1 /*- 2 * SPDX-License-Identifier: BSD-3-Clause 3 * 4 * Copyright (c) 2008 Isilon Systems, Inc. 5 * Copyright (c) 2008 Ilya Maykov <ivmaykov@gmail.com> 6 * Copyright (c) 1998 Berkeley Software Design, Inc. 7 * All rights reserved. 8 * 9 * Redistribution and use in source and binary forms, with or without 10 * modification, are permitted provided that the following conditions 11 * are met: 12 * 1. Redistributions of source code must retain the above copyright 13 * notice, this list of conditions and the following disclaimer. 14 * 2. Redistributions in binary form must reproduce the above copyright 15 * notice, this list of conditions and the following disclaimer in the 16 * documentation and/or other materials provided with the distribution. 17 * 3. Berkeley Software Design Inc's name may not be used to endorse or 18 * promote products derived from this software without specific prior 19 * written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY BERKELEY SOFTWARE DESIGN INC ``AS IS'' AND 22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24 * ARE DISCLAIMED. IN NO EVENT SHALL BERKELEY SOFTWARE DESIGN INC BE LIABLE 25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31 * SUCH DAMAGE. 32 * 33 * from BSDI $Id: mutex_witness.c,v 1.1.2.20 2000/04/27 03:10:27 cp Exp $ 34 * and BSDI $Id: synch_machdep.c,v 2.3.2.39 2000/04/27 03:10:25 cp Exp $ 35 */ 36 37 /* 38 * Implementation of the `witness' lock verifier. Originally implemented for 39 * mutexes in BSD/OS. Extended to handle generic lock objects and lock 40 * classes in FreeBSD. 41 */ 42 43 /* 44 * Main Entry: witness 45 * Pronunciation: 'wit-n&s 46 * Function: noun 47 * Etymology: Middle English witnesse, from Old English witnes knowledge, 48 * testimony, witness, from 2wit 49 * Date: before 12th century 50 * 1 : attestation of a fact or event : TESTIMONY 51 * 2 : one that gives evidence; specifically : one who testifies in 52 * a cause or before a judicial tribunal 53 * 3 : one asked to be present at a transaction so as to be able to 54 * testify to its having taken place 55 * 4 : one who has personal knowledge of something 56 * 5 a : something serving as evidence or proof : SIGN 57 * b : public affirmation by word or example of usually 58 * religious faith or conviction <the heroic witness to divine 59 * life -- Pilot> 60 * 6 capitalized : a member of the Jehovah's Witnesses 61 */ 62 63 /* 64 * Special rules concerning Giant and lock orders: 65 * 66 * 1) Giant must be acquired before any other mutexes. Stated another way, 67 * no other mutex may be held when Giant is acquired. 68 * 69 * 2) Giant must be released when blocking on a sleepable lock. 70 * 71 * This rule is less obvious, but is a result of Giant providing the same 72 * semantics as spl(). Basically, when a thread sleeps, it must release 73 * Giant. When a thread blocks on a sleepable lock, it sleeps. Hence rule 74 * 2). 75 * 76 * 3) Giant may be acquired before or after sleepable locks. 77 * 78 * This rule is also not quite as obvious. Giant may be acquired after 79 * a sleepable lock because it is a non-sleepable lock and non-sleepable 80 * locks may always be acquired while holding a sleepable lock. The second 81 * case, Giant before a sleepable lock, follows from rule 2) above. Suppose 82 * you have two threads T1 and T2 and a sleepable lock X. Suppose that T1 83 * acquires X and blocks on Giant. Then suppose that T2 acquires Giant and 84 * blocks on X. When T2 blocks on X, T2 will release Giant allowing T1 to 85 * execute. Thus, acquiring Giant both before and after a sleepable lock 86 * will not result in a lock order reversal. 87 */ 88 89 #include <sys/cdefs.h> 90 __FBSDID("$FreeBSD$"); 91 92 #include "opt_ddb.h" 93 #include "opt_hwpmc_hooks.h" 94 #include "opt_stack.h" 95 #include "opt_witness.h" 96 97 #include <sys/param.h> 98 #include <sys/bus.h> 99 #include <sys/kdb.h> 100 #include <sys/kernel.h> 101 #include <sys/ktr.h> 102 #include <sys/lock.h> 103 #include <sys/malloc.h> 104 #include <sys/mutex.h> 105 #include <sys/priv.h> 106 #include <sys/proc.h> 107 #include <sys/sbuf.h> 108 #include <sys/sched.h> 109 #include <sys/stack.h> 110 #include <sys/sysctl.h> 111 #include <sys/syslog.h> 112 #include <sys/systm.h> 113 114 #ifdef DDB 115 #include <ddb/ddb.h> 116 #endif 117 118 #include <machine/stdarg.h> 119 120 #if !defined(DDB) && !defined(STACK) 121 #error "DDB or STACK options are required for WITNESS" 122 #endif 123 124 /* Note that these traces do not work with KTR_ALQ. */ 125 #if 0 126 #define KTR_WITNESS KTR_SUBSYS 127 #else 128 #define KTR_WITNESS 0 129 #endif 130 131 #define LI_RECURSEMASK 0x0000ffff /* Recursion depth of lock instance. */ 132 #define LI_EXCLUSIVE 0x00010000 /* Exclusive lock instance. */ 133 #define LI_NORELEASE 0x00020000 /* Lock not allowed to be released. */ 134 135 /* Define this to check for blessed mutexes */ 136 #undef BLESSING 137 138 #ifndef WITNESS_COUNT 139 #define WITNESS_COUNT 1536 140 #endif 141 #define WITNESS_HASH_SIZE 251 /* Prime, gives load factor < 2 */ 142 #define WITNESS_PENDLIST (512 + (MAXCPU * 4)) 143 144 /* Allocate 256 KB of stack data space */ 145 #define WITNESS_LO_DATA_COUNT 2048 146 147 /* Prime, gives load factor of ~2 at full load */ 148 #define WITNESS_LO_HASH_SIZE 1021 149 150 /* 151 * XXX: This is somewhat bogus, as we assume here that at most 2048 threads 152 * will hold LOCK_NCHILDREN locks. We handle failure ok, and we should 153 * probably be safe for the most part, but it's still a SWAG. 154 */ 155 #define LOCK_NCHILDREN 5 156 #define LOCK_CHILDCOUNT 2048 157 158 #define MAX_W_NAME 64 159 160 #define FULLGRAPH_SBUF_SIZE 512 161 162 /* 163 * These flags go in the witness relationship matrix and describe the 164 * relationship between any two struct witness objects. 165 */ 166 #define WITNESS_UNRELATED 0x00 /* No lock order relation. */ 167 #define WITNESS_PARENT 0x01 /* Parent, aka direct ancestor. */ 168 #define WITNESS_ANCESTOR 0x02 /* Direct or indirect ancestor. */ 169 #define WITNESS_CHILD 0x04 /* Child, aka direct descendant. */ 170 #define WITNESS_DESCENDANT 0x08 /* Direct or indirect descendant. */ 171 #define WITNESS_ANCESTOR_MASK (WITNESS_PARENT | WITNESS_ANCESTOR) 172 #define WITNESS_DESCENDANT_MASK (WITNESS_CHILD | WITNESS_DESCENDANT) 173 #define WITNESS_RELATED_MASK \ 174 (WITNESS_ANCESTOR_MASK | WITNESS_DESCENDANT_MASK) 175 #define WITNESS_REVERSAL 0x10 /* A lock order reversal has been 176 * observed. */ 177 #define WITNESS_RESERVED1 0x20 /* Unused flag, reserved. */ 178 #define WITNESS_RESERVED2 0x40 /* Unused flag, reserved. */ 179 #define WITNESS_LOCK_ORDER_KNOWN 0x80 /* This lock order is known. */ 180 181 /* Descendant to ancestor flags */ 182 #define WITNESS_DTOA(x) (((x) & WITNESS_RELATED_MASK) >> 2) 183 184 /* Ancestor to descendant flags */ 185 #define WITNESS_ATOD(x) (((x) & WITNESS_RELATED_MASK) << 2) 186 187 #define WITNESS_INDEX_ASSERT(i) \ 188 MPASS((i) > 0 && (i) <= w_max_used_index && (i) < witness_count) 189 190 static MALLOC_DEFINE(M_WITNESS, "Witness", "Witness"); 191 192 /* 193 * Lock instances. A lock instance is the data associated with a lock while 194 * it is held by witness. For example, a lock instance will hold the 195 * recursion count of a lock. Lock instances are held in lists. Spin locks 196 * are held in a per-cpu list while sleep locks are held in per-thread list. 197 */ 198 struct lock_instance { 199 struct lock_object *li_lock; 200 const char *li_file; 201 int li_line; 202 u_int li_flags; 203 }; 204 205 /* 206 * A simple list type used to build the list of locks held by a thread 207 * or CPU. We can't simply embed the list in struct lock_object since a 208 * lock may be held by more than one thread if it is a shared lock. Locks 209 * are added to the head of the list, so we fill up each list entry from 210 * "the back" logically. To ease some of the arithmetic, we actually fill 211 * in each list entry the normal way (children[0] then children[1], etc.) but 212 * when we traverse the list we read children[count-1] as the first entry 213 * down to children[0] as the final entry. 214 */ 215 struct lock_list_entry { 216 struct lock_list_entry *ll_next; 217 struct lock_instance ll_children[LOCK_NCHILDREN]; 218 u_int ll_count; 219 }; 220 221 /* 222 * The main witness structure. One of these per named lock type in the system 223 * (for example, "vnode interlock"). 224 */ 225 struct witness { 226 char w_name[MAX_W_NAME]; 227 uint32_t w_index; /* Index in the relationship matrix */ 228 struct lock_class *w_class; 229 STAILQ_ENTRY(witness) w_list; /* List of all witnesses. */ 230 STAILQ_ENTRY(witness) w_typelist; /* Witnesses of a type. */ 231 struct witness *w_hash_next; /* Linked list in hash buckets. */ 232 const char *w_file; /* File where last acquired */ 233 uint32_t w_line; /* Line where last acquired */ 234 uint32_t w_refcount; 235 uint16_t w_num_ancestors; /* direct/indirect 236 * ancestor count */ 237 uint16_t w_num_descendants; /* direct/indirect 238 * descendant count */ 239 int16_t w_ddb_level; 240 unsigned w_displayed:1; 241 unsigned w_reversed:1; 242 }; 243 244 STAILQ_HEAD(witness_list, witness); 245 246 /* 247 * The witness hash table. Keys are witness names (const char *), elements are 248 * witness objects (struct witness *). 249 */ 250 struct witness_hash { 251 struct witness *wh_array[WITNESS_HASH_SIZE]; 252 uint32_t wh_size; 253 uint32_t wh_count; 254 }; 255 256 /* 257 * Key type for the lock order data hash table. 258 */ 259 struct witness_lock_order_key { 260 uint16_t from; 261 uint16_t to; 262 }; 263 264 struct witness_lock_order_data { 265 struct stack wlod_stack; 266 struct witness_lock_order_key wlod_key; 267 struct witness_lock_order_data *wlod_next; 268 }; 269 270 /* 271 * The witness lock order data hash table. Keys are witness index tuples 272 * (struct witness_lock_order_key), elements are lock order data objects 273 * (struct witness_lock_order_data). 274 */ 275 struct witness_lock_order_hash { 276 struct witness_lock_order_data *wloh_array[WITNESS_LO_HASH_SIZE]; 277 u_int wloh_size; 278 u_int wloh_count; 279 }; 280 281 #ifdef BLESSING 282 struct witness_blessed { 283 const char *b_lock1; 284 const char *b_lock2; 285 }; 286 #endif 287 288 struct witness_pendhelp { 289 const char *wh_type; 290 struct lock_object *wh_lock; 291 }; 292 293 struct witness_order_list_entry { 294 const char *w_name; 295 struct lock_class *w_class; 296 }; 297 298 /* 299 * Returns 0 if one of the locks is a spin lock and the other is not. 300 * Returns 1 otherwise. 