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 768 139 140 /* 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( 1142 "interlock (%s) %s not locked while locking" 1143 " %s @ %s:%d", 1144 iclass->lc_name, interlock->lo_name, 1145 flags & LOP_EXCLUSIVE ? "exclusive" : "shared", 1146 fixup_filename(file), line); 1147 else if ((lock1->li_flags & LI_RECURSEMASK) != 0) 1148 kassert_panic( 1149 "interlock (%s) %s recursed while locking %s" 1150 " @ %s:%d", 1151 iclass->lc_name, interlock->lo_name, 1152 flags & LOP_EXCLUSIVE ? "exclusive" : "shared", 1153 fixup_filename(file), line); 1154 } 1155 1156 /* 1157 * Find the previously acquired lock, but ignore interlocks. 1158 */ 1159 plock = &lock_list->ll_children[lock_list->ll_count - 1]; 1160 if (interlock != NULL && plock->li_lock == interlock) { 1161 if (lock_list->ll_count > 1) 1162 plock = 1163 &lock_list->ll_children[lock_list->ll_count - 2]; 1164 else { 1165 lle = lock_list->ll_next; 1166 1167 /* 1168 * The interlock is the only lock we hold, so 1169 * simply return. 1170 */ 1171 if (lle == NULL) 1172 return; 1173 plock = &lle->ll_children[lle->ll_count - 1]; 1174 } 1175 } 1176 1177 /* 1178 * Try to perform most checks without a lock. If this succeeds we 1179 * can skip acquiring the lock and return success. 1180 */ 1181 w1 = plock->li_lock->lo_witness; 1182 if (witness_lock_order_check(w1, w)) 1183 return; 1184 1185 /* 1186 * Check for duplicate locks of the same type. Note that we only 1187 * have to check for this on the last lock we just acquired. Any 1188 * other cases will be caught as lock order violations. 1189 */ 1190 mtx_lock_spin(&w_mtx); 1191 witness_lock_order_add(w1, w); 1192 if (w1 == w) { 1193 i = w->w_index; 1194 if (!(lock->lo_flags & LO_DUPOK) && !(flags & LOP_DUPOK) && 1195 !(w_rmatrix[i][i] & WITNESS_REVERSAL)) { 1196 w_rmatrix[i][i] |= WITNESS_REVERSAL; 1197 w->w_reversed = 1; 1198 mtx_unlock_spin(&w_mtx); 1199 printf( 1200 "acquiring duplicate lock of same type: \"%s\"\n", 1201 w->w_name); 1202 printf(" 1st %s @ %s:%d\n", plock->li_lock->lo_name, 1203 fixup_filename(plock->li_file), plock->li_line); 1204 printf(" 2nd %s @ %s:%d\n", lock->lo_name, 1205 fixup_filename(file), line); 1206 witness_debugger(1); 1207 } else 1208 mtx_unlock_spin(&w_mtx); 1209 return; 1210 } 1211 mtx_assert(&w_mtx, MA_OWNED); 1212 1213 /* 1214 * If we know that the lock we are acquiring comes after 1215 * the lock we most recently acquired in the lock order tree, 1216 * then there is no need for any further checks. 1217 */ 1218 if (isitmychild(w1, w)) 1219 goto out; 1220 1221 for (j = 0, lle = lock_list; lle != NULL; lle = lle->ll_next) { 1222 for (i = lle->ll_count - 1; i >= 0; i--, j++) { 1223 1224 MPASS(j < WITNESS_COUNT); 1225 lock1 = &lle->ll_children[i]; 1226 1227 /* 1228 * Ignore the interlock. 1229 */ 1230 if (interlock == lock1->li_lock) 1231 continue; 1232 1233 /* 1234 * If this lock doesn't undergo witness checking, 1235 * then skip it. 1236 */ 1237 w1 = lock1->li_lock->lo_witness; 1238 if (w1 == NULL) { 1239 KASSERT((lock1->li_lock->lo_flags & LO_WITNESS) == 0, 1240 ("lock missing witness structure")); 1241 continue; 1242 } 1243 1244 /* 1245 * If we are locking Giant and this is a sleepable 1246 * lock, then skip it. 1247 */ 1248 if ((lock1->li_lock->lo_flags & LO_SLEEPABLE) != 0 && 1249 lock == &Giant.lock_object) 1250 continue; 1251 1252 /* 1253 * If we are locking a sleepable lock and this lock 1254 * is Giant, then skip it. 1255 */ 1256 if ((lock->lo_flags & LO_SLEEPABLE) != 0 && 1257 lock1->li_lock == &Giant.lock_object) 1258 continue; 1259 1260 /* 1261 * If we are locking a sleepable lock and this lock 1262 * isn't sleepable, we want to treat it as a lock 1263 * order violation to enfore a general lock order of 1264 * sleepable locks before non-sleepable locks. 1265 */ 1266 if (((lock->lo_flags & LO_SLEEPABLE) != 0 && 1267 (lock1->li_lock->lo_flags & LO_SLEEPABLE) == 0)) 1268 goto reversal; 1269 1270 /* 1271 * If we are locking Giant and this is a non-sleepable 1272 * lock, then treat it as a reversal. 1273 */ 1274 if ((lock1->li_lock->lo_flags & LO_SLEEPABLE) == 0 && 1275 lock == &Giant.lock_object) 1276 goto reversal; 1277 1278 /* 1279 * Check the lock order hierarchy for a reveresal. 1280 */ 1281 if (!isitmydescendant(w, w1)) 1282 continue; 1283 reversal: 1284 1285 /* 1286 * We have a lock order violation, check to see if it 1287 * is allowed or has already been yelled about. 1288 */ 1289 #ifdef BLESSING 1290 1291 /* 1292 * If the lock order is blessed, just bail. We don't 1293 * look for other lock order violations though, which 1294 * may be a bug. 1295 */ 1296 if (blessed(w, w1)) 1297 goto out; 1298 #endif 1299 1300 /* Bail if this violation is known */ 1301 if (w_rmatrix[w1->w_index][w->w_index] & WITNESS_REVERSAL) 1302 goto out; 1303 1304 /* Record this as a violation */ 1305 w_rmatrix[w1->w_index][w->w_index] |= WITNESS_REVERSAL; 1306 w_rmatrix[w->w_index][w1->w_index] |= WITNESS_REVERSAL; 1307 w->w_reversed = w1->w_reversed = 1; 1308 witness_increment_graph_generation(); 1309 mtx_unlock_spin(&w_mtx); 1310 1311 #ifdef WITNESS_NO_VNODE 1312 /* 1313 * There are known LORs between VNODE locks. They are 1314 * not an indication of a bug. VNODE locks are flagged 1315 * as such (LO_IS_VNODE) and we don't yell if the LOR 1316 * is between 2 VNODE locks. 1317 */ 1318 if ((lock->lo_flags & LO_IS_VNODE) != 0 && 1319 (lock1->li_lock->lo_flags & LO_IS_VNODE) != 0) 1320 return; 1321 #endif 1322 1323 /* 1324 * Ok, yell about it. 1325 */ 1326 if (((lock->lo_flags & LO_SLEEPABLE) != 0 && 1327 (lock1->li_lock->lo_flags & LO_SLEEPABLE) == 0)) 1328 printf( 1329 "lock order reversal: (sleepable after non-sleepable)\n"); 1330 else if ((lock1->li_lock->lo_flags & LO_SLEEPABLE) == 0 1331 && lock == &Giant.lock_object) 1332 printf( 1333 "lock order reversal: (Giant after non-sleepable)\n"); 1334 else 1335 printf("lock order reversal:\n"); 1336 1337 /* 1338 * Try to locate an earlier lock with 1339 * witness w in our list. 1340 */ 1341 do { 1342 lock2 = &lle->ll_children[i]; 1343 MPASS(lock2->li_lock != NULL); 1344 if (lock2->li_lock->lo_witness == w) 1345 break; 1346 if (i == 0 && lle->ll_next != NULL) { 1347 lle = lle->ll_next; 1348 i = lle->ll_count - 1; 1349 MPASS(i >= 0 && i < LOCK_NCHILDREN); 1350 } else 1351 i--; 1352 } while (i >= 0); 1353 if (i < 0) { 1354 printf(" 1st %p %s (%s) @ %s:%d\n", 1355 lock1->li_lock, lock1->li_lock->lo_name, 1356 w1->w_name, fixup_filename(lock1->li_file), 1357 lock1->li_line); 1358 printf(" 2nd %p %s (%s) @ %s:%d\n", lock, 1359 lock->lo_name, w->w_name, 1360 fixup_filename(file), line); 1361 } else { 1362 printf(" 1st %p %s (%s) @ %s:%d\n", 1363 lock2->li_lock, lock2->li_lock->lo_name, 1364 lock2->li_lock->lo_witness->w_name, 1365 fixup_filename(lock2->li_file), 1366 lock2->li_line); 1367 printf(" 2nd %p %s (%s) @ %s:%d\n", 1368 lock1->li_lock, lock1->li_lock->lo_name, 1369 w1->w_name, fixup_filename(lock1->li_file), 1370 lock1->li_line); 1371 printf(" 3rd %p %s (%s) @ %s:%d\n", lock, 1372 lock->lo_name, w->w_name, 1373 fixup_filename(file), line); 1374 } 1375 witness_debugger(1); 1376 return; 1377 } 1378 } 1379 1380 /* 1381 * If requested, build a new lock order. However, don't build a new 1382 * relationship between a sleepable lock and Giant if it is in the 1383 * wrong direction. The correct lock order is that sleepable locks 1384 * always come before Giant. 