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 #define LI_SLEEPABLE 0x00040000 /* Lock may be held while sleeping. */ 135 136 #ifndef WITNESS_COUNT 137 #define WITNESS_COUNT 1536 138 #endif 139 #define WITNESS_HASH_SIZE 251 /* Prime, gives load factor < 2 */ 140 #define WITNESS_PENDLIST (512 + (MAXCPU * 4)) 141 142 /* Allocate 256 KB of stack data space */ 143 #define WITNESS_LO_DATA_COUNT 2048 144 145 /* Prime, gives load factor of ~2 at full load */ 146 #define WITNESS_LO_HASH_SIZE 1021 147 148 /* 149 * XXX: This is somewhat bogus, as we assume here that at most 2048 threads 150 * will hold LOCK_NCHILDREN locks. We handle failure ok, and we should 151 * probably be safe for the most part, but it's still a SWAG. 152 */ 153 #define LOCK_NCHILDREN 5 154 #define LOCK_CHILDCOUNT 2048 155 156 #define MAX_W_NAME 64 157 158 #define FULLGRAPH_SBUF_SIZE 512 159 160 /* 161 * These flags go in the witness relationship matrix and describe the 162 * relationship between any two struct witness objects. 163 */ 164 #define WITNESS_UNRELATED 0x00 /* No lock order relation. */ 165 #define WITNESS_PARENT 0x01 /* Parent, aka direct ancestor. */ 166 #define WITNESS_ANCESTOR 0x02 /* Direct or indirect ancestor. */ 167 #define WITNESS_CHILD 0x04 /* Child, aka direct descendant. */ 168 #define WITNESS_DESCENDANT 0x08 /* Direct or indirect descendant. */ 169 #define WITNESS_ANCESTOR_MASK (WITNESS_PARENT | WITNESS_ANCESTOR) 170 #define WITNESS_DESCENDANT_MASK (WITNESS_CHILD | WITNESS_DESCENDANT) 171 #define WITNESS_RELATED_MASK \ 172 (WITNESS_ANCESTOR_MASK | WITNESS_DESCENDANT_MASK) 173 #define WITNESS_REVERSAL 0x10 /* A lock order reversal has been 174 * observed. */ 175 #define WITNESS_RESERVED1 0x20 /* Unused flag, reserved. */ 176 #define WITNESS_RESERVED2 0x40 /* Unused flag, reserved. */ 177 #define WITNESS_LOCK_ORDER_KNOWN 0x80 /* This lock order is known. */ 178 179 /* Descendant to ancestor flags */ 180 #define WITNESS_DTOA(x) (((x) & WITNESS_RELATED_MASK) >> 2) 181 182 /* Ancestor to descendant flags */ 183 #define WITNESS_ATOD(x) (((x) & WITNESS_RELATED_MASK) << 2) 184 185 #define WITNESS_INDEX_ASSERT(i) \ 186 MPASS((i) > 0 && (i) <= w_max_used_index && (i) < witness_count) 187 188 static MALLOC_DEFINE(M_WITNESS, "Witness", "Witness"); 189 190 /* 191 * Lock instances. A lock instance is the data associated with a lock while 192 * it is held by witness. For example, a lock instance will hold the 193 * recursion count of a lock. Lock instances are held in lists. Spin locks 194 * are held in a per-cpu list while sleep locks are held in per-thread list. 195 */ 196 struct lock_instance { 197 struct lock_object *li_lock; 198 const char *li_file; 199 int li_line; 200 u_int li_flags; 201 }; 202 203 /* 204 * A simple list type used to build the list of locks held by a thread 205 * or CPU. We can't simply embed the list in struct lock_object since a 206 * lock may be held by more than one thread if it is a shared lock. Locks 207 * are added to the head of the list, so we fill up each list entry from 208 * "the back" logically. To ease some of the arithmetic, we actually fill 209 * in each list entry the normal way (children[0] then children[1], etc.) but 210 * when we traverse the list we read children[count-1] as the first entry 211 * down to children[0] as the final entry. 212 */ 213 struct lock_list_entry { 214 struct lock_list_entry *ll_next; 215 struct lock_instance ll_children[LOCK_NCHILDREN]; 216 u_int ll_count; 217 }; 218 219 /* 220 * The main witness structure. One of these per named lock type in the system 221 * (for example, "vnode interlock"). 222 */ 223 struct witness { 224 char w_name[MAX_W_NAME]; 225 uint32_t w_index; /* Index in the relationship matrix */ 226 struct lock_class *w_class; 227 STAILQ_ENTRY(witness) w_list; /* List of all witnesses. */ 228 STAILQ_ENTRY(witness) w_typelist; /* Witnesses of a type. */ 229 struct witness *w_hash_next; /* Linked list in hash buckets. */ 230 const char *w_file; /* File where last acquired */ 231 uint32_t w_line; /* Line where last acquired */ 232 uint32_t w_refcount; 233 uint16_t w_num_ancestors; /* direct/indirect 234 * ancestor count */ 235 uint16_t w_num_descendants; /* direct/indirect 236 * descendant count */ 237 int16_t w_ddb_level; 238 unsigned w_displayed:1; 239 unsigned w_reversed:1; 240 }; 241 242 STAILQ_HEAD(witness_list, witness); 243 244 /* 245 * The witness hash table. Keys are witness names (const char *), elements are 246 * witness objects (struct witness *). 247 */ 248 struct witness_hash { 249 struct witness *wh_array[WITNESS_HASH_SIZE]; 250 uint32_t wh_size; 251 uint32_t wh_count; 252 }; 253 254 /* 255 * Key type for the lock order data hash table. 256 */ 257 struct witness_lock_order_key { 258 uint16_t from; 259 uint16_t to; 260 }; 261 262 struct witness_lock_order_data { 263 struct stack wlod_stack; 264 struct witness_lock_order_key wlod_key; 265 struct witness_lock_order_data *wlod_next; 266 }; 267 268 /* 269 * The witness lock order data hash table. Keys are witness index tuples 270 * (struct witness_lock_order_key), elements are lock order data objects 271 * (struct witness_lock_order_data). 272 */ 273 struct witness_lock_order_hash { 274 struct witness_lock_order_data *wloh_array[WITNESS_LO_HASH_SIZE]; 275 u_int wloh_size; 276 u_int wloh_count; 277 }; 278 279 struct witness_blessed { 280 const char *b_lock1; 281 const char *b_lock2; 282 }; 283 284 struct witness_pendhelp { 285 const char *wh_type; 286 struct lock_object *wh_lock; 287 }; 288 289 struct witness_order_list_entry { 290 const char *w_name; 291 struct lock_class *w_class; 292 }; 293 294 /* 295 * Returns 0 if one of the locks is a spin lock and the other is not. 296 * Returns 1 otherwise. 297 */ 298 static __inline int 299 witness_lock_type_equal(struct witness *w1, struct witness *w2) 300 { 301 302 return ((w1->w_class->lc_flags & (LC_SLEEPLOCK | LC_SPINLOCK)) == 303 (w2->w_class->lc_flags & (LC_SLEEPLOCK | LC_SPINLOCK))); 304 } 305 306 static __inline int 307 witness_lock_order_key_equal(const struct witness_lock_order_key *a, 308 const struct witness_lock_order_key *b) 309 { 310 311 return (a->from == b->from && a->to == b->to); 312 } 313 314 static int _isitmyx(struct witness *w1, struct witness *w2, int rmask, 315 const char *fname); 316 static void adopt(struct witness *parent, struct witness *child); 317 static int blessed(struct witness *, struct witness *); 318 static void depart(struct witness *w); 319 static struct witness *enroll(const char *description, 320 struct lock_class *lock_class); 321 static struct lock_instance *find_instance(struct lock_list_entry *list, 322 const struct lock_object *lock); 323 static int isitmychild(struct witness *parent, struct witness *child); 324 static int isitmydescendant(struct witness *parent, struct witness *child); 325 static void itismychild(struct witness *parent, struct witness *child); 326 static int sysctl_debug_witness_badstacks(SYSCTL_HANDLER_ARGS); 327 static int sysctl_debug_witness_watch(SYSCTL_HANDLER_ARGS); 328 static int sysctl_debug_witness_fullgraph(SYSCTL_HANDLER_ARGS); 329 static int sysctl_debug_witness_channel(SYSCTL_HANDLER_ARGS); 330 static void witness_add_fullgraph(struct sbuf *sb, struct witness *parent); 331 #ifdef DDB 332 static void witness_ddb_compute_levels(void); 333 static void witness_ddb_display(int(*)(const char *fmt, ...)); 334 static void witness_ddb_display_descendants(int(*)(const char *fmt, ...), 335 struct witness *, int indent); 336 static void witness_ddb_display_list(int(*prnt)(const char *fmt, ...), 337 struct witness_list *list); 338 static void witness_ddb_level_descendants(struct witness *parent, int l); 339 static void witness_ddb_list(struct thread *td); 340 #endif 341 static void witness_debugger(int cond, const char *msg); 342 static void witness_free(struct witness *m); 343 static struct witness *witness_get(void); 344 static uint32_t witness_hash_djb2(const uint8_t *key, uint32_t size); 345 static struct witness *witness_hash_get(const char *key); 346 static void witness_hash_put(struct witness *w); 347 static void witness_init_hash_tables(void); 348 static void witness_increment_graph_generation(void); 349 static void witness_lock_list_free(struct lock_list_entry *lle); 350 static struct lock_list_entry *witness_lock_list_get(void); 351 static int witness_lock_order_add(struct witness *parent, 352 struct witness *child); 353 static int witness_lock_order_check(struct witness *parent, 354 struct witness *child); 355 static struct witness_lock_order_data *witness_lock_order_get( 356 struct witness *parent, 357 struct witness *child); 358 static void witness_list_lock(struct lock_instance *instance, 359 int (*prnt)(const char *fmt, ...)); 360 static int witness_output(const char *fmt, ...) __printflike(1, 2); 361 static int witness_voutput(const char *fmt, va_list ap) __printflike(1, 0); 362 static void witness_setflag(struct lock_object *lock, int flag, int set); 363 364 static SYSCTL_NODE(_debug, OID_AUTO, witness, CTLFLAG_RW | CTLFLAG_MPSAFE, NULL, 365 "Witness Locking"); 366 367 /* 368 * If set to 0, lock order checking is disabled. If set to -1, 369 * witness is completely disabled. Otherwise witness performs full 370 * lock order checking for all locks. At runtime, lock order checking 371 * may be toggled. However, witness cannot be reenabled once it is 372 * completely disabled. 373 */ 374 static int witness_watch = 1; 375 SYSCTL_PROC(_debug_witness, OID_AUTO, watch, 376 CTLFLAG_RWTUN | CTLTYPE_INT | CTLFLAG_MPSAFE, NULL, 0, 377 sysctl_debug_witness_watch, "I", 378 "witness is watching lock operations"); 379 380 #ifdef KDB 381 /* 382 * When KDB is enabled and witness_kdb is 1, it will cause the system 383 * to drop into kdebug() when: 384 * - a lock hierarchy violation occurs 385 * - locks are held when going to sleep. 386 */ 387 #ifdef WITNESS_KDB 388 int witness_kdb = 1; 389 #else 390 int witness_kdb = 0; 391 #endif 392 SYSCTL_INT(_debug_witness, OID_AUTO, kdb, CTLFLAG_RWTUN, &witness_kdb, 0, ""); 393 #endif /* KDB */ 394 395 #if defined(DDB) || defined(KDB) 396 /* 397 * When DDB or KDB is enabled and witness_trace is 1, it will cause the system 398 * to print a stack trace: 399 * - a lock hierarchy violation occurs 400 * - locks are held when going to sleep. 401 */ 402 int witness_trace = 1; 403 SYSCTL_INT(_debug_witness, OID_AUTO, trace, CTLFLAG_RWTUN, &witness_trace, 0, ""); 404 #endif /* DDB || KDB */ 405 406 #ifdef WITNESS_SKIPSPIN 407 int witness_skipspin = 1; 408 #else 409 int witness_skipspin = 0; 410 #endif 411 SYSCTL_INT(_debug_witness, OID_AUTO, skipspin, CTLFLAG_RDTUN, &witness_skipspin, 0, ""); 412 413 int badstack_sbuf_size; 414 415 int witness_count = WITNESS_COUNT; 416 SYSCTL_INT(_debug_witness, OID_AUTO, witness_count, CTLFLAG_RDTUN, 417 &witness_count, 0, ""); 418 419 /* 420 * Output channel for witness messages. By default we print to the console. 