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 #include "opt_ddb.h" 91 #include "opt_hwpmc_hooks.h" 92 #include "opt_stack.h" 93 #include "opt_witness.h" 94 95 #include <sys/param.h> 96 #include <sys/bus.h> 97 #include <sys/kdb.h> 98 #include <sys/kernel.h> 99 #include <sys/ktr.h> 100 #include <sys/lock.h> 101 #include <sys/malloc.h> 102 #include <sys/mutex.h> 103 #include <sys/priv.h> 104 #include <sys/proc.h> 105 #include <sys/sbuf.h> 106 #include <sys/sched.h> 107 #include <sys/stack.h> 108 #include <sys/stdarg.h> 109 #include <sys/sysctl.h> 110 #include <sys/syslog.h> 111 #include <sys/systm.h> 112 113 #ifdef DDB 114 #include <ddb/ddb.h> 115 #endif 116 117 #if !defined(DDB) && !defined(STACK) 118 #error "DDB or STACK options are required for WITNESS" 119 #endif 120 121 /* Note that these traces do not work with KTR_ALQ. */ 122 #if 0 123 #define KTR_WITNESS KTR_SUBSYS 124 #else 125 #define KTR_WITNESS 0 126 #endif 127 128 #define LI_RECURSEMASK 0x0000ffff /* Recursion depth of lock instance. */ 129 #define LI_EXCLUSIVE 0x00010000 /* Exclusive lock instance. */ 130 #define LI_NORELEASE 0x00020000 /* Lock not allowed to be released. */ 131 #define LI_SLEEPABLE 0x00040000 /* Lock may be held while sleeping. */ 132 133 #ifndef WITNESS_COUNT 134 #define WITNESS_COUNT 1536 135 #endif 136 #define WITNESS_HASH_SIZE 251 /* Prime, gives load factor < 2 */ 137 #define WITNESS_PENDLIST (512 + (MAXCPU * 4)) 138 139 /* Allocate 256 KB of stack data space */ 140 #define WITNESS_LO_DATA_COUNT 2048 141 142 /* Prime, gives load factor of ~2 at full load */ 143 #define WITNESS_LO_HASH_SIZE 1021 144 145 /* 146 * XXX: This is somewhat bogus, as we assume here that at most 2048 threads 147 * will hold LOCK_NCHILDREN locks. We handle failure ok, and we should 148 * probably be safe for the most part, but it's still a SWAG. 149 */ 150 #define LOCK_NCHILDREN 5 151 #define LOCK_CHILDCOUNT 2048 152 153 #define MAX_W_NAME 64 154 155 #define FULLGRAPH_SBUF_SIZE 512 156 157 /* 158 * These flags go in the witness relationship matrix and describe the 159 * relationship between any two struct witness objects. 160 */ 161 #define WITNESS_UNRELATED 0x00 /* No lock order relation. */ 162 #define WITNESS_PARENT 0x01 /* Parent, aka direct ancestor. */ 163 #define WITNESS_ANCESTOR 0x02 /* Direct or indirect ancestor. */ 164 #define WITNESS_CHILD 0x04 /* Child, aka direct descendant. */ 165 #define WITNESS_DESCENDANT 0x08 /* Direct or indirect descendant. */ 166 #define WITNESS_ANCESTOR_MASK (WITNESS_PARENT | WITNESS_ANCESTOR) 167 #define WITNESS_DESCENDANT_MASK (WITNESS_CHILD | WITNESS_DESCENDANT) 168 #define WITNESS_RELATED_MASK \ 169 (WITNESS_ANCESTOR_MASK | WITNESS_DESCENDANT_MASK) 170 #define WITNESS_REVERSAL 0x10 /* A lock order reversal has been 171 * observed. */ 172 #define WITNESS_RESERVED1 0x20 /* Unused flag, reserved. */ 173 #define WITNESS_RESERVED2 0x40 /* Unused flag, reserved. */ 174 #define WITNESS_LOCK_ORDER_KNOWN 0x80 /* This lock order is known. */ 175 176 /* Descendant to ancestor flags */ 177 #define WITNESS_DTOA(x) (((x) & WITNESS_RELATED_MASK) >> 2) 178 179 /* Ancestor to descendant flags */ 180 #define WITNESS_ATOD(x) (((x) & WITNESS_RELATED_MASK) << 2) 181 182 #define WITNESS_INDEX_ASSERT(i) \ 183 MPASS((i) > 0 && (i) <= w_max_used_index && (i) < witness_count) 184 185 static MALLOC_DEFINE(M_WITNESS, "Witness", "Witness"); 186 187 /* 188 * Lock instances. A lock instance is the data associated with a lock while 189 * it is held by witness. For example, a lock instance will hold the 190 * recursion count of a lock. Lock instances are held in lists. Spin locks 191 * are held in a per-cpu list while sleep locks are held in per-thread list. 192 */ 193 struct lock_instance { 194 struct lock_object *li_lock; 195 const char *li_file; 196 int li_line; 197 u_int li_flags; 198 }; 199 200 /* 201 * A simple list type used to build the list of locks held by a thread 202 * or CPU. We can't simply embed the list in struct lock_object since a 203 * lock may be held by more than one thread if it is a shared lock. Locks 204 * are added to the head of the list, so we fill up each list entry from 205 * "the back" logically. To ease some of the arithmetic, we actually fill 206 * in each list entry the normal way (children[0] then children[1], etc.) but 207 * when we traverse the list we read children[count-1] as the first entry 208 * down to children[0] as the final entry. 209 */ 210 struct lock_list_entry { 211 struct lock_list_entry *ll_next; 212 struct lock_instance ll_children[LOCK_NCHILDREN]; 213 u_int ll_count; 214 }; 215 216 /* 217 * The main witness structure. One of these per named lock type in the system 218 * (for example, "vnode interlock"). 219 */ 220 struct witness { 221 char w_name[MAX_W_NAME]; 222 uint32_t w_index; /* Index in the relationship matrix */ 223 struct lock_class *w_class; 224 STAILQ_ENTRY(witness) w_list; /* List of all witnesses. */ 225 STAILQ_ENTRY(witness) w_typelist; /* Witnesses of a type. */ 226 struct witness *w_hash_next; /* Linked list in hash buckets. */ 227 const char *w_file; /* File where last acquired */ 228 uint32_t w_line; /* Line where last acquired */ 229 uint32_t w_refcount; 230 uint16_t w_num_ancestors; /* direct/indirect 231 * ancestor count */ 232 uint16_t w_num_descendants; /* direct/indirect 233 * descendant count */ 234 int16_t w_ddb_level; 235 unsigned w_displayed:1; 236 unsigned w_reversed:1; 237 }; 238 239 STAILQ_HEAD(witness_list, witness); 240 241 /* 242 * The witness hash table. Keys are witness names (const char *), elements are 243 * witness objects (struct witness *). 244 */ 245 struct witness_hash { 246 struct witness *wh_array[WITNESS_HASH_SIZE]; 247 uint32_t wh_size; 248 uint32_t wh_count; 249 }; 250 251 /* 252 * Key type for the lock order data hash table. 253 */ 254 struct witness_lock_order_key { 255 uint16_t from; 256 uint16_t to; 257 }; 258 259 struct witness_lock_order_data { 260 struct stack wlod_stack; 261 struct witness_lock_order_key wlod_key; 262 struct witness_lock_order_data *wlod_next; 263 }; 264 265 /* 266 * The witness lock order data hash table. Keys are witness index tuples 267 * (struct witness_lock_order_key), elements are lock order data objects 268 * (struct witness_lock_order_data). 269 */ 270 struct witness_lock_order_hash { 271 struct witness_lock_order_data *wloh_array[WITNESS_LO_HASH_SIZE]; 272 u_int wloh_size; 273 u_int wloh_count; 274 }; 275 276 struct witness_blessed { 277 const char *b_lock1; 278 const char *b_lock2; 279 }; 280 281 struct witness_pendhelp { 282 const char *wh_type; 283 struct lock_object *wh_lock; 284 }; 285 286 struct witness_order_list_entry { 287 const char *w_name; 288 struct lock_class *w_class; 289 }; 290 291 /* 292 * Returns 0 if one of the locks is a spin lock and the other is not. 293 * Returns 1 otherwise. 294 */ 295 static __inline int 296 witness_lock_type_equal(struct witness *w1, struct witness *w2) 297 { 298 299 return ((w1->w_class->lc_flags & (LC_SLEEPLOCK | LC_SPINLOCK)) == 300 (w2->w_class->lc_flags & (LC_SLEEPLOCK | LC_SPINLOCK))); 301 } 302 303 static __inline int 304 witness_lock_order_key_equal(const struct witness_lock_order_key *a, 305 const struct witness_lock_order_key *b) 306 { 307 308 return (a->from == b->from && a->to == b->to); 309 } 310 311 static int _isitmyx(struct witness *w1, struct witness *w2, int rmask, 312 const char *fname); 313 static void adopt(struct witness *parent, struct witness *child); 314 static int blessed(struct witness *, struct witness *); 315 static void depart(struct witness *w); 316 static struct witness *enroll(const char *description, 317 struct lock_class *lock_class); 318 static struct lock_instance *find_instance(struct lock_list_entry *list, 319 const struct lock_object *lock); 320 static int isitmychild(struct witness *parent, struct witness *child); 321 static int isitmydescendant(struct witness *parent, struct witness *child); 322 static void itismychild(struct witness *parent, struct witness *child); 323 static int sysctl_debug_witness_badstacks(SYSCTL_HANDLER_ARGS); 324 static int sysctl_debug_witness_watch(SYSCTL_HANDLER_ARGS); 325 static int sysctl_debug_witness_fullgraph(SYSCTL_HANDLER_ARGS); 326 static int sysctl_debug_witness_channel(SYSCTL_HANDLER_ARGS); 327 static void witness_add_fullgraph(struct sbuf *sb, struct witness *parent); 328 #ifdef DDB 329 static void witness_ddb_compute_levels(void); 330 static void witness_ddb_display(int(*)(const char *fmt, ...)); 331 static void witness_ddb_display_descendants(int(*)(const char *fmt, ...), 332 struct witness *, int indent); 333 static void witness_ddb_display_list(int(*prnt)(const char *fmt, ...), 334 struct witness_list *list); 335 static void witness_ddb_level_descendants(struct witness *parent, int l); 336 static void witness_ddb_list(struct thread *td); 337 #endif 338 static void witness_enter_debugger(const char *msg); 339 static void witness_debugger(int cond, const char *msg); 340 static void witness_free(struct witness *m); 341 static struct witness *witness_get(void); 342 static uint32_t witness_hash_djb2(const uint8_t *key, uint32_t size); 343 static struct witness *witness_hash_get(const char *key); 344 static void witness_hash_put(struct witness *w); 345 static void witness_init_hash_tables(void); 346 static void witness_increment_graph_generation(void); 347 static void witness_lock_list_free(struct lock_list_entry *lle); 348 static struct lock_list_entry *witness_lock_list_get(void); 349 static int witness_lock_order_add(struct witness *parent, 350 struct witness *child); 351 static int witness_lock_order_check(struct witness *parent, 352 struct witness *child); 353 static struct witness_lock_order_data *witness_lock_order_get( 354 struct witness *parent, 355 struct witness *child); 356 static void witness_list_lock(struct lock_instance *instance, 357 int (*prnt)(const char *fmt, ...)); 358 static int witness_output(const char *fmt, ...) __printflike(1, 2); 359 static int witness_output_drain(void *arg __unused, const char *data, 360 int len); 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 FEATURE(witness, "kernel has witness(9) support"); 365 366 static SYSCTL_NODE(_debug, OID_AUTO, witness, CTLFLAG_RW | CTLFLAG_MPSAFE, NULL, 367 "Witness Locking"); 368 369 /* 370 * If set to 0, lock order checking is disabled. If set to -1, 371 * witness is completely disabled. Otherwise witness performs full 372 * lock order checking for all locks. At runtime, lock order checking 373 * may be toggled. However, witness cannot be reenabled once it is 374 * completely disabled. 375 */ 376 static int witness_watch = 1; 377 SYSCTL_PROC(_debug_witness, OID_AUTO, watch, 378 CTLFLAG_RWTUN | CTLTYPE_INT | CTLFLAG_MPSAFE, NULL, 0, 379 sysctl_debug_witness_watch, "I", 380 "witness is watching lock operations"); 381 382 #ifdef KDB 383 /* 384 * When KDB is enabled and witness_kdb is 1, it will cause the system 385 * to drop into kdebug() when: 386 * - a lock hierarchy violation occurs 387 * - locks are held when going to sleep. 388 */ 389 #ifdef WITNESS_KDB 390 int witness_kdb = 1; 391 #else 392 int witness_kdb = 0; 393 #endif 394 SYSCTL_INT(_debug_witness, OID_AUTO, kdb, CTLFLAG_RWTUN, &witness_kdb, 0, ""); 395 #endif /* KDB */ 396 397 #if defined(DDB) || defined(KDB) 398 /* 399 * When DDB or KDB is enabled and witness_trace is 1, it will cause the system 400 * to print a stack trace: 401 * - a lock hierarchy violation occurs 402 * - locks are held when going to sleep. 