1385 */ 1386 if (flags & LOP_NEWORDER && 1387 !(plock->li_lock == &Giant.lock_object && 1388 (lock->lo_flags & LO_SLEEPABLE) != 0)) { 1389 CTR3(KTR_WITNESS, "%s: adding %s as a child of %s", __func__, 1390 w->w_name, plock->li_lock->lo_witness->w_name); 1391 itismychild(plock->li_lock->lo_witness, w); 1392 } 1393 out: 1394 mtx_unlock_spin(&w_mtx); 1395 } 1396 1397 void 1398 witness_lock(struct lock_object *lock, int flags, const char *file, int line) 1399 { 1400 struct lock_list_entry **lock_list, *lle; 1401 struct lock_instance *instance; 1402 struct witness *w; 1403 struct thread *td; 1404 1405 if (witness_cold || witness_watch == -1 || lock->lo_witness == NULL || 1406 panicstr != NULL) 1407 return; 1408 w = lock->lo_witness; 1409 td = curthread; 1410 1411 /* Determine lock list for this lock. */ 1412 if (LOCK_CLASS(lock)->lc_flags & LC_SLEEPLOCK) 1413 lock_list = &td->td_sleeplocks; 1414 else 1415 lock_list = PCPU_PTR(spinlocks); 1416 1417 /* Check to see if we are recursing on a lock we already own. */ 1418 instance = find_instance(*lock_list, lock); 1419 if (instance != NULL) { 1420 instance->li_flags++; 1421 CTR4(KTR_WITNESS, "%s: pid %d recursed on %s r=%d", __func__, 1422 td->td_proc->p_pid, lock->lo_name, 1423 instance->li_flags & LI_RECURSEMASK); 1424 instance->li_file = file; 1425 instance->li_line = line; 1426 return; 1427 } 1428 1429 /* Update per-witness last file and line acquire. */ 1430 w->w_file = file; 1431 w->w_line = line; 1432 1433 /* Find the next open lock instance in the list and fill it. */ 1434 lle = *lock_list; 1435 if (lle == NULL || lle->ll_count == LOCK_NCHILDREN) { 1436 lle = witness_lock_list_get(); 1437 if (lle == NULL) 1438 return; 1439 lle->ll_next = *lock_list; 1440 CTR3(KTR_WITNESS, "%s: pid %d added lle %p", __func__, 1441 td->td_proc->p_pid, lle); 1442 *lock_list = lle; 1443 } 1444 instance = &lle->ll_children[lle->ll_count++]; 1445 instance->li_lock = lock; 1446 instance->li_line = line; 1447 instance->li_file = file; 1448 if ((flags & LOP_EXCLUSIVE) != 0) 1449 instance->li_flags = LI_EXCLUSIVE; 1450 else 1451 instance->li_flags = 0; 1452 CTR4(KTR_WITNESS, "%s: pid %d added %s as lle[%d]", __func__, 1453 td->td_proc->p_pid, lock->lo_name, lle->ll_count - 1); 1454 } 1455 1456 void 1457 witness_upgrade(struct lock_object *lock, int flags, const char *file, int line) 1458 { 1459 struct lock_instance *instance; 1460 struct lock_class *class; 1461 1462 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); 1463 if (lock->lo_witness == NULL || witness_watch == -1 || panicstr != NULL) 1464 return; 1465 class = LOCK_CLASS(lock); 1466 if (witness_watch) { 1467 if ((lock->lo_flags & LO_UPGRADABLE) == 0) 1468 kassert_panic( 1469 "upgrade of non-upgradable lock (%s) %s @ %s:%d", 1470 class->lc_name, lock->lo_name, 1471 fixup_filename(file), line); 1472 if ((class->lc_flags & LC_SLEEPLOCK) == 0) 1473 kassert_panic( 1474 "upgrade of non-sleep lock (%s) %s @ %s:%d", 1475 class->lc_name, lock->lo_name, 1476 fixup_filename(file), line); 1477 } 1478 instance = find_instance(curthread->td_sleeplocks, lock); 1479 if (instance == NULL) { 1480 kassert_panic("upgrade of unlocked lock (%s) %s @ %s:%d", 1481 class->lc_name, lock->lo_name, 1482 fixup_filename(file), line); 1483 return; 1484 } 1485 if (witness_watch) { 1486 if ((instance->li_flags & LI_EXCLUSIVE) != 0) 1487 kassert_panic( 1488 "upgrade of exclusive lock (%s) %s @ %s:%d", 1489 class->lc_name, lock->lo_name, 1490 fixup_filename(file), line); 1491 if ((instance->li_flags & LI_RECURSEMASK) != 0) 1492 kassert_panic( 1493 "upgrade of recursed lock (%s) %s r=%d @ %s:%d", 1494 class->lc_name, lock->lo_name, 1495 instance->li_flags & LI_RECURSEMASK, 1496 fixup_filename(file), line); 1497 } 1498 instance->li_flags |= LI_EXCLUSIVE; 1499 } 1500 1501 void 1502 witness_downgrade(struct lock_object *lock, int flags, const char *file, 1503 int line) 1504 { 1505 struct lock_instance *instance; 1506 struct lock_class *class; 1507 1508 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); 1509 if (lock->lo_witness == NULL || witness_watch == -1 || panicstr != NULL) 1510 return; 1511 class = LOCK_CLASS(lock); 1512 if (witness_watch) { 1513 if ((lock->lo_flags & LO_UPGRADABLE) == 0) 1514 kassert_panic( 1515 "downgrade of non-upgradable lock (%s) %s @ %s:%d", 1516 class->lc_name, lock->lo_name, 1517 fixup_filename(file), line); 1518 if ((class->lc_flags & LC_SLEEPLOCK) == 0) 1519 kassert_panic( 1520 "downgrade of non-sleep lock (%s) %s @ %s:%d", 1521 class->lc_name, lock->lo_name, 1522 fixup_filename(file), line); 1523 } 1524 instance = find_instance(curthread->td_sleeplocks, lock); 1525 if (instance == NULL) { 1526 kassert_panic("downgrade of unlocked lock (%s) %s @ %s:%d", 1527 class->lc_name, lock->lo_name, 1528 fixup_filename(file), line); 1529 return; 1530 } 1531 if (witness_watch) { 1532 if ((instance->li_flags & LI_EXCLUSIVE) == 0) 1533 kassert_panic( 1534 "downgrade of shared lock (%s) %s @ %s:%d", 1535 class->lc_name, lock->lo_name, 1536 fixup_filename(file), line); 1537 if ((instance->li_flags & LI_RECURSEMASK) != 0) 1538 kassert_panic( 1539 "downgrade of recursed lock (%s) %s r=%d @ %s:%d", 1540 class->lc_name, lock->lo_name, 1541 instance->li_flags & LI_RECURSEMASK, 1542 fixup_filename(file), line); 1543 } 1544 instance->li_flags &= ~LI_EXCLUSIVE; 1545 } 1546 1547 void 1548 witness_unlock(struct lock_object *lock, int flags, const char *file, int line) 1549 { 1550 struct lock_list_entry **lock_list, *lle; 1551 struct lock_instance *instance; 1552 struct lock_class *class; 1553 struct thread *td; 1554 register_t s; 1555 int i, j; 1556 1557 if (witness_cold || lock->lo_witness == NULL || panicstr != NULL) 1558 return; 1559 td = curthread; 1560 class = LOCK_CLASS(lock); 1561 1562 /* Find lock instance associated with this lock. */ 1563 if (class->lc_flags & LC_SLEEPLOCK) 1564 lock_list = &td->td_sleeplocks; 1565 else 1566 lock_list = PCPU_PTR(spinlocks); 1567 lle = *lock_list; 1568 for (; *lock_list != NULL; lock_list = &(*lock_list)->ll_next) 1569 for (i = 0; i < (*lock_list)->ll_count; i++) { 1570 instance = &(*lock_list)->ll_children[i]; 1571 if (instance->li_lock == lock) 1572 goto found; 1573 } 1574 1575 /* 1576 * When disabling WITNESS through witness_watch we could end up in 1577 * having registered locks in the td_sleeplocks queue. 