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: releng/6.1/sys/kern/subr_witness.c 157869 2006-04-19 16:00:05Z jhb $"); 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 * CDEV 353 */ 354 { "system map", &lock_class_mtx_sleep }, 355 { "vm page queue mutex", &lock_class_mtx_sleep }, 356 { "vnode interlock", &lock_class_mtx_sleep }, 357 { "cdev", &lock_class_mtx_sleep }, 358 { NULL, NULL }, 359 /* 360 * spin locks 361 */ 362 #ifdef SMP 363 { "ap boot", &lock_class_mtx_spin }, 364 #endif 365 { "rm.mutex_mtx", &lock_class_mtx_spin }, 366 { "sio", &lock_class_mtx_spin }, 367 #ifdef __i386__ 368 { "cy", &lock_class_mtx_spin }, 369 #endif 370 { "uart_hwmtx", &lock_class_mtx_spin }, 371 { "sabtty", &lock_class_mtx_spin }, 372 { "zstty", &lock_class_mtx_spin }, 373 { "ng_node", &lock_class_mtx_spin }, 374 { "ng_worklist", &lock_class_mtx_spin }, 375 { "taskqueue_fast", &lock_class_mtx_spin }, 376 { "intr table", &lock_class_mtx_spin }, 377 { "sleepq chain", &lock_class_mtx_spin }, 378 { "sched lock", &lock_class_mtx_spin }, 379 { "turnstile chain", &lock_class_mtx_spin }, 380 { "td_contested", &lock_class_mtx_spin }, 381 { "callout", &lock_class_mtx_spin }, 382 { "entropy harvest mutex", &lock_class_mtx_spin }, 383 /* 384 * leaf locks 385 */ 386 { "allpmaps", &lock_class_mtx_spin }, 387 { "vm page queue free mutex", &lock_class_mtx_spin }, 388 { "icu", &lock_class_mtx_spin }, 389 #ifdef SMP 390 { "smp rendezvous", &lock_class_mtx_spin }, 391 #if defined(__i386__) || defined(__amd64__) 392 { "tlb", &lock_class_mtx_spin }, 393 #endif 394 #ifdef __sparc64__ 395 { "ipi", &lock_class_mtx_spin }, 396 { "rtc_mtx", &lock_class_mtx_spin }, 397 #endif 398 #endif 399 { "clk", &lock_class_mtx_spin }, 400 { "mutex profiling lock", &lock_class_mtx_spin }, 401 { "kse zombie lock", &lock_class_mtx_spin }, 402 { "ALD Queue", &lock_class_mtx_spin }, 403 #ifdef __ia64__ 404 { "MCA spin lock", &lock_class_mtx_spin }, 405 #endif 406 #if defined(__i386__) || defined(__amd64__) 407 { "pcicfg", &lock_class_mtx_spin }, 408 { "NDIS thread lock", &lock_class_mtx_spin }, 409 #endif 410 { "tw_osl_io_lock", &lock_class_mtx_spin }, 411 { "tw_osl_q_lock", &lock_class_mtx_spin }, 412 { "tw_cl_io_lock", &lock_class_mtx_spin }, 413 { "tw_cl_intr_lock", &lock_class_mtx_spin }, 414 { "tw_cl_gen_lock", &lock_class_mtx_spin }, 415 { NULL, NULL }, 416 { NULL, NULL } 417 }; 418 419 #ifdef BLESSING 420 /* 421 * Pairs of locks which have been blessed 422 * Don't complain about order problems with blessed locks 423 */ 424 static struct witness_blessed blessed_list[] = { 425 }; 426 static int blessed_count = 427 sizeof(blessed_list) / sizeof(struct witness_blessed); 428 #endif 429 430 /* 431 * List of all locks in the system. 432 */ 433 TAILQ_HEAD(, lock_object) all_locks = TAILQ_HEAD_INITIALIZER(all_locks); 434 435 static struct mtx all_mtx = { 436 { &lock_class_mtx_sleep, /* mtx_object.lo_class */ 437 "All locks list", /* mtx_object.lo_name */ 438 "All locks list", /* mtx_object.lo_type */ 439 LO_INITIALIZED, /* mtx_object.lo_flags */ 440 { NULL, NULL }, /* mtx_object.lo_list */ 441 NULL }, /* mtx_object.lo_witness */ 442 MTX_UNOWNED, 0 /* mtx_lock, mtx_recurse */ 443 }; 444 445 /* 446 * This global is set to 0 once it becomes safe to use the witness code. 447 */ 448 static int witness_cold = 1; 449 450 /* 451 * This global is set to 1 once the static lock orders have been enrolled 452 * so that a warning can be issued for any spin locks enrolled later. 453 */ 454 static int witness_spin_warn = 0; 455 456 /* 457 * Global variables for book keeping. 458 */ 459 static int lock_cur_cnt; 460 static int lock_max_cnt; 461 462 /* 463 * The WITNESS-enabled diagnostic code. 464 */ 465 static void 466 witness_initialize(void *dummy __unused) 467 { 468 struct lock_object *lock; 469 struct witness_order_list_entry *order; 470 struct witness *w, *w1; 471 int i; 472 473 /* 474 * We have to release Giant before initializing its witness 475 * structure so that WITNESS doesn't get confused. 476 */ 477 mtx_unlock(&Giant); 478 mtx_assert(&Giant, MA_NOTOWNED); 479 480 CTR1(KTR_WITNESS, "%s: initializing witness", __func__); 481 TAILQ_INSERT_HEAD(&all_locks, &all_mtx.mtx_object, lo_list); 482 mtx_init(&w_mtx, "witness lock", NULL, MTX_SPIN | MTX_QUIET | 483 MTX_NOWITNESS); 484 for (i = 0; i < WITNESS_COUNT; i++) 485 witness_free(&w_data[i]); 486 for (i = 0; i < WITNESS_CHILDCOUNT; i++) 487 witness_child_free(&w_childdata[i]); 488 for (i = 0; i < LOCK_CHILDCOUNT; i++) 489 witness_lock_list_free(&w_locklistdata[i]); 490 491 /* First add in all the specified order lists. */ 492 for (order = order_lists; order->w_name != NULL; order++) { 493 w = enroll(order->w_name, order->w_class); 494 if (w == NULL) 495 continue; 496 w->w_file = "order list"; 497 for (order++; order->w_name != NULL; order++) { 498 w1 = enroll(order->w_name, order->w_class); 499 if (w1 == NULL) 500 continue; 501 w1->w_file = "order list"; 502 if (!itismychild(w, w1)) 503 panic("Not enough memory for static orders!"); 504 w = w1; 505 } 506 } 507 witness_spin_warn = 1; 508 509 /* Iterate through all locks and add them to witness. */ 510 mtx_lock(&all_mtx); 511 TAILQ_FOREACH(lock, &all_locks, lo_list) { 512 if (lock->lo_flags & LO_WITNESS) 513 lock->lo_witness = enroll(lock->lo_type, 514 lock->lo_class); 515 else 516 lock->lo_witness = NULL; 517 } 518 mtx_unlock(&all_mtx); 519 520 /* Mark the witness code as being ready for use. */ 521 witness_cold = 0; 522 523 mtx_lock(&Giant); 524 } 525 SYSINIT(witness_init, SI_SUB_WITNESS, SI_ORDER_FIRST, witness_initialize, NULL) 526 527 static int 528 sysctl_debug_witness_watch(SYSCTL_HANDLER_ARGS) 529 { 530 int error, value; 531 532 value = witness_watch; 533 error = sysctl_handle_int(oidp, &value, 0, req); 534 if (error != 0 || req->newptr == NULL) 535 return (error); 536 error = suser(req->td); 537 if (error != 0) 538 return (error); 539 if (value == witness_watch) 540 return (0); 541 if (value != 0) 542 return (EINVAL); 543 witness_watch = 0; 544 return (0); 545 } 546 547 void 548 witness_init(struct