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 { "scrlock", &lock_class_mtx_spin }, 641 #ifdef __i386__ 642 { "cy", &lock_class_mtx_spin }, 643 #endif 644 #ifdef __sparc64__ 645 { "pcib_mtx", &lock_class_mtx_spin }, 646 { "rtc_mtx", &lock_class_mtx_spin }, 647 #endif 648 { "scc_hwmtx", &lock_class_mtx_spin }, 649 { "uart_hwmtx", &lock_class_mtx_spin }, 650 { "fast_taskqueue", &lock_class_mtx_spin }, 651 { "intr table", &lock_class_mtx_spin }, 652 #ifdef HWPMC_HOOKS 653 { "pmc-per-proc", &lock_class_mtx_spin }, 654 #endif 655 { "process slock", &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 { "syscons video lock", &lock_class_mtx_spin }, 665 #ifdef SMP 666 { "smp rendezvous", &lock_class_mtx_spin }, 667 #endif 668 #ifdef __powerpc__ 669 { "tlb0", &lock_class_mtx_spin }, 670 #endif 671 /* 672 * leaf locks 673 */ 674 { "intrcnt", &lock_class_mtx_spin }, 675 { "icu", &lock_class_mtx_spin }, 676 #if defined(SMP) && defined(__sparc64__) 677 { "ipi", &lock_class_mtx_spin }, 678 #endif 679 #ifdef __i386__ 680 { "allpmaps", &lock_class_mtx_spin }, 681 { "descriptor tables", &lock_class_mtx_spin }, 682 #endif 683 { "clk", &lock_class_mtx_spin }, 684 { "cpuset", &lock_class_mtx_spin }, 685 { "mprof lock", &lock_class_mtx_spin }, 686 { "zombie lock", &lock_class_mtx_spin }, 687 { "ALD Queue", &lock_class_mtx_spin }, 688 #if defined(__i386__) || defined(__amd64__) 689 { "pcicfg", &lock_class_mtx_spin }, 690 { "NDIS thread lock", &lock_class_mtx_spin }, 691 #endif 692 { "tw_osl_io_lock", &lock_class_mtx_spin }, 693 { "tw_osl_q_lock", &lock_class_mtx_spin }, 694 { "tw_cl_io_lock", &lock_class_mtx_spin }, 695 { "tw_cl_intr_lock", &lock_class_mtx_spin }, 696 { "tw_cl_gen_lock", &lock_class_mtx_spin }, 697 #ifdef HWPMC_HOOKS 698 { "pmc-leaf", &lock_class_mtx_spin }, 699 #endif 700 { "blocked lock", &lock_class_mtx_spin }, 701 { NULL, NULL }, 702 { NULL, NULL } 703 }; 704 705 #ifdef BLESSING 706 /* 707 * Pairs of locks which have been blessed 708 * Don't complain about order problems with blessed locks 709 */ 710 static struct witness_blessed blessed_list[] = { 711 }; 712 static int blessed_count = 713 sizeof(blessed_list) / sizeof(struct witness_blessed); 714 #endif 715 716 /* 717 * This global is set to 0 once it becomes safe to use the witness code. 718 */ 719 static int witness_cold = 1; 720 721 /* 722 * This global is set to 1 once the static lock orders have been enrolled 723 * so that a warning can be issued for any spin locks enrolled later. 724 */ 725 static int witness_spin_warn = 0; 726 727 /* Trim useless garbage from filenames. */ 728 static const char * 729 fixup_filename(const char *file) 730 { 731 732 if (file == NULL) 733 return (NULL); 734 while (strncmp(file, "../", 3) == 0) 735 file += 3; 736 return (file); 737 } 738 739 /* 740 * The WITNESS-enabled diagnostic code. Note that the witness code does 741 * assume that the early boot is single-threaded at least until after this 742 * routine is completed. 743 */ 744 static void 745 witness_initialize(void *dummy __unused) 746 { 747 struct lock_object *lock; 748 struct witness_order_list_entry *order; 749 struct witness *w, *w1; 750 int i; 751 752 w_data = malloc(sizeof (struct witness) * witness_count, M_WITNESS, 753 M_WAITOK | M_ZERO); 754 755 w_rmatrix = malloc(sizeof(*w_rmatrix) * (witness_count + 1), 756 M_WITNESS, M_WAITOK | M_ZERO); 757 758 for (i = 0; i < witness_count + 1; i++) { 759 w_rmatrix[i] = malloc(sizeof(*w_rmatrix[i]) * 760 (witness_count + 1), M_WITNESS, M_WAITOK | M_ZERO); 761 } 762 badstack_sbuf_size = witness_count * 256; 763 764 /* 765 * We have to release Giant before initializing its witness 766 * structure so that WITNESS doesn't get confused. 767 */ 768 mtx_unlock(&Giant); 769 mtx_assert(&Giant, MA_NOTOWNED); 770 771 CTR1(KTR_WITNESS, "%s: initializing witness", __func__); 772 mtx_init(&w_mtx, "witness lock", NULL, MTX_SPIN | MTX_QUIET | 773 MTX_NOWITNESS | MTX_NOPROFILE); 774 for (i = witness_count - 1; i >= 0; i--) { 775 w = &w_data[i]; 776 memset(w, 0, sizeof(*w)); 777 w_data[i].w_index = i; /* Witness index never changes. */ 778 witness_free(w); 779 } 780 KASSERT(STAILQ_FIRST(&w_free)->w_index == 0, 781 ("%s: Invalid list of free witness objects", __func__)); 782 783 /* Witness with index 0 is not used to aid in debugging. */ 784 STAILQ_REMOVE_HEAD(&w_free, w_list); 785 w_free_cnt--; 786 787 for (i = 0; i < witness_count; i++) { 788 memset(w_rmatrix[i], 0, sizeof(*w_rmatrix[i]) * 789 (witness_count + 1)); 790 } 791 792 for (i = 0; i < LOCK_CHILDCOUNT; i++) 793 witness_lock_list_free(&w_locklistdata[i]); 794 witness_init_hash_tables(); 795 796 /* First add in all the specified order lists. */ 797 for (order = order_lists; order->w_name != NULL; order++) { 798 w = enroll(order->w_name, order->w_class); 799 if (w == NULL) 800 continue; 801 w->w_file = "order list"; 802 for (order++; order->w_name != NULL; order++) { 803 w1 = enroll(order->w_name, order->w_class); 804 if (w1 == NULL) 805 continue; 806 w1->w_file = "order list"; 807 itismychild(w, w1); 808 w = w1; 809 } 810 } 811 witness_spin_warn = 1; 812 813 /* Iterate through all locks and add them to witness. */ 814 for (i = 0; pending_locks[i].wh_lock != NULL; i++) { 815 lock = pending_locks[i].wh_lock; 816 KASSERT(lock->lo_flags & LO_WITNESS, 817 ("%s: lock %s is on pending list but not LO_WITNESS", 818 __func__, lock->lo_name)); 819 lock->lo_witness = enroll(pending_locks[i].wh_type, 820 LOCK_CLASS(lock)); 821 } 822 823 /* Mark the witness code as being ready for use. */ 824 witness_cold = 0; 825 826 mtx_lock(&Giant); 827 } 828 SYSINIT(witness_init, SI_SUB_WITNESS, SI_ORDER_FIRST, witness_initialize, 829 NULL); 830 831 void 832 witness_init(struct lock_object *lock, const char *type) 833 { 834 struct lock_class *class; 835 836 /* Various sanity checks. */ 837 class = LOCK_CLASS(lock); 838 if ((lock->lo_flags & LO_RECURSABLE) != 0 && 839 (class->lc_flags & LC_RECURSABLE) == 0) 840 kassert_panic("%s: lock (%s) %s can not be recursable", 841 __func__, class->lc_name, lock->lo_name); 842 if ((lock->lo_flags & LO_SLEEPABLE) != 0 && 843 (class->lc_flags & LC_SLEEPABLE) == 0) 844 kassert_panic("%s: lock (%s) %s can not be sleepable", 845 __func__, class->lc_name, lock->lo_name); 846 if ((lock->lo_flags & LO_UPGRADABLE) != 0 && 847 (class->lc_flags & LC_UPGRADABLE) == 0) 848 kassert_panic("%s: lock (%s) %s can not be upgradable", 849 __func__, class->lc_name, lock->lo_name); 850 851 /* 852 * If we shouldn't watch this lock, then just clear lo_witness. 853 * Otherwise, if witness_cold is set, then it is too early to 854 * enroll this lock, so defer it to witness_initialize() by adding 855 * it to the pending_locks list. If it is not too early, then enroll 856 * the lock now. 857 */ 858 if (witness_watch < 1 || panicstr != NULL || 859 (lock->lo_flags & LO_WITNESS) == 0) 860 lock->lo_witness = NULL; 861 else if (witness_cold) { 862 pending_locks[pending_cnt].wh_lock = lock; 863 pending_locks[pending_cnt++].wh_type = type; 864 if (pending_cnt > WITNESS_PENDLIST) 865 panic("%s: pending locks list is too small, " 866 "increase WITNESS_PENDLIST\n", 867 __func__); 868 } else 869 lock->lo_witness = enroll(type, class); 870 } 871 872 void 873 witness_destroy(struct lock_object *lock) 874 { 875 struct lock_class *class; 876 struct witness *w; 877 878 class = LOCK_CLASS(lock); 879 880 if (witness_cold) 881 panic("lock (%s) %s destroyed while witness_cold", 882 class->lc_name, lock->lo_name); 883 884 /* XXX: need to verify that no one holds the lock */ 885 if ((lock->lo_flags & LO_WITNESS) == 0 || lock->lo_witness == NULL) 886 return; 887 w = lock->lo_witness; 888 889 mtx_lock_spin(&w_mtx); 890 MPASS(w->w_refcount > 0); 891 w->w_refcount--; 892 893 if (w->w_refcount == 0) 894 depart(w); 895 mtx_unlock_spin(&w_mtx); 896 } 897 898 #ifdef DDB 899 static void 900 witness_ddb_compute_levels(void) 901 { 902 struct witness *w; 903 904 /* 905 * First clear all levels. 906 */ 907 STAILQ_FOREACH(w, &w_all, w_list) 908 w->w_ddb_level = -1; 909 910 /* 911 * Look for locks with no parents and level all their descendants. 