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 #ifndef WITNESS_COUNT 136 #define WITNESS_COUNT 1536 137 #endif 138 #define WITNESS_HASH_SIZE 251 /* Prime, gives load factor < 2 */ 139 #define WITNESS_PENDLIST (512 + (MAXCPU * 4)) 140 141 /* Allocate 256 KB of stack data space */ 142 #define WITNESS_LO_DATA_COUNT 2048 143 144 /* Prime, gives load factor of ~2 at full load */ 145 #define WITNESS_LO_HASH_SIZE 1021 146 147 /* 148 * XXX: This is somewhat bogus, as we assume here that at most 2048 threads 149 * will hold LOCK_NCHILDREN locks. We handle failure ok, and we should 150 * probably be safe for the most part, but it's still a SWAG. 151 */ 152 #define LOCK_NCHILDREN 5 153 #define LOCK_CHILDCOUNT 2048 154 155 #define MAX_W_NAME 64 156 157 #define FULLGRAPH_SBUF_SIZE 512 158 159 /* 160 * These flags go in the witness relationship matrix and describe the 161 * relationship between any two struct witness objects. 162 */ 163 #define WITNESS_UNRELATED 0x00 /* No lock order relation. */ 164 #define WITNESS_PARENT 0x01 /* Parent, aka direct ancestor. */ 165 #define WITNESS_ANCESTOR 0x02 /* Direct or indirect ancestor. */ 166 #define WITNESS_CHILD 0x04 /* Child, aka direct descendant. */ 167 #define WITNESS_DESCENDANT 0x08 /* Direct or indirect descendant. */ 168 #define WITNESS_ANCESTOR_MASK (WITNESS_PARENT | WITNESS_ANCESTOR) 169 #define WITNESS_DESCENDANT_MASK (WITNESS_CHILD | WITNESS_DESCENDANT) 170 #define WITNESS_RELATED_MASK \ 171 (WITNESS_ANCESTOR_MASK | WITNESS_DESCENDANT_MASK) 172 #define WITNESS_REVERSAL 0x10 /* A lock order reversal has been 173 * observed. */ 174 #define WITNESS_RESERVED1 0x20 /* Unused flag, reserved. */ 175 #define WITNESS_RESERVED2 0x40 /* Unused flag, reserved. */ 176 #define WITNESS_LOCK_ORDER_KNOWN 0x80 /* This lock order is known. */ 177 178 /* Descendant to ancestor flags */ 179 #define WITNESS_DTOA(x) (((x) & WITNESS_RELATED_MASK) >> 2) 180 181 /* Ancestor to descendant flags */ 182 #define WITNESS_ATOD(x) (((x) & WITNESS_RELATED_MASK) << 2) 183 184 #define WITNESS_INDEX_ASSERT(i) \ 185 MPASS((i) > 0 && (i) <= w_max_used_index && (i) < witness_count) 186 187 static MALLOC_DEFINE(M_WITNESS, "Witness", "Witness"); 188 189 /* 190 * Lock instances. A lock instance is the data associated with a lock while 191 * it is held by witness. For example, a lock instance will hold the 192 * recursion count of a lock. Lock instances are held in lists. Spin locks 193 * are held in a per-cpu list while sleep locks are held in per-thread list. 194 */ 195 struct lock_instance { 196 struct lock_object *li_lock; 197 const char *li_file; 198 int li_line; 199 u_int li_flags; 200 }; 201 202 /* 203 * A simple list type used to build the list of locks held by a thread 204 * or CPU. We can't simply embed the list in struct lock_object since a 205 * lock may be held by more than one thread if it is a shared lock. Locks 206 * are added to the head of the list, so we fill up each list entry from 207 * "the back" logically. To ease some of the arithmetic, we actually fill 208 * in each list entry the normal way (children[0] then children[1], etc.) but 209 * when we traverse the list we read children[count-1] as the first entry 210 * down to children[0] as the final entry. 211 */ 212 struct lock_list_entry { 213 struct lock_list_entry *ll_next; 214 struct lock_instance ll_children[LOCK_NCHILDREN]; 215 u_int ll_count; 216 }; 217 218 /* 219 * The main witness structure. One of these per named lock type in the system 220 * (for example, "vnode interlock"). 221 */ 222 struct witness { 223 char w_name[MAX_W_NAME]; 224 uint32_t w_index; /* Index in the relationship matrix */ 225 struct lock_class *w_class; 226 STAILQ_ENTRY(witness) w_list; /* List of all witnesses. */ 227 STAILQ_ENTRY(witness) w_typelist; /* Witnesses of a type. */ 228 struct witness *w_hash_next; /* Linked list in hash buckets. */ 229 const char *w_file; /* File where last acquired */ 230 uint32_t w_line; /* Line where last acquired */ 231 uint32_t w_refcount; 232 uint16_t w_num_ancestors; /* direct/indirect 233 * ancestor count */ 234 uint16_t w_num_descendants; /* direct/indirect 235 * descendant count */ 236 int16_t w_ddb_level; 237 unsigned w_displayed:1; 238 unsigned w_reversed:1; 239 }; 240 241 STAILQ_HEAD(witness_list, witness); 242 243 /* 244 * The witness hash table. Keys are witness names (const char *), elements are 245 * witness objects (struct witness *). 246 */ 247 struct witness_hash { 248 struct witness *wh_array[WITNESS_HASH_SIZE]; 249 uint32_t wh_size; 250 uint32_t wh_count; 251 }; 252 253 /* 254 * Key type for the lock order data hash table. 255 */ 256 struct witness_lock_order_key { 257 uint16_t from; 258 uint16_t to; 259 }; 260 261 struct witness_lock_order_data { 262 struct stack wlod_stack; 263 struct witness_lock_order_key wlod_key; 264 struct witness_lock_order_data *wlod_next; 265 }; 266 267 /* 268 * The witness lock order data hash table. Keys are witness index tuples 269 * (struct witness_lock_order_key), elements are lock order data objects 270 * (struct witness_lock_order_data). 271 */ 272 struct witness_lock_order_hash { 273 struct witness_lock_order_data *wloh_array[WITNESS_LO_HASH_SIZE]; 274 u_int wloh_size; 275 u_int wloh_count; 276 }; 277 278 struct witness_blessed { 279 const char *b_lock1; 280 const char *b_lock2; 281 }; 282 283 struct witness_pendhelp { 284 const char *wh_type; 285 struct lock_object *wh_lock; 286 }; 287 288 struct witness_order_list_entry { 289 const char *w_name; 290 struct lock_class *w_class; 291 }; 292 293 /* 294 * Returns 0 if one of the locks is a spin lock and the other is not. 295 * Returns 1 otherwise. 296 */ 297 static __inline int 298 witness_lock_type_equal(struct witness *w1, struct witness *w2) 299 { 300 301 return ((w1->w_class->lc_flags & (LC_SLEEPLOCK | LC_SPINLOCK)) == 302 (w2->w_class->lc_flags & (LC_SLEEPLOCK | LC_SPINLOCK))); 303 } 304 305 static __inline int 306 witness_lock_order_key_equal(const struct witness_lock_order_key *a, 307 const struct witness_lock_order_key *b) 308 { 309 310 return (a->from == b->from && a->to == b->to); 311 } 312 313 static int _isitmyx(struct witness *w1, struct witness *w2, int rmask, 314 const char *fname); 315 static void adopt(struct witness *parent, struct witness *child); 316 static int blessed(struct witness *, struct witness *); 317 static void depart(struct witness *w); 318 static struct witness *enroll(const char *description, 319 struct lock_class *lock_class); 320 static struct lock_instance *find_instance(struct lock_list_entry *list, 321 const struct lock_object *lock); 322 static int isitmychild(struct witness *parent, struct witness *child); 323 static int isitmydescendant(struct witness *parent, struct witness *child); 324 static void itismychild(struct witness *parent, struct witness *child); 325 static int sysctl_debug_witness_badstacks(SYSCTL_HANDLER_ARGS); 326 static int sysctl_debug_witness_watch(SYSCTL_HANDLER_ARGS); 327 static int sysctl_debug_witness_fullgraph(SYSCTL_HANDLER_ARGS); 328 static int sysctl_debug_witness_channel(SYSCTL_HANDLER_ARGS); 329 static void witness_add_fullgraph(struct sbuf *sb, struct witness *parent); 330 #ifdef DDB 331 static void witness_ddb_compute_levels(void); 332 static void witness_ddb_display(int(*)(const char *fmt, ...)); 333 static void witness_ddb_display_descendants(int(*)(const char *fmt, ...), 334 struct witness *, int indent); 335 static void witness_ddb_display_list(int(*prnt)(const char *fmt, ...), 336 struct witness_list *list); 337 static void witness_ddb_level_descendants(struct witness *parent, int l); 338 static void witness_ddb_list(struct thread *td); 339 #endif 340 static void witness_debugger(int cond, const char *msg); 341 static void witness_free(struct witness *m); 342 static struct witness *witness_get(void); 343 static uint32_t witness_hash_djb2(const uint8_t *key, uint32_t size); 344 static struct witness *witness_hash_get(const char *key); 345 static void witness_hash_put(struct witness *w); 346 static void witness_init_hash_tables(void); 347 static void witness_increment_graph_generation(void); 348 static void witness_lock_list_free(struct lock_list_entry *lle); 349 static struct lock_list_entry *witness_lock_list_get(void); 350 static int witness_lock_order_add(struct witness *parent, 351 struct witness *child); 352 static int witness_lock_order_check(struct witness *parent, 353 struct witness *child); 354 static struct witness_lock_order_data *witness_lock_order_get( 355 struct witness *parent, 356 struct witness *child); 357 static void witness_list_lock(struct lock_instance *instance, 358 int (*prnt)(const char *fmt, ...)); 359 static int witness_output(const char *fmt, ...) __printflike(1, 2); 360 static int witness_voutput(const char *fmt, va_list ap) __printflike(1, 0); 361 static void witness_setflag(struct lock_object *lock, int flag, int set); 362 363 static SYSCTL_NODE(_debug, OID_AUTO, witness, CTLFLAG_RW, NULL, 364 "Witness Locking"); 365 366 /* 367 * If set to 0, lock order checking is disabled. If set to -1, 368 * witness is completely disabled. Otherwise witness performs full 369 * lock order checking for all locks. At runtime, lock order checking 370 * may be toggled. However, witness cannot be reenabled once it is 371 * completely disabled. 372 */ 373 static int witness_watch = 1; 374 SYSCTL_PROC(_debug_witness, OID_AUTO, watch, CTLFLAG_RWTUN | CTLTYPE_INT, NULL, 0, 375 sysctl_debug_witness_watch, "I", "witness is watching lock operations"); 376 377 #ifdef KDB 378 /* 379 * When KDB is enabled and witness_kdb is 1, it will cause the system 380 * to drop into kdebug() when: 381 * - a lock hierarchy violation occurs 382 * - locks are held when going to sleep. 383 */ 384 #ifdef WITNESS_KDB 385 int witness_kdb = 1; 386 #else 387 int witness_kdb = 0; 388 #endif 389 SYSCTL_INT(_debug_witness, OID_AUTO, kdb, CTLFLAG_RWTUN, &witness_kdb, 0, ""); 390 #endif /* KDB */ 391 392 #if defined(DDB) || defined(KDB) 393 /* 394 * When DDB or KDB is enabled and witness_trace is 1, it will cause the system 395 * to print a stack trace: 396 * - a lock hierarchy violation occurs 397 * - locks are held when going to sleep. 398 */ 399 int witness_trace = 1; 400 SYSCTL_INT(_debug_witness, OID_AUTO, trace, CTLFLAG_RWTUN, &witness_trace, 0, ""); 401 #endif /* DDB || KDB */ 402 403 #ifdef WITNESS_SKIPSPIN 404 int witness_skipspin = 1; 405 #else 406 int witness_skipspin = 0; 407 #endif 408 SYSCTL_INT(_debug_witness, OID_AUTO, skipspin, CTLFLAG_RDTUN, &witness_skipspin, 0, ""); 409 410 int badstack_sbuf_size; 411 412 int witness_count = WITNESS_COUNT; 413 SYSCTL_INT(_debug_witness, OID_AUTO, witness_count, CTLFLAG_RDTUN, 414 &witness_count, 0, ""); 415 416 /* 417 * Output channel for witness messages. By default we print to the console. 418 */ 419 enum witness_channel { 420 WITNESS_CONSOLE, 421 WITNESS_LOG, 422 WITNESS_NONE, 423 }; 424 425 static enum witness_channel witness_channel = WITNESS_CONSOLE; 426 SYSCTL_PROC(_debug_witness, OID_AUTO, output_channel, CTLTYPE_STRING | 427 CTLFLAG_RWTUN, NULL, 0, sysctl_debug_witness_channel, "A", 428 "Output channel for warnings"); 429 430 /* 431 * Call this to print out the relations between locks. 