subr_witness.c revision 74900
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 * $FreeBSD: head/sys/kern/subr_witness.c 74900 2001-03-28 02:40:47Z jhb $ 31 */ 32 33/* 34 * Machine independent bits of mutex implementation and implementation of 35 * `witness' structure & related debugging routines. 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#include "opt_ddb.h" 59#include "opt_witness.h" 60 61#include <sys/param.h> 62#include <sys/bus.h> 63#include <sys/kernel.h> 64#include <sys/malloc.h> 65#include <sys/proc.h> 66#include <sys/sysctl.h> 67#include <sys/systm.h> 68#include <sys/vmmeter.h> 69#include <sys/ktr.h> 70 71#include <machine/atomic.h> 72#include <machine/bus.h> 73#include <machine/clock.h> 74#include <machine/cpu.h> 75 76#include <ddb/ddb.h> 77 78#include <vm/vm.h> 79#include <vm/vm_extern.h> 80 81#include <sys/mutex.h> 82 83/* 84 * The WITNESS-enabled mutex debug structure. 85 */ 86#ifdef WITNESS 87struct mtx_debug { 88 struct witness *mtxd_witness; 89 LIST_ENTRY(mtx) mtxd_held; 90 const char *mtxd_file; 91 int mtxd_line; 92}; 93 94#define mtx_held mtx_debug->mtxd_held 95#define mtx_file mtx_debug->mtxd_file 96#define mtx_line mtx_debug->mtxd_line 97#define mtx_witness mtx_debug->mtxd_witness 98#endif /* WITNESS */ 99 100/* 101 * Internal utility macros. 102 */ 103#define mtx_unowned(m) ((m)->mtx_lock == MTX_UNOWNED) 104 105#define mtx_owner(m) (mtx_unowned((m)) ? NULL \ 106 : (struct proc *)((m)->mtx_lock & MTX_FLAGMASK)) 107 108#define SET_PRIO(p, pri) (p)->p_pri.pri_level = (pri) 109 110/* 111 * Early WITNESS-enabled declarations. 112 */ 113#ifdef WITNESS 114 115/* 116 * Internal WITNESS routines which must be prototyped early. 117 * 118 * XXX: When/if witness code is cleaned up, it would be wise to place all 119 * witness prototyping early in this file. 120 */ 121static void witness_init(struct mtx *, int flag); 122static void witness_destroy(struct mtx *); 123static void witness_display(void(*)(const char *fmt, ...)); 124 125MALLOC_DEFINE(M_WITNESS, "witness", "witness mtx_debug structure"); 126 127/* All mutexes in system (used for debug/panic) */ 128static struct mtx_debug all_mtx_debug = { NULL, {NULL, NULL}, NULL, 0 }; 129 130/* 131 * This global is set to 0 once it becomes safe to use the witness code. 132 */ 133static int witness_cold = 1; 134 135#else /* WITNESS */ 136 137/* XXX XXX XXX 138 * flag++ is sleazoid way of shuting up warning 139 */ 140#define witness_init(m, flag) flag++ 141#define witness_destroy(m) 142#define witness_try_enter(m, t, f, l) 143#endif /* WITNESS */ 144 145/* 146 * All mutex locks in system are kept on the all_mtx list. 147 */ 148static struct mtx all_mtx = { MTX_UNOWNED, 0, 0, 0, "All mutexes queue head", 149 TAILQ_HEAD_INITIALIZER(all_mtx.mtx_blocked), 150 { NULL, NULL }, &all_mtx, &all_mtx, 151#ifdef WITNESS 152 &all_mtx_debug 153#else 154 NULL 155#endif 156 }; 157 158/* 159 * Global variables for book keeping. 160 */ 161static int mtx_cur_cnt; 162static int mtx_max_cnt; 163 164/* 165 * Couple of strings for KTR_LOCK tracing in order to avoid duplicates. 166 */ 167char STR_mtx_lock_slp[] = "GOT (sleep) %s [%p] r=%d at %s:%d"; 168char STR_mtx_unlock_slp[] = "REL (sleep) %s [%p] r=%d at %s:%d"; 169char STR_mtx_lock_spn[] = "GOT (spin) %s [%p] r=%d at %s:%d"; 170char STR_mtx_unlock_spn[] = "REL (spin) %s [%p] r=%d at %s:%d"; 171 172/* 173 * Prototypes for non-exported routines. 174 * 175 * NOTE: Prototypes for witness routines are placed at the bottom of the file. 176 */ 177static void propagate_priority(struct proc *); 178 179static void 180propagate_priority(struct proc *p) 181{ 182 int pri = p->p_pri.pri_level; 183 struct mtx *m = p->p_blocked; 184 185 mtx_assert(&sched_lock, MA_OWNED); 186 for (;;) { 187 struct proc *p1; 188 189 p = mtx_owner(m); 190 191 if (p == NULL) { 192 /* 193 * This really isn't quite right. Really 194 * ought to bump priority of process that 195 * next acquires the mutex. 196 */ 197 MPASS(m->mtx_lock == MTX_CONTESTED); 198 return; 199 } 200 201 MPASS(p->p_magic == P_MAGIC); 202 KASSERT(p->p_stat != SSLEEP, ("sleeping process owns a mutex")); 203 if (p->p_pri.pri_level <= pri) 204 return; 205 206 /* 207 * Bump this process' priority. 208 */ 209 SET_PRIO(p, pri); 210 211 /* 212 * If lock holder is actually running, just bump priority. 213 */ 214 if (p->p_oncpu != NOCPU) { 215 MPASS(p->p_stat == SRUN || p->p_stat == SZOMB); 216 return; 217 } 218 219#ifndef SMP 220 /* 221 * For UP, we check to see if p is curproc (this shouldn't 222 * ever happen however as it would mean we are in a deadlock.) 