lock_object *lock) 549 { 550 struct lock_class *class; 551 552 class = lock->lo_class; 553 if (lock->lo_flags & LO_INITIALIZED) 554 panic("%s: lock (%s) %s is already initialized", __func__, 555 class->lc_name, lock->lo_name); 556 if ((lock->lo_flags & LO_RECURSABLE) != 0 && 557 (class->lc_flags & LC_RECURSABLE) == 0) 558 panic("%s: lock (%s) %s can not be recursable", __func__, 559 class->lc_name, lock->lo_name); 560 if ((lock->lo_flags & LO_SLEEPABLE) != 0 && 561 (class->lc_flags & LC_SLEEPABLE) == 0) 562 panic("%s: lock (%s) %s can not be sleepable", __func__, 563 class->lc_name, lock->lo_name); 564 if ((lock->lo_flags & LO_UPGRADABLE) != 0 && 565 (class->lc_flags & LC_UPGRADABLE) == 0) 566 panic("%s: lock (%s) %s can not be upgradable", __func__, 567 class->lc_name, lock->lo_name); 568 569 mtx_lock(&all_mtx); 570 TAILQ_INSERT_TAIL(&all_locks, lock, lo_list); 571 lock->lo_flags |= LO_INITIALIZED; 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 witness *w; 587 588 if (witness_cold) 589 panic("lock (%s) %s destroyed while witness_cold", 590 lock->lo_class->lc_name, lock->lo_name); 591 if ((lock->lo_flags & LO_INITIALIZED) == 0) 592 panic("%s: lock (%s) %s is not initialized", __func__, 593 lock->lo_class->lc_name, lock->lo_name); 594 595 /* XXX: need to verify that no one holds the lock */ 596 w = lock->lo_witness; 597 if (w != NULL) { 598 mtx_lock_spin(&w_mtx); 599 MPASS(w->w_refcount > 0); 600 w->w_refcount--; 601 602 /* 603 * Lock is already released if we have an allocation failure 604 * and depart() fails. 605 */ 606 if (w->w_refcount != 0 || depart(w)) 607 mtx_unlock_spin(&w_mtx); 608 } 609 610 mtx_lock(&all_mtx); 611 lock_cur_cnt--; 612 TAILQ_REMOVE(&all_locks, lock, lo_list); 613 lock->lo_flags &= ~LO_INITIALIZED; 614 mtx_unlock(&all_mtx); 615 } 616 617 #ifdef DDB 618 static void 619 witness_levelall (void) 620 { 621 struct witness_list *list; 622 struct witness *w, *w1; 623 624 /* 625 * First clear all levels. 626 */ 627 STAILQ_FOREACH(w, &w_all, w_list) { 628 w->w_level = 0; 629 } 630 631 /* 632 * Look for locks with no parent and level all their descendants. 633 */ 634 STAILQ_FOREACH(w, &w_all, w_list) { 635 /* 636 * This is just an optimization, technically we could get 637 * away just walking the all list each time. 638 */ 639 if (w->w_class->lc_flags & LC_SLEEPLOCK) 640 list = &w_sleep; 641 else 642 list = &w_spin; 643 STAILQ_FOREACH(w1, list, w_typelist) { 644 if (isitmychild(w1, w)) 645 goto skip; 646 } 647 witness_leveldescendents(w, 0); 648 skip: 649 ; /* silence GCC 3.x */ 650 } 651 } 652 653 static void 654 witness_leveldescendents(struct witness *parent, int level) 655 { 656 struct witness_child_list_entry *wcl; 657 int i; 658 659 if (parent->w_level < level) 660 parent->w_level = level; 661 level++; 662 for (wcl = parent->w_children; wcl != NULL; wcl = wcl->wcl_next) 663 for (i = 0; i < wcl->wcl_count; i++) 664 witness_leveldescendents(wcl->wcl_children[i], level); 665 } 666 667 static void 668 witness_displaydescendants(void(*prnt)(const char *fmt, ...), 669 struct witness *parent, int indent) 670 { 671 struct witness_child_list_entry *wcl; 672 int i, level; 673 674 level = parent->w_level; 675 prnt("%-2d", level); 676 for (i = 0; i < indent; i++) 677 prnt(" "); 678 if (parent->w_refcount > 0) 679 prnt("%s", parent->w_name); 680 else 681 prnt("(dead)"); 682 if (parent->w_displayed) { 683 prnt(" -- (already displayed)\n"); 684 return; 685 } 686 parent->w_displayed = 1; 687 if (parent->w_refcount > 0) { 688 if (parent->w_file != NULL) 689 prnt(" -- last acquired @ %s:%d", parent->w_file, 690 parent->w_line); 691 } 692 prnt("\n"); 693 for (wcl = parent->w_children; wcl != NULL; wcl = wcl->wcl_next) 694 for (i = 0; i < wcl->wcl_count; i++) 695 witness_displaydescendants(prnt, 696 wcl->wcl_children[i], indent + 1); 697 } 698 699 static void 700 witness_display_list(void(*prnt)(const char *fmt, ...), 701 struct witness_list *list) 702 { 703 struct witness *w; 704 705 STAILQ_FOREACH(w, list, w_typelist) { 706 if (w->w_file == NULL || w->w_level > 0) 707 continue; 708 /* 709 * This lock has no anscestors, display its descendants. 710 */ 711 witness_displaydescendants(prnt, w, 0); 712 } 713 } 714 715 static void 716 witness_display(void(*prnt)(const char *fmt, ...)) 717 { 718 struct witness *w; 719 720 KASSERT(!witness_cold, ("%s: witness_cold", __func__)); 721 witness_levelall(); 722 723 /* Clear all the displayed flags. */ 724 STAILQ_FOREACH(w, &w_all, w_list) { 725 w->w_displayed = 0; 726 } 727 728 /* 729 * First, handle sleep locks which have been acquired at least 730 * once. 731 */ 732 prnt("Sleep locks:\n"); 733 witness_display_list(prnt, &w_sleep); 734 735 /* 736 * Now do spin locks which have been acquired at least once. 737 */ 738 prnt("\nSpin locks:\n"); 739 witness_display_list(prnt, &w_spin); 740 741 /* 742 * Finally, any locks which have not been acquired yet. 743 */ 744 prnt("\nLocks which were never acquired:\n"); 745 STAILQ_FOREACH(w, &w_all, w_list) { 746 if (w->w_file != NULL || w->w_refcount == 0) 747 continue; 748 prnt("%s\n", w->w_name); 749 } 750 } 751 #endif /* DDB */ 752 753 /* Trim useless garbage from filenames. */ 754 static const char * 755 fixup_filename(const char *file) 756 { 757 758 if (file == NULL) 759 return (NULL); 760 while (strncmp(file, "../", 3) == 0) 761 file += 3; 762 return (file); 763 } 764 765 int 766 witness_defineorder(struct lock_object *lock1, struct lock_object *lock2) 767 { 768 769 if (witness_watch == 0 || panicstr != NULL) 770 return (0); 771 772 /* Require locks that witness knows about. */ 773 if (lock1 == NULL || lock1->lo_witness == NULL || lock2 == NULL || 774 lock2->lo_witness == NULL) 775 return (EINVAL); 776 777 MPASS(!mtx_owned(&w_mtx)); 778 mtx_lock_spin(&w_mtx); 779 780 /* 781 * If we already have either an explicit or implied lock order that 782 * is the other way around, then return an error. 