403 */ 404 int witness_trace = 1; 405 SYSCTL_INT(_debug_witness, OID_AUTO, trace, CTLFLAG_RWTUN, &witness_trace, 0, ""); 406 #endif /* DDB || KDB */ 407 408 #ifdef WITNESS_SKIPSPIN 409 int witness_skipspin = 1; 410 #else 411 int witness_skipspin = 0; 412 #endif 413 SYSCTL_INT(_debug_witness, OID_AUTO, skipspin, CTLFLAG_RDTUN, &witness_skipspin, 0, ""); 414 415 int badstack_sbuf_size; 416 417 int witness_count = WITNESS_COUNT; 418 SYSCTL_INT(_debug_witness, OID_AUTO, witness_count, CTLFLAG_RDTUN, 419 &witness_count, 0, ""); 420 421 /* 422 * Output channel for witness messages. By default we print to the console. 423 */ 424 enum witness_channel { 425 WITNESS_CONSOLE, 426 WITNESS_LOG, 427 WITNESS_NONE, 428 }; 429 430 static enum witness_channel witness_channel = WITNESS_CONSOLE; 431 SYSCTL_PROC(_debug_witness, OID_AUTO, output_channel, 432 CTLTYPE_STRING | CTLFLAG_RWTUN | CTLFLAG_MPSAFE, NULL, 0, 433 sysctl_debug_witness_channel, "A", 434 "Output channel for warnings"); 435 436 /* 437 * Call this to print out the relations between locks. 438 */ 439 SYSCTL_PROC(_debug_witness, OID_AUTO, fullgraph, 440 CTLTYPE_STRING | CTLFLAG_RD | CTLFLAG_MPSAFE, NULL, 0, 441 sysctl_debug_witness_fullgraph, "A", 442 "Show locks relation graphs"); 443 444 /* 445 * Call this to print out the witness faulty stacks. 446 */ 447 SYSCTL_PROC(_debug_witness, OID_AUTO, badstacks, 448 CTLTYPE_STRING | CTLFLAG_RD | CTLFLAG_MPSAFE, NULL, 0, 449 sysctl_debug_witness_badstacks, "A", 450 "Show bad witness stacks"); 451 452 static struct mtx w_mtx; 453 454 /* w_list */ 455 static struct witness_list w_free = STAILQ_HEAD_INITIALIZER(w_free); 456 static struct witness_list w_all = STAILQ_HEAD_INITIALIZER(w_all); 457 458 /* w_typelist */ 459 static struct witness_list w_spin = STAILQ_HEAD_INITIALIZER(w_spin); 460 static struct witness_list w_sleep = STAILQ_HEAD_INITIALIZER(w_sleep); 461 462 /* lock list */ 463 static struct lock_list_entry *w_lock_list_free = NULL; 464 static struct witness_pendhelp pending_locks[WITNESS_PENDLIST]; 465 static u_int pending_cnt; 466 467 static int w_free_cnt, w_spin_cnt, w_sleep_cnt; 468 SYSCTL_INT(_debug_witness, OID_AUTO, free_cnt, CTLFLAG_RD, &w_free_cnt, 0, ""); 469 SYSCTL_INT(_debug_witness, OID_AUTO, spin_cnt, CTLFLAG_RD, &w_spin_cnt, 0, ""); 470 SYSCTL_INT(_debug_witness, OID_AUTO, sleep_cnt, CTLFLAG_RD, &w_sleep_cnt, 0, 471 ""); 472 473 static struct witness *w_data; 474 static uint8_t **w_rmatrix; 475 static struct lock_list_entry w_locklistdata[LOCK_CHILDCOUNT]; 476 static struct witness_hash w_hash; /* The witness hash table. */ 477 478 /* The lock order data hash */ 479 static struct witness_lock_order_data w_lodata[WITNESS_LO_DATA_COUNT]; 480 static struct witness_lock_order_data *w_lofree = NULL; 481 static struct witness_lock_order_hash w_lohash; 482 static int w_max_used_index = 0; 483 static unsigned int w_generation = 0; 484 static const char w_notrunning[] = "Witness not running\n"; 485 static const char w_stillcold[] = "Witness is still cold\n"; 486 #ifdef __i386__ 487 static const char w_notallowed[] = "The sysctl is disabled on the arch\n"; 488 #endif 489 490 static struct witness_order_list_entry order_lists[] = { 491 /* 492 * sx locks 493 */ 494 { "proctree", &lock_class_sx }, 495 { "allproc", &lock_class_sx }, 496 { "allprison", &lock_class_sx }, 497 { NULL, NULL }, 498 /* 499 * Various mutexes 500 */ 501 { "Giant", &lock_class_mtx_sleep }, 502 { "pipe mutex", &lock_class_mtx_sleep }, 503 { "sigio lock", &lock_class_mtx_sleep }, 504 { "process group", &lock_class_mtx_sleep }, 505 #ifdef HWPMC_HOOKS 506 { "pmc-sleep", &lock_class_mtx_sleep }, 507 #endif 508 { "process lock", &lock_class_mtx_sleep }, 509 { "session", &lock_class_mtx_sleep }, 510 { "uidinfo hash", &lock_class_rw }, 511 { "time lock", &lock_class_mtx_sleep }, 512 { NULL, NULL }, 513 /* 514 * umtx 515 */ 516 { "umtx lock", &lock_class_mtx_sleep }, 517 { NULL, NULL }, 518 /* 519 * Sockets 520 */ 521 { "accept", &lock_class_mtx_sleep }, 522 { "so_snd", &lock_class_mtx_sleep }, 523 { "so_rcv", &lock_class_mtx_sleep }, 524 { "sellck", &lock_class_mtx_sleep }, 525 { NULL, NULL }, 526 /* 527 * Routing 528 */ 529 { "so_rcv", &lock_class_mtx_sleep }, 530 { "radix node head", &lock_class_rm }, 531 { "ifaddr", &lock_class_mtx_sleep }, 532 { NULL, NULL }, 533 /* 534 * IPv4 multicast: 535 * protocol locks before interface locks, after UDP locks. 536 */ 537 { "in_multi_sx", &lock_class_sx }, 538 { "udpinp", &lock_class_rw }, 539 { "in_multi_list_mtx", &lock_class_mtx_sleep }, 540 { "igmp_mtx", &lock_class_mtx_sleep }, 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 { "if_addr_lock", &lock_class_mtx_sleep }, 552 { NULL, NULL }, 553 /* 554 * UNIX Domain Sockets 555 */ 556 { "unp_link_rwlock", &lock_class_rw }, 557 { "unp_list_lock", &lock_class_mtx_sleep }, 558 { "unp", &lock_class_mtx_sleep }, 559 { "so_snd", &lock_class_mtx_sleep }, 560 { NULL, NULL }, 561 /* 562 * UDP/IP 563 */ 564 { "udpinp", &lock_class_rw }, 565 { "udp", &lock_class_mtx_sleep }, 566 { "so_snd", &lock_class_mtx_sleep }, 567 { NULL, NULL }, 568 /* 569 * TCP/IP 570 */ 571 { "tcpinp", &lock_class_rw }, 572 { "tcp", &lock_class_mtx_sleep }, 573 { "so_snd", &lock_class_mtx_sleep }, 574 { NULL, NULL }, 575 /* 576 * BPF 577 */ 578 { "bpf global lock", &lock_class_sx }, 579 { "bpf cdev lock", &lock_class_mtx_sleep }, 580 { NULL, NULL }, 581 /* 582 * NFS server 583 */ 584 { "nfsd_mtx", &lock_class_mtx_sleep }, 585 { "so_snd", &lock_class_mtx_sleep }, 586 { NULL, NULL }, 587 588 /* 589 * IEEE 802.11 590 */ 591 { "802.11 com lock", &lock_class_mtx_sleep}, 592 { NULL, NULL }, 593 /* 594 * Network drivers 595 */ 596 { "network driver", &lock_class_mtx_sleep}, 597 { NULL, NULL }, 598 599 /* 600 * Netgraph 601 */ 602 { "ng_node", &lock_class_mtx_sleep }, 603 { "ng_worklist", &lock_class_mtx_sleep }, 604 { NULL, NULL }, 605 /* 606 * CDEV 607 */ 608 { "vm map (system)", &lock_class_mtx_sleep }, 609 { "vnode interlock", &lock_class_mtx_sleep }, 610 { "cdev", &lock_class_mtx_sleep }, 611 { "devthrd", &lock_class_mtx_sleep }, 612 { NULL, NULL }, 613 /* 614 * VM 615 */ 616 { "vm map (user)", &lock_class_sx }, 617 { "vm object", &lock_class_rw }, 618 { "vm page", &lock_class_mtx_sleep }, 619 { "pmap pv global", &lock_class_rw }, 620 { "pmap", &lock_class_mtx_sleep }, 621 { "pmap pv list", &lock_class_rw }, 622 { "vm page free queue", &lock_class_mtx_sleep }, 623 { "vm pagequeue", &lock_class_mtx_sleep }, 624 { NULL, NULL }, 625 /* 626 * kqueue/VFS interaction 627 */ 628 { "kqueue", &lock_class_mtx_sleep }, 629 { "struct mount mtx", &lock_class_mtx_sleep }, 630 { "vnode interlock", &lock_class_mtx_sleep }, 631 { NULL, NULL }, 632 /* 633 * VFS namecache 634 */ 635 { "ncvn", &lock_class_mtx_sleep }, 636 { "ncbuc", &lock_class_mtx_sleep }, 637 { "vnode interlock", &lock_class_mtx_sleep }, 638 { "ncneg", &lock_class_mtx_sleep }, 639 { NULL, NULL }, 640 /* 641 * ZFS locking 642 */ 643 { "dn->dn_mtx", &lock_class_sx }, 644 { "dr->dt.di.dr_mtx", &lock_class_sx }, 645 { "db->db_mtx", &lock_class_sx }, 646 { NULL, NULL }, 647 /* 648 * TCP log locks 649 */ 650 { "TCP ID tree", &lock_class_rw }, 651 { "tcp log id bucket", &lock_class_mtx_sleep }, 652 { "tcpinp", &lock_class_rw }, 653 { "TCP log expireq", &lock_class_mtx_sleep }, 654 { NULL, NULL }, 655 /* 656 * spin locks 657 */ 658 #ifdef SMP 659 { "ap boot", &lock_class_mtx_spin }, 660 #endif 661 { "rm.mutex_mtx", &lock_class_mtx_spin }, 662 #ifdef __i386__ 663 { "cy", &lock_class_mtx_spin }, 664 #endif 665 { "scc_hwmtx", &lock_class_mtx_spin }, 666 { "uart_hwmtx", &lock_class_mtx_spin }, 667 { "fast_taskqueue", &lock_class_mtx_spin }, 668 { "intr table", &lock_class_mtx_spin }, 669 { "process slock", &lock_class_mtx_spin }, 670 { "syscons video lock", &lock_class_mtx_spin }, 671 { "sleepq chain", &lock_class_mtx_spin }, 672 { "rm_spinlock", &lock_class_mtx_spin }, 673 { "turnstile chain", &lock_class_mtx_spin }, 674 { "turnstile lock", &lock_class_mtx_spin }, 675 { "sched lock", &lock_class_mtx_spin }, 676 { "td_contested", &lock_class_mtx_spin }, 677 { "callout", &lock_class_mtx_spin }, 678 { "entropy harvest mutex", &lock_class_mtx_spin }, 679 #ifdef SMP 680 { "smp rendezvous", &lock_class_mtx_spin }, 681 #endif 682 #ifdef __powerpc__ 683 { "tlb0", &lock_class_mtx_spin }, 684 #endif 685 { NULL, NULL }, 686 { "sched lock", &lock_class_mtx_spin }, 687 #ifdef HWPMC_HOOKS 688 { "pmc-per-proc", &lock_class_mtx_spin }, 689 #endif 690 { NULL, NULL }, 691 /* 692 * leaf locks 693 */ 694 { "intrcnt", &lock_class_mtx_spin }, 695 { "icu", &lock_class_mtx_spin }, 696 #ifdef __i386__ 697 { "allpmaps", &lock_class_mtx_spin }, 698 { "descriptor tables", &lock_class_mtx_spin }, 699 #endif 700 { "clk", &lock_class_mtx_spin }, 701 { "cpuset", &lock_class_mtx_spin }, 702 { "mprof lock", &lock_class_mtx_spin }, 703 { "zombie lock", &lock_class_mtx_spin }, 704 { "ALD Queue", &lock_class_mtx_spin }, 705 #if defined(__i386__) || defined(__amd64__) 706 { "pcicfg", &lock_class_mtx_spin }, 707 { "NDIS thread lock", &lock_class_mtx_spin }, 708 #endif 709 { "tw_osl_io_lock", &lock_class_mtx_spin }, 710 { "tw_osl_q_lock", &lock_class_mtx_spin }, 711 { "tw_cl_io_lock", &lock_class_mtx_spin }, 712 { "tw_cl_intr_lock", &lock_class_mtx_spin }, 713 { "tw_cl_gen_lock", &lock_class_mtx_spin }, 714 #ifdef HWPMC_HOOKS 715 { "pmc-leaf", &lock_class_mtx_spin }, 716 #endif 717 { "blocked lock", &lock_class_mtx_spin }, 718 { NULL, NULL }, 719 { NULL, NULL } 720 }; 721 722 /* 723 * Pairs of locks which have been blessed. Witness does not complain about 724 * order problems with blessed lock pairs. Please do not add an entry to the 725 * table without an explanatory comment. 726 */ 727 static struct witness_blessed blessed_list[] = { 728 /* 729 * See the comment in ufs_dirhash.c. Basically, a vnode lock serializes 730 * both lock orders, so a deadlock cannot happen as a result of this 731 * LOR. 732 */ 733 { "dirhash", "bufwait" }, 734 735 /* 736 * A UFS vnode may be locked in vget() while a buffer belonging to the 737 * parent directory vnode is locked. 738 */ 739 { "ufs", "bufwait" }, 740 741 /* 742 * The tarfs decompression stream vnode may be locked while a 743 * buffer belonging to a tarfs data vnode is locked. 744 */ 745 { "tarfs", "bufwait" }, 746 }; 747 748 /* 749 * This global is set to 0 once it becomes safe to use the witness code. 750 */ 751 static int witness_cold = 1; 752 753 /* 754 * This global is set to 1 once the static lock orders have been enrolled 755 * so that a warning can be issued for any spin locks enrolled later. 756 */ 757 static int witness_spin_warn = 0; 758 759 /* Trim useless garbage from filenames. */ 760 static const char * 761 fixup_filename(const char *file) 762 { 763 764 if (file == NULL) 765 return (NULL); 766 while (strncmp(file, "../", 3) == 0) 767 file += 3; 768 return (file); 769 } 770 771 /* 772 * Calculate the size of early witness structures. 773 */ 774 int 775 witness_startup_count(void) 776 { 777 int sz; 778 779 sz = sizeof(struct witness) * witness_count; 780 sz += sizeof(*w_rmatrix) * (witness_count + 1); 781 sz += sizeof(*w_rmatrix[0]) * (witness_count + 1) * 782 (witness_count + 1); 783 784 return (sz); 785 } 786 787 /* 788 * The WITNESS-enabled diagnostic code. Note that the witness code does 789 * assume that the early boot is single-threaded at least until after this 790 * routine is completed. 