Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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FreeBSD/Linux Kernel Cross Reference
sys/kern/subr_witness.c
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1 /*- 2 * Copyright (c) 1998 Berkeley Software Design, Inc. All rights reserved. 3 * 4 * Redistribution and use in source and binary forms, with or without 5 * modification, are permitted provided that the following conditions 6 * are met: 7 * 1. Redistributions of source code must retain the above copyright 8 * notice, this list of conditions and the following disclaimer. 9 * 2. Redistributions in binary form must reproduce the above copyright 10 * notice, this list of conditions and the following disclaimer in the 11 * documentation and/or other materials provided with the distribution. 12 * 3. Berkeley Software Design Inc's name may not be used to endorse or 13 * promote products derived from this software without specific prior 14 * written permission. 15 * 16 * THIS SOFTWARE IS PROVIDED BY BERKELEY SOFTWARE DESIGN INC ``AS IS'' AND 17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 19 * ARE DISCLAIMED. IN NO EVENT SHALL BERKELEY SOFTWARE DESIGN INC BE LIABLE 20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26 * SUCH DAMAGE. 27 * 28 * from BSDI $Id: mutex_witness.c,v 1.1.2.20 2000/04/27 03:10:27 cp Exp $ 29 * and BSDI $Id: synch_machdep.c,v 2.3.2.39 2000/04/27 03:10:25 cp Exp $ 30 */ 31 32 /* 33 * Implementation of the `witness' lock verifier. Originally implemented for 34 * mutexes in BSD/OS. Extended to handle generic lock objects and lock 35 * classes in FreeBSD. 36 */ 37 38 /* 39 * Main Entry: witness 40 * Pronunciation: 'wit-n&s 41 * Function: noun 42 * Etymology: Middle English witnesse, from Old English witnes knowledge, 43 * testimony, witness, from 2wit 44 * Date: before 12th century 45 * 1 : attestation of a fact or event : TESTIMONY 46 * 2 : one that gives evidence; specifically : one who testifies in 47 * a cause or before a judicial tribunal 48 * 3 : one asked to be present at a transaction so as to be able to 49 * testify to its having taken place 50 * 4 : one who has personal knowledge of something 51 * 5 a : something serving as evidence or proof : SIGN 52 * b : public affirmation by word or example of usually 53 * religious faith or conviction <the heroic witness to divine 54 * life -- Pilot> 55 * 6 capitalized : a member of the Jehovah's Witnesses 56 */ 57 58 /* 59 * Special rules concerning Giant and lock orders: 60 * 61 * 1) Giant must be acquired before any other mutexes. Stated another way, 62 * no other mutex may be held when Giant is acquired. 63 * 64 * 2) Giant must be released when blocking on a sleepable lock. 65 * 66 * This rule is less obvious, but is a result of Giant providing the same 67 * semantics as spl(). Basically, when a thread sleeps, it must release 68 * Giant. When a thread blocks on a sleepable lock, it sleeps. Hence rule 69 * 2). 70 * 71 * 3) Giant may be acquired before or after sleepable locks. 72 * 73 * This rule is also not quite as obvious. Giant may be acquired after 74 * a sleepable lock because it is a non-sleepable lock and non-sleepable 75 * locks may always be acquired while holding a sleepable lock. The second 76 * case, Giant before a sleepable lock, follows from rule 2) above. Suppose 77 * you have two threads T1 and T2 and a sleepable lock X. Suppose that T1 78 * acquires X and blocks on Giant. Then suppose that T2 acquires Giant and 79 * blocks on X. When T2 blocks on X, T2 will release Giant allowing T1 to 80 * execute. Thus, acquiring Giant both before and after a sleepable lock 81 * will not result in a lock order reversal. 82 */ 83 84 #include <sys/cdefs.h> 85 __FBSDID("$FreeBSD$"); 86 87 #include "opt_ddb.h" 88 #include "opt_witness.h" 89 90 #include <sys/param.h> 91 #include <sys/bus.h> 92 #include <sys/kdb.h> 93 #include <sys/kernel.h> 94 #include <sys/ktr.h> 95 #include <sys/lock.h> 96 #include <sys/malloc.h> 97 #include <sys/mutex.h> 98 #include <sys/proc.h> 99 #include <sys/sysctl.h> 100 #include <sys/systm.h> 101 102 #include <ddb/ddb.h> 103 104 #include <machine/stdarg.h> 105 106 /* Define this to check for blessed mutexes */ 107 #undef BLESSING 108 109 #define WITNESS_COUNT 1024 110 #define WITNESS_CHILDCOUNT (WITNESS_COUNT * 4) 111 /* 112 * XXX: This is somewhat bogus, as we assume here that at most 1024 threads 113 * will hold LOCK_NCHILDREN * 2 locks. We handle failure ok, and we should 114 * probably be safe for the most part, but it's still a SWAG. 115 */ 116 #define LOCK_CHILDCOUNT (MAXCPU + 1024) * 2 117 118 #define WITNESS_NCHILDREN 6 119 120 struct witness_child_list_entry; 121 122 struct witness { 123 const char *w_name; 124 struct lock_class *w_class; 125 STAILQ_ENTRY(witness) w_list; /* List of all witnesses. */ 126 STAILQ_ENTRY(witness) w_typelist; /* Witnesses of a type. */ 127 struct witness_child_list_entry *w_children; /* Great evilness... */ 128 const char *w_file; 129 int w_line; 130 u_int w_level; 131 u_int w_refcount; 132 u_char w_Giant_squawked:1; 133 u_char w_other_squawked:1; 134 u_char w_same_squawked:1; 135 u_char w_displayed:1; 136 }; 137 138 struct witness_child_list_entry { 139 struct witness_child_list_entry *wcl_next; 140 struct witness *wcl_children[WITNESS_NCHILDREN]; 141 u_int wcl_count; 142 }; 143 144 STAILQ_HEAD(witness_list, witness); 145 146 #ifdef BLESSING 147 struct witness_blessed { 148 const char *b_lock1; 149 const char *b_lock2; 150 }; 151 #endif 152 153 struct witness_order_list_entry { 154 const char *w_name; 155 struct lock_class *w_class; 156 }; 157 158 #ifdef BLESSING 159 static int blessed(struct witness *, struct witness *); 160 #endif 161 static int depart(struct witness *w); 162 static struct witness *enroll(const char *description, 163 struct lock_class *lock_class); 164 static int insertchild(struct witness *parent, struct witness *child); 165 static int isitmychild(struct witness *parent, struct witness *child); 166 static int isitmydescendant(struct witness *parent, struct witness *child); 167 static int itismychild(struct witness *parent, struct witness *child); 168 static void removechild(struct witness *parent, struct witness *child); 169 static int sysctl_debug_witness_watch(SYSCTL_HANDLER_ARGS); 170 static const char *fixup_filename(const char *file); 171 static struct witness *witness_get(void); 172 static void witness_free(struct witness *m); 173 static struct witness_child_list_entry *witness_child_get(void); 174 static void witness_child_free(struct witness_child_list_entry *wcl); 175 static struct lock_list_entry *witness_lock_list_get(void); 176 static void witness_lock_list_free(struct lock_list_entry *lle); 177 static struct lock_instance *find_instance(struct lock_list_entry *lock_list, 178 struct lock_object *lock); 179 static void witness_list_lock(struct lock_instance *instance); 180 #ifdef DDB 181 static void witness_leveldescendents(struct witness *parent, int level); 182 static void witness_levelall(void); 183 static void witness_displaydescendants(void(*)(const char *fmt, ...), 184 struct witness *, int indent); 185 static void witness_display_list(void(*prnt)(const char *fmt, ...), 186 struct witness_list *list); 187 static void witness_display(void(*)(const char *fmt, ...)); 188 static void witness_list(struct thread *td); 189 #endif 190 191 SYSCTL_NODE(_debug, OID_AUTO, witness, CTLFLAG_RW, 0, "Witness Locking"); 192 193 /* 194 * If set to 0, witness is disabled. If set to a non-zero value, witness 195 * performs full lock order checking for all locks. At runtime, this 196 * value may be set to 0 to turn off witness. witness is not allowed be 197 * turned on once it is turned off, however. 