kern_mutex.c revision 74016
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/kern_mutex.c 74016 2001-03-09 07:24:17Z 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 * The important part of mtx_trylock{,_flags}() 289 * Tries to acquire lock `m.' We do NOT handle recursion here; we assume that 290 * if we're called, it's because we know we don't already own this lock. 291 */ 292int 293_mtx_trylock(struct mtx *m, int opts, const char *file, int line) 294{ 295 int rval; 296 297 MPASS(curproc != NULL); 298 299 /* 300 * _mtx_trylock does not accept MTX_NOSWITCH option. 301 */ 302 KASSERT((opts & MTX_NOSWITCH) == 0, 303 ("mtx_trylock() called with invalid option flag(s) %d", opts)); 304 305 rval = _obtain_lock(m, curproc); 306 307#ifdef WITNESS 308 if (rval && m->mtx_witness != NULL) { 309 /* 310 * We do not handle recursion in _mtx_trylock; see the 311 * note at the top of the routine. 312 */ 313 KASSERT(!mtx_recursed(m), 314 ("mtx_trylock() called on a recursed mutex")); 315 witness_try_enter(m, (opts | m->mtx_flags), file, line); 316 } 317#endif /* WITNESS */ 318 319 if ((opts & MTX_QUIET) == 0) 320 CTR5(KTR_LOCK, "TRY_LOCK %s [%p] result=%d at %s:%d", 321 m->mtx_description, m, rval, file, line); 322 323 return rval; 324} 325 326/* 327 * _mtx_lock_sleep: the tougher part of acquiring an MTX_DEF lock. 328 * 329 * We call this if the lock is either contested (i.e. we need to go to 330 * sleep waiting for it), or if we need to recurse on it. 331 */ 332void 333_mtx_lock_sleep(struct mtx *m, int opts, const char *file, int line) 334{ 335 struct proc *p = curproc; 336 337 if ((m->mtx_lock & MTX_FLAGMASK) == (uintptr_t)p) { 338 m->mtx_recurse++; 339 atomic_set_ptr(&m->mtx_lock, MTX_RECURSED); 340 if ((opts & MTX_QUIET) == 0) 341 CTR1(KTR_LOCK, "_mtx_lock_sleep: %p recursing", m); 342 return; 343 } 344 345 if ((opts & MTX_QUIET) == 0) 346 CTR4(KTR_LOCK, 347 "_mtx_lock_sleep: %s contested (lock=%p) at %s:%d", 348 m->mtx_description, (void *)m->mtx_lock, file, line); 349 350 while (!_obtain_lock(m, p)) { 351 uintptr_t v; 352 struct proc *p1; 353 354 mtx_lock_spin(&sched_lock); 355 /* 356 * Check if the lock has been released while spinning for 357 * the sched_lock. 358 */ 359 if ((v = m->mtx_lock) == MTX_UNOWNED) { 360 mtx_unlock_spin(&sched_lock); 361 continue; 362 } 363 364 /* 365 * The mutex was marked contested on release. This means that 366 * there are processes blocked on it. 367 */ 368 if (v == MTX_CONTESTED) { 369 p1 = TAILQ_FIRST(&m->mtx_blocked); 370 MPASS(p1 != NULL); 371 m->mtx_lock = (uintptr_t)p | MTX_CONTESTED; 372 373 if (p1->p_pri.pri_level < p->p_pri.pri_level) 374 SET_PRIO(p, p1->p_pri.pri_level); 375 mtx_unlock_spin(&sched_lock); 376 return; 377 } 378 379 /* 380 * If the mutex isn't already contested and a failure occurs 381 * setting the contested bit, the mutex was either released 382 * or the state of the MTX_RECURSED bit changed. 383 */ 384 if ((v & MTX_CONTESTED) == 0 && 385 !atomic_cmpset_ptr(&m->mtx_lock, (void *)v, 386 (void *)(v | MTX_CONTESTED))) { 387 mtx_unlock_spin(&sched_lock); 388 continue; 389 } 390 391 /* 392 * We deffinately must sleep for this lock. 393 */ 394 mtx_assert(m, MA_NOTOWNED); 395 396#ifdef notyet 397 /* 398 * If we're borrowing an interrupted thread's VM context, we 399 * must clean up before going to sleep. 400 */ 401 if (p->p_ithd != NULL) { 402 struct ithd *it = p->p_ithd; 403 404 if (it->it_interrupted) { 405 if ((opts & MTX_QUIET) == 0) 406 CTR2(KTR_LOCK, 407 "_mtx_lock_sleep: %p interrupted %p", 408 it, it->it_interrupted); 409 intr_thd_fixup(it); 410 } 411 } 412#endif 413 414 /* 415 * Put us on the list of threads blocked on this mutex. 416 */ 417 if (TAILQ_EMPTY(&m->mtx_blocked)) { 418 p1 = (struct proc *)(m->mtx_lock & MTX_FLAGMASK); 419 LIST_INSERT_HEAD(&p1->p_contested, m, mtx_contested); 420 TAILQ_INSERT_TAIL(&m->mtx_blocked, p, p_procq); 421 } else { 422 TAILQ_FOREACH(p1, &m->mtx_blocked, p_procq) 423 if (p1->p_pri.pri_level > p->p_pri.pri_level) 424 break; 425 if (p1) 426 TAILQ_INSERT_BEFORE(p1, p, p_procq); 427 else 428 TAILQ_INSERT_TAIL(&m->mtx_blocked, p, p_procq); 429 } 430 431 /* 432 * Save who we're blocked on. 433 */ 434 p->p_blocked = m; 435 p->p_mtxname = m->mtx_description; 436 p->p_stat = SMTX; 437 propagate_priority(p); 438 439 if ((opts & MTX_QUIET) == 0) 440 CTR3(KTR_LOCK, 441 "_mtx_lock_sleep: p %p blocked on [%p] %s", p, m, 442 m->mtx_description); 443 444 mi_switch(); 445 446 if ((opts & MTX_QUIET) == 0) 447 CTR3(KTR_LOCK, 448 "_mtx_lock_sleep: p %p free from blocked on [%p] %s", 449 p, m, m->mtx_description); 450 451 mtx_unlock_spin(&sched_lock); 452 } 453 454 return; 455} 456 457/* 458 * _mtx_lock_spin: the tougher part of acquiring an MTX_SPIN lock. 459 * 460 * This is only called if we need to actually spin for the lock. Recursion 461 * is handled inline. 