912 */ 913 STAILQ_FOREACH(w, &w_all, w_list) { 914 915 /* If the witness has ancestors (is not a root), skip it. */ 916 if (w->w_num_ancestors > 0) 917 continue; 918 witness_ddb_level_descendants(w, 0); 919 } 920 } 921 922 static void 923 witness_ddb_level_descendants(struct witness *w, int l) 924 { 925 int i; 926 927 if (w->w_ddb_level >= l) 928 return; 929 930 w->w_ddb_level = l; 931 l++; 932 933 for (i = 1; i <= w_max_used_index; i++) { 934 if (w_rmatrix[w->w_index][i] & WITNESS_PARENT) 935 witness_ddb_level_descendants(&w_data[i], l); 936 } 937 } 938 939 static void 940 witness_ddb_display_descendants(int(*prnt)(const char *fmt, ...), 941 struct witness *w, int indent) 942 { 943 int i; 944 945 for (i = 0; i < indent; i++) 946 prnt(" "); 947 prnt("%s (type: %s, depth: %d, active refs: %d)", 948 w->w_name, w->w_class->lc_name, 949 w->w_ddb_level, w->w_refcount); 950 if (w->w_displayed) { 951 prnt(" -- (already displayed)\n"); 952 return; 953 } 954 w->w_displayed = 1; 955 if (w->w_file != NULL && w->w_line != 0) 956 prnt(" -- last acquired @ %s:%d\n", fixup_filename(w->w_file), 957 w->w_line); 958 else 959 prnt(" -- never acquired\n"); 960 indent++; 961 WITNESS_INDEX_ASSERT(w->w_index); 962 for (i = 1; i <= w_max_used_index; i++) { 963 if (db_pager_quit) 964 return; 965 if (w_rmatrix[w->w_index][i] & WITNESS_PARENT) 966 witness_ddb_display_descendants(prnt, &w_data[i], 967 indent); 968 } 969 } 970 971 static void 972 witness_ddb_display_list(int(*prnt)(const char *fmt, ...), 973 struct witness_list *list) 974 { 975 struct witness *w; 976 977 STAILQ_FOREACH(w, list, w_typelist) { 978 if (w->w_file == NULL || w->w_ddb_level > 0) 979 continue; 980 981 /* This lock has no anscestors - display its descendants. */ 982 witness_ddb_display_descendants(prnt, w, 0); 983 if (db_pager_quit) 984 return; 985 } 986 } 987 988 static void 989 witness_ddb_display(int(*prnt)(const char *fmt, ...)) 990 { 991 struct witness *w; 992 993 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); 994 witness_ddb_compute_levels(); 995 996 /* Clear all the displayed flags. */ 997 STAILQ_FOREACH(w, &w_all, w_list) 998 w->w_displayed = 0; 999 1000 /* 1001 * First, handle sleep locks which have been acquired at least 1002 * once. 1003 */ 1004 prnt("Sleep locks:\n"); 1005 witness_ddb_display_list(prnt, &w_sleep); 1006 if (db_pager_quit) 1007 return; 1008 1009 /* 1010 * Now do spin locks which have been acquired at least once. 1011 */ 1012 prnt("\nSpin locks:\n"); 1013 witness_ddb_display_list(prnt, &w_spin); 1014 if (db_pager_quit) 1015 return; 1016 1017 /* 1018 * Finally, any locks which have not been acquired yet. 1019 */ 1020 prnt("\nLocks which were never acquired:\n"); 1021 STAILQ_FOREACH(w, &w_all, w_list) { 1022 if (w->w_file != NULL || w->w_refcount == 0) 1023 continue; 1024 prnt("%s (type: %s, depth: %d)\n", w->w_name, 1025 w->w_class->lc_name, w->w_ddb_level); 1026 if (db_pager_quit) 1027 return; 1028 } 1029 } 1030 #endif /* DDB */ 1031 1032 int 1033 witness_defineorder(struct lock_object *lock1, struct lock_object *lock2) 1034 { 1035 1036 if (witness_watch == -1 || panicstr != NULL) 1037 return (0); 1038 1039 /* Require locks that witness knows about. */ 1040 if (lock1 == NULL || lock1->lo_witness == NULL || lock2 == NULL || 1041 lock2->lo_witness == NULL) 1042 return (EINVAL); 1043 1044 mtx_assert(&w_mtx, MA_NOTOWNED); 1045 mtx_lock_spin(&w_mtx); 1046 1047 /* 1048 * If we already have either an explicit or implied lock order that 1049 * is the other way around, then return an error. 1050 */ 1051 if (witness_watch && 1052 isitmydescendant(lock2->lo_witness, lock1->lo_witness)) { 1053 mtx_unlock_spin(&w_mtx); 1054 return (EDOOFUS); 1055 } 1056 1057 /* Try to add the new order. */ 1058 CTR3(KTR_WITNESS, "%s: adding %s as a child of %s", __func__, 1059 lock2->lo_witness->w_name, lock1->lo_witness->w_name); 1060 itismychild(lock1->lo_witness, lock2->lo_witness); 1061 mtx_unlock_spin(&w_mtx); 1062 return (0); 1063 } 1064 1065 void 1066 witness_checkorder(struct lock_object *lock, int flags, const char *file, 1067 int line, struct lock_object *interlock) 1068 { 1069 struct lock_list_entry *lock_list, *lle; 1070 struct lock_instance *lock1, *lock2, *plock; 1071 struct lock_class *class, *iclass; 1072 struct witness *w, *w1; 1073 struct thread *td; 1074 int i, j; 1075 1076 if (witness_cold || witness_watch < 1 || lock->lo_witness == NULL || 1077 panicstr != NULL) 1078 return; 1079 1080 w = lock->lo_witness; 1081 class = LOCK_CLASS(lock); 1082 td = curthread; 1083 1084 if (class->lc_flags & LC_SLEEPLOCK) { 1085 1086 /* 1087 * Since spin locks include a critical section, this check 1088 * implicitly enforces a lock order of all sleep locks before 1089 * all spin locks. 1090 */ 1091 if (td->td_critnest != 0 && !kdb_active) 1092 kassert_panic("acquiring blockable sleep lock with " 1093 "spinlock or critical section held (%s) %s @ %s:%d", 1094 class->lc_name, lock->lo_name, 1095 fixup_filename(file), line); 1096 1097 /* 1098 * If this is the first lock acquired then just return as 1099 * no order checking is needed. 1100 */ 1101 lock_list = td->td_sleeplocks; 1102 if (lock_list == NULL || lock_list->ll_count == 0) 1103 return; 1104 } else { 1105 1106 /* 1107 * If this is the first lock, just return as no order 1108 * checking is needed. Avoid problems with thread 1109 * migration pinning the thread while checking if 1110 * spinlocks are held. If at least one spinlock is held 1111 * the thread is in a safe path and it is allowed to 1112 * unpin it. 1113 */ 1114 sched_pin(); 1115 lock_list = PCPU_GET(spinlocks); 1116 if (lock_list == NULL || lock_list->ll_count == 0) { 1117 sched_unpin(); 1118 return; 1119 } 1120 sched_unpin(); 1121 } 1122 1123 /* 1124 * Check to see if we are recursing on a lock we already own. If 1125 * so, make sure that we don't mismatch exclusive and shared lock 1126 * acquires. 1127 */ 1128 lock1 = find_instance(lock_list, lock); 1129 if (lock1 != NULL) { 1130 if ((lock1->li_flags & LI_EXCLUSIVE) != 0 && 1131 (flags & LOP_EXCLUSIVE) == 0) { 1132 witness_output("shared lock of (%s) %s @ %s:%d\n", 1133 class->lc_name, lock->lo_name, 1134 fixup_filename(file), line); 1135 witness_output("while exclusively locked from %s:%d\n", 1136 fixup_filename(lock1->li_file), lock1->li_line); 1137 kassert_panic("excl->share"); 1138 } 1139 if ((lock1->li_flags & LI_EXCLUSIVE) == 0 && 1140 (flags & LOP_EXCLUSIVE) != 0) { 1141 witness_output("exclusive lock of (%s) %s @ %s:%d\n", 1142 class->lc_name, lock->lo_name, 1143 fixup_filename(file), line); 1144 witness_output("while share locked from %s:%d\n", 1145 fixup_filename(lock1->li_file), lock1->li_line); 1146 kassert_panic("share->excl"); 1147 } 1148 return; 1149 } 1150 1151 /* Warn if the interlock is not locked exactly once. */ 1152 if (interlock != NULL) { 1153 iclass = LOCK_CLASS(interlock); 1154 lock1 = find_instance(lock_list, interlock); 1155 if (lock1 == NULL) 1156 kassert_panic("interlock (%s) %s not locked @ %s:%d", 1157 iclass->lc_name, interlock->lo_name, 1158 fixup_filename(file), line); 1159 else if ((lock1->li_flags & LI_RECURSEMASK) != 0) 1160 kassert_panic("interlock (%s) %s recursed @ %s:%d", 1161 iclass->lc_name, interlock->lo_name, 1162 fixup_filename(file), line); 1163 } 1164 1165 /* 1166 * Find the previously acquired lock, but ignore interlocks. 1167 */ 1168 plock = &lock_list->ll_children[lock_list->ll_count - 1]; 1169 if (interlock != NULL && plock->li_lock == interlock) { 1170 if (lock_list->ll_count > 1) 1171 plock = 1172 &lock_list->ll_children[lock_list->ll_count - 2]; 1173 else { 1174 lle = lock_list->ll_next; 1175 1176 /* 1177 * The interlock is the only lock we hold, so 1178 * simply return. 1179 */ 1180 if (lle == NULL) 1181 return; 1182 plock = &lle->ll_children[lle->ll_count - 1]; 1183 } 1184 } 1185 1186 /* 1187 * Try to perform most checks without a lock. If this succeeds we 1188 * can skip acquiring the lock and return success. Otherwise we redo 1189 * the check with the lock held to handle races with concurrent updates. 1190 */ 1191 w1 = plock->li_lock->lo_witness; 1192 if (witness_lock_order_check(w1, w)) 1193 return; 1194 1195 mtx_lock_spin(&w_mtx); 1196 if (witness_lock_order_check(w1, w)) { 1197 mtx_unlock_spin(&w_mtx); 1198 return; 1199 } 1200 witness_lock_order_add(w1, w); 1201 1202 /* 1203 * Check for duplicate locks of the same type. Note that we only 1204 * have to check for this on the last lock we just acquired. Any 1205 * other cases will be caught as lock order violations. 1206 */ 1207 if (w1 == w) { 1208 i = w->w_index; 1209 if (!(lock->lo_flags & LO_DUPOK) && !(flags & LOP_DUPOK) && 1210 !(w_rmatrix[i][i] & WITNESS_REVERSAL)) { 1211 w_rmatrix[i][i] |= WITNESS_REVERSAL; 1212 w->w_reversed = 1; 1213 mtx_unlock_spin(&w_mtx); 1214 witness_output( 1215 "acquiring duplicate lock of same type: \"%s\"\n", 1216 w->w_name); 1217 witness_output(" 1st %s @ %s:%d\n", plock->li_lock->lo_name, 1218 fixup_filename(plock->li_file), plock->li_line); 1219 witness_output(" 2nd %s @ %s:%d\n", lock->lo_name, 1220 fixup_filename(file), line); 1221 witness_debugger(1, __func__); 1222 } else 1223 mtx_unlock_spin(&w_mtx); 1224 return; 1225 } 1226 mtx_assert(&w_mtx, MA_OWNED); 1227 1228 /* 1229 * If we know that the lock we are acquiring comes after 1230 * the lock we most recently acquired in the lock order tree, 1231 * then there is no need for any further checks. 