kern_mutex.c revision 67548
1254721Semaste/*- 2254721Semaste * Copyright (c) 1998 Berkeley Software Design, Inc. All rights reserved. 3254721Semaste * 4254721Semaste * Redistribution and use in source and binary forms, with or without 5254721Semaste * modification, are permitted provided that the following conditions 6254721Semaste * are met: 7254721Semaste * 1. Redistributions of source code must retain the above copyright 8254721Semaste * notice, this list of conditions and the following disclaimer. 9254721Semaste * 2. Redistributions in binary form must reproduce the above copyright 10254721Semaste * notice, this list of conditions and the following disclaimer in the 11254721Semaste * documentation and/or other materials provided with the distribution. 12254721Semaste * 3. Berkeley Software Design Inc's name may not be used to endorse or 13254721Semaste * promote products derived from this software without specific prior 14254721Semaste * written permission. 15254721Semaste * 16254721Semaste * THIS SOFTWARE IS PROVIDED BY BERKELEY SOFTWARE DESIGN INC ``AS IS'' AND 17254721Semaste * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 18254721Semaste * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 19254721Semaste * ARE DISCLAIMED. IN NO EVENT SHALL BERKELEY SOFTWARE DESIGN INC BE LIABLE 20254721Semaste * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 21254721Semaste * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 22254721Semaste * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 23254721Semaste * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 24254721Semaste * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 25254721Semaste * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26254721Semaste * SUCH DAMAGE. 27254721Semaste * 28254721Semaste * from BSDI $Id: mutex_witness.c,v 1.1.2.20 2000/04/27 03:10:27 cp Exp $ 29254721Semaste * and BSDI $Id: synch_machdep.c,v 2.3.2.39 2000/04/27 03:10:25 cp Exp $ 30254721Semaste * $FreeBSD: head/sys/kern/kern_mutex.c 67548 2000-10-25 04:37:54Z jhb $ 31254721Semaste */ 32254721Semaste 33254721Semaste/* 34254721Semaste * Main Entry: witness 35254721Semaste * Pronunciation: 'wit-n&s 36254721Semaste * Function: noun 37254721Semaste * Etymology: Middle English witnesse, from Old English witnes knowledge, 38254721Semaste * testimony, witness, from 2wit 39254721Semaste * Date: before 12th century 40254721Semaste * 1 : attestation of a fact or event : TESTIMONY 41254721Semaste * 2 : one that gives evidence; specifically : one who testifies in 42254721Semaste * a cause or before a judicial tribunal 43254721Semaste * 3 : one asked to be present at a transaction so as to be able to 44254721Semaste * testify to its having taken place 45254721Semaste * 4 : one who has personal knowledge of something 46254721Semaste * 5 a : something serving as evidence or proof : SIGN 47254721Semaste * b : public affirmation by word or example of usually 48254721Semaste * religious faith or conviction <the heroic witness to divine 49254721Semaste * life -- Pilot> 50254721Semaste * 6 capitalized : a member of the Jehovah's Witnesses 51254721Semaste */ 52254721Semaste 53254721Semaste#include <sys/param.h> 54254721Semaste#include <sys/bus.h> 55254721Semaste#include <sys/kernel.h> 56254721Semaste#include <sys/malloc.h> 57254721Semaste#include <sys/proc.h> 58254721Semaste#include <sys/systm.h> 59254721Semaste#include <sys/vmmeter.h> 60254721Semaste#include <sys/ktr.h> 61254721Semaste 62254721Semaste#include <machine/atomic.h> 63254721Semaste#include <machine/bus.h> 64254721Semaste#include <machine/clock.h> 65254721Semaste#include <machine/cpu.h> 66254721Semaste 67254721Semaste#include <vm/vm.h> 68254721Semaste#include <vm/vm_extern.h> 69254721Semaste 70254721Semaste#define _KERN_MUTEX_C_ /* Cause non-inlined mtx_*() to be compiled. */ 71254721Semaste#include <sys/mutex.h> 72254721Semaste 73254721Semaste/* 74254721Semaste * Machine independent bits of the mutex implementation 75254721Semaste */ 76254721Semaste/* All mutexes in system (used for debug/panic) */ 77254721Semaste#ifdef MUTEX_DEBUG 78254721Semastestatic struct mtx_debug all_mtx_debug = { NULL, {NULL, NULL}, NULL, 0, 79254721Semaste "All mutexes queue head" }; 80254721Semastestatic struct mtx all_mtx = { MTX_UNOWNED, 0, 0, &all_mtx_debug, 81254721Semaste TAILQ_HEAD_INITIALIZER(all_mtx.mtx_blocked), 82254721Semaste { NULL, NULL }, &all_mtx, &all_mtx }; 83254721Semaste#else /* MUTEX_DEBUG */ 84254721Semastestatic struct mtx all_mtx = { MTX_UNOWNED, 0, 0, "All mutexes queue head", 85254721Semaste TAILQ_HEAD_INITIALIZER(all_mtx.mtx_blocked), 86254721Semaste { NULL, NULL }, &all_mtx, &all_mtx }; 87254721Semaste#endif /* MUTEX_DEBUG */ 88254721Semaste 89254721Semastestatic int mtx_cur_cnt; 90254721Semastestatic int mtx_max_cnt; 