1 /*- 2 * SPDX-License-Identifier: BSD-3-Clause 3 * 4 * Copyright (c) 2008 Isilon Systems, Inc. 5 * Copyright (c) 2008 Ilya Maykov <ivmaykov@gmail.com> 6 * Copyright (c) 1998 Berkeley Software Design, Inc. 7 * All rights reserved. 8 * 9 * Redistribution and use in source and binary forms, with or without 10 * modification, are permitted provided that the following conditions 11 * are met: 12 * 1. Redistributions of source code must retain the above copyright 13 * notice, this list of conditions and the following disclaimer. 14 * 2. Redistributions in binary form must reproduce the above copyright 15 * notice, this list of conditions and the following disclaimer in the 16 * documentation and/or other materials provided with the distribution. 17 * 3. Berkeley Software Design Inc's name may not be used to endorse or 18 * promote products derived from this software without specific prior 19 * written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY BERKELEY SOFTWARE DESIGN INC ``AS IS'' AND 22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24 * ARE DISCLAIMED. IN NO EVENT SHALL BERKELEY SOFTWARE DESIGN INC BE LIABLE 25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31 * SUCH DAMAGE. 32 * 33 * from BSDI $Id: mutex_witness.c,v 1.1.2.20 2000/04/27 03:10:27 cp Exp $ 34 * and BSDI $Id: synch_machdep.c,v 2.3.2.39 2000/04/27 03:10:25 cp Exp $ 35 */ 36 37 /* 38 * Implementation of the `witness' lock verifier. Originally implemented for 39 * mutexes in BSD/OS. Extended to handle generic lock objects and lock 40 * classes in FreeBSD. 41 */ 42 43 /* 44 * Main Entry: witness 45 * Pronunciation: 'wit-n&s 46 * Function: noun 47 * Etymology: Middle English witnesse, from Old English witnes knowledge, 48 * testimony, witness, from 2wit 49 * Date: before 12th century 50 * 1 : attestation of a fact or event : TESTIMONY 51 * 2 : one that gives evidence; specifically : one who testifies in 52 * a cause or before a judicial tribunal 53 * 3 : one asked to be present at a transaction so as to be able to 54 * testify to its having taken place 55 * 4 : one who has personal knowledge of something 56 * 5 a : something serving as evidence or proof : SIGN 57 * b : public affirmation by word or example of usually 58 * religious faith or conviction <the heroic witness to divine 59 * life -- Pilot> 60 * 6 capitalized : a member of the Jehovah's Witnesses 61 */ 62 63 /* 64 * Special rules concerning Giant and lock orders: 65 * 66 * 1) Giant must be acquired before any other mutexes. Stated another way, 67 * no other mutex may be held when Giant is acquired. 68 * 69 * 2) Giant must be released when blocking on a sleepable lock. 70 * 71 * This rule is less obvious, but is a result of Giant providing the same 72 * semantics as spl(). Basically, when a thread sleeps, it must release 73 * Giant. When a thread blocks on a sleepable lock, it sleeps. Hence rule 74 * 2). 75 * 76 * 3) Giant may be acquired before or after sleepable locks. 77 * 78 * This rule is also not quite as obvious. Giant may be acquired after 79 * a sleepable lock because it is a non-sleepable lock and non-sleepable 80 * locks may always be acquired while holding a sleepable lock. The second 81 * case, Giant before a sleepable lock, follows from rule 2) above. Suppose 82 * you have two threads T1 and T2 and a sleepable lock X. Suppose that T1 83 * acquires X and blocks on Giant. Then suppose that T2 acquires Giant and 84 * blocks on X. When T2 blocks on X, T2 will release Giant allowing T1 to 85 * execute. Thus, acquiring Giant both before and after a sleepable lock 86 * will not result in a lock order reversal. 87 */ 88 89 #include <sys/cdefs.h> 90 __FBSDID("$FreeBSD$"); 91 92 #include "opt_ddb.h" 93 #include "opt_hwpmc_hooks.h" 94 #include "opt_stack.h" 95 #include "opt_witness.h" 96 97 #include <sys/param.h> 98 #include <sys/bus.h> 99 #include <sys/kdb.h> 100 #include <sys/kernel.h> 101 #include <sys/ktr.h> 102 #include <sys/lock.h> 103 #include <sys/malloc.h> 104 #include <sys/mutex.h> 105 #include <sys/priv.h> 106 #include <sys/proc.h> 107 #include <sys/sbuf.h> 108 #include <sys/sched.h> 109 #include <sys/stack.h> 110 #include <sys/sysctl.h> 111 #include <sys/syslog.h> 112 #include <sys/systm.h> 113 114 #ifdef DDB 115 #include <ddb/ddb.h> 116 #endif 117 118 #include <machine/stdarg.h> 119 120 #if !defined(DDB) && !defined(STACK) 121 #error "DDB or STACK options are required for WITNESS" 122 #endif 123 124 /* Note that these traces do not work with KTR_ALQ. */ 125 #if 0 126 #define KTR_WITNESS KTR_SUBSYS 127 #else 128 #define KTR_WITNESS 0 129 #endif 130 131 #define LI_RECURSEMASK 0x0000ffff /* Recursion depth of lock instance. */ 132 #define LI_EXCLUSIVE 0x00010000 /* Exclusive lock instance. */ 133 #define LI_NORELEASE 0x00020000 /* Lock not allowed to be released. */ 134 135 /* Define this to check for blessed mutexes */ 136 #undef BLESSING 137 138 #ifndef WITNESS_COUNT 139 #define WITNESS_COUNT 1536 140 #endif 141 #define WITNESS_HASH_SIZE 251 /* Prime, gives load factor < 2 */ 142 #define WITNESS_PENDLIST (2048 + MAXCPU) 143 144 /* Allocate 256 KB of stack data space */ 145 #define WITNESS_LO_DATA_COUNT 2048 146 147 /* Prime, gives load factor of ~2 at full load */ 148 #define WITNESS_LO_HASH_SIZE 1021 149 150 /* 151 * XXX: This is somewhat bogus, as we assume here that at most 2048 threads 152 * will hold LOCK_NCHILDREN locks. We handle failure ok, and we should 153 * probably be safe for the most part, but it's still a SWAG. 154 */ 155 #define LOCK_NCHILDREN 5 156 #define LOCK_CHILDCOUNT 2048 157 158 #define MAX_W_NAME 64 159 160 #define FULLGRAPH_SBUF_SIZE 512 161 162 /* 163 * These flags go in the witness relationship matrix and describe the 164 * relationship between any two struct witness objects. 165 */ 166 #define WITNESS_UNRELATED 0x00 /* No lock order relation. */ 167 #define WITNESS_PARENT 0x01 /* Parent, aka direct ancestor. */ 168 #define WITNESS_ANCESTOR 0x02 /* Direct or indirect ancestor. */ 169 #define WITNESS_CHILD 0x04 /* Child, aka direct descendant. */ 170 #define WITNESS_DESCENDANT 0x08 /* Direct or indirect descendant. */ 171 #define WITNESS_ANCESTOR_MASK (WITNESS_PARENT | WITNESS_ANCESTOR) 172 #define WITNESS_DESCENDANT_MASK (WITNESS_CHILD | WITNESS_DESCENDANT) 173 #define WITNESS_RELATED_MASK \ 174 (WITNESS_ANCESTOR_MASK | WITNESS_DESCENDANT_MASK) 175 #define WITNESS_REVERSAL 0x10 /* A lock order reversal has been 176 * observed. */ 177 #define WITNESS_RESERVED1 0x20 /* Unused flag, reserved. */ 178 #define WITNESS_RESERVED2 0x40 /* Unused flag, reserved. */ 179 #define WITNESS_LOCK_ORDER_KNOWN 0x80 /* This lock order is known. */ 180 181 /* Descendant to ancestor flags */ 182 #define WITNESS_DTOA(x) (((x) & WITNESS_RELATED_MASK) >> 2) 183 184 /* Ancestor to descendant flags */ 185 #define WITNESS_ATOD(x) (((x) & WITNESS_RELATED_MASK) << 2) 186 187 #define WITNESS_INDEX_ASSERT(i) \ 188 MPASS((i) > 0 && (i) <= w_max_used_index && (i) < witness_count) 189 190 static MALLOC_DEFINE(M_WITNESS, "Witness", "Witness"); 191 192 /* 193 * Lock instances. A lock instance is the data associated with a lock while 194 * it is held by witness. For example, a lock instance will hold the 195 * recursion count of a lock. Lock instances are held in lists. Spin locks 196 * are held in a per-cpu list while sleep locks are held in per-thread list. 197 */ 198 struct lock_instance { 199 struct lock_object *li_lock; 200 const char *li_file; 201 int li_line; 202 u_int li_flags; 203 }; 204 205 /* 206 * A simple list type used to build the list of locks held by a thread 207 * or CPU. We can't simply embed the list in struct lock_object since a 208 * lock may be held by more than one thread if it is a shared lock. Locks 209 * are added to the head of the list, so we fill up each list entry from 210 * "the back" logically. To ease some of the arithmetic, we actually fill 211 * in each list entry the normal way (children[0] then children[1], etc.) but 212 * when we traverse the list we read children[count-1] as the first entry 213 * down to children[0] as the final entry. 214 */ 215 struct lock_list_entry { 216 struct lock_list_entry *ll_next; 217 struct lock_instance ll_children[LOCK_NCHILDREN]; 218 u_int ll_count; 219 }; 220 221 /* 222 * The main witness structure. One of these per named lock type in the system 223 * (for example, "vnode interlock"). 224 */ 225 struct witness { 226 char w_name[MAX_W_NAME]; 227 uint32_t w_index; /* Index in the relationship matrix */ 228 struct lock_class *w_class; 229 STAILQ_ENTRY(witness) w_list; /* List of all witnesses. */ 230 STAILQ_ENTRY(witness) w_typelist; /* Witnesses of a type. */ 231 struct witness *w_hash_next; /* Linked list in hash buckets. */ 232 const char *w_file; /* File where last acquired */ 233 uint32_t w_line; /* Line where last acquired */ 234 uint32_t w_refcount; 235 uint16_t w_num_ancestors; /* direct/indirect 236 * ancestor count */ 237 uint16_t w_num_descendants; /* direct/indirect 238 * descendant count */ 239 int16_t w_ddb_level; 240 unsigned w_displayed:1; 241 unsigned w_reversed:1; 242 }; 243 244 STAILQ_HEAD(witness_list, witness); 245 246 /* 247 * The witness hash table. Keys are witness names (const char *), elements are 248 * witness objects (struct witness *). 249 */ 250 struct witness_hash { 251 struct witness *wh_array[WITNESS_HASH_SIZE]; 252 uint32_t wh_size; 253 uint32_t wh_count; 254 }; 255 256 /* 257 * Key type for the lock order data hash table. 258 */ 259 struct witness_lock_order_key { 260 uint16_t from; 261 uint16_t to; 262 }; 263 264 struct witness_lock_order_data { 265 struct stack wlod_stack; 266 struct witness_lock_order_key wlod_key; 267 struct witness_lock_order_data *wlod_next; 268 }; 269 270 /* 271 * The witness lock order data hash table. Keys are witness index tuples 272 * (struct witness_lock_order_key), elements are lock order data objects 273 * (struct witness_lock_order_data). 274 */ 275 struct witness_lock_order_hash { 276 struct witness_lock_order_data *wloh_array[WITNESS_LO_HASH_SIZE]; 277 u_int wloh_size; 278 u_int wloh_count; 279 }; 280 281 #ifdef BLESSING 282 struct witness_blessed { 283 const char *b_lock1; 284 const char *b_lock2; 285 }; 286 #endif 287 288 struct witness_pendhelp { 289 const char *wh_type; 290 struct lock_object *wh_lock; 291 }; 292 293 struct witness_order_list_entry { 294 const char *w_name; 295 struct lock_class *w_class; 296 }; 297 298 /* 299 * Returns 0 if one of the locks is a spin lock and the other is not. 300 * Returns 1 otherwise. 