1 /*- 2 * SPDX-License-Identifier: BSD-3-Clause 3 * 4 * Copyright (c) 2008 Isilon Systems, Inc. 5 * Copyright (c) 2008 Ilya Maykov <ivmaykov@gmail.com> 6 * Copyright (c) 1998 Berkeley Software Design, Inc. 7 * All rights reserved. 8 * 9 * Redistribution and use in source and binary forms, with or without 10 * modification, are permitted provided that the following conditions 11 * are met: 12 * 1. Redistributions of source code must retain the above copyright 13 * notice, this list of conditions and the following disclaimer. 14 * 2. Redistributions in binary form must reproduce the above copyright 15 * notice, this list of conditions and the following disclaimer in the 16 * documentation and/or other materials provided with the distribution. 17 * 3. Berkeley Software Design Inc's name may not be used to endorse or 18 * promote products derived from this software without specific prior 19 * written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY BERKELEY SOFTWARE DESIGN INC ``AS IS'' AND 22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24 * ARE DISCLAIMED. IN NO EVENT SHALL BERKELEY SOFTWARE DESIGN INC BE LIABLE 25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31 * SUCH DAMAGE. 32 * 33 * from BSDI $Id: mutex_witness.c,v 1.1.2.20 2000/04/27 03:10:27 cp Exp $ 34 * and BSDI $Id: synch_machdep.c,v 2.3.2.39 2000/04/27 03:10:25 cp Exp $ 35 */ 36 37 /* 38 * Implementation of the `witness' lock verifier. Originally implemented for 39 * mutexes in BSD/OS. Extended to handle generic lock objects and lock 40 * classes in FreeBSD. 41 */ 42 43 /* 44 * Main Entry: witness 45 * Pronunciation: 'wit-n&s 46 * Function: noun 47 * Etymology: Middle English witnesse, from Old English witnes knowledge, 48 * testimony, witness, from 2wit 49 * Date: before 12th century 50 * 1 : attestation of a fact or event : TESTIMONY 51 * 2 : one that gives evidence; specifically : one who testifies in 52 * a cause or before a judicial tribunal 53 * 3 : one asked to be present at a transaction so as to be able to 54 * testify to its having taken place 55 * 4 : one who has personal knowledge of something 56 * 5 a : something serving as evidence or proof : SIGN 57 * b : public affirmation by word or example of usually 58 * religious faith or conviction <the heroic witness to divine 59 * life -- Pilot> 60 * 6 capitalized : a member of the Jehovah's Witnesses 61 */ 62 63 /* 64 * Special rules concerning Giant and lock orders: 65 * 66 * 1) Giant must be acquired before any other mutexes. Stated another way, 67 * no other mutex may be held when Giant is acquired. 68 * 69 * 2) Giant must be released when blocking on a sleepable lock. 70 * 71 * This rule is less obvious, but is a result of Giant providing the same 72 * semantics as spl(). Basically, when a thread sleeps, it must release 73 * Giant. When a thread blocks on a sleepable lock, it sleeps. Hence rule 74 * 2). 75 * 76 * 3) Giant may be acquired before or after sleepable locks. 77 * 78 * This rule is also not quite as obvious. Giant may be acquired after 79 * a sleepable lock because it is a non-sleepable lock and non-sleepable 80 * locks may always be acquired while holding a sleepable lock. The second 81 * case, Giant before a sleepable lock, follows from rule 2) above. Suppose 82 * you have two threads T1 and T2 and a sleepable lock X. Suppose that T1 83 * acquires X and blocks on Giant. Then suppose that T2 acquires Giant and 84 * blocks on X. When T2 blocks on X, T2 will release Giant allowing T1 to 85 * execute. Thus, acquiring Giant both before and after a sleepable lock 86 * will not result in a lock order reversal. 87 */ 88 89 #include <sys/cdefs.h> 90 __FBSDID("$FreeBSD$"); 91 92 #include "opt_ddb.h" 93 #include "opt_hwpmc_hooks.h" 94 #include "opt_stack.h" 95 #include "opt_witness.h" 96 97 #include <sys/param.h> 98 #include <sys/bus.h> 99 #include <sys/kdb.h> 100 #include <sys/kernel.h> 101 #include <sys/ktr.h> 102 #include <sys/lock.h> 103 #include <sys/malloc.h> 104 #include <sys/mutex.h> 105 #include <sys/priv.h> 106 #include <sys/proc.h> 107 #include <sys/sbuf.h> 108 #include <sys/sched.h> 109 #include <sys/stack.h> 110 #include <sys/sysctl.h> 111 #include <sys/syslog.h> 112 #include <sys/systm.h> 113 114 #ifdef DDB 115 #include <ddb/ddb.h> 116 #endif 117 118 #include <machine/stdarg.h> 119 120 #if !defined(DDB) && !defined(STACK) 121 #error "DDB or STACK options are required for WITNESS" 122 #endif 123 124 /* Note that these traces do not work with KTR_ALQ. */ 125 #if 0 126 #define KTR_WITNESS KTR_SUBSYS 127 #else 128 #define KTR_WITNESS 0 129 #endif 130 131 #define LI_RECURSEMASK 0x0000ffff /* Recursion depth of lock instance. */ 132 #define LI_EXCLUSIVE 0x00010000 /* Exclusive lock instance. */ 133 #define LI_NORELEASE 0x00020000 /* Lock not allowed to be released. */ 134 #define LI_SLEEPABLE 0x00040000 /* Lock may be held while sleeping. */ 135 136 #ifndef WITNESS_COUNT 137 #define WITNESS_COUNT 1536 138 #endif 139 #define WITNESS_HASH_SIZE 251 /* Prime, gives load factor < 2 */ 140 #define WITNESS_PENDLIST (512 + (MAXCPU * 4)) 141 142 /* Allocate 256 KB of stack data space */ 143 #define WITNESS_LO_DATA_COUNT 2048 144 145 /* Prime, gives load factor of ~2 at full load */ 146 #define WITNESS_LO_HASH_SIZE 1021 147 148 /* 149 * XXX: This is somewhat bogus, as we assume here that at most 2048 threads 150 * will hold LOCK_NCHILDREN locks. We handle failure ok, and we should 151 * probably be safe for the most part, but it's still a SWAG. 152 */ 153 #define LOCK_NCHILDREN 5 154 #define LOCK_CHILDCOUNT 2048 155 156 #define MAX_W_NAME 64 157 158 #define FULLGRAPH_SBUF_SIZE 512 159 160 /* 161 * These flags go in the witness relationship matrix and describe the 162 * relationship between any two struct witness objects. 163 */ 164 #define WITNESS_UNRELATED 0x00 /* No lock order relation. */ 165 #define WITNESS_PARENT 0x01 /* Parent, aka direct ancestor. */ 166 #define WITNESS_ANCESTOR 0x02 /* Direct or indirect ancestor. */ 167 #define WITNESS_CHILD 0x04 /* Child, aka direct descendant. */ 168 #define WITNESS_DESCENDANT 0x08 /* Direct or indirect descendant. */ 169 #define WITNESS_ANCESTOR_MASK (WITNESS_PARENT | WITNESS_ANCESTOR) 170 #define WITNESS_DESCENDANT_MASK (WITNESS_CHILD | WITNESS_DESCENDANT) 171 #define WITNESS_RELATED_MASK \ 172 (WITNESS_ANCESTOR_MASK | WITNESS_DESCENDANT_MASK) 173 #define WITNESS_REVERSAL 0x10 /* A lock order reversal has been 174 * observed. */ 175 #define WITNESS_RESERVED1 0x20 /* Unused flag, reserved. */ 176 #define WITNESS_RESERVED2 0x40 /* Unused flag, reserved. */ 177 #define WITNESS_LOCK_ORDER_KNOWN 0x80 /* This lock order is known. */ 178 179 /* Descendant to ancestor flags */ 180 #define WITNESS_DTOA(x) (((x) & WITNESS_RELATED_MASK) >> 2) 181 182 /* Ancestor to descendant flags */ 183 #define WITNESS_ATOD(x) (((x) & WITNESS_RELATED_MASK) << 2) 184 185 #define WITNESS_INDEX_ASSERT(i) \ 186 MPASS((i) > 0 && (i) <= w_max_used_index && (i) < witness_count) 187 188 static MALLOC_DEFINE(M_WITNESS, "Witness", "Witness"); 189 190 /* 191 * Lock instances. A lock instance is the data associated with a lock while 192 * it is held by witness. For example, a lock instance will hold the 193 * recursion count of a lock. Lock instances are held in lists. Spin locks 194 * are held in a per-cpu list while sleep locks are held in per-thread list. 195 */ 196 struct lock_instance { 197 struct lock_object *li_lock; 198 const char *li_file; 199 int li_line; 200 u_int li_flags; 201 }; 202 203 /* 204 * A simple list type used to build the list of locks held by a thread 205 * or CPU. We can't simply embed the list in struct lock_object since a 206 * lock may be held by more than one thread if it is a shared lock. Locks 207 * are added to the head of the list, so we fill up each list entry from 208 * "the back" logically. To ease some of the arithmetic, we actually fill 209 * in each list entry the normal way (children[0] then children[1], etc.) but 210 * when we traverse the list we read children[count-1] as the first entry 211 * down to children[0] as the final entry. 212 */ 213 struct lock_list_entry { 214 struct lock_list_entry *ll_next; 215 struct lock_instance ll_children[LOCK_NCHILDREN]; 216 u_int ll_count; 217 }; 218 219 /* 220 * The main witness structure. One of these per named lock type in the system 221 * (for example, "vnode interlock"). 222 */ 223 struct witness { 224 char w_name[MAX_W_NAME]; 225 uint32_t w_index; /* Index in the relationship matrix */ 226 struct lock_class *w_class; 227 STAILQ_ENTRY(witness) w_list; /* List of all witnesses. */ 228 STAILQ_ENTRY(witness) w_typelist; /* Witnesses of a type. */ 229 struct witness *w_hash_next; /* Linked list in hash buckets. */ 230 const char *w_file; /* File where last acquired */ 231 uint32_t w_line; /* Line where last acquired */ 232 uint32_t w_refcount; 233 uint16_t w_num_ancestors; /* direct/indirect 234 * ancestor count */ 235 uint16_t w_num_descendants; /* direct/indirect 236 * descendant count */ 237 int16_t w_ddb_level; 238 unsigned w_displayed:1; 239 unsigned w_reversed:1; 240 }; 241 242 STAILQ_HEAD(witness_list, witness); 243 244 /* 245 * The witness hash table. Keys are witness names (const char *), elements are 246 * witness objects (struct witness *). 247 */ 248 struct witness_hash { 249 struct witness *wh_array[WITNESS_HASH_SIZE]; 250 uint32_t wh_size; 251 uint32_t wh_count; 252 }; 253 254 /* 255 * Key type for the lock order data hash table. 256 */ 257 struct witness_lock_order_key { 258 uint16_t from; 259 uint16_t to; 260 }; 261 262 struct witness_lock_order_data { 263 struct stack wlod_stack; 264 struct witness_lock_order_key wlod_key; 265 struct witness_lock_order_data *wlod_next; 266 }; 267 268 /* 269 * The witness lock order data hash table. Keys are witness index tuples 270 * (struct witness_lock_order_key), elements are lock order data objects 271 * (struct witness_lock_order_data). 272 */ 273 struct witness_lock_order_hash { 274 struct witness_lock_order_data *wloh_array[WITNESS_LO_HASH_SIZE]; 275 u_int wloh_size; 276 u_int wloh_count; 277 }; 278 279 struct witness_blessed { 280 const char *b_lock1; 281 const char *b_lock2; 282 }; 283 284 struct witness_pendhelp { 285 const char *wh_type; 286 struct lock_object *wh_lock; 287 }; 288 289 struct witness_order_list_entry { 290 const char *w_name; 291 struct lock_class *w_class; 292 }; 293 294 /* 295 * Returns 0 if one of the locks is a spin lock and the other is not. 296 * Returns 1 otherwise. 