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/sysctl.h> 109 #include <sys/syslog.h> 110 #include <sys/systm.h> 111 112 #ifdef DDB 113 #include <ddb/ddb.h> 114 #endif 115 116 #include <machine/stdarg.h> 117 118 #if !defined(DDB) && !defined(STACK) 119 #error "DDB or STACK options are required for WITNESS" 120 #endif 121 122 /* Note that these traces do not work with KTR_ALQ. */ 123 #if 0 124 #define KTR_WITNESS KTR_SUBSYS 125 #else 126 #define KTR_WITNESS 0 127 #endif 128 129 #define LI_RECURSEMASK 0x0000ffff /* Recursion depth of lock instance. */ 130 #define LI_EXCLUSIVE 0x00010000 /* Exclusive lock instance. */ 131 #define LI_NORELEASE 0x00020000 /* Lock not allowed to be released. */ 132 #define LI_SLEEPABLE 0x00040000 /* Lock may be held while sleeping. */ 133 134 #ifndef WITNESS_COUNT 135 #define WITNESS_COUNT 1536 136 #endif 137 #define WITNESS_HASH_SIZE 251 /* Prime, gives load factor < 2 */ 138 #define WITNESS_PENDLIST (512 + (MAXCPU * 4)) 139 140 /* Allocate 256 KB of stack data space */ 141 #define WITNESS_LO_DATA_COUNT 2048 142 143 /* Prime, gives load factor of ~2 at full load */ 144 #define WITNESS_LO_HASH_SIZE 1021 145 146 /* 147 * XXX: This is somewhat bogus, as we assume here that at most 2048 threads 148 * will hold LOCK_NCHILDREN locks. We handle failure ok, and we should 149 * probably be safe for the most part, but it's still a SWAG. 150 */ 151 #define LOCK_NCHILDREN 5 152 #define LOCK_CHILDCOUNT 2048 153 154 #define MAX_W_NAME 64 155 156 #define FULLGRAPH_SBUF_SIZE 512 157 158 /* 159 * These flags go in the witness relationship matrix and describe the 160 * relationship between any two struct witness objects. 161 */ 162 #define WITNESS_UNRELATED 0x00 /* No lock order relation. */ 163 #define WITNESS_PARENT 0x01 /* Parent, aka direct ancestor. */ 164 #define WITNESS_ANCESTOR 0x02 /* Direct or indirect ancestor. */ 165 #define WITNESS_CHILD 0x04 /* Child, aka direct descendant. */ 166 #define WITNESS_DESCENDANT 0x08 /* Direct or indirect descendant. */ 167 #define WITNESS_ANCESTOR_MASK (WITNESS_PARENT | WITNESS_ANCESTOR) 168 #define WITNESS_DESCENDANT_MASK (WITNESS_CHILD | WITNESS_DESCENDANT) 169 #define WITNESS_RELATED_MASK \ 170 (WITNESS_ANCESTOR_MASK | WITNESS_DESCENDANT_MASK) 171 #define WITNESS_REVERSAL 0x10 /* A lock order reversal has been 172 * observed. */ 173 #define WITNESS_RESERVED1 0x20 /* Unused flag, reserved. */ 174 #define WITNESS_RESERVED2 0x40 /* Unused flag, reserved. */ 175 #define WITNESS_LOCK_ORDER_KNOWN 0x80 /* This lock order is known. */ 176 177 /* Descendant to ancestor flags */ 178 #define WITNESS_DTOA(x) (((x) & WITNESS_RELATED_MASK) >> 2) 179 180 /* Ancestor to descendant flags */ 181 #define WITNESS_ATOD(x) (((x) & WITNESS_RELATED_MASK) << 2) 182 183 #define WITNESS_INDEX_ASSERT(i) \ 184 MPASS((i) > 0 && (i) <= w_max_used_index && (i) < witness_count) 185 186 static MALLOC_DEFINE(M_WITNESS, "Witness", "Witness"); 187 188 /* 189 * Lock instances. A lock instance is the data associated with a lock while 190 * it is held by witness. For example, a lock instance will hold the 191 * recursion count of a lock. Lock instances are held in lists. Spin locks 192 * are held in a per-cpu list while sleep locks are held in per-thread list. 193 */ 194 struct lock_instance { 195 struct lock_object *li_lock; 196 const char *li_file; 197 int li_line; 198 u_int li_flags; 199 }; 200 201 /* 202 * A simple list type used to build the list of locks held by a thread 203 * or CPU. We can't simply embed the list in struct lock_object since a 204 * lock may be held by more than one thread if it is a shared lock. Locks 205 * are added to the head of the list, so we fill up each list entry from 206 * "the back" logically. To ease some of the arithmetic, we actually fill 207 * in each list entry the normal way (children[0] then children[1], etc.) but 208 * when we traverse the list we read children[count-1] as the first entry 209 * down to children[0] as the final entry. 210 */ 211 struct lock_list_entry { 212 struct lock_list_entry *ll_next; 213 struct lock_instance ll_children[LOCK_NCHILDREN]; 214 u_int ll_count; 215 }; 216 217 /* 218 * The main witness structure. One of these per named lock type in the system 219 * (for example, "vnode interlock"). 220 */ 221 struct witness { 222 char w_name[MAX_W_NAME]; 223 uint32_t w_index; /* Index in the relationship matrix */ 224 struct lock_class *w_class; 225 STAILQ_ENTRY(witness) w_list; /* List of all witnesses. */ 226 STAILQ_ENTRY(witness) w_typelist; /* Witnesses of a type. */ 227 struct witness *w_hash_next; /* Linked list in hash buckets. */ 228 const char *w_file; /* File where last acquired */ 229 uint32_t w_line; /* Line where last acquired */ 230 uint32_t w_refcount; 231 uint16_t w_num_ancestors; /* direct/indirect 232 * ancestor count */ 233 uint16_t w_num_descendants; /* direct/indirect 234 * descendant count */ 235 int16_t w_ddb_level; 236 unsigned w_displayed:1; 237 unsigned w_reversed:1; 238 }; 239 240 STAILQ_HEAD(witness_list, witness); 241 242 /* 243 * The witness hash table. Keys are witness names (const char *), elements are 244 * witness objects (struct witness *). 245 */ 246 struct witness_hash { 247 struct witness *wh_array[WITNESS_HASH_SIZE]; 248 uint32_t wh_size; 249 uint32_t wh_count; 250 }; 251 252 /* 253 * Key type for the lock order data hash table. 254 */ 255 struct witness_lock_order_key { 256 uint16_t from; 257 uint16_t to; 258 }; 259 260 struct witness_lock_order_data { 261 struct stack wlod_stack; 262 struct witness_lock_order_key wlod_key; 263 struct witness_lock_order_data *wlod_next; 264 }; 265 266 /* 267 * The witness lock order data hash table. Keys are witness index tuples 268 * (struct witness_lock_order_key), elements are lock order data objects 269 * (struct witness_lock_order_data). 270 */ 271 struct witness_lock_order_hash { 272 struct witness_lock_order_data *wloh_array[WITNESS_LO_HASH_SIZE]; 273 u_int wloh_size; 274 u_int wloh_count; 275 }; 276 277 struct witness_blessed { 278 const char *b_lock1; 279 const char *b_lock2; 280 }; 281 282 struct witness_pendhelp { 283 const char *wh_type; 284 struct lock_object *wh_lock; 285 }; 286 287 struct witness_order_list_entry { 288 const char *w_name; 289 struct lock_class *w_class; 290 }; 291 292 /* 293 * Returns 0 if one of the locks is a spin lock and the other is not. 294 * Returns 1 otherwise. 295 */ 296 static __inline int 297 witness_lock_type_equal(struct witness *w1, struct witness *w2) 298 { 299 300 return ((w1->w_class->lc_flags & (LC_SLEEPLOCK | LC_SPINLOCK)) == 301 (w2->w_class->lc_flags & (LC_SLEEPLOCK | LC_SPINLOCK))); 302 } 303 304 static __inline int 305 witness_lock_order_key_equal(const struct witness_lock_order_key *a, 306 const struct witness_lock_order_key *b) 307 { 308 309 return (a->from == b->from && a->to == b->to); 310 } 311 312 static int _isitmyx(struct witness *w1, struct witness *w2, int rmask, 313 const char *fname); 314 static void adopt(struct witness *parent, struct witness *child); 315 static int blessed(struct witness *, struct witness *); 316 static void depart(struct witness *w); 317 static struct witness *enroll(const char *description, 318 struct lock_class *lock_class); 319 static struct lock_instance *find_instance(struct lock_list_entry *list, 320 const struct lock_object *lock); 321 static int isitmychild(struct witness *parent, struct witness *child); 322 static int isitmydescendant(struct witness *parent, struct witness *child); 323 static void itismychild(struct witness *parent, struct witness *child); 324 static int sysctl_debug_witness_badstacks(SYSCTL_HANDLER_ARGS); 325 static int sysctl_debug_witness_watch(SYSCTL_HANDLER_ARGS); 326 static int sysctl_debug_witness_fullgraph(SYSCTL_HANDLER_ARGS); 327 static int sysctl_debug_witness_channel(SYSCTL_HANDLER_ARGS); 328 static void witness_add_fullgraph(struct sbuf *sb, struct witness *parent); 329 #ifdef DDB 330 static void witness_ddb_compute_levels(void); 331 static void witness_ddb_display(int(*)(const char *fmt, ...)); 332 static void witness_ddb_display_descendants(int(*)(const char *fmt, ...), 333 struct witness *, int indent); 334 static void witness_ddb_display_list(int(*prnt)(const char *fmt, ...), 335 struct witness_list *list); 336 static void witness_ddb_level_descendants(struct witness *parent, int l); 337 static void witness_ddb_list(struct thread *td); 338 #endif 339 static void witness_enter_debugger(const char *msg); 340 static void witness_debugger(int cond, const char *msg); 341 static void witness_free(struct witness *m); 342 static struct witness *witness_get(void); 343 static uint32_t witness_hash_djb2(const uint8_t *key, uint32_t size); 344 static struct witness *witness_hash_get(const char *key); 345 static void witness_hash_put(struct witness *w); 346 static void witness_init_hash_tables(void); 347 static void witness_increment_graph_generation(void); 348 static void witness_lock_list_free(struct lock_list_entry *lle); 349 static struct lock_list_entry *witness_lock_list_get(void); 350 static int witness_lock_order_add(struct witness *parent, 351 struct witness *child); 352 static int witness_lock_order_check(struct witness *parent, 353 struct witness *child); 354 static struct witness_lock_order_data *witness_lock_order_get( 355 struct witness *parent, 356 struct witness *child); 357 static void witness_list_lock(struct lock_instance *instance, 358 int (*prnt)(const char *fmt, ...)); 359 static int witness_output(const char *fmt, ...) __printflike(1, 2); 360 static int witness_output_drain(void *arg __unused, const char *data, 361 int len); 362 static int witness_voutput(const char *fmt, va_list ap) __printflike(1, 0); 363 static void witness_setflag(struct lock_object *lock, int flag, int set); 364 365 FEATURE(witness, "kernel has witness(9) support"); 366 367 static SYSCTL_NODE(_debug, OID_AUTO, witness, CTLFLAG_RW | CTLFLAG_MPSAFE, NULL, 368 "Witness Locking"); 369 370 /* 371 * If set to 0, lock order checking is disabled. If set to -1, 372 * witness is completely disabled. Otherwise witness performs full 373 * lock order checking for all locks. At runtime, lock order checking 374 * may be toggled. However, witness cannot be reenabled once it is 375 * completely disabled. 376 */ 377 static int witness_watch = 1; 378 SYSCTL_PROC(_debug_witness, OID_AUTO, watch, 379 CTLFLAG_RWTUN | CTLTYPE_INT | CTLFLAG_MPSAFE, NULL, 0, 380 sysctl_debug_witness_watch, "I", 381 "witness is watching lock operations"); 382 383 #ifdef KDB 384 /* 385 * When KDB is enabled and witness_kdb is 1, it will cause the system 386 * to drop into kdebug() when: 387 * - a lock hierarchy violation occurs 388 * - locks are held when going to sleep. 389 */ 390 #ifdef WITNESS_KDB 391 int witness_kdb = 1; 392 #else 393 int witness_kdb = 0; 394 #endif 395 SYSCTL_INT(_debug_witness, OID_AUTO, kdb, CTLFLAG_RWTUN, &witness_kdb, 0, ""); 396 #endif /* KDB */ 397 398 #if defined(DDB) || defined(KDB) 399 /* 400 * When DDB or KDB is enabled and witness_trace is 1, it will cause the system 401 * to print a stack trace: 402 * - a lock hierarchy violation occurs 403 * - locks are held when going to sleep. 404 */ 405 int witness_trace = 1; 406 SYSCTL_INT(_debug_witness, OID_AUTO, trace, CTLFLAG_RWTUN, &witness_trace, 0, ""); 407 #endif /* DDB || KDB */ 408 409 #ifdef WITNESS_SKIPSPIN 410 int witness_skipspin = 1; 411 #else 412 int witness_skipspin = 0; 413 #endif 414 SYSCTL_INT(_debug_witness, OID_AUTO, skipspin, CTLFLAG_RDTUN, &witness_skipspin, 0, ""); 415 416 int badstack_sbuf_size; 417 418 int witness_count = WITNESS_COUNT; 419 SYSCTL_INT(_debug_witness, OID_AUTO, witness_count, CTLFLAG_RDTUN, 420 &witness_count, 0, ""); 421 422 /* 423 * Output channel for witness messages. By default we print to the console. 