1 /*- 2 * SPDX-License-Identifier: BSD-3-Clause 3 * 4 * Copyright (c) 2008 Isilon Systems, Inc. 5 * Copyright (c) 2008 Ilya Maykov <ivmaykov@gmail.com> 6 * Copyright (c) 1998 Berkeley Software Design, Inc. 7 * All rights reserved. 8 * 9 * Redistribution and use in source and binary forms, with or without 10 * modification, are permitted provided that the following conditions 11 * are met: 12 * 1. Redistributions of source code must retain the above copyright 13 * notice, this list of conditions and the following disclaimer. 14 * 2. Redistributions in binary form must reproduce the above copyright 15 * notice, this list of conditions and the following disclaimer in the 16 * documentation and/or other materials provided with the distribution. 17 * 3. Berkeley Software Design Inc's name may not be used to endorse or 18 * promote products derived from this software without specific prior 19 * written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY BERKELEY SOFTWARE DESIGN INC ``AS IS'' AND 22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24 * ARE DISCLAIMED. IN NO EVENT SHALL BERKELEY SOFTWARE DESIGN INC BE LIABLE 25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31 * SUCH DAMAGE. 32 * 33 * from BSDI $Id: mutex_witness.c,v 1.1.2.20 2000/04/27 03:10:27 cp Exp $ 34 * and BSDI $Id: synch_machdep.c,v 2.3.2.39 2000/04/27 03:10:25 cp Exp $ 35 */ 36 37 /* 38 * Implementation of the `witness' lock verifier. Originally implemented for 39 * mutexes in BSD/OS. Extended to handle generic lock objects and lock 40 * classes in FreeBSD. 41 */ 42 43 /* 44 * Main Entry: witness 45 * Pronunciation: 'wit-n&s 46 * Function: noun 47 * Etymology: Middle English witnesse, from Old English witnes knowledge, 48 * testimony, witness, from 2wit 49 * Date: before 12th century 50 * 1 : attestation of a fact or event : TESTIMONY 51 * 2 : one that gives evidence; specifically : one who testifies in 52 * a cause or before a judicial tribunal 53 * 3 : one asked to be present at a transaction so as to be able to 54 * testify to its having taken place 55 * 4 : one who has personal knowledge of something 56 * 5 a : something serving as evidence or proof : SIGN 57 * b : public affirmation by word or example of usually 58 * religious faith or conviction <the heroic witness to divine 59 * life -- Pilot> 60 * 6 capitalized : a member of the Jehovah's Witnesses 61 */ 62 63 /* 64 * Special rules concerning Giant and lock orders: 65 * 66 * 1) Giant must be acquired before any other mutexes. Stated another way, 67 * no other mutex may be held when Giant is acquired. 68 * 69 * 2) Giant must be released when blocking on a sleepable lock. 70 * 71 * This rule is less obvious, but is a result of Giant providing the same 72 * semantics as spl(). Basically, when a thread sleeps, it must release 73 * Giant. When a thread blocks on a sleepable lock, it sleeps. Hence rule 74 * 2). 75 * 76 * 3) Giant may be acquired before or after sleepable locks. 77 * 78 * This rule is also not quite as obvious. Giant may be acquired after 79 * a sleepable lock because it is a non-sleepable lock and non-sleepable 80 * locks may always be acquired while holding a sleepable lock. The second 81 * case, Giant before a sleepable lock, follows from rule 2) above. Suppose 82 * you have two threads T1 and T2 and a sleepable lock X. Suppose that T1 83 * acquires X and blocks on Giant. Then suppose that T2 acquires Giant and 84 * blocks on X. When T2 blocks on X, T2 will release Giant allowing T1 to 85 * execute. Thus, acquiring Giant both before and after a sleepable lock 86 * will not result in a lock order reversal. 87 */ 88 89 #include <sys/cdefs.h> 90 __FBSDID("$FreeBSD$"); 91 92 #include "opt_ddb.h" 93 #include "opt_hwpmc_hooks.h" 94 #include "opt_stack.h" 95 #include "opt_witness.h" 96 97 #include <sys/param.h> 98 #include <sys/bus.h> 99 #include <sys/kdb.h> 100 #include <sys/kernel.h> 101 #include <sys/ktr.h> 102 #include <sys/lock.h> 103 #include <sys/malloc.h> 104 #include <sys/mutex.h> 105 #include <sys/priv.h> 106 #include <sys/proc.h> 107 #include <sys/sbuf.h> 108 #include <sys/sched.h> 109 #include <sys/stack.h> 110 #include <sys/sysctl.h> 111 #include <sys/syslog.h> 112 #include <sys/systm.h> 113 114 #ifdef DDB 115 #include <ddb/ddb.h> 116 #endif 117 118 #include <machine/stdarg.h> 119 120 #if !defined(DDB) && !defined(STACK) 121 #error "DDB or STACK options are required for WITNESS" 122 #endif 123 124 /* Note that these traces do not work with KTR_ALQ. */ 125 #if 0 126 #define KTR_WITNESS KTR_SUBSYS 127 #else 128 #define KTR_WITNESS 0 129 #endif 130 131 #define LI_RECURSEMASK 0x0000ffff /* Recursion depth of lock instance. */ 132 #define LI_EXCLUSIVE 0x00010000 /* Exclusive lock instance. */ 133 #define LI_NORELEASE 0x00020000 /* Lock not allowed to be released. */ 134 #define LI_SLEEPABLE 0x00040000 /* Lock may be held while sleeping. */ 135 136 #ifndef WITNESS_COUNT 137 #define WITNESS_COUNT 1536 138 #endif 139 #define WITNESS_HASH_SIZE 251 /* Prime, gives load factor < 2 */ 140 #define WITNESS_PENDLIST (512 + (MAXCPU * 4)) 141 142 /* Allocate 256 KB of stack data space */ 143 #define WITNESS_LO_DATA_COUNT 2048 144 145 /* Prime, gives load factor of ~2 at full load */ 146 #define WITNESS_LO_HASH_SIZE 1021 147 148 /* 149 * XXX: This is somewhat bogus, as we assume here that at most 2048 threads 150 * will hold LOCK_NCHILDREN locks. We handle failure ok, and we should 151 * probably be safe for the most part, but it's still a SWAG. 152 */ 153 #define LOCK_NCHILDREN 5 154 #define LOCK_CHILDCOUNT 2048 155 156 #define MAX_W_NAME 64 157 158 #define FULLGRAPH_SBUF_SIZE 512 159 160 /* 161 * These flags go in the witness relationship matrix and describe the 162 * relationship between any two struct witness objects. 163 */ 164 #define WITNESS_UNRELATED 0x00 /* No lock order relation. */ 165 #define WITNESS_PARENT 0x01 /* Parent, aka direct ancestor. */ 166 #define WITNESS_ANCESTOR 0x02 /* Direct or indirect ancestor. */ 167 #define WITNESS_CHILD 0x04 /* Child, aka direct descendant. */ 168 #define WITNESS_DESCENDANT 0x08 /* Direct or indirect descendant. */ 169 #define WITNESS_ANCESTOR_MASK (WITNESS_PARENT | WITNESS_ANCESTOR) 170 #define WITNESS_DESCENDANT_MASK (WITNESS_CHILD | WITNESS_DESCENDANT) 171 #define WITNESS_RELATED_MASK \ 172 (WITNESS_ANCESTOR_MASK | WITNESS_DESCENDANT_MASK) 173 #define WITNESS_REVERSAL 0x10 /* A lock order reversal has been 174 * observed. */ 175 #define WITNESS_RESERVED1 0x20 /* Unused flag, reserved. */ 176 #define WITNESS_RESERVED2 0x40 /* Unused flag, reserved. */ 177 #define WITNESS_LOCK_ORDER_KNOWN 0x80 /* This lock order is known. */ 178 179 /* Descendant to ancestor flags */ 180 #define WITNESS_DTOA(x) (((x) & WITNESS_RELATED_MASK) >> 2) 181 182 /* Ancestor to descendant flags */ 183 #define WITNESS_ATOD(x) (((x) & WITNESS_RELATED_MASK) << 2) 184 185 #define WITNESS_INDEX_ASSERT(i) \ 186 MPASS((i) > 0 && (i) <= w_max_used_index && (i) < witness_count) 187 188 static MALLOC_DEFINE(M_WITNESS, "Witness", "Witness"); 189 190 /* 191 * Lock instances. A lock instance is the data associated with a lock while 192 * it is held by witness. For example, a lock instance will hold the 193 * recursion count of a lock. Lock instances are held in lists. Spin locks 194 * are held in a per-cpu list while sleep locks are held in per-thread list. 195 */ 196 struct lock_instance { 197 struct lock_object *li_lock; 198 const char *li_file; 199 int li_line; 200 u_int li_flags; 201 }; 202 203 /* 204 * A simple list type used to build the list of locks held by a thread 205 * or CPU. We can't simply embed the list in struct lock_object since a 206 * lock may be held by more than one thread if it is a shared lock. Locks 207 * are added to the head of the list, so we fill up each list entry from 208 * "the back" logically. To ease some of the arithmetic, we actually fill 209 * in each list entry the normal way (children[0] then children[1], etc.) but 210 * when we traverse the list we read children[count-1] as the first entry 211 * down to children[0] as the final entry. 212 */ 213 struct lock_list_entry { 214 struct lock_list_entry *ll_next; 215 struct lock_instance ll_children[LOCK_NCHILDREN]; 216 u_int ll_count; 217 }; 218 219 /* 220 * The main witness structure. One of these per named lock type in the system 221 * (for example, "vnode interlock"). 222 */ 223 struct witness { 224 char w_name[MAX_W_NAME]; 225 uint32_t w_index; /* Index in the relationship matrix */ 226 struct lock_class *w_class; 227 STAILQ_ENTRY(witness) w_list; /* List of all witnesses. */ 228 STAILQ_ENTRY(witness) w_typelist; /* Witnesses of a type. */ 229 struct witness *w_hash_next; /* Linked list in hash buckets. */ 230 const char *w_file; /* File where last acquired */ 231 uint32_t w_line; /* Line where last acquired */ 232 uint32_t w_refcount; 233 uint16_t w_num_ancestors; /* direct/indirect 234 * ancestor count */ 235 uint16_t w_num_descendants; /* direct/indirect 236 * descendant count */ 237 int16_t w_ddb_level; 238 unsigned w_displayed:1; 239 unsigned w_reversed:1; 240 }; 241 242 STAILQ_HEAD(witness_list, witness); 243 244 /* 245 * The witness hash table. Keys are witness names (const char *), elements are 246 * witness objects (struct witness *). 247 */ 248 struct witness_hash { 249 struct witness *wh_array[WITNESS_HASH_SIZE]; 250 uint32_t wh_size; 251 uint32_t wh_count; 252 }; 253 254 /* 255 * Key type for the lock order data hash table. 256 */ 257 struct witness_lock_order_key { 258 uint16_t from; 259 uint16_t to; 260 }; 261 262 struct witness_lock_order_data { 263 struct stack wlod_stack; 264 struct witness_lock_order_key wlod_key; 265 struct witness_lock_order_data *wlod_next; 266 }; 267 268 /* 269 * The witness lock order data hash table. Keys are witness index tuples 270 * (struct witness_lock_order_key), elements are lock order data objects 271 * (struct witness_lock_order_data). 272 */ 273 struct witness_lock_order_hash { 274 struct witness_lock_order_data *wloh_array[WITNESS_LO_HASH_SIZE]; 275 u_int wloh_size; 276 u_int wloh_count; 277 }; 278 279 struct witness_blessed { 280 const char *b_lock1; 281 const char *b_lock2; 282 }; 283 284 struct witness_pendhelp { 285 const char *wh_type; 286 struct lock_object *wh_lock; 287 }; 288 289 struct witness_order_list_entry { 290 const char *w_name; 291 struct lock_class *w_class; 292 }; 293 294 /* 295 * Returns 0 if one of the locks is a spin lock and the other is not. 296 * Returns 1 otherwise. 