to 569 * enroll this lock, so defer it to witness_initialize() by adding 570 * it to the pending_locks list. If it is not too early, then enroll 571 * the lock now. 572 */ 573 if (witness_watch == 0 || panicstr != NULL || 574 (lock->lo_flags & LO_WITNESS) == 0) 575 lock->lo_witness = NULL; 576 else if (witness_cold) { 577 STAILQ_INSERT_TAIL(&pending_locks, lock, lo_list); 578 lock->lo_flags |= LO_ENROLLPEND; 579 } else 580 lock->lo_witness = enroll(lock->lo_type, class); 581 } 582 583 void 584 witness_destroy(struct lock_object *lock) 585 { 586 struct lock_class *class; 587 struct witness *w; 588 589 class = LOCK_CLASS(lock); 590 if (witness_cold) 591 panic("lock (%s) %s destroyed while witness_cold", 592 class->lc_name, lock->lo_name); 593 594 /* XXX: need to verify that no one holds the lock */ 595 if ((lock->lo_flags & (LO_WITNESS | LO_ENROLLPEND)) == LO_WITNESS && 596 lock->lo_witness != NULL) { 597 w = lock->lo_witness; 598 mtx_lock_spin(&w_mtx); 599 MPASS(w->w_refcount > 0); 600 w->w_refcount--; 601 602 /* 603 * Lock is already released if we have an allocation failure 604 * and depart() fails. 605 */ 606 if (w->w_refcount != 0 || depart(w)) 607 mtx_unlock_spin(&w_mtx); 608 } 609 610 /* 611 * If this lock is destroyed before witness is up and running, 612 * remove it from the pending list. 613 */ 614 if (lock->lo_flags & LO_ENROLLPEND) { 615 STAILQ_REMOVE(&pending_locks, lock, lock_object, lo_list); 616 lock->lo_flags &= ~LO_ENROLLPEND; 617 } 618 } 619 620 #ifdef DDB 621 static void 622 witness_levelall (void) 623 { 624 struct witness_list *list; 625 struct witness *w, *w1; 626 627 /* 628 * First clear all levels. 629 */ 630 STAILQ_FOREACH(w, &w_all, w_list) { 631 w->w_level = 0; 632 } 633 634 /* 635 * Look for locks with no parent and level all their descendants. 636 */ 637 STAILQ_FOREACH(w, &w_all, w_list) { 638 /* 639 * This is just an optimization, technically we could get 640 * away just walking the all list each time. 641 */ 642 if (w->w_class->lc_flags & LC_SLEEPLOCK) 643 list = &w_sleep; 644 else 645 list = &w_spin; 646 STAILQ_FOREACH(w1, list, w_typelist) { 647 if (isitmychild(w1, w)) 648 goto skip; 649 } 650 witness_leveldescendents(w, 0); 651 skip: 652 ; /* silence GCC 3.x */ 653 } 654 } 655 656 static void 657 witness_leveldescendents(struct witness *parent, int level) 658 { 659 struct witness_child_list_entry *wcl; 660 int i; 661 662 if (parent->w_level < level) 663 parent->w_level = level; 664 level++; 665 for (wcl = parent->w_children; wcl != NULL; wcl = wcl->wcl_next) 666 for (i = 0; i < wcl->wcl_count; i++) 667 witness_leveldescendents(wcl->wcl_children[i], level); 668 } 669 670 static void 671 witness_displaydescendants(void(*prnt)(const char *fmt, ...), 672 struct witness *parent, int indent) 673 { 674 struct witness_child_list_entry *wcl; 675 int i, level; 676 677 level = parent->w_level; 678 prnt("%-2d", level); 679 for (i = 0; i < indent; i++) 680 prnt(" "); 681 if (parent->w_refcount > 0) 682 prnt("%s", parent->w_name); 683 else 684 prnt("(dead)"); 685 if (parent->w_displayed) { 686 prnt(" -- (already displayed)\n"); 687 return; 688 } 689 parent->w_displayed = 1; 690 if (parent->w_refcount > 0) { 691 if (parent->w_file != NULL) 692 prnt(" -- last acquired @ %s:%d", parent->w_file, 693 parent->w_line); 694 } 695 prnt("\n"); 696 for (wcl = parent->w_children; wcl != NULL; wcl = wcl->wcl_next) 697 for (i = 0; i < wcl->wcl_count; i++) 698 witness_displaydescendants(prnt, 699 wcl->wcl_children[i], indent + 1); 700 } 701 702 static void 703 witness_display_list(void(*prnt)(const char *fmt, ...), 704 struct witness_list *list) 705 { 706 struct witness *w; 707 708 STAILQ_FOREACH(w, list, w_typelist) { 709 if (w->w_file == NULL || w->w_level > 0) 710 continue; 711 /* 712 * This lock has no anscestors, display its descendants. 713 */ 714 witness_displaydescendants(prnt, w, 0); 715 } 716 } 717 718 static void 719 witness_display(void(*prnt)(const char *fmt, ...)) 720 { 721 struct witness *w; 722 723 KASSERT(!witness_cold, ("%s: witness_cold", __func__)); 724 witness_levelall(); 725 726 /* Clear all the displayed flags. */ 727 STAILQ_FOREACH(w, &w_all, w_list) { 728 w->w_displayed = 0; 729 } 730 731 /* 732 * First, handle sleep locks which have been acquired at least 733 * once. 734 */ 735 prnt("Sleep locks:\n"); 736 witness_display_list(prnt, &w_sleep); 737 738 /* 739 * Now do spin locks which have been acquired at least once. 740 */ 741 prnt("\nSpin locks:\n"); 742 witness_display_list(prnt, &w_spin); 743 744 /* 745 * Finally, any locks which have not been acquired yet. 746 */ 747 prnt("\nLocks which were never acquired:\n"); 748 STAILQ_FOREACH(w, &w_all, w_list) { 749 if (w->w_file != NULL || w->w_refcount == 0) 750 continue; 751 prnt("%s\n", w->w_name); 752 } 753 } 754 #endif /* DDB */ 755 756 /* Trim useless garbage from filenames. */ 757 static const char * 758 fixup_filename(const char *file) 759 { 760 761 if (file == NULL) 762 return (NULL); 763 while (strncmp(file, "../", 3) == 0) 764 file += 3; 765 return (file); 766 } 767 768 int 769 witness_defineorder(struct lock_object *lock1, struct lock_object *lock2) 770 { 771 772 if (witness_watch == 0 || panicstr != NULL) 773 return (0); 774 775 /* Require locks that witness knows about. */ 776 if (lock1 == NULL || lock1->lo_witness == NULL || lock2 == NULL || 777 lock2->lo_witness == NULL) 778 return (EINVAL); 779 780 MPASS(!mtx_owned(&w_mtx)); 781 mtx_lock_spin(&w_mtx); 782 783 /* 784 * If we already have either an explicit or implied lock order that 785 * is the other way around, then return an error. 