1 /*- 2 * Copyright (c) 2008 Isilon Systems, Inc. 3 * Copyright (c) 2008 Ilya Maykov <ivmaykov@gmail.com> 4 * Copyright (c) 1998 Berkeley Software Design, Inc. 5 * All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 3. Berkeley Software Design Inc's name may not be used to endorse or 16 * promote products derived from this software without specific prior 17 * written permission. 18 * 19 * THIS SOFTWARE IS PROVIDED BY BERKELEY SOFTWARE DESIGN INC ``AS IS'' AND 20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22 * ARE DISCLAIMED. IN NO EVENT SHALL BERKELEY SOFTWARE DESIGN INC BE LIABLE 23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29 * SUCH DAMAGE. 30 * 31 * from BSDI $Id: mutex_witness.c,v 1.1.2.20 2000/04/27 03:10:27 cp Exp $ 32 * and BSDI $Id: synch_machdep.c,v 2.3.2.39 2000/04/27 03:10:25 cp Exp $ 33 */ 34 35 /* 36 * Implementation of the `witness' lock verifier. Originally implemented for 37 * mutexes in BSD/OS. Extended to handle generic lock objects and lock 38 * classes in FreeBSD. 39 */ 40 41 /* 42 * Main Entry: witness 43 * Pronunciation: 'wit-n&s 44 * Function: noun 45 * Etymology: Middle English witnesse, from Old English witnes knowledge, 46 * testimony, witness, from 2wit 47 * Date: before 12th century 48 * 1 : attestation of a fact or event : TESTIMONY 49 * 2 : one that gives evidence; specifically : one who testifies in 50 * a cause or before a judicial tribunal 51 * 3 : one asked to be present at a transaction so as to be able to 52 * testify to its having taken place 53 * 4 : one who has personal knowledge of something 54 * 5 a : something serving as evidence or proof : SIGN 55 * b : public affirmation by word or example of usually 56 * religious faith or conviction <the heroic witness to divine 57 * life -- Pilot> 58 * 6 capitalized : a member of the Jehovah's Witnesses 59 */ 60 61 /* 62 * Special rules concerning Giant and lock orders: 63 * 64 * 1) Giant must be acquired before any other mutexes. Stated another way, 65 * no other mutex may be held when Giant is acquired. 66 * 67 * 2) Giant must be released when blocking on a sleepable lock. 68 * 69 * This rule is less obvious, but is a result of Giant providing the same 70 * semantics as spl(). Basically, when a thread sleeps, it must release 71 * Giant. When a thread blocks on a sleepable lock, it sleeps. Hence rule 72 * 2). 73 * 74 * 3) Giant may be acquired before or after sleepable locks. 75 * 76 * This rule is also not quite as obvious. Giant may be acquired after 77 * a sleepable lock because it is a non-sleepable lock and non-sleepable 78 * locks may always be acquired while holding a sleepable lock. The second 79 * case, Giant before a sleepable lock, follows from rule 2) above. Suppose 80 * you have two threads T1 and T2 and a sleepable lock X. Suppose that T1 81 * acquires X and blocks on Giant. Then suppose that T2 acquires Giant and 82 * blocks on X. When T2 blocks on X, T2 will release Giant allowing T1 to 83 * execute. Thus, acquiring Giant both before and after a sleepable lock 84 * will not result in a lock order reversal. 85 */ 86 87 #include <sys/cdefs.h> 88 __FBSDID("$FreeBSD$"); 89 90 #include "opt_ddb.h" 91 #include "opt_hwpmc_hooks.h" 92 #include "opt_stack.h" 93 #include "opt_witness.h" 94 95 #include <sys/param.h> 96 #include <sys/bus.h> 97 #include <sys/kdb.h> 98 #include <sys/kernel.h> 99 #include <sys/ktr.h> 100 #include <sys/lock.h> 101 #include <sys/malloc.h> 102 #include <sys/mutex.h> 103 #include <sys/priv.h> 104 #include <sys/proc.h> 105 #include <sys/sbuf.h> 106 #include <sys/sched.h> 107 #include <sys/stack.h> 108 #include <sys/sysctl.h> 109 #include <sys/systm.h> 110 111 #ifdef DDB 112 #include <ddb/ddb.h> 113 #endif 114 115 #include <machine/stdarg.h> 116 117 #if !defined(DDB) && !defined(STACK) 118 #error "DDB or STACK options are required for WITNESS" 119 #endif 120 121 /* Note that these traces do not work with KTR_ALQ. */ 122 #if 0 123 #define KTR_WITNESS KTR_SUBSYS 124 #else 125 #define KTR_WITNESS 0 126 #endif 127 128 #define LI_RECURSEMASK 0x0000ffff /* Recursion depth of lock instance. */ 129 #define LI_EXCLUSIVE 0x00010000 /* Exclusive lock instance. */ 130 #define LI_NORELEASE 0x00020000 /* Lock not allowed to be released. */ 131 132 /* Define this to check for blessed mutexes */ 133 #undef BLESSING 134 135 #define WITNESS_COUNT 1024 136 #define WITNESS_CHILDCOUNT (WITNESS_COUNT * 4) 137 #define WITNESS_HASH_SIZE 251 /* Prime, gives load factor < 2 */ 138 #define WITNESS_PENDLIST 512 139 140 /* Allocate 256 KB of stack data space */ 141 #define WITNESS_LO_DATA_COUNT 2048 142 143 /* Prime, gives load factor of ~2 at full load */ 144 #define WITNESS_LO_HASH_SIZE 1021 145 146 /* 147 * XXX: This is somewhat bogus, as we assume here that at most 2048 threads 148 * will hold LOCK_NCHILDREN locks. We handle failure ok, and we should 149 * probably be safe for the most part, but it's still a SWAG. 150 */ 151 #define LOCK_NCHILDREN 5 152 #define LOCK_CHILDCOUNT 2048 153 154 #define MAX_W_NAME 64 155 156 #define BADSTACK_SBUF_SIZE (256 * WITNESS_COUNT) 157 #define CYCLEGRAPH_SBUF_SIZE 8192 158 #define FULLGRAPH_SBUF_SIZE 32768 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 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 #ifdef BLESSING 280 struct witness_blessed { 281 const char *b_lock1; 282 const char *b_lock2; 283 }; 284 #endif 285 286 struct witness_pendhelp { 287 const char *wh_type; 288 struct lock_object *wh_lock; 289 }; 290 291 struct witness_order_list_entry { 292 const char *w_name; 293 struct lock_class *w_class; 294 }; 295 296 /* 297 * Returns 0 if one of the locks is a spin lock and the other is not. 298 * Returns 1 otherwise. 299 */ 300 static __inline int 301 witness_lock_type_equal(struct witness *w1, struct witness *w2) 302 { 303 304 return ((w1->w_class->lc_flags & (LC_SLEEPLOCK | LC_SPINLOCK)) == 305 (w2->w_class->lc_flags & (LC_SLEEPLOCK | LC_SPINLOCK))); 306 } 307 308 static __inline int 309 witness_lock_order_key_empty(const struct witness_lock_order_key *key) 310 { 311 312 return (key->from == 0 && key->to == 0); 313 } 314 315 static __inline int 316 witness_lock_order_key_equal(const struct witness_lock_order_key *a, 317 const struct witness_lock_order_key *b) 318 { 319 320 return (a->from == b->from && a->to == b->to); 321 } 322 323 static int _isitmyx(struct witness *w1, struct witness *w2, int rmask, 324 const char *fname); 325 #ifdef KDB 326 static void _witness_debugger(int cond, const char *msg); 327 #endif 328 static void adopt(struct witness *parent, struct witness *child); 329 #ifdef BLESSING 330 static int blessed(struct witness *, struct witness *); 331 #endif 332 static void depart(struct witness *w); 333 static struct witness *enroll(const char *description, 334 struct lock_class *lock_class); 335 static struct lock_instance *find_instance(struct lock_list_entry *list, 336 struct lock_object *lock); 337 static int isitmychild(struct witness *parent, struct witness *child); 338 static int isitmydescendant(struct witness *parent, struct witness *child); 339 static void itismychild(struct witness *parent, struct witness *child); 340 static int sysctl_debug_witness_badstacks(SYSCTL_HANDLER_ARGS); 341 static int sysctl_debug_witness_watch(SYSCTL_HANDLER_ARGS); 342 static int sysctl_debug_witness_fullgraph(SYSCTL_HANDLER_ARGS); 343 static void witness_add_fullgraph(struct sbuf *sb, struct witness *parent); 344 #ifdef DDB 345 static void witness_ddb_compute_levels(void); 346 static void witness_ddb_display(void(*)(const char *fmt, ...)); 347 static void witness_ddb_display_descendants(void(*)(const char *fmt, ...), 348 struct witness *, int indent); 349 static void witness_ddb_display_list(void(*prnt)(const char *fmt, ...), 350 struct witness_list *list); 351 static void witness_ddb_level_descendants(struct witness *parent, int l); 352 static void witness_ddb_list(struct thread *td); 353 #endif 354 static void witness_free(struct witness *m); 355 static struct witness *witness_get(void); 356 static uint32_t witness_hash_djb2(const uint8_t *key, uint32_t size); 357 static struct witness *witness_hash_get(const char *key); 358 static void witness_hash_put(struct witness *w); 359 static void witness_init_hash_tables(void); 360 static void witness_increment_graph_generation(void); 361 static void witness_lock_list_free(struct lock_list_entry *lle); 362 static struct lock_list_entry *witness_lock_list_get(void); 363 static int witness_lock_order_add(struct witness *parent, 364 struct witness *child); 365 static int witness_lock_order_check(struct witness *parent, 366 struct witness *child); 367 static struct witness_lock_order_data *witness_lock_order_get( 368 struct witness *parent, 369 struct witness *child); 370 static void witness_list_lock(struct lock_instance *instance); 371 static void witness_setflag(struct lock_object *lock, int flag, int set); 372 373 #ifdef KDB 374 #define witness_debugger(c) _witness_debugger(c, __func__) 375 #else 376 #define witness_debugger(c) 377 #endif 378 379 SYSCTL_NODE(_debug, OID_AUTO, witness, CTLFLAG_RW, NULL, "Witness Locking"); 380 381 /* 382 * If set to 0, lock order checking is disabled. If set to -1, 383 * witness is completely disabled. Otherwise witness performs full 384 * lock order checking for all locks. At runtime, lock order checking 385 * may be toggled. However, witness cannot be reenabled once it is 386 * completely disabled. 387 */ 388 static int witness_watch = 1; 389 TUNABLE_INT("debug.witness.watch", &witness_watch); 390 SYSCTL_PROC(_debug_witness, OID_AUTO, watch, CTLFLAG_RW | CTLTYPE_INT, NULL, 0, 391 sysctl_debug_witness_watch, "I", "witness is watching lock operations"); 392 393 #ifdef KDB 394 /* 395 * When KDB is enabled and witness_kdb is 1, it will cause the system 396 * to drop into kdebug() when: 397 * - a lock hierarchy violation occurs 398 * - locks are held when going to sleep. 