1 /*- 2 * Copyright (c) 2008 Isilon Systems, Inc. 3 * Copyright (c) 2008 Ilya Maykov <ivmaykov@gmail.com> 4 * Copyright (c) 1998 Berkeley Software Design, Inc. 5 * All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 3. Berkeley Software Design Inc's name may not be used to endorse or 16 * promote products derived from this software without specific prior 17 * written permission. 18 * 19 * THIS SOFTWARE IS PROVIDED BY BERKELEY SOFTWARE DESIGN INC ``AS IS'' AND 20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22 * ARE DISCLAIMED. IN NO EVENT SHALL BERKELEY SOFTWARE DESIGN INC BE LIABLE 23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29 * SUCH DAMAGE. 30 * 31 * from BSDI $Id: mutex_witness.c,v 1.1.2.20 2000/04/27 03:10:27 cp Exp $ 32 * and BSDI $Id: synch_machdep.c,v 2.3.2.39 2000/04/27 03:10:25 cp Exp $ 33 */ 34 35 /* 36 * Implementation of the `witness' lock verifier. Originally implemented for 37 * mutexes in BSD/OS. Extended to handle generic lock objects and lock 38 * classes in FreeBSD. 39 */ 40 41 /* 42 * Main Entry: witness 43 * Pronunciation: 'wit-n&s 44 * Function: noun 45 * Etymology: Middle English witnesse, from Old English witnes knowledge, 46 * testimony, witness, from 2wit 47 * Date: before 12th century 48 * 1 : attestation of a fact or event : TESTIMONY 49 * 2 : one that gives evidence; specifically : one who testifies in 50 * a cause or before a judicial tribunal 51 * 3 : one asked to be present at a transaction so as to be able to 52 * testify to its having taken place 53 * 4 : one who has personal knowledge of something 54 * 5 a : something serving as evidence or proof : SIGN 55 * b : public affirmation by word or example of usually 56 * religious faith or conviction <the heroic witness to divine 57 * life -- Pilot> 58 * 6 capitalized : a member of the Jehovah's Witnesses 59 */ 60 61 /* 62 * Special rules concerning Giant and lock orders: 63 * 64 * 1) Giant must be acquired before any other mutexes. Stated another way, 65 * no other mutex may be held when Giant is acquired. 66 * 67 * 2) Giant must be released when blocking on a sleepable lock. 68 * 69 * This rule is less obvious, but is a result of Giant providing the same 70 * semantics as spl(). Basically, when a thread sleeps, it must release 71 * Giant. When a thread blocks on a sleepable lock, it sleeps. Hence rule 72 * 2). 73 * 74 * 3) Giant may be acquired before or after sleepable locks. 75 * 76 * This rule is also not quite as obvious. Giant may be acquired after 77 * a sleepable lock because it is a non-sleepable lock and non-sleepable 78 * locks may always be acquired while holding a sleepable lock. The second 79 * case, Giant before a sleepable lock, follows from rule 2) above. Suppose 80 * you have two threads T1 and T2 and a sleepable lock X. Suppose that T1 81 * acquires X and blocks on Giant. Then suppose that T2 acquires Giant and 82 * blocks on X. When T2 blocks on X, T2 will release Giant allowing T1 to 83 * execute. Thus, acquiring Giant both before and after a sleepable lock 84 * will not result in a lock order reversal. 85 */ 86 87 #include <sys/cdefs.h> 88 __FBSDID("$FreeBSD$"); 89 90 #include "opt_ddb.h" 91 #include "opt_hwpmc_hooks.h" 92 #include "opt_stack.h" 93 #include "opt_witness.h" 94 95 #include <sys/param.h> 96 #include <sys/bus.h> 97 #include <sys/kdb.h> 98 #include <sys/kernel.h> 99 #include <sys/ktr.h> 100 #include <sys/lock.h> 101 #include <sys/malloc.h> 102 #include <sys/mutex.h> 103 #include <sys/priv.h> 104 #include <sys/proc.h> 105 #include <sys/sbuf.h> 106 #include <sys/sched.h> 107 #include <sys/stack.h> 108 #include <sys/sysctl.h> 109 #include <sys/syslog.h> 110 #include <sys/systm.h> 111 112 #ifdef DDB 113 #include <ddb/ddb.h> 114 #endif 115 116 #include <machine/stdarg.h> 117 118 #if !defined(DDB) && !defined(STACK) 119 #error "DDB or STACK options are required for WITNESS" 120 #endif 121 122 /* Note that these traces do not work with KTR_ALQ. */ 123 #if 0 124 #define KTR_WITNESS KTR_SUBSYS 125 #else 126 #define KTR_WITNESS 0 127 #endif 128 129 #define LI_RECURSEMASK 0x0000ffff /* Recursion depth of lock instance. */ 130 #define LI_EXCLUSIVE 0x00010000 /* Exclusive lock instance. */ 131 #define LI_NORELEASE 0x00020000 /* Lock not allowed to be released. */ 132 133 /* Define this to check for blessed mutexes */ 134 #undef BLESSING 135 136 #ifndef WITNESS_COUNT 137 #define WITNESS_COUNT 1536 138 #endif 139 #define WITNESS_HASH_SIZE 251 /* Prime, gives load factor < 2 */ 140 #define WITNESS_PENDLIST (1024 + MAXCPU) 141 142 /* Allocate 256 KB of stack data space */ 143 #define WITNESS_LO_DATA_COUNT 2048 144 145 /* Prime, gives load factor of ~2 at full load */ 146 #define WITNESS_LO_HASH_SIZE 1021 147 148 /* 149 * XXX: This is somewhat bogus, as we assume here that at most 2048 threads 150 * will hold LOCK_NCHILDREN locks. We handle failure ok, and we should 151 * probably be safe for the most part, but it's still a SWAG. 152 */ 153 #define LOCK_NCHILDREN 5 154 #define LOCK_CHILDCOUNT 2048 155 156 #define MAX_W_NAME 64 157 158 #define FULLGRAPH_SBUF_SIZE 512 159 160 /* 161 * These flags go in the witness relationship matrix and describe the 162 * relationship between any two struct witness objects. 163 */ 164 #define WITNESS_UNRELATED 0x00 /* No lock order relation. */ 165 #define WITNESS_PARENT 0x01 /* Parent, aka direct ancestor. */ 166 #define WITNESS_ANCESTOR 0x02 /* Direct or indirect ancestor. */ 167 #define WITNESS_CHILD 0x04 /* Child, aka direct descendant. */ 168 #define WITNESS_DESCENDANT 0x08 /* Direct or indirect descendant. */ 169 #define WITNESS_ANCESTOR_MASK (WITNESS_PARENT | WITNESS_ANCESTOR) 170 #define WITNESS_DESCENDANT_MASK (WITNESS_CHILD | WITNESS_DESCENDANT) 171 #define WITNESS_RELATED_MASK \ 172 (WITNESS_ANCESTOR_MASK | WITNESS_DESCENDANT_MASK) 173 #define WITNESS_REVERSAL 0x10 /* A lock order reversal has been 174 * observed. */ 175 #define WITNESS_RESERVED1 0x20 /* Unused flag, reserved. */ 176 #define WITNESS_RESERVED2 0x40 /* Unused flag, reserved. */ 177 #define WITNESS_LOCK_ORDER_KNOWN 0x80 /* This lock order is known. */ 178 179 /* Descendant to ancestor flags */ 180 #define WITNESS_DTOA(x) (((x) & WITNESS_RELATED_MASK) >> 2) 181 182 /* Ancestor to descendant flags */ 183 #define WITNESS_ATOD(x) (((x) & WITNESS_RELATED_MASK) << 2) 184 185 #define WITNESS_INDEX_ASSERT(i) \ 186 MPASS((i) > 0 && (i) <= w_max_used_index && (i) < witness_count) 187 188 static MALLOC_DEFINE(M_WITNESS, "Witness", "Witness"); 189 190 /* 191 * Lock instances. A lock instance is the data associated with a lock while 192 * it is held by witness. For example, a lock instance will hold the 193 * recursion count of a lock. Lock instances are held in lists. Spin locks 194 * are held in a per-cpu list while sleep locks are held in per-thread list. 195 */ 196 struct lock_instance { 197 struct lock_object *li_lock; 198 const char *li_file; 199 int li_line; 200 u_int li_flags; 201 }; 202 203 /* 204 * A simple list type used to build the list of locks held by a thread 205 * or CPU. We can't simply embed the list in struct lock_object since a 206 * lock may be held by more than one thread if it is a shared lock. Locks 207 * are added to the head of the list, so we fill up each list entry from 208 * "the back" logically. To ease some of the arithmetic, we actually fill 209 * in each list entry the normal way (children[0] then children[1], etc.) but 210 * when we traverse the list we read children[count-1] as the first entry 211 * down to children[0] as the final entry. 212 */ 213 struct lock_list_entry { 214 struct lock_list_entry *ll_next; 215 struct lock_instance ll_children[LOCK_NCHILDREN]; 216 u_int ll_count; 217 }; 218 219 /* 220 * The main witness structure. One of these per named lock type in the system 221 * (for example, "vnode interlock"). 222 */ 223 struct witness { 224 char w_name[MAX_W_NAME]; 225 uint32_t w_index; /* Index in the relationship matrix */ 226 struct lock_class *w_class; 227 STAILQ_ENTRY(witness) w_list; /* List of all witnesses. */ 228 STAILQ_ENTRY(witness) w_typelist; /* Witnesses of a type. */ 229 struct witness *w_hash_next; /* Linked list in hash buckets. */ 230 const char *w_file; /* File where last acquired */ 231 uint32_t w_line; /* Line where last acquired */ 232 uint32_t w_refcount; 233 uint16_t w_num_ancestors; /* direct/indirect 234 * ancestor count */ 235 uint16_t w_num_descendants; /* direct/indirect 236 * descendant count */ 237 int16_t w_ddb_level; 238 unsigned w_displayed:1; 239 unsigned w_reversed:1; 240 }; 241 242 STAILQ_HEAD(witness_list, witness); 243 244 /* 245 * The witness hash table. Keys are witness names (const char *), elements are 246 * witness objects (struct witness *). 247 */ 248 struct witness_hash { 249 struct witness *wh_array[WITNESS_HASH_SIZE]; 250 uint32_t wh_size; 251 uint32_t wh_count; 252 }; 253 254 /* 255 * Key type for the lock order data hash table. 256 */ 257 struct witness_lock_order_key { 258 uint16_t from; 259 uint16_t to; 260 }; 261 262 struct witness_lock_order_data { 263 struct stack wlod_stack; 264 struct witness_lock_order_key wlod_key; 265 struct witness_lock_order_data *wlod_next; 266 }; 267 268 /* 269 * The witness lock order data hash table. Keys are witness index tuples 270 * (struct witness_lock_order_key), elements are lock order data objects 271 * (struct witness_lock_order_data). 272 */ 273 struct witness_lock_order_hash { 274 struct witness_lock_order_data *wloh_array[WITNESS_LO_HASH_SIZE]; 275 u_int wloh_size; 276 u_int wloh_count; 277 }; 278 279 #ifdef BLESSING 280 struct witness_blessed { 281 const char *b_lock1; 282 const char *b_lock2; 283 }; 284 #endif 285 286 struct witness_pendhelp { 287 const char *wh_type; 288 struct lock_object *wh_lock; 289 }; 290 291 struct witness_order_list_entry { 292 const char *w_name; 293 struct lock_class *w_class; 294 }; 295 296 /* 297 * Returns 0 if one of the locks is a spin lock and the other is not. 298 * Returns 1 otherwise. 