786 */ 787 if (isitmydescendant(lock2->lo_witness, lock1->lo_witness)) { 788 mtx_unlock_spin(&w_mtx); 789 return (EDOOFUS); 790 } 791 792 /* Try to add the new order. */ 793 CTR3(KTR_WITNESS, "%s: adding %s as a child of %s", __func__, 794 lock2->lo_type, lock1->lo_type); 795 if (!itismychild(lock1->lo_witness, lock2->lo_witness)) 796 return (ENOMEM); 797 mtx_unlock_spin(&w_mtx); 798 return (0); 799 } 800 801 void 802 witness_checkorder(struct lock_object *lock, int flags, const char *file, 803 int line) 804 { 805 struct lock_list_entry **lock_list, *lle; 806 struct lock_instance *lock1, *lock2; 807 struct lock_class *class; 808 struct witness *w, *w1; 809 struct thread *td; 810 int i, j; 811 812 if (witness_cold || witness_watch == 0 || lock->lo_witness == NULL || 813 panicstr != NULL) 814 return; 815 816 /* 817 * Try locks do not block if they fail to acquire the lock, thus 818 * there is no danger of deadlocks or of switching while holding a 819 * spin lock if we acquire a lock via a try operation. This 820 * function shouldn't even be called for try locks, so panic if 821 * that happens. 822 */ 823 if (flags & LOP_TRYLOCK) 824 panic("%s should not be called for try lock operations", 825 __func__); 826 827 w = lock->lo_witness; 828 class = LOCK_CLASS(lock); 829 td = curthread; 830 file = fixup_filename(file); 831 832 if (class->lc_flags & LC_SLEEPLOCK) { 833 /* 834 * Since spin locks include a critical section, this check 835 * implicitly enforces a lock order of all sleep locks before 836 * all spin locks. 837 */ 838 if (td->td_critnest != 0 && !kdb_active) 839 panic("blockable sleep lock (%s) %s @ %s:%d", 840 class->lc_name, lock->lo_name, file, line); 841 842 /* 843 * If this is the first lock acquired then just return as 844 * no order checking is needed. 845 */ 846 if (td->td_sleeplocks == NULL) 847 return; 848 lock_list = &td->td_sleeplocks; 849 } else { 850 /* 851 * If this is the first lock, just return as no order 852 * checking is needed. We check this in both if clauses 853 * here as unifying the check would require us to use a 854 * critical section to ensure we don't migrate while doing 855 * the check. Note that if this is not the first lock, we 856 * are already in a critical section and are safe for the 857 * rest of the check. 858 */ 859 if (PCPU_GET(spinlocks) == NULL) 860 return; 861 lock_list = PCPU_PTR(spinlocks); 862 } 863 864 /* 865 * Check to see if we are recursing on a lock we already own. If 866 * so, make sure that we don't mismatch exclusive and shared lock 867 * acquires. 868 */ 869 lock1 = find_instance(*lock_list, lock); 870 if (lock1 != NULL) { 871 if ((lock1->li_flags & LI_EXCLUSIVE) != 0 && 872 (flags & LOP_EXCLUSIVE) == 0) { 873 printf("shared lock of (%s) %s @ %s:%d\n", 874 class->lc_name, lock->lo_name, file, line); 875 printf("while exclusively locked from %s:%d\n", 876 lock1->li_file, lock1->li_line); 877 panic("share->excl"); 878 } 879 if ((lock1->li_flags & LI_EXCLUSIVE) == 0 && 880 (flags & LOP_EXCLUSIVE) != 0) { 881 printf("exclusive lock of (%s) %s @ %s:%d\n", 882 class->lc_name, lock->lo_name, file, line); 883 printf("while share locked from %s:%d\n", 884 lock1->li_file, lock1->li_line); 885 panic("excl->share"); 886 } 887 return; 888 } 889 890 /* 891 * Try locks do not block if they fail to acquire the lock, thus 892 * there is no danger of deadlocks or of switching while holding a 893 * spin lock if we acquire a lock via a try operation. 894 */ 895 if (flags & LOP_TRYLOCK) 896 return; 897 898 /* 899 * Check for duplicate locks of the same type. Note that we only 900 * have to check for this on the last lock we just acquired. Any 901 * other cases will be caught as lock order violations. 902 */ 903 lock1 = &(*lock_list)->ll_children[(*lock_list)->ll_count - 1]; 904 w1 = lock1->li_lock->lo_witness; 905 if (w1 == w) { 906 if (w->w_same_squawked || (lock->lo_flags & LO_DUPOK) || 907 (flags & LOP_DUPOK)) 908 return; 909 w->w_same_squawked = 1; 910 printf("acquiring duplicate lock of same type: \"%s\"\n", 911 lock->lo_type); 912 printf(" 1st %s @ %s:%d\n", lock1->li_lock->lo_name, 913 lock1->li_file, lock1->li_line); 914 printf(" 2nd %s @ %s:%d\n", lock->lo_name, file, line); 915 #ifdef KDB 916 goto debugger; 917 #else 918 return; 919 #endif 920 } 921 MPASS(!mtx_owned(&w_mtx)); 922 mtx_lock_spin(&w_mtx); 923 /* 924 * If we know that the the lock we are acquiring comes after 925 * the lock we most recently acquired in the lock order tree, 926 * then there is no need for any further checks. 