301 */ 302 static __inline int 303 witness_lock_type_equal(struct witness *w1, struct witness *w2) 304 { 305 306 return ((w1->w_class->lc_flags & (LC_SLEEPLOCK | LC_SPINLOCK)) == 307 (w2->w_class->lc_flags & (LC_SLEEPLOCK | LC_SPINLOCK))); 308 } 309 310 static __inline int 311 witness_lock_order_key_equal(const struct witness_lock_order_key *a, 312 const struct witness_lock_order_key *b) 313 { 314 315 return (a->from == b->from && a->to == b->to); 316 } 317 318 static int _isitmyx(struct witness *w1, struct witness *w2, int rmask, 319 const char *fname); 320 static void adopt(struct witness *parent, struct witness *child); 321 #ifdef BLESSING 322 static int blessed(struct witness *, struct witness *); 323 #endif 324 static void depart(struct witness *w); 325 static struct witness *enroll(const char *description, 326 struct lock_class *lock_class); 327 static struct lock_instance *find_instance(struct lock_list_entry *list, 328 const struct lock_object *lock); 329 static int isitmychild(struct witness *parent, struct witness *child); 330 static int isitmydescendant(struct witness *parent, struct witness *child); 331 static void itismychild(struct witness *parent, struct witness *child); 332 static int sysctl_debug_witness_badstacks(SYSCTL_HANDLER_ARGS); 333 static int sysctl_debug_witness_watch(SYSCTL_HANDLER_ARGS); 334 static int sysctl_debug_witness_fullgraph(SYSCTL_HANDLER_ARGS); 335 static int sysctl_debug_witness_channel(SYSCTL_HANDLER_ARGS); 336 static void witness_add_fullgraph(struct sbuf *sb, struct witness *parent); 337 #ifdef DDB 338 static void witness_ddb_compute_levels(void); 339 static void witness_ddb_display(int(*)(const char *fmt, ...)); 340 static void witness_ddb_display_descendants(int(*)(const char *fmt, ...), 341 struct witness *, int indent); 342 static void witness_ddb_display_list(int(*prnt)(const char *fmt, ...), 343 struct witness_list *list); 344 static void witness_ddb_level_descendants(struct witness *parent, int l); 345 static void witness_ddb_list(struct thread *td); 346 #endif 347 static void witness_debugger(int cond, const char *msg); 348 static void witness_free(struct witness *m); 349 static struct witness *witness_get(void); 350 static uint32_t witness_hash_djb2(const uint8_t *key, uint32_t size); 351 static struct witness *witness_hash_get(const char *key); 352 static void witness_hash_put(struct witness *w); 353 static void witness_init_hash_tables(void); 354 static void witness_increment_graph_generation(void); 355 static void witness_lock_list_free(struct lock_list_entry *lle); 356 static struct lock_list_entry *witness_lock_list_get(void); 357 static int witness_lock_order_add(struct witness *parent, 358 struct witness *child); 359 static int witness_lock_order_check(struct witness *parent, 360 struct witness *child); 361 static struct witness_lock_order_data *witness_lock_order_get( 362 struct witness *parent, 363 struct witness *child); 364 static void witness_list_lock(struct lock_instance *instance, 365 int (*prnt)(const char *fmt, ...)); 366 static int witness_output(const char *fmt, ...) __printflike(1, 2); 367 static int witness_voutput(const char *fmt, va_list ap) __printflike(1, 0); 368 static void witness_setflag(struct lock_object *lock, int flag, int set); 369 370 static SYSCTL_NODE(_debug, OID_AUTO, witness, CTLFLAG_RW, NULL, 371 "Witness Locking"); 372 373 /* 374 * If set to 0, lock order checking is disabled. If set to -1, 375 * witness is completely disabled. Otherwise witness performs full 376 * lock order checking for all locks. At runtime, lock order checking 377 * may be toggled. However, witness cannot be reenabled once it is 378 * completely disabled. 379 */ 380 static int witness_watch = 1; 381 SYSCTL_PROC(_debug_witness, OID_AUTO, watch, CTLFLAG_RWTUN | CTLTYPE_INT, NULL, 0, 382 sysctl_debug_witness_watch, "I", "witness is watching lock operations"); 383 384 #ifdef KDB 385 /* 386 * When KDB is enabled and witness_kdb is 1, it will cause the system 387 * to drop into kdebug() when: 388 * - a lock hierarchy violation occurs 389 * - locks are held when going to sleep. 390 */ 391 #ifdef WITNESS_KDB 392 int witness_kdb = 1; 393 #else 394 int witness_kdb = 0; 395 #endif 396 SYSCTL_INT(_debug_witness, OID_AUTO, kdb, CTLFLAG_RWTUN, &witness_kdb, 0, ""); 397 #endif /* KDB */ 398 399 #if defined(DDB) || defined(KDB) 400 /* 401 * When DDB or KDB is enabled and witness_trace is 1, it will cause the system 402 * to print a stack trace: 403 * - a lock hierarchy violation occurs 404 * - locks are held when going to sleep. 405 */ 406 int witness_trace = 1; 407 SYSCTL_INT(_debug_witness, OID_AUTO, trace, CTLFLAG_RWTUN, &witness_trace, 0, ""); 408 #endif /* DDB || KDB */ 409 410 #ifdef WITNESS_SKIPSPIN 411 int witness_skipspin = 1; 412 #else 413 int witness_skipspin = 0; 414 #endif 415 SYSCTL_INT(_debug_witness, OID_AUTO, skipspin, CTLFLAG_RDTUN, &witness_skipspin, 0, ""); 416 417 int badstack_sbuf_size; 418 419 int witness_count = WITNESS_COUNT; 420 SYSCTL_INT(_debug_witness, OID_AUTO, witness_count, CTLFLAG_RDTUN, 421 &witness_count, 0, ""); 422 423 /* 424 * Output channel for witness messages. By default we print to the console. 425 */ 426 enum witness_channel { 427 WITNESS_CONSOLE, 428 WITNESS_LOG, 429 WITNESS_NONE, 430 }; 431 432 static enum witness_channel witness_channel = WITNESS_CONSOLE; 433 SYSCTL_PROC(_debug_witness, OID_AUTO, output_channel, CTLTYPE_STRING | 434 CTLFLAG_RWTUN, NULL, 0, sysctl_debug_witness_channel, "A", 435 "Output channel for warnings"); 436 437 /* 438 * Call this to print out the relations between locks. 439 */ 440 SYSCTL_PROC(_debug_witness, OID_AUTO, fullgraph, CTLTYPE_STRING | CTLFLAG_RD, 441 NULL, 0, sysctl_debug_witness_fullgraph, "A", "Show locks relation graphs"); 442 443 /* 444 * Call this to print out the witness faulty stacks. 445 */ 446 SYSCTL_PROC(_debug_witness, OID_AUTO, badstacks, CTLTYPE_STRING | CTLFLAG_RD, 447 NULL, 0, sysctl_debug_witness_badstacks, "A", "Show bad witness stacks"); 448 449 static struct mtx w_mtx; 450 451 /* w_list */ 452 static struct witness_list w_free = STAILQ_HEAD_INITIALIZER(w_free); 453 static struct witness_list w_all = STAILQ_HEAD_INITIALIZER(w_all); 454 455 /* w_typelist */ 456 static struct witness_list w_spin = STAILQ_HEAD_INITIALIZER(w_spin); 457 static struct witness_list w_sleep = STAILQ_HEAD_INITIALIZER(w_sleep); 458 459 /* lock list */ 460 static struct lock_list_entry *w_lock_list_free = NULL; 461 static struct witness_pendhelp pending_locks[WITNESS_PENDLIST]; 462 static u_int pending_cnt; 463 464 static int w_free_cnt, w_spin_cnt, w_sleep_cnt; 465 SYSCTL_INT(_debug_witness, OID_AUTO, free_cnt, CTLFLAG_RD, &w_free_cnt, 0, ""); 466 SYSCTL_INT(_debug_witness, OID_AUTO, spin_cnt, CTLFLAG_RD, &w_spin_cnt, 0, ""); 467 SYSCTL_INT(_debug_witness, OID_AUTO, sleep_cnt, CTLFLAG_RD, &w_sleep_cnt, 0, 468 ""); 469 470 static struct witness *w_data; 471 static uint8_t **w_rmatrix; 472 static struct lock_list_entry w_locklistdata[LOCK_CHILDCOUNT]; 473 static struct witness_hash w_hash; /* The witness hash table. */ 474 475 /* The lock order data hash */ 476 static struct witness_lock_order_data w_lodata[WITNESS_LO_DATA_COUNT]; 477 static struct witness_lock_order_data *w_lofree = NULL; 478 static struct witness_lock_order_hash w_lohash; 479 static int w_max_used_index = 0; 480 static unsigned int w_generation = 0; 481 static const char w_notrunning[] = "Witness not running\n"; 482 static const char w_stillcold[] = "Witness is still cold\n"; 483 484 485 static struct witness_order_list_entry order_lists[] = { 486 /* 487 * sx locks 488 */ 489 { "proctree", &lock_class_sx }, 490 { "allproc", &lock_class_sx }, 491 { "allprison", &lock_class_sx }, 492 { NULL, NULL }, 493 /* 494 * Various mutexes 495 */ 496 { "Giant", &lock_class_mtx_sleep }, 497 { "pipe mutex", &lock_class_mtx_sleep }, 498 { "sigio lock", &lock_class_mtx_sleep }, 499 { "process group", &lock_class_mtx_sleep }, 500 { "process lock", &lock_class_mtx_sleep }, 501 { "session", &lock_class_mtx_sleep }, 502 { "uidinfo hash", &lock_class_rw }, 503 #ifdef HWPMC_HOOKS 504 { "pmc-sleep", &lock_class_mtx_sleep }, 505 #endif 506 { "time lock", &lock_class_mtx_sleep }, 507 { NULL, NULL }, 508 /* 509 * umtx 510 */ 511 { "umtx lock", &lock_class_mtx_sleep }, 512 { NULL, NULL }, 513 /* 514 * Sockets 515 */ 516 { "accept", &lock_class_mtx_sleep }, 517 { "so_snd", &lock_class_mtx_sleep }, 518 { "so_rcv", &lock_class_mtx_sleep }, 519 { "sellck", &lock_class_mtx_sleep }, 520 { NULL, NULL }, 521 /* 522 * Routing 523 */ 524 { "so_rcv", &lock_class_mtx_sleep }, 525 { "radix node head", &lock_class_rw }, 526 { "rtentry", &lock_class_mtx_sleep }, 527 { "ifaddr", &lock_class_mtx_sleep }, 528 { NULL, NULL }, 529 /* 530 * IPv4 multicast: 531 * protocol locks before interface locks, after UDP locks. 532 */ 533 { "udpinp", &lock_class_rw }, 534 { "in_multi_mtx", &lock_class_mtx_sleep }, 535 { "igmp_mtx", &lock_class_mtx_sleep }, 536 { "if_addr_lock", &lock_class_rw }, 537 { NULL, NULL }, 538 /* 539 * IPv6 multicast: 540 * protocol locks before interface locks, after UDP locks. 541 */ 542 { "udpinp", &lock_class_rw }, 543 { "in6_multi_mtx", &lock_class_mtx_sleep }, 544 { "mld_mtx", &lock_class_mtx_sleep }, 545 { "if_addr_lock", &lock_class_rw }, 546 { NULL, NULL }, 547 /* 548 * UNIX Domain Sockets 549 */ 550 { "unp_link_rwlock", &lock_class_rw }, 551 { "unp_list_lock", &lock_class_mtx_sleep }, 552 { "unp", &lock_class_mtx_sleep }, 553 { "so_snd", &lock_class_mtx_sleep }, 554 { NULL, NULL }, 555 /* 556 * UDP/IP 557 */ 558 { "udp", &lock_class_rw }, 559 { "udpinp", &lock_class_rw }, 560 { "so_snd", &lock_class_mtx_sleep }, 561 { NULL, NULL }, 562 /* 563 * TCP/IP 564 */ 565 { "tcp", &lock_class_rw }, 566 { "tcpinp", &lock_class_rw }, 567 { "so_snd", &lock_class_mtx_sleep }, 568 { NULL, NULL }, 569 /* 570 * BPF 571 */ 572 { "bpf global lock", &lock_class_mtx_sleep }, 573 { "bpf interface lock", &lock_class_rw }, 574 { "bpf cdev lock", &lock_class_mtx_sleep }, 575 { NULL, NULL }, 576 /* 577 * NFS server 578 */ 579 { "nfsd_mtx", &lock_class_mtx_sleep }, 580 { "so_snd", &lock_class_mtx_sleep }, 581 { NULL, NULL }, 582 583 /* 584 * IEEE 802.11 585 */ 586 { "802.11 com lock", &lock_class_mtx_sleep}, 587 { NULL, NULL }, 588 /* 589 * Network drivers 590 */ 591 { "network driver", &lock_class_mtx_sleep}, 592 { NULL, NULL }, 593 594 /* 595 * Netgraph 596 */ 597 { "ng_node", &lock_class_mtx_sleep }, 598 { "ng_worklist", &lock_class_mtx_sleep }, 599 { NULL, NULL }, 600 /* 601 * CDEV 602 */ 603 { "vm map (system)", &lock_class_mtx_sleep }, 604 { "vm pagequeue", &lock_class_mtx_sleep }, 605 { "vnode interlock", &lock_class_mtx_sleep }, 606 { "cdev", &lock_class_mtx_sleep }, 607 { NULL, NULL }, 608 /* 609 * VM 610 */ 611 { "vm map (user)", &lock_class_sx }, 612 { "vm object", &lock_class_rw }, 613 { "vm page", &lock_class_mtx_sleep }, 614 { "vm pagequeue", &lock_class_mtx_sleep }, 615 { "pmap pv global", &lock_class_rw }, 616 { "pmap", &lock_class_mtx_sleep }, 617 { "pmap pv list", &lock_class_rw }, 618 { "vm page free queue", &lock_class_mtx_sleep }, 619 { NULL, NULL }, 620 /* 621 * kqueue/VFS interaction 622 */ 623 { "kqueue", &lock_class_mtx_sleep }, 624 { "struct mount mtx", &lock_class_mtx_sleep }, 625 { "vnode interlock", &lock_class_mtx_sleep }, 626 { NULL, NULL }, 627 /* 628 * VFS namecache 629 */ 630 { "ncvn", &lock_class_mtx_sleep }, 631 { "ncbuc", &lock_class_rw }, 632 { "vnode interlock", &lock_class_mtx_sleep }, 633 { "ncneg", &lock_class_mtx_sleep }, 634 { NULL, NULL }, 635 /* 636 * ZFS locking 637 */ 638 { "dn->dn_mtx", &lock_class_sx }, 639 { "dr->dt.di.dr_mtx", &lock_class_sx }, 640 { "db->db_mtx", &lock_class_sx }, 641 { NULL, NULL }, 642 /* 643 * spin locks 644 */ 645 #ifdef SMP 646 { "ap boot", &lock_class_mtx_spin }, 647 #endif 648 { "rm.mutex_mtx", &lock_class_mtx_spin }, 649 { "sio", &lock_class_mtx_spin }, 650 #ifdef __i386__ 651 { "cy", &lock_class_mtx_spin }, 652 #endif 653 #ifdef __sparc64__ 654 { "pcib_mtx", &lock_class_mtx_spin }, 655 { "rtc_mtx", &lock_class_mtx_spin }, 656 #endif 657 { "scc_hwmtx", &lock_class_mtx_spin }, 658 { "uart_hwmtx", &lock_class_mtx_spin }, 659 { "fast_taskqueue", &lock_class_mtx_spin }, 660 { "intr table", &lock_class_mtx_spin }, 661 #ifdef HWPMC_HOOKS 662 { "pmc-per-proc", &lock_class_mtx_spin }, 663 #endif 664 { "process slock", &lock_class_mtx_spin }, 665 { "syscons video lock", &lock_class_mtx_spin }, 666 { "sleepq chain", &lock_class_mtx_spin }, 667 { "rm_spinlock", &lock_class_mtx_spin }, 668 { "turnstile chain", &lock_class_mtx_spin }, 669 { "turnstile lock", &lock_class_mtx_spin }, 670 { "sched