432 */ 433 SYSCTL_PROC(_debug_witness, OID_AUTO, fullgraph, CTLTYPE_STRING | CTLFLAG_RD, 434 NULL, 0, sysctl_debug_witness_fullgraph, "A", "Show locks relation graphs"); 435 436 /* 437 * Call this to print out the witness faulty stacks. 438 */ 439 SYSCTL_PROC(_debug_witness, OID_AUTO, badstacks, CTLTYPE_STRING | CTLFLAG_RD, 440 NULL, 0, sysctl_debug_witness_badstacks, "A", "Show bad witness stacks"); 441 442 static struct mtx w_mtx; 443 444 /* w_list */ 445 static struct witness_list w_free = STAILQ_HEAD_INITIALIZER(w_free); 446 static struct witness_list w_all = STAILQ_HEAD_INITIALIZER(w_all); 447 448 /* w_typelist */ 449 static struct witness_list w_spin = STAILQ_HEAD_INITIALIZER(w_spin); 450 static struct witness_list w_sleep = STAILQ_HEAD_INITIALIZER(w_sleep); 451 452 /* lock list */ 453 static struct lock_list_entry *w_lock_list_free = NULL; 454 static struct witness_pendhelp pending_locks[WITNESS_PENDLIST]; 455 static u_int pending_cnt; 456 457 static int w_free_cnt, w_spin_cnt, w_sleep_cnt; 458 SYSCTL_INT(_debug_witness, OID_AUTO, free_cnt, CTLFLAG_RD, &w_free_cnt, 0, ""); 459 SYSCTL_INT(_debug_witness, OID_AUTO, spin_cnt, CTLFLAG_RD, &w_spin_cnt, 0, ""); 460 SYSCTL_INT(_debug_witness, OID_AUTO, sleep_cnt, CTLFLAG_RD, &w_sleep_cnt, 0, 461 ""); 462 463 static struct witness *w_data; 464 static uint8_t **w_rmatrix; 465 static struct lock_list_entry w_locklistdata[LOCK_CHILDCOUNT]; 466 static struct witness_hash w_hash; /* The witness hash table. */ 467 468 /* The lock order data hash */ 469 static struct witness_lock_order_data w_lodata[WITNESS_LO_DATA_COUNT]; 470 static struct witness_lock_order_data *w_lofree = NULL; 471 static struct witness_lock_order_hash w_lohash; 472 static int w_max_used_index = 0; 473 static unsigned int w_generation = 0; 474 static const char w_notrunning[] = "Witness not running\n"; 475 static const char w_stillcold[] = "Witness is still cold\n"; 476 #ifdef __i386__ 477 static const char w_notallowed[] = "The sysctl is disabled on the arch\n"; 478 #endif 479 480 static struct witness_order_list_entry order_lists[] = { 481 /* 482 * sx locks 483 */ 484 { "proctree", &lock_class_sx }, 485 { "allproc", &lock_class_sx }, 486 { "allprison", &lock_class_sx }, 487 { NULL, NULL }, 488 /* 489 * Various mutexes 490 */ 491 { "Giant", &lock_class_mtx_sleep }, 492 { "pipe mutex", &lock_class_mtx_sleep }, 493 { "sigio lock", &lock_class_mtx_sleep }, 494 { "process group", &lock_class_mtx_sleep }, 495 #ifdef HWPMC_HOOKS 496 { "pmc-sleep", &lock_class_mtx_sleep }, 497 #endif 498 { "process lock", &lock_class_mtx_sleep }, 499 { "session", &lock_class_mtx_sleep }, 500 { "uidinfo hash", &lock_class_rw }, 501 { "time lock", &lock_class_mtx_sleep }, 502 { NULL, NULL }, 503 /* 504 * umtx 505 */ 506 { "umtx lock", &lock_class_mtx_sleep }, 507 { NULL, NULL }, 508 /* 509 * Sockets 510 */ 511 { "accept", &lock_class_mtx_sleep }, 512 { "so_snd", &lock_class_mtx_sleep }, 513 { "so_rcv", &lock_class_mtx_sleep }, 514 { "sellck", &lock_class_mtx_sleep }, 515 { NULL, NULL }, 516 /* 517 * Routing 518 */ 519 { "so_rcv", &lock_class_mtx_sleep }, 520 { "radix node head", &lock_class_rm }, 521 { "rtentry", &lock_class_mtx_sleep }, 522 { "ifaddr", &lock_class_mtx_sleep }, 523 { NULL, NULL }, 524 /* 525 * IPv4 multicast: 526 * protocol locks before interface locks, after UDP locks. 527 */ 528 { "in_multi_sx", &lock_class_sx }, 529 { "udpinp", &lock_class_rw }, 530 { "in_multi_list_mtx", &lock_class_mtx_sleep }, 531 { "igmp_mtx", &lock_class_mtx_sleep }, 532 { "ifnet_rw", &lock_class_rw }, 533 { "if_addr_lock", &lock_class_mtx_sleep }, 534 { NULL, NULL }, 535 /* 536 * IPv6 multicast: 537 * protocol locks before interface locks, after UDP locks. 538 */ 539 { "in6_multi_sx", &lock_class_sx }, 540 { "udpinp", &lock_class_rw }, 541 { "in6_multi_list_mtx", &lock_class_mtx_sleep }, 542 { "mld_mtx", &lock_class_mtx_sleep }, 543 { "ifnet_rw", &lock_class_rw }, 544 { "if_addr_lock", &lock_class_mtx_sleep }, 545 { NULL, NULL }, 546 /* 547 * UNIX Domain Sockets 548 */ 549 { "unp_link_rwlock", &lock_class_rw }, 550 { "unp_list_lock", &lock_class_mtx_sleep }, 551 { "unp", &lock_class_mtx_sleep }, 552 { "so_snd", &lock_class_mtx_sleep }, 553 { NULL, NULL }, 554 /* 555 * UDP/IP 556 */ 557 { "udp", &lock_class_mtx_sleep }, 558 { "udpinp", &lock_class_rw }, 559 { "so_snd", &lock_class_mtx_sleep }, 560 { NULL, NULL }, 561 /* 562 * TCP/IP 563 */ 564 { "tcp", &lock_class_mtx_sleep }, 565 { "tcpinp", &lock_class_rw }, 566 { "so_snd", &lock_class_mtx_sleep }, 567 { NULL, NULL }, 568 /* 569 * BPF 570 */ 571 { "bpf global lock", &lock_class_sx }, 572 { "bpf cdev lock", &lock_class_mtx_sleep }, 573 { NULL, NULL }, 574 /* 575 * NFS server 576 */ 577 { "nfsd_mtx", &lock_class_mtx_sleep }, 578 { "so_snd", &lock_class_mtx_sleep }, 579 { NULL, NULL }, 580 581 /* 582 * IEEE 802.11 583 */ 584 { "802.11 com lock", &lock_class_mtx_sleep}, 585 { NULL, NULL }, 586 /* 587 * Network drivers 588 */ 589 { "network driver", &lock_class_mtx_sleep}, 590 { NULL, NULL }, 591 592 /* 593 * Netgraph 594 */ 595 { "ng_node", &lock_class_mtx_sleep }, 596 { "ng_worklist", &lock_class_mtx_sleep }, 597 { NULL, NULL }, 598 /* 599 * CDEV 600 */ 601 { "vm map (system)", &lock_class_mtx_sleep }, 602 { "vnode interlock", &lock_class_mtx_sleep }, 603 { "cdev", &lock_class_mtx_sleep }, 604 { NULL, NULL }, 605 /* 606 * VM 607 */ 608 { "vm map (user)", &lock_class_sx }, 609 { "vm object", &lock_class_rw }, 610 { "vm page", &lock_class_mtx_sleep }, 611 { "pmap pv global", &lock_class_rw }, 612 { "pmap", &lock_class_mtx_sleep }, 613 { "pmap pv list", &lock_class_rw }, 614 { "vm page free queue", &lock_class_mtx_sleep }, 615 { "vm pagequeue", &lock_class_mtx_sleep }, 616 { NULL, NULL }, 617 /* 618 * kqueue/VFS interaction 619 */ 620 { "kqueue", &lock_class_mtx_sleep }, 621 { "struct mount mtx", &lock_class_mtx_sleep }, 622 { "vnode interlock", &lock_class_mtx_sleep }, 623 { NULL, NULL }, 624 /* 625 * VFS namecache 626 */ 627 { "ncvn", &lock_class_mtx_sleep }, 628 { "ncbuc", &lock_class_rw }, 629 { "vnode interlock", &lock_class_mtx_sleep }, 630 { "ncneg", &lock_class_mtx_sleep }, 631 { NULL, NULL }, 632 /* 633 * ZFS locking 634 */ 635 { "dn->dn_mtx", &lock_class_sx }, 636 { "dr->dt.di.dr_mtx", &lock_class_sx }, 637 { "db->db_mtx", &lock_class_sx }, 638 { NULL, NULL }, 639 /* 640 * TCP log locks 641 */ 642 { "TCP ID tree", &lock_class_rw }, 643 { "tcp log id bucket", &lock_class_mtx_sleep }, 644 { "tcpinp", &lock_class_rw }, 645 { "TCP log expireq", &lock_class_mtx_sleep }, 646 { NULL, NULL }, 647 /* 648 * spin locks 649 */ 650 #ifdef SMP 651 { "ap boot", &lock_class_mtx_spin }, 652 #endif 653 { "rm.mutex_mtx", &lock_class_mtx_spin }, 654 { "sio", &lock_class_mtx_spin }, 655 #ifdef __i386__ 656 { "cy", &lock_class_mtx_spin }, 657 #endif 658 #ifdef __sparc64__ 659 { "pcib_mtx", &lock_class_mtx_spin }, 660 { "rtc_mtx", &lock_class_mtx_spin }, 661 #endif 662 { "scc_hwmtx", &lock_class_mtx_spin }, 663 { "uart_hwmtx", &lock_class_mtx_spin }, 664 { "fast_taskqueue", &lock_class_mtx_spin }, 665 { "intr table", &lock_class_mtx_spin }, 666 { "process slock", &lock_class_mtx_spin }, 667 { "syscons video lock", &lock_class_mtx_spin }, 668 { "sleepq chain", &lock_class_mtx_spin }, 669 { "rm_spinlock", &lock_class_mtx_spin }, 670 { "turnstile chain", &lock_class_mtx_spin }, 671 { "turnstile lock", &lock_class_mtx_spin }, 672 { "sched lock", &lock_class_mtx_spin }, 673 { "td_contested", &lock_class_mtx_spin }, 674 { "callout", &lock_class_mtx_spin }, 675 { "entropy harvest mutex", &lock_class_mtx_spin }, 676 #ifdef SMP 677 { "smp rendezvous", &lock_class_mtx_spin }, 678 #endif 679 #ifdef __powerpc__ 680 { "tlb0", &lock_class_mtx_spin }, 681 #endif 682 { NULL, NULL }, 683 { "sched lock", &lock_class_mtx_spin }, 684 #ifdef HWPMC_HOOKS 685 { "pmc-per-proc", &lock_class_mtx_spin }, 686 #endif 687 { NULL, NULL }, 688 /* 689 * leaf locks 690 */ 691 { "intrcnt", &lock_class_mtx_spin }, 692 { "icu", &lock_class_mtx_spin }, 693 #if defined(SMP) && defined(__sparc64__) 694 { "ipi", &lock_class_mtx_spin }, 695 #endif 696 #ifdef __i386__ 697 { "allpmaps", &lock_class_mtx_spin }, 698 { "descriptor tables", &lock_class_mtx_spin }, 699 #endif 700 { "clk", &lock_class_mtx_spin }, 701 { "cpuset", &lock_class_mtx_spin }, 702 { "mprof lock", &lock_class_mtx_spin }, 703 { "zombie lock", &lock_class_mtx_spin }, 704 { "ALD Queue", &lock_class_mtx_spin }, 705 #if defined(__i386__) || defined(__amd64__) 706 { "pcicfg", &lock_class_mtx_spin }, 707 { "NDIS thread lock", &lock_class_mtx_spin }, 708 #endif 709 { "tw_osl_io_lock", &lock_class_mtx_spin }, 710 { "tw_osl_q_lock", &lock_class_mtx_spin }, 711 { "tw_cl_io_lock", &lock_class_mtx_spin }, 712 { "tw_cl_intr_lock", &lock_class_mtx_spin }, 713 { "tw_cl_gen_lock", &lock_class_mtx_spin }, 714 #ifdef HWPMC_HOOKS 715 { "pmc-leaf", &lock_class_mtx_spin }, 716 #endif 717 { "blocked lock", &lock_class_mtx_spin }, 718 { NULL, NULL }, 719 { NULL, NULL } 720 }; 721 722 /* 723 * Pairs of locks which have been blessed. Witness does not complain about 724 * order problems with blessed lock pairs. Please do not add an entry to the 725 * table without an explanatory comment. 726 */ 727 static struct witness_blessed blessed_list[] = { 728 /* 729 * See the comment in ufs_dirhash.c. Basically, a vnode lock serializes 730 * both lock orders, so a deadlock cannot happen as a result of this 731 * LOR. 732 */ 733 { "dirhash", "bufwait" }, 734 735 /* 736 * A UFS vnode may be locked in vget() while a buffer belonging to the 737 * parent directory vnode is locked. 738 */ 739 { "ufs", "bufwait" }, 740 }; 741 742 /* 743 * This global is set to 0 once it becomes safe to use the witness code. 744 */ 745 static int witness_cold = 1; 746 747 /* 748 * This global is set to 1 once the static lock orders have been enrolled 749 * so that a warning can be issued for any spin locks enrolled later. 750 */ 751 static int witness_spin_warn = 0; 752 753 /* Trim useless garbage from filenames. */ 754 static const char * 755 fixup_filename(const char *file) 756 { 757 758 if (file == NULL) 759 return (NULL); 760 while (strncmp(file, "../", 3) == 0) 761 file += 3; 762 return (file); 763 } 764 765 /* 766 * Calculate the size of early witness structures. 767 */ 768 int 769 witness_startup_count(void) 770 { 771 int sz; 772 773 sz = sizeof(struct witness) * witness_count; 774 sz += sizeof(*w_rmatrix) * (witness_count + 1); 775 sz += sizeof(*w_rmatrix[0]) * (witness_count + 1) * 776 (witness_count + 1); 777 778 return (sz); 779 } 780 781 /* 782 * The WITNESS-enabled diagnostic code. Note that the witness code does 783 * assume that the early boot is single-threaded at least until after this 784 * routine is completed. 