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