subr_witness.c revision 112117
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: head/sys/kern/subr_witness.c 112117 2003-03-11 22:07:35Z jhb $ 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/* 60 * Special rules concerning Giant and lock orders: 61 * 62 * 1) Giant must be acquired before any other mutexes. Stated another way, 63 * no other mutex may be held when Giant is acquired. 64 * 65 * 2) Giant must be released when blocking on a sleepable lock. 66 * 67 * This rule is less obvious, but is a result of Giant providing the same 68 * semantics as spl(). Basically, when a thread sleeps, it must release 69 * Giant. When a thread blocks on a sleepable lock, it sleeps. Hence rule 70 * 2). 71 * 72 * 3) Giant may be acquired before or after sleepable locks. 73 * 74 * This rule is also not quite as obvious. Giant may be acquired after 75 * a sleepable lock because it is a non-sleepable lock and non-sleepable 76 * locks may always be acquired while holding a sleepable lock. The second 77 * case, Giant before a sleepable lock, follows from rule 2) above. Suppose 78 * you have two threads T1 and T2 and a sleepable lock X. Suppose that T1 79 * acquires X and blocks on Giant. Then suppose that T2 acquires Giant and 80 * blocks on X. When T2 blocks on X, T2 will release Giant allowing T1 to 81 * execute. Thus, acquiring Giant both before and after a sleepable lock 82 * will not result in a lock order reversal. 83 */ 84 85#include "opt_ddb.h" 86#include "opt_witness.h" 87 88#include <sys/param.h> 89#include <sys/bus.h> 90#include <sys/kernel.h> 91#include <sys/ktr.h> 92#include <sys/lock.h> 93#include <sys/malloc.h> 94#include <sys/mutex.h> 95#include <sys/proc.h> 96#include <sys/sysctl.h> 97#include <sys/systm.h> 98 99#include <ddb/ddb.h> 100 101#include <machine/stdarg.h> 102 103/* Define this to check for blessed mutexes */ 104#undef BLESSING 105 106#define WITNESS_COUNT 200 107#define WITNESS_CHILDCOUNT (WITNESS_COUNT * 4) 108/* 109 * XXX: This is somewhat bogus, as we assume here that at most 1024 threads 110 * will hold LOCK_NCHILDREN * 2 locks. We handle failure ok, and we should 111 * probably be safe for the most part, but it's still a SWAG. 112 */ 113#define LOCK_CHILDCOUNT (MAXCPU + 1024) * 2 114 115#define WITNESS_NCHILDREN 6 116 117struct witness_child_list_entry; 118 119struct witness { 120 const char *w_name; 121 struct lock_class *w_class; 122 STAILQ_ENTRY(witness) w_list; /* List of all witnesses. */ 123 STAILQ_ENTRY(witness) w_typelist; /* Witnesses of a type. */ 124 struct witness_child_list_entry *w_children; /* Great evilness... */ 125 const char *w_file; 126 int w_line; 127 u_int w_level; 128 u_int w_refcount; 129 u_char w_Giant_squawked:1; 130 u_char w_other_squawked:1; 131 u_char w_same_squawked:1; 132}; 133 134struct witness_child_list_entry { 135 struct witness_child_list_entry *wcl_next; 136 struct witness *wcl_children[WITNESS_NCHILDREN]; 137 u_int wcl_count; 138}; 139 140STAILQ_HEAD(witness_list, witness); 141 142#ifdef BLESSING 143struct witness_blessed { 144 const char *b_lock1; 145 const char *b_lock2; 146}; 147#endif 148 149struct witness_order_list_entry { 150 const char *w_name; 151 struct lock_class *w_class; 152}; 153 154#ifdef BLESSING 155static int blessed(struct witness *, struct witness *); 156#endif 157static int depart(struct witness *w); 158static struct witness *enroll(const char *description, 159 struct lock_class *lock_class); 160static int insertchild(struct witness *parent, struct witness *child); 161static int isitmychild(struct witness *parent, struct witness *child); 162static int isitmydescendant(struct witness *parent, struct witness *child); 163static int itismychild(struct witness *parent, struct witness *child); 164static int rebalancetree(struct witness_list *list); 165static void removechild(struct witness *parent, struct witness *child); 166static int reparentchildren(struct witness *newparent, 167 struct witness *oldparent); 168static void witness_displaydescendants(void(*)(const char *fmt, ...), 169 struct witness *); 170static const char *fixup_filename(const char *file); 171static void witness_leveldescendents(struct witness *parent, int level); 172static void witness_levelall(void); 173static struct witness *witness_get(void); 174static void witness_free(struct witness *m); 175static struct witness_child_list_entry *witness_child_get(void); 176static void witness_child_free(struct witness_child_list_entry *wcl); 177static struct lock_list_entry *witness_lock_list_get(void); 178static void witness_lock_list_free(struct lock_list_entry *lle); 179static struct lock_instance *find_instance(struct lock_list_entry *lock_list, 180 struct lock_object *lock); 181static void witness_list_lock(struct lock_instance *instance); 182#ifdef DDB 183static void witness_list(struct thread *td); 184static void witness_display_list(void(*prnt)(const char *fmt, ...), 185 struct witness_list *list); 186static void witness_display(void(*)(const char *fmt, ...)); 187#endif 188 189MALLOC_DEFINE(M_WITNESS, "witness", "witness structure"); 190 191static int witness_watch = 1; 192TUNABLE_INT("debug.witness_watch", &witness_watch); 193SYSCTL_INT(_debug, OID_AUTO, witness_watch, CTLFLAG_RD, &witness_watch, 0, ""); 194 195#ifdef DDB 196/* 197 * When DDB is enabled and witness_ddb is set to 1, it will cause the system to 198 * drop into kdebug() when: 199 * - a lock heirarchy violation occurs 200 * - locks are held when going to sleep. 201 */ 202#ifdef WITNESS_DDB 203int witness_ddb = 1; 204#else 205int witness_ddb = 0; 206#endif 207TUNABLE_INT("debug.witness_ddb", &witness_ddb); 208SYSCTL_INT(_debug, OID_AUTO, witness_ddb, CTLFLAG_RW, &witness_ddb, 0, ""); 209 210/* 211 * When DDB is enabled and witness_trace is set to 1, it will cause the system 212 * to print a stack trace: 213 * - a lock heirarchy violation occurs 214 * - locks are held when going to sleep. 