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 #define WITNESS_COUNT 1024 136 #define WITNESS_CHILDCOUNT (WITNESS_COUNT * 4) 137 #define WITNESS_HASH_SIZE 251 /* Prime, gives load factor < 2 */ 138 #define WITNESS_PENDLIST 1024 139 140 /* Allocate 256 KB of stack data space */ 141 #define WITNESS_LO_DATA_COUNT 2048 142 143 /* Prime, gives load factor of ~2 at full load */ 144 #define WITNESS_LO_HASH_SIZE 1021 145 146 /* 147 * XXX: This is somewhat bogus, as we assume here that at most 2048 threads 148 * will hold LOCK_NCHILDREN locks. We handle failure ok, and we should 149 * probably be safe for the most part, but it's still a SWAG. 150 */ 151 #define LOCK_NCHILDREN 5 152 #define LOCK_CHILDCOUNT 2048 153 154 #define MAX_W_NAME 64 155 156 #define BADSTACK_SBUF_SIZE (256 * WITNESS_COUNT) 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_empty(const struct witness_lock_order_key *key) 309 { 310 311 return (key->from == 0 && key->to == 0); 312 } 313 314 static __inline int 315 witness_lock_order_key_equal(const struct witness_lock_order_key *a, 316 const struct witness_lock_order_key *b) 317 { 318 319 return (a->from == b->from && a->to == b->to); 320 } 321 322 static int _isitmyx(struct witness *w1, struct witness *w2, int rmask, 323 const char *fname); 324 #ifdef KDB 325 static void _witness_debugger(int cond, const char *msg); 326 #endif 327 static void adopt(struct witness *parent, struct witness *child); 328 #ifdef BLESSING 329 static int blessed(struct witness *, struct witness *); 330 #endif 331 static void depart(struct witness *w); 332 static struct witness *enroll(const char *description, 333 struct lock_class *lock_class); 334 static struct lock_instance *find_instance(struct lock_list_entry *list, 335 const struct lock_object *lock); 336 static int isitmychild(struct witness *parent, struct witness *child); 337 static int isitmydescendant(struct witness *parent, struct witness *child); 338 static void itismychild(struct witness *parent, struct witness *child); 339 static int sysctl_debug_witness_badstacks(SYSCTL_HANDLER_ARGS); 340 static int sysctl_debug_witness_watch(SYSCTL_HANDLER_ARGS); 341 static int sysctl_debug_witness_fullgraph(SYSCTL_HANDLER_ARGS); 342 static void witness_add_fullgraph(struct sbuf *sb, struct witness *parent); 343 #ifdef DDB 344 static void witness_ddb_compute_levels(void); 345 static void witness_ddb_display(int(*)(const char *fmt, ...)); 346 static void witness_ddb_display_descendants(int(*)(const char *fmt, ...), 347 struct witness *, int indent); 348 static void witness_ddb_display_list(int(*prnt)(const char *fmt, ...), 349 struct witness_list *list); 350 static void witness_ddb_level_descendants(struct witness *parent, int l); 351 static void witness_ddb_list(struct thread *td); 352 #endif 353 static void witness_free(struct witness *m); 354 static struct witness *witness_get(void); 355 static uint32_t witness_hash_djb2(const uint8_t *key, uint32_t size); 356 static struct witness *witness_hash_get(const char *key); 357 static void witness_hash_put(struct witness *w); 358 static void witness_init_hash_tables(void); 359 static void witness_increment_graph_generation(void); 360 static void witness_lock_list_free(struct lock_list_entry *lle); 361 static struct lock_list_entry *witness_lock_list_get(void); 362 static int witness_lock_order_add(struct witness *parent, 363 struct witness *child); 364 static int witness_lock_order_check(struct witness *parent, 365 struct witness *child); 366 static struct witness_lock_order_data *witness_lock_order_get( 367 struct witness *parent, 368 struct witness *child); 369 static void witness_list_lock(struct lock_instance *instance, 370 int (*prnt)(const char *fmt, ...)); 371 static void witness_setflag(struct lock_object *lock, int flag, int set); 372 373 #ifdef KDB 374 #define witness_debugger(c) _witness_debugger(c, __func__) 375 #else 376 #define witness_debugger(c) 377 #endif 378 379 static SYSCTL_NODE(_debug, OID_AUTO, witness, CTLFLAG_RW, NULL, 380 "Witness Locking"); 381 382 /* 383 * If set to 0, lock order checking is disabled. If set to -1, 384 * witness is completely disabled. Otherwise witness performs full 385 * lock order checking for all locks. At runtime, lock order checking 386 * may be toggled. However, witness cannot be reenabled once it is 387 * completely disabled. 388 */ 389 static int witness_watch = 1; 390 TUNABLE_INT("debug.witness.watch", &witness_watch); 391 SYSCTL_PROC(_debug_witness, OID_AUTO, watch, CTLFLAG_RW | CTLTYPE_INT, NULL, 0, 392 sysctl_debug_witness_watch, "I", "witness is watching lock operations"); 393 394 #ifdef KDB 395 /* 396 * When KDB is enabled and witness_kdb is 1, it will cause the system 397 * to drop into kdebug() when: 398 * - a lock hierarchy violation occurs 399 * - locks are held when going to sleep. 400 */ 401 #ifdef WITNESS_KDB 402 int witness_kdb = 1; 403 #else 404 int witness_kdb = 0; 405 #endif 406 TUNABLE_INT("debug.witness.kdb", &witness_kdb); 407 SYSCTL_INT(_debug_witness, OID_AUTO, kdb, CTLFLAG_RW, &witness_kdb, 0, ""); 408 409 /* 410 * When KDB is enabled and witness_trace is 1, it will cause the system 411 * to print a stack trace: 412 * - a lock hierarchy violation occurs 413 * - locks are held when going to sleep. 414 */ 415 int witness_trace = 1; 416 TUNABLE_INT("debug.witness.trace", &witness_trace); 417 SYSCTL_INT(_debug_witness, OID_AUTO, trace, CTLFLAG_RW, &witness_trace, 0, ""); 418 #endif /* KDB */ 419 420 #ifdef WITNESS_SKIPSPIN 421 int witness_skipspin = 1; 422 #else 423 int witness_skipspin = 0; 424 #endif 425 TUNABLE_INT("debug.witness.skipspin", &witness_skipspin); 426 SYSCTL_INT(_debug_witness, OID_AUTO, skipspin, CTLFLAG_RDTUN, &witness_skipspin, 427 0, ""); 428 429 /* 430 * Call this to print out the relations between locks. 431 */ 432 SYSCTL_PROC(_debug_witness, OID_AUTO, fullgraph, CTLTYPE_STRING | CTLFLAG_RD, 433 NULL, 0, sysctl_debug_witness_fullgraph, "A", "Show locks relation graphs"); 434 435 /* 436 * Call this to print out the witness faulty stacks. 437 */ 438 SYSCTL_PROC(_debug_witness, OID_AUTO, badstacks, CTLTYPE_STRING | CTLFLAG_RD, 439 NULL, 0, sysctl_debug_witness_badstacks, "A", "Show bad witness stacks"); 440 441 static struct mtx w_mtx; 442 443 /* w_list */ 444 static struct witness_list w_free = STAILQ_HEAD_INITIALIZER(w_free); 445 static struct witness_list w_all = STAILQ_HEAD_INITIALIZER(w_all); 446 447 /* w_typelist */ 448 static struct witness_list w_spin = STAILQ_HEAD_INITIALIZER(w_spin); 449 static struct witness_list w_sleep = STAILQ_HEAD_INITIALIZER(w_sleep); 450 451 /* lock list */ 452 static struct lock_list_entry *w_lock_list_free = NULL; 453 static struct witness_pendhelp pending_locks[WITNESS_PENDLIST]; 454 static u_int pending_cnt; 455 456 static int w_free_cnt, w_spin_cnt, w_sleep_cnt; 457 SYSCTL_INT(_debug_witness, OID_AUTO, free_cnt, CTLFLAG_RD, &w_free_cnt, 0, ""); 458 SYSCTL_INT(_debug_witness, OID_AUTO, spin_cnt, CTLFLAG_RD, &w_spin_cnt, 0, ""); 459 SYSCTL_INT(_debug_witness, OID_AUTO, sleep_cnt, CTLFLAG_RD, &w_sleep_cnt, 0, 460 ""); 461 462 static struct witness *w_data; 463 static uint8_t w_rmatrix[WITNESS_COUNT+1][WITNESS_COUNT+1]; 464 static struct lock_list_entry w_locklistdata[LOCK_CHILDCOUNT]; 465 static struct witness_hash w_hash; /* The witness hash table. */ 466 467 /* The lock order data hash */ 468 static struct witness_lock_order_data w_lodata[WITNESS_LO_DATA_COUNT]; 469 static struct witness_lock_order_data *w_lofree = NULL; 470 static struct witness_lock_order_hash w_lohash; 471 static int w_max_used_index = 0; 472 static unsigned int w_generation = 0; 473 static const char w_notrunning[] = "Witness not running\n"; 474 static const char w_stillcold[] = "Witness is still cold\n"; 475 476 477 static struct witness_order_list_entry order_lists[] = { 478 /* 479 * sx locks 480 */ 481 { "proctree", &lock_class_sx }, 482 { "allproc", &lock_class_sx }, 483 { "allprison", &lock_class_sx }, 484 { NULL, NULL }, 485 /* 486 * Various mutexes 487 */ 488 { "Giant", &lock_class_mtx_sleep }, 489 { "pipe mutex", &lock_class_mtx_sleep }, 490 { "sigio lock", &lock_class_mtx_sleep }, 491 { "process group", &lock_class_mtx_sleep }, 492 { "process lock", &lock_class_mtx_sleep }, 493 { "session", &lock_class_mtx_sleep }, 494 { "uidinfo hash", &lock_class_rw }, 495 #ifdef HWPMC_HOOKS 496 { "pmc-sleep", &lock_class_mtx_sleep }, 497 #endif 498 { "time lock", &lock_class_mtx_sleep }, 499 { NULL, NULL }, 500 /* 501 * Sockets 502 */ 503 { "accept", &lock_class_mtx_sleep }, 504 { "so_snd", &lock_class_mtx_sleep }, 505 { "so_rcv", &lock_class_mtx_sleep }, 506 { "sellck", &lock_class_mtx_sleep }, 507 { NULL, NULL }, 508 /* 509 * Routing 510 */ 511 { "so_rcv", &lock_class_mtx_sleep }, 512 { "radix node head", &lock_class_rw }, 513 { "rtentry", &lock_class_mtx_sleep }, 514 { "ifaddr", &lock_class_mtx_sleep }, 515 { NULL, NULL }, 516 /* 517 * IPv4 multicast: 518 * protocol locks before interface locks, after UDP locks. 519 */ 520 { "udpinp", &lock_class_rw }, 521 { "in_multi_mtx", &lock_class_mtx_sleep }, 522 { "igmp_mtx", &lock_class_mtx_sleep }, 523 { "if_addr_lock", &lock_class_rw }, 524 { NULL, NULL }, 525 /* 526 * IPv6 multicast: 527 * protocol locks before interface locks, after UDP locks. 