785 */ 786 void 787 witness_startup(void *mem) 788 { 789 struct lock_object *lock; 790 struct witness_order_list_entry *order; 791 struct witness *w, *w1; 792 uintptr_t p; 793 int i; 794 795 p = (uintptr_t)mem; 796 w_data = (void *)p; 797 p += sizeof(struct witness) * witness_count; 798 799 w_rmatrix = (void *)p; 800 p += sizeof(*w_rmatrix) * (witness_count + 1); 801 802 for (i = 0; i < witness_count + 1; i++) { 803 w_rmatrix[i] = (void *)p; 804 p += sizeof(*w_rmatrix[i]) * (witness_count + 1); 805 } 806 badstack_sbuf_size = witness_count * 256; 807 808 /* 809 * We have to release Giant before initializing its witness 810 * structure so that WITNESS doesn't get confused. 811 */ 812 mtx_unlock(&Giant); 813 mtx_assert(&Giant, MA_NOTOWNED); 814 815 CTR1(KTR_WITNESS, "%s: initializing witness", __func__); 816 mtx_init(&w_mtx, "witness lock", NULL, MTX_SPIN | MTX_QUIET | 817 MTX_NOWITNESS | MTX_NOPROFILE); 818 for (i = witness_count - 1; i >= 0; i--) { 819 w = &w_data[i]; 820 memset(w, 0, sizeof(*w)); 821 w_data[i].w_index = i; /* Witness index never changes. */ 822 witness_free(w); 823 } 824 KASSERT(STAILQ_FIRST(&w_free)->w_index == 0, 825 ("%s: Invalid list of free witness objects", __func__)); 826 827 /* Witness with index 0 is not used to aid in debugging. */ 828 STAILQ_REMOVE_HEAD(&w_free, w_list); 829 w_free_cnt--; 830 831 for (i = 0; i < witness_count; i++) { 832 memset(w_rmatrix[i], 0, sizeof(*w_rmatrix[i]) * 833 (witness_count + 1)); 834 } 835 836 for (i = 0; i < LOCK_CHILDCOUNT; i++) 837 witness_lock_list_free(&w_locklistdata[i]); 838 witness_init_hash_tables(); 839 840 /* First add in all the specified order lists. */ 841 for (order = order_lists; order->w_name != NULL; order++) { 842 w = enroll(order->w_name, order->w_class); 843 if (w == NULL) 844 continue; 845 w->w_file = "order list"; 846 for (order++; order->w_name != NULL; order++) { 847 w1 = enroll(order->w_name, order->w_class); 848 if (w1 == NULL) 849 continue; 850 w1->w_file = "order list"; 851 itismychild(w, w1); 852 w = w1; 853 } 854 } 855 witness_spin_warn = 1; 856 857 /* Iterate through all locks and add them to witness. */ 858 for (i = 0; pending_locks[i].wh_lock != NULL; i++) { 859 lock = pending_locks[i].wh_lock; 860 KASSERT(lock->lo_flags & LO_WITNESS, 861 ("%s: lock %s is on pending list but not LO_WITNESS", 862 __func__, lock->lo_name)); 863 lock->lo_witness = enroll(pending_locks[i].wh_type, 864 LOCK_CLASS(lock)); 865 } 866 867 /* Mark the witness code as being ready for use. */ 868 witness_cold = 0; 869 870 mtx_lock(&Giant); 871 } 872 873 void 874 witness_init(struct lock_object *lock, const char *type) 875 { 876 struct lock_class *class; 877 878 /* Various sanity checks. */ 879 class = LOCK_CLASS(lock); 880 if ((lock->lo_flags & LO_RECURSABLE) != 0 && 881 (class->lc_flags & LC_RECURSABLE) == 0) 882 kassert_panic("%s: lock (%s) %s can not be recursable", 883 __func__, class->lc_name, lock->lo_name); 884 if ((lock->lo_flags & LO_SLEEPABLE) != 0 && 885 (class->lc_flags & LC_SLEEPABLE) == 0) 886 kassert_panic("%s: lock (%s) %s can not be sleepable", 887 __func__, class->lc_name, lock->lo_name); 888 if ((lock->lo_flags & LO_UPGRADABLE) != 0 && 889 (class->lc_flags & LC_UPGRADABLE) == 0) 890 kassert_panic("%s: lock (%s) %s can not be upgradable", 891 __func__, class->lc_name, lock->lo_name); 892 893 /* 894 * If we shouldn't watch this lock, then just clear lo_witness. 895 * Otherwise, if witness_cold is set, then it is too early to 896 * enroll this lock, so defer it to witness_initialize() by adding 897 * it to the pending_locks list. If it is not too early, then enroll 898 * the lock now. 899 */ 900 if (witness_watch < 1 || panicstr != NULL || 901 (lock->lo_flags & LO_WITNESS) == 0) 902 lock->lo_witness = NULL; 903 else if (witness_cold) { 904 pending_locks[pending_cnt].wh_lock = lock; 905 pending_locks[pending_cnt++].wh_type = type; 906 if (pending_cnt > WITNESS_PENDLIST) 907 panic("%s: pending locks list is too small, " 908 "increase WITNESS_PENDLIST\n", 909 __func__); 910 } else 911 lock->lo_witness = enroll(type, class); 912 } 913 914 void 915 witness_destroy(struct lock_object *lock) 916 { 917 struct lock_class *class; 918 struct witness *w; 919 920 class = LOCK_CLASS(lock); 921 922 if (witness_cold) 923 panic("lock (%s) %s destroyed while witness_cold", 924 class->lc_name, lock->lo_name); 925 926 /* XXX: need to verify that no one holds the lock */ 927 if ((lock->lo_flags & LO_WITNESS) == 0 || lock->lo_witness == NULL) 928 return; 929 w = lock->lo_witness; 930 931 mtx_lock_spin(&w_mtx); 932 MPASS(w->w_refcount > 0); 933 w->w_refcount--; 934 935 if (w->w_refcount == 0) 936 depart(w); 937 mtx_unlock_spin(&w_mtx); 938 } 939 940 #ifdef DDB 941 static void 942 witness_ddb_compute_levels(void) 943 { 944 struct witness *w; 945 946 /* 947 * First clear all levels. 948 */ 949 STAILQ_FOREACH(w, &w_all, w_list) 950 w->w_ddb_level = -1; 951 952 /* 953 * Look for locks with no parents and level all their descendants. 954 */ 955 STAILQ_FOREACH(w, &w_all, w_list) { 956 957 /* If the witness has ancestors (is not a root), skip it. */ 958 if (w->w_num_ancestors > 0) 959 continue; 960 witness_ddb_level_descendants(w, 0); 961 } 962 } 963 964 static void 965 witness_ddb_level_descendants(struct witness *w, int l) 966 { 967 int i; 968 969 if (w->w_ddb_level >= l) 970 return; 971 972 w->w_ddb_level = l; 973 l++; 974 975 for (i = 1; i <= w_max_used_index; i++) { 976 if (w_rmatrix[w->w_index][i] & WITNESS_PARENT) 977 witness_ddb_level_descendants(&w_data[i], l); 978 } 979 } 980 981 static void 982 witness_ddb_display_descendants(int(*prnt)(const char *fmt, ...), 983 struct witness *w, int indent) 984 { 985 int i; 986 987 for (i = 0; i < indent; i++) 988 prnt(" "); 989 prnt("%s (type: %s, depth: %d, active refs: %d)", 990 w->w_name, w->w_class->lc_name, 991 w->w_ddb_level, w->w_refcount); 992 if (w->w_displayed) { 993 prnt(" -- (already displayed)\n"); 994 return; 995 } 996 w->w_displayed = 1; 997 if (w->w_file != NULL && w->w_line != 0) 998 prnt(" -- last acquired @ %s:%d\n", fixup_filename(w->w_file), 999 w->w_line); 1000 else 1001 prnt(" -- never acquired\n"); 1002 indent++; 1003 WITNESS_INDEX_ASSERT(w->w_index); 1004 for (i = 1; i <= w_max_used_index; i++) { 1005 if (db_pager_quit) 1006 return; 1007 if (w_rmatrix[w->w_index][i] & WITNESS_PARENT) 1008 witness_ddb_display_descendants(prnt, &w_data[i], 1009 indent); 1010 } 1011 } 1012 1013 static void 1014 witness_ddb_display_list(int(*prnt)(const char *fmt, ...), 1015 struct witness_list *list) 1016 { 1017 struct witness *w; 1018 1019 STAILQ_FOREACH(w, list, w_typelist) { 1020 if (w->w_file == NULL || w->w_ddb_level > 0) 1021 continue; 1022 1023 /* This lock has no anscestors - display its descendants. */ 1024 witness_ddb_display_descendants(prnt, w, 0); 1025 if (db_pager_quit) 1026 return; 1027 } 1028 } 1029 1030 static void 1031 witness_ddb_display(int(*prnt)(const char *fmt, ...)) 1032 { 1033 struct witness *w; 1034 1035 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); 1036 witness_ddb_compute_levels(); 1037 1038 /* Clear all the displayed flags. */ 1039 STAILQ_FOREACH(w, &w_all, w_list) 1040 w->w_displayed = 0; 1041 1042 /* 1043 * First, handle sleep locks which have been acquired at least 1044 * once. 1045 */ 1046 prnt("Sleep locks:\n"); 1047 witness_ddb_display_list(prnt, &w_sleep); 1048 if (db_pager_quit) 1049 return; 1050 1051 /* 1052 * Now do spin locks which have been acquired at least once. 1053 */ 1054 prnt("\nSpin locks:\n"); 1055 witness_ddb_display_list(prnt, &w_spin); 1056 if (db_pager_quit) 1057 return; 1058 1059 /* 1060 * Finally, any locks which have not been acquired yet. 1061 */ 1062 prnt("\nLocks which were never acquired:\n"); 1063 STAILQ_FOREACH(w, &w_all, w_list) { 1064 if (w->w_file != NULL || w->w_refcount == 0) 1065 continue; 1066 prnt("%s (type: %s, depth: %d)\n", w->w_name, 1067 w->w_class->lc_name, w->w_ddb_level); 1068 if (db_pager_quit) 1069 return; 1070 } 1071 } 1072 #endif /* DDB */ 1073 1074 int 1075 witness_defineorder(struct lock_object *lock1, struct lock_object *lock2) 1076 { 1077 1078 if (witness_watch == -1 || panicstr != NULL) 1079 return (0); 1080 1081 /* Require locks that witness knows about. */ 1082 if (lock1 == NULL || lock1->lo_witness == NULL || lock2 == NULL || 1083 lock2->lo_witness == NULL) 1084 return (EINVAL); 1085 1086 mtx_assert(&w_mtx, MA_NOTOWNED); 1087 mtx_lock_spin(&w_mtx); 1088 1089 /* 1090 * If we already have either an explicit or implied lock order that 1091 * is the other way around, then return an error. 1092 */ 1093 if (witness_watch && 1094 isitmydescendant(lock2->lo_witness, lock1->lo_witness)) { 1095 mtx_unlock_spin(&w_mtx); 1096 return (EDOOFUS); 1097 } 1098 1099 /* Try to add the new order. */ 1100 CTR3(KTR_WITNESS, "%s: adding %s as a child of %s", __func__, 1101 lock2->lo_witness->w_name, lock1->lo_witness->w_name); 1102 itismychild(lock1->lo_witness, lock2->lo_witness); 1103 mtx_unlock_spin(&w_mtx); 1104 return (0); 1105 } 1106 1107 void 1108 witness_checkorder(struct lock_object *lock, int flags, const char *file, 1109 int line, struct lock_object *interlock) 1110 { 1111 struct lock_list_entry *lock_list, *lle; 1112 struct lock_instance *lock1, *lock2, *plock; 1113 struct lock_class *class, *iclass; 1114 struct witness *w, *w1; 1115 struct thread *td; 1116 int i, j; 1117 1118 if (witness_cold || witness_watch < 1 || lock->lo_witness == NULL || 1119 panicstr != NULL) 1120 return; 1121 1122 w = lock->lo_witness; 1123 class = LOCK_CLASS(lock); 1124 td = curthread; 1125 1126 if (class->lc_flags & LC_SLEEPLOCK) { 1127 1128 /* 1129 * Since spin locks include a critical section, this check 1130 * implicitly enforces a lock order of all sleep locks before 1131 * all spin locks. 1132 */ 1133 if (td->td_critnest != 0 && !kdb_active) 1134 kassert_panic("acquiring blockable sleep lock with " 1135 "spinlock or critical section held (%s) %s @ %s:%d", 1136 class->lc_name, lock->lo_name, 1137 fixup_filename(file), line); 1138 1139 /* 1140 * If this is the first lock acquired then just return as 1141 * no order checking is needed. 1142 */ 1143 lock_list = td->td_sleeplocks; 1144 if (lock_list == NULL || lock_list->ll_count == 0) 1145 return; 1146 } else { 1147 1148 /* 1149 * If this is the first lock, just return as no order 1150 * checking is needed. Avoid problems with thread 1151 * migration pinning the thread while checking if 1152 * spinlocks are held. If at least one spinlock is held 1153 * the thread is in a safe path and it is allowed to 1154 * unpin it. 1155 */ 1156 sched_pin(); 1157 lock_list = PCPU_GET(spinlocks); 1158 if (lock_list == NULL || lock_list->ll_count == 0) { 1159 sched_unpin(); 1160 return; 1161 } 1162 sched_unpin(); 1163 } 1164 1165 /* 1166 * Check to see if we are recursing on a lock we already own. If 1167 * so, make sure that we don't mismatch exclusive and shared lock 1168 * acquires. 