215 */ 216int witness_trace = 1; 217TUNABLE_INT("debug.witness_trace", &witness_trace); 218SYSCTL_INT(_debug, OID_AUTO, witness_trace, CTLFLAG_RW, &witness_trace, 0, ""); 219#endif /* DDB */ 220 221#ifdef WITNESS_SKIPSPIN 222int witness_skipspin = 1; 223#else 224int witness_skipspin = 0; 225#endif 226TUNABLE_INT("debug.witness_skipspin", &witness_skipspin); 227SYSCTL_INT(_debug, OID_AUTO, witness_skipspin, CTLFLAG_RD, &witness_skipspin, 0, 228 ""); 229 230static struct mtx w_mtx; 231static struct witness_list w_free = STAILQ_HEAD_INITIALIZER(w_free); 232static struct witness_list w_all = STAILQ_HEAD_INITIALIZER(w_all); 233static struct witness_list w_spin = STAILQ_HEAD_INITIALIZER(w_spin); 234static struct witness_list w_sleep = STAILQ_HEAD_INITIALIZER(w_sleep); 235static struct witness_child_list_entry *w_child_free = NULL; 236static struct lock_list_entry *w_lock_list_free = NULL; 237static int witness_dead; /* fatal error, probably no memory */ 238 239static struct witness w_data[WITNESS_COUNT]; 240static struct witness_child_list_entry w_childdata[WITNESS_CHILDCOUNT]; 241static struct lock_list_entry w_locklistdata[LOCK_CHILDCOUNT]; 242 243static struct witness_order_list_entry order_lists[] = { 244 { "proctree", &lock_class_sx }, 245 { "allproc", &lock_class_sx }, 246 { "Giant", &lock_class_mtx_sleep }, 247 { "filedesc structure", &lock_class_mtx_sleep }, 248 { "pipe mutex", &lock_class_mtx_sleep }, 249 { "sigio lock", &lock_class_mtx_sleep }, 250 { "process group", &lock_class_mtx_sleep }, 251 { "process lock", &lock_class_mtx_sleep }, 252 { "session", &lock_class_mtx_sleep }, 253 { "uidinfo hash", &lock_class_mtx_sleep }, 254 { "uidinfo struct", &lock_class_mtx_sleep }, 255 { NULL, NULL }, 256 /* 257 * spin locks 258 */ 259#ifdef SMP 260 { "ap boot", &lock_class_mtx_spin }, 261#ifdef __i386__ 262 { "com", &lock_class_mtx_spin }, 263#endif 264#endif 265 { "sio", &lock_class_mtx_spin }, 266#ifdef __i386__ 267 { "cy", &lock_class_mtx_spin }, 268#endif 269 { "sabtty", &lock_class_mtx_spin }, 270 { "zstty", &lock_class_mtx_spin }, 271 { "ng_node", &lock_class_mtx_spin }, 272 { "ng_worklist", &lock_class_mtx_spin }, 273 { "ithread table lock", &lock_class_mtx_spin }, 274 { "sched lock", &lock_class_mtx_spin }, 275 { "callout", &lock_class_mtx_spin }, 276 /* 277 * leaf locks 278 */ 279 { "allpmaps", &lock_class_mtx_spin }, 280 { "vm page queue free mutex", &lock_class_mtx_spin }, 281 { "icu", &lock_class_mtx_spin }, 282#ifdef SMP 283 { "smp rendezvous", &lock_class_mtx_spin }, 284#if defined(__i386__) && defined(APIC_IO) 285 { "tlb", &lock_class_mtx_spin }, 286#endif 287#ifdef __sparc64__ 288 { "ipi", &lock_class_mtx_spin }, 289#endif 290#endif 291 { "clk", &lock_class_mtx_spin }, 292 { "mutex profiling lock", &lock_class_mtx_spin }, 293 { "kse zombie lock", &lock_class_mtx_spin }, 294 { "ALD Queue", &lock_class_mtx_spin }, 295#ifdef __ia64__ 296 { "MCA spin lock", &lock_class_mtx_spin }, 297#endif 298#ifdef __i386__ 299 { "pcicfg", &lock_class_mtx_spin }, 300#endif 301 { NULL, NULL }, 302 { NULL, NULL } 303}; 304 305#ifdef BLESSING 306/* 307 * Pairs of locks which have been blessed 308 * Don't complain about order problems with blessed locks 309 */ 310static struct witness_blessed blessed_list[] = { 311}; 312static int blessed_count = 313 sizeof(blessed_list) / sizeof(struct witness_blessed); 314#endif 315 316/* 317 * List of all locks in the system. 318 */ 319TAILQ_HEAD(, lock_object) all_locks = TAILQ_HEAD_INITIALIZER(all_locks); 320 321static struct mtx all_mtx = { 322 { &lock_class_mtx_sleep, /* mtx_object.lo_class */ 323 "All locks list", /* mtx_object.lo_name */ 324 "All locks list", /* mtx_object.lo_type */ 325 LO_INITIALIZED, /* mtx_object.lo_flags */ 326 { NULL, NULL }, /* mtx_object.lo_list */ 327 NULL }, /* mtx_object.lo_witness */ 328 MTX_UNOWNED, 0, /* mtx_lock, mtx_recurse */ 329 TAILQ_HEAD_INITIALIZER(all_mtx.mtx_blocked), 330 { NULL, NULL } /* mtx_contested */ 331}; 332 333/* 334 * This global is set to 0 once it becomes safe to use the witness code. 335 */ 336static int witness_cold = 1; 337 338/* 339 * Global variables for book keeping. 340 */ 341static int lock_cur_cnt; 342static int lock_max_cnt; 343 344/* 345 * The WITNESS-enabled diagnostic code. 346 */ 347static void 348witness_initialize(void *dummy __unused) 349{ 350 struct lock_object *lock; 351 struct witness_order_list_entry *order; 352 struct witness *w, *w1; 353 int i; 354 355 /* 356 * We have to release Giant before initializing its witness 357 * structure so that WITNESS doesn't get confused. 358 */ 359 mtx_unlock(&Giant); 360 mtx_assert(&Giant, MA_NOTOWNED); 361 362 CTR1(KTR_WITNESS, "%s: initializing witness", __func__); 363 TAILQ_INSERT_HEAD(&all_locks, &all_mtx.mtx_object, lo_list); 364 mtx_init(&w_mtx, "witness lock", NULL, MTX_SPIN | MTX_QUIET | 365 MTX_NOWITNESS); 366 for (i = 0; i < WITNESS_COUNT; i++) 367 witness_free(&w_data[i]); 368 for (i = 0; i < WITNESS_CHILDCOUNT; i++) 369 witness_child_free(&w_childdata[i]); 370 for (i = 0; i < LOCK_CHILDCOUNT; i++) 371 witness_lock_list_free(&w_locklistdata[i]); 372 373 /* First add in all the specified order lists. */ 374 for (order = order_lists; order->w_name != NULL; order++) { 375 w = enroll(order->w_name, order->w_class); 376 if (w == NULL) 377 continue; 378 w->w_file = "order list"; 379 for (order++; order->w_name != NULL; order++) { 380 w1 = enroll(order->w_name, order->w_class); 381 if (w1 == NULL) 382 continue; 383 w1->w_file = "order list"; 384 if (!itismychild(w, w1)) 385 panic("Not enough memory for static orders!"); 386 w = w1; 387 } 388 } 389 390 /* Iterate through all locks and add them to witness. */ 391 mtx_lock(&all_mtx); 392 TAILQ_FOREACH(lock, &all_locks, lo_list) { 393 if (lock->lo_flags & LO_WITNESS) 394 lock->lo_witness = enroll(lock->lo_type, 395 lock->lo_class); 396 else 397 lock->lo_witness = NULL; 398 } 399 mtx_unlock(&all_mtx); 400 401 /* Mark the witness code as being ready for use. */ 402 atomic_store_rel_int(&witness_cold, 0); 403 404 mtx_lock(&Giant); 405} 406SYSINIT(witness_init, SI_SUB_WITNESS, SI_ORDER_FIRST, witness_initialize, NULL) 407 408void 409witness_init(struct lock_object *lock) 410{ 411 struct lock_class *class; 412 413 class = lock->lo_class; 414 if (lock->lo_flags & LO_INITIALIZED) 415 panic("%s: lock (%s) %s is already initialized", __func__, 416 class->lc_name, lock->lo_name); 417 if ((lock->lo_flags & LO_RECURSABLE) != 0 && 418 (class->lc_flags & LC_RECURSABLE) == 0) 419 panic("%s: lock (%s) %s can not be recursable", __func__, 420 class->lc_name, lock->lo_name); 