299 */ 300 static __inline int 301 witness_lock_type_equal(struct witness *w1, struct witness *w2) 302 { 303 304 return ((w1->w_class->lc_flags & (LC_SLEEPLOCK | LC_SPINLOCK)) == 305 (w2->w_class->lc_flags & (LC_SLEEPLOCK | LC_SPINLOCK))); 306 } 307 308 static __inline int 309 witness_lock_order_key_equal(const struct witness_lock_order_key *a, 310 const struct witness_lock_order_key *b) 311 { 312 313 return (a->from == b->from && a->to == b->to); 314 } 315 316 static int _isitmyx(struct witness *w1, struct witness *w2, int rmask, 317 const char *fname); 318 static void adopt(struct witness *parent, struct witness *child); 319 #ifdef BLESSING 320 static int blessed(struct witness *, struct witness *); 321 #endif 322 static void depart(struct witness *w); 323 static struct witness *enroll(const char *description, 324 struct lock_class *lock_class); 325 static struct lock_instance *find_instance(struct lock_list_entry *list, 326 const struct lock_object *lock); 327 static int isitmychild(struct witness *parent, struct witness *child); 328 static int isitmydescendant(struct witness *parent, struct witness *child); 329 static void itismychild(struct witness *parent, struct witness *child); 330 static int sysctl_debug_witness_badstacks(SYSCTL_HANDLER_ARGS); 331 static int sysctl_debug_witness_watch(SYSCTL_HANDLER_ARGS); 332 static int sysctl_debug_witness_fullgraph(SYSCTL_HANDLER_ARGS); 333 static int sysctl_debug_witness_channel(SYSCTL_HANDLER_ARGS); 334 static void witness_add_fullgraph(struct sbuf *sb, struct witness *parent); 335 #ifdef DDB 336 static void witness_ddb_compute_levels(void); 337 static void witness_ddb_display(int(*)(const char *fmt, ...)); 338 static void witness_ddb_display_descendants(int(*)(const char *fmt, ...), 339 struct witness *, int indent); 340 static void witness_ddb_display_list(int(*prnt)(const char *fmt, ...), 341 struct witness_list *list); 342 static void witness_ddb_level_descendants(struct witness *parent, int l); 343 static void witness_ddb_list(struct thread *td); 344 #endif 345 static void witness_debugger(int cond, const char *msg); 346 static void witness_free(struct witness *m); 347 static struct witness *witness_get(void); 348 static uint32_t witness_hash_djb2(const uint8_t *key, uint32_t size); 349 static struct witness *witness_hash_get(const char *key); 350 static void witness_hash_put(struct witness *w); 351 static void witness_init_hash_tables(void); 352 static void witness_increment_graph_generation(void); 353 static void witness_lock_list_free(struct lock_list_entry *lle); 354 static struct lock_list_entry *witness_lock_list_get(void); 355 static int witness_lock_order_add(struct witness *parent, 356 struct witness *child); 357 static int witness_lock_order_check(struct witness *parent, 358 struct witness *child); 359 static struct witness_lock_order_data *witness_lock_order_get( 360 struct witness *parent, 361 struct witness *child); 362 static void witness_list_lock(struct lock_instance *instance, 363 int (*prnt)(const char *fmt, ...)); 364 static int witness_output(const char *fmt, ...) __printflike(1, 2); 365 static int witness_voutput(const char *fmt, va_list ap) __printflike(1, 0); 366 static void witness_setflag(struct lock_object *lock, int flag, int set); 367 368 static SYSCTL_NODE(_debug, OID_AUTO, witness, CTLFLAG_RW, NULL, 369 "Witness Locking"); 370 371 /* 372 * If set to 0, lock order checking is disabled. If set to -1, 373 * witness is completely disabled. Otherwise witness performs full 374 * lock order checking for all locks. At runtime, lock order checking 375 * may be toggled. However, witness cannot be reenabled once it is 376 * completely disabled. 377 */ 378 static int witness_watch = 1; 379 SYSCTL_PROC(_debug_witness, OID_AUTO, watch, CTLFLAG_RWTUN | CTLTYPE_INT, NULL, 0, 380 sysctl_debug_witness_watch, "I", "witness is watching lock operations"); 381 382 #ifdef KDB 383 /* 384 * When KDB is enabled and witness_kdb is 1, it will cause the system 385 * to drop into kdebug() when: 386 * - a lock hierarchy violation occurs 387 * - locks are held when going to sleep. 388 */ 389 #ifdef WITNESS_KDB 390 int witness_kdb = 1; 391 #else 392 int witness_kdb = 0; 393 #endif 394 SYSCTL_INT(_debug_witness, OID_AUTO, kdb, CTLFLAG_RWTUN, &witness_kdb, 0, ""); 395 #endif /* KDB */ 396 397 #if defined(DDB) || defined(KDB) 398 /* 399 * When DDB or KDB is enabled and witness_trace is 1, it will cause the system 400 * to print a stack trace: 401 * - a lock hierarchy violation occurs 402 * - locks are held when going to sleep. 403 */ 404 int witness_trace = 1; 405 SYSCTL_INT(_debug_witness, OID_AUTO, trace, CTLFLAG_RWTUN, &witness_trace, 0, ""); 406 #endif /* DDB || KDB */ 407 408 #ifdef WITNESS_SKIPSPIN 409 int witness_skipspin = 1; 410 #else 411 int witness_skipspin = 0; 412 #endif 413 SYSCTL_INT(_debug_witness, OID_AUTO, skipspin, CTLFLAG_RDTUN, &witness_skipspin, 0, ""); 414 415 int badstack_sbuf_size; 416 417 int witness_count = WITNESS_COUNT; 418 SYSCTL_INT(_debug_witness, OID_AUTO, witness_count, CTLFLAG_RDTUN, 419 &witness_count, 0, ""); 420 421 /* 422 * Output channel for witness messages. By default we print to the console. 423 */ 424 enum witness_channel { 425 WITNESS_CONSOLE, 426 WITNESS_LOG, 427 WITNESS_NONE, 428 }; 429 430 static enum witness_channel witness_channel = WITNESS_CONSOLE; 431 SYSCTL_PROC(_debug_witness, OID_AUTO, output_channel, CTLTYPE_STRING | 432 CTLFLAG_RWTUN, NULL, 0, sysctl_debug_witness_channel, "A", 433 "Output channel for warnings"); 434 435 /* 436 * Call this to print out the relations between locks. 437 */ 438 SYSCTL_PROC(_debug_witness, OID_AUTO, fullgraph, CTLTYPE_STRING | CTLFLAG_RD, 439 NULL, 0, sysctl_debug_witness_fullgraph, "A", "Show locks relation graphs"); 440 441 /* 442 * Call this to print out the witness faulty stacks. 443 */ 444 SYSCTL_PROC(_debug_witness, OID_AUTO, badstacks, CTLTYPE_STRING | CTLFLAG_RD, 445 NULL, 0, sysctl_debug_witness_badstacks, "A", "Show bad witness stacks"); 446 447 static struct mtx w_mtx; 448 449 /* w_list */ 450 static struct witness_list w_free = STAILQ_HEAD_INITIALIZER(w_free); 451 static struct witness_list w_all = STAILQ_HEAD_INITIALIZER(w_all); 452 453 /* w_typelist */ 454 static struct witness_list w_spin = STAILQ_HEAD_INITIALIZER(w_spin); 455 static struct witness_list w_sleep = STAILQ_HEAD_INITIALIZER(w_sleep); 456 457 /* lock list */ 458 static struct lock_list_entry *w_lock_list_free = NULL; 459 static struct witness_pendhelp pending_locks[WITNESS_PENDLIST]; 460 static u_int pending_cnt; 461 462 static int w_free_cnt, w_spin_cnt, w_sleep_cnt; 463 SYSCTL_INT(_debug_witness, OID_AUTO, free_cnt, CTLFLAG_RD, &w_free_cnt, 0, ""); 464 SYSCTL_INT(_debug_witness, OID_AUTO, spin_cnt, CTLFLAG_RD, &w_spin_cnt, 0, ""); 465 SYSCTL_INT(_debug_witness, OID_AUTO, sleep_cnt, CTLFLAG_RD, &w_sleep_cnt, 0, 466 ""); 467 468 static struct witness *w_data; 469 static uint8_t **w_rmatrix; 470 static struct lock_list_entry w_locklistdata[LOCK_CHILDCOUNT]; 471 static struct witness_hash w_hash; /* The witness hash table. */ 472 473 /* The lock order data hash */ 474 static struct witness_lock_order_data w_lodata[WITNESS_LO_DATA_COUNT]; 475 static struct witness_lock_order_data *w_lofree = NULL; 476 static struct witness_lock_order_hash w_lohash; 477 static int w_max_used_index = 0; 478 static unsigned int w_generation = 0; 479 static const char w_notrunning[] = "Witness not running\n"; 480 static const char w_stillcold[] = "Witness is still cold\n"; 481 482 483 static struct witness_order_list_entry order_lists[] = { 484 /* 485 * sx locks 486 */ 487 { "proctree", &lock_class_sx }, 488 { "allproc", &lock_class_sx }, 489 { "allprison", &lock_class_sx }, 490 { NULL, NULL }, 491 /* 492 * Various mutexes 493 */ 494 { "Giant", &lock_class_mtx_sleep }, 495 { "pipe mutex", &lock_class_mtx_sleep }, 496 { "sigio lock", &lock_class_mtx_sleep }, 497 { "process group", &lock_class_mtx_sleep }, 498 { "process lock", &lock_class_mtx_sleep }, 499 { "session", &lock_class_mtx_sleep }, 500 { "uidinfo hash", &lock_class_rw }, 501 #ifdef HWPMC_HOOKS 502 { "pmc-sleep", &lock_class_mtx_sleep }, 503 #endif 504 { "time lock", &lock_class_mtx_sleep }, 505 { NULL, NULL }, 506 /* 507 * umtx 508 */ 509 { "umtx lock", &lock_class_mtx_sleep }, 510 { NULL, NULL }, 511 /* 512 * Sockets 513 */ 514 { "accept", &lock_class_mtx_sleep }, 515 { "so_snd", &lock_class_mtx_sleep }, 516 { "so_rcv", &lock_class_mtx_sleep }, 517 { "sellck", &lock_class_mtx_sleep }, 518 { NULL, NULL }, 519 /* 520 * Routing 521 */ 522 { "so_rcv", &lock_class_mtx_sleep }, 523 { "radix node head", &lock_class_rw }, 524 { "rtentry", &lock_class_mtx_sleep }, 525 { "ifaddr", &lock_class_mtx_sleep }, 526 { NULL, NULL }, 527 /* 528 * IPv4 multicast: 529 * protocol locks before interface locks, after UDP locks. 530 */ 531 { "udpinp", &lock_class_rw }, 532 { "in_multi_mtx", &lock_class_mtx_sleep }, 533 { "igmp_mtx", &lock_class_mtx_sleep }, 534 { "if_addr_lock", &lock_class_rw }, 535 { NULL, NULL }, 536 /* 537 * IPv6 multicast: 538 * protocol locks before interface locks, after UDP locks. 539 */ 540 { "udpinp", &lock_class_rw }, 541 { "in6_multi_mtx", &lock_class_mtx_sleep }, 542 { "mld_mtx", &lock_class_mtx_sleep }, 543 { "if_addr_lock", &lock_class_rw }, 544 { NULL, NULL }, 545 /* 546 * UNIX Domain Sockets 547 */ 548 { "unp_link_rwlock", &lock_class_rw }, 549 { "unp_list_lock", &lock_class_mtx_sleep }, 550 { "unp", &lock_class_mtx_sleep }, 551 { "so_snd", &lock_class_mtx_sleep }, 552 { NULL, NULL }, 553 /* 554 * UDP/IP 555 */ 556 { "udp", &lock_class_rw }, 557 { "udpinp", &lock_class_rw }, 558 { "so_snd", &lock_class_mtx_sleep }, 559 { NULL, NULL }, 560 /* 561 * TCP/IP 562 */ 563 { "tcp", &lock_class_rw }, 564 { "tcpinp", &lock_class_rw }, 565 { "so_snd", &lock_class_mtx_sleep }, 566 { NULL, NULL }, 567 /* 568 * BPF 569 */ 570 { "bpf global lock", &lock_class_mtx_sleep }, 571 { "bpf interface lock", &lock_class_rw }, 572 { "bpf cdev lock", &lock_class_mtx_sleep }, 573 { NULL, NULL }, 574 /* 575 * NFS server 576 */ 577 { "nfsd_mtx", &lock_class_mtx_sleep }, 578 { "so_snd", &lock_class_mtx_sleep }, 579 { NULL, NULL }, 580 581 /* 582 * IEEE 802.11 583 */ 584 { "802.11 com lock", &lock_class_mtx_sleep}, 585 { NULL, NULL }, 586 /* 587 * Network drivers 588 */ 589 { "network driver", &lock_class_mtx_sleep}, 590 { NULL, NULL }, 591 592 /* 593 * Netgraph 594 */ 595 { "ng_node", &lock_class_mtx_sleep }, 596 { "ng_worklist", &lock_class_mtx_sleep }, 597 { NULL, NULL }, 598 /* 599 * CDEV 600 */ 601 { "vm map (system)", &lock_class_mtx_sleep }, 602 { "vm page queue", &lock_class_mtx_sleep }, 603 { "vnode interlock", &lock_class_mtx_sleep }, 604 { "cdev", &lock_class_mtx_sleep }, 605 { NULL, NULL }, 606 /* 607 * VM 608 */ 609 { "vm map (user)", &lock_class_sx }, 610 { "vm object", &lock_class_rw }, 611 { "vm page", &lock_class_mtx_sleep }, 612 { "vm page queue", &lock_class_mtx_sleep }, 613 { "pmap pv global", &lock_class_rw }, 614 { "pmap", &lock_class_mtx_sleep }, 615 { "pmap pv list", &lock_class_rw }, 616 { "vm page free queue", &lock_class_mtx_sleep }, 617 { NULL, NULL }, 618 /* 619 * kqueue/VFS interaction 620 */ 621 { "kqueue", &lock_class_mtx_sleep }, 622 { "struct mount mtx", &lock_class_mtx_sleep }, 623 { "vnode interlock", &lock_class_mtx_sleep }, 624 { NULL, NULL }, 625 /* 626 * ZFS locking 627 */ 628 { "dn->dn_mtx", &lock_class_sx }, 629 { "dr->dt.di.dr_mtx", &lock_class_sx }, 630 { "db->db_mtx", &lock_class_sx }, 631 { NULL, NULL }, 632 /* 633 * spin locks 634 */ 635 #ifdef SMP 636 { "ap boot", &lock_class_mtx_spin }, 637 #endif 638 { "rm.mutex_mtx", &lock_class_mtx_spin }, 639 { "sio", &lock_class_mtx_spin }, 640 { "scrlock", &lock_class_mtx_spin }, 641 #ifdef __i386__ 642 { "cy", &lock_class_mtx_spin }, 643 #endif 644 #ifdef __sparc64__ 645 { "pcib_mtx", &lock_class_mtx_spin }, 646 { "rtc_mtx", &lock_class_mtx_spin }, 647 #endif 648 { "scc_hwmtx", &lock_class_mtx_spin }, 649 { "uart_hwmtx", &lock_class_mtx_spin }, 650 { "fast_taskqueue", &lock_class_mtx_spin }, 651 { "intr table", &lock_class_mtx_spin }, 652 #ifdef HWPMC_HOOKS 653 { "pmc-per-proc", &lock_class_mtx_spin }, 654 #endif 655 { "process slock", &lock_class_mtx_spin }, 656 { "sleepq chain", &lock_class_mtx_spin }, 657 { "rm_spinlock", &lock_class_mtx_spin }, 658 { "turnstile chain", &lock_class_mtx_spin }, 659 { "turnstile lock", &lock_class_mtx_spin }, 660 { "sched lock", &lock_class_mtx_spin }, 661 { "td_contested", &lock_class_mtx_spin }, 662 { "callout", &lock_class_mtx_spin }, 663 { "entropy harvest mutex", &lock_class_mtx_spin }, 664 { "syscons video lock", &lock_class_mtx_spin }, 665 #ifdef SMP 666 { "smp rendezvous", &lock_class_mtx_spin }, 667 #endif 668 #ifdef __powerpc__ 669 { "tlb0", &lock_class_mtx_spin }, 670 #endif 671 /* 672 * leaf locks 673 */ 674 { "intrcnt", &lock_class_mtx_spin }, 675 { "icu", &lock_class_mtx_spin }, 676 #if defined(SMP) && defined(__sparc64__) 677 { "ipi", &lock_class_mtx_spin }, 678 #endif 679 #ifdef __i386__ 680 { "allpmaps", &lock_class_mtx_spin }, 681 { "descriptor tables", &lock_class_mtx_spin }, 682 #endif 683 { "clk", &lock_class_mtx_spin }, 684 { "cpuset", &lock_class_mtx_spin }, 685 { "mprof lock", &lock_class_mtx_spin }, 686 { "zombie lock", &lock_class_mtx_spin }, 687 { "ALD Queue", &lock_class_mtx_spin }, 688 #if defined(__i386__) || defined(__amd64__) 689 { "pcicfg", &lock_class_mtx_spin }, 690 { "NDIS thread lock", &lock_class_mtx_spin }, 691 #endif 692 { "tw_osl_io_lock", &lock_class_mtx_spin }, 693 { "tw_osl_q_lock", &lock_class_mtx_spin }, 694 { "tw_cl_io_lock", &lock_class_mtx_spin }, 695 { "tw_cl_intr_lock", &lock_class_mtx_spin }, 696 { "tw_cl_gen_lock", &lock_class_mtx_spin }, 697 #ifdef HWPMC_HOOKS 698 { "pmc-leaf", &lock_class_mtx_spin }, 699 #endif 700 { "blocked lock", &lock_class_mtx_spin }, 701 { NULL, NULL }, 702 { NULL, NULL } 703 }; 704 705 #ifdef BLESSING 706 /* 707 * Pairs of locks which have been blessed 708 * Don't complain about order problems with blessed locks 709 */ 710 static struct witness_blessed blessed_list[] = { 711 }; 712 static int blessed_count = nitems(blessed_list); 713 #endif 714 715 /* 716 * This global is set to 0 once it becomes safe to use the witness code. 717 */ 718 static int witness_cold = 1; 719 720 /* 721 * This global is set to 1 once the static lock orders have been enrolled 722 * so that a warning can be issued for any spin locks enrolled later. 