198 */ 199 static int witness_watch = 1; 200 TUNABLE_INT("debug.witness.watch", &witness_watch); 201 SYSCTL_PROC(_debug_witness, OID_AUTO, watch, CTLFLAG_RW | CTLTYPE_INT, NULL, 0, 202 sysctl_debug_witness_watch, "I", "witness is watching lock operations"); 203 204 #ifdef KDB 205 /* 206 * When KDB is enabled and witness_kdb is set to 1, it will cause the system 207 * to drop into kdebug() when: 208 * - a lock heirarchy violation occurs 209 * - locks are held when going to sleep. 210 */ 211 #ifdef WITNESS_KDB 212 int witness_kdb = 1; 213 #else 214 int witness_kdb = 0; 215 #endif 216 TUNABLE_INT("debug.witness.kdb", &witness_kdb); 217 SYSCTL_INT(_debug_witness, OID_AUTO, kdb, CTLFLAG_RW, &witness_kdb, 0, ""); 218 219 /* 220 * When KDB is enabled and witness_trace is set to 1, it will cause the system 221 * to print a stack trace: 222 * - a lock heirarchy violation occurs 223 * - locks are held when going to sleep. 224 */ 225 int witness_trace = 1; 226 TUNABLE_INT("debug.witness.trace", &witness_trace); 227 SYSCTL_INT(_debug_witness, OID_AUTO, trace, CTLFLAG_RW, &witness_trace, 0, ""); 228 #endif /* KDB */ 229 230 #ifdef WITNESS_SKIPSPIN 231 int witness_skipspin = 1; 232 #else 233 int witness_skipspin = 0; 234 #endif 235 TUNABLE_INT("debug.witness.skipspin", &witness_skipspin); 236 SYSCTL_INT(_debug_witness, OID_AUTO, skipspin, CTLFLAG_RDTUN, 237 &witness_skipspin, 0, ""); 238 239 static struct mtx w_mtx; 240 static struct witness_list w_free = STAILQ_HEAD_INITIALIZER(w_free); 241 static struct witness_list w_all = STAILQ_HEAD_INITIALIZER(w_all); 242 static struct witness_list w_spin = STAILQ_HEAD_INITIALIZER(w_spin); 243 static struct witness_list w_sleep = STAILQ_HEAD_INITIALIZER(w_sleep); 244 static struct witness_child_list_entry *w_child_free = NULL; 245 static struct lock_list_entry *w_lock_list_free = NULL; 246 247 static int w_free_cnt, w_spin_cnt, w_sleep_cnt, w_child_free_cnt, w_child_cnt; 248 SYSCTL_INT(_debug_witness, OID_AUTO, free_cnt, CTLFLAG_RD, &w_free_cnt, 0, ""); 249 SYSCTL_INT(_debug_witness, OID_AUTO, spin_cnt, CTLFLAG_RD, &w_spin_cnt, 0, ""); 250 SYSCTL_INT(_debug_witness, OID_AUTO, sleep_cnt, CTLFLAG_RD, &w_sleep_cnt, 0, 251 ""); 252 SYSCTL_INT(_debug_witness, OID_AUTO, child_free_cnt, CTLFLAG_RD, 253 &w_child_free_cnt, 0, ""); 254 SYSCTL_INT(_debug_witness, OID_AUTO, child_cnt, CTLFLAG_RD, &w_child_cnt, 0, 255 ""); 256 257 static struct witness w_data[WITNESS_COUNT]; 258 static struct witness_child_list_entry w_childdata[WITNESS_CHILDCOUNT]; 259 static struct lock_list_entry w_locklistdata[LOCK_CHILDCOUNT]; 260 261 static struct witness_order_list_entry order_lists[] = { 262 /* 263 * sx locks 264 */ 265 { "proctree", &lock_class_sx }, 266 { "allproc", &lock_class_sx }, 267 { NULL, NULL }, 268 /* 269 * Various mutexes 270 */ 271 { "Giant", &lock_class_mtx_sleep }, 272 { "filedesc structure", &lock_class_mtx_sleep }, 273 { "pipe mutex", &lock_class_mtx_sleep }, 274 { "sigio lock", &lock_class_mtx_sleep }, 275 { "process group", &lock_class_mtx_sleep }, 276 { "process lock", &lock_class_mtx_sleep }, 277 { "session", &lock_class_mtx_sleep }, 278 { "uidinfo hash", &lock_class_mtx_sleep }, 279 { "uidinfo struct", &lock_class_mtx_sleep }, 280 { "allprison", &lock_class_mtx_sleep }, 281 { NULL, NULL }, 282 /* 283 * Sockets 284 */ 285 { "filedesc structure", &lock_class_mtx_sleep }, 286 { "accept", &lock_class_mtx_sleep }, 287 { "so_snd", &lock_class_mtx_sleep }, 288 { "so_rcv", &lock_class_mtx_sleep }, 289 { "sellck", &lock_class_mtx_sleep }, 290 { NULL, NULL }, 291 /* 292 * Routing 293 */ 294 { "so_rcv", &lock_class_mtx_sleep }, 295 { "radix node head", &lock_class_mtx_sleep }, 296 { "rtentry", &lock_class_mtx_sleep }, 297 { "ifaddr", &lock_class_mtx_sleep }, 298 { NULL, NULL }, 299 /* 300 * Multicast - protocol locks before interface locks. 301 */ 302 { "in_multi_mtx", &lock_class_mtx_sleep }, 303 { "igmp_mtx", &lock_class_mtx_sleep }, 304 { "if_addr_mtx", &lock_class_mtx_sleep }, 305 { NULL, NULL }, 306 /* 307 * UNIX Domain Sockets 308 */ 309 { "unp", &lock_class_mtx_sleep }, 310 { "so_snd", &lock_class_mtx_sleep }, 311 { NULL, NULL }, 312 /* 313 * UDP/IP 314 */ 315 { "udp", &lock_class_mtx_sleep }, 316 { "udpinp", &lock_class_mtx_sleep }, 317 { "so_snd", &lock_class_mtx_sleep }, 318 { NULL, NULL }, 319 /* 320 * TCP/IP 321 */ 322 { "tcp", &lock_class_mtx_sleep }, 323 { "tcpinp", &lock_class_mtx_sleep }, 324 { "so_snd", &lock_class_mtx_sleep }, 325 { NULL, NULL }, 326 /* 327 * SLIP 328 */ 329 { "slip_mtx", &lock_class_mtx_sleep }, 330 { "slip sc_mtx", &lock_class_mtx_sleep }, 331 { NULL, NULL }, 332 /* 333 * netatalk 334 */ 335 { "ddp_list_mtx", &lock_class_mtx_sleep }, 336 { "ddp_mtx", &lock_class_mtx_sleep }, 337 { NULL, NULL }, 338 /* 339 * BPF 340 */ 341 { "bpf global lock", &lock_class_mtx_sleep }, 342 { "bpf interface lock", &lock_class_mtx_sleep }, 343 { "bpf cdev lock", &lock_class_mtx_sleep }, 344 { NULL, NULL }, 345 /* 346 * NFS server 347 */ 348 { "nfsd_mtx", &lock_class_mtx_sleep }, 349 { "so_snd", &lock_class_mtx_sleep }, 350 { NULL, NULL }, 351 /* 352 * Netgraph 353 */ 354 { "ng_node", &lock_class_mtx_sleep }, 355 { "ng_worklist", &lock_class_mtx_sleep }, 356 { NULL, NULL }, 357 /* 358 * CDEV 359 */ 360 { "system map", &lock_class_mtx_sleep }, 361 { "vm page queue mutex", &lock_class_mtx_sleep }, 362 { "vnode interlock", &lock_class_mtx_sleep }, 363 { "cdev", &lock_class_mtx_sleep }, 364 { NULL, NULL }, 365 /* 366 * spin locks 367 */ 368 #ifdef SMP 369 { "ap boot", &lock_class_mtx_spin }, 370 #endif 371 { "rm.mutex_mtx", &lock_class_mtx_spin }, 372 { "sio", &lock_class_mtx_spin }, 373 #ifdef __i386__ 374 { "cy", &lock_class_mtx_spin }, 375 #endif 376 { "uart_hwmtx", &lock_class_mtx_spin }, 377 { "sabtty", &lock_class_mtx_spin }, 378 { "zstty", &lock_class_mtx_spin }, 379 { "fast_taskqueue", &lock_class_mtx_spin }, 380 { "intr table", &lock_class_mtx_spin }, 381 { "sleepq chain", &lock_class_mtx_spin }, 382 { "sched lock", &lock_class_mtx_spin }, 383 { "turnstile chain", &lock_class_mtx_spin }, 384 { "td_contested", &lock_class_mtx_spin }, 385 { "callout", &lock_class_mtx_spin }, 386 { "entropy harvest mutex", &lock_class_mtx_spin }, 387 /* 388 * leaf locks 389 */ 390 { "allpmaps", &lock_class_mtx_spin }, 391 { "vm page queue free mutex", &lock_class_mtx_spin }, 392 { "icu", &lock_class_mtx_spin }, 393 #ifdef SMP 394 { "smp rendezvous", &lock_class_mtx_spin }, 395 #if defined(__i386__) || defined(__amd64__) 396 { "tlb", &lock_class_mtx_spin }, 397 #endif 398 #ifdef __sparc64__ 399 { "ipi", &lock_class_mtx_spin }, 400 { "rtc_mtx", &lock_class_mtx_spin }, 401 #endif 402 #endif 403 { "clk", &lock_class_mtx_spin }, 404 { "mutex profiling lock", &lock_class_mtx_spin }, 405 { "kse zombie lock", &lock_class_mtx_spin }, 406 { "ALD Queue", &lock_class_mtx_spin }, 407 #ifdef __ia64__ 408 { "MCA spin lock", &lock_class_mtx_spin }, 409 #endif 410 #if defined(__i386__) || defined(__amd64__) 411 { "pcicfg", &lock_class_mtx_spin }, 412 { "NDIS thread lock", &lock_class_mtx_spin }, 413 #endif 414 { "tw_osl_io_lock", &lock_class_mtx_spin }, 415 { "tw_osl_q_lock", &lock_class_mtx_spin }, 416 { "tw_cl_io_lock", &lock_class_mtx_spin }, 417 { "tw_cl_intr_lock", &lock_class_mtx_spin }, 418 { "tw_cl_gen_lock", &lock_class_mtx_spin }, 419 { NULL, NULL }, 420 { NULL, NULL } 421 }; 422 423 #ifdef BLESSING 424 /* 425 * Pairs of locks which have been blessed 426 * Don't complain about order problems with blessed locks 427 */ 428 static struct witness_blessed blessed_list[] = { 429 }; 430 static int blessed_count = 431 sizeof(blessed_list) / sizeof(struct witness_blessed); 432 #endif 433 434 /* 435 * List of all locks in the system. 