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_mtx_sleep }, 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 { "system map", &lock_class_mtx_sleep }, 597 { "vm page queue mutex", &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 */ 605 { "vm object", &lock_class_mtx_sleep }, 606 { "page lock", &lock_class_mtx_sleep }, 607 { "vm page queue mutex", &lock_class_mtx_sleep }, 608 { "pmap", &lock_class_mtx_sleep }, 609 { NULL, NULL }, 610 /* 611 * kqueue/VFS interaction 612 */ 613 { "kqueue", &lock_class_mtx_sleep }, 614 { "struct mount mtx", &lock_class_mtx_sleep }, 615 { "vnode interlock", &lock_class_mtx_sleep }, 616 { NULL, NULL }, 617 /* 618 * ZFS locking 619 */ 620 { "dn->dn_mtx", &lock_class_sx }, 621 { "dr->dt.di.dr_mtx", &lock_class_sx }, 622 { "db->db_mtx", &lock_class_sx }, 623 { NULL, NULL }, 624 /* 625 * spin locks 626 */ 627 #ifdef SMP 628 { "ap boot", &lock_class_mtx_spin }, 629 #endif 630 { "rm.mutex_mtx", &lock_class_mtx_spin }, 631 { "sio", &lock_class_mtx_spin }, 632 { "scrlock", &lock_class_mtx_spin }, 633 #ifdef __i386__ 634 { "cy", &lock_class_mtx_spin }, 635 #endif 636 #ifdef __sparc64__ 637 { "pcib_mtx", &lock_class_mtx_spin }, 638 { "rtc_mtx", &lock_class_mtx_spin }, 639 #endif 640 { "scc_hwmtx", &lock_class_mtx_spin }, 641 { "uart_hwmtx", &lock_class_mtx_spin }, 642 { "fast_taskqueue", &lock_class_mtx_spin }, 643 { "intr table", &lock_class_mtx_spin }, 644 #ifdef HWPMC_HOOKS 645 { "pmc-per-proc", &lock_class_mtx_spin }, 646 #endif 647 { "process slock", &lock_class_mtx_spin }, 648 { "sleepq chain", &lock_class_mtx_spin }, 649 { "umtx lock", &lock_class_mtx_spin }, 650 { "rm_spinlock", &lock_class_mtx_spin }, 651 { "turnstile chain", &lock_class_mtx_spin }, 652 { "turnstile lock", &lock_class_mtx_spin }, 653 { "sched lock", &lock_class_mtx_spin }, 654 { "td_contested", &lock_class_mtx_spin }, 655 { "callout", &lock_class_mtx_spin }, 656 { "entropy harvest mutex", &lock_class_mtx_spin }, 657 { "syscons video lock", &lock_class_mtx_spin }, 658 #ifdef SMP 659 { "smp rendezvous", &lock_class_mtx_spin }, 660 #endif 661 #ifdef __powerpc__ 662 { "tlb0", &lock_class_mtx_spin }, 663 #endif 664 /* 665 * leaf locks 666 */ 667 { "intrcnt", &lock_class_mtx_spin }, 668 { "icu", &lock_class_mtx_spin }, 669 #if defined(SMP) && defined(__sparc64__) 670 { "ipi", &lock_class_mtx_spin }, 671 #endif 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 panic("%s: lock (%s) %s can not be recursable", __func__, 826 class->lc_name, lock->lo_name); 827 if ((lock->lo_flags & LO_SLEEPABLE) != 0 && 828 (class->lc_flags & LC_SLEEPABLE) == 0) 829 panic("%s: lock (%s) %s can not be sleepable", __func__, 830 class->lc_name, lock->lo_name); 831 if ((lock->lo_flags & LO_UPGRADABLE) != 0 && 832 (class->lc_flags & LC_UPGRADABLE) == 0) 833 panic("%s: lock (%s) %s can not be upgradable", __func__, 834 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, bump it\n", 851 __func__); 852 } else 853 lock->lo_witness = enroll(type, class); 854 } 855 856 void 857 witness_destroy(struct lock_object *lock) 858 { 859 struct lock_class *class; 860 struct witness *w; 861 862 class = LOCK_CLASS(lock); 863 864 if (witness_cold) 865 panic("lock (%s) %s destroyed while witness_cold", 866 class->lc_name, lock->lo_name); 867 868 /* XXX: need to verify that no one holds the lock */ 869 if ((lock->lo_flags & LO_WITNESS) == 0 || lock->lo_witness == NULL) 870 return; 871 w = lock->lo_witness; 872 873 mtx_lock_spin(&w_mtx); 874 MPASS(w->w_refcount > 0); 875 w->w_refcount--; 876 877 if (w->w_refcount == 0) 878 depart(w); 879 mtx_unlock_spin(&w_mtx); 880 } 881 882 #ifdef DDB 883 static void 884 witness_ddb_compute_levels(void) 885 { 886 struct witness *w; 887 888 /* 889 * First clear all levels. 890 */ 891 STAILQ_FOREACH(w, &w_all, w_list) 892 w->w_ddb_level = -1; 893 894 /* 895 * Look for locks with no parents and level all their descendants. 896 */ 897 STAILQ_FOREACH(w, &w_all, w_list) { 898 899 /* If the witness has ancestors (is not a root), skip it. */ 900 if (w->w_num_ancestors > 0) 901 continue; 902 witness_ddb_level_descendants(w, 0); 903 } 904 } 905 906 static void 907 witness_ddb_level_descendants(struct witness *w, int l) 908 { 909 int i; 910 911 if (w->w_ddb_level >= l) 912 return; 913 914 w->w_ddb_level = l; 915 l++; 916 917 for (i = 1; i <= w_max_used_index; i++) { 918 if (w_rmatrix[w->w_index][i] & WITNESS_PARENT) 919 witness_ddb_level_descendants(&w_data[i], l); 920 } 921 } 922 923 static void 924 witness_ddb_display_descendants(int(*prnt)(const char *fmt, ...), 925 struct witness *w, int indent) 926 { 927 int i; 928 929 for (i = 0; i < indent; i++) 930 prnt(" "); 931 prnt("%s (type: %s, depth: %d, active refs: %d)", 932 w->w_name, w->w_class->lc_name, 933 w->w_ddb_level, w->w_refcount); 934 if (w->w_displayed) { 935 prnt(" -- (already displayed)\n"); 936 return; 937 } 938 w->w_displayed = 1; 939 if (w->w_file != NULL && w->w_line != 0) 940 prnt(" -- last acquired @ %s:%d\n", fixup_filename(w->w_file), 941 w->w_line); 942 else 943 prnt(" -- never acquired\n"); 944 indent++; 945 WITNESS_INDEX_ASSERT(w->w_index); 946 for (i = 1; i <= w_max_used_index; i++) { 947 if (w_rmatrix[w->w_index][i] & WITNESS_PARENT) 948 witness_ddb_display_descendants(prnt, &w_data[i], 949 indent); 950 } 951 } 952 953 static void 954 witness_ddb_display_list(int(*prnt)(const char *fmt, ...), 955 struct witness_list *list) 956 { 957 struct witness *w; 958 959 STAILQ_FOREACH(w, list, w_typelist) { 960 if (w->w_file == NULL || w->w_ddb_level > 0) 961 continue; 962 963 /* This lock has no anscestors - display its descendants. */ 964 witness_ddb_display_descendants(prnt, w, 0); 965 } 966 } 967 968 static void 969 witness_ddb_display(int(*prnt)(const char *fmt, ...)) 970 { 971 struct witness *w; 972 973 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); 974 witness_ddb_compute_levels(); 975 976 /* Clear all the displayed flags. */ 977 STAILQ_FOREACH(w, &w_all, w_list) 978 w->w_displayed = 0; 979 980 /* 981 * First, handle sleep locks which have been acquired at least 982 * once. 983 */ 984 prnt("Sleep locks:\n"); 985 witness_ddb_display_list(prnt, &w_sleep); 986 987 /* 988 * Now do spin locks which have been acquired at least once. 989 */ 990 prnt("\nSpin locks:\n"); 991 witness_ddb_display_list(prnt, &w_spin); 992 993 /* 994 * Finally, any locks which have not been acquired yet. 995 */ 996 prnt("\nLocks which were never acquired:\n"); 997 STAILQ_FOREACH(w, &w_all, w_list) { 998 if (w->w_file != NULL || w->w_refcount == 0) 999 continue; 1000 prnt("%s (type: %s, depth: %d)\n", w->w_name, 1001 w->w_class->lc_name, w->w_ddb_level); 1002 } 1003 } 1004 #endif /* DDB */ 1005 1006 int 1007 witness_defineorder(struct lock_object *lock1, struct lock_object *lock2) 1008 { 1009 1010 if (witness_watch == -1 || panicstr != NULL) 1011 return (0); 1012 1013 /* Require locks that witness knows about. */ 1014 if (lock1 == NULL || lock1->lo_witness == NULL || lock2 == NULL || 1015 lock2->lo_witness == NULL) 1016 return (EINVAL); 1017 1018 mtx_assert(&w_mtx, MA_NOTOWNED); 1019 mtx_lock_spin(&w_mtx); 1020 1021 /* 1022 * If we already have either an explicit or implied lock order that 1023 * is the other way around, then return an error. 