462 */ 463void 464_mtx_lock_spin(struct mtx *m, int opts, u_int mtx_intr, const char *file, 465 int line) 466{ 467 int i = 0; 468 469 if ((opts & MTX_QUIET) == 0) 470 CTR1(KTR_LOCK, "_mtx_lock_spin: %p spinning", m); 471 472 for (;;) { 473 if (_obtain_lock(m, curproc)) 474 break; 475 476 while (m->mtx_lock != MTX_UNOWNED) { 477 if (i++ < 1000000) 478 continue; 479 if (i++ < 6000000) 480 DELAY(1); 481#ifdef DDB 482 else if (!db_active) 483#else 484 else 485#endif 486 panic("spin lock %s held by %p for > 5 seconds", 487 m->mtx_description, (void *)m->mtx_lock); 488 } 489 } 490 491 m->mtx_saveintr = mtx_intr; 492 if ((opts & MTX_QUIET) == 0) 493 CTR1(KTR_LOCK, "_mtx_lock_spin: %p spin done", m); 494 495 return; 496} 497 498/* 499 * _mtx_unlock_sleep: the tougher part of releasing an MTX_DEF lock. 500 * 501 * We are only called here if the lock is recursed or contested (i.e. we 502 * need to wake up a blocked thread). 503 */ 504void 505_mtx_unlock_sleep(struct mtx *m, int opts, const char *file, int line) 506{ 507 struct proc *p, *p1; 508 struct mtx *m1; 509 int pri; 510 511 p = curproc; 512 513 if (mtx_recursed(m)) { 514 if (--(m->mtx_recurse) == 0) 515 atomic_clear_ptr(&m->mtx_lock, MTX_RECURSED); 516 if ((opts & MTX_QUIET) == 0) 517 CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p unrecurse", m); 518 return; 519 } 520 521 mtx_lock_spin(&sched_lock); 522 if ((opts & MTX_QUIET) == 0) 523 CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p contested", m); 524 525 p1 = TAILQ_FIRST(&m->mtx_blocked); 526 MPASS(p->p_magic == P_MAGIC); 527 MPASS(p1->p_magic == P_MAGIC); 528 529 TAILQ_REMOVE(&m->mtx_blocked, p1, p_procq); 530 531 if (TAILQ_EMPTY(&m->mtx_blocked)) { 532 LIST_REMOVE(m, mtx_contested); 533 _release_lock_quick(m); 534 if ((opts & MTX_QUIET) == 0) 535 CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p not held", m); 536 } else 537 atomic_store_rel_ptr(&m->mtx_lock, (void *)MTX_CONTESTED); 538 539 pri = PRI_MAX; 540 LIST_FOREACH(m1, &p->p_contested, mtx_contested) { 541 int cp = TAILQ_FIRST(&m1->mtx_blocked)->p_pri.pri_level; 542 if (cp < pri) 543 pri = cp; 544 } 545 546 if (pri > p->p_pri.pri_native) 547 pri = p->p_pri.pri_native; 548 SET_PRIO(p, pri); 549 550 if ((opts & MTX_QUIET) == 0) 551 CTR2(KTR_LOCK, "_mtx_unlock_sleep: %p contested setrunqueue %p", 552 m, p1); 553 554 p1->p_blocked = NULL; 555 p1->p_stat = SRUN; 556 setrunqueue(p1); 557 558 if ((opts & MTX_NOSWITCH) == 0 && p1->p_pri.pri_level < pri) { 559#ifdef notyet 560 if (p->p_ithd != NULL) { 561 struct ithd *it = p->p_ithd; 562 563 if (it->it_interrupted) { 564 if ((opts & MTX_QUIET) == 0) 565 CTR2(KTR_LOCK, 566 "_mtx_unlock_sleep: %p interrupted %p", 567 it, it->it_interrupted); 568 intr_thd_fixup(it); 569 } 570 } 571#endif 572 setrunqueue(p); 573 if ((opts & MTX_QUIET) == 0) 574 CTR2(KTR_LOCK, 575 "_mtx_unlock_sleep: %p switching out lock=%p", m, 576 (void *)m->mtx_lock); 577 578 mi_switch(); 579 if ((opts & MTX_QUIET) == 0) 580 CTR2(KTR_LOCK, "_mtx_unlock_sleep: %p resuming lock=%p", 581 m, (void *)m->mtx_lock); 582 } 583 584 mtx_unlock_spin(&sched_lock); 585 586 return; 587} 588 589/* 590 * All the unlocking of MTX_SPIN locks is done inline. 591 * See the _rel_spin_lock() macro for the details. 592 */ 593 594/* 595 * The backing function for the INVARIANTS-enabled mtx_assert() 596 */ 597#ifdef INVARIANT_SUPPORT 598void 599_mtx_assert(struct mtx *m, int what, const char *file, int line) 600{ 601 switch (what) { 602 case MA_OWNED: 603 case MA_OWNED | MA_RECURSED: 604 case MA_OWNED | MA_NOTRECURSED: 605 if (!mtx_owned(m)) 606 panic("mutex %s not owned at %s:%d", 607 m->mtx_description, file, line); 608 if (mtx_recursed(m)) { 609 if ((what & MA_NOTRECURSED) != 0) 610 panic("mutex %s recursed at %s:%d", 611 m->mtx_description, file, line); 612 } else if ((what & MA_RECURSED) != 0) { 613 panic("mutex %s unrecursed at %s:%d", 614 m->mtx_description, file, line); 615 } 616 break; 617 case MA_NOTOWNED: 618 if (mtx_owned(m)) 619 panic("mutex %s owned at %s:%d", 620 m->mtx_description, file, line); 621 break; 622 default: 623 