436 */ 437 TAILQ_HEAD(, lock_object) all_locks = TAILQ_HEAD_INITIALIZER(all_locks); 438 439 static struct mtx all_mtx = { 440 { &lock_class_mtx_sleep, /* mtx_object.lo_class */ 441 "All locks list", /* mtx_object.lo_name */ 442 "All locks list", /* mtx_object.lo_type */ 443 LO_INITIALIZED, /* mtx_object.lo_flags */ 444 { NULL, NULL }, /* mtx_object.lo_list */ 445 NULL }, /* mtx_object.lo_witness */ 446 MTX_UNOWNED, 0 /* mtx_lock, mtx_recurse */ 447 }; 448 449 /* 450 * This global is set to 0 once it becomes safe to use the witness code. 451 */ 452 static int witness_cold = 1; 453 454 /* 455 * This global is set to 1 once the static lock orders have been enrolled 456 * so that a warning can be issued for any spin locks enrolled later. 457 */ 458 static int witness_spin_warn = 0; 459 460 /* 461 * Global variables for book keeping. 462 */ 463 static int lock_cur_cnt; 464 static int lock_max_cnt; 465 466 /* 467 * The WITNESS-enabled diagnostic code. 468 */ 469 static void 470 witness_initialize(void *dummy __unused) 471 { 472 struct lock_object *lock; 473 struct witness_order_list_entry *order; 474 struct witness *w, *w1; 475 int i; 476 477 /* 478 * We have to release Giant before initializing its witness 479 * structure so that WITNESS doesn't get confused. 480 */ 481 mtx_unlock(&Giant); 482 mtx_assert(&Giant, MA_NOTOWNED); 483 484 CTR1(KTR_WITNESS, "%s: initializing witness", __func__); 485 TAILQ_INSERT_HEAD(&all_locks, &all_mtx.mtx_object, lo_list); 486 mtx_init(&w_mtx, "witness lock", NULL, MTX_SPIN | MTX_QUIET | 487 MTX_NOWITNESS); 488 for (i = 0; i < WITNESS_COUNT; i++) 489 witness_free(&w_data[i]); 490 for (i = 0; i < WITNESS_CHILDCOUNT; i++) 491 witness_child_free(&w_childdata[i]); 492 for (i = 0; i < LOCK_CHILDCOUNT; i++) 493 witness_lock_list_free(&w_locklistdata[i]); 494 495 /* First add in all the specified order lists. */ 496 for (order = order_lists; order->w_name != NULL; order++) { 497 w = enroll(order->w_name, order->w_class); 498 if (w == NULL) 499 continue; 500 w->w_file = "order list"; 501 for (order++; order->w_name != NULL; order++) { 502 w1 = enroll(order->w_name, order->w_class); 503 if (w1 == NULL) 504 continue; 505 w1->w_file = "order list"; 506 if (!itismychild(w, w1)) 507 panic("Not enough memory for static orders!"); 508 w = w1; 509 } 510 } 511 witness_spin_warn = 1; 512 513 /* Iterate through all locks and add them to witness. */ 514 mtx_lock(&all_mtx); 515 TAILQ_FOREACH(lock, &all_locks, lo_list) { 516 if (lock->lo_flags & LO_WITNESS) 517 lock->lo_witness = enroll(lock->lo_type, 518 LOCK_CLASS(lock)); 519 else 520 lock->lo_witness = NULL; 521 } 522 mtx_unlock(&all_mtx); 523 524 /* Mark the witness code as being ready for use. */ 525 witness_cold = 0; 526 527 mtx_lock(&Giant); 528 } 529 SYSINIT(witness_init, SI_SUB_WITNESS, SI_ORDER_FIRST, witness_initialize, NULL) 530 531 static int 532 sysctl_debug_witness_watch(SYSCTL_HANDLER_ARGS) 533 { 534 int error, value; 535 536 value = witness_watch; 537 error = sysctl_handle_int(oidp, &value, 0, req); 538 if (error != 0 || req->newptr == NULL) 539 return (error); 540 error = suser(req->td); 541 if (error != 0) 542 return (error); 543 if (value == witness_watch) 544 return (0); 545 if (value != 0) 546 return (EINVAL); 547 witness_watch = 0; 548 return (0); 549 } 550 551 void 552 witness_init(struct lock_object *lock) 553 { 554 struct lock_class *class; 555 556 class = LOCK_CLASS(lock); 557 if ((lock->lo_flags & LO_RECURSABLE) != 0 && 558 (class->lc_flags & LC_RECURSABLE) == 0) 559 panic("%s: lock (%s) %s can not be recursable", __func__, 560 class->lc_name, lock->lo_name); 561 if ((lock->lo_flags & LO_SLEEPABLE) != 0 && 562 (class->lc_flags & LC_SLEEPABLE) == 0) 563 panic("%s: lock (%s) %s can not be sleepable", __func__, 564 class->lc_name, lock->lo_name); 565 if ((lock->lo_flags & LO_UPGRADABLE) != 0 && 566 (class->lc_flags & LC_UPGRADABLE) == 0) 567 panic("%s: lock (%s) %s can not be upgradable", __func__, 568 class->lc_name, lock->lo_name); 569 570 mtx_lock(&all_mtx); 571 TAILQ_INSERT_TAIL(&all_locks, lock, lo_list); 572 lock_cur_cnt++; 573 if (lock_cur_cnt > lock_max_cnt) 574 lock_max_cnt = lock_cur_cnt; 575 mtx_unlock(&all_mtx); 576 if (!witness_cold && witness_watch != 0 && panicstr == NULL && 577 (lock->lo_flags & LO_WITNESS) != 0) 578 lock->lo_witness = enroll(lock->lo_type, class); 579 else 580 lock->lo_witness = NULL; 581 } 582 583 void 584 witness_destroy(struct lock_object *lock) 585 { 586 struct lock_class *class; 587 struct witness *w; 588 589 class = LOCK_CLASS(lock); 590 if (witness_cold) 591 panic("lock (%s) %s destroyed while witness_cold", 592 class->lc_name, lock->lo_name); 593 594 /* XXX: need to verify that no one holds the lock */ 595 w = lock->lo_witness; 596 if (w != NULL) { 597 mtx_lock_spin(&w_mtx); 598 MPASS(w->w_refcount > 0); 599 w->w_refcount--; 600 601 /* 602 * Lock is already released if we have an allocation failure 603 * and depart() fails. 604 */ 605 if (w->w_refcount != 0 || depart(w)) 606 mtx_unlock_spin(&w_mtx); 607 } 608 609 mtx_lock(&all_mtx); 610 lock_cur_cnt--; 611 TAILQ_REMOVE(&all_locks, lock, lo_list); 612 mtx_unlock(&all_mtx); 613 } 614 615 #ifdef DDB 616 static void 617 witness_levelall (void) 618 { 619 struct witness_list *list; 620 struct witness *w, *w1; 621 622 /* 623 * First clear all levels. 624 */ 625 STAILQ_FOREACH(w, &w_all, w_list) { 626 w->w_level = 0; 627 } 628 629 /* 630 * Look for locks with no parent and level all their descendants. 631 */ 632 STAILQ_FOREACH(w, &w_all, w_list) { 633 /* 634 * This is just an optimization, technically we could get 635 * away just walking the all list each time. 636 */ 637 if (w->w_class->lc_flags & LC_SLEEPLOCK) 638 list = &w_sleep; 639 else 640 list = &w_spin; 641 STAILQ_FOREACH(w1, list, w_typelist) { 642 if (isitmychild(w1, w)) 643 goto skip; 644 } 645 witness_leveldescendents(w, 0); 646 skip: 647 ; /* silence GCC 3.x */ 648 } 649 } 650 651 static void 652 witness_leveldescendents(struct witness *parent, int level) 653 { 654 struct witness_child_list_entry *wcl; 655 int i; 656 657 if (parent->w_level < level) 658 parent->w_level = level; 659 level++; 660 for (wcl = parent->w_children; wcl != NULL; wcl = wcl->wcl_next) 661 for (i = 0; i < wcl->wcl_count; i++) 662 witness_leveldescendents(wcl->wcl_children[i], level); 663 } 664 665 static void 666 witness_displaydescendants(void(*prnt)(const char *fmt, ...), 667 struct witness *parent, int indent) 668 { 669 struct witness_child_list_entry *wcl; 670 int i, level; 671 672 level = parent->w_level; 673 prnt("%-2d", level); 674 for (i = 0; i < indent; i++) 675 prnt(" "); 676 if (parent->w_refcount > 0) 677 prnt("%s", parent->w_name); 678 else 679 prnt("(dead)"); 680 if (parent->w_displayed) { 681 prnt(" -- (already displayed)\n"); 682 return; 683 } 684 parent->w_displayed = 1; 685 if (parent->w_refcount > 0) { 686 if (parent->w_file != NULL) 687 prnt(" -- last acquired @ %s:%d", parent->w_file, 688 parent->w_line); 689 } 690 prnt("\n"); 691 for (wcl = parent->w_children; wcl != NULL; wcl = wcl->wcl_next) 692 for (i = 0; i < wcl->wcl_count; i++) 693 witness_displaydescendants(prnt, 694 wcl->wcl_children[i], indent + 1); 695 } 696 697 static void 698 witness_display_list(void(*prnt)(const char *fmt, ...), 699 struct witness_list *list) 700 { 701 struct witness *w; 702 703 STAILQ_FOREACH(w, list, w_typelist) { 704 if (w->w_file == NULL || w->w_level > 0) 705 continue; 706 /* 707 * This lock has no anscestors, display its descendants. 708 */ 709 witness_displaydescendants(prnt, w, 0); 710 } 711 } 712 713 static void 714 witness_display(void(*prnt)(const char *fmt, ...)) 