1024 */ 1025 if (witness_watch && 1026 isitmydescendant(lock2->lo_witness, lock1->lo_witness)) { 1027 mtx_unlock_spin(&w_mtx); 1028 return (EDOOFUS); 1029 } 1030 1031 /* Try to add the new order. */ 1032 CTR3(KTR_WITNESS, "%s: adding %s as a child of %s", __func__, 1033 lock2->lo_witness->w_name, lock1->lo_witness->w_name); 1034 itismychild(lock1->lo_witness, lock2->lo_witness); 1035 mtx_unlock_spin(&w_mtx); 1036 return (0); 1037 } 1038 1039 void 1040 witness_checkorder(struct lock_object *lock, int flags, const char *file, 1041 int line, struct lock_object *interlock) 1042 { 1043 struct lock_list_entry *lock_list, *lle; 1044 struct lock_instance *lock1, *lock2, *plock; 1045 struct lock_class *class; 1046 struct witness *w, *w1; 1047 struct thread *td; 1048 int i, j; 1049 1050 if (witness_cold || witness_watch < 1 || lock->lo_witness == NULL || 1051 panicstr != NULL) 1052 return; 1053 1054 w = lock->lo_witness; 1055 class = LOCK_CLASS(lock); 1056 td = curthread; 1057 1058 if (class->lc_flags & LC_SLEEPLOCK) { 1059 1060 /* 1061 * Since spin locks include a critical section, this check 1062 * implicitly enforces a lock order of all sleep locks before 1063 * all spin locks. 1064 */ 1065 if (td->td_critnest != 0 && !kdb_active) 1066 panic("blockable sleep lock (%s) %s @ %s:%d", 1067 class->lc_name, lock->lo_name, 1068 fixup_filename(file), line); 1069 1070 /* 1071 * If this is the first lock acquired then just return as 1072 * no order checking is needed. 1073 */ 1074 lock_list = td->td_sleeplocks; 1075 if (lock_list == NULL || lock_list->ll_count == 0) 1076 return; 1077 } else { 1078 1079 /* 1080 * If this is the first lock, just return as no order 1081 * checking is needed. Avoid problems with thread 1082 * migration pinning the thread while checking if 1083 * spinlocks are held. If at least one spinlock is held 1084 * the thread is in a safe path and it is allowed to 1085 * unpin it. 1086 */ 1087 sched_pin(); 1088 lock_list = PCPU_GET(spinlocks); 1089 if (lock_list == NULL || lock_list->ll_count == 0) { 1090 sched_unpin(); 1091 return; 1092 } 1093 sched_unpin(); 1094 } 1095 1096 /* 1097 * Check to see if we are recursing on a lock we already own. If 1098 * so, make sure that we don't mismatch exclusive and shared lock 1099 * acquires. 1100 */ 1101 lock1 = find_instance(lock_list, lock); 1102 if (lock1 != NULL) { 1103 if ((lock1->li_flags & LI_EXCLUSIVE) != 0 && 1104 (flags & LOP_EXCLUSIVE) == 0) { 1105 printf("shared lock of (%s) %s @ %s:%d\n", 1106 class->lc_name, lock->lo_name, 1107 fixup_filename(file), line); 1108 printf("while exclusively locked from %s:%d\n", 1109 fixup_filename(lock1->li_file), lock1->li_line); 1110 panic("share->excl"); 1111 } 1112 if ((lock1->li_flags & LI_EXCLUSIVE) == 0 && 1113 (flags & LOP_EXCLUSIVE) != 0) { 1114 printf("exclusive lock of (%s) %s @ %s:%d\n", 1115 class->lc_name, lock->lo_name, 1116 fixup_filename(file), line); 1117 printf("while share locked from %s:%d\n", 1118 fixup_filename(lock1->li_file), lock1->li_line); 1119 panic("excl->share"); 1120 } 1121 return; 1122 } 1123 1124 /* 1125 * Find the previously acquired lock, but ignore interlocks. 1126 */ 1127 plock = &lock_list->ll_children[lock_list->ll_count - 1]; 1128 if (interlock != NULL && plock->li_lock == interlock) { 1129 if (lock_list->ll_count > 1) 1130 plock = 1131 &lock_list->ll_children[lock_list->ll_count - 2]; 1132 else { 1133 lle = lock_list->ll_next; 1134 1135 /* 1136 * The interlock is the only lock we hold, so 1137 * simply return. 1138 */ 1139 if (lle == NULL) 1140 return; 1141 plock = &lle->ll_children[lle->ll_count - 1]; 1142 } 1143 } 1144 1145 /* 1146 * Try to perform most checks without a lock. If this succeeds we 1147 * can skip acquiring the lock and return success. 1148 */ 1149 w1 = plock->li_lock->lo_witness; 1150 if (witness_lock_order_check(w1, w)) 1151 return; 1152 1153 /* 1154 * Check for duplicate locks of the same type. Note that we only 1155 * have to check for this on the last lock we just acquired. Any 1156 * other cases will be caught as lock order violations. 1157 */ 1158 mtx_lock_spin(&w_mtx); 1159 witness_lock_order_add(w1, w); 1160 if (w1 == w) { 1161 i = w->w_index; 1162 if (!(lock->lo_flags & LO_DUPOK) && !(flags & LOP_DUPOK) && 1163 !(w_rmatrix[i][i] & WITNESS_REVERSAL)) { 1164 w_rmatrix[i][i] |= WITNESS_REVERSAL; 1165 w->w_reversed = 1; 1166 mtx_unlock_spin(&w_mtx); 1167 printf( 1168 "acquiring duplicate lock of same type: \"%s\"\n", 1169 w->w_name); 1170 printf(" 1st %s @ %s:%d\n", plock->li_lock->lo_name, 1171 fixup_filename(plock->li_file), plock->li_line); 1172 printf(" 2nd %s @ %s:%d\n", lock->lo_name, 1173 fixup_filename(file), line); 1174 witness_debugger(1); 1175 } else 1176 mtx_unlock_spin(&w_mtx); 1177 return; 1178 } 1179 mtx_assert(&w_mtx, MA_OWNED); 1180 1181 /* 1182 * If we know that the lock we are acquiring comes after 1183 * the lock we most recently acquired in the lock order tree, 1184 * then there is no need for any further checks. 1185 */ 1186 if (isitmychild(w1, w)) 1187 goto out; 1188 1189 for (j = 0, lle = lock_list; lle != NULL; lle = lle->ll_next) { 1190 for (i = lle->ll_count - 1; i >= 0; i--, j++) { 1191 1192 MPASS(j < WITNESS_COUNT); 1193 lock1 = &lle->ll_children[i]; 1194 1195 /* 1196 * Ignore the interlock the first time we see it. 1197 */ 1198 if (interlock != NULL && interlock == lock1->li_lock) { 1199 interlock = NULL; 1200 continue; 1201 } 1202 1203 /* 1204 * If this lock doesn't undergo witness checking, 1205 * then skip it. 1206 */ 1207 w1 = lock1->li_lock->lo_witness; 1208 if (w1 == NULL) { 1209 KASSERT((lock1->li_lock->lo_flags & LO_WITNESS) == 0, 1210 ("lock missing witness structure")); 1211 continue; 1212 } 1213 1214 /* 1215 * If we are locking Giant and this is a sleepable 1216 * lock, then skip it. 1217 */ 1218 if ((lock1->li_lock->lo_flags & LO_SLEEPABLE) != 0 && 1219 lock == &Giant.lock_object) 1220 continue; 1221 1222 /* 1223 * If we are locking a sleepable lock and this lock 1224 * is Giant, then skip it. 1225 */ 1226 if ((lock->lo_flags & LO_SLEEPABLE) != 0 && 1227 lock1->li_lock == &Giant.lock_object) 1228 continue; 1229 1230 /* 1231 * If we are locking a sleepable lock and this lock 1232 * isn't sleepable, we want to treat it as a lock 1233 * order violation to enfore a general lock order of 1234 * sleepable locks before non-sleepable locks. 1235 */ 1236 if (((lock->lo_flags & LO_SLEEPABLE) != 0 && 1237 (lock1->li_lock->lo_flags & LO_SLEEPABLE) == 0)) 1238 goto reversal; 1239 1240 /* 1241 * If we are locking Giant and this is a non-sleepable 1242 * lock, then treat it as a reversal. 1243 */ 1244 if ((lock1->li_lock->lo_flags & LO_SLEEPABLE) == 0 && 1245 lock == &Giant.lock_object) 1246 goto reversal; 1247 1248 /* 1249 * Check the lock order hierarchy for a reveresal. 1250 */ 1251 if (!isitmydescendant(w, w1)) 1252 continue; 1253 reversal: 1254 1255 /* 1256 * We have a lock order violation, check to see if it 1257 * is allowed or has already been yelled about. 