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FreeBSD/Linux Kernel Cross Reference
sys/kern/subr_witness.c
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1 /*- 2 * Copyright (c) 1998 Berkeley Software Design, Inc. All rights reserved. 3 * 4 * Redistribution and use in source and binary forms, with or without 5 * modification, are permitted provided that the following conditions 6 * are met: 7 * 1. Redistributions of source code must retain the above copyright 8 * notice, this list of conditions and the following disclaimer. 9 * 2. Redistributions in binary form must reproduce the above copyright 10 * notice, this list of conditions and the following disclaimer in the 11 * documentation and/or other materials provided with the distribution. 12 * 3. Berkeley Software Design Inc's name may not be used to endorse or 13 * promote products derived from this software without specific prior 14 * written permission. 15 * 16 * THIS SOFTWARE IS PROVIDED BY BERKELEY SOFTWARE DESIGN INC ``AS IS'' AND 17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 19 * ARE DISCLAIMED. IN NO EVENT SHALL BERKELEY SOFTWARE DESIGN INC BE LIABLE 20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26 * SUCH DAMAGE. 27 * 28 * from BSDI $Id: mutex_witness.c,v 1.1.2.20 2000/04/27 03:10:27 cp Exp $ 29 * and BSDI $Id: synch_machdep.c,v 2.3.2.39 2000/04/27 03:10:25 cp Exp $ 30 * $FreeBSD: releng/5.0/sys/kern/subr_witness.c 108185 2002-12-22 16:33:39Z kris $ 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 #endif /* DDB */ 174 175 #ifdef WITNESS_SKIPSPIN 176 int witness_skipspin = 1; 177 #else 178 int witness_skipspin = 0; 179 #endif 180 TUNABLE_INT("debug.witness_skipspin", &witness_skipspin); 181 SYSCTL_INT(_debug, OID_AUTO, witness_skipspin, CTLFLAG_RD, &witness_skipspin, 0, 182 ""); 183 184 static struct mtx w_mtx; 185 static struct witness_list w_free = STAILQ_HEAD_INITIALIZER(w_free); 186 static struct witness_list w_all = STAILQ_HEAD_INITIALIZER(w_all); 187 static struct witness_list w_spin = STAILQ_HEAD_INITIALIZER(w_spin); 188 static struct witness_list w_sleep = STAILQ_HEAD_INITIALIZER(w_sleep); 189 static struct witness_child_list_entry *w_child_free = NULL; 190 static struct lock_list_entry *w_lock_list_free = NULL; 191 static int witness_dead; /* fatal error, probably no memory */ 192 193 static struct witness w_data[WITNESS_COUNT]; 194 static struct witness_child_list_entry w_childdata[WITNESS_CHILDCOUNT]; 195 static struct lock_list_entry w_locklistdata[LOCK_CHILDCOUNT]; 196 197 static struct witness_order_list_entry order_lists[] = { 198 { "Giant", &lock_class_mtx_sleep }, 199 { "proctree", &lock_class_sx }, 200 { "allproc", &lock_class_sx }, 201 { "filedesc structure", &lock_class_mtx_sleep }, 202 { "pipe mutex", &lock_class_mtx_sleep }, 203 { "sigio lock", &lock_class_mtx_sleep }, 204 { "process group", &lock_class_mtx_sleep }, 205 { "process lock", &lock_class_mtx_sleep }, 206 { "session", &lock_class_mtx_sleep }, 207 { "uidinfo hash", &lock_class_mtx_sleep }, 208 { "uidinfo struct", &lock_class_mtx_sleep }, 209 { NULL, NULL }, 210 /* 211 * spin locks 212 */ 213 #ifdef SMP 214 { "ap boot", &lock_class_mtx_spin }, 215 #ifdef __i386__ 216 { "com", &lock_class_mtx_spin }, 217 #endif 218 #endif 219 { "sio", &lock_class_mtx_spin }, 220 #ifdef __i386__ 221 { "cy", &lock_class_mtx_spin }, 222 #endif 223 { "sabtty", &lock_class_mtx_spin }, 224 { "ng_node", &lock_class_mtx_spin }, 225 { "ng_worklist", &lock_class_mtx_spin }, 226 { "ithread table lock", &lock_class_mtx_spin }, 227 { "sched lock", &lock_class_mtx_spin }, 228 { "callout", &lock_class_mtx_spin }, 229 /* 230 * leaf locks 231 */ 232 { "allpmaps", &lock_class_mtx_spin }, 233 { "vm page queue free mutex", &lock_class_mtx_spin }, 234 { "icu", &lock_class_mtx_spin }, 235 #ifdef SMP 236 { "smp rendezvous", &lock_class_mtx_spin }, 237 #if defined(__i386__) && defined(APIC_IO) 238 { "tlb", &lock_class_mtx_spin }, 239 #endif 240 #endif 241 { "clk", &lock_class_mtx_spin }, 242 { "mutex profiling lock", &lock_class_mtx_spin }, 243 { "zombie_thread_lock", &lock_class_mtx_spin }, 244 { "ALD Queue", &lock_class_mtx_spin }, 245 #ifdef __ia64__ 246 { "MCA spin lock", &lock_class_mtx_spin }, 247 #endif 248 { NULL, NULL }, 249 { NULL, NULL } 250 }; 251 252 #ifdef BLESSING 253 /* 254 * Pairs of locks which have been blessed 255 * Don't complain about order problems with blessed locks 256 */ 257 static struct witness_blessed blessed_list[] = { 258 }; 259 static int blessed_count = 260 sizeof(blessed_list) / sizeof(struct witness_blessed); 261 #endif 262 263 /* 264 * List of all locks in the system. 265 */ 266 TAILQ_HEAD(, lock_object) all_locks = TAILQ_HEAD_INITIALIZER(all_locks); 267 268 static struct mtx all_mtx = { 269 { &lock_class_mtx_sleep, /* mtx_object.lo_class */ 270 "All locks list", /* mtx_object.lo_name */ 271 "All locks list", /* mtx_object.lo_type */ 272 LO_INITIALIZED, /* mtx_object.lo_flags */ 273 { NULL, NULL }, /* mtx_object.lo_list */ 274 NULL }, /* mtx_object.lo_witness */ 275 MTX_UNOWNED, 0, /* mtx_lock, mtx_recurse */ 276 TAILQ_HEAD_INITIALIZER(all_mtx.mtx_blocked), 277 { NULL, NULL } /* mtx_contested */ 278 }; 279 280 /* 281 * This global is set to 0 once it becomes safe to use the witness code. 282 */ 283 static int witness_cold = 1; 284 285 /* 286 * Global variables for book keeping. 