1 /*- 2 * Copyright (c) 2008 Isilon Systems, Inc. 3 * Copyright (c) 2008 Ilya Maykov <ivmaykov@gmail.com> 4 * Copyright (c) 1998 Berkeley Software Design, Inc. 5 * All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 3. Berkeley Software Design Inc's name may not be used to endorse or 16 * promote products derived from this software without specific prior 17 * written permission. 18 * 19 * THIS SOFTWARE IS PROVIDED BY BERKELEY SOFTWARE DESIGN INC ``AS IS'' AND 20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22 * ARE DISCLAIMED. IN NO EVENT SHALL BERKELEY SOFTWARE DESIGN INC BE LIABLE 23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29 * SUCH DAMAGE. 30 * 31 * from BSDI $Id: mutex_witness.c,v 1.1.2.20 2000/04/27 03:10:27 cp Exp $ 32 * and BSDI $Id: synch_machdep.c,v 2.3.2.39 2000/04/27 03:10:25 cp Exp $ 33 */ 34 35 /* 36 * Implementation of the `witness' lock verifier. Originally implemented for 37 * mutexes in BSD/OS. Extended to handle generic lock objects and lock 38 * classes in FreeBSD. 39 */ 40 41 /* 42 * Main Entry: witness 43 * Pronunciation: 'wit-n&s 44 * Function: noun 45 * Etymology: Middle English witnesse, from Old English witnes knowledge, 46 * testimony, witness, from 2wit 47 * Date: before 12th century 48 * 1 : attestation of a fact or event : TESTIMONY 49 * 2 : one that gives evidence; specifically : one who testifies in 50 * a cause or before a judicial tribunal 51 * 3 : one asked to be present at a transaction so as to be able to 52 * testify to its having taken place 53 * 4 : one who has personal knowledge of something 54 * 5 a : something serving as evidence or proof : SIGN 55 * b : public affirmation by word or example of usually 56 * religious faith or conviction <the heroic witness to divine 57 * life -- Pilot> 58 * 6 capitalized : a member of the Jehovah's Witnesses 59 */ 60 61 /* 62 * Special rules concerning Giant and lock orders: 63 * 64 * 1) Giant must be acquired before any other mutexes. Stated another way, 65 * no other mutex may be held when Giant is acquired. 66 * 67 * 2) Giant must be released when blocking on a sleepable lock. 68 * 69 * This rule is less obvious, but is a result of Giant providing the same 70 * semantics as spl(). Basically, when a thread sleeps, it must release 71 * Giant. When a thread blocks on a sleepable lock, it sleeps. Hence rule 72 * 2). 73 * 74 * 3) Giant may be acquired before or after sleepable locks. 75 * 76 * This rule is also not quite as obvious. Giant may be acquired after 77 * a sleepable lock because it is a non-sleepable lock and non-sleepable 78 * locks may always be acquired while holding a sleepable lock. The second 79 * case, Giant before a sleepable lock, follows from rule 2) above. Suppose 80 * you have two threads T1 and T2 and a sleepable lock X. Suppose that T1 81 * acquires X and blocks on Giant. Then suppose that T2 acquires Giant and 82 * blocks on X. When T2 blocks on X, T2 will release Giant allowing T1 to 83 * execute. Thus, acquiring Giant both before and after a sleepable lock 84 * will not result in a lock order reversal. 85 */ 86 87 #include <sys/cdefs.h> 88 __FBSDID("$FreeBSD$"); 89 90 #include "opt_ddb.h" 91 #include "opt_hwpmc_hooks.h" 92 #include "opt_stack.h" 93 #include "opt_witness.h" 94 95 #include <sys/param.h> 96 #include <sys/bus.h> 97 #include <sys/kdb.h> 98 #include <sys/kernel.h> 99 #include <sys/ktr.h> 100 #include <sys/lock.h> 101 #include <sys/malloc.h> 102 #include <sys/mutex.h> 103 #include <sys/priv.h> 104 #include <sys/proc.h> 105 #include <sys/sbuf.h> 106 #include <sys/sched.h> 107 #include <sys/stack.h> 108 #include <sys/sysctl.h> 109 #include <sys/systm.h> 110 111 #ifdef DDB 112 #include <ddb/ddb.h> 113 #endif 114 115 #include <machine/stdarg.h> 116 117 #if !defined(DDB) && !defined(STACK) 118 #error "DDB or STACK options are required for WITNESS" 119 #endif 120 121 /* Note that these traces do not work with KTR_ALQ. */ 122 #if 0 123 #define KTR_WITNESS KTR_SUBSYS 124 #else 125 #define KTR_WITNESS 0 126 #endif 127 128 #define LI_RECURSEMASK 0x0000ffff /* Recursion depth of lock instance. */ 129 #define LI_EXCLUSIVE 0x00010000 /* Exclusive lock instance. */ 130 #define LI_NORELEASE 0x00020000 /* Lock not allowed to be released. */ 131 132 /* Define this to check for blessed mutexes */ 133 #undef BLESSING 134 135 #ifndef WITNESS_COUNT 136 #define WITNESS_COUNT 1536 137 #endif 138 #define WITNESS_HASH_SIZE 251 /* Prime, gives load factor < 2 */ 139 #define WITNESS_PENDLIST (1024 + MAXCPU) 140 141 /* Allocate 256 KB of stack data space */ 142 #define WITNESS_LO_DATA_COUNT 2048 143 144 /* Prime, gives load factor of ~2 at full load */ 145 #define WITNESS_LO_HASH_SIZE 1021 146 147 /* 148 * XXX: This is somewhat bogus, as we assume here that at most 2048 threads 149 * will hold LOCK_NCHILDREN locks. We handle failure ok, and we should 150 * probably be safe for the most part, but it's still a SWAG. 151 */ 152 #define LOCK_NCHILDREN 5 153 #define LOCK_CHILDCOUNT 2048 154 155 #define MAX_W_NAME 64 156 157 #define FULLGRAPH_SBUF_SIZE 512 158 159 /* 160 * These flags go in the witness relationship matrix and describe the 161 * relationship between any two struct witness objects. 162 */ 163 #define WITNESS_UNRELATED 0x00 /* No lock order relation. */ 164 #define WITNESS_PARENT 0x01 /* Parent, aka direct ancestor. */ 165 #define WITNESS_ANCESTOR 0x02 /* Direct or indirect ancestor. */ 166 #define WITNESS_CHILD 0x04 /* Child, aka direct descendant. */ 167 #define WITNESS_DESCENDANT 0x08 /* Direct or indirect descendant. */ 168 #define WITNESS_ANCESTOR_MASK (WITNESS_PARENT | WITNESS_ANCESTOR) 169 #define WITNESS_DESCENDANT_MASK (WITNESS_CHILD | WITNESS_DESCENDANT) 170 #define WITNESS_RELATED_MASK \ 171 (WITNESS_ANCESTOR_MASK | WITNESS_DESCENDANT_MASK) 172 #define WITNESS_REVERSAL 0x10 /* A lock order reversal has been 173 * observed. */ 174 #define WITNESS_RESERVED1 0x20 /* Unused flag, reserved. */ 175 #define WITNESS_RESERVED2 0x40 /* Unused flag, reserved. */ 176 #define WITNESS_LOCK_ORDER_KNOWN 0x80 /* This lock order is known. */ 177 178 /* Descendant to ancestor flags */ 179 #define WITNESS_DTOA(x) (((x) & WITNESS_RELATED_MASK) >> 2) 180 181 /* Ancestor to descendant flags */ 182 #define WITNESS_ATOD(x) (((x) & WITNESS_RELATED_MASK) << 2) 183 184 #define WITNESS_INDEX_ASSERT(i) \ 185 MPASS((i) > 0 && (i) <= w_max_used_index && (i) < witness_count) 186 187 static MALLOC_DEFINE(M_WITNESS, "Witness", "Witness"); 188 189 /* 190 * Lock instances. A lock instance is the data associated with a lock while 191 * it is held by witness. For example, a lock instance will hold the 192 * recursion count of a lock. Lock instances are held in lists. Spin locks 193 * are held in a per-cpu list while sleep locks are held in per-thread list. 194 */ 195 struct lock_instance { 196 struct lock_object *li_lock; 197 const char *li_file; 198 int li_line; 199 u_int li_flags; 200 }; 201 202 /* 203 * A simple list type used to build the list of locks held by a thread 204 * or CPU. We can't simply embed the list in struct lock_object since a 205 * lock may be held by more than one thread if it is a shared lock. Locks 206 * are added to the head of the list, so we fill up each list entry from 207 * "the back" logically. To ease some of the arithmetic, we actually fill 208 * in each list entry the normal way (children[0] then children[1], etc.) but 209 * when we traverse the list we read children[count-1] as the first entry 210 * down to children[0] as the final entry. 211 */ 212 struct lock_list_entry { 213 struct lock_list_entry *ll_next; 214 struct lock_instance ll_children[LOCK_NCHILDREN]; 215 u_int ll_count; 216 }; 217 218 /* 219 * The main witness structure. One of these per named lock type in the system 220 * (for example, "vnode interlock"). 221 */ 222 struct witness { 223 char w_name[MAX_W_NAME]; 224 uint32_t w_index; /* Index in the relationship matrix */ 225 struct lock_class *w_class; 226 STAILQ_ENTRY(witness) w_list; /* List of all witnesses. */ 227 STAILQ_ENTRY(witness) w_typelist; /* Witnesses of a type. */ 228 struct witness *w_hash_next; /* Linked list in hash buckets. */ 229 const char *w_file; /* File where last acquired */ 230 uint32_t w_line; /* Line where last acquired */ 231 uint32_t w_refcount; 232 uint16_t w_num_ancestors; /* direct/indirect 233 * ancestor count */ 234 uint16_t w_num_descendants; /* direct/indirect 235 * descendant count */ 236 int16_t w_ddb_level; 237 unsigned w_displayed:1; 238 unsigned w_reversed:1; 239 }; 240 241 STAILQ_HEAD(witness_list, witness); 242 243 /* 244 * The witness hash table. Keys are witness names (const char *), elements are 245 * witness objects (struct witness *). 246 */ 247 struct witness_hash { 248 struct witness *wh_array[WITNESS_HASH_SIZE]; 249 uint32_t wh_size; 250 uint32_t wh_count; 251 }; 252 253 /* 254 * Key type for the lock order data hash table. 255 */ 256 struct witness_lock_order_key { 257 uint16_t from; 258 uint16_t to; 259 }; 260 261 struct witness_lock_order_data { 262 struct stack wlod_stack; 263 struct witness_lock_order_key wlod_key; 264 struct witness_lock_order_data *wlod_next; 265 }; 266 267 /* 268 * The witness lock order data hash table. Keys are witness index tuples 269 * (struct witness_lock_order_key), elements are lock order data objects 270 * (struct witness_lock_order_data). 271 */ 272 struct witness_lock_order_hash { 273 struct witness_lock_order_data *wloh_array[WITNESS_LO_HASH_SIZE]; 274 u_int wloh_size; 275 u_int wloh_count; 276 }; 277 278 #ifdef BLESSING 279 struct witness_blessed { 280 const char *b_lock1; 281 const char *b_lock2; 282 }; 283 #endif 284 285 struct witness_pendhelp { 286 const char *wh_type; 287 struct lock_object *wh_lock; 288 }; 289 290 struct witness_order_list_entry { 291 const char *w_name; 292 struct lock_class *w_class; 293 }; 294 295 /* 296 * Returns 0 if one of the locks is a spin lock and the other is not. 297 * Returns 1 otherwise. 