927 */ 928 if (isitmychild(w1, w)) { 929 mtx_unlock_spin(&w_mtx); 930 return; 931 } 932 for (j = 0, lle = *lock_list; lle != NULL; lle = lle->ll_next) { 933 for (i = lle->ll_count - 1; i >= 0; i--, j++) { 934 935 MPASS(j < WITNESS_COUNT); 936 lock1 = &lle->ll_children[i]; 937 w1 = lock1->li_lock->lo_witness; 938 939 /* 940 * If this lock doesn't undergo witness checking, 941 * then skip it. 942 */ 943 if (w1 == NULL) { 944 KASSERT((lock1->li_lock->lo_flags & LO_WITNESS) == 0, 945 ("lock missing witness structure")); 946 continue; 947 } 948 /* 949 * If we are locking Giant and this is a sleepable 950 * lock, then skip it. 951 */ 952 if ((lock1->li_lock->lo_flags & LO_SLEEPABLE) != 0 && 953 lock == &Giant.mtx_object) 954 continue; 955 /* 956 * If we are locking a sleepable lock and this lock 957 * is Giant, then skip it. 958 */ 959 if ((lock->lo_flags & LO_SLEEPABLE) != 0 && 960 lock1->li_lock == &Giant.mtx_object) 961 continue; 962 /* 963 * If we are locking a sleepable lock and this lock 964 * isn't sleepable, we want to treat it as a lock 965 * order violation to enfore a general lock order of 966 * sleepable locks before non-sleepable locks. 967 */ 968 if (((lock->lo_flags & LO_SLEEPABLE) != 0 && 969 (lock1->li_lock->lo_flags & LO_SLEEPABLE) == 0)) 970 goto reversal; 971 /* 972 * If we are locking Giant and this is a non-sleepable 973 * lock, then treat it as a reversal. 974 */ 975 if ((lock1->li_lock->lo_flags & LO_SLEEPABLE) == 0 && 976 lock == &Giant.mtx_object) 977 goto reversal; 978 /* 979 * Check the lock order hierarchy for a reveresal. 980 */ 981 if (!isitmydescendant(w, w1)) 982 continue; 983 reversal: 984 /* 985 * We have a lock order violation, check to see if it 986 * is allowed or has already been yelled about. 987 */ 988 mtx_unlock_spin(&w_mtx); 989 #ifdef BLESSING 990 /* 991 * If the lock order is blessed, just bail. We don't 992 * look for other lock order violations though, which 993 * may be a bug. 994 */ 995 if (blessed(w, w1)) 996 return; 997 #endif 998 if (lock1->li_lock == &Giant.mtx_object) { 999 if (w1->w_Giant_squawked) 1000 return; 1001 else 1002 w1->w_Giant_squawked = 1; 1003 } else { 1004 if (w1->w_other_squawked) 1005 return; 1006 else 1007 w1->w_other_squawked = 1; 1008 } 1009 /* 1010 * Ok, yell about it. 1011 */ 1012 if (((lock->lo_flags & LO_SLEEPABLE) != 0 && 1013 (lock1->li_lock->lo_flags & LO_SLEEPABLE) == 0)) 1014 printf( 1015 "lock order reversal: (sleepable after non-sleepable)\n"); 1016 else if ((lock1->li_lock->lo_flags & LO_SLEEPABLE) == 0 1017 && lock == &Giant.mtx_object) 1018 printf( 1019 "lock order reversal: (Giant after non-sleepable)\n"); 1020 else 1021 printf("lock order reversal:\n"); 1022 /* 1023 * Try to locate an earlier lock with 1024 * witness w in our list. 1025 */ 1026 do { 1027 lock2 = &lle->ll_children[i]; 1028 MPASS(lock2->li_lock != NULL); 1029 if (lock2->li_lock->lo_witness == w) 1030 break; 1031 if (i == 0 && lle->ll_next != NULL) { 1032 lle = lle->ll_next; 1033 i = lle->ll_count - 1; 1034 MPASS(i >= 0 && i < LOCK_NCHILDREN); 1035 } else 1036 i--; 1037 } while (i >= 0); 1038 if (i < 0) { 1039 printf(" 1st %p %s (%s) @ %s:%d\n", 1040 lock1->li_lock, lock1->li_lock->lo_name, 1041 lock1->li_lock->lo_type, lock1->li_file, 1042 lock1->li_line); 1043 printf(" 2nd %p %s (%s) @ %s:%d\n", lock, 1044 lock->lo_name, lock->lo_type, file, line); 1045 } else { 1046 printf(" 1st %p %s (%s) @ %s:%d\n", 1047 lock2->li_lock, lock2->li_lock->lo_name, 1048 lock2->li_lock->lo_type, lock2->li_file, 1049 lock2->li_line); 1050 printf(" 2nd %p %s (%s) @ %s:%d\n", 1051 lock1->li_lock, lock1->li_lock->lo_name, 1052 lock1->li_lock->lo_type, lock1->li_file, 1053 lock1->li_line); 1054 printf(" 3rd %p %s (%s) @ %s:%d\n", lock, 1055 lock->lo_name, lock->lo_type, file, line); 1056 } 1057 #ifdef KDB 1058 goto debugger; 1059 #else 1060 return; 1061 #endif 1062 } 1063 } 1064 lock1 = &(*lock_list)->ll_children[(*lock_list)->ll_count - 1]; 1065 /* 1066 * If requested, build a new lock order. However, don't build a new 1067 * relationship between a sleepable lock and Giant if it is in the 1068 * wrong direction. The correct lock order is that sleepable locks 1069 * always come before Giant. 1070 */ 1071 if (flags & LOP_NEWORDER && 1072 !(lock1->li_lock == &Giant.mtx_object && 1073 (lock->lo_flags & LO_SLEEPABLE) != 0)) { 1074 CTR3(KTR_WITNESS, "%s: adding %s as a child of %s", __func__, 1075 lock->lo_type, lock1->li_lock->lo_type); 1076 if (!itismychild(lock1->li_lock->lo_witness, w)) 1077 /* Witness is dead. */ 1078 return; 1079 } 1080 mtx_unlock_spin(&w_mtx); 1081 return; 1082 1083 #ifdef KDB 1084 debugger: 1085 if (witness_trace) 1086 kdb_backtrace(); 1087 if (witness_kdb) 1088 kdb_enter(__func__); 1089 #endif 1090 } 1091 1092 void 1093 witness_lock(struct lock_object *lock, int flags, const char *file, int line) 1094 { 1095 struct lock_list_entry **lock_list, *lle; 1096 struct lock_instance *instance; 1097 struct witness *w; 1098 struct thread *td; 1099 1100 if (witness_cold || witness_watch == 0 || lock->lo_witness == NULL || 1101 panicstr != NULL) 1102 return; 1103 w = lock->lo_witness; 1104 td = curthread; 1105 file = fixup_filename(file); 1106 1107 /* Determine lock list for this lock. */ 1108 if (LOCK_CLASS(lock)->lc_flags & LC_SLEEPLOCK) 1109 lock_list = &td->td_sleeplocks; 1110 else 1111 lock_list = PCPU_PTR(spinlocks); 1112 1113 /* Check to see if we are recursing on a lock we already own. */ 1114 instance = find_instance(*lock_list, lock); 1115 if (instance != NULL) { 1116 instance->li_flags++; 1117 CTR4(KTR_WITNESS, "%s: pid %d recursed on %s r=%d", __func__, 1118 td->td_proc->p_pid, lock->lo_name, 1119 instance->li_flags & LI_RECURSEMASK); 1120 instance->li_file = file; 1121 