lock", &lock_class_mtx_spin }, 671 { "td_contested", &lock_class_mtx_spin }, 672 { "callout", &lock_class_mtx_spin }, 673 { "entropy harvest mutex", &lock_class_mtx_spin }, 674 #ifdef SMP 675 { "smp rendezvous", &lock_class_mtx_spin }, 676 #endif 677 #ifdef __powerpc__ 678 { "tlb0", &lock_class_mtx_spin }, 679 #endif 680 /* 681 * leaf locks 682 */ 683 { "intrcnt", &lock_class_mtx_spin }, 684 { "icu", &lock_class_mtx_spin }, 685 #if defined(SMP) && defined(__sparc64__) 686 { "ipi", &lock_class_mtx_spin }, 687 #endif 688 #ifdef __i386__ 689 { "allpmaps", &lock_class_mtx_spin }, 690 { "descriptor tables", &lock_class_mtx_spin }, 691 #endif 692 { "clk", &lock_class_mtx_spin }, 693 { "cpuset", &lock_class_mtx_spin }, 694 { "mprof lock", &lock_class_mtx_spin }, 695 { "zombie lock", &lock_class_mtx_spin }, 696 { "ALD Queue", &lock_class_mtx_spin }, 697 #if defined(__i386__) || defined(__amd64__) 698 { "pcicfg", &lock_class_mtx_spin }, 699 { "NDIS thread lock", &lock_class_mtx_spin }, 700 #endif 701 { "tw_osl_io_lock", &lock_class_mtx_spin }, 702 { "tw_osl_q_lock", &lock_class_mtx_spin }, 703 { "tw_cl_io_lock", &lock_class_mtx_spin }, 704 { "tw_cl_intr_lock", &lock_class_mtx_spin }, 705 { "tw_cl_gen_lock", &lock_class_mtx_spin }, 706 #ifdef HWPMC_HOOKS 707 { "pmc-leaf", &lock_class_mtx_spin }, 708 #endif 709 { "blocked lock", &lock_class_mtx_spin }, 710 { NULL, NULL }, 711 { NULL, NULL } 712 }; 713 714 #ifdef BLESSING 715 /* 716 * Pairs of locks which have been blessed 717 * Don't complain about order problems with blessed locks 718 */ 719 static struct witness_blessed blessed_list[] = { 720 }; 721 #endif 722 723 /* 724 * This global is set to 0 once it becomes safe to use the witness code. 725 */ 726 static int witness_cold = 1; 727 728 /* 729 * This global is set to 1 once the static lock orders have been enrolled 730 * so that a warning can be issued for any spin locks enrolled later. 731 */ 732 static int witness_spin_warn = 0; 733 734 /* Trim useless garbage from filenames. */ 735 static const char * 736 fixup_filename(const char *file) 737 { 738 739 if (file == NULL) 740 return (NULL); 741 while (strncmp(file, "../", 3) == 0) 742 file += 3; 743 return (file); 744 } 745 746 /* 747 * The WITNESS-enabled diagnostic code. Note that the witness code does 748 * assume that the early boot is single-threaded at least until after this 749 * routine is completed. 750 */ 751 static void 752 witness_initialize(void *dummy __unused) 753 { 754 struct lock_object *lock; 755 struct witness_order_list_entry *order; 756 struct witness *w, *w1; 757 int i; 758 759 w_data = malloc(sizeof (struct witness) * witness_count, M_WITNESS, 760 M_WAITOK | M_ZERO); 761 762 w_rmatrix = malloc(sizeof(*w_rmatrix) * (witness_count + 1), 763 M_WITNESS, M_WAITOK | M_ZERO); 764 765 for (i = 0; i < witness_count + 1; i++) { 766 w_rmatrix[i] = malloc(sizeof(*w_rmatrix[i]) * 767 (witness_count + 1), M_WITNESS, M_WAITOK | M_ZERO); 768 } 769 badstack_sbuf_size = witness_count * 256; 770 771 /* 772 * We have to release Giant before initializing its witness 773 * structure so that WITNESS doesn't get confused. 774 */ 775 mtx_unlock(&Giant); 776 mtx_assert(&Giant, MA_NOTOWNED); 777 778 CTR1(KTR_WITNESS, "%s: initializing witness", __func__); 779 mtx_init(&w_mtx, "witness lock", NULL, MTX_SPIN | MTX_QUIET | 780 MTX_NOWITNESS | MTX_NOPROFILE); 781 for (i = witness_count - 1; i >= 0; i--) { 782 w = &w_data[i]; 783 memset(w, 0, sizeof(*w)); 784 w_data[i].w_index = i; /* Witness index never changes. */ 785 witness_free(w); 786 } 787 KASSERT(STAILQ_FIRST(&w_free)->w_index == 0, 788 ("%s: Invalid list of free witness objects", __func__)); 789 790 /* Witness with index 0 is not used to aid in debugging. */ 791 STAILQ_REMOVE_HEAD(&w_free, w_list); 792 w_free_cnt--; 793 794 for (i = 0; i < witness_count; i++) { 795 memset(w_rmatrix[i], 0, sizeof(*w_rmatrix[i]) * 796 (witness_count + 1)); 797 } 798 799 for (i = 0; i < LOCK_CHILDCOUNT; i++) 800 witness_lock_list_free(&w_locklistdata[i]); 801 witness_init_hash_tables(); 802 803 /* First add in all the specified order lists. */ 804 for (order = order_lists; order->w_name != NULL; order++) { 805 w = enroll(order->w_name, order->w_class); 806 if (w == NULL) 807 continue; 808 w->w_file = "order list"; 809 for (order++; order->w_name != NULL; order++) { 810 w1 = enroll(order->w_name, order->w_class); 811 if (w1 == NULL) 812 continue; 813 w1->w_file = "order list"; 814 itismychild(w, w1); 815 w = w1; 816 } 817 } 818 witness_spin_warn = 1; 819 820 /* Iterate through all locks and add them to witness. */ 821 for (i = 0; pending_locks[i].wh_lock != NULL; i++) { 822 lock = pending_locks[i].wh_lock; 823 KASSERT(lock->lo_flags & LO_WITNESS, 824 ("%s: lock %s is on pending list but not LO_WITNESS", 825 __func__, lock->lo_name)); 826 lock->lo_witness = enroll(pending_locks[i].wh_type, 827 LOCK_CLASS(lock)); 828 } 829 830 /* Mark the witness code as being ready for use. */ 831 witness_cold = 0; 832 833 mtx_lock(&Giant); 834 } 835 SYSINIT(witness_init, SI_SUB_WITNESS, SI_ORDER_FIRST, witness_initialize, 836 NULL); 837 838 void 839 witness_init(struct lock_object *lock, const char *type) 840 { 841 struct lock_class *class; 842 843 /* Various sanity checks. */ 844 class = LOCK_CLASS(lock); 845 if ((lock->lo_flags & LO_RECURSABLE) != 0 && 846 (class->lc_flags & LC_RECURSABLE) == 0) 847 kassert_panic("%s: lock (%s) %s can not be recursable", 848 __func__, class->lc_name, lock->lo_name); 849 if ((lock->lo_flags & LO_SLEEPABLE) != 0 && 850 (class->lc_flags & LC_SLEEPABLE) == 0) 851 kassert_panic("%s: lock (%s) %s can not be sleepable", 852 __func__, class->lc_name, lock->lo_name); 853 if ((lock->lo_flags & LO_UPGRADABLE) != 0 && 854 (class->lc_flags & LC_UPGRADABLE) == 0) 855 kassert_panic("%s: lock (%s) %s can not be upgradable", 856 __func__, class->lc_name, lock->lo_name); 857 858 /* 859 * If we shouldn't watch this lock, then just clear lo_witness. 860 * Otherwise, if witness_cold is set, then it is too early to 861 * enroll this lock, so defer it to witness_initialize() by adding 862 * it to the pending_locks list. If it is not too early, then enroll 863 * the lock now. 864 */ 865 if (witness_watch < 1 || panicstr != NULL || 866 (lock->lo_flags & LO_WITNESS) == 0) 867 lock->lo_witness = NULL; 868 else if (witness_cold) { 869 pending_locks[pending_cnt].wh_lock = lock; 870 pending_locks[pending_cnt++].wh_type = type; 871 if (pending_cnt > WITNESS_PENDLIST) 872 panic("%s: pending locks list is too small, " 873 "increase WITNESS_PENDLIST\n", 874 __func__); 875 } else 876 lock->lo_witness = enroll(type, class); 877 } 878 879 void 880 witness_destroy(struct lock_object *lock) 881 { 882 struct lock_class *class; 883 struct witness *w; 884 885 class = LOCK_CLASS(lock); 886 887 if (witness_cold) 888 panic("lock (%s) %s destroyed while witness_cold", 889 class->lc_name, lock->lo_name); 890 891 /* XXX: need to verify that no one holds the lock */ 892 if ((lock->lo_flags & LO_WITNESS) == 0 || lock->lo_witness == NULL) 893 return; 894 w = lock->lo_witness; 895 896 mtx_lock_spin(&w_mtx); 897 MPASS(w->w_refcount > 0); 898 w->w_refcount--; 899 900 if (w->w_refcount == 0) 901 depart(w); 902 mtx_unlock_spin(&w_mtx); 903 } 904 905 #ifdef DDB 906 static void 907 witness_ddb_compute_levels(void) 908 { 909 struct witness *w; 910 911 /* 912 * First clear all levels. 913 */ 914 STAILQ_FOREACH(w, &w_all, w_list) 915 w->w_ddb_level = -1; 916 917 /* 918 * Look for locks with no parents and level all their descendants. 919 */ 920 STAILQ_FOREACH(w, &w_all, w_list) { 921 922 /* If the witness has ancestors (is not a root), skip it. */ 923 if (w->w_num_ancestors > 0) 924 continue; 925 witness_ddb_level_descendants(w, 0); 926 } 927 } 928 929 static void 930 witness_ddb_level_descendants(struct witness *w, int l) 931 { 932 int i; 933 934 if (w->w_ddb_level >= l) 935 return; 936 937 w->w_ddb_level = l; 938 l++; 939 940 for (i = 1; i <= w_max_used_index; i++) { 941 if (w_rmatrix[w->w_index][i] & WITNESS_PARENT) 942 witness_ddb_level_descendants(&w_data[i], l); 943 } 944 } 945 946 static void 947 witness_ddb_display_descendants(int(*prnt)(const char *fmt, ...), 948 struct witness *w, int indent) 949 { 950 int i; 951 952 for (i = 0; i < indent; i++) 953 prnt(" "); 954 prnt("%s (type: %s, depth: %d, active refs: %d)", 955 w->w_name, w->w_class->lc_name, 956 w->w_ddb_level, w->w_refcount); 957 if (w->w_displayed) { 958 prnt(" -- (already displayed)\n"); 959 return; 960 } 961 w->w_displayed = 1; 962 if (w->w_file != NULL && w->w_line != 0) 963 prnt(" -- last acquired @ %s:%d\n", fixup_filename(w->w_file), 964 w->w_line); 965 else 966 prnt(" -- never acquired\n"); 967 indent++; 968 WITNESS_INDEX_ASSERT(w->w_index); 969 for (i = 1; i <= w_max_used_index; i++) { 970 if (db_pager_quit) 971 return; 972 if (w_rmatrix[w->w_index][i] & WITNESS_PARENT) 973 witness_ddb_display_descendants(prnt, &w_data[i], 974 indent); 975 } 976 } 977 978 static void 979 witness_ddb_display_list(int(*prnt)(const char *fmt, ...), 980 struct witness_list *list) 981 { 982 struct witness *w; 983 984 STAILQ_FOREACH(w, list, w_typelist) { 985 if (w->w_file == NULL || w->w_ddb_level > 0) 986 continue; 987 988 /* This lock has no anscestors - display its descendants. */ 989 witness_ddb_display_descendants(prnt, w, 0); 990 if (db_pager_quit) 991 return; 992 } 993 } 994 995 static void 996 witness_ddb_display(int(*prnt)(const char *fmt, ...)) 997 { 998 struct witness *w; 999 1000 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); 1001 witness_ddb_compute_levels(); 1002 1003 /* Clear all the displayed flags. */ 1004 STAILQ_FOREACH(w, &w_all, w_list) 1005 w->w_displayed = 0; 1006 1007 /* 1008 * First, handle sleep locks which have been acquired at least 1009 * once. 1010 */ 1011 prnt("Sleep locks:\n"); 1012 witness_ddb_display_list(prnt, &w_sleep); 1013 if (db_pager_quit) 1014 return; 1015 1016 /* 1017 * Now do spin locks which have been acquired at least once. 1018 */ 1019 prnt("\nSpin locks:\n"); 1020 witness_ddb_display_list(prnt, &w_spin); 1021 if (db_pager_quit) 1022 return; 1023 1024 /* 1025 * Finally, any locks which have not been acquired yet. 1026 */ 1027 prnt("\nLocks which were never acquired:\n"); 1028 STAILQ_FOREACH(w, &w_all, w_list) { 1029 if (w->w_file != NULL || w->w_refcount == 0) 1030 continue; 1031 prnt("%s (type: %s, depth: %d)\n", w->w_name, 1032 w->w_class->lc_name, w->w_ddb_level); 1033 if (db_pager_quit) 1034 return; 1035 } 1036 } 1037 #endif /* DDB */ 1038 1039 int 1040 witness_defineorder(struct lock_object *lock1, struct lock_object *lock2) 1041 { 1042 1043 if (witness_watch == -1 || panicstr != NULL) 1044 return (0); 1045 1046 /* Require locks that witness knows about. */ 1047 if (lock1 == NULL || lock1->lo_witness == NULL || lock2 == NULL || 1048 lock2->lo_witness == NULL) 1049 return (EINVAL); 1050 1051 mtx_assert(&w_mtx, MA_NOTOWNED); 1052 mtx_lock_spin(&w_mtx); 1053 1054 /* 1055 * If we already have either an explicit or implied lock order that 1056 * is the other way around, then return an error. 