298 */ 299 static __inline int 300 witness_lock_type_equal(struct witness *w1, struct witness *w2) 301 { 302 303 return ((w1->w_class->lc_flags & (LC_SLEEPLOCK | LC_SPINLOCK)) == 304 (w2->w_class->lc_flags & (LC_SLEEPLOCK | LC_SPINLOCK))); 305 } 306 307 static __inline int 308 witness_lock_order_key_equal(const struct witness_lock_order_key *a, 309 const struct witness_lock_order_key *b) 310 { 311 312 return (a->from == b->from && a->to == b->to); 313 } 314 315 static int _isitmyx(struct witness *w1, struct witness *w2, int rmask, 316 const char *fname); 317 #ifdef KDB 318 static void _witness_debugger(int cond, const char *msg); 319 #endif 320 static void adopt(struct witness *parent, struct witness *child); 321 #ifdef BLESSING 322 static int blessed(struct witness *, struct witness *); 323 #endif 324 static void depart(struct witness *w); 325 static struct witness *enroll(const char *description, 326 struct lock_class *lock_class); 327 static struct lock_instance *find_instance(struct lock_list_entry *list, 328 const struct lock_object *lock); 329 static int isitmychild(struct witness *parent, struct witness *child); 330 static int isitmydescendant(struct witness *parent, struct witness *child); 331 static void itismychild(struct witness *parent, struct witness *child); 332 static int sysctl_debug_witness_badstacks(SYSCTL_HANDLER_ARGS); 333 static int sysctl_debug_witness_watch(SYSCTL_HANDLER_ARGS); 334 static int sysctl_debug_witness_fullgraph(SYSCTL_HANDLER_ARGS); 335 static void witness_add_fullgraph(struct sbuf *sb, struct witness *parent); 336 #ifdef DDB 337 static void witness_ddb_compute_levels(void); 338 static void witness_ddb_display(int(*)(const char *fmt, ...)); 339 static void witness_ddb_display_descendants(int(*)(const char *fmt, ...), 340 struct witness *, int indent); 341 static void witness_ddb_display_list(int(*prnt)(const char *fmt, ...), 342 struct witness_list *list); 343 static void witness_ddb_level_descendants(struct witness *parent, int l); 344 static void witness_ddb_list(struct thread *td); 345 #endif 346 static void witness_free(struct witness *m); 347 static struct witness *witness_get(void); 348 static uint32_t witness_hash_djb2(const uint8_t *key, uint32_t size); 349 static struct witness *witness_hash_get(const char *key); 350 static void witness_hash_put(struct witness *w); 351 static void witness_init_hash_tables(void); 352 static void witness_increment_graph_generation(void); 353 static void witness_lock_list_free(struct lock_list_entry *lle); 354 static struct lock_list_entry *witness_lock_list_get(void); 355 static int witness_lock_order_add(struct witness *parent, 356 struct witness *child); 357 static int witness_lock_order_check(struct witness *parent, 358 struct witness *child); 359 static struct witness_lock_order_data *witness_lock_order_get( 360 struct witness *parent, 361 struct witness *child); 362 static void witness_list_lock(struct lock_instance *instance, 363 int (*prnt)(const char *fmt, ...)); 364 static void witness_setflag(struct lock_object *lock, int flag, int set); 365 366 #ifdef KDB 367 #define witness_debugger(c) _witness_debugger(c, __func__) 368 #else 369 #define witness_debugger(c) 370 #endif 371 372 static SYSCTL_NODE(_debug, OID_AUTO, witness, CTLFLAG_RW, NULL, 373 "Witness Locking"); 374 375 /* 376 * If set to 0, lock order checking is disabled. If set to -1, 377 * witness is completely disabled. Otherwise witness performs full 378 * lock order checking for all locks. At runtime, lock order checking 379 * may be toggled. However, witness cannot be reenabled once it is 380 * completely disabled. 381 */ 382 static int witness_watch = 1; 383 SYSCTL_PROC(_debug_witness, OID_AUTO, watch, CTLFLAG_RWTUN | CTLTYPE_INT, NULL, 0, 384 sysctl_debug_witness_watch, "I", "witness is watching lock operations"); 385 386 #ifdef KDB 387 /* 388 * When KDB is enabled and witness_kdb is 1, it will cause the system 389 * to drop into kdebug() when: 390 * - a lock hierarchy violation occurs 391 * - locks are held when going to sleep. 392 */ 393 #ifdef WITNESS_KDB 394 int witness_kdb = 1; 395 #else 396 int witness_kdb = 0; 397 #endif 398 SYSCTL_INT(_debug_witness, OID_AUTO, kdb, CTLFLAG_RWTUN, &witness_kdb, 0, ""); 399 400 /* 401 * When KDB is enabled and witness_trace is 1, it will cause the system 402 * to print a stack trace: 403 * - a lock hierarchy violation occurs 404 * - locks are held when going to sleep. 405 */ 406 int witness_trace = 1; 407 SYSCTL_INT(_debug_witness, OID_AUTO, trace, CTLFLAG_RWTUN, &witness_trace, 0, ""); 408 #endif /* KDB */ 409 410 #ifdef WITNESS_SKIPSPIN 411 int witness_skipspin = 1; 412 #else 413 int witness_skipspin = 0; 414 #endif 415 SYSCTL_INT(_debug_witness, OID_AUTO, skipspin, CTLFLAG_RDTUN, &witness_skipspin, 0, ""); 416 417 int badstack_sbuf_size; 418 419 int witness_count = WITNESS_COUNT; 420 SYSCTL_INT(_debug_witness, OID_AUTO, witness_count, CTLFLAG_RDTUN, 421 &witness_count, 0, ""); 422 423 /* 424 * Call this to print out the relations between locks. 425 */ 426 SYSCTL_PROC(_debug_witness, OID_AUTO, fullgraph, CTLTYPE_STRING | CTLFLAG_RD, 427 NULL, 0, sysctl_debug_witness_fullgraph, "A", "Show locks relation graphs"); 428 429 /* 430 * Call this to print out the witness faulty stacks. 431 */ 432 SYSCTL_PROC(_debug_witness, OID_AUTO, badstacks, CTLTYPE_STRING | CTLFLAG_RD, 433 NULL, 0, sysctl_debug_witness_badstacks, "A", "Show bad witness stacks"); 434 435 static struct mtx w_mtx; 436 437 /* w_list */ 438 static struct witness_list w_free = STAILQ_HEAD_INITIALIZER(w_free); 439 static struct witness_list w_all = STAILQ_HEAD_INITIALIZER(w_all); 440 441 /* w_typelist */ 442 static struct witness_list w_spin = STAILQ_HEAD_INITIALIZER(w_spin); 443 static struct witness_list w_sleep = STAILQ_HEAD_INITIALIZER(w_sleep); 444 445 /* lock list */ 446 static struct lock_list_entry *w_lock_list_free = NULL; 447 static struct witness_pendhelp pending_locks[WITNESS_PENDLIST]; 448 static u_int pending_cnt; 449 450 static int w_free_cnt, w_spin_cnt, w_sleep_cnt; 451 SYSCTL_INT(_debug_witness, OID_AUTO, free_cnt, CTLFLAG_RD, &w_free_cnt, 0, ""); 452 SYSCTL_INT(_debug_witness, OID_AUTO, spin_cnt, CTLFLAG_RD, &w_spin_cnt, 0, ""); 453 SYSCTL_INT(_debug_witness, OID_AUTO, sleep_cnt, CTLFLAG_RD, &w_sleep_cnt, 0, 454 ""); 455 456 static struct witness *w_data; 457 static uint8_t **w_rmatrix; 458 static struct lock_list_entry w_locklistdata[LOCK_CHILDCOUNT]; 459 static struct witness_hash w_hash; /* The witness hash table. */ 460 461 /* The lock order data hash */ 462 static struct witness_lock_order_data w_lodata[WITNESS_LO_DATA_COUNT]; 463 static struct witness_lock_order_data *w_lofree = NULL; 464 static struct witness_lock_order_hash w_lohash; 465 static int w_max_used_index = 0; 466 static unsigned int w_generation = 0; 467 static const char w_notrunning[] = "Witness not running\n"; 468 static const char w_stillcold[] = "Witness is still cold\n"; 469 470 471 static struct witness_order_list_entry order_lists[] = { 472 /* 473 * sx locks 474 */ 475 { "proctree", &lock_class_sx }, 476 { "allproc", &lock_class_sx }, 477 { "allprison", &lock_class_sx }, 478 { NULL, NULL }, 479 /* 480 * Various mutexes 481 */ 482 { "Giant", &lock_class_mtx_sleep }, 483 { "pipe mutex", &lock_class_mtx_sleep }, 484 { "sigio lock", &lock_class_mtx_sleep }, 485 { "process group", &lock_class_mtx_sleep }, 486 { "process lock", &lock_class_mtx_sleep }, 487 { "session", &lock_class_mtx_sleep }, 488 { "uidinfo hash", &lock_class_rw }, 489 #ifdef HWPMC_HOOKS 490 { "pmc-sleep", &lock_class_mtx_sleep }, 491 #endif 492 { "time lock", &lock_class_mtx_sleep }, 493 { NULL, NULL }, 494 /* 495 * umtx 496 */ 497 { "umtx lock", &lock_class_mtx_sleep }, 498 { NULL, NULL }, 499 /* 500 * Sockets 501 */ 502 { "accept", &lock_class_mtx_sleep }, 503 { "so_snd", &lock_class_mtx_sleep }, 504 { "so_rcv", &lock_class_mtx_sleep }, 505 { "sellck", &lock_class_mtx_sleep }, 506 { NULL, NULL }, 507 /* 508 * Routing 509 */ 510 { "so_rcv", &lock_class_mtx_sleep }, 511 { "radix node head", &lock_class_rw }, 512 { "rtentry", &lock_class_mtx_sleep }, 513 { "ifaddr", &lock_class_mtx_sleep }, 514 { NULL, NULL }, 515 /* 516 * IPv4 multicast: 517 * protocol locks before interface locks, after UDP locks. 518 */ 519 { "udpinp", &lock_class_rw }, 520 { "in_multi_mtx", &lock_class_mtx_sleep }, 521 { "igmp_mtx", &lock_class_mtx_sleep }, 522 { "if_addr_lock", &lock_class_rw }, 523 { NULL, NULL }, 524 /* 525 * IPv6 multicast: 526 * protocol locks before interface locks, after UDP locks. 527 */ 528 { "udpinp", &lock_class_rw }, 529 { "in6_multi_mtx", &lock_class_mtx_sleep }, 530 { "mld_mtx", &lock_class_mtx_sleep }, 531 { "if_addr_lock", &lock_class_rw }, 532 { NULL, NULL }, 533 /* 534 * UNIX Domain Sockets 535 */ 536 { "unp_link_rwlock", &lock_class_rw }, 537 { "unp_list_lock", &lock_class_mtx_sleep }, 538 { "unp", &lock_class_mtx_sleep }, 539 { "so_snd", &lock_class_mtx_sleep }, 540 { NULL, NULL }, 541 /* 542 * UDP/IP 543 */ 544 { "udp", &lock_class_rw }, 545 { "udpinp", &lock_class_rw }, 546 { "so_snd", &lock_class_mtx_sleep }, 547 { NULL, NULL }, 548 /* 549 * TCP/IP 550 */ 551 { "tcp", &lock_class_rw }, 552 { "tcpinp", &lock_class_rw }, 553 { "so_snd", &lock_class_mtx_sleep }, 554 { NULL, NULL }, 555 /* 556 * BPF 557 */ 558 { "bpf global lock", &lock_class_mtx_sleep }, 559 { "bpf interface lock", &lock_class_rw }, 560 { "bpf cdev lock", &lock_class_mtx_sleep }, 561 { NULL, NULL }, 562 /* 563 * NFS server 564 */ 565 { "nfsd_mtx", &lock_class_mtx_sleep }, 566 { "so_snd", &lock_class_mtx_sleep }, 567 { NULL, NULL }, 568 569 /* 570 * IEEE 802.11 571 */ 572 { "802.11 com lock", &lock_class_mtx_sleep}, 573 { NULL, NULL }, 574 /* 575 * Network drivers 576 */ 577 { "network driver", &lock_class_mtx_sleep}, 578 { NULL, NULL }, 579 580 /* 581 * Netgraph 582 */ 583 { "ng_node", &lock_class_mtx_sleep }, 584 { "ng_worklist", &lock_class_mtx_sleep }, 585 { NULL, NULL }, 586 /* 587 * CDEV 588 */ 589 { "vm map (system)", &lock_class_mtx_sleep }, 590 { "vm page queue", &lock_class_mtx_sleep }, 591 { "vnode interlock", &lock_class_mtx_sleep }, 592 { "cdev", &lock_class_mtx_sleep }, 593 { NULL, NULL }, 594 /* 595 * VM 596 */ 597 { "vm map (user)", &lock_class_sx }, 598 { "vm object", &lock_class_rw }, 599 { "vm page", &lock_class_mtx_sleep }, 600 { "vm page queue", &lock_class_mtx_sleep }, 601 { "pmap pv global", &lock_class_rw }, 602 { "pmap", &lock_class_mtx_sleep }, 603 { "pmap pv list", &lock_class_rw }, 604 { "vm page free queue", &lock_class_mtx_sleep }, 605 { NULL, NULL }, 606 /* 607 * kqueue/VFS interaction 608 */ 609 { "kqueue", &lock_class_mtx_sleep }, 610 { "struct mount mtx", &lock_class_mtx_sleep }, 611 { "vnode interlock", &lock_class_mtx_sleep }, 612 { NULL, NULL }, 613 /* 614 * ZFS locking 615 */ 616 { "dn->dn_mtx", &lock_class_sx }, 617 { "dr->dt.di.dr_mtx", &lock_class_sx }, 618 { "db->db_mtx", &lock_class_sx }, 619 { NULL, NULL }, 620 /* 621 * spin locks 622 */ 623 #ifdef SMP 624 { "ap boot", &lock_class_mtx_spin }, 625 #endif 626 { "rm.mutex_mtx", &lock_class_mtx_spin }, 627 { "sio", &lock_class_mtx_spin }, 628 { "scrlock", &lock_class_mtx_spin }, 629 #ifdef __i386__ 630 { "cy", &lock_class_mtx_spin }, 631 #endif 632 #ifdef __sparc64__ 633 { "pcib_mtx", &lock_class_mtx_spin }, 634 { "rtc_mtx", &lock_class_mtx_spin }, 635 #endif 636 { "scc_hwmtx", &lock_class_mtx_spin }, 637 { "uart_hwmtx", &lock_class_mtx_spin }, 638 { "fast_taskqueue", &lock_class_mtx_spin }, 639 { "intr table", &lock_class_mtx_spin }, 640 #ifdef HWPMC_HOOKS 641 { "pmc-per-proc", &lock_class_mtx_spin }, 642 #endif 643 { "process slock", &lock_class_mtx_spin }, 644 { "sleepq chain", &lock_class_mtx_spin }, 645 { "rm_spinlock", &lock_class_mtx_spin }, 646 { "turnstile chain", &lock_class_mtx_spin }, 647 { "turnstile lock", &lock_class_mtx_spin }, 648 { "sched lock", &lock_class_mtx_spin }, 649 { "td_contested", &lock_class_mtx_spin }, 650 { "callout", &lock_class_mtx_spin }, 651 { "entropy harvest mutex", &lock_class_mtx_spin }, 652 { "syscons video lock", &lock_class_mtx_spin }, 653 #ifdef SMP 654 { "smp rendezvous", &lock_class_mtx_spin }, 655 #endif 656 #ifdef __powerpc__ 657 { "tlb0", &lock_class_mtx_spin }, 658 #endif 