1258 */ 1259 #ifdef BLESSING 1260 1261 /* 1262 * If the lock order is blessed, just bail. We don't 1263 * look for other lock order violations though, which 1264 * may be a bug. 1265 */ 1266 if (blessed(w, w1)) 1267 goto out; 1268 #endif 1269 1270 /* Bail if this violation is known */ 1271 if (w_rmatrix[w1->w_index][w->w_index] & WITNESS_REVERSAL) 1272 goto out; 1273 1274 /* Record this as a violation */ 1275 w_rmatrix[w1->w_index][w->w_index] |= WITNESS_REVERSAL; 1276 w_rmatrix[w->w_index][w1->w_index] |= WITNESS_REVERSAL; 1277 w->w_reversed = w1->w_reversed = 1; 1278 witness_increment_graph_generation(); 1279 mtx_unlock_spin(&w_mtx); 1280 1281 /* 1282 * Ok, yell about it. 1283 */ 1284 if (((lock->lo_flags & LO_SLEEPABLE) != 0 && 1285 (lock1->li_lock->lo_flags & LO_SLEEPABLE) == 0)) 1286 printf( 1287 "lock order reversal: (sleepable after non-sleepable)\n"); 1288 else if ((lock1->li_lock->lo_flags & LO_SLEEPABLE) == 0 1289 && lock == &Giant.lock_object) 1290 printf( 1291 "lock order reversal: (Giant after non-sleepable)\n"); 1292 else 1293 printf("lock order reversal:\n"); 1294 1295 /* 1296 * Try to locate an earlier lock with 1297 * witness w in our list. 1298 */ 1299 do { 1300 lock2 = &lle->ll_children[i]; 1301 MPASS(lock2->li_lock != NULL); 1302 if (lock2->li_lock->lo_witness == w) 1303 break; 1304 if (i == 0 && lle->ll_next != NULL) { 1305 lle = lle->ll_next; 1306 i = lle->ll_count - 1; 1307 MPASS(i >= 0 && i < LOCK_NCHILDREN); 1308 } else 1309 i--; 1310 } while (i >= 0); 1311 if (i < 0) { 1312 printf(" 1st %p %s (%s) @ %s:%d\n", 1313 lock1->li_lock, lock1->li_lock->lo_name, 1314 w1->w_name, fixup_filename(lock1->li_file), 1315 lock1->li_line); 1316 printf(" 2nd %p %s (%s) @ %s:%d\n", lock, 1317 lock->lo_name, w->w_name, 1318 fixup_filename(file), line); 1319 } else { 1320 printf(" 1st %p %s (%s) @ %s:%d\n", 1321 lock2->li_lock, lock2->li_lock->lo_name, 1322 lock2->li_lock->lo_witness->w_name, 1323 fixup_filename(lock2->li_file), 1324 lock2->li_line); 1325 printf(" 2nd %p %s (%s) @ %s:%d\n", 1326 lock1->li_lock, lock1->li_lock->lo_name, 1327 w1->w_name, fixup_filename(lock1->li_file), 1328 lock1->li_line); 1329 printf(" 3rd %p %s (%s) @ %s:%d\n", lock, 1330 lock->lo_name, w->w_name, 1331 fixup_filename(file), line); 1332 } 1333 witness_debugger(1); 1334 return; 1335 } 1336 } 1337 1338 /* 1339 * If requested, build a new lock order. However, don't build a new 1340 * relationship between a sleepable lock and Giant if it is in the 1341 * wrong direction. The correct lock order is that sleepable locks 1342 * always come before Giant. 1343 */ 1344 if (flags & LOP_NEWORDER && 1345 !(plock->li_lock == &Giant.lock_object && 1346 (lock->lo_flags & LO_SLEEPABLE) != 0)) { 1347 CTR3(KTR_WITNESS, "%s: adding %s as a child of %s", __func__, 1348 w->w_name, plock->li_lock->lo_witness->w_name); 1349 itismychild(plock->li_lock->lo_witness, w); 1350 } 1351 out: 1352 mtx_unlock_spin(&w_mtx); 1353 } 1354 1355 void 1356 witness_lock(struct lock_object *lock, int flags, const char *file, int line) 1357 { 1358 struct lock_list_entry **lock_list, *lle; 1359 struct lock_instance *instance; 1360 struct witness *w; 1361 struct thread *td; 1362 1363 if (witness_cold || witness_watch == -1 || lock->lo_witness == NULL || 1364 panicstr != NULL) 1365 return; 1366 w = lock->lo_witness; 1367 td = curthread; 1368 1369 /* Determine lock list for this lock. */ 1370 if (LOCK_CLASS(lock)->lc_flags & LC_SLEEPLOCK) 1371 lock_list = &td->td_sleeplocks; 1372 else 1373 lock_list = PCPU_PTR(spinlocks); 1374 1375 /* Check to see if we are recursing on a lock we already own. */ 1376 instance = find_instance(*lock_list, lock); 1377 if (instance != NULL) { 1378 instance->li_flags++; 1379 CTR4(KTR_WITNESS, "%s: pid %d recursed on %s r=%d", __func__, 1380 td->td_proc->p_pid, lock->lo_name, 1381 instance->li_flags & LI_RECURSEMASK); 1382 instance->li_file = file; 1383 instance->li_line = line; 1384 return; 1385 } 1386 1387 /* Update per-witness last file and line acquire. */ 1388 w->w_file = file; 1389 w->w_line = line; 1390 1391 /* Find the next open lock instance in the list and fill it. */ 1392 lle = *lock_list; 1393 if (lle == NULL || lle->ll_count == LOCK_NCHILDREN) { 1394 lle = witness_lock_list_get(); 1395 if (lle == NULL) 1396 return; 1397 lle->ll_next = *lock_list; 1398 CTR3(KTR_WITNESS, "%s: pid %d added lle %p", __func__, 1399 td->td_proc->p_pid, lle); 1400 *lock_list = lle; 1401 } 1402 instance = &lle->ll_children[lle->ll_count++]; 1403 instance->li_lock = lock; 1404 instance->li_line = line; 1405 instance->li_file = file; 1406 if ((flags & LOP_EXCLUSIVE) != 0) 1407 instance->li_flags = LI_EXCLUSIVE; 1408 else 1409 instance->li_flags = 0; 1410 CTR4(KTR_WITNESS, "%s: pid %d added %s as lle[%d]", __func__, 1411 td->td_proc->p_pid, lock->lo_name, lle->ll_count - 1); 1412 } 1413 1414 void 1415 witness_upgrade(struct lock_object *lock, int flags, const char *file, int line) 1416 { 1417 struct lock_instance *instance; 1418 struct lock_class *class; 1419 1420 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); 1421 if (lock->lo_witness == NULL || witness_watch == -1 || panicstr != NULL) 1422 return; 1423 class = LOCK_CLASS(lock); 1424 if (witness_watch) { 1425 if ((lock->lo_flags & LO_UPGRADABLE) == 0) 1426 panic("upgrade of non-upgradable lock (%s) %s @ %s:%d", 1427 class->lc_name, lock->lo_name, 1428 fixup_filename(file), line); 1429 if ((class->lc_flags & LC_SLEEPLOCK) == 0) 1430 panic("upgrade of non-sleep lock (%s) %s @ %s:%d", 1431 class->lc_name, lock->lo_name, 1432 fixup_filename(file), line); 1433 } 1434 instance = find_instance(curthread->td_sleeplocks, lock); 1435 if (instance == NULL) 1436 panic("upgrade of unlocked lock (%s) %s @ %s:%d", 1437 class->lc_name, lock->lo_name, 1438 fixup_filename(file), line); 1439 if (witness_watch) { 1440 if ((instance->li_flags & LI_EXCLUSIVE) != 0) 1441 panic("upgrade of exclusive lock (%s) %s @ %s:%d", 1442 class->lc_name, lock->lo_name, 1443 fixup_filename(file), line); 1444 if ((instance->li_flags & LI_RECURSEMASK) != 0) 1445 panic("upgrade of recursed lock (%s) %s r=%d @ %s:%d", 1446 class->lc_name, lock->lo_name, 1447 instance->li_flags & LI_RECURSEMASK, 1448 fixup_filename(file), line); 1449 } 1450 instance->li_flags |= LI_EXCLUSIVE; 1451 } 1452 1453 void 1454 witness_downgrade(struct lock_object *lock, int flags, const char *file, 1455 int line) 1456 { 1457 struct lock_instance *instance; 1458 struct lock_class *class; 1459 1460 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); 1461 if (lock->lo_witness == NULL || witness_watch == -1 || panicstr != NULL) 1462 return; 1463 class = LOCK_CLASS(lock); 1464 if (witness_watch) { 1465 if ((lock->lo_flags & LO_UPGRADABLE) == 0) 1466 panic("downgrade of non-upgradable lock (%s) %s @ %s:%d", 1467 class->lc_name, lock->lo_name, 1468 fixup_filename(file), line); 1469 if ((class->lc_flags & LC_SLEEPLOCK) == 0) 1470 panic("downgrade of non-sleep lock (%s) %s @ %s:%d", 1471 class->lc_name, lock->lo_name, 1472 fixup_filename(file), line); 1473 } 1474 instance = find_instance(curthread->td_sleeplocks, lock); 1475 if (instance == NULL) 1476 panic("downgrade of unlocked lock (%s) %s @ %s:%d", 1477 class->lc_name, lock->lo_name, 1478 fixup_filename(file), line); 1479 if (witness_watch) { 1480 if ((instance->li_flags & LI_EXCLUSIVE) == 0) 1481 panic("downgrade of shared lock (%s) %s @ %s:%d", 1482 class->lc_name, lock->lo_name, 1483 fixup_filename(file), line); 1484 if ((instance->li_flags & LI_RECURSEMASK) != 0) 1485 panic("downgrade of recursed lock (%s) %s r=%d @ %s:%d", 1486 class->lc_name, lock->lo_name, 1487 instance->li_flags & LI_RECURSEMASK, 1488 fixup_filename(file), line); 1489 } 1490 instance->li_flags &= ~LI_EXCLUSIVE; 1491 } 1492 1493 void 1494 witness_unlock(struct lock_object *lock, int flags, const char *file, int line) 1495 { 1496 struct lock_list_entry **lock_list, *lle; 1497 struct lock_instance *instance; 1498 struct lock_class *class; 1499 struct thread *td; 1500 register_t s; 1501 int i, j; 1502 1503 if (witness_cold || lock->lo_witness == NULL || panicstr != NULL) 1504 return; 1505 td = curthread; 1506 class = LOCK_CLASS(lock); 1507 1508 /* Find lock instance associated with this lock. */ 1509 if (class->lc_flags & LC_SLEEPLOCK) 1510 lock_list = &td->td_sleeplocks; 1511 else 1512 lock_list = PCPU_PTR(spinlocks); 1513 lle = *lock_list; 1514 for (; *lock_list != NULL; lock_list = &(*lock_list)->ll_next) 1515 for (i = 0; i < (*lock_list)->ll_count; i++) { 1516 instance = &(*lock_list)->ll_children[i]; 1517 if (instance->li_lock == lock) 1518 goto found; 1519 } 1520 1521 /* 1522 * When disabling WITNESS through witness_watch we could end up in 1523 * having registered locks in the td_sleeplocks queue. 