91254721Semaste 92254721Semastevoid _mtx_enter_giant_def(void); 93254721Semastevoid _mtx_exit_giant_def(void); 94254721Semastestatic void propagate_priority(struct proc *) __unused; 95254721Semaste 96254721Semaste#define mtx_unowned(m) ((m)->mtx_lock == MTX_UNOWNED) 97254721Semaste#define mtx_owner(m) (mtx_unowned(m) ? NULL \ 98254721Semaste : (struct proc *)((m)->mtx_lock & MTX_FLAGMASK)) 99254721Semaste 100254721Semaste#define RETIP(x) *(((uintptr_t *)(&x)) - 1) 101254721Semaste#define SET_PRIO(p, pri) (p)->p_priority = (pri) 102254721Semaste 103254721Semaste/* 104254721Semaste * XXX Temporary, for use from assembly language 105254721Semaste */ 106254721Semaste 107254721Semastevoid 108254721Semaste_mtx_enter_giant_def(void) 109254721Semaste{ 110254721Semaste 111254721Semaste mtx_enter(&Giant, MTX_DEF); 112254721Semaste} 113254721Semaste 114254721Semastevoid 115254721Semaste_mtx_exit_giant_def(void) 116254721Semaste{ 117254721Semaste 118254721Semaste mtx_exit(&Giant, MTX_DEF); 119254721Semaste} 120254721Semaste 121254721Semastestatic void 122254721Semastepropagate_priority(struct proc *p) 123254721Semaste{ 124254721Semaste int pri = p->p_priority; 125254721Semaste struct mtx *m = p->p_blocked; 126254721Semaste 127254721Semaste for (;;) { 128254721Semaste struct proc *p1; 129254721Semaste 130254721Semaste p = mtx_owner(m); 131254721Semaste 132254721Semaste if (p == NULL) { 133254721Semaste /* 134254721Semaste * This really isn't quite right. Really 135254721Semaste * ought to bump priority of process that 136254721Semaste * next acquires the mutex. 137254721Semaste */ 138254721Semaste MPASS(m->mtx_lock == MTX_CONTESTED); 139254721Semaste return; 140254721Semaste } 141254721Semaste MPASS(p->p_magic == P_MAGIC); 142254721Semaste if (p->p_priority <= pri) 143254721Semaste return; 144254721Semaste /* 145254721Semaste * If lock holder is actually running, just bump priority. 146254721Semaste */ 147254721Semaste if (TAILQ_NEXT(p, p_procq) == NULL) { 148254721Semaste MPASS(p->p_stat == SRUN || p->p_stat == SZOMB); 149254721Semaste SET_PRIO(p, pri); 150254721Semaste return; 151254721Semaste } 152254721Semaste /* 153254721Semaste * If on run queue move to new run queue, and 154254721Semaste * quit. 155254721Semaste */ 156254721Semaste if (p->p_stat == SRUN) { 157254721Semaste MPASS(p->p_blocked == NULL); 158254721Semaste remrunqueue(p); 159254721Semaste SET_PRIO(p, pri); 160254721Semaste setrunqueue(p); 161254721Semaste return; 162254721Semaste } 163254721Semaste 164254721Semaste /* 165254721Semaste * If we aren't blocked on a mutex, give up and quit. 166254721Semaste */ 167254721Semaste if (p->p_stat != SMTX) { 168254721Semaste printf( 169254721Semaste "XXX: process %d(%s):%d holds %s but isn't blocked on a mutex\n", 170254721Semaste p->p_pid, p->p_comm, p->p_stat, m->mtx_description); 171254721Semaste return; 172254721Semaste } 173254721Semaste 174254721Semaste /* 175254721Semaste * Pick up the mutex that p is blocked on. 176254721Semaste */ 177254721Semaste m = p->p_blocked; 178254721Semaste MPASS(m != NULL); 179254721Semaste 180254721Semaste printf("XXX: process %d(%s) is blocked on %s\n", p->p_pid, 181 p->p_comm, m->mtx_description); 182 /* 183 * Check if the proc needs to be moved up on 184 * the blocked chain 185 */ 186 if ((p1 = TAILQ_PREV(p, rq, p_procq)) == NULL || 187 p1->p_priority <= pri) { 188 if (p1) 189 printf( 190 "XXX: previous process %d(%s) has higher priority\n", 191 p->p_pid, p->p_comm); 192 else 193 printf("XXX: process at head of run queue\n"); 194 continue; 195 } 196 197 /* 198 * Remove proc from blocked chain 199 */ 200 TAILQ_REMOVE(&m->mtx_blocked, p, p_procq); 201 TAILQ_FOREACH(p1, &m->mtx_blocked, p_procq) { 202 MPASS(p1->p_magic == P_MAGIC); 203 if (p1->p_priority > pri) 204 break; 205 } 206 if (p1) 207 TAILQ_INSERT_BEFORE(p1, p, p_procq); 208 else 209 TAILQ_INSERT_TAIL(&m->mtx_blocked, p, p_procq); 210 CTR4(KTR_LOCK, 211 "propagate priority: p 0x%p moved before 0x%p on [0x%p] %s", 212 p, p1, m, m->mtx_description); 213 } 214} 215 216void 217mtx_enter_hard(struct mtx *m, int type, int saveintr) 218{ 219 struct proc *p = CURPROC; 220 struct timeval new_switchtime; 221 222 KASSERT(p != NULL, ("curproc is NULL in mutex")); 223 224 switch (type) { 225 case MTX_DEF: 226 if ((m->mtx_lock & MTX_FLAGMASK) == (uintptr_t)p) { 227 m->mtx_recurse++; 228 atomic_set_ptr(&m->mtx_lock, MTX_RECURSE); 229 CTR1(KTR_LOCK, "mtx_enter: 0x%p recurse", m); 230 return; 231 } 232 CTR3(KTR_LOCK, "mtx_enter: 0x%p contested (lock=%p) [0x%p]", 233 m, (void *)m->mtx_lock, (void *)RETIP(m)); 234 while (!_obtain_lock(m, p)) { 235 uintptr_t v; 236 struct proc *p1; 237 238 mtx_enter(&sched_lock, MTX_SPIN | MTX_RLIKELY); 239 /* 240 * check if the lock has been released while 241 * waiting for the schedlock. 