instance->li_line = line; 1122 return; 1123 } 1124 1125 /* Update per-witness last file and line acquire. */ 1126 w->w_file = file; 1127 w->w_line = line; 1128 1129 /* Find the next open lock instance in the list and fill it. */ 1130 lle = *lock_list; 1131 if (lle == NULL || lle->ll_count == LOCK_NCHILDREN) { 1132 lle = witness_lock_list_get(); 1133 if (lle == NULL) 1134 return; 1135 lle->ll_next = *lock_list; 1136 CTR3(KTR_WITNESS, "%s: pid %d added lle %p", __func__, 1137 td->td_proc->p_pid, lle); 1138 *lock_list = lle; 1139 } 1140 instance = &lle->ll_children[lle->ll_count++]; 1141 instance->li_lock = lock; 1142 instance->li_line = line; 1143 instance->li_file = file; 1144 if ((flags & LOP_EXCLUSIVE) != 0) 1145 instance->li_flags = LI_EXCLUSIVE; 1146 else 1147 instance->li_flags = 0; 1148 CTR4(KTR_WITNESS, "%s: pid %d added %s as lle[%d]", __func__, 1149 td->td_proc->p_pid, lock->lo_name, lle->ll_count - 1); 1150 } 1151 1152 void 1153 witness_upgrade(struct lock_object *lock, int flags, const char *file, int line) 1154 { 1155 struct lock_instance *instance; 1156 struct lock_class *class; 1157 1158 KASSERT(!witness_cold, ("%s: witness_cold", __func__)); 1159 if (lock->lo_witness == NULL || witness_watch == 0 || panicstr != NULL) 1160 return; 1161 class = LOCK_CLASS(lock); 1162 file = fixup_filename(file); 1163 if ((lock->lo_flags & LO_UPGRADABLE) == 0) 1164 panic("upgrade of non-upgradable lock (%s) %s @ %s:%d", 1165 class->lc_name, lock->lo_name, file, line); 1166 if ((flags & LOP_TRYLOCK) == 0) 1167 panic("non-try upgrade of lock (%s) %s @ %s:%d", class->lc_name, 1168 lock->lo_name, file, line); 1169 if ((class->lc_flags & LC_SLEEPLOCK) == 0) 1170 panic("upgrade of non-sleep lock (%s) %s @ %s:%d", 1171 class->lc_name, lock->lo_name, file, line); 1172 instance = find_instance(curthread->td_sleeplocks, lock); 1173 if (instance == NULL) 1174 panic("upgrade of unlocked lock (%s) %s @ %s:%d", 1175 class->lc_name, lock->lo_name, file, line); 1176 if ((instance->li_flags & LI_EXCLUSIVE) != 0) 1177 panic("upgrade of exclusive lock (%s) %s @ %s:%d", 1178 class->lc_name, lock->lo_name, file, line); 1179 if ((instance->li_flags & LI_RECURSEMASK) != 0) 1180 panic("upgrade of recursed lock (%s) %s r=%d @ %s:%d", 1181 class->lc_name, lock->lo_name, 1182 instance->li_flags & LI_RECURSEMASK, file, line); 1183 instance->li_flags |= LI_EXCLUSIVE; 1184 } 1185 1186 void 1187 witness_downgrade(struct lock_object *lock, int flags, const char *file, 1188 int line) 1189 { 1190 struct lock_instance *instance; 1191 struct lock_class *class; 1192 1193 KASSERT(!witness_cold, ("%s: witness_cold", __func__)); 1194 if (lock->lo_witness == NULL || witness_watch == 0 || panicstr != NULL) 1195 return; 1196 class = LOCK_CLASS(lock); 1197 file = fixup_filename(file); 1198 if ((lock->lo_flags & LO_UPGRADABLE) == 0) 1199 panic("downgrade of non-upgradable lock (%s) %s @ %s:%d", 1200 class->lc_name, lock->lo_name, file, line); 1201 if ((class->lc_flags & LC_SLEEPLOCK) == 0) 1202 panic("downgrade of non-sleep lock (%s) %s @ %s:%d", 1203 class->lc_name, lock->lo_name, file, line); 1204 instance = find_instance(curthread->td_sleeplocks, lock); 1205 if (instance == NULL) 1206 panic("downgrade of unlocked lock (%s) %s @ %s:%d", 1207 class->lc_name, lock->lo_name, file, line); 1208 if ((instance->li_flags & LI_EXCLUSIVE) == 0) 1209 panic("downgrade of shared lock (%s) %s @ %s:%d", 1210 class->lc_name, lock->lo_name, file, line); 1211 if ((instance->li_flags & LI_RECURSEMASK) != 0) 1212 panic("downgrade of recursed lock (%s) %s r=%d @ %s:%d", 1213 class->lc_name, lock->lo_name, 1214 instance->li_flags & LI_RECURSEMASK, file, line); 1215 instance->li_flags &= ~LI_EXCLUSIVE; 1216 } 1217 1218 void 1219 witness_unlock(struct lock_object *lock, int flags, const char *file, int line) 1220 { 1221 struct lock_list_entry **lock_list, *lle; 1222 struct lock_instance *instance; 1223 struct lock_class *class; 1224 struct thread *td; 1225 register_t s; 1226 int i, j; 1227 1228 if (witness_cold || witness_watch == 0 || lock->lo_witness == NULL || 1229 panicstr != NULL) 1230 return; 1231 td = curthread; 1232 class = LOCK_CLASS(lock); 1233 file = fixup_filename(file); 1234 1235 /* Find lock instance associated with this lock. */ 1236 if (class->lc_flags & LC_SLEEPLOCK) 1237 lock_list = &td->td_sleeplocks; 1238 else 1239 lock_list = PCPU_PTR(spinlocks); 1240 for (; *lock_list != NULL; lock_list = &(*lock_list)->ll_next) 1241 for (i = 0; i < (*lock_list)->ll_count; i++) { 1242 instance = &(*lock_list)->ll_children[i]; 1243 if (instance->li_lock == lock) 1244 goto found; 1245 } 1246 panic("lock (%s) %s not locked @ %s:%d", class->lc_name, lock->lo_name, 1247 file, line); 1248 found: 1249 1250 /* First, check for shared/exclusive mismatches. */ 1251 if ((instance->li_flags & LI_EXCLUSIVE) != 0 && 1252 (flags & LOP_EXCLUSIVE) == 0) { 1253 printf("shared unlock of (%s) %s @ %s:%d\n", class->lc_name, 1254 lock->lo_name, file, line); 1255 printf("while exclusively locked from %s:%d\n", 1256 instance->li_file, instance->li_line); 1257 panic("excl->ushare"); 1258 } 1259 if ((instance->li_flags & LI_EXCLUSIVE) == 0 && 1260 (flags & LOP_EXCLUSIVE) != 0) { 1261 printf("exclusive unlock of (%s) %s @ %s:%d\n", class->lc_name, 1262 lock->lo_name, file, line); 