421 */ 422 enum witness_channel { 423 WITNESS_CONSOLE, 424 WITNESS_LOG, 425 WITNESS_NONE, 426 }; 427 428 static enum witness_channel witness_channel = WITNESS_CONSOLE; 429 SYSCTL_PROC(_debug_witness, OID_AUTO, output_channel, 430 CTLTYPE_STRING | CTLFLAG_RWTUN | CTLFLAG_MPSAFE, NULL, 0, 431 sysctl_debug_witness_channel, "A", 432 "Output channel for warnings"); 433 434 /* 435 * Call this to print out the relations between locks. 436 */ 437 SYSCTL_PROC(_debug_witness, OID_AUTO, fullgraph, 438 CTLTYPE_STRING | CTLFLAG_RD | CTLFLAG_MPSAFE, NULL, 0, 439 sysctl_debug_witness_fullgraph, "A", 440 "Show locks relation graphs"); 441 442 /* 443 * Call this to print out the witness faulty stacks. 444 */ 445 SYSCTL_PROC(_debug_witness, OID_AUTO, badstacks, 446 CTLTYPE_STRING | CTLFLAG_RD | CTLFLAG_MPSAFE, NULL, 0, 447 sysctl_debug_witness_badstacks, "A", 448 "Show bad witness stacks"); 449 450 static struct mtx w_mtx; 451 452 /* w_list */ 453 static struct witness_list w_free = STAILQ_HEAD_INITIALIZER(w_free); 454 static struct witness_list w_all = STAILQ_HEAD_INITIALIZER(w_all); 455 456 /* w_typelist */ 457 static struct witness_list w_spin = STAILQ_HEAD_INITIALIZER(w_spin); 458 static struct witness_list w_sleep = STAILQ_HEAD_INITIALIZER(w_sleep); 459 460 /* lock list */ 461 static struct lock_list_entry *w_lock_list_free = NULL; 462 static struct witness_pendhelp pending_locks[WITNESS_PENDLIST]; 463 static u_int pending_cnt; 464 465 static int w_free_cnt, w_spin_cnt, w_sleep_cnt; 466 SYSCTL_INT(_debug_witness, OID_AUTO, free_cnt, CTLFLAG_RD, &w_free_cnt, 0, ""); 467 SYSCTL_INT(_debug_witness, OID_AUTO, spin_cnt, CTLFLAG_RD, &w_spin_cnt, 0, ""); 468 SYSCTL_INT(_debug_witness, OID_AUTO, sleep_cnt, CTLFLAG_RD, &w_sleep_cnt, 0, 469 ""); 470 471 static struct witness *w_data; 472 static uint8_t **w_rmatrix; 473 static struct lock_list_entry w_locklistdata[LOCK_CHILDCOUNT]; 474 static struct witness_hash w_hash; /* The witness hash table. */ 475 476 /* The lock order data hash */ 477 static struct witness_lock_order_data w_lodata[WITNESS_LO_DATA_COUNT]; 478 static struct witness_lock_order_data *w_lofree = NULL; 479 static struct witness_lock_order_hash w_lohash; 480 static int w_max_used_index = 0; 481 static unsigned int w_generation = 0; 482 static const char w_notrunning[] = "Witness not running\n"; 483 static const char w_stillcold[] = "Witness is still cold\n"; 484 #ifdef __i386__ 485 static const char w_notallowed[] = "The sysctl is disabled on the arch\n"; 486 #endif 487 488 static struct witness_order_list_entry order_lists[] = { 489 /* 490 * sx locks 491 */ 492 { "proctree", &lock_class_sx }, 493 { "allproc", &lock_class_sx }, 494 { "allprison", &lock_class_sx }, 495 { NULL, NULL }, 496 /* 497 * Various mutexes 498 */ 499 { "Giant", &lock_class_mtx_sleep }, 500 { "pipe mutex", &lock_class_mtx_sleep }, 501 { "sigio lock", &lock_class_mtx_sleep }, 502 { "process group", &lock_class_mtx_sleep }, 503 #ifdef HWPMC_HOOKS 504 { "pmc-sleep", &lock_class_mtx_sleep }, 505 #endif 506 { "process lock", &lock_class_mtx_sleep }, 507 { "session", &lock_class_mtx_sleep }, 508 { "uidinfo hash", &lock_class_rw }, 509 { "time lock", &lock_class_mtx_sleep }, 510 { NULL, NULL }, 511 /* 512 * umtx 513 */ 514 { "umtx lock", &lock_class_mtx_sleep }, 515 { NULL, NULL }, 516 /* 517 * Sockets 518 */ 519 { "accept", &lock_class_mtx_sleep }, 520 { "so_snd", &lock_class_mtx_sleep }, 521 { "so_rcv", &lock_class_mtx_sleep }, 522 { "sellck", &lock_class_mtx_sleep }, 523 { NULL, NULL }, 524 /* 525 * Routing 526 */ 527 { "so_rcv", &lock_class_mtx_sleep }, 528 { "radix node head", &lock_class_rm }, 529 { "rtentry", &lock_class_mtx_sleep }, 530 { "ifaddr", &lock_class_mtx_sleep }, 531 { NULL, NULL }, 532 /* 533 * IPv4 multicast: 534 * protocol locks before interface locks, after UDP locks. 535 */ 536 { "in_multi_sx", &lock_class_sx }, 537 { "udpinp", &lock_class_rw }, 538 { "in_multi_list_mtx", &lock_class_mtx_sleep }, 539 { "igmp_mtx", &lock_class_mtx_sleep }, 540 { "ifnet_rw", &lock_class_rw }, 541 { "if_addr_lock", &lock_class_mtx_sleep }, 542 { NULL, NULL }, 543 /* 544 * IPv6 multicast: 545 * protocol locks before interface locks, after UDP locks. 546 */ 547 { "in6_multi_sx", &lock_class_sx }, 548 { "udpinp", &lock_class_rw }, 549 { "in6_multi_list_mtx", &lock_class_mtx_sleep }, 550 { "mld_mtx", &lock_class_mtx_sleep }, 551 { "ifnet_rw", &lock_class_rw }, 552 { "if_addr_lock", &lock_class_mtx_sleep }, 553 { NULL, NULL }, 554 /* 555 * UNIX Domain Sockets 556 */ 557 { "unp_link_rwlock", &lock_class_rw }, 558 { "unp_list_lock", &lock_class_mtx_sleep }, 559 { "unp", &lock_class_mtx_sleep }, 560 { "so_snd", &lock_class_mtx_sleep }, 561 { NULL, NULL }, 562 /* 563 * UDP/IP 564 */ 565 { "udp", &lock_class_mtx_sleep }, 566 { "udpinp", &lock_class_rw }, 567 { "so_snd", &lock_class_mtx_sleep }, 568 { NULL, NULL }, 569 /* 570 * TCP/IP 571 */ 572 { "tcp", &lock_class_mtx_sleep }, 573 { "tcpinp", &lock_class_rw }, 574 { "so_snd", &lock_class_mtx_sleep }, 575 { NULL, NULL }, 576 /* 577 * BPF 578 */ 579 { "bpf global lock", &lock_class_sx }, 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 { "devthrd", &lock_class_mtx_sleep }, 613 { NULL, NULL }, 614 /* 615 * VM 616 */ 617 { "vm map (user)", &lock_class_sx }, 618 { "vm object", &lock_class_rw }, 619 { "vm page", &lock_class_mtx_sleep }, 620 { "pmap pv global", &lock_class_rw }, 621 { "pmap", &lock_class_mtx_sleep }, 622 { "pmap pv list", &lock_class_rw }, 623 { "vm page free queue", &lock_class_mtx_sleep }, 624 { "vm pagequeue", &lock_class_mtx_sleep }, 625 { NULL, NULL }, 626 /* 627 * kqueue/VFS interaction 628 */ 629 { "kqueue", &lock_class_mtx_sleep }, 630 { "struct mount mtx", &lock_class_mtx_sleep }, 631 { "vnode interlock", &lock_class_mtx_sleep }, 632 { NULL, NULL }, 633 /* 634 * VFS namecache 635 */ 636 { "ncvn", &lock_class_mtx_sleep }, 637 { "ncbuc", &lock_class_rw }, 638 { "vnode interlock", &lock_class_mtx_sleep }, 639 { "ncneg", &lock_class_mtx_sleep }, 640 { NULL, NULL }, 641 /* 642 * ZFS locking 643 */ 644 { "dn->dn_mtx", &lock_class_sx }, 645 { "dr->dt.di.dr_mtx", &lock_class_sx }, 646 { "db->db_mtx", &lock_class_sx }, 647 { NULL, NULL }, 648 /* 649 * TCP log locks 650 */ 651 { "TCP ID tree", &lock_class_rw }, 652 { "tcp log id bucket", &lock_class_mtx_sleep }, 653 { "tcpinp", &lock_class_rw }, 654 { "TCP log expireq", &lock_class_mtx_sleep }, 655 { NULL, NULL }, 656 /* 657 * spin locks 658 */ 659 #ifdef SMP 660 { "ap boot", &lock_class_mtx_spin }, 661 #endif 662 { "rm.mutex_mtx", &lock_class_mtx_spin }, 663 { "sio", &lock_class_mtx_spin }, 664 #ifdef __i386__ 665 { "cy", &lock_class_mtx_spin }, 666 #endif 667 { "scc_hwmtx", &lock_class_mtx_spin }, 668 { "uart_hwmtx", &lock_class_mtx_spin }, 669 { "fast_taskqueue", &lock_class_mtx_spin }, 670 { "intr table", &lock_class_mtx_spin }, 671 { "process slock", &lock_class_mtx_spin }, 672 { "syscons video lock", &lock_class_mtx_spin }, 673 { "sleepq chain", &lock_class_mtx_spin }, 674 { "rm_spinlock", &lock_class_mtx_spin }, 675 { "turnstile chain", &lock_class_mtx_spin }, 676 { "turnstile lock", &lock_class_mtx_spin }, 677 { "sched lock", &lock_class_mtx_spin }, 678 { "td_contested", &lock_class_mtx_spin }, 679 { "callout", &lock_class_mtx_spin }, 680 { "entropy harvest mutex", &lock_class_mtx_spin }, 681 #ifdef SMP 682 { "smp rendezvous", &lock_class_mtx_spin }, 683 #endif 684 #ifdef __powerpc__ 685 { "tlb0", &lock_class_mtx_spin }, 686 #endif 687 { NULL, NULL }, 688 { "sched lock", &lock_class_mtx_spin }, 689 #ifdef HWPMC_HOOKS 690 { "pmc-per-proc", &lock_class_mtx_spin }, 691 #endif 692 { NULL, NULL }, 693 /* 694 * leaf locks 695 */ 696 { "intrcnt", &lock_class_mtx_spin }, 697 { "icu", &lock_class_mtx_spin }, 698 #ifdef __i386__ 699 { "allpmaps", &lock_class_mtx_spin }, 700 { "descriptor tables", &lock_class_mtx_spin }, 701 #endif 702 { "clk", &lock_class_mtx_spin }, 703 { "cpuset", &lock_class_mtx_spin }, 704 { "mprof lock", &lock_class_mtx_spin }, 705 { "zombie lock", &lock_class_mtx_spin }, 706 { "ALD Queue", &lock_class_mtx_spin }, 707 #if defined(__i386__) || defined(__amd64__) 708 { "pcicfg", &lock_class_mtx_spin }, 709 { "NDIS thread lock", &lock_class_mtx_spin }, 710 #endif 711 { "tw_osl_io_lock", &lock_class_mtx_spin }, 712 { "tw_osl_q_lock", &lock_class_mtx_spin }, 713 { "tw_cl_io_lock", &lock_class_mtx_spin }, 714 { "tw_cl_intr_lock", &lock_class_mtx_spin }, 715 { "tw_cl_gen_lock", &lock_class_mtx_spin }, 716 #ifdef HWPMC_HOOKS 717 { "pmc-leaf", &lock_class_mtx_spin }, 718 #endif 719 { "blocked lock", &lock_class_mtx_spin }, 720 { NULL, NULL }, 721 { NULL, NULL } 722 }; 723 724 /* 725 * Pairs of locks which have been blessed. Witness does not complain about 726 * order problems with blessed lock pairs. Please do not add an entry to the 727 * table without an explanatory comment. 728 */ 729 static struct witness_blessed blessed_list[] = { 730 /* 731 * See the comment in ufs_dirhash.c. Basically, a vnode lock serializes 732 * both lock orders, so a deadlock cannot happen as a result of this 733 * LOR. 734 */ 735 { "dirhash", "bufwait" }, 736 737 /* 738 * A UFS vnode may be locked in vget() while a buffer belonging to the 739 * parent directory vnode is locked. 740 */ 741 { "ufs", "bufwait" }, 742 }; 743 744 /* 745 * This global is set to 0 once it becomes safe to use the witness code. 746 */ 747 static int witness_cold = 1; 748 749 /* 750 * This global is set to 1 once the static lock orders have been enrolled 751 * so that a warning can be issued for any spin locks enrolled later. 752 */ 753 static int witness_spin_warn = 0; 754 755 /* Trim useless garbage from filenames. */ 756 static const char * 757 fixup_filename(const char *file) 758 { 759 760 if (file == NULL) 761 return (NULL); 762 while (strncmp(file, "../", 3) == 0) 763 file += 3; 764 return (file); 765 } 766 767 /* 768 * Calculate the size of early witness structures. 769 */ 770 int 771 witness_startup_count(void) 772 { 773 int sz; 774 775 sz = sizeof(struct witness) * witness_count; 776 sz += sizeof(*w_rmatrix) * (witness_count + 1); 777 sz += sizeof(*w_rmatrix[0]) * (witness_count + 1) * 778 (witness_count + 1); 779 780 return (sz); 781 } 782 783 /* 784 * The WITNESS-enabled diagnostic code. Note that the witness code does 785 * assume that the early boot is single-threaded at least until after this 786 * routine is completed. 787 */ 788 void 789 witness_startup(void *mem) 790 { 791 struct lock_object *lock; 792 struct witness_order_list_entry *order; 793 struct witness *w, *w1; 794 uintptr_t p; 795 int i; 796 797 p = (uintptr_t)mem; 798 w_data = (void *)p; 799 p += sizeof(struct witness) * witness_count; 800 801 w_rmatrix = (void *)p; 802 p += sizeof(*w_rmatrix) * (witness_count + 1); 803 804 for (i = 0; i < witness_count + 1; i++) { 805 w_rmatrix[i] = (void *)p; 806 p += sizeof(*w_rmatrix[i]) * (witness_count + 1); 807 } 808 badstack_sbuf_size = witness_count * 256; 809 810 /* 811 * We have to release Giant before initializing its witness 812 * structure so that WITNESS doesn't get confused. 