242 */ 243 if ((v = m->mtx_lock) == MTX_UNOWNED) { 244 mtx_exit(&sched_lock, MTX_SPIN); 245 continue; 246 } 247 /* 248 * The mutex was marked contested on release. This 249 * means that there are processes blocked on it. 250 */ 251 if (v == MTX_CONTESTED) { 252 p1 = TAILQ_FIRST(&m->mtx_blocked); 253 KASSERT(p1 != NULL, ("contested mutex has no contesters")); 254 KASSERT(p != NULL, ("curproc is NULL for contested mutex")); 255 m->mtx_lock = (uintptr_t)p | MTX_CONTESTED; 256 if (p1->p_priority < p->p_priority) { 257 SET_PRIO(p, p1->p_priority); 258 } 259 mtx_exit(&sched_lock, MTX_SPIN); 260 return; 261 } 262 /* 263 * If the mutex isn't already contested and 264 * a failure occurs setting the contested bit the 265 * mutex was either release or the 266 * state of the RECURSION bit changed. 267 */ 268 if ((v & MTX_CONTESTED) == 0 && 269 !atomic_cmpset_ptr(&m->mtx_lock, (void *)v, 270 (void *)(v | MTX_CONTESTED))) { 271 mtx_exit(&sched_lock, MTX_SPIN); 272 continue; 273 } 274 275 /* We definitely have to sleep for this lock */ 276 mtx_assert(m, MA_NOTOWNED); 277 278#ifdef notyet 279 /* 280 * If we're borrowing an interrupted thread's VM 281 * context must clean up before going to sleep. 282 */ 283 if (p->p_flag & (P_ITHD | P_SITHD)) { 284 ithd_t *it = (ithd_t *)p; 285 286 if (it->it_interrupted) { 287 CTR2(KTR_LOCK, 288 "mtx_enter: 0x%x interrupted 0x%x", 289 it, it->it_interrupted); 290 intr_thd_fixup(it); 291 } 292 } 293#endif 294 295 /* Put us on the list of procs blocked on this mutex */ 296 if (TAILQ_EMPTY(&m->mtx_blocked)) { 297 p1 = (struct proc *)(m->mtx_lock & 298 MTX_FLAGMASK); 299 LIST_INSERT_HEAD(&p1->p_contested, m, 300 mtx_contested); 301 TAILQ_INSERT_TAIL(&m->mtx_blocked, p, p_procq); 302 } else { 303 TAILQ_FOREACH(p1, &m->mtx_blocked, p_procq) 304 if (p1->p_priority > p->p_priority) 305 break; 306 if (p1) 307 TAILQ_INSERT_BEFORE(p1, p, p_procq); 308 else 309 TAILQ_INSERT_TAIL(&m->mtx_blocked, p, 310 p_procq); 311 } 312 313 p->p_blocked = m; /* Who we're blocked on */ 314 p->p_stat = SMTX; 315#if 0 316 propagate_priority(p); 317#endif 318 CTR3(KTR_LOCK, "mtx_enter: p 0x%p blocked on [0x%p] %s", 319 p, m, m->mtx_description); 320 /* 321 * Blatantly copied from mi_switch nearly verbatim. 322 * When Giant goes away and we stop dinking with it 323 * in mi_switch, we can go back to calling mi_switch 324 * directly here. 325 */ 326 327 /* 328 * Compute the amount of time during which the current 329 * process was running, and add that to its total so 330 * far. 331 */ 332 microuptime(&new_switchtime); 333 if (timevalcmp(&new_switchtime, &switchtime, <)) { 334 printf( 335 "microuptime() went backwards (%ld.%06ld -> %ld.%06ld)\n", 336 switchtime.tv_sec, switchtime.tv_usec, 337 new_switchtime.tv_sec, 338 new_switchtime.tv_usec); 339 new_switchtime = switchtime; 340 } else { 341 p->p_runtime += (new_switchtime.tv_usec - 342 switchtime.tv_usec) + 343 (new_switchtime.tv_sec - switchtime.tv_sec) * 344 (int64_t)1000000; 345 } 346 347 /* 348 * Pick a new current process and record its start time. 349 */ 350 cnt.v_swtch++; 351 switchtime = new_switchtime; 352 cpu_switch(); 353 if (switchtime.tv_sec == 0) 354 microuptime(&switchtime); 355 switchticks = ticks; 356 CTR3(KTR_LOCK, 357 "mtx_enter: p 0x%p free from blocked on [0x%p] %s", 358 p, m, m->mtx_description); 359 mtx_exit(&sched_lock, MTX_SPIN); 360 } 361 return; 362 case MTX_SPIN: 363 case MTX_SPIN | MTX_FIRST: 364 case MTX_SPIN | MTX_TOPHALF: 365 { 366 int i = 0; 367 368 if (m->mtx_lock == (uintptr_t)p) { 369 m->mtx_recurse++; 370 return; 371 } 372 CTR1(KTR_LOCK, "mtx_enter: %p spinning", m); 373 for (;;) { 374 if (_obtain_lock(m, p)) 375 break; 376 while (m->mtx_lock != MTX_UNOWNED) { 377 if (i++ < 1000000) 378 continue; 379 if (i++ < 6000000) 380 DELAY (1); 381#ifdef DDB 382 else if (!db_active) 383#else 384 else 385#endif 386 panic( 387 "spin lock %s held by 0x%p for > 5 seconds", 388 m->mtx_description, 389 (void *)m->mtx_lock); 390 } 391 } 392 393#ifdef MUTEX_DEBUG 394 if (type != MTX_SPIN) 395 m->mtx_saveintr = 0xbeefface; 396 else 397#endif 398 m->mtx_saveintr = saveintr; 399 CTR1(KTR_LOCK, "mtx_enter: 0x%p spin done", m); 400 return; 401 } 402 } 403} 404 405void 406mtx_exit_hard(struct mtx *m, int type) 407{ 408 struct proc *p, *p1; 409 struct mtx *m1; 410 int pri; 411 412 p = CURPROC; 413 switch (type) { 414 case MTX_DEF: 415 case MTX_DEF | MTX_NOSWITCH: 416 if (m->mtx_recurse != 0) { 417 if (--(m->mtx_recurse) == 0) 418 atomic_clear_ptr(&m->mtx_lock, MTX_RECURSE); 419 CTR1(KTR_LOCK, "mtx_exit: 0x%p unrecurse", m); 420 return; 421 } 422 mtx_enter(&sched_lock, MTX_SPIN); 423 CTR1(KTR_LOCK, "mtx_exit: 0x%p contested", m); 424 p1 = TAILQ_FIRST(&m->mtx_blocked); 425 MPASS(p->p_magic == P_MAGIC); 426 MPASS(p1->p_magic == P_MAGIC); 427 TAILQ_REMOVE(&m->mtx_blocked, p1, p_procq); 428 if (TAILQ_EMPTY(&m->mtx_blocked)) { 