715 { 716 struct witness *w; 717 718 KASSERT(!witness_cold, ("%s: witness_cold", __func__)); 719 witness_levelall(); 720 721 /* Clear all the displayed flags. */ 722 STAILQ_FOREACH(w, &w_all, w_list) { 723 w->w_displayed = 0; 724 } 725 726 /* 727 * First, handle sleep locks which have been acquired at least 728 * once. 729 */ 730 prnt("Sleep locks:\n"); 731 witness_display_list(prnt, &w_sleep); 732 733 /* 734 * Now do spin locks which have been acquired at least once. 735 */ 736 prnt("\nSpin locks:\n"); 737 witness_display_list(prnt, &w_spin); 738 739 /* 740 * Finally, any locks which have not been acquired yet. 741 */ 742 prnt("\nLocks which were never acquired:\n"); 743 STAILQ_FOREACH(w, &w_all, w_list) { 744 if (w->w_file != NULL || w->w_refcount == 0) 745 continue; 746 prnt("%s\n", w->w_name); 747 } 748 } 749 #endif /* DDB */ 750 751 /* Trim useless garbage from filenames. */ 752 static const char * 753 fixup_filename(const char *file) 754 { 755 756 if (file == NULL) 757 return (NULL); 758 while (strncmp(file, "../", 3) == 0) 759 file += 3; 760 return (file); 761 } 762 763 int 764 witness_defineorder(struct lock_object *lock1, struct lock_object *lock2) 765 { 766 767 if (witness_watch == 0 || panicstr != NULL) 768 return (0); 769 770 /* Require locks that witness knows about. */ 771 if (lock1 == NULL || lock1->lo_witness == NULL || lock2 == NULL || 772 lock2->lo_witness == NULL) 773 return (EINVAL); 774 775 MPASS(!mtx_owned(&w_mtx)); 776 mtx_lock_spin(&w_mtx); 777 778 /* 779 * If we already have either an explicit or implied lock order that 780 * is the other way around, then return an error. 781 */ 782 if (isitmydescendant(lock2->lo_witness, lock1->lo_witness)) { 783 mtx_unlock_spin(&w_mtx); 784 return (EDOOFUS); 785 } 786 787 /* Try to add the new order. */ 788 CTR3(KTR_WITNESS, "%s: adding %s as a child of %s", __func__, 789 lock2->lo_type, lock1->lo_type); 790 if (!itismychild(lock1->lo_witness, lock2->lo_witness)) 791 return (ENOMEM); 792 mtx_unlock_spin(&w_mtx); 793 return (0); 794 } 795 796 void 797 witness_checkorder(struct lock_object *lock, int flags, const char *file, 798 int line) 799 { 800 struct lock_list_entry **lock_list, *lle; 801 struct lock_instance *lock1, *lock2; 802 struct lock_class *class; 803 struct witness *w, *w1; 804 struct thread *td; 805 int i, j; 806 807 if (witness_cold || witness_watch == 0 || lock->lo_witness == NULL || 808 panicstr != NULL) 809 return; 810 811 /* 812 * Try locks do not block if they fail to acquire the lock, thus 813 * there is no danger of deadlocks or of switching while holding a 814 * spin lock if we acquire a lock via a try operation. This 815 * function shouldn't even be called for try locks, so panic if 816 * that happens. 817 */ 818 if (flags & LOP_TRYLOCK) 819 panic("%s should not be called for try lock operations", 820 __func__); 821 822 w = lock->lo_witness; 823 class = LOCK_CLASS(lock); 824 td = curthread; 825 file = fixup_filename(file); 826 827 if (class->lc_flags & LC_SLEEPLOCK) { 828 /* 829 * Since spin locks include a critical section, this check 830 * implicitly enforces a lock order of all sleep locks before 831 * all spin locks. 832 */ 833 if (td->td_critnest != 0 && !kdb_active) 834 panic("blockable sleep lock (%s) %s @ %s:%d", 835 class->lc_name, lock->lo_name, file, line); 836 837 /* 838 * If this is the first lock acquired then just return as 839 * no order checking is needed. 840 */ 841 if (td->td_sleeplocks == NULL) 842 return; 843 lock_list = &td->td_sleeplocks; 844 } else { 845 /* 846 * If this is the first lock, just return as no order 847 * checking is needed. We check this in both if clauses 848 * here as unifying the check would require us to use a 849 * critical section to ensure we don't migrate while doing 850 * the check. Note that if this is not the first lock, we 851 * are already in a critical section and are safe for the 852 * rest of the check. 853 */ 854 if (PCPU_GET(spinlocks) == NULL) 855 return; 856 lock_list = PCPU_PTR(spinlocks); 857 } 858 859 /* 860 * Check to see if we are recursing on a lock we already own. If 861 * so, make sure that we don't mismatch exclusive and shared lock 862 * acquires. 863 */ 864 lock1 = find_instance(*lock_list, lock); 865 if (lock1 != NULL) { 866 if ((lock1->li_flags & LI_EXCLUSIVE) != 0 && 867 (flags & LOP_EXCLUSIVE) == 0) { 868 printf("shared lock of (%s) %s @ %s:%d\n", 869 class->lc_name, lock->lo_name, file, line); 870 printf("while exclusively locked from %s:%d\n", 871 lock1->li_file, lock1->li_line); 872 panic("share->excl"); 873 } 874 if ((lock1->li_flags & LI_EXCLUSIVE) == 0 && 875 (flags & LOP_EXCLUSIVE) != 0) { 876 printf("exclusive lock of (%s) %s @ %s:%d\n", 877 class->lc_name, lock->lo_name, file, line); 878 printf("while share locked from %s:%d\n", 879 lock1->li_file, lock1->li_line); 880 panic("excl->share"); 881 } 882 return; 883 } 884 885 /* 886 * Try locks do not block if they fail to acquire the lock, thus 887 * there is no danger of deadlocks or of switching while holding a 888 * spin lock if we acquire a lock via a try operation. 889 */ 890 if (flags & LOP_TRYLOCK) 891 return; 892 893 /* 894 * Check for duplicate locks of the same type. Note that we only 895 * have to check for this on the last lock we just acquired. Any 896 * other cases will be caught as lock order violations. 897 */ 898 lock1 = &(*lock_list)->ll_children[(*lock_list)->ll_count - 1]; 899 w1 = lock1->li_lock->lo_witness; 900 if (w1 == w) { 901 if (w->w_same_squawked || (lock->lo_flags & LO_DUPOK) || 902 (flags & LOP_DUPOK)) 903 return; 904 w->w_same_squawked = 1; 905 printf("acquiring duplicate lock of same type: \"%s\"\n", 906 lock->lo_type); 907 printf(" 1st %s @ %s:%d\n", lock1->li_lock->lo_name, 908 lock1->li_file, lock1->li_line); 909 printf(" 2nd %s @ %s:%d\n", lock->lo_name, file, line); 910 #ifdef KDB 911 goto debugger; 912 #else 913 return; 914 #endif 915 } 916 MPASS(!mtx_owned(&w_mtx)); 917 mtx_lock_spin(&w_mtx); 918 /* 919 * If we know that the the lock we are acquiring comes after 920 * the lock we most recently acquired in the lock order tree, 921 * then there is no need for any further checks. 922 */ 923 if (isitmychild(w1, w)) { 924 mtx_unlock_spin(&w_mtx); 925 return; 926 } 927 for (j = 0, lle = *lock_list; lle != NULL; lle = lle->ll_next) { 928 for (i = lle->ll_count - 1; i >= 0; i--, j++) { 929 930 MPASS(j < WITNESS_COUNT); 931 lock1 = &lle->ll_children[i]; 932 w1 = lock1->li_lock->lo_witness; 933 934 /* 935 * If this lock doesn't undergo witness checking, 936 * then skip it. 937 */ 938 if (w1 == NULL) { 939 KASSERT((lock1->li_lock->lo_flags & LO_WITNESS) == 0, 940 ("lock missing witness structure")); 941 continue; 942 } 943 /* 944 * If we are locking Giant and this is a sleepable 945 * lock, then skip it. 946 */ 947 if ((lock1->li_lock->lo_flags & LO_SLEEPABLE) != 0 && 948 lock == &Giant.mtx_object) 949 continue; 950 /* 951 * If we are locking a sleepable lock and this lock 952 * is Giant, then skip it. 953 */ 954 if ((lock->lo_flags & LO_SLEEPABLE) != 0 && 955 lock1->li_lock == &Giant.mtx_object) 956 continue; 957 /* 958 * If we are locking a sleepable lock and this lock 959 * isn't sleepable, we want to treat it as a lock 960 * order violation to enfore a general lock order of 961 * sleepable locks before non-sleepable locks. 962 */ 963 if (((lock->lo_flags & LO_SLEEPABLE) != 0 && 964 (lock1->li_lock->lo_flags & LO_SLEEPABLE) == 0)) 965 goto reversal; 966 /* 967 * If we are locking Giant and this is a non-sleepable 968 * lock, then treat it as a reversal. 969 */ 970 if ((lock1->li_lock->lo_flags & LO_SLEEPABLE) == 0 && 971 lock == &Giant.mtx_object) 972 goto reversal; 973 /* 974 * Check the lock order hierarchy for a reveresal. 