813 */ 814 mtx_unlock(&Giant); 815 mtx_assert(&Giant, MA_NOTOWNED); 816 817 CTR1(KTR_WITNESS, "%s: initializing witness", __func__); 818 mtx_init(&w_mtx, "witness lock", NULL, MTX_SPIN | MTX_QUIET | 819 MTX_NOWITNESS | MTX_NOPROFILE); 820 for (i = witness_count - 1; i >= 0; i--) { 821 w = &w_data[i]; 822 memset(w, 0, sizeof(*w)); 823 w_data[i].w_index = i; /* Witness index never changes. */ 824 witness_free(w); 825 } 826 KASSERT(STAILQ_FIRST(&w_free)->w_index == 0, 827 ("%s: Invalid list of free witness objects", __func__)); 828 829 /* Witness with index 0 is not used to aid in debugging. */ 830 STAILQ_REMOVE_HEAD(&w_free, w_list); 831 w_free_cnt--; 832 833 for (i = 0; i < witness_count; i++) { 834 memset(w_rmatrix[i], 0, sizeof(*w_rmatrix[i]) * 835 (witness_count + 1)); 836 } 837 838 for (i = 0; i < LOCK_CHILDCOUNT; i++) 839 witness_lock_list_free(&w_locklistdata[i]); 840 witness_init_hash_tables(); 841 842 /* First add in all the specified order lists. */ 843 for (order = order_lists; order->w_name != NULL; order++) { 844 w = enroll(order->w_name, order->w_class); 845 if (w == NULL) 846 continue; 847 w->w_file = "order list"; 848 for (order++; order->w_name != NULL; order++) { 849 w1 = enroll(order->w_name, order->w_class); 850 if (w1 == NULL) 851 continue; 852 w1->w_file = "order list"; 853 itismychild(w, w1); 854 w = w1; 855 } 856 } 857 witness_spin_warn = 1; 858 859 /* Iterate through all locks and add them to witness. */ 860 for (i = 0; pending_locks[i].wh_lock != NULL; i++) { 861 lock = pending_locks[i].wh_lock; 862 KASSERT(lock->lo_flags & LO_WITNESS, 863 ("%s: lock %s is on pending list but not LO_WITNESS", 864 __func__, lock->lo_name)); 865 lock->lo_witness = enroll(pending_locks[i].wh_type, 866 LOCK_CLASS(lock)); 867 } 868 869 /* Mark the witness code as being ready for use. */ 870 witness_cold = 0; 871 872 mtx_lock(&Giant); 873 } 874 875 void 876 witness_init(struct lock_object *lock, const char *type) 877 { 878 struct lock_class *class; 879 880 /* Various sanity checks. */ 881 class = LOCK_CLASS(lock); 882 if ((lock->lo_flags & LO_RECURSABLE) != 0 && 883 (class->lc_flags & LC_RECURSABLE) == 0) 884 kassert_panic("%s: lock (%s) %s can not be recursable", 885 __func__, class->lc_name, lock->lo_name); 886 if ((lock->lo_flags & LO_SLEEPABLE) != 0 && 887 (class->lc_flags & LC_SLEEPABLE) == 0) 888 kassert_panic("%s: lock (%s) %s can not be sleepable", 889 __func__, class->lc_name, lock->lo_name); 890 if ((lock->lo_flags & LO_UPGRADABLE) != 0 && 891 (class->lc_flags & LC_UPGRADABLE) == 0) 892 kassert_panic("%s: lock (%s) %s can not be upgradable", 893 __func__, class->lc_name, lock->lo_name); 894 895 /* 896 * If we shouldn't watch this lock, then just clear lo_witness. 897 * Otherwise, if witness_cold is set, then it is too early to 898 * enroll this lock, so defer it to witness_initialize() by adding 899 * it to the pending_locks list. If it is not too early, then enroll 900 * the lock now. 901 */ 902 if (witness_watch < 1 || KERNEL_PANICKED() || 903 (lock->lo_flags & LO_WITNESS) == 0) 904 lock->lo_witness = NULL; 905 else if (witness_cold) { 906 pending_locks[pending_cnt].wh_lock = lock; 907 pending_locks[pending_cnt++].wh_type = type; 908 if (pending_cnt > WITNESS_PENDLIST) 909 panic("%s: pending locks list is too small, " 910 "increase WITNESS_PENDLIST\n", 911 __func__); 912 } else 913 lock->lo_witness = enroll(type, class); 914 } 915 916 void 917 witness_destroy(struct lock_object *lock) 918 { 919 struct lock_class *class; 920 struct witness *w; 921 922 class = LOCK_CLASS(lock); 923 924 if (witness_cold) 925 panic("lock (%s) %s destroyed while witness_cold", 926 class->lc_name, lock->lo_name); 927 928 /* XXX: need to verify that no one holds the lock */ 929 if ((lock->lo_flags & LO_WITNESS) == 0 || lock->lo_witness == NULL) 930 return; 931 w = lock->lo_witness; 932 933 mtx_lock_spin(&w_mtx); 934 MPASS(w->w_refcount > 0); 935 w->w_refcount--; 936 937 if (w->w_refcount == 0) 938 depart(w); 939 mtx_unlock_spin(&w_mtx); 940 } 941 942 #ifdef DDB 943 static void 944 witness_ddb_compute_levels(void) 945 { 946 struct witness *w; 947 948 /* 949 * First clear all levels. 950 */ 951 STAILQ_FOREACH(w, &w_all, w_list) 952 w->w_ddb_level = -1; 953 954 /* 955 * Look for locks with no parents and level all their descendants. 956 */ 957 STAILQ_FOREACH(w, &w_all, w_list) { 958 959 /* If the witness has ancestors (is not a root), skip it. */ 960 if (w->w_num_ancestors > 0) 961 continue; 962 witness_ddb_level_descendants(w, 0); 963 } 964 } 965 966 static void 967 witness_ddb_level_descendants(struct witness *w, int l) 968 { 969 int i; 970 971 if (w->w_ddb_level >= l) 972 return; 973 974 w->w_ddb_level = l; 975 l++; 976 977 for (i = 1; i <= w_max_used_index; i++) { 978 if (w_rmatrix[w->w_index][i] & WITNESS_PARENT) 979 witness_ddb_level_descendants(&w_data[i], l); 980 } 981 } 982 983 static void 984 witness_ddb_display_descendants(int(*prnt)(const char *fmt, ...), 985 struct witness *w, int indent) 986 { 987 int i; 988 989 for (i = 0; i < indent; i++) 990 prnt(" "); 991 prnt("%s (type: %s, depth: %d, active refs: %d)", 992 w->w_name, w->w_class->lc_name, 993 w->w_ddb_level, w->w_refcount); 994 if (w->w_displayed) { 995 prnt(" -- (already displayed)\n"); 996 return; 997 } 998 w->w_displayed = 1; 999 if (w->w_file != NULL && w->w_line != 0) 1000 prnt(" -- last acquired @ %s:%d\n", fixup_filename(w->w_file), 1001 w->w_line); 1002 else 1003 prnt(" -- never acquired\n"); 1004 indent++; 1005 WITNESS_INDEX_ASSERT(w->w_index); 1006 for (i = 1; i <= w_max_used_index; i++) { 1007 if (db_pager_quit) 1008 return; 1009 if (w_rmatrix[w->w_index][i] & WITNESS_PARENT) 1010 witness_ddb_display_descendants(prnt, &w_data[i], 1011 indent); 1012 } 1013 } 1014 1015 static void 1016 witness_ddb_display_list(int(*prnt)(const char *fmt, ...), 1017 struct witness_list *list) 1018 { 1019 struct witness *w; 1020 1021 STAILQ_FOREACH(w, list, w_typelist) { 1022 if (w->w_file == NULL || w->w_ddb_level > 0) 1023 continue; 1024 1025 /* This lock has no anscestors - display its descendants. */ 1026 witness_ddb_display_descendants(prnt, w, 0); 1027 if (db_pager_quit) 1028 return; 1029 } 1030 } 1031 1032 static void 1033 witness_ddb_display(int(*prnt)(const char *fmt, ...)) 1034 { 1035 struct witness *w; 1036 1037 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); 1038 witness_ddb_compute_levels(); 1039 1040 /* Clear all the displayed flags. */ 1041 STAILQ_FOREACH(w, &w_all, w_list) 1042 w->w_displayed = 0; 1043 1044 /* 1045 * First, handle sleep locks which have been acquired at least 1046 * once. 1047 */ 1048 prnt("Sleep locks:\n"); 1049 witness_ddb_display_list(prnt, &w_sleep); 1050 if (db_pager_quit) 1051 return; 1052 1053 /* 1054 * Now do spin locks which have been acquired at least once. 1055 */ 1056 prnt("\nSpin locks:\n"); 1057 witness_ddb_display_list(prnt, &w_spin); 1058 if (db_pager_quit) 1059 return; 1060 1061 /* 1062 * Finally, any locks which have not been acquired yet. 1063 */ 1064 prnt("\nLocks which were never acquired:\n"); 1065 STAILQ_FOREACH(w, &w_all, w_list) { 1066 if (w->w_file != NULL || w->w_refcount == 0) 1067 continue; 1068 prnt("%s (type: %s, depth: %d)\n", w->w_name, 1069 w->w_class->lc_name, w->w_ddb_level); 1070 if (db_pager_quit) 1071 return; 1072 } 1073 } 1074 #endif /* DDB */ 1075 1076 int 1077 witness_defineorder(struct lock_object *lock1, struct lock_object *lock2) 1078 { 1079 1080 if (witness_watch == -1 || KERNEL_PANICKED()) 1081 return (0); 1082 1083 /* Require locks that witness knows about. */ 1084 if (lock1 == NULL || lock1->lo_witness == NULL || lock2 == NULL || 1085 lock2->lo_witness == NULL) 1086 return (EINVAL); 1087 1088 mtx_assert(&w_mtx, MA_NOTOWNED); 1089 mtx_lock_spin(&w_mtx); 1090 1091 /* 1092 * If we already have either an explicit or implied lock order that 1093 * is the other way around, then return an error. 1094 */ 1095 if (witness_watch && 1096 isitmydescendant(lock2->lo_witness, lock1->lo_witness)) { 1097 mtx_unlock_spin(&w_mtx); 1098 return (EDOOFUS); 1099 } 1100 1101 /* Try to add the new order. */ 1102 CTR3(KTR_WITNESS, "%s: adding %s as a child of %s", __func__, 1103 lock2->lo_witness->w_name, lock1->lo_witness->w_name); 1104 itismychild(lock1->lo_witness, lock2->lo_witness); 1105 mtx_unlock_spin(&w_mtx); 1106 return (0); 1107 } 1108 1109 void 1110 witness_checkorder(struct lock_object *lock, int flags, const char *file, 1111 int line, struct lock_object *interlock) 1112 { 1113 struct lock_list_entry *lock_list, *lle; 1114 struct lock_instance *lock1, *lock2, *plock; 1115 struct lock_class *class, *iclass; 1116 struct witness *w, *w1; 1117 struct thread *td; 1118 int i, j; 1119 1120 if (witness_cold || witness_watch < 1 || lock->lo_witness == NULL || 1121 KERNEL_PANICKED()) 1122 return; 1123 1124 w = lock->lo_witness; 1125 class = LOCK_CLASS(lock); 1126 td = curthread; 1127 1128 if (class->lc_flags & LC_SLEEPLOCK) { 1129 1130 /* 1131 * Since spin locks include a critical section, this check 1132 * implicitly enforces a lock order of all sleep locks before 1133 * all spin locks. 1134 */ 1135 if (td->td_critnest != 0 && !kdb_active) 1136 kassert_panic("acquiring blockable sleep lock with " 1137 "spinlock or critical section held (%s) %s @ %s:%d", 1138 class->lc_name, lock->lo_name, 1139 fixup_filename(file), line); 1140 1141 /* 1142 * If this is the first lock acquired then just return as 1143 * no order checking is needed. 1144 */ 1145 lock_list = td->td_sleeplocks; 1146 if (lock_list == NULL || lock_list->ll_count == 0) 1147 return; 1148 } else { 1149 1150 /* 1151 * If this is the first lock, just return as no order 1152 * checking is needed. Avoid problems with thread 1153 * migration pinning the thread while checking if 1154 * spinlocks are held. If at least one spinlock is held 1155 * the thread is in a safe path and it is allowed to 1156 * unpin it. 1157 */ 1158 sched_pin(); 1159 lock_list = PCPU_GET(spinlocks); 1160 if (lock_list == NULL || lock_list->ll_count == 0) { 1161 sched_unpin(); 1162 return; 1163 } 1164 sched_unpin(); 1165 } 1166 1167 /* 1168 * Check to see if we are recursing on a lock we already own. If 1169 * so, make sure that we don't mismatch exclusive and shared lock 1170 * acquires. 1171 */ 1172 lock1 = find_instance(lock_list, lock); 1173 if (lock1 != NULL) { 1174 if ((lock1->li_flags & LI_EXCLUSIVE) != 0 && 1175 (flags & LOP_EXCLUSIVE) == 0) { 1176 witness_output("shared lock of (%s) %s @ %s:%d\n", 1177 class->lc_name, lock->lo_name, 1178 fixup_filename(file), line); 1179 witness_output("while exclusively locked from %s:%d\n", 1180 fixup_filename(lock1->li_file), lock1->li_line); 1181 kassert_panic("excl->share"); 1182 } 1183 if ((lock1->li_flags & LI_EXCLUSIVE) == 0 && 1184 (flags & LOP_EXCLUSIVE) != 0) { 1185 witness_output("exclusive lock of (%s) %s @ %s:%d\n", 1186 class->lc_name, lock->lo_name, 1187 fixup_filename(file), line); 1188 witness_output("while share locked from %s:%d\n", 1189 fixup_filename(lock1->li_file), lock1->li_line); 1190 kassert_panic("share->excl"); 1191 } 1192 return; 1193 } 1194 1195 /* Warn if the interlock is not locked exactly once. */ 1196 if (interlock != NULL) { 1197 iclass = LOCK_CLASS(interlock); 1198 lock1 = find_instance(lock_list, interlock); 1199 if (lock1 == NULL) 1200 kassert_panic("interlock (%s) %s not locked @ %s:%d", 1201 iclass->lc_name, interlock->lo_name, 1202 fixup_filename(file), line); 1203 else if ((lock1->li_flags & LI_RECURSEMASK) != 0) 1204 kassert_panic("interlock (%s) %s recursed @ %s:%d", 1205 iclass->lc_name, interlock->lo_name, 1206 fixup_filename(file), line); 1207 } 1208 1209 /* 1210 * Find the previously acquired lock, but ignore interlocks. 