421 if ((lock->lo_flags & LO_SLEEPABLE) != 0 && 422 (class->lc_flags & LC_SLEEPABLE) == 0) 423 panic("%s: lock (%s) %s can not be sleepable", __func__, 424 class->lc_name, lock->lo_name); 425 if ((lock->lo_flags & LO_UPGRADABLE) != 0 && 426 (class->lc_flags & LC_UPGRADABLE) == 0) 427 panic("%s: lock (%s) %s can not be upgradable", __func__, 428 class->lc_name, lock->lo_name); 429 430 mtx_lock(&all_mtx); 431 TAILQ_INSERT_TAIL(&all_locks, lock, lo_list); 432 lock->lo_flags |= LO_INITIALIZED; 433 lock_cur_cnt++; 434 if (lock_cur_cnt > lock_max_cnt) 435 lock_max_cnt = lock_cur_cnt; 436 mtx_unlock(&all_mtx); 437 if (!witness_cold && !witness_dead && panicstr == NULL && 438 (lock->lo_flags & LO_WITNESS) != 0) 439 lock->lo_witness = enroll(lock->lo_type, class); 440 else 441 lock->lo_witness = NULL; 442} 443 444void 445witness_destroy(struct lock_object *lock) 446{ 447 struct witness *w; 448 449 if (witness_cold) 450 panic("lock (%s) %s destroyed while witness_cold", 451 lock->lo_class->lc_name, lock->lo_name); 452 if ((lock->lo_flags & LO_INITIALIZED) == 0) 453 panic("%s: lock (%s) %s is not initialized", __func__, 454 lock->lo_class->lc_name, lock->lo_name); 455 456 /* XXX: need to verify that no one holds the lock */ 457 w = lock->lo_witness; 458 if (w != NULL) { 459 mtx_lock_spin(&w_mtx); 460 MPASS(w->w_refcount > 0); 461 w->w_refcount--; 462 463 /* 464 * Lock is already released if we have an allocation failure 465 * and depart() fails. 466 */ 467 if (w->w_refcount != 0 || depart(w)) 468 mtx_unlock_spin(&w_mtx); 469 } 470 471 mtx_lock(&all_mtx); 472 lock_cur_cnt--; 473 TAILQ_REMOVE(&all_locks, lock, lo_list); 474 lock->lo_flags &= ~LO_INITIALIZED; 475 mtx_unlock(&all_mtx); 476} 477 478#ifdef DDB 479static void 480witness_display_list(void(*prnt)(const char *fmt, ...), 481 struct witness_list *list) 482{ 483 struct witness *w, *w1; 484 int found; 485 486 STAILQ_FOREACH(w, list, w_typelist) { 487 if (w->w_file == NULL) 488 continue; 489 found = 0; 490 STAILQ_FOREACH(w1, list, w_typelist) { 491 if (isitmychild(w1, w)) { 492 found++; 493 break; 494 } 495 } 496 if (found) 497 continue; 498 /* 499 * This lock has no anscestors, display its descendants. 500 */ 501 witness_displaydescendants(prnt, w); 502 } 503} 504 505static void 506witness_display(void(*prnt)(const char *fmt, ...)) 507{ 508 struct witness *w; 509 510 KASSERT(!witness_cold, ("%s: witness_cold", __func__)); 511 witness_levelall(); 512 513 /* 514 * First, handle sleep locks which have been acquired at least 515 * once. 516 */ 517 prnt("Sleep locks:\n"); 518 witness_display_list(prnt, &w_sleep); 519 520 /* 521 * Now do spin locks which have been acquired at least once. 522 */ 523 prnt("\nSpin locks:\n"); 524 witness_display_list(prnt, &w_spin); 525 526 /* 527 * Finally, any locks which have not been acquired yet. 528 */ 529 prnt("\nLocks which were never acquired:\n"); 530 STAILQ_FOREACH(w, &w_all, w_list) { 531 if (w->w_file != NULL || w->w_refcount == 0) 532 continue; 533 prnt("%s\n", w->w_name); 534 } 535} 536#endif /* DDB */ 537 538/* Trim useless garbage from filenames. */ 539static const char * 540fixup_filename(const char *file) 541{ 542 543 if (file == NULL) 544 return (NULL); 545 while (strncmp(file, "../", 3) == 0) 546 file += 3; 547 return (file); 548} 549 550void 551witness_lock(struct lock_object *lock, int flags, const char *file, int line) 552{ 553 struct lock_list_entry **lock_list, *lle; 554 struct lock_instance *lock1, *lock2; 555 struct lock_class *class; 556 struct witness *w, *w1; 557 struct thread *td; 558 int i, j; 559#ifdef DDB 560 int go_into_ddb = 0; 561#endif 562 563 if (witness_cold || witness_dead || lock->lo_witness == NULL || 564 panicstr != NULL) 565 return; 566 w = lock->lo_witness; 567 class = lock->lo_class; 568 td = curthread; 569 file = fixup_filename(file); 570 571 if (class->lc_flags & LC_SLEEPLOCK) { 572 /* 573 * Since spin locks include a critical section, this check 574 * impliclty enforces a lock order of all sleep locks before 575 * all spin locks. 576 */ 577 if (td->td_critnest != 0 && (flags & LOP_TRYLOCK) == 0) 578 panic("blockable sleep lock (%s) %s @ %s:%d", 579 class->lc_name, lock->lo_name, file, line); 580 lock_list = &td->td_sleeplocks; 581 } else 582 lock_list = PCPU_PTR(spinlocks); 583 584 /* 585 * Is this the first lock acquired? If so, then no order checking 586 * is needed. 587 */ 588 if (*lock_list == NULL) 589 goto out; 590 591 /* 592 * Check to see if we are recursing on a lock we already own. 593 */ 594 lock1 = find_instance(*lock_list, lock); 595 if (lock1 != NULL) { 596 if ((lock1->li_flags & LI_EXCLUSIVE) != 0 && 597 (flags & LOP_EXCLUSIVE) == 0) { 598 printf("shared lock of (%s) %s @ %s:%d\n", 599 class->lc_name, lock->lo_name, file, line); 600 printf("while exclusively locked from %s:%d\n", 601 lock1->li_file, lock1->li_line); 602 panic("share->excl"); 603 } 604 if ((lock1->li_flags & LI_EXCLUSIVE) == 0 && 605 (flags & LOP_EXCLUSIVE) != 0) { 606 printf("exclusive lock of (%s) %s @ %s:%d\n", 607 class->lc_name, lock->lo_name, file, line); 608 printf("while share locked from %s:%d\n", 609 lock1->li_file, lock1->li_line); 610 panic("excl->share"); 611 } 612 lock1->li_flags++; 613 if ((lock->lo_flags & LO_RECURSABLE) == 0) { 614 printf( 615 "recursed on non-recursive lock (%s) %s @ %s:%d\n", 616 class->lc_name, lock->lo_name, file, line); 617 printf("first acquired @ %s:%d\n", lock1->li_file, 618 lock1->li_line); 619 panic("recurse"); 620 } 621 CTR4(KTR_WITNESS, "%s: pid %d recursed on %s r=%d", __func__, 622 td->td_proc->p_pid, lock->lo_name, 623 lock1->li_flags & LI_RECURSEMASK); 624 lock1->li_file = file; 625 lock1->li_line = line; 626 return; 627 } 628 629 /* 630 * Try locks do not block if they fail to acquire the lock, thus 631 * there is no danger of deadlocks or of switching while holding a 632 * spin lock if we acquire a lock via a try operation. 633 */ 634 if (flags & LOP_TRYLOCK) 635 goto out; 636 637 /* 638 * Check for duplicate locks of the same type. Note that we only 639 * have to check for this on the last lock we just acquired. Any 640 * other cases will be caught as lock order violations. 