791 */ 792 void 793 witness_startup(void *mem) 794 { 795 struct lock_object *lock; 796 struct witness_order_list_entry *order; 797 struct witness *w, *w1; 798 uintptr_t p; 799 int i; 800 801 p = (uintptr_t)mem; 802 w_data = (void *)p; 803 p += sizeof(struct witness) * witness_count; 804 805 w_rmatrix = (void *)p; 806 p += sizeof(*w_rmatrix) * (witness_count + 1); 807 808 for (i = 0; i < witness_count + 1; i++) { 809 w_rmatrix[i] = (void *)p; 810 p += sizeof(*w_rmatrix[i]) * (witness_count + 1); 811 } 812 badstack_sbuf_size = witness_count * 256; 813 814 /* 815 * We have to release Giant before initializing its witness 816 * structure so that WITNESS doesn't get confused. 817 */ 818 mtx_unlock(&Giant); 819 mtx_assert(&Giant, MA_NOTOWNED); 820 821 CTR1(KTR_WITNESS, "%s: initializing witness", __func__); 822 mtx_init(&w_mtx, "witness lock", NULL, MTX_SPIN | MTX_QUIET | 823 MTX_NOWITNESS | MTX_NOPROFILE); 824 for (i = witness_count - 1; i >= 0; i--) { 825 w = &w_data[i]; 826 memset(w, 0, sizeof(*w)); 827 w_data[i].w_index = i; /* Witness index never changes. */ 828 witness_free(w); 829 } 830 KASSERT(STAILQ_FIRST(&w_free)->w_index == 0, 831 ("%s: Invalid list of free witness objects", __func__)); 832 833 /* Witness with index 0 is not used to aid in debugging. */ 834 STAILQ_REMOVE_HEAD(&w_free, w_list); 835 w_free_cnt--; 836 837 for (i = 0; i < witness_count; i++) { 838 memset(w_rmatrix[i], 0, sizeof(*w_rmatrix[i]) * 839 (witness_count + 1)); 840 } 841 842 for (i = 0; i < LOCK_CHILDCOUNT; i++) 843 witness_lock_list_free(&w_locklistdata[i]); 844 witness_init_hash_tables(); 845 846 /* First add in all the specified order lists. */ 847 for (order = order_lists; order->w_name != NULL; order++) { 848 w = enroll(order->w_name, order->w_class); 849 if (w == NULL) 850 continue; 851 w->w_file = "order list"; 852 for (order++; order->w_name != NULL; order++) { 853 w1 = enroll(order->w_name, order->w_class); 854 if (w1 == NULL) 855 continue; 856 w1->w_file = "order list"; 857 itismychild(w, w1); 858 w = w1; 859 } 860 } 861 witness_spin_warn = 1; 862 863 /* Iterate through all locks and add them to witness. */ 864 for (i = 0; pending_locks[i].wh_lock != NULL; i++) { 865 lock = pending_locks[i].wh_lock; 866 KASSERT(lock->lo_flags & LO_WITNESS, 867 ("%s: lock %s is on pending list but not LO_WITNESS", 868 __func__, lock->lo_name)); 869 lock->lo_witness = enroll(pending_locks[i].wh_type, 870 LOCK_CLASS(lock)); 871 } 872 873 /* Mark the witness code as being ready for use. */ 874 witness_cold = 0; 875 876 mtx_lock(&Giant); 877 } 878 879 void 880 witness_init(struct lock_object *lock, const char *type) 881 { 882 struct lock_class *class; 883 884 /* Various sanity checks. */ 885 class = LOCK_CLASS(lock); 886 if ((lock->lo_flags & LO_RECURSABLE) != 0 && 887 (class->lc_flags & LC_RECURSABLE) == 0) 888 kassert_panic("%s: lock (%s) %s can not be recursable", 889 __func__, class->lc_name, lock->lo_name); 890 if ((lock->lo_flags & LO_SLEEPABLE) != 0 && 891 (class->lc_flags & LC_SLEEPABLE) == 0) 892 kassert_panic("%s: lock (%s) %s can not be sleepable", 893 __func__, class->lc_name, lock->lo_name); 894 if ((lock->lo_flags & LO_UPGRADABLE) != 0 && 895 (class->lc_flags & LC_UPGRADABLE) == 0) 896 kassert_panic("%s: lock (%s) %s can not be upgradable", 897 __func__, class->lc_name, lock->lo_name); 898 899 /* 900 * If we shouldn't watch this lock, then just clear lo_witness. 901 * Otherwise, if witness_cold is set, then it is too early to 902 * enroll this lock, so defer it to witness_initialize() by adding 903 * it to the pending_locks list. If it is not too early, then enroll 904 * the lock now. 905 */ 906 if (witness_watch < 1 || KERNEL_PANICKED() || 907 (lock->lo_flags & LO_WITNESS) == 0) 908 lock->lo_witness = NULL; 909 else if (witness_cold) { 910 pending_locks[pending_cnt].wh_lock = lock; 911 pending_locks[pending_cnt++].wh_type = type; 912 if (pending_cnt > WITNESS_PENDLIST) 913 panic("%s: pending locks list is too small, " 914 "increase WITNESS_PENDLIST\n", 915 __func__); 916 } else 917 lock->lo_witness = enroll(type, class); 918 } 919 920 void 921 witness_destroy(struct lock_object *lock) 922 { 923 struct lock_class *class; 924 struct witness *w; 925 926 class = LOCK_CLASS(lock); 927 928 if (witness_cold) 929 panic("lock (%s) %s destroyed while witness_cold", 930 class->lc_name, lock->lo_name); 931 932 /* XXX: need to verify that no one holds the lock */ 933 if ((lock->lo_flags & LO_WITNESS) == 0 || lock->lo_witness == NULL) 934 return; 935 w = lock->lo_witness; 936 937 mtx_lock_spin(&w_mtx); 938 MPASS(w->w_refcount > 0); 939 w->w_refcount--; 940 941 if (w->w_refcount == 0) 942 depart(w); 943 mtx_unlock_spin(&w_mtx); 944 } 945 946 #ifdef DDB 947 static void 948 witness_ddb_compute_levels(void) 949 { 950 struct witness *w; 951 952 /* 953 * First clear all levels. 954 */ 955 STAILQ_FOREACH(w, &w_all, w_list) 956 w->w_ddb_level = -1; 957 958 /* 959 * Look for locks with no parents and level all their descendants. 960 */ 961 STAILQ_FOREACH(w, &w_all, w_list) { 962 /* If the witness has ancestors (is not a root), skip it. */ 963 if (w->w_num_ancestors > 0) 964 continue; 965 witness_ddb_level_descendants(w, 0); 966 } 967 } 968 969 static void 970 witness_ddb_level_descendants(struct witness *w, int l) 971 { 972 int i; 973 974 if (w->w_ddb_level >= l) 975 return; 976 977 w->w_ddb_level = l; 978 l++; 979 980 for (i = 1; i <= w_max_used_index; i++) { 981 if (w_rmatrix[w->w_index][i] & WITNESS_PARENT) 982 witness_ddb_level_descendants(&w_data[i], l); 983 } 984 } 985 986 static void 987 witness_ddb_display_descendants(int(*prnt)(const char *fmt, ...), 988 struct witness *w, int indent) 989 { 990 int i; 991 992 for (i = 0; i < indent; i++) 993 prnt(" "); 994 prnt("%s (type: %s, depth: %d, active refs: %d)", 995 w->w_name, w->w_class->lc_name, 996 w->w_ddb_level, w->w_refcount); 997 if (w->w_displayed) { 998 prnt(" -- (already displayed)\n"); 999 return; 1000 } 1001 w->w_displayed = 1; 1002 if (w->w_file != NULL && w->w_line != 0) 1003 prnt(" -- last acquired @ %s:%d\n", fixup_filename(w->w_file), 1004 w->w_line); 1005 else 1006 prnt(" -- never acquired\n"); 1007 indent++; 1008 WITNESS_INDEX_ASSERT(w->w_index); 1009 for (i = 1; i <= w_max_used_index; i++) { 1010 if (db_pager_quit) 1011 return; 1012 if (w_rmatrix[w->w_index][i] & WITNESS_PARENT) 1013 witness_ddb_display_descendants(prnt, &w_data[i], 1014 indent); 1015 } 1016 } 1017 1018 static void 1019 witness_ddb_display_list(int(*prnt)(const char *fmt, ...), 1020 struct witness_list *list) 1021 { 1022 struct witness *w; 1023 1024 STAILQ_FOREACH(w, list, w_typelist) { 1025 if (w->w_file == NULL || w->w_ddb_level > 0) 1026 continue; 1027 1028 /* This lock has no anscestors - display its descendants. */ 1029 witness_ddb_display_descendants(prnt, w, 0); 1030 if (db_pager_quit) 1031 return; 1032 } 1033 } 1034 1035 static void 1036 witness_ddb_display(int(*prnt)(const char *fmt, ...)) 1037 { 1038 struct witness *w; 1039 1040 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); 1041 witness_ddb_compute_levels(); 1042 1043 /* Clear all the displayed flags. */ 1044 STAILQ_FOREACH(w, &w_all, w_list) 1045 w->w_displayed = 0; 1046 1047 /* 1048 * First, handle sleep locks which have been acquired at least 1049 * once. 1050 */ 1051 prnt("Sleep locks:\n"); 1052 witness_ddb_display_list(prnt, &w_sleep); 1053 if (db_pager_quit) 1054 return; 1055 1056 /* 1057 * Now do spin locks which have been acquired at least once. 1058 */ 1059 prnt("\nSpin locks:\n"); 1060 witness_ddb_display_list(prnt, &w_spin); 1061 if (db_pager_quit) 1062 return; 1063 1064 /* 1065 * Finally, any locks which have not been acquired yet. 1066 */ 1067 prnt("\nLocks which were never acquired:\n"); 1068 STAILQ_FOREACH(w, &w_all, w_list) { 1069 if (w->w_file != NULL || w->w_refcount == 0) 1070 continue; 1071 prnt("%s (type: %s, depth: %d)\n", w->w_name, 1072 w->w_class->lc_name, w->w_ddb_level); 1073 if (db_pager_quit) 1074 return; 1075 } 1076 } 1077 #endif /* DDB */ 1078 1079 int 1080 witness_defineorder(struct lock_object *lock1, struct lock_object *lock2) 1081 { 1082 1083 if (witness_watch == -1 || KERNEL_PANICKED()) 1084 return (0); 1085 1086 /* Require locks that witness knows about. */ 1087 if (lock1 == NULL || lock1->lo_witness == NULL || lock2 == NULL || 1088 lock2->lo_witness == NULL) 1089 return (EINVAL); 1090 1091 mtx_assert(&w_mtx, MA_NOTOWNED); 1092 mtx_lock_spin(&w_mtx); 1093 1094 /* 1095 * If we already have either an explicit or implied lock order that 1096 * is the other way around, then return an error. 1097 */ 1098 if (witness_watch && 1099 isitmydescendant(lock2->lo_witness, lock1->lo_witness)) { 1100 mtx_unlock_spin(&w_mtx); 1101 return (EDOOFUS); 1102 } 1103 1104 /* Try to add the new order. */ 1105 CTR3(KTR_WITNESS, "%s: adding %s as a child of %s", __func__, 1106 lock2->lo_witness->w_name, lock1->lo_witness->w_name); 1107 itismychild(lock1->lo_witness, lock2->lo_witness); 1108 mtx_unlock_spin(&w_mtx); 1109 return (0); 1110 } 1111 1112 void 1113 witness_checkorder(struct lock_object *lock, int flags, const char *file, 1114 int line, struct lock_object *interlock) 1115 { 1116 struct lock_list_entry *lock_list, *lle; 1117 struct lock_instance *lock1, *lock2, *plock; 1118 struct lock_class *class, *iclass; 1119 struct witness *w, *w1; 1120 struct thread *td; 1121 int i, j; 1122 1123 if (witness_cold || witness_watch < 1 || lock->lo_witness == NULL || 1124 KERNEL_PANICKED()) 1125 return; 1126 1127 w = lock->lo_witness; 1128 class = LOCK_CLASS(lock); 1129 td = curthread; 1130 1131 if (class->lc_flags & LC_SLEEPLOCK) { 1132 /* 1133 * Since spin locks include a critical section, this check 1134 * implicitly enforces a lock order of all sleep locks before 1135 * all spin locks. 1136 */ 1137 if (td->td_critnest != 0 && !kdb_active) 1138 kassert_panic("acquiring blockable sleep lock with " 1139 "spinlock or critical section held (%s) %s @ %s:%d", 1140 class->lc_name, lock->lo_name, 1141 fixup_filename(file), line); 1142 1143 /* 1144 * If this is the first lock acquired then just return as 1145 * no order checking is needed. 1146 */ 1147 lock_list = td->td_sleeplocks; 1148 if (lock_list == NULL || lock_list->ll_count == 0) 1149 return; 1150 } else { 1151 /* 1152 * If this is the first lock, just return as no order 1153 * checking is needed. Avoid problems with thread 1154 * migration pinning the thread while checking if 1155 * spinlocks are held. If at least one spinlock is held 1156 * the thread is in a safe path and it is allowed to 1157 * unpin it. 1158 */ 1159 sched_pin(); 1160 lock_list = PCPU_GET(spinlocks); 1161 if (lock_list == NULL || lock_list->ll_count == 0) { 1162 sched_unpin(); 1163 return; 1164 } 1165 sched_unpin(); 1166 } 1167 1168 /* 1169 * Check to see if we are recursing on a lock we already own. If 1170 * so, make sure that we don't mismatch exclusive and shared lock 1171 * acquires. 1172 */ 1173 lock1 = find_instance(lock_list, lock); 1174 if (lock1 != NULL) { 1175 if ((lock1->li_flags & LI_EXCLUSIVE) != 0 && 1176 (flags & LOP_EXCLUSIVE) == 0) { 1177 witness_output("shared lock of (%s) %s @ %s:%d\n", 1178 class->lc_name, lock->lo_name, 1179 fixup_filename(file), line); 1180 witness_output("while exclusively locked from %s:%d\n", 1181 fixup_filename(lock1->li_file), lock1->li_line); 1182 kassert_panic("excl->share"); 1183 } 1184 if ((lock1->li_flags & LI_EXCLUSIVE) == 0 && 1185 (flags & LOP_EXCLUSIVE) != 0) { 1186 witness_output("exclusive lock of (%s) %s @ %s:%d\n", 1187 class->lc_name, lock->lo_name, 1188 fixup_filename(file), line); 1189 witness_output("while share locked from %s:%d\n", 1190 fixup_filename(lock1->li_file), lock1->li_line); 1191 kassert_panic("share->excl"); 1192 } 1193 return; 1194 } 1195 1196 /* Warn if the interlock is not locked exactly once. */ 1197 if (interlock != NULL) { 1198 iclass = LOCK_CLASS(interlock); 1199 lock1 = find_instance(lock_list, interlock); 1200 if (lock1 == NULL) 1201 kassert_panic("interlock (%s) %s not locked @ %s:%d", 1202 iclass->lc_name, interlock->lo_name, 1203 fixup_filename(file), line); 1204 else if ((lock1->li_flags & LI_RECURSEMASK) != 0) 1205 kassert_panic("interlock (%s) %s recursed @ %s:%d", 1206 iclass->lc_name, interlock->lo_name, 1207 fixup_filename(file), line); 1208 } 1209 1210 /* 1211 * Find the previously acquired lock, but ignore interlocks. 