287 */ 288 static int lock_cur_cnt; 289 static int lock_max_cnt; 290 291 /* 292 * The WITNESS-enabled diagnostic code. 293 */ 294 static void 295 witness_initialize(void *dummy __unused) 296 { 297 struct lock_object *lock; 298 struct witness_order_list_entry *order; 299 struct witness *w, *w1; 300 int i; 301 302 /* 303 * We have to release Giant before initializing its witness 304 * structure so that WITNESS doesn't get confused. 305 */ 306 mtx_unlock(&Giant); 307 mtx_assert(&Giant, MA_NOTOWNED); 308 309 CTR1(KTR_WITNESS, "%s: initializing witness", __func__); 310 TAILQ_INSERT_HEAD(&all_locks, &all_mtx.mtx_object, lo_list); 311 mtx_init(&w_mtx, "witness lock", NULL, MTX_SPIN | MTX_QUIET | 312 MTX_NOWITNESS); 313 for (i = 0; i < WITNESS_COUNT; i++) 314 witness_free(&w_data[i]); 315 for (i = 0; i < WITNESS_CHILDCOUNT; i++) 316 witness_child_free(&w_childdata[i]); 317 for (i = 0; i < LOCK_CHILDCOUNT; i++) 318 witness_lock_list_free(&w_locklistdata[i]); 319 320 /* First add in all the specified order lists. */ 321 for (order = order_lists; order->w_name != NULL; order++) { 322 w = enroll(order->w_name, order->w_class); 323 if (w == NULL) 324 continue; 325 w->w_file = "order list"; 326 for (order++; order->w_name != NULL; order++) { 327 w1 = enroll(order->w_name, order->w_class); 328 if (w1 == NULL) 329 continue; 330 w1->w_file = "order list"; 331 itismychild(w, w1); 332 w = w1; 333 } 334 } 335 336 /* Iterate through all locks and add them to witness. */ 337 mtx_lock(&all_mtx); 338 TAILQ_FOREACH(lock, &all_locks, lo_list) { 339 if (lock->lo_flags & LO_WITNESS) 340 lock->lo_witness = enroll(lock->lo_type, 341 lock->lo_class); 342 else 343 lock->lo_witness = NULL; 344 } 345 mtx_unlock(&all_mtx); 346 347 /* Mark the witness code as being ready for use. */ 348 atomic_store_rel_int(&witness_cold, 0); 349 350 mtx_lock(&Giant); 351 } 352 SYSINIT(witness_init, SI_SUB_WITNESS, SI_ORDER_FIRST, witness_initialize, NULL) 353 354 void 355 witness_init(struct lock_object *lock) 356 { 357 struct lock_class *class; 358 359 class = lock->lo_class; 360 if (lock->lo_flags & LO_INITIALIZED) 361 panic("%s: lock (%s) %s is already initialized", __func__, 362 class->lc_name, lock->lo_name); 363 if ((lock->lo_flags & LO_RECURSABLE) != 0 && 364 (class->lc_flags & LC_RECURSABLE) == 0) 365 panic("%s: lock (%s) %s can not be recursable", __func__, 366 class->lc_name, lock->lo_name); 367 if ((lock->lo_flags & LO_SLEEPABLE) != 0 && 368 (class->lc_flags & LC_SLEEPABLE) == 0) 369 panic("%s: lock (%s) %s can not be sleepable", __func__, 370 class->lc_name, lock->lo_name); 371 if ((lock->lo_flags & LO_UPGRADABLE) != 0 && 372 (class->lc_flags & LC_UPGRADABLE) == 0) 373 panic("%s: lock (%s) %s can not be upgradable", __func__, 374 class->lc_name, lock->lo_name); 375 376 mtx_lock(&all_mtx); 377 TAILQ_INSERT_TAIL(&all_locks, lock, lo_list); 378 lock->lo_flags |= LO_INITIALIZED; 379 lock_cur_cnt++; 380 if (lock_cur_cnt > lock_max_cnt) 381 lock_max_cnt = lock_cur_cnt; 382 mtx_unlock(&all_mtx); 383 if (!witness_cold && !witness_dead && panicstr == NULL && 384 (lock->lo_flags & LO_WITNESS) != 0) 385 lock->lo_witness = enroll(lock->lo_type, class); 386 else 387 lock->lo_witness = NULL; 388 } 389 390 void 391 witness_destroy(struct lock_object *lock) 392 { 393 struct witness *w; 394 395 if (witness_cold) 396 panic("lock (%s) %s destroyed while witness_cold", 397 lock->lo_class->lc_name, lock->lo_name); 398 if ((lock->lo_flags & LO_INITIALIZED) == 0) 399 panic("%s: lock (%s) %s is not initialized", __func__, 400 lock->lo_class->lc_name, lock->lo_name); 401 402 /* XXX: need to verify that no one holds the lock */ 403 w = lock->lo_witness; 404 if (w != NULL) { 405 mtx_lock_spin(&w_mtx); 406 MPASS(w->w_refcount > 0); 407 w->w_refcount--; 408 mtx_unlock_spin(&w_mtx); 409 } 410 411 mtx_lock(&all_mtx); 412 lock_cur_cnt--; 413 TAILQ_REMOVE(&all_locks, lock, lo_list); 414 lock->lo_flags &= ~LO_INITIALIZED; 415 mtx_unlock(&all_mtx); 416 } 417 418 #if defined(DDB) 419 static void 420 witness_display_list(void(*prnt)(const char *fmt, ...), 421 struct witness_list *list) 422 { 423 struct witness *w, *w1; 424 int found; 425 426 STAILQ_FOREACH(w, list, w_typelist) { 427 if (w->w_file == NULL) 428 continue; 429 found = 0; 430 STAILQ_FOREACH(w1, list, w_typelist) { 431 if (isitmychild(w1, w)) { 432 found++; 433 break; 434 } 435 } 436 if (found) 437 continue; 438 /* 439 * This lock has no anscestors, display its descendants. 440 */ 441 witness_displaydescendants(prnt, w); 442 } 443 } 444 445 static void 446 witness_display(void(*prnt)(const char *fmt, ...)) 