783 */ 784 if (isitmydescendant(lock2->lo_witness, lock1->lo_witness)) { 785 mtx_unlock_spin(&w_mtx); 786 return (EDOOFUS); 787 } 788 789 /* Try to add the new order. */ 790 CTR3(KTR_WITNESS, "%s: adding %s as a child of %s", __func__, 791 lock2->lo_type, lock1->lo_type); 792 if (!itismychild(lock1->lo_witness, lock2->lo_witness)) 793 return (ENOMEM); 794 mtx_unlock_spin(&w_mtx); 795 return (0); 796 } 797 798 void 799 witness_checkorder(struct lock_object *lock, int flags, const char *file, 800 int line) 801 { 802 struct lock_list_entry **lock_list, *lle; 803 struct lock_instance *lock1, *lock2; 804 struct lock_class *class; 805 struct witness *w, *w1; 806 struct thread *td; 807 int i, j; 808 809 if (witness_cold || witness_watch == 0 || lock->lo_witness == NULL || 810 panicstr != NULL) 811 return; 812 813 /* 814 * Try locks do not block if they fail to acquire the lock, thus 815 * there is no danger of deadlocks or of switching while holding a 816 * spin lock if we acquire a lock via a try operation. This 817 * function shouldn't even be called for try locks, so panic if 818 * that happens. 819 */ 820 if (flags & LOP_TRYLOCK) 821 panic("%s should not be called for try lock operations", 822 __func__); 823 824 w = lock->lo_witness; 825 class = lock->lo_class; 826 td = curthread; 827 file = fixup_filename(file); 828 829 if (class->lc_flags & LC_SLEEPLOCK) { 830 /* 831 * Since spin locks include a critical section, this check 832 * implicitly enforces a lock order of all sleep locks before 833 * all spin locks. 834 */ 835 if (td->td_critnest != 0 && !kdb_active) 836 panic("blockable sleep lock (%s) %s @ %s:%d", 837 class->lc_name, lock->lo_name, file, line); 838 839 /* 840 * If this is the first lock acquired then just return as 841 * no order checking is needed. 842 */ 843 if (td->td_sleeplocks == NULL) 844 return; 845 lock_list = &td->td_sleeplocks; 846 } else { 847 /* 848 * If this is the first lock, just return as no order 849 * checking is needed. We check this in both if clauses 850 * here as unifying the check would require us to use a 851 * critical section to ensure we don't migrate while doing 852 * the check. Note that if this is not the first lock, we 853 * are already in a critical section and are safe for the 854 * rest of the check. 855 */ 856 if (PCPU_GET(spinlocks) == NULL) 857 return; 858 lock_list = PCPU_PTR(spinlocks); 859 } 860 861 /* 862 * Check to see if we are recursing on a lock we already own. If 863 * so, make sure that we don't mismatch exclusive and shared lock 864 * acquires. 865 */ 866 lock1 = find_instance(*lock_list, lock); 867 if (lock1 != NULL) { 868 if ((lock1->li_flags & LI_EXCLUSIVE) != 0 && 869 (flags & LOP_EXCLUSIVE) == 0) { 870 printf("shared lock of (%s) %s @ %s:%d\n", 871 class->lc_name, lock->lo_name, file, line); 872 printf("while exclusively locked from %s:%d\n", 873 lock1->li_file, lock1->li_line); 874 panic("share->excl"); 875 } 876 if ((lock1->li_flags & LI_EXCLUSIVE) == 0 && 877 (flags & LOP_EXCLUSIVE) != 0) { 878 printf("exclusive lock of (%s) %s @ %s:%d\n", 879 class->lc_name, lock->lo_name, file, line); 880 printf("while share locked from %s:%d\n", 881 lock1->li_file, lock1->li_line); 882 panic("excl->share"); 883 } 884 return; 885 } 886 887 /* 888 * Try locks do not block if they fail to acquire the lock, thus 889 * there is no danger of deadlocks or of switching while holding a 890 * spin lock if we acquire a lock via a try operation. 891 */ 892 if (flags & LOP_TRYLOCK) 893 return; 894 895 /* 896 * Check for duplicate locks of the same type. Note that we only 897 * have to check for this on the last lock we just acquired. Any 898 * other cases will be caught as lock order violations. 899 */ 900 lock1 = &(*lock_list)->ll_children[(*lock_list)->ll_count - 1]; 901 w1 = lock1->li_lock->lo_witness; 902 if (w1 == w) { 903 if (w->w_same_squawked || (lock->lo_flags & LO_DUPOK) || 904 (flags & LOP_DUPOK)) 905 return; 906 w->w_same_squawked = 1; 907 printf("acquiring duplicate lock of same type: \"%s\"\n", 908 lock->lo_type); 909 printf(" 1st %s @ %s:%d\n", lock1->li_lock->lo_name, 910 lock1->li_file, lock1->li_line); 911 printf(" 2nd %s @ %s:%d\n", lock->lo_name, file, line); 912 #ifdef KDB 913 goto debugger; 914 #else 915 return; 916 #endif 917 } 918 MPASS(!mtx_owned(&w_mtx)); 919 mtx_lock_spin(&w_mtx); 920 /* 921 * If we know that the the lock we are acquiring comes after 922 * the lock we most recently acquired in the lock order tree, 923 * then there is no need for any further checks. 924 */ 925 if (isitmychild(w1, w)) { 926 mtx_unlock_spin(&w_mtx); 927 return; 928 } 929 for (j = 0, lle = *lock_list; lle != NULL; lle = lle->ll_next) { 930 for (i = lle->ll_count - 1; i >= 0; i--, j++) { 931 932 MPASS(j < WITNESS_COUNT); 933 lock1 = &lle->ll_children[i]; 934 w1 = lock1->li_lock->lo_witness; 935 936 /* 937 * If this lock doesn't undergo witness checking, 938 * then skip it. 939 */ 940 if (w1 == NULL) { 941 KASSERT((lock1->li_lock->lo_flags & LO_WITNESS) == 0, 942 ("lock missing witness structure")); 943 continue; 944 } 945 /* 946 * If we are locking Giant and this is a sleepable 947 * lock, then skip it. 948 */ 949 if ((lock1->li_lock->lo_flags & LO_SLEEPABLE) != 0 && 950 lock == &Giant.mtx_object) 951 continue; 952 /* 953 * If we are locking a sleepable lock and this lock 954 * is Giant, then skip it. 955 */ 956 if ((lock->lo_flags & LO_SLEEPABLE) != 0 && 957 lock1->li_lock == &Giant.mtx_object) 958 continue; 959 /* 960 * If we are locking a sleepable lock and this lock 961 * isn't sleepable, we want to treat it as a lock 962 * order violation to enfore a general lock order of 963 * sleepable locks before non-sleepable locks. 964 */ 965 if (((lock->lo_flags & LO_SLEEPABLE) != 0 && 966 (lock1->li_lock->lo_flags & LO_SLEEPABLE) == 0)) 967 goto reversal; 968 /* 969 * If we are locking Giant and this is a non-sleepable 970 * lock, then treat it as a reversal. 971 */ 972 if ((lock1->li_lock->lo_flags & LO_SLEEPABLE) == 0 && 973 lock == &Giant.mtx_object) 974 goto reversal; 975 /* 976 * Check the lock order hierarchy for a reveresal. 977 */ 978 if (!isitmydescendant(w, w1)) 979 continue; 980 reversal: 981 /* 982 * We have a lock order violation, check to see if it 983 * is allowed or has already been yelled about. 