1212 */ 1213 plock = &lock_list->ll_children[lock_list->ll_count - 1]; 1214 if (interlock != NULL && plock->li_lock == interlock) { 1215 if (lock_list->ll_count > 1) 1216 plock = 1217 &lock_list->ll_children[lock_list->ll_count - 2]; 1218 else { 1219 lle = lock_list->ll_next; 1220 1221 /* 1222 * The interlock is the only lock we hold, so 1223 * simply return. 1224 */ 1225 if (lle == NULL) 1226 return; 1227 plock = &lle->ll_children[lle->ll_count - 1]; 1228 } 1229 } 1230 1231 /* 1232 * Try to perform most checks without a lock. If this succeeds we 1233 * can skip acquiring the lock and return success. Otherwise we redo 1234 * the check with the lock held to handle races with concurrent updates. 1235 */ 1236 w1 = plock->li_lock->lo_witness; 1237 if (witness_lock_order_check(w1, w)) 1238 return; 1239 1240 mtx_lock_spin(&w_mtx); 1241 if (witness_lock_order_check(w1, w)) { 1242 mtx_unlock_spin(&w_mtx); 1243 return; 1244 } 1245 witness_lock_order_add(w1, w); 1246 1247 /* 1248 * Check for duplicate locks of the same type. Note that we only 1249 * have to check for this on the last lock we just acquired. Any 1250 * other cases will be caught as lock order violations. 1251 */ 1252 if (w1 == w) { 1253 i = w->w_index; 1254 if (!(lock->lo_flags & LO_DUPOK) && !(flags & LOP_DUPOK) && 1255 !(w_rmatrix[i][i] & WITNESS_REVERSAL)) { 1256 w_rmatrix[i][i] |= WITNESS_REVERSAL; 1257 w->w_reversed = 1; 1258 mtx_unlock_spin(&w_mtx); 1259 witness_output( 1260 "acquiring duplicate lock of same type: \"%s\"\n", 1261 w->w_name); 1262 witness_output(" 1st %s @ %s:%d\n", plock->li_lock->lo_name, 1263 fixup_filename(plock->li_file), plock->li_line); 1264 witness_output(" 2nd %s @ %s:%d\n", lock->lo_name, 1265 fixup_filename(file), line); 1266 witness_debugger(1, __func__); 1267 } else 1268 mtx_unlock_spin(&w_mtx); 1269 return; 1270 } 1271 mtx_assert(&w_mtx, MA_OWNED); 1272 1273 /* 1274 * If we know that the lock we are acquiring comes after 1275 * the lock we most recently acquired in the lock order tree, 1276 * then there is no need for any further checks. 1277 */ 1278 if (isitmychild(w1, w)) 1279 goto out; 1280 1281 for (j = 0, lle = lock_list; lle != NULL; lle = lle->ll_next) { 1282 for (i = lle->ll_count - 1; i >= 0; i--, j++) { 1283 struct stack pstack; 1284 bool pstackv, trace; 1285 1286 MPASS(j < LOCK_CHILDCOUNT * LOCK_NCHILDREN); 1287 lock1 = &lle->ll_children[i]; 1288 1289 /* 1290 * Ignore the interlock. 1291 */ 1292 if (interlock == lock1->li_lock) 1293 continue; 1294 1295 /* 1296 * If this lock doesn't undergo witness checking, 1297 * then skip it. 1298 */ 1299 w1 = lock1->li_lock->lo_witness; 1300 if (w1 == NULL) { 1301 KASSERT((lock1->li_lock->lo_flags & LO_WITNESS) == 0, 1302 ("lock missing witness structure")); 1303 continue; 1304 } 1305 1306 /* 1307 * If we are locking Giant and this is a sleepable 1308 * lock, then skip it. 1309 */ 1310 if ((lock1->li_flags & LI_SLEEPABLE) != 0 && 1311 lock == &Giant.lock_object) 1312 continue; 1313 1314 /* 1315 * If we are locking a sleepable lock and this lock 1316 * is Giant, then skip it. 1317 */ 1318 if ((lock->lo_flags & LO_SLEEPABLE) != 0 && 1319 (flags & LOP_NOSLEEP) == 0 && 1320 lock1->li_lock == &Giant.lock_object) 1321 continue; 1322 1323 /* 1324 * If we are locking a sleepable lock and this lock 1325 * isn't sleepable, we want to treat it as a lock 1326 * order violation to enfore a general lock order of 1327 * sleepable locks before non-sleepable locks. 1328 */ 1329 if ((lock->lo_flags & LO_SLEEPABLE) != 0 && 1330 (flags & LOP_NOSLEEP) == 0 && 1331 (lock1->li_flags & LI_SLEEPABLE) == 0) 1332 goto reversal; 1333 1334 /* 1335 * If we are locking Giant and this is a non-sleepable 1336 * lock, then treat it as a reversal. 1337 */ 1338 if ((lock1->li_flags & LI_SLEEPABLE) == 0 && 1339 lock == &Giant.lock_object) 1340 goto reversal; 1341 1342 /* 1343 * Check the lock order hierarchy for a reveresal. 1344 */ 1345 if (!isitmydescendant(w, w1)) 1346 continue; 1347 reversal: 1348 1349 /* 1350 * We have a lock order violation, check to see if it 1351 * is allowed or has already been yelled about. 1352 */ 1353 1354 /* Bail if this violation is known */ 1355 if (w_rmatrix[w1->w_index][w->w_index] & WITNESS_REVERSAL) 1356 goto out; 1357 1358 /* Record this as a violation */ 1359 w_rmatrix[w1->w_index][w->w_index] |= WITNESS_REVERSAL; 1360 w_rmatrix[w->w_index][w1->w_index] |= WITNESS_REVERSAL; 1361 w->w_reversed = w1->w_reversed = 1; 1362 witness_increment_graph_generation(); 1363 1364 /* 1365 * If the lock order is blessed, bail before logging 1366 * anything. We don't look for other lock order 1367 * violations though, which may be a bug. 1368 */ 1369 if (blessed(w, w1)) 1370 goto out; 1371 1372 trace = atomic_load_int(&witness_trace); 1373 if (trace) { 1374 struct witness_lock_order_data *data; 1375 1376 pstackv = false; 1377 data = witness_lock_order_get(w, w1); 1378 if (data != NULL) { 1379 stack_copy(&data->wlod_stack, 1380 &pstack); 1381 pstackv = true; 1382 } 1383 } 1384 mtx_unlock_spin(&w_mtx); 1385 1386 #ifdef WITNESS_NO_VNODE 1387 /* 1388 * There are known LORs between VNODE locks. They are 1389 * not an indication of a bug. VNODE locks are flagged 1390 * as such (LO_IS_VNODE) and we don't yell if the LOR 1391 * is between 2 VNODE locks. 1392 */ 1393 if ((lock->lo_flags & LO_IS_VNODE) != 0 && 1394 (lock1->li_lock->lo_flags & LO_IS_VNODE) != 0) 1395 return; 1396 #endif 1397 1398 /* 1399 * Ok, yell about it. 1400 */ 1401 if ((lock->lo_flags & LO_SLEEPABLE) != 0 && 1402 (flags & LOP_NOSLEEP) == 0 && 1403 (lock1->li_flags & LI_SLEEPABLE) == 0) 1404 witness_output( 1405 "lock order reversal: (sleepable after non-sleepable)\n"); 1406 else if ((lock1->li_flags & LI_SLEEPABLE) == 0 1407 && lock == &Giant.lock_object) 1408 witness_output( 1409 "lock order reversal: (Giant after non-sleepable)\n"); 1410 else 1411 witness_output("lock order reversal:\n"); 1412 1413 /* 1414 * Try to locate an earlier lock with 1415 * witness w in our list. 1416 */ 1417 do { 1418 lock2 = &lle->ll_children[i]; 1419 MPASS(lock2->li_lock != NULL); 1420 if (lock2->li_lock->lo_witness == w) 1421 break; 1422 if (i == 0 && lle->ll_next != NULL) { 1423 lle = lle->ll_next; 1424 i = lle->ll_count - 1; 1425 MPASS(i >= 0 && i < LOCK_NCHILDREN); 1426 } else 1427 i--; 1428 } while (i >= 0); 1429 if (i < 0) { 1430 witness_output(" 1st %p %s (%s, %s) @ %s:%d\n", 1431 lock1->li_lock, lock1->li_lock->lo_name, 1432 w1->w_name, w1->w_class->lc_name, 1433 fixup_filename(lock1->li_file), 1434 lock1->li_line); 1435 witness_output(" 2nd %p %s (%s, %s) @ %s:%d\n", 1436 lock, lock->lo_name, w->w_name, 1437 w->w_class->lc_name, fixup_filename(file), 1438 line); 1439 } else { 1440 struct witness *w2 = lock2->li_lock->lo_witness; 1441 1442 witness_output(" 1st %p %s (%s, %s) @ %s:%d\n", 1443 lock2->li_lock, lock2->li_lock->lo_name, 1444 w2->w_name, w2->w_class->lc_name, 1445 fixup_filename(lock2->li_file), 1446 lock2->li_line); 1447 witness_output(" 2nd %p %s (%s, %s) @ %s:%d\n", 1448 lock1->li_lock, lock1->li_lock->lo_name, 1449 w1->w_name, w1->w_class->lc_name, 1450 fixup_filename(lock1->li_file), 1451 lock1->li_line); 1452 witness_output(" 3rd %p %s (%s, %s) @ %s:%d\n", lock, 1453 lock->lo_name, w->w_name, 1454 w->w_class->lc_name, fixup_filename(file), 1455 line); 1456 } 1457 if (trace) { 1458 char buf[64]; 1459 struct sbuf sb; 1460 1461 sbuf_new(&sb, buf, sizeof(buf), SBUF_FIXEDLEN); 1462 sbuf_set_drain(&sb, witness_output_drain, 1463 NULL); 1464 1465 if (pstackv) { 1466 sbuf_printf(&sb, 1467 "lock order %s -> %s established at:\n", 1468 w->w_name, w1->w_name); 1469 stack_sbuf_print_flags(&sb, &pstack, 1470 M_NOWAIT, STACK_SBUF_FMT_LONG); 1471 } 1472 1473 sbuf_printf(&sb, 1474 "lock order %s -> %s attempted at:\n", 1475 w1->w_name, w->w_name); 1476 stack_save(&pstack); 1477 stack_sbuf_print_flags(&sb, &pstack, M_NOWAIT, 1478 STACK_SBUF_FMT_LONG); 1479 1480 sbuf_finish(&sb); 1481 sbuf_delete(&sb); 1482 } 1483 witness_enter_debugger(__func__); 1484 return; 1485 } 1486 } 1487 1488 /* 1489 * If requested, build a new lock order. However, don't build a new 1490 * relationship between a sleepable lock and Giant if it is in the 1491 * wrong direction. The correct lock order is that sleepable locks 1492 * always come before Giant. 1493 */ 1494 if (flags & LOP_NEWORDER && 1495 !(plock->li_lock == &Giant.lock_object && 1496 (lock->lo_flags & LO_SLEEPABLE) != 0 && 1497 (flags & LOP_NOSLEEP) == 0)) { 1498 CTR3(KTR_WITNESS, "%s: adding %s as a child of %s", __func__, 1499 w->w_name, plock->li_lock->lo_witness->w_name); 1500 itismychild(plock->li_lock->lo_witness, w); 1501 } 1502 out: 1503 mtx_unlock_spin(&w_mtx); 1504 } 1505 1506 void 1507 witness_lock(struct lock_object *lock, int flags, const char *file, int line) 1508 { 1509 struct lock_list_entry **lock_list, *lle; 1510 struct lock_instance *instance; 1511 struct witness *w; 1512 struct thread *td; 1513 1514 if (witness_cold || witness_watch == -1 || lock->lo_witness == NULL || 1515 KERNEL_PANICKED()) 1516 return; 1517 w = lock->lo_witness; 1518 td = curthread; 1519 1520 /* Determine lock list for this lock. */ 1521 if (LOCK_CLASS(lock)->lc_flags & LC_SLEEPLOCK) 1522 lock_list = &td->td_sleeplocks; 1523 else 1524 lock_list = PCPU_PTR(spinlocks); 1525 1526 /* Check to see if we are recursing on a lock we already own. */ 1527 instance = find_instance(*lock_list, lock); 1528 if (instance != NULL) { 1529 instance->li_flags++; 1530 CTR4(KTR_WITNESS, "%s: pid %d recursed on %s r=%d", __func__, 1531 td->td_proc->p_pid, lock->lo_name, 1532 instance->li_flags & LI_RECURSEMASK); 1533 instance->li_file = file; 1534 instance->li_line = line; 1535 return; 1536 } 1537 1538 /* Update per-witness last file and line acquire. */ 1539 w->w_file = file; 1540 w->w_line = line; 1541 1542 /* Find the next open lock instance in the list and fill it. */ 1543 lle = *lock_list; 1544 if (lle == NULL || lle->ll_count == LOCK_NCHILDREN) { 1545 lle = witness_lock_list_get(); 1546 if (lle == NULL) 1547 return; 1548 lle->ll_next = *lock_list; 1549 CTR3(KTR_WITNESS, "%s: pid %d added lle %p", __func__, 1550 td->td_proc->p_pid, lle); 1551 *lock_list = lle; 1552 } 1553 instance = &lle->ll_children[lle->ll_count++]; 1554 instance->li_lock = lock; 1555 instance->li_line = line; 1556 instance->li_file = file; 1557 instance->li_flags = 0; 1558 if ((flags & LOP_EXCLUSIVE) != 0) 1559 instance->li_flags |= LI_EXCLUSIVE; 1560 if ((lock->lo_flags & LO_SLEEPABLE) != 0 && (flags & LOP_NOSLEEP) == 0) 1561 instance->li_flags |= LI_SLEEPABLE; 1562 CTR4(KTR_WITNESS, "%s: pid %d added %s as lle[%d]", __func__, 1563 td->td_proc->p_pid, lock->lo_name, lle->ll_count - 1); 1564 } 1565 1566 void 1567 witness_upgrade(struct lock_object *lock, int flags, const char *file, int line) 1568 { 1569 struct lock_instance *instance; 1570 struct