1232 */ 1233 if (isitmychild(w1, w)) 1234 goto out; 1235 1236 for (j = 0, lle = lock_list; lle != NULL; lle = lle->ll_next) { 1237 for (i = lle->ll_count - 1; i >= 0; i--, j++) { 1238 1239 MPASS(j < LOCK_CHILDCOUNT * LOCK_NCHILDREN); 1240 lock1 = &lle->ll_children[i]; 1241 1242 /* 1243 * Ignore the interlock. 1244 */ 1245 if (interlock == lock1->li_lock) 1246 continue; 1247 1248 /* 1249 * If this lock doesn't undergo witness checking, 1250 * then skip it. 1251 */ 1252 w1 = lock1->li_lock->lo_witness; 1253 if (w1 == NULL) { 1254 KASSERT((lock1->li_lock->lo_flags & LO_WITNESS) == 0, 1255 ("lock missing witness structure")); 1256 continue; 1257 } 1258 1259 /* 1260 * If we are locking Giant and this is a sleepable 1261 * lock, then skip it. 1262 */ 1263 if ((lock1->li_lock->lo_flags & LO_SLEEPABLE) != 0 && 1264 lock == &Giant.lock_object) 1265 continue; 1266 1267 /* 1268 * If we are locking a sleepable lock and this lock 1269 * is Giant, then skip it. 1270 */ 1271 if ((lock->lo_flags & LO_SLEEPABLE) != 0 && 1272 lock1->li_lock == &Giant.lock_object) 1273 continue; 1274 1275 /* 1276 * If we are locking a sleepable lock and this lock 1277 * isn't sleepable, we want to treat it as a lock 1278 * order violation to enfore a general lock order of 1279 * sleepable locks before non-sleepable locks. 1280 */ 1281 if (((lock->lo_flags & LO_SLEEPABLE) != 0 && 1282 (lock1->li_lock->lo_flags & LO_SLEEPABLE) == 0)) 1283 goto reversal; 1284 1285 /* 1286 * If we are locking Giant and this is a non-sleepable 1287 * lock, then treat it as a reversal. 1288 */ 1289 if ((lock1->li_lock->lo_flags & LO_SLEEPABLE) == 0 && 1290 lock == &Giant.lock_object) 1291 goto reversal; 1292 1293 /* 1294 * Check the lock order hierarchy for a reveresal. 1295 */ 1296 if (!isitmydescendant(w, w1)) 1297 continue; 1298 reversal: 1299 1300 /* 1301 * We have a lock order violation, check to see if it 1302 * is allowed or has already been yelled about. 1303 */ 1304 #ifdef BLESSING 1305 1306 /* 1307 * If the lock order is blessed, just bail. We don't 1308 * look for other lock order violations though, which 1309 * may be a bug. 1310 */ 1311 if (blessed(w, w1)) 1312 goto out; 1313 #endif 1314 1315 /* Bail if this violation is known */ 1316 if (w_rmatrix[w1->w_index][w->w_index] & WITNESS_REVERSAL) 1317 goto out; 1318 1319 /* Record this as a violation */ 1320 w_rmatrix[w1->w_index][w->w_index] |= WITNESS_REVERSAL; 1321 w_rmatrix[w->w_index][w1->w_index] |= WITNESS_REVERSAL; 1322 w->w_reversed = w1->w_reversed = 1; 1323 witness_increment_graph_generation(); 1324 mtx_unlock_spin(&w_mtx); 1325 1326 #ifdef WITNESS_NO_VNODE 1327 /* 1328 * There are known LORs between VNODE locks. They are 1329 * not an indication of a bug. VNODE locks are flagged 1330 * as such (LO_IS_VNODE) and we don't yell if the LOR 1331 * is between 2 VNODE locks. 1332 */ 1333 if ((lock->lo_flags & LO_IS_VNODE) != 0 && 1334 (lock1->li_lock->lo_flags & LO_IS_VNODE) != 0) 1335 return; 1336 #endif 1337 1338 /* 1339 * Ok, yell about it. 1340 */ 1341 if (((lock->lo_flags & LO_SLEEPABLE) != 0 && 1342 (lock1->li_lock->lo_flags & LO_SLEEPABLE) == 0)) 1343 witness_output( 1344 "lock order reversal: (sleepable after non-sleepable)\n"); 1345 else if ((lock1->li_lock->lo_flags & LO_SLEEPABLE) == 0 1346 && lock == &Giant.lock_object) 1347 witness_output( 1348 "lock order reversal: (Giant after non-sleepable)\n"); 1349 else 1350 witness_output("lock order reversal:\n"); 1351 1352 /* 1353 * Try to locate an earlier lock with 1354 * witness w in our list. 1355 */ 1356 do { 1357 lock2 = &lle->ll_children[i]; 1358 MPASS(lock2->li_lock != NULL); 1359 if (lock2->li_lock->lo_witness == w) 1360 break; 1361 if (i == 0 && lle->ll_next != NULL) { 1362 lle = lle->ll_next; 1363 i = lle->ll_count - 1; 1364 MPASS(i >= 0 && i < LOCK_NCHILDREN); 1365 } else 1366 i--; 1367 } while (i >= 0); 1368 if (i < 0) { 1369 witness_output(" 1st %p %s (%s) @ %s:%d\n", 1370 lock1->li_lock, lock1->li_lock->lo_name, 1371 w1->w_name, fixup_filename(lock1->li_file), 1372 lock1->li_line); 1373 witness_output(" 2nd %p %s (%s) @ %s:%d\n", lock, 1374 lock->lo_name, w->w_name, 1375 fixup_filename(file), line); 1376 } else { 1377 witness_output(" 1st %p %s (%s) @ %s:%d\n", 1378 lock2->li_lock, lock2->li_lock->lo_name, 1379 lock2->li_lock->lo_witness->w_name, 1380 fixup_filename(lock2->li_file), 1381 lock2->li_line); 1382 witness_output(" 2nd %p %s (%s) @ %s:%d\n", 1383 lock1->li_lock, lock1->li_lock->lo_name, 1384 w1->w_name, fixup_filename(lock1->li_file), 1385 lock1->li_line); 1386 witness_output(" 3rd %p %s (%s) @ %s:%d\n", lock, 1387 lock->lo_name, w->w_name, 1388 fixup_filename(file), line); 1389 } 1390 witness_debugger(1, __func__); 1391 return; 1392 } 1393 } 1394 1395 /* 1396 * If requested, build a new lock order. However, don't build a new 1397 * relationship between a sleepable lock and Giant if it is in the 1398 * wrong direction. The correct lock order is that sleepable locks 1399 * always come before Giant. 1400 */ 1401 if (flags & LOP_NEWORDER && 1402 !(plock->li_lock == &Giant.lock_object && 1403 (lock->lo_flags & LO_SLEEPABLE) != 0)) { 1404 CTR3(KTR_WITNESS, "%s: adding %s as a child of %s", __func__, 1405 w->w_name, plock->li_lock->lo_witness->w_name); 1406 itismychild(plock->li_lock->lo_witness, w); 1407 } 1408 out: 1409 mtx_unlock_spin(&w_mtx); 1410 } 1411 1412 void 1413 witness_lock(struct lock_object *lock, int flags, const char *file, int line) 1414 { 1415 struct lock_list_entry **lock_list, *lle; 1416 struct lock_instance *instance; 1417 struct witness *w; 1418 struct thread *td; 1419 1420 if (witness_cold || witness_watch == -1 || lock->lo_witness == NULL || 1421 panicstr != NULL) 1422 return; 1423 w = lock->lo_witness; 1424 td = curthread; 1425 1426 /* Determine lock list for this lock. */ 1427 if (LOCK_CLASS(lock)->lc_flags & LC_SLEEPLOCK) 1428 lock_list = &td->td_sleeplocks; 1429 else 1430 lock_list = PCPU_PTR(spinlocks); 1431 1432 /* Check to see if we are recursing on a lock we already own. */ 1433 instance = find_instance(*lock_list, lock); 1434 if (instance != NULL) { 1435 instance->li_flags++; 1436 CTR4(KTR_WITNESS, "%s: pid %d recursed on %s r=%d", __func__, 1437 td->td_proc->p_pid, lock->lo_name, 1438 instance->li_flags & LI_RECURSEMASK); 1439 instance->li_file = file; 1440 instance->li_line = line; 1441 return; 1442 } 1443 1444 /* Update per-witness last file and line acquire. */ 1445 w->w_file = file; 1446 w->w_line = line; 1447 1448 /* Find the next open lock instance in the list and fill it. */ 1449 lle = *lock_list; 1450 if (lle == NULL || lle->ll_count == LOCK_NCHILDREN) { 1451 lle = witness_lock_list_get(); 1452 if (lle == NULL) 1453 return; 1454 lle->ll_next = *lock_list; 1455 CTR3(KTR_WITNESS, "%s: pid %d added lle %p", __func__, 1456 td->td_proc->p_pid, lle); 1457 *lock_list = lle; 1458 } 1459 instance = &lle->ll_children[lle->ll_count++]; 1460 instance->li_lock = lock; 1461 instance->li_line = line; 1462 instance->li_file = file; 1463 if ((flags & LOP_EXCLUSIVE) != 0) 1464 instance->li_flags = LI_EXCLUSIVE; 1465 else 1466 instance->li_flags = 0; 1467 CTR4(KTR_WITNESS, "%s: pid %d added %s as lle[%d]", __func__, 1468 td->td_proc->p_pid, lock->lo_name, lle->ll_count - 1); 1469 } 1470 1471 void 1472 witness_upgrade(struct lock_object *lock, int flags, const char *file, int line) 1473 { 1474 struct lock_instance *instance; 1475 struct lock_class *class; 1476 1477 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); 1478 if (lock->lo_witness == NULL || witness_watch == -1 || panicstr != NULL) 1479 return; 1480 class = LOCK_CLASS(lock); 1481 if (witness_watch) { 1482 if ((lock->lo_flags & LO_UPGRADABLE) == 0) 1483 kassert_panic( 1484 "upgrade of non-upgradable lock (%s) %s @ %s:%d", 1485 class->lc_name, lock->lo_name, 1486 fixup_filename(file), line); 1487 if ((class->lc_flags & LC_SLEEPLOCK) == 0) 1488 kassert_panic( 1489 "upgrade of non-sleep lock (%s) %s @ %s:%d", 1490 class->lc_name, lock->lo_name, 1491 fixup_filename(file), line); 1492 } 1493 instance = find_instance(curthread->td_sleeplocks, lock); 1494 if (instance == NULL) { 1495 kassert_panic("upgrade of unlocked lock (%s) %s @ %s:%d", 1496 class->lc_name, lock->lo_name, 1497 fixup_filename(file), line); 1498 return; 1499 } 1500 if (witness_watch) { 1501 if ((instance->li_flags & LI_EXCLUSIVE) != 0) 1502 kassert_panic( 1503 "upgrade of exclusive lock (%s) %s @ %s:%d", 1504 class->lc_name, lock->lo_name, 1505 fixup_filename(file), line); 1506 if ((instance->li_flags & LI_RECURSEMASK) != 