1211 */ 1212 plock = &lock_list->ll_children[lock_list->ll_count - 1]; 1213 if (interlock != NULL && plock->li_lock == interlock) { 1214 if (lock_list->ll_count > 1) 1215 plock = 1216 &lock_list->ll_children[lock_list->ll_count - 2]; 1217 else { 1218 lle = lock_list->ll_next; 1219 1220 /* 1221 * The interlock is the only lock we hold, so 1222 * simply return. 1223 */ 1224 if (lle == NULL) 1225 return; 1226 plock = &lle->ll_children[lle->ll_count - 1]; 1227 } 1228 } 1229 1230 /* 1231 * Try to perform most checks without a lock. If this succeeds we 1232 * can skip acquiring the lock and return success. Otherwise we redo 1233 * the check with the lock held to handle races with concurrent updates. 1234 */ 1235 w1 = plock->li_lock->lo_witness; 1236 if (witness_lock_order_check(w1, w)) 1237 return; 1238 1239 mtx_lock_spin(&w_mtx); 1240 if (witness_lock_order_check(w1, w)) { 1241 mtx_unlock_spin(&w_mtx); 1242 return; 1243 } 1244 witness_lock_order_add(w1, w); 1245 1246 /* 1247 * Check for duplicate locks of the same type. Note that we only 1248 * have to check for this on the last lock we just acquired. Any 1249 * other cases will be caught as lock order violations. 1250 */ 1251 if (w1 == w) { 1252 i = w->w_index; 1253 if (!(lock->lo_flags & LO_DUPOK) && !(flags & LOP_DUPOK) && 1254 !(w_rmatrix[i][i] & WITNESS_REVERSAL)) { 1255 w_rmatrix[i][i] |= WITNESS_REVERSAL; 1256 w->w_reversed = 1; 1257 mtx_unlock_spin(&w_mtx); 1258 witness_output( 1259 "acquiring duplicate lock of same type: \"%s\"\n", 1260 w->w_name); 1261 witness_output(" 1st %s @ %s:%d\n", plock->li_lock->lo_name, 1262 fixup_filename(plock->li_file), plock->li_line); 1263 witness_output(" 2nd %s @ %s:%d\n", lock->lo_name, 1264 fixup_filename(file), line); 1265 witness_debugger(1, __func__); 1266 } else 1267 mtx_unlock_spin(&w_mtx); 1268 return; 1269 } 1270 mtx_assert(&w_mtx, MA_OWNED); 1271 1272 /* 1273 * If we know that the lock we are acquiring comes after 1274 * the lock we most recently acquired in the lock order tree, 1275 * then there is no need for any further checks. 1276 */ 1277 if (isitmychild(w1, w)) 1278 goto out; 1279 1280 for (j = 0, lle = lock_list; lle != NULL; lle = lle->ll_next) { 1281 for (i = lle->ll_count - 1; i >= 0; i--, j++) { 1282 1283 MPASS(j < LOCK_CHILDCOUNT * LOCK_NCHILDREN); 1284 lock1 = &lle->ll_children[i]; 1285 1286 /* 1287 * Ignore the interlock. 1288 */ 1289 if (interlock == lock1->li_lock) 1290 continue; 1291 1292 /* 1293 * If this lock doesn't undergo witness checking, 1294 * then skip it. 1295 */ 1296 w1 = lock1->li_lock->lo_witness; 1297 if (w1 == NULL) { 1298 KASSERT((lock1->li_lock->lo_flags & LO_WITNESS) == 0, 1299 ("lock missing witness structure")); 1300 continue; 1301 } 1302 1303 /* 1304 * If we are locking Giant and this is a sleepable 1305 * lock, then skip it. 1306 */ 1307 if ((lock1->li_flags & LI_SLEEPABLE) != 0 && 1308 lock == &Giant.lock_object) 1309 continue; 1310 1311 /* 1312 * If we are locking a sleepable lock and this lock 1313 * is Giant, then skip it. 1314 */ 1315 if ((lock->lo_flags & LO_SLEEPABLE) != 0 && 1316 (flags & LOP_NOSLEEP) == 0 && 1317 lock1->li_lock == &Giant.lock_object) 1318 continue; 1319 1320 /* 1321 * If we are locking a sleepable lock and this lock 1322 * isn't sleepable, we want to treat it as a lock 1323 * order violation to enfore a general lock order of 1324 * sleepable locks before non-sleepable locks. 1325 */ 1326 if ((lock->lo_flags & LO_SLEEPABLE) != 0 && 1327 (flags & LOP_NOSLEEP) == 0 && 1328 (lock1->li_flags & LI_SLEEPABLE) == 0) 1329 goto reversal; 1330 1331 /* 1332 * If we are locking Giant and this is a non-sleepable 1333 * lock, then treat it as a reversal. 1334 */ 1335 if ((lock1->li_flags & LI_SLEEPABLE) == 0 && 1336 lock == &Giant.lock_object) 1337 goto reversal; 1338 1339 /* 1340 * Check the lock order hierarchy for a reveresal. 1341 */ 1342 if (!isitmydescendant(w, w1)) 1343 continue; 1344 reversal: 1345 1346 /* 1347 * We have a lock order violation, check to see if it 1348 * is allowed or has already been yelled about. 1349 */ 1350 1351 /* Bail if this violation is known */ 1352 if (w_rmatrix[w1->w_index][w->w_index] & WITNESS_REVERSAL) 1353 goto out; 1354 1355 /* Record this as a violation */ 1356 w_rmatrix[w1->w_index][w->w_index] |= WITNESS_REVERSAL; 1357 w_rmatrix[w->w_index][w1->w_index] |= WITNESS_REVERSAL; 1358 w->w_reversed = w1->w_reversed = 1; 1359 witness_increment_graph_generation(); 1360 1361 /* 1362 * If the lock order is blessed, bail before logging 1363 * anything. We don't look for other lock order 1364 * violations though, which may be a bug. 1365 */ 1366 if (blessed(w, w1)) 1367 goto out; 1368 mtx_unlock_spin(&w_mtx); 1369 1370 #ifdef WITNESS_NO_VNODE 1371 /* 1372 * There are known LORs between VNODE locks. They are 1373 * not an indication of a bug. VNODE locks are flagged 1374 * as such (LO_IS_VNODE) and we don't yell if the LOR 1375 * is between 2 VNODE locks. 1376 */ 1377 if ((lock->lo_flags & LO_IS_VNODE) != 0 && 1378 (lock1->li_lock->lo_flags & LO_IS_VNODE) != 0) 1379 return; 1380 #endif 1381 1382 /* 1383 * Ok, yell about it. 1384 */ 1385 if ((lock->lo_flags & LO_SLEEPABLE) != 0 && 1386 (flags & LOP_NOSLEEP) == 0 && 1387 (lock1->li_flags & LI_SLEEPABLE) == 0) 1388 witness_output( 1389 "lock order reversal: (sleepable after non-sleepable)\n"); 1390 else if ((lock1->li_flags & LI_SLEEPABLE) == 0 1391 && lock == &Giant.lock_object) 1392 witness_output( 1393 "lock order reversal: (Giant after non-sleepable)\n"); 1394 else 1395 witness_output("lock order reversal:\n"); 1396 1397 /* 1398 * Try to locate an earlier lock with 1399 * witness w in our list. 1400 */ 1401 do { 1402 lock2 = &lle->ll_children[i]; 1403 MPASS(lock2->li_lock != NULL); 1404 if (lock2->li_lock->lo_witness == w) 1405 break; 1406 if (i == 0 && lle->ll_next != NULL) { 1407 lle = lle->ll_next; 1408 i = lle->ll_count - 1; 1409 MPASS(i >= 0 && i < LOCK_NCHILDREN); 1410 } else 1411 i--; 1412 } while (i >= 0); 1413 if (i < 0) { 1414 witness_output(" 1st %p %s (%s) @ %s:%d\n", 1415 lock1->li_lock, lock1->li_lock->lo_name, 1416 w1->w_name, fixup_filename(lock1->li_file), 1417 lock1->li_line); 1418 witness_output(" 2nd %p %s (%s) @ %s:%d\n", lock, 1419 lock->lo_name, w->w_name, 1420 fixup_filename(file), line); 1421 } else { 1422 witness_output(" 1st %p %s (%s) @ %s:%d\n", 1423 lock2->li_lock, lock2->li_lock->lo_name, 1424 lock2->li_lock->lo_witness->w_name, 1425 fixup_filename(lock2->li_file), 1426 lock2->li_line); 1427 witness_output(" 2nd %p %s (%s) @ %s:%d\n", 1428 lock1->li_lock, lock1->li_lock->lo_name, 1429 w1->w_name, fixup_filename(lock1->li_file), 1430 lock1->li_line); 1431 witness_output(" 3rd %p %s (%s) @ %s:%d\n", lock, 1432 lock->lo_name, w->w_name, 1433 fixup_filename(file), line); 1434 } 1435 witness_debugger(1, __func__); 1436 return; 1437 } 1438 } 1439 1440 /* 1441 * If requested, build a new lock order. However, don't build a new 1442 * relationship between a sleepable lock and Giant if it is in the 1443 * wrong direction. The correct lock order is that sleepable locks 1444 * always come before Giant. 1445 */ 1446 if (flags & LOP_NEWORDER && 1447 !(plock->li_lock == &Giant.lock_object && 1448 (lock->lo_flags & LO_SLEEPABLE) != 0 && 1449 (flags & LOP_NOSLEEP) == 0)) { 1450 CTR3(KTR_WITNESS, "%s: adding %s as a child of %s", __func__, 1451 w->w_name, plock->li_lock->lo_witness->w_name); 1452 itismychild(plock->li_lock->lo_witness, w); 1453 } 1454 out: 1455 mtx_unlock_spin(&w_mtx); 1456 } 1457 1458 void 1459 witness_lock(struct lock_object *lock, int flags, const char *file, int line) 1460 { 1461 struct lock_list_entry **lock_list, *lle; 1462 struct lock_instance *instance; 1463 struct witness *w; 1464 struct thread *td; 1465 1466 if (witness_cold || witness_watch == -1 || lock->lo_witness == NULL || 1467 KERNEL_PANICKED()) 1468 return; 1469 w = lock->lo_witness; 1470 td = curthread; 1471 1472 /* Determine lock list for this lock. */ 1473 if (LOCK_CLASS(lock)->lc_flags & LC_SLEEPLOCK) 1474 lock_list = &td->td_sleeplocks; 1475 else 1476 lock_list = PCPU_PTR(spinlocks); 1477 1478 /* Check to see if we are recursing on a lock we already own. */ 1479 instance = find_instance(*lock_list, lock); 1480 if (instance != NULL) { 1481 instance->li_flags++; 1482 CTR4(KTR_WITNESS, "%s: pid %d recursed on %s r=%d", __func__, 1483 td->td_proc->p_pid, lock->lo_name, 1484 instance->li_flags & LI_RECURSEMASK); 1485 instance->li_file = file; 1486 instance->li_line = line; 1487 return; 1488 } 1489 1490 /* Update per-witness last file and line acquire. */ 1491 w->w_file = file; 1492 w->w_line = line; 1493 1494 /* Find the next open lock instance in the list and fill it. */ 1495 lle = *lock_list; 1496 if (lle == NULL || lle->ll_count == LOCK_NCHILDREN) { 1497 lle = witness_lock_list_get(); 1498 if (lle == NULL) 1499 return; 1500 lle->ll_next = *lock_list; 1501 CTR3(KTR_WITNESS, "%s: pid %d added lle %p", __func__, 1502 td->td_proc->p_pid, lle); 1503 *lock_list = lle; 1504 } 1505 instance = &lle->ll_children[lle->ll_count++]; 1506 instance->li_lock = lock; 1507 instance->li_line = line; 1508 instance->li_file = file; 1509 instance->li_flags = 0; 1510 if ((flags & LOP_EXCLUSIVE) != 0) 1511 instance->li_flags |= LI_EXCLUSIVE; 1512 if ((lock->lo_flags & LO_SLEEPABLE) != 0 && (flags & LOP_NOSLEEP) == 0) 1513 instance->li_flags |= LI_SLEEPABLE; 1514 CTR4(KTR_WITNESS, "%s: pid %d added %s as lle[%d]", __func__, 1515 td->td_proc->p_pid, lock->lo_name, lle->ll_count - 1); 1516 } 1517 1518 void 1519 witness_upgrade(struct lock_object *lock, int flags, const char *file, int line) 1520 { 1521 struct lock_instance *instance; 1522 struct lock_class *class; 1523 1524 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); 1525 if (lock->lo_witness == NULL || witness_watch == -1 || KERNEL_PANICKED()) 1526 return; 1527 class = LOCK_CLASS(lock); 1528 if (witness_watch) { 1529 if ((lock->lo_flags & LO_UPGRADABLE) == 0) 1530 kassert_panic( 1531 "upgrade of non-upgradable lock (%s) %s @ %s:%d", 1532 class->lc_name, lock->lo_name, 1533 fixup_filename(file), line); 1534 if ((class->lc_flags & LC_SLEEPLOCK) == 0) 1535 kassert_panic( 1536 "upgrade of non-sleep lock (%s) %s @ %s:%d", 1537 class->lc_name, lock->lo_name, 1538 fixup_filename(file), line); 1539 } 1540 instance = find_instance(curthread->td_sleeplocks, lock); 1541 if (instance == NULL) { 1542 kassert_panic("upgrade of unlocked lock (%s) %s @ %s:%d", 1543 class->lc_name, lock->lo_name, 1544 fixup_filename(file), line); 