1 /*- 2 * SPDX-License-Identifier: BSD-3-Clause 3 * 4 * Copyright (c) 2008 Isilon Systems, Inc. 5 * Copyright (c) 2008 Ilya Maykov <ivmaykov@gmail.com> 6 * Copyright (c) 1998 Berkeley Software Design, Inc. 7 * All rights reserved. 8 * 9 * Redistribution and use in source and binary forms, with or without 10 * modification, are permitted provided that the following conditions 11 * are met: 12 * 1. Redistributions of source code must retain the above copyright 13 * notice, this list of conditions and the following disclaimer. 14 * 2. Redistributions in binary form must reproduce the above copyright 15 * notice, this list of conditions and the following disclaimer in the 16 * documentation and/or other materials provided with the distribution. 17 * 3. Berkeley Software Design Inc's name may not be used to endorse or 18 * promote products derived from this software without specific prior 19 * written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY BERKELEY SOFTWARE DESIGN INC ``AS IS'' AND 22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24 * ARE DISCLAIMED. IN NO EVENT SHALL BERKELEY SOFTWARE DESIGN INC BE LIABLE 25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31 * SUCH DAMAGE. 32 * 33 * from BSDI $Id: mutex_witness.c,v 1.1.2.20 2000/04/27 03:10:27 cp Exp $ 34 * and BSDI $Id: synch_machdep.c,v 2.3.2.39 2000/04/27 03:10:25 cp Exp $ 35 */ 36 37 /* 38 * Implementation of the `witness' lock verifier. Originally implemented for 39 * mutexes in BSD/OS. Extended to handle generic lock objects and lock 40 * classes in FreeBSD. 41 */ 42 43 /* 44 * Main Entry: witness 45 * Pronunciation: 'wit-n&s 46 * Function: noun 47 * Etymology: Middle English witnesse, from Old English witnes knowledge, 48 * testimony, witness, from 2wit 49 * Date: before 12th century 50 * 1 : attestation of a fact or event : TESTIMONY 51 * 2 : one that gives evidence; specifically : one who testifies in 52 * a cause or before a judicial tribunal 53 * 3 : one asked to be present at a transaction so as to be able to 54 * testify to its having taken place 55 * 4 : one who has personal knowledge of something 56 * 5 a : something serving as evidence or proof : SIGN 57 * b : public affirmation by word or example of usually 58 * religious faith or conviction <the heroic witness to divine 59 * life -- Pilot> 60 * 6 capitalized : a member of the Jehovah's Witnesses 61 */ 62 63 /* 64 * Special rules concerning Giant and lock orders: 65 * 66 * 1) Giant must be acquired before any other mutexes. Stated another way, 67 * no other mutex may be held when Giant is acquired. 68 * 69 * 2) Giant must be released when blocking on a sleepable lock. 70 * 71 * This rule is less obvious, but is a result of Giant providing the same 72 * semantics as spl(). Basically, when a thread sleeps, it must release 73 * Giant. When a thread blocks on a sleepable lock, it sleeps. Hence rule 74 * 2). 75 * 76 * 3) Giant may be acquired before or after sleepable locks. 77 * 78 * This rule is also not quite as obvious. Giant may be acquired after 79 * a sleepable lock because it is a non-sleepable lock and non-sleepable 80 * locks may always be acquired while holding a sleepable lock. The second 81 * case, Giant before a sleepable lock, follows from rule 2) above. Suppose 82 * you have two threads T1 and T2 and a sleepable lock X. Suppose that T1 83 * acquires X and blocks on Giant. Then suppose that T2 acquires Giant and 84 * blocks on X. When T2 blocks on X, T2 will release Giant allowing T1 to 85 * execute. Thus, acquiring Giant both before and after a sleepable lock 86 * will not result in a lock order reversal. 87 */ 88 89 #include <sys/cdefs.h> 90 __FBSDID("$FreeBSD$"); 91 92 #include "opt_ddb.h" 93 #include "opt_hwpmc_hooks.h" 94 #include "opt_stack.h" 95 #include "opt_witness.h" 96 97 #include <sys/param.h> 98 #include <sys/bus.h> 99 #include <sys/kdb.h> 100 #include <sys/kernel.h> 101 #include <sys/ktr.h> 102 #include <sys/lock.h> 103 #include <sys/malloc.h> 104 #include <sys/mutex.h> 105 #include <sys/priv.h> 106 #include <sys/proc.h> 107 #include <sys/sbuf.h> 108 #include <sys/sched.h> 109 #include <sys/stack.h> 110 #include <sys/sysctl.h> 111 #include <sys/syslog.h> 112 #include <sys/systm.h> 113 114 #ifdef DDB 115 #include <ddb/ddb.h> 116 #endif 117 118 #include <machine/stdarg.h> 119 120 #if !defined(DDB) && !defined(STACK) 121 #error "DDB or STACK options are required for WITNESS" 122 #endif 123 124 /* Note that these traces do not work with KTR_ALQ. */ 125 #if 0 126 #define KTR_WITNESS KTR_SUBSYS 127 #else 128 #define KTR_WITNESS 0 129 #endif 130 131 #define LI_RECURSEMASK 0x0000ffff /* Recursion depth of lock instance. */ 132 #define LI_EXCLUSIVE 0x00010000 /* Exclusive lock instance. */ 133 #define LI_NORELEASE 0x00020000 /* Lock not allowed to be released. */ 134 #define LI_SLEEPABLE 0x00040000 /* Lock may be held while sleeping. */ 135 136 #ifndef WITNESS_COUNT 137 #define WITNESS_COUNT 1536 138 #endif 139 #define WITNESS_HASH_SIZE 251 /* Prime, gives load factor < 2 */ 140 #define WITNESS_PENDLIST (512 + (MAXCPU * 4)) 141 142 /* Allocate 256 KB of stack data space */ 143 #define WITNESS_LO_DATA_COUNT 2048 144 145 /* Prime, gives load factor of ~2 at full load */ 146 #define WITNESS_LO_HASH_SIZE 1021 147 148 /* 149 * XXX: This is somewhat bogus, as we assume here that at most 2048 threads 150 * will hold LOCK_NCHILDREN locks. We handle failure ok, and we should 151 * probably be safe for the most part, but it's still a SWAG. 152 */ 153 #define LOCK_NCHILDREN 5 154 #define LOCK_CHILDCOUNT 2048 155 156 #define MAX_W_NAME 64 157 158 #define FULLGRAPH_SBUF_SIZE 512 159 160 /* 161 * These flags go in the witness relationship matrix and describe the 162 * relationship between any two struct witness objects. 163 */ 164 #define WITNESS_UNRELATED 0x00 /* No lock order relation. */ 165 #define WITNESS_PARENT 0x01 /* Parent, aka direct ancestor. */ 166 #define WITNESS_ANCESTOR 0x02 /* Direct or indirect ancestor. */ 167 #define WITNESS_CHILD 0x04 /* Child, aka direct descendant. */ 168 #define WITNESS_DESCENDANT 0x08 /* Direct or indirect descendant. */ 169 #define WITNESS_ANCESTOR_MASK (WITNESS_PARENT | WITNESS_ANCESTOR) 170 #define WITNESS_DESCENDANT_MASK (WITNESS_CHILD | WITNESS_DESCENDANT) 171 #define WITNESS_RELATED_MASK \ 172 (WITNESS_ANCESTOR_MASK | WITNESS_DESCENDANT_MASK) 173 #define WITNESS_REVERSAL 0x10 /* A lock order reversal has been 174 * observed. */ 175 #define WITNESS_RESERVED1 0x20 /* Unused flag, reserved. */ 176 #define WITNESS_RESERVED2 0x40 /* Unused flag, reserved. */ 177 #define WITNESS_LOCK_ORDER_KNOWN 0x80 /* This lock order is known. */ 178 179 /* Descendant to ancestor flags */ 180 #define WITNESS_DTOA(x) (((x) & WITNESS_RELATED_MASK) >> 2) 181 182 /* Ancestor to descendant flags */ 183 #define WITNESS_ATOD(x) (((x) & WITNESS_RELATED_MASK) << 2) 184 185 #define WITNESS_INDEX_ASSERT(i) \ 186 MPASS((i) > 0 && (i) <= w_max_used_index && (i) < witness_count) 187 188 static MALLOC_DEFINE(M_WITNESS, "Witness", "Witness"); 189 190 /* 191 * Lock instances. A lock instance is the data associated with a lock while 192 * it is held by witness. For example, a lock instance will hold the 193 * recursion count of a lock. Lock instances are held in lists. Spin locks 194 * are held in a per-cpu list while sleep locks are held in per-thread list. 195 */ 196 struct lock_instance { 197 struct lock_object *li_lock; 198 const char *li_file; 199 int li_line; 200 u_int li_flags; 201 }; 202 203 /* 204 * A simple list type used to build the list of locks held by a thread 205 * or CPU. We can't simply embed the list in struct lock_object since a 206 * lock may be held by more than one thread if it is a shared lock. Locks 207 * are added to the head of the list, so we fill up each list entry from 208 * "the back" logically. To ease some of the arithmetic, we actually fill 209 * in each list entry the normal way (children[0] then children[1], etc.) but 210 * when we traverse the list we read children[count-1] as the first entry 211 * down to children[0] as the final entry. 212 */ 213 struct lock_list_entry { 214 struct lock_list_entry *ll_next; 215 struct lock_instance ll_children[LOCK_NCHILDREN]; 216 u_int ll_count; 217 }; 218 219 /* 220 * The main witness structure. One of these per named lock type in the system 221 * (for example, "vnode interlock"). 222 */ 223 struct witness { 224 char w_name[MAX_W_NAME]; 225 uint32_t w_index; /* Index in the relationship matrix */ 226 struct lock_class *w_class; 227 STAILQ_ENTRY(witness) w_list; /* List of all witnesses. */ 228 STAILQ_ENTRY(witness) w_typelist; /* Witnesses of a type. */ 229 struct witness *w_hash_next; /* Linked list in hash buckets. */ 230 const char *w_file; /* File where last acquired */ 231 uint32_t w_line; /* Line where last acquired */ 232 uint32_t w_refcount; 233 uint16_t w_num_ancestors; /* direct/indirect 234 * ancestor count */ 235 uint16_t w_num_descendants; /* direct/indirect 236 * descendant count */ 237 int16_t w_ddb_level; 238 unsigned w_displayed:1; 239 unsigned w_reversed:1; 240 }; 241 242 STAILQ_HEAD(witness_list, witness); 243 244 /* 245 * The witness hash table. Keys are witness names (const char *), elements are 246 * witness objects (struct witness *). 247 */ 248 struct witness_hash { 249 struct witness *wh_array[WITNESS_HASH_SIZE]; 250 uint32_t wh_size; 251 uint32_t wh_count; 252 }; 253 254 /* 255 * Key type for the lock order data hash table. 256 */ 257 struct witness_lock_order_key { 258 uint16_t from; 259 uint16_t to; 260 }; 261 262 struct witness_lock_order_data { 263 struct stack wlod_stack; 264 struct witness_lock_order_key wlod_key; 265 struct witness_lock_order_data *wlod_next; 266 }; 267 268 /* 269 * The witness lock order data hash table. Keys are witness index tuples 270 * (struct witness_lock_order_key), elements are lock order data objects 271 * (struct witness_lock_order_data). 272 */ 273 struct witness_lock_order_hash { 274 struct witness_lock_order_data *wloh_array[WITNESS_LO_HASH_SIZE]; 275 u_int wloh_size; 276 u_int wloh_count; 277 }; 278 279 struct witness_blessed { 280 const char *b_lock1; 281 const char *b_lock2; 282 }; 283 284 struct witness_pendhelp { 285 const char *wh_type; 286 struct lock_object *wh_lock; 287 }; 288 289 struct witness_order_list_entry { 290 const char *w_name; 291 struct lock_class *w_class; 292 }; 293 294 /* 295 * Returns 0 if one of the locks is a spin lock and the other is not. 296 * Returns 1 otherwise. 