424 */ 425 enum witness_channel { 426 WITNESS_CONSOLE, 427 WITNESS_LOG, 428 WITNESS_NONE, 429 }; 430 431 static enum witness_channel witness_channel = WITNESS_CONSOLE; 432 SYSCTL_PROC(_debug_witness, OID_AUTO, output_channel, 433 CTLTYPE_STRING | CTLFLAG_RWTUN | CTLFLAG_MPSAFE, NULL, 0, 434 sysctl_debug_witness_channel, "A", 435 "Output channel for warnings"); 436 437 /* 438 * Call this to print out the relations between locks. 439 */ 440 SYSCTL_PROC(_debug_witness, OID_AUTO, fullgraph, 441 CTLTYPE_STRING | CTLFLAG_RD | CTLFLAG_MPSAFE, NULL, 0, 442 sysctl_debug_witness_fullgraph, "A", 443 "Show locks relation graphs"); 444 445 /* 446 * Call this to print out the witness faulty stacks. 447 */ 448 SYSCTL_PROC(_debug_witness, OID_AUTO, badstacks, 449 CTLTYPE_STRING | CTLFLAG_RD | CTLFLAG_MPSAFE, NULL, 0, 450 sysctl_debug_witness_badstacks, "A", 451 "Show bad witness stacks"); 452 453 static struct mtx w_mtx; 454 455 /* w_list */ 456 static struct witness_list w_free = STAILQ_HEAD_INITIALIZER(w_free); 457 static struct witness_list w_all = STAILQ_HEAD_INITIALIZER(w_all); 458 459 /* w_typelist */ 460 static struct witness_list w_spin = STAILQ_HEAD_INITIALIZER(w_spin); 461 static struct witness_list w_sleep = STAILQ_HEAD_INITIALIZER(w_sleep); 462 463 /* lock list */ 464 static struct lock_list_entry *w_lock_list_free = NULL; 465 static struct witness_pendhelp pending_locks[WITNESS_PENDLIST]; 466 static u_int pending_cnt; 467 468 static int w_free_cnt, w_spin_cnt, w_sleep_cnt; 469 SYSCTL_INT(_debug_witness, OID_AUTO, free_cnt, CTLFLAG_RD, &w_free_cnt, 0, ""); 470 SYSCTL_INT(_debug_witness, OID_AUTO, spin_cnt, CTLFLAG_RD, &w_spin_cnt, 0, ""); 471 SYSCTL_INT(_debug_witness, OID_AUTO, sleep_cnt, CTLFLAG_RD, &w_sleep_cnt, 0, 472 ""); 473 474 static struct witness *w_data; 475 static uint8_t **w_rmatrix; 476 static struct lock_list_entry w_locklistdata[LOCK_CHILDCOUNT]; 477 static struct witness_hash w_hash; /* The witness hash table. */ 478 479 /* The lock order data hash */ 480 static struct witness_lock_order_data w_lodata[WITNESS_LO_DATA_COUNT]; 481 static struct witness_lock_order_data *w_lofree = NULL; 482 static struct witness_lock_order_hash w_lohash; 483 static int w_max_used_index = 0; 484 static unsigned int w_generation = 0; 485 static const char w_notrunning[] = "Witness not running\n"; 486 static const char w_stillcold[] = "Witness is still cold\n"; 487 #ifdef __i386__ 488 static const char w_notallowed[] = "The sysctl is disabled on the arch\n"; 489 #endif 490 491 static struct witness_order_list_entry order_lists[] = { 492 /* 493 * sx locks 494 */ 495 { "proctree", &lock_class_sx }, 496 { "allproc", &lock_class_sx }, 497 { "allprison", &lock_class_sx }, 498 { NULL, NULL }, 499 /* 500 * Various mutexes 501 */ 502 { "Giant", &lock_class_mtx_sleep }, 503 { "pipe mutex", &lock_class_mtx_sleep }, 504 { "sigio lock", &lock_class_mtx_sleep }, 505 { "process group", &lock_class_mtx_sleep }, 506 #ifdef HWPMC_HOOKS 507 { "pmc-sleep", &lock_class_mtx_sleep }, 508 #endif 509 { "process lock", &lock_class_mtx_sleep }, 510 { "session", &lock_class_mtx_sleep }, 511 { "uidinfo hash", &lock_class_rw }, 512 { "time lock", &lock_class_mtx_sleep }, 513 { NULL, NULL }, 514 /* 515 * umtx 516 */ 517 { "umtx lock", &lock_class_mtx_sleep }, 518 { NULL, NULL }, 519 /* 520 * Sockets 521 */ 522 { "accept", &lock_class_mtx_sleep }, 523 { "so_snd", &lock_class_mtx_sleep }, 524 { "so_rcv", &lock_class_mtx_sleep }, 525 { "sellck", &lock_class_mtx_sleep }, 526 { NULL, NULL }, 527 /* 528 * Routing 529 */ 530 { "so_rcv", &lock_class_mtx_sleep }, 531 { "radix node head", &lock_class_rm }, 532 { "ifaddr", &lock_class_mtx_sleep }, 533 { NULL, NULL }, 534 /* 535 * IPv4 multicast: 536 * protocol locks before interface locks, after UDP locks. 537 */ 538 { "in_multi_sx", &lock_class_sx }, 539 { "udpinp", &lock_class_rw }, 540 { "in_multi_list_mtx", &lock_class_mtx_sleep }, 541 { "igmp_mtx", &lock_class_mtx_sleep }, 542 { "if_addr_lock", &lock_class_mtx_sleep }, 543 { NULL, NULL }, 544 /* 545 * IPv6 multicast: 546 * protocol locks before interface locks, after UDP locks. 547 */ 548 { "in6_multi_sx", &lock_class_sx }, 549 { "udpinp", &lock_class_rw }, 550 { "in6_multi_list_mtx", &lock_class_mtx_sleep }, 551 { "mld_mtx", &lock_class_mtx_sleep }, 552 { "if_addr_lock", &lock_class_mtx_sleep }, 553 { NULL, NULL }, 554 /* 555 * UNIX Domain Sockets 556 */ 557 { "unp_link_rwlock", &lock_class_rw }, 558 { "unp_list_lock", &lock_class_mtx_sleep }, 559 { "unp", &lock_class_mtx_sleep }, 560 { "so_snd", &lock_class_mtx_sleep }, 561 { NULL, NULL }, 562 /* 563 * UDP/IP 564 */ 565 { "udpinp", &lock_class_rw }, 566 { "udp", &lock_class_mtx_sleep }, 567 { "so_snd", &lock_class_mtx_sleep }, 568 { NULL, NULL }, 569 /* 570 * TCP/IP 571 */ 572 { "tcpinp", &lock_class_rw }, 573 { "tcp", &lock_class_mtx_sleep }, 574 { "so_snd", &lock_class_mtx_sleep }, 575 { NULL, NULL }, 576 /* 577 * BPF 578 */ 579 { "bpf global lock", &lock_class_sx }, 580 { "bpf cdev lock", &lock_class_mtx_sleep }, 581 { NULL, NULL }, 582 /* 583 * NFS server 584 */ 585 { "nfsd_mtx", &lock_class_mtx_sleep }, 586 { "so_snd", &lock_class_mtx_sleep }, 587 { NULL, NULL }, 588 589 /* 590 * IEEE 802.11 591 */ 592 { "802.11 com lock", &lock_class_mtx_sleep}, 593 { NULL, NULL }, 594 /* 595 * Network drivers 596 */ 597 { "network driver", &lock_class_mtx_sleep}, 598 { NULL, NULL }, 599 600 /* 601 * Netgraph 602 */ 603 { "ng_node", &lock_class_mtx_sleep }, 604 { "ng_worklist", &lock_class_mtx_sleep }, 605 { NULL, NULL }, 606 /* 607 * CDEV 608 */ 609 { "vm map (system)", &lock_class_mtx_sleep }, 610 { "vnode interlock", &lock_class_mtx_sleep }, 611 { "cdev", &lock_class_mtx_sleep }, 612 { "devthrd", &lock_class_mtx_sleep }, 613 { NULL, NULL }, 614 /* 615 * VM 616 */ 617 { "vm map (user)", &lock_class_sx }, 618 { "vm object", &lock_class_rw }, 619 { "vm page", &lock_class_mtx_sleep }, 620 { "pmap pv global", &lock_class_rw }, 621 { "pmap", &lock_class_mtx_sleep }, 622 { "pmap pv list", &lock_class_rw }, 623 { "vm page free queue", &lock_class_mtx_sleep }, 624 { "vm pagequeue", &lock_class_mtx_sleep }, 625 { NULL, NULL }, 626 /* 627 * kqueue/VFS interaction 628 */ 629 { "kqueue", &lock_class_mtx_sleep }, 630 { "struct mount mtx", &lock_class_mtx_sleep }, 631 { "vnode interlock", &lock_class_mtx_sleep }, 632 { NULL, NULL }, 633 /* 634 * VFS namecache 635 */ 636 { "ncvn", &lock_class_mtx_sleep }, 637 { "ncbuc", &lock_class_mtx_sleep }, 638 { "vnode interlock", &lock_class_mtx_sleep }, 639 { "ncneg", &lock_class_mtx_sleep }, 640 { NULL, NULL }, 641 /* 642 * ZFS locking 643 */ 644 { "dn->dn_mtx", &lock_class_sx }, 645 { "dr->dt.di.dr_mtx", &lock_class_sx }, 646 { "db->db_mtx", &lock_class_sx }, 647 { NULL, NULL }, 648 /* 649 * TCP log locks 650 */ 651 { "TCP ID tree", &lock_class_rw }, 652 { "tcp log id bucket", &lock_class_mtx_sleep }, 653 { "tcpinp", &lock_class_rw }, 654 { "TCP log expireq", &lock_class_mtx_sleep }, 655 { NULL, NULL }, 656 /* 657 * spin locks 658 */ 659 #ifdef SMP 660 { "ap boot", &lock_class_mtx_spin }, 661 #endif 662 { "rm.mutex_mtx", &lock_class_mtx_spin }, 663 #ifdef __i386__ 664 { "cy", &lock_class_mtx_spin }, 665 #endif 666 { "scc_hwmtx", &lock_class_mtx_spin }, 667 { "uart_hwmtx", &lock_class_mtx_spin }, 668 { "fast_taskqueue", &lock_class_mtx_spin }, 669 { "intr table", &lock_class_mtx_spin }, 670 { "process slock", &lock_class_mtx_spin }, 671 { "syscons video lock", &lock_class_mtx_spin }, 672 { "sleepq chain", &lock_class_mtx_spin }, 673 { "rm_spinlock", &lock_class_mtx_spin }, 674 { "turnstile chain", &lock_class_mtx_spin }, 675 { "turnstile lock", &lock_class_mtx_spin }, 676 { "sched lock", &lock_class_mtx_spin }, 677 { "td_contested", &lock_class_mtx_spin }, 678 { "callout", &lock_class_mtx_spin }, 679 { "entropy harvest mutex", &lock_class_mtx_spin }, 680 #ifdef SMP 681 { "smp rendezvous", &lock_class_mtx_spin }, 682 #endif 683 #ifdef __powerpc__ 684 { "tlb0", &lock_class_mtx_spin }, 685 #endif 686 { NULL, NULL }, 687 { "sched lock", &lock_class_mtx_spin }, 688 #ifdef HWPMC_HOOKS 689 { "pmc-per-proc", &lock_class_mtx_spin }, 690 #endif 691 { NULL, NULL }, 692 /* 693 * leaf locks 694 */ 695 { "intrcnt", &lock_class_mtx_spin }, 696 { "icu", &lock_class_mtx_spin }, 697 #ifdef __i386__ 698 { "allpmaps", &lock_class_mtx_spin }, 699 { "descriptor tables", &lock_class_mtx_spin }, 700 #endif 701 { "clk", &lock_class_mtx_spin }, 702 { "cpuset", &lock_class_mtx_spin }, 703 { "mprof lock", &lock_class_mtx_spin }, 704 { "zombie lock", &lock_class_mtx_spin }, 705 { "ALD Queue", &lock_class_mtx_spin }, 706 #if defined(__i386__) || defined(__amd64__) 707 { "pcicfg", &lock_class_mtx_spin }, 708 { "NDIS thread lock", &lock_class_mtx_spin }, 709 #endif 710 { "tw_osl_io_lock", &lock_class_mtx_spin }, 711 { "tw_osl_q_lock", &lock_class_mtx_spin }, 712 { "tw_cl_io_lock", &lock_class_mtx_spin }, 713 { "tw_cl_intr_lock", &lock_class_mtx_spin }, 714 { "tw_cl_gen_lock", &lock_class_mtx_spin }, 715 #ifdef HWPMC_HOOKS 716 { "pmc-leaf", &lock_class_mtx_spin }, 717 #endif 718 { "blocked lock", &lock_class_mtx_spin }, 719 { NULL, NULL }, 720 { NULL, NULL } 721 }; 722 723 /* 724 * Pairs of locks which have been blessed. Witness does not complain about 725 * order problems with blessed lock pairs. Please do not add an entry to the 726 * table without an explanatory comment. 727 */ 728 static struct witness_blessed blessed_list[] = { 729 /* 730 * See the comment in ufs_dirhash.c. Basically, a vnode lock serializes 731 * both lock orders, so a deadlock cannot happen as a result of this 732 * LOR. 733 */ 734 { "dirhash", "bufwait" }, 735 736 /* 737 * A UFS vnode may be locked in vget() while a buffer belonging to the 738 * parent directory vnode is locked. 739 */ 740 { "ufs", "bufwait" }, 741 742 /* 743 * The tarfs decompression stream vnode may be locked while a 744 * buffer belonging to a tarfs data vnode is locked. 745 */ 746 { "tarfs", "bufwait" }, 747 }; 748 749 /* 750 * This global is set to 0 once it becomes safe to use the witness code. 751 */ 752 static int witness_cold = 1; 753 754 /* 755 * This global is set to 1 once the static lock orders have been enrolled 756 * so that a warning can be issued for any spin locks enrolled later. 757 */ 758 static int witness_spin_warn = 0; 759 760 /* Trim useless garbage from filenames. */ 761 static const char * 762 fixup_filename(const char *file) 763 { 764 765 if (file == NULL) 766 return (NULL); 767 while (strncmp(file, "../", 3) == 0) 768 file += 3; 769 return (file); 770 } 771 772 /* 773 * Calculate the size of early witness structures. 774 */ 775 int 776 witness_startup_count(void) 777 { 778 int sz; 779 780 sz = sizeof(struct witness) * witness_count; 781 sz += sizeof(*w_rmatrix) * (witness_count + 1); 782 sz += sizeof(*w_rmatrix[0]) * (witness_count + 1) * 783 (witness_count + 1); 784 785 return (sz); 786 } 787 788 /* 789 * The WITNESS-enabled diagnostic code. Note that the witness code does 790 * assume that the early boot is single-threaded at least until after this 791 * routine is completed. 