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 512 139 140 /* 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 CYCLEGRAPH_SBUF_SIZE 8192 158 #define FULLGRAPH_SBUF_SIZE 32768 159 160 /* 161 * These flags go in the witness relationship matrix and describe the 162 * relationship between any two struct witness objects. 163 */ 164 #define WITNESS_UNRELATED 0x00 /* No lock order relation. */ 165 #define WITNESS_PARENT 0x01 /* Parent, aka direct ancestor. */ 166 #define WITNESS_ANCESTOR 0x02 /* Direct or indirect ancestor. */ 167 #define WITNESS_CHILD 0x04 /* Child, aka direct descendant. */ 168 #define WITNESS_DESCENDANT 0x08 /* Direct or indirect descendant. */ 169 #define WITNESS_ANCESTOR_MASK (WITNESS_PARENT | WITNESS_ANCESTOR) 170 #define WITNESS_DESCENDANT_MASK (WITNESS_CHILD | WITNESS_DESCENDANT) 171 #define WITNESS_RELATED_MASK \ 172 (WITNESS_ANCESTOR_MASK | WITNESS_DESCENDANT_MASK) 173 #define WITNESS_REVERSAL 0x10 /* A lock order reversal has been 174 * observed. */ 175 #define WITNESS_RESERVED1 0x20 /* Unused flag, reserved. */ 176 #define WITNESS_RESERVED2 0x40 /* Unused flag, reserved. */ 177 #define WITNESS_LOCK_ORDER_KNOWN 0x80 /* This lock order is known. */ 178 179 /* Descendant to ancestor flags */ 180 #define WITNESS_DTOA(x) (((x) & WITNESS_RELATED_MASK) >> 2) 181 182 /* Ancestor to descendant flags */ 183 #define WITNESS_ATOD(x) (((x) & WITNESS_RELATED_MASK) << 2) 184 185 #define WITNESS_INDEX_ASSERT(i) \ 186 MPASS((i) > 0 && (i) <= w_max_used_index && (i) < WITNESS_COUNT) 187 188 MALLOC_DEFINE(M_WITNESS, "Witness", "Witness"); 189 190 /* 191 * Lock instances. A lock instance is the data associated with a lock while 192 * it is held by witness. For example, a lock instance will hold the 193 * recursion count of a lock. Lock instances are held in lists. Spin locks 194 * are held in a per-cpu list while sleep locks are held in per-thread list. 195 */ 196 struct lock_instance { 197 struct lock_object *li_lock; 198 const char *li_file; 199 int li_line; 200 u_int li_flags; 201 }; 202 203 /* 204 * A simple list type used to build the list of locks held by a thread 205 * or CPU. We can't simply embed the list in struct lock_object since a 206 * lock may be held by more than one thread if it is a shared lock. Locks 207 * are added to the head of the list, so we fill up each list entry from 208 * "the back" logically. To ease some of the arithmetic, we actually fill 209 * in each list entry the normal way (children[0] then children[1], etc.) but 210 * when we traverse the list we read children[count-1] as the first entry 211 * down to children[0] as the final entry. 212 */ 213 struct lock_list_entry { 214 struct lock_list_entry *ll_next; 215 struct lock_instance ll_children[LOCK_NCHILDREN]; 216 u_int ll_count; 217 }; 218 219 /* 220 * The main witness structure. One of these per named lock type in the system 221 * (for example, "vnode interlock"). 222 */ 223 struct witness { 224 char w_name[MAX_W_NAME]; 225 uint32_t w_index; /* Index in the relationship matrix */ 226 struct lock_class *w_class; 227 STAILQ_ENTRY(witness) w_list; /* List of all witnesses. */ 228 STAILQ_ENTRY(witness) w_typelist; /* Witnesses of a type. */ 229 struct witness *w_hash_next; /* Linked list in hash buckets. */ 230 const char *w_file; /* File where last acquired */ 231 uint32_t w_line; /* Line where last acquired */ 232 uint32_t w_refcount; 233 uint16_t w_num_ancestors; /* direct/indirect 234 * ancestor count */ 235 uint16_t w_num_descendants; /* direct/indirect 236 * descendant count */ 237 int16_t w_ddb_level; 238 unsigned w_displayed:1; 239 unsigned w_reversed:1; 240 }; 241 242 STAILQ_HEAD(witness_list, witness); 243 244 /* 245 * The witness hash table. Keys are witness names (const char *), elements are 246 * witness objects (struct witness *). 247 */ 248 struct witness_hash { 249 struct witness *wh_array[WITNESS_HASH_SIZE]; 250 uint32_t wh_size; 251 uint32_t wh_count; 252 }; 253 254 /* 255 * Key type for the lock order data hash table. 256 */ 257 struct witness_lock_order_key { 258 uint16_t from; 259 uint16_t to; 260 }; 261 262 struct witness_lock_order_data { 263 struct stack wlod_stack; 264 struct witness_lock_order_key wlod_key; 265 struct witness_lock_order_data *wlod_next; 266 }; 267 268 /* 269 * The witness lock order data hash table. Keys are witness index tuples 270 * (struct witness_lock_order_key), elements are lock order data objects 271 * (struct witness_lock_order_data). 272 */ 273 struct witness_lock_order_hash { 274 struct witness_lock_order_data *wloh_array[WITNESS_LO_HASH_SIZE]; 275 u_int wloh_size; 276 u_int wloh_count; 277 }; 278 279 #ifdef BLESSING 280 struct witness_blessed { 281 const char *b_lock1; 282 const char *b_lock2; 283 }; 284 #endif 285 286 struct witness_pendhelp { 287 const char *wh_type; 288 struct lock_object *wh_lock; 289 }; 290 291 struct witness_order_list_entry { 292 const char *w_name; 293 struct lock_class *w_class; 294 }; 295 296 /* 297 * Returns 0 if one of the locks is a spin lock and the other is not. 298 * Returns 1 otherwise. 299 */ 300 static __inline int 301 witness_lock_type_equal(struct witness *w1, struct witness *w2) 302 { 303 304 return ((w1->w_class->lc_flags & (LC_SLEEPLOCK | LC_SPINLOCK)) == 305 (w2->w_class->lc_flags & (LC_SLEEPLOCK | LC_SPINLOCK))); 306 } 307 308 static __inline int 309 witness_lock_order_key_empty(const struct witness_lock_order_key *key) 310 { 311 312 return (key->from == 0 && key->to == 0); 313 } 314 315 static __inline int 316 witness_lock_order_key_equal(const struct witness_lock_order_key *a, 317 const struct witness_lock_order_key *b) 318 { 319 320 return (a->from == b->from && a->to == b->to); 321 } 322 323 static int _isitmyx(struct witness *w1, struct witness *w2, int rmask, 324 const char *fname); 325 #ifdef KDB 326 static void _witness_debugger(int cond, const char *msg); 327 #endif 328 static void adopt(struct witness *parent, struct witness *child); 329 #ifdef BLESSING 330 static int blessed(struct witness *, struct witness *); 331 #endif 332 static void depart(struct witness *w); 333 static struct witness *enroll(const char *description, 334 struct lock_class *lock_class); 335 static struct lock_instance *find_instance(struct lock_list_entry *list, 336 struct lock_object *lock); 337 static int isitmychild(struct witness *parent, struct witness *child); 338 static int isitmydescendant(struct witness *parent, struct witness *child); 339 static void itismychild(struct witness *parent, struct witness *child); 340 static int sysctl_debug_witness_badstacks(SYSCTL_HANDLER_ARGS); 341 static int sysctl_debug_witness_watch(SYSCTL_HANDLER_ARGS); 342 static int sysctl_debug_witness_fullgraph(SYSCTL_HANDLER_ARGS); 343 static void witness_add_fullgraph(struct sbuf *sb, struct witness *parent); 344 #ifdef DDB 345 static void witness_ddb_compute_levels(void); 346 static void witness_ddb_display(int(*)(const char *fmt, ...)); 347 static void witness_ddb_display_descendants(int(*)(const char *fmt, ...), 348 struct witness *, int indent); 349 static void witness_ddb_display_list(int(*prnt)(const char *fmt, ...), 350 struct witness_list *list); 351 static void witness_ddb_level_descendants(struct witness *parent, int l); 352 static void witness_ddb_list(struct thread *td); 353 #endif 354 static void witness_free(struct witness *m); 355 static struct witness *witness_get(void); 356 static uint32_t witness_hash_djb2(const uint8_t *key, uint32_t size); 357 static struct witness *witness_hash_get(const char *key); 358 static void witness_hash_put(struct witness *w); 359 static void witness_init_hash_tables(void); 360 static void witness_increment_graph_generation(void); 361 static void witness_lock_list_free(struct lock_list_entry *lle); 362 static struct lock_list_entry *witness_lock_list_get(void); 363 static int witness_lock_order_add(struct witness *parent, 364 struct witness *child); 365 static int witness_lock_order_check(struct witness *parent, 366 struct witness *child); 367 static struct witness_lock_order_data *witness_lock_order_get( 368 struct witness *parent, 369 struct witness *child); 370 static void witness_list_lock(struct lock_instance *instance, 371 int (*prnt)(const char *fmt, ...)); 372 static void witness_setflag(struct lock_object *lock, int flag, int set); 373 374 #ifdef KDB 375 #define witness_debugger(c) _witness_debugger(c, __func__) 376 #else 377 #define witness_debugger(c) 378 #endif 379 380 SYSCTL_NODE(_debug, OID_AUTO, witness, CTLFLAG_RW, NULL, "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 { NULL, NULL }, 499 /* 500 * Sockets 501 */ 502 { "accept", &lock_class_mtx_sleep }, 503 { "so_snd", &lock_class_mtx_sleep }, 504 { "so_rcv", &lock_class_mtx_sleep }, 505 { "sellck", &lock_class_mtx_sleep }, 506 { NULL, NULL }, 507 /* 508 * Routing 509 */ 510 { "so_rcv", &lock_class_mtx_sleep }, 511 { "radix node head", &lock_class_rw }, 512 { "rtentry", &lock_class_mtx_sleep }, 513 { "ifaddr", &lock_class_mtx_sleep }, 514 { NULL, NULL }, 515 /* 516 * IPv4 multicast: 517 * protocol locks before interface locks, after UDP locks. 