1263 printf("while share locked from %s:%d\n", instance->li_file, 1264 instance->li_line); 1265 panic("share->uexcl"); 1266 } 1267 1268 /* If we are recursed, unrecurse. */ 1269 if ((instance->li_flags & LI_RECURSEMASK) > 0) { 1270 CTR4(KTR_WITNESS, "%s: pid %d unrecursed on %s r=%d", __func__, 1271 td->td_proc->p_pid, instance->li_lock->lo_name, 1272 instance->li_flags); 1273 instance->li_flags--; 1274 return; 1275 } 1276 1277 /* Otherwise, remove this item from the list. */ 1278 s = intr_disable(); 1279 CTR4(KTR_WITNESS, "%s: pid %d removed %s from lle[%d]", __func__, 1280 td->td_proc->p_pid, instance->li_lock->lo_name, 1281 (*lock_list)->ll_count - 1); 1282 for (j = i; j < (*lock_list)->ll_count - 1; j++) 1283 (*lock_list)->ll_children[j] = 1284 (*lock_list)->ll_children[j + 1]; 1285 (*lock_list)->ll_count--; 1286 intr_restore(s); 1287 1288 /* If this lock list entry is now empty, free it. */ 1289 if ((*lock_list)->ll_count == 0) { 1290 lle = *lock_list; 1291 *lock_list = lle->ll_next; 1292 CTR3(KTR_WITNESS, "%s: pid %d removed lle %p", __func__, 1293 td->td_proc->p_pid, lle); 1294 witness_lock_list_free(lle); 1295 } 1296 } 1297 1298 /* 1299 * Warn if any locks other than 'lock' are held. Flags can be passed in to 1300 * exempt Giant and sleepable locks from the checks as well. If any 1301 * non-exempt locks are held, then a supplied message is printed to the 1302 * console along with a list of the offending locks. If indicated in the 1303 * flags then a failure results in a panic as well. 1304 */ 1305 int 1306 witness_warn(int flags, struct lock_object *lock, const char *fmt, ...) 1307 { 1308 struct lock_list_entry *lle; 1309 struct lock_instance *lock1; 1310 struct thread *td; 1311 va_list ap; 1312 int i, n; 1313 1314 if (witness_cold || witness_watch == 0 || panicstr != NULL) 1315 return (0); 1316 n = 0; 1317 td = curthread; 1318 for (lle = td->td_sleeplocks; lle != NULL; lle = lle->ll_next) 1319 for (i = lle->ll_count - 1; i >= 0; i--) { 1320 lock1 = &lle->ll_children[i]; 1321 if (lock1->li_lock == lock) 1322 continue; 1323 if (flags & WARN_GIANTOK && 1324 lock1->li_lock == &Giant.mtx_object) 1325 continue; 1326 if (flags & WARN_SLEEPOK && 1327 (lock1->li_lock->lo_flags & LO_SLEEPABLE) != 0) 1328 continue; 1329 if (n == 0) { 1330 va_start(ap, fmt); 1331 vprintf(fmt, ap); 1332 va_end(ap); 1333 printf(" with the following"); 1334 if (flags & WARN_SLEEPOK) 1335 printf(" non-sleepable"); 1336 printf(" locks held:\n"); 1337 } 1338 n++; 1339 witness_list_lock(lock1); 1340 } 1341 if (PCPU_GET(spinlocks) != NULL) { 1342 /* 1343 * Since we already hold a spinlock preemption is 1344 * already blocked. 1345 */ 1346 if (n == 0) { 1347 va_start(ap, fmt); 1348 vprintf(fmt, ap); 1349 va_end(ap); 1350 printf(" with the following"); 1351 if (flags & WARN_SLEEPOK) 1352 printf(" non-sleepable"); 1353 printf(" locks held:\n"); 1354 } 1355 n += witness_list_locks(PCPU_PTR(spinlocks)); 1356 } 1357 if (flags & WARN_PANIC && n) 1358 panic("witness_warn"); 1359 #ifdef KDB 1360 else if (witness_kdb && n) 1361 kdb_enter(__func__); 1362 else if (witness_trace && n) 1363 kdb_backtrace(); 1364 #endif 1365 return (n); 1366 } 1367 1368 const char * 1369 witness_file(struct lock_object *lock) 1370 { 1371 struct witness *w; 1372 1373 if (witness_cold || witness_watch == 0 || lock->lo_witness == NULL) 1374 return ("?"); 1375 w = lock->lo_witness; 1376 return (w->w_file); 1377 } 1378 1379 int 1380 witness_line(struct lock_object *lock) 1381 { 1382 struct witness *w; 1383 1384 if (witness_cold || witness_watch == 0 || lock->lo_witness == NULL) 1385 return (0); 1386 w = lock->lo_witness; 1387 return (w->w_line); 1388 } 1389 1390 static struct witness * 1391 enroll(const char *description, struct lock_class *lock_class) 1392 { 1393 struct witness *w; 1394 1395 if (witness_watch == 0 || panicstr != NULL) 1396 return (NULL); 1397 if ((lock_class->lc_flags & LC_SPINLOCK) && witness_skipspin) 1398 return (NULL); 1399 mtx_lock_spin(&w_mtx); 1400 STAILQ_FOREACH(w, &w_all, w_list) { 1401 if (w->w_name == description || (w->w_refcount > 0 && 1402 strcmp(description, w->w_name) == 0)) { 1403 w->w_refcount++; 1404 mtx_unlock_spin(&w_mtx); 1405 if (lock_class != w->w_class) 1406 panic( 1407 "lock (%s) %s does not match earlier (%s) lock", 1408 description, lock_class->lc_name, 1409 w->w_class->lc_name); 1410 return (w); 1411 } 1412 } 1413 if ((w = witness_get()) == NULL) 1414 goto out; 1415 w->w_name = description; 1416 w->w_class = lock_class; 1417 w->w_refcount = 1; 1418 STAILQ_INSERT_HEAD(&w_all, w, w_list); 1419 if (lock_class->lc_flags & LC_SPINLOCK) { 1420 STAILQ_INSERT_HEAD(&w_spin, w, w_typelist); 1421 w_spin_cnt++; 1422 } else if (lock_class->lc_flags & LC_SLEEPLOCK) { 1423 STAILQ_INSERT_HEAD(&w_sleep, w, w_typelist); 1424 w_sleep_cnt++; 1425 } else { 1426 mtx_unlock_spin(&w_mtx); 1427 panic("lock class %s is not sleep or spin", 1428 lock_class->lc_name); 1429 } 1430 mtx_unlock_spin(&w_mtx); 1431 out: 1432 /* 1433 * We issue a warning for any spin locks not defined in the static 1434 * order list as a way to discourage their use (folks should really 1435 * be using non-spin mutexes most of the time). However, several 1436 * 3rd part device drivers use spin locks because that is all they 1437 * have available on Windows and Linux and they think that normal 1438 * mutexes are insufficient. 