641 */ 642 lock1 = &(*lock_list)->ll_children[(*lock_list)->ll_count - 1]; 643 w1 = lock1->li_lock->lo_witness; 644 if (w1 == w) { 645 if (w->w_same_squawked || (lock->lo_flags & LO_DUPOK)) 646 goto out; 647 w->w_same_squawked = 1; 648 printf("acquiring duplicate lock of same type: \"%s\"\n", 649 lock->lo_type); 650 printf(" 1st %s @ %s:%d\n", lock1->li_lock->lo_name, 651 lock1->li_file, lock1->li_line); 652 printf(" 2nd %s @ %s:%d\n", lock->lo_name, file, line); 653#ifdef DDB 654 go_into_ddb = 1; 655#endif 656 goto out; 657 } 658 MPASS(!mtx_owned(&w_mtx)); 659 mtx_lock_spin(&w_mtx); 660 /* 661 * If we have a known higher number just say ok 662 */ 663 if (witness_watch > 1 && w->w_level > w1->w_level) { 664 mtx_unlock_spin(&w_mtx); 665 goto out; 666 } 667 /* 668 * If we know that the the lock we are acquiring comes after 669 * the lock we most recently acquired in the lock order tree, 670 * then there is no need for any further checks. 671 */ 672 if (isitmydescendant(w1, w)) { 673 mtx_unlock_spin(&w_mtx); 674 goto out; 675 } 676 for (j = 0, lle = *lock_list; lle != NULL; lle = lle->ll_next) { 677 for (i = lle->ll_count - 1; i >= 0; i--, j++) { 678 679 MPASS(j < WITNESS_COUNT); 680 lock1 = &lle->ll_children[i]; 681 w1 = lock1->li_lock->lo_witness; 682 683 /* 684 * If this lock doesn't undergo witness checking, 685 * then skip it. 686 */ 687 if (w1 == NULL) { 688 KASSERT((lock1->li_lock->lo_flags & LO_WITNESS) == 0, 689 ("lock missing witness structure")); 690 continue; 691 } 692 /* 693 * If we are locking Giant and this is a sleepable 694 * lock, then skip it. 695 */ 696 if ((lock1->li_lock->lo_flags & LO_SLEEPABLE) != 0 && 697 lock == &Giant.mtx_object) 698 continue; 699 /* 700 * If we are locking a sleepable lock and this lock 701 * is Giant, then skip it. 702 */ 703 if ((lock->lo_flags & LO_SLEEPABLE) != 0 && 704 lock1->li_lock == &Giant.mtx_object) 705 continue; 706 /* 707 * If we are locking a sleepable lock and this lock 708 * isn't sleepable, we want to treat it as a lock 709 * order violation to enfore a general lock order of 710 * sleepable locks before non-sleepable locks. 711 */ 712 if (!((lock->lo_flags & LO_SLEEPABLE) != 0 && 713 (lock1->li_lock->lo_flags & LO_SLEEPABLE) == 0)) 714 /* 715 * Check the lock order hierarchy for a reveresal. 716 */ 717 if (!isitmydescendant(w, w1)) 718 continue; 719 /* 720 * We have a lock order violation, check to see if it 721 * is allowed or has already been yelled about. 722 */ 723 mtx_unlock_spin(&w_mtx); 724#ifdef BLESSING 725 if (blessed(w, w1)) 726 goto out; 727#endif 728 if (lock1->li_lock == &Giant.mtx_object) { 729 if (w1->w_Giant_squawked) 730 goto out; 731 else 732 w1->w_Giant_squawked = 1; 733 } else { 734 if (w1->w_other_squawked) 735 goto out; 736 else 737 w1->w_other_squawked = 1; 738 } 739 /* 740 * Ok, yell about it. 741 */ 742 printf("lock order reversal\n"); 743 /* 744 * Try to locate an earlier lock with 745 * witness w in our list. 746 */ 747 do { 748 lock2 = &lle->ll_children[i]; 749 MPASS(lock2->li_lock != NULL); 750 if (lock2->li_lock->lo_witness == w) 751 break; 752 i--; 753 if (i == 0 && lle->ll_next != NULL) { 754 lle = lle->ll_next; 755 i = lle->ll_count - 1; 756 MPASS(i >= 0 && i < LOCK_NCHILDREN); 757 } 758 } while (i >= 0); 759 if (i < 0) { 760 printf(" 1st %p %s (%s) @ %s:%d\n", 761 lock1->li_lock, lock1->li_lock->lo_name, 762 lock1->li_lock->lo_type, lock1->li_file, 763 lock1->li_line); 764 printf(" 2nd %p %s (%s) @ %s:%d\n", lock, 765 lock->lo_name, lock->lo_type, file, line); 766 } else { 767 printf(" 1st %p %s (%s) @ %s:%d\n", 768 lock2->li_lock, lock2->li_lock->lo_name, 769 lock2->li_lock->lo_type, lock2->li_file, 770 lock2->li_line); 771 printf(" 2nd %p %s (%s) @ %s:%d\n", 772 lock1->li_lock, lock1->li_lock->lo_name, 773 lock1->li_lock->lo_type, lock1->li_file, 774 lock1->li_line); 775 printf(" 3rd %p %s (%s) @ %s:%d\n", lock, 776 lock->lo_name, lock->lo_type, file, line); 777 } 778#ifdef DDB 779 go_into_ddb = 1; 780#endif 781 goto out; 782 } 783 } 784 lock1 = &(*lock_list)->ll_children[(*lock_list)->ll_count - 1]; 785 /* 786 * Don't build a new relationship between a sleepable lock and 787 * Giant if it is the wrong direction. The real lock order is that 788 * sleepable locks come before Giant. 789 */ 790 if (!(lock1->li_lock == &Giant.mtx_object && 791 (lock->lo_flags & LO_SLEEPABLE) != 0)) { 792 CTR3(KTR_WITNESS, "%s: adding %s as a child of %s", __func__, 793 lock->lo_type, lock1->li_lock->lo_type); 794 if (!itismychild(lock1->li_lock->lo_witness, w)) 795 /* Witness is dead. */ 796 return; 797 } 798 mtx_unlock_spin(&w_mtx); 799 800out: 801#ifdef DDB 802 if (go_into_ddb) { 803 if (witness_trace) 804 backtrace(); 805 if (witness_ddb) 806 Debugger(__func__); 807 } 808#endif 809 w->w_file = file; 810 w->w_line = line; 811 812 lle = *lock_list; 813 if (lle == NULL || lle->ll_count == LOCK_NCHILDREN) { 814 lle = witness_lock_list_get(); 815 if (lle == NULL) 816 return; 817 lle->ll_next = *lock_list; 818 CTR3(KTR_WITNESS, "%s: pid %d added lle %p", __func__, 819 td->td_proc->p_pid, lle); 820 *lock_list = lle; 821 } 822 lock1 = &lle->ll_children[lle->ll_count++]; 823 lock1->li_lock = lock; 824 lock1->li_line = line; 825 lock1->li_file = file; 826 if ((flags & LOP_EXCLUSIVE) != 0) 827 lock1->li_flags = LI_EXCLUSIVE; 828 else 829 lock1->li_flags = 0; 830 CTR4(KTR_WITNESS, "%s: pid %d added %s as lle[%d]", __func__, 831 td->td_proc->p_pid, lock->lo_name, lle->ll_count - 1); 832} 833 834void 835witness_upgrade(struct lock_object *lock, int flags, const char *file, int line) 836{ 837 struct lock_instance *instance; 838 struct lock_class *class; 839 840 KASSERT(!witness_cold, ("%s: witness_cold", __func__)); 841 if (lock->lo_witness == NULL || witness_dead || panicstr != NULL) 842 return; 843 class = lock->lo_class; 844 file = fixup_filename(file); 845 if ((lock->lo_flags & LO_UPGRADABLE) == 0) 846 panic("upgrade of non-upgradable lock (%s) %s @ %s:%d", 847 class->lc_name, lock->lo_name, file, line); 848 if ((flags & LOP_TRYLOCK) == 0) 849 panic("non-try upgrade of lock (%s) %s @ %s:%d", class->lc_name, 850 lock->lo_name, file, line); 851 if ((lock->lo_class->lc_flags & LC_SLEEPLOCK) == 0) 852 panic("upgrade of non-sleep lock (%s) %s @ %s:%d", 853 class->lc_name, lock->lo_name, file, line); 854 instance = find_instance(curthread->td_sleeplocks, lock); 