1524 * We have to make sure we flush these queues, so just search for 1525 * eventual register locks and remove them. 1526 */ 1527 if (witness_watch > 0) 1528 panic("lock (%s) %s not locked @ %s:%d", class->lc_name, 1529 lock->lo_name, fixup_filename(file), line); 1530 else 1531 return; 1532 found: 1533 1534 /* First, check for shared/exclusive mismatches. */ 1535 if ((instance->li_flags & LI_EXCLUSIVE) != 0 && witness_watch > 0 && 1536 (flags & LOP_EXCLUSIVE) == 0) { 1537 printf("shared unlock of (%s) %s @ %s:%d\n", class->lc_name, 1538 lock->lo_name, fixup_filename(file), line); 1539 printf("while exclusively locked from %s:%d\n", 1540 fixup_filename(instance->li_file), instance->li_line); 1541 panic("excl->ushare"); 1542 } 1543 if ((instance->li_flags & LI_EXCLUSIVE) == 0 && witness_watch > 0 && 1544 (flags & LOP_EXCLUSIVE) != 0) { 1545 printf("exclusive unlock of (%s) %s @ %s:%d\n", class->lc_name, 1546 lock->lo_name, fixup_filename(file), line); 1547 printf("while share locked from %s:%d\n", 1548 fixup_filename(instance->li_file), 1549 instance->li_line); 1550 panic("share->uexcl"); 1551 } 1552 /* If we are recursed, unrecurse. */ 1553 if ((instance->li_flags & LI_RECURSEMASK) > 0) { 1554 CTR4(KTR_WITNESS, "%s: pid %d unrecursed on %s r=%d", __func__, 1555 td->td_proc->p_pid, instance->li_lock->lo_name, 1556 instance->li_flags); 1557 instance->li_flags--; 1558 return; 1559 } 1560 /* The lock is now being dropped, check for NORELEASE flag */ 1561 if ((instance->li_flags & LI_NORELEASE) != 0 && witness_watch > 0) { 1562 printf("forbidden unlock of (%s) %s @ %s:%d\n", class->lc_name, 1563 lock->lo_name, fixup_filename(file), line); 1564 panic("lock marked norelease"); 1565 } 1566 1567 /* Otherwise, remove this item from the list. */ 1568 s = intr_disable(); 1569 CTR4(KTR_WITNESS, "%s: pid %d removed %s from lle[%d]", __func__, 1570 td->td_proc->p_pid, instance->li_lock->lo_name, 1571 (*lock_list)->ll_count - 1); 1572 for (j = i; j < (*lock_list)->ll_count - 1; j++) 1573 (*lock_list)->ll_children[j] = 1574 (*lock_list)->ll_children[j + 1]; 1575 (*lock_list)->ll_count--; 1576 intr_restore(s); 1577 1578 /* 1579 * In order to reduce contention on w_mtx, we want to keep always an 1580 * head object into lists so that frequent allocation from the 1581 * free witness pool (and subsequent locking) is avoided. 1582 * In order to maintain the current code simple, when the head 1583 * object is totally unloaded it means also that we do not have 1584 * further objects in the list, so the list ownership needs to be 1585 * hand over to another object if the current head needs to be freed. 1586 */ 1587 if ((*lock_list)->ll_count == 0) { 1588 if (*lock_list == lle) { 1589 if (lle->ll_next == NULL) 1590 return; 1591 } else 1592 lle = *lock_list; 1593 *lock_list = lle->ll_next; 1594 CTR3(KTR_WITNESS, "%s: pid %d removed lle %p", __func__, 1595 td->td_proc->p_pid, lle); 1596 witness_lock_list_free(lle); 1597 } 1598 } 1599 1600 void 1601 witness_thread_exit(struct thread *td) 1602 { 1603 struct lock_list_entry *lle; 1604 int i, n; 1605 1606 lle = td->td_sleeplocks; 1607 if (lle == NULL || panicstr != NULL) 1608 return; 1609 if (lle->ll_count != 0) { 1610 for (n = 0; lle != NULL; lle = lle->ll_next) 1611 for (i = lle->ll_count - 1; i >= 0; i--) { 1612 if (n == 0) 1613 printf("Thread %p exiting with the following locks held:\n", 1614 td); 1615 n++; 1616 witness_list_lock(&lle->ll_children[i], printf); 1617 1618 } 1619 panic("Thread %p cannot exit while holding sleeplocks\n", td); 1620 } 1621 witness_lock_list_free(lle); 1622 } 1623 1624 /* 1625 * Warn if any locks other than 'lock' are held. Flags can be passed in to 1626 * exempt Giant and sleepable locks from the checks as well. If any 1627 * non-exempt locks are held, then a supplied message is printed to the 1628 * console along with a list of the offending locks. If indicated in the 1629 * flags then a failure results in a panic as well. 1630 */ 1631 int 1632 witness_warn(int flags, struct lock_object *lock, const char *fmt, ...) 1633 { 1634 struct lock_list_entry *lock_list, *lle; 1635 struct lock_instance *lock1; 1636 struct thread *td; 1637 va_list ap; 1638 int i, n; 1639 1640 if (witness_cold || witness_watch < 1 || panicstr != NULL) 1641 return (0); 1642 n = 0; 1643 td = curthread; 1644 for (lle = td->td_sleeplocks; lle != NULL; lle = lle->ll_next) 1645 for (i = lle->ll_count - 1; i >= 0; i--) { 1646 lock1 = &lle->ll_children[i]; 1647 if (lock1->li_lock == lock) 1648 continue; 1649 if (flags & WARN_GIANTOK && 1650 lock1->li_lock == &Giant.lock_object) 1651 continue; 1652 if (flags & WARN_SLEEPOK && 1653 (lock1->li_lock->lo_flags & LO_SLEEPABLE) != 0) 1654 continue; 1655 if (n == 0) { 1656 va_start(ap, fmt); 1657 vprintf(fmt, ap); 1658 va_end(ap); 1659 printf(" with the following"); 1660 if (flags & WARN_SLEEPOK) 1661 printf(" non-sleepable"); 1662 printf(" locks held:\n"); 1663 } 1664 n++; 1665 witness_list_lock(lock1, printf); 1666 } 1667 1668 /* 1669 * Pin the thread in order to avoid problems with thread migration. 1670 * Once that all verifies are passed about spinlocks ownership, 1671 * the thread is in a safe path and it can be unpinned. 1672 */ 1673 sched_pin(); 1674 lock_list = PCPU_GET(spinlocks); 1675 if (lock_list != NULL && lock_list->ll_count != 0) { 1676 sched_unpin(); 1677 1678 /* 1679 * We should only have one spinlock and as long as 1680 * the flags cannot match for this locks class, 1681 * check if the first spinlock is the one curthread 1682 * should hold. 1683 */ 1684 lock1 = &lock_list->ll_children[lock_list->ll_count - 1]; 1685 if (lock_list->ll_count == 1 && lock_list->ll_next == NULL && 1686 lock1->li_lock == lock && n == 0) 1687 return (0); 1688 1689 va_start(ap, fmt); 1690 vprintf(fmt, ap); 1691 va_end(ap); 1692 printf(" with the following"); 1693 if (flags & WARN_SLEEPOK) 1694 printf(" non-sleepable"); 1695 printf(" locks held:\n"); 1696 n += witness_list_locks(&lock_list, printf); 1697 } else 1698 sched_unpin(); 1699 if (flags & WARN_PANIC && n) 1700 panic("%s", __func__); 1701 else 1702 witness_debugger(n); 1703 return (n); 1704 } 1705 1706 const char * 1707 witness_file(struct lock_object *lock) 1708 { 1709 struct witness *w; 1710 1711 if (witness_cold || witness_watch < 1 || lock->lo_witness == NULL) 1712 return ("?"); 1713 w = lock->lo_witness; 1714 return (w->w_file); 1715 } 1716 1717 int 1718 witness_line(struct lock_object *lock) 1719 { 1720 struct witness *w; 1721 1722 if (witness_cold || witness_watch < 1 || lock->lo_witness == NULL) 1723 return (0); 1724 w = lock->lo_witness; 1725 return (w->w_line); 1726 } 1727 1728 static struct witness * 1729 enroll(const char *description, struct lock_class *lock_class) 1730 { 1731 struct witness *w; 1732 struct witness_list *typelist; 1733 1734 MPASS(description != NULL); 1735 1736 if (witness_watch == -1 || panicstr != NULL) 1737 return (NULL); 1738 if ((lock_class->lc_flags & LC_SPINLOCK)) { 1739 if (witness_skipspin) 1740 return (NULL); 1741 else 1742 typelist = &w_spin; 1743 } else if ((lock_class->lc_flags & LC_SLEEPLOCK)) 1744 typelist = &w_sleep; 1745 else 1746 panic("lock class %s is not sleep or spin", 1747 lock_class->lc_name); 1748 1749 mtx_lock_spin(&w_mtx); 1750 w = witness_hash_get(description); 1751 if (w) 1752 goto found; 1753 if ((w = witness_get()) == NULL) 1754 return (NULL); 1755 MPASS(strlen(description) < MAX_W_NAME); 1756 strcpy(w->w_name, description); 1757 w->w_class = lock_class; 1758 w->w_refcount = 1; 1759 STAILQ_INSERT_HEAD(&w_all, w, w_list); 1760 if (lock_class->lc_flags & LC_SPINLOCK) { 1761 STAILQ_INSERT_HEAD(&w_spin, w, w_typelist); 1762 w_spin_cnt++; 1763 } else if (lock_class->lc_flags & LC_SLEEPLOCK) { 1764 STAILQ_INSERT_HEAD(&w_sleep, w, w_typelist); 1765 w_sleep_cnt++; 1766 } 1767 1768 /* Insert new witness into the hash */ 1769 witness_hash_put(w); 1770 witness_increment_graph_generation(); 1771 mtx_unlock_spin(&w_mtx); 1772 return (w); 1773 found: 1774 w->w_refcount++; 1775 mtx_unlock_spin(&w_mtx); 1776 if (lock_class != w->w_class) 1777 panic( 1778 "lock (%s) %s does not match earlier (%s) lock", 1779 description, lock_class->lc_name, 1780 w->w_class->lc_name); 1781 return (w); 1782 } 1783 1784 static void 1785 depart(struct witness *w) 1786 { 1787 struct witness_list *list; 1788 1789 MPASS(w->w_refcount == 0); 1790 if (w->w_class->lc_flags & LC_SLEEPLOCK) { 1791 list = &w_sleep; 1792 w_sleep_cnt--; 1793 } else { 1794 list = &w_spin; 1795 w_spin_cnt--; 1796 } 1797 /* 1798 * Set file to NULL as it may point into a loadable module. 