subr_witness.c revision 71560
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 71560 2001-01-24 10:57:01Z jhb $ 31 */ 32 33/* 34 * Main Entry: witness 35 * Pronunciation: 'wit-n&s 36 * Function: noun 37 * Etymology: Middle English witnesse, from Old English witnes knowledge, 38 * testimony, witness, from 2wit 39 * Date: before 12th century 40 * 1 : attestation of a fact or event : TESTIMONY 41 * 2 : one that gives evidence; specifically : one who testifies in 42 * a cause or before a judicial tribunal 43 * 3 : one asked to be present at a transaction so as to be able to 44 * testify to its having taken place 45 * 4 : one who has personal knowledge of something 46 * 5 a : something serving as evidence or proof : SIGN 47 * b : public affirmation by word or example of usually 48 * religious faith or conviction <the heroic witness to divine 49 * life -- Pilot> 50 * 6 capitalized : a member of the Jehovah's Witnesses 51 */ 52 53#include "opt_ddb.h" 54#include "opt_witness.h" 55 56/* 57 * Cause non-inlined mtx_*() to be compiled. 58 * Must be defined early because other system headers may include mutex.h. 59 */ 60#define _KERN_MUTEX_C_ 61 62#include <sys/param.h> 63#include <sys/bus.h> 64#include <sys/kernel.h> 65#include <sys/malloc.h> 66#include <sys/proc.h> 67#include <sys/sysctl.h> 68#include <sys/systm.h> 69#include <sys/vmmeter.h> 70#include <sys/ktr.h> 71 72#include <machine/atomic.h> 73#include <machine/bus.h> 74#include <machine/clock.h> 75#include <machine/cpu.h> 76 77#include <ddb/ddb.h> 78 79#include <vm/vm.h> 80#include <vm/vm_extern.h> 81 82#include <sys/mutex.h> 83 84/* 85 * Machine independent bits of the mutex implementation 86 */ 87 88#ifdef WITNESS 89struct mtx_debug { 90 struct witness *mtxd_witness; 91 LIST_ENTRY(mtx) mtxd_held; 92 const char *mtxd_file; 93 int mtxd_line; 94}; 95 96#define mtx_held mtx_debug->mtxd_held 97#define mtx_file mtx_debug->mtxd_file 98#define mtx_line mtx_debug->mtxd_line 99#define mtx_witness mtx_debug->mtxd_witness 100#endif /* WITNESS */ 101 102/* 103 * Assembly macros 104 *------------------------------------------------------------------------------ 105 */ 106 107#define _V(x) __STRING(x) 108 109/* 110 * Default, unoptimized mutex micro-operations 111 */ 112 113#ifndef _obtain_lock 114/* Actually obtain mtx_lock */ 115#define _obtain_lock(mp, tid) \ 116 atomic_cmpset_acq_ptr(&(mp)->mtx_lock, (void *)MTX_UNOWNED, (tid)) 117#endif 118 119#ifndef _release_lock 120/* Actually release mtx_lock */ 121#define _release_lock(mp, tid) \ 122 atomic_cmpset_rel_ptr(&(mp)->mtx_lock, (tid), (void *)MTX_UNOWNED) 123#endif 124 125#ifndef _release_lock_quick 126/* Actually release mtx_lock quickly assuming that we own it */ 127#define _release_lock_quick(mp) \ 128 atomic_store_rel_ptr(&(mp)->mtx_lock, (void *)MTX_UNOWNED) 129#endif 130 131#ifndef _getlock_sleep 132/* Get a sleep lock, deal with recursion inline. */ 133#define _getlock_sleep(mp, tid, type) do { \ 134 if (!