975 */ 976 if (!isitmydescendant(w, w1)) 977 continue; 978 reversal: 979 /* 980 * We have a lock order violation, check to see if it 981 * is allowed or has already been yelled about. 982 */ 983 mtx_unlock_spin(&w_mtx); 984 #ifdef BLESSING 985 /* 986 * If the lock order is blessed, just bail. We don't 987 * look for other lock order violations though, which 988 * may be a bug. 989 */ 990 if (blessed(w, w1)) 991 return; 992 #endif 993 if (lock1->li_lock == &Giant.mtx_object) { 994 if (w1->w_Giant_squawked) 995 return; 996 else 997 w1->w_Giant_squawked = 1; 998 } else { 999 if (w1->w_other_squawked) 1000 return; 1001 else 1002 w1->w_other_squawked = 1; 1003 } 1004 /* 1005 * Ok, yell about it. 1006 */ 1007 if (((lock->lo_flags & LO_SLEEPABLE) != 0 && 1008 (lock1->li_lock->lo_flags & LO_SLEEPABLE) == 0)) 1009 printf( 1010 "lock order reversal: (sleepable after non-sleepable)\n"); 1011 else if ((lock1->li_lock->lo_flags & LO_SLEEPABLE) == 0 1012 && lock == &Giant.mtx_object) 1013 printf( 1014 "lock order reversal: (Giant after non-sleepable)\n"); 1015 else 1016 printf("lock order reversal:\n"); 1017 /* 1018 * Try to locate an earlier lock with 1019 * witness w in our list. 1020 */ 1021 do { 1022 lock2 = &lle->ll_children[i]; 1023 MPASS(lock2->li_lock != NULL); 1024 if (lock2->li_lock->lo_witness == w) 1025 break; 1026 if (i == 0 && lle->ll_next != NULL) { 1027 lle = lle->ll_next; 1028 i = lle->ll_count - 1; 1029 MPASS(i >= 0 && i < LOCK_NCHILDREN); 1030 } else 1031 i--; 1032 } while (i >= 0); 1033 if (i < 0) { 1034 printf(" 1st %p %s (%s) @ %s:%d\n", 1035 lock1->li_lock, lock1->li_lock->lo_name, 1036 lock1->li_lock->lo_type, lock1->li_file, 1037 lock1->li_line); 1038 printf(" 2nd %p %s (%s) @ %s:%d\n", lock, 1039 lock->lo_name, lock->lo_type, file, line); 1040 } else { 1041 printf(" 1st %p %s (%s) @ %s:%d\n", 1042 lock2->li_lock, lock2->li_lock->lo_name, 1043 lock2->li_lock->lo_type, lock2->li_file, 1044 lock2->li_line); 1045 printf(" 2nd %p %s (%s) @ %s:%d\n", 1046 lock1->li_lock, lock1->li_lock->lo_name, 1047 lock1->li_lock->lo_type, lock1->li_file, 1048 lock1->li_line); 1049 printf(" 3rd %p %s (%s) @ %s:%d\n", lock, 1050 lock->lo_name, lock->lo_type, file, line); 1051 } 1052 #ifdef KDB 1053 goto debugger; 1054 #else 1055 return; 1056 #endif 1057 } 1058 } 1059 lock1 = &(*lock_list)->ll_children[(*lock_list)->ll_count - 1]; 1060 /* 1061 * If requested, build a new lock order. However, don't build a new 1062 * relationship between a sleepable lock and Giant if it is in the 1063 * wrong direction. The correct lock order is that sleepable locks 1064 * always come before Giant. 1065 */ 1066 if (flags & LOP_NEWORDER && 1067 !(lock1->li_lock == &Giant.mtx_object && 1068 (lock->lo_flags & LO_SLEEPABLE) != 0)) { 1069 CTR3(KTR_WITNESS, "%s: adding %s as a child of %s", __func__, 1070 lock->lo_type, lock1->li_lock->lo_type); 1071 if (!itismychild(lock1->li_lock->lo_witness, w)) 1072 /* Witness is dead. */ 1073 return; 1074 } 1075 mtx_unlock_spin(&w_mtx); 1076 return; 1077 1078 #ifdef KDB 1079 debugger: 1080 if (witness_trace) 1081 kdb_backtrace(); 1082 if (witness_kdb) 1083 kdb_enter(__func__); 1084 #endif 1085 } 1086 1087 void 1088 witness_lock(struct lock_object *lock, int flags, const char *file, int line) 1089 { 1090 struct lock_list_entry **lock_list, *lle; 1091 struct lock_instance *instance; 1092 struct witness *w; 1093 struct thread *td; 1094 1095 if (witness_cold || witness_watch == 0 || lock->lo_witness == NULL || 1096 panicstr != NULL) 1097 return; 1098 w = lock->lo_witness; 1099 td = curthread; 1100 file = fixup_filename(file); 1101 1102 /* Determine lock list for this lock. */ 1103 if (LOCK_CLASS(lock)->lc_flags & LC_SLEEPLOCK) 1104 lock_list = &td->td_sleeplocks; 1105 else 1106 lock_list = PCPU_PTR(spinlocks); 1107 1108 /* Check to see if we are recursing on a lock we already own. */ 1109 instance = find_instance(*lock_list, lock); 1110 if (instance != NULL) { 1111 instance->li_flags++; 1112 CTR4(KTR_WITNESS, "%s: pid %d recursed on %s r=%d", __func__, 1113 td->td_proc->p_pid, lock->lo_name, 1114 instance->li_flags & LI_RECURSEMASK); 1115 instance->li_file = file; 1116 instance->li_line = line; 1117 return; 1118 } 1119 1120 /* Update per-witness last file and line acquire. */ 1121 w->w_file = file; 1122 w->w_line = line; 1123 1124 /* Find the next open lock instance in the list and fill it. */ 1125 lle = *lock_list; 1126 if (lle == NULL || lle->ll_count == LOCK_NCHILDREN) { 1127 lle = witness_lock_list_get(); 1128 if (lle == NULL) 1129 return; 1130 lle->ll_next = *lock_list; 1131 CTR3(KTR_WITNESS, "%s: pid %d added lle %p", __func__, 1132 td->td_proc->p_pid, lle); 1133 *lock_list = lle; 1134 } 1135 instance = &lle->ll_children[lle->ll_count++]; 1136 instance->li_lock = lock; 1137 instance->li_line = line; 1138 instance->li_file = file; 1139 if ((flags & LOP_EXCLUSIVE) != 0) 1140 instance->li_flags = LI_EXCLUSIVE; 1141 else 1142 instance->li_flags = 0; 1143 CTR4(KTR_WITNESS, "%s: pid %d added %s as lle[%d]", __func__, 1144 td->td_proc->p_pid, lock->lo_name, lle->ll_count - 1); 1145 } 1146 1147 void 1148 witness_upgrade(struct lock_object *lock, int flags, const char *file, int line) 1149 { 1150 struct lock_instance *instance; 1151 struct lock_class *class; 1152 1153 KASSERT(!witness_cold, ("%s: witness_cold", __func__)); 1154 if (lock->lo_witness == NULL || witness_watch == 0 || panicstr != NULL) 1155 return; 1156 class = LOCK_CLASS(lock); 1157 file = fixup_filename(file); 1158 if ((lock->lo_flags & LO_UPGRADABLE) == 0) 1159 panic("upgrade of non-upgradable lock (%s) %s @ %s:%d", 1160 class->lc_name, lock->lo_name, file, line); 1161 if ((flags & LOP_TRYLOCK) == 0) 1162 panic("non-try upgrade of lock (%s) %s @ %s:%d", class->lc_name, 1163 lock->lo_name, file, line); 1164 if ((class->lc_flags & LC_SLEEPLOCK) == 0) 1165 panic("upgrade of non-sleep lock (%s) %s @ %s:%d", 1166 class->lc_name, lock->lo_name, file, line); 1167 instance = find_instance(curthread->td_sleeplocks, lock); 1168 if (instance == NULL) 1169 panic("upgrade of unlocked lock (%s) %s @ %s:%d", 1170 class->lc_name, lock->lo_name, file, line); 1171 if ((instance->li_flags & LI_EXCLUSIVE) != 0) 1172 panic("upgrade of exclusive lock (%s) %s @ %s:%d", 1173 class->lc_name, lock->lo_name, file, line); 1174 if ((instance->li_flags & LI_RECURSEMASK) != 0) 1175 panic("upgrade of recursed lock (%s) %s r=%d @ %s:%d", 1176 class->lc_name, lock->lo_name, 1177 instance->li_flags & LI_RECURSEMASK, file, line); 1178 instance->li_flags |= LI_EXCLUSIVE; 1179 } 1180 1181 void 1182 witness_downgrade(struct lock_object *lock, int flags, const char *file, 1183 int line) 1184 { 1185 struct lock_instance *instance; 1186 struct lock_class *class; 1187 1188 KASSERT(!witness_cold, ("%s: witness_cold", __func__)); 1189 if (lock->lo_witness == NULL || witness_watch == 0 || panicstr != NULL) 1190 return; 1191 class = LOCK_CLASS(lock); 1192 file = fixup_filename(file); 1193 if ((lock->lo_flags & LO_UPGRADABLE) == 0) 1194 panic("downgrade of non-upgradable lock (%s) %s @ %s:%d", 1195 class->lc_name, lock->lo_name, file, line); 1196 if ((class->lc_flags & LC_SLEEPLOCK) == 0) 1197 panic("downgrade of non-sleep lock (%s) %s @ %s:%d", 1198 class->lc_name, lock->lo_name, file, line); 1199 instance = find_instance(curthread->td_sleeplocks, lock); 1200 if (instance == NULL) 1201 panic("downgrade of unlocked lock (%s) %s @ %s:%d", 1202 class->lc_name, lock->lo_name, file, line); 1203 if ((instance->li_flags & LI_EXCLUSIVE) == 0) 1204 panic("downgrade of shared lock (%s) %s @ %s:%d", 1205 class->lc_name, lock->lo_name, file, line); 1206 if ((instance->li_flags & LI_RECURSEMASK) != 0) 1207 panic("downgrade of recursed lock (%s) %s r=%d @ %s:%d", 1208 class->lc_name, lock->lo_name, 1209 instance->li_flags & LI_RECURSEMASK, file, line); 1210 instance->li_flags &= ~LI_EXCLUSIVE; 1211 } 1212 1213 void 1214 witness_unlock(struct lock_object *lock, int flags, const char *file, int line) 1215 { 1216 struct lock_list_entry **lock_list, *lle; 1217 struct lock_instance *instance; 1218 struct lock_class *class; 1219 struct thread *td; 1220 register_t s; 1221 int i, j; 1222 1223 if (witness_cold || witness_watch == 0 || lock->lo_witness == NULL || 1224 panicstr != NULL) 1225 return; 1226 td = curthread; 1227 class = LOCK_CLASS(lock); 1228 file = fixup_filename(file); 1229 1230 /* Find lock instance associated with this lock. */ 1231 if (class->lc_flags & LC_SLEEPLOCK) 1232 lock_list = &td->td_sleeplocks; 1233 else 1234 lock_list = PCPU_PTR(spinlocks); 1235 for (; *lock_list != NULL; lock_list = &(*lock_list)->ll_next) 1236 for (i = 0; i < (*lock_list)->ll_count; i++) { 1237 instance = &(*lock_list)->ll_children[i]; 1238 if (instance->li_lock == lock) 1239 goto found; 1240 } 1241 panic("lock (%s) %s not locked @ %s:%d", class->lc_name, lock->lo_name, 1242 file, line); 1243 found: 1244 1245 /* First, check for shared/exclusive mismatches. */ 1246 if ((instance->li_flags & LI_EXCLUSIVE) != 0 && 1247 (flags & LOP_EXCLUSIVE) == 0) { 1248 printf("shared unlock of (%s) %s @ %s:%d\n", class->lc_name, 1249 lock->lo_name, file, line); 1250 printf("while exclusively locked from %s:%d\n", 1251 instance->li_file, instance->li_line); 1252 panic("excl->ushare"); 1253 } 1254 if ((instance->li_flags & LI_EXCLUSIVE) == 0 && 1255 (flags & LOP_EXCLUSIVE) != 0) { 1256 printf("exclusive unlock of (%s) %s @ %s:%d\n", class->lc_name, 1257 lock->lo_name, file, line); 1258 printf("while share locked from %s:%d\n", instance->li_file, 1259 instance->li_line); 1260 panic("share->uexcl"); 1261 } 1262 1263 /* If we are recursed, unrecurse. */ 1264 if ((instance->li_flags & LI_RECURSEMASK) > 0) { 1265 CTR4(KTR_WITNESS, "%s: pid %d unrecursed on %s r=%d", __func__, 1266 td->td_proc->p_pid, instance->li_lock->lo_name, 1267 instance->li_flags); 1268 instance->li_flags--; 1269 return; 1270 } 1271 1272 /* Otherwise, remove this item from the list. */ 1273 s = intr_disable(); 1274 CTR4(KTR_WITNESS, "%s: pid %d removed %s from lle[%d]", __func__, 1275 td->td_proc->p_pid, instance->li_lock->lo_name, 1276 (*lock_list)->ll_count - 1); 1277 for (j = i; j < (*lock_list)->ll_count - 1; j++) 1278 (*lock_list)->ll_children[j] = 1279 (*lock_list)->ll_children[j + 1]; 1280 (*lock_list)->ll_count--; 1281 intr_restore(s); 1282 1283 /* If this lock list entry is now empty, free it. */ 1284 if ((*lock_list)->ll_count == 0) { 1285 lle = *lock_list; 1286 *lock_list = lle->ll_next; 1287 CTR3(KTR_WITNESS, "%s: pid %d removed lle %p", __func__, 1288 td->td_proc->p_pid, lle); 1289 witness_lock_list_free(lle); 1290 } 1291 } 1292 1293 /* 1294 * Warn if any locks other than 'lock' are held. Flags can be passed in to 1295 * exempt Giant and sleepable locks from the checks as well. If any 1296 * non-exempt locks are held, then a supplied message is printed to the 1297 * console along with a list of the offending locks. If indicated in the 1298 * flags then a failure results in a panic as well. 1299 */ 1300 int 1301 witness_warn(int flags, struct lock_object *lock, const char *fmt, ...) 1302 { 1303 struct lock_list_entry *lle; 1304 struct lock_instance *lock1; 1305 struct thread *td; 1306 va_list ap; 1307 int i, n; 1308 1309 if (witness_cold || witness_watch == 0 || panicstr != NULL) 1310 return (0); 1311 n = 0; 1312 td = curthread; 1313 for (lle = td->td_sleeplocks; lle != NULL; lle = lle->ll_next) 1314 for (i = lle->ll_count - 1; i >= 0; i--) { 1315 lock1 = &lle->ll_children[i]; 1316 if (lock1->li_lock == lock) 1317 continue; 1318 if (flags & WARN_GIANTOK && 1319 lock1->li_lock == &Giant.mtx_object) 1320 continue; 1321 if (flags & WARN_SLEEPOK && 1322 (lock1->li_lock->lo_flags & LO_SLEEPABLE) != 0) 1323 continue; 1324 if (n == 0) { 1325 va_start(ap, fmt); 1326 vprintf(fmt, ap); 1327 va_end(ap); 1328 printf(" with the following"); 1329 if (flags & WARN_SLEEPOK) 1330 printf(" non-sleepable"); 1331 printf(" locks held:\n"); 1332 } 1333 n++; 1334 witness_list_lock(lock1); 1335 } 1336 if (PCPU_GET(spinlocks) != NULL) { 1337 /* 1338 * Since we already hold a spinlock preemption is 1339 * already blocked. 1340 */ 1341 if (n == 0) { 1342 va_start(ap, fmt); 1343 vprintf(fmt, ap); 1344 va_end(ap); 1345 printf(" with the following"); 1346 if (flags & WARN_SLEEPOK) 1347 printf(" non-sleepable"); 1348 printf(" locks held:\n"); 1349 } 1350 n += witness_list_locks(PCPU_PTR(spinlocks)); 1351 } 1352 if (flags & WARN_PANIC && n) 1353 panic("witness_warn"); 1354 #ifdef KDB 1355 else if (witness_kdb && n) 1356 kdb_enter(__func__); 1357 else if (witness_trace && n) 1358 kdb_backtrace(); 1359 #endif 1360 return (n); 1361 } 1362 1363 const char * 1364 witness_file(struct lock_object *lock) 1365 { 1366 struct witness *w; 1367 1368 if (witness_cold || witness_watch == 0 || lock->lo_witness == NULL) 1369 return ("?"); 1370 w = lock->lo_witness; 1371 return (w->w_file); 1372 } 1373 1374 int 1375 witness_line(struct lock_object *lock) 1376 { 1377 struct witness *w; 1378 1379 if (witness_cold || witness_watch == 0 || lock->lo_witness == NULL) 1380 return (0); 1381 w = lock->lo_witness; 1382 return (w->w_line); 1383 } 1384 1385 static struct witness * 1386 enroll(const char *description, struct lock_class *lock_class) 1387 { 1388 struct witness *w; 1389 1390 if (witness_watch == 0 || panicstr != NULL) 1391 return (NULL); 1392 if ((lock_class->lc_flags & LC_SPINLOCK) && witness_skipspin) 1393 return (NULL); 1394 mtx_lock_spin(&w_mtx); 1395 STAILQ_FOREACH(w, &w_all, w_list) { 1396 if (w->w_name == description || (w->w_refcount > 0 && 1397 strcmp(description, w->w_name) == 0)) { 1398 w->w_refcount++; 1399 mtx_unlock_spin(&w_mtx); 1400 if (lock_class != w->w_class) 1401 panic( 1402 "lock (%s) %s does not match earlier (%s) lock", 1403 description, lock_class->lc_name, 1404 w->w_class->lc_name); 1405 return (w); 1406 } 1407 } 1408 if ((w = witness_get()) == NULL) 1409 goto out; 1410 w->w_name = description; 1411 w->w_class = lock_class; 1412 w->w_refcount = 1; 1413 STAILQ_INSERT_HEAD(&w_all, w, w_list); 1414 if (lock_class->lc_flags & LC_SPINLOCK) { 1415 STAILQ_INSERT_HEAD(&w_spin, w, w_typelist); 1416 w_spin_cnt++; 1417 } else if (lock_class->lc_flags & LC_SLEEPLOCK) { 1418 STAILQ_INSERT_HEAD(&w_sleep, w, w_typelist); 1419 w_sleep_cnt++; 1420 } else { 1421 mtx_unlock_spin(&w_mtx); 1422 panic("lock class %s is not sleep or spin", 1423 lock_class->lc_name); 1424 } 1425 mtx_unlock_spin(&w_mtx); 1426 out: 1427 /* 1428 * We issue a warning for any spin locks not defined in the static 1429 * order list as a way to discourage their use (folks should really 1430 * be using non-spin mutexes most of the time). However, several 1431 * 3rd part device drivers use spin locks because that is all they 1432 * have available on Windows and Linux and they think that normal 1433 * mutexes are insufficient. 1434 */ 1435 if ((lock_class->lc_flags & LC_SPINLOCK) && witness_spin_warn) 1436 printf("WITNESS: spin lock %s not in order list\n", 1437 description); 1438 return (w); 1439 } 1440 1441 /* Don't let the door bang you on the way out... */ 1442 static int 1443 depart(struct witness *w) 1444 { 1445 struct witness_child_list_entry *wcl, *nwcl; 1446 struct witness_list *list; 1447 struct witness *parent; 1448 1449 MPASS(w->w_refcount == 0); 1450 if (w->w_class->lc_flags & LC_SLEEPLOCK) { 1451 list = &w_sleep; 1452 w_sleep_cnt--; 1453 } else { 1454 list = &w_spin; 1455 w_spin_cnt--; 1456 } 1457 /* 1458 * First, we run through the entire tree looking for any 1459 * witnesses that the outgoing witness is a child of. For 1460 * each parent that we find, we reparent all the direct 1461 * children of the outgoing witness to its parent. 