792 */ 793 void 794 witness_startup(void *mem) 795 { 796 struct lock_object *lock; 797 struct witness_order_list_entry *order; 798 struct witness *w, *w1; 799 uintptr_t p; 800 int i; 801 802 p = (uintptr_t)mem; 803 w_data = (void *)p; 804 p += sizeof(struct witness) * witness_count; 805 806 w_rmatrix = (void *)p; 807 p += sizeof(*w_rmatrix) * (witness_count + 1); 808 809 for (i = 0; i < witness_count + 1; i++) { 810 w_rmatrix[i] = (void *)p; 811 p += sizeof(*w_rmatrix[i]) * (witness_count + 1); 812 } 813 badstack_sbuf_size = witness_count * 256; 814 815 /* 816 * We have to release Giant before initializing its witness 817 * structure so that WITNESS doesn't get confused. 818 */ 819 mtx_unlock(&Giant); 820 mtx_assert(&Giant, MA_NOTOWNED); 821 822 CTR1(KTR_WITNESS, "%s: initializing witness", __func__); 823 mtx_init(&w_mtx, "witness lock", NULL, MTX_SPIN | MTX_QUIET | 824 MTX_NOWITNESS | MTX_NOPROFILE); 825 for (i = witness_count - 1; i >= 0; i--) { 826 w = &w_data[i]; 827 memset(w, 0, sizeof(*w)); 828 w_data[i].w_index = i; /* Witness index never changes. */ 829 witness_free(w); 830 } 831 KASSERT(STAILQ_FIRST(&w_free)->w_index == 0, 832 ("%s: Invalid list of free witness objects", __func__)); 833 834 /* Witness with index 0 is not used to aid in debugging. */ 835 STAILQ_REMOVE_HEAD(&w_free, w_list); 836 w_free_cnt--; 837 838 for (i = 0; i < witness_count; i++) { 839 memset(w_rmatrix[i], 0, sizeof(*w_rmatrix[i]) * 840 (witness_count + 1)); 841 } 842 843 for (i = 0; i < LOCK_CHILDCOUNT; i++) 844 witness_lock_list_free(&w_locklistdata[i]); 845 witness_init_hash_tables(); 846 847 /* First add in all the specified order lists. */ 848 for (order = order_lists; order->w_name != NULL; order++) { 849 w = enroll(order->w_name, order->w_class); 850 if (w == NULL) 851 continue; 852 w->w_file = "order list"; 853 for (order++; order->w_name != NULL; order++) { 854 w1 = enroll(order->w_name, order->w_class); 855 if (w1 == NULL) 856 continue; 857 w1->w_file = "order list"; 858 itismychild(w, w1); 859 w = w1; 860 } 861 } 862 witness_spin_warn = 1; 863 864 /* Iterate through all locks and add them to witness. */ 865 for (i = 0; pending_locks[i].wh_lock != NULL; i++) { 866 lock = pending_locks[i].wh_lock; 867 KASSERT(lock->lo_flags & LO_WITNESS, 868 ("%s: lock %s is on pending list but not LO_WITNESS", 869 __func__, lock->lo_name)); 870 lock->lo_witness = enroll(pending_locks[i].wh_type, 871 LOCK_CLASS(lock)); 872 } 873 874 /* Mark the witness code as being ready for use. */ 875 witness_cold = 0; 876 877 mtx_lock(&Giant); 878 } 879 880 void 881 witness_init(struct lock_object *lock, const char *type) 882 { 883 struct lock_class *class; 884 885 /* Various sanity checks. */ 886 class = LOCK_CLASS(lock); 887 if ((lock->lo_flags & LO_RECURSABLE) != 0 && 888 (class->lc_flags & LC_RECURSABLE) == 0) 889 kassert_panic("%s: lock (%s) %s can not be recursable", 890 __func__, class->lc_name, lock->lo_name); 891 if ((lock->lo_flags & LO_SLEEPABLE) != 0 && 892 (class->lc_flags & LC_SLEEPABLE) == 0) 893 kassert_panic("%s: lock (%s) %s can not be sleepable", 894 __func__, class->lc_name, lock->lo_name); 895 if ((lock->lo_flags & LO_UPGRADABLE) != 0 && 896 (class->lc_flags & LC_UPGRADABLE) == 0) 897 kassert_panic("%s: lock (%s) %s can not be upgradable", 898 __func__, class->lc_name, lock->lo_name); 899 900 /* 901 * If we shouldn't watch this lock, then just clear lo_witness. 902 * Otherwise, if witness_cold is set, then it is too early to 903 * enroll this lock, so defer it to witness_initialize() by adding 904 * it to the pending_locks list. If it is not too early, then enroll 905 * the lock now. 906 */ 907 if (witness_watch < 1 || KERNEL_PANICKED() || 908 (lock->lo_flags & LO_WITNESS) == 0) 909 lock->lo_witness = NULL; 910 else if (witness_cold) { 911 pending_locks[pending_cnt].wh_lock = lock; 912 pending_locks[pending_cnt++].wh_type = type; 913 if (pending_cnt > WITNESS_PENDLIST) 914 panic("%s: pending locks list is too small, " 915 "increase WITNESS_PENDLIST\n", 916 __func__); 917 } else 918 lock->lo_witness = enroll(type, class); 919 } 920 921 void 922 witness_destroy(struct lock_object *lock) 923 { 924 struct lock_class *class; 925 struct witness *w; 926 927 class = LOCK_CLASS(lock); 928 929 if (witness_cold) 930 panic("lock (%s) %s destroyed while witness_cold", 931 class->lc_name, lock->lo_name); 932 933 /* XXX: need to verify that no one holds the lock */ 934 if ((lock->lo_flags & LO_WITNESS) == 0 || lock->lo_witness == NULL) 935 return; 936 w = lock->lo_witness; 937 938 mtx_lock_spin(&w_mtx); 939 MPASS(w->w_refcount > 0); 940 w->w_refcount--; 941 942 if (w->w_refcount == 0) 943 depart(w); 944 mtx_unlock_spin(&w_mtx); 945 } 946 947 #ifdef DDB 948 static void 949 witness_ddb_compute_levels(void) 950 { 951 struct witness *w; 952 953 /* 954 * First clear all levels. 955 */ 956 STAILQ_FOREACH(w, &w_all, w_list) 957 w->w_ddb_level = -1; 958 959 /* 960 * Look for locks with no parents and level all their descendants. 961 */ 962 STAILQ_FOREACH(w, &w_all, w_list) { 963 /* If the witness has ancestors (is not a root), skip it. */ 964 if (w->w_num_ancestors > 0) 965 continue; 966 witness_ddb_level_descendants(w, 0); 967 } 968 } 969 970 static void 971 witness_ddb_level_descendants(struct witness *w, int l) 972 { 973 int i; 974 975 if (w->w_ddb_level >= l) 976 return; 977 978 w->w_ddb_level = l; 979 l++; 980 981 for (i = 1; i <= w_max_used_index; i++) { 982 if (w_rmatrix[w->w_index][i] & WITNESS_PARENT) 983 witness_ddb_level_descendants(&w_data[i], l); 984 } 985 } 986 987 static void 988 witness_ddb_display_descendants(int(*prnt)(const char *fmt, ...), 989 struct witness *w, int indent) 990 { 991 int i; 992 993 for (i = 0; i < indent; i++) 994 prnt(" "); 995 prnt("%s (type: %s, depth: %d, active refs: %d)", 996 w->w_name, w->w_class->lc_name, 997 w->w_ddb_level, w->w_refcount); 998 if (w->w_displayed) { 999 prnt(" -- (already displayed)\n"); 1000 return; 1001 } 1002 w->w_displayed = 1; 1003 if (w->w_file != NULL && w->w_line != 0) 1004 prnt(" -- last acquired @ %s:%d\n", fixup_filename(w->w_file), 1005 w->w_line); 1006 else 1007 prnt(" -- never acquired\n"); 1008 indent++; 1009 WITNESS_INDEX_ASSERT(w->w_index); 1010 for (i = 1; i <= w_max_used_index; i++) { 1011 if (db_pager_quit) 1012 return; 1013 if (w_rmatrix[w->w_index][i] & WITNESS_PARENT) 1014 witness_ddb_display_descendants(prnt, &w_data[i], 1015 indent); 1016 } 1017 } 1018 1019 static void 1020 witness_ddb_display_list(int(*prnt)(const char *fmt, ...), 1021 struct witness_list *list) 1022 { 1023 struct witness *w; 1024 1025 STAILQ_FOREACH(w, list, w_typelist) { 1026 if (w->w_file == NULL || w->w_ddb_level > 0) 1027 continue; 1028 1029 /* This lock has no anscestors - display its descendants. */ 1030 witness_ddb_display_descendants(prnt, w, 0); 1031 if (db_pager_quit) 1032 return; 1033 } 1034 } 1035 1036 static void 1037 witness_ddb_display(int(*prnt)(const char *fmt, ...)) 1038 { 1039 struct witness *w; 1040 1041 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); 1042 witness_ddb_compute_levels(); 1043 1044 /* Clear all the displayed flags. */ 1045 STAILQ_FOREACH(w, &w_all, w_list) 1046 w->w_displayed = 0; 1047 1048 /* 1049 * First, handle sleep locks which have been acquired at least 1050 * once. 1051 */ 1052 prnt("Sleep locks:\n"); 1053 witness_ddb_display_list(prnt, &w_sleep); 1054 if (db_pager_quit) 1055 return; 1056 1057 /* 1058 * Now do spin locks which have been acquired at least once. 1059 */ 1060 prnt("\nSpin locks:\n"); 1061 witness_ddb_display_list(prnt, &w_spin); 1062 if (db_pager_quit) 1063 return; 1064 1065 /* 1066 * Finally, any locks which have not been acquired yet. 1067 */ 1068 prnt("\nLocks which were never acquired:\n"); 1069 STAILQ_FOREACH(w, &w_all, w_list) { 1070 if (w->w_file != NULL || w->w_refcount == 0) 1071 continue; 1072 prnt("%s (type: %s, depth: %d)\n", w->w_name, 1073 w->w_class->lc_name, w->w_ddb_level); 1074 if (db_pager_quit) 1075 return; 1076 } 1077 } 1078 #endif /* DDB */ 1079 1080 int 1081 witness_defineorder(struct lock_object *lock1, struct lock_object *lock2) 1082 { 1083 1084 if (witness_watch == -1 || KERNEL_PANICKED()) 1085 return (0); 1086 1087 /* Require locks that witness knows about. */ 1088 if (lock1 == NULL || lock1->lo_witness == NULL || lock2 == NULL || 1089 lock2->lo_witness == NULL) 1090 return (EINVAL); 1091 1092 mtx_assert(&w_mtx, MA_NOTOWNED); 1093 mtx_lock_spin(&w_mtx); 1094 1095 /* 1096 * If we already have either an explicit or implied lock order that 1097 * is the other way around, then return an error. 1098 */ 1099 if (witness_watch && 1100 isitmydescendant(lock2->lo_witness, lock1->lo_witness)) { 1101 mtx_unlock_spin(&w_mtx); 1102 return (EDOOFUS); 1103 } 1104 1105 /* Try to add the new order. */ 1106 CTR3(KTR_WITNESS, "%s: adding %s as a child of %s", __func__, 1107 lock2->lo_witness->w_name, lock1->lo_witness->w_name); 1108 itismychild(lock1->lo_witness, lock2->lo_witness); 1109 mtx_unlock_spin(&w_mtx); 1110 return (0); 1111 } 1112 1113 void 1114 witness_checkorder(struct lock_object *lock, int flags, const char *file, 1115 int line, struct lock_object *interlock) 1116 { 1117 struct lock_list_entry *lock_list, *lle; 1118 struct lock_instance *lock1, *lock2, *plock; 1119 struct lock_class *class, *iclass; 1120 struct witness *w, *w1; 1121 struct thread *td; 1122 int i, j; 1123 1124 if (witness_cold || witness_watch < 1 || lock->lo_witness == NULL || 1125 KERNEL_PANICKED()) 1126 return; 1127 1128 w = lock->lo_witness; 1129 class = LOCK_CLASS(lock); 1130 td = curthread; 1131 1132 if (class->lc_flags & LC_SLEEPLOCK) { 1133 /* 1134 * Since spin locks include a critical section, this check 1135 * implicitly enforces a lock order of all sleep locks before 1136 * all spin locks. 1137 */ 1138 if (td->td_critnest != 0 && !kdb_active) 1139 kassert_panic("acquiring blockable sleep lock with " 1140 "spinlock or critical section held (%s) %s @ %s:%d", 1141 class->lc_name, lock->lo_name, 1142 fixup_filename(file), line); 1143 1144 /* 1145 * If this is the first lock acquired then just return as 1146 * no order checking is needed. 1147 */ 1148 lock_list = td->td_sleeplocks; 1149 if (lock_list == NULL || lock_list->ll_count == 0) 1150 return; 1151 } else { 1152 /* 1153 * If this is the first lock, just return as no order 1154 * checking is needed. Avoid problems with thread 1155 * migration pinning the thread while checking if 1156 * spinlocks are held. If at least one spinlock is held 1157 * the thread is in a safe path and it is allowed to 1158 * unpin it. 1159 */ 1160 sched_pin(); 1161 lock_list = PCPU_GET(spinlocks); 1162 if (lock_list == NULL || lock_list->ll_count == 0) { 1163 sched_unpin(); 1164 return; 1165 } 1166 sched_unpin(); 1167 } 1168 1169 /* 1170 * Check to see if we are recursing on a lock we already own. If 1171 * so, make sure that we don't mismatch exclusive and shared lock 1172 * acquires. 1173 */ 1174 lock1 = find_instance(lock_list, lock); 1175 if (lock1 != NULL) { 1176 if ((lock1->li_flags & LI_EXCLUSIVE) != 0 && 1177 (flags & LOP_EXCLUSIVE) == 0) { 1178 witness_output("shared lock of (%s) %s @ %s:%d\n", 1179 class->lc_name, lock->lo_name, 1180 fixup_filename(file), line); 1181 witness_output("while exclusively locked from %s:%d\n", 1182 fixup_filename(lock1->li_file), lock1->li_line); 1183 kassert_panic("excl->share"); 1184 } 1185 if ((lock1->li_flags & LI_EXCLUSIVE) == 0 && 1186 (flags & LOP_EXCLUSIVE) != 0) { 1187 witness_output("exclusive lock of (%s) %s @ %s:%d\n", 1188 class->lc_name, lock->lo_name, 1189 fixup_filename(file), line); 1190 witness_output("while share locked from %s:%d\n", 1191 fixup_filename(lock1->li_file), lock1->li_line); 1192 kassert_panic("share->excl"); 1193 } 1194 return; 1195 } 1196 1197 /* Warn if the interlock is not locked exactly once. */ 1198 if (interlock != NULL) { 1199 iclass = LOCK_CLASS(interlock); 1200 lock1 = find_instance(lock_list, interlock); 1201 if (lock1 == NULL) 1202 kassert_panic("interlock (%s) %s not locked @ %s:%d", 1203 iclass->lc_name, interlock->lo_name, 1204 fixup_filename(file), line); 1205 else if ((lock1->li_flags & LI_RECURSEMASK) != 0) 1206 kassert_panic("interlock (%s) %s recursed @ %s:%d", 1207 iclass->lc_name, interlock->lo_name, 1208 fixup_filename(file), line); 1209 } 1210 1211 /* 1212 * Find the previously acquired lock, but ignore interlocks. 