1578 * We have to make sure we flush these queues, so just search for 1579 * eventual register locks and remove them. 1580 */ 1581 if (witness_watch > 0) { 1582 kassert_panic("lock (%s) %s not locked @ %s:%d", class->lc_name, 1583 lock->lo_name, fixup_filename(file), line); 1584 return; 1585 } else { 1586 return; 1587 } 1588 found: 1589 1590 /* First, check for shared/exclusive mismatches. */ 1591 if ((instance->li_flags & LI_EXCLUSIVE) != 0 && witness_watch > 0 && 1592 (flags & LOP_EXCLUSIVE) == 0) { 1593 printf("shared unlock of (%s) %s @ %s:%d\n", class->lc_name, 1594 lock->lo_name, fixup_filename(file), line); 1595 printf("while exclusively locked from %s:%d\n", 1596 fixup_filename(instance->li_file), instance->li_line); 1597 kassert_panic("excl->ushare"); 1598 } 1599 if ((instance->li_flags & LI_EXCLUSIVE) == 0 && witness_watch > 0 && 1600 (flags & LOP_EXCLUSIVE) != 0) { 1601 printf("exclusive unlock of (%s) %s @ %s:%d\n", class->lc_name, 1602 lock->lo_name, fixup_filename(file), line); 1603 printf("while share locked from %s:%d\n", 1604 fixup_filename(instance->li_file), 1605 instance->li_line); 1606 kassert_panic("share->uexcl"); 1607 } 1608 /* If we are recursed, unrecurse. */ 1609 if ((instance->li_flags & LI_RECURSEMASK) > 0) { 1610 CTR4(KTR_WITNESS, "%s: pid %d unrecursed on %s r=%d", __func__, 1611 td->td_proc->p_pid, instance->li_lock->lo_name, 1612 instance->li_flags); 1613 instance->li_flags--; 1614 return; 1615 } 1616 /* The lock is now being dropped, check for NORELEASE flag */ 1617 if ((instance->li_flags & LI_NORELEASE) != 0 && witness_watch > 0) { 1618 printf("forbidden unlock of (%s) %s @ %s:%d\n", class->lc_name, 1619 lock->lo_name, fixup_filename(file), line); 1620 kassert_panic("lock marked norelease"); 1621 } 1622 1623 /* Otherwise, remove this item from the list. */ 1624 s = intr_disable(); 1625 CTR4(KTR_WITNESS, "%s: pid %d removed %s from lle[%d]", __func__, 1626 td->td_proc->p_pid, instance->li_lock->lo_name, 1627 (*lock_list)->ll_count - 1); 1628 for (j = i; j < (*lock_list)->ll_count - 1; j++) 1629 (*lock_list)->ll_children[j] = 1630 (*lock_list)->ll_children[j + 1]; 1631 (*lock_list)->ll_count--; 1632 intr_restore(s); 1633 1634 /* 1635 * In order to reduce contention on w_mtx, we want to keep always an 1636 * head object into lists so that frequent allocation from the 1637 * free witness pool (and subsequent locking) is avoided. 1638 * In order to maintain the current code simple, when the head 1639 * object is totally unloaded it means also that we do not have 1640 * further objects in the list, so the list ownership needs to be 1641 * hand over to another object if the current head needs to be freed. 1642 */ 1643 if ((*lock_list)->ll_count == 0) { 1644 if (*lock_list == lle) { 1645 if (lle->ll_next == NULL) 1646 return; 1647 } else 1648 lle = *lock_list; 1649 *lock_list = lle->ll_next; 1650 CTR3(KTR_WITNESS, "%s: pid %d removed lle %p", __func__, 1651 td->td_proc->p_pid, lle); 1652 witness_lock_list_free(lle); 1653 } 1654 } 1655 1656 void 1657 witness_thread_exit(struct thread *td) 1658 { 1659 struct lock_list_entry *lle; 1660 int i, n; 1661 1662 lle = td->td_sleeplocks; 1663 if (lle == NULL || panicstr != NULL) 1664 return; 1665 if (lle->ll_count != 0) { 1666 for (n = 0; lle != NULL; lle = lle->ll_next) 1667 for (i = lle->ll_count - 1; i >= 0; i--) { 1668 if (n == 0) 1669 printf("Thread %p exiting with the following locks held:\n", 1670 td); 1671 n++; 1672 witness_list_lock(&lle->ll_children[i], printf); 1673 1674 } 1675 kassert_panic( 1676 "Thread %p cannot exit while holding sleeplocks\n", td); 1677 } 1678 witness_lock_list_free(lle); 1679 } 1680 1681 /* 1682 * Warn if any locks other than 'lock' are held. Flags can be passed in to 1683 * exempt Giant and sleepable locks from the checks as well. If any 1684 * non-exempt locks are held, then a supplied message is printed to the 1685 * console along with a list of the offending locks. If indicated in the 1686 * flags then a failure results in a panic as well. 1687 */ 1688 int 1689 witness_warn(int flags, struct lock_object *lock, const char *fmt, ...) 1690 { 1691 struct lock_list_entry *lock_list, *lle; 1692 struct lock_instance *lock1; 1693 struct thread *td; 1694 va_list ap; 1695 int i, n; 1696 1697 if (witness_cold || witness_watch < 1 || panicstr != NULL) 1698 return (0); 1699 n = 0; 1700 td = curthread; 1701 for (lle = td->td_sleeplocks; lle != NULL; lle = lle->ll_next) 1702 for (i = lle->ll_count - 1; i >= 0; i--) { 1703 lock1 = &lle->ll_children[i]; 1704 if (lock1->li_lock == lock) 1705 continue; 1706 if (flags & WARN_GIANTOK && 1707 lock1->li_lock == &Giant.lock_object) 1708 continue; 1709 if (flags & WARN_SLEEPOK && 1710 (lock1->li_lock->lo_flags & LO_SLEEPABLE) != 0) 1711 continue; 1712 if (n == 0) { 1713 va_start(ap, fmt); 1714 vprintf(fmt, ap); 1715 va_end(ap); 1716 printf(" with the following"); 1717 if (flags & WARN_SLEEPOK) 1718 printf(" non-sleepable"); 1719 printf(" locks held:\n"); 1720 } 1721 n++; 1722 witness_list_lock(lock1, printf); 1723 } 1724 1725 /* 1726 * Pin the thread in order to avoid problems with thread migration. 1727 * Once that all verifies are passed about spinlocks ownership, 1728 * the thread is in a safe path and it can be unpinned. 