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 pagequeue", &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 pagequeue", &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 * VFS namecache 627 */ 628 { "ncvn", &lock_class_mtx_sleep }, 629 { "ncbuc", &lock_class_rw }, 630 { "vnode interlock", &lock_class_mtx_sleep }, 631 { "ncneg", &lock_class_mtx_sleep }, 632 { NULL, NULL }, 633 /* 634 * ZFS locking 635 */ 636 { "dn->dn_mtx", &lock_class_sx }, 637 { "dr->dt.di.dr_mtx", &lock_class_sx }, 638 { "db->db_mtx", &lock_class_sx }, 639 { NULL, NULL }, 640 /* 641 * spin locks 642 */ 643 #ifdef SMP 644 { "ap boot", &lock_class_mtx_spin }, 645 #endif 646 { "rm.mutex_mtx", &lock_class_mtx_spin }, 647 { "sio", &lock_class_mtx_spin }, 648 #ifdef __i386__ 649 { "cy", &lock_class_mtx_spin }, 650 #endif 651 #ifdef __sparc64__ 652 { "pcib_mtx", &lock_class_mtx_spin }, 653 { "rtc_mtx", &lock_class_mtx_spin }, 654 #endif 655 { "scc_hwmtx", &lock_class_mtx_spin }, 656 { "uart_hwmtx", &lock_class_mtx_spin }, 657 { "fast_taskqueue", &lock_class_mtx_spin }, 658 { "intr table", &lock_class_mtx_spin }, 659 #ifdef HWPMC_HOOKS 660 { "pmc-per-proc", &lock_class_mtx_spin }, 661 #endif 662 { "process slock", &lock_class_mtx_spin }, 663 { "syscons video lock", &lock_class_mtx_spin }, 664 { "sleepq chain", &lock_class_mtx_spin }, 665 { "rm_spinlock", &lock_class_mtx_spin }, 666 { "turnstile chain", &lock_class_mtx_spin }, 667 { "turnstile lock", &lock_class_mtx_spin }, 668 { "sched lock", &lock_class_mtx_spin }, 669 { "td_contested", &lock_class_mtx_spin }, 670 { "callout", &lock_class_mtx_spin }, 671 { "entropy harvest mutex", &lock_class_mtx_spin }, 672 #ifdef SMP 673 { "smp rendezvous", &lock_class_mtx_spin }, 674 #endif 675 #ifdef __powerpc__ 676 { "tlb0", &lock_class_mtx_spin }, 677 #endif 678 /* 679 * leaf locks 680 */ 681 { "intrcnt", &lock_class_mtx_spin }, 682 { "icu", &lock_class_mtx_spin }, 683 #if defined(SMP) && defined(__sparc64__) 684 { "ipi", &lock_class_mtx_spin }, 685 #endif 686 #ifdef __i386__ 687 { "allpmaps", &lock_class_mtx_spin }, 688 { "descriptor tables", &lock_class_mtx_spin }, 689 #endif 690 { "clk", &lock_class_mtx_spin }, 691 { "cpuset", &lock_class_mtx_spin }, 692 { "mprof lock", &lock_class_mtx_spin }, 693 { "zombie lock", &lock_class_mtx_spin }, 694 { "ALD Queue", &lock_class_mtx_spin }, 695 #if defined(__i386__) || defined(__amd64__) 696 { "pcicfg", &lock_class_mtx_spin }, 697 { "NDIS thread lock", &lock_class_mtx_spin }, 698 #endif 699 { "tw_osl_io_lock", &lock_class_mtx_spin }, 700 { "tw_osl_q_lock", &lock_class_mtx_spin }, 701 { "tw_cl_io_lock", &lock_class_mtx_spin }, 702 { "tw_cl_intr_lock", &lock_class_mtx_spin }, 703 { "tw_cl_gen_lock", &lock_class_mtx_spin }, 704 #ifdef HWPMC_HOOKS 705 { "pmc-leaf", &lock_class_mtx_spin }, 706 #endif 707 { "blocked lock", &lock_class_mtx_spin }, 708 { NULL, NULL }, 709 { NULL, NULL } 710 }; 711 712 #ifdef BLESSING 713 /* 714 * Pairs of locks which have been blessed 715 * Don't complain about order problems with blessed locks 716 */ 717 static struct witness_blessed blessed_list[] = { 718 }; 719 #endif 720 721 /* 722 * This global is set to 0 once it becomes safe to use the witness code. 723 */ 724 static int witness_cold = 1; 725 726 /* 727 * This global is set to 1 once the static lock orders have been enrolled 728 * so that a warning can be issued for any spin locks enrolled later. 729 */ 730 static int witness_spin_warn = 0; 731 732 /* Trim useless garbage from filenames. */ 733 static const char * 734 fixup_filename(const char *file) 735 { 736 737 if (file == NULL) 738 return (NULL); 739 while (strncmp(file, "../", 3) == 0) 740 file += 3; 741 return (file); 742 } 743 744 /* 745 * The WITNESS-enabled diagnostic code. Note that the witness code does 746 * assume that the early boot is single-threaded at least until after this 747 * routine is completed. 748 */ 749 static void 750 witness_initialize(void *dummy __unused) 751 { 752 struct lock_object *lock; 753 struct witness_order_list_entry *order; 754 struct witness *w, *w1; 755 int i; 756 757 w_data = malloc(sizeof (struct witness) * witness_count, M_WITNESS, 758 M_WAITOK | M_ZERO); 759 760 w_rmatrix = malloc(sizeof(*w_rmatrix) * (witness_count + 1), 761 M_WITNESS, M_WAITOK | M_ZERO); 762 763 for (i = 0; i < witness_count + 1; i++) { 764 w_rmatrix[i] = malloc(sizeof(*w_rmatrix[i]) * 765 (witness_count + 1), M_WITNESS, M_WAITOK | M_ZERO); 766 } 767 badstack_sbuf_size = witness_count * 256; 768 769 /* 770 * We have to release Giant before initializing its witness 771 * structure so that WITNESS doesn't get confused. 772 */ 773 mtx_unlock(&Giant); 774 mtx_assert(&Giant, MA_NOTOWNED); 775 776 CTR1(KTR_WITNESS, "%s: initializing witness", __func__); 777 mtx_init(&w_mtx, "witness lock", NULL, MTX_SPIN | MTX_QUIET | 778 MTX_NOWITNESS | MTX_NOPROFILE); 779 for (i = witness_count - 1; i >= 0; i--) { 780 w = &w_data[i]; 781 memset(w, 0, sizeof(*w)); 782 w_data[i].w_index = i; /* Witness index never changes. */ 783 witness_free(w); 784 } 785 KASSERT(STAILQ_FIRST(&w_free)->w_index == 0, 786 ("%s: Invalid list of free witness objects", __func__)); 787 788 /* Witness with index 0 is not used to aid in debugging. */ 789 STAILQ_REMOVE_HEAD(&w_free, w_list); 790 w_free_cnt--; 791 792 for (i = 0; i < witness_count; i++) { 793 memset(w_rmatrix[i], 0, sizeof(*w_rmatrix[i]) * 794 (witness_count + 1)); 795 } 796 797 for (i = 0; i < LOCK_CHILDCOUNT; i++) 798 witness_lock_list_free(&w_locklistdata[i]); 799 witness_init_hash_tables(); 800 801 /* First add in all the specified order lists. */ 802 for (order = order_lists; order->w_name != NULL; order++) { 803 w = enroll(order->w_name, order->w_class); 804 if (w == NULL) 805 continue; 806 w->w_file = "order list"; 807 for (order++; order->w_name != NULL; order++) { 808 w1 = enroll(order->w_name, order->w_class); 809 if (w1 == NULL) 810 continue; 811 w1->w_file = "order list"; 812 itismychild(w, w1); 813 w = w1; 814 } 815 } 816 witness_spin_warn = 1; 817 818 /* Iterate through all locks and add them to witness. */ 819 for (i = 0; pending_locks[i].wh_lock != NULL; i++) { 820 lock = pending_locks[i].wh_lock; 821 KASSERT(lock->lo_flags & LO_WITNESS, 822 ("%s: lock %s is on pending list but not LO_WITNESS", 823 __func__, lock->lo_name)); 824 lock->lo_witness = enroll(pending_locks[i].wh_type, 825 LOCK_CLASS(lock)); 826 } 827 828 /* Mark the witness code as being ready for use. */ 829 witness_cold = 0; 830 831 mtx_lock(&Giant); 832 } 833 SYSINIT(witness_init, SI_SUB_WITNESS, SI_ORDER_FIRST, witness_initialize, 834 NULL); 835 836 void 837 witness_init(struct lock_object *lock, const char *type) 838 { 839 struct lock_class *class; 840 841 /* Various sanity checks. */ 842 class = LOCK_CLASS(lock); 843 if ((lock->lo_flags & LO_RECURSABLE) != 0 && 844 (class->lc_flags & LC_RECURSABLE) == 0) 845 kassert_panic("%s: lock (%s) %s can not be recursable", 846 __func__, class->lc_name, lock->lo_name); 847 if ((lock->lo_flags & LO_SLEEPABLE) != 0 && 848 (class->lc_flags & LC_SLEEPABLE) == 0) 849 kassert_panic("%s: lock (%s) %s can not be sleepable", 850 __func__, class->lc_name, lock->lo_name); 851 if ((lock->lo_flags & LO_UPGRADABLE) != 0 && 852 (class->lc_flags & LC_UPGRADABLE) == 0) 853 kassert_panic("%s: lock (%s) %s can not be upgradable", 854 __func__, class->lc_name, lock->lo_name); 855 856 /* 857 * If we shouldn't watch this lock, then just clear lo_witness. 858 * Otherwise, if witness_cold is set, then it is too early to 859 * enroll this lock, so defer it to witness_initialize() by adding 860 * it to the pending_locks list. If it is not too early, then enroll 861 * the lock now. 862 */ 863 if (witness_watch < 1 || panicstr != NULL || 864 (lock->lo_flags & LO_WITNESS) == 0) 865 lock->lo_witness = NULL; 866 else if (witness_cold) { 867 pending_locks[pending_cnt].wh_lock = lock; 868 pending_locks[pending_cnt++].wh_type = type; 869 if (pending_cnt > WITNESS_PENDLIST) 870 panic("%s: pending locks list is too small, " 871 "increase WITNESS_PENDLIST\n", 872 __func__); 873 } else 874 lock->lo_witness = enroll(type, class); 875 } 876 877 void 878 witness_destroy(struct lock_object *lock) 879 { 880 struct lock_class *class; 881 struct witness *w; 882 883 class = LOCK_CLASS(lock); 884 885 if (witness_cold) 886 panic("lock (%s) %s destroyed while witness_cold", 887 class->lc_name, lock->lo_name); 888 889 /* XXX: need to verify that no one holds the lock */ 890 if ((lock->lo_flags & LO_WITNESS) == 0 || lock->lo_witness == NULL) 891 return; 892 w = lock->lo_witness; 893 894 mtx_lock_spin(&w_mtx); 895 MPASS(w->w_refcount > 0); 896 w->w_refcount--; 897 898 if (w->w_refcount == 0) 899 depart(w); 900 mtx_unlock_spin(&w_mtx); 901 } 902 903 #ifdef DDB 904 static void 905 witness_ddb_compute_levels(void) 906 { 907 struct witness *w; 908 909 /* 910 * First clear all levels. 