659 /* 660 * leaf locks 661 */ 662 { "intrcnt", &lock_class_mtx_spin }, 663 { "icu", &lock_class_mtx_spin }, 664 #if defined(SMP) && defined(__sparc64__) 665 { "ipi", &lock_class_mtx_spin }, 666 #endif 667 #ifdef __i386__ 668 { "allpmaps", &lock_class_mtx_spin }, 669 { "descriptor tables", &lock_class_mtx_spin }, 670 #endif 671 { "clk", &lock_class_mtx_spin }, 672 { "cpuset", &lock_class_mtx_spin }, 673 { "mprof lock", &lock_class_mtx_spin }, 674 { "zombie lock", &lock_class_mtx_spin }, 675 { "ALD Queue", &lock_class_mtx_spin }, 676 #if defined(__i386__) || defined(__amd64__) 677 { "pcicfg", &lock_class_mtx_spin }, 678 { "NDIS thread lock", &lock_class_mtx_spin }, 679 #endif 680 { "tw_osl_io_lock", &lock_class_mtx_spin }, 681 { "tw_osl_q_lock", &lock_class_mtx_spin }, 682 { "tw_cl_io_lock", &lock_class_mtx_spin }, 683 { "tw_cl_intr_lock", &lock_class_mtx_spin }, 684 { "tw_cl_gen_lock", &lock_class_mtx_spin }, 685 #ifdef HWPMC_HOOKS 686 { "pmc-leaf", &lock_class_mtx_spin }, 687 #endif 688 { "blocked lock", &lock_class_mtx_spin }, 689 { NULL, NULL }, 690 { NULL, NULL } 691 }; 692 693 #ifdef BLESSING 694 /* 695 * Pairs of locks which have been blessed 696 * Don't complain about order problems with blessed locks 697 */ 698 static struct witness_blessed blessed_list[] = { 699 }; 700 static int blessed_count = 701 sizeof(blessed_list) / sizeof(struct witness_blessed); 702 #endif 703 704 /* 705 * This global is set to 0 once it becomes safe to use the witness code. 706 */ 707 static int witness_cold = 1; 708 709 /* 710 * This global is set to 1 once the static lock orders have been enrolled 711 * so that a warning can be issued for any spin locks enrolled later. 712 */ 713 static int witness_spin_warn = 0; 714 715 /* Trim useless garbage from filenames. */ 716 static const char * 717 fixup_filename(const char *file) 718 { 719 720 if (file == NULL) 721 return (NULL); 722 while (strncmp(file, "../", 3) == 0) 723 file += 3; 724 return (file); 725 } 726 727 /* 728 * The WITNESS-enabled diagnostic code. Note that the witness code does 729 * assume that the early boot is single-threaded at least until after this 730 * routine is completed. 731 */ 732 static void 733 witness_initialize(void *dummy __unused) 734 { 735 struct lock_object *lock; 736 struct witness_order_list_entry *order; 737 struct witness *w, *w1; 738 int i; 739 740 w_data = malloc(sizeof (struct witness) * witness_count, M_WITNESS, 741 M_WAITOK | M_ZERO); 742 743 w_rmatrix = malloc(sizeof(*w_rmatrix) * (witness_count + 1), 744 M_WITNESS, M_WAITOK | M_ZERO); 745 746 for (i = 0; i < witness_count + 1; i++) { 747 w_rmatrix[i] = malloc(sizeof(*w_rmatrix[i]) * 748 (witness_count + 1), M_WITNESS, M_WAITOK | M_ZERO); 749 } 750 badstack_sbuf_size = witness_count * 256; 751 752 /* 753 * We have to release Giant before initializing its witness 754 * structure so that WITNESS doesn't get confused. 755 */ 756 mtx_unlock(&Giant); 757 mtx_assert(&Giant, MA_NOTOWNED); 758 759 CTR1(KTR_WITNESS, "%s: initializing witness", __func__); 760 mtx_init(&w_mtx, "witness lock", NULL, MTX_SPIN | MTX_QUIET | 761 MTX_NOWITNESS | MTX_NOPROFILE); 762 for (i = witness_count - 1; i >= 0; i--) { 763 w = &w_data[i]; 764 memset(w, 0, sizeof(*w)); 765 w_data[i].w_index = i; /* Witness index never changes. */ 766 witness_free(w); 767 } 768 KASSERT(STAILQ_FIRST(&w_free)->w_index == 0, 769 ("%s: Invalid list of free witness objects", __func__)); 770 771 /* Witness with index 0 is not used to aid in debugging. */ 772 STAILQ_REMOVE_HEAD(&w_free, w_list); 773 w_free_cnt--; 774 775 for (i = 0; i < witness_count; i++) { 776 memset(w_rmatrix[i], 0, sizeof(*w_rmatrix[i]) * 777 (witness_count + 1)); 778 } 779 780 for (i = 0; i < LOCK_CHILDCOUNT; i++) 781 witness_lock_list_free(&w_locklistdata[i]); 782 witness_init_hash_tables(); 783 784 /* First add in all the specified order lists. */ 785 for (order = order_lists; order->w_name != NULL; order++) { 786 w = enroll(order->w_name, order->w_class); 787 if (w == NULL) 788 continue; 789 w->w_file = "order list"; 790 for (order++; order->w_name != NULL; order++) { 791 w1 = enroll(order->w_name, order->w_class); 792 if (w1 == NULL) 793 continue; 794 w1->w_file = "order list"; 795 itismychild(w, w1); 796 w = w1; 797 } 798 } 799 witness_spin_warn = 1; 800 801 /* Iterate through all locks and add them to witness. */ 802 for (i = 0; pending_locks[i].wh_lock != NULL; i++) { 803 lock = pending_locks[i].wh_lock; 804 KASSERT(lock->lo_flags & LO_WITNESS, 805 ("%s: lock %s is on pending list but not LO_WITNESS", 806 __func__, lock->lo_name)); 807 lock->lo_witness = enroll(pending_locks[i].wh_type, 808 LOCK_CLASS(lock)); 809 } 810 811 /* Mark the witness code as being ready for use. */ 812 witness_cold = 0; 813 814 mtx_lock(&Giant); 815 } 816 SYSINIT(witness_init, SI_SUB_WITNESS, SI_ORDER_FIRST, witness_initialize, 817 NULL); 818 819 void 820 witness_init(struct lock_object *lock, const char *type) 821 { 822 struct lock_class *class; 823 824 /* Various sanity checks. */ 825 class = LOCK_CLASS(lock); 826 if ((lock->lo_flags & LO_RECURSABLE) != 0 && 827 (class->lc_flags & LC_RECURSABLE) == 0) 828 kassert_panic("%s: lock (%s) %s can not be recursable", 829 __func__, class->lc_name, lock->lo_name); 830 if ((lock->lo_flags & LO_SLEEPABLE) != 0 && 831 (class->lc_flags & LC_SLEEPABLE) == 0) 832 kassert_panic("%s: lock (%s) %s can not be sleepable", 833 __func__, class->lc_name, lock->lo_name); 834 if ((lock->lo_flags & LO_UPGRADABLE) != 0 && 835 (class->lc_flags & LC_UPGRADABLE) == 0) 836 kassert_panic("%s: lock (%s) %s can not be upgradable", 837 __func__, class->lc_name, lock->lo_name); 838 839 /* 840 * If we shouldn't watch this lock, then just clear lo_witness. 841 * Otherwise, if witness_cold is set, then it is too early to 842 * enroll this lock, so defer it to witness_initialize() by adding 843 * it to the pending_locks list. If it is not too early, then enroll 844 * the lock now. 845 */ 846 if (witness_watch < 1 || panicstr != NULL || 847 (lock->lo_flags & LO_WITNESS) == 0) 848 lock->lo_witness = NULL; 849 else if (witness_cold) { 850 pending_locks[pending_cnt].wh_lock = lock; 851 pending_locks[pending_cnt++].wh_type = type; 852 if (pending_cnt > WITNESS_PENDLIST) 853 panic("%s: pending locks list is too small, " 854 "increase WITNESS_PENDLIST\n", 855 __func__); 856 } else 857 lock->lo_witness = enroll(type, class); 858 } 859 860 void 861 witness_destroy(struct lock_object *lock) 862 { 863 struct lock_class *class; 864 struct witness *w; 865 866 class = LOCK_CLASS(lock); 867 868 if (witness_cold) 869 panic("lock (%s) %s destroyed while witness_cold", 870 class->lc_name, lock->lo_name); 871 872 /* XXX: need to verify that no one holds the lock */ 873 if ((lock->lo_flags & LO_WITNESS) == 0 || lock->lo_witness == NULL) 874 return; 875 w = lock->lo_witness; 876 877 mtx_lock_spin(&w_mtx); 878 MPASS(w->w_refcount > 0); 879 w->w_refcount--; 880 881 if (w->w_refcount == 0) 882 depart(w); 883 mtx_unlock_spin(&w_mtx); 884 } 885 886 #ifdef DDB 887 static void 888 witness_ddb_compute_levels(void) 889 { 890 struct witness *w; 891 892 /* 893 * First clear all levels. 894 */ 895 STAILQ_FOREACH(w, &w_all, w_list) 896 w->w_ddb_level = -1; 897 898 /* 899 * Look for locks with no parents and level all their descendants. 900 */ 901 STAILQ_FOREACH(w, &w_all, w_list) { 902 903 /* If the witness has ancestors (is not a root), skip it. */ 904 if (w->w_num_ancestors > 0) 905 continue; 906 witness_ddb_level_descendants(w, 0); 907 } 908 } 909 910 static void 911 witness_ddb_level_descendants(struct witness *w, int l) 912 { 913 int i; 914 915 if (w->w_ddb_level >= l) 916 return; 917 918 w->w_ddb_level = l; 919 l++; 920 921 for (i = 1; i <= w_max_used_index; i++) { 922 if (w_rmatrix[w->w_index][i] & WITNESS_PARENT) 923 witness_ddb_level_descendants(&w_data[i], l); 924 } 925 } 926 927 static void 928 witness_ddb_display_descendants(int(*prnt)(const char *fmt, ...), 929 struct witness *w, int indent) 930 { 931 int i; 932 933 for (i = 0; i < indent; i++) 934 prnt(" "); 935 prnt("%s (type: %s, depth: %d, active refs: %d)", 936 w->w_name, w->w_class->lc_name, 937 w->w_ddb_level, w->w_refcount); 938 if (w->w_displayed) { 939 prnt(" -- (already displayed)\n"); 940 return; 941 } 942 w->w_displayed = 1; 943 if (w->w_file != NULL && w->w_line != 0) 944 prnt(" -- last acquired @ %s:%d\n", fixup_filename(w->w_file), 945 w->w_line); 946 else 947 prnt(" -- never acquired\n"); 948 indent++; 949 WITNESS_INDEX_ASSERT(w->w_index); 950 for (i = 1; i <= w_max_used_index; i++) { 951 if (db_pager_quit) 952 return; 953 if (w_rmatrix[w->w_index][i] & WITNESS_PARENT) 954 witness_ddb_display_descendants(prnt, &w_data[i], 955 indent); 956 } 957 } 958 959 static void 960 witness_ddb_display_list(int(*prnt)(const char *fmt, ...), 961 struct witness_list *list) 962 { 963 struct witness *w; 964 965 STAILQ_FOREACH(w, list, w_typelist) { 966 if (w->w_file == NULL || w->w_ddb_level > 0) 967 continue; 968 969 /* This lock has no anscestors - display its descendants. */ 970 witness_ddb_display_descendants(prnt, w, 0); 971 if (db_pager_quit) 972 return; 973 } 974 } 975 976 static void 977 witness_ddb_display(int(*prnt)(const char *fmt, ...)) 978 { 979 struct witness *w; 980 981 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); 982 witness_ddb_compute_levels(); 983 984 /* Clear all the displayed flags. */ 985 STAILQ_FOREACH(w, &w_all, w_list) 986 w->w_displayed = 0; 987 988 /* 989 * First, handle sleep locks which have been acquired at least 990 * once. 991 */ 992 prnt("Sleep locks:\n"); 993 witness_ddb_display_list(prnt, &w_sleep); 994 if (db_pager_quit) 995 return; 996 997 /* 998 * Now do spin locks which have been acquired at least once. 999 */ 1000 prnt("\nSpin locks:\n"); 1001 witness_ddb_display_list(prnt, &w_spin); 1002 if (db_pager_quit) 1003 return; 1004 1005 /* 1006 * Finally, any locks which have not been acquired yet. 1007 */ 1008 prnt("\nLocks which were never acquired:\n"); 1009 STAILQ_FOREACH(w, &w_all, w_list) { 1010 if (w->w_file != NULL || w->w_refcount == 0) 1011 continue; 1012 prnt("%s (type: %s, depth: %d)\n", w->w_name, 1013 w->w_class->lc_name, w->w_ddb_level); 1014 if (db_pager_quit) 1015 return; 1016 } 1017 } 1018 #endif /* DDB */ 1019 1020 int 1021 witness_defineorder(struct lock_object *lock1, struct lock_object *lock2) 1022 { 1023 1024 if (witness_watch == -1 || panicstr != NULL) 1025 return (0); 1026 1027 /* Require locks that witness knows about. */ 1028 if (lock1 == NULL || lock1->lo_witness == NULL || lock2 == NULL || 1029 lock2->lo_witness == NULL) 1030 return (EINVAL); 1031 1032 mtx_assert(&w_mtx, MA_NOTOWNED); 1033 mtx_lock_spin(&w_mtx); 1034 1035 /* 1036 * If we already have either an explicit or implied lock order that 1037 * is the other way around, then return an error. 