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 * $FreeBSD$ 31 */ 32 33 /* 34 * Implementation of the `witness' lock verifier. Originally implemented for 35 * mutexes in BSD/OS. Extended to handle generic lock objects and lock 36 * classes in FreeBSD. 37 */ 38 39 /* 40 * Main Entry: witness 41 * Pronunciation: 'wit-n&s 42 * Function: noun 43 * Etymology: Middle English witnesse, from Old English witnes knowledge, 44 * testimony, witness, from 2wit 45 * Date: before 12th century 46 * 1 : attestation of a fact or event : TESTIMONY 47 * 2 : one that gives evidence; specifically : one who testifies in 48 * a cause or before a judicial tribunal 49 * 3 : one asked to be present at a transaction so as to be able to 50 * testify to its having taken place 51 * 4 : one who has personal knowledge of something 52 * 5 a : something serving as evidence or proof : SIGN 53 * b : public affirmation by word or example of usually 54 * religious faith or conviction <the heroic witness to divine 55 * life -- Pilot> 56 * 6 capitalized : a member of the Jehovah's Witnesses 57 */ 58 59 #include "opt_ddb.h" 60 #include "opt_witness.h" 61 62 #include <sys/param.h> 63 #include <sys/bus.h> 64 #include <sys/kernel.h> 65 #include <sys/ktr.h> 66 #include <sys/lock.h> 67 #include <sys/malloc.h> 68 #include <sys/mutex.h> 69 #include <sys/proc.h> 70 #include <sys/sysctl.h> 71 #include <sys/systm.h> 72 73 #include <ddb/ddb.h> 74 75 /* Define this to check for blessed mutexes */ 76 #undef BLESSING 77 78 #define WITNESS_COUNT 200 79 #define WITNESS_CHILDCOUNT (WITNESS_COUNT * 4) 80 /* 81 * XXX: This is somewhat bogus, as we assume here that at most 1024 threads 82 * will hold LOCK_NCHILDREN * 2 locks. We handle failure ok, and we should 83 * probably be safe for the most part, but it's still a SWAG. 84 */ 85 #define LOCK_CHILDCOUNT (MAXCPU + 1024) * 2 86 87 #define WITNESS_NCHILDREN 6 88 89 struct witness_child_list_entry; 90 91 struct witness { 92 const char *w_name; 93 struct lock_class *w_class; 94 STAILQ_ENTRY(witness) w_list; /* List of all witnesses. */ 95 STAILQ_ENTRY(witness) w_typelist; /* Witnesses of a type. */ 96 struct witness_child_list_entry *w_children; /* Great evilness... */ 97 const char *w_file; 98 int w_line; 99 u_int w_level; 100 u_int w_refcount; 101 u_char w_Giant_squawked:1; 102 u_char w_other_squawked:1; 103 u_char w_same_squawked:1; 104 }; 105 106 struct witness_child_list_entry { 107 struct witness_child_list_entry *wcl_next; 108 struct witness *wcl_children[WITNESS_NCHILDREN]; 109 u_int wcl_count; 110 }; 111 112 STAILQ_HEAD(witness_list, witness); 113 114 #ifdef BLESSING 115 struct witness_blessed { 116 const char *b_lock1; 117 const char *b_lock2; 118 }; 119 #endif 120 121 struct witness_order_list_entry { 122 const char *w_name; 123 struct lock_class *w_class; 124 }; 125 126 static struct witness *enroll(const char *description, 127 struct lock_class *lock_class); 128 static int itismychild(struct witness *parent, struct witness *child); 129 static void removechild(struct witness *parent, struct witness *child); 130 static int isitmychild(struct witness *parent, struct witness *child); 131 static int isitmydescendant(struct witness *parent, struct witness *child); 132 #ifdef BLESSING 133 static int blessed(struct witness *, struct witness *); 134 #endif 135 static void witness_displaydescendants(void(*)(const char *fmt, ...), 136 struct witness *); 137 static void witness_leveldescendents(struct witness *parent, int level); 138 static void witness_levelall(void); 139 static struct witness *witness_get(void); 140 static void witness_free(struct witness *m); 141 static struct witness_child_list_entry *witness_child_get(void); 142 static void witness_child_free(struct witness_child_list_entry *wcl); 143 static struct lock_list_entry *witness_lock_list_get(void); 144 static void witness_lock_list_free(struct lock_list_entry *lle); 145 static struct lock_instance *find_instance(struct lock_list_entry *lock_list, 146 struct lock_object *lock); 147 #if defined(DDB) 148 static void witness_display_list(void(*prnt)(const char *fmt, ...), 149 struct witness_list *list); 150 static void witness_display(void(*)(const char *fmt, ...)); 151 #endif 152 153 MALLOC_DEFINE(M_WITNESS, "witness", "witness structure"); 154 155 static int witness_watch = 1; 156 TUNABLE_INT("debug.witness_watch", &witness_watch); 157 SYSCTL_INT(_debug, OID_AUTO, witness_watch, CTLFLAG_RD, &witness_watch, 0, ""); 158 159 #ifdef DDB 160 /* 161 * When DDB is enabled and witness_ddb is set to 1, it will cause the system to 162 * drop into kdebug() when: 163 * - a lock heirarchy violation occurs 164 * - locks are held when going to sleep. 165 */ 166 #ifdef WITNESS_DDB 167 int witness_ddb = 1; 168 #else 169 int witness_ddb = 0; 170 #endif 171 TUNABLE_INT("debug.witness_ddb", &witness_ddb); 172 SYSCTL_INT(_debug, OID_AUTO, witness_ddb, CTLFLAG_RW, &witness_ddb, 0, ""); 173 174 /* 175 * When DDB is enabled and witness_trace is set to 1, it will cause the system 176 * to print a stack trace: 177 * - a lock heirarchy violation occurs 178 * - locks are held when going to sleep. 