911 */ 912 STAILQ_FOREACH(w, &w_all, w_list) 913 w->w_ddb_level = -1; 914 915 /* 916 * Look for locks with no parents and level all their descendants. 917 */ 918 STAILQ_FOREACH(w, &w_all, w_list) { 919 920 /* If the witness has ancestors (is not a root), skip it. */ 921 if (w->w_num_ancestors > 0) 922 continue; 923 witness_ddb_level_descendants(w, 0); 924 } 925 } 926 927 static void 928 witness_ddb_level_descendants(struct witness *w, int l) 929 { 930 int i; 931 932 if (w->w_ddb_level >= l) 933 return; 934 935 w->w_ddb_level = l; 936 l++; 937 938 for (i = 1; i <= w_max_used_index; i++) { 939 if (w_rmatrix[w->w_index][i] & WITNESS_PARENT) 940 witness_ddb_level_descendants(&w_data[i], l); 941 } 942 } 943 944 static void 945 witness_ddb_display_descendants(int(*prnt)(const char *fmt, ...), 946 struct witness *w, int indent) 947 { 948 int i; 949 950 for (i = 0; i < indent; i++) 951 prnt(" "); 952 prnt("%s (type: %s, depth: %d, active refs: %d)", 953 w->w_name, w->w_class->lc_name, 954 w->w_ddb_level, w->w_refcount); 955 if (w->w_displayed) { 956 prnt(" -- (already displayed)\n"); 957 return; 958 } 959 w->w_displayed = 1; 960 if (w->w_file != NULL && w->w_line != 0) 961 prnt(" -- last acquired @ %s:%d\n", fixup_filename(w->w_file), 962 w->w_line); 963 else 964 prnt(" -- never acquired\n"); 965 indent++; 966 WITNESS_INDEX_ASSERT(w->w_index); 967 for (i = 1; i <= w_max_used_index; i++) { 968 if (db_pager_quit) 969 return; 970 if (w_rmatrix[w->w_index][i] & WITNESS_PARENT) 971 witness_ddb_display_descendants(prnt, &w_data[i], 972 indent); 973 } 974 } 975 976 static void 977 witness_ddb_display_list(int(*prnt)(const char *fmt, ...), 978 struct witness_list *list) 979 { 980 struct witness *w; 981 982 STAILQ_FOREACH(w, list, w_typelist) { 983 if (w->w_file == NULL || w->w_ddb_level > 0) 984 continue; 985 986 /* This lock has no anscestors - display its descendants. */ 987 witness_ddb_display_descendants(prnt, w, 0); 988 if (db_pager_quit) 989 return; 990 } 991 } 992 993 static void 994 witness_ddb_display(int(*prnt)(const char *fmt, ...)) 995 { 996 struct witness *w; 997 998 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); 999 witness_ddb_compute_levels(); 1000 1001 /* Clear all the displayed flags. */ 1002 STAILQ_FOREACH(w, &w_all, w_list) 1003 w->w_displayed = 0; 1004 1005 /* 1006 * First, handle sleep locks which have been acquired at least 1007 * once. 1008 */ 1009 prnt("Sleep locks:\n"); 1010 witness_ddb_display_list(prnt, &w_sleep); 1011 if (db_pager_quit) 1012 return; 1013 1014 /* 1015 * Now do spin locks which have been acquired at least once. 1016 */ 1017 prnt("\nSpin locks:\n"); 1018 witness_ddb_display_list(prnt, &w_spin); 1019 if (db_pager_quit) 1020 return; 1021 1022 /* 1023 * Finally, any locks which have not been acquired yet. 1024 */ 1025 prnt("\nLocks which were never acquired:\n"); 1026 STAILQ_FOREACH(w, &w_all, w_list) { 1027 if (w->w_file != NULL || w->w_refcount == 0) 1028 continue; 1029 prnt("%s (type: %s, depth: %d)\n", w->w_name, 1030 w->w_class->lc_name, w->w_ddb_level); 1031 if (db_pager_quit) 1032 return; 1033 } 1034 } 1035 #endif /* DDB */ 1036 1037 int 1038 witness_defineorder(struct lock_object *lock1, struct lock_object *lock2) 1039 { 1040 1041 if (witness_watch == -1 || panicstr != NULL) 1042 return (0); 1043 1044 /* Require locks that witness knows about. */ 1045 if (lock1 == NULL || lock1->lo_witness == NULL || lock2 == NULL || 1046 lock2->lo_witness == NULL) 1047 return (EINVAL); 1048 1049 mtx_assert(&w_mtx, MA_NOTOWNED); 1050 mtx_lock_spin(&w_mtx); 1051 1052 /* 1053 * If we already have either an explicit or implied lock order that 1054 * is the other way around, then return an error. 1055 */ 1056 if (witness_watch && 1057 isitmydescendant(lock2->lo_witness, lock1->lo_witness)) { 1058 mtx_unlock_spin(&w_mtx); 1059 return (EDOOFUS); 1060 } 1061 1062 /* Try to add the new order. */ 1063 CTR3(KTR_WITNESS, "%s: adding %s as a child of %s", __func__, 1064 lock2->lo_witness->w_name, lock1->lo_witness->w_name); 1065 itismychild(lock1->lo_witness, lock2->lo_witness); 1066 mtx_unlock_spin(&w_mtx); 1067 return (0); 1068 } 1069 1070 void 1071 witness_checkorder(struct lock_object *lock, int flags, const char *file, 1072 int line, struct lock_object *interlock) 1073 { 1074 struct lock_list_entry *lock_list, *lle; 1075 struct lock_instance *lock1, *lock2, *plock; 1076 struct lock_class *class, *iclass; 1077 struct witness *w, *w1; 1078 struct thread *td; 1079 int i, j; 1080 1081 if (witness_cold || witness_watch < 1 || lock->lo_witness == NULL || 1082 panicstr != NULL) 1083 return; 1084 1085 w = lock->lo_witness; 1086 class = LOCK_CLASS(lock); 1087 td = curthread; 1088 1089 if (class->lc_flags & LC_SLEEPLOCK) { 1090 1091 /* 1092 * Since spin locks include a critical section, this check 1093 * implicitly enforces a lock order of all sleep locks before 1094 * all spin locks. 1095 */ 1096 if (td->td_critnest != 0 && !kdb_active) 1097 kassert_panic("acquiring blockable sleep lock with " 1098 "spinlock or critical section held (%s) %s @ %s:%d", 1099 class->lc_name, lock->lo_name, 1100 fixup_filename(file), line); 1101 1102 /* 1103 * If this is the first lock acquired then just return as 1104 * no order checking is needed. 1105 */ 1106 lock_list = td->td_sleeplocks; 1107 if (lock_list == NULL || lock_list->ll_count == 0) 1108 return; 1109 } else { 1110 1111 /* 1112 * If this is the first lock, just return as no order 1113 * checking is needed. Avoid problems with thread 1114 * migration pinning the thread while checking if 1115 * spinlocks are held. If at least one spinlock is held 1116 * the thread is in a safe path and it is allowed to 1117 * unpin it. 1118 */ 1119 sched_pin(); 1120 lock_list = PCPU_GET(spinlocks); 1121 if (lock_list == NULL || lock_list->ll_count == 0) { 1122 sched_unpin(); 1123 return; 1124 } 1125 sched_unpin(); 1126 } 1127 1128 /* 1129 * Check to see if we are recursing on a lock we already own. If 1130 * so, make sure that we don't mismatch exclusive and shared lock 1131 * acquires. 1132 */ 1133 lock1 = find_instance(lock_list, lock); 1134 if (lock1 != NULL) { 1135 if ((lock1->li_flags & LI_EXCLUSIVE) != 0 && 1136 (flags & LOP_EXCLUSIVE) == 0) { 1137 witness_output("shared lock of (%s) %s @ %s:%d\n", 1138 class->lc_name, lock->lo_name, 1139 fixup_filename(file), line); 1140 witness_output("while exclusively locked from %s:%d\n", 1141 fixup_filename(lock1->li_file), lock1->li_line); 1142 kassert_panic("excl->share"); 1143 } 1144 if ((lock1->li_flags & LI_EXCLUSIVE) == 0 && 1145 (flags & LOP_EXCLUSIVE) != 0) { 1146 witness_output("exclusive lock of (%s) %s @ %s:%d\n", 1147 class->lc_name, lock->lo_name, 1148 fixup_filename(file), line); 1149 witness_output("while share locked from %s:%d\n", 1150 fixup_filename(lock1->li_file), lock1->li_line); 1151 kassert_panic("share->excl"); 1152 } 1153 return; 1154 } 1155 1156 /* Warn if the interlock is not locked exactly once. */ 1157 if (interlock != NULL) { 1158 iclass = LOCK_CLASS(interlock); 1159 lock1 = find_instance(lock_list, interlock); 1160 if (lock1 == NULL) 1161 kassert_panic("interlock (%s) %s not locked @ %s:%d", 1162 iclass->lc_name, interlock->lo_name, 1163 fixup_filename(file), line); 1164 else if ((lock1->li_flags & LI_RECURSEMASK) != 0) 1165 kassert_panic("interlock (%s) %s recursed @ %s:%d", 1166 iclass->lc_name, interlock->lo_name, 1167 fixup_filename(file), line); 1168 } 1169 1170 /* 1171 * Find the previously acquired lock, but ignore interlocks. 1172 */ 1173 plock = &lock_list->ll_children[lock_list->ll_count - 1]; 1174 if (interlock != NULL && plock->li_lock == interlock) { 1175 if (lock_list->ll_count > 1) 1176 plock = 1177 &lock_list->ll_children[lock_list->ll_count - 2]; 1178 else { 1179 lle = lock_list->ll_next; 1180 1181 /* 1182 * The interlock is the only lock we hold, so 1183 * simply return. 1184 */ 1185 if (lle == NULL) 1186 return; 1187 plock = &lle->ll_children[lle->ll_count - 1]; 1188 } 1189 } 1190 1191 /* 1192 * Try to perform most checks without a lock. If this succeeds we 1193 * can skip acquiring the lock and return success. Otherwise we redo 1194 * the check with the lock held to handle races with concurrent updates. 1195 */ 1196 w1 = plock->li_lock->lo_witness; 1197 if (witness_lock_order_check(w1, w)) 1198 return; 1199 1200 mtx_lock_spin(&w_mtx); 1201 if (witness_lock_order_check(w1, w)) { 1202 mtx_unlock_spin(&w_mtx); 1203 return; 1204 } 1205 witness_lock_order_add(w1, w); 1206 1207 /* 1208 * Check for duplicate locks of the same type. Note that we only 1209 * have to check for this on the last lock we just acquired. Any 1210 * other cases will be caught as lock order violations. 1211 */ 1212 if (w1 == w) { 1213 i = w->w_index; 1214 if (!