528 */ 529 { "udpinp", &lock_class_rw }, 530 { "in6_multi_mtx", &lock_class_mtx_sleep }, 531 { "mld_mtx", &lock_class_mtx_sleep }, 532 { "if_addr_lock", &lock_class_rw }, 533 { NULL, NULL }, 534 /* 535 * UNIX Domain Sockets 536 */ 537 { "unp_global_rwlock", &lock_class_rw }, 538 { "unp_list_lock", &lock_class_mtx_sleep }, 539 { "unp", &lock_class_mtx_sleep }, 540 { "so_snd", &lock_class_mtx_sleep }, 541 { NULL, NULL }, 542 /* 543 * UDP/IP 544 */ 545 { "udp", &lock_class_rw }, 546 { "udpinp", &lock_class_rw }, 547 { "so_snd", &lock_class_mtx_sleep }, 548 { NULL, NULL }, 549 /* 550 * TCP/IP 551 */ 552 { "tcp", &lock_class_rw }, 553 { "tcpinp", &lock_class_rw }, 554 { "so_snd", &lock_class_mtx_sleep }, 555 { NULL, NULL }, 556 /* 557 * netatalk 558 */ 559 { "ddp_list_mtx", &lock_class_mtx_sleep }, 560 { "ddp_mtx", &lock_class_mtx_sleep }, 561 { NULL, NULL }, 562 /* 563 * BPF 564 */ 565 { "bpf global lock", &lock_class_mtx_sleep }, 566 { "bpf interface lock", &lock_class_rw }, 567 { "bpf cdev lock", &lock_class_mtx_sleep }, 568 { NULL, NULL }, 569 /* 570 * NFS server 571 */ 572 { "nfsd_mtx", &lock_class_mtx_sleep }, 573 { "so_snd", &lock_class_mtx_sleep }, 574 { NULL, NULL }, 575 576 /* 577 * IEEE 802.11 578 */ 579 { "802.11 com lock", &lock_class_mtx_sleep}, 580 { NULL, NULL }, 581 /* 582 * Network drivers 583 */ 584 { "network driver", &lock_class_mtx_sleep}, 585 { NULL, NULL }, 586 587 /* 588 * Netgraph 589 */ 590 { "ng_node", &lock_class_mtx_sleep }, 591 { "ng_worklist", &lock_class_mtx_sleep }, 592 { NULL, NULL }, 593 /* 594 * CDEV 595 */ 596 { "vm map (system)", &lock_class_mtx_sleep }, 597 { "vm page queue", &lock_class_mtx_sleep }, 598 { "vnode interlock", &lock_class_mtx_sleep }, 599 { "cdev", &lock_class_mtx_sleep }, 600 { NULL, NULL }, 601 /* 602 * VM 603 */ 604 { "vm map (user)", &lock_class_sx }, 605 { "vm object", &lock_class_rw }, 606 { "vm page", &lock_class_mtx_sleep }, 607 { "vm page queue", &lock_class_mtx_sleep }, 608 { "pmap pv global", &lock_class_rw }, 609 { "pmap", &lock_class_mtx_sleep }, 610 { "pmap pv list", &lock_class_rw }, 611 { "vm page free queue", &lock_class_mtx_sleep }, 612 { NULL, NULL }, 613 /* 614 * kqueue/VFS interaction 615 */ 616 { "kqueue", &lock_class_mtx_sleep }, 617 { "struct mount mtx", &lock_class_mtx_sleep }, 618 { "vnode interlock", &lock_class_mtx_sleep }, 619 { NULL, NULL }, 620 /* 621 * ZFS locking 622 */ 623 { "dn->dn_mtx", &lock_class_sx }, 624 { "dr->dt.di.dr_mtx", &lock_class_sx }, 625 { "db->db_mtx", &lock_class_sx }, 626 { NULL, NULL }, 627 /* 628 * spin locks 629 */ 630 #ifdef SMP 631 { "ap boot", &lock_class_mtx_spin }, 632 #endif 633 { "rm.mutex_mtx", &lock_class_mtx_spin }, 634 { "sio", &lock_class_mtx_spin }, 635 { "scrlock", &lock_class_mtx_spin }, 636 #ifdef __i386__ 637 { "cy", &lock_class_mtx_spin }, 638 #endif 639 #ifdef __sparc64__ 640 { "pcib_mtx", &lock_class_mtx_spin }, 641 { "rtc_mtx", &lock_class_mtx_spin }, 642 #endif 643 { "scc_hwmtx", &lock_class_mtx_spin }, 644 { "uart_hwmtx", &lock_class_mtx_spin }, 645 { "fast_taskqueue", &lock_class_mtx_spin }, 646 { "intr table", &lock_class_mtx_spin }, 647 #ifdef HWPMC_HOOKS 648 { "pmc-per-proc", &lock_class_mtx_spin }, 649 #endif 650 { "process slock", &lock_class_mtx_spin }, 651 { "sleepq chain", &lock_class_mtx_spin }, 652 { "umtx lock", &lock_class_mtx_spin }, 653 { "rm_spinlock", &lock_class_mtx_spin }, 654 { "turnstile chain", &lock_class_mtx_spin }, 655 { "turnstile lock", &lock_class_mtx_spin }, 656 { "sched lock", &lock_class_mtx_spin }, 657 { "td_contested", &lock_class_mtx_spin }, 658 { "callout", &lock_class_mtx_spin }, 659 { "entropy harvest mutex", &lock_class_mtx_spin }, 660 { "syscons video lock", &lock_class_mtx_spin }, 661 #ifdef SMP 662 { "smp rendezvous", &lock_class_mtx_spin }, 663 #endif 664 #ifdef __powerpc__ 665 { "tlb0", &lock_class_mtx_spin }, 666 #endif 667 /* 668 * leaf locks 669 */ 670 { "intrcnt", &lock_class_mtx_spin }, 671 { "icu", &lock_class_mtx_spin }, 672 #ifdef __i386__ 673 { "allpmaps", &lock_class_mtx_spin }, 674 { "descriptor tables", &lock_class_mtx_spin }, 675 #endif 676 { "clk", &lock_class_mtx_spin }, 677 { "cpuset", &lock_class_mtx_spin }, 678 { "mprof lock", &lock_class_mtx_spin }, 679 { "zombie lock", &lock_class_mtx_spin }, 680 { "ALD Queue", &lock_class_mtx_spin }, 681 #ifdef __ia64__ 682 { "MCA spin lock", &lock_class_mtx_spin }, 683 #endif 684 #if defined(__i386__) || defined(__amd64__) 685 { "pcicfg", &lock_class_mtx_spin }, 686 { "NDIS thread lock", &lock_class_mtx_spin }, 687 #endif 688 { "tw_osl_io_lock", &lock_class_mtx_spin }, 689 { "tw_osl_q_lock", &lock_class_mtx_spin }, 690 { "tw_cl_io_lock", &lock_class_mtx_spin }, 691 { "tw_cl_intr_lock", &lock_class_mtx_spin }, 692 { "tw_cl_gen_lock", &lock_class_mtx_spin }, 693 #ifdef HWPMC_HOOKS 694 { "pmc-leaf", &lock_class_mtx_spin }, 695 #endif 696 { "blocked lock", &lock_class_mtx_spin }, 697 { NULL, NULL }, 698 { NULL, NULL } 699 }; 700 701 #ifdef BLESSING 702 /* 703 * Pairs of locks which have been blessed 704 * Don't complain about order problems with blessed locks 705 */ 706 static struct witness_blessed blessed_list[] = { 707 }; 708 static int blessed_count = 709 sizeof(blessed_list) / sizeof(struct witness_blessed); 710 #endif 711 712 /* 713 * This global is set to 0 once it becomes safe to use the witness code. 714 */ 715 static int witness_cold = 1; 716 717 /* 718 * This global is set to 1 once the static lock orders have been enrolled 719 * so that a warning can be issued for any spin locks enrolled later. 720 */ 721 static int witness_spin_warn = 0; 722 723 /* Trim useless garbage from filenames. */ 724 static const char * 725 fixup_filename(const char *file) 726 { 727 728 if (file == NULL) 729 return (NULL); 730 while (strncmp(file, "../", 3) == 0) 731 file += 3; 732 return (file); 733 } 734 735 /* 736 * The WITNESS-enabled diagnostic code. Note that the witness code does 737 * assume that the early boot is single-threaded at least until after this 738 * routine is completed. 739 */ 740 static void 741 witness_initialize(void *dummy __unused) 742 { 743 struct lock_object *lock; 744 struct witness_order_list_entry *order; 745 struct witness *w, *w1; 746 int i; 747 748 w_data = malloc(sizeof (struct witness) * WITNESS_COUNT, M_WITNESS, 749 M_NOWAIT | M_ZERO); 750 751 /* 752 * We have to release Giant before initializing its witness 753 * structure so that WITNESS doesn't get confused. 754 */ 755 mtx_unlock(&Giant); 756 mtx_assert(&Giant, MA_NOTOWNED); 757 758 CTR1(KTR_WITNESS, "%s: initializing witness", __func__); 759 mtx_init(&w_mtx, "witness lock", NULL, MTX_SPIN | MTX_QUIET | 760 MTX_NOWITNESS | MTX_NOPROFILE); 761 for (i = WITNESS_COUNT - 1; i >= 0; i--) { 762 w = &w_data[i]; 763 memset(w, 0, sizeof(*w)); 764 w_data[i].w_index = i; /* Witness index never changes. */ 765 witness_free(w); 766 } 767 KASSERT(STAILQ_FIRST(&w_free)->w_index == 0, 768 ("%s: Invalid list of free witness objects", __func__)); 769 770 /* Witness with index 0 is not used to aid in debugging. */ 771 STAILQ_REMOVE_HEAD(&w_free, w_list); 772 w_free_cnt--; 773 774 memset(w_rmatrix, 0, 775 (sizeof(**w_rmatrix) * (WITNESS_COUNT+1) * (WITNESS_COUNT+1))); 776 777 for (i = 0; i < LOCK_CHILDCOUNT; i++) 778 witness_lock_list_free(&w_locklistdata[i]); 779 witness_init_hash_tables(); 780 781 /* First add in all the specified order lists. */ 782 for (order = order_lists; order->w_name != NULL; order++) { 783 w = enroll(order->w_name, order->w_class); 784 if (w == NULL) 785 continue; 786 w->w_file = "order list"; 787 for (order++; order->w_name != NULL; order++) { 788 w1 = enroll(order->w_name, order->w_class); 789 if (w1 == NULL) 790 continue; 791 w1->w_file = "order list"; 792 itismychild(w, w1); 793 w = w1; 794 } 795 } 796 witness_spin_warn = 1; 797 798 /* Iterate through all locks and add them to witness. */ 799 for (i = 0; pending_locks[i].wh_lock != NULL; i++) { 800 lock = pending_locks[i].wh_lock; 801 KASSERT(lock->lo_flags & LO_WITNESS, 802 ("%s: lock %s is on pending list but not LO_WITNESS", 803 __func__, lock->lo_name)); 804 lock->lo_witness = enroll(pending_locks[i].wh_type, 805 LOCK_CLASS(lock)); 806 } 807 808 /* Mark the witness code as being ready for use. */ 809 witness_cold = 0; 810 811 mtx_lock(&Giant); 812 } 813 SYSINIT(witness_init, SI_SUB_WITNESS, SI_ORDER_FIRST, witness_initialize, 814 NULL); 815 816 void 817 witness_init(struct lock_object *lock, const char *type) 818 { 819 struct lock_class *class; 820 821 /* Various sanity checks. */ 822 class = LOCK_CLASS(lock); 823 if ((lock->lo_flags & LO_RECURSABLE) != 0 && 824 (class->lc_flags & LC_RECURSABLE) == 0) 825 kassert_panic("%s: lock (%s) %s can not be recursable", 826 __func__, class->lc_name, lock->lo_name); 827 if ((lock->lo_flags & LO_SLEEPABLE) != 0 && 828 (class->lc_flags & LC_SLEEPABLE) == 0) 829 kassert_panic("%s: lock (%s) %s can not be sleepable", 830 __func__, class->lc_name, lock->lo_name); 831 if ((lock->lo_flags & LO_UPGRADABLE) != 0 && 832 (class->lc_flags & LC_UPGRADABLE) == 0) 833 kassert_panic("%s: lock (%s) %s can not be upgradable", 834 __func__, class->lc_name, lock->lo_name); 835 836 /* 837 * If we shouldn't watch this lock, then just clear lo_witness. 838 * Otherwise, if witness_cold is set, then it is too early to 839 * enroll this lock, so defer it to witness_initialize() by adding 840 * it to the pending_locks list. If it is not too early, then enroll 841 * the lock now. 842 */ 843 if (witness_watch < 1 || panicstr != NULL || 844 (lock->lo_flags & LO_WITNESS) == 0) 845 lock->lo_witness = NULL; 846 else if (witness_cold) { 847 pending_locks[pending_cnt].wh_lock = lock; 848 pending_locks[pending_cnt++].wh_type = type; 849 if (pending_cnt > WITNESS_PENDLIST) 850 panic("%s: pending locks list is too small, " 851 "increase WITNESS_PENDLIST\n", 852 __func__); 853 } else 854 lock->lo_witness = enroll(type, class); 855 } 856 857 void 858 witness_destroy(struct lock_object *lock) 859 { 860 struct lock_class *class; 861 struct witness *w; 862 863 class = LOCK_CLASS(lock); 864 865 if (witness_cold) 866 panic("lock (%s) %s destroyed while witness_cold", 867 class->lc_name, lock->lo_name); 868 869 /* XXX: need to verify that no one holds the lock */ 870 if ((lock->lo_flags & LO_WITNESS) == 0 || lock->lo_witness == NULL) 871 return; 872 w = lock->lo_witness; 873 874 mtx_lock_spin(&w_mtx); 875 MPASS(w->w_refcount > 0); 876 w->w_refcount--; 877 878 if (w->w_refcount == 0) 879 depart(w); 880 mtx_unlock_spin(&w_mtx); 881 } 882 883 #ifdef DDB 884 static void 885 witness_ddb_compute_levels(void) 886 { 887 struct witness *w; 888 889 /* 890 * First clear all levels. 