1799 */ 1800 w->w_file = NULL; 1801 w->w_line = 0; 1802 witness_increment_graph_generation(); 1803 } 1804 1805 1806 static void 1807 adopt(struct witness *parent, struct witness *child) 1808 { 1809 int pi, ci, i, j; 1810 1811 if (witness_cold == 0) 1812 mtx_assert(&w_mtx, MA_OWNED); 1813 1814 /* If the relationship is already known, there's no work to be done. */ 1815 if (isitmychild(parent, child)) 1816 return; 1817 1818 /* When the structure of the graph changes, bump up the generation. */ 1819 witness_increment_graph_generation(); 1820 1821 /* 1822 * The hard part ... create the direct relationship, then propagate all 1823 * indirect relationships. 1824 */ 1825 pi = parent->w_index; 1826 ci = child->w_index; 1827 WITNESS_INDEX_ASSERT(pi); 1828 WITNESS_INDEX_ASSERT(ci); 1829 MPASS(pi != ci); 1830 w_rmatrix[pi][ci] |= WITNESS_PARENT; 1831 w_rmatrix[ci][pi] |= WITNESS_CHILD; 1832 1833 /* 1834 * If parent was not already an ancestor of child, 1835 * then we increment the descendant and ancestor counters. 1836 */ 1837 if ((w_rmatrix[pi][ci] & WITNESS_ANCESTOR) == 0) { 1838 parent->w_num_descendants++; 1839 child->w_num_ancestors++; 1840 } 1841 1842 /* 1843 * Find each ancestor of 'pi'. Note that 'pi' itself is counted as 1844 * an ancestor of 'pi' during this loop. 1845 */ 1846 for (i = 1; i <= w_max_used_index; i++) { 1847 if ((w_rmatrix[i][pi] & WITNESS_ANCESTOR_MASK) == 0 && 1848 (i != pi)) 1849 continue; 1850 1851 /* Find each descendant of 'i' and mark it as a descendant. */ 1852 for (j = 1; j <= w_max_used_index; j++) { 1853 1854 /* 1855 * Skip children that are already marked as 1856 * descendants of 'i'. 1857 */ 1858 if (w_rmatrix[i][j] & WITNESS_ANCESTOR_MASK) 1859 continue; 1860 1861 /* 1862 * We are only interested in descendants of 'ci'. Note 1863 * that 'ci' itself is counted as a descendant of 'ci'. 1864 */ 1865 if ((w_rmatrix[ci][j] & WITNESS_ANCESTOR_MASK) == 0 && 1866 (j != ci)) 1867 continue; 1868 w_rmatrix[i][j] |= WITNESS_ANCESTOR; 1869 w_rmatrix[j][i] |= WITNESS_DESCENDANT; 1870 w_data[i].w_num_descendants++; 1871 w_data[j].w_num_ancestors++; 1872 1873 /* 1874 * Make sure we aren't marking a node as both an 1875 * ancestor and descendant. We should have caught 1876 * this as a lock order reversal earlier. 1877 */ 1878 if ((w_rmatrix[i][j] & WITNESS_ANCESTOR_MASK) && 1879 (w_rmatrix[i][j] & WITNESS_DESCENDANT_MASK)) { 1880 printf("witness rmatrix paradox! [%d][%d]=%d " 1881 "both ancestor and descendant\n", 1882 i, j, w_rmatrix[i][j]); 1883 kdb_backtrace(); 1884 printf("Witness disabled.\n"); 1885 witness_watch = -1; 1886 } 1887 if ((w_rmatrix[j][i] & WITNESS_ANCESTOR_MASK) && 1888 (w_rmatrix[j][i] & WITNESS_DESCENDANT_MASK)) { 1889 printf("witness rmatrix paradox! [%d][%d]=%d " 1890 "both ancestor and descendant\n", 1891 j, i, w_rmatrix[j][i]); 1892 kdb_backtrace(); 1893 printf("Witness disabled.\n"); 1894 witness_watch = -1; 1895 } 1896 } 1897 } 1898 } 1899 1900 static void 1901 itismychild(struct witness *parent, struct witness *child) 1902 { 1903 1904 MPASS(child != NULL && parent != NULL); 1905 if (witness_cold == 0) 1906 mtx_assert(&w_mtx, MA_OWNED); 1907 1908 if (!witness_lock_type_equal(parent, child)) { 1909 if (witness_cold == 0) 1910 mtx_unlock_spin(&w_mtx); 1911 panic("%s: parent \"%s\" (%s) and child \"%s\" (%s) are not " 1912 "the same lock type", __func__, parent->w_name, 1913 parent->w_class->lc_name, child->w_name, 1914 child->w_class->lc_name); 1915 } 1916 adopt(parent, child); 1917 } 1918 1919 /* 1920 * Generic code for the isitmy*() functions. The rmask parameter is the 1921 * expected relationship of w1 to w2. 1922 */ 1923 static int 1924 _isitmyx(struct witness *w1, struct witness *w2, int rmask, const char *fname) 1925 { 1926 unsigned char r1, r2; 1927 int i1, i2; 1928 1929 i1 = w1->w_index; 1930 i2 = w2->w_index; 1931 WITNESS_INDEX_ASSERT(i1); 1932 WITNESS_INDEX_ASSERT(i2); 1933 r1 = w_rmatrix[i1][i2] & WITNESS_RELATED_MASK; 1934 r2 = w_rmatrix[i2][i1] & WITNESS_RELATED_MASK; 1935 1936 /* The flags on one better be the inverse of the flags on the other */ 1937 if (!((WITNESS_ATOD(r1) == r2 && WITNESS_DTOA(r2) == r1) || 1938 (WITNESS_DTOA(r1) == r2 && WITNESS_ATOD(r2) == r1))) { 1939 printf("%s: rmatrix mismatch between %s (index %d) and %s " 1940 "(index %d): w_rmatrix[%d][%d] == %hhx but " 1941 "w_rmatrix[%d][%d] == %hhx\n", 1942 fname, w1->w_name, i1, w2->w_name, i2, i1, i2, r1, 1943 i2, i1, r2); 1944 kdb_backtrace(); 1945 printf("Witness disabled.\n"); 1946 witness_watch = -1; 1947 } 1948 return (r1 & rmask); 1949 } 1950 1951 /* 1952 * Checks if @child is a direct child of @parent. 1953 */ 1954 static int 1955 isitmychild(struct witness *parent, struct witness *child) 1956 { 1957 1958 return (_isitmyx(parent, child, WITNESS_PARENT, __func__)); 1959 } 1960 1961 /* 1962 * Checks if @descendant is a direct or inderect descendant of @ancestor. 1963 */ 1964 static int 1965 isitmydescendant(struct witness *ancestor, struct witness *descendant) 1966 { 1967 1968 return (_isitmyx(ancestor, descendant, WITNESS_ANCESTOR_MASK, 1969 __func__)); 1970 } 1971 1972 #ifdef BLESSING 1973 static int 1974 blessed(struct witness *w1, struct witness *w2) 1975 { 1976 int i; 1977 struct witness_blessed *b; 1978 1979 for (i = 0; i < blessed_count; i++) { 1980 b = &blessed_list[i]; 1981 if (strcmp(w1->w_name, b->b_lock1) == 0) { 1982 if (strcmp(w2->w_name, b->b_lock2) == 0) 1983 return (1); 1984 continue; 1985 } 1986 if (strcmp(w1->w_name, b->b_lock2) == 0) 1987 if (strcmp(w2->w_name, b->b_lock1) == 0) 1988 return (1); 1989 } 1990 return (0); 1991 } 1992 #endif 1993 1994 static struct witness * 1995 witness_get(void) 1996 { 1997 struct witness *w; 1998 int index; 1999 2000 if (witness_cold == 0) 2001 mtx_assert(&w_mtx, MA_OWNED); 2002 2003 if (witness_watch == -1) { 2004 mtx_unlock_spin(&w_mtx); 2005 return (NULL); 2006 } 2007 if (STAILQ_EMPTY(&w_free)) { 2008 witness_watch = -1; 2009 mtx_unlock_spin(&w_mtx); 2010 printf("WITNESS: unable to allocate a new witness object\n"); 2011 return (NULL); 2012 } 2013 w = STAILQ_FIRST(&w_free); 2014 STAILQ_REMOVE_HEAD(&w_free, w_list); 2015 w_free_cnt--; 2016 index = w->w_index; 2017 MPASS(index > 0 && index == w_max_used_index+1 && 2018 index < WITNESS_COUNT); 2019 bzero(w, sizeof(*w)); 2020 w->w_index = index; 2021 if (index > w_max_used_index) 2022 w_max_used_index = index; 2023 return (w); 2024 } 2025 2026 static void 2027 witness_free(struct witness *w) 2028 { 2029 2030 STAILQ_INSERT_HEAD(&w_free, w, w_list); 2031 w_free_cnt++; 2032 } 2033 2034 static struct