297 */ 298 static __inline int 299 witness_lock_type_equal(struct witness *w1, struct witness *w2) 300 { 301 302 return ((w1->w_class->lc_flags & (LC_SLEEPLOCK | LC_SPINLOCK)) == 303 (w2->w_class->lc_flags & (LC_SLEEPLOCK | LC_SPINLOCK))); 304 } 305 306 static __inline int 307 witness_lock_order_key_equal(const struct witness_lock_order_key *a, 308 const struct witness_lock_order_key *b) 309 { 310 311 return (a->from == b->from && a->to == b->to); 312 } 313 314 static int _isitmyx(struct witness *w1, struct witness *w2, int rmask, 315 const char *fname); 316 static void adopt(struct witness *parent, struct witness *child); 317 static int blessed(struct witness *, struct witness *); 318 static void depart(struct witness *w); 319 static struct witness *enroll(const char *description, 320 struct lock_class *lock_class); 321 static struct lock_instance *find_instance(struct lock_list_entry *list, 322 const struct lock_object *lock); 323 static int isitmychild(struct witness *parent, struct witness *child); 324 static int isitmydescendant(struct witness *parent, struct witness *child); 325 static void itismychild(struct witness *parent, struct witness *child); 326 static int sysctl_debug_witness_badstacks(SYSCTL_HANDLER_ARGS); 327 static int sysctl_debug_witness_watch(SYSCTL_HANDLER_ARGS); 328 static int sysctl_debug_witness_fullgraph(SYSCTL_HANDLER_ARGS); 329 static int sysctl_debug_witness_channel(SYSCTL_HANDLER_ARGS); 330 static void witness_add_fullgraph(struct sbuf *sb, struct witness *parent); 331 #ifdef DDB 332 static void witness_ddb_compute_levels(void); 333 static void witness_ddb_display(int(*)(const char *fmt, ...)); 334 static void witness_ddb_display_descendants(int(*)(const char *fmt, ...), 335 struct witness *, int indent); 336 static void witness_ddb_display_list(int(*prnt)(const char *fmt, ...), 337 struct witness_list *list); 338 static void witness_ddb_level_descendants(struct witness *parent, int l); 339 static void witness_ddb_list(struct thread *td); 340 #endif 341 static void witness_enter_debugger(const char *msg); 342 static void witness_debugger(int cond, const char *msg); 343 static void witness_free(struct witness *m); 344 static struct witness *witness_get(void); 345 static uint32_t witness_hash_djb2(const uint8_t *key, uint32_t size); 346 static struct witness *witness_hash_get(const char *key); 347 static void witness_hash_put(struct witness *w); 348 static void witness_init_hash_tables(void); 349 static void witness_increment_graph_generation(void); 350 static void witness_lock_list_free(struct lock_list_entry *lle); 351 static struct lock_list_entry *witness_lock_list_get(void); 352 static int witness_lock_order_add(struct witness *parent, 353 struct witness *child); 354 static int witness_lock_order_check(struct witness *parent, 355 struct witness *child); 356 static struct witness_lock_order_data *witness_lock_order_get( 357 struct witness *parent, 358 struct witness *child); 359 static void witness_list_lock(struct lock_instance *instance, 360 int (*prnt)(const char *fmt, ...)); 361 static int witness_output(const char *fmt, ...) __printflike(1, 2); 362 static int witness_output_drain(void *arg __unused, const char *data, 363 int len); 364 static int witness_voutput(const char *fmt, va_list ap) __printflike(1, 0); 365 static void witness_setflag(struct lock_object *lock, int flag, int set); 366 367 FEATURE(witness, "kernel has witness(9) support"); 368 369 static SYSCTL_NODE(_debug, OID_AUTO, witness, CTLFLAG_RW | CTLFLAG_MPSAFE, NULL, 370 "Witness Locking"); 371 372 /* 373 * If set to 0, lock order checking is disabled. If set to -1, 374 * witness is completely disabled. Otherwise witness performs full 375 * lock order checking for all locks. At runtime, lock order checking 376 * may be toggled. However, witness cannot be reenabled once it is 377 * completely disabled. 378 */ 379 static int witness_watch = 1; 380 SYSCTL_PROC(_debug_witness, OID_AUTO, watch, 381 CTLFLAG_RWTUN | CTLTYPE_INT | CTLFLAG_MPSAFE, NULL, 0, 382 sysctl_debug_witness_watch, "I", 383 "witness is watching lock operations"); 384 385 #ifdef KDB 386 /* 387 * When KDB is enabled and witness_kdb is 1, it will cause the system 388 * to drop into kdebug() when: 389 * - a lock hierarchy violation occurs 390 * - locks are held when going to sleep. 391 */ 392 #ifdef WITNESS_KDB 393 int witness_kdb = 1; 394 #else 395 int witness_kdb = 0; 396 #endif 397 SYSCTL_INT(_debug_witness, OID_AUTO, kdb, CTLFLAG_RWTUN, &witness_kdb, 0, ""); 398 #endif /* KDB */ 399 400 #if defined(DDB) || defined(KDB) 401 /* 402 * When DDB or KDB is enabled and witness_trace is 1, it will cause the system 403 * to print a stack trace: 404 * - a lock hierarchy violation occurs 405 * - locks are held when going to sleep. 406 */ 407 int witness_trace = 1; 408 SYSCTL_INT(_debug_witness, OID_AUTO, trace, CTLFLAG_RWTUN, &witness_trace, 0, ""); 409 #endif /* DDB || KDB */ 410 411 #ifdef WITNESS_SKIPSPIN 412 int witness_skipspin = 1; 413 #else 414 int witness_skipspin = 0; 415 #endif 416 SYSCTL_INT(_debug_witness, OID_AUTO, skipspin, CTLFLAG_RDTUN, &witness_skipspin, 0, ""); 417 418 int badstack_sbuf_size; 419 420 int witness_count = WITNESS_COUNT; 421 SYSCTL_INT(_debug_witness, OID_AUTO, witness_count, CTLFLAG_RDTUN, 422 &witness_count, 0, ""); 423 424 /* 425 * Output channel for witness messages. By default we print to the console. 426 */ 427 enum witness_channel { 428 WITNESS_CONSOLE, 429 WITNESS_LOG, 430 WITNESS_NONE, 431 }; 432 433 static enum witness_channel witness_channel = WITNESS_CONSOLE; 434 SYSCTL_PROC(_debug_witness, OID_AUTO, output_channel, 435 CTLTYPE_STRING | CTLFLAG_RWTUN | CTLFLAG_MPSAFE, NULL, 0, 436 sysctl_debug_witness_channel, "A", 437 "Output channel for warnings"); 438 439 /* 440 * Call this to print out the relations between locks. 441 */ 442 SYSCTL_PROC(_debug_witness, OID_AUTO, fullgraph, 443 CTLTYPE_STRING | CTLFLAG_RD | CTLFLAG_MPSAFE, NULL, 0, 444 sysctl_debug_witness_fullgraph, "A", 445 "Show locks relation graphs"); 446 447 /* 448 * Call this to print out the witness faulty stacks. 449 */ 450 SYSCTL_PROC(_debug_witness, OID_AUTO, badstacks, 451 CTLTYPE_STRING | CTLFLAG_RD | CTLFLAG_MPSAFE, NULL, 0, 452 sysctl_debug_witness_badstacks, "A", 453 "Show bad witness stacks"); 454 455 static struct mtx w_mtx; 456 457 /* w_list */ 458 static struct witness_list w_free = STAILQ_HEAD_INITIALIZER(w_free); 459 static struct witness_list w_all = STAILQ_HEAD_INITIALIZER(w_all); 460 461 /* w_typelist */ 462 static struct witness_list w_spin = STAILQ_HEAD_INITIALIZER(w_spin); 463 static struct witness_list w_sleep = STAILQ_HEAD_INITIALIZER(w_sleep); 464 465 /* lock list */ 466 static struct lock_list_entry *w_lock_list_free = NULL; 467 static struct witness_pendhelp pending_locks[WITNESS_PENDLIST]; 468 static u_int pending_cnt; 469 470 static int w_free_cnt, w_spin_cnt, w_sleep_cnt; 471 SYSCTL_INT(_debug_witness, OID_AUTO, free_cnt, CTLFLAG_RD, &w_free_cnt, 0, ""); 472 SYSCTL_INT(_debug_witness, OID_AUTO, spin_cnt, CTLFLAG_RD, &w_spin_cnt, 0, ""); 473 SYSCTL_INT(_debug_witness, OID_AUTO, sleep_cnt, CTLFLAG_RD, &w_sleep_cnt, 0, 474 ""); 475 476 static struct witness *w_data; 477 static uint8_t **w_rmatrix; 478 static struct lock_list_entry w_locklistdata[LOCK_CHILDCOUNT]; 479 static struct witness_hash w_hash; /* The witness hash table. */ 480 481 /* The lock order data hash */ 482 static struct witness_lock_order_data w_lodata[WITNESS_LO_DATA_COUNT]; 483 static struct witness_lock_order_data *w_lofree = NULL; 484 static struct witness_lock_order_hash w_lohash; 485 static int w_max_used_index = 0; 486 static unsigned int w_generation = 0; 487 static const char w_notrunning[] = "Witness not running\n"; 488 static const char w_stillcold[] = "Witness is still cold\n"; 489 #ifdef __i386__ 490 static const char w_notallowed[] = "The sysctl is disabled on the arch\n"; 491 #endif 492 493 static struct witness_order_list_entry order_lists[] = { 494 /* 495 * sx locks 496 */ 497 { "proctree", &lock_class_sx }, 498 { "allproc", &lock_class_sx }, 499 { "allprison", &lock_class_sx }, 500 { NULL, NULL }, 501 /* 502 * Various mutexes 503 */ 504 { "Giant", &lock_class_mtx_sleep }, 505 { "pipe mutex", &lock_class_mtx_sleep }, 506 { "sigio lock", &lock_class_mtx_sleep }, 507 { "process group", &lock_class_mtx_sleep }, 508 #ifdef HWPMC_HOOKS 509 { "pmc-sleep", &lock_class_mtx_sleep }, 510 #endif 511 { "process lock", &lock_class_mtx_sleep }, 512 { "session", &lock_class_mtx_sleep }, 513 { "uidinfo hash", &lock_class_rw }, 514 { "time lock", &lock_class_mtx_sleep }, 515 { NULL, NULL }, 516 /* 517 * umtx 518 */ 519 { "umtx lock", &lock_class_mtx_sleep }, 520 { NULL, NULL }, 521 /* 522 * Sockets 523 */ 524 { "accept", &lock_class_mtx_sleep }, 525 { "so_snd", &lock_class_mtx_sleep }, 526 { "so_rcv", &lock_class_mtx_sleep }, 527 { "sellck", &lock_class_mtx_sleep }, 528 { NULL, NULL }, 529 /* 530 * Routing 531 */ 532 { "so_rcv", &lock_class_mtx_sleep }, 533 { "radix node head", &lock_class_rm }, 534 { "ifaddr", &lock_class_mtx_sleep }, 535 { NULL, NULL }, 536 /* 537 * IPv4 multicast: 538 * protocol locks before interface locks, after UDP locks. 539 */ 540 { "in_multi_sx", &lock_class_sx }, 541 { "udpinp", &lock_class_rw }, 542 { "in_multi_list_mtx", &lock_class_mtx_sleep }, 543 { "igmp_mtx", &lock_class_mtx_sleep }, 544 { "ifnet_rw", &lock_class_rw }, 545 { "if_addr_lock", &lock_class_mtx_sleep }, 546 { NULL, NULL }, 547 /* 548 * IPv6 multicast: 549 * protocol locks before interface locks, after UDP locks. 550 */ 551 { "in6_multi_sx", &lock_class_sx }, 552 { "udpinp", &lock_class_rw }, 553 { "in6_multi_list_mtx", &lock_class_mtx_sleep }, 554 { "mld_mtx", &lock_class_mtx_sleep }, 555 { "ifnet_rw", &lock_class_rw }, 556 { "if_addr_lock", &lock_class_mtx_sleep }, 557 { NULL, NULL }, 558 /* 559 * UNIX Domain Sockets 560 */ 561 { "unp_link_rwlock", &lock_class_rw }, 562 { "unp_list_lock", &lock_class_mtx_sleep }, 563 { "unp", &lock_class_mtx_sleep }, 564 { "so_snd", &lock_class_mtx_sleep }, 565 { NULL, NULL }, 566 /* 567 * UDP/IP 568 */ 569 { "udp", &lock_class_mtx_sleep }, 570 { "udpinp", &lock_class_rw }, 571 { "so_snd", &lock_class_mtx_sleep }, 572 { NULL, NULL }, 573 /* 574 * TCP/IP 575 */ 576 { "tcp", &lock_class_mtx_sleep }, 577 { "tcpinp", &lock_class_rw }, 578 { "so_snd", &lock_class_mtx_sleep }, 579 { NULL, NULL }, 580 /* 581 * BPF 582 */ 583 { "bpf global lock", &lock_class_sx }, 584 { "bpf cdev lock", &lock_class_mtx_sleep }, 585 { NULL, NULL }, 586 /* 587 * NFS server 588 */ 589 { "nfsd_mtx", &lock_class_mtx_sleep }, 590 { "so_snd", &lock_class_mtx_sleep }, 591 { NULL, NULL }, 592 593 /* 594 * IEEE 802.11 595 */ 596 { "802.11 com lock", &lock_class_mtx_sleep}, 597 { NULL, NULL }, 598 /* 599 * Network drivers 600 */ 601 { "network driver", &lock_class_mtx_sleep}, 602 { NULL, NULL }, 603 604 /* 605 * Netgraph 606 */ 607 { "ng_node", &lock_class_mtx_sleep }, 608 { "ng_worklist", &lock_class_mtx_sleep }, 609 { NULL, NULL }, 610 /* 611 * CDEV 612 */ 613 { "vm map (system)", &lock_class_mtx_sleep }, 614 { "vnode interlock", &lock_class_mtx_sleep }, 615 { "cdev", &lock_class_mtx_sleep }, 616 { "devthrd", &lock_class_mtx_sleep }, 617 { NULL, NULL }, 618 /* 619 * VM 620 */ 621 { "vm map (user)", &lock_class_sx }, 622 { "vm object", &lock_class_rw }, 623 { "vm page", &lock_class_mtx_sleep }, 624 { "pmap pv global", &lock_class_rw }, 625 { "pmap", &lock_class_mtx_sleep }, 626 { "pmap pv list", &lock_class_rw }, 627 { "vm page free queue", &lock_class_mtx_sleep }, 628 { "vm pagequeue", &lock_class_mtx_sleep }, 629 { NULL, NULL }, 630 /* 631 * kqueue/VFS interaction 632 */ 633 { "kqueue", &lock_class_mtx_sleep }, 634 { "struct mount mtx", &lock_class_mtx_sleep }, 635 { "vnode interlock", &lock_class_mtx_sleep }, 636 { NULL, NULL }, 637 /* 638 * VFS namecache 639 */ 640 { "ncvn", &lock_class_mtx_sleep }, 641 { "ncbuc", &lock_class_mtx_sleep }, 642 { "vnode interlock", &lock_class_mtx_sleep }, 643 { "ncneg", &lock_class_mtx_sleep }, 644 { NULL, NULL }, 645 /* 646 * ZFS locking 647 */ 648 { "dn->dn_mtx", &lock_class_sx }, 649 { "dr->dt.di.dr_mtx", &lock_class_sx }, 650 { "db->db_mtx", &lock_class_sx }, 651 { NULL, NULL }, 652 /* 653 * TCP log locks 654 */ 655 { "TCP ID tree", &lock_class_rw }, 656 { "tcp log id bucket", &lock_class_mtx_sleep }, 657 { "tcpinp", &lock_class_rw }, 658 { "TCP log expireq", &lock_class_mtx_sleep }, 659 { NULL, NULL }, 660 /* 661 * spin locks 662 */ 663 #ifdef SMP 664 { "ap boot", &lock_class_mtx_spin }, 665 #endif 666 { "rm.mutex_mtx", &lock_class_mtx_spin }, 667 #ifdef __i386__ 668 { "cy", &lock_class_mtx_spin }, 669 #endif 670 { "scc_hwmtx", &lock_class_mtx_spin }, 671 { "uart_hwmtx", &lock_class_mtx_spin }, 672 { "fast_taskqueue", &lock_class_mtx_spin }, 673 { "intr table", &lock_class_mtx_spin }, 674 { "process slock", &lock_class_mtx_spin }, 675 { "syscons video lock", &lock_class_mtx_spin }, 676 { "sleepq chain", &lock_class_mtx_spin }, 677 { "rm_spinlock", &lock_class_mtx_spin }, 678 { "turnstile chain", &lock_class_mtx_spin }, 679 { "turnstile lock", &lock_class_mtx_spin }, 680 { "sched lock", &lock_class_mtx_spin }, 681 { "td_contested", &lock_class_mtx_spin }, 682 { "callout", &lock_class_mtx_spin }, 683 { "entropy harvest mutex", &lock_class_mtx_spin }, 684 #ifdef SMP 685 { "smp rendezvous", &lock_class_mtx_spin }, 686 #endif 687 #ifdef __powerpc__ 688 { "tlb0", &lock_class_mtx_spin }, 689 #endif 690 { NULL, NULL }, 691 { "sched lock", &lock_class_mtx_spin }, 692 #ifdef HWPMC_HOOKS 693 { "pmc-per-proc", &lock_class_mtx_spin }, 694 #endif 695 { NULL, NULL }, 696 /* 697 * leaf locks 698 */ 699 { "intrcnt", &lock_class_mtx_spin }, 700 { "icu", &lock_class_mtx_spin }, 701 #ifdef __i386__ 702 { "allpmaps", &lock_class_mtx_spin }, 703 { "descriptor tables", &lock_class_mtx_spin }, 704 #endif 705 { "clk", &lock_class_mtx_spin }, 706 { "cpuset", &lock_class_mtx_spin }, 707 { "mprof lock", &lock_class_mtx_spin }, 708 { "zombie lock", &lock_class_mtx_spin }, 709 { "ALD Queue", &lock_class_mtx_spin }, 710 #if defined(__i386__) || defined(__amd64__) 711 { "pcicfg", &lock_class_mtx_spin }, 712 { "NDIS thread lock", &lock_class_mtx_spin }, 713 #endif 714 { "tw_osl_io_lock", &lock_class_mtx_spin }, 715 { "tw_osl_q_lock", &lock_class_mtx_spin }, 716 { "tw_cl_io_lock", &lock_class_mtx_spin }, 717 { "tw_cl_intr_lock", &lock_class_mtx_spin }, 718 { "tw_cl_gen_lock", &lock_class_mtx_spin }, 719 #ifdef HWPMC_HOOKS 720 { "pmc-leaf", &lock_class_mtx_spin }, 721 #endif 722 { "blocked lock", &lock_class_mtx_spin }, 723 { NULL, NULL }, 724 { NULL, NULL } 725 }; 726 727 /* 728 * Pairs of locks which have been blessed. Witness does not complain about 729 * order problems with blessed lock pairs. Please do not add an entry to the 730 * table without an explanatory comment. 