1169 */ 1170 lock1 = find_instance(lock_list, lock); 1171 if (lock1 != NULL) { 1172 if ((lock1->li_flags & LI_EXCLUSIVE) != 0 && 1173 (flags & LOP_EXCLUSIVE) == 0) { 1174 witness_output("shared lock of (%s) %s @ %s:%d\n", 1175 class->lc_name, lock->lo_name, 1176 fixup_filename(file), line); 1177 witness_output("while exclusively locked from %s:%d\n", 1178 fixup_filename(lock1->li_file), lock1->li_line); 1179 kassert_panic("excl->share"); 1180 } 1181 if ((lock1->li_flags & LI_EXCLUSIVE) == 0 && 1182 (flags & LOP_EXCLUSIVE) != 0) { 1183 witness_output("exclusive lock of (%s) %s @ %s:%d\n", 1184 class->lc_name, lock->lo_name, 1185 fixup_filename(file), line); 1186 witness_output("while share locked from %s:%d\n", 1187 fixup_filename(lock1->li_file), lock1->li_line); 1188 kassert_panic("share->excl"); 1189 } 1190 return; 1191 } 1192 1193 /* Warn if the interlock is not locked exactly once. */ 1194 if (interlock != NULL) { 1195 iclass = LOCK_CLASS(interlock); 1196 lock1 = find_instance(lock_list, interlock); 1197 if (lock1 == NULL) 1198 kassert_panic("interlock (%s) %s not locked @ %s:%d", 1199 iclass->lc_name, interlock->lo_name, 1200 fixup_filename(file), line); 1201 else if ((lock1->li_flags & LI_RECURSEMASK) != 0) 1202 kassert_panic("interlock (%s) %s recursed @ %s:%d", 1203 iclass->lc_name, interlock->lo_name, 1204 fixup_filename(file), line); 1205 } 1206 1207 /* 1208 * Find the previously acquired lock, but ignore interlocks. 1209 */ 1210 plock = &lock_list->ll_children[lock_list->ll_count - 1]; 1211 if (interlock != NULL && plock->li_lock == interlock) { 1212 if (lock_list->ll_count > 1) 1213 plock = 1214 &lock_list->ll_children[lock_list->ll_count - 2]; 1215 else { 1216 lle = lock_list->ll_next; 1217 1218 /* 1219 * The interlock is the only lock we hold, so 1220 * simply return. 1221 */ 1222 if (lle == NULL) 1223 return; 1224 plock = &lle->ll_children[lle->ll_count - 1]; 1225 } 1226 } 1227 1228 /* 1229 * Try to perform most checks without a lock. If this succeeds we 1230 * can skip acquiring the lock and return success. Otherwise we redo 1231 * the check with the lock held to handle races with concurrent updates. 1232 */ 1233 w1 = plock->li_lock->lo_witness; 1234 if (witness_lock_order_check(w1, w)) 1235 return; 1236 1237 mtx_lock_spin(&w_mtx); 1238 if (witness_lock_order_check(w1, w)) { 1239 mtx_unlock_spin(&w_mtx); 1240 return; 1241 } 1242 witness_lock_order_add(w1, w); 1243 1244 /* 1245 * Check for duplicate locks of the same type. Note that we only 1246 * have to check for this on the last lock we just acquired. Any 1247 * other cases will be caught as lock order violations. 1248 */ 1249 if (w1 == w) { 1250 i = w->w_index; 1251 if (!(lock->lo_flags & LO_DUPOK) && !(flags & LOP_DUPOK) && 1252 !(w_rmatrix[i][i] & WITNESS_REVERSAL)) { 1253 w_rmatrix[i][i] |= WITNESS_REVERSAL; 1254 w->w_reversed = 1; 1255 mtx_unlock_spin(&w_mtx); 1256 witness_output( 1257 "acquiring duplicate lock of same type: \"%s\"\n", 1258 w->w_name); 1259 witness_output(" 1st %s @ %s:%d\n", plock->li_lock->lo_name, 1260 fixup_filename(plock->li_file), plock->li_line); 1261 witness_output(" 2nd %s @ %s:%d\n", lock->lo_name, 1262 fixup_filename(file), line); 1263 witness_debugger(1, __func__); 1264 } else 1265 mtx_unlock_spin(&w_mtx); 1266 return; 1267 } 1268 mtx_assert(&w_mtx, MA_OWNED); 1269 1270 /* 1271 * If we know that the lock we are acquiring comes after 1272 * the lock we most recently acquired in the lock order tree, 1273 * then there is no need for any further checks. 1274 */ 1275 if (isitmychild(w1, w)) 1276 goto out; 1277 1278 for (j = 0, lle = lock_list; lle != NULL; lle = lle->ll_next) { 1279 for (i = lle->ll_count - 1; i >= 0; i--, j++) { 1280 1281 MPASS(j < LOCK_CHILDCOUNT * LOCK_NCHILDREN); 1282 lock1 = &lle->ll_children[i]; 1283 1284 /* 1285 * Ignore the interlock. 1286 */ 1287 if (interlock == lock1->li_lock) 1288 continue; 1289 1290 /* 1291 * If this lock doesn't undergo witness checking, 1292 * then skip it. 1293 */ 1294 w1 = lock1->li_lock->lo_witness; 1295 if (w1 == NULL) { 1296 KASSERT((lock1->li_lock->lo_flags & LO_WITNESS) == 0, 1297 ("lock missing witness structure")); 1298 continue; 1299 } 1300 1301 /* 1302 * If we are locking Giant and this is a sleepable 1303 * lock, then skip it. 1304 */ 1305 if ((lock1->li_lock->lo_flags & LO_SLEEPABLE) != 0 && 1306 lock == &Giant.lock_object) 1307 continue; 1308 1309 /* 1310 * If we are locking a sleepable lock and this lock 1311 * is Giant, then skip it. 1312 */ 1313 if ((lock->lo_flags & LO_SLEEPABLE) != 0 && 1314 lock1->li_lock == &Giant.lock_object) 1315 continue; 1316 1317 /* 1318 * If we are locking a sleepable lock and this lock 1319 * isn't sleepable, we want to treat it as a lock 1320 * order violation to enfore a general lock order of 1321 * sleepable locks before non-sleepable locks. 1322 */ 1323 if (((lock->lo_flags & LO_SLEEPABLE) != 0 && 1324 (lock1->li_lock->lo_flags & LO_SLEEPABLE) == 0)) 1325 goto reversal; 1326 1327 /* 1328 * If we are locking Giant and this is a non-sleepable 1329 * lock, then treat it as a reversal. 1330 */ 1331 if ((lock1->li_lock->lo_flags & LO_SLEEPABLE) == 0 && 1332 lock == &Giant.lock_object) 1333 goto reversal; 1334 1335 /* 1336 * Check the lock order hierarchy for a reveresal. 1337 */ 1338 if (!isitmydescendant(w, w1)) 1339 continue; 1340 reversal: 1341 1342 /* 1343 * We have a lock order violation, check to see if it 1344 * is allowed or has already been yelled about. 1345 */ 1346 1347 /* Bail if this violation is known */ 1348 if (w_rmatrix[w1->w_index][w->w_index] & WITNESS_REVERSAL) 1349 goto out; 1350 1351 /* Record this as a violation */ 1352 w_rmatrix[w1->w_index][w->w_index] |= WITNESS_REVERSAL; 1353 w_rmatrix[w->w_index][w1->w_index] |= WITNESS_REVERSAL; 1354 w->w_reversed = w1->w_reversed = 1; 1355 witness_increment_graph_generation(); 1356 1357 /* 1358 * If the lock order is blessed, bail before logging 1359 * anything. We don't look for other lock order 1360 * violations though, which may be a bug. 1361 */ 1362 if (blessed(w, w1)) 1363 goto out; 1364 mtx_unlock_spin(&w_mtx); 1365 1366 #ifdef WITNESS_NO_VNODE 1367 /* 1368 * There are known LORs between VNODE locks. They are 1369 * not an indication of a bug. VNODE locks are flagged 1370 * as such (LO_IS_VNODE) and we don't yell if the LOR 1371 * is between 2 VNODE locks. 1372 */ 1373 if ((lock->lo_flags & LO_IS_VNODE) != 0 && 1374 (lock1->li_lock->lo_flags & LO_IS_VNODE) != 0) 1375 return; 1376 #endif 1377 1378 /* 1379 * Ok, yell about it. 1380 */ 1381 if (((lock->lo_flags & LO_SLEEPABLE) != 0 && 1382 (lock1->li_lock->lo_flags & LO_SLEEPABLE) == 0)) 1383 witness_output( 1384 "lock order reversal: (sleepable after non-sleepable)\n"); 1385 else if ((lock1->li_lock->lo_flags & LO_SLEEPABLE) == 0 1386 && lock == &Giant.lock_object) 1387 witness_output( 1388 "lock order reversal: (Giant after non-sleepable)\n"); 1389 else 1390 witness_output("lock order reversal:\n"); 1391 1392 /* 1393 * Try to locate an earlier lock with 1394 * witness w in our list. 1395 */ 1396 do { 1397 lock2 = &lle->ll_children[i]; 1398 MPASS(lock2->li_lock != NULL); 1399 if (lock2->li_lock->lo_witness == w) 1400 break; 1401 if (i == 0 && lle->ll_next != NULL) { 1402 lle = lle->ll_next; 1403 i = lle->ll_count - 1; 1404 MPASS(i >= 0 && i < LOCK_NCHILDREN); 1405 } else 1406 i--; 1407 } while (i >= 0); 1408 if (i < 0) { 1409 witness_output(" 1st %p %s (%s) @ %s:%d\n", 1410 lock1->li_lock, lock1->li_lock->lo_name, 1411 w1->w_name, fixup_filename(lock1->li_file), 1412 lock1->li_line); 1413 witness_output(" 2nd %p %s (%s) @ %s:%d\n", lock, 1414 lock->lo_name, w->w_name, 1415 fixup_filename(file), line); 1416 } else { 1417 witness_output(" 1st %p %s (%s) @ %s:%d\n", 1418 lock2->li_lock, lock2->li_lock->lo_name, 1419 lock2->li_lock->lo_witness->w_name, 1420 fixup_filename(lock2->li_file), 1421 lock2->li_line); 1422 witness_output(" 2nd %p %s (%s) @ %s:%d\n", 1423 lock1->li_lock, lock1->li_lock->lo_name, 1424 w1->w_name, fixup_filename(lock1->li_file), 1425 lock1->li_line); 1426 witness_output(" 3rd %p %s (%s) @ %s:%d\n", lock, 1427 lock->lo_name, w->w_name, 1428 fixup_filename(file), line); 1429 } 1430 witness_debugger(1, __func__); 1431 return; 1432 } 1433 } 1434 1435 /* 1436 * If requested, build a new lock order. However, don't build a new 1437 * relationship between a sleepable lock and Giant if it is in the 1438 * wrong direction. The correct lock order is that sleepable locks 1439 * always come before Giant. 1440 */ 1441 if (flags & LOP_NEWORDER && 1442 !(plock->li_lock == &Giant.lock_object && 1443 (lock->lo_flags & LO_SLEEPABLE) != 0)) { 1444 CTR3(KTR_WITNESS, "%s: adding %s as a child of %s", __func__, 1445 w->w_name, plock->li_lock->lo_witness->w_name); 1446 itismychild(plock->li_lock->lo_witness, w); 1447 } 1448 out: 1449 mtx_unlock_spin(&w_mtx); 1450 } 1451 1452 void 1453 witness_lock(struct lock_object *lock, int flags, const char *file, int line) 1454 { 1455 struct lock_list_entry **lock_list, *lle; 1456 struct lock_instance *instance; 1457 struct witness *w; 1458 struct thread *td; 1459 1460 if (witness_cold || witness_watch == -1 || lock->lo_witness == NULL || 1461 panicstr != NULL) 1462 return; 1463 w = lock->lo_witness; 1464 td = curthread; 1465 1466 /* Determine lock list for this lock. */ 1467 if (LOCK_CLASS(lock)->lc_flags & LC_SLEEPLOCK) 1468 lock_list = &td->td_sleeplocks; 1469 else 1470 lock_list = PCPU_PTR(spinlocks); 1471 1472 /* Check to see if we are recursing on a lock we already own. */ 1473 instance = find_instance(*lock_list, lock); 1474 if (instance != NULL) { 1475 instance->li_flags++; 1476 CTR4(KTR_WITNESS, "%s: pid %d recursed on %s r=%d", __func__, 1477 td->td_proc->p_pid, lock->lo_name, 1478 instance->li_flags & LI_RECURSEMASK); 1479 instance->li_file = file; 1480 instance->li_line = line; 1481 return; 1482 } 1483 1484 /* Update per-witness last file and line acquire. */ 1485 w->w_file = file; 1486 w->w_line = line; 1487 1488 /* Find the next open lock instance in the list and fill it. */ 1489 lle = *lock_list; 1490 if (lle == NULL || lle->ll_count == LOCK_NCHILDREN) { 1491 lle = witness_lock_list_get(); 1492 if (lle == NULL) 1493 return; 1494 lle->ll_next = *lock_list; 1495 CTR3(KTR_WITNESS, "%s: pid %d added lle %p", __func__, 1496 td->td_proc->p_pid, lle); 1497 *lock_list = lle; 1498 } 1499 instance = &lle->ll_children[lle->ll_count++]; 1500 instance->li_lock = lock; 1501 instance->li_line = line; 1502 instance->li_file = file; 1503 if ((flags & LOP_EXCLUSIVE) != 0) 1504 instance->li_flags = LI_EXCLUSIVE; 1505 else 1506 instance->li_flags = 0; 1507 CTR4(KTR_WITNESS, "%s: pid %d added %s as lle[%d]", __func__, 1508 td->td_proc->p_pid, lock->lo_name, lle->ll_count - 1); 1509 } 1510 1511 void 1512 witness_upgrade(struct lock_object *lock, int flags, const char *file, int line) 1513 { 1514 struct lock_instance *instance; 1515 struct lock_class *class; 1516 1517 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); 1518 if (lock->lo_witness == NULL || witness_watch == -1 || panicstr != NULL) 1519 return; 1520 class = LOCK_CLASS(lock); 1521 if (witness_watch) { 1522 if ((lock->lo_flags & LO_UPGRADABLE) == 0) 1523 kassert_panic( 1524 "upgrade of non-upgradable lock (%s) %s @ %s:%d", 1525 class->lc_name, lock->lo_name, 1526 fixup_filename(file), line); 1527 if ((class->lc_flags & LC_SLEEPLOCK) == 0) 1528 kassert_panic( 1529 "upgrade of non-sleep lock (%s) %s @ %s:%d", 1530 class->lc_name, lock->lo_name, 1531 fixup_filename(file), line); 1532 } 1533 