891 */ 892 STAILQ_FOREACH(w, &w_all, w_list) 893 w->w_ddb_level = -1; 894 895 /* 896 * Look for locks with no parents and level all their descendants. 897 */ 898 STAILQ_FOREACH(w, &w_all, w_list) { 899 900 /* If the witness has ancestors (is not a root), skip it. */ 901 if (w->w_num_ancestors > 0) 902 continue; 903 witness_ddb_level_descendants(w, 0); 904 } 905 } 906 907 static void 908 witness_ddb_level_descendants(struct witness *w, int l) 909 { 910 int i; 911 912 if (w->w_ddb_level >= l) 913 return; 914 915 w->w_ddb_level = l; 916 l++; 917 918 for (i = 1; i <= w_max_used_index; i++) { 919 if (w_rmatrix[w->w_index][i] & WITNESS_PARENT) 920 witness_ddb_level_descendants(&w_data[i], l); 921 } 922 } 923 924 static void 925 witness_ddb_display_descendants(int(*prnt)(const char *fmt, ...), 926 struct witness *w, int indent) 927 { 928 int i; 929 930 for (i = 0; i < indent; i++) 931 prnt(" "); 932 prnt("%s (type: %s, depth: %d, active refs: %d)", 933 w->w_name, w->w_class->lc_name, 934 w->w_ddb_level, w->w_refcount); 935 if (w->w_displayed) { 936 prnt(" -- (already displayed)\n"); 937 return; 938 } 939 w->w_displayed = 1; 940 if (w->w_file != NULL && w->w_line != 0) 941 prnt(" -- last acquired @ %s:%d\n", fixup_filename(w->w_file), 942 w->w_line); 943 else 944 prnt(" -- never acquired\n"); 945 indent++; 946 WITNESS_INDEX_ASSERT(w->w_index); 947 for (i = 1; i <= w_max_used_index; i++) { 948 if (db_pager_quit) 949 return; 950 if (w_rmatrix[w->w_index][i] & WITNESS_PARENT) 951 witness_ddb_display_descendants(prnt, &w_data[i], 952 indent); 953 } 954 } 955 956 static void 957 witness_ddb_display_list(int(*prnt)(const char *fmt, ...), 958 struct witness_list *list) 959 { 960 struct witness *w; 961 962 STAILQ_FOREACH(w, list, w_typelist) { 963 if (w->w_file == NULL || w->w_ddb_level > 0) 964 continue; 965 966 /* This lock has no anscestors - display its descendants. */ 967 witness_ddb_display_descendants(prnt, w, 0); 968 if (db_pager_quit) 969 return; 970 } 971 } 972 973 static void 974 witness_ddb_display(int(*prnt)(const char *fmt, ...)) 975 { 976 struct witness *w; 977 978 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); 979 witness_ddb_compute_levels(); 980 981 /* Clear all the displayed flags. */ 982 STAILQ_FOREACH(w, &w_all, w_list) 983 w->w_displayed = 0; 984 985 /* 986 * First, handle sleep locks which have been acquired at least 987 * once. 988 */ 989 prnt("Sleep locks:\n"); 990 witness_ddb_display_list(prnt, &w_sleep); 991 if (db_pager_quit) 992 return; 993 994 /* 995 * Now do spin locks which have been acquired at least once. 996 */ 997 prnt("\nSpin locks:\n"); 998 witness_ddb_display_list(prnt, &w_spin); 999 if (db_pager_quit) 1000 return; 1001 1002 /* 1003 * Finally, any locks which have not been acquired yet. 1004 */ 1005 prnt("\nLocks which were never acquired:\n"); 1006 STAILQ_FOREACH(w, &w_all, w_list) { 1007 if (w->w_file != NULL || w->w_refcount == 0) 1008 continue; 1009 prnt("%s (type: %s, depth: %d)\n", w->w_name, 1010 w->w_class->lc_name, w->w_ddb_level); 1011 if (db_pager_quit) 1012 return; 1013 } 1014 } 1015 #endif /* DDB */ 1016 1017 int 1018 witness_defineorder(struct lock_object *lock1, struct lock_object *lock2) 1019 { 1020 1021 if (witness_watch == -1 || panicstr != NULL) 1022 return (0); 1023 1024 /* Require locks that witness knows about. */ 1025 if (lock1 == NULL || lock1->lo_witness == NULL || lock2 == NULL || 1026 lock2->lo_witness == NULL) 1027 return (EINVAL); 1028 1029 mtx_assert(&w_mtx, MA_NOTOWNED); 1030 mtx_lock_spin(&w_mtx); 1031 1032 /* 1033 * If we already have either an explicit or implied lock order that 1034 * is the other way around, then return an error. 1035 */ 1036 if (witness_watch && 1037 isitmydescendant(lock2->lo_witness, lock1->lo_witness)) { 1038 mtx_unlock_spin(&w_mtx); 1039 return (EDOOFUS); 1040 } 1041 1042 /* Try to add the new order. */ 1043 CTR3(KTR_WITNESS, "%s: adding %s as a child of %s", __func__, 1044 lock2->lo_witness->w_name, lock1->lo_witness->w_name); 1045 itismychild(lock1->lo_witness, lock2->lo_witness); 1046 mtx_unlock_spin(&w_mtx); 1047 return (0); 1048 } 1049 1050 void 1051 witness_checkorder(struct lock_object *lock, int flags, const char *file, 1052 int line, struct lock_object *interlock) 1053 { 1054 struct lock_list_entry *lock_list, *lle; 1055 struct lock_instance *lock1, *lock2, *plock; 1056 struct lock_class *class, *iclass; 1057 struct witness *w, *w1; 1058 struct thread *td; 1059 int i, j; 1060 1061 if (witness_cold || witness_watch < 1 || lock->lo_witness == NULL || 1062 panicstr != NULL) 1063 return; 1064 1065 w = lock->lo_witness; 1066 class = LOCK_CLASS(lock); 1067 td = curthread; 1068 1069 if (class->lc_flags & LC_SLEEPLOCK) { 1070 1071 /* 1072 * Since spin locks include a critical section, this check 1073 * implicitly enforces a lock order of all sleep locks before 1074 * all spin locks. 1075 */ 1076 if (td->td_critnest != 0 && !kdb_active) 1077 kassert_panic("acquiring blockable sleep lock with " 1078 "spinlock or critical section held (%s) %s @ %s:%d", 1079 class->lc_name, lock->lo_name, 1080 fixup_filename(file), line); 1081 1082 /* 1083 * If this is the first lock acquired then just return as 1084 * no order checking is needed. 1085 */ 1086 lock_list = td->td_sleeplocks; 1087 if (lock_list == NULL || lock_list->ll_count == 0) 1088 return; 1089 } else { 1090 1091 /* 1092 * If this is the first lock, just return as no order 1093 * checking is needed. Avoid problems with thread 1094 * migration pinning the thread while checking if 1095 * spinlocks are held. If at least one spinlock is held 1096 * the thread is in a safe path and it is allowed to 1097 * unpin it. 1098 */ 1099 sched_pin(); 1100 lock_list = PCPU_GET(spinlocks); 1101 if (lock_list == NULL || lock_list->ll_count == 0) { 1102 sched_unpin(); 1103 return; 1104 } 1105 sched_unpin(); 1106 } 1107 1108 /* 1109 * Check to see if we are recursing on a lock we already own. If 1110 * so, make sure that we don't mismatch exclusive and shared lock 1111 * acquires. 1112 */ 1113 lock1 = find_instance(lock_list, lock); 1114 if (lock1 != NULL) { 1115 if ((lock1->li_flags & LI_EXCLUSIVE) != 0 && 1116 (flags & LOP_EXCLUSIVE) == 0) { 1117 printf("shared lock of (%s) %s @ %s:%d\n", 1118 class->lc_name, lock->lo_name, 1119 fixup_filename(file), line); 1120 printf("while exclusively locked from %s:%d\n", 1121 fixup_filename(lock1->li_file), lock1->li_line); 1122 kassert_panic("excl->share"); 1123 } 1124 if ((lock1->li_flags & LI_EXCLUSIVE) == 0 && 1125 (flags & LOP_EXCLUSIVE) != 0) { 1126 printf("exclusive lock of (%s) %s @ %s:%d\n", 1127 class->lc_name, lock->lo_name, 1128 fixup_filename(file), line); 1129 printf("while share locked from %s:%d\n", 1130 fixup_filename(lock1->li_file), lock1->li_line); 1131 kassert_panic("share->excl"); 1132 } 1133 return; 1134 } 1135 1136 /* Warn if the interlock is not locked exactly once. */ 1137 if (interlock != NULL) { 1138 iclass = LOCK_CLASS(interlock); 1139 lock1 = find_instance(lock_list, interlock); 1140 if (lock1 == NULL) 1141 kassert_panic("interlock (%s) %s not locked @ %s:%d", 1142 iclass->lc_name, interlock->lo_name, 1143 fixup_filename(file), line); 1144 else if ((lock1->li_flags & LI_RECURSEMASK) != 0) 1145 kassert_panic("interlock (%s) %s recursed @ %s:%d", 1146 iclass->lc_name, interlock->lo_name, 1147 fixup_filename(file), line); 1148 } 1149 1150 /* 1151 * Find the previously acquired lock, but ignore interlocks. 1152 */ 1153 plock = &lock_list->ll_children[lock_list->ll_count - 1]; 1154 if (interlock != NULL && plock->li_lock == interlock) { 1155 if (lock_list->ll_count > 1) 1156 plock = 1157 &lock_list->ll_children[lock_list->ll_count - 2]; 1158 else { 1159 lle = lock_list->ll_next; 1160 1161 /* 1162 * The interlock is the only lock we hold, so 1163 * simply return. 1164 */ 1165 if (lle == NULL) 1166 return; 1167 plock = &lle->ll_children[lle->ll_count - 1]; 1168 } 1169 } 1170 1171 /* 1172 * Try to perform most checks without a lock. If this succeeds we 1173 * can skip acquiring the lock and return success. 1174 */ 1175 w1 = plock->li_lock->lo_witness; 1176 if (witness_lock_order_check(w1, w)) 1177 return; 1178 1179 /* 1180 * Check for duplicate locks of the same type. Note that we only 1181 * have to check for this on the last lock we just acquired. Any 1182 * other cases will be caught as lock order violations. 1183 */ 1184 mtx_lock_spin(&w_mtx); 1185 witness_lock_order_add(w1, w); 1186 if (w1 == w) { 1187 i = w->w_index; 1188 if (!(lock->lo_flags & LO_DUPOK) && !(flags & LOP_DUPOK) && 1189 !(w_rmatrix[i][i] & WITNESS_REVERSAL)) { 1190 w_rmatrix[i][i] |= WITNESS_REVERSAL; 1191 w->w_reversed = 1; 1192 mtx_unlock_spin(&w_mtx); 1193 printf( 1194 "acquiring duplicate lock of same type: \"%s\"\n", 1195 w->w_name); 1196 printf(" 1st %s @ %s:%d\n", plock->li_lock->lo_name, 1197 fixup_filename(plock->li_file), plock->li_line); 1198 printf(" 2nd %s @ %s:%d\n", lock->lo_name, 1199 fixup_filename(file), line); 1200 witness_debugger(1); 1201 } else 1202 mtx_unlock_spin(&w_mtx); 1203 return; 1204 } 1205 mtx_assert(&w_mtx, MA_OWNED); 1206 1207 /* 1208 * If we know that the lock we are acquiring comes after 1209 * the lock we most recently acquired in the lock order tree, 1210 * then there is no need for any further checks. 1211 */ 1212 if (isitmychild(w1, w)) 1213 goto out; 1214 1215 for (j = 0, lle = lock_list; lle != NULL; lle = lle->ll_next) { 1216 for (i = lle->ll_count - 1; i >= 0; i--, j++) { 1217 1218 MPASS(j < WITNESS_COUNT); 1219 lock1 = &lle->ll_children[i]; 1220 1221 /* 1222 * Ignore the interlock. 