1462 */ 1463 STAILQ_FOREACH(parent, list, w_typelist) { 1464 if (!isitmychild(parent, w)) 1465 continue; 1466 removechild(parent, w); 1467 } 1468 1469 /* 1470 * Now we go through and free up the child list of the 1471 * outgoing witness. 1472 */ 1473 for (wcl = w->w_children; wcl != NULL; wcl = nwcl) { 1474 nwcl = wcl->wcl_next; 1475 w_child_cnt--; 1476 witness_child_free(wcl); 1477 } 1478 1479 /* 1480 * Detach from various lists and free. 1481 */ 1482 STAILQ_REMOVE(list, w, witness, w_typelist); 1483 STAILQ_REMOVE(&w_all, w, witness, w_list); 1484 witness_free(w); 1485 1486 return (1); 1487 } 1488 1489 /* 1490 * Add "child" as a direct child of "parent". Returns false if 1491 * we fail due to out of memory. 1492 */ 1493 static int 1494 insertchild(struct witness *parent, struct witness *child) 1495 { 1496 struct witness_child_list_entry **wcl; 1497 1498 MPASS(child != NULL && parent != NULL); 1499 1500 /* 1501 * Insert "child" after "parent" 1502 */ 1503 wcl = &parent->w_children; 1504 while (*wcl != NULL && (*wcl)->wcl_count == WITNESS_NCHILDREN) 1505 wcl = &(*wcl)->wcl_next; 1506 if (*wcl == NULL) { 1507 *wcl = witness_child_get(); 1508 if (*wcl == NULL) 1509 return (0); 1510 w_child_cnt++; 1511 } 1512 (*wcl)->wcl_children[(*wcl)->wcl_count++] = child; 1513 1514 return (1); 1515 } 1516 1517 1518 static int 1519 itismychild(struct witness *parent, struct witness *child) 1520 { 1521 struct witness_list *list; 1522 1523 MPASS(child != NULL && parent != NULL); 1524 if ((parent->w_class->lc_flags & (LC_SLEEPLOCK | LC_SPINLOCK)) != 1525 (child->w_class->lc_flags & (LC_SLEEPLOCK | LC_SPINLOCK))) 1526 panic( 1527 "%s: parent (%s) and child (%s) are not the same lock type", 1528 __func__, parent->w_class->lc_name, 1529 child->w_class->lc_name); 1530 1531 if (!insertchild(parent, child)) 1532 return (0); 1533 1534 if (parent->w_class->lc_flags & LC_SLEEPLOCK) 1535 list = &w_sleep; 1536 else 1537 list = &w_spin; 1538 return (1); 1539 } 1540 1541 static void 1542 removechild(struct witness *parent, struct witness *child) 1543 { 1544 struct witness_child_list_entry **wcl, *wcl1; 1545 int i; 1546 1547 for (wcl = &parent->w_children; *wcl != NULL; wcl = &(*wcl)->wcl_next) 1548 for (i = 0; i < (*wcl)->wcl_count; i++) 1549 if ((*wcl)->wcl_children[i] == child) 1550 goto found; 1551 return; 1552 found: 1553 (*wcl)->wcl_count--; 1554 if ((*wcl)->wcl_count > i) 1555 (*wcl)->wcl_children[i] = 1556 (*wcl)->wcl_children[(*wcl)->wcl_count]; 1557 MPASS((*wcl)->wcl_children[i] != NULL); 1558 if ((*wcl)->wcl_count != 0) 1559 return; 1560 wcl1 = *wcl; 1561 *wcl = wcl1->wcl_next; 1562 w_child_cnt--; 1563 witness_child_free(wcl1); 1564 } 1565 1566 static int 1567 isitmychild(struct witness *parent, struct witness *child) 1568 { 1569 struct witness_child_list_entry *wcl; 1570 int i; 1571 1572 for (wcl = parent->w_children; wcl != NULL; wcl = wcl->wcl_next) { 1573 for (i = 0; i < wcl->wcl_count; i++) { 1574 if (wcl->wcl_children[i] == child) 1575 return (1); 1576 } 1577 } 1578 return (0); 1579 } 1580 1581 static int 1582 isitmydescendant(struct witness *parent, struct witness *child) 1583 { 1584 struct witness_child_list_entry *wcl; 1585 int i, j; 1586 1587 if (isitmychild(parent, child)) 1588 return (1); 1589 j = 0; 1590 for (wcl = parent->w_children; wcl != NULL; wcl = wcl->wcl_next) { 1591 MPASS(j < 1000); 1592 for (i = 0; i < wcl->wcl_count; i++) { 1593 if (isitmydescendant(wcl->wcl_children[i], child)) 1594 return (1); 1595 } 1596 j++; 1597 } 1598 return (0); 1599 } 1600 1601 #ifdef BLESSING 1602 static int 1603 blessed(struct witness *w1, struct witness *w2) 1604 { 1605 int i; 1606 struct witness_blessed *b; 1607 1608 for (i = 0; i < blessed_count; i++) { 1609 b = &blessed_list[i]; 1610 if (strcmp(w1->w_name, b->b_lock1) == 0) { 1611 if (strcmp(w2->w_name, b->b_lock2) == 0) 1612 return (1); 1613 continue; 1614 } 1615 if (strcmp(w1->w_name, b->b_lock2) == 0) 1616 if (strcmp(w2->w_name, b->b_lock1) == 0) 1617 return (1); 1618 } 1619 return (0); 1620 } 1621 #endif 1622 1623 static struct witness * 1624 witness_get(void) 1625 { 1626 struct witness *w; 1627 1628 if (witness_watch == 0) { 1629 mtx_unlock_spin(&w_mtx); 1630 return (NULL); 1631 } 1632 if (STAILQ_EMPTY(&w_free)) { 1633 witness_watch = 0; 1634 mtx_unlock_spin(&w_mtx); 1635 printf("%s: witness exhausted\n", __func__); 1636 return (NULL); 1637 } 1638 w = STAILQ_FIRST(&w_free); 1639 STAILQ_REMOVE_HEAD(&w_free, w_list); 1640 w_free_cnt--; 1641 bzero(w, sizeof(*w)); 1642 return (w); 1643 } 1644 1645 static void 1646 witness_free(struct witness *w) 1647 { 1648 1649 STAILQ_INSERT_HEAD(&w_free, w, w_list); 1650 w_free_cnt++; 1651 } 1652 1653 static struct witness_child_list_entry * 1654 witness_child_get(void) 1655 { 1656 struct witness_child_list_entry *wcl; 1657 1658 if (witness_watch == 0) { 1659 mtx_unlock_spin(&w_mtx); 1660 return (NULL); 1661 } 1662 wcl = w_child_free; 1663 if (wcl == NULL) { 1664 witness_watch = 0; 1665 mtx_unlock_spin(&w_mtx); 1666 printf("%s: witness exhausted\n", __func__); 1667 return (NULL); 1668 } 1669 w_child_free = wcl->wcl_next; 1670 w_child_free_cnt--; 1671 bzero(wcl, sizeof(*wcl)); 1672 return (wcl); 1673 } 1674 1675 static void 1676 witness_child_free(struct witness_child_list_entry *wcl) 1677 { 1678 1679 wcl->wcl_next = w_child_free; 1680 w_child_free = wcl; 1681 w_child_free_cnt++; 1682 } 1683 1684 static struct lock_list_entry * 1685 witness_lock_list_get(void) 1686 { 1687 struct lock_list_entry *lle; 1688 1689 if (witness_watch == 0) 1690 return (NULL); 1691 mtx_lock_spin(&w_mtx); 1692 lle = w_lock_list_free; 1693 if (lle == NULL) { 1694 witness_watch = 0; 1695 mtx_unlock_spin(&w_mtx); 1696 printf("%s: witness exhausted\n", __func__); 1697 return (NULL); 1698 } 1699 w_lock_list_free = lle->ll_next; 1700 mtx_unlock_spin(&w_mtx); 1701 bzero(lle, sizeof(*lle)); 1702 return (lle); 1703 } 1704 1705 static void 1706 witness_lock_list_free(struct lock_list_entry *lle) 1707 { 1708 1709 mtx_lock_spin(&w_mtx); 1710 lle->ll_next = w_lock_list_free; 1711 w_lock_list_free = lle; 1712 mtx_unlock_spin(&w_mtx); 1713 } 1714 1715 static struct lock_instance * 1716 find_instance(struct lock_list_entry *lock_list, struct lock_object *lock) 1717 { 1718 struct lock_list_entry *lle; 1719 struct lock_instance *instance; 1720 int i; 1721 1722 for (lle = lock_list; lle != NULL; lle = lle->ll_next) 1723 for (i = lle->ll_count - 1; i >= 0; i--) { 1724 instance = &lle->ll_children[i]; 1725 if (instance->li_lock == lock) 1726 return (instance); 1727 } 1728 return (NULL); 1729 } 1730 1731 static void 1732 witness_list_lock(struct lock_instance *instance) 1733 { 1734 struct lock_object *lock; 1735 1736 lock = instance->li_lock; 1737 printf("%s %s %s", (instance->li_flags & LI_EXCLUSIVE) != 0 ? 