399 */ 400 #ifdef WITNESS_KDB 401 int witness_kdb = 1; 402 #else 403 int witness_kdb = 0; 404 #endif 405 TUNABLE_INT("debug.witness.kdb", &witness_kdb); 406 SYSCTL_INT(_debug_witness, OID_AUTO, kdb, CTLFLAG_RW, &witness_kdb, 0, ""); 407 408 /* 409 * When KDB is enabled and witness_trace is 1, it will cause the system 410 * to print a stack trace: 411 * - a lock hierarchy violation occurs 412 * - locks are held when going to sleep. 413 */ 414 int witness_trace = 1; 415 TUNABLE_INT("debug.witness.trace", &witness_trace); 416 SYSCTL_INT(_debug_witness, OID_AUTO, trace, CTLFLAG_RW, &witness_trace, 0, ""); 417 #endif /* KDB */ 418 419 #ifdef WITNESS_SKIPSPIN 420 int witness_skipspin = 1; 421 #else 422 int witness_skipspin = 0; 423 #endif 424 TUNABLE_INT("debug.witness.skipspin", &witness_skipspin); 425 SYSCTL_INT(_debug_witness, OID_AUTO, skipspin, CTLFLAG_RDTUN, &witness_skipspin, 426 0, ""); 427 428 /* 429 * Call this to print out the relations between locks. 430 */ 431 SYSCTL_PROC(_debug_witness, OID_AUTO, fullgraph, CTLTYPE_STRING | CTLFLAG_RD, 432 NULL, 0, sysctl_debug_witness_fullgraph, "A", "Show locks relation graphs"); 433 434 /* 435 * Call this to print out the witness faulty stacks. 436 */ 437 SYSCTL_PROC(_debug_witness, OID_AUTO, badstacks, CTLTYPE_STRING | CTLFLAG_RD, 438 NULL, 0, sysctl_debug_witness_badstacks, "A", "Show bad witness stacks"); 439 440 static struct mtx w_mtx; 441 442 /* w_list */ 443 static struct witness_list w_free = STAILQ_HEAD_INITIALIZER(w_free); 444 static struct witness_list w_all = STAILQ_HEAD_INITIALIZER(w_all); 445 446 /* w_typelist */ 447 static struct witness_list w_spin = STAILQ_HEAD_INITIALIZER(w_spin); 448 static struct witness_list w_sleep = STAILQ_HEAD_INITIALIZER(w_sleep); 449 450 /* lock list */ 451 static struct lock_list_entry *w_lock_list_free = NULL; 452 static struct witness_pendhelp pending_locks[WITNESS_PENDLIST]; 453 static u_int pending_cnt; 454 455 static int w_free_cnt, w_spin_cnt, w_sleep_cnt; 456 SYSCTL_INT(_debug_witness, OID_AUTO, free_cnt, CTLFLAG_RD, &w_free_cnt, 0, ""); 457 SYSCTL_INT(_debug_witness, OID_AUTO, spin_cnt, CTLFLAG_RD, &w_spin_cnt, 0, ""); 458 SYSCTL_INT(_debug_witness, OID_AUTO, sleep_cnt, CTLFLAG_RD, &w_sleep_cnt, 0, 459 ""); 460 461 static struct witness *w_data; 462 static uint8_t w_rmatrix[WITNESS_COUNT+1][WITNESS_COUNT+1]; 463 static struct lock_list_entry w_locklistdata[LOCK_CHILDCOUNT]; 464 static struct witness_hash w_hash; /* The witness hash table. */ 465 466 /* The lock order data hash */ 467 static struct witness_lock_order_data w_lodata[WITNESS_LO_DATA_COUNT]; 468 static struct witness_lock_order_data *w_lofree = NULL; 469 static struct witness_lock_order_hash w_lohash; 470 static int w_max_used_index = 0; 471 static unsigned int w_generation = 0; 472 static const char *w_notrunning = "Witness not running\n"; 473 static const char *w_stillcold = "Witness is still cold\n"; 474 475 476 static struct witness_order_list_entry order_lists[] = { 477 /* 478 * sx locks 479 */ 480 { "proctree", &lock_class_sx }, 481 { "allproc", &lock_class_sx }, 482 { "allprison", &lock_class_sx }, 483 { NULL, NULL }, 484 /* 485 * Various mutexes 486 */ 487 { "Giant", &lock_class_mtx_sleep }, 488 { "pipe mutex", &lock_class_mtx_sleep }, 489 { "sigio lock", &lock_class_mtx_sleep }, 490 { "process group", &lock_class_mtx_sleep }, 491 { "process lock", &lock_class_mtx_sleep }, 492 { "session", &lock_class_mtx_sleep }, 493 { "uidinfo hash", &lock_class_rw }, 494 #ifdef HWPMC_HOOKS 495 { "pmc-sleep", &lock_class_mtx_sleep }, 496 #endif 497 { NULL, NULL }, 498 /* 499 * Sockets 500 */ 501 { "accept", &lock_class_mtx_sleep }, 502 { "so_snd", &lock_class_mtx_sleep }, 503 { "so_rcv", &lock_class_mtx_sleep }, 504 { "sellck", &lock_class_mtx_sleep }, 505 { NULL, NULL }, 506 /* 507 * Routing 508 */ 509 { "so_rcv", &lock_class_mtx_sleep }, 510 { "radix node head", &lock_class_rw }, 511 { "rtentry", &lock_class_mtx_sleep }, 512 { "ifaddr", &lock_class_mtx_sleep }, 513 { NULL, NULL }, 514 /* 515 * Multicast - protocol locks before interface locks, after UDP locks. 516 */ 517 { "udpinp", &lock_class_rw }, 518 { "in_multi_mtx", &lock_class_mtx_sleep }, 519 { "igmp_mtx", &lock_class_mtx_sleep }, 520 { "if_addr_mtx", &lock_class_mtx_sleep }, 521 { NULL, NULL }, 522 /* 523 * UNIX Domain Sockets 524 */ 525 { "unp", &lock_class_mtx_sleep }, 526 { "so_snd", &lock_class_mtx_sleep }, 527 { NULL, NULL }, 528 /* 529 * UDP/IP 530 */ 531 { "udp", &lock_class_rw }, 532 { "udpinp", &lock_class_rw }, 533 { "so_snd", &lock_class_mtx_sleep }, 534 { NULL, NULL }, 535 /* 536 * TCP/IP 537 */ 538 { "tcp", &lock_class_rw }, 539 { "tcpinp", &lock_class_rw }, 540 { "so_snd", &lock_class_mtx_sleep }, 541 { NULL, NULL }, 542 /* 543 * SLIP 544 */ 545 { "slip_mtx", &lock_class_mtx_sleep }, 546 { "slip sc_mtx", &lock_class_mtx_sleep }, 547 { NULL, NULL }, 548 /* 549 * netatalk 550 */ 551 { "ddp_list_mtx", &lock_class_mtx_sleep }, 552 { "ddp_mtx", &lock_class_mtx_sleep }, 553 { NULL, NULL }, 554 /* 555 * BPF 556 */ 557 { "bpf global lock", &lock_class_mtx_sleep }, 558 { "bpf interface lock", &lock_class_mtx_sleep }, 559 { "bpf cdev lock", &lock_class_mtx_sleep }, 560 { NULL, NULL }, 561 /* 562 * NFS server 563 */ 564 { "nfsd_mtx", &lock_class_mtx_sleep }, 565 { "so_snd", &lock_class_mtx_sleep }, 566 { NULL, NULL }, 567 568 /* 569 * IEEE 802.11 570 */ 571 { "802.11 com lock", &lock_class_mtx_sleep}, 572 { NULL, NULL }, 573 /* 574 * Network drivers 575 */ 576 { "network driver", &lock_class_mtx_sleep}, 577 { NULL, NULL }, 578 579 /* 580 * Netgraph 581 */ 582 { "ng_node", &lock_class_mtx_sleep }, 583 { "ng_worklist", &lock_class_mtx_sleep }, 584 { NULL, NULL }, 585 /* 586 * CDEV 587 */ 588 { "system map", &lock_class_mtx_sleep }, 589 { "vm page queue mutex", &lock_class_mtx_sleep }, 590 { "vnode interlock", &lock_class_mtx_sleep }, 591 { "cdev", &lock_class_mtx_sleep }, 592 { NULL, NULL }, 593 /* 594 * kqueue/VFS interaction 595 */ 596 { "kqueue", &lock_class_mtx_sleep }, 597 { "struct mount mtx", &lock_class_mtx_sleep }, 598 { "vnode interlock", &lock_class_mtx_sleep }, 599 { NULL, NULL }, 600 /* 601 * spin locks 602 */ 603 #ifdef SMP 604 { "ap boot", &lock_class_mtx_spin }, 605 #endif 606 { "rm.mutex_mtx", &lock_class_mtx_spin }, 607 { "sio", &lock_class_mtx_spin }, 608 { "scrlock", &lock_class_mtx_spin }, 609 #ifdef __i386__ 610 { "cy", &lock_class_mtx_spin }, 611 #endif 612 #ifdef __sparc64__ 613 { "pcib_mtx", &lock_class_mtx_spin }, 614 { "rtc_mtx", &lock_class_mtx_spin }, 615 #endif 616 { "scc_hwmtx", &lock_class_mtx_spin }, 617 { "uart_hwmtx", &lock_class_mtx_spin }, 618 { "fast_taskqueue", &lock_class_mtx_spin }, 619 { "intr table", &lock_class_mtx_spin }, 620 #ifdef HWPMC_HOOKS 621 { "pmc-per-proc", &lock_class_mtx_spin }, 622 #endif 623 { "process slock", &lock_class_mtx_spin }, 624 { "sleepq chain", &lock_class_mtx_spin }, 625 { "umtx lock", &lock_class_mtx_spin }, 626 { "rm_spinlock", &lock_class_mtx_spin }, 627 { "turnstile chain", &lock_class_mtx_spin }, 628 { "turnstile lock", &lock_class_mtx_spin }, 629 { "sched lock", &lock_class_mtx_spin }, 630 { "td_contested", &lock_class_mtx_spin }, 631 { "callout", &lock_class_mtx_spin }, 632 { "entropy harvest mutex", &lock_class_mtx_spin }, 633 { "syscons video lock", &lock_class_mtx_spin }, 634 { "time lock", &lock_class_mtx_spin }, 635 #ifdef SMP 636 { "smp rendezvous", &lock_class_mtx_spin }, 637 #endif 638 #ifdef __powerpc__ 639 { "tlb0", &lock_class_mtx_spin }, 640 #endif 641 /* 642 * leaf locks 643 */ 644 { "intrcnt", &lock_class_mtx_spin }, 645 { "icu", &lock_class_mtx_spin }, 646 #if defined(SMP) && defined(__sparc64__) 647 { "ipi", &lock_class_mtx_spin }, 648 #endif 649 #ifdef __i386__ 650 { "allpmaps", &lock_class_mtx_spin }, 651 { "descriptor tables", &lock_class_mtx_spin }, 652 #endif 653 { "clk", &lock_class_mtx_spin }, 654 { "cpuset", &lock_class_mtx_spin }, 655 { "mprof lock", &lock_class_mtx_spin }, 656 { "zombie lock", &lock_class_mtx_spin }, 657 { "ALD Queue", &lock_class_mtx_spin }, 658 #ifdef __ia64__ 659 { "MCA spin lock", &lock_class_mtx_spin }, 660 #endif 661 #if defined(__i386__) || defined(__amd64__) 662 { "pcicfg", &lock_class_mtx_spin }, 663 { "NDIS thread lock", &lock_class_mtx_spin }, 664 #endif 665 { "tw_osl_io_lock", &lock_class_mtx_spin }, 666 { "tw_osl_q_lock", &lock_class_mtx_spin }, 667 { "tw_cl_io_lock", &lock_class_mtx_spin }, 668 { "tw_cl_intr_lock", &lock_class_mtx_spin }, 669 { "tw_cl_gen_lock", &lock_class_mtx_spin }, 670 #ifdef HWPMC_HOOKS 671 { "pmc-leaf", &lock_class_mtx_spin }, 672 #endif 673 { "blocked lock", &lock_class_mtx_spin }, 674 { NULL, NULL }, 675 { NULL, NULL } 676 }; 677 678 #ifdef BLESSING 679 /* 680 * Pairs of locks which have been blessed 681 * Don't complain about order problems with blessed locks 682 */ 683 static struct witness_blessed blessed_list[] = { 684 }; 685 static int blessed_count = 686 sizeof(blessed_list) / sizeof(struct witness_blessed); 687 #endif 688 689 /* 690 * This global is set to 0 once it becomes safe to use the witness code. 691 */ 692 static int witness_cold = 1; 693 694 /* 695 * This global is set to 1 once the static lock orders have been enrolled 696 * so that a warning can be issued for any spin locks enrolled later. 697 */ 698 static int witness_spin_warn = 0; 699 700 /* 701 * The WITNESS-enabled diagnostic code. Note that the witness code does 702 * assume that the early boot is single-threaded at least until after this 703 * routine is completed. 704 */ 705 static void 706 witness_initialize(void *dummy __unused) 707 { 708 struct lock_object *lock; 709 struct witness_order_list_entry *order; 710 struct witness *w, *w1; 711 int i; 712 713 w_data = malloc(sizeof (struct witness) * WITNESS_COUNT, M_WITNESS, 714 M_NOWAIT | M_ZERO); 715 716 /* 717 * We have to release Giant before initializing its witness 718 * structure so that WITNESS doesn't get confused. 