984 */ 985 mtx_unlock_spin(&w_mtx); 986 #ifdef BLESSING 987 /* 988 * If the lock order is blessed, just bail. We don't 989 * look for other lock order violations though, which 990 * may be a bug. 991 */ 992 if (blessed(w, w1)) 993 return; 994 #endif 995 if (lock1->li_lock == &Giant.mtx_object) { 996 if (w1->w_Giant_squawked) 997 return; 998 else 999 w1->w_Giant_squawked = 1; 1000 } else { 1001 if (w1->w_other_squawked) 1002 return; 1003 else 1004 w1->w_other_squawked = 1; 1005 } 1006 /* 1007 * Ok, yell about it. 1008 */ 1009 if (((lock->lo_flags & LO_SLEEPABLE) != 0 && 1010 (lock1->li_lock->lo_flags & LO_SLEEPABLE) == 0)) 1011 printf( 1012 "lock order reversal: (sleepable after non-sleepable)\n"); 1013 else if ((lock1->li_lock->lo_flags & LO_SLEEPABLE) == 0 1014 && lock == &Giant.mtx_object) 1015 printf( 1016 "lock order reversal: (Giant after non-sleepable)\n"); 1017 else 1018 printf("lock order reversal:\n"); 1019 /* 1020 * Try to locate an earlier lock with 1021 * witness w in our list. 1022 */ 1023 do { 1024 lock2 = &lle->ll_children[i]; 1025 MPASS(lock2->li_lock != NULL); 1026 if (lock2->li_lock->lo_witness == w) 1027 break; 1028 if (i == 0 && lle->ll_next != NULL) { 1029 lle = lle->ll_next; 1030 i = lle->ll_count - 1; 1031 MPASS(i >= 0 && i < LOCK_NCHILDREN); 1032 } else 1033 i--; 1034 } while (i >= 0); 1035 if (i < 0) { 1036 printf(" 1st %p %s (%s) @ %s:%d\n", 1037 lock1->li_lock, lock1->li_lock->lo_name, 1038 lock1->li_lock->lo_type, lock1->li_file, 1039 lock1->li_line); 1040 printf(" 2nd %p %s (%s) @ %s:%d\n", lock, 1041 lock->lo_name, lock->lo_type, file, line); 1042 } else { 1043 printf(" 1st %p %s (%s) @ %s:%d\n", 1044 lock2->li_lock, lock2->li_lock->lo_name, 1045 lock2->li_lock->lo_type, lock2->li_file, 1046 lock2->li_line); 1047 printf(" 2nd %p %s (%s) @ %s:%d\n", 1048 lock1->li_lock, lock1->li_lock->lo_name, 1049 lock1->li_lock->lo_type, lock1->li_file, 1050 lock1->li_line); 1051 printf(" 3rd %p %s (%s) @ %s:%d\n", lock, 1052 lock->lo_name, lock->lo_type, file, line); 1053 } 1054 #ifdef KDB 1055 goto debugger; 1056 #else 1057 return; 1058 #endif 1059 } 1060 } 1061 lock1 = &(*lock_list)->ll_children[(*lock_list)->ll_count - 1]; 1062 /* 1063 * If requested, build a new lock order. However, don't build a new 1064 * relationship between a sleepable lock and Giant if it is in the 1065 * wrong direction. The correct lock order is that sleepable locks 1066 * always come before Giant. 1067 */ 1068 if (flags & LOP_NEWORDER && 1069 !(lock1->li_lock == &Giant.mtx_object && 1070 (lock->lo_flags & LO_SLEEPABLE) != 0)) { 1071 CTR3(KTR_WITNESS, "%s: adding %s as a child of %s", __func__, 1072 lock->lo_type, lock1->li_lock->lo_type); 1073 if (!itismychild(lock1->li_lock->lo_witness, w)) 1074 /* Witness is dead. */ 1075 return; 1076 } 1077 mtx_unlock_spin(&w_mtx); 1078 return; 1079 1080 #ifdef KDB 1081 debugger: 1082 if (witness_trace) 1083 kdb_backtrace(); 1084 if (witness_kdb) 1085 kdb_enter(__func__); 1086 #endif 1087 } 1088 1089 void 1090 witness_lock(struct lock_object *lock, int flags, const char *file, int line) 1091 { 1092 struct lock_list_entry **lock_list, *lle; 1093 struct lock_instance *instance; 1094 struct witness *w; 1095 struct thread *td; 1096 1097 if (witness_cold || witness_watch == 0 || lock->lo_witness == NULL || 1098 panicstr != NULL) 1099 return; 1100 w = lock->lo_witness; 1101 td = curthread; 1102 file = fixup_filename(file); 1103 1104 /* Determine lock list for this lock. */ 1105 if (lock->lo_class->lc_flags & LC_SLEEPLOCK) 1106 lock_list = &td->td_sleeplocks; 1107 else 1108 lock_list = PCPU_PTR(spinlocks); 1109 1110 /* Check to see if we are recursing on a lock we already own. */ 1111 instance = find_instance(*lock_list, lock); 1112 if (instance != NULL) { 1113 instance->li_flags++; 1114 CTR4(KTR_WITNESS, "%s: pid %d recursed on %s r=%d", __func__, 1115 td->td_proc->p_pid, lock->lo_name, 1116 instance->li_flags & LI_RECURSEMASK); 1117 instance->li_file = file; 1118 instance->li_line = line; 1119 return; 1120 } 1121 1122 /* Update per-witness last file and line acquire. */ 1123 w->w_file = file; 1124 w->w_line = line; 1125 1126 /* Find the next open lock instance in the list and fill it. */ 1127 lle = *lock_list; 1128 if (lle == NULL || lle->ll_count == LOCK_NCHILDREN) { 1129 lle = witness_lock_list_get(); 1130 if (lle == NULL) 1131 return; 1132 lle->ll_next = *lock_list; 1133 CTR3(KTR_WITNESS, "%s: pid %d added lle %p", __func__, 1134 td->td_proc->p_pid, lle); 1135 *lock_list = lle; 1136 } 1137 instance = &lle->ll_children[lle->ll_count++]; 1138 instance->li_lock = lock; 1139 instance->li_line = line; 1140 instance->li_file = file; 1141 if ((flags & LOP_EXCLUSIVE) != 0) 1142 instance->li_flags = LI_EXCLUSIVE; 1143 else 1144 instance->li_flags = 0; 1145 CTR4(KTR_WITNESS, "%s: pid %d added %s as lle[%d]", __func__, 1146 td->td_proc->p_pid, lock->lo_name, lle->ll_count - 1); 1147 } 1148 1149 void 1150 witness_upgrade(struct lock_object *lock, int flags, const char *file, int line) 1151 { 1152 struct lock_instance *instance; 1153 struct lock_class *class; 1154 1155 KASSERT(!witness_cold, ("%s: witness_cold", __func__)); 1156 if (lock->lo_witness == NULL || witness_watch == 0 || panicstr != NULL) 1157 return; 1158 class = lock->lo_class; 1159 file = fixup_filename(file); 1160 if ((lock->lo_flags & LO_UPGRADABLE) == 0) 1161 panic("upgrade of non-upgradable lock (%s) %s @ %s:%d", 1162 class->lc_name, lock->lo_name, file, line); 1163 if ((flags & LOP_TRYLOCK) == 0) 1164 panic("non-try upgrade of lock (%s) %s @ %s:%d", class->lc_name, 1165 lock->lo_name, file, line); 1166 if ((lock->lo_class->lc_flags & LC_SLEEPLOCK) == 0) 1167 panic("upgrade of non-sleep lock (%s) %s @ %s:%d", 1168 class->lc_name, lock->lo_name, file, line); 1169 instance = find_instance(curthread->td_sleeplocks, lock); 1170 if (instance == NULL) 1171 panic("upgrade of unlocked lock (%s) %s @ %s:%d", 1172 class->lc_name, lock->lo_name, file, line); 1173 if ((instance->li_flags & LI_EXCLUSIVE) != 0) 1174 panic("upgrade of exclusive