518 */ 519 { "udpinp", &lock_class_rw }, 520 { "in_multi_mtx", &lock_class_mtx_sleep }, 521 { "igmp_mtx", &lock_class_mtx_sleep }, 522 { "if_addr_mtx", &lock_class_mtx_sleep }, 523 { NULL, NULL }, 524 /* 525 * IPv6 multicast: 526 * protocol locks before interface locks, after UDP locks. 527 */ 528 { "udpinp", &lock_class_rw }, 529 { "in6_multi_mtx", &lock_class_mtx_sleep }, 530 { "mld_mtx", &lock_class_mtx_sleep }, 531 { "if_addr_mtx", &lock_class_mtx_sleep }, 532 { NULL, NULL }, 533 /* 534 * UNIX Domain Sockets 535 */ 536 { "unp_global_rwlock", &lock_class_rw }, 537 { "unp_list_lock", &lock_class_mtx_sleep }, 538 { "unp", &lock_class_mtx_sleep }, 539 { "so_snd", &lock_class_mtx_sleep }, 540 { NULL, NULL }, 541 /* 542 * UDP/IP 543 */ 544 { "udp", &lock_class_rw }, 545 { "udpinp", &lock_class_rw }, 546 { "so_snd", &lock_class_mtx_sleep }, 547 { NULL, NULL }, 548 /* 549 * TCP/IP 550 */ 551 { "tcp", &lock_class_rw }, 552 { "tcpinp", &lock_class_rw }, 553 { "so_snd", &lock_class_mtx_sleep }, 554 { NULL, NULL }, 555 /* 556 * netatalk 557 */ 558 { "ddp_list_mtx", &lock_class_mtx_sleep }, 559 { "ddp_mtx", &lock_class_mtx_sleep }, 560 { NULL, NULL }, 561 /* 562 * BPF 563 */ 564 { "bpf global lock", &lock_class_mtx_sleep }, 565 { "bpf interface lock", &lock_class_mtx_sleep }, 566 { "bpf cdev lock", &lock_class_mtx_sleep }, 567 { NULL, NULL }, 568 /* 569 * NFS server 570 */ 571 { "nfsd_mtx", &lock_class_mtx_sleep }, 572 { "so_snd", &lock_class_mtx_sleep }, 573 { NULL, NULL }, 574 575 /* 576 * IEEE 802.11 577 */ 578 { "802.11 com lock", &lock_class_mtx_sleep}, 579 { NULL, NULL }, 580 /* 581 * Network drivers 582 */ 583 { "network driver", &lock_class_mtx_sleep}, 584 { NULL, NULL }, 585 586 /* 587 * Netgraph 588 */ 589 { "ng_node", &lock_class_mtx_sleep }, 590 { "ng_worklist", &lock_class_mtx_sleep }, 591 { NULL, NULL }, 592 /* 593 * CDEV 594 */ 595 { "system map", &lock_class_mtx_sleep }, 596 { "vm page queue mutex", &lock_class_mtx_sleep }, 597 { "vnode interlock", &lock_class_mtx_sleep }, 598 { "cdev", &lock_class_mtx_sleep }, 599 { NULL, NULL }, 600 /* 601 * VM 602 * 603 */ 604 { "vm object", &lock_class_mtx_sleep }, 605 { "page lock", &lock_class_mtx_sleep }, 606 { "vm page queue mutex", &lock_class_mtx_sleep }, 607 { "pmap", &lock_class_mtx_sleep }, 608 { NULL, NULL }, 609 /* 610 * kqueue/VFS interaction 611 */ 612 { "kqueue", &lock_class_mtx_sleep }, 613 { "struct mount mtx", &lock_class_mtx_sleep }, 614 { "vnode interlock", &lock_class_mtx_sleep }, 615 { NULL, NULL }, 616 /* 617 * ZFS locking 618 */ 619 { "dn->dn_mtx", &lock_class_sx }, 620 { "dr->dt.di.dr_mtx", &lock_class_sx }, 621 { "db->db_mtx", &lock_class_sx }, 622 { NULL, NULL }, 623 /* 624 * spin locks 625 */ 626 #ifdef SMP 627 { "ap boot", &lock_class_mtx_spin }, 628 #endif 629 { "rm.mutex_mtx", &lock_class_mtx_spin }, 630 { "sio", &lock_class_mtx_spin }, 631 { "scrlock", &lock_class_mtx_spin }, 632 #ifdef __i386__ 633 { "cy", &lock_class_mtx_spin }, 634 #endif 635 #ifdef __sparc64__ 636 { "pcib_mtx", &lock_class_mtx_spin }, 637 { "rtc_mtx", &lock_class_mtx_spin }, 638 #endif 639 { "scc_hwmtx", &lock_class_mtx_spin }, 640 { "uart_hwmtx", &lock_class_mtx_spin }, 641 { "fast_taskqueue", &lock_class_mtx_spin }, 642 { "intr table", &lock_class_mtx_spin }, 643 #ifdef HWPMC_HOOKS 644 { "pmc-per-proc", &lock_class_mtx_spin }, 645 #endif 646 { "process slock", &lock_class_mtx_spin }, 647 { "sleepq chain", &lock_class_mtx_spin }, 648 { "umtx lock", &lock_class_mtx_spin }, 649 { "rm_spinlock", &lock_class_mtx_spin }, 650 { "turnstile chain", &lock_class_mtx_spin }, 651 { "turnstile lock", &lock_class_mtx_spin }, 652 { "sched lock", &lock_class_mtx_spin }, 653 { "td_contested", &lock_class_mtx_spin }, 654 { "callout", &lock_class_mtx_spin }, 655 { "entropy harvest mutex", &lock_class_mtx_spin }, 656 { "syscons video lock", &lock_class_mtx_spin }, 657 { "time 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 /* 724 * The WITNESS-enabled diagnostic code. Note that the witness code does 725 * assume that the early boot is single-threaded at least until after this 726 * routine is completed. 727 */ 728 static void 729 witness_initialize(void *dummy __unused) 730 { 731 struct lock_object *lock; 732 struct witness_order_list_entry *order; 733 struct witness *w, *w1; 734 int i; 735 736 w_data = malloc(sizeof (struct witness) * WITNESS_COUNT, M_WITNESS, 737 M_NOWAIT | M_ZERO); 738 739 /* 740 * We have to release Giant before initializing its witness 741 * structure so that WITNESS doesn't get confused. 742 */ 743 mtx_unlock(&Giant); 744 mtx_assert(&Giant, MA_NOTOWNED); 745 746 CTR1(KTR_WITNESS, "%s: initializing witness", __func__); 747 mtx_init(&w_mtx, "witness lock", NULL, MTX_SPIN | MTX_QUIET | 748 MTX_NOWITNESS | MTX_NOPROFILE); 749 for (i = WITNESS_COUNT - 1; i >= 0; i--) { 750 w = &w_data[i]; 751 memset(w, 0, sizeof(*w)); 752 w_data[i].w_index = i; /* Witness index never changes. */ 753 witness_free(w); 754 } 755 KASSERT(STAILQ_FIRST(&w_free)->w_index == 0, 756 ("%s: Invalid list of free witness objects", __func__)); 757 758 /* Witness with index 0 is not used to aid in debugging. */ 759 STAILQ_REMOVE_HEAD(&w_free, w_list); 760 w_free_cnt--; 761 762 memset(w_rmatrix, 0, 763 (sizeof(**w_rmatrix) * (WITNESS_COUNT+1) * (WITNESS_COUNT+1))); 764 765 for (i = 0; i < LOCK_CHILDCOUNT; i++) 766 witness_lock_list_free(&w_locklistdata[i]); 767 witness_init_hash_tables(); 768 769 /* First add in all the specified order lists. */ 770 for (order = order_lists; order->w_name != NULL; order++) { 771 w = enroll(order->w_name, order->w_class); 772 if (w == NULL) 773 continue; 774 w->w_file = "order list"; 775 for (order++; order->w_name != NULL; order++) { 776 w1 = enroll(order->w_name, order->w_class); 777 if (w1 == NULL) 778 continue; 779 w1->w_file = "order list"; 780 itismychild(w, w1); 781 w = w1; 782 } 783 } 784 witness_spin_warn = 1; 785 786 /* Iterate through all locks and add them to witness. */ 787 for (i = 0; pending_locks[i].wh_lock != NULL; i++) { 788 lock = pending_locks[i].wh_lock; 789 KASSERT(lock->lo_flags & LO_WITNESS, 790 ("%s: lock %s is on pending list but not LO_WITNESS", 791 __func__, lock->lo_name)); 792 lock->lo_witness = enroll(pending_locks[i].wh_type, 793 LOCK_CLASS(lock)); 794 } 795 796 /* Mark the witness code as being ready for use. */ 797 witness_cold = 0; 798 799 mtx_lock(&Giant); 800 } 801 SYSINIT(witness_init, SI_SUB_WITNESS, SI_ORDER_FIRST, witness_initialize, 802 NULL); 803 804 void 805 witness_init(struct lock_object *lock, const char *type) 806 { 807 struct lock_class *class; 808 809 /* Various sanity checks. */ 810 class = LOCK_CLASS(lock); 811 if ((lock->lo_flags & LO_RECURSABLE) != 0 && 812 (class->lc_flags & LC_RECURSABLE) == 0) 813 panic("%s: lock (%s) %s can not be recursable", __func__, 814 class->lc_name, lock->lo_name); 815 if ((lock->lo_flags & LO_SLEEPABLE) != 0 && 816 (class->lc_flags & LC_SLEEPABLE) == 0) 817 panic("%s: lock (%s) %s can not be sleepable", __func__, 818 class->lc_name, lock->lo_name); 819 if ((lock->lo_flags & LO_UPGRADABLE) != 0 && 820 (class->lc_flags & LC_UPGRADABLE) == 0) 821 panic("%s: lock (%s) %s can not be upgradable", __func__, 822 class->lc_name, lock->lo_name); 823 824 /* 825 * If we shouldn't watch this lock, then just clear lo_witness. 826 * Otherwise, if witness_cold is set, then it is too early to 827 * enroll this lock, so defer it to witness_initialize() by adding 828 * it to the pending_locks list. If it is not too early, then enroll 829 * the lock now. 830 */ 831 if (witness_watch < 1 || panicstr != NULL || 832 (lock->lo_flags & LO_WITNESS) == 0) 833 lock->lo_witness = NULL; 834 else if (witness_cold) { 835 pending_locks[pending_cnt].wh_lock = lock; 836 pending_locks[pending_cnt++].wh_type = type; 837 if (pending_cnt > WITNESS_PENDLIST) 838 panic("%s: pending locks list is too small, bump it\n", 839 __func__); 840 } else 841 lock->lo_witness = enroll(type, class); 842 } 843 844 void 845 witness_destroy(struct lock_object *lock) 846 { 847 struct lock_class *class; 848 struct witness *w; 849 850 class = LOCK_CLASS(lock); 851 852 if (witness_cold) 853 panic("lock (%s) %s destroyed while witness_cold", 854 class->lc_name, lock->lo_name); 855 856 /* XXX: need to verify that no one holds the lock */ 857 if ((lock->lo_flags & LO_WITNESS) == 0 || lock->lo_witness == NULL) 858 return; 859 w = lock->lo_witness; 860 861 mtx_lock_spin(&w_mtx); 862 MPASS(w->w_refcount > 0); 863 w->w_refcount--; 864 865 if (w->w_refcount == 0) 866 depart(w); 867 mtx_unlock_spin(&w_mtx); 868 } 869 870 #ifdef DDB 871 static void 872 witness_ddb_compute_levels(void) 873 { 874 struct witness *w; 875 876 /* 877 * First clear all levels. 878 */ 879 STAILQ_FOREACH(w, &w_all, w_list) 880 w->w_ddb_level = -1; 881 882 /* 883 * Look for locks with no parents and level all their descendants. 