719 */ 720 mtx_unlock(&Giant); 721 mtx_assert(&Giant, MA_NOTOWNED); 722 723 CTR1(KTR_WITNESS, "%s: initializing witness", __func__); 724 mtx_init(&w_mtx, "witness lock", NULL, MTX_SPIN | MTX_QUIET | 725 MTX_NOWITNESS | MTX_NOPROFILE); 726 for (i = WITNESS_COUNT - 1; i >= 0; i--) { 727 w = &w_data[i]; 728 memset(w, 0, sizeof(*w)); 729 w_data[i].w_index = i; /* Witness index never changes. */ 730 witness_free(w); 731 } 732 KASSERT(STAILQ_FIRST(&w_free)->w_index == 0, 733 ("%s: Invalid list of free witness objects", __func__)); 734 735 /* Witness with index 0 is not used to aid in debugging. */ 736 STAILQ_REMOVE_HEAD(&w_free, w_list); 737 w_free_cnt--; 738 739 memset(w_rmatrix, 0, 740 (sizeof(**w_rmatrix) * (WITNESS_COUNT+1) * (WITNESS_COUNT+1))); 741 742 for (i = 0; i < LOCK_CHILDCOUNT; i++) 743 witness_lock_list_free(&w_locklistdata[i]); 744 witness_init_hash_tables(); 745 746 /* First add in all the specified order lists. */ 747 for (order = order_lists; order->w_name != NULL; order++) { 748 w = enroll(order->w_name, order->w_class); 749 if (w == NULL) 750 continue; 751 w->w_file = "order list"; 752 for (order++; order->w_name != NULL; order++) { 753 w1 = enroll(order->w_name, order->w_class); 754 if (w1 == NULL) 755 continue; 756 w1->w_file = "order list"; 757 itismychild(w, w1); 758 w = w1; 759 } 760 } 761 witness_spin_warn = 1; 762 763 /* Iterate through all locks and add them to witness. */ 764 for (i = 0; pending_locks[i].wh_lock != NULL; i++) { 765 lock = pending_locks[i].wh_lock; 766 KASSERT(lock->lo_flags & LO_WITNESS, 767 ("%s: lock %s is on pending list but not LO_WITNESS", 768 __func__, lock->lo_name)); 769 lock->lo_witness = enroll(pending_locks[i].wh_type, 770 LOCK_CLASS(lock)); 771 } 772 773 /* Mark the witness code as being ready for use. */ 774 witness_cold = 0; 775 776 mtx_lock(&Giant); 777 } 778 SYSINIT(witness_init, SI_SUB_WITNESS, SI_ORDER_FIRST, witness_initialize, 779 NULL); 780 781 void 782 witness_init(struct lock_object *lock, const char *type) 783 { 784 struct lock_class *class; 785 786 /* Various sanity checks. */ 787 class = LOCK_CLASS(lock); 788 if ((lock->lo_flags & LO_RECURSABLE) != 0 && 789 (class->lc_flags & LC_RECURSABLE) == 0) 790 panic("%s: lock (%s) %s can not be recursable", __func__, 791 class->lc_name, lock->lo_name); 792 if ((lock->lo_flags & LO_SLEEPABLE) != 0 && 793 (class->lc_flags & LC_SLEEPABLE) == 0) 794 panic("%s: lock (%s) %s can not be sleepable", __func__, 795 class->lc_name, lock->lo_name); 796 if ((lock->lo_flags & LO_UPGRADABLE) != 0 && 797 (class->lc_flags & LC_UPGRADABLE) == 0) 798 panic("%s: lock (%s) %s can not be upgradable", __func__, 799 class->lc_name, lock->lo_name); 800 801 /* 802 * If we shouldn't watch this lock, then just clear lo_witness. 803 * Otherwise, if witness_cold is set, then it is too early to 804 * enroll this lock, so defer it to witness_initialize() by adding 805 * it to the pending_locks list. If it is not too early, then enroll 806 * the lock now. 807 */ 808 if (witness_watch < 1 || panicstr != NULL || 809 (lock->lo_flags & LO_WITNESS) == 0) 810 lock->lo_witness = NULL; 811 else if (witness_cold) { 812 pending_locks[pending_cnt].wh_lock = lock; 813 pending_locks[pending_cnt++].wh_type = type; 814 if (pending_cnt > WITNESS_PENDLIST) 815 panic("%s: pending locks list is too small, bump it\n", 816 __func__); 817 } else 818 lock->lo_witness = enroll(type, class); 819 } 820 821 void 822 witness_destroy(struct lock_object *lock) 823 { 824 struct lock_class *class; 825 struct witness *w; 826 827 class = LOCK_CLASS(lock); 828 829 if (witness_cold) 830 panic("lock (%s) %s destroyed while witness_cold", 831 class->lc_name, lock->lo_name); 832 833 /* XXX: need to verify that no one holds the lock */ 834 if ((lock->lo_flags & LO_WITNESS) == 0 || lock->lo_witness == NULL) 835 return; 836 w = lock->lo_witness; 837 838 mtx_lock_spin(&w_mtx); 839 MPASS(w->w_refcount > 0); 840 w->w_refcount--; 841 842 if (w->w_refcount == 0) 843 depart(w); 844 mtx_unlock_spin(&w_mtx); 845 } 846 847 #ifdef DDB 848 static void 849 witness_ddb_compute_levels(void) 850 { 851 struct witness *w; 852 853 /* 854 * First clear all levels. 855 */ 856 STAILQ_FOREACH(w, &w_all, w_list) 857 w->w_ddb_level = -1; 858 859 /* 860 * Look for locks with no parents and level all their descendants. 861 */ 862 STAILQ_FOREACH(w, &w_all, w_list) { 863 864 /* If the witness has ancestors (is not a root), skip it. */ 865 if (w->w_num_ancestors > 0) 866 continue; 867 witness_ddb_level_descendants(w, 0); 868 } 869 } 870 871 static void 872 witness_ddb_level_descendants(struct witness *w, int l) 873 { 874 int i; 875 876 if (w->w_ddb_level >= l) 877 return; 878 879 w->w_ddb_level = l; 880 l++; 881 882 for (i = 1; i <= w_max_used_index; i++) { 883 if (w_rmatrix[w->w_index][i] & WITNESS_PARENT) 884 witness_ddb_level_descendants(&w_data[i], l); 885 } 886 } 887 888 static void 889 witness_ddb_display_descendants(void(*prnt)(const char *fmt, ...), 890 struct witness *w, int indent) 891 { 892 int i; 893 894 for (i = 0; i < indent; i++) 895 prnt(" "); 896 prnt("%s (type: %s, depth: %d, active refs: %d)", 897 w->w_name, w->w_class->lc_name, 898 w->w_ddb_level, w->w_refcount); 899 if (w->w_displayed) { 900 prnt(" -- (already displayed)\n"); 901 return; 902 } 903 w->w_displayed = 1; 904 if (w->w_file != NULL && w->w_line != 0) 905 prnt(" -- last acquired @ %s:%d\n", w->w_file, 906 w->w_line); 907 else 908 prnt(" -- never acquired\n"); 909 indent++; 910 WITNESS_INDEX_ASSERT(w->w_index); 911 for (i = 1; i <= w_max_used_index; i++) { 912 if (w_rmatrix[w->w_index][i] & WITNESS_PARENT) 913 witness_ddb_display_descendants(prnt, &w_data[i], 914 indent); 915 } 916 } 917 918 static void 919 witness_ddb_display_list(void(*prnt)(const char *fmt, ...), 920 struct witness_list *list) 921 { 922 struct witness *w; 923 924 STAILQ_FOREACH(w, list, w_typelist) { 925 if (w->w_file == NULL || w->w_ddb_level > 0) 926 continue; 927 928 /* This lock has no anscestors - display its descendants. */ 929 witness_ddb_display_descendants(prnt, w, 0); 930 } 931 } 932 933 static void 934 witness_ddb_display(void(*prnt)(const char *fmt, ...)) 935 { 936 struct witness *w; 937 938 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); 939 witness_ddb_compute_levels(); 940 941 /* Clear all the displayed flags. */ 942 STAILQ_FOREACH(w, &w_all, w_list) 943 w->w_displayed = 0; 944 945 /* 946 * First, handle sleep locks which have been acquired at least 947 * once. 948 */ 949 prnt("Sleep locks:\n"); 950 witness_ddb_display_list(prnt, &w_sleep); 951 952 /* 953 * Now do spin locks which have been acquired at least once. 954 */ 955 prnt("\nSpin locks:\n"); 956 witness_ddb_display_list(prnt, &w_spin); 957 958 /* 959 * Finally, any locks which have not been acquired yet. 960 */ 961 prnt("\nLocks which were never acquired:\n"); 962 STAILQ_FOREACH(w, &w_all, w_list) { 963 if (w->w_file != NULL || w->w_refcount == 0) 964 continue; 965 prnt("%s (type: %s, depth: %d)\n", w->w_name, 966 w->w_class->lc_name, w->w_ddb_level); 967 } 968 } 969 #endif /* DDB */ 970 971 /* Trim useless garbage from filenames. */ 972 static const char * 973 fixup_filename(const char *file) 974 { 975 976 if (file == NULL) 977 return (NULL); 978 while (strncmp(file, "../", 3) == 0) 979 file += 3; 980 return (file); 981 } 982 983 int 984 witness_defineorder(struct lock_object *lock1, struct lock_object *lock2) 985 { 986 987 if (witness_watch == -1 || panicstr != NULL) 988 return (0); 989 990 /* Require locks that witness knows about. */ 991 if (lock1 == NULL || lock1->lo_witness == NULL || lock2 == NULL || 992 lock2->lo_witness == NULL) 993 return (EINVAL); 994 995 mtx_assert(&w_mtx, MA_NOTOWNED); 996 mtx_lock_spin(&w_mtx); 997 998 /* 999 * If we already have either an explicit or implied lock order that 1000 * is the other way around, then return an error. 1001 */ 1002 if (witness_watch && 1003 isitmydescendant(lock2->lo_witness, lock1->lo_witness)) { 1004 mtx_unlock_spin(&w_mtx); 1005 return (EDOOFUS); 1006 } 1007 1008 /* Try to add the new order. */ 1009 CTR3(KTR_WITNESS, "%s: adding %s as a child of %s", __func__, 1010 lock2->lo_witness->w_name, lock1->lo_witness->w_name); 1011 itismychild(lock1->lo_witness, lock2->lo_witness); 1012 mtx_unlock_spin(&w_mtx); 1013 return (0); 1014 } 1015 1016 void 1017 witness_checkorder(struct lock_object *lock, int flags, const char *file, 1018 int line, struct lock_object *interlock) 1019 { 1020 struct lock_list_entry *lock_list, *lle; 1021 struct lock_instance *lock1, *lock2, *plock; 1022 struct lock_class *class; 1023 struct witness *w, *w1; 1024 struct thread *td; 1025 int i, j; 1026 1027 if (witness_cold || witness_watch < 1 || lock->lo_witness == NULL || 1028 panicstr != NULL) 1029 return; 1030 1031 w = lock->lo_witness; 1032 class = LOCK_CLASS(lock); 1033 td = curthread; 1034 file = fixup_filename(file); 1035 1036 if (class->lc_flags & LC_SLEEPLOCK) { 1037 1038 /* 1039 * Since spin locks include a critical section, this check 1040 * implicitly enforces a lock order of all sleep locks before 1041 * all spin locks. 1042 */ 1043 if (td->td_critnest != 0 && !kdb_active) 1044 panic("blockable sleep lock (%s) %s @ %s:%d", 1045 class->lc_name, lock->lo_name, file, line); 1046 1047 /* 1048 * If this is the first lock acquired then just return as 1049 * no order checking is needed. 1050 */ 1051 lock_list = td->td_sleeplocks; 1052 if (lock_list == NULL || lock_list->ll_count == 0) 1053 return; 1054 } else { 1055 1056 /* 1057 * If this is the first lock, just return as no order 1058 * checking is needed. Avoid problems with thread 1059 * migration pinning the thread while checking if 1060 * spinlocks are held. If at least one spinlock is held 1061 * the thread is in a safe path and it is allowed to 1062 * unpin it. 1063 */ 1064 sched_pin(); 1065 lock_list = PCPU_GET(spinlocks); 1066 if (lock_list == NULL || lock_list->ll_count == 0) { 1067 sched_unpin(); 1068 return; 1069 } 1070 sched_unpin(); 1071 } 1072 1073 /* 1074 * Check to see if we are recursing on a lock we already own. If 1075 * so, make sure that we don't mismatch exclusive and shared lock 1076 * acquires. 