223 */ 224 KASSERT(p != curproc, ("Deadlock detected")); 225#endif 226 227 /* 228 * If on run queue move to new run queue, and 229 * quit. 230 */ 231 if (p->p_stat == SRUN) { 232 MPASS(p->p_blocked == NULL); 233 remrunqueue(p); 234 setrunqueue(p); 235 return; 236 } 237 238 /* 239 * If we aren't blocked on a mutex, we should be. 240 */ 241 KASSERT(p->p_stat == SMTX, ( 242 "process %d(%s):%d holds %s but isn't blocked on a mutex\n", 243 p->p_pid, p->p_comm, p->p_stat, 244 m->mtx_description)); 245 246 /* 247 * Pick up the mutex that p is blocked on. 248 */ 249 m = p->p_blocked; 250 MPASS(m != NULL); 251 252 /* 253 * Check if the proc needs to be moved up on 254 * the blocked chain 255 */ 256 if (p == TAILQ_FIRST(&m->mtx_blocked)) { 257 continue; 258 } 259 260 p1 = TAILQ_PREV(p, procqueue, p_procq); 261 if (p1->p_pri.pri_level <= pri) { 262 continue; 263 } 264 265 /* 266 * Remove proc from blocked chain and determine where 267 * it should be moved up to. Since we know that p1 has 268 * a lower priority than p, we know that at least one 269 * process in the chain has a lower priority and that 270 * p1 will thus not be NULL after the loop. 271 */ 272 TAILQ_REMOVE(&m->mtx_blocked, p, p_procq); 273 TAILQ_FOREACH(p1, &m->mtx_blocked, p_procq) { 274 MPASS(p1->p_magic == P_MAGIC); 275 if (p1->p_pri.pri_level > pri) 276 break; 277 } 278 279 MPASS(p1 != NULL); 280 TAILQ_INSERT_BEFORE(p1, p, p_procq); 281 CTR4(KTR_LOCK, 282 "propagate_priority: p %p moved before %p on [%p] %s", 283 p, p1, m, m->mtx_description); 284 } 285} 286 287/* 288 * Function versions of the inlined __mtx_* macros. These are used by 289 * modules and can also be called from assembly language if needed. 290 */ 291void 292_mtx_lock_flags(struct mtx *m, int opts, const char *file, int line) 293{ 294 295 __mtx_lock_flags(m, opts, file, line); 296} 297 298void 299_mtx_unlock_flags(struct mtx *m, int opts, const char *file, int line) 300{ 301 302 __mtx_unlock_flags(m, opts, file, line); 303} 304 305void 306_mtx_lock_spin_flags(struct mtx *m, int opts, const char *file, int line) 307{ 308 309 __mtx_lock_spin_flags(m, opts, file, line); 310} 311 312void 313_mtx_unlock_spin_flags(struct mtx *m, int opts, const char *file, int line) 314{ 315 316 __mtx_unlock_spin_flags(m, opts, file, line); 317} 318 319/* 320 * The important part of mtx_trylock{,_flags}() 321 * Tries to acquire lock `m.' We do NOT handle recursion here; we assume that 322 * if we're called, it's because we know we don't already own this lock. 323 */ 324int 325_mtx_trylock(struct mtx *m, int opts, const char *file, int line) 326{ 327 int rval; 328 329 MPASS(curproc != NULL); 330 331 /* 332 * _mtx_trylock does not accept MTX_NOSWITCH option. 333 */ 334 KASSERT((opts & MTX_NOSWITCH) == 0, 335 ("mtx_trylock() called with invalid option flag(s) %d", opts)); 336 337 rval = _obtain_lock(m, curproc); 338 339#ifdef WITNESS 340 if (rval && m->mtx_witness != NULL) { 341 /* 342 * We do not handle recursion in _mtx_trylock; see the 343 * note at the top of the routine. 344 */ 345 KASSERT(!mtx_recursed(m), 346 ("mtx_trylock() called on a recursed mutex")); 347 witness_try_enter(m, (opts | m->mtx_flags), file, line); 348 } 349#endif /* WITNESS */ 350 351 if ((opts & MTX_QUIET) == 0) 352 CTR5(KTR_LOCK, "TRY_LOCK %s [%p] result=%d at %s:%d", 353 m->mtx_description, m, rval, file, line); 354 355 return rval; 356} 357 358/* 359 * _mtx_lock_sleep: the tougher part of acquiring an MTX_DEF lock. 360 * 361 * We call this if the lock is either contested (i.e. we need to go to 362 * sleep waiting for it), or if we need to recurse on it. 363 */ 364void 365_mtx_lock_sleep(struct mtx *m, int opts, const char *file, int line) 366{ 367 struct proc *p = curproc; 368 369 if ((m->mtx_lock & MTX_FLAGMASK) == (uintptr_t)p) { 370 m->mtx_recurse++; 371 atomic_set_ptr(&m->mtx_lock, MTX_RECURSED); 372 if ((opts & MTX_QUIET) == 0) 373 CTR1(KTR_LOCK, "_mtx_lock_sleep: %p recursing", m); 374 return; 375 } 376 377 if ((opts & MTX_QUIET) == 0) 378 CTR4(KTR_LOCK, 379 "_mtx_lock_sleep: %s contested (lock=%p) at %s:%d", 380 m->mtx_description, (void *)m->mtx_lock, file, line); 381 382 while (!_obtain_lock(m, p)) { 383 uintptr_t v; 384 struct proc *p1; 385 386 mtx_lock_spin(&sched_lock); 387 /* 388 * Check if the lock has been released while spinning for 389 * the sched_lock. 390 */ 391 if ((v = m->mtx_lock) == MTX_UNOWNED) { 392 mtx_unlock_spin(&sched_lock); 393 continue; 394 } 395 396 /* 397 * The mutex was marked contested on release. This means that 398 * there are processes blocked on it. 399 */ 400 if (v == MTX_CONTESTED) { 401 p1 = TAILQ_FIRST(&m->mtx_blocked); 402 MPASS(p1 != NULL); 403 m->mtx_lock = (uintptr_t)p | MTX_CONTESTED; 404 405 if (p1->p_pri.pri_level < p->p_pri.pri_level) 406 SET_PRIO(p, p1->p_pri.pri_level); 407 mtx_unlock_spin(&sched_lock); 408 return; 409 } 410 411 /* 412 * If the mutex isn't already contested and a failure occurs 413 * setting the contested bit, the mutex was either released 414 * or the state of the MTX_RECURSED bit changed. 415 */ 416 if ((v & MTX_CONTESTED) == 0 && 417 !atomic_cmpset_ptr(&m->mtx_lock, (void *)v, 418 (void *)(v | MTX_CONTESTED))) { 419 mtx_unlock_spin(&sched_lock); 420 continue; 421 } 422 423 /* 424 * We deffinately must sleep for this lock. 425 */ 426 mtx_assert(m, MA_NOTOWNED); 427 428#ifdef notyet 429 /* 430 * If we're borrowing an interrupted thread's VM context, we 431 * must clean up before going to sleep. 432 */ 433 if (p->p_ithd != NULL) { 434 struct ithd *it = p->p_ithd; 435 436 if (it->it_interrupted) { 437 if ((opts & MTX_QUIET) == 0) 438 CTR2(KTR_LOCK, 439 "_mtx_lock_sleep: %p interrupted %p", 440 it, it->it_interrupted); 441 intr_thd_fixup(it); 442 } 443 } 444#endif 445 446 /* 447 * Put us on the list of threads blocked on this mutex. 