panic("unknown mtx_assert at %s:%d", file, line); 624 } 625} 626#endif 627 628/* 629 * The MUTEX_DEBUG-enabled mtx_validate() 630 */ 631#define MV_DESTROY 0 /* validate before destory */ 632#define MV_INIT 1 /* validate before init */ 633 634#ifdef MUTEX_DEBUG 635 636int mtx_validate __P((struct mtx *, int)); 637 638int 639mtx_validate(struct mtx *m, int when) 640{ 641 struct mtx *mp; 642 int i; 643 int retval = 0; 644 645#ifdef WITNESS 646 if (witness_cold) 647 return 0; 648#endif 649 if (m == &all_mtx || cold) 650 return 0; 651 652 mtx_lock(&all_mtx); 653/* 654 * XXX - When kernacc() is fixed on the alpha to handle K0_SEG memory properly 655 * we can re-enable the kernacc() checks. 656 */ 657#ifndef __alpha__ 658 MPASS(kernacc((caddr_t)all_mtx.mtx_next, sizeof(uintptr_t), 659 VM_PROT_READ) == 1); 660#endif 661 MPASS(all_mtx.mtx_next->mtx_prev == &all_mtx); 662 for (i = 0, mp = all_mtx.mtx_next; mp != &all_mtx; mp = mp->mtx_next) { 663#ifndef __alpha__ 664 if (kernacc((caddr_t)mp->mtx_next, sizeof(uintptr_t), 665 VM_PROT_READ) != 1) { 666 panic("mtx_validate: mp=%p mp->mtx_next=%p", 667 mp, mp->mtx_next); 668 } 669#endif 670 i++; 671 if (i > mtx_cur_cnt) { 672 panic("mtx_validate: too many in chain, known=%d\n", 673 mtx_cur_cnt); 674 } 675 } 676 MPASS(i == mtx_cur_cnt); 677 switch (when) { 678 case MV_DESTROY: 679 for (mp = all_mtx.mtx_next; mp != &all_mtx; mp = mp->mtx_next) 680 if (mp == m) 681 break; 682 MPASS(mp == m); 683 break; 684 case MV_INIT: 685 for (mp = all_mtx.mtx_next; mp != &all_mtx; mp = mp->mtx_next) 686 if (mp == m) { 687 /* 688 * Not good. This mutex already exists. 689 */ 690 printf("re-initing existing mutex %s\n", 691 m->mtx_description); 692 MPASS(m->mtx_lock == MTX_UNOWNED); 693 retval = 1; 694 } 695 } 696 mtx_unlock(&all_mtx); 697 return (retval); 698} 699#endif 700 701/* 702 * Mutex initialization routine; initialize lock `m' of type contained in 703 * `opts' with options contained in `opts' and description `description.' 704 * Place on "all_mtx" queue. 705 */ 706void 707mtx_init(struct mtx *m, const char *description, int opts) 708{ 709 710 if ((opts & MTX_QUIET) == 0) 711 CTR2(KTR_LOCK, "mtx_init %p (%s)", m, description); 712 713#ifdef MUTEX_DEBUG 714 /* Diagnostic and error correction */ 715 if (mtx_validate(m, MV_INIT)) 716 return; 717#endif 718 719 bzero((void *)m, sizeof *m); 720 TAILQ_INIT(&m->mtx_blocked); 721 722#ifdef WITNESS 723 if (!witness_cold) { 724 m->mtx_debug = malloc(sizeof(struct mtx_debug), 725 M_WITNESS, M_NOWAIT | M_ZERO); 726 MPASS(m->mtx_debug != NULL); 727 } 728#endif 729 730 m->mtx_description = description; 731 m->mtx_flags = opts; 732 m->mtx_lock = MTX_UNOWNED; 733 734 /* Put on all mutex queue */ 735 mtx_lock(&all_mtx); 736 m->mtx_next = &all_mtx; 737 m->mtx_prev = all_mtx.mtx_prev; 738 m->mtx_prev->mtx_next = m; 739 all_mtx.mtx_prev = m; 740 if (++mtx_cur_cnt > mtx_max_cnt) 741 mtx_max_cnt = mtx_cur_cnt; 742 mtx_unlock(&all_mtx); 743 744#ifdef WITNESS 745 if (!witness_cold) 746 witness_init(m, opts); 747#endif 748} 749 750/* 751 * Remove lock `m' from all_mtx queue. 752 */ 753void 754mtx_destroy(struct mtx *m) 755{ 756 757#ifdef WITNESS 758 KASSERT(!witness_cold, ("%s: Cannot destroy while still cold\n", 759 __FUNCTION__)); 760#endif 761 762 CTR2(KTR_LOCK, "mtx_destroy %p (%s)", m, m->mtx_description); 763 764#ifdef MUTEX_DEBUG 765 if (m->mtx_next == NULL) 766 panic("mtx_destroy: %p (%s) already destroyed", 767 m, m->mtx_description); 768 769 if (!mtx_owned(m)) { 770 MPASS(m->mtx_lock == MTX_UNOWNED); 771 } else { 772 MPASS((m->mtx_lock & (MTX_RECURSED|MTX_CONTESTED)) == 0); 773 } 774 775 /* diagnostic */ 776 mtx_validate(m, MV_DESTROY); 777#endif 778 779#ifdef WITNESS 780 if (m->mtx_witness) 781 witness_destroy(m); 782#endif /* WITNESS */ 783 784 /* Remove from the all mutex queue */ 785 mtx_lock(&all_mtx); 786 m->mtx_next->mtx_prev = m->mtx_prev; 787 m->mtx_prev->mtx_next = m->mtx_next; 788 789#ifdef MUTEX_DEBUG 790 m->mtx_next = m->mtx_prev = NULL; 791#endif 792 793#ifdef WITNESS 794 free(m->mtx_debug, M_WITNESS); 795 m->mtx_debug = NULL; 796#endif 797 798 mtx_cur_cnt--; 799 mtx_unlock(&all_mtx); 800} 801 802 803/* 804 * The WITNESS-enabled diagnostic code. 805 */ 806#ifdef WITNESS 807static void 808witness_fixup(void *dummy __unused) 809{ 810 struct mtx *mp; 811 812 /* 813 * We have to release Giant before initializing its witness 814 * structure so that WITNESS doesn't get confused. 