1038 */ 1039 if (witness_watch && 1040 isitmydescendant(lock2->lo_witness, lock1->lo_witness)) { 1041 mtx_unlock_spin(&w_mtx); 1042 return (EDOOFUS); 1043 } 1044 1045 /* Try to add the new order. */ 1046 CTR3(KTR_WITNESS, "%s: adding %s as a child of %s", __func__, 1047 lock2->lo_witness->w_name, lock1->lo_witness->w_name); 1048 itismychild(lock1->lo_witness, lock2->lo_witness); 1049 mtx_unlock_spin(&w_mtx); 1050 return (0); 1051 } 1052 1053 void 1054 witness_checkorder(struct lock_object *lock, int flags, const char *file, 1055 int line, struct lock_object *interlock) 1056 { 1057 struct lock_list_entry *lock_list, *lle; 1058 struct lock_instance *lock1, *lock2, *plock; 1059 struct lock_class *class, *iclass; 1060 struct witness *w, *w1; 1061 struct thread *td; 1062 int i, j; 1063 1064 if (witness_cold || witness_watch < 1 || lock->lo_witness == NULL || 1065 panicstr != NULL) 1066 return; 1067 1068 w = lock->lo_witness; 1069 class = LOCK_CLASS(lock); 1070 td = curthread; 1071 1072 if (class->lc_flags & LC_SLEEPLOCK) { 1073 1074 /* 1075 * Since spin locks include a critical section, this check 1076 * implicitly enforces a lock order of all sleep locks before 1077 * all spin locks. 1078 */ 1079 if (td->td_critnest != 0 && !kdb_active) 1080 kassert_panic("acquiring blockable sleep lock with " 1081 "spinlock or critical section held (%s) %s @ %s:%d", 1082 class->lc_name, lock->lo_name, 1083 fixup_filename(file), line); 1084 1085 /* 1086 * If this is the first lock acquired then just return as 1087 * no order checking is needed. 1088 */ 1089 lock_list = td->td_sleeplocks; 1090 if (lock_list == NULL || lock_list->ll_count == 0) 1091 return; 1092 } else { 1093 1094 /* 1095 * If this is the first lock, just return as no order 1096 * checking is needed. Avoid problems with thread 1097 * migration pinning the thread while checking if 1098 * spinlocks are held. If at least one spinlock is held 1099 * the thread is in a safe path and it is allowed to 1100 * unpin it. 1101 */ 1102 sched_pin(); 1103 lock_list = PCPU_GET(spinlocks); 1104 if (lock_list == NULL || lock_list->ll_count == 0) { 1105 sched_unpin(); 1106 return; 1107 } 1108 sched_unpin(); 1109 } 1110 1111 /* 1112 * Check to see if we are recursing on a lock we already own. If 1113 * so, make sure that we don't mismatch exclusive and shared lock 1114 * acquires. 1115 */ 1116 lock1 = find_instance(lock_list, lock); 1117 if (lock1 != NULL) { 1118 if ((lock1->li_flags & LI_EXCLUSIVE) != 0 && 1119 (flags & LOP_EXCLUSIVE) == 0) { 1120 printf("shared lock of (%s) %s @ %s:%d\n", 1121 class->lc_name, lock->lo_name, 1122 fixup_filename(file), line); 1123 printf("while exclusively locked from %s:%d\n", 1124 fixup_filename(lock1->li_file), lock1->li_line); 1125 kassert_panic("excl->share"); 1126 } 1127 if ((lock1->li_flags & LI_EXCLUSIVE) == 0 && 1128 (flags & LOP_EXCLUSIVE) != 0) { 1129 printf("exclusive lock of (%s) %s @ %s:%d\n", 1130 class->lc_name, lock->lo_name, 1131 fixup_filename(file), line); 1132 printf("while share locked from %s:%d\n", 1133 fixup_filename(lock1->li_file), lock1->li_line); 1134 kassert_panic("share->excl"); 1135 } 1136 return; 1137 } 1138 1139 /* Warn if the interlock is not locked exactly once. */ 1140 if (interlock != NULL) { 1141 iclass = LOCK_CLASS(interlock); 1142 lock1 = find_instance(lock_list, interlock); 1143 if (lock1 == NULL) 1144 kassert_panic("interlock (%s) %s not locked @ %s:%d", 1145 iclass->lc_name, interlock->lo_name, 1146 fixup_filename(file), line); 1147 else if ((lock1->li_flags & LI_RECURSEMASK) != 0) 1148 kassert_panic("interlock (%s) %s recursed @ %s:%d", 1149 iclass->lc_name, interlock->lo_name, 1150 fixup_filename(file), line); 1151 } 1152 1153 /* 1154 * Find the previously acquired lock, but ignore interlocks. 1155 */ 1156 plock = &lock_list->ll_children[lock_list->ll_count - 1]; 1157 if (interlock != NULL && plock->li_lock == interlock) { 1158 if (lock_list->ll_count > 1) 1159 plock = 1160 &lock_list->ll_children[lock_list->ll_count - 2]; 1161 else { 1162 lle = lock_list->ll_next; 1163 1164 /* 1165 * The interlock is the only lock we hold, so 1166 * simply return. 1167 */ 1168 if (lle == NULL) 1169 return; 1170 plock = &lle->ll_children[lle->ll_count - 1]; 1171 } 1172 } 1173 1174 /* 1175 * Try to perform most checks without a lock. If this succeeds we 1176 * can skip acquiring the lock and return success. Otherwise we redo 1177 * the check with the lock held to handle races with concurrent updates. 1178 */ 1179 w1 = plock->li_lock->lo_witness; 1180 if (witness_lock_order_check(w1, w)) 1181 return; 1182 1183 mtx_lock_spin(&w_mtx); 1184 if (witness_lock_order_check(w1, w)) { 1185 mtx_unlock_spin(&w_mtx); 1186 return; 1187 } 1188 witness_lock_order_add(w1, w); 1189 1190 /* 1191 * Check for duplicate locks of the same type. Note that we only 1192 * have to check for this on the last lock we just acquired. Any 1193 * other cases will be caught as lock order violations. 1194 */ 1195 if (w1 == w) { 1196 i = w->w_index; 1197 if (!(lock->lo_flags & LO_DUPOK) && !(flags & LOP_DUPOK) && 1198 !(w_rmatrix[i][i] & WITNESS_REVERSAL)) { 1199 w_rmatrix[i][i] |= WITNESS_REVERSAL; 1200 w->w_reversed = 1; 1201 mtx_unlock_spin(&w_mtx); 1202 printf( 1203 "acquiring duplicate lock of same type: \"%s\"\n", 1204 w->w_name); 1205 printf(" 1st %s @ %s:%d\n", plock->li_lock->lo_name, 1206 fixup_filename(plock->li_file), plock->li_line); 1207 printf(" 2nd %s @ %s:%d\n", lock->lo_name, 1208 fixup_filename(file), line); 1209 witness_debugger(1); 1210 } else 1211 mtx_unlock_spin(&w_mtx); 1212 return; 1213 } 1214 mtx_assert(&w_mtx, MA_OWNED); 1215 1216 /* 1217 * If we know that the lock we are acquiring comes after 1218 * the lock we most recently acquired in the lock order tree, 1219 * then there is no need for any further checks. 1220 */ 1221 if (isitmychild(w1, w)) 1222 goto out; 1223 1224 for (j = 0, lle = lock_list; lle != NULL; lle = lle->ll_next) { 1225 for (i = lle->ll_count - 1; i >= 0; i--, j++) { 1226 1227 MPASS(j < LOCK_CHILDCOUNT * LOCK_NCHILDREN); 1228 lock1 = &lle->ll_children[i]; 1229 1230 /* 1231 * Ignore the interlock. 1232 */ 1233 if (interlock == lock1->li_lock) 1234 continue; 1235 1236 /* 1237 * If this lock doesn't undergo witness checking, 1238 * then skip it. 1239 */ 1240 w1 = lock1->li_lock->lo_witness; 1241 if (w1 == NULL) { 1242 KASSERT((lock1->li_lock->lo_flags & LO_WITNESS) == 0, 1243 ("lock missing witness structure")); 1244 continue; 1245 } 1246 1247 /* 1248 * If we are locking Giant and this is a sleepable 1249 * lock, then skip it. 1250 */ 1251 if ((lock1->li_lock->lo_flags & LO_SLEEPABLE) != 0 && 1252 lock == &Giant.lock_object) 1253 continue; 1254 1255 /* 1256 * If we are locking a sleepable lock and this lock 1257 * is Giant, then skip it. 1258 */ 1259 if ((lock->lo_flags & LO_SLEEPABLE) != 0 && 1260 lock1->li_lock == &Giant.lock_object) 1261 continue; 1262 1263 /* 1264 * If we are locking a sleepable lock and this lock 1265 * isn't sleepable, we want to treat it as a lock 1266 * order violation to enfore a general lock order of 1267 * sleepable locks before non-sleepable locks. 1268 */ 1269 if (((lock->lo_flags & LO_SLEEPABLE) != 0 && 1270 (lock1->li_lock->lo_flags & LO_SLEEPABLE) == 0)) 1271 goto reversal; 1272 1273 /* 1274 * If we are locking Giant and this is a non-sleepable 1275 * lock, then treat it as a reversal. 1276 */ 1277 if ((lock1->li_lock->lo_flags & LO_SLEEPABLE) == 0 && 1278 lock == &Giant.lock_object) 1279 goto reversal; 1280 1281 /* 1282 * Check the lock order hierarchy for a reveresal. 1283 */ 1284 if (!isitmydescendant(w, w1)) 1285 continue; 1286 reversal: 1287 1288 /* 1289 * We have a lock order violation, check to see if it 1290 * is allowed or has already been yelled about. 1291 */ 1292 #ifdef BLESSING 1293 1294 /* 1295 * If the lock order is blessed, just bail. We don't 1296 * look for other lock order violations though, which 1297 * may be a bug. 1298 */ 1299 if (blessed(w, w1)) 1300 goto out; 1301 #endif 1302 1303 /* Bail if this violation is known */ 1304 if (w_rmatrix[w1->w_index][w->w_index] & WITNESS_REVERSAL) 1305 goto out; 1306 1307 /* Record this as a violation */ 1308 w_rmatrix[w1->w_index][w->w_index] |= WITNESS_REVERSAL; 1309 w_rmatrix[w->w_index][w1->w_index] |= WITNESS_REVERSAL; 1310 w->w_reversed = w1->w_reversed = 1; 1311 witness_increment_graph_generation(); 1312 mtx_unlock_spin(&w_mtx); 1313 1314 #ifdef WITNESS_NO_VNODE 1315 /* 1316 * There are known LORs between VNODE locks. They are 1317 * not an indication of a bug. VNODE locks are flagged 1318 * as such (LO_IS_VNODE) and we don't yell if the LOR 1319 * is between 2 VNODE locks. 1320 */ 1321 if ((lock->lo_flags & LO_IS_VNODE) != 0 && 1322 (lock1->li_lock->lo_flags & LO_IS_VNODE) != 0) 1323 return; 1324 #endif 1325 1326 /* 1327 * Ok, yell about it. 1328 */ 1329 if (((lock->lo_flags & LO_SLEEPABLE) != 0 && 1330 (lock1->li_lock->lo_flags & LO_SLEEPABLE) == 0)) 1331 printf( 1332 "lock order reversal: (sleepable after non-sleepable)\n"); 1333 else if ((lock1->li_lock->lo_flags & LO_SLEEPABLE) == 0 1334 && lock == &Giant.lock_object) 1335 printf( 1336 "lock order reversal: (Giant after non-sleepable)\n"); 1337 else 1338 printf("lock order reversal:\n"); 1339 1340 /* 1341 * Try to locate an earlier lock with 1342 * witness w in our list. 1343 */ 1344 do { 1345 lock2 = &lle->ll_children[i]; 1346 MPASS(lock2->li_lock != NULL); 1347 if (lock2->li_lock->lo_witness == w) 1348 break; 1349 if (i == 0 && lle->ll_next != NULL) { 1350 lle = lle->ll_next; 1351 i = lle->ll_count - 1; 1352 MPASS(i >= 0 && i < LOCK_NCHILDREN); 1353 } else 1354 i--; 1355 } while (i >= 0); 1356 if (i < 0) { 1357 printf(" 1st %p %s (%s) @ %s:%d\n", 1358 lock1->li_lock, lock1->li_lock->lo_name, 1359 w1->w_name, fixup_filename(lock1->li_file), 1360 lock1->li_line); 1361 printf(" 2nd %p %s (%s) @ %s:%d\n", lock, 1362 lock->lo_name, w->w_name, 1363 fixup_filename(file), line); 1364 } else { 1365 printf(" 1st %p %s (%s) @ %s:%d\n", 1366 lock2->li_lock, lock2->li_lock->lo_name, 1367 lock2->li_lock->lo_witness->w_name, 1368 fixup_filename(lock2->li_file), 1369 lock2->li_line); 1370 printf(" 2nd %p %s (%s) @ %s:%d\n", 1371 lock1->li_lock, lock1->li_lock->lo_name, 1372 w1->w_name, fixup_filename(lock1->li_file), 1373 lock1->li_line); 1374 printf(" 3rd %p %s (%s) @ %s:%d\n", lock, 1375 lock->lo_name, w->w_name, 1376 fixup_filename(file), line); 1377 } 1378 witness_debugger(1); 1379 return; 1380 } 1381 } 1382 1383 /* 1384 * If requested, build a new lock order. However, don't build a new 1385 * relationship between a sleepable lock and Giant if it is in the 1386 * wrong direction. The correct lock order is that sleepable locks 1387 * always come before Giant. 1388 */ 1389 if (flags & LOP_NEWORDER && 1390 !