1213 */ 1214 plock = &lock_list->ll_children[lock_list->ll_count - 1]; 1215 if (interlock != NULL && plock->li_lock == interlock) { 1216 if (lock_list->ll_count > 1) 1217 plock = 1218 &lock_list->ll_children[lock_list->ll_count - 2]; 1219 else { 1220 lle = lock_list->ll_next; 1221 1222 /* 1223 * The interlock is the only lock we hold, so 1224 * simply return. 1225 */ 1226 if (lle == NULL) 1227 return; 1228 plock = &lle->ll_children[lle->ll_count - 1]; 1229 } 1230 } 1231 1232 /* 1233 * Try to perform most checks without a lock. If this succeeds we 1234 * can skip acquiring the lock and return success. Otherwise we redo 1235 * the check with the lock held to handle races with concurrent updates. 1236 */ 1237 w1 = plock->li_lock->lo_witness; 1238 if (witness_lock_order_check(w1, w)) 1239 return; 1240 1241 mtx_lock_spin(&w_mtx); 1242 if (witness_lock_order_check(w1, w)) { 1243 mtx_unlock_spin(&w_mtx); 1244 return; 1245 } 1246 witness_lock_order_add(w1, w); 1247 1248 /* 1249 * Check for duplicate locks of the same type. Note that we only 1250 * have to check for this on the last lock we just acquired. Any 1251 * other cases will be caught as lock order violations. 1252 */ 1253 if (w1 == w) { 1254 i = w->w_index; 1255 if (!(lock->lo_flags & LO_DUPOK) && !(flags & LOP_DUPOK) && 1256 !(w_rmatrix[i][i] & WITNESS_REVERSAL)) { 1257 w_rmatrix[i][i] |= WITNESS_REVERSAL; 1258 w->w_reversed = 1; 1259 mtx_unlock_spin(&w_mtx); 1260 witness_output( 1261 "acquiring duplicate lock of same type: \"%s\"\n", 1262 w->w_name); 1263 witness_output(" 1st %s @ %s:%d\n", plock->li_lock->lo_name, 1264 fixup_filename(plock->li_file), plock->li_line); 1265 witness_output(" 2nd %s @ %s:%d\n", lock->lo_name, 1266 fixup_filename(file), line); 1267 witness_debugger(1, __func__); 1268 } else 1269 mtx_unlock_spin(&w_mtx); 1270 return; 1271 } 1272 mtx_assert(&w_mtx, MA_OWNED); 1273 1274 /* 1275 * If we know that the lock we are acquiring comes after 1276 * the lock we most recently acquired in the lock order tree, 1277 * then there is no need for any further checks. 1278 */ 1279 if (isitmychild(w1, w)) 1280 goto out; 1281 1282 for (j = 0, lle = lock_list; lle != NULL; lle = lle->ll_next) { 1283 for (i = lle->ll_count - 1; i >= 0; i--, j++) { 1284 struct stack pstack; 1285 bool pstackv, trace; 1286 1287 MPASS(j < LOCK_CHILDCOUNT * LOCK_NCHILDREN); 1288 lock1 = &lle->ll_children[i]; 1289 1290 /* 1291 * Ignore the interlock. 1292 */ 1293 if (interlock == lock1->li_lock) 1294 continue; 1295 1296 /* 1297 * If this lock doesn't undergo witness checking, 1298 * then skip it. 1299 */ 1300 w1 = lock1->li_lock->lo_witness; 1301 if (w1 == NULL) { 1302 KASSERT((lock1->li_lock->lo_flags & LO_WITNESS) == 0, 1303 ("lock missing witness structure")); 1304 continue; 1305 } 1306 1307 /* 1308 * If we are locking Giant and this is a sleepable 1309 * lock, then skip it. 1310 */ 1311 if ((lock1->li_flags & LI_SLEEPABLE) != 0 && 1312 lock == &Giant.lock_object) 1313 continue; 1314 1315 /* 1316 * If we are locking a sleepable lock and this lock 1317 * is Giant, then skip it. 1318 */ 1319 if ((lock->lo_flags & LO_SLEEPABLE) != 0 && 1320 (flags & LOP_NOSLEEP) == 0 && 1321 lock1->li_lock == &Giant.lock_object) 1322 continue; 1323 1324 /* 1325 * If we are locking a sleepable lock and this lock 1326 * isn't sleepable, we want to treat it as a lock 1327 * order violation to enfore a general lock order of 1328 * sleepable locks before non-sleepable locks. 1329 */ 1330 if ((lock->lo_flags & LO_SLEEPABLE) != 0 && 1331 (flags & LOP_NOSLEEP) == 0 && 1332 (lock1->li_flags & LI_SLEEPABLE) == 0) 1333 goto reversal; 1334 1335 /* 1336 * If we are locking Giant and this is a non-sleepable 1337 * lock, then treat it as a reversal. 1338 */ 1339 if ((lock1->li_flags & LI_SLEEPABLE) == 0 && 1340 lock == &Giant.lock_object) 1341 goto reversal; 1342 1343 /* 1344 * Check the lock order hierarchy for a reveresal. 1345 */ 1346 if (!isitmydescendant(w, w1)) 1347 continue; 1348 reversal: 1349 1350 /* 1351 * We have a lock order violation, check to see if it 1352 * is allowed or has already been yelled about. 1353 */ 1354 1355 /* Bail if this violation is known */ 1356 if (w_rmatrix[w1->w_index][w->w_index] & WITNESS_REVERSAL) 1357 goto out; 1358 1359 /* Record this as a violation */ 1360 w_rmatrix[w1->w_index][w->w_index] |= WITNESS_REVERSAL; 1361 w_rmatrix[w->w_index][w1->w_index] |= WITNESS_REVERSAL; 1362 w->w_reversed = w1->w_reversed = 1; 1363 witness_increment_graph_generation(); 1364 1365 /* 1366 * If the lock order is blessed, bail before logging 1367 * anything. We don't look for other lock order 1368 * violations though, which may be a bug. 1369 */ 1370 if (blessed(w, w1)) 1371 goto out; 1372 1373 trace = atomic_load_int(&witness_trace); 1374 if (trace) { 1375 struct witness_lock_order_data *data; 1376 1377 pstackv = false; 1378 data = witness_lock_order_get(w, w1); 1379 if (data != NULL) { 1380 stack_copy(&data->wlod_stack, 1381 &pstack); 1382 pstackv = true; 1383 } 1384 } 1385 mtx_unlock_spin(&w_mtx); 1386 1387 #ifdef WITNESS_NO_VNODE 1388 /* 1389 * There are known LORs between VNODE locks. They are 1390 * not an indication of a bug. VNODE locks are flagged 1391 * as such (LO_IS_VNODE) and we don't yell if the LOR 1392 * is between 2 VNODE locks. 1393 */ 1394 if ((lock->lo_flags & LO_IS_VNODE) != 0 && 1395 (lock1->li_lock->lo_flags & LO_IS_VNODE) != 0) 1396 return; 1397 #endif 1398 1399 /* 1400 * Ok, yell about it. 1401 */ 1402 if ((lock->lo_flags & LO_SLEEPABLE) != 0 && 1403 (flags & LOP_NOSLEEP) == 0 && 1404 (lock1->li_flags & LI_SLEEPABLE) == 0) 1405 witness_output( 1406 "lock order reversal: (sleepable after non-sleepable)\n"); 1407 else if ((lock1->li_flags & LI_SLEEPABLE) == 0 1408 && lock == &Giant.lock_object) 1409 witness_output( 1410 "lock order reversal: (Giant after non-sleepable)\n"); 1411 else 1412 witness_output("lock order reversal:\n"); 1413 1414 /* 1415 * Try to locate an earlier lock with 1416 * witness w in our list. 1417 */ 1418 do { 1419 lock2 = &lle->ll_children[i]; 1420 MPASS(lock2->li_lock != NULL); 1421 if (lock2->li_lock->lo_witness == w) 1422 break; 1423 if (i == 0 && lle->ll_next != NULL) { 1424 lle = lle->ll_next; 1425 i = lle->ll_count - 1; 1426 MPASS(i >= 0 && i < LOCK_NCHILDREN); 1427 } else 1428 i--; 1429 } while (i >= 0); 1430 if (i < 0) { 1431 witness_output(" 1st %p %s (%s, %s) @ %s:%d\n", 1432 lock1->li_lock, lock1->li_lock->lo_name, 1433 w1->w_name, w1->w_class->lc_name, 1434 fixup_filename(lock1->li_file), 1435 lock1->li_line); 1436 witness_output(" 2nd %p %s (%s, %s) @ %s:%d\n", 1437 lock, lock->lo_name, w->w_name, 1438 w->w_class->lc_name, fixup_filename(file), 1439 line); 1440 } else { 1441 struct witness *w2 = lock2->li_lock->lo_witness; 1442 1443 witness_output(" 1st %p %s (%s, %s) @ %s:%d\n", 1444 lock2->li_lock, lock2->li_lock->lo_name, 1445 w2->w_name, w2->w_class->lc_name, 1446 fixup_filename(lock2->li_file), 1447 lock2->li_line); 1448 witness_output(" 2nd %p %s (%s, %s) @ %s:%d\n", 1449 lock1->li_lock, lock1->li_lock->lo_name, 1450 w1->w_name, w1->w_class->lc_name, 1451 fixup_filename(lock1->li_file), 1452 lock1->li_line); 1453 witness_output(" 3rd %p %s (%s, %s) @ %s:%d\n", lock, 1454 lock->lo_name, w->w_name, 1455 w->w_class->lc_name, fixup_filename(file), 1456 line); 1457 } 1458 if (trace) { 1459 char buf[64]; 1460 struct sbuf sb; 1461 1462 sbuf_new(&sb, buf, sizeof(buf), SBUF_FIXEDLEN); 1463 sbuf_set_drain(&sb, witness_output_drain, 1464 NULL); 1465 1466 if (pstackv) { 1467 sbuf_printf(&sb, 1468 "lock order %s -> %s established at:\n", 1469 w->w_name, w1->w_name); 1470 stack_sbuf_print_flags(&sb, &pstack, 1471 M_NOWAIT, STACK_SBUF_FMT_LONG); 1472 } 1473 1474 sbuf_printf(&sb, 1475 "lock order %s -> %s attempted at:\n", 1476 w1->w_name, w->w_name); 1477 stack_save(&pstack); 1478 stack_sbuf_print_flags(&sb, &pstack, M_NOWAIT, 1479 STACK_SBUF_FMT_LONG); 1480 1481 sbuf_finish(&sb); 1482 sbuf_delete(&sb); 1483 } 1484 witness_enter_debugger(__func__); 1485 return; 1486 } 1487 } 1488 1489 /* 1490 * If requested, build a new lock order. However, don't build a new 1491 * relationship between a sleepable lock and Giant if it is in the 1492 * wrong direction. The correct lock order is that sleepable locks 1493 * always come before Giant. 1494 */ 1495 if (flags & LOP_NEWORDER && 1496 !(plock->li_lock == &Giant.lock_object && 1497 (lock->lo_flags & LO_SLEEPABLE) != 0 && 1498 (flags & LOP_NOSLEEP) == 0)) { 1499 CTR3(KTR_WITNESS, "%s: adding %s as a child of %s", __func__, 1500 w->w_name, plock->li_lock->lo_witness->w_name); 1501 itismychild(plock->li_lock->lo_witness, w); 1502 } 1503 out: 1504 mtx_unlock_spin(&w_mtx); 1505 } 1506 1507 void 1508 witness_lock(struct lock_object *lock, int flags, const char *file, int line) 1509 { 1510 struct lock_list_entry **lock_list, *lle; 1511 struct lock_instance *instance; 1512 struct witness *w; 1513 struct thread *td; 1514 1515 if (witness_cold || witness_watch == -1 || lock->lo_witness == NULL || 1516 KERNEL_PANICKED()) 1517 return; 1518 w = lock->lo_witness; 1519 td = curthread; 1520 1521 /* Determine lock list for this lock. */ 1522 if (LOCK_CLASS(lock)->lc_flags & LC_SLEEPLOCK) 1523 lock_list = &td->td_sleeplocks; 1524 else 1525 lock_list = PCPU_PTR(spinlocks); 1526 1527 /* Check to see if we are recursing on a lock we already own. */ 1528 instance = find_instance(*lock_list, lock); 1529 if (instance != NULL) { 1530 instance->li_flags++; 1531 CTR4(KTR_WITNESS, "%s: pid %d recursed on %s r=%d", __func__, 1532 td->td_proc->p_pid, lock->lo_name, 1533 instance->li_flags & LI_RECURSEMASK); 1534 instance->li_file = file; 1535 instance->li_line = line; 1536 return; 1537 } 1538 1539 /* Update per-witness last file and line acquire. */ 1540 w->w_file = file; 1541 w->w_line = line; 1542 1543 /* Find the next open lock instance in the list and fill it. */ 1544 lle = *lock_list; 1545 if (lle == NULL || lle->ll_count == LOCK_NCHILDREN) { 1546 lle = witness_lock_list_get(); 1547 if (lle == NULL) 1548 return; 1549 lle->ll_next = *lock_list; 1550 CTR3(KTR_WITNESS, "%s: pid %d added lle %p", __func__, 1551 td->td_proc->p_pid, lle); 1552 *lock_list = lle; 1553 } 1554 instance = &lle->ll_children[lle->ll_count++]; 1555 instance->li_lock = lock; 1556 instance->li_line = line; 1557 instance->li_file = file; 1558 instance->li_flags = 0; 1559 if ((flags & LOP_EXCLUSIVE) != 0) 1560 instance->li_flags |= LI_EXCLUSIVE; 1561 if ((lock->lo_flags & LO_SLEEPABLE) != 0 && (flags & LOP_NOSLEEP) == 0) 1562 instance->li_flags |= LI_SLEEPABLE; 1563 CTR4(KTR_WITNESS, "%s: pid %d added %s as lle[%d]", __func__, 1564 td->td_proc->p_pid, lock->lo_name, lle->ll_count - 1); 1565 } 1566 1567 void 1568 witness_upgrade(struct lock_object *lock, int flags, const char *file, int line) 1569 { 1570 struct lock_instance *instance; 1571 struct lock_class *class; 1572 1573 