301 */ 302 static __inline int 303 witness_lock_type_equal(struct witness *w1, struct witness *w2) 304 { 305 306 return ((w1->w_class->lc_flags & (LC_SLEEPLOCK | LC_SPINLOCK)) == 307 (w2->w_class->lc_flags & (LC_SLEEPLOCK | LC_SPINLOCK))); 308 } 309 310 static __inline int 311 witness_lock_order_key_equal(const struct witness_lock_order_key *a, 312 const struct witness_lock_order_key *b) 313 { 314 315 return (a->from == b->from && a->to == b->to); 316 } 317 318 static int _isitmyx(struct witness *w1, struct witness *w2, int rmask, 319 const char *fname); 320 static void adopt(struct witness *parent, struct witness *child); 321 #ifdef BLESSING 322 static int blessed(struct witness *, struct witness *); 323 #endif 324 static void depart(struct witness *w); 325 static struct witness *enroll(const char *description, 326 struct lock_class *lock_class); 327 static struct lock_instance *find_instance(struct lock_list_entry *list, 328 const struct lock_object *lock); 329 static int isitmychild(struct witness *parent, struct witness *child); 330 static int isitmydescendant(struct witness *parent, struct witness *child); 331 static void itismychild(struct witness *parent, struct witness *child); 332 static int sysctl_debug_witness_badstacks(SYSCTL_HANDLER_ARGS); 333 static int sysctl_debug_witness_watch(SYSCTL_HANDLER_ARGS); 334 static int sysctl_debug_witness_fullgraph(SYSCTL_HANDLER_ARGS); 335 static int sysctl_debug_witness_channel(SYSCTL_HANDLER_ARGS); 336 static void witness_add_fullgraph(struct sbuf *sb, struct witness *parent); 337 #ifdef DDB 338 static void witness_ddb_compute_levels(void); 339 static void witness_ddb_display(int(*)(const char *fmt, ...)); 340 static void witness_ddb_display_descendants(int(*)(const char *fmt, ...), 341 struct witness *, int indent); 342 static void witness_ddb_display_list(int(*prnt)(const char *fmt, ...), 343 struct witness_list *list); 344 static void witness_ddb_level_descendants(struct witness *parent, int l); 345 static void witness_ddb_list(struct thread *td); 346 #endif 347 static void witness_debugger(int cond, const char *msg); 348 static void witness_free(struct witness *m); 349 static struct witness *witness_get(void); 350 static uint32_t witness_hash_djb2(const uint8_t *key, uint32_t size); 351 static struct witness *witness_hash_get(const char *key); 352 static void witness_hash_put(struct witness *w); 353 static void witness_init_hash_tables(void); 354 static void witness_increment_graph_generation(void); 355 static void witness_lock_list_free(struct lock_list_entry *lle); 356 static struct lock_list_entry *witness_lock_list_get(void); 357 static int witness_lock_order_add(struct witness *parent, 358 struct witness *child); 359 static int witness_lock_order_check(struct witness *parent, 360 struct witness *child); 361 static struct witness_lock_order_data *witness_lock_order_get( 362 struct witness *parent, 363 struct witness *child); 364 static void witness_list_lock(struct lock_instance *instance, 365 int (*prnt)(const char *fmt, ...)); 366 static int witness_output(const char *fmt, ...) __printflike(1, 2); 367 static int witness_voutput(const char *fmt, va_list ap) __printflike(1, 0); 368 static void witness_setflag(struct lock_object *lock, int flag, int set); 369 370 static SYSCTL_NODE(_debug, OID_AUTO, witness, CTLFLAG_RW, NULL, 371 "Witness Locking"); 372 373 /* 374 * If set to 0, lock order checking is disabled. If set to -1, 375 * witness is completely disabled. Otherwise witness performs full 376 * lock order checking for all locks. At runtime, lock order checking 377 * may be toggled. However, witness cannot be reenabled once it is 378 * completely disabled. 379 */ 380 static int witness_watch = 1; 381 SYSCTL_PROC(_debug_witness, OID_AUTO, watch, CTLFLAG_RWTUN | CTLTYPE_INT, NULL, 0, 382 sysctl_debug_witness_watch, "I", "witness is watching lock operations"); 383 384 #ifdef KDB 385 /* 386 * When KDB is enabled and witness_kdb is 1, it will cause the system 387 * to drop into kdebug() when: 388 * - a lock hierarchy violation occurs 389 * - locks are held when going to sleep. 390 */ 391 #ifdef WITNESS_KDB 392 int witness_kdb = 1; 393 #else 394 int witness_kdb = 0; 395 #endif 396 SYSCTL_INT(_debug_witness, OID_AUTO, kdb, CTLFLAG_RWTUN, &witness_kdb, 0, ""); 397 #endif /* KDB */ 398 399 #if defined(DDB) || defined(KDB) 400 /* 401 * When DDB or KDB is enabled and witness_trace is 1, it will cause the system 402 * to print a stack trace: 403 * - a lock hierarchy violation occurs 404 * - locks are held when going to sleep. 405 */ 406 int witness_trace = 1; 407 SYSCTL_INT(_debug_witness, OID_AUTO, trace, CTLFLAG_RWTUN, &witness_trace, 0, ""); 408 #endif /* DDB || KDB */ 409 410 #ifdef WITNESS_SKIPSPIN 411 int witness_skipspin = 1; 412 #else 413 int witness_skipspin = 0; 414 #endif 415 SYSCTL_INT(_debug_witness, OID_AUTO, skipspin, CTLFLAG_RDTUN, &witness_skipspin, 0, ""); 416 417 int badstack_sbuf_size; 418 419 int witness_count = WITNESS_COUNT; 420 SYSCTL_INT(_debug_witness, OID_AUTO, witness_count, CTLFLAG_RDTUN, 421 &witness_count, 0, ""); 422 423 /* 424 * Output channel for witness messages. By default we print to the console. 425 */ 426 enum witness_channel { 427 WITNESS_CONSOLE, 428 WITNESS_LOG, 429 WITNESS_NONE, 430 }; 431 432 static enum witness_channel witness_channel = WITNESS_CONSOLE; 433 SYSCTL_PROC(_debug_witness, OID_AUTO, output_channel, CTLTYPE_STRING | 434 CTLFLAG_RWTUN, NULL, 0, sysctl_debug_witness_channel, "A", 435 "Output channel for warnings"); 436 437 /* 438 * Call this to print out the relations between locks. 439 */ 440 SYSCTL_PROC(_debug_witness, OID_AUTO, fullgraph, CTLTYPE_STRING | CTLFLAG_RD, 441 NULL, 0, sysctl_debug_witness_fullgraph, "A", "Show locks relation graphs"); 442 443 /* 444 * Call this to print out the witness faulty stacks. 445 */ 446 SYSCTL_PROC(_debug_witness, OID_AUTO, badstacks, CTLTYPE_STRING | CTLFLAG_RD, 447 NULL, 0, sysctl_debug_witness_badstacks, "A", "Show bad witness stacks"); 448 449 static struct mtx w_mtx; 450 451 /* w_list */ 452 static struct witness_list w_free = STAILQ_HEAD_INITIALIZER(w_free); 453 static struct witness_list w_all = STAILQ_HEAD_INITIALIZER(w_all); 454 455 /* w_typelist */ 456 static struct witness_list w_spin = STAILQ_HEAD_INITIALIZER(w_spin); 457 static struct witness_list w_sleep = STAILQ_HEAD_INITIALIZER(w_sleep); 458 459 /* lock list */ 460 static struct lock_list_entry *w_lock_list_free = NULL; 461 static struct witness_pendhelp pending_locks[WITNESS_PENDLIST]; 462 static u_int pending_cnt; 463 464 static int w_free_cnt, w_spin_cnt, w_sleep_cnt; 465 SYSCTL_INT(_debug_witness, OID_AUTO, free_cnt, CTLFLAG_RD, &w_free_cnt, 0, ""); 466 SYSCTL_INT(_debug_witness, OID_AUTO, spin_cnt, CTLFLAG_RD, &w_spin_cnt, 0, ""); 467 SYSCTL_INT(_debug_witness, OID_AUTO, sleep_cnt, CTLFLAG_RD, &w_sleep_cnt, 0, 468 ""); 469 470 static struct witness *w_data; 471 static uint8_t **w_rmatrix; 472 static struct lock_list_entry w_locklistdata[LOCK_CHILDCOUNT]; 473 static struct witness_hash w_hash; /* The witness hash table. */ 474 475 /* The lock order data hash */ 476 static struct witness_lock_order_data w_lodata[WITNESS_LO_DATA_COUNT]; 477 static struct witness_lock_order_data *w_lofree = NULL; 478 static struct witness_lock_order_hash w_lohash; 479 static int w_max_used_index = 0; 480 static unsigned int w_generation = 0; 481 static const char w_notrunning[] = "Witness not running\n"; 482 static const char w_stillcold[] = "Witness is still cold\n"; 483 #ifdef __i386__ 484 static const char w_notallowed[] = "The sysctl is disabled on the arch\n"; 485 #endif 486 487 static struct witness_order_list_entry order_lists[] = { 488 /* 489 * sx locks 490 */ 491 { "proctree", &lock_class_sx }, 492 { "allproc", &lock_class_sx }, 493 { "allprison", &lock_class_sx }, 494 { NULL, NULL }, 495 /* 496 * Various mutexes 497 */ 498 { "Giant", &lock_class_mtx_sleep }, 499 { "pipe mutex", &lock_class_mtx_sleep }, 500 { "sigio lock", &lock_class_mtx_sleep }, 501 { "process group", &lock_class_mtx_sleep }, 502 { "process lock", &lock_class_mtx_sleep }, 503 { "session", &lock_class_mtx_sleep }, 504 { "uidinfo hash", &lock_class_rw }, 505 #ifdef HWPMC_HOOKS 506 { "pmc-sleep", &lock_class_mtx_sleep }, 507 #endif 508 { "time lock", &lock_class_mtx_sleep }, 509 { NULL, NULL }, 510 /* 511 * umtx 512 */ 513 { "umtx lock", &lock_class_mtx_sleep }, 514 { NULL, NULL }, 515 /* 516 * Sockets 517 */ 518 { "accept", &lock_class_mtx_sleep }, 519 { "so_snd", &lock_class_mtx_sleep }, 520 { "so_rcv", &lock_class_mtx_sleep }, 521 { "sellck", &lock_class_mtx_sleep }, 522 { NULL, NULL }, 523 /* 524 * Routing 525 */ 526 { "so_rcv", &lock_class_mtx_sleep }, 527 { "radix node head", &lock_class_rw }, 528 { "rtentry", &lock_class_mtx_sleep }, 529 { "ifaddr", &lock_class_mtx_sleep }, 530 { NULL, NULL }, 531 /* 532 * IPv4 multicast: 533 * protocol locks before interface locks, after UDP locks. 534 */ 535 { "in_multi_sx", &lock_class_sx }, 536 { "udpinp", &lock_class_rw }, 537 { "in_multi_list_mtx", &lock_class_mtx_sleep }, 538 { "igmp_mtx", &lock_class_mtx_sleep }, 539 { "ifnet_rw", &lock_class_rw }, 540 { "if_addr_lock", &lock_class_rw }, 541 { NULL, NULL }, 542 /* 543 * IPv6 multicast: 544 * protocol locks before interface locks, after UDP locks. 545 */ 546 { "in6_multi_sx", &lock_class_sx }, 547 { "udpinp", &lock_class_rw }, 548 { "in6_multi_list_mtx", &lock_class_mtx_sleep }, 549 { "mld_mtx", &lock_class_mtx_sleep }, 550 { "ifnet_rw", &lock_class_rw }, 551 { "if_addr_lock", &lock_class_rw }, 552 { NULL, NULL }, 553 /* 554 * UNIX Domain Sockets 555 */ 556 { "unp_link_rwlock", &lock_class_rw }, 557 { "unp_list_lock", &lock_class_mtx_sleep }, 558 { "unp", &lock_class_mtx_sleep }, 559 { "so_snd", &lock_class_mtx_sleep }, 560 { NULL, NULL }, 561 /* 562 * UDP/IP 563 */ 564 { "udp", &lock_class_rw }, 565 { "udpinp", &lock_class_rw }, 566 { "so_snd", &lock_class_mtx_sleep }, 567 { NULL, NULL }, 568 /* 569 * TCP/IP 570 */ 571 { "tcp", &lock_class_rw }, 572 { "tcpinp", &lock_class_rw }, 573 { "so_snd", &lock_class_mtx_sleep }, 574 { NULL, NULL }, 575 /* 576 * BPF 577 */ 578 { "bpf global lock", &lock_class_sx }, 579 { "bpf interface lock", &lock_class_rw }, 580 { "bpf cdev lock", &lock_class_mtx_sleep }, 581 { NULL, NULL }, 582 /* 583 * NFS server 584 */ 585 { "nfsd_mtx", &lock_class_mtx_sleep }, 586 { "so_snd", &lock_class_mtx_sleep }, 587 { NULL, NULL }, 588 589 /* 590 * IEEE 802.11 591 */ 592 { "802.11 com lock", &lock_class_mtx_sleep}, 593 { NULL, NULL }, 594 /* 595 * Network drivers 596 */ 597 { "network driver", &lock_class_mtx_sleep}, 598 { NULL, NULL }, 599 600 /* 601 * Netgraph 602 */ 603 { "ng_node", &lock_class_mtx_sleep }, 604 { "ng_worklist", &lock_class_mtx_sleep }, 605 { NULL, NULL }, 606 /* 607 * CDEV 608 */ 609 { "vm map (system)", &lock_class_mtx_sleep }, 610 { "vnode interlock", &lock_class_mtx_sleep }, 611 { "cdev", &lock_class_mtx_sleep }, 612 { NULL, NULL }, 613 /* 614 * VM 615 */ 616 { "vm map (user)", &lock_class_sx }, 617 { "vm object", &lock_class_rw }, 618 { "vm page", &lock_class_mtx_sleep }, 619 { "pmap pv global", &lock_class_rw }, 620 { "pmap", &lock_class_mtx_sleep }, 621 { "pmap pv list", &lock_class_rw }, 622 { "vm page free queue", &lock_class_mtx_sleep }, 623 { "vm pagequeue", &lock_class_mtx_sleep }, 624 { NULL, NULL }, 625 /* 626 * kqueue/VFS interaction 627 */ 628 { "kqueue", &lock_class_mtx_sleep }, 629 { "struct mount mtx", &lock_class_mtx_sleep }, 630 { "vnode interlock", &lock_class_mtx_sleep }, 631 { NULL, NULL }, 632 /* 633 * VFS namecache 634 */ 635 { "ncvn", &lock_class_mtx_sleep }, 636 { "ncbuc", &lock_class_rw }, 637 { "vnode interlock", &lock_class_mtx_sleep }, 638 { "ncneg", &lock_class_mtx_sleep }, 639 { NULL, NULL }, 640 /* 641 * ZFS locking 642 */ 643 { "dn->dn_mtx", &lock_class_sx }, 644 { "dr->dt.di.dr_mtx", &lock_class_sx }, 645 { "db->db_mtx", &lock_class_sx }, 646 { NULL, NULL }, 647 /* 648 * TCP log locks 649 */ 650 { "TCP ID tree", &lock_class_rw }, 651 { "tcp log id bucket", &lock_class_mtx_sleep }, 652 { "tcpinp", &lock_class_rw }, 653 { "TCP log expireq", &lock_class_mtx_sleep }, 654 { NULL, NULL }, 655 /* 656 * spin locks 657 */ 658 #ifdef SMP 659 { "ap boot", &lock_class_mtx_spin }, 660 #endif 661 { "rm.mutex_mtx", &lock_class_mtx_spin }, 662 { "sio", &lock_class_mtx_spin }, 663 #ifdef __i386__ 664 { "cy", &lock_class_mtx_spin }, 665 #endif 666 #ifdef __sparc64__ 667 { "pcib_mtx", &lock_class_mtx_spin }, 668 { "rtc_mtx", &lock_class_mtx_spin }, 669 #endif 670 { "scc_hwmtx", &lock_class_mtx_spin }, 671 { "uart_hwmtx", &lock_class_mtx_spin }, 672 { "fast_taskqueue", &lock_class_mtx_spin }, 673 { "intr table", &lock_class_mtx_spin }, 674 #ifdef HWPMC_HOOKS 675 { "pmc-per-proc", &lock_class_mtx_spin }, 676 #endif 677 { "process slock", &lock_class_mtx_spin }, 678 { "syscons video lock", &lock_class_mtx_spin }, 679 { "sleepq chain", &lock_class_mtx_spin }, 680 { "rm_spinlock", &lock_class_mtx_spin }, 681 { "turnstile chain", &lock_class_mtx_spin }, 682 { "turnstile lock", &lock_class_mtx_spin }, 683 { "sched lock", &lock_class_mtx_spin }, 684 { "td_contested", &lock_class_mtx_spin }, 685 { "callout", &lock_class_mtx_spin }, 686 { "entropy harvest mutex", &lock_class_mtx_spin }, 687 #ifdef SMP 688 { "smp rendezvous", &lock_class_mtx_spin }, 689 #endif 690 #ifdef __powerpc__ 691 { "tlb0", &lock_class_mtx_spin }, 692 #endif 693 /* 694 * leaf locks 695 */ 696 { "intrcnt", &lock_class_mtx_spin }, 697 { "icu", &lock_class_mtx_spin }, 698 #if defined(SMP) && defined(__sparc64__) 699 { "ipi", &lock_class_mtx_spin }, 700 #endif 701 #ifdef __i386__ 702 { "allpmaps", &lock_class_mtx_spin }, 703 { "descriptor tables", &lock_class_mtx_spin }, 704 #endif 705 { "clk", &lock_class_mtx_spin }, 706 { "cpuset", &lock_class_mtx_spin }, 707 { "mprof lock", &lock_class_mtx_spin }, 708 { "zombie lock", &lock_class_mtx_spin }, 709 { "ALD Queue", &lock_class_mtx_spin }, 710 #if defined(__i386__) || defined(__amd64__) 711 { "pcicfg", &lock_class_mtx_spin }, 712 { "NDIS thread lock", &lock_class_mtx_spin }, 713 #endif 714 { "tw_osl_io_lock", &lock_class_mtx_spin }, 715 { "tw_osl_q_lock", &lock_class_mtx_spin }, 716 { "tw_cl_io_lock", &lock_class_mtx_spin }, 717 { "tw_cl_intr_lock", &lock_class_mtx_spin }, 718 { "tw_cl_gen_lock", &lock_class_mtx_spin }, 719 #ifdef HWPMC_HOOKS 720 { "pmc-leaf", &lock_class_mtx_spin }, 721 #endif 722 { "blocked lock", &lock_class_mtx_spin }, 723 { NULL, NULL }, 724 { NULL, NULL } 725 }; 726 727 #ifdef BLESSING 728 /* 729 * Pairs of locks which have been blessed 730 * Don't complain about order problems with blessed locks 731 */ 732 static struct witness_blessed blessed_list[] = { 733 }; 734 #endif 735 736 /* 737 * This global is set to 0 once it becomes safe to use the witness code. 738 */ 739 static int witness_cold = 1; 740 741 /* 742 * This global is set to 1 once the static lock orders have been enrolled 743 * so that a warning can be issued for any spin locks enrolled later. 744 */ 745 static int witness_spin_warn = 0; 746 747 /* Trim useless garbage from filenames. */ 748 static const char * 749 fixup_filename(const char *file) 750 { 751 752 if (file == NULL) 753 return (NULL); 754 while (strncmp(file, "../", 3) == 0) 755 file += 3; 756 return (file); 757 } 758 759 /* 760 * Calculate the size of early witness structures. 761 */ 762 int 763 witness_startup_count(void) 764 { 765 int sz; 766 767 sz = sizeof(struct witness) * witness_count; 768 sz += sizeof(*w_rmatrix) * (witness_count + 1); 769 sz += sizeof(*w_rmatrix[0]) * (witness_count + 1) * 770 (witness_count + 1); 771 772 return (sz); 773 } 774 775 /* 776 * The WITNESS-enabled diagnostic code. Note that the witness code does 777 * assume that the early boot is single-threaded at least until after this 778 * routine is completed. 779 */ 780 void 781 witness_startup(void *mem) 782 { 783 struct lock_object *lock; 784 struct witness_order_list_entry *order; 785 struct witness *w, *w1; 786 uintptr_t p; 787 int i; 788 789 p = (uintptr_t)mem; 790 w_data = (void *)p; 791 p += sizeof(struct witness) * witness_count; 792 793 w_rmatrix = (void *)p; 794 p += sizeof(*w_rmatrix) * (witness_count + 1); 795 796 for (i = 0; i < witness_count + 1; i++) { 797 w_rmatrix[i] = (void *)p; 798 p += sizeof(*w_rmatrix[i]) * (witness_count + 1); 799 } 800 badstack_sbuf_size = witness_count * 256; 801 802 /* 803 * We have to release Giant before initializing its witness 804 * structure so that WITNESS doesn't get confused. 805 */ 806 mtx_unlock(&Giant); 807 mtx_assert(&Giant, MA_NOTOWNED); 808 809 CTR1(KTR_WITNESS, "%s: initializing witness", __func__); 810 mtx_init(&w_mtx, "witness lock", NULL, MTX_SPIN | MTX_QUIET | 811 MTX_NOWITNESS | MTX_NOPROFILE); 812 for (i = witness_count - 1; i >= 0; i--) { 813 w = &w_data[i]; 814 memset(w, 0, sizeof(*w)); 815 w_data[i].w_index = i; /* Witness index never changes. */ 816 witness_free(w); 817 } 818 KASSERT(STAILQ_FIRST(&w_free)->w_index == 0, 819 ("%s: Invalid list of free witness objects", __func__)); 820 821 /* Witness with index 0 is not used to aid in debugging. */ 822 STAILQ_REMOVE_HEAD(&w_free, w_list); 823 w_free_cnt--; 824 825 for (i = 0; i < witness_count; i++) { 826 memset(w_rmatrix[i], 0, sizeof(*w_rmatrix[i]) * 827 (witness_count + 1)); 828 } 829 830 for (i = 0; i < LOCK_CHILDCOUNT; i++) 831 witness_lock_list_free(&w_locklistdata[i]); 832 witness_init_hash_tables(); 833 834 /* First add in all the specified order lists. */ 835 for (order = order_lists; order->w_name != NULL; order++) { 836 w = enroll(order->w_name, order->w_class); 837 if (w == NULL) 838 continue; 839 w->w_file = "order list"; 840 for (order++; order->w_name != NULL; order++) { 841 w1 = enroll(order->w_name, order->w_class); 842 if (w1 == NULL) 843 continue; 844 w1->w_file = "order list"; 845 itismychild(w, w1); 846 w = w1; 847 } 848 } 849 witness_spin_warn = 1; 850 851 /* Iterate through all locks and add them to witness. */ 852 for (i = 0; pending_locks[i].wh_lock != NULL; i++) { 853 lock = pending_locks[i].wh_lock; 854 KASSERT(lock->lo_flags & LO_WITNESS, 855 ("%s: lock %s is on pending list but not LO_WITNESS", 856 __func__, lock->lo_name)); 857 lock->lo_witness = enroll(pending_locks[i].wh_type, 858 LOCK_CLASS(lock)); 859 } 860 861 /* Mark the witness code as being ready for use. */ 862 witness_cold = 0; 863 864 mtx_lock(&Giant); 865 } 866 867 void 868 witness_init(struct lock_object *lock, const char *type) 869 { 870 struct lock_class *class; 871 872 /* Various sanity checks. */ 873 class = LOCK_CLASS(lock); 874 if ((lock->lo_flags & LO_RECURSABLE) != 0 && 875 (class->lc_flags & LC_RECURSABLE) == 0) 876 kassert_panic("%s: lock (%s) %s can not be recursable", 877 __func__, class->lc_name, lock->lo_name); 878 if ((lock->lo_flags & LO_SLEEPABLE) != 0 && 879 (class->lc_flags & LC_SLEEPABLE) == 0) 880 kassert_panic("%s: lock (%s) %s can not be sleepable", 881 __func__, class->lc_name, lock->lo_name); 882 if ((lock->lo_flags & LO_UPGRADABLE) != 0 && 883 (class->lc_flags & LC_UPGRADABLE) == 0) 884 kassert_panic("%s: lock (%s) %s can not be upgradable", 885 __func__, class->lc_name, lock->lo_name); 886 887 /* 888 * If we shouldn't watch this lock, then just clear lo_witness. 889 * Otherwise, if witness_cold is set, then it is too early to 890 * enroll this lock, so defer it to witness_initialize() by adding 891 * it to the pending_locks list. If it is not too early, then enroll 892 * the lock now. 893 */ 894 if (witness_watch < 1 || panicstr != NULL || 895 (lock->lo_flags & LO_WITNESS) == 0) 896 lock->lo_witness = NULL; 897 else if (witness_cold) { 898 pending_locks[pending_cnt].wh_lock = lock; 899 pending_locks[pending_cnt++].wh_type = type; 900 if (pending_cnt > WITNESS_PENDLIST) 901 panic("%s: pending locks list is too small, " 902 "increase WITNESS_PENDLIST\n", 903 __func__); 904 } else 905 lock->lo_witness = enroll(type, class); 906 } 907 908 void 909 witness_destroy(struct lock_object *lock) 910 { 911 struct lock_class *class; 912 struct witness *w; 913 914 class = LOCK_CLASS(lock); 915 916 if (witness_cold) 917 panic("lock (%s) %s destroyed while witness_cold", 918 class->lc_name, lock->lo_name); 919 920 /* XXX: need to verify that no one holds the lock */ 921 if ((lock->lo_flags & LO_WITNESS) == 0 || lock->lo_witness == NULL) 922 return; 923 w = lock->lo_witness; 924 925 mtx_lock_spin(&w_mtx); 926 MPASS(w->w_refcount > 0); 927 w->w_refcount--; 928 929 if (w->w_refcount == 0) 930 depart(w); 931 mtx_unlock_spin(&w_mtx); 932 } 933 934 #ifdef DDB 935 static void 936 witness_ddb_compute_levels(void) 937 { 938 struct witness *w; 939 940 /* 941 * First clear all levels. 942 */ 943 STAILQ_FOREACH(w, &w_all, w_list) 944 w->w_ddb_level = -1; 945 946 /* 947 * Look for locks with no parents and level all their descendants. 948 */ 949 STAILQ_FOREACH(w, &w_all, w_list) { 950 951 /* If the witness has ancestors (is not a root), skip it. */ 952 if (w->w_num_ancestors > 0) 953 continue; 954 witness_ddb_level_descendants(w, 0); 955 } 956 } 957 958 static void 959 witness_ddb_level_descendants(struct witness *w, int l) 960 { 961 int i; 962 963 if (w->w_ddb_level >= l) 964 return; 965 966 w->w_ddb_level = l; 967 l++; 968 969 for (i = 1; i <= w_max_used_index; i++) { 970 if (w_rmatrix[w->w_index][i] & WITNESS_PARENT) 971 witness_ddb_level_descendants(&w_data[i], l); 972 } 973 } 974 975 static void 976 witness_ddb_display_descendants(int(*prnt)(const char *fmt, ...), 977 struct witness *w, int indent) 978 { 979 int i; 980 981 for (i = 0; i < indent; i++) 982 prnt(" "); 983 prnt("%s (type: %s, depth: %d, active refs: %d)", 984 w->w_name, w->w_class->lc_name, 985 w->w_ddb_level, w->w_refcount); 986 if (w->w_displayed) { 987 prnt(" -- (already displayed)\n"); 988 return; 989 } 990 w->w_displayed = 1; 991 if (w->w_file != NULL && w->w_line != 0) 992 prnt(" -- last acquired @ %s:%d\n", fixup_filename(w->w_file), 993 w->w_line); 994 else 995 prnt(" -- never acquired\n"); 996 indent++; 997 WITNESS_INDEX_ASSERT(w->w_index); 998 for (i = 1; i <= w_max_used_index; i++) { 999 if (db_pager_quit) 1000 return; 1001 if (w_rmatrix[w->w_index][i] & WITNESS_PARENT) 1002 witness_ddb_display_descendants(prnt, &w_data[i], 1003 indent); 1004 } 1005 } 1006 1007 static void 1008 witness_ddb_display_list(int(*prnt)(const char *fmt, ...), 1009 struct witness_list *list) 1010 { 1011 struct witness *w; 1012 1013 STAILQ_FOREACH(w, list, w_typelist) { 1014 if (w->w_file == NULL || w->w_ddb_level > 0) 1015 continue; 1016 1017 /* This lock has no anscestors - display its descendants. */ 1018 witness_ddb_display_descendants(prnt, w, 0); 1019 if (db_pager_quit) 1020 return; 1021 } 1022 } 1023 1024 static void 1025 witness_ddb_display(int(*prnt)(const char *fmt, ...)) 1026 { 1027 struct witness *w; 1028 1029 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); 1030 witness_ddb_compute_levels(); 1031 1032 /* Clear all the displayed flags. */ 1033 STAILQ_FOREACH(w, &w_all, w_list) 1034 w->w_displayed = 0; 1035 1036 /* 1037 * First, handle sleep locks which have been acquired at least 1038 * once. 1039 */ 1040 prnt("Sleep locks:\n"); 1041 witness_ddb_display_list(prnt, &w_sleep); 1042 if (db_pager_quit) 1043 return; 1044 1045 /* 1046 * Now do spin locks which have been acquired at least once. 1047 */ 1048 prnt("\nSpin locks:\n"); 1049 witness_ddb_display_list(prnt, &w_spin); 1050 if (db_pager_quit) 1051 return; 1052 1053 /* 1054 * Finally, any locks which have not been acquired yet. 1055 */ 1056 prnt("\nLocks which were never acquired:\n"); 1057 STAILQ_FOREACH(w, &w_all, w_list) { 1058 if (w->w_file != NULL || w->w_refcount == 0) 1059 continue; 1060 prnt("%s (type: %s, depth: %d)\n", w->w_name, 1061 w->w_class->lc_name, w->w_ddb_level); 1062 if (db_pager_quit) 1063 return; 1064 } 1065 } 1066 #endif /* DDB */ 1067 1068 int 1069 witness_defineorder(struct lock_object *lock1, struct lock_object *lock2) 1070 { 1071 1072 if (witness_watch == -1 || panicstr != NULL) 1073 return (0); 1074 1075 /* Require locks that witness knows about. */ 1076 if (lock1 == NULL || lock1->lo_witness == NULL || lock2 == NULL || 1077 lock2->lo_witness == NULL) 1078 return (EINVAL); 1079 1080 mtx_assert(&w_mtx, MA_NOTOWNED); 1081 mtx_lock_spin(&w_mtx); 1082 1083 /* 1084 * If we already have either an explicit or implied lock order that 1085 * is the other way around, then return an error. 