(plock->li_lock == &Giant.lock_object && 1391 (lock->lo_flags & LO_SLEEPABLE) != 0)) { 1392 CTR3(KTR_WITNESS, "%s: adding %s as a child of %s", __func__, 1393 w->w_name, plock->li_lock->lo_witness->w_name); 1394 itismychild(plock->li_lock->lo_witness, w); 1395 } 1396 out: 1397 mtx_unlock_spin(&w_mtx); 1398 } 1399 1400 void 1401 witness_lock(struct lock_object *lock, int flags, const char *file, int line) 1402 { 1403 struct lock_list_entry **lock_list, *lle; 1404 struct lock_instance *instance; 1405 struct witness *w; 1406 struct thread *td; 1407 1408 if (witness_cold || witness_watch == -1 || lock->lo_witness == NULL || 1409 panicstr != NULL) 1410 return; 1411 w = lock->lo_witness; 1412 td = curthread; 1413 1414 /* Determine lock list for this lock. */ 1415 if (LOCK_CLASS(lock)->lc_flags & LC_SLEEPLOCK) 1416 lock_list = &td->td_sleeplocks; 1417 else 1418 lock_list = PCPU_PTR(spinlocks); 1419 1420 /* Check to see if we are recursing on a lock we already own. */ 1421 instance = find_instance(*lock_list, lock); 1422 if (instance != NULL) { 1423 instance->li_flags++; 1424 CTR4(KTR_WITNESS, "%s: pid %d recursed on %s r=%d", __func__, 1425 td->td_proc->p_pid, lock->lo_name, 1426 instance->li_flags & LI_RECURSEMASK); 1427 instance->li_file = file; 1428 instance->li_line = line; 1429 return; 1430 } 1431 1432 /* Update per-witness last file and line acquire. */ 1433 w->w_file = file; 1434 w->w_line = line; 1435 1436 /* Find the next open lock instance in the list and fill it. */ 1437 lle = *lock_list; 1438 if (lle == NULL || lle->ll_count == LOCK_NCHILDREN) { 1439 lle = witness_lock_list_get(); 1440 if (lle == NULL) 1441 return; 1442 lle->ll_next = *lock_list; 1443 CTR3(KTR_WITNESS, "%s: pid %d added lle %p", __func__, 1444 td->td_proc->p_pid, lle); 1445 *lock_list = lle; 1446 } 1447 instance = &lle->ll_children[lle->ll_count++]; 1448 instance->li_lock = lock; 1449 instance->li_line = line; 1450 instance->li_file = file; 1451 if ((flags & LOP_EXCLUSIVE) != 0) 1452 instance->li_flags = LI_EXCLUSIVE; 1453 else 1454 instance->li_flags = 0; 1455 CTR4(KTR_WITNESS, "%s: pid %d added %s as lle[%d]", __func__, 1456 td->td_proc->p_pid, lock->lo_name, lle->ll_count - 1); 1457 } 1458 1459 void 1460 witness_upgrade(struct lock_object *lock, int flags, const char *file, int line) 1461 { 1462 struct lock_instance *instance; 1463 struct lock_class *class; 1464 1465 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); 1466 if (lock->lo_witness == NULL || witness_watch == -1 || panicstr != NULL) 1467 return; 1468 class = LOCK_CLASS(lock); 1469 if (witness_watch) { 1470 if ((lock->lo_flags & LO_UPGRADABLE) == 0) 1471 kassert_panic( 1472 "upgrade of non-upgradable lock (%s) %s @ %s:%d", 1473 class->lc_name, lock->lo_name, 1474 fixup_filename(file), line); 1475 if ((class->lc_flags & LC_SLEEPLOCK) == 0) 1476 kassert_panic( 1477 "upgrade of non-sleep lock (%s) %s @ %s:%d", 1478 class->lc_name, lock->lo_name, 1479 fixup_filename(file), line); 1480 } 1481 instance = find_instance(curthread->td_sleeplocks, lock); 1482 if (instance == NULL) { 1483 kassert_panic("upgrade of unlocked lock (%s) %s @ %s:%d", 1484 class->lc_name, lock->lo_name, 1485 fixup_filename(file), line); 1486 return; 1487 } 1488 if (witness_watch) { 1489 if ((instance->li_flags & LI_EXCLUSIVE) != 0) 1490 kassert_panic( 1491 "upgrade of exclusive lock (%s) %s @ %s:%d", 1492 class->lc_name, lock->lo_name, 1493 fixup_filename(file), line); 1494 if ((instance->li_flags & LI_RECURSEMASK) != 0) 1495 kassert_panic( 1496 "upgrade of recursed lock (%s) %s r=%d @ %s:%d", 1497 class->lc_name, lock->lo_name, 1498 instance->li_flags & LI_RECURSEMASK, 1499 fixup_filename(file), line); 1500 } 1501 instance->li_flags |= LI_EXCLUSIVE; 1502 } 1503 1504 void 1505 witness_downgrade(struct lock_object *lock, int flags, const char *file, 1506 int line) 1507 { 1508 struct lock_instance *instance; 1509 struct lock_class *class; 1510 1511 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); 1512 if (lock->lo_witness == NULL || witness_watch == -1 || panicstr != NULL) 1513 return; 1514 class = LOCK_CLASS(lock); 1515 if (witness_watch) { 1516 if ((lock->lo_flags & LO_UPGRADABLE) == 0) 1517 kassert_panic( 1518 "downgrade of non-upgradable lock (%s) %s @ %s:%d", 1519 class->lc_name, lock->lo_name, 1520 fixup_filename(file), line); 1521 if ((class->lc_flags & LC_SLEEPLOCK) == 0) 1522 kassert_panic( 1523 "downgrade of non-sleep lock (%s) %s @ %s:%d", 1524 class->lc_name, lock->lo_name, 1525 fixup_filename(file), line); 1526 } 1527 instance = find_instance(curthread->td_sleeplocks, lock); 1528 if (instance == NULL) { 1529 kassert_panic("downgrade of unlocked lock (%s) %s @ %s:%d", 1530 class->lc_name, lock->lo_name, 1531 fixup_filename(file), line); 1532 return; 1533 } 1534 if (witness_watch) { 1535 if ((instance->li_flags & LI_EXCLUSIVE) == 0) 1536 kassert_panic( 1537 "downgrade of shared lock (%s) %s @ %s:%d", 1538 class->lc_name, lock->lo_name, 1539 fixup_filename(file), line); 1540 if ((instance->li_flags & LI_RECURSEMASK) != 0) 1541 kassert_panic( 1542 "downgrade of recursed lock (%s) %s r=%d @ %s:%d", 1543 class->lc_name, lock->lo_name, 1544 instance->li_flags & LI_RECURSEMASK, 1545 fixup_filename(file), line); 1546 } 1547 instance->li_flags &= ~LI_EXCLUSIVE; 1548 } 1549 1550 void 1551 witness_unlock(struct lock_object *lock, int flags, const char *file, int line) 1552 { 1553 struct lock_list_entry **lock_list, *lle; 1554 struct lock_instance *instance; 1555 struct lock_class *class; 1556 struct thread *td; 1557 register_t s; 1558 int i, j; 1559 1560 if (witness_cold || lock->lo_witness == NULL || panicstr != NULL) 1561 return; 1562 td = curthread; 1563 class = LOCK_CLASS(lock); 1564 1565 /* Find lock instance associated with this lock. */ 1566 if (class->lc_flags & LC_SLEEPLOCK) 1567 lock_list = &td->td_sleeplocks; 1568 else 1569 lock_list = PCPU_PTR(spinlocks); 1570 lle = *lock_list; 1571 for (; *lock_list != NULL; lock_list = &(*lock_list)->ll_next) 1572 for (i = 0; i < (*lock_list)->ll_count; i++) { 1573 instance = &(*lock_list)->ll_children[i]; 1574 if (instance->li_lock == lock) 1575 goto found; 1576 } 1577 1578 /* 1579 * When disabling WITNESS through witness_watch we could end up in 1580 * having registered locks in the td_sleeplocks queue. 1581 * We have to make sure we flush these queues, so just search for 1582 * eventual register locks and remove them. 1583 */ 1584 if (witness_watch > 0) { 1585 kassert_panic("lock (%s) %s not locked @ %s:%d", class->lc_name, 1586 lock->lo_name, fixup_filename(file), line); 1587 return; 1588 } else { 1589 return; 1590 } 1591 found: 1592 1593 /* First, check for shared/exclusive mismatches. */ 1594 if ((instance->li_flags & LI_EXCLUSIVE) != 0 && witness_watch > 0 && 1595 (flags & LOP_EXCLUSIVE) == 0) { 1596 printf("shared unlock of (%s) %s @ %s:%d\n", class->lc_name, 1597 lock->lo_name, fixup_filename(file), line); 1598 printf("while exclusively locked from %s:%d\n", 1599 fixup_filename(instance->li_file), instance->li_line); 1600 kassert_panic("excl->ushare"); 1601 } 1602 if ((instance->li_flags & LI_EXCLUSIVE) == 0 && witness_watch > 0 && 1603 (flags & LOP_EXCLUSIVE) != 0) { 1604 printf("exclusive unlock of (%s) %s @ %s:%d\n", class->lc_name, 1605 lock->lo_name, fixup_filename(file), line); 1606 printf("while share locked from %s:%d\n", 1607 fixup_filename(instance->li_file), 1608 instance->li_line); 1609 kassert_panic("share->uexcl"); 1610 } 1611 /* If we are recursed, unrecurse. */ 1612 if ((instance->li_flags & LI_RECURSEMASK) > 0) { 1613 CTR4(KTR_WITNESS, "%s: pid %d unrecursed on %s r=%d", __func__, 1614 td->td_proc->p_pid, instance->li_lock->lo_name, 1615 instance->li_flags); 1616 instance->li_flags--; 1617 return; 1618 } 1619 /* The lock is now being dropped, check for NORELEASE flag */ 1620 if ((instance->li_flags & LI_NORELEASE) != 0 && witness_watch > 0) { 1621 printf("forbidden unlock of (%s) %s @ %s:%d\n", class->lc_name, 1622 lock->lo_name, fixup_filename(file), line); 1623 kassert_panic("lock marked norelease"); 1624 } 1625 1626 /* Otherwise, remove this item from the list. */ 1627 s = intr_disable(); 1628 CTR4(KTR_WITNESS, "%s: pid %d removed %s from lle[%d]", __func__, 1629 td->td_proc->p_pid, instance->li_lock->lo_name, 1630 (*lock_list)->ll_count - 1); 1631 for (j = i; j < (*lock_list)->ll_count - 1; j++) 1632 (*lock_list)->ll_children[j] = 1633 (*lock_list)->ll_children[j + 1]; 1634 (*lock_list)->ll_count--; 1635 intr_restore(s); 1636 1637 /* 1638 * In order to reduce contention on w_mtx, we want to keep always an 1639 * head object into lists so that frequent allocation from the 1640 * free witness pool (and subsequent locking) is avoided. 1641 * In order to maintain the current code simple, when the head 1642 * object is totally unloaded it means also that we do not have 1643 * further objects in the list, so the list ownership needs to be 1644 * hand over to another object if the current head needs to be freed. 1645 */ 1646 if ((*lock_list)->ll_count == 0) { 1647 if (*lock_list == lle) { 1648 if (lle->ll_next == NULL) 1649 return; 1650 } else 1651 lle = *lock_list; 1652 *lock_list = lle->ll_next; 1653 CTR3(KTR_WITNESS, "%s: pid %d removed lle %p", __func__, 1654 td->td_proc->p_pid, lle); 1655 witness_lock_list_free(lle); 1656 } 1657 } 1658 1659 void 1660 witness_thread_exit(struct thread *td) 1661 { 1662 struct lock_list_entry *lle; 1663 int i, n; 1664 1665 lle = td->td_sleeplocks; 1666 if (lle == NULL || panicstr != NULL) 1667 return; 1668 if (lle->ll_count != 0) { 1669 for (n = 0; lle != NULL; lle = lle->ll_next) 1670 for (i = lle->ll_count - 1; i >= 0; i--) { 1671 if (n == 0) 1672 printf("Thread %p exiting with the following locks held:\n", 1673 td); 1674 n++; 1675 witness_list_lock(&lle->ll_children[i], printf); 1676 1677 } 1678 kassert_panic( 1679 "Thread %p cannot exit while holding sleeplocks\n", td); 1680 } 1681 witness_lock_list_free(lle); 1682 } 1683 1684 /* 1685 * Warn if any locks other than 'lock' are held. Flags can be passed in to 1686 * exempt Giant and sleepable locks from the checks as well. If any 1687 * non-exempt locks are held, then a supplied message is printed to the 1688 * console along with a list of the offending locks. If indicated in the 1689 * flags then a failure results in a panic as well. 1690 */ 1691 int 1692 witness_warn(int flags, struct lock_object *lock, const char *fmt, ...) 1693 { 1694 struct lock_list_entry *lock_list, *lle; 1695 struct lock_instance *lock1; 1696 struct thread *td; 1697 va_list ap; 1698 int i, n; 1699 1700 if (witness_cold || witness_watch < 1 || panicstr != NULL) 1701 return (0); 1702 n = 0; 1703 td = curthread; 1704 for (lle = td->td_sleeplocks; lle != NULL; lle = lle->ll_next) 1705 for (i = lle->ll_count - 1; i >= 0; i--) { 1706 lock1 = &lle->ll_children[i]; 1707 if (lock1->li_lock == lock) 1708 continue; 1709 if (flags & WARN_GIANTOK && 1710 lock1->li_lock == &Giant.lock_object) 1711 continue; 1712 if (flags & WARN_SLEEPOK && 1713 (lock1->li_lock->lo_flags & LO_SLEEPABLE) != 0) 1714 continue; 1715 if (n == 0) { 1716 va_start(ap, fmt); 1717 vprintf(fmt, ap); 1718 va_end(ap); 1719 printf(" with the following"); 1720 if (flags & WARN_SLEEPOK) 1721 printf(" non-sleepable"); 1722 printf(" locks held:\n"); 1723 } 1724 n++; 1725 witness_list_lock(lock1, printf); 1726 } 1727 1728 /* 1729 * Pin the thread in order to avoid problems with thread migration. 1730 * Once that all verifies are passed about spinlocks ownership, 1731 * the thread is in a safe path and it can be unpinned. 