instance = find_instance(curthread->td_sleeplocks, lock); 1534 if (instance == NULL) { 1535 kassert_panic("upgrade of unlocked lock (%s) %s @ %s:%d", 1536 class->lc_name, lock->lo_name, 1537 fixup_filename(file), line); 1538 return; 1539 } 1540 if (witness_watch) { 1541 if ((instance->li_flags & LI_EXCLUSIVE) != 0) 1542 kassert_panic( 1543 "upgrade of exclusive lock (%s) %s @ %s:%d", 1544 class->lc_name, lock->lo_name, 1545 fixup_filename(file), line); 1546 if ((instance->li_flags & LI_RECURSEMASK) != 0) 1547 kassert_panic( 1548 "upgrade of recursed lock (%s) %s r=%d @ %s:%d", 1549 class->lc_name, lock->lo_name, 1550 instance->li_flags & LI_RECURSEMASK, 1551 fixup_filename(file), line); 1552 } 1553 instance->li_flags |= LI_EXCLUSIVE; 1554 } 1555 1556 void 1557 witness_downgrade(struct lock_object *lock, int flags, const char *file, 1558 int line) 1559 { 1560 struct lock_instance *instance; 1561 struct lock_class *class; 1562 1563 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); 1564 if (lock->lo_witness == NULL || witness_watch == -1 || panicstr != NULL) 1565 return; 1566 class = LOCK_CLASS(lock); 1567 if (witness_watch) { 1568 if ((lock->lo_flags & LO_UPGRADABLE) == 0) 1569 kassert_panic( 1570 "downgrade of non-upgradable lock (%s) %s @ %s:%d", 1571 class->lc_name, lock->lo_name, 1572 fixup_filename(file), line); 1573 if ((class->lc_flags & LC_SLEEPLOCK) == 0) 1574 kassert_panic( 1575 "downgrade of non-sleep lock (%s) %s @ %s:%d", 1576 class->lc_name, lock->lo_name, 1577 fixup_filename(file), line); 1578 } 1579 instance = find_instance(curthread->td_sleeplocks, lock); 1580 if (instance == NULL) { 1581 kassert_panic("downgrade of unlocked lock (%s) %s @ %s:%d", 1582 class->lc_name, lock->lo_name, 1583 fixup_filename(file), line); 1584 return; 1585 } 1586 if (witness_watch) { 1587 if ((instance->li_flags & LI_EXCLUSIVE) == 0) 1588 kassert_panic( 1589 "downgrade of shared lock (%s) %s @ %s:%d", 1590 class->lc_name, lock->lo_name, 1591 fixup_filename(file), line); 1592 if ((instance->li_flags & LI_RECURSEMASK) != 0) 1593 kassert_panic( 1594 "downgrade of recursed lock (%s) %s r=%d @ %s:%d", 1595 class->lc_name, lock->lo_name, 1596 instance->li_flags & LI_RECURSEMASK, 1597 fixup_filename(file), line); 1598 } 1599 instance->li_flags &= ~LI_EXCLUSIVE; 1600 } 1601 1602 void 1603 witness_unlock(struct lock_object *lock, int flags, const char *file, int line) 1604 { 1605 struct lock_list_entry **lock_list, *lle; 1606 struct lock_instance *instance; 1607 struct lock_class *class; 1608 struct thread *td; 1609 register_t s; 1610 int i, j; 1611 1612 if (witness_cold || lock->lo_witness == NULL || panicstr != NULL) 1613 return; 1614 td = curthread; 1615 class = LOCK_CLASS(lock); 1616 1617 /* Find lock instance associated with this lock. */ 1618 if (class->lc_flags & LC_SLEEPLOCK) 1619 lock_list = &td->td_sleeplocks; 1620 else 1621 lock_list = PCPU_PTR(spinlocks); 1622 lle = *lock_list; 1623 for (; *lock_list != NULL; lock_list = &(*lock_list)->ll_next) 1624 for (i = 0; i < (*lock_list)->ll_count; i++) { 1625 instance = &(*lock_list)->ll_children[i]; 1626 if (instance->li_lock == lock) 1627 goto found; 1628 } 1629 1630 /* 1631 * When disabling WITNESS through witness_watch we could end up in 1632 * having registered locks in the td_sleeplocks queue. 1633 * We have to make sure we flush these queues, so just search for 1634 * eventual register locks and remove them. 1635 */ 1636 if (witness_watch > 0) { 1637 kassert_panic("lock (%s) %s not locked @ %s:%d", class->lc_name, 1638 lock->lo_name, fixup_filename(file), line); 1639 return; 1640 } else { 1641 return; 1642 } 1643 found: 1644 1645 /* First, check for shared/exclusive mismatches. */ 1646 if ((instance->li_flags & LI_EXCLUSIVE) != 0 && witness_watch > 0 && 1647 (flags & LOP_EXCLUSIVE) == 0) { 1648 witness_output("shared unlock of (%s) %s @ %s:%d\n", 1649 class->lc_name, lock->lo_name, fixup_filename(file), line); 1650 witness_output("while exclusively locked from %s:%d\n", 1651 fixup_filename(instance->li_file), instance->li_line); 1652 kassert_panic("excl->ushare"); 1653 } 1654 if ((instance->li_flags & LI_EXCLUSIVE) == 0 && witness_watch > 0 && 1655 (flags & LOP_EXCLUSIVE) != 0) { 1656 witness_output("exclusive unlock of (%s) %s @ %s:%d\n", 1657 class->lc_name, lock->lo_name, fixup_filename(file), line); 1658 witness_output("while share locked from %s:%d\n", 1659 fixup_filename(instance->li_file), 1660 instance->li_line); 1661 kassert_panic("share->uexcl"); 1662 } 1663 /* If we are recursed, unrecurse. */ 1664 if ((instance->li_flags & LI_RECURSEMASK) > 0) { 1665 CTR4(KTR_WITNESS, "%s: pid %d unrecursed on %s r=%d", __func__, 1666 td->td_proc->p_pid, instance->li_lock->lo_name, 1667 instance->li_flags); 1668 instance->li_flags--; 1669 return; 1670 } 1671 /* The lock is now being dropped, check for NORELEASE flag */ 1672 if ((instance->li_flags & LI_NORELEASE) != 0 && witness_watch > 0) { 1673 witness_output("forbidden unlock of (%s) %s @ %s:%d\n", 1674 class->lc_name, lock->lo_name, fixup_filename(file), line); 1675 kassert_panic("lock marked norelease"); 1676 } 1677 1678 /* Otherwise, remove this item from the list. */ 1679 s = intr_disable(); 1680 CTR4(KTR_WITNESS, "%s: pid %d removed %s from lle[%d]", __func__, 1681 td->td_proc->p_pid, instance->li_lock->lo_name, 1682 (*lock_list)->ll_count - 1); 1683 for (j = i; j < (*lock_list)->ll_count - 1; j++) 1684 (*lock_list)->ll_children[j] = 1685 (*lock_list)->ll_children[j + 1]; 1686 (*lock_list)->ll_count--; 1687 intr_restore(s); 1688 1689 /* 1690 * In order to reduce contention on w_mtx, we want to keep always an 1691 * head object into lists so that frequent allocation from the 1692 * free witness pool (and subsequent locking) is avoided. 1693 * In order to maintain the current code simple, when the head 1694 * object is totally unloaded it means also that we do not have 1695 * further objects in the list, so the list ownership needs to be 1696 * hand over to another object if the current head needs to be freed. 1697 */ 1698 if ((*lock_list)->ll_count == 0) { 1699 if (*lock_list == lle) { 1700 if (lle->ll_next == NULL) 1701 return; 1702 } else 1703 lle = *lock_list; 1704 *lock_list = lle->ll_next; 1705 CTR3(KTR_WITNESS, "%s: pid %d removed lle %p", __func__, 1706 td->td_proc->p_pid, lle); 1707 witness_lock_list_free(lle); 1708 } 1709 } 1710 1711 void 1712 witness_thread_exit(struct thread *td) 1713 { 1714 struct lock_list_entry *lle; 1715 int i, n; 1716 1717 lle = td->td_sleeplocks; 1718 if (lle == NULL || panicstr != NULL) 1719 return; 1720 if (lle->ll_count != 0) { 1721 for (n = 0; lle != NULL; lle = lle->ll_next) 1722 for (i = lle->ll_count - 1; i >= 0; i--) { 1723 if (n == 0) 1724 witness_output( 1725 "Thread %p exiting with the following locks held:\n", td); 1726 n++; 1727 witness_list_lock(&lle->ll_children[i], 1728 witness_output); 1729 1730 } 1731 kassert_panic( 1732 "Thread %p cannot exit while holding sleeplocks\n", td); 1733 } 1734 witness_lock_list_free(lle); 1735 } 1736 1737 /* 1738 * Warn if any locks other than 'lock' are held. Flags can be passed in to 1739 * exempt Giant and sleepable locks from the checks as well. If any 1740 * non-exempt locks are held, then a supplied message is printed to the 1741 * output channel along with a list of the offending locks. If indicated in the 1742 * flags then a failure results in a panic as well. 1743 */ 1744 int 1745 witness_warn(int flags, struct lock_object *lock, const char *fmt, ...) 1746 { 1747 struct lock_list_entry *lock_list, *lle; 1748 struct lock_instance *lock1; 1749 struct thread *td; 1750 va_list ap; 1751 int i, n; 1752 1753 if (witness_cold || witness_watch < 1 || panicstr != NULL) 1754 return (0); 1755 n = 0; 1756 td = curthread; 1757 for (lle = td->td_sleeplocks; lle != NULL; lle = lle->ll_next) 1758 for (i = lle->ll_count - 1; i >= 0; i--) { 1759 lock1 = &lle->ll_children[i]; 1760 if (lock1->li_lock == lock) 1761 continue; 1762 if (flags & WARN_GIANTOK && 1763 lock1->li_lock == &Giant.lock_object) 1764 continue; 1765 if (flags & WARN_SLEEPOK && 1766 (lock1->li_lock->lo_flags & LO_SLEEPABLE) != 0) 1767 continue; 1768 if (n == 0) { 1769 va_start(ap, fmt); 1770 vprintf(fmt, ap); 1771 va_end(ap); 1772 printf(" with the following %slocks held:\n", 1773 (flags & WARN_SLEEPOK) != 0 ? 1774 "non-sleepable " : ""); 1775 } 1776 n++; 1777 witness_list_lock(lock1, printf); 1778 } 1779 1780 /* 1781 * Pin the thread in order to avoid problems with thread migration. 1782 * Once that all verifies are passed about spinlocks ownership, 1783 * the thread is in a safe path and it can be unpinned. 1784 */ 1785 sched_pin(); 1786 lock_list = PCPU_GET(spinlocks); 1787 if (lock_list != NULL && lock_list->ll_count != 0) { 1788 sched_unpin(); 1789 1790 /* 1791 * We should only have one spinlock and as long as 1792 * the flags cannot match for this locks class, 1793 * check if the first spinlock is the one curthread 1794 * should hold. 1795 */ 1796 lock1 = &lock_list->ll_children[lock_list->ll_count - 1]; 1797 if (lock_list->ll_count == 1 && lock_list->ll_next == NULL && 1798 lock1->li_lock == lock && n == 0) 1799 return (0); 1800 1801 va_start(ap, fmt); 1802 vprintf(fmt, ap); 1803 va_end(ap); 1804 printf(" with the following %slocks held:\n", 1805 (flags & WARN_SLEEPOK) != 0 ? "non-sleepable " : ""); 1806 n += witness_list_locks(&lock_list, printf); 1807 } else 1808 sched_unpin(); 1809 if (flags & WARN_PANIC && n) 1810 kassert_panic("%s", __func__); 1811 else 1812 witness_debugger(n, __func__); 1813 return (n); 1814 } 1815 1816 const char * 1817 witness_file(struct lock_object *lock) 1818 { 1819 struct witness *w; 1820 1821 if (witness_cold || witness_watch < 1 || lock->lo_witness == NULL) 1822 return ("?"); 1823 w = lock->lo_witness; 1824 return (w->w_file); 1825 } 1826 1827 int 1828 witness_line(struct lock_object *lock) 1829 { 1830 struct witness *w; 1831 1832 if (witness_cold || witness_watch < 1 || lock->lo_witness == NULL) 1833 return (0); 1834 w = lock->lo_witness; 1835 return (w->w_line); 1836 } 1837 1838 static struct witness * 1839 enroll(const char *description, struct lock_class *lock_class) 1840 { 1841 struct witness *w; 1842 1843 MPASS(description != NULL); 1844 1845 if (witness_watch == -1 || panicstr != NULL) 1846 return (NULL); 1847 if ((lock_class->lc_flags & LC_SPINLOCK)) { 1848 if (witness_skipspin) 1849 return (NULL); 1850 } else if ((lock_class->lc_flags & LC_SLEEPLOCK) == 0) { 1851 kassert_panic("lock class %s is not sleep or spin", 1852 lock_class->lc_name); 1853 return (NULL); 1854 } 1855 1856 mtx_lock_spin(&w_mtx); 1857 w = witness_hash_get(description); 1858 if (w) 1859 goto found; 1860 if ((w = witness_get()) == NULL) 1861 return (NULL); 1862 MPASS(strlen(description) < MAX_W_NAME); 1863 strcpy(w->w_name, description); 1864 w->w_class = lock_class; 1865 w->w_refcount = 1; 1866 STAILQ_INSERT_HEAD(&w_all, w, w_list); 1867 if (lock_class->lc_flags & LC_SPINLOCK) { 1868 STAILQ_INSERT_HEAD(&w_spin, w, w_typelist); 1869 w_spin_cnt++; 1870 } else if (lock_class->lc_flags & LC_SLEEPLOCK) { 1871 STAILQ_INSERT_HEAD(&w_sleep, w, w_typelist); 1872 w_sleep_cnt++; 1873 } 1874 1875 /* Insert new witness into the hash */ 1876 witness_hash_put(w); 1877 witness_increment_graph_generation(); 1878 mtx_unlock_spin(&w_mtx); 1879 return (w); 1880 found: 1881 w->w_refcount++; 1882 if (w->w_refcount == 1) 1883 w->w_class = lock_class; 1884 mtx_unlock_spin(&w_mtx); 1885 if (lock_class != w->w_class) 1886 kassert_panic( 1887 "lock (%s) %s does not match earlier (%s) lock", 1888 description, lock_class->lc_name, 1889 w->w_class->lc_name); 1890 return (w); 1891 } 1892 1893 static void 1894 depart(struct witness *w) 1895 { 1896 1897 MPASS(w->w_refcount == 0); 1898 if (w->w_class->lc_flags & LC_SLEEPLOCK) { 1899 w_sleep_cnt--; 1900 } else { 1901 w_spin_cnt--; 1902 } 1903 /* 1904 * Set file to NULL as it may point into a loadable module. 