855 if (instance == NULL) 856 panic("upgrade of unlocked lock (%s) %s @ %s:%d", 857 class->lc_name, lock->lo_name, file, line); 858 if ((instance->li_flags & LI_EXCLUSIVE) != 0) 859 panic("upgrade of exclusive lock (%s) %s @ %s:%d", 860 class->lc_name, lock->lo_name, file, line); 861 if ((instance->li_flags & LI_RECURSEMASK) != 0) 862 panic("upgrade of recursed lock (%s) %s r=%d @ %s:%d", 863 class->lc_name, lock->lo_name, 864 instance->li_flags & LI_RECURSEMASK, file, line); 865 instance->li_flags |= LI_EXCLUSIVE; 866} 867 868void 869witness_downgrade(struct lock_object *lock, int flags, const char *file, 870 int line) 871{ 872 struct lock_instance *instance; 873 struct lock_class *class; 874 875 KASSERT(!witness_cold, ("%s: witness_cold", __func__)); 876 if (lock->lo_witness == NULL || witness_dead || panicstr != NULL) 877 return; 878 class = lock->lo_class; 879 file = fixup_filename(file); 880 if ((lock->lo_flags & LO_UPGRADABLE) == 0) 881 panic("downgrade of non-upgradable lock (%s) %s @ %s:%d", 882 class->lc_name, lock->lo_name, file, line); 883 if ((lock->lo_class->lc_flags & LC_SLEEPLOCK) == 0) 884 panic("downgrade of non-sleep lock (%s) %s @ %s:%d", 885 class->lc_name, lock->lo_name, file, line); 886 instance = find_instance(curthread->td_sleeplocks, lock); 887 if (instance == NULL) 888 panic("downgrade of unlocked lock (%s) %s @ %s:%d", 889 class->lc_name, lock->lo_name, file, line); 890 if ((instance->li_flags & LI_EXCLUSIVE) == 0) 891 panic("downgrade of shared lock (%s) %s @ %s:%d", 892 class->lc_name, lock->lo_name, file, line); 893 if ((instance->li_flags & LI_RECURSEMASK) != 0) 894 panic("downgrade of recursed lock (%s) %s r=%d @ %s:%d", 895 class->lc_name, lock->lo_name, 896 instance->li_flags & LI_RECURSEMASK, file, line); 897 instance->li_flags &= ~LI_EXCLUSIVE; 898} 899 900void 901witness_unlock(struct lock_object *lock, int flags, const char *file, int line) 902{ 903 struct lock_list_entry **lock_list, *lle; 904 struct lock_instance *instance; 905 struct lock_class *class; 906 struct thread *td; 907 register_t s; 908 int i, j; 909 910 if (witness_cold || witness_dead || lock->lo_witness == NULL || 911 panicstr != NULL) 912 return; 913 td = curthread; 914 class = lock->lo_class; 915 file = fixup_filename(file); 916 if (class->lc_flags & LC_SLEEPLOCK) 917 lock_list = &td->td_sleeplocks; 918 else 919 lock_list = PCPU_PTR(spinlocks); 920 for (; *lock_list != NULL; lock_list = &(*lock_list)->ll_next) 921 for (i = 0; i < (*lock_list)->ll_count; i++) { 922 instance = &(*lock_list)->ll_children[i]; 923 if (instance->li_lock == lock) { 924 if ((instance->li_flags & LI_EXCLUSIVE) != 0 && 925 (flags & LOP_EXCLUSIVE) == 0) { 926 printf( 927 "shared unlock of (%s) %s @ %s:%d\n", 928 class->lc_name, lock->lo_name, 929 file, line); 930 printf( 931 "while exclusively locked from %s:%d\n", 932 instance->li_file, 933 instance->li_line); 934 panic("excl->ushare"); 935 } 936 if ((instance->li_flags & LI_EXCLUSIVE) == 0 && 937 (flags & LOP_EXCLUSIVE) != 0) { 938 printf( 939 "exclusive unlock of (%s) %s @ %s:%d\n", 940 class->lc_name, lock->lo_name, 941 file, line); 942 printf( 943 "while share locked from %s:%d\n", 944 instance->li_file, 945 instance->li_line); 946 panic("share->uexcl"); 947 } 948 /* If we are recursed, unrecurse. */ 949 if ((instance->li_flags & LI_RECURSEMASK) > 0) { 950 CTR4(KTR_WITNESS, 951 "%s: pid %d unrecursed on %s r=%d", __func__, 952 td->td_proc->p_pid, 953 instance->li_lock->lo_name, 954 instance->li_flags); 955 instance->li_flags--; 956 return; 957 } 958 s = intr_disable(); 959 CTR4(KTR_WITNESS, 960 "%s: pid %d removed %s from lle[%d]", __func__, 961 td->td_proc->p_pid, 962 instance->li_lock->lo_name, 963 (*lock_list)->ll_count - 1); 964 for (j = i; j < (*lock_list)->ll_count - 1; j++) 965 (*lock_list)->ll_children[j] = 966 (*lock_list)->ll_children[j + 1]; 967 (*lock_list)->ll_count--; 968 intr_restore(s); 969 if ((*lock_list)->ll_count == 0) { 970 lle = *lock_list; 971 *lock_list = lle->ll_next; 972 CTR3(KTR_WITNESS, 973 "%s: pid %d removed lle %p", __func__, 974 td->td_proc->p_pid, lle); 975 witness_lock_list_free(lle); 976 } 977 return; 978 } 979 } 980 panic("lock (%s) %s not locked @ %s:%d", class->lc_name, lock->lo_name, 981 file, line); 982} 983 984/* 985 * Warn if any locks other than 'lock' are held. Flags can be passed in to 986 * exempt Giant and sleepable locks from the checks as well. If any 987 * non-exempt locks are held, then a supplied message is printed to the 988 * console along with a list of the offending locks. If indicated in the 989 * flags then a failure results in a panic as well. 990 */ 991int 992witness_warn(int flags, struct lock_object *lock, const char *fmt, ...) 993{ 994 struct lock_list_entry *lle; 995 struct lock_instance *lock1; 996 struct thread *td; 997 va_list ap; 998 int i, n; 999 1000 if (witness_cold || witness_dead || panicstr != NULL) 1001 return (0); 1002 n = 0; 1003 td = curthread; 1004 for (lle = td->td_sleeplocks; lle != NULL; lle = lle->ll_next) 1005 for (i = lle->ll_count - 1; i >= 0; i--) { 1006 lock1 = &lle->ll_children[i]; 1007 if (lock1->li_lock == lock) 1008 continue; 1009 if (flags & WARN_GIANTOK && 1010 lock1->li_lock == &Giant.mtx_object) 1011 continue; 1012 if (flags & WARN_SLEEPOK && 1013 (lock1->li_lock->lo_flags & LO_SLEEPABLE) != 0) 1014 continue; 1015 if (n == 0) { 1016 va_start(ap, fmt); 1017 vprintf(fmt, ap); 1018 va_end(ap); 1019 printf(" with the following"); 1020 if (flags & WARN_SLEEPOK) 1021 printf(" non-sleepable"); 1022 printf("locks held:\n"); 1023 } 1024 n++; 1025 witness_list_lock(lock1); 1026 } 1027 if (PCPU_GET(spinlocks) != NULL) { 1028 /* 1029 * Since we already hold a spinlock preemption is 1030 * already blocked. 