1077 */ 1078 lock1 = find_instance(lock_list, lock); 1079 if (lock1 != NULL) { 1080 if ((lock1->li_flags & LI_EXCLUSIVE) != 0 && 1081 (flags & LOP_EXCLUSIVE) == 0) { 1082 printf("shared lock of (%s) %s @ %s:%d\n", 1083 class->lc_name, lock->lo_name, file, line); 1084 printf("while exclusively locked from %s:%d\n", 1085 lock1->li_file, lock1->li_line); 1086 panic("share->excl"); 1087 } 1088 if ((lock1->li_flags & LI_EXCLUSIVE) == 0 && 1089 (flags & LOP_EXCLUSIVE) != 0) { 1090 printf("exclusive lock of (%s) %s @ %s:%d\n", 1091 class->lc_name, lock->lo_name, file, line); 1092 printf("while share locked from %s:%d\n", 1093 lock1->li_file, lock1->li_line); 1094 panic("excl->share"); 1095 } 1096 return; 1097 } 1098 1099 /* 1100 * Find the previously acquired lock, but ignore interlocks. 1101 */ 1102 plock = &lock_list->ll_children[lock_list->ll_count - 1]; 1103 if (interlock != NULL && plock->li_lock == interlock) { 1104 if (lock_list->ll_count > 1) 1105 plock = 1106 &lock_list->ll_children[lock_list->ll_count - 2]; 1107 else { 1108 lle = lock_list->ll_next; 1109 1110 /* 1111 * The interlock is the only lock we hold, so 1112 * simply return. 1113 */ 1114 if (lle == NULL) 1115 return; 1116 plock = &lle->ll_children[lle->ll_count - 1]; 1117 } 1118 } 1119 1120 /* 1121 * Try to perform most checks without a lock. If this succeeds we 1122 * can skip acquiring the lock and return success. 1123 */ 1124 w1 = plock->li_lock->lo_witness; 1125 if (witness_lock_order_check(w1, w)) 1126 return; 1127 1128 /* 1129 * Check for duplicate locks of the same type. Note that we only 1130 * have to check for this on the last lock we just acquired. Any 1131 * other cases will be caught as lock order violations. 1132 */ 1133 mtx_lock_spin(&w_mtx); 1134 witness_lock_order_add(w1, w); 1135 if (w1 == w) { 1136 i = w->w_index; 1137 if (!(lock->lo_flags & LO_DUPOK) && !(flags & LOP_DUPOK) && 1138 !(w_rmatrix[i][i] & WITNESS_REVERSAL)) { 1139 w_rmatrix[i][i] |= WITNESS_REVERSAL; 1140 w->w_reversed = 1; 1141 mtx_unlock_spin(&w_mtx); 1142 printf( 1143 "acquiring duplicate lock of same type: \"%s\"\n", 1144 w->w_name); 1145 printf(" 1st %s @ %s:%d\n", plock->li_lock->lo_name, 1146 plock->li_file, plock->li_line); 1147 printf(" 2nd %s @ %s:%d\n", lock->lo_name, file, line); 1148 witness_debugger(1); 1149 } else 1150 mtx_unlock_spin(&w_mtx); 1151 return; 1152 } 1153 mtx_assert(&w_mtx, MA_OWNED); 1154 1155 /* 1156 * If we know that the the lock we are acquiring comes after 1157 * the lock we most recently acquired in the lock order tree, 1158 * then there is no need for any further checks. 1159 */ 1160 if (isitmychild(w1, w)) 1161 goto out; 1162 1163 for (j = 0, lle = lock_list; lle != NULL; lle = lle->ll_next) { 1164 for (i = lle->ll_count - 1; i >= 0; i--, j++) { 1165 1166 MPASS(j < WITNESS_COUNT); 1167 lock1 = &lle->ll_children[i]; 1168 1169 /* 1170 * Ignore the interlock the first time we see it. 1171 */ 1172 if (interlock != NULL && interlock == lock1->li_lock) { 1173 interlock = NULL; 1174 continue; 1175 } 1176 1177 /* 1178 * If this lock doesn't undergo witness checking, 1179 * then skip it. 1180 */ 1181 w1 = lock1->li_lock->lo_witness; 1182 if (w1 == NULL) { 1183 KASSERT((lock1->li_lock->lo_flags & LO_WITNESS) == 0, 1184 ("lock missing witness structure")); 1185 continue; 1186 } 1187 1188 /* 1189 * If we are locking Giant and this is a sleepable 1190 * lock, then skip it. 1191 */ 1192 if ((lock1->li_lock->lo_flags & LO_SLEEPABLE) != 0 && 1193 lock == &Giant.lock_object) 1194 continue; 1195 1196 /* 1197 * If we are locking a sleepable lock and this lock 1198 * is Giant, then skip it. 1199 */ 1200 if ((lock->lo_flags & LO_SLEEPABLE) != 0 && 1201 lock1->li_lock == &Giant.lock_object) 1202 continue; 1203 1204 /* 1205 * If we are locking a sleepable lock and this lock 1206 * isn't sleepable, we want to treat it as a lock 1207 * order violation to enfore a general lock order of 1208 * sleepable locks before non-sleepable locks. 1209 */ 1210 if (((lock->lo_flags & LO_SLEEPABLE) != 0 && 1211 (lock1->li_lock->lo_flags & LO_SLEEPABLE) == 0)) 1212 goto reversal; 1213 1214 /* 1215 * If we are locking Giant and this is a non-sleepable 1216 * lock, then treat it as a reversal. 1217 */ 1218 if ((lock1->li_lock->lo_flags & LO_SLEEPABLE) == 0 && 1219 lock == &Giant.lock_object) 1220 goto reversal; 1221 1222 /* 1223 * Check the lock order hierarchy for a reveresal. 1224 */ 1225 if (!isitmydescendant(w, w1)) 1226 continue; 1227 reversal: 1228 1229 /* 1230 * We have a lock order violation, check to see if it 1231 * is allowed or has already been yelled about. 1232 */ 1233 #ifdef BLESSING 1234 1235 /* 1236 * If the lock order is blessed, just bail. We don't 1237 * look for other lock order violations though, which 1238 * may be a bug. 1239 */ 1240 if (blessed(w, w1)) 1241 goto out; 1242 #endif 1243 1244 /* Bail if this violation is known */ 1245 if (w_rmatrix[w1->w_index][w->w_index] & WITNESS_REVERSAL) 1246 goto out; 1247 1248 /* Record this as a violation */ 1249 w_rmatrix[w1->w_index][w->w_index] |= WITNESS_REVERSAL; 1250 w_rmatrix[w->w_index][w1->w_index] |= WITNESS_REVERSAL; 1251 w->w_reversed = w1->w_reversed = 1; 1252 witness_increment_graph_generation(); 1253 mtx_unlock_spin(&w_mtx); 1254 1255 /* 1256 * Ok, yell about it. 1257 */ 1258 if (((lock->lo_flags & LO_SLEEPABLE) != 0 && 1259 (lock1->li_lock->lo_flags & LO_SLEEPABLE) == 0)) 1260 printf( 1261 "lock order reversal: (sleepable after non-sleepable)\n"); 1262 else if ((lock1->li_lock->lo_flags & LO_SLEEPABLE) == 0 1263 && lock == &Giant.lock_object) 1264 printf( 1265 "lock order reversal: (Giant after non-sleepable)\n"); 1266 else 1267 printf("lock order reversal:\n"); 1268 1269 /* 1270 * Try to locate an earlier lock with 1271 * witness w in our list. 1272 */ 1273 do { 1274 lock2 = &lle->ll_children[i]; 1275 MPASS(lock2->li_lock != NULL); 1276 if (lock2->li_lock->lo_witness == w) 1277 break; 1278 if (i == 0 && lle->ll_next != NULL) { 1279 lle = lle->ll_next; 1280 i = lle->ll_count - 1; 1281 MPASS(i >= 0 && i < LOCK_NCHILDREN); 1282 } else 1283 i--; 1284 } while (i >= 0); 1285 if (i < 0) { 1286 printf(" 1st %p %s (%s) @ %s:%d\n", 1287 lock1->li_lock, lock1->li_lock->lo_name, 1288 w1->w_name, lock1->li_file, lock1->li_line); 1289 printf(" 2nd %p %s (%s) @ %s:%d\n", lock, 1290 lock->lo_name, w->w_name, file, line); 1291 } else { 1292 printf(" 1st %p %s (%s) @ %s:%d\n", 1293 lock2->li_lock, lock2->li_lock->lo_name, 1294 lock2->li_lock->lo_witness->w_name, 1295 lock2->li_file, lock2->li_line); 1296 printf(" 2nd %p %s (%s) @ %s:%d\n", 1297 lock1->li_lock, lock1->li_lock->lo_name, 1298 w1->w_name, lock1->li_file, lock1->li_line); 1299 printf(" 3rd %p %s (%s) @ %s:%d\n", lock, 1300 lock->lo_name, w->w_name, file, line); 1301 } 1302 witness_debugger(1); 1303 return; 1304 } 1305 } 1306 1307 /* 1308 * If requested, build a new lock order. However, don't build a new 1309 * relationship between a sleepable lock and Giant if it is in the 1310 * wrong direction. The correct lock order is that sleepable locks 1311 * always come before Giant. 1312 */ 1313 if (flags & LOP_NEWORDER && 1314 !(plock->li_lock == &Giant.lock_object && 1315 (lock->lo_flags & LO_SLEEPABLE) != 0)) { 1316 CTR3(KTR_WITNESS, "%s: adding %s as a child of %s", __func__, 1317 w->w_name, plock->li_lock->lo_witness->w_name); 1318 itismychild(plock->li_lock->lo_witness, w); 1319 } 1320 out: 1321 mtx_unlock_spin(&w_mtx); 1322 } 1323 1324 void 1325 witness_lock(struct lock_object *lock, int flags, const char *file, int line) 1326 { 1327 struct lock_list_entry **lock_list, *lle; 1328 struct lock_instance *instance; 1329 struct witness *w; 1330 struct thread *td; 1331 1332 if (witness_cold || witness_watch == -1 || lock->lo_witness == NULL || 1333 panicstr != NULL) 1334 return; 1335 w = lock->lo_witness; 1336 td = curthread; 1337 file = fixup_filename(file); 1338 1339 /* Determine lock list for this lock. */ 1340 if (LOCK_CLASS(lock)->lc_flags & LC_SLEEPLOCK) 1341 lock_list = &td->td_sleeplocks; 1342 else 1343 lock_list = PCPU_PTR(spinlocks); 1344 1345 /* Check to see if we are recursing on a lock we already own. */ 1346 instance = find_instance(*lock_list, lock); 1347 if (instance != NULL) { 1348 instance->li_flags++; 1349 CTR4(KTR_WITNESS, "%s: pid %d recursed on %s r=%d", __func__, 1350 td->td_proc->p_pid, lock->lo_name, 1351 instance->li_flags & LI_RECURSEMASK); 1352 instance->li_file = file; 1353 instance->li_line = line; 1354 return; 1355 } 1356 1357 /* Update per-witness last file and line acquire. */ 1358 w->w_file = file; 1359 w->w_line = line; 1360 1361 /* Find the next open lock instance in the list and fill it. */ 1362 lle = *lock_list; 1363 if (lle == NULL || lle->ll_count == LOCK_NCHILDREN) { 1364 lle = witness_lock_list_get(); 1365 if (lle == NULL) 1366 return; 1367 lle->ll_next = *lock_list; 1368 CTR3(KTR_WITNESS, "%s: pid %d added lle %p", __func__, 1369 td->td_proc->p_pid, lle); 1370 *lock_list = lle; 1371 } 1372 instance = &lle->ll_children[lle->ll_count++]; 1373 instance->li_lock = lock; 1374 instance->li_line = line; 1375 instance->li_file = file; 1376 if ((flags & LOP_EXCLUSIVE) != 0) 1377 instance->li_flags = LI_EXCLUSIVE; 1378 else 1379 instance->li_flags = 0; 1380 CTR4(KTR_WITNESS, "%s: pid %d added %s as lle[%d]", __func__, 1381 td->td_proc->p_pid, lock->lo_name, lle->ll_count - 1); 1382 } 1383 1384 void 1385 witness_upgrade(struct lock_object *lock, int flags, const char *file, int line) 1386 { 1387 struct lock_instance *instance; 1388 struct lock_class *class; 1389 1390 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); 1391 if (lock->lo_witness == NULL || witness_watch == -1 || panicstr != NULL) 1392 return; 1393 class = LOCK_CLASS(lock); 1394 file = fixup_filename(file); 1395 if (witness_watch) { 1396 if ((lock->lo_flags & LO_UPGRADABLE) == 0) 1397 panic("upgrade of non-upgradable lock (%s) %s @ %s:%d", 1398 class->lc_name, lock->lo_name, file, line); 1399 if ((class->lc_flags & LC_SLEEPLOCK) == 0) 1400 panic("upgrade of non-sleep lock (%s) %s @ %s:%d", 1401 class->lc_name, lock->lo_name, file, line); 1402 } 1403 instance = find_instance(curthread->td_sleeplocks, lock); 1404 if (instance == NULL) 1405 panic("upgrade of unlocked lock (%s) %s @ %s:%d", 1406 class->lc_name, lock->lo_name, file, line); 1407 