447 { 448 struct witness *w; 449 450 KASSERT(!witness_cold, ("%s: witness_cold", __func__)); 451 witness_levelall(); 452 453 /* 454 * First, handle sleep locks which have been acquired at least 455 * once. 456 */ 457 prnt("Sleep locks:\n"); 458 witness_display_list(prnt, &w_sleep); 459 460 /* 461 * Now do spin locks which have been acquired at least once. 462 */ 463 prnt("\nSpin locks:\n"); 464 witness_display_list(prnt, &w_spin); 465 466 /* 467 * Finally, any locks which have not been acquired yet. 468 */ 469 prnt("\nLocks which were never acquired:\n"); 470 STAILQ_FOREACH(w, &w_all, w_list) { 471 if (w->w_file != NULL || w->w_refcount == 0) 472 continue; 473 prnt("%s\n", w->w_name); 474 } 475 } 476 #endif 477 478 void 479 witness_lock(struct lock_object *lock, int flags, const char *file, int line) 480 { 481 struct lock_list_entry **lock_list, *lle; 482 struct lock_instance *lock1, *lock2; 483 struct lock_class *class; 484 struct witness *w, *w1; 485 struct thread *td; 486 int i, j; 487 #ifdef DDB 488 int go_into_ddb = 0; 489 #endif /* DDB */ 490 491 if (witness_cold || witness_dead || lock->lo_witness == NULL || 492 panicstr != NULL) 493 return; 494 w = lock->lo_witness; 495 class = lock->lo_class; 496 td = curthread; 497 498 if (class->lc_flags & LC_SLEEPLOCK) { 499 /* 500 * Since spin locks include a critical section, this check 501 * impliclty enforces a lock order of all sleep locks before 502 * all spin locks. 503 */ 504 if (td->td_critnest != 0 && (flags & LOP_TRYLOCK) == 0) 505 panic("blockable sleep lock (%s) %s @ %s:%d", 506 class->lc_name, lock->lo_name, file, line); 507 lock_list = &td->td_sleeplocks; 508 } else 509 lock_list = PCPU_PTR(spinlocks); 510 511 /* 512 * Try locks do not block if they fail to acquire the lock, thus 513 * there is no danger of deadlocks or of switching while holding a 514 * spin lock if we acquire a lock via a try operation. 515 */ 516 if (flags & LOP_TRYLOCK) 517 goto out; 518 519 /* 520 * Is this the first lock acquired? If so, then no order checking 521 * is needed. 522 */ 523 if (*lock_list == NULL) 524 goto out; 525 526 /* 527 * Check to see if we are recursing on a lock we already own. 528 */ 529 lock1 = find_instance(*lock_list, lock); 530 if (lock1 != NULL) { 531 if ((lock1->li_flags & LI_EXCLUSIVE) != 0 && 532 (flags & LOP_EXCLUSIVE) == 0) { 533 printf("shared lock of (%s) %s @ %s:%d\n", 534 class->lc_name, lock->lo_name, file, line); 535 printf("while exclusively locked from %s:%d\n", 536 lock1->li_file, lock1->li_line); 537 panic("share->excl"); 538 } 539 if ((lock1->li_flags & LI_EXCLUSIVE) == 0 && 540 (flags & LOP_EXCLUSIVE) != 0) { 541 printf("exclusive lock of (%s) %s @ %s:%d\n", 542 class->lc_name, lock->lo_name, file, line); 543 printf("while share locked from %s:%d\n", 544 lock1->li_file, lock1->li_line); 545 panic("excl->share"); 546 } 547 lock1->li_flags++; 548 if ((lock->lo_flags & LO_RECURSABLE) == 0) { 549 printf( 550 "recursed on non-recursive lock (%s) %s @ %s:%d\n", 551 class->lc_name, lock->lo_name, file, line); 552 printf("first acquired @ %s:%d\n", lock1->li_file, 553 lock1->li_line); 554 panic("recurse"); 555 } 556 CTR4(KTR_WITNESS, "%s: pid %d recursed on %s r=%d", __func__, 557 td->td_proc->p_pid, lock->lo_name, 558 lock1->li_flags & LI_RECURSEMASK); 559 lock1->li_file = file; 560 lock1->li_line = line; 561 return; 562 } 563 564 /* 565 * Check for duplicate locks of the same type. Note that we only 566 * have to check for this on the last lock we just acquired. Any 567 * other cases will be caught as lock order violations. 568 */ 569 lock1 = &(*lock_list)->ll_children[(*lock_list)->ll_count - 1]; 570 w1 = lock1->li_lock->lo_witness; 571 if (w1 == w) { 572 if (w->w_same_squawked || (lock->lo_flags & LO_DUPOK)) 573 goto out; 574 w->w_same_squawked = 1; 575 printf("acquiring duplicate lock of same type: \"%s\"\n", 576 lock->lo_type); 577 printf(" 1st %s @ %s:%d\n", lock1->li_lock->lo_name, 578 lock1->li_file, lock1->li_line); 579 printf(" 2nd %s @ %s:%d\n", lock->lo_name, file, line); 580 #ifdef DDB 581 go_into_ddb = 1; 582 #endif /* DDB */ 583 goto out; 584 } 585 MPASS(!mtx_owned(&w_mtx)); 586 mtx_lock_spin(&w_mtx); 587 /* 588 * If we have a known higher number just say ok 589 */ 590 if (witness_watch > 1 && w->w_level > w1->w_level) { 591 mtx_unlock_spin(&w_mtx); 592 goto out; 593 } 594 if (isitmydescendant(w1, w)) { 595 mtx_unlock_spin(&w_mtx); 596 goto out; 597 } 598 for (j = 0, lle = *lock_list; lle != NULL; lle = lle->ll_next) { 599 for (i = lle->ll_count - 1; i >= 0; i--, j++) { 600 601 MPASS(j < WITNESS_COUNT); 602 lock1 = &lle->ll_children[i]; 603 w1 = lock1->li_lock->lo_witness; 604 605 /* 606 * If this lock doesn't undergo witness checking, 607 * then skip it. 608 */ 609 if (w1 == NULL) { 610 KASSERT((lock1->li_lock->lo_flags & LO_WITNESS) == 0, 611 ("lock missing witness structure")); 612 continue; 613 } 614 /* 615 * If we are locking Giant and we slept with this 616 * lock, then skip it. 617 */ 618 if ((lock1->li_flags & LI_SLEPT) != 0 && 619 lock == &Giant.mtx_object) 620 continue; 621 /* 622 * If we are locking a sleepable lock and this lock 623 * isn't sleepable and isn't Giant, we want to treat 624 * it as a lock order violation to enfore a general 625 * lock order of sleepable locks before non-sleepable 626 * locks. Thus, we only bother checking the lock 627 * order hierarchy if we pass the initial test. 628 */ 629 if (!((lock->lo_flags & LO_SLEEPABLE) != 0 && 630 ((lock1->li_lock->lo_flags & LO_SLEEPABLE) == 0 && 631 lock1->li_lock != &Giant.mtx_object)) && 632 !isitmydescendant(w, w1)) 633 continue; 634 /* 635 * We have a lock order violation, check to see if it 636 * is allowed or has already been yelled about. 