(lock->lo_flags & LO_DUPOK) && !(flags & LOP_DUPOK) && 1215 !(w_rmatrix[i][i] & WITNESS_REVERSAL)) { 1216 w_rmatrix[i][i] |= WITNESS_REVERSAL; 1217 w->w_reversed = 1; 1218 mtx_unlock_spin(&w_mtx); 1219 witness_output( 1220 "acquiring duplicate lock of same type: \"%s\"\n", 1221 w->w_name); 1222 witness_output(" 1st %s @ %s:%d\n", plock->li_lock->lo_name, 1223 fixup_filename(plock->li_file), plock->li_line); 1224 witness_output(" 2nd %s @ %s:%d\n", lock->lo_name, 1225 fixup_filename(file), line); 1226 witness_debugger(1, __func__); 1227 } else 1228 mtx_unlock_spin(&w_mtx); 1229 return; 1230 } 1231 mtx_assert(&w_mtx, MA_OWNED); 1232 1233 /* 1234 * If we know that the lock we are acquiring comes after 1235 * the lock we most recently acquired in the lock order tree, 1236 * then there is no need for any further checks. 1237 */ 1238 if (isitmychild(w1, w)) 1239 goto out; 1240 1241 for (j = 0, lle = lock_list; lle != NULL; lle = lle->ll_next) { 1242 for (i = lle->ll_count - 1; i >= 0; i--, j++) { 1243 1244 MPASS(j < LOCK_CHILDCOUNT * LOCK_NCHILDREN); 1245 lock1 = &lle->ll_children[i]; 1246 1247 /* 1248 * Ignore the interlock. 1249 */ 1250 if (interlock == lock1->li_lock) 1251 continue; 1252 1253 /* 1254 * If this lock doesn't undergo witness checking, 1255 * then skip it. 1256 */ 1257 w1 = lock1->li_lock->lo_witness; 1258 if (w1 == NULL) { 1259 KASSERT((lock1->li_lock->lo_flags & LO_WITNESS) == 0, 1260 ("lock missing witness structure")); 1261 continue; 1262 } 1263 1264 /* 1265 * If we are locking Giant and this is a sleepable 1266 * lock, then skip it. 1267 */ 1268 if ((lock1->li_lock->lo_flags & LO_SLEEPABLE) != 0 && 1269 lock == &Giant.lock_object) 1270 continue; 1271 1272 /* 1273 * If we are locking a sleepable lock and this lock 1274 * is Giant, then skip it. 1275 */ 1276 if ((lock->lo_flags & LO_SLEEPABLE) != 0 && 1277 lock1->li_lock == &Giant.lock_object) 1278 continue; 1279 1280 /* 1281 * If we are locking a sleepable lock and this lock 1282 * isn't sleepable, we want to treat it as a lock 1283 * order violation to enfore a general lock order of 1284 * sleepable locks before non-sleepable locks. 1285 */ 1286 if (((lock->lo_flags & LO_SLEEPABLE) != 0 && 1287 (lock1->li_lock->lo_flags & LO_SLEEPABLE) == 0)) 1288 goto reversal; 1289 1290 /* 1291 * If we are locking Giant and this is a non-sleepable 1292 * lock, then treat it as a reversal. 1293 */ 1294 if ((lock1->li_lock->lo_flags & LO_SLEEPABLE) == 0 && 1295 lock == &Giant.lock_object) 1296 goto reversal; 1297 1298 /* 1299 * Check the lock order hierarchy for a reveresal. 1300 */ 1301 if (!isitmydescendant(w, w1)) 1302 continue; 1303 reversal: 1304 1305 /* 1306 * We have a lock order violation, check to see if it 1307 * is allowed or has already been yelled about. 1308 */ 1309 #ifdef BLESSING 1310 1311 /* 1312 * If the lock order is blessed, just bail. We don't 1313 * look for other lock order violations though, which 1314 * may be a bug. 1315 */ 1316 if (blessed(w, w1)) 1317 goto out; 1318 #endif 1319 1320 /* Bail if this violation is known */ 1321 if (w_rmatrix[w1->w_index][w->w_index] & WITNESS_REVERSAL) 1322 goto out; 1323 1324 /* Record this as a violation */ 1325 w_rmatrix[w1->w_index][w->w_index] |= WITNESS_REVERSAL; 1326 w_rmatrix[w->w_index][w1->w_index] |= WITNESS_REVERSAL; 1327 w->w_reversed = w1->w_reversed = 1; 1328 witness_increment_graph_generation(); 1329 mtx_unlock_spin(&w_mtx); 1330 1331 #ifdef WITNESS_NO_VNODE 1332 /* 1333 * There are known LORs between VNODE locks. They are 1334 * not an indication of a bug. VNODE locks are flagged 1335 * as such (LO_IS_VNODE) and we don't yell if the LOR 1336 * is between 2 VNODE locks. 1337 */ 1338 if ((lock->lo_flags & LO_IS_VNODE) != 0 && 1339 (lock1->li_lock->lo_flags & LO_IS_VNODE) != 0) 1340 return; 1341 #endif 1342 1343 /* 1344 * Ok, yell about it. 1345 */ 1346 if (((lock->lo_flags & LO_SLEEPABLE) != 0 && 1347 (lock1->li_lock->lo_flags & LO_SLEEPABLE) == 0)) 1348 witness_output( 1349 "lock order reversal: (sleepable after non-sleepable)\n"); 1350 else if ((lock1->li_lock->lo_flags & LO_SLEEPABLE) == 0 1351 && lock == &Giant.lock_object) 1352 witness_output( 1353 "lock order reversal: (Giant after non-sleepable)\n"); 1354 else 1355 witness_output("lock order reversal:\n"); 1356 1357 /* 1358 * Try to locate an earlier lock with 1359 * witness w in our list. 1360 */ 1361 do { 1362 lock2 = &lle->ll_children[i]; 1363 MPASS(lock2->li_lock != NULL); 1364 if (lock2->li_lock->lo_witness == w) 1365 break; 1366 if (i == 0 && lle->ll_next != NULL) { 1367 lle = lle->ll_next; 1368 i = lle->ll_count - 1; 1369 MPASS(i >= 0 && i < LOCK_NCHILDREN); 1370 } else 1371 i--; 1372 } while (i >= 0); 1373 if (i < 0) { 1374 witness_output(" 1st %p %s (%s) @ %s:%d\n", 1375 lock1->li_lock, lock1->li_lock->lo_name, 1376 w1->w_name, fixup_filename(lock1->li_file), 1377 lock1->li_line); 1378 witness_output(" 2nd %p %s (%s) @ %s:%d\n", lock, 1379 lock->lo_name, w->w_name, 1380 fixup_filename(file), line); 1381 } else { 1382 witness_output(" 1st %p %s (%s) @ %s:%d\n", 1383 lock2->li_lock, lock2->li_lock->lo_name, 1384 lock2->li_lock->lo_witness->w_name, 1385 fixup_filename(lock2->li_file), 1386 lock2->li_line); 1387 witness_output(" 2nd %p %s (%s) @ %s:%d\n", 1388 lock1->li_lock, lock1->li_lock->lo_name, 1389 w1->w_name, fixup_filename(lock1->li_file), 1390 lock1->li_line); 1391 witness_output(" 3rd %p %s (%s) @ %s:%d\n", lock, 1392 lock->lo_name, w->w_name, 1393 fixup_filename(file), line); 1394 } 1395 witness_debugger(1, __func__); 1396 return; 1397 } 1398 } 1399 1400 /* 1401 * If requested, build a new lock order. However, don't build a new 1402 * relationship between a sleepable lock and Giant if it is in the 1403 * wrong direction. The correct lock order is that sleepable locks 1404 * always come before Giant. 1405 */ 1406 if (flags & LOP_NEWORDER && 1407 !(plock->li_lock == &Giant.lock_object && 1408 (lock->lo_flags & LO_SLEEPABLE) != 0)) { 1409 CTR3(KTR_WITNESS, "%s: adding %s as a child of %s", __func__, 1410 w->w_name, plock->li_lock->lo_witness->w_name); 1411 itismychild(plock->li_lock->lo_witness, w); 1412 } 1413 out: 1414 mtx_unlock_spin(&w_mtx); 1415 } 1416 1417 void 1418 witness_lock(struct lock_object *lock, int flags, const char *file, int line) 1419 { 1420 struct lock_list_entry **lock_list, *lle; 1421 struct lock_instance *instance; 1422 struct witness *w; 1423 struct thread *td; 1424 1425 if (witness_cold || witness_watch == -1 || lock->lo_witness == NULL || 1426 panicstr != NULL) 1427 return; 1428 w = lock->lo_witness; 1429 td = curthread; 1430 1431 /* Determine lock list for this lock. */ 1432 if (LOCK_CLASS(lock)->lc_flags & LC_SLEEPLOCK) 1433 lock_list = &td->td_sleeplocks; 1434 else 1435 lock_list = PCPU_PTR(spinlocks); 1436 1437 /* Check to see if we are recursing on a lock we already own. */ 1438 instance = find_instance(*lock_list, lock); 1439 if (instance != NULL) { 1440 instance->li_flags++; 1441 CTR4(KTR_WITNESS, "%s: pid %d recursed on %s r=%d", __func__, 1442 td->td_proc->p_pid, lock->lo_name, 1443 instance->li_flags & LI_RECURSEMASK); 1444 instance->li_file = file; 1445 instance->li_line = line; 1446 return; 1447 } 1448 1449 /* Update per-witness last file and line acquire. */ 1450 w->w_file = file; 1451 w->w_line = line; 1452 1453 /* Find the next open lock instance in the list and fill it. */ 1454 lle = *lock_list; 1455 if (lle == NULL || lle->ll_count == LOCK_NCHILDREN) { 1456 lle = witness_lock_list_get(); 1457 if (lle == NULL) 1458 return; 1459 lle->ll_next = *lock_list; 1460 CTR3(KTR_WITNESS, "%s: pid %d added lle %p", __func__, 1461 td->td_proc->p_pid, lle); 1462 *lock_list = lle; 1463 } 1464 instance = &lle->ll_children[lle->ll_count++]; 1465 instance->li_lock = lock; 1466 instance->li_line = line; 1467 instance->li_file = file; 1468 if ((flags & LOP_EXCLUSIVE) != 0) 1469 instance->li_flags = LI_EXCLUSIVE; 1470 else 1471 instance->li_flags = 0; 1472 CTR4(KTR_WITNESS, "%s: pid %d added %s as lle[%d]", __func__, 1473 td->td_proc->p_pid, lock->lo_name, lle->ll_count - 1); 1474 } 1475 1476 void 1477 witness_upgrade(struct lock_object *lock, int flags, const char *file, int line) 1478 { 1479 struct lock_instance *instance; 1480 struct lock_class *class; 1481 1482 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); 1483 if (lock->lo_witness == NULL || witness_watch == -1 || panicstr != NULL) 1484 return; 1485 class = LOCK_CLASS(lock); 1486 if (witness_watch) { 1487 if ((lock->lo_flags & LO_UPGRADABLE) == 0) 1488 kassert_panic( 1489 "upgrade of non-upgradable lock (%s) %s @ %s:%d", 1490 class->lc_name, lock->lo_name, 1491 fixup_filename(file), line); 1492 if ((class->lc_flags & LC_SLEEPLOCK) == 0) 1493 kassert_panic( 1494 "upgrade of non-sleep lock (%s) %s @ %s:%d", 1495 