448 */ 449 if (TAILQ_EMPTY(&m->mtx_blocked)) { 450 p1 = (struct proc *)(m->mtx_lock & MTX_FLAGMASK); 451 LIST_INSERT_HEAD(&p1->p_contested, m, mtx_contested); 452 TAILQ_INSERT_TAIL(&m->mtx_blocked, p, p_procq); 453 } else { 454 TAILQ_FOREACH(p1, &m->mtx_blocked, p_procq) 455 if (p1->p_pri.pri_level > p->p_pri.pri_level) 456 break; 457 if (p1) 458 TAILQ_INSERT_BEFORE(p1, p, p_procq); 459 else 460 TAILQ_INSERT_TAIL(&m->mtx_blocked, p, p_procq); 461 } 462 463 /* 464 * Save who we're blocked on. 465 */ 466 p->p_blocked = m; 467 p->p_mtxname = m->mtx_description; 468 p->p_stat = SMTX; 469 propagate_priority(p); 470 471 if ((opts & MTX_QUIET) == 0) 472 CTR3(KTR_LOCK, 473 "_mtx_lock_sleep: p %p blocked on [%p] %s", p, m, 474 m->mtx_description); 475 476 mi_switch(); 477 478 if ((opts & MTX_QUIET) == 0) 479 CTR3(KTR_LOCK, 480 "_mtx_lock_sleep: p %p free from blocked on [%p] %s", 481 p, m, m->mtx_description); 482 483 mtx_unlock_spin(&sched_lock); 484 } 485 486 return; 487} 488 489/* 490 * _mtx_lock_spin: the tougher part of acquiring an MTX_SPIN lock. 491 * 492 * This is only called if we need to actually spin for the lock. Recursion 493 * is handled inline. 494 */ 495void 496_mtx_lock_spin(struct mtx *m, int opts, critical_t mtx_crit, const char *file, 497 int line) 498{ 499 int i = 0; 500 501 if ((opts & MTX_QUIET) == 0) 502 CTR1(KTR_LOCK, "_mtx_lock_spin: %p spinning", m); 503 504 for (;;) { 505 if (_obtain_lock(m, curproc)) 506 break; 507 508 while (m->mtx_lock != MTX_UNOWNED) { 509 if (i++ < 1000000) 510 continue; 511 if (i++ < 6000000) 512 DELAY(1); 513#ifdef DDB 514 else if (!db_active) 515#else 516 else 517#endif 518 panic("spin lock %s held by %p for > 5 seconds", 519 m->mtx_description, (void *)m->mtx_lock); 520 } 521 } 522 523 m->mtx_savecrit = mtx_crit; 524 if ((opts & MTX_QUIET) == 0) 525 CTR1(KTR_LOCK, "_mtx_lock_spin: %p spin done", m); 526 527 return; 528} 529 530/* 531 * _mtx_unlock_sleep: the tougher part of releasing an MTX_DEF lock. 532 * 533 * We are only called here if the lock is recursed or contested (i.e. we 534 * need to wake up a blocked thread). 535 */ 536void 537_mtx_unlock_sleep(struct mtx *m, int opts, const char *file, int line) 538{ 539 struct proc *p, *p1; 540 struct mtx *m1; 541 int pri; 542 543 p = curproc; 544 545 if (mtx_recursed(m)) { 546 if (--(m->mtx_recurse) == 0) 547 atomic_clear_ptr(&m->mtx_lock, MTX_RECURSED); 548 if ((opts & MTX_QUIET) == 0) 549 CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p unrecurse", m); 550 return; 551 } 552 553 mtx_lock_spin(&sched_lock); 554 if ((opts & MTX_QUIET) == 0) 555 CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p contested", m); 556 557 p1 = TAILQ_FIRST(&m->mtx_blocked); 558 MPASS(p->p_magic == P_MAGIC); 559 MPASS(p1->p_magic == P_MAGIC); 560 561 TAILQ_REMOVE(&m->mtx_blocked, p1, p_procq); 562 563 if (TAILQ_EMPTY(&m->mtx_blocked)) { 564 LIST_REMOVE(m, mtx_contested); 565 _release_lock_quick(m); 566 if ((opts & MTX_QUIET) == 0) 567 CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p not held", m); 568 } else 569 atomic_store_rel_ptr(&m->mtx_lock, (void *)MTX_CONTESTED); 570 571 pri = PRI_MAX; 572 LIST_FOREACH(m1, &p->p_contested, mtx_contested) { 573 int cp = TAILQ_FIRST(&m1->mtx_blocked)->p_pri.pri_level; 574 if (cp < pri) 575 pri = cp; 576 } 577 578 if (pri > p->p_pri.pri_native) 579 pri = p->p_pri.pri_native; 580 SET_PRIO(p, pri); 581 582 if ((opts & MTX_QUIET) == 0) 583 CTR2(KTR_LOCK, "_mtx_unlock_sleep: %p contested setrunqueue %p", 584 m, p1); 585 586 p1->p_blocked = NULL; 587 p1->p_stat = SRUN; 588 setrunqueue(p1); 589 590 if ((opts & MTX_NOSWITCH) == 0 && p1->p_pri.pri_level < pri) { 591#ifdef notyet 592 if (p->p_ithd != NULL) { 593 struct ithd *it = p->p_ithd; 594 595 if (it->it_interrupted) { 596 if ((opts & MTX_QUIET) == 0) 597 CTR2(KTR_LOCK, 598 "_mtx_unlock_sleep: %p interrupted %p", 599 it, it->it_interrupted); 600 intr_thd_fixup(it); 601 } 602 } 603#endif 604 setrunqueue(p); 605 if ((opts & MTX_QUIET) == 0) 606 CTR2(KTR_LOCK, 607 "_mtx_unlock_sleep: %p switching out lock=%p", m, 608 (void *)m->mtx_lock); 609 610 mi_switch(); 611 if ((opts & MTX_QUIET) == 0) 612 CTR2(KTR_LOCK, "_mtx_unlock_sleep: %p resuming lock=%p", 613 m, (void *)m->mtx_lock); 614 } 615 616 mtx_unlock_spin(&sched_lock); 617 618 return; 619} 620 621/* 622 * All the unlocking of MTX_SPIN locks is done inline. 623 * See the _rel_spin_lock() macro for the details. 624 */ 625 626/* 627 * The backing function for the INVARIANTS-enabled mtx_assert() 628 */ 629#ifdef INVARIANT_SUPPORT 630void 631_mtx_assert(struct mtx *m, int what, const char *file, int line) 632{ 633 switch (what) { 634 case MA_OWNED: 635 case MA_OWNED | MA_RECURSED: 636 case MA_OWNED | MA_NOTRECURSED: 637 if (!mtx_owned(m)) 638 panic("mutex %s not owned at %s:%d", 639 m->mtx_description, file, line); 640 if (mtx_recursed(m)) { 641 if ((what & MA_NOTRECURSED) != 0) 642 panic("mutex %s recursed at %s:%d", 643 m->mtx_description, file, line); 644 } else if ((what & MA_RECURSED) != 0) { 645 panic("mutex %s unrecursed at %s:%d", 646 m->mtx_description, file, line); 647 } 648 break; 649 case MA_NOTOWNED: 650 if (mtx_owned(m)) 651 panic("mutex %s owned at %s:%d", 652 m->mtx_description, file, line); 653 break; 654 default: 655 panic("unknown mtx_assert at %s:%d", file, line); 656 } 657} 658#endif 659 660/* 661 * The MUTEX_DEBUG-enabled mtx_validate() 662 */ 663#define MV_DESTROY 0 /* validate before destory */ 664#define MV_INIT 1 /* validate before init */ 665 666#ifdef MUTEX_DEBUG 667 668int mtx_validate __P((struct mtx *, int)); 669 670int 671mtx_validate(struct mtx *m, int when) 672{ 673 struct mtx *mp; 674 int i; 675 int retval = 0; 676 677#ifdef WITNESS 678 if (witness_cold) 679 return 0; 680#endif 681 if (m == &all_mtx || cold) 682 return 0; 683 684 mtx_lock(&all_mtx); 685/* 686 * XXX - When kernacc() is fixed on the alpha to handle K0_SEG memory properly 687 * we can re-enable the kernacc() checks. 