637 */ 638 mtx_unlock_spin(&w_mtx); 639 #ifdef BLESSING 640 if (blessed(w, w1)) 641 goto out; 642 #endif 643 if (lock1->li_lock == &Giant.mtx_object) { 644 if (w1->w_Giant_squawked) 645 goto out; 646 else 647 w1->w_Giant_squawked = 1; 648 } else { 649 if (w1->w_other_squawked) 650 goto out; 651 else 652 w1->w_other_squawked = 1; 653 } 654 /* 655 * Ok, yell about it. 656 */ 657 printf("lock order reversal\n"); 658 /* 659 * Try to locate an earlier lock with 660 * witness w in our list. 661 */ 662 do { 663 lock2 = &lle->ll_children[i]; 664 MPASS(lock2->li_lock != NULL); 665 if (lock2->li_lock->lo_witness == w) 666 break; 667 i--; 668 if (i == 0 && lle->ll_next != NULL) { 669 lle = lle->ll_next; 670 i = lle->ll_count - 1; 671 MPASS(i >= 0 && i < LOCK_NCHILDREN); 672 } 673 } while (i >= 0); 674 if (i < 0) { 675 printf(" 1st %p %s (%s) @ %s:%d\n", 676 lock1->li_lock, lock1->li_lock->lo_name, 677 lock1->li_lock->lo_type, lock1->li_file, 678 lock1->li_line); 679 printf(" 2nd %p %s (%s) @ %s:%d\n", lock, 680 lock->lo_name, lock->lo_type, file, line); 681 } else { 682 printf(" 1st %p %s (%s) @ %s:%d\n", 683 lock2->li_lock, lock2->li_lock->lo_name, 684 lock2->li_lock->lo_type, lock2->li_file, 685 lock2->li_line); 686 printf(" 2nd %p %s (%s) @ %s:%d\n", 687 lock1->li_lock, lock1->li_lock->lo_name, 688 lock1->li_lock->lo_type, lock1->li_file, 689 lock1->li_line); 690 printf(" 3rd %p %s (%s) @ %s:%d\n", lock, 691 lock->lo_name, lock->lo_type, file, line); 692 } 693 #ifdef DDB 694 go_into_ddb = 1; 695 #endif /* DDB */ 696 goto out; 697 } 698 } 699 lock1 = &(*lock_list)->ll_children[(*lock_list)->ll_count - 1]; 700 /* 701 * Don't build a new relationship if we are locking Giant just 702 * after waking up and the previous lock in the list was acquired 703 * prior to blocking. 704 */ 705 if (lock == &Giant.mtx_object && (lock1->li_flags & LI_SLEPT) != 0) 706 mtx_unlock_spin(&w_mtx); 707 else { 708 CTR3(KTR_WITNESS, "%s: adding %s as a child of %s", __func__, 709 lock->lo_type, lock1->li_lock->lo_type); 710 if (!itismychild(lock1->li_lock->lo_witness, w)) 711 mtx_unlock_spin(&w_mtx); 712 } 713 714 out: 715 #ifdef DDB 716 if (witness_ddb && go_into_ddb) 717 Debugger(__func__); 718 #endif /* DDB */ 719 w->w_file = file; 720 w->w_line = line; 721 722 lle = *lock_list; 723 if (lle == NULL || lle->ll_count == LOCK_NCHILDREN) { 724 lle = witness_lock_list_get(); 725 if (lle == NULL) 726 return; 727 lle->ll_next = *lock_list; 728 CTR3(KTR_WITNESS, "%s: pid %d added lle %p", __func__, 729 td->td_proc->p_pid, lle); 730 *lock_list = lle; 731 } 732 lock1 = &lle->ll_children[lle->ll_count++]; 733 lock1->li_lock = lock; 734 lock1->li_line = line; 735 lock1->li_file = file; 736 if ((flags & LOP_EXCLUSIVE) != 0) 737 lock1->li_flags = LI_EXCLUSIVE; 738 else 739 lock1->li_flags = 0; 740 CTR4(KTR_WITNESS, "%s: pid %d added %s as lle[%d]", __func__, 741 td->td_proc->p_pid, lock->lo_name, lle->ll_count - 1); 742 } 743 744 void 745 witness_upgrade(struct lock_object *lock, int flags, const char *file, int line) 746 { 747 struct lock_instance *instance; 748 struct lock_class *class; 749 750 KASSERT(!witness_cold, ("%s: witness_cold", __func__)); 751 if (lock->lo_witness == NULL || witness_dead || panicstr != NULL) 752 return; 753 class = lock->lo_class; 754 if ((lock->lo_flags & LO_UPGRADABLE) == 0) 755 panic("upgrade of non-upgradable lock (%s) %s @ %s:%d", 756 class->lc_name, lock->lo_name, file, line); 757 if ((flags & LOP_TRYLOCK) == 0) 758 panic("non-try upgrade of lock (%s) %s @ %s:%d", class->lc_name, 759 lock->lo_name, file, line); 760 if ((lock->lo_class->lc_flags & LC_SLEEPLOCK) == 0) 761 panic("upgrade of non-sleep lock (%s) %s @ %s:%d", 762 class->lc_name, lock->lo_name, file, line); 763 instance = find_instance(curthread->td_sleeplocks, lock); 764 if (instance == NULL) 765 panic("upgrade of unlocked lock (%s) %s @ %s:%d", 766 class->lc_name, lock->lo_name, file, line); 767 if ((instance->li_flags & LI_EXCLUSIVE) != 0) 768 panic("upgrade of exclusive lock (%s) %s @ %s:%d", 769 class->lc_name, lock->lo_name, file, line); 770 if ((instance->li_flags & LI_RECURSEMASK) != 0) 771 panic("upgrade of recursed lock (%s) %s r=%d @ %s:%d", 772 class->lc_name, lock->lo_name, 773 instance->li_flags & LI_RECURSEMASK, file, line); 774 instance->li_flags |= LI_EXCLUSIVE; 775 } 776 777 void 778 witness_downgrade(struct lock_object *lock, int flags, const char *file, 779 int line) 780 { 781 struct lock_instance *instance; 782 struct lock_class *class; 783 784 KASSERT(!witness_cold, ("%s: witness_cold", __func__)); 785 if (lock->lo_witness == NULL || witness_dead || panicstr != NULL) 786 return; 787 class = lock->lo_class; 788 if ((lock->lo_flags & LO_UPGRADABLE) == 0) 789 panic("downgrade of non-upgradable lock (%s) %s @ %s:%d", 790 class->lc_name, lock->lo_name, file, line); 791 if ((lock->lo_class->lc_flags & LC_SLEEPLOCK) == 0) 792 panic("downgrade of non-sleep lock (%s) %s @ %s:%d", 793 class->lc_name, lock->lo_name, file, line); 794 instance = find_instance(curthread->td_sleeplocks, lock); 795 if (instance == NULL) 796 panic("downgrade of unlocked lock (%s) %s @ %s:%d", 797 class->lc_name, lock->lo_name, file, line); 798 if ((instance->li_flags & LI_EXCLUSIVE) == 0) 799 panic("downgrade of shared lock (%s) %s @ %s:%d", 800 class->lc_name, lock->lo_name, file, line); 801 if ((instance->li_flags & LI_RECURSEMASK) != 0) 802 