1223 */ 1224 if (interlock == lock1->li_lock) 1225 continue; 1226 1227 /* 1228 * If this lock doesn't undergo witness checking, 1229 * then skip it. 1230 */ 1231 w1 = lock1->li_lock->lo_witness; 1232 if (w1 == NULL) { 1233 KASSERT((lock1->li_lock->lo_flags & LO_WITNESS) == 0, 1234 ("lock missing witness structure")); 1235 continue; 1236 } 1237 1238 /* 1239 * If we are locking Giant and this is a sleepable 1240 * lock, then skip it. 1241 */ 1242 if ((lock1->li_lock->lo_flags & LO_SLEEPABLE) != 0 && 1243 lock == &Giant.lock_object) 1244 continue; 1245 1246 /* 1247 * If we are locking a sleepable lock and this lock 1248 * is Giant, then skip it. 1249 */ 1250 if ((lock->lo_flags & LO_SLEEPABLE) != 0 && 1251 lock1->li_lock == &Giant.lock_object) 1252 continue; 1253 1254 /* 1255 * If we are locking a sleepable lock and this lock 1256 * isn't sleepable, we want to treat it as a lock 1257 * order violation to enfore a general lock order of 1258 * sleepable locks before non-sleepable locks. 1259 */ 1260 if (((lock->lo_flags & LO_SLEEPABLE) != 0 && 1261 (lock1->li_lock->lo_flags & LO_SLEEPABLE) == 0)) 1262 goto reversal; 1263 1264 /* 1265 * If we are locking Giant and this is a non-sleepable 1266 * lock, then treat it as a reversal. 1267 */ 1268 if ((lock1->li_lock->lo_flags & LO_SLEEPABLE) == 0 && 1269 lock == &Giant.lock_object) 1270 goto reversal; 1271 1272 /* 1273 * Check the lock order hierarchy for a reveresal. 1274 */ 1275 if (!isitmydescendant(w, w1)) 1276 continue; 1277 reversal: 1278 1279 /* 1280 * We have a lock order violation, check to see if it 1281 * is allowed or has already been yelled about. 1282 */ 1283 #ifdef BLESSING 1284 1285 /* 1286 * If the lock order is blessed, just bail. We don't 1287 * look for other lock order violations though, which 1288 * may be a bug. 1289 */ 1290 if (blessed(w, w1)) 1291 goto out; 1292 #endif 1293 1294 /* Bail if this violation is known */ 1295 if (w_rmatrix[w1->w_index][w->w_index] & WITNESS_REVERSAL) 1296 goto out; 1297 1298 /* Record this as a violation */ 1299 w_rmatrix[w1->w_index][w->w_index] |= WITNESS_REVERSAL; 1300 w_rmatrix[w->w_index][w1->w_index] |= WITNESS_REVERSAL; 1301 w->w_reversed = w1->w_reversed = 1; 1302 witness_increment_graph_generation(); 1303 mtx_unlock_spin(&w_mtx); 1304 1305 #ifdef WITNESS_NO_VNODE 1306 /* 1307 * There are known LORs between VNODE locks. They are 1308 * not an indication of a bug. VNODE locks are flagged 1309 * as such (LO_IS_VNODE) and we don't yell if the LOR 1310 * is between 2 VNODE locks. 1311 */ 1312 if ((lock->lo_flags & LO_IS_VNODE) != 0 && 1313 (lock1->li_lock->lo_flags & LO_IS_VNODE) != 0) 1314 return; 1315 #endif 1316 1317 /* 1318 * Ok, yell about it. 1319 */ 1320 if (((lock->lo_flags & LO_SLEEPABLE) != 0 && 1321 (lock1->li_lock->lo_flags & LO_SLEEPABLE) == 0)) 1322 printf( 1323 "lock order reversal: (sleepable after non-sleepable)\n"); 1324 else if ((lock1->li_lock->lo_flags & LO_SLEEPABLE) == 0 1325 && lock == &Giant.lock_object) 1326 printf( 1327 "lock order reversal: (Giant after non-sleepable)\n"); 1328 else 1329 printf("lock order reversal:\n"); 1330 1331 /* 1332 * Try to locate an earlier lock with 1333 * witness w in our list. 1334 */ 1335 do { 1336 lock2 = &lle->ll_children[i]; 1337 MPASS(lock2->li_lock != NULL); 1338 if (lock2->li_lock->lo_witness == w) 1339 break; 1340 if (i == 0 && lle->ll_next != NULL) { 1341 lle = lle->ll_next; 1342 i = lle->ll_count - 1; 1343 MPASS(i >= 0 && i < LOCK_NCHILDREN); 1344 } else 1345 i--; 1346 } while (i >= 0); 1347 if (i < 0) { 1348 printf(" 1st %p %s (%s) @ %s:%d\n", 1349 lock1->li_lock, lock1->li_lock->lo_name, 1350 w1->w_name, fixup_filename(lock1->li_file), 1351 lock1->li_line); 1352 printf(" 2nd %p %s (%s) @ %s:%d\n", lock, 1353 lock->lo_name, w->w_name, 1354 fixup_filename(file), line); 1355 } else { 1356 printf(" 1st %p %s (%s) @ %s:%d\n", 1357 lock2->li_lock, lock2->li_lock->lo_name, 1358 lock2->li_lock->lo_witness->w_name, 1359 fixup_filename(lock2->li_file), 1360 lock2->li_line); 1361 printf(" 2nd %p %s (%s) @ %s:%d\n", 1362 lock1->li_lock, lock1->li_lock->lo_name, 1363 w1->w_name, fixup_filename(lock1->li_file), 1364 lock1->li_line); 1365 printf(" 3rd %p %s (%s) @ %s:%d\n", lock, 1366 lock->lo_name, w->w_name, 1367 fixup_filename(file), line); 1368 } 1369 witness_debugger(1); 1370 return; 1371 } 1372 } 1373 1374 /* 1375 * If requested, build a new lock order. However, don't build a new 1376 * relationship between a sleepable lock and Giant if it is in the 1377 * wrong direction. The correct lock order is that sleepable locks 1378 * always come before Giant. 1379 */ 1380 if (flags & LOP_NEWORDER && 1381 !(plock->li_lock == &Giant.lock_object && 1382 (lock->lo_flags & LO_SLEEPABLE) != 0)) { 1383 CTR3(KTR_WITNESS, "%s: adding %s as a child of %s", __func__, 1384 w->w_name, plock->li_lock->lo_witness->w_name); 1385 itismychild(plock->li_lock->lo_witness, w); 1386 } 1387 out: 1388 mtx_unlock_spin(&w_mtx); 1389 } 1390 1391 void 1392 witness_lock(struct lock_object *lock, int flags, const char *file, int line) 1393 { 1394 struct lock_list_entry **lock_list, *lle; 1395 struct lock_instance *instance; 1396 struct witness *w; 1397 struct thread *td; 1398 1399 if (witness_cold || witness_watch == -1 || lock->lo_witness == NULL || 1400 panicstr != NULL) 1401 return; 1402 w = lock->lo_witness; 1403 td = curthread; 1404 1405 /* Determine lock list for this lock. */ 1406 if (LOCK_CLASS(lock)->lc_flags & LC_SLEEPLOCK) 1407 lock_list = &td->td_sleeplocks; 1408 else 1409 lock_list = PCPU_PTR(spinlocks); 1410 1411 /* Check to see if we are recursing on a lock we already own. */ 1412 instance = find_instance(*lock_list, lock); 1413 if (instance != NULL) { 1414 instance->li_flags++; 1415 CTR4(KTR_WITNESS, "%s: pid %d recursed on %s r=%d", __func__, 1416 td->td_proc->p_pid, lock->lo_name, 1417 instance->li_flags & LI_RECURSEMASK); 1418 instance->li_file = file; 1419 instance->li_line = line; 1420 return; 1421 } 1422 1423 /* Update per-witness last file and line acquire. */ 1424 w->w_file = file; 1425 w->w_line = line; 1426 1427 /* Find the next open lock instance in the list and fill it. */ 1428 lle = *lock_list; 1429 if (lle == NULL || lle->ll_count == LOCK_NCHILDREN) { 1430 lle = witness_lock_list_get(); 1431 if (lle == NULL) 1432 return; 1433 lle->ll_next = *lock_list; 1434 CTR3(KTR_WITNESS, "%s: pid %d added lle %p", __func__, 1435 td->td_proc->p_pid, lle); 1436 *lock_list = lle; 1437 } 1438 instance = &lle->ll_children[lle->ll_count++]; 1439 instance->li_lock = lock; 1440 instance->li_line = line; 1441 instance->li_file = file; 1442 if ((flags & LOP_EXCLUSIVE) != 0) 1443 instance->li_flags = LI_EXCLUSIVE; 1444 else 1445 instance->li_flags = 0; 1446 CTR4(KTR_WITNESS, "%s: pid %d added %s as lle[%d]", __func__, 1447 td->td_proc->p_pid, lock->lo_name, lle->ll_count - 1); 1448 } 1449 1450 void 1451 witness_upgrade(struct lock_object *lock, int flags, const char *file, int line) 1452 { 1453 struct lock_instance *instance; 1454 struct lock_class *class; 1455 1456 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); 1457 if (lock->lo_witness == NULL || witness_watch == -1 || panicstr != NULL) 1458 return; 1459 class = LOCK_CLASS(lock); 1460 if (witness_watch) { 1461 if ((lock->lo_flags & LO_UPGRADABLE) == 0) 1462 kassert_panic( 1463 "upgrade of non-upgradable lock (%s) %s @ %s:%d", 1464 class->lc_name, lock->lo_name, 1465 fixup_filename(file), line); 1466 if ((class->lc_flags & LC_SLEEPLOCK) == 0) 1467 kassert_panic( 1468 "upgrade of non-sleep lock (%s) %s @ %s:%d", 1469 class->lc_name, lock->lo_name, 1470 fixup_filename(file), line); 1471 } 1472 instance = find_instance(curthread->td_sleeplocks, lock); 1473 if (instance == NULL) { 1474 kassert_panic("upgrade of unlocked lock (%s) %s @ %s:%d", 1475 class->lc_name, lock->lo_name, 1476 fixup_filename(file), line); 1477 return; 1478 } 1479 if (witness_watch) { 1480 if ((instance->li_flags & LI_EXCLUSIVE) != 0) 1481 kassert_panic( 1482 "upgrade of exclusive lock (%s) %s @ %s:%d", 1483 class->lc_name, lock->lo_name, 1484 fixup_filename(file), line); 1485 if ((instance->li_flags & LI_RECURSEMASK) != 0) 1486 kassert_panic( 1487 "upgrade of recursed lock (%s) %s r=%d @ %s:%d", 1488 class->lc_name, lock->lo_name, 1489 instance->li_flags & LI_RECURSEMASK, 1490 fixup_filename(file), line); 1491 } 1492 instance->li_flags |= LI_EXCLUSIVE; 1493 } 1494 1495 void 1496 witness_downgrade(struct lock_object *lock, int flags, const char *file, 1497 int line) 1498 { 1499 struct lock_instance *instance; 1500 struct lock_class *class; 1501 1502 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); 1503 if (lock->lo_witness == NULL || witness_watch == -1 || panicstr != NULL) 1504 return; 1505 class = LOCK_CLASS(lock); 1506 if (witness_watch) { 1507 if ((lock->lo_flags & LO_UPGRADABLE) == 0) 1508 kassert_panic( 1509 "downgrade of non-upgradable lock (%s) %s @ %s:%d", 1510 class->lc_name, lock->lo_name, 1511 fixup_filename(file), line); 1512 if ((class->lc_flags & LC_SLEEPLOCK) == 0) 1513 kassert_panic( 1514 "downgrade of non-sleep lock (%s) %s @ %s:%d", 1515 class->lc_name, lock->lo_name, 1516 fixup_filename(file), line); 1517 } 1518 instance = find_instance(curthread->td_sleeplocks, lock); 1519 if (instance == NULL) { 1520 kassert_panic("downgrade of unlocked lock (%s) %s @ %s:%d", 1521 class->lc_name, lock->lo_name, 1522 fixup_filename(file), line); 1523 return; 1524 } 1525 if (witness_watch) { 1526 if ((instance->li_flags & LI_EXCLUSIVE) == 0) 1527 kassert_panic( 1528 "downgrade of shared lock (%s) %s @ %s:%d", 1529 class->lc_name, lock->lo_name, 1530 fixup_filename(file), line); 1531 if ((instance->li_flags & LI_RECURSEMASK) != 0) 1532 kassert_panic( 1533 "downgrade of recursed lock (%s) %s r=%d @ %s:%d", 1534 class->lc_name, lock->lo_name, 1535 instance->li_flags & LI_RECURSEMASK, 1536 fixup_filename(file), line); 1537 } 1538 instance->li_flags &= ~LI_EXCLUSIVE; 1539 } 1540 1541 void 1542 witness_unlock(struct lock_object *lock, int flags, const char *file, int line) 1543 { 1544 struct lock_list_entry **lock_list, *lle; 1545 struct lock_instance *instance; 1546 struct lock_class *class; 1547 struct thread *td; 1548 register_t s; 1549 int i, j; 1550 1551 if (witness_cold || lock->lo_witness == NULL || panicstr != NULL) 1552 return; 1553 td = curthread; 1554 class = LOCK_CLASS(lock); 1555 1556 /* Find lock instance associated with this lock. */ 1557 if (class->lc_flags & LC_SLEEPLOCK) 1558 lock_list = &td->td_sleeplocks; 1559 else 1560 lock_list = PCPU_PTR(spinlocks); 1561 lle = *lock_list; 1562 for (; *lock_list != NULL; lock_list = &(*lock_list)->ll_next) 1563 for (i = 0; i < (*lock_list)->ll_count; i++) { 1564 instance = &(*lock_list)->ll_children[i]; 1565 if (instance->li_lock == lock) 1566 goto found; 1567 } 1568 1569 /* 1570 * When disabling WITNESS through witness_watch we could end up in 1571 * having registered locks in the td_sleeplocks queue. 