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