179 */ 180 int witness_trace = 1; 181 TUNABLE_INT("debug.witness_trace", &witness_trace); 182 SYSCTL_INT(_debug, OID_AUTO, witness_trace, CTLFLAG_RW, &witness_trace, 0, ""); 183 #endif /* DDB */ 184 185 #ifdef WITNESS_SKIPSPIN 186 int witness_skipspin = 1; 187 #else 188 int witness_skipspin = 0; 189 #endif 190 TUNABLE_INT("debug.witness_skipspin", &witness_skipspin); 191 SYSCTL_INT(_debug, OID_AUTO, witness_skipspin, CTLFLAG_RD, &witness_skipspin, 0, 192 ""); 193 194 static struct mtx w_mtx; 195 static struct witness_list w_free = STAILQ_HEAD_INITIALIZER(w_free); 196 static struct witness_list w_all = STAILQ_HEAD_INITIALIZER(w_all); 197 static struct witness_list w_spin = STAILQ_HEAD_INITIALIZER(w_spin); 198 static struct witness_list w_sleep = STAILQ_HEAD_INITIALIZER(w_sleep); 199 static struct witness_child_list_entry *w_child_free = NULL; 200 static struct lock_list_entry *w_lock_list_free = NULL; 201 static int witness_dead; /* fatal error, probably no memory */ 202 203 static struct witness w_data[WITNESS_COUNT]; 204 static struct witness_child_list_entry w_childdata[WITNESS_CHILDCOUNT]; 205 static struct lock_list_entry w_locklistdata[LOCK_CHILDCOUNT]; 206 207 static struct witness_order_list_entry order_lists[] = { 208 { "Giant", &lock_class_mtx_sleep }, 209 { "proctree", &lock_class_sx }, 210 { "allproc", &lock_class_sx }, 211 { "filedesc structure", &lock_class_mtx_sleep }, 212 { "pipe mutex", &lock_class_mtx_sleep }, 213 { "sigio lock", &lock_class_mtx_sleep }, 214 { "process group", &lock_class_mtx_sleep }, 215 { "process lock", &lock_class_mtx_sleep }, 216 { "session", &lock_class_mtx_sleep }, 217 { "uidinfo hash", &lock_class_mtx_sleep }, 218 { "uidinfo struct", &lock_class_mtx_sleep }, 219 { NULL, NULL }, 220 /* 221 * spin locks 222 */ 223 #ifdef SMP 224 { "ap boot", &lock_class_mtx_spin }, 225 #ifdef __i386__ 226 { "com", &lock_class_mtx_spin }, 227 #endif 228 #endif 229 { "sio", &lock_class_mtx_spin }, 230 #ifdef __i386__ 231 { "cy", &lock_class_mtx_spin }, 232 #endif 233 { "sabtty", &lock_class_mtx_spin }, 234 { "zstty", &lock_class_mtx_spin }, 235 { "ng_node", &lock_class_mtx_spin }, 236 { "ng_worklist", &lock_class_mtx_spin }, 237 { "ithread table lock", &lock_class_mtx_spin }, 238 { "sched lock", &lock_class_mtx_spin }, 239 { "callout", &lock_class_mtx_spin }, 240 /* 241 * leaf locks 242 */ 243 { "allpmaps", &lock_class_mtx_spin }, 244 { "vm page queue free mutex", &lock_class_mtx_spin }, 245 { "icu", &lock_class_mtx_spin }, 246 #ifdef SMP 247 { "smp rendezvous", &lock_class_mtx_spin }, 248 #if defined(__i386__) && defined(APIC_IO) 249 { "tlb", &lock_class_mtx_spin }, 250 #endif 251 #ifdef __sparc64__ 252 { "ipi", &lock_class_mtx_spin }, 253 #endif 254 #endif 255 { "clk", &lock_class_mtx_spin }, 256 { "mutex profiling lock", &lock_class_mtx_spin }, 257 { "kse zombie lock", &lock_class_mtx_spin }, 258 { "ALD Queue", &lock_class_mtx_spin }, 259 #ifdef __ia64__ 260 { "MCA spin lock", &lock_class_mtx_spin }, 261 #endif 262 #ifdef __i386__ 263 { "pcicfg", &lock_class_mtx_spin }, 264 #endif 265 { NULL, NULL }, 266 { NULL, NULL } 267 }; 268 269 #ifdef BLESSING 270 /* 271 * Pairs of locks which have been blessed 272 * Don't complain about order problems with blessed locks 273 */ 274 static struct witness_blessed blessed_list[] = { 275 }; 276 static int blessed_count = 277 sizeof(blessed_list) / sizeof(struct witness_blessed); 278 #endif 279 280 /* 281 * List of all locks in the system. 282 */ 283 TAILQ_HEAD(, lock_object) all_locks = TAILQ_HEAD_INITIALIZER(all_locks); 284 285 static struct mtx all_mtx = { 286 { &lock_class_mtx_sleep, /* mtx_object.lo_class */ 287 "All locks list", /* mtx_object.lo_name */ 288 "All locks list", /* mtx_object.lo_type */ 289 LO_INITIALIZED, /* mtx_object.lo_flags */ 290 { NULL, NULL }, /* mtx_object.lo_list */ 291 NULL }, /* mtx_object.lo_witness */ 292 MTX_UNOWNED, 0, /* mtx_lock, mtx_recurse */ 293 TAILQ_HEAD_INITIALIZER(all_mtx.mtx_blocked), 294 { NULL, NULL } /* mtx_contested */ 295 }; 296 297 /* 298 * This global is set to 0 once it becomes safe to use the witness code. 299 */ 300 static int witness_cold = 1; 301 302 /* 303 * Global variables for book keeping. 304 */ 305 static int lock_cur_cnt; 306 static int lock_max_cnt; 307 308 /* 309 * The WITNESS-enabled diagnostic code. 310 */ 311 static void 312 witness_initialize(void *dummy __unused) 313 { 314 struct lock_object *lock; 315 struct witness_order_list_entry *order; 316 struct witness *w, *w1; 317 int i; 318 319 /* 320 * We have to release Giant before initializing its witness 321 * structure so that WITNESS doesn't get confused. 322 */ 323 mtx_unlock(&Giant); 324 mtx_assert(&Giant, MA_NOTOWNED); 325 326 CTR1(KTR_WITNESS, "%s: initializing witness", __func__); 327 TAILQ_INSERT_HEAD(&all_locks, &all_mtx.mtx_object, lo_list); 328 mtx_init(&w_mtx, "witness lock", NULL, MTX_SPIN | MTX_QUIET | 329 MTX_NOWITNESS); 330 for (i = 0; i < WITNESS_COUNT; i++) 331 witness_free(&w_data[i]); 332 for (i = 0; i < WITNESS_CHILDCOUNT; i++) 333 witness_child_free(&w_childdata[i]); 334 for (i = 0; i < LOCK_CHILDCOUNT; i++) 335 witness_lock_list_free(&w_locklistdata[i]); 336 337 /* First add in all the specified order lists. */ 338 for (order = order_lists; order->w_name != NULL; order++) { 339 w = enroll(order->w_name, order->w_class); 340 if (w == NULL) 341 continue; 342 w->w_file = "order list"; 343 for (order++; order->w_name != NULL; order++) { 344 w1 = enroll(order->w_name, order->w_class); 345 if (w1 == NULL) 346 continue; 347 w1->w_file = "order list"; 348 itismychild(w, w1); 349 w = w1; 350 } 351 } 352 353 /* Iterate through all locks and add them to witness. */ 354 mtx_lock(&all_mtx); 355 TAILQ_FOREACH(lock, &all_locks, lo_list) { 356 if (lock->lo_flags & LO_WITNESS) 357 lock->lo_witness = enroll(lock->lo_type, 358 lock->lo_class); 359 else 360 lock->lo_witness = NULL; 361 } 362 mtx_unlock(&all_mtx); 363 364 /* Mark the witness code as being ready for use. */ 365 atomic_store_rel_int(&witness_cold, 0); 366 367 mtx_lock(&Giant); 368 } 369 SYSINIT(witness_init, SI_SUB_WITNESS, SI_ORDER_FIRST, witness_initialize, NULL) 370 371 void 372 witness_init(struct lock_object *lock) 373 { 374 struct lock_class *class; 375 376 class = lock->lo_class; 377 if (lock->lo_flags & LO_INITIALIZED) 378 panic("%s: lock (%s) %s is already initialized", __func__, 379 class->lc_name, lock->lo_name); 