panic("downgrade of recursed lock (%s) %s r=%d @ %s:%d", 803 class->lc_name, lock->lo_name, 804 instance->li_flags & LI_RECURSEMASK, file, line); 805 instance->li_flags &= ~LI_EXCLUSIVE; 806 } 807 808 void 809 witness_unlock(struct lock_object *lock, int flags, const char *file, int line) 810 { 811 struct lock_list_entry **lock_list, *lle; 812 struct lock_instance *instance; 813 struct lock_class *class; 814 struct thread *td; 815 register_t s; 816 int i, j; 817 818 if (witness_cold || witness_dead || lock->lo_witness == NULL || 819 panicstr != NULL) 820 return; 821 td = curthread; 822 class = lock->lo_class; 823 if (class->lc_flags & LC_SLEEPLOCK) 824 lock_list = &td->td_sleeplocks; 825 else 826 lock_list = PCPU_PTR(spinlocks); 827 for (; *lock_list != NULL; lock_list = &(*lock_list)->ll_next) 828 for (i = 0; i < (*lock_list)->ll_count; i++) { 829 instance = &(*lock_list)->ll_children[i]; 830 if (instance->li_lock == lock) { 831 if ((instance->li_flags & LI_EXCLUSIVE) != 0 && 832 (flags & LOP_EXCLUSIVE) == 0) { 833 printf( 834 "shared unlock of (%s) %s @ %s:%d\n", 835 class->lc_name, lock->lo_name, 836 file, line); 837 printf( 838 "while exclusively locked from %s:%d\n", 839 instance->li_file, 840 instance->li_line); 841 panic("excl->ushare"); 842 } 843 if ((instance->li_flags & LI_EXCLUSIVE) == 0 && 844 (flags & LOP_EXCLUSIVE) != 0) { 845 printf( 846 "exclusive unlock of (%s) %s @ %s:%d\n", 847 class->lc_name, lock->lo_name, 848 file, line); 849 printf( 850 "while share locked from %s:%d\n", 851 instance->li_file, 852 instance->li_line); 853 panic("share->uexcl"); 854 } 855 /* If we are recursed, unrecurse. */ 856 if ((instance->li_flags & LI_RECURSEMASK) > 0) { 857 CTR4(KTR_WITNESS, 858 "%s: pid %d unrecursed on %s r=%d", __func__, 859 td->td_proc->p_pid, 860 instance->li_lock->lo_name, 861 instance->li_flags); 862 instance->li_flags--; 863 return; 864 } 865 s = intr_disable(); 866 CTR4(KTR_WITNESS, 867 "%s: pid %d removed %s from lle[%d]", __func__, 868 td->td_proc->p_pid, 869 instance->li_lock->lo_name, 870 (*lock_list)->ll_count - 1); 871 for (j = i; j < (*lock_list)->ll_count - 1; j++) 872 (*lock_list)->ll_children[j] = 873 (*lock_list)->ll_children[j + 1]; 874 (*lock_list)->ll_count--; 875 intr_restore(s); 876 if ((*lock_list)->ll_count == 0) { 877 lle = *lock_list; 878 *lock_list = lle->ll_next; 879 CTR3(KTR_WITNESS, 880 "%s: pid %d removed lle %p", __func__, 881 td->td_proc->p_pid, lle); 882 witness_lock_list_free(lle); 883 } 884 return; 885 } 886 } 887 panic("lock (%s) %s not locked @ %s:%d", class->lc_name, lock->lo_name, 888 file, line); 889 } 890 891 /* 892 * Warn if any held locks are not sleepable. Note that Giant and the lock 893 * passed in are both special cases since they are both released during the 894 * sleep process and aren't actually held while the thread is asleep. 895 */ 896 int 897 witness_sleep(int check_only, struct lock_object *lock, const char *file, 898 int line) 899 { 900 struct lock_list_entry **lock_list, *lle; 901 struct lock_instance *lock1; 902 struct thread *td; 903 int i, n; 904 905 if (witness_cold || witness_dead || panicstr != NULL) 906 return (0); 907 n = 0; 908 td = curthread; 909 lock_list = &td->td_sleeplocks; 910 again: 911 for (lle = *lock_list; lle != NULL; lle = lle->ll_next) 912 for (i = lle->ll_count - 1; i >= 0; i--) { 913 lock1 = &lle->ll_children[i]; 914 if (lock1->li_lock == lock || 915 lock1->li_lock == &Giant.mtx_object) 916 continue; 917 if ((lock1->li_lock->lo_flags & LO_SLEEPABLE) != 0) { 918 if (check_only == 0) { 919 CTR3(KTR_WITNESS, 920 "pid %d: sleeping with lock (%s) %s held", 921 td->td_proc->p_pid, 922 lock1->li_lock->lo_class->lc_name, 923 lock1->li_lock->lo_name); 924 lock1->li_flags |= LI_SLEPT; 925 } 926 continue; 927 } 928 n++; 929 printf("%s:%d: %s with \"%s\" locked from %s:%d\n", 930 file, line, check_only ? "could sleep" : "sleeping", 931 lock1->li_lock->lo_name, lock1->li_file, 932 lock1->li_line); 933 } 934 if (lock_list == &td->td_sleeplocks && PCPU_GET(spinlocks) != NULL) { 935 /* 936 * Since we already hold a spinlock preemption is 937 * already blocked. 938 */ 939 lock_list = PCPU_PTR(spinlocks); 940 goto again; 941 } 942 #ifdef DDB 943 if (witness_ddb && n) 944 Debugger(__func__); 945 #endif /* DDB */ 946 return (n); 947 } 948 949 const char * 950 witness_file(struct lock_object *lock) 951 { 952 struct witness *w; 953 954 if (witness_cold || witness_dead || lock->lo_witness == NULL) 955 return ("?"); 956 w = lock->lo_witness; 957 return (w->w_file); 958 } 959 960 int 961 witness_line(struct lock_object *lock) 962 { 963 struct witness *w; 964 965 if (witness_cold || witness_dead || lock->lo_witness == NULL) 966 return (0); 967 w = lock->lo_witness; 968 return (w->w_line); 969 } 970 971 static struct witness * 972 enroll(const char *description, struct lock_class *lock_class) 973 { 974 struct witness *w; 975 976 if (!witness_watch || witness_dead || panicstr != NULL) 977 return (NULL); 978 if ((lock_class->lc_flags & LC_SPINLOCK) && witness_skipspin) 979 return (NULL); 980 mtx_lock_spin(&w_mtx); 981 STAILQ_FOREACH(w, &w_all, w_list) { 982 if (w->w_name == description || (w->w_refcount > 0 && 983 strcmp(description, w->w_name) == 0)) { 984 w->w_refcount++; 985 mtx_unlock_spin(&w_mtx); 986 if (lock_class != w->w_class) 987 panic( 988 "lock (%s) %s does not match earlier (%s) lock", 989 description, lock_class->lc_name, 990 w->w_class->lc_name); 991 return (w); 992 } 993 } 994 /* 995 * This isn't quite right, as witness_cold is still 0 while we 996 * enroll all the locks initialized before witness_initialize(). 