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/syslog.h> 110 #include <sys/systm.h> 111 112 #ifdef DDB 113 #include <ddb/ddb.h> 114 #endif 115 116 #include <machine/stdarg.h> 117 118 #if !defined(DDB) && !defined(STACK) 119 #error "DDB or STACK options are required for WITNESS" 120 #endif 121 122 /* Note that these traces do not work with KTR_ALQ. */ 123 #if 0 124 #define KTR_WITNESS KTR_SUBSYS 125 #else 126 #define KTR_WITNESS 0 127 #endif 128 129 #define LI_RECURSEMASK 0x0000ffff /* Recursion depth of lock instance. */ 130 #define LI_EXCLUSIVE 0x00010000 /* Exclusive lock instance. */ 131 #define LI_NORELEASE 0x00020000 /* Lock not allowed to be released. */ 132 133 /* Define this to check for blessed mutexes */ 134 #undef BLESSING 135 136 #ifndef WITNESS_COUNT 137 #define WITNESS_COUNT 1536 138 #endif 139 #define WITNESS_HASH_SIZE 251 /* Prime, gives load factor < 2 */ 140 #define WITNESS_PENDLIST (1024 + MAXCPU) 141 142 /* Allocate 256 KB of stack data space */ 143 #define WITNESS_LO_DATA_COUNT 2048 144 145 /* Prime, gives load factor of ~2 at full load */ 146 #define WITNESS_LO_HASH_SIZE 1021 147 148 /* 149 * XXX: This is somewhat bogus, as we assume here that at most 2048 threads 150 * will hold LOCK_NCHILDREN locks. We handle failure ok, and we should 151 * probably be safe for the most part, but it's still a SWAG. 152 */ 153 #define LOCK_NCHILDREN 5 154 #define LOCK_CHILDCOUNT 2048 155 156 #define MAX_W_NAME 64 157 158 #define FULLGRAPH_SBUF_SIZE 512 159 160 /* 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 static 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_equal(const struct witness_lock_order_key *a, 310 const struct witness_lock_order_key *b) 311 { 312 313 return (a->from == b->from && a->to == b->to); 314 } 315 316 static int _isitmyx(struct witness *w1, struct witness *w2, int rmask, 317 const char *fname); 318 static void adopt(struct witness *parent, struct witness *child); 319 #ifdef BLESSING 320 static int blessed(struct witness *, struct witness *); 321 #endif 322 static void depart(struct witness *w); 323 static struct witness *enroll(const char *description, 324 struct lock_class *lock_class); 325 static struct lock_instance *find_instance(struct lock_list_entry *list, 326 const struct lock_object *lock); 327 static int isitmychild(struct witness *parent, struct witness *child); 328 static int isitmydescendant(struct witness *parent, struct witness *child); 329 static void itismychild(struct witness *parent, struct witness *child); 330 static int sysctl_debug_witness_badstacks(SYSCTL_HANDLER_ARGS); 331 static int sysctl_debug_witness_watch(SYSCTL_HANDLER_ARGS); 332 static int sysctl_debug_witness_fullgraph(SYSCTL_HANDLER_ARGS); 333 static int sysctl_debug_witness_channel(SYSCTL_HANDLER_ARGS); 334 static void witness_add_fullgraph(struct sbuf *sb, struct witness *parent); 335 #ifdef DDB 336 static void witness_ddb_compute_levels(void); 337 static void witness_ddb_display(int(*)(const char *fmt, ...)); 338 static void witness_ddb_display_descendants(int(*)(const char *fmt, ...), 339 struct witness *, int indent); 340 static void witness_ddb_display_list(int(*prnt)(const char *fmt, ...), 341 struct witness_list *list); 342 static void witness_ddb_level_descendants(struct witness *parent, int l); 343 static void witness_ddb_list(struct thread *td); 344 #endif 345 static void witness_debugger(int cond, const char *msg); 346 static void witness_free(struct witness *m); 347 static struct witness *witness_get(void); 348 static uint32_t witness_hash_djb2(const uint8_t *key, uint32_t size); 349 static struct witness *witness_hash_get(const char *key); 350 static void witness_hash_put(struct witness *w); 351 static void witness_init_hash_tables(void); 352 static void witness_increment_graph_generation(void); 353 static void witness_lock_list_free(struct lock_list_entry *lle); 354 static struct lock_list_entry *witness_lock_list_get(void); 355 static int witness_lock_order_add(struct witness *parent, 356 struct witness *child); 357 static int witness_lock_order_check(struct witness *parent, 358 struct witness *child); 359 static struct witness_lock_order_data *witness_lock_order_get( 360 struct witness *parent, 361 struct witness *child); 362 static void witness_list_lock(struct lock_instance *instance, 363 int (*prnt)(const char *fmt, ...)); 364 static int witness_output(const char *fmt, ...) __printflike(1, 2); 365 static int witness_voutput(const char *fmt, va_list ap) __printflike(1, 0); 366 static void witness_setflag(struct lock_object *lock, int flag, int set); 367 368 static SYSCTL_NODE(_debug, OID_AUTO, witness, CTLFLAG_RW, NULL, 369 "Witness Locking"); 370 371 /* 372 * If set to 0, lock order checking is disabled. If set to -1, 373 * witness is completely disabled. Otherwise witness performs full 374 * lock order checking for all locks. At runtime, lock order checking 375 * may be toggled. However, witness cannot be reenabled once it is 376 * completely disabled. 377 */ 378 static int witness_watch = 1; 379 SYSCTL_PROC(_debug_witness, OID_AUTO, watch, CTLFLAG_RWTUN | CTLTYPE_INT, NULL, 0, 380 sysctl_debug_witness_watch, "I", "witness is watching lock operations"); 381 382 #ifdef KDB 383 /* 384 * When KDB is enabled and witness_kdb is 1, it will cause the system 385 * to drop into kdebug() when: 386 * - a lock hierarchy violation occurs 387 * - locks are held when going to sleep. 388 */ 389 #ifdef WITNESS_KDB 390 int witness_kdb = 1; 391 #else 392 int witness_kdb = 0; 393 #endif 394 SYSCTL_INT(_debug_witness, OID_AUTO, kdb, CTLFLAG_RWTUN, &witness_kdb, 0, ""); 395 #endif /* KDB */ 396 397 #if defined(DDB) || defined(KDB) 398 /* 399 * When DDB or KDB is enabled and witness_trace is 1, it will cause the system 400 * to print a stack trace: 401 * - a lock hierarchy violation occurs 402 * - locks are held when going to sleep. 403 */ 404 int witness_trace = 1; 405 SYSCTL_INT(_debug_witness, OID_AUTO, trace, CTLFLAG_RWTUN, &witness_trace, 0, ""); 406 #endif /* DDB || KDB */ 407 408 #ifdef WITNESS_SKIPSPIN 409 int witness_skipspin = 1; 410 #else 411 int witness_skipspin = 0; 412 #endif 413 SYSCTL_INT(_debug_witness, OID_AUTO, skipspin, CTLFLAG_RDTUN, &witness_skipspin, 0, ""); 414 415 int badstack_sbuf_size; 416 417 int witness_count = WITNESS_COUNT; 418 SYSCTL_INT(_debug_witness, OID_AUTO, witness_count, CTLFLAG_RDTUN, 419 &witness_count, 0, ""); 420 421 /* 422 * Output channel for witness messages. By default we print to the console. 423 */ 424 enum witness_channel { 425 WITNESS_CONSOLE, 426 WITNESS_LOG, 427 WITNESS_NONE, 428 }; 429 430 static enum witness_channel witness_channel = WITNESS_CONSOLE; 431 SYSCTL_PROC(_debug_witness, OID_AUTO, output_channel, CTLTYPE_STRING | 432 CTLFLAG_RWTUN, NULL, 0, sysctl_debug_witness_channel, "A", 433 "Output channel for warnings"); 434 435 /* 436 * Call this to print out the relations between locks. 437 */ 438 SYSCTL_PROC(_debug_witness, OID_AUTO, fullgraph, CTLTYPE_STRING | CTLFLAG_RD, 439 NULL, 0, sysctl_debug_witness_fullgraph, "A", "Show locks relation graphs"); 440 441 /* 442 * Call this to print out the witness faulty stacks. 443 */ 444 SYSCTL_PROC(_debug_witness, OID_AUTO, badstacks, CTLTYPE_STRING | CTLFLAG_RD, 445 NULL, 0, sysctl_debug_witness_badstacks, "A", "Show bad witness stacks"); 446 447 static struct mtx w_mtx; 448 449 /* w_list */ 450 static struct witness_list w_free = STAILQ_HEAD_INITIALIZER(w_free); 451 static struct witness_list w_all = STAILQ_HEAD_INITIALIZER(w_all); 452 453 /* w_typelist */ 454 static struct witness_list w_spin = STAILQ_HEAD_INITIALIZER(w_spin); 455 static struct witness_list w_sleep = STAILQ_HEAD_INITIALIZER(w_sleep); 456 457 /* lock list */ 458 static struct lock_list_entry *w_lock_list_free = NULL; 459 static struct witness_pendhelp pending_locks[WITNESS_PENDLIST]; 460 static u_int pending_cnt; 461 462 static int w_free_cnt, w_spin_cnt, w_sleep_cnt; 463 SYSCTL_INT(_debug_witness, OID_AUTO, free_cnt, CTLFLAG_RD, &w_free_cnt, 0, ""); 464 SYSCTL_INT(_debug_witness, OID_AUTO, spin_cnt, CTLFLAG_RD, &w_spin_cnt, 0, ""); 465 SYSCTL_INT(_debug_witness, OID_AUTO, sleep_cnt, CTLFLAG_RD, &w_sleep_cnt, 0, 466 ""); 467 468 static struct witness *w_data; 469 static uint8_t **w_rmatrix; 470 static struct lock_list_entry w_locklistdata[LOCK_CHILDCOUNT]; 471 static struct witness_hash w_hash; /* The witness hash table. */ 472 473 /* The lock order data hash */ 474 static struct witness_lock_order_data w_lodata[WITNESS_LO_DATA_COUNT]; 475 static struct witness_lock_order_data *w_lofree = NULL; 476 static struct witness_lock_order_hash w_lohash; 477 static int w_max_used_index = 0; 478 static unsigned int w_generation = 0; 479 static const char w_notrunning[] = "Witness not running\n"; 480 static const char w_stillcold[] = "Witness is still cold\n"; 481 482 483 static struct witness_order_list_entry order_lists[] = { 484 /* 485 * sx locks 486 */ 487 { "proctree", &lock_class_sx }, 488 { "allproc", &lock_class_sx }, 489 { "allprison", &lock_class_sx }, 490 { NULL, NULL }, 491 /* 492 * Various mutexes 493 */ 494 { "Giant", &lock_class_mtx_sleep }, 495 { "pipe mutex", &lock_class_mtx_sleep }, 496 { "sigio lock", &lock_class_mtx_sleep }, 497 { "process group", &lock_class_mtx_sleep }, 498 { "process lock", &lock_class_mtx_sleep }, 499 { "session", &lock_class_mtx_sleep }, 500 { "uidinfo hash", &lock_class_rw }, 501 #ifdef HWPMC_HOOKS 502 { "pmc-sleep", &lock_class_mtx_sleep }, 503 #endif 504 { "time lock", &lock_class_mtx_sleep }, 505 { NULL, NULL }, 506 /* 507 * umtx 508 */ 509 { "umtx lock", &lock_class_mtx_sleep }, 510 { NULL, NULL }, 511 /* 512 * Sockets 513 */ 514 { "accept", &lock_class_mtx_sleep }, 515 { "so_snd", &lock_class_mtx_sleep }, 516 { "so_rcv", &lock_class_mtx_sleep }, 517 { "sellck", &lock_class_mtx_sleep }, 518 { NULL, NULL }, 519 /* 520 * Routing 521 */ 522 { "so_rcv", &lock_class_mtx_sleep }, 523 { "radix node head", &lock_class_rw }, 524 { "rtentry", &lock_class_mtx_sleep }, 525 { "ifaddr", &lock_class_mtx_sleep }, 526 { NULL, NULL }, 527 /* 528 * IPv4 multicast: 529 * protocol locks before interface locks, after UDP locks. 530 */ 531 { "udpinp", &lock_class_rw }, 532 { "in_multi_mtx", &lock_class_mtx_sleep }, 533 { "igmp_mtx", &lock_class_mtx_sleep }, 534 { "if_addr_lock", &lock_class_rw }, 535 { NULL, NULL }, 536 /* 537 * IPv6 multicast: 538 * protocol locks before interface locks, after UDP locks. 