1732 */ 1733 sched_pin(); 1734 lock_list = PCPU_GET(spinlocks); 1735 if (lock_list != NULL && lock_list->ll_count != 0) { 1736 sched_unpin(); 1737 1738 /* 1739 * We should only have one spinlock and as long as 1740 * the flags cannot match for this locks class, 1741 * check if the first spinlock is the one curthread 1742 * should hold. 1743 */ 1744 lock1 = &lock_list->ll_children[lock_list->ll_count - 1]; 1745 if (lock_list->ll_count == 1 && lock_list->ll_next == NULL && 1746 lock1->li_lock == lock && n == 0) 1747 return (0); 1748 1749 va_start(ap, fmt); 1750 vprintf(fmt, ap); 1751 va_end(ap); 1752 printf(" with the following"); 1753 if (flags & WARN_SLEEPOK) 1754 printf(" non-sleepable"); 1755 printf(" locks held:\n"); 1756 n += witness_list_locks(&lock_list, printf); 1757 } else 1758 sched_unpin(); 1759 if (flags & WARN_PANIC && n) 1760 kassert_panic("%s", __func__); 1761 else 1762 witness_debugger(n); 1763 return (n); 1764 } 1765 1766 const char * 1767 witness_file(struct lock_object *lock) 1768 { 1769 struct witness *w; 1770 1771 if (witness_cold || witness_watch < 1 || lock->lo_witness == NULL) 1772 return ("?"); 1773 w = lock->lo_witness; 1774 return (w->w_file); 1775 } 1776 1777 int 1778 witness_line(struct lock_object *lock) 1779 { 1780 struct witness *w; 1781 1782 if (witness_cold || witness_watch < 1 || lock->lo_witness == NULL) 1783 return (0); 1784 w = lock->lo_witness; 1785 return (w->w_line); 1786 } 1787 1788 static struct witness * 1789 enroll(const char *description, struct lock_class *lock_class) 1790 { 1791 struct witness *w; 1792 struct witness_list *typelist; 1793 1794 MPASS(description != NULL); 1795 1796 if (witness_watch == -1 || panicstr != NULL) 1797 return (NULL); 1798 if ((lock_class->lc_flags & LC_SPINLOCK)) { 1799 if (witness_skipspin) 1800 return (NULL); 1801 else 1802 typelist = &w_spin; 1803 } else if ((lock_class->lc_flags & LC_SLEEPLOCK)) { 1804 typelist = &w_sleep; 1805 } else { 1806 kassert_panic("lock class %s is not sleep or spin", 1807 lock_class->lc_name); 1808 return (NULL); 1809 } 1810 1811 mtx_lock_spin(&w_mtx); 1812 w = witness_hash_get(description); 1813 if (w) 1814 goto found; 1815 if ((w = witness_get()) == NULL) 1816 return (NULL); 1817 MPASS(strlen(description) < MAX_W_NAME); 1818 strcpy(w->w_name, description); 1819 w->w_class = lock_class; 1820 w->w_refcount = 1; 1821 STAILQ_INSERT_HEAD(&w_all, w, w_list); 1822 if (lock_class->lc_flags & LC_SPINLOCK) { 1823 STAILQ_INSERT_HEAD(&w_spin, w, w_typelist); 1824 w_spin_cnt++; 1825 } else if (lock_class->lc_flags & LC_SLEEPLOCK) { 1826 STAILQ_INSERT_HEAD(&w_sleep, w, w_typelist); 1827 w_sleep_cnt++; 1828 } 1829 1830 /* Insert new witness into the hash */ 1831 witness_hash_put(w); 1832 witness_increment_graph_generation(); 1833 mtx_unlock_spin(&w_mtx); 1834 return (w); 1835 found: 1836 w->w_refcount++; 1837 mtx_unlock_spin(&w_mtx); 1838 if (lock_class != w->w_class) 1839 kassert_panic( 1840 "lock (%s) %s does not match earlier (%s) lock", 1841 description, lock_class->lc_name, 1842 w->w_class->lc_name); 1843 return (w); 1844 } 1845 1846 static void 1847 depart(struct witness *w) 1848 { 1849 struct witness_list *list; 1850 1851 MPASS(w->w_refcount == 0); 1852 if (w->w_class->lc_flags & LC_SLEEPLOCK) { 1853 list = &w_sleep; 1854 w_sleep_cnt--; 1855 } else { 1856 list = &w_spin; 1857 w_spin_cnt--; 1858 } 1859 /* 1860 * Set file to NULL as it may point into a loadable module. 1861 */ 1862 w->w_file = NULL; 1863 w->w_line = 0; 1864 witness_increment_graph_generation(); 1865 } 1866 1867 1868 static void 1869 adopt(struct witness *parent, struct witness *child) 1870 { 1871 int pi, ci, i, j; 1872 1873 if (witness_cold == 0) 1874 mtx_assert(&w_mtx, MA_OWNED); 1875 1876 /* If the relationship is already known, there's no work to be done. */ 1877 if (isitmychild(parent, child)) 1878 return; 1879 1880 /* When the structure of the graph changes, bump up the generation. */ 1881 witness_increment_graph_generation(); 1882 1883 /* 1884 * The hard part ... create the direct relationship, then propagate all 1885 * indirect relationships. 1886 */ 1887 pi = parent->w_index; 1888 ci = child->w_index; 1889 WITNESS_INDEX_ASSERT(pi); 1890 WITNESS_INDEX_ASSERT(ci); 1891 MPASS(pi != ci); 1892 w_rmatrix[pi][ci] |= WITNESS_PARENT; 1893 w_rmatrix[ci][pi] |= WITNESS_CHILD; 1894 1895 /* 1896 * If parent was not already an ancestor of child, 1897 * then we increment the descendant and ancestor counters. 1898 */ 1899 if ((w_rmatrix[pi][ci] & WITNESS_ANCESTOR) == 0) { 1900 parent->w_num_descendants++; 1901 child->w_num_ancestors++; 1902 } 1903 1904 /* 1905 * Find each ancestor of 'pi'. Note that 'pi' itself is counted as 1906 * an ancestor of 'pi' during this loop. 1907 */ 1908 for (i = 1; i <= w_max_used_index; i++) { 1909 if ((w_rmatrix[i][pi] & WITNESS_ANCESTOR_MASK) == 0 && 1910 (i != pi)) 1911 continue; 1912 1913 /* Find each descendant of 'i' and mark it as a descendant. */ 1914 for (j = 1; j <= w_max_used_index; j++) { 1915 1916 /* 1917 * Skip children that are already marked as 1918 * descendants of 'i'. 1919 */ 1920 if (w_rmatrix[i][j] & WITNESS_ANCESTOR_MASK) 1921 continue; 1922 1923 /* 1924 * We are only interested in descendants of 'ci'. Note 1925 * that 'ci' itself is counted as a descendant of 'ci'. 1926 */ 1927 if ((w_rmatrix[ci][j] & WITNESS_ANCESTOR_MASK) == 0 && 1928 (j != ci)) 1929 continue; 1930 w_rmatrix[i][j] |= WITNESS_ANCESTOR; 1931 w_rmatrix[j][i] |= WITNESS_DESCENDANT; 1932 w_data[i].w_num_descendants++; 1933 w_data[j].w_num_ancestors++; 1934 1935 /* 1936 * Make sure we aren't marking a node as both an 1937 * ancestor and descendant. We should have caught 1938 * this as a lock order reversal earlier. 1939 */ 1940 if ((w_rmatrix[i][j] & WITNESS_ANCESTOR_MASK) && 1941 (w_rmatrix[i][j] & WITNESS_DESCENDANT_MASK)) { 1942 printf("witness rmatrix paradox! [%d][%d]=%d " 1943 "both ancestor and descendant\n", 1944 i, j, w_rmatrix[i][j]); 1945 kdb_backtrace(); 1946 printf("Witness disabled.\n"); 1947 witness_watch = -1; 1948 } 1949 if ((w_rmatrix[j][i] & WITNESS_ANCESTOR_MASK) && 1950 (w_rmatrix[j][i] & WITNESS_DESCENDANT_MASK)) { 1951 printf("witness rmatrix paradox! [%d][%d]=%d " 1952 "both ancestor and descendant\n", 1953 j, i, w_rmatrix[j][i]); 1954 kdb_backtrace(); 1955 printf("Witness disabled.\n"); 1956 witness_watch = -1; 1957 } 1958 } 1959 } 1960 } 1961 1962 static void 1963 itismychild(struct witness *parent, struct witness *child) 1964 { 1965 int unlocked; 1966 1967 MPASS(child != NULL && parent != NULL); 1968 if (witness_cold == 0) 1969 mtx_assert(&w_mtx, MA_OWNED); 1970 1971 if (!witness_lock_type_equal(parent, child)) { 1972 if (witness_cold == 0) { 1973 unlocked = 1; 1974 mtx_unlock_spin(&w_mtx); 1975 } else { 1976 unlocked = 0; 1977 } 1978 kassert_panic( 1979 "%s: parent \"%s\" (%s) and child \"%s\" (%s) are not " 1980 "the same lock type", __func__, parent->w_name, 1981 parent->w_class->lc_name, child->w_name, 1982 child->w_class->lc_name); 1983 if (unlocked) 1984 mtx_lock_spin(&w_mtx); 1985 } 1986 adopt(parent, child); 1987 } 1988 1989 /* 1990 * Generic code for the isitmy*() functions. The rmask parameter is the 1991 * expected relationship of w1 to w2. 1992 */ 1993 static int 1994 _isitmyx(struct witness *w1, struct witness *w2, int rmask, const char *fname) 1995 { 1996 unsigned char r1, r2; 1997 int i1, i2; 1998 1999 i1 = w1->w_index; 2000 i2 = w2->w_index; 2001 WITNESS_INDEX_ASSERT(i1); 2002 WITNESS_INDEX_ASSERT(i2); 2003 r1 = w_rmatrix[i1][i2] & WITNESS_RELATED_MASK; 2004 r2 = w_rmatrix[i2][i1] & WITNESS_RELATED_MASK; 2005 2006 /* The flags on one better be the inverse of the flags on the other */ 2007 if (!((WITNESS_ATOD(r1) == r2 && WITNESS_DTOA(r2) == r1) || 2008 (WITNESS_DTOA(r1) == r2 && WITNESS_ATOD(r2) == r1))) { 2009 /* Don't squawk if we're potentially racing with an update. */ 2010 if (!mtx_owned(&w_mtx)) 2011 return (0); 2012 printf("%s: rmatrix mismatch between %s (index %d) and %s " 2013 "(index %d): w_rmatrix[%d][%d] == %hhx but " 2014 "w_rmatrix[%d][%d] == %hhx\n", 2015 fname, w1->w_name, i1, w2->w_name, i2, i1, i2, r1, 2016 i2, i1, r2); 2017 kdb_backtrace(); 2018 printf("Witness disabled.\n"); 2019 witness_watch = -1; 2020 } 2021 return (r1 & rmask); 2022 } 2023 2024 /* 2025 * Checks if @child is a direct child of @parent. 2026 */ 2027 static int 2028 isitmychild(struct witness *parent, struct witness *child) 2029 { 2030 2031 return (_isitmyx(parent, child, WITNESS_PARENT, __func__)); 2032 } 2033 2034 /* 2035 * Checks if @descendant is a direct or inderect descendant of @ancestor. 2036 */ 2037 static int 2038 isitmydescendant(struct witness *ancestor, struct witness *descendant) 2039 { 2040 2041 return (_isitmyx(ancestor, descendant, WITNESS_ANCESTOR_MASK, 2042 __func__)); 2043 } 2044 2045 #ifdef BLESSING 2046 static int 2047 blessed(struct witness *w1, struct witness *w2) 2048 { 2049 int i; 2050 struct witness_blessed *b; 2051 2052 for (i = 0; i < blessed_count; i++) { 2053 b = &blessed_list[i]; 2054 if (strcmp(w1->w_name, b->b_lock1) == 0) { 2055 if (strcmp(w2->w_name, b->b_lock2) == 0) 2056 return (1); 2057 continue; 2058 } 2059 if (strcmp(w1->w_name, b->b_lock2) == 0) 2060 if (strcmp(w2->w_name, b->b_lock1) == 0) 2061 return (1); 2062 } 2063 return (0); 2064 } 2065 #endif 2066 2067 static struct witness * 2068 witness_get(void) 2069 { 2070 struct witness *w; 2071 int index; 2072 2073 if (witness_cold == 0) 2074 mtx_assert(&w_mtx, MA_OWNED); 2075 2076 if (witness_watch == -1) { 2077 mtx_unlock_spin(&w_mtx); 2078 return (NULL); 2079 } 2080 if (STAILQ_EMPTY(&w_free)) { 2081 witness_watch = -1; 2082 mtx_unlock_spin(&w_mtx); 2083 printf("WITNESS: unable to allocate a new witness object\n"); 2084 return (NULL); 2085 } 2086 w = STAILQ_FIRST(&w_free); 2087 STAILQ_REMOVE_HEAD(&w_free, w_list); 2088 w_free_cnt--; 2089 index = w->w_index; 2090 MPASS(index > 0 && index == w_max_used_index+1 && 2091 index < witness_count); 2092 bzero(w, sizeof(*w)); 2093 w->w_index = index; 2094 if (index > w_max_used_index) 2095 w_max_used_index = index; 2096 return (w); 2097 } 2098 2099 static void 2100 witness_free(struct witness *w) 2101 { 2102 2103 STAILQ_INSERT_HEAD(&w_free, w, w_list); 2104 w_free_cnt++; 2105 } 2106 2107 static struct lock_list_entry * 2108 witness_lock_list_get(void) 2109 { 2110 struct lock_list_entry *lle; 2111 2112 if (witness_watch == -1) 2113 return (NULL); 2114 mtx_lock_spin(&w_mtx); 2115 lle = w_lock_list_free; 2116 if (lle == NULL) { 2117 witness_watch = -1; 2118 mtx_unlock_spin(&w_mtx); 2119 printf("%s: witness exhausted\n", __func__); 2120 return (NULL); 2121 } 2122 w_lock_list_free = lle->ll_next; 2123 mtx_unlock_spin(&w_mtx); 2124 bzero(lle, sizeof(*lle)); 2125 return (lle); 2126 } 2127 2128 static void 2129 witness_lock_list_free(struct lock_list_entry *lle) 2130 { 2131 2132 mtx_lock_spin(&w_mtx); 2133 lle->ll_next = w_lock_list_free; 2134 w_lock_list_free = lle; 2135 mtx_unlock_spin(&w_mtx); 2136 } 2137 2138 static struct lock_instance * 2139 find_instance(struct lock_list_entry *list, const struct lock_object *lock) 2140 { 2141 struct lock_list_entry *lle; 2142 struct lock_instance *instance; 2143 int i; 2144 2145 for (lle = list; lle != NULL; lle = lle->ll_next) 2146 for (i = lle->ll_count - 1; i >= 0; i--) { 2147 instance = &lle->ll_children[i]; 2148 if (instance->li_lock == lock) 2149 return (instance); 2150 } 2151 return (NULL); 2152 } 2153 2154 static void 2155 witness_list_lock(struct lock_instance *instance, 2156 int (*prnt)(const char *fmt, ...)) 