_obtain_lock(mp, tid)) { \ 135 if (((mp)->mtx_lock & MTX_FLAGMASK) != ((uintptr_t)(tid)))\ 136 mtx_enter_hard(mp, (type) & MTX_HARDOPTS, 0); \ 137 else { \ 138 atomic_set_ptr(&(mp)->mtx_lock, MTX_RECURSED); \ 139 (mp)->mtx_recurse++; \ 140 } \ 141 } \ 142} while (0) 143#endif 144 145#ifndef _getlock_spin_block 146/* Get a spin lock, handle recursion inline (as the less common case) */ 147#define _getlock_spin_block(mp, tid, type) do { \ 148 u_int _mtx_intr = save_intr(); \ 149 disable_intr(); \ 150 if (!_obtain_lock(mp, tid)) \ 151 mtx_enter_hard(mp, (type) & MTX_HARDOPTS, _mtx_intr); \ 152 else \ 153 (mp)->mtx_saveintr = _mtx_intr; \ 154} while (0) 155#endif 156 157#ifndef _getlock_norecurse 158/* 159 * Get a lock without any recursion handling. Calls the hard enter function if 160 * we can't get it inline. 161 */ 162#define _getlock_norecurse(mp, tid, type) do { \ 163 if (!_obtain_lock(mp, tid)) \ 164 mtx_enter_hard((mp), (type) & MTX_HARDOPTS, 0); \ 165} while (0) 166#endif 167 168#ifndef _exitlock_norecurse 169/* 170 * Release a sleep lock assuming we haven't recursed on it, recursion is handled 171 * in the hard function. 172 */ 173#define _exitlock_norecurse(mp, tid, type) do { \ 174 if (!_release_lock(mp, tid)) \ 175 mtx_exit_hard((mp), (type) & MTX_HARDOPTS); \ 176} while (0) 177#endif 178 179#ifndef _exitlock 180/* 181 * Release a sleep lock when its likely we recursed (the code to 182 * deal with simple recursion is inline). 183 */ 184#define _exitlock(mp, tid, type) do { \ 185 if (!_release_lock(mp, tid)) { \ 186 if ((mp)->mtx_lock & MTX_RECURSED) { \ 187 if (--((mp)->mtx_recurse) == 0) \ 188 atomic_clear_ptr(&(mp)->mtx_lock, \ 189 MTX_RECURSED); \ 190 } else { \ 191 mtx_exit_hard((mp), (type) & MTX_HARDOPTS); \ 192 } \ 193 } \ 194} while (0) 195#endif 196 197#ifndef _exitlock_spin 198/* Release a spin lock (with possible recursion). */ 199#define _exitlock_spin(mp) do { \ 200 if (!mtx_recursed((mp))) { \ 201 int _mtx_intr = (mp)->mtx_saveintr; \ 202 \ 203 _release_lock_quick(mp); \ 204 restore_intr(_mtx_intr); \ 205 } else { \ 206 (mp)->mtx_recurse--; \ 207 } \ 208} while (0) 209#endif 210 211#ifdef WITNESS 212static void witness_init(struct mtx *, int flag); 213static void witness_destroy(struct mtx *); 214static void witness_display(void(*)(const char *fmt, ...)); 215 216/* All mutexes in system (used for debug/panic) */ 217static struct mtx_debug all_mtx_debug = { NULL, {NULL, NULL}, NULL, 0 }; 218/* 219 * Set to 0 once mutexes have been fully initialized so that witness code can be 220 * safely executed. 221 */ 222static int witness_cold = 1; 223#else /* WITNESS */ 224 225/* 226 * flag++ is slezoid way of shutting up unused parameter warning 227 * in mtx_init() 228 */ 229#define witness_init(m, flag) flag++ 230#define witness_destroy(m) 231#define witness_try_enter(m, t, f, l) 232#endif /* WITNESS */ 233 234/* All mutexes in system (used for debug/panic) */ 235static struct mtx all_mtx = { MTX_UNOWNED, 0, 0, 0, "All mutexes queue head", 236 TAILQ_HEAD_INITIALIZER(all_mtx.mtx_blocked), 237 { NULL, NULL }, &all_mtx, &all_mtx, 238#ifdef WITNESS 239 &all_mtx_debug 240#else 241 NULL 242#endif 243 }; 244 245static int mtx_cur_cnt; 246static int mtx_max_cnt; 247 248static void propagate_priority(struct proc *); 249static void mtx_enter_hard(struct