539 */ 540 { "udpinp", &lock_class_rw }, 541 { "in6_multi_mtx", &lock_class_mtx_sleep }, 542 { "mld_mtx", &lock_class_mtx_sleep }, 543 { "if_addr_lock", &lock_class_rw }, 544 { NULL, NULL }, 545 /* 546 * UNIX Domain Sockets 547 */ 548 { "unp_link_rwlock", &lock_class_rw }, 549 { "unp_list_lock", &lock_class_mtx_sleep }, 550 { "unp", &lock_class_mtx_sleep }, 551 { "so_snd", &lock_class_mtx_sleep }, 552 { NULL, NULL }, 553 /* 554 * UDP/IP 555 */ 556 { "udp", &lock_class_rw }, 557 { "udpinp", &lock_class_rw }, 558 { "so_snd", &lock_class_mtx_sleep }, 559 { NULL, NULL }, 560 /* 561 * TCP/IP 562 */ 563 { "tcp", &lock_class_rw }, 564 { "tcpinp", &lock_class_rw }, 565 { "so_snd", &lock_class_mtx_sleep }, 566 { NULL, NULL }, 567 /* 568 * BPF 569 */ 570 { "bpf global lock", &lock_class_mtx_sleep }, 571 { "bpf interface lock", &lock_class_rw }, 572 { "bpf cdev lock", &lock_class_mtx_sleep }, 573 { NULL, NULL }, 574 /* 575 * NFS server 576 */ 577 { "nfsd_mtx", &lock_class_mtx_sleep }, 578 { "so_snd", &lock_class_mtx_sleep }, 579 { NULL, NULL }, 580 581 /* 582 * IEEE 802.11 583 */ 584 { "802.11 com lock", &lock_class_mtx_sleep}, 585 { NULL, NULL }, 586 /* 587 * Network drivers 588 */ 589 { "network driver", &lock_class_mtx_sleep}, 590 { NULL, NULL }, 591 592 /* 593 * Netgraph 594 */ 595 { "ng_node", &lock_class_mtx_sleep }, 596 { "ng_worklist", &lock_class_mtx_sleep }, 597 { NULL, NULL }, 598 /* 599 * CDEV 600 */ 601 { "vm map (system)", &lock_class_mtx_sleep }, 602 { "vm page queue", &lock_class_mtx_sleep }, 603 { "vnode interlock", &lock_class_mtx_sleep }, 604 { "cdev", &lock_class_mtx_sleep }, 605 { NULL, NULL }, 606 /* 607 * VM 608 */ 609 { "vm map (user)", &lock_class_sx }, 610 { "vm object", &lock_class_rw }, 611 { "vm page", &lock_class_mtx_sleep }, 612 { "vm page queue", &lock_class_mtx_sleep }, 613 { "pmap pv global", &lock_class_rw }, 614 { "pmap", &lock_class_mtx_sleep }, 615 { "pmap pv list", &lock_class_rw }, 616 { "vm page free queue", &lock_class_mtx_sleep }, 617 { NULL, NULL }, 618 /* 619 * kqueue/VFS interaction 620 */ 621 { "kqueue", &lock_class_mtx_sleep }, 622 { "struct mount mtx", &lock_class_mtx_sleep }, 623 { "vnode interlock", &lock_class_mtx_sleep }, 624 { NULL, NULL }, 625 /* 626 * ZFS locking 627 */ 628 { "dn->dn_mtx", &lock_class_sx }, 629 { "dr->dt.di.dr_mtx", &lock_class_sx }, 630 { "db->db_mtx", &lock_class_sx }, 631 { NULL, NULL }, 632 /* 633 * spin locks 634 */ 635 #ifdef SMP 636 { "ap boot", &lock_class_mtx_spin }, 637 #endif 638 { "rm.mutex_mtx", &lock_class_mtx_spin }, 639 { "sio", &lock_class_mtx_spin }, 640 #ifdef __i386__ 641 { "cy", &lock_class_mtx_spin }, 642 #endif 643 #ifdef __sparc64__ 644 { "pcib_mtx", &lock_class_mtx_spin }, 645 { "rtc_mtx", &lock_class_mtx_spin }, 646 #endif 647 { "scc_hwmtx", &lock_class_mtx_spin }, 648 { "uart_hwmtx", &lock_class_mtx_spin }, 649 { "fast_taskqueue", &lock_class_mtx_spin }, 650 { "intr table", &lock_class_mtx_spin }, 651 #ifdef HWPMC_HOOKS 652 { "pmc-per-proc", &lock_class_mtx_spin }, 653 #endif 654 { "process slock", &lock_class_mtx_spin }, 655 { "syscons video lock", &lock_class_mtx_spin }, 656 { "sleepq chain", &lock_class_mtx_spin }, 657 { "rm_spinlock", &lock_class_mtx_spin }, 658 { "turnstile chain", &lock_class_mtx_spin }, 659 { "turnstile lock", &lock_class_mtx_spin }, 660 { "sched lock", &lock_class_mtx_spin }, 661 { "td_contested", &lock_class_mtx_spin }, 662 { "callout", &lock_class_mtx_spin }, 663 { "entropy harvest mutex", &lock_class_mtx_spin }, 664 #ifdef SMP 665 { "smp rendezvous", &lock_class_mtx_spin }, 666 #endif 667 #ifdef __powerpc__ 668 { "tlb0", &lock_class_mtx_spin }, 669 #endif 670 /* 671 * leaf locks 672 */ 673 { "intrcnt", &lock_class_mtx_spin }, 674 { "icu", &lock_class_mtx_spin }, 675 #if defined(SMP) && defined(__sparc64__) 676 { "ipi", &lock_class_mtx_spin }, 677 #endif 678 #ifdef __i386__ 679 { "allpmaps", &lock_class_mtx_spin }, 680 { "descriptor tables", &lock_class_mtx_spin }, 681 #endif 682 { "clk", &lock_class_mtx_spin }, 683 { "cpuset", &lock_class_mtx_spin }, 684 { "mprof lock", &lock_class_mtx_spin }, 685 { "zombie lock", &lock_class_mtx_spin }, 686 { "ALD Queue", &lock_class_mtx_spin }, 687 #if defined(__i386__) || defined(__amd64__) 688 { "pcicfg", &lock_class_mtx_spin }, 689 { "NDIS thread lock", &lock_class_mtx_spin }, 690 #endif 691 { "tw_osl_io_lock", &lock_class_mtx_spin }, 692 { "tw_osl_q_lock", &lock_class_mtx_spin }, 693 { "tw_cl_io_lock", &lock_class_mtx_spin }, 694 { "tw_cl_intr_lock", &lock_class_mtx_spin }, 695 { "tw_cl_gen_lock", &lock_class_mtx_spin }, 696 #ifdef HWPMC_HOOKS 697 { "pmc-leaf", &lock_class_mtx_spin }, 698 #endif 699 { "blocked lock", &lock_class_mtx_spin }, 700 { NULL, NULL }, 701 { NULL, NULL } 702 }; 703 704 #ifdef BLESSING 705 /* 706 * Pairs of locks which have been blessed 707 * Don't complain about order problems with blessed locks 708 */ 709 static struct witness_blessed blessed_list[] = { 710 }; 711 #endif 712 713 /* 714 * This global is set to 0 once it becomes safe to use the witness code. 715 */ 716 static int witness_cold = 1; 717 718 /* 719 * This global is set to 1 once the static lock orders have been enrolled 720 * so that a warning can be issued for any spin locks enrolled later. 721 */ 722 static int witness_spin_warn = 0; 723 724 /* Trim useless garbage from filenames. */ 725 static const char * 726 fixup_filename(const char *file) 727 { 728 729 if (file == NULL) 730 return (NULL); 731 while (strncmp(file, "../", 3) == 0) 732 file += 3; 733 return (file); 734 } 735 736 /* 737 * The WITNESS-enabled diagnostic code. Note that the witness code does 738 * assume that the early boot is single-threaded at least until after this 739 * routine is completed. 740 */ 741 static void 742 witness_initialize(void *dummy __unused) 743 { 744 struct lock_object *lock; 745 struct witness_order_list_entry *order; 746 struct witness *w, *w1; 747 int i; 748 749 w_data = malloc(sizeof (struct witness) * witness_count, M_WITNESS, 750 M_WAITOK | M_ZERO); 751 752 w_rmatrix = malloc(sizeof(*w_rmatrix) * (witness_count + 1), 753 M_WITNESS, M_WAITOK | M_ZERO); 754 755 for (i = 0; i < witness_count + 1; i++) { 756 w_rmatrix[i] = malloc(sizeof(*w_rmatrix[i]) * 757 (witness_count + 1), M_WITNESS, M_WAITOK | M_ZERO); 758 } 759 badstack_sbuf_size = witness_count * 256; 760 761 /* 762 * We have to release Giant before initializing its witness 763 * structure so that WITNESS doesn't get confused. 764 */ 765 mtx_unlock(&Giant); 766 mtx_assert(&Giant, MA_NOTOWNED); 767 768 CTR1(KTR_WITNESS, "%s: initializing witness", __func__); 769 mtx_init(&w_mtx, "witness lock", NULL, MTX_SPIN | MTX_QUIET | 770 MTX_NOWITNESS | MTX_NOPROFILE); 771 for (i = witness_count - 1; i >= 0; i--) { 772 w = &w_data[i]; 773 memset(w, 0, sizeof(*w)); 774 w_data[i].w_index = i; /* Witness index never changes. */ 775 witness_free(w); 776 } 777 KASSERT(STAILQ_FIRST(&w_free)->w_index == 0, 778 ("%s: Invalid list of free witness objects", __func__)); 779 780 /* Witness with index 0 is not used to aid in debugging. */ 781 STAILQ_REMOVE_HEAD(&w_free, w_list); 782 w_free_cnt--; 783 784 for (i = 0; i < witness_count; i++) { 785 memset(w_rmatrix[i], 0, sizeof(*w_rmatrix[i]) * 786 (witness_count + 1)); 787 } 788 789 for (i = 0; i < LOCK_CHILDCOUNT; i++) 790 witness_lock_list_free(&w_locklistdata[i]); 791 witness_init_hash_tables(); 792 793 /* First add in all the specified order lists. */ 794 for (order = order_lists; order->w_name != NULL; order++) { 795 w = enroll(order->w_name, order->w_class); 796 if (w == NULL) 797 continue; 798 w->w_file = "order list"; 799 for (order++; order->w_name != NULL; order++) { 800 w1 = enroll(order->w_name, order->w_class); 801 if (w1 == NULL) 802 continue; 803 w1->w_file = "order list"; 804 itismychild(w, w1); 805 w = w1; 806 } 807 } 808 witness_spin_warn = 1; 809 810 /* Iterate through all locks and add them to witness. */ 811 for (i = 0; pending_locks[i].wh_lock != NULL; i++) { 812 lock = pending_locks[i].wh_lock; 813 KASSERT(lock->lo_flags & LO_WITNESS, 814 ("%s: lock %s is on pending list but not LO_WITNESS", 815 __func__, lock->lo_name)); 816 lock->lo_witness = enroll(pending_locks[i].wh_type, 817 LOCK_CLASS(lock)); 818 } 819 820 /* Mark the witness code as being ready for use. */ 821 witness_cold = 0; 822 823 mtx_lock(&Giant); 824 } 825 SYSINIT(witness_init, SI_SUB_WITNESS, SI_ORDER_FIRST, witness_initialize, 826 NULL); 827 828 void 829 witness_init(struct lock_object *lock, const char *type) 830 { 831 struct lock_class *class; 832 833 /* Various sanity checks. */ 834 class = LOCK_CLASS(lock); 835 if ((lock->lo_flags & LO_RECURSABLE) != 0 && 836 (class->lc_flags & LC_RECURSABLE) == 0) 837 kassert_panic("%s: lock (%s) %s can not be recursable", 838 __func__, class->lc_name, lock->lo_name); 839 if ((lock->lo_flags & LO_SLEEPABLE) != 0 && 840 (class->lc_flags & LC_SLEEPABLE) == 0) 841 kassert_panic("%s: lock (%s) %s can not be sleepable", 842 __func__, class->lc_name, lock->lo_name); 843 if ((lock->lo_flags & LO_UPGRADABLE) != 0 && 844 (class->lc_flags & LC_UPGRADABLE) == 0) 845 kassert_panic("%s: lock (%s) %s can not be upgradable", 846 __func__, class->lc_name, lock->lo_name); 847 848 /* 849 * If we shouldn't watch this lock, then just clear lo_witness. 850 * Otherwise, if witness_cold is set, then it is too early to 851 * enroll this lock, so defer it to witness_initialize() by adding 852 * it to the pending_locks list. If it is not too early, then enroll 853 * the lock now. 854 */ 855 if (witness_watch < 1 || panicstr != NULL || 856 (lock->lo_flags & LO_WITNESS) == 0) 857 lock->lo_witness = NULL; 858 else if (witness_cold) { 859 pending_locks[pending_cnt].wh_lock = lock; 860 pending_locks[pending_cnt++].wh_type = type; 861 if (pending_cnt > WITNESS_PENDLIST) 862 panic("%s: pending locks list is too small, " 863 "increase WITNESS_PENDLIST\n", 864 __func__); 865 } else 866 lock->lo_witness = enroll(type, class); 867 } 868 869 void 870 witness_destroy(struct lock_object *lock) 871 { 872 struct lock_class *class; 873 struct witness *w; 874 875 class = LOCK_CLASS(lock); 876 877 if (witness_cold) 878 panic("lock (%s) %s destroyed while witness_cold", 879 class->lc_name, lock->lo_name); 880 881 /* XXX: need to verify that no one holds the lock */ 882 if ((lock->lo_flags & LO_WITNESS) == 0 || lock->lo_witness == NULL) 883 return; 884 w = lock->lo_witness; 885 886 mtx_lock_spin(&w_mtx); 887 MPASS(w->w_refcount > 0); 888 w->w_refcount--; 889 890 if (w->w_refcount == 0) 891 depart(w); 892 mtx_unlock_spin(&w_mtx); 893 } 894 895 #ifdef DDB 896 static void 897 witness_ddb_compute_levels(void) 898 { 899 struct witness *w; 900 901 /* 902 * First clear all levels. 