1545 return; 1546 } 1547 if (witness_watch) { 1548 if ((instance->li_flags & LI_EXCLUSIVE) != 0) 1549 kassert_panic( 1550 "upgrade of exclusive lock (%s) %s @ %s:%d", 1551 class->lc_name, lock->lo_name, 1552 fixup_filename(file), line); 1553 if ((instance->li_flags & LI_RECURSEMASK) != 0) 1554 kassert_panic( 1555 "upgrade of recursed lock (%s) %s r=%d @ %s:%d", 1556 class->lc_name, lock->lo_name, 1557 instance->li_flags & LI_RECURSEMASK, 1558 fixup_filename(file), line); 1559 } 1560 instance->li_flags |= LI_EXCLUSIVE; 1561 } 1562 1563 void 1564 witness_downgrade(struct lock_object *lock, int flags, const char *file, 1565 int line) 1566 { 1567 struct lock_instance *instance; 1568 struct lock_class *class; 1569 1570 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); 1571 if (lock->lo_witness == NULL || witness_watch == -1 || KERNEL_PANICKED()) 1572 return; 1573 class = LOCK_CLASS(lock); 1574 if (witness_watch) { 1575 if ((lock->lo_flags & LO_UPGRADABLE) == 0) 1576 kassert_panic( 1577 "downgrade of non-upgradable lock (%s) %s @ %s:%d", 1578 class->lc_name, lock->lo_name, 1579 fixup_filename(file), line); 1580 if ((class->lc_flags & LC_SLEEPLOCK) == 0) 1581 kassert_panic( 1582 "downgrade of non-sleep lock (%s) %s @ %s:%d", 1583 class->lc_name, lock->lo_name, 1584 fixup_filename(file), line); 1585 } 1586 instance = find_instance(curthread->td_sleeplocks, lock); 1587 if (instance == NULL) { 1588 kassert_panic("downgrade of unlocked lock (%s) %s @ %s:%d", 1589 class->lc_name, lock->lo_name, 1590 fixup_filename(file), line); 1591 return; 1592 } 1593 if (witness_watch) { 1594 if ((instance->li_flags & LI_EXCLUSIVE) == 0) 1595 kassert_panic( 1596 "downgrade of shared lock (%s) %s @ %s:%d", 1597 class->lc_name, lock->lo_name, 1598 fixup_filename(file), line); 1599 if ((instance->li_flags & LI_RECURSEMASK) != 0) 1600 kassert_panic( 1601 "downgrade of recursed lock (%s) %s r=%d @ %s:%d", 1602 class->lc_name, lock->lo_name, 1603 instance->li_flags & LI_RECURSEMASK, 1604 fixup_filename(file), line); 1605 } 1606 instance->li_flags &= ~LI_EXCLUSIVE; 1607 } 1608 1609 void 1610 witness_unlock(struct lock_object *lock, int flags, const char *file, int line) 1611 { 1612 struct lock_list_entry **lock_list, *lle; 1613 struct lock_instance *instance; 1614 struct lock_class *class; 1615 struct thread *td; 1616 register_t s; 1617 int i, j; 1618 1619 if (witness_cold || lock->lo_witness == NULL || KERNEL_PANICKED()) 1620 return; 1621 td = curthread; 1622 class = LOCK_CLASS(lock); 1623 1624 /* Find lock instance associated with this lock. */ 1625 if (class->lc_flags & LC_SLEEPLOCK) 1626 lock_list = &td->td_sleeplocks; 1627 else 1628 lock_list = PCPU_PTR(spinlocks); 1629 lle = *lock_list; 1630 for (; *lock_list != NULL; lock_list = &(*lock_list)->ll_next) 1631 for (i = 0; i < (*lock_list)->ll_count; i++) { 1632 instance = &(*lock_list)->ll_children[i]; 1633 if (instance->li_lock == lock) 1634 goto found; 1635 } 1636 1637 /* 1638 * When disabling WITNESS through witness_watch we could end up in 1639 * having registered locks in the td_sleeplocks queue. 1640 * We have to make sure we flush these queues, so just search for 1641 * eventual register locks and remove them. 1642 */ 1643 if (witness_watch > 0) { 1644 kassert_panic("lock (%s) %s not locked @ %s:%d", class->lc_name, 1645 lock->lo_name, fixup_filename(file), line); 1646 return; 1647 } else { 1648 return; 1649 } 1650 found: 1651 1652 /* First, check for shared/exclusive mismatches. */ 1653 if ((instance->li_flags & LI_EXCLUSIVE) != 0 && witness_watch > 0 && 1654 (flags & LOP_EXCLUSIVE) == 0) { 1655 witness_output("shared unlock of (%s) %s @ %s:%d\n", 1656 class->lc_name, lock->lo_name, fixup_filename(file), line); 1657 witness_output("while exclusively locked from %s:%d\n", 1658 fixup_filename(instance->li_file), instance->li_line); 1659 kassert_panic("excl->ushare"); 1660 } 1661 if ((instance->li_flags & LI_EXCLUSIVE) == 0 && witness_watch > 0 && 1662 (flags & LOP_EXCLUSIVE) != 0) { 1663 witness_output("exclusive unlock of (%s) %s @ %s:%d\n", 1664 class->lc_name, lock->lo_name, fixup_filename(file), line); 1665 witness_output("while share locked from %s:%d\n", 1666 fixup_filename(instance->li_file), 1667 instance->li_line); 1668 kassert_panic("share->uexcl"); 1669 } 1670 /* If we are recursed, unrecurse. */ 1671 if ((instance->li_flags & LI_RECURSEMASK) > 0) { 1672 CTR4(KTR_WITNESS, "%s: pid %d unrecursed on %s r=%d", __func__, 1673 td->td_proc->p_pid, instance->li_lock->lo_name, 1674 instance->li_flags); 1675 instance->li_flags--; 1676 return; 1677 } 1678 /* The lock is now being dropped, check for NORELEASE flag */ 1679 if ((instance->li_flags & LI_NORELEASE) != 0 && witness_watch > 0) { 1680 witness_output("forbidden unlock of (%s) %s @ %s:%d\n", 1681 class->lc_name, lock->lo_name, fixup_filename(file), line); 1682 kassert_panic("lock marked norelease"); 1683 } 1684 1685 /* Otherwise, remove this item from the list. */ 1686 s = intr_disable(); 1687 CTR4(KTR_WITNESS, "%s: pid %d removed %s from lle[%d]", __func__, 1688 td->td_proc->p_pid, instance->li_lock->lo_name, 1689 (*lock_list)->ll_count - 1); 1690 for (j = i; j < (*lock_list)->ll_count - 1; j++) 1691 (*lock_list)->ll_children[j] = 1692 (*lock_list)->ll_children[j + 1]; 1693 (*lock_list)->ll_count--; 1694 intr_restore(s); 1695 1696 /* 1697 * In order to reduce contention on w_mtx, we want to keep always an 1698 * head object into lists so that frequent allocation from the 1699 * free witness pool (and subsequent locking) is avoided. 1700 * In order to maintain the current code simple, when the head 1701 * object is totally unloaded it means also that we do not have 1702 * further objects in the list, so the list ownership needs to be 1703 * hand over to another object if the current head needs to be freed. 1704 */ 1705 if ((*lock_list)->ll_count == 0) { 1706 if (*lock_list == lle) { 1707 if (lle->ll_next == NULL) 1708 return; 1709 } else 1710 lle = *lock_list; 1711 *lock_list = lle->ll_next; 1712 CTR3(KTR_WITNESS, "%s: pid %d removed lle %p", __func__, 1713 td->td_proc->p_pid, lle); 1714 witness_lock_list_free(lle); 1715 } 1716 } 1717 1718 void 1719 witness_thread_exit(struct thread *td) 1720 { 1721 struct lock_list_entry *lle; 1722 int i, n; 1723 1724 lle = td->td_sleeplocks; 1725 if (lle == NULL || KERNEL_PANICKED()) 1726 return; 1727 if (lle->ll_count != 0) { 1728 for (n = 0; lle != NULL; lle = lle->ll_next) 1729 for (i = lle->ll_count - 1; i >= 0; i--) { 1730 if (n == 0) 1731 witness_output( 1732 "Thread %p exiting with the following locks held:\n", td); 1733 n++; 1734 witness_list_lock(&lle->ll_children[i], 1735 witness_output); 1736 1737 } 1738 kassert_panic( 1739 "Thread %p cannot exit while holding sleeplocks\n", td); 1740 } 1741 witness_lock_list_free(lle); 1742 } 1743 1744 /* 1745 * Warn if any locks other than 'lock' are held. Flags can be passed in to 1746 * exempt Giant and sleepable locks from the checks as well. If any 1747 * non-exempt locks are held, then a supplied message is printed to the 1748 * output channel along with a list of the offending locks. If indicated in the 1749 * flags then a failure results in a panic as well. 1750 */ 1751 int 1752 witness_warn(int flags, struct lock_object *lock, const char *fmt, ...) 1753 { 1754 struct lock_list_entry *lock_list, *lle; 1755 struct lock_instance *lock1; 1756 struct thread *td; 1757 va_list ap; 1758 int i, n; 1759 1760 if (witness_cold || witness_watch < 1 || KERNEL_PANICKED()) 1761 return (0); 1762 n = 0; 1763 td = curthread; 1764 for (lle = td->td_sleeplocks; lle != NULL; lle = lle->ll_next) 1765 for (i = lle->ll_count - 1; i >= 0; i--) { 1766 lock1 = &lle->ll_children[i]; 1767 if (lock1->li_lock == lock) 1768 continue; 1769 if (flags & WARN_GIANTOK && 1770 lock1->li_lock == &Giant.lock_object) 1771 continue; 1772 if (flags & WARN_SLEEPOK && 1773 (lock1->li_flags & LI_SLEEPABLE) != 0) 1774 continue; 1775 if (n == 0) { 1776 va_start(ap, fmt); 1777 vprintf(fmt, ap); 1778 va_end(ap); 1779 printf(" with the following %slocks held:\n", 1780 (flags & WARN_SLEEPOK) != 0 ? 1781 "non-sleepable " : ""); 1782 } 1783 n++; 1784 witness_list_lock(lock1, printf); 1785 } 1786 1787 /* 1788 * Pin the thread in order to avoid problems with thread migration. 1789 * Once that all verifies are passed about spinlocks ownership, 1790 * the thread is in a safe path and it can be unpinned. 1791 */ 1792 sched_pin(); 1793 lock_list = PCPU_GET(spinlocks); 1794 if (lock_list != NULL && lock_list->ll_count != 0) { 1795 sched_unpin(); 1796 1797 /* 1798 * We should only have one spinlock and as long as 1799 * the flags cannot match for this locks class, 1800 * check if the first spinlock is the one curthread 1801 * should hold. 1802 */ 1803 lock1 = &lock_list->ll_children[lock_list->ll_count - 1]; 1804 if (lock_list->ll_count == 1 && lock_list->ll_next == NULL && 1805 lock1->li_lock == lock && n == 0) 1806 return (0); 1807 1808 va_start(ap, fmt); 1809 vprintf(fmt, ap); 1810 va_end(ap); 1811 printf(" with the following %slocks held:\n", 1812 (flags & WARN_SLEEPOK) != 0 ? "non-sleepable " : ""); 1813 n += witness_list_locks(&lock_list, printf); 1814 } else 1815 sched_unpin(); 1816 if (flags & WARN_PANIC && n) 1817 kassert_panic("%s", __func__); 1818 else 1819 witness_debugger(n, __func__); 1820 return (n); 1821 } 1822 1823 const char * 1824 witness_file(struct lock_object *lock) 1825 { 1826 struct witness *w; 1827 1828 if (witness_cold || witness_watch < 1 || lock->lo_witness == NULL) 1829 return ("?"); 1830 w = lock->lo_witness; 1831 return (w->w_file); 1832 } 1833 1834 int 1835 witness_line(struct lock_object *lock) 1836 { 1837 struct witness *w; 1838 1839 if (witness_cold || witness_watch < 1 || lock->lo_witness == NULL) 1840 return (0); 1841 w = lock->lo_witness; 1842 return (w->w_line); 1843 } 1844 1845 static struct witness * 1846 enroll(const char *description, struct lock_class *lock_class) 1847 { 1848 struct witness *w; 1849 1850 MPASS(description != NULL); 1851 1852 if (witness_watch == -1 || KERNEL_PANICKED()) 1853 return (NULL); 1854 if ((lock_class->lc_flags & LC_SPINLOCK)) { 1855 if (witness_skipspin) 1856 return (NULL); 1857 } else if ((lock_class->lc_flags & LC_SLEEPLOCK) == 0) { 1858 kassert_panic("lock class %s is not sleep or spin", 1859 lock_class->lc_name); 1860 return (NULL); 1861 } 1862 1863 mtx_lock_spin(&w_mtx); 1864 w = witness_hash_get(description); 1865 if (w) 1866 goto found; 1867 if ((w = witness_get()) == NULL) 1868 return (NULL); 1869 MPASS(strlen(description) < MAX_W_NAME); 1870 strcpy(w->w_name, description); 1871 w->w_class = lock_class; 1872 w->w_refcount = 1; 1873 STAILQ_INSERT_HEAD(&w_all, w, w_list); 1874 if (lock_class->lc_flags & LC_SPINLOCK) { 1875 STAILQ_INSERT_HEAD(&w_spin, w, w_typelist); 1876 w_spin_cnt++; 1877 } else if (lock_class->lc_flags & LC_SLEEPLOCK) { 1878 STAILQ_INSERT_HEAD(&w_sleep, w, w_typelist); 1879 w_sleep_cnt++; 1880 } 1881 1882 /* Insert new witness into the hash */ 1883 witness_hash_put(w); 1884 witness_increment_graph_generation(); 1885 mtx_unlock_spin(&w_mtx); 1886 return (w); 1887 found: 1888 w->w_refcount++; 1889 if (w->w_refcount == 1) 1890 w->w_class = lock_class; 1891 mtx_unlock_spin(&w_mtx); 1892 if (lock_class != w->w_class) 1893 kassert_panic( 1894 "lock (%s) %s does not match earlier (%s) lock", 1895 description, lock_class->lc_name, 1896 w->w_class->lc_name); 1897 return (w); 1898 } 1899 1900 static void 1901 depart(struct witness *w) 1902 { 1903 1904 MPASS(w->w_refcount == 0); 1905 if (w->w_class->lc_flags & LC_SLEEPLOCK) { 1906 w_sleep_cnt--; 1907 } else { 1908 w_spin_cnt--; 1909 } 1910 /* 1911 * Set file to NULL as it may point into a loadable module. 