1057 */ 1058 if (witness_watch && 1059 isitmydescendant(lock2->lo_witness, lock1->lo_witness)) { 1060 mtx_unlock_spin(&w_mtx); 1061 return (EDOOFUS); 1062 } 1063 1064 /* Try to add the new order. */ 1065 CTR3(KTR_WITNESS, "%s: adding %s as a child of %s", __func__, 1066 lock2->lo_witness->w_name, lock1->lo_witness->w_name); 1067 itismychild(lock1->lo_witness, lock2->lo_witness); 1068 mtx_unlock_spin(&w_mtx); 1069 return (0); 1070 } 1071 1072 void 1073 witness_checkorder(struct lock_object *lock, int flags, const char *file, 1074 int line, struct lock_object *interlock) 1075 { 1076 struct lock_list_entry *lock_list, *lle; 1077 struct lock_instance *lock1, *lock2, *plock; 1078 struct lock_class *class, *iclass; 1079 struct witness *w, *w1; 1080 struct thread *td; 1081 int i, j; 1082 1083 if (witness_cold || witness_watch < 1 || lock->lo_witness == NULL || 1084 panicstr != NULL) 1085 return; 1086 1087 w = lock->lo_witness; 1088 class = LOCK_CLASS(lock); 1089 td = curthread; 1090 1091 if (class->lc_flags & LC_SLEEPLOCK) { 1092 1093 /* 1094 * Since spin locks include a critical section, this check 1095 * implicitly enforces a lock order of all sleep locks before 1096 * all spin locks. 1097 */ 1098 if (td->td_critnest != 0 && !kdb_active) 1099 kassert_panic("acquiring blockable sleep lock with " 1100 "spinlock or critical section held (%s) %s @ %s:%d", 1101 class->lc_name, lock->lo_name, 1102 fixup_filename(file), line); 1103 1104 /* 1105 * If this is the first lock acquired then just return as 1106 * no order checking is needed. 1107 */ 1108 lock_list = td->td_sleeplocks; 1109 if (lock_list == NULL || lock_list->ll_count == 0) 1110 return; 1111 } else { 1112 1113 /* 1114 * If this is the first lock, just return as no order 1115 * checking is needed. Avoid problems with thread 1116 * migration pinning the thread while checking if 1117 * spinlocks are held. If at least one spinlock is held 1118 * the thread is in a safe path and it is allowed to 1119 * unpin it. 1120 */ 1121 sched_pin(); 1122 lock_list = PCPU_GET(spinlocks); 1123 if (lock_list == NULL || lock_list->ll_count == 0) { 1124 sched_unpin(); 1125 return; 1126 } 1127 sched_unpin(); 1128 } 1129 1130 /* 1131 * Check to see if we are recursing on a lock we already own. If 1132 * so, make sure that we don't mismatch exclusive and shared lock 1133 * acquires. 1134 */ 1135 lock1 = find_instance(lock_list, lock); 1136 if (lock1 != NULL) { 1137 if ((lock1->li_flags & LI_EXCLUSIVE) != 0 && 1138 (flags & LOP_EXCLUSIVE) == 0) { 1139 witness_output("shared lock of (%s) %s @ %s:%d\n", 1140 class->lc_name, lock->lo_name, 1141 fixup_filename(file), line); 1142 witness_output("while exclusively locked from %s:%d\n", 1143 fixup_filename(lock1->li_file), lock1->li_line); 1144 kassert_panic("excl->share"); 1145 } 1146 if ((lock1->li_flags & LI_EXCLUSIVE) == 0 && 1147 (flags & LOP_EXCLUSIVE) != 0) { 1148 witness_output("exclusive lock of (%s) %s @ %s:%d\n", 1149 class->lc_name, lock->lo_name, 1150 fixup_filename(file), line); 1151 witness_output("while share locked from %s:%d\n", 1152 fixup_filename(lock1->li_file), lock1->li_line); 1153 kassert_panic("share->excl"); 1154 } 1155 return; 1156 } 1157 1158 /* Warn if the interlock is not locked exactly once. */ 1159 if (interlock != NULL) { 1160 iclass = LOCK_CLASS(interlock); 1161 lock1 = find_instance(lock_list, interlock); 1162 if (lock1 == NULL) 1163 kassert_panic("interlock (%s) %s not locked @ %s:%d", 1164 iclass->lc_name, interlock->lo_name, 1165 fixup_filename(file), line); 1166 else if ((lock1->li_flags & LI_RECURSEMASK) != 0) 1167 kassert_panic("interlock (%s) %s recursed @ %s:%d", 1168 iclass->lc_name, interlock->lo_name, 1169 fixup_filename(file), line); 1170 } 1171 1172 /* 1173 * Find the previously acquired lock, but ignore interlocks. 1174 */ 1175 plock = &lock_list->ll_children[lock_list->ll_count - 1]; 1176 if (interlock != NULL && plock->li_lock == interlock) { 1177 if (lock_list->ll_count > 1) 1178 plock = 1179 &lock_list->ll_children[lock_list->ll_count - 2]; 1180 else { 1181 lle = lock_list->ll_next; 1182 1183 /* 1184 * The interlock is the only lock we hold, so 1185 * simply return. 1186 */ 1187 if (lle == NULL) 1188 return; 1189 plock = &lle->ll_children[lle->ll_count - 1]; 1190 } 1191 } 1192 1193 /* 1194 * Try to perform most checks without a lock. If this succeeds we 1195 * can skip acquiring the lock and return success. Otherwise we redo 1196 * the check with the lock held to handle races with concurrent updates. 1197 */ 1198 w1 = plock->li_lock->lo_witness; 1199 if (witness_lock_order_check(w1, w)) 1200 return; 1201 1202 mtx_lock_spin(&w_mtx); 1203 if (witness_lock_order_check(w1, w)) { 1204 mtx_unlock_spin(&w_mtx); 1205 return; 1206 } 1207 witness_lock_order_add(w1, w); 1208 1209 /* 1210 * Check for duplicate locks of the same type. Note that we only 1211 * have to check for this on the last lock we just acquired. Any 1212 * other cases will be caught as lock order violations. 1213 */ 1214 if (w1 == w) { 1215 i = w->w_index; 1216 if (!(lock->lo_flags & LO_DUPOK) && !(flags & LOP_DUPOK) && 1217 !(w_rmatrix[i][i] & WITNESS_REVERSAL)) { 1218 w_rmatrix[i][i] |= WITNESS_REVERSAL; 1219 w->w_reversed = 1; 1220 mtx_unlock_spin(&w_mtx); 1221 witness_output( 1222 "acquiring duplicate lock of same type: \"%s\"\n", 1223 w->w_name); 1224 witness_output(" 1st %s @ %s:%d\n", plock->li_lock->lo_name, 1225 fixup_filename(plock->li_file), plock->li_line); 1226 witness_output(" 2nd %s @ %s:%d\n", lock->lo_name, 1227 fixup_filename(file), line); 1228 witness_debugger(1, __func__); 1229 } else 1230 mtx_unlock_spin(&w_mtx); 1231 return; 1232 } 1233 mtx_assert(&w_mtx, MA_OWNED); 1234 1235 /* 1236 * If we know that the lock we are acquiring comes after 1237 * the lock we most recently acquired in the lock order tree, 1238 * then there is no need for any further checks. 1239 */ 1240 if (isitmychild(w1, w)) 1241 goto out; 1242 1243 for (j = 0, lle = lock_list; lle != NULL; lle = lle->ll_next) { 1244 for (i = lle->ll_count - 1; i >= 0; i--, j++) { 1245 1246 MPASS(j < LOCK_CHILDCOUNT * LOCK_NCHILDREN); 1247 lock1 = &lle->ll_children[i]; 1248 1249 /* 1250 * Ignore the interlock. 1251 */ 1252 if (interlock == lock1->li_lock) 1253 continue; 1254 1255 /* 1256 * If this lock doesn't undergo witness checking, 1257 * then skip it. 1258 */ 1259 w1 = lock1->li_lock->lo_witness; 1260 if (w1 == NULL) { 1261 KASSERT((lock1->li_lock->lo_flags & LO_WITNESS) == 0, 1262 ("lock missing witness structure")); 1263 continue; 1264 } 1265 1266 /* 1267 * If we are locking Giant and this is a sleepable 1268 * lock, then skip it. 1269 */ 1270 if ((lock1->li_lock->lo_flags & LO_SLEEPABLE) != 0 && 1271 lock == &Giant.lock_object) 1272 continue; 1273 1274 /* 1275 * If we are locking a sleepable lock and this lock 1276 * is Giant, then skip it. 1277 */ 1278 if ((lock->lo_flags & LO_SLEEPABLE) != 0 && 1279 lock1->li_lock == &Giant.lock_object) 1280 continue; 1281 1282 /* 1283 * If we are locking a sleepable lock and this lock 1284 * isn't sleepable, we want to treat it as a lock 1285 * order violation to enfore a general lock order of 1286 * sleepable locks before non-sleepable locks. 1287 */ 1288 if (((lock->lo_flags & LO_SLEEPABLE) != 0 && 1289 (lock1->li_lock->lo_flags & LO_SLEEPABLE) == 0)) 1290 goto reversal; 1291 1292 /* 1293 * If we are locking Giant and this is a non-sleepable 1294 * lock, then treat it as a reversal. 1295 */ 1296 if ((lock1->li_lock->lo_flags & LO_SLEEPABLE) == 0 && 1297 lock == &Giant.lock_object) 1298 goto reversal; 1299 1300 /* 1301 * Check the lock order hierarchy for a reveresal. 1302 */ 1303 if (!isitmydescendant(w, w1)) 1304 continue; 1305 reversal: 1306 1307 /* 1308 * We have a lock order violation, check to see if it 1309 * is allowed or has already been yelled about. 1310 */ 1311 #ifdef BLESSING 1312 1313 /* 1314 * If the lock order is blessed, just bail. We don't 1315 * look for other lock order violations though, which 1316 * may be a bug. 1317 */ 1318 if (blessed(w, w1)) 1319 goto out; 1320 #endif 1321 1322 /* Bail if this violation is known */ 1323 if (w_rmatrix[w1->w_index][w->w_index] & WITNESS_REVERSAL) 1324 goto out; 1325 1326 /* Record this as a violation */ 1327 w_rmatrix[w1->w_index][w->w_index] |= WITNESS_REVERSAL; 1328 w_rmatrix[w->w_index][w1->w_index] |= WITNESS_REVERSAL; 1329 w->w_reversed = w1->w_reversed = 1; 1330 witness_increment_graph_generation(); 1331 mtx_unlock_spin(&w_mtx); 1332 1333 #ifdef WITNESS_NO_VNODE 1334 /* 1335 * There are known LORs between VNODE locks. They are 1336 * not an indication of a bug. VNODE locks are flagged 1337 * as such (LO_IS_VNODE) and we don't yell if the LOR 1338 * is between 2 VNODE locks. 1339 */ 1340 if ((lock->lo_flags & LO_IS_VNODE) != 0 && 1341 (lock1->li_lock->lo_flags & LO_IS_VNODE) != 0) 1342 return; 1343 #endif 1344 1345 /* 1346 * Ok, yell about it. 1347 */ 1348 if (((lock->lo_flags & LO_SLEEPABLE) != 0 && 1349 (lock1->li_lock->lo_flags & LO_SLEEPABLE) == 0)) 1350 witness_output( 1351 "lock order reversal: (sleepable after non-sleepable)\n"); 1352 else if ((lock1->li_lock->lo_flags & LO_SLEEPABLE) == 0 1353 && lock == &Giant.lock_object) 1354 witness_output( 1355 "lock order reversal: (Giant after non-sleepable)\n"); 1356 else 1357 witness_output("lock order reversal:\n"); 1358 1359 /* 1360 * Try to locate an earlier lock with 1361 * witness w in our list. 1362 */ 1363 do { 1364 lock2 = &lle->ll_children[i]; 1365 MPASS(lock2->li_lock != NULL); 1366 if (lock2->li_lock->lo_witness == w) 1367 break; 1368 if (i == 0 && lle->ll_next != NULL) { 1369 lle = lle->ll_next; 1370 i = lle->ll_count - 1; 1371 MPASS(i >= 0 && i < LOCK_NCHILDREN); 1372 } else 1373 i--; 1374 } while (i >= 0); 1375 if (i < 0) { 1376 witness_output(" 1st %p %s (%s) @ %s:%d\n", 1377 lock1->li_lock, lock1->li_lock->lo_name, 1378 w1->w_name, fixup_filename(lock1->li_file), 1379 lock1->li_line); 1380 witness_output(" 2nd %p %s (%s) @ %s:%d\n", lock, 1381 lock->lo_name, w->w_name, 1382 fixup_filename(file), line); 1383 } else { 1384 witness_output(" 1st %p %s (%s) @ %s:%d\n", 1385 lock2->li_lock, lock2->li_lock->lo_name, 1386 lock2->li_lock->lo_witness->w_name, 1387 fixup_filename(lock2->li_file), 1388 lock2->li_line); 1389 witness_output(" 2nd %p %s (%s) @ %s:%d\n", 1390 lock1->li_lock, lock1->li_lock->lo_name, 1391 w1->w_name, fixup_filename(lock1->li_file), 1392 lock1->li_line); 1393 witness_output(" 3rd %p %s (%s) @ %s:%d\n", lock, 1394 lock->lo_name, w->w_name, 1395 fixup_filename(file), line); 1396 } 1397 witness_debugger(1, __func__); 1398 return; 1399 } 1400 } 1401 1402 /* 1403 * If requested, build a new lock order. However, don't build a new 1404 * relationship between a sleepable lock and Giant if it is in the 1405 * wrong direction. The correct lock order is that sleepable locks 1406 * always come before Giant. 1407 */ 1408 if (flags & LOP_NEWORDER && 1409 !