903 */ 904 STAILQ_FOREACH(w, &w_all, w_list) 905 w->w_ddb_level = -1; 906 907 /* 908 * Look for locks with no parents and level all their descendants. 909 */ 910 STAILQ_FOREACH(w, &w_all, w_list) { 911 912 /* If the witness has ancestors (is not a root), skip it. */ 913 if (w->w_num_ancestors > 0) 914 continue; 915 witness_ddb_level_descendants(w, 0); 916 } 917 } 918 919 static void 920 witness_ddb_level_descendants(struct witness *w, int l) 921 { 922 int i; 923 924 if (w->w_ddb_level >= l) 925 return; 926 927 w->w_ddb_level = l; 928 l++; 929 930 for (i = 1; i <= w_max_used_index; i++) { 931 if (w_rmatrix[w->w_index][i] & WITNESS_PARENT) 932 witness_ddb_level_descendants(&w_data[i], l); 933 } 934 } 935 936 static void 937 witness_ddb_display_descendants(int(*prnt)(const char *fmt, ...), 938 struct witness *w, int indent) 939 { 940 int i; 941 942 for (i = 0; i < indent; i++) 943 prnt(" "); 944 prnt("%s (type: %s, depth: %d, active refs: %d)", 945 w->w_name, w->w_class->lc_name, 946 w->w_ddb_level, w->w_refcount); 947 if (w->w_displayed) { 948 prnt(" -- (already displayed)\n"); 949 return; 950 } 951 w->w_displayed = 1; 952 if (w->w_file != NULL && w->w_line != 0) 953 prnt(" -- last acquired @ %s:%d\n", fixup_filename(w->w_file), 954 w->w_line); 955 else 956 prnt(" -- never acquired\n"); 957 indent++; 958 WITNESS_INDEX_ASSERT(w->w_index); 959 for (i = 1; i <= w_max_used_index; i++) { 960 if (db_pager_quit) 961 return; 962 if (w_rmatrix[w->w_index][i] & WITNESS_PARENT) 963 witness_ddb_display_descendants(prnt, &w_data[i], 964 indent); 965 } 966 } 967 968 static void 969 witness_ddb_display_list(int(*prnt)(const char *fmt, ...), 970 struct witness_list *list) 971 { 972 struct witness *w; 973 974 STAILQ_FOREACH(w, list, w_typelist) { 975 if (w->w_file == NULL || w->w_ddb_level > 0) 976 continue; 977 978 /* This lock has no anscestors - display its descendants. */ 979 witness_ddb_display_descendants(prnt, w, 0); 980 if (db_pager_quit) 981 return; 982 } 983 } 984 985 static void 986 witness_ddb_display(int(*prnt)(const char *fmt, ...)) 987 { 988 struct witness *w; 989 990 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); 991 witness_ddb_compute_levels(); 992 993 /* Clear all the displayed flags. */ 994 STAILQ_FOREACH(w, &w_all, w_list) 995 w->w_displayed = 0; 996 997 /* 998 * First, handle sleep locks which have been acquired at least 999 * once. 1000 */ 1001 prnt("Sleep locks:\n"); 1002 witness_ddb_display_list(prnt, &w_sleep); 1003 if (db_pager_quit) 1004 return; 1005 1006 /* 1007 * Now do spin locks which have been acquired at least once. 1008 */ 1009 prnt("\nSpin locks:\n"); 1010 witness_ddb_display_list(prnt, &w_spin); 1011 if (db_pager_quit) 1012 return; 1013 1014 /* 1015 * Finally, any locks which have not been acquired yet. 1016 */ 1017 prnt("\nLocks which were never acquired:\n"); 1018 STAILQ_FOREACH(w, &w_all, w_list) { 1019 if (w->w_file != NULL || w->w_refcount == 0) 1020 continue; 1021 prnt("%s (type: %s, depth: %d)\n", w->w_name, 1022 w->w_class->lc_name, w->w_ddb_level); 1023 if (db_pager_quit) 1024 return; 1025 } 1026 } 1027 #endif /* DDB */ 1028 1029 int 1030 witness_defineorder(struct lock_object *lock1, struct lock_object *lock2) 1031 { 1032 1033 if (witness_watch == -1 || panicstr != NULL) 1034 return (0); 1035 1036 /* Require locks that witness knows about. */ 1037 if (lock1 == NULL || lock1->lo_witness == NULL || lock2 == NULL || 1038 lock2->lo_witness == NULL) 1039 return (EINVAL); 1040 1041 mtx_assert(&w_mtx, MA_NOTOWNED); 1042 mtx_lock_spin(&w_mtx); 1043 1044 /* 1045 * If we already have either an explicit or implied lock order that 1046 * is the other way around, then return an error. 1047 */ 1048 if (witness_watch && 1049 isitmydescendant(lock2->lo_witness, lock1->lo_witness)) { 1050 mtx_unlock_spin(&w_mtx); 1051 return (EDOOFUS); 1052 } 1053 1054 /* Try to add the new order. */ 1055 CTR3(KTR_WITNESS, "%s: adding %s as a child of %s", __func__, 1056 lock2->lo_witness->w_name, lock1->lo_witness->w_name); 1057 itismychild(lock1->lo_witness, lock2->lo_witness); 1058 mtx_unlock_spin(&w_mtx); 1059 return (0); 1060 } 1061 1062 void 1063 witness_checkorder(struct lock_object *lock, int flags, const char *file, 1064 int line, struct lock_object *interlock) 1065 { 1066 struct lock_list_entry *lock_list, *lle; 1067 struct lock_instance *lock1, *lock2, *plock; 1068 struct lock_class *class, *iclass; 1069 struct witness *w, *w1; 1070 struct thread *td; 1071 int i, j; 1072 1073 if (witness_cold || witness_watch < 1 || lock->lo_witness == NULL || 1074 panicstr != NULL) 1075 return; 1076 1077 w = lock->lo_witness; 1078 class = LOCK_CLASS(lock); 1079 td = curthread; 1080 1081 if (class->lc_flags & LC_SLEEPLOCK) { 1082 1083 /* 1084 * Since spin locks include a critical section, this check 1085 * implicitly enforces a lock order of all sleep locks before 1086 * all spin locks. 1087 */ 1088 if (td->td_critnest != 0 && !kdb_active) 1089 kassert_panic("acquiring blockable sleep lock with " 1090 "spinlock or critical section held (%s) %s @ %s:%d", 1091 class->lc_name, lock->lo_name, 1092 fixup_filename(file), line); 1093 1094 /* 1095 * If this is the first lock acquired then just return as 1096 * no order checking is needed. 1097 */ 1098 lock_list = td->td_sleeplocks; 1099 if (lock_list == NULL || lock_list->ll_count == 0) 1100 return; 1101 } else { 1102 1103 /* 1104 * If this is the first lock, just return as no order 1105 * checking is needed. Avoid problems with thread 1106 * migration pinning the thread while checking if 1107 * spinlocks are held. If at least one spinlock is held 1108 * the thread is in a safe path and it is allowed to 1109 * unpin it. 1110 */ 1111 sched_pin(); 1112 lock_list = PCPU_GET(spinlocks); 1113 if (lock_list == NULL || lock_list->ll_count == 0) { 1114 sched_unpin(); 1115 return; 1116 } 1117 sched_unpin(); 1118 } 1119 1120 /* 1121 * Check to see if we are recursing on a lock we already own. If 1122 * so, make sure that we don't mismatch exclusive and shared lock 1123 * acquires. 1124 */ 1125 lock1 = find_instance(lock_list, lock); 1126 if (lock1 != NULL) { 1127 if ((lock1->li_flags & LI_EXCLUSIVE) != 0 && 1128 (flags & LOP_EXCLUSIVE) == 0) { 1129 witness_output("shared lock of (%s) %s @ %s:%d\n", 1130 class->lc_name, lock->lo_name, 1131 fixup_filename(file), line); 1132 witness_output("while exclusively locked from %s:%d\n", 1133 fixup_filename(lock1->li_file), lock1->li_line); 1134 kassert_panic("excl->share"); 1135 } 1136 if ((lock1->li_flags & LI_EXCLUSIVE) == 0 && 1137 (flags & LOP_EXCLUSIVE) != 0) { 1138 witness_output("exclusive lock of (%s) %s @ %s:%d\n", 1139 class->lc_name, lock->lo_name, 1140 fixup_filename(file), line); 1141 witness_output("while share locked from %s:%d\n", 1142 fixup_filename(lock1->li_file), lock1->li_line); 1143 kassert_panic("share->excl"); 1144 } 1145 return; 1146 } 1147 1148 /* Warn if the interlock is not locked exactly once. */ 1149 if (interlock != NULL) { 1150 iclass = LOCK_CLASS(interlock); 1151 lock1 = find_instance(lock_list, interlock); 1152 if (lock1 == NULL) 1153 kassert_panic("interlock (%s) %s not locked @ %s:%d", 1154 iclass->lc_name, interlock->lo_name, 1155 fixup_filename(file), line); 1156 else if ((lock1->li_flags & LI_RECURSEMASK) != 0) 1157 kassert_panic("interlock (%s) %s recursed @ %s:%d", 1158 iclass->lc_name, interlock->lo_name, 1159 fixup_filename(file), line); 1160 } 1161 1162 /* 1163 * Find the previously acquired lock, but ignore interlocks. 1164 */ 1165 plock = &lock_list->ll_children[lock_list->ll_count - 1]; 1166 if (interlock != NULL && plock->li_lock == interlock) { 1167 if (lock_list->ll_count > 1) 1168 plock = 1169 &lock_list->ll_children[lock_list->ll_count - 2]; 1170 else { 1171 lle = lock_list->ll_next; 1172 1173 /* 1174 * The interlock is the only lock we hold, so 1175 * simply return. 1176 */ 1177 if (lle == NULL) 1178 return; 1179 plock = &lle->ll_children[lle->ll_count - 1]; 1180 } 1181 } 1182 1183 /* 1184 * Try to perform most checks without a lock. If this succeeds we 1185 * can skip acquiring the lock and return success. Otherwise we redo 1186 * the check with the lock held to handle races with concurrent updates. 1187 */ 1188 w1 = plock->li_lock->lo_witness; 1189 if (witness_lock_order_check(w1, w)) 1190 return; 1191 1192 mtx_lock_spin(&w_mtx); 1193 if (witness_lock_order_check(w1, w)) { 1194 mtx_unlock_spin(&w_mtx); 1195 return; 1196 } 1197 witness_lock_order_add(w1, w); 1198 1199 /* 1200 * Check for duplicate locks of the same type. Note that we only 1201 * have to check for this on the last lock we just acquired. Any 1202 * other cases will be caught as lock order violations. 1203 */ 1204 if (w1 == w) { 1205 i = w->w_index; 1206 if (!(lock->lo_flags & LO_DUPOK) && !(flags & LOP_DUPOK) && 1207 !(w_rmatrix[i][i] & WITNESS_REVERSAL)) { 1208 w_rmatrix[i][i] |= WITNESS_REVERSAL; 1209 w->w_reversed = 1; 1210 mtx_unlock_spin(&w_mtx); 1211 witness_output( 1212 "acquiring duplicate lock of same type: \"%s\"\n", 1213 w->w_name); 1214 witness_output(" 1st %s @ %s:%d\n", plock->li_lock->lo_name, 1215 fixup_filename(plock->li_file), plock->li_line); 1216 witness_output(" 2nd %s @ %s:%d\n", lock->lo_name, 1217 fixup_filename(file), line); 1218 witness_debugger(1, __func__); 1219 } else 1220 mtx_unlock_spin(&w_mtx); 1221 return; 1222 } 1223 mtx_assert(&w_mtx, MA_OWNED); 1224 1225 /* 1226 * If we know that the lock we are acquiring comes after 1227 * the lock we most recently acquired in the lock order tree, 1228 * then there is no need for any further checks. 1229 */ 1230 if (isitmychild(w1, w)) 1231 goto out; 1232 1233 for (j = 0, lle = lock_list; lle != NULL; lle = lle->ll_next) { 1234 for (i = lle->ll_count - 1; i >= 0; i--, j++) { 1235 1236 MPASS(j < LOCK_CHILDCOUNT * LOCK_NCHILDREN); 1237 lock1 = &lle->ll_children[i]; 1238 1239 /* 1240 * Ignore the interlock. 