380 if ((lock->lo_flags & LO_RECURSABLE) != 0 && 381 (class->lc_flags & LC_RECURSABLE) == 0) 382 panic("%s: lock (%s) %s can not be recursable", __func__, 383 class->lc_name, lock->lo_name); 384 if ((lock->lo_flags & LO_SLEEPABLE) != 0 && 385 (class->lc_flags & LC_SLEEPABLE) == 0) 386 panic("%s: lock (%s) %s can not be sleepable", __func__, 387 class->lc_name, lock->lo_name); 388 if ((lock->lo_flags & LO_UPGRADABLE) != 0 && 389 (class->lc_flags & LC_UPGRADABLE) == 0) 390 panic("%s: lock (%s) %s can not be upgradable", __func__, 391 class->lc_name, lock->lo_name); 392 393 mtx_lock(&all_mtx); 394 TAILQ_INSERT_TAIL(&all_locks, lock, lo_list); 395 lock->lo_flags |= LO_INITIALIZED; 396 lock_cur_cnt++; 397 if (lock_cur_cnt > lock_max_cnt) 398 lock_max_cnt = lock_cur_cnt; 399 mtx_unlock(&all_mtx); 400 if (!witness_cold && !witness_dead && panicstr == NULL && 401 (lock->lo_flags & LO_WITNESS) != 0) 402 lock->lo_witness = enroll(lock->lo_type, class); 403 else 404 lock->lo_witness = NULL; 405 } 406 407 void 408 witness_destroy(struct lock_object *lock) 409 { 410 struct witness *w; 411 412 if (witness_cold) 413 panic("lock (%s) %s destroyed while witness_cold", 414 lock->lo_class->lc_name, lock->lo_name); 415 if ((lock->lo_flags & LO_INITIALIZED) == 0) 416 panic("%s: lock (%s) %s is not initialized", __func__, 417 lock->lo_class->lc_name, lock->lo_name); 418 419 /* XXX: need to verify that no one holds the lock */ 420 w = lock->lo_witness; 421 if (w != NULL) { 422 mtx_lock_spin(&w_mtx); 423 MPASS(w->w_refcount > 0); 424 w->w_refcount--; 425 mtx_unlock_spin(&w_mtx); 426 } 427 428 mtx_lock(&all_mtx); 429 lock_cur_cnt--; 430 TAILQ_REMOVE(&all_locks, lock, lo_list); 431 lock->lo_flags &= ~LO_INITIALIZED; 432 mtx_unlock(&all_mtx); 433 } 434 435 #if defined(DDB) 436 static void 437 witness_display_list(void(*prnt)(const char *fmt, ...), 438 struct witness_list *list) 439 { 440 struct witness *w, *w1; 441 int found; 442 443 STAILQ_FOREACH(w, list, w_typelist) { 444 if (w->w_file == NULL) 445 continue; 446 found = 0; 447 STAILQ_FOREACH(w1, list, w_typelist) { 448 if (isitmychild(w1, w)) { 449 found++; 450 break; 451 } 452 } 453 if (found) 454 continue; 455 /* 456 * This lock has no anscestors, display its descendants. 457 */ 458 witness_displaydescendants(prnt, w); 459 } 460 } 461 462 static void 463 witness_display(void(*prnt)(const char *fmt, ...)) 464 { 465 struct witness *w; 466 467 KASSERT(!witness_cold, ("%s: witness_cold", __func__)); 468 witness_levelall(); 469 470 /* 471 * First, handle sleep locks which have been acquired at least 472 * once. 473 */ 474 prnt("Sleep locks:\n"); 475 witness_display_list(prnt, &w_sleep); 476 477 /* 478 * Now do spin locks which have been acquired at least once. 479 */ 480 prnt("\nSpin locks:\n"); 481 witness_display_list(prnt, &w_spin); 482 483 /* 484 * Finally, any locks which have not been acquired yet. 485 */ 486 prnt("\nLocks which were never acquired:\n"); 487 STAILQ_FOREACH(w, &w_all, w_list) { 488 if (w->w_file != NULL || w->w_refcount == 0) 489 continue; 490 prnt("%s\n", w->w_name); 491 } 492 } 493 #endif 494 495 void 496 witness_lock(struct lock_object *lock, int flags, const char *file, int line) 497 { 498 struct lock_list_entry **lock_list, *lle; 499 struct lock_instance *lock1, *lock2; 500 struct lock_class *class; 501 struct witness *w, *w1; 502 struct thread *td; 503 int i, j; 504 #ifdef DDB 505 int go_into_ddb = 0; 506 #endif /* DDB */ 507 508 if (witness_cold || witness_dead || lock->lo_witness == NULL || 509 panicstr != NULL) 510 return; 511 w = lock->lo_witness; 512 class = lock->lo_class; 513 td = curthread; 514 515 if (class->lc_flags & LC_SLEEPLOCK) { 516 /* 517 * Since spin locks include a critical section, this check 518 * impliclty enforces a lock order of all sleep locks before 519 * all spin locks. 520 */ 521 if (td->td_critnest != 0 && (flags & LOP_TRYLOCK) == 0) 522 panic("blockable sleep lock (%s) %s @ %s:%d", 523 class->lc_name, lock->lo_name, file, line); 524 lock_list = &td->td_sleeplocks; 525 } else 526 lock_list = PCPU_PTR(spinlocks); 527 528 /* 529 * Try locks do not block if they fail to acquire the lock, thus 530 * there is no danger of deadlocks or of switching while holding a 531 * spin lock if we acquire a lock via a try operation. 532 */ 533 if (flags & LOP_TRYLOCK) 534 goto out; 535 536 /* 537 * Is this the first lock acquired? If so, then no order checking 538 * is needed. 539 */ 540 if (*lock_list == NULL) 541 goto out; 542 543 /* 544 * Check to see if we are recursing on a lock we already own. 545 */ 546 lock1 = find_instance(*lock_list, lock); 547 if (lock1 != NULL) { 548 if ((lock1->li_flags & LI_EXCLUSIVE) != 0 && 549 (flags & LOP_EXCLUSIVE) == 0) { 550 printf("shared lock of (%s) %s @ %s:%d\n", 551 class->lc_name, lock->lo_name, file, line); 552 printf("while exclusively locked from %s:%d\n", 553 lock1->li_file, lock1->li_line); 554 panic("share->excl"); 555 } 556 if ((lock1->li_flags & LI_EXCLUSIVE) == 0 && 557 (flags & LOP_EXCLUSIVE) != 0) { 558 printf("exclusive lock of (%s) %s @ %s:%d\n", 559 class->lc_name, lock->lo_name, file, line); 560 printf("while share locked from %s:%d\n", 561 lock1->li_file, lock1->li_line); 562 panic("excl->share"); 563 } 564 lock1->li_flags++; 565 if ((lock->lo_flags & LO_RECURSABLE) == 0) { 566 printf( 567 "recursed on non-recursive lock (%s) %s @ %s:%d\n", 568 class->lc_name, lock->lo_name, file, line); 569 printf("first acquired @ %s:%d\n", lock1->li_file, 570 lock1->li_line); 571 panic("recurse"); 572 } 573 CTR4(KTR_WITNESS, "%s: pid %d recursed on %s r=%d", __func__, 574 td->td_proc->p_pid, lock->lo_name, 575 lock1->li_flags & LI_RECURSEMASK); 576 lock1->li_file = file; 577 lock1->li_line = line; 578 return; 579 } 580 581 /* 582 * Check for duplicate locks of the same type. Note that we only 583 * have to check for this on the last lock we just acquired. Any 584 * other cases will be caught as lock order violations. 