1086 */ 1087 if (witness_watch && 1088 isitmydescendant(lock2->lo_witness, lock1->lo_witness)) { 1089 mtx_unlock_spin(&w_mtx); 1090 return (EDOOFUS); 1091 } 1092 1093 /* Try to add the new order. */ 1094 CTR3(KTR_WITNESS, "%s: adding %s as a child of %s", __func__, 1095 lock2->lo_witness->w_name, lock1->lo_witness->w_name); 1096 itismychild(lock1->lo_witness, lock2->lo_witness); 1097 mtx_unlock_spin(&w_mtx); 1098 return (0); 1099 } 1100 1101 void 1102 witness_checkorder(struct lock_object *lock, int flags, const char *file, 1103 int line, struct lock_object *interlock) 1104 { 1105 struct lock_list_entry *lock_list, *lle; 1106 struct lock_instance *lock1, *lock2, *plock; 1107 struct lock_class *class, *iclass; 1108 struct witness *w, *w1; 1109 struct thread *td; 1110 int i, j; 1111 1112 if (witness_cold || witness_watch < 1 || lock->lo_witness == NULL || 1113 panicstr != NULL) 1114 return; 1115 1116 w = lock->lo_witness; 1117 class = LOCK_CLASS(lock); 1118 td = curthread; 1119 1120 if (class->lc_flags & LC_SLEEPLOCK) { 1121 1122 /* 1123 * Since spin locks include a critical section, this check 1124 * implicitly enforces a lock order of all sleep locks before 1125 * all spin locks. 1126 */ 1127 if (td->td_critnest != 0 && !kdb_active) 1128 kassert_panic("acquiring blockable sleep lock with " 1129 "spinlock or critical section held (%s) %s @ %s:%d", 1130 class->lc_name, lock->lo_name, 1131 fixup_filename(file), line); 1132 1133 /* 1134 * If this is the first lock acquired then just return as 1135 * no order checking is needed. 1136 */ 1137 lock_list = td->td_sleeplocks; 1138 if (lock_list == NULL || lock_list->ll_count == 0) 1139 return; 1140 } else { 1141 1142 /* 1143 * If this is the first lock, just return as no order 1144 * checking is needed. Avoid problems with thread 1145 * migration pinning the thread while checking if 1146 * spinlocks are held. If at least one spinlock is held 1147 * the thread is in a safe path and it is allowed to 1148 * unpin it. 1149 */ 1150 sched_pin(); 1151 lock_list = PCPU_GET(spinlocks); 1152 if (lock_list == NULL || lock_list->ll_count == 0) { 1153 sched_unpin(); 1154 return; 1155 } 1156 sched_unpin(); 1157 } 1158 1159 /* 1160 * Check to see if we are recursing on a lock we already own. If 1161 * so, make sure that we don't mismatch exclusive and shared lock 1162 * acquires. 1163 */ 1164 lock1 = find_instance(lock_list, lock); 1165 if (lock1 != NULL) { 1166 if ((lock1->li_flags & LI_EXCLUSIVE) != 0 && 1167 (flags & LOP_EXCLUSIVE) == 0) { 1168 witness_output("shared lock of (%s) %s @ %s:%d\n", 1169 class->lc_name, lock->lo_name, 1170 fixup_filename(file), line); 1171 witness_output("while exclusively locked from %s:%d\n", 1172 fixup_filename(lock1->li_file), lock1->li_line); 1173 kassert_panic("excl->share"); 1174 } 1175 if ((lock1->li_flags & LI_EXCLUSIVE) == 0 && 1176 (flags & LOP_EXCLUSIVE) != 0) { 1177 witness_output("exclusive lock of (%s) %s @ %s:%d\n", 1178 class->lc_name, lock->lo_name, 1179 fixup_filename(file), line); 1180 witness_output("while share locked from %s:%d\n", 1181 fixup_filename(lock1->li_file), lock1->li_line); 1182 kassert_panic("share->excl"); 1183 } 1184 return; 1185 } 1186 1187 /* Warn if the interlock is not locked exactly once. */ 1188 if (interlock != NULL) { 1189 iclass = LOCK_CLASS(interlock); 1190 lock1 = find_instance(lock_list, interlock); 1191 if (lock1 == NULL) 1192 kassert_panic("interlock (%s) %s not locked @ %s:%d", 1193 iclass->lc_name, interlock->lo_name, 1194 fixup_filename(file), line); 1195 else if ((lock1->li_flags & LI_RECURSEMASK) != 0) 1196 kassert_panic("interlock (%s) %s recursed @ %s:%d", 1197 iclass->lc_name, interlock->lo_name, 1198 fixup_filename(file), line); 1199 } 1200 1201 /* 1202 * Find the previously acquired lock, but ignore interlocks. 1203 */ 1204 plock = &lock_list->ll_children[lock_list->ll_count - 1]; 1205 if (interlock != NULL && plock->li_lock == interlock) { 1206 if (lock_list->ll_count > 1) 1207 plock = 1208 &lock_list->ll_children[lock_list->ll_count - 2]; 1209 else { 1210 lle = lock_list->ll_next; 1211 1212 /* 1213 * The interlock is the only lock we hold, so 1214 * simply return. 1215 */ 1216 if (lle == NULL) 1217 return; 1218 plock = &lle->ll_children[lle->ll_count - 1]; 1219 } 1220 } 1221 1222 /* 1223 * Try to perform most checks without a lock. If this succeeds we 1224 * can skip acquiring the lock and return success. Otherwise we redo 1225 * the check with the lock held to handle races with concurrent updates. 1226 */ 1227 w1 = plock->li_lock->lo_witness; 1228 if (witness_lock_order_check(w1, w)) 1229 return; 1230 1231 mtx_lock_spin(&w_mtx); 1232 if (witness_lock_order_check(w1, w)) { 1233 mtx_unlock_spin(&w_mtx); 1234 return; 1235 } 1236 witness_lock_order_add(w1, w); 1237 1238 /* 1239 * Check for duplicate locks of the same type. Note that we only 1240 * have to check for this on the last lock we just acquired. Any 1241 * other cases will be caught as lock order violations. 1242 */ 1243 if (w1 == w) { 1244 i = w->w_index; 1245 if (!(lock->lo_flags & LO_DUPOK) && !(flags & LOP_DUPOK) && 1246 !(w_rmatrix[i][i] & WITNESS_REVERSAL)) { 1247 w_rmatrix[i][i] |= WITNESS_REVERSAL; 1248 w->w_reversed = 1; 1249 mtx_unlock_spin(&w_mtx); 1250 witness_output( 1251 "acquiring duplicate lock of same type: \"%s\"\n", 1252 w->w_name); 1253 witness_output(" 1st %s @ %s:%d\n", plock->li_lock->lo_name, 1254 fixup_filename(plock->li_file), plock->li_line); 1255 witness_output(" 2nd %s @ %s:%d\n", lock->lo_name, 1256 fixup_filename(file), line); 1257 witness_debugger(1, __func__); 1258 } else 1259 mtx_unlock_spin(&w_mtx); 1260 return; 1261 } 1262 mtx_assert(&w_mtx, MA_OWNED); 1263 1264 /* 1265 * If we know that the lock we are acquiring comes after 1266 * the lock we most recently acquired in the lock order tree, 1267 * then there is no need for any further checks. 1268 */ 1269 if (isitmychild(w1, w)) 1270 goto out; 1271 1272 for (j = 0, lle = lock_list; lle != NULL; lle = lle->ll_next) { 1273 for (i = lle->ll_count - 1; i >= 0; i--, j++) { 1274 1275 MPASS(j < LOCK_CHILDCOUNT * LOCK_NCHILDREN); 1276 lock1 = &lle->ll_children[i]; 1277 1278 /* 1279 * Ignore the interlock. 1280 */ 1281 if (interlock == lock1->li_lock) 1282 continue; 1283 1284 /* 1285 * If this lock doesn't undergo witness checking, 1286 * then skip it. 1287 */ 1288 w1 = lock1->li_lock->lo_witness; 1289 if (w1 == NULL) { 1290 KASSERT((lock1->li_lock->lo_flags & LO_WITNESS) == 0, 1291 ("lock missing witness structure")); 1292 continue; 1293 } 1294 1295 /* 1296 * If we are locking Giant and this is a sleepable 1297 * lock, then skip it. 1298 */ 1299 if ((lock1->li_lock->lo_flags & LO_SLEEPABLE) != 0 && 1300 lock == &Giant.lock_object) 1301 continue; 1302 1303 /* 1304 * If we are locking a sleepable lock and this lock 1305 * is Giant, then skip it. 1306 */ 1307 if ((lock->lo_flags & LO_SLEEPABLE) != 0 && 1308 lock1->li_lock == &Giant.lock_object) 1309 continue; 1310 1311 /* 1312 * If we are locking a sleepable lock and this lock 1313 * isn't sleepable, we want to treat it as a lock 1314 * order violation to enfore a general lock order of 1315 * sleepable locks before non-sleepable locks. 1316 */ 1317 if (((lock->lo_flags & LO_SLEEPABLE) != 0 && 1318 (lock1->li_lock->lo_flags & LO_SLEEPABLE) == 0)) 1319 goto reversal; 1320 1321 /* 1322 * If we are locking Giant and this is a non-sleepable 1323 * lock, then treat it as a reversal. 1324 */ 1325 if ((lock1->li_lock->lo_flags & LO_SLEEPABLE) == 0 && 1326 lock == &Giant.lock_object) 1327 goto reversal; 1328 1329 /* 1330 * Check the lock order hierarchy for a reveresal. 1331 */ 1332 if (!isitmydescendant(w, w1)) 1333 continue; 1334 reversal: 1335 1336 /* 1337 * We have a lock order violation, check to see if it 1338 * is allowed or has already been yelled about. 1339 */ 1340 #ifdef BLESSING 1341 1342 /* 1343 * If the lock order is blessed, just bail. We don't 1344 * look for other lock order violations though, which 1345 * may be a bug. 1346 */ 1347 if (blessed(w, w1)) 1348 goto out; 1349 #endif 1350 1351 /* Bail if this violation is known */ 1352 if (w_rmatrix[w1->w_index][w->w_index] & WITNESS_REVERSAL) 1353 goto out; 1354 1355 /* Record this as a violation */ 1356 w_rmatrix[w1->w_index][w->w_index] |= WITNESS_REVERSAL; 1357 w_rmatrix[w->w_index][w1->w_index] |= WITNESS_REVERSAL; 1358 w->w_reversed = w1->w_reversed = 1; 1359 witness_increment_graph_generation(); 1360 mtx_unlock_spin(&w_mtx); 1361 1362 #ifdef WITNESS_NO_VNODE 1363 /* 1364 * There are known LORs between VNODE locks. They are 1365 * not an indication of a bug. VNODE locks are flagged 1366 * as such (LO_IS_VNODE) and we don't yell if the LOR 1367 * is between 2 VNODE locks. 1368 */ 1369 if ((lock->lo_flags & LO_IS_VNODE) != 0 && 1370 (lock1->li_lock->lo_flags & LO_IS_VNODE) != 0) 1371 return; 1372 #endif 1373 1374 /* 1375 * Ok, yell about it. 1376 */ 1377 if (((lock->lo_flags & LO_SLEEPABLE) != 0 && 1378 (lock1->li_lock->lo_flags & LO_SLEEPABLE) == 0)) 1379 witness_output( 1380 "lock order reversal: (sleepable after non-sleepable)\n"); 1381 else if ((lock1->li_lock->lo_flags & LO_SLEEPABLE) == 0 1382 && lock == &Giant.lock_object) 1383 witness_output( 1384 "lock order reversal: (Giant after non-sleepable)\n"); 1385 else 1386 witness_output("lock order reversal:\n"); 1387 1388 /* 1389 * Try to locate an earlier lock with 1390 * witness w in our list. 1391 */ 1392 do { 1393 lock2 = &lle->ll_children[i]; 1394 MPASS(lock2->li_lock != NULL); 1395 if (lock2->li_lock->lo_witness == w) 1396 break; 1397 if (i == 0 && lle->ll_next != NULL) { 1398 lle = lle->ll_next; 1399 i = lle->ll_count - 1; 1400 MPASS(i >= 0 && i < LOCK_NCHILDREN); 1401 } else 1402 i--; 1403 } while (i >= 0); 1404 if (i < 0) { 1405 witness_output(" 1st %p %s (%s) @ %s:%d\n", 1406 lock1->li_lock, lock1->li_lock->lo_name, 1407 w1->w_name, fixup_filename(lock1->li_file), 1408 lock1->li_line); 1409 witness_output(" 2nd %p %s (%s) @ %s:%d\n", lock, 1410 lock->lo_name, w->w_name, 1411 fixup_filename(file), line); 1412 } else { 1413 witness_output(" 1st %p %s (%s) @ %s:%d\n", 1414 lock2->li_lock, lock2->li_lock->lo_name, 1415 lock2->li_lock->lo_witness->w_name, 1416 fixup_filename(lock2->li_file), 1417 lock2->li_line); 1418 witness_output(" 2nd %p %s (%s) @ %s:%d\n", 1419 lock1->li_lock, lock1->li_lock->lo_name, 1420 w1->w_name, fixup_filename(lock1->li_file), 1421 lock1->li_line); 1422 witness_output(" 3rd %p %s (%s) @ %s:%d\n", lock, 1423 lock->lo_name, w->w_name, 1424 fixup_filename(file), line); 1425 } 1426 witness_debugger(1, __func__); 1427 return; 1428 } 1429 } 1430 1431 /* 1432 * If requested, build a new lock order. However, don't build a new 1433 * relationship between a sleepable lock and Giant if it is in the 1434 * wrong direction. The correct lock order is that sleepable locks 1435 * always come before Giant. 1436 */ 1437 if (flags & LOP_NEWORDER && 1438 !