1729 */ 1730 sched_pin(); 1731 lock_list = PCPU_GET(spinlocks); 1732 if (lock_list != NULL && lock_list->ll_count != 0) { 1733 sched_unpin(); 1734 1735 /* 1736 * We should only have one spinlock and as long as 1737 * the flags cannot match for this locks class, 1738 * check if the first spinlock is the one curthread 1739 * should hold. 1740 */ 1741 lock1 = &lock_list->ll_children[lock_list->ll_count - 1]; 1742 if (lock_list->ll_count == 1 && lock_list->ll_next == NULL && 1743 lock1->li_lock == lock && n == 0) 1744 return (0); 1745 1746 va_start(ap, fmt); 1747 vprintf(fmt, ap); 1748 va_end(ap); 1749 printf(" with the following"); 1750 if (flags & WARN_SLEEPOK) 1751 printf(" non-sleepable"); 1752 printf(" locks held:\n"); 1753 n += witness_list_locks(&lock_list, printf); 1754 } else 1755 sched_unpin(); 1756 if (flags & WARN_PANIC && n) 1757 kassert_panic("%s", __func__); 1758 else 1759 witness_debugger(n); 1760 return (n); 1761 } 1762 1763 const char * 1764 witness_file(struct lock_object *lock) 1765 { 1766 struct witness *w; 1767 1768 if (witness_cold || witness_watch < 1 || lock->lo_witness == NULL) 1769 return ("?"); 1770 w = lock->lo_witness; 1771 return (w->w_file); 1772 } 1773 1774 int 1775 witness_line(struct lock_object *lock) 1776 { 1777 struct witness *w; 1778 1779 if (witness_cold || witness_watch < 1 || lock->lo_witness == NULL) 1780 return (0); 1781 w = lock->lo_witness; 1782 return (w->w_line); 1783 } 1784 1785 static struct witness * 1786 enroll(const char *description, struct lock_class *lock_class) 1787 { 1788 struct witness *w; 1789 struct witness_list *typelist; 1790 1791 MPASS(description != NULL); 1792 1793 if (witness_watch == -1 || panicstr != NULL) 1794 return (NULL); 1795 if ((lock_class->lc_flags & LC_SPINLOCK)) { 1796 if (witness_skipspin) 1797 return (NULL); 1798 else 1799 typelist = &w_spin; 1800 } else if ((lock_class->lc_flags & LC_SLEEPLOCK)) { 1801 typelist = &w_sleep; 1802 } else { 1803 kassert_panic("lock class %s is not sleep or spin", 1804 lock_class->lc_name); 1805 return (NULL); 1806 } 1807 1808 mtx_lock_spin(&w_mtx); 1809 w = witness_hash_get(description); 1810 if (w) 1811 goto found; 1812 if ((w = witness_get()) == NULL) 1813 return (NULL); 1814 MPASS(strlen(description) < MAX_W_NAME); 1815 strcpy(w->w_name, description); 1816 w->w_class = lock_class; 1817 w->w_refcount = 1; 1818 STAILQ_INSERT_HEAD(&w_all, w, w_list); 1819 if (lock_class->lc_flags & LC_SPINLOCK) { 1820 STAILQ_INSERT_HEAD(&w_spin, w, w_typelist); 1821 w_spin_cnt++; 1822 } else if (lock_class->lc_flags & LC_SLEEPLOCK) { 1823 STAILQ_INSERT_HEAD(&w_sleep, w, w_typelist); 1824 w_sleep_cnt++; 1825 } 1826 1827 /* Insert new witness into the hash */ 1828 witness_hash_put(w); 1829 witness_increment_graph_generation(); 1830 mtx_unlock_spin(&w_mtx); 1831 return (w); 1832 found: 1833 w->w_refcount++; 1834 mtx_unlock_spin(&w_mtx); 1835 if (lock_class != w->w_class) 1836 kassert_panic( 1837 "lock (%s) %s does not match earlier (%s) lock", 1838 description, lock_class->lc_name, 1839 w->w_class->lc_name); 1840 return (w); 1841 } 1842 1843 static void 1844 depart(struct witness *w) 1845 { 1846 struct witness_list *list; 1847 1848 MPASS(w->w_refcount == 0); 1849 if (w->w_class->lc_flags & LC_SLEEPLOCK) { 1850 list = &w_sleep; 1851 w_sleep_cnt--; 1852 } else { 1853 list = &w_spin; 1854 w_spin_cnt--; 1855 } 1856 /* 1857 * Set file to NULL as it may point into a loadable module. 1858 */ 1859 w->w_file = NULL; 1860 w->w_line = 0; 1861 witness_increment_graph_generation(); 1862 } 1863 1864 1865 static void 1866 adopt(struct witness *parent, struct witness *child) 1867 { 1868 int pi, ci, i, j; 1869 1870 if (witness_cold == 0) 1871 mtx_assert(&w_mtx, MA_OWNED); 1872 1873 /* If the relationship is already known, there's no work to be done. */ 1874 if (isitmychild(parent, child)) 1875 return; 1876 1877 /* When the structure of the graph changes, bump up the generation. */ 1878 witness_increment_graph_generation(); 1879 1880 /* 1881 * The hard part ... create the direct relationship, then propagate all 1882 * indirect relationships. 1883 */ 1884 pi = parent->w_index; 1885 ci = child->w_index; 1886 WITNESS_INDEX_ASSERT(pi); 1887 WITNESS_INDEX_ASSERT(ci); 1888 MPASS(pi != ci); 1889 w_rmatrix[pi][ci] |= WITNESS_PARENT; 1890 w_rmatrix[ci][pi] |= WITNESS_CHILD; 1891 1892 /* 1893 * If parent was not already an ancestor of child, 1894 * then we increment the descendant and ancestor counters. 1895 */ 1896 if ((w_rmatrix[pi][ci] & WITNESS_ANCESTOR) == 0) { 1897 parent->w_num_descendants++; 1898 child->w_num_ancestors++; 1899 } 1900 1901 /* 1902 * Find each ancestor of 'pi'. Note that 'pi' itself is counted as 1903 * an ancestor of 'pi' during this loop. 1904 */ 1905 for (i = 1; i <= w_max_used_index; i++) { 1906 if ((w_rmatrix[i][pi] & WITNESS_ANCESTOR_MASK) == 0 && 1907 (i != pi)) 1908 continue; 1909 1910 /* Find each descendant of 'i' and mark it as a descendant. */ 1911 for (j = 1; j <= w_max_used_index; j++) { 1912 1913 /* 1914 * Skip children that are already marked as 1915 * descendants of 'i'. 1916 */ 1917 if (w_rmatrix[i][j] & WITNESS_ANCESTOR_MASK) 1918 continue; 1919 1920 /* 1921 * We are only interested in descendants of 'ci'. Note 1922 * that 'ci' itself is counted as a descendant of 'ci'. 1923 */ 1924 if ((w_rmatrix[ci][j] & WITNESS_ANCESTOR_MASK) == 0 && 1925 (j != ci)) 1926 continue; 1927 w_rmatrix[i][j] |= WITNESS_ANCESTOR; 1928 w_rmatrix[j][i] |= WITNESS_DESCENDANT; 1929 w_data[i].w_num_descendants++; 1930 w_data[j].w_num_ancestors++; 1931 1932 /* 1933 * Make sure we aren't marking a node as both an 1934 * ancestor and descendant. We should have caught 1935 * this as a lock order reversal earlier. 1936 */ 1937 if ((w_rmatrix[i][j] & WITNESS_ANCESTOR_MASK) && 1938 (w_rmatrix[i][j] & WITNESS_DESCENDANT_MASK)) { 1939 printf("witness rmatrix paradox! [%d][%d]=%d " 1940 "both ancestor and descendant\n", 1941 i, j, w_rmatrix[i][j]); 1942 kdb_backtrace(); 1943 printf("Witness disabled.\n"); 1944 witness_watch = -1; 1945 } 1946 if ((w_rmatrix[j][i] & WITNESS_ANCESTOR_MASK) && 1947 (w_rmatrix[j][i] & WITNESS_DESCENDANT_MASK)) { 1948 printf("witness rmatrix paradox! [%d][%d]=%d " 1949 "both ancestor and descendant\n", 1950 j, i, w_rmatrix[j][i]); 1951 kdb_backtrace(); 1952 printf("Witness disabled.\n"); 1953 witness_watch = -1; 1954 } 1955 } 1956 } 1957 } 1958 1959 static void 1960 itismychild(struct witness *parent, struct witness *child) 1961 { 1962 int unlocked; 1963 1964 MPASS(child != NULL && parent != NULL); 1965 if (witness_cold == 0) 1966 mtx_assert(&w_mtx, MA_OWNED); 1967 1968 if (!witness_lock_type_equal(parent, child)) { 1969 if (witness_cold == 0) { 1970 unlocked = 1; 1971 mtx_unlock_spin(&w_mtx); 1972 } else { 1973 unlocked = 0; 1974 } 1975 kassert_panic( 1976 "%s: parent \"%s\" (%s) and child \"%s\" (%s) are not " 1977 "the same lock type", __func__, parent->w_name, 1978 parent->w_class->lc_name, child->w_name, 1979 child->w_class->lc_name); 1980 if (unlocked) 1981 mtx_lock_spin(&w_mtx); 1982 } 1983 adopt(parent, child); 1984 } 1985 1986 /* 1987 * Generic code for the isitmy*() functions. The rmask parameter is the 1988 * expected relationship of w1 to w2. 