1439 */ 1440 if ((lock_class->lc_flags & LC_SPINLOCK) && witness_spin_warn) 1441 printf("WITNESS: spin lock %s not in order list\n", 1442 description); 1443 return (w); 1444 } 1445 1446 /* Don't let the door bang you on the way out... */ 1447 static int 1448 depart(struct witness *w) 1449 { 1450 struct witness_child_list_entry *wcl, *nwcl; 1451 struct witness_list *list; 1452 struct witness *parent; 1453 1454 MPASS(w->w_refcount == 0); 1455 if (w->w_class->lc_flags & LC_SLEEPLOCK) { 1456 list = &w_sleep; 1457 w_sleep_cnt--; 1458 } else { 1459 list = &w_spin; 1460 w_spin_cnt--; 1461 } 1462 /* 1463 * First, we run through the entire tree looking for any 1464 * witnesses that the outgoing witness is a child of. For 1465 * each parent that we find, we reparent all the direct 1466 * children of the outgoing witness to its parent. 1467 */ 1468 STAILQ_FOREACH(parent, list, w_typelist) { 1469 if (!isitmychild(parent, w)) 1470 continue; 1471 removechild(parent, w); 1472 } 1473 1474 /* 1475 * Now we go through and free up the child list of the 1476 * outgoing witness. 1477 */ 1478 for (wcl = w->w_children; wcl != NULL; wcl = nwcl) { 1479 nwcl = wcl->wcl_next; 1480 w_child_cnt--; 1481 witness_child_free(wcl); 1482 } 1483 1484 /* 1485 * Detach from various lists and free. 1486 */ 1487 STAILQ_REMOVE(list, w, witness, w_typelist); 1488 STAILQ_REMOVE(&w_all, w, witness, w_list); 1489 witness_free(w); 1490 1491 return (1); 1492 } 1493 1494 /* 1495 * Add "child" as a direct child of "parent". Returns false if 1496 * we fail due to out of memory. 1497 */ 1498 static int 1499 insertchild(struct witness *parent, struct witness *child) 1500 { 1501 struct witness_child_list_entry **wcl; 1502 1503 MPASS(child != NULL && parent != NULL); 1504 1505 /* 1506 * Insert "child" after "parent" 1507 */ 1508 wcl = &parent->w_children; 1509 while (*wcl != NULL && (*wcl)->wcl_count == WITNESS_NCHILDREN) 1510 wcl = &(*wcl)->wcl_next; 1511 if (*wcl == NULL) { 1512 *wcl = witness_child_get(); 1513 if (*wcl == NULL) 1514 return (0); 1515 w_child_cnt++; 1516 } 1517 (*wcl)->wcl_children[(*wcl)->wcl_count++] = child; 1518 1519 return (1); 1520 } 1521 1522 1523 static int 1524 itismychild(struct witness *parent, struct witness *child) 1525 { 1526 struct witness_list *list; 1527 1528 MPASS(child != NULL && parent != NULL); 1529 if ((parent->w_class->lc_flags & (LC_SLEEPLOCK | LC_SPINLOCK)) != 1530 (child->w_class->lc_flags & (LC_SLEEPLOCK | LC_SPINLOCK))) 1531 panic( 1532 "%s: parent (%s) and child (%s) are not the same lock type", 1533 __func__, parent->w_class->lc_name, 1534 child->w_class->lc_name); 1535 1536 if (!insertchild(parent, child)) 1537 return (0); 1538 1539 if (parent->w_class->lc_flags & LC_SLEEPLOCK) 1540 list = &w_sleep; 1541 else 1542 list = &w_spin; 1543 return (1); 1544 } 1545 1546 static void 1547 removechild(struct witness *parent, struct witness *child) 1548 { 1549 struct witness_child_list_entry **wcl, *wcl1; 1550 int i; 1551 1552 for (wcl = &parent->w_children; *wcl != NULL; wcl = &(*wcl)->wcl_next) 1553 for (i = 0; i < (*wcl)->wcl_count; i++) 1554 if ((*wcl)->wcl_children[i] == child) 1555 goto found; 1556 return; 1557 found: 1558 (*wcl)->wcl_count--; 1559 if ((*wcl)->wcl_count > i) 1560 (*wcl)->wcl_children[i] = 1561 (*wcl)->wcl_children[(*wcl)->wcl_count]; 1562 MPASS((*wcl)->wcl_children[i] != NULL); 1563 if ((*wcl)->wcl_count != 0) 1564 return; 1565 wcl1 = *wcl; 1566 *wcl = wcl1->wcl_next; 1567 w_child_cnt--; 1568 witness_child_free(wcl1); 1569 } 1570 1571 static int 1572 isitmychild(struct witness *parent, struct witness *child) 1573 { 1574 struct witness_child_list_entry *wcl; 1575 int i; 1576 1577 for (wcl = parent->w_children; wcl != NULL; wcl = wcl->wcl_next) { 1578 for (i = 0; i < wcl->wcl_count; i++) { 1579 if (wcl->wcl_children[i] == child) 1580 return (1); 1581 } 1582 } 1583 return (0); 1584 } 1585 1586 static int 1587 isitmydescendant(struct witness *parent, struct witness *child) 1588 { 1589 struct witness_child_list_entry *wcl; 1590 int i, j; 1591 1592 if (isitmychild(parent, child)) 1593 return (1); 1594 j = 0; 1595 for (wcl = parent->w_children; wcl != NULL; wcl = wcl->wcl_next) { 1596 MPASS(j < 1000); 1597 for (i = 0; i < wcl->wcl_count; i++) { 1598 if (isitmydescendant(wcl->wcl_children[i], child)) 1599 return (1); 1600 } 1601 j++; 1602 } 1603 return (0); 1604 } 1605 1606 #ifdef BLESSING 1607 static int 1608 blessed(struct witness *w1, struct witness *w2) 1609 { 1610 int i; 1611 struct witness_blessed *b; 1612 1613 for (i = 0; i < blessed_count; i++) { 1614 b = &blessed_list[i]; 1615 if (strcmp(w1->w_name, b->b_lock1) == 0) { 1616 if (strcmp(w2->w_name, b->b_lock2) == 0) 1617 return (1); 1618 continue; 1619 } 1620 if (strcmp(w1->w_name, b->b_lock2) == 0) 1621 if (strcmp(w2->w_name, b->b_lock1) == 0) 1622 return (1); 1623 } 1624 return (0); 1625 } 1626 #endif 1627 1628 static struct witness * 1629 witness_get(void) 1630 { 1631 struct witness *w; 1632 1633 if (witness_watch == 0) { 1634 mtx_unlock_spin(&w_mtx); 1635 return (NULL); 1636 } 1637 if (STAILQ_EMPTY(&w_free)) { 1638 witness_watch = 0; 1639 mtx_unlock_spin(&w_mtx); 1640 printf("%s: witness exhausted\n", __func__); 1641 return (NULL); 