1031 */ 1032 if (n == 0) { 1033 va_start(ap, fmt); 1034 vprintf(fmt, ap); 1035 va_end(ap); 1036 printf(" with the following"); 1037 if (flags & WARN_SLEEPOK) 1038 printf(" non-sleepable"); 1039 printf("locks held:\n"); 1040 } 1041 n += witness_list_locks(PCPU_PTR(spinlocks)); 1042 } 1043 if (flags & WARN_PANIC && n) 1044 panic("witness_warn"); 1045#ifdef DDB 1046 else if (witness_ddb && n) 1047 Debugger(__func__); 1048#endif 1049 return (n); 1050} 1051 1052const char * 1053witness_file(struct lock_object *lock) 1054{ 1055 struct witness *w; 1056 1057 if (witness_cold || witness_dead || lock->lo_witness == NULL) 1058 return ("?"); 1059 w = lock->lo_witness; 1060 return (w->w_file); 1061} 1062 1063int 1064witness_line(struct lock_object *lock) 1065{ 1066 struct witness *w; 1067 1068 if (witness_cold || witness_dead || lock->lo_witness == NULL) 1069 return (0); 1070 w = lock->lo_witness; 1071 return (w->w_line); 1072} 1073 1074static struct witness * 1075enroll(const char *description, struct lock_class *lock_class) 1076{ 1077 struct witness *w; 1078 1079 if (!witness_watch || witness_dead || panicstr != NULL) 1080 return (NULL); 1081 if ((lock_class->lc_flags & LC_SPINLOCK) && witness_skipspin) 1082 return (NULL); 1083 mtx_lock_spin(&w_mtx); 1084 STAILQ_FOREACH(w, &w_all, w_list) { 1085 if (w->w_name == description || (w->w_refcount > 0 && 1086 strcmp(description, w->w_name) == 0)) { 1087 w->w_refcount++; 1088 mtx_unlock_spin(&w_mtx); 1089 if (lock_class != w->w_class) 1090 panic( 1091 "lock (%s) %s does not match earlier (%s) lock", 1092 description, lock_class->lc_name, 1093 w->w_class->lc_name); 1094 return (w); 1095 } 1096 } 1097 /* 1098 * This isn't quite right, as witness_cold is still 0 while we 1099 * enroll all the locks initialized before witness_initialize(). 1100 */ 1101 if ((lock_class->lc_flags & LC_SPINLOCK) && !witness_cold) { 1102 mtx_unlock_spin(&w_mtx); 1103 panic("spin lock %s not in order list", description); 1104 } 1105 if ((w = witness_get()) == NULL) 1106 return (NULL); 1107 w->w_name = description; 1108 w->w_class = lock_class; 1109 w->w_refcount = 1; 1110 STAILQ_INSERT_HEAD(&w_all, w, w_list); 1111 if (lock_class->lc_flags & LC_SPINLOCK) 1112 STAILQ_INSERT_HEAD(&w_spin, w, w_typelist); 1113 else if (lock_class->lc_flags & LC_SLEEPLOCK) 1114 STAILQ_INSERT_HEAD(&w_sleep, w, w_typelist); 1115 else { 1116 mtx_unlock_spin(&w_mtx); 1117 panic("lock class %s is not sleep or spin", 1118 lock_class->lc_name); 1119 } 1120 mtx_unlock_spin(&w_mtx); 1121 return (w); 1122} 1123 1124/* Don't let the door bang you on the way out... */ 1125static int 1126depart(struct witness *w) 1127{ 1128 struct witness_child_list_entry *wcl, *nwcl; 1129 struct witness_list *list; 1130 struct witness *parent; 1131 1132 MPASS(w->w_refcount == 0); 1133 if (w->w_class->lc_flags & LC_SLEEPLOCK) 1134 list = &w_sleep; 1135 else 1136 list = &w_spin; 1137 /* 1138 * First, we run through the entire tree looking for any 1139 * witnesses that the outgoing witness is a child of. For 1140 * each parent that we find, we reparent all the direct 1141 * children of the outgoing witness to its parent. 1142 */ 1143 STAILQ_FOREACH(parent, list, w_typelist) { 1144 if (!isitmychild(parent, w)) 1145 continue; 1146 removechild(parent, w); 1147 if (!reparentchildren(parent, w)) 1148 return (0); 1149 } 1150 1151 /* 1152 * Now we go through and free up the child list of the 1153 * outgoing witness. 1154 */ 1155 for (wcl = w->w_children; wcl != NULL; wcl = nwcl) { 1156 nwcl = wcl->wcl_next; 1157 witness_child_free(wcl); 1158 } 1159 1160 /* 1161 * Detach from various lists and free. 1162 */ 1163 STAILQ_REMOVE(list, w, witness, w_typelist); 1164 STAILQ_REMOVE(&w_all, w, witness, w_list); 1165 witness_free(w); 1166 1167 /* Finally, fixup the tree. */ 1168 return (rebalancetree(list)); 1169} 1170 1171 1172/* 1173 * Prune an entire lock order tree. We look for cases where a lock 1174 * is now both a descendant and a direct child of a given lock. In 1175 * that case, we want to remove the direct child link from the tree. 1176 * 1177 * Returns false if insertchild() fails. 1178 */ 1179static int 1180rebalancetree(struct witness_list *list) 1181{ 1182 struct witness *child, *parent; 1183 1184 STAILQ_FOREACH(child, list, w_typelist) { 1185 STAILQ_FOREACH(parent, list, w_typelist) { 1186 if (!isitmychild(parent, child)) 1187 continue; 1188 removechild(parent, child); 1189 if (isitmydescendant(parent, child)) 1190 continue; 1191 if (!insertchild(parent, child)) 1192 return (0); 1193 } 1194 } 1195 witness_levelall(); 1196 return (1); 1197} 1198 1199/* 1200 * Add "child" as a direct child of "parent". Returns false if 1201 * we fail due to out of memory. 1202 */ 1203static int 1204insertchild(struct witness *parent, struct witness *child) 1205{ 1206 struct witness_child_list_entry **wcl; 1207 1208 MPASS(child != NULL && parent != NULL); 1209 1210 /* 1211 * Insert "child" after "parent" 1212 */ 1213 wcl = &parent->w_children; 1214 while (*wcl != NULL && (*wcl)->wcl_count == WITNESS_NCHILDREN) 1215 wcl = &(*wcl)->wcl_next; 1216 if (*wcl == NULL) { 1217 *wcl = witness_child_get(); 1218 if (*wcl == NULL) 1219 return (0); 1220 } 1221 (*wcl)->wcl_children[(*wcl)->wcl_count++] = child; 1222 1223 return (1); 1224} 1225 1226/* 1227 * Make all the direct descendants of oldparent be direct descendants 1228 * of newparent. 1229 */ 1230static int 1231reparentchildren(struct witness *newparent, struct witness *oldparent) 1232{ 1233 struct witness_child_list_entry *wcl; 1234 int i; 1235 1236 /* Avoid making a witness a child of itself. */ 1237 MPASS(!isitmychild(oldparent, newparent)); 1238 1239 for (wcl = oldparent->w_children; wcl != NULL; wcl = wcl->wcl_next) 1240 for (i = 0; i < wcl->wcl_count; i++) 1241 if (!insertchild(newparent, wcl->wcl_children[i])) 1242 return (0); 1243 return (1); 1244} 1245 1246static int 1247itismychild(struct witness *parent, struct witness *child) 1248{ 1249 struct witness_list *list; 1250 1251 MPASS(child != NULL && parent != NULL); 1252 if ((parent->w_class->lc_flags & (LC_SLEEPLOCK | LC_SPINLOCK)) != 1253 (child->w_class->lc_flags & (LC_SLEEPLOCK | LC_SPINLOCK))) 1254 panic( 1255 "%s: parent (%s) and child (%s) are not the same lock type", 1256 __func__, parent->w_class->lc_name, 1257 child->w_class->lc_name); 1258 1259 if (!insertchild(parent, child)) 1260 return (0); 1261 1262 if (parent->w_class->lc_flags & LC_SLEEPLOCK) 1263 list = &w_sleep; 1264 else 1265 list = &w_spin; 1266 return (rebalancetree(list)); 1267} 1268 1269static void 1270removechild(struct witness *parent, struct witness *child) 1271{ 1272 struct witness_child_list_entry **wcl, *wcl1; 1273 int i; 1274 1275 for (wcl = &parent->w_children; *wcl != NULL; wcl = &(*wcl)->wcl_next) 1276 for (i = 0; i < (*wcl)->wcl_count; i++) 1277 if ((*wcl)->wcl_children[i] == child) 1278 goto found; 1279 return; 1280found: 1281 (*wcl)->wcl_count--; 1282 if ((*wcl)->wcl_count > i) 1283 (*wcl)->wcl_children[i] = 1284 (*wcl)->wcl_children[(*wcl)->wcl_count]; 1285 MPASS((*wcl)->wcl_children[i] != NULL); 1286 if ((*wcl)->wcl_count != 0) 1287 return; 1288 wcl1 = *wcl; 1289 *wcl = wcl1->wcl_next; 1290 witness_child_free(wcl1); 1291} 1292 1293static int 1294isitmychild(struct witness *parent, struct witness *child) 1295{ 1296 struct witness_child_list_entry *wcl; 1297 int i; 1298 1299 for (wcl = parent->w_children; wcl != NULL; wcl = wcl->wcl_next) { 1300 for (i = 0; i < wcl->wcl_count; i++) { 1301 if (wcl->wcl_children[i] == child) 1302 return (1); 1303 } 1304 } 1305 return (0); 1306} 1307 1308static int 1309isitmydescendant(struct witness *parent, struct witness *child) 1310{ 1311 struct witness_child_list_entry *wcl; 1312 int i, j; 1313 1314 if (isitmychild(parent, child)) 1315 return (1); 1316 j = 0; 1317 for (wcl = parent->w_children; wcl != NULL; wcl = wcl->wcl_next) { 1318 MPASS(j < 1000); 1319 for (i = 0; i < wcl->wcl_count; i++) { 1320 if (isitmydescendant(wcl->wcl_children[i], child)) 1321 return (1); 1322 } 1323 j++; 1324 } 1325 return (0); 1326} 1327 1328static void 1329witness_levelall (void) 1330{ 1331 struct witness_list *list; 1332 struct witness *w, *w1; 1333 1334 /* 1335 * First clear all levels. 1336 */ 1337 STAILQ_FOREACH(w, &w_all, w_list) { 1338 w->w_level = 0; 1339 } 1340 1341 /* 1342 * Look for locks with no parent and level all their descendants. 1343 */ 1344 STAILQ_FOREACH(w, &w_all, w_list) { 1345 /* 1346 * This is just an optimization, technically we could get 1347 * away just walking the all list each time. 1348 */ 1349 if (w->w_class->lc_flags & LC_SLEEPLOCK) 1350 list = &w_sleep; 1351 else 1352 list = &w_spin; 1353 STAILQ_FOREACH(w1, list, w_typelist) { 1354 if (isitmychild(w1, w)) 1355 goto skip; 1356 } 1357 witness_leveldescendents(w, 0); 1358 skip: 1359 ; /* silence GCC 3.x */ 1360 } 1361} 1362 1363static void 1364witness_leveldescendents(struct witness *parent, int level) 1365{ 1366 struct witness_child_list_entry *wcl; 1367 int i; 1368 1369 if (parent->w_level < level) 1370 parent->w_level = level; 1371 level++; 1372 for (wcl = parent->w_children; wcl != NULL; wcl = wcl->wcl_next) 1373 for (i = 0; i < wcl->wcl_count; i++) 1374 witness_leveldescendents(wcl->wcl_children[i], level); 1375} 1376 1377static void 1378witness_displaydescendants(void(*prnt)(const char *fmt, ...), 1379 struct witness *parent) 1380{ 1381 struct witness_child_list_entry *wcl; 1382 int i, level; 1383 1384 level = parent->w_level; 1385 prnt("%-2d", level); 1386 for (i = 0; i < level; i++) 1387 prnt(" "); 1388 if (parent->w_refcount > 0) { 1389 prnt("%s", parent->w_name); 1390 if (parent->w_file != NULL) 1391 prnt(" -- last acquired @ %s:%d\n", parent->w_file, 1392 parent->w_line); 1393 } else 1394 prnt("(dead)\n"); 1395 for (wcl = parent->w_children; wcl != NULL; wcl = wcl->wcl_next) 1396 for (i = 0; i < wcl->wcl_count; i++) 1397 witness_displaydescendants(prnt, 1398 wcl->wcl_children[i]); 1399} 1400 1401#ifdef BLESSING 1402static int 1403blessed(struct witness *w1, struct witness *w2) 1404{ 1405 int i; 1406 struct witness_blessed *b; 1407 1408 for (i = 0; i < blessed_count; i++) { 1409 b = &blessed_list[i]; 1410 if (strcmp(w1->w_name, b->b_lock1) == 0) { 1411 if (strcmp(w2->w_name, b->b_lock2) == 0) 1412 return (1); 1413 continue; 1414 } 1415 if (strcmp(w1->w_name, b->b_lock2) == 0) 1416 if (strcmp(w2->w_name, b->b_lock1) == 0) 1417 return (1); 1418 } 1419 return (0); 1420} 1421#endif 1422 1423static struct witness * 1424witness_get(void) 1425{ 1426 struct witness *w; 1427 1428 if (witness_dead) { 1429 mtx_unlock_spin(&w_mtx); 1430 return (NULL); 1431 } 1432 if (STAILQ_EMPTY(&w_free)) { 1433 witness_dead = 1; 1434 mtx_unlock_spin(&w_mtx); 1435 printf("%s: witness exhausted\n", __func__); 1436 return (NULL); 1437 } 1438 w = STAILQ_FIRST(&w_free); 1439 STAILQ_REMOVE_HEAD(&w_free, w_list); 1440 bzero(w, sizeof(*w)); 1441 return (w); 1442} 1443 1444static void 1445witness_free(struct witness *w) 1446{ 1447 1448 STAILQ_INSERT_HEAD(&w_free, w, w_list); 1449} 1450 1451static struct witness_child_list_entry * 1452witness_child_get(void) 1453{ 1454 struct witness_child_list_entry *wcl; 1455 1456 if (witness_dead) { 1457 mtx_unlock_spin(&w_mtx); 1458 return (NULL); 1459 } 1460 wcl = w_child_free; 1461 if (wcl == NULL) { 1462 witness_dead = 1; 1463 mtx_unlock_spin(&w_mtx); 1464 printf("%s: witness exhausted\n", __func__); 1465 return (NULL); 1466 } 1467 w_child_free = wcl->wcl_next; 1468 bzero(wcl, sizeof(*wcl)); 1469 return (wcl); 1470} 1471 1472static void 1473witness_child_free(struct witness_child_list_entry *wcl) 1474{ 1475 1476 wcl->wcl_next = w_child_free; 1477 w_child_free = wcl; 1478} 1479 1480static struct lock_list_entry * 1481witness_lock_list_get(void) 1482{ 1483 struct lock_list_entry *lle; 1484 1485 if (witness_dead) 1486 return (NULL); 1487 mtx_lock_spin(&w_mtx); 1488 lle = w_lock_list_free; 1489 if (lle == NULL) { 1490 witness_dead = 1; 1491 mtx_unlock_spin(&w_mtx); 1492 printf("%s: witness exhausted\n", __func__); 1493 return (NULL); 1494 } 1495 w_lock_list_free = lle->ll_next; 1496 mtx_unlock_spin(&w_mtx); 1497 bzero(lle, sizeof(*lle)); 1498 return (lle); 1499} 1500 1501static void 1502witness_lock_list_free(struct lock_list_entry *lle) 1503{ 1504 1505 mtx_lock_spin(&w_mtx); 1506 lle->ll_next = w_lock_list_free; 1507 w_lock_list_free = lle; 1508 mtx_unlock_spin(&w_mtx); 1509} 1510 1511static struct lock_instance * 1512find_instance(struct lock_list_entry *lock_list, struct lock_object *lock) 1513{ 1514 struct lock_list_entry *lle; 1515 struct lock_instance *instance; 1516 int i; 1517 1518 for (lle = lock_list; lle != NULL; lle = lle->ll_next) 1519 for (i = lle->ll_count - 1; i >= 0; i--) { 1520 instance = &lle->ll_children[i]; 1521 if (instance->li_lock == lock) 1522 return (instance); 1523 } 1524 return (NULL); 1525} 1526 1527static void 1528witness_list_lock(struct lock_instance *instance) 1529{ 1530 struct lock_object *lock; 1531 1532 lock = instance->li_lock; 1533 printf("%s %s %s", (instance->li_flags & LI_EXCLUSIVE) != 0 ? 