297 */ 298 static __inline int 299 witness_lock_type_equal(struct witness *w1, struct witness *w2) 300 { 301 302 return ((w1->w_class->lc_flags & (LC_SLEEPLOCK | LC_SPINLOCK)) == 303 (w2->w_class->lc_flags & (LC_SLEEPLOCK | LC_SPINLOCK))); 304 } 305 306 static __inline int 307 witness_lock_order_key_equal(const struct witness_lock_order_key *a, 308 const struct witness_lock_order_key *b) 309 { 310 311 return (a->from == b->from && a->to == b->to); 312 } 313 314 static int _isitmyx(struct witness *w1, struct witness *w2, int rmask, 315 const char *fname); 316 static void adopt(struct witness *parent, struct witness *child); 317 static int blessed(struct witness *, struct witness *); 318 static void depart(struct witness *w); 319 static struct witness *enroll(const char *description, 320 struct lock_class *lock_class); 321 static struct lock_instance *find_instance(struct lock_list_entry *list, 322 const struct lock_object *lock); 323 static int isitmychild(struct witness *parent, struct witness *child); 324 static int isitmydescendant(struct witness *parent, struct witness *child); 325 static void itismychild(struct witness *parent, struct witness *child); 326 static int sysctl_debug_witness_badstacks(SYSCTL_HANDLER_ARGS); 327 static int sysctl_debug_witness_watch(SYSCTL_HANDLER_ARGS); 328 static int sysctl_debug_witness_fullgraph(SYSCTL_HANDLER_ARGS); 329 static int sysctl_debug_witness_channel(SYSCTL_HANDLER_ARGS); 330 static void witness_add_fullgraph(struct sbuf *sb, struct witness *parent); 331 #ifdef DDB 332 static void witness_ddb_compute_levels(void); 333 static void witness_ddb_display(int(*)(const char *fmt, ...)); 334 static void witness_ddb_display_descendants(int(*)(const char *fmt, ...), 335 struct witness *, int indent); 336 static void witness_ddb_display_list(int(*prnt)(const char *fmt, ...), 337 struct witness_list *list); 338 static void witness_ddb_level_descendants(struct witness *parent, int l); 339 static void witness_ddb_list(struct thread *td); 340 #endif 341 static void witness_debugger(int cond, const char *msg); 342 static void witness_free(struct witness *m); 343 static struct witness *witness_get(void); 344 static uint32_t witness_hash_djb2(const uint8_t *key, uint32_t size); 345 static struct witness *witness_hash_get(const char *key); 346 static void witness_hash_put(struct witness *w); 347 static void witness_init_hash_tables(void); 348 static void witness_increment_graph_generation(void); 349 static void witness_lock_list_free(struct lock_list_entry *lle); 350 static struct lock_list_entry *witness_lock_list_get(void); 351 static int witness_lock_order_add(struct witness *parent, 352 struct witness *child); 353 static int witness_lock_order_check(struct witness *parent, 354 struct witness *child); 355 static struct witness_lock_order_data *witness_lock_order_get( 356 struct witness *parent, 357 struct witness *child); 358 static void witness_list_lock(struct lock_instance *instance, 359 int (*prnt)(const char *fmt, ...)); 360 static int witness_output(const char *fmt, ...) __printflike(1, 2); 361 static int witness_voutput(const char *fmt, va_list ap) __printflike(1, 0); 362 static void witness_setflag(struct lock_object *lock, int flag, int set); 363 364 static SYSCTL_NODE(_debug, OID_AUTO, witness, CTLFLAG_RW, NULL, 365 "Witness Locking"); 366 367 /* 368 * If set to 0, lock order checking is disabled. If set to -1, 369 * witness is completely disabled. Otherwise witness performs full 370 * lock order checking for all locks. At runtime, lock order checking 371 * may be toggled. However, witness cannot be reenabled once it is 372 * completely disabled. 373 */ 374 static int witness_watch = 1; 375 SYSCTL_PROC(_debug_witness, OID_AUTO, watch, CTLFLAG_RWTUN | CTLTYPE_INT, NULL, 0, 376 sysctl_debug_witness_watch, "I", "witness is watching lock operations"); 377 378 #ifdef KDB 379 /* 380 * When KDB is enabled and witness_kdb is 1, it will cause the system 381 * to drop into kdebug() when: 382 * - a lock hierarchy violation occurs 383 * - locks are held when going to sleep. 384 */ 385 #ifdef WITNESS_KDB 386 int witness_kdb = 1; 387 #else 388 int witness_kdb = 0; 389 #endif 390 SYSCTL_INT(_debug_witness, OID_AUTO, kdb, CTLFLAG_RWTUN, &witness_kdb, 0, ""); 391 #endif /* KDB */ 392 393 #if defined(DDB) || defined(KDB) 394 /* 395 * When DDB or KDB is enabled and witness_trace is 1, it will cause the system 396 * to print a stack trace: 397 * - a lock hierarchy violation occurs 398 * - locks are held when going to sleep. 399 */ 400 int witness_trace = 1; 401 SYSCTL_INT(_debug_witness, OID_AUTO, trace, CTLFLAG_RWTUN, &witness_trace, 0, ""); 402 #endif /* DDB || KDB */ 403 404 #ifdef WITNESS_SKIPSPIN 405 int witness_skipspin = 1; 406 #else 407 int witness_skipspin = 0; 408 #endif 409 SYSCTL_INT(_debug_witness, OID_AUTO, skipspin, CTLFLAG_RDTUN, &witness_skipspin, 0, ""); 410 411 int badstack_sbuf_size; 412 413 int witness_count = WITNESS_COUNT; 414 SYSCTL_INT(_debug_witness, OID_AUTO, witness_count, CTLFLAG_RDTUN, 415 &witness_count, 0, ""); 416 417 /* 418 * Output channel for witness messages. By default we print to the console. 419 */ 420 enum witness_channel { 421 WITNESS_CONSOLE, 422 WITNESS_LOG, 423 WITNESS_NONE, 424 }; 425 426 static enum witness_channel witness_channel = WITNESS_CONSOLE; 427 SYSCTL_PROC(_debug_witness, OID_AUTO, output_channel, CTLTYPE_STRING | 428 CTLFLAG_RWTUN, NULL, 0, sysctl_debug_witness_channel, "A", 429 "Output channel for warnings"); 430 431 /* 432 * Call this to print out the relations between locks. 433 */ 434 SYSCTL_PROC(_debug_witness, OID_AUTO, fullgraph, CTLTYPE_STRING | CTLFLAG_RD, 435 NULL, 0, sysctl_debug_witness_fullgraph, "A", "Show locks relation graphs"); 436 437 /* 438 * Call this to print out the witness faulty stacks. 439 */ 440 SYSCTL_PROC(_debug_witness, OID_AUTO, badstacks, CTLTYPE_STRING | CTLFLAG_RD, 441 NULL, 0, sysctl_debug_witness_badstacks, "A", "Show bad witness stacks"); 442 443 static struct mtx w_mtx; 444 445 /* w_list */ 446 static struct witness_list w_free = STAILQ_HEAD_INITIALIZER(w_free); 447 static struct witness_list w_all = STAILQ_HEAD_INITIALIZER(w_all); 448 449 /* w_typelist */ 450 static struct witness_list w_spin = STAILQ_HEAD_INITIALIZER(w_spin); 451 static struct witness_list w_sleep = STAILQ_HEAD_INITIALIZER(w_sleep); 452 453 /* lock list */ 454 static struct lock_list_entry *w_lock_list_free = NULL; 455 static struct witness_pendhelp pending_locks[WITNESS_PENDLIST]; 456 static u_int pending_cnt; 457 458 static int w_free_cnt, w_spin_cnt, w_sleep_cnt; 459 SYSCTL_INT(_debug_witness, OID_AUTO, free_cnt, CTLFLAG_RD, &w_free_cnt, 0, ""); 460 SYSCTL_INT(_debug_witness, OID_AUTO, spin_cnt, CTLFLAG_RD, &w_spin_cnt, 0, ""); 461 SYSCTL_INT(_debug_witness, OID_AUTO, sleep_cnt, CTLFLAG_RD, &w_sleep_cnt, 0, 462 ""); 463 464 static struct witness *w_data; 465 static uint8_t **w_rmatrix; 466 static struct lock_list_entry w_locklistdata[LOCK_CHILDCOUNT]; 467 static struct witness_hash w_hash; /* The witness hash table. */ 468 469 /* The lock order data hash */ 470 static struct witness_lock_order_data w_lodata[WITNESS_LO_DATA_COUNT]; 471 static struct witness_lock_order_data *w_lofree = NULL; 472 static struct witness_lock_order_hash w_lohash; 473 static int w_max_used_index = 0; 474 static unsigned int w_generation = 0; 475 static const char w_notrunning[] = "Witness not running\n"; 476 static const char w_stillcold[] = "Witness is still cold\n"; 477 #ifdef __i386__ 478 static const char w_notallowed[] = "The sysctl is disabled on the arch\n"; 479 #endif 480 481 static struct witness_order_list_entry order_lists[] = { 482 /* 483 * sx locks 484 */ 485 { "proctree", &lock_class_sx }, 486 { "allproc", &lock_class_sx }, 487 { "allprison", &lock_class_sx }, 488 { NULL, NULL }, 489 /* 490 * Various mutexes 491 */ 492 { "Giant", &lock_class_mtx_sleep }, 493 { "pipe mutex", &lock_class_mtx_sleep }, 494 { "sigio lock", &lock_class_mtx_sleep }, 495 { "process group", &lock_class_mtx_sleep }, 496 #ifdef HWPMC_HOOKS 497 { "pmc-sleep", &lock_class_mtx_sleep }, 498 #endif 499 { "process lock", &lock_class_mtx_sleep }, 500 { "session", &lock_class_mtx_sleep }, 501 { "uidinfo hash", &lock_class_rw }, 502 { "time lock", &lock_class_mtx_sleep }, 503 { NULL, NULL }, 504 /* 505 * umtx 506 */ 507 { "umtx lock", &lock_class_mtx_sleep }, 508 { NULL, NULL }, 509 /* 510 * Sockets 511 */ 512 { "accept", &lock_class_mtx_sleep }, 513 { "so_snd", &lock_class_mtx_sleep }, 514 { "so_rcv", &lock_class_mtx_sleep }, 515 { "sellck", &lock_class_mtx_sleep }, 516 { NULL, NULL }, 517 /* 518 * Routing 519 */ 520 { "so_rcv", &lock_class_mtx_sleep }, 521 { "radix node head", &lock_class_rm }, 522 { "rtentry", &lock_class_mtx_sleep }, 523 { "ifaddr", &lock_class_mtx_sleep }, 524 { NULL, NULL }, 525 /* 526 * IPv4 multicast: 527 * protocol locks before interface locks, after UDP locks. 528 */ 529 { "in_multi_sx", &lock_class_sx }, 530 { "udpinp", &lock_class_rw }, 531 { "in_multi_list_mtx", &lock_class_mtx_sleep }, 532 { "igmp_mtx", &lock_class_mtx_sleep }, 533 { "ifnet_rw", &lock_class_rw }, 534 { "if_addr_lock", &lock_class_mtx_sleep }, 535 { NULL, NULL }, 536 /* 537 * IPv6 multicast: 538 * protocol locks before interface locks, after UDP locks. 539 */ 540 { "in6_multi_sx", &lock_class_sx }, 541 { "udpinp", &lock_class_rw }, 542 { "in6_multi_list_mtx", &lock_class_mtx_sleep }, 543 { "mld_mtx", &lock_class_mtx_sleep }, 544 { "ifnet_rw", &lock_class_rw }, 545 { "if_addr_lock", &lock_class_mtx_sleep }, 546 { NULL, NULL }, 547 /* 548 * UNIX Domain Sockets 549 */ 550 { "unp_link_rwlock", &lock_class_rw }, 551 { "unp_list_lock", &lock_class_mtx_sleep }, 552 { "unp", &lock_class_mtx_sleep }, 553 { "so_snd", &lock_class_mtx_sleep }, 554 { NULL, NULL }, 555 /* 556 * UDP/IP 557 */ 558 { "udp", &lock_class_mtx_sleep }, 559 { "udpinp", &lock_class_rw }, 560 { "so_snd", &lock_class_mtx_sleep }, 561 { NULL, NULL }, 562 /* 563 * TCP/IP 564 */ 565 { "tcp", &lock_class_mtx_sleep }, 566 { "tcpinp", &lock_class_rw }, 567 { "so_snd", &lock_class_mtx_sleep }, 568 { NULL, NULL }, 569 /* 570 * BPF 571 */ 572 { "bpf global lock", &lock_class_sx }, 573 { "bpf cdev lock", &lock_class_mtx_sleep }, 574 { NULL, NULL }, 575 /* 576 * NFS server 577 */ 578 { "nfsd_mtx", &lock_class_mtx_sleep }, 579 { "so_snd", &lock_class_mtx_sleep }, 580 { NULL, NULL }, 581 582 /* 583 * IEEE 802.11 584 */ 585 { "802.11 com lock", &lock_class_mtx_sleep}, 586 { NULL, NULL }, 587 /* 588 * Network drivers 589 */ 590 { "network driver", &lock_class_mtx_sleep}, 591 { NULL, NULL }, 592 593 /* 594 * Netgraph 595 */ 596 { "ng_node", &lock_class_mtx_sleep }, 597 { "ng_worklist", &lock_class_mtx_sleep }, 598 { NULL, NULL }, 599 /* 600 * CDEV 601 */ 602 { "vm map (system)", &lock_class_mtx_sleep }, 603 { "vnode interlock", &lock_class_mtx_sleep }, 604 { "cdev", &lock_class_mtx_sleep }, 605 { "devthrd", &lock_class_mtx_sleep }, 606 { NULL, NULL }, 607 /* 608 * VM 609 */ 610 { "vm map (user)", &lock_class_sx }, 611 { "vm object", &lock_class_rw }, 612 { "vm page", &lock_class_mtx_sleep }, 613 { "pmap pv global", &lock_class_rw }, 614 { "pmap", &lock_class_mtx_sleep }, 615 { "pmap pv list", &lock_class_rw }, 616 { "vm page free queue", &lock_class_mtx_sleep }, 617 { "vm pagequeue", &lock_class_mtx_sleep }, 618 { NULL, NULL }, 619 /* 620 * kqueue/VFS interaction 621 */ 622 { "kqueue", &lock_class_mtx_sleep }, 623 { "struct mount mtx", &lock_class_mtx_sleep }, 624 { "vnode interlock", &lock_class_mtx_sleep }, 625 { NULL, NULL }, 626 /* 627 * VFS namecache 628 */ 629 { "ncvn", &lock_class_mtx_sleep }, 630 { "ncbuc", &lock_class_rw }, 631 { "vnode interlock", &lock_class_mtx_sleep }, 632 { "ncneg", &lock_class_mtx_sleep }, 633 { NULL, NULL }, 634 /* 635 * ZFS locking 636 */ 637 { "dn->dn_mtx", &lock_class_sx }, 638 { "dr->dt.di.dr_mtx", &lock_class_sx }, 639 { "db->db_mtx", &lock_class_sx }, 640 { NULL, NULL }, 641 /* 642 * TCP log locks 643 */ 644 { "TCP ID tree", &lock_class_rw }, 645 { "tcp log id bucket", &lock_class_mtx_sleep }, 646 { "tcpinp", &lock_class_rw }, 647 { "TCP log expireq", &lock_class_mtx_sleep }, 648 { NULL, NULL }, 649 /* 650 * spin locks 651 */ 652 #ifdef SMP 653 { "ap boot", &lock_class_mtx_spin }, 654 #endif 655 { "rm.mutex_mtx", &lock_class_mtx_spin }, 656 { "sio", &lock_class_mtx_spin }, 657 #ifdef __i386__ 658 { "cy", &lock_class_mtx_spin }, 659 #endif 660 #ifdef __sparc64__ 661 { "pcib_mtx", &lock_class_mtx_spin }, 662 { "rtc_mtx", &lock_class_mtx_spin }, 663 #endif 664 { "scc_hwmtx", &lock_class_mtx_spin }, 665 { "uart_hwmtx", &lock_class_mtx_spin }, 666 { "fast_taskqueue", &lock_class_mtx_spin }, 667 { "intr table", &lock_class_mtx_spin }, 668 { "process slock", &lock_class_mtx_spin }, 669 { "syscons video lock", &lock_class_mtx_spin }, 670 { "sleepq chain", &lock_class_mtx_spin }, 671 { "rm_spinlock", &lock_class_mtx_spin }, 672 { "turnstile chain", &lock_class_mtx_spin }, 673 { "turnstile