688 */ 689#ifndef __alpha__ 690 MPASS(kernacc((caddr_t)all_mtx.mtx_next, sizeof(uintptr_t), 691 VM_PROT_READ) == 1); 692#endif 693 MPASS(all_mtx.mtx_next->mtx_prev == &all_mtx); 694 for (i = 0, mp = all_mtx.mtx_next; mp != &all_mtx; mp = mp->mtx_next) { 695#ifndef __alpha__ 696 if (kernacc((caddr_t)mp->mtx_next, sizeof(uintptr_t), 697 VM_PROT_READ) != 1) { 698 panic("mtx_validate: mp=%p mp->mtx_next=%p", 699 mp, mp->mtx_next); 700 } 701#endif 702 i++; 703 if (i > mtx_cur_cnt) { 704 panic("mtx_validate: too many in chain, known=%d\n", 705 mtx_cur_cnt); 706 } 707 } 708 MPASS(i == mtx_cur_cnt); 709 switch (when) { 710 case MV_DESTROY: 711 for (mp = all_mtx.mtx_next; mp != &all_mtx; mp = mp->mtx_next) 712 if (mp == m) 713 break; 714 MPASS(mp == m); 715 break; 716 case MV_INIT: 717 for (mp = all_mtx.mtx_next; mp != &all_mtx; mp = mp->mtx_next) 718 if (mp == m) { 719 /* 720 * Not good. This mutex already exists. 721 */ 722 printf("re-initing existing mutex %s\n", 723 m->mtx_description); 724 MPASS(m->mtx_lock == MTX_UNOWNED); 725 retval = 1; 726 } 727 } 728 mtx_unlock(&all_mtx); 729 return (retval); 730} 731#endif 732 733/* 734 * Mutex initialization routine; initialize lock `m' of type contained in 735 * `opts' with options contained in `opts' and description `description.' 736 * Place on "all_mtx" queue. 737 */ 738void 739mtx_init(struct mtx *m, const char *description, int opts) 740{ 741 742 if ((opts & MTX_QUIET) == 0) 743 CTR2(KTR_LOCK, "mtx_init %p (%s)", m, description); 744 745#ifdef MUTEX_DEBUG 746 /* Diagnostic and error correction */ 747 if (mtx_validate(m, MV_INIT)) 748 return; 749#endif 750 751 bzero((void *)m, sizeof *m); 752 TAILQ_INIT(&m->mtx_blocked); 753 754#ifdef WITNESS 755 if (!witness_cold) { 756 m->mtx_debug = malloc(sizeof(struct mtx_debug), 757 M_WITNESS, M_NOWAIT | M_ZERO); 758 MPASS(m->mtx_debug != NULL); 759 } 760#endif 761 762 m->mtx_description = description; 763 m->mtx_flags = opts; 764 m->mtx_lock = MTX_UNOWNED; 765 766 /* Put on all mutex queue */ 767 mtx_lock(&all_mtx); 768 m->mtx_next = &all_mtx; 769 m->mtx_prev = all_mtx.mtx_prev; 770 m->mtx_prev->mtx_next = m; 771 all_mtx.mtx_prev = m; 772 if (++mtx_cur_cnt > mtx_max_cnt) 773 mtx_max_cnt = mtx_cur_cnt; 774 mtx_unlock(&all_mtx); 775 776#ifdef WITNESS 777 if (!witness_cold) 778 witness_init(m, opts); 779#endif 780} 781 782/* 783 * Remove lock `m' from all_mtx queue. 784 */ 785void 786mtx_destroy(struct mtx *m) 787{ 788 789#ifdef WITNESS 790 KASSERT(!witness_cold, ("%s: Cannot destroy while still cold\n", 791 __FUNCTION__)); 792#endif 793 794 CTR2(KTR_LOCK, "mtx_destroy %p (%s)", m, m->mtx_description); 795 796#ifdef MUTEX_DEBUG 797 if (m->mtx_next == NULL) 798 panic("mtx_destroy: %p (%s) already destroyed", 799 m, m->mtx_description); 800 801 if (!mtx_owned(m)) { 802 MPASS(m->mtx_lock == MTX_UNOWNED); 803 } else { 804 MPASS((m->mtx_lock & (MTX_RECURSED|MTX_CONTESTED)) == 0); 805 } 806 807 /* diagnostic */ 808 mtx_validate(m, MV_DESTROY); 809#endif 810 811#ifdef WITNESS 812 if (m->mtx_witness) 813 witness_destroy(m); 814#endif /* WITNESS */ 815 816 /* Remove from the all mutex queue */ 817 mtx_lock(&all_mtx); 818 m->mtx_next->mtx_prev = m->mtx_prev; 819 m->mtx_prev->mtx_next = m->mtx_next; 820 821#ifdef MUTEX_DEBUG 822 m->mtx_next = m->mtx_prev = NULL; 823#endif 824 825#ifdef WITNESS 826 free(m->mtx_debug, M_WITNESS); 827 m->mtx_debug = NULL; 828#endif 829 830 mtx_cur_cnt--; 831 mtx_unlock(&all_mtx); 832} 833 834 835/* 836 * The WITNESS-enabled diagnostic code. 837 */ 838#ifdef WITNESS 839static void 840witness_fixup(void *dummy __unused) 841{ 842 struct mtx *mp; 843 844 /* 845 * We have to release Giant before initializing its witness 846 * structure so that WITNESS doesn't get confused. 847 */ 848 mtx_unlock(&Giant); 849 mtx_assert(&Giant, MA_NOTOWNED); 850 851 mtx_lock(&all_mtx); 852 853 /* Iterate through all mutexes and finish up mutex initialization. */ 854 for (mp = all_mtx.mtx_next; mp != &all_mtx; mp = mp->mtx_next) { 855 856 mp->mtx_debug = malloc(sizeof(struct mtx_debug), 857 M_WITNESS, M_NOWAIT | M_ZERO); 858 MPASS(mp->mtx_debug != NULL); 859 860 witness_init(mp, mp->mtx_flags); 861 } 862 mtx_unlock(&all_mtx); 863 864 /* Mark the witness code as being ready for use. */ 865 atomic_store_rel_int(&witness_cold, 0); 866 867 mtx_lock(&Giant); 868} 869SYSINIT(wtnsfxup, SI_SUB_MUTEX, SI_ORDER_FIRST, witness_fixup, NULL) 870 871#define WITNESS_COUNT 200 872#define WITNESS_NCHILDREN 2 873 874int witness_watch = 1; 875 876struct witness { 877 struct witness *w_next; 878 const char *w_description; 879 const char *w_file; 880 int w_line; 881 struct witness *w_morechildren; 882 u_char w_childcnt; 883 u_char w_Giant_squawked:1; 884 u_char w_other_squawked:1; 885 u_char w_same_squawked:1; 886 u_char w_spin:1; /* MTX_SPIN type mutex. */ 887 u_int w_level; 888 struct witness *w_children[WITNESS_NCHILDREN]; 889}; 890 891struct witness_blessed { 892 char *b_lock1; 893 char *b_lock2; 894}; 895 896#ifdef DDB 897/* 898 * When DDB is enabled and witness_ddb is set to 1, it will cause the system to 899 * drop into kdebug() when: 900 * - a lock heirarchy violation occurs 901 * - locks are held when going to sleep. 