1912 */ 1913 w->w_file = NULL; 1914 w->w_line = 0; 1915 witness_increment_graph_generation(); 1916 } 1917 1918 static void 1919 adopt(struct witness *parent, struct witness *child) 1920 { 1921 int pi, ci, i, j; 1922 1923 if (witness_cold == 0) 1924 mtx_assert(&w_mtx, MA_OWNED); 1925 1926 /* If the relationship is already known, there's no work to be done. */ 1927 if (isitmychild(parent, child)) 1928 return; 1929 1930 /* When the structure of the graph changes, bump up the generation. */ 1931 witness_increment_graph_generation(); 1932 1933 /* 1934 * The hard part ... create the direct relationship, then propagate all 1935 * indirect relationships. 1936 */ 1937 pi = parent->w_index; 1938 ci = child->w_index; 1939 WITNESS_INDEX_ASSERT(pi); 1940 WITNESS_INDEX_ASSERT(ci); 1941 MPASS(pi != ci); 1942 w_rmatrix[pi][ci] |= WITNESS_PARENT; 1943 w_rmatrix[ci][pi] |= WITNESS_CHILD; 1944 1945 /* 1946 * If parent was not already an ancestor of child, 1947 * then we increment the descendant and ancestor counters. 1948 */ 1949 if ((w_rmatrix[pi][ci] & WITNESS_ANCESTOR) == 0) { 1950 parent->w_num_descendants++; 1951 child->w_num_ancestors++; 1952 } 1953 1954 /* 1955 * Find each ancestor of 'pi'. Note that 'pi' itself is counted as 1956 * an ancestor of 'pi' during this loop. 1957 */ 1958 for (i = 1; i <= w_max_used_index; i++) { 1959 if ((w_rmatrix[i][pi] & WITNESS_ANCESTOR_MASK) == 0 && 1960 (i != pi)) 1961 continue; 1962 1963 /* Find each descendant of 'i' and mark it as a descendant. */ 1964 for (j = 1; j <= w_max_used_index; j++) { 1965 1966 /* 1967 * Skip children that are already marked as 1968 * descendants of 'i'. 1969 */ 1970 if (w_rmatrix[i][j] & WITNESS_ANCESTOR_MASK) 1971 continue; 1972 1973 /* 1974 * We are only interested in descendants of 'ci'. Note 1975 * that 'ci' itself is counted as a descendant of 'ci'. 1976 */ 1977 if ((w_rmatrix[ci][j] & WITNESS_ANCESTOR_MASK) == 0 && 1978 (j != ci)) 1979 continue; 1980 w_rmatrix[i][j] |= WITNESS_ANCESTOR; 1981 w_rmatrix[j][i] |= WITNESS_DESCENDANT; 1982 w_data[i].w_num_descendants++; 1983 w_data[j].w_num_ancestors++; 1984 1985 /* 1986 * Make sure we aren't marking a node as both an 1987 * ancestor and descendant. We should have caught 1988 * this as a lock order reversal earlier. 1989 */ 1990 if ((w_rmatrix[i][j] & WITNESS_ANCESTOR_MASK) && 1991 (w_rmatrix[i][j] & WITNESS_DESCENDANT_MASK)) { 1992 printf("witness rmatrix paradox! [%d][%d]=%d " 1993 "both ancestor and descendant\n", 1994 i, j, w_rmatrix[i][j]); 1995 kdb_backtrace(); 1996 printf("Witness disabled.\n"); 1997 witness_watch = -1; 1998 } 1999 if ((w_rmatrix[j][i] & WITNESS_ANCESTOR_MASK) && 2000 (w_rmatrix[j][i] & WITNESS_DESCENDANT_MASK)) { 2001 printf("witness rmatrix paradox! [%d][%d]=%d " 2002 "both ancestor and descendant\n", 2003 j, i, w_rmatrix[j][i]); 2004 kdb_backtrace(); 2005 printf("Witness disabled.\n"); 2006 witness_watch = -1; 2007 } 2008 } 2009 } 2010 } 2011 2012 static void 2013 itismychild(struct witness *parent, struct witness *child) 2014 { 2015 int unlocked; 2016 2017 MPASS(child != NULL && parent != NULL); 2018 if (witness_cold == 0) 2019 mtx_assert(&w_mtx, MA_OWNED); 2020 2021 if (!witness_lock_type_equal(parent, child)) { 2022 if (witness_cold == 0) { 2023 unlocked = 1; 2024 mtx_unlock_spin(&w_mtx); 2025 } else { 2026 unlocked = 0; 2027 } 2028 kassert_panic( 2029 "%s: parent \"%s\" (%s) and child \"%s\" (%s) are not " 2030 "the same lock type", __func__, parent->w_name, 2031 parent->w_class->lc_name, child->w_name, 2032 child->w_class->lc_name); 2033 if (unlocked) 2034 mtx_lock_spin(&w_mtx); 2035 } 2036 adopt(parent, child); 2037 } 2038 2039 /* 2040 * Generic code for the isitmy*() functions. The rmask parameter is the 2041 * expected relationship of w1 to w2. 2042 */ 2043 static int 2044 _isitmyx(struct witness *w1, struct witness *w2, int rmask, const char *fname) 2045 { 2046 unsigned char r1, r2; 2047 int i1, i2; 2048 2049 i1 = w1->w_index; 2050 i2 = w2->w_index; 2051 WITNESS_INDEX_ASSERT(i1); 2052 WITNESS_INDEX_ASSERT(i2); 2053 r1 = w_rmatrix[i1][i2] & WITNESS_RELATED_MASK; 2054 r2 = w_rmatrix[i2][i1] & WITNESS_RELATED_MASK; 2055 2056 /* The flags on one better be the inverse of the flags on the other */ 2057 if (!((WITNESS_ATOD(r1) == r2 && WITNESS_DTOA(r2) == r1) || 2058 (WITNESS_DTOA(r1) == r2 && WITNESS_ATOD(r2) == r1))) { 2059 /* Don't squawk if we're potentially racing with an update. */ 2060 if (!mtx_owned(&w_mtx)) 2061 return (0); 2062 printf("%s: rmatrix mismatch between %s (index %d) and %s " 2063 "(index %d): w_rmatrix[%d][%d] == %hhx but " 2064 "w_rmatrix[%d][%d] == %hhx\n", 2065 fname, w1->w_name, i1, w2->w_name, i2, i1, i2, r1, 2066 i2, i1, r2); 2067 kdb_backtrace(); 2068 printf("Witness disabled.\n"); 2069 witness_watch = -1; 2070 } 2071 return (r1 & rmask); 2072 } 2073 2074 /* 2075 * Checks if @child is a direct child of @parent. 2076 */ 2077 static int 2078 isitmychild(struct witness *parent, struct witness *child) 2079 { 2080 2081 return (_isitmyx(parent, child, WITNESS_PARENT, __func__)); 2082 } 2083 2084 /* 2085 * Checks if @descendant is a direct or inderect descendant of @ancestor. 2086 */ 2087 static int 2088 isitmydescendant(struct witness *ancestor, struct witness *descendant) 2089 { 2090 2091 return (_isitmyx(ancestor, descendant, WITNESS_ANCESTOR_MASK, 2092 __func__)); 2093 } 2094 2095 static int 2096 blessed(struct witness *w1, struct witness *w2) 2097 { 2098 int i; 2099 struct witness_blessed *b; 2100 2101 for (i = 0; i < nitems(blessed_list); i++) { 2102 b = &blessed_list[i]; 2103 if (strcmp(w1->w_name, b->b_lock1) == 0) { 2104 if (strcmp(w2->w_name, b->b_lock2) == 0) 2105 return (1); 2106 continue; 2107 } 2108 if (strcmp(w1->w_name, b->b_lock2) == 0) 2109 if (strcmp(w2->w_name, b->b_lock1) == 0) 2110 return (1); 2111 } 2112 return (0); 2113 } 2114 2115 static struct witness * 2116 witness_get(void) 2117 { 2118 struct witness *w; 2119 int index; 2120 2121 if (witness_cold == 0) 2122 mtx_assert(&w_mtx, MA_OWNED); 2123 2124 if (witness_watch == -1) { 2125 mtx_unlock_spin(&w_mtx); 2126 return (NULL); 2127 } 2128 if (STAILQ_EMPTY(&w_free)) { 2129 witness_watch = -1; 2130 mtx_unlock_spin(&w_mtx); 2131 printf("WITNESS: unable to allocate a new witness object\n"); 2132 return (NULL); 2133 } 2134 w = STAILQ_FIRST(&w_free); 2135 STAILQ_REMOVE_HEAD(&w_free, w_list); 2136 w_free_cnt--; 2137 index = w->w_index; 2138 MPASS(index > 0 && index == w_max_used_index+1 && 2139 index < witness_count); 2140 bzero(w, sizeof(*w)); 2141 w->w_index = index; 2142 if (index > w_max_used_index) 2143 w_max_used_index = index; 2144 return (w); 2145 } 2146 2147 static void 2148 witness_free(struct witness *w) 2149 { 2150 2151 STAILQ_INSERT_HEAD(&w_free, w, w_list); 2152 w_free_cnt++; 2153 } 2154 2155 static struct lock_list_entry * 2156 witness_lock_list_get(void) 2157 { 2158 struct lock_list_entry *lle; 2159 2160 if (witness_watch == -1) 2161 return (NULL); 2162 mtx_lock_spin(&w_mtx); 2163 lle = w_lock_list_free; 2164 if (lle == NULL) { 2165 witness_watch = -1; 2166 mtx_unlock_spin(&w_mtx); 2167 printf("%s: witness exhausted\n", __func__); 2168 return (NULL); 2169 } 2170 w_lock_list_free = lle->ll_next; 2171 mtx_unlock_spin(&w_mtx); 2172 bzero(lle, sizeof(*lle)); 2173 return (lle); 2174 } 2175 2176 static void 2177 witness_lock_list_free(struct lock_list_entry *lle) 2178 { 2179 2180 mtx_lock_spin(&w_mtx); 2181 lle->ll_next = w_lock_list_free; 2182 w_lock_list_free = lle; 2183 mtx_unlock_spin(&w_mtx); 2184 } 2185 2186 static struct lock_instance * 2187 find_instance(struct lock_list_entry *list, const struct lock_object *lock) 2188 { 2189 struct lock_list_entry *lle; 2190 struct lock_instance *instance; 2191 int i; 2192 2193 for (lle = list; lle != NULL; lle = lle->ll_next) 2194 for (i = lle->ll_count - 1; i >= 0; i--) { 2195 instance = &lle->ll_children[i]; 2196 if (instance->li_lock == lock) 2197 return (instance); 2198 } 2199 return (NULL); 2200 } 2201 2202 static void 2203 witness_list_lock(struct lock_instance *instance, 2204 int (*prnt)(const char *fmt, ...)) 2205 { 2206 struct lock_object *lock; 2207 2208 lock = instance->li_lock; 2209 prnt("%s %s %s", (instance->li_flags & LI_EXCLUSIVE) != 0 ? 2210 "exclusive" : "shared", LOCK_CLASS(lock)->lc_name, lock->lo_name); 2211 if (lock->lo_witness->w_name != lock->lo_name) 2212 prnt(" (%s)", lock->lo_witness->w_name); 2213 prnt(" r = %d (%p) locked @ %s:%d\n", 2214 instance->li_flags & LI_RECURSEMASK, lock, 2215 fixup_filename(instance->li_file), instance->li_line); 2216 } 2217 2218 static int 2219 witness_output(const char *fmt, ...) 2220 { 2221 va_list ap; 2222 int ret; 2223 2224 va_start(ap, fmt); 2225 ret = witness_voutput(fmt, ap); 2226 va_end(ap); 2227 return (ret); 2228 } 2229 2230 static int 2231 witness_voutput(const char *fmt, va_list ap) 2232 { 2233 int ret; 2234 2235 ret = 0; 2236 switch (witness_channel) { 2237 case WITNESS_CONSOLE: 2238 ret = vprintf(fmt, ap); 2239 break; 2240 case WITNESS_LOG: 2241 vlog(LOG_NOTICE, fmt, ap); 2242 break; 2243 case WITNESS_NONE: 2244 break; 2245 } 2246 return (ret); 2247 } 2248 2249 #ifdef DDB 2250 static int 2251 witness_thread_has_locks(struct thread *td) 2252 { 2253 2254 if (td->td_sleeplocks == NULL) 2255 return (0); 2256 return (td->td_sleeplocks->ll_count != 0); 2257 } 2258 2259 static int 2260 witness_proc_has_locks(struct proc *p) 2261 { 2262 struct thread *td; 2263 2264 FOREACH_THREAD_IN_PROC(p, td) { 2265 if (witness_thread_has_locks(td)) 2266 return (1); 2267 } 2268 return (0); 2269 } 2270 #endif 2271 2272 int 2273 witness_list_locks(struct lock_list_entry **lock_list, 2274 int (*prnt)(const char *fmt, ...)) 2275 { 2276 struct lock_list_entry *lle; 2277 int i, nheld; 2278 2279 nheld = 0; 2280 for (lle = *lock_list; lle != NULL; lle = lle->ll_next) 2281 for (i = lle->ll_count - 1; i >= 0; i--) { 2282 witness_list_lock(&lle->ll_children[i], prnt); 2283 nheld++; 2284 } 2285 return (nheld); 2286 } 2287 2288 /* 2289 * This is a bit risky at best. We call this function when we have timed 2290 * out acquiring a spin lock, and we assume that the other CPU is stuck 2291 * with this lock held. So, we go groveling around in the other CPU's 2292 * per-cpu data to try to find the lock instance for this spin lock to 2293 * see when it was last acquired. 2294 */ 2295 void 2296 witness_display_spinlock(struct lock_object *lock, struct thread *owner, 2297 int (*prnt)(const char *fmt, ...)) 