1534 "exclusive" : "shared", lock->lo_class->lc_name, lock->lo_name); 1535 if (lock->lo_type != lock->lo_name) 1536 printf(" (%s)", lock->lo_type); 1537 printf(" r = %d (%p) locked @ %s:%d\n", 1538 instance->li_flags & LI_RECURSEMASK, lock, instance->li_file, 1539 instance->li_line); 1540} 1541 1542int 1543witness_list_locks(struct lock_list_entry **lock_list) 1544{ 1545 struct lock_list_entry *lle; 1546 int i, nheld; 1547 1548 nheld = 0; 1549 for (lle = *lock_list; lle != NULL; lle = lle->ll_next) 1550 for (i = lle->ll_count - 1; i >= 0; i--) { 1551 witness_list_lock(&lle->ll_children[i]); 1552 nheld++; 1553 } 1554 return (nheld); 1555} 1556 1557void 1558witness_save(struct lock_object *lock, const char **filep, int *linep) 1559{ 1560 struct lock_instance *instance; 1561 1562 KASSERT(!witness_cold, ("%s: witness_cold", __func__)); 1563 if (lock->lo_witness == NULL || witness_dead || panicstr != NULL) 1564 return; 1565 if ((lock->lo_class->lc_flags & LC_SLEEPLOCK) == 0) 1566 panic("%s: lock (%s) %s is not a sleep lock", __func__, 1567 lock->lo_class->lc_name, lock->lo_name); 1568 instance = find_instance(curthread->td_sleeplocks, lock); 1569 if (instance == NULL) 1570 panic("%s: lock (%s) %s not locked", __func__, 1571 lock->lo_class->lc_name, lock->lo_name); 1572 *filep = instance->li_file; 1573 *linep = instance->li_line; 1574} 1575 1576void 1577witness_restore(struct lock_object *lock, const char *file, int line) 1578{ 1579 struct lock_instance *instance; 1580 1581 KASSERT(!witness_cold, ("%s: witness_cold", __func__)); 1582 if (lock->lo_witness == NULL || witness_dead || panicstr != NULL) 1583 return; 1584 if ((lock->lo_class->lc_flags & LC_SLEEPLOCK) == 0) 1585 panic("%s: lock (%s) %s is not a sleep lock", __func__, 1586 lock->lo_class->lc_name, lock->lo_name); 1587 instance = find_instance(curthread->td_sleeplocks, lock); 1588 if (instance == NULL) 1589 panic("%s: lock (%s) %s not locked", __func__, 1590 lock->lo_class->lc_name, lock->lo_name); 1591 lock->lo_witness->w_file = file; 1592 lock->lo_witness->w_line = line; 1593 instance->li_file = file; 1594 instance->li_line = line; 1595} 1596 1597void 1598witness_assert(struct lock_object *lock, int flags, const char *file, int line) 1599{ 1600#ifdef INVARIANT_SUPPORT 1601 struct lock_instance *instance; 1602 1603 if (lock->lo_witness == NULL || witness_dead || panicstr != NULL) 1604 return; 1605 if ((lock->lo_class->lc_flags & LC_SLEEPLOCK) != 0) 1606 instance = find_instance(curthread->td_sleeplocks, lock); 1607 else if ((lock->lo_class->lc_flags & LC_SPINLOCK) != 0) 1608 instance = find_instance(PCPU_GET(spinlocks), lock); 1609 else { 1610 panic("Lock (%s) %s is not sleep or spin!", 1611 lock->lo_class->lc_name, lock->lo_name); 1612 return; 1613 } 1614 file = fixup_filename(file); 1615 switch (flags) { 1616 case LA_UNLOCKED: 1617 if (instance != NULL) 1618 panic("Lock (%s) %s locked @ %s:%d.", 1619 lock->lo_class->lc_name, lock->lo_name, file, line); 1620 break; 1621 case LA_LOCKED: 1622 case LA_LOCKED | LA_RECURSED: 1623 case LA_LOCKED | LA_NOTRECURSED: 1624 case LA_SLOCKED: 1625 case LA_SLOCKED | LA_RECURSED: 1626 case LA_SLOCKED | LA_NOTRECURSED: 1627 case LA_XLOCKED: 1628 case LA_XLOCKED | LA_RECURSED: 1629 case LA_XLOCKED | LA_NOTRECURSED: 1630 if (instance == NULL) { 1631 panic("Lock (%s) %s not locked @ %s:%d.", 1632 lock->lo_class->lc_name, lock->lo_name, file, line); 1633 break; 1634 } 1635 if ((flags & LA_XLOCKED) != 0 && 1636 (instance->li_flags & LI_EXCLUSIVE) == 0) 1637 panic("Lock (%s) %s not exclusively locked @ %s:%d.", 1638 lock->lo_class->lc_name, lock->lo_name, file, line); 1639 if ((flags & LA_SLOCKED) != 0 && 1640 (instance->li_flags & LI_EXCLUSIVE) != 0) 1641 panic("Lock (%s) %s exclusively locked @ %s:%d.", 1642 lock->lo_class->lc_name, lock->lo_name, file, line); 1643 if ((flags & LA_RECURSED) != 0 && 1644 (instance->li_flags & LI_RECURSEMASK) == 0) 1645 panic("Lock (%s) %s not recursed @ %s:%d.", 1646 lock->lo_class->lc_name, lock->lo_name, file, line); 1647 if ((flags & LA_NOTRECURSED) != 0 && 1648 (instance->li_flags & LI_RECURSEMASK) != 0) 1649 panic("Lock (%s) %s recursed @ %s:%d.", 1650 lock->lo_class->lc_name, lock->lo_name, file, line); 1651 break; 1652 default: 1653 panic("Invalid lock assertion at %s:%d.", file, line); 1654 1655 } 1656#endif /* INVARIANT_SUPPORT */ 1657} 1658 1659#ifdef DDB 1660static void 1661witness_list(struct thread *td) 1662{ 1663 1664 KASSERT(!witness_cold, ("%s: witness_cold", __func__)); 1665 KASSERT(db_active, ("%s: not in the debugger", __func__)); 1666 1667 if (witness_dead) 1668 return; 1669 1670 witness_list_locks(&td->td_sleeplocks); 1671 1672 /* 1673 * We only handle spinlocks if td == curthread. This is somewhat broken 1674 * if td is currently executing on some other CPU and holds spin locks 1675 * as we won't display those locks. If we had a MI way of getting 1676 * the per-cpu data for a given cpu then we could use 1677 * td->td_kse->ke_oncpu to get the list of spinlocks for this thread 1678 * and "fix" this. 1679 * 1680 * That still wouldn't really fix this unless we locked sched_lock 1681 * or stopped the other CPU to make sure it wasn't changing the list 1682 * out from under us. It is probably best to just not try to handle 1683 * threads on other CPU's for now. 1684 */ 1685 if (td == curthread && PCPU_GET(spinlocks) != NULL) 1686 witness_list_locks(PCPU_PTR(spinlocks)); 1687} 1688 1689DB_SHOW_COMMAND(locks, db_witness_list) 1690{ 1691 struct thread *td; 1692 pid_t pid; 1693 struct proc *p; 1694 1695 if (have_addr) { 1696 pid = (addr % 16) + ((addr >> 4) % 16) * 10 + 1697 ((addr >> 8) % 16) * 100 + ((addr >> 12) % 16) * 1000 + 1698 ((addr >> 16) % 16) * 10000; 1699 /* sx_slock(&allproc_lock); */ 1700 FOREACH_PROC_IN_SYSTEM(p) { 1701 if (p->p_pid == pid) 1702 break; 1703 } 1704 /* sx_sunlock(&allproc_lock); */ 1705 if (p == NULL) { 1706 db_printf("pid %d not found\n", pid); 1707 return; 1708 } 1709 FOREACH_THREAD_IN_PROC(p, td) { 1710 witness_list(td); 1711 } 1712 } else { 1713 td = curthread; 1714 witness_list(td); 1715 } 1716} 1717 1718DB_SHOW_COMMAND(witness, db_witness_display) 1719{ 1720 1721 witness_display(db_printf); 1722} 1723#endif 1724