0) 1507 kassert_panic( 1508 "upgrade of recursed lock (%s) %s r=%d @ %s:%d", 1509 class->lc_name, lock->lo_name, 1510 instance->li_flags & LI_RECURSEMASK, 1511 fixup_filename(file), line); 1512 } 1513 instance->li_flags |= LI_EXCLUSIVE; 1514 } 1515 1516 void 1517 witness_downgrade(struct lock_object *lock, int flags, const char *file, 1518 int line) 1519 { 1520 struct lock_instance *instance; 1521 struct lock_class *class; 1522 1523 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); 1524 if (lock->lo_witness == NULL || witness_watch == -1 || panicstr != NULL) 1525 return; 1526 class = LOCK_CLASS(lock); 1527 if (witness_watch) { 1528 if ((lock->lo_flags & LO_UPGRADABLE) == 0) 1529 kassert_panic( 1530 "downgrade of non-upgradable lock (%s) %s @ %s:%d", 1531 class->lc_name, lock->lo_name, 1532 fixup_filename(file), line); 1533 if ((class->lc_flags & LC_SLEEPLOCK) == 0) 1534 kassert_panic( 1535 "downgrade of non-sleep lock (%s) %s @ %s:%d", 1536 class->lc_name, lock->lo_name, 1537 fixup_filename(file), line); 1538 } 1539 instance = find_instance(curthread->td_sleeplocks, lock); 1540 if (instance == NULL) { 1541 kassert_panic("downgrade of unlocked lock (%s) %s @ %s:%d", 1542 class->lc_name, lock->lo_name, 1543 fixup_filename(file), line); 1544 return; 1545 } 1546 if (witness_watch) { 1547 if ((instance->li_flags & LI_EXCLUSIVE) == 0) 1548 kassert_panic( 1549 "downgrade of shared lock (%s) %s @ %s:%d", 1550 class->lc_name, lock->lo_name, 1551 fixup_filename(file), line); 1552 if ((instance->li_flags & LI_RECURSEMASK) != 0) 1553 kassert_panic( 1554 "downgrade of recursed lock (%s) %s r=%d @ %s:%d", 1555 class->lc_name, lock->lo_name, 1556 instance->li_flags & LI_RECURSEMASK, 1557 fixup_filename(file), line); 1558 } 1559 instance->li_flags &= ~LI_EXCLUSIVE; 1560 } 1561 1562 void 1563 witness_unlock(struct lock_object *lock, int flags, const char *file, int line) 1564 { 1565 struct lock_list_entry **lock_list, *lle; 1566 struct lock_instance *instance; 1567 struct lock_class *class; 1568 struct thread *td; 1569 register_t s; 1570 int i, j; 1571 1572 if (witness_cold || lock->lo_witness == NULL || panicstr != NULL) 1573 return; 1574 td = curthread; 1575 class = LOCK_CLASS(lock); 1576 1577 /* Find lock instance associated with this lock. */ 1578 if (class->lc_flags & LC_SLEEPLOCK) 1579 lock_list = &td->td_sleeplocks; 1580 else 1581 lock_list = PCPU_PTR(spinlocks); 1582 lle = *lock_list; 1583 for (; *lock_list != NULL; lock_list = &(*lock_list)->ll_next) 1584 for (i = 0; i < (*lock_list)->ll_count; i++) { 1585 instance = &(*lock_list)->ll_children[i]; 1586 if (instance->li_lock == lock) 1587 goto found; 1588 } 1589 1590 /* 1591 * When disabling WITNESS through witness_watch we could end up in 1592 * having registered locks in the td_sleeplocks queue. 1593 * We have to make sure we flush these queues, so just search for 1594 * eventual register locks and remove them. 1595 */ 1596 if (witness_watch > 0) { 1597 kassert_panic("lock (%s) %s not locked @ %s:%d", class->lc_name, 1598 lock->lo_name, fixup_filename(file), line); 1599 return; 1600 } else { 1601 return; 1602 } 1603 found: 1604 1605 /* First, check for shared/exclusive mismatches. */ 1606 if ((instance->li_flags & LI_EXCLUSIVE) != 0 && witness_watch > 0 && 1607 (flags & LOP_EXCLUSIVE) == 0) { 1608 witness_output("shared unlock of (%s) %s @ %s:%d\n", 1609 class->lc_name, lock->lo_name, fixup_filename(file), line); 1610 witness_output("while exclusively locked from %s:%d\n", 1611 fixup_filename(instance->li_file), instance->li_line); 1612 kassert_panic("excl->ushare"); 1613 } 1614 if ((instance->li_flags & LI_EXCLUSIVE) == 0 && witness_watch > 0 && 1615 (flags & LOP_EXCLUSIVE) != 0) { 1616 witness_output("exclusive unlock of (%s) %s @ %s:%d\n", 1617 class->lc_name, lock->lo_name, fixup_filename(file), line); 1618 witness_output("while share locked from %s:%d\n", 1619 fixup_filename(instance->li_file), 1620 instance->li_line); 1621 kassert_panic("share->uexcl"); 1622 } 1623 /* If we are recursed, unrecurse. */ 1624 if ((instance->li_flags & LI_RECURSEMASK) > 0) { 1625 CTR4(KTR_WITNESS, "%s: pid %d unrecursed on %s r=%d", __func__, 1626 td->td_proc->p_pid, instance->li_lock->lo_name, 1627 instance->li_flags); 1628 instance->li_flags--; 1629 return; 1630 } 1631 /* The lock is now being dropped, check for NORELEASE flag */ 1632 if ((instance->li_flags & LI_NORELEASE) != 0 && witness_watch > 0) { 1633 witness_output("forbidden unlock of (%s) %s @ %s:%d\n", 1634 class->lc_name, lock->lo_name, fixup_filename(file), line); 1635 kassert_panic("lock marked norelease"); 1636 } 1637 1638 /* Otherwise, remove this item from the list. */ 1639 s = intr_disable(); 1640 CTR4(KTR_WITNESS, "%s: pid %d removed %s from lle[%d]", __func__, 1641 td->td_proc->p_pid, instance->li_lock->lo_name, 1642 (*lock_list)->ll_count - 1); 1643 for (j = i; j < (*lock_list)->ll_count - 1; j++) 1644 (*lock_list)->ll_children[j] = 1645 (*lock_list)->ll_children[j + 1]; 1646 (*lock_list)->ll_count--; 1647 intr_restore(s); 1648 1649 /* 1650 * In order to reduce contention on w_mtx, we want to keep always an 1651 * head object into lists so that frequent allocation from the 1652 * free witness pool (and subsequent locking) is avoided. 1653 * In order to maintain the current code simple, when the head 1654 * object is totally unloaded it means also that we do not have 1655 * further objects in the list, so the list ownership needs to be 1656 * hand over to another object if the current head needs to be freed. 1657 */ 1658 if ((*lock_list)->ll_count == 0) { 1659 if (*lock_list == lle) { 1660 if (lle->ll_next == NULL) 1661 return; 1662 } else 1663 lle = *lock_list; 1664 *lock_list = lle->ll_next; 1665 CTR3(KTR_WITNESS, "%s: pid %d removed lle %p", __func__, 1666 td->td_proc->p_pid, lle); 1667 witness_lock_list_free(lle); 1668 } 1669 } 1670 1671 void 1672 witness_thread_exit(struct thread *td) 1673 { 1674 struct lock_list_entry *lle; 1675 int i, n; 1676 1677 lle = td->td_sleeplocks; 1678 if (lle == NULL || panicstr != NULL) 1679 return; 1680 if (lle->ll_count != 0) { 1681 for (n = 0; lle != NULL; lle = lle->ll_next) 1682 for (i = lle->ll_count - 1; i >= 0; i--) { 1683 if (n == 0) 1684 witness_output( 1685 "Thread %p exiting with the following locks held:\n", td); 1686 n++; 1687 witness_list_lock(&lle->ll_children[i], 1688 witness_output); 1689 1690 } 1691 kassert_panic( 1692 "Thread %p cannot exit while holding sleeplocks\n", td); 1693 } 1694 witness_lock_list_free(lle); 1695 } 1696 1697 /* 1698 * Warn if any locks other than 'lock' are held. Flags can be passed in to 1699 * exempt Giant and sleepable locks from the checks as well. If any 1700 * non-exempt locks are held, then a supplied message is printed to the 1701 * output channel along with a list of the offending locks. If indicated in the 1702 * flags then a failure results in a panic as well. 1703 */ 1704 int 1705 witness_warn(int flags, struct lock_object *lock, const char *fmt, ...) 1706 { 1707 struct lock_list_entry *lock_list, *lle; 1708 struct lock_instance *lock1; 1709 struct thread *td; 1710 va_list ap; 1711 int i, n; 1712 1713 if (witness_cold || witness_watch < 1 || panicstr != NULL) 1714 return (0); 1715 n = 0; 1716 td = curthread; 1717 for (lle = td->td_sleeplocks; lle != NULL; lle = lle->ll_next) 1718 for (i = lle->ll_count - 1; i >= 0; i--) { 1719 lock1 = &lle->ll_children[i]; 1720 if (lock1->li_lock == lock) 1721 continue; 1722 if (flags & WARN_GIANTOK && 1723 lock1->li_lock == &Giant.lock_object) 1724 continue; 1725 if (flags & WARN_SLEEPOK && 1726 (lock1->li_lock->lo_flags & LO_SLEEPABLE) != 0) 1727 continue; 1728 if (n == 0) { 1729 va_start(ap, fmt); 1730 witness_voutput(fmt, ap); 1731 va_end(ap); 1732 witness_output( 1733 " with the following %slocks held:\n", 1734 (flags & WARN_SLEEPOK) != 0 ? 1735 "non-sleepable " : ""); 1736 } 1737 n++; 1738 witness_list_lock(lock1, witness_output); 1739 } 1740 1741 /* 1742 * Pin the thread in order to avoid problems with thread migration. 1743 * Once that all verifies are passed about spinlocks ownership, 1744 * the thread is in a safe path and it can be unpinned. 