1905 */ 1906 w->w_file = NULL; 1907 w->w_line = 0; 1908 witness_increment_graph_generation(); 1909 } 1910 1911 1912 static void 1913 adopt(struct witness *parent, struct witness *child) 1914 { 1915 int pi, ci, i, j; 1916 1917 if (witness_cold == 0) 1918 mtx_assert(&w_mtx, MA_OWNED); 1919 1920 /* If the relationship is already known, there's no work to be done. */ 1921 if (isitmychild(parent, child)) 1922 return; 1923 1924 /* When the structure of the graph changes, bump up the generation. */ 1925 witness_increment_graph_generation(); 1926 1927 /* 1928 * The hard part ... create the direct relationship, then propagate all 1929 * indirect relationships. 1930 */ 1931 pi = parent->w_index; 1932 ci = child->w_index; 1933 WITNESS_INDEX_ASSERT(pi); 1934 WITNESS_INDEX_ASSERT(ci); 1935 MPASS(pi != ci); 1936 w_rmatrix[pi][ci] |= WITNESS_PARENT; 1937 w_rmatrix[ci][pi] |= WITNESS_CHILD; 1938 1939 /* 1940 * If parent was not already an ancestor of child, 1941 * then we increment the descendant and ancestor counters. 1942 */ 1943 if ((w_rmatrix[pi][ci] & WITNESS_ANCESTOR) == 0) { 1944 parent->w_num_descendants++; 1945 child->w_num_ancestors++; 1946 } 1947 1948 /* 1949 * Find each ancestor of 'pi'. Note that 'pi' itself is counted as 1950 * an ancestor of 'pi' during this loop. 1951 */ 1952 for (i = 1; i <= w_max_used_index; i++) { 1953 if ((w_rmatrix[i][pi] & WITNESS_ANCESTOR_MASK) == 0 && 1954 (i != pi)) 1955 continue; 1956 1957 /* Find each descendant of 'i' and mark it as a descendant. */ 1958 for (j = 1; j <= w_max_used_index; j++) { 1959 1960 /* 1961 * Skip children that are already marked as 1962 * descendants of 'i'. 1963 */ 1964 if (w_rmatrix[i][j] & WITNESS_ANCESTOR_MASK) 1965 continue; 1966 1967 /* 1968 * We are only interested in descendants of 'ci'. Note 1969 * that 'ci' itself is counted as a descendant of 'ci'. 1970 */ 1971 if ((w_rmatrix[ci][j] & WITNESS_ANCESTOR_MASK) == 0 && 1972 (j != ci)) 1973 continue; 1974 w_rmatrix[i][j] |= WITNESS_ANCESTOR; 1975 w_rmatrix[j][i] |= WITNESS_DESCENDANT; 1976 w_data[i].w_num_descendants++; 1977 w_data[j].w_num_ancestors++; 1978 1979 /* 1980 * Make sure we aren't marking a node as both an 1981 * ancestor and descendant. We should have caught 1982 * this as a lock order reversal earlier. 1983 */ 1984 if ((w_rmatrix[i][j] & WITNESS_ANCESTOR_MASK) && 1985 (w_rmatrix[i][j] & WITNESS_DESCENDANT_MASK)) { 1986 printf("witness rmatrix paradox! [%d][%d]=%d " 1987 "both ancestor and descendant\n", 1988 i, j, w_rmatrix[i][j]); 1989 kdb_backtrace(); 1990 printf("Witness disabled.\n"); 1991 witness_watch = -1; 1992 } 1993 if ((w_rmatrix[j][i] & WITNESS_ANCESTOR_MASK) && 1994 (w_rmatrix[j][i] & WITNESS_DESCENDANT_MASK)) { 1995 printf("witness rmatrix paradox! [%d][%d]=%d " 1996 "both ancestor and descendant\n", 1997 j, i, w_rmatrix[j][i]); 1998 kdb_backtrace(); 1999 printf("Witness disabled.\n"); 2000 witness_watch = -1; 2001 } 2002 } 2003 } 2004 } 2005 2006 static void 2007 itismychild(struct witness *parent, struct witness *child) 2008 { 2009 int unlocked; 2010 2011 MPASS(child != NULL && parent != NULL); 2012 if (witness_cold == 0) 2013 mtx_assert(&w_mtx, MA_OWNED); 2014 2015 if (!witness_lock_type_equal(parent, child)) { 2016 if (witness_cold == 0) { 2017 unlocked = 1; 2018 mtx_unlock_spin(&w_mtx); 2019 } else { 2020 unlocked = 0; 2021 } 2022 kassert_panic( 2023 "%s: parent \"%s\" (%s) and child \"%s\" (%s) are not " 2024 "the same lock type", __func__, parent->w_name, 2025 parent->w_class->lc_name, child->w_name, 2026 child->w_class->lc_name); 2027 if (unlocked) 2028 mtx_lock_spin(&w_mtx); 2029 } 2030 adopt(parent, child); 2031 } 2032 2033 /* 2034 * Generic code for the isitmy*() functions. The rmask parameter is the 2035 * expected relationship of w1 to w2. 2036 */ 2037 static int 2038 _isitmyx(struct witness *w1, struct witness *w2, int rmask, const char *fname) 2039 { 2040 unsigned char r1, r2; 2041 int i1, i2; 2042 2043 i1 = w1->w_index; 2044 i2 = w2->w_index; 2045 WITNESS_INDEX_ASSERT(i1); 2046 WITNESS_INDEX_ASSERT(i2); 2047 r1 = w_rmatrix[i1][i2] & WITNESS_RELATED_MASK; 2048 r2 = w_rmatrix[i2][i1] & WITNESS_RELATED_MASK; 2049 2050 /* The flags on one better be the inverse of the flags on the other */ 2051 if (!((WITNESS_ATOD(r1) == r2 && WITNESS_DTOA(r2) == r1) || 2052 (WITNESS_DTOA(r1) == r2 && WITNESS_ATOD(r2) == r1))) { 2053 /* Don't squawk if we're potentially racing with an update. */ 2054 if (!mtx_owned(&w_mtx)) 2055 return (0); 2056 printf("%s: rmatrix mismatch between %s (index %d) and %s " 2057 "(index %d): w_rmatrix[%d][%d] == %hhx but " 2058 "w_rmatrix[%d][%d] == %hhx\n", 2059 fname, w1->w_name, i1, w2->w_name, i2, i1, i2, r1, 2060 i2, i1, r2); 2061 kdb_backtrace(); 2062 printf("Witness disabled.\n"); 2063 witness_watch = -1; 2064 } 2065 return (r1 & rmask); 2066 } 2067 2068 /* 2069 * Checks if @child is a direct child of @parent. 2070 */ 2071 static int 2072 isitmychild(struct witness *parent, struct witness *child) 2073 { 2074 2075 return (_isitmyx(parent, child, WITNESS_PARENT, __func__)); 2076 } 2077 2078 /* 2079 * Checks if @descendant is a direct or inderect descendant of @ancestor. 2080 */ 2081 static int 2082 isitmydescendant(struct witness *ancestor, struct witness *descendant) 2083 { 2084 2085 return (_isitmyx(ancestor, descendant, WITNESS_ANCESTOR_MASK, 2086 __func__)); 2087 } 2088 2089 static int 2090 blessed(struct witness *w1, struct witness *w2) 2091 { 2092 int i; 2093 struct witness_blessed *b; 2094 2095 for (i = 0; i < nitems(blessed_list); i++) { 2096 b = &blessed_list[i]; 2097 if (strcmp(w1->w_name, b->b_lock1) == 0) { 2098 if (strcmp(w2->w_name, b->b_lock2) == 0) 2099 return (1); 2100 continue; 2101 } 2102 if (strcmp(w1->w_name, b->b_lock2) == 0) 2103 if (strcmp(w2->w_name, b->b_lock1) == 0) 2104 return (1); 2105 } 2106 return (0); 2107 } 2108 2109 static struct witness * 2110 witness_get(void) 2111 { 2112 struct witness *w; 2113 int index; 2114 2115 if (witness_cold == 0) 2116 mtx_assert(&w_mtx, MA_OWNED); 2117 2118 if (witness_watch == -1) { 2119 mtx_unlock_spin(&w_mtx); 2120 return (NULL); 2121 } 2122 if (STAILQ_EMPTY(&w_free)) { 2123 witness_watch = -1; 2124 mtx_unlock_spin(&w_mtx); 2125 printf("WITNESS: unable to allocate a new witness object\n"); 2126 return (NULL); 2127 } 2128 w = STAILQ_FIRST(&w_free); 2129 STAILQ_REMOVE_HEAD(&w_free, w_list); 2130 w_free_cnt--; 2131 index = w->w_index; 2132 MPASS(index > 0 && index == w_max_used_index+1 && 2133 index < witness_count); 2134 bzero(w, sizeof(*w)); 2135 w->w_index = index; 2136 if (index > w_max_used_index) 2137 w_max_used_index = index; 2138 return (w); 2139 } 2140 2141 static void 2142 witness_free(struct witness *w) 2143 { 2144 2145 STAILQ_INSERT_HEAD(&w_free, w, w_list); 2146 w_free_cnt++; 2147 } 2148 2149 static struct lock_list_entry * 2150 witness_lock_list_get(void) 2151 { 2152 struct lock_list_entry *lle; 2153 2154 if (witness_watch == -1) 2155 return (NULL); 2156 mtx_lock_spin(&w_mtx); 2157 lle = w_lock_list_free; 2158 if (lle == NULL) { 2159 witness_watch = -1; 2160 mtx_unlock_spin(&w_mtx); 2161 printf("%s: witness exhausted\n", __func__); 2162 return (NULL); 2163 } 2164 w_lock_list_free = lle->ll_next; 2165 mtx_unlock_spin(&w_mtx); 2166 bzero(lle, sizeof(*lle)); 2167 return (lle); 2168 } 2169 2170 static void 2171 witness_lock_list_free(struct lock_list_entry *lle) 2172 { 2173 2174 mtx_lock_spin(&w_mtx); 2175 lle->ll_next = w_lock_list_free; 2176 w_lock_list_free = lle; 2177 mtx_unlock_spin(&w_mtx); 2178 } 2179 2180 static struct lock_instance * 2181 find_instance(struct lock_list_entry *list, const struct lock_object *lock) 2182 { 2183 struct lock_list_entry *lle; 2184 struct lock_instance *instance; 2185 int i; 2186 2187 for (lle = list; lle != NULL; lle = lle->ll_next) 2188 for (i = lle->ll_count - 1; i >= 0; i--) { 2189 instance = &lle->ll_children[i]; 2190 if (instance->li_lock == lock) 2191 return (instance); 2192 } 2193 return (NULL); 2194 } 2195 2196 static void 2197 witness_list_lock(struct lock_instance *instance, 2198 int (*prnt)(const char *fmt, ...)) 2199 { 2200 struct lock_object *lock; 2201 2202 lock = instance->li_lock; 2203 prnt("%s %s %s", (instance->li_flags & LI_EXCLUSIVE) != 0 ? 2204 "exclusive" : "shared", LOCK_CLASS(lock)->lc_name, lock->lo_name); 2205 if (lock->lo_witness->w_name != lock->lo_name) 2206 prnt(" (%s)", lock->lo_witness->w_name); 2207 prnt(" r = %d (%p) locked @ %s:%d\n", 2208 instance->li_flags & LI_RECURSEMASK, lock, 2209 fixup_filename(instance->li_file), instance->li_line); 2210 } 2211 2212 static int 2213 witness_output(const char *fmt, ...) 2214 { 2215 va_list ap; 2216 int ret; 2217 2218 va_start(ap, fmt); 2219 ret = witness_voutput(fmt, ap); 2220 va_end(ap); 2221 return (ret); 2222 } 2223 2224 static int 2225 witness_voutput(const char *fmt, va_list ap) 2226 { 2227 int ret; 2228 2229 ret = 0; 2230 switch (witness_channel) { 2231 case WITNESS_CONSOLE: 2232 ret = vprintf(fmt, ap); 2233 break; 2234 case WITNESS_LOG: 2235 vlog(LOG_NOTICE, fmt, ap); 2236 break; 2237 case WITNESS_NONE: 2238 break; 2239 } 2240 return (ret); 2241 } 2242 2243 #ifdef DDB 2244 static int 2245 witness_thread_has_locks(struct thread *td) 2246 { 2247 2248 if (td->td_sleeplocks == NULL) 2249 return (0); 2250 return (td->td_sleeplocks->ll_count != 0); 2251 } 2252 2253 static int 2254 witness_proc_has_locks(struct proc *p) 2255 { 2256 struct thread *td; 2257 2258 FOREACH_THREAD_IN_PROC(p, td) { 2259 if (witness_thread_has_locks(td)) 2260 return (1); 2261 } 2262 return (0); 2263 } 2264 #endif 2265 2266 int 2267 witness_list_locks(struct lock_list_entry **lock_list, 2268 int (*prnt)(const char *fmt, ...)) 2269 { 2270 struct lock_list_entry *lle; 2271 int i, nheld; 2272 2273 nheld = 0; 2274 for (lle = *lock_list; lle != NULL; lle = lle->ll_next) 2275 for (i = lle->ll_count - 1; i >= 0; i--) { 2276 witness_list_lock(&lle->ll_children[i], prnt); 2277 nheld++; 2278 } 2279 return (nheld); 2280 } 2281 2282 /* 2283 * This is a bit risky at best. We call this function when we have timed 2284 * out acquiring a spin lock, and we assume that the other CPU is stuck 2285 * with this lock held. So, we go groveling around in the other CPU's 2286 * per-cpu data to try to find the lock instance for this spin lock to 2287 * see when it was last acquired. 