lock (%s) %s @ %s:%d", 1175 class->lc_name, lock->lo_name, file, line); 1176 if ((instance->li_flags & LI_RECURSEMASK) != 0) 1177 panic("upgrade of recursed lock (%s) %s r=%d @ %s:%d", 1178 class->lc_name, lock->lo_name, 1179 instance->li_flags & LI_RECURSEMASK, file, line); 1180 instance->li_flags |= LI_EXCLUSIVE; 1181 } 1182 1183 void 1184 witness_downgrade(struct lock_object *lock, int flags, const char *file, 1185 int line) 1186 { 1187 struct lock_instance *instance; 1188 struct lock_class *class; 1189 1190 KASSERT(!witness_cold, ("%s: witness_cold", __func__)); 1191 if (lock->lo_witness == NULL || witness_watch == 0 || panicstr != NULL) 1192 return; 1193 class = lock->lo_class; 1194 file = fixup_filename(file); 1195 if ((lock->lo_flags & LO_UPGRADABLE) == 0) 1196 panic("downgrade of non-upgradable lock (%s) %s @ %s:%d", 1197 class->lc_name, lock->lo_name, file, line); 1198 if ((lock->lo_class->lc_flags & LC_SLEEPLOCK) == 0) 1199 panic("downgrade of non-sleep lock (%s) %s @ %s:%d", 1200 class->lc_name, lock->lo_name, file, line); 1201 instance = find_instance(curthread->td_sleeplocks, lock); 1202 if (instance == NULL) 1203 panic("downgrade of unlocked lock (%s) %s @ %s:%d", 1204 class->lc_name, lock->lo_name, file, line); 1205 if ((instance->li_flags & LI_EXCLUSIVE) == 0) 1206 panic("downgrade of shared lock (%s) %s @ %s:%d", 1207 class->lc_name, lock->lo_name, file, line); 1208 if ((instance->li_flags & LI_RECURSEMASK) != 0) 1209 panic("downgrade of recursed lock (%s) %s r=%d @ %s:%d", 1210 class->lc_name, lock->lo_name, 1211 instance->li_flags & LI_RECURSEMASK, file, line); 1212 instance->li_flags &= ~LI_EXCLUSIVE; 1213 } 1214 1215 void 1216 witness_unlock(struct lock_object *lock, int flags, const char *file, int line) 1217 { 1218 struct lock_list_entry **lock_list, *lle; 1219 struct lock_instance *instance; 1220 struct lock_class *class; 1221 struct thread *td; 1222 register_t s; 1223 int i, j; 1224 1225 if (witness_cold || witness_watch == 0 || lock->lo_witness == NULL || 1226 panicstr != NULL) 1227 return; 1228 td = curthread; 1229 class = lock->lo_class; 1230 file = fixup_filename(file); 1231 1232 /* Find lock instance associated with this lock. */ 1233 if (class->lc_flags & LC_SLEEPLOCK) 1234 lock_list = &td->td_sleeplocks; 1235 else 1236 lock_list = PCPU_PTR(spinlocks); 1237 for (; *lock_list != NULL; lock_list = &(*lock_list)->ll_next) 1238 for (i = 0; i < (*lock_list)->ll_count; i++) { 1239 instance = &(*lock_list)->ll_children[i]; 1240 if (instance->li_lock == lock) 1241 goto found; 1242 } 1243 panic("lock (%s) %s not locked @ %s:%d", class->lc_name, lock->lo_name, 1244 file, line); 1245 found: 1246 1247 /* First, check for shared/exclusive mismatches. */ 1248 if ((instance->li_flags & LI_EXCLUSIVE) != 0 && 1249 (flags & LOP_EXCLUSIVE) == 0) { 1250 printf("shared unlock of (%s) %s @ %s:%d\n", class->lc_name, 1251 lock->lo_name, file, line); 1252 printf("while exclusively locked from %s:%d\n", 1253 instance->li_file, instance->li_line); 1254 panic("excl->ushare"); 1255 } 1256 if ((instance->li_flags & LI_EXCLUSIVE) == 0 && 1257 (flags & LOP_EXCLUSIVE) != 0) { 1258 printf("exclusive unlock of (%s) %s @ %s:%d\n", class->lc_name, 1259 lock->lo_name, file, line); 1260 printf("while share locked from %s:%d\n", instance->li_file, 1261 instance->li_line); 1262 panic("share->uexcl"); 1263 } 1264 1265 /* If we are recursed, unrecurse. */ 1266 if ((instance->li_flags & LI_RECURSEMASK) > 0) { 1267 CTR4(KTR_WITNESS, "%s: pid %d unrecursed on %s r=%d", __func__, 1268 td->td_proc->p_pid, instance->li_lock->lo_name, 1269 instance->li_flags); 1270 instance->li_flags--; 1271 return; 1272 } 1273 1274 /* Otherwise, remove this item from the list. */ 1275 s = intr_disable(); 1276 CTR4(KTR_WITNESS, "%s: pid %d removed %s from lle[%d]", __func__, 1277 td->td_proc->p_pid, instance->li_lock->lo_name, 1278 (*lock_list)->ll_count - 1); 1279 for (j = i; j < (*lock_list)->ll_count - 1; j++) 1280 (*lock_list)->ll_children[j] = 1281 (*lock_list)->ll_children[j + 1]; 1282 (*lock_list)->ll_count--; 1283 intr_restore(s); 1284 1285 /* If this lock list entry is now empty, free it. */ 1286 if ((*lock_list)->ll_count == 0) { 1287 lle = *lock_list; 1288 *lock_list = lle->ll_next; 1289 CTR3(KTR_WITNESS, "%s: pid %d removed lle %p", __func__, 1290 td->td_proc->p_pid, lle); 1291 witness_lock_list_free(lle); 1292 } 1293 } 1294 1295 /* 1296 * Warn if any locks other than 'lock' are held. Flags can be passed in to 1297 * exempt Giant and sleepable locks from the checks as well. If any 1298 * non-exempt locks are held, then a supplied message is printed to the 1299 * console along with a list of the offending locks. If indicated in the 1300 * flags then a failure results in a panic as well. 1301 */ 1302 int 1303 witness_warn(int flags, struct lock_object *lock, const char *fmt, ...) 1304 { 1305 struct lock_list_entry *lle; 1306 struct lock_instance *lock1; 1307 struct thread *td; 1308 va_list ap; 1309 int i, n; 1310 1311 if (witness_cold || witness_watch == 0 || panicstr != NULL) 1312 return (0); 1313 n = 0; 1314 td = curthread; 1315 for (lle = td->td_sleeplocks; lle != NULL; lle = lle->ll_next) 1316 for (i = lle->ll_count - 1; i >= 0; i--) { 1317 lock1 = &lle->ll_children[i]; 1318 if (lock1->li_lock == lock) 1319 continue; 1320 if (flags & WARN_GIANTOK && 1321 lock1->li_lock == &Giant.mtx_object) 1322 continue; 1323 if (flags & WARN_SLEEPOK && 1324 (lock1->li_lock->lo_flags & LO_SLEEPABLE) != 0) 1325 continue; 1326 if (n == 0) { 1327 va_start(ap, fmt); 1328 vprintf(fmt, ap); 1329 va_end(ap); 1330 printf(" with the following"); 1331 if (flags & WARN_SLEEPOK) 1332 printf(" non-sleepable"); 1333 printf(" locks held:\n"); 1334 } 1335 n++; 1336 witness_list_lock(lock1); 1337 } 1338 if (PCPU_GET(spinlocks) != NULL) { 1339 /* 1340 * Since we already hold a spinlock preemption is 1341 * already blocked. 