723 */ 724 static int witness_spin_warn = 0; 725 726 /* Trim useless garbage from filenames. */ 727 static const char * 728 fixup_filename(const char *file) 729 { 730 731 if (file == NULL) 732 return (NULL); 733 while (strncmp(file, "../", 3) == 0) 734 file += 3; 735 return (file); 736 } 737 738 /* 739 * The WITNESS-enabled diagnostic code. Note that the witness code does 740 * assume that the early boot is single-threaded at least until after this 741 * routine is completed. 742 */ 743 static void 744 witness_initialize(void *dummy __unused) 745 { 746 struct lock_object *lock; 747 struct witness_order_list_entry *order; 748 struct witness *w, *w1; 749 int i; 750 751 w_data = malloc(sizeof (struct witness) * witness_count, M_WITNESS, 752 M_WAITOK | M_ZERO); 753 754 w_rmatrix = malloc(sizeof(*w_rmatrix) * (witness_count + 1), 755 M_WITNESS, M_WAITOK | M_ZERO); 756 757 for (i = 0; i < witness_count + 1; i++) { 758 w_rmatrix[i] = malloc(sizeof(*w_rmatrix[i]) * 759 (witness_count + 1), M_WITNESS, M_WAITOK | M_ZERO); 760 } 761 badstack_sbuf_size = witness_count * 256; 762 763 /* 764 * We have to release Giant before initializing its witness 765 * structure so that WITNESS doesn't get confused. 766 */ 767 mtx_unlock(&Giant); 768 mtx_assert(&Giant, MA_NOTOWNED); 769 770 CTR1(KTR_WITNESS, "%s: initializing witness", __func__); 771 mtx_init(&w_mtx, "witness lock", NULL, MTX_SPIN | MTX_QUIET | 772 MTX_NOWITNESS | MTX_NOPROFILE); 773 for (i = witness_count - 1; i >= 0; i--) { 774 w = &w_data[i]; 775 memset(w, 0, sizeof(*w)); 776 w_data[i].w_index = i; /* Witness index never changes. */ 777 witness_free(w); 778 } 779 KASSERT(STAILQ_FIRST(&w_free)->w_index == 0, 780 ("%s: Invalid list of free witness objects", __func__)); 781 782 /* Witness with index 0 is not used to aid in debugging. */ 783 STAILQ_REMOVE_HEAD(&w_free, w_list); 784 w_free_cnt--; 785 786 for (i = 0; i < witness_count; i++) { 787 memset(w_rmatrix[i], 0, sizeof(*w_rmatrix[i]) * 788 (witness_count + 1)); 789 } 790 791 for (i = 0; i < LOCK_CHILDCOUNT; i++) 792 witness_lock_list_free(&w_locklistdata[i]); 793 witness_init_hash_tables(); 794 795 /* First add in all the specified order lists. */ 796 for (order = order_lists; order->w_name != NULL; order++) { 797 w = enroll(order->w_name, order->w_class); 798 if (w == NULL) 799 continue; 800 w->w_file = "order list"; 801 for (order++; order->w_name != NULL; order++) { 802 w1 = enroll(order->w_name, order->w_class); 803 if (w1 == NULL) 804 continue; 805 w1->w_file = "order list"; 806 itismychild(w, w1); 807 w = w1; 808 } 809 } 810 witness_spin_warn = 1; 811 812 /* Iterate through all locks and add them to witness. */ 813 for (i = 0; pending_locks[i].wh_lock != NULL; i++) { 814 lock = pending_locks[i].wh_lock; 815 KASSERT(lock->lo_flags & LO_WITNESS, 816 ("%s: lock %s is on pending list but not LO_WITNESS", 817 __func__, lock->lo_name)); 818 lock->lo_witness = enroll(pending_locks[i].wh_type, 819 LOCK_CLASS(lock)); 820 } 821 822 /* Mark the witness code as being ready for use. */ 823 witness_cold = 0; 824 825 mtx_lock(&Giant); 826 } 827 SYSINIT(witness_init, SI_SUB_WITNESS, SI_ORDER_FIRST, witness_initialize, 828 NULL); 829 830 void 831 witness_init(struct lock_object *lock, const char *type) 832 { 833 struct lock_class *class; 834 835 /* Various sanity checks. */ 836 class = LOCK_CLASS(lock); 837 if ((lock->lo_flags & LO_RECURSABLE) != 0 && 838 (class->lc_flags & LC_RECURSABLE) == 0) 839 kassert_panic("%s: lock (%s) %s can not be recursable", 840 __func__, class->lc_name, lock->lo_name); 841 if ((lock->lo_flags & LO_SLEEPABLE) != 0 && 842 (class->lc_flags & LC_SLEEPABLE) == 0) 843 kassert_panic("%s: lock (%s) %s can not be sleepable", 844 __func__, class->lc_name, lock->lo_name); 845 if ((lock->lo_flags & LO_UPGRADABLE) != 0 && 846 (class->lc_flags & LC_UPGRADABLE) == 0) 847 kassert_panic("%s: lock (%s) %s can not be upgradable", 848 __func__, class->lc_name, lock->lo_name); 849 850 /* 851 * If we shouldn't watch this lock, then just clear lo_witness. 852 * Otherwise, if witness_cold is set, then it is too early to 853 * enroll this lock, so defer it to witness_initialize() by adding 854 * it to the pending_locks list. If it is not too early, then enroll 855 * the lock now. 856 */ 857 if (witness_watch < 1 || panicstr != NULL || 858 (lock->lo_flags & LO_WITNESS) == 0) 859 lock->lo_witness = NULL; 860 else if (witness_cold) { 861 pending_locks[pending_cnt].wh_lock = lock; 862 pending_locks[pending_cnt++].wh_type = type; 863 if (pending_cnt > WITNESS_PENDLIST) 864 panic("%s: pending locks list is too small, " 865 "increase WITNESS_PENDLIST\n", 866 __func__); 867 } else 868 lock->lo_witness = enroll(type, class); 869 } 870 871 void 872 witness_destroy(struct lock_object *lock) 873 { 874 struct lock_class *class; 875 struct witness *w; 876 877 class = LOCK_CLASS(lock); 878 879 if (witness_cold) 880 panic("lock (%s) %s destroyed while witness_cold", 881 class->lc_name, lock->lo_name); 882 883 /* XXX: need to verify that no one holds the lock */ 884 if ((lock->lo_flags & LO_WITNESS) == 0 || lock->lo_witness == NULL) 885 return; 886 w = lock->lo_witness; 887 888 mtx_lock_spin(&w_mtx); 889 MPASS(w->w_refcount > 0); 890 w->w_refcount--; 891 892 if (w->w_refcount == 0) 893 depart(w); 894 mtx_unlock_spin(&w_mtx); 895 } 896 897 #ifdef DDB 898 static void 899 witness_ddb_compute_levels(void) 900 { 901 struct witness *w; 902 903 /* 904 * First clear all levels. 905 */ 906 STAILQ_FOREACH(w, &w_all, w_list) 907 w->w_ddb_level = -1; 908 909 /* 910 * Look for locks with no parents and level all their descendants. 911 */ 912 STAILQ_FOREACH(w, &w_all, w_list) { 913 914 /* If the witness has ancestors (is not a root), skip it. */ 915 if (w->w_num_ancestors > 0) 916 continue; 917 witness_ddb_level_descendants(w, 0); 918 } 919 } 920 921 static void 922 witness_ddb_level_descendants(struct witness *w, int l) 923 { 924 int i; 925 926 if (w->w_ddb_level >= l) 927 return; 928 929 w->w_ddb_level = l; 930 l++; 931 932 for (i = 1; i <= w_max_used_index; i++) { 933 if (w_rmatrix[w->w_index][i] & WITNESS_PARENT) 934 witness_ddb_level_descendants(&w_data[i], l); 935 } 936 } 937 938 static void 939 witness_ddb_display_descendants(int(*prnt)(const char *fmt, ...), 940 struct witness *w, int indent) 941 { 942 int i; 943 944 for (i = 0; i < indent; i++) 945 prnt(" "); 946 prnt("%s (type: %s, depth: %d, active refs: %d)", 947 w->w_name, w->w_class->lc_name, 948 w->w_ddb_level, w->w_refcount); 949 if (w->w_displayed) { 950 prnt(" -- (already displayed)\n"); 951 return; 952 } 953 w->w_displayed = 1; 954 if (w->w_file != NULL && w->w_line != 0) 955 prnt(" -- last acquired @ %s:%d\n", fixup_filename(w->w_file), 956 w->w_line); 957 else 958 prnt(" -- never acquired\n"); 959 indent++; 960 WITNESS_INDEX_ASSERT(w->w_index); 961 for (i = 1; i <= w_max_used_index; i++) { 962 if (db_pager_quit) 963 return; 964 if (w_rmatrix[w->w_index][i] & WITNESS_PARENT) 965 witness_ddb_display_descendants(prnt, &w_data[i], 966 indent); 967 } 968 } 969 970 static void 971 witness_ddb_display_list(int(*prnt)(const char *fmt, ...), 972 struct witness_list *list) 973 { 974 struct witness *w; 975 976 STAILQ_FOREACH(w, list, w_typelist) { 977 if (w->w_file == NULL || w->w_ddb_level > 0) 978 continue; 979 980 /* This lock has no anscestors - display its descendants. */ 981 witness_ddb_display_descendants(prnt, w, 0); 982 if (db_pager_quit) 983 return; 984 } 985 } 986 987 static void 988 witness_ddb_display(int(*prnt)(const char *fmt, ...)) 989 { 990 struct witness *w; 991 992 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); 993 witness_ddb_compute_levels(); 994 995 /* Clear all the displayed flags. */ 996 STAILQ_FOREACH(w, &w_all, w_list) 997 w->w_displayed = 0; 998 999 /* 1000 * First, handle sleep locks which have been acquired at least 1001 * once. 1002 */ 1003 prnt("Sleep locks:\n"); 1004 witness_ddb_display_list(prnt, &w_sleep); 1005 if (db_pager_quit) 1006 return; 1007 1008 /* 1009 * Now do spin locks which have been acquired at least once. 1010 */ 1011 prnt("\nSpin locks:\n"); 1012 witness_ddb_display_list(prnt, &w_spin); 1013 if (db_pager_quit) 1014 return; 1015 1016 /* 1017 * Finally, any locks which have not been acquired yet. 1018 */ 1019 prnt("\nLocks which were never acquired:\n"); 1020 STAILQ_FOREACH(w, &w_all, w_list) { 1021 if (w->w_file != NULL || w->w_refcount == 0) 1022 continue; 1023 prnt("%s (type: %s, depth: %d)\n", w->w_name, 1024 w->w_class->lc_name, w->w_ddb_level); 1025 if (db_pager_quit) 1026 return; 1027 } 1028 } 1029 #endif /* DDB */ 1030 1031 int 1032 witness_defineorder(struct lock_object *lock1, struct lock_object *lock2) 1033 { 1034 1035 if (witness_watch == -1 || panicstr != NULL) 1036 return (0); 1037 1038 /* Require locks that witness knows about. */ 1039 if (lock1 == NULL || lock1->lo_witness == NULL || lock2 == NULL || 1040 lock2->lo_witness == NULL) 1041 return (EINVAL); 1042 1043 mtx_assert(&w_mtx, MA_NOTOWNED); 1044 mtx_lock_spin(&w_mtx); 1045 1046 /* 1047 * If we already have either an explicit or implied lock order that 1048 * is the other way around, then return an error. 1049 */ 1050 if (witness_watch && 1051 isitmydescendant(lock2->lo_witness, lock1->lo_witness)) { 1052 mtx_unlock_spin(&w_mtx); 1053 return (EDOOFUS); 1054 } 1055 1056 /* Try to add the new order. */ 1057 CTR3(KTR_WITNESS, "%s: adding %s as a child of %s", __func__, 1058 lock2->lo_witness->w_name, lock1->lo_witness->w_name); 1059 itismychild(lock1->lo_witness, lock2->lo_witness); 1060 mtx_unlock_spin(&w_mtx); 1061 return (0); 1062 } 1063 1064 void 1065 witness_checkorder(struct lock_object *lock, int flags, const char *file, 1066 int line, struct lock_object *interlock) 1067 { 1068 struct lock_list_entry *lock_list, *lle; 1069 struct lock_instance *lock1, *lock2, *plock; 1070 struct lock_class *class, *iclass; 1071 struct witness *w, *w1; 1072 struct thread *td; 1073 int i, j; 1074 1075 if (witness_cold || witness_watch < 1 || lock->lo_witness == NULL || 1076 panicstr != NULL) 1077 return; 1078 1079 w = lock->lo_witness; 1080 class = LOCK_CLASS(lock); 1081 td = curthread; 1082 1083 if (class->lc_flags & LC_SLEEPLOCK) { 1084 1085 /* 1086 * Since spin locks include a critical section, this check 1087 * implicitly enforces a lock order of all sleep locks before 1088 * all spin locks. 