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