815 */ 816 mtx_unlock(&Giant); 817 mtx_assert(&Giant, MA_NOTOWNED); 818 819 mtx_lock(&all_mtx); 820 821 /* Iterate through all mutexes and finish up mutex initialization. */ 822 for (mp = all_mtx.mtx_next; mp != &all_mtx; mp = mp->mtx_next) { 823 824 mp->mtx_debug = malloc(sizeof(struct mtx_debug), 825 M_WITNESS, M_NOWAIT | M_ZERO); 826 MPASS(mp->mtx_debug != NULL); 827 828 witness_init(mp, mp->mtx_flags); 829 } 830 mtx_unlock(&all_mtx); 831 832 /* Mark the witness code as being ready for use. */ 833 atomic_store_rel_int(&witness_cold, 0); 834 835 mtx_lock(&Giant); 836} 837SYSINIT(wtnsfxup, SI_SUB_MUTEX, SI_ORDER_FIRST, witness_fixup, NULL) 838 839#define WITNESS_COUNT 200 840#define WITNESS_NCHILDREN 2 841 842int witness_watch = 1; 843 844struct witness { 845 struct witness *w_next; 846 const char *w_description; 847 const char *w_file; 848 int w_line; 849 struct witness *w_morechildren; 850 u_char w_childcnt; 851 u_char w_Giant_squawked:1; 852 u_char w_other_squawked:1; 853 u_char w_same_squawked:1; 854 u_char w_spin:1; /* MTX_SPIN type mutex. */ 855 u_int w_level; 856 struct witness *w_children[WITNESS_NCHILDREN]; 857}; 858 859struct witness_blessed { 860 char *b_lock1; 861 char *b_lock2; 862}; 863 864#ifdef DDB 865/* 866 * When DDB is enabled and witness_ddb is set to 1, it will cause the system to 867 * drop into kdebug() when: 868 * - a lock heirarchy violation occurs 869 * - locks are held when going to sleep. 870 */ 871int witness_ddb; 872#ifdef WITNESS_DDB 873TUNABLE_INT_DECL("debug.witness_ddb", 1, witness_ddb); 874#else 875TUNABLE_INT_DECL("debug.witness_ddb", 0, witness_ddb); 876#endif 877SYSCTL_INT(_debug, OID_AUTO, witness_ddb, CTLFLAG_RW, &witness_ddb, 0, ""); 878#endif /* DDB */ 879 880int witness_skipspin; 881#ifdef WITNESS_SKIPSPIN 882TUNABLE_INT_DECL("debug.witness_skipspin", 1, witness_skipspin); 883#else 884TUNABLE_INT_DECL("debug.witness_skipspin", 0, witness_skipspin); 885#endif 886SYSCTL_INT(_debug, OID_AUTO, witness_skipspin, CTLFLAG_RD, &witness_skipspin, 0, 887 ""); 888 889/* 890 * Witness-enabled globals 891 */ 892static struct mtx w_mtx; 893static struct witness *w_free; 894static struct witness *w_all; 895static int w_inited; 896static int witness_dead; /* fatal error, probably no memory */ 897 898static struct witness w_data[WITNESS_COUNT]; 899 900/* 901 * Internal witness routine prototypes 902 */ 903static struct witness *enroll(const char *description, int flag); 904static int itismychild(struct witness *parent, struct witness *child); 905static void removechild(struct witness *parent, struct witness *child); 906static int isitmychild(struct witness *parent, struct witness *child); 907static int isitmydescendant(struct witness *parent, struct witness *child); 908static int dup_ok(struct witness *); 909static int blessed(struct witness *, struct witness *); 910static void 911 witness_displaydescendants(void(*)(const char *fmt, ...), struct witness *); 912static void witness_leveldescendents(struct witness *parent, int level); 913static void witness_levelall(void); 914static struct witness * witness_get(void); 915static void witness_free(struct witness *m); 916 917static char *ignore_list[] = { 918 "witness lock", 919 NULL 920}; 921 922static char *spin_order_list[] = { 923#if defined(__i386__) && defined (SMP) 924 "com", 925#endif 926 "sio", 927#ifdef __i386__ 928 "cy", 929#endif 930 "ng_node", 931 "ng_worklist", 932 "ithread table lock", 933 "ithread list lock", 934 "sched lock", 935#ifdef __i386__ 936 "clk", 937#endif 938 "callout", 939 /* 940 * leaf locks 941 */ 942#ifdef SMP 943#ifdef __i386__ 944 "ap boot", 945 "imen", 946#endif 947 "smp rendezvous", 948#endif 949 NULL 950}; 951 952static char *order_list[] = { 953 "Giant", "proctree", "allproc", "process lock", "uidinfo hash", 954 "uidinfo struct", NULL, 955 NULL 956}; 957 958static char *dup_list[] = { 959 "process lock", 960 NULL 961}; 962 963static char *sleep_list[] = { 964 "Giant", 965 NULL 966}; 967 968/* 969 * Pairs of locks which have been blessed 970 * Don't complain about order problems with blessed locks 971 */ 972static struct witness_blessed blessed_list[] = { 973}; 974static int blessed_count = 975 sizeof(blessed_list) / sizeof(struct witness_blessed); 976 977static void 978witness_init(struct mtx *m, int flag) 979{ 980 m->mtx_witness = enroll(m->mtx_description, flag); 981} 982 983static void 984witness_destroy(struct mtx *m) 985{ 986 struct mtx *m1; 987 struct proc *p; 988 p = curproc; 989 LIST_FOREACH(m1, &p->p_heldmtx, mtx_held) { 990 if (m1 == m) { 991 LIST_REMOVE(m, mtx_held); 992 break; 993 } 994 } 995 return; 996 997} 998 999static void 1000witness_display(void(*prnt)(const char *fmt, ...)) 