if (witness_watch) { 1408 if ((instance->li_flags & LI_EXCLUSIVE) != 0) 1409 panic("upgrade of exclusive lock (%s) %s @ %s:%d", 1410 class->lc_name, lock->lo_name, file, line); 1411 if ((instance->li_flags & LI_RECURSEMASK) != 0) 1412 panic("upgrade of recursed lock (%s) %s r=%d @ %s:%d", 1413 class->lc_name, lock->lo_name, 1414 instance->li_flags & LI_RECURSEMASK, file, line); 1415 } 1416 instance->li_flags |= LI_EXCLUSIVE; 1417 } 1418 1419 void 1420 witness_downgrade(struct lock_object *lock, int flags, const char *file, 1421 int line) 1422 { 1423 struct lock_instance *instance; 1424 struct lock_class *class; 1425 1426 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); 1427 if (lock->lo_witness == NULL || witness_watch == -1 || panicstr != NULL) 1428 return; 1429 class = LOCK_CLASS(lock); 1430 file = fixup_filename(file); 1431 if (witness_watch) { 1432 if ((lock->lo_flags & LO_UPGRADABLE) == 0) 1433 panic("downgrade of non-upgradable lock (%s) %s @ %s:%d", 1434 class->lc_name, lock->lo_name, file, line); 1435 if ((class->lc_flags & LC_SLEEPLOCK) == 0) 1436 panic("downgrade of non-sleep lock (%s) %s @ %s:%d", 1437 class->lc_name, lock->lo_name, file, line); 1438 } 1439 instance = find_instance(curthread->td_sleeplocks, lock); 1440 if (instance == NULL) 1441 panic("downgrade of unlocked lock (%s) %s @ %s:%d", 1442 class->lc_name, lock->lo_name, file, line); 1443 if (witness_watch) { 1444 if ((instance->li_flags & LI_EXCLUSIVE) == 0) 1445 panic("downgrade of shared lock (%s) %s @ %s:%d", 1446 class->lc_name, lock->lo_name, file, line); 1447 if ((instance->li_flags & LI_RECURSEMASK) != 0) 1448 panic("downgrade of recursed lock (%s) %s r=%d @ %s:%d", 1449 class->lc_name, lock->lo_name, 1450 instance->li_flags & LI_RECURSEMASK, file, line); 1451 } 1452 instance->li_flags &= ~LI_EXCLUSIVE; 1453 } 1454 1455 void 1456 witness_unlock(struct lock_object *lock, int flags, const char *file, int line) 1457 { 1458 struct lock_list_entry **lock_list, *lle; 1459 struct lock_instance *instance; 1460 struct lock_class *class; 1461 struct thread *td; 1462 register_t s; 1463 int i, j; 1464 1465 if (witness_cold || lock->lo_witness == NULL || panicstr != NULL) 1466 return; 1467 td = curthread; 1468 class = LOCK_CLASS(lock); 1469 file = fixup_filename(file); 1470 1471 /* Find lock instance associated with this lock. */ 1472 if (class->lc_flags & LC_SLEEPLOCK) 1473 lock_list = &td->td_sleeplocks; 1474 else 1475 lock_list = PCPU_PTR(spinlocks); 1476 lle = *lock_list; 1477 for (; *lock_list != NULL; lock_list = &(*lock_list)->ll_next) 1478 for (i = 0; i < (*lock_list)->ll_count; i++) { 1479 instance = &(*lock_list)->ll_children[i]; 1480 if (instance->li_lock == lock) 1481 goto found; 1482 } 1483 1484 /* 1485 * When disabling WITNESS through witness_watch we could end up in 1486 * having registered locks in the td_sleeplocks queue. 1487 * We have to make sure we flush these queues, so just search for 1488 * eventual register locks and remove them. 1489 */ 1490 if (witness_watch > 0) 1491 panic("lock (%s) %s not locked @ %s:%d", class->lc_name, 1492 lock->lo_name, file, line); 1493 else 1494 return; 1495 found: 1496 1497 /* First, check for shared/exclusive mismatches. */ 1498 if ((instance->li_flags & LI_EXCLUSIVE) != 0 && witness_watch > 0 && 1499 (flags & LOP_EXCLUSIVE) == 0) { 1500 printf("shared unlock of (%s) %s @ %s:%d\n", class->lc_name, 1501 lock->lo_name, file, line); 1502 printf("while exclusively locked from %s:%d\n", 1503 instance->li_file, instance->li_line); 1504 panic("excl->ushare"); 1505 } 1506 if ((instance->li_flags & LI_EXCLUSIVE) == 0 && witness_watch > 0 && 1507 (flags & LOP_EXCLUSIVE) != 0) { 1508 printf("exclusive unlock of (%s) %s @ %s:%d\n", class->lc_name, 1509 lock->lo_name, file, line); 1510 printf("while share locked from %s:%d\n", instance->li_file, 1511 instance->li_line); 1512 panic("share->uexcl"); 1513 } 1514 /* If we are recursed, unrecurse. */ 1515 if ((instance->li_flags & LI_RECURSEMASK) > 0) { 1516 CTR4(KTR_WITNESS, "%s: pid %d unrecursed on %s r=%d", __func__, 1517 td->td_proc->p_pid, instance->li_lock->lo_name, 1518 instance->li_flags); 1519 instance->li_flags--; 1520 return; 1521 } 1522 /* The lock is now being dropped, check for NORELEASE flag */ 1523 if ((instance->li_flags & LI_NORELEASE) != 0 && witness_watch > 0) { 1524 printf("forbidden unlock of (%s) %s @ %s:%d\n", class->lc_name, 1525 lock->lo_name, file, line); 1526 panic("lock marked norelease"); 1527 } 1528 1529 /* Otherwise, remove this item from the list. */ 1530 s = intr_disable(); 1531 CTR4(KTR_WITNESS, "%s: pid %d removed %s from lle[%d]", __func__, 1532 td->td_proc->p_pid, instance->li_lock->lo_name, 1533 (*lock_list)->ll_count - 1); 1534 for (j = i; j < (*lock_list)->ll_count - 1; j++) 1535 (*lock_list)->ll_children[j] = 1536 (*lock_list)->ll_children[j + 1]; 1537 (*lock_list)->ll_count--; 1538 intr_restore(s); 1539 1540 /* 1541 * In order to reduce contention on w_mtx, we want to keep always an 1542 * head object into lists so that frequent allocation from the 1543 * free witness pool (and subsequent locking) is avoided. 1544 * In order to maintain the current code simple, when the head 1545 * object is totally unloaded it means also that we do not have 1546 * further objects in the list, so the list ownership needs to be 1547 * hand over to another object if the current head needs to be freed. 1548 */ 1549 if ((*lock_list)->ll_count == 0) { 1550 if (*lock_list == lle) { 1551 if (lle->ll_next == NULL) 1552 return; 1553 } else 1554 lle = *lock_list; 1555 *lock_list = lle->ll_next; 1556 CTR3(KTR_WITNESS, "%s: pid %d removed lle %p", __func__, 1557 td->td_proc->p_pid, lle); 1558 witness_lock_list_free(lle); 1559 } 1560 } 1561 1562 void 1563 witness_thread_exit(struct thread *td) 1564 { 1565 struct lock_list_entry *lle; 1566 int i, n; 1567 1568 lle = td->td_sleeplocks; 1569 if (lle == NULL || panicstr != NULL) 1570 return; 1571 if (lle->ll_count != 0) { 1572 for (n = 0; lle != NULL; lle = lle->ll_next) 1573 for (i = lle->ll_count - 1; i >= 0; i--) { 1574 if (n == 0) 1575 printf("Thread %p exiting with the following locks held:\n", 1576 td); 1577 n++; 1578 witness_list_lock(&lle->ll_children[i]); 1579 1580 } 1581 panic("Thread %p cannot exit while holding sleeplocks\n", td); 1582 } 1583 witness_lock_list_free(lle); 1584 } 1585 1586 /* 1587 * Warn if any locks other than 'lock' are held. Flags can be passed in to 1588 * exempt Giant and sleepable locks from the checks as well. If any 1589 * non-exempt locks are held, then a supplied message is printed to the 1590 * console along with a list of the offending locks. If indicated in the 1591 * flags then a failure results in a panic as well. 1592 */ 1593 int 1594 witness_warn(int flags, struct lock_object *lock, const char *fmt, ...) 1595 { 1596 struct lock_list_entry *lock_list, *lle; 1597 struct lock_instance *lock1; 1598 struct thread *td; 1599 va_list ap; 1600 int i, n; 1601 1602 if (witness_cold || witness_watch < 1 || panicstr != NULL) 1603 return (0); 1604 n = 0; 1605 td = curthread; 1606 for (lle = td->td_sleeplocks; lle != NULL; lle = lle->ll_next) 1607 for (i = lle->ll_count - 1; i >= 0; i--) { 1608 lock1 = &lle->ll_children[i]; 1609 if (lock1->li_lock == lock) 1610 continue; 1611 if (flags & WARN_GIANTOK && 1612 lock1->li_lock == &Giant.lock_object) 1613 continue; 1614 if (flags & WARN_SLEEPOK && 1615 (lock1->li_lock->lo_flags & LO_SLEEPABLE) != 0) 1616 continue; 1617 if (n == 0) { 1618 va_start(ap, fmt); 1619 vprintf(fmt, ap); 1620 va_end(ap); 1621 printf(" with the following"); 1622 if (flags & WARN_SLEEPOK) 1623 printf(" non-sleepable"); 1624 printf(" locks held:\n"); 1625 } 1626 n++; 1627 witness_list_lock(lock1); 1628 } 1629 1630 /* 1631 * Pin the thread in order to avoid problems with thread migration. 1632 * Once that all verifies are passed about spinlocks ownership, 1633 * the thread is in a safe path and it can be unpinned. 1634 */ 1635 sched_pin(); 1636 lock_list = PCPU_GET(spinlocks); 1637 if (lock_list != NULL && lock_list->ll_count != 0) { 1638 sched_unpin(); 1639 1640 /* 1641 * We should only have one spinlock and as long as 1642 * the flags cannot match for this locks class, 1643 * check if the first spinlock is the one curthread 1644 * should hold. 1645 */ 1646 lock1 = &lock_list->ll_children[lock_list->ll_count - 1]; 1647 if (lock_list->ll_count == 1 && lock_list->ll_next == NULL && 1648 lock1->li_lock == lock && n == 0) 1649 return (0); 1650 1651 va_start(ap, fmt); 1652 vprintf(fmt, ap); 1653 va_end(ap); 1654 printf(" with the following"); 1655 if (flags & WARN_SLEEPOK) 1656 printf(" non-sleepable"); 1657 printf(" locks held:\n"); 1658 n += witness_list_locks(&lock_list); 1659 } else 1660 sched_unpin(); 1661 if (flags & WARN_PANIC && n) 1662 panic("%s", __func__); 1663 else 1664 witness_debugger(n); 1665 return (n); 1666 } 1667 1668 const char * 1669 witness_file(struct lock_object *lock) 1670 { 1671 struct witness *w; 1672 1673 if (witness_cold || witness_watch < 1 || lock->lo_witness == NULL) 1674 return ("?"); 1675 w = lock->lo_witness; 1676 return (w->w_file); 1677 } 1678 1679 int 1680 witness_line(struct lock_object *lock) 1681 { 1682 struct witness *w; 1683 1684 if (witness_cold || witness_watch < 1 || lock->lo_witness == NULL) 1685 return (0); 1686 w = lock->lo_witness; 1687 return (w->w_line); 1688 } 1689 1690 static struct witness * 1691 enroll(const char *description, struct lock_class *lock_class) 1692 { 1693 struct witness *w; 1694 struct witness_list *typelist; 1695 1696 MPASS(description != NULL); 1697 1698 if (witness_watch == -1 || panicstr != NULL) 1699 return (NULL); 1700 if ((lock_class->lc_flags & LC_SPINLOCK)) { 1701 if (witness_skipspin) 1702 return (NULL); 1703 else 1704 typelist = &w_spin; 1705 } else if ((lock_class->lc_flags & LC_SLEEPLOCK)) 1706 typelist = &w_sleep; 1707 else 1708 panic("lock class %s is not sleep or spin", 1709 lock_class->lc_name); 1710 1711 mtx_lock_spin(&w_mtx); 1712 w = witness_hash_get(description); 1713 if (w) 1714 goto found; 1715 if ((w = witness_get()) == NULL) 1716 return (NULL); 1717 MPASS(strlen(description) < MAX_W_NAME); 1718 strcpy(w->w_name, description); 1719 w->w_class = lock_class; 1720 w->w_refcount = 1; 1721 STAILQ_INSERT_HEAD(&w_all, w, w_list); 1722 if (lock_class->lc_flags & LC_SPINLOCK) { 1723 STAILQ_INSERT_HEAD(&w_spin, w, w_typelist); 1724 w_spin_cnt++; 1725 } else if (lock_class->lc_flags & LC_SLEEPLOCK) { 1726 STAILQ_INSERT_HEAD(&w_sleep, w, w_typelist); 1727 w_sleep_cnt++; 1728 } 1729 1730 /* Insert new witness into the hash */ 1731 witness_hash_put(w); 1732 witness_increment_graph_generation(); 1733 mtx_unlock_spin(&w_mtx); 1734 return (w); 1735 found: 1736 w->w_refcount++; 1737 mtx_unlock_spin(&w_mtx); 1738 if (lock_class != w->w_class) 1739 panic( 1740 "lock (%s) %s does not match earlier (%s) lock", 1741 description, lock_class->lc_name, 1742 w->w_class->lc_name); 1743 return (w); 1744 } 1745 1746 static void 1747 depart(struct witness *w) 1748 { 1749 struct witness_list *list; 1750 1751 MPASS(w->w_refcount == 0); 1752 if (w->w_class->lc_flags & LC_SLEEPLOCK) { 1753 list = &w_sleep; 1754 w_sleep_cnt--; 1755 } else { 1756 list = &w_spin; 1757 w_spin_cnt--; 1758 } 1759 /* 1760 * Set file to NULL as it may point into a loadable module. 