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); 1574 if (lock->lo_witness == NULL || witness_watch == -1 || KERNEL_PANICKED()) 1575 return; 1576 class = LOCK_CLASS(lock); 1577 if (witness_watch) { 1578 if ((lock->lo_flags & LO_UPGRADABLE) == 0) 1579 kassert_panic( 1580 "upgrade of non-upgradable lock (%s) %s @ %s:%d", 1581 class->lc_name, lock->lo_name, 1582 fixup_filename(file), line); 1583 if ((class->lc_flags & LC_SLEEPLOCK) == 0) 1584 kassert_panic( 1585 "upgrade of non-sleep lock (%s) %s @ %s:%d", 1586 class->lc_name, lock->lo_name, 1587 fixup_filename(file), line); 1588 } 1589 instance = find_instance(curthread->td_sleeplocks, lock); 1590 if (instance == NULL) { 1591 kassert_panic("upgrade of unlocked lock (%s) %s @ %s:%d", 1592 class->lc_name, lock->lo_name, 1593 fixup_filename(file), line); 1594 return; 1595 } 1596 if (witness_watch) { 1597 if ((instance->li_flags & LI_EXCLUSIVE) != 0) 1598 kassert_panic( 1599 "upgrade of exclusive lock (%s) %s @ %s:%d", 1600 class->lc_name, lock->lo_name, 1601 fixup_filename(file), line); 1602 if ((instance->li_flags & LI_RECURSEMASK) != 0) 1603 kassert_panic( 1604 "upgrade of recursed lock (%s) %s r=%d @ %s:%d", 1605 class->lc_name, lock->lo_name, 1606 instance->li_flags & LI_RECURSEMASK, 1607 fixup_filename(file), line); 1608 } 1609 instance->li_flags |= LI_EXCLUSIVE; 1610 } 1611 1612 void 1613 witness_downgrade(struct lock_object *lock, int flags, const char *file, 1614 int line) 1615 { 1616 struct lock_instance *instance; 1617 struct lock_class *class; 1618 1619 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); 1620 if (lock->lo_witness == NULL || witness_watch == -1 || KERNEL_PANICKED()) 1621 return; 1622 class = LOCK_CLASS(lock); 1623 if (witness_watch) { 1624 if ((lock->lo_flags & LO_UPGRADABLE) == 0) 1625 kassert_panic( 1626 "downgrade of non-upgradable lock (%s) %s @ %s:%d", 1627 class->lc_name, lock->lo_name, 1628 fixup_filename(file), line); 1629 if ((class->lc_flags & LC_SLEEPLOCK) == 0) 1630 kassert_panic( 1631 "downgrade of non-sleep lock (%s) %s @ %s:%d", 1632 class->lc_name, lock->lo_name, 1633 fixup_filename(file), line); 1634 } 1635 instance = find_instance(curthread->td_sleeplocks, lock); 1636 if (instance == NULL) { 1637 kassert_panic("downgrade of unlocked lock (%s) %s @ %s:%d", 1638 class->lc_name, lock->lo_name, 1639 fixup_filename(file), line); 1640 return; 1641 } 1642 if (witness_watch) { 1643 if ((instance->li_flags & LI_EXCLUSIVE) == 0) 1644 kassert_panic( 1645 "downgrade of shared lock (%s) %s @ %s:%d", 1646 class->lc_name, lock->lo_name, 1647 fixup_filename(file), line); 1648 if ((instance->li_flags & LI_RECURSEMASK) != 0) 1649 kassert_panic( 1650 "downgrade of recursed lock (%s) %s r=%d @ %s:%d", 1651 class->lc_name, lock->lo_name, 1652 instance->li_flags & LI_RECURSEMASK, 1653 fixup_filename(file), line); 1654 } 1655 instance->li_flags &= ~LI_EXCLUSIVE; 1656 } 1657 1658 void 1659 witness_unlock(struct lock_object *lock, int flags, const char *file, int line) 1660 { 1661 struct lock_list_entry **lock_list, *lle; 1662 struct lock_instance *instance; 1663 struct lock_class *class; 1664 struct thread *td; 1665 register_t s; 1666 int i, j; 1667 1668 if (witness_cold || lock->lo_witness == NULL || KERNEL_PANICKED()) 1669 return; 1670 td = curthread; 1671 class = LOCK_CLASS(lock); 1672 1673 /* Find lock instance associated with this lock. */ 1674 if (class->lc_flags & LC_SLEEPLOCK) 1675 lock_list = &td->td_sleeplocks; 1676 else 1677 lock_list = PCPU_PTR(spinlocks); 1678 lle = *lock_list; 1679 for (; *lock_list != NULL; lock_list = &(*lock_list)->ll_next) 1680 for (i = 0; i < (*lock_list)->ll_count; i++) { 1681 instance = &(*lock_list)->ll_children[i]; 1682 if (instance->li_lock == lock) 1683 goto found; 1684 } 1685 1686 /* 1687 * When disabling WITNESS through witness_watch we could end up in 1688 * having registered locks in the td_sleeplocks queue. 1689 * We have to make sure we flush these queues, so just search for 1690 * eventual register locks and remove them. 1691 */ 1692 if (witness_watch > 0) { 1693 kassert_panic("lock (%s) %s not locked @ %s:%d", class->lc_name, 1694 lock->lo_name, fixup_filename(file), line); 1695 return; 1696 } else { 1697 return; 1698 } 1699 found: 1700 1701 /* First, check for shared/exclusive mismatches. */ 1702 if ((instance->li_flags & LI_EXCLUSIVE) != 0 && witness_watch > 0 && 1703 (flags & LOP_EXCLUSIVE) == 0) { 1704 witness_output("shared unlock of (%s) %s @ %s:%d\n", 1705 class->lc_name, lock->lo_name, fixup_filename(file), line); 1706 witness_output("while exclusively locked from %s:%d\n", 1707 fixup_filename(instance->li_file), instance->li_line); 1708 kassert_panic("excl->ushare"); 1709 } 1710 if ((instance->li_flags & LI_EXCLUSIVE) == 0 && witness_watch > 0 && 1711 (flags & LOP_EXCLUSIVE) != 0) { 1712 witness_output("exclusive unlock of (%s) %s @ %s:%d\n", 1713 class->lc_name, lock->lo_name, fixup_filename(file), line); 1714 witness_output("while share locked from %s:%d\n", 1715 fixup_filename(instance->li_file), 1716 instance->li_line); 1717 kassert_panic("share->uexcl"); 1718 } 1719 /* If we are recursed, unrecurse. */ 1720 if ((instance->li_flags & LI_RECURSEMASK) > 0) { 1721 CTR4(KTR_WITNESS, "%s: pid %d unrecursed on %s r=%d", __func__, 1722 td->td_proc->p_pid, instance->li_lock->lo_name, 1723 instance->li_flags); 1724 instance->li_flags--; 1725 return; 1726 } 1727 /* The lock is now being dropped, check for NORELEASE flag */ 1728 if ((instance->li_flags & LI_NORELEASE) != 0 && witness_watch > 0) { 1729 witness_output("forbidden unlock of (%s) %s @ %s:%d\n", 1730 class->lc_name, lock->lo_name, fixup_filename(file), line); 1731 kassert_panic("lock marked norelease"); 1732 } 1733 1734 /* Otherwise, remove this item from the list. */ 1735 s = intr_disable(); 1736 CTR4(KTR_WITNESS, "%s: pid %d removed %s from lle[%d]", __func__, 1737 td->td_proc->p_pid, instance->li_lock->lo_name, 1738 (*lock_list)->ll_count - 1); 1739 for (j = i; j < (*lock_list)->ll_count - 1; j++) 1740 (*lock_list)->ll_children[j] = 1741 (*lock_list)->ll_children[j + 1]; 1742 (*lock_list)->ll_count--; 1743 intr_restore(s); 1744 1745 /* 1746 * In order to reduce contention on w_mtx, we want to keep always an 1747 * head object into lists so that frequent allocation from the 1748 * free witness pool (and subsequent locking) is avoided. 1749 * In order to maintain the current code simple, when the head 1750 * object is totally unloaded it means also that we do not have 1751 * further objects in the list, so the list ownership needs to be 1752 * hand over to another object if the current head needs to be freed. 1753 */ 1754 if ((*lock_list)->ll_count == 0) { 1755 if (*lock_list == lle) { 1756 if (lle->ll_next == NULL) 1757 return; 1758 } else 1759 lle = *lock_list; 1760 *lock_list = lle->ll_next; 1761 CTR3(KTR_WITNESS, "%s: pid %d removed lle %p", __func__, 1762 td->td_proc->p_pid, lle); 1763 witness_lock_list_free(lle); 1764 } 1765 } 1766 1767 void 1768 witness_thread_exit(struct thread *td) 1769 { 1770 struct lock_list_entry *lle; 1771 int i, n; 1772 1773 lle = td->td_sleeplocks; 1774 if (lle == NULL || KERNEL_PANICKED()) 1775 return; 1776 if (lle->ll_count != 0) { 1777 for (n = 0; lle != NULL; lle = lle->ll_next) 1778 for (i = lle->ll_count - 1; i >= 0; i--) { 1779 if (n == 0) 1780 witness_output( 1781 "Thread %p exiting with the following locks held:\n", td); 1782 n++; 1783 witness_list_lock(&lle->ll_children[i], 1784 witness_output); 1785 1786 } 1787 kassert_panic( 1788 "Thread %p cannot exit while holding sleeplocks\n", td); 1789 } 1790 witness_lock_list_free(lle); 1791 } 1792 1793 /* 1794 * Warn if any locks other than 'lock' are held. Flags can be passed in to 1795 * exempt Giant and sleepable locks from the checks as well. If any 1796 * non-exempt locks are held, then a supplied message is printed to the 1797 * output channel along with a list of the offending locks. If indicated in the 1798 * flags then a failure results in a panic as well. 1799 */ 1800 int 1801 witness_warn(int flags, struct lock_object *lock, const char *fmt, ...) 1802 { 1803 struct lock_list_entry *lock_list, *lle; 1804 struct lock_instance *lock1; 1805 struct thread *td; 1806 va_list ap; 1807 int i, n; 1808 1809 if (witness_cold || witness_watch < 1 || KERNEL_PANICKED()) 1810 return (0); 1811 n = 0; 1812 td = curthread; 1813 for (lle = td->td_sleeplocks; lle != NULL; lle = lle->ll_next) 1814 for (i = lle->ll_count - 1; i >= 0; i--) { 1815 lock1 = &lle->ll_children[i]; 1816 if (lock1->li_lock == lock) 1817 continue; 1818 if (flags & WARN_GIANTOK && 1819 lock1->li_lock == &Giant.lock_object) 1820 continue; 1821 if (flags & WARN_SLEEPOK && 1822 (lock1->li_flags & LI_SLEEPABLE) != 0) 1823 continue; 1824 if (n == 0) { 1825 va_start(ap, fmt); 1826 vprintf(fmt, ap); 1827 va_end(ap); 1828 printf(" with the following %slocks held:\n", 1829 (flags & WARN_SLEEPOK) != 0 ? 1830 "non-sleepable " : ""); 1831 } 1832 n++; 1833 witness_list_lock(lock1, printf); 1834 } 1835 1836 /* 1837 * Pin the thread in order to avoid problems with thread migration. 1838 * Once that all verifies are passed about spinlocks ownership, 1839 * the thread is in a safe path and it can be unpinned. 1840 */ 1841 sched_pin(); 1842 lock_list = PCPU_GET(spinlocks); 1843 if (lock_list != NULL && lock_list->ll_count != 0) { 1844 sched_unpin(); 1845 1846 /* 1847 * We should only have one spinlock and as long as 1848 * the flags cannot match for this locks class, 1849 * check if the first spinlock is the one curthread 1850 * should hold. 1851 */ 1852 lock1 = &lock_list->ll_children[lock_list->ll_count - 1]; 1853 if (lock_list->ll_count == 1 && lock_list->ll_next == NULL && 1854 lock1->li_lock == lock && n == 0) 1855 return (0); 1856 1857 va_start(ap, fmt); 1858 vprintf(fmt, ap); 1859 va_end(ap); 1860 printf(" with the following %slocks held:\n", 1861 (flags & WARN_SLEEPOK) != 0 ? "non-sleepable " : ""); 1862 n += witness_list_locks(&lock_list, printf); 1863 } else 1864 sched_unpin(); 1865 if (flags & WARN_PANIC && n) 1866 kassert_panic("%s", __func__); 1867 else 1868 witness_debugger(n, __func__); 1869 return (n); 1870 } 1871 1872 const char * 1873 witness_file(struct lock_object *lock) 1874 { 1875 struct witness *w; 1876 1877 if (witness_cold || witness_watch < 1 || lock->lo_witness == NULL) 1878 return ("?"); 1879 w = lock->lo_witness; 1880 return (w->w_file); 1881 } 1882 1883 int 1884 witness_line(struct lock_object *lock) 1885 { 1886 struct witness *w; 1887 1888 if (witness_cold || witness_watch < 1 || lock->lo_witness == NULL) 1889 return (0); 1890 w = lock->lo_witness; 1891 return (w->w_line); 1892 } 1893 1894 static struct witness * 1895 enroll(const char *description, struct lock_class *lock_class) 1896 { 1897 struct witness *w; 1898 1899 MPASS(description != NULL); 1900 1901 if (witness_watch == -1 || KERNEL_PANICKED()) 1902 return (NULL); 1903 if ((lock_class->lc_flags & LC_SPINLOCK)) { 1904 if (witness_skipspin) 1905 return (NULL); 1906 } else if ((lock_class->lc_flags & LC_SLEEPLOCK) == 0) { 1907 kassert_panic("lock class %s is not sleep or spin", 1908 lock_class->lc_name); 1909 return (NULL); 1910 } 1911 1912 mtx_lock_spin(&w_mtx); 1913 w = witness_hash_get(description); 1914 if (w) 1915 goto found; 1916 if ((w = witness_get()) == NULL) 1917 return (NULL); 1918 MPASS(strlen(description) < MAX_W_NAME); 1919 strcpy(w->w_name, description); 1920 w->w_class = lock_class; 1921 w->w_refcount = 1; 1922 STAILQ_INSERT_HEAD(&w_all, w, w_list); 1923 if (lock_class->lc_flags & LC_SPINLOCK) { 1924 STAILQ_INSERT_HEAD(&w_spin, w, w_typelist); 1925 w_spin_cnt++; 1926 } else if (lock_class->lc_flags & LC_SLEEPLOCK) { 1927 STAILQ_INSERT_HEAD(&w_sleep, w, w_typelist); 1928 w_sleep_cnt++; 1929 } 1930 1931 /* Insert new witness into the hash */ 1932 witness_hash_put(w); 1933 witness_increment_graph_generation(); 1934 mtx_unlock_spin(&w_mtx); 1935 return (w); 1936 found: 1937 w->w_refcount++; 1938 if (w->w_refcount == 1) 1939 w->w_class = lock_class; 1940 mtx_unlock_spin(&w_mtx); 1941 if (lock_class != w->w_class) 1942 kassert_panic( 1943 "lock (%s) %s does not match earlier (%s) lock", 1944 description, lock_class->lc_name, 1945 w->w_class->lc_name); 1946 return (w); 1947 } 1948 1949 static void 1950 depart(struct witness *w) 1951 { 1952 1953 MPASS(w->w_refcount == 0); 1954 if (w->w_class->lc_flags & LC_SLEEPLOCK) { 1955 w_sleep_cnt--; 1956 } else { 1957 w_spin_cnt--; 1958 } 1959 /* 1960 * Set file to NULL as it may point into a loadable module. 