429 LIST_REMOVE(m, mtx_contested); 430 _release_lock_quick(m); 431 CTR1(KTR_LOCK, "mtx_exit: 0x%p not held", m); 432 } else 433 m->mtx_lock = MTX_CONTESTED; 434 pri = MAXPRI; 435 LIST_FOREACH(m1, &p->p_contested, mtx_contested) { 436 int cp = TAILQ_FIRST(&m1->mtx_blocked)->p_priority; 437 if (cp < pri) 438 pri = cp; 439 } 440 if (pri > p->p_nativepri) 441 pri = p->p_nativepri; 442 SET_PRIO(p, pri); 443 CTR2(KTR_LOCK, "mtx_exit: 0x%p contested setrunqueue 0x%p", 444 m, p1); 445 p1->p_blocked = NULL; 446 p1->p_stat = SRUN; 447 setrunqueue(p1); 448 if ((type & MTX_NOSWITCH) == 0 && p1->p_priority < pri) { 449#ifdef notyet 450 if (p->p_flag & (P_ITHD | P_SITHD)) { 451 ithd_t *it = (ithd_t *)p; 452 453 if (it->it_interrupted) { 454 CTR2(KTR_LOCK, 455 "mtx_exit: 0x%x interruped 0x%x", 456 it, it->it_interrupted); 457 intr_thd_fixup(it); 458 } 459 } 460#endif 461 setrunqueue(p); 462 CTR2(KTR_LOCK, "mtx_exit: 0x%p switching out lock=0x%p", 463 m, (void *)m->mtx_lock); 464 mi_switch(); 465 CTR2(KTR_LOCK, "mtx_exit: 0x%p resuming lock=0x%p", 466 m, (void *)m->mtx_lock); 467 } 468 mtx_exit(&sched_lock, MTX_SPIN); 469 break; 470 case MTX_SPIN: 471 case MTX_SPIN | MTX_FIRST: 472 if (m->mtx_recurse != 0) { 473 m->mtx_recurse--; 474 return; 475 } 476 MPASS(mtx_owned(m)); 477 _release_lock_quick(m); 478 if (type & MTX_FIRST) 479 enable_intr(); /* XXX is this kosher? */ 480 else { 481 MPASS(m->mtx_saveintr != 0xbeefface); 482 restore_intr(m->mtx_saveintr); 483 } 484 break; 485 case MTX_SPIN | MTX_TOPHALF: 486 if (m->mtx_recurse != 0) { 487 m->mtx_recurse--; 488 return; 489 } 490 MPASS(mtx_owned(m)); 491 _release_lock_quick(m); 492 break; 493 default: 494 panic("mtx_exit_hard: unsupported type 0x%x\n", type); 495 } 496} 497 498#define MV_DESTROY 0 /* validate before destory */ 499#define MV_INIT 1 /* validate before init */ 500 501#ifdef MUTEX_DEBUG 502 503int mtx_validate __P((struct mtx *, int)); 504 505int 506mtx_validate(struct mtx *m, int when) 507{ 508 struct mtx *mp; 509 int i; 510 int retval = 0; 511 512 if (m == &all_mtx || cold) 513 return 0; 514 515 mtx_enter(&all_mtx, MTX_DEF); 516/* 517 * XXX - When kernacc() is fixed on the alpha to handle K0_SEG memory properly 518 * we can re-enable the kernacc() checks. 519 */ 520#ifndef __alpha__ 521 MPASS(kernacc((caddr_t)all_mtx.mtx_next, sizeof(uintptr_t), 522 VM_PROT_READ) == 1); 523#endif 524 MPASS(all_mtx.mtx_next->mtx_prev == &all_mtx); 525 for (i = 0, mp = all_mtx.mtx_next; mp != &all_mtx; mp = mp->mtx_next) { 526#ifndef __alpha__ 527 if (kernacc((caddr_t)mp->mtx_next, sizeof(uintptr_t), 528 VM_PROT_READ) != 1) { 529 panic("mtx_validate: mp=%p mp->mtx_next=%p", 530 mp, mp->mtx_next); 531 } 532#endif 533 i++; 534 if (i > mtx_cur_cnt) { 535 panic("mtx_validate: too many in chain, known=%d\n", 536 mtx_cur_cnt); 537 } 538 } 539 MPASS(i == mtx_cur_cnt); 540 switch (when) { 541 case MV_DESTROY: 542 for (mp = all_mtx.mtx_next; mp != &all_mtx; mp = mp->mtx_next) 543 if (mp == m) 544 break; 545 MPASS(mp == m); 546 break; 547 case MV_INIT: 548 for (mp = all_mtx.mtx_next; mp != &all_mtx; mp = mp->mtx_next) 549 if (mp == m) { 550 /* 551 * Not good. This mutex already exists. 552 */ 553 printf("re-initing existing mutex %s\n", 554 m->mtx_description); 555 MPASS(m->mtx_lock == MTX_UNOWNED); 556 retval = 1; 557 } 558 } 559 mtx_exit(&all_mtx, MTX_DEF); 560 return (retval); 561} 562#endif 563 564void 565mtx_init(struct mtx *m, const char *t, int flag) 566{ 567#ifdef MUTEX_DEBUG 568 struct mtx_debug *debug; 569#endif 570 571 CTR2(KTR_LOCK, "mtx_init 0x%p (%s)", m, t); 572#ifdef MUTEX_DEBUG 573 if (mtx_validate(m, MV_INIT)) /* diagnostic and error correction */ 574 return; 575 if (flag & MTX_COLD) 576 debug = m->mtx_debug; 577 else 578 debug = NULL; 579 if (debug == NULL) { 580#ifdef DIAGNOSTIC 581 if(cold && bootverbose) 582 printf("malloc'ing mtx_debug while cold for %s\n", t); 583#endif 584 585 /* XXX - should not use DEVBUF */ 586 debug = malloc(sizeof(struct mtx_debug), M_DEVBUF, M_NOWAIT); 587 MPASS(debug != NULL); 588 bzero(debug, sizeof(struct mtx_debug)); 589 } 590#endif 591 bzero((void *)m, sizeof *m); 592 TAILQ_INIT(&m->mtx_blocked); 593#ifdef MUTEX_DEBUG 594 m->mtx_debug = debug; 595#endif 596 m->mtx_description = t; 597 m->mtx_lock = MTX_UNOWNED; 598 /* Put on all mutex queue */ 599 mtx_enter(&all_mtx, MTX_DEF); 600 m->mtx_next = &all_mtx; 601 m->mtx_prev = all_mtx.mtx_prev; 602 m->mtx_prev->mtx_next = m; 603 all_mtx.mtx_prev = m; 604 if (++mtx_cur_cnt > mtx_max_cnt) 605 mtx_max_cnt = mtx_cur_cnt; 606 mtx_exit(&all_mtx, MTX_DEF); 607 witness_init(m, flag); 608} 609 610void 611mtx_destroy(struct mtx *m) 612{ 613 614 CTR2(KTR_LOCK, "mtx_destroy 0x%p (%s)", m, m->mtx_description); 615#ifdef MUTEX_DEBUG 616 if (m->mtx_next == NULL) 617 panic("mtx_destroy: %p (%s) already destroyed", 