lock", &lock_class_mtx_spin }, 674 { "sched lock", &lock_class_mtx_spin }, 675 { "td_contested", &lock_class_mtx_spin }, 676 { "callout", &lock_class_mtx_spin }, 677 { "entropy harvest mutex", &lock_class_mtx_spin }, 678 #ifdef SMP 679 { "smp rendezvous", &lock_class_mtx_spin }, 680 #endif 681 #ifdef __powerpc__ 682 { "tlb0", &lock_class_mtx_spin }, 683 #endif 684 { NULL, NULL }, 685 { "sched lock", &lock_class_mtx_spin }, 686 #ifdef HWPMC_HOOKS 687 { "pmc-per-proc", &lock_class_mtx_spin }, 688 #endif 689 { NULL, NULL }, 690 /* 691 * leaf locks 692 */ 693 { "intrcnt", &lock_class_mtx_spin }, 694 { "icu", &lock_class_mtx_spin }, 695 #if defined(SMP) && defined(__sparc64__) 696 { "ipi", &lock_class_mtx_spin }, 697 #endif 698 #ifdef __i386__ 699 { "allpmaps", &lock_class_mtx_spin }, 700 { "descriptor tables", &lock_class_mtx_spin }, 701 #endif 702 { "clk", &lock_class_mtx_spin }, 703 { "cpuset", &lock_class_mtx_spin }, 704 { "mprof lock", &lock_class_mtx_spin }, 705 { "zombie lock", &lock_class_mtx_spin }, 706 { "ALD Queue", &lock_class_mtx_spin }, 707 #if defined(__i386__) || defined(__amd64__) 708 { "pcicfg", &lock_class_mtx_spin }, 709 { "NDIS thread lock", &lock_class_mtx_spin }, 710 #endif 711 { "tw_osl_io_lock", &lock_class_mtx_spin }, 712 { "tw_osl_q_lock", &lock_class_mtx_spin }, 713 { "tw_cl_io_lock", &lock_class_mtx_spin }, 714 { "tw_cl_intr_lock", &lock_class_mtx_spin }, 715 { "tw_cl_gen_lock", &lock_class_mtx_spin }, 716 #ifdef HWPMC_HOOKS 717 { "pmc-leaf", &lock_class_mtx_spin }, 718 #endif 719 { "blocked lock", &lock_class_mtx_spin }, 720 { NULL, NULL }, 721 { NULL, NULL } 722 }; 723 724 /* 725 * Pairs of locks which have been blessed. Witness does not complain about 726 * order problems with blessed lock pairs. Please do not add an entry to the 727 * table without an explanatory comment. 728 */ 729 static struct witness_blessed blessed_list[] = { 730 /* 731 * See the comment in ufs_dirhash.c. Basically, a vnode lock serializes 732 * both lock orders, so a deadlock cannot happen as a result of this 733 * LOR. 734 */ 735 { "dirhash", "bufwait" }, 736 737 /* 738 * A UFS vnode may be locked in vget() while a buffer belonging to the 739 * parent directory vnode is locked. 740 */ 741 { "ufs", "bufwait" }, 742 }; 743 744 /* 745 * This global is set to 0 once it becomes safe to use the witness code. 746 */ 747 static int witness_cold = 1; 748 749 /* 750 * This global is set to 1 once the static lock orders have been enrolled 751 * so that a warning can be issued for any spin locks enrolled later. 752 */ 753 static int witness_spin_warn = 0; 754 755 /* Trim useless garbage from filenames. */ 756 static const char * 757 fixup_filename(const char *file) 758 { 759 760 if (file == NULL) 761 return (NULL); 762 while (strncmp(file, "../", 3) == 0) 763 file += 3; 764 return (file); 765 } 766 767 /* 768 * Calculate the size of early witness structures. 769 */ 770 int 771 witness_startup_count(void) 772 { 773 int sz; 774 775 sz = sizeof(struct witness) * witness_count; 776 sz += sizeof(*w_rmatrix) * (witness_count + 1); 777 sz += sizeof(*w_rmatrix[0]) * (witness_count + 1) * 778 (witness_count + 1); 779 780 return (sz); 781 } 782 783 /* 784 * The WITNESS-enabled diagnostic code. Note that the witness code does 785 * assume that the early boot is single-threaded at least until after this 786 * routine is completed. 787 */ 788 void 789 witness_startup(void *mem) 790 { 791 struct lock_object *lock; 792 struct witness_order_list_entry *order; 793 struct witness *w, *w1; 794 uintptr_t p; 795 int i; 796 797 p = (uintptr_t)mem; 798 w_data = (void *)p; 799 p += sizeof(struct witness) * witness_count; 800 801 w_rmatrix = (void *)p; 802 p += sizeof(*w_rmatrix) * (witness_count + 1); 803 804 for (i = 0; i < witness_count + 1; i++) { 805 w_rmatrix[i] = (void *)p; 806 p += sizeof(*w_rmatrix[i]) * (witness_count + 1); 807 } 808 badstack_sbuf_size = witness_count * 256; 809 810 /* 811 * We have to release Giant before initializing its witness 812 * structure so that WITNESS doesn't get confused. 813 */ 814 mtx_unlock(&Giant); 815 mtx_assert(&Giant, MA_NOTOWNED); 816 817 CTR1(KTR_WITNESS, "%s: initializing witness", __func__); 818 mtx_init(&w_mtx, "witness lock", NULL, MTX_SPIN | MTX_QUIET | 819 MTX_NOWITNESS | MTX_NOPROFILE); 820 for (i = witness_count - 1; i >= 0; i--) { 821 w = &w_data[i]; 822 memset(w, 0, sizeof(*w)); 823 w_data[i].w_index = i; /* Witness index never changes. */ 824 witness_free(w); 825 } 826 KASSERT(STAILQ_FIRST(&w_free)->w_index == 0, 827 ("%s: Invalid list of free witness objects", __func__)); 828 829 /* Witness with index 0 is not used to aid in debugging. */ 830 STAILQ_REMOVE_HEAD(&w_free, w_list); 831 w_free_cnt--; 832 833 for (i = 0; i < witness_count; i++) { 834 memset(w_rmatrix[i], 0, sizeof(*w_rmatrix[i]) * 835 (witness_count + 1)); 836 } 837 838 for (i = 0; i < LOCK_CHILDCOUNT; i++) 839 witness_lock_list_free(&w_locklistdata[i]); 840 witness_init_hash_tables(); 841 842 /* First add in all the specified order lists. */ 843 for (order = order_lists; order->w_name != NULL; order++) { 844 w = enroll(order->w_name, order->w_class); 845 if (w == NULL) 846 continue; 847 w->w_file = "order list"; 848 for (order++; order->w_name != NULL; order++) { 849 w1 = enroll(order->w_name, order->w_class); 850 if (w1 == NULL) 851 continue; 852 w1->w_file = "order list"; 853 itismychild(w, w1); 854 w = w1; 855 } 856 } 857 witness_spin_warn = 1; 858 859 /* Iterate through all locks and add them to witness. */ 860 for (i = 0; pending_locks[i].wh_lock != NULL; i++) { 861 lock = pending_locks[i].wh_lock; 862 KASSERT(lock->lo_flags & LO_WITNESS, 863 ("%s: lock %s is on pending list but not LO_WITNESS", 864 __func__, lock->lo_name)); 865 lock->lo_witness = enroll(pending_locks[i].wh_type, 866 LOCK_CLASS(lock)); 867 } 868 869 /* Mark the witness code as being ready for use. */ 870 witness_cold = 0; 871 872 mtx_lock(&Giant); 873 } 874 875 void 876 witness_init(struct lock_object *lock, const char *type) 877 { 878 struct lock_class *class; 879 880 /* Various sanity checks. */ 881 class = LOCK_CLASS(lock); 882 if ((lock->lo_flags & LO_RECURSABLE) != 0 && 883 (class->lc_flags & LC_RECURSABLE) == 0) 884 kassert_panic("%s: lock (%s) %s can not be recursable", 885 __func__, class->lc_name, lock->lo_name); 886 if ((lock->lo_flags & LO_SLEEPABLE) != 0 && 887 (class->lc_flags & LC_SLEEPABLE) == 0) 888 kassert_panic("%s: lock (%s) %s can not be sleepable", 889 __func__, class->lc_name, lock->lo_name); 890 if ((lock->lo_flags & LO_UPGRADABLE) != 0 && 891 (class->lc_flags & LC_UPGRADABLE) == 0) 892 kassert_panic("%s: lock (%s) %s can not be upgradable", 893 __func__, class->lc_name, lock->lo_name); 894 895 /* 896 * If we shouldn't watch this lock, then just clear lo_witness. 897 * Otherwise, if witness_cold is set, then it is too early to 898 * enroll this lock, so defer it to witness_initialize() by adding 899 * it to the pending_locks list. If it is not too early, then enroll 900 * the lock now. 901 */ 902 if (witness_watch < 1 || KERNEL_PANICKED() || 903 (lock->lo_flags & LO_WITNESS) == 0) 904 lock->lo_witness = NULL; 905 else if (witness_cold) { 906 pending_locks[pending_cnt].wh_lock = lock; 907 pending_locks[pending_cnt++].wh_type = type; 908 if (pending_cnt > WITNESS_PENDLIST) 909 panic("%s: pending locks list is too small, " 910 "increase WITNESS_PENDLIST\n", 911 __func__); 912 } else 913 lock->lo_witness = enroll(type, class); 914 } 915 916 void 917 witness_destroy(struct lock_object *lock) 918 { 919 struct lock_class *class; 920 struct witness *w; 921 922 class = LOCK_CLASS(lock); 923 924 if (witness_cold) 925 panic("lock (%s) %s destroyed while witness_cold", 926 class->lc_name, lock->lo_name); 927 928 /* XXX: need to verify that no one holds the lock */ 929 if ((lock->lo_flags & LO_WITNESS) == 0 || lock->lo_witness == NULL) 930 return; 931 w = lock->lo_witness; 932 933 mtx_lock_spin(&w_mtx); 934 MPASS(w->w_refcount > 0); 935 w->w_refcount--; 936 937 if (w->w_refcount == 0) 938 depart(w); 939 mtx_unlock_spin(&w_mtx); 940 } 941 942 #ifdef DDB 943 static void 944 witness_ddb_compute_levels(void) 945 { 946 struct witness *w; 947 948 /* 949 * First clear all levels. 950 */ 951 STAILQ_FOREACH(w, &w_all, w_list) 952 w->w_ddb_level = -1; 953 954 /* 955 * Look for locks with no parents and level all their descendants. 956 */ 957 STAILQ_FOREACH(w, &w_all, w_list) { 958 959 /* If the witness has ancestors (is not a root), skip it. */ 960 if (w->w_num_ancestors > 0) 961 continue; 962 witness_ddb_level_descendants(w, 0); 963 } 964 } 965 966 static void 967 witness_ddb_level_descendants(struct witness *w, int l) 968 { 969 int i; 970 971 if (w->w_ddb_level >= l) 972 return; 973 974 w->w_ddb_level = l; 975 l++; 976 977 for (i = 1; i <= w_max_used_index; i++) { 978 if (w_rmatrix[w->w_index][i] & WITNESS_PARENT) 979 witness_ddb_level_descendants(&w_data[i], l); 980 } 981 } 982 983 static void 984 witness_ddb_display_descendants(int(*prnt)(const char *fmt, ...), 985 struct witness *w, int indent) 986 { 987 int i; 988 989 for (i = 0; i < indent; i++) 990 prnt(" "); 991 prnt("%s (type: %s, depth: %d, active refs: %d)", 992 w->w_name, w->w_class->lc_name, 993 w->w_ddb_level, w->w_refcount); 994 if (w->w_displayed) { 995 prnt(" -- (already displayed)\n"); 996 return; 997 } 998 w->w_displayed = 1; 999 if (w->w_file != NULL && w->w_line != 0) 1000 prnt(" -- last acquired @ %s:%d\n", fixup_filename(w->w_file), 1001 w->w_line); 1002 else 1003 prnt(" -- never acquired\n"); 1004 indent++; 1005 WITNESS_INDEX_ASSERT(w->w_index); 1006 for (i = 1; i <= w_max_used_index; i++) { 1007 if (db_pager_quit) 1008 return; 1009 if (w_rmatrix[w->w_index][i] & WITNESS_PARENT) 1010 witness_ddb_display_descendants(prnt, &w_data[i], 1011 indent); 1012 } 1013 } 1014 1015 static void 1016 witness_ddb_display_list(int(*prnt)(const char *fmt, ...), 1017 struct witness_list *list) 1018 { 1019 struct witness *w; 1020 1021 STAILQ_FOREACH(w, list, w_typelist) { 1022 if (w->w_file == NULL || w->w_ddb_level > 0) 1023 continue; 1024 1025 /* This lock has no anscestors - display its descendants. */ 1026 witness_ddb_display_descendants(prnt, w, 0); 1027 if (db_pager_quit) 1028 return; 1029 } 1030 } 1031 1032 static void 1033 witness_ddb_display(int(*prnt)(const char *fmt, ...)) 1034 { 1035 struct witness *w; 1036 1037 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); 1038 witness_ddb_compute_levels(); 1039 1040 /* Clear all the displayed flags. */ 1041 STAILQ_FOREACH(w, &w_all, w_list) 1042 w->w_displayed = 0; 1043 1044 /* 1045 * First, handle sleep locks which have been acquired at least 1046 * once. 1047 */ 1048 prnt("Sleep locks:\n"); 1049 witness_ddb_display_list(prnt, &w_sleep); 1050 if (db_pager_quit) 1051 return; 1052 1053 /* 1054 * Now do spin locks which have been acquired at least once. 1055 */ 1056 prnt("\nSpin locks:\n"); 1057 witness_ddb_display_list(prnt, &w_spin); 1058 if (db_pager_quit) 1059 return; 1060 1061 /* 1062 * Finally, any locks which have not been acquired yet. 1063 */ 1064 prnt("\nLocks which were never acquired:\n"); 1065 STAILQ_FOREACH(w, &w_all, w_list) { 1066 if (w->w_file != NULL || w->w_refcount == 0) 1067 continue; 1068 prnt("%s (type: %s, depth: %d)\n", w->w_name, 1069 w->w_class->lc_name, w->w_ddb_level); 1070 if (db_pager_quit) 1071 return; 1072 } 1073 } 1074 #endif /* DDB */ 1075 1076 int 1077 witness_defineorder(struct lock_object *lock1, struct lock_object *lock2) 1078 { 1079 1080 if (witness_watch == -1 || KERNEL_PANICKED()) 1081 return (0); 1082 1083 /* Require locks that witness knows about. */ 1084 if (lock1 == NULL || lock1->lo_witness == NULL || lock2 == NULL || 1085 lock2->lo_witness == NULL) 1086 return (EINVAL); 1087 1088 mtx_assert(&w_mtx, MA_NOTOWNED); 1089 mtx_lock_spin(&w_mtx); 1090 1091 /* 1092 * If we already have either an explicit or implied lock order that 1093 * is the other way around, then return an error. 