731 */ 732 static struct witness_blessed blessed_list[] = { 733 /* 734 * See the comment in ufs_dirhash.c. Basically, a vnode lock serializes 735 * both lock orders, so a deadlock cannot happen as a result of this 736 * LOR. 737 */ 738 { "dirhash", "bufwait" }, 739 740 /* 741 * A UFS vnode may be locked in vget() while a buffer belonging to the 742 * parent directory vnode is locked. 743 */ 744 { "ufs", "bufwait" }, 745 }; 746 747 /* 748 * This global is set to 0 once it becomes safe to use the witness code. 749 */ 750 static int witness_cold = 1; 751 752 /* 753 * This global is set to 1 once the static lock orders have been enrolled 754 * so that a warning can be issued for any spin locks enrolled later. 755 */ 756 static int witness_spin_warn = 0; 757 758 /* Trim useless garbage from filenames. */ 759 static const char * 760 fixup_filename(const char *file) 761 { 762 763 if (file == NULL) 764 return (NULL); 765 while (strncmp(file, "../", 3) == 0) 766 file += 3; 767 return (file); 768 } 769 770 /* 771 * Calculate the size of early witness structures. 772 */ 773 int 774 witness_startup_count(void) 775 { 776 int sz; 777 778 sz = sizeof(struct witness) * witness_count; 779 sz += sizeof(*w_rmatrix) * (witness_count + 1); 780 sz += sizeof(*w_rmatrix[0]) * (witness_count + 1) * 781 (witness_count + 1); 782 783 return (sz); 784 } 785 786 /* 787 * The WITNESS-enabled diagnostic code. Note that the witness code does 788 * assume that the early boot is single-threaded at least until after this 789 * routine is completed. 790 */ 791 void 792 witness_startup(void *mem) 793 { 794 struct lock_object *lock; 795 struct witness_order_list_entry *order; 796 struct witness *w, *w1; 797 uintptr_t p; 798 int i; 799 800 p = (uintptr_t)mem; 801 w_data = (void *)p; 802 p += sizeof(struct witness) * witness_count; 803 804 w_rmatrix = (void *)p; 805 p += sizeof(*w_rmatrix) * (witness_count + 1); 806 807 for (i = 0; i < witness_count + 1; i++) { 808 w_rmatrix[i] = (void *)p; 809 p += sizeof(*w_rmatrix[i]) * (witness_count + 1); 810 } 811 badstack_sbuf_size = witness_count * 256; 812 813 /* 814 * We have to release Giant before initializing its witness 815 * structure so that WITNESS doesn't get confused. 816 */ 817 mtx_unlock(&Giant); 818 mtx_assert(&Giant, MA_NOTOWNED); 819 820 CTR1(KTR_WITNESS, "%s: initializing witness", __func__); 821 mtx_init(&w_mtx, "witness lock", NULL, MTX_SPIN | MTX_QUIET | 822 MTX_NOWITNESS | MTX_NOPROFILE); 823 for (i = witness_count - 1; i >= 0; i--) { 824 w = &w_data[i]; 825 memset(w, 0, sizeof(*w)); 826 w_data[i].w_index = i; /* Witness index never changes. */ 827 witness_free(w); 828 } 829 KASSERT(STAILQ_FIRST(&w_free)->w_index == 0, 830 ("%s: Invalid list of free witness objects", __func__)); 831 832 /* Witness with index 0 is not used to aid in debugging. */ 833 STAILQ_REMOVE_HEAD(&w_free, w_list); 834 w_free_cnt--; 835 836 for (i = 0; i < witness_count; i++) { 837 memset(w_rmatrix[i], 0, sizeof(*w_rmatrix[i]) * 838 (witness_count + 1)); 839 } 840 841 for (i = 0; i < LOCK_CHILDCOUNT; i++) 842 witness_lock_list_free(&w_locklistdata[i]); 843 witness_init_hash_tables(); 844 845 /* First add in all the specified order lists. */ 846 for (order = order_lists; order->w_name != NULL; order++) { 847 w = enroll(order->w_name, order->w_class); 848 if (w == NULL) 849 continue; 850 w->w_file = "order list"; 851 for (order++; order->w_name != NULL; order++) { 852 w1 = enroll(order->w_name, order->w_class); 853 if (w1 == NULL) 854 continue; 855 w1->w_file = "order list"; 856 itismychild(w, w1); 857 w = w1; 858 } 859 } 860 witness_spin_warn = 1; 861 862 /* Iterate through all locks and add them to witness. */ 863 for (i = 0; pending_locks[i].wh_lock != NULL; i++) { 864 lock = pending_locks[i].wh_lock; 865 KASSERT(lock->lo_flags & LO_WITNESS, 866 ("%s: lock %s is on pending list but not LO_WITNESS", 867 __func__, lock->lo_name)); 868 lock->lo_witness = enroll(pending_locks[i].wh_type, 869 LOCK_CLASS(lock)); 870 } 871 872 /* Mark the witness code as being ready for use. */ 873 witness_cold = 0; 874 875 mtx_lock(&Giant); 876 } 877 878 void 879 witness_init(struct lock_object *lock, const char *type) 880 { 881 struct lock_class *class; 882 883 /* Various sanity checks. */ 884 class = LOCK_CLASS(lock); 885 if ((lock->lo_flags & LO_RECURSABLE) != 0 && 886 (class->lc_flags & LC_RECURSABLE) == 0) 887 kassert_panic("%s: lock (%s) %s can not be recursable", 888 __func__, class->lc_name, lock->lo_name); 889 if ((lock->lo_flags & LO_SLEEPABLE) != 0 && 890 (class->lc_flags & LC_SLEEPABLE) == 0) 891 kassert_panic("%s: lock (%s) %s can not be sleepable", 892 __func__, class->lc_name, lock->lo_name); 893 if ((lock->lo_flags & LO_UPGRADABLE) != 0 && 894 (class->lc_flags & LC_UPGRADABLE) == 0) 895 kassert_panic("%s: lock (%s) %s can not be upgradable", 896 __func__, class->lc_name, lock->lo_name); 897 898 /* 899 * If we shouldn't watch this lock, then just clear lo_witness. 900 * Otherwise, if witness_cold is set, then it is too early to 901 * enroll this lock, so defer it to witness_initialize() by adding 902 * it to the pending_locks list. If it is not too early, then enroll 903 * the lock now. 904 */ 905 if (witness_watch < 1 || KERNEL_PANICKED() || 906 (lock->lo_flags & LO_WITNESS) == 0) 907 lock->lo_witness = NULL; 908 else if (witness_cold) { 909 pending_locks[pending_cnt].wh_lock = lock; 910 pending_locks[pending_cnt++].wh_type = type; 911 if (pending_cnt > WITNESS_PENDLIST) 912 panic("%s: pending locks list is too small, " 913 "increase WITNESS_PENDLIST\n", 914 __func__); 915 } else 916 lock->lo_witness = enroll(type, class); 917 } 918 919 void 920 witness_destroy(struct lock_object *lock) 921 { 922 struct lock_class *class; 923 struct witness *w; 924 925 class = LOCK_CLASS(lock); 926 927 if (witness_cold) 928 panic("lock (%s) %s destroyed while witness_cold", 929 class->lc_name, lock->lo_name); 930 931 /* XXX: need to verify that no one holds the lock */ 932 if ((lock->lo_flags & LO_WITNESS) == 0 || lock->lo_witness == NULL) 933 return; 934 w = lock->lo_witness; 935 936 mtx_lock_spin(&w_mtx); 937 MPASS(w->w_refcount > 0); 938 w->w_refcount--; 939 940 if (w->w_refcount == 0) 941 depart(w); 942 mtx_unlock_spin(&w_mtx); 943 } 944 945 #ifdef DDB 946 static void 947 witness_ddb_compute_levels(void) 948 { 949 struct witness *w; 950 951 /* 952 * First clear all levels. 953 */ 954 STAILQ_FOREACH(w, &w_all, w_list) 955 w->w_ddb_level = -1; 956 957 /* 958 * Look for locks with no parents and level all their descendants. 959 */ 960 STAILQ_FOREACH(w, &w_all, w_list) { 961 /* If the witness has ancestors (is not a root), skip it. */ 962 if (w->w_num_ancestors > 0) 963 continue; 964 witness_ddb_level_descendants(w, 0); 965 } 966 } 967 968 static void 969 witness_ddb_level_descendants(struct witness *w, int l) 970 { 971 int i; 972 973 if (w->w_ddb_level >= l) 974 return; 975 976 w->w_ddb_level = l; 977 l++; 978 979 for (i = 1; i <= w_max_used_index; i++) { 980 if (w_rmatrix[w->w_index][i] & WITNESS_PARENT) 981 witness_ddb_level_descendants(&w_data[i], l); 982 } 983 } 984 985 static void 986 witness_ddb_display_descendants(int(*prnt)(const char *fmt, ...), 987 struct witness *w, int indent) 988 { 989 int i; 990 991 for (i = 0; i < indent; i++) 992 prnt(" "); 993 prnt("%s (type: %s, depth: %d, active refs: %d)", 994 w->w_name, w->w_class->lc_name, 995 w->w_ddb_level, w->w_refcount); 996 if (w->w_displayed) { 997 prnt(" -- (already displayed)\n"); 998 return; 999 } 1000 w->w_displayed = 1; 1001 if (w->w_file != NULL && w->w_line != 0) 1002 prnt(" -- last acquired @ %s:%d\n", fixup_filename(w->w_file), 1003 w->w_line); 1004 else 1005 prnt(" -- never acquired\n"); 1006 indent++; 1007 WITNESS_INDEX_ASSERT(w->w_index); 1008 for (i = 1; i <= w_max_used_index; i++) { 1009 if (db_pager_quit) 1010 return; 1011 if (w_rmatrix[w->w_index][i] & WITNESS_PARENT) 1012 witness_ddb_display_descendants(prnt, &w_data[i], 1013 indent); 1014 } 1015 } 1016 1017 static void 1018 witness_ddb_display_list(int(*prnt)(const char *fmt, ...), 1019 struct witness_list *list) 1020 { 1021 struct witness *w; 1022 1023 STAILQ_FOREACH(w, list, w_typelist) { 1024 if (w->w_file == NULL || w->w_ddb_level > 0) 1025 continue; 1026 1027 /* This lock has no anscestors - display its descendants. */ 1028 witness_ddb_display_descendants(prnt, w, 0); 1029 if (db_pager_quit) 1030 return; 1031 } 1032 } 1033 1034 static void 1035 witness_ddb_display(int(*prnt)(const char *fmt, ...)) 1036 { 1037 struct witness *w; 1038 1039 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); 1040 witness_ddb_compute_levels(); 1041 1042 /* Clear all the displayed flags. */ 1043 STAILQ_FOREACH(w, &w_all, w_list) 1044 w->w_displayed = 0; 1045 1046 /* 1047 * First, handle sleep locks which have been acquired at least 1048 * once. 1049 */ 1050 prnt("Sleep locks:\n"); 1051 witness_ddb_display_list(prnt, &w_sleep); 1052 if (db_pager_quit) 1053 return; 1054 1055 /* 1056 * Now do spin locks which have been acquired at least once. 1057 */ 1058 prnt("\nSpin locks:\n"); 1059 witness_ddb_display_list(prnt, &w_spin); 1060 if (db_pager_quit) 1061 return; 1062 1063 /* 1064 * Finally, any locks which have not been acquired yet. 1065 */ 1066 prnt("\nLocks which were never acquired:\n"); 1067 STAILQ_FOREACH(w, &w_all, w_list) { 1068 if (w->w_file != NULL || w->w_refcount == 0) 1069 continue; 1070 prnt("%s (type: %s, depth: %d)\n", w->w_name, 1071 w->w_class->lc_name, w->w_ddb_level); 1072 if (db_pager_quit) 1073 return; 1074 } 1075 } 1076 #endif /* DDB */ 1077 1078 int 1079 witness_defineorder(struct lock_object *lock1, struct lock_object *lock2) 1080 { 1081 1082 if (witness_watch == -1 || KERNEL_PANICKED()) 1083 return (0); 1084 1085 /* Require locks that witness knows about. */ 1086 if (lock1 == NULL || lock1->lo_witness == NULL || lock2 == NULL || 1087 lock2->lo_witness == NULL) 1088 return (EINVAL); 1089 1090 mtx_assert(&w_mtx, MA_NOTOWNED); 1091 mtx_lock_spin(&w_mtx); 1092 1093 /* 1094 * If we already have either an explicit or implied lock order that 1095 * is the other way around, then return an error. 