mtx *, int type, int saveintr); 250static void mtx_exit_hard(struct mtx *, int type); 251 252#define mtx_unowned(m) ((m)->mtx_lock == MTX_UNOWNED) 253#define mtx_owner(m) (mtx_unowned(m) ? NULL \ 254 : (struct proc *)((m)->mtx_lock & MTX_FLAGMASK)) 255 256#define RETIP(x) *(((uintptr_t *)(&x)) - 1) 257#define SET_PRIO(p, pri) (p)->p_priority = (pri) 258 259static void 260propagate_priority(struct proc *p) 261{ 262 int pri = p->p_priority; 263 struct mtx *m = p->p_blocked; 264 265 mtx_assert(&sched_lock, MA_OWNED); 266 for (;;) { 267 struct proc *p1; 268 269 p = mtx_owner(m); 270 271 if (p == NULL) { 272 /* 273 * This really isn't quite right. Really 274 * ought to bump priority of process that 275 * next acquires the mutex. 276 */ 277 MPASS(m->mtx_lock == MTX_CONTESTED); 278 return; 279 } 280 MPASS(p->p_magic == P_MAGIC); 281 KASSERT(p->p_stat != SSLEEP, ("sleeping process owns a mutex")); 282 if (p->p_priority <= pri) 283 return; 284 285 /* 286 * Bump this process' priority. 287 */ 288 SET_PRIO(p, pri); 289 290 /* 291 * If lock holder is actually running, just bump priority. 292 */ 293#ifdef SMP 294 /* 295 * For SMP, we can check the p_oncpu field to see if we are 296 * running. 297 */ 298 if (p->p_oncpu != 0xff) { 299 MPASS(p->p_stat == SRUN || p->p_stat == SZOMB); 300 return; 301 } 302#else 303 /* 304 * For UP, we check to see if p is curproc (this shouldn't 305 * ever happen however as it would mean we are in a deadlock.) 306 */ 307 if (p == curproc) { 308 panic("Deadlock detected"); 309 return; 310 } 311#endif 312 /* 313 * If on run queue move to new run queue, and 314 * quit. 315 */ 316 if (p->p_stat == SRUN) { 317 printf("XXX: moving process %d(%s) to a new run queue\n", 318 p->p_pid, p->p_comm); 319 MPASS(p->p_blocked == NULL); 320 remrunqueue(p); 321 setrunqueue(p); 322 return; 323 } 324 325 /* 326 * If we aren't blocked on a mutex, we should be. 327 */ 328 KASSERT(p->p_stat == SMTX, ( 329 "process %d(%s):%d holds %s but isn't blocked on a mutex\n", 330 p->p_pid, p->p_comm, p->p_stat, 331 m->mtx_description)); 332 333 /* 334 * Pick up the mutex that p is blocked on. 335 */ 336 m = p->p_blocked; 337 MPASS(m != NULL); 338 339 printf("XXX: process %d(%s) is blocked on %s\n", p->p_pid, 340 p->p_comm, m->mtx_description); 341 /* 342 * Check if the proc needs to be moved up on 343 * the blocked chain 344 */ 345 if (p == TAILQ_FIRST(&m->mtx_blocked)) { 346 printf("XXX: process at head of run queue\n"); 347 continue; 348 } 349 p1 = TAILQ_PREV(p, rq, p_procq); 350 if (p1->p_priority <= pri) { 351 printf( 352 "XXX: previous process %d(%s) has higher priority\n", 353 p->p_pid, p->p_comm); 354 continue; 355 } 356 357 /* 358 * Remove proc from blocked chain and determine where 359 * it should be moved up to. Since we know that p1 has 360 * a lower priority than p, we know that at least one 361 * process in the chain has a lower priority and that 362 * p1 will thus not be NULL after the loop. 363 */ 364 TAILQ_REMOVE(&m->mtx_blocked, p, p_procq); 365 TAILQ_FOREACH(p1, &m->mtx_blocked, p_procq) { 366 MPASS(p1->p_magic == P_MAGIC); 367 if (p1->p_priority > pri) 368 break; 369 } 370 MPASS(p1 != NULL); 371 TAILQ_INSERT_BEFORE(p1, p, p_procq); 372 CTR4(KTR_LOCK, 373 "propagate_priority: p %p moved before %p on [%p] %s", 374 p, p1, m, m->mtx_description); 375 } 376} 377 378/* 379 * Get lock 'm', the macro handles the easy (and most common cases) and leaves 380 * the slow stuff to the mtx_enter_hard() function. 