1001{ 1002 struct witness *w, *w1; 1003 int level, found; 1004 1005 KASSERT(!witness_cold, ("%s: witness_cold\n", __FUNCTION__)); 1006 witness_levelall(); 1007 1008 /* 1009 * First, handle sleep mutexes which have been acquired at least 1010 * once. 1011 */ 1012 prnt("Sleep mutexes:\n"); 1013 for (w = w_all; w; w = w->w_next) { 1014 if (w->w_file == NULL || w->w_spin) 1015 continue; 1016 for (w1 = w_all; w1; w1 = w1->w_next) { 1017 if (isitmychild(w1, w)) 1018 break; 1019 } 1020 if (w1 != NULL) 1021 continue; 1022 /* 1023 * This lock has no anscestors, display its descendants. 1024 */ 1025 witness_displaydescendants(prnt, w); 1026 } 1027 1028 /* 1029 * Now do spin mutexes which have been acquired at least once. 1030 */ 1031 prnt("\nSpin mutexes:\n"); 1032 level = 0; 1033 while (level < sizeof(spin_order_list) / sizeof(char *)) { 1034 found = 0; 1035 for (w = w_all; w; w = w->w_next) { 1036 if (w->w_file == NULL || !w->w_spin) 1037 continue; 1038 if (w->w_level == 1 << level) { 1039 witness_displaydescendants(prnt, w); 1040 level++; 1041 found = 1; 1042 } 1043 } 1044 if (found == 0) 1045 level++; 1046 } 1047 1048 /* 1049 * Finally, any mutexes which have not been acquired yet. 1050 */ 1051 prnt("\nMutexes which were never acquired:\n"); 1052 for (w = w_all; w; w = w->w_next) { 1053 if (w->w_file != NULL) 1054 continue; 1055 prnt("%s\n", w->w_description); 1056 } 1057} 1058 1059void 1060witness_enter(struct mtx *m, int flags, const char *file, int line) 1061{ 1062 struct witness *w, *w1; 1063 struct mtx *m1; 1064 struct proc *p; 1065 int i; 1066#ifdef DDB 1067 int go_into_ddb = 0; 1068#endif /* DDB */ 1069 1070 if (witness_cold || m->mtx_witness == NULL || panicstr) 1071 return; 1072 w = m->mtx_witness; 1073 p = curproc; 1074 1075 if (flags & MTX_SPIN) { 1076 if ((m->mtx_flags & MTX_SPIN) == 0) 1077 panic("mutex_enter: MTX_SPIN on MTX_DEF mutex %s @" 1078 " %s:%d", m->mtx_description, file, line); 1079 if (mtx_recursed(m)) { 1080 if ((m->mtx_flags & MTX_RECURSE) == 0) 1081 panic("mutex_enter: recursion on non-recursive" 1082 " mutex %s @ %s:%d", m->mtx_description, 1083 file, line); 1084 return; 1085 } 1086 mtx_lock_spin_flags(&w_mtx, MTX_QUIET); 1087 i = PCPU_GET(witness_spin_check); 1088 if (i != 0 && w->w_level < i) { 1089 mtx_unlock_spin_flags(&w_mtx, MTX_QUIET); 1090 panic("mutex_enter(%s:%x, MTX_SPIN) out of order @" 1091 " %s:%d already holding %s:%x", 1092 m->mtx_description, w->w_level, file, line, 1093 spin_order_list[ffs(i)-1], i); 1094 } 1095 PCPU_SET(witness_spin_check, i | w->w_level); 1096 mtx_unlock_spin_flags(&w_mtx, MTX_QUIET); 1097 p->p_spinlocks++; 1098 MPASS(p->p_spinlocks > 0); 1099 w->w_file = file; 1100 w->w_line = line; 1101 m->mtx_line = line; 1102 m->mtx_file = file; 1103 return; 1104 } 1105 if ((m->mtx_flags & MTX_SPIN) != 0) 1106 panic("mutex_enter: MTX_DEF on MTX_SPIN mutex %s @ %s:%d", 1107 m->mtx_description, file, line); 1108 1109 if (mtx_recursed(m)) { 1110 if ((m->mtx_flags & MTX_RECURSE) == 0) 1111 panic("mutex_enter: recursion on non-recursive" 1112 " mutex %s @ %s:%d", m->mtx_description, 1113 file, line); 1114 return; 1115 } 1116 if (witness_dead) 1117 goto out; 1118 if (cold) 1119 goto out; 1120 1121 if (p->p_spinlocks != 0) 1122 panic("blockable mtx_lock() of %s when not legal @ %s:%d", 1123 m->mtx_description, file, line); 1124 /* 1125 * Is this the first mutex acquired 1126 */ 1127 if ((m1 = LIST_FIRST(&p->p_heldmtx)) == NULL) 1128 goto out; 1129 1130 if ((w1 = m1->mtx_witness) == w) { 1131 if (w->w_same_squawked || dup_ok(w)) 1132 goto out; 1133 w->w_same_squawked = 1; 1134 printf("acquring duplicate lock of same type: \"%s\"\n", 1135 m->mtx_description); 1136 printf(" 1st @ %s:%d\n", w->w_file, w->w_line); 1137 printf(" 2nd @ %s:%d\n", file, line); 1138#ifdef DDB 1139 go_into_ddb = 1; 1140#endif /* DDB */ 1141 goto out; 1142 } 1143 MPASS(!mtx_owned(&w_mtx)); 1144 mtx_lock_spin_flags(&w_mtx, MTX_QUIET); 1145 /* 1146 * If we have a known higher number just say ok 1147 */ 1148 if (witness_watch > 1 && w->w_level > w1->w_level) { 1149 mtx_unlock_spin_flags(&w_mtx, MTX_QUIET); 1150 goto out; 1151 } 1152 if (isitmydescendant(m1->mtx_witness, w)) { 1153 mtx_unlock_spin_flags(&w_mtx, MTX_QUIET); 1154 goto out; 1155 } 1156 for (i = 0; m1 != NULL; m1 = LIST_NEXT(m1, mtx_held), i++) { 1157 1158 MPASS(i < 200); 1159 w1 = m1->mtx_witness; 1160 if (isitmydescendant(w, w1)) { 1161 mtx_unlock_spin_flags(&w_mtx, MTX_QUIET); 1162 if (blessed(w, w1)) 1163 goto out; 1164 if (m1 == &Giant) { 1165 if (w1->w_Giant_squawked) 1166 goto out; 1167 else 1168 w1->w_Giant_squawked = 1; 1169 } else { 1170 if (w1->w_other_squawked) 1171 goto out; 1172 else 1173 w1->w_other_squawked = 1; 1174 } 1175 printf("lock order reversal\n"); 1176 printf(" 1st %s last acquired @ %s:%d\n", 1177 w->w_description, w->w_file, w->w_line); 1178 printf(" 2nd %p %s @ %s:%d\n", 1179 m1, w1->w_description, w1->w_file, w1->w_line); 1180 printf(" 3rd %p %s @ %s:%d\n", 1181 m, w->w_description, file, line); 1182#ifdef DDB 1183 go_into_ddb = 1; 1184#endif /* DDB */ 1185 goto out; 1186 } 1187 } 1188 m1 = LIST_FIRST(&p->p_heldmtx); 1189 if (!itismychild(m1->mtx_witness, w)) 1190 mtx_unlock_spin_flags(&w_mtx, MTX_QUIET); 1191 1192out: 1193#ifdef DDB 1194 if (witness_ddb && go_into_ddb) 1195 Debugger("witness_enter"); 1196#endif /* DDB */ 1197 w->w_file = file; 1198 w->w_line = line; 1199 m->mtx_line = line; 1200 m->mtx_file = file; 1201 1202 /* 1203 * If this pays off it likely means that a mutex being witnessed 1204 * is acquired in hardclock. Put it in the ignore list. It is 1205 * likely not the mutex this assert fails on. 1206 */ 1207 MPASS(m->mtx_held.le_prev == NULL); 1208 LIST_INSERT_HEAD(&p->p_heldmtx, (struct mtx*)m, mtx_held); 1209} 1210 1211void 1212witness_try_enter(struct mtx *m, int flags, const char *file, int line) 1213{ 1214 struct proc *p; 1215 struct witness *w = m->mtx_witness; 1216 1217 if (witness_cold) 1218 return; 1219 if (panicstr) 1220 return; 1221 if (flags & MTX_SPIN) { 1222 if ((m->mtx_flags & MTX_SPIN) == 0) 1223 panic("mutex_try_enter: " 1224 "MTX_SPIN on MTX_DEF mutex %s @ %s:%d", 1225 m->mtx_description, file, line); 1226 if (mtx_recursed(m)) { 1227 if ((m->mtx_flags & MTX_RECURSE) == 0) 1228 panic("mutex_try_enter: recursion on" 1229 " non-recursive mutex %s @ %s:%d", 1230 m->mtx_description, file, line); 1231 return; 1232 } 1233 mtx_lock_spin_flags(&w_mtx, MTX_QUIET); 1234 PCPU_SET(witness_spin_check, 1235 PCPU_GET(witness_spin_check) | w->w_level); 1236 mtx_unlock_spin_flags(&w_mtx, MTX_QUIET); 1237 w->w_file = file; 1238 w->w_line = line; 1239 m->mtx_line = line; 1240 m->mtx_file = file; 1241 return; 1242 } 1243 1244 if ((m->mtx_flags & MTX_SPIN) != 0) 1245 panic("mutex_try_enter: MTX_DEF on MTX_SPIN mutex %s @ %s:%d", 1246 m->mtx_description, file, line); 1247 1248 if (mtx_recursed(m)) { 1249 if ((m->mtx_flags & MTX_RECURSE) == 0) 1250 panic("mutex_try_enter: recursion on non-recursive" 1251 " mutex %s @ %s:%d", m->mtx_description, file, 1252 line); 1253 return; 1254 } 1255 w->w_file = file; 1256 w->w_line = line; 1257 m->mtx_line = line; 1258 m->mtx_file = file; 1259 p = curproc; 1260 MPASS(m->mtx_held.le_prev == NULL); 1261 LIST_INSERT_HEAD(&p->p_heldmtx, (struct mtx*)m, mtx_held); 1262} 1263 1264void 1265witness_exit(struct mtx *m, int flags, const char *file, int line) 1266{ 1267 struct witness *w; 1268 struct proc *p; 1269 1270 if (witness_cold || m->mtx_witness == NULL || panicstr) 1271 return; 1272 w = m->mtx_witness; 1273 p = curproc; 1274 1275 if (flags & MTX_SPIN) { 1276 if ((m->mtx_flags & MTX_SPIN) == 0) 1277 panic("mutex_exit: MTX_SPIN on MTX_DEF mutex %s @" 1278 " %s:%d", m->mtx_description, file, line); 1279 if (mtx_recursed(m)) { 1280 if ((m->mtx_flags & MTX_RECURSE) == 0) 1281 panic("mutex_exit: recursion on non-recursive" 1282 " mutex %s @ %s:%d", m->mtx_description, 1283 file, line); 1284 return; 1285 } 1286 mtx_lock_spin_flags(&w_mtx, MTX_QUIET); 1287 PCPU_SET(witness_spin_check, 1288 PCPU_GET(witness_spin_check) & ~w->w_level); 1289 mtx_unlock_spin_flags(&w_mtx, MTX_QUIET); 1290 MPASS(p->p_spinlocks > 0); 1291 p->p_spinlocks--; 1292 return; 1293 } 1294 if ((m->mtx_flags & MTX_SPIN) != 0) 1295 panic("mutex_exit: MTX_DEF on MTX_SPIN mutex %s @ %s:%d", 1296 m->mtx_description, file, line); 1297 1298 if (mtx_recursed(m)) { 1299 if ((m->mtx_flags & MTX_RECURSE) == 0) 1300 panic("mutex_exit: recursion on non-recursive" 1301 " mutex %s @ %s:%d", m->mtx_description, 1302 file, line); 1303 return; 1304 } 1305 1306 if ((flags & MTX_NOSWITCH) == 0 && p->p_spinlocks != 0 && !cold) 1307 panic("switchable mtx_unlock() of %s when not legal @ %s:%d", 1308 m->mtx_description, file, line); 1309 LIST_REMOVE(m, mtx_held); 1310 m->mtx_held.le_prev = NULL; 1311} 1312 1313int 1314witness_sleep(int check_only, struct mtx *mtx, const char *file, int line) 1315{ 1316 struct mtx *m; 1317 struct proc *p; 1318 char **sleep; 1319 int n = 0; 1320 1321 KASSERT(!witness_cold, ("%s: witness_cold\n", __FUNCTION__)); 1322 p = curproc; 1323 LIST_FOREACH(m, &p->p_heldmtx, mtx_held) { 1324 if (m == mtx) 1325 continue; 1326 for (sleep = sleep_list; *sleep!