1096 */ 1097 if (witness_watch && 1098 isitmydescendant(lock2->lo_witness, lock1->lo_witness)) { 1099 mtx_unlock_spin(&w_mtx); 1100 return (EDOOFUS); 1101 } 1102 1103 /* Try to add the new order. */ 1104 CTR3(KTR_WITNESS, "%s: adding %s as a child of %s", __func__, 1105 lock2->lo_witness->w_name, lock1->lo_witness->w_name); 1106 itismychild(lock1->lo_witness, lock2->lo_witness); 1107 mtx_unlock_spin(&w_mtx); 1108 return (0); 1109 } 1110 1111 void 1112 witness_checkorder(struct lock_object *lock, int flags, const char *file, 1113 int line, struct lock_object *interlock) 1114 { 1115 struct lock_list_entry *lock_list, *lle; 1116 struct lock_instance *lock1, *lock2, *plock; 1117 struct lock_class *class, *iclass; 1118 struct witness *w, *w1; 1119 struct thread *td; 1120 int i, j; 1121 1122 if (witness_cold || witness_watch < 1 || lock->lo_witness == NULL || 1123 KERNEL_PANICKED()) 1124 return; 1125 1126 w = lock->lo_witness; 1127 class = LOCK_CLASS(lock); 1128 td = curthread; 1129 1130 if (class->lc_flags & LC_SLEEPLOCK) { 1131 /* 1132 * Since spin locks include a critical section, this check 1133 * implicitly enforces a lock order of all sleep locks before 1134 * all spin locks. 1135 */ 1136 if (td->td_critnest != 0 && !kdb_active) 1137 kassert_panic("acquiring blockable sleep lock with " 1138 "spinlock or critical section held (%s) %s @ %s:%d", 1139 class->lc_name, lock->lo_name, 1140 fixup_filename(file), line); 1141 1142 /* 1143 * If this is the first lock acquired then just return as 1144 * no order checking is needed. 1145 */ 1146 lock_list = td->td_sleeplocks; 1147 if (lock_list == NULL || lock_list->ll_count == 0) 1148 return; 1149 } else { 1150 /* 1151 * If this is the first lock, just return as no order 1152 * checking is needed. Avoid problems with thread 1153 * migration pinning the thread while checking if 1154 * spinlocks are held. If at least one spinlock is held 1155 * the thread is in a safe path and it is allowed to 1156 * unpin it. 1157 */ 1158 sched_pin(); 1159 lock_list = PCPU_GET(spinlocks); 1160 if (lock_list == NULL || lock_list->ll_count == 0) { 1161 sched_unpin(); 1162 return; 1163 } 1164 sched_unpin(); 1165 } 1166 1167 /* 1168 * Check to see if we are recursing on a lock we already own. If 1169 * so, make sure that we don't mismatch exclusive and shared lock 1170 * acquires. 1171 */ 1172 lock1 = find_instance(lock_list, lock); 1173 if (lock1 != NULL) { 1174 if ((lock1->li_flags & LI_EXCLUSIVE) != 0 && 1175 (flags & LOP_EXCLUSIVE) == 0) { 1176 witness_output("shared lock of (%s) %s @ %s:%d\n", 1177 class->lc_name, lock->lo_name, 1178 fixup_filename(file), line); 1179 witness_output("while exclusively locked from %s:%d\n", 1180 fixup_filename(lock1->li_file), lock1->li_line); 1181 kassert_panic("excl->share"); 1182 } 1183 if ((lock1->li_flags & LI_EXCLUSIVE) == 0 && 1184 (flags & LOP_EXCLUSIVE) != 0) { 1185 witness_output("exclusive lock of (%s) %s @ %s:%d\n", 1186 class->lc_name, lock->lo_name, 1187 fixup_filename(file), line); 1188 witness_output("while share locked from %s:%d\n", 1189 fixup_filename(lock1->li_file), lock1->li_line); 1190 kassert_panic("share->excl"); 1191 } 1192 return; 1193 } 1194 1195 /* Warn if the interlock is not locked exactly once. */ 1196 if (interlock != NULL) { 1197 iclass = LOCK_CLASS(interlock); 1198 lock1 = find_instance(lock_list, interlock); 1199 if (lock1 == NULL) 1200 kassert_panic("interlock (%s) %s not locked @ %s:%d", 1201 iclass->lc_name, interlock->lo_name, 1202 fixup_filename(file), line); 1203 else if ((lock1->li_flags & LI_RECURSEMASK) != 0) 1204 kassert_panic("interlock (%s) %s recursed @ %s:%d", 1205 iclass->lc_name, interlock->lo_name, 1206 fixup_filename(file), line); 1207 } 1208 1209 /* 1210 * Find the previously acquired lock, but ignore interlocks. 1211 */ 1212 plock = &lock_list->ll_children[lock_list->ll_count - 1]; 1213 if (interlock != NULL && plock->li_lock == interlock) { 1214 if (lock_list->ll_count > 1) 1215 plock = 1216 &lock_list->ll_children[lock_list->ll_count - 2]; 1217 else { 1218 lle = lock_list->ll_next; 1219 1220 /* 1221 * The interlock is the only lock we hold, so 1222 * simply return. 1223 */ 1224 if (lle == NULL) 1225 return; 1226 plock = &lle->ll_children[lle->ll_count - 1]; 1227 } 1228 } 1229 1230 /* 1231 * Try to perform most checks without a lock. If this succeeds we 1232 * can skip acquiring the lock and return success. Otherwise we redo 1233 * the check with the lock held to handle races with concurrent updates. 1234 */ 1235 w1 = plock->li_lock->lo_witness; 1236 if (witness_lock_order_check(w1, w)) 1237 return; 1238 1239 mtx_lock_spin(&w_mtx); 1240 if (witness_lock_order_check(w1, w)) { 1241 mtx_unlock_spin(&w_mtx); 1242 return; 1243 } 1244 witness_lock_order_add(w1, w); 1245 1246 /* 1247 * Check for duplicate locks of the same type. Note that we only 1248 * have to check for this on the last lock we just acquired. Any 1249 * other cases will be caught as lock order violations. 1250 */ 1251 if (w1 == w) { 1252 i = w->w_index; 1253 if (!(lock->lo_flags & LO_DUPOK) && !(flags & LOP_DUPOK) && 1254 !(w_rmatrix[i][i] & WITNESS_REVERSAL)) { 1255 w_rmatrix[i][i] |= WITNESS_REVERSAL; 1256 w->w_reversed = 1; 1257 mtx_unlock_spin(&w_mtx); 1258 witness_output( 1259 "acquiring duplicate lock of same type: \"%s\"\n", 1260 w->w_name); 1261 witness_output(" 1st %s @ %s:%d\n", plock->li_lock->lo_name, 1262 fixup_filename(plock->li_file), plock->li_line); 1263 witness_output(" 2nd %s @ %s:%d\n", lock->lo_name, 1264 fixup_filename(file), line); 1265 witness_debugger(1, __func__); 1266 } else 1267 mtx_unlock_spin(&w_mtx); 1268 return; 1269 } 1270 mtx_assert(&w_mtx, MA_OWNED); 1271 1272 /* 1273 * If we know that the lock we are acquiring comes after 1274 * the lock we most recently acquired in the lock order tree, 1275 * then there is no need for any further checks. 1276 */ 1277 if (isitmychild(w1, w)) 1278 goto out; 1279 1280 for (j = 0, lle = lock_list; lle != NULL; lle = lle->ll_next) { 1281 for (i = lle->ll_count - 1; i >= 0; i--, j++) { 1282 struct stack pstack; 1283 bool pstackv, trace; 1284 1285 MPASS(j < LOCK_CHILDCOUNT * LOCK_NCHILDREN); 1286 lock1 = &lle->ll_children[i]; 1287 1288 /* 1289 * Ignore the interlock. 1290 */ 1291 if (interlock == lock1->li_lock) 1292 continue; 1293 1294 /* 1295 * If this lock doesn't undergo witness checking, 1296 * then skip it. 1297 */ 1298 w1 = lock1->li_lock->lo_witness; 1299 if (w1 == NULL) { 1300 KASSERT((lock1->li_lock->lo_flags & LO_WITNESS) == 0, 1301 ("lock missing witness structure")); 1302 continue; 1303 } 1304 1305 /* 1306 * If we are locking Giant and this is a sleepable 1307 * lock, then skip it. 1308 */ 1309 if ((lock1->li_flags & LI_SLEEPABLE) != 0 && 1310 lock == &Giant.lock_object) 1311 continue; 1312 1313 /* 1314 * If we are locking a sleepable lock and this lock 1315 * is Giant, then skip it. 1316 */ 1317 if ((lock->lo_flags & LO_SLEEPABLE) != 0 && 1318 (flags & LOP_NOSLEEP) == 0 && 1319 lock1->li_lock == &Giant.lock_object) 1320 continue; 1321 1322 /* 1323 * If we are locking a sleepable lock and this lock 1324 * isn't sleepable, we want to treat it as a lock 1325 * order violation to enfore a general lock order of 1326 * sleepable locks before non-sleepable locks. 1327 */ 1328 if ((lock->lo_flags & LO_SLEEPABLE) != 0 && 1329 (flags & LOP_NOSLEEP) == 0 && 1330 (lock1->li_flags & LI_SLEEPABLE) == 0) 1331 goto reversal; 1332 1333 /* 1334 * If we are locking Giant and this is a non-sleepable 1335 * lock, then treat it as a reversal. 1336 */ 1337 if ((lock1->li_flags & LI_SLEEPABLE) == 0 && 1338 lock == &Giant.lock_object) 1339 goto reversal; 1340 1341 /* 1342 * Check the lock order hierarchy for a reveresal. 1343 */ 1344 if (!isitmydescendant(w, w1)) 1345 continue; 1346 reversal: 1347 1348 /* 1349 * We have a lock order violation, check to see if it 1350 * is allowed or has already been yelled about. 1351 */ 1352 1353 /* Bail if this violation is known */ 1354 if (w_rmatrix[w1->w_index][w->w_index] & WITNESS_REVERSAL) 1355 goto out; 1356 1357 /* Record this as a violation */ 1358 w_rmatrix[w1->w_index][w->w_index] |= WITNESS_REVERSAL; 1359 w_rmatrix[w->w_index][w1->w_index] |= WITNESS_REVERSAL; 1360 w->w_reversed = w1->w_reversed = 1; 1361 witness_increment_graph_generation(); 1362 1363 /* 1364 * If the lock order is blessed, bail before logging 1365 * anything. We don't look for other lock order 1366 * violations though, which may be a bug. 1367 */ 1368 if (blessed(w, w1)) 1369 goto out; 1370 1371 trace = atomic_load_int(&witness_trace); 1372 if (trace) { 1373 struct witness_lock_order_data *data; 1374 1375 pstackv = false; 1376 data = witness_lock_order_get(w, w1); 1377 if (data != NULL) { 1378 stack_copy(&data->wlod_stack, 1379 &pstack); 1380 pstackv = true; 1381 } 1382 } 1383 mtx_unlock_spin(&w_mtx); 1384 1385 #ifdef WITNESS_NO_VNODE 1386 /* 1387 * There are known LORs between VNODE locks. They are 1388 * not an indication of a bug. VNODE locks are flagged 1389 * as such (LO_IS_VNODE) and we don't yell if the LOR 1390 * is between 2 VNODE locks. 1391 */ 1392 if ((lock->lo_flags & LO_IS_VNODE) != 0 && 1393 (lock1->li_lock->lo_flags & LO_IS_VNODE) != 0) 1394 return; 1395 #endif 1396 1397 /* 1398 * Ok, yell about it. 1399 */ 1400 if ((lock->lo_flags & LO_SLEEPABLE) != 0 && 1401 (flags & LOP_NOSLEEP) == 0 && 1402 (lock1->li_flags & LI_SLEEPABLE) == 0) 1403 witness_output( 1404 "lock order reversal: (sleepable after non-sleepable)\n"); 1405 else if ((lock1->li_flags & LI_SLEEPABLE) == 0 1406 && lock == &Giant.lock_object) 1407 witness_output( 1408 "lock order reversal: (Giant after non-sleepable)\n"); 1409 else 1410 witness_output("lock order reversal:\n"); 1411 1412 /* 1413 * Try to locate an earlier lock with 1414 * witness w in our list. 1415 */ 1416 do { 1417 lock2 = &lle->ll_children[i]; 1418 MPASS(lock2->li_lock != NULL); 1419 if (lock2->li_lock->lo_witness == w) 1420 break; 1421 if (i == 0 && lle->ll_next != NULL) { 1422 lle = lle->ll_next; 1423 i = lle->ll_count - 1; 1424 MPASS(i >= 0 && i < LOCK_NCHILDREN); 1425 } else 1426 i--; 1427 } while (i >= 0); 1428 if (i < 0) { 1429 witness_output(" 1st %p %s (%s, %s) @ %s:%d\n", 1430 lock1->li_lock, lock1->li_lock->lo_name, 1431 w1->w_name, w1->w_class->lc_name, 1432 fixup_filename(lock1->li_file), 1433 lock1->li_line); 1434 witness_output(" 2nd %p %s (%s, %s) @ %s:%d\n", 1435 lock, lock->lo_name, w->w_name, 1436 w->w_class->lc_name, fixup_filename(file), 1437 line); 1438 } else { 1439 struct witness *w2 = lock2->li_lock->lo_witness; 1440 1441 witness_output(" 1st %p %s (%s, %s) @ %s:%d\n", 1442 lock2->li_lock, lock2->li_lock->lo_name, 1443 w2->w_name, w2->w_class->lc_name, 1444 fixup_filename(lock2->li_file), 1445 lock2->li_line); 1446 witness_output(" 2nd %p %s (%s, %s) @ %s:%d\n", 1447 lock1->li_lock, lock1->li_lock->lo_name, 1448 w1->w_name, w1->w_class->lc_name, 1449 fixup_filename(lock1->li_file), 1450 lock1->li_line); 1451 witness_output(" 3rd %p %s (%s, %s) @ %s:%d\n", lock, 1452 lock->lo_name, w->w_name, 1453 w->w_class->lc_name, fixup_filename(file), 1454 line); 1455 } 1456 if (trace) { 1457 char buf[64]; 1458 struct sbuf sb; 1459 1460 sbuf_new(&sb, buf, sizeof(buf), SBUF_FIXEDLEN); 1461 sbuf_set_drain(&sb, witness_output_drain, 1462 NULL); 1463 1464 if (pstackv) { 1465 sbuf_printf(&sb, 1466 "lock order %s -> %s established at:\n", 1467 w->w_name, w1->w_name); 1468 stack_sbuf_print_flags(&sb, &pstack, 1469 M_NOWAIT, STACK_SBUF_FMT_LONG); 1470 } 1471 1472 sbuf_printf(&sb, 1473 "lock order %s -> %s attempted at:\n", 1474 w1->w_name, w->w_name); 1475 stack_save(&pstack); 1476 stack_sbuf_print_flags(&sb, &pstack, M_NOWAIT, 1477 STACK_SBUF_FMT_LONG); 1478 1479 sbuf_finish(&sb); 1480 sbuf_delete(&sb); 1481 } 1482 witness_enter_debugger(__func__); 1483 return; 1484 } 1485 } 1486 1487 /* 1488 * If requested, build a new lock order. However, don't build a new 1489 * relationship between a sleepable lock and Giant if it is in the 1490 * wrong direction. The correct lock order is that sleepable locks 1491 * always come before Giant. 1492 */ 1493 if (flags & LOP_NEWORDER && 1494 !