1745 */ 1746 sched_pin(); 1747 lock_list = PCPU_GET(spinlocks); 1748 if (lock_list != NULL && lock_list->ll_count != 0) { 1749 sched_unpin(); 1750 1751 /* 1752 * We should only have one spinlock and as long as 1753 * the flags cannot match for this locks class, 1754 * check if the first spinlock is the one curthread 1755 * should hold. 1756 */ 1757 lock1 = &lock_list->ll_children[lock_list->ll_count - 1]; 1758 if (lock_list->ll_count == 1 && lock_list->ll_next == NULL && 1759 lock1->li_lock == lock && n == 0) 1760 return (0); 1761 1762 va_start(ap, fmt); 1763 witness_voutput(fmt, ap); 1764 va_end(ap); 1765 witness_output(" with the following %slocks held:\n", 1766 (flags & WARN_SLEEPOK) != 0 ? "non-sleepable " : ""); 1767 n += witness_list_locks(&lock_list, witness_output); 1768 } else 1769 sched_unpin(); 1770 if (flags & WARN_PANIC && n) 1771 kassert_panic("%s", __func__); 1772 else 1773 witness_debugger(n, __func__); 1774 return (n); 1775 } 1776 1777 const char * 1778 witness_file(struct lock_object *lock) 1779 { 1780 struct witness *w; 1781 1782 if (witness_cold || witness_watch < 1 || lock->lo_witness == NULL) 1783 return ("?"); 1784 w = lock->lo_witness; 1785 return (w->w_file); 1786 } 1787 1788 int 1789 witness_line(struct lock_object *lock) 1790 { 1791 struct witness *w; 1792 1793 if (witness_cold || witness_watch < 1 || lock->lo_witness == NULL) 1794 return (0); 1795 w = lock->lo_witness; 1796 return (w->w_line); 1797 } 1798 1799 static struct witness * 1800 enroll(const char *description, struct lock_class *lock_class) 1801 { 1802 struct witness *w; 1803 struct witness_list *typelist; 1804 1805 MPASS(description != NULL); 1806 1807 if (witness_watch == -1 || panicstr != NULL) 1808 return (NULL); 1809 if ((lock_class->lc_flags & LC_SPINLOCK)) { 1810 if (witness_skipspin) 1811 return (NULL); 1812 else 1813 typelist = &w_spin; 1814 } else if ((lock_class->lc_flags & LC_SLEEPLOCK)) { 1815 typelist = &w_sleep; 1816 } else { 1817 kassert_panic("lock class %s is not sleep or spin", 1818 lock_class->lc_name); 1819 return (NULL); 1820 } 1821 1822 mtx_lock_spin(&w_mtx); 1823 w = witness_hash_get(description); 1824 if (w) 1825 goto found; 1826 if ((w = witness_get()) == NULL) 1827 return (NULL); 1828 MPASS(strlen(description) < MAX_W_NAME); 1829 strcpy(w->w_name, description); 1830 w->w_class = lock_class; 1831 w->w_refcount = 1; 1832 STAILQ_INSERT_HEAD(&w_all, w, w_list); 1833 if (lock_class->lc_flags & LC_SPINLOCK) { 1834 STAILQ_INSERT_HEAD(&w_spin, w, w_typelist); 1835 w_spin_cnt++; 1836 } else if (lock_class->lc_flags & LC_SLEEPLOCK) { 1837 STAILQ_INSERT_HEAD(&w_sleep, w, w_typelist); 1838 w_sleep_cnt++; 1839 } 1840 1841 /* Insert new witness into the hash */ 1842 witness_hash_put(w); 1843 witness_increment_graph_generation(); 1844 mtx_unlock_spin(&w_mtx); 1845 return (w); 1846 found: 1847 w->w_refcount++; 1848 mtx_unlock_spin(&w_mtx); 1849 if (lock_class != w->w_class) 1850 kassert_panic( 1851 "lock (%s) %s does not match earlier (%s) lock", 1852 description, lock_class->lc_name, 1853 w->w_class->lc_name); 1854 return (w); 1855 } 1856 1857 static void 1858 depart(struct witness *w) 1859 { 1860 struct witness_list *list; 1861 1862 MPASS(w->w_refcount == 0); 1863 if (w->w_class->lc_flags & LC_SLEEPLOCK) { 1864 list = &w_sleep; 1865 w_sleep_cnt--; 1866 } else { 1867 list = &w_spin; 1868 w_spin_cnt--; 1869 } 1870 /* 1871 * Set file to NULL as it may point into a loadable module. 1872 */ 1873 w->w_file = NULL; 1874 w->w_line = 0; 1875 witness_increment_graph_generation(); 1876 } 1877 1878 1879 static void 1880 adopt(struct witness *parent, struct witness *child) 1881 { 1882 int pi, ci, i, j; 1883 1884 if (witness_cold == 0) 1885 mtx_assert(&w_mtx, MA_OWNED); 1886 1887 /* If the relationship is already known, there's no work to be done. */ 1888 if (isitmychild(parent, child)) 1889 return; 1890 1891 /* When the structure of the graph changes, bump up the generation. */ 1892 witness_increment_graph_generation(); 1893 1894 /* 1895 * The hard part ... create the direct relationship, then propagate all 1896 * indirect relationships. 1897 */ 1898 pi = parent->w_index; 1899 ci = child->w_index; 1900 WITNESS_INDEX_ASSERT(pi); 1901 WITNESS_INDEX_ASSERT(ci); 1902 MPASS(pi != ci); 1903 w_rmatrix[pi][ci] |= WITNESS_PARENT; 1904 w_rmatrix[ci][pi] |= WITNESS_CHILD; 1905 1906 /* 1907 * If parent was not already an ancestor of child, 1908 * then we increment the descendant and ancestor counters. 1909 */ 1910 if ((w_rmatrix[pi][ci] & WITNESS_ANCESTOR) == 0) { 1911 parent->w_num_descendants++; 1912 child->w_num_ancestors++; 1913 } 1914 1915 /* 1916 * Find each ancestor of 'pi'. Note that 'pi' itself is counted as 1917 * an ancestor of 'pi' during this loop. 1918 */ 1919 for (i = 1; i <= w_max_used_index; i++) { 1920 if ((w_rmatrix[i][pi] & WITNESS_ANCESTOR_MASK) == 0 && 1921 (i != pi)) 1922 continue; 1923 1924 /* Find each descendant of 'i' and mark it as a descendant. */ 1925 for (j = 1; j <= w_max_used_index; j++) { 1926 1927 /* 1928 * Skip children that are already marked as 1929 * descendants of 'i'. 1930 */ 1931 if (w_rmatrix[i][j] & WITNESS_ANCESTOR_MASK) 1932 continue; 1933 1934 /* 1935 * We are only interested in descendants of 'ci'. Note 1936 * that 'ci' itself is counted as a descendant of 'ci'. 1937 */ 1938 if ((w_rmatrix[ci][j] & WITNESS_ANCESTOR_MASK) == 0 && 1939 (j != ci)) 1940 continue; 1941 w_rmatrix[i][j] |= WITNESS_ANCESTOR; 1942 w_rmatrix[j][i] |= WITNESS_DESCENDANT; 1943 w_data[i].w_num_descendants++; 1944 w_data[j].w_num_ancestors++; 1945 1946 /* 1947 * Make sure we aren't marking a node as both an 1948 * ancestor and descendant. We should have caught 1949 * this as a lock order reversal earlier. 1950 */ 1951 if ((w_rmatrix[i][j] & WITNESS_ANCESTOR_MASK) && 1952 (w_rmatrix[i][j] & WITNESS_DESCENDANT_MASK)) { 1953 printf("witness rmatrix paradox! [%d][%d]=%d " 1954 "both ancestor and descendant\n", 1955 i, j, w_rmatrix[i][j]); 1956 kdb_backtrace(); 1957 printf("Witness disabled.\n"); 1958 witness_watch = -1; 1959 } 1960 if ((w_rmatrix[j][i] & WITNESS_ANCESTOR_MASK) && 1961 (w_rmatrix[j][i] & WITNESS_DESCENDANT_MASK)) { 1962 printf("witness rmatrix paradox! [%d][%d]=%d " 1963 "both ancestor and descendant\n", 1964 j, i, w_rmatrix[j][i]); 1965 kdb_backtrace(); 1966 printf("Witness disabled.\n"); 1967 witness_watch = -1; 1968 } 1969 } 1970 } 1971 } 1972 1973 static void 1974 itismychild(struct witness *parent, struct witness *child) 1975 { 1976 int unlocked; 1977 1978 MPASS(child != NULL && parent != NULL); 1979 if (witness_cold == 0) 1980 mtx_assert(&w_mtx, MA_OWNED); 1981 1982 if (!witness_lock_type_equal(parent, child)) { 1983 if (witness_cold == 0) { 1984 unlocked = 1; 1985 mtx_unlock_spin(&w_mtx); 1986 } else { 1987 unlocked = 0; 1988 } 1989 kassert_panic( 1990 "%s: parent \"%s\" (%s) and child \"%s\" (%s) are not " 1991 "the same lock type", __func__, parent->w_name, 1992 parent->w_class->lc_name, child->w_name, 1993 child->w_class->lc_name); 1994 if (unlocked) 1995 mtx_lock_spin(&w_mtx); 1996 } 1997 adopt(parent, child); 1998 } 1999 2000 /* 2001 * Generic code for the isitmy*() functions. The rmask parameter is the 2002 * expected relationship of w1 to w2. 2003 */ 2004 static int 2005 _isitmyx(struct witness *w1, struct witness *w2, int rmask, const char *fname) 2006 { 2007 unsigned char r1, r2; 2008 int i1, i2; 2009 2010 i1 = w1->w_index; 2011 i2 = w2->w_index; 2012 WITNESS_INDEX_ASSERT(i1); 2013 WITNESS_INDEX_ASSERT(i2); 2014 r1 = w_rmatrix[i1][i2] & WITNESS_RELATED_MASK; 2015 r2 = w_rmatrix[i2][i1] & WITNESS_RELATED_MASK; 2016 2017 /* The flags on one better be the inverse of the flags on the other */ 2018 if (!((WITNESS_ATOD(r1) == r2 && WITNESS_DTOA(r2) == r1) || 2019 (WITNESS_DTOA(r1) == r2 && WITNESS_ATOD(r2) == r1))) { 2020 /* Don't squawk if we're potentially racing with an update. */ 2021 if (!mtx_owned(&w_mtx)) 2022 return (0); 2023 printf("%s: rmatrix mismatch between %s (index %d) and %s " 2024 "(index %d): w_rmatrix[%d][%d] == %hhx but " 2025 "w_rmatrix[%d][%d] == %hhx\n", 2026 fname, w1->w_name, i1, w2->w_name, i2, i1, i2, r1, 2027 i2, i1, r2); 2028 kdb_backtrace(); 2029 printf("Witness disabled.\n"); 2030 witness_watch = -1; 2031 } 2032 return (r1 & rmask); 2033 } 2034 2035 /* 2036 * Checks if @child is a direct child of @parent. 2037 */ 2038 static int 2039 isitmychild(struct witness *parent, struct witness *child) 2040 { 2041 2042 return (_isitmyx(parent, child, WITNESS_PARENT, __func__)); 2043 } 2044 2045 /* 2046 * Checks if @descendant is a direct or inderect descendant of @ancestor. 