class->lc_name, lock->lo_name, 1496 fixup_filename(file), line); 1497 } 1498 instance = find_instance(curthread->td_sleeplocks, lock); 1499 if (instance == NULL) { 1500 kassert_panic("upgrade of unlocked lock (%s) %s @ %s:%d", 1501 class->lc_name, lock->lo_name, 1502 fixup_filename(file), line); 1503 return; 1504 } 1505 if (witness_watch) { 1506 if ((instance->li_flags & LI_EXCLUSIVE) != 0) 1507 kassert_panic( 1508 "upgrade of exclusive lock (%s) %s @ %s:%d", 1509 class->lc_name, lock->lo_name, 1510 fixup_filename(file), line); 1511 if ((instance->li_flags & LI_RECURSEMASK) != 0) 1512 kassert_panic( 1513 "upgrade of recursed lock (%s) %s r=%d @ %s:%d", 1514 class->lc_name, lock->lo_name, 1515 instance->li_flags & LI_RECURSEMASK, 1516 fixup_filename(file), line); 1517 } 1518 instance->li_flags |= LI_EXCLUSIVE; 1519 } 1520 1521 void 1522 witness_downgrade(struct lock_object *lock, int flags, const char *file, 1523 int line) 1524 { 1525 struct lock_instance *instance; 1526 struct lock_class *class; 1527 1528 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); 1529 if (lock->lo_witness == NULL || witness_watch == -1 || panicstr != NULL) 1530 return; 1531 class = LOCK_CLASS(lock); 1532 if (witness_watch) { 1533 if ((lock->lo_flags & LO_UPGRADABLE) == 0) 1534 kassert_panic( 1535 "downgrade of non-upgradable lock (%s) %s @ %s:%d", 1536 class->lc_name, lock->lo_name, 1537 fixup_filename(file), line); 1538 if ((class->lc_flags & LC_SLEEPLOCK) == 0) 1539 kassert_panic( 1540 "downgrade of non-sleep lock (%s) %s @ %s:%d", 1541 class->lc_name, lock->lo_name, 1542 fixup_filename(file), line); 1543 } 1544 instance = find_instance(curthread->td_sleeplocks, lock); 1545 if (instance == NULL) { 1546 kassert_panic("downgrade of unlocked lock (%s) %s @ %s:%d", 1547 class->lc_name, lock->lo_name, 1548 fixup_filename(file), line); 1549 return; 1550 } 1551 if (witness_watch) { 1552 if ((instance->li_flags & LI_EXCLUSIVE) == 0) 1553 kassert_panic( 1554 "downgrade of shared lock (%s) %s @ %s:%d", 1555 class->lc_name, lock->lo_name, 1556 fixup_filename(file), line); 1557 if ((instance->li_flags & LI_RECURSEMASK) != 0) 1558 kassert_panic( 1559 "downgrade of recursed lock (%s) %s r=%d @ %s:%d", 1560 class->lc_name, lock->lo_name, 1561 instance->li_flags & LI_RECURSEMASK, 1562 fixup_filename(file), line); 1563 } 1564 instance->li_flags &= ~LI_EXCLUSIVE; 1565 } 1566 1567 void 1568 witness_unlock(struct lock_object *lock, int flags, const char *file, int line) 1569 { 1570 struct lock_list_entry **lock_list, *lle; 1571 struct lock_instance *instance; 1572 struct lock_class *class; 1573 struct thread *td; 1574 register_t s; 1575 int i, j; 1576 1577 if (witness_cold || lock->lo_witness == NULL || panicstr != NULL) 1578 return; 1579 td = curthread; 1580 class = LOCK_CLASS(lock); 1581 1582 /* Find lock instance associated with this lock. */ 1583 if (class->lc_flags & LC_SLEEPLOCK) 1584 lock_list = &td->td_sleeplocks; 1585 else 1586 lock_list = PCPU_PTR(spinlocks); 1587 lle = *lock_list; 1588 for (; *lock_list != NULL; lock_list = &(*lock_list)->ll_next) 1589 for (i = 0; i < (*lock_list)->ll_count; i++) { 1590 instance = &(*lock_list)->ll_children[i]; 1591 if (instance->li_lock == lock) 1592 goto found; 1593 } 1594 1595 /* 1596 * When disabling WITNESS through witness_watch we could end up in 1597 * having registered locks in the td_sleeplocks queue. 1598 * We have to make sure we flush these queues, so just search for 1599 * eventual register locks and remove them. 1600 */ 1601 if (witness_watch > 0) { 1602 kassert_panic("lock (%s) %s not locked @ %s:%d", class->lc_name, 1603 lock->lo_name, fixup_filename(file), line); 1604 return; 1605 } else { 1606 return; 1607 } 1608 found: 1609 1610 /* First, check for shared/exclusive mismatches. */ 1611 if ((instance->li_flags & LI_EXCLUSIVE) != 0 && witness_watch > 0 && 1612 (flags & LOP_EXCLUSIVE) == 0) { 1613 witness_output("shared unlock of (%s) %s @ %s:%d\n", 1614 class->lc_name, lock->lo_name, fixup_filename(file), line); 1615 witness_output("while exclusively locked from %s:%d\n", 1616 fixup_filename(instance->li_file), instance->li_line); 1617 kassert_panic("excl->ushare"); 1618 } 1619 if ((instance->li_flags & LI_EXCLUSIVE) == 0 && witness_watch > 0 && 1620 (flags & LOP_EXCLUSIVE) != 0) { 1621 witness_output("exclusive unlock of (%s) %s @ %s:%d\n", 1622 class->lc_name, lock->lo_name, fixup_filename(file), line); 1623 witness_output("while share locked from %s:%d\n", 1624 fixup_filename(instance->li_file), 1625 instance->li_line); 1626 kassert_panic("share->uexcl"); 1627 } 1628 /* If we are recursed, unrecurse. */ 1629 if ((instance->li_flags & LI_RECURSEMASK) > 0) { 1630 CTR4(KTR_WITNESS, "%s: pid %d unrecursed on %s r=%d", __func__, 1631 td->td_proc->p_pid, instance->li_lock->lo_name, 1632 instance->li_flags); 1633 instance->li_flags--; 1634 return; 1635 } 1636 /* The lock is now being dropped, check for NORELEASE flag */ 1637 if ((instance->li_flags & LI_NORELEASE) != 0 && witness_watch > 0) { 1638 witness_output("forbidden unlock of (%s) %s @ %s:%d\n", 1639 class->lc_name, lock->lo_name, fixup_filename(file), line); 1640 kassert_panic("lock marked norelease"); 1641 } 1642 1643 /* Otherwise, remove this item from the list. */ 1644 s = intr_disable(); 1645 CTR4(KTR_WITNESS, "%s: pid %d removed %s from lle[%d]", __func__, 1646 td->td_proc->p_pid, instance->li_lock->lo_name, 1647 (*lock_list)->ll_count - 1); 1648 for (j = i; j < (*lock_list)->ll_count - 1; j++) 1649 (*lock_list)->ll_children[j] = 1650 (*lock_list)->ll_children[j + 1]; 1651 (*lock_list)->ll_count--; 1652 intr_restore(s); 1653 1654 /* 1655 * In order to reduce contention on w_mtx, we want to keep always an 1656 * head object into lists so that frequent allocation from the 1657 * free witness pool (and subsequent locking) is avoided. 1658 * In order to maintain the current code simple, when the head 1659 * object is totally unloaded it means also that we do not have 1660 * further objects in the list, so the list ownership needs to be 1661 * hand over to another object if the current head needs to be freed. 1662 */ 1663 if ((*lock_list)->ll_count == 0) { 1664 if (*lock_list == lle) { 1665 if (lle->ll_next == NULL) 1666 return; 1667 } else 1668 lle = *lock_list; 1669 *lock_list = lle->ll_next; 1670 CTR3(KTR_WITNESS, "%s: pid %d removed lle %p", __func__, 1671 td->td_proc->p_pid, lle); 1672 witness_lock_list_free(lle); 1673 } 1674 } 1675 1676 void 1677 witness_thread_exit(struct thread *td) 1678 { 1679 struct lock_list_entry *lle; 1680 int i, n; 1681 1682 lle = td->td_sleeplocks; 1683 if (lle == NULL || panicstr != NULL) 1684 return; 1685 if (lle->ll_count != 0) { 1686 for (n = 0; lle != NULL; lle = lle->ll_next) 1687 for (i = lle->ll_count - 1; i >= 0; i--) { 1688 if (n == 0) 1689 witness_output( 1690 "Thread %p exiting with the following locks held:\n", td); 1691 n++; 1692 witness_list_lock(&lle->ll_children[i], 1693 witness_output); 1694 1695 } 1696 kassert_panic( 1697 "Thread %p cannot exit while holding sleeplocks\n", td); 1698 } 1699 witness_lock_list_free(lle); 1700 } 1701 1702 /* 1703 * Warn if any locks other than 'lock' are held. Flags can be passed in to 1704 * exempt Giant and sleepable locks from the checks as well. If any 1705 * non-exempt locks are held, then a supplied message is printed to the 1706 * output channel along with a list of the offending locks. If indicated in the 1707 * flags then a failure results in a panic as well. 1708 */ 1709 int 1710 witness_warn(int flags, struct lock_object *lock, const char *fmt, ...) 1711 { 1712 struct lock_list_entry *lock_list, *lle; 1713 struct lock_instance *lock1; 1714 struct thread *td; 1715 va_list ap; 1716 int i, n; 1717 1718 if (witness_cold || witness_watch < 1 || panicstr != NULL) 1719 return (0); 1720 n = 0; 1721 td = curthread; 1722 for (lle = td->td_sleeplocks; lle != NULL; lle = lle->ll_next) 1723 for (i = lle->ll_count - 1; i >= 0; i--) { 1724 lock1 = &lle->ll_children[i]; 1725 if (lock1->li_lock == lock) 1726 continue; 1727 if (flags & WARN_GIANTOK && 1728 lock1->li_lock == &Giant.lock_object) 1729 continue; 1730 if (flags & WARN_SLEEPOK && 1731 (lock1->li_lock->lo_flags & LO_SLEEPABLE) != 0) 1732 continue; 1733 if (n == 0) { 1734 va_start(ap, fmt); 1735 witness_voutput(fmt, ap); 1736 va_end(ap); 1737 witness_output( 1738 " with the following %slocks held:\n", 1739 (flags & WARN_SLEEPOK) != 0 ? 1740 "non-sleepable " : ""); 1741 } 1742 n++; 1743 witness_list_lock(lock1, witness_output); 1744 } 1745 1746 /* 1747 * Pin the thread in order to avoid problems with thread migration. 1748 * Once that all verifies are passed about spinlocks ownership, 1749 * the thread is in a safe path and it can be unpinned. 