1989 */ 1990 static int 1991 _isitmyx(struct witness *w1, struct witness *w2, int rmask, const char *fname) 1992 { 1993 unsigned char r1, r2; 1994 int i1, i2; 1995 1996 i1 = w1->w_index; 1997 i2 = w2->w_index; 1998 WITNESS_INDEX_ASSERT(i1); 1999 WITNESS_INDEX_ASSERT(i2); 2000 r1 = w_rmatrix[i1][i2] & WITNESS_RELATED_MASK; 2001 r2 = w_rmatrix[i2][i1] & WITNESS_RELATED_MASK; 2002 2003 /* The flags on one better be the inverse of the flags on the other */ 2004 if (!((WITNESS_ATOD(r1) == r2 && WITNESS_DTOA(r2) == r1) || 2005 (WITNESS_DTOA(r1) == r2 && WITNESS_ATOD(r2) == r1))) { 2006 printf("%s: rmatrix mismatch between %s (index %d) and %s " 2007 "(index %d): w_rmatrix[%d][%d] == %hhx but " 2008 "w_rmatrix[%d][%d] == %hhx\n", 2009 fname, w1->w_name, i1, w2->w_name, i2, i1, i2, r1, 2010 i2, i1, r2); 2011 kdb_backtrace(); 2012 printf("Witness disabled.\n"); 2013 witness_watch = -1; 2014 } 2015 return (r1 & rmask); 2016 } 2017 2018 /* 2019 * Checks if @child is a direct child of @parent. 2020 */ 2021 static int 2022 isitmychild(struct witness *parent, struct witness *child) 2023 { 2024 2025 return (_isitmyx(parent, child, WITNESS_PARENT, __func__)); 2026 } 2027 2028 /* 2029 * Checks if @descendant is a direct or inderect descendant of @ancestor. 2030 */ 2031 static int 2032 isitmydescendant(struct witness *ancestor, struct witness *descendant) 2033 { 2034 2035 return (_isitmyx(ancestor, descendant, WITNESS_ANCESTOR_MASK, 2036 __func__)); 2037 } 2038 2039 #ifdef BLESSING 2040 static int 2041 blessed(struct witness *w1, struct witness *w2) 2042 { 2043 int i; 2044 struct witness_blessed *b; 2045 2046 for (i = 0; i < blessed_count; i++) { 2047 b = &blessed_list[i]; 2048 if (strcmp(w1->w_name, b->b_lock1) == 0) { 2049 if (strcmp(w2->w_name, b->b_lock2) == 0) 2050 return (1); 2051 continue; 2052 } 2053 if (strcmp(w1->w_name, b->b_lock2) == 0) 2054 if (strcmp(w2->w_name, b->b_lock1) == 0) 2055 return (1); 2056 } 2057 return (0); 2058 } 2059 #endif 2060 2061 static struct witness * 2062 witness_get(void) 2063 { 2064 struct witness *w; 2065 int index; 2066 2067 if (witness_cold == 0) 2068 mtx_assert(&w_mtx, MA_OWNED); 2069 2070 if (witness_watch == -1) { 2071 mtx_unlock_spin(&w_mtx); 2072 return (NULL); 2073 } 2074 if (STAILQ_EMPTY(&w_free)) { 2075 witness_watch = -1; 2076 mtx_unlock_spin(&w_mtx); 2077 printf("WITNESS: unable to allocate a new witness object\n"); 2078 return (NULL); 2079 } 2080 w = STAILQ_FIRST(&w_free); 2081 STAILQ_REMOVE_HEAD(&w_free, w_list); 2082 w_free_cnt--; 2083 index = w->w_index; 2084 MPASS(index > 0 && index == w_max_used_index+1 && 2085 index < WITNESS_COUNT); 2086 bzero(w, sizeof(*w)); 2087 w->w_index = index; 2088 if (index > w_max_used_index) 2089 w_max_used_index = index; 2090 return (w); 2091 } 2092 2093 static void 2094 witness_free(struct witness *w) 2095 { 2096 2097 STAILQ_INSERT_HEAD(&w_free, w, w_list); 2098 w_free_cnt++; 2099 } 2100 2101 static struct lock_list_entry * 2102 witness_lock_list_get(void) 2103 { 2104 struct lock_list_entry *lle; 2105 2106 if (witness_watch == -1) 2107 return (NULL); 2108 mtx_lock_spin(&w_mtx); 2109 lle = w_lock_list_free; 2110 if (lle == NULL) { 2111 witness_watch = -1; 2112 mtx_unlock_spin(&w_mtx); 2113 printf("%s: witness exhausted\n", __func__); 2114 return (NULL); 2115 } 2116 w_lock_list_free = lle->ll_next; 2117 mtx_unlock_spin(&w_mtx); 2118 bzero(lle, sizeof(*lle)); 2119 return (lle); 2120 } 2121 2122 static void 2123 witness_lock_list_free(struct lock_list_entry *lle) 2124 { 2125 2126 mtx_lock_spin(&w_mtx); 2127 lle->ll_next = w_lock_list_free; 2128 w_lock_list_free = lle; 2129 mtx_unlock_spin(&w_mtx); 2130 } 2131 2132 static struct lock_instance * 2133 find_instance(struct lock_list_entry *list, const struct lock_object *lock) 2134 { 2135 struct lock_list_entry *lle; 2136 struct lock_instance *instance; 2137 int i; 2138 2139 for (lle = list; lle != NULL; lle = lle->ll_next) 2140 for (i = lle->ll_count - 1; i >= 0; i--) { 2141 instance = &lle->ll_children[i]; 2142 if (instance->li_lock == lock) 2143 return (instance); 2144 } 2145 return (NULL); 2146 } 2147 2148 static void 2149 witness_list_lock(struct lock_instance *instance, 2150 int (*prnt)(const char *fmt, ...)) 2151 { 2152 struct lock_object *lock; 2153 2154 lock = instance->li_lock; 2155 prnt("%s %s %s", (instance->li_flags & LI_EXCLUSIVE) != 0 ? 2156 "exclusive" : "shared", LOCK_CLASS(lock)->lc_name, lock->lo_name); 2157 if (lock->lo_witness->w_name != lock->lo_name) 2158 prnt(" (%s)", lock->lo_witness->w_name); 2159 prnt(" r = %d (%p) locked @ %s:%d\n", 2160 instance->li_flags & LI_RECURSEMASK, lock, 2161 fixup_filename(instance->li_file), instance->li_line); 2162 } 2163 2164 #ifdef DDB 2165 static int 2166 witness_thread_has_locks(struct thread *td) 2167 { 2168 2169 if (td->td_sleeplocks == NULL) 2170 return (0); 2171 return (td->td_sleeplocks->ll_count != 0); 2172 } 2173 2174 static int 2175 witness_proc_has_locks(struct proc *p) 2176 { 2177 struct thread *td; 2178 2179 FOREACH_THREAD_IN_PROC(p, td) { 2180 if (witness_thread_has_locks(td)) 2181 return (1); 2182 } 2183 return (0); 2184 } 2185 #endif 2186 2187 int 2188 witness_list_locks(struct lock_list_entry **lock_list, 2189 int (*prnt)(const char *fmt, ...)) 2190 { 2191 struct lock_list_entry *lle; 2192 int i, nheld; 2193 2194 nheld = 0; 2195 for (lle = *lock_list; lle != NULL; lle = lle->ll_next) 2196 for (i = lle->ll_count - 1; i >= 0; i--) { 2197 witness_list_lock(&lle->ll_children[i], prnt); 2198 nheld++; 2199 } 2200 return (nheld); 2201 } 2202 2203 /* 2204 * This is a bit risky at best. We call this function when we have timed 2205 * out acquiring a spin lock, and we assume that the other CPU is stuck 2206 * with this lock held. So, we go groveling around in the other CPU's 2207 * per-cpu data to try to find the lock instance for this spin lock to 2208 * see when it was last acquired. 2209 */ 2210 void 2211 witness_display_spinlock(struct lock_object *lock, struct thread *owner, 2212 int (*prnt)(const char *fmt, ...)) 