297 */ 298 static __inline int 299 witness_lock_type_equal(struct witness *w1, struct witness *w2) 300 { 301 302 return ((w1->w_class->lc_flags & (LC_SLEEPLOCK | LC_SPINLOCK)) == 303 (w2->w_class->lc_flags & (LC_SLEEPLOCK | LC_SPINLOCK))); 304 } 305 306 static __inline int 307 witness_lock_order_key_equal(const struct witness_lock_order_key *a, 308 const struct witness_lock_order_key *b) 309 { 310 311 return (a->from == b->from && a->to == b->to); 312 } 313 314 static int _isitmyx(struct witness *w1, struct witness *w2, int rmask, 315 const char *fname); 316 static void adopt(struct witness *parent, struct witness *child); 317 static int blessed(struct witness *, struct witness *); 318 static void depart(struct witness *w); 319 static struct witness *enroll(const char *description, 320 struct lock_class *lock_class); 321 static struct lock_instance *find_instance(struct lock_list_entry *list, 322 const struct lock_object *lock); 323 static int isitmychild(struct witness *parent, struct witness *child); 324 static int isitmydescendant(struct witness *parent, struct witness *child); 325 static void itismychild(struct witness *parent, struct witness *child); 326 static int sysctl_debug_witness_badstacks(SYSCTL_HANDLER_ARGS); 327 static int sysctl_debug_witness_watch(SYSCTL_HANDLER_ARGS); 328 static int sysctl_debug_witness_fullgraph(SYSCTL_HANDLER_ARGS); 329 static int sysctl_debug_witness_channel(SYSCTL_HANDLER_ARGS); 330 static void witness_add_fullgraph(struct sbuf *sb, struct witness *parent); 331 #ifdef DDB 332 static void witness_ddb_compute_levels(void); 333 static void witness_ddb_display(int(*)(const char *fmt, ...)); 334 static void witness_ddb_display_descendants(int(*)(const char *fmt, ...), 335 struct witness *, int indent); 336 static void witness_ddb_display_list(int(*prnt)(const char *fmt, ...), 337 struct witness_list *list); 338 static void witness_ddb_level_descendants(struct witness *parent, int l); 339 static void witness_ddb_list(struct thread *td); 340 #endif 341 static void witness_enter_debugger(const char *msg); 342 static void witness_debugger(int cond, const char *msg); 343 static void witness_free(struct witness *m); 344 static struct witness *witness_get(void); 345 static uint32_t witness_hash_djb2(const uint8_t *key, uint32_t size); 346 static struct witness *witness_hash_get(const char *key); 347 static void witness_hash_put(struct witness *w); 348 static void witness_init_hash_tables(void); 349 static void witness_increment_graph_generation(void); 350 static void witness_lock_list_free(struct lock_list_entry *lle); 351 static struct lock_list_entry *witness_lock_list_get(void); 352 static int witness_lock_order_add(struct witness *parent, 353 struct witness *child); 354 static int witness_lock_order_check(struct witness *parent, 355 struct witness *child); 356 static struct witness_lock_order_data *witness_lock_order_get( 357 struct witness *parent, 358 struct witness *child); 359 static void witness_list_lock(struct lock_instance *instance, 360 int (*prnt)(const char *fmt, ...)); 361 static int witness_output(const char *fmt, ...) __printflike(1, 2); 362 static int witness_output_drain(void *arg __unused, const char *data, 363 int len); 364 static int witness_voutput(const char *fmt, va_list ap) __printflike(1, 0); 365 static void witness_setflag(struct lock_object *lock, int flag, int set); 366 367 FEATURE(witness, "kernel has witness(9) support"); 368 369 static SYSCTL_NODE(_debug, OID_AUTO, witness, CTLFLAG_RW | CTLFLAG_MPSAFE, NULL, 370 "Witness Locking"); 371 372 /* 373 * If set to 0, lock order checking is disabled. If set to -1, 374 * witness is completely disabled. Otherwise witness performs full 375 * lock order checking for all locks. At runtime, lock order checking 376 * may be toggled. However, witness cannot be reenabled once it is 377 * completely disabled. 378 */ 379 static int witness_watch = 1; 380 SYSCTL_PROC(_debug_witness, OID_AUTO, watch, 381 CTLFLAG_RWTUN | CTLTYPE_INT | CTLFLAG_MPSAFE, NULL, 0, 382 sysctl_debug_witness_watch, "I", 383 "witness is watching lock operations"); 384 385 #ifdef KDB 386 /* 387 * When KDB is enabled and witness_kdb is 1, it will cause the system 388 * to drop into kdebug() when: 389 * - a lock hierarchy violation occurs 390 * - locks are held when going to sleep. 391 */ 392 #ifdef WITNESS_KDB 393 int witness_kdb = 1; 394 #else 395 int witness_kdb = 0; 396 #endif 397 SYSCTL_INT(_debug_witness, OID_AUTO, kdb, CTLFLAG_RWTUN, &witness_kdb, 0, ""); 398 #endif /* KDB */ 399 400 #if defined(DDB) || defined(KDB) 401 /* 402 * When DDB or KDB is enabled and witness_trace is 1, it will cause the system 403 * to print a stack trace: 404 * - a lock hierarchy violation occurs 405 * - locks are held when going to sleep. 406 */ 407 int witness_trace = 1; 408 SYSCTL_INT(_debug_witness, OID_AUTO, trace, CTLFLAG_RWTUN, &witness_trace, 0, ""); 409 #endif /* DDB || KDB */ 410 411 #ifdef WITNESS_SKIPSPIN 412 int witness_skipspin = 1; 413 #else 414 int witness_skipspin = 0; 415 #endif 416 SYSCTL_INT(_debug_witness, OID_AUTO, skipspin, CTLFLAG_RDTUN, &witness_skipspin, 0, ""); 417 418 int badstack_sbuf_size; 419 420 int witness_count = WITNESS_COUNT; 421 SYSCTL_INT(_debug_witness, OID_AUTO, witness_count, CTLFLAG_RDTUN, 422 &witness_count, 0, ""); 423 424 /* 425 * Output channel for witness messages. By default we print to the console. 426 */ 427 enum witness_channel { 428 WITNESS_CONSOLE, 429 WITNESS_LOG, 430 WITNESS_NONE, 431 }; 432 433 static enum witness_channel witness_channel = WITNESS_CONSOLE; 434 SYSCTL_PROC(_debug_witness, OID_AUTO, output_channel, 435 CTLTYPE_STRING | CTLFLAG_RWTUN | CTLFLAG_MPSAFE, NULL, 0, 436 sysctl_debug_witness_channel, "A", 437 "Output channel for warnings"); 438 439 /* 440 * Call this to print out the relations between locks. 441 */ 442 SYSCTL_PROC(_debug_witness, OID_AUTO, fullgraph, 443 CTLTYPE_STRING | CTLFLAG_RD | CTLFLAG_MPSAFE, NULL, 0, 444 sysctl_debug_witness_fullgraph, "A", 445 "Show locks relation graphs"); 446 447 /* 448 * Call this to print out the witness faulty stacks. 449 */ 450 SYSCTL_PROC(_debug_witness, OID_AUTO, badstacks, 451 CTLTYPE_STRING | CTLFLAG_RD | CTLFLAG_MPSAFE, NULL, 0, 452 sysctl_debug_witness_badstacks, "A", 453 "Show bad witness stacks"); 454 455 static struct mtx w_mtx; 456 457 /* w_list */ 458 static struct witness_list w_free = STAILQ_HEAD_INITIALIZER(w_free); 459 static struct witness_list w_all = STAILQ_HEAD_INITIALIZER(w_all); 460 461 /* w_typelist */ 462 static struct witness_list w_spin = STAILQ_HEAD_INITIALIZER(w_spin); 463 static struct witness_list w_sleep = STAILQ_HEAD_INITIALIZER(w_sleep); 464 465 /* lock list */ 466 static struct lock_list_entry *w_lock_list_free = NULL; 467 static struct witness_pendhelp pending_locks[WITNESS_PENDLIST]; 468 static u_int pending_cnt; 469 470 static int w_free_cnt, w_spin_cnt, w_sleep_cnt; 471 SYSCTL_INT(_debug_witness, OID_AUTO, free_cnt, CTLFLAG_RD, &w_free_cnt, 0, ""); 472 SYSCTL_INT(_debug_witness, OID_AUTO, spin_cnt, CTLFLAG_RD, &w_spin_cnt, 0, ""); 473 SYSCTL_INT(_debug_witness, OID_AUTO, sleep_cnt, CTLFLAG_RD, &w_sleep_cnt, 0, 474 ""); 475 476 static struct witness *w_data; 477 static uint8_t **w_rmatrix; 478 static struct lock_list_entry w_locklistdata[LOCK_CHILDCOUNT]; 479 static struct witness_hash w_hash; /* The witness hash table. */ 480 481 /* The lock order data hash */ 482 static struct witness_lock_order_data w_lodata[WITNESS_LO_DATA_COUNT]; 483 static struct witness_lock_order_data *w_lofree = NULL; 484 static struct witness_lock_order_hash w_lohash; 485 static int w_max_used_index = 0; 486 static unsigned int w_generation = 0; 487 static const char w_notrunning[] = "Witness not running\n"; 488 static const char w_stillcold[] = "Witness is still cold\n"; 489 #ifdef __i386__ 490 static const char w_notallowed[] = "The sysctl is disabled on the arch\n"; 491 #endif 492 493 static struct witness_order_list_entry order_lists[] = { 494 /* 495 * sx locks 496 */ 497 { "proctree", &lock_class_sx }, 498 { "allproc", &lock_class_sx }, 499 { "allprison", &lock_class_sx }, 500 { NULL, NULL }, 501 /* 502 * Various mutexes 503 */ 504 { "Giant", &lock_class_mtx_sleep }, 505 { "pipe mutex", &lock_class_mtx_sleep }, 506 { "sigio lock", &lock_class_mtx_sleep }, 507 { "process group", &lock_class_mtx_sleep }, 508 #ifdef HWPMC_HOOKS 509 { "pmc-sleep", &lock_class_mtx_sleep }, 510 #endif 511 { "process lock", &lock_class_mtx_sleep }, 512 { "session", &lock_class_mtx_sleep }, 513 { "uidinfo hash", &lock_class_rw }, 514 { "time lock", &lock_class_mtx_sleep }, 515 { NULL, NULL }, 516 /* 517 * umtx 518 */ 519 { "umtx lock", &lock_class_mtx_sleep }, 520 { NULL, NULL }, 521 /* 522 * Sockets 523 */ 524 { "accept", &lock_class_mtx_sleep }, 525 { "so_snd", &lock_class_mtx_sleep }, 526 { "so_rcv", &lock_class_mtx_sleep }, 527 { "sellck", &lock_class_mtx_sleep }, 528 { NULL, NULL }, 529 /* 530 * Routing 531 */ 532 { "so_rcv", &lock_class_mtx_sleep }, 533 { "radix node head", &lock_class_rm }, 534 { "rtentry", &lock_class_mtx_sleep }, 535 { "ifaddr", &lock_class_mtx_sleep }, 536 { NULL, NULL }, 537 /* 538 * IPv4 multicast: 539 * protocol locks before interface locks, after UDP locks. 540 */ 541 { "in_multi_sx", &lock_class_sx }, 542 { "udpinp", &lock_class_rw }, 543 { "in_multi_list_mtx", &lock_class_mtx_sleep }, 544 { "igmp_mtx", &lock_class_mtx_sleep }, 545 { "ifnet_rw", &lock_class_rw }, 546 { "if_addr_lock", &lock_class_mtx_sleep }, 547 { NULL, NULL }, 548 /* 549 * IPv6 multicast: 550 * protocol locks before interface locks, after UDP locks. 551 */ 552 { "in6_multi_sx", &lock_class_sx }, 553 { "udpinp", &lock_class_rw }, 554 { "in6_multi_list_mtx", &lock_class_mtx_sleep }, 555 { "mld_mtx", &lock_class_mtx_sleep }, 556 { "ifnet_rw", &lock_class_rw }, 557 { "if_addr_lock", &lock_class_mtx_sleep }, 558 { NULL, NULL }, 559 /* 560 * UNIX Domain Sockets 561 */ 562 { "unp_link_rwlock", &lock_class_rw }, 563 { "unp_list_lock", &lock_class_mtx_sleep }, 564 { "unp", &lock_class_mtx_sleep }, 565 { "so_snd", &lock_class_mtx_sleep }, 566 { NULL, NULL }, 567 /* 568 * UDP/IP 569 */ 570 { "udp", &lock_class_mtx_sleep }, 571 { "udpinp", &lock_class_rw }, 572 { "so_snd", &lock_class_mtx_sleep }, 573 { NULL, NULL }, 574 /* 575 * TCP/IP 576 */ 577 { "tcp", &lock_class_mtx_sleep }, 578 { "tcpinp", &lock_class_rw }, 579 { "so_snd", &lock_class_mtx_sleep }, 580 { NULL, NULL }, 581 /* 582 * BPF 583 */ 584 { "bpf global lock", &lock_class_sx }, 585 { "bpf cdev lock", &lock_class_mtx_sleep }, 586 { NULL, NULL }, 587 /* 588 * NFS server 589 */ 590 { "nfsd_mtx", &lock_class_mtx_sleep }, 591 { "so_snd", &lock_class_mtx_sleep }, 592 { NULL, NULL }, 593 594 /* 595 * IEEE 802.11 596 */ 597 { "802.11 com lock", &lock_class_mtx_sleep}, 598 { NULL, NULL }, 599 /* 600 * Network drivers 601 */ 602 { "network driver", &lock_class_mtx_sleep}, 603 { NULL, NULL }, 604 605 /* 606 * Netgraph 607 */ 608 { "ng_node", &lock_class_mtx_sleep }, 609 { "ng_worklist", &lock_class_mtx_sleep }, 610 { NULL, NULL }, 611 /* 612 * CDEV 613 */ 614 { "vm map (system)", &lock_class_mtx_sleep }, 615 { "vnode interlock", &lock_class_mtx_sleep }, 616 { "cdev", &lock_class_mtx_sleep }, 617 { "devthrd", &lock_class_mtx_sleep }, 618 { NULL, NULL }, 619 /* 620 * VM 621 */ 622 { "vm map (user)", &lock_class_sx }, 623 { "vm object", &lock_class_rw }, 624 { "vm page", &lock_class_mtx_sleep }, 625 { "pmap pv global", &lock_class_rw }, 626 { "pmap", &lock_class_mtx_sleep }, 627 { "pmap pv list", &lock_class_rw }, 628 { "vm page free queue", &lock_class_mtx_sleep }, 629 { "vm pagequeue", &lock_class_mtx_sleep }, 630 { NULL, NULL }, 631 /* 632 * kqueue/VFS interaction 633 */ 634 { "kqueue", &lock_class_mtx_sleep }, 635 { "struct mount mtx", &lock_class_mtx_sleep }, 636 { "vnode interlock", &lock_class_mtx_sleep }, 637 { NULL, NULL }, 638 /* 639 * VFS namecache 640 */ 641 { "ncvn", &lock_class_mtx_sleep }, 642 { "ncbuc", &lock_class_rw }, 643 { "vnode interlock", &lock_class_mtx_sleep }, 644 { "ncneg", &lock_class_mtx_sleep }, 645 { NULL, NULL }, 646 /* 647 * ZFS locking 648 */ 649 { "dn->dn_mtx", &lock_class_sx }, 650 { "dr->dt.di.dr_mtx", &lock_class_sx }, 651 { "db->db_mtx", &lock_class_sx }, 652 { NULL, NULL }, 653 /* 654 * TCP log locks 655 */ 656 { "TCP ID tree", &lock_class_rw }, 657 { "tcp log id bucket", &lock_class_mtx_sleep }, 658 { "tcpinp", &lock_class_rw }, 659 { "TCP log expireq", &lock_class_mtx_sleep }, 660 { NULL, NULL }, 661 /* 662 * spin locks 663 */ 664 #ifdef SMP 665 { "ap boot", &lock_class_mtx_spin }, 666 #endif 667 { "rm.mutex_mtx", &lock_class_mtx_spin }, 668 { "sio", &lock_class_mtx_spin }, 669 #ifdef __i386__ 670 { "cy", &lock_class_mtx_spin }, 671 #endif 672 { "scc_hwmtx", &lock_class_mtx_spin }, 673 { "uart_hwmtx", &lock_class_mtx_spin }, 674 { "fast_taskqueue", &lock_class_mtx_spin }, 675 { "intr table", &lock_class_mtx_spin }, 676 { "process slock", &lock_class_mtx_spin }, 677 { "syscons video lock", &lock_class_mtx_spin }, 678 { "sleepq chain", &lock_class_mtx_spin }, 679 { "rm_spinlock", &lock_class_mtx_spin }, 680 { "turnstile chain", &lock_class_mtx_spin }, 681 { "turnstile lock", &lock_class_mtx_spin }, 682 { "sched lock", &lock_class_mtx_spin }, 683 { "td_contested", &lock_class_mtx_spin }, 684 { "callout", &lock_class_mtx_spin }, 685 { "entropy harvest mutex", &lock_class_mtx_spin }, 686 #ifdef SMP 687 { "smp rendezvous", &lock_class_mtx_spin }, 688 #endif 689 #ifdef __powerpc__ 690 { "tlb0", &lock_class_mtx_spin }, 691 #endif 692 { NULL, NULL }, 693 { "sched lock", &lock_class_mtx_spin }, 694 #ifdef HWPMC_HOOKS 695 { "pmc-per-proc", &lock_class_mtx_spin }, 696 #endif 697 { NULL, NULL }, 698 /* 699 * leaf locks 700 */ 701 { "intrcnt", &lock_class_mtx_spin }, 702 { "icu", &lock_class_mtx_spin }, 703 #ifdef __i386__ 704 { "allpmaps", &lock_class_mtx_spin }, 705 { "descriptor tables", &lock_class_mtx_spin }, 706 #endif 707 { "clk", &lock_class_mtx_spin }, 708 { "cpuset", &lock_class_mtx_spin }, 709 { "mprof lock", &lock_class_mtx_spin }, 710 { "zombie lock", &lock_class_mtx_spin }, 711 { "ALD Queue", &lock_class_mtx_spin }, 712 #if defined(__i386__) || defined(__amd64__) 713 { "pcicfg", &lock_class_mtx_spin }, 714 { "NDIS thread lock", &lock_class_mtx_spin }, 715 #endif 716 { "tw_osl_io_lock", &lock_class_mtx_spin }, 717 { "tw_osl_q_lock", &lock_class_mtx_spin }, 718 { "tw_cl_io_lock", &lock_class_mtx_spin }, 719 { "tw_cl_intr_lock", &lock_class_mtx_spin }, 720 { "tw_cl_gen_lock", &lock_class_mtx_spin }, 721 #ifdef HWPMC_HOOKS 722 { "pmc-leaf", &lock_class_mtx_spin }, 723 #endif 724 { "blocked lock", &lock_class_mtx_spin }, 725 { NULL, NULL }, 726 { NULL, NULL } 727 }; 728 729 /* 730 * Pairs of locks which have been blessed. Witness does not complain about 731 * order problems with blessed lock pairs. Please do not add an entry to the 732 * table without an explanatory comment. 