1750 */ 1751 sched_pin(); 1752 lock_list = PCPU_GET(spinlocks); 1753 if (lock_list != NULL && lock_list->ll_count != 0) { 1754 sched_unpin(); 1755 1756 /* 1757 * We should only have one spinlock and as long as 1758 * the flags cannot match for this locks class, 1759 * check if the first spinlock is the one curthread 1760 * should hold. 1761 */ 1762 lock1 = &lock_list->ll_children[lock_list->ll_count - 1]; 1763 if (lock_list->ll_count == 1 && lock_list->ll_next == NULL && 1764 lock1->li_lock == lock && n == 0) 1765 return (0); 1766 1767 va_start(ap, fmt); 1768 witness_voutput(fmt, ap); 1769 va_end(ap); 1770 witness_output(" with the following %slocks held:\n", 1771 (flags & WARN_SLEEPOK) != 0 ? "non-sleepable " : ""); 1772 n += witness_list_locks(&lock_list, witness_output); 1773 } else 1774 sched_unpin(); 1775 if (flags & WARN_PANIC && n) 1776 kassert_panic("%s", __func__); 1777 else 1778 witness_debugger(n, __func__); 1779 return (n); 1780 } 1781 1782 const char * 1783 witness_file(struct lock_object *lock) 1784 { 1785 struct witness *w; 1786 1787 if (witness_cold || witness_watch < 1 || lock->lo_witness == NULL) 1788 return ("?"); 1789 w = lock->lo_witness; 1790 return (w->w_file); 1791 } 1792 1793 int 1794 witness_line(struct lock_object *lock) 1795 { 1796 struct witness *w; 1797 1798 if (witness_cold || witness_watch < 1 || lock->lo_witness == NULL) 1799 return (0); 1800 w = lock->lo_witness; 1801 return (w->w_line); 1802 } 1803 1804 static struct witness * 1805 enroll(const char *description, struct lock_class *lock_class) 1806 { 1807 struct witness *w; 1808 struct witness_list *typelist; 1809 1810 MPASS(description != NULL); 1811 1812 if (witness_watch == -1 || panicstr != NULL) 1813 return (NULL); 1814 if ((lock_class->lc_flags & LC_SPINLOCK)) { 1815 if (witness_skipspin) 1816 return (NULL); 1817 else 1818 typelist = &w_spin; 1819 } else if ((lock_class->lc_flags & LC_SLEEPLOCK)) { 1820 typelist = &w_sleep; 1821 } else { 1822 kassert_panic("lock class %s is not sleep or spin", 1823 lock_class->lc_name); 1824 return (NULL); 1825 } 1826 1827 mtx_lock_spin(&w_mtx); 1828 w = witness_hash_get(description); 1829 if (w) 1830 goto found; 1831 if ((w = witness_get()) == NULL) 1832 return (NULL); 1833 MPASS(strlen(description) < MAX_W_NAME); 1834 strcpy(w->w_name, description); 1835 w->w_class = lock_class; 1836 w->w_refcount = 1; 1837 STAILQ_INSERT_HEAD(&w_all, w, w_list); 1838 if (lock_class->lc_flags & LC_SPINLOCK) { 1839 STAILQ_INSERT_HEAD(&w_spin, w, w_typelist); 1840 w_spin_cnt++; 1841 } else if (lock_class->lc_flags & LC_SLEEPLOCK) { 1842 STAILQ_INSERT_HEAD(&w_sleep, w, w_typelist); 1843 w_sleep_cnt++; 1844 } 1845 1846 /* Insert new witness into the hash */ 1847 witness_hash_put(w); 1848 witness_increment_graph_generation(); 1849 mtx_unlock_spin(&w_mtx); 1850 return (w); 1851 found: 1852 w->w_refcount++; 1853 mtx_unlock_spin(&w_mtx); 1854 if (lock_class != w->w_class) 1855 kassert_panic( 1856 "lock (%s) %s does not match earlier (%s) lock", 1857 description, lock_class->lc_name, 1858 w->w_class->lc_name); 1859 return (w); 1860 } 1861 1862 static void 1863 depart(struct witness *w) 1864 { 1865 struct witness_list *list; 1866 1867 MPASS(w->w_refcount == 0); 1868 if (w->w_class->lc_flags & LC_SLEEPLOCK) { 1869 list = &w_sleep; 1870 w_sleep_cnt--; 1871 } else { 1872 list = &w_spin; 1873 w_spin_cnt--; 1874 } 1875 /* 1876 * Set file to NULL as it may point into a loadable module. 1877 */ 1878 w->w_file = NULL; 1879 w->w_line = 0; 1880 witness_increment_graph_generation(); 1881 } 1882 1883 1884 static void 1885 adopt(struct witness *parent, struct witness *child) 1886 { 1887 int pi, ci, i, j; 1888 1889 if (witness_cold == 0) 1890 mtx_assert(&w_mtx, MA_OWNED); 1891 1892 /* If the relationship is already known, there's no work to be done. */ 1893 if (isitmychild(parent, child)) 1894 return; 1895 1896 /* When the structure of the graph changes, bump up the generation. */ 1897 witness_increment_graph_generation(); 1898 1899 /* 1900 * The hard part ... create the direct relationship, then propagate all 1901 * indirect relationships. 1902 */ 1903 pi = parent->w_index; 1904 ci = child->w_index; 1905 WITNESS_INDEX_ASSERT(pi); 1906 WITNESS_INDEX_ASSERT(ci); 1907 MPASS(pi != ci); 1908 w_rmatrix[pi][ci] |= WITNESS_PARENT; 1909 w_rmatrix[ci][pi] |= WITNESS_CHILD; 1910 1911 /* 1912 * If parent was not already an ancestor of child, 1913 * then we increment the descendant and ancestor counters. 1914 */ 1915 if ((w_rmatrix[pi][ci] & WITNESS_ANCESTOR) == 0) { 1916 parent->w_num_descendants++; 1917 child->w_num_ancestors++; 1918 } 1919 1920 /* 1921 * Find each ancestor of 'pi'. Note that 'pi' itself is counted as 1922 * an ancestor of 'pi' during this loop. 1923 */ 1924 for (i = 1; i <= w_max_used_index; i++) { 1925 if ((w_rmatrix[i][pi] & WITNESS_ANCESTOR_MASK) == 0 && 1926 (i != pi)) 1927 continue; 1928 1929 /* Find each descendant of 'i' and mark it as a descendant. */ 1930 for (j = 1; j <= w_max_used_index; j++) { 1931 1932 /* 1933 * Skip children that are already marked as 1934 * descendants of 'i'. 1935 */ 1936 if (w_rmatrix[i][j] & WITNESS_ANCESTOR_MASK) 1937 continue; 1938 1939 /* 1940 * We are only interested in descendants of 'ci'. Note 1941 * that 'ci' itself is counted as a descendant of 'ci'. 1942 */ 1943 if ((w_rmatrix[ci][j] & WITNESS_ANCESTOR_MASK) == 0 && 1944 (j != ci)) 1945 continue; 1946 w_rmatrix[i][j] |= WITNESS_ANCESTOR; 1947 w_rmatrix[j][i] |= WITNESS_DESCENDANT; 1948 w_data[i].w_num_descendants++; 1949 w_data[j].w_num_ancestors++; 1950 1951 /* 1952 * Make sure we aren't marking a node as both an 1953 * ancestor and descendant. We should have caught 1954 * this as a lock order reversal earlier. 1955 */ 1956 if ((w_rmatrix[i][j] & WITNESS_ANCESTOR_MASK) && 1957 (w_rmatrix[i][j] & WITNESS_DESCENDANT_MASK)) { 1958 printf("witness rmatrix paradox! [%d][%d]=%d " 1959 "both ancestor and descendant\n", 1960 i, j, w_rmatrix[i][j]); 1961 kdb_backtrace(); 1962 printf("Witness disabled.\n"); 1963 witness_watch = -1; 1964 } 1965 if ((w_rmatrix[j][i] & WITNESS_ANCESTOR_MASK) && 1966 (w_rmatrix[j][i] & WITNESS_DESCENDANT_MASK)) { 1967 printf("witness rmatrix paradox! [%d][%d]=%d " 1968 "both ancestor and descendant\n", 1969 j, i, w_rmatrix[j][i]); 1970 kdb_backtrace(); 1971 printf("Witness disabled.\n"); 1972 witness_watch = -1; 1973 } 1974 } 1975 } 1976 } 1977 1978 static void 1979 itismychild(struct witness *parent, struct witness *child) 1980 { 1981 int unlocked; 1982 1983 MPASS(child != NULL && parent != NULL); 1984 if (witness_cold == 0) 1985 mtx_assert(&w_mtx, MA_OWNED); 1986 1987 if (!witness_lock_type_equal(parent, child)) { 1988 if (witness_cold == 0) { 1989 unlocked = 1; 1990 mtx_unlock_spin(&w_mtx); 1991 } else { 1992 unlocked = 0; 1993 } 1994 kassert_panic( 1995 "%s: parent \"%s\" (%s) and child \"%s\" (%s) are not " 1996 "the same lock type", __func__, parent->w_name, 1997 parent->w_class->lc_name, child->w_name, 1998 child->w_class->lc_name); 1999 if (unlocked) 2000 mtx_lock_spin(&w_mtx); 2001 } 2002 adopt(parent, child); 2003 } 2004 2005 /* 2006 * Generic code for the isitmy*() functions. The rmask parameter is the 2007 * expected relationship of w1 to w2. 2008 */ 2009 static int 2010 _isitmyx(struct witness *w1, struct witness *w2, int rmask, const char *fname) 2011 { 2012 unsigned char r1, r2; 2013 int i1, i2; 2014 2015 i1 = w1->w_index; 2016 i2 = w2->w_index; 2017 WITNESS_INDEX_ASSERT(i1); 2018 WITNESS_INDEX_ASSERT(i2); 2019 r1 = w_rmatrix[i1][i2] & WITNESS_RELATED_MASK; 2020 r2 = w_rmatrix[i2][i1] & WITNESS_RELATED_MASK; 2021 2022 /* The flags on one better be the inverse of the flags on the other */ 2023 if (!((WITNESS_ATOD(r1) == r2 && WITNESS_DTOA(r2) == r1) || 2024 (WITNESS_DTOA(r1) == r2 && WITNESS_ATOD(r2) == r1))) { 2025 /* Don't squawk if we're potentially racing with an update. */ 2026 if (!mtx_owned(&w_mtx)) 2027 return (0); 2028 printf("%s: rmatrix mismatch between %s (index %d) and %s " 2029 "(index %d): w_rmatrix[%d][%d] == %hhx but " 2030 "w_rmatrix[%d][%d] == %hhx\n", 2031 fname, w1->w_name, i1, w2->w_name, i2, i1, i2, r1, 2032 i2, i1, r2); 2033 kdb_backtrace(); 2034 printf("Witness disabled.\n"); 2035 witness_watch = -1; 2036 } 2037 return (r1 & rmask); 2038 } 2039 2040 /* 2041 * Checks if @child is a direct child of @parent. 2042 */ 2043 static int 2044 isitmychild(struct witness *parent, struct witness *child) 2045 { 2046 2047 return (_isitmyx(parent, child, WITNESS_PARENT, __func__)); 2048 } 2049 2050 /* 2051 * Checks if @descendant is a direct or inderect descendant of @ancestor. 