1572 * We have to make sure we flush these queues, so just search for 1573 * eventual register locks and remove them. 1574 */ 1575 if (witness_watch > 0) { 1576 kassert_panic("lock (%s) %s not locked @ %s:%d", class->lc_name, 1577 lock->lo_name, fixup_filename(file), line); 1578 return; 1579 } else { 1580 return; 1581 } 1582 found: 1583 1584 /* First, check for shared/exclusive mismatches. */ 1585 if ((instance->li_flags & LI_EXCLUSIVE) != 0 && witness_watch > 0 && 1586 (flags & LOP_EXCLUSIVE) == 0) { 1587 printf("shared unlock of (%s) %s @ %s:%d\n", class->lc_name, 1588 lock->lo_name, fixup_filename(file), line); 1589 printf("while exclusively locked from %s:%d\n", 1590 fixup_filename(instance->li_file), instance->li_line); 1591 kassert_panic("excl->ushare"); 1592 } 1593 if ((instance->li_flags & LI_EXCLUSIVE) == 0 && witness_watch > 0 && 1594 (flags & LOP_EXCLUSIVE) != 0) { 1595 printf("exclusive unlock of (%s) %s @ %s:%d\n", class->lc_name, 1596 lock->lo_name, fixup_filename(file), line); 1597 printf("while share locked from %s:%d\n", 1598 fixup_filename(instance->li_file), 1599 instance->li_line); 1600 kassert_panic("share->uexcl"); 1601 } 1602 /* If we are recursed, unrecurse. */ 1603 if ((instance->li_flags & LI_RECURSEMASK) > 0) { 1604 CTR4(KTR_WITNESS, "%s: pid %d unrecursed on %s r=%d", __func__, 1605 td->td_proc->p_pid, instance->li_lock->lo_name, 1606 instance->li_flags); 1607 instance->li_flags--; 1608 return; 1609 } 1610 /* The lock is now being dropped, check for NORELEASE flag */ 1611 if ((instance->li_flags & LI_NORELEASE) != 0 && witness_watch > 0) { 1612 printf("forbidden unlock of (%s) %s @ %s:%d\n", class->lc_name, 1613 lock->lo_name, fixup_filename(file), line); 1614 kassert_panic("lock marked norelease"); 1615 } 1616 1617 /* Otherwise, remove this item from the list. */ 1618 s = intr_disable(); 1619 CTR4(KTR_WITNESS, "%s: pid %d removed %s from lle[%d]", __func__, 1620 td->td_proc->p_pid, instance->li_lock->lo_name, 1621 (*lock_list)->ll_count - 1); 1622 for (j = i; j < (*lock_list)->ll_count - 1; j++) 1623 (*lock_list)->ll_children[j] = 1624 (*lock_list)->ll_children[j + 1]; 1625 (*lock_list)->ll_count--; 1626 intr_restore(s); 1627 1628 /* 1629 * In order to reduce contention on w_mtx, we want to keep always an 1630 * head object into lists so that frequent allocation from the 1631 * free witness pool (and subsequent locking) is avoided. 1632 * In order to maintain the current code simple, when the head 1633 * object is totally unloaded it means also that we do not have 1634 * further objects in the list, so the list ownership needs to be 1635 * hand over to another object if the current head needs to be freed. 1636 */ 1637 if ((*lock_list)->ll_count == 0) { 1638 if (*lock_list == lle) { 1639 if (lle->ll_next == NULL) 1640 return; 1641 } else 1642 lle = *lock_list; 1643 *lock_list = lle->ll_next; 1644 CTR3(KTR_WITNESS, "%s: pid %d removed lle %p", __func__, 1645 td->td_proc->p_pid, lle); 1646 witness_lock_list_free(lle); 1647 } 1648 } 1649 1650 void 1651 witness_thread_exit(struct thread *td) 1652 { 1653 struct lock_list_entry *lle; 1654 int i, n; 1655 1656 lle = td->td_sleeplocks; 1657 if (lle == NULL || panicstr != NULL) 1658 return; 1659 if (lle->ll_count != 0) { 1660 for (n = 0; lle != NULL; lle = lle->ll_next) 1661 for (i = lle->ll_count - 1; i >= 0; i--) { 1662 if (n == 0) 1663 printf("Thread %p exiting with the following locks held:\n", 1664 td); 1665 n++; 1666 witness_list_lock(&lle->ll_children[i], printf); 1667 1668 } 1669 kassert_panic( 1670 "Thread %p cannot exit while holding sleeplocks\n", td); 1671 } 1672 witness_lock_list_free(lle); 1673 } 1674 1675 /* 1676 * Warn if any locks other than 'lock' are held. Flags can be passed in to 1677 * exempt Giant and sleepable locks from the checks as well. If any 1678 * non-exempt locks are held, then a supplied message is printed to the 1679 * console along with a list of the offending locks. If indicated in the 1680 * flags then a failure results in a panic as well. 1681 */ 1682 int 1683 witness_warn(int flags, struct lock_object *lock, const char *fmt, ...) 1684 { 1685 struct lock_list_entry *lock_list, *lle; 1686 struct lock_instance *lock1; 1687 struct thread *td; 1688 va_list ap; 1689 int i, n; 1690 1691 if (witness_cold || witness_watch < 1 || panicstr != NULL) 1692 return (0); 1693 n = 0; 1694 td = curthread; 1695 for (lle = td->td_sleeplocks; lle != NULL; lle = lle->ll_next) 1696 for (i = lle->ll_count - 1; i >= 0; i--) { 1697 lock1 = &lle->ll_children[i]; 1698 if (lock1->li_lock == lock) 1699 continue; 1700 if (flags & WARN_GIANTOK && 1701 lock1->li_lock == &Giant.lock_object) 1702 continue; 1703 if (flags & WARN_SLEEPOK && 1704 (lock1->li_lock->lo_flags & LO_SLEEPABLE) != 0) 1705 continue; 1706 if (n == 0) { 1707 va_start(ap, fmt); 1708 vprintf(fmt, ap); 1709 va_end(ap); 1710 printf(" with the following"); 1711 if (flags & WARN_SLEEPOK) 1712 printf(" non-sleepable"); 1713 printf(" locks held:\n"); 1714 } 1715 n++; 1716 witness_list_lock(lock1, printf); 1717 } 1718 1719 /* 1720 * Pin the thread in order to avoid problems with thread migration. 1721 * Once that all verifies are passed about spinlocks ownership, 1722 * the thread is in a safe path and it can be unpinned. 1723 */ 1724 sched_pin(); 1725 lock_list = PCPU_GET(spinlocks); 1726 if (lock_list != NULL && lock_list->ll_count != 0) { 1727 sched_unpin(); 1728 1729 /* 1730 * We should only have one spinlock and as long as 1731 * the flags cannot match for this locks class, 1732 * check if the first spinlock is the one curthread 1733 * should hold. 1734 */ 1735 lock1 = &lock_list->ll_children[lock_list->ll_count - 1]; 1736 if (lock_list->ll_count == 1 && lock_list->ll_next == NULL && 1737 lock1->li_lock == lock && n == 0) 1738 return (0); 1739 1740 va_start(ap, fmt); 1741 vprintf(fmt, ap); 1742 va_end(ap); 1743 printf(" with the following"); 1744 if (flags & WARN_SLEEPOK) 1745 printf(" non-sleepable"); 1746 printf(" locks held:\n"); 1747 n += witness_list_locks(&lock_list, printf); 1748 } else 1749 sched_unpin(); 1750 if (flags & WARN_PANIC && n) 1751 kassert_panic("%s", __func__); 1752 else 1753 witness_debugger(n); 1754 return (n); 1755 } 1756 1757 const char * 1758 witness_file(struct lock_object *lock) 1759 { 1760 struct witness *w; 1761 1762 if (witness_cold || witness_watch < 1 || lock->lo_witness == NULL) 1763 return ("?"); 1764 w = lock->lo_witness; 1765 return (w->w_file); 1766 } 1767 1768 int 1769 witness_line(struct lock_object *lock) 1770 { 1771 struct witness *w; 1772 1773 if (witness_cold || witness_watch < 1 || lock->lo_witness == NULL) 1774 return (0); 1775 w = lock->lo_witness; 1776 return (w->w_line); 1777 } 1778 1779 static struct witness * 1780 enroll(const char *description, struct lock_class *lock_class) 1781 { 1782 struct witness *w; 1783 struct witness_list *typelist; 1784 1785 MPASS(description != NULL); 1786 1787 if (witness_watch == -1 || panicstr != NULL) 1788 return (NULL); 1789 if ((lock_class->lc_flags & LC_SPINLOCK)) { 1790 if (witness_skipspin) 1791 return (NULL); 1792 else 1793 typelist = &w_spin; 1794 } else if ((lock_class->lc_flags & LC_SLEEPLOCK)) { 1795 typelist = &w_sleep; 1796 } else { 1797 kassert_panic("lock class %s is not sleep or spin", 1798 lock_class->lc_name); 1799 return (NULL); 1800 } 1801 1802 mtx_lock_spin(&w_mtx); 1803 w = witness_hash_get(description); 1804 if (w) 1805 goto found; 1806 if ((w = witness_get()) == NULL) 1807 return (NULL); 1808 MPASS(strlen(description) < MAX_W_NAME); 1809 strcpy(w->w_name, description); 1810 w->w_class = lock_class; 1811 w->w_refcount = 1; 1812 STAILQ_INSERT_HEAD(&w_all, w, w_list); 1813 if (lock_class->lc_flags & LC_SPINLOCK) { 1814 STAILQ_INSERT_HEAD(&w_spin, w, w_typelist); 1815 w_spin_cnt++; 1816 } else if (lock_class->lc_flags & LC_SLEEPLOCK) { 1817 STAILQ_INSERT_HEAD(&w_sleep, w, w_typelist); 1818 w_sleep_cnt++; 1819 } 1820 1821 /* Insert new witness into the hash */ 1822 witness_hash_put(w); 1823 witness_increment_graph_generation(); 1824 mtx_unlock_spin(&w_mtx); 1825 return (w); 1826 found: 1827 w->w_refcount++; 1828 mtx_unlock_spin(&w_mtx); 1829 if (lock_class != w->w_class) 1830 kassert_panic( 1831 "lock (%s) %s does not match earlier (%s) lock", 1832 description, lock_class->lc_name, 1833 w->w_class->lc_name); 1834 return (w); 1835 } 1836 1837 static void 1838 depart(struct witness *w) 1839 { 1840 struct witness_list *list; 1841 1842 MPASS(w->w_refcount == 0); 1843 if (w->w_class->lc_flags & LC_SLEEPLOCK) { 1844 list = &w_sleep; 1845 w_sleep_cnt--; 1846 } else { 1847 list = &w_spin; 1848 w_spin_cnt--; 1849 } 1850 /* 1851 * Set file to NULL as it may point into a loadable module. 