733 */ 734 static struct witness_blessed blessed_list[] = { 735 /* 736 * See the comment in ufs_dirhash.c. Basically, a vnode lock serializes 737 * both lock orders, so a deadlock cannot happen as a result of this 738 * LOR. 739 */ 740 { "dirhash", "bufwait" }, 741 742 /* 743 * A UFS vnode may be locked in vget() while a buffer belonging to the 744 * parent directory vnode is locked. 745 */ 746 { "ufs", "bufwait" }, 747 }; 748 749 /* 750 * This global is set to 0 once it becomes safe to use the witness code. 751 */ 752 static int witness_cold = 1; 753 754 /* 755 * This global is set to 1 once the static lock orders have been enrolled 756 * so that a warning can be issued for any spin locks enrolled later. 757 */ 758 static int witness_spin_warn = 0; 759 760 /* Trim useless garbage from filenames. */ 761 static const char * 762 fixup_filename(const char *file) 763 { 764 765 if (file == NULL) 766 return (NULL); 767 while (strncmp(file, "../", 3) == 0) 768 file += 3; 769 return (file); 770 } 771 772 /* 773 * Calculate the size of early witness structures. 774 */ 775 int 776 witness_startup_count(void) 777 { 778 int sz; 779 780 sz = sizeof(struct witness) * witness_count; 781 sz += sizeof(*w_rmatrix) * (witness_count + 1); 782 sz += sizeof(*w_rmatrix[0]) * (witness_count + 1) * 783 (witness_count + 1); 784 785 return (sz); 786 } 787 788 /* 789 * The WITNESS-enabled diagnostic code. Note that the witness code does 790 * assume that the early boot is single-threaded at least until after this 791 * routine is completed. 792 */ 793 void 794 witness_startup(void *mem) 795 { 796 struct lock_object *lock; 797 struct witness_order_list_entry *order; 798 struct witness *w, *w1; 799 uintptr_t p; 800 int i; 801 802 p = (uintptr_t)mem; 803 w_data = (void *)p; 804 p += sizeof(struct witness) * witness_count; 805 806 w_rmatrix = (void *)p; 807 p += sizeof(*w_rmatrix) * (witness_count + 1); 808 809 for (i = 0; i < witness_count + 1; i++) { 810 w_rmatrix[i] = (void *)p; 811 p += sizeof(*w_rmatrix[i]) * (witness_count + 1); 812 } 813 badstack_sbuf_size = witness_count * 256; 814 815 /* 816 * We have to release Giant before initializing its witness 817 * structure so that WITNESS doesn't get confused. 818 */ 819 mtx_unlock(&Giant); 820 mtx_assert(&Giant, MA_NOTOWNED); 821 822 CTR1(KTR_WITNESS, "%s: initializing witness", __func__); 823 mtx_init(&w_mtx, "witness lock", NULL, MTX_SPIN | MTX_QUIET | 824 MTX_NOWITNESS | MTX_NOPROFILE); 825 for (i = witness_count - 1; i >= 0; i--) { 826 w = &w_data[i]; 827 memset(w, 0, sizeof(*w)); 828 w_data[i].w_index = i; /* Witness index never changes. */ 829 witness_free(w); 830 } 831 KASSERT(STAILQ_FIRST(&w_free)->w_index == 0, 832 ("%s: Invalid list of free witness objects", __func__)); 833 834 /* Witness with index 0 is not used to aid in debugging. */ 835 STAILQ_REMOVE_HEAD(&w_free, w_list); 836 w_free_cnt--; 837 838 for (i = 0; i < witness_count; i++) { 839 memset(w_rmatrix[i], 0, sizeof(*w_rmatrix[i]) * 840 (witness_count + 1)); 841 } 842 843 for (i = 0; i < LOCK_CHILDCOUNT; i++) 844 witness_lock_list_free(&w_locklistdata[i]); 845 witness_init_hash_tables(); 846 847 /* First add in all the specified order lists. */ 848 for (order = order_lists; order->w_name != NULL; order++) { 849 w = enroll(order->w_name, order->w_class); 850 if (w == NULL) 851 continue; 852 w->w_file = "order list"; 853 for (order++; order->w_name != NULL; order++) { 854 w1 = enroll(order->w_name, order->w_class); 855 if (w1 == NULL) 856 continue; 857 w1->w_file = "order list"; 858 itismychild(w, w1); 859 w = w1; 860 } 861 } 862 witness_spin_warn = 1; 863 864 /* Iterate through all locks and add them to witness. */ 865 for (i = 0; pending_locks[i].wh_lock != NULL; i++) { 866 lock = pending_locks[i].wh_lock; 867 KASSERT(lock->lo_flags & LO_WITNESS, 868 ("%s: lock %s is on pending list but not LO_WITNESS", 869 __func__, lock->lo_name)); 870 lock->lo_witness = enroll(pending_locks[i].wh_type, 871 LOCK_CLASS(lock)); 872 } 873 874 /* Mark the witness code as being ready for use. */ 875 witness_cold = 0; 876 877 mtx_lock(&Giant); 878 } 879 880 void 881 witness_init(struct lock_object *lock, const char *type) 882 { 883 struct lock_class *class; 884 885 /* Various sanity checks. */ 886 class = LOCK_CLASS(lock); 887 if ((lock->lo_flags & LO_RECURSABLE) != 0 && 888 (class->lc_flags & LC_RECURSABLE) == 0) 889 kassert_panic("%s: lock (%s) %s can not be recursable", 890 __func__, class->lc_name, lock->lo_name); 891 if ((lock->lo_flags & LO_SLEEPABLE) != 0 && 892 (class->lc_flags & LC_SLEEPABLE) == 0) 893 kassert_panic("%s: lock (%s) %s can not be sleepable", 894 __func__, class->lc_name, lock->lo_name); 895 if ((lock->lo_flags & LO_UPGRADABLE) != 0 && 896 (class->lc_flags & LC_UPGRADABLE) == 0) 897 kassert_panic("%s: lock (%s) %s can not be upgradable", 898 __func__, class->lc_name, lock->lo_name); 899 900 /* 901 * If we shouldn't watch this lock, then just clear lo_witness. 902 * Otherwise, if witness_cold is set, then it is too early to 903 * enroll this lock, so defer it to witness_initialize() by adding 904 * it to the pending_locks list. If it is not too early, then enroll 905 * the lock now. 906 */ 907 if (witness_watch < 1 || KERNEL_PANICKED() || 908 (lock->lo_flags & LO_WITNESS) == 0) 909 lock->lo_witness = NULL; 910 else if (witness_cold) { 911 pending_locks[pending_cnt].wh_lock = lock; 912 pending_locks[pending_cnt++].wh_type = type; 913 if (pending_cnt > WITNESS_PENDLIST) 914 panic("%s: pending locks list is too small, " 915 "increase WITNESS_PENDLIST\n", 916 __func__); 917 } else 918 lock->lo_witness = enroll(type, class); 919 } 920 921 void 922 witness_destroy(struct lock_object *lock) 923 { 924 struct lock_class *class; 925 struct witness *w; 926 927 class = LOCK_CLASS(lock); 928 929 if (witness_cold) 930 panic("lock (%s) %s destroyed while witness_cold", 931 class->lc_name, lock->lo_name); 932 933 /* XXX: need to verify that no one holds the lock */ 934 if ((lock->lo_flags & LO_WITNESS) == 0 || lock->lo_witness == NULL) 935 return; 936 w = lock->lo_witness; 937 938 mtx_lock_spin(&w_mtx); 939 MPASS(w->w_refcount > 0); 940 w->w_refcount--; 941 942 if (w->w_refcount == 0) 943 depart(w); 944 mtx_unlock_spin(&w_mtx); 945 } 946 947 #ifdef DDB 948 static void 949 witness_ddb_compute_levels(void) 950 { 951 struct witness *w; 952 953 /* 954 * First clear all levels. 955 */ 956 STAILQ_FOREACH(w, &w_all, w_list) 957 w->w_ddb_level = -1; 958 959 /* 960 * Look for locks with no parents and level all their descendants. 961 */ 962 STAILQ_FOREACH(w, &w_all, w_list) { 963 964 /* If the witness has ancestors (is not a root), skip it. */ 965 if (w->w_num_ancestors > 0) 966 continue; 967 witness_ddb_level_descendants(w, 0); 968 } 969 } 970 971 static void 972 witness_ddb_level_descendants(struct witness *w, int l) 973 { 974 int i; 975 976 if (w->w_ddb_level >= l) 977 return; 978 979 w->w_ddb_level = l; 980 l++; 981 982 for (i = 1; i <= w_max_used_index; i++) { 983 if (w_rmatrix[w->w_index][i] & WITNESS_PARENT) 984 witness_ddb_level_descendants(&w_data[i], l); 985 } 986 } 987 988 static void 989 witness_ddb_display_descendants(int(*prnt)(const char *fmt, ...), 990 struct witness *w, int indent) 991 { 992 int i; 993 994 for (i = 0; i < indent; i++) 995 prnt(" "); 996 prnt("%s (type: %s, depth: %d, active refs: %d)", 997 w->w_name, w->w_class->lc_name, 998 w->w_ddb_level, w->w_refcount); 999 if (w->w_displayed) { 1000 prnt(" -- (already displayed)\n"); 1001 return; 1002 } 1003 w->w_displayed = 1; 1004 if (w->w_file != NULL && w->w_line != 0) 1005 prnt(" -- last acquired @ %s:%d\n", fixup_filename(w->w_file), 1006 w->w_line); 1007 else 1008 prnt(" -- never acquired\n"); 1009 indent++; 1010 WITNESS_INDEX_ASSERT(w->w_index); 1011 for (i = 1; i <= w_max_used_index; i++) { 1012 if (db_pager_quit) 1013 return; 1014 if (w_rmatrix[w->w_index][i] & WITNESS_PARENT) 1015 witness_ddb_display_descendants(prnt, &w_data[i], 1016 indent); 1017 } 1018 } 1019 1020 static void 1021 witness_ddb_display_list(int(*prnt)(const char *fmt, ...), 1022 struct witness_list *list) 1023 { 1024 struct witness *w; 1025 1026 STAILQ_FOREACH(w, list, w_typelist) { 1027 if (w->w_file == NULL || w->w_ddb_level > 0) 1028 continue; 1029 1030 /* This lock has no anscestors - display its descendants. */ 1031 witness_ddb_display_descendants(prnt, w, 0); 1032 if (db_pager_quit) 1033 return; 1034 } 1035 } 1036 1037 static void 1038 witness_ddb_display(int(*prnt)(const char *fmt, ...)) 1039 { 1040 struct witness *w; 1041 1042 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); 1043 witness_ddb_compute_levels(); 1044 1045 /* Clear all the displayed flags. */ 1046 STAILQ_FOREACH(w, &w_all, w_list) 1047 w->w_displayed = 0; 1048 1049 /* 1050 * First, handle sleep locks which have been acquired at least 1051 * once. 1052 */ 1053 prnt("Sleep locks:\n"); 1054 witness_ddb_display_list(prnt, &w_sleep); 1055 if (db_pager_quit) 1056 return; 1057 1058 /* 1059 * Now do spin locks which have been acquired at least once. 1060 */ 1061 prnt("\nSpin locks:\n"); 1062 witness_ddb_display_list(prnt, &w_spin); 1063 if (db_pager_quit) 1064 return; 1065 1066 /* 1067 * Finally, any locks which have not been acquired yet. 1068 */ 1069 prnt("\nLocks which were never acquired:\n"); 1070 STAILQ_FOREACH(w, &w_all, w_list) { 1071 if (w->w_file != NULL || w->w_refcount == 0) 1072 continue; 1073 prnt("%s (type: %s, depth: %d)\n", w->w_name, 1074 w->w_class->lc_name, w->w_ddb_level); 1075 if (db_pager_quit) 1076 return; 1077 } 1078 } 1079 #endif /* DDB */ 1080 1081 int 1082 witness_defineorder(struct lock_object *lock1, struct lock_object *lock2) 1083 { 1084 1085 if (witness_watch == -1 || KERNEL_PANICKED()) 1086 return (0); 1087 1088 /* Require locks that witness knows about. */ 1089 if (lock1 == NULL || lock1->lo_witness == NULL || lock2 == NULL || 1090 lock2->lo_witness == NULL) 1091 return (EINVAL); 1092 1093 mtx_assert(&w_mtx, MA_NOTOWNED); 1094 mtx_lock_spin(&w_mtx); 1095 1096 /* 1097 * If we already have either an explicit or implied lock order that 1098 * is the other way around, then return an error. 