2047 */ 2048 static int 2049 isitmydescendant(struct witness *ancestor, struct witness *descendant) 2050 { 2051 2052 return (_isitmyx(ancestor, descendant, WITNESS_ANCESTOR_MASK, 2053 __func__)); 2054 } 2055 2056 #ifdef BLESSING 2057 static int 2058 blessed(struct witness *w1, struct witness *w2) 2059 { 2060 int i; 2061 struct witness_blessed *b; 2062 2063 for (i = 0; i < blessed_count; i++) { 2064 b = &blessed_list[i]; 2065 if (strcmp(w1->w_name, b->b_lock1) == 0) { 2066 if (strcmp(w2->w_name, b->b_lock2) == 0) 2067 return (1); 2068 continue; 2069 } 2070 if (strcmp(w1->w_name, b->b_lock2) == 0) 2071 if (strcmp(w2->w_name, b->b_lock1) == 0) 2072 return (1); 2073 } 2074 return (0); 2075 } 2076 #endif 2077 2078 static struct witness * 2079 witness_get(void) 2080 { 2081 struct witness *w; 2082 int index; 2083 2084 if (witness_cold == 0) 2085 mtx_assert(&w_mtx, MA_OWNED); 2086 2087 if (witness_watch == -1) { 2088 mtx_unlock_spin(&w_mtx); 2089 return (NULL); 2090 } 2091 if (STAILQ_EMPTY(&w_free)) { 2092 witness_watch = -1; 2093 mtx_unlock_spin(&w_mtx); 2094 printf("WITNESS: unable to allocate a new witness object\n"); 2095 return (NULL); 2096 } 2097 w = STAILQ_FIRST(&w_free); 2098 STAILQ_REMOVE_HEAD(&w_free, w_list); 2099 w_free_cnt--; 2100 index = w->w_index; 2101 MPASS(index > 0 && index == w_max_used_index+1 && 2102 index < witness_count); 2103 bzero(w, sizeof(*w)); 2104 w->w_index = index; 2105 if (index > w_max_used_index) 2106 w_max_used_index = index; 2107 return (w); 2108 } 2109 2110 static void 2111 witness_free(struct witness *w) 2112 { 2113 2114 STAILQ_INSERT_HEAD(&w_free, w, w_list); 2115 w_free_cnt++; 2116 } 2117 2118 static struct lock_list_entry * 2119 witness_lock_list_get(void) 2120 { 2121 struct lock_list_entry *lle; 2122 2123 if (witness_watch == -1) 2124 return (NULL); 2125 mtx_lock_spin(&w_mtx); 2126 lle = w_lock_list_free; 2127 if (lle == NULL) { 2128 witness_watch = -1; 2129 mtx_unlock_spin(&w_mtx); 2130 printf("%s: witness exhausted\n", __func__); 2131 return (NULL); 2132 } 2133 w_lock_list_free = lle->ll_next; 2134 mtx_unlock_spin(&w_mtx); 2135 bzero(lle, sizeof(*lle)); 2136 return (lle); 2137 } 2138 2139 static void 2140 witness_lock_list_free(struct lock_list_entry *lle) 2141 { 2142 2143 mtx_lock_spin(&w_mtx); 2144 lle->ll_next = w_lock_list_free; 2145 w_lock_list_free = lle; 2146 mtx_unlock_spin(&w_mtx); 2147 } 2148 2149 static struct lock_instance * 2150 find_instance(struct lock_list_entry *list, const struct lock_object *lock) 2151 { 2152 struct lock_list_entry *lle; 2153 struct lock_instance *instance; 2154 int i; 2155 2156 for (lle = list; lle != NULL; lle = lle->ll_next) 2157 for (i = lle->ll_count - 1; i >= 0; i--) { 2158 instance = &lle->ll_children[i]; 2159 if (instance->li_lock == lock) 2160 return (instance); 2161 } 2162 return (NULL); 2163 } 2164 2165 static void 2166 witness_list_lock(struct lock_instance *instance, 2167 int (*prnt)(const char *fmt, ...)) 2168 { 2169 struct lock_object *lock; 2170 2171 lock = instance->li_lock; 2172 prnt("%s %s %s", (instance->li_flags & LI_EXCLUSIVE) != 0 ? 2173 "exclusive" : "shared", LOCK_CLASS(lock)->lc_name, lock->lo_name); 2174 if (lock->lo_witness->w_name != lock->lo_name) 2175 prnt(" (%s)", lock->lo_witness->w_name); 2176 prnt(" r = %d (%p) locked @ %s:%d\n", 2177 instance->li_flags & LI_RECURSEMASK, lock, 2178 fixup_filename(instance->li_file), instance->li_line); 2179 } 2180 2181 static int 2182 witness_output(const char *fmt, ...) 2183 { 2184 va_list ap; 2185 int ret; 2186 2187 va_start(ap, fmt); 2188 ret = witness_voutput(fmt, ap); 2189 va_end(ap); 2190 return (ret); 2191 } 2192 2193 static int 2194 witness_voutput(const char *fmt, va_list ap) 2195 { 2196 int ret; 2197 2198 ret = 0; 2199 switch (witness_channel) { 2200 case WITNESS_CONSOLE: 2201 ret = vprintf(fmt, ap); 2202 break; 2203 case WITNESS_LOG: 2204 vlog(LOG_NOTICE, fmt, ap); 2205 break; 2206 case WITNESS_NONE: 2207 break; 2208 } 2209 return (ret); 2210 } 2211 2212 #ifdef DDB 2213 static int 2214 witness_thread_has_locks(struct thread *td) 2215 { 2216 2217 if (td->td_sleeplocks == NULL) 2218 return (0); 2219 return (td->td_sleeplocks->ll_count != 0); 2220 } 2221 2222 static int 2223 witness_proc_has_locks(struct proc *p) 2224 { 2225 struct thread *td; 2226 2227 FOREACH_THREAD_IN_PROC(p, td) { 2228 if (witness_thread_has_locks(td)) 2229 return (1); 2230 } 2231 return (0); 2232 } 2233 #endif 2234 2235 int 2236 witness_list_locks(struct lock_list_entry **lock_list, 2237 int (*prnt)(const char *fmt, ...)) 2238 { 2239 struct lock_list_entry *lle; 2240 int i, nheld; 2241 2242 nheld = 0; 2243 for (lle = *lock_list; lle != NULL; lle = lle->ll_next) 2244 for (i = lle->ll_count - 1; i >= 0; i--) { 2245 witness_list_lock(&lle->ll_children[i], prnt); 2246 nheld++; 2247 } 2248 return (nheld); 2249 } 2250 2251 /* 2252 * This is a bit risky at best. We call this function when we have timed 2253 * out acquiring a spin lock, and we assume that the other CPU is stuck 2254 * with this lock held. So, we go groveling around in the other CPU's 2255 * per-cpu data to try to find the lock instance for this spin lock to 2256 * see when it was last acquired. 2257 */ 2258 void 2259 witness_display_spinlock(struct lock_object *lock, struct thread *owner, 2260 int (*prnt)(const char *fmt, ...)) 2261 { 2262 struct lock_instance *instance; 2263 struct pcpu *pc; 2264 2265 if (owner->td_critnest == 0 || owner->td_oncpu == NOCPU) 2266 return; 2267 pc = pcpu_find(owner->td_oncpu); 2268 instance = find_instance(pc->pc_spinlocks, lock); 2269 if (instance != NULL) 2270 witness_list_lock(instance, prnt); 2271 } 2272 2273 void 2274 witness_save(struct lock_object *lock, const char **filep, int *linep) 2275 { 2276 struct lock_list_entry *lock_list; 2277 struct lock_instance *instance; 2278 struct lock_class *class; 2279 2280 /* 2281 * This function is used independently in locking code to deal with 2282 * Giant, SCHEDULER_STOPPED() check can be removed here after Giant 2283 * is gone. 2284 */ 2285 if (SCHEDULER_STOPPED()) 2286 return; 2287 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); 2288 if (lock->lo_witness == NULL || witness_watch == -1 || panicstr != NULL) 2289 return; 2290 class = LOCK_CLASS(lock); 2291 if (class->lc_flags & LC_SLEEPLOCK) 2292 lock_list = curthread->td_sleeplocks; 2293 else { 2294 if (witness_skipspin) 2295 return; 2296 lock_list = PCPU_GET(spinlocks); 2297 } 2298 instance = find_instance(lock_list, lock); 2299 if (instance == NULL) { 2300 kassert_panic("%s: lock (%s) %s not locked", __func__, 2301 class->lc_name, lock->lo_name); 2302 return; 2303 } 2304 *filep = instance->li_file; 2305 *linep = instance->li_line; 2306 } 2307 2308 void 2309 witness_restore(struct lock_object *lock, const char *file, int line) 2310 { 2311 struct lock_list_entry *lock_list; 2312 struct lock_instance *instance; 2313 struct lock_class *class; 2314 2315 /* 2316 * This function is used independently in locking code to deal with 2317 * Giant, SCHEDULER_STOPPED() check can be removed here after Giant 2318 * is gone. 2319 */ 2320 if (SCHEDULER_STOPPED()) 2321 return; 2322 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); 2323 if (lock->lo_witness == NULL || witness_watch == -1 || panicstr != NULL) 2324 return; 2325 class = LOCK_CLASS(lock); 2326 if (class->lc_flags & LC_SLEEPLOCK) 2327 lock_list = curthread->td_sleeplocks; 2328 else { 2329 if (witness_skipspin) 2330 return; 2331 lock_list = PCPU_GET(spinlocks); 2332 } 2333 instance = find_instance(lock_list, lock); 2334 if (instance == NULL) 2335 kassert_panic("%s: lock (%s) %s not locked", __func__, 2336 class->lc_name, lock->lo_name); 2337 lock->lo_witness->w_file = file; 2338 lock->lo_witness->w_line = line; 2339 if (instance == NULL) 2340 return; 2341 instance->li_file = file; 2342 instance->li_line = line; 2343 } 2344 2345 void 2346 witness_assert(const struct lock_object *lock, int flags, const char *file, 2347 int line) 2348 { 2349 #ifdef INVARIANT_SUPPORT 2350 struct lock_instance *instance; 2351 struct lock_class *class; 2352 2353 if (lock->lo_witness == NULL || witness_watch < 1 || panicstr != NULL) 2354 return; 2355 class = LOCK_CLASS(lock); 2356 if ((class->lc_flags & LC_SLEEPLOCK) != 0) 2357 instance = find_instance(curthread->td_sleeplocks, lock); 2358 else if ((class->lc_flags & LC_SPINLOCK) != 0) 2359 instance = find_instance(PCPU_GET(spinlocks), lock); 2360 else { 2361 kassert_panic("Lock (%s) %s is not sleep or spin!", 2362 class->lc_name, lock->lo_name); 2363 return; 2364 } 2365 switch (flags) { 2366 case LA_UNLOCKED: 2367 if (instance != NULL) 2368 kassert_panic("Lock (%s) %s locked @ %s:%d.", 2369 class->lc_name, lock->lo_name, 2370 fixup_filename(file), line); 2371 break; 2372 case LA_LOCKED: 2373 case LA_LOCKED | LA_RECURSED: 2374 case LA_LOCKED | LA_NOTRECURSED: 2375 case LA_SLOCKED: 2376 case LA_SLOCKED | LA_RECURSED: 2377 case LA_SLOCKED | LA_NOTRECURSED: 2378 case LA_XLOCKED: 2379 case LA_XLOCKED | LA_RECURSED: 2380 case LA_XLOCKED | LA_NOTRECURSED: 2381 if (instance == NULL) { 2382 kassert_panic("Lock (%s) %s not locked @ %s:%d.", 2383 class->lc_name, lock->lo_name, 2384 fixup_filename(file), line); 2385 break; 2386 } 2387 if ((flags & LA_XLOCKED) != 0 && 2388 (instance->li_flags & LI_EXCLUSIVE) == 0) 