(plock->li_lock == &Giant.lock_object && 1495 (lock->lo_flags & LO_SLEEPABLE) != 0 && 1496 (flags & LOP_NOSLEEP) == 0)) { 1497 CTR3(KTR_WITNESS, "%s: adding %s as a child of %s", __func__, 1498 w->w_name, plock->li_lock->lo_witness->w_name); 1499 itismychild(plock->li_lock->lo_witness, w); 1500 } 1501 out: 1502 mtx_unlock_spin(&w_mtx); 1503 } 1504 1505 void 1506 witness_lock(struct lock_object *lock, int flags, const char *file, int line) 1507 { 1508 struct lock_list_entry **lock_list, *lle; 1509 struct lock_instance *instance; 1510 struct witness *w; 1511 struct thread *td; 1512 1513 if (witness_cold || witness_watch == -1 || lock->lo_witness == NULL || 1514 KERNEL_PANICKED()) 1515 return; 1516 w = lock->lo_witness; 1517 td = curthread; 1518 1519 /* Determine lock list for this lock. */ 1520 if (LOCK_CLASS(lock)->lc_flags & LC_SLEEPLOCK) 1521 lock_list = &td->td_sleeplocks; 1522 else 1523 lock_list = PCPU_PTR(spinlocks); 1524 1525 /* Check to see if we are recursing on a lock we already own. */ 1526 instance = find_instance(*lock_list, lock); 1527 if (instance != NULL) { 1528 instance->li_flags++; 1529 CTR4(KTR_WITNESS, "%s: pid %d recursed on %s r=%d", __func__, 1530 td->td_proc->p_pid, lock->lo_name, 1531 instance->li_flags & LI_RECURSEMASK); 1532 instance->li_file = file; 1533 instance->li_line = line; 1534 return; 1535 } 1536 1537 /* Update per-witness last file and line acquire. */ 1538 w->w_file = file; 1539 w->w_line = line; 1540 1541 /* Find the next open lock instance in the list and fill it. */ 1542 lle = *lock_list; 1543 if (lle == NULL || lle->ll_count == LOCK_NCHILDREN) { 1544 lle = witness_lock_list_get(); 1545 if (lle == NULL) 1546 return; 1547 lle->ll_next = *lock_list; 1548 CTR3(KTR_WITNESS, "%s: pid %d added lle %p", __func__, 1549 td->td_proc->p_pid, lle); 1550 *lock_list = lle; 1551 } 1552 instance = &lle->ll_children[lle->ll_count++]; 1553 instance->li_lock = lock; 1554 instance->li_line = line; 1555 instance->li_file = file; 1556 instance->li_flags = 0; 1557 if ((flags & LOP_EXCLUSIVE) != 0) 1558 instance->li_flags |= LI_EXCLUSIVE; 1559 if ((lock->lo_flags & LO_SLEEPABLE) != 0 && (flags & LOP_NOSLEEP) == 0) 1560 instance->li_flags |= LI_SLEEPABLE; 1561 CTR4(KTR_WITNESS, "%s: pid %d added %s as lle[%d]", __func__, 1562 td->td_proc->p_pid, lock->lo_name, lle->ll_count - 1); 1563 } 1564 1565 void 1566 witness_upgrade(struct lock_object *lock, int flags, const char *file, int line) 1567 { 1568 struct lock_instance *instance; 1569 struct lock_class *class; 1570 1571 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); 1572 if (lock->lo_witness == NULL || witness_watch == -1 || KERNEL_PANICKED()) 1573 return; 1574 class = LOCK_CLASS(lock); 1575 if (witness_watch) { 1576 if ((lock->lo_flags & LO_UPGRADABLE) == 0) 1577 kassert_panic( 1578 "upgrade of non-upgradable lock (%s) %s @ %s:%d", 1579 class->lc_name, lock->lo_name, 1580 fixup_filename(file), line); 1581 if ((class->lc_flags & LC_SLEEPLOCK) == 0) 1582 kassert_panic( 1583 "upgrade of non-sleep lock (%s) %s @ %s:%d", 1584 class->lc_name, lock->lo_name, 1585 fixup_filename(file), line); 1586 } 1587 instance = find_instance(curthread->td_sleeplocks, lock); 1588 if (instance == NULL) { 1589 kassert_panic("upgrade of unlocked lock (%s) %s @ %s:%d", 1590 class->lc_name, lock->lo_name, 1591 fixup_filename(file), line); 1592 return; 1593 } 1594 if (witness_watch) { 1595 if ((instance->li_flags & LI_EXCLUSIVE) != 0) 1596 kassert_panic( 1597 "upgrade of exclusive lock (%s) %s @ %s:%d", 1598 class->lc_name, lock->lo_name, 1599 fixup_filename(file), line); 1600 if ((instance->li_flags & LI_RECURSEMASK) != 0) 1601 kassert_panic( 1602 "upgrade of recursed lock (%s) %s r=%d @ %s:%d", 1603 class->lc_name, lock->lo_name, 1604 instance->li_flags & LI_RECURSEMASK, 1605 fixup_filename(file), line); 1606 } 1607 instance->li_flags |= LI_EXCLUSIVE; 1608 } 1609 1610 void 1611 witness_downgrade(struct lock_object *lock, int flags, const char *file, 1612 int line) 1613 { 1614 struct lock_instance *instance; 1615 struct lock_class *class; 1616 1617 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); 1618 if (lock->lo_witness == NULL || witness_watch == -1 || KERNEL_PANICKED()) 1619 return; 1620 class = LOCK_CLASS(lock); 1621 if (witness_watch) { 1622 if ((lock->lo_flags & LO_UPGRADABLE) == 0) 1623 kassert_panic( 1624 "downgrade of non-upgradable lock (%s) %s @ %s:%d", 1625 class->lc_name, lock->lo_name, 1626 fixup_filename(file), line); 1627 if ((class->lc_flags & LC_SLEEPLOCK) == 0) 1628 kassert_panic( 1629 "downgrade of non-sleep lock (%s) %s @ %s:%d", 1630 class->lc_name, lock->lo_name, 1631 fixup_filename(file), line); 1632 } 1633 instance = find_instance(curthread->td_sleeplocks, lock); 1634 if (instance == NULL) { 1635 kassert_panic("downgrade of unlocked lock (%s) %s @ %s:%d", 1636 class->lc_name, lock->lo_name, 1637 fixup_filename(file), line); 1638 return; 1639 } 1640 if (witness_watch) { 1641 if ((instance->li_flags & LI_EXCLUSIVE) == 0) 1642 kassert_panic( 1643 "downgrade of shared lock (%s) %s @ %s:%d", 1644 class->lc_name, lock->lo_name, 1645 fixup_filename(file), line); 1646 if ((instance->li_flags & LI_RECURSEMASK) != 0) 1647 kassert_panic( 1648 "downgrade of recursed lock (%s) %s r=%d @ %s:%d", 1649 class->lc_name, lock->lo_name, 1650 instance->li_flags & LI_RECURSEMASK, 1651 fixup_filename(file), line); 1652 } 1653 instance->li_flags &= ~LI_EXCLUSIVE; 1654 } 1655 1656 void 1657 witness_unlock(struct lock_object *lock, int flags, const char *file, int line) 1658 { 1659 struct lock_list_entry **lock_list, *lle; 1660 struct lock_instance *instance; 1661 struct lock_class *class; 1662 struct thread *td; 1663 register_t s; 1664 int i, j; 1665 1666 if (witness_cold || lock->lo_witness == NULL || KERNEL_PANICKED()) 1667 return; 1668 td = curthread; 1669 class = LOCK_CLASS(lock); 1670 1671 /* Find lock instance associated with this lock. */ 1672 if (class->lc_flags & LC_SLEEPLOCK) 1673 lock_list = &td->td_sleeplocks; 1674 else 1675 lock_list = PCPU_PTR(spinlocks); 1676 lle = *lock_list; 1677 for (; *lock_list != NULL; lock_list = &(*lock_list)->ll_next) 1678 for (i = 0; i < (*lock_list)->ll_count; i++) { 1679 instance = &(*lock_list)->ll_children[i]; 1680 if (instance->li_lock == lock) 1681 goto found; 1682 } 1683 1684 /* 1685 * When disabling WITNESS through witness_watch we could end up in 1686 * having registered locks in the td_sleeplocks queue. 1687 * We have to make sure we flush these queues, so just search for 1688 * eventual register locks and remove them. 1689 */ 1690 if (witness_watch > 0) { 1691 kassert_panic("lock (%s) %s not locked @ %s:%d", class->lc_name, 1692 lock->lo_name, fixup_filename(file), line); 1693 return; 1694 } else { 1695 return; 1696 } 1697 found: 1698 1699 /* First, check for shared/exclusive mismatches. */ 1700 if ((instance->li_flags & LI_EXCLUSIVE) != 0 && witness_watch > 0 && 1701 (flags & LOP_EXCLUSIVE) == 0) { 1702 witness_output("shared unlock of (%s) %s @ %s:%d\n", 1703 class->lc_name, lock->lo_name, fixup_filename(file), line); 1704 witness_output("while exclusively locked from %s:%d\n", 1705 fixup_filename(instance->li_file), instance->li_line); 1706 kassert_panic("excl->ushare"); 1707 } 1708 if ((instance->li_flags & LI_EXCLUSIVE) == 0 && witness_watch > 0 && 1709 (flags & LOP_EXCLUSIVE) != 0) { 1710 witness_output("exclusive unlock of (%s) %s @ %s:%d\n", 1711 class->lc_name, lock->lo_name, fixup_filename(file), line); 1712 witness_output("while share locked from %s:%d\n", 1713 fixup_filename(instance->li_file), 1714 instance->li_line); 1715 kassert_panic("share->uexcl"); 1716 } 1717 /* If we are recursed, unrecurse. */ 1718 if ((instance->li_flags & LI_RECURSEMASK) > 0) { 1719 CTR4(KTR_WITNESS, "%s: pid %d unrecursed on %s r=%d", __func__, 1720 td->td_proc->p_pid, instance->li_lock->lo_name, 1721 instance->li_flags); 1722 instance->li_flags--; 1723 return; 1724 } 1725 /* The lock is now being dropped, check for NORELEASE flag */ 1726 if ((instance->li_flags & LI_NORELEASE) != 0 && witness_watch > 0) { 1727 witness_output("forbidden unlock of (%s) %s @ %s:%d\n", 1728 class->lc_name, lock->lo_name, fixup_filename(file), line); 1729 kassert_panic("lock marked norelease"); 1730 } 1731 1732 /* Otherwise, remove this item from the list. */ 1733 s = intr_disable(); 1734 CTR4(KTR_WITNESS, "%s: pid %d removed %s from lle[%d]", __func__, 1735 td->td_proc->p_pid, instance->li_lock->lo_name, 1736 (*lock_list)->ll_count - 1); 1737 for (j = i; j < (*lock_list)->ll_count - 1; j++) 1738 (*lock_list)->ll_children[j] = 1739 (*lock_list)->ll_children[j + 1]; 1740 (*lock_list)->ll_count--; 1741 intr_restore(s); 1742 1743 /* 1744 * In order to reduce contention on w_mtx, we want to keep always an 1745 * head object into lists so that frequent allocation from the 1746 * free witness pool (and subsequent locking) is avoided. 1747 * In order to maintain the current code simple, when the head 1748 * object is totally unloaded it means also that we do not have 1749 * further objects in the list, so the list ownership needs to be 1750 * hand over to another object if the current head needs to be freed. 1751 */ 1752 if ((*lock_list)->ll_count == 0) { 1753 if (*lock_list == lle) { 1754 if (lle->ll_next == NULL) 1755 return; 1756 } else 1757 lle = *lock_list; 1758 *lock_list = lle->ll_next; 1759 CTR3(KTR_WITNESS, "%s: pid %d removed lle %p", __func__, 1760 td->td_proc->p_pid, lle); 1761 witness_lock_list_free(lle); 1762 } 1763 } 1764 1765 void 1766 witness_thread_exit(struct thread *td) 1767 { 1768 struct lock_list_entry *lle; 1769 int i, n; 1770 1771 lle = td->td_sleeplocks; 1772 if (lle == NULL || KERNEL_PANICKED()) 1773 return; 1774 if (lle->ll_count != 0) { 1775 for (n = 0; lle != NULL; lle = lle->ll_next) 1776 for (i = lle->ll_count - 1; i >= 0; i--) { 1777 if (n == 0) 1778 witness_output( 1779 "Thread %p exiting with the following locks held:\n", td); 1780 n++; 1781 witness_list_lock(&lle->ll_children[i], 1782 witness_output); 1783 1784 } 1785 kassert_panic( 1786 "Thread %p cannot exit while holding sleeplocks\n", td); 1787 } 1788 witness_lock_list_free(lle); 1789 } 1790 1791 /* 1792 * Warn if any locks other than 'lock' are held. Flags can be passed in to 1793 * exempt Giant and sleepable locks from the checks as well. If any 1794 * non-exempt locks are held, then a supplied message is printed to the 1795 * output channel along with a list of the offending locks. If indicated in the 1796 * flags then a failure results in a panic as well. 1797 */ 1798 int 1799 witness_warn(int flags, struct lock_object *lock, const char *fmt, ...) 1800 { 1801 struct lock_list_entry *lock_list, *lle; 1802 struct lock_instance *lock1; 1803 struct thread *td; 1804 va_list ap; 1805 int i, n; 1806 1807 if (witness_cold || witness_watch < 1 || KERNEL_PANICKED()) 1808 return (0); 1809 n = 0; 1810 td = curthread; 1811 for (lle = td->td_sleeplocks; lle != NULL; lle = lle->ll_next) 1812 for (i = lle->ll_count - 1; i >= 0; i--) { 1813 lock1 = &lle->ll_children[i]; 1814 if (lock1->li_lock == lock) 1815 continue; 1816 if (flags & WARN_GIANTOK && 1817 lock1->li_lock == &Giant.lock_object) 1818 continue; 1819 if (flags & WARN_SLEEPOK && 1820 (lock1->li_flags & LI_SLEEPABLE) != 0) 1821 continue; 1822 if (n == 0) { 1823 va_start(ap, fmt); 1824 vprintf(fmt, ap); 1825 va_end(ap); 1826 printf(" with the following %slocks held:\n", 1827 (flags & WARN_SLEEPOK) != 0 ? 1828 "non-sleepable " : ""); 1829 } 1830 n++; 1831 witness_list_lock(lock1, printf); 1832 } 1833 1834 /* 1835 * Pin the thread in order to avoid problems with thread migration. 1836 * Once that all verifies are passed about spinlocks ownership, 1837 * the thread is in a safe path and it can be unpinned. 