1099 */ 1100 if (witness_watch && 1101 isitmydescendant(lock2->lo_witness, lock1->lo_witness)) { 1102 mtx_unlock_spin(&w_mtx); 1103 return (EDOOFUS); 1104 } 1105 1106 /* Try to add the new order. */ 1107 CTR3(KTR_WITNESS, "%s: adding %s as a child of %s", __func__, 1108 lock2->lo_witness->w_name, lock1->lo_witness->w_name); 1109 itismychild(lock1->lo_witness, lock2->lo_witness); 1110 mtx_unlock_spin(&w_mtx); 1111 return (0); 1112 } 1113 1114 void 1115 witness_checkorder(struct lock_object *lock, int flags, const char *file, 1116 int line, struct lock_object *interlock) 1117 { 1118 struct lock_list_entry *lock_list, *lle; 1119 struct lock_instance *lock1, *lock2, *plock; 1120 struct lock_class *class, *iclass; 1121 struct witness *w, *w1; 1122 struct thread *td; 1123 int i, j; 1124 1125 if (witness_cold || witness_watch < 1 || lock->lo_witness == NULL || 1126 KERNEL_PANICKED()) 1127 return; 1128 1129 w = lock->lo_witness; 1130 class = LOCK_CLASS(lock); 1131 td = curthread; 1132 1133 if (class->lc_flags & LC_SLEEPLOCK) { 1134 1135 /* 1136 * Since spin locks include a critical section, this check 1137 * implicitly enforces a lock order of all sleep locks before 1138 * all spin locks. 1139 */ 1140 if (td->td_critnest != 0 && !kdb_active) 1141 kassert_panic("acquiring blockable sleep lock with " 1142 "spinlock or critical section held (%s) %s @ %s:%d", 1143 class->lc_name, lock->lo_name, 1144 fixup_filename(file), line); 1145 1146 /* 1147 * If this is the first lock acquired then just return as 1148 * no order checking is needed. 1149 */ 1150 lock_list = td->td_sleeplocks; 1151 if (lock_list == NULL || lock_list->ll_count == 0) 1152 return; 1153 } else { 1154 1155 /* 1156 * If this is the first lock, just return as no order 1157 * checking is needed. Avoid problems with thread 1158 * migration pinning the thread while checking if 1159 * spinlocks are held. If at least one spinlock is held 1160 * the thread is in a safe path and it is allowed to 1161 * unpin it. 1162 */ 1163 sched_pin(); 1164 lock_list = PCPU_GET(spinlocks); 1165 if (lock_list == NULL || lock_list->ll_count == 0) { 1166 sched_unpin(); 1167 return; 1168 } 1169 sched_unpin(); 1170 } 1171 1172 /* 1173 * Check to see if we are recursing on a lock we already own. If 1174 * so, make sure that we don't mismatch exclusive and shared lock 1175 * acquires. 1176 */ 1177 lock1 = find_instance(lock_list, lock); 1178 if (lock1 != NULL) { 1179 if ((lock1->li_flags & LI_EXCLUSIVE) != 0 && 1180 (flags & LOP_EXCLUSIVE) == 0) { 1181 witness_output("shared lock of (%s) %s @ %s:%d\n", 1182 class->lc_name, lock->lo_name, 1183 fixup_filename(file), line); 1184 witness_output("while exclusively locked from %s:%d\n", 1185 fixup_filename(lock1->li_file), lock1->li_line); 1186 kassert_panic("excl->share"); 1187 } 1188 if ((lock1->li_flags & LI_EXCLUSIVE) == 0 && 1189 (flags & LOP_EXCLUSIVE) != 0) { 1190 witness_output("exclusive lock of (%s) %s @ %s:%d\n", 1191 class->lc_name, lock->lo_name, 1192 fixup_filename(file), line); 1193 witness_output("while share locked from %s:%d\n", 1194 fixup_filename(lock1->li_file), lock1->li_line); 1195 kassert_panic("share->excl"); 1196 } 1197 return; 1198 } 1199 1200 /* Warn if the interlock is not locked exactly once. */ 1201 if (interlock != NULL) { 1202 iclass = LOCK_CLASS(interlock); 1203 lock1 = find_instance(lock_list, interlock); 1204 if (lock1 == NULL) 1205 kassert_panic("interlock (%s) %s not locked @ %s:%d", 1206 iclass->lc_name, interlock->lo_name, 1207 fixup_filename(file), line); 1208 else if ((lock1->li_flags & LI_RECURSEMASK) != 0) 1209 kassert_panic("interlock (%s) %s recursed @ %s:%d", 1210 iclass->lc_name, interlock->lo_name, 1211 fixup_filename(file), line); 1212 } 1213 1214 /* 1215 * Find the previously acquired lock, but ignore interlocks. 1216 */ 1217 plock = &lock_list->ll_children[lock_list->ll_count - 1]; 1218 if (interlock != NULL && plock->li_lock == interlock) { 1219 if (lock_list->ll_count > 1) 1220 plock = 1221 &lock_list->ll_children[lock_list->ll_count - 2]; 1222 else { 1223 lle = lock_list->ll_next; 1224 1225 /* 1226 * The interlock is the only lock we hold, so 1227 * simply return. 1228 */ 1229 if (lle == NULL) 1230 return; 1231 plock = &lle->ll_children[lle->ll_count - 1]; 1232 } 1233 } 1234 1235 /* 1236 * Try to perform most checks without a lock. If this succeeds we 1237 * can skip acquiring the lock and return success. Otherwise we redo 1238 * the check with the lock held to handle races with concurrent updates. 1239 */ 1240 w1 = plock->li_lock->lo_witness; 1241 if (witness_lock_order_check(w1, w)) 1242 return; 1243 1244 mtx_lock_spin(&w_mtx); 1245 if (witness_lock_order_check(w1, w)) { 1246 mtx_unlock_spin(&w_mtx); 1247 return; 1248 } 1249 witness_lock_order_add(w1, w); 1250 1251 /* 1252 * Check for duplicate locks of the same type. Note that we only 1253 * have to check for this on the last lock we just acquired. Any 1254 * other cases will be caught as lock order violations. 1255 */ 1256 if (w1 == w) { 1257 i = w->w_index; 1258 if (!(lock->lo_flags & LO_DUPOK) && !(flags & LOP_DUPOK) && 1259 !(w_rmatrix[i][i] & WITNESS_REVERSAL)) { 1260 w_rmatrix[i][i] |= WITNESS_REVERSAL; 1261 w->w_reversed = 1; 1262 mtx_unlock_spin(&w_mtx); 1263 witness_output( 1264 "acquiring duplicate lock of same type: \"%s\"\n", 1265 w->w_name); 1266 witness_output(" 1st %s @ %s:%d\n", plock->li_lock->lo_name, 1267 fixup_filename(plock->li_file), plock->li_line); 1268 witness_output(" 2nd %s @ %s:%d\n", lock->lo_name, 1269 fixup_filename(file), line); 1270 witness_debugger(1, __func__); 1271 } else 1272 mtx_unlock_spin(&w_mtx); 1273 return; 1274 } 1275 mtx_assert(&w_mtx, MA_OWNED); 1276 1277 /* 1278 * If we know that the lock we are acquiring comes after 1279 * the lock we most recently acquired in the lock order tree, 1280 * then there is no need for any further checks. 1281 */ 1282 if (isitmychild(w1, w)) 1283 goto out; 1284 1285 for (j = 0, lle = lock_list; lle != NULL; lle = lle->ll_next) { 1286 for (i = lle->ll_count - 1; i >= 0; i--, j++) { 1287 struct stack pstack; 1288 bool pstackv, trace; 1289 1290 MPASS(j < LOCK_CHILDCOUNT * LOCK_NCHILDREN); 1291 lock1 = &lle->ll_children[i]; 1292 1293 /* 1294 * Ignore the interlock. 1295 */ 1296 if (interlock == lock1->li_lock) 1297 continue; 1298 1299 /* 1300 * If this lock doesn't undergo witness checking, 1301 * then skip it. 1302 */ 1303 w1 = lock1->li_lock->lo_witness; 1304 if (w1 == NULL) { 1305 KASSERT((lock1->li_lock->lo_flags & LO_WITNESS) == 0, 1306 ("lock missing witness structure")); 1307 continue; 1308 } 1309 1310 /* 1311 * If we are locking Giant and this is a sleepable 1312 * lock, then skip it. 1313 */ 1314 if ((lock1->li_flags & LI_SLEEPABLE) != 0 && 1315 lock == &Giant.lock_object) 1316 continue; 1317 1318 /* 1319 * If we are locking a sleepable lock and this lock 1320 * is Giant, then skip it. 1321 */ 1322 if ((lock->lo_flags & LO_SLEEPABLE) != 0 && 1323 (flags & LOP_NOSLEEP) == 0 && 1324 lock1->li_lock == &Giant.lock_object) 1325 continue; 1326 1327 /* 1328 * If we are locking a sleepable lock and this lock 1329 * isn't sleepable, we want to treat it as a lock 1330 * order violation to enfore a general lock order of 1331 * sleepable locks before non-sleepable locks. 1332 */ 1333 if ((lock->lo_flags & LO_SLEEPABLE) != 0 && 1334 (flags & LOP_NOSLEEP) == 0 && 1335 (lock1->li_flags & LI_SLEEPABLE) == 0) 1336 goto reversal; 1337 1338 /* 1339 * If we are locking Giant and this is a non-sleepable 1340 * lock, then treat it as a reversal. 1341 */ 1342 if ((lock1->li_flags & LI_SLEEPABLE) == 0 && 1343 lock == &Giant.lock_object) 1344 goto reversal; 1345 1346 /* 1347 * Check the lock order hierarchy for a reveresal. 1348 */ 1349 if (!isitmydescendant(w, w1)) 1350 continue; 1351 reversal: 1352 1353 /* 1354 * We have a lock order violation, check to see if it 1355 * is allowed or has already been yelled about. 1356 */ 1357 1358 /* Bail if this violation is known */ 1359 if (w_rmatrix[w1->w_index][w->w_index] & WITNESS_REVERSAL) 1360 goto out; 1361 1362 /* Record this as a violation */ 1363 w_rmatrix[w1->w_index][w->w_index] |= WITNESS_REVERSAL; 1364 w_rmatrix[w->w_index][w1->w_index] |= WITNESS_REVERSAL; 1365 w->w_reversed = w1->w_reversed = 1; 1366 witness_increment_graph_generation(); 1367 1368 /* 1369 * If the lock order is blessed, bail before logging 1370 * anything. We don't look for other lock order 1371 * violations though, which may be a bug. 1372 */ 1373 if (blessed(w, w1)) 1374 goto out; 1375 1376 trace = atomic_load_int(&witness_trace); 1377 if (trace) { 1378 struct witness_lock_order_data *data; 1379 1380 pstackv = false; 1381 data = witness_lock_order_get(w, w1); 1382 if (data != NULL) { 1383 stack_copy(&data->wlod_stack, 1384 &pstack); 1385 pstackv = true; 1386 } 1387 } 1388 mtx_unlock_spin(&w_mtx); 1389 1390 #ifdef WITNESS_NO_VNODE 1391 /* 1392 * There are known LORs between VNODE locks. They are 1393 * not an indication of a bug. VNODE locks are flagged 1394 * as such (LO_IS_VNODE) and we don't yell if the LOR 1395 * is between 2 VNODE locks. 1396 */ 1397 if ((lock->lo_flags & LO_IS_VNODE) != 0 && 1398 (lock1->li_lock->lo_flags & LO_IS_VNODE) != 0) 1399 return; 1400 #endif 1401 1402 /* 1403 * Ok, yell about it. 1404 */ 1405 if ((lock->lo_flags & LO_SLEEPABLE) != 0 && 1406 (flags & LOP_NOSLEEP) == 0 && 1407 (lock1->li_flags & LI_SLEEPABLE) == 0) 1408 witness_output( 1409 "lock order reversal: (sleepable after non-sleepable)\n"); 1410 else if ((lock1->li_flags & LI_SLEEPABLE) == 0 1411 && lock == &Giant.lock_object) 1412 witness_output( 1413 "lock order reversal: (Giant after non-sleepable)\n"); 1414 else 1415 witness_output("lock order reversal:\n"); 1416 1417 /* 1418 * Try to locate an earlier lock with 1419 * witness w in our list. 1420 */ 1421 do { 1422 lock2 = &lle->ll_children[i]; 1423 MPASS(lock2->li_lock != NULL); 1424 if (lock2->li_lock->lo_witness == w) 1425 break; 1426 if (i == 0 && lle->ll_next != NULL) { 1427 lle = lle->ll_next; 1428 i = lle->ll_count - 1; 1429 MPASS(i >= 0 && i < LOCK_NCHILDREN); 1430 } else 1431 i--; 1432 } while (i >= 0); 1433 if (i < 0) { 1434 witness_output(" 1st %p %s (%s, %s) @ %s:%d\n", 1435 lock1->li_lock, lock1->li_lock->lo_name, 1436 w1->w_name, w1->w_class->lc_name, 1437 fixup_filename(lock1->li_file), 1438 lock1->li_line); 1439 witness_output(" 2nd %p %s (%s, %s) @ %s:%d\n", 1440 lock, lock->lo_name, w->w_name, 1441 w->w_class->lc_name, fixup_filename(file), 1442 line); 1443 } else { 1444 struct witness *w2 = lock2->li_lock->lo_witness; 1445 1446 witness_output(" 1st %p %s (%s, %s) @ %s:%d\n", 1447 lock2->li_lock, lock2->li_lock->lo_name, 1448 w2->w_name, w2->w_class->lc_name, 1449 fixup_filename(lock2->li_file), 1450 lock2->li_line); 1451 witness_output(" 2nd %p %s (%s, %s) @ %s:%d\n", 1452 lock1->li_lock, lock1->li_lock->lo_name, 1453 w1->w_name, w1->w_class->lc_name, 1454 fixup_filename(lock1->li_file), 1455 lock1->li_line); 1456 witness_output(" 3rd %p %s (%s, %s) @ %s:%d\n", lock, 1457 lock->lo_name, w->w_name, 1458 w->w_class->lc_name, fixup_filename(file), 1459 line); 1460 } 1461 if (trace) { 1462 char buf[64]; 1463 struct sbuf sb; 1464 1465 sbuf_new(&sb, buf, sizeof(buf), SBUF_FIXEDLEN); 1466 sbuf_set_drain(&sb, witness_output_drain, 1467 NULL); 1468 1469 if (pstackv) { 1470 sbuf_printf(&sb, 1471 "lock order %s -> %s established at:\n", 1472 w->w_name, w1->w_name); 1473 stack_sbuf_print_flags(&sb, &pstack, 1474 M_NOWAIT, STACK_SBUF_FMT_LONG); 1475 } 1476 1477 sbuf_printf(&sb, 1478 "lock order %s -> %s attempted at:\n", 1479 w1->w_name, w->w_name); 1480 stack_save(&pstack); 1481 stack_sbuf_print_flags(&sb, &pstack, M_NOWAIT, 1482 STACK_SBUF_FMT_LONG); 1483 1484 sbuf_finish(&sb); 1485 sbuf_delete(&sb); 1486 } 1487 witness_enter_debugger(__func__); 1488 return; 1489 } 1490 } 1491 1492 /* 1493 * If requested, build a new lock order. However, don't build a new 1494 * relationship between a sleepable lock and Giant if it is in the 1495 * wrong direction. The correct lock order is that sleepable locks 1496 * always come before Giant. 1497 */ 1498 if (flags & LOP_NEWORDER && 1499 !