= NULL; sleep++) 1327 if (strcmp(m->mtx_description, *sleep) == 0) 1328 goto next; 1329 if (n == 0) 1330 printf("Whee!\n"); 1331 printf("%s:%d: %s with \"%s\" locked from %s:%d\n", 1332 file, line, check_only ? "could sleep" : "sleeping", 1333 m->mtx_description, 1334 m->mtx_witness->w_file, m->mtx_witness->w_line); 1335 n++; 1336 next: 1337 } 1338#ifdef DDB 1339 if (witness_ddb && n) 1340 Debugger("witness_sleep"); 1341#endif /* DDB */ 1342 return (n); 1343} 1344 1345static struct witness * 1346enroll(const char *description, int flag) 1347{ 1348 int i; 1349 struct witness *w, *w1; 1350 char **ignore; 1351 char **order; 1352 1353 if (!witness_watch) 1354 return (NULL); 1355 for (ignore = ignore_list; *ignore != NULL; ignore++) 1356 if (strcmp(description, *ignore) == 0) 1357 return (NULL); 1358 1359 if (w_inited == 0) { 1360 mtx_init(&w_mtx, "witness lock", MTX_SPIN); 1361 for (i = 0; i < WITNESS_COUNT; i++) { 1362 w = &w_data[i]; 1363 witness_free(w); 1364 } 1365 w_inited = 1; 1366 for (order = order_list; *order != NULL; order++) { 1367 w = enroll(*order, MTX_DEF); 1368 w->w_file = "order list"; 1369 for (order++; *order != NULL; order++) { 1370 w1 = enroll(*order, MTX_DEF); 1371 w1->w_file = "order list"; 1372 itismychild(w, w1); 1373 w = w1; 1374 } 1375 } 1376 } 1377 if ((flag & MTX_SPIN) && witness_skipspin) 1378 return (NULL); 1379 mtx_lock_spin_flags(&w_mtx, MTX_QUIET); 1380 for (w = w_all; w; w = w->w_next) { 1381 if (strcmp(description, w->w_description) == 0) { 1382 mtx_unlock_spin_flags(&w_mtx, MTX_QUIET); 1383 return (w); 1384 } 1385 } 1386 if ((w = witness_get()) == NULL) 1387 return (NULL); 1388 w->w_next = w_all; 1389 w_all = w; 1390 w->w_description = description; 1391 mtx_unlock_spin_flags(&w_mtx, MTX_QUIET); 1392 if (flag & MTX_SPIN) { 1393 w->w_spin = 1; 1394 1395 i = 1; 1396 for (order = spin_order_list; *order != NULL; order++) { 1397 if (strcmp(description, *order) == 0) 1398 break; 1399 i <<= 1; 1400 } 1401 if (*order == NULL) 1402 panic("spin lock %s not in order list", description); 1403 w->w_level = i; 1404 } 1405 1406 return (w); 1407} 1408 1409static int 1410itismychild(struct witness *parent, struct witness *child) 1411{ 1412 static int recursed; 1413 1414 /* 1415 * Insert "child" after "parent" 1416 */ 1417 while (parent->w_morechildren) 1418 parent = parent->w_morechildren; 1419 1420 if (parent->w_childcnt == WITNESS_NCHILDREN) { 1421 if ((parent->w_morechildren = witness_get()) == NULL) 1422 return (1); 1423 parent = parent->w_morechildren; 1424 } 1425 MPASS(child != NULL); 1426 parent->w_children[parent->w_childcnt++] = child; 1427 /* 1428 * now prune whole tree 1429 */ 1430 if (recursed) 1431 return (0); 1432 recursed = 1; 1433 for (child = w_all; child != NULL; child = child->w_next) { 1434 for (parent = w_all; parent != NULL; 1435 parent = parent->w_next) { 1436 if (!isitmychild(parent, child)) 1437 continue; 1438 removechild(parent, child); 1439 if (isitmydescendant(parent, child)) 1440 continue; 1441 itismychild(parent, child); 1442 } 1443 } 1444 recursed = 0; 1445 witness_levelall(); 1446 return (0); 1447} 1448 1449static void 1450removechild(struct witness *parent, struct witness *child) 1451{ 1452 struct witness *w, *w1; 1453 int i; 1454 1455 for (w = parent; w != NULL; w = w->w_morechildren) 1456 for (i = 0; i < w->w_childcnt; i++) 1457 if (w->w_children[i] == child) 1458 goto found; 1459 return; 1460found: 1461 for (w1 = w; w1->w_morechildren != NULL; w1 = w1->w_morechildren) 1462 continue; 1463 w->w_children[i] = w1->w_children[--w1->w_childcnt]; 1464 MPASS(w->w_children[i] != NULL); 1465 1466 if (w1->w_childcnt != 0) 1467 return; 1468 1469 if (w1 == parent) 1470 return; 1471 for (w = parent; w->w_morechildren != w1; w = w->w_morechildren) 1472 continue; 1473 w->w_morechildren = 0; 1474 witness_free(w1); 1475} 1476 1477static int 1478isitmychild(struct witness *parent, struct witness *child) 1479{ 1480 struct witness *w; 1481 int i; 1482 1483 for (w = parent; w != NULL; w = w->w_morechildren) { 1484 for (i = 0; i < w->w_childcnt; i++) { 1485 if (w->w_children[i] == child) 1486 return (1); 1487 } 1488 } 1489 return (0); 1490} 1491 1492static int 1493isitmydescendant(struct witness *parent, struct witness *child) 1494{ 1495 struct witness *w; 1496 int i; 1497 int j; 1498 1499 for (j = 0, w = parent; w != NULL; w = w->w_morechildren, j++) { 1500 MPASS(j < 1000); 1501 for (i = 0; i < w->w_childcnt; i++) { 1502 if (w->w_children[i] == child) 1503 return (1); 1504 } 1505 for (i = 0; i < w->w_childcnt; i++) { 1506 if (isitmydescendant(w->w_children[i], child)) 1507 return (1); 1508 } 1509 } 1510 return (0); 1511} 1512 1513void 1514witness_levelall (void) 1515{ 1516 struct witness *w, *w1; 1517 1518 for (w = w_all; w; w = w->w_next) 1519 if (!(w->w_spin)) 1520 w->w_level = 0; 1521 for (w = w_all; w; w = w->w_next) { 1522 if (w->w_spin) 1523 continue; 1524 for (w1 = w_all; w1; w1 = w1->w_next) { 1525 if (isitmychild(w1, w)) 1526 break; 1527 } 1528 if (w1 != NULL) 1529 continue; 1530 witness_leveldescendents(w, 0); 1531 } 1532} 1533 1534static void 1535witness_leveldescendents(struct witness *parent, int level) 1536{ 1537 int i; 1538 struct witness *w; 1539 1540 if (parent->w_level < level) 1541 parent->w_level = level; 1542 level++; 1543 for (w = parent; w != NULL; w = w->w_morechildren) 1544 for (i = 0; i < w->w_childcnt; i++) 1545 witness_leveldescendents(w->w_children[i], level); 1546} 1547 1548static void 1549witness_displaydescendants(void(*prnt)(const char *fmt, ...), 1550 struct witness *parent) 1551{ 1552 struct witness *w; 1553 int i; 1554 int level; 1555 1556 level = parent->w_spin ? ffs(parent->w_level) : parent->w_level; 1557 1558 prnt("%d", level); 1559 if (level < 10) 1560 prnt(" "); 1561 for (i = 0; i < level; i++) 1562 prnt(" "); 1563 prnt("%s", parent->w_description); 1564 if (parent->w_file != NULL) 1565 prnt(" -- last acquired @ %s:%d\n", parent->w_file, 1566 parent->w_line); 1567 1568 for (w = parent; w != NULL; w = w->w_morechildren) 1569 for (i = 0; i < w->w_childcnt; i++) 1570 witness_displaydescendants(prnt, w->w_children[i]); 1571 } 1572 1573static int 1574dup_ok(struct witness *w) 1575{ 1576 char **dup; 1577 1578 for (dup = dup_list; *dup!= NULL; dup++) 1579 if (strcmp(w->w_description, *dup) == 0) 1580 return (1); 1581 return (0); 1582} 1583 1584static int 1585blessed(struct witness *w1, struct witness *w2) 1586{ 1587 int i; 1588 struct witness_blessed *b; 1589 1590 for (i = 0; i < blessed_count; i++) { 1591 b = &blessed_list[i]; 1592 if (strcmp(w1->w_description, b->b_lock1) == 0) { 1593 if (strcmp(w2->w_description, b->b_lock2) == 0) 1594 return (1); 1595 continue; 1596 } 1597 if (strcmp(w1->w_description, b->b_lock2) == 0) 1598 if (strcmp(w2->w_description, b->b_lock1) == 0) 1599 return (1); 1600 } 1601 return (0); 1602} 1603 1604static struct witness * 1605witness_get() 1606{ 1607 struct witness *w; 1608 1609 if ((w = w_free) == NULL) { 1610 witness_dead = 1; 1611 mtx_unlock_spin_flags(&w_mtx, MTX_QUIET); 1612 printf("witness exhausted\n"); 1613 return (NULL); 1614 } 1615 w_free = w->w_next; 1616 bzero(w, sizeof(*w)); 1617 return (w); 1618} 1619 1620static void 1621witness_free(struct witness *w) 1622{ 1623 w->w_next = w_free; 1624 w_free = w; 1625} 1626 1627int 1628witness_list(struct proc *p) 1629{ 1630 struct mtx *m; 1631 int nheld; 1632 1633 KASSERT(!witness_cold, ("%s: witness_cold\n", __FUNCTION__)); 1634 nheld = 0; 1635 LIST_FOREACH(m, &p->p_heldmtx, mtx_held) { 1636 printf("\t\"%s\" (%p) locked at %s:%d\n", 1637 m->mtx_description, m, 1638 m->mtx_witness->w_file, m->mtx_witness->w_line); 1639 nheld++; 1640 } 1641 1642 return (nheld); 1643} 1644 1645#ifdef DDB 1646 1647DB_SHOW_COMMAND(mutexes, db_witness_list) 1648{ 1649 1650 witness_list(curproc); 1651} 1652 1653DB_SHOW_COMMAND(witness, db_witness_display) 1654{ 1655 1656 witness_display(db_printf); 1657} 1658#endif 1659 1660void 1661witness_save(struct mtx *m, const char **filep, int *linep) 1662{ 1663 1664 KASSERT(!witness_cold, ("%s: witness_cold\n", __FUNCTION__)); 1665 if (m->mtx_witness == NULL) 1666 return; 1667 1668 *filep = m->mtx_witness->w_file; 1669 *linep = m->mtx_witness->w_line; 1670} 1671 1672void 1673witness_restore(struct mtx *m, const char *file, int line) 1674{ 1675 1676 KASSERT(!witness_cold, ("%s: witness_cold\n", __FUNCTION__)); 1677 if (m->mtx_witness == NULL) 1678 return; 1679 1680 m->mtx_witness->w_file = file; 1681 m->mtx_witness->w_line = line; 1682} 1683 1684#endif /* WITNESS */ 1685