1094 */ 1095 if (witness_watch && 1096 isitmydescendant(lock2->lo_witness, lock1->lo_witness)) { 1097 mtx_unlock_spin(&w_mtx); 1098 return (EDOOFUS); 1099 } 1100 1101 /* Try to add the new order. */ 1102 CTR3(KTR_WITNESS, "%s: adding %s as a child of %s", __func__, 1103 lock2->lo_witness->w_name, lock1->lo_witness->w_name); 1104 itismychild(lock1->lo_witness, lock2->lo_witness); 1105 mtx_unlock_spin(&w_mtx); 1106 return (0); 1107 } 1108 1109 void 1110 witness_checkorder(struct lock_object *lock, int flags, const char *file, 1111 int line, struct lock_object *interlock) 1112 { 1113 struct lock_list_entry *lock_list, *lle; 1114 struct lock_instance *lock1, *lock2, *plock; 1115 struct lock_class *class, *iclass; 1116 struct witness *w, *w1; 1117 struct thread *td; 1118 int i, j; 1119 1120 if (witness_cold || witness_watch < 1 || lock->lo_witness == NULL || 1121 KERNEL_PANICKED()) 1122 return; 1123 1124 w = lock->lo_witness; 1125 class = LOCK_CLASS(lock); 1126 td = curthread; 1127 1128 if (class->lc_flags & LC_SLEEPLOCK) { 1129 1130 /* 1131 * Since spin locks include a critical section, this check 1132 * implicitly enforces a lock order of all sleep locks before 1133 * all spin locks. 1134 */ 1135 if (td->td_critnest != 0 && !kdb_active) 1136 kassert_panic("acquiring blockable sleep lock with " 1137 "spinlock or critical section held (%s) %s @ %s:%d", 1138 class->lc_name, lock->lo_name, 1139 fixup_filename(file), line); 1140 1141 /* 1142 * If this is the first lock acquired then just return as 1143 * no order checking is needed. 1144 */ 1145 lock_list = td->td_sleeplocks; 1146 if (lock_list == NULL || lock_list->ll_count == 0) 1147 return; 1148 } else { 1149 1150 /* 1151 * If this is the first lock, just return as no order 1152 * checking is needed. Avoid problems with thread 1153 * migration pinning the thread while checking if 1154 * spinlocks are held. If at least one spinlock is held 1155 * the thread is in a safe path and it is allowed to 1156 * unpin it. 1157 */ 1158 sched_pin(); 1159 lock_list = PCPU_GET(spinlocks); 1160 if (lock_list == NULL || lock_list->ll_count == 0) { 1161 sched_unpin(); 1162 return; 1163 } 1164 sched_unpin(); 1165 } 1166 1167 /* 1168 * Check to see if we are recursing on a lock we already own. If 1169 * so, make sure that we don't mismatch exclusive and shared lock 1170 * acquires. 1171 */ 1172 lock1 = find_instance(lock_list, lock); 1173 if (lock1 != NULL) { 1174 if ((lock1->li_flags & LI_EXCLUSIVE) != 0 && 1175 (flags & LOP_EXCLUSIVE) == 0) { 1176 witness_output("shared lock of (%s) %s @ %s:%d\n", 1177 class->lc_name, lock->lo_name, 1178 fixup_filename(file), line); 1179 witness_output("while exclusively locked from %s:%d\n", 1180 fixup_filename(lock1->li_file), lock1->li_line); 1181 kassert_panic("excl->share"); 1182 } 1183 if ((lock1->li_flags & LI_EXCLUSIVE) == 0 && 1184 (flags & LOP_EXCLUSIVE) != 0) { 1185 witness_output("exclusive lock of (%s) %s @ %s:%d\n", 1186 class->lc_name, lock->lo_name, 1187 fixup_filename(file), line); 1188 witness_output("while share locked from %s:%d\n", 1189 fixup_filename(lock1->li_file), lock1->li_line); 1190 kassert_panic("share->excl"); 1191 } 1192 return; 1193 } 1194 1195 /* Warn if the interlock is not locked exactly once. */ 1196 if (interlock != NULL) { 1197 iclass = LOCK_CLASS(interlock); 1198 lock1 = find_instance(lock_list, interlock); 1199 if (lock1 == NULL) 1200 kassert_panic("interlock (%s) %s not locked @ %s:%d", 1201 iclass->lc_name, interlock->lo_name, 1202 fixup_filename(file), line); 1203 else if ((lock1->li_flags & LI_RECURSEMASK) != 0) 1204 kassert_panic("interlock (%s) %s recursed @ %s:%d", 1205 iclass->lc_name, interlock->lo_name, 1206 fixup_filename(file), line); 1207 } 1208 1209 /* 1210 * Find the previously acquired lock, but ignore interlocks. 1211 */ 1212 plock = &lock_list->ll_children[lock_list->ll_count - 1]; 1213 if (interlock != NULL && plock->li_lock == interlock) { 1214 if (lock_list->ll_count > 1) 1215 plock = 1216 &lock_list->ll_children[lock_list->ll_count - 2]; 1217 else { 1218 lle = lock_list->ll_next; 1219 1220 /* 1221 * The interlock is the only lock we hold, so 1222 * simply return. 1223 */ 1224 if (lle == NULL) 1225 return; 1226 plock = &lle->ll_children[lle->ll_count - 1]; 1227 } 1228 } 1229 1230 /* 1231 * Try to perform most checks without a lock. If this succeeds we 1232 * can skip acquiring the lock and return success. Otherwise we redo 1233 * the check with the lock held to handle races with concurrent updates. 1234 */ 1235 w1 = plock->li_lock->lo_witness; 1236 if (witness_lock_order_check(w1, w)) 1237 return; 1238 1239 mtx_lock_spin(&w_mtx); 1240 if (witness_lock_order_check(w1, w)) { 1241 mtx_unlock_spin(&w_mtx); 1242 return; 1243 } 1244 witness_lock_order_add(w1, w); 1245 1246 /* 1247 * Check for duplicate locks of the same type. Note that we only 1248 * have to check for this on the last lock we just acquired. Any 1249 * other cases will be caught as lock order violations. 1250 */ 1251 if (w1 == w) { 1252 i = w->w_index; 1253 if (!(lock->lo_flags & LO_DUPOK) && !(flags & LOP_DUPOK) && 1254 !(w_rmatrix[i][i] & WITNESS_REVERSAL)) { 1255 w_rmatrix[i][i] |= WITNESS_REVERSAL; 1256 w->w_reversed = 1; 1257 mtx_unlock_spin(&w_mtx); 1258 witness_output( 1259 "acquiring duplicate lock of same type: \"%s\"\n", 1260 w->w_name); 1261 witness_output(" 1st %s @ %s:%d\n", plock->li_lock->lo_name, 1262 fixup_filename(plock->li_file), plock->li_line); 1263 witness_output(" 2nd %s @ %s:%d\n", lock->lo_name, 1264 fixup_filename(file), line); 1265 witness_debugger(1, __func__); 1266 } else 1267 mtx_unlock_spin(&w_mtx); 1268 return; 1269 } 1270 mtx_assert(&w_mtx, MA_OWNED); 1271 1272 /* 1273 * If we know that the lock we are acquiring comes after 1274 * the lock we most recently acquired in the lock order tree, 1275 * then there is no need for any further checks. 1276 */ 1277 if (isitmychild(w1, w)) 1278 goto out; 1279 1280 for (j = 0, lle = lock_list; lle != NULL; lle = lle->ll_next) { 1281 for (i = lle->ll_count - 1; i >= 0; i--, j++) { 1282 1283 MPASS(j < LOCK_CHILDCOUNT * LOCK_NCHILDREN); 1284 lock1 = &lle->ll_children[i]; 1285 1286 /* 1287 * Ignore the interlock. 1288 */ 1289 if (interlock == lock1->li_lock) 1290 continue; 1291 1292 /* 1293 * If this lock doesn't undergo witness checking, 1294 * then skip it. 1295 */ 1296 w1 = lock1->li_lock->lo_witness; 1297 if (w1 == NULL) { 1298 KASSERT((lock1->li_lock->lo_flags & LO_WITNESS) == 0, 1299 ("lock missing witness structure")); 1300 continue; 1301 } 1302 1303 /* 1304 * If we are locking Giant and this is a sleepable 1305 * lock, then skip it. 1306 */ 1307 if ((lock1->li_flags & LI_SLEEPABLE) != 0 && 1308 lock == &Giant.lock_object) 1309 continue; 1310 1311 /* 1312 * If we are locking a sleepable lock and this lock 1313 * is Giant, then skip it. 1314 */ 1315 if ((lock->lo_flags & LO_SLEEPABLE) != 0 && 1316 (flags & LOP_NOSLEEP) == 0 && 1317 lock1->li_lock == &Giant.lock_object) 1318 continue; 1319 1320 /* 1321 * If we are locking a sleepable lock and this lock 1322 * isn't sleepable, we want to treat it as a lock 1323 * order violation to enfore a general lock order of 1324 * sleepable locks before non-sleepable locks. 1325 */ 1326 if ((lock->lo_flags & LO_SLEEPABLE) != 0 && 1327 (flags & LOP_NOSLEEP) == 0 && 1328 (lock1->li_flags & LI_SLEEPABLE) == 0) 1329 goto reversal; 1330 1331 /* 1332 * If we are locking Giant and this is a non-sleepable 1333 * lock, then treat it as a reversal. 1334 */ 1335 if ((lock1->li_flags & LI_SLEEPABLE) == 0 && 1336 lock == &Giant.lock_object) 1337 goto reversal; 1338 1339 /* 1340 * Check the lock order hierarchy for a reveresal. 1341 */ 1342 if (!isitmydescendant(w, w1)) 1343 continue; 1344 reversal: 1345 1346 /* 1347 * We have a lock order violation, check to see if it 1348 * is allowed or has already been yelled about. 1349 */ 1350 1351 /* Bail if this violation is known */ 1352 if (w_rmatrix[w1->w_index][w->w_index] & WITNESS_REVERSAL) 1353 goto out; 1354 1355 /* Record this as a violation */ 1356 w_rmatrix[w1->w_index][w->w_index] |= WITNESS_REVERSAL; 1357 w_rmatrix[w->w_index][w1->w_index] |= WITNESS_REVERSAL; 1358 w->w_reversed = w1->w_reversed = 1; 1359 witness_increment_graph_generation(); 1360 1361 /* 1362 * If the lock order is blessed, bail before logging 1363 * anything. We don't look for other lock order 1364 * violations though, which may be a bug. 1365 */ 1366 if (blessed(w, w1)) 1367 goto out; 1368 mtx_unlock_spin(&w_mtx); 1369 1370 #ifdef WITNESS_NO_VNODE 1371 /* 1372 * There are known LORs between VNODE locks. They are 1373 * not an indication of a bug. VNODE locks are flagged 1374 * as such (LO_IS_VNODE) and we don't yell if the LOR 1375 * is between 2 VNODE locks. 1376 */ 1377 if ((lock->lo_flags & LO_IS_VNODE) != 0 && 1378 (lock1->li_lock->lo_flags & LO_IS_VNODE) != 0) 1379 return; 1380 #endif 1381 1382 /* 1383 * Ok, yell about it. 1384 */ 1385 if ((lock->lo_flags & LO_SLEEPABLE) != 0 && 1386 (flags & LOP_NOSLEEP) == 0 && 1387 (lock1->li_flags & LI_SLEEPABLE) == 0) 1388 witness_output( 1389 "lock order reversal: (sleepable after non-sleepable)\n"); 1390 else if ((lock1->li_flags & LI_SLEEPABLE) == 0 1391 && lock == &Giant.lock_object) 1392 witness_output( 1393 "lock order reversal: (Giant after non-sleepable)\n"); 1394 else 1395 witness_output("lock order reversal:\n"); 1396 1397 /* 1398 * Try to locate an earlier lock with 1399 * witness w in our list. 1400 */ 1401 do { 1402 lock2 = &lle->ll_children[i]; 1403 MPASS(lock2->li_lock != NULL); 1404 if (lock2->li_lock->lo_witness == w) 1405 break; 1406 if (i == 0 && lle->ll_next != NULL) { 1407 lle = lle->ll_next; 1408 i = lle->ll_count - 1; 1409 MPASS(i >= 0 && i < LOCK_NCHILDREN); 1410 } else 1411 i--; 1412 } while (i >= 0); 1413 if (i < 0) { 1414 witness_output(" 1st %p %s (%s) @ %s:%d\n", 1415 lock1->li_lock, lock1->li_lock->lo_name, 1416 w1->w_name, fixup_filename(lock1->li_file), 1417 lock1->li_line); 1418 witness_output(" 2nd %p %s (%s) @ %s:%d\n", lock, 1419 lock->lo_name, w->w_name, 1420 fixup_filename(file), line); 1421 } else { 1422 witness_output(" 1st %p %s (%s) @ %s:%d\n", 1423 lock2->li_lock, lock2->li_lock->lo_name, 1424 lock2->li_lock->lo_witness->w_name, 1425 fixup_filename(lock2->li_file), 1426 lock2->li_line); 1427 witness_output(" 2nd %p %s (%s) @ %s:%d\n", 1428 lock1->li_lock, lock1->li_lock->lo_name, 1429 w1->w_name, fixup_filename(lock1->li_file), 1430 lock1->li_line); 1431 witness_output(" 3rd %p %s (%s) @ %s:%d\n", lock, 1432 lock->lo_name, w->w_name, 1433 fixup_filename(file), line); 1434 } 1435 witness_debugger(1, __func__); 1436 return; 1437 } 1438 } 1439 1440 /* 1441 * If requested, build a new lock order. However, don't build a new 1442 * relationship between a sleepable lock and Giant if it is in the 1443 * wrong direction. The correct lock order is that sleepable locks 1444 * always come before Giant. 1445 */ 1446 if (flags & LOP_NEWORDER && 1447 !