(plock->li_lock == &Giant.lock_object && 1410 (lock->lo_flags & LO_SLEEPABLE) != 0)) { 1411 CTR3(KTR_WITNESS, "%s: adding %s as a child of %s", __func__, 1412 w->w_name, plock->li_lock->lo_witness->w_name); 1413 itismychild(plock->li_lock->lo_witness, w); 1414 } 1415 out: 1416 mtx_unlock_spin(&w_mtx); 1417 } 1418 1419 void 1420 witness_lock(struct lock_object *lock, int flags, const char *file, int line) 1421 { 1422 struct lock_list_entry **lock_list, *lle; 1423 struct lock_instance *instance; 1424 struct witness *w; 1425 struct thread *td; 1426 1427 if (witness_cold || witness_watch == -1 || lock->lo_witness == NULL || 1428 panicstr != NULL) 1429 return; 1430 w = lock->lo_witness; 1431 td = curthread; 1432 1433 /* Determine lock list for this lock. */ 1434 if (LOCK_CLASS(lock)->lc_flags & LC_SLEEPLOCK) 1435 lock_list = &td->td_sleeplocks; 1436 else 1437 lock_list = PCPU_PTR(spinlocks); 1438 1439 /* Check to see if we are recursing on a lock we already own. */ 1440 instance = find_instance(*lock_list, lock); 1441 if (instance != NULL) { 1442 instance->li_flags++; 1443 CTR4(KTR_WITNESS, "%s: pid %d recursed on %s r=%d", __func__, 1444 td->td_proc->p_pid, lock->lo_name, 1445 instance->li_flags & LI_RECURSEMASK); 1446 instance->li_file = file; 1447 instance->li_line = line; 1448 return; 1449 } 1450 1451 /* Update per-witness last file and line acquire. */ 1452 w->w_file = file; 1453 w->w_line = line; 1454 1455 /* Find the next open lock instance in the list and fill it. */ 1456 lle = *lock_list; 1457 if (lle == NULL || lle->ll_count == LOCK_NCHILDREN) { 1458 lle = witness_lock_list_get(); 1459 if (lle == NULL) 1460 return; 1461 lle->ll_next = *lock_list; 1462 CTR3(KTR_WITNESS, "%s: pid %d added lle %p", __func__, 1463 td->td_proc->p_pid, lle); 1464 *lock_list = lle; 1465 } 1466 instance = &lle->ll_children[lle->ll_count++]; 1467 instance->li_lock = lock; 1468 instance->li_line = line; 1469 instance->li_file = file; 1470 if ((flags & LOP_EXCLUSIVE) != 0) 1471 instance->li_flags = LI_EXCLUSIVE; 1472 else 1473 instance->li_flags = 0; 1474 CTR4(KTR_WITNESS, "%s: pid %d added %s as lle[%d]", __func__, 1475 td->td_proc->p_pid, lock->lo_name, lle->ll_count - 1); 1476 } 1477 1478 void 1479 witness_upgrade(struct lock_object *lock, int flags, const char *file, int line) 1480 { 1481 struct lock_instance *instance; 1482 struct lock_class *class; 1483 1484 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); 1485 if (lock->lo_witness == NULL || witness_watch == -1 || panicstr != NULL) 1486 return; 1487 class = LOCK_CLASS(lock); 1488 if (witness_watch) { 1489 if ((lock->lo_flags & LO_UPGRADABLE) == 0) 1490 kassert_panic( 1491 "upgrade of non-upgradable lock (%s) %s @ %s:%d", 1492 class->lc_name, lock->lo_name, 1493 fixup_filename(file), line); 1494 if ((class->lc_flags & LC_SLEEPLOCK) == 0) 1495 kassert_panic( 1496 "upgrade of non-sleep lock (%s) %s @ %s:%d", 1497 class->lc_name, lock->lo_name, 1498 fixup_filename(file), line); 1499 } 1500 instance = find_instance(curthread->td_sleeplocks, lock); 1501 if (instance == NULL) { 1502 kassert_panic("upgrade of unlocked lock (%s) %s @ %s:%d", 1503 class->lc_name, lock->lo_name, 1504 fixup_filename(file), line); 1505 return; 1506 } 1507 if (witness_watch) { 1508 if ((instance->li_flags & LI_EXCLUSIVE) != 0) 1509 kassert_panic( 1510 "upgrade of exclusive lock (%s) %s @ %s:%d", 1511 class->lc_name, lock->lo_name, 1512 fixup_filename(file), line); 1513 if ((instance->li_flags & LI_RECURSEMASK) != 0) 1514 kassert_panic( 1515 "upgrade of recursed lock (%s) %s r=%d @ %s:%d", 1516 class->lc_name, lock->lo_name, 1517 instance->li_flags & LI_RECURSEMASK, 1518 fixup_filename(file), line); 1519 } 1520 instance->li_flags |= LI_EXCLUSIVE; 1521 } 1522 1523 void 1524 witness_downgrade(struct lock_object *lock, int flags, const char *file, 1525 int line) 1526 { 1527 struct lock_instance *instance; 1528 struct lock_class *class; 1529 1530 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); 1531 if (lock->lo_witness == NULL || witness_watch == -1 || panicstr != NULL) 1532 return; 1533 class = LOCK_CLASS(lock); 1534 if (witness_watch) { 1535 if ((lock->lo_flags & LO_UPGRADABLE) == 0) 1536 kassert_panic( 1537 "downgrade of non-upgradable lock (%s) %s @ %s:%d", 1538 class->lc_name, lock->lo_name, 1539 fixup_filename(file), line); 1540 if ((class->lc_flags & LC_SLEEPLOCK) == 0) 1541 kassert_panic( 1542 "downgrade of non-sleep lock (%s) %s @ %s:%d", 1543 class->lc_name, lock->lo_name, 1544 fixup_filename(file), line); 1545 } 1546 instance = find_instance(curthread->td_sleeplocks, lock); 1547 if (instance == NULL) { 1548 kassert_panic("downgrade of unlocked lock (%s) %s @ %s:%d", 1549 class->lc_name, lock->lo_name, 1550 fixup_filename(file), line); 1551 return; 1552 } 1553 if (witness_watch) { 1554 if ((instance->li_flags & LI_EXCLUSIVE) == 0) 1555 kassert_panic( 1556 "downgrade of shared lock (%s) %s @ %s:%d", 1557 class->lc_name, lock->lo_name, 1558 fixup_filename(file), line); 1559 if ((instance->li_flags & LI_RECURSEMASK) != 0) 1560 kassert_panic( 1561 "downgrade of recursed lock (%s) %s r=%d @ %s:%d", 1562 class->lc_name, lock->lo_name, 1563 instance->li_flags & LI_RECURSEMASK, 1564 fixup_filename(file), line); 1565 } 1566 instance->li_flags &= ~LI_EXCLUSIVE; 1567 } 1568 1569 void 1570 witness_unlock(struct lock_object *lock, int flags, const char *file, int line) 1571 { 1572 struct lock_list_entry **lock_list, *lle; 1573 struct lock_instance *instance; 1574 struct lock_class *class; 1575 struct thread *td; 1576 register_t s; 1577 int i, j; 1578 1579 if (witness_cold || lock->lo_witness == NULL || panicstr != NULL) 1580 return; 1581 td = curthread; 1582 class = LOCK_CLASS(lock); 1583 1584 /* Find lock instance associated with this lock. */ 1585 if (class->lc_flags & LC_SLEEPLOCK) 1586 lock_list = &td->td_sleeplocks; 1587 else 1588 lock_list = PCPU_PTR(spinlocks); 1589 lle = *lock_list; 1590 for (; *lock_list != NULL; lock_list = &(*lock_list)->ll_next) 1591 for (i = 0; i < (*lock_list)->ll_count; i++) { 1592 instance = &(*lock_list)->ll_children[i]; 1593 if (instance->li_lock == lock) 1594 goto found; 1595 } 1596 1597 /* 1598 * When disabling WITNESS through witness_watch we could end up in 1599 * having registered locks in the td_sleeplocks queue. 1600 * We have to make sure we flush these queues, so just search for 1601 * eventual register locks and remove them. 1602 */ 1603 if (witness_watch > 0) { 1604 kassert_panic("lock (%s) %s not locked @ %s:%d", class->lc_name, 1605 lock->lo_name, fixup_filename(file), line); 1606 return; 1607 } else { 1608 return; 1609 } 1610 found: 1611 1612 /* First, check for shared/exclusive mismatches. */ 1613 if ((instance->li_flags & LI_EXCLUSIVE) != 0 && witness_watch > 0 && 1614 (flags & LOP_EXCLUSIVE) == 0) { 1615 witness_output("shared unlock of (%s) %s @ %s:%d\n", 1616 class->lc_name, lock->lo_name, fixup_filename(file), line); 1617 witness_output("while exclusively locked from %s:%d\n", 1618 fixup_filename(instance->li_file), instance->li_line); 1619 kassert_panic("excl->ushare"); 1620 } 1621 if ((instance->li_flags & LI_EXCLUSIVE) == 0 && witness_watch > 0 && 1622 (flags & LOP_EXCLUSIVE) != 0) { 1623 witness_output("exclusive unlock of (%s) %s @ %s:%d\n", 1624 class->lc_name, lock->lo_name, fixup_filename(file), line); 1625 witness_output("while share locked from %s:%d\n", 1626 fixup_filename(instance->li_file), 1627 instance->li_line); 1628 kassert_panic("share->uexcl"); 1629 } 1630 /* If we are recursed, unrecurse. */ 1631 if ((instance->li_flags & LI_RECURSEMASK) > 0) { 1632 CTR4(KTR_WITNESS, "%s: pid %d unrecursed on %s r=%d", __func__, 1633 td->td_proc->p_pid, instance->li_lock->lo_name, 1634 instance->li_flags); 1635 instance->li_flags--; 1636 return; 1637 } 1638 /* The lock is now being dropped, check for NORELEASE flag */ 1639 if ((instance->li_flags & LI_NORELEASE) != 0 && witness_watch > 0) { 1640 witness_output("forbidden unlock of (%s) %s @ %s:%d\n", 1641 class->lc_name, lock->lo_name, fixup_filename(file), line); 1642 kassert_panic("lock marked norelease"); 1643 } 1644 1645 /* Otherwise, remove this item from the list. */ 1646 s = intr_disable(); 1647 CTR4(KTR_WITNESS, "%s: pid %d removed %s from lle[%d]", __func__, 1648 td->td_proc->p_pid, instance->li_lock->lo_name, 1649 (*lock_list)->ll_count - 1); 1650 for (j = i; j < (*lock_list)->ll_count - 1; j++) 1651 (*lock_list)->ll_children[j] = 1652 (*lock_list)->ll_children[j + 1]; 1653 (*lock_list)->ll_count--; 1654 intr_restore(s); 1655 1656 /* 1657 * In order to reduce contention on w_mtx, we want to keep always an 1658 * head object into lists so that frequent allocation from the 1659 * free witness pool (and subsequent locking) is avoided. 1660 * In order to maintain the current code simple, when the head 1661 * object is totally unloaded it means also that we do not have 1662 * further objects in the list, so the list ownership needs to be 1663 * hand over to another object if the current head needs to be freed. 1664 */ 1665 if ((*lock_list)->ll_count == 0) { 1666 if (*lock_list == lle) { 1667 if (lle->ll_next == NULL) 1668 return; 1669 } else 1670 lle = *lock_list; 1671 *lock_list = lle->ll_next; 1672 CTR3(KTR_WITNESS, "%s: pid %d removed lle %p", __func__, 1673 td->td_proc->p_pid, lle); 1674 witness_lock_list_free(lle); 1675 } 1676 } 1677 1678 void 1679 witness_thread_exit(struct thread *td) 1680 { 1681 struct lock_list_entry *lle; 1682 int i, n; 1683 1684 lle = td->td_sleeplocks; 1685 if (lle == NULL || panicstr != NULL) 1686 return; 1687 if (lle->ll_count != 0) { 1688 for (n = 0; lle != NULL; lle = lle->ll_next) 1689 for (i = lle->ll_count - 1; i >= 0; i--) { 1690 if (n == 0) 1691 witness_output( 1692 "Thread %p exiting with the following locks held:\n", td); 1693 n++; 1694 witness_list_lock(&lle->ll_children[i], 1695 witness_output); 1696 1697 } 1698 kassert_panic( 1699 "Thread %p cannot exit while holding sleeplocks\n", td); 1700 } 1701 witness_lock_list_free(lle); 1702 } 1703 1704 /* 1705 * Warn if any locks other than 'lock' are held. Flags can be passed in to 1706 * exempt Giant and sleepable locks from the checks as well. If any 1707 * non-exempt locks are held, then a supplied message is printed to the 1708 * output channel along with a list of the offending locks. If indicated in the 1709 * flags then a failure results in a panic as well. 1710 */ 1711 int 1712 witness_warn(int flags, struct lock_object *lock, const char *fmt, ...) 1713 { 1714 struct lock_list_entry *lock_list, *lle; 1715 struct lock_instance *lock1; 1716 struct thread *td; 1717 va_list ap; 1718 int i, n; 1719 1720 if (witness_cold || witness_watch < 1 || panicstr != NULL) 1721 return (0); 1722 n = 0; 1723 td = curthread; 1724 for (lle = td->td_sleeplocks; lle != NULL; lle = lle->ll_next) 1725 for (i = lle->ll_count - 1; i >= 0; i--) { 1726 lock1 = &lle->ll_children[i]; 1727 if (lock1->li_lock == lock) 1728 continue; 1729 if (flags & WARN_GIANTOK && 1730 lock1->li_lock == &Giant.lock_object) 1731 continue; 1732 if (flags & WARN_SLEEPOK && 1733 (lock1->li_lock->lo_flags & LO_SLEEPABLE) != 0) 1734 continue; 1735 if (n == 0) { 1736 va_start(ap, fmt); 1737 vprintf(fmt, ap); 1738 va_end(ap); 1739 printf(" with the following %slocks held:\n", 1740 (flags & WARN_SLEEPOK) != 0 ? 1741 "non-sleepable " : ""); 1742 } 1743 n++; 1744 witness_list_lock(lock1, printf); 1745 } 1746 1747 /* 1748 * Pin the thread in order to avoid problems with thread migration. 1749 * Once that all verifies are passed about spinlocks ownership, 1750 * the thread is in a safe path and it can be unpinned. 