1342 */ 1343 if (n == 0) { 1344 va_start(ap, fmt); 1345 vprintf(fmt, ap); 1346 va_end(ap); 1347 printf(" with the following"); 1348 if (flags & WARN_SLEEPOK) 1349 printf(" non-sleepable"); 1350 printf(" locks held:\n"); 1351 } 1352 n += witness_list_locks(PCPU_PTR(spinlocks)); 1353 } 1354 if (flags & WARN_PANIC && n) 1355 panic("witness_warn"); 1356 #ifdef KDB 1357 else if (witness_kdb && n) 1358 kdb_enter(__func__); 1359 else if (witness_trace && n) 1360 kdb_backtrace(); 1361 #endif 1362 return (n); 1363 } 1364 1365 const char * 1366 witness_file(struct lock_object *lock) 1367 { 1368 struct witness *w; 1369 1370 if (witness_cold || witness_watch == 0 || lock->lo_witness == NULL) 1371 return ("?"); 1372 w = lock->lo_witness; 1373 return (w->w_file); 1374 } 1375 1376 int 1377 witness_line(struct lock_object *lock) 1378 { 1379 struct witness *w; 1380 1381 if (witness_cold || witness_watch == 0 || lock->lo_witness == NULL) 1382 return (0); 1383 w = lock->lo_witness; 1384 return (w->w_line); 1385 } 1386 1387 static struct witness * 1388 enroll(const char *description, struct lock_class *lock_class) 1389 { 1390 struct witness *w; 1391 1392 if (witness_watch == 0 || panicstr != NULL) 1393 return (NULL); 1394 if ((lock_class->lc_flags & LC_SPINLOCK) && witness_skipspin) 1395 return (NULL); 1396 mtx_lock_spin(&w_mtx); 1397 STAILQ_FOREACH(w, &w_all, w_list) { 1398 if (w->w_name == description || (w->w_refcount > 0 && 1399 strcmp(description, w->w_name) == 0)) { 1400 w->w_refcount++; 1401 mtx_unlock_spin(&w_mtx); 1402 if (lock_class != w->w_class) 1403 panic( 1404 "lock (%s) %s does not match earlier (%s) lock", 1405 description, lock_class->lc_name, 1406 w->w_class->lc_name); 1407 return (w); 1408 } 1409 } 1410 if ((w = witness_get()) == NULL) 1411 goto out; 1412 w->w_name = description; 1413 w->w_class = lock_class; 1414 w->w_refcount = 1; 1415 STAILQ_INSERT_HEAD(&w_all, w, w_list); 1416 if (lock_class->lc_flags & LC_SPINLOCK) { 1417 STAILQ_INSERT_HEAD(&w_spin, w, w_typelist); 1418 w_spin_cnt++; 1419 } else if (lock_class->lc_flags & LC_SLEEPLOCK) { 1420 STAILQ_INSERT_HEAD(&w_sleep, w, w_typelist); 1421 w_sleep_cnt++; 1422 } else { 1423 mtx_unlock_spin(&w_mtx); 1424 panic("lock class %s is not sleep or spin", 1425 lock_class->lc_name); 1426 } 1427 mtx_unlock_spin(&w_mtx); 1428 out: 1429 /* 1430 * We issue a warning for any spin locks not defined in the static 1431 * order list as a way to discourage their use (folks should really 1432 * be using non-spin mutexes most of the time). However, several 1433 * 3rd part device drivers use spin locks because that is all they 1434 * have available on Windows and Linux and they think that normal 1435 * mutexes are insufficient. 1436 */ 1437 if ((lock_class->lc_flags & LC_SPINLOCK) && witness_spin_warn) 1438 printf("WITNESS: spin lock %s not in order list\n", 1439 description); 1440 return (w); 1441 } 1442 1443 /* Don't let the door bang you on the way out... */ 1444 static int 1445 depart(struct witness *w) 1446 { 1447 struct witness_child_list_entry *wcl, *nwcl; 1448 struct witness_list *list; 1449 struct witness *parent; 1450 1451 MPASS(w->w_refcount == 0); 1452 if (w->w_class->lc_flags & LC_SLEEPLOCK) { 1453 list = &w_sleep; 1454 w_sleep_cnt--; 1455 } else { 1456 list = &w_spin; 1457 w_spin_cnt--; 1458 } 1459 /* 1460 * First, we run through the entire tree looking for any 1461 * witnesses that the outgoing witness is a child of. For 1462 * each parent that we find, we reparent all the direct 1463 * children of the outgoing witness to its parent. 1464 */ 1465 STAILQ_FOREACH(parent, list, w_typelist) { 1466 if (!isitmychild(parent, w)) 1467 continue; 1468 removechild(parent, w); 1469 } 1470 1471 /* 1472 * Now we go through and free up the child list of the 1473 * outgoing witness. 1474 */ 1475 for (wcl = w->w_children; wcl != NULL; wcl = nwcl) { 1476 nwcl = wcl->wcl_next; 1477 w_child_cnt--; 1478 witness_child_free(wcl); 1479 } 1480 1481 /* 1482 * Detach from various lists and free. 1483 */ 1484 STAILQ_REMOVE(list, w, witness, w_typelist); 1485 STAILQ_REMOVE(&w_all, w, witness, w_list); 1486 witness_free(w); 1487 1488 return (1); 1489 } 1490 1491 /* 1492 * Add "child" as a direct child of "parent". Returns false if 1493 * we fail due to out of memory. 1494 */ 1495 static int 1496 insertchild(struct witness *parent, struct witness *child) 1497 { 1498 struct witness_child_list_entry **wcl; 1499 1500 MPASS(child != NULL && parent != NULL); 1501 1502 /* 1503 * Insert "child" after "parent" 1504 */ 1505 wcl = &parent->w_children; 1506 while (*wcl != NULL && (*wcl)->wcl_count == WITNESS_NCHILDREN) 1507 wcl = &(*wcl)->wcl_next; 1508 if (*wcl == NULL) { 1509 *wcl = witness_child_get(); 1510 if (*wcl == NULL) 1511 return (0); 1512 w_child_cnt++; 1513 } 1514 (*wcl)->wcl_children[(*wcl)->wcl_count++] = child; 1515 1516 return (1); 1517 } 1518 1519 1520 static int 1521 itismychild(struct witness *parent, struct witness *child) 1522 { 1523 struct witness_list *list; 1524 1525 MPASS(child != NULL && parent != NULL); 1526 if ((parent->w_class->lc_flags & (LC_SLEEPLOCK | LC_SPINLOCK)) != 1527 (child->w_class->lc_flags & (LC_SLEEPLOCK | LC_SPINLOCK))) 1528 panic( 1529 "%s: parent (%s) and child (%s) are not the same lock type", 1530 __func__, parent->w_class->lc_name, 1531 child->w_class->lc_name); 1532 1533 if (!insertchild(parent, child)) 1534 return (0); 1535 1536 if (parent->w_class->lc_flags & LC_SLEEPLOCK) 1537 list = &w_sleep; 1538 else 1539 list = &w_spin; 1540 return (1); 1541 } 1542 1543 static void 1544 removechild(struct witness *parent, struct witness *child) 1545 { 1546 struct witness_child_list_entry **wcl, *wcl1; 1547 int i; 1548 1549 for (wcl = &parent->w_children; *wcl != NULL; wcl = &(*wcl)->wcl_next) 1550 for (i = 0; i < (*wcl)->wcl_count; i++) 1551 if ((*wcl)->wcl_children[i] == child) 1552 goto found; 1553 return; 1554 found: 1555 (*wcl)->wcl_count--; 1556 if ((*wcl)->wcl_count > i) 1557 (*wcl)->wcl_children[i] = 1558 (*wcl)->wcl_children[(*wcl)->wcl_count]; 1559 MPASS((*wcl)->wcl_children[i] != NULL); 1560 if ((*wcl)->wcl_count != 0) 1561 return; 1562 wcl1 = *wcl; 1563 *wcl = wcl1->wcl_next; 1564 w_child_cnt--; 1565 witness_child_free(wcl1); 1566 } 1567 1568 static int 1569 isitmychild(struct