884 */ 885 STAILQ_FOREACH(w, &w_all, w_list) { 886 887 /* If the witness has ancestors (is not a root), skip it. */ 888 if (w->w_num_ancestors > 0) 889 continue; 890 witness_ddb_level_descendants(w, 0); 891 } 892 } 893 894 static void 895 witness_ddb_level_descendants(struct witness *w, int l) 896 { 897 int i; 898 899 if (w->w_ddb_level >= l) 900 return; 901 902 w->w_ddb_level = l; 903 l++; 904 905 for (i = 1; i <= w_max_used_index; i++) { 906 if (w_rmatrix[w->w_index][i] & WITNESS_PARENT) 907 witness_ddb_level_descendants(&w_data[i], l); 908 } 909 } 910 911 static void 912 witness_ddb_display_descendants(int(*prnt)(const char *fmt, ...), 913 struct witness *w, int indent) 914 { 915 int i; 916 917 for (i = 0; i < indent; i++) 918 prnt(" "); 919 prnt("%s (type: %s, depth: %d, active refs: %d)", 920 w->w_name, w->w_class->lc_name, 921 w->w_ddb_level, w->w_refcount); 922 if (w->w_displayed) { 923 prnt(" -- (already displayed)\n"); 924 return; 925 } 926 w->w_displayed = 1; 927 if (w->w_file != NULL && w->w_line != 0) 928 prnt(" -- last acquired @ %s:%d\n", w->w_file, 929 w->w_line); 930 else 931 prnt(" -- never acquired\n"); 932 indent++; 933 WITNESS_INDEX_ASSERT(w->w_index); 934 for (i = 1; i <= w_max_used_index; i++) { 935 if (w_rmatrix[w->w_index][i] & WITNESS_PARENT) 936 witness_ddb_display_descendants(prnt, &w_data[i], 937 indent); 938 } 939 } 940 941 static void 942 witness_ddb_display_list(int(*prnt)(const char *fmt, ...), 943 struct witness_list *list) 944 { 945 struct witness *w; 946 947 STAILQ_FOREACH(w, list, w_typelist) { 948 if (w->w_file == NULL || w->w_ddb_level > 0) 949 continue; 950 951 /* This lock has no anscestors - display its descendants. */ 952 witness_ddb_display_descendants(prnt, w, 0); 953 } 954 } 955 956 static void 957 witness_ddb_display(int(*prnt)(const char *fmt, ...)) 958 { 959 struct witness *w; 960 961 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); 962 witness_ddb_compute_levels(); 963 964 /* Clear all the displayed flags. */ 965 STAILQ_FOREACH(w, &w_all, w_list) 966 w->w_displayed = 0; 967 968 /* 969 * First, handle sleep locks which have been acquired at least 970 * once. 971 */ 972 prnt("Sleep locks:\n"); 973 witness_ddb_display_list(prnt, &w_sleep); 974 975 /* 976 * Now do spin locks which have been acquired at least once. 977 */ 978 prnt("\nSpin locks:\n"); 979 witness_ddb_display_list(prnt, &w_spin); 980 981 /* 982 * Finally, any locks which have not been acquired yet. 983 */ 984 prnt("\nLocks which were never acquired:\n"); 985 STAILQ_FOREACH(w, &w_all, w_list) { 986 if (w->w_file != NULL || w->w_refcount == 0) 987 continue; 988 prnt("%s (type: %s, depth: %d)\n", w->w_name, 989 w->w_class->lc_name, w->w_ddb_level); 990 } 991 } 992 #endif /* DDB */ 993 994 /* Trim useless garbage from filenames. */ 995 static const char * 996 fixup_filename(const char *file) 997 { 998 999 if (file == NULL) 1000 return (NULL); 1001 while (strncmp(file, "../", 3) == 0) 1002 file += 3; 1003 return (file); 1004 } 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 file = fixup_filename(file); 1058 1059 if (class->lc_flags & LC_SLEEPLOCK) { 1060 1061 /* 1062 * Since spin locks include a critical section, this check 1063 * implicitly enforces a lock order of all sleep locks before 1064 * all spin locks. 1065 */ 1066 if (td->td_critnest != 0 && !kdb_active) 1067 panic("blockable sleep lock (%s) %s @ %s:%d", 1068 class->lc_name, lock->lo_name, 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, file, line); 1107 printf("while exclusively locked from %s:%d\n", 1108 lock1->li_file, lock1->li_line); 1109 panic("share->excl"); 1110 } 1111 if ((lock1->li_flags & LI_EXCLUSIVE) == 0 && 1112 (flags & LOP_EXCLUSIVE) != 0) { 1113 printf("exclusive lock of (%s) %s @ %s:%d\n", 1114 class->lc_name, lock->lo_name, file, line); 1115 printf("while share locked from %s:%d\n", 1116 lock1->li_file, lock1->li_line); 1117 panic("excl->share"); 1118 } 1119 return; 1120 } 1121 1122 /* 1123 * Find the previously acquired lock, but ignore interlocks. 1124 */ 1125 plock = &lock_list->ll_children[lock_list->ll_count - 1]; 1126 if (interlock != NULL && plock->li_lock == interlock) { 1127 if (lock_list->ll_count > 1) 1128 plock = 1129 &lock_list->ll_children[lock_list->ll_count - 2]; 1130 else { 1131 lle = lock_list->ll_next; 1132 1133 /* 1134 * The interlock is the only lock we hold, so 1135 * simply return. 1136 */ 1137 if (lle == NULL) 1138 return; 1139 plock = &lle->ll_children[lle->ll_count - 1]; 1140 } 1141 } 1142 1143 /* 1144 * Try to perform most checks without a lock. If this succeeds we 1145 * can skip acquiring the lock and return success. 1146 */ 1147 w1 = plock->li_lock->lo_witness; 1148 if (witness_lock_order_check(w1, w)) 1149 return; 1150 1151 /* 1152 * Check for duplicate locks of the same type. Note that we only 1153 * have to check for this on the last lock we just acquired. Any 1154 * other cases will be caught as lock order violations. 1155 */ 1156 mtx_lock_spin(&w_mtx); 1157 witness_lock_order_add(w1, w); 1158 if (w1 == w) { 1159 i = w->w_index; 1160 if (!(lock->lo_flags & LO_DUPOK) && !(flags & LOP_DUPOK) && 1161 !(w_rmatrix[i][i] & WITNESS_REVERSAL)) { 1162 w_rmatrix[i][i] |= WITNESS_REVERSAL; 1163 w->w_reversed = 1; 1164 mtx_unlock_spin(&w_mtx); 1165 printf( 1166 "acquiring duplicate lock of same type: \"%s\"\n", 1167 w->w_name); 1168 printf(" 1st %s @ %s:%d\n", plock->li_lock->lo_name, 1169 plock->li_file, plock->li_line); 1170 printf(" 2nd %s @ %s:%d\n", lock->lo_name, file, line); 1171 witness_debugger(1); 1172 } else 1173 mtx_unlock_spin(&w_mtx); 1174 return; 1175 } 1176 mtx_assert(&w_mtx, MA_OWNED); 1177 1178 /* 1179 * If we know that the the lock we are acquiring comes after 1180 * the lock we most recently acquired in the lock order tree, 1181 * then there is no need for any further checks. 1182 */ 1183 if (isitmychild(w1, w)) 1184 goto out; 1185 1186 for (j = 0, lle = lock_list; lle != NULL; lle = lle->ll_next) { 1187 for (i = lle->ll_count - 1; i >= 0; i--, j++) { 1188 1189 MPASS(j < WITNESS_COUNT); 1190 lock1 = &lle->ll_children[i]; 1191 1192 /* 1193 * Ignore the interlock the first time we see it. 1194 */ 1195 if (interlock != NULL && interlock == lock1->li_lock) { 1196 interlock = NULL; 1197 continue; 1198 } 1199 1200 /* 1201 * If this lock doesn't undergo witness checking, 1202 * then skip it. 1203 */ 1204 w1 = lock1->li_lock->lo_witness; 1205 if (w1 == NULL) { 1206 KASSERT((lock1->li_lock->lo_flags & LO_WITNESS) == 0, 1207 ("lock missing witness structure")); 1208 continue; 1209 } 1210 1211 /* 1212 * If we are locking Giant and this is a sleepable 1213 * lock, then skip it. 1214 */ 1215 if ((lock1->li_lock->lo_flags & LO_SLEEPABLE) != 0 && 1216 lock == &Giant.lock_object) 1217 continue; 1218 1219 /* 1220 * If we are locking a sleepable lock and this lock 1221 * is Giant, then skip it. 1222 */ 1223 if ((lock->lo_flags & LO_SLEEPABLE) != 0 && 1224 lock1->li_lock == &Giant.lock_object) 1225 continue; 1226 1227 /* 1228 * If we are locking a sleepable lock and this lock 1229 * isn't sleepable, we want to treat it as a lock 1230 * order violation to enfore a general lock order of 1231 * sleepable locks before non-sleepable locks. 1232 */ 1233 if (((lock->lo_flags & LO_SLEEPABLE) != 0 && 1234 (lock1->li_lock->lo_flags & LO_SLEEPABLE) == 0)) 1235 goto reversal; 1236 1237 /* 1238 * If we are locking Giant and this is a non-sleepable 1239 * lock, then treat it as a reversal. 1240 */ 1241 if ((lock1->li_lock->lo_flags & LO_SLEEPABLE) == 0 && 1242 lock == &Giant.lock_object) 1243 goto reversal; 1244 1245 /* 1246 * Check the lock order hierarchy for a reveresal. 1247 */ 1248 if (!isitmydescendant(w, w1)) 1249 continue; 1250 reversal: 1251 1252 /* 1253 * We have a lock order violation, check to see if it 1254 * is allowed or has already been yelled about. 