997 */ 998 if ((lock_class->lc_flags & LC_SPINLOCK) && !witness_cold) { 999 mtx_unlock_spin(&w_mtx); 1000 panic("spin lock %s not in order list", description); 1001 } 1002 if ((w = witness_get()) == NULL) 1003 return (NULL); 1004 w->w_name = description; 1005 w->w_class = lock_class; 1006 w->w_refcount = 1; 1007 STAILQ_INSERT_HEAD(&w_all, w, w_list); 1008 if (lock_class->lc_flags & LC_SPINLOCK) 1009 STAILQ_INSERT_HEAD(&w_spin, w, w_typelist); 1010 else if (lock_class->lc_flags & LC_SLEEPLOCK) 1011 STAILQ_INSERT_HEAD(&w_sleep, w, w_typelist); 1012 else { 1013 mtx_unlock_spin(&w_mtx); 1014 panic("lock class %s is not sleep or spin", 1015 lock_class->lc_name); 1016 } 1017 mtx_unlock_spin(&w_mtx); 1018 return (w); 1019 } 1020 1021 static int 1022 itismychild(struct witness *parent, struct witness *child) 1023 { 1024 static int recursed; 1025 struct witness_child_list_entry **wcl; 1026 struct witness_list *list; 1027 1028 MPASS(child != NULL && parent != NULL); 1029 if ((parent->w_class->lc_flags & (LC_SLEEPLOCK | LC_SPINLOCK)) != 1030 (child->w_class->lc_flags & (LC_SLEEPLOCK | LC_SPINLOCK))) 1031 panic( 1032 "%s: parent (%s) and child (%s) are not the same lock type", 1033 __func__, parent->w_class->lc_name, 1034 child->w_class->lc_name); 1035 1036 /* 1037 * Insert "child" after "parent" 1038 */ 1039 wcl = &parent->w_children; 1040 while (*wcl != NULL && (*wcl)->wcl_count == WITNESS_NCHILDREN) 1041 wcl = &(*wcl)->wcl_next; 1042 if (*wcl == NULL) { 1043 *wcl = witness_child_get(); 1044 if (*wcl == NULL) 1045 return (1); 1046 } 1047 (*wcl)->wcl_children[(*wcl)->wcl_count++] = child; 1048 1049 /* 1050 * Now prune whole tree. We look for cases where a lock is now 1051 * both a descendant and a direct child of a given lock. In that 1052 * case, we want to remove the direct child link from the tree. 1053 */ 1054 if (recursed) 1055 return (0); 1056 recursed = 1; 1057 if (parent->w_class->lc_flags & LC_SLEEPLOCK) 1058 list = &w_sleep; 1059 else 1060 list = &w_spin; 1061 STAILQ_FOREACH(child, list, w_typelist) { 1062 STAILQ_FOREACH(parent, list, w_typelist) { 1063 if (!isitmychild(parent, child)) 1064 continue; 1065 removechild(parent, child); 1066 if (isitmydescendant(parent, child)) 1067 continue; 1068 itismychild(parent, child); 1069 } 1070 } 1071 recursed = 0; 1072 witness_levelall(); 1073 return (0); 1074 } 1075 1076 static void 1077 removechild(struct witness *parent, struct witness *child) 1078 { 1079 struct witness_child_list_entry **wcl, *wcl1; 1080 int i; 1081 1082 for (wcl = &parent->w_children; *wcl != NULL; wcl = &(*wcl)->wcl_next) 1083 for (i = 0; i < (*wcl)->wcl_count; i++) 1084 if ((*wcl)->wcl_children[i] == child) 1085 goto found; 1086 return; 1087 found: 1088 (*wcl)->wcl_count--; 1089 if ((*wcl)->wcl_count > i) 1090 (*wcl)->wcl_children[i] = 1091 (*wcl)->wcl_children[(*wcl)->wcl_count]; 1092 MPASS((*wcl)->wcl_children[i] != NULL); 1093 if ((*wcl)->wcl_count != 0) 1094 return; 1095 wcl1 = *wcl; 1096 *wcl = wcl1->wcl_next; 1097 witness_child_free(wcl1); 1098 } 1099 1100 static int 1101 isitmychild(struct witness *parent, struct witness *child) 1102 { 1103 struct witness_child_list_entry *wcl; 1104 int i; 1105 1106 for (wcl = parent->w_children; wcl != NULL; wcl = wcl->wcl_next) { 1107 for (i = 0; i < wcl->wcl_count; i++) { 1108 if (wcl->wcl_children[i] == child) 1109 return (1); 1110 } 1111 } 1112 return (0); 1113 } 1114 1115 static int 1116 isitmydescendant(struct witness *parent, struct witness *child) 1117 { 1118 struct witness_child_list_entry *wcl; 1119 int i, j; 1120 1121 if (isitmychild(parent, child)) 1122 return (1); 1123 j = 0; 1124 for (wcl = parent->w_children; wcl != NULL; wcl = wcl->wcl_next) { 1125 MPASS(j < 1000); 1126 for (i = 0; i < wcl->wcl_count; i++) { 1127 if (isitmydescendant(wcl->wcl_children[i], child)) 1128 return (1); 1129 } 1130 j++; 1131 } 1132 return (0); 1133 } 1134 1135 static void 1136 witness_levelall (void) 1137 { 1138 struct witness_list *list; 1139 struct witness *w, *w1; 1140 1141 /* 1142 * First clear all levels. 1143 */ 1144 STAILQ_FOREACH(w, &w_all, w_list) { 1145 w->w_level = 0; 1146 } 1147 1148 /* 1149 * Look for locks with no parent and level all their descendants. 