1241 */ 1242 if (interlock == lock1->li_lock) 1243 continue; 1244 1245 /* 1246 * If this lock doesn't undergo witness checking, 1247 * then skip it. 1248 */ 1249 w1 = lock1->li_lock->lo_witness; 1250 if (w1 == NULL) { 1251 KASSERT((lock1->li_lock->lo_flags & LO_WITNESS) == 0, 1252 ("lock missing witness structure")); 1253 continue; 1254 } 1255 1256 /* 1257 * If we are locking Giant and this is a sleepable 1258 * lock, then skip it. 1259 */ 1260 if ((lock1->li_lock->lo_flags & LO_SLEEPABLE) != 0 && 1261 lock == &Giant.lock_object) 1262 continue; 1263 1264 /* 1265 * If we are locking a sleepable lock and this lock 1266 * is Giant, then skip it. 1267 */ 1268 if ((lock->lo_flags & LO_SLEEPABLE) != 0 && 1269 lock1->li_lock == &Giant.lock_object) 1270 continue; 1271 1272 /* 1273 * If we are locking a sleepable lock and this lock 1274 * isn't sleepable, we want to treat it as a lock 1275 * order violation to enfore a general lock order of 1276 * sleepable locks before non-sleepable locks. 1277 */ 1278 if (((lock->lo_flags & LO_SLEEPABLE) != 0 && 1279 (lock1->li_lock->lo_flags & LO_SLEEPABLE) == 0)) 1280 goto reversal; 1281 1282 /* 1283 * If we are locking Giant and this is a non-sleepable 1284 * lock, then treat it as a reversal. 1285 */ 1286 if ((lock1->li_lock->lo_flags & LO_SLEEPABLE) == 0 && 1287 lock == &Giant.lock_object) 1288 goto reversal; 1289 1290 /* 1291 * Check the lock order hierarchy for a reveresal. 1292 */ 1293 if (!isitmydescendant(w, w1)) 1294 continue; 1295 reversal: 1296 1297 /* 1298 * We have a lock order violation, check to see if it 1299 * is allowed or has already been yelled about. 1300 */ 1301 #ifdef BLESSING 1302 1303 /* 1304 * If the lock order is blessed, just bail. We don't 1305 * look for other lock order violations though, which 1306 * may be a bug. 1307 */ 1308 if (blessed(w, w1)) 1309 goto out; 1310 #endif 1311 1312 /* Bail if this violation is known */ 1313 if (w_rmatrix[w1->w_index][w->w_index] & WITNESS_REVERSAL) 1314 goto out; 1315 1316 /* Record this as a violation */ 1317 w_rmatrix[w1->w_index][w->w_index] |= WITNESS_REVERSAL; 1318 w_rmatrix[w->w_index][w1->w_index] |= WITNESS_REVERSAL; 1319 w->w_reversed = w1->w_reversed = 1; 1320 witness_increment_graph_generation(); 1321 mtx_unlock_spin(&w_mtx); 1322 1323 #ifdef WITNESS_NO_VNODE 1324 /* 1325 * There are known LORs between VNODE locks. They are 1326 * not an indication of a bug. VNODE locks are flagged 1327 * as such (LO_IS_VNODE) and we don't yell if the LOR 1328 * is between 2 VNODE locks. 1329 */ 1330 if ((lock->lo_flags & LO_IS_VNODE) != 0 && 1331 (lock1->li_lock->lo_flags & LO_IS_VNODE) != 0) 1332 return; 1333 #endif 1334 1335 /* 1336 * Ok, yell about it. 1337 */ 1338 if (((lock->lo_flags & LO_SLEEPABLE) != 0 && 1339 (lock1->li_lock->lo_flags & LO_SLEEPABLE) == 0)) 1340 witness_output( 1341 "lock order reversal: (sleepable after non-sleepable)\n"); 1342 else if ((lock1->li_lock->lo_flags & LO_SLEEPABLE) == 0 1343 && lock == &Giant.lock_object) 1344 witness_output( 1345 "lock order reversal: (Giant after non-sleepable)\n"); 1346 else 1347 witness_output("lock order reversal:\n"); 1348 1349 /* 1350 * Try to locate an earlier lock with 1351 * witness w in our list. 1352 */ 1353 do { 1354 lock2 = &lle->ll_children[i]; 1355 MPASS(lock2->li_lock != NULL); 1356 if (lock2->li_lock->lo_witness == w) 1357 break; 1358 if (i == 0 && lle->ll_next != NULL) { 1359 lle = lle->ll_next; 1360 i = lle->ll_count - 1; 1361 MPASS(i >= 0 && i < LOCK_NCHILDREN); 1362 } else 1363 i--; 1364 } while (i >= 0); 1365 if (i < 0) { 1366 witness_output(" 1st %p %s (%s) @ %s:%d\n", 1367 lock1->li_lock, lock1->li_lock->lo_name, 1368 w1->w_name, fixup_filename(lock1->li_file), 1369 lock1->li_line); 1370 witness_output(" 2nd %p %s (%s) @ %s:%d\n", lock, 1371 lock->lo_name, w->w_name, 1372 fixup_filename(file), line); 1373 } else { 1374 witness_output(" 1st %p %s (%s) @ %s:%d\n", 1375 lock2->li_lock, lock2->li_lock->lo_name, 1376 lock2->li_lock->lo_witness->w_name, 1377 fixup_filename(lock2->li_file), 1378 lock2->li_line); 1379 witness_output(" 2nd %p %s (%s) @ %s:%d\n", 1380 lock1->li_lock, lock1->li_lock->lo_name, 1381 w1->w_name, fixup_filename(lock1->li_file), 1382 lock1->li_line); 1383 witness_output(" 3rd %p %s (%s) @ %s:%d\n", lock, 1384 lock->lo_name, w->w_name, 1385 fixup_filename(file), line); 1386 } 1387 witness_debugger(1, __func__); 1388 return; 1389 } 1390 } 1391 1392 /* 1393 * If requested, build a new lock order. However, don't build a new 1394 * relationship between a sleepable lock and Giant if it is in the 1395 * wrong direction. The correct lock order is that sleepable locks 1396 * always come before Giant. 1397 */ 1398 if (flags & LOP_NEWORDER && 1399 !(plock->li_lock == &Giant.lock_object && 1400 (lock->lo_flags & LO_SLEEPABLE) != 0)) { 1401 CTR3(KTR_WITNESS, "%s: adding %s as a child of %s", __func__, 1402 w->w_name, plock->li_lock->lo_witness->w_name); 1403 itismychild(plock->li_lock->lo_witness, w); 1404 } 1405 out: 1406 mtx_unlock_spin(&w_mtx); 1407 } 1408 1409 void 1410 witness_lock(struct lock_object *lock, int flags, const char *file, int line) 1411 { 1412 struct lock_list_entry **lock_list, *lle; 1413 struct lock_instance *instance; 1414 struct witness *w; 1415 struct thread *td; 1416 1417 if (witness_cold || witness_watch == -1 || lock->lo_witness == NULL || 1418 panicstr != NULL) 1419 return; 1420 w = lock->lo_witness; 1421 td = curthread; 1422 1423 /* Determine lock list for this lock. */ 1424 if (LOCK_CLASS(lock)->lc_flags & LC_SLEEPLOCK) 1425 lock_list = &td->td_sleeplocks; 1426 else 1427 lock_list = PCPU_PTR(spinlocks); 1428 1429 /* Check to see if we are recursing on a lock we already own. */ 1430 instance = find_instance(*lock_list, lock); 1431 if (instance != NULL) { 1432 instance->li_flags++; 1433 CTR4(KTR_WITNESS, "%s: pid %d recursed on %s r=%d", __func__, 1434 td->td_proc->p_pid, lock->lo_name, 1435 instance->li_flags & LI_RECURSEMASK); 1436 instance->li_file = file; 1437 instance->li_line = line; 1438 return; 1439 } 1440 1441 /* Update per-witness last file and line acquire. */ 1442 w->w_file = file; 1443 w->w_line = line; 1444 1445 /* Find the next open lock instance in the list and fill it. */ 1446 lle = *lock_list; 1447 if (lle == NULL || lle->ll_count == LOCK_NCHILDREN) { 1448 lle = witness_lock_list_get(); 1449 if (lle == NULL) 1450 return; 1451 lle->ll_next = *lock_list; 1452 CTR3(KTR_WITNESS, "%s: pid %d added lle %p", __func__, 1453 td->td_proc->p_pid, lle); 1454 *lock_list = lle; 1455 } 1456 instance = &lle->ll_children[lle->ll_count++]; 1457 instance->li_lock = lock; 1458 instance->li_line = line; 1459 instance->li_file = file; 1460 if ((flags & LOP_EXCLUSIVE) != 0) 1461 instance->li_flags = LI_EXCLUSIVE; 1462 else 1463 instance->li_flags = 0; 1464 CTR4(KTR_WITNESS, "%s: pid %d added %s as lle[%d]", __func__, 1465 td->td_proc->p_pid, lock->lo_name, lle->ll_count - 1); 1466 } 1467 1468 void 1469 witness_upgrade(struct lock_object *lock, int flags, const char *file, int line) 1470 { 1471 struct lock_instance *instance; 1472 struct lock_class *class; 1473 1474 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); 1475 if (lock->lo_witness == NULL || witness_watch == -1 || panicstr != NULL) 1476 return; 1477 class = LOCK_CLASS(lock); 1478 if (witness_watch) { 1479 if ((lock->lo_flags & LO_UPGRADABLE) == 0) 1480 kassert_panic( 1481 "upgrade of non-upgradable lock (%s) %s @ %s:%d", 1482 class->lc_name, lock->lo_name, 1483 fixup_filename(file), line); 1484 if ((class->lc_flags & LC_SLEEPLOCK) == 0) 1485 kassert_panic( 1486 "upgrade of non-sleep lock (%s) %s @ %s:%d", 1487 class->lc_name, lock->lo_name, 1488 fixup_filename(file), line); 1489 } 1490 instance = find_instance(curthread->td_sleeplocks, lock); 1491 if (instance == NULL) { 1492 kassert_panic("upgrade of unlocked lock (%s) %s @ %s:%d", 1493 class->lc_name, lock->lo_name, 1494 fixup_filename(file), line); 1495 return; 1496 } 1497 if (witness_watch) { 1498 if ((instance->li_flags & LI_EXCLUSIVE) != 0) 1499 kassert_panic( 1500 "upgrade of exclusive lock (%s) %s @ %s:%d", 1501 class->lc_name, lock->lo_name, 1502 fixup_filename(file), line); 1503 if ((instance->li_flags & LI_RECURSEMASK) != 0) 1504 kassert_panic( 1505 "upgrade of recursed lock (%s) %s r=%d @ %s:%d", 1506 class->lc_name, lock->lo_name, 1507 instance->li_flags & LI_RECURSEMASK, 1508 fixup_filename(file), line); 1509 } 1510 instance->li_flags |= LI_EXCLUSIVE; 1511 } 1512 1513 void 1514 witness_downgrade(struct lock_object *lock, int flags, const char *file, 1515 int line) 1516 { 1517 struct lock_instance *instance; 1518 struct lock_class *class; 1519 1520 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); 1521 if (lock->lo_witness == NULL || witness_watch == -1 || panicstr != NULL) 1522 return; 1523 class = LOCK_CLASS(lock); 1524 if (witness_watch) { 1525 if ((lock->lo_flags & LO_UPGRADABLE) == 0) 1526 kassert_panic( 1527 "downgrade of non-upgradable lock (%s) %s @ %s:%d", 1528 class->lc_name, lock->lo_name, 1529 fixup_filename(file), line); 1530 if ((class->lc_flags & LC_SLEEPLOCK) == 0) 1531 kassert_panic( 1532 "downgrade of non-sleep lock (%s) %s @ %s:%d", 1533 class->lc_name, lock->lo_name, 1534 fixup_filename(file), line); 1535 } 1536 instance = find_instance(curthread->td_sleeplocks, lock); 1537 if (instance == NULL) { 1538 kassert_panic("downgrade of unlocked lock (%s) %s @ %s:%d", 1539 class->lc_name, lock->lo_name, 1540 fixup_filename(file), line); 1541 return; 1542 } 1543 if (witness_watch) { 1544 if ((instance->li_flags & LI_EXCLUSIVE) == 0) 1545 kassert_panic( 1546 "downgrade of shared lock (%s) %s @ %s:%d", 1547 class->lc_name, lock->lo_name, 1548 fixup_filename(file), line); 1549 if ((instance->li_flags & LI_RECURSEMASK) != 0) 1550 kassert_panic( 1551 "downgrade of recursed lock (%s) %s r=%d @ %s:%d", 1552 class->lc_name, lock->lo_name, 1553 instance->li_flags & LI_RECURSEMASK, 1554 fixup_filename(file), line); 1555 } 1556 instance->li_flags &= ~LI_EXCLUSIVE; 1557 } 1558 1559 void 1560 witness_unlock(struct lock_object *lock, int flags, const char *file, int line) 1561 { 1562 struct lock_list_entry **lock_list, *lle; 1563 struct lock_instance *instance; 1564 struct lock_class *class; 1565 struct thread *td; 1566 register_t s; 1567 int i, j; 1568 1569 if (witness_cold || lock->lo_witness == NULL || panicstr != NULL) 1570 return; 1571 td = curthread; 1572 class = LOCK_CLASS(lock); 1573 1574 /* Find lock instance associated with this lock. */ 1575 if (class->lc_flags & LC_SLEEPLOCK) 1576 lock_list = &td->td_sleeplocks; 1577 else 1578 lock_list = PCPU_PTR(spinlocks); 1579 lle = *lock_list; 1580 for (; *lock_list != NULL; lock_list = &(*lock_list)->ll_next) 1581 for (i = 0; i < (*lock_list)->ll_count; i++) { 1582 instance = &(*lock_list)->ll_children[i]; 1583 if (instance->li_lock == lock) 1584 goto found; 1585 } 1586 1587 /* 1588 * When disabling WITNESS through witness_watch we could end up in 1589 * having registered locks in the td_sleeplocks queue. 