902 */ 903int witness_ddb; 904#ifdef WITNESS_DDB 905TUNABLE_INT_DECL("debug.witness_ddb", 1, witness_ddb); 906#else 907TUNABLE_INT_DECL("debug.witness_ddb", 0, witness_ddb); 908#endif 909SYSCTL_INT(_debug, OID_AUTO, witness_ddb, CTLFLAG_RW, &witness_ddb, 0, ""); 910#endif /* DDB */ 911 912int witness_skipspin; 913#ifdef WITNESS_SKIPSPIN 914TUNABLE_INT_DECL("debug.witness_skipspin", 1, witness_skipspin); 915#else 916TUNABLE_INT_DECL("debug.witness_skipspin", 0, witness_skipspin); 917#endif 918SYSCTL_INT(_debug, OID_AUTO, witness_skipspin, CTLFLAG_RD, &witness_skipspin, 0, 919 ""); 920 921/* 922 * Witness-enabled globals 923 */ 924static struct mtx w_mtx; 925static struct witness *w_free; 926static struct witness *w_all; 927static int w_inited; 928static int witness_dead; /* fatal error, probably no memory */ 929 930static struct witness w_data[WITNESS_COUNT]; 931 932/* 933 * Internal witness routine prototypes 934 */ 935static struct witness *enroll(const char *description, int flag); 936static int itismychild(struct witness *parent, struct witness *child); 937static void removechild(struct witness *parent, struct witness *child); 938static int isitmychild(struct witness *parent, struct witness *child); 939static int isitmydescendant(struct witness *parent, struct witness *child); 940static int dup_ok(struct witness *); 941static int blessed(struct witness *, struct witness *); 942static void 943 witness_displaydescendants(void(*)(const char *fmt, ...), struct witness *); 944static void witness_leveldescendents(struct witness *parent, int level); 945static void witness_levelall(void); 946static struct witness * witness_get(void); 947static void witness_free(struct witness *m); 948 949static char *ignore_list[] = { 950 "witness lock", 951 NULL 952}; 953 954static char *spin_order_list[] = { 955#if defined(__i386__) && defined (SMP) 956 "com", 957#endif 958 "sio", 959#ifdef __i386__ 960 "cy", 961#endif 962 "ng_node", 963 "ng_worklist", 964 "ithread table lock", 965 "ithread list lock", 966 "sched lock", 967#ifdef __i386__ 968 "clk", 969#endif 970 "callout", 971 /* 972 * leaf locks 973 */ 974#ifdef SMP 975#ifdef __i386__ 976 "ap boot", 977 "imen", 978#endif 979 "smp rendezvous", 980#endif 981 NULL 982}; 983 984static char *order_list[] = { 985 "Giant", "proctree", "allproc", "process lock", "uidinfo hash", 986 "uidinfo struct", NULL, 987 NULL 988}; 989 990static char *dup_list[] = { 991 "process lock", 992 NULL 993}; 994 995static char *sleep_list[] = { 996 "Giant", 997 NULL 998}; 999 1000/* 1001 * Pairs of locks which have been blessed 1002 * Don't complain about order problems with blessed locks 1003 */ 1004static struct witness_blessed blessed_list[] = { 1005}; 1006static int blessed_count = 1007 sizeof(blessed_list) / sizeof(struct witness_blessed); 1008 1009static void 1010witness_init(struct mtx *m, int flag) 1011{ 1012 m->mtx_witness = enroll(m->mtx_description, flag); 1013} 1014 1015static void 1016witness_destroy(struct mtx *m) 1017{ 1018 struct mtx *m1; 1019 struct proc *p; 1020 p = curproc; 1021 LIST_FOREACH(m1, &p->p_heldmtx, mtx_held) { 1022 if (m1 == m) { 1023 LIST_REMOVE(m, mtx_held); 1024 break; 1025 } 1026 } 1027 return; 1028 1029} 1030 1031static void 1032witness_display(void(*prnt)(const char *fmt, ...)) 1033{ 1034 struct witness *w, *w1; 1035 int level, found; 1036 1037 KASSERT(!witness_cold, ("%s: witness_cold\n", __FUNCTION__)); 1038 witness_levelall(); 1039 1040 /* 1041 * First, handle sleep mutexes which have been acquired at least 1042 * once. 1043 */ 1044 prnt("Sleep mutexes:\n"); 1045 for (w = w_all; w; w = w->w_next) { 1046 if (w->w_file == NULL || w->w_spin) 1047 continue; 1048 for (w1 = w_all; w1; w1 = w1->w_next) { 1049 if (isitmychild(w1, w)) 1050 break; 1051 } 1052 if (w1 != NULL) 1053 continue; 1054 /* 1055 * This lock has no anscestors, display its descendants. 1056 */ 1057 witness_displaydescendants(prnt, w); 1058 } 1059 1060 /* 1061 * Now do spin mutexes which have been acquired at least once. 1062 */ 1063 prnt("\nSpin mutexes:\n"); 1064 level = 0; 1065 while (level < sizeof(spin_order_list) / sizeof(char *)) { 1066 found = 0; 1067 for (w = w_all; w; w = w->w_next) { 1068 if (w->w_file == NULL || !w->w_spin) 1069 continue; 1070 if (w->w_level == 1 << level) { 1071 witness_displaydescendants(prnt, w); 1072 level++; 1073 found = 1; 1074 } 1075 } 1076 if (found == 0) 1077 level++; 1078 } 1079 1080 /* 1081 * Finally, any mutexes which have not been acquired yet. 1082 */ 1083 prnt("\nMutexes which were never acquired:\n"); 1084 for (w = w_all; w; w = w->w_next) { 1085 if (w->w_file != NULL) 1086 continue; 1087 prnt("%s\n", w->w_description); 1088 } 1089} 1090 1091void 1092witness_enter(struct mtx *m, int flags, const char *file, int line) 1093{ 1094 struct witness *w, *w1; 1095 struct mtx *m1; 1096 struct proc *p; 1097 int i; 1098#ifdef DDB 1099 int go_into_ddb = 0; 1100#endif /* DDB */ 1101 1102 if (witness_cold || m->mtx_witness == NULL || panicstr) 1103 return; 1104 w = m->mtx_witness; 1105 p = curproc; 1106 1107 if (flags & MTX_SPIN) { 1108 if ((m->mtx_flags & MTX_SPIN) == 0) 1109 panic("mutex_enter: MTX_SPIN on MTX_DEF mutex %s @" 1110 " %s:%d", m->mtx_description, file, line); 1111 if (mtx_recursed(m)) { 1112 if ((m->mtx_flags & MTX_RECURSE) == 0) 1113 panic("mutex_enter: recursion on non-recursive" 1114 " mutex %s @ %s:%d", m->mtx_description, 1115 file, line); 1116 return; 1117 } 1118 mtx_lock_spin_flags(&w_mtx, MTX_QUIET); 1119 i = PCPU_GET(witness_spin_check); 1120 if (i != 0 && w->w_level < i) { 1121 mtx_unlock_spin_flags(&w_mtx, MTX_QUIET); 1122 panic("mutex_enter(%s:%x, MTX_SPIN) out of order @" 1123 " %s:%d already holding %s:%x", 1124 m->mtx_description, w->w_level, file, line, 1125 spin_order_list[ffs(i)-1], i); 1126 } 1127 PCPU_SET(witness_spin_check, i | w->w_level); 1128 mtx_unlock_spin_flags(&w_mtx, MTX_QUIET); 1129 p->p_spinlocks++; 1130 MPASS(p->p_spinlocks > 0); 1131 w->w_file = file; 1132 w->w_line = line; 1133 m->mtx_line = line; 1134 m->mtx_file = file; 1135 return; 1136 } 1137 if ((m->mtx_flags & MTX_SPIN) != 0) 1138 panic("mutex_enter: MTX_DEF on MTX_SPIN mutex %s @ %s:%d", 1139 m->mtx_description, file, line); 1140 1141 if (mtx_recursed(m)) { 1142 if ((m->mtx_flags & MTX_RECURSE) == 0) 1143 panic("mutex_enter: recursion on non-recursive" 1144 " mutex %s @ %s:%d", m->mtx_description, 1145 file, line); 1146 return; 1147 } 1148 if (witness_dead) 1149 goto out; 1150 if (cold) 1151 goto out; 1152 1153 if (p->p_spinlocks != 0) 1154 panic("blockable mtx_lock() of %s when not legal @ %s:%d", 1155 m->mtx_description, file, line); 1156 /* 1157 * Is this the first mutex acquired 1158 */ 1159 if ((m1 = LIST_FIRST(&p->p_heldmtx)) == NULL) 1160 goto out; 1161 1162 if ((w1 = m1->mtx_witness) == w) { 1163 if (w->w_same_squawked || dup_ok(w)) 1164 goto out; 1165 w->w_same_squawked = 1; 1166 printf("acquring duplicate lock of same type: \"%s\"\n", 1167 m->mtx_description); 1168 printf(" 1st @ %s:%d\n", w->w_file, w->w_line); 1169 printf(" 2nd @ %s:%d\n", file, line); 1170#ifdef DDB 1171 go_into_ddb = 1; 1172#endif /* DDB */ 1173 goto out; 1174 } 1175 MPASS(!mtx_owned(&w_mtx)); 1176 mtx_lock_spin_flags(&w_mtx, MTX_QUIET); 1177 /* 1178 * If we have a known higher number just say ok 1179 */ 1180 if (witness_watch > 1 && w->w_level > w1->w_level) { 1181 mtx_unlock_spin_flags(&w_mtx, MTX_QUIET); 1182 goto out; 1183 } 1184 if (isitmydescendant(m1->mtx_witness, w)) { 1185 mtx_unlock_spin_flags(&w_mtx, MTX_QUIET); 1186 goto out; 1187 } 1188 for (i = 0; m1 != NULL; m1 = LIST_NEXT(m1, mtx_held), i++) { 1189 1190 MPASS(i < 200); 1191 w1 = m1->mtx_witness; 1192 if (isitmydescendant(w, w1)) { 1193 mtx_unlock_spin_flags(&w_mtx, MTX_QUIET); 1194 if (blessed(w, w1)) 1195 goto out; 1196 if (m1 == &Giant) { 1197 if (w1->w_Giant_squawked) 1198 goto out; 1199 else 1200 w1->w_Giant_squawked = 1; 1201 } else { 1202 if (w1->w_other_squawked) 1203 goto out; 1204 else 1205 w1->w_other_squawked = 1; 1206 } 1207 printf("lock order reversal\n"); 1208 printf(" 1st %s last acquired @ %s:%d\n", 1209 w->w_description, w->w_file, w->w_line); 1210 printf(" 2nd %p %s @ %s:%d\n", 1211 m1, w1->w_description, w1->w_file, w1->w_line); 1212 printf(" 3rd %p %s @ %s:%d\n", 1213 m, w->w_description, file, line); 1214#ifdef DDB 1215 go_into_ddb = 1; 1216#endif /* DDB */ 1217 goto out; 1218 } 1219 } 1220 m1 = LIST_FIRST(&p->p_heldmtx); 1221 if (!itismychild(m1->mtx_witness, w)) 1222 mtx_unlock_spin_flags(&w_mtx, MTX_QUIET); 1223 1224out: 1225#ifdef DDB 1226 if (witness_ddb && go_into_ddb) 1227 Debugger("witness_enter"); 1228#endif /* DDB */ 1229 w->w_file = file; 1230 w->w_line = line; 1231 m->mtx_line = line; 1232 m->mtx_file = file; 1233 1234 /* 1235 * If this pays off it likely means that a mutex being witnessed 1236 * is acquired in hardclock. Put it in the ignore list. It is 1237 * likely not the mutex this assert fails on. 1238 */ 1239 MPASS(m->mtx_held.le_prev == NULL); 1240 LIST_INSERT_HEAD(&p->p_heldmtx, (struct mtx*)m, mtx_held); 1241} 1242 1243void 1244witness_try_enter(struct mtx *m, int flags, const char *file, int line) 1245{ 1246 struct proc *p; 1247 struct witness *w = m->mtx_witness; 1248 1249 if (witness_cold) 1250 return; 1251 if (panicstr) 1252 return; 1253 if (flags & MTX_SPIN) { 1254 if ((m->mtx_flags & MTX_SPIN) == 0) 1255 panic("mutex_try_enter: " 1256 "MTX_SPIN on MTX_DEF mutex %s @ %s:%d", 1257 m->mtx_description, file, line); 1258 if (mtx_recursed(m)) { 1259 if ((m->mtx_flags & MTX_RECURSE) == 0) 1260 panic("mutex_try_enter: recursion on" 1261 " non-recursive mutex %s @ %s:%d", 1262 m->mtx_description, file, line); 1263 return; 1264 } 1265 mtx_lock_spin_flags(&w_mtx, MTX_QUIET); 1266 PCPU_SET(witness_spin_check, 1267 PCPU_GET(witness_spin_check) | w->w_level); 1268 mtx_unlock_spin_flags(&w_mtx, MTX_QUIET); 1269 w->w_file = file; 1270 w->w_line = line; 1271 m->mtx_line = line; 1272 m->mtx_file = file; 1273 return; 1274 } 1275 1276 if ((m->mtx_flags & MTX_SPIN) != 0) 1277 panic("mutex_try_enter: MTX_DEF on MTX_SPIN mutex %s @ %s:%d", 1278 m->mtx_description, file, line); 1279 1280 if (mtx_recursed(m)) { 1281 if ((m->mtx_flags & MTX_RECURSE) == 0) 1282 panic("mutex_try_enter: recursion on non-recursive" 1283 " mutex %s @ %s:%d", m->mtx_description, file, 1284 line); 1285 return; 1286 } 1287 w->w_file = file; 1288 w->w_line = line; 1289 m->mtx_line = line; 1290 m->mtx_file = file; 1291 p = curproc; 1292 MPASS(m->mtx_held.le_prev == NULL); 1293 LIST_INSERT_HEAD(&p->p_heldmtx, (struct mtx*)m, mtx_held); 1294} 1295 1296void 1297witness_exit(struct mtx *m, int flags, const char *file, int line) 1298{ 1299 struct witness *w; 1300 struct proc *p; 1301 1302 if (witness_cold || m->mtx_witness == NULL || panicstr) 1303 return; 1304 w = m->mtx_witness; 1305 p = curproc; 1306 1307 if (flags & MTX_SPIN) { 1308 if ((m->mtx_flags & MTX_SPIN) == 0) 1309 panic("mutex_exit: MTX_SPIN on MTX_DEF mutex %s @" 1310 " %s:%d", m->mtx_description, file, line); 1311 if (mtx_recursed(m)) { 1312 if ((m->mtx_flags & MTX_RECURSE) == 0) 1313 panic("mutex_exit: recursion on non-recursive" 1314 " mutex %s @ %s:%d", m->mtx_description, 1315 file, line); 1316 return; 1317 } 1318 mtx_lock_spin_flags(&w_mtx, MTX_QUIET); 1319 PCPU_SET(witness_spin_check, 1320 PCPU_GET(witness_spin_check) & ~w->w_level); 1321 mtx_unlock_spin_flags(&w_mtx, MTX_QUIET); 1322 MPASS(p->p_spinlocks > 0); 1323 p->p_spinlocks--; 1324 return; 1325 } 1326 if ((m->mtx_flags & MTX_SPIN) != 0) 1327 panic("mutex_exit: MTX_DEF on MTX_SPIN mutex %s @ %s:%d", 1328 m->mtx_description, file, line); 1329 1330 if (mtx_recursed(m)) { 1331 if ((m->mtx_flags & MTX_RECURSE) == 0) 1332 panic("mutex_exit: recursion on non-recursive" 1333 " mutex %s @ %s:%d", m->mtx_description, 1334 file, line); 1335 return; 1336 } 1337 1338 if ((flags & MTX_NOSWITCH) == 0 && p->p_spinlocks != 0 && !cold) 1339 panic("switchable mtx_unlock() of %s when not legal @ %s:%d", 1340 m->mtx_description, file, line); 1341 LIST_REMOVE(m, mtx_held); 1342 m->mtx_held.le_prev = NULL; 1343} 1344 1345int 1346witness_sleep(int check_only, struct mtx *mtx, const char *file, int line) 1347{ 1348 struct mtx *m; 1349 struct proc *p; 1350 char **sleep; 1351 int n = 0; 1352 1353 KASSERT(!witness_cold, ("%s: witness_cold\n", __FUNCTION__)); 1354 p = curproc; 1355 LIST_FOREACH(m, &p->p_heldmtx, mtx_held) { 1356 if (m == mtx) 1357 continue; 1358 for (sleep = sleep_list; *sleep!= NULL; sleep++) 1359 if (strcmp(m->mtx_description, *sleep) == 0) 1360 goto next; 1361 if (n == 0) 1362 printf("Whee!\n"); 1363 printf("%s:%d: %s with \"%s\" locked from %s:%d\n", 1364 file, line, check_only ? "could sleep" : "sleeping", 1365 m->mtx_description, 1366 m->mtx_witness->w_file, m->mtx_witness->w_line); 1367 n++; 1368 next: 1369 } 1370#ifdef DDB 1371 if (witness_ddb && n) 1372 Debugger("witness_sleep"); 1373#endif /* DDB */ 1374 return (n); 1375} 1376 1377static struct witness * 1378enroll(const char *description, int flag) 1379{ 1380 int i; 1381 struct witness *w, *w1; 1382 char **ignore; 1383 char **order; 1384 1385 if (!witness_watch) 1386 return (NULL); 1387 for (ignore = ignore_list; *ignore != NULL; ignore++) 1388 if (strcmp(description, *ignore) == 0) 1389 return (NULL); 1390 1391 if (w_inited == 0) { 1392 mtx_init(&w_mtx, "witness lock", MTX_SPIN); 1393 for (i = 0; i < WITNESS_COUNT; i++) { 1394 w = &w_data[i]; 1395 witness_free(w); 1396 } 1397 w_inited = 1; 1398 for (order = order_list; *order != NULL; order++) { 1399 w = enroll(*order, MTX_DEF); 1400 w->w_file = "order list"; 1401 for (order++; *order != NULL; order++) { 1402 w1 = enroll(*order, MTX_DEF); 1403 w1->w_file = "order list"; 1404 itismychild(w, w1); 1405 w = w1; 1406 } 1407 } 1408 } 1409 if ((flag & MTX_SPIN) && witness_skipspin) 1410 return (NULL); 1411 mtx_lock_spin_flags(&w_mtx, MTX_QUIET); 1412 for (w = w_all; w; w = w->w_next) { 1413 if (strcmp(description, w->w_description) == 0) { 1414 mtx_unlock_spin_flags(&w_mtx, MTX_QUIET); 1415 return (w); 1416 } 1417 } 1418 if ((w = witness_get()) == NULL) 1419 return (NULL); 1420 w->w_next = w_all; 1421 w_all = w; 1422 w->w_description = description; 1423 mtx_unlock_spin_flags(&w_mtx, MTX_QUIET); 1424 if (flag & MTX_SPIN) { 1425 w->w_spin = 1; 1426 1427 i = 1; 1428 for (order = spin_order_list; *order != NULL; order++) { 1429 if (strcmp(description, *order) == 0) 1430 break; 1431 i <<= 1; 1432 } 1433 if (*order == NULL) 1434 panic("spin lock %s not in order list", description); 1435 w->w_level = i; 1436 } 1437 1438 return (w); 1439} 1440 1441static int 1442itismychild(struct witness *parent, struct witness *child) 1443{ 1444 static int recursed; 1445 1446 /* 1447 * Insert "child" after "parent" 1448 */ 1449 while (parent->w_morechildren) 1450 parent = parent->w_morechildren; 1451 1452 if (parent->w_childcnt == WITNESS_NCHILDREN) { 1453 if ((parent->w_morechildren = witness_get()) == NULL) 1454 return (1); 1455 parent = parent->w_morechildren; 1456 } 1457 MPASS(child != NULL); 1458 parent->w_children[parent->w_childcnt++] = child; 1459 /* 1460 * now prune whole tree 1461 */ 1462 if (recursed) 1463 return (0); 1464 recursed = 1; 1465 for (child = w_all; child != NULL; child = child->w_next) { 1466 for (parent = w_all; parent != NULL; 1467 parent = parent->w_next) { 1468 if (!isitmychild(parent, child)) 1469 continue; 1470 removechild(parent, child); 1471 if (isitmydescendant(parent, child)) 1472 continue; 1473 itismychild(parent, child); 1474 } 1475 } 1476 recursed = 0; 1477 witness_levelall(); 1478 return (0); 1479} 1480 1481static void 1482removechild(struct witness *parent, struct witness *child) 1483{ 1484 