2213 { 2214 struct lock_instance *instance; 2215 struct pcpu *pc; 2216 2217 if (owner->td_critnest == 0 || owner->td_oncpu == NOCPU) 2218 return; 2219 pc = pcpu_find(owner->td_oncpu); 2220 instance = find_instance(pc->pc_spinlocks, lock); 2221 if (instance != NULL) 2222 witness_list_lock(instance, prnt); 2223 } 2224 2225 void 2226 witness_save(struct lock_object *lock, const char **filep, int *linep) 2227 { 2228 struct lock_list_entry *lock_list; 2229 struct lock_instance *instance; 2230 struct lock_class *class; 2231 2232 /* 2233 * This function is used independently in locking code to deal with 2234 * Giant, SCHEDULER_STOPPED() check can be removed here after Giant 2235 * is gone. 2236 */ 2237 if (SCHEDULER_STOPPED()) 2238 return; 2239 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); 2240 if (lock->lo_witness == NULL || witness_watch == -1 || panicstr != NULL) 2241 return; 2242 class = LOCK_CLASS(lock); 2243 if (class->lc_flags & LC_SLEEPLOCK) 2244 lock_list = curthread->td_sleeplocks; 2245 else { 2246 if (witness_skipspin) 2247 return; 2248 lock_list = PCPU_GET(spinlocks); 2249 } 2250 instance = find_instance(lock_list, lock); 2251 if (instance == NULL) { 2252 kassert_panic("%s: lock (%s) %s not locked", __func__, 2253 class->lc_name, lock->lo_name); 2254 return; 2255 } 2256 *filep = instance->li_file; 2257 *linep = instance->li_line; 2258 } 2259 2260 void 2261 witness_restore(struct lock_object *lock, const char *file, int line) 2262 { 2263 struct lock_list_entry *lock_list; 2264 struct lock_instance *instance; 2265 struct lock_class *class; 2266 2267 /* 2268 * This function is used independently in locking code to deal with 2269 * Giant, SCHEDULER_STOPPED() check can be removed here after Giant 2270 * is gone. 2271 */ 2272 if (SCHEDULER_STOPPED()) 2273 return; 2274 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); 2275 if (lock->lo_witness == NULL || witness_watch == -1 || panicstr != NULL) 2276 return; 2277 class = LOCK_CLASS(lock); 2278 if (class->lc_flags & LC_SLEEPLOCK) 2279 lock_list = curthread->td_sleeplocks; 2280 else { 2281 if (witness_skipspin) 2282 return; 2283 lock_list = PCPU_GET(spinlocks); 2284 } 2285 instance = find_instance(lock_list, lock); 2286 if (instance == NULL) 2287 kassert_panic("%s: lock (%s) %s not locked", __func__, 2288 class->lc_name, lock->lo_name); 2289 lock->lo_witness->w_file = file; 2290 lock->lo_witness->w_line = line; 2291 if (instance == NULL) 2292 return; 2293 instance->li_file = file; 2294 instance->li_line = line; 2295 } 2296 2297 void 2298 witness_assert(const struct lock_object *lock, int flags, const char *file, 2299 int line) 2300 { 2301 #ifdef INVARIANT_SUPPORT 2302 struct lock_instance *instance; 2303 struct lock_class *class; 2304 2305 if (lock->lo_witness == NULL || witness_watch < 1 || panicstr != NULL) 2306 return; 2307 class = LOCK_CLASS(lock); 2308 if ((class->lc_flags & LC_SLEEPLOCK) != 0) 2309 instance = find_instance(curthread->td_sleeplocks, lock); 2310 else if ((class->lc_flags & LC_SPINLOCK) != 0) 2311 instance = find_instance(PCPU_GET(spinlocks), lock); 2312 else { 2313 kassert_panic("Lock (%s) %s is not sleep or spin!", 2314 class->lc_name, lock->lo_name); 2315 return; 2316 } 2317 switch (flags) { 2318 case LA_UNLOCKED: 2319 if (instance != NULL) 2320 kassert_panic("Lock (%s) %s locked @ %s:%d.", 2321 class->lc_name, lock->lo_name, 2322 fixup_filename(file), line); 2323 break; 2324 case LA_LOCKED: 2325 case LA_LOCKED | LA_RECURSED: 2326 case LA_LOCKED | LA_NOTRECURSED: 2327 case LA_SLOCKED: 2328 case LA_SLOCKED | LA_RECURSED: 2329 case LA_SLOCKED | LA_NOTRECURSED: 2330 case LA_XLOCKED: 2331 case LA_XLOCKED | LA_RECURSED: 2332 case LA_XLOCKED | LA_NOTRECURSED: 2333 if (instance == NULL) { 2334 kassert_panic("Lock (%s) %s not locked @ %s:%d.", 2335 class->lc_name, lock->lo_name, 2336 fixup_filename(file), line); 2337 break; 2338 } 2339 if ((flags & LA_XLOCKED) != 0 && 2340 (instance->li_flags & LI_EXCLUSIVE) == 0) 2341 kassert_panic( 2342 "Lock (%s) %s not exclusively locked @ %s:%d.", 2343 class->lc_name, lock->lo_name, 2344 fixup_filename(file), line); 2345 if ((flags & LA_SLOCKED) != 0 && 2346 (instance->li_flags & LI_EXCLUSIVE) != 0) 2347 kassert_panic( 2348 "Lock (%s) %s exclusively locked @ %s:%d.", 2349 class->lc_name, lock->lo_name, 2350 fixup_filename(file), line); 2351 if ((flags & LA_RECURSED) != 0 && 2352 (instance->li_flags & LI_RECURSEMASK) == 0) 2353 kassert_panic("Lock (%s) %s not recursed @ %s:%d.", 2354 class->lc_name, lock->lo_name, 2355 fixup_filename(file), line); 2356 if ((flags & LA_NOTRECURSED) != 0 && 2357 (instance->li_flags & LI_RECURSEMASK) != 0) 2358 kassert_panic("Lock (%s) %s recursed @ %s:%d.", 2359 class->lc_name, lock->lo_name, 2360 fixup_filename(file), line); 2361 break; 2362 default: 2363 kassert_panic("Invalid lock assertion at %s:%d.", 2364 fixup_filename(file), line); 2365 2366 } 2367 #endif /* INVARIANT_SUPPORT */ 2368 } 2369 2370 static void 2371 witness_setflag(struct lock_object *lock, int flag, int set) 2372 { 2373 struct lock_list_entry *lock_list; 2374 struct lock_instance *instance; 2375 struct lock_class *class; 2376 2377 if (lock->lo_witness == NULL || witness_watch == -1 || panicstr != NULL) 2378 return; 2379 class = LOCK_CLASS(lock); 2380 if (class->lc_flags & LC_SLEEPLOCK) 2381 lock_list = curthread->td_sleeplocks; 2382 else { 2383 if (witness_skipspin) 2384 return; 2385 lock_list = PCPU_GET(spinlocks); 2386 } 2387 instance = find_instance(lock_list, lock); 2388 if (instance == NULL) { 2389 kassert_panic("%s: lock (%s) %s not locked", __func__, 2390 class->lc_name, lock->lo_name); 2391 return; 2392 } 2393 2394 if (set) 2395 instance->li_flags |= flag; 2396 else 2397 instance->li_flags &= ~flag; 2398 } 2399 2400 void 2401 witness_norelease(struct lock_object *lock) 2402 { 2403 2404 witness_setflag(lock, LI_NORELEASE, 1); 2405 } 2406 2407 void 2408 witness_releaseok(struct lock_object *lock) 2409 { 2410 2411 witness_setflag(lock, LI_NORELEASE, 0); 2412 } 2413 2414 #ifdef DDB 2415 static void 2416 witness_ddb_list(struct thread *td) 2417 { 2418 2419 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); 2420 KASSERT(kdb_active, ("%s: not in the debugger", __func__)); 2421 2422 if (witness_watch < 1) 2423 return; 2424 2425 witness_list_locks(&td->td_sleeplocks, db_printf); 2426 2427 /* 2428 * We only handle spinlocks if td == curthread. This is somewhat broken 2429 * if td is currently executing on some other CPU and holds spin locks 2430 * as we won't display those locks. If we had a MI way of getting 2431 * the per-cpu data for a given cpu then we could use 2432 * td->td_oncpu to get the list of spinlocks for this thread 2433 * and "fix" this. 2434 * 2435 * That still wouldn't really fix this unless we locked the scheduler 2436 * lock or stopped the other CPU to make sure it wasn't changing the 2437 * list out from under us. It is probably best to just not try to 2438 * handle threads on other CPU's for now. 2439 */ 2440 if (td == curthread && PCPU_GET(spinlocks) != NULL) 2441 witness_list_locks(PCPU_PTR(spinlocks), db_printf); 2442 } 2443 2444 DB_SHOW_COMMAND(locks, db_witness_list) 2445 { 2446 struct thread *td; 2447 2448 if (have_addr) 2449 td = db_lookup_thread(addr, TRUE); 2450 else 2451 td = kdb_thread; 2452 witness_ddb_list(td); 2453 } 2454 2455 DB_SHOW_ALL_COMMAND(locks, db_witness_list_all) 2456 { 2457 struct thread *td; 2458 struct proc *p; 2459 2460 /* 2461 * It would be nice to list only threads and processes that actually 2462 * held sleep locks, but that information is currently not exported 2463 * by WITNESS. 