2052 */ 2053 static int 2054 isitmydescendant(struct witness *ancestor, struct witness *descendant) 2055 { 2056 2057 return (_isitmyx(ancestor, descendant, WITNESS_ANCESTOR_MASK, 2058 __func__)); 2059 } 2060 2061 #ifdef BLESSING 2062 static int 2063 blessed(struct witness *w1, struct witness *w2) 2064 { 2065 int i; 2066 struct witness_blessed *b; 2067 2068 for (i = 0; i < nitems(blessed_list); i++) { 2069 b = &blessed_list[i]; 2070 if (strcmp(w1->w_name, b->b_lock1) == 0) { 2071 if (strcmp(w2->w_name, b->b_lock2) == 0) 2072 return (1); 2073 continue; 2074 } 2075 if (strcmp(w1->w_name, b->b_lock2) == 0) 2076 if (strcmp(w2->w_name, b->b_lock1) == 0) 2077 return (1); 2078 } 2079 return (0); 2080 } 2081 #endif 2082 2083 static struct witness * 2084 witness_get(void) 2085 { 2086 struct witness *w; 2087 int index; 2088 2089 if (witness_cold == 0) 2090 mtx_assert(&w_mtx, MA_OWNED); 2091 2092 if (witness_watch == -1) { 2093 mtx_unlock_spin(&w_mtx); 2094 return (NULL); 2095 } 2096 if (STAILQ_EMPTY(&w_free)) { 2097 witness_watch = -1; 2098 mtx_unlock_spin(&w_mtx); 2099 printf("WITNESS: unable to allocate a new witness object\n"); 2100 return (NULL); 2101 } 2102 w = STAILQ_FIRST(&w_free); 2103 STAILQ_REMOVE_HEAD(&w_free, w_list); 2104 w_free_cnt--; 2105 index = w->w_index; 2106 MPASS(index > 0 && index == w_max_used_index+1 && 2107 index < witness_count); 2108 bzero(w, sizeof(*w)); 2109 w->w_index = index; 2110 if (index > w_max_used_index) 2111 w_max_used_index = index; 2112 return (w); 2113 } 2114 2115 static void 2116 witness_free(struct witness *w) 2117 { 2118 2119 STAILQ_INSERT_HEAD(&w_free, w, w_list); 2120 w_free_cnt++; 2121 } 2122 2123 static struct lock_list_entry * 2124 witness_lock_list_get(void) 2125 { 2126 struct lock_list_entry *lle; 2127 2128 if (witness_watch == -1) 2129 return (NULL); 2130 mtx_lock_spin(&w_mtx); 2131 lle = w_lock_list_free; 2132 if (lle == NULL) { 2133 witness_watch = -1; 2134 mtx_unlock_spin(&w_mtx); 2135 printf("%s: witness exhausted\n", __func__); 2136 return (NULL); 2137 } 2138 w_lock_list_free = lle->ll_next; 2139 mtx_unlock_spin(&w_mtx); 2140 bzero(lle, sizeof(*lle)); 2141 return (lle); 2142 } 2143 2144 static void 2145 witness_lock_list_free(struct lock_list_entry *lle) 2146 { 2147 2148 mtx_lock_spin(&w_mtx); 2149 lle->ll_next = w_lock_list_free; 2150 w_lock_list_free = lle; 2151 mtx_unlock_spin(&w_mtx); 2152 } 2153 2154 static struct lock_instance * 2155 find_instance(struct lock_list_entry *list, const struct lock_object *lock) 2156 { 2157 struct lock_list_entry *lle; 2158 struct lock_instance *instance; 2159 int i; 2160 2161 for (lle = list; lle != NULL; lle = lle->ll_next) 2162 for (i = lle->ll_count - 1; i >= 0; i--) { 2163 instance = &lle->ll_children[i]; 2164 if (instance->li_lock == lock) 2165 return (instance); 2166 } 2167 return (NULL); 2168 } 2169 2170 static void 2171 witness_list_lock(struct lock_instance *instance, 2172 int (*prnt)(const char *fmt, ...)) 2173 { 2174 struct lock_object *lock; 2175 2176 lock = instance->li_lock; 2177 prnt("%s %s %s", (instance->li_flags & LI_EXCLUSIVE) != 0 ? 2178 "exclusive" : "shared", LOCK_CLASS(lock)->lc_name, lock->lo_name); 2179 if (lock->lo_witness->w_name != lock->lo_name) 2180 prnt(" (%s)", lock->lo_witness->w_name); 2181 prnt(" r = %d (%p) locked @ %s:%d\n", 2182 instance->li_flags & LI_RECURSEMASK, lock, 2183 fixup_filename(instance->li_file), instance->li_line); 2184 } 2185 2186 static int 2187 witness_output(const char *fmt, ...) 2188 { 2189 va_list ap; 2190 int ret; 2191 2192 va_start(ap, fmt); 2193 ret = witness_voutput(fmt, ap); 2194 va_end(ap); 2195 return (ret); 2196 } 2197 2198 static int 2199 witness_voutput(const char *fmt, va_list ap) 2200 { 2201 int ret; 2202 2203 ret = 0; 2204 switch (witness_channel) { 2205 case WITNESS_CONSOLE: 2206 ret = vprintf(fmt, ap); 2207 break; 2208 case WITNESS_LOG: 2209 vlog(LOG_NOTICE, fmt, ap); 2210 break; 2211 case WITNESS_NONE: 2212 break; 2213 } 2214 return (ret); 2215 } 2216 2217 #ifdef DDB 2218 static int 2219 witness_thread_has_locks(struct thread *td) 2220 { 2221 2222 if (td->td_sleeplocks == NULL) 2223 return (0); 2224 return (td->td_sleeplocks->ll_count != 0); 2225 } 2226 2227 static int 2228 witness_proc_has_locks(struct proc *p) 2229 { 2230 struct thread *td; 2231 2232 FOREACH_THREAD_IN_PROC(p, td) { 2233 if (witness_thread_has_locks(td)) 2234 return (1); 2235 } 2236 return (0); 2237 } 2238 #endif 2239 2240 int 2241 witness_list_locks(struct lock_list_entry **lock_list, 2242 int (*prnt)(const char *fmt, ...)) 2243 { 2244 struct lock_list_entry *lle; 2245 int i, nheld; 2246 2247 nheld = 0; 2248 for (lle = *lock_list; lle != NULL; lle = lle->ll_next) 2249 for (i = lle->ll_count - 1; i >= 0; i--) { 2250 witness_list_lock(&lle->ll_children[i], prnt); 2251 nheld++; 2252 } 2253 return (nheld); 2254 } 2255 2256 /* 2257 * This is a bit risky at best. We call this function when we have timed 2258 * out acquiring a spin lock, and we assume that the other CPU is stuck 2259 * with this lock held. So, we go groveling around in the other CPU's 2260 * per-cpu data to try to find the lock instance for this spin lock to 2261 * see when it was last acquired. 2262 */ 2263 void 2264 witness_display_spinlock(struct lock_object *lock, struct thread *owner, 2265 int (*prnt)(const char *fmt, ...)) 2266 { 2267 struct lock_instance *instance; 2268 struct pcpu *pc; 2269 2270 if (owner->td_critnest == 0 || owner->td_oncpu == NOCPU) 2271 return; 2272 pc = pcpu_find(owner->td_oncpu); 2273 instance = find_instance(pc->pc_spinlocks, lock); 2274 if (instance != NULL) 2275 witness_list_lock(instance, prnt); 2276 } 2277 2278 void 2279 witness_save(struct lock_object *lock, const char **filep, int *linep) 2280 { 2281 struct lock_list_entry *lock_list; 2282 struct lock_instance *instance; 2283 struct lock_class *class; 2284 2285 /* 2286 * This function is used independently in locking code to deal with 2287 * Giant, SCHEDULER_STOPPED() check can be removed here after Giant 2288 * is gone. 2289 */ 2290 if (SCHEDULER_STOPPED()) 2291 return; 2292 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); 2293 if (lock->lo_witness == NULL || witness_watch == -1 || panicstr != NULL) 2294 return; 2295 class = LOCK_CLASS(lock); 2296 if (class->lc_flags & LC_SLEEPLOCK) 2297 lock_list = curthread->td_sleeplocks; 2298 else { 2299 if (witness_skipspin) 2300 return; 2301 lock_list = PCPU_GET(spinlocks); 2302 } 2303 instance = find_instance(lock_list, lock); 2304 if (instance == NULL) { 2305 kassert_panic("%s: lock (%s) %s not locked", __func__, 2306 class->lc_name, lock->lo_name); 2307 return; 2308 } 2309 *filep = instance->li_file; 2310 *linep = instance->li_line; 2311 } 2312 2313 void 2314 witness_restore(struct lock_object *lock, const char *file, int line) 2315 { 2316 struct lock_list_entry *lock_list; 2317 struct lock_instance *instance; 2318 struct lock_class *class; 2319 2320 /* 2321 * This function is used independently in locking code to deal with 2322 * Giant, SCHEDULER_STOPPED() check can be removed here after Giant 2323 * is gone. 2324 */ 2325 if (SCHEDULER_STOPPED()) 2326 return; 2327 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); 2328 if (lock->lo_witness == NULL || witness_watch == -1 || panicstr != NULL) 2329 return; 2330 class = LOCK_CLASS(lock); 2331 if (class->lc_flags & LC_SLEEPLOCK) 2332 lock_list = curthread->td_sleeplocks; 2333 else { 2334 if (witness_skipspin) 2335 return; 2336 lock_list = PCPU_GET(spinlocks); 2337 } 2338 instance = find_instance(lock_list, lock); 2339 if (instance == NULL) 2340 kassert_panic("%s: lock (%s) %s not locked", __func__, 2341 class->lc_name, lock->lo_name); 2342 lock->lo_witness->w_file = file; 2343 lock->lo_witness->w_line = line; 2344 if (instance == NULL) 2345 return; 2346 instance->li_file = file; 2347 instance->li_line = line; 2348 } 2349 2350 void 2351 witness_assert(const struct lock_object *lock, int flags, const char *file, 2352 int line) 2353 { 2354 #ifdef INVARIANT_SUPPORT 2355 struct lock_instance *instance; 2356 struct lock_class *class; 2357 2358 if (lock->lo_witness == NULL || witness_watch < 1 || panicstr != NULL) 2359 return; 2360 class = LOCK_CLASS(lock); 2361 if ((class->lc_flags & LC_SLEEPLOCK) != 0) 2362 instance = find_instance(curthread->td_sleeplocks, lock); 2363 else if ((class->lc_flags & LC_SPINLOCK) != 0) 2364 instance = find_instance(PCPU_GET(spinlocks), lock); 2365 else { 2366 kassert_panic("Lock (%s) %s is not sleep or spin!", 2367 class->lc_name, lock->lo_name); 2368 return; 2369 } 2370 switch (flags) { 2371 case LA_UNLOCKED: 2372 if (instance != NULL) 2373 kassert_panic("Lock (%s) %s locked @ %s:%d.", 2374 class->lc_name, lock->lo_name, 2375 fixup_filename(file), line); 2376 break; 2377 case LA_LOCKED: 2378 case LA_LOCKED | LA_RECURSED: 2379 case LA_LOCKED | LA_NOTRECURSED: 2380 case LA_SLOCKED: 2381 case LA_SLOCKED | LA_RECURSED: 2382 case LA_SLOCKED | LA_NOTRECURSED: 2383 case LA_XLOCKED: 2384 case LA_XLOCKED | LA_RECURSED: 2385 case LA_XLOCKED | LA_NOTRECURSED: 2386 if (instance == NULL) { 