1761 */ 1762 w->w_file = NULL; 1763 w->w_line = 0; 1764 witness_increment_graph_generation(); 1765 } 1766 1767 1768 static void 1769 adopt(struct witness *parent, struct witness *child) 1770 { 1771 int pi, ci, i, j; 1772 1773 if (witness_cold == 0) 1774 mtx_assert(&w_mtx, MA_OWNED); 1775 1776 /* If the relationship is already known, there's no work to be done. */ 1777 if (isitmychild(parent, child)) 1778 return; 1779 1780 /* When the structure of the graph changes, bump up the generation. */ 1781 witness_increment_graph_generation(); 1782 1783 /* 1784 * The hard part ... create the direct relationship, then propagate all 1785 * indirect relationships. 1786 */ 1787 pi = parent->w_index; 1788 ci = child->w_index; 1789 WITNESS_INDEX_ASSERT(pi); 1790 WITNESS_INDEX_ASSERT(ci); 1791 MPASS(pi != ci); 1792 w_rmatrix[pi][ci] |= WITNESS_PARENT; 1793 w_rmatrix[ci][pi] |= WITNESS_CHILD; 1794 1795 /* 1796 * If parent was not already an ancestor of child, 1797 * then we increment the descendant and ancestor counters. 1798 */ 1799 if ((w_rmatrix[pi][ci] & WITNESS_ANCESTOR) == 0) { 1800 parent->w_num_descendants++; 1801 child->w_num_ancestors++; 1802 } 1803 1804 /* 1805 * Find each ancestor of 'pi'. Note that 'pi' itself is counted as 1806 * an ancestor of 'pi' during this loop. 1807 */ 1808 for (i = 1; i <= w_max_used_index; i++) { 1809 if ((w_rmatrix[i][pi] & WITNESS_ANCESTOR_MASK) == 0 && 1810 (i != pi)) 1811 continue; 1812 1813 /* Find each descendant of 'i' and mark it as a descendant. */ 1814 for (j = 1; j <= w_max_used_index; j++) { 1815 1816 /* 1817 * Skip children that are already marked as 1818 * descendants of 'i'. 1819 */ 1820 if (w_rmatrix[i][j] & WITNESS_ANCESTOR_MASK) 1821 continue; 1822 1823 /* 1824 * We are only interested in descendants of 'ci'. Note 1825 * that 'ci' itself is counted as a descendant of 'ci'. 1826 */ 1827 if ((w_rmatrix[ci][j] & WITNESS_ANCESTOR_MASK) == 0 && 1828 (j != ci)) 1829 continue; 1830 w_rmatrix[i][j] |= WITNESS_ANCESTOR; 1831 w_rmatrix[j][i] |= WITNESS_DESCENDANT; 1832 w_data[i].w_num_descendants++; 1833 w_data[j].w_num_ancestors++; 1834 1835 /* 1836 * Make sure we aren't marking a node as both an 1837 * ancestor and descendant. We should have caught 1838 * this as a lock order reversal earlier. 1839 */ 1840 if ((w_rmatrix[i][j] & WITNESS_ANCESTOR_MASK) && 1841 (w_rmatrix[i][j] & WITNESS_DESCENDANT_MASK)) { 1842 printf("witness rmatrix paradox! [%d][%d]=%d " 1843 "both ancestor and descendant\n", 1844 i, j, w_rmatrix[i][j]); 1845 kdb_backtrace(); 1846 printf("Witness disabled.\n"); 1847 witness_watch = -1; 1848 } 1849 if ((w_rmatrix[j][i] & WITNESS_ANCESTOR_MASK) && 1850 (w_rmatrix[j][i] & WITNESS_DESCENDANT_MASK)) { 1851 printf("witness rmatrix paradox! [%d][%d]=%d " 1852 "both ancestor and descendant\n", 1853 j, i, w_rmatrix[j][i]); 1854 kdb_backtrace(); 1855 printf("Witness disabled.\n"); 1856 witness_watch = -1; 1857 } 1858 } 1859 } 1860 } 1861 1862 static void 1863 itismychild(struct witness *parent, struct witness *child) 1864 { 1865 1866 MPASS(child != NULL && parent != NULL); 1867 if (witness_cold == 0) 1868 mtx_assert(&w_mtx, MA_OWNED); 1869 1870 if (!witness_lock_type_equal(parent, child)) { 1871 if (witness_cold == 0) 1872 mtx_unlock_spin(&w_mtx); 1873 panic("%s: parent \"%s\" (%s) and child \"%s\" (%s) are not " 1874 "the same lock type", __func__, parent->w_name, 1875 parent->w_class->lc_name, child->w_name, 1876 child->w_class->lc_name); 1877 } 1878 adopt(parent, child); 1879 } 1880 1881 /* 1882 * Generic code for the isitmy*() functions. The rmask parameter is the 1883 * expected relationship of w1 to w2. 1884 */ 1885 static int 1886 _isitmyx(struct witness *w1, struct witness *w2, int rmask, const char *fname) 1887 { 1888 unsigned char r1, r2; 1889 int i1, i2; 1890 1891 i1 = w1->w_index; 1892 i2 = w2->w_index; 1893 WITNESS_INDEX_ASSERT(i1); 1894 WITNESS_INDEX_ASSERT(i2); 1895 r1 = w_rmatrix[i1][i2] & WITNESS_RELATED_MASK; 1896 r2 = w_rmatrix[i2][i1] & WITNESS_RELATED_MASK; 1897 1898 /* The flags on one better be the inverse of the flags on the other */ 1899 if (!((WITNESS_ATOD(r1) == r2 && WITNESS_DTOA(r2) == r1) || 1900 (WITNESS_DTOA(r1) == r2 && WITNESS_ATOD(r2) == r1))) { 1901 printf("%s: rmatrix mismatch between %s (index %d) and %s " 1902 "(index %d): w_rmatrix[%d][%d] == %hhx but " 1903 "w_rmatrix[%d][%d] == %hhx\n", 1904 fname, w1->w_name, i1, w2->w_name, i2, i1, i2, r1, 1905 i2, i1, r2); 1906 kdb_backtrace(); 1907 printf("Witness disabled.\n"); 1908 witness_watch = -1; 1909 } 1910 return (r1 & rmask); 1911 } 1912 1913 /* 1914 * Checks if @child is a direct child of @parent. 1915 */ 1916 static int 1917 isitmychild(struct witness *parent, struct witness *child) 1918 { 1919 1920 return (_isitmyx(parent, child, WITNESS_PARENT, __func__)); 1921 } 1922 1923 /* 1924 * Checks if @descendant is a direct or inderect descendant of @ancestor. 1925 */ 1926 static int 1927 isitmydescendant(struct witness *ancestor, struct witness *descendant) 1928 { 1929 1930 return (_isitmyx(ancestor, descendant, WITNESS_ANCESTOR_MASK, 1931 __func__)); 1932 } 1933 1934 #ifdef BLESSING 1935 static int 1936 blessed(struct witness *w1, struct witness *w2) 1937 { 1938 int i; 1939 struct witness_blessed *b; 1940 1941 for (i = 0; i < blessed_count; i++) { 1942 b = &blessed_list[i]; 1943 if (strcmp(w1->w_name, b->b_lock1) == 0) { 1944 if (strcmp(w2->w_name, b->b_lock2) == 0) 1945 return (1); 1946 continue; 1947 } 1948 if (strcmp(w1->w_name, b->b_lock2) == 0) 1949 if (strcmp(w2->w_name, b->b_lock1) == 0) 1950 return (1); 1951 } 1952 return (0); 1953 } 1954 #endif 1955 1956 static struct witness * 1957 witness_get(void) 1958 { 1959 struct witness *w; 1960 int index; 1961 1962 if (witness_cold == 0) 1963 mtx_assert(&w_mtx, MA_OWNED); 1964 1965 if (witness_watch == -1) { 1966 mtx_unlock_spin(&w_mtx); 1967 return (NULL); 1968 } 1969 if (STAILQ_EMPTY(&w_free)) { 1970 witness_watch = -1; 1971 mtx_unlock_spin(&w_mtx); 1972 printf("WITNESS: unable to allocate a new witness object\n"); 1973 return (NULL); 1974 } 1975 w = STAILQ_FIRST(&w_free); 1976 STAILQ_REMOVE_HEAD(&w_free, w_list); 1977 w_free_cnt--; 1978 index = w->w_index; 1979 MPASS(index > 0 && index == w_max_used_index+1 && 1980 index < WITNESS_COUNT); 1981 bzero(w, sizeof(*w)); 1982 w->w_index = index; 1983 if (index > w_max_used_index) 1984 w_max_used_index = index; 1985 return (w); 1986 } 1987 1988 static void 1989 witness_free(struct witness *w) 1990 { 1991 1992 STAILQ_INSERT_HEAD(&w_free, w, w_list); 1993 w_free_cnt++; 1994 } 1995 1996 static struct lock_list_entry * 1997 witness_lock_list_get(void) 1998 { 1999 struct lock_list_entry *lle; 2000 2001 if (witness_watch == -1) 2002 return (NULL); 2003 mtx_lock_spin(&w_mtx); 2004 lle = w_lock_list_free; 2005 if (lle == NULL) { 2006 witness_watch = -1; 2007 mtx_unlock_spin(&w_mtx); 2008 printf("%s: witness exhausted\n", __func__); 2009 return (NULL); 2010 } 2011 w_lock_list_free = lle->ll_next; 2012 mtx_unlock_spin(&w_mtx); 2013 bzero(lle, sizeof(*lle)); 2014 return (lle); 2015 } 2016 2017 static void 2018 witness_lock_list_free(struct lock_list_entry *lle) 2019 { 2020 2021 mtx_lock_spin(&w_mtx); 2022 lle->ll_next = w_lock_list_free; 2023 w_lock_list_free = lle; 2024 mtx_unlock_spin(&w_mtx); 2025 } 2026 2027 static struct lock_instance * 2028 find_instance(struct lock_list_entry *list, struct lock_object *lock) 2029 { 2030 struct lock_list_entry *lle; 2031 struct lock_instance *instance; 2032 int i; 2033 2034 for (lle = list; lle != NULL; lle = lle->ll_next) 2035 for (i = lle->ll_count - 1; i >= 0; i--) { 2036 instance = &lle->ll_children[i]; 2037 if (instance->li_lock == lock) 2038 return (instance); 2039 } 2040 return (NULL); 2041 } 2042 2043 static void 2044 witness_list_lock(struct lock_instance *instance) 2045 { 2046 struct lock_object *lock; 2047 2048 lock = instance->li_lock; 2049 printf("%s %s %s", (instance->li_flags & LI_EXCLUSIVE) != 0 ? 2050 "exclusive" : "shared", LOCK_CLASS(lock)->lc_name, lock->lo_name); 2051 if (lock->lo_witness->w_name != lock->lo_name) 2052 printf(" (%s)", lock->lo_witness->w_name); 2053 printf(" r = %d (%p) locked @ %s:%d\n", 2054 instance->li_flags & LI_RECURSEMASK, lock, instance->li_file, 2055 instance->li_line); 2056 } 2057 2058 #ifdef DDB 2059 static int 2060 witness_thread_has_locks(struct thread *td) 2061 { 2062 2063 if (td->td_sleeplocks == NULL) 2064 return (0); 2065 return (td->td_sleeplocks->ll_count != 0); 2066 } 2067 2068 static int 2069 witness_proc_has_locks(struct proc *p) 2070 { 2071 struct thread *td; 2072 2073 FOREACH_THREAD_IN_PROC(p, td) { 2074 if (witness_thread_has_locks(td)) 2075 return (1); 2076 } 2077 return (0); 2078 } 2079 #endif 2080 2081 int 2082 witness_list_locks(struct lock_list_entry **lock_list) 2083 { 2084 struct lock_list_entry *lle; 2085 int i, nheld; 2086 2087 nheld = 0; 2088 for (lle = *lock_list; lle != NULL; lle = lle->ll_next) 2089 for (i = lle->ll_count - 1; i >= 0; i--) { 2090 witness_list_lock(&lle->ll_children[i]); 2091 nheld++; 2092 } 2093 return (nheld); 2094 } 2095 2096 /* 2097 * This is a bit risky at best. We call this function when we have timed 2098 * out acquiring a spin lock, and we assume that the other CPU is stuck 2099 * with this lock held. So, we go groveling around in the other CPU's 2100 * per-cpu data to try to find the lock instance for this spin lock to 2101 * see when it was last acquired. 