2389 kassert_panic( 2390 "Lock (%s) %s not exclusively locked @ %s:%d.", 2391 class->lc_name, lock->lo_name, 2392 fixup_filename(file), line); 2393 if ((flags & LA_SLOCKED) != 0 && 2394 (instance->li_flags & LI_EXCLUSIVE) != 0) 2395 kassert_panic( 2396 "Lock (%s) %s exclusively locked @ %s:%d.", 2397 class->lc_name, lock->lo_name, 2398 fixup_filename(file), line); 2399 if ((flags & LA_RECURSED) != 0 && 2400 (instance->li_flags & LI_RECURSEMASK) == 0) 2401 kassert_panic("Lock (%s) %s not recursed @ %s:%d.", 2402 class->lc_name, lock->lo_name, 2403 fixup_filename(file), line); 2404 if ((flags & LA_NOTRECURSED) != 0 && 2405 (instance->li_flags & LI_RECURSEMASK) != 0) 2406 kassert_panic("Lock (%s) %s recursed @ %s:%d.", 2407 class->lc_name, lock->lo_name, 2408 fixup_filename(file), line); 2409 break; 2410 default: 2411 kassert_panic("Invalid lock assertion at %s:%d.", 2412 fixup_filename(file), line); 2413 2414 } 2415 #endif /* INVARIANT_SUPPORT */ 2416 } 2417 2418 static void 2419 witness_setflag(struct lock_object *lock, int flag, int set) 2420 { 2421 struct lock_list_entry *lock_list; 2422 struct lock_instance *instance; 2423 struct lock_class *class; 2424 2425 if (lock->lo_witness == NULL || witness_watch == -1 || panicstr != NULL) 2426 return; 2427 class = LOCK_CLASS(lock); 2428 if (class->lc_flags & LC_SLEEPLOCK) 2429 lock_list = curthread->td_sleeplocks; 2430 else { 2431 if (witness_skipspin) 2432 return; 2433 lock_list = PCPU_GET(spinlocks); 2434 } 2435 instance = find_instance(lock_list, lock); 2436 if (instance == NULL) { 2437 kassert_panic("%s: lock (%s) %s not locked", __func__, 2438 class->lc_name, lock->lo_name); 2439 return; 2440 } 2441 2442 if (set) 2443 instance->li_flags |= flag; 2444 else 2445 instance->li_flags &= ~flag; 2446 } 2447 2448 void 2449 witness_norelease(struct lock_object *lock) 2450 { 2451 2452 witness_setflag(lock, LI_NORELEASE, 1); 2453 } 2454 2455 void 2456 witness_releaseok(struct lock_object *lock) 2457 { 2458 2459 witness_setflag(lock, LI_NORELEASE, 0); 2460 } 2461 2462 #ifdef DDB 2463 static void 2464 witness_ddb_list(struct thread *td) 2465 { 2466 2467 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); 2468 KASSERT(kdb_active, ("%s: not in the debugger", __func__)); 2469 2470 if (witness_watch < 1) 2471 return; 2472 2473 witness_list_locks(&td->td_sleeplocks, db_printf); 2474 2475 /* 2476 * We only handle spinlocks if td == curthread. This is somewhat broken 2477 * if td is currently executing on some other CPU and holds spin locks 2478 * as we won't display those locks. If we had a MI way of getting 2479 * the per-cpu data for a given cpu then we could use 2480 * td->td_oncpu to get the list of spinlocks for this thread 2481 * and "fix" this. 2482 * 2483 * That still wouldn't really fix this unless we locked the scheduler 2484 * lock or stopped the other CPU to make sure it wasn't changing the 2485 * list out from under us. It is probably best to just not try to 2486 * handle threads on other CPU's for now. 2487 */ 2488 if (td == curthread && PCPU_GET(spinlocks) != NULL) 2489 witness_list_locks(PCPU_PTR(spinlocks), db_printf); 2490 } 2491 2492 DB_SHOW_COMMAND(locks, db_witness_list) 2493 { 2494 struct thread *td; 2495 2496 if (have_addr) 2497 td = db_lookup_thread(addr, true); 2498 else 2499 td = kdb_thread; 2500 witness_ddb_list(td); 2501 } 2502 2503 DB_SHOW_ALL_COMMAND(locks, db_witness_list_all) 2504 { 2505 struct thread *td; 2506 struct proc *p; 2507 2508 /* 2509 * It would be nice to list only threads and processes that actually 2510 * held sleep locks, but that information is currently not exported 2511 * by WITNESS. 2512 */ 2513 FOREACH_PROC_IN_SYSTEM(p) { 2514 if (!witness_proc_has_locks(p)) 2515 continue; 2516 FOREACH_THREAD_IN_PROC(p, td) { 2517 if (!witness_thread_has_locks(td)) 2518 continue; 2519 db_printf("Process %d (%s) thread %p (%d)\n", p->p_pid, 2520 p->p_comm, td, td->td_tid); 2521 witness_ddb_list(td); 2522 if (db_pager_quit) 2523 return; 2524 } 2525 } 2526 } 2527 DB_SHOW_ALIAS(alllocks, db_witness_list_all) 2528 2529 DB_SHOW_COMMAND(witness, db_witness_display) 2530 { 2531 2532 witness_ddb_display(db_printf); 2533 } 2534 #endif 2535 2536 static int 2537 sysctl_debug_witness_badstacks(SYSCTL_HANDLER_ARGS) 2538 { 2539 struct witness_lock_order_data *data1, *data2, *tmp_data1, *tmp_data2; 2540 struct witness *tmp_w1, *tmp_w2, *w1, *w2; 2541 struct sbuf *sb; 2542 u_int w_rmatrix1, w_rmatrix2; 2543 int error, generation, i, j; 2544 2545 tmp_data1 = NULL; 2546 tmp_data2 = NULL; 2547 tmp_w1 = NULL; 2548 tmp_w2 = NULL; 2549 if (witness_watch < 1) { 2550 error = SYSCTL_OUT(req, w_notrunning, sizeof(w_notrunning)); 2551 return (error); 2552 } 2553 if (witness_cold) { 2554 error = SYSCTL_OUT(req, w_stillcold, sizeof(w_stillcold)); 2555 return (error); 2556 } 2557 error = 0; 2558 sb = sbuf_new(NULL, NULL, badstack_sbuf_size, SBUF_AUTOEXTEND); 2559 if (sb == NULL) 2560 return (ENOMEM); 2561 2562 /* Allocate and init temporary storage space. */ 2563 tmp_w1 = malloc(sizeof(struct witness), M_TEMP, M_WAITOK | M_ZERO); 2564 tmp_w2 = malloc(sizeof(struct witness), M_TEMP, M_WAITOK | M_ZERO); 2565 tmp_data1 = malloc(sizeof(struct witness_lock_order_data), M_TEMP, 2566 M_WAITOK | M_ZERO); 2567 tmp_data2 = malloc(sizeof(struct witness_lock_order_data), M_TEMP, 2568 M_WAITOK | M_ZERO); 2569 stack_zero(&tmp_data1->wlod_stack); 2570 stack_zero(&tmp_data2->wlod_stack); 2571 2572 restart: 2573 mtx_lock_spin(&w_mtx); 2574 generation = w_generation; 2575 mtx_unlock_spin(&w_mtx); 2576 sbuf_printf(sb, "Number of known direct relationships is %d\n", 2577 w_lohash.wloh_count); 2578 for (i = 1; i < w_max_used_index; i++) { 2579 mtx_lock_spin(&w_mtx); 2580 if (generation != w_generation) { 2581 mtx_unlock_spin(&w_mtx); 2582 2583 /* The graph has changed, try again. */ 2584 req->oldidx = 0; 2585 sbuf_clear(sb); 2586 goto restart; 2587 } 2588 2589 w1 = &w_data[i]; 2590 if (w1->w_reversed == 0) { 2591 mtx_unlock_spin(&w_mtx); 2592 continue; 2593 } 2594 2595 /* Copy w1 locally so we can release the spin lock. */ 2596 *tmp_w1 = *w1; 2597 mtx_unlock_spin(&w_mtx); 2598 2599 if (tmp_w1->w_reversed == 0) 2600 continue; 2601 for (j = 1; j < w_max_used_index; j++) { 2602 if ((w_rmatrix[i][j] & WITNESS_REVERSAL) == 0 || i > j) 2603 continue; 2604 2605 mtx_lock_spin(&w_mtx); 2606 if (generation != w_generation) { 2607 mtx_unlock_spin(&w_mtx); 2608 2609 /* The graph has changed, try again. */ 2610 req->oldidx = 0; 2611 sbuf_clear(sb); 2612 goto restart; 2613 } 2614 2615 w2 = &w_data[j]; 2616 data1 = witness_lock_order_get(w1, w2); 2617 data2 = witness_lock_order_get(w2, w1); 2618 2619 /* 2620 * Copy information locally so we can release the 2621 * spin lock. 2622 */ 2623 *tmp_w2 = *w2; 2624 w_rmatrix1 = (unsigned int)w_rmatrix[i][j]; 2625 w_rmatrix2 = (unsigned int)w_rmatrix[j][i]; 2626 2627 if (data1) { 2628 stack_zero(&tmp_data1->wlod_stack); 2629 stack_copy(&data1->wlod_stack, 2630 &tmp_data1->wlod_stack); 2631 } 2632 if (data2 && data2 != data1) { 2633 stack_zero(&tmp_data2->wlod_stack); 2634 stack_copy(&data2->wlod_stack, 2635 &tmp_data2->wlod_stack); 2636 } 2637 mtx_unlock_spin(&w_mtx); 2638 2639 sbuf_printf(sb, 2640 "\nLock order reversal between \"%s\"(%s) and \"%s\"(%s)!\n", 2641 tmp_w1->w_name, tmp_w1->w_class->lc_name, 2642 tmp_w2->w_name, tmp_w2->w_class->lc_name); 2643 if (data1) { 2644 sbuf_printf(sb, 2645 "Lock order \"%s\"(%s) -> \"%s\"(%s) first seen at:\n", 2646 tmp_w1->w_name, tmp_w1->w_class->lc_name, 2647 tmp_w2->w_name, tmp_w2->w_class->lc_name); 2648 stack_sbuf_print(sb, &tmp_data1->wlod_stack); 2649 sbuf_printf(sb, "\n"); 2650 } 2651 if (data2 && data2 != data1) { 2652 sbuf_printf(sb, 2653 "Lock order \"%s\"(%s) -> \"%s\"(%s) first seen at:\n", 2654 tmp_w2->w_name, tmp_w2->w_class->lc_name, 2655 tmp_w1->w_name, tmp_w1->w_class->lc_name); 2656 stack_sbuf_print(sb, &tmp_data2->wlod_stack); 2657 sbuf_printf(sb, "\n"); 2658 } 2659 } 2660 } 2661 mtx_lock_spin(&w_mtx); 2662 if (generation != w_generation) { 2663 mtx_unlock_spin(&w_mtx); 2664 2665 /* 2666 * The graph changed while we were printing stack data, 2667 * try again. 