1642 } 1643 w = STAILQ_FIRST(&w_free); 1644 STAILQ_REMOVE_HEAD(&w_free, w_list); 1645 w_free_cnt--; 1646 bzero(w, sizeof(*w)); 1647 return (w); 1648 } 1649 1650 static void 1651 witness_free(struct witness *w) 1652 { 1653 1654 STAILQ_INSERT_HEAD(&w_free, w, w_list); 1655 w_free_cnt++; 1656 } 1657 1658 static struct witness_child_list_entry * 1659 witness_child_get(void) 1660 { 1661 struct witness_child_list_entry *wcl; 1662 1663 if (witness_watch == 0) { 1664 mtx_unlock_spin(&w_mtx); 1665 return (NULL); 1666 } 1667 wcl = w_child_free; 1668 if (wcl == NULL) { 1669 witness_watch = 0; 1670 mtx_unlock_spin(&w_mtx); 1671 printf("%s: witness exhausted\n", __func__); 1672 return (NULL); 1673 } 1674 w_child_free = wcl->wcl_next; 1675 w_child_free_cnt--; 1676 bzero(wcl, sizeof(*wcl)); 1677 return (wcl); 1678 } 1679 1680 static void 1681 witness_child_free(struct witness_child_list_entry *wcl) 1682 { 1683 1684 wcl->wcl_next = w_child_free; 1685 w_child_free = wcl; 1686 w_child_free_cnt++; 1687 } 1688 1689 static struct lock_list_entry * 1690 witness_lock_list_get(void) 1691 { 1692 struct lock_list_entry *lle; 1693 1694 if (witness_watch == 0) 1695 return (NULL); 1696 mtx_lock_spin(&w_mtx); 1697 lle = w_lock_list_free; 1698 if (lle == NULL) { 1699 witness_watch = 0; 1700 mtx_unlock_spin(&w_mtx); 1701 printf("%s: witness exhausted\n", __func__); 1702 return (NULL); 1703 } 1704 w_lock_list_free = lle->ll_next; 1705 mtx_unlock_spin(&w_mtx); 1706 bzero(lle, sizeof(*lle)); 1707 return (lle); 1708 } 1709 1710 static void 1711 witness_lock_list_free(struct lock_list_entry *lle) 1712 { 1713 1714 mtx_lock_spin(&w_mtx); 1715 lle->ll_next = w_lock_list_free; 1716 w_lock_list_free = lle; 1717 mtx_unlock_spin(&w_mtx); 1718 } 1719 1720 static struct lock_instance * 1721 find_instance(struct lock_list_entry *lock_list, struct lock_object *lock) 1722 { 1723 struct lock_list_entry *lle; 1724 struct lock_instance *instance; 1725 int i; 1726 1727 for (lle = lock_list; lle != NULL; lle = lle->ll_next) 1728 for (i = lle->ll_count - 1; i >= 0; i--) { 1729 instance = &lle->ll_children[i]; 1730 if (instance->li_lock == lock) 1731 return (instance); 1732 } 1733 return (NULL); 1734 } 1735 1736 static void 1737 witness_list_lock(struct lock_instance *instance) 1738 { 1739 struct lock_object *lock; 1740 1741 lock = instance->li_lock; 1742 printf("%s %s %s", (instance->li_flags & LI_EXCLUSIVE) != 0 ? 1743 "exclusive" : "shared", LOCK_CLASS(lock)->lc_name, lock->lo_name); 1744 if (lock->lo_type != lock->lo_name) 1745 printf(" (%s)", lock->lo_type); 1746 printf(" r = %d (%p) locked @ %s:%d\n", 1747 instance->li_flags & LI_RECURSEMASK, lock, instance->li_file, 1748 instance->li_line); 1749 } 1750 1751 #ifdef DDB 1752 static int 1753 witness_thread_has_locks(struct thread *td) 1754 { 1755 1756 return (td->td_sleeplocks != NULL); 1757 } 1758 1759 static int 1760 witness_proc_has_locks(struct proc *p) 1761 { 1762 struct thread *td; 1763 1764 FOREACH_THREAD_IN_PROC(p, td) { 1765 if (witness_thread_has_locks(td)) 1766 return (1); 1767 } 1768 return (0); 1769 } 1770 #endif 1771 1772 int 1773 witness_list_locks(struct lock_list_entry **lock_list) 1774 { 1775 struct lock_list_entry *lle; 1776 int i, nheld; 1777 1778 nheld = 0; 1779 for (lle = *lock_list; lle != NULL; lle = lle->ll_next) 1780 for (i = lle->ll_count - 1; i >= 0; i--) { 1781 witness_list_lock(&lle->ll_children[i]); 1782 nheld++; 1783 } 1784 return (nheld); 1785 } 1786 1787 /* 1788 * This is a bit risky at best. We call this function when we have timed 1789 * out acquiring a spin lock, and we assume that the other CPU is stuck 1790 * with this lock held. So, we go groveling around in the other CPU's 1791 * per-cpu data to try to find the lock instance for this spin lock to 1792 * see when it was last acquired. 1793 */ 1794 void 1795 witness_display_spinlock(struct lock_object *lock, struct thread *owner) 1796 { 1797 struct lock_instance *instance; 1798 struct pcpu *pc; 1799 1800 if (owner->td_critnest == 0 || owner->td_oncpu == NOCPU) 1801 return; 1802 pc = pcpu_find(owner->td_oncpu); 1803 instance = find_instance(pc->pc_spinlocks, lock); 1804 if (instance != NULL) 1805 witness_list_lock(instance); 1806 } 1807 1808 void 1809 witness_save(struct lock_object *lock, const char **filep, int *linep) 1810 { 1811 struct lock_list_entry *lock_list; 1812 struct lock_instance *instance; 1813 struct lock_class *class; 1814 1815 KASSERT(!witness_cold, ("%s: witness_cold", __func__)); 1816 if (lock->lo_witness == NULL || witness_watch == 0 || panicstr != NULL) 1817 return; 1818 class = LOCK_CLASS(lock); 1819 if (class->lc_flags & LC_SLEEPLOCK) 1820 lock_list = curthread->td_sleeplocks; 1821 else { 1822 if (witness_skipspin) 1823 return; 1824 lock_list = PCPU_GET(spinlocks); 1825 } 1826 instance = find_instance(lock_list, lock); 1827 if (instance == NULL) 1828 panic("%s: lock (%s) %s not locked", __func__, 1829 class->lc_name, lock->lo_name); 1830 *filep = instance->li_file; 1831 *linep = instance->li_line; 1832 } 1833 1834 void 1835 witness_restore(struct lock_object *lock, const char *file, int line) 1836 { 1837 struct lock_list_entry *lock_list; 1838 struct lock_instance *instance; 1839 struct lock_class *class; 1840 1841 KASSERT(!witness_cold, ("%s: witness_cold", __func__)); 