2102 */ 2103 void 2104 witness_display_spinlock(struct lock_object *lock, struct thread *owner) 2105 { 2106 struct lock_instance *instance; 2107 struct pcpu *pc; 2108 2109 if (owner->td_critnest == 0 || owner->td_oncpu == NOCPU) 2110 return; 2111 pc = pcpu_find(owner->td_oncpu); 2112 instance = find_instance(pc->pc_spinlocks, lock); 2113 if (instance != NULL) 2114 witness_list_lock(instance); 2115 } 2116 2117 void 2118 witness_save(struct lock_object *lock, const char **filep, int *linep) 2119 { 2120 struct lock_list_entry *lock_list; 2121 struct lock_instance *instance; 2122 struct lock_class *class; 2123 2124 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); 2125 if (lock->lo_witness == NULL || witness_watch == -1 || panicstr != NULL) 2126 return; 2127 class = LOCK_CLASS(lock); 2128 if (class->lc_flags & LC_SLEEPLOCK) 2129 lock_list = curthread->td_sleeplocks; 2130 else { 2131 if (witness_skipspin) 2132 return; 2133 lock_list = PCPU_GET(spinlocks); 2134 } 2135 instance = find_instance(lock_list, lock); 2136 if (instance == NULL) 2137 panic("%s: lock (%s) %s not locked", __func__, 2138 class->lc_name, lock->lo_name); 2139 *filep = instance->li_file; 2140 *linep = instance->li_line; 2141 } 2142 2143 void 2144 witness_restore(struct lock_object *lock, const char *file, int line) 2145 { 2146 struct lock_list_entry *lock_list; 2147 struct lock_instance *instance; 2148 struct lock_class *class; 2149 2150 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); 2151 if (lock->lo_witness == NULL || witness_watch == -1 || panicstr != NULL) 2152 return; 2153 class = LOCK_CLASS(lock); 2154 if (class->lc_flags & LC_SLEEPLOCK) 2155 lock_list = curthread->td_sleeplocks; 2156 else { 2157 if (witness_skipspin) 2158 return; 2159 lock_list = PCPU_GET(spinlocks); 2160 } 2161 instance = find_instance(lock_list, lock); 2162 if (instance == NULL) 2163 panic("%s: lock (%s) %s not locked", __func__, 2164 class->lc_name, lock->lo_name); 2165 lock->lo_witness->w_file = file; 2166 lock->lo_witness->w_line = line; 2167 instance->li_file = file; 2168 instance->li_line = line; 2169 } 2170 2171 void 2172 witness_assert(struct lock_object *lock, int flags, const char *file, int line) 2173 { 2174 #ifdef INVARIANT_SUPPORT 2175 struct lock_instance *instance; 2176 struct lock_class *class; 2177 2178 if (lock->lo_witness == NULL || witness_watch < 1 || panicstr != NULL) 2179 return; 2180 class = LOCK_CLASS(lock); 2181 if ((class->lc_flags & LC_SLEEPLOCK) != 0) 2182 instance = find_instance(curthread->td_sleeplocks, lock); 2183 else if ((class->lc_flags & LC_SPINLOCK) != 0) 2184 instance = find_instance(PCPU_GET(spinlocks), lock); 2185 else { 2186 panic("Lock (%s) %s is not sleep or spin!", 2187 class->lc_name, lock->lo_name); 2188 } 2189 file = fixup_filename(file); 2190 switch (flags) { 2191 case LA_UNLOCKED: 2192 if (instance != NULL) 2193 panic("Lock (%s) %s locked @ %s:%d.", 2194 class->lc_name, lock->lo_name, file, line); 2195 break; 2196 case LA_LOCKED: 2197 case LA_LOCKED | LA_RECURSED: 2198 case LA_LOCKED | LA_NOTRECURSED: 2199 case LA_SLOCKED: 2200 case LA_SLOCKED | LA_RECURSED: 2201 case LA_SLOCKED | LA_NOTRECURSED: 2202 case LA_XLOCKED: 2203 case LA_XLOCKED | LA_RECURSED: 2204 case LA_XLOCKED | LA_NOTRECURSED: 2205 if (instance == NULL) { 2206 panic("Lock (%s) %s not locked @ %s:%d.", 2207 class->lc_name, lock->lo_name, file, line); 2208 break; 2209 } 2210 if ((flags & LA_XLOCKED) != 0 && 2211 (instance->li_flags & LI_EXCLUSIVE) == 0) 2212 panic("Lock (%s) %s not exclusively locked @ %s:%d.", 2213 class->lc_name, lock->lo_name, file, line); 2214 if ((flags & LA_SLOCKED) != 0 && 2215 (instance->li_flags & LI_EXCLUSIVE) != 0) 2216 panic("Lock (%s) %s exclusively locked @ %s:%d.", 2217 class->lc_name, lock->lo_name, file, line); 2218 if ((flags & LA_RECURSED) != 0 && 2219 (instance->li_flags & LI_RECURSEMASK) == 0) 2220 panic("Lock (%s) %s not recursed @ %s:%d.", 2221 class->lc_name, lock->lo_name, file, line); 2222 if ((flags & LA_NOTRECURSED) != 0 && 2223 (instance->li_flags & LI_RECURSEMASK) != 0) 2224 panic("Lock (%s) %s recursed @ %s:%d.", 2225 class->lc_name, lock->lo_name, file, line); 2226 break; 2227 default: 2228 panic("Invalid lock assertion at %s:%d.", file, line); 2229 2230 } 2231 #endif /* INVARIANT_SUPPORT */ 2232 } 2233 2234 static void 2235 witness_setflag(struct lock_object *lock, int flag, int set) 2236 { 2237 struct lock_list_entry *lock_list; 2238 struct lock_instance *instance; 2239 struct lock_class *class; 2240 2241 if (lock->lo_witness == NULL || witness_watch == -1 || panicstr != NULL) 2242 return; 2243 class = LOCK_CLASS(lock); 2244 if (class->lc_flags & LC_SLEEPLOCK) 2245 lock_list = curthread->td_sleeplocks; 2246 else { 2247 if (witness_skipspin) 2248 return; 2249 lock_list = PCPU_GET(spinlocks); 2250 } 2251 instance = find_instance(lock_list, lock); 2252 if (instance == NULL) 2253 panic("%s: lock (%s) %s not locked", __func__, 2254 class->lc_name, lock->lo_name); 2255 2256 if (set) 2257 instance->li_flags |= flag; 2258 else 2259 instance->li_flags &= ~flag; 2260 } 2261 2262 void 2263 witness_norelease(struct lock_object *lock) 2264 { 2265 2266 witness_setflag(lock, LI_NORELEASE, 1); 2267 } 2268 2269 void 2270 witness_releaseok(struct lock_object *lock) 2271 { 2272 2273 witness_setflag(lock, LI_NORELEASE, 0); 2274 } 2275 2276 #ifdef DDB 2277 static void 2278 witness_ddb_list(struct thread *td) 2279 { 2280 2281 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); 2282 KASSERT(kdb_active, ("%s: not in the debugger", __func__)); 2283 2284 if (witness_watch < 1) 2285 return; 2286 2287 witness_list_locks(&td->td_sleeplocks); 2288 2289 /* 2290 * We only handle spinlocks if td == curthread. This is somewhat broken 2291 * if td is currently executing on some other CPU and holds spin locks 2292 * as we won't display those locks. If we had a MI way of getting 2293 * the per-cpu data for a given cpu then we could use 2294 * td->td_oncpu to get the list of spinlocks for this thread 2295 * and "fix" this. 2296 * 2297 * That still wouldn't really fix this unless we locked the scheduler 2298 * lock or stopped the other CPU to make sure it wasn't changing the 2299 * list out from under us. It is probably best to just not try to 2300 * handle threads on other CPU's for now. 2301 */ 2302 if (td == curthread && PCPU_GET(spinlocks) != NULL) 2303 witness_list_locks(PCPU_PTR(spinlocks)); 2304 } 2305 2306 DB_SHOW_COMMAND(locks, db_witness_list) 2307 { 2308 struct thread *td; 2309 2310 if (have_addr) 2311 td = db_lookup_thread(addr, TRUE); 2312 else 2313 td = kdb_thread; 2314 witness_ddb_list(td); 2315 } 2316 2317 DB_SHOW_ALL_COMMAND(locks, db_witness_list_all) 2318 { 2319 struct thread *td; 2320 struct proc *p; 2321 2322 /* 2323 * It would be nice to list only threads and processes that actually 2324 * held sleep locks, but that information is currently not exported 2325 * by WITNESS. 2326 */ 2327 FOREACH_PROC_IN_SYSTEM(p) { 2328 if (!witness_proc_has_locks(p)) 2329 continue; 2330 FOREACH_THREAD_IN_PROC(p, td) { 2331 if (!witness_thread_has_locks(td)) 2332 continue; 2333 db_printf("Process %d (%s) thread %p (%d)\n", p->p_pid, 2334 p->p_comm, td, td->td_tid); 2335 witness_ddb_list(td); 2336 } 2337 } 2338 } 2339 DB_SHOW_ALIAS(alllocks, db_witness_list_all) 2340 2341 DB_SHOW_COMMAND(witness, db_witness_display) 2342 { 2343 2344 witness_ddb_display(db_printf); 2345 } 2346 #endif 2347 2348 static int 2349 sysctl_debug_witness_badstacks(SYSCTL_HANDLER_ARGS) 2350 { 2351 struct witness_lock_order_data *data1, *data2, *tmp_data1, *tmp_data2; 2352 struct witness *tmp_w1, *tmp_w2, *w1, *w2; 2353 struct sbuf *sb; 2354 u_int w_rmatrix1, w_rmatrix2; 2355 int error, generation, i, j; 2356 2357 tmp_data1 = NULL; 2358 tmp_data2 = NULL; 2359 tmp_w1 = NULL; 2360 tmp_w2 = NULL; 2361 if (witness_watch < 1) { 2362 error = SYSCTL_OUT(req, w_notrunning, sizeof(w_notrunning)); 2363 return (error); 2364 } 2365 if (witness_cold) { 2366 error = SYSCTL_OUT(req, w_stillcold, sizeof(w_stillcold)); 2367 return (error); 2368 } 2369 error = 0; 2370 sb = sbuf_new(NULL, NULL, BADSTACK_SBUF_SIZE, SBUF_AUTOEXTEND); 2371 if (sb == NULL) 2372 return (ENOMEM); 2373 2374 /* Allocate and init temporary storage space. */ 2375 tmp_w1 = malloc(sizeof(struct witness), M_TEMP, M_WAITOK | M_ZERO); 2376 tmp_w2 = malloc(sizeof(struct witness), M_TEMP, M_WAITOK | M_ZERO); 2377 tmp_data1 = malloc(sizeof(struct witness_lock_order_data), M_TEMP, 2378 M_WAITOK | M_ZERO); 2379 tmp_data2 = malloc(sizeof(struct witness_lock_order_data), M_TEMP, 2380 M_WAITOK | M_ZERO); 2381 stack_zero(&tmp_data1->wlod_stack); 2382 stack_zero(&tmp_data2->wlod_stack); 2383 2384 restart: 2385 mtx_lock_spin(&w_mtx); 2386 generation = w_generation; 2387 mtx_unlock_spin(&w_mtx); 2388 sbuf_printf(sb, "Number of known direct relationships is %d\n", 2389 w_lohash.wloh_count); 2390 for (i = 1; i < w_max_used_index; i++) { 2391 mtx_lock_spin(&w_mtx); 2392 if (generation != w_generation) { 2393 mtx_unlock_spin(&w_mtx); 2394 2395 /* The graph has changed, try again. */ 2396 req->oldidx = 0; 2397 sbuf_clear(sb); 2398 goto restart; 2399 } 2400 2401 w1 = &w_data[i]; 2402 if (w1->w_reversed == 0) { 2403 mtx_unlock_spin(&w_mtx); 2404 continue; 2405 } 2406 2407 /* Copy w1 locally so we can release the spin lock. */ 2408 *tmp_w1 = *w1; 2409 mtx_unlock_spin(&w_mtx); 2410 2411 if (tmp_w1->w_reversed == 0) 2412 continue; 2413 for (j = 1; j < w_max_used_index; j++) { 2414 if ((w_rmatrix[i][j] & WITNESS_REVERSAL) == 0 || i > j) 2415 continue; 2416 2417 mtx_lock_spin(&w_mtx); 2418 if (generation != w_generation) { 2419 mtx_unlock_spin(&w_mtx); 2420 2421 /* The graph has changed, try again. */ 2422 req->oldidx = 0; 2423 sbuf_clear(sb); 2424 goto restart; 2425 } 2426 2427 w2 = &w_data[j]; 2428 data1 = witness_lock_order_get(w1, w2); 2429 data2 = witness_lock_order_get(w2, w1); 2430 2431 /* 2432 * Copy information locally so we can release the 2433 * spin lock. 2434 */ 2435 *tmp_w2 = *w2; 2436 w_rmatrix1 = (unsigned int)w_rmatrix[i][j]; 2437 w_rmatrix2 = (unsigned int)w_rmatrix[j][i]; 2438 2439 if (data1) { 2440 stack_zero(&tmp_data1->wlod_stack); 2441 stack_copy(&data1->wlod_stack, 2442 &tmp_data1->wlod_stack); 2443 } 2444 if (data2 && data2 != data1) { 2445 stack_zero(&tmp_data2->wlod_stack); 2446 stack_copy(&data2->wlod_stack, 2447 &tmp_data2->wlod_stack); 2448 } 2449 mtx_unlock_spin(&w_mtx); 2450 2451 sbuf_printf(sb, 2452 "\nLock order reversal between \"%s\"(%s) and \"%s\"(%s)!