1961 */ 1962 w->w_file = NULL; 1963 w->w_line = 0; 1964 witness_increment_graph_generation(); 1965 } 1966 1967 static void 1968 adopt(struct witness *parent, struct witness *child) 1969 { 1970 int pi, ci, i, j; 1971 1972 if (witness_cold == 0) 1973 mtx_assert(&w_mtx, MA_OWNED); 1974 1975 /* If the relationship is already known, there's no work to be done. */ 1976 if (isitmychild(parent, child)) 1977 return; 1978 1979 /* When the structure of the graph changes, bump up the generation. */ 1980 witness_increment_graph_generation(); 1981 1982 /* 1983 * The hard part ... create the direct relationship, then propagate all 1984 * indirect relationships. 1985 */ 1986 pi = parent->w_index; 1987 ci = child->w_index; 1988 WITNESS_INDEX_ASSERT(pi); 1989 WITNESS_INDEX_ASSERT(ci); 1990 MPASS(pi != ci); 1991 w_rmatrix[pi][ci] |= WITNESS_PARENT; 1992 w_rmatrix[ci][pi] |= WITNESS_CHILD; 1993 1994 /* 1995 * If parent was not already an ancestor of child, 1996 * then we increment the descendant and ancestor counters. 1997 */ 1998 if ((w_rmatrix[pi][ci] & WITNESS_ANCESTOR) == 0) { 1999 parent->w_num_descendants++; 2000 child->w_num_ancestors++; 2001 } 2002 2003 /* 2004 * Find each ancestor of 'pi'. Note that 'pi' itself is counted as 2005 * an ancestor of 'pi' during this loop. 2006 */ 2007 for (i = 1; i <= w_max_used_index; i++) { 2008 if ((w_rmatrix[i][pi] & WITNESS_ANCESTOR_MASK) == 0 && 2009 (i != pi)) 2010 continue; 2011 2012 /* Find each descendant of 'i' and mark it as a descendant. */ 2013 for (j = 1; j <= w_max_used_index; j++) { 2014 /* 2015 * Skip children that are already marked as 2016 * descendants of 'i'. 2017 */ 2018 if (w_rmatrix[i][j] & WITNESS_ANCESTOR_MASK) 2019 continue; 2020 2021 /* 2022 * We are only interested in descendants of 'ci'. Note 2023 * that 'ci' itself is counted as a descendant of 'ci'. 2024 */ 2025 if ((w_rmatrix[ci][j] & WITNESS_ANCESTOR_MASK) == 0 && 2026 (j != ci)) 2027 continue; 2028 w_rmatrix[i][j] |= WITNESS_ANCESTOR; 2029 w_rmatrix[j][i] |= WITNESS_DESCENDANT; 2030 w_data[i].w_num_descendants++; 2031 w_data[j].w_num_ancestors++; 2032 2033 /* 2034 * Make sure we aren't marking a node as both an 2035 * ancestor and descendant. We should have caught 2036 * this as a lock order reversal earlier. 2037 */ 2038 if ((w_rmatrix[i][j] & WITNESS_ANCESTOR_MASK) && 2039 (w_rmatrix[i][j] & WITNESS_DESCENDANT_MASK)) { 2040 printf("witness rmatrix paradox! [%d][%d]=%d " 2041 "both ancestor and descendant\n", 2042 i, j, w_rmatrix[i][j]); 2043 kdb_backtrace(); 2044 printf("Witness disabled.\n"); 2045 witness_watch = -1; 2046 } 2047 if ((w_rmatrix[j][i] & WITNESS_ANCESTOR_MASK) && 2048 (w_rmatrix[j][i] & WITNESS_DESCENDANT_MASK)) { 2049 printf("witness rmatrix paradox! [%d][%d]=%d " 2050 "both ancestor and descendant\n", 2051 j, i, w_rmatrix[j][i]); 2052 kdb_backtrace(); 2053 printf("Witness disabled.\n"); 2054 witness_watch = -1; 2055 } 2056 } 2057 } 2058 } 2059 2060 static void 2061 itismychild(struct witness *parent, struct witness *child) 2062 { 2063 int unlocked; 2064 2065 MPASS(child != NULL && parent != NULL); 2066 if (witness_cold == 0) 2067 mtx_assert(&w_mtx, MA_OWNED); 2068 2069 if (!witness_lock_type_equal(parent, child)) { 2070 if (witness_cold == 0) { 2071 unlocked = 1; 2072 mtx_unlock_spin(&w_mtx); 2073 } else { 2074 unlocked = 0; 2075 } 2076 kassert_panic( 2077 "%s: parent \"%s\" (%s) and child \"%s\" (%s) are not " 2078 "the same lock type", __func__, parent->w_name, 2079 parent->w_class->lc_name, child->w_name, 2080 child->w_class->lc_name); 2081 if (unlocked) 2082 mtx_lock_spin(&w_mtx); 2083 } 2084 adopt(parent, child); 2085 } 2086 2087 /* 2088 * Generic code for the isitmy*() functions. The rmask parameter is the 2089 * expected relationship of w1 to w2. 2090 */ 2091 static int 2092 _isitmyx(struct witness *w1, struct witness *w2, int rmask, const char *fname) 2093 { 2094 unsigned char r1, r2; 2095 int i1, i2; 2096 2097 i1 = w1->w_index; 2098 i2 = w2->w_index; 2099 WITNESS_INDEX_ASSERT(i1); 2100 WITNESS_INDEX_ASSERT(i2); 2101 r1 = w_rmatrix[i1][i2] & WITNESS_RELATED_MASK; 2102 r2 = w_rmatrix[i2][i1] & WITNESS_RELATED_MASK; 2103 2104 /* The flags on one better be the inverse of the flags on the other */ 2105 if (!((WITNESS_ATOD(r1) == r2 && WITNESS_DTOA(r2) == r1) || 2106 (WITNESS_DTOA(r1) == r2 && WITNESS_ATOD(r2) == r1))) { 2107 /* Don't squawk if we're potentially racing with an update. */ 2108 if (!mtx_owned(&w_mtx)) 2109 return (0); 2110 printf("%s: rmatrix mismatch between %s (index %d) and %s " 2111 "(index %d): w_rmatrix[%d][%d] == %hhx but " 2112 "w_rmatrix[%d][%d] == %hhx\n", 2113 fname, w1->w_name, i1, w2->w_name, i2, i1, i2, r1, 2114 i2, i1, r2); 2115 kdb_backtrace(); 2116 printf("Witness disabled.\n"); 2117 witness_watch = -1; 2118 } 2119 return (r1 & rmask); 2120 } 2121 2122 /* 2123 * Checks if @child is a direct child of @parent. 2124 */ 2125 static int 2126 isitmychild(struct witness *parent, struct witness *child) 2127 { 2128 2129 return (_isitmyx(parent, child, WITNESS_PARENT, __func__)); 2130 } 2131 2132 /* 2133 * Checks if @descendant is a direct or inderect descendant of @ancestor. 2134 */ 2135 static int 2136 isitmydescendant(struct witness *ancestor, struct witness *descendant) 2137 { 2138 2139 return (_isitmyx(ancestor, descendant, WITNESS_ANCESTOR_MASK, 2140 __func__)); 2141 } 2142 2143 static int 2144 blessed(struct witness *w1, struct witness *w2) 2145 { 2146 int i; 2147 struct witness_blessed *b; 2148 2149 for (i = 0; i < nitems(blessed_list); i++) { 2150 b = &blessed_list[i]; 2151 if (strcmp(w1->w_name, b->b_lock1) == 0) { 2152 if (strcmp(w2->w_name, b->b_lock2) == 0) 2153 return (1); 2154 continue; 2155 } 2156 if (strcmp(w1->w_name, b->b_lock2) == 0) 2157 if (strcmp(w2->w_name, b->b_lock1) == 0) 2158 return (1); 2159 } 2160 return (0); 2161 } 2162 2163 static struct witness * 2164 witness_get(void) 2165 { 2166 struct witness *w; 2167 int index; 2168 2169 if (witness_cold == 0) 2170 mtx_assert(&w_mtx, MA_OWNED); 2171 2172 if (witness_watch == -1) { 2173 mtx_unlock_spin(&w_mtx); 2174 return (NULL); 2175 } 2176 if (STAILQ_EMPTY(&w_free)) { 2177 witness_watch = -1; 2178 mtx_unlock_spin(&w_mtx); 2179 printf("WITNESS: unable to allocate a new witness object\n"); 2180 return (NULL); 2181 } 2182 w = STAILQ_FIRST(&w_free); 2183 STAILQ_REMOVE_HEAD(&w_free, w_list); 2184 w_free_cnt--; 2185 index = w->w_index; 2186 MPASS(index > 0 && index == w_max_used_index+1 && 2187 index < witness_count); 2188 bzero(w, sizeof(*w)); 2189 w->w_index = index; 2190 if (index > w_max_used_index) 2191 w_max_used_index = index; 2192 return (w); 2193 } 2194 2195 static void 2196 witness_free(struct witness *w) 2197 { 2198 2199 STAILQ_INSERT_HEAD(&w_free, w, w_list); 2200 w_free_cnt++; 2201 } 2202 2203 static struct lock_list_entry * 2204 witness_lock_list_get(void) 2205 { 2206 struct lock_list_entry *lle; 2207 2208 if (witness_watch == -1) 2209 return (NULL); 2210 mtx_lock_spin(&w_mtx); 2211 lle = w_lock_list_free; 2212 if (lle == NULL) { 2213 witness_watch = -1; 2214 mtx_unlock_spin(&w_mtx); 2215 printf("%s: witness exhausted\n", __func__); 2216 return (NULL); 2217 } 2218 w_lock_list_free = lle->ll_next; 2219 mtx_unlock_spin(&w_mtx); 2220 bzero(lle, sizeof(*lle)); 2221 return (lle); 2222 } 2223 2224 static void 2225 witness_lock_list_free(struct lock_list_entry *lle) 2226 { 2227 2228 mtx_lock_spin(&w_mtx); 2229 lle->ll_next = w_lock_list_free; 2230 w_lock_list_free = lle; 2231 mtx_unlock_spin(&w_mtx); 2232 } 2233 2234 static struct lock_instance * 2235 find_instance(struct lock_list_entry *list, const struct lock_object *lock) 2236 { 2237 struct lock_list_entry *lle; 2238 struct lock_instance *instance; 2239 int i; 2240 2241 for (lle = list; lle != NULL; lle = lle->ll_next) 2242 for (i = lle->ll_count - 1; i >= 0; i--) { 2243 instance = &lle->ll_children[i]; 2244 if (instance->li_lock == lock) 2245 return (instance); 2246 } 2247 return (NULL); 2248 } 2249 2250 static void 2251 witness_list_lock(struct lock_instance *instance, 2252 int (*prnt)(const char *fmt, ...)) 2253 { 2254 struct lock_object *lock; 2255 2256 lock = instance->li_lock; 2257 prnt("%s %s %s", (instance->li_flags & LI_EXCLUSIVE) != 0 ? 2258 "exclusive" : "shared", LOCK_CLASS(lock)->lc_name, lock->lo_name); 2259 if (lock->lo_witness->w_name != lock->lo_name) 2260 prnt(" (%s)", lock->lo_witness->w_name); 2261 prnt(" r = %d (%p) locked @ %s:%d\n", 2262 instance->li_flags & LI_RECURSEMASK, lock, 2263 fixup_filename(instance->li_file), instance->li_line); 2264 } 2265 2266 static int 2267 witness_output(const char *fmt, ...) 2268 { 2269 va_list ap; 2270 int ret; 2271 2272 va_start(ap, fmt); 2273 ret = witness_voutput(fmt, ap); 2274 va_end(ap); 2275 return (ret); 2276 } 2277 2278 static int 2279 witness_voutput(const char *fmt, va_list ap) 2280 { 2281 int ret; 2282 2283 ret = 0; 2284 switch (witness_channel) { 2285 case WITNESS_CONSOLE: 2286 ret = vprintf(fmt, ap); 2287 break; 2288 case WITNESS_LOG: 2289 vlog(LOG_NOTICE, fmt, ap); 2290 break; 2291 case WITNESS_NONE: 2292 break; 2293 } 2294 return (ret); 2295 } 2296 2297 #ifdef DDB 2298 static int 2299 witness_thread_has_locks(struct thread *td) 2300 { 2301 2302 if (td->td_sleeplocks == NULL) 2303 return (0); 2304 return (td->td_sleeplocks->ll_count != 0); 2305 } 2306 2307 static int 2308 witness_proc_has_locks(struct proc *p) 2309 { 2310 struct thread *td; 2311 2312 FOREACH_THREAD_IN_PROC(p, td) { 2313 if (witness_thread_has_locks(td)) 2314 return (1); 2315 } 2316 return (0); 2317 } 2318 #endif 2319 2320 int 2321 witness_list_locks(struct lock_list_entry **lock_list, 2322 int (*prnt)(const char *fmt, ...)) 2323 { 2324 struct lock_list_entry *lle; 2325 int i, nheld; 2326 2327 nheld = 0; 2328 for (lle = *lock_list; lle != NULL; lle = lle->ll_next) 2329 for (i = lle->ll_count - 1; i >= 0; i--) { 2330 witness_list_lock(&lle->ll_children[i], prnt); 2331 nheld++; 2332 } 2333 return (nheld); 2334 } 2335 2336 /* 2337 * This is a bit risky at best. We call this function when we have timed 2338 * out acquiring a spin lock, and we assume that the other CPU is stuck 2339 * with this lock held. So, we go groveling around in the other CPU's 2340 * per-cpu data to try to find the lock instance for this spin lock to 2341 * see when it was last acquired. 2342 */ 2343 void 2344 witness_display_spinlock(struct lock_object *lock, struct thread *owner, 2345 int (*prnt)(const char *fmt, ...)) 