585 */ 586 lock1 = &(*lock_list)->ll_children[(*lock_list)->ll_count - 1]; 587 w1 = lock1->li_lock->lo_witness; 588 if (w1 == w) { 589 if (w->w_same_squawked || (lock->lo_flags & LO_DUPOK)) 590 goto out; 591 w->w_same_squawked = 1; 592 printf("acquiring duplicate lock of same type: \"%s\"\n", 593 lock->lo_type); 594 printf(" 1st %s @ %s:%d\n", lock1->li_lock->lo_name, 595 lock1->li_file, lock1->li_line); 596 printf(" 2nd %s @ %s:%d\n", lock->lo_name, file, line); 597 #ifdef DDB 598 go_into_ddb = 1; 599 #endif /* DDB */ 600 goto out; 601 } 602 MPASS(!mtx_owned(&w_mtx)); 603 mtx_lock_spin(&w_mtx); 604 /* 605 * If we have a known higher number just say ok 606 */ 607 if (witness_watch > 1 && w->w_level > w1->w_level) { 608 mtx_unlock_spin(&w_mtx); 609 goto out; 610 } 611 if (isitmydescendant(w1, w)) { 612 mtx_unlock_spin(&w_mtx); 613 goto out; 614 } 615 for (j = 0, lle = *lock_list; lle != NULL; lle = lle->ll_next) { 616 for (i = lle->ll_count - 1; i >= 0; i--, j++) { 617 618 MPASS(j < WITNESS_COUNT); 619 lock1 = &lle->ll_children[i]; 620 w1 = lock1->li_lock->lo_witness; 621 622 /* 623 * If this lock doesn't undergo witness checking, 624 * then skip it. 625 */ 626 if (w1 == NULL) { 627 KASSERT((lock1->li_lock->lo_flags & LO_WITNESS) == 0, 628 ("lock missing witness structure")); 629 continue; 630 } 631 /* 632 * If we are locking Giant and we slept with this 633 * lock, then skip it. 634 */ 635 if ((lock1->li_flags & LI_SLEPT) != 0 && 636 lock == &Giant.mtx_object) 637 continue; 638 /* 639 * If we are locking a sleepable lock and this lock 640 * isn't sleepable and isn't Giant, we want to treat 641 * it as a lock order violation to enfore a general 642 * lock order of sleepable locks before non-sleepable 643 * locks. Thus, we only bother checking the lock 644 * order hierarchy if we pass the initial test. 645 */ 646 if (!((lock->lo_flags & LO_SLEEPABLE) != 0 && 647 ((lock1->li_lock->lo_flags & LO_SLEEPABLE) == 0 && 648 lock1->li_lock != &Giant.mtx_object)) && 649 !isitmydescendant(w, w1)) 650 continue; 651 /* 652 * We have a lock order violation, check to see if it 653 * is allowed or has already been yelled about. 654 */ 655 mtx_unlock_spin(&w_mtx); 656 #ifdef BLESSING 657 if (blessed(w, w1)) 658 goto out; 659 #endif 660 if (lock1->li_lock == &Giant.mtx_object) { 661 if (w1->w_Giant_squawked) 662 goto out; 663 else 664 w1->w_Giant_squawked = 1; 665 } else { 666 if (w1->w_other_squawked) 667 goto out; 668 else 669 w1->w_other_squawked = 1; 670 } 671 /* 672 * Ok, yell about it. 673 */ 674 printf("lock order reversal\n"); 675 /* 676 * Try to locate an earlier lock with 677 * witness w in our list. 678 */ 679 do { 680 lock2 = &lle->ll_children[i]; 681 MPASS(lock2->li_lock != NULL); 682 if (lock2->li_lock->lo_witness == w) 683 break; 684 i--; 685 if (i == 0 && lle->ll_next != NULL) { 686 lle = lle->ll_next; 687 i = lle->ll_count - 1; 688 MPASS(i >= 0 && i < LOCK_NCHILDREN); 689 } 690 } while (i >= 0); 691 if (i < 0) { 692 printf(" 1st %p %s (%s) @ %s:%d\n", 693 lock1->li_lock, lock1->li_lock->lo_name, 694 lock1->li_lock->lo_type, lock1->li_file, 695 lock1->li_line); 696 printf(" 2nd %p %s (%s) @ %s:%d\n", lock, 697 lock->lo_name, lock->lo_type, file, line); 698 } else { 699 printf(" 1st %p %s (%s) @ %s:%d\n", 700 lock2->li_lock, lock2->li_lock->lo_name, 701 lock2->li_lock->lo_type, lock2->li_file, 702 lock2->li_line); 703 printf(" 2nd %p %s (%s) @ %s:%d\n", 704 lock1->li_lock, lock1->li_lock->lo_name, 705 lock1->li_lock->lo_type, lock1->li_file, 706 lock1->li_line); 707 printf(" 3rd %p %s (%s) @ %s:%d\n", lock, 708 lock->lo_name, lock->lo_type, file, line); 709 } 710 #ifdef DDB 711 go_into_ddb = 1; 712 #endif /* DDB */ 713 goto out; 714 } 715 } 716 lock1 = &(*lock_list)->ll_children[(*lock_list)->ll_count - 1]; 717 /* 718 * Don't build a new relationship if we are locking Giant just 719 * after waking up and the previous lock in the list was acquired 720 * prior to blocking. 721 */ 722 if (lock == &Giant.mtx_object && (lock1->li_flags & LI_SLEPT) != 0) 723 mtx_unlock_spin(&w_mtx); 724 else { 725 CTR3(KTR_WITNESS, "%s: adding %s as a child of %s", __func__, 726 lock->lo_type, lock1->li_lock->lo_type); 727 if (!itismychild(lock1->li_lock->lo_witness, w)) 728 mtx_unlock_spin(&w_mtx); 729 } 730 731 out: 732 #ifdef DDB 733 if (go_into_ddb) { 734 if (witness_trace) 735 backtrace(); 736 if (witness_ddb) 737 Debugger(__func__); 738 } 739 #endif /* DDB */ 740 w->w_file = file; 741 w->w_line = line; 742 743 lle = *lock_list; 744 if (lle == NULL || lle->ll_count == LOCK_NCHILDREN) { 745 lle = witness_lock_list_get(); 746 if (lle == NULL) 747 return; 748 lle->ll_next = *lock_list; 749 CTR3(KTR_WITNESS, "%s: pid %d added lle %p", __func__, 750 td->td_proc->p_pid, lle); 751 *lock_list = lle; 752 } 753 lock1 = &lle->ll_children[lle->ll_count++]; 754 lock1->li_lock = lock; 755 lock1->li_line = line; 756 lock1->li_file = file; 757 if ((flags & LOP_EXCLUSIVE) != 0) 758 lock1->li_flags = LI_EXCLUSIVE; 759 else 760 lock1->li_flags = 0; 761 CTR4(KTR_WITNESS, "%s: pid %d added %s as lle[%d]", __func__, 762 td->td_proc->p_pid, lock->lo_name, lle->ll_count - 1); 763 } 764 765 void 766 witness_upgrade(struct lock_object *lock, int flags, const char *file, int line) 767 { 768 struct lock_instance *instance; 769 struct lock_class *class; 770 771 KASSERT(!witness_cold, ("%s: witness_cold", __func__)); 772 if (lock->lo_witness == NULL || witness_dead || panicstr != NULL) 773 return; 774 class = lock->lo_class; 775 if ((lock->lo_flags & LO_UPGRADABLE) == 0) 776 panic("upgrade of non-upgradable lock (%s) %s @ %s:%d", 777 class->lc_name, lock->lo_name, file, line); 778 if ((flags & LOP_TRYLOCK) == 0) 779 panic("non-try upgrade of lock (%s) %s @ %s:%d", class->lc_name, 780 lock->lo_name, file, line); 781 if ((lock->lo_class->lc_flags & LC_SLEEPLOCK) == 0) 782 panic("upgrade of non-sleep lock (%s) %s @ %s:%d", 783 class->lc_name, lock->lo_name, file, line); 784 instance = find_instance(curthread->td_sleeplocks, lock); 785 if (instance == NULL) 786 panic("upgrade of unlocked lock (%s) %s @ %s:%d", 787 class->lc_name, lock->lo_name, file, line); 788 if ((instance->li_flags & LI_EXCLUSIVE) != 0) 789 panic("upgrade of exclusive lock (%s) %s @ %s:%d", 790 class->lc_name, lock->lo_name, file, line); 791 if ((instance->li_flags & LI_RECURSEMASK) != 0) 792 panic("upgrade of recursed lock (%s) %s r=%d @ %s:%d", 793 class->lc_name, lock->lo_name, 794 instance->li_flags & LI_RECURSEMASK, file, line); 795 instance->li_flags |= LI_EXCLUSIVE; 796 } 797 798 void 799 witness_downgrade(struct lock_object *lock, int flags, const char *file, 800 int line) 801 { 802 struct lock_instance *instance; 803 struct lock_class *class; 804 805 KASSERT(!witness_cold, ("%s: witness_cold", __func__)); 806 if (lock->lo_witness == NULL || witness_dead || panicstr != NULL) 807 return; 808 class = lock->lo_class; 809 if ((lock->lo_flags & LO_UPGRADABLE) == 0) 810 panic("downgrade of non-upgradable lock (%s) %s @ %s:%d", 811 class->lc_name, lock->lo_name, file, line); 812 if ((lock->lo_class->lc_flags & LC_SLEEPLOCK) == 0) 813 panic("downgrade of non-sleep lock (%s) %s @ %s:%d", 814 class->lc_name, lock->lo_name, file, line); 815 instance = find_instance(curthread->td_sleeplocks, lock); 816 if (instance == NULL) 817 panic("downgrade of unlocked lock (%s) %s @ %s:%d", 818 class->lc_name, lock->lo_name, file, line); 819 if ((instance->li_flags & LI_EXCLUSIVE) == 0) 820 panic("downgrade of shared lock (%s) %s @ %s:%d", 821 class->lc_name, lock->lo_name, file, line); 822 if ((instance->li_flags & LI_RECURSEMASK) != 0) 823 panic("downgrade of recursed lock (%s) %s r=%d @ %s:%d", 824 class->lc_name, lock->lo_name, 825 instance->li_flags & LI_RECURSEMASK, file, line); 826 instance->li_flags &= ~LI_EXCLUSIVE; 827 } 828 829 void 830 witness_unlock(struct lock_object *lock, int flags, const char *file, int line) 831 { 832 struct lock_list_entry **lock_list, *lle; 833 struct lock_instance *instance; 834 struct lock_class *class; 835 struct thread *td; 836 register_t s; 837 int i, j; 838 839 if (witness_cold || witness_dead || lock->lo_witness == NULL || 840 panicstr != NULL) 841 return; 842 td = curthread; 843 class = lock->lo_class; 844 if (class->lc_flags & LC_SLEEPLOCK) 845 lock_list = &td->td_sleeplocks; 846 else 847 lock_list = PCPU_PTR(spinlocks); 848 for (; *lock_list != NULL; lock_list = &(*lock_list)->ll_next) 849 for (i = 0; i < (*lock_list)->ll_count; i++) { 850 instance = &(*lock_list)->ll_children[i]; 851 if (instance->li_lock == lock) { 852 if ((instance->li_flags & LI_EXCLUSIVE) != 0 && 853 (flags & LOP_EXCLUSIVE) == 0) { 854 printf( 855 "shared unlock of (%s) %s @ %s:%d\n", 856 class->lc_name, lock->lo_name, 857 file, line); 858 printf( 859 "while exclusively locked from %s:%d\n", 860 instance->li_file, 861 instance->li_line); 862 panic("excl->ushare"); 863 } 864 if ((instance->li_flags & LI_EXCLUSIVE) == 0 && 865 (flags & LOP_EXCLUSIVE) != 0) { 866 printf( 867 "exclusive unlock of (%s) %s @ %s:%d\n", 868 class->lc_name, lock->lo_name, 869 file, line); 870 printf( 871 "while share locked from %s:%d\n", 872 instance->li_file, 873 instance->li_line); 874 panic("share->uexcl"); 875 } 876 /* If we are recursed, unrecurse. */ 877 if ((instance->li_flags & LI_RECURSEMASK) > 0) { 878 CTR4(KTR_WITNESS, 879 "%s: pid %d unrecursed on %s r=%d", __func__, 880 td->td_proc->p_pid, 881 instance->li_lock->lo_name, 882 instance->li_flags); 883 instance->li_flags--; 884 return; 885 } 886 s = intr_disable(); 887 CTR4(KTR_WITNESS, 888 "%s: pid %d removed %s from lle[%d]", __func__, 889 td->td_proc->p_pid, 890 instance->li_lock->lo_name, 891 (*lock_list)->ll_count - 1); 892 for (j = i; j < (*lock_list)->ll_count - 1; j++) 893 (*lock_list)->ll_children[j] = 894 (*lock_list)->ll_children[j + 1]; 895 (*lock_list)->ll_count--; 896 intr_restore(s); 897 if ((*lock_list)->ll_count == 0) { 898 lle = *lock_list; 899 *lock_list = lle->ll_next; 900 CTR3(KTR_WITNESS, 901 "%s: pid %d removed lle %p", __func__, 902 td->td_proc->p_pid, lle); 903 witness_lock_list_free(lle); 904 } 905 return; 906 } 907 } 908 panic("lock (%s) %s not locked @ %s:%d", class->lc_name, lock->lo_name, 909 file, line); 910 } 911 912 /* 913 * Warn if any held locks are not sleepable. Note that Giant and the lock 914 * passed in are both special cases since they are both released during the 915 * sleep process and aren't actually held while the thread is asleep. 916 */ 917 int 918 witness_sleep(int check_only, struct lock_object *lock, const char *file, 919 int line) 920 { 921 struct lock_list_entry **lock_list, *lle; 922 struct lock_instance *lock1; 923 struct thread *td; 924 int i, n; 925 926 if (witness_cold || witness_dead || panicstr != NULL) 927 return (0); 928 n = 0; 929 td = curthread; 930 lock_list = &td->td_sleeplocks; 931 again: 932 for (lle = *lock_list; lle != NULL; lle = lle->ll_next) 933 for (i = lle->ll_count - 1; i >= 0; i--) { 934 lock1 = &lle->ll_children[i]; 935 if (lock1->li_lock == lock || 936 lock1->li_lock == &Giant.mtx_object) 937 continue; 938 if ((lock1->li_lock->lo_flags & LO_SLEEPABLE) != 0) { 939 if (check_only == 0) { 940 CTR3(KTR_WITNESS, 941 "pid %d: sleeping with lock (%s) %s held", 942 td->td_proc->p_pid, 943 lock1->li_lock->lo_class->lc_name, 944 lock1->li_lock->lo_name); 945 lock1->li_flags |= LI_SLEPT; 946 } 947 continue; 948 } 949 n++; 950 printf("%s:%d: %s with \"%s\" locked from %s:%d\n", 951 file, line, check_only ? "could sleep" : "sleeping", 952 lock1->li_lock->lo_name, lock1->li_file, 953 lock1->li_line); 954 } 955 if (lock_list == &td->td_sleeplocks && PCPU_GET(spinlocks) != NULL) { 956 /* 957 * Since we already hold a spinlock preemption is 958 * already blocked. 