1089 */ 1090 if (td->td_critnest != 0 && !kdb_active) 1091 kassert_panic("acquiring blockable sleep lock with " 1092 "spinlock or critical section held (%s) %s @ %s:%d", 1093 class->lc_name, lock->lo_name, 1094 fixup_filename(file), line); 1095 1096 /* 1097 * If this is the first lock acquired then just return as 1098 * no order checking is needed. 1099 */ 1100 lock_list = td->td_sleeplocks; 1101 if (lock_list == NULL || lock_list->ll_count == 0) 1102 return; 1103 } else { 1104 1105 /* 1106 * If this is the first lock, just return as no order 1107 * checking is needed. Avoid problems with thread 1108 * migration pinning the thread while checking if 1109 * spinlocks are held. If at least one spinlock is held 1110 * the thread is in a safe path and it is allowed to 1111 * unpin it. 1112 */ 1113 sched_pin(); 1114 lock_list = PCPU_GET(spinlocks); 1115 if (lock_list == NULL || lock_list->ll_count == 0) { 1116 sched_unpin(); 1117 return; 1118 } 1119 sched_unpin(); 1120 } 1121 1122 /* 1123 * Check to see if we are recursing on a lock we already own. If 1124 * so, make sure that we don't mismatch exclusive and shared lock 1125 * acquires. 1126 */ 1127 lock1 = find_instance(lock_list, lock); 1128 if (lock1 != NULL) { 1129 if ((lock1->li_flags & LI_EXCLUSIVE) != 0 && 1130 (flags & LOP_EXCLUSIVE) == 0) { 1131 witness_output("shared lock of (%s) %s @ %s:%d\n", 1132 class->lc_name, lock->lo_name, 1133 fixup_filename(file), line); 1134 witness_output("while exclusively locked from %s:%d\n", 1135 fixup_filename(lock1->li_file), lock1->li_line); 1136 kassert_panic("excl->share"); 1137 } 1138 if ((lock1->li_flags & LI_EXCLUSIVE) == 0 && 1139 (flags & LOP_EXCLUSIVE) != 0) { 1140 witness_output("exclusive lock of (%s) %s @ %s:%d\n", 1141 class->lc_name, lock->lo_name, 1142 fixup_filename(file), line); 1143 witness_output("while share locked from %s:%d\n", 1144 fixup_filename(lock1->li_file), lock1->li_line); 1145 kassert_panic("share->excl"); 1146 } 1147 return; 1148 } 1149 1150 /* Warn if the interlock is not locked exactly once. */ 1151 if (interlock != NULL) { 1152 iclass = LOCK_CLASS(interlock); 1153 lock1 = find_instance(lock_list, interlock); 1154 if (lock1 == NULL) 1155 kassert_panic("interlock (%s) %s not locked @ %s:%d", 1156 iclass->lc_name, interlock->lo_name, 1157 fixup_filename(file), line); 1158 else if ((lock1->li_flags & LI_RECURSEMASK) != 0) 1159 kassert_panic("interlock (%s) %s recursed @ %s:%d", 1160 iclass->lc_name, interlock->lo_name, 1161 fixup_filename(file), line); 1162 } 1163 1164 /* 1165 * Find the previously acquired lock, but ignore interlocks. 1166 */ 1167 plock = &lock_list->ll_children[lock_list->ll_count - 1]; 1168 if (interlock != NULL && plock->li_lock == interlock) { 1169 if (lock_list->ll_count > 1) 1170 plock = 1171 &lock_list->ll_children[lock_list->ll_count - 2]; 1172 else { 1173 lle = lock_list->ll_next; 1174 1175 /* 1176 * The interlock is the only lock we hold, so 1177 * simply return. 1178 */ 1179 if (lle == NULL) 1180 return; 1181 plock = &lle->ll_children[lle->ll_count - 1]; 1182 } 1183 } 1184 1185 /* 1186 * Try to perform most checks without a lock. If this succeeds we 1187 * can skip acquiring the lock and return success. Otherwise we redo 1188 * the check with the lock held to handle races with concurrent updates. 1189 */ 1190 w1 = plock->li_lock->lo_witness; 1191 if (witness_lock_order_check(w1, w)) 1192 return; 1193 1194 mtx_lock_spin(&w_mtx); 1195 if (witness_lock_order_check(w1, w)) { 1196 mtx_unlock_spin(&w_mtx); 1197 return; 1198 } 1199 witness_lock_order_add(w1, w); 1200 1201 /* 1202 * Check for duplicate locks of the same type. Note that we only 1203 * have to check for this on the last lock we just acquired. Any 1204 * other cases will be caught as lock order violations. 1205 */ 1206 if (w1 == w) { 1207 i = w->w_index; 1208 if (!(lock->lo_flags & LO_DUPOK) && !(flags & LOP_DUPOK) && 1209 !(w_rmatrix[i][i] & WITNESS_REVERSAL)) { 1210 w_rmatrix[i][i] |= WITNESS_REVERSAL; 1211 w->w_reversed = 1; 1212 mtx_unlock_spin(&w_mtx); 1213 witness_output( 1214 "acquiring duplicate lock of same type: \"%s\"\n", 1215 w->w_name); 1216 witness_output(" 1st %s @ %s:%d\n", plock->li_lock->lo_name, 1217 fixup_filename(plock->li_file), plock->li_line); 1218 witness_output(" 2nd %s @ %s:%d\n", lock->lo_name, 1219 fixup_filename(file), line); 1220 witness_debugger(1, __func__); 1221 } else 1222 mtx_unlock_spin(&w_mtx); 1223 return; 1224 } 1225 mtx_assert(&w_mtx, MA_OWNED); 1226 1227 /* 1228 * If we know that the lock we are acquiring comes after 1229 * the lock we most recently acquired in the lock order tree, 1230 * then there is no need for any further checks. 1231 */ 1232 if (isitmychild(w1, w)) 1233 goto out; 1234 1235 for (j = 0, lle = lock_list; lle != NULL; lle = lle->ll_next) { 1236 for (i = lle->ll_count - 1; i >= 0; i--, j++) { 1237 1238 MPASS(j < LOCK_CHILDCOUNT * LOCK_NCHILDREN); 1239 lock1 = &lle->ll_children[i]; 1240 1241 /* 1242 * Ignore the interlock. 1243 */ 1244 if (interlock == lock1->li_lock) 1245 continue; 1246 1247 /* 1248 * If this lock doesn't undergo witness checking, 1249 * then skip it. 1250 */ 1251 w1 = lock1->li_lock->lo_witness; 1252 if (w1 == NULL) { 1253 KASSERT((lock1->li_lock->lo_flags & LO_WITNESS) == 0, 1254 ("lock missing witness structure")); 1255 continue; 1256 } 1257 1258 /* 1259 * If we are locking Giant and this is a sleepable 1260 * lock, then skip it. 1261 */ 1262 if ((lock1->li_lock->lo_flags & LO_SLEEPABLE) != 0 && 1263 lock == &Giant.lock_object) 1264 continue; 1265 1266 /* 1267 * If we are locking a sleepable lock and this lock 1268 * is Giant, then skip it. 1269 */ 1270 if ((lock->lo_flags & LO_SLEEPABLE) != 0 && 1271 lock1->li_lock == &Giant.lock_object) 1272 continue; 1273 1274 /* 1275 * If we are locking a sleepable lock and this lock 1276 * isn't sleepable, we want to treat it as a lock 1277 * order violation to enfore a general lock order of 1278 * sleepable locks before non-sleepable locks. 1279 */ 1280 if (((lock->lo_flags & LO_SLEEPABLE) != 0 && 1281 (lock1->li_lock->lo_flags & LO_SLEEPABLE) == 0)) 1282 goto reversal; 1283 1284 /* 1285 * If we are locking Giant and this is a non-sleepable 1286 * lock, then treat it as a reversal. 1287 */ 1288 if ((lock1->li_lock->lo_flags & LO_SLEEPABLE) == 0 && 1289 lock == &Giant.lock_object) 1290 goto reversal; 1291 1292 /* 1293 * Check the lock order hierarchy for a reveresal. 1294 */ 1295 if (!isitmydescendant(w, w1)) 1296 continue; 1297 reversal: 1298 1299 /* 1300 * We have a lock order violation, check to see if it 1301 * is allowed or has already been yelled about. 1302 */ 1303 #ifdef BLESSING 1304 1305 /* 1306 * If the lock order is blessed, just bail. We don't 1307 * look for other lock order violations though, which 1308 * may be a bug. 1309 */ 1310 if (blessed(w, w1)) 1311 goto out; 1312 #endif 1313 1314 /* Bail if this violation is known */ 1315 if (w_rmatrix[w1->w_index][w->w_index] & WITNESS_REVERSAL) 1316 goto out; 1317 1318 /* Record this as a violation */ 1319 w_rmatrix[w1->w_index][w->w_index] |= WITNESS_REVERSAL; 1320 w_rmatrix[w->w_index][w1->w_index] |= WITNESS_REVERSAL; 1321 w->w_reversed = w1->w_reversed = 1; 1322 witness_increment_graph_generation(); 1323 mtx_unlock_spin(&w_mtx); 1324 1325 #ifdef WITNESS_NO_VNODE 1326 /* 1327 * There are known LORs between VNODE locks. They are 1328 * not an indication of a bug. VNODE locks are flagged 1329 * as such (LO_IS_VNODE) and we don't yell if the LOR 1330 * is between 2 VNODE locks. 1331 */ 1332 if ((lock->lo_flags & LO_IS_VNODE) != 0 && 1333 (lock1->li_lock->lo_flags & LO_IS_VNODE) != 0) 1334 return; 1335 #endif 1336 1337 /* 1338 * Ok, yell about it. 1339 */ 1340 if (((lock->lo_flags & LO_SLEEPABLE) != 0 && 1341 (lock1->li_lock->lo_flags & LO_SLEEPABLE) == 0)) 1342 witness_output( 1343 "lock order reversal: (sleepable after non-sleepable)\n"); 1344 else if ((lock1->li_lock->lo_flags & LO_SLEEPABLE) == 0 1345 && lock == &Giant.lock_object) 1346 witness_output( 1347 "lock order reversal: (Giant after non-sleepable)\n"); 1348 else 1349 witness_output("lock order reversal:\n"); 1350 1351 /* 1352 * Try to locate an earlier lock with 1353 * witness w in our list. 1354 */ 1355 do { 1356 lock2 = &lle->ll_children[i]; 1357 MPASS(lock2->li_lock != NULL); 1358 if (lock2->li_lock->lo_witness == w) 1359 break; 1360 if (i == 0 && lle->ll_next != NULL) { 1361 lle = lle->ll_next; 1362 i = lle->ll_count - 1; 1363 MPASS(i >= 0 && i < LOCK_NCHILDREN); 1364 } else 1365 i--; 1366 } while (i >= 0); 1367 if (i < 0) { 1368 witness_output(" 1st %p %s (%s) @ %s:%d\n", 1369 lock1->li_lock, lock1->li_lock->lo_name, 1370 w1->w_name, fixup_filename(lock1->li_file), 1371 lock1->li_line); 1372 witness_output(" 2nd %p %s (%s) @ %s:%d\n", lock, 1373 lock->lo_name, w->w_name, 1374 fixup_filename(file), line); 1375 } else { 1376 witness_output(" 1st %p %s (%s) @ %s:%d\n", 1377 lock2->li_lock, lock2->li_lock->lo_name, 1378 lock2->li_lock->lo_witness->w_name, 1379 fixup_filename(lock2->li_file), 1380 lock2->li_line); 1381 witness_output(" 2nd %p %s (%s) @ %s:%d\n", 1382 lock1->li_lock, lock1->li_lock->lo_name, 1383 w1->w_name, fixup_filename(lock1->li_file), 1384 lock1->li_line); 1385 witness_output(" 3rd %p %s (%s) @ %s:%d\n", lock, 1386 lock->lo_name, w->w_name, 1387 fixup_filename(file), line); 1388 } 1389 witness_debugger(1, __func__); 1390 return; 1391 } 1392 } 1393 1394 /* 1395 * If requested, build a new lock order. However, don't build a new 1396 * relationship between a sleepable lock and Giant if it is in the 1397 * wrong direction. The correct lock order is that sleepable locks 1398 * always come before Giant. 1399 */ 1400 if (flags & LOP_NEWORDER && 1401 !