381 * 382 * Note: since type is usually a constant much of this code is optimized out. 383 */ 384void 385_mtx_enter(struct mtx *mtxp, int type, const char *file, int line) 386{ 387 struct mtx *mpp = mtxp; 388 389 /* bits only valid on mtx_exit() */ 390 MPASS4(((type) & (MTX_NORECURSE | MTX_NOSWITCH)) == 0, 391 STR_mtx_bad_type, file, line); 392 393 if ((type) & MTX_SPIN) { 394 /* 395 * Easy cases of spin locks: 396 * 397 * 1) We already own the lock and will simply recurse on it (if 398 * RLIKELY) 399 * 400 * 2) The lock is free, we just get it 401 */ 402 if ((type) & MTX_RLIKELY) { 403 /* 404 * Check for recursion, if we already have this 405 * lock we just bump the recursion count. 406 */ 407 if (mpp->mtx_lock == (uintptr_t)CURTHD) { 408 mpp->mtx_recurse++; 409 goto done; 410 } 411 } 412 413 if (((type) & MTX_TOPHALF) == 0) { 414 /* 415 * If an interrupt thread uses this we must block 416 * interrupts here. 417 */ 418 if ((type) & MTX_FIRST) { 419 ASS_IEN; 420 disable_intr(); 421 _getlock_norecurse(mpp, CURTHD, 422 (type) & MTX_HARDOPTS); 423 } else { 424 _getlock_spin_block(mpp, CURTHD, 425 (type) & MTX_HARDOPTS); 426 } 427 } else 428 _getlock_norecurse(mpp, CURTHD, (type) & MTX_HARDOPTS); 429 } else { 430 /* Sleep locks */ 431 if ((type) & MTX_RLIKELY) 432 _getlock_sleep(mpp, CURTHD, (type) & MTX_HARDOPTS); 433 else 434 _getlock_norecurse(mpp, CURTHD, (type) & MTX_HARDOPTS); 435 } 436done: 437 WITNESS_ENTER(mpp, type, file, line); 438 if (((type) & MTX_QUIET) == 0) 439 CTR5(KTR_LOCK, STR_mtx_enter_fmt, 440 mpp->mtx_description, mpp, mpp->mtx_recurse, file, line); 441 442} 443 444/* 445 * Attempt to get MTX_DEF lock, return non-zero if lock acquired. 446 * 447 * XXX DOES NOT HANDLE RECURSION 448 */ 449int 450_mtx_try_enter(struct mtx *mtxp, int type, const char *file, int line) 451{ 452 struct mtx *const mpp = mtxp; 453 int rval; 454 455 rval = _obtain_lock(mpp, CURTHD); 456#ifdef WITNESS 457 if (rval && mpp->mtx_witness != NULL) { 458 MPASS(mpp->mtx_recurse == 0); 459 witness_try_enter(mpp, type, file, line); 460 } 461#endif /* WITNESS */ 462 if (((type) & MTX_QUIET) == 0) 463 CTR5(KTR_LOCK, STR_mtx_try_enter_fmt, 464 mpp->mtx_description, mpp, rval, file, line); 465 466 return rval; 467} 468 469/* 470 * Release lock m. 471 */ 472void 473_mtx_exit(struct mtx *mtxp, int type, const char *file, int line) 474{ 475 struct mtx *const mpp = mtxp; 476 477 MPASS4(mtx_owned(mpp), STR_mtx_owned, file, line); 478 WITNESS_EXIT(mpp, type, file, line); 479 if (((type) & MTX_QUIET) == 0) 480 CTR5(KTR_LOCK, STR_mtx_exit_fmt, 481 mpp->mtx_description, mpp, mpp->mtx_recurse, file, line); 482 if ((type) & MTX_SPIN) { 483 if ((type) & MTX_NORECURSE) { 484 int mtx_intr = mpp->mtx_saveintr; 485 486 MPASS4(mpp->mtx_recurse == 0, STR_mtx_recurse, 487 file, line); 