1751 */ 1752 sched_pin(); 1753 lock_list = PCPU_GET(spinlocks); 1754 if (lock_list != NULL && lock_list->ll_count != 0) { 1755 sched_unpin(); 1756 1757 /* 1758 * We should only have one spinlock and as long as 1759 * the flags cannot match for this locks class, 1760 * check if the first spinlock is the one curthread 1761 * should hold. 1762 */ 1763 lock1 = &lock_list->ll_children[lock_list->ll_count - 1]; 1764 if (lock_list->ll_count == 1 && lock_list->ll_next == NULL && 1765 lock1->li_lock == lock && n == 0) 1766 return (0); 1767 1768 va_start(ap, fmt); 1769 vprintf(fmt, ap); 1770 va_end(ap); 1771 printf(" with the following %slocks held:\n", 1772 (flags & WARN_SLEEPOK) != 0 ? "non-sleepable " : ""); 1773 n += witness_list_locks(&lock_list, printf); 1774 } else 1775 sched_unpin(); 1776 if (flags & WARN_PANIC && n) 1777 kassert_panic("%s", __func__); 1778 else 1779 witness_debugger(n, __func__); 1780 return (n); 1781 } 1782 1783 const char * 1784 witness_file(struct lock_object *lock) 1785 { 1786 struct witness *w; 1787 1788 if (witness_cold || witness_watch < 1 || lock->lo_witness == NULL) 1789 return ("?"); 1790 w = lock->lo_witness; 1791 return (w->w_file); 1792 } 1793 1794 int 1795 witness_line(struct lock_object *lock) 1796 { 1797 struct witness *w; 1798 1799 if (witness_cold || witness_watch < 1 || lock->lo_witness == NULL) 1800 return (0); 1801 w = lock->lo_witness; 1802 return (w->w_line); 1803 } 1804 1805 static struct witness * 1806 enroll(const char *description, struct lock_class *lock_class) 1807 { 1808 struct witness *w; 1809 struct witness_list *typelist; 1810 1811 MPASS(description != NULL); 1812 1813 if (witness_watch == -1 || panicstr != NULL) 1814 return (NULL); 1815 if ((lock_class->lc_flags & LC_SPINLOCK)) { 1816 if (witness_skipspin) 1817 return (NULL); 1818 else 1819 typelist = &w_spin; 1820 } else if ((lock_class->lc_flags & LC_SLEEPLOCK)) { 1821 typelist = &w_sleep; 1822 } else { 1823 kassert_panic("lock class %s is not sleep or spin", 1824 lock_class->lc_name); 1825 return (NULL); 1826 } 1827 1828 mtx_lock_spin(&w_mtx); 1829 w = witness_hash_get(description); 1830 if (w) 1831 goto found; 1832 if ((w = witness_get()) == NULL) 1833 return (NULL); 1834 MPASS(strlen(description) < MAX_W_NAME); 1835 strcpy(w->w_name, description); 1836 w->w_class = lock_class; 1837 w->w_refcount = 1; 1838 STAILQ_INSERT_HEAD(&w_all, w, w_list); 1839 if (lock_class->lc_flags & LC_SPINLOCK) { 1840 STAILQ_INSERT_HEAD(&w_spin, w, w_typelist); 1841 w_spin_cnt++; 1842 } else if (lock_class->lc_flags & LC_SLEEPLOCK) { 1843 STAILQ_INSERT_HEAD(&w_sleep, w, w_typelist); 1844 w_sleep_cnt++; 1845 } 1846 1847 /* Insert new witness into the hash */ 1848 witness_hash_put(w); 1849 witness_increment_graph_generation(); 1850 mtx_unlock_spin(&w_mtx); 1851 return (w); 1852 found: 1853 w->w_refcount++; 1854 if (w->w_refcount == 1) 1855 w->w_class = lock_class; 1856 mtx_unlock_spin(&w_mtx); 1857 if (lock_class != w->w_class) 1858 kassert_panic( 1859 "lock (%s) %s does not match earlier (%s) lock", 1860 description, lock_class->lc_name, 1861 w->w_class->lc_name); 1862 return (w); 1863 } 1864 1865 static void 1866 depart(struct witness *w) 1867 { 1868 struct witness_list *list; 1869 1870 MPASS(w->w_refcount == 0); 1871 if (w->w_class->lc_flags & LC_SLEEPLOCK) { 1872 list = &w_sleep; 1873 w_sleep_cnt--; 1874 } else { 1875 list = &w_spin; 1876 w_spin_cnt--; 1877 } 1878 /* 1879 * Set file to NULL as it may point into a loadable module. 1880 */ 1881 w->w_file = NULL; 1882 w->w_line = 0; 1883 witness_increment_graph_generation(); 1884 } 1885 1886 1887 static void 1888 adopt(struct witness *parent, struct witness *child) 1889 { 1890 int pi, ci, i, j; 1891 1892 if (witness_cold == 0) 1893 mtx_assert(&w_mtx, MA_OWNED); 1894 1895 /* If the relationship is already known, there's no work to be done. */ 1896 if (isitmychild(parent, child)) 1897 return; 1898 1899 /* When the structure of the graph changes, bump up the generation. */ 1900 witness_increment_graph_generation(); 1901 1902 /* 1903 * The hard part ... create the direct relationship, then propagate all 1904 * indirect relationships. 1905 */ 1906 pi = parent->w_index; 1907 ci = child->w_index; 1908 WITNESS_INDEX_ASSERT(pi); 1909 WITNESS_INDEX_ASSERT(ci); 1910 MPASS(pi != ci); 1911 w_rmatrix[pi][ci] |= WITNESS_PARENT; 1912 w_rmatrix[ci][pi] |= WITNESS_CHILD; 1913 1914 /* 1915 * If parent was not already an ancestor of child, 1916 * then we increment the descendant and ancestor counters. 1917 */ 1918 if ((w_rmatrix[pi][ci] & WITNESS_ANCESTOR) == 0) { 1919 parent->w_num_descendants++; 1920 child->w_num_ancestors++; 1921 } 1922 1923 /* 1924 * Find each ancestor of 'pi'. Note that 'pi' itself is counted as 1925 * an ancestor of 'pi' during this loop. 1926 */ 1927 for (i = 1; i <= w_max_used_index; i++) { 1928 if ((w_rmatrix[i][pi] & WITNESS_ANCESTOR_MASK) == 0 && 1929 (i != pi)) 1930 continue; 1931 1932 /* Find each descendant of 'i' and mark it as a descendant. */ 1933 for (j = 1; j <= w_max_used_index; j++) { 1934 1935 /* 1936 * Skip children that are already marked as 1937 * descendants of 'i'. 1938 */ 1939 if (w_rmatrix[i][j] & WITNESS_ANCESTOR_MASK) 1940 continue; 1941 1942 /* 1943 * We are only interested in descendants of 'ci'. Note 1944 * that 'ci' itself is counted as a descendant of 'ci'. 1945 */ 1946 if ((w_rmatrix[ci][j] & WITNESS_ANCESTOR_MASK) == 0 && 1947 (j != ci)) 1948 continue; 1949 w_rmatrix[i][j] |= WITNESS_ANCESTOR; 1950 w_rmatrix[j][i] |= WITNESS_DESCENDANT; 1951 w_data[i].w_num_descendants++; 1952 w_data[j].w_num_ancestors++; 1953 1954 /* 1955 * Make sure we aren't marking a node as both an 1956 * ancestor and descendant. We should have caught 1957 * this as a lock order reversal earlier. 1958 */ 1959 if ((w_rmatrix[i][j] & WITNESS_ANCESTOR_MASK) && 1960 (w_rmatrix[i][j] & WITNESS_DESCENDANT_MASK)) { 1961 printf("witness rmatrix paradox! [%d][%d]=%d " 1962 "both ancestor and descendant\n", 1963 i, j, w_rmatrix[i][j]); 1964 kdb_backtrace(); 1965 printf("Witness disabled.\n"); 1966 witness_watch = -1; 1967 } 1968 if ((w_rmatrix[j][i] & WITNESS_ANCESTOR_MASK) && 1969 (w_rmatrix[j][i] & WITNESS_DESCENDANT_MASK)) { 1970 printf("witness rmatrix paradox! [%d][%d]=%d " 1971 "both ancestor and descendant\n", 1972 j, i, w_rmatrix[j][i]); 1973 kdb_backtrace(); 1974 printf("Witness disabled.\n"); 1975 witness_watch = -1; 1976 } 1977 } 1978 } 1979 } 1980 1981 static void 1982 itismychild(struct witness *parent, struct witness *child) 1983 { 1984 int unlocked; 1985 1986 MPASS(child != NULL && parent != NULL); 1987 if (witness_cold == 0) 1988 mtx_assert(&w_mtx, MA_OWNED); 1989 1990 if (!witness_lock_type_equal(parent, child)) { 1991 if (witness_cold == 0) { 1992 unlocked = 1; 1993 mtx_unlock_spin(&w_mtx); 1994 } else { 1995 unlocked = 0; 1996 } 1997 kassert_panic( 1998 "%s: parent \"%s\" (%s) and child \"%s\" (%s) are not " 1999 "the same lock type", __func__, parent->w_name, 2000 parent->w_class->lc_name, child->w_name, 2001 child->w_class->lc_name); 2002 if (unlocked) 2003 mtx_lock_spin(&w_mtx); 2004 } 2005 adopt(parent, child); 2006 } 2007 2008 /* 2009 * Generic code for the isitmy*() functions. The rmask parameter is the 2010 * expected relationship of w1 to w2. 2011 */ 2012 static int 2013 _isitmyx(struct witness *w1, struct witness *w2, int rmask, const char *fname) 2014 { 2015 unsigned char r1, r2; 2016 int i1, i2; 2017 2018 i1 = w1->w_index; 2019 i2 = w2->w_index; 2020 WITNESS_INDEX_ASSERT(i1); 2021 WITNESS_INDEX_ASSERT(i2); 2022 r1 = w_rmatrix[i1][i2] & WITNESS_RELATED_MASK; 2023 r2 = w_rmatrix[i2][i1] & WITNESS_RELATED_MASK; 2024 2025 /* The flags on one better be the inverse of the flags on the other */ 2026 if (!((WITNESS_ATOD(r1) == r2 && WITNESS_DTOA(r2) == r1) || 2027 (WITNESS_DTOA(r1) == r2 && WITNESS_ATOD(r2) == r1))) { 2028 /* Don't squawk if we're potentially racing with an update. */ 2029 if (!mtx_owned(&w_mtx)) 2030 return (0); 2031 printf("%s: rmatrix mismatch between %s (index %d) and %s " 2032 "(index %d): w_rmatrix[%d][%d] == %hhx but " 2033 "w_rmatrix[%d][%d] == %hhx\n", 2034 fname, w1->w_name, i1, w2->w_name, i2, i1, i2, r1, 2035 i2, i1, r2); 2036 kdb_backtrace(); 2037 printf("Witness disabled.\n"); 2038 witness_watch = -1; 2039 } 2040 return (r1 & rmask); 2041 } 2042 2043 /* 2044 * Checks if @child is a direct child of @parent. 2045 */ 2046 static int 2047 isitmychild(struct witness *parent, struct witness *child) 2048 { 2049 2050 return (_isitmyx(parent, child, WITNESS_PARENT, __func__)); 2051 } 2052 2053 /* 2054 * Checks if @descendant is a direct or inderect descendant of @ancestor. 2055 */ 2056 static int 2057 isitmydescendant(struct witness *ancestor, struct witness *descendant) 2058 { 2059 2060 return (_isitmyx(ancestor, descendant, WITNESS_ANCESTOR_MASK, 2061 __func__)); 2062 } 2063 2064 #ifdef BLESSING 2065 static int 2066 blessed(struct witness *w1, struct witness *w2) 2067 { 2068 int i; 2069 struct witness_blessed *b; 2070 2071 for (i = 0; i < nitems(blessed_list); i++) { 2072 b = &blessed_list[i]; 2073 if (strcmp(w1->w_name, b->b_lock1) == 0) { 2074 if (strcmp(w2->w_name, b->b_lock2) == 0) 2075 return (1); 2076 continue; 2077 } 2078 if (strcmp(w1->w_name, b->b_lock2) == 0) 2079 if (strcmp(w2->w_name, b->b_lock1) == 0) 2080 return (1); 2081 } 2082 return (0); 2083 } 2084 #endif 2085 2086 static struct witness * 2087 witness_get(void) 2088 { 2089 struct witness *w; 2090 int index; 2091 2092 if (witness_cold == 0) 2093 mtx_assert(&w_mtx, MA_OWNED); 2094 2095 if (witness_watch == -1) { 2096 mtx_unlock_spin(&w_mtx); 2097 return (NULL); 2098 } 2099 if (STAILQ_EMPTY(&w_free)) { 2100 witness_watch = -1; 2101 mtx_unlock_spin(&w_mtx); 2102 printf("WITNESS: unable to allocate a new witness object\n"); 2103 return (NULL); 2104 } 2105 w = STAILQ_FIRST(&w_free); 2106 STAILQ_REMOVE_HEAD(&w_free, w_list); 2107 w_free_cnt--; 2108 index = w->w_index; 2109 MPASS(index > 0 && index == w_max_used_index+1 && 2110 index < witness_count); 2111 bzero(w, sizeof(*w)); 2112 w->w_index = index; 2113 if (index > w_max_used_index) 2114 w_max_used_index = index; 2115 return (w); 2116 } 2117 2118 static void 2119 witness_free(struct witness *w) 2120 { 2121 2122 STAILQ_INSERT_HEAD(&w_free, w, w_list); 2123 w_free_cnt++; 2124 } 2125 2126 static struct lock_list_entry * 2127 witness_lock_list_get(void) 2128 { 2129 struct lock_list_entry *lle; 2130 2131 if (witness_watch == -1) 2132 return (NULL); 2133 mtx_lock_spin(&w_mtx); 2134 lle = w_lock_list_free; 2135 if (lle == NULL) { 2136 witness_watch = -1; 2137 mtx_unlock_spin(&w_mtx); 2138 printf("%s: witness exhausted\n", __func__); 2139 return (NULL); 2140 } 2141 w_lock_list_free = lle->ll_next; 2142 mtx_unlock_spin(&w_mtx); 2143 bzero(lle, sizeof(*lle)); 2144 return (lle); 2145 } 2146 2147 static void 2148 witness_lock_list_free(struct lock_list_entry *lle) 2149 { 2150 2151 mtx_lock_spin(&w_mtx); 2152 lle->ll_next = w_lock_list_free; 2153 w_lock_list_free = lle; 2154 mtx_unlock_spin(&w_mtx); 2155 } 2156 2157 static struct lock_instance * 2158 find_instance(struct lock_list_entry *list, const struct lock_object *lock) 2159 { 2160 struct lock_list_entry *lle; 2161 struct lock_instance *instance; 2162 int i; 2163 2164 for (lle = list; lle != NULL; lle = lle->ll_next) 2165 for (i = lle->ll_count - 1; i >= 0; i--) { 2166 instance = &lle->ll_children[i]; 2167 if (instance->li_lock == lock) 2168 return (instance); 2169 } 2170 return (NULL); 2171 } 2172 2173 static void 2174 witness_list_lock(struct lock_instance *instance, 2175 int (*prnt)(const char *fmt, ...)) 2176 { 2177 struct lock_object *lock; 2178 2179 lock = instance->li_lock; 2180 prnt("%s %s %s", (instance->li_flags & LI_EXCLUSIVE) != 0 ? 2181 "exclusive" : "shared", LOCK_CLASS(lock)->lc_name, lock->lo_name); 2182 if (lock->lo_witness->w_name != lock->lo_name) 2183 prnt(" (%s)", lock->lo_witness->w_name); 2184 prnt(" r = %d (%p) locked @ %s:%d\n", 2185 instance->li_flags & LI_RECURSEMASK, lock, 2186 fixup_filename(instance->li_file), instance->li_line); 2187 } 2188 2189 static int 2190 witness_output(const char *fmt, ...) 2191 { 2192 va_list ap; 2193 int ret; 2194 2195 va_start(ap, fmt); 2196 ret = witness_voutput(fmt, ap); 2197 va_end(ap); 2198 return (ret); 2199 } 2200 2201 static int 2202 witness_voutput(const char *fmt, va_list ap) 2203 { 2204 int ret; 2205 2206 ret = 0; 2207 switch (witness_channel) { 2208 case WITNESS_CONSOLE: 2209 ret = vprintf(fmt, ap); 2210 break; 2211 case WITNESS_LOG: 2212 vlog(LOG_NOTICE, fmt, ap); 2213 break; 2214 case WITNESS_NONE: 2215 break; 2216 } 2217 return (ret); 2218 } 2219 2220 #ifdef DDB 2221 static int 2222 witness_thread_has_locks(struct thread *td) 2223 { 2224 2225 if (td->td_sleeplocks == NULL) 2226 return (0); 2227 return (td->td_sleeplocks->ll_count != 0); 2228 } 2229 2230 static int 2231 witness_proc_has_locks(struct proc *p) 2232 { 2233 struct thread *td; 2234 2235 FOREACH_THREAD_IN_PROC(p, td) { 2236 if (witness_thread_has_locks(td)) 2237 return (1); 2238 } 2239 return (0); 2240 } 2241 #endif 2242 2243 int 2244 witness_list_locks(struct lock_list_entry **lock_list, 2245 int (*prnt)(const char *fmt, ...)) 