lock_list_entry * 2035 witness_lock_list_get(void) 2036 { 2037 struct lock_list_entry *lle; 2038 2039 if (witness_watch == -1) 2040 return (NULL); 2041 mtx_lock_spin(&w_mtx); 2042 lle = w_lock_list_free; 2043 if (lle == NULL) { 2044 witness_watch = -1; 2045 mtx_unlock_spin(&w_mtx); 2046 printf("%s: witness exhausted\n", __func__); 2047 return (NULL); 2048 } 2049 w_lock_list_free = lle->ll_next; 2050 mtx_unlock_spin(&w_mtx); 2051 bzero(lle, sizeof(*lle)); 2052 return (lle); 2053 } 2054 2055 static void 2056 witness_lock_list_free(struct lock_list_entry *lle) 2057 { 2058 2059 mtx_lock_spin(&w_mtx); 2060 lle->ll_next = w_lock_list_free; 2061 w_lock_list_free = lle; 2062 mtx_unlock_spin(&w_mtx); 2063 } 2064 2065 static struct lock_instance * 2066 find_instance(struct lock_list_entry *list, const struct lock_object *lock) 2067 { 2068 struct lock_list_entry *lle; 2069 struct lock_instance *instance; 2070 int i; 2071 2072 for (lle = list; lle != NULL; lle = lle->ll_next) 2073 for (i = lle->ll_count - 1; i >= 0; i--) { 2074 instance = &lle->ll_children[i]; 2075 if (instance->li_lock == lock) 2076 return (instance); 2077 } 2078 return (NULL); 2079 } 2080 2081 static void 2082 witness_list_lock(struct lock_instance *instance, 2083 int (*prnt)(const char *fmt, ...)) 2084 { 2085 struct lock_object *lock; 2086 2087 lock = instance->li_lock; 2088 prnt("%s %s %s", (instance->li_flags & LI_EXCLUSIVE) != 0 ? 2089 "exclusive" : "shared", LOCK_CLASS(lock)->lc_name, lock->lo_name); 2090 if (lock->lo_witness->w_name != lock->lo_name) 2091 prnt(" (%s)", lock->lo_witness->w_name); 2092 prnt(" r = %d (%p) locked @ %s:%d\n", 2093 instance->li_flags & LI_RECURSEMASK, lock, 2094 fixup_filename(instance->li_file), instance->li_line); 2095 } 2096 2097 #ifdef DDB 2098 static int 2099 witness_thread_has_locks(struct thread *td) 2100 { 2101 2102 if (td->td_sleeplocks == NULL) 2103 return (0); 2104 return (td->td_sleeplocks->ll_count != 0); 2105 } 2106 2107 static int 2108 witness_proc_has_locks(struct proc *p) 2109 { 2110 struct thread *td; 2111 2112 FOREACH_THREAD_IN_PROC(p, td) { 2113 if (witness_thread_has_locks(td)) 2114 return (1); 2115 } 2116 return (0); 2117 } 2118 #endif 2119 2120 int 2121 witness_list_locks(struct lock_list_entry **lock_list, 2122 int (*prnt)(const char *fmt, ...)) 2123 { 2124 struct lock_list_entry *lle; 2125 int i, nheld; 2126 2127 nheld = 0; 2128 for (lle = *lock_list; lle != NULL; lle = lle->ll_next) 2129 for (i = lle->ll_count - 1; i >= 0; i--) { 2130 witness_list_lock(&lle->ll_children[i], prnt); 2131 nheld++; 2132 } 2133 return (nheld); 2134 } 2135 2136 /* 2137 * This is a bit risky at best. We call this function when we have timed 2138 * out acquiring a spin lock, and we assume that the other CPU is stuck 2139 * with this lock held. So, we go groveling around in the other CPU's 2140 * per-cpu data to try to find the lock instance for this spin lock to 2141 * see when it was last acquired. 2142 */ 2143 void 2144 witness_display_spinlock(struct lock_object *lock, struct thread *owner, 2145 int (*prnt)(const char *fmt, ...)) 2146 { 2147 struct lock_instance *instance; 2148 struct pcpu *pc; 2149 2150 if (owner->td_critnest == 0 || owner->td_oncpu == NOCPU) 2151 return; 2152 pc = pcpu_find(owner->td_oncpu); 2153 instance = find_instance(pc->pc_spinlocks, lock); 2154 if (instance != NULL) 2155 witness_list_lock(instance, prnt); 2156 } 2157 2158 void 2159 witness_save(struct lock_object *lock, const char **filep, int *linep) 2160 { 2161 struct lock_list_entry *lock_list; 2162 struct lock_instance *instance; 2163 struct lock_class *class; 2164 2165 /* 2166 * This function is used independently in locking code to deal with 2167 * Giant, SCHEDULER_STOPPED() check can be removed here after Giant 2168 * is gone. 2169 */ 2170 if (SCHEDULER_STOPPED()) 2171 return; 2172 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); 2173 if (lock->lo_witness == NULL || witness_watch == -1 || panicstr != NULL) 2174 return; 2175 class = LOCK_CLASS(lock); 2176 if (class->lc_flags & LC_SLEEPLOCK) 2177 lock_list = curthread->td_sleeplocks; 2178 else { 2179 if (witness_skipspin) 2180 return; 2181 lock_list = PCPU_GET(spinlocks); 2182 } 2183 instance = find_instance(lock_list, lock); 2184 if (instance == NULL) 2185 panic("%s: lock (%s) %s not locked", __func__, 2186 class->lc_name, lock->lo_name); 2187 *filep = instance->li_file; 2188 *linep = instance->li_line; 2189 } 2190 2191 void 2192 witness_restore(struct lock_object *lock, const char *file, int line) 2193 { 2194 struct lock_list_entry *lock_list; 2195 struct lock_instance *instance; 2196 struct lock_class *class; 2197 2198 /* 2199 * This function is used independently in locking code to deal with 2200 * Giant, SCHEDULER_STOPPED() check can be removed here after Giant 2201 * is gone. 2202 */ 2203 if (SCHEDULER_STOPPED()) 2204 return; 2205 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); 2206 if (lock->lo_witness == NULL || witness_watch == -1 || panicstr != NULL) 2207 return; 2208 class = LOCK_CLASS(lock); 2209 if (class->lc_flags & LC_SLEEPLOCK) 2210 lock_list = curthread->td_sleeplocks; 2211 else { 2212 if (witness_skipspin) 2213 return; 2214 lock_list = PCPU_GET(spinlocks); 2215 } 2216 instance = find_instance(lock_list, lock); 2217 if (instance == NULL) 2218 panic("%s: lock (%s) %s not locked", __func__, 2219 class->lc_name, lock->lo_name); 2220 lock->lo_witness->w_file = file; 2221 lock->lo_witness->w_line = line; 2222 instance->li_file = file; 2223 instance->li_line = line; 2224 } 2225 2226 void 2227 witness_assert(const struct lock_object *lock, int flags, const char *file, 2228 int line) 2229 { 2230 #ifdef INVARIANT_SUPPORT 2231 struct lock_instance *instance; 2232 struct lock_class *class; 2233 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) != 0) 2238 instance = find_instance(curthread->td_sleeplocks, lock); 2239 else if ((class->lc_flags & LC_SPINLOCK) != 0) 2240 instance = find_instance(PCPU_GET(spinlocks), lock); 2241 else { 2242 panic("Lock (%s) %s is not sleep or spin!", 2243 class->lc_name, lock->lo_name); 2244 } 2245 switch (flags) { 2246 case LA_UNLOCKED: 2247 if (instance != NULL) 2248 panic("Lock (%s) %s locked @ %s:%d.", 2249 class->lc_name, lock->lo_name, 2250 fixup_filename(file), line); 2251 break; 2252 case LA_LOCKED: 2253 case LA_LOCKED | LA_RECURSED: 2254 case LA_LOCKED | LA_NOTRECURSED: 2255 case LA_SLOCKED: 2256 case LA_SLOCKED | LA_RECURSED: 2257 case LA_SLOCKED | LA_NOTRECURSED: 2258 case LA_XLOCKED: 2259 case LA_XLOCKED | LA_RECURSED: 2260 case LA_XLOCKED | LA_NOTRECURSED: 2261 if (instance == NULL) { 2262 panic("Lock (%s) %s not locked @ %s:%d.", 2263 class->lc_name, lock->lo_name, 2264 fixup_filename(file), line); 2265 break; 2266 } 2267 if ((flags & LA_XLOCKED) != 0 && 2268 (instance->li_flags & LI_EXCLUSIVE) == 0) 2269 panic("Lock (%s) %s not exclusively locked @ %s:%d.", 2270 class->lc_name, lock->lo_name, 2271 fixup_filename(file), line); 2272 if ((flags & LA_SLOCKED) != 0 && 2273 (instance->li_flags & LI_EXCLUSIVE) != 0) 2274 panic("Lock (%s) %s exclusively locked @ %s:%d.", 2275 class->lc_name, lock->lo_name, 2276 fixup_filename(file), line); 2277 if ((flags & LA_RECURSED) != 0 && 2278 (instance->li_flags & LI_RECURSEMASK) == 0) 2279 panic("Lock (%s) %s not recursed @ %s:%d.", 2280 class->lc_name, lock->lo_name, 2281 fixup_filename(file), line); 2282 if ((flags & LA_NOTRECURSED) != 0 && 2283 (instance->li_flags & LI_RECURSEMASK) != 0) 2284 panic("Lock (%s) %s recursed @ %s:%d.", 2285 class->lc_name, lock->lo_name, 2286 fixup_filename(file), line); 2287 break; 2288 default: 2289 