1255 */ 1256 #ifdef BLESSING 1257 1258 /* 1259 * If the lock order is blessed, just bail. We don't 1260 * look for other lock order violations though, which 1261 * may be a bug. 1262 */ 1263 if (blessed(w, w1)) 1264 goto out; 1265 #endif 1266 1267 /* Bail if this violation is known */ 1268 if (w_rmatrix[w1->w_index][w->w_index] & WITNESS_REVERSAL) 1269 goto out; 1270 1271 /* Record this as a violation */ 1272 w_rmatrix[w1->w_index][w->w_index] |= WITNESS_REVERSAL; 1273 w_rmatrix[w->w_index][w1->w_index] |= WITNESS_REVERSAL; 1274 w->w_reversed = w1->w_reversed = 1; 1275 witness_increment_graph_generation(); 1276 mtx_unlock_spin(&w_mtx); 1277 1278 /* 1279 * Ok, yell about it. 1280 */ 1281 if (((lock->lo_flags & LO_SLEEPABLE) != 0 && 1282 (lock1->li_lock->lo_flags & LO_SLEEPABLE) == 0)) 1283 printf( 1284 "lock order reversal: (sleepable after non-sleepable)\n"); 1285 else if ((lock1->li_lock->lo_flags & LO_SLEEPABLE) == 0 1286 && lock == &Giant.lock_object) 1287 printf( 1288 "lock order reversal: (Giant after non-sleepable)\n"); 1289 else 1290 printf("lock order reversal:\n"); 1291 1292 /* 1293 * Try to locate an earlier lock with 1294 * witness w in our list. 1295 */ 1296 do { 1297 lock2 = &lle->ll_children[i]; 1298 MPASS(lock2->li_lock != NULL); 1299 if (lock2->li_lock->lo_witness == w) 1300 break; 1301 if (i == 0 && lle->ll_next != NULL) { 1302 lle = lle->ll_next; 1303 i = lle->ll_count - 1; 1304 MPASS(i >= 0 && i < LOCK_NCHILDREN); 1305 } else 1306 i--; 1307 } while (i >= 0); 1308 if (i < 0) { 1309 printf(" 1st %p %s (%s) @ %s:%d\n", 1310 lock1->li_lock, lock1->li_lock->lo_name, 1311 w1->w_name, lock1->li_file, lock1->li_line); 1312 printf(" 2nd %p %s (%s) @ %s:%d\n", lock, 1313 lock->lo_name, w->w_name, file, line); 1314 } else { 1315 printf(" 1st %p %s (%s) @ %s:%d\n", 1316 lock2->li_lock, lock2->li_lock->lo_name, 1317 lock2->li_lock->lo_witness->w_name, 1318 lock2->li_file, lock2->li_line); 1319 printf(" 2nd %p %s (%s) @ %s:%d\n", 1320 lock1->li_lock, lock1->li_lock->lo_name, 1321 w1->w_name, lock1->li_file, lock1->li_line); 1322 printf(" 3rd %p %s (%s) @ %s:%d\n", lock, 1323 lock->lo_name, w->w_name, file, line); 1324 } 1325 witness_debugger(1); 1326 return; 1327 } 1328 } 1329 1330 /* 1331 * If requested, build a new lock order. However, don't build a new 1332 * relationship between a sleepable lock and Giant if it is in the 1333 * wrong direction. The correct lock order is that sleepable locks 1334 * always come before Giant. 1335 */ 1336 if (flags & LOP_NEWORDER && 1337 !(plock->li_lock == &Giant.lock_object && 1338 (lock->lo_flags & LO_SLEEPABLE) != 0)) { 1339 CTR3(KTR_WITNESS, "%s: adding %s as a child of %s", __func__, 1340 w->w_name, plock->li_lock->lo_witness->w_name); 1341 itismychild(plock->li_lock->lo_witness, w); 1342 } 1343 out: 1344 mtx_unlock_spin(&w_mtx); 1345 } 1346 1347 void 1348 witness_lock(struct lock_object *lock, int flags, const char *file, int line) 1349 { 1350 struct lock_list_entry **lock_list, *lle; 1351 struct lock_instance *instance; 1352 struct witness *w; 1353 struct thread *td; 1354 1355 if (witness_cold || witness_watch == -1 || lock->lo_witness == NULL || 1356 panicstr != NULL) 1357 return; 1358 w = lock->lo_witness; 1359 td = curthread; 1360 file = fixup_filename(file); 1361 1362 /* Determine lock list for this lock. */ 1363 if (LOCK_CLASS(lock)->lc_flags & LC_SLEEPLOCK) 1364 lock_list = &td->td_sleeplocks; 1365 else 1366 lock_list = PCPU_PTR(spinlocks); 1367 1368 /* Check to see if we are recursing on a lock we already own. */ 1369 instance = find_instance(*lock_list, lock); 1370 if (instance != NULL) { 1371 instance->li_flags++; 1372 CTR4(KTR_WITNESS, "%s: pid %d recursed on %s r=%d", __func__, 1373 td->td_proc->p_pid, lock->lo_name, 1374 instance->li_flags & LI_RECURSEMASK); 1375 instance->li_file = file; 1376 instance->li_line = line; 1377 return; 1378 } 1379 1380 /* Update per-witness last file and line acquire. */ 1381 w->w_file = file; 1382 w->w_line = line; 1383 1384 /* Find the next open lock instance in the list and fill it. */ 1385 lle = *lock_list; 1386 if (lle == NULL || lle->ll_count == LOCK_NCHILDREN) { 1387 lle = witness_lock_list_get(); 1388 if (lle == NULL) 1389 return; 1390 lle->ll_next = *lock_list; 1391 CTR3(KTR_WITNESS, "%s: pid %d added lle %p", __func__, 1392 td->td_proc->p_pid, lle); 1393 *lock_list = lle; 1394 } 1395 instance = &lle->ll_children[lle->ll_count++]; 1396 instance->li_lock = lock; 1397 instance->li_line = line; 1398 instance->li_file = file; 1399 if ((flags & LOP_EXCLUSIVE) != 0) 1400 instance->li_flags = LI_EXCLUSIVE; 1401 else 1402 instance->li_flags = 0; 1403 CTR4(KTR_WITNESS, "%s: pid %d added %s as lle[%d]", __func__, 1404 td->td_proc->p_pid, lock->lo_name, lle->ll_count - 1); 1405 } 1406 1407 void 1408 witness_upgrade(struct lock_object *lock, int flags, const char *file, int line) 1409 { 1410 struct lock_instance *instance; 1411 struct lock_class *class; 1412 1413 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); 1414 if (lock->lo_witness == NULL || witness_watch == -1 || panicstr != NULL) 1415 return; 1416 class = LOCK_CLASS(lock); 1417 file = fixup_filename(file); 1418 if (witness_watch) { 1419 if ((lock->lo_flags & LO_UPGRADABLE) == 0) 1420 panic("upgrade of non-upgradable lock (%s) %s @ %s:%d", 1421 class->lc_name, lock->lo_name, file, line); 1422 if ((class->lc_flags & LC_SLEEPLOCK) == 0) 1423 panic("upgrade of non-sleep lock (%s) %s @ %s:%d", 1424 class->lc_name, lock->lo_name, file, line); 1425 } 1426 instance = find_instance(curthread->td_sleeplocks, lock); 1427 if (instance == NULL) 1428 panic("upgrade of unlocked lock (%s) %s @ %s:%d", 1429 class->lc_name, lock->lo_name, file, line); 1430 if (witness_watch) { 1431 if ((instance->li_flags & LI_EXCLUSIVE) != 0) 1432 panic("upgrade of exclusive lock (%s) %s @ %s:%d", 1433 class->lc_name, lock->lo_name, file, line); 1434 if ((instance->li_flags & LI_RECURSEMASK) != 0) 1435 panic("upgrade of recursed lock (%s) %s r=%d @ %s:%d", 1436 class->lc_name, lock->lo_name, 1437 instance->li_flags & LI_RECURSEMASK, file, line); 1438 } 1439 instance->li_flags |= LI_EXCLUSIVE; 1440 } 1441 1442 void 1443 witness_downgrade(struct lock_object *lock, int flags, const char *file, 1444 int line) 1445 { 1446 struct lock_instance *instance; 1447 struct lock_class *class; 1448 1449 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); 1450 if (lock->lo_witness == NULL || witness_watch == -1 || panicstr != NULL) 1451 return; 1452 class = LOCK_CLASS(lock); 1453 file = fixup_filename(file); 1454 if (witness_watch) { 1455 if ((lock->lo_flags & LO_UPGRADABLE) == 0) 1456 panic("downgrade of non-upgradable lock (%s) %s @ %s:%d", 1457 class->lc_name, lock->lo_name, file, line); 1458 if ((class->lc_flags & LC_SLEEPLOCK) == 0) 1459 panic("downgrade of non-sleep lock (%s) %s @ %s:%d", 1460 class->lc_name, lock->lo_name, file, line); 1461 } 1462 instance = find_instance(curthread->td_sleeplocks, lock); 1463 if (instance == NULL) 1464 panic("downgrade of unlocked lock (%s) %s @ %s:%d", 1465 class->lc_name, lock->lo_name, file, line); 1466 if (witness_watch) { 1467 if ((instance->li_flags & LI_EXCLUSIVE) == 0) 1468 panic("downgrade of shared lock (%s) %s @ %s:%d", 1469 class->lc_name, lock->lo_name, file, line); 1470 if ((instance->li_flags & LI_RECURSEMASK) != 0) 1471 panic("downgrade of recursed lock (%s) %s r=%d @ %s:%d", 1472 class->lc_name, lock->lo_name, 1473 instance->li_flags & LI_RECURSEMASK, file, line); 1474 } 1475 instance->li_flags &= ~LI_EXCLUSIVE; 1476 } 1477 1478 void 1479 witness_unlock(struct lock_object *lock, int flags, const char *file, int line) 1480 { 1481 struct lock_list_entry **lock_list, *lle; 1482 struct lock_instance *instance; 1483 struct lock_class *class; 1484 struct thread *td; 1485 register_t s; 1486 int i, j; 1487 1488 if (witness_cold || lock->lo_witness == NULL || panicstr != NULL) 1489 return; 1490 td = curthread; 1491 class = LOCK_CLASS(lock); 1492 file = fixup_filename(file); 1493 1494 /* Find lock instance associated with this lock. */ 1495 if (class->lc_flags & LC_SLEEPLOCK) 1496 lock_list = &td->td_sleeplocks; 1497 else 1498 lock_list = PCPU_PTR(spinlocks); 1499 lle = *lock_list; 1500 for (; *lock_list != NULL; lock_list = &(*lock_list)->ll_next) 1501 for (i = 0; i < (*lock_list)->ll_count; i++) { 1502 instance = &(*lock_list)->ll_children[i]; 1503 if (instance->li_lock == lock) 1504 goto found; 1505 } 1506 1507 /* 1508 * When disabling WITNESS through witness_watch we could end up in 1509 * having registered locks in the td_sleeplocks queue. 1510 * We have to make sure we flush these queues, so just search for 1511 * eventual register locks and remove them. 1512 */ 1513 if (witness_watch > 0) 1514 panic("lock (%s) %s not locked @ %s:%d", class->lc_name, 1515 lock->lo_name, file, line); 1516 else 1517 return; 1518 found: 1519 1520 /* First, check for shared/exclusive mismatches. */ 1521 if ((instance->li_flags & LI_EXCLUSIVE) != 0 && witness_watch > 0 && 1522 (flags & LOP_EXCLUSIVE) == 0) { 1523 printf("shared unlock of (%s) %s @ %s:%d\n", class->lc_name, 1524 lock->lo_name, file, line); 1525 printf("while exclusively locked from %s:%d\n", 1526 instance->li_file, instance->li_line); 1527 panic("excl->ushare"); 1528 } 1529 if ((instance->li_flags & LI_EXCLUSIVE) == 0 && witness_watch > 0 && 1530 (flags & LOP_EXCLUSIVE) != 0) { 1531 printf("exclusive unlock of (%s) %s @ %s:%d\n", class->lc_name, 1532 lock->lo_name, file, line); 1533 printf("while share locked from %s:%d\n", instance->li_file, 1534 instance->li_line); 1535 panic("share->uexcl"); 1536 } 1537 /* If we are recursed, unrecurse. */ 1538 if ((instance->li_flags & LI_RECURSEMASK) > 0) { 1539 CTR4(KTR_WITNESS, "%s: pid %d unrecursed on %s r=%d", __func__, 1540 td->td_proc->p_pid, instance->li_lock->lo_name, 1541 instance->li_flags); 1542 instance->li_flags--; 1543 return; 1544 } 1545 /* The lock is now being dropped, check for NORELEASE flag */ 1546 if ((instance->li_flags & LI_NORELEASE) != 0 && witness_watch > 0) { 1547 printf("forbidden unlock of (%s) %s @ %s:%d\n", class->lc_name, 1548 lock->lo_name, file, line); 1549 panic("lock marked norelease"); 1550 } 1551 1552 /* Otherwise, remove this item from the list. */ 1553 s = intr_disable(); 1554 CTR4(KTR_WITNESS, "%s: pid %d removed %s from lle[%d]", __func__, 1555 td->td_proc->p_pid, instance->li_lock->lo_name, 1556 (*lock_list)->ll_count - 1); 1557 for (j = i; j < (*lock_list)->ll_count - 1; j++) 1558 (*lock_list)->ll_children[j] = 1559 (*lock_list)->ll_children[j + 1]; 1560 (*lock_list)->ll_count--; 1561 intr_restore(s); 1562 1563 /* 1564 * In order to reduce contention on w_mtx, we want to keep always an 1565 * head object into lists so that frequent allocation from the 1566 * free witness pool (and subsequent locking) is avoided. 