1852 */ 1853 w->w_file = NULL; 1854 w->w_line = 0; 1855 witness_increment_graph_generation(); 1856 } 1857 1858 1859 static void 1860 adopt(struct witness *parent, struct witness *child) 1861 { 1862 int pi, ci, i, j; 1863 1864 if (witness_cold == 0) 1865 mtx_assert(&w_mtx, MA_OWNED); 1866 1867 /* If the relationship is already known, there's no work to be done. */ 1868 if (isitmychild(parent, child)) 1869 return; 1870 1871 /* When the structure of the graph changes, bump up the generation. */ 1872 witness_increment_graph_generation(); 1873 1874 /* 1875 * The hard part ... create the direct relationship, then propagate all 1876 * indirect relationships. 1877 */ 1878 pi = parent->w_index; 1879 ci = child->w_index; 1880 WITNESS_INDEX_ASSERT(pi); 1881 WITNESS_INDEX_ASSERT(ci); 1882 MPASS(pi != ci); 1883 w_rmatrix[pi][ci] |= WITNESS_PARENT; 1884 w_rmatrix[ci][pi] |= WITNESS_CHILD; 1885 1886 /* 1887 * If parent was not already an ancestor of child, 1888 * then we increment the descendant and ancestor counters. 1889 */ 1890 if ((w_rmatrix[pi][ci] & WITNESS_ANCESTOR) == 0) { 1891 parent->w_num_descendants++; 1892 child->w_num_ancestors++; 1893 } 1894 1895 /* 1896 * Find each ancestor of 'pi'. Note that 'pi' itself is counted as 1897 * an ancestor of 'pi' during this loop. 1898 */ 1899 for (i = 1; i <= w_max_used_index; i++) { 1900 if ((w_rmatrix[i][pi] & WITNESS_ANCESTOR_MASK) == 0 && 1901 (i != pi)) 1902 continue; 1903 1904 /* Find each descendant of 'i' and mark it as a descendant. */ 1905 for (j = 1; j <= w_max_used_index; j++) { 1906 1907 /* 1908 * Skip children that are already marked as 1909 * descendants of 'i'. 1910 */ 1911 if (w_rmatrix[i][j] & WITNESS_ANCESTOR_MASK) 1912 continue; 1913 1914 /* 1915 * We are only interested in descendants of 'ci'. Note 1916 * that 'ci' itself is counted as a descendant of 'ci'. 1917 */ 1918 if ((w_rmatrix[ci][j] & WITNESS_ANCESTOR_MASK) == 0 && 1919 (j != ci)) 1920 continue; 1921 w_rmatrix[i][j] |= WITNESS_ANCESTOR; 1922 w_rmatrix[j][i] |= WITNESS_DESCENDANT; 1923 w_data[i].w_num_descendants++; 1924 w_data[j].w_num_ancestors++; 1925 1926 /* 1927 * Make sure we aren't marking a node as both an 1928 * ancestor and descendant. We should have caught 1929 * this as a lock order reversal earlier. 1930 */ 1931 if ((w_rmatrix[i][j] & WITNESS_ANCESTOR_MASK) && 1932 (w_rmatrix[i][j] & WITNESS_DESCENDANT_MASK)) { 1933 printf("witness rmatrix paradox! [%d][%d]=%d " 1934 "both ancestor and descendant\n", 1935 i, j, w_rmatrix[i][j]); 1936 kdb_backtrace(); 1937 printf("Witness disabled.\n"); 1938 witness_watch = -1; 1939 } 1940 if ((w_rmatrix[j][i] & WITNESS_ANCESTOR_MASK) && 1941 (w_rmatrix[j][i] & WITNESS_DESCENDANT_MASK)) { 1942 printf("witness rmatrix paradox! [%d][%d]=%d " 1943 "both ancestor and descendant\n", 1944 j, i, w_rmatrix[j][i]); 1945 kdb_backtrace(); 1946 printf("Witness disabled.\n"); 1947 witness_watch = -1; 1948 } 1949 } 1950 } 1951 } 1952 1953 static void 1954 itismychild(struct witness *parent, struct witness *child) 1955 { 1956 int unlocked; 1957 1958 MPASS(child != NULL && parent != NULL); 1959 if (witness_cold == 0) 1960 mtx_assert(&w_mtx, MA_OWNED); 1961 1962 if (!witness_lock_type_equal(parent, child)) { 1963 if (witness_cold == 0) { 1964 unlocked = 1; 1965 mtx_unlock_spin(&w_mtx); 1966 } else { 1967 unlocked = 0; 1968 } 1969 kassert_panic( 1970 "%s: parent \"%s\" (%s) and child \"%s\" (%s) are not " 1971 "the same lock type", __func__, parent->w_name, 1972 parent->w_class->lc_name, child->w_name, 1973 child->w_class->lc_name); 1974 if (unlocked) 1975 mtx_lock_spin(&w_mtx); 1976 } 1977 adopt(parent, child); 1978 } 1979 1980 /* 1981 * Generic code for the isitmy*() functions. The rmask parameter is the 1982 * expected relationship of w1 to w2. 1983 */ 1984 static int 1985 _isitmyx(struct witness *w1, struct witness *w2, int rmask, const char *fname) 1986 { 1987 unsigned char r1, r2; 1988 int i1, i2; 1989 1990 i1 = w1->w_index; 1991 i2 = w2->w_index; 1992 WITNESS_INDEX_ASSERT(i1); 1993 WITNESS_INDEX_ASSERT(i2); 1994 r1 = w_rmatrix[i1][i2] & WITNESS_RELATED_MASK; 1995 r2 = w_rmatrix[i2][i1] & WITNESS_RELATED_MASK; 1996 1997 /* The flags on one better be the inverse of the flags on the other */ 1998 if (!((WITNESS_ATOD(r1) == r2 && WITNESS_DTOA(r2) == r1) || 1999 (WITNESS_DTOA(r1) == r2 && WITNESS_ATOD(r2) == r1))) { 2000 printf("%s: rmatrix mismatch between %s (index %d) and %s " 2001 "(index %d): w_rmatrix[%d][%d] == %hhx but " 2002 "w_rmatrix[%d][%d] == %hhx\n", 2003 fname, w1->w_name, i1, w2->w_name, i2, i1, i2, r1, 2004 i2, i1, r2); 2005 kdb_backtrace(); 2006 printf("Witness disabled.\n"); 2007 witness_watch = -1; 2008 } 2009 return (r1 & rmask); 2010 } 2011 2012 /* 2013 * Checks if @child is a direct child of @parent. 2014 */ 2015 static int 2016 isitmychild(struct witness *parent, struct witness *child) 2017 { 2018 2019 return (_isitmyx(parent, child, WITNESS_PARENT, __func__)); 2020 } 2021 2022 /* 2023 * Checks if @descendant is a direct or inderect descendant of @ancestor. 2024 */ 2025 static int 2026 isitmydescendant(struct witness *ancestor, struct witness *descendant) 2027 { 2028 2029 return (_isitmyx(ancestor, descendant, WITNESS_ANCESTOR_MASK, 2030 __func__)); 2031 } 2032 2033 #ifdef BLESSING 2034 static int 2035 blessed(struct witness *w1, struct witness *w2) 2036 { 2037 int i; 2038 struct witness_blessed *b; 2039 2040 for (i = 0; i < blessed_count; i++) { 2041 b = &blessed_list[i]; 2042 if (strcmp(w1->w_name, b->b_lock1) == 0) { 2043 if (strcmp(w2->w_name, b->b_lock2) == 0) 2044 return (1); 2045 continue; 2046 } 2047 if (strcmp(w1->w_name, b->b_lock2) == 0) 2048 if (strcmp(w2->w_name, b->b_lock1) == 0) 2049 return (1); 2050 } 2051 return (0); 2052 } 2053 #endif 2054 2055 static struct witness * 2056 witness_get(void) 2057 { 2058 struct witness *w; 2059 int index; 2060 2061 if (witness_cold == 0) 2062 mtx_assert(&w_mtx, MA_OWNED); 2063 2064 if (witness_watch == -1) { 2065 mtx_unlock_spin(&w_mtx); 2066 return (NULL); 2067 } 2068 if (STAILQ_EMPTY(&w_free)) { 2069 witness_watch = -1; 2070 mtx_unlock_spin(&w_mtx); 2071 printf("WITNESS: unable to allocate a new witness object\n"); 2072 return (NULL); 2073 } 2074 w = STAILQ_FIRST(&w_free); 2075 STAILQ_REMOVE_HEAD(&w_free, w_list); 2076 w_free_cnt--; 2077 index = w->w_index; 2078 MPASS(index > 0 && index == w_max_used_index+1 && 2079 index < WITNESS_COUNT); 2080 bzero(w, sizeof(*w)); 2081 w->w_index = index; 2082 if (index > w_max_used_index) 2083 w_max_used_index = index; 2084 return (w); 2085 } 2086 2087 static void 2088 witness_free(struct witness *w) 2089 { 2090 2091 STAILQ_INSERT_HEAD(&w_free, w, w_list); 2092 w_free_cnt++; 2093 } 2094 2095 static struct lock_list_entry * 2096 witness_lock_list_get(void) 2097 { 2098 struct lock_list_entry *lle; 2099 2100 if (witness_watch == -1) 2101 return (NULL); 2102 mtx_lock_spin(&w_mtx); 2103 lle = w_lock_list_free; 2104 if (lle == NULL) { 2105 witness_watch = -1; 2106 mtx_unlock_spin(&w_mtx); 2107 printf("%s: witness exhausted\n", __func__); 2108 return (NULL); 2109 } 2110 w_lock_list_free = lle->ll_next; 2111 mtx_unlock_spin(&w_mtx); 2112 bzero(lle, sizeof(*lle)); 2113 return (lle); 2114 } 2115 2116 static void 2117 witness_lock_list_free(struct lock_list_entry *lle) 2118 { 2119 2120 mtx_lock_spin(&w_mtx); 2121 lle->ll_next = w_lock_list_free; 2122 w_lock_list_free = lle; 2123 mtx_unlock_spin(&w_mtx); 2124 } 2125 2126 static struct lock_instance * 2127 find_instance(struct lock_list_entry *list, const struct lock_object *lock) 2128 { 2129 struct lock_list_entry *lle; 2130 struct lock_instance *instance; 2131 int i; 2132 2133 for (lle = list; lle != NULL; lle = lle->ll_next) 2134 for (i = lle->ll_count - 1; i >= 0; i--) { 2135 instance = &lle->ll_children[i]; 2136 if (instance->li_lock == lock) 2137 return (instance); 2138 } 2139 return (NULL); 2140 } 2141 2142 static void 2143 witness_list_lock(struct lock_instance *instance, 2144 int (*prnt)(const char *fmt, ...)) 2145 { 2146 struct lock_object *lock; 2147 2148 lock = instance->li_lock; 2149 prnt("%s %s %s", (instance->li_flags & LI_EXCLUSIVE) != 0 ? 2150 "exclusive" : "shared", LOCK_CLASS(lock)->lc_name, lock->lo_name); 2151 if (lock->lo_witness->w_name != lock->lo_name) 2152 prnt(" (%s)", lock->lo_witness->w_name); 2153 prnt(" r = %d (%p) locked @ %s:%d\n", 2154 instance->li_flags & LI_RECURSEMASK, lock, 2155 fixup_filename(instance->li_file), instance->li_line); 2156 } 2157 2158 #ifdef DDB 2159 static int 2160 witness_thread_has_locks(struct thread *td) 2161 { 2162 2163 if (td->td_sleeplocks == NULL) 2164 return (0); 2165 return (td->td_sleeplocks->ll_count != 0); 2166 } 2167 2168 static int 2169 witness_proc_has_locks(struct proc *p) 2170 { 2171 struct thread *td; 2172 2173 FOREACH_THREAD_IN_PROC(p, td) { 2174 if (witness_thread_has_locks(td)) 2175 return (1); 2176 } 2177 return (0); 2178 } 2179 #endif 2180 2181 int 2182 witness_list_locks(struct lock_list_entry **lock_list, 2183 int (*prnt)(const char *fmt, ...)) 2184 { 2185 struct lock_list_entry *lle; 2186 int i, nheld; 2187 2188 nheld = 0; 2189 for (lle = *lock_list; lle != NULL; lle = lle->ll_next) 2190 for (i = lle->ll_count - 1; i >= 0; i--) { 2191 witness_list_lock(&lle->ll_children[i], prnt); 2192 nheld++; 2193 } 2194 return (nheld); 2195 } 2196 2197 /* 2198 * This is a bit risky at best. We call this function when we have timed 2199 * out acquiring a spin lock, and we assume that the other CPU is stuck 2200 * with this lock held. So, we go groveling around in the other CPU's 2201 * per-cpu data to try to find the lock instance for this spin lock to 2202 * see when it was last acquired. 2203 */ 2204 void 2205 witness_display_spinlock(struct lock_object *lock, struct thread *owner, 2206 int (*prnt)(const char *fmt, ...)) 