(plock->li_lock == &Giant.lock_object && 1448 (lock->lo_flags & LO_SLEEPABLE) != 0 && 1449 (flags & LOP_NOSLEEP) == 0)) { 1450 CTR3(KTR_WITNESS, "%s: adding %s as a child of %s", __func__, 1451 w->w_name, plock->li_lock->lo_witness->w_name); 1452 itismychild(plock->li_lock->lo_witness, w); 1453 } 1454 out: 1455 mtx_unlock_spin(&w_mtx); 1456 } 1457 1458 void 1459 witness_lock(struct lock_object *lock, int flags, const char *file, int line) 1460 { 1461 struct lock_list_entry **lock_list, *lle; 1462 struct lock_instance *instance; 1463 struct witness *w; 1464 struct thread *td; 1465 1466 if (witness_cold || witness_watch == -1 || lock->lo_witness == NULL || 1467 KERNEL_PANICKED()) 1468 return; 1469 w = lock->lo_witness; 1470 td = curthread; 1471 1472 /* Determine lock list for this lock. */ 1473 if (LOCK_CLASS(lock)->lc_flags & LC_SLEEPLOCK) 1474 lock_list = &td->td_sleeplocks; 1475 else 1476 lock_list = PCPU_PTR(spinlocks); 1477 1478 /* Check to see if we are recursing on a lock we already own. */ 1479 instance = find_instance(*lock_list, lock); 1480 if (instance != NULL) { 1481 instance->li_flags++; 1482 CTR4(KTR_WITNESS, "%s: pid %d recursed on %s r=%d", __func__, 1483 td->td_proc->p_pid, lock->lo_name, 1484 instance->li_flags & LI_RECURSEMASK); 1485 instance->li_file = file; 1486 instance->li_line = line; 1487 return; 1488 } 1489 1490 /* Update per-witness last file and line acquire. */ 1491 w->w_file = file; 1492 w->w_line = line; 1493 1494 /* Find the next open lock instance in the list and fill it. */ 1495 lle = *lock_list; 1496 if (lle == NULL || lle->ll_count == LOCK_NCHILDREN) { 1497 lle = witness_lock_list_get(); 1498 if (lle == NULL) 1499 return; 1500 lle->ll_next = *lock_list; 1501 CTR3(KTR_WITNESS, "%s: pid %d added lle %p", __func__, 1502 td->td_proc->p_pid, lle); 1503 *lock_list = lle; 1504 } 1505 instance = &lle->ll_children[lle->ll_count++]; 1506 instance->li_lock = lock; 1507 instance->li_line = line; 1508 instance->li_file = file; 1509 instance->li_flags = 0; 1510 if ((flags & LOP_EXCLUSIVE) != 0) 1511 instance->li_flags |= LI_EXCLUSIVE; 1512 if ((lock->lo_flags & LO_SLEEPABLE) != 0 && (flags & LOP_NOSLEEP) == 0) 1513 instance->li_flags |= LI_SLEEPABLE; 1514 CTR4(KTR_WITNESS, "%s: pid %d added %s as lle[%d]", __func__, 1515 td->td_proc->p_pid, lock->lo_name, lle->ll_count - 1); 1516 } 1517 1518 void 1519 witness_upgrade(struct lock_object *lock, int flags, const char *file, int line) 1520 { 1521 struct lock_instance *instance; 1522 struct lock_class *class; 1523 1524 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); 1525 if (lock->lo_witness == NULL || witness_watch == -1 || KERNEL_PANICKED()) 1526 return; 1527 class = LOCK_CLASS(lock); 1528 if (witness_watch) { 1529 if ((lock->lo_flags & LO_UPGRADABLE) == 0) 1530 kassert_panic( 1531 "upgrade of non-upgradable lock (%s) %s @ %s:%d", 1532 class->lc_name, lock->lo_name, 1533 fixup_filename(file), line); 1534 if ((class->lc_flags & LC_SLEEPLOCK) == 0) 1535 kassert_panic( 1536 "upgrade of non-sleep lock (%s) %s @ %s:%d", 1537 class->lc_name, lock->lo_name, 1538 fixup_filename(file), line); 1539 } 1540 instance = find_instance(curthread->td_sleeplocks, lock); 1541 if (instance == NULL) { 1542 kassert_panic("upgrade of unlocked lock (%s) %s @ %s:%d", 1543 class->lc_name, lock->lo_name, 1544 fixup_filename(file), line); 1545 return; 1546 } 1547 if (witness_watch) { 1548 if ((instance->li_flags & LI_EXCLUSIVE) != 0) 1549 kassert_panic( 1550 "upgrade of exclusive lock (%s) %s @ %s:%d", 1551 class->lc_name, lock->lo_name, 1552 fixup_filename(file), line); 1553 if ((instance->li_flags & LI_RECURSEMASK) != 0) 1554 kassert_panic( 1555 "upgrade of recursed lock (%s) %s r=%d @ %s:%d", 1556 class->lc_name, lock->lo_name, 1557 instance->li_flags & LI_RECURSEMASK, 1558 fixup_filename(file), line); 1559 } 1560 instance->li_flags |= LI_EXCLUSIVE; 1561 } 1562 1563 void 1564 witness_downgrade(struct lock_object *lock, int flags, const char *file, 1565 int line) 1566 { 1567 struct lock_instance *instance; 1568 struct lock_class *class; 1569 1570 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); 1571 if (lock->lo_witness == NULL || witness_watch == -1 || KERNEL_PANICKED()) 1572 return; 1573 class = LOCK_CLASS(lock); 1574 if (witness_watch) { 1575 if ((lock->lo_flags & LO_UPGRADABLE) == 0) 1576 kassert_panic( 1577 "downgrade of non-upgradable lock (%s) %s @ %s:%d", 1578 class->lc_name, lock->lo_name, 1579 fixup_filename(file), line); 1580 if ((class->lc_flags & LC_SLEEPLOCK) == 0) 1581 kassert_panic( 1582 "downgrade of non-sleep lock (%s) %s @ %s:%d", 1583 class->lc_name, lock->lo_name, 1584 fixup_filename(file), line); 1585 } 1586 instance = find_instance(curthread->td_sleeplocks, lock); 1587 if (instance == NULL) { 1588 kassert_panic("downgrade of unlocked lock (%s) %s @ %s:%d", 1589 class->lc_name, lock->lo_name, 1590 fixup_filename(file), line); 1591 return; 1592 } 1593 if (witness_watch) { 1594 if ((instance->li_flags & LI_EXCLUSIVE) == 0) 1595 kassert_panic( 1596 "downgrade of shared lock (%s) %s @ %s:%d", 1597 class->lc_name, lock->lo_name, 1598 fixup_filename(file), line); 1599 if ((instance->li_flags & LI_RECURSEMASK) != 0) 1600 kassert_panic( 1601 "downgrade of recursed lock (%s) %s r=%d @ %s:%d", 1602 class->lc_name, lock->lo_name, 1603 instance->li_flags & LI_RECURSEMASK, 1604 fixup_filename(file), line); 1605 } 1606 instance->li_flags &= ~LI_EXCLUSIVE; 1607 } 1608 1609 void 1610 witness_unlock(struct lock_object *lock, int flags, const char *file, int line) 1611 { 1612 struct lock_list_entry **lock_list, *lle; 1613 struct lock_instance *instance; 1614 struct lock_class *class; 1615 struct thread *td; 1616 register_t s; 1617 int i, j; 1618 1619 if (witness_cold || lock->lo_witness == NULL || KERNEL_PANICKED()) 1620 return; 1621 td = curthread; 1622 class = LOCK_CLASS(lock); 1623 1624 /* Find lock instance associated with this lock. */ 1625 if (class->lc_flags & LC_SLEEPLOCK) 1626 lock_list = &td->td_sleeplocks; 1627 else 1628 lock_list = PCPU_PTR(spinlocks); 1629 lle = *lock_list; 1630 for (; *lock_list != NULL; lock_list = &(*lock_list)->ll_next) 1631 for (i = 0; i < (*lock_list)->ll_count; i++) { 1632 instance = &(*lock_list)->ll_children[i]; 1633 if (instance->li_lock == lock) 1634 goto found; 1635 } 1636 1637 /* 1638 * When disabling WITNESS through witness_watch we could end up in 1639 * having registered locks in the td_sleeplocks queue. 1640 * We have to make sure we flush these queues, so just search for 1641 * eventual register locks and remove them. 1642 */ 1643 if (witness_watch > 0) { 1644 kassert_panic("lock (%s) %s not locked @ %s:%d", class->lc_name, 1645 lock->lo_name, fixup_filename(file), line); 1646 return; 1647 } else { 1648 return; 1649 } 1650 found: 1651 1652 /* First, check for shared/exclusive mismatches. */ 1653 if ((instance->li_flags & LI_EXCLUSIVE) != 0 && witness_watch > 0 && 1654 (flags & LOP_EXCLUSIVE) == 0) { 1655 witness_output("shared unlock of (%s) %s @ %s:%d\n", 1656 class->lc_name, lock->lo_name, fixup_filename(file), line); 1657 witness_output("while exclusively locked from %s:%d\n", 1658 fixup_filename(instance->li_file), instance->li_line); 1659 kassert_panic("excl->ushare"); 1660 } 1661 if ((instance->li_flags & LI_EXCLUSIVE) == 0 && witness_watch > 0 && 1662 (flags & LOP_EXCLUSIVE) != 0) { 1663 witness_output("exclusive unlock of (%s) %s @ %s:%d\n", 1664 class->lc_name, lock->lo_name, fixup_filename(file), line); 1665 witness_output("while share locked from %s:%d\n", 1666 fixup_filename(instance->li_file), 1667 instance->li_line); 1668 kassert_panic("share->uexcl"); 1669 } 1670 /* If we are recursed, unrecurse. */ 1671 if ((instance->li_flags & LI_RECURSEMASK) > 0) { 1672 CTR4(KTR_WITNESS, "%s: pid %d unrecursed on %s r=%d", __func__, 1673 td->td_proc->p_pid, instance->li_lock->lo_name, 1674 instance->li_flags); 1675 instance->li_flags--; 1676 return; 1677 } 1678 /* The lock is now being dropped, check for NORELEASE flag */ 1679 if ((instance->li_flags & LI_NORELEASE) != 0 && witness_watch > 0) { 1680 witness_output("forbidden unlock of (%s) %s @ %s:%d\n", 1681 class->lc_name, lock->lo_name, fixup_filename(file), line); 1682 kassert_panic("lock marked norelease"); 1683 } 1684 1685 /* Otherwise, remove this item from the list. */ 1686 s = intr_disable(); 1687 CTR4(KTR_WITNESS, "%s: pid %d removed %s from lle[%d]", __func__, 1688 td->td_proc->p_pid, instance->li_lock->lo_name, 1689 (*lock_list)->ll_count - 1); 1690 for (j = i; j < (*lock_list)->ll_count - 1; j++) 1691 (*lock_list)->ll_children[j] = 1692 (*lock_list)->ll_children[j + 1]; 1693 (*lock_list)->ll_count--; 1694 intr_restore(s); 1695 1696 /* 1697 * In order to reduce contention on w_mtx, we want to keep always an 1698 * head object into lists so that frequent allocation from the 1699 * free witness pool (and subsequent locking) is avoided. 1700 * In order to maintain the current code simple, when the head 1701 * object is totally unloaded it means also that we do not have 1702 * further objects in the list, so the list ownership needs to be 1703 * hand over to another object if the current head needs to be freed. 1704 */ 1705 if ((*lock_list)->ll_count == 0) { 1706 if (*lock_list == lle) { 1707 if (lle->ll_next == NULL) 1708 return; 1709 } else 1710 lle = *lock_list; 1711 *lock_list = lle->ll_next; 1712 CTR3(KTR_WITNESS, "%s: pid %d removed lle %p", __func__, 1713 td->td_proc->p_pid, lle); 1714 witness_lock_list_free(lle); 1715 } 1716 } 1717 1718 void 1719 witness_thread_exit(struct thread *td) 1720 { 1721 struct lock_list_entry *lle; 1722 int i, n; 1723 1724 lle = td->td_sleeplocks; 1725 if (lle == NULL || KERNEL_PANICKED()) 1726 return; 1727 if (lle->ll_count != 0) { 1728 for (n = 0; lle != NULL; lle = lle->ll_next) 1729 for (i = lle->ll_count - 1; i >= 0; i--) { 1730 if (n == 0) 1731 witness_output( 1732 "Thread %p exiting with the following locks held:\n", td); 1733 n++; 1734 witness_list_lock(&lle->ll_children[i], 1735 witness_output); 1736 1737 } 1738 kassert_panic( 1739 "Thread %p cannot exit while holding sleeplocks\n", td); 1740 } 1741 witness_lock_list_free(lle); 1742 } 1743 1744 /* 1745 * Warn if any locks other than 'lock' are held. Flags can be passed in to 1746 * exempt Giant and sleepable locks from the checks as well. If any 1747 * non-exempt locks are held, then a supplied message is printed to the 1748 * output channel along with a list of the offending locks. If indicated in the 1749 * flags then a failure results in a panic as well. 1750 */ 1751 int 1752 witness_warn(int flags, struct lock_object *lock, const char *fmt, ...) 1753 { 1754 struct lock_list_entry *lock_list, *lle; 1755 struct lock_instance *lock1; 1756 struct thread *td; 1757 va_list ap; 1758 int i, n; 1759 1760 if (witness_cold || witness_watch < 1 || KERNEL_PANICKED()) 1761 return (0); 1762 n = 0; 1763 td = curthread; 1764 for (lle = td->td_sleeplocks; lle != NULL; lle = lle->ll_next) 1765 for (i = lle->ll_count - 1; i >= 0; i--) { 1766 lock1 = &lle->ll_children[i]; 1767 if (lock1->li_lock == lock) 1768 continue; 1769 if (flags & WARN_GIANTOK && 1770 lock1->li_lock == &Giant.lock_object) 1771 continue; 1772 if (flags & WARN_SLEEPOK && 1773 (lock1->li_flags & LI_SLEEPABLE) != 0) 1774 continue; 1775 if (n == 0) { 1776 va_start(ap, fmt); 1777 vprintf(fmt, ap); 1778 va_end(ap); 1779 printf(" with the following %slocks held:\n", 1780 (flags & WARN_SLEEPOK) != 0 ? 1781 "non-sleepable " : ""); 1782 } 1783 n++; 1784 witness_list_lock(lock1, printf); 1785 } 1786 1787 /* 1788 * Pin the thread in order to avoid problems with thread migration. 1789 * Once that all verifies are passed about spinlocks ownership, 1790 * the thread is in a safe path and it can be unpinned. 