1838 */ 1839 sched_pin(); 1840 lock_list = PCPU_GET(spinlocks); 1841 if (lock_list != NULL && lock_list->ll_count != 0) { 1842 sched_unpin(); 1843 1844 /* 1845 * We should only have one spinlock and as long as 1846 * the flags cannot match for this locks class, 1847 * check if the first spinlock is the one curthread 1848 * should hold. 1849 */ 1850 lock1 = &lock_list->ll_children[lock_list->ll_count - 1]; 1851 if (lock_list->ll_count == 1 && lock_list->ll_next == NULL && 1852 lock1->li_lock == lock && n == 0) 1853 return (0); 1854 1855 va_start(ap, fmt); 1856 vprintf(fmt, ap); 1857 va_end(ap); 1858 printf(" with the following %slocks held:\n", 1859 (flags & WARN_SLEEPOK) != 0 ? "non-sleepable " : ""); 1860 n += witness_list_locks(&lock_list, printf); 1861 } else 1862 sched_unpin(); 1863 if (flags & WARN_PANIC && n) 1864 kassert_panic("%s", __func__); 1865 else 1866 witness_debugger(n, __func__); 1867 return (n); 1868 } 1869 1870 const char * 1871 witness_file(struct lock_object *lock) 1872 { 1873 struct witness *w; 1874 1875 if (witness_cold || witness_watch < 1 || lock->lo_witness == NULL) 1876 return ("?"); 1877 w = lock->lo_witness; 1878 return (w->w_file); 1879 } 1880 1881 int 1882 witness_line(struct lock_object *lock) 1883 { 1884 struct witness *w; 1885 1886 if (witness_cold || witness_watch < 1 || lock->lo_witness == NULL) 1887 return (0); 1888 w = lock->lo_witness; 1889 return (w->w_line); 1890 } 1891 1892 static struct witness * 1893 enroll(const char *description, struct lock_class *lock_class) 1894 { 1895 struct witness *w; 1896 1897 MPASS(description != NULL); 1898 1899 if (witness_watch == -1 || KERNEL_PANICKED()) 1900 return (NULL); 1901 if ((lock_class->lc_flags & LC_SPINLOCK)) { 1902 if (witness_skipspin) 1903 return (NULL); 1904 } else if ((lock_class->lc_flags & LC_SLEEPLOCK) == 0) { 1905 kassert_panic("lock class %s is not sleep or spin", 1906 lock_class->lc_name); 1907 return (NULL); 1908 } 1909 1910 mtx_lock_spin(&w_mtx); 1911 w = witness_hash_get(description); 1912 if (w) 1913 goto found; 1914 if ((w = witness_get()) == NULL) 1915 return (NULL); 1916 MPASS(strlen(description) < MAX_W_NAME); 1917 strcpy(w->w_name, description); 1918 w->w_class = lock_class; 1919 w->w_refcount = 1; 1920 STAILQ_INSERT_HEAD(&w_all, w, w_list); 1921 if (lock_class->lc_flags & LC_SPINLOCK) { 1922 STAILQ_INSERT_HEAD(&w_spin, w, w_typelist); 1923 w_spin_cnt++; 1924 } else if (lock_class->lc_flags & LC_SLEEPLOCK) { 1925 STAILQ_INSERT_HEAD(&w_sleep, w, w_typelist); 1926 w_sleep_cnt++; 1927 } 1928 1929 /* Insert new witness into the hash */ 1930 witness_hash_put(w); 1931 witness_increment_graph_generation(); 1932 mtx_unlock_spin(&w_mtx); 1933 return (w); 1934 found: 1935 w->w_refcount++; 1936 if (w->w_refcount == 1) 1937 w->w_class = lock_class; 1938 mtx_unlock_spin(&w_mtx); 1939 if (lock_class != w->w_class) 1940 kassert_panic( 1941 "lock (%s) %s does not match earlier (%s) lock", 1942 description, lock_class->lc_name, 1943 w->w_class->lc_name); 1944 return (w); 1945 } 1946 1947 static void 1948 depart(struct witness *w) 1949 { 1950 1951 MPASS(w->w_refcount == 0); 1952 if (w->w_class->lc_flags & LC_SLEEPLOCK) { 1953 w_sleep_cnt--; 1954 } else { 1955 w_spin_cnt--; 1956 } 1957 /* 1958 * Set file to NULL as it may point into a loadable module. 1959 */ 1960 w->w_file = NULL; 1961 w->w_line = 0; 1962 witness_increment_graph_generation(); 1963 } 1964 1965 static void 1966 adopt(struct witness *parent, struct witness *child) 1967 { 1968 int pi, ci, i, j; 1969 1970 if (witness_cold == 0) 1971 mtx_assert(&w_mtx, MA_OWNED); 1972 1973 /* If the relationship is already known, there's no work to be done. */ 1974 if (isitmychild(parent, child)) 1975 return; 1976 1977 /* When the structure of the graph changes, bump up the generation. */ 1978 witness_increment_graph_generation(); 1979 1980 /* 1981 * The hard part ... create the direct relationship, then propagate all 1982 * indirect relationships. 1983 */ 1984 pi = parent->w_index; 1985 ci = child->w_index; 1986 WITNESS_INDEX_ASSERT(pi); 1987 WITNESS_INDEX_ASSERT(ci); 1988 MPASS(pi != ci); 1989 w_rmatrix[pi][ci] |= WITNESS_PARENT; 1990 w_rmatrix[ci][pi] |= WITNESS_CHILD; 1991 1992 /* 1993 * If parent was not already an ancestor of child, 1994 * then we increment the descendant and ancestor counters. 1995 */ 1996 if ((w_rmatrix[pi][ci] & WITNESS_ANCESTOR) == 0) { 1997 parent->w_num_descendants++; 1998 child->w_num_ancestors++; 1999 } 2000 2001 /* 2002 * Find each ancestor of 'pi'. Note that 'pi' itself is counted as 2003 * an ancestor of 'pi' during this loop. 2004 */ 2005 for (i = 1; i <= w_max_used_index; i++) { 2006 if ((w_rmatrix[i][pi] & WITNESS_ANCESTOR_MASK) == 0 && 2007 (i != pi)) 2008 continue; 2009 2010 /* Find each descendant of 'i' and mark it as a descendant. */ 2011 for (j = 1; j <= w_max_used_index; j++) { 2012 /* 2013 * Skip children that are already marked as 2014 * descendants of 'i'. 2015 */ 2016 if (w_rmatrix[i][j] & WITNESS_ANCESTOR_MASK) 2017 continue; 2018 2019 /* 2020 * We are only interested in descendants of 'ci'. Note 2021 * that 'ci' itself is counted as a descendant of 'ci'. 2022 */ 2023 if ((w_rmatrix[ci][j] & WITNESS_ANCESTOR_MASK) == 0 && 2024 (j != ci)) 2025 continue; 2026 w_rmatrix[i][j] |= WITNESS_ANCESTOR; 2027 w_rmatrix[j][i] |= WITNESS_DESCENDANT; 2028 w_data[i].w_num_descendants++; 2029 w_data[j].w_num_ancestors++; 2030 2031 /* 2032 * Make sure we aren't marking a node as both an 2033 * ancestor and descendant. We should have caught 2034 * this as a lock order reversal earlier. 2035 */ 2036 if ((w_rmatrix[i][j] & WITNESS_ANCESTOR_MASK) && 2037 (w_rmatrix[i][j] & WITNESS_DESCENDANT_MASK)) { 2038 printf("witness rmatrix paradox! [%d][%d]=%d " 2039 "both ancestor and descendant\n", 2040 i, j, w_rmatrix[i][j]); 2041 kdb_backtrace(); 2042 printf("Witness disabled.\n"); 2043 witness_watch = -1; 2044 } 2045 if ((w_rmatrix[j][i] & WITNESS_ANCESTOR_MASK) && 2046 (w_rmatrix[j][i] & WITNESS_DESCENDANT_MASK)) { 2047 printf("witness rmatrix paradox! [%d][%d]=%d " 2048 "both ancestor and descendant\n", 2049 j, i, w_rmatrix[j][i]); 2050 kdb_backtrace(); 2051 printf("Witness disabled.\n"); 2052 witness_watch = -1; 2053 } 2054 } 2055 } 2056 } 2057 2058 static void 2059 itismychild(struct witness *parent, struct witness *child) 2060 { 2061 int unlocked; 2062 2063 MPASS(child != NULL && parent != NULL); 2064 if (witness_cold == 0) 2065 mtx_assert(&w_mtx, MA_OWNED); 2066 2067 if (!witness_lock_type_equal(parent, child)) { 2068 if (witness_cold == 0) { 2069 unlocked = 1; 2070 mtx_unlock_spin(&w_mtx); 2071 } else { 2072 unlocked = 0; 2073 } 2074 kassert_panic( 2075 "%s: parent \"%s\" (%s) and child \"%s\" (%s) are not " 2076 "the same lock type", __func__, parent->w_name, 2077 parent->w_class->lc_name, child->w_name, 2078 child->w_class->lc_name); 2079 if (unlocked) 2080 mtx_lock_spin(&w_mtx); 2081 } 2082 adopt(parent, child); 2083 } 2084 2085 /* 2086 * Generic code for the isitmy*() functions. The rmask parameter is the 2087 * expected relationship of w1 to w2. 2088 */ 2089 static int 2090 _isitmyx(struct witness *w1, struct witness *w2, int rmask, const char *fname) 2091 { 2092 unsigned char r1, r2; 2093 int i1, i2; 2094 2095 i1 = w1->w_index; 2096 i2 = w2->w_index; 2097 WITNESS_INDEX_ASSERT(i1); 2098 WITNESS_INDEX_ASSERT(i2); 2099 r1 = w_rmatrix[i1][i2] & WITNESS_RELATED_MASK; 2100 r2 = w_rmatrix[i2][i1] & WITNESS_RELATED_MASK; 2101 2102 /* The flags on one better be the inverse of the flags on the other */ 2103 if (!((WITNESS_ATOD(r1) == r2 && WITNESS_DTOA(r2) == r1) || 2104 (WITNESS_DTOA(r1) == r2 && WITNESS_ATOD(r2) == r1))) { 2105 /* Don't squawk if we're potentially racing with an update. */ 2106 if (!mtx_owned(&w_mtx)) 2107 return (0); 2108 printf("%s: rmatrix mismatch between %s (index %d) and %s " 2109 "(index %d): w_rmatrix[%d][%d] == %hhx but " 2110 "w_rmatrix[%d][%d] == %hhx\n", 2111 fname, w1->w_name, i1, w2->w_name, i2, i1, i2, r1, 2112 i2, i1, r2); 2113 kdb_backtrace(); 2114 printf("Witness disabled.\n"); 2115 witness_watch = -1; 2116 } 2117 return (r1 & rmask); 2118 } 2119 2120 /* 2121 * Checks if @child is a direct child of @parent. 2122 */ 2123 static int 2124 isitmychild(struct witness *parent, struct witness *child) 2125 { 2126 2127 return (_isitmyx(parent, child, WITNESS_PARENT, __func__)); 2128 } 2129 2130 /* 2131 * Checks if @descendant is a direct or inderect descendant of @ancestor. 2132 */ 2133 static int 2134 isitmydescendant(struct witness *ancestor, struct witness *descendant) 2135 { 2136 2137 return (_isitmyx(ancestor, descendant, WITNESS_ANCESTOR_MASK, 2138 __func__)); 2139 } 2140 2141 static int 2142 blessed(struct witness *w1, struct witness *w2) 2143 { 2144 int i; 2145 struct witness_blessed *b; 2146 2147 for (i = 0; i < nitems(blessed_list); i++) { 2148 b = &blessed_list[i]; 2149 if (strcmp(w1->w_name, b->b_lock1) == 0) { 2150 if (strcmp(w2->w_name, b->b_lock2) == 0) 2151 return (1); 2152 continue; 2153 } 2154 if (strcmp(w1->w_name, b->b_lock2) == 0) 2155 if (strcmp(w2->w_name, b->b_lock1) == 0) 2156 return (1); 2157 } 2158 return (0); 2159 } 2160 2161 static struct witness * 2162 witness_get(void) 2163 { 2164 struct witness *w; 2165 int index; 2166 2167 if (witness_cold == 0) 2168 mtx_assert(&w_mtx, MA_OWNED); 2169 2170 if (witness_watch == -1) { 2171 mtx_unlock_spin(&w_mtx); 2172 return (NULL); 2173 } 2174 if (STAILQ_EMPTY(&w_free)) { 2175 witness_watch = -1; 2176 mtx_unlock_spin(&w_mtx); 2177 printf("WITNESS: unable to allocate a new witness object\n"); 2178 return (NULL); 2179 } 2180 w = STAILQ_FIRST(&w_free); 2181 STAILQ_REMOVE_HEAD(&w_free, w_list); 2182 w_free_cnt--; 2183 index = w->w_index; 2184 MPASS(index > 0 && index == w_max_used_index+1 && 2185 index < witness_count); 2186 bzero(w, sizeof(*w)); 2187 w->w_index = index; 2188 if (index > w_max_used_index) 2189 w_max_used_index = index; 2190 return (w); 2191 } 2192 2193 static void 2194 witness_free(struct witness *w) 2195 { 2196 2197 STAILQ_INSERT_HEAD(&w_free, w, w_list); 2198 w_free_cnt++; 2199 } 2200 2201 static struct lock_list_entry * 2202 witness_lock_list_get(void) 2203 { 2204 struct lock_list_entry *lle; 2205 2206 if (witness_watch == -1) 2207 return (NULL); 2208 mtx_lock_spin(&w_mtx); 2209 lle = w_lock_list_free; 2210 if (lle == NULL) { 2211 witness_watch = -1; 2212 mtx_unlock_spin(&w_mtx); 2213 printf("%s: witness exhausted\n", __func__); 2214 return (NULL); 2215 } 2216 w_lock_list_free = lle->ll_next; 2217 mtx_unlock_spin(&w_mtx); 2218 bzero(lle, sizeof(*lle)); 2219 return (lle); 2220 } 2221 2222 static void 2223 witness_lock_list_free(struct lock_list_entry *lle) 2224 { 2225 2226 mtx_lock_spin(&w_mtx); 2227 lle->ll_next = w_lock_list_free; 2228 w_lock_list_free = lle; 2229 mtx_unlock_spin(&w_mtx); 2230 } 2231 2232 static struct lock_instance * 2233 find_instance(struct lock_list_entry *list, const struct lock_object *lock) 2234 { 2235 struct lock_list_entry *lle; 2236 struct lock_instance *instance; 2237 int i; 2238 2239 for (lle = list; lle != NULL; lle = lle->ll_next) 2240 for (i = lle->ll_count - 1; i >= 0; i--) { 2241 instance = &lle->ll_children[i]; 2242 if (instance->li_lock == lock) 2243 return (instance); 2244 } 2245 return (NULL); 2246 } 2247 2248 static void 2249 witness_list_lock(struct lock_instance *instance, 2250 int (*prnt)(const char *fmt, ...)) 2251 { 2252 struct lock_object *lock; 2253 2254 lock = instance->li_lock; 2255 prnt("%s %s %s", (instance->li_flags & LI_EXCLUSIVE) != 0 ? 2256 "exclusive" : "shared", LOCK_CLASS(lock)->lc_name, lock->lo_name); 2257 if (lock->lo_witness->w_name != lock->lo_name) 2258 prnt(" (%s)", lock->lo_witness->w_name); 2259 prnt(" r = %d (%p) locked @ %s:%d\n", 2260 instance->li_flags & LI_RECURSEMASK, lock, 2261 fixup_filename(instance->li_file), instance->li_line); 2262 } 2263 2264 static int 2265 witness_output(const char *fmt, ...) 