2464 */ 2465 FOREACH_PROC_IN_SYSTEM(p) { 2466 if (!witness_proc_has_locks(p)) 2467 continue; 2468 FOREACH_THREAD_IN_PROC(p, td) { 2469 if (!witness_thread_has_locks(td)) 2470 continue; 2471 db_printf("Process %d (%s) thread %p (%d)\n", p->p_pid, 2472 p->p_comm, td, td->td_tid); 2473 witness_ddb_list(td); 2474 if (db_pager_quit) 2475 return; 2476 } 2477 } 2478 } 2479 DB_SHOW_ALIAS(alllocks, db_witness_list_all) 2480 2481 DB_SHOW_COMMAND(witness, db_witness_display) 2482 { 2483 2484 witness_ddb_display(db_printf); 2485 } 2486 #endif 2487 2488 static int 2489 sysctl_debug_witness_badstacks(SYSCTL_HANDLER_ARGS) 2490 { 2491 struct witness_lock_order_data *data1, *data2, *tmp_data1, *tmp_data2; 2492 struct witness *tmp_w1, *tmp_w2, *w1, *w2; 2493 struct sbuf *sb; 2494 u_int w_rmatrix1, w_rmatrix2; 2495 int error, generation, i, j; 2496 2497 tmp_data1 = NULL; 2498 tmp_data2 = NULL; 2499 tmp_w1 = NULL; 2500 tmp_w2 = NULL; 2501 if (witness_watch < 1) { 2502 error = SYSCTL_OUT(req, w_notrunning, sizeof(w_notrunning)); 2503 return (error); 2504 } 2505 if (witness_cold) { 2506 error = SYSCTL_OUT(req, w_stillcold, sizeof(w_stillcold)); 2507 return (error); 2508 } 2509 error = 0; 2510 sb = sbuf_new(NULL, NULL, BADSTACK_SBUF_SIZE, SBUF_AUTOEXTEND); 2511 if (sb == NULL) 2512 return (ENOMEM); 2513 2514 /* Allocate and init temporary storage space. */ 2515 tmp_w1 = malloc(sizeof(struct witness), M_TEMP, M_WAITOK | M_ZERO); 2516 tmp_w2 = malloc(sizeof(struct witness), M_TEMP, M_WAITOK | M_ZERO); 2517 tmp_data1 = malloc(sizeof(struct witness_lock_order_data), M_TEMP, 2518 M_WAITOK | M_ZERO); 2519 tmp_data2 = malloc(sizeof(struct witness_lock_order_data), M_TEMP, 2520 M_WAITOK | M_ZERO); 2521 stack_zero(&tmp_data1->wlod_stack); 2522 stack_zero(&tmp_data2->wlod_stack); 2523 2524 restart: 2525 mtx_lock_spin(&w_mtx); 2526 generation = w_generation; 2527 mtx_unlock_spin(&w_mtx); 2528 sbuf_printf(sb, "Number of known direct relationships is %d\n", 2529 w_lohash.wloh_count); 2530 for (i = 1; i < w_max_used_index; i++) { 2531 mtx_lock_spin(&w_mtx); 2532 if (generation != w_generation) { 2533 mtx_unlock_spin(&w_mtx); 2534 2535 /* The graph has changed, try again. */ 2536 req->oldidx = 0; 2537 sbuf_clear(sb); 2538 goto restart; 2539 } 2540 2541 w1 = &w_data[i]; 2542 if (w1->w_reversed == 0) { 2543 mtx_unlock_spin(&w_mtx); 2544 continue; 2545 } 2546 2547 /* Copy w1 locally so we can release the spin lock. */ 2548 *tmp_w1 = *w1; 2549 mtx_unlock_spin(&w_mtx); 2550 2551 if (tmp_w1->w_reversed == 0) 2552 continue; 2553 for (j = 1; j < w_max_used_index; j++) { 2554 if ((w_rmatrix[i][j] & WITNESS_REVERSAL) == 0 || i > j) 2555 continue; 2556 2557 mtx_lock_spin(&w_mtx); 2558 if (generation != w_generation) { 2559 mtx_unlock_spin(&w_mtx); 2560 2561 /* The graph has changed, try again. */ 2562 req->oldidx = 0; 2563 sbuf_clear(sb); 2564 goto restart; 2565 } 2566 2567 w2 = &w_data[j]; 2568 data1 = witness_lock_order_get(w1, w2); 2569 data2 = witness_lock_order_get(w2, w1); 2570 2571 /* 2572 * Copy information locally so we can release the 2573 * spin lock. 2574 */ 2575 *tmp_w2 = *w2; 2576 w_rmatrix1 = (unsigned int)w_rmatrix[i][j]; 2577 w_rmatrix2 = (unsigned int)w_rmatrix[j][i]; 2578 2579 if (data1) { 2580 stack_zero(&tmp_data1->wlod_stack); 2581 stack_copy(&data1->wlod_stack, 2582 &tmp_data1->wlod_stack); 2583 } 2584 if (data2 && data2 != data1) { 2585 stack_zero(&tmp_data2->wlod_stack); 2586 stack_copy(&data2->wlod_stack, 2587 &tmp_data2->wlod_stack); 2588 } 2589 mtx_unlock_spin(&w_mtx); 2590 2591 sbuf_printf(sb, 2592 "\nLock order reversal between \"%s\"(%s) and \"%s\"(%s)!\n", 2593 tmp_w1->w_name, tmp_w1->w_class->lc_name, 2594 tmp_w2->w_name, tmp_w2->w_class->lc_name); 2595 #if 0 2596 sbuf_printf(sb, 2597 "w_rmatrix[%s][%s] == %x, w_rmatrix[%s][%s] == %x\n", 2598 tmp_w1->name, tmp_w2->w_name, w_rmatrix1, 2599 tmp_w2->name, tmp_w1->w_name, w_rmatrix2); 2600 #endif 2601 if (data1) { 2602 sbuf_printf(sb, 2603 "Lock order \"%s\"(%s) -> \"%s\"(%s) first seen at:\n", 2604 tmp_w1->w_name, tmp_w1->w_class->lc_name, 2605 tmp_w2->w_name, tmp_w2->w_class->lc_name); 2606 stack_sbuf_print(sb, &tmp_data1->wlod_stack); 2607 sbuf_printf(sb, "\n"); 2608 } 2609 if (data2 && data2 != data1) { 2610 sbuf_printf(sb, 2611 "Lock order \"%s\"(%s) -> \"%s\"(%s) first seen at:\n", 2612 tmp_w2->w_name, tmp_w2->w_class->lc_name, 2613 tmp_w1->w_name, tmp_w1->w_class->lc_name); 2614 stack_sbuf_print(sb, &tmp_data2->wlod_stack); 2615 sbuf_printf(sb, "\n"); 2616 } 2617 } 2618 } 2619 mtx_lock_spin(&w_mtx); 2620 if (generation != w_generation) { 2621 mtx_unlock_spin(&w_mtx); 2622 2623 /* 2624 * The graph changed while we were printing stack data, 2625 * try again. 2626 */ 2627 req->oldidx = 0; 2628 sbuf_clear(sb); 2629 goto restart; 2630 } 2631 mtx_unlock_spin(&w_mtx); 2632 2633 /* Free temporary storage space. */ 2634 free(tmp_data1, M_TEMP); 2635 free(tmp_data2, M_TEMP); 2636 free(tmp_w1, M_TEMP); 2637 free(tmp_w2, M_TEMP); 2638 2639 sbuf_finish(sb); 2640 error = SYSCTL_OUT(req, sbuf_data(sb), sbuf_len(sb) + 1); 2641 sbuf_delete(sb); 2642 2643 return (error); 2644 } 2645 2646 static int 2647 sysctl_debug_witness_fullgraph(SYSCTL_HANDLER_ARGS) 2648 { 2649 struct witness *w; 2650 struct sbuf *sb; 2651 int error; 2652 2653 if (witness_watch < 1) { 2654 error = SYSCTL_OUT(req, w_notrunning, sizeof(w_notrunning)); 2655 return (error); 2656 } 2657 if (witness_cold) { 2658 error = SYSCTL_OUT(req, w_stillcold, sizeof(w_stillcold)); 2659 return (error); 2660 } 2661 error = 0; 2662 2663 error = sysctl_wire_old_buffer(req, 0); 2664 if (error != 0) 2665 return (error); 2666 sb = sbuf_new_for_sysctl(NULL, NULL, FULLGRAPH_SBUF_SIZE, req); 2667 if (sb == NULL) 2668 return (ENOMEM); 2669 sbuf_printf(sb, "\n"); 2670 2671 mtx_lock_spin(&w_mtx); 2672 STAILQ_FOREACH(w, &w_all, w_list) 2673 w->w_displayed = 0; 2674 STAILQ_FOREACH(w, &w_all, w_list) 2675 witness_add_fullgraph(sb, w); 2676 mtx_unlock_spin(&w_mtx); 2677 2678 /* 2679 * Close the sbuf and return to userland. 