2246 { 2247 struct lock_list_entry *lle; 2248 int i, nheld; 2249 2250 nheld = 0; 2251 for (lle = *lock_list; lle != NULL; lle = lle->ll_next) 2252 for (i = lle->ll_count - 1; i >= 0; i--) { 2253 witness_list_lock(&lle->ll_children[i], prnt); 2254 nheld++; 2255 } 2256 return (nheld); 2257 } 2258 2259 /* 2260 * This is a bit risky at best. We call this function when we have timed 2261 * out acquiring a spin lock, and we assume that the other CPU is stuck 2262 * with this lock held. So, we go groveling around in the other CPU's 2263 * per-cpu data to try to find the lock instance for this spin lock to 2264 * see when it was last acquired. 2265 */ 2266 void 2267 witness_display_spinlock(struct lock_object *lock, struct thread *owner, 2268 int (*prnt)(const char *fmt, ...)) 2269 { 2270 struct lock_instance *instance; 2271 struct pcpu *pc; 2272 2273 if (owner->td_critnest == 0 || owner->td_oncpu == NOCPU) 2274 return; 2275 pc = pcpu_find(owner->td_oncpu); 2276 instance = find_instance(pc->pc_spinlocks, lock); 2277 if (instance != NULL) 2278 witness_list_lock(instance, prnt); 2279 } 2280 2281 void 2282 witness_save(struct lock_object *lock, const char **filep, int *linep) 2283 { 2284 struct lock_list_entry *lock_list; 2285 struct lock_instance *instance; 2286 struct lock_class *class; 2287 2288 /* 2289 * This function is used independently in locking code to deal with 2290 * Giant, SCHEDULER_STOPPED() check can be removed here after Giant 2291 * is gone. 2292 */ 2293 if (SCHEDULER_STOPPED()) 2294 return; 2295 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); 2296 if (lock->lo_witness == NULL || witness_watch == -1 || panicstr != NULL) 2297 return; 2298 class = LOCK_CLASS(lock); 2299 if (class->lc_flags & LC_SLEEPLOCK) 2300 lock_list = curthread->td_sleeplocks; 2301 else { 2302 if (witness_skipspin) 2303 return; 2304 lock_list = PCPU_GET(spinlocks); 2305 } 2306 instance = find_instance(lock_list, lock); 2307 if (instance == NULL) { 2308 kassert_panic("%s: lock (%s) %s not locked", __func__, 2309 class->lc_name, lock->lo_name); 2310 return; 2311 } 2312 *filep = instance->li_file; 2313 *linep = instance->li_line; 2314 } 2315 2316 void 2317 witness_restore(struct lock_object *lock, const char *file, int line) 2318 { 2319 struct lock_list_entry *lock_list; 2320 struct lock_instance *instance; 2321 struct lock_class *class; 2322 2323 /* 2324 * This function is used independently in locking code to deal with 2325 * Giant, SCHEDULER_STOPPED() check can be removed here after Giant 2326 * is gone. 2327 */ 2328 if (SCHEDULER_STOPPED()) 2329 return; 2330 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); 2331 if (lock->lo_witness == NULL || witness_watch == -1 || panicstr != NULL) 2332 return; 2333 class = LOCK_CLASS(lock); 2334 if (class->lc_flags & LC_SLEEPLOCK) 2335 lock_list = curthread->td_sleeplocks; 2336 else { 2337 if (witness_skipspin) 2338 return; 2339 lock_list = PCPU_GET(spinlocks); 2340 } 2341 instance = find_instance(lock_list, lock); 2342 if (instance == NULL) 2343 kassert_panic("%s: lock (%s) %s not locked", __func__, 2344 class->lc_name, lock->lo_name); 2345 lock->lo_witness->w_file = file; 2346 lock->lo_witness->w_line = line; 2347 if (instance == NULL) 2348 return; 2349 instance->li_file = file; 2350 instance->li_line = line; 2351 } 2352 2353 void 2354 witness_assert(const struct lock_object *lock, int flags, const char *file, 2355 int line) 2356 { 2357 #ifdef INVARIANT_SUPPORT 2358 struct lock_instance *instance; 2359 struct lock_class *class; 2360 2361 if (lock->lo_witness == NULL || witness_watch < 1 || panicstr != NULL) 2362 return; 2363 class = LOCK_CLASS(lock); 2364 if ((class->lc_flags & LC_SLEEPLOCK) != 0) 2365 instance = find_instance(curthread->td_sleeplocks, lock); 2366 else if ((class->lc_flags & LC_SPINLOCK) != 0) 2367 instance = find_instance(PCPU_GET(spinlocks), lock); 2368 else { 2369 kassert_panic("Lock (%s) %s is not sleep or spin!", 2370 class->lc_name, lock->lo_name); 2371 return; 2372 } 2373 switch (flags) { 2374 case LA_UNLOCKED: 2375 if (instance != NULL) 2376 kassert_panic("Lock (%s) %s locked @ %s:%d.", 2377 class->lc_name, lock->lo_name, 2378 fixup_filename(file), line); 2379 break; 2380 case LA_LOCKED: 2381 case LA_LOCKED | LA_RECURSED: 2382 case LA_LOCKED | LA_NOTRECURSED: 2383 case LA_SLOCKED: 2384 case LA_SLOCKED | LA_RECURSED: 2385 case LA_SLOCKED | LA_NOTRECURSED: 2386 case LA_XLOCKED: 2387 case LA_XLOCKED | LA_RECURSED: 2388 case LA_XLOCKED | LA_NOTRECURSED: 2389 if (instance == NULL) { 2390 kassert_panic("Lock (%s) %s not locked @ %s:%d.", 2391 class->lc_name, lock->lo_name, 2392 fixup_filename(file), line); 2393 break; 2394 } 2395 if ((flags & LA_XLOCKED) != 0 && 2396 (instance->li_flags & LI_EXCLUSIVE) == 0) 2397 kassert_panic( 2398 "Lock (%s) %s not exclusively locked @ %s:%d.", 2399 class->lc_name, lock->lo_name, 2400 fixup_filename(file), line); 2401 if ((flags & LA_SLOCKED) != 0 && 2402 (instance->li_flags & LI_EXCLUSIVE) != 0) 2403 kassert_panic( 2404 "Lock (%s) %s exclusively locked @ %s:%d.", 2405 class->lc_name, lock->lo_name, 2406 fixup_filename(file), line); 2407 if ((flags & LA_RECURSED) != 0 && 2408 (instance->li_flags & LI_RECURSEMASK) == 0) 2409 kassert_panic("Lock (%s) %s not recursed @ %s:%d.", 2410 class->lc_name, lock->lo_name, 2411 fixup_filename(file), line); 2412 if ((flags & LA_NOTRECURSED) != 0 && 2413 (instance->li_flags & LI_RECURSEMASK) != 0) 2414 kassert_panic("Lock (%s) %s recursed @ %s:%d.", 2415 class->lc_name, lock->lo_name, 2416 fixup_filename(file), line); 2417 break; 2418 default: 2419 kassert_panic("Invalid lock assertion at %s:%d.", 2420 fixup_filename(file), line); 2421 2422 } 2423 #endif /* INVARIANT_SUPPORT */ 2424 } 2425 2426 static void 2427 witness_setflag(struct lock_object *lock, int flag, int set) 2428 { 2429 struct lock_list_entry *lock_list; 2430 struct lock_instance *instance; 2431 struct lock_class *class; 2432 2433 if (lock->lo_witness == NULL || witness_watch == -1 || panicstr != NULL) 2434 return; 2435 class = LOCK_CLASS(lock); 2436 if (class->lc_flags & LC_SLEEPLOCK) 2437 lock_list = curthread->td_sleeplocks; 2438 else { 2439 if (witness_skipspin) 2440 return; 2441 lock_list = PCPU_GET(spinlocks); 2442 } 2443 instance = find_instance(lock_list, lock); 2444 if (instance == NULL) { 2445 kassert_panic("%s: lock (%s) %s not locked", __func__, 2446 class->lc_name, lock->lo_name); 2447 return; 2448 } 2449 2450 if (set) 2451 instance->li_flags |= flag; 2452 else 2453 instance->li_flags &= ~flag; 2454 } 2455 2456 void 2457 witness_norelease(struct lock_object *lock) 2458 { 2459 2460 witness_setflag(lock, LI_NORELEASE, 1); 2461 } 2462 2463 void 2464 witness_releaseok(struct lock_object *lock) 2465 { 2466 2467 witness_setflag(lock, LI_NORELEASE, 0); 2468 } 2469 2470 #ifdef DDB 2471 static void 2472 witness_ddb_list(struct thread *td) 2473 { 2474 2475 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); 2476 KASSERT(kdb_active, ("%s: not in the debugger", __func__)); 2477 2478 if (witness_watch < 1) 2479 return; 2480 2481 witness_list_locks(&td->td_sleeplocks, db_printf); 2482 2483 /* 2484 * We only handle spinlocks if td == curthread. This is somewhat broken 2485 * if td is currently executing on some other CPU and holds spin locks 2486 * as we won't display those locks. If we had a MI way of getting 2487 * the per-cpu data for a given cpu then we could use 2488 * td->td_oncpu to get the list of spinlocks for this thread 2489 * and "fix" this. 2490 * 2491 * That still wouldn't really fix this unless we locked the scheduler 2492 * lock or stopped the other CPU to make sure it wasn't changing the 2493 * list out from under us. It is probably best to just not try to 2494 * handle threads on other CPU's for now. 2495 */ 2496 if (td == curthread && PCPU_GET(spinlocks) != NULL) 2497 witness_list_locks(PCPU_PTR(spinlocks), db_printf); 2498 } 2499 2500 DB_SHOW_COMMAND(locks, db_witness_list) 2501 { 2502 struct thread *td; 2503 2504 if (have_addr) 2505 td = db_lookup_thread(addr, true); 2506 else 2507 td = kdb_thread; 2508 witness_ddb_list(td); 2509 } 2510 2511 DB_SHOW_ALL_COMMAND(locks, db_witness_list_all) 2512 { 2513 struct thread *td; 2514 struct proc *p; 2515 2516 /* 2517 * It would be nice to list only threads and processes that actually 2518 * held sleep locks, but that information is currently not exported 2519 * by WITNESS. 2520 */ 2521 FOREACH_PROC_IN_SYSTEM(p) { 2522 if (!witness_proc_has_locks(p)) 2523 continue; 2524 FOREACH_THREAD_IN_PROC(p, td) { 2525 if (!witness_thread_has_locks(td)) 2526 continue; 2527 db_printf("Process %d (%s) thread %p (%d)\n", p->p_pid, 2528 p->p_comm, td, td->td_tid); 2529 witness_ddb_list(td); 2530 if (db_pager_quit) 2531 return; 2532 } 2533 } 2534 } 2535 DB_SHOW_ALIAS(alllocks, db_witness_list_all) 2536 2537 DB_SHOW_COMMAND(witness, db_witness_display) 2538 { 2539 2540 witness_ddb_display(db_printf); 2541 } 2542 #endif 2543 2544 static void 2545 sbuf_print_witness_badstacks(struct sbuf *sb, size_t *oldidx) 2546 { 2547 struct witness_lock_order_data *data1, *data2, *tmp_data1, *tmp_data2; 2548 struct witness *tmp_w1, *tmp_w2, *w1, *w2; 2549 u_int w_rmatrix1, w_rmatrix2; 2550 int generation, i, j; 2551 2552 tmp_data1 = NULL; 2553 tmp_data2 = NULL; 2554 tmp_w1 = NULL; 2555 tmp_w2 = NULL; 2556 2557 /* Allocate and init temporary storage space. */ 2558 tmp_w1 = malloc(sizeof(struct witness), M_TEMP, M_WAITOK | M_ZERO); 2559 tmp_w2 = malloc(sizeof(struct witness), M_TEMP, M_WAITOK | M_ZERO); 2560 tmp_data1 = malloc(sizeof(struct witness_lock_order_data), M_TEMP, 2561 M_WAITOK | M_ZERO); 2562 tmp_data2 = malloc(sizeof(struct witness_lock_order_data), M_TEMP, 2563 M_WAITOK | M_ZERO); 2564 stack_zero(&tmp_data1->wlod_stack); 2565 stack_zero(&tmp_data2->wlod_stack); 2566 2567 restart: 2568 mtx_lock_spin(&w_mtx); 2569 generation = w_generation; 2570 mtx_unlock_spin(&w_mtx); 2571 sbuf_printf(sb, "Number of known direct relationships is %d\n", 2572 w_lohash.wloh_count); 2573 for (i = 1; i < w_max_used_index; i++) { 2574 mtx_lock_spin(&w_mtx); 2575 if (generation != w_generation) { 2576 mtx_unlock_spin(&w_mtx); 2577 2578 /* The graph has changed, try again. */ 2579 *oldidx = 0; 2580 sbuf_clear(sb); 2581 goto restart; 2582 } 2583 2584 w1 = &w_data[i]; 2585 if (w1->w_reversed == 0) { 2586 mtx_unlock_spin(&w_mtx); 2587 continue; 2588 } 2589 2590 /* Copy w1 locally so we can release the spin lock. */ 2591 *tmp_w1 = *w1; 2592 mtx_unlock_spin(&w_mtx); 2593 2594 if (tmp_w1->w_reversed == 0) 2595 continue; 2596 for (j = 1; j < w_max_used_index; j++) { 2597 if ((w_rmatrix[i][j] & WITNESS_REVERSAL) == 0 || i > j) 2598 continue; 2599 2600 mtx_lock_spin(&w_mtx); 2601 if (generation != w_generation) { 2602 mtx_unlock_spin(&w_mtx); 2603 2604 /* The graph has changed, try again. */ 2605 *oldidx = 0; 2606 sbuf_clear(sb); 2607 goto restart; 2608 } 2609 2610 w2 = &w_data[j]; 2611 data1 = witness_lock_order_get(w1, w2); 2612 data2 = witness_lock_order_get(w2, w1); 2613 2614 /* 2615 * Copy information locally so we can release the 2616 * spin lock. 2617 */ 2618 *tmp_w2 = *w2; 2619 w_rmatrix1 = (unsigned int)w_rmatrix[i][j]; 2620 w_rmatrix2 = (unsigned int)w_rmatrix[j][i]; 2621 2622 if (data1) { 2623 stack_zero(&tmp_data1->wlod_stack); 2624 stack_copy(&data1->wlod_stack, 2625 &tmp_data1->wlod_stack); 2626 } 2627 if (data2 && data2 != data1) { 2628 stack_zero(&tmp_data2->wlod_stack); 2629 stack_copy(&data2->wlod_stack, 2630 &tmp_data2->wlod_stack); 2631 } 2632 mtx_unlock_spin(&w_mtx); 2633 2634 sbuf_printf(sb, 2635 "\nLock order reversal between \"%s\"(%s) and \"%s\"(%s)!