618 m, m->mtx_description); 619 620 if (!mtx_owned(m)) { 621 MPASS(m->mtx_lock == MTX_UNOWNED); 622 } else { 623 MPASS((m->mtx_lock & (MTX_RECURSE|MTX_CONTESTED)) == 0); 624 } 625 mtx_validate(m, MV_DESTROY); /* diagnostic */ 626#endif 627 628#ifdef WITNESS 629 if (m->mtx_witness) 630 witness_destroy(m); 631#endif /* WITNESS */ 632 633 /* Remove from the all mutex queue */ 634 mtx_enter(&all_mtx, MTX_DEF); 635 m->mtx_next->mtx_prev = m->mtx_prev; 636 m->mtx_prev->mtx_next = m->mtx_next; 637#ifdef MUTEX_DEBUG 638 m->mtx_next = m->mtx_prev = NULL; 639 free(m->mtx_debug, M_DEVBUF); 640 m->mtx_debug = NULL; 641#endif 642 mtx_cur_cnt--; 643 mtx_exit(&all_mtx, MTX_DEF); 644} 645 646/* 647 * The non-inlined versions of the mtx_*() functions are always built (above), 648 * but the witness code depends on the MUTEX_DEBUG and WITNESS kernel options 649 * being specified. 650 */ 651#if (defined(MUTEX_DEBUG) && defined(WITNESS)) 652 653#define WITNESS_COUNT 200 654#define WITNESS_NCHILDREN 2 655 656#ifndef SMP 657extern int witness_spin_check; 658#endif 659 660int witness_watch = 1; 661 662struct witness { 663 struct witness *w_next; 664 const char *w_description; 665 const char *w_file; 666 int w_line; 667 struct witness *w_morechildren; 668 u_char w_childcnt; 669 u_char w_Giant_squawked:1; 670 u_char w_other_squawked:1; 671 u_char w_same_squawked:1; 672 u_char w_sleep:1; 673 u_char w_spin:1; /* this is a spin mutex */ 674 u_int w_level; 675 struct witness *w_children[WITNESS_NCHILDREN]; 676}; 677 678struct witness_blessed { 679 char *b_lock1; 680 char *b_lock2; 681}; 682 683#ifdef KDEBUG 684/* 685 * When WITNESS_KDEBUG is set to 1, it will cause the system to 686 * drop into kdebug() when: 687 * - a lock heirarchy violation occurs 688 * - locks are held when going to sleep. 689 */ 690#ifndef WITNESS_KDEBUG 691#define WITNESS_KDEBUG 0 692#endif 693int witness_kdebug = WITNESS_KDEBUG; 694#endif /* KDEBUG */ 695 696#ifndef WITNESS_SKIPSPIN 697#define WITNESS_SKIPSPIN 0 698#endif 699int witness_skipspin = WITNESS_SKIPSPIN; 700 701 702static struct mtx w_mtx; 703static struct witness *w_free; 704static struct witness *w_all; 705static int w_inited; 706static int witness_dead; /* fatal error, probably no memory */ 707 708static struct witness w_data[WITNESS_COUNT]; 709 710static struct witness *enroll __P((const char *description, int flag)); 711static int itismychild __P((struct witness *parent, struct witness *child)); 712static void removechild __P((struct witness *parent, struct witness *child)); 713static int isitmychild __P((struct witness *parent, struct witness *child)); 714static int isitmydescendant __P((struct witness *parent, struct witness *child)); 715static int dup_ok __P((struct witness *)); 716static int blessed __P((struct witness *, struct witness *)); 717static void witness_displaydescendants 718 __P((void(*)(const char *fmt, ...), struct witness *)); 719static void witness_leveldescendents __P((struct witness *parent, int level)); 720static void witness_levelall __P((void)); 721static struct witness * witness_get __P((void)); 722static void witness_free __P((struct witness *m)); 723 724 725static char *ignore_list[] = { 726 "witness lock", 727 "Kdebug", /* breaks rules and may or may not work */ 728 "Page Alias", /* sparc only, witness lock won't block intr */ 729 NULL 730}; 731 732static char *spin_order_list[] = { 733 "sched lock", 734 "log mtx", 735 "zslock", /* sparc only above log, this one is a real hack */ 736 "time lock", /* above callout */ 737 "callout mtx", /* above wayout */ 738 /* 739 * leaf locks 740 */ 741 "wayout mtx", 742 "kernel_pmap", /* sparc only, logically equal "pmap" below */ 743 "pmap", /* sparc only */ 744 NULL 745}; 746 747static char *order_list[] = { 748 "tcb", "inp", "so_snd", "so_rcv", "Giant lock", NULL, 749 "udb", "inp", NULL, 750 "unp head", "unp", "so_snd", NULL, 751 "de0", "Giant lock", NULL, 752 "ifnet", "Giant lock", NULL, 753 "fifo", "so_snd", NULL, 754 "hme0", "Giant lock", NULL, 755 "esp0", "Giant lock", NULL, 756 "hfa0", "Giant lock", NULL, 757 "so_rcv", "atm_global", NULL, 758 "so_snd", "atm_global", NULL, 759 "NFS", "Giant lock", NULL, 760 NULL 761}; 762 763static char *dup_list[] = { 764 "inp", 765 "process group", 766 "session", 767 "unp", 768 "rtentry", 769 "rawcb", 770 NULL 771}; 772 773static char *sleep_list[] = { 774 "Giant lock", 775 NULL 776}; 777 778/* 779 * Pairs of locks which have been blessed 780 * Don't complain about order problems with blessed locks 781 */ 782static struct witness_blessed blessed_list[] = { 783}; 784static int blessed_count = sizeof(blessed_list) / sizeof(struct witness_blessed); 785 786void 787witness_init(struct mtx *m, int flag) 788{ 789 m->mtx_witness = enroll(m->mtx_description, flag); 790} 791 792void 793witness_destroy(struct mtx *m) 