1590 * We have to make sure we flush these queues, so just search for 1591 * eventual register locks and remove them. 1592 */ 1593 if (witness_watch > 0) { 1594 kassert_panic("lock (%s) %s not locked @ %s:%d", class->lc_name, 1595 lock->lo_name, fixup_filename(file), line); 1596 return; 1597 } else { 1598 return; 1599 } 1600 found: 1601 1602 /* First, check for shared/exclusive mismatches. */ 1603 if ((instance->li_flags & LI_EXCLUSIVE) != 0 && witness_watch > 0 && 1604 (flags & LOP_EXCLUSIVE) == 0) { 1605 witness_output("shared unlock of (%s) %s @ %s:%d\n", 1606 class->lc_name, lock->lo_name, fixup_filename(file), line); 1607 witness_output("while exclusively locked from %s:%d\n", 1608 fixup_filename(instance->li_file), instance->li_line); 1609 kassert_panic("excl->ushare"); 1610 } 1611 if ((instance->li_flags & LI_EXCLUSIVE) == 0 && witness_watch > 0 && 1612 (flags & LOP_EXCLUSIVE) != 0) { 1613 witness_output("exclusive unlock of (%s) %s @ %s:%d\n", 1614 class->lc_name, lock->lo_name, fixup_filename(file), line); 1615 witness_output("while share locked from %s:%d\n", 1616 fixup_filename(instance->li_file), 1617 instance->li_line); 1618 kassert_panic("share->uexcl"); 1619 } 1620 /* If we are recursed, unrecurse. */ 1621 if ((instance->li_flags & LI_RECURSEMASK) > 0) { 1622 CTR4(KTR_WITNESS, "%s: pid %d unrecursed on %s r=%d", __func__, 1623 td->td_proc->p_pid, instance->li_lock->lo_name, 1624 instance->li_flags); 1625 instance->li_flags--; 1626 return; 1627 } 1628 /* The lock is now being dropped, check for NORELEASE flag */ 1629 if ((instance->li_flags & LI_NORELEASE) != 0 && witness_watch > 0) { 1630 witness_output("forbidden unlock of (%s) %s @ %s:%d\n", 1631 class->lc_name, lock->lo_name, fixup_filename(file), line); 1632 kassert_panic("lock marked norelease"); 1633 } 1634 1635 /* Otherwise, remove this item from the list. */ 1636 s = intr_disable(); 1637 CTR4(KTR_WITNESS, "%s: pid %d removed %s from lle[%d]", __func__, 1638 td->td_proc->p_pid, instance->li_lock->lo_name, 1639 (*lock_list)->ll_count - 1); 1640 for (j = i; j < (*lock_list)->ll_count - 1; j++) 1641 (*lock_list)->ll_children[j] = 1642 (*lock_list)->ll_children[j + 1]; 1643 (*lock_list)->ll_count--; 1644 intr_restore(s); 1645 1646 /* 1647 * In order to reduce contention on w_mtx, we want to keep always an 1648 * head object into lists so that frequent allocation from the 1649 * free witness pool (and subsequent locking) is avoided. 1650 * In order to maintain the current code simple, when the head 1651 * object is totally unloaded it means also that we do not have 1652 * further objects in the list, so the list ownership needs to be 1653 * hand over to another object if the current head needs to be freed. 1654 */ 1655 if ((*lock_list)->ll_count == 0) { 1656 if (*lock_list == lle) { 1657 if (lle->ll_next == NULL) 1658 return; 1659 } else 1660 lle = *lock_list; 1661 *lock_list = lle->ll_next; 1662 CTR3(KTR_WITNESS, "%s: pid %d removed lle %p", __func__, 1663 td->td_proc->p_pid, lle); 1664 witness_lock_list_free(lle); 1665 } 1666 } 1667 1668 void 1669 witness_thread_exit(struct thread *td) 1670 { 1671 struct lock_list_entry *lle; 1672 int i, n; 1673 1674 lle = td->td_sleeplocks; 1675 if (lle == NULL || panicstr != NULL) 1676 return; 1677 if (lle->ll_count != 0) { 1678 for (n = 0; lle != NULL; lle = lle->ll_next) 1679 for (i = lle->ll_count - 1; i >= 0; i--) { 1680 if (n == 0) 1681 witness_output( 1682 "Thread %p exiting with the following locks held:\n", td); 1683 n++; 1684 witness_list_lock(&lle->ll_children[i], 1685 witness_output); 1686 1687 } 1688 kassert_panic( 1689 "Thread %p cannot exit while holding sleeplocks\n", td); 1690 } 1691 witness_lock_list_free(lle); 1692 } 1693 1694 /* 1695 * Warn if any locks other than 'lock' are held. Flags can be passed in to 1696 * exempt Giant and sleepable locks from the checks as well. If any 1697 * non-exempt locks are held, then a supplied message is printed to the 1698 * output channel along with a list of the offending locks. If indicated in the 1699 * flags then a failure results in a panic as well. 1700 */ 1701 int 1702 witness_warn(int flags, struct lock_object *lock, const char *fmt, ...) 1703 { 1704 struct lock_list_entry *lock_list, *lle; 1705 struct lock_instance *lock1; 1706 struct thread *td; 1707 va_list ap; 1708 int i, n; 1709 1710 if (witness_cold || witness_watch < 1 || panicstr != NULL) 1711 return (0); 1712 n = 0; 1713 td = curthread; 1714 for (lle = td->td_sleeplocks; lle != NULL; lle = lle->ll_next) 1715 for (i = lle->ll_count - 1; i >= 0; i--) { 1716 lock1 = &lle->ll_children[i]; 1717 if (lock1->li_lock == lock) 1718 continue; 1719 if (flags & WARN_GIANTOK && 1720 lock1->li_lock == &Giant.lock_object) 1721 continue; 1722 if (flags & WARN_SLEEPOK && 1723 (lock1->li_lock->lo_flags & LO_SLEEPABLE) != 0) 1724 continue; 1725 if (n == 0) { 1726 va_start(ap, fmt); 1727 witness_voutput(fmt, ap); 1728 va_end(ap); 1729 witness_output( 1730 " with the following %slocks held:\n", 1731 (flags & WARN_SLEEPOK) != 0 ? 1732 "non-sleepable " : ""); 1733 } 1734 n++; 1735 witness_list_lock(lock1, witness_output); 1736 } 1737 1738 /* 1739 * Pin the thread in order to avoid problems with thread migration. 1740 * Once that all verifies are passed about spinlocks ownership, 1741 * the thread is in a safe path and it can be unpinned. 1742 */ 1743 sched_pin(); 1744 lock_list = PCPU_GET(spinlocks); 1745 if (lock_list != NULL && lock_list->ll_count != 0) { 1746 sched_unpin(); 1747 1748 /* 1749 * We should only have one spinlock and as long as 1750 * the flags cannot match for this locks class, 1751 * check if the first spinlock is the one curthread 1752 * should hold. 1753 */ 1754 lock1 = &lock_list->ll_children[lock_list->ll_count - 1]; 1755 if (lock_list->ll_count == 1 && lock_list->ll_next == NULL && 1756 lock1->li_lock == lock && n == 0) 1757 return (0); 1758 1759 va_start(ap, fmt); 1760 witness_voutput(fmt, ap); 1761 va_end(ap); 1762 witness_output(" with the following %slocks held:\n", 1763 (flags & WARN_SLEEPOK) != 0 ? "non-sleepable " : ""); 1764 n += witness_list_locks(&lock_list, witness_output); 1765 } else 1766 sched_unpin(); 1767 if (flags & WARN_PANIC && n) 1768 kassert_panic("%s", __func__); 1769 else 1770 witness_debugger(n, __func__); 1771 return (n); 1772 } 1773 1774 const char * 1775 witness_file(struct lock_object *lock) 1776 { 1777 struct witness *w; 1778 1779 if (witness_cold || witness_watch < 1 || lock->lo_witness == NULL) 1780 return ("?"); 1781 w = lock->lo_witness; 1782 return (w->w_file); 1783 } 1784 1785 int 1786 witness_line(struct lock_object *lock) 1787 { 1788 struct witness *w; 1789 1790 if (witness_cold || witness_watch < 1 || lock->lo_witness == NULL) 1791 return (0); 1792 w = lock->lo_witness; 1793 return (w->w_line); 1794 } 1795 1796 static struct witness * 1797 enroll(const char *description, struct lock_class *lock_class) 1798 { 1799 struct witness *w; 1800 struct witness_list *typelist; 1801 1802 MPASS(description != NULL); 1803 1804 if (witness_watch == -1 || panicstr != NULL) 1805 return (NULL); 1806 if ((lock_class->lc_flags & LC_SPINLOCK)) { 1807 if (witness_skipspin) 1808 return (NULL); 1809 else 1810 typelist = &w_spin; 1811 } else if ((lock_class->lc_flags & LC_SLEEPLOCK)) { 1812 typelist = &w_sleep; 1813 } else { 1814 kassert_panic("lock class %s is not sleep or spin", 1815 lock_class->lc_name); 1816 return (NULL); 1817 } 1818 1819 mtx_lock_spin(&w_mtx); 1820 w = witness_hash_get(description); 1821 if (w) 1822 goto found; 1823 if ((w = witness_get()) == NULL) 1824 return (NULL); 1825 MPASS(strlen(description) < MAX_W_NAME); 1826 strcpy(w->w_name, description); 1827 w->w_class = lock_class; 1828 w->w_refcount = 1; 1829 STAILQ_INSERT_HEAD(&w_all, w, w_list); 1830 if (lock_class->lc_flags & LC_SPINLOCK) { 1831 STAILQ_INSERT_HEAD(&w_spin, w, w_typelist); 1832 w_spin_cnt++; 1833 } else if (lock_class->lc_flags & LC_SLEEPLOCK) { 1834 STAILQ_INSERT_HEAD(&w_sleep, w, w_typelist); 1835 w_sleep_cnt++; 1836 } 1837 1838 /* Insert new witness into the hash */ 1839 witness_hash_put(w); 1840 witness_increment_graph_generation(); 1841 mtx_unlock_spin(&w_mtx); 1842 return (w); 1843 found: 1844 w->w_refcount++; 1845 mtx_unlock_spin(&w_mtx); 1846 if (lock_class != w->w_class) 1847 kassert_panic( 1848 "lock (%s) %s does not match earlier (%s) lock", 1849 description, lock_class->lc_name, 1850 w->w_class->lc_name); 1851 return (w); 1852 } 1853 1854 static void 1855 depart(struct witness *w) 1856 { 1857 struct witness_list *list; 1858 1859 MPASS(w->w_refcount == 0); 1860 if (w->w_class->lc_flags & LC_SLEEPLOCK) { 1861 list = &w_sleep; 1862 w_sleep_cnt--; 1863 } else { 1864 list = &w_spin; 1865 w_spin_cnt--; 1866 } 1867 /* 1868 * Set file to NULL as it may point into a loadable module. 1869 */ 1870 w->w_file = NULL; 1871 w->w_line = 0; 1872 witness_increment_graph_generation(); 1873 } 1874 1875 1876 static void 1877 adopt(struct witness *parent, struct witness *child) 1878 { 1879 int pi, ci, i, j; 1880 1881 if (witness_cold == 0) 1882 mtx_assert(&w_mtx, MA_OWNED); 1883 1884 /* If the relationship is already known, there's no work to be done. */ 1885 if (isitmychild(parent, child)) 1886 return; 1887 1888 /* When the structure of the graph changes, bump up the generation. */ 1889 witness_increment_graph_generation(); 1890 1891 /* 1892 * The hard part ... create the direct relationship, then propagate all 1893 * indirect relationships. 