1567 * In order to maintain the current code simple, when the head 1568 * object is totally unloaded it means also that we do not have 1569 * further objects in the list, so the list ownership needs to be 1570 * hand over to another object if the current head needs to be freed. 1571 */ 1572 if ((*lock_list)->ll_count == 0) { 1573 if (*lock_list == lle) { 1574 if (lle->ll_next == NULL) 1575 return; 1576 } else 1577 lle = *lock_list; 1578 *lock_list = lle->ll_next; 1579 CTR3(KTR_WITNESS, "%s: pid %d removed lle %p", __func__, 1580 td->td_proc->p_pid, lle); 1581 witness_lock_list_free(lle); 1582 } 1583 } 1584 1585 void 1586 witness_thread_exit(struct thread *td) 1587 { 1588 struct lock_list_entry *lle; 1589 int i, n; 1590 1591 lle = td->td_sleeplocks; 1592 if (lle == NULL || panicstr != NULL) 1593 return; 1594 if (lle->ll_count != 0) { 1595 for (n = 0; lle != NULL; lle = lle->ll_next) 1596 for (i = lle->ll_count - 1; i >= 0; i--) { 1597 if (n == 0) 1598 printf("Thread %p exiting with the following locks held:\n", 1599 td); 1600 n++; 1601 witness_list_lock(&lle->ll_children[i], printf); 1602 1603 } 1604 panic("Thread %p cannot exit while holding sleeplocks\n", td); 1605 } 1606 witness_lock_list_free(lle); 1607 } 1608 1609 /* 1610 * Warn if any locks other than 'lock' are held. Flags can be passed in to 1611 * exempt Giant and sleepable locks from the checks as well. If any 1612 * non-exempt locks are held, then a supplied message is printed to the 1613 * console along with a list of the offending locks. If indicated in the 1614 * flags then a failure results in a panic as well. 1615 */ 1616 int 1617 witness_warn(int flags, struct lock_object *lock, const char *fmt, ...) 1618 { 1619 struct lock_list_entry *lock_list, *lle; 1620 struct lock_instance *lock1; 1621 struct thread *td; 1622 va_list ap; 1623 int i, n; 1624 1625 if (witness_cold || witness_watch < 1 || panicstr != NULL) 1626 return (0); 1627 n = 0; 1628 td = curthread; 1629 for (lle = td->td_sleeplocks; lle != NULL; lle = lle->ll_next) 1630 for (i = lle->ll_count - 1; i >= 0; i--) { 1631 lock1 = &lle->ll_children[i]; 1632 if (lock1->li_lock == lock) 1633 continue; 1634 if (flags & WARN_GIANTOK && 1635 lock1->li_lock == &Giant.lock_object) 1636 continue; 1637 if (flags & WARN_SLEEPOK && 1638 (lock1->li_lock->lo_flags & LO_SLEEPABLE) != 0) 1639 continue; 1640 if (n == 0) { 1641 va_start(ap, fmt); 1642 vprintf(fmt, ap); 1643 va_end(ap); 1644 printf(" with the following"); 1645 if (flags & WARN_SLEEPOK) 1646 printf(" non-sleepable"); 1647 printf(" locks held:\n"); 1648 } 1649 n++; 1650 witness_list_lock(lock1, printf); 1651 } 1652 1653 /* 1654 * Pin the thread in order to avoid problems with thread migration. 1655 * Once that all verifies are passed about spinlocks ownership, 1656 * the thread is in a safe path and it can be unpinned. 1657 */ 1658 sched_pin(); 1659 lock_list = PCPU_GET(spinlocks); 1660 if (lock_list != NULL && lock_list->ll_count != 0) { 1661 sched_unpin(); 1662 1663 /* 1664 * We should only have one spinlock and as long as 1665 * the flags cannot match for this locks class, 1666 * check if the first spinlock is the one curthread 1667 * should hold. 1668 */ 1669 lock1 = &lock_list->ll_children[lock_list->ll_count - 1]; 1670 if (lock_list->ll_count == 1 && lock_list->ll_next == NULL && 1671 lock1->li_lock == lock && n == 0) 1672 return (0); 1673 1674 va_start(ap, fmt); 1675 vprintf(fmt, ap); 1676 va_end(ap); 1677 printf(" with the following"); 1678 if (flags & WARN_SLEEPOK) 1679 printf(" non-sleepable"); 1680 printf(" locks held:\n"); 1681 n += witness_list_locks(&lock_list, printf); 1682 } else 1683 sched_unpin(); 1684 if (flags & WARN_PANIC && n) 1685 panic("%s", __func__); 1686 else 1687 witness_debugger(n); 1688 return (n); 1689 } 1690 1691 const char * 1692 witness_file(struct lock_object *lock) 1693 { 1694 struct witness *w; 1695 1696 if (witness_cold || witness_watch < 1 || lock->lo_witness == NULL) 1697 return ("?"); 1698 w = lock->lo_witness; 1699 return (w->w_file); 1700 } 1701 1702 int 1703 witness_line(struct lock_object *lock) 1704 { 1705 struct witness *w; 1706 1707 if (witness_cold || witness_watch < 1 || lock->lo_witness == NULL) 1708 return (0); 1709 w = lock->lo_witness; 1710 return (w->w_line); 1711 } 1712 1713 static struct witness * 1714 enroll(const char *description, struct lock_class *lock_class) 1715 { 1716 struct witness *w; 1717 struct witness_list *typelist; 1718 1719 MPASS(description != NULL); 1720 1721 if (witness_watch == -1 || panicstr != NULL) 1722 return (NULL); 1723 if ((lock_class->lc_flags & LC_SPINLOCK)) { 1724 if (witness_skipspin) 1725 return (NULL); 1726 else 1727 typelist = &w_spin; 1728 } else if ((lock_class->lc_flags & LC_SLEEPLOCK)) 1729 typelist = &w_sleep; 1730 else 1731 panic("lock class %s is not sleep or spin", 1732 lock_class->lc_name); 1733 1734 mtx_lock_spin(&w_mtx); 1735 w = witness_hash_get(description); 1736 if (w) 1737 goto found; 1738 if ((w = witness_get()) == NULL) 1739 return (NULL); 1740 MPASS(strlen(description) < MAX_W_NAME); 1741 strcpy(w->w_name, description); 1742 w->w_class = lock_class; 1743 w->w_refcount = 1; 1744 STAILQ_INSERT_HEAD(&w_all, w, w_list); 1745 if (lock_class->lc_flags & LC_SPINLOCK) { 1746 STAILQ_INSERT_HEAD(&w_spin, w, w_typelist); 1747 w_spin_cnt++; 1748 } else if (lock_class->lc_flags & LC_SLEEPLOCK) { 1749 STAILQ_INSERT_HEAD(&w_sleep, w, w_typelist); 1750 w_sleep_cnt++; 1751 } 1752 1753 /* Insert new witness into the hash */ 1754 witness_hash_put(w); 1755 witness_increment_graph_generation(); 1756 mtx_unlock_spin(&w_mtx); 1757 return (w); 1758 found: 1759 w->w_refcount++; 1760 mtx_unlock_spin(&w_mtx); 1761 if (lock_class != w->w_class) 1762 panic( 1763 "lock (%s) %s does not match earlier (%s) lock", 1764 description, lock_class->lc_name, 1765 w->w_class->lc_name); 1766 return (w); 1767 } 1768 1769 static void 1770 depart(struct witness *w) 1771 { 1772 struct witness_list *list; 1773 1774 MPASS(w->w_refcount == 0); 1775 if (w->w_class->lc_flags & LC_SLEEPLOCK) { 1776 list = &w_sleep; 1777 w_sleep_cnt--; 1778 } else { 1779 list = &w_spin; 1780 w_spin_cnt--; 1781 } 1782 /* 1783 * Set file to NULL as it may point into a loadable module. 1784 */ 1785 w->w_file = NULL; 1786 w->w_line = 0; 1787 witness_increment_graph_generation(); 1788 } 1789 1790 1791 static void 1792 adopt(struct witness *parent, struct witness *child) 1793 { 1794 int pi, ci, i, j; 1795 1796 if (witness_cold == 0) 1797 mtx_assert(&w_mtx, MA_OWNED); 1798 1799 /* If the relationship is already known, there's no work to be done. */ 1800 if (isitmychild(parent, child)) 1801 return; 1802 1803 /* When the structure of the graph changes, bump up the generation. */ 1804 witness_increment_graph_generation(); 1805 1806 /* 1807 * The hard part ... create the direct relationship, then propagate all 1808 * indirect relationships. 1809 */ 1810 pi = parent->w_index; 1811 ci = child->w_index; 1812 WITNESS_INDEX_ASSERT(pi); 1813 WITNESS_INDEX_ASSERT(ci); 1814 MPASS(pi != ci); 1815 w_rmatrix[pi][ci] |= WITNESS_PARENT; 1816 w_rmatrix[ci][pi] |= WITNESS_CHILD; 1817 1818 /* 1819 * If parent was not already an ancestor of child, 1820 * then we increment the descendant and ancestor counters. 1821 */ 1822 if ((w_rmatrix[pi][ci] & WITNESS_ANCESTOR) == 0) { 1823 parent->w_num_descendants++; 1824 child->w_num_ancestors++; 1825 } 1826 1827 /* 1828 * Find each ancestor of 'pi'. Note that 'pi' itself is counted as 1829 * an ancestor of 'pi' during this loop. 1830 */ 1831 for (i = 1; i <= w_max_used_index; i++) { 1832 if ((w_rmatrix[i][pi] & WITNESS_ANCESTOR_MASK) == 0 && 1833 (i != pi)) 1834 continue; 1835 1836 /* Find each descendant of 'i' and mark it as a descendant. */ 1837 for (j = 1; j <= w_max_used_index; j++) { 1838 1839 /* 1840 * Skip children that are already marked as 1841 * descendants of 'i'. 1842 */ 1843 if (w_rmatrix[i][j] & WITNESS_ANCESTOR_MASK) 1844 continue; 1845 1846 /* 1847 * We are only interested in descendants of 'ci'. Note 1848 * that 'ci' itself is counted as a descendant of 'ci'. 1849 */ 1850 if ((w_rmatrix[ci][j] & WITNESS_ANCESTOR_MASK) == 0 && 1851 (j != ci)) 1852 continue; 1853 w_rmatrix[i][j] |= WITNESS_ANCESTOR; 1854 w_rmatrix[j][i] |= WITNESS_DESCENDANT; 1855 w_data[i].w_num_descendants++; 1856 w_data[j].w_num_ancestors++; 1857 1858 /* 1859 * Make sure we aren't marking a node as both an 1860 * ancestor and descendant. We should have caught 1861 * this as a lock order reversal earlier. 