2346 { 2347 struct lock_instance *instance; 2348 struct pcpu *pc; 2349 2350 if (owner->td_critnest == 0 || owner->td_oncpu == NOCPU) 2351 return; 2352 pc = pcpu_find(owner->td_oncpu); 2353 instance = find_instance(pc->pc_spinlocks, lock); 2354 if (instance != NULL) 2355 witness_list_lock(instance, prnt); 2356 } 2357 2358 void 2359 witness_save(struct lock_object *lock, const char **filep, int *linep) 2360 { 2361 struct lock_list_entry *lock_list; 2362 struct lock_instance *instance; 2363 struct lock_class *class; 2364 2365 /* Initialize for KMSAN's benefit. */ 2366 *filep = NULL; 2367 *linep = 0; 2368 2369 /* 2370 * This function is used independently in locking code to deal with 2371 * Giant, SCHEDULER_STOPPED() check can be removed here after Giant 2372 * is gone. 2373 */ 2374 if (SCHEDULER_STOPPED()) 2375 return; 2376 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); 2377 if (lock->lo_witness == NULL || witness_watch == -1 || KERNEL_PANICKED()) 2378 return; 2379 class = LOCK_CLASS(lock); 2380 if (class->lc_flags & LC_SLEEPLOCK) 2381 lock_list = curthread->td_sleeplocks; 2382 else { 2383 if (witness_skipspin) 2384 return; 2385 lock_list = PCPU_GET(spinlocks); 2386 } 2387 instance = find_instance(lock_list, lock); 2388 if (instance == NULL) { 2389 kassert_panic("%s: lock (%s) %s not locked", __func__, 2390 class->lc_name, lock->lo_name); 2391 return; 2392 } 2393 *filep = instance->li_file; 2394 *linep = instance->li_line; 2395 } 2396 2397 void 2398 witness_restore(struct lock_object *lock, const char *file, int line) 2399 { 2400 struct lock_list_entry *lock_list; 2401 struct lock_instance *instance; 2402 struct lock_class *class; 2403 2404 /* 2405 * This function is used independently in locking code to deal with 2406 * Giant, SCHEDULER_STOPPED() check can be removed here after Giant 2407 * is gone. 2408 */ 2409 if (SCHEDULER_STOPPED()) 2410 return; 2411 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); 2412 if (lock->lo_witness == NULL || witness_watch == -1 || KERNEL_PANICKED()) 2413 return; 2414 class = LOCK_CLASS(lock); 2415 if (class->lc_flags & LC_SLEEPLOCK) 2416 lock_list = curthread->td_sleeplocks; 2417 else { 2418 if (witness_skipspin) 2419 return; 2420 lock_list = PCPU_GET(spinlocks); 2421 } 2422 instance = find_instance(lock_list, lock); 2423 if (instance == NULL) 2424 kassert_panic("%s: lock (%s) %s not locked", __func__, 2425 class->lc_name, lock->lo_name); 2426 lock->lo_witness->w_file = file; 2427 lock->lo_witness->w_line = line; 2428 if (instance == NULL) 2429 return; 2430 instance->li_file = file; 2431 instance->li_line = line; 2432 } 2433 2434 static bool 2435 witness_find_instance(const struct lock_object *lock, 2436 struct lock_instance **instance) 2437 { 2438 #ifdef INVARIANT_SUPPORT 2439 struct lock_class *class; 2440 2441 if (lock->lo_witness == NULL || witness_watch < 1 || KERNEL_PANICKED()) 2442 return (false); 2443 class = LOCK_CLASS(lock); 2444 if ((class->lc_flags & LC_SLEEPLOCK) != 0) { 2445 *instance = find_instance(curthread->td_sleeplocks, lock); 2446 return (true); 2447 } else if ((class->lc_flags & LC_SPINLOCK) != 0) { 2448 *instance = find_instance(PCPU_GET(spinlocks), lock); 2449 return (true); 2450 } else { 2451 kassert_panic("Lock (%s) %s is not sleep or spin!", 2452 class->lc_name, lock->lo_name); 2453 return (false); 2454 } 2455 #else 2456 return (false); 2457 #endif 2458 } 2459 2460 void 2461 witness_assert(const struct lock_object *lock, int flags, const char *file, 2462 int line) 2463 { 2464 #ifdef INVARIANT_SUPPORT 2465 struct lock_instance *instance; 2466 struct lock_class *class; 2467 2468 if (!witness_find_instance(lock, &instance)) 2469 return; 2470 class = LOCK_CLASS(lock); 2471 switch (flags) { 2472 case LA_UNLOCKED: 2473 if (instance != NULL) 2474 kassert_panic("Lock (%s) %s locked @ %s:%d.", 2475 class->lc_name, lock->lo_name, 2476 fixup_filename(file), line); 2477 break; 2478 case LA_LOCKED: 2479 case LA_LOCKED | LA_RECURSED: 2480 case LA_LOCKED | LA_NOTRECURSED: 2481 case LA_SLOCKED: 2482 case LA_SLOCKED | LA_RECURSED: 2483 case LA_SLOCKED | LA_NOTRECURSED: 2484 case LA_XLOCKED: 2485 case LA_XLOCKED | LA_RECURSED: 2486 case LA_XLOCKED | LA_NOTRECURSED: 2487 if (instance == NULL) { 2488 kassert_panic("Lock (%s) %s not locked @ %s:%d.", 2489 class->lc_name, lock->lo_name, 2490 fixup_filename(file), line); 2491 break; 2492 } 2493 if ((flags & LA_XLOCKED) != 0 && 2494 (instance->li_flags & LI_EXCLUSIVE) == 0) 2495 kassert_panic( 2496 "Lock (%s) %s not exclusively locked @ %s:%d.", 2497 class->lc_name, lock->lo_name, 2498 fixup_filename(file), line); 2499 if ((flags & LA_SLOCKED) != 0 && 2500 (instance->li_flags & LI_EXCLUSIVE) != 0) 2501 kassert_panic( 2502 "Lock (%s) %s exclusively locked @ %s:%d.", 2503 class->lc_name, lock->lo_name, 2504 fixup_filename(file), line); 2505 if ((flags & LA_RECURSED) != 0 && 2506 (instance->li_flags & LI_RECURSEMASK) == 0) 2507 kassert_panic("Lock (%s) %s not recursed @ %s:%d.", 2508 class->lc_name, lock->lo_name, 2509 fixup_filename(file), line); 2510 if ((flags & LA_NOTRECURSED) != 0 && 2511 (instance->li_flags & LI_RECURSEMASK) != 0) 2512 kassert_panic("Lock (%s) %s recursed @ %s:%d.", 2513 class->lc_name, lock->lo_name, 2514 fixup_filename(file), line); 2515 break; 2516 default: 2517 kassert_panic("Invalid lock assertion at %s:%d.", 2518 fixup_filename(file), line); 2519 } 2520 #endif /* INVARIANT_SUPPORT */ 2521 } 2522 2523 /* 2524 * Checks the ownership of the lock by curthread, consulting the witness list. 2525 * Returns: 2526 * 0 if witness is disabled or did not work 2527 * -1 if not owned 2528 * 1 if owned 2529 */ 2530 int 2531 witness_is_owned(const struct lock_object *lock) 2532 { 2533 #ifdef INVARIANT_SUPPORT 2534 struct lock_instance *instance; 2535 2536 if (!witness_find_instance(lock, &instance)) 2537 return (0); 2538 return (instance == NULL ? -1 : 1); 2539 #else 2540 return (0); 2541 #endif 2542 } 2543 2544 static void 2545 witness_setflag(struct lock_object *lock, int flag, int set) 2546 { 2547 struct lock_list_entry *lock_list; 2548 struct lock_instance *instance; 2549 struct lock_class *class; 2550 2551 if (lock->lo_witness == NULL || witness_watch == -1 || KERNEL_PANICKED()) 2552 return; 2553 class = LOCK_CLASS(lock); 2554 if (class->lc_flags & LC_SLEEPLOCK) 2555 lock_list = curthread->td_sleeplocks; 2556 else { 2557 if (witness_skipspin) 2558 return; 2559 lock_list = PCPU_GET(spinlocks); 2560 } 2561 instance = find_instance(lock_list, lock); 2562 if (instance == NULL) { 2563 kassert_panic("%s: lock (%s) %s not locked", __func__, 2564 class->lc_name, lock->lo_name); 2565 return; 2566 } 2567 2568 if (set) 2569 instance->li_flags |= flag; 2570 else 2571 instance->li_flags &= ~flag; 2572 } 2573 2574 void 2575 witness_norelease(struct lock_object *lock) 2576 { 2577 2578 witness_setflag(lock, LI_NORELEASE, 1); 2579 } 2580 2581 void 2582 witness_releaseok(struct lock_object *lock) 2583 { 2584 2585 witness_setflag(lock, LI_NORELEASE, 0); 2586 } 2587 2588 #ifdef DDB 2589 static void 2590 witness_ddb_list(struct thread *td) 2591 { 2592 2593 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); 2594 KASSERT(kdb_active, ("%s: not in the debugger", __func__)); 2595 2596 if (witness_watch < 1) 2597 return; 2598 2599 witness_list_locks(&td->td_sleeplocks, db_printf); 2600 2601 /* 2602 * We only handle spinlocks if td == curthread. This is somewhat broken 2603 * if td is currently executing on some other CPU and holds spin locks 2604 * as we won't display those locks. If we had a MI way of getting 2605 * the per-cpu data for a given cpu then we could use 2606 * td->td_oncpu to get the list of spinlocks for this thread 2607 * and "fix" this. 2608 * 2609 * That still wouldn't really fix this unless we locked the scheduler 2610 * lock or stopped the other CPU to make sure it wasn't changing the 2611 * list out from under us. It is probably best to just not try to 2612 * handle threads on other CPU's for now. 2613 */ 2614 if (td == curthread && PCPU_GET(spinlocks) != NULL) 2615 witness_list_locks(PCPU_PTR(spinlocks), db_printf); 2616 } 2617 2618 DB_SHOW_COMMAND(locks, db_witness_list) 2619 { 2620 struct thread *td; 2621 2622 if (have_addr) 2623 td = db_lookup_thread(addr, true); 2624 else 2625 td = kdb_thread; 2626 witness_ddb_list(td); 2627 } 2628 2629 DB_SHOW_ALL_COMMAND(locks, db_witness_list_all) 2630 { 2631 struct thread *td; 2632 struct proc *p; 2633 2634 /* 2635 * It would be nice to list only threads and processes that actually 2636 * held sleep locks, but that information is currently not exported 2637 * by WITNESS. 2638 */ 2639 FOREACH_PROC_IN_SYSTEM(p) { 2640 if (!witness_proc_has_locks(p)) 2641 continue; 2642 FOREACH_THREAD_IN_PROC(p, td) { 2643 if (!witness_thread_has_locks(td)) 2644 continue; 2645 db_printf("Process %d (%s) thread %p (%d)\n", p->p_pid, 2646 p->p_comm, td, td->td_tid); 2647 witness_ddb_list(td); 2648 if (db_pager_quit) 2649 return; 2650 } 2651 } 2652 } 2653 DB_SHOW_ALIAS_FLAGS(alllocks, db_witness_list_all, DB_CMD_MEMSAFE); 2654 2655 DB_SHOW_COMMAND_FLAGS(witness, db_witness_display, DB_CMD_MEMSAFE) 2656 { 2657 2658 witness_ddb_display(db_printf); 2659 } 2660 #endif 2661 2662 static void 2663 sbuf_print_witness_badstacks(struct sbuf *sb, size_t *oldidx) 2664 { 2665 struct witness_lock_order_data *data1, *data2, *tmp_data1, *tmp_data2; 2666 struct witness *tmp_w1, *tmp_w2, *w1, *w2; 2667 int generation, i, j; 2668 2669 tmp_data1 = NULL; 2670 tmp_data2 = NULL; 2671 tmp_w1 = NULL; 2672 tmp_w2 = NULL; 2673 2674 /* Allocate and init temporary storage space. */ 2675 tmp_w1 = malloc(sizeof(struct witness), M_TEMP, M_WAITOK | M_ZERO); 2676 tmp_w2 = malloc(sizeof(struct witness), M_TEMP, M_WAITOK | M_ZERO); 2677 tmp_data1 = malloc(sizeof(struct witness_lock_order_data), M_TEMP, 2678 M_WAITOK | M_ZERO); 2679 tmp_data2 = malloc(sizeof(struct witness_lock_order_data), M_TEMP, 2680 M_WAITOK | M_ZERO); 2681 stack_zero(&tmp_data1->wlod_stack); 2682 stack_zero(&tmp_data2->wlod_stack); 2683 2684 restart: 2685 mtx_lock_spin(&w_mtx); 2686 generation = w_generation; 2687 mtx_unlock_spin(&w_mtx); 2688 sbuf_printf(sb, "Number of known direct relationships is %d\n", 2689 w_lohash.wloh_count); 2690 for (i = 1; i < w_max_used_index; i++) { 2691 mtx_lock_spin(&w_mtx); 2692 if (generation != w_generation) { 2693 mtx_unlock_spin(&w_mtx); 2694 2695 /* The graph has changed, try again. */ 2696 *oldidx = 0; 2697 sbuf_clear(sb); 2698 goto restart; 2699 } 2700 2701 w1 = &w_data[i]; 2702 if (w1->w_reversed == 0) { 2703 mtx_unlock_spin(&w_mtx); 2704 continue; 2705 } 2706 2707 /* Copy w1 locally so we can release the spin lock. */ 2708 *tmp_w1 = *w1; 2709 mtx_unlock_spin(&w_mtx); 2710 2711 if (tmp_w1->w_reversed == 0) 2712 continue; 2713 for (j = 1; j < w_max_used_index; j++) { 2714 if ((w_rmatrix[i][j] & WITNESS_REVERSAL) == 0 || i > j) 2715 continue; 2716 2717 mtx_lock_spin(&w_mtx); 2718 if (generation != w_generation) { 2719 mtx_unlock_spin(&w_mtx); 2720 2721 /* The graph has changed, try again. */ 2722 *oldidx = 0; 2723 sbuf_clear(sb); 2724 goto restart; 2725 } 2726 2727 w2 = &w_data[j]; 2728 data1 = witness_lock_order_get(w1, w2); 2729 data2 = witness_lock_order_get(w2, w1); 2730 2731 /* 2732 * Copy information locally so we can release the 2733 * spin lock. 2734 */ 2735 *tmp_w2 = *w2; 2736 2737 if (data1) { 2738 stack_zero(&tmp_data1->wlod_stack); 2739 stack_copy(&data1->wlod_stack, 2740 &tmp_data1->wlod_stack); 2741 } 2742 if (data2 && data2 != data1) { 2743 stack_zero(&tmp_data2->wlod_stack); 2744 stack_copy(&data2->wlod_stack, 2745 &tmp_data2->wlod_stack); 2746 } 2747 mtx_unlock_spin(&w_mtx); 2748 2749 if (blessed(tmp_w1, tmp_w2)) 2750 continue; 2751 2752 sbuf_printf(sb, 2753 "\nLock order reversal between \"%s\"(%s) and \"%s\"(%s)!