1894 */ 1895 pi = parent->w_index; 1896 ci = child->w_index; 1897 WITNESS_INDEX_ASSERT(pi); 1898 WITNESS_INDEX_ASSERT(ci); 1899 MPASS(pi != ci); 1900 w_rmatrix[pi][ci] |= WITNESS_PARENT; 1901 w_rmatrix[ci][pi] |= WITNESS_CHILD; 1902 1903 /* 1904 * If parent was not already an ancestor of child, 1905 * then we increment the descendant and ancestor counters. 1906 */ 1907 if ((w_rmatrix[pi][ci] & WITNESS_ANCESTOR) == 0) { 1908 parent->w_num_descendants++; 1909 child->w_num_ancestors++; 1910 } 1911 1912 /* 1913 * Find each ancestor of 'pi'. Note that 'pi' itself is counted as 1914 * an ancestor of 'pi' during this loop. 1915 */ 1916 for (i = 1; i <= w_max_used_index; i++) { 1917 if ((w_rmatrix[i][pi] & WITNESS_ANCESTOR_MASK) == 0 && 1918 (i != pi)) 1919 continue; 1920 1921 /* Find each descendant of 'i' and mark it as a descendant. */ 1922 for (j = 1; j <= w_max_used_index; j++) { 1923 1924 /* 1925 * Skip children that are already marked as 1926 * descendants of 'i'. 1927 */ 1928 if (w_rmatrix[i][j] & WITNESS_ANCESTOR_MASK) 1929 continue; 1930 1931 /* 1932 * We are only interested in descendants of 'ci'. Note 1933 * that 'ci' itself is counted as a descendant of 'ci'. 1934 */ 1935 if ((w_rmatrix[ci][j] & WITNESS_ANCESTOR_MASK) == 0 && 1936 (j != ci)) 1937 continue; 1938 w_rmatrix[i][j] |= WITNESS_ANCESTOR; 1939 w_rmatrix[j][i] |= WITNESS_DESCENDANT; 1940 w_data[i].w_num_descendants++; 1941 w_data[j].w_num_ancestors++; 1942 1943 /* 1944 * Make sure we aren't marking a node as both an 1945 * ancestor and descendant. We should have caught 1946 * this as a lock order reversal earlier. 1947 */ 1948 if ((w_rmatrix[i][j] & WITNESS_ANCESTOR_MASK) && 1949 (w_rmatrix[i][j] & WITNESS_DESCENDANT_MASK)) { 1950 printf("witness rmatrix paradox! [%d][%d]=%d " 1951 "both ancestor and descendant\n", 1952 i, j, w_rmatrix[i][j]); 1953 kdb_backtrace(); 1954 printf("Witness disabled.\n"); 1955 witness_watch = -1; 1956 } 1957 if ((w_rmatrix[j][i] & WITNESS_ANCESTOR_MASK) && 1958 (w_rmatrix[j][i] & WITNESS_DESCENDANT_MASK)) { 1959 printf("witness rmatrix paradox! [%d][%d]=%d " 1960 "both ancestor and descendant\n", 1961 j, i, w_rmatrix[j][i]); 1962 kdb_backtrace(); 1963 printf("Witness disabled.\n"); 1964 witness_watch = -1; 1965 } 1966 } 1967 } 1968 } 1969 1970 static void 1971 itismychild(struct witness *parent, struct witness *child) 1972 { 1973 int unlocked; 1974 1975 MPASS(child != NULL && parent != NULL); 1976 if (witness_cold == 0) 1977 mtx_assert(&w_mtx, MA_OWNED); 1978 1979 if (!witness_lock_type_equal(parent, child)) { 1980 if (witness_cold == 0) { 1981 unlocked = 1; 1982 mtx_unlock_spin(&w_mtx); 1983 } else { 1984 unlocked = 0; 1985 } 1986 kassert_panic( 1987 "%s: parent \"%s\" (%s) and child \"%s\" (%s) are not " 1988 "the same lock type", __func__, parent->w_name, 1989 parent->w_class->lc_name, child->w_name, 1990 child->w_class->lc_name); 1991 if (unlocked) 1992 mtx_lock_spin(&w_mtx); 1993 } 1994 adopt(parent, child); 1995 } 1996 1997 /* 1998 * Generic code for the isitmy*() functions. The rmask parameter is the 1999 * expected relationship of w1 to w2. 2000 */ 2001 static int 2002 _isitmyx(struct witness *w1, struct witness *w2, int rmask, const char *fname) 2003 { 2004 unsigned char r1, r2; 2005 int i1, i2; 2006 2007 i1 = w1->w_index; 2008 i2 = w2->w_index; 2009 WITNESS_INDEX_ASSERT(i1); 2010 WITNESS_INDEX_ASSERT(i2); 2011 r1 = w_rmatrix[i1][i2] & WITNESS_RELATED_MASK; 2012 r2 = w_rmatrix[i2][i1] & WITNESS_RELATED_MASK; 2013 2014 /* The flags on one better be the inverse of the flags on the other */ 2015 if (!((WITNESS_ATOD(r1) == r2 && WITNESS_DTOA(r2) == r1) || 2016 (WITNESS_DTOA(r1) == r2 && WITNESS_ATOD(r2) == r1))) { 2017 /* Don't squawk if we're potentially racing with an update. */ 2018 if (!mtx_owned(&w_mtx)) 2019 return (0); 2020 printf("%s: rmatrix mismatch between %s (index %d) and %s " 2021 "(index %d): w_rmatrix[%d][%d] == %hhx but " 2022 "w_rmatrix[%d][%d] == %hhx\n", 2023 fname, w1->w_name, i1, w2->w_name, i2, i1, i2, r1, 2024 i2, i1, r2); 2025 kdb_backtrace(); 2026 printf("Witness disabled.\n"); 2027 witness_watch = -1; 2028 } 2029 return (r1 & rmask); 2030 } 2031 2032 /* 2033 * Checks if @child is a direct child of @parent. 2034 */ 2035 static int 2036 isitmychild(struct witness *parent, struct witness *child) 2037 { 2038 2039 return (_isitmyx(parent, child, WITNESS_PARENT, __func__)); 2040 } 2041 2042 /* 2043 * Checks if @descendant is a direct or inderect descendant of @ancestor. 2044 */ 2045 static int 2046 isitmydescendant(struct witness *ancestor, struct witness *descendant) 2047 { 2048 2049 return (_isitmyx(ancestor, descendant, WITNESS_ANCESTOR_MASK, 2050 __func__)); 2051 } 2052 2053 #ifdef BLESSING 2054 static int 2055 blessed(struct witness *w1, struct witness *w2) 2056 { 2057 int i; 2058 struct witness_blessed *b; 2059 2060 for (i = 0; i < nitems(blessed_list); i++) { 2061 b = &blessed_list[i]; 2062 if (strcmp(w1->w_name, b->b_lock1) == 0) { 2063 if (strcmp(w2->w_name, b->b_lock2) == 0) 2064 return (1); 2065 continue; 2066 } 2067 if (strcmp(w1->w_name, b->b_lock2) == 0) 2068 if (strcmp(w2->w_name, b->b_lock1) == 0) 2069 return (1); 2070 } 2071 return (0); 2072 } 2073 #endif 2074 2075 static struct witness * 2076 witness_get(void) 2077 { 2078 struct witness *w; 2079 int index; 2080 2081 if (witness_cold == 0) 2082 mtx_assert(&w_mtx, MA_OWNED); 2083 2084 if (witness_watch == -1) { 2085 mtx_unlock_spin(&w_mtx); 2086 return (NULL); 2087 } 2088 if (STAILQ_EMPTY(&w_free)) { 2089 witness_watch = -1; 2090 mtx_unlock_spin(&w_mtx); 2091 printf("WITNESS: unable to allocate a new witness object\n"); 2092 return (NULL); 2093 } 2094 w = STAILQ_FIRST(&w_free); 2095 STAILQ_REMOVE_HEAD(&w_free, w_list); 2096 w_free_cnt--; 2097 index = w->w_index; 2098 MPASS(index > 0 && index == w_max_used_index+1 && 2099 index < witness_count); 2100 bzero(w, sizeof(*w)); 2101 w->w_index = index; 2102 if (index > w_max_used_index) 2103 w_max_used_index = index; 2104 return (w); 2105 } 2106 2107 static void 2108 witness_free(struct witness *w) 2109 { 2110 2111 STAILQ_INSERT_HEAD(&w_free, w, w_list); 2112 w_free_cnt++; 2113 } 2114 2115 static struct lock_list_entry * 2116 witness_lock_list_get(void) 2117 { 2118 struct lock_list_entry *lle; 2119 2120 if (witness_watch == -1) 2121 return (NULL); 2122 mtx_lock_spin(&w_mtx); 2123 lle = w_lock_list_free; 2124 if (lle == NULL) { 2125 witness_watch = -1; 2126 mtx_unlock_spin(&w_mtx); 2127 printf("%s: witness exhausted\n", __func__); 2128 return (NULL); 2129 } 2130 w_lock_list_free = lle->ll_next; 2131 mtx_unlock_spin(&w_mtx); 2132 bzero(lle, sizeof(*lle)); 2133 return (lle); 2134 } 2135 2136 static void 2137 witness_lock_list_free(struct lock_list_entry *lle) 2138 { 2139 2140 mtx_lock_spin(&w_mtx); 2141 lle->ll_next = w_lock_list_free; 2142 w_lock_list_free = lle; 2143 mtx_unlock_spin(&w_mtx); 2144 } 2145 2146 static struct lock_instance * 2147 find_instance(struct lock_list_entry *list, const struct lock_object *lock) 2148 { 2149 struct lock_list_entry *lle; 2150 struct lock_instance *instance; 2151 int i; 2152 2153 for (lle = list; lle != NULL; lle = lle->ll_next) 2154 for (i = lle->ll_count - 1; i >= 0; i--) { 2155 instance = &lle->ll_children[i]; 2156 if (instance->li_lock == lock) 2157 return (instance); 2158 } 2159 return (NULL); 2160 } 2161 2162 static void 2163 witness_list_lock(struct lock_instance *instance, 2164 int (*prnt)(const char *fmt, ...)) 2165 { 2166 struct lock_object *lock; 2167 2168 lock = instance->li_lock; 2169 prnt("%s %s %s", (instance->li_flags & LI_EXCLUSIVE) != 0 ? 2170 "exclusive" : "shared", LOCK_CLASS(lock)->lc_name, lock->lo_name); 2171 if (lock->lo_witness->w_name != lock->lo_name) 2172 prnt(" (%s)", lock->lo_witness->w_name); 2173 prnt(" r = %d (%p) locked @ %s:%d\n", 2174 instance->li_flags & LI_RECURSEMASK, lock, 2175 fixup_filename(instance->li_file), instance->li_line); 2176 } 2177 2178 static int 2179 witness_output(const char *fmt, ...) 2180 { 2181 va_list ap; 2182 int ret; 2183 2184 va_start(ap, fmt); 2185 ret = witness_voutput(fmt, ap); 2186 va_end(ap); 2187 return (ret); 2188 } 2189 2190 static int 2191 witness_voutput(const char *fmt, va_list ap) 2192 { 2193 int ret; 2194 2195 ret = 0; 2196 switch (witness_channel) { 2197 case WITNESS_CONSOLE: 2198 ret = vprintf(fmt, ap); 2199 break; 2200 case WITNESS_LOG: 2201 vlog(LOG_NOTICE, fmt, ap); 2202 break; 2203 case WITNESS_NONE: 2204 break; 2205 } 2206 return (ret); 2207 } 2208 2209 #ifdef DDB 2210 static int 2211 witness_thread_has_locks(struct thread *td) 2212 { 2213 2214 if (td->td_sleeplocks == NULL) 2215 return (0); 2216 return (td->td_sleeplocks->ll_count != 0); 2217 } 2218 2219 static int 2220 witness_proc_has_locks(struct proc *p) 2221 { 2222 struct thread *td; 2223 2224 FOREACH_THREAD_IN_PROC(p, td) { 2225 if (witness_thread_has_locks(td)) 2226 return (1); 2227 } 2228 return (0); 2229 } 2230 #endif 2231 2232 int 2233 witness_list_locks(struct lock_list_entry **lock_list, 2234 int (*prnt)(const char *fmt, ...)) 2235 { 2236 struct lock_list_entry *lle; 2237 int i, nheld; 2238 2239 nheld = 0; 2240 for (lle = *lock_list; lle != NULL; lle = lle->ll_next) 2241 for (i = lle->ll_count - 1; i >= 0; i--) { 2242 witness_list_lock(&lle->ll_children[i], prnt); 2243 nheld++; 2244 } 2245 return (nheld); 2246 } 2247 2248 /* 2249 * This is a bit risky at best. We call this function when we have timed 2250 * out acquiring a spin lock, and we assume that the other CPU is stuck 2251 * with this lock held. So, we go groveling around in the other CPU's 2252 * per-cpu data to try to find the lock instance for this spin lock to 2253 * see when it was last acquired. 2254 */ 2255 void 2256 witness_display_spinlock(struct lock_object *lock, struct thread *owner, 2257 int (*prnt)(const char *fmt, ...)) 