959 */ 960 lock_list = PCPU_PTR(spinlocks); 961 goto again; 962 } 963 #ifdef DDB 964 if (witness_ddb && n) 965 Debugger(__func__); 966 #endif /* DDB */ 967 return (n); 968 } 969 970 const char * 971 witness_file(struct lock_object *lock) 972 { 973 struct witness *w; 974 975 if (witness_cold || witness_dead || lock->lo_witness == NULL) 976 return ("?"); 977 w = lock->lo_witness; 978 return (w->w_file); 979 } 980 981 int 982 witness_line(struct lock_object *lock) 983 { 984 struct witness *w; 985 986 if (witness_cold || witness_dead || lock->lo_witness == NULL) 987 return (0); 988 w = lock->lo_witness; 989 return (w->w_line); 990 } 991 992 static struct witness * 993 enroll(const char *description, struct lock_class *lock_class) 994 { 995 struct witness *w; 996 997 if (!witness_watch || witness_dead || panicstr != NULL) 998 return (NULL); 999 if ((lock_class->lc_flags & LC_SPINLOCK) && witness_skipspin) 1000 return (NULL); 1001 mtx_lock_spin(&w_mtx); 1002 STAILQ_FOREACH(w, &w_all, w_list) { 1003 if (w->w_name == description || (w->w_refcount > 0 && 1004 strcmp(description, w->w_name) == 0)) { 1005 w->w_refcount++; 1006 mtx_unlock_spin(&w_mtx); 1007 if (lock_class != w->w_class) 1008 panic( 1009 "lock (%s) %s does not match earlier (%s) lock", 1010 description, lock_class->lc_name, 1011 w->w_class->lc_name); 1012 return (w); 1013 } 1014 } 1015 /* 1016 * This isn't quite right, as witness_cold is still 0 while we 1017 * enroll all the locks initialized before witness_initialize(). 1018 */ 1019 if ((lock_class->lc_flags & LC_SPINLOCK) && !witness_cold) { 1020 mtx_unlock_spin(&w_mtx); 1021 panic("spin lock %s not in order list", description); 1022 } 1023 if ((w = witness_get()) == NULL) 1024 return (NULL); 1025 w->w_name = description; 1026 w->w_class = lock_class; 1027 w->w_refcount = 1; 1028 STAILQ_INSERT_HEAD(&w_all, w, w_list); 1029 if (lock_class->lc_flags & LC_SPINLOCK) 1030 STAILQ_INSERT_HEAD(&w_spin, w, w_typelist); 1031 else if (lock_class->lc_flags & LC_SLEEPLOCK) 1032 STAILQ_INSERT_HEAD(&w_sleep, w, w_typelist); 1033 else { 1034 mtx_unlock_spin(&w_mtx); 1035 panic("lock class %s is not sleep or spin", 1036 lock_class->lc_name); 1037 } 1038 mtx_unlock_spin(&w_mtx); 1039 return (w); 1040 } 1041 1042 static int 1043 itismychild(struct witness *parent, struct witness *child) 1044 { 1045 static int recursed; 1046 struct witness_child_list_entry **wcl; 1047 struct witness_list *list; 1048 1049 MPASS(child != NULL && parent != NULL); 1050 if ((parent->w_class->lc_flags & (LC_SLEEPLOCK | LC_SPINLOCK)) != 1051 (child->w_class->lc_flags & (LC_SLEEPLOCK | LC_SPINLOCK))) 1052 panic( 1053 "%s: parent (%s) and child (%s) are not the same lock type", 1054 __func__, parent->w_class->lc_name, 1055 child->w_class->lc_name); 1056 1057 /* 1058 * Insert "child" after "parent" 1059 */ 1060 wcl = &parent->w_children; 1061 while (*wcl != NULL && (*wcl)->wcl_count == WITNESS_NCHILDREN) 1062 wcl = &(*wcl)->wcl_next; 1063 if (*wcl == NULL) { 1064 *wcl = witness_child_get(); 1065 if (*wcl == NULL) 1066 return (1); 1067 } 1068 (*wcl)->wcl_children[(*wcl)->wcl_count++] = child; 1069 1070 /* 1071 * Now prune whole tree. We look for cases where a lock is now 1072 * both a descendant and a direct child of a given lock. In that 1073 * case, we want to remove the direct child link from the tree. 1074 */ 1075 if (recursed) 1076 return (0); 1077 recursed = 1; 1078 if (parent->w_class->lc_flags & LC_SLEEPLOCK) 1079 list = &w_sleep; 1080 else 1081 list = &w_spin; 1082 STAILQ_FOREACH(child, list, w_typelist) { 1083 STAILQ_FOREACH(parent, list, w_typelist) { 1084 if (!isitmychild(parent, child)) 1085 continue; 1086 removechild(parent, child); 1087 if (isitmydescendant(parent, child)) 1088 continue; 1089 itismychild(parent, child); 1090 } 1091 } 1092 recursed = 0; 1093 witness_levelall(); 1094 return (0); 1095 } 1096 1097 static void 1098 removechild(struct witness *parent, struct witness *child) 1099 { 1100 struct witness_child_list_entry **wcl, *wcl1; 1101 int i; 1102 1103 for (wcl = &parent->w_children; *wcl != NULL; wcl = &(*wcl)->wcl_next) 1104 for (i = 0; i < (*wcl)->wcl_count; i++) 1105 if ((*wcl)->wcl_children[i] == child) 1106 goto found; 1107 return; 1108 found: 1109 (*wcl)->wcl_count--; 1110 if ((*wcl)->wcl_count > i) 1111 (*wcl)->wcl_children[i] = 1112 (*wcl)->wcl_children[(*wcl)->wcl_count]; 1113 MPASS((*wcl)->wcl_children[i] != NULL); 1114 if ((*wcl)->wcl_count != 0) 1115 return; 1116 wcl1 = *wcl; 1117 *wcl = wcl1->wcl_next; 1118 witness_child_free(wcl1); 1119 } 1120 1121 static int 1122 isitmychild(struct witness *parent, struct witness *child) 1123 { 1124 struct witness_child_list_entry *wcl; 1125 int i; 1126 1127 for (wcl = parent->w_children; wcl != NULL; wcl = wcl->wcl_next) { 1128 for (i = 0; i < wcl->wcl_count; i++) { 1129 if (wcl->wcl_children[i] == child) 1130 return (1); 1131 } 1132 } 1133 return (0); 1134 } 1135 1136 static int 1137 isitmydescendant(struct witness *parent, struct witness *child) 1138 { 1139 struct witness_child_list_entry *wcl; 1140 int i, j; 1141 1142 if (isitmychild(parent, child)) 1143 return (1); 1144 j = 0; 1145 for (wcl = parent->w_children; wcl != NULL; wcl = wcl->wcl_next) { 1146 MPASS(j < 1000); 1147 for (i = 0; i < wcl->wcl_count; i++) { 1148 if (isitmydescendant(wcl->wcl_children[i], child)) 1149 return (1); 1150 } 1151 j++; 1152 } 1153 return (0); 1154 } 1155 1156 static void 1157 witness_levelall (void) 1158 { 1159 struct witness_list *list; 1160 struct witness *w, *w1; 1161 1162 /* 1163 * First clear all levels. 