2288 */ 2289 void 2290 witness_display_spinlock(struct lock_object *lock, struct thread *owner, 2291 int (*prnt)(const char *fmt, ...)) 2292 { 2293 struct lock_instance *instance; 2294 struct pcpu *pc; 2295 2296 if (owner->td_critnest == 0 || owner->td_oncpu == NOCPU) 2297 return; 2298 pc = pcpu_find(owner->td_oncpu); 2299 instance = find_instance(pc->pc_spinlocks, lock); 2300 if (instance != NULL) 2301 witness_list_lock(instance, prnt); 2302 } 2303 2304 void 2305 witness_save(struct lock_object *lock, const char **filep, int *linep) 2306 { 2307 struct lock_list_entry *lock_list; 2308 struct lock_instance *instance; 2309 struct lock_class *class; 2310 2311 /* 2312 * This function is used independently in locking code to deal with 2313 * Giant, SCHEDULER_STOPPED() check can be removed here after Giant 2314 * is gone. 2315 */ 2316 if (SCHEDULER_STOPPED()) 2317 return; 2318 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); 2319 if (lock->lo_witness == NULL || witness_watch == -1 || panicstr != NULL) 2320 return; 2321 class = LOCK_CLASS(lock); 2322 if (class->lc_flags & LC_SLEEPLOCK) 2323 lock_list = curthread->td_sleeplocks; 2324 else { 2325 if (witness_skipspin) 2326 return; 2327 lock_list = PCPU_GET(spinlocks); 2328 } 2329 instance = find_instance(lock_list, lock); 2330 if (instance == NULL) { 2331 kassert_panic("%s: lock (%s) %s not locked", __func__, 2332 class->lc_name, lock->lo_name); 2333 return; 2334 } 2335 *filep = instance->li_file; 2336 *linep = instance->li_line; 2337 } 2338 2339 void 2340 witness_restore(struct lock_object *lock, const char *file, int line) 2341 { 2342 struct lock_list_entry *lock_list; 2343 struct lock_instance *instance; 2344 struct lock_class *class; 2345 2346 /* 2347 * This function is used independently in locking code to deal with 2348 * Giant, SCHEDULER_STOPPED() check can be removed here after Giant 2349 * is gone. 2350 */ 2351 if (SCHEDULER_STOPPED()) 2352 return; 2353 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); 2354 if (lock->lo_witness == NULL || witness_watch == -1 || panicstr != NULL) 2355 return; 2356 class = LOCK_CLASS(lock); 2357 if (class->lc_flags & LC_SLEEPLOCK) 2358 lock_list = curthread->td_sleeplocks; 2359 else { 2360 if (witness_skipspin) 2361 return; 2362 lock_list = PCPU_GET(spinlocks); 2363 } 2364 instance = find_instance(lock_list, lock); 2365 if (instance == NULL) 2366 kassert_panic("%s: lock (%s) %s not locked", __func__, 2367 class->lc_name, lock->lo_name); 2368 lock->lo_witness->w_file = file; 2369 lock->lo_witness->w_line = line; 2370 if (instance == NULL) 2371 return; 2372 instance->li_file = file; 2373 instance->li_line = line; 2374 } 2375 2376 void 2377 witness_assert(const struct lock_object *lock, int flags, const char *file, 2378 int line) 2379 { 2380 #ifdef INVARIANT_SUPPORT 2381 struct lock_instance *instance; 2382 struct lock_class *class; 2383 2384 if (lock->lo_witness == NULL || witness_watch < 1 || panicstr != NULL) 2385 return; 2386 class = LOCK_CLASS(lock); 2387 if ((class->lc_flags & LC_SLEEPLOCK) != 0) 2388 instance = find_instance(curthread->td_sleeplocks, lock); 2389 else if ((class->lc_flags & LC_SPINLOCK) != 0) 2390 instance = find_instance(PCPU_GET(spinlocks), lock); 2391 else { 2392 kassert_panic("Lock (%s) %s is not sleep or spin!", 2393 class->lc_name, lock->lo_name); 2394 return; 2395 } 2396 switch (flags) { 2397 case LA_UNLOCKED: 2398 if (instance != NULL) 2399 kassert_panic("Lock (%s) %s locked @ %s:%d.", 2400 class->lc_name, lock->lo_name, 2401 fixup_filename(file), line); 2402 break; 2403 case LA_LOCKED: 2404 case LA_LOCKED | LA_RECURSED: 2405 case LA_LOCKED | LA_NOTRECURSED: 2406 case LA_SLOCKED: 2407 case LA_SLOCKED | LA_RECURSED: 2408 case LA_SLOCKED | LA_NOTRECURSED: 2409 case LA_XLOCKED: 2410 case LA_XLOCKED | LA_RECURSED: 2411 case LA_XLOCKED | LA_NOTRECURSED: 2412 if (instance == NULL) { 2413 kassert_panic("Lock (%s) %s not locked @ %s:%d.", 2414 class->lc_name, lock->lo_name, 2415 fixup_filename(file), line); 2416 break; 2417 } 2418 if ((flags & LA_XLOCKED) != 0 && 2419 (instance->li_flags & LI_EXCLUSIVE) == 0) 2420 kassert_panic( 2421 "Lock (%s) %s not exclusively locked @ %s:%d.", 2422 class->lc_name, lock->lo_name, 2423 fixup_filename(file), line); 2424 if ((flags & LA_SLOCKED) != 0 && 2425 (instance->li_flags & LI_EXCLUSIVE) != 0) 2426 kassert_panic( 2427 "Lock (%s) %s exclusively locked @ %s:%d.", 2428 class->lc_name, lock->lo_name, 2429 fixup_filename(file), line); 2430 if ((flags & LA_RECURSED) != 0 && 2431 (instance->li_flags & LI_RECURSEMASK) == 0) 2432 kassert_panic("Lock (%s) %s not recursed @ %s:%d.", 2433 class->lc_name, lock->lo_name, 2434 fixup_filename(file), line); 2435 if ((flags & LA_NOTRECURSED) != 0 && 2436 (instance->li_flags & LI_RECURSEMASK) != 0) 2437 kassert_panic("Lock (%s) %s recursed @ %s:%d.", 2438 class->lc_name, lock->lo_name, 2439 fixup_filename(file), line); 2440 break; 2441 default: 2442 kassert_panic("Invalid lock assertion at %s:%d.", 2443 fixup_filename(file), line); 2444 2445 } 2446 #endif /* INVARIANT_SUPPORT */ 2447 } 2448 2449 static void 2450 witness_setflag(struct lock_object *lock, int flag, int set) 2451 { 2452 struct lock_list_entry *lock_list; 2453 struct lock_instance *instance; 2454 struct lock_class *class; 2455 2456 if (lock->lo_witness == NULL || witness_watch == -1 || panicstr != NULL) 2457 return; 2458 class = LOCK_CLASS(lock); 2459 if (class->lc_flags & LC_SLEEPLOCK) 2460 lock_list = curthread->td_sleeplocks; 2461 else { 2462 if (witness_skipspin) 2463 return; 2464 lock_list = PCPU_GET(spinlocks); 2465 } 2466 instance = find_instance(lock_list, lock); 2467 if (instance == NULL) { 2468 kassert_panic("%s: lock (%s) %s not locked", __func__, 2469 class->lc_name, lock->lo_name); 2470 return; 2471 } 2472 2473 if (set) 2474 instance->li_flags |= flag; 2475 else 2476 instance->li_flags &= ~flag; 2477 } 2478 2479 void 2480 witness_norelease(struct lock_object *lock) 2481 { 2482 2483 witness_setflag(lock, LI_NORELEASE, 1); 2484 } 2485 2486 void 2487 witness_releaseok(struct lock_object *lock) 2488 { 2489 2490 witness_setflag(lock, LI_NORELEASE, 0); 2491 } 2492 2493 #ifdef DDB 2494 static void 2495 witness_ddb_list(struct thread *td) 2496 { 2497 2498 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); 2499 KASSERT(kdb_active, ("%s: not in the debugger", __func__)); 2500 2501 if (witness_watch < 1) 2502 return; 2503 2504 witness_list_locks(&td->td_sleeplocks, db_printf); 2505 2506 /* 2507 * We only handle spinlocks if td == curthread. This is somewhat broken 2508 * if td is currently executing on some other CPU and holds spin locks 2509 * as we won't display those locks. If we had a MI way of getting 2510 * the per-cpu data for a given cpu then we could use 2511 * td->td_oncpu to get the list of spinlocks for this thread 2512 * and "fix" this. 2513 * 2514 * That still wouldn't really fix this unless we locked the scheduler 2515 * lock or stopped the other CPU to make sure it wasn't changing the 2516 * list out from under us. It is probably best to just not try to 2517 * handle threads on other CPU's for now. 2518 */ 2519 if (td == curthread && PCPU_GET(spinlocks) != NULL) 2520 witness_list_locks(PCPU_PTR(spinlocks), db_printf); 2521 } 2522 2523 DB_SHOW_COMMAND(locks, db_witness_list) 2524 { 2525 struct thread *td; 2526 2527 if (have_addr) 2528 td = db_lookup_thread(addr, true); 2529 else 2530 td = kdb_thread; 2531 witness_ddb_list(td); 2532 } 2533 2534 DB_SHOW_ALL_COMMAND(locks, db_witness_list_all) 2535 { 2536 struct thread *td; 2537 struct proc *p; 2538 2539 /* 2540 * It would be nice to list only threads and processes that actually 2541 * held sleep locks, but that information is currently not exported 2542 * by WITNESS. 2543 */ 2544 FOREACH_PROC_IN_SYSTEM(p) { 2545 if (!witness_proc_has_locks(p)) 2546 continue; 2547 FOREACH_THREAD_IN_PROC(p, td) { 2548 if (!witness_thread_has_locks(td)) 2549 continue; 2550 db_printf("Process %d (%s) thread %p (%d)\n", p->p_pid, 2551 p->p_comm, td, td->td_tid); 2552 witness_ddb_list(td); 2553 if (db_pager_quit) 2554 return; 2555 } 2556 } 2557 } 2558 DB_SHOW_ALIAS(alllocks, db_witness_list_all) 2559 2560 DB_SHOW_COMMAND(witness, db_witness_display) 2561 { 2562 2563 witness_ddb_display(db_printf); 2564 } 2565 #endif 2566 2567 static void 2568 sbuf_print_witness_badstacks(struct sbuf *sb, size_t *oldidx) 2569 { 2570 struct witness_lock_order_data *data1, *data2, *tmp_data1, *tmp_data2; 2571 struct witness *tmp_w1, *tmp_w2, *w1, *w2; 2572 int generation, i, j; 2573 2574 tmp_data1 = NULL; 2575 tmp_data2 = NULL; 2576 tmp_w1 = NULL; 2577 tmp_w2 = NULL; 2578 2579 /* Allocate and init temporary storage space. */ 2580 tmp_w1 = malloc(sizeof(struct witness), M_TEMP, M_WAITOK | M_ZERO); 2581 tmp_w2 = malloc(sizeof(struct witness), M_TEMP, M_WAITOK | M_ZERO); 2582 tmp_data1 = malloc(sizeof(struct witness_lock_order_data), M_TEMP, 2583 M_WAITOK | M_ZERO); 2584 tmp_data2 = malloc(sizeof(struct witness_lock_order_data), M_TEMP, 2585 M_WAITOK | M_ZERO); 2586 stack_zero(&tmp_data1->wlod_stack); 2587 stack_zero(&tmp_data2->wlod_stack); 2588 2589 restart: 2590 mtx_lock_spin(&w_mtx); 2591 generation = w_generation; 2592 mtx_unlock_spin(&w_mtx); 2593 sbuf_printf(sb, "Number of known direct relationships is %d\n", 2594 w_lohash.wloh_count); 2595 for (i = 1; i < w_max_used_index; i++) { 2596 mtx_lock_spin(&w_mtx); 2597 if (generation != w_generation) { 2598 mtx_unlock_spin(&w_mtx); 2599 2600 /* The graph has changed, try again. */ 2601 *oldidx = 0; 2602 sbuf_clear(sb); 2603 goto restart; 2604 } 2605 2606 w1 = &w_data[i]; 2607 if (w1->w_reversed == 0) { 2608 mtx_unlock_spin(&w_mtx); 2609 continue; 2610 } 2611 2612 /* Copy w1 locally so we can release the spin lock. */ 2613 *tmp_w1 = *w1; 2614 mtx_unlock_spin(&w_mtx); 2615 2616 if (tmp_w1->w_reversed == 0) 2617 continue; 2618 for (j = 1; j < w_max_used_index; j++) { 2619 if ((w_rmatrix[i][j] & WITNESS_REVERSAL) == 0 || i > j) 2620 continue; 2621 2622 mtx_lock_spin(&w_mtx); 2623 if (generation != w_generation) { 2624 mtx_unlock_spin(&w_mtx); 2625 2626 /* The graph has changed, try again. */ 2627 *oldidx = 0; 2628 sbuf_clear(sb); 2629 goto restart; 2630 } 2631 2632 w2 = &w_data[j]; 2633 data1 = witness_lock_order_get(w1, w2); 2634 data2 = witness_lock_order_get(w2, w1); 2635 2636 /* 2637 * Copy information locally so we can release the 2638 * spin lock. 2639 */ 2640 *tmp_w2 = *w2; 2641 2642 if (data1) { 2643 stack_zero(&tmp_data1->wlod_stack); 2644 stack_copy(&data1->wlod_stack, 2645 &tmp_data1->wlod_stack); 2646 } 2647 if (data2 && data2 != data1) { 2648 stack_zero(&tmp_data2->wlod_stack); 2649 stack_copy(&data2->wlod_stack, 2650 &tmp_data2->wlod_stack); 2651 } 2652 mtx_unlock_spin(&w_mtx); 2653 2654 if (blessed(tmp_w1, tmp_w2)) 2655 continue; 2656 2657 sbuf_printf(sb, 2658 "\nLock order reversal between \"%s\"(%s) and \"%s\"(%s)!