1862 */ 1863 if ((w_rmatrix[i][j] & WITNESS_ANCESTOR_MASK) && 1864 (w_rmatrix[i][j] & WITNESS_DESCENDANT_MASK)) { 1865 printf("witness rmatrix paradox! [%d][%d]=%d " 1866 "both ancestor and descendant\n", 1867 i, j, w_rmatrix[i][j]); 1868 kdb_backtrace(); 1869 printf("Witness disabled.\n"); 1870 witness_watch = -1; 1871 } 1872 if ((w_rmatrix[j][i] & WITNESS_ANCESTOR_MASK) && 1873 (w_rmatrix[j][i] & WITNESS_DESCENDANT_MASK)) { 1874 printf("witness rmatrix paradox! [%d][%d]=%d " 1875 "both ancestor and descendant\n", 1876 j, i, w_rmatrix[j][i]); 1877 kdb_backtrace(); 1878 printf("Witness disabled.\n"); 1879 witness_watch = -1; 1880 } 1881 } 1882 } 1883 } 1884 1885 static void 1886 itismychild(struct witness *parent, struct witness *child) 1887 { 1888 1889 MPASS(child != NULL && parent != NULL); 1890 if (witness_cold == 0) 1891 mtx_assert(&w_mtx, MA_OWNED); 1892 1893 if (!witness_lock_type_equal(parent, child)) { 1894 if (witness_cold == 0) 1895 mtx_unlock_spin(&w_mtx); 1896 panic("%s: parent \"%s\" (%s) and child \"%s\" (%s) are not " 1897 "the same lock type", __func__, parent->w_name, 1898 parent->w_class->lc_name, child->w_name, 1899 child->w_class->lc_name); 1900 } 1901 adopt(parent, child); 1902 } 1903 1904 /* 1905 * Generic code for the isitmy*() functions. The rmask parameter is the 1906 * expected relationship of w1 to w2. 1907 */ 1908 static int 1909 _isitmyx(struct witness *w1, struct witness *w2, int rmask, const char *fname) 1910 { 1911 unsigned char r1, r2; 1912 int i1, i2; 1913 1914 i1 = w1->w_index; 1915 i2 = w2->w_index; 1916 WITNESS_INDEX_ASSERT(i1); 1917 WITNESS_INDEX_ASSERT(i2); 1918 r1 = w_rmatrix[i1][i2] & WITNESS_RELATED_MASK; 1919 r2 = w_rmatrix[i2][i1] & WITNESS_RELATED_MASK; 1920 1921 /* The flags on one better be the inverse of the flags on the other */ 1922 if (!((WITNESS_ATOD(r1) == r2 && WITNESS_DTOA(r2) == r1) || 1923 (WITNESS_DTOA(r1) == r2 && WITNESS_ATOD(r2) == r1))) { 1924 printf("%s: rmatrix mismatch between %s (index %d) and %s " 1925 "(index %d): w_rmatrix[%d][%d] == %hhx but " 1926 "w_rmatrix[%d][%d] == %hhx\n", 1927 fname, w1->w_name, i1, w2->w_name, i2, i1, i2, r1, 1928 i2, i1, r2); 1929 kdb_backtrace(); 1930 printf("Witness disabled.\n"); 1931 witness_watch = -1; 1932 } 1933 return (r1 & rmask); 1934 } 1935 1936 /* 1937 * Checks if @child is a direct child of @parent. 1938 */ 1939 static int 1940 isitmychild(struct witness *parent, struct witness *child) 1941 { 1942 1943 return (_isitmyx(parent, child, WITNESS_PARENT, __func__)); 1944 } 1945 1946 /* 1947 * Checks if @descendant is a direct or inderect descendant of @ancestor. 1948 */ 1949 static int 1950 isitmydescendant(struct witness *ancestor, struct witness *descendant) 1951 { 1952 1953 return (_isitmyx(ancestor, descendant, WITNESS_ANCESTOR_MASK, 1954 __func__)); 1955 } 1956 1957 #ifdef BLESSING 1958 static int 1959 blessed(struct witness *w1, struct witness *w2) 1960 { 1961 int i; 1962 struct witness_blessed *b; 1963 1964 for (i = 0; i < blessed_count; i++) { 1965 b = &blessed_list[i]; 1966 if (strcmp(w1->w_name, b->b_lock1) == 0) { 1967 if (strcmp(w2->w_name, b->b_lock2) == 0) 1968 return (1); 1969 continue; 1970 } 1971 if (strcmp(w1->w_name, b->b_lock2) == 0) 1972 if (strcmp(w2->w_name, b->b_lock1) == 0) 1973 return (1); 1974 } 1975 return (0); 1976 } 1977 #endif 1978 1979 static struct witness * 1980 witness_get(void) 1981 { 1982 struct witness *w; 1983 int index; 1984 1985 if (witness_cold == 0) 1986 mtx_assert(&w_mtx, MA_OWNED); 1987 1988 if (witness_watch == -1) { 1989 mtx_unlock_spin(&w_mtx); 1990 return (NULL); 1991 } 1992 if (STAILQ_EMPTY(&w_free)) { 1993 witness_watch = -1; 1994 mtx_unlock_spin(&w_mtx); 1995 printf("WITNESS: unable to allocate a new witness object\n"); 1996 return (NULL); 1997 } 1998 w = STAILQ_FIRST(&w_free); 1999 STAILQ_REMOVE_HEAD(&w_free, w_list); 2000 w_free_cnt--; 2001 index = w->w_index; 2002 MPASS(index > 0 && index == w_max_used_index+1 && 2003 index < WITNESS_COUNT); 2004 bzero(w, sizeof(*w)); 2005 w->w_index = index; 2006 if (index > w_max_used_index) 2007 w_max_used_index = index; 2008 return (w); 2009 } 2010 2011 static void 2012 witness_free(struct witness *w) 2013 { 2014 2015 STAILQ_INSERT_HEAD(&w_free, w, w_list); 2016 w_free_cnt++; 2017 } 2018 2019 static struct lock_list_entry * 2020 witness_lock_list_get(void) 2021 { 2022 struct lock_list_entry *lle; 2023 2024 if (witness_watch == -1) 2025 return (NULL); 2026 mtx_lock_spin(&w_mtx); 2027 lle = w_lock_list_free; 2028 if (lle == NULL) { 2029 witness_watch = -1; 2030 mtx_unlock_spin(&w_mtx); 2031 printf("%s: witness exhausted\n", __func__); 2032 return (NULL); 2033 } 2034 w_lock_list_free = lle->ll_next; 2035 mtx_unlock_spin(&w_mtx); 2036 bzero(lle, sizeof(*lle)); 2037 return (lle); 2038 } 2039 2040 static void 2041 witness_lock_list_free(struct lock_list_entry *lle) 2042 { 2043 2044 mtx_lock_spin(&w_mtx); 2045 lle->ll_next = w_lock_list_free; 2046 w_lock_list_free = lle; 2047 mtx_unlock_spin(&w_mtx); 2048 } 2049 2050 static struct lock_instance * 2051 find_instance(struct lock_list_entry *list, struct lock_object *lock) 2052 { 2053 struct lock_list_entry *lle; 2054 struct lock_instance *instance; 2055 int i; 2056 2057 for (lle = list; lle != NULL; lle = lle->ll_next) 2058 for (i = lle->ll_count - 1; i >= 0; i--) { 2059 instance = &lle->ll_children[i]; 2060 if (instance->li_lock == lock) 2061 return (instance); 2062 } 2063 return (NULL); 2064 } 2065 2066 static void 2067 witness_list_lock(struct lock_instance *instance, 2068 int (*prnt)(const char *fmt, ...)) 2069 { 2070 struct lock_object *lock; 2071 2072 lock = instance->li_lock; 2073 prnt("%s %s %s", (instance->li_flags & LI_EXCLUSIVE) != 0 ? 2074 "exclusive" : "shared", LOCK_CLASS(lock)->lc_name, lock->lo_name); 2075 if (lock->lo_witness->w_name != lock->lo_name) 2076 prnt(" (%s)", lock->lo_witness->w_name); 2077 prnt(" r = %d (%p) locked @ %s:%d\n", 2078 instance->li_flags & LI_RECURSEMASK, lock, instance->li_file, 2079 instance->li_line); 2080 } 2081 2082 #ifdef DDB 2083 static int 2084 witness_thread_has_locks(struct thread *td) 2085 { 2086 2087 if (td->td_sleeplocks == NULL) 2088 return (0); 2089 return (td->td_sleeplocks->ll_count != 0); 2090 } 2091 2092 static int 2093 witness_proc_has_locks(struct proc *p) 2094 { 2095 struct thread *td; 2096 2097 FOREACH_THREAD_IN_PROC(p, td) { 2098 if (witness_thread_has_locks(td)) 2099 return (1); 2100 } 2101 return (0); 2102 } 2103 #endif 2104 2105 int 2106 witness_list_locks(struct lock_list_entry **lock_list, 2107 int (*prnt)(const char *fmt, ...)) 2108 { 2109 struct lock_list_entry *lle; 2110 int i, nheld; 2111 2112 nheld = 0; 2113 for (lle = *lock_list; lle != NULL; lle = lle->ll_next) 2114 for (i = lle->ll_count - 1; i >= 0; i--) { 2115 witness_list_lock(&lle->ll_children[i], prnt); 2116 nheld++; 2117 } 2118 return (nheld); 2119 } 2120 2121 /* 2122 * This is a bit risky at best. We call this function when we have timed 2123 * out acquiring a spin lock, and we assume that the other CPU is stuck 2124 * with this lock held. So, we go groveling around in the other CPU's 2125 * per-cpu data to try to find the lock instance for this spin lock to 2126 * see when it was last acquired. 2127 */ 2128 void 2129 witness_display_spinlock(struct lock_object *lock, struct thread *owner, 2130 int (*prnt)(const char *fmt, ...)) 2131 { 2132 struct lock_instance *instance; 2133 struct pcpu *pc; 2134 2135 if (owner->td_critnest == 0 || owner->td_oncpu == NOCPU) 2136 return; 2137 pc = pcpu_find(owner->td_oncpu); 2138 instance = find_instance(pc->pc_spinlocks, lock); 2139 if (instance != NULL) 2140 witness_list_lock(instance, prnt); 2141 } 2142 2143 void 2144 witness_save(struct lock_object *lock, const char **filep, int *linep) 2145 { 2146 struct lock_list_entry *lock_list; 2147 struct lock_instance *instance; 2148 struct lock_class *class; 2149 2150 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); 2151 if (lock->lo_witness == NULL || witness_watch == -1 || panicstr != NULL) 2152 return; 2153 class = LOCK_CLASS(lock); 2154 if (class->lc_flags & LC_SLEEPLOCK) 2155 lock_list = curthread->td_sleeplocks; 2156 else { 2157 if (witness_skipspin) 2158 return; 2159 lock_list = PCPU_GET(spinlocks); 2160 } 2161 instance = find_instance(lock_list, lock); 2162 if (instance == NULL) 2163 panic("%s: lock (%s) %s not locked", __func__, 2164 class->lc_name, lock->lo_name); 2165 *filep = instance->li_file; 2166 *linep = instance->li_line; 2167 } 2168 2169 void 2170 witness_restore(struct lock_object *lock, const char *file, int line) 2171 { 2172 struct lock_list_entry *lock_list; 2173 struct lock_instance *instance; 2174 struct lock_class *class; 2175 2176 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); 2177 if (lock->lo_witness == NULL || witness_watch == -1 || panicstr != NULL) 2178 return; 2179 class = LOCK_CLASS(lock); 