\n", 2754 tmp_w1->w_name, tmp_w1->w_class->lc_name, 2755 tmp_w2->w_name, tmp_w2->w_class->lc_name); 2756 if (data1) { 2757 sbuf_printf(sb, 2758 "Lock order \"%s\"(%s) -> \"%s\"(%s) first seen at:\n", 2759 tmp_w1->w_name, tmp_w1->w_class->lc_name, 2760 tmp_w2->w_name, tmp_w2->w_class->lc_name); 2761 stack_sbuf_print(sb, &tmp_data1->wlod_stack); 2762 sbuf_putc(sb, '\n'); 2763 } 2764 if (data2 && data2 != data1) { 2765 sbuf_printf(sb, 2766 "Lock order \"%s\"(%s) -> \"%s\"(%s) first seen at:\n", 2767 tmp_w2->w_name, tmp_w2->w_class->lc_name, 2768 tmp_w1->w_name, tmp_w1->w_class->lc_name); 2769 stack_sbuf_print(sb, &tmp_data2->wlod_stack); 2770 sbuf_putc(sb, '\n'); 2771 } 2772 } 2773 } 2774 mtx_lock_spin(&w_mtx); 2775 if (generation != w_generation) { 2776 mtx_unlock_spin(&w_mtx); 2777 2778 /* 2779 * The graph changed while we were printing stack data, 2780 * try again. 2781 */ 2782 *oldidx = 0; 2783 sbuf_clear(sb); 2784 goto restart; 2785 } 2786 mtx_unlock_spin(&w_mtx); 2787 2788 /* Free temporary storage space. */ 2789 free(tmp_data1, M_TEMP); 2790 free(tmp_data2, M_TEMP); 2791 free(tmp_w1, M_TEMP); 2792 free(tmp_w2, M_TEMP); 2793 } 2794 2795 static int 2796 sysctl_debug_witness_badstacks(SYSCTL_HANDLER_ARGS) 2797 { 2798 struct sbuf *sb; 2799 int error; 2800 2801 if (witness_watch < 1) { 2802 error = SYSCTL_OUT(req, w_notrunning, sizeof(w_notrunning)); 2803 return (error); 2804 } 2805 if (witness_cold) { 2806 error = SYSCTL_OUT(req, w_stillcold, sizeof(w_stillcold)); 2807 return (error); 2808 } 2809 error = 0; 2810 sb = sbuf_new(NULL, NULL, badstack_sbuf_size, SBUF_AUTOEXTEND); 2811 if (sb == NULL) 2812 return (ENOMEM); 2813 2814 sbuf_print_witness_badstacks(sb, &req->oldidx); 2815 2816 sbuf_finish(sb); 2817 error = SYSCTL_OUT(req, sbuf_data(sb), sbuf_len(sb) + 1); 2818 sbuf_delete(sb); 2819 2820 return (error); 2821 } 2822 2823 #ifdef DDB 2824 static int 2825 sbuf_db_printf_drain(void *arg __unused, const char *data, int len) 2826 { 2827 2828 return (db_printf("%.*s", len, data)); 2829 } 2830 2831 DB_SHOW_COMMAND_FLAGS(badstacks, db_witness_badstacks, DB_CMD_MEMSAFE) 2832 { 2833 struct sbuf sb; 2834 char buffer[128]; 2835 size_t dummy; 2836 2837 sbuf_new(&sb, buffer, sizeof(buffer), SBUF_FIXEDLEN); 2838 sbuf_set_drain(&sb, sbuf_db_printf_drain, NULL); 2839 sbuf_print_witness_badstacks(&sb, &dummy); 2840 sbuf_finish(&sb); 2841 } 2842 #endif 2843 2844 static int 2845 sysctl_debug_witness_channel(SYSCTL_HANDLER_ARGS) 2846 { 2847 static const struct { 2848 enum witness_channel channel; 2849 const char *name; 2850 } channels[] = { 2851 { WITNESS_CONSOLE, "console" }, 2852 { WITNESS_LOG, "log" }, 2853 { WITNESS_NONE, "none" }, 2854 }; 2855 char buf[16]; 2856 u_int i; 2857 int error; 2858 2859 buf[0] = '\0'; 2860 for (i = 0; i < nitems(channels); i++) 2861 if (witness_channel == channels[i].channel) { 2862 snprintf(buf, sizeof(buf), "%s", channels[i].name); 2863 break; 2864 } 2865 2866 error = sysctl_handle_string(oidp, buf, sizeof(buf), req); 2867 if (error != 0 || req->newptr == NULL) 2868 return (error); 2869 2870 error = EINVAL; 2871 for (i = 0; i < nitems(channels); i++) 2872 if (strcmp(channels[i].name, buf) == 0) { 2873 witness_channel = channels[i].channel; 2874 error = 0; 2875 break; 2876 } 2877 return (error); 2878 } 2879 2880 static int 2881 sysctl_debug_witness_fullgraph(SYSCTL_HANDLER_ARGS) 2882 { 2883 struct witness *w; 2884 struct sbuf *sb; 2885 int error; 2886 2887 #ifdef __i386__ 2888 error = SYSCTL_OUT(req, w_notallowed, sizeof(w_notallowed)); 2889 return (error); 2890 #endif 2891 2892 if (witness_watch < 1) { 2893 error = SYSCTL_OUT(req, w_notrunning, sizeof(w_notrunning)); 2894 return (error); 2895 } 2896 if (witness_cold) { 2897 error = SYSCTL_OUT(req, w_stillcold, sizeof(w_stillcold)); 2898 return (error); 2899 } 2900 error = 0; 2901 2902 error = sysctl_wire_old_buffer(req, 0); 2903 if (error != 0) 2904 return (error); 2905 sb = sbuf_new_for_sysctl(NULL, NULL, FULLGRAPH_SBUF_SIZE, req); 2906 if (sb == NULL) 2907 return (ENOMEM); 2908 sbuf_putc(sb, '\n'); 2909 2910 mtx_lock_spin(&w_mtx); 2911 STAILQ_FOREACH(w, &w_all, w_list) 2912 w->w_displayed = 0; 2913 STAILQ_FOREACH(w, &w_all, w_list) 2914 witness_add_fullgraph(sb, w); 2915 mtx_unlock_spin(&w_mtx); 2916 2917 /* 2918 * Close the sbuf and return to userland. 2919 */ 2920 error = sbuf_finish(sb); 2921 sbuf_delete(sb); 2922 2923 return (error); 2924 } 2925 2926 static int 2927 sysctl_debug_witness_watch(SYSCTL_HANDLER_ARGS) 2928 { 2929 int error, value; 2930 2931 value = witness_watch; 2932 error = sysctl_handle_int(oidp, &value, 0, req); 2933 if (error != 0 || req->newptr == NULL) 2934 return (error); 2935 if (value > 1 || value < -1 || 2936 (witness_watch == -1 && value != witness_watch)) 2937 return (EINVAL); 2938 witness_watch = value; 2939 return (0); 2940 } 2941 2942 static void 2943 witness_add_fullgraph(struct sbuf *sb, struct witness *w) 2944 { 2945 int i; 2946 2947 if (w->w_displayed != 0 || (w->w_file == NULL && w->w_line == 0)) 2948 return; 2949 w->w_displayed = 1; 2950 2951 WITNESS_INDEX_ASSERT(w->w_index); 2952 for (i = 1; i <= w_max_used_index; i++) { 2953 if (w_rmatrix[w->w_index][i] & WITNESS_PARENT) { 2954 sbuf_printf(sb, "\"%s\",\"%s\"\n", w->w_name, 2955 w_data[i].w_name); 2956 witness_add_fullgraph(sb, &w_data[i]); 2957 } 2958 } 2959 } 2960 2961 /* 2962 * A simple hash function. Takes a key pointer and a key size. If size == 0, 2963 * interprets the key as a string and reads until the null 2964 * terminator. Otherwise, reads the first size bytes. Returns an unsigned 32-bit 2965 * hash value computed from the key. 2966 */ 2967 static uint32_t 2968 witness_hash_djb2(const uint8_t *key, uint32_t size) 2969 { 2970 unsigned int hash = 5381; 2971 int i; 2972 2973 /* hash = hash * 33 + key[i] */ 2974 if (size) 2975 for (i = 0; i < size; i++) 2976 hash = ((hash << 5) + hash) + (unsigned int)key[i]; 2977 else 2978 for (i = 0; key[i] != 0; i++) 2979 hash = ((hash << 5) + hash) + (unsigned int)key[i]; 2980 2981 return (hash); 2982 } 2983 2984 /* 2985 * Initializes the two witness hash tables. Called exactly once from 2986 * witness_initialize(). 2987 */ 2988 static void 2989 witness_init_hash_tables(void) 2990 { 2991 int i; 2992 2993 MPASS(witness_cold); 2994 2995 /* Initialize the hash tables. */ 2996 for (i = 0; i < WITNESS_HASH_SIZE; i++) 2997 w_hash.wh_array[i] = NULL; 2998 2999 w_hash.wh_size = WITNESS_HASH_SIZE; 3000 w_hash.wh_count = 0; 3001 3002 /* Initialize the lock order data hash. */ 3003 w_lofree = NULL; 3004 for (i = 0; i < WITNESS_LO_DATA_COUNT; i++) { 3005 memset(&w_lodata[i], 0, sizeof(w_lodata[i])); 3006 w_lodata[i].wlod_next = w_lofree; 3007 w_lofree = &w_lodata[i]; 3008 } 3009 w_lohash.wloh_size = WITNESS_LO_HASH_SIZE; 3010 w_lohash.wloh_count = 0; 3011 for (i = 0; i < WITNESS_LO_HASH_SIZE; i++) 3012 w_lohash.wloh_array[i] = NULL; 3013 } 3014 3015 static struct witness * 3016 witness_hash_get(const char *key) 3017 { 3018 struct witness *w; 3019 uint32_t hash; 3020 3021 MPASS(key != NULL); 3022 if (witness_cold == 0) 3023 mtx_assert(&w_mtx, MA_OWNED); 3024 hash = witness_hash_djb2(key, 0) % w_hash.wh_size; 3025 w = w_hash.wh_array[hash]; 3026 while (w != NULL) { 3027 if (strcmp(w->w_name, key) == 0) 3028 goto out; 3029 w = w->w_hash_next; 3030 } 3031 3032 out: 3033 return (w); 3034 } 3035 3036 static void 3037 witness_hash_put(struct witness *w) 3038 { 3039 uint32_t hash; 3040 3041 MPASS(w != NULL); 3042 MPASS(w->w_name != NULL); 3043 if (witness_cold == 0) 3044 mtx_assert(&w_mtx, MA_OWNED); 3045 KASSERT(witness_hash_get(w->w_name) == NULL, 3046 ("%s: trying to add a hash entry that already exists!", __func__)); 3047 KASSERT(w->w_hash_next == NULL, 3048 ("%s: w->w_hash_next != NULL", __func__)); 3049 3050 hash = witness_hash_djb2(w->w_name, 0) % w_hash.wh_size; 3051 w->w_hash_next = w_hash.wh_array[hash]; 3052 w_hash.wh_array[hash] = w; 3053 w_hash.wh_count++; 3054 } 3055 3056 static struct witness_lock_order_data * 3057 witness_lock_order_get(struct witness *parent, struct witness *child) 3058 { 3059 struct witness_lock_order_data *data = NULL; 3060 struct witness_lock_order_key key; 3061 unsigned int hash; 3062 3063 MPASS(parent != NULL && child != NULL); 3064 key.from = parent->w_index; 3065 key.to = child->w_index; 3066 WITNESS_INDEX_ASSERT(key.from); 3067 WITNESS_INDEX_ASSERT(key.to); 3068 if ((w_rmatrix[parent->w_index][child->w_index] 3069 & WITNESS_LOCK_ORDER_KNOWN) == 0) 3070 goto out; 3071 3072 hash = witness_hash_djb2((const char*)&key, 3073 sizeof(key)) % w_lohash.wloh_size; 3074 data = w_lohash.wloh_array[hash]; 3075 while (data != NULL) { 3076 if (witness_lock_order_key_equal(&data->wlod_key, &key)) 3077 break; 3078 data = data->wlod_next; 3079 } 3080 3081 out: 3082 return (data); 3083 } 3084 3085 /* 3086 * Verify that parent and child have a known relationship, are not the same, 3087 * and child is actually a child of parent. This is done without w_mtx 3088 * to avoid contention in the common case. 3089 */ 3090 static int 3091 witness_lock_order_check(struct witness *parent, struct witness *child) 3092 { 3093 3094 if (parent != child && 3095 w_rmatrix[parent->w_index][child->w_index] 3096 & WITNESS_LOCK_ORDER_KNOWN && 3097 isitmychild(parent, child)) 3098 return (1); 3099 3100 return (0); 3101 } 3102 3103 static int 3104 witness_lock_order_add(struct witness *parent, struct witness *child) 3105 { 3106 struct witness_lock_order_data *data = NULL; 3107 struct witness_lock_order_key key; 3108 unsigned int hash; 3109 3110 MPASS(parent != NULL && child != NULL); 3111 key.from = parent->w_index; 3112 key.to = child->w_index; 3113 WITNESS_INDEX_ASSERT(key.from); 3114 WITNESS_INDEX_ASSERT(key.to); 3115 if (w_rmatrix[parent->w_index][child->w_index] 3116 & WITNESS_LOCK_ORDER_KNOWN) 3117 return (1); 3118 3119 hash = witness_hash_djb2((const char*)&key, 3120 sizeof(key)) % w_lohash.wloh_size; 3121 w_rmatrix[parent->w_index][child->w_index] |= WITNESS_LOCK_ORDER_KNOWN; 3122 data = w_lofree; 3123 if (data == NULL) 3124 return (0); 3125 w_lofree = data->wlod_next; 3126 data->wlod_next = w_lohash.wloh_array[hash]; 3127 data->wlod_key = key; 3128 w_lohash.wloh_array[hash] = data; 3129 w_lohash.wloh_count++; 3130 stack_save(&data->wlod_stack); 3131 return (1); 3132 } 3133 3134 /* Call this whenever the structure of the witness graph changes. */ 3135 static void 3136 witness_increment_graph_generation(void) 3137 { 3138 3139 if (witness_cold == 0) 3140 mtx_assert(&w_mtx, MA_OWNED); 3141 w_generation++; 3142 } 3143 3144 static int 3145 witness_output_drain(void *arg __unused, const char *data, int len) 3146 { 3147 3148 witness_output("%.*s", len, data); 3149 return (len); 3150 } 3151 3152 static void 3153 witness_debugger(int cond, const char *msg) 3154 { 3155 char buf[32]; 3156 struct sbuf sb; 3157 struct stack st; 3158 3159 if (!cond) 3160 return; 3161 3162 if (witness_trace) { 3163 sbuf_new(&sb, buf, sizeof(buf), SBUF_FIXEDLEN); 3164 sbuf_set_drain(&sb, witness_output_drain, NULL); 3165 3166 stack_save(&st); 3167 witness_output("stack backtrace:\n"); 3168 stack_sbuf_print_ddb(&sb, &st); 3169 3170 sbuf_finish(&sb); 3171 } 3172 3173 witness_enter_debugger(msg); 3174 } 3175 3176 static void 3177 witness_enter_debugger(const char *msg) 3178 { 3179 #ifdef KDB 3180 if (witness_kdb) 3181 kdb_enter(KDB_WHY_WITNESS, msg); 3182 #endif 3183 } 3184