2258 { 2259 struct lock_instance *instance; 2260 struct pcpu *pc; 2261 2262 if (owner->td_critnest == 0 || owner->td_oncpu == NOCPU) 2263 return; 2264 pc = pcpu_find(owner->td_oncpu); 2265 instance = find_instance(pc->pc_spinlocks, lock); 2266 if (instance != NULL) 2267 witness_list_lock(instance, prnt); 2268 } 2269 2270 void 2271 witness_save(struct lock_object *lock, const char **filep, int *linep) 2272 { 2273 struct lock_list_entry *lock_list; 2274 struct lock_instance *instance; 2275 struct lock_class *class; 2276 2277 /* 2278 * This function is used independently in locking code to deal with 2279 * Giant, SCHEDULER_STOPPED() check can be removed here after Giant 2280 * is gone. 2281 */ 2282 if (SCHEDULER_STOPPED()) 2283 return; 2284 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); 2285 if (lock->lo_witness == NULL || witness_watch == -1 || panicstr != NULL) 2286 return; 2287 class = LOCK_CLASS(lock); 2288 if (class->lc_flags & LC_SLEEPLOCK) 2289 lock_list = curthread->td_sleeplocks; 2290 else { 2291 if (witness_skipspin) 2292 return; 2293 lock_list = PCPU_GET(spinlocks); 2294 } 2295 instance = find_instance(lock_list, lock); 2296 if (instance == NULL) { 2297 kassert_panic("%s: lock (%s) %s not locked", __func__, 2298 class->lc_name, lock->lo_name); 2299 return; 2300 } 2301 *filep = instance->li_file; 2302 *linep = instance->li_line; 2303 } 2304 2305 void 2306 witness_restore(struct lock_object *lock, const char *file, int line) 2307 { 2308 struct lock_list_entry *lock_list; 2309 struct lock_instance *instance; 2310 struct lock_class *class; 2311 2312 /* 2313 * This function is used independently in locking code to deal with 2314 * Giant, SCHEDULER_STOPPED() check can be removed here after Giant 2315 * is gone. 2316 */ 2317 if (SCHEDULER_STOPPED()) 2318 return; 2319 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); 2320 if (lock->lo_witness == NULL || witness_watch == -1 || panicstr != NULL) 2321 return; 2322 class = LOCK_CLASS(lock); 2323 if (class->lc_flags & LC_SLEEPLOCK) 2324 lock_list = curthread->td_sleeplocks; 2325 else { 2326 if (witness_skipspin) 2327 return; 2328 lock_list = PCPU_GET(spinlocks); 2329 } 2330 instance = find_instance(lock_list, lock); 2331 if (instance == NULL) 2332 kassert_panic("%s: lock (%s) %s not locked", __func__, 2333 class->lc_name, lock->lo_name); 2334 lock->lo_witness->w_file = file; 2335 lock->lo_witness->w_line = line; 2336 if (instance == NULL) 2337 return; 2338 instance->li_file = file; 2339 instance->li_line = line; 2340 } 2341 2342 void 2343 witness_assert(const struct lock_object *lock, int flags, const char *file, 2344 int line) 2345 { 2346 #ifdef INVARIANT_SUPPORT 2347 struct lock_instance *instance; 2348 struct lock_class *class; 2349 2350 if (lock->lo_witness == NULL || witness_watch < 1 || panicstr != NULL) 2351 return; 2352 class = LOCK_CLASS(lock); 2353 if ((class->lc_flags & LC_SLEEPLOCK) != 0) 2354 instance = find_instance(curthread->td_sleeplocks, lock); 2355 else if ((class->lc_flags & LC_SPINLOCK) != 0) 2356 instance = find_instance(PCPU_GET(spinlocks), lock); 2357 else { 2358 kassert_panic("Lock (%s) %s is not sleep or spin!", 2359 class->lc_name, lock->lo_name); 2360 return; 2361 } 2362 switch (flags) { 2363 case LA_UNLOCKED: 2364 if (instance != NULL) 2365 kassert_panic("Lock (%s) %s locked @ %s:%d.", 2366 class->lc_name, lock->lo_name, 2367 fixup_filename(file), line); 2368 break; 2369 case LA_LOCKED: 2370 case LA_LOCKED | LA_RECURSED: 2371 case LA_LOCKED | LA_NOTRECURSED: 2372 case LA_SLOCKED: 2373 case LA_SLOCKED | LA_RECURSED: 2374 case LA_SLOCKED | LA_NOTRECURSED: 2375 case LA_XLOCKED: 2376 case LA_XLOCKED | LA_RECURSED: 2377 case LA_XLOCKED | LA_NOTRECURSED: 2378 if (instance == NULL) { 2379 kassert_panic("Lock (%s) %s not locked @ %s:%d.", 2380 class->lc_name, lock->lo_name, 2381 fixup_filename(file), line); 2382 break; 2383 } 2384 if ((flags & LA_XLOCKED) != 0 && 2385 (instance->li_flags & LI_EXCLUSIVE) == 0) 2386 kassert_panic( 2387 "Lock (%s) %s not exclusively locked @ %s:%d.", 2388 class->lc_name, lock->lo_name, 2389 fixup_filename(file), line); 2390 if ((flags & LA_SLOCKED) != 0 && 2391 (instance->li_flags & LI_EXCLUSIVE) != 0) 2392 kassert_panic( 2393 "Lock (%s) %s exclusively locked @ %s:%d.", 2394 class->lc_name, lock->lo_name, 2395 fixup_filename(file), line); 2396 if ((flags & LA_RECURSED) != 0 && 2397 (instance->li_flags & LI_RECURSEMASK) == 0) 2398 kassert_panic("Lock (%s) %s not recursed @ %s:%d.", 2399 class->lc_name, lock->lo_name, 2400 fixup_filename(file), line); 2401 if ((flags & LA_NOTRECURSED) != 0 && 2402 (instance->li_flags & LI_RECURSEMASK) != 0) 2403 kassert_panic("Lock (%s) %s recursed @ %s:%d.", 2404 class->lc_name, lock->lo_name, 2405 fixup_filename(file), line); 2406 break; 2407 default: 2408 kassert_panic("Invalid lock assertion at %s:%d.", 2409 fixup_filename(file), line); 2410 2411 } 2412 #endif /* INVARIANT_SUPPORT */ 2413 } 2414 2415 static void 2416 witness_setflag(struct lock_object *lock, int flag, int set) 2417 { 2418 struct lock_list_entry *lock_list; 2419 struct lock_instance *instance; 2420 struct lock_class *class; 2421 2422 if (lock->lo_witness == NULL || witness_watch == -1 || panicstr != NULL) 2423 return; 2424 class = LOCK_CLASS(lock); 2425 if (class->lc_flags & LC_SLEEPLOCK) 2426 lock_list = curthread->td_sleeplocks; 2427 else { 2428 if (witness_skipspin) 2429 return; 2430 lock_list = PCPU_GET(spinlocks); 2431 } 2432 instance = find_instance(lock_list, lock); 2433 if (instance == NULL) { 2434 kassert_panic("%s: lock (%s) %s not locked", __func__, 2435 class->lc_name, lock->lo_name); 2436 return; 2437 } 2438 2439 if (set) 2440 instance->li_flags |= flag; 2441 else 2442 instance->li_flags &= ~flag; 2443 } 2444 2445 void 2446 witness_norelease(struct lock_object *lock) 2447 { 2448 2449 witness_setflag(lock, LI_NORELEASE, 1); 2450 } 2451 2452 void 2453 witness_releaseok(struct lock_object *lock) 2454 { 2455 2456 witness_setflag(lock, LI_NORELEASE, 0); 2457 } 2458 2459 #ifdef DDB 2460 static void 2461 witness_ddb_list(struct thread *td) 2462 { 2463 2464 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); 2465 KASSERT(kdb_active, ("%s: not in the debugger", __func__)); 2466 2467 if (witness_watch < 1) 2468 return; 2469 2470 witness_list_locks(&td->td_sleeplocks, db_printf); 2471 2472 /* 2473 * We only handle spinlocks if td == curthread. This is somewhat broken 2474 * if td is currently executing on some other CPU and holds spin locks 2475 * as we won't display those locks. If we had a MI way of getting 2476 * the per-cpu data for a given cpu then we could use 2477 * td->td_oncpu to get the list of spinlocks for this thread 2478 * and "fix" this. 2479 * 2480 * That still wouldn't really fix this unless we locked the scheduler 2481 * lock or stopped the other CPU to make sure it wasn't changing the 2482 * list out from under us. It is probably best to just not try to 2483 * handle threads on other CPU's for now. 2484 */ 2485 if (td == curthread && PCPU_GET(spinlocks) != NULL) 2486 witness_list_locks(PCPU_PTR(spinlocks), db_printf); 2487 } 2488 2489 DB_SHOW_COMMAND(locks, db_witness_list) 2490 { 2491 struct thread *td; 2492 2493 if (have_addr) 2494 td = db_lookup_thread(addr, true); 2495 else 2496 td = kdb_thread; 2497 witness_ddb_list(td); 2498 } 2499 2500 DB_SHOW_ALL_COMMAND(locks, db_witness_list_all) 2501 { 2502 struct thread *td; 2503 struct proc *p; 2504 2505 /* 2506 * It would be nice to list only threads and processes that actually 2507 * held sleep locks, but that information is currently not exported 2508 * by WITNESS. 2509 */ 2510 FOREACH_PROC_IN_SYSTEM(p) { 2511 if (!witness_proc_has_locks(p)) 2512 continue; 2513 FOREACH_THREAD_IN_PROC(p, td) { 2514 if (!witness_thread_has_locks(td)) 2515 continue; 2516 db_printf("Process %d (%s) thread %p (%d)\n", p->p_pid, 2517 p->p_comm, td, td->td_tid); 2518 witness_ddb_list(td); 2519 if (db_pager_quit) 2520 return; 2521 } 2522 } 2523 } 2524 DB_SHOW_ALIAS(alllocks, db_witness_list_all) 2525 2526 DB_SHOW_COMMAND(witness, db_witness_display) 2527 { 2528 2529 witness_ddb_display(db_printf); 2530 } 2531 #endif 2532 2533 static int 2534 sysctl_debug_witness_badstacks(SYSCTL_HANDLER_ARGS) 2535 { 2536 struct witness_lock_order_data *data1, *data2, *tmp_data1, *tmp_data2; 2537 struct witness *tmp_w1, *tmp_w2, *w1, *w2; 2538 struct sbuf *sb; 2539 u_int w_rmatrix1, w_rmatrix2; 2540 int error, generation, i, j; 2541 2542 tmp_data1 = NULL; 2543 tmp_data2 = NULL; 2544 tmp_w1 = NULL; 2545 tmp_w2 = NULL; 2546 if (witness_watch < 1) { 2547 error = SYSCTL_OUT(req, w_notrunning, sizeof(w_notrunning)); 2548 return (error); 2549 } 2550 if (witness_cold) { 2551 error = SYSCTL_OUT(req, w_stillcold, sizeof(w_stillcold)); 2552 return (error); 2553 } 2554 error = 0; 2555 sb = sbuf_new(NULL, NULL, badstack_sbuf_size, SBUF_AUTOEXTEND); 2556 if (sb == NULL) 2557 return (ENOMEM); 2558 2559 /* Allocate and init temporary storage space. */ 2560 tmp_w1 = malloc(sizeof(struct witness), M_TEMP, M_WAITOK | M_ZERO); 2561 tmp_w2 = malloc(sizeof(struct witness), M_TEMP, M_WAITOK | M_ZERO); 2562 tmp_data1 = malloc(sizeof(struct witness_lock_order_data), M_TEMP, 2563 M_WAITOK | M_ZERO); 2564 tmp_data2 = malloc(sizeof(struct witness_lock_order_data), M_TEMP, 2565 M_WAITOK | M_ZERO); 2566 stack_zero(&tmp_data1->wlod_stack); 2567 stack_zero(&tmp_data2->wlod_stack); 2568 2569 restart: 2570 mtx_lock_spin(&w_mtx); 2571 generation = w_generation; 2572 mtx_unlock_spin(&w_mtx); 2573 sbuf_printf(sb, "Number of known direct relationships is %d\n", 2574 w_lohash.wloh_count); 2575 for (i = 1; i < w_max_used_index; i++) { 2576 mtx_lock_spin(&w_mtx); 2577 if (generation != w_generation) { 2578 mtx_unlock_spin(&w_mtx); 2579 2580 /* The graph has changed, try again. */ 2581 req->oldidx = 0; 2582 sbuf_clear(sb); 2583 goto restart; 2584 } 2585 2586 w1 = &w_data[i]; 2587 if (w1->w_reversed == 0) { 2588 mtx_unlock_spin(&w_mtx); 2589 continue; 2590 } 2591 2592 /* Copy w1 locally so we can release the spin lock. */ 2593 *tmp_w1 = *w1; 2594 mtx_unlock_spin(&w_mtx); 2595 2596 if (tmp_w1->w_reversed == 0) 2597 continue; 2598 for (j = 1; j < w_max_used_index; j++) { 2599 if ((w_rmatrix[i][j] & WITNESS_REVERSAL) == 0 || i > j) 2600 continue; 2601 2602 mtx_lock_spin(&w_mtx); 2603 if (generation != w_generation) { 2604 mtx_unlock_spin(&w_mtx); 2605 2606 /* The graph has changed, try again. */ 2607 req->oldidx = 0; 2608 sbuf_clear(sb); 2609 goto restart; 2610 } 2611 2612 w2 = &w_data[j]; 2613 data1 = witness_lock_order_get(w1, w2); 2614 data2 = witness_lock_order_get(w2, w1); 2615 2616 /* 2617 * Copy information locally so we can release the 2618 * spin lock. 2619 */ 2620 *tmp_w2 = *w2; 2621 w_rmatrix1 = (unsigned int)w_rmatrix[i][j]; 2622 w_rmatrix2 = (unsigned int)w_rmatrix[j][i]; 2623 2624 if (data1) { 2625 stack_zero(&tmp_data1->wlod_stack); 2626 stack_copy(&data1->wlod_stack, 2627 &tmp_data1->wlod_stack); 2628 } 2629 if (data2 && data2 != data1) { 2630 stack_zero(&tmp_data2->wlod_stack); 2631 stack_copy(&data2->wlod_stack, 2632 &tmp_data2->wlod_stack); 2633 } 2634 mtx_unlock_spin(&w_mtx); 2635 2636 sbuf_printf(sb, 2637 "\nLock order reversal between \"%s\"(%s) and \"%s\"(%s)!