2180 if (class->lc_flags & LC_SLEEPLOCK) 2181 lock_list = curthread->td_sleeplocks; 2182 else { 2183 if (witness_skipspin) 2184 return; 2185 lock_list = PCPU_GET(spinlocks); 2186 } 2187 instance = find_instance(lock_list, lock); 2188 if (instance == NULL) 2189 panic("%s: lock (%s) %s not locked", __func__, 2190 class->lc_name, lock->lo_name); 2191 lock->lo_witness->w_file = file; 2192 lock->lo_witness->w_line = line; 2193 instance->li_file = file; 2194 instance->li_line = line; 2195 } 2196 2197 void 2198 witness_assert(struct lock_object *lock, int flags, const char *file, int line) 2199 { 2200 #ifdef INVARIANT_SUPPORT 2201 struct lock_instance *instance; 2202 struct lock_class *class; 2203 2204 if (lock->lo_witness == NULL || witness_watch < 1 || panicstr != NULL) 2205 return; 2206 class = LOCK_CLASS(lock); 2207 if ((class->lc_flags & LC_SLEEPLOCK) != 0) 2208 instance = find_instance(curthread->td_sleeplocks, lock); 2209 else if ((class->lc_flags & LC_SPINLOCK) != 0) 2210 instance = find_instance(PCPU_GET(spinlocks), lock); 2211 else { 2212 panic("Lock (%s) %s is not sleep or spin!", 2213 class->lc_name, lock->lo_name); 2214 } 2215 file = fixup_filename(file); 2216 switch (flags) { 2217 case LA_UNLOCKED: 2218 if (instance != NULL) 2219 panic("Lock (%s) %s locked @ %s:%d.", 2220 class->lc_name, lock->lo_name, file, line); 2221 break; 2222 case LA_LOCKED: 2223 case LA_LOCKED | LA_RECURSED: 2224 case LA_LOCKED | LA_NOTRECURSED: 2225 case LA_SLOCKED: 2226 case LA_SLOCKED | LA_RECURSED: 2227 case LA_SLOCKED | LA_NOTRECURSED: 2228 case LA_XLOCKED: 2229 case LA_XLOCKED | LA_RECURSED: 2230 case LA_XLOCKED | LA_NOTRECURSED: 2231 if (instance == NULL) { 2232 panic("Lock (%s) %s not locked @ %s:%d.", 2233 class->lc_name, lock->lo_name, file, line); 2234 break; 2235 } 2236 if ((flags & LA_XLOCKED) != 0 && 2237 (instance->li_flags & LI_EXCLUSIVE) == 0) 2238 panic("Lock (%s) %s not exclusively locked @ %s:%d.", 2239 class->lc_name, lock->lo_name, file, line); 2240 if ((flags & LA_SLOCKED) != 0 && 2241 (instance->li_flags & LI_EXCLUSIVE) != 0) 2242 panic("Lock (%s) %s exclusively locked @ %s:%d.", 2243 class->lc_name, lock->lo_name, file, line); 2244 if ((flags & LA_RECURSED) != 0 && 2245 (instance->li_flags & LI_RECURSEMASK) == 0) 2246 panic("Lock (%s) %s not recursed @ %s:%d.", 2247 class->lc_name, lock->lo_name, file, line); 2248 if ((flags & LA_NOTRECURSED) != 0 && 2249 (instance->li_flags & LI_RECURSEMASK) != 0) 2250 panic("Lock (%s) %s recursed @ %s:%d.", 2251 class->lc_name, lock->lo_name, file, line); 2252 break; 2253 default: 2254 panic("Invalid lock assertion at %s:%d.", file, line); 2255 2256 } 2257 #endif /* INVARIANT_SUPPORT */ 2258 } 2259 2260 static void 2261 witness_setflag(struct lock_object *lock, int flag, int set) 2262 { 2263 struct lock_list_entry *lock_list; 2264 struct lock_instance *instance; 2265 struct lock_class *class; 2266 2267 if (lock->lo_witness == NULL || witness_watch == -1 || panicstr != NULL) 2268 return; 2269 class = LOCK_CLASS(lock); 2270 if (class->lc_flags & LC_SLEEPLOCK) 2271 lock_list = curthread->td_sleeplocks; 2272 else { 2273 if (witness_skipspin) 2274 return; 2275 lock_list = PCPU_GET(spinlocks); 2276 } 2277 instance = find_instance(lock_list, lock); 2278 if (instance == NULL) 2279 panic("%s: lock (%s) %s not locked", __func__, 2280 class->lc_name, lock->lo_name); 2281 2282 if (set) 2283 instance->li_flags |= flag; 2284 else 2285 instance->li_flags &= ~flag; 2286 } 2287 2288 void 2289 witness_norelease(struct lock_object *lock) 2290 { 2291 2292 witness_setflag(lock, LI_NORELEASE, 1); 2293 } 2294 2295 void 2296 witness_releaseok(struct lock_object *lock) 2297 { 2298 2299 witness_setflag(lock, LI_NORELEASE, 0); 2300 } 2301 2302 #ifdef DDB 2303 static void 2304 witness_ddb_list(struct thread *td) 2305 { 2306 2307 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); 2308 KASSERT(kdb_active, ("%s: not in the debugger", __func__)); 2309 2310 if (witness_watch < 1) 2311 return; 2312 2313 witness_list_locks(&td->td_sleeplocks, db_printf); 2314 2315 /* 2316 * We only handle spinlocks if td == curthread. This is somewhat broken 2317 * if td is currently executing on some other CPU and holds spin locks 2318 * as we won't display those locks. If we had a MI way of getting 2319 * the per-cpu data for a given cpu then we could use 2320 * td->td_oncpu to get the list of spinlocks for this thread 2321 * and "fix" this. 2322 * 2323 * That still wouldn't really fix this unless we locked the scheduler 2324 * lock or stopped the other CPU to make sure it wasn't changing the 2325 * list out from under us. It is probably best to just not try to 2326 * handle threads on other CPU's for now. 2327 */ 2328 if (td == curthread && PCPU_GET(spinlocks) != NULL) 2329 witness_list_locks(PCPU_PTR(spinlocks), db_printf); 2330 } 2331 2332 DB_SHOW_COMMAND(locks, db_witness_list) 2333 { 2334 struct thread *td; 2335 2336 if (have_addr) 2337 td = db_lookup_thread(addr, TRUE); 2338 else 2339 td = kdb_thread; 2340 witness_ddb_list(td); 2341 } 2342 2343 DB_SHOW_ALL_COMMAND(locks, db_witness_list_all) 2344 { 2345 struct thread *td; 2346 struct proc *p; 2347 2348 /* 2349 * It would be nice to list only threads and processes that actually 2350 * held sleep locks, but that information is currently not exported 2351 * by WITNESS. 2352 */ 2353 FOREACH_PROC_IN_SYSTEM(p) { 2354 if (!witness_proc_has_locks(p)) 2355 continue; 2356 FOREACH_THREAD_IN_PROC(p, td) { 2357 if (!witness_thread_has_locks(td)) 2358 continue; 2359 db_printf("Process %d (%s) thread %p (%d)\n", p->p_pid, 2360 p->p_comm, td, td->td_tid); 2361 witness_ddb_list(td); 2362 } 2363 } 2364 } 2365 DB_SHOW_ALIAS(alllocks, db_witness_list_all) 2366 2367 DB_SHOW_COMMAND(witness, db_witness_display) 2368 { 2369 2370 witness_ddb_display(db_printf); 2371 } 2372 #endif 2373 2374 static int 2375 sysctl_debug_witness_badstacks(SYSCTL_HANDLER_ARGS) 2376 { 2377 struct witness_lock_order_data *data1, *data2, *tmp_data1, *tmp_data2; 2378 struct witness *tmp_w1, *tmp_w2, *w1, *w2; 2379 struct sbuf *sb; 2380 u_int w_rmatrix1, w_rmatrix2; 2381 int error, generation, i, j; 2382 2383 tmp_data1 = NULL; 2384 tmp_data2 = NULL; 2385 tmp_w1 = NULL; 2386 tmp_w2 = NULL; 2387 if (witness_watch < 1) { 2388 error = SYSCTL_OUT(req, w_notrunning, sizeof(w_notrunning)); 2389 return (error); 2390 } 2391 if (witness_cold) { 2392 error = SYSCTL_OUT(req, w_stillcold, sizeof(w_stillcold)); 2393 return (error); 2394 } 2395 error = 0; 2396 sb = sbuf_new(NULL, NULL, BADSTACK_SBUF_SIZE, SBUF_AUTOEXTEND); 2397 if (sb == NULL) 2398 return (ENOMEM); 2399 2400 /* Allocate and init temporary storage space. */ 2401 tmp_w1 = malloc(sizeof(struct witness), M_TEMP, M_WAITOK | M_ZERO); 2402 tmp_w2 = malloc(sizeof(struct witness), M_TEMP, M_WAITOK | M_ZERO); 2403 tmp_data1 = malloc(sizeof(struct witness_lock_order_data), M_TEMP, 2404 M_WAITOK | M_ZERO); 2405 tmp_data2 = malloc(sizeof(struct witness_lock_order_data), M_TEMP, 2406 M_WAITOK | M_ZERO); 2407 stack_zero(&tmp_data1->wlod_stack); 2408 stack_zero(&tmp_data2->wlod_stack); 2409 2410 restart: 2411 mtx_lock_spin(&w_mtx); 2412 generation = w_generation; 2413 mtx_unlock_spin(&w_mtx); 2414 sbuf_printf(sb, "Number of known direct relationships is %d\n", 2415 w_lohash.wloh_count); 2416 for (i = 1; i < w_max_used_index; i++) { 2417 mtx_lock_spin(&w_mtx); 2418 if (generation != w_generation) { 2419 mtx_unlock_spin(&w_mtx); 2420 2421 /* The graph has changed, try again. */ 2422 req->oldidx = 0; 2423 sbuf_clear(sb); 2424 goto restart; 2425 } 2426 2427 w1 = &w_data[i]; 2428 if (w1->w_reversed == 0) { 2429 mtx_unlock_spin(&w_mtx); 2430 continue; 2431 } 2432 2433 /* Copy w1 locally so we can release the spin lock. */ 2434 *tmp_w1 = *w1; 2435 mtx_unlock_spin(&w_mtx); 2436 2437 if (tmp_w1->w_reversed == 0) 2438 continue; 2439 for (j = 1; j < w_max_used_index; j++) { 2440 if ((w_rmatrix[i][j] & WITNESS_REVERSAL) == 0 || i > j) 2441 continue; 2442 2443 mtx_lock_spin(&w_mtx); 2444 if (generation != w_generation) { 2445 mtx_unlock_spin(&w_mtx); 2446 2447 /* The graph has changed, try again. */ 2448 req->oldidx = 0; 2449 sbuf_clear(sb); 2450 goto restart; 2451 } 2452 2453 w2 = &w_data[j]; 2454 data1 = witness_lock_order_get(w1, w2); 2455 data2 = witness_lock_order_get(w2, w1); 2456 2457 /* 2458 * Copy information locally so we can release the 2459 * spin lock. 2460 */ 2461 *tmp_w2 = *w2; 2462 w_rmatrix1 = (unsigned int)w_rmatrix[i][j]; 2463 w_rmatrix2 = (unsigned int)w_rmatrix[j][i]; 2464 2465 if (data1) { 2466 stack_zero(&tmp_data1->wlod_stack); 2467 stack_copy(&data1->wlod_stack, 2468 &tmp_data1->wlod_stack); 2469 } 2470 if (data2 && data2 != data1) { 2471 stack_zero(&tmp_data2->wlod_stack); 2472 stack_copy(&data2->wlod_stack, 2473 &tmp_data2->wlod_stack); 2474 } 2475 mtx_unlock_spin(&w_mtx); 2476 2477 sbuf_printf(sb, 2478 "\nLock order reversal between \"%s\"(%s) and \"%s\"(%s)!