2207 { 2208 struct lock_instance *instance; 2209 struct pcpu *pc; 2210 2211 if (owner->td_critnest == 0 || owner->td_oncpu == NOCPU) 2212 return; 2213 pc = pcpu_find(owner->td_oncpu); 2214 instance = find_instance(pc->pc_spinlocks, lock); 2215 if (instance != NULL) 2216 witness_list_lock(instance, prnt); 2217 } 2218 2219 void 2220 witness_save(struct lock_object *lock, const char **filep, int *linep) 2221 { 2222 struct lock_list_entry *lock_list; 2223 struct lock_instance *instance; 2224 struct lock_class *class; 2225 2226 /* 2227 * This function is used independently in locking code to deal with 2228 * Giant, SCHEDULER_STOPPED() check can be removed here after Giant 2229 * is gone. 2230 */ 2231 if (SCHEDULER_STOPPED()) 2232 return; 2233 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); 2234 if (lock->lo_witness == NULL || witness_watch == -1 || panicstr != NULL) 2235 return; 2236 class = LOCK_CLASS(lock); 2237 if (class->lc_flags & LC_SLEEPLOCK) 2238 lock_list = curthread->td_sleeplocks; 2239 else { 2240 if (witness_skipspin) 2241 return; 2242 lock_list = PCPU_GET(spinlocks); 2243 } 2244 instance = find_instance(lock_list, lock); 2245 if (instance == NULL) { 2246 kassert_panic("%s: lock (%s) %s not locked", __func__, 2247 class->lc_name, lock->lo_name); 2248 return; 2249 } 2250 *filep = instance->li_file; 2251 *linep = instance->li_line; 2252 } 2253 2254 void 2255 witness_restore(struct lock_object *lock, const char *file, int line) 2256 { 2257 struct lock_list_entry *lock_list; 2258 struct lock_instance *instance; 2259 struct lock_class *class; 2260 2261 /* 2262 * This function is used independently in locking code to deal with 2263 * Giant, SCHEDULER_STOPPED() check can be removed here after Giant 2264 * is gone. 2265 */ 2266 if (SCHEDULER_STOPPED()) 2267 return; 2268 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); 2269 if (lock->lo_witness == NULL || witness_watch == -1 || panicstr != NULL) 2270 return; 2271 class = LOCK_CLASS(lock); 2272 if (class->lc_flags & LC_SLEEPLOCK) 2273 lock_list = curthread->td_sleeplocks; 2274 else { 2275 if (witness_skipspin) 2276 return; 2277 lock_list = PCPU_GET(spinlocks); 2278 } 2279 instance = find_instance(lock_list, lock); 2280 if (instance == NULL) 2281 kassert_panic("%s: lock (%s) %s not locked", __func__, 2282 class->lc_name, lock->lo_name); 2283 lock->lo_witness->w_file = file; 2284 lock->lo_witness->w_line = line; 2285 if (instance == NULL) 2286 return; 2287 instance->li_file = file; 2288 instance->li_line = line; 2289 } 2290 2291 void 2292 witness_assert(const struct lock_object *lock, int flags, const char *file, 2293 int line) 2294 { 2295 #ifdef INVARIANT_SUPPORT 2296 struct lock_instance *instance; 2297 struct lock_class *class; 2298 2299 if (lock->lo_witness == NULL || witness_watch < 1 || panicstr != NULL) 2300 return; 2301 class = LOCK_CLASS(lock); 2302 if ((class->lc_flags & LC_SLEEPLOCK) != 0) 2303 instance = find_instance(curthread->td_sleeplocks, lock); 2304 else if ((class->lc_flags & LC_SPINLOCK) != 0) 2305 instance = find_instance(PCPU_GET(spinlocks), lock); 2306 else { 2307 kassert_panic("Lock (%s) %s is not sleep or spin!", 2308 class->lc_name, lock->lo_name); 2309 return; 2310 } 2311 switch (flags) { 2312 case LA_UNLOCKED: 2313 if (instance != NULL) 2314 kassert_panic("Lock (%s) %s locked @ %s:%d.", 2315 class->lc_name, lock->lo_name, 2316 fixup_filename(file), line); 2317 break; 2318 case LA_LOCKED: 2319 case LA_LOCKED | LA_RECURSED: 2320 case LA_LOCKED | LA_NOTRECURSED: 2321 case LA_SLOCKED: 2322 case LA_SLOCKED | LA_RECURSED: 2323 case LA_SLOCKED | LA_NOTRECURSED: 2324 case LA_XLOCKED: 2325 case LA_XLOCKED | LA_RECURSED: 2326 case LA_XLOCKED | LA_NOTRECURSED: 2327 if (instance == NULL) { 2328 kassert_panic("Lock (%s) %s not locked @ %s:%d.", 2329 class->lc_name, lock->lo_name, 2330 fixup_filename(file), line); 2331 break; 2332 } 2333 if ((flags & LA_XLOCKED) != 0 && 2334 (instance->li_flags & LI_EXCLUSIVE) == 0) 2335 kassert_panic( 2336 "Lock (%s) %s not exclusively locked @ %s:%d.", 2337 class->lc_name, lock->lo_name, 2338 fixup_filename(file), line); 2339 if ((flags & LA_SLOCKED) != 0 && 2340 (instance->li_flags & LI_EXCLUSIVE) != 0) 2341 kassert_panic( 2342 "Lock (%s) %s exclusively locked @ %s:%d.", 2343 class->lc_name, lock->lo_name, 2344 fixup_filename(file), line); 2345 if ((flags & LA_RECURSED) != 0 && 2346 (instance->li_flags & LI_RECURSEMASK) == 0) 2347 kassert_panic("Lock (%s) %s not recursed @ %s:%d.", 2348 class->lc_name, lock->lo_name, 2349 fixup_filename(file), line); 2350 if ((flags & LA_NOTRECURSED) != 0 && 2351 (instance->li_flags & LI_RECURSEMASK) != 0) 2352 kassert_panic("Lock (%s) %s recursed @ %s:%d.", 2353 class->lc_name, lock->lo_name, 2354 fixup_filename(file), line); 2355 break; 2356 default: 2357 kassert_panic("Invalid lock assertion at %s:%d.", 2358 fixup_filename(file), line); 2359 2360 } 2361 #endif /* INVARIANT_SUPPORT */ 2362 } 2363 2364 static void 2365 witness_setflag(struct lock_object *lock, int flag, int set) 2366 { 2367 struct lock_list_entry *lock_list; 2368 struct lock_instance *instance; 2369 struct lock_class *class; 2370 2371 if (lock->lo_witness == NULL || witness_watch == -1 || panicstr != NULL) 2372 return; 2373 class = LOCK_CLASS(lock); 2374 if (class->lc_flags & LC_SLEEPLOCK) 2375 lock_list = curthread->td_sleeplocks; 2376 else { 2377 if (witness_skipspin) 2378 return; 2379 lock_list = PCPU_GET(spinlocks); 2380 } 2381 instance = find_instance(lock_list, lock); 2382 if (instance == NULL) { 2383 kassert_panic("%s: lock (%s) %s not locked", __func__, 2384 class->lc_name, lock->lo_name); 2385 return; 2386 } 2387 2388 if (set) 2389 instance->li_flags |= flag; 2390 else 2391 instance->li_flags &= ~flag; 2392 } 2393 2394 void 2395 witness_norelease(struct lock_object *lock) 2396 { 2397 2398 witness_setflag(lock, LI_NORELEASE, 1); 2399 } 2400 2401 void 2402 witness_releaseok(struct lock_object *lock) 2403 { 2404 2405 witness_setflag(lock, LI_NORELEASE, 0); 2406 } 2407 2408 #ifdef DDB 2409 static void 2410 witness_ddb_list(struct thread *td) 2411 { 2412 2413 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); 2414 KASSERT(kdb_active, ("%s: not in the debugger", __func__)); 2415 2416 if (witness_watch < 1) 2417 return; 2418 2419 witness_list_locks(&td->td_sleeplocks, db_printf); 2420 2421 /* 2422 * We only handle spinlocks if td == curthread. This is somewhat broken 2423 * if td is currently executing on some other CPU and holds spin locks 2424 * as we won't display those locks. If we had a MI way of getting 2425 * the per-cpu data for a given cpu then we could use 2426 * td->td_oncpu to get the list of spinlocks for this thread 2427 * and "fix" this. 2428 * 2429 * That still wouldn't really fix this unless we locked the scheduler 2430 * lock or stopped the other CPU to make sure it wasn't changing the 2431 * list out from under us. It is probably best to just not try to 2432 * handle threads on other CPU's for now. 2433 */ 2434 if (td == curthread && PCPU_GET(spinlocks) != NULL) 2435 witness_list_locks(PCPU_PTR(spinlocks), db_printf); 2436 } 2437 2438 DB_SHOW_COMMAND(locks, db_witness_list) 2439 { 2440 struct thread *td; 2441 2442 if (have_addr) 2443 td = db_lookup_thread(addr, TRUE); 2444 else 2445 td = kdb_thread; 2446 witness_ddb_list(td); 2447 } 2448 2449 DB_SHOW_ALL_COMMAND(locks, db_witness_list_all) 2450 { 2451 struct thread *td; 2452 struct proc *p; 2453 2454 /* 2455 * It would be nice to list only threads and processes that actually 2456 * held sleep locks, but that information is currently not exported 2457 * by WITNESS. 2458 */ 2459 FOREACH_PROC_IN_SYSTEM(p) { 2460 if (!witness_proc_has_locks(p)) 2461 continue; 2462 FOREACH_THREAD_IN_PROC(p, td) { 2463 if (!witness_thread_has_locks(td)) 2464 continue; 2465 db_printf("Process %d (%s) thread %p (%d)\n", p->p_pid, 2466 p->p_comm, td, td->td_tid); 2467 witness_ddb_list(td); 2468 if (db_pager_quit) 2469 return; 2470 } 2471 } 2472 } 2473 DB_SHOW_ALIAS(alllocks, db_witness_list_all) 2474 2475 DB_SHOW_COMMAND(witness, db_witness_display) 2476 { 2477 2478 witness_ddb_display(db_printf); 2479 } 2480 #endif 2481 2482 static int 2483 sysctl_debug_witness_badstacks(SYSCTL_HANDLER_ARGS) 2484 { 2485 struct witness_lock_order_data *data1, *data2, *tmp_data1, *tmp_data2; 2486 struct witness *tmp_w1, *tmp_w2, *w1, *w2; 2487 struct sbuf *sb; 2488 u_int w_rmatrix1, w_rmatrix2; 2489 int error, generation, i, j; 2490 2491 tmp_data1 = NULL; 2492 tmp_data2 = NULL; 2493 tmp_w1 = NULL; 2494 tmp_w2 = NULL; 2495 if (witness_watch < 1) { 2496 error = SYSCTL_OUT(req, w_notrunning, sizeof(w_notrunning)); 2497 return (error); 2498 } 2499 if (witness_cold) { 2500 error = SYSCTL_OUT(req, w_stillcold, sizeof(w_stillcold)); 2501 return (error); 2502 } 2503 error = 0; 2504 sb = sbuf_new(NULL, NULL, BADSTACK_SBUF_SIZE, SBUF_AUTOEXTEND); 2505 if (sb == NULL) 2506 return (ENOMEM); 2507 2508 /* Allocate and init temporary storage space. */ 2509 tmp_w1 = malloc(sizeof(struct witness), M_TEMP, M_WAITOK | M_ZERO); 2510 tmp_w2 = malloc(sizeof(struct witness), M_TEMP, M_WAITOK | M_ZERO); 2511 tmp_data1 = malloc(sizeof(struct witness_lock_order_data), M_TEMP, 2512 M_WAITOK | M_ZERO); 2513 tmp_data2 = malloc(sizeof(struct witness_lock_order_data), M_TEMP, 2514 M_WAITOK | M_ZERO); 2515 stack_zero(&tmp_data1->wlod_stack); 2516 stack_zero(&tmp_data2->wlod_stack); 2517 2518 restart: 2519 mtx_lock_spin(&w_mtx); 2520 generation = w_generation; 2521 mtx_unlock_spin(&w_mtx); 2522 sbuf_printf(sb, "Number of known direct relationships is %d\n", 2523 w_lohash.wloh_count); 2524 for (i = 1; i < w_max_used_index; i++) { 2525 mtx_lock_spin(&w_mtx); 2526 if (generation != w_generation) { 2527 mtx_unlock_spin(&w_mtx); 2528 2529 /* The graph has changed, try again. */ 2530 req->oldidx = 0; 2531 sbuf_clear(sb); 2532 goto restart; 2533 } 2534 2535 w1 = &w_data[i]; 2536 if (w1->w_reversed == 0) { 2537 mtx_unlock_spin(&w_mtx); 2538 continue; 2539 } 2540 2541 /* Copy w1 locally so we can release the spin lock. */ 2542 *tmp_w1 = *w1; 2543 mtx_unlock_spin(&w_mtx); 2544 2545 if (tmp_w1->w_reversed == 0) 2546 continue; 2547 for (j = 1; j < w_max_used_index; j++) { 2548 if ((w_rmatrix[i][j] & WITNESS_REVERSAL) == 0 || i > j) 2549 continue; 2550 2551 mtx_lock_spin(&w_mtx); 2552 if (generation != w_generation) { 2553 mtx_unlock_spin(&w_mtx); 2554 2555 /* The graph has changed, try again. */ 2556 req->oldidx = 0; 2557 sbuf_clear(sb); 2558 goto restart; 2559 } 2560 2561 w2 = &w_data[j]; 2562 data1 = witness_lock_order_get(w1, w2); 2563 data2 = witness_lock_order_get(w2, w1); 2564 2565 /* 2566 * Copy information locally so we can release the 2567 * spin lock. 2568 */ 2569 *tmp_w2 = *w2; 2570 w_rmatrix1 = (unsigned int)w_rmatrix[i][j]; 2571 w_rmatrix2 = (unsigned int)w_rmatrix[j][i]; 2572 2573 if (data1) { 2574 stack_zero(&tmp_data1->wlod_stack); 2575 stack_copy(&data1->wlod_stack, 2576 &tmp_data1->wlod_stack); 2577 } 2578 if (data2 && data2 != data1) { 2579 stack_zero(&tmp_data2->wlod_stack); 2580 stack_copy(&data2->wlod_stack, 2581 &tmp_data2->wlod_stack); 2582 } 2583 mtx_unlock_spin(&w_mtx); 2584 2585 sbuf_printf(sb, 2586 "\nLock order reversal between \"%s\"(%s) and \"%s\"(%s)!