2157 { 2158 struct lock_object *lock; 2159 2160 lock = instance->li_lock; 2161 prnt("%s %s %s", (instance->li_flags & LI_EXCLUSIVE) != 0 ? 2162 "exclusive" : "shared", LOCK_CLASS(lock)->lc_name, lock->lo_name); 2163 if (lock->lo_witness->w_name != lock->lo_name) 2164 prnt(" (%s)", lock->lo_witness->w_name); 2165 prnt(" r = %d (%p) locked @ %s:%d\n", 2166 instance->li_flags & LI_RECURSEMASK, lock, 2167 fixup_filename(instance->li_file), instance->li_line); 2168 } 2169 2170 #ifdef DDB 2171 static int 2172 witness_thread_has_locks(struct thread *td) 2173 { 2174 2175 if (td->td_sleeplocks == NULL) 2176 return (0); 2177 return (td->td_sleeplocks->ll_count != 0); 2178 } 2179 2180 static int 2181 witness_proc_has_locks(struct proc *p) 2182 { 2183 struct thread *td; 2184 2185 FOREACH_THREAD_IN_PROC(p, td) { 2186 if (witness_thread_has_locks(td)) 2187 return (1); 2188 } 2189 return (0); 2190 } 2191 #endif 2192 2193 int 2194 witness_list_locks(struct lock_list_entry **lock_list, 2195 int (*prnt)(const char *fmt, ...)) 2196 { 2197 struct lock_list_entry *lle; 2198 int i, nheld; 2199 2200 nheld = 0; 2201 for (lle = *lock_list; lle != NULL; lle = lle->ll_next) 2202 for (i = lle->ll_count - 1; i >= 0; i--) { 2203 witness_list_lock(&lle->ll_children[i], prnt); 2204 nheld++; 2205 } 2206 return (nheld); 2207 } 2208 2209 /* 2210 * This is a bit risky at best. We call this function when we have timed 2211 * out acquiring a spin lock, and we assume that the other CPU is stuck 2212 * with this lock held. So, we go groveling around in the other CPU's 2213 * per-cpu data to try to find the lock instance for this spin lock to 2214 * see when it was last acquired. 2215 */ 2216 void 2217 witness_display_spinlock(struct lock_object *lock, struct thread *owner, 2218 int (*prnt)(const char *fmt, ...)) 2219 { 2220 struct lock_instance *instance; 2221 struct pcpu *pc; 2222 2223 if (owner->td_critnest == 0 || owner->td_oncpu == NOCPU) 2224 return; 2225 pc = pcpu_find(owner->td_oncpu); 2226 instance = find_instance(pc->pc_spinlocks, lock); 2227 if (instance != NULL) 2228 witness_list_lock(instance, prnt); 2229 } 2230 2231 void 2232 witness_save(struct lock_object *lock, const char **filep, int *linep) 2233 { 2234 struct lock_list_entry *lock_list; 2235 struct lock_instance *instance; 2236 struct lock_class *class; 2237 2238 /* 2239 * This function is used independently in locking code to deal with 2240 * Giant, SCHEDULER_STOPPED() check can be removed here after Giant 2241 * is gone. 2242 */ 2243 if (SCHEDULER_STOPPED()) 2244 return; 2245 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); 2246 if (lock->lo_witness == NULL || witness_watch == -1 || panicstr != NULL) 2247 return; 2248 class = LOCK_CLASS(lock); 2249 if (class->lc_flags & LC_SLEEPLOCK) 2250 lock_list = curthread->td_sleeplocks; 2251 else { 2252 if (witness_skipspin) 2253 return; 2254 lock_list = PCPU_GET(spinlocks); 2255 } 2256 instance = find_instance(lock_list, lock); 2257 if (instance == NULL) { 2258 kassert_panic("%s: lock (%s) %s not locked", __func__, 2259 class->lc_name, lock->lo_name); 2260 return; 2261 } 2262 *filep = instance->li_file; 2263 *linep = instance->li_line; 2264 } 2265 2266 void 2267 witness_restore(struct lock_object *lock, const char *file, int line) 2268 { 2269 struct lock_list_entry *lock_list; 2270 struct lock_instance *instance; 2271 struct lock_class *class; 2272 2273 /* 2274 * This function is used independently in locking code to deal with 2275 * Giant, SCHEDULER_STOPPED() check can be removed here after Giant 2276 * is gone. 2277 */ 2278 if (SCHEDULER_STOPPED()) 2279 return; 2280 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); 2281 if (lock->lo_witness == NULL || witness_watch == -1 || panicstr != NULL) 2282 return; 2283 class = LOCK_CLASS(lock); 2284 if (class->lc_flags & LC_SLEEPLOCK) 2285 lock_list = curthread->td_sleeplocks; 2286 else { 2287 if (witness_skipspin) 2288 return; 2289 lock_list = PCPU_GET(spinlocks); 2290 } 2291 instance = find_instance(lock_list, lock); 2292 if (instance == NULL) 2293 kassert_panic("%s: lock (%s) %s not locked", __func__, 2294 class->lc_name, lock->lo_name); 2295 lock->lo_witness->w_file = file; 2296 lock->lo_witness->w_line = line; 2297 if (instance == NULL) 2298 return; 2299 instance->li_file = file; 2300 instance->li_line = line; 2301 } 2302 2303 void 2304 witness_assert(const struct lock_object *lock, int flags, const char *file, 2305 int line) 2306 { 2307 #ifdef INVARIANT_SUPPORT 2308 struct lock_instance *instance; 2309 struct lock_class *class; 2310 2311 if (lock->lo_witness == NULL || witness_watch < 1 || panicstr != NULL) 2312 return; 2313 class = LOCK_CLASS(lock); 2314 if ((class->lc_flags & LC_SLEEPLOCK) != 0) 2315 instance = find_instance(curthread->td_sleeplocks, lock); 2316 else if ((class->lc_flags & LC_SPINLOCK) != 0) 2317 instance = find_instance(PCPU_GET(spinlocks), lock); 2318 else { 2319 kassert_panic("Lock (%s) %s is not sleep or spin!", 2320 class->lc_name, lock->lo_name); 2321 return; 2322 } 2323 switch (flags) { 2324 case LA_UNLOCKED: 2325 if (instance != NULL) 2326 kassert_panic("Lock (%s) %s locked @ %s:%d.", 2327 class->lc_name, lock->lo_name, 2328 fixup_filename(file), line); 2329 break; 2330 case LA_LOCKED: 2331 case LA_LOCKED | LA_RECURSED: 2332 case LA_LOCKED | LA_NOTRECURSED: 2333 case LA_SLOCKED: 2334 case LA_SLOCKED | LA_RECURSED: 2335 case LA_SLOCKED | LA_NOTRECURSED: 2336 case LA_XLOCKED: 2337 case LA_XLOCKED | LA_RECURSED: 2338 case LA_XLOCKED | LA_NOTRECURSED: 2339 if (instance == NULL) { 2340 kassert_panic("Lock (%s) %s not locked @ %s:%d.", 2341 class->lc_name, lock->lo_name, 2342 fixup_filename(file), line); 2343 break; 2344 } 2345 if ((flags & LA_XLOCKED) != 0 && 2346 (instance->li_flags & LI_EXCLUSIVE) == 0) 2347 kassert_panic( 2348 "Lock (%s) %s not exclusively locked @ %s:%d.", 2349 class->lc_name, lock->lo_name, 2350 fixup_filename(file), line); 2351 if ((flags & LA_SLOCKED) != 0 && 2352 (instance->li_flags & LI_EXCLUSIVE) != 0) 2353 kassert_panic( 2354 "Lock (%s) %s exclusively locked @ %s:%d.", 2355 class->lc_name, lock->lo_name, 2356 fixup_filename(file), line); 2357 if ((flags & LA_RECURSED) != 0 && 2358 (instance->li_flags & LI_RECURSEMASK) == 0) 2359 kassert_panic("Lock (%s) %s not recursed @ %s:%d.", 2360 class->lc_name, lock->lo_name, 2361 fixup_filename(file), line); 2362 if ((flags & LA_NOTRECURSED) != 0 && 2363 (instance->li_flags & LI_RECURSEMASK) != 0) 2364 kassert_panic("Lock (%s) %s recursed @ %s:%d.", 2365 class->lc_name, lock->lo_name, 2366 fixup_filename(file), line); 2367 break; 2368 default: 2369 kassert_panic("Invalid lock assertion at %s:%d.", 2370 fixup_filename(file), line); 2371 2372 } 2373 #endif /* INVARIANT_SUPPORT */ 2374 } 2375 2376 static void 2377 witness_setflag(struct lock_object *lock, int flag, int set) 2378 { 2379 struct lock_list_entry *lock_list; 2380 struct lock_instance *instance; 2381 struct lock_class *class; 2382 2383 if (lock->lo_witness == NULL || witness_watch == -1 || panicstr != NULL) 2384 return; 2385 class = LOCK_CLASS(lock); 2386 if (class->lc_flags & LC_SLEEPLOCK) 2387 lock_list = curthread->td_sleeplocks; 2388 else { 2389 if (witness_skipspin) 2390 return; 2391 lock_list = PCPU_GET(spinlocks); 2392 } 2393 instance = find_instance(lock_list, lock); 2394 if (instance == NULL) { 2395 kassert_panic("%s: lock (%s) %s not locked", __func__, 2396 class->lc_name, lock->lo_name); 2397 return; 2398 } 2399 2400 if (set) 2401 instance->li_flags |= flag; 2402 else 2403 instance->li_flags &= ~flag; 2404 } 2405 2406 void 2407 witness_norelease(struct lock_object *lock) 2408 { 2409 2410 witness_setflag(lock, LI_NORELEASE, 1); 2411 } 2412 2413 void 2414 witness_releaseok(struct lock_object *lock) 2415 { 2416 2417 witness_setflag(lock, LI_NORELEASE, 0); 2418 } 2419 2420 #ifdef DDB 2421 static void 2422 witness_ddb_list(struct thread *td) 2423 { 2424 2425 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); 2426 KASSERT(kdb_active, ("%s: not in the debugger", __func__)); 2427 2428 if (witness_watch < 1) 2429 return; 2430 2431 witness_list_locks(&td->td_sleeplocks, db_printf); 2432 2433 /* 2434 * We only handle spinlocks if td == curthread. This is somewhat broken 2435 * if td is currently executing on some other CPU and holds spin locks 2436 * as we won't display those locks. If we had a MI way of getting 2437 * the per-cpu data for a given cpu then we could use 2438 * td->td_oncpu to get the list of spinlocks for this thread 2439 * and "fix" this. 2440 * 2441 * That still wouldn't really fix this unless we locked the scheduler 2442 * lock or stopped the other CPU to make sure it wasn't changing the 2443 * list out from under us. It is probably best to just not try to 2444 * handle threads on other CPU's for now. 2445 */ 2446 if (td == curthread && PCPU_GET(spinlocks) != NULL) 2447 witness_list_locks(PCPU_PTR(spinlocks), db_printf); 2448 } 2449 2450 DB_SHOW_COMMAND(locks, db_witness_list) 2451 { 2452 struct thread *td; 2453 2454 if (have_addr) 2455 td = db_lookup_thread(addr, true); 2456 else 2457 td = kdb_thread; 2458 witness_ddb_list(td); 2459 } 2460 2461 DB_SHOW_ALL_COMMAND(locks, db_witness_list_all) 2462 { 2463 struct thread *td; 2464 struct proc *p; 2465 2466 /* 2467 * It would be nice to list only threads and processes that actually 2468 * held sleep locks, but that information is currently not exported 2469 * by WITNESS. 