794{ 795 struct mtx *m1; 796 struct proc *p; 797 p = CURPROC; 798 for ((m1 = LIST_FIRST(&p->p_heldmtx)); m1 != NULL; 799 m1 = LIST_NEXT(m1, mtx_held)) { 800 if (m1 == m) { 801 LIST_REMOVE(m, mtx_held); 802 break; 803 } 804 } 805 return; 806 807} 808 809void 810witness_enter(struct mtx *m, int flags, const char *file, int line) 811{ 812 struct witness *w, *w1; 813 struct mtx *m1; 814 struct proc *p; 815 int i; 816#ifdef KDEBUG 817 int go_into_kdebug = 0; 818#endif /* KDEBUG */ 819 820 w = m->mtx_witness; 821 p = CURPROC; 822 823 if (flags & MTX_SPIN) { 824 if (!w->w_spin) 825 panic("mutex_enter: MTX_SPIN on MTX_DEF mutex %s @" 826 " %s:%d", m->mtx_description, file, line); 827 if (m->mtx_recurse != 0) 828 return; 829 mtx_enter(&w_mtx, MTX_SPIN); 830 i = witness_spin_check; 831 if (i != 0 && w->w_level < i) { 832 mtx_exit(&w_mtx, MTX_SPIN); 833 panic("mutex_enter(%s:%x, MTX_SPIN) out of order @" 834 " %s:%d already holding %s:%x", 835 m->mtx_description, w->w_level, file, line, 836 spin_order_list[ffs(i)-1], i); 837 } 838 PCPU_SET(witness_spin_check, i | w->w_level); 839 mtx_exit(&w_mtx, MTX_SPIN); 840 return; 841 } 842 if (w->w_spin) 843 panic("mutex_enter: MTX_DEF on MTX_SPIN mutex %s @ %s:%d", 844 m->mtx_description, file, line); 845 846 if (m->mtx_recurse != 0) 847 return; 848 if (witness_dead) 849 goto out; 850 if (cold) 851 goto out; 852 853 if (!mtx_legal2block()) 854 panic("blockable mtx_enter() of %s when not legal @ %s:%d", 855 m->mtx_description, file, line); 856 /* 857 * Is this the first mutex acquired 858 */ 859 if ((m1 = LIST_FIRST(&p->p_heldmtx)) == NULL) 860 goto out; 861 862 if ((w1 = m1->mtx_witness) == w) { 863 if (w->w_same_squawked || dup_ok(w)) 864 goto out; 865 w->w_same_squawked = 1; 866 printf("acquring duplicate lock of same type: \"%s\"\n", 867 m->mtx_description); 868 printf(" 1st @ %s:%d\n", w->w_file, w->w_line); 869 printf(" 2nd @ %s:%d\n", file, line); 870#ifdef KDEBUG 871 go_into_kdebug = 1; 872#endif /* KDEBUG */ 873 goto out; 874 } 875 MPASS(!mtx_owned(&w_mtx)); 876 mtx_enter(&w_mtx, MTX_SPIN); 877 /* 878 * If we have a known higher number just say ok 879 */ 880 if (witness_watch > 1 && w->w_level > w1->w_level) { 881 mtx_exit(&w_mtx, MTX_SPIN); 882 goto out; 883 } 884 if (isitmydescendant(m1->mtx_witness, w)) { 885 mtx_exit(&w_mtx, MTX_SPIN); 886 goto out; 887 } 888 for (i = 0; m1 != NULL; m1 = LIST_NEXT(m1, mtx_held), i++) { 889 890 MPASS(i < 200); 891 w1 = m1->mtx_witness; 892 if (isitmydescendant(w, w1)) { 893 mtx_exit(&w_mtx, MTX_SPIN); 894 if (blessed(w, w1)) 895 goto out; 896 if (m1 == &Giant) { 897 if (w1->w_Giant_squawked) 898 goto out; 899 else 900 w1->w_Giant_squawked = 1; 901 } else { 902 if (w1->w_other_squawked) 903 goto out; 904 else 905 w1->w_other_squawked = 1; 906 } 907 printf("lock order reversal\n"); 908 printf(" 1st %s last acquired @ %s:%d\n", 909 w->w_description, w->w_file, w->w_line); 910 printf(" 2nd %p %s @ %s:%d\n", 911 m1, w1->w_description, w1->w_file, w1->w_line); 912 printf(" 3rd %p %s @ %s:%d\n", 913 m, w->w_description, file, line); 914#ifdef KDEBUG 915 go_into_kdebug = 1; 916#endif /* KDEBUG */ 917 goto out; 918 } 919 } 920 m1 = LIST_FIRST(&p->p_heldmtx); 921 if (!itismychild(m1->mtx_witness, w)) 922 mtx_exit(&w_mtx, MTX_SPIN); 923 924out: 925#ifdef KDEBUG 926 if (witness_kdebug && go_into_kdebug) 927 kdebug(); 928#endif /* KDEBUG */ 929 w->w_file = file; 930 w->w_line = line; 931 m->mtx_line = line; 932 m->mtx_file = file; 933 934 /* 935 * If this pays off it likely means that a mutex being witnessed 936 * is acquired in hardclock. Put it in the ignore list. It is 937 * likely not the mutex this assert fails on. 938 */ 939 MPASS(m->mtx_held.le_prev == NULL); 940 LIST_INSERT_HEAD(&p->p_heldmtx, (struct mtx*)m, mtx_held); 941} 942 943void 944witness_exit(struct mtx *m, int flags, const char *file, int line) 945{ 946 struct witness *w; 947 948 w = m->mtx_witness; 949 950 if (flags & MTX_SPIN) { 951 if (!w->w_spin) 952 panic("mutex_exit: MTX_SPIN on MTX_DEF mutex %s @" 953 " %s:%d", m->mtx_description, file, line); 954 if (m->mtx_recurse != 0) 955 return; 956 mtx_enter(&w_mtx, MTX_SPIN); 957 PCPU_SET(witness_spin_check, witness_spin_check & ~w->w_level); 958 mtx_exit(&w_mtx, MTX_SPIN); 959 return; 960 } 961 if (w->w_spin) 962 panic("mutex_exit: MTX_DEF on MTX_SPIN mutex %s @ %s:%d", 963 m->mtx_description, file, line); 964 965 if (m->mtx_recurse != 0) 966 return; 967 968 if ((flags & MTX_NOSWITCH) == 0 && !mtx_legal2block() && !cold) 969 panic("switchable mtx_exit() of %s when not legal @ %s:%d", 970 m->mtx_description, file, line); 971 LIST_REMOVE(m, mtx_held); 972 m->mtx_held.le_prev = NULL; 973} 974 975void 976witness_try_enter(struct mtx *m, int flags, const char *file, int line) 977{ 978 struct proc *p; 979 struct witness *w = m->mtx_witness; 980 981 