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