2266 { 2267 va_list ap; 2268 int ret; 2269 2270 va_start(ap, fmt); 2271 ret = witness_voutput(fmt, ap); 2272 va_end(ap); 2273 return (ret); 2274 } 2275 2276 static int 2277 witness_voutput(const char *fmt, va_list ap) 2278 { 2279 int ret; 2280 2281 ret = 0; 2282 switch (witness_channel) { 2283 case WITNESS_CONSOLE: 2284 ret = vprintf(fmt, ap); 2285 break; 2286 case WITNESS_LOG: 2287 vlog(LOG_NOTICE, fmt, ap); 2288 break; 2289 case WITNESS_NONE: 2290 break; 2291 } 2292 return (ret); 2293 } 2294 2295 #ifdef DDB 2296 static int 2297 witness_thread_has_locks(struct thread *td) 2298 { 2299 2300 if (td->td_sleeplocks == NULL) 2301 return (0); 2302 return (td->td_sleeplocks->ll_count != 0); 2303 } 2304 2305 static int 2306 witness_proc_has_locks(struct proc *p) 2307 { 2308 struct thread *td; 2309 2310 FOREACH_THREAD_IN_PROC(p, td) { 2311 if (witness_thread_has_locks(td)) 2312 return (1); 2313 } 2314 return (0); 2315 } 2316 #endif 2317 2318 int 2319 witness_list_locks(struct lock_list_entry **lock_list, 2320 int (*prnt)(const char *fmt, ...)) 2321 { 2322 struct lock_list_entry *lle; 2323 int i, nheld; 2324 2325 nheld = 0; 2326 for (lle = *lock_list; lle != NULL; lle = lle->ll_next) 2327 for (i = lle->ll_count - 1; i >= 0; i--) { 2328 witness_list_lock(&lle->ll_children[i], prnt); 2329 nheld++; 2330 } 2331 return (nheld); 2332 } 2333 2334 /* 2335 * This is a bit risky at best. We call this function when we have timed 2336 * out acquiring a spin lock, and we assume that the other CPU is stuck 2337 * with this lock held. So, we go groveling around in the other CPU's 2338 * per-cpu data to try to find the lock instance for this spin lock to 2339 * see when it was last acquired. 2340 */ 2341 void 2342 witness_display_spinlock(struct lock_object *lock, struct thread *owner, 2343 int (*prnt)(const char *fmt, ...)) 2344 { 2345 struct lock_instance *instance; 2346 struct pcpu *pc; 2347 2348 if (owner->td_critnest == 0 || owner->td_oncpu == NOCPU) 2349 return; 2350 pc = pcpu_find(owner->td_oncpu); 2351 instance = find_instance(pc->pc_spinlocks, lock); 2352 if (instance != NULL) 2353 witness_list_lock(instance, prnt); 2354 } 2355 2356 void 2357 witness_save(struct lock_object *lock, const char **filep, int *linep) 2358 { 2359 struct lock_list_entry *lock_list; 2360 struct lock_instance *instance; 2361 struct lock_class *class; 2362 2363 /* 2364 * This function is used independently in locking code to deal with 2365 * Giant, SCHEDULER_STOPPED() check can be removed here after Giant 2366 * is gone. 2367 */ 2368 if (SCHEDULER_STOPPED()) 2369 return; 2370 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); 2371 if (lock->lo_witness == NULL || witness_watch == -1 || KERNEL_PANICKED()) 2372 return; 2373 class = LOCK_CLASS(lock); 2374 if (class->lc_flags & LC_SLEEPLOCK) 2375 lock_list = curthread->td_sleeplocks; 2376 else { 2377 if (witness_skipspin) 2378 return; 2379 lock_list = PCPU_GET(spinlocks); 2380 } 2381 instance = find_instance(lock_list, lock); 2382 if (instance == NULL) { 2383 kassert_panic("%s: lock (%s) %s not locked", __func__, 2384 class->lc_name, lock->lo_name); 2385 return; 2386 } 2387 *filep = instance->li_file; 2388 *linep = instance->li_line; 2389 } 2390 2391 void 2392 witness_restore(struct lock_object *lock, const char *file, int line) 2393 { 2394 struct lock_list_entry *lock_list; 2395 struct lock_instance *instance; 2396 struct lock_class *class; 2397 2398 /* 2399 * This function is used independently in locking code to deal with 2400 * Giant, SCHEDULER_STOPPED() check can be removed here after Giant 2401 * is gone. 2402 */ 2403 if (SCHEDULER_STOPPED()) 2404 return; 2405 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); 2406 if (lock->lo_witness == NULL || witness_watch == -1 || KERNEL_PANICKED()) 2407 return; 2408 class = LOCK_CLASS(lock); 2409 if (class->lc_flags & LC_SLEEPLOCK) 2410 lock_list = curthread->td_sleeplocks; 2411 else { 2412 if (witness_skipspin) 2413 return; 2414 lock_list = PCPU_GET(spinlocks); 2415 } 2416 instance = find_instance(lock_list, lock); 2417 if (instance == NULL) 2418 kassert_panic("%s: lock (%s) %s not locked", __func__, 2419 class->lc_name, lock->lo_name); 2420 lock->lo_witness->w_file = file; 2421 lock->lo_witness->w_line = line; 2422 if (instance == NULL) 2423 return; 2424 instance->li_file = file; 2425 instance->li_line = line; 2426 } 2427 2428 void 2429 witness_assert(const struct lock_object *lock, int flags, const char *file, 2430 int line) 2431 { 2432 #ifdef INVARIANT_SUPPORT 2433 struct lock_instance *instance; 2434 struct lock_class *class; 2435 2436 if (lock->lo_witness == NULL || witness_watch < 1 || KERNEL_PANICKED()) 2437 return; 2438 class = LOCK_CLASS(lock); 2439 if ((class->lc_flags & LC_SLEEPLOCK) != 0) 2440 instance = find_instance(curthread->td_sleeplocks, lock); 2441 else if ((class->lc_flags & LC_SPINLOCK) != 0) 2442 instance = find_instance(PCPU_GET(spinlocks), lock); 2443 else { 2444 kassert_panic("Lock (%s) %s is not sleep or spin!", 2445 class->lc_name, lock->lo_name); 2446 return; 2447 } 2448 switch (flags) { 2449 case LA_UNLOCKED: 2450 if (instance != NULL) 2451 kassert_panic("Lock (%s) %s locked @ %s:%d.", 2452 class->lc_name, lock->lo_name, 2453 fixup_filename(file), line); 2454 break; 2455 case LA_LOCKED: 2456 case LA_LOCKED | LA_RECURSED: 2457 case LA_LOCKED | LA_NOTRECURSED: 2458 case LA_SLOCKED: 2459 case LA_SLOCKED | LA_RECURSED: 2460 case LA_SLOCKED | LA_NOTRECURSED: 2461 case LA_XLOCKED: 2462 case LA_XLOCKED | LA_RECURSED: 2463 case LA_XLOCKED | LA_NOTRECURSED: 2464 if (instance == NULL) { 2465 kassert_panic("Lock (%s) %s not locked @ %s:%d.", 2466 class->lc_name, lock->lo_name, 2467 fixup_filename(file), line); 2468 break; 2469 } 2470 if ((flags & LA_XLOCKED) != 0 && 2471 (instance->li_flags & LI_EXCLUSIVE) == 0) 2472 kassert_panic( 2473 "Lock (%s) %s not exclusively locked @ %s:%d.", 2474 class->lc_name, lock->lo_name, 2475 fixup_filename(file), line); 2476 if ((flags & LA_SLOCKED) != 0 && 2477 (instance->li_flags & LI_EXCLUSIVE) != 0) 2478 kassert_panic( 2479 "Lock (%s) %s exclusively locked @ %s:%d.", 2480 class->lc_name, lock->lo_name, 2481 fixup_filename(file), line); 2482 if ((flags & LA_RECURSED) != 0 && 2483 (instance->li_flags & LI_RECURSEMASK) == 0) 2484 kassert_panic("Lock (%s) %s not recursed @ %s:%d.", 2485 class->lc_name, lock->lo_name, 2486 fixup_filename(file), line); 2487 if ((flags & LA_NOTRECURSED) != 0 && 2488 (instance->li_flags & LI_RECURSEMASK) != 0) 2489 kassert_panic("Lock (%s) %s recursed @ %s:%d.", 2490 class->lc_name, lock->lo_name, 2491 fixup_filename(file), line); 2492 break; 2493 default: 2494 kassert_panic("Invalid lock assertion at %s:%d.", 2495 fixup_filename(file), line); 2496 } 2497 #endif /* INVARIANT_SUPPORT */ 2498 } 2499 2500 static void 2501 witness_setflag(struct lock_object *lock, int flag, int set) 2502 { 2503 struct lock_list_entry *lock_list; 2504 struct lock_instance *instance; 2505 struct lock_class *class; 2506 2507 if (lock->lo_witness == NULL || witness_watch == -1 || KERNEL_PANICKED()) 2508 return; 2509 class = LOCK_CLASS(lock); 2510 if (class->lc_flags & LC_SLEEPLOCK) 2511 lock_list = curthread->td_sleeplocks; 2512 else { 2513 if (witness_skipspin) 2514 return; 2515 lock_list = PCPU_GET(spinlocks); 2516 } 2517 instance = find_instance(lock_list, lock); 2518 if (instance == NULL) { 2519 kassert_panic("%s: lock (%s) %s not locked", __func__, 2520 class->lc_name, lock->lo_name); 2521 return; 2522 } 2523 2524 if (set) 2525 instance->li_flags |= flag; 2526 else 2527 instance->li_flags &= ~flag; 2528 } 2529 2530 void 2531 witness_norelease(struct lock_object *lock) 2532 { 2533 2534 witness_setflag(lock, LI_NORELEASE, 1); 2535 } 2536 2537 void 2538 witness_releaseok(struct lock_object *lock) 2539 { 2540 2541 witness_setflag(lock, LI_NORELEASE, 0); 2542 } 2543 2544 #ifdef DDB 2545 static void 2546 witness_ddb_list(struct thread *td) 2547 { 2548 2549 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); 2550 KASSERT(kdb_active, ("%s: not in the debugger", __func__)); 2551 2552 if (witness_watch < 1) 2553 return; 2554 2555 witness_list_locks(&td->td_sleeplocks, db_printf); 2556 2557 /* 2558 * We only handle spinlocks if td == curthread. This is somewhat broken 2559 * if td is currently executing on some other CPU and holds spin locks 2560 * as we won't display those locks. If we had a MI way of getting 2561 * the per-cpu data for a given cpu then we could use 2562 * td->td_oncpu to get the list of spinlocks for this thread 2563 * and "fix" this. 2564 * 2565 * That still wouldn't really fix this unless we locked the scheduler 2566 * lock or stopped the other CPU to make sure it wasn't changing the 2567 * list out from under us. It is probably best to just not try to 2568 * handle threads on other CPU's for now. 2569 */ 2570 if (td == curthread && PCPU_GET(spinlocks) != NULL) 2571 witness_list_locks(PCPU_PTR(spinlocks), db_printf); 2572 } 2573 2574 DB_SHOW_COMMAND(locks, db_witness_list) 2575 { 2576 struct thread *td; 2577 2578 if (have_addr) 2579 td = db_lookup_thread(addr, true); 2580 else 2581 td = kdb_thread; 2582 witness_ddb_list(td); 2583 } 2584 2585 DB_SHOW_ALL_COMMAND(locks, db_witness_list_all) 2586 { 2587 struct thread *td; 2588 struct proc *p; 2589 2590 /* 2591 * It would be nice to list only threads and processes that actually 2592 * held sleep locks, but that information is currently not exported 2593 * by WITNESS. 2594 */ 2595 FOREACH_PROC_IN_SYSTEM(p) { 2596 if (!witness_proc_has_locks(p)) 2597 continue; 2598 FOREACH_THREAD_IN_PROC(p, td) { 2599 if (!witness_thread_has_locks(td)) 2600 continue; 2601 db_printf("Process %d (%s) thread %p (%d)\n", p->p_pid, 2602 p->p_comm, td, td->td_tid); 2603 witness_ddb_list(td); 2604 if (db_pager_quit) 2605 return; 2606 } 2607 } 2608 } 2609 DB_SHOW_ALIAS(alllocks, db_witness_list_all) 2610 2611 DB_SHOW_COMMAND(witness, db_witness_display) 2612 { 2613 2614 witness_ddb_display(db_printf); 2615 } 2616 #endif 2617 2618 static void 2619 sbuf_print_witness_badstacks(struct sbuf *sb, size_t *oldidx) 2620 { 2621 struct witness_lock_order_data *data1, *data2, *tmp_data1, *tmp_data2; 2622 struct witness *tmp_w1, *tmp_w2, *w1, *w2; 2623 int generation, i, j; 2624 2625 tmp_data1 = NULL; 2626 tmp_data2 = NULL; 2627 tmp_w1 = NULL; 2628 tmp_w2 = NULL; 2629 2630 /* Allocate and init temporary storage space. */ 2631 tmp_w1 = malloc(sizeof(struct witness), M_TEMP, M_WAITOK | M_ZERO); 2632 tmp_w2 = malloc(sizeof(struct witness), M_TEMP, M_WAITOK | M_ZERO); 2633 tmp_data1 = malloc(sizeof(struct witness_lock_order_data), M_TEMP, 2634 M_WAITOK | M_ZERO); 2635 tmp_data2 = malloc(sizeof(struct witness_lock_order_data), M_TEMP, 2636 M_WAITOK | M_ZERO); 2637 stack_zero(&tmp_data1->wlod_stack); 2638 stack_zero(&tmp_data2->wlod_stack); 2639 2640 restart: 2641 mtx_lock_spin(&w_mtx); 2642 generation = w_generation; 2643 mtx_unlock_spin(&w_mtx); 2644 sbuf_printf(sb, "Number of known direct relationships is %d\n", 2645 w_lohash.wloh_count); 2646 for (i = 1; i < w_max_used_index; i++) { 2647 mtx_lock_spin(&w_mtx); 2648 if (generation != w_generation) { 2649 mtx_unlock_spin(&w_mtx); 2650 2651 /* The graph has changed, try again. */ 2652 *oldidx = 0; 2653 sbuf_clear(sb); 2654 goto restart; 2655 } 2656 2657 w1 = &w_data[i]; 2658 if (w1->w_reversed == 0) { 2659 mtx_unlock_spin(&w_mtx); 2660 continue; 2661 } 2662 2663 /* Copy w1 locally so we can release the spin lock. */ 2664 *tmp_w1 = *w1; 2665 mtx_unlock_spin(&w_mtx); 2666 2667 if (tmp_w1->w_reversed == 0) 2668 continue; 2669 for (j = 1; j < w_max_used_index; j++) { 2670 if ((w_rmatrix[i][j] & WITNESS_REVERSAL) == 0 || i > j) 2671 continue; 2672 2673 mtx_lock_spin(&w_mtx); 2674 if (generation != w_generation) { 2675 mtx_unlock_spin(&w_mtx); 2676 2677 /* The graph has changed, try again. */ 2678 *oldidx = 0; 2679 sbuf_clear(sb); 2680 goto restart; 2681 } 2682 2683 w2 = &w_data[j]; 2684 data1 = witness_lock_order_get(w1, w2); 2685 data2 = witness_lock_order_get(w2, w1); 2686 2687 /* 2688 * Copy information locally so we can release the 2689 * spin lock. 2690 */ 2691 *tmp_w2 = *w2; 2692 2693 if (data1) { 2694 stack_zero(&tmp_data1->wlod_stack); 2695 stack_copy(&data1->wlod_stack, 2696 &tmp_data1->wlod_stack); 2697 } 2698 if (data2 && data2 != data1) { 2699 stack_zero(&tmp_data2->wlod_stack); 2700 stack_copy(&data2->wlod_stack, 2701 &tmp_data2->wlod_stack); 2702 } 2703 mtx_unlock_spin(&w_mtx); 2704 2705 if (blessed(tmp_w1, tmp_w2)) 2706 continue; 2707 2708 sbuf_printf(sb, 2709 "\nLock order reversal between \"%s\"(%s) and \"%s\"(%s)!