1738 "exclusive" : "shared", LOCK_CLASS(lock)->lc_name, lock->lo_name); 1739 if (lock->lo_type != lock->lo_name) 1740 printf(" (%s)", lock->lo_type); 1741 printf(" r = %d (%p) locked @ %s:%d\n", 1742 instance->li_flags & LI_RECURSEMASK, lock, instance->li_file, 1743 instance->li_line); 1744 } 1745 1746 #ifdef DDB 1747 static int 1748 witness_thread_has_locks(struct thread *td) 1749 { 1750 1751 return (td->td_sleeplocks != NULL); 1752 } 1753 1754 static int 1755 witness_proc_has_locks(struct proc *p) 1756 { 1757 struct thread *td; 1758 1759 FOREACH_THREAD_IN_PROC(p, td) { 1760 if (witness_thread_has_locks(td)) 1761 return (1); 1762 } 1763 return (0); 1764 } 1765 #endif 1766 1767 int 1768 witness_list_locks(struct lock_list_entry **lock_list) 1769 { 1770 struct lock_list_entry *lle; 1771 int i, nheld; 1772 1773 nheld = 0; 1774 for (lle = *lock_list; lle != NULL; lle = lle->ll_next) 1775 for (i = lle->ll_count - 1; i >= 0; i--) { 1776 witness_list_lock(&lle->ll_children[i]); 1777 nheld++; 1778 } 1779 return (nheld); 1780 } 1781 1782 /* 1783 * This is a bit risky at best. We call this function when we have timed 1784 * out acquiring a spin lock, and we assume that the other CPU is stuck 1785 * with this lock held. So, we go groveling around in the other CPU's 1786 * per-cpu data to try to find the lock instance for this spin lock to 1787 * see when it was last acquired. 1788 */ 1789 void 1790 witness_display_spinlock(struct lock_object *lock, struct thread *owner) 1791 { 1792 struct lock_instance *instance; 1793 struct pcpu *pc; 1794 1795 if (owner->td_critnest == 0 || owner->td_oncpu == NOCPU) 1796 return; 1797 pc = pcpu_find(owner->td_oncpu); 1798 instance = find_instance(pc->pc_spinlocks, lock); 1799 if (instance != NULL) 1800 witness_list_lock(instance); 1801 } 1802 1803 void 1804 witness_save(struct lock_object *lock, const char **filep, int *linep) 1805 { 1806 struct lock_list_entry *lock_list; 1807 struct lock_instance *instance; 1808 struct lock_class *class; 1809 1810 KASSERT(!witness_cold, ("%s: witness_cold", __func__)); 1811 if (lock->lo_witness == NULL || witness_watch == 0 || panicstr != NULL) 1812 return; 1813 class = LOCK_CLASS(lock); 1814 if (class->lc_flags & LC_SLEEPLOCK) 1815 lock_list = curthread->td_sleeplocks; 1816 else { 1817 if (witness_skipspin) 1818 return; 1819 lock_list = PCPU_GET(spinlocks); 1820 } 1821 instance = find_instance(lock_list, lock); 1822 if (instance == NULL) 1823 panic("%s: lock (%s) %s not locked", __func__, 1824 class->lc_name, lock->lo_name); 1825 *filep = instance->li_file; 1826 *linep = instance->li_line; 1827 } 1828 1829 void 1830 witness_restore(struct lock_object *lock, const char *file, int line) 1831 { 1832 struct lock_list_entry *lock_list; 1833 struct lock_instance *instance; 1834 struct lock_class *class; 1835 1836 KASSERT(!witness_cold, ("%s: witness_cold", __func__)); 1837 if (lock->lo_witness == NULL || witness_watch == 0 || panicstr != NULL) 1838 return; 1839 class = LOCK_CLASS(lock); 1840 if (class->lc_flags & LC_SLEEPLOCK) 1841 lock_list = curthread->td_sleeplocks; 1842 else { 1843 if (witness_skipspin) 1844 return; 1845 lock_list = PCPU_GET(spinlocks); 1846 } 1847 instance = find_instance(lock_list, lock); 1848 if (instance == NULL) 1849 panic("%s: lock (%s) %s not locked", __func__, 1850 class->lc_name, lock->lo_name); 1851 lock->lo_witness->w_file = file; 1852 lock->lo_witness->w_line = line; 1853 instance->li_file = file; 1854 instance->li_line = line; 1855 } 1856 1857 void 1858 witness_assert(struct lock_object *lock, int flags, const char *file, int line) 1859 { 1860 #ifdef INVARIANT_SUPPORT 1861 struct lock_instance *instance; 1862 struct lock_class *class; 1863 1864 if (lock->lo_witness == NULL || witness_watch == 0 || panicstr != NULL) 1865 return; 1866 class = LOCK_CLASS(lock); 1867 if ((class->lc_flags & LC_SLEEPLOCK) != 0) 1868 instance = find_instance(curthread->td_sleeplocks, lock); 1869 else if ((class->lc_flags & LC_SPINLOCK) != 0) 1870 instance = find_instance(PCPU_GET(spinlocks), lock); 1871 else { 1872 panic("Lock (%s) %s is not sleep or spin!", 1873 class->lc_name, lock->lo_name); 1874 } 1875 file = fixup_filename(file); 1876 switch (flags) { 1877 case LA_UNLOCKED: 1878 if (instance != NULL) 1879 panic("Lock (%s) %s locked @ %s:%d.", 1880 class->lc_name, lock->lo_name, file, line); 1881 break; 1882 case LA_LOCKED: 1883 case LA_LOCKED | LA_RECURSED: 1884 case LA_LOCKED | LA_NOTRECURSED: 1885 case LA_SLOCKED: 1886 case LA_SLOCKED | LA_RECURSED: 1887 case LA_SLOCKED | LA_NOTRECURSED: 1888 case LA_XLOCKED: 1889 case LA_XLOCKED | LA_RECURSED: 1890 case LA_XLOCKED | LA_NOTRECURSED: 1891 if (instance == NULL) { 1892 panic("Lock (%s) %s not locked @ %s:%d.", 1893 class->lc_name, lock->lo_name, file, line); 1894 break; 1895 } 1896 if ((flags & LA_XLOCKED) != 0 && 1897 (instance->li_flags & LI_EXCLUSIVE) == 0) 1898 panic("Lock (%s) %s not exclusively locked @ %s:%d.", 1899 class->lc_name, lock->lo_name, file, line); 1900 if ((flags & LA_SLOCKED) != 0 && 1901 (instance->li_flags & LI_EXCLUSIVE) != 0) 1902 panic("Lock (%s) %s exclusively locked @ %s:%d.", 1903 class->lc_name, lock->lo_name, file, line); 1904 if ((flags & LA_RECURSED) != 0 && 1905 (instance->li_flags & LI_RECURSEMASK) == 0) 1906 panic("Lock (%s) %s not recursed @ %s:%d.", 1907 class->lc_name, lock->lo_name, file, line); 1908 if ((flags & LA_NOTRECURSED) != 0 && 1909 (instance->li_flags & LI_RECURSEMASK) != 0) 1910 panic("Lock (%s) %s recursed @ %s:%d.", 1911 class->lc_name, lock->lo_name, file, line); 1912 break; 1913 default: 1914 panic("Invalid lock assertion at %s:%d.", file, line); 1915 1916 } 1917 #endif /* INVARIANT_SUPPORT */ 1918 } 1919 1920 #ifdef DDB 1921 static void 1922 witness_list(struct thread *td) 1923 { 1924 1925 KASSERT(!witness_cold, ("%s: witness_cold", __func__)); 1926 KASSERT(kdb_active, ("%s: not in the debugger", __func__)); 1927 1928 if (witness_watch == 0) 1929 return; 1930 1931 witness_list_locks(&td->td_sleeplocks); 1932 1933 /* 1934 * We only handle spinlocks if td == curthread. This is somewhat broken 1935 * if td is currently executing on some other CPU and holds spin locks 1936 * as we won't display those locks. If we had a MI way of getting 1937 * the per-cpu data for a given cpu then we could use 1938 * td->td_oncpu to get the list of spinlocks for this thread 1939 * and "fix" this. 1940 * 1941 * That still wouldn't really fix this unless we locked sched_lock 1942 * or stopped the other CPU to make sure it wasn't changing the list 1943 * out from under us. It is probably best to just not try to handle 1944 * threads on other CPU's for now. 1945 */ 1946 if (td == curthread && PCPU_GET(spinlocks) != NULL) 1947 witness_list_locks(PCPU_PTR(spinlocks)); 1948 } 1949 1950 DB_SHOW_COMMAND(locks, db_witness_list) 1951 { 1952 struct thread *td; 1953 pid_t pid; 1954 struct proc *p; 1955 1956 if (have_addr) { 1957 pid = (addr % 16) + ((addr >> 4) % 16) * 10 + 1958 ((addr >> 8) % 16) * 100 + ((addr >> 12) % 16) * 1000 + 1959 ((addr >> 16) % 16) * 10000; 1960 /* sx_slock(&allproc_lock); */ 1961 FOREACH_PROC_IN_SYSTEM(p) { 1962 if (p->p_pid == pid) 1963 break; 1964 } 1965 /* sx_sunlock(&allproc_lock); */ 1966 if (p == NULL) { 1967 db_printf("pid %d not found\n", pid); 1968 return; 1969 } 1970 FOREACH_THREAD_IN_PROC(p, td) { 1971 witness_list(td); 1972 } 1973 } else { 1974 td = curthread; 1975 witness_list(td); 1976 } 1977 } 1978 1979 DB_SHOW_COMMAND(alllocks, db_witness_list_all) 1980 { 1981 struct thread *td; 1982 struct proc *p; 1983 1984 /* 1985 * It would be nice to list only threads and processes that actually 1986 * held sleep locks, but that information is currently not exported 1987 * by WITNESS. 1988 */ 1989 FOREACH_PROC_IN_SYSTEM(p) { 1990 if (!witness_proc_has_locks(p)) 1991 continue; 1992 FOREACH_THREAD_IN_PROC(p, td) { 1993 if (!witness_thread_has_locks(td)) 1994 continue; 1995 db_printf("Process %d (%s) thread %p (%d)\n", p->p_pid, 1996 p->p_comm, td, td->td_tid); 1997 witness_list(td); 1998 } 1999 } 2000 } 2001 2002 DB_SHOW_COMMAND(witness, db_witness_display) 2003 { 2004 2005 witness_display(db_printf); 2006 } 2007 #endif
Cache object: 4190dc0bece75179cb5ba34091056355
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