\n", 2636 tmp_w1->w_name, tmp_w1->w_class->lc_name, 2637 tmp_w2->w_name, tmp_w2->w_class->lc_name); 2638 if (data1) { 2639 sbuf_printf(sb, 2640 "Lock order \"%s\"(%s) -> \"%s\"(%s) first seen at:\n", 2641 tmp_w1->w_name, tmp_w1->w_class->lc_name, 2642 tmp_w2->w_name, tmp_w2->w_class->lc_name); 2643 stack_sbuf_print(sb, &tmp_data1->wlod_stack); 2644 sbuf_printf(sb, "\n"); 2645 } 2646 if (data2 && data2 != data1) { 2647 sbuf_printf(sb, 2648 "Lock order \"%s\"(%s) -> \"%s\"(%s) first seen at:\n", 2649 tmp_w2->w_name, tmp_w2->w_class->lc_name, 2650 tmp_w1->w_name, tmp_w1->w_class->lc_name); 2651 stack_sbuf_print(sb, &tmp_data2->wlod_stack); 2652 sbuf_printf(sb, "\n"); 2653 } 2654 } 2655 } 2656 mtx_lock_spin(&w_mtx); 2657 if (generation != w_generation) { 2658 mtx_unlock_spin(&w_mtx); 2659 2660 /* 2661 * The graph changed while we were printing stack data, 2662 * try again. 2663 */ 2664 *oldidx = 0; 2665 sbuf_clear(sb); 2666 goto restart; 2667 } 2668 mtx_unlock_spin(&w_mtx); 2669 2670 /* Free temporary storage space. */ 2671 free(tmp_data1, M_TEMP); 2672 free(tmp_data2, M_TEMP); 2673 free(tmp_w1, M_TEMP); 2674 free(tmp_w2, M_TEMP); 2675 } 2676 2677 static int 2678 sysctl_debug_witness_badstacks(SYSCTL_HANDLER_ARGS) 2679 { 2680 struct sbuf *sb; 2681 int error; 2682 2683 if (witness_watch < 1) { 2684 error = SYSCTL_OUT(req, w_notrunning, sizeof(w_notrunning)); 2685 return (error); 2686 } 2687 if (witness_cold) { 2688 error = SYSCTL_OUT(req, w_stillcold, sizeof(w_stillcold)); 2689 return (error); 2690 } 2691 error = 0; 2692 sb = sbuf_new(NULL, NULL, badstack_sbuf_size, SBUF_AUTOEXTEND); 2693 if (sb == NULL) 2694 return (ENOMEM); 2695 2696 sbuf_print_witness_badstacks(sb, &req->oldidx); 2697 2698 sbuf_finish(sb); 2699 error = SYSCTL_OUT(req, sbuf_data(sb), sbuf_len(sb) + 1); 2700 sbuf_delete(sb); 2701 2702 return (error); 2703 } 2704 2705 #ifdef DDB 2706 static int 2707 sbuf_db_printf_drain(void *arg __unused, const char *data, int len) 2708 { 2709 2710 return (db_printf("%.*s", len, data)); 2711 } 2712 2713 DB_SHOW_COMMAND(badstacks, db_witness_badstacks) 2714 { 2715 struct sbuf sb; 2716 char buffer[128]; 2717 size_t dummy; 2718 2719 sbuf_new(&sb, buffer, sizeof(buffer), SBUF_FIXEDLEN); 2720 sbuf_set_drain(&sb, sbuf_db_printf_drain, NULL); 2721 sbuf_print_witness_badstacks(&sb, &dummy); 2722 sbuf_finish(&sb); 2723 } 2724 #endif 2725 2726 static int 2727 sysctl_debug_witness_channel(SYSCTL_HANDLER_ARGS) 2728 { 2729 static const struct { 2730 enum witness_channel channel; 2731 const char *name; 2732 } channels[] = { 2733 { WITNESS_CONSOLE, "console" }, 2734 { WITNESS_LOG, "log" }, 2735 { WITNESS_NONE, "none" }, 2736 }; 2737 char buf[16]; 2738 u_int i; 2739 int error; 2740 2741 buf[0] = '\0'; 2742 for (i = 0; i < nitems(channels); i++) 2743 if (witness_channel == channels[i].channel) { 2744 snprintf(buf, sizeof(buf), "%s", channels[i].name); 2745 break; 2746 } 2747 2748 error = sysctl_handle_string(oidp, buf, sizeof(buf), req); 2749 if (error != 0 || req->newptr == NULL) 2750 return (error); 2751 2752 error = EINVAL; 2753 for (i = 0; i < nitems(channels); i++) 2754 if (strcmp(channels[i].name, buf) == 0) { 2755 witness_channel = channels[i].channel; 2756 error = 0; 2757 break; 2758 } 2759 return (error); 2760 } 2761 2762 static int 2763 sysctl_debug_witness_fullgraph(SYSCTL_HANDLER_ARGS) 2764 { 2765 struct witness *w; 2766 struct sbuf *sb; 2767 int error; 2768 2769 if (witness_watch < 1) { 2770 error = SYSCTL_OUT(req, w_notrunning, sizeof(w_notrunning)); 2771 return (error); 2772 } 2773 if (witness_cold) { 2774 error = SYSCTL_OUT(req, w_stillcold, sizeof(w_stillcold)); 2775 return (error); 2776 } 2777 error = 0; 2778 2779 error = sysctl_wire_old_buffer(req, 0); 2780 if (error != 0) 2781 return (error); 2782 sb = sbuf_new_for_sysctl(NULL, NULL, FULLGRAPH_SBUF_SIZE, req); 2783 if (sb == NULL) 2784 return (ENOMEM); 2785 sbuf_printf(sb, "\n"); 2786 2787 mtx_lock_spin(&w_mtx); 2788 STAILQ_FOREACH(w, &w_all, w_list) 2789 w->w_displayed = 0; 2790 STAILQ_FOREACH(w, &w_all, w_list) 2791 witness_add_fullgraph(sb, w); 2792 mtx_unlock_spin(&w_mtx); 2793 2794 /* 2795 * Close the sbuf and return to userland. 2796 */ 2797 error = sbuf_finish(sb); 2798 sbuf_delete(sb); 2799 2800 return (error); 2801 } 2802 2803 static int 2804 sysctl_debug_witness_watch(SYSCTL_HANDLER_ARGS) 2805 { 2806 int error, value; 2807 2808 value = witness_watch; 2809 error = sysctl_handle_int(oidp, &value, 0, req); 2810 if (error != 0 || req->newptr == NULL) 2811 return (error); 2812 if (value > 1 || value < -1 || 2813 (witness_watch == -1 && value != witness_watch)) 2814 return (EINVAL); 2815 witness_watch = value; 2816 return (0); 2817 } 2818 2819 static void 2820 witness_add_fullgraph(struct sbuf *sb, struct witness *w) 2821 { 2822 int i; 2823 2824 if (w->w_displayed != 0 || (w->w_file == NULL && w->w_line == 0)) 2825 return; 2826 w->w_displayed = 1; 2827 2828 WITNESS_INDEX_ASSERT(w->w_index); 2829 for (i = 1; i <= w_max_used_index; i++) { 2830 if (w_rmatrix[w->w_index][i] & WITNESS_PARENT) { 2831 sbuf_printf(sb, "\"%s\",\"%s\"\n", w->w_name, 2832 w_data[i].w_name); 2833 witness_add_fullgraph(sb, &w_data[i]); 2834 } 2835 } 2836 } 2837 2838 /* 2839 * A simple hash function. Takes a key pointer and a key size. If size == 0, 2840 * interprets the key as a string and reads until the null 2841 * terminator. Otherwise, reads the first size bytes. Returns an unsigned 32-bit 2842 * hash value computed from the key. 2843 */ 2844 static uint32_t 2845 witness_hash_djb2(const uint8_t *key, uint32_t size) 2846 { 2847 unsigned int hash = 5381; 2848 int i; 2849 2850 /* hash = hash * 33 + key[i] */ 2851 if (size) 2852 for (i = 0; i < size; i++) 2853 hash = ((hash << 5) + hash) + (unsigned int)key[i]; 2854 else 2855 for (i = 0; key[i] != 0; i++) 2856 hash = ((hash << 5) + hash) + (unsigned int)key[i]; 2857 2858 return (hash); 2859 } 2860 2861 2862 /* 2863 * Initializes the two witness hash tables. Called exactly once from 2864 * witness_initialize(). 2865 */ 2866 static void 2867 witness_init_hash_tables(void) 2868 { 2869 int i; 2870 2871 MPASS(witness_cold); 2872 2873 /* Initialize the hash tables. */ 2874 for (i = 0; i < WITNESS_HASH_SIZE; i++) 2875 w_hash.wh_array[i] = NULL; 2876 2877 w_hash.wh_size = WITNESS_HASH_SIZE; 2878 w_hash.wh_count = 0; 2879 2880 /* Initialize the lock order data hash. */ 2881 w_lofree = NULL; 2882 for (i = 0; i < WITNESS_LO_DATA_COUNT; i++) { 2883 memset(&w_lodata[i], 0, sizeof(w_lodata[i])); 2884 w_lodata[i].wlod_next = w_lofree; 2885 w_lofree = &w_lodata[i]; 2886 } 2887 w_lohash.wloh_size = WITNESS_LO_HASH_SIZE; 2888 w_lohash.wloh_count = 0; 2889 for (i = 0; i < WITNESS_LO_HASH_SIZE; i++) 2890 w_lohash.wloh_array[i] = NULL; 2891 } 2892 2893 static struct witness * 2894 witness_hash_get(const char *key) 2895 { 2896 struct witness *w; 2897 uint32_t hash; 2898 2899 MPASS(key != NULL); 2900 if (witness_cold == 0) 2901 mtx_assert(&w_mtx, MA_OWNED); 2902 hash = witness_hash_djb2(key, 0) % w_hash.wh_size; 2903 w = w_hash.wh_array[hash]; 2904 while (w != NULL) { 2905 if (strcmp(w->w_name, key) == 0) 2906 goto out; 2907 w = w->w_hash_next; 2908 } 2909 2910 out: 2911 return (w); 2912 } 2913 2914 static void 2915 witness_hash_put(struct witness *w) 2916 { 2917 uint32_t hash; 2918 2919 MPASS(w != NULL); 2920 MPASS(w->w_name != NULL); 2921 if (witness_cold == 0) 2922 mtx_assert(&w_mtx, MA_OWNED); 2923 KASSERT(witness_hash_get(w->w_name) == NULL, 2924 ("%s: trying to add a hash entry that already exists!", __func__)); 2925 KASSERT(w->w_hash_next == NULL, 2926 ("%s: w->w_hash_next != NULL", __func__)); 2927 2928 hash = witness_hash_djb2(w->w_name, 0) % w_hash.wh_size; 2929 w->w_hash_next = w_hash.wh_array[hash]; 2930 w_hash.wh_array[hash] = w; 2931 w_hash.wh_count++; 2932 } 2933 2934 2935 static struct witness_lock_order_data * 2936 witness_lock_order_get(struct witness *parent, struct witness *child) 2937 { 2938 struct witness_lock_order_data *data = NULL; 2939 struct witness_lock_order_key key; 2940 unsigned int hash; 2941 2942 MPASS(parent != NULL && child != NULL); 2943 key.from = parent->w_index; 2944 key.to = child->w_index; 2945 WITNESS_INDEX_ASSERT(key.from); 2946 WITNESS_INDEX_ASSERT(key.to); 2947 if ((w_rmatrix[parent->w_index][child->w_index] 2948 & WITNESS_LOCK_ORDER_KNOWN) == 0) 2949 goto out; 2950 2951 hash = witness_hash_djb2((const char*)&key, 2952 sizeof(key)) % w_lohash.wloh_size; 2953 data = w_lohash.wloh_array[hash]; 2954 while (data != NULL) { 2955 if (witness_lock_order_key_equal(&data->wlod_key, &key)) 2956 break; 2957 data = data->wlod_next; 2958 } 2959 2960 out: 2961 return (data); 2962 } 2963 2964 /* 2965 * Verify that parent and child have a known relationship, are not the same, 2966 * and child is actually a child of parent. This is done without w_mtx 2967 * to avoid contention in the common case. 2968 */ 2969 static int 2970 witness_lock_order_check(struct witness *parent, struct witness *child) 2971 { 2972 2973 if (parent != child && 2974 w_rmatrix[parent->w_index][child->w_index] 2975 & WITNESS_LOCK_ORDER_KNOWN && 2976 isitmychild(parent, child)) 2977 return (1); 2978 2979 return (0); 2980 } 2981 2982 static int 2983 witness_lock_order_add(struct witness *parent, struct witness *child) 2984 { 2985 struct witness_lock_order_data *data = NULL; 2986 struct witness_lock_order_key key; 2987 unsigned int hash; 2988 2989 MPASS(parent != NULL && child != NULL); 2990 key.from = parent->w_index; 2991 key.to = child->w_index; 2992 WITNESS_INDEX_ASSERT(key.from); 2993 WITNESS_INDEX_ASSERT(key.to); 2994 if (w_rmatrix[parent->w_index][child->w_index] 2995 & WITNESS_LOCK_ORDER_KNOWN) 2996 return (1); 2997 2998 hash = witness_hash_djb2((const char*)&key, 2999 sizeof(key)) % w_lohash.wloh_size; 3000 w_rmatrix[parent->w_index][child->w_index] |= WITNESS_LOCK_ORDER_KNOWN; 3001 data = w_lofree; 3002 if (data == NULL) 3003 return (0); 3004 w_lofree = data->wlod_next; 3005 data->wlod_next = w_lohash.wloh_array[hash]; 3006 data->wlod_key = key; 3007 w_lohash.wloh_array[hash] = data; 3008 w_lohash.wloh_count++; 3009 stack_zero(&data->wlod_stack); 3010 stack_save(&data->wlod_stack); 3011 return (1); 3012 } 3013 3014 /* Call this whenever the structure of the witness graph changes. */ 3015 static void 3016 witness_increment_graph_generation(void) 3017 { 3018 3019 if (witness_cold == 0) 3020 mtx_assert(&w_mtx, MA_OWNED); 3021 w_generation++; 3022 } 3023 3024 static int 3025 witness_output_drain(void *arg __unused, const char *data, int len) 3026 { 3027 3028 witness_output("%.*s", len, data); 3029 return (len); 3030 } 3031 3032 static void 3033 witness_debugger(int cond, const char *msg) 3034 { 3035 char buf[32]; 3036 struct sbuf sb; 3037 struct stack st; 3038 3039 if (!cond) 3040 return; 3041 3042 if (witness_trace) { 3043 sbuf_new(&sb, buf, sizeof(buf), SBUF_FIXEDLEN); 3044 sbuf_set_drain(&sb, witness_output_drain, NULL); 3045 3046 stack_zero(&st); 3047 stack_save(&st); 3048 witness_output("stack backtrace:\n"); 3049 stack_sbuf_print_ddb(&sb, &st); 3050 3051 sbuf_finish(&sb); 3052 } 3053 3054 #ifdef KDB 3055 if (witness_kdb) 3056 kdb_enter(KDB_WHY_WITNESS, msg); 3057 #endif 3058 } 3059