(plock->li_lock == &Giant.lock_object && 1500 (lock->lo_flags & LO_SLEEPABLE) != 0 && 1501 (flags & LOP_NOSLEEP) == 0)) { 1502 CTR3(KTR_WITNESS, "%s: adding %s as a child of %s", __func__, 1503 w->w_name, plock->li_lock->lo_witness->w_name); 1504 itismychild(plock->li_lock->lo_witness, w); 1505 } 1506 out: 1507 mtx_unlock_spin(&w_mtx); 1508 } 1509 1510 void 1511 witness_lock(struct lock_object *lock, int flags, const char *file, int line) 1512 { 1513 struct lock_list_entry **lock_list, *lle; 1514 struct lock_instance *instance; 1515 struct witness *w; 1516 struct thread *td; 1517 1518 if (witness_cold || witness_watch == -1 || lock->lo_witness == NULL || 1519 KERNEL_PANICKED()) 1520 return; 1521 w = lock->lo_witness; 1522 td = curthread; 1523 1524 /* Determine lock list for this lock. */ 1525 if (LOCK_CLASS(lock)->lc_flags & LC_SLEEPLOCK) 1526 lock_list = &td->td_sleeplocks; 1527 else 1528 lock_list = PCPU_PTR(spinlocks); 1529 1530 /* Check to see if we are recursing on a lock we already own. */ 1531 instance = find_instance(*lock_list, lock); 1532 if (instance != NULL) { 1533 instance->li_flags++; 1534 CTR4(KTR_WITNESS, "%s: pid %d recursed on %s r=%d", __func__, 1535 td->td_proc->p_pid, lock->lo_name, 1536 instance->li_flags & LI_RECURSEMASK); 1537 instance->li_file = file; 1538 instance->li_line = line; 1539 return; 1540 } 1541 1542 /* Update per-witness last file and line acquire. */ 1543 w->w_file = file; 1544 w->w_line = line; 1545 1546 /* Find the next open lock instance in the list and fill it. */ 1547 lle = *lock_list; 1548 if (lle == NULL || lle->ll_count == LOCK_NCHILDREN) { 1549 lle = witness_lock_list_get(); 1550 if (lle == NULL) 1551 return; 1552 lle->ll_next = *lock_list; 1553 CTR3(KTR_WITNESS, "%s: pid %d added lle %p", __func__, 1554 td->td_proc->p_pid, lle); 1555 *lock_list = lle; 1556 } 1557 instance = &lle->ll_children[lle->ll_count++]; 1558 instance->li_lock = lock; 1559 instance->li_line = line; 1560 instance->li_file = file; 1561 instance->li_flags = 0; 1562 if ((flags & LOP_EXCLUSIVE) != 0) 1563 instance->li_flags |= LI_EXCLUSIVE; 1564 if ((lock->lo_flags & LO_SLEEPABLE) != 0 && (flags & LOP_NOSLEEP) == 0) 1565 instance->li_flags |= LI_SLEEPABLE; 1566 CTR4(KTR_WITNESS, "%s: pid %d added %s as lle[%d]", __func__, 1567 td->td_proc->p_pid, lock->lo_name, lle->ll_count - 1); 1568 } 1569 1570 void 1571 witness_upgrade(struct lock_object *lock, int flags, const char *file, int line) 1572 { 1573 struct lock_instance *instance; 1574 struct lock_class *class; 1575 1576 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); 1577 if (lock->lo_witness == NULL || witness_watch == -1 || KERNEL_PANICKED()) 1578 return; 1579 class = LOCK_CLASS(lock); 1580 if (witness_watch) { 1581 if ((lock->lo_flags & LO_UPGRADABLE) == 0) 1582 kassert_panic( 1583 "upgrade of non-upgradable lock (%s) %s @ %s:%d", 1584 class->lc_name, lock->lo_name, 1585 fixup_filename(file), line); 1586 if ((class->lc_flags & LC_SLEEPLOCK) == 0) 1587 kassert_panic( 1588 "upgrade of non-sleep lock (%s) %s @ %s:%d", 1589 class->lc_name, lock->lo_name, 1590 fixup_filename(file), line); 1591 } 1592 instance = find_instance(curthread->td_sleeplocks, lock); 1593 if (instance == NULL) { 1594 kassert_panic("upgrade of unlocked lock (%s) %s @ %s:%d", 1595 class->lc_name, lock->lo_name, 1596 fixup_filename(file), line); 1597 return; 1598 } 1599 if (witness_watch) { 1600 if ((instance->li_flags & LI_EXCLUSIVE) != 0) 1601 kassert_panic( 1602 "upgrade of exclusive lock (%s) %s @ %s:%d", 1603 class->lc_name, lock->lo_name, 1604 fixup_filename(file), line); 1605 if ((instance->li_flags & LI_RECURSEMASK) != 0) 1606 kassert_panic( 1607 "upgrade of recursed lock (%s) %s r=%d @ %s:%d", 1608 class->lc_name, lock->lo_name, 1609 instance->li_flags & LI_RECURSEMASK, 1610 fixup_filename(file), line); 1611 } 1612 instance->li_flags |= LI_EXCLUSIVE; 1613 } 1614 1615 void 1616 witness_downgrade(struct lock_object *lock, int flags, const char *file, 1617 int line) 1618 { 1619 struct lock_instance *instance; 1620 struct lock_class *class; 1621 1622 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); 1623 if (lock->lo_witness == NULL || witness_watch == -1 || KERNEL_PANICKED()) 1624 return; 1625 class = LOCK_CLASS(lock); 1626 if (witness_watch) { 1627 if ((lock->lo_flags & LO_UPGRADABLE) == 0) 1628 kassert_panic( 1629 "downgrade of non-upgradable lock (%s) %s @ %s:%d", 1630 class->lc_name, lock->lo_name, 1631 fixup_filename(file), line); 1632 if ((class->lc_flags & LC_SLEEPLOCK) == 0) 1633 kassert_panic( 1634 "downgrade of non-sleep lock (%s) %s @ %s:%d", 1635 class->lc_name, lock->lo_name, 1636 fixup_filename(file), line); 1637 } 1638 instance = find_instance(curthread->td_sleeplocks, lock); 1639 if (instance == NULL) { 1640 kassert_panic("downgrade of unlocked lock (%s) %s @ %s:%d", 1641 class->lc_name, lock->lo_name, 1642 fixup_filename(file), line); 1643 return; 1644 } 1645 if (witness_watch) { 1646 if ((instance->li_flags & LI_EXCLUSIVE) == 0) 1647 kassert_panic( 1648 "downgrade of shared lock (%s) %s @ %s:%d", 1649 class->lc_name, lock->lo_name, 1650 fixup_filename(file), line); 1651 if ((instance->li_flags & LI_RECURSEMASK) != 0) 1652 kassert_panic( 1653 "downgrade of recursed lock (%s) %s r=%d @ %s:%d", 1654 class->lc_name, lock->lo_name, 1655 instance->li_flags & LI_RECURSEMASK, 1656 fixup_filename(file), line); 1657 } 1658 instance->li_flags &= ~LI_EXCLUSIVE; 1659 } 1660 1661 void 1662 witness_unlock(struct lock_object *lock, int flags, const char *file, int line) 1663 { 1664 struct lock_list_entry **lock_list, *lle; 1665 struct lock_instance *instance; 1666 struct lock_class *class; 1667 struct thread *td; 1668 register_t s; 1669 int i, j; 1670 1671 if (witness_cold || lock->lo_witness == NULL || KERNEL_PANICKED()) 1672 return; 1673 td = curthread; 1674 class = LOCK_CLASS(lock); 1675 1676 /* Find lock instance associated with this lock. */ 1677 if (class->lc_flags & LC_SLEEPLOCK) 1678 lock_list = &td->td_sleeplocks; 1679 else 1680 lock_list = PCPU_PTR(spinlocks); 1681 lle = *lock_list; 1682 for (; *lock_list != NULL; lock_list = &(*lock_list)->ll_next) 1683 for (i = 0; i < (*lock_list)->ll_count; i++) { 1684 instance = &(*lock_list)->ll_children[i]; 1685 if (instance->li_lock == lock) 1686 goto found; 1687 } 1688 1689 /* 1690 * When disabling WITNESS through witness_watch we could end up in 1691 * having registered locks in the td_sleeplocks queue. 1692 * We have to make sure we flush these queues, so just search for 1693 * eventual register locks and remove them. 1694 */ 1695 if (witness_watch > 0) { 1696 kassert_panic("lock (%s) %s not locked @ %s:%d", class->lc_name, 1697 lock->lo_name, fixup_filename(file), line); 1698 return; 1699 } else { 1700 return; 1701 } 1702 found: 1703 1704 /* First, check for shared/exclusive mismatches. */ 1705 if ((instance->li_flags & LI_EXCLUSIVE) != 0 && witness_watch > 0 && 1706 (flags & LOP_EXCLUSIVE) == 0) { 1707 witness_output("shared unlock of (%s) %s @ %s:%d\n", 1708 class->lc_name, lock->lo_name, fixup_filename(file), line); 1709 witness_output("while exclusively locked from %s:%d\n", 1710 fixup_filename(instance->li_file), instance->li_line); 1711 kassert_panic("excl->ushare"); 1712 } 1713 if ((instance->li_flags & LI_EXCLUSIVE) == 0 && witness_watch > 0 && 1714 (flags & LOP_EXCLUSIVE) != 0) { 1715 witness_output("exclusive unlock of (%s) %s @ %s:%d\n", 1716 class->lc_name, lock->lo_name, fixup_filename(file), line); 1717 witness_output("while share locked from %s:%d\n", 1718 fixup_filename(instance->li_file), 1719 instance->li_line); 1720 kassert_panic("share->uexcl"); 1721 } 1722 /* If we are recursed, unrecurse. */ 1723 if ((instance->li_flags & LI_RECURSEMASK) > 0) { 1724 CTR4(KTR_WITNESS, "%s: pid %d unrecursed on %s r=%d", __func__, 1725 td->td_proc->p_pid, instance->li_lock->lo_name, 1726 instance->li_flags); 1727 instance->li_flags--; 1728 return; 1729 } 1730 /* The lock is now being dropped, check for NORELEASE flag */ 1731 if ((instance->li_flags & LI_NORELEASE) != 0 && witness_watch > 0) { 1732 witness_output("forbidden unlock of (%s) %s @ %s:%d\n", 1733 class->lc_name, lock->lo_name, fixup_filename(file), line); 1734 kassert_panic("lock marked norelease"); 1735 } 1736 1737 /* Otherwise, remove this item from the list. */ 1738 s = intr_disable(); 1739 CTR4(KTR_WITNESS, "%s: pid %d removed %s from lle[%d]", __func__, 1740 td->td_proc->p_pid, instance->li_lock->lo_name, 1741 (*lock_list)->ll_count - 1); 1742 for (j = i; j < (*lock_list)->ll_count - 1; j++) 1743 (*lock_list)->ll_children[j] = 1744 (*lock_list)->ll_children[j + 1]; 1745 (*lock_list)->ll_count--; 1746 intr_restore(s); 1747 1748 /* 1749 * In order to reduce contention on w_mtx, we want to keep always an 1750 * head object into lists so that frequent allocation from the 1751 * free witness pool (and subsequent locking) is avoided. 1752 * In order to maintain the current code simple, when the head 1753 * object is totally unloaded it means also that we do not have 1754 * further objects in the list, so the list ownership needs to be 1755 * hand over to another object if the current head needs to be freed. 1756 */ 1757 if ((*lock_list)->ll_count == 0) { 1758 if (*lock_list == lle) { 1759 if (lle->ll_next == NULL) 1760 return; 1761 } else 1762 lle = *lock_list; 1763 *lock_list = lle->ll_next; 1764 CTR3(KTR_WITNESS, "%s: pid %d removed lle %p", __func__, 1765 td->td_proc->p_pid, lle); 1766 witness_lock_list_free(lle); 1767 } 1768 } 1769 1770 void 1771 witness_thread_exit(struct thread *td) 1772 { 1773 struct lock_list_entry *lle; 1774 int i, n; 1775 1776 lle = td->td_sleeplocks; 1777 if (lle == NULL || KERNEL_PANICKED()) 1778 return; 1779 if (lle->ll_count != 0) { 1780 for (n = 0; lle != NULL; lle = lle->ll_next) 1781 for (i = lle->ll_count - 1; i >= 0; i--) { 1782 if (n == 0) 1783 witness_output( 1784 "Thread %p exiting with the following locks held:\n", td); 1785 n++; 1786 witness_list_lock(&lle->ll_children[i], 1787 witness_output); 1788 1789 } 1790 kassert_panic( 1791 "Thread %p cannot exit while holding sleeplocks\n", td); 1792 } 1793 witness_lock_list_free(lle); 1794 } 1795 1796 /* 1797 * Warn if any locks other than 'lock' are held. Flags can be passed in to 1798 * exempt Giant and sleepable locks from the checks as well. If any 1799 * non-exempt locks are held, then a supplied message is printed to the 1800 * output channel along with a list of the offending locks. If indicated in the 1801 * flags then a failure results in a panic as well. 1802 */ 1803 int 1804 witness_warn(int flags, struct lock_object *lock, const char *fmt, ...) 1805 { 1806 struct lock_list_entry *lock_list, *lle; 1807 struct lock_instance *lock1; 1808 struct thread *td; 1809 va_list ap; 1810 int i, n; 1811 1812 if (witness_cold || witness_watch < 1 || KERNEL_PANICKED()) 1813 return (0); 1814 n = 0; 1815 td = curthread; 1816 for (lle = td->td_sleeplocks; lle != NULL; lle = lle->ll_next) 1817 for (i = lle->ll_count - 1; i >= 0; i--) { 1818 lock1 = &lle->ll_children[i]; 1819 if (lock1->li_lock == lock) 1820 continue; 1821 if (flags & WARN_GIANTOK && 1822 lock1->li_lock == &Giant.lock_object) 1823 continue; 1824 if (flags & WARN_SLEEPOK && 1825 (lock1->li_flags & LI_SLEEPABLE) != 0) 1826 continue; 1827 if (n == 0) { 1828 va_start(ap, fmt); 1829 vprintf(fmt, ap); 1830 va_end(ap); 1831 printf(" with the following %slocks held:\n", 1832 (flags & WARN_SLEEPOK) != 0 ? 1833 "non-sleepable " : ""); 1834 } 1835 n++; 1836 witness_list_lock(lock1, printf); 1837 } 1838 1839 /* 1840 * Pin the thread in order to avoid problems with thread migration. 1841 * Once that all verifies are passed about spinlocks ownership, 1842 * the thread is in a safe path and it can be unpinned. 