488 _release_lock_quick(mpp); 489 if (((type) & MTX_TOPHALF) == 0) { 490 if ((type) & MTX_FIRST) { 491 ASS_IDIS; 492 enable_intr(); 493 } else 494 restore_intr(mtx_intr); 495 } 496 } else { 497 if (((type & MTX_TOPHALF) == 0) && 498 (type & MTX_FIRST)) { 499 ASS_IDIS; 500 ASS_SIEN(mpp); 501 } 502 _exitlock_spin(mpp); 503 } 504 } else { 505 /* Handle sleep locks */ 506 if ((type) & MTX_RLIKELY) 507 _exitlock(mpp, CURTHD, (type) & MTX_HARDOPTS); 508 else { 509 _exitlock_norecurse(mpp, CURTHD, 510 (type) & MTX_HARDOPTS); 511 } 512 } 513} 514 515void 516mtx_enter_hard(struct mtx *m, int type, int saveintr) 517{ 518 struct proc *p = CURPROC; 519 520 KASSERT(p != NULL, ("curproc is NULL in mutex")); 521 522 switch (type) { 523 case MTX_DEF: 524 if ((m->mtx_lock & MTX_FLAGMASK) == (uintptr_t)p) { 525 m->mtx_recurse++; 526 atomic_set_ptr(&m->mtx_lock, MTX_RECURSED); 527 if ((type & MTX_QUIET) == 0) 528 CTR1(KTR_LOCK, "mtx_enter: %p recurse", m); 529 return; 530 } 531 if ((type & MTX_QUIET) == 0) 532 CTR3(KTR_LOCK, 533 "mtx_enter: %p contested (lock=%p) [%p]", 534 m, (void *)m->mtx_lock, (void *)RETIP(m)); 535 536 /* 537 * Save our priority. Even though p_nativepri is protected 538 * by sched_lock, we don't obtain it here as it can be 539 * expensive. Since this is the only place p_nativepri is 540 * set, and since two CPUs will not be executing the same 541 * process concurrently, we know that no other CPU is going 542 * to be messing with this. Also, p_nativepri is only read 543 * when we are blocked on a mutex, so that can't be happening 544 * right now either. 545 */ 546 p->p_nativepri = p->p_priority; 547 while (!_obtain_lock(m, p)) { 548 uintptr_t v; 549 struct proc *p1; 550 551 mtx_enter(&sched_lock, MTX_SPIN | MTX_RLIKELY); 552 /* 553 * check if the lock has been released while 554 * waiting for the schedlock. 555 */ 556 if ((v = m->mtx_lock) == MTX_UNOWNED) { 557 mtx_exit(&sched_lock, MTX_SPIN); 558 continue; 559 } 560 /* 561 * The mutex was marked contested on release. This 562 * means that there are processes blocked on it. 563 */ 564 if (v == MTX_CONTESTED) { 565 p1 = TAILQ_FIRST(&m->mtx_blocked); 566 KASSERT(p1 != NULL, ("contested mutex has no contesters")); 567 KASSERT(p != NULL, ("curproc is NULL for contested mutex")); 568 m->mtx_lock = (uintptr_t)p | MTX_CONTESTED; 569 if (p1->p_priority < p->p_priority) { 570 SET_PRIO(p, p1->p_priority); 571 } 572 mtx_exit(&sched_lock, MTX_SPIN); 573 return; 574 } 575 /* 576 * If the mutex isn't already contested and 577 * a failure occurs setting the contested bit the 578 * mutex was either release or the 579 * state of the RECURSION bit changed. 580 */ 581 if ((v & MTX_CONTESTED) == 0 && 582 !atomic_cmpset_ptr(&m->mtx_lock, (void *)v, 583 (void *)(v | MTX_CONTESTED))) { 584 mtx_exit(&sched_lock, MTX_SPIN); 585 continue; 586 } 587 588 /* We definitely have to sleep for this lock */ 589 mtx_assert(m, MA_NOTOWNED); 590 591#ifdef notyet 592 /* 593 * If we're borrowing an interrupted thread's VM 594 * context must clean up before going to sleep. 