2387 kassert_panic("Lock (%s) %s not locked @ %s:%d.", 2388 class->lc_name, lock->lo_name, 2389 fixup_filename(file), line); 2390 break; 2391 } 2392 if ((flags & LA_XLOCKED) != 0 && 2393 (instance->li_flags & LI_EXCLUSIVE) == 0) 2394 kassert_panic( 2395 "Lock (%s) %s not exclusively locked @ %s:%d.", 2396 class->lc_name, lock->lo_name, 2397 fixup_filename(file), line); 2398 if ((flags & LA_SLOCKED) != 0 && 2399 (instance->li_flags & LI_EXCLUSIVE) != 0) 2400 kassert_panic( 2401 "Lock (%s) %s exclusively locked @ %s:%d.", 2402 class->lc_name, lock->lo_name, 2403 fixup_filename(file), line); 2404 if ((flags & LA_RECURSED) != 0 && 2405 (instance->li_flags & LI_RECURSEMASK) == 0) 2406 kassert_panic("Lock (%s) %s not recursed @ %s:%d.", 2407 class->lc_name, lock->lo_name, 2408 fixup_filename(file), line); 2409 if ((flags & LA_NOTRECURSED) != 0 && 2410 (instance->li_flags & LI_RECURSEMASK) != 0) 2411 kassert_panic("Lock (%s) %s recursed @ %s:%d.", 2412 class->lc_name, lock->lo_name, 2413 fixup_filename(file), line); 2414 break; 2415 default: 2416 kassert_panic("Invalid lock assertion at %s:%d.", 2417 fixup_filename(file), line); 2418 2419 } 2420 #endif /* INVARIANT_SUPPORT */ 2421 } 2422 2423 static void 2424 witness_setflag(struct lock_object *lock, int flag, int set) 2425 { 2426 struct lock_list_entry *lock_list; 2427 struct lock_instance *instance; 2428 struct lock_class *class; 2429 2430 if (lock->lo_witness == NULL || witness_watch == -1 || panicstr != NULL) 2431 return; 2432 class = LOCK_CLASS(lock); 2433 if (class->lc_flags & LC_SLEEPLOCK) 2434 lock_list = curthread->td_sleeplocks; 2435 else { 2436 if (witness_skipspin) 2437 return; 2438 lock_list = PCPU_GET(spinlocks); 2439 } 2440 instance = find_instance(lock_list, lock); 2441 if (instance == NULL) { 2442 kassert_panic("%s: lock (%s) %s not locked", __func__, 2443 class->lc_name, lock->lo_name); 2444 return; 2445 } 2446 2447 if (set) 2448 instance->li_flags |= flag; 2449 else 2450 instance->li_flags &= ~flag; 2451 } 2452 2453 void 2454 witness_norelease(struct lock_object *lock) 2455 { 2456 2457 witness_setflag(lock, LI_NORELEASE, 1); 2458 } 2459 2460 void 2461 witness_releaseok(struct lock_object *lock) 2462 { 2463 2464 witness_setflag(lock, LI_NORELEASE, 0); 2465 } 2466 2467 #ifdef DDB 2468 static void 2469 witness_ddb_list(struct thread *td) 2470 { 2471 2472 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); 2473 KASSERT(kdb_active, ("%s: not in the debugger", __func__)); 2474 2475 if (witness_watch < 1) 2476 return; 2477 2478 witness_list_locks(&td->td_sleeplocks, db_printf); 2479 2480 /* 2481 * We only handle spinlocks if td == curthread. This is somewhat broken 2482 * if td is currently executing on some other CPU and holds spin locks 2483 * as we won't display those locks. If we had a MI way of getting 2484 * the per-cpu data for a given cpu then we could use 2485 * td->td_oncpu to get the list of spinlocks for this thread 2486 * and "fix" this. 2487 * 2488 * That still wouldn't really fix this unless we locked the scheduler 2489 * lock or stopped the other CPU to make sure it wasn't changing the 2490 * list out from under us. It is probably best to just not try to 2491 * handle threads on other CPU's for now. 2492 */ 2493 if (td == curthread && PCPU_GET(spinlocks) != NULL) 2494 witness_list_locks(PCPU_PTR(spinlocks), db_printf); 2495 } 2496 2497 DB_SHOW_COMMAND(locks, db_witness_list) 2498 { 2499 struct thread *td; 2500 2501 if (have_addr) 2502 td = db_lookup_thread(addr, true); 2503 else 2504 td = kdb_thread; 2505 witness_ddb_list(td); 2506 } 2507 2508 DB_SHOW_ALL_COMMAND(locks, db_witness_list_all) 2509 { 2510 struct thread *td; 2511 struct proc *p; 2512 2513 /* 2514 * It would be nice to list only threads and processes that actually 2515 * held sleep locks, but that information is currently not exported 2516 * by WITNESS. 2517 */ 2518 FOREACH_PROC_IN_SYSTEM(p) { 2519 if (!witness_proc_has_locks(p)) 2520 continue; 2521 FOREACH_THREAD_IN_PROC(p, td) { 2522 if (!witness_thread_has_locks(td)) 2523 continue; 2524 db_printf("Process %d (%s) thread %p (%d)\n", p->p_pid, 2525 p->p_comm, td, td->td_tid); 2526 witness_ddb_list(td); 2527 if (db_pager_quit) 2528 return; 2529 } 2530 } 2531 } 2532 DB_SHOW_ALIAS(alllocks, db_witness_list_all) 2533 2534 DB_SHOW_COMMAND(witness, db_witness_display) 2535 { 2536 2537 witness_ddb_display(db_printf); 2538 } 2539 #endif 2540 2541 static int 2542 sysctl_debug_witness_badstacks(SYSCTL_HANDLER_ARGS) 2543 { 2544 struct witness_lock_order_data *data1, *data2, *tmp_data1, *tmp_data2; 2545 struct witness *tmp_w1, *tmp_w2, *w1, *w2; 2546 struct sbuf *sb; 2547 u_int w_rmatrix1, w_rmatrix2; 2548 int error, generation, i, j; 2549 2550 tmp_data1 = NULL; 2551 tmp_data2 = NULL; 2552 tmp_w1 = NULL; 2553 tmp_w2 = NULL; 2554 if (witness_watch < 1) { 2555 error = SYSCTL_OUT(req, w_notrunning, sizeof(w_notrunning)); 2556 return (error); 2557 } 2558 if (witness_cold) { 2559 error = SYSCTL_OUT(req, w_stillcold, sizeof(w_stillcold)); 2560 return (error); 2561 } 2562 error = 0; 2563 sb = sbuf_new(NULL, NULL, badstack_sbuf_size, SBUF_AUTOEXTEND); 2564 if (sb == NULL) 2565 return (ENOMEM); 2566 2567 /* Allocate and init temporary storage space. */ 2568 tmp_w1 = malloc(sizeof(struct witness), M_TEMP, M_WAITOK | M_ZERO); 2569 tmp_w2 = malloc(sizeof(struct witness), M_TEMP, M_WAITOK | M_ZERO); 2570 tmp_data1 = malloc(sizeof(struct witness_lock_order_data), M_TEMP, 2571 M_WAITOK | M_ZERO); 2572 tmp_data2 = malloc(sizeof(struct witness_lock_order_data), M_TEMP, 2573 M_WAITOK | M_ZERO); 2574 stack_zero(&tmp_data1->wlod_stack); 2575 stack_zero(&tmp_data2->wlod_stack); 2576 2577 restart: 2578 mtx_lock_spin(&w_mtx); 2579 generation = w_generation; 2580 mtx_unlock_spin(&w_mtx); 2581 sbuf_printf(sb, "Number of known direct relationships is %d\n", 2582 w_lohash.wloh_count); 2583 for (i = 1; i < w_max_used_index; i++) { 2584 mtx_lock_spin(&w_mtx); 2585 if (generation != w_generation) { 2586 mtx_unlock_spin(&w_mtx); 2587 2588 /* The graph has changed, try again. */ 2589 req->oldidx = 0; 2590 sbuf_clear(sb); 2591 goto restart; 2592 } 2593 2594 w1 = &w_data[i]; 2595 if (w1->w_reversed == 0) { 2596 mtx_unlock_spin(&w_mtx); 2597 continue; 2598 } 2599 2600 /* Copy w1 locally so we can release the spin lock. */ 2601 *tmp_w1 = *w1; 2602 mtx_unlock_spin(&w_mtx); 2603 2604 if (tmp_w1->w_reversed == 0) 2605 continue; 2606 for (j = 1; j < w_max_used_index; j++) { 2607 if ((w_rmatrix[i][j] & WITNESS_REVERSAL) == 0 || i > j) 2608 continue; 2609 2610 mtx_lock_spin(&w_mtx); 2611 if (generation != w_generation) { 2612 mtx_unlock_spin(&w_mtx); 2613 2614 /* The graph has changed, try again. */ 2615 req->oldidx = 0; 2616 sbuf_clear(sb); 2617 goto restart; 2618 } 2619 2620 w2 = &w_data[j]; 2621 data1 = witness_lock_order_get(w1, w2); 2622 data2 = witness_lock_order_get(w2, w1); 2623 2624 /* 2625 * Copy information locally so we can release the 2626 * spin lock. 2627 */ 2628 *tmp_w2 = *w2; 2629 w_rmatrix1 = (unsigned int)w_rmatrix[i][j]; 2630 w_rmatrix2 = (unsigned int)w_rmatrix[j][i]; 2631 2632 if (data1) { 2633 stack_zero(&tmp_data1->wlod_stack); 2634 stack_copy(&data1->wlod_stack, 2635 &tmp_data1->wlod_stack); 2636 } 2637 if (data2 && data2 != data1) { 2638 stack_zero(&tmp_data2->wlod_stack); 2639 stack_copy(&data2->wlod_stack, 2640 &tmp_data2->wlod_stack); 2641 } 2642 mtx_unlock_spin(&w_mtx); 2643 2644 sbuf_printf(sb, 2645 "\nLock order reversal between \"%s\"(%s) and \"%s\"(%s)!\n", 2646 tmp_w1->w_name, tmp_w1->w_class->lc_name, 2647 tmp_w2->w_name, tmp_w2->w_class->lc_name); 2648 if (data1) { 2649 sbuf_printf(sb, 2650 "Lock order \"%s\"(%s) -> \"%s\"(%s) first seen at:\n", 2651 tmp_w1->w_name, tmp_w1->w_class->lc_name, 2652 tmp_w2->w_name, tmp_w2->w_class->lc_name); 2653 stack_sbuf_print(sb, &tmp_data1->wlod_stack); 2654 sbuf_printf(sb, "\n"); 2655 } 2656 if (data2 && data2 != data1) { 2657 sbuf_printf(sb, 2658 "Lock order \"%s\"(%s) -> \"%s\"(%s) first seen at:\n", 2659 tmp_w2->w_name, tmp_w2->w_class->lc_name, 2660 tmp_w1->w_name, tmp_w1->w_class->lc_name); 2661 stack_sbuf_print(sb, &tmp_data2->wlod_stack); 2662 sbuf_printf(sb, "\n"); 2663 } 2664 } 2665 } 2666 mtx_lock_spin(&w_mtx); 2667 if (generation != w_generation) { 2668 mtx_unlock_spin(&w_mtx); 2669 2670 /* 2671 * The graph changed while we were printing stack data, 2672 * try again. 