(plock->li_lock == &Giant.lock_object && 1402 (lock->lo_flags & LO_SLEEPABLE) != 0)) { 1403 CTR3(KTR_WITNESS, "%s: adding %s as a child of %s", __func__, 1404 w->w_name, plock->li_lock->lo_witness->w_name); 1405 itismychild(plock->li_lock->lo_witness, w); 1406 } 1407 out: 1408 mtx_unlock_spin(&w_mtx); 1409 } 1410 1411 void 1412 witness_lock(struct lock_object *lock, int flags, const char *file, int line) 1413 { 1414 struct lock_list_entry **lock_list, *lle; 1415 struct lock_instance *instance; 1416 struct witness *w; 1417 struct thread *td; 1418 1419 if (witness_cold || witness_watch == -1 || lock->lo_witness == NULL || 1420 panicstr != NULL) 1421 return; 1422 w = lock->lo_witness; 1423 td = curthread; 1424 1425 /* Determine lock list for this lock. */ 1426 if (LOCK_CLASS(lock)->lc_flags & LC_SLEEPLOCK) 1427 lock_list = &td->td_sleeplocks; 1428 else 1429 lock_list = PCPU_PTR(spinlocks); 1430 1431 /* Check to see if we are recursing on a lock we already own. */ 1432 instance = find_instance(*lock_list, lock); 1433 if (instance != NULL) { 1434 instance->li_flags++; 1435 CTR4(KTR_WITNESS, "%s: pid %d recursed on %s r=%d", __func__, 1436 td->td_proc->p_pid, lock->lo_name, 1437 instance->li_flags & LI_RECURSEMASK); 1438 instance->li_file = file; 1439 instance->li_line = line; 1440 return; 1441 } 1442 1443 /* Update per-witness last file and line acquire. */ 1444 w->w_file = file; 1445 w->w_line = line; 1446 1447 /* Find the next open lock instance in the list and fill it. */ 1448 lle = *lock_list; 1449 if (lle == NULL || lle->ll_count == LOCK_NCHILDREN) { 1450 lle = witness_lock_list_get(); 1451 if (lle == NULL) 1452 return; 1453 lle->ll_next = *lock_list; 1454 CTR3(KTR_WITNESS, "%s: pid %d added lle %p", __func__, 1455 td->td_proc->p_pid, lle); 1456 *lock_list = lle; 1457 } 1458 instance = &lle->ll_children[lle->ll_count++]; 1459 instance->li_lock = lock; 1460 instance->li_line = line; 1461 instance->li_file = file; 1462 if ((flags & LOP_EXCLUSIVE) != 0) 1463 instance->li_flags = LI_EXCLUSIVE; 1464 else 1465 instance->li_flags = 0; 1466 CTR4(KTR_WITNESS, "%s: pid %d added %s as lle[%d]", __func__, 1467 td->td_proc->p_pid, lock->lo_name, lle->ll_count - 1); 1468 } 1469 1470 void 1471 witness_upgrade(struct lock_object *lock, int flags, const char *file, int line) 1472 { 1473 struct lock_instance *instance; 1474 struct lock_class *class; 1475 1476 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); 1477 if (lock->lo_witness == NULL || witness_watch == -1 || panicstr != NULL) 1478 return; 1479 class = LOCK_CLASS(lock); 1480 if (witness_watch) { 1481 if ((lock->lo_flags & LO_UPGRADABLE) == 0) 1482 kassert_panic( 1483 "upgrade of non-upgradable lock (%s) %s @ %s:%d", 1484 class->lc_name, lock->lo_name, 1485 fixup_filename(file), line); 1486 if ((class->lc_flags & LC_SLEEPLOCK) == 0) 1487 kassert_panic( 1488 "upgrade of non-sleep lock (%s) %s @ %s:%d", 1489 class->lc_name, lock->lo_name, 1490 fixup_filename(file), line); 1491 } 1492 instance = find_instance(curthread->td_sleeplocks, lock); 1493 if (instance == NULL) { 1494 kassert_panic("upgrade of unlocked lock (%s) %s @ %s:%d", 1495 class->lc_name, lock->lo_name, 1496 fixup_filename(file), line); 1497 return; 1498 } 1499 if (witness_watch) { 1500 if ((instance->li_flags & LI_EXCLUSIVE) != 0) 1501 kassert_panic( 1502 "upgrade of exclusive lock (%s) %s @ %s:%d", 1503 class->lc_name, lock->lo_name, 1504 fixup_filename(file), line); 1505 if ((instance->li_flags & LI_RECURSEMASK) != 0) 1506 kassert_panic( 1507 "upgrade of recursed lock (%s) %s r=%d @ %s:%d", 1508 class->lc_name, lock->lo_name, 1509 instance->li_flags & LI_RECURSEMASK, 1510 fixup_filename(file), line); 1511 } 1512 instance->li_flags |= LI_EXCLUSIVE; 1513 } 1514 1515 void 1516 witness_downgrade(struct lock_object *lock, int flags, const char *file, 1517 int line) 1518 { 1519 struct lock_instance *instance; 1520 struct lock_class *class; 1521 1522 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); 1523 if (lock->lo_witness == NULL || witness_watch == -1 || panicstr != NULL) 1524 return; 1525 class = LOCK_CLASS(lock); 1526 if (witness_watch) { 1527 if ((lock->lo_flags & LO_UPGRADABLE) == 0) 1528 kassert_panic( 1529 "downgrade of non-upgradable lock (%s) %s @ %s:%d", 1530 class->lc_name, lock->lo_name, 1531 fixup_filename(file), line); 1532 if ((class->lc_flags & LC_SLEEPLOCK) == 0) 1533 kassert_panic( 1534 "downgrade of non-sleep lock (%s) %s @ %s:%d", 1535 class->lc_name, lock->lo_name, 1536 fixup_filename(file), line); 1537 } 1538 instance = find_instance(curthread->td_sleeplocks, lock); 1539 if (instance == NULL) { 1540 kassert_panic("downgrade of unlocked lock (%s) %s @ %s:%d", 1541 class->lc_name, lock->lo_name, 1542 fixup_filename(file), line); 1543 return; 1544 } 1545 if (witness_watch) { 1546 if ((instance->li_flags & LI_EXCLUSIVE) == 0) 1547 kassert_panic( 1548 "downgrade of shared lock (%s) %s @ %s:%d", 1549 class->lc_name, lock->lo_name, 1550 fixup_filename(file), line); 1551 if ((instance->li_flags & LI_RECURSEMASK) != 0) 1552 kassert_panic( 1553 "downgrade of recursed lock (%s) %s r=%d @ %s:%d", 1554 class->lc_name, lock->lo_name, 1555 instance->li_flags & LI_RECURSEMASK, 1556 fixup_filename(file), line); 1557 } 1558 instance->li_flags &= ~LI_EXCLUSIVE; 1559 } 1560 1561 void 1562 witness_unlock(struct lock_object *lock, int flags, const char *file, int line) 1563 { 1564 struct lock_list_entry **lock_list, *lle; 1565 struct lock_instance *instance; 1566 struct lock_class *class; 1567 struct thread *td; 1568 register_t s; 1569 int i, j; 1570 1571 if (witness_cold || lock->lo_witness == NULL || panicstr != NULL) 1572 return; 1573 td = curthread; 1574 class = LOCK_CLASS(lock); 1575 1576 /* Find lock instance associated with this lock. */ 1577 if (class->lc_flags & LC_SLEEPLOCK) 1578 lock_list = &td->td_sleeplocks; 1579 else 1580 lock_list = PCPU_PTR(spinlocks); 1581 lle = *lock_list; 1582 for (; *lock_list != NULL; lock_list = &(*lock_list)->ll_next) 1583 for (i = 0; i < (*lock_list)->ll_count; i++) { 1584 instance = &(*lock_list)->ll_children[i]; 1585 if (instance->li_lock == lock) 1586 goto found; 1587 } 1588 1589 /* 1590 * When disabling WITNESS through witness_watch we could end up in 1591 * having registered locks in the td_sleeplocks queue. 1592 * We have to make sure we flush these queues, so just search for 1593 * eventual register locks and remove them. 1594 */ 1595 if (witness_watch > 0) { 1596 kassert_panic("lock (%s) %s not locked @ %s:%d", class->lc_name, 1597 lock->lo_name, fixup_filename(file), line); 1598 return; 1599 } else { 1600 return; 1601 } 1602 found: 1603 1604 /* First, check for shared/exclusive mismatches. */ 1605 if ((instance->li_flags & LI_EXCLUSIVE) != 0 && witness_watch > 0 && 1606 (flags & LOP_EXCLUSIVE) == 0) { 1607 witness_output("shared unlock of (%s) %s @ %s:%d\n", 1608 class->lc_name, lock->lo_name, fixup_filename(file), line); 1609 witness_output("while exclusively locked from %s:%d\n", 1610 fixup_filename(instance->li_file), instance->li_line); 1611 kassert_panic("excl->ushare"); 1612 } 1613 if ((instance->li_flags & LI_EXCLUSIVE) == 0 && witness_watch > 0 && 1614 (flags & LOP_EXCLUSIVE) != 0) { 1615 witness_output("exclusive unlock of (%s) %s @ %s:%d\n", 1616 class->lc_name, lock->lo_name, fixup_filename(file), line); 1617 witness_output("while share locked from %s:%d\n", 1618 fixup_filename(instance->li_file), 1619 instance->li_line); 1620 kassert_panic("share->uexcl"); 1621 } 1622 /* If we are recursed, unrecurse. */ 1623 if ((instance->li_flags & LI_RECURSEMASK) > 0) { 1624 CTR4(KTR_WITNESS, "%s: pid %d unrecursed on %s r=%d", __func__, 1625 td->td_proc->p_pid, instance->li_lock->lo_name, 1626 instance->li_flags); 1627 instance->li_flags--; 1628 return; 1629 } 1630 /* The lock is now being dropped, check for NORELEASE flag */ 1631 if ((instance->li_flags & LI_NORELEASE) != 0 && witness_watch > 0) { 1632 witness_output("forbidden unlock of (%s) %s @ %s:%d\n", 1633 class->lc_name, lock->lo_name, fixup_filename(file), line); 1634 kassert_panic("lock marked norelease"); 1635 } 1636 1637 /* Otherwise, remove this item from the list. */ 1638 s = intr_disable(); 1639 CTR4(KTR_WITNESS, "%s: pid %d removed %s from lle[%d]", __func__, 1640 td->td_proc->p_pid, instance->li_lock->lo_name, 1641 (*lock_list)->ll_count - 1); 1642 for (j = i; j < (*lock_list)->ll_count - 1; j++) 1643 (*lock_list)->ll_children[j] = 1644 (*lock_list)->ll_children[j + 1]; 1645 (*lock_list)->ll_count--; 1646 intr_restore(s); 1647 1648 /* 1649 * In order to reduce contention on w_mtx, we want to keep always an 1650 * head object into lists so that frequent allocation from the 1651 * free witness pool (and subsequent locking) is avoided. 1652 * In order to maintain the current code simple, when the head 1653 * object is totally unloaded it means also that we do not have 1654 * further objects in the list, so the list ownership needs to be 1655 * hand over to another object if the current head needs to be freed. 1656 */ 1657 if ((*lock_list)->ll_count == 0) { 1658 if (*lock_list == lle) { 1659 if (lle->ll_next == NULL) 1660 return; 1661 } else 1662 lle = *lock_list; 1663 *lock_list = lle->ll_next; 1664 CTR3(KTR_WITNESS, "%s: pid %d removed lle %p", __func__, 1665 td->td_proc->p_pid, lle); 1666 witness_lock_list_free(lle); 1667 } 1668 } 1669 1670 void 1671 witness_thread_exit(struct thread *td) 1672 { 1673 struct lock_list_entry *lle; 1674 int i, n; 1675 1676 lle = td->td_sleeplocks; 1677 if (lle == NULL || panicstr != NULL) 1678 return; 1679 if (lle->ll_count != 0) { 1680 for (n = 0; lle != NULL; lle = lle->ll_next) 1681 for (i = lle->ll_count - 1; i >= 0; i--) { 1682 if (n == 0) 1683 witness_output( 1684 "Thread %p exiting with the following locks held:\n", td); 1685 n++; 1686 witness_list_lock(&lle->ll_children[i], 1687 witness_output); 1688 1689 } 1690 kassert_panic( 1691 "Thread %p cannot exit while holding sleeplocks\n", td); 1692 } 1693 witness_lock_list_free(lle); 1694 } 1695 1696 /* 1697 * Warn if any locks other than 'lock' are held. Flags can be passed in to 1698 * exempt Giant and sleepable locks from the checks as well. If any 1699 * non-exempt locks are held, then a supplied message is printed to the 1700 * output channel along with a list of the offending locks. If indicated in the 1701 * flags then a failure results in a panic as well. 1702 */ 1703 int 1704 witness_warn(int flags, struct lock_object *lock, const char *fmt, ...) 1705 { 1706 struct lock_list_entry *lock_list, *lle; 1707 struct lock_instance *lock1; 1708 struct thread *td; 1709 va_list ap; 1710 int i, n; 1711 1712 if (witness_cold || witness_watch < 1 || panicstr != NULL) 1713 return (0); 1714 n = 0; 1715 td = curthread; 1716 for (lle = td->td_sleeplocks; lle != NULL; lle = lle->ll_next) 1717 for (i = lle->ll_count - 1; i >= 0; i--) { 1718 lock1 = &lle->ll_children[i]; 1719 if (lock1->li_lock == lock) 1720 continue; 1721 if (flags & WARN_GIANTOK && 1722 lock1->li_lock == &Giant.lock_object) 1723 continue; 1724 if (flags & WARN_SLEEPOK && 1725 (lock1->li_lock->lo_flags & LO_SLEEPABLE) != 0) 1726 continue; 1727 if (n == 0) { 1728 va_start(ap, fmt); 1729 witness_voutput(fmt, ap); 1730 va_end(ap); 1731 witness_output( 1732 " with the following %slocks held:\n", 1733 (flags & WARN_SLEEPOK) != 0 ? 1734 "non-sleepable " : ""); 1735 } 1736 n++; 1737 witness_list_lock(lock1, witness_output); 1738 } 1739 1740 /* 1741 * Pin the thread in order to avoid problems with thread migration. 1742 * Once that all verifies are passed about spinlocks ownership, 1743 * the thread is in a safe path and it can be unpinned. 