1791 */ 1792 sched_pin(); 1793 lock_list = PCPU_GET(spinlocks); 1794 if (lock_list != NULL && lock_list->ll_count != 0) { 1795 sched_unpin(); 1796 1797 /* 1798 * We should only have one spinlock and as long as 1799 * the flags cannot match for this locks class, 1800 * check if the first spinlock is the one curthread 1801 * should hold. 1802 */ 1803 lock1 = &lock_list->ll_children[lock_list->ll_count - 1]; 1804 if (lock_list->ll_count == 1 && lock_list->ll_next == NULL && 1805 lock1->li_lock == lock && n == 0) 1806 return (0); 1807 1808 va_start(ap, fmt); 1809 vprintf(fmt, ap); 1810 va_end(ap); 1811 printf(" with the following %slocks held:\n", 1812 (flags & WARN_SLEEPOK) != 0 ? "non-sleepable " : ""); 1813 n += witness_list_locks(&lock_list, printf); 1814 } else 1815 sched_unpin(); 1816 if (flags & WARN_PANIC && n) 1817 kassert_panic("%s", __func__); 1818 else 1819 witness_debugger(n, __func__); 1820 return (n); 1821 } 1822 1823 const char * 1824 witness_file(struct lock_object *lock) 1825 { 1826 struct witness *w; 1827 1828 if (witness_cold || witness_watch < 1 || lock->lo_witness == NULL) 1829 return ("?"); 1830 w = lock->lo_witness; 1831 return (w->w_file); 1832 } 1833 1834 int 1835 witness_line(struct lock_object *lock) 1836 { 1837 struct witness *w; 1838 1839 if (witness_cold || witness_watch < 1 || lock->lo_witness == NULL) 1840 return (0); 1841 w = lock->lo_witness; 1842 return (w->w_line); 1843 } 1844 1845 static struct witness * 1846 enroll(const char *description, struct lock_class *lock_class) 1847 { 1848 struct witness *w; 1849 1850 MPASS(description != NULL); 1851 1852 if (witness_watch == -1 || KERNEL_PANICKED()) 1853 return (NULL); 1854 if ((lock_class->lc_flags & LC_SPINLOCK)) { 1855 if (witness_skipspin) 1856 return (NULL); 1857 } else if ((lock_class->lc_flags & LC_SLEEPLOCK) == 0) { 1858 kassert_panic("lock class %s is not sleep or spin", 1859 lock_class->lc_name); 1860 return (NULL); 1861 } 1862 1863 mtx_lock_spin(&w_mtx); 1864 w = witness_hash_get(description); 1865 if (w) 1866 goto found; 1867 if ((w = witness_get()) == NULL) 1868 return (NULL); 1869 MPASS(strlen(description) < MAX_W_NAME); 1870 strcpy(w->w_name, description); 1871 w->w_class = lock_class; 1872 w->w_refcount = 1; 1873 STAILQ_INSERT_HEAD(&w_all, w, w_list); 1874 if (lock_class->lc_flags & LC_SPINLOCK) { 1875 STAILQ_INSERT_HEAD(&w_spin, w, w_typelist); 1876 w_spin_cnt++; 1877 } else if (lock_class->lc_flags & LC_SLEEPLOCK) { 1878 STAILQ_INSERT_HEAD(&w_sleep, w, w_typelist); 1879 w_sleep_cnt++; 1880 } 1881 1882 /* Insert new witness into the hash */ 1883 witness_hash_put(w); 1884 witness_increment_graph_generation(); 1885 mtx_unlock_spin(&w_mtx); 1886 return (w); 1887 found: 1888 w->w_refcount++; 1889 if (w->w_refcount == 1) 1890 w->w_class = lock_class; 1891 mtx_unlock_spin(&w_mtx); 1892 if (lock_class != w->w_class) 1893 kassert_panic( 1894 "lock (%s) %s does not match earlier (%s) lock", 1895 description, lock_class->lc_name, 1896 w->w_class->lc_name); 1897 return (w); 1898 } 1899 1900 static void 1901 depart(struct witness *w) 1902 { 1903 1904 MPASS(w->w_refcount == 0); 1905 if (w->w_class->lc_flags & LC_SLEEPLOCK) { 1906 w_sleep_cnt--; 1907 } else { 1908 w_spin_cnt--; 1909 } 1910 /* 1911 * Set file to NULL as it may point into a loadable module. 1912 */ 1913 w->w_file = NULL; 1914 w->w_line = 0; 1915 witness_increment_graph_generation(); 1916 } 1917 1918 1919 static void 1920 adopt(struct witness *parent, struct witness *child) 1921 { 1922 int pi, ci, i, j; 1923 1924 if (witness_cold == 0) 1925 mtx_assert(&w_mtx, MA_OWNED); 1926 1927 /* If the relationship is already known, there's no work to be done. */ 1928 if (isitmychild(parent, child)) 1929 return; 1930 1931 /* When the structure of the graph changes, bump up the generation. */ 1932 witness_increment_graph_generation(); 1933 1934 /* 1935 * The hard part ... create the direct relationship, then propagate all 1936 * indirect relationships. 1937 */ 1938 pi = parent->w_index; 1939 ci = child->w_index; 1940 WITNESS_INDEX_ASSERT(pi); 1941 WITNESS_INDEX_ASSERT(ci); 1942 MPASS(pi != ci); 1943 w_rmatrix[pi][ci] |= WITNESS_PARENT; 1944 w_rmatrix[ci][pi] |= WITNESS_CHILD; 1945 1946 /* 1947 * If parent was not already an ancestor of child, 1948 * then we increment the descendant and ancestor counters. 1949 */ 1950 if ((w_rmatrix[pi][ci] & WITNESS_ANCESTOR) == 0) { 1951 parent->w_num_descendants++; 1952 child->w_num_ancestors++; 1953 } 1954 1955 /* 1956 * Find each ancestor of 'pi'. Note that 'pi' itself is counted as 1957 * an ancestor of 'pi' during this loop. 1958 */ 1959 for (i = 1; i <= w_max_used_index; i++) { 1960 if ((w_rmatrix[i][pi] & WITNESS_ANCESTOR_MASK) == 0 && 1961 (i != pi)) 1962 continue; 1963 1964 /* Find each descendant of 'i' and mark it as a descendant. */ 1965 for (j = 1; j <= w_max_used_index; j++) { 1966 1967 /* 1968 * Skip children that are already marked as 1969 * descendants of 'i'. 1970 */ 1971 if (w_rmatrix[i][j] & WITNESS_ANCESTOR_MASK) 1972 continue; 1973 1974 /* 1975 * We are only interested in descendants of 'ci'. Note 1976 * that 'ci' itself is counted as a descendant of 'ci'. 1977 */ 1978 if ((w_rmatrix[ci][j] & WITNESS_ANCESTOR_MASK) == 0 && 1979 (j != ci)) 1980 continue; 1981 w_rmatrix[i][j] |= WITNESS_ANCESTOR; 1982 w_rmatrix[j][i] |= WITNESS_DESCENDANT; 1983 w_data[i].w_num_descendants++; 1984 w_data[j].w_num_ancestors++; 1985 1986 /* 1987 * Make sure we aren't marking a node as both an 1988 * ancestor and descendant. We should have caught 1989 * this as a lock order reversal earlier. 1990 */ 1991 if ((w_rmatrix[i][j] & WITNESS_ANCESTOR_MASK) && 1992 (w_rmatrix[i][j] & WITNESS_DESCENDANT_MASK)) { 1993 printf("witness rmatrix paradox! [%d][%d]=%d " 1994 "both ancestor and descendant\n", 1995 i, j, w_rmatrix[i][j]); 1996 kdb_backtrace(); 1997 printf("Witness disabled.\n"); 1998 witness_watch = -1; 1999 } 2000 if ((w_rmatrix[j][i] & WITNESS_ANCESTOR_MASK) && 2001 (w_rmatrix[j][i] & WITNESS_DESCENDANT_MASK)) { 2002 printf("witness rmatrix paradox! [%d][%d]=%d " 2003 "both ancestor and descendant\n", 2004 j, i, w_rmatrix[j][i]); 2005 kdb_backtrace(); 2006 printf("Witness disabled.\n"); 2007 witness_watch = -1; 2008 } 2009 } 2010 } 2011 } 2012 2013 static void 2014 itismychild(struct witness *parent, struct witness *child) 2015 { 2016 int unlocked; 2017 2018 MPASS(child != NULL && parent != NULL); 2019 if (witness_cold == 0) 2020 mtx_assert(&w_mtx, MA_OWNED); 2021 2022 if (!witness_lock_type_equal(parent, child)) { 2023 if (witness_cold == 0) { 2024 unlocked = 1; 2025 mtx_unlock_spin(&w_mtx); 2026 } else { 2027 unlocked = 0; 2028 } 2029 kassert_panic( 2030 "%s: parent \"%s\" (%s) and child \"%s\" (%s) are not " 2031 "the same lock type", __func__, parent->w_name, 2032 parent->w_class->lc_name, child->w_name, 2033 child->w_class->lc_name); 2034 if (unlocked) 2035 mtx_lock_spin(&w_mtx); 2036 } 2037 adopt(parent, child); 2038 } 2039 2040 /* 2041 * Generic code for the isitmy*() functions. The rmask parameter is the 2042 * expected relationship of w1 to w2. 2043 */ 2044 static int 2045 _isitmyx(struct witness *w1, struct witness *w2, int rmask, const char *fname) 2046 { 2047 unsigned char r1, r2; 2048 int i1, i2; 2049 2050 i1 = w1->w_index; 2051 i2 = w2->w_index; 2052 WITNESS_INDEX_ASSERT(i1); 2053 WITNESS_INDEX_ASSERT(i2); 2054 r1 = w_rmatrix[i1][i2] & WITNESS_RELATED_MASK; 2055 r2 = w_rmatrix[i2][i1] & WITNESS_RELATED_MASK; 2056 2057 /* The flags on one better be the inverse of the flags on the other */ 2058 if (!((WITNESS_ATOD(r1) == r2 && WITNESS_DTOA(r2) == r1) || 2059 (WITNESS_DTOA(r1) == r2 && WITNESS_ATOD(r2) == r1))) { 2060 /* Don't squawk if we're potentially racing with an update. */ 2061 if (!mtx_owned(&w_mtx)) 2062 return (0); 2063 printf("%s: rmatrix mismatch between %s (index %d) and %s " 2064 "(index %d): w_rmatrix[%d][%d] == %hhx but " 2065 "w_rmatrix[%d][%d] == %hhx\n", 2066 fname, w1->w_name, i1, w2->w_name, i2, i1, i2, r1, 2067 i2, i1, r2); 2068 kdb_backtrace(); 2069 printf("Witness disabled.\n"); 2070 witness_watch = -1; 2071 } 2072 return (r1 & rmask); 2073 } 2074 2075 /* 2076 * Checks if @child is a direct child of @parent. 2077 */ 2078 static int 2079 isitmychild(struct witness *parent, struct witness *child) 2080 { 2081 2082 return (_isitmyx(parent, child, WITNESS_PARENT, __func__)); 2083 } 2084 2085 /* 2086 * Checks if @descendant is a direct or inderect descendant of @ancestor. 2087 */ 2088 static int 2089 isitmydescendant(struct witness *ancestor, struct witness *descendant) 2090 { 2091 2092 return (_isitmyx(ancestor, descendant, WITNESS_ANCESTOR_MASK, 2093 __func__)); 2094 } 2095 2096 static int 2097 blessed(struct witness *w1, struct witness *w2) 2098 { 2099 int i; 2100 struct witness_blessed *b; 2101 2102 for (i = 0; i < nitems(blessed_list); i++) { 2103 b = &blessed_list[i]; 2104 if (strcmp(w1->w_name, b->b_lock1) == 0) { 2105 if (strcmp(w2->w_name, b->b_lock2) == 0) 2106 return (1); 2107 continue; 2108 } 2109 if (strcmp(w1->w_name, b->b_lock2) == 0) 2110 if (strcmp(w2->w_name, b->b_lock1) == 0) 2111 return (1); 2112 } 2113 return (0); 2114 } 2115 2116 static struct witness * 2117 witness_get(void) 2118 { 2119 struct witness *w; 2120 int index; 2121 2122 if (witness_cold == 0) 2123 mtx_assert(&w_mtx, MA_OWNED); 2124 2125 if (witness_watch == -1) { 2126 mtx_unlock_spin(&w_mtx); 2127 return (NULL); 2128 } 2129 if (STAILQ_EMPTY(&w_free)) { 2130 witness_watch = -1; 2131 mtx_unlock_spin(&w_mtx); 2132 printf("WITNESS: unable to allocate a new witness object\n"); 2133 return (NULL); 2134 } 2135 w = STAILQ_FIRST(&w_free); 2136 STAILQ_REMOVE_HEAD(&w_free, w_list); 2137 w_free_cnt--; 2138 index = w->w_index; 2139 MPASS(index > 0 && index == w_max_used_index+1 && 2140 index < witness_count); 2141 bzero(w, sizeof(*w)); 2142 w->w_index = index; 2143 if (index > w_max_used_index) 2144 w_max_used_index = index; 2145 return (w); 2146 } 2147 2148 static void 2149 witness_free(struct witness *w) 2150 { 2151 2152 STAILQ_INSERT_HEAD(&w_free, w, w_list); 2153 w_free_cnt++; 2154 } 2155 2156 static struct lock_list_entry * 2157 witness_lock_list_get(void) 2158 { 2159 struct lock_list_entry *lle; 2160 2161 if (witness_watch == -1) 2162 return (NULL); 2163 mtx_lock_spin(&w_mtx); 2164 lle = w_lock_list_free; 2165 if (lle == NULL) { 2166 witness_watch = -1; 2167 mtx_unlock_spin(&w_mtx); 2168 printf("%s: witness exhausted\n", __func__); 2169 return (NULL); 2170 } 2171 w_lock_list_free = lle->ll_next; 2172 mtx_unlock_spin(&w_mtx); 2173 bzero(lle, sizeof(*lle)); 2174 return (lle); 2175 } 2176 2177 static void 2178 witness_lock_list_free(struct lock_list_entry *lle) 2179 { 2180 2181 mtx_lock_spin(&w_mtx); 2182 lle->ll_next = w_lock_list_free; 2183 w_lock_list_free = lle; 2184 mtx_unlock_spin(&w_mtx); 2185 } 2186 2187 static struct lock_instance * 2188 find_instance(struct lock_list_entry *list, const struct lock_object *lock) 2189 { 2190 struct lock_list_entry *lle; 2191 struct lock_instance *instance; 2192 int i; 2193 2194 for (lle = list; lle != NULL; lle = lle->ll_next) 2195 for (i = lle->ll_count - 1; i >= 0; i--) { 2196 instance = &lle->ll_children[i]; 2197 if (instance->li_lock == lock) 2198 return (instance); 2199 } 2200 return (NULL); 2201 } 2202 2203 static void 2204 witness_list_lock(struct lock_instance *instance, 2205 int (*prnt)(const char *fmt, ...)) 2206 { 2207 struct lock_object *lock; 2208 2209 lock = instance->li_lock; 2210 prnt("%s %s %s", (instance->li_flags & LI_EXCLUSIVE) != 0 ? 2211 "exclusive" : "shared", LOCK_CLASS(lock)->lc_name, lock->lo_name); 2212 if (lock->lo_witness->w_name != lock->lo_name) 2213 prnt(" (%s)", lock->lo_witness->w_name); 2214 prnt(" r = %d (%p) locked @ %s:%d\n", 2215 instance->li_flags & LI_RECURSEMASK, lock, 2216 fixup_filename(instance->li_file), instance->li_line); 2217 } 2218 2219 static int 2220 witness_output(const char *fmt, ...) 