lock_class *class; 1571 1572 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); 1573 if (lock->lo_witness == NULL || witness_watch == -1 || KERNEL_PANICKED()) 1574 return; 1575 class = LOCK_CLASS(lock); 1576 if (witness_watch) { 1577 if ((lock->lo_flags & LO_UPGRADABLE) == 0) 1578 kassert_panic( 1579 "upgrade of non-upgradable lock (%s) %s @ %s:%d", 1580 class->lc_name, lock->lo_name, 1581 fixup_filename(file), line); 1582 if ((class->lc_flags & LC_SLEEPLOCK) == 0) 1583 kassert_panic( 1584 "upgrade of non-sleep lock (%s) %s @ %s:%d", 1585 class->lc_name, lock->lo_name, 1586 fixup_filename(file), line); 1587 } 1588 instance = find_instance(curthread->td_sleeplocks, lock); 1589 if (instance == NULL) { 1590 kassert_panic("upgrade of unlocked lock (%s) %s @ %s:%d", 1591 class->lc_name, lock->lo_name, 1592 fixup_filename(file), line); 1593 return; 1594 } 1595 if (witness_watch) { 1596 if ((instance->li_flags & LI_EXCLUSIVE) != 0) 1597 kassert_panic( 1598 "upgrade of exclusive lock (%s) %s @ %s:%d", 1599 class->lc_name, lock->lo_name, 1600 fixup_filename(file), line); 1601 if ((instance->li_flags & LI_RECURSEMASK) != 0) 1602 kassert_panic( 1603 "upgrade of recursed lock (%s) %s r=%d @ %s:%d", 1604 class->lc_name, lock->lo_name, 1605 instance->li_flags & LI_RECURSEMASK, 1606 fixup_filename(file), line); 1607 } 1608 instance->li_flags |= LI_EXCLUSIVE; 1609 } 1610 1611 void 1612 witness_downgrade(struct lock_object *lock, int flags, const char *file, 1613 int line) 1614 { 1615 struct lock_instance *instance; 1616 struct lock_class *class; 1617 1618 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); 1619 if (lock->lo_witness == NULL || witness_watch == -1 || KERNEL_PANICKED()) 1620 return; 1621 class = LOCK_CLASS(lock); 1622 if (witness_watch) { 1623 if ((lock->lo_flags & LO_UPGRADABLE) == 0) 1624 kassert_panic( 1625 "downgrade of non-upgradable lock (%s) %s @ %s:%d", 1626 class->lc_name, lock->lo_name, 1627 fixup_filename(file), line); 1628 if ((class->lc_flags & LC_SLEEPLOCK) == 0) 1629 kassert_panic( 1630 "downgrade of non-sleep lock (%s) %s @ %s:%d", 1631 class->lc_name, lock->lo_name, 1632 fixup_filename(file), line); 1633 } 1634 instance = find_instance(curthread->td_sleeplocks, lock); 1635 if (instance == NULL) { 1636 kassert_panic("downgrade of unlocked lock (%s) %s @ %s:%d", 1637 class->lc_name, lock->lo_name, 1638 fixup_filename(file), line); 1639 return; 1640 } 1641 if (witness_watch) { 1642 if ((instance->li_flags & LI_EXCLUSIVE) == 0) 1643 kassert_panic( 1644 "downgrade of shared lock (%s) %s @ %s:%d", 1645 class->lc_name, lock->lo_name, 1646 fixup_filename(file), line); 1647 if ((instance->li_flags & LI_RECURSEMASK) != 0) 1648 kassert_panic( 1649 "downgrade of recursed lock (%s) %s r=%d @ %s:%d", 1650 class->lc_name, lock->lo_name, 1651 instance->li_flags & LI_RECURSEMASK, 1652 fixup_filename(file), line); 1653 } 1654 instance->li_flags &= ~LI_EXCLUSIVE; 1655 } 1656 1657 void 1658 witness_unlock(struct lock_object *lock, int flags, const char *file, int line) 1659 { 1660 struct lock_list_entry **lock_list, *lle; 1661 struct lock_instance *instance; 1662 struct lock_class *class; 1663 struct thread *td; 1664 register_t s; 1665 int i, j; 1666 1667 if (witness_cold || lock->lo_witness == NULL || KERNEL_PANICKED()) 1668 return; 1669 td = curthread; 1670 class = LOCK_CLASS(lock); 1671 1672 /* Find lock instance associated with this lock. */ 1673 if (class->lc_flags & LC_SLEEPLOCK) 1674 lock_list = &td->td_sleeplocks; 1675 else 1676 lock_list = PCPU_PTR(spinlocks); 1677 lle = *lock_list; 1678 for (; *lock_list != NULL; lock_list = &(*lock_list)->ll_next) 1679 for (i = 0; i < (*lock_list)->ll_count; i++) { 1680 instance = &(*lock_list)->ll_children[i]; 1681 if (instance->li_lock == lock) 1682 goto found; 1683 } 1684 1685 /* 1686 * When disabling WITNESS through witness_watch we could end up in 1687 * having registered locks in the td_sleeplocks queue. 1688 * We have to make sure we flush these queues, so just search for 1689 * eventual register locks and remove them. 1690 */ 1691 if (witness_watch > 0) { 1692 kassert_panic("lock (%s) %s not locked @ %s:%d", class->lc_name, 1693 lock->lo_name, fixup_filename(file), line); 1694 return; 1695 } else { 1696 return; 1697 } 1698 found: 1699 1700 /* First, check for shared/exclusive mismatches. */ 1701 if ((instance->li_flags & LI_EXCLUSIVE) != 0 && witness_watch > 0 && 1702 (flags & LOP_EXCLUSIVE) == 0) { 1703 witness_output("shared unlock of (%s) %s @ %s:%d\n", 1704 class->lc_name, lock->lo_name, fixup_filename(file), line); 1705 witness_output("while exclusively locked from %s:%d\n", 1706 fixup_filename(instance->li_file), instance->li_line); 1707 kassert_panic("excl->ushare"); 1708 } 1709 if ((instance->li_flags & LI_EXCLUSIVE) == 0 && witness_watch > 0 && 1710 (flags & LOP_EXCLUSIVE) != 0) { 1711 witness_output("exclusive unlock of (%s) %s @ %s:%d\n", 1712 class->lc_name, lock->lo_name, fixup_filename(file), line); 1713 witness_output("while share locked from %s:%d\n", 1714 fixup_filename(instance->li_file), 1715 instance->li_line); 1716 kassert_panic("share->uexcl"); 1717 } 1718 /* If we are recursed, unrecurse. */ 1719 if ((instance->li_flags & LI_RECURSEMASK) > 0) { 1720 CTR4(KTR_WITNESS, "%s: pid %d unrecursed on %s r=%d", __func__, 1721 td->td_proc->p_pid, instance->li_lock->lo_name, 1722 instance->li_flags); 1723 instance->li_flags--; 1724 return; 1725 } 1726 /* The lock is now being dropped, check for NORELEASE flag */ 1727 if ((instance->li_flags & LI_NORELEASE) != 0 && witness_watch > 0) { 1728 witness_output("forbidden unlock of (%s) %s @ %s:%d\n", 1729 class->lc_name, lock->lo_name, fixup_filename(file), line); 1730 kassert_panic("lock marked norelease"); 1731 } 1732 1733 /* Otherwise, remove this item from the list. */ 1734 s = intr_disable(); 1735 CTR4(KTR_WITNESS, "%s: pid %d removed %s from lle[%d]", __func__, 1736 td->td_proc->p_pid, instance->li_lock->lo_name, 1737 (*lock_list)->ll_count - 1); 1738 for (j = i; j < (*lock_list)->ll_count - 1; j++) 1739 (*lock_list)->ll_children[j] = 1740 (*lock_list)->ll_children[j + 1]; 1741 (*lock_list)->ll_count--; 1742 intr_restore(s); 1743 1744 /* 1745 * In order to reduce contention on w_mtx, we want to keep always an 1746 * head object into lists so that frequent allocation from the 1747 * free witness pool (and subsequent locking) is avoided. 1748 * In order to maintain the current code simple, when the head 1749 * object is totally unloaded it means also that we do not have 1750 * further objects in the list, so the list ownership needs to be 1751 * hand over to another object if the current head needs to be freed. 1752 */ 1753 if ((*lock_list)->ll_count == 0) { 1754 if (*lock_list == lle) { 1755 if (lle->ll_next == NULL) 1756 return; 1757 } else 1758 lle = *lock_list; 1759 *lock_list = lle->ll_next; 1760 CTR3(KTR_WITNESS, "%s: pid %d removed lle %p", __func__, 1761 td->td_proc->p_pid, lle); 1762 witness_lock_list_free(lle); 1763 } 1764 } 1765 1766 void 1767 witness_thread_exit(struct thread *td) 1768 { 1769 struct lock_list_entry *lle; 1770 int i, n; 1771 1772 lle = td->td_sleeplocks; 1773 if (lle == NULL || KERNEL_PANICKED()) 1774 return; 1775 if (lle->ll_count != 0) { 1776 for (n = 0; lle != NULL; lle = lle->ll_next) 1777 for (i = lle->ll_count - 1; i >= 0; i--) { 1778 if (n == 0) 1779 witness_output( 1780 "Thread %p exiting with the following locks held:\n", td); 1781 n++; 1782 witness_list_lock(&lle->ll_children[i], 1783 witness_output); 1784 1785 } 1786 kassert_panic( 1787 "Thread %p cannot exit while holding sleeplocks\n", td); 1788 } 1789 witness_lock_list_free(lle); 1790 } 1791 1792 /* 1793 * Warn if any locks other than 'lock' are held. Flags can be passed in to 1794 * exempt Giant and sleepable locks from the checks as well. If any 1795 * non-exempt locks are held, then a supplied message is printed to the 1796 * output channel along with a list of the offending locks. If indicated in the 1797 * flags then a failure results in a panic as well. 1798 */ 1799 int 1800 witness_warn(int flags, struct lock_object *lock, const char *fmt, ...) 1801 { 1802 struct lock_list_entry *lock_list, *lle; 1803 struct lock_instance *lock1; 1804 struct thread *td; 1805 va_list ap; 1806 int i, n; 1807 1808 if (witness_cold || witness_watch < 1 || KERNEL_PANICKED()) 1809 return (0); 1810 n = 0; 1811 td = curthread; 1812 for (lle = td->td_sleeplocks; lle != NULL; lle = lle->ll_next) 1813 for (i = lle->ll_count - 1; i >= 0; i--) { 1814 lock1 = &lle->ll_children[i]; 1815 if (lock1->li_lock == lock) 1816 continue; 1817 if (flags & WARN_GIANTOK && 1818 lock1->li_lock == &Giant.lock_object) 1819 continue; 1820 if (flags & WARN_SLEEPOK && 1821 (lock1->li_flags & LI_SLEEPABLE) != 0) 1822 continue; 1823 if (n == 0) { 1824 va_start(ap, fmt); 1825 vprintf(fmt, ap); 1826 va_end(ap); 1827 printf(" with the following %slocks held:\n", 1828 (flags & WARN_SLEEPOK) != 0 ? 1829 "non-sleepable " : ""); 1830 } 1831 n++; 1832 witness_list_lock(lock1, printf); 1833 } 1834 1835 /* 1836 * Pin the thread in order to avoid problems with thread migration. 1837 * Once that all verifies are passed about spinlocks ownership, 1838 * the thread is in a safe path and it can be unpinned. 1839 */ 1840 sched_pin(); 1841 lock_list = PCPU_GET(spinlocks); 1842 if (lock_list != NULL && lock_list->ll_count != 0) { 1843 sched_unpin(); 1844 1845 /* 1846 * We should only have one spinlock and as long as 1847 * the flags cannot match for this locks class, 1848 * check if the first spinlock is the one curthread 1849 * should hold. 1850 */ 1851 lock1 = &lock_list->ll_children[lock_list->ll_count - 1]; 1852 if (lock_list->ll_count == 1 && lock_list->ll_next == NULL && 1853 lock1->li_lock == lock && n == 0) 1854 return (0); 1855 1856 va_start(ap, fmt); 1857 vprintf(fmt, ap); 1858 va_end(ap); 1859 printf(" with the following %slocks held:\n", 1860 (flags & WARN_SLEEPOK) != 0 ? "non-sleepable " : ""); 1861 n += witness_list_locks(&lock_list, printf); 1862 } else 1863 sched_unpin(); 1864 if (flags & WARN_PANIC && n) 1865 kassert_panic("%s", __func__); 1866 else 1867 witness_debugger(n, __func__); 1868 return (n); 1869 } 1870 1871 const char * 1872 witness_file(struct lock_object *lock) 1873 { 1874 struct witness *w; 1875 1876 if (witness_cold || witness_watch < 1 || lock->lo_witness == NULL) 1877 return ("?"); 1878 w = lock->lo_witness; 1879 return (w->w_file); 1880 } 1881 1882 int 1883 witness_line(struct lock_object *lock) 1884 { 1885 struct witness *w; 1886 1887 if (witness_cold || witness_watch < 1 || lock->lo_witness == NULL) 1888 return (0); 1889 w = lock->lo_witness; 1890 return (w->w_line); 1891 } 1892 1893 static struct witness * 1894 enroll(const char *description, struct lock_class *lock_class) 1895 { 1896 struct witness *w; 1897 1898 MPASS(description != NULL); 1899 1900 if (witness_watch == -1 || KERNEL_PANICKED()) 1901 return (NULL); 1902 if ((lock_class->lc_flags & LC_SPINLOCK)) { 1903 if (witness_skipspin) 1904 return (NULL); 1905 } else if ((lock_class->lc_flags & LC_SLEEPLOCK) == 0) { 1906 kassert_panic("lock class %s is not sleep or spin", 1907 lock_class->lc_name); 1908 return (NULL); 1909 } 1910 1911 mtx_lock_spin(&w_mtx); 1912 w = witness_hash_get(description); 1913 if (w) 1914 goto found; 1915 if ((w = witness_get()) == NULL) 1916 return (NULL); 1917 MPASS(strlen(description) < MAX_W_NAME); 1918 strcpy(w->w_name, description); 1919 w->w_class = lock_class; 1920 w->w_refcount = 1; 1921 STAILQ_INSERT_HEAD(&w_all, w, w_list); 1922 if (lock_class->lc_flags & LC_SPINLOCK) { 1923 STAILQ_INSERT_HEAD(&w_spin, w, w_typelist); 1924 w_spin_cnt++; 1925 } else if (lock_class->lc_flags & LC_SLEEPLOCK) { 1926 STAILQ_INSERT_HEAD(&w_sleep, w, w_typelist); 1927 w_sleep_cnt++; 1928 } 1929 1930 /* Insert new witness into the hash */ 1931 witness_hash_put(w); 1932 witness_increment_graph_generation(); 1933 mtx_unlock_spin(&w_mtx); 1934 return (w); 1935 found: 1936 w->w_refcount++; 1937 if (w->w_refcount == 1) 1938 w->w_class = lock_class; 1939 mtx_unlock_spin(&w_mtx); 1940 if (lock_class != w->w_class) 1941 kassert_panic( 1942 "lock (%s) %s does not match earlier (%s) lock", 1943 description, lock_class->lc_name, 1944 w->w_class->lc_name); 1945 return (w); 1946 } 1947 1948 static void 1949 depart(struct witness *w) 1950 { 1951 1952 MPASS(w->w_refcount == 0); 1953 if (w->w_class->lc_flags & LC_SLEEPLOCK) { 1954 w_sleep_cnt--; 1955 } else { 1956 w_spin_cnt--; 1957 } 1958 /* 1959 * Set file to NULL as it may point into a loadable module. 