1744 */ 1745 sched_pin(); 1746 lock_list = PCPU_GET(spinlocks); 1747 if (lock_list != NULL && lock_list->ll_count != 0) { 1748 sched_unpin(); 1749 1750 /* 1751 * We should only have one spinlock and as long as 1752 * the flags cannot match for this locks class, 1753 * check if the first spinlock is the one curthread 1754 * should hold. 1755 */ 1756 lock1 = &lock_list->ll_children[lock_list->ll_count - 1]; 1757 if (lock_list->ll_count == 1 && lock_list->ll_next == NULL && 1758 lock1->li_lock == lock && n == 0) 1759 return (0); 1760 1761 va_start(ap, fmt); 1762 witness_voutput(fmt, ap); 1763 va_end(ap); 1764 witness_output(" with the following %slocks held:\n", 1765 (flags & WARN_SLEEPOK) != 0 ? "non-sleepable " : ""); 1766 n += witness_list_locks(&lock_list, witness_output); 1767 } else 1768 sched_unpin(); 1769 if (flags & WARN_PANIC && n) 1770 kassert_panic("%s", __func__); 1771 else 1772 witness_debugger(n, __func__); 1773 return (n); 1774 } 1775 1776 const char * 1777 witness_file(struct lock_object *lock) 1778 { 1779 struct witness *w; 1780 1781 if (witness_cold || witness_watch < 1 || lock->lo_witness == NULL) 1782 return ("?"); 1783 w = lock->lo_witness; 1784 return (w->w_file); 1785 } 1786 1787 int 1788 witness_line(struct lock_object *lock) 1789 { 1790 struct witness *w; 1791 1792 if (witness_cold || witness_watch < 1 || lock->lo_witness == NULL) 1793 return (0); 1794 w = lock->lo_witness; 1795 return (w->w_line); 1796 } 1797 1798 static struct witness * 1799 enroll(const char *description, struct lock_class *lock_class) 1800 { 1801 struct witness *w; 1802 struct witness_list *typelist; 1803 1804 MPASS(description != NULL); 1805 1806 if (witness_watch == -1 || panicstr != NULL) 1807 return (NULL); 1808 if ((lock_class->lc_flags & LC_SPINLOCK)) { 1809 if (witness_skipspin) 1810 return (NULL); 1811 else 1812 typelist = &w_spin; 1813 } else if ((lock_class->lc_flags & LC_SLEEPLOCK)) { 1814 typelist = &w_sleep; 1815 } else { 1816 kassert_panic("lock class %s is not sleep or spin", 1817 lock_class->lc_name); 1818 return (NULL); 1819 } 1820 1821 mtx_lock_spin(&w_mtx); 1822 w = witness_hash_get(description); 1823 if (w) 1824 goto found; 1825 if ((w = witness_get()) == NULL) 1826 return (NULL); 1827 MPASS(strlen(description) < MAX_W_NAME); 1828 strcpy(w->w_name, description); 1829 w->w_class = lock_class; 1830 w->w_refcount = 1; 1831 STAILQ_INSERT_HEAD(&w_all, w, w_list); 1832 if (lock_class->lc_flags & LC_SPINLOCK) { 1833 STAILQ_INSERT_HEAD(&w_spin, w, w_typelist); 1834 w_spin_cnt++; 1835 } else if (lock_class->lc_flags & LC_SLEEPLOCK) { 1836 STAILQ_INSERT_HEAD(&w_sleep, w, w_typelist); 1837 w_sleep_cnt++; 1838 } 1839 1840 /* Insert new witness into the hash */ 1841 witness_hash_put(w); 1842 witness_increment_graph_generation(); 1843 mtx_unlock_spin(&w_mtx); 1844 return (w); 1845 found: 1846 w->w_refcount++; 1847 mtx_unlock_spin(&w_mtx); 1848 if (lock_class != w->w_class) 1849 kassert_panic( 1850 "lock (%s) %s does not match earlier (%s) lock", 1851 description, lock_class->lc_name, 1852 w->w_class->lc_name); 1853 return (w); 1854 } 1855 1856 static void 1857 depart(struct witness *w) 1858 { 1859 struct witness_list *list; 1860 1861 MPASS(w->w_refcount == 0); 1862 if (w->w_class->lc_flags & LC_SLEEPLOCK) { 1863 list = &w_sleep; 1864 w_sleep_cnt--; 1865 } else { 1866 list = &w_spin; 1867 w_spin_cnt--; 1868 } 1869 /* 1870 * Set file to NULL as it may point into a loadable module. 1871 */ 1872 w->w_file = NULL; 1873 w->w_line = 0; 1874 witness_increment_graph_generation(); 1875 } 1876 1877 1878 static void 1879 adopt(struct witness *parent, struct witness *child) 1880 { 1881 int pi, ci, i, j; 1882 1883 if (witness_cold == 0) 1884 mtx_assert(&w_mtx, MA_OWNED); 1885 1886 /* If the relationship is already known, there's no work to be done. */ 1887 if (isitmychild(parent, child)) 1888 return; 1889 1890 /* When the structure of the graph changes, bump up the generation. */ 1891 witness_increment_graph_generation(); 1892 1893 /* 1894 * The hard part ... create the direct relationship, then propagate all 1895 * indirect relationships. 1896 */ 1897 pi = parent->w_index; 1898 ci = child->w_index; 1899 WITNESS_INDEX_ASSERT(pi); 1900 WITNESS_INDEX_ASSERT(ci); 1901 MPASS(pi != ci); 1902 w_rmatrix[pi][ci] |= WITNESS_PARENT; 1903 w_rmatrix[ci][pi] |= WITNESS_CHILD; 1904 1905 /* 1906 * If parent was not already an ancestor of child, 1907 * then we increment the descendant and ancestor counters. 1908 */ 1909 if ((w_rmatrix[pi][ci] & WITNESS_ANCESTOR) == 0) { 1910 parent->w_num_descendants++; 1911 child->w_num_ancestors++; 1912 } 1913 1914 /* 1915 * Find each ancestor of 'pi'. Note that 'pi' itself is counted as 1916 * an ancestor of 'pi' during this loop. 1917 */ 1918 for (i = 1; i <= w_max_used_index; i++) { 1919 if ((w_rmatrix[i][pi] & WITNESS_ANCESTOR_MASK) == 0 && 1920 (i != pi)) 1921 continue; 1922 1923 /* Find each descendant of 'i' and mark it as a descendant. */ 1924 for (j = 1; j <= w_max_used_index; j++) { 1925 1926 /* 1927 * Skip children that are already marked as 1928 * descendants of 'i'. 1929 */ 1930 if (w_rmatrix[i][j] & WITNESS_ANCESTOR_MASK) 1931 continue; 1932 1933 /* 1934 * We are only interested in descendants of 'ci'. Note 1935 * that 'ci' itself is counted as a descendant of 'ci'. 1936 */ 1937 if ((w_rmatrix[ci][j] & WITNESS_ANCESTOR_MASK) == 0 && 1938 (j != ci)) 1939 continue; 1940 w_rmatrix[i][j] |= WITNESS_ANCESTOR; 1941 w_rmatrix[j][i] |= WITNESS_DESCENDANT; 1942 w_data[i].w_num_descendants++; 1943 w_data[j].w_num_ancestors++; 1944 1945 /* 1946 * Make sure we aren't marking a node as both an 1947 * ancestor and descendant. We should have caught 1948 * this as a lock order reversal earlier. 1949 */ 1950 if ((w_rmatrix[i][j] & WITNESS_ANCESTOR_MASK) && 1951 (w_rmatrix[i][j] & WITNESS_DESCENDANT_MASK)) { 1952 printf("witness rmatrix paradox! [%d][%d]=%d " 1953 "both ancestor and descendant\n", 1954 i, j, w_rmatrix[i][j]); 1955 kdb_backtrace(); 1956 printf("Witness disabled.\n"); 1957 witness_watch = -1; 1958 } 1959 if ((w_rmatrix[j][i] & WITNESS_ANCESTOR_MASK) && 1960 (w_rmatrix[j][i] & WITNESS_DESCENDANT_MASK)) { 1961 printf("witness rmatrix paradox! [%d][%d]=%d " 1962 "both ancestor and descendant\n", 1963 j, i, w_rmatrix[j][i]); 1964 kdb_backtrace(); 1965 printf("Witness disabled.\n"); 1966 witness_watch = -1; 1967 } 1968 } 1969 } 1970 } 1971 1972 static void 1973 itismychild(struct witness *parent, struct witness *child) 1974 { 1975 int unlocked; 1976 1977 MPASS(child != NULL && parent != NULL); 1978 if (witness_cold == 0) 1979 mtx_assert(&w_mtx, MA_OWNED); 1980 1981 if (!witness_lock_type_equal(parent, child)) { 1982 if (witness_cold == 0) { 1983 unlocked = 1; 1984 mtx_unlock_spin(&w_mtx); 1985 } else { 1986 unlocked = 0; 1987 } 1988 kassert_panic( 1989 "%s: parent \"%s\" (%s) and child \"%s\" (%s) are not " 1990 "the same lock type", __func__, parent->w_name, 1991 parent->w_class->lc_name, child->w_name, 1992 child->w_class->lc_name); 1993 if (unlocked) 1994 mtx_lock_spin(&w_mtx); 1995 } 1996 adopt(parent, child); 1997 } 1998 1999 /* 2000 * Generic code for the isitmy*() functions. The rmask parameter is the 2001 * expected relationship of w1 to w2. 2002 */ 2003 static int 2004 _isitmyx(struct witness *w1, struct witness *w2, int rmask, const char *fname) 2005 { 2006 unsigned char r1, r2; 2007 int i1, i2; 2008 2009 i1 = w1->w_index; 2010 i2 = w2->w_index; 2011 WITNESS_INDEX_ASSERT(i1); 2012 WITNESS_INDEX_ASSERT(i2); 2013 r1 = w_rmatrix[i1][i2] & WITNESS_RELATED_MASK; 2014 r2 = w_rmatrix[i2][i1] & WITNESS_RELATED_MASK; 2015 2016 /* The flags on one better be the inverse of the flags on the other */ 2017 if (!((WITNESS_ATOD(r1) == r2 && WITNESS_DTOA(r2) == r1) || 2018 (WITNESS_DTOA(r1) == r2 && WITNESS_ATOD(r2) == r1))) { 2019 /* Don't squawk if we're potentially racing with an update. */ 2020 if (!mtx_owned(&w_mtx)) 2021 return (0); 2022 printf("%s: rmatrix mismatch between %s (index %d) and %s " 2023 "(index %d): w_rmatrix[%d][%d] == %hhx but " 2024 "w_rmatrix[%d][%d] == %hhx\n", 2025 fname, w1->w_name, i1, w2->w_name, i2, i1, i2, r1, 2026 i2, i1, r2); 2027 kdb_backtrace(); 2028 printf("Witness disabled.\n"); 2029 witness_watch = -1; 2030 } 2031 return (r1 & rmask); 2032 } 2033 2034 /* 2035 * Checks if @child is a direct child of @parent. 2036 */ 2037 static int 2038 isitmychild(struct witness *parent, struct witness *child) 2039 { 2040 2041 return (_isitmyx(parent, child, WITNESS_PARENT, __func__)); 2042 } 2043 2044 /* 2045 * Checks if @descendant is a direct or inderect descendant of @ancestor. 2046 */ 2047 static int 2048 isitmydescendant(struct witness *ancestor, struct witness *descendant) 2049 { 2050 2051 return (_isitmyx(ancestor, descendant, WITNESS_ANCESTOR_MASK, 2052 __func__)); 2053 } 2054 2055 #ifdef BLESSING 2056 static int 2057 blessed(struct witness *w1, struct witness *w2) 2058 { 2059 int i; 2060 struct witness_blessed *b; 2061 2062 for (i = 0; i < blessed_count; i++) { 2063 b = &blessed_list[i]; 2064 if (strcmp(w1->w_name, b->b_lock1) == 0) { 2065 if (strcmp(w2->w_name, b->b_lock2) == 0) 2066 return (1); 2067 continue; 2068 } 2069 if (strcmp(w1->w_name, b->b_lock2) == 0) 2070 if (strcmp(w2->w_name, b->b_lock1) == 0) 2071 return (1); 2072 } 2073 return (0); 2074 } 2075 #endif 2076 2077 static struct witness * 2078 witness_get(void) 2079 { 2080 struct witness *w; 2081 int index; 2082 2083 if (witness_cold == 0) 2084 mtx_assert(&w_mtx, MA_OWNED); 2085 2086 if (witness_watch == -1) { 2087 mtx_unlock_spin(&w_mtx); 2088 return (NULL); 2089 } 2090 if (STAILQ_EMPTY(&w_free)) { 2091 witness_watch = -1; 2092 mtx_unlock_spin(&w_mtx); 2093 printf("WITNESS: unable to allocate a new witness object\n"); 2094 return (NULL); 2095 } 2096 w = STAILQ_FIRST(&w_free); 2097 STAILQ_REMOVE_HEAD(&w_free, w_list); 2098 w_free_cnt--; 2099 index = w->w_index; 2100 MPASS(index > 0 && index == w_max_used_index+1 && 2101 index < witness_count); 2102 bzero(w, sizeof(*w)); 2103 w->w_index = index; 2104 if (index > w_max_used_index) 2105 w_max_used_index = index; 2106 return (w); 2107 } 2108 2109 static void 2110 witness_free(struct witness *w) 2111 { 2112 2113 STAILQ_INSERT_HEAD(&w_free, w, w_list); 2114 w_free_cnt++; 2115 } 2116 2117 static struct lock_list_entry * 2118 witness_lock_list_get(void) 2119 { 2120 struct lock_list_entry *lle; 2121 2122 if (witness_watch == -1) 2123 return (NULL); 2124 mtx_lock_spin(&w_mtx); 2125 lle = w_lock_list_free; 2126 if (lle == NULL) { 2127 witness_watch = -1; 2128 mtx_unlock_spin(&w_mtx); 2129 printf("%s: witness exhausted\n", __func__); 2130 return (NULL); 2131 } 2132 w_lock_list_free = lle->ll_next; 2133 mtx_unlock_spin(&w_mtx); 2134 bzero(lle, sizeof(*lle)); 2135 return (lle); 2136 } 2137 2138 static void 2139 witness_lock_list_free(struct lock_list_entry *lle) 2140 { 2141 2142 mtx_lock_spin(&w_mtx); 2143 lle->ll_next = w_lock_list_free; 2144 w_lock_list_free = lle; 2145 mtx_unlock_spin(&w_mtx); 2146 } 2147 2148 static struct lock_instance * 2149 find_instance(struct lock_list_entry *list, const struct lock_object *lock) 2150 { 2151 struct lock_list_entry *lle; 2152 struct lock_instance *instance; 2153 int i; 2154 2155 for (lle = list; lle != NULL; lle = lle->ll_next) 2156 for (i = lle->ll_count - 1; i >= 0; i--) { 2157 instance = &lle->ll_children[i]; 2158 if (instance->li_lock == lock) 2159 return (instance); 2160 } 2161 return (NULL); 2162 } 2163 2164 static void 2165 witness_list_lock(struct lock_instance *instance, 2166 int (*prnt)(const char *fmt, ...)) 2167 { 2168 struct lock_object *lock; 2169 2170 lock = instance->li_lock; 2171 prnt("%s %s %s", (instance->li_flags & LI_EXCLUSIVE) != 0 ? 2172 "exclusive" : "shared", LOCK_CLASS(lock)->lc_name, lock->lo_name); 2173 if (lock->lo_witness->w_name != lock->lo_name) 2174 prnt(" (%s)", lock->lo_witness->w_name); 2175 prnt(" r = %d (%p) locked @ %s:%d\n", 2176 instance->li_flags & LI_RECURSEMASK, lock, 2177 fixup_filename(instance->li_file), instance->li_line); 2178 } 2179 2180 static int 2181 witness_output(const char *fmt, ...) 