(plock->li_lock == &Giant.lock_object && 1439 (lock->lo_flags & LO_SLEEPABLE) != 0)) { 1440 CTR3(KTR_WITNESS, "%s: adding %s as a child of %s", __func__, 1441 w->w_name, plock->li_lock->lo_witness->w_name); 1442 itismychild(plock->li_lock->lo_witness, w); 1443 } 1444 out: 1445 mtx_unlock_spin(&w_mtx); 1446 } 1447 1448 void 1449 witness_lock(struct lock_object *lock, int flags, const char *file, int line) 1450 { 1451 struct lock_list_entry **lock_list, *lle; 1452 struct lock_instance *instance; 1453 struct witness *w; 1454 struct thread *td; 1455 1456 if (witness_cold || witness_watch == -1 || lock->lo_witness == NULL || 1457 panicstr != NULL) 1458 return; 1459 w = lock->lo_witness; 1460 td = curthread; 1461 1462 /* Determine lock list for this lock. */ 1463 if (LOCK_CLASS(lock)->lc_flags & LC_SLEEPLOCK) 1464 lock_list = &td->td_sleeplocks; 1465 else 1466 lock_list = PCPU_PTR(spinlocks); 1467 1468 /* Check to see if we are recursing on a lock we already own. */ 1469 instance = find_instance(*lock_list, lock); 1470 if (instance != NULL) { 1471 instance->li_flags++; 1472 CTR4(KTR_WITNESS, "%s: pid %d recursed on %s r=%d", __func__, 1473 td->td_proc->p_pid, lock->lo_name, 1474 instance->li_flags & LI_RECURSEMASK); 1475 instance->li_file = file; 1476 instance->li_line = line; 1477 return; 1478 } 1479 1480 /* Update per-witness last file and line acquire. */ 1481 w->w_file = file; 1482 w->w_line = line; 1483 1484 /* Find the next open lock instance in the list and fill it. */ 1485 lle = *lock_list; 1486 if (lle == NULL || lle->ll_count == LOCK_NCHILDREN) { 1487 lle = witness_lock_list_get(); 1488 if (lle == NULL) 1489 return; 1490 lle->ll_next = *lock_list; 1491 CTR3(KTR_WITNESS, "%s: pid %d added lle %p", __func__, 1492 td->td_proc->p_pid, lle); 1493 *lock_list = lle; 1494 } 1495 instance = &lle->ll_children[lle->ll_count++]; 1496 instance->li_lock = lock; 1497 instance->li_line = line; 1498 instance->li_file = file; 1499 if ((flags & LOP_EXCLUSIVE) != 0) 1500 instance->li_flags = LI_EXCLUSIVE; 1501 else 1502 instance->li_flags = 0; 1503 CTR4(KTR_WITNESS, "%s: pid %d added %s as lle[%d]", __func__, 1504 td->td_proc->p_pid, lock->lo_name, lle->ll_count - 1); 1505 } 1506 1507 void 1508 witness_upgrade(struct lock_object *lock, int flags, const char *file, int line) 1509 { 1510 struct lock_instance *instance; 1511 struct lock_class *class; 1512 1513 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); 1514 if (lock->lo_witness == NULL || witness_watch == -1 || panicstr != NULL) 1515 return; 1516 class = LOCK_CLASS(lock); 1517 if (witness_watch) { 1518 if ((lock->lo_flags & LO_UPGRADABLE) == 0) 1519 kassert_panic( 1520 "upgrade of non-upgradable lock (%s) %s @ %s:%d", 1521 class->lc_name, lock->lo_name, 1522 fixup_filename(file), line); 1523 if ((class->lc_flags & LC_SLEEPLOCK) == 0) 1524 kassert_panic( 1525 "upgrade of non-sleep lock (%s) %s @ %s:%d", 1526 class->lc_name, lock->lo_name, 1527 fixup_filename(file), line); 1528 } 1529 instance = find_instance(curthread->td_sleeplocks, lock); 1530 if (instance == NULL) { 1531 kassert_panic("upgrade of unlocked lock (%s) %s @ %s:%d", 1532 class->lc_name, lock->lo_name, 1533 fixup_filename(file), line); 1534 return; 1535 } 1536 if (witness_watch) { 1537 if ((instance->li_flags & LI_EXCLUSIVE) != 0) 1538 kassert_panic( 1539 "upgrade of exclusive lock (%s) %s @ %s:%d", 1540 class->lc_name, lock->lo_name, 1541 fixup_filename(file), line); 1542 if ((instance->li_flags & LI_RECURSEMASK) != 0) 1543 kassert_panic( 1544 "upgrade of recursed lock (%s) %s r=%d @ %s:%d", 1545 class->lc_name, lock->lo_name, 1546 instance->li_flags & LI_RECURSEMASK, 1547 fixup_filename(file), line); 1548 } 1549 instance->li_flags |= LI_EXCLUSIVE; 1550 } 1551 1552 void 1553 witness_downgrade(struct lock_object *lock, int flags, const char *file, 1554 int line) 1555 { 1556 struct lock_instance *instance; 1557 struct lock_class *class; 1558 1559 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); 1560 if (lock->lo_witness == NULL || witness_watch == -1 || panicstr != NULL) 1561 return; 1562 class = LOCK_CLASS(lock); 1563 if (witness_watch) { 1564 if ((lock->lo_flags & LO_UPGRADABLE) == 0) 1565 kassert_panic( 1566 "downgrade of non-upgradable lock (%s) %s @ %s:%d", 1567 class->lc_name, lock->lo_name, 1568 fixup_filename(file), line); 1569 if ((class->lc_flags & LC_SLEEPLOCK) == 0) 1570 kassert_panic( 1571 "downgrade of non-sleep lock (%s) %s @ %s:%d", 1572 class->lc_name, lock->lo_name, 1573 fixup_filename(file), line); 1574 } 1575 instance = find_instance(curthread->td_sleeplocks, lock); 1576 if (instance == NULL) { 1577 kassert_panic("downgrade of unlocked lock (%s) %s @ %s:%d", 1578 class->lc_name, lock->lo_name, 1579 fixup_filename(file), line); 1580 return; 1581 } 1582 if (witness_watch) { 1583 if ((instance->li_flags & LI_EXCLUSIVE) == 0) 1584 kassert_panic( 1585 "downgrade of shared lock (%s) %s @ %s:%d", 1586 class->lc_name, lock->lo_name, 1587 fixup_filename(file), line); 1588 if ((instance->li_flags & LI_RECURSEMASK) != 0) 1589 kassert_panic( 1590 "downgrade of recursed lock (%s) %s r=%d @ %s:%d", 1591 class->lc_name, lock->lo_name, 1592 instance->li_flags & LI_RECURSEMASK, 1593 fixup_filename(file), line); 1594 } 1595 instance->li_flags &= ~LI_EXCLUSIVE; 1596 } 1597 1598 void 1599 witness_unlock(struct lock_object *lock, int flags, const char *file, int line) 1600 { 1601 struct lock_list_entry **lock_list, *lle; 1602 struct lock_instance *instance; 1603 struct lock_class *class; 1604 struct thread *td; 1605 register_t s; 1606 int i, j; 1607 1608 if (witness_cold || lock->lo_witness == NULL || panicstr != NULL) 1609 return; 1610 td = curthread; 1611 class = LOCK_CLASS(lock); 1612 1613 /* Find lock instance associated with this lock. */ 1614 if (class->lc_flags & LC_SLEEPLOCK) 1615 lock_list = &td->td_sleeplocks; 1616 else 1617 lock_list = PCPU_PTR(spinlocks); 1618 lle = *lock_list; 1619 for (; *lock_list != NULL; lock_list = &(*lock_list)->ll_next) 1620 for (i = 0; i < (*lock_list)->ll_count; i++) { 1621 instance = &(*lock_list)->ll_children[i]; 1622 if (instance->li_lock == lock) 1623 goto found; 1624 } 1625 1626 /* 1627 * When disabling WITNESS through witness_watch we could end up in 1628 * having registered locks in the td_sleeplocks queue. 1629 * We have to make sure we flush these queues, so just search for 1630 * eventual register locks and remove them. 1631 */ 1632 if (witness_watch > 0) { 1633 kassert_panic("lock (%s) %s not locked @ %s:%d", class->lc_name, 1634 lock->lo_name, fixup_filename(file), line); 1635 return; 1636 } else { 1637 return; 1638 } 1639 found: 1640 1641 /* First, check for shared/exclusive mismatches. */ 1642 if ((instance->li_flags & LI_EXCLUSIVE) != 0 && witness_watch > 0 && 1643 (flags & LOP_EXCLUSIVE) == 0) { 1644 witness_output("shared unlock of (%s) %s @ %s:%d\n", 1645 class->lc_name, lock->lo_name, fixup_filename(file), line); 1646 witness_output("while exclusively locked from %s:%d\n", 1647 fixup_filename(instance->li_file), instance->li_line); 1648 kassert_panic("excl->ushare"); 1649 } 1650 if ((instance->li_flags & LI_EXCLUSIVE) == 0 && witness_watch > 0 && 1651 (flags & LOP_EXCLUSIVE) != 0) { 1652 witness_output("exclusive unlock of (%s) %s @ %s:%d\n", 1653 class->lc_name, lock->lo_name, fixup_filename(file), line); 1654 witness_output("while share locked from %s:%d\n", 1655 fixup_filename(instance->li_file), 1656 instance->li_line); 1657 kassert_panic("share->uexcl"); 1658 } 1659 /* If we are recursed, unrecurse. */ 1660 if ((instance->li_flags & LI_RECURSEMASK) > 0) { 1661 CTR4(KTR_WITNESS, "%s: pid %d unrecursed on %s r=%d", __func__, 1662 td->td_proc->p_pid, instance->li_lock->lo_name, 1663 instance->li_flags); 1664 instance->li_flags--; 1665 return; 1666 } 1667 /* The lock is now being dropped, check for NORELEASE flag */ 1668 if ((instance->li_flags & LI_NORELEASE) != 0 && witness_watch > 0) { 1669 witness_output("forbidden unlock of (%s) %s @ %s:%d\n", 1670 class->lc_name, lock->lo_name, fixup_filename(file), line); 1671 kassert_panic("lock marked norelease"); 1672 } 1673 1674 /* Otherwise, remove this item from the list. */ 1675 s = intr_disable(); 1676 CTR4(KTR_WITNESS, "%s: pid %d removed %s from lle[%d]", __func__, 1677 td->td_proc->p_pid, instance->li_lock->lo_name, 1678 (*lock_list)->ll_count - 1); 1679 for (j = i; j < (*lock_list)->ll_count - 1; j++) 1680 (*lock_list)->ll_children[j] = 1681 (*lock_list)->ll_children[j + 1]; 1682 (*lock_list)->ll_count--; 1683 intr_restore(s); 1684 1685 /* 1686 * In order to reduce contention on w_mtx, we want to keep always an 1687 * head object into lists so that frequent allocation from the 1688 * free witness pool (and subsequent locking) is avoided. 1689 * In order to maintain the current code simple, when the head 1690 * object is totally unloaded it means also that we do not have 1691 * further objects in the list, so the list ownership needs to be 1692 * hand over to another object if the current head needs to be freed. 1693 */ 1694 if ((*lock_list)->ll_count == 0) { 1695 if (*lock_list == lle) { 1696 if (lle->ll_next == NULL) 1697 return; 1698 } else 1699 lle = *lock_list; 1700 *lock_list = lle->ll_next; 1701 CTR3(KTR_WITNESS, "%s: pid %d removed lle %p", __func__, 1702 td->td_proc->p_pid, lle); 1703 witness_lock_list_free(lle); 1704 } 1705 } 1706 1707 void 1708 witness_thread_exit(struct thread *td) 1709 { 1710 struct lock_list_entry *lle; 1711 int i, n; 1712 1713 lle = td->td_sleeplocks; 1714 if (lle == NULL || panicstr != NULL) 1715 return; 1716 if (lle->ll_count != 0) { 1717 for (n = 0; lle != NULL; lle = lle->ll_next) 1718 for (i = lle->ll_count - 1; i >= 0; i--) { 1719 if (n == 0) 1720 witness_output( 1721 "Thread %p exiting with the following locks held:\n", td); 1722 n++; 1723 witness_list_lock(&lle->ll_children[i], 1724 witness_output); 1725 1726 } 1727 kassert_panic( 1728 "Thread %p cannot exit while holding sleeplocks\n", td); 1729 } 1730 witness_lock_list_free(lle); 1731 } 1732 1733 /* 1734 * Warn if any locks other than 'lock' are held. Flags can be passed in to 1735 * exempt Giant and sleepable locks from the checks as well. If any 1736 * non-exempt locks are held, then a supplied message is printed to the 1737 * output channel along with a list of the offending locks. If indicated in the 1738 * flags then a failure results in a panic as well. 1739 */ 1740 int 1741 witness_warn(int flags, struct lock_object *lock, const char *fmt, ...) 1742 { 1743 struct lock_list_entry *lock_list, *lle; 1744 struct lock_instance *lock1; 1745 struct thread *td; 1746 va_list ap; 1747 int i, n; 1748 1749 if (witness_cold || witness_watch < 1 || panicstr != NULL) 1750 return (0); 1751 n = 0; 1752 td = curthread; 1753 for (lle = td->td_sleeplocks; lle != NULL; lle = lle->ll_next) 1754 for (i = lle->ll_count - 1; i >= 0; i--) { 1755 lock1 = &lle->ll_children[i]; 1756 if (lock1->li_lock == lock) 1757 continue; 1758 if (flags & WARN_GIANTOK && 1759 lock1->li_lock == &Giant.lock_object) 1760 continue; 1761 if (flags & WARN_SLEEPOK && 1762 (lock1->li_lock->lo_flags & LO_SLEEPABLE) != 0) 1763 continue; 1764 if (n == 0) { 1765 va_start(ap, fmt); 1766 vprintf(fmt, ap); 1767 va_end(ap); 1768 printf(" with the following %slocks held:\n", 1769 (flags & WARN_SLEEPOK) != 0 ? 1770 "non-sleepable " : ""); 1771 } 1772 n++; 1773 witness_list_lock(lock1, printf); 1774 } 1775 1776 /* 1777 * Pin the thread in order to avoid problems with thread migration. 1778 * Once that all verifies are passed about spinlocks ownership, 1779 * the thread is in a safe path and it can be unpinned. 