1960 */ 1961 w->w_file = NULL; 1962 w->w_line = 0; 1963 witness_increment_graph_generation(); 1964 } 1965 1966 static void 1967 adopt(struct witness *parent, struct witness *child) 1968 { 1969 int pi, ci, i, j; 1970 1971 if (witness_cold == 0) 1972 mtx_assert(&w_mtx, MA_OWNED); 1973 1974 /* If the relationship is already known, there's no work to be done. */ 1975 if (isitmychild(parent, child)) 1976 return; 1977 1978 /* When the structure of the graph changes, bump up the generation. */ 1979 witness_increment_graph_generation(); 1980 1981 /* 1982 * The hard part ... create the direct relationship, then propagate all 1983 * indirect relationships. 1984 */ 1985 pi = parent->w_index; 1986 ci = child->w_index; 1987 WITNESS_INDEX_ASSERT(pi); 1988 WITNESS_INDEX_ASSERT(ci); 1989 MPASS(pi != ci); 1990 w_rmatrix[pi][ci] |= WITNESS_PARENT; 1991 w_rmatrix[ci][pi] |= WITNESS_CHILD; 1992 1993 /* 1994 * If parent was not already an ancestor of child, 1995 * then we increment the descendant and ancestor counters. 1996 */ 1997 if ((w_rmatrix[pi][ci] & WITNESS_ANCESTOR) == 0) { 1998 parent->w_num_descendants++; 1999 child->w_num_ancestors++; 2000 } 2001 2002 /* 2003 * Find each ancestor of 'pi'. Note that 'pi' itself is counted as 2004 * an ancestor of 'pi' during this loop. 2005 */ 2006 for (i = 1; i <= w_max_used_index; i++) { 2007 if ((w_rmatrix[i][pi] & WITNESS_ANCESTOR_MASK) == 0 && 2008 (i != pi)) 2009 continue; 2010 2011 /* Find each descendant of 'i' and mark it as a descendant. */ 2012 for (j = 1; j <= w_max_used_index; j++) { 2013 /* 2014 * Skip children that are already marked as 2015 * descendants of 'i'. 2016 */ 2017 if (w_rmatrix[i][j] & WITNESS_ANCESTOR_MASK) 2018 continue; 2019 2020 /* 2021 * We are only interested in descendants of 'ci'. Note 2022 * that 'ci' itself is counted as a descendant of 'ci'. 2023 */ 2024 if ((w_rmatrix[ci][j] & WITNESS_ANCESTOR_MASK) == 0 && 2025 (j != ci)) 2026 continue; 2027 w_rmatrix[i][j] |= WITNESS_ANCESTOR; 2028 w_rmatrix[j][i] |= WITNESS_DESCENDANT; 2029 w_data[i].w_num_descendants++; 2030 w_data[j].w_num_ancestors++; 2031 2032 /* 2033 * Make sure we aren't marking a node as both an 2034 * ancestor and descendant. We should have caught 2035 * this as a lock order reversal earlier. 2036 */ 2037 if ((w_rmatrix[i][j] & WITNESS_ANCESTOR_MASK) && 2038 (w_rmatrix[i][j] & WITNESS_DESCENDANT_MASK)) { 2039 printf("witness rmatrix paradox! [%d][%d]=%d " 2040 "both ancestor and descendant\n", 2041 i, j, w_rmatrix[i][j]); 2042 kdb_backtrace(); 2043 printf("Witness disabled.\n"); 2044 witness_watch = -1; 2045 } 2046 if ((w_rmatrix[j][i] & WITNESS_ANCESTOR_MASK) && 2047 (w_rmatrix[j][i] & WITNESS_DESCENDANT_MASK)) { 2048 printf("witness rmatrix paradox! [%d][%d]=%d " 2049 "both ancestor and descendant\n", 2050 j, i, w_rmatrix[j][i]); 2051 kdb_backtrace(); 2052 printf("Witness disabled.\n"); 2053 witness_watch = -1; 2054 } 2055 } 2056 } 2057 } 2058 2059 static void 2060 itismychild(struct witness *parent, struct witness *child) 2061 { 2062 int unlocked; 2063 2064 MPASS(child != NULL && parent != NULL); 2065 if (witness_cold == 0) 2066 mtx_assert(&w_mtx, MA_OWNED); 2067 2068 if (!witness_lock_type_equal(parent, child)) { 2069 if (witness_cold == 0) { 2070 unlocked = 1; 2071 mtx_unlock_spin(&w_mtx); 2072 } else { 2073 unlocked = 0; 2074 } 2075 kassert_panic( 2076 "%s: parent \"%s\" (%s) and child \"%s\" (%s) are not " 2077 "the same lock type", __func__, parent->w_name, 2078 parent->w_class->lc_name, child->w_name, 2079 child->w_class->lc_name); 2080 if (unlocked) 2081 mtx_lock_spin(&w_mtx); 2082 } 2083 adopt(parent, child); 2084 } 2085 2086 /* 2087 * Generic code for the isitmy*() functions. The rmask parameter is the 2088 * expected relationship of w1 to w2. 2089 */ 2090 static int 2091 _isitmyx(struct witness *w1, struct witness *w2, int rmask, const char *fname) 2092 { 2093 unsigned char r1, r2; 2094 int i1, i2; 2095 2096 i1 = w1->w_index; 2097 i2 = w2->w_index; 2098 WITNESS_INDEX_ASSERT(i1); 2099 WITNESS_INDEX_ASSERT(i2); 2100 r1 = w_rmatrix[i1][i2] & WITNESS_RELATED_MASK; 2101 r2 = w_rmatrix[i2][i1] & WITNESS_RELATED_MASK; 2102 2103 /* The flags on one better be the inverse of the flags on the other */ 2104 if (!((WITNESS_ATOD(r1) == r2 && WITNESS_DTOA(r2) == r1) || 2105 (WITNESS_DTOA(r1) == r2 && WITNESS_ATOD(r2) == r1))) { 2106 /* Don't squawk if we're potentially racing with an update. */ 2107 if (!mtx_owned(&w_mtx)) 2108 return (0); 2109 printf("%s: rmatrix mismatch between %s (index %d) and %s " 2110 "(index %d): w_rmatrix[%d][%d] == %hhx but " 2111 "w_rmatrix[%d][%d] == %hhx\n", 2112 fname, w1->w_name, i1, w2->w_name, i2, i1, i2, r1, 2113 i2, i1, r2); 2114 kdb_backtrace(); 2115 printf("Witness disabled.\n"); 2116 witness_watch = -1; 2117 } 2118 return (r1 & rmask); 2119 } 2120 2121 /* 2122 * Checks if @child is a direct child of @parent. 2123 */ 2124 static int 2125 isitmychild(struct witness *parent, struct witness *child) 2126 { 2127 2128 return (_isitmyx(parent, child, WITNESS_PARENT, __func__)); 2129 } 2130 2131 /* 2132 * Checks if @descendant is a direct or inderect descendant of @ancestor. 2133 */ 2134 static int 2135 isitmydescendant(struct witness *ancestor, struct witness *descendant) 2136 { 2137 2138 return (_isitmyx(ancestor, descendant, WITNESS_ANCESTOR_MASK, 2139 __func__)); 2140 } 2141 2142 static int 2143 blessed(struct witness *w1, struct witness *w2) 2144 { 2145 int i; 2146 struct witness_blessed *b; 2147 2148 for (i = 0; i < nitems(blessed_list); i++) { 2149 b = &blessed_list[i]; 2150 if (strcmp(w1->w_name, b->b_lock1) == 0) { 2151 if (strcmp(w2->w_name, b->b_lock2) == 0) 2152 return (1); 2153 continue; 2154 } 2155 if (strcmp(w1->w_name, b->b_lock2) == 0) 2156 if (strcmp(w2->w_name, b->b_lock1) == 0) 2157 return (1); 2158 } 2159 return (0); 2160 } 2161 2162 static struct witness * 2163 witness_get(void) 2164 { 2165 struct witness *w; 2166 int index; 2167 2168 if (witness_cold == 0) 2169 mtx_assert(&w_mtx, MA_OWNED); 2170 2171 if (witness_watch == -1) { 2172 mtx_unlock_spin(&w_mtx); 2173 return (NULL); 2174 } 2175 if (STAILQ_EMPTY(&w_free)) { 2176 witness_watch = -1; 2177 mtx_unlock_spin(&w_mtx); 2178 printf("WITNESS: unable to allocate a new witness object\n"); 2179 return (NULL); 2180 } 2181 w = STAILQ_FIRST(&w_free); 2182 STAILQ_REMOVE_HEAD(&w_free, w_list); 2183 w_free_cnt--; 2184 index = w->w_index; 2185 MPASS(index > 0 && index == w_max_used_index+1 && 2186 index < witness_count); 2187 bzero(w, sizeof(*w)); 2188 w->w_index = index; 2189 if (index > w_max_used_index) 2190 w_max_used_index = index; 2191 return (w); 2192 } 2193 2194 static void 2195 witness_free(struct witness *w) 2196 { 2197 2198 STAILQ_INSERT_HEAD(&w_free, w, w_list); 2199 w_free_cnt++; 2200 } 2201 2202 static struct lock_list_entry * 2203 witness_lock_list_get(void) 2204 { 2205 struct lock_list_entry *lle; 2206 2207 if (witness_watch == -1) 2208 return (NULL); 2209 mtx_lock_spin(&w_mtx); 2210 lle = w_lock_list_free; 2211 if (lle == NULL) { 2212 witness_watch = -1; 2213 mtx_unlock_spin(&w_mtx); 2214 printf("%s: witness exhausted\n", __func__); 2215 return (NULL); 2216 } 2217 w_lock_list_free = lle->ll_next; 2218 mtx_unlock_spin(&w_mtx); 2219 bzero(lle, sizeof(*lle)); 2220 return (lle); 2221 } 2222 2223 static void 2224 witness_lock_list_free(struct lock_list_entry *lle) 2225 { 2226 2227 mtx_lock_spin(&w_mtx); 2228 lle->ll_next = w_lock_list_free; 2229 w_lock_list_free = lle; 2230 mtx_unlock_spin(&w_mtx); 2231 } 2232 2233 static struct lock_instance * 2234 find_instance(struct lock_list_entry *list, const struct lock_object *lock) 2235 { 2236 struct lock_list_entry *lle; 2237 struct lock_instance *instance; 2238 int i; 2239 2240 for (lle = list; lle != NULL; lle = lle->ll_next) 2241 for (i = lle->ll_count - 1; i >= 0; i--) { 2242 instance = &lle->ll_children[i]; 2243 if (instance->li_lock == lock) 2244 return (instance); 2245 } 2246 return (NULL); 2247 } 2248 2249 static void 2250 witness_list_lock(struct lock_instance *instance, 2251 int (*prnt)(const char *fmt, ...)) 2252 { 2253 struct lock_object *lock; 2254 2255 lock = instance->li_lock; 2256 prnt("%s %s %s", (instance->li_flags & LI_EXCLUSIVE) != 0 ? 2257 "exclusive" : "shared", LOCK_CLASS(lock)->lc_name, lock->lo_name); 2258 if (lock->lo_witness->w_name != lock->lo_name) 2259 prnt(" (%s)", lock->lo_witness->w_name); 2260 prnt(" r = %d (%p) locked @ %s:%d\n", 2261 instance->li_flags & LI_RECURSEMASK, lock, 2262 fixup_filename(instance->li_file), instance->li_line); 2263 } 2264 2265 static int 2266 witness_output(const char *fmt, ...) 2267 { 2268 va_list ap; 2269 int ret; 2270 2271 va_start(ap, fmt); 2272 ret = witness_voutput(fmt, ap); 2273 va_end(ap); 2274 return (ret); 2275 } 2276 2277 static int 2278 witness_voutput(const char *fmt, va_list ap) 2279 { 2280 int ret; 2281 2282 ret = 0; 2283 switch (witness_channel) { 2284 case WITNESS_CONSOLE: 2285 ret = vprintf(fmt, ap); 2286 break; 2287 case WITNESS_LOG: 2288 vlog(LOG_NOTICE, fmt, ap); 2289 break; 2290 case WITNESS_NONE: 2291 break; 2292 } 2293 return (ret); 2294 } 2295 2296 #ifdef DDB 2297 static int 2298 witness_thread_has_locks(struct thread *td) 2299 { 2300 2301 if (td->td_sleeplocks == NULL) 2302 return (0); 2303 return (td->td_sleeplocks->ll_count != 0); 2304 } 2305 2306 static int 2307 witness_proc_has_locks(struct proc *p) 2308 { 2309 struct thread *td; 2310 2311 FOREACH_THREAD_IN_PROC(p, td) { 2312 if (witness_thread_has_locks(td)) 2313 return (1); 2314 } 2315 return (0); 2316 } 2317 #endif 2318 2319 int 2320 witness_list_locks(struct lock_list_entry **lock_list, 2321 int (*prnt)(const char *fmt, ...)) 2322 { 2323 struct lock_list_entry *lle; 2324 int i, nheld; 2325 2326 nheld = 0; 2327 for (lle = *lock_list; lle != NULL; lle = lle->ll_next) 2328 for (i = lle->ll_count - 1; i >= 0; i--) { 2329 witness_list_lock(&lle->ll_children[i], prnt); 2330 nheld++; 2331 } 2332 return (nheld); 2333 } 2334 2335 /* 2336 * This is a bit risky at best. We call this function when we have timed 2337 * out acquiring a spin lock, and we assume that the other CPU is stuck 2338 * with this lock held. So, we go groveling around in the other CPU's 2339 * per-cpu data to try to find the lock instance for this spin lock to 2340 * see when it was last acquired. 2341 */ 2342 void 2343 witness_display_spinlock(struct lock_object *lock, struct thread *owner, 2344 int (*prnt)(const char *fmt, ...)) 