595 */ 596 if (p->p_flag & (P_ITHD | P_SITHD)) { 597 ithd_t *it = (ithd_t *)p; 598 599 if (it->it_interrupted) { 600 if ((type & MTX_QUIET) == 0) 601 CTR2(KTR_LOCK, 602 "mtx_enter: 0x%x interrupted 0x%x", 603 it, it->it_interrupted); 604 intr_thd_fixup(it); 605 } 606 } 607#endif 608 609 /* Put us on the list of procs blocked on this mutex */ 610 if (TAILQ_EMPTY(&m->mtx_blocked)) { 611 p1 = (struct proc *)(m->mtx_lock & 612 MTX_FLAGMASK); 613 LIST_INSERT_HEAD(&p1->p_contested, m, 614 mtx_contested); 615 TAILQ_INSERT_TAIL(&m->mtx_blocked, p, p_procq); 616 } else { 617 TAILQ_FOREACH(p1, &m->mtx_blocked, p_procq) 618 if (p1->p_priority > p->p_priority) 619 break; 620 if (p1) 621 TAILQ_INSERT_BEFORE(p1, p, p_procq); 622 else 623 TAILQ_INSERT_TAIL(&m->mtx_blocked, p, 624 p_procq); 625 } 626 627 p->p_blocked = m; /* Who we're blocked on */ 628 p->p_mtxname = m->mtx_description; 629 p->p_stat = SMTX; 630#if 0 631 propagate_priority(p); 632#endif 633 if ((type & MTX_QUIET) == 0) 634 CTR3(KTR_LOCK, 635 "mtx_enter: p %p blocked on [%p] %s", 636 p, m, m->mtx_description); 637 mi_switch(); 638 if ((type & MTX_QUIET) == 0) 639 CTR3(KTR_LOCK, 640 "mtx_enter: p %p free from blocked on [%p] %s", 641 p, m, m->mtx_description); 642 mtx_exit(&sched_lock, MTX_SPIN); 643 } 644 return; 645 case MTX_SPIN: 646 case MTX_SPIN | MTX_FIRST: 647 case MTX_SPIN | MTX_TOPHALF: 648 { 649 int i = 0; 650 651 if (m->mtx_lock == (uintptr_t)p) { 652 m->mtx_recurse++; 653 return; 654 } 655 if ((type & MTX_QUIET) == 0) 656 CTR1(KTR_LOCK, "mtx_enter: %p spinning", m); 657 for (;;) { 658 if (_obtain_lock(m, p)) 659 break; 660 while (m->mtx_lock != MTX_UNOWNED) { 661 if (i++ < 1000000) 662 continue; 663 if (i++ < 6000000) 664 DELAY (1); 665#ifdef DDB 666 else if (!db_active) 667#else 668 else 669#endif 670 panic( 671 "spin lock %s held by %p for > 5 seconds", 672 m->mtx_description, 673 (void *)m->mtx_lock); 674 } 675 } 676 677#ifdef MUTEX_DEBUG 678 if (type != MTX_SPIN) 679 m->mtx_saveintr = 0xbeefface; 680 else 681#endif 682 m->mtx_saveintr = saveintr; 683 if ((type & MTX_QUIET) == 0) 684 CTR1(KTR_LOCK, "mtx_enter: %p spin done", m); 685 return; 686 } 687 } 688} 689 690void 691mtx_exit_hard(struct mtx *m, int type) 692{ 693 struct proc *p, *p1; 694 struct mtx *m1; 695 int pri; 696 697 p = CURPROC; 698 switch (type) { 699 case MTX_DEF: 700 case MTX_DEF | MTX_NOSWITCH: 701 if (mtx_recursed(m)) { 702 if (--(m->mtx_recurse) == 0) 703 atomic_clear_ptr(&m->mtx_lock, MTX_RECURSED); 704 if ((type & MTX_QUIET) == 0) 705 CTR1(KTR_LOCK, "mtx_exit: %p unrecurse", m); 706 return; 707 } 708 mtx_enter(&sched_lock, MTX_SPIN); 709 if ((type & MTX_QUIET) == 0) 710 CTR1(KTR_LOCK, "mtx_exit: %p contested", m); 711 p1 = TAILQ_FIRST(&m->mtx_blocked); 712 MPASS(p->p_magic == P_MAGIC); 713 MPASS(p1->p_magic == P_MAGIC); 714 TAILQ_REMOVE(&m->mtx_blocked, p1, p_procq); 715 if (TAILQ_EMPTY(&m->mtx_blocked)) { 716 LIST_REMOVE(m, mtx_contested); 717 _release_lock_quick(m); 718 if ((type & MTX_QUIET) == 0) 719 CTR1(KTR_LOCK, "mtx_exit: %p not held", m); 720 } else 721 atomic_store_rel_ptr(&m->mtx_lock, 722 (void *)MTX_CONTESTED); 723 pri = MAXPRI; 724 LIST_FOREACH(m1, &p->p_contested, mtx_contested) { 725 int cp = TAILQ_FIRST(&m1->mtx_blocked)->p_priority; 