1780 */ 1781 sched_pin(); 1782 lock_list = PCPU_GET(spinlocks); 1783 if (lock_list != NULL && lock_list->ll_count != 0) { 1784 sched_unpin(); 1785 1786 /* 1787 * We should only have one spinlock and as long as 1788 * the flags cannot match for this locks class, 1789 * check if the first spinlock is the one curthread 1790 * should hold. 1791 */ 1792 lock1 = &lock_list->ll_children[lock_list->ll_count - 1]; 1793 if (lock_list->ll_count == 1 && lock_list->ll_next == NULL && 1794 lock1->li_lock == lock && n == 0) 1795 return (0); 1796 1797 va_start(ap, fmt); 1798 vprintf(fmt, ap); 1799 va_end(ap); 1800 printf(" with the following %slocks held:\n", 1801 (flags & WARN_SLEEPOK) != 0 ? "non-sleepable " : ""); 1802 n += witness_list_locks(&lock_list, printf); 1803 } else 1804 sched_unpin(); 1805 if (flags & WARN_PANIC && n) 1806 kassert_panic("%s", __func__); 1807 else 1808 witness_debugger(n, __func__); 1809 return (n); 1810 } 1811 1812 const char * 1813 witness_file(struct lock_object *lock) 1814 { 1815 struct witness *w; 1816 1817 if (witness_cold || witness_watch < 1 || lock->lo_witness == NULL) 1818 return ("?"); 1819 w = lock->lo_witness; 1820 return (w->w_file); 1821 } 1822 1823 int 1824 witness_line(struct lock_object *lock) 1825 { 1826 struct witness *w; 1827 1828 if (witness_cold || witness_watch < 1 || lock->lo_witness == NULL) 1829 return (0); 1830 w = lock->lo_witness; 1831 return (w->w_line); 1832 } 1833 1834 static struct witness * 1835 enroll(const char *description, struct lock_class *lock_class) 1836 { 1837 struct witness *w; 1838 1839 MPASS(description != NULL); 1840 1841 if (witness_watch == -1 || panicstr != NULL) 1842 return (NULL); 1843 if ((lock_class->lc_flags & LC_SPINLOCK)) { 1844 if (witness_skipspin) 1845 return (NULL); 1846 } else if ((lock_class->lc_flags & LC_SLEEPLOCK) == 0) { 1847 kassert_panic("lock class %s is not sleep or spin", 1848 lock_class->lc_name); 1849 return (NULL); 1850 } 1851 1852 mtx_lock_spin(&w_mtx); 1853 w = witness_hash_get(description); 1854 if (w) 1855 goto found; 1856 if ((w = witness_get()) == NULL) 1857 return (NULL); 1858 MPASS(strlen(description) < MAX_W_NAME); 1859 strcpy(w->w_name, description); 1860 w->w_class = lock_class; 1861 w->w_refcount = 1; 1862 STAILQ_INSERT_HEAD(&w_all, w, w_list); 1863 if (lock_class->lc_flags & LC_SPINLOCK) { 1864 STAILQ_INSERT_HEAD(&w_spin, w, w_typelist); 1865 w_spin_cnt++; 1866 } else if (lock_class->lc_flags & LC_SLEEPLOCK) { 1867 STAILQ_INSERT_HEAD(&w_sleep, w, w_typelist); 1868 w_sleep_cnt++; 1869 } 1870 1871 /* Insert new witness into the hash */ 1872 witness_hash_put(w); 1873 witness_increment_graph_generation(); 1874 mtx_unlock_spin(&w_mtx); 1875 return (w); 1876 found: 1877 w->w_refcount++; 1878 if (w->w_refcount == 1) 1879 w->w_class = lock_class; 1880 mtx_unlock_spin(&w_mtx); 1881 if (lock_class != w->w_class) 1882 kassert_panic( 1883 "lock (%s) %s does not match earlier (%s) lock", 1884 description, lock_class->lc_name, 1885 w->w_class->lc_name); 1886 return (w); 1887 } 1888 1889 static void 1890 depart(struct witness *w) 1891 { 1892 1893 MPASS(w->w_refcount == 0); 1894 if (w->w_class->lc_flags & LC_SLEEPLOCK) { 1895 w_sleep_cnt--; 1896 } else { 1897 w_spin_cnt--; 1898 } 1899 /* 1900 * Set file to NULL as it may point into a loadable module. 1901 */ 1902 w->w_file = NULL; 1903 w->w_line = 0; 1904 witness_increment_graph_generation(); 1905 } 1906 1907 1908 static void 1909 adopt(struct witness *parent, struct witness *child) 1910 { 1911 int pi, ci, i, j; 1912 1913 if (witness_cold == 0) 1914 mtx_assert(&w_mtx, MA_OWNED); 1915 1916 /* If the relationship is already known, there's no work to be done. */ 1917 if (isitmychild(parent, child)) 1918 return; 1919 1920 /* When the structure of the graph changes, bump up the generation. */ 1921 witness_increment_graph_generation(); 1922 1923 /* 1924 * The hard part ... create the direct relationship, then propagate all 1925 * indirect relationships. 1926 */ 1927 pi = parent->w_index; 1928 ci = child->w_index; 1929 WITNESS_INDEX_ASSERT(pi); 1930 WITNESS_INDEX_ASSERT(ci); 1931 MPASS(pi != ci); 1932 w_rmatrix[pi][ci] |= WITNESS_PARENT; 1933 w_rmatrix[ci][pi] |= WITNESS_CHILD; 1934 1935 /* 1936 * If parent was not already an ancestor of child, 1937 * then we increment the descendant and ancestor counters. 1938 */ 1939 if ((w_rmatrix[pi][ci] & WITNESS_ANCESTOR) == 0) { 1940 parent->w_num_descendants++; 1941 child->w_num_ancestors++; 1942 } 1943 1944 /* 1945 * Find each ancestor of 'pi'. Note that 'pi' itself is counted as 1946 * an ancestor of 'pi' during this loop. 1947 */ 1948 for (i = 1; i <= w_max_used_index; i++) { 1949 if ((w_rmatrix[i][pi] & WITNESS_ANCESTOR_MASK) == 0 && 1950 (i != pi)) 1951 continue; 1952 1953 /* Find each descendant of 'i' and mark it as a descendant. */ 1954 for (j = 1; j <= w_max_used_index; j++) { 1955 1956 /* 1957 * Skip children that are already marked as 1958 * descendants of 'i'. 1959 */ 1960 if (w_rmatrix[i][j] & WITNESS_ANCESTOR_MASK) 1961 continue; 1962 1963 /* 1964 * We are only interested in descendants of 'ci'. Note 1965 * that 'ci' itself is counted as a descendant of 'ci'. 1966 */ 1967 if ((w_rmatrix[ci][j] & WITNESS_ANCESTOR_MASK) == 0 && 1968 (j != ci)) 1969 continue; 1970 w_rmatrix[i][j] |= WITNESS_ANCESTOR; 1971 w_rmatrix[j][i] |= WITNESS_DESCENDANT; 1972 w_data[i].w_num_descendants++; 1973 w_data[j].w_num_ancestors++; 1974 1975 /* 1976 * Make sure we aren't marking a node as both an 1977 * ancestor and descendant. We should have caught 1978 * this as a lock order reversal earlier. 1979 */ 1980 if ((w_rmatrix[i][j] & WITNESS_ANCESTOR_MASK) && 1981 (w_rmatrix[i][j] & WITNESS_DESCENDANT_MASK)) { 1982 printf("witness rmatrix paradox! [%d][%d]=%d " 1983 "both ancestor and descendant\n", 1984 i, j, w_rmatrix[i][j]); 1985 kdb_backtrace(); 1986 printf("Witness disabled.\n"); 1987 witness_watch = -1; 1988 } 1989 if ((w_rmatrix[j][i] & WITNESS_ANCESTOR_MASK) && 1990 (w_rmatrix[j][i] & WITNESS_DESCENDANT_MASK)) { 1991 printf("witness rmatrix paradox! [%d][%d]=%d " 1992 "both ancestor and descendant\n", 1993 j, i, w_rmatrix[j][i]); 1994 kdb_backtrace(); 1995 printf("Witness disabled.\n"); 1996 witness_watch = -1; 1997 } 1998 } 1999 } 2000 } 2001 2002 static void 2003 itismychild(struct witness *parent, struct witness *child) 2004 { 2005 int unlocked; 2006 2007 MPASS(child != NULL && parent != NULL); 2008 if (witness_cold == 0) 2009 mtx_assert(&w_mtx, MA_OWNED); 2010 2011 if (!witness_lock_type_equal(parent, child)) { 2012 if (witness_cold == 0) { 2013 unlocked = 1; 2014 mtx_unlock_spin(&w_mtx); 2015 } else { 2016 unlocked = 0; 2017 } 2018 kassert_panic( 2019 "%s: parent \"%s\" (%s) and child \"%s\" (%s) are not " 2020 "the same lock type", __func__, parent->w_name, 2021 parent->w_class->lc_name, child->w_name, 2022 child->w_class->lc_name); 2023 if (unlocked) 2024 mtx_lock_spin(&w_mtx); 2025 } 2026 adopt(parent, child); 2027 } 2028 2029 /* 2030 * Generic code for the isitmy*() functions. The rmask parameter is the 2031 * expected relationship of w1 to w2. 2032 */ 2033 static int 2034 _isitmyx(struct witness *w1, struct witness *w2, int rmask, const char *fname) 2035 { 2036 unsigned char r1, r2; 2037 int i1, i2; 2038 2039 i1 = w1->w_index; 2040 i2 = w2->w_index; 2041 WITNESS_INDEX_ASSERT(i1); 2042 WITNESS_INDEX_ASSERT(i2); 2043 r1 = w_rmatrix[i1][i2] & WITNESS_RELATED_MASK; 2044 r2 = w_rmatrix[i2][i1] & WITNESS_RELATED_MASK; 2045 2046 /* The flags on one better be the inverse of the flags on the other */ 2047 if (!((WITNESS_ATOD(r1) == r2 && WITNESS_DTOA(r2) == r1) || 2048 (WITNESS_DTOA(r1) == r2 && WITNESS_ATOD(r2) == r1))) { 2049 /* Don't squawk if we're potentially racing with an update. */ 2050 if (!mtx_owned(&w_mtx)) 2051 return (0); 2052 printf("%s: rmatrix mismatch between %s (index %d) and %s " 2053 "(index %d): w_rmatrix[%d][%d] == %hhx but " 2054 "w_rmatrix[%d][%d] == %hhx\n", 2055 fname, w1->w_name, i1, w2->w_name, i2, i1, i2, r1, 2056 i2, i1, r2); 2057 kdb_backtrace(); 2058 printf("Witness disabled.\n"); 2059 witness_watch = -1; 2060 } 2061 return (r1 & rmask); 2062 } 2063 2064 /* 2065 * Checks if @child is a direct child of @parent. 2066 */ 2067 static int 2068 isitmychild(struct witness *parent, struct witness *child) 2069 { 2070 2071 return (_isitmyx(parent, child, WITNESS_PARENT, __func__)); 2072 } 2073 2074 /* 2075 * Checks if @descendant is a direct or inderect descendant of @ancestor. 2076 */ 2077 static int 2078 isitmydescendant(struct witness *ancestor, struct witness *descendant) 2079 { 2080 2081 return (_isitmyx(ancestor, descendant, WITNESS_ANCESTOR_MASK, 2082 __func__)); 2083 } 2084 2085 #ifdef BLESSING 2086 static int 2087 blessed(struct witness *w1, struct witness *w2) 2088 { 2089 int i; 2090 struct witness_blessed *b; 2091 2092 for (i = 0; i < nitems(blessed_list); i++) { 2093 b = &blessed_list[i]; 2094 if (strcmp(w1->w_name, b->b_lock1) == 0) { 2095 if (strcmp(w2->w_name, b->b_lock2) == 0) 2096 return (1); 2097 continue; 2098 } 2099 if (strcmp(w1->w_name, b->b_lock2) == 0) 2100 if (strcmp(w2->w_name, b->b_lock1) == 0) 2101 return (1); 2102 } 2103 return (0); 2104 } 2105 #endif 2106 2107 static struct witness * 2108 witness_get(void) 2109 { 2110 struct witness *w; 2111 int index; 2112 2113 if (witness_cold == 0) 2114 mtx_assert(&w_mtx, MA_OWNED); 2115 2116 if (witness_watch == -1) { 2117 mtx_unlock_spin(&w_mtx); 2118 return (NULL); 2119 } 2120 if (STAILQ_EMPTY(&w_free)) { 2121 witness_watch = -1; 2122 mtx_unlock_spin(&w_mtx); 2123 printf("WITNESS: unable to allocate a new witness object\n"); 2124 return (NULL); 2125 } 2126 w = STAILQ_FIRST(&w_free); 2127 STAILQ_REMOVE_HEAD(&w_free, w_list); 2128 w_free_cnt--; 2129 index = w->w_index; 2130 MPASS(index > 0 && index == w_max_used_index+1 && 2131 index < witness_count); 2132 bzero(w, sizeof(*w)); 2133 w->w_index = index; 2134 if (index > w_max_used_index) 2135 w_max_used_index = index; 2136 return (w); 2137 } 2138 2139 static void 2140 witness_free(struct witness *w) 2141 { 2142 2143 STAILQ_INSERT_HEAD(&w_free, w, w_list); 2144 w_free_cnt++; 2145 } 2146 2147 static struct lock_list_entry * 2148 witness_lock_list_get(void) 2149 { 2150 struct lock_list_entry *lle; 2151 2152 if (witness_watch == -1) 2153 return (NULL); 2154 mtx_lock_spin(&w_mtx); 2155 lle = w_lock_list_free; 2156 if (lle == NULL) { 2157 witness_watch = -1; 2158 mtx_unlock_spin(&w_mtx); 2159 printf("%s: witness exhausted\n", __func__); 2160 return (NULL); 2161 } 2162 w_lock_list_free = lle->ll_next; 2163 mtx_unlock_spin(&w_mtx); 2164 bzero(lle, sizeof(*lle)); 2165 return (lle); 2166 } 2167 2168 static void 2169 witness_lock_list_free(struct lock_list_entry *lle) 2170 { 2171 2172 mtx_lock_spin(&w_mtx); 2173 lle->ll_next = w_lock_list_free; 2174 w_lock_list_free = lle; 2175 mtx_unlock_spin(&w_mtx); 2176 } 2177 2178 static struct lock_instance * 2179 find_instance(struct lock_list_entry *list, const struct lock_object *lock) 2180 { 2181 struct lock_list_entry *lle; 2182 struct lock_instance *instance; 2183 int i; 2184 2185 for (lle = list; lle != NULL; lle = lle->ll_next) 2186 for (i = lle->ll_count - 1; i >= 0; i--) { 2187 instance = &lle->ll_children[i]; 2188 if (instance->li_lock == lock) 2189 return (instance); 2190 } 2191 return (NULL); 2192 } 2193 2194 static void 2195 witness_list_lock(struct lock_instance *instance, 2196 int (*prnt)(const char *fmt, ...)) 2197 { 2198 struct lock_object *lock; 2199 2200 lock = instance->li_lock; 2201 prnt("%s %s %s", (instance->li_flags & LI_EXCLUSIVE) != 0 ? 2202 "exclusive" : "shared", LOCK_CLASS(lock)->lc_name, lock->lo_name); 2203 if (lock->lo_witness->w_name != lock->lo_name) 2204 prnt(" (%s)", lock->lo_witness->w_name); 2205 prnt(" r = %d (%p) locked @ %s:%d\n", 2206 instance->li_flags & LI_RECURSEMASK, lock, 2207 fixup_filename(instance->li_file), instance->li_line); 2208 } 2209 2210 static int 2211 witness_output(const char *fmt, ...) 