\n", 2587 tmp_w1->w_name, tmp_w1->w_class->lc_name, 2588 tmp_w2->w_name, tmp_w2->w_class->lc_name); 2589 #if 0 2590 sbuf_printf(sb, 2591 "w_rmatrix[%s][%s] == %x, w_rmatrix[%s][%s] == %x\n", 2592 tmp_w1->name, tmp_w2->w_name, w_rmatrix1, 2593 tmp_w2->name, tmp_w1->w_name, w_rmatrix2); 2594 #endif 2595 if (data1) { 2596 sbuf_printf(sb, 2597 "Lock order \"%s\"(%s) -> \"%s\"(%s) first seen at:\n", 2598 tmp_w1->w_name, tmp_w1->w_class->lc_name, 2599 tmp_w2->w_name, tmp_w2->w_class->lc_name); 2600 stack_sbuf_print(sb, &tmp_data1->wlod_stack); 2601 sbuf_printf(sb, "\n"); 2602 } 2603 if (data2 && data2 != data1) { 2604 sbuf_printf(sb, 2605 "Lock order \"%s\"(%s) -> \"%s\"(%s) first seen at:\n", 2606 tmp_w2->w_name, tmp_w2->w_class->lc_name, 2607 tmp_w1->w_name, tmp_w1->w_class->lc_name); 2608 stack_sbuf_print(sb, &tmp_data2->wlod_stack); 2609 sbuf_printf(sb, "\n"); 2610 } 2611 } 2612 } 2613 mtx_lock_spin(&w_mtx); 2614 if (generation != w_generation) { 2615 mtx_unlock_spin(&w_mtx); 2616 2617 /* 2618 * The graph changed while we were printing stack data, 2619 * try again. 2620 */ 2621 req->oldidx = 0; 2622 sbuf_clear(sb); 2623 goto restart; 2624 } 2625 mtx_unlock_spin(&w_mtx); 2626 2627 /* Free temporary storage space. */ 2628 free(tmp_data1, M_TEMP); 2629 free(tmp_data2, M_TEMP); 2630 free(tmp_w1, M_TEMP); 2631 free(tmp_w2, M_TEMP); 2632 2633 sbuf_finish(sb); 2634 error = SYSCTL_OUT(req, sbuf_data(sb), sbuf_len(sb) + 1); 2635 sbuf_delete(sb); 2636 2637 return (error); 2638 } 2639 2640 static int 2641 sysctl_debug_witness_fullgraph(SYSCTL_HANDLER_ARGS) 2642 { 2643 struct witness *w; 2644 struct sbuf *sb; 2645 int error; 2646 2647 if (witness_watch < 1) { 2648 error = SYSCTL_OUT(req, w_notrunning, sizeof(w_notrunning)); 2649 return (error); 2650 } 2651 if (witness_cold) { 2652 error = SYSCTL_OUT(req, w_stillcold, sizeof(w_stillcold)); 2653 return (error); 2654 } 2655 error = 0; 2656 2657 error = sysctl_wire_old_buffer(req, 0); 2658 if (error != 0) 2659 return (error); 2660 sb = sbuf_new_for_sysctl(NULL, NULL, FULLGRAPH_SBUF_SIZE, req); 2661 if (sb == NULL) 2662 return (ENOMEM); 2663 sbuf_printf(sb, "\n"); 2664 2665 mtx_lock_spin(&w_mtx); 2666 STAILQ_FOREACH(w, &w_all, w_list) 2667 w->w_displayed = 0; 2668 STAILQ_FOREACH(w, &w_all, w_list) 2669 witness_add_fullgraph(sb, w); 2670 mtx_unlock_spin(&w_mtx); 2671 2672 /* 2673 * Close the sbuf and return to userland. 2674 */ 2675 error = sbuf_finish(sb); 2676 sbuf_delete(sb); 2677 2678 return (error); 2679 } 2680 2681 static int 2682 sysctl_debug_witness_watch(SYSCTL_HANDLER_ARGS) 2683 { 2684 int error, value; 2685 2686 value = witness_watch; 2687 error = sysctl_handle_int(oidp, &value, 0, req); 2688 if (error != 0 || req->newptr == NULL) 2689 return (error); 2690 if (value > 1 || value < -1 || 2691 (witness_watch == -1 && value != witness_watch)) 2692 return (EINVAL); 2693 witness_watch = value; 2694 return (0); 2695 } 2696 2697 static void 2698 witness_add_fullgraph(struct sbuf *sb, struct witness *w) 2699 { 2700 int i; 2701 2702 if (w->w_displayed != 0 || (w->w_file == NULL && w->w_line == 0)) 2703 return; 2704 w->w_displayed = 1; 2705 2706 WITNESS_INDEX_ASSERT(w->w_index); 2707 for (i = 1; i <= w_max_used_index; i++) { 2708 if (w_rmatrix[w->w_index][i] & WITNESS_PARENT) { 2709 sbuf_printf(sb, "\"%s\",\"%s\"\n", w->w_name, 2710 w_data[i].w_name); 2711 witness_add_fullgraph(sb, &w_data[i]); 2712 } 2713 } 2714 } 2715 2716 /* 2717 * A simple hash function. Takes a key pointer and a key size. If size == 0, 2718 * interprets the key as a string and reads until the null 2719 * terminator. Otherwise, reads the first size bytes. Returns an unsigned 32-bit 2720 * hash value computed from the key. 2721 */ 2722 static uint32_t 2723 witness_hash_djb2(const uint8_t *key, uint32_t size) 2724 { 2725 unsigned int hash = 5381; 2726 int i; 2727 2728 /* hash = hash * 33 + key[i] */ 2729 if (size) 2730 for (i = 0; i < size; i++) 2731 hash = ((hash << 5) + hash) + (unsigned int)key[i]; 2732 else 2733 for (i = 0; key[i] != 0; i++) 2734 hash = ((hash << 5) + hash) + (unsigned int)key[i]; 2735 2736 return (hash); 2737 } 2738 2739 2740 /* 2741 * Initializes the two witness hash tables. Called exactly once from 2742 * witness_initialize(). 2743 */ 2744 static void 2745 witness_init_hash_tables(void) 2746 { 2747 int i; 2748 2749 MPASS(witness_cold); 2750 2751 /* Initialize the hash tables. */ 2752 for (i = 0; i < WITNESS_HASH_SIZE; i++) 2753 w_hash.wh_array[i] = NULL; 2754 2755 w_hash.wh_size = WITNESS_HASH_SIZE; 2756 w_hash.wh_count = 0; 2757 2758 /* Initialize the lock order data hash. */ 2759 w_lofree = NULL; 2760 for (i = 0; i < WITNESS_LO_DATA_COUNT; i++) { 2761 memset(&w_lodata[i], 0, sizeof(w_lodata[i])); 2762 w_lodata[i].wlod_next = w_lofree; 2763 w_lofree = &w_lodata[i]; 2764 } 2765 w_lohash.wloh_size = WITNESS_LO_HASH_SIZE; 2766 w_lohash.wloh_count = 0; 2767 for (i = 0; i < WITNESS_LO_HASH_SIZE; i++) 2768 w_lohash.wloh_array[i] = NULL; 2769 } 2770 2771 static struct witness * 2772 witness_hash_get(const char *key) 2773 { 2774 struct witness *w; 2775 uint32_t hash; 2776 2777 MPASS(key != NULL); 2778 if (witness_cold == 0) 2779 mtx_assert(&w_mtx, MA_OWNED); 2780 hash = witness_hash_djb2(key, 0) % w_hash.wh_size; 2781 w = w_hash.wh_array[hash]; 2782 while (w != NULL) { 2783 if (strcmp(w->w_name, key) == 0) 2784 goto out; 2785 w = w->w_hash_next; 2786 } 2787 2788 out: 2789 return (w); 2790 } 2791 2792 static void 2793 witness_hash_put(struct witness *w) 2794 { 2795 uint32_t hash; 2796 2797 MPASS(w != NULL); 2798 MPASS(w->w_name != NULL); 2799 if (witness_cold == 0) 2800 mtx_assert(&w_mtx, MA_OWNED); 2801 KASSERT(witness_hash_get(w->w_name) == NULL, 2802 ("%s: trying to add a hash entry that already exists!", __func__)); 2803 KASSERT(w->w_hash_next == NULL, 2804 ("%s: w->w_hash_next != NULL", __func__)); 2805 2806 hash = witness_hash_djb2(w->w_name, 0) % w_hash.wh_size; 2807 w->w_hash_next = w_hash.wh_array[hash]; 2808 w_hash.wh_array[hash] = w; 2809 w_hash.wh_count++; 2810 } 2811 2812 2813 static struct witness_lock_order_data * 2814 witness_lock_order_get(struct witness *parent, struct witness *child) 2815 { 2816 struct witness_lock_order_data *data = NULL; 2817 struct witness_lock_order_key key; 2818 unsigned int hash; 2819 2820 MPASS(parent != NULL && child != NULL); 2821 key.from = parent->w_index; 2822 key.to = child->w_index; 2823 WITNESS_INDEX_ASSERT(key.from); 2824 WITNESS_INDEX_ASSERT(key.to); 2825 if ((w_rmatrix[parent->w_index][child->w_index] 2826 & WITNESS_LOCK_ORDER_KNOWN) == 0) 2827 goto out; 2828 2829 hash = witness_hash_djb2((const char*)&key, 2830 sizeof(key)) % w_lohash.wloh_size; 2831 data = w_lohash.wloh_array[hash]; 2832 while (data != NULL) { 2833 if (witness_lock_order_key_equal(&data->wlod_key, &key)) 2834 break; 2835 data = data->wlod_next; 2836 } 2837 2838 out: 2839 return (data); 2840 } 2841 2842 /* 2843 * Verify that parent and child have a known relationship, are not the same, 2844 * and child is actually a child of parent. This is done without w_mtx 2845 * to avoid contention in the common case. 2846 */ 2847 static int 2848 witness_lock_order_check(struct witness *parent, struct witness *child) 2849 { 2850 2851 if (parent != child && 2852 w_rmatrix[parent->w_index][child->w_index] 2853 & WITNESS_LOCK_ORDER_KNOWN && 2854 isitmychild(parent, child)) 2855 return (1); 2856 2857 return (0); 2858 } 2859 2860 static int 2861 witness_lock_order_add(struct witness *parent, struct witness *child) 2862 { 2863 struct witness_lock_order_data *data = NULL; 2864 struct witness_lock_order_key key; 2865 unsigned int hash; 2866 2867 MPASS(parent != NULL && child != NULL); 2868 key.from = parent->w_index; 2869 key.to = child->w_index; 2870 WITNESS_INDEX_ASSERT(key.from); 2871 WITNESS_INDEX_ASSERT(key.to); 2872 if (w_rmatrix[parent->w_index][child->w_index] 2873 & WITNESS_LOCK_ORDER_KNOWN) 2874 return (1); 2875 2876 hash = witness_hash_djb2((const char*)&key, 2877 sizeof(key)) % w_lohash.wloh_size; 2878 w_rmatrix[parent->w_index][child->w_index] |= WITNESS_LOCK_ORDER_KNOWN; 2879 data = w_lofree; 2880 if (data == NULL) 2881 return (0); 2882 w_lofree = data->wlod_next; 2883 data->wlod_next = w_lohash.wloh_array[hash]; 2884 data->wlod_key = key; 2885 w_lohash.wloh_array[hash] = data; 2886 w_lohash.wloh_count++; 2887 stack_zero(&data->wlod_stack); 2888 stack_save(&data->wlod_stack); 2889 return (1); 2890 } 2891 2892 /* Call this whenver the structure of the witness graph changes. */ 2893 static void 2894 witness_increment_graph_generation(void) 2895 { 2896 2897 if (witness_cold == 0) 2898 mtx_assert(&w_mtx, MA_OWNED); 2899 w_generation++; 2900 } 2901 2902 #ifdef KDB 2903 static void 2904 _witness_debugger(int cond, const char *msg) 2905 { 2906 2907 if (witness_trace && cond) 2908 kdb_backtrace(); 2909 if (witness_kdb && cond) 2910 kdb_enter(KDB_WHY_WITNESS, msg); 2911 } 2912 #endif 2913