witness *parent, struct witness *child) 1570 { 1571 struct witness_child_list_entry *wcl; 1572 int i; 1573 1574 for (wcl = parent->w_children; wcl != NULL; wcl = wcl->wcl_next) { 1575 for (i = 0; i < wcl->wcl_count; i++) { 1576 if (wcl->wcl_children[i] == child) 1577 return (1); 1578 } 1579 } 1580 return (0); 1581 } 1582 1583 static int 1584 isitmydescendant(struct witness *parent, struct witness *child) 1585 { 1586 struct witness_child_list_entry *wcl; 1587 int i, j; 1588 1589 if (isitmychild(parent, child)) 1590 return (1); 1591 j = 0; 1592 for (wcl = parent->w_children; wcl != NULL; wcl = wcl->wcl_next) { 1593 MPASS(j < 1000); 1594 for (i = 0; i < wcl->wcl_count; i++) { 1595 if (isitmydescendant(wcl->wcl_children[i], child)) 1596 return (1); 1597 } 1598 j++; 1599 } 1600 return (0); 1601 } 1602 1603 #ifdef BLESSING 1604 static int 1605 blessed(struct witness *w1, struct witness *w2) 1606 { 1607 int i; 1608 struct witness_blessed *b; 1609 1610 for (i = 0; i < blessed_count; i++) { 1611 b = &blessed_list[i]; 1612 if (strcmp(w1->w_name, b->b_lock1) == 0) { 1613 if (strcmp(w2->w_name, b->b_lock2) == 0) 1614 return (1); 1615 continue; 1616 } 1617 if (strcmp(w1->w_name, b->b_lock2) == 0) 1618 if (strcmp(w2->w_name, b->b_lock1) == 0) 1619 return (1); 1620 } 1621 return (0); 1622 } 1623 #endif 1624 1625 static struct witness * 1626 witness_get(void) 1627 { 1628 struct witness *w; 1629 1630 if (witness_watch == 0) { 1631 mtx_unlock_spin(&w_mtx); 1632 return (NULL); 1633 } 1634 if (STAILQ_EMPTY(&w_free)) { 1635 witness_watch = 0; 1636 mtx_unlock_spin(&w_mtx); 1637 printf("%s: witness exhausted\n", __func__); 1638 return (NULL); 1639 } 1640 w = STAILQ_FIRST(&w_free); 1641 STAILQ_REMOVE_HEAD(&w_free, w_list); 1642 w_free_cnt--; 1643 bzero(w, sizeof(*w)); 1644 return (w); 1645 } 1646 1647 static void 1648 witness_free(struct witness *w) 1649 { 1650 1651 STAILQ_INSERT_HEAD(&w_free, w, w_list); 1652 w_free_cnt++; 1653 } 1654 1655 static struct witness_child_list_entry * 1656 witness_child_get(void) 1657 { 1658 struct witness_child_list_entry *wcl; 1659 1660 if (witness_watch == 0) { 1661 mtx_unlock_spin(&w_mtx); 1662 return (NULL); 1663 } 1664 wcl = w_child_free; 1665 if (wcl == NULL) { 1666 witness_watch = 0; 1667 mtx_unlock_spin(&w_mtx); 1668 printf("%s: witness exhausted\n", __func__); 1669 return (NULL); 1670 } 1671 w_child_free = wcl->wcl_next; 1672 w_child_free_cnt--; 1673 bzero(wcl, sizeof(*wcl)); 1674 return (wcl); 1675 } 1676 1677 static void 1678 witness_child_free(struct witness_child_list_entry *wcl) 1679 { 1680 1681 wcl->wcl_next = w_child_free; 1682 w_child_free = wcl; 1683 w_child_free_cnt++; 1684 } 1685 1686 static struct lock_list_entry * 1687 witness_lock_list_get(void) 1688 { 1689 struct lock_list_entry *lle; 1690 1691 if (witness_watch == 0) 1692 return (NULL); 1693 mtx_lock_spin(&w_mtx); 1694 lle = w_lock_list_free; 1695 if (lle == NULL) { 1696 witness_watch = 0; 1697 mtx_unlock_spin(&w_mtx); 1698 printf("%s: witness exhausted\n", __func__); 1699 return (NULL); 1700 } 1701 w_lock_list_free = lle->ll_next; 1702 mtx_unlock_spin(&w_mtx); 1703 bzero(lle, sizeof(*lle)); 1704 return (lle); 1705 } 1706 1707 static void 1708 witness_lock_list_free(struct lock_list_entry *lle) 1709 { 1710 1711 mtx_lock_spin(&w_mtx); 1712 lle->ll_next = w_lock_list_free; 1713 w_lock_list_free = lle; 1714 mtx_unlock_spin(&w_mtx); 1715 } 1716 1717 static struct lock_instance * 1718 find_instance(struct lock_list_entry *lock_list, struct lock_object *lock) 1719 { 1720 struct lock_list_entry *lle; 1721 struct lock_instance *instance; 1722 int i; 1723 1724 for (lle = lock_list; lle != NULL; lle = lle->ll_next) 1725 for (i = lle->ll_count - 1; i >= 0; i--) { 1726 instance = &lle->ll_children[i]; 1727 if (instance->li_lock == lock) 1728 return (instance); 1729 } 1730 return (NULL); 1731 } 1732 1733 static void 1734 witness_list_lock(struct lock_instance *instance) 1735 { 1736 struct lock_object *lock; 1737 1738 lock = instance->li_lock; 1739 printf("%s %s %s", (instance->li_flags & LI_EXCLUSIVE) != 0 ? 1740 "exclusive" : "shared", lock->lo_class->lc_name, lock->lo_name); 1741 if (lock->lo_type != lock->lo_name) 1742 printf(" (%s)", lock->lo_type); 1743 printf(" r = %d (%p) locked @ %s:%d\n", 1744 instance->li_flags & LI_RECURSEMASK, lock, instance->li_file, 1745 instance->li_line); 1746 } 1747 1748 #ifdef DDB 1749 static int 1750 witness_thread_has_locks(struct thread *td) 1751 { 1752 1753 return (td->td_sleeplocks != NULL); 1754 } 1755 1756 static int 1757 witness_proc_has_locks(struct proc *p) 1758 { 1759 struct thread *td; 1760 1761 FOREACH_THREAD_IN_PROC(p, td) { 1762 if (witness_thread_has_locks(td)) 1763 return (1); 1764 } 1765 return (0); 1766 } 1767 #endif 1768 1769 int 1770 witness_list_locks(struct lock_list_entry **lock_list) 1771 { 1772 struct lock_list_entry *lle; 1773 int i, nheld; 1774 1775 nheld = 0; 1776 for (lle = *lock_list; lle != NULL; lle = lle->ll_next) 1777 for (i = lle->ll_count - 1; i >= 0; i--) { 1778 witness_list_lock(&lle->ll_children[i]); 1779 nheld++; 1780 } 1781 return (nheld); 1782 } 1783 1784 /* 1785 * This is a bit risky at best. We call this function when we have timed 1786 * out acquiring a spin lock, and we assume that the other CPU is stuck 1787 * with this lock held. So, we go groveling around in the other CPU's 1788 * per-cpu data to try to find the lock instance for this spin lock to 1789 * see when it was last acquired. 