2673 */ 2674 req->oldidx = 0; 2675 sbuf_clear(sb); 2676 goto restart; 2677 } 2678 mtx_unlock_spin(&w_mtx); 2679 2680 /* Free temporary storage space. */ 2681 free(tmp_data1, M_TEMP); 2682 free(tmp_data2, M_TEMP); 2683 free(tmp_w1, M_TEMP); 2684 free(tmp_w2, M_TEMP); 2685 2686 sbuf_finish(sb); 2687 error = SYSCTL_OUT(req, sbuf_data(sb), sbuf_len(sb) + 1); 2688 sbuf_delete(sb); 2689 2690 return (error); 2691 } 2692 2693 static int 2694 sysctl_debug_witness_channel(SYSCTL_HANDLER_ARGS) 2695 { 2696 static const struct { 2697 enum witness_channel channel; 2698 const char *name; 2699 } channels[] = { 2700 { WITNESS_CONSOLE, "console" }, 2701 { WITNESS_LOG, "log" }, 2702 { WITNESS_NONE, "none" }, 2703 }; 2704 char buf[16]; 2705 u_int i; 2706 int error; 2707 2708 buf[0] = '\0'; 2709 for (i = 0; i < nitems(channels); i++) 2710 if (witness_channel == channels[i].channel) { 2711 snprintf(buf, sizeof(buf), "%s", channels[i].name); 2712 break; 2713 } 2714 2715 error = sysctl_handle_string(oidp, buf, sizeof(buf), req); 2716 if (error != 0 || req->newptr == NULL) 2717 return (error); 2718 2719 error = EINVAL; 2720 for (i = 0; i < nitems(channels); i++) 2721 if (strcmp(channels[i].name, buf) == 0) { 2722 witness_channel = channels[i].channel; 2723 error = 0; 2724 break; 2725 } 2726 return (error); 2727 } 2728 2729 static int 2730 sysctl_debug_witness_fullgraph(SYSCTL_HANDLER_ARGS) 2731 { 2732 struct witness *w; 2733 struct sbuf *sb; 2734 int error; 2735 2736 if (witness_watch < 1) { 2737 error = SYSCTL_OUT(req, w_notrunning, sizeof(w_notrunning)); 2738 return (error); 2739 } 2740 if (witness_cold) { 2741 error = SYSCTL_OUT(req, w_stillcold, sizeof(w_stillcold)); 2742 return (error); 2743 } 2744 error = 0; 2745 2746 error = sysctl_wire_old_buffer(req, 0); 2747 if (error != 0) 2748 return (error); 2749 sb = sbuf_new_for_sysctl(NULL, NULL, FULLGRAPH_SBUF_SIZE, req); 2750 if (sb == NULL) 2751 return (ENOMEM); 2752 sbuf_printf(sb, "\n"); 2753 2754 mtx_lock_spin(&w_mtx); 2755 STAILQ_FOREACH(w, &w_all, w_list) 2756 w->w_displayed = 0; 2757 STAILQ_FOREACH(w, &w_all, w_list) 2758 witness_add_fullgraph(sb, w); 2759 mtx_unlock_spin(&w_mtx); 2760 2761 /* 2762 * Close the sbuf and return to userland. 2763 */ 2764 error = sbuf_finish(sb); 2765 sbuf_delete(sb); 2766 2767 return (error); 2768 } 2769 2770 static int 2771 sysctl_debug_witness_watch(SYSCTL_HANDLER_ARGS) 2772 { 2773 int error, value; 2774 2775 value = witness_watch; 2776 error = sysctl_handle_int(oidp, &value, 0, req); 2777 if (error != 0 || req->newptr == NULL) 2778 return (error); 2779 if (value > 1 || value < -1 || 2780 (witness_watch == -1 && value != witness_watch)) 2781 return (EINVAL); 2782 witness_watch = value; 2783 return (0); 2784 } 2785 2786 static void 2787 witness_add_fullgraph(struct sbuf *sb, struct witness *w) 2788 { 2789 int i; 2790 2791 if (w->w_displayed != 0 || (w->w_file == NULL && w->w_line == 0)) 2792 return; 2793 w->w_displayed = 1; 2794 2795 WITNESS_INDEX_ASSERT(w->w_index); 2796 for (i = 1; i <= w_max_used_index; i++) { 2797 if (w_rmatrix[w->w_index][i] & WITNESS_PARENT) { 2798 sbuf_printf(sb, "\"%s\",\"%s\"\n", w->w_name, 2799 w_data[i].w_name); 2800 witness_add_fullgraph(sb, &w_data[i]); 2801 } 2802 } 2803 } 2804 2805 /* 2806 * A simple hash function. Takes a key pointer and a key size. If size == 0, 2807 * interprets the key as a string and reads until the null 2808 * terminator. Otherwise, reads the first size bytes. Returns an unsigned 32-bit 2809 * hash value computed from the key. 2810 */ 2811 static uint32_t 2812 witness_hash_djb2(const uint8_t *key, uint32_t size) 2813 { 2814 unsigned int hash = 5381; 2815 int i; 2816 2817 /* hash = hash * 33 + key[i] */ 2818 if (size) 2819 for (i = 0; i < size; i++) 2820 hash = ((hash << 5) + hash) + (unsigned int)key[i]; 2821 else 2822 for (i = 0; key[i] != 0; i++) 2823 hash = ((hash << 5) + hash) + (unsigned int)key[i]; 2824 2825 return (hash); 2826 } 2827 2828 2829 /* 2830 * Initializes the two witness hash tables. Called exactly once from 2831 * witness_initialize(). 2832 */ 2833 static void 2834 witness_init_hash_tables(void) 2835 { 2836 int i; 2837 2838 MPASS(witness_cold); 2839 2840 /* Initialize the hash tables. */ 2841 for (i = 0; i < WITNESS_HASH_SIZE; i++) 2842 w_hash.wh_array[i] = NULL; 2843 2844 w_hash.wh_size = WITNESS_HASH_SIZE; 2845 w_hash.wh_count = 0; 2846 2847 /* Initialize the lock order data hash. */ 2848 w_lofree = NULL; 2849 for (i = 0; i < WITNESS_LO_DATA_COUNT; i++) { 2850 memset(&w_lodata[i], 0, sizeof(w_lodata[i])); 2851 w_lodata[i].wlod_next = w_lofree; 2852 w_lofree = &w_lodata[i]; 2853 } 2854 w_lohash.wloh_size = WITNESS_LO_HASH_SIZE; 2855 w_lohash.wloh_count = 0; 2856 for (i = 0; i < WITNESS_LO_HASH_SIZE; i++) 2857 w_lohash.wloh_array[i] = NULL; 2858 } 2859 2860 static struct witness * 2861 witness_hash_get(const char *key) 2862 { 2863 struct witness *w; 2864 uint32_t hash; 2865 2866 MPASS(key != NULL); 2867 if (witness_cold == 0) 2868 mtx_assert(&w_mtx, MA_OWNED); 2869 hash = witness_hash_djb2(key, 0) % w_hash.wh_size; 2870 w = w_hash.wh_array[hash]; 2871 while (w != NULL) { 2872 if (strcmp(w->w_name, key) == 0) 2873 goto out; 2874 w = w->w_hash_next; 2875 } 2876 2877 out: 2878 return (w); 2879 } 2880 2881 static void 2882 witness_hash_put(struct witness *w) 2883 { 2884 uint32_t hash; 2885 2886 MPASS(w != NULL); 2887 MPASS(w->w_name != NULL); 2888 if (witness_cold == 0) 2889 mtx_assert(&w_mtx, MA_OWNED); 2890 KASSERT(witness_hash_get(w->w_name) == NULL, 2891 ("%s: trying to add a hash entry that already exists!", __func__)); 2892 KASSERT(w->w_hash_next == NULL, 2893 ("%s: w->w_hash_next != NULL", __func__)); 2894 2895 hash = witness_hash_djb2(w->w_name, 0) % w_hash.wh_size; 2896 w->w_hash_next = w_hash.wh_array[hash]; 2897 w_hash.wh_array[hash] = w; 2898 w_hash.wh_count++; 2899 } 2900 2901 2902 static struct witness_lock_order_data * 2903 witness_lock_order_get(struct witness *parent, struct witness *child) 2904 { 2905 struct witness_lock_order_data *data = NULL; 2906 struct witness_lock_order_key key; 2907 unsigned int hash; 2908 2909 MPASS(parent != NULL && child != NULL); 2910 key.from = parent->w_index; 2911 key.to = child->w_index; 2912 WITNESS_INDEX_ASSERT(key.from); 2913 WITNESS_INDEX_ASSERT(key.to); 2914 if ((w_rmatrix[parent->w_index][child->w_index] 2915 & WITNESS_LOCK_ORDER_KNOWN) == 0) 2916 goto out; 2917 2918 hash = witness_hash_djb2((const char*)&key, 2919 sizeof(key)) % w_lohash.wloh_size; 2920 data = w_lohash.wloh_array[hash]; 2921 while (data != NULL) { 2922 if (witness_lock_order_key_equal(&data->wlod_key, &key)) 2923 break; 2924 data = data->wlod_next; 2925 } 2926 2927 out: 2928 return (data); 2929 } 2930 2931 /* 2932 * Verify that parent and child have a known relationship, are not the same, 2933 * and child is actually a child of parent. This is done without w_mtx 2934 * to avoid contention in the common case. 2935 */ 2936 static int 2937 witness_lock_order_check(struct witness *parent, struct witness *child) 2938 { 2939 2940 if (parent != child && 2941 w_rmatrix[parent->w_index][child->w_index] 2942 & WITNESS_LOCK_ORDER_KNOWN && 2943 isitmychild(parent, child)) 2944 return (1); 2945 2946 return (0); 2947 } 2948 2949 static int 2950 witness_lock_order_add(struct witness *parent, struct witness *child) 2951 { 2952 struct witness_lock_order_data *data = NULL; 2953 struct witness_lock_order_key key; 2954 unsigned int hash; 2955 2956 MPASS(parent != NULL && child != NULL); 2957 key.from = parent->w_index; 2958 key.to = child->w_index; 2959 WITNESS_INDEX_ASSERT(key.from); 2960 WITNESS_INDEX_ASSERT(key.to); 2961 if (w_rmatrix[parent->w_index][child->w_index] 2962 & WITNESS_LOCK_ORDER_KNOWN) 2963 return (1); 2964 2965 hash = witness_hash_djb2((const char*)&key, 2966 sizeof(key)) % w_lohash.wloh_size; 2967 w_rmatrix[parent->w_index][child->w_index] |= WITNESS_LOCK_ORDER_KNOWN; 2968 data = w_lofree; 2969 if (data == NULL) 2970 return (0); 2971 w_lofree = data->wlod_next; 2972 data->wlod_next = w_lohash.wloh_array[hash]; 2973 data->wlod_key = key; 2974 w_lohash.wloh_array[hash] = data; 2975 w_lohash.wloh_count++; 2976 stack_zero(&data->wlod_stack); 2977 stack_save(&data->wlod_stack); 2978 return (1); 2979 } 2980 2981 /* Call this whenever the structure of the witness graph changes. */ 2982 static void 2983 witness_increment_graph_generation(void) 2984 { 2985 2986 if (witness_cold == 0) 2987 mtx_assert(&w_mtx, MA_OWNED); 2988 w_generation++; 2989 } 2990 2991 static int 2992 witness_output_drain(void *arg __unused, const char *data, int len) 2993 { 2994 2995 witness_output("%.*s", len, data); 2996 return (len); 2997 } 2998 2999 static void 3000 witness_debugger(int cond, const char *msg) 3001 { 3002 char buf[32]; 3003 struct sbuf sb; 3004 struct stack st; 3005 3006 if (!cond) 3007 return; 3008 3009 if (witness_trace) { 3010 sbuf_new(&sb, buf, sizeof(buf), SBUF_FIXEDLEN); 3011 sbuf_set_drain(&sb, witness_output_drain, NULL); 3012 3013 stack_zero(&st); 3014 stack_save(&st); 3015 witness_output("stack backtrace:\n"); 3016 stack_sbuf_print_ddb(&sb, &st); 3017 3018 sbuf_finish(&sb); 3019 } 3020 3021 #ifdef KDB 3022 if (witness_kdb) 3023 kdb_enter(KDB_WHY_WITNESS, msg); 3024 #endif 3025 } 3026