2298 { 2299 struct lock_instance *instance; 2300 struct pcpu *pc; 2301 2302 if (owner->td_critnest == 0 || owner->td_oncpu == NOCPU) 2303 return; 2304 pc = pcpu_find(owner->td_oncpu); 2305 instance = find_instance(pc->pc_spinlocks, lock); 2306 if (instance != NULL) 2307 witness_list_lock(instance, prnt); 2308 } 2309 2310 void 2311 witness_save(struct lock_object *lock, const char **filep, int *linep) 2312 { 2313 struct lock_list_entry *lock_list; 2314 struct lock_instance *instance; 2315 struct lock_class *class; 2316 2317 /* 2318 * This function is used independently in locking code to deal with 2319 * Giant, SCHEDULER_STOPPED() check can be removed here after Giant 2320 * is gone. 2321 */ 2322 if (SCHEDULER_STOPPED()) 2323 return; 2324 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); 2325 if (lock->lo_witness == NULL || witness_watch == -1 || KERNEL_PANICKED()) 2326 return; 2327 class = LOCK_CLASS(lock); 2328 if (class->lc_flags & LC_SLEEPLOCK) 2329 lock_list = curthread->td_sleeplocks; 2330 else { 2331 if (witness_skipspin) 2332 return; 2333 lock_list = PCPU_GET(spinlocks); 2334 } 2335 instance = find_instance(lock_list, lock); 2336 if (instance == NULL) { 2337 kassert_panic("%s: lock (%s) %s not locked", __func__, 2338 class->lc_name, lock->lo_name); 2339 return; 2340 } 2341 *filep = instance->li_file; 2342 *linep = instance->li_line; 2343 } 2344 2345 void 2346 witness_restore(struct lock_object *lock, const char *file, int line) 2347 { 2348 struct lock_list_entry *lock_list; 2349 struct lock_instance *instance; 2350 struct lock_class *class; 2351 2352 /* 2353 * This function is used independently in locking code to deal with 2354 * Giant, SCHEDULER_STOPPED() check can be removed here after Giant 2355 * is gone. 2356 */ 2357 if (SCHEDULER_STOPPED()) 2358 return; 2359 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); 2360 if (lock->lo_witness == NULL || witness_watch == -1 || KERNEL_PANICKED()) 2361 return; 2362 class = LOCK_CLASS(lock); 2363 if (class->lc_flags & LC_SLEEPLOCK) 2364 lock_list = curthread->td_sleeplocks; 2365 else { 2366 if (witness_skipspin) 2367 return; 2368 lock_list = PCPU_GET(spinlocks); 2369 } 2370 instance = find_instance(lock_list, lock); 2371 if (instance == NULL) 2372 kassert_panic("%s: lock (%s) %s not locked", __func__, 2373 class->lc_name, lock->lo_name); 2374 lock->lo_witness->w_file = file; 2375 lock->lo_witness->w_line = line; 2376 if (instance == NULL) 2377 return; 2378 instance->li_file = file; 2379 instance->li_line = line; 2380 } 2381 2382 void 2383 witness_assert(const struct lock_object *lock, int flags, const char *file, 2384 int line) 2385 { 2386 #ifdef INVARIANT_SUPPORT 2387 struct lock_instance *instance; 2388 struct lock_class *class; 2389 2390 if (lock->lo_witness == NULL || witness_watch < 1 || KERNEL_PANICKED()) 2391 return; 2392 class = LOCK_CLASS(lock); 2393 if ((class->lc_flags & LC_SLEEPLOCK) != 0) 2394 instance = find_instance(curthread->td_sleeplocks, lock); 2395 else if ((class->lc_flags & LC_SPINLOCK) != 0) 2396 instance = find_instance(PCPU_GET(spinlocks), lock); 2397 else { 2398 kassert_panic("Lock (%s) %s is not sleep or spin!", 2399 class->lc_name, lock->lo_name); 2400 return; 2401 } 2402 switch (flags) { 2403 case LA_UNLOCKED: 2404 if (instance != NULL) 2405 kassert_panic("Lock (%s) %s locked @ %s:%d.", 2406 class->lc_name, lock->lo_name, 2407 fixup_filename(file), line); 2408 break; 2409 case LA_LOCKED: 2410 case LA_LOCKED | LA_RECURSED: 2411 case LA_LOCKED | LA_NOTRECURSED: 2412 case LA_SLOCKED: 2413 case LA_SLOCKED | LA_RECURSED: 2414 case LA_SLOCKED | LA_NOTRECURSED: 2415 case LA_XLOCKED: 2416 case LA_XLOCKED | LA_RECURSED: 2417 case LA_XLOCKED | LA_NOTRECURSED: 2418 if (instance == NULL) { 2419 kassert_panic("Lock (%s) %s not locked @ %s:%d.", 2420 class->lc_name, lock->lo_name, 2421 fixup_filename(file), line); 2422 break; 2423 } 2424 if ((flags & LA_XLOCKED) != 0 && 2425 (instance->li_flags & LI_EXCLUSIVE) == 0) 2426 kassert_panic( 2427 "Lock (%s) %s not exclusively locked @ %s:%d.", 2428 class->lc_name, lock->lo_name, 2429 fixup_filename(file), line); 2430 if ((flags & LA_SLOCKED) != 0 && 2431 (instance->li_flags & LI_EXCLUSIVE) != 0) 2432 kassert_panic( 2433 "Lock (%s) %s exclusively locked @ %s:%d.", 2434 class->lc_name, lock->lo_name, 2435 fixup_filename(file), line); 2436 if ((flags & LA_RECURSED) != 0 && 2437 (instance->li_flags & LI_RECURSEMASK) == 0) 2438 kassert_panic("Lock (%s) %s not recursed @ %s:%d.", 2439 class->lc_name, lock->lo_name, 2440 fixup_filename(file), line); 2441 if ((flags & LA_NOTRECURSED) != 0 && 2442 (instance->li_flags & LI_RECURSEMASK) != 0) 2443 kassert_panic("Lock (%s) %s recursed @ %s:%d.", 2444 class->lc_name, lock->lo_name, 2445 fixup_filename(file), line); 2446 break; 2447 default: 2448 kassert_panic("Invalid lock assertion at %s:%d.", 2449 fixup_filename(file), line); 2450 2451 } 2452 #endif /* INVARIANT_SUPPORT */ 2453 } 2454 2455 static void 2456 witness_setflag(struct lock_object *lock, int flag, int set) 2457 { 2458 struct lock_list_entry *lock_list; 2459 struct lock_instance *instance; 2460 struct lock_class *class; 2461 2462 if (lock->lo_witness == NULL || witness_watch == -1 || KERNEL_PANICKED()) 2463 return; 2464 class = LOCK_CLASS(lock); 2465 if (class->lc_flags & LC_SLEEPLOCK) 2466 lock_list = curthread->td_sleeplocks; 2467 else { 2468 if (witness_skipspin) 2469 return; 2470 lock_list = PCPU_GET(spinlocks); 2471 } 2472 instance = find_instance(lock_list, lock); 2473 if (instance == NULL) { 2474 kassert_panic("%s: lock (%s) %s not locked", __func__, 2475 class->lc_name, lock->lo_name); 2476 return; 2477 } 2478 2479 if (set) 2480 instance->li_flags |= flag; 2481 else 2482 instance->li_flags &= ~flag; 2483 } 2484 2485 void 2486 witness_norelease(struct lock_object *lock) 2487 { 2488 2489 witness_setflag(lock, LI_NORELEASE, 1); 2490 } 2491 2492 void 2493 witness_releaseok(struct lock_object *lock) 2494 { 2495 2496 witness_setflag(lock, LI_NORELEASE, 0); 2497 } 2498 2499 #ifdef DDB 2500 static void 2501 witness_ddb_list(struct thread *td) 2502 { 2503 2504 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); 2505 KASSERT(kdb_active, ("%s: not in the debugger", __func__)); 2506 2507 if (witness_watch < 1) 2508 return; 2509 2510 witness_list_locks(&td->td_sleeplocks, db_printf); 2511 2512 /* 2513 * We only handle spinlocks if td == curthread. This is somewhat broken 2514 * if td is currently executing on some other CPU and holds spin locks 2515 * as we won't display those locks. If we had a MI way of getting 2516 * the per-cpu data for a given cpu then we could use 2517 * td->td_oncpu to get the list of spinlocks for this thread 2518 * and "fix" this. 2519 * 2520 * That still wouldn't really fix this unless we locked the scheduler 2521 * lock or stopped the other CPU to make sure it wasn't changing the 2522 * list out from under us. It is probably best to just not try to 2523 * handle threads on other CPU's for now. 2524 */ 2525 if (td == curthread && PCPU_GET(spinlocks) != NULL) 2526 witness_list_locks(PCPU_PTR(spinlocks), db_printf); 2527 } 2528 2529 DB_SHOW_COMMAND(locks, db_witness_list) 2530 { 2531 struct thread *td; 2532 2533 if (have_addr) 2534 td = db_lookup_thread(addr, true); 2535 else 2536 td = kdb_thread; 2537 witness_ddb_list(td); 2538 } 2539 2540 DB_SHOW_ALL_COMMAND(locks, db_witness_list_all) 2541 { 2542 struct thread *td; 2543 struct proc *p; 2544 2545 /* 2546 * It would be nice to list only threads and processes that actually 2547 * held sleep locks, but that information is currently not exported 2548 * by WITNESS. 2549 */ 2550 FOREACH_PROC_IN_SYSTEM(p) { 2551 if (!witness_proc_has_locks(p)) 2552 continue; 2553 FOREACH_THREAD_IN_PROC(p, td) { 2554 if (!witness_thread_has_locks(td)) 2555 continue; 2556 db_printf("Process %d (%s) thread %p (%d)\n", p->p_pid, 2557 p->p_comm, td, td->td_tid); 2558 witness_ddb_list(td); 2559 if (db_pager_quit) 2560 return; 2561 } 2562 } 2563 } 2564 DB_SHOW_ALIAS(alllocks, db_witness_list_all) 2565 2566 DB_SHOW_COMMAND(witness, db_witness_display) 2567 { 2568 2569 witness_ddb_display(db_printf); 2570 } 2571 #endif 2572 2573 static void 2574 sbuf_print_witness_badstacks(struct sbuf *sb, size_t *oldidx) 2575 { 2576 struct witness_lock_order_data *data1, *data2, *tmp_data1, *tmp_data2; 2577 struct witness *tmp_w1, *tmp_w2, *w1, *w2; 2578 int generation, i, j; 2579 2580 tmp_data1 = NULL; 2581 tmp_data2 = NULL; 2582 tmp_w1 = NULL; 2583 tmp_w2 = NULL; 2584 2585 /* Allocate and init temporary storage space. */ 2586 tmp_w1 = malloc(sizeof(struct witness), M_TEMP, M_WAITOK | M_ZERO); 2587 tmp_w2 = malloc(sizeof(struct witness), M_TEMP, M_WAITOK | M_ZERO); 2588 tmp_data1 = malloc(sizeof(struct witness_lock_order_data), M_TEMP, 2589 M_WAITOK | M_ZERO); 2590 tmp_data2 = malloc(sizeof(struct witness_lock_order_data), M_TEMP, 2591 M_WAITOK | M_ZERO); 2592 stack_zero(&tmp_data1->wlod_stack); 2593 stack_zero(&tmp_data2->wlod_stack); 2594 2595 restart: 2596 mtx_lock_spin(&w_mtx); 2597 generation = w_generation; 2598 mtx_unlock_spin(&w_mtx); 2599 sbuf_printf(sb, "Number of known direct relationships is %d\n", 2600 w_lohash.wloh_count); 2601 for (i = 1; i < w_max_used_index; i++) { 2602 mtx_lock_spin(&w_mtx); 2603 if (generation != w_generation) { 2604 mtx_unlock_spin(&w_mtx); 2605 2606 /* The graph has changed, try again. */ 2607 *oldidx = 0; 2608 sbuf_clear(sb); 2609 goto restart; 2610 } 2611 2612 w1 = &w_data[i]; 2613 if (w1->w_reversed == 0) { 2614 mtx_unlock_spin(&w_mtx); 2615 continue; 2616 } 2617 2618 /* Copy w1 locally so we can release the spin lock. */ 2619 *tmp_w1 = *w1; 2620 mtx_unlock_spin(&w_mtx); 2621 2622 if (tmp_w1->w_reversed == 0) 2623 continue; 2624 for (j = 1; j < w_max_used_index; j++) { 2625 if ((w_rmatrix[i][j] & WITNESS_REVERSAL) == 0 || i > j) 2626 continue; 2627 2628 mtx_lock_spin(&w_mtx); 2629 if (generation != w_generation) { 2630 mtx_unlock_spin(&w_mtx); 2631 2632 /* The graph has changed, try again. */ 2633 *oldidx = 0; 2634 sbuf_clear(sb); 2635 goto restart; 2636 } 2637 2638 w2 = &w_data[j]; 2639 data1 = witness_lock_order_get(w1, w2); 2640 data2 = witness_lock_order_get(w2, w1); 2641 2642 /* 2643 * Copy information locally so we can release the 2644 * spin lock. 2645 */ 2646 *tmp_w2 = *w2; 2647 2648 if (data1) { 2649 stack_zero(&tmp_data1->wlod_stack); 2650 stack_copy(&data1->wlod_stack, 2651 &tmp_data1->wlod_stack); 2652 } 2653 if (data2 && data2 != data1) { 2654 stack_zero(&tmp_data2->wlod_stack); 2655 stack_copy(&data2->wlod_stack, 2656 &tmp_data2->wlod_stack); 2657 } 2658 mtx_unlock_spin(&w_mtx); 2659 2660 if (blessed(tmp_w1, tmp_w2)) 2661 continue; 2662 2663 sbuf_printf(sb, 2664 "\nLock order reversal between \"%s\"(%s) and \"%s\"(%s)!