panic("Invalid lock assertion at %s:%d.", 2290 fixup_filename(file), line); 2291 2292 } 2293 #endif /* INVARIANT_SUPPORT */ 2294 } 2295 2296 static void 2297 witness_setflag(struct lock_object *lock, int flag, int set) 2298 { 2299 struct lock_list_entry *lock_list; 2300 struct lock_instance *instance; 2301 struct lock_class *class; 2302 2303 if (lock->lo_witness == NULL || witness_watch == -1 || panicstr != NULL) 2304 return; 2305 class = LOCK_CLASS(lock); 2306 if (class->lc_flags & LC_SLEEPLOCK) 2307 lock_list = curthread->td_sleeplocks; 2308 else { 2309 if (witness_skipspin) 2310 return; 2311 lock_list = PCPU_GET(spinlocks); 2312 } 2313 instance = find_instance(lock_list, lock); 2314 if (instance == NULL) 2315 panic("%s: lock (%s) %s not locked", __func__, 2316 class->lc_name, lock->lo_name); 2317 2318 if (set) 2319 instance->li_flags |= flag; 2320 else 2321 instance->li_flags &= ~flag; 2322 } 2323 2324 void 2325 witness_norelease(struct lock_object *lock) 2326 { 2327 2328 witness_setflag(lock, LI_NORELEASE, 1); 2329 } 2330 2331 void 2332 witness_releaseok(struct lock_object *lock) 2333 { 2334 2335 witness_setflag(lock, LI_NORELEASE, 0); 2336 } 2337 2338 #ifdef DDB 2339 static void 2340 witness_ddb_list(struct thread *td) 2341 { 2342 2343 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); 2344 KASSERT(kdb_active, ("%s: not in the debugger", __func__)); 2345 2346 if (witness_watch < 1) 2347 return; 2348 2349 witness_list_locks(&td->td_sleeplocks, db_printf); 2350 2351 /* 2352 * We only handle spinlocks if td == curthread. This is somewhat broken 2353 * if td is currently executing on some other CPU and holds spin locks 2354 * as we won't display those locks. If we had a MI way of getting 2355 * the per-cpu data for a given cpu then we could use 2356 * td->td_oncpu to get the list of spinlocks for this thread 2357 * and "fix" this. 2358 * 2359 * That still wouldn't really fix this unless we locked the scheduler 2360 * lock or stopped the other CPU to make sure it wasn't changing the 2361 * list out from under us. It is probably best to just not try to 2362 * handle threads on other CPU's for now. 2363 */ 2364 if (td == curthread && PCPU_GET(spinlocks) != NULL) 2365 witness_list_locks(PCPU_PTR(spinlocks), db_printf); 2366 } 2367 2368 DB_SHOW_COMMAND(locks, db_witness_list) 2369 { 2370 struct thread *td; 2371 2372 if (have_addr) 2373 td = db_lookup_thread(addr, TRUE); 2374 else 2375 td = kdb_thread; 2376 witness_ddb_list(td); 2377 } 2378 2379 DB_SHOW_ALL_COMMAND(locks, db_witness_list_all) 2380 { 2381 struct thread *td; 2382 struct proc *p; 2383 2384 /* 2385 * It would be nice to list only threads and processes that actually 2386 * held sleep locks, but that information is currently not exported 2387 * by WITNESS. 2388 */ 2389 FOREACH_PROC_IN_SYSTEM(p) { 2390 if (!witness_proc_has_locks(p)) 2391 continue; 2392 FOREACH_THREAD_IN_PROC(p, td) { 2393 if (!witness_thread_has_locks(td)) 2394 continue; 2395 db_printf("Process %d (%s) thread %p (%d)\n", p->p_pid, 2396 p->p_comm, td, td->td_tid); 2397 witness_ddb_list(td); 2398 } 2399 } 2400 } 2401 DB_SHOW_ALIAS(alllocks, db_witness_list_all) 2402 2403 DB_SHOW_COMMAND(witness, db_witness_display) 2404 { 2405 2406 witness_ddb_display(db_printf); 2407 } 2408 #endif 2409 2410 static int 2411 sysctl_debug_witness_badstacks(SYSCTL_HANDLER_ARGS) 2412 { 2413 struct witness_lock_order_data *data1, *data2, *tmp_data1, *tmp_data2; 2414 struct witness *tmp_w1, *tmp_w2, *w1, *w2; 2415 struct sbuf *sb; 2416 u_int w_rmatrix1, w_rmatrix2; 2417 int error, generation, i, j; 2418 2419 tmp_data1 = NULL; 2420 tmp_data2 = NULL; 2421 tmp_w1 = NULL; 2422 tmp_w2 = NULL; 2423 if (witness_watch < 1) { 2424 error = SYSCTL_OUT(req, w_notrunning, sizeof(w_notrunning)); 2425 return (error); 2426 } 2427 if (witness_cold) { 2428 error = SYSCTL_OUT(req, w_stillcold, sizeof(w_stillcold)); 2429 return (error); 2430 } 2431 error = 0; 2432 sb = sbuf_new(NULL, NULL, BADSTACK_SBUF_SIZE, SBUF_AUTOEXTEND); 2433 if (sb == NULL) 2434 return (ENOMEM); 2435 2436 /* Allocate and init temporary storage space. */ 2437 tmp_w1 = malloc(sizeof(struct witness), M_TEMP, M_WAITOK | M_ZERO); 2438 tmp_w2 = malloc(sizeof(struct witness), M_TEMP, M_WAITOK | M_ZERO); 2439 tmp_data1 = malloc(sizeof(struct witness_lock_order_data), M_TEMP, 2440 M_WAITOK | M_ZERO); 2441 tmp_data2 = malloc(sizeof(struct witness_lock_order_data), M_TEMP, 2442 M_WAITOK | M_ZERO); 2443 stack_zero(&tmp_data1->wlod_stack); 2444 stack_zero(&tmp_data2->wlod_stack); 2445 2446 restart: 2447 mtx_lock_spin(&w_mtx); 2448 generation = w_generation; 2449 mtx_unlock_spin(&w_mtx); 2450 sbuf_printf(sb, "Number of known direct relationships is %d\n", 2451 w_lohash.wloh_count); 2452 for (i = 1; i < w_max_used_index; i++) { 2453 mtx_lock_spin(&w_mtx); 2454 if (generation != w_generation) { 2455 mtx_unlock_spin(&w_mtx); 2456 2457 /* The graph has changed, try again. */ 2458 req->oldidx = 0; 2459 sbuf_clear(sb); 2460 goto restart; 2461 } 2462 2463 w1 = &w_data[i]; 2464 if (w1->w_reversed == 0) { 2465 mtx_unlock_spin(&w_mtx); 2466 continue; 2467 } 2468 2469 /* Copy w1 locally so we can release the spin lock. */ 2470 *tmp_w1 = *w1; 2471 mtx_unlock_spin(&w_mtx); 2472 2473 if (tmp_w1->w_reversed == 0) 2474 continue; 2475 for (j = 1; j < w_max_used_index; j++) { 2476 if ((w_rmatrix[i][j] & WITNESS_REVERSAL) == 0 || i > j) 2477 continue; 2478 2479 mtx_lock_spin(&w_mtx); 2480 if (generation != w_generation) { 2481 mtx_unlock_spin(&w_mtx); 2482 2483 /* The graph has changed, try again. */ 2484 req->oldidx = 0; 2485 sbuf_clear(sb); 2486 goto restart; 2487 } 2488 2489 w2 = &w_data[j]; 2490 data1 = witness_lock_order_get(w1, w2); 2491 data2 = witness_lock_order_get(w2, w1); 2492 2493 /* 2494 * Copy information locally so we can release the 2495 * spin lock. 2496 */ 2497 *tmp_w2 = *w2; 2498 w_rmatrix1 = (unsigned int)w_rmatrix[i][j]; 2499 w_rmatrix2 = (unsigned int)w_rmatrix[j][i]; 2500 2501 if (data1) { 2502 stack_zero(&tmp_data1->wlod_stack); 2503 stack_copy(&data1->wlod_stack, 2504 &tmp_data1->wlod_stack); 2505 } 2506 if (data2 && data2 != data1) { 2507 stack_zero(&tmp_data2->wlod_stack); 2508 stack_copy(&data2->wlod_stack, 2509 &tmp_data2->wlod_stack); 2510 } 2511 mtx_unlock_spin(&w_mtx); 2512 2513 sbuf_printf(sb, 2514 "\nLock order reversal between \"%s\"(%s) and \"%s\"(%s)!\n", 2515 tmp_w1->w_name, tmp_w1->w_class->lc_name, 2516 tmp_w2->w_name, tmp_w2->w_class->lc_name); 2517 #if 0 2518 sbuf_printf(sb, 2519 "w_rmatrix[%s][%s] == %x, w_rmatrix[%s][%s] == %x\n", 2520 tmp_w1->name, tmp_w2->w_name, w_rmatrix1, 2521 tmp_w2->name, tmp_w1->w_name, w_rmatrix2); 2522 #endif 2523 if (data1) { 2524 sbuf_printf(sb, 2525 "Lock order \"%s\"(%s) -> \"%s\"(%s) first seen at:\n", 2526 tmp_w1->w_name, tmp_w1->w_class->lc_name, 2527 tmp_w2->w_name, tmp_w2->w_class->lc_name); 2528 stack_sbuf_print(sb, &tmp_data1->wlod_stack); 2529 sbuf_printf(sb, "\n"); 2530 } 2531 if (data2 && data2 != data1) { 2532 sbuf_printf(sb, 2533 "Lock order \"%s\"(%s) -> \"%s\"(%s) first seen at:\n", 2534 tmp_w2->w_name, tmp_w2->w_class->lc_name, 2535 tmp_w1->w_name, tmp_w1->w_class->lc_name); 2536 stack_sbuf_print(sb, &tmp_data2->wlod_stack); 2537 sbuf_printf(sb, "\n"); 2538 } 2539 } 2540 } 2541 mtx_lock_spin(&w_mtx); 2542 if (generation != w_generation) { 2543 mtx_unlock_spin(&w_mtx); 2544 2545 /* 2546 * The graph changed while we were printing stack data, 2547 * try again. 