2345 { 2346 struct lock_instance *instance; 2347 struct pcpu *pc; 2348 2349 if (owner->td_critnest == 0 || owner->td_oncpu == NOCPU) 2350 return; 2351 pc = pcpu_find(owner->td_oncpu); 2352 instance = find_instance(pc->pc_spinlocks, lock); 2353 if (instance != NULL) 2354 witness_list_lock(instance, prnt); 2355 } 2356 2357 void 2358 witness_save(struct lock_object *lock, const char **filep, int *linep) 2359 { 2360 struct lock_list_entry *lock_list; 2361 struct lock_instance *instance; 2362 struct lock_class *class; 2363 2364 /* Initialize for KMSAN's benefit. */ 2365 *filep = NULL; 2366 *linep = 0; 2367 2368 /* 2369 * This function is used independently in locking code to deal with 2370 * Giant, SCHEDULER_STOPPED() check can be removed here after Giant 2371 * is gone. 2372 */ 2373 if (SCHEDULER_STOPPED()) 2374 return; 2375 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); 2376 if (lock->lo_witness == NULL || witness_watch == -1 || KERNEL_PANICKED()) 2377 return; 2378 class = LOCK_CLASS(lock); 2379 if (class->lc_flags & LC_SLEEPLOCK) 2380 lock_list = curthread->td_sleeplocks; 2381 else { 2382 if (witness_skipspin) 2383 return; 2384 lock_list = PCPU_GET(spinlocks); 2385 } 2386 instance = find_instance(lock_list, lock); 2387 if (instance == NULL) { 2388 kassert_panic("%s: lock (%s) %s not locked", __func__, 2389 class->lc_name, lock->lo_name); 2390 return; 2391 } 2392 *filep = instance->li_file; 2393 *linep = instance->li_line; 2394 } 2395 2396 void 2397 witness_restore(struct lock_object *lock, const char *file, int line) 2398 { 2399 struct lock_list_entry *lock_list; 2400 struct lock_instance *instance; 2401 struct lock_class *class; 2402 2403 /* 2404 * This function is used independently in locking code to deal with 2405 * Giant, SCHEDULER_STOPPED() check can be removed here after Giant 2406 * is gone. 2407 */ 2408 if (SCHEDULER_STOPPED()) 2409 return; 2410 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); 2411 if (lock->lo_witness == NULL || witness_watch == -1 || KERNEL_PANICKED()) 2412 return; 2413 class = LOCK_CLASS(lock); 2414 if (class->lc_flags & LC_SLEEPLOCK) 2415 lock_list = curthread->td_sleeplocks; 2416 else { 2417 if (witness_skipspin) 2418 return; 2419 lock_list = PCPU_GET(spinlocks); 2420 } 2421 instance = find_instance(lock_list, lock); 2422 if (instance == NULL) 2423 kassert_panic("%s: lock (%s) %s not locked", __func__, 2424 class->lc_name, lock->lo_name); 2425 lock->lo_witness->w_file = file; 2426 lock->lo_witness->w_line = line; 2427 if (instance == NULL) 2428 return; 2429 instance->li_file = file; 2430 instance->li_line = line; 2431 } 2432 2433 static bool 2434 witness_find_instance(const struct lock_object *lock, 2435 struct lock_instance **instance) 2436 { 2437 #ifdef INVARIANT_SUPPORT 2438 struct lock_class *class; 2439 2440 if (lock->lo_witness == NULL || witness_watch < 1 || KERNEL_PANICKED()) 2441 return (false); 2442 class = LOCK_CLASS(lock); 2443 if ((class->lc_flags & LC_SLEEPLOCK) != 0) { 2444 *instance = find_instance(curthread->td_sleeplocks, lock); 2445 return (true); 2446 } else if ((class->lc_flags & LC_SPINLOCK) != 0) { 2447 *instance = find_instance(PCPU_GET(spinlocks), lock); 2448 return (true); 2449 } else { 2450 kassert_panic("Lock (%s) %s is not sleep or spin!", 2451 class->lc_name, lock->lo_name); 2452 return (false); 2453 } 2454 #else 2455 return (false); 2456 #endif 2457 } 2458 2459 void 2460 witness_assert(const struct lock_object *lock, int flags, const char *file, 2461 int line) 2462 { 2463 #ifdef INVARIANT_SUPPORT 2464 struct lock_instance *instance; 2465 struct lock_class *class; 2466 2467 if (!witness_find_instance(lock, &instance)) 2468 return; 2469 class = LOCK_CLASS(lock); 2470 switch (flags) { 2471 case LA_UNLOCKED: 2472 if (instance != NULL) 2473 kassert_panic("Lock (%s) %s locked @ %s:%d.", 2474 class->lc_name, lock->lo_name, 2475 fixup_filename(file), line); 2476 break; 2477 case LA_LOCKED: 2478 case LA_LOCKED | LA_RECURSED: 2479 case LA_LOCKED | LA_NOTRECURSED: 2480 case LA_SLOCKED: 2481 case LA_SLOCKED | LA_RECURSED: 2482 case LA_SLOCKED | LA_NOTRECURSED: 2483 case LA_XLOCKED: 2484 case LA_XLOCKED | LA_RECURSED: 2485 case LA_XLOCKED | LA_NOTRECURSED: 2486 if (instance == NULL) { 2487 kassert_panic("Lock (%s) %s not locked @ %s:%d.", 2488 class->lc_name, lock->lo_name, 2489 fixup_filename(file), line); 2490 break; 2491 } 2492 if ((flags & LA_XLOCKED) != 0 && 2493 (instance->li_flags & LI_EXCLUSIVE) == 0) 2494 kassert_panic( 2495 "Lock (%s) %s not exclusively locked @ %s:%d.", 2496 class->lc_name, lock->lo_name, 2497 fixup_filename(file), line); 2498 if ((flags & LA_SLOCKED) != 0 && 2499 (instance->li_flags & LI_EXCLUSIVE) != 0) 2500 kassert_panic( 2501 "Lock (%s) %s exclusively locked @ %s:%d.", 2502 class->lc_name, lock->lo_name, 2503 fixup_filename(file), line); 2504 if ((flags & LA_RECURSED) != 0 && 2505 (instance->li_flags & LI_RECURSEMASK) == 0) 2506 kassert_panic("Lock (%s) %s not recursed @ %s:%d.", 2507 class->lc_name, lock->lo_name, 2508 fixup_filename(file), line); 2509 if ((flags & LA_NOTRECURSED) != 0 && 2510 (instance->li_flags & LI_RECURSEMASK) != 0) 2511 kassert_panic("Lock (%s) %s recursed @ %s:%d.", 2512 class->lc_name, lock->lo_name, 2513 fixup_filename(file), line); 2514 break; 2515 default: 2516 kassert_panic("Invalid lock assertion at %s:%d.", 2517 fixup_filename(file), line); 2518 } 2519 #endif /* INVARIANT_SUPPORT */ 2520 } 2521 2522 /* 2523 * Checks the ownership of the lock by curthread, consulting the witness list. 2524 * Returns: 2525 * 0 if witness is disabled or did not work 2526 * -1 if not owned 2527 * 1 if owned 2528 */ 2529 int 2530 witness_is_owned(const struct lock_object *lock) 2531 { 2532 #ifdef INVARIANT_SUPPORT 2533 struct lock_instance *instance; 2534 2535 if (!witness_find_instance(lock, &instance)) 2536 return (0); 2537 return (instance == NULL ? -1 : 1); 2538 #else 2539 return (0); 2540 #endif 2541 } 2542 2543 static void 2544 witness_setflag(struct lock_object *lock, int flag, int set) 2545 { 2546 struct lock_list_entry *lock_list; 2547 struct lock_instance *instance; 2548 struct lock_class *class; 2549 2550 if (lock->lo_witness == NULL || witness_watch == -1 || KERNEL_PANICKED()) 2551 return; 2552 class = LOCK_CLASS(lock); 2553 if (class->lc_flags & LC_SLEEPLOCK) 2554 lock_list = curthread->td_sleeplocks; 2555 else { 2556 if (witness_skipspin) 2557 return; 2558 lock_list = PCPU_GET(spinlocks); 2559 } 2560 instance = find_instance(lock_list, lock); 2561 if (instance == NULL) { 2562 kassert_panic("%s: lock (%s) %s not locked", __func__, 2563 class->lc_name, lock->lo_name); 2564 return; 2565 } 2566 2567 if (set) 2568 instance->li_flags |= flag; 2569 else 2570 instance->li_flags &= ~flag; 2571 } 2572 2573 void 2574 witness_norelease(struct lock_object *lock) 2575 { 2576 2577 witness_setflag(lock, LI_NORELEASE, 1); 2578 } 2579 2580 void 2581 witness_releaseok(struct lock_object *lock) 2582 { 2583 2584 witness_setflag(lock, LI_NORELEASE, 0); 2585 } 2586 2587 #ifdef DDB 2588 static void 2589 witness_ddb_list(struct thread *td) 2590 { 2591 2592 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); 2593 KASSERT(kdb_active, ("%s: not in the debugger", __func__)); 2594 2595 if (witness_watch < 1) 2596 return; 2597 2598 witness_list_locks(&td->td_sleeplocks, db_printf); 2599 2600 /* 2601 * We only handle spinlocks if td == curthread. This is somewhat broken 2602 * if td is currently executing on some other CPU and holds spin locks 2603 * as we won't display those locks. If we had a MI way of getting 2604 * the per-cpu data for a given cpu then we could use 2605 * td->td_oncpu to get the list of spinlocks for this thread 2606 * and "fix" this. 2607 * 2608 * That still wouldn't really fix this unless we locked the scheduler 2609 * lock or stopped the other CPU to make sure it wasn't changing the 2610 * list out from under us. It is probably best to just not try to 2611 * handle threads on other CPU's for now. 2612 */ 2613 if (td == curthread && PCPU_GET(spinlocks) != NULL) 2614 witness_list_locks(PCPU_PTR(spinlocks), db_printf); 2615 } 2616 2617 DB_SHOW_COMMAND(locks, db_witness_list) 2618 { 2619 struct thread *td; 2620 2621 if (have_addr) 2622 td = db_lookup_thread(addr, true); 2623 else 2624 td = kdb_thread; 2625 witness_ddb_list(td); 2626 } 2627 2628 DB_SHOW_ALL_COMMAND(locks, db_witness_list_all) 2629 { 2630 struct thread *td; 2631 struct proc *p; 2632 2633 /* 2634 * It would be nice to list only threads and processes that actually 2635 * held sleep locks, but that information is currently not exported 2636 * by WITNESS. 2637 */ 2638 FOREACH_PROC_IN_SYSTEM(p) { 2639 if (!witness_proc_has_locks(p)) 2640 continue; 2641 FOREACH_THREAD_IN_PROC(p, td) { 2642 if (!witness_thread_has_locks(td)) 2643 continue; 2644 db_printf("Process %d (%s) thread %p (%d)\n", p->p_pid, 2645 p->p_comm, td, td->td_tid); 2646 witness_ddb_list(td); 2647 if (db_pager_quit) 2648 return; 2649 } 2650 } 2651 } 2652 DB_SHOW_ALIAS_FLAGS(alllocks, db_witness_list_all, DB_CMD_MEMSAFE); 2653 2654 DB_SHOW_COMMAND_FLAGS(witness, db_witness_display, DB_CMD_MEMSAFE) 2655 { 2656 2657 witness_ddb_display(db_printf); 2658 } 2659 #endif 2660 2661 static void 2662 sbuf_print_witness_badstacks(struct sbuf *sb, size_t *oldidx) 2663 { 2664 struct witness_lock_order_data *data1, *data2, *tmp_data1, *tmp_data2; 2665 struct witness *tmp_w1, *tmp_w2, *w1, *w2; 2666 int generation, i, j; 2667 2668 tmp_data1 = NULL; 2669 tmp_data2 = NULL; 2670 tmp_w1 = NULL; 2671 tmp_w2 = NULL; 2672 2673 /* Allocate and init temporary storage space. */ 2674 tmp_w1 = malloc(sizeof(struct witness), M_TEMP, M_WAITOK | M_ZERO); 2675 tmp_w2 = malloc(sizeof(struct witness), M_TEMP, M_WAITOK | M_ZERO); 2676 tmp_data1 = malloc(sizeof(struct witness_lock_order_data), M_TEMP, 2677 M_WAITOK | M_ZERO); 2678 tmp_data2 = malloc(sizeof(struct witness_lock_order_data), M_TEMP, 2679 M_WAITOK | M_ZERO); 2680 stack_zero(&tmp_data1->wlod_stack); 2681 stack_zero(&tmp_data2->wlod_stack); 2682 2683 restart: 2684 mtx_lock_spin(&w_mtx); 2685 generation = w_generation; 2686 mtx_unlock_spin(&w_mtx); 2687 sbuf_printf(sb, "Number of known direct relationships is %d\n", 2688 w_lohash.wloh_count); 2689 for (i = 1; i < w_max_used_index; i++) { 2690 mtx_lock_spin(&w_mtx); 2691 if (generation != w_generation) { 2692 mtx_unlock_spin(&w_mtx); 2693 2694 /* The graph has changed, try again. */ 2695 *oldidx = 0; 2696 sbuf_clear(sb); 2697 goto restart; 2698 } 2699 2700 w1 = &w_data[i]; 2701 if (w1->w_reversed == 0) { 2702 mtx_unlock_spin(&w_mtx); 2703 continue; 2704 } 2705 2706 /* Copy w1 locally so we can release the spin lock. */ 2707 *tmp_w1 = *w1; 2708 mtx_unlock_spin(&w_mtx); 2709 2710 if (tmp_w1->w_reversed == 0) 2711 continue; 2712 for (j = 1; j < w_max_used_index; j++) { 2713 if ((w_rmatrix[i][j] & WITNESS_REVERSAL) == 0 || i > j) 2714 continue; 2715 2716 mtx_lock_spin(&w_mtx); 2717 if (generation != w_generation) { 2718 mtx_unlock_spin(&w_mtx); 2719 2720 /* The graph has changed, try again. */ 2721 *oldidx = 0; 2722 sbuf_clear(sb); 2723 goto restart; 2724 } 2725 2726 w2 = &w_data[j]; 2727 data1 = witness_lock_order_get(w1, w2); 2728 data2 = witness_lock_order_get(w2, w1); 2729 2730 /* 2731 * Copy information locally so we can release the 2732 * spin lock. 2733 */ 2734 *tmp_w2 = *w2; 2735 2736 if (data1) { 2737 stack_zero(&tmp_data1->wlod_stack); 2738 stack_copy(&data1->wlod_stack, 2739 &tmp_data1->wlod_stack); 2740 } 2741 if (data2 && data2 != data1) { 2742 stack_zero(&tmp_data2->wlod_stack); 2743 stack_copy(&data2->wlod_stack, 2744 &tmp_data2->wlod_stack); 2745 } 2746 mtx_unlock_spin(&w_mtx); 2747 2748 if (blessed(tmp_w1, tmp_w2)) 2749 continue; 2750 2751 sbuf_printf(sb, 2752 "\nLock order reversal between \"%s\"(%s) and \"%s\"(%s)!