1843 */ 1844 sched_pin(); 1845 lock_list = PCPU_GET(spinlocks); 1846 if (lock_list != NULL && lock_list->ll_count != 0) { 1847 sched_unpin(); 1848 1849 /* 1850 * We should only have one spinlock and as long as 1851 * the flags cannot match for this locks class, 1852 * check if the first spinlock is the one curthread 1853 * should hold. 1854 */ 1855 lock1 = &lock_list->ll_children[lock_list->ll_count - 1]; 1856 if (lock_list->ll_count == 1 && lock_list->ll_next == NULL && 1857 lock1->li_lock == lock && n == 0) 1858 return (0); 1859 1860 va_start(ap, fmt); 1861 vprintf(fmt, ap); 1862 va_end(ap); 1863 printf(" with the following %slocks held:\n", 1864 (flags & WARN_SLEEPOK) != 0 ? "non-sleepable " : ""); 1865 n += witness_list_locks(&lock_list, printf); 1866 } else 1867 sched_unpin(); 1868 if (flags & WARN_PANIC && n) 1869 kassert_panic("%s", __func__); 1870 else 1871 witness_debugger(n, __func__); 1872 return (n); 1873 } 1874 1875 const char * 1876 witness_file(struct lock_object *lock) 1877 { 1878 struct witness *w; 1879 1880 if (witness_cold || witness_watch < 1 || lock->lo_witness == NULL) 1881 return ("?"); 1882 w = lock->lo_witness; 1883 return (w->w_file); 1884 } 1885 1886 int 1887 witness_line(struct lock_object *lock) 1888 { 1889 struct witness *w; 1890 1891 if (witness_cold || witness_watch < 1 || lock->lo_witness == NULL) 1892 return (0); 1893 w = lock->lo_witness; 1894 return (w->w_line); 1895 } 1896 1897 static struct witness * 1898 enroll(const char *description, struct lock_class *lock_class) 1899 { 1900 struct witness *w; 1901 1902 MPASS(description != NULL); 1903 1904 if (witness_watch == -1 || KERNEL_PANICKED()) 1905 return (NULL); 1906 if ((lock_class->lc_flags & LC_SPINLOCK)) { 1907 if (witness_skipspin) 1908 return (NULL); 1909 } else if ((lock_class->lc_flags & LC_SLEEPLOCK) == 0) { 1910 kassert_panic("lock class %s is not sleep or spin", 1911 lock_class->lc_name); 1912 return (NULL); 1913 } 1914 1915 mtx_lock_spin(&w_mtx); 1916 w = witness_hash_get(description); 1917 if (w) 1918 goto found; 1919 if ((w = witness_get()) == NULL) 1920 return (NULL); 1921 MPASS(strlen(description) < MAX_W_NAME); 1922 strcpy(w->w_name, description); 1923 w->w_class = lock_class; 1924 w->w_refcount = 1; 1925 STAILQ_INSERT_HEAD(&w_all, w, w_list); 1926 if (lock_class->lc_flags & LC_SPINLOCK) { 1927 STAILQ_INSERT_HEAD(&w_spin, w, w_typelist); 1928 w_spin_cnt++; 1929 } else if (lock_class->lc_flags & LC_SLEEPLOCK) { 1930 STAILQ_INSERT_HEAD(&w_sleep, w, w_typelist); 1931 w_sleep_cnt++; 1932 } 1933 1934 /* Insert new witness into the hash */ 1935 witness_hash_put(w); 1936 witness_increment_graph_generation(); 1937 mtx_unlock_spin(&w_mtx); 1938 return (w); 1939 found: 1940 w->w_refcount++; 1941 if (w->w_refcount == 1) 1942 w->w_class = lock_class; 1943 mtx_unlock_spin(&w_mtx); 1944 if (lock_class != w->w_class) 1945 kassert_panic( 1946 "lock (%s) %s does not match earlier (%s) lock", 1947 description, lock_class->lc_name, 1948 w->w_class->lc_name); 1949 return (w); 1950 } 1951 1952 static void 1953 depart(struct witness *w) 1954 { 1955 1956 MPASS(w->w_refcount == 0); 1957 if (w->w_class->lc_flags & LC_SLEEPLOCK) { 1958 w_sleep_cnt--; 1959 } else { 1960 w_spin_cnt--; 1961 } 1962 /* 1963 * Set file to NULL as it may point into a loadable module. 1964 */ 1965 w->w_file = NULL; 1966 w->w_line = 0; 1967 witness_increment_graph_generation(); 1968 } 1969 1970 static void 1971 adopt(struct witness *parent, struct witness *child) 1972 { 1973 int pi, ci, i, j; 1974 1975 if (witness_cold == 0) 1976 mtx_assert(&w_mtx, MA_OWNED); 1977 1978 /* If the relationship is already known, there's no work to be done. */ 1979 if (isitmychild(parent, child)) 1980 return; 1981 1982 /* When the structure of the graph changes, bump up the generation. */ 1983 witness_increment_graph_generation(); 1984 1985 /* 1986 * The hard part ... create the direct relationship, then propagate all 1987 * indirect relationships. 1988 */ 1989 pi = parent->w_index; 1990 ci = child->w_index; 1991 WITNESS_INDEX_ASSERT(pi); 1992 WITNESS_INDEX_ASSERT(ci); 1993 MPASS(pi != ci); 1994 w_rmatrix[pi][ci] |= WITNESS_PARENT; 1995 w_rmatrix[ci][pi] |= WITNESS_CHILD; 1996 1997 /* 1998 * If parent was not already an ancestor of child, 1999 * then we increment the descendant and ancestor counters. 2000 */ 2001 if ((w_rmatrix[pi][ci] & WITNESS_ANCESTOR) == 0) { 2002 parent->w_num_descendants++; 2003 child->w_num_ancestors++; 2004 } 2005 2006 /* 2007 * Find each ancestor of 'pi'. Note that 'pi' itself is counted as 2008 * an ancestor of 'pi' during this loop. 2009 */ 2010 for (i = 1; i <= w_max_used_index; i++) { 2011 if ((w_rmatrix[i][pi] & WITNESS_ANCESTOR_MASK) == 0 && 2012 (i != pi)) 2013 continue; 2014 2015 /* Find each descendant of 'i' and mark it as a descendant. */ 2016 for (j = 1; j <= w_max_used_index; j++) { 2017 2018 /* 2019 * Skip children that are already marked as 2020 * descendants of 'i'. 2021 */ 2022 if (w_rmatrix[i][j] & WITNESS_ANCESTOR_MASK) 2023 continue; 2024 2025 /* 2026 * We are only interested in descendants of 'ci'. Note 2027 * that 'ci' itself is counted as a descendant of 'ci'. 2028 */ 2029 if ((w_rmatrix[ci][j] & WITNESS_ANCESTOR_MASK) == 0 && 2030 (j != ci)) 2031 continue; 2032 w_rmatrix[i][j] |= WITNESS_ANCESTOR; 2033 w_rmatrix[j][i] |= WITNESS_DESCENDANT; 2034 w_data[i].w_num_descendants++; 2035 w_data[j].w_num_ancestors++; 2036 2037 /* 2038 * Make sure we aren't marking a node as both an 2039 * ancestor and descendant. We should have caught 2040 * this as a lock order reversal earlier. 2041 */ 2042 if ((w_rmatrix[i][j] & WITNESS_ANCESTOR_MASK) && 2043 (w_rmatrix[i][j] & WITNESS_DESCENDANT_MASK)) { 2044 printf("witness rmatrix paradox! [%d][%d]=%d " 2045 "both ancestor and descendant\n", 2046 i, j, w_rmatrix[i][j]); 2047 kdb_backtrace(); 2048 printf("Witness disabled.\n"); 2049 witness_watch = -1; 2050 } 2051 if ((w_rmatrix[j][i] & WITNESS_ANCESTOR_MASK) && 2052 (w_rmatrix[j][i] & WITNESS_DESCENDANT_MASK)) { 2053 printf("witness rmatrix paradox! [%d][%d]=%d " 2054 "both ancestor and descendant\n", 2055 j, i, w_rmatrix[j][i]); 2056 kdb_backtrace(); 2057 printf("Witness disabled.\n"); 2058 witness_watch = -1; 2059 } 2060 } 2061 } 2062 } 2063 2064 static void 2065 itismychild(struct witness *parent, struct witness *child) 2066 { 2067 int unlocked; 2068 2069 MPASS(child != NULL && parent != NULL); 2070 if (witness_cold == 0) 2071 mtx_assert(&w_mtx, MA_OWNED); 2072 2073 if (!witness_lock_type_equal(parent, child)) { 2074 if (witness_cold == 0) { 2075 unlocked = 1; 2076 mtx_unlock_spin(&w_mtx); 2077 } else { 2078 unlocked = 0; 2079 } 2080 kassert_panic( 2081 "%s: parent \"%s\" (%s) and child \"%s\" (%s) are not " 2082 "the same lock type", __func__, parent->w_name, 2083 parent->w_class->lc_name, child->w_name, 2084 child->w_class->lc_name); 2085 if (unlocked) 2086 mtx_lock_spin(&w_mtx); 2087 } 2088 adopt(parent, child); 2089 } 2090 2091 /* 2092 * Generic code for the isitmy*() functions. The rmask parameter is the 2093 * expected relationship of w1 to w2. 2094 */ 2095 static int 2096 _isitmyx(struct witness *w1, struct witness *w2, int rmask, const char *fname) 2097 { 2098 unsigned char r1, r2; 2099 int i1, i2; 2100 2101 i1 = w1->w_index; 2102 i2 = w2->w_index; 2103 WITNESS_INDEX_ASSERT(i1); 2104 WITNESS_INDEX_ASSERT(i2); 2105 r1 = w_rmatrix[i1][i2] & WITNESS_RELATED_MASK; 2106 r2 = w_rmatrix[i2][i1] & WITNESS_RELATED_MASK; 2107 2108 /* The flags on one better be the inverse of the flags on the other */ 2109 if (!((WITNESS_ATOD(r1) == r2 && WITNESS_DTOA(r2) == r1) || 2110 (WITNESS_DTOA(r1) == r2 && WITNESS_ATOD(r2) == r1))) { 2111 /* Don't squawk if we're potentially racing with an update. */ 2112 if (!mtx_owned(&w_mtx)) 2113 return (0); 2114 printf("%s: rmatrix mismatch between %s (index %d) and %s " 2115 "(index %d): w_rmatrix[%d][%d] == %hhx but " 2116 "w_rmatrix[%d][%d] == %hhx\n", 2117 fname, w1->w_name, i1, w2->w_name, i2, i1, i2, r1, 2118 i2, i1, r2); 2119 kdb_backtrace(); 2120 printf("Witness disabled.\n"); 2121 witness_watch = -1; 2122 } 2123 return (r1 & rmask); 2124 } 2125 2126 /* 2127 * Checks if @child is a direct child of @parent. 2128 */ 2129 static int 2130 isitmychild(struct witness *parent, struct witness *child) 2131 { 2132 2133 return (_isitmyx(parent, child, WITNESS_PARENT, __func__)); 2134 } 2135 2136 /* 2137 * Checks if @descendant is a direct or inderect descendant of @ancestor. 2138 */ 2139 static int 2140 isitmydescendant(struct witness *ancestor, struct witness *descendant) 2141 { 2142 2143 return (_isitmyx(ancestor, descendant, WITNESS_ANCESTOR_MASK, 2144 __func__)); 2145 } 2146 2147 static int 2148 blessed(struct witness *w1, struct witness *w2) 2149 { 2150 int i; 2151 struct witness_blessed *b; 2152 2153 for (i = 0; i < nitems(blessed_list); i++) { 2154 b = &blessed_list[i]; 2155 if (strcmp(w1->w_name, b->b_lock1) == 0) { 2156 if (strcmp(w2->w_name, b->b_lock2) == 0) 2157 return (1); 2158 continue; 2159 } 2160 if (strcmp(w1->w_name, b->b_lock2) == 0) 2161 if (strcmp(w2->w_name, b->b_lock1) == 0) 2162 return (1); 2163 } 2164 return (0); 2165 } 2166 2167 static struct witness * 2168 witness_get(void) 2169 { 2170 struct witness *w; 2171 int index; 2172 2173 if (witness_cold == 0) 2174 mtx_assert(&w_mtx, MA_OWNED); 2175 2176 if (witness_watch == -1) { 2177 mtx_unlock_spin(&w_mtx); 2178 return (NULL); 2179 } 2180 if (STAILQ_EMPTY(&w_free)) { 2181 witness_watch = -1; 2182 mtx_unlock_spin(&w_mtx); 2183 printf("WITNESS: unable to allocate a new witness object\n"); 2184 return (NULL); 2185 } 2186 w = STAILQ_FIRST(&w_free); 2187 STAILQ_REMOVE_HEAD(&w_free, w_list); 2188 w_free_cnt--; 2189 index = w->w_index; 2190 MPASS(index > 0 && index == w_max_used_index+1 && 2191 index < witness_count); 2192 bzero(w, sizeof(*w)); 2193 w->w_index = index; 2194 if (index > w_max_used_index) 2195 w_max_used_index = index; 2196 return (w); 2197 } 2198 2199 static void 2200 witness_free(struct witness *w) 2201 { 2202 2203 STAILQ_INSERT_HEAD(&w_free, w, w_list); 2204 w_free_cnt++; 2205 } 2206 2207 static struct lock_list_entry * 2208 witness_lock_list_get(void) 2209 { 2210 struct lock_list_entry *lle; 2211 2212 if (witness_watch == -1) 2213 return (NULL); 2214 mtx_lock_spin(&w_mtx); 2215 lle = w_lock_list_free; 2216 if (lle == NULL) { 2217 witness_watch = -1; 2218 mtx_unlock_spin(&w_mtx); 2219 printf("%s: witness exhausted\n", __func__); 2220 return (NULL); 2221 } 2222 w_lock_list_free = lle->ll_next; 2223 mtx_unlock_spin(&w_mtx); 2224 bzero(lle, sizeof(*lle)); 2225 return (lle); 2226 } 2227 2228 static void 2229 witness_lock_list_free(struct lock_list_entry *lle) 2230 { 2231 2232 mtx_lock_spin(&w_mtx); 2233 lle->ll_next = w_lock_list_free; 2234 w_lock_list_free = lle; 2235 mtx_unlock_spin(&w_mtx); 2236 } 2237 2238 static struct lock_instance * 2239 find_instance(struct lock_list_entry *list, const struct lock_object *lock) 2240 { 2241 struct lock_list_entry *lle; 2242 struct lock_instance *instance; 2243 int i; 2244 2245 for (lle = list; lle != NULL; lle = lle->ll_next) 2246 for (i = lle->ll_count - 1; i >= 0; i--) { 2247 instance = &lle->ll_children[i]; 2248 if (instance->li_lock == lock) 2249 return (instance); 2250 } 2251 return (NULL); 2252 } 2253 2254 static void 2255 witness_list_lock(struct lock_instance *instance, 2256 int (*prnt)(const char *fmt, ...)) 2257 { 2258 struct lock_object *lock; 2259 2260 lock = instance->li_lock; 2261 prnt("%s %s %s", (instance->li_flags & LI_EXCLUSIVE) != 0 ? 2262 "exclusive" : "shared", LOCK_CLASS(lock)->lc_name, lock->lo_name); 2263 if (lock->lo_witness->w_name != lock->lo_name) 2264 prnt(" (%s)", lock->lo_witness->w_name); 2265 prnt(" r = %d (%p) locked @ %s:%d\n", 2266 instance->li_flags & LI_RECURSEMASK, lock, 2267 fixup_filename(instance->li_file), instance->li_line); 2268 } 2269 2270 static int 2271 witness_output(const char *fmt, ...) 