\n", 2665 tmp_w1->w_name, tmp_w1->w_class->lc_name, 2666 tmp_w2->w_name, tmp_w2->w_class->lc_name); 2667 if (data1) { 2668 sbuf_printf(sb, 2669 "Lock order \"%s\"(%s) -> \"%s\"(%s) first seen at:\n", 2670 tmp_w1->w_name, tmp_w1->w_class->lc_name, 2671 tmp_w2->w_name, tmp_w2->w_class->lc_name); 2672 stack_sbuf_print(sb, &tmp_data1->wlod_stack); 2673 sbuf_printf(sb, "\n"); 2674 } 2675 if (data2 && data2 != data1) { 2676 sbuf_printf(sb, 2677 "Lock order \"%s\"(%s) -> \"%s\"(%s) first seen at:\n", 2678 tmp_w2->w_name, tmp_w2->w_class->lc_name, 2679 tmp_w1->w_name, tmp_w1->w_class->lc_name); 2680 stack_sbuf_print(sb, &tmp_data2->wlod_stack); 2681 sbuf_printf(sb, "\n"); 2682 } 2683 } 2684 } 2685 mtx_lock_spin(&w_mtx); 2686 if (generation != w_generation) { 2687 mtx_unlock_spin(&w_mtx); 2688 2689 /* 2690 * The graph changed while we were printing stack data, 2691 * try again. 2692 */ 2693 *oldidx = 0; 2694 sbuf_clear(sb); 2695 goto restart; 2696 } 2697 mtx_unlock_spin(&w_mtx); 2698 2699 /* Free temporary storage space. */ 2700 free(tmp_data1, M_TEMP); 2701 free(tmp_data2, M_TEMP); 2702 free(tmp_w1, M_TEMP); 2703 free(tmp_w2, M_TEMP); 2704 } 2705 2706 static int 2707 sysctl_debug_witness_badstacks(SYSCTL_HANDLER_ARGS) 2708 { 2709 struct sbuf *sb; 2710 int error; 2711 2712 if (witness_watch < 1) { 2713 error = SYSCTL_OUT(req, w_notrunning, sizeof(w_notrunning)); 2714 return (error); 2715 } 2716 if (witness_cold) { 2717 error = SYSCTL_OUT(req, w_stillcold, sizeof(w_stillcold)); 2718 return (error); 2719 } 2720 error = 0; 2721 sb = sbuf_new(NULL, NULL, badstack_sbuf_size, SBUF_AUTOEXTEND); 2722 if (sb == NULL) 2723 return (ENOMEM); 2724 2725 sbuf_print_witness_badstacks(sb, &req->oldidx); 2726 2727 sbuf_finish(sb); 2728 error = SYSCTL_OUT(req, sbuf_data(sb), sbuf_len(sb) + 1); 2729 sbuf_delete(sb); 2730 2731 return (error); 2732 } 2733 2734 #ifdef DDB 2735 static int 2736 sbuf_db_printf_drain(void *arg __unused, const char *data, int len) 2737 { 2738 2739 return (db_printf("%.*s", len, data)); 2740 } 2741 2742 DB_SHOW_COMMAND(badstacks, db_witness_badstacks) 2743 { 2744 struct sbuf sb; 2745 char buffer[128]; 2746 size_t dummy; 2747 2748 sbuf_new(&sb, buffer, sizeof(buffer), SBUF_FIXEDLEN); 2749 sbuf_set_drain(&sb, sbuf_db_printf_drain, NULL); 2750 sbuf_print_witness_badstacks(&sb, &dummy); 2751 sbuf_finish(&sb); 2752 } 2753 #endif 2754 2755 static int 2756 sysctl_debug_witness_channel(SYSCTL_HANDLER_ARGS) 2757 { 2758 static const struct { 2759 enum witness_channel channel; 2760 const char *name; 2761 } channels[] = { 2762 { WITNESS_CONSOLE, "console" }, 2763 { WITNESS_LOG, "log" }, 2764 { WITNESS_NONE, "none" }, 2765 }; 2766 char buf[16]; 2767 u_int i; 2768 int error; 2769 2770 buf[0] = '\0'; 2771 for (i = 0; i < nitems(channels); i++) 2772 if (witness_channel == channels[i].channel) { 2773 snprintf(buf, sizeof(buf), "%s", channels[i].name); 2774 break; 2775 } 2776 2777 error = sysctl_handle_string(oidp, buf, sizeof(buf), req); 2778 if (error != 0 || req->newptr == NULL) 2779 return (error); 2780 2781 error = EINVAL; 2782 for (i = 0; i < nitems(channels); i++) 2783 if (strcmp(channels[i].name, buf) == 0) { 2784 witness_channel = channels[i].channel; 2785 error = 0; 2786 break; 2787 } 2788 return (error); 2789 } 2790 2791 static int 2792 sysctl_debug_witness_fullgraph(SYSCTL_HANDLER_ARGS) 2793 { 2794 struct witness *w; 2795 struct sbuf *sb; 2796 int error; 2797 2798 #ifdef __i386__ 2799 error = SYSCTL_OUT(req, w_notallowed, sizeof(w_notallowed)); 2800 return (error); 2801 #endif 2802 2803 if (witness_watch < 1) { 2804 error = SYSCTL_OUT(req, w_notrunning, sizeof(w_notrunning)); 2805 return (error); 2806 } 2807 if (witness_cold) { 2808 error = SYSCTL_OUT(req, w_stillcold, sizeof(w_stillcold)); 2809 return (error); 2810 } 2811 error = 0; 2812 2813 error = sysctl_wire_old_buffer(req, 0); 2814 if (error != 0) 2815 return (error); 2816 sb = sbuf_new_for_sysctl(NULL, NULL, FULLGRAPH_SBUF_SIZE, req); 2817 if (sb == NULL) 2818 return (ENOMEM); 2819 sbuf_printf(sb, "\n"); 2820 2821 mtx_lock_spin(&w_mtx); 2822 STAILQ_FOREACH(w, &w_all, w_list) 2823 w->w_displayed = 0; 2824 STAILQ_FOREACH(w, &w_all, w_list) 2825 witness_add_fullgraph(sb, w); 2826 mtx_unlock_spin(&w_mtx); 2827 2828 /* 2829 * Close the sbuf and return to userland. 2830 */ 2831 error = sbuf_finish(sb); 2832 sbuf_delete(sb); 2833 2834 return (error); 2835 } 2836 2837 static int 2838 sysctl_debug_witness_watch(SYSCTL_HANDLER_ARGS) 2839 { 2840 int error, value; 2841 2842 value = witness_watch; 2843 error = sysctl_handle_int(oidp, &value, 0, req); 2844 if (error != 0 || req->newptr == NULL) 2845 return (error); 2846 if (value > 1 || value < -1 || 2847 (witness_watch == -1 && value != witness_watch)) 2848 return (EINVAL); 2849 witness_watch = value; 2850 return (0); 2851 } 2852 2853 static void 2854 witness_add_fullgraph(struct sbuf *sb, struct witness *w) 2855 { 2856 int i; 2857 2858 if (w->w_displayed != 0 || (w->w_file == NULL && w->w_line == 0)) 2859 return; 2860 w->w_displayed = 1; 2861 2862 WITNESS_INDEX_ASSERT(w->w_index); 2863 for (i = 1; i <= w_max_used_index; i++) { 2864 if (w_rmatrix[w->w_index][i] & WITNESS_PARENT) { 2865 sbuf_printf(sb, "\"%s\",\"%s\"\n", w->w_name, 2866 w_data[i].w_name); 2867 witness_add_fullgraph(sb, &w_data[i]); 2868 } 2869 } 2870 } 2871 2872 /* 2873 * A simple hash function. Takes a key pointer and a key size. If size == 0, 2874 * interprets the key as a string and reads until the null 2875 * terminator. Otherwise, reads the first size bytes. Returns an unsigned 32-bit 2876 * hash value computed from the key. 2877 */ 2878 static uint32_t 2879 witness_hash_djb2(const uint8_t *key, uint32_t size) 2880 { 2881 unsigned int hash = 5381; 2882 int i; 2883 2884 /* hash = hash * 33 + key[i] */ 2885 if (size) 2886 for (i = 0; i < size; i++) 2887 hash = ((hash << 5) + hash) + (unsigned int)key[i]; 2888 else 2889 for (i = 0; key[i] != 0; i++) 2890 hash = ((hash << 5) + hash) + (unsigned int)key[i]; 2891 2892 return (hash); 2893 } 2894 2895 /* 2896 * Initializes the two witness hash tables. Called exactly once from 2897 * witness_initialize(). 2898 */ 2899 static void 2900 witness_init_hash_tables(void) 2901 { 2902 int i; 2903 2904 MPASS(witness_cold); 2905 2906 /* Initialize the hash tables. */ 2907 for (i = 0; i < WITNESS_HASH_SIZE; i++) 2908 w_hash.wh_array[i] = NULL; 2909 2910 w_hash.wh_size = WITNESS_HASH_SIZE; 2911 w_hash.wh_count = 0; 2912 2913 /* Initialize the lock order data hash. */ 2914 w_lofree = NULL; 2915 for (i = 0; i < WITNESS_LO_DATA_COUNT; i++) { 2916 memset(&w_lodata[i], 0, sizeof(w_lodata[i])); 2917 w_lodata[i].wlod_next = w_lofree; 2918 w_lofree = &w_lodata[i]; 2919 } 2920 w_lohash.wloh_size = WITNESS_LO_HASH_SIZE; 2921 w_lohash.wloh_count = 0; 2922 for (i = 0; i < WITNESS_LO_HASH_SIZE; i++) 2923 w_lohash.wloh_array[i] = NULL; 2924 } 2925 2926 static struct witness * 2927 witness_hash_get(const char *key) 2928 { 2929 struct witness *w; 2930 uint32_t hash; 2931 2932 MPASS(key != NULL); 2933 if (witness_cold == 0) 2934 mtx_assert(&w_mtx, MA_OWNED); 2935 hash = witness_hash_djb2(key, 0) % w_hash.wh_size; 2936 w = w_hash.wh_array[hash]; 2937 while (w != NULL) { 2938 if (strcmp(w->w_name, key) == 0) 2939 goto out; 2940 w = w->w_hash_next; 2941 } 2942 2943 out: 2944 return (w); 2945 } 2946 2947 static void 2948 witness_hash_put(struct witness *w) 2949 { 2950 uint32_t hash; 2951 2952 MPASS(w != NULL); 2953 MPASS(w->w_name != NULL); 2954 if (witness_cold == 0) 2955 mtx_assert(&w_mtx, MA_OWNED); 2956 KASSERT(witness_hash_get(w->w_name) == NULL, 2957 ("%s: trying to add a hash entry that already exists!", __func__)); 2958 KASSERT(w->w_hash_next == NULL, 2959 ("%s: w->w_hash_next != NULL", __func__)); 2960 2961 hash = witness_hash_djb2(w->w_name, 0) % w_hash.wh_size; 2962 w->w_hash_next = w_hash.wh_array[hash]; 2963 w_hash.wh_array[hash] = w; 2964 w_hash.wh_count++; 2965 } 2966 2967 static struct witness_lock_order_data * 2968 witness_lock_order_get(struct witness *parent, struct witness *child) 2969 { 2970 struct witness_lock_order_data *data = NULL; 2971 struct witness_lock_order_key key; 2972 unsigned int hash; 2973 2974 MPASS(parent != NULL && child != NULL); 2975 key.from = parent->w_index; 2976 key.to = child->w_index; 2977 WITNESS_INDEX_ASSERT(key.from); 2978 WITNESS_INDEX_ASSERT(key.to); 2979 if ((w_rmatrix[parent->w_index][child->w_index] 2980 & WITNESS_LOCK_ORDER_KNOWN) == 0) 2981 goto out; 2982 2983 hash = witness_hash_djb2((const char*)&key, 2984 sizeof(key)) % w_lohash.wloh_size; 2985 data = w_lohash.wloh_array[hash]; 2986 while (data != NULL) { 2987 if (witness_lock_order_key_equal(&data->wlod_key, &key)) 2988 break; 2989 data = data->wlod_next; 2990 } 2991 2992 out: 2993 return (data); 2994 } 2995 2996 /* 2997 * Verify that parent and child have a known relationship, are not the same, 2998 * and child is actually a child of parent. This is done without w_mtx 2999 * to avoid contention in the common case. 3000 */ 3001 static int 3002 witness_lock_order_check(struct witness *parent, struct witness *child) 3003 { 3004 3005 if (parent != child && 3006 w_rmatrix[parent->w_index][child->w_index] 3007 & WITNESS_LOCK_ORDER_KNOWN && 3008 isitmychild(parent, child)) 3009 return (1); 3010 3011 return (0); 3012 } 3013 3014 static int 3015 witness_lock_order_add(struct witness *parent, struct witness *child) 3016 { 3017 struct witness_lock_order_data *data = NULL; 3018 struct witness_lock_order_key key; 3019 unsigned int hash; 3020 3021 MPASS(parent != NULL && child != NULL); 3022 key.from = parent->w_index; 3023 key.to = child->w_index; 3024 WITNESS_INDEX_ASSERT(key.from); 3025 WITNESS_INDEX_ASSERT(key.to); 3026 if (w_rmatrix[parent->w_index][child->w_index] 3027 & WITNESS_LOCK_ORDER_KNOWN) 3028 return (1); 3029 3030 hash = witness_hash_djb2((const char*)&key, 3031 sizeof(key)) % w_lohash.wloh_size; 3032 w_rmatrix[parent->w_index][child->w_index] |= WITNESS_LOCK_ORDER_KNOWN; 3033 data = w_lofree; 3034 if (data == NULL) 3035 return (0); 3036 w_lofree = data->wlod_next; 3037 data->wlod_next = w_lohash.wloh_array[hash]; 3038 data->wlod_key = key; 3039 w_lohash.wloh_array[hash] = data; 3040 w_lohash.wloh_count++; 3041 stack_zero(&data->wlod_stack); 3042 stack_save(&data->wlod_stack); 3043 return (1); 3044 } 3045 3046 /* Call this whenever the structure of the witness graph changes. */ 3047 static void 3048 witness_increment_graph_generation(void) 3049 { 3050 3051 if (witness_cold == 0) 3052 mtx_assert(&w_mtx, MA_OWNED); 3053 w_generation++; 3054 } 3055 3056 static int 3057 witness_output_drain(void *arg __unused, const char *data, int len) 3058 { 3059 3060 witness_output("%.*s", len, data); 3061 return (len); 3062 } 3063 3064 static void 3065 witness_debugger(int cond, const char *msg) 3066 { 3067 char buf[32]; 3068 struct sbuf sb; 3069 struct stack st; 3070 3071 if (!cond) 3072 return; 3073 3074 if (witness_trace) { 3075 sbuf_new(&sb, buf, sizeof(buf), SBUF_FIXEDLEN); 3076 sbuf_set_drain(&sb, witness_output_drain, NULL); 3077 3078 stack_zero(&st); 3079 stack_save(&st); 3080 witness_output("stack backtrace:\n"); 3081 stack_sbuf_print_ddb(&sb, &st); 3082 3083 sbuf_finish(&sb); 3084 } 3085 3086 #ifdef KDB 3087 if (witness_kdb) 3088 kdb_enter(KDB_WHY_WITNESS, msg); 3089 #endif 3090 } 3091