\n", 2753 tmp_w1->w_name, tmp_w1->w_class->lc_name, 2754 tmp_w2->w_name, tmp_w2->w_class->lc_name); 2755 if (data1) { 2756 sbuf_printf(sb, 2757 "Lock order \"%s\"(%s) -> \"%s\"(%s) first seen at:\n", 2758 tmp_w1->w_name, tmp_w1->w_class->lc_name, 2759 tmp_w2->w_name, tmp_w2->w_class->lc_name); 2760 stack_sbuf_print(sb, &tmp_data1->wlod_stack); 2761 sbuf_putc(sb, '\n'); 2762 } 2763 if (data2 && data2 != data1) { 2764 sbuf_printf(sb, 2765 "Lock order \"%s\"(%s) -> \"%s\"(%s) first seen at:\n", 2766 tmp_w2->w_name, tmp_w2->w_class->lc_name, 2767 tmp_w1->w_name, tmp_w1->w_class->lc_name); 2768 stack_sbuf_print(sb, &tmp_data2->wlod_stack); 2769 sbuf_putc(sb, '\n'); 2770 } 2771 } 2772 } 2773 mtx_lock_spin(&w_mtx); 2774 if (generation != w_generation) { 2775 mtx_unlock_spin(&w_mtx); 2776 2777 /* 2778 * The graph changed while we were printing stack data, 2779 * try again. 2780 */ 2781 *oldidx = 0; 2782 sbuf_clear(sb); 2783 goto restart; 2784 } 2785 mtx_unlock_spin(&w_mtx); 2786 2787 /* Free temporary storage space. */ 2788 free(tmp_data1, M_TEMP); 2789 free(tmp_data2, M_TEMP); 2790 free(tmp_w1, M_TEMP); 2791 free(tmp_w2, M_TEMP); 2792 } 2793 2794 static int 2795 sysctl_debug_witness_badstacks(SYSCTL_HANDLER_ARGS) 2796 { 2797 struct sbuf *sb; 2798 int error; 2799 2800 if (witness_watch < 1) { 2801 error = SYSCTL_OUT(req, w_notrunning, sizeof(w_notrunning)); 2802 return (error); 2803 } 2804 if (witness_cold) { 2805 error = SYSCTL_OUT(req, w_stillcold, sizeof(w_stillcold)); 2806 return (error); 2807 } 2808 error = 0; 2809 sb = sbuf_new(NULL, NULL, badstack_sbuf_size, SBUF_AUTOEXTEND); 2810 if (sb == NULL) 2811 return (ENOMEM); 2812 2813 sbuf_print_witness_badstacks(sb, &req->oldidx); 2814 2815 sbuf_finish(sb); 2816 error = SYSCTL_OUT(req, sbuf_data(sb), sbuf_len(sb) + 1); 2817 sbuf_delete(sb); 2818 2819 return (error); 2820 } 2821 2822 #ifdef DDB 2823 static int 2824 sbuf_db_printf_drain(void *arg __unused, const char *data, int len) 2825 { 2826 2827 return (db_printf("%.*s", len, data)); 2828 } 2829 2830 DB_SHOW_COMMAND_FLAGS(badstacks, db_witness_badstacks, DB_CMD_MEMSAFE) 2831 { 2832 struct sbuf sb; 2833 char buffer[128]; 2834 size_t dummy; 2835 2836 sbuf_new(&sb, buffer, sizeof(buffer), SBUF_FIXEDLEN); 2837 sbuf_set_drain(&sb, sbuf_db_printf_drain, NULL); 2838 sbuf_print_witness_badstacks(&sb, &dummy); 2839 sbuf_finish(&sb); 2840 } 2841 #endif 2842 2843 static int 2844 sysctl_debug_witness_channel(SYSCTL_HANDLER_ARGS) 2845 { 2846 static const struct { 2847 enum witness_channel channel; 2848 const char *name; 2849 } channels[] = { 2850 { WITNESS_CONSOLE, "console" }, 2851 { WITNESS_LOG, "log" }, 2852 { WITNESS_NONE, "none" }, 2853 }; 2854 char buf[16]; 2855 u_int i; 2856 int error; 2857 2858 buf[0] = '\0'; 2859 for (i = 0; i < nitems(channels); i++) 2860 if (witness_channel == channels[i].channel) { 2861 snprintf(buf, sizeof(buf), "%s", channels[i].name); 2862 break; 2863 } 2864 2865 error = sysctl_handle_string(oidp, buf, sizeof(buf), req); 2866 if (error != 0 || req->newptr == NULL) 2867 return (error); 2868 2869 error = EINVAL; 2870 for (i = 0; i < nitems(channels); i++) 2871 if (strcmp(channels[i].name, buf) == 0) { 2872 witness_channel = channels[i].channel; 2873 error = 0; 2874 break; 2875 } 2876 return (error); 2877 } 2878 2879 static int 2880 sysctl_debug_witness_fullgraph(SYSCTL_HANDLER_ARGS) 2881 { 2882 struct witness *w; 2883 struct sbuf *sb; 2884 int error; 2885 2886 #ifdef __i386__ 2887 error = SYSCTL_OUT(req, w_notallowed, sizeof(w_notallowed)); 2888 return (error); 2889 #endif 2890 2891 if (witness_watch < 1) { 2892 error = SYSCTL_OUT(req, w_notrunning, sizeof(w_notrunning)); 2893 return (error); 2894 } 2895 if (witness_cold) { 2896 error = SYSCTL_OUT(req, w_stillcold, sizeof(w_stillcold)); 2897 return (error); 2898 } 2899 error = 0; 2900 2901 error = sysctl_wire_old_buffer(req, 0); 2902 if (error != 0) 2903 return (error); 2904 sb = sbuf_new_for_sysctl(NULL, NULL, FULLGRAPH_SBUF_SIZE, req); 2905 if (sb == NULL) 2906 return (ENOMEM); 2907 sbuf_putc(sb, '\n'); 2908 2909 mtx_lock_spin(&w_mtx); 2910 STAILQ_FOREACH(w, &w_all, w_list) 2911 w->w_displayed = 0; 2912 STAILQ_FOREACH(w, &w_all, w_list) 2913 witness_add_fullgraph(sb, w); 2914 mtx_unlock_spin(&w_mtx); 2915 2916 /* 2917 * Close the sbuf and return to userland. 2918 */ 2919 error = sbuf_finish(sb); 2920 sbuf_delete(sb); 2921 2922 return (error); 2923 } 2924 2925 static int 2926 sysctl_debug_witness_watch(SYSCTL_HANDLER_ARGS) 2927 { 2928 int error, value; 2929 2930 value = witness_watch; 2931 error = sysctl_handle_int(oidp, &value, 0, req); 2932 if (error != 0 || req->newptr == NULL) 2933 return (error); 2934 if (value > 1 || value < -1 || 2935 (witness_watch == -1 && value != witness_watch)) 2936 return (EINVAL); 2937 witness_watch = value; 2938 return (0); 2939 } 2940 2941 static void 2942 witness_add_fullgraph(struct sbuf *sb, struct witness *w) 2943 { 2944 int i; 2945 2946 if (w->w_displayed != 0 || (w->w_file == NULL && w->w_line == 0)) 2947 return; 2948 w->w_displayed = 1; 2949 2950 WITNESS_INDEX_ASSERT(w->w_index); 2951 for (i = 1; i <= w_max_used_index; i++) { 2952 if (w_rmatrix[w->w_index][i] & WITNESS_PARENT) { 2953 sbuf_printf(sb, "\"%s\",\"%s\"\n", w->w_name, 2954 w_data[i].w_name); 2955 witness_add_fullgraph(sb, &w_data[i]); 2956 } 2957 } 2958 } 2959 2960 /* 2961 * A simple hash function. Takes a key pointer and a key size. If size == 0, 2962 * interprets the key as a string and reads until the null 2963 * terminator. Otherwise, reads the first size bytes. Returns an unsigned 32-bit 2964 * hash value computed from the key. 2965 */ 2966 static uint32_t 2967 witness_hash_djb2(const uint8_t *key, uint32_t size) 2968 { 2969 unsigned int hash = 5381; 2970 int i; 2971 2972 /* hash = hash * 33 + key[i] */ 2973 if (size) 2974 for (i = 0; i < size; i++) 2975 hash = ((hash << 5) + hash) + (unsigned int)key[i]; 2976 else 2977 for (i = 0; key[i] != 0; i++) 2978 hash = ((hash << 5) + hash) + (unsigned int)key[i]; 2979 2980 return (hash); 2981 } 2982 2983 /* 2984 * Initializes the two witness hash tables. Called exactly once from 2985 * witness_initialize(). 2986 */ 2987 static void 2988 witness_init_hash_tables(void) 2989 { 2990 int i; 2991 2992 MPASS(witness_cold); 2993 2994 /* Initialize the hash tables. */ 2995 for (i = 0; i < WITNESS_HASH_SIZE; i++) 2996 w_hash.wh_array[i] = NULL; 2997 2998 w_hash.wh_size = WITNESS_HASH_SIZE; 2999 w_hash.wh_count = 0; 3000 3001 /* Initialize the lock order data hash. */ 3002 w_lofree = NULL; 3003 for (i = 0; i < WITNESS_LO_DATA_COUNT; i++) { 3004 memset(&w_lodata[i], 0, sizeof(w_lodata[i])); 3005 w_lodata[i].wlod_next = w_lofree; 3006 w_lofree = &w_lodata[i]; 3007 } 3008 w_lohash.wloh_size = WITNESS_LO_HASH_SIZE; 3009 w_lohash.wloh_count = 0; 3010 for (i = 0; i < WITNESS_LO_HASH_SIZE; i++) 3011 w_lohash.wloh_array[i] = NULL; 3012 } 3013 3014 static struct witness * 3015 witness_hash_get(const char *key) 3016 { 3017 struct witness *w; 3018 uint32_t hash; 3019 3020 MPASS(key != NULL); 3021 if (witness_cold == 0) 3022 mtx_assert(&w_mtx, MA_OWNED); 3023 hash = witness_hash_djb2(key, 0) % w_hash.wh_size; 3024 w = w_hash.wh_array[hash]; 3025 while (w != NULL) { 3026 if (strcmp(w->w_name, key) == 0) 3027 goto out; 3028 w = w->w_hash_next; 3029 } 3030 3031 out: 3032 return (w); 3033 } 3034 3035 static void 3036 witness_hash_put(struct witness *w) 3037 { 3038 uint32_t hash; 3039 3040 MPASS(w != NULL); 3041 MPASS(w->w_name != NULL); 3042 if (witness_cold == 0) 3043 mtx_assert(&w_mtx, MA_OWNED); 3044 KASSERT(witness_hash_get(w->w_name) == NULL, 3045 ("%s: trying to add a hash entry that already exists!", __func__)); 3046 KASSERT(w->w_hash_next == NULL, 3047 ("%s: w->w_hash_next != NULL", __func__)); 3048 3049 hash = witness_hash_djb2(w->w_name, 0) % w_hash.wh_size; 3050 w->w_hash_next = w_hash.wh_array[hash]; 3051 w_hash.wh_array[hash] = w; 3052 w_hash.wh_count++; 3053 } 3054 3055 static struct witness_lock_order_data * 3056 witness_lock_order_get(struct witness *parent, struct witness *child) 3057 { 3058 struct witness_lock_order_data *data = NULL; 3059 struct witness_lock_order_key key; 3060 unsigned int hash; 3061 3062 MPASS(parent != NULL && child != NULL); 3063 key.from = parent->w_index; 3064 key.to = child->w_index; 3065 WITNESS_INDEX_ASSERT(key.from); 3066 WITNESS_INDEX_ASSERT(key.to); 3067 if ((w_rmatrix[parent->w_index][child->w_index] 3068 & WITNESS_LOCK_ORDER_KNOWN) == 0) 3069 goto out; 3070 3071 hash = witness_hash_djb2((const char*)&key, 3072 sizeof(key)) % w_lohash.wloh_size; 3073 data = w_lohash.wloh_array[hash]; 3074 while (data != NULL) { 3075 if (witness_lock_order_key_equal(&data->wlod_key, &key)) 3076 break; 3077 data = data->wlod_next; 3078 } 3079 3080 out: 3081 return (data); 3082 } 3083 3084 /* 3085 * Verify that parent and child have a known relationship, are not the same, 3086 * and child is actually a child of parent. This is done without w_mtx 3087 * to avoid contention in the common case. 3088 */ 3089 static int 3090 witness_lock_order_check(struct witness *parent, struct witness *child) 3091 { 3092 3093 if (parent != child && 3094 w_rmatrix[parent->w_index][child->w_index] 3095 & WITNESS_LOCK_ORDER_KNOWN && 3096 isitmychild(parent, child)) 3097 return (1); 3098 3099 return (0); 3100 } 3101 3102 static int 3103 witness_lock_order_add(struct witness *parent, struct witness *child) 3104 { 3105 struct witness_lock_order_data *data = NULL; 3106 struct witness_lock_order_key key; 3107 unsigned int hash; 3108 3109 MPASS(parent != NULL && child != NULL); 3110 key.from = parent->w_index; 3111 key.to = child->w_index; 3112 WITNESS_INDEX_ASSERT(key.from); 3113 WITNESS_INDEX_ASSERT(key.to); 3114 if (w_rmatrix[parent->w_index][child->w_index] 3115 & WITNESS_LOCK_ORDER_KNOWN) 3116 return (1); 3117 3118 hash = witness_hash_djb2((const char*)&key, 3119 sizeof(key)) % w_lohash.wloh_size; 3120 w_rmatrix[parent->w_index][child->w_index] |= WITNESS_LOCK_ORDER_KNOWN; 3121 data = w_lofree; 3122 if (data == NULL) 3123 return (0); 3124 w_lofree = data->wlod_next; 3125 data->wlod_next = w_lohash.wloh_array[hash]; 3126 data->wlod_key = key; 3127 w_lohash.wloh_array[hash] = data; 3128 w_lohash.wloh_count++; 3129 stack_save(&data->wlod_stack); 3130 return (1); 3131 } 3132 3133 /* Call this whenever the structure of the witness graph changes. */ 3134 static void 3135 witness_increment_graph_generation(void) 3136 { 3137 3138 if (witness_cold == 0) 3139 mtx_assert(&w_mtx, MA_OWNED); 3140 w_generation++; 3141 } 3142 3143 static int 3144 witness_output_drain(void *arg __unused, const char *data, int len) 3145 { 3146 3147 witness_output("%.*s", len, data); 3148 return (len); 3149 } 3150 3151 static void 3152 witness_debugger(int cond, const char *msg) 3153 { 3154 char buf[32]; 3155 struct sbuf sb; 3156 struct stack st; 3157 3158 if (!cond) 3159 return; 3160 3161 if (witness_trace) { 3162 sbuf_new(&sb, buf, sizeof(buf), SBUF_FIXEDLEN); 3163 sbuf_set_drain(&sb, witness_output_drain, NULL); 3164 3165 stack_save(&st); 3166 witness_output("stack backtrace:\n"); 3167 stack_sbuf_print_ddb(&sb, &st); 3168 3169 sbuf_finish(&sb); 3170 } 3171 3172 witness_enter_debugger(msg); 3173 } 3174 3175 static void 3176 witness_enter_debugger(const char *msg) 3177 { 3178 #ifdef KDB 3179 if (witness_kdb) 3180 kdb_enter(KDB_WHY_WITNESS, msg); 3181 #endif 3182 } 3183