1790 */ 1791 void 1792 witness_display_spinlock(struct lock_object *lock, struct thread *owner) 1793 { 1794 struct lock_instance *instance; 1795 struct pcpu *pc; 1796 1797 if (owner->td_critnest == 0 || owner->td_oncpu == NOCPU) 1798 return; 1799 pc = pcpu_find(owner->td_oncpu); 1800 instance = find_instance(pc->pc_spinlocks, lock); 1801 if (instance != NULL) 1802 witness_list_lock(instance); 1803 } 1804 1805 void 1806 witness_save(struct lock_object *lock, const char **filep, int *linep) 1807 { 1808 struct lock_instance *instance; 1809 1810 KASSERT(!witness_cold, ("%s: witness_cold", __func__)); 1811 if (lock->lo_witness == NULL || witness_watch == 0 || panicstr != NULL) 1812 return; 1813 if ((lock->lo_class->lc_flags & LC_SLEEPLOCK) == 0) 1814 panic("%s: lock (%s) %s is not a sleep lock", __func__, 1815 lock->lo_class->lc_name, lock->lo_name); 1816 instance = find_instance(curthread->td_sleeplocks, lock); 1817 if (instance == NULL) 1818 panic("%s: lock (%s) %s not locked", __func__, 1819 lock->lo_class->lc_name, lock->lo_name); 1820 *filep = instance->li_file; 1821 *linep = instance->li_line; 1822 } 1823 1824 void 1825 witness_restore(struct lock_object *lock, const char *file, int line) 1826 { 1827 struct lock_instance *instance; 1828 1829 KASSERT(!witness_cold, ("%s: witness_cold", __func__)); 1830 if (lock->lo_witness == NULL || witness_watch == 0 || panicstr != NULL) 1831 return; 1832 if ((lock->lo_class->lc_flags & LC_SLEEPLOCK) == 0) 1833 panic("%s: lock (%s) %s is not a sleep lock", __func__, 1834 lock->lo_class->lc_name, lock->lo_name); 1835 instance = find_instance(curthread->td_sleeplocks, lock); 1836 if (instance == NULL) 1837 panic("%s: lock (%s) %s not locked", __func__, 1838 lock->lo_class->lc_name, lock->lo_name); 1839 lock->lo_witness->w_file = file; 1840 lock->lo_witness->w_line = line; 1841 instance->li_file = file; 1842 instance->li_line = line; 1843 } 1844 1845 void 1846 witness_assert(struct lock_object *lock, int flags, const char *file, int line) 1847 { 1848 #ifdef INVARIANT_SUPPORT 1849 struct lock_instance *instance; 1850 1851 if (lock->lo_witness == NULL || witness_watch == 0 || panicstr != NULL) 1852 return; 1853 if ((lock->lo_class->lc_flags & LC_SLEEPLOCK) != 0) 1854 instance = find_instance(curthread->td_sleeplocks, lock); 1855 else if ((lock->lo_class->lc_flags & LC_SPINLOCK) != 0) 1856 instance = find_instance(PCPU_GET(spinlocks), lock); 1857 else { 1858 panic("Lock (%s) %s is not sleep or spin!", 1859 lock->lo_class->lc_name, lock->lo_name); 1860 } 1861 file = fixup_filename(file); 1862 switch (flags) { 1863 case LA_UNLOCKED: 1864 if (instance != NULL) 1865 panic("Lock (%s) %s locked @ %s:%d.", 1866 lock->lo_class->lc_name, lock->lo_name, file, line); 1867 break; 1868 case LA_LOCKED: 1869 case LA_LOCKED | LA_RECURSED: 1870 case LA_LOCKED | LA_NOTRECURSED: 1871 case LA_SLOCKED: 1872 case LA_SLOCKED | LA_RECURSED: 1873 case LA_SLOCKED | LA_NOTRECURSED: 1874 case LA_XLOCKED: 1875 case LA_XLOCKED | LA_RECURSED: 1876 case LA_XLOCKED | LA_NOTRECURSED: 1877 if (instance == NULL) { 1878 panic("Lock (%s) %s not locked @ %s:%d.", 1879 lock->lo_class->lc_name, lock->lo_name, file, line); 1880 break; 1881 } 1882 if ((flags & LA_XLOCKED) != 0 && 1883 (instance->li_flags & LI_EXCLUSIVE) == 0) 1884 panic("Lock (%s) %s not exclusively locked @ %s:%d.", 1885 lock->lo_class->lc_name, lock->lo_name, file, line); 1886 if ((flags & LA_SLOCKED) != 0 && 1887 (instance->li_flags & LI_EXCLUSIVE) != 0) 1888 panic("Lock (%s) %s exclusively locked @ %s:%d.", 1889 lock->lo_class->lc_name, lock->lo_name, file, line); 1890 if ((flags & LA_RECURSED) != 0 && 1891 (instance->li_flags & LI_RECURSEMASK) == 0) 1892 panic("Lock (%s) %s not recursed @ %s:%d.", 1893 lock->lo_class->lc_name, lock->lo_name, file, line); 1894 if ((flags & LA_NOTRECURSED) != 0 && 1895 (instance->li_flags & LI_RECURSEMASK) != 0) 1896 panic("Lock (%s) %s recursed @ %s:%d.", 1897 lock->lo_class->lc_name, lock->lo_name, file, line); 1898 break; 1899 default: 1900 panic("Invalid lock assertion at %s:%d.", file, line); 1901 1902 } 1903 #endif /* INVARIANT_SUPPORT */ 1904 } 1905 1906 #ifdef DDB 1907 static void 1908 witness_list(struct thread *td) 1909 { 1910 1911 KASSERT(!witness_cold, ("%s: witness_cold", __func__)); 1912 KASSERT(kdb_active, ("%s: not in the debugger", __func__)); 1913 1914 if (witness_watch == 0) 1915 return; 1916 1917 witness_list_locks(&td->td_sleeplocks); 1918 1919 /* 1920 * We only handle spinlocks if td == curthread. This is somewhat broken 1921 * if td is currently executing on some other CPU and holds spin locks 1922 * as we won't display those locks. If we had a MI way of getting 1923 * the per-cpu data for a given cpu then we could use 1924 * td->td_oncpu to get the list of spinlocks for this thread 1925 * and "fix" this. 1926 * 1927 * That still wouldn't really fix this unless we locked sched_lock 1928 * or stopped the other CPU to make sure it wasn't changing the list 1929 * out from under us. It is probably best to just not try to handle 1930 * threads on other CPU's for now. 1931 */ 1932 if (td == curthread && PCPU_GET(spinlocks) != NULL) 1933 witness_list_locks(PCPU_PTR(spinlocks)); 1934 } 1935 1936 DB_SHOW_COMMAND(locks, db_witness_list) 1937 { 1938 struct thread *td; 1939 pid_t pid; 1940 struct proc *p; 1941 1942 if (have_addr) { 1943 pid = (addr % 16) + ((addr >> 4) % 16) * 10 + 1944 ((addr >> 8) % 16) * 100 + ((addr >> 12) % 16) * 1000 + 1945 ((addr >> 16) % 16) * 10000; 1946 /* sx_slock(&allproc_lock); */ 1947 FOREACH_PROC_IN_SYSTEM(p) { 1948 if (p->p_pid == pid) 1949 break; 1950 } 1951 /* sx_sunlock(&allproc_lock); */ 1952 if (p == NULL) { 1953 db_printf("pid %d not found\n", pid); 1954 return; 1955 } 1956 FOREACH_THREAD_IN_PROC(p, td) { 1957 witness_list(td); 1958 } 1959 } else { 1960 td = curthread; 1961 witness_list(td); 1962 } 1963 } 1964 1965 DB_SHOW_COMMAND(alllocks, db_witness_list_all) 1966 { 1967 struct thread *td; 1968 struct proc *p; 1969 1970 /* 1971 * It would be nice to list only threads and processes that actually 1972 * held sleep locks, but that information is currently not exported 1973 * by WITNESS. 1974 */ 1975 FOREACH_PROC_IN_SYSTEM(p) { 1976 if (!witness_proc_has_locks(p)) 1977 continue; 1978 FOREACH_THREAD_IN_PROC(p, td) { 1979 if (!witness_thread_has_locks(td)) 1980 continue; 1981 db_printf("Process %d (%s) thread %p (%d)\n", p->p_pid, 1982 p->p_comm, td, td->td_tid); 1983 witness_list(td); 1984 } 1985 } 1986 } 1987 1988 DB_SHOW_COMMAND(witness, db_witness_display) 1989 { 1990 1991 witness_display(db_printf); 1992 } 1993 #endif
Cache object: 0de9b917ecdcbc9dcc8da283f9eaf5bc
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