1150 */ 1151 STAILQ_FOREACH(w, &w_all, w_list) { 1152 /* 1153 * This is just an optimization, technically we could get 1154 * away just walking the all list each time. 1155 */ 1156 if (w->w_class->lc_flags & LC_SLEEPLOCK) 1157 list = &w_sleep; 1158 else 1159 list = &w_spin; 1160 STAILQ_FOREACH(w1, list, w_typelist) { 1161 if (isitmychild(w1, w)) 1162 goto skip; 1163 } 1164 witness_leveldescendents(w, 0); 1165 skip: 1166 ; /* silence GCC 3.x */ 1167 } 1168 } 1169 1170 static void 1171 witness_leveldescendents(struct witness *parent, int level) 1172 { 1173 struct witness_child_list_entry *wcl; 1174 int i; 1175 1176 if (parent->w_level < level) 1177 parent->w_level = level; 1178 level++; 1179 for (wcl = parent->w_children; wcl != NULL; wcl = wcl->wcl_next) 1180 for (i = 0; i < wcl->wcl_count; i++) 1181 witness_leveldescendents(wcl->wcl_children[i], level); 1182 } 1183 1184 static void 1185 witness_displaydescendants(void(*prnt)(const char *fmt, ...), 1186 struct witness *parent) 1187 { 1188 struct witness_child_list_entry *wcl; 1189 int i, level; 1190 1191 level = parent->w_level; 1192 prnt("%-2d", level); 1193 for (i = 0; i < level; i++) 1194 prnt(" "); 1195 if (parent->w_refcount > 0) { 1196 prnt("%s", parent->w_name); 1197 if (parent->w_file != NULL) 1198 prnt(" -- last acquired @ %s:%d\n", parent->w_file, 1199 parent->w_line); 1200 } else 1201 prnt("(dead)\n"); 1202 for (wcl = parent->w_children; wcl != NULL; wcl = wcl->wcl_next) 1203 for (i = 0; i < wcl->wcl_count; i++) 1204 witness_displaydescendants(prnt, 1205 wcl->wcl_children[i]); 1206 } 1207 1208 #ifdef BLESSING 1209 static int 1210 blessed(struct witness *w1, struct witness *w2) 1211 { 1212 int i; 1213 struct witness_blessed *b; 1214 1215 for (i = 0; i < blessed_count; i++) { 1216 b = &blessed_list[i]; 1217 if (strcmp(w1->w_name, b->b_lock1) == 0) { 1218 if (strcmp(w2->w_name, b->b_lock2) == 0) 1219 return (1); 1220 continue; 1221 } 1222 if (strcmp(w1->w_name, b->b_lock2) == 0) 1223 if (strcmp(w2->w_name, b->b_lock1) == 0) 1224 return (1); 1225 } 1226 return (0); 1227 } 1228 #endif 1229 1230 static struct witness * 1231 witness_get(void) 1232 { 1233 struct witness *w; 1234 1235 if (witness_dead) { 1236 mtx_unlock_spin(&w_mtx); 1237 return (NULL); 1238 } 1239 if (STAILQ_EMPTY(&w_free)) { 1240 witness_dead = 1; 1241 mtx_unlock_spin(&w_mtx); 1242 printf("%s: witness exhausted\n", __func__); 1243 return (NULL); 1244 } 1245 w = STAILQ_FIRST(&w_free); 1246 STAILQ_REMOVE_HEAD(&w_free, w_list); 1247 bzero(w, sizeof(*w)); 1248 return (w); 1249 } 1250 1251 static void 1252 witness_free(struct witness *w) 1253 { 1254 1255 STAILQ_INSERT_HEAD(&w_free, w, w_list); 1256 } 1257 1258 static struct witness_child_list_entry * 1259 witness_child_get(void) 1260 { 1261 struct witness_child_list_entry *wcl; 1262 1263 if (witness_dead) { 1264 mtx_unlock_spin(&w_mtx); 1265 return (NULL); 1266 } 1267 wcl = w_child_free; 1268 if (wcl == NULL) { 1269 witness_dead = 1; 1270 mtx_unlock_spin(&w_mtx); 1271 printf("%s: witness exhausted\n", __func__); 1272 return (NULL); 1273 } 1274 w_child_free = wcl->wcl_next; 1275 bzero(wcl, sizeof(*wcl)); 1276 return (wcl); 1277 } 1278 1279 static void 1280 witness_child_free(struct witness_child_list_entry *wcl) 1281 { 1282 1283 wcl->wcl_next = w_child_free; 1284 w_child_free = wcl; 1285 } 1286 1287 static struct lock_list_entry * 1288 witness_lock_list_get(void) 1289 { 1290 struct lock_list_entry *lle; 1291 1292 if (witness_dead) 1293 return (NULL); 1294 mtx_lock_spin(&w_mtx); 1295 lle = w_lock_list_free; 1296 if (lle == NULL) { 1297 witness_dead = 1; 1298 mtx_unlock_spin(&w_mtx); 1299 printf("%s: witness exhausted\n", __func__); 1300 return (NULL); 1301 } 1302 w_lock_list_free = lle->ll_next; 1303 mtx_unlock_spin(&w_mtx); 1304 bzero(lle, sizeof(*lle)); 1305 return (lle); 1306 } 1307 1308 static void 1309 witness_lock_list_free(struct lock_list_entry *lle) 1310 { 1311 1312 mtx_lock_spin(&w_mtx); 1313 lle->ll_next = w_lock_list_free; 1314 w_lock_list_free = lle; 1315 mtx_unlock_spin(&w_mtx); 1316 } 1317 1318 static struct lock_instance * 1319 find_instance(struct lock_list_entry *lock_list, struct lock_object *lock) 1320 { 1321 struct lock_list_entry *lle; 1322 struct lock_instance *instance; 1323 int i; 1324 1325 for (lle = lock_list; lle != NULL; lle = lle->ll_next) 1326 for (i = lle->ll_count - 1; i >= 0; i--) { 1327 instance = &lle->ll_children[i]; 1328 if (instance->li_lock == lock) 1329 return (instance); 1330 } 1331 return (NULL); 1332 } 1333 1334 int 1335 witness_list_locks(struct lock_list_entry **lock_list) 1336 { 1337 struct lock_list_entry *lle; 1338 struct lock_instance *instance; 1339 struct lock_object *lock; 1340 int i, nheld; 1341 1342 nheld = 0; 1343 for (lle = *lock_list; lle != NULL; lle = lle->ll_next) 1344 for (i = lle->ll_count - 1; i >= 0; i--) { 1345 instance = &lle->ll_children[i]; 1346 lock = instance->li_lock; 1347 printf("%s %s %s", 1348 (instance->li_flags & LI_EXCLUSIVE) != 0 ? 1349 "exclusive" : "shared", 1350 lock->lo_class->lc_name, lock->lo_name); 1351 if (lock->lo_type != lock->lo_name) 1352 printf(" (%s)", lock->lo_type); 1353 printf(" r = %d (%p) locked @ %s:%d\n", 1354 instance->li_flags & LI_RECURSEMASK, lock, 1355 instance->li_file, instance->li_line); 1356 nheld++; 1357 } 1358 return (nheld); 1359 } 1360 1361 /* 1362 * Calling this on td != curthread is bad unless we are in ddb. 1363 */ 1364 int 1365 witness_list(struct thread *td) 1366 { 1367 int nheld; 1368 1369 KASSERT(!witness_cold, ("%s: witness_cold", __func__)); 1370 #ifdef DDB 1371 KASSERT(td == curthread || db_active, 1372 ("%s: td != curthread and we aren't in the debugger", __func__)); 1373 if (!db_active && witness_dead) 1374 return (0); 1375 #else 1376 KASSERT(td == curthread, ("%s: p != curthread", __func__)); 1377 if (witness_dead) 1378 return (0); 1379 #endif 1380 nheld = witness_list_locks(&td->td_sleeplocks); 1381 1382 /* 1383 * We only handle spinlocks if td == curthread. This is somewhat