2221 { 2222 va_list ap; 2223 int ret; 2224 2225 va_start(ap, fmt); 2226 ret = witness_voutput(fmt, ap); 2227 va_end(ap); 2228 return (ret); 2229 } 2230 2231 static int 2232 witness_voutput(const char *fmt, va_list ap) 2233 { 2234 int ret; 2235 2236 ret = 0; 2237 switch (witness_channel) { 2238 case WITNESS_CONSOLE: 2239 ret = vprintf(fmt, ap); 2240 break; 2241 case WITNESS_LOG: 2242 vlog(LOG_NOTICE, fmt, ap); 2243 break; 2244 case WITNESS_NONE: 2245 break; 2246 } 2247 return (ret); 2248 } 2249 2250 #ifdef DDB 2251 static int 2252 witness_thread_has_locks(struct thread *td) 2253 { 2254 2255 if (td->td_sleeplocks == NULL) 2256 return (0); 2257 return (td->td_sleeplocks->ll_count != 0); 2258 } 2259 2260 static int 2261 witness_proc_has_locks(struct proc *p) 2262 { 2263 struct thread *td; 2264 2265 FOREACH_THREAD_IN_PROC(p, td) { 2266 if (witness_thread_has_locks(td)) 2267 return (1); 2268 } 2269 return (0); 2270 } 2271 #endif 2272 2273 int 2274 witness_list_locks(struct lock_list_entry **lock_list, 2275 int (*prnt)(const char *fmt, ...)) 2276 { 2277 struct lock_list_entry *lle; 2278 int i, nheld; 2279 2280 nheld = 0; 2281 for (lle = *lock_list; lle != NULL; lle = lle->ll_next) 2282 for (i = lle->ll_count - 1; i >= 0; i--) { 2283 witness_list_lock(&lle->ll_children[i], prnt); 2284 nheld++; 2285 } 2286 return (nheld); 2287 } 2288 2289 /* 2290 * This is a bit risky at best. We call this function when we have timed 2291 * out acquiring a spin lock, and we assume that the other CPU is stuck 2292 * with this lock held. So, we go groveling around in the other CPU's 2293 * per-cpu data to try to find the lock instance for this spin lock to 2294 * see when it was last acquired. 2295 */ 2296 void 2297 witness_display_spinlock(struct lock_object *lock, struct thread *owner, 2298 int (*prnt)(const char *fmt, ...)) 2299 { 2300 struct lock_instance *instance; 2301 struct pcpu *pc; 2302 2303 if (owner->td_critnest == 0 || owner->td_oncpu == NOCPU) 2304 return; 2305 pc = pcpu_find(owner->td_oncpu); 2306 instance = find_instance(pc->pc_spinlocks, lock); 2307 if (instance != NULL) 2308 witness_list_lock(instance, prnt); 2309 } 2310 2311 void 2312 witness_save(struct lock_object *lock, const char **filep, int *linep) 2313 { 2314 struct lock_list_entry *lock_list; 2315 struct lock_instance *instance; 2316 struct lock_class *class; 2317 2318 /* 2319 * This function is used independently in locking code to deal with 2320 * Giant, SCHEDULER_STOPPED() check can be removed here after Giant 2321 * is gone. 2322 */ 2323 if (SCHEDULER_STOPPED()) 2324 return; 2325 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); 2326 if (lock->lo_witness == NULL || witness_watch == -1 || KERNEL_PANICKED()) 2327 return; 2328 class = LOCK_CLASS(lock); 2329 if (class->lc_flags & LC_SLEEPLOCK) 2330 lock_list = curthread->td_sleeplocks; 2331 else { 2332 if (witness_skipspin) 2333 return; 2334 lock_list = PCPU_GET(spinlocks); 2335 } 2336 instance = find_instance(lock_list, lock); 2337 if (instance == NULL) { 2338 kassert_panic("%s: lock (%s) %s not locked", __func__, 2339 class->lc_name, lock->lo_name); 2340 return; 2341 } 2342 *filep = instance->li_file; 2343 *linep = instance->li_line; 2344 } 2345 2346 void 2347 witness_restore(struct lock_object *lock, const char *file, int line) 2348 { 2349 struct lock_list_entry *lock_list; 2350 struct lock_instance *instance; 2351 struct lock_class *class; 2352 2353 /* 2354 * This function is used independently in locking code to deal with 2355 * Giant, SCHEDULER_STOPPED() check can be removed here after Giant 2356 * is gone. 2357 */ 2358 if (SCHEDULER_STOPPED()) 2359 return; 2360 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); 2361 if (lock->lo_witness == NULL || witness_watch == -1 || KERNEL_PANICKED()) 2362 return; 2363 class = LOCK_CLASS(lock); 2364 if (class->lc_flags & LC_SLEEPLOCK) 2365 lock_list = curthread->td_sleeplocks; 2366 else { 2367 if (witness_skipspin) 2368 return; 2369 lock_list = PCPU_GET(spinlocks); 2370 } 2371 instance = find_instance(lock_list, lock); 2372 if (instance == NULL) 2373 kassert_panic("%s: lock (%s) %s not locked", __func__, 2374 class->lc_name, lock->lo_name); 2375 lock->lo_witness->w_file = file; 2376 lock->lo_witness->w_line = line; 2377 if (instance == NULL) 2378 return; 2379 instance->li_file = file; 2380 instance->li_line = line; 2381 } 2382 2383 void 2384 witness_assert(const struct lock_object *lock, int flags, const char *file, 2385 int line) 2386 { 2387 #ifdef INVARIANT_SUPPORT 2388 struct lock_instance *instance; 2389 struct lock_class *class; 2390 2391 if (lock->lo_witness == NULL || witness_watch < 1 || KERNEL_PANICKED()) 2392 return; 2393 class = LOCK_CLASS(lock); 2394 if ((class->lc_flags & LC_SLEEPLOCK) != 0) 2395 instance = find_instance(curthread->td_sleeplocks, lock); 2396 else if ((class->lc_flags & LC_SPINLOCK) != 0) 2397 instance = find_instance(PCPU_GET(spinlocks), lock); 2398 else { 2399 kassert_panic("Lock (%s) %s is not sleep or spin!", 2400 class->lc_name, lock->lo_name); 2401 return; 2402 } 2403 switch (flags) { 2404 case LA_UNLOCKED: 2405 if (instance != NULL) 2406 kassert_panic("Lock (%s) %s locked @ %s:%d.", 2407 class->lc_name, lock->lo_name, 2408 fixup_filename(file), line); 2409 break; 2410 case LA_LOCKED: 2411 case LA_LOCKED | LA_RECURSED: 2412 case LA_LOCKED | LA_NOTRECURSED: 2413 case LA_SLOCKED: 2414 case LA_SLOCKED | LA_RECURSED: 2415 case LA_SLOCKED | LA_NOTRECURSED: 2416 case LA_XLOCKED: 2417 case LA_XLOCKED | LA_RECURSED: 2418 case LA_XLOCKED | LA_NOTRECURSED: 2419 if (instance == NULL) { 2420 kassert_panic("Lock (%s) %s not locked @ %s:%d.", 2421 class->lc_name, lock->lo_name, 2422 fixup_filename(file), line); 2423 break; 2424 } 2425 if ((flags & LA_XLOCKED) != 0 && 2426 (instance->li_flags & LI_EXCLUSIVE) == 0) 2427 kassert_panic( 2428 "Lock (%s) %s not exclusively locked @ %s:%d.", 2429 class->lc_name, lock->lo_name, 2430 fixup_filename(file), line); 2431 if ((flags & LA_SLOCKED) != 0 && 2432 (instance->li_flags & LI_EXCLUSIVE) != 0) 2433 kassert_panic( 2434 "Lock (%s) %s exclusively locked @ %s:%d.", 2435 class->lc_name, lock->lo_name, 2436 fixup_filename(file), line); 2437 if ((flags & LA_RECURSED) != 0 && 2438 (instance->li_flags & LI_RECURSEMASK) == 0) 2439 kassert_panic("Lock (%s) %s not recursed @ %s:%d.", 2440 class->lc_name, lock->lo_name, 2441 fixup_filename(file), line); 2442 if ((flags & LA_NOTRECURSED) != 0 && 2443 (instance->li_flags & LI_RECURSEMASK) != 0) 2444 kassert_panic("Lock (%s) %s recursed @ %s:%d.", 2445 class->lc_name, lock->lo_name, 2446 fixup_filename(file), line); 2447 break; 2448 default: 2449 kassert_panic("Invalid lock assertion at %s:%d.", 2450 fixup_filename(file), line); 2451 2452 } 2453 #endif /* INVARIANT_SUPPORT */ 2454 } 2455 2456 static void 2457 witness_setflag(struct lock_object *lock, int flag, int set) 2458 { 2459 struct lock_list_entry *lock_list; 2460 struct lock_instance *instance; 2461 struct lock_class *class; 2462 2463 if (lock->lo_witness == NULL || witness_watch == -1 || KERNEL_PANICKED()) 2464 return; 2465 class = LOCK_CLASS(lock); 2466 if (class->lc_flags & LC_SLEEPLOCK) 2467 lock_list = curthread->td_sleeplocks; 2468 else { 2469 if (witness_skipspin) 2470 return; 2471 lock_list = PCPU_GET(spinlocks); 2472 } 2473 instance = find_instance(lock_list, lock); 2474 if (instance == NULL) { 2475 kassert_panic("%s: lock (%s) %s not locked", __func__, 2476 class->lc_name, lock->lo_name); 2477 return; 2478 } 2479 2480 if (set) 2481 instance->li_flags |= flag; 2482 else 2483 instance->li_flags &= ~flag; 2484 } 2485 2486 void 2487 witness_norelease(struct lock_object *lock) 2488 { 2489 2490 witness_setflag(lock, LI_NORELEASE, 1); 2491 } 2492 2493 void 2494 witness_releaseok(struct lock_object *lock) 2495 { 2496 2497 witness_setflag(lock, LI_NORELEASE, 0); 2498 } 2499 2500 #ifdef DDB 2501 static void 2502 witness_ddb_list(struct thread *td) 2503 { 2504 2505 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); 2506 KASSERT(kdb_active, ("%s: not in the debugger", __func__)); 2507 2508 if (witness_watch < 1) 2509 return; 2510 2511 witness_list_locks(&td->td_sleeplocks, db_printf); 2512 2513 /* 2514 * We only handle spinlocks if td == curthread. This is somewhat broken 2515 * if td is currently executing on some other CPU and holds spin locks 2516 * as we won't display those locks. If we had a MI way of getting 2517 * the per-cpu data for a given cpu then we could use 2518 * td->td_oncpu to get the list of spinlocks for this thread 2519 * and "fix" this. 2520 * 2521 * That still wouldn't really fix this unless we locked the scheduler 2522 * lock or stopped the other CPU to make sure it wasn't changing the 2523 * list out from under us. It is probably best to just not try to 2524 * handle threads on other CPU's for now. 2525 */ 2526 if (td == curthread && PCPU_GET(spinlocks) != NULL) 2527 witness_list_locks(PCPU_PTR(spinlocks), db_printf); 2528 } 2529 2530 DB_SHOW_COMMAND(locks, db_witness_list) 2531 { 2532 struct thread *td; 2533 2534 if (have_addr) 2535 td = db_lookup_thread(addr, true); 2536 else 2537 td = kdb_thread; 2538 witness_ddb_list(td); 2539 } 2540 2541 DB_SHOW_ALL_COMMAND(locks, db_witness_list_all) 2542 { 2543 struct thread *td; 2544 struct proc *p; 2545 2546 /* 2547 * It would be nice to list only threads and processes that actually 2548 * held sleep locks, but that information is currently not exported 2549 * by WITNESS. 2550 */ 2551 FOREACH_PROC_IN_SYSTEM(p) { 2552 if (!witness_proc_has_locks(p)) 2553 continue; 2554 FOREACH_THREAD_IN_PROC(p, td) { 2555 if (!witness_thread_has_locks(td)) 2556 continue; 2557 db_printf("Process %d (%s) thread %p (%d)\n", p->p_pid, 2558 p->p_comm, td, td->td_tid); 2559 witness_ddb_list(td); 2560 if (db_pager_quit) 2561 return; 2562 } 2563 } 2564 } 2565 DB_SHOW_ALIAS(alllocks, db_witness_list_all) 2566 2567 DB_SHOW_COMMAND(witness, db_witness_display) 2568 { 2569 2570 witness_ddb_display(db_printf); 2571 } 2572 #endif 2573 2574 static void 2575 sbuf_print_witness_badstacks(struct sbuf *sb, size_t *oldidx) 2576 { 2577 struct witness_lock_order_data *data1, *data2, *tmp_data1, *tmp_data2; 2578 struct witness *tmp_w1, *tmp_w2, *w1, *w2; 2579 int generation, i, j; 2580 2581 tmp_data1 = NULL; 2582 tmp_data2 = NULL; 2583 tmp_w1 = NULL; 2584 tmp_w2 = NULL; 2585 2586 /* Allocate and init temporary storage space. */ 2587 tmp_w1 = malloc(sizeof(struct witness), M_TEMP, M_WAITOK | M_ZERO); 2588 tmp_w2 = malloc(sizeof(struct witness), M_TEMP, M_WAITOK | M_ZERO); 2589 tmp_data1 = malloc(sizeof(struct witness_lock_order_data), M_TEMP, 2590 M_WAITOK | M_ZERO); 2591 tmp_data2 = malloc(sizeof(struct witness_lock_order_data), M_TEMP, 2592 M_WAITOK | M_ZERO); 2593 stack_zero(&tmp_data1->wlod_stack); 2594 stack_zero(&tmp_data2->wlod_stack); 2595 2596 restart: 2597 mtx_lock_spin(&w_mtx); 2598 generation = w_generation; 2599 mtx_unlock_spin(&w_mtx); 2600 sbuf_printf(sb, "Number of known direct relationships is %d\n", 2601 w_lohash.wloh_count); 2602 for (i = 1; i < w_max_used_index; i++) { 2603 mtx_lock_spin(&w_mtx); 2604 if (generation != w_generation) { 2605 mtx_unlock_spin(&w_mtx); 2606 2607 /* The graph has changed, try again. */ 2608 *oldidx = 0; 2609 sbuf_clear(sb); 2610 goto restart; 2611 } 2612 2613 w1 = &w_data[i]; 2614 if (w1->w_reversed == 0) { 2615 mtx_unlock_spin(&w_mtx); 2616 continue; 2617 } 2618 2619 /* Copy w1 locally so we can release the spin lock. */ 2620 *tmp_w1 = *w1; 2621 mtx_unlock_spin(&w_mtx); 2622 2623 if (tmp_w1->w_reversed == 0) 2624 continue; 2625 for (j = 1; j < w_max_used_index; j++) { 2626 if ((w_rmatrix[i][j] & WITNESS_REVERSAL) == 0 || i > j) 2627 continue; 2628 2629 mtx_lock_spin(&w_mtx); 2630 if (generation != w_generation) { 2631 mtx_unlock_spin(&w_mtx); 2632 2633 /* The graph has changed, try again. */ 2634 *oldidx = 0; 2635 sbuf_clear(sb); 2636 goto restart; 2637 } 2638 2639 w2 = &w_data[j]; 2640 data1 = witness_lock_order_get(w1, w2); 2641 data2 = witness_lock_order_get(w2, w1); 2642 2643 /* 2644 * Copy information locally so we can release the 2645 * spin lock. 2646 */ 2647 *tmp_w2 = *w2; 2648 2649 if (data1) { 2650 stack_zero(&tmp_data1->wlod_stack); 2651 stack_copy(&data1->wlod_stack, 2652 &tmp_data1->wlod_stack); 2653 } 2654 if (data2 && data2 != data1) { 2655 stack_zero(&tmp_data2->wlod_stack); 2656 stack_copy(&data2->wlod_stack, 2657 &tmp_data2->wlod_stack); 2658 } 2659 mtx_unlock_spin(&w_mtx); 2660 2661 if (blessed(tmp_w1, tmp_w2)) 2662 continue; 2663 2664 sbuf_printf(sb, 2665 "\nLock order reversal between \"%s\"(%s) and \"%s\"(%s)!