1842 if (lock->lo_witness == NULL || witness_watch == 0 || panicstr != NULL) 1843 return; 1844 class = LOCK_CLASS(lock); 1845 if (class->lc_flags & LC_SLEEPLOCK) 1846 lock_list = curthread->td_sleeplocks; 1847 else { 1848 if (witness_skipspin) 1849 return; 1850 lock_list = PCPU_GET(spinlocks); 1851 } 1852 instance = find_instance(lock_list, lock); 1853 if (instance == NULL) 1854 panic("%s: lock (%s) %s not locked", __func__, 1855 class->lc_name, lock->lo_name); 1856 lock->lo_witness->w_file = file; 1857 lock->lo_witness->w_line = line; 1858 instance->li_file = file; 1859 instance->li_line = line; 1860 } 1861 1862 void 1863 witness_assert(struct lock_object *lock, int flags, const char *file, int line) 1864 { 1865 #ifdef INVARIANT_SUPPORT 1866 struct lock_instance *instance; 1867 struct lock_class *class; 1868 1869 if (lock->lo_witness == NULL || witness_watch == 0 || panicstr != NULL) 1870 return; 1871 class = LOCK_CLASS(lock); 1872 if ((class->lc_flags & LC_SLEEPLOCK) != 0) 1873 instance = find_instance(curthread->td_sleeplocks, lock); 1874 else if ((class->lc_flags & LC_SPINLOCK) != 0) 1875 instance = find_instance(PCPU_GET(spinlocks), lock); 1876 else { 1877 panic("Lock (%s) %s is not sleep or spin!", 1878 class->lc_name, lock->lo_name); 1879 } 1880 file = fixup_filename(file); 1881 switch (flags) { 1882 case LA_UNLOCKED: 1883 if (instance != NULL) 1884 panic("Lock (%s) %s locked @ %s:%d.", 1885 class->lc_name, lock->lo_name, file, line); 1886 break; 1887 case LA_LOCKED: 1888 case LA_LOCKED | LA_RECURSED: 1889 case LA_LOCKED | LA_NOTRECURSED: 1890 case LA_SLOCKED: 1891 case LA_SLOCKED | LA_RECURSED: 1892 case LA_SLOCKED | LA_NOTRECURSED: 1893 case LA_XLOCKED: 1894 case LA_XLOCKED | LA_RECURSED: 1895 case LA_XLOCKED | LA_NOTRECURSED: 1896 if (instance == NULL) { 1897 panic("Lock (%s) %s not locked @ %s:%d.", 1898 class->lc_name, lock->lo_name, file, line); 1899 break; 1900 } 1901 if ((flags & LA_XLOCKED) != 0 && 1902 (instance->li_flags & LI_EXCLUSIVE) == 0) 1903 panic("Lock (%s) %s not exclusively locked @ %s:%d.", 1904 class->lc_name, lock->lo_name, file, line); 1905 if ((flags & LA_SLOCKED) != 0 && 1906 (instance->li_flags & LI_EXCLUSIVE) != 0) 1907 panic("Lock (%s) %s exclusively locked @ %s:%d.", 1908 class->lc_name, lock->lo_name, file, line); 1909 if ((flags & LA_RECURSED) != 0 && 1910 (instance->li_flags & LI_RECURSEMASK) == 0) 1911 panic("Lock (%s) %s not recursed @ %s:%d.", 1912 class->lc_name, lock->lo_name, file, line); 1913 if ((flags & LA_NOTRECURSED) != 0 && 1914 (instance->li_flags & LI_RECURSEMASK) != 0) 1915 panic("Lock (%s) %s recursed @ %s:%d.", 1916 class->lc_name, lock->lo_name, file, line); 1917 break; 1918 default: 1919 panic("Invalid lock assertion at %s:%d.", file, line); 1920 1921 } 1922 #endif /* INVARIANT_SUPPORT */ 1923 } 1924 1925 #ifdef DDB 1926 static void 1927 witness_list(struct thread *td) 1928 { 1929 1930 KASSERT(!witness_cold, ("%s: witness_cold", __func__)); 1931 KASSERT(kdb_active, ("%s: not in the debugger", __func__)); 1932 1933 if (witness_watch == 0) 1934 return; 1935 1936 witness_list_locks(&td->td_sleeplocks); 1937 1938 /* 1939 * We only handle spinlocks if td == curthread. This is somewhat broken 1940 * if td is currently executing on some other CPU and holds spin locks 1941 * as we won't display those locks. If we had a MI way of getting 1942 * the per-cpu data for a given cpu then we could use 1943 * td->td_oncpu to get the list of spinlocks for this thread 1944 * and "fix" this. 1945 * 1946 * That still wouldn't really fix this unless we locked sched_lock 1947 * or stopped the other CPU to make sure it wasn't changing the list 1948 * out from under us. It is probably best to just not try to handle 1949 * threads on other CPU's for now. 1950 */ 1951 if (td == curthread && PCPU_GET(spinlocks) != NULL) 1952 witness_list_locks(PCPU_PTR(spinlocks)); 1953 } 1954 1955 DB_SHOW_COMMAND(locks, db_witness_list) 1956 { 1957 struct thread *td; 1958 pid_t pid; 1959 struct proc *p; 1960 1961 if (have_addr) { 1962 pid = (addr % 16) + ((addr >> 4) % 16) * 10 + 1963 ((addr >> 8) % 16) * 100 + ((addr >> 12) % 16) * 1000 + 1964 ((addr >> 16) % 16) * 10000; 1965 /* sx_slock(&allproc_lock); */ 1966 FOREACH_PROC_IN_SYSTEM(p) { 1967 if (p->p_pid == pid) 1968 break; 1969 } 1970 /* sx_sunlock(&allproc_lock); */ 1971 if (p == NULL) { 1972 db_printf("pid %d not found\n", pid); 1973 return; 1974 } 1975 FOREACH_THREAD_IN_PROC(p, td) { 1976 witness_list(td); 1977 } 1978 } else { 1979 td = curthread; 1980 witness_list(td); 1981 } 1982 } 1983 1984 DB_SHOW_COMMAND(alllocks, db_witness_list_all) 1985 { 1986 struct thread *td; 1987 struct proc *p; 1988 1989 /* 1990 * It would be nice to list only threads and processes that actually 1991 * held sleep locks, but that information is currently not exported 1992 * by WITNESS. 1993 */ 1994 FOREACH_PROC_IN_SYSTEM(p) { 1995 if (!witness_proc_has_locks(p)) 1996 continue; 1997 FOREACH_THREAD_IN_PROC(p, td) { 1998 if (!witness_thread_has_locks(td)) 1999 continue; 2000 db_printf("Process %d (%s) thread %p (%d)\n", p->p_pid, 2001 p->p_comm, td, td->td_tid); 2002 witness_list(td); 2003 } 2004 } 2005 } 2006 2007 DB_SHOW_COMMAND(witness, db_witness_display) 2008 { 2009 2010 witness_display(db_printf); 2011 } 2012 #endif 2013