1164 */ 1165 STAILQ_FOREACH(w, &w_all, w_list) { 1166 w->w_level = 0; 1167 } 1168 1169 /* 1170 * Look for locks with no parent and level all their descendants. 1171 */ 1172 STAILQ_FOREACH(w, &w_all, w_list) { 1173 /* 1174 * This is just an optimization, technically we could get 1175 * away just walking the all list each time. 1176 */ 1177 if (w->w_class->lc_flags & LC_SLEEPLOCK) 1178 list = &w_sleep; 1179 else 1180 list = &w_spin; 1181 STAILQ_FOREACH(w1, list, w_typelist) { 1182 if (isitmychild(w1, w)) 1183 goto skip; 1184 } 1185 witness_leveldescendents(w, 0); 1186 skip: 1187 ; /* silence GCC 3.x */ 1188 } 1189 } 1190 1191 static void 1192 witness_leveldescendents(struct witness *parent, int level) 1193 { 1194 struct witness_child_list_entry *wcl; 1195 int i; 1196 1197 if (parent->w_level < level) 1198 parent->w_level = level; 1199 level++; 1200 for (wcl = parent->w_children; wcl != NULL; wcl = wcl->wcl_next) 1201 for (i = 0; i < wcl->wcl_count; i++) 1202 witness_leveldescendents(wcl->wcl_children[i], level); 1203 } 1204 1205 static void 1206 witness_displaydescendants(void(*prnt)(const char *fmt, ...), 1207 struct witness *parent) 1208 { 1209 struct witness_child_list_entry *wcl; 1210 int i, level; 1211 1212 level = parent->w_level; 1213 prnt("%-2d", level); 1214 for (i = 0; i < level; i++) 1215 prnt(" "); 1216 if (parent->w_refcount > 0) { 1217 prnt("%s", parent->w_name); 1218 if (parent->w_file != NULL) 1219 prnt(" -- last acquired @ %s:%d\n", parent->w_file, 1220 parent->w_line); 1221 } else 1222 prnt("(dead)\n"); 1223 for (wcl = parent->w_children; wcl != NULL; wcl = wcl->wcl_next) 1224 for (i = 0; i < wcl->wcl_count; i++) 1225 witness_displaydescendants(prnt, 1226 wcl->wcl_children[i]); 1227 } 1228 1229 #ifdef BLESSING 1230 static int 1231 blessed(struct witness *w1, struct witness *w2) 1232 { 1233 int i; 1234 struct witness_blessed *b; 1235 1236 for (i = 0; i < blessed_count; i++) { 1237 b = &blessed_list[i]; 1238 if (strcmp(w1->w_name, b->b_lock1) == 0) { 1239 if (strcmp(w2->w_name, b->b_lock2) == 0) 1240 return (1); 1241 continue; 1242 } 1243 if (strcmp(w1->w_name, b->b_lock2) == 0) 1244 if (strcmp(w2->w_name, b->b_lock1) == 0) 1245 return (1); 1246 } 1247 return (0); 1248 } 1249 #endif 1250 1251 static struct witness * 1252 witness_get(void) 1253 { 1254 struct witness *w; 1255 1256 if (witness_dead) { 1257 mtx_unlock_spin(&w_mtx); 1258 return (NULL); 1259 } 1260 if (STAILQ_EMPTY(&w_free)) { 1261 witness_dead = 1; 1262 mtx_unlock_spin(&w_mtx); 1263 printf("%s: witness exhausted\n", __func__); 1264 return (NULL); 1265 } 1266 w = STAILQ_FIRST(&w_free); 1267 STAILQ_REMOVE_HEAD(&w_free, w_list); 1268 bzero(w, sizeof(*w)); 1269 return (w); 1270 } 1271 1272 static void 1273 witness_free(struct witness *w) 1274 { 1275 1276 STAILQ_INSERT_HEAD(&w_free, w, w_list); 1277 } 1278 1279 static struct witness_child_list_entry * 1280 witness_child_get(void) 1281 { 1282 struct witness_child_list_entry *wcl; 1283 1284 if (witness_dead) { 1285 mtx_unlock_spin(&w_mtx); 1286 return (NULL); 1287 } 1288 wcl = w_child_free; 1289 if (wcl == NULL) { 1290 witness_dead = 1; 1291 mtx_unlock_spin(&w_mtx); 1292 printf("%s: witness exhausted\n", __func__); 1293 return (NULL); 1294 } 1295 w_child_free = wcl->wcl_next; 1296 bzero(wcl, sizeof(*wcl)); 1297 return (wcl); 1298 } 1299 1300 static void 1301 witness_child_free(struct witness_child_list_entry *wcl) 1302 { 1303 1304 wcl->wcl_next = w_child_free; 1305 w_child_free = wcl; 1306 } 1307 1308 static struct lock_list_entry * 1309 witness_lock_list_get(void) 1310 { 1311 struct lock_list_entry *lle; 1312 1313 if (witness_dead) 1314 return (NULL); 1315 mtx_lock_spin(&w_mtx); 1316 lle = w_lock_list_free; 1317 if (lle == NULL) { 1318 witness_dead = 1; 1319 mtx_unlock_spin(&w_mtx); 1320 printf("%s: witness exhausted\n", __func__); 1321 return (NULL); 1322 } 1323 w_lock_list_free = lle->ll_next; 1324 mtx_unlock_spin(&w_mtx); 1325 bzero(lle, sizeof(*lle)); 1326 return (lle); 1327 } 1328 1329 static void 1330 witness_lock_list_free(struct lock_list_entry *lle) 1331 { 1332 1333 mtx_lock_spin(&w_mtx); 1334 lle->ll_next = w_lock_list_free; 1335 w_lock_list_free = lle; 1336 mtx_unlock_spin(&w_mtx); 1337 } 1338 1339 static struct lock_instance * 1340 find_instance(struct lock_list_entry *lock_list, struct lock_object *lock) 1341 { 1342 struct lock_list_entry *lle; 1343 struct lock_instance *instance; 1344 int i; 1345 1346 for (lle = lock_list; lle != NULL; lle = lle->ll_next) 1347 for (i = lle->ll_count - 1; i >= 0; i--) { 1348 instance = &lle->ll_children[i]; 1349 if (instance->li_lock == lock) 1350 return (instance); 1351 } 1352 return (NULL); 1353 } 1354 1355 int 1356 witness_list_locks(struct lock_list_entry **lock_list) 1357 { 1358 struct lock_list_entry *lle; 1359 struct lock_instance *instance; 1360 struct lock_object *lock; 1361 int i, nheld; 1362 1363 nheld = 0; 1364 for (lle = *lock_list; lle != NULL; lle = lle->ll_next) 1365 for (i = lle->ll_count - 1; i >= 0; i--) { 1366 instance = &lle->ll_children[i]; 1367 lock = instance->li_lock; 1368 printf("%s %s %s", 1369 (instance->li_flags & LI_EXCLUSIVE) != 0 ? 