2668 */ 2669 req->oldidx = 0; 2670 sbuf_clear(sb); 2671 goto restart; 2672 } 2673 mtx_unlock_spin(&w_mtx); 2674 2675 /* Free temporary storage space. */ 2676 free(tmp_data1, M_TEMP); 2677 free(tmp_data2, M_TEMP); 2678 free(tmp_w1, M_TEMP); 2679 free(tmp_w2, M_TEMP); 2680 2681 sbuf_finish(sb); 2682 error = SYSCTL_OUT(req, sbuf_data(sb), sbuf_len(sb) + 1); 2683 sbuf_delete(sb); 2684 2685 return (error); 2686 } 2687 2688 static int 2689 sysctl_debug_witness_channel(SYSCTL_HANDLER_ARGS) 2690 { 2691 static const struct { 2692 enum witness_channel channel; 2693 const char *name; 2694 } channels[] = { 2695 { WITNESS_CONSOLE, "console" }, 2696 { WITNESS_LOG, "log" }, 2697 { WITNESS_NONE, "none" }, 2698 }; 2699 char buf[16]; 2700 u_int i; 2701 int error; 2702 2703 buf[0] = '\0'; 2704 for (i = 0; i < nitems(channels); i++) 2705 if (witness_channel == channels[i].channel) { 2706 snprintf(buf, sizeof(buf), "%s", channels[i].name); 2707 break; 2708 } 2709 2710 error = sysctl_handle_string(oidp, buf, sizeof(buf), req); 2711 if (error != 0 || req->newptr == NULL) 2712 return (error); 2713 2714 error = EINVAL; 2715 for (i = 0; i < nitems(channels); i++) 2716 if (strcmp(channels[i].name, buf) == 0) { 2717 witness_channel = channels[i].channel; 2718 error = 0; 2719 break; 2720 } 2721 return (error); 2722 } 2723 2724 static int 2725 sysctl_debug_witness_fullgraph(SYSCTL_HANDLER_ARGS) 2726 { 2727 struct witness *w; 2728 struct sbuf *sb; 2729 int error; 2730 2731 if (witness_watch < 1) { 2732 error = SYSCTL_OUT(req, w_notrunning, sizeof(w_notrunning)); 2733 return (error); 2734 } 2735 if (witness_cold) { 2736 error = SYSCTL_OUT(req, w_stillcold, sizeof(w_stillcold)); 2737 return (error); 2738 } 2739 error = 0; 2740 2741 error = sysctl_wire_old_buffer(req, 0); 2742 if (error != 0) 2743 return (error); 2744 sb = sbuf_new_for_sysctl(NULL, NULL, FULLGRAPH_SBUF_SIZE, req); 2745 if (sb == NULL) 2746 return (ENOMEM); 2747 sbuf_printf(sb, "\n"); 2748 2749 mtx_lock_spin(&w_mtx); 2750 STAILQ_FOREACH(w, &w_all, w_list) 2751 w->w_displayed = 0; 2752 STAILQ_FOREACH(w, &w_all, w_list) 2753 witness_add_fullgraph(sb, w); 2754 mtx_unlock_spin(&w_mtx); 2755 2756 /* 2757 * Close the sbuf and return to userland. 2758 */ 2759 error = sbuf_finish(sb); 2760 sbuf_delete(sb); 2761 2762 return (error); 2763 } 2764 2765 static int 2766 sysctl_debug_witness_watch(SYSCTL_HANDLER_ARGS) 2767 { 2768 int error, value; 2769 2770 value = witness_watch; 2771 error = sysctl_handle_int(oidp, &value, 0, req); 2772 if (error != 0 || req->newptr == NULL) 2773 return (error); 2774 if (value > 1 || value < -1 || 2775 (witness_watch == -1 && value != witness_watch)) 2776 return (EINVAL); 2777 witness_watch = value; 2778 return (0); 2779 } 2780 2781 static void 2782 witness_add_fullgraph(struct sbuf *sb, struct witness *w) 2783 { 2784 int i; 2785 2786 if (w->w_displayed != 0 || (w->w_file == NULL && w->w_line == 0)) 2787 return; 2788 w->w_displayed = 1; 2789 2790 WITNESS_INDEX_ASSERT(w->w_index); 2791 for (i = 1; i <= w_max_used_index; i++) { 2792 if (w_rmatrix[w->w_index][i] & WITNESS_PARENT) { 2793 sbuf_printf(sb, "\"%s\",\"%s\"\n", w->w_name, 2794 w_data[i].w_name); 2795 witness_add_fullgraph(sb, &w_data[i]); 2796 } 2797 } 2798 } 2799 2800 /* 2801 * A simple hash function. Takes a key pointer and a key size. If size == 0, 2802 * interprets the key as a string and reads until the null 2803 * terminator. Otherwise, reads the first size bytes. Returns an unsigned 32-bit 2804 * hash value computed from the key. 2805 */ 2806 static uint32_t 2807 witness_hash_djb2(const uint8_t *key, uint32_t size) 2808 { 2809 unsigned int hash = 5381; 2810 int i; 2811 2812 /* hash = hash * 33 + key[i] */ 2813 if (size) 2814 for (i = 0; i < size; i++) 2815 hash = ((hash << 5) + hash) + (unsigned int)key[i]; 2816 else 2817 for (i = 0; key[i] != 0; i++) 2818 hash = ((hash << 5) + hash) + (unsigned int)key[i]; 2819 2820 return (hash); 2821 } 2822 2823 2824 /* 2825 * Initializes the two witness hash tables. Called exactly once from 2826 * witness_initialize(). 2827 */ 2828 static void 2829 witness_init_hash_tables(void) 2830 { 2831 int i; 2832 2833 MPASS(witness_cold); 2834 2835 /* Initialize the hash tables. */ 2836 for (i = 0; i < WITNESS_HASH_SIZE; i++) 2837 w_hash.wh_array[i] = NULL; 2838 2839 w_hash.wh_size = WITNESS_HASH_SIZE; 2840 w_hash.wh_count = 0; 2841 2842 /* Initialize the lock order data hash. */ 2843 w_lofree = NULL; 2844 for (i = 0; i < WITNESS_LO_DATA_COUNT; i++) { 2845 memset(&w_lodata[i], 0, sizeof(w_lodata[i])); 2846 w_lodata[i].wlod_next = w_lofree; 2847 w_lofree = &w_lodata[i]; 2848 } 2849 w_lohash.wloh_size = WITNESS_LO_HASH_SIZE; 2850 w_lohash.wloh_count = 0; 2851 for (i = 0; i < WITNESS_LO_HASH_SIZE; i++) 2852 w_lohash.wloh_array[i] = NULL; 2853 } 2854 2855 static struct witness * 2856 witness_hash_get(const char *key) 2857 { 2858 struct witness *w; 2859 uint32_t hash; 2860 2861 MPASS(key != NULL); 2862 if (witness_cold == 0) 2863 mtx_assert(&w_mtx, MA_OWNED); 2864 hash = witness_hash_djb2(key, 0) % w_hash.wh_size; 2865 w = w_hash.wh_array[hash]; 2866 while (w != NULL) { 2867 if (strcmp(w->w_name, key) == 0) 2868 goto out; 2869 w = w->w_hash_next; 2870 } 2871 2872 out: 2873 return (w); 2874 } 2875 2876 static void 2877 witness_hash_put(struct witness *w) 2878 { 2879 uint32_t hash; 2880 2881 MPASS(w != NULL); 2882 MPASS(w->w_name != NULL); 2883 if (witness_cold == 0) 2884 mtx_assert(&w_mtx, MA_OWNED); 2885 KASSERT(witness_hash_get(w->w_name) == NULL, 2886 ("%s: trying to add a hash entry that already exists!", __func__)); 2887 KASSERT(w->w_hash_next == NULL, 2888 ("%s: w->w_hash_next != NULL", __func__)); 2889 2890 hash = witness_hash_djb2(w->w_name, 0) % w_hash.wh_size; 2891 w->w_hash_next = w_hash.wh_array[hash]; 2892 w_hash.wh_array[hash] = w; 2893 w_hash.wh_count++; 2894 } 2895 2896 2897 static struct witness_lock_order_data * 2898 witness_lock_order_get(struct witness *parent, struct witness *child) 2899 { 2900 struct witness_lock_order_data *data = NULL; 2901 struct witness_lock_order_key key; 2902 unsigned int hash; 2903 2904 MPASS(parent != NULL && child != NULL); 2905 key.from = parent->w_index; 2906 key.to = child->w_index; 2907 WITNESS_INDEX_ASSERT(key.from); 2908 WITNESS_INDEX_ASSERT(key.to); 2909 if ((w_rmatrix[parent->w_index][child->w_index] 2910 & WITNESS_LOCK_ORDER_KNOWN) == 0) 2911 goto out; 2912 2913 hash = witness_hash_djb2((const char*)&key, 2914 sizeof(key)) % w_lohash.wloh_size; 2915 data = w_lohash.wloh_array[hash]; 2916 while (data != NULL) { 2917 if (witness_lock_order_key_equal(&data->wlod_key, &key)) 2918 break; 2919 data = data->wlod_next; 2920 } 2921 2922 out: 2923 return (data); 2924 } 2925 2926 /* 2927 * Verify that parent and child have a known relationship, are not the same, 2928 * and child is actually a child of parent. This is done without w_mtx 2929 * to avoid contention in the common case. 2930 */ 2931 static int 2932 witness_lock_order_check(struct witness *parent, struct witness *child) 2933 { 2934 2935 if (parent != child && 2936 w_rmatrix[parent->w_index][child->w_index] 2937 & WITNESS_LOCK_ORDER_KNOWN && 2938 isitmychild(parent, child)) 2939 return (1); 2940 2941 return (0); 2942 } 2943 2944 static int 2945 witness_lock_order_add(struct witness *parent, struct witness *child) 2946 { 2947 struct witness_lock_order_data *data = NULL; 2948 struct witness_lock_order_key key; 2949 unsigned int hash; 2950 2951 MPASS(parent != NULL && child != NULL); 2952 key.from = parent->w_index; 2953 key.to = child->w_index; 2954 WITNESS_INDEX_ASSERT(key.from); 2955 WITNESS_INDEX_ASSERT(key.to); 2956 if (w_rmatrix[parent->w_index][child->w_index] 2957 & WITNESS_LOCK_ORDER_KNOWN) 2958 return (1); 2959 2960 hash = witness_hash_djb2((const char*)&key, 2961 sizeof(key)) % w_lohash.wloh_size; 2962 w_rmatrix[parent->w_index][child->w_index] |= WITNESS_LOCK_ORDER_KNOWN; 2963 data = w_lofree; 2964 if (data == NULL) 2965 return (0); 2966 w_lofree = data->wlod_next; 2967 data->wlod_next = w_lohash.wloh_array[hash]; 2968 data->wlod_key = key; 2969 w_lohash.wloh_array[hash] = data; 2970 w_lohash.wloh_count++; 2971 stack_zero(&data->wlod_stack); 2972 stack_save(&data->wlod_stack); 2973 return (1); 2974 } 2975 2976 /* Call this whenver the structure of the witness graph changes. */ 2977 static void 2978 witness_increment_graph_generation(void) 2979 { 2980 2981 if (witness_cold == 0) 2982 mtx_assert(&w_mtx, MA_OWNED); 2983 w_generation++; 2984 } 2985 2986 static int 2987 witness_output_drain(void *arg __unused, const char *data, int len) 2988 { 2989 2990 witness_output("%.*s", len, data); 2991 return (len); 2992 } 2993 2994 static void 2995 witness_debugger(int cond, const char *msg) 2996 { 2997 char buf[32]; 2998 struct sbuf sb; 2999 struct stack st; 3000 3001 if (!cond) 3002 return; 3003 3004 if (witness_trace) { 3005 sbuf_new(&sb, buf, sizeof(buf), SBUF_FIXEDLEN); 3006 sbuf_set_drain(&sb, witness_output_drain, NULL); 3007 3008 stack_zero(&st); 3009 stack_save(&st); 3010 witness_output("stack backtrace:\n"); 3011 stack_sbuf_print_ddb(&sb, &st); 3012 3013 sbuf_finish(&sb); 3014 } 3015 3016 #ifdef KDB 3017 if (witness_kdb) 3018 kdb_enter(KDB_WHY_WITNESS, msg); 3019 #endif 3020 } 3021