if (flags & MTX_SPIN) { 982 if (!w->w_spin) 983 panic("mutex_try_enter: " 984 "MTX_SPIN on MTX_DEF mutex %s @ %s:%d", 985 m->mtx_description, file, line); 986 if (m->mtx_recurse != 0) 987 return; 988 mtx_enter(&w_mtx, MTX_SPIN); 989 PCPU_SET(witness_spin_check, witness_spin_check | w->w_level); 990 mtx_exit(&w_mtx, MTX_SPIN); 991 return; 992 } 993 994 if (w->w_spin) 995 panic("mutex_try_enter: MTX_DEF on MTX_SPIN mutex %s @ %s:%d", 996 m->mtx_description, file, line); 997 998 if (m->mtx_recurse != 0) 999 return; 1000 1001 w->w_file = file; 1002 w->w_line = line; 1003 m->mtx_line = line; 1004 m->mtx_file = file; 1005 p = CURPROC; 1006 MPASS(m->mtx_held.le_prev == NULL); 1007 LIST_INSERT_HEAD(&p->p_heldmtx, (struct mtx*)m, mtx_held); 1008} 1009 1010void 1011witness_display(void(*prnt)(const char *fmt, ...)) 1012{ 1013 struct witness *w, *w1; 1014 1015 witness_levelall(); 1016 1017 for (w = w_all; w; w = w->w_next) { 1018 if (w->w_file == NULL) 1019 continue; 1020 for (w1 = w_all; w1; w1 = w1->w_next) { 1021 if (isitmychild(w1, w)) 1022 break; 1023 } 1024 if (w1 != NULL) 1025 continue; 1026 /* 1027 * This lock has no anscestors, display its descendants. 1028 */ 1029 witness_displaydescendants(prnt, w); 1030 } 1031 prnt("\nMutex which were never acquired\n"); 1032 for (w = w_all; w; w = w->w_next) { 1033 if (w->w_file != NULL) 1034 continue; 1035 prnt("%s\n", w->w_description); 1036 } 1037} 1038 1039int 1040witness_sleep(int check_only, struct mtx *mtx, const char *file, int line) 1041{ 1042 struct mtx *m; 1043 struct proc *p; 1044 char **sleep; 1045 int n = 0; 1046 1047 p = CURPROC; 1048 for ((m = LIST_FIRST(&p->p_heldmtx)); m != NULL; 1049 m = LIST_NEXT(m, mtx_held)) { 1050 if (m == mtx) 1051 continue; 1052 for (sleep = sleep_list; *sleep!= NULL; sleep++) 1053 if (strcmp(m->mtx_description, *sleep) == 0) 1054 goto next; 1055 printf("%s:%d: %s with \"%s\" locked from %s:%d\n", 1056 file, line, check_only ? "could sleep" : "sleeping", 1057 m->mtx_description, 1058 m->mtx_witness->w_file, m->mtx_witness->w_line); 1059 n++; 1060 next: 1061 } 1062#ifdef KDEBUG 1063 if (witness_kdebug && n) 1064 kdebug(); 1065#endif /* KDEBUG */ 1066 return (n); 1067} 1068 1069static struct witness * 1070enroll(const char *description, int flag) 1071{ 1072 int i; 1073 struct witness *w, *w1; 1074 char **ignore; 1075 char **order; 1076 1077 if (!witness_watch) 1078 return (NULL); 1079 for (ignore = ignore_list; *ignore != NULL; ignore++) 1080 if (strcmp(description, *ignore) == 0) 1081 return (NULL); 1082 1083 if (w_inited == 0) { 1084 mtx_init(&w_mtx, "witness lock", MTX_DEF); 1085 for (i = 0; i < WITNESS_COUNT; i++) { 1086 w = &w_data[i]; 1087 witness_free(w); 1088 } 1089 w_inited = 1; 1090 for (order = order_list; *order != NULL; order++) { 1091 w = enroll(*order, MTX_DEF); 1092 w->w_file = "order list"; 1093 for (order++; *order != NULL; order++) { 1094 w1 = enroll(*order, MTX_DEF); 1095 w1->w_file = "order list"; 1096 itismychild(w, w1); 1097 w = w1; 1098 } 1099 } 1100 } 1101 if ((flag & MTX_SPIN) && witness_skipspin) 1102 return (NULL); 1103 mtx_enter(&w_mtx, MTX_SPIN); 1104 for (w = w_all; w; w = w->w_next) { 1105 if (strcmp(description, w->w_description) == 0) { 1106 mtx_exit(&w_mtx, MTX_SPIN); 1107 return (w); 1108 } 1109 } 1110 if ((w = witness_get()) == NULL) 1111 return (NULL); 1112 w->w_next = w_all; 1113 w_all = w; 1114 w->w_description = description; 1115 mtx_exit(&w_mtx, MTX_SPIN); 1116 if (flag & MTX_SPIN) { 1117 w->w_spin = 1; 1118 1119 i = 1; 1120 for (order = spin_order_list; *order != NULL; order++) { 1121 if (strcmp(description, *order) == 0) 1122 break; 1123 i <<= 1; 1124 } 1125 if (*order == NULL) 1126 panic("spin lock %s not in order list", description); 1127 w->w_level = i; 1128 } 1129 return (w); 1130} 1131 1132static int 1133itismychild(struct witness *parent, struct witness *child) 1134{ 1135 static int recursed; 1136 1137 /* 1138 * Insert "child" after "parent" 1139 */ 1140 while (parent->w_morechildren) 1141 parent = parent->w_morechildren; 1142 1143 if (parent->w_childcnt == WITNESS_NCHILDREN) { 1144 if ((parent->w_morechildren = witness_get()) == NULL) 1145 return (1); 1146 parent = parent->w_morechildren; 1147 } 1148 MPASS(child != NULL); 1149 parent->w_children[parent->w_childcnt++] = child; 1150 /* 1151 * now prune whole tree 1152 */ 1153 if (recursed) 1154 return (0); 1155 recursed = 1; 1156 for (child = w_all; child != NULL; child = child->w_next) { 1157 for (parent = w_all; parent != NULL; 1158 parent = parent->w_next) { 1159 if (!isitmychild(parent, child)) 1160 continue; 1161 removechild(parent, child); 1162 if (isitmydescendant(parent, child)) 1163 continue; 1164 itismychild(parent, child); 1165 } 1166 } 1167 recursed = 0; 1168 witness_levelall(); 1169 return (0); 1170} 1171 1172static void 1173removechild(struct