2470 */ 2471 FOREACH_PROC_IN_SYSTEM(p) { 2472 if (!witness_proc_has_locks(p)) 2473 continue; 2474 FOREACH_THREAD_IN_PROC(p, td) { 2475 if (!witness_thread_has_locks(td)) 2476 continue; 2477 db_printf("Process %d (%s) thread %p (%d)\n", p->p_pid, 2478 p->p_comm, td, td->td_tid); 2479 witness_ddb_list(td); 2480 if (db_pager_quit) 2481 return; 2482 } 2483 } 2484 } 2485 DB_SHOW_ALIAS(alllocks, db_witness_list_all) 2486 2487 DB_SHOW_COMMAND(witness, db_witness_display) 2488 { 2489 2490 witness_ddb_display(db_printf); 2491 } 2492 #endif 2493 2494 static int 2495 sysctl_debug_witness_badstacks(SYSCTL_HANDLER_ARGS) 2496 { 2497 struct witness_lock_order_data *data1, *data2, *tmp_data1, *tmp_data2; 2498 struct witness *tmp_w1, *tmp_w2, *w1, *w2; 2499 struct sbuf *sb; 2500 u_int w_rmatrix1, w_rmatrix2; 2501 int error, generation, i, j; 2502 2503 tmp_data1 = NULL; 2504 tmp_data2 = NULL; 2505 tmp_w1 = NULL; 2506 tmp_w2 = NULL; 2507 if (witness_watch < 1) { 2508 error = SYSCTL_OUT(req, w_notrunning, sizeof(w_notrunning)); 2509 return (error); 2510 } 2511 if (witness_cold) { 2512 error = SYSCTL_OUT(req, w_stillcold, sizeof(w_stillcold)); 2513 return (error); 2514 } 2515 error = 0; 2516 sb = sbuf_new(NULL, NULL, badstack_sbuf_size, SBUF_AUTOEXTEND); 2517 if (sb == NULL) 2518 return (ENOMEM); 2519 2520 /* Allocate and init temporary storage space. */ 2521 tmp_w1 = malloc(sizeof(struct witness), M_TEMP, M_WAITOK | M_ZERO); 2522 tmp_w2 = malloc(sizeof(struct witness), M_TEMP, M_WAITOK | M_ZERO); 2523 tmp_data1 = malloc(sizeof(struct witness_lock_order_data), M_TEMP, 2524 M_WAITOK | M_ZERO); 2525 tmp_data2 = malloc(sizeof(struct witness_lock_order_data), M_TEMP, 2526 M_WAITOK | M_ZERO); 2527 stack_zero(&tmp_data1->wlod_stack); 2528 stack_zero(&tmp_data2->wlod_stack); 2529 2530 restart: 2531 mtx_lock_spin(&w_mtx); 2532 generation = w_generation; 2533 mtx_unlock_spin(&w_mtx); 2534 sbuf_printf(sb, "Number of known direct relationships is %d\n", 2535 w_lohash.wloh_count); 2536 for (i = 1; i < w_max_used_index; i++) { 2537 mtx_lock_spin(&w_mtx); 2538 if (generation != w_generation) { 2539 mtx_unlock_spin(&w_mtx); 2540 2541 /* The graph has changed, try again. */ 2542 req->oldidx = 0; 2543 sbuf_clear(sb); 2544 goto restart; 2545 } 2546 2547 w1 = &w_data[i]; 2548 if (w1->w_reversed == 0) { 2549 mtx_unlock_spin(&w_mtx); 2550 continue; 2551 } 2552 2553 /* Copy w1 locally so we can release the spin lock. */ 2554 *tmp_w1 = *w1; 2555 mtx_unlock_spin(&w_mtx); 2556 2557 if (tmp_w1->w_reversed == 0) 2558 continue; 2559 for (j = 1; j < w_max_used_index; j++) { 2560 if ((w_rmatrix[i][j] & WITNESS_REVERSAL) == 0 || i > j) 2561 continue; 2562 2563 mtx_lock_spin(&w_mtx); 2564 if (generation != w_generation) { 2565 mtx_unlock_spin(&w_mtx); 2566 2567 /* The graph has changed, try again. */ 2568 req->oldidx = 0; 2569 sbuf_clear(sb); 2570 goto restart; 2571 } 2572 2573 w2 = &w_data[j]; 2574 data1 = witness_lock_order_get(w1, w2); 2575 data2 = witness_lock_order_get(w2, w1); 2576 2577 /* 2578 * Copy information locally so we can release the 2579 * spin lock. 2580 */ 2581 *tmp_w2 = *w2; 2582 w_rmatrix1 = (unsigned int)w_rmatrix[i][j]; 2583 w_rmatrix2 = (unsigned int)w_rmatrix[j][i]; 2584 2585 if (data1) { 2586 stack_zero(&tmp_data1->wlod_stack); 2587 stack_copy(&data1->wlod_stack, 2588 &tmp_data1->wlod_stack); 2589 } 2590 if (data2 && data2 != data1) { 2591 stack_zero(&tmp_data2->wlod_stack); 2592 stack_copy(&data2->wlod_stack, 2593 &tmp_data2->wlod_stack); 2594 } 2595 mtx_unlock_spin(&w_mtx); 2596 2597 sbuf_printf(sb, 2598 "\nLock order reversal between \"%s\"(%s) and \"%s\"(%s)!\n", 2599 tmp_w1->w_name, tmp_w1->w_class->lc_name, 2600 tmp_w2->w_name, tmp_w2->w_class->lc_name); 2601 #if 0 2602 sbuf_printf(sb, 2603 "w_rmatrix[%s][%s] == %x, w_rmatrix[%s][%s] == %x\n", 2604 tmp_w1->name, tmp_w2->w_name, w_rmatrix1, 2605 tmp_w2->name, tmp_w1->w_name, w_rmatrix2); 2606 #endif 2607 if (data1) { 2608 sbuf_printf(sb, 2609 "Lock order \"%s\"(%s) -> \"%s\"(%s) first seen at:\n", 2610 tmp_w1->w_name, tmp_w1->w_class->lc_name, 2611 tmp_w2->w_name, tmp_w2->w_class->lc_name); 2612 stack_sbuf_print(sb, &tmp_data1->wlod_stack); 2613 sbuf_printf(sb, "\n"); 2614 } 2615 if (data2 && data2 != data1) { 2616 sbuf_printf(sb, 2617 "Lock order \"%s\"(%s) -> \"%s\"(%s) first seen at:\n", 2618 tmp_w2->w_name, tmp_w2->w_class->lc_name, 2619 tmp_w1->w_name, tmp_w1->w_class->lc_name); 2620 stack_sbuf_print(sb, &tmp_data2->wlod_stack); 2621 sbuf_printf(sb, "\n"); 2622 } 2623 } 2624 } 2625 mtx_lock_spin(&w_mtx); 2626 if (generation != w_generation) { 2627 mtx_unlock_spin(&w_mtx); 2628 2629 /* 2630 * The graph changed while we were printing stack data, 2631 * try again. 2632 */ 2633 req->oldidx = 0; 2634 sbuf_clear(sb); 2635 goto restart; 2636 } 2637 mtx_unlock_spin(&w_mtx); 2638 2639 /* Free temporary storage space. */ 2640 free(tmp_data1, M_TEMP); 2641 free(tmp_data2, M_TEMP); 2642 free(tmp_w1, M_TEMP); 2643 free(tmp_w2, M_TEMP); 2644 2645 sbuf_finish(sb); 2646 error = SYSCTL_OUT(req, sbuf_data(sb), sbuf_len(sb) + 1); 2647 sbuf_delete(sb); 2648 2649 return (error); 2650 } 2651 2652 static int 2653 sysctl_debug_witness_fullgraph(SYSCTL_HANDLER_ARGS) 2654 { 2655 struct witness *w; 2656 struct sbuf *sb; 2657 int error; 2658 2659 if (witness_watch < 1) { 2660 error = SYSCTL_OUT(req, w_notrunning, sizeof(w_notrunning)); 2661 return (error); 2662 } 2663 if (witness_cold) { 2664 error = SYSCTL_OUT(req, w_stillcold, sizeof(w_stillcold)); 2665 return (error); 2666 } 2667 error = 0; 2668 2669 error = sysctl_wire_old_buffer(req, 0); 2670 if (error != 0) 2671 return (error); 2672 sb = sbuf_new_for_sysctl(NULL, NULL, FULLGRAPH_SBUF_SIZE, req); 2673 if (sb == NULL) 2674 return (ENOMEM); 2675 sbuf_printf(sb, "\n"); 2676 2677 mtx_lock_spin(&w_mtx); 2678 STAILQ_FOREACH(w, &w_all, w_list) 2679 w->w_displayed = 0; 2680 STAILQ_FOREACH(w, &w_all, w_list) 2681 witness_add_fullgraph(sb, w); 2682 mtx_unlock_spin(&w_mtx); 2683 2684 /* 2685 * Close the sbuf and return to userland. 2686 */ 2687 error = sbuf_finish(sb); 2688 sbuf_delete(sb); 2689 2690 return (error); 2691 } 2692 2693 static int 2694 sysctl_debug_witness_watch(SYSCTL_HANDLER_ARGS) 2695 { 2696 int error, value; 2697 2698 value = witness_watch; 2699 error = sysctl_handle_int(oidp, &value, 0, req); 2700 if (error != 0 || req->newptr == NULL) 2701 return (error); 2702 if (value > 1 || value < -1 || 2703 (witness_watch == -1 && value != witness_watch)) 2704 return (EINVAL); 2705 witness_watch = value; 2706 return (0); 2707 } 2708 2709 static void 2710 witness_add_fullgraph(struct sbuf *sb, struct witness *w) 2711 { 2712 int i; 2713 2714 if (w->w_displayed != 0 || (w->w_file == NULL && w->w_line == 0)) 2715 return; 2716 w->w_displayed = 1; 2717 2718 WITNESS_INDEX_ASSERT(w->w_index); 2719 for (i = 1; i <= w_max_used_index; i++) { 2720 if (w_rmatrix[w->w_index][i] & WITNESS_PARENT) { 2721 sbuf_printf(sb, "\"%s\",\"%s\"\n", w->w_name, 2722 w_data[i].w_name); 2723 witness_add_fullgraph(sb, &w_data[i]); 2724 } 2725 } 2726 } 2727 2728 /* 2729 * A simple hash function. Takes a key pointer and a key size. If size == 0, 2730 * interprets the key as a string and reads until the null 2731 * terminator. Otherwise, reads the first size bytes. Returns an unsigned 32-bit 2732 * hash value computed from the key. 2733 */ 2734 static uint32_t 2735 witness_hash_djb2(const uint8_t *key, uint32_t size) 2736 { 2737 unsigned int hash = 5381; 2738 int i; 2739 2740 /* hash = hash * 33 + key[i] */ 2741 if (size) 2742 for (i = 0; i < size; i++) 2743 hash = ((hash << 5) + hash) + (unsigned int)key[i]; 2744 else 2745 for (i = 0; key[i] != 0; i++) 2746 hash = ((hash << 5) + hash) + (unsigned int)key[i]; 2747 2748 return (hash); 2749 } 2750 2751 2752 /* 2753 * Initializes the two witness hash tables. Called exactly once from 2754 * witness_initialize(). 2755 */ 2756 static void 2757 witness_init_hash_tables(void) 2758 { 2759 int i; 2760 2761 MPASS(witness_cold); 2762 2763 /* Initialize the hash tables. */ 2764 for (i = 0; i < WITNESS_HASH_SIZE; i++) 2765 w_hash.wh_array[i] = NULL; 2766 2767 w_hash.wh_size = WITNESS_HASH_SIZE; 2768 w_hash.wh_count = 0; 2769 2770 /* Initialize the lock order data hash. */ 2771 w_lofree = NULL; 2772 for (i = 0; i < WITNESS_LO_DATA_COUNT; i++) { 2773 memset(&w_lodata[i], 0, sizeof(w_lodata[i])); 2774 w_lodata[i].wlod_next = w_lofree; 2775 w_lofree = &w_lodata[i]; 2776 } 2777 w_lohash.wloh_size = WITNESS_LO_HASH_SIZE; 2778 w_lohash.wloh_count = 0; 2779 for (i = 0; i < WITNESS_LO_HASH_SIZE; i++) 2780 w_lohash.wloh_array[i] = NULL; 2781 } 2782 2783 static struct witness * 2784 witness_hash_get(const char *key) 2785 { 2786 struct witness *w; 2787 uint32_t hash; 2788 2789 MPASS(key != NULL); 2790 if (witness_cold == 0) 2791 mtx_assert(&w_mtx, MA_OWNED); 2792 hash = witness_hash_djb2(key, 0) % w_hash.wh_size; 2793 w = w_hash.wh_array[hash]; 2794 while (w != NULL) { 2795 if (strcmp(w->w_name, key) == 0) 2796 goto out; 2797 w = w->w_hash_next; 2798 } 2799 2800 out: 2801 return (w); 2802 } 2803 2804 static void 2805 witness_hash_put(struct witness *w) 2806 { 2807 uint32_t hash; 2808 2809 MPASS(w != NULL); 2810 MPASS(w->w_name != NULL); 2811 if (witness_cold == 0) 2812 mtx_assert(&w_mtx, MA_OWNED); 2813 KASSERT(witness_hash_get(w->w_name) == NULL, 2814 ("%s: trying to add a hash entry that already exists!", __func__)); 2815 KASSERT(w->w_hash_next == NULL, 2816 ("%s: w->w_hash_next != NULL", __func__)); 2817 2818 hash = witness_hash_djb2(w->w_name, 0) % w_hash.wh_size; 2819 w->w_hash_next = w_hash.wh_array[hash]; 2820 w_hash.wh_array[hash] = w; 2821 w_hash.wh_count++; 2822 } 2823 2824 2825 static struct witness_lock_order_data * 2826 witness_lock_order_get(struct witness *parent, struct witness *child) 2827 { 2828 struct witness_lock_order_data *data = NULL; 2829 struct witness_lock_order_key key; 2830 unsigned int hash; 2831 2832 MPASS(parent != NULL && child != NULL); 2833 key.from = parent->w_index; 2834 key.to = child->w_index; 2835 WITNESS_INDEX_ASSERT(key.from); 2836 WITNESS_INDEX_ASSERT(key.to); 2837 if ((w_rmatrix[parent->w_index][child->w_index] 2838 & WITNESS_LOCK_ORDER_KNOWN) == 0) 2839 goto out; 2840 2841 hash = witness_hash_djb2((const char*)&key, 2842 sizeof(key)) % w_lohash.wloh_size; 2843 data = w_lohash.wloh_array[hash]; 2844 while (data != NULL) { 2845 if (witness_lock_order_key_equal(&data->wlod_key, &key)) 2846 break; 2847 data = data->wlod_next; 2848 } 2849 2850 out: 2851 return (data); 2852 } 2853 2854 /* 2855 * Verify that parent and child have a known relationship, are not the same, 2856 * and child is actually a child of parent. This is done without w_mtx 2857 * to avoid contention in the common case. 2858 */ 2859 static int 2860 witness_lock_order_check(struct witness *parent, struct witness *child) 2861 { 2862 2863 if (parent != child && 2864 w_rmatrix[parent->w_index][child->w_index] 2865 & WITNESS_LOCK_ORDER_KNOWN && 2866 isitmychild(parent, child)) 2867 return (1); 2868 2869 return (0); 2870 } 2871 2872 static int 2873 witness_lock_order_add(struct witness *parent, struct witness *child) 2874 { 2875 struct witness_lock_order_data *data = NULL; 2876 struct witness_lock_order_key key; 2877 unsigned int hash; 2878 2879 MPASS(parent != NULL && child != NULL); 2880 key.from = parent->w_index; 2881 key.to = child->w_index; 2882 WITNESS_INDEX_ASSERT(key.from); 2883 WITNESS_INDEX_ASSERT(key.to); 2884 if (w_rmatrix[parent->w_index][child->w_index] 2885 & WITNESS_LOCK_ORDER_KNOWN) 2886 return (1); 2887 2888 hash = witness_hash_djb2((const char*)&key, 2889 sizeof(key)) % w_lohash.wloh_size; 2890 w_rmatrix[parent->w_index][child->w_index] |= WITNESS_LOCK_ORDER_KNOWN; 2891 data = w_lofree; 2892 if (data == NULL) 2893 return (0); 2894 w_lofree = data->wlod_next; 2895 data->wlod_next = w_lohash.wloh_array[hash]; 2896 data->wlod_key = key; 2897 w_lohash.wloh_array[hash] = data; 2898 w_lohash.wloh_count++; 2899 stack_zero(&data->wlod_stack); 2900 stack_save(&data->wlod_stack); 2901 return (1); 2902 } 2903 2904 /* Call this whenver the structure of the witness graph changes. */ 2905 static void 2906 witness_increment_graph_generation(void) 2907 { 2908 2909 if (witness_cold == 0) 2910 mtx_assert(&w_mtx, MA_OWNED); 2911 w_generation++; 2912 } 2913 2914 #ifdef KDB 2915 static void 2916 _witness_debugger(int cond, const char *msg) 2917 { 2918 2919 if (witness_trace && cond) 2920 kdb_backtrace(); 2921 if (witness_kdb && cond) 2922 kdb_enter(KDB_WHY_WITNESS, msg); 2923 } 2924 #endif 2925