2548 */ 2549 req->oldidx = 0; 2550 sbuf_clear(sb); 2551 goto restart; 2552 } 2553 mtx_unlock_spin(&w_mtx); 2554 2555 /* Free temporary storage space. */ 2556 free(tmp_data1, M_TEMP); 2557 free(tmp_data2, M_TEMP); 2558 free(tmp_w1, M_TEMP); 2559 free(tmp_w2, M_TEMP); 2560 2561 sbuf_finish(sb); 2562 error = SYSCTL_OUT(req, sbuf_data(sb), sbuf_len(sb) + 1); 2563 sbuf_delete(sb); 2564 2565 return (error); 2566 } 2567 2568 static int 2569 sysctl_debug_witness_fullgraph(SYSCTL_HANDLER_ARGS) 2570 { 2571 struct witness *w; 2572 struct sbuf *sb; 2573 int error; 2574 2575 if (witness_watch < 1) { 2576 error = SYSCTL_OUT(req, w_notrunning, sizeof(w_notrunning)); 2577 return (error); 2578 } 2579 if (witness_cold) { 2580 error = SYSCTL_OUT(req, w_stillcold, sizeof(w_stillcold)); 2581 return (error); 2582 } 2583 error = 0; 2584 2585 error = sysctl_wire_old_buffer(req, 0); 2586 if (error != 0) 2587 return (error); 2588 sb = sbuf_new_for_sysctl(NULL, NULL, FULLGRAPH_SBUF_SIZE, req); 2589 if (sb == NULL) 2590 return (ENOMEM); 2591 sbuf_printf(sb, "\n"); 2592 2593 mtx_lock_spin(&w_mtx); 2594 STAILQ_FOREACH(w, &w_all, w_list) 2595 w->w_displayed = 0; 2596 STAILQ_FOREACH(w, &w_all, w_list) 2597 witness_add_fullgraph(sb, w); 2598 mtx_unlock_spin(&w_mtx); 2599 2600 /* 2601 * Close the sbuf and return to userland. 2602 */ 2603 error = sbuf_finish(sb); 2604 sbuf_delete(sb); 2605 2606 return (error); 2607 } 2608 2609 static int 2610 sysctl_debug_witness_watch(SYSCTL_HANDLER_ARGS) 2611 { 2612 int error, value; 2613 2614 value = witness_watch; 2615 error = sysctl_handle_int(oidp, &value, 0, req); 2616 if (error != 0 || req->newptr == NULL) 2617 return (error); 2618 if (value > 1 || value < -1 || 2619 (witness_watch == -1 && value != witness_watch)) 2620 return (EINVAL); 2621 witness_watch = value; 2622 return (0); 2623 } 2624 2625 static void 2626 witness_add_fullgraph(struct sbuf *sb, struct witness *w) 2627 { 2628 int i; 2629 2630 if (w->w_displayed != 0 || (w->w_file == NULL && w->w_line == 0)) 2631 return; 2632 w->w_displayed = 1; 2633 2634 WITNESS_INDEX_ASSERT(w->w_index); 2635 for (i = 1; i <= w_max_used_index; i++) { 2636 if (w_rmatrix[w->w_index][i] & WITNESS_PARENT) { 2637 sbuf_printf(sb, "\"%s\",\"%s\"\n", w->w_name, 2638 w_data[i].w_name); 2639 witness_add_fullgraph(sb, &w_data[i]); 2640 } 2641 } 2642 } 2643 2644 /* 2645 * A simple hash function. Takes a key pointer and a key size. If size == 0, 2646 * interprets the key as a string and reads until the null 2647 * terminator. Otherwise, reads the first size bytes. Returns an unsigned 32-bit 2648 * hash value computed from the key. 2649 */ 2650 static uint32_t 2651 witness_hash_djb2(const uint8_t *key, uint32_t size) 2652 { 2653 unsigned int hash = 5381; 2654 int i; 2655 2656 /* hash = hash * 33 + key[i] */ 2657 if (size) 2658 for (i = 0; i < size; i++) 2659 hash = ((hash << 5) + hash) + (unsigned int)key[i]; 2660 else 2661 for (i = 0; key[i] != 0; i++) 2662 hash = ((hash << 5) + hash) + (unsigned int)key[i]; 2663 2664 return (hash); 2665 } 2666 2667 2668 /* 2669 * Initializes the two witness hash tables. Called exactly once from 2670 * witness_initialize(). 2671 */ 2672 static void 2673 witness_init_hash_tables(void) 2674 { 2675 int i; 2676 2677 MPASS(witness_cold); 2678 2679 /* Initialize the hash tables. */ 2680 for (i = 0; i < WITNESS_HASH_SIZE; i++) 2681 w_hash.wh_array[i] = NULL; 2682 2683 w_hash.wh_size = WITNESS_HASH_SIZE; 2684 w_hash.wh_count = 0; 2685 2686 /* Initialize the lock order data hash. */ 2687 w_lofree = NULL; 2688 for (i = 0; i < WITNESS_LO_DATA_COUNT; i++) { 2689 memset(&w_lodata[i], 0, sizeof(w_lodata[i])); 2690 w_lodata[i].wlod_next = w_lofree; 2691 w_lofree = &w_lodata[i]; 2692 } 2693 w_lohash.wloh_size = WITNESS_LO_HASH_SIZE; 2694 w_lohash.wloh_count = 0; 2695 for (i = 0; i < WITNESS_LO_HASH_SIZE; i++) 2696 w_lohash.wloh_array[i] = NULL; 2697 } 2698 2699 static struct witness * 2700 witness_hash_get(const char *key) 2701 { 2702 struct witness *w; 2703 uint32_t hash; 2704 2705 MPASS(key != NULL); 2706 if (witness_cold == 0) 2707 mtx_assert(&w_mtx, MA_OWNED); 2708 hash = witness_hash_djb2(key, 0) % w_hash.wh_size; 2709 w = w_hash.wh_array[hash]; 2710 while (w != NULL) { 2711 if (strcmp(w->w_name, key) == 0) 2712 goto out; 2713 w = w->w_hash_next; 2714 } 2715 2716 out: 2717 return (w); 2718 } 2719 2720 static void 2721 witness_hash_put(struct witness *w) 2722 { 2723 uint32_t hash; 2724 2725 MPASS(w != NULL); 2726 MPASS(w->w_name != NULL); 2727 if (witness_cold == 0) 2728 mtx_assert(&w_mtx, MA_OWNED); 2729 KASSERT(witness_hash_get(w->w_name) == NULL, 2730 ("%s: trying to add a hash entry that already exists!", __func__)); 2731 KASSERT(w->w_hash_next == NULL, 2732 ("%s: w->w_hash_next != NULL", __func__)); 2733 2734 hash = witness_hash_djb2(w->w_name, 0) % w_hash.wh_size; 2735 w->w_hash_next = w_hash.wh_array[hash]; 2736 w_hash.wh_array[hash] = w; 2737 w_hash.wh_count++; 2738 } 2739 2740 2741 static struct witness_lock_order_data * 2742 witness_lock_order_get(struct witness *parent, struct witness *child) 2743 { 2744 struct witness_lock_order_data *data = NULL; 2745 struct witness_lock_order_key key; 2746 unsigned int hash; 2747 2748 MPASS(parent != NULL && child != NULL); 2749 key.from = parent->w_index; 2750 key.to = child->w_index; 2751 WITNESS_INDEX_ASSERT(key.from); 2752 WITNESS_INDEX_ASSERT(key.to); 2753 if ((w_rmatrix[parent->w_index][child->w_index] 2754 & WITNESS_LOCK_ORDER_KNOWN) == 0) 2755 goto out; 2756 2757 hash = witness_hash_djb2((const char*)&key, 2758 sizeof(key)) % w_lohash.wloh_size; 2759 data = w_lohash.wloh_array[hash]; 2760 while (data != NULL) { 2761 if (witness_lock_order_key_equal(&data->wlod_key, &key)) 2762 break; 2763 data = data->wlod_next; 2764 } 2765 2766 out: 2767 return (data); 2768 } 2769 2770 /* 2771 * Verify that parent and child have a known relationship, are not the same, 2772 * and child is actually a child of parent. This is done without w_mtx 2773 * to avoid contention in the common case. 2774 */ 2775 static int 2776 witness_lock_order_check(struct witness *parent, struct witness *child) 2777 { 2778 2779 if (parent != child && 2780 w_rmatrix[parent->w_index][child->w_index] 2781 & WITNESS_LOCK_ORDER_KNOWN && 2782 isitmychild(parent, child)) 2783 return (1); 2784 2785 return (0); 2786 } 2787 2788 static int 2789 witness_lock_order_add(struct witness *parent, struct witness *child) 2790 { 2791 struct witness_lock_order_data *data = NULL; 2792 struct witness_lock_order_key key; 2793 unsigned int hash; 2794 2795 MPASS(parent != NULL && child != NULL); 2796 key.from = parent->w_index; 2797 key.to = child->w_index; 2798 WITNESS_INDEX_ASSERT(key.from); 2799 WITNESS_INDEX_ASSERT(key.to); 2800 if (w_rmatrix[parent->w_index][child->w_index] 2801 & WITNESS_LOCK_ORDER_KNOWN) 2802 return (1); 2803 2804 hash = witness_hash_djb2((const char*)&key, 2805 sizeof(key)) % w_lohash.wloh_size; 2806 w_rmatrix[parent->w_index][child->w_index] |= WITNESS_LOCK_ORDER_KNOWN; 2807 data = w_lofree; 2808 if (data == NULL) 2809 return (0); 2810 w_lofree = data->wlod_next; 2811 data->wlod_next = w_lohash.wloh_array[hash]; 2812 data->wlod_key = key; 2813 w_lohash.wloh_array[hash] = data; 2814 w_lohash.wloh_count++; 2815 stack_zero(&data->wlod_stack); 2816 stack_save(&data->wlod_stack); 2817 return (1); 2818 } 2819 2820 /* Call this whenver the structure of the witness graph changes. */ 2821 static void 2822 witness_increment_graph_generation(void) 2823 { 2824 2825 if (witness_cold == 0) 2826 mtx_assert(&w_mtx, MA_OWNED); 2827 w_generation++; 2828 } 2829 2830 #ifdef KDB 2831 static void 2832 _witness_debugger(int cond, const char *msg) 2833 { 2834 2835 if (witness_trace && cond) 2836 kdb_backtrace(); 2837 if (witness_kdb && cond) 2838 kdb_enter(KDB_WHY_WITNESS, msg); 2839 } 2840 #endif 2841