2680 */ 2681 error = sbuf_finish(sb); 2682 sbuf_delete(sb); 2683 2684 return (error); 2685 } 2686 2687 static int 2688 sysctl_debug_witness_watch(SYSCTL_HANDLER_ARGS) 2689 { 2690 int error, value; 2691 2692 value = witness_watch; 2693 error = sysctl_handle_int(oidp, &value, 0, req); 2694 if (error != 0 || req->newptr == NULL) 2695 return (error); 2696 if (value > 1 || value < -1 || 2697 (witness_watch == -1 && value != witness_watch)) 2698 return (EINVAL); 2699 witness_watch = value; 2700 return (0); 2701 } 2702 2703 static void 2704 witness_add_fullgraph(struct sbuf *sb, struct witness *w) 2705 { 2706 int i; 2707 2708 if (w->w_displayed != 0 || (w->w_file == NULL && w->w_line == 0)) 2709 return; 2710 w->w_displayed = 1; 2711 2712 WITNESS_INDEX_ASSERT(w->w_index); 2713 for (i = 1; i <= w_max_used_index; i++) { 2714 if (w_rmatrix[w->w_index][i] & WITNESS_PARENT) { 2715 sbuf_printf(sb, "\"%s\",\"%s\"\n", w->w_name, 2716 w_data[i].w_name); 2717 witness_add_fullgraph(sb, &w_data[i]); 2718 } 2719 } 2720 } 2721 2722 /* 2723 * A simple hash function. Takes a key pointer and a key size. If size == 0, 2724 * interprets the key as a string and reads until the null 2725 * terminator. Otherwise, reads the first size bytes. Returns an unsigned 32-bit 2726 * hash value computed from the key. 2727 */ 2728 static uint32_t 2729 witness_hash_djb2(const uint8_t *key, uint32_t size) 2730 { 2731 unsigned int hash = 5381; 2732 int i; 2733 2734 /* hash = hash * 33 + key[i] */ 2735 if (size) 2736 for (i = 0; i < size; i++) 2737 hash = ((hash << 5) + hash) + (unsigned int)key[i]; 2738 else 2739 for (i = 0; key[i] != 0; i++) 2740 hash = ((hash << 5) + hash) + (unsigned int)key[i]; 2741 2742 return (hash); 2743 } 2744 2745 2746 /* 2747 * Initializes the two witness hash tables. Called exactly once from 2748 * witness_initialize(). 2749 */ 2750 static void 2751 witness_init_hash_tables(void) 2752 { 2753 int i; 2754 2755 MPASS(witness_cold); 2756 2757 /* Initialize the hash tables. */ 2758 for (i = 0; i < WITNESS_HASH_SIZE; i++) 2759 w_hash.wh_array[i] = NULL; 2760 2761 w_hash.wh_size = WITNESS_HASH_SIZE; 2762 w_hash.wh_count = 0; 2763 2764 /* Initialize the lock order data hash. */ 2765 w_lofree = NULL; 2766 for (i = 0; i < WITNESS_LO_DATA_COUNT; i++) { 2767 memset(&w_lodata[i], 0, sizeof(w_lodata[i])); 2768 w_lodata[i].wlod_next = w_lofree; 2769 w_lofree = &w_lodata[i]; 2770 } 2771 w_lohash.wloh_size = WITNESS_LO_HASH_SIZE; 2772 w_lohash.wloh_count = 0; 2773 for (i = 0; i < WITNESS_LO_HASH_SIZE; i++) 2774 w_lohash.wloh_array[i] = NULL; 2775 } 2776 2777 static struct witness * 2778 witness_hash_get(const char *key) 2779 { 2780 struct witness *w; 2781 uint32_t hash; 2782 2783 MPASS(key != NULL); 2784 if (witness_cold == 0) 2785 mtx_assert(&w_mtx, MA_OWNED); 2786 hash = witness_hash_djb2(key, 0) % w_hash.wh_size; 2787 w = w_hash.wh_array[hash]; 2788 while (w != NULL) { 2789 if (strcmp(w->w_name, key) == 0) 2790 goto out; 2791 w = w->w_hash_next; 2792 } 2793 2794 out: 2795 return (w); 2796 } 2797 2798 static void 2799 witness_hash_put(struct witness *w) 2800 { 2801 uint32_t hash; 2802 2803 MPASS(w != NULL); 2804 MPASS(w->w_name != NULL); 2805 if (witness_cold == 0) 2806 mtx_assert(&w_mtx, MA_OWNED); 2807 KASSERT(witness_hash_get(w->w_name) == NULL, 2808 ("%s: trying to add a hash entry that already exists!", __func__)); 2809 KASSERT(w->w_hash_next == NULL, 2810 ("%s: w->w_hash_next != NULL", __func__)); 2811 2812 hash = witness_hash_djb2(w->w_name, 0) % w_hash.wh_size; 2813 w->w_hash_next = w_hash.wh_array[hash]; 2814 w_hash.wh_array[hash] = w; 2815 w_hash.wh_count++; 2816 } 2817 2818 2819 static struct witness_lock_order_data * 2820 witness_lock_order_get(struct witness *parent, struct witness *child) 2821 { 2822 struct witness_lock_order_data *data = NULL; 2823 struct witness_lock_order_key key; 2824 unsigned int hash; 2825 2826 MPASS(parent != NULL && child != NULL); 2827 key.from = parent->w_index; 2828 key.to = child->w_index; 2829 WITNESS_INDEX_ASSERT(key.from); 2830 WITNESS_INDEX_ASSERT(key.to); 2831 if ((w_rmatrix[parent->w_index][child->w_index] 2832 & WITNESS_LOCK_ORDER_KNOWN) == 0) 2833 goto out; 2834 2835 hash = witness_hash_djb2((const char*)&key, 2836 sizeof(key)) % w_lohash.wloh_size; 2837 data = w_lohash.wloh_array[hash]; 2838 while (data != NULL) { 2839 if (witness_lock_order_key_equal(&data->wlod_key, &key)) 2840 break; 2841 data = data->wlod_next; 2842 } 2843 2844 out: 2845 return (data); 2846 } 2847 2848 /* 2849 * Verify that parent and child have a known relationship, are not the same, 2850 * and child is actually a child of parent. This is done without w_mtx 2851 * to avoid contention in the common case. 2852 */ 2853 static int 2854 witness_lock_order_check(struct witness *parent, struct witness *child) 2855 { 2856 2857 if (parent != child && 2858 w_rmatrix[parent->w_index][child->w_index] 2859 & WITNESS_LOCK_ORDER_KNOWN && 2860 isitmychild(parent, child)) 2861 return (1); 2862 2863 return (0); 2864 } 2865 2866 static int 2867 witness_lock_order_add(struct witness *parent, struct witness *child) 2868 { 2869 struct witness_lock_order_data *data = NULL; 2870 struct witness_lock_order_key key; 2871 unsigned int hash; 2872 2873 MPASS(parent != NULL && child != NULL); 2874 key.from = parent->w_index; 2875 key.to = child->w_index; 2876 WITNESS_INDEX_ASSERT(key.from); 2877 WITNESS_INDEX_ASSERT(key.to); 2878 if (w_rmatrix[parent->w_index][child->w_index] 2879 & WITNESS_LOCK_ORDER_KNOWN) 2880 return (1); 2881 2882 hash = witness_hash_djb2((const char*)&key, 2883 sizeof(key)) % w_lohash.wloh_size; 2884 w_rmatrix[parent->w_index][child->w_index] |= WITNESS_LOCK_ORDER_KNOWN; 2885 data = w_lofree; 2886 if (data == NULL) 2887 return (0); 2888 w_lofree = data->wlod_next; 2889 data->wlod_next = w_lohash.wloh_array[hash]; 2890 data->wlod_key = key; 2891 w_lohash.wloh_array[hash] = data; 2892 w_lohash.wloh_count++; 2893 stack_zero(&data->wlod_stack); 2894 stack_save(&data->wlod_stack); 2895 return (1); 2896 } 2897 2898 /* Call this whenver the structure of the witness graph changes. */ 2899 static void 2900 witness_increment_graph_generation(void) 2901 { 2902 2903 if (witness_cold == 0) 2904 mtx_assert(&w_mtx, MA_OWNED); 2905 w_generation++; 2906 } 2907 2908 #ifdef KDB 2909 static void 2910 _witness_debugger(int cond, const char *msg) 2911 { 2912 2913 if (witness_trace && cond) 2914 kdb_backtrace(); 2915 if (witness_kdb && cond) 2916 kdb_enter(KDB_WHY_WITNESS, msg); 2917 } 2918 #endif 2919