struct witness *w, *w1; 1485 int i; 1486 1487 for (w = parent; w != NULL; w = w->w_morechildren) 1488 for (i = 0; i < w->w_childcnt; i++) 1489 if (w->w_children[i] == child) 1490 goto found; 1491 return; 1492found: 1493 for (w1 = w; w1->w_morechildren != NULL; w1 = w1->w_morechildren) 1494 continue; 1495 w->w_children[i] = w1->w_children[--w1->w_childcnt]; 1496 MPASS(w->w_children[i] != NULL); 1497 1498 if (w1->w_childcnt != 0) 1499 return; 1500 1501 if (w1 == parent) 1502 return; 1503 for (w = parent; w->w_morechildren != w1; w = w->w_morechildren) 1504 continue; 1505 w->w_morechildren = 0; 1506 witness_free(w1); 1507} 1508 1509static int 1510isitmychild(struct witness *parent, struct witness *child) 1511{ 1512 struct witness *w; 1513 int i; 1514 1515 for (w = parent; w != NULL; w = w->w_morechildren) { 1516 for (i = 0; i < w->w_childcnt; i++) { 1517 if (w->w_children[i] == child) 1518 return (1); 1519 } 1520 } 1521 return (0); 1522} 1523 1524static int 1525isitmydescendant(struct witness *parent, struct witness *child) 1526{ 1527 struct witness *w; 1528 int i; 1529 int j; 1530 1531 for (j = 0, w = parent; w != NULL; w = w->w_morechildren, j++) { 1532 MPASS(j < 1000); 1533 for (i = 0; i < w->w_childcnt; i++) { 1534 if (w->w_children[i] == child) 1535 return (1); 1536 } 1537 for (i = 0; i < w->w_childcnt; i++) { 1538 if (isitmydescendant(w->w_children[i], child)) 1539 return (1); 1540 } 1541 } 1542 return (0); 1543} 1544 1545void 1546witness_levelall (void) 1547{ 1548 struct witness *w, *w1; 1549 1550 for (w = w_all; w; w = w->w_next) 1551 if (!(w->w_spin)) 1552 w->w_level = 0; 1553 for (w = w_all; w; w = w->w_next) { 1554 if (w->w_spin) 1555 continue; 1556 for (w1 = w_all; w1; w1 = w1->w_next) { 1557 if (isitmychild(w1, w)) 1558 break; 1559 } 1560 if (w1 != NULL) 1561 continue; 1562 witness_leveldescendents(w, 0); 1563 } 1564} 1565 1566static void 1567witness_leveldescendents(struct witness *parent, int level) 1568{ 1569 int i; 1570 struct witness *w; 1571 1572 if (parent->w_level < level) 1573 parent->w_level = level; 1574 level++; 1575 for (w = parent; w != NULL; w = w->w_morechildren) 1576 for (i = 0; i < w->w_childcnt; i++) 1577 witness_leveldescendents(w->w_children[i], level); 1578} 1579 1580static void 1581witness_displaydescendants(void(*prnt)(const char *fmt, ...), 1582 struct witness *parent) 1583{ 1584 struct witness *w; 1585 int i; 1586 int level; 1587 1588 level = parent->w_spin ? ffs(parent->w_level) : parent->w_level; 1589 1590 prnt("%d", level); 1591 if (level < 10) 1592 prnt(" "); 1593 for (i = 0; i < level; i++) 1594 prnt(" "); 1595 prnt("%s", parent->w_description); 1596 if (parent->w_file != NULL) 1597 prnt(" -- last acquired @ %s:%d\n", parent->w_file, 1598 parent->w_line); 1599 1600 for (w = parent; w != NULL; w = w->w_morechildren) 1601 for (i = 0; i < w->w_childcnt; i++) 1602 witness_displaydescendants(prnt, w->w_children[i]); 1603 } 1604 1605static int 1606dup_ok(struct witness *w) 1607{ 1608 char **dup; 1609 1610 for (dup = dup_list; *dup!= NULL; dup++) 1611 if (strcmp(w->w_description, *dup) == 0) 1612 return (1); 1613 return (0); 1614} 1615 1616static int 1617blessed(struct witness *w1, struct witness *w2) 1618{ 1619 int i; 1620 struct witness_blessed *b; 1621 1622 for (i = 0; i < blessed_count; i++) { 1623 b = &blessed_list[i]; 1624 if (strcmp(w1->w_description, b->b_lock1) == 0) { 1625 if (strcmp(w2->w_description, b->b_lock2) == 0) 1626 return (1); 1627 continue; 1628 } 1629 if (strcmp(w1->w_description, b->b_lock2) == 0) 1630 if (strcmp(w2->w_description, b->b_lock1) == 0) 1631 return (1); 1632 } 1633 return (0); 1634} 1635 1636static struct witness * 1637witness_get() 1638{ 1639 struct witness *w; 1640 1641 if ((w = w_free) == NULL) { 1642 witness_dead = 1; 1643 mtx_unlock_spin_flags(&w_mtx, MTX_QUIET); 1644 printf("witness exhausted\n"); 1645 return (NULL); 1646 } 1647 w_free = w->w_next; 1648 bzero(w, sizeof(*w)); 1649 return (w); 1650} 1651 1652static void 1653witness_free(struct witness *w) 1654{ 1655 w->w_next = w_free; 1656 w_free = w; 1657} 1658 1659int 1660witness_list(struct proc *p) 1661{ 1662 struct mtx *m; 1663 int nheld; 1664 1665 KASSERT(!witness_cold, ("%s: witness_cold\n", __FUNCTION__)); 1666 nheld = 0; 1667 LIST_FOREACH(m, &p->p_heldmtx, mtx_held) { 1668 printf("\t\"%s\" (%p) locked at %s:%d\n", 1669 m->mtx_description, m, 1670 m->mtx_witness->w_file, m->mtx_witness->w_line); 1671 nheld++; 1672 } 1673 1674 return (nheld); 1675} 1676 1677#ifdef DDB 1678 1679DB_SHOW_COMMAND(mutexes, db_witness_list) 1680{ 1681 1682 witness_list(curproc); 1683} 1684 1685DB_SHOW_COMMAND(witness, db_witness_display) 1686{ 1687 1688 witness_display(db_printf); 1689} 1690#endif 1691 1692void 1693witness_save(struct mtx *m, const char **filep, int *linep) 1694{ 1695 1696 KASSERT(!witness_cold, ("%s: witness_cold\n", __FUNCTION__)); 1697 if (m->mtx_witness == NULL) 1698 return; 1699 1700 *filep = m->mtx_witness->w_file; 1701 *linep = m->mtx_witness->w_line; 1702} 1703 1704void 1705witness_restore(struct mtx *m, const char *file, int line) 1706{ 1707 1708 KASSERT(!witness_cold, ("%s: witness_cold\n", __FUNCTION__)); 1709 if (m->mtx_witness == NULL) 1710 return; 1711 1712 m->mtx_witness->w_file = file; 1713 m->mtx_witness->w_line = line; 1714} 1715 1716#endif /* WITNESS */ 1717