\n", 2638 tmp_w1->w_name, tmp_w1->w_class->lc_name, 2639 tmp_w2->w_name, tmp_w2->w_class->lc_name); 2640 if (data1) { 2641 sbuf_printf(sb, 2642 "Lock order \"%s\"(%s) -> \"%s\"(%s) first seen at:\n", 2643 tmp_w1->w_name, tmp_w1->w_class->lc_name, 2644 tmp_w2->w_name, tmp_w2->w_class->lc_name); 2645 stack_sbuf_print(sb, &tmp_data1->wlod_stack); 2646 sbuf_printf(sb, "\n"); 2647 } 2648 if (data2 && data2 != data1) { 2649 sbuf_printf(sb, 2650 "Lock order \"%s\"(%s) -> \"%s\"(%s) first seen at:\n", 2651 tmp_w2->w_name, tmp_w2->w_class->lc_name, 2652 tmp_w1->w_name, tmp_w1->w_class->lc_name); 2653 stack_sbuf_print(sb, &tmp_data2->wlod_stack); 2654 sbuf_printf(sb, "\n"); 2655 } 2656 } 2657 } 2658 mtx_lock_spin(&w_mtx); 2659 if (generation != w_generation) { 2660 mtx_unlock_spin(&w_mtx); 2661 2662 /* 2663 * The graph changed while we were printing stack data, 2664 * try again. 2665 */ 2666 req->oldidx = 0; 2667 sbuf_clear(sb); 2668 goto restart; 2669 } 2670 mtx_unlock_spin(&w_mtx); 2671 2672 /* Free temporary storage space. */ 2673 free(tmp_data1, M_TEMP); 2674 free(tmp_data2, M_TEMP); 2675 free(tmp_w1, M_TEMP); 2676 free(tmp_w2, M_TEMP); 2677 2678 sbuf_finish(sb); 2679 error = SYSCTL_OUT(req, sbuf_data(sb), sbuf_len(sb) + 1); 2680 sbuf_delete(sb); 2681 2682 return (error); 2683 } 2684 2685 static int 2686 sysctl_debug_witness_channel(SYSCTL_HANDLER_ARGS) 2687 { 2688 static const struct { 2689 enum witness_channel channel; 2690 const char *name; 2691 } channels[] = { 2692 { WITNESS_CONSOLE, "console" }, 2693 { WITNESS_LOG, "log" }, 2694 { WITNESS_NONE, "none" }, 2695 }; 2696 char buf[16]; 2697 u_int i; 2698 int error; 2699 2700 buf[0] = '\0'; 2701 for (i = 0; i < nitems(channels); i++) 2702 if (witness_channel == channels[i].channel) { 2703 snprintf(buf, sizeof(buf), "%s", channels[i].name); 2704 break; 2705 } 2706 2707 error = sysctl_handle_string(oidp, buf, sizeof(buf), req); 2708 if (error != 0 || req->newptr == NULL) 2709 return (error); 2710 2711 error = EINVAL; 2712 for (i = 0; i < nitems(channels); i++) 2713 if (strcmp(channels[i].name, buf) == 0) { 2714 witness_channel = channels[i].channel; 2715 error = 0; 2716 break; 2717 } 2718 return (error); 2719 } 2720 2721 static int 2722 sysctl_debug_witness_fullgraph(SYSCTL_HANDLER_ARGS) 2723 { 2724 struct witness *w; 2725 struct sbuf *sb; 2726 int error; 2727 2728 if (witness_watch < 1) { 2729 error = SYSCTL_OUT(req, w_notrunning, sizeof(w_notrunning)); 2730 return (error); 2731 } 2732 if (witness_cold) { 2733 error = SYSCTL_OUT(req, w_stillcold, sizeof(w_stillcold)); 2734 return (error); 2735 } 2736 error = 0; 2737 2738 error = sysctl_wire_old_buffer(req, 0); 2739 if (error != 0) 2740 return (error); 2741 sb = sbuf_new_for_sysctl(NULL, NULL, FULLGRAPH_SBUF_SIZE, req); 2742 if (sb == NULL) 2743 return (ENOMEM); 2744 sbuf_printf(sb, "\n"); 2745 2746 mtx_lock_spin(&w_mtx); 2747 STAILQ_FOREACH(w, &w_all, w_list) 2748 w->w_displayed = 0; 2749 STAILQ_FOREACH(w, &w_all, w_list) 2750 witness_add_fullgraph(sb, w); 2751 mtx_unlock_spin(&w_mtx); 2752 2753 /* 2754 * Close the sbuf and return to userland. 2755 */ 2756 error = sbuf_finish(sb); 2757 sbuf_delete(sb); 2758 2759 return (error); 2760 } 2761 2762 static int 2763 sysctl_debug_witness_watch(SYSCTL_HANDLER_ARGS) 2764 { 2765 int error, value; 2766 2767 value = witness_watch; 2768 error = sysctl_handle_int(oidp, &value, 0, req); 2769 if (error != 0 || req->newptr == NULL) 2770 return (error); 2771 if (value > 1 || value < -1 || 2772 (witness_watch == -1 && value != witness_watch)) 2773 return (EINVAL); 2774 witness_watch = value; 2775 return (0); 2776 } 2777 2778 static void 2779 witness_add_fullgraph(struct sbuf *sb, struct witness *w) 2780 { 2781 int i; 2782 2783 if (w->w_displayed != 0 || (w->w_file == NULL && w->w_line == 0)) 2784 return; 2785 w->w_displayed = 1; 2786 2787 WITNESS_INDEX_ASSERT(w->w_index); 2788 for (i = 1; i <= w_max_used_index; i++) { 2789 if (w_rmatrix[w->w_index][i] & WITNESS_PARENT) { 2790 sbuf_printf(sb, "\"%s\",\"%s\"\n", w->w_name, 2791 w_data[i].w_name); 2792 witness_add_fullgraph(sb, &w_data[i]); 2793 } 2794 } 2795 } 2796 2797 /* 2798 * A simple hash function. Takes a key pointer and a key size. If size == 0, 2799 * interprets the key as a string and reads until the null 2800 * terminator. Otherwise, reads the first size bytes. Returns an unsigned 32-bit 2801 * hash value computed from the key. 2802 */ 2803 static uint32_t 2804 witness_hash_djb2(const uint8_t *key, uint32_t size) 2805 { 2806 unsigned int hash = 5381; 2807 int i; 2808 2809 /* hash = hash * 33 + key[i] */ 2810 if (size) 2811 for (i = 0; i < size; i++) 2812 hash = ((hash << 5) + hash) + (unsigned int)key[i]; 2813 else 2814 for (i = 0; key[i] != 0; i++) 2815 hash = ((hash << 5) + hash) + (unsigned int)key[i]; 2816 2817 return (hash); 2818 } 2819 2820 2821 /* 2822 * Initializes the two witness hash tables. Called exactly once from 2823 * witness_initialize(). 2824 */ 2825 static void 2826 witness_init_hash_tables(void) 2827 { 2828 int i; 2829 2830 MPASS(witness_cold); 2831 2832 /* Initialize the hash tables. */ 2833 for (i = 0; i < WITNESS_HASH_SIZE; i++) 2834 w_hash.wh_array[i] = NULL; 2835 2836 w_hash.wh_size = WITNESS_HASH_SIZE; 2837 w_hash.wh_count = 0; 2838 2839 /* Initialize the lock order data hash. */ 2840 w_lofree = NULL; 2841 for (i = 0; i < WITNESS_LO_DATA_COUNT; i++) { 2842 memset(&w_lodata[i], 0, sizeof(w_lodata[i])); 2843 w_lodata[i].wlod_next = w_lofree; 2844 w_lofree = &w_lodata[i]; 2845 } 2846 w_lohash.wloh_size = WITNESS_LO_HASH_SIZE; 2847 w_lohash.wloh_count = 0; 2848 for (i = 0; i < WITNESS_LO_HASH_SIZE; i++) 2849 w_lohash.wloh_array[i] = NULL; 2850 } 2851 2852 static struct witness * 2853 witness_hash_get(const char *key) 2854 { 2855 struct witness *w; 2856 uint32_t hash; 2857 2858 MPASS(key != NULL); 2859 if (witness_cold == 0) 2860 mtx_assert(&w_mtx, MA_OWNED); 2861 hash = witness_hash_djb2(key, 0) % w_hash.wh_size; 2862 w = w_hash.wh_array[hash]; 2863 while (w != NULL) { 2864 if (strcmp(w->w_name, key) == 0) 2865 goto out; 2866 w = w->w_hash_next; 2867 } 2868 2869 out: 2870 return (w); 2871 } 2872 2873 static void 2874 witness_hash_put(struct witness *w) 2875 { 2876 uint32_t hash; 2877 2878 MPASS(w != NULL); 2879 MPASS(w->w_name != NULL); 2880 if (witness_cold == 0) 2881 mtx_assert(&w_mtx, MA_OWNED); 2882 KASSERT(witness_hash_get(w->w_name) == NULL, 2883 ("%s: trying to add a hash entry that already exists!", __func__)); 2884 KASSERT(w->w_hash_next == NULL, 2885 ("%s: w->w_hash_next != NULL", __func__)); 2886 2887 hash = witness_hash_djb2(w->w_name, 0) % w_hash.wh_size; 2888 w->w_hash_next = w_hash.wh_array[hash]; 2889 w_hash.wh_array[hash] = w; 2890 w_hash.wh_count++; 2891 } 2892 2893 2894 static struct witness_lock_order_data * 2895 witness_lock_order_get(struct witness *parent, struct witness *child) 2896 { 2897 struct witness_lock_order_data *data = NULL; 2898 struct witness_lock_order_key key; 2899 unsigned int hash; 2900 2901 MPASS(parent != NULL && child != NULL); 2902 key.from = parent->w_index; 2903 key.to = child->w_index; 2904 WITNESS_INDEX_ASSERT(key.from); 2905 WITNESS_INDEX_ASSERT(key.to); 2906 if ((w_rmatrix[parent->w_index][child->w_index] 2907 & WITNESS_LOCK_ORDER_KNOWN) == 0) 2908 goto out; 2909 2910 hash = witness_hash_djb2((const char*)&key, 2911 sizeof(key)) % w_lohash.wloh_size; 2912 data = w_lohash.wloh_array[hash]; 2913 while (data != NULL) { 2914 if (witness_lock_order_key_equal(&data->wlod_key, &key)) 2915 break; 2916 data = data->wlod_next; 2917 } 2918 2919 out: 2920 return (data); 2921 } 2922 2923 /* 2924 * Verify that parent and child have a known relationship, are not the same, 2925 * and child is actually a child of parent. This is done without w_mtx 2926 * to avoid contention in the common case. 2927 */ 2928 static int 2929 witness_lock_order_check(struct witness *parent, struct witness *child) 2930 { 2931 2932 if (parent != child && 2933 w_rmatrix[parent->w_index][child->w_index] 2934 & WITNESS_LOCK_ORDER_KNOWN && 2935 isitmychild(parent, child)) 2936 return (1); 2937 2938 return (0); 2939 } 2940 2941 static int 2942 witness_lock_order_add(struct witness *parent, struct witness *child) 2943 { 2944 struct witness_lock_order_data *data = NULL; 2945 struct witness_lock_order_key key; 2946 unsigned int hash; 2947 2948 MPASS(parent != NULL && child != NULL); 2949 key.from = parent->w_index; 2950 key.to = child->w_index; 2951 WITNESS_INDEX_ASSERT(key.from); 2952 WITNESS_INDEX_ASSERT(key.to); 2953 if (w_rmatrix[parent->w_index][child->w_index] 2954 & WITNESS_LOCK_ORDER_KNOWN) 2955 return (1); 2956 2957 hash = witness_hash_djb2((const char*)&key, 2958 sizeof(key)) % w_lohash.wloh_size; 2959 w_rmatrix[parent->w_index][child->w_index] |= WITNESS_LOCK_ORDER_KNOWN; 2960 data = w_lofree; 2961 if (data == NULL) 2962 return (0); 2963 w_lofree = data->wlod_next; 2964 data->wlod_next = w_lohash.wloh_array[hash]; 2965 data->wlod_key = key; 2966 w_lohash.wloh_array[hash] = data; 2967 w_lohash.wloh_count++; 2968 stack_zero(&data->wlod_stack); 2969 stack_save(&data->wlod_stack); 2970 return (1); 2971 } 2972 2973 /* Call this whenever the structure of the witness graph changes. */ 2974 static void 2975 witness_increment_graph_generation(void) 2976 { 2977 2978 if (witness_cold == 0) 2979 mtx_assert(&w_mtx, MA_OWNED); 2980 w_generation++; 2981 } 2982 2983 static int 2984 witness_output_drain(void *arg __unused, const char *data, int len) 2985 { 2986 2987 witness_output("%.*s", len, data); 2988 return (len); 2989 } 2990 2991 static void 2992 witness_debugger(int cond, const char *msg) 2993 { 2994 char buf[32]; 2995 struct sbuf sb; 2996 struct stack st; 2997 2998 if (!cond) 2999 return; 3000 3001 if (witness_trace) { 3002 sbuf_new(&sb, buf, sizeof(buf), SBUF_FIXEDLEN); 3003 sbuf_set_drain(&sb, witness_output_drain, NULL); 3004 3005 stack_zero(&st); 3006 stack_save(&st); 3007 witness_output("stack backtrace:\n"); 3008 stack_sbuf_print_ddb(&sb, &st); 3009 3010 sbuf_finish(&sb); 3011 } 3012 3013 #ifdef KDB 3014 if (witness_kdb) 3015 kdb_enter(KDB_WHY_WITNESS, msg); 3016 #endif 3017 } 3018