broken 1384 * if td is currently executing on some other CPU and holds spin locks 1385 * as we won't display those locks. If we had a MI way of getting 1386 * the per-cpu data for a given cpu then we could use 1387 * td->td_kse->ke_oncpu to get the list of spinlocks for this thread 1388 * and "fix" this. 1389 * 1390 * That still wouldn't really fix this unless we locked sched_lock 1391 * or stopped the other CPU to make sure it wasn't changing the list 1392 * out from under us. It is probably best to just not try to handle 1393 * threads on other CPU's for now. 1394 */ 1395 if (td == curthread && PCPU_GET(spinlocks) != NULL) 1396 nheld += witness_list_locks(PCPU_PTR(spinlocks)); 1397 1398 return (nheld); 1399 } 1400 1401 void 1402 witness_save(struct lock_object *lock, const char **filep, int *linep) 1403 { 1404 struct lock_instance *instance; 1405 1406 KASSERT(!witness_cold, ("%s: witness_cold", __func__)); 1407 if (lock->lo_witness == NULL || witness_dead || panicstr != NULL) 1408 return; 1409 if ((lock->lo_class->lc_flags & LC_SLEEPLOCK) == 0) 1410 panic("%s: lock (%s) %s is not a sleep lock", __func__, 1411 lock->lo_class->lc_name, lock->lo_name); 1412 instance = find_instance(curthread->td_sleeplocks, lock); 1413 if (instance == NULL) 1414 panic("%s: lock (%s) %s not locked", __func__, 1415 lock->lo_class->lc_name, lock->lo_name); 1416 *filep = instance->li_file; 1417 *linep = instance->li_line; 1418 } 1419 1420 void 1421 witness_restore(struct lock_object *lock, const char *file, int line) 1422 { 1423 struct lock_instance *instance; 1424 1425 KASSERT(!witness_cold, ("%s: witness_cold", __func__)); 1426 if (lock->lo_witness == NULL || witness_dead || panicstr != NULL) 1427 return; 1428 if ((lock->lo_class->lc_flags & LC_SLEEPLOCK) == 0) 1429 panic("%s: lock (%s) %s is not a sleep lock", __func__, 1430 lock->lo_class->lc_name, lock->lo_name); 1431 instance = find_instance(curthread->td_sleeplocks, lock); 1432 if (instance == NULL) 1433 panic("%s: lock (%s) %s not locked", __func__, 1434 lock->lo_class->lc_name, lock->lo_name); 1435 lock->lo_witness->w_file = file; 1436 lock->lo_witness->w_line = line; 1437 instance->li_file = file; 1438 instance->li_line = line; 1439 } 1440 1441 void 1442 witness_assert(struct lock_object *lock, int flags, const char *file, int line) 1443 { 1444 #ifdef INVARIANT_SUPPORT 1445 struct lock_instance *instance; 1446 1447 if (lock->lo_witness == NULL || witness_dead || panicstr != NULL) 1448 return; 1449 if ((lock->lo_class->lc_flags & LC_SLEEPLOCK) != 0) 1450 instance = find_instance(curthread->td_sleeplocks, lock); 1451 else if ((lock->lo_class->lc_flags & LC_SPINLOCK) != 0) 1452 instance = find_instance(PCPU_GET(spinlocks), lock); 1453 else { 1454 panic("Lock (%s) %s is not sleep or spin!", 1455 lock->lo_class->lc_name, lock->lo_name); 1456 return; 1457 } 1458 switch (flags) { 1459 case LA_UNLOCKED: 1460 if (instance != NULL) 1461 panic("Lock (%s) %s locked @ %s:%d.", 1462 lock->lo_class->lc_name, lock->lo_name, file, line); 1463 break; 1464 case LA_LOCKED: 1465 case LA_LOCKED | LA_RECURSED: 1466 case LA_LOCKED | LA_NOTRECURSED: 1467 case LA_SLOCKED: 1468 case LA_SLOCKED | LA_RECURSED: 1469 case LA_SLOCKED | LA_NOTRECURSED: 1470 case LA_XLOCKED: 1471 case LA_XLOCKED | LA_RECURSED: 1472 case LA_XLOCKED | LA_NOTRECURSED: 1473 if (instance == NULL) { 1474 panic("Lock (%s) %s not locked @ %s:%d.", 1475 lock->lo_class->lc_name, lock->lo_name, file, line); 1476 break; 1477 } 1478 if ((flags & LA_XLOCKED) != 0 && 1479 (instance->li_flags & LI_EXCLUSIVE) == 0) 1480 panic("Lock (%s) %s not exclusively locked @ %s:%d.", 1481 lock->lo_class->lc_name, lock->lo_name, file, line); 1482 if ((flags & LA_SLOCKED) != 0 && 1483 (instance->li_flags & LI_EXCLUSIVE) != 0) 1484 panic("Lock (%s) %s exclusively locked @ %s:%d.", 1485 lock->lo_class->lc_name, lock->lo_name, file, line); 1486 if ((flags & LA_RECURSED) != 0 && 1487 (instance->li_flags & LI_RECURSEMASK) == 0) 1488 panic("Lock (%s) %s not recursed @ %s:%d.", 1489 lock->lo_class->lc_name, lock->lo_name, file, line); 1490 if ((flags & LA_NOTRECURSED) != 0 && 1491 (instance->li_flags & LI_RECURSEMASK) != 0) 1492 panic("Lock (%s) %s recursed @ %s:%d.", 1493 lock->lo_class->lc_name, lock->lo_name, file, line); 1494 break; 1495 default: 1496 panic("Invalid lock assertion at %s:%d.", file, line); 1497 1498 } 1499 #endif /* INVARIANT_SUPPORT */ 1500 } 1501 1502 #ifdef DDB 1503 1504 DB_SHOW_COMMAND(locks, db_witness_list) 1505 { 1506 struct thread *td; 1507 pid_t pid; 1508 struct proc *p; 1509 1510 if (have_addr) { 1511 pid = (addr % 16) + ((addr >> 4) % 16) * 10 + 1512 ((addr >> 8) % 16) * 100 + ((addr >> 12) % 16) * 1000 + 1513 ((addr >> 16) % 16) * 10000; 1514 /* sx_slock(&allproc_lock); */ 1515 FOREACH_PROC_IN_SYSTEM(p) { 1516 if (p->p_pid == pid) 1517 break; 1518 } 1519 /* sx_sunlock(&allproc_lock); */ 1520 if (p == NULL) { 1521 db_printf("pid %d not found\n", pid); 1522 return; 1523 } 1524 FOREACH_THREAD_IN_PROC(p, td) { 1525 witness_list(td); 1526 } 1527 } else { 1528 td = curthread; 1529 witness_list(td); 1530 } 1531 } 1532 1533 DB_SHOW_COMMAND(witness, db_witness_display) 1534 { 1535 1536 witness_display(db_printf); 1537 } 1538 #endif
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