witness *parent, struct witness *child) 1174{ 1175 struct witness *w, *w1; 1176 int i; 1177 1178 for (w = parent; w != NULL; w = w->w_morechildren) 1179 for (i = 0; i < w->w_childcnt; i++) 1180 if (w->w_children[i] == child) 1181 goto found; 1182 return; 1183found: 1184 for (w1 = w; w1->w_morechildren != NULL; w1 = w1->w_morechildren) 1185 continue; 1186 w->w_children[i] = w1->w_children[--w1->w_childcnt]; 1187 MPASS(w->w_children[i] != NULL); 1188 1189 if (w1->w_childcnt != 0) 1190 return; 1191 1192 if (w1 == parent) 1193 return; 1194 for (w = parent; w->w_morechildren != w1; w = w->w_morechildren) 1195 continue; 1196 w->w_morechildren = 0; 1197 witness_free(w1); 1198} 1199 1200static int 1201isitmychild(struct witness *parent, struct witness *child) 1202{ 1203 struct witness *w; 1204 int i; 1205 1206 for (w = parent; w != NULL; w = w->w_morechildren) { 1207 for (i = 0; i < w->w_childcnt; i++) { 1208 if (w->w_children[i] == child) 1209 return (1); 1210 } 1211 } 1212 return (0); 1213} 1214 1215static int 1216isitmydescendant(struct witness *parent, struct witness *child) 1217{ 1218 struct witness *w; 1219 int i; 1220 int j; 1221 1222 for (j = 0, w = parent; w != NULL; w = w->w_morechildren, j++) { 1223 MPASS(j < 1000); 1224 for (i = 0; i < w->w_childcnt; i++) { 1225 if (w->w_children[i] == child) 1226 return (1); 1227 } 1228 for (i = 0; i < w->w_childcnt; i++) { 1229 if (isitmydescendant(w->w_children[i], child)) 1230 return (1); 1231 } 1232 } 1233 return (0); 1234} 1235 1236void 1237witness_levelall (void) 1238{ 1239 struct witness *w, *w1; 1240 1241 for (w = w_all; w; w = w->w_next) 1242 if (!w->w_spin) 1243 w->w_level = 0; 1244 for (w = w_all; w; w = w->w_next) { 1245 if (w->w_spin) 1246 continue; 1247 for (w1 = w_all; w1; w1 = w1->w_next) { 1248 if (isitmychild(w1, w)) 1249 break; 1250 } 1251 if (w1 != NULL) 1252 continue; 1253 witness_leveldescendents(w, 0); 1254 } 1255} 1256 1257static void 1258witness_leveldescendents(struct witness *parent, int level) 1259{ 1260 int i; 1261 struct witness *w; 1262 1263 if (parent->w_level < level) 1264 parent->w_level = level; 1265 level++; 1266 for (w = parent; w != NULL; w = w->w_morechildren) 1267 for (i = 0; i < w->w_childcnt; i++) 1268 witness_leveldescendents(w->w_children[i], level); 1269} 1270 1271static void 1272witness_displaydescendants(void(*prnt)(const char *fmt, ...), 1273 struct witness *parent) 1274{ 1275 struct witness *w; 1276 int i; 1277 int level = parent->w_level; 1278 1279 prnt("%d", level); 1280 if (level < 10) 1281 prnt(" "); 1282 for (i = 0; i < level; i++) 1283 prnt(" "); 1284 prnt("%s", parent->w_description); 1285 if (parent->w_file != NULL) { 1286 prnt(" -- last acquired @ %s", parent->w_file); 1287#ifndef W_USE_WHERE 1288 prnt(":%d", parent->w_line); 1289#endif 1290 prnt("\n"); 1291 } 1292 1293 for (w = parent; w != NULL; w = w->w_morechildren) 1294 for (i = 0; i < w->w_childcnt; i++) 1295 witness_displaydescendants(prnt, w->w_children[i]); 1296 } 1297 1298static int 1299dup_ok(struct witness *w) 1300{ 1301 char **dup; 1302 1303 for (dup = dup_list; *dup!= NULL; dup++) 1304 if (strcmp(w->w_description, *dup) == 0) 1305 return (1); 1306 return (0); 1307} 1308 1309static int 1310blessed(struct witness *w1, struct witness *w2) 1311{ 1312 int i; 1313 struct witness_blessed *b; 1314 1315 for (i = 0; i < blessed_count; i++) { 1316 b = &blessed_list[i]; 1317 if (strcmp(w1->w_description, b->b_lock1) == 0) { 1318 if (strcmp(w2->w_description, b->b_lock2) == 0) 1319 return (1); 1320 continue; 1321 } 1322 if (strcmp(w1->w_description, b->b_lock2) == 0) 1323 if (strcmp(w2->w_description, b->b_lock1) == 0) 1324 return (1); 1325 } 1326 return (0); 1327} 1328 1329static struct witness * 1330witness_get() 1331{ 1332 struct witness *w; 1333 1334 if ((w = w_free) == NULL) { 1335 witness_dead = 1; 1336 mtx_exit(&w_mtx, MTX_SPIN); 1337 printf("witness exhausted\n"); 1338 return (NULL); 1339 } 1340 w_free = w->w_next; 1341 bzero(w, sizeof(*w)); 1342 return (w); 1343} 1344 1345static void 1346witness_free(struct witness *w) 1347{ 1348 w->w_next = w_free; 1349 w_free = w; 1350} 1351 1352void 1353witness_list(struct proc *p) 1354{ 1355 struct mtx *m; 1356 1357 for ((m = LIST_FIRST(&p->p_heldmtx)); m != NULL; 1358 m = LIST_NEXT(m, mtx_held)) { 1359 printf("\t\"%s\" (%p) locked at %s:%d\n", 1360 m->mtx_description, m, 1361 m->mtx_witness->w_file, m->mtx_witness->w_line); 1362 } 1363} 1364 1365void 1366witness_save(struct mtx *m, const char **filep, int *linep) 1367{ 1368 *filep = m->mtx_witness->w_file; 1369 *linep = m->mtx_witness->w_line; 1370} 1371 1372void 1373witness_restore(struct mtx *m, const char *file, int line) 1374{ 1375 m->mtx_witness->w_file = file; 1376 m->mtx_witness->w_line = line; 1377} 1378 1379#endif /* (defined(MUTEX_DEBUG) && defined(WITNESS)) */ 1380