\n", 2453 tmp_w1->w_name, tmp_w1->w_class->lc_name, 2454 tmp_w2->w_name, tmp_w2->w_class->lc_name); 2455 #if 0 2456 sbuf_printf(sb, 2457 "w_rmatrix[%s][%s] == %x, w_rmatrix[%s][%s] == %x\n", 2458 tmp_w1->name, tmp_w2->w_name, w_rmatrix1, 2459 tmp_w2->name, tmp_w1->w_name, w_rmatrix2); 2460 #endif 2461 if (data1) { 2462 sbuf_printf(sb, 2463 "Lock order \"%s\"(%s) -> \"%s\"(%s) first seen at:\n", 2464 tmp_w1->w_name, tmp_w1->w_class->lc_name, 2465 tmp_w2->w_name, tmp_w2->w_class->lc_name); 2466 stack_sbuf_print(sb, &tmp_data1->wlod_stack); 2467 sbuf_printf(sb, "\n"); 2468 } 2469 if (data2 && data2 != data1) { 2470 sbuf_printf(sb, 2471 "Lock order \"%s\"(%s) -> \"%s\"(%s) first seen at:\n", 2472 tmp_w2->w_name, tmp_w2->w_class->lc_name, 2473 tmp_w1->w_name, tmp_w1->w_class->lc_name); 2474 stack_sbuf_print(sb, &tmp_data2->wlod_stack); 2475 sbuf_printf(sb, "\n"); 2476 } 2477 } 2478 } 2479 mtx_lock_spin(&w_mtx); 2480 if (generation != w_generation) { 2481 mtx_unlock_spin(&w_mtx); 2482 2483 /* 2484 * The graph changed while we were printing stack data, 2485 * try again. 2486 */ 2487 req->oldidx = 0; 2488 sbuf_clear(sb); 2489 goto restart; 2490 } 2491 mtx_unlock_spin(&w_mtx); 2492 2493 /* Free temporary storage space. */ 2494 free(tmp_data1, M_TEMP); 2495 free(tmp_data2, M_TEMP); 2496 free(tmp_w1, M_TEMP); 2497 free(tmp_w2, M_TEMP); 2498 2499 sbuf_finish(sb); 2500 error = SYSCTL_OUT(req, sbuf_data(sb), sbuf_len(sb) + 1); 2501 sbuf_delete(sb); 2502 2503 return (error); 2504 } 2505 2506 static int 2507 sysctl_debug_witness_fullgraph(SYSCTL_HANDLER_ARGS) 2508 { 2509 struct witness *w; 2510 struct sbuf *sb; 2511 int error; 2512 2513 if (witness_watch < 1) { 2514 error = SYSCTL_OUT(req, w_notrunning, sizeof(w_notrunning)); 2515 return (error); 2516 } 2517 if (witness_cold) { 2518 error = SYSCTL_OUT(req, w_stillcold, sizeof(w_stillcold)); 2519 return (error); 2520 } 2521 error = 0; 2522 sb = sbuf_new(NULL, NULL, FULLGRAPH_SBUF_SIZE, SBUF_FIXEDLEN); 2523 if (sb == NULL) 2524 return (ENOMEM); 2525 sbuf_printf(sb, "\n"); 2526 2527 mtx_lock_spin(&w_mtx); 2528 STAILQ_FOREACH(w, &w_all, w_list) 2529 w->w_displayed = 0; 2530 STAILQ_FOREACH(w, &w_all, w_list) 2531 witness_add_fullgraph(sb, w); 2532 mtx_unlock_spin(&w_mtx); 2533 2534 /* 2535 * While using SBUF_FIXEDLEN, check if the sbuf overflowed. 2536 */ 2537 if (sbuf_overflowed(sb)) { 2538 sbuf_delete(sb); 2539 panic("%s: sbuf overflowed, bump FULLGRAPH_SBUF_SIZE value\n", 2540 __func__); 2541 } 2542 2543 /* 2544 * Close the sbuf and return to userland. 2545 */ 2546 sbuf_finish(sb); 2547 error = SYSCTL_OUT(req, sbuf_data(sb), sbuf_len(sb) + 1); 2548 sbuf_delete(sb); 2549 2550 return (error); 2551 } 2552 2553 static int 2554 sysctl_debug_witness_watch(SYSCTL_HANDLER_ARGS) 2555 { 2556 int error, value; 2557 2558 value = witness_watch; 2559 error = sysctl_handle_int(oidp, &value, 0, req); 2560 if (error != 0 || req->newptr == NULL) 2561 return (error); 2562 if (value > 1 || value < -1 || 2563 (witness_watch == -1 && value != witness_watch)) 2564 return (EINVAL); 2565 witness_watch = value; 2566 return (0); 2567 } 2568 2569 static void 2570 witness_add_fullgraph(struct sbuf *sb, struct witness *w) 2571 { 2572 int i; 2573 2574 if (w->w_displayed != 0 || (w->w_file == NULL && w->w_line == 0)) 2575 return; 2576 w->w_displayed = 1; 2577 2578 WITNESS_INDEX_ASSERT(w->w_index); 2579 for (i = 1; i <= w_max_used_index; i++) { 2580 if (w_rmatrix[w->w_index][i] & WITNESS_PARENT) { 2581 sbuf_printf(sb, "\"%s\",\"%s\"\n", w->w_name, 2582 w_data[i].w_name); 2583 witness_add_fullgraph(sb, &w_data[i]); 2584 } 2585 } 2586 } 2587 2588 /* 2589 * A simple hash function. Takes a key pointer and a key size. If size == 0, 2590 * interprets the key as a string and reads until the null 2591 * terminator. Otherwise, reads the first size bytes. Returns an unsigned 32-bit 2592 * hash value computed from the key. 2593 */ 2594 static uint32_t 2595 witness_hash_djb2(const uint8_t *key, uint32_t size) 2596 { 2597 unsigned int hash = 5381; 2598 int i; 2599 2600 /* hash = hash * 33 + key[i] */ 2601 if (size) 2602 for (i = 0; i < size; i++) 2603 hash = ((hash << 5) + hash) + (unsigned int)key[i]; 2604 else 2605 for (i = 0; key[i] != 0; i++) 2606 hash = ((hash << 5) + hash) + (unsigned int)key[i]; 2607 2608 return (hash); 2609 } 2610 2611 2612 /* 2613 * Initializes the two witness hash tables. Called exactly once from 2614 * witness_initialize(). 2615 */ 2616 static void 2617 witness_init_hash_tables(void) 2618 { 2619 int i; 2620 2621 MPASS(witness_cold); 2622 2623 /* Initialize the hash tables. */ 2624 for (i = 0; i < WITNESS_HASH_SIZE; i++) 2625 w_hash.wh_array[i] = NULL; 2626 2627 w_hash.wh_size = WITNESS_HASH_SIZE; 2628 w_hash.wh_count = 0; 2629 2630 /* Initialize the lock order data hash. */ 2631 w_lofree = NULL; 2632 for (i = 0; i < WITNESS_LO_DATA_COUNT; i++) { 2633 memset(&w_lodata[i], 0, sizeof(w_lodata[i])); 2634 w_lodata[i].wlod_next = w_lofree; 2635 w_lofree = &w_lodata[i]; 2636 } 2637 w_lohash.wloh_size = WITNESS_LO_HASH_SIZE; 2638 w_lohash.wloh_count = 0; 2639 for (i = 0; i < WITNESS_LO_HASH_SIZE; i++) 2640 w_lohash.wloh_array[i] = NULL; 2641 } 2642 2643 static struct witness * 2644 witness_hash_get(const char *key) 2645 { 2646 struct witness *w; 2647 uint32_t hash; 2648 2649 MPASS(key != NULL); 2650 if (witness_cold == 0) 2651 mtx_assert(&w_mtx, MA_OWNED); 2652 hash = witness_hash_djb2(key, 0) % w_hash.wh_size; 2653 w = w_hash.wh_array[hash]; 2654 while (w != NULL) { 2655 if (strcmp(w->w_name, key) == 0) 2656 goto out; 2657 w = w->w_hash_next; 2658 } 2659 2660 out: 2661 return (w); 2662 } 2663 2664 static void 2665 witness_hash_put(struct witness *w) 2666 { 2667 uint32_t hash; 2668 2669 MPASS(w != NULL); 2670 MPASS(w->w_name != NULL); 2671 if (witness_cold == 0) 2672 mtx_assert(&w_mtx, MA_OWNED); 2673 KASSERT(witness_hash_get(w->w_name) == NULL, 2674 ("%s: trying to add a hash entry that already exists!", __func__)); 2675 KASSERT(w->w_hash_next == NULL, 2676 ("%s: w->w_hash_next != NULL", __func__)); 2677 2678 hash = witness_hash_djb2(w->w_name, 0) % w_hash.wh_size; 2679 w->w_hash_next = w_hash.wh_array[hash]; 2680 w_hash.wh_array[hash] = w; 2681 w_hash.wh_count++; 2682 } 2683 2684 2685 static struct witness_lock_order_data * 2686 witness_lock_order_get(struct witness *parent, struct witness *child) 2687 { 2688 struct witness_lock_order_data *data = NULL; 2689 struct witness_lock_order_key key; 2690 unsigned int hash; 2691 2692 MPASS(parent != NULL && child != NULL); 2693 key.from = parent->w_index; 2694 key.to = child->w_index; 2695 WITNESS_INDEX_ASSERT(key.from); 2696 WITNESS_INDEX_ASSERT(key.to); 2697 if ((w_rmatrix[parent->w_index][child->w_index] 2698 & WITNESS_LOCK_ORDER_KNOWN) == 0) 2699 goto out; 2700 2701 hash = witness_hash_djb2((const char*)&key, 2702 sizeof(key)) % w_lohash.wloh_size; 2703 data = w_lohash.wloh_array[hash]; 2704 while (data != NULL) { 2705 if (witness_lock_order_key_equal(&data->wlod_key, &key)) 2706 break; 2707 data = data->wlod_next; 2708 } 2709 2710 out: 2711 return (data); 2712 } 2713 2714 /* 2715 * Verify that parent and child have a known relationship, are not the same, 2716 * and child is actually a child of parent. This is done without w_mtx 2717 * to avoid contention in the common case. 2718 */ 2719 static int 2720 witness_lock_order_check(struct witness *parent, struct witness *child) 2721 { 2722 2723 if (parent != child && 2724 w_rmatrix[parent->w_index][child->w_index] 2725 & WITNESS_LOCK_ORDER_KNOWN && 2726 isitmychild(parent, child)) 2727 return (1); 2728 2729 return (0); 2730 } 2731 2732 static int 2733 witness_lock_order_add(struct witness *parent, struct witness *child) 2734 { 2735 struct witness_lock_order_data *data = NULL; 2736 struct witness_lock_order_key key; 2737 unsigned int hash; 2738 2739 MPASS(parent != NULL && child != NULL); 2740 key.from = parent->w_index; 2741 key.to = child->w_index; 2742 WITNESS_INDEX_ASSERT(key.from); 2743 WITNESS_INDEX_ASSERT(key.to); 2744 if (w_rmatrix[parent->w_index][child->w_index] 2745 & WITNESS_LOCK_ORDER_KNOWN) 2746 return (1); 2747 2748 hash = witness_hash_djb2((const char*)&key, 2749 sizeof(key)) % w_lohash.wloh_size; 2750 w_rmatrix[parent->w_index][child->w_index] |= WITNESS_LOCK_ORDER_KNOWN; 2751 data = w_lofree; 2752 if (data == NULL) 2753 return (0); 2754 w_lofree = data->wlod_next; 2755 data->wlod_next = w_lohash.wloh_array[hash]; 2756 data->wlod_key = key; 2757 w_lohash.wloh_array[hash] = data; 2758 w_lohash.wloh_count++; 2759 stack_zero(&data->wlod_stack); 2760 stack_save(&data->wlod_stack); 2761 return (1); 2762 } 2763 2764 /* Call this whenver the structure of the witness graph changes. */ 2765 static void 2766 witness_increment_graph_generation(void) 2767 { 2768 2769 if (witness_cold == 0) 2770 mtx_assert(&w_mtx, MA_OWNED); 2771 w_generation++; 2772 } 2773 2774 #ifdef KDB 2775 static void 2776 _witness_debugger(int cond, const char *msg) 2777 { 2778 2779 if (witness_trace && cond) 2780 kdb_backtrace(); 2781 if (witness_kdb && cond) 2782 kdb_enter(KDB_WHY_WITNESS, msg); 2783 } 2784 #endif 2785