\n", 2666 tmp_w1->w_name, tmp_w1->w_class->lc_name, 2667 tmp_w2->w_name, tmp_w2->w_class->lc_name); 2668 if (data1) { 2669 sbuf_printf(sb, 2670 "Lock order \"%s\"(%s) -> \"%s\"(%s) first seen at:\n", 2671 tmp_w1->w_name, tmp_w1->w_class->lc_name, 2672 tmp_w2->w_name, tmp_w2->w_class->lc_name); 2673 stack_sbuf_print(sb, &tmp_data1->wlod_stack); 2674 sbuf_printf(sb, "\n"); 2675 } 2676 if (data2 && data2 != data1) { 2677 sbuf_printf(sb, 2678 "Lock order \"%s\"(%s) -> \"%s\"(%s) first seen at:\n", 2679 tmp_w2->w_name, tmp_w2->w_class->lc_name, 2680 tmp_w1->w_name, tmp_w1->w_class->lc_name); 2681 stack_sbuf_print(sb, &tmp_data2->wlod_stack); 2682 sbuf_printf(sb, "\n"); 2683 } 2684 } 2685 } 2686 mtx_lock_spin(&w_mtx); 2687 if (generation != w_generation) { 2688 mtx_unlock_spin(&w_mtx); 2689 2690 /* 2691 * The graph changed while we were printing stack data, 2692 * try again. 2693 */ 2694 *oldidx = 0; 2695 sbuf_clear(sb); 2696 goto restart; 2697 } 2698 mtx_unlock_spin(&w_mtx); 2699 2700 /* Free temporary storage space. */ 2701 free(tmp_data1, M_TEMP); 2702 free(tmp_data2, M_TEMP); 2703 free(tmp_w1, M_TEMP); 2704 free(tmp_w2, M_TEMP); 2705 } 2706 2707 static int 2708 sysctl_debug_witness_badstacks(SYSCTL_HANDLER_ARGS) 2709 { 2710 struct sbuf *sb; 2711 int error; 2712 2713 if (witness_watch < 1) { 2714 error = SYSCTL_OUT(req, w_notrunning, sizeof(w_notrunning)); 2715 return (error); 2716 } 2717 if (witness_cold) { 2718 error = SYSCTL_OUT(req, w_stillcold, sizeof(w_stillcold)); 2719 return (error); 2720 } 2721 error = 0; 2722 sb = sbuf_new(NULL, NULL, badstack_sbuf_size, SBUF_AUTOEXTEND); 2723 if (sb == NULL) 2724 return (ENOMEM); 2725 2726 sbuf_print_witness_badstacks(sb, &req->oldidx); 2727 2728 sbuf_finish(sb); 2729 error = SYSCTL_OUT(req, sbuf_data(sb), sbuf_len(sb) + 1); 2730 sbuf_delete(sb); 2731 2732 return (error); 2733 } 2734 2735 #ifdef DDB 2736 static int 2737 sbuf_db_printf_drain(void *arg __unused, const char *data, int len) 2738 { 2739 2740 return (db_printf("%.*s", len, data)); 2741 } 2742 2743 DB_SHOW_COMMAND(badstacks, db_witness_badstacks) 2744 { 2745 struct sbuf sb; 2746 char buffer[128]; 2747 size_t dummy; 2748 2749 sbuf_new(&sb, buffer, sizeof(buffer), SBUF_FIXEDLEN); 2750 sbuf_set_drain(&sb, sbuf_db_printf_drain, NULL); 2751 sbuf_print_witness_badstacks(&sb, &dummy); 2752 sbuf_finish(&sb); 2753 } 2754 #endif 2755 2756 static int 2757 sysctl_debug_witness_channel(SYSCTL_HANDLER_ARGS) 2758 { 2759 static const struct { 2760 enum witness_channel channel; 2761 const char *name; 2762 } channels[] = { 2763 { WITNESS_CONSOLE, "console" }, 2764 { WITNESS_LOG, "log" }, 2765 { WITNESS_NONE, "none" }, 2766 }; 2767 char buf[16]; 2768 u_int i; 2769 int error; 2770 2771 buf[0] = '\0'; 2772 for (i = 0; i < nitems(channels); i++) 2773 if (witness_channel == channels[i].channel) { 2774 snprintf(buf, sizeof(buf), "%s", channels[i].name); 2775 break; 2776 } 2777 2778 error = sysctl_handle_string(oidp, buf, sizeof(buf), req); 2779 if (error != 0 || req->newptr == NULL) 2780 return (error); 2781 2782 error = EINVAL; 2783 for (i = 0; i < nitems(channels); i++) 2784 if (strcmp(channels[i].name, buf) == 0) { 2785 witness_channel = channels[i].channel; 2786 error = 0; 2787 break; 2788 } 2789 return (error); 2790 } 2791 2792 static int 2793 sysctl_debug_witness_fullgraph(SYSCTL_HANDLER_ARGS) 2794 { 2795 struct witness *w; 2796 struct sbuf *sb; 2797 int error; 2798 2799 #ifdef __i386__ 2800 error = SYSCTL_OUT(req, w_notallowed, sizeof(w_notallowed)); 2801 return (error); 2802 #endif 2803 2804 if (witness_watch < 1) { 2805 error = SYSCTL_OUT(req, w_notrunning, sizeof(w_notrunning)); 2806 return (error); 2807 } 2808 if (witness_cold) { 2809 error = SYSCTL_OUT(req, w_stillcold, sizeof(w_stillcold)); 2810 return (error); 2811 } 2812 error = 0; 2813 2814 error = sysctl_wire_old_buffer(req, 0); 2815 if (error != 0) 2816 return (error); 2817 sb = sbuf_new_for_sysctl(NULL, NULL, FULLGRAPH_SBUF_SIZE, req); 2818 if (sb == NULL) 2819 return (ENOMEM); 2820 sbuf_printf(sb, "\n"); 2821 2822 mtx_lock_spin(&w_mtx); 2823 STAILQ_FOREACH(w, &w_all, w_list) 2824 w->w_displayed = 0; 2825 STAILQ_FOREACH(w, &w_all, w_list) 2826 witness_add_fullgraph(sb, w); 2827 mtx_unlock_spin(&w_mtx); 2828 2829 /* 2830 * Close the sbuf and return to userland. 2831 */ 2832 error = sbuf_finish(sb); 2833 sbuf_delete(sb); 2834 2835 return (error); 2836 } 2837 2838 static int 2839 sysctl_debug_witness_watch(SYSCTL_HANDLER_ARGS) 2840 { 2841 int error, value; 2842 2843 value = witness_watch; 2844 error = sysctl_handle_int(oidp, &value, 0, req); 2845 if (error != 0 || req->newptr == NULL) 2846 return (error); 2847 if (value > 1 || value < -1 || 2848 (witness_watch == -1 && value != witness_watch)) 2849 return (EINVAL); 2850 witness_watch = value; 2851 return (0); 2852 } 2853 2854 static void 2855 witness_add_fullgraph(struct sbuf *sb, struct witness *w) 2856 { 2857 int i; 2858 2859 if (w->w_displayed != 0 || (w->w_file == NULL && w->w_line == 0)) 2860 return; 2861 w->w_displayed = 1; 2862 2863 WITNESS_INDEX_ASSERT(w->w_index); 2864 for (i = 1; i <= w_max_used_index; i++) { 2865 if (w_rmatrix[w->w_index][i] & WITNESS_PARENT) { 2866 sbuf_printf(sb, "\"%s\",\"%s\"\n", w->w_name, 2867 w_data[i].w_name); 2868 witness_add_fullgraph(sb, &w_data[i]); 2869 } 2870 } 2871 } 2872 2873 /* 2874 * A simple hash function. Takes a key pointer and a key size. If size == 0, 2875 * interprets the key as a string and reads until the null 2876 * terminator. Otherwise, reads the first size bytes. Returns an unsigned 32-bit 2877 * hash value computed from the key. 2878 */ 2879 static uint32_t 2880 witness_hash_djb2(const uint8_t *key, uint32_t size) 2881 { 2882 unsigned int hash = 5381; 2883 int i; 2884 2885 /* hash = hash * 33 + key[i] */ 2886 if (size) 2887 for (i = 0; i < size; i++) 2888 hash = ((hash << 5) + hash) + (unsigned int)key[i]; 2889 else 2890 for (i = 0; key[i] != 0; i++) 2891 hash = ((hash << 5) + hash) + (unsigned int)key[i]; 2892 2893 return (hash); 2894 } 2895 2896 2897 /* 2898 * Initializes the two witness hash tables. Called exactly once from 2899 * witness_initialize(). 2900 */ 2901 static void 2902 witness_init_hash_tables(void) 2903 { 2904 int i; 2905 2906 MPASS(witness_cold); 2907 2908 /* Initialize the hash tables. */ 2909 for (i = 0; i < WITNESS_HASH_SIZE; i++) 2910 w_hash.wh_array[i] = NULL; 2911 2912 w_hash.wh_size = WITNESS_HASH_SIZE; 2913 w_hash.wh_count = 0; 2914 2915 /* Initialize the lock order data hash. */ 2916 w_lofree = NULL; 2917 for (i = 0; i < WITNESS_LO_DATA_COUNT; i++) { 2918 memset(&w_lodata[i], 0, sizeof(w_lodata[i])); 2919 w_lodata[i].wlod_next = w_lofree; 2920 w_lofree = &w_lodata[i]; 2921 } 2922 w_lohash.wloh_size = WITNESS_LO_HASH_SIZE; 2923 w_lohash.wloh_count = 0; 2924 for (i = 0; i < WITNESS_LO_HASH_SIZE; i++) 2925 w_lohash.wloh_array[i] = NULL; 2926 } 2927 2928 static struct witness * 2929 witness_hash_get(const char *key) 2930 { 2931 struct witness *w; 2932 uint32_t hash; 2933 2934 MPASS(key != NULL); 2935 if (witness_cold == 0) 2936 mtx_assert(&w_mtx, MA_OWNED); 2937 hash = witness_hash_djb2(key, 0) % w_hash.wh_size; 2938 w = w_hash.wh_array[hash]; 2939 while (w != NULL) { 2940 if (strcmp(w->w_name, key) == 0) 2941 goto out; 2942 w = w->w_hash_next; 2943 } 2944 2945 out: 2946 return (w); 2947 } 2948 2949 static void 2950 witness_hash_put(struct witness *w) 2951 { 2952 uint32_t hash; 2953 2954 MPASS(w != NULL); 2955 MPASS(w->w_name != NULL); 2956 if (witness_cold == 0) 2957 mtx_assert(&w_mtx, MA_OWNED); 2958 KASSERT(witness_hash_get(w->w_name) == NULL, 2959 ("%s: trying to add a hash entry that already exists!", __func__)); 2960 KASSERT(w->w_hash_next == NULL, 2961 ("%s: w->w_hash_next != NULL", __func__)); 2962 2963 hash = witness_hash_djb2(w->w_name, 0) % w_hash.wh_size; 2964 w->w_hash_next = w_hash.wh_array[hash]; 2965 w_hash.wh_array[hash] = w; 2966 w_hash.wh_count++; 2967 } 2968 2969 2970 static struct witness_lock_order_data * 2971 witness_lock_order_get(struct witness *parent, struct witness *child) 2972 { 2973 struct witness_lock_order_data *data = NULL; 2974 struct witness_lock_order_key key; 2975 unsigned int hash; 2976 2977 MPASS(parent != NULL && child != NULL); 2978 key.from = parent->w_index; 2979 key.to = child->w_index; 2980 WITNESS_INDEX_ASSERT(key.from); 2981 WITNESS_INDEX_ASSERT(key.to); 2982 if ((w_rmatrix[parent->w_index][child->w_index] 2983 & WITNESS_LOCK_ORDER_KNOWN) == 0) 2984 goto out; 2985 2986 hash = witness_hash_djb2((const char*)&key, 2987 sizeof(key)) % w_lohash.wloh_size; 2988 data = w_lohash.wloh_array[hash]; 2989 while (data != NULL) { 2990 if (witness_lock_order_key_equal(&data->wlod_key, &key)) 2991 break; 2992 data = data->wlod_next; 2993 } 2994 2995 out: 2996 return (data); 2997 } 2998 2999 /* 3000 * Verify that parent and child have a known relationship, are not the same, 3001 * and child is actually a child of parent. This is done without w_mtx 3002 * to avoid contention in the common case. 3003 */ 3004 static int 3005 witness_lock_order_check(struct witness *parent, struct witness *child) 3006 { 3007 3008 if (parent != child && 3009 w_rmatrix[parent->w_index][child->w_index] 3010 & WITNESS_LOCK_ORDER_KNOWN && 3011 isitmychild(parent, child)) 3012 return (1); 3013 3014 return (0); 3015 } 3016 3017 static int 3018 witness_lock_order_add(struct witness *parent, struct witness *child) 3019 { 3020 struct witness_lock_order_data *data = NULL; 3021 struct witness_lock_order_key key; 3022 unsigned int hash; 3023 3024 MPASS(parent != NULL && child != NULL); 3025 key.from = parent->w_index; 3026 key.to = child->w_index; 3027 WITNESS_INDEX_ASSERT(key.from); 3028 WITNESS_INDEX_ASSERT(key.to); 3029 if (w_rmatrix[parent->w_index][child->w_index] 3030 & WITNESS_LOCK_ORDER_KNOWN) 3031 return (1); 3032 3033 hash = witness_hash_djb2((const char*)&key, 3034 sizeof(key)) % w_lohash.wloh_size; 3035 w_rmatrix[parent->w_index][child->w_index] |= WITNESS_LOCK_ORDER_KNOWN; 3036 data = w_lofree; 3037 if (data == NULL) 3038 return (0); 3039 w_lofree = data->wlod_next; 3040 data->wlod_next = w_lohash.wloh_array[hash]; 3041 data->wlod_key = key; 3042 w_lohash.wloh_array[hash] = data; 3043 w_lohash.wloh_count++; 3044 stack_zero(&data->wlod_stack); 3045 stack_save(&data->wlod_stack); 3046 return (1); 3047 } 3048 3049 /* Call this whenever the structure of the witness graph changes. */ 3050 static void 3051 witness_increment_graph_generation(void) 3052 { 3053 3054 if (witness_cold == 0) 3055 mtx_assert(&w_mtx, MA_OWNED); 3056 w_generation++; 3057 } 3058 3059 static int 3060 witness_output_drain(void *arg __unused, const char *data, int len) 3061 { 3062 3063 witness_output("%.*s", len, data); 3064 return (len); 3065 } 3066 3067 static void 3068 witness_debugger(int cond, const char *msg) 3069 { 3070 char buf[32]; 3071 struct sbuf sb; 3072 struct stack st; 3073 3074 if (!cond) 3075 return; 3076 3077 if (witness_trace) { 3078 sbuf_new(&sb, buf, sizeof(buf), SBUF_FIXEDLEN); 3079 sbuf_set_drain(&sb, witness_output_drain, NULL); 3080 3081 stack_zero(&st); 3082 stack_save(&st); 3083 witness_output("stack backtrace:\n"); 3084 stack_sbuf_print_ddb(&sb, &st); 3085 3086 sbuf_finish(&sb); 3087 } 3088 3089 #ifdef KDB 3090 if (witness_kdb) 3091 kdb_enter(KDB_WHY_WITNESS, msg); 3092 #endif 3093 } 3094