\n", 2710 tmp_w1->w_name, tmp_w1->w_class->lc_name, 2711 tmp_w2->w_name, tmp_w2->w_class->lc_name); 2712 if (data1) { 2713 sbuf_printf(sb, 2714 "Lock order \"%s\"(%s) -> \"%s\"(%s) first seen at:\n", 2715 tmp_w1->w_name, tmp_w1->w_class->lc_name, 2716 tmp_w2->w_name, tmp_w2->w_class->lc_name); 2717 stack_sbuf_print(sb, &tmp_data1->wlod_stack); 2718 sbuf_printf(sb, "\n"); 2719 } 2720 if (data2 && data2 != data1) { 2721 sbuf_printf(sb, 2722 "Lock order \"%s\"(%s) -> \"%s\"(%s) first seen at:\n", 2723 tmp_w2->w_name, tmp_w2->w_class->lc_name, 2724 tmp_w1->w_name, tmp_w1->w_class->lc_name); 2725 stack_sbuf_print(sb, &tmp_data2->wlod_stack); 2726 sbuf_printf(sb, "\n"); 2727 } 2728 } 2729 } 2730 mtx_lock_spin(&w_mtx); 2731 if (generation != w_generation) { 2732 mtx_unlock_spin(&w_mtx); 2733 2734 /* 2735 * The graph changed while we were printing stack data, 2736 * try again. 2737 */ 2738 *oldidx = 0; 2739 sbuf_clear(sb); 2740 goto restart; 2741 } 2742 mtx_unlock_spin(&w_mtx); 2743 2744 /* Free temporary storage space. */ 2745 free(tmp_data1, M_TEMP); 2746 free(tmp_data2, M_TEMP); 2747 free(tmp_w1, M_TEMP); 2748 free(tmp_w2, M_TEMP); 2749 } 2750 2751 static int 2752 sysctl_debug_witness_badstacks(SYSCTL_HANDLER_ARGS) 2753 { 2754 struct sbuf *sb; 2755 int error; 2756 2757 if (witness_watch < 1) { 2758 error = SYSCTL_OUT(req, w_notrunning, sizeof(w_notrunning)); 2759 return (error); 2760 } 2761 if (witness_cold) { 2762 error = SYSCTL_OUT(req, w_stillcold, sizeof(w_stillcold)); 2763 return (error); 2764 } 2765 error = 0; 2766 sb = sbuf_new(NULL, NULL, badstack_sbuf_size, SBUF_AUTOEXTEND); 2767 if (sb == NULL) 2768 return (ENOMEM); 2769 2770 sbuf_print_witness_badstacks(sb, &req->oldidx); 2771 2772 sbuf_finish(sb); 2773 error = SYSCTL_OUT(req, sbuf_data(sb), sbuf_len(sb) + 1); 2774 sbuf_delete(sb); 2775 2776 return (error); 2777 } 2778 2779 #ifdef DDB 2780 static int 2781 sbuf_db_printf_drain(void *arg __unused, const char *data, int len) 2782 { 2783 2784 return (db_printf("%.*s", len, data)); 2785 } 2786 2787 DB_SHOW_COMMAND(badstacks, db_witness_badstacks) 2788 { 2789 struct sbuf sb; 2790 char buffer[128]; 2791 size_t dummy; 2792 2793 sbuf_new(&sb, buffer, sizeof(buffer), SBUF_FIXEDLEN); 2794 sbuf_set_drain(&sb, sbuf_db_printf_drain, NULL); 2795 sbuf_print_witness_badstacks(&sb, &dummy); 2796 sbuf_finish(&sb); 2797 } 2798 #endif 2799 2800 static int 2801 sysctl_debug_witness_channel(SYSCTL_HANDLER_ARGS) 2802 { 2803 static const struct { 2804 enum witness_channel channel; 2805 const char *name; 2806 } channels[] = { 2807 { WITNESS_CONSOLE, "console" }, 2808 { WITNESS_LOG, "log" }, 2809 { WITNESS_NONE, "none" }, 2810 }; 2811 char buf[16]; 2812 u_int i; 2813 int error; 2814 2815 buf[0] = '\0'; 2816 for (i = 0; i < nitems(channels); i++) 2817 if (witness_channel == channels[i].channel) { 2818 snprintf(buf, sizeof(buf), "%s", channels[i].name); 2819 break; 2820 } 2821 2822 error = sysctl_handle_string(oidp, buf, sizeof(buf), req); 2823 if (error != 0 || req->newptr == NULL) 2824 return (error); 2825 2826 error = EINVAL; 2827 for (i = 0; i < nitems(channels); i++) 2828 if (strcmp(channels[i].name, buf) == 0) { 2829 witness_channel = channels[i].channel; 2830 error = 0; 2831 break; 2832 } 2833 return (error); 2834 } 2835 2836 static int 2837 sysctl_debug_witness_fullgraph(SYSCTL_HANDLER_ARGS) 2838 { 2839 struct witness *w; 2840 struct sbuf *sb; 2841 int error; 2842 2843 #ifdef __i386__ 2844 error = SYSCTL_OUT(req, w_notallowed, sizeof(w_notallowed)); 2845 return (error); 2846 #endif 2847 2848 if (witness_watch < 1) { 2849 error = SYSCTL_OUT(req, w_notrunning, sizeof(w_notrunning)); 2850 return (error); 2851 } 2852 if (witness_cold) { 2853 error = SYSCTL_OUT(req, w_stillcold, sizeof(w_stillcold)); 2854 return (error); 2855 } 2856 error = 0; 2857 2858 error = sysctl_wire_old_buffer(req, 0); 2859 if (error != 0) 2860 return (error); 2861 sb = sbuf_new_for_sysctl(NULL, NULL, FULLGRAPH_SBUF_SIZE, req); 2862 if (sb == NULL) 2863 return (ENOMEM); 2864 sbuf_printf(sb, "\n"); 2865 2866 mtx_lock_spin(&w_mtx); 2867 STAILQ_FOREACH(w, &w_all, w_list) 2868 w->w_displayed = 0; 2869 STAILQ_FOREACH(w, &w_all, w_list) 2870 witness_add_fullgraph(sb, w); 2871 mtx_unlock_spin(&w_mtx); 2872 2873 /* 2874 * Close the sbuf and return to userland. 2875 */ 2876 error = sbuf_finish(sb); 2877 sbuf_delete(sb); 2878 2879 return (error); 2880 } 2881 2882 static int 2883 sysctl_debug_witness_watch(SYSCTL_HANDLER_ARGS) 2884 { 2885 int error, value; 2886 2887 value = witness_watch; 2888 error = sysctl_handle_int(oidp, &value, 0, req); 2889 if (error != 0 || req->newptr == NULL) 2890 return (error); 2891 if (value > 1 || value < -1 || 2892 (witness_watch == -1 && value != witness_watch)) 2893 return (EINVAL); 2894 witness_watch = value; 2895 return (0); 2896 } 2897 2898 static void 2899 witness_add_fullgraph(struct sbuf *sb, struct witness *w) 2900 { 2901 int i; 2902 2903 if (w->w_displayed != 0 || (w->w_file == NULL && w->w_line == 0)) 2904 return; 2905 w->w_displayed = 1; 2906 2907 WITNESS_INDEX_ASSERT(w->w_index); 2908 for (i = 1; i <= w_max_used_index; i++) { 2909 if (w_rmatrix[w->w_index][i] & WITNESS_PARENT) { 2910 sbuf_printf(sb, "\"%s\",\"%s\"\n", w->w_name, 2911 w_data[i].w_name); 2912 witness_add_fullgraph(sb, &w_data[i]); 2913 } 2914 } 2915 } 2916 2917 /* 2918 * A simple hash function. Takes a key pointer and a key size. If size == 0, 2919 * interprets the key as a string and reads until the null 2920 * terminator. Otherwise, reads the first size bytes. Returns an unsigned 32-bit 2921 * hash value computed from the key. 2922 */ 2923 static uint32_t 2924 witness_hash_djb2(const uint8_t *key, uint32_t size) 2925 { 2926 unsigned int hash = 5381; 2927 int i; 2928 2929 /* hash = hash * 33 + key[i] */ 2930 if (size) 2931 for (i = 0; i < size; i++) 2932 hash = ((hash << 5) + hash) + (unsigned int)key[i]; 2933 else 2934 for (i = 0; key[i] != 0; i++) 2935 hash = ((hash << 5) + hash) + (unsigned int)key[i]; 2936 2937 return (hash); 2938 } 2939 2940 /* 2941 * Initializes the two witness hash tables. Called exactly once from 2942 * witness_initialize(). 2943 */ 2944 static void 2945 witness_init_hash_tables(void) 2946 { 2947 int i; 2948 2949 MPASS(witness_cold); 2950 2951 /* Initialize the hash tables. */ 2952 for (i = 0; i < WITNESS_HASH_SIZE; i++) 2953 w_hash.wh_array[i] = NULL; 2954 2955 w_hash.wh_size = WITNESS_HASH_SIZE; 2956 w_hash.wh_count = 0; 2957 2958 /* Initialize the lock order data hash. */ 2959 w_lofree = NULL; 2960 for (i = 0; i < WITNESS_LO_DATA_COUNT; i++) { 2961 memset(&w_lodata[i], 0, sizeof(w_lodata[i])); 2962 w_lodata[i].wlod_next = w_lofree; 2963 w_lofree = &w_lodata[i]; 2964 } 2965 w_lohash.wloh_size = WITNESS_LO_HASH_SIZE; 2966 w_lohash.wloh_count = 0; 2967 for (i = 0; i < WITNESS_LO_HASH_SIZE; i++) 2968 w_lohash.wloh_array[i] = NULL; 2969 } 2970 2971 static struct witness * 2972 witness_hash_get(const char *key) 2973 { 2974 struct witness *w; 2975 uint32_t hash; 2976 2977 MPASS(key != NULL); 2978 if (witness_cold == 0) 2979 mtx_assert(&w_mtx, MA_OWNED); 2980 hash = witness_hash_djb2(key, 0) % w_hash.wh_size; 2981 w = w_hash.wh_array[hash]; 2982 while (w != NULL) { 2983 if (strcmp(w->w_name, key) == 0) 2984 goto out; 2985 w = w->w_hash_next; 2986 } 2987 2988 out: 2989 return (w); 2990 } 2991 2992 static void 2993 witness_hash_put(struct witness *w) 2994 { 2995 uint32_t hash; 2996 2997 MPASS(w != NULL); 2998 MPASS(w->w_name != NULL); 2999 if (witness_cold == 0) 3000 mtx_assert(&w_mtx, MA_OWNED); 3001 KASSERT(witness_hash_get(w->w_name) == NULL, 3002 ("%s: trying to add a hash entry that already exists!", __func__)); 3003 KASSERT(w->w_hash_next == NULL, 3004 ("%s: w->w_hash_next != NULL", __func__)); 3005 3006 hash = witness_hash_djb2(w->w_name, 0) % w_hash.wh_size; 3007 w->w_hash_next = w_hash.wh_array[hash]; 3008 w_hash.wh_array[hash] = w; 3009 w_hash.wh_count++; 3010 } 3011 3012 static struct witness_lock_order_data * 3013 witness_lock_order_get(struct witness *parent, struct witness *child) 3014 { 3015 struct witness_lock_order_data *data = NULL; 3016 struct witness_lock_order_key key; 3017 unsigned int hash; 3018 3019 MPASS(parent != NULL && child != NULL); 3020 key.from = parent->w_index; 3021 key.to = child->w_index; 3022 WITNESS_INDEX_ASSERT(key.from); 3023 WITNESS_INDEX_ASSERT(key.to); 3024 if ((w_rmatrix[parent->w_index][child->w_index] 3025 & WITNESS_LOCK_ORDER_KNOWN) == 0) 3026 goto out; 3027 3028 hash = witness_hash_djb2((const char*)&key, 3029 sizeof(key)) % w_lohash.wloh_size; 3030 data = w_lohash.wloh_array[hash]; 3031 while (data != NULL) { 3032 if (witness_lock_order_key_equal(&data->wlod_key, &key)) 3033 break; 3034 data = data->wlod_next; 3035 } 3036 3037 out: 3038 return (data); 3039 } 3040 3041 /* 3042 * Verify that parent and child have a known relationship, are not the same, 3043 * and child is actually a child of parent. This is done without w_mtx 3044 * to avoid contention in the common case. 3045 */ 3046 static int 3047 witness_lock_order_check(struct witness *parent, struct witness *child) 3048 { 3049 3050 if (parent != child && 3051 w_rmatrix[parent->w_index][child->w_index] 3052 & WITNESS_LOCK_ORDER_KNOWN && 3053 isitmychild(parent, child)) 3054 return (1); 3055 3056 return (0); 3057 } 3058 3059 static int 3060 witness_lock_order_add(struct witness *parent, struct witness *child) 3061 { 3062 struct witness_lock_order_data *data = NULL; 3063 struct witness_lock_order_key key; 3064 unsigned int hash; 3065 3066 MPASS(parent != NULL && child != NULL); 3067 key.from = parent->w_index; 3068 key.to = child->w_index; 3069 WITNESS_INDEX_ASSERT(key.from); 3070 WITNESS_INDEX_ASSERT(key.to); 3071 if (w_rmatrix[parent->w_index][child->w_index] 3072 & WITNESS_LOCK_ORDER_KNOWN) 3073 return (1); 3074 3075 hash = witness_hash_djb2((const char*)&key, 3076 sizeof(key)) % w_lohash.wloh_size; 3077 w_rmatrix[parent->w_index][child->w_index] |= WITNESS_LOCK_ORDER_KNOWN; 3078 data = w_lofree; 3079 if (data == NULL) 3080 return (0); 3081 w_lofree = data->wlod_next; 3082 data->wlod_next = w_lohash.wloh_array[hash]; 3083 data->wlod_key = key; 3084 w_lohash.wloh_array[hash] = data; 3085 w_lohash.wloh_count++; 3086 stack_zero(&data->wlod_stack); 3087 stack_save(&data->wlod_stack); 3088 return (1); 3089 } 3090 3091 /* Call this whenever the structure of the witness graph changes. */ 3092 static void 3093 witness_increment_graph_generation(void) 3094 { 3095 3096 if (witness_cold == 0) 3097 mtx_assert(&w_mtx, MA_OWNED); 3098 w_generation++; 3099 } 3100 3101 static int 3102 witness_output_drain(void *arg __unused, const char *data, int len) 3103 { 3104 3105 witness_output("%.*s", len, data); 3106 return (len); 3107 } 3108 3109 static void 3110 witness_debugger(int cond, const char *msg) 3111 { 3112 char buf[32]; 3113 struct sbuf sb; 3114 struct stack st; 3115 3116 if (!cond) 3117 return; 3118 3119 if (witness_trace) { 3120 sbuf_new(&sb, buf, sizeof(buf), SBUF_FIXEDLEN); 3121 sbuf_set_drain(&sb, witness_output_drain, NULL); 3122 3123 stack_zero(&st); 3124 stack_save(&st); 3125 witness_output("stack backtrace:\n"); 3126 stack_sbuf_print_ddb(&sb, &st); 3127 3128 sbuf_finish(&sb); 3129 } 3130 3131 witness_enter_debugger(msg); 3132 } 3133 3134 static void 3135 witness_enter_debugger(const char *msg) 3136 { 3137 #ifdef KDB 3138 if (witness_kdb) 3139 kdb_enter(KDB_WHY_WITNESS, msg); 3140 #endif 3141 } 3142