2272 { 2273 va_list ap; 2274 int ret; 2275 2276 va_start(ap, fmt); 2277 ret = witness_voutput(fmt, ap); 2278 va_end(ap); 2279 return (ret); 2280 } 2281 2282 static int 2283 witness_voutput(const char *fmt, va_list ap) 2284 { 2285 int ret; 2286 2287 ret = 0; 2288 switch (witness_channel) { 2289 case WITNESS_CONSOLE: 2290 ret = vprintf(fmt, ap); 2291 break; 2292 case WITNESS_LOG: 2293 vlog(LOG_NOTICE, fmt, ap); 2294 break; 2295 case WITNESS_NONE: 2296 break; 2297 } 2298 return (ret); 2299 } 2300 2301 #ifdef DDB 2302 static int 2303 witness_thread_has_locks(struct thread *td) 2304 { 2305 2306 if (td->td_sleeplocks == NULL) 2307 return (0); 2308 return (td->td_sleeplocks->ll_count != 0); 2309 } 2310 2311 static int 2312 witness_proc_has_locks(struct proc *p) 2313 { 2314 struct thread *td; 2315 2316 FOREACH_THREAD_IN_PROC(p, td) { 2317 if (witness_thread_has_locks(td)) 2318 return (1); 2319 } 2320 return (0); 2321 } 2322 #endif 2323 2324 int 2325 witness_list_locks(struct lock_list_entry **lock_list, 2326 int (*prnt)(const char *fmt, ...)) 2327 { 2328 struct lock_list_entry *lle; 2329 int i, nheld; 2330 2331 nheld = 0; 2332 for (lle = *lock_list; lle != NULL; lle = lle->ll_next) 2333 for (i = lle->ll_count - 1; i >= 0; i--) { 2334 witness_list_lock(&lle->ll_children[i], prnt); 2335 nheld++; 2336 } 2337 return (nheld); 2338 } 2339 2340 /* 2341 * This is a bit risky at best. We call this function when we have timed 2342 * out acquiring a spin lock, and we assume that the other CPU is stuck 2343 * with this lock held. So, we go groveling around in the other CPU's 2344 * per-cpu data to try to find the lock instance for this spin lock to 2345 * see when it was last acquired. 2346 */ 2347 void 2348 witness_display_spinlock(struct lock_object *lock, struct thread *owner, 2349 int (*prnt)(const char *fmt, ...)) 2350 { 2351 struct lock_instance *instance; 2352 struct pcpu *pc; 2353 2354 if (owner->td_critnest == 0 || owner->td_oncpu == NOCPU) 2355 return; 2356 pc = pcpu_find(owner->td_oncpu); 2357 instance = find_instance(pc->pc_spinlocks, lock); 2358 if (instance != NULL) 2359 witness_list_lock(instance, prnt); 2360 } 2361 2362 void 2363 witness_save(struct lock_object *lock, const char **filep, int *linep) 2364 { 2365 struct lock_list_entry *lock_list; 2366 struct lock_instance *instance; 2367 struct lock_class *class; 2368 2369 /* 2370 * This function is used independently in locking code to deal with 2371 * Giant, SCHEDULER_STOPPED() check can be removed here after Giant 2372 * is gone. 2373 */ 2374 if (SCHEDULER_STOPPED()) 2375 return; 2376 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); 2377 if (lock->lo_witness == NULL || witness_watch == -1 || KERNEL_PANICKED()) 2378 return; 2379 class = LOCK_CLASS(lock); 2380 if (class->lc_flags & LC_SLEEPLOCK) 2381 lock_list = curthread->td_sleeplocks; 2382 else { 2383 if (witness_skipspin) 2384 return; 2385 lock_list = PCPU_GET(spinlocks); 2386 } 2387 instance = find_instance(lock_list, lock); 2388 if (instance == NULL) { 2389 kassert_panic("%s: lock (%s) %s not locked", __func__, 2390 class->lc_name, lock->lo_name); 2391 return; 2392 } 2393 *filep = instance->li_file; 2394 *linep = instance->li_line; 2395 } 2396 2397 void 2398 witness_restore(struct lock_object *lock, const char *file, int line) 2399 { 2400 struct lock_list_entry *lock_list; 2401 struct lock_instance *instance; 2402 struct lock_class *class; 2403 2404 /* 2405 * This function is used independently in locking code to deal with 2406 * Giant, SCHEDULER_STOPPED() check can be removed here after Giant 2407 * is gone. 2408 */ 2409 if (SCHEDULER_STOPPED()) 2410 return; 2411 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); 2412 if (lock->lo_witness == NULL || witness_watch == -1 || KERNEL_PANICKED()) 2413 return; 2414 class = LOCK_CLASS(lock); 2415 if (class->lc_flags & LC_SLEEPLOCK) 2416 lock_list = curthread->td_sleeplocks; 2417 else { 2418 if (witness_skipspin) 2419 return; 2420 lock_list = PCPU_GET(spinlocks); 2421 } 2422 instance = find_instance(lock_list, lock); 2423 if (instance == NULL) 2424 kassert_panic("%s: lock (%s) %s not locked", __func__, 2425 class->lc_name, lock->lo_name); 2426 lock->lo_witness->w_file = file; 2427 lock->lo_witness->w_line = line; 2428 if (instance == NULL) 2429 return; 2430 instance->li_file = file; 2431 instance->li_line = line; 2432 } 2433 2434 void 2435 witness_assert(const struct lock_object *lock, int flags, const char *file, 2436 int line) 2437 { 2438 #ifdef INVARIANT_SUPPORT 2439 struct lock_instance *instance; 2440 struct lock_class *class; 2441 2442 if (lock->lo_witness == NULL || witness_watch < 1 || KERNEL_PANICKED()) 2443 return; 2444 class = LOCK_CLASS(lock); 2445 if ((class->lc_flags & LC_SLEEPLOCK) != 0) 2446 instance = find_instance(curthread->td_sleeplocks, lock); 2447 else if ((class->lc_flags & LC_SPINLOCK) != 0) 2448 instance = find_instance(PCPU_GET(spinlocks), lock); 2449 else { 2450 kassert_panic("Lock (%s) %s is not sleep or spin!", 2451 class->lc_name, lock->lo_name); 2452 return; 2453 } 2454 switch (flags) { 2455 case LA_UNLOCKED: 2456 if (instance != NULL) 2457 kassert_panic("Lock (%s) %s locked @ %s:%d.", 2458 class->lc_name, lock->lo_name, 2459 fixup_filename(file), line); 2460 break; 2461 case LA_LOCKED: 2462 case LA_LOCKED | LA_RECURSED: 2463 case LA_LOCKED | LA_NOTRECURSED: 2464 case LA_SLOCKED: 2465 case LA_SLOCKED | LA_RECURSED: 2466 case LA_SLOCKED | LA_NOTRECURSED: 2467 case LA_XLOCKED: 2468 case LA_XLOCKED | LA_RECURSED: 2469 case LA_XLOCKED | LA_NOTRECURSED: 2470 if (instance == NULL) { 2471 kassert_panic("Lock (%s) %s not locked @ %s:%d.", 2472 class->lc_name, lock->lo_name, 2473 fixup_filename(file), line); 2474 break; 2475 } 2476 if ((flags & LA_XLOCKED) != 0 && 2477 (instance->li_flags & LI_EXCLUSIVE) == 0) 2478 kassert_panic( 2479 "Lock (%s) %s not exclusively locked @ %s:%d.", 2480 class->lc_name, lock->lo_name, 2481 fixup_filename(file), line); 2482 if ((flags & LA_SLOCKED) != 0 && 2483 (instance->li_flags & LI_EXCLUSIVE) != 0) 2484 kassert_panic( 2485 "Lock (%s) %s exclusively locked @ %s:%d.", 2486 class->lc_name, lock->lo_name, 2487 fixup_filename(file), line); 2488 if ((flags & LA_RECURSED) != 0 && 2489 (instance->li_flags & LI_RECURSEMASK) == 0) 2490 kassert_panic("Lock (%s) %s not recursed @ %s:%d.", 2491 class->lc_name, lock->lo_name, 2492 fixup_filename(file), line); 2493 if ((flags & LA_NOTRECURSED) != 0 && 2494 (instance->li_flags & LI_RECURSEMASK) != 0) 2495 kassert_panic("Lock (%s) %s recursed @ %s:%d.", 2496 class->lc_name, lock->lo_name, 2497 fixup_filename(file), line); 2498 break; 2499 default: 2500 kassert_panic("Invalid lock assertion at %s:%d.", 2501 fixup_filename(file), line); 2502 2503 } 2504 #endif /* INVARIANT_SUPPORT */ 2505 } 2506 2507 static void 2508 witness_setflag(struct lock_object *lock, int flag, int set) 2509 { 2510 struct lock_list_entry *lock_list; 2511 struct lock_instance *instance; 2512 struct lock_class *class; 2513 2514 if (lock->lo_witness == NULL || witness_watch == -1 || KERNEL_PANICKED()) 2515 return; 2516 class = LOCK_CLASS(lock); 2517 if (class->lc_flags & LC_SLEEPLOCK) 2518 lock_list = curthread->td_sleeplocks; 2519 else { 2520 if (witness_skipspin) 2521 return; 2522 lock_list = PCPU_GET(spinlocks); 2523 } 2524 instance = find_instance(lock_list, lock); 2525 if (instance == NULL) { 2526 kassert_panic("%s: lock (%s) %s not locked", __func__, 2527 class->lc_name, lock->lo_name); 2528 return; 2529 } 2530 2531 if (set) 2532 instance->li_flags |= flag; 2533 else 2534 instance->li_flags &= ~flag; 2535 } 2536 2537 void 2538 witness_norelease(struct lock_object *lock) 2539 { 2540 2541 witness_setflag(lock, LI_NORELEASE, 1); 2542 } 2543 2544 void 2545 witness_releaseok(struct lock_object *lock) 2546 { 2547 2548 witness_setflag(lock, LI_NORELEASE, 0); 2549 } 2550 2551 #ifdef DDB 2552 static void 2553 witness_ddb_list(struct thread *td) 2554 { 2555 2556 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); 2557 KASSERT(kdb_active, ("%s: not in the debugger", __func__)); 2558 2559 if (witness_watch < 1) 2560 return; 2561 2562 witness_list_locks(&td->td_sleeplocks, db_printf); 2563 2564 /* 2565 * We only handle spinlocks if td == curthread. This is somewhat broken 2566 * if td is currently executing on some other CPU and holds spin locks 2567 * as we won't display those locks. If we had a MI way of getting 2568 * the per-cpu data for a given cpu then we could use 2569 * td->td_oncpu to get the list of spinlocks for this thread 2570 * and "fix" this. 2571 * 2572 * That still wouldn't really fix this unless we locked the scheduler 2573 * lock or stopped the other CPU to make sure it wasn't changing the 2574 * list out from under us. It is probably best to just not try to 2575 * handle threads on other CPU's for now. 2576 */ 2577 if (td == curthread && PCPU_GET(spinlocks) != NULL) 2578 witness_list_locks(PCPU_PTR(spinlocks), db_printf); 2579 } 2580 2581 DB_SHOW_COMMAND(locks, db_witness_list) 2582 { 2583 struct thread *td; 2584 2585 if (have_addr) 2586 td = db_lookup_thread(addr, true); 2587 else 2588 td = kdb_thread; 2589 witness_ddb_list(td); 2590 } 2591 2592 DB_SHOW_ALL_COMMAND(locks, db_witness_list_all) 2593 { 2594 struct thread *td; 2595 struct proc *p; 2596 2597 /* 2598 * It would be nice to list only threads and processes that actually 2599 * held sleep locks, but that information is currently not exported 2600 * by WITNESS. 2601 */ 2602 FOREACH_PROC_IN_SYSTEM(p) { 2603 if (!witness_proc_has_locks(p)) 2604 continue; 2605 FOREACH_THREAD_IN_PROC(p, td) { 2606 if (!witness_thread_has_locks(td)) 2607 continue; 2608 db_printf("Process %d (%s) thread %p (%d)\n", p->p_pid, 2609 p->p_comm, td, td->td_tid); 2610 witness_ddb_list(td); 2611 if (db_pager_quit) 2612 return; 2613 } 2614 } 2615 } 2616 DB_SHOW_ALIAS(alllocks, db_witness_list_all) 2617 2618 DB_SHOW_COMMAND(witness, db_witness_display) 2619 { 2620 2621 witness_ddb_display(db_printf); 2622 } 2623 #endif 2624 2625 static void 2626 sbuf_print_witness_badstacks(struct sbuf *sb, size_t *oldidx) 2627 { 2628 struct witness_lock_order_data *data1, *data2, *tmp_data1, *tmp_data2; 2629 struct witness *tmp_w1, *tmp_w2, *w1, *w2; 2630 int generation, i, j; 2631 2632 tmp_data1 = NULL; 2633 tmp_data2 = NULL; 2634 tmp_w1 = NULL; 2635 tmp_w2 = NULL; 2636 2637 /* Allocate and init temporary storage space. */ 2638 tmp_w1 = malloc(sizeof(struct witness), M_TEMP, M_WAITOK | M_ZERO); 2639 tmp_w2 = malloc(sizeof(struct witness), M_TEMP, M_WAITOK | M_ZERO); 2640 tmp_data1 = malloc(sizeof(struct witness_lock_order_data), M_TEMP, 2641 M_WAITOK | M_ZERO); 2642 tmp_data2 = malloc(sizeof(struct witness_lock_order_data), M_TEMP, 2643 M_WAITOK | M_ZERO); 2644 stack_zero(&tmp_data1->wlod_stack); 2645 stack_zero(&tmp_data2->wlod_stack); 2646 2647 restart: 2648 mtx_lock_spin(&w_mtx); 2649 generation = w_generation; 2650 mtx_unlock_spin(&w_mtx); 2651 sbuf_printf(sb, "Number of known direct relationships is %d\n", 2652 w_lohash.wloh_count); 2653 for (i = 1; i < w_max_used_index; i++) { 2654 mtx_lock_spin(&w_mtx); 2655 if (generation != w_generation) { 2656 mtx_unlock_spin(&w_mtx); 2657 2658 /* The graph has changed, try again. */ 2659 *oldidx = 0; 2660 sbuf_clear(sb); 2661 goto restart; 2662 } 2663 2664 w1 = &w_data[i]; 2665 if (w1->w_reversed == 0) { 2666 mtx_unlock_spin(&w_mtx); 2667 continue; 2668 } 2669 2670 /* Copy w1 locally so we can release the spin lock. */ 2671 *tmp_w1 = *w1; 2672 mtx_unlock_spin(&w_mtx); 2673 2674 if (tmp_w1->w_reversed == 0) 2675 continue; 2676 for (j = 1; j < w_max_used_index; j++) { 2677 if ((w_rmatrix[i][j] & WITNESS_REVERSAL) == 0 || i > j) 2678 continue; 2679 2680 mtx_lock_spin(&w_mtx); 2681 if (generation != w_generation) { 2682 mtx_unlock_spin(&w_mtx); 2683 2684 /* The graph has changed, try again. */ 2685 *oldidx = 0; 2686 sbuf_clear(sb); 2687 goto restart; 2688 } 2689 2690 w2 = &w_data[j]; 2691 data1 = witness_lock_order_get(w1, w2); 2692 data2 = witness_lock_order_get(w2, w1); 2693 2694 /* 2695 * Copy information locally so we can release the 2696 * spin lock. 2697 */ 2698 *tmp_w2 = *w2; 2699 2700 if (data1) { 2701 stack_zero(&tmp_data1->wlod_stack); 2702 stack_copy(&data1->wlod_stack, 2703 &tmp_data1->wlod_stack); 2704 } 2705 if (data2 && data2 != data1) { 2706 stack_zero(&tmp_data2->wlod_stack); 2707 stack_copy(&data2->wlod_stack, 2708 &tmp_data2->wlod_stack); 2709 } 2710 mtx_unlock_spin(&w_mtx); 2711 2712 if (blessed(tmp_w1, tmp_w2)) 2713 continue; 2714 2715 sbuf_printf(sb, 2716 "\nLock order reversal between \"%s\"(%s) and \"%s\"(%s)!