\n", 2659 tmp_w1->w_name, tmp_w1->w_class->lc_name, 2660 tmp_w2->w_name, tmp_w2->w_class->lc_name); 2661 if (data1) { 2662 sbuf_printf(sb, 2663 "Lock order \"%s\"(%s) -> \"%s\"(%s) first seen at:\n", 2664 tmp_w1->w_name, tmp_w1->w_class->lc_name, 2665 tmp_w2->w_name, tmp_w2->w_class->lc_name); 2666 stack_sbuf_print(sb, &tmp_data1->wlod_stack); 2667 sbuf_printf(sb, "\n"); 2668 } 2669 if (data2 && data2 != data1) { 2670 sbuf_printf(sb, 2671 "Lock order \"%s\"(%s) -> \"%s\"(%s) first seen at:\n", 2672 tmp_w2->w_name, tmp_w2->w_class->lc_name, 2673 tmp_w1->w_name, tmp_w1->w_class->lc_name); 2674 stack_sbuf_print(sb, &tmp_data2->wlod_stack); 2675 sbuf_printf(sb, "\n"); 2676 } 2677 } 2678 } 2679 mtx_lock_spin(&w_mtx); 2680 if (generation != w_generation) { 2681 mtx_unlock_spin(&w_mtx); 2682 2683 /* 2684 * The graph changed while we were printing stack data, 2685 * try again. 2686 */ 2687 *oldidx = 0; 2688 sbuf_clear(sb); 2689 goto restart; 2690 } 2691 mtx_unlock_spin(&w_mtx); 2692 2693 /* Free temporary storage space. */ 2694 free(tmp_data1, M_TEMP); 2695 free(tmp_data2, M_TEMP); 2696 free(tmp_w1, M_TEMP); 2697 free(tmp_w2, M_TEMP); 2698 } 2699 2700 static int 2701 sysctl_debug_witness_badstacks(SYSCTL_HANDLER_ARGS) 2702 { 2703 struct sbuf *sb; 2704 int error; 2705 2706 if (witness_watch < 1) { 2707 error = SYSCTL_OUT(req, w_notrunning, sizeof(w_notrunning)); 2708 return (error); 2709 } 2710 if (witness_cold) { 2711 error = SYSCTL_OUT(req, w_stillcold, sizeof(w_stillcold)); 2712 return (error); 2713 } 2714 error = 0; 2715 sb = sbuf_new(NULL, NULL, badstack_sbuf_size, SBUF_AUTOEXTEND); 2716 if (sb == NULL) 2717 return (ENOMEM); 2718 2719 sbuf_print_witness_badstacks(sb, &req->oldidx); 2720 2721 sbuf_finish(sb); 2722 error = SYSCTL_OUT(req, sbuf_data(sb), sbuf_len(sb) + 1); 2723 sbuf_delete(sb); 2724 2725 return (error); 2726 } 2727 2728 #ifdef DDB 2729 static int 2730 sbuf_db_printf_drain(void *arg __unused, const char *data, int len) 2731 { 2732 2733 return (db_printf("%.*s", len, data)); 2734 } 2735 2736 DB_SHOW_COMMAND(badstacks, db_witness_badstacks) 2737 { 2738 struct sbuf sb; 2739 char buffer[128]; 2740 size_t dummy; 2741 2742 sbuf_new(&sb, buffer, sizeof(buffer), SBUF_FIXEDLEN); 2743 sbuf_set_drain(&sb, sbuf_db_printf_drain, NULL); 2744 sbuf_print_witness_badstacks(&sb, &dummy); 2745 sbuf_finish(&sb); 2746 } 2747 #endif 2748 2749 static int 2750 sysctl_debug_witness_channel(SYSCTL_HANDLER_ARGS) 2751 { 2752 static const struct { 2753 enum witness_channel channel; 2754 const char *name; 2755 } channels[] = { 2756 { WITNESS_CONSOLE, "console" }, 2757 { WITNESS_LOG, "log" }, 2758 { WITNESS_NONE, "none" }, 2759 }; 2760 char buf[16]; 2761 u_int i; 2762 int error; 2763 2764 buf[0] = '\0'; 2765 for (i = 0; i < nitems(channels); i++) 2766 if (witness_channel == channels[i].channel) { 2767 snprintf(buf, sizeof(buf), "%s", channels[i].name); 2768 break; 2769 } 2770 2771 error = sysctl_handle_string(oidp, buf, sizeof(buf), req); 2772 if (error != 0 || req->newptr == NULL) 2773 return (error); 2774 2775 error = EINVAL; 2776 for (i = 0; i < nitems(channels); i++) 2777 if (strcmp(channels[i].name, buf) == 0) { 2778 witness_channel = channels[i].channel; 2779 error = 0; 2780 break; 2781 } 2782 return (error); 2783 } 2784 2785 static int 2786 sysctl_debug_witness_fullgraph(SYSCTL_HANDLER_ARGS) 2787 { 2788 struct witness *w; 2789 struct sbuf *sb; 2790 int error; 2791 2792 #ifdef __i386__ 2793 error = SYSCTL_OUT(req, w_notallowed, sizeof(w_notallowed)); 2794 return (error); 2795 #endif 2796 2797 if (witness_watch < 1) { 2798 error = SYSCTL_OUT(req, w_notrunning, sizeof(w_notrunning)); 2799 return (error); 2800 } 2801 if (witness_cold) { 2802 error = SYSCTL_OUT(req, w_stillcold, sizeof(w_stillcold)); 2803 return (error); 2804 } 2805 error = 0; 2806 2807 error = sysctl_wire_old_buffer(req, 0); 2808 if (error != 0) 2809 return (error); 2810 sb = sbuf_new_for_sysctl(NULL, NULL, FULLGRAPH_SBUF_SIZE, req); 2811 if (sb == NULL) 2812 return (ENOMEM); 2813 sbuf_printf(sb, "\n"); 2814 2815 mtx_lock_spin(&w_mtx); 2816 STAILQ_FOREACH(w, &w_all, w_list) 2817 w->w_displayed = 0; 2818 STAILQ_FOREACH(w, &w_all, w_list) 2819 witness_add_fullgraph(sb, w); 2820 mtx_unlock_spin(&w_mtx); 2821 2822 /* 2823 * Close the sbuf and return to userland. 2824 */ 2825 error = sbuf_finish(sb); 2826 sbuf_delete(sb); 2827 2828 return (error); 2829 } 2830 2831 static int 2832 sysctl_debug_witness_watch(SYSCTL_HANDLER_ARGS) 2833 { 2834 int error, value; 2835 2836 value = witness_watch; 2837 error = sysctl_handle_int(oidp, &value, 0, req); 2838 if (error != 0 || req->newptr == NULL) 2839 return (error); 2840 if (value > 1 || value < -1 || 2841 (witness_watch == -1 && value != witness_watch)) 2842 return (EINVAL); 2843 witness_watch = value; 2844 return (0); 2845 } 2846 2847 static void 2848 witness_add_fullgraph(struct sbuf *sb, struct witness *w) 2849 { 2850 int i; 2851 2852 if (w->w_displayed != 0 || (w->w_file == NULL && w->w_line == 0)) 2853 return; 2854 w->w_displayed = 1; 2855 2856 WITNESS_INDEX_ASSERT(w->w_index); 2857 for (i = 1; i <= w_max_used_index; i++) { 2858 if (w_rmatrix[w->w_index][i] & WITNESS_PARENT) { 2859 sbuf_printf(sb, "\"%s\",\"%s\"\n", w->w_name, 2860 w_data[i].w_name); 2861 witness_add_fullgraph(sb, &w_data[i]); 2862 } 2863 } 2864 } 2865 2866 /* 2867 * A simple hash function. Takes a key pointer and a key size. If size == 0, 2868 * interprets the key as a string and reads until the null 2869 * terminator. Otherwise, reads the first size bytes. Returns an unsigned 32-bit 2870 * hash value computed from the key. 2871 */ 2872 static uint32_t 2873 witness_hash_djb2(const uint8_t *key, uint32_t size) 2874 { 2875 unsigned int hash = 5381; 2876 int i; 2877 2878 /* hash = hash * 33 + key[i] */ 2879 if (size) 2880 for (i = 0; i < size; i++) 2881 hash = ((hash << 5) + hash) + (unsigned int)key[i]; 2882 else 2883 for (i = 0; key[i] != 0; i++) 2884 hash = ((hash << 5) + hash) + (unsigned int)key[i]; 2885 2886 return (hash); 2887 } 2888 2889 2890 /* 2891 * Initializes the two witness hash tables. Called exactly once from 2892 * witness_initialize(). 2893 */ 2894 static void 2895 witness_init_hash_tables(void) 2896 { 2897 int i; 2898 2899 MPASS(witness_cold); 2900 2901 /* Initialize the hash tables. */ 2902 for (i = 0; i < WITNESS_HASH_SIZE; i++) 2903 w_hash.wh_array[i] = NULL; 2904 2905 w_hash.wh_size = WITNESS_HASH_SIZE; 2906 w_hash.wh_count = 0; 2907 2908 /* Initialize the lock order data hash. */ 2909 w_lofree = NULL; 2910 for (i = 0; i < WITNESS_LO_DATA_COUNT; i++) { 2911 memset(&w_lodata[i], 0, sizeof(w_lodata[i])); 2912 w_lodata[i].wlod_next = w_lofree; 2913 w_lofree = &w_lodata[i]; 2914 } 2915 w_lohash.wloh_size = WITNESS_LO_HASH_SIZE; 2916 w_lohash.wloh_count = 0; 2917 for (i = 0; i < WITNESS_LO_HASH_SIZE; i++) 2918 w_lohash.wloh_array[i] = NULL; 2919 } 2920 2921 static struct witness * 2922 witness_hash_get(const char *key) 2923 { 2924 struct witness *w; 2925 uint32_t hash; 2926 2927 MPASS(key != NULL); 2928 if (witness_cold == 0) 2929 mtx_assert(&w_mtx, MA_OWNED); 2930 hash = witness_hash_djb2(key, 0) % w_hash.wh_size; 2931 w = w_hash.wh_array[hash]; 2932 while (w != NULL) { 2933 if (strcmp(w->w_name, key) == 0) 2934 goto out; 2935 w = w->w_hash_next; 2936 } 2937 2938 out: 2939 return (w); 2940 } 2941 2942 static void 2943 witness_hash_put(struct witness *w) 2944 { 2945 uint32_t hash; 2946 2947 MPASS(w != NULL); 2948 MPASS(w->w_name != NULL); 2949 if (witness_cold == 0) 2950 mtx_assert(&w_mtx, MA_OWNED); 2951 KASSERT(witness_hash_get(w->w_name) == NULL, 2952 ("%s: trying to add a hash entry that already exists!", __func__)); 2953 KASSERT(w->w_hash_next == NULL, 2954 ("%s: w->w_hash_next != NULL", __func__)); 2955 2956 hash = witness_hash_djb2(w->w_name, 0) % w_hash.wh_size; 2957 w->w_hash_next = w_hash.wh_array[hash]; 2958 w_hash.wh_array[hash] = w; 2959 w_hash.wh_count++; 2960 } 2961 2962 2963 static struct witness_lock_order_data * 2964 witness_lock_order_get(struct witness *parent, struct witness *child) 2965 { 2966 struct witness_lock_order_data *data = NULL; 2967 struct witness_lock_order_key key; 2968 unsigned int hash; 2969 2970 MPASS(parent != NULL && child != NULL); 2971 key.from = parent->w_index; 2972 key.to = child->w_index; 2973 WITNESS_INDEX_ASSERT(key.from); 2974 WITNESS_INDEX_ASSERT(key.to); 2975 if ((w_rmatrix[parent->w_index][child->w_index] 2976 & WITNESS_LOCK_ORDER_KNOWN) == 0) 2977 goto out; 2978 2979 hash = witness_hash_djb2((const char*)&key, 2980 sizeof(key)) % w_lohash.wloh_size; 2981 data = w_lohash.wloh_array[hash]; 2982 while (data != NULL) { 2983 if (witness_lock_order_key_equal(&data->wlod_key, &key)) 2984 break; 2985 data = data->wlod_next; 2986 } 2987 2988 out: 2989 return (data); 2990 } 2991 2992 /* 2993 * Verify that parent and child have a known relationship, are not the same, 2994 * and child is actually a child of parent. This is done without w_mtx 2995 * to avoid contention in the common case. 2996 */ 2997 static int 2998 witness_lock_order_check(struct witness *parent, struct witness *child) 2999 { 3000 3001 if (parent != child && 3002 w_rmatrix[parent->w_index][child->w_index] 3003 & WITNESS_LOCK_ORDER_KNOWN && 3004 isitmychild(parent, child)) 3005 return (1); 3006 3007 return (0); 3008 } 3009 3010 static int 3011 witness_lock_order_add(struct witness *parent, struct witness *child) 3012 { 3013 struct witness_lock_order_data *data = NULL; 3014 struct witness_lock_order_key key; 3015 unsigned int hash; 3016 3017 MPASS(parent != NULL && child != NULL); 3018 key.from = parent->w_index; 3019 key.to = child->w_index; 3020 WITNESS_INDEX_ASSERT(key.from); 3021 WITNESS_INDEX_ASSERT(key.to); 3022 if (w_rmatrix[parent->w_index][child->w_index] 3023 & WITNESS_LOCK_ORDER_KNOWN) 3024 return (1); 3025 3026 hash = witness_hash_djb2((const char*)&key, 3027 sizeof(key)) % w_lohash.wloh_size; 3028 w_rmatrix[parent->w_index][child->w_index] |= WITNESS_LOCK_ORDER_KNOWN; 3029 data = w_lofree; 3030 if (data == NULL) 3031 return (0); 3032 w_lofree = data->wlod_next; 3033 data->wlod_next = w_lohash.wloh_array[hash]; 3034 data->wlod_key = key; 3035 w_lohash.wloh_array[hash] = data; 3036 w_lohash.wloh_count++; 3037 stack_zero(&data->wlod_stack); 3038 stack_save(&data->wlod_stack); 3039 return (1); 3040 } 3041 3042 /* Call this whenever the structure of the witness graph changes. */ 3043 static void 3044 witness_increment_graph_generation(void) 3045 { 3046 3047 if (witness_cold == 0) 3048 mtx_assert(&w_mtx, MA_OWNED); 3049 w_generation++; 3050 } 3051 3052 static int 3053 witness_output_drain(void *arg __unused, const char *data, int len) 3054 { 3055 3056 witness_output("%.*s", len, data); 3057 return (len); 3058 } 3059 3060 static void 3061 witness_debugger(int cond, const char *msg) 3062 { 3063 char buf[32]; 3064 struct sbuf sb; 3065 struct stack st; 3066 3067 if (!cond) 3068 return; 3069 3070 if (witness_trace) { 3071 sbuf_new(&sb, buf, sizeof(buf), SBUF_FIXEDLEN); 3072 sbuf_set_drain(&sb, witness_output_drain, NULL); 3073 3074 stack_zero(&st); 3075 stack_save(&st); 3076 witness_output("stack backtrace:\n"); 3077 stack_sbuf_print_ddb(&sb, &st); 3078 3079 sbuf_finish(&sb); 3080 } 3081 3082 #ifdef KDB 3083 if (witness_kdb) 3084 kdb_enter(KDB_WHY_WITNESS, msg); 3085 #endif 3086 } 3087