2182 { 2183 va_list ap; 2184 int ret; 2185 2186 va_start(ap, fmt); 2187 ret = witness_voutput(fmt, ap); 2188 va_end(ap); 2189 return (ret); 2190 } 2191 2192 static int 2193 witness_voutput(const char *fmt, va_list ap) 2194 { 2195 int ret; 2196 2197 ret = 0; 2198 switch (witness_channel) { 2199 case WITNESS_CONSOLE: 2200 ret = vprintf(fmt, ap); 2201 break; 2202 case WITNESS_LOG: 2203 vlog(LOG_NOTICE, fmt, ap); 2204 break; 2205 case WITNESS_NONE: 2206 break; 2207 } 2208 return (ret); 2209 } 2210 2211 #ifdef DDB 2212 static int 2213 witness_thread_has_locks(struct thread *td) 2214 { 2215 2216 if (td->td_sleeplocks == NULL) 2217 return (0); 2218 return (td->td_sleeplocks->ll_count != 0); 2219 } 2220 2221 static int 2222 witness_proc_has_locks(struct proc *p) 2223 { 2224 struct thread *td; 2225 2226 FOREACH_THREAD_IN_PROC(p, td) { 2227 if (witness_thread_has_locks(td)) 2228 return (1); 2229 } 2230 return (0); 2231 } 2232 #endif 2233 2234 int 2235 witness_list_locks(struct lock_list_entry **lock_list, 2236 int (*prnt)(const char *fmt, ...)) 2237 { 2238 struct lock_list_entry *lle; 2239 int i, nheld; 2240 2241 nheld = 0; 2242 for (lle = *lock_list; lle != NULL; lle = lle->ll_next) 2243 for (i = lle->ll_count - 1; i >= 0; i--) { 2244 witness_list_lock(&lle->ll_children[i], prnt); 2245 nheld++; 2246 } 2247 return (nheld); 2248 } 2249 2250 /* 2251 * This is a bit risky at best. We call this function when we have timed 2252 * out acquiring a spin lock, and we assume that the other CPU is stuck 2253 * with this lock held. So, we go groveling around in the other CPU's 2254 * per-cpu data to try to find the lock instance for this spin lock to 2255 * see when it was last acquired. 2256 */ 2257 void 2258 witness_display_spinlock(struct lock_object *lock, struct thread *owner, 2259 int (*prnt)(const char *fmt, ...)) 2260 { 2261 struct lock_instance *instance; 2262 struct pcpu *pc; 2263 2264 if (owner->td_critnest == 0 || owner->td_oncpu == NOCPU) 2265 return; 2266 pc = pcpu_find(owner->td_oncpu); 2267 instance = find_instance(pc->pc_spinlocks, lock); 2268 if (instance != NULL) 2269 witness_list_lock(instance, prnt); 2270 } 2271 2272 void 2273 witness_save(struct lock_object *lock, const char **filep, int *linep) 2274 { 2275 struct lock_list_entry *lock_list; 2276 struct lock_instance *instance; 2277 struct lock_class *class; 2278 2279 /* 2280 * This function is used independently in locking code to deal with 2281 * Giant, SCHEDULER_STOPPED() check can be removed here after Giant 2282 * is gone. 2283 */ 2284 if (SCHEDULER_STOPPED()) 2285 return; 2286 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); 2287 if (lock->lo_witness == NULL || witness_watch == -1 || panicstr != NULL) 2288 return; 2289 class = LOCK_CLASS(lock); 2290 if (class->lc_flags & LC_SLEEPLOCK) 2291 lock_list = curthread->td_sleeplocks; 2292 else { 2293 if (witness_skipspin) 2294 return; 2295 lock_list = PCPU_GET(spinlocks); 2296 } 2297 instance = find_instance(lock_list, lock); 2298 if (instance == NULL) { 2299 kassert_panic("%s: lock (%s) %s not locked", __func__, 2300 class->lc_name, lock->lo_name); 2301 return; 2302 } 2303 *filep = instance->li_file; 2304 *linep = instance->li_line; 2305 } 2306 2307 void 2308 witness_restore(struct lock_object *lock, const char *file, int line) 2309 { 2310 struct lock_list_entry *lock_list; 2311 struct lock_instance *instance; 2312 struct lock_class *class; 2313 2314 /* 2315 * This function is used independently in locking code to deal with 2316 * Giant, SCHEDULER_STOPPED() check can be removed here after Giant 2317 * is gone. 2318 */ 2319 if (SCHEDULER_STOPPED()) 2320 return; 2321 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); 2322 if (lock->lo_witness == NULL || witness_watch == -1 || panicstr != NULL) 2323 return; 2324 class = LOCK_CLASS(lock); 2325 if (class->lc_flags & LC_SLEEPLOCK) 2326 lock_list = curthread->td_sleeplocks; 2327 else { 2328 if (witness_skipspin) 2329 return; 2330 lock_list = PCPU_GET(spinlocks); 2331 } 2332 instance = find_instance(lock_list, lock); 2333 if (instance == NULL) 2334 kassert_panic("%s: lock (%s) %s not locked", __func__, 2335 class->lc_name, lock->lo_name); 2336 lock->lo_witness->w_file = file; 2337 lock->lo_witness->w_line = line; 2338 if (instance == NULL) 2339 return; 2340 instance->li_file = file; 2341 instance->li_line = line; 2342 } 2343 2344 void 2345 witness_assert(const struct lock_object *lock, int flags, const char *file, 2346 int line) 2347 { 2348 #ifdef INVARIANT_SUPPORT 2349 struct lock_instance *instance; 2350 struct lock_class *class; 2351 2352 if (lock->lo_witness == NULL || witness_watch < 1 || panicstr != NULL) 2353 return; 2354 class = LOCK_CLASS(lock); 2355 if ((class->lc_flags & LC_SLEEPLOCK) != 0) 2356 instance = find_instance(curthread->td_sleeplocks, lock); 2357 else if ((class->lc_flags & LC_SPINLOCK) != 0) 2358 instance = find_instance(PCPU_GET(spinlocks), lock); 2359 else { 2360 kassert_panic("Lock (%s) %s is not sleep or spin!", 2361 class->lc_name, lock->lo_name); 2362 return; 2363 } 2364 switch (flags) { 2365 case LA_UNLOCKED: 2366 if (instance != NULL) 2367 kassert_panic("Lock (%s) %s locked @ %s:%d.", 2368 class->lc_name, lock->lo_name, 2369 fixup_filename(file), line); 2370 break; 2371 case LA_LOCKED: 2372 case LA_LOCKED | LA_RECURSED: 2373 case LA_LOCKED | LA_NOTRECURSED: 2374 case LA_SLOCKED: 2375 case LA_SLOCKED | LA_RECURSED: 2376 case LA_SLOCKED | LA_NOTRECURSED: 2377 case LA_XLOCKED: 2378 case LA_XLOCKED | LA_RECURSED: 2379 case LA_XLOCKED | LA_NOTRECURSED: 2380 if (instance == NULL) { 2381 kassert_panic("Lock (%s) %s not locked @ %s:%d.", 2382 class->lc_name, lock->lo_name, 2383 fixup_filename(file), line); 2384 break; 2385 } 2386 if ((flags & LA_XLOCKED) != 0 && 2387 (instance->li_flags & LI_EXCLUSIVE) == 0) 2388 kassert_panic( 2389 "Lock (%s) %s not exclusively locked @ %s:%d.", 2390 class->lc_name, lock->lo_name, 2391 fixup_filename(file), line); 2392 if ((flags & LA_SLOCKED) != 0 && 2393 (instance->li_flags & LI_EXCLUSIVE) != 0) 2394 kassert_panic( 2395 "Lock (%s) %s exclusively locked @ %s:%d.", 2396 class->lc_name, lock->lo_name, 2397 fixup_filename(file), line); 2398 if ((flags & LA_RECURSED) != 0 && 2399 (instance->li_flags & LI_RECURSEMASK) == 0) 2400 kassert_panic("Lock (%s) %s not recursed @ %s:%d.", 2401 class->lc_name, lock->lo_name, 2402 fixup_filename(file), line); 2403 if ((flags & LA_NOTRECURSED) != 0 && 2404 (instance->li_flags & LI_RECURSEMASK) != 0) 2405 kassert_panic("Lock (%s) %s recursed @ %s:%d.", 2406 class->lc_name, lock->lo_name, 2407 fixup_filename(file), line); 2408 break; 2409 default: 2410 kassert_panic("Invalid lock assertion at %s:%d.", 2411 fixup_filename(file), line); 2412 2413 } 2414 #endif /* INVARIANT_SUPPORT */ 2415 } 2416 2417 static void 2418 witness_setflag(struct lock_object *lock, int flag, int set) 2419 { 2420 struct lock_list_entry *lock_list; 2421 struct lock_instance *instance; 2422 struct lock_class *class; 2423 2424 if (lock->lo_witness == NULL || witness_watch == -1 || panicstr != NULL) 2425 return; 2426 class = LOCK_CLASS(lock); 2427 if (class->lc_flags & LC_SLEEPLOCK) 2428 lock_list = curthread->td_sleeplocks; 2429 else { 2430 if (witness_skipspin) 2431 return; 2432 lock_list = PCPU_GET(spinlocks); 2433 } 2434 instance = find_instance(lock_list, lock); 2435 if (instance == NULL) { 2436 kassert_panic("%s: lock (%s) %s not locked", __func__, 2437 class->lc_name, lock->lo_name); 2438 return; 2439 } 2440 2441 if (set) 2442 instance->li_flags |= flag; 2443 else 2444 instance->li_flags &= ~flag; 2445 } 2446 2447 void 2448 witness_norelease(struct lock_object *lock) 2449 { 2450 2451 witness_setflag(lock, LI_NORELEASE, 1); 2452 } 2453 2454 void 2455 witness_releaseok(struct lock_object *lock) 2456 { 2457 2458 witness_setflag(lock, LI_NORELEASE, 0); 2459 } 2460 2461 #ifdef DDB 2462 static void 2463 witness_ddb_list(struct thread *td) 2464 { 2465 2466 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); 2467 KASSERT(kdb_active, ("%s: not in the debugger", __func__)); 2468 2469 if (witness_watch < 1) 2470 return; 2471 2472 witness_list_locks(&td->td_sleeplocks, db_printf); 2473 2474 /* 2475 * We only handle spinlocks if td == curthread. This is somewhat broken 2476 * if td is currently executing on some other CPU and holds spin locks 2477 * as we won't display those locks. If we had a MI way of getting 2478 * the per-cpu data for a given cpu then we could use 2479 * td->td_oncpu to get the list of spinlocks for this thread 2480 * and "fix" this. 2481 * 2482 * That still wouldn't really fix this unless we locked the scheduler 2483 * lock or stopped the other CPU to make sure it wasn't changing the 2484 * list out from under us. It is probably best to just not try to 2485 * handle threads on other CPU's for now. 2486 */ 2487 if (td == curthread && PCPU_GET(spinlocks) != NULL) 2488 witness_list_locks(PCPU_PTR(spinlocks), db_printf); 2489 } 2490 2491 DB_SHOW_COMMAND(locks, db_witness_list) 2492 { 2493 struct thread *td; 2494 2495 if (have_addr) 2496 td = db_lookup_thread(addr, true); 2497 else 2498 td = kdb_thread; 2499 witness_ddb_list(td); 2500 } 2501 2502 DB_SHOW_ALL_COMMAND(locks, db_witness_list_all) 2503 { 2504 struct thread *td; 2505 struct proc *p; 2506 2507 /* 2508 * It would be nice to list only threads and processes that actually 2509 * held sleep locks, but that information is currently not exported 2510 * by WITNESS. 2511 */ 2512 FOREACH_PROC_IN_SYSTEM(p) { 2513 if (!witness_proc_has_locks(p)) 2514 continue; 2515 FOREACH_THREAD_IN_PROC(p, td) { 2516 if (!witness_thread_has_locks(td)) 2517 continue; 2518 db_printf("Process %d (%s) thread %p (%d)\n", p->p_pid, 2519 p->p_comm, td, td->td_tid); 2520 witness_ddb_list(td); 2521 if (db_pager_quit) 2522 return; 2523 } 2524 } 2525 } 2526 DB_SHOW_ALIAS(alllocks, db_witness_list_all) 2527 2528 DB_SHOW_COMMAND(witness, db_witness_display) 2529 { 2530 2531 witness_ddb_display(db_printf); 2532 } 2533 #endif 2534 2535 static int 2536 sysctl_debug_witness_badstacks(SYSCTL_HANDLER_ARGS) 2537 { 2538 struct witness_lock_order_data *data1, *data2, *tmp_data1, *tmp_data2; 2539 struct witness *tmp_w1, *tmp_w2, *w1, *w2; 2540 struct sbuf *sb; 2541 u_int w_rmatrix1, w_rmatrix2; 2542 int error, generation, i, j; 2543 2544 tmp_data1 = NULL; 2545 tmp_data2 = NULL; 2546 tmp_w1 = NULL; 2547 tmp_w2 = NULL; 2548 if (witness_watch < 1) { 2549 error = SYSCTL_OUT(req, w_notrunning, sizeof(w_notrunning)); 2550 return (error); 2551 } 2552 if (witness_cold) { 2553 error = SYSCTL_OUT(req, w_stillcold, sizeof(w_stillcold)); 2554 return (error); 2555 } 2556 error = 0; 2557 sb = sbuf_new(NULL, NULL, badstack_sbuf_size, SBUF_AUTOEXTEND); 2558 if (sb == NULL) 2559 return (ENOMEM); 2560 2561 /* Allocate and init temporary storage space. */ 2562 tmp_w1 = malloc(sizeof(struct witness), M_TEMP, M_WAITOK | M_ZERO); 2563 tmp_w2 = malloc(sizeof(struct witness), M_TEMP, M_WAITOK | M_ZERO); 2564 tmp_data1 = malloc(sizeof(struct witness_lock_order_data), M_TEMP, 2565 M_WAITOK | M_ZERO); 2566 tmp_data2 = malloc(sizeof(struct witness_lock_order_data), M_TEMP, 2567 M_WAITOK | M_ZERO); 2568 stack_zero(&tmp_data1->wlod_stack); 2569 stack_zero(&tmp_data2->wlod_stack); 2570 2571 restart: 2572 mtx_lock_spin(&w_mtx); 2573 generation = w_generation; 2574 mtx_unlock_spin(&w_mtx); 2575 sbuf_printf(sb, "Number of known direct relationships is %d\n", 2576 w_lohash.wloh_count); 2577 for (i = 1; i < w_max_used_index; i++) { 2578 mtx_lock_spin(&w_mtx); 2579 if (generation != w_generation) { 2580 mtx_unlock_spin(&w_mtx); 2581 2582 /* The graph has changed, try again. */ 2583 req->oldidx = 0; 2584 sbuf_clear(sb); 2585 goto restart; 2586 } 2587 2588 w1 = &w_data[i]; 2589 if (w1->w_reversed == 0) { 2590 mtx_unlock_spin(&w_mtx); 2591 continue; 2592 } 2593 2594 /* Copy w1 locally so we can release the spin lock. */ 2595 *tmp_w1 = *w1; 2596 mtx_unlock_spin(&w_mtx); 2597 2598 if (tmp_w1->w_reversed == 0) 2599 continue; 2600 for (j = 1; j < w_max_used_index; j++) { 2601 if ((w_rmatrix[i][j] & WITNESS_REVERSAL) == 0 || i > j) 2602 continue; 2603 2604 mtx_lock_spin(&w_mtx); 2605 if (generation != w_generation) { 2606 mtx_unlock_spin(&w_mtx); 2607 2608 /* The graph has changed, try again. */ 2609 req->oldidx = 0; 2610 sbuf_clear(sb); 2611 goto restart; 2612 } 2613 2614 w2 = &w_data[j]; 2615 data1 = witness_lock_order_get(w1, w2); 2616 data2 = witness_lock_order_get(w2, w1); 2617 2618 /* 2619 * Copy information locally so we can release the 2620 * spin lock. 2621 */ 2622 *tmp_w2 = *w2; 2623 w_rmatrix1 = (unsigned int)w_rmatrix[i][j]; 2624 w_rmatrix2 = (unsigned int)w_rmatrix[j][i]; 2625 2626 if (data1) { 2627 stack_zero(&tmp_data1->wlod_stack); 2628 stack_copy(&data1->wlod_stack, 2629 &tmp_data1->wlod_stack); 2630 } 2631 if (data2 && data2 != data1) { 2632 stack_zero(&tmp_data2->wlod_stack); 2633 stack_copy(&data2->wlod_stack, 2634 &tmp_data2->wlod_stack); 2635 } 2636 mtx_unlock_spin(&w_mtx); 2637 2638 sbuf_printf(sb, 2639 "\nLock order reversal between \"%s\"(%s) and \"%s\"(%s)!