2212 { 2213 va_list ap; 2214 int ret; 2215 2216 va_start(ap, fmt); 2217 ret = witness_voutput(fmt, ap); 2218 va_end(ap); 2219 return (ret); 2220 } 2221 2222 static int 2223 witness_voutput(const char *fmt, va_list ap) 2224 { 2225 int ret; 2226 2227 ret = 0; 2228 switch (witness_channel) { 2229 case WITNESS_CONSOLE: 2230 ret = vprintf(fmt, ap); 2231 break; 2232 case WITNESS_LOG: 2233 vlog(LOG_NOTICE, fmt, ap); 2234 break; 2235 case WITNESS_NONE: 2236 break; 2237 } 2238 return (ret); 2239 } 2240 2241 #ifdef DDB 2242 static int 2243 witness_thread_has_locks(struct thread *td) 2244 { 2245 2246 if (td->td_sleeplocks == NULL) 2247 return (0); 2248 return (td->td_sleeplocks->ll_count != 0); 2249 } 2250 2251 static int 2252 witness_proc_has_locks(struct proc *p) 2253 { 2254 struct thread *td; 2255 2256 FOREACH_THREAD_IN_PROC(p, td) { 2257 if (witness_thread_has_locks(td)) 2258 return (1); 2259 } 2260 return (0); 2261 } 2262 #endif 2263 2264 int 2265 witness_list_locks(struct lock_list_entry **lock_list, 2266 int (*prnt)(const char *fmt, ...)) 2267 { 2268 struct lock_list_entry *lle; 2269 int i, nheld; 2270 2271 nheld = 0; 2272 for (lle = *lock_list; lle != NULL; lle = lle->ll_next) 2273 for (i = lle->ll_count - 1; i >= 0; i--) { 2274 witness_list_lock(&lle->ll_children[i], prnt); 2275 nheld++; 2276 } 2277 return (nheld); 2278 } 2279 2280 /* 2281 * This is a bit risky at best. We call this function when we have timed 2282 * out acquiring a spin lock, and we assume that the other CPU is stuck 2283 * with this lock held. So, we go groveling around in the other CPU's 2284 * per-cpu data to try to find the lock instance for this spin lock to 2285 * see when it was last acquired. 2286 */ 2287 void 2288 witness_display_spinlock(struct lock_object *lock, struct thread *owner, 2289 int (*prnt)(const char *fmt, ...)) 2290 { 2291 struct lock_instance *instance; 2292 struct pcpu *pc; 2293 2294 if (owner->td_critnest == 0 || owner->td_oncpu == NOCPU) 2295 return; 2296 pc = pcpu_find(owner->td_oncpu); 2297 instance = find_instance(pc->pc_spinlocks, lock); 2298 if (instance != NULL) 2299 witness_list_lock(instance, prnt); 2300 } 2301 2302 void 2303 witness_save(struct lock_object *lock, const char **filep, int *linep) 2304 { 2305 struct lock_list_entry *lock_list; 2306 struct lock_instance *instance; 2307 struct lock_class *class; 2308 2309 /* 2310 * This function is used independently in locking code to deal with 2311 * Giant, SCHEDULER_STOPPED() check can be removed here after Giant 2312 * is gone. 2313 */ 2314 if (SCHEDULER_STOPPED()) 2315 return; 2316 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); 2317 if (lock->lo_witness == NULL || witness_watch == -1 || panicstr != NULL) 2318 return; 2319 class = LOCK_CLASS(lock); 2320 if (class->lc_flags & LC_SLEEPLOCK) 2321 lock_list = curthread->td_sleeplocks; 2322 else { 2323 if (witness_skipspin) 2324 return; 2325 lock_list = PCPU_GET(spinlocks); 2326 } 2327 instance = find_instance(lock_list, lock); 2328 if (instance == NULL) { 2329 kassert_panic("%s: lock (%s) %s not locked", __func__, 2330 class->lc_name, lock->lo_name); 2331 return; 2332 } 2333 *filep = instance->li_file; 2334 *linep = instance->li_line; 2335 } 2336 2337 void 2338 witness_restore(struct lock_object *lock, const char *file, int line) 2339 { 2340 struct lock_list_entry *lock_list; 2341 struct lock_instance *instance; 2342 struct lock_class *class; 2343 2344 /* 2345 * This function is used independently in locking code to deal with 2346 * Giant, SCHEDULER_STOPPED() check can be removed here after Giant 2347 * is gone. 2348 */ 2349 if (SCHEDULER_STOPPED()) 2350 return; 2351 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); 2352 if (lock->lo_witness == NULL || witness_watch == -1 || panicstr != NULL) 2353 return; 2354 class = LOCK_CLASS(lock); 2355 if (class->lc_flags & LC_SLEEPLOCK) 2356 lock_list = curthread->td_sleeplocks; 2357 else { 2358 if (witness_skipspin) 2359 return; 2360 lock_list = PCPU_GET(spinlocks); 2361 } 2362 instance = find_instance(lock_list, lock); 2363 if (instance == NULL) 2364 kassert_panic("%s: lock (%s) %s not locked", __func__, 2365 class->lc_name, lock->lo_name); 2366 lock->lo_witness->w_file = file; 2367 lock->lo_witness->w_line = line; 2368 if (instance == NULL) 2369 return; 2370 instance->li_file = file; 2371 instance->li_line = line; 2372 } 2373 2374 void 2375 witness_assert(const struct lock_object *lock, int flags, const char *file, 2376 int line) 2377 { 2378 #ifdef INVARIANT_SUPPORT 2379 struct lock_instance *instance; 2380 struct lock_class *class; 2381 2382 if (lock->lo_witness == NULL || witness_watch < 1 || panicstr != NULL) 2383 return; 2384 class = LOCK_CLASS(lock); 2385 if ((class->lc_flags & LC_SLEEPLOCK) != 0) 2386 instance = find_instance(curthread->td_sleeplocks, lock); 2387 else if ((class->lc_flags & LC_SPINLOCK) != 0) 2388 instance = find_instance(PCPU_GET(spinlocks), lock); 2389 else { 2390 kassert_panic("Lock (%s) %s is not sleep or spin!", 2391 class->lc_name, lock->lo_name); 2392 return; 2393 } 2394 switch (flags) { 2395 case LA_UNLOCKED: 2396 if (instance != NULL) 2397 kassert_panic("Lock (%s) %s locked @ %s:%d.", 2398 class->lc_name, lock->lo_name, 2399 fixup_filename(file), line); 2400 break; 2401 case LA_LOCKED: 2402 case LA_LOCKED | LA_RECURSED: 2403 case LA_LOCKED | LA_NOTRECURSED: 2404 case LA_SLOCKED: 2405 case LA_SLOCKED | LA_RECURSED: 2406 case LA_SLOCKED | LA_NOTRECURSED: 2407 case LA_XLOCKED: 2408 case LA_XLOCKED | LA_RECURSED: 2409 case LA_XLOCKED | LA_NOTRECURSED: 2410 if (instance == NULL) { 2411 kassert_panic("Lock (%s) %s not locked @ %s:%d.", 2412 class->lc_name, lock->lo_name, 2413 fixup_filename(file), line); 2414 break; 2415 } 2416 if ((flags & LA_XLOCKED) != 0 && 2417 (instance->li_flags & LI_EXCLUSIVE) == 0) 2418 kassert_panic( 2419 "Lock (%s) %s not exclusively locked @ %s:%d.", 2420 class->lc_name, lock->lo_name, 2421 fixup_filename(file), line); 2422 if ((flags & LA_SLOCKED) != 0 && 2423 (instance->li_flags & LI_EXCLUSIVE) != 0) 2424 kassert_panic( 2425 "Lock (%s) %s exclusively locked @ %s:%d.", 2426 class->lc_name, lock->lo_name, 2427 fixup_filename(file), line); 2428 if ((flags & LA_RECURSED) != 0 && 2429 (instance->li_flags & LI_RECURSEMASK) == 0) 2430 kassert_panic("Lock (%s) %s not recursed @ %s:%d.", 2431 class->lc_name, lock->lo_name, 2432 fixup_filename(file), line); 2433 if ((flags & LA_NOTRECURSED) != 0 && 2434 (instance->li_flags & LI_RECURSEMASK) != 0) 2435 kassert_panic("Lock (%s) %s recursed @ %s:%d.", 2436 class->lc_name, lock->lo_name, 2437 fixup_filename(file), line); 2438 break; 2439 default: 2440 kassert_panic("Invalid lock assertion at %s:%d.", 2441 fixup_filename(file), line); 2442 2443 } 2444 #endif /* INVARIANT_SUPPORT */ 2445 } 2446 2447 static void 2448 witness_setflag(struct lock_object *lock, int flag, int set) 2449 { 2450 struct lock_list_entry *lock_list; 2451 struct lock_instance *instance; 2452 struct lock_class *class; 2453 2454 if (lock->lo_witness == NULL || witness_watch == -1 || panicstr != NULL) 2455 return; 2456 class = LOCK_CLASS(lock); 2457 if (class->lc_flags & LC_SLEEPLOCK) 2458 lock_list = curthread->td_sleeplocks; 2459 else { 2460 if (witness_skipspin) 2461 return; 2462 lock_list = PCPU_GET(spinlocks); 2463 } 2464 instance = find_instance(lock_list, lock); 2465 if (instance == NULL) { 2466 kassert_panic("%s: lock (%s) %s not locked", __func__, 2467 class->lc_name, lock->lo_name); 2468 return; 2469 } 2470 2471 if (set) 2472 instance->li_flags |= flag; 2473 else 2474 instance->li_flags &= ~flag; 2475 } 2476 2477 void 2478 witness_norelease(struct lock_object *lock) 2479 { 2480 2481 witness_setflag(lock, LI_NORELEASE, 1); 2482 } 2483 2484 void 2485 witness_releaseok(struct lock_object *lock) 2486 { 2487 2488 witness_setflag(lock, LI_NORELEASE, 0); 2489 } 2490 2491 #ifdef DDB 2492 static void 2493 witness_ddb_list(struct thread *td) 2494 { 2495 2496 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); 2497 KASSERT(kdb_active, ("%s: not in the debugger", __func__)); 2498 2499 if (witness_watch < 1) 2500 return; 2501 2502 witness_list_locks(&td->td_sleeplocks, db_printf); 2503 2504 /* 2505 * We only handle spinlocks if td == curthread. This is somewhat broken 2506 * if td is currently executing on some other CPU and holds spin locks 2507 * as we won't display those locks. If we had a MI way of getting 2508 * the per-cpu data for a given cpu then we could use 2509 * td->td_oncpu to get the list of spinlocks for this thread 2510 * and "fix" this. 2511 * 2512 * That still wouldn't really fix this unless we locked the scheduler 2513 * lock or stopped the other CPU to make sure it wasn't changing the 2514 * list out from under us. It is probably best to just not try to 2515 * handle threads on other CPU's for now. 2516 */ 2517 if (td == curthread && PCPU_GET(spinlocks) != NULL) 2518 witness_list_locks(PCPU_PTR(spinlocks), db_printf); 2519 } 2520 2521 DB_SHOW_COMMAND(locks, db_witness_list) 2522 { 2523 struct thread *td; 2524 2525 if (have_addr) 2526 td = db_lookup_thread(addr, true); 2527 else 2528 td = kdb_thread; 2529 witness_ddb_list(td); 2530 } 2531 2532 DB_SHOW_ALL_COMMAND(locks, db_witness_list_all) 2533 { 2534 struct thread *td; 2535 struct proc *p; 2536 2537 /* 2538 * It would be nice to list only threads and processes that actually 2539 * held sleep locks, but that information is currently not exported 2540 * by WITNESS. 2541 */ 2542 FOREACH_PROC_IN_SYSTEM(p) { 2543 if (!witness_proc_has_locks(p)) 2544 continue; 2545 FOREACH_THREAD_IN_PROC(p, td) { 2546 if (!witness_thread_has_locks(td)) 2547 continue; 2548 db_printf("Process %d (%s) thread %p (%d)\n", p->p_pid, 2549 p->p_comm, td, td->td_tid); 2550 witness_ddb_list(td); 2551 if (db_pager_quit) 2552 return; 2553 } 2554 } 2555 } 2556 DB_SHOW_ALIAS(alllocks, db_witness_list_all) 2557 2558 DB_SHOW_COMMAND(witness, db_witness_display) 2559 { 2560 2561 witness_ddb_display(db_printf); 2562 } 2563 #endif 2564 2565 static void 2566 sbuf_print_witness_badstacks(struct sbuf *sb, size_t *oldidx) 2567 { 2568 struct witness_lock_order_data *data1, *data2, *tmp_data1, *tmp_data2; 2569 struct witness *tmp_w1, *tmp_w2, *w1, *w2; 2570 int generation, i, j; 2571 2572 tmp_data1 = NULL; 2573 tmp_data2 = NULL; 2574 tmp_w1 = NULL; 2575 tmp_w2 = NULL; 2576 2577 /* Allocate and init temporary storage space. */ 2578 tmp_w1 = malloc(sizeof(struct witness), M_TEMP, M_WAITOK | M_ZERO); 2579 tmp_w2 = malloc(sizeof(struct witness), M_TEMP, M_WAITOK | M_ZERO); 2580 tmp_data1 = malloc(sizeof(struct witness_lock_order_data), M_TEMP, 2581 M_WAITOK | M_ZERO); 2582 tmp_data2 = malloc(sizeof(struct witness_lock_order_data), M_TEMP, 2583 M_WAITOK | M_ZERO); 2584 stack_zero(&tmp_data1->wlod_stack); 2585 stack_zero(&tmp_data2->wlod_stack); 2586 2587 restart: 2588 mtx_lock_spin(&w_mtx); 2589 generation = w_generation; 2590 mtx_unlock_spin(&w_mtx); 2591 sbuf_printf(sb, "Number of known direct relationships is %d\n", 2592 w_lohash.wloh_count); 2593 for (i = 1; i < w_max_used_index; i++) { 2594 mtx_lock_spin(&w_mtx); 2595 if (generation != w_generation) { 2596 mtx_unlock_spin(&w_mtx); 2597 2598 /* The graph has changed, try again. */ 2599 *oldidx = 0; 2600 sbuf_clear(sb); 2601 goto restart; 2602 } 2603 2604 w1 = &w_data[i]; 2605 if (w1->w_reversed == 0) { 2606 mtx_unlock_spin(&w_mtx); 2607 continue; 2608 } 2609 2610 /* Copy w1 locally so we can release the spin lock. */ 2611 *tmp_w1 = *w1; 2612 mtx_unlock_spin(&w_mtx); 2613 2614 if (tmp_w1->w_reversed == 0) 2615 continue; 2616 for (j = 1; j < w_max_used_index; j++) { 2617 if ((w_rmatrix[i][j] & WITNESS_REVERSAL) == 0 || i > j) 2618 continue; 2619 2620 mtx_lock_spin(&w_mtx); 2621 if (generation != w_generation) { 2622 mtx_unlock_spin(&w_mtx); 2623 2624 /* The graph has changed, try again. */ 2625 *oldidx = 0; 2626 sbuf_clear(sb); 2627 goto restart; 2628 } 2629 2630 w2 = &w_data[j]; 2631 data1 = witness_lock_order_get(w1, w2); 2632 data2 = witness_lock_order_get(w2, w1); 2633 2634 /* 2635 * Copy information locally so we can release the 2636 * spin lock. 2637 */ 2638 *tmp_w2 = *w2; 2639 2640 if (data1) { 2641 stack_zero(&tmp_data1->wlod_stack); 2642 stack_copy(&data1->wlod_stack, 2643 &tmp_data1->wlod_stack); 2644 } 2645 if (data2 && data2 != data1) { 2646 stack_zero(&tmp_data2->wlod_stack); 2647 stack_copy(&data2->wlod_stack, 2648 &tmp_data2->wlod_stack); 2649 } 2650 mtx_unlock_spin(&w_mtx); 2651 2652 sbuf_printf(sb, 2653 "\nLock order reversal between \"%s\"(%s) and \"%s\"(%s)!