\n", 2479 tmp_w1->w_name, tmp_w1->w_class->lc_name, 2480 tmp_w2->w_name, tmp_w2->w_class->lc_name); 2481 #if 0 2482 sbuf_printf(sb, 2483 "w_rmatrix[%s][%s] == %x, w_rmatrix[%s][%s] == %x\n", 2484 tmp_w1->name, tmp_w2->w_name, w_rmatrix1, 2485 tmp_w2->name, tmp_w1->w_name, w_rmatrix2); 2486 #endif 2487 if (data1) { 2488 sbuf_printf(sb, 2489 "Lock order \"%s\"(%s) -> \"%s\"(%s) first seen at:\n", 2490 tmp_w1->w_name, tmp_w1->w_class->lc_name, 2491 tmp_w2->w_name, tmp_w2->w_class->lc_name); 2492 stack_sbuf_print(sb, &tmp_data1->wlod_stack); 2493 sbuf_printf(sb, "\n"); 2494 } 2495 if (data2 && data2 != data1) { 2496 sbuf_printf(sb, 2497 "Lock order \"%s\"(%s) -> \"%s\"(%s) first seen at:\n", 2498 tmp_w2->w_name, tmp_w2->w_class->lc_name, 2499 tmp_w1->w_name, tmp_w1->w_class->lc_name); 2500 stack_sbuf_print(sb, &tmp_data2->wlod_stack); 2501 sbuf_printf(sb, "\n"); 2502 } 2503 } 2504 } 2505 mtx_lock_spin(&w_mtx); 2506 if (generation != w_generation) { 2507 mtx_unlock_spin(&w_mtx); 2508 2509 /* 2510 * The graph changed while we were printing stack data, 2511 * try again. 2512 */ 2513 req->oldidx = 0; 2514 sbuf_clear(sb); 2515 goto restart; 2516 } 2517 mtx_unlock_spin(&w_mtx); 2518 2519 /* Free temporary storage space. */ 2520 free(tmp_data1, M_TEMP); 2521 free(tmp_data2, M_TEMP); 2522 free(tmp_w1, M_TEMP); 2523 free(tmp_w2, M_TEMP); 2524 2525 sbuf_finish(sb); 2526 error = SYSCTL_OUT(req, sbuf_data(sb), sbuf_len(sb) + 1); 2527 sbuf_delete(sb); 2528 2529 return (error); 2530 } 2531 2532 static int 2533 sysctl_debug_witness_fullgraph(SYSCTL_HANDLER_ARGS) 2534 { 2535 struct witness *w; 2536 struct sbuf *sb; 2537 int error; 2538 2539 if (witness_watch < 1) { 2540 error = SYSCTL_OUT(req, w_notrunning, sizeof(w_notrunning)); 2541 return (error); 2542 } 2543 if (witness_cold) { 2544 error = SYSCTL_OUT(req, w_stillcold, sizeof(w_stillcold)); 2545 return (error); 2546 } 2547 error = 0; 2548 sb = sbuf_new(NULL, NULL, FULLGRAPH_SBUF_SIZE, SBUF_FIXEDLEN); 2549 if (sb == NULL) 2550 return (ENOMEM); 2551 sbuf_printf(sb, "\n"); 2552 2553 mtx_lock_spin(&w_mtx); 2554 STAILQ_FOREACH(w, &w_all, w_list) 2555 w->w_displayed = 0; 2556 STAILQ_FOREACH(w, &w_all, w_list) 2557 witness_add_fullgraph(sb, w); 2558 mtx_unlock_spin(&w_mtx); 2559 2560 /* 2561 * While using SBUF_FIXEDLEN, check if the sbuf overflowed. 2562 */ 2563 if (sbuf_overflowed(sb)) { 2564 sbuf_delete(sb); 2565 panic("%s: sbuf overflowed, bump FULLGRAPH_SBUF_SIZE value\n", 2566 __func__); 2567 } 2568 2569 /* 2570 * Close the sbuf and return to userland. 2571 */ 2572 sbuf_finish(sb); 2573 error = SYSCTL_OUT(req, sbuf_data(sb), sbuf_len(sb) + 1); 2574 sbuf_delete(sb); 2575 2576 return (error); 2577 } 2578 2579 static int 2580 sysctl_debug_witness_watch(SYSCTL_HANDLER_ARGS) 2581 { 2582 int error, value; 2583 2584 value = witness_watch; 2585 error = sysctl_handle_int(oidp, &value, 0, req); 2586 if (error != 0 || req->newptr == NULL) 2587 return (error); 2588 if (value > 1 || value < -1 || 2589 (witness_watch == -1 && value != witness_watch)) 2590 return (EINVAL); 2591 witness_watch = value; 2592 return (0); 2593 } 2594 2595 static void 2596 witness_add_fullgraph(struct sbuf *sb, struct witness *w) 2597 { 2598 int i; 2599 2600 if (w->w_displayed != 0 || (w->w_file == NULL && w->w_line == 0)) 2601 return; 2602 w->w_displayed = 1; 2603 2604 WITNESS_INDEX_ASSERT(w->w_index); 2605 for (i = 1; i <= w_max_used_index; i++) { 2606 if (w_rmatrix[w->w_index][i] & WITNESS_PARENT) { 2607 sbuf_printf(sb, "\"%s\",\"%s\"\n", w->w_name, 2608 w_data[i].w_name); 2609 witness_add_fullgraph(sb, &w_data[i]); 2610 } 2611 } 2612 } 2613 2614 /* 2615 * A simple hash function. Takes a key pointer and a key size. If size == 0, 2616 * interprets the key as a string and reads until the null 2617 * terminator. Otherwise, reads the first size bytes. Returns an unsigned 32-bit 2618 * hash value computed from the key. 2619 */ 2620 static uint32_t 2621 witness_hash_djb2(const uint8_t *key, uint32_t size) 2622 { 2623 unsigned int hash = 5381; 2624 int i; 2625 2626 /* hash = hash * 33 + key[i] */ 2627 if (size) 2628 for (i = 0; i < size; i++) 2629 hash = ((hash << 5) + hash) + (unsigned int)key[i]; 2630 else 2631 for (i = 0; key[i] != 0; i++) 2632 hash = ((hash << 5) + hash) + (unsigned int)key[i]; 2633 2634 return (hash); 2635 } 2636 2637 2638 /* 2639 * Initializes the two witness hash tables. Called exactly once from 2640 * witness_initialize(). 2641 */ 2642 static void 2643 witness_init_hash_tables(void) 2644 { 2645 int i; 2646 2647 MPASS(witness_cold); 2648 2649 /* Initialize the hash tables. */ 2650 for (i = 0; i < WITNESS_HASH_SIZE; i++) 2651 w_hash.wh_array[i] = NULL; 2652 2653 w_hash.wh_size = WITNESS_HASH_SIZE; 2654 w_hash.wh_count = 0; 2655 2656 /* Initialize the lock order data hash. */ 2657 w_lofree = NULL; 2658 for (i = 0; i < WITNESS_LO_DATA_COUNT; i++) { 2659 memset(&w_lodata[i], 0, sizeof(w_lodata[i])); 2660 w_lodata[i].wlod_next = w_lofree; 2661 w_lofree = &w_lodata[i]; 2662 } 2663 w_lohash.wloh_size = WITNESS_LO_HASH_SIZE; 2664 w_lohash.wloh_count = 0; 2665 for (i = 0; i < WITNESS_LO_HASH_SIZE; i++) 2666 w_lohash.wloh_array[i] = NULL; 2667 } 2668 2669 static struct witness * 2670 witness_hash_get(const char *key) 2671 { 2672 struct witness *w; 2673 uint32_t hash; 2674 2675 MPASS(key != NULL); 2676 if (witness_cold == 0) 2677 mtx_assert(&w_mtx, MA_OWNED); 2678 hash = witness_hash_djb2(key, 0) % w_hash.wh_size; 2679 w = w_hash.wh_array[hash]; 2680 while (w != NULL) { 2681 if (strcmp(w->w_name, key) == 0) 2682 goto out; 2683 w = w->w_hash_next; 2684 } 2685 2686 out: 2687 return (w); 2688 } 2689 2690 static void 2691 witness_hash_put(struct witness *w) 2692 { 2693 uint32_t hash; 2694 2695 MPASS(w != NULL); 2696 MPASS(w->w_name != NULL); 2697 if (witness_cold == 0) 2698 mtx_assert(&w_mtx, MA_OWNED); 2699 KASSERT(witness_hash_get(w->w_name) == NULL, 2700 ("%s: trying to add a hash entry that already exists!", __func__)); 2701 KASSERT(w->w_hash_next == NULL, 2702 ("%s: w->w_hash_next != NULL", __func__)); 2703 2704 hash = witness_hash_djb2(w->w_name, 0) % w_hash.wh_size; 2705 w->w_hash_next = w_hash.wh_array[hash]; 2706 w_hash.wh_array[hash] = w; 2707 w_hash.wh_count++; 2708 } 2709 2710 2711 static struct witness_lock_order_data * 2712 witness_lock_order_get(struct witness *parent, struct witness *child) 2713 { 2714 struct witness_lock_order_data *data = NULL; 2715 struct witness_lock_order_key key; 2716 unsigned int hash; 2717 2718 MPASS(parent != NULL && child != NULL); 2719 key.from = parent->w_index; 2720 key.to = child->w_index; 2721 WITNESS_INDEX_ASSERT(key.from); 2722 WITNESS_INDEX_ASSERT(key.to); 2723 if ((w_rmatrix[parent->w_index][child->w_index] 2724 & WITNESS_LOCK_ORDER_KNOWN) == 0) 2725 goto out; 2726 2727 hash = witness_hash_djb2((const char*)&key, 2728 sizeof(key)) % w_lohash.wloh_size; 2729 data = w_lohash.wloh_array[hash]; 2730 while (data != NULL) { 2731 if (witness_lock_order_key_equal(&data->wlod_key, &key)) 2732 break; 2733 data = data->wlod_next; 2734 } 2735 2736 out: 2737 return (data); 2738 } 2739 2740 /* 2741 * Verify that parent and child have a known relationship, are not the same, 2742 * and child is actually a child of parent. This is done without w_mtx 2743 * to avoid contention in the common case. 2744 */ 2745 static int 2746 witness_lock_order_check(struct witness *parent, struct witness *child) 2747 { 2748 2749 if (parent != child && 2750 w_rmatrix[parent->w_index][child->w_index] 2751 & WITNESS_LOCK_ORDER_KNOWN && 2752 isitmychild(parent, child)) 2753 return (1); 2754 2755 return (0); 2756 } 2757 2758 static int 2759 witness_lock_order_add(struct witness *parent, struct witness *child) 2760 { 2761 struct witness_lock_order_data *data = NULL; 2762 struct witness_lock_order_key key; 2763 unsigned int hash; 2764 2765 MPASS(parent != NULL && child != NULL); 2766 key.from = parent->w_index; 2767 key.to = child->w_index; 2768 WITNESS_INDEX_ASSERT(key.from); 2769 WITNESS_INDEX_ASSERT(key.to); 2770 if (w_rmatrix[parent->w_index][child->w_index] 2771 & WITNESS_LOCK_ORDER_KNOWN) 2772 return (1); 2773 2774 hash = witness_hash_djb2((const char*)&key, 2775 sizeof(key)) % w_lohash.wloh_size; 2776 w_rmatrix[parent->w_index][child->w_index] |= WITNESS_LOCK_ORDER_KNOWN; 2777 data = w_lofree; 2778 if (data == NULL) 2779 return (0); 2780 w_lofree = data->wlod_next; 2781 data->wlod_next = w_lohash.wloh_array[hash]; 2782 data->wlod_key = key; 2783 w_lohash.wloh_array[hash] = data; 2784 w_lohash.wloh_count++; 2785 stack_zero(&data->wlod_stack); 2786 stack_save(&data->wlod_stack); 2787 return (1); 2788 } 2789 2790 /* Call this whenver the structure of the witness graph changes. */ 2791 static void 2792 witness_increment_graph_generation(void) 2793 { 2794 2795 if (witness_cold == 0) 2796 mtx_assert(&w_mtx, MA_OWNED); 2797 w_generation++; 2798 } 2799 2800 #ifdef KDB 2801 static void 2802 _witness_debugger(int cond, const char *msg) 2803 { 2804 2805 if (witness_trace && cond) 2806 kdb_backtrace(); 2807 if (witness_kdb && cond) 2808 kdb_enter(KDB_WHY_WITNESS, msg); 2809 } 2810 #endif 2811