1370 "exclusive" : "shared", 1371 lock->lo_class->lc_name, lock->lo_name); 1372 if (lock->lo_type != lock->lo_name) 1373 printf(" (%s)", lock->lo_type); 1374 printf(" r = %d (%p) locked @ %s:%d\n", 1375 instance->li_flags & LI_RECURSEMASK, lock, 1376 instance->li_file, instance->li_line); 1377 nheld++; 1378 } 1379 return (nheld); 1380 } 1381 1382 /* 1383 * Calling this on td != curthread is bad unless we are in ddb. 1384 */ 1385 int 1386 witness_list(struct thread *td) 1387 { 1388 int nheld; 1389 1390 KASSERT(!witness_cold, ("%s: witness_cold", __func__)); 1391 #ifdef DDB 1392 KASSERT(td == curthread || db_active, 1393 ("%s: td != curthread and we aren't in the debugger", __func__)); 1394 if (!db_active && witness_dead) 1395 return (0); 1396 #else 1397 KASSERT(td == curthread, ("%s: p != curthread", __func__)); 1398 if (witness_dead) 1399 return (0); 1400 #endif 1401 nheld = witness_list_locks(&td->td_sleeplocks); 1402 1403 /* 1404 * We only handle spinlocks if td == curthread. This is somewhat broken 1405 * if td is currently executing on some other CPU and holds spin locks 1406 * as we won't display those locks. If we had a MI way of getting 1407 * the per-cpu data for a given cpu then we could use 1408 * td->td_kse->ke_oncpu to get the list of spinlocks for this thread 1409 * and "fix" this. 1410 * 1411 * That still wouldn't really fix this unless we locked sched_lock 1412 * or stopped the other CPU to make sure it wasn't changing the list 1413 * out from under us. It is probably best to just not try to handle 1414 * threads on other CPU's for now. 1415 */ 1416 if (td == curthread && PCPU_GET(spinlocks) != NULL) 1417 nheld += witness_list_locks(PCPU_PTR(spinlocks)); 1418 1419 return (nheld); 1420 } 1421 1422 void 1423 witness_save(struct lock_object *lock, const char **filep, int *linep) 1424 { 1425 struct lock_instance *instance; 1426 1427 KASSERT(!witness_cold, ("%s: witness_cold", __func__)); 1428 if (lock->lo_witness == NULL || witness_dead || panicstr != NULL) 1429 return; 1430 if ((lock->lo_class->lc_flags & LC_SLEEPLOCK) == 0) 1431 panic("%s: lock (%s) %s is not a sleep lock", __func__, 1432 lock->lo_class->lc_name, lock->lo_name); 1433 instance = find_instance(curthread->td_sleeplocks, lock); 1434 if (instance == NULL) 1435 panic("%s: lock (%s) %s not locked", __func__, 1436 lock->lo_class->lc_name, lock->lo_name); 1437 *filep = instance->li_file; 1438 *linep = instance->li_line; 1439 } 1440 1441 void 1442 witness_restore(struct lock_object *lock, const char *file, int line) 1443 { 1444 struct lock_instance *instance; 1445 1446 KASSERT(!witness_cold, ("%s: witness_cold", __func__)); 1447 if (lock->lo_witness == NULL || witness_dead || panicstr != NULL) 1448 return; 1449 if ((lock->lo_class->lc_flags & LC_SLEEPLOCK) == 0) 1450 panic("%s: lock (%s) %s is not a sleep lock", __func__, 1451 lock->lo_class->lc_name, lock->lo_name); 1452 instance = find_instance(curthread->td_sleeplocks, lock); 1453 if (instance == NULL) 1454 panic("%s: lock (%s) %s not locked", __func__, 1455 lock->lo_class->lc_name, lock->lo_name); 1456 lock->lo_witness->w_file = file; 1457 lock->lo_witness->w_line = line; 1458 instance->li_file = file; 1459 instance->li_line = line; 1460 } 1461 1462 void 1463 witness_assert(struct lock_object *lock, int flags, const char *file, int line) 1464 { 1465 #ifdef INVARIANT_SUPPORT 1466 struct lock_instance *instance; 1467 1468 if (lock->lo_witness == NULL || witness_dead || panicstr != NULL) 1469 return; 1470 if ((lock->lo_class->lc_flags & LC_SLEEPLOCK) != 0) 1471 instance = find_instance(curthread->td_sleeplocks, lock); 1472 else if ((lock->lo_class->lc_flags & LC_SPINLOCK) != 0) 1473 instance = find_instance(PCPU_GET(spinlocks), lock); 1474 else { 1475 panic("Lock (%s) %s is not sleep or spin!", 1476 lock->lo_class->lc_name, lock->lo_name); 1477 return; 1478 } 1479 switch (flags) { 1480 case LA_UNLOCKED: 1481 if (instance != NULL) 1482 panic("Lock (%s) %s locked @ %s:%d.", 1483 lock->lo_class->lc_name, lock->lo_name, file, line); 1484 break; 1485 case LA_LOCKED: 1486 case LA_LOCKED | LA_RECURSED: 1487 case LA_LOCKED | LA_NOTRECURSED: 1488 case LA_SLOCKED: 1489 case LA_SLOCKED | LA_RECURSED: 1490 case LA_SLOCKED | LA_NOTRECURSED: 1491 case LA_XLOCKED: 1492 case LA_XLOCKED | LA_RECURSED: 1493 case LA_XLOCKED | LA_NOTRECURSED: 1494 if (instance == NULL) { 1495 panic("Lock (%s) %s not locked @ %s:%d.", 1496 lock->lo_class->lc_name, lock->lo_name, file, line); 1497 break; 1498 } 1499 if ((flags & LA_XLOCKED) != 0 && 1500 (instance->li_flags & LI_EXCLUSIVE) == 0) 1501 panic("Lock (%s) %s not exclusively locked @ %s:%d.", 1502 lock->lo_class->lc_name, lock->lo_name, file, line); 1503 if ((flags & LA_SLOCKED) != 0 && 1504 (instance->li_flags & LI_EXCLUSIVE) != 0) 1505 panic("Lock (%s) %s exclusively locked @ %s:%d.", 1506 lock->lo_class->lc_name, lock->lo_name, file, line); 1507 if ((flags & LA_RECURSED) != 0 && 1508 (instance->li_flags & LI_RECURSEMASK) == 0) 1509 panic("Lock (%s) %s not recursed @ %s:%d.", 1510 lock->lo_class->lc_name, lock->lo_name, file, line); 1511 if ((flags & LA_NOTRECURSED) != 0 && 1512 (instance->li_flags & LI_RECURSEMASK) != 0) 1513 panic("Lock (%s) %s recursed @ %s:%d.", 1514 lock->lo_class->lc_name, lock->lo_name, file, line); 1515 break; 1516 default: 1517 panic("Invalid lock assertion at %s:%d.", file, line); 1518 1519 } 1520 #endif /* INVARIANT_SUPPORT */ 1521 } 1522 1523 #ifdef DDB 1524 1525 DB_SHOW_COMMAND(locks, db_witness_list) 1526 { 1527 struct thread *td; 1528 pid_t pid; 1529 struct proc *p; 1530 1531 if (have_addr) { 1532 pid = (addr % 16) + ((addr >> 4) % 16) * 10 + 1533 ((addr >> 8) % 16) * 100 + ((addr >> 12) % 16) * 1000 + 1534 ((addr >> 16) % 16) * 10000; 1535 /* sx_slock(&allproc_lock); */ 1536 FOREACH_PROC_IN_SYSTEM(p) { 1537 if (p->p_pid == pid) 1538 break; 1539 } 1540 /* sx_sunlock(&allproc_lock); */ 1541 if (p == NULL) { 1542 db_printf("pid %d not found\n", pid); 1543 return; 1544 } 1545 FOREACH_THREAD_IN_PROC(p, td) { 1546 witness_list(td); 1547 } 1548 } else { 1549 td = curthread; 1550 witness_list(td); 1551 } 1552 } 1553 1554 DB_SHOW_COMMAND(witness, db_witness_display) 1555 { 1556 1557 witness_display(db_printf); 1558 } 1559 #endif 1560