\n", 2640 tmp_w1->w_name, tmp_w1->w_class->lc_name, 2641 tmp_w2->w_name, tmp_w2->w_class->lc_name); 2642 if (data1) { 2643 sbuf_printf(sb, 2644 "Lock order \"%s\"(%s) -> \"%s\"(%s) first seen at:\n", 2645 tmp_w1->w_name, tmp_w1->w_class->lc_name, 2646 tmp_w2->w_name, tmp_w2->w_class->lc_name); 2647 stack_sbuf_print(sb, &tmp_data1->wlod_stack); 2648 sbuf_printf(sb, "\n"); 2649 } 2650 if (data2 && data2 != data1) { 2651 sbuf_printf(sb, 2652 "Lock order \"%s\"(%s) -> \"%s\"(%s) first seen at:\n", 2653 tmp_w2->w_name, tmp_w2->w_class->lc_name, 2654 tmp_w1->w_name, tmp_w1->w_class->lc_name); 2655 stack_sbuf_print(sb, &tmp_data2->wlod_stack); 2656 sbuf_printf(sb, "\n"); 2657 } 2658 } 2659 } 2660 mtx_lock_spin(&w_mtx); 2661 if (generation != w_generation) { 2662 mtx_unlock_spin(&w_mtx); 2663 2664 /* 2665 * The graph changed while we were printing stack data, 2666 * try again. 2667 */ 2668 req->oldidx = 0; 2669 sbuf_clear(sb); 2670 goto restart; 2671 } 2672 mtx_unlock_spin(&w_mtx); 2673 2674 /* Free temporary storage space. */ 2675 free(tmp_data1, M_TEMP); 2676 free(tmp_data2, M_TEMP); 2677 free(tmp_w1, M_TEMP); 2678 free(tmp_w2, M_TEMP); 2679 2680 sbuf_finish(sb); 2681 error = SYSCTL_OUT(req, sbuf_data(sb), sbuf_len(sb) + 1); 2682 sbuf_delete(sb); 2683 2684 return (error); 2685 } 2686 2687 static int 2688 sysctl_debug_witness_channel(SYSCTL_HANDLER_ARGS) 2689 { 2690 static const struct { 2691 enum witness_channel channel; 2692 const char *name; 2693 } channels[] = { 2694 { WITNESS_CONSOLE, "console" }, 2695 { WITNESS_LOG, "log" }, 2696 { WITNESS_NONE, "none" }, 2697 }; 2698 char buf[16]; 2699 u_int i; 2700 int error; 2701 2702 buf[0] = '\0'; 2703 for (i = 0; i < nitems(channels); i++) 2704 if (witness_channel == channels[i].channel) { 2705 snprintf(buf, sizeof(buf), "%s", channels[i].name); 2706 break; 2707 } 2708 2709 error = sysctl_handle_string(oidp, buf, sizeof(buf), req); 2710 if (error != 0 || req->newptr == NULL) 2711 return (error); 2712 2713 error = EINVAL; 2714 for (i = 0; i < nitems(channels); i++) 2715 if (strcmp(channels[i].name, buf) == 0) { 2716 witness_channel = channels[i].channel; 2717 error = 0; 2718 break; 2719 } 2720 return (error); 2721 } 2722 2723 static int 2724 sysctl_debug_witness_fullgraph(SYSCTL_HANDLER_ARGS) 2725 { 2726 struct witness *w; 2727 struct sbuf *sb; 2728 int error; 2729 2730 if (witness_watch < 1) { 2731 error = SYSCTL_OUT(req, w_notrunning, sizeof(w_notrunning)); 2732 return (error); 2733 } 2734 if (witness_cold) { 2735 error = SYSCTL_OUT(req, w_stillcold, sizeof(w_stillcold)); 2736 return (error); 2737 } 2738 error = 0; 2739 2740 error = sysctl_wire_old_buffer(req, 0); 2741 if (error != 0) 2742 return (error); 2743 sb = sbuf_new_for_sysctl(NULL, NULL, FULLGRAPH_SBUF_SIZE, req); 2744 if (sb == NULL) 2745 return (ENOMEM); 2746 sbuf_printf(sb, "\n"); 2747 2748 mtx_lock_spin(&w_mtx); 2749 STAILQ_FOREACH(w, &w_all, w_list) 2750 w->w_displayed = 0; 2751 STAILQ_FOREACH(w, &w_all, w_list) 2752 witness_add_fullgraph(sb, w); 2753 mtx_unlock_spin(&w_mtx); 2754 2755 /* 2756 * Close the sbuf and return to userland. 2757 */ 2758 error = sbuf_finish(sb); 2759 sbuf_delete(sb); 2760 2761 return (error); 2762 } 2763 2764 static int 2765 sysctl_debug_witness_watch(SYSCTL_HANDLER_ARGS) 2766 { 2767 int error, value; 2768 2769 value = witness_watch; 2770 error = sysctl_handle_int(oidp, &value, 0, req); 2771 if (error != 0 || req->newptr == NULL) 2772 return (error); 2773 if (value > 1 || value < -1 || 2774 (witness_watch == -1 && value != witness_watch)) 2775 return (EINVAL); 2776 witness_watch = value; 2777 return (0); 2778 } 2779 2780 static void 2781 witness_add_fullgraph(struct sbuf *sb, struct witness *w) 2782 { 2783 int i; 2784 2785 if (w->w_displayed != 0 || (w->w_file == NULL && w->w_line == 0)) 2786 return; 2787 w->w_displayed = 1; 2788 2789 WITNESS_INDEX_ASSERT(w->w_index); 2790 for (i = 1; i <= w_max_used_index; i++) { 2791 if (w_rmatrix[w->w_index][i] & WITNESS_PARENT) { 2792 sbuf_printf(sb, "\"%s\",\"%s\"\n", w->w_name, 2793 w_data[i].w_name); 2794 witness_add_fullgraph(sb, &w_data[i]); 2795 } 2796 } 2797 } 2798 2799 /* 2800 * A simple hash function. Takes a key pointer and a key size. If size == 0, 2801 * interprets the key as a string and reads until the null 2802 * terminator. Otherwise, reads the first size bytes. Returns an unsigned 32-bit 2803 * hash value computed from the key. 2804 */ 2805 static uint32_t 2806 witness_hash_djb2(const uint8_t *key, uint32_t size) 2807 { 2808 unsigned int hash = 5381; 2809 int i; 2810 2811 /* hash = hash * 33 + key[i] */ 2812 if (size) 2813 for (i = 0; i < size; i++) 2814 hash = ((hash << 5) + hash) + (unsigned int)key[i]; 2815 else 2816 for (i = 0; key[i] != 0; i++) 2817 hash = ((hash << 5) + hash) + (unsigned int)key[i]; 2818 2819 return (hash); 2820 } 2821 2822 2823 /* 2824 * Initializes the two witness hash tables. Called exactly once from 2825 * witness_initialize(). 2826 */ 2827 static void 2828 witness_init_hash_tables(void) 2829 { 2830 int i; 2831 2832 MPASS(witness_cold); 2833 2834 /* Initialize the hash tables. */ 2835 for (i = 0; i < WITNESS_HASH_SIZE; i++) 2836 w_hash.wh_array[i] = NULL; 2837 2838 w_hash.wh_size = WITNESS_HASH_SIZE; 2839 w_hash.wh_count = 0; 2840 2841 /* Initialize the lock order data hash. */ 2842 w_lofree = NULL; 2843 for (i = 0; i < WITNESS_LO_DATA_COUNT; i++) { 2844 memset(&w_lodata[i], 0, sizeof(w_lodata[i])); 2845 w_lodata[i].wlod_next = w_lofree; 2846 w_lofree = &w_lodata[i]; 2847 } 2848 w_lohash.wloh_size = WITNESS_LO_HASH_SIZE; 2849 w_lohash.wloh_count = 0; 2850 for (i = 0; i < WITNESS_LO_HASH_SIZE; i++) 2851 w_lohash.wloh_array[i] = NULL; 2852 } 2853 2854 static struct witness * 2855 witness_hash_get(const char *key) 2856 { 2857 struct witness *w; 2858 uint32_t hash; 2859 2860 MPASS(key != NULL); 2861 if (witness_cold == 0) 2862 mtx_assert(&w_mtx, MA_OWNED); 2863 hash = witness_hash_djb2(key, 0) % w_hash.wh_size; 2864 w = w_hash.wh_array[hash]; 2865 while (w != NULL) { 2866 if (strcmp(w->w_name, key) == 0) 2867 goto out; 2868 w = w->w_hash_next; 2869 } 2870 2871 out: 2872 return (w); 2873 } 2874 2875 static void 2876 witness_hash_put(struct witness *w) 2877 { 2878 uint32_t hash; 2879 2880 MPASS(w != NULL); 2881 MPASS(w->w_name != NULL); 2882 if (witness_cold == 0) 2883 mtx_assert(&w_mtx, MA_OWNED); 2884 KASSERT(witness_hash_get(w->w_name) == NULL, 2885 ("%s: trying to add a hash entry that already exists!", __func__)); 2886 KASSERT(w->w_hash_next == NULL, 2887 ("%s: w->w_hash_next != NULL", __func__)); 2888 2889 hash = witness_hash_djb2(w->w_name, 0) % w_hash.wh_size; 2890 w->w_hash_next = w_hash.wh_array[hash]; 2891 w_hash.wh_array[hash] = w; 2892 w_hash.wh_count++; 2893 } 2894 2895 2896 static struct witness_lock_order_data * 2897 witness_lock_order_get(struct witness *parent, struct witness *child) 2898 { 2899 struct witness_lock_order_data *data = NULL; 2900 struct witness_lock_order_key key; 2901 unsigned int hash; 2902 2903 MPASS(parent != NULL && child != NULL); 2904 key.from = parent->w_index; 2905 key.to = child->w_index; 2906 WITNESS_INDEX_ASSERT(key.from); 2907 WITNESS_INDEX_ASSERT(key.to); 2908 if ((w_rmatrix[parent->w_index][child->w_index] 2909 & WITNESS_LOCK_ORDER_KNOWN) == 0) 2910 goto out; 2911 2912 hash = witness_hash_djb2((const char*)&key, 2913 sizeof(key)) % w_lohash.wloh_size; 2914 data = w_lohash.wloh_array[hash]; 2915 while (data != NULL) { 2916 if (witness_lock_order_key_equal(&data->wlod_key, &key)) 2917 break; 2918 data = data->wlod_next; 2919 } 2920 2921 out: 2922 return (data); 2923 } 2924 2925 /* 2926 * Verify that parent and child have a known relationship, are not the same, 2927 * and child is actually a child of parent. This is done without w_mtx 2928 * to avoid contention in the common case. 2929 */ 2930 static int 2931 witness_lock_order_check(struct witness *parent, struct witness *child) 2932 { 2933 2934 if (parent != child && 2935 w_rmatrix[parent->w_index][child->w_index] 2936 & WITNESS_LOCK_ORDER_KNOWN && 2937 isitmychild(parent, child)) 2938 return (1); 2939 2940 return (0); 2941 } 2942 2943 static int 2944 witness_lock_order_add(struct witness *parent, struct witness *child) 2945 { 2946 struct witness_lock_order_data *data = NULL; 2947 struct witness_lock_order_key key; 2948 unsigned int hash; 2949 2950 MPASS(parent != NULL && child != NULL); 2951 key.from = parent->w_index; 2952 key.to = child->w_index; 2953 WITNESS_INDEX_ASSERT(key.from); 2954 WITNESS_INDEX_ASSERT(key.to); 2955 if (w_rmatrix[parent->w_index][child->w_index] 2956 & WITNESS_LOCK_ORDER_KNOWN) 2957 return (1); 2958 2959 hash = witness_hash_djb2((const char*)&key, 2960 sizeof(key)) % w_lohash.wloh_size; 2961 w_rmatrix[parent->w_index][child->w_index] |= WITNESS_LOCK_ORDER_KNOWN; 2962 data = w_lofree; 2963 if (data == NULL) 2964 return (0); 2965 w_lofree = data->wlod_next; 2966 data->wlod_next = w_lohash.wloh_array[hash]; 2967 data->wlod_key = key; 2968 w_lohash.wloh_array[hash] = data; 2969 w_lohash.wloh_count++; 2970 stack_zero(&data->wlod_stack); 2971 stack_save(&data->wlod_stack); 2972 return (1); 2973 } 2974 2975 /* Call this whenver the structure of the witness graph changes. */ 2976 static void 2977 witness_increment_graph_generation(void) 2978 { 2979 2980 if (witness_cold == 0) 2981 mtx_assert(&w_mtx, MA_OWNED); 2982 w_generation++; 2983 } 2984 2985 static int 2986 witness_output_drain(void *arg __unused, const char *data, int len) 2987 { 2988 2989 witness_output("%.*s", len, data); 2990 return (len); 2991 } 2992 2993 static void 2994 witness_debugger(int cond, const char *msg) 2995 { 2996 char buf[32]; 2997 struct sbuf sb; 2998 struct stack st; 2999 3000 if (!cond) 3001 return; 3002 3003 if (witness_trace) { 3004 sbuf_new(&sb, buf, sizeof(buf), SBUF_FIXEDLEN); 3005 sbuf_set_drain(&sb, witness_output_drain, NULL); 3006 3007 stack_zero(&st); 3008 stack_save(&st); 3009 witness_output("stack backtrace:\n"); 3010 stack_sbuf_print_ddb(&sb, &st); 3011 3012 sbuf_finish(&sb); 3013 } 3014 3015 #ifdef KDB 3016 if (witness_kdb) 3017 kdb_enter(KDB_WHY_WITNESS, msg); 3018 #endif 3019 } 3020