\n", 2717 tmp_w1->w_name, tmp_w1->w_class->lc_name, 2718 tmp_w2->w_name, tmp_w2->w_class->lc_name); 2719 if (data1) { 2720 sbuf_printf(sb, 2721 "Lock order \"%s\"(%s) -> \"%s\"(%s) first seen at:\n", 2722 tmp_w1->w_name, tmp_w1->w_class->lc_name, 2723 tmp_w2->w_name, tmp_w2->w_class->lc_name); 2724 stack_sbuf_print(sb, &tmp_data1->wlod_stack); 2725 sbuf_printf(sb, "\n"); 2726 } 2727 if (data2 && data2 != data1) { 2728 sbuf_printf(sb, 2729 "Lock order \"%s\"(%s) -> \"%s\"(%s) first seen at:\n", 2730 tmp_w2->w_name, tmp_w2->w_class->lc_name, 2731 tmp_w1->w_name, tmp_w1->w_class->lc_name); 2732 stack_sbuf_print(sb, &tmp_data2->wlod_stack); 2733 sbuf_printf(sb, "\n"); 2734 } 2735 } 2736 } 2737 mtx_lock_spin(&w_mtx); 2738 if (generation != w_generation) { 2739 mtx_unlock_spin(&w_mtx); 2740 2741 /* 2742 * The graph changed while we were printing stack data, 2743 * try again. 2744 */ 2745 *oldidx = 0; 2746 sbuf_clear(sb); 2747 goto restart; 2748 } 2749 mtx_unlock_spin(&w_mtx); 2750 2751 /* Free temporary storage space. */ 2752 free(tmp_data1, M_TEMP); 2753 free(tmp_data2, M_TEMP); 2754 free(tmp_w1, M_TEMP); 2755 free(tmp_w2, M_TEMP); 2756 } 2757 2758 static int 2759 sysctl_debug_witness_badstacks(SYSCTL_HANDLER_ARGS) 2760 { 2761 struct sbuf *sb; 2762 int error; 2763 2764 if (witness_watch < 1) { 2765 error = SYSCTL_OUT(req, w_notrunning, sizeof(w_notrunning)); 2766 return (error); 2767 } 2768 if (witness_cold) { 2769 error = SYSCTL_OUT(req, w_stillcold, sizeof(w_stillcold)); 2770 return (error); 2771 } 2772 error = 0; 2773 sb = sbuf_new(NULL, NULL, badstack_sbuf_size, SBUF_AUTOEXTEND); 2774 if (sb == NULL) 2775 return (ENOMEM); 2776 2777 sbuf_print_witness_badstacks(sb, &req->oldidx); 2778 2779 sbuf_finish(sb); 2780 error = SYSCTL_OUT(req, sbuf_data(sb), sbuf_len(sb) + 1); 2781 sbuf_delete(sb); 2782 2783 return (error); 2784 } 2785 2786 #ifdef DDB 2787 static int 2788 sbuf_db_printf_drain(void *arg __unused, const char *data, int len) 2789 { 2790 2791 return (db_printf("%.*s", len, data)); 2792 } 2793 2794 DB_SHOW_COMMAND(badstacks, db_witness_badstacks) 2795 { 2796 struct sbuf sb; 2797 char buffer[128]; 2798 size_t dummy; 2799 2800 sbuf_new(&sb, buffer, sizeof(buffer), SBUF_FIXEDLEN); 2801 sbuf_set_drain(&sb, sbuf_db_printf_drain, NULL); 2802 sbuf_print_witness_badstacks(&sb, &dummy); 2803 sbuf_finish(&sb); 2804 } 2805 #endif 2806 2807 static int 2808 sysctl_debug_witness_channel(SYSCTL_HANDLER_ARGS) 2809 { 2810 static const struct { 2811 enum witness_channel channel; 2812 const char *name; 2813 } channels[] = { 2814 { WITNESS_CONSOLE, "console" }, 2815 { WITNESS_LOG, "log" }, 2816 { WITNESS_NONE, "none" }, 2817 }; 2818 char buf[16]; 2819 u_int i; 2820 int error; 2821 2822 buf[0] = '\0'; 2823 for (i = 0; i < nitems(channels); i++) 2824 if (witness_channel == channels[i].channel) { 2825 snprintf(buf, sizeof(buf), "%s", channels[i].name); 2826 break; 2827 } 2828 2829 error = sysctl_handle_string(oidp, buf, sizeof(buf), req); 2830 if (error != 0 || req->newptr == NULL) 2831 return (error); 2832 2833 error = EINVAL; 2834 for (i = 0; i < nitems(channels); i++) 2835 if (strcmp(channels[i].name, buf) == 0) { 2836 witness_channel = channels[i].channel; 2837 error = 0; 2838 break; 2839 } 2840 return (error); 2841 } 2842 2843 static int 2844 sysctl_debug_witness_fullgraph(SYSCTL_HANDLER_ARGS) 2845 { 2846 struct witness *w; 2847 struct sbuf *sb; 2848 int error; 2849 2850 #ifdef __i386__ 2851 error = SYSCTL_OUT(req, w_notallowed, sizeof(w_notallowed)); 2852 return (error); 2853 #endif 2854 2855 if (witness_watch < 1) { 2856 error = SYSCTL_OUT(req, w_notrunning, sizeof(w_notrunning)); 2857 return (error); 2858 } 2859 if (witness_cold) { 2860 error = SYSCTL_OUT(req, w_stillcold, sizeof(w_stillcold)); 2861 return (error); 2862 } 2863 error = 0; 2864 2865 error = sysctl_wire_old_buffer(req, 0); 2866 if (error != 0) 2867 return (error); 2868 sb = sbuf_new_for_sysctl(NULL, NULL, FULLGRAPH_SBUF_SIZE, req); 2869 if (sb == NULL) 2870 return (ENOMEM); 2871 sbuf_printf(sb, "\n"); 2872 2873 mtx_lock_spin(&w_mtx); 2874 STAILQ_FOREACH(w, &w_all, w_list) 2875 w->w_displayed = 0; 2876 STAILQ_FOREACH(w, &w_all, w_list) 2877 witness_add_fullgraph(sb, w); 2878 mtx_unlock_spin(&w_mtx); 2879 2880 /* 2881 * Close the sbuf and return to userland. 2882 */ 2883 error = sbuf_finish(sb); 2884 sbuf_delete(sb); 2885 2886 return (error); 2887 } 2888 2889 static int 2890 sysctl_debug_witness_watch(SYSCTL_HANDLER_ARGS) 2891 { 2892 int error, value; 2893 2894 value = witness_watch; 2895 error = sysctl_handle_int(oidp, &value, 0, req); 2896 if (error != 0 || req->newptr == NULL) 2897 return (error); 2898 if (value > 1 || value < -1 || 2899 (witness_watch == -1 && value != witness_watch)) 2900 return (EINVAL); 2901 witness_watch = value; 2902 return (0); 2903 } 2904 2905 static void 2906 witness_add_fullgraph(struct sbuf *sb, struct witness *w) 2907 { 2908 int i; 2909 2910 if (w->w_displayed != 0 || (w->w_file == NULL && w->w_line == 0)) 2911 return; 2912 w->w_displayed = 1; 2913 2914 WITNESS_INDEX_ASSERT(w->w_index); 2915 for (i = 1; i <= w_max_used_index; i++) { 2916 if (w_rmatrix[w->w_index][i] & WITNESS_PARENT) { 2917 sbuf_printf(sb, "\"%s\",\"%s\"\n", w->w_name, 2918 w_data[i].w_name); 2919 witness_add_fullgraph(sb, &w_data[i]); 2920 } 2921 } 2922 } 2923 2924 /* 2925 * A simple hash function. Takes a key pointer and a key size. If size == 0, 2926 * interprets the key as a string and reads until the null 2927 * terminator. Otherwise, reads the first size bytes. Returns an unsigned 32-bit 2928 * hash value computed from the key. 2929 */ 2930 static uint32_t 2931 witness_hash_djb2(const uint8_t *key, uint32_t size) 2932 { 2933 unsigned int hash = 5381; 2934 int i; 2935 2936 /* hash = hash * 33 + key[i] */ 2937 if (size) 2938 for (i = 0; i < size; i++) 2939 hash = ((hash << 5) + hash) + (unsigned int)key[i]; 2940 else 2941 for (i = 0; key[i] != 0; i++) 2942 hash = ((hash << 5) + hash) + (unsigned int)key[i]; 2943 2944 return (hash); 2945 } 2946 2947 /* 2948 * Initializes the two witness hash tables. Called exactly once from 2949 * witness_initialize(). 2950 */ 2951 static void 2952 witness_init_hash_tables(void) 2953 { 2954 int i; 2955 2956 MPASS(witness_cold); 2957 2958 /* Initialize the hash tables. */ 2959 for (i = 0; i < WITNESS_HASH_SIZE; i++) 2960 w_hash.wh_array[i] = NULL; 2961 2962 w_hash.wh_size = WITNESS_HASH_SIZE; 2963 w_hash.wh_count = 0; 2964 2965 /* Initialize the lock order data hash. */ 2966 w_lofree = NULL; 2967 for (i = 0; i < WITNESS_LO_DATA_COUNT; i++) { 2968 memset(&w_lodata[i], 0, sizeof(w_lodata[i])); 2969 w_lodata[i].wlod_next = w_lofree; 2970 w_lofree = &w_lodata[i]; 2971 } 2972 w_lohash.wloh_size = WITNESS_LO_HASH_SIZE; 2973 w_lohash.wloh_count = 0; 2974 for (i = 0; i < WITNESS_LO_HASH_SIZE; i++) 2975 w_lohash.wloh_array[i] = NULL; 2976 } 2977 2978 static struct witness * 2979 witness_hash_get(const char *key) 2980 { 2981 struct witness *w; 2982 uint32_t hash; 2983 2984 MPASS(key != NULL); 2985 if (witness_cold == 0) 2986 mtx_assert(&w_mtx, MA_OWNED); 2987 hash = witness_hash_djb2(key, 0) % w_hash.wh_size; 2988 w = w_hash.wh_array[hash]; 2989 while (w != NULL) { 2990 if (strcmp(w->w_name, key) == 0) 2991 goto out; 2992 w = w->w_hash_next; 2993 } 2994 2995 out: 2996 return (w); 2997 } 2998 2999 static void 3000 witness_hash_put(struct witness *w) 3001 { 3002 uint32_t hash; 3003 3004 MPASS(w != NULL); 3005 MPASS(w->w_name != NULL); 3006 if (witness_cold == 0) 3007 mtx_assert(&w_mtx, MA_OWNED); 3008 KASSERT(witness_hash_get(w->w_name) == NULL, 3009 ("%s: trying to add a hash entry that already exists!", __func__)); 3010 KASSERT(w->w_hash_next == NULL, 3011 ("%s: w->w_hash_next != NULL", __func__)); 3012 3013 hash = witness_hash_djb2(w->w_name, 0) % w_hash.wh_size; 3014 w->w_hash_next = w_hash.wh_array[hash]; 3015 w_hash.wh_array[hash] = w; 3016 w_hash.wh_count++; 3017 } 3018 3019 static struct witness_lock_order_data * 3020 witness_lock_order_get(struct witness *parent, struct witness *child) 3021 { 3022 struct witness_lock_order_data *data = NULL; 3023 struct witness_lock_order_key key; 3024 unsigned int hash; 3025 3026 MPASS(parent != NULL && child != NULL); 3027 key.from = parent->w_index; 3028 key.to = child->w_index; 3029 WITNESS_INDEX_ASSERT(key.from); 3030 WITNESS_INDEX_ASSERT(key.to); 3031 if ((w_rmatrix[parent->w_index][child->w_index] 3032 & WITNESS_LOCK_ORDER_KNOWN) == 0) 3033 goto out; 3034 3035 hash = witness_hash_djb2((const char*)&key, 3036 sizeof(key)) % w_lohash.wloh_size; 3037 data = w_lohash.wloh_array[hash]; 3038 while (data != NULL) { 3039 if (witness_lock_order_key_equal(&data->wlod_key, &key)) 3040 break; 3041 data = data->wlod_next; 3042 } 3043 3044 out: 3045 return (data); 3046 } 3047 3048 /* 3049 * Verify that parent and child have a known relationship, are not the same, 3050 * and child is actually a child of parent. This is done without w_mtx 3051 * to avoid contention in the common case. 3052 */ 3053 static int 3054 witness_lock_order_check(struct witness *parent, struct witness *child) 3055 { 3056 3057 if (parent != child && 3058 w_rmatrix[parent->w_index][child->w_index] 3059 & WITNESS_LOCK_ORDER_KNOWN && 3060 isitmychild(parent, child)) 3061 return (1); 3062 3063 return (0); 3064 } 3065 3066 static int 3067 witness_lock_order_add(struct witness *parent, struct witness *child) 3068 { 3069 struct witness_lock_order_data *data = NULL; 3070 struct witness_lock_order_key key; 3071 unsigned int hash; 3072 3073 MPASS(parent != NULL && child != NULL); 3074 key.from = parent->w_index; 3075 key.to = child->w_index; 3076 WITNESS_INDEX_ASSERT(key.from); 3077 WITNESS_INDEX_ASSERT(key.to); 3078 if (w_rmatrix[parent->w_index][child->w_index] 3079 & WITNESS_LOCK_ORDER_KNOWN) 3080 return (1); 3081 3082 hash = witness_hash_djb2((const char*)&key, 3083 sizeof(key)) % w_lohash.wloh_size; 3084 w_rmatrix[parent->w_index][child->w_index] |= WITNESS_LOCK_ORDER_KNOWN; 3085 data = w_lofree; 3086 if (data == NULL) 3087 return (0); 3088 w_lofree = data->wlod_next; 3089 data->wlod_next = w_lohash.wloh_array[hash]; 3090 data->wlod_key = key; 3091 w_lohash.wloh_array[hash] = data; 3092 w_lohash.wloh_count++; 3093 stack_zero(&data->wlod_stack); 3094 stack_save(&data->wlod_stack); 3095 return (1); 3096 } 3097 3098 /* Call this whenever the structure of the witness graph changes. */ 3099 static void 3100 witness_increment_graph_generation(void) 3101 { 3102 3103 if (witness_cold == 0) 3104 mtx_assert(&w_mtx, MA_OWNED); 3105 w_generation++; 3106 } 3107 3108 static int 3109 witness_output_drain(void *arg __unused, const char *data, int len) 3110 { 3111 3112 witness_output("%.*s", len, data); 3113 return (len); 3114 } 3115 3116 static void 3117 witness_debugger(int cond, const char *msg) 3118 { 3119 char buf[32]; 3120 struct sbuf sb; 3121 struct stack st; 3122 3123 if (!cond) 3124 return; 3125 3126 if (witness_trace) { 3127 sbuf_new(&sb, buf, sizeof(buf), SBUF_FIXEDLEN); 3128 sbuf_set_drain(&sb, witness_output_drain, NULL); 3129 3130 stack_zero(&st); 3131 stack_save(&st); 3132 witness_output("stack backtrace:\n"); 3133 stack_sbuf_print_ddb(&sb, &st); 3134 3135 sbuf_finish(&sb); 3136 } 3137 3138 witness_enter_debugger(msg); 3139 } 3140 3141 static void 3142 witness_enter_debugger(const char *msg) 3143 { 3144 #ifdef KDB 3145 if (witness_kdb) 3146 kdb_enter(KDB_WHY_WITNESS, msg); 3147 #endif 3148 } 3149