\n", 2654 tmp_w1->w_name, tmp_w1->w_class->lc_name, 2655 tmp_w2->w_name, tmp_w2->w_class->lc_name); 2656 if (data1) { 2657 sbuf_printf(sb, 2658 "Lock order \"%s\"(%s) -> \"%s\"(%s) first seen at:\n", 2659 tmp_w1->w_name, tmp_w1->w_class->lc_name, 2660 tmp_w2->w_name, tmp_w2->w_class->lc_name); 2661 stack_sbuf_print(sb, &tmp_data1->wlod_stack); 2662 sbuf_printf(sb, "\n"); 2663 } 2664 if (data2 && data2 != data1) { 2665 sbuf_printf(sb, 2666 "Lock order \"%s\"(%s) -> \"%s\"(%s) first seen at:\n", 2667 tmp_w2->w_name, tmp_w2->w_class->lc_name, 2668 tmp_w1->w_name, tmp_w1->w_class->lc_name); 2669 stack_sbuf_print(sb, &tmp_data2->wlod_stack); 2670 sbuf_printf(sb, "\n"); 2671 } 2672 } 2673 } 2674 mtx_lock_spin(&w_mtx); 2675 if (generation != w_generation) { 2676 mtx_unlock_spin(&w_mtx); 2677 2678 /* 2679 * The graph changed while we were printing stack data, 2680 * try again. 2681 */ 2682 *oldidx = 0; 2683 sbuf_clear(sb); 2684 goto restart; 2685 } 2686 mtx_unlock_spin(&w_mtx); 2687 2688 /* Free temporary storage space. */ 2689 free(tmp_data1, M_TEMP); 2690 free(tmp_data2, M_TEMP); 2691 free(tmp_w1, M_TEMP); 2692 free(tmp_w2, M_TEMP); 2693 } 2694 2695 static int 2696 sysctl_debug_witness_badstacks(SYSCTL_HANDLER_ARGS) 2697 { 2698 struct sbuf *sb; 2699 int error; 2700 2701 if (witness_watch < 1) { 2702 error = SYSCTL_OUT(req, w_notrunning, sizeof(w_notrunning)); 2703 return (error); 2704 } 2705 if (witness_cold) { 2706 error = SYSCTL_OUT(req, w_stillcold, sizeof(w_stillcold)); 2707 return (error); 2708 } 2709 error = 0; 2710 sb = sbuf_new(NULL, NULL, badstack_sbuf_size, SBUF_AUTOEXTEND); 2711 if (sb == NULL) 2712 return (ENOMEM); 2713 2714 sbuf_print_witness_badstacks(sb, &req->oldidx); 2715 2716 sbuf_finish(sb); 2717 error = SYSCTL_OUT(req, sbuf_data(sb), sbuf_len(sb) + 1); 2718 sbuf_delete(sb); 2719 2720 return (error); 2721 } 2722 2723 #ifdef DDB 2724 static int 2725 sbuf_db_printf_drain(void *arg __unused, const char *data, int len) 2726 { 2727 2728 return (db_printf("%.*s", len, data)); 2729 } 2730 2731 DB_SHOW_COMMAND(badstacks, db_witness_badstacks) 2732 { 2733 struct sbuf sb; 2734 char buffer[128]; 2735 size_t dummy; 2736 2737 sbuf_new(&sb, buffer, sizeof(buffer), SBUF_FIXEDLEN); 2738 sbuf_set_drain(&sb, sbuf_db_printf_drain, NULL); 2739 sbuf_print_witness_badstacks(&sb, &dummy); 2740 sbuf_finish(&sb); 2741 } 2742 #endif 2743 2744 static int 2745 sysctl_debug_witness_channel(SYSCTL_HANDLER_ARGS) 2746 { 2747 static const struct { 2748 enum witness_channel channel; 2749 const char *name; 2750 } channels[] = { 2751 { WITNESS_CONSOLE, "console" }, 2752 { WITNESS_LOG, "log" }, 2753 { WITNESS_NONE, "none" }, 2754 }; 2755 char buf[16]; 2756 u_int i; 2757 int error; 2758 2759 buf[0] = '\0'; 2760 for (i = 0; i < nitems(channels); i++) 2761 if (witness_channel == channels[i].channel) { 2762 snprintf(buf, sizeof(buf), "%s", channels[i].name); 2763 break; 2764 } 2765 2766 error = sysctl_handle_string(oidp, buf, sizeof(buf), req); 2767 if (error != 0 || req->newptr == NULL) 2768 return (error); 2769 2770 error = EINVAL; 2771 for (i = 0; i < nitems(channels); i++) 2772 if (strcmp(channels[i].name, buf) == 0) { 2773 witness_channel = channels[i].channel; 2774 error = 0; 2775 break; 2776 } 2777 return (error); 2778 } 2779 2780 static int 2781 sysctl_debug_witness_fullgraph(SYSCTL_HANDLER_ARGS) 2782 { 2783 struct witness *w; 2784 struct sbuf *sb; 2785 int error; 2786 2787 #ifdef __i386__ 2788 error = SYSCTL_OUT(req, w_notallowed, sizeof(w_notallowed)); 2789 return (error); 2790 #endif 2791 2792 if (witness_watch < 1) { 2793 error = SYSCTL_OUT(req, w_notrunning, sizeof(w_notrunning)); 2794 return (error); 2795 } 2796 if (witness_cold) { 2797 error = SYSCTL_OUT(req, w_stillcold, sizeof(w_stillcold)); 2798 return (error); 2799 } 2800 error = 0; 2801 2802 error = sysctl_wire_old_buffer(req, 0); 2803 if (error != 0) 2804 return (error); 2805 sb = sbuf_new_for_sysctl(NULL, NULL, FULLGRAPH_SBUF_SIZE, req); 2806 if (sb == NULL) 2807 return (ENOMEM); 2808 sbuf_printf(sb, "\n"); 2809 2810 mtx_lock_spin(&w_mtx); 2811 STAILQ_FOREACH(w, &w_all, w_list) 2812 w->w_displayed = 0; 2813 STAILQ_FOREACH(w, &w_all, w_list) 2814 witness_add_fullgraph(sb, w); 2815 mtx_unlock_spin(&w_mtx); 2816 2817 /* 2818 * Close the sbuf and return to userland. 2819 */ 2820 error = sbuf_finish(sb); 2821 sbuf_delete(sb); 2822 2823 return (error); 2824 } 2825 2826 static int 2827 sysctl_debug_witness_watch(SYSCTL_HANDLER_ARGS) 2828 { 2829 int error, value; 2830 2831 value = witness_watch; 2832 error = sysctl_handle_int(oidp, &value, 0, req); 2833 if (error != 0 || req->newptr == NULL) 2834 return (error); 2835 if (value > 1 || value < -1 || 2836 (witness_watch == -1 && value != witness_watch)) 2837 return (EINVAL); 2838 witness_watch = value; 2839 return (0); 2840 } 2841 2842 static void 2843 witness_add_fullgraph(struct sbuf *sb, struct witness *w) 2844 { 2845 int i; 2846 2847 if (w->w_displayed != 0 || (w->w_file == NULL && w->w_line == 0)) 2848 return; 2849 w->w_displayed = 1; 2850 2851 WITNESS_INDEX_ASSERT(w->w_index); 2852 for (i = 1; i <= w_max_used_index; i++) { 2853 if (w_rmatrix[w->w_index][i] & WITNESS_PARENT) { 2854 sbuf_printf(sb, "\"%s\",\"%s\"\n", w->w_name, 2855 w_data[i].w_name); 2856 witness_add_fullgraph(sb, &w_data[i]); 2857 } 2858 } 2859 } 2860 2861 /* 2862 * A simple hash function. Takes a key pointer and a key size. If size == 0, 2863 * interprets the key as a string and reads until the null 2864 * terminator. Otherwise, reads the first size bytes. Returns an unsigned 32-bit 2865 * hash value computed from the key. 2866 */ 2867 static uint32_t 2868 witness_hash_djb2(const uint8_t *key, uint32_t size) 2869 { 2870 unsigned int hash = 5381; 2871 int i; 2872 2873 /* hash = hash * 33 + key[i] */ 2874 if (size) 2875 for (i = 0; i < size; i++) 2876 hash = ((hash << 5) + hash) + (unsigned int)key[i]; 2877 else 2878 for (i = 0; key[i] != 0; i++) 2879 hash = ((hash << 5) + hash) + (unsigned int)key[i]; 2880 2881 return (hash); 2882 } 2883 2884 2885 /* 2886 * Initializes the two witness hash tables. Called exactly once from 2887 * witness_initialize(). 2888 */ 2889 static void 2890 witness_init_hash_tables(void) 2891 { 2892 int i; 2893 2894 MPASS(witness_cold); 2895 2896 /* Initialize the hash tables. */ 2897 for (i = 0; i < WITNESS_HASH_SIZE; i++) 2898 w_hash.wh_array[i] = NULL; 2899 2900 w_hash.wh_size = WITNESS_HASH_SIZE; 2901 w_hash.wh_count = 0; 2902 2903 /* Initialize the lock order data hash. */ 2904 w_lofree = NULL; 2905 for (i = 0; i < WITNESS_LO_DATA_COUNT; i++) { 2906 memset(&w_lodata[i], 0, sizeof(w_lodata[i])); 2907 w_lodata[i].wlod_next = w_lofree; 2908 w_lofree = &w_lodata[i]; 2909 } 2910 w_lohash.wloh_size = WITNESS_LO_HASH_SIZE; 2911 w_lohash.wloh_count = 0; 2912 for (i = 0; i < WITNESS_LO_HASH_SIZE; i++) 2913 w_lohash.wloh_array[i] = NULL; 2914 } 2915 2916 static struct witness * 2917 witness_hash_get(const char *key) 2918 { 2919 struct witness *w; 2920 uint32_t hash; 2921 2922 MPASS(key != NULL); 2923 if (witness_cold == 0) 2924 mtx_assert(&w_mtx, MA_OWNED); 2925 hash = witness_hash_djb2(key, 0) % w_hash.wh_size; 2926 w = w_hash.wh_array[hash]; 2927 while (w != NULL) { 2928 if (strcmp(w->w_name, key) == 0) 2929 goto out; 2930 w = w->w_hash_next; 2931 } 2932 2933 out: 2934 return (w); 2935 } 2936 2937 static void 2938 witness_hash_put(struct witness *w) 2939 { 2940 uint32_t hash; 2941 2942 MPASS(w != NULL); 2943 MPASS(w->w_name != NULL); 2944 if (witness_cold == 0) 2945 mtx_assert(&w_mtx, MA_OWNED); 2946 KASSERT(witness_hash_get(w->w_name) == NULL, 2947 ("%s: trying to add a hash entry that already exists!", __func__)); 2948 KASSERT(w->w_hash_next == NULL, 2949 ("%s: w->w_hash_next != NULL", __func__)); 2950 2951 hash = witness_hash_djb2(w->w_name, 0) % w_hash.wh_size; 2952 w->w_hash_next = w_hash.wh_array[hash]; 2953 w_hash.wh_array[hash] = w; 2954 w_hash.wh_count++; 2955 } 2956 2957 2958 static struct witness_lock_order_data * 2959 witness_lock_order_get(struct witness *parent, struct witness *child) 2960 { 2961 struct witness_lock_order_data *data = NULL; 2962 struct witness_lock_order_key key; 2963 unsigned int hash; 2964 2965 MPASS(parent != NULL && child != NULL); 2966 key.from = parent->w_index; 2967 key.to = child->w_index; 2968 WITNESS_INDEX_ASSERT(key.from); 2969 WITNESS_INDEX_ASSERT(key.to); 2970 if ((w_rmatrix[parent->w_index][child->w_index] 2971 & WITNESS_LOCK_ORDER_KNOWN) == 0) 2972 goto out; 2973 2974 hash = witness_hash_djb2((const char*)&key, 2975 sizeof(key)) % w_lohash.wloh_size; 2976 data = w_lohash.wloh_array[hash]; 2977 while (data != NULL) { 2978 if (witness_lock_order_key_equal(&data->wlod_key, &key)) 2979 break; 2980 data = data->wlod_next; 2981 } 2982 2983 out: 2984 return (data); 2985 } 2986 2987 /* 2988 * Verify that parent and child have a known relationship, are not the same, 2989 * and child is actually a child of parent. This is done without w_mtx 2990 * to avoid contention in the common case. 2991 */ 2992 static int 2993 witness_lock_order_check(struct witness *parent, struct witness *child) 2994 { 2995 2996 if (parent != child && 2997 w_rmatrix[parent->w_index][child->w_index] 2998 & WITNESS_LOCK_ORDER_KNOWN && 2999 isitmychild(parent, child)) 3000 return (1); 3001 3002 return (0); 3003 } 3004 3005 static int 3006 witness_lock_order_add(struct witness *parent, struct witness *child) 3007 { 3008 struct witness_lock_order_data *data = NULL; 3009 struct witness_lock_order_key key; 3010 unsigned int hash; 3011 3012 MPASS(parent != NULL && child != NULL); 3013 key.from = parent->w_index; 3014 key.to = child->w_index; 3015 WITNESS_INDEX_ASSERT(key.from); 3016 WITNESS_INDEX_ASSERT(key.to); 3017 if (w_rmatrix[parent->w_index][child->w_index] 3018 & WITNESS_LOCK_ORDER_KNOWN) 3019 return (1); 3020 3021 hash = witness_hash_djb2((const char*)&key, 3022 sizeof(key)) % w_lohash.wloh_size; 3023 w_rmatrix[parent->w_index][child->w_index] |= WITNESS_LOCK_ORDER_KNOWN; 3024 data = w_lofree; 3025 if (data == NULL) 3026 return (0); 3027 w_lofree = data->wlod_next; 3028 data->wlod_next = w_lohash.wloh_array[hash]; 3029 data->wlod_key = key; 3030 w_lohash.wloh_array[hash] = data; 3031 w_lohash.wloh_count++; 3032 stack_zero(&data->wlod_stack); 3033 stack_save(&data->wlod_stack); 3034 return (1); 3035 } 3036 3037 /* Call this whenever the structure of the witness graph changes. */ 3038 static void 3039 witness_increment_graph_generation(void) 3040 { 3041 3042 if (witness_cold == 0) 3043 mtx_assert(&w_mtx, MA_OWNED); 3044 w_generation++; 3045 } 3046 3047 static int 3048 witness_output_drain(void *arg __unused, const char *data, int len) 3049 { 3050 3051 witness_output("%.*s", len, data); 3052 return (len); 3053 } 3054 3055 static void 3056 witness_debugger(int cond, const char *msg) 3057 { 3058 char buf[32]; 3059 struct sbuf sb; 3060 struct stack st; 3061 3062 if (!cond) 3063 return; 3064 3065 if (witness_trace) { 3066 sbuf_new(&sb, buf, sizeof(buf), SBUF_FIXEDLEN); 3067 sbuf_set_drain(&sb, witness_output_drain, NULL); 3068 3069 stack_zero(&st); 3070 stack_save(&st); 3071 witness_output("stack backtrace:\n"); 3072 stack_sbuf_print_ddb(&sb, &st); 3073 3074 sbuf_finish(&sb); 3075 } 3076 3077 #ifdef KDB 3078 if (witness_kdb) 3079 kdb_enter(KDB_WHY_WITNESS, msg); 3080 #endif 3081 } 3082