726 if (cp < pri) 727 pri = cp; 728 } 729 if (pri > p->p_nativepri) 730 pri = p->p_nativepri; 731 SET_PRIO(p, pri); 732 if ((type & MTX_QUIET) == 0) 733 CTR2(KTR_LOCK, 734 "mtx_exit: %p contested setrunqueue %p", m, p1); 735 p1->p_blocked = NULL; 736 p1->p_mtxname = NULL; 737 p1->p_stat = SRUN; 738 setrunqueue(p1); 739 if ((type & MTX_NOSWITCH) == 0 && p1->p_priority < pri) { 740#ifdef notyet 741 if (p->p_flag & (P_ITHD | P_SITHD)) { 742 ithd_t *it = (ithd_t *)p; 743 744 if (it->it_interrupted) { 745 if ((type & MTX_QUIET) == 0) 746 CTR2(KTR_LOCK, 747 "mtx_exit: 0x%x interruped 0x%x", 748 it, it->it_interrupted); 749 intr_thd_fixup(it); 750 } 751 } 752#endif 753 setrunqueue(p); 754 if ((type & MTX_QUIET) == 0) 755 CTR2(KTR_LOCK, 756 "mtx_exit: %p switching out lock=%p", 757 m, (void *)m->mtx_lock); 758 mi_switch(); 759 if ((type & MTX_QUIET) == 0) 760 CTR2(KTR_LOCK, 761 "mtx_exit: %p resuming lock=%p", 762 m, (void *)m->mtx_lock); 763 } 764 mtx_exit(&sched_lock, MTX_SPIN); 765 break; 766 case MTX_SPIN: 767 case MTX_SPIN | MTX_FIRST: 768 if (mtx_recursed(m)) { 769 m->mtx_recurse--; 770 return; 771 } 772 MPASS(mtx_owned(m)); 773 _release_lock_quick(m); 774 if (type & MTX_FIRST) 775 enable_intr(); /* XXX is this kosher? */ 776 else { 777 MPASS(m->mtx_saveintr != 0xbeefface); 778 restore_intr(m->mtx_saveintr); 779 } 780 break; 781 case MTX_SPIN | MTX_TOPHALF: 782 if (mtx_recursed(m)) { 783 m->mtx_recurse--; 784 return; 785 } 786 MPASS(mtx_owned(m)); 787 _release_lock_quick(m); 788 break; 789 default: 790 panic("mtx_exit_hard: unsupported type 0x%x\n", type); 791 } 792} 793 794#ifdef INVARIANTS 795void 796_mtx_assert(struct mtx *m, int what, const char *file, int line) 797{ 798 switch ((what)) { 799 case MA_OWNED: 800 case MA_OWNED | MA_RECURSED: 801 case MA_OWNED | MA_NOTRECURSED: 802 if (!mtx_owned((m))) 803 panic("mutex %s not owned at %s:%d", 804 (m)->mtx_description, file, line); 805 if (mtx_recursed((m))) { 806 if (((what) & MA_NOTRECURSED) != 0) 807 panic("mutex %s recursed at %s:%d", 808 (m)->mtx_description, file, line); 809 } else if (((what) & MA_RECURSED) != 0) { 810 panic("mutex %s unrecursed at %s:%d", 811 (m)->mtx_description, file, line); 812 } 813 break; 814 case MA_NOTOWNED: 815 if (mtx_owned((m))) 816 panic("mutex %s owned at %s:%d", 817 (m)->mtx_description, file, line); 818 break; 819 default: 820 panic("unknown mtx_assert at %s:%d", file, line); 821 } 822} 823#endif 824 825#define MV_DESTROY 0 /* validate before destory */ 826#define MV_INIT 1 /* validate before init */ 827 828#ifdef MUTEX_DEBUG 829 830int mtx_validate __P((struct mtx *, int)); 831 832int 833mtx_validate(struct mtx *m, int when) 834{ 835 struct mtx *mp; 836 int i; 837 int retval = 0; 838 839#ifdef WITNESS 840 if (witness_cold) 841 return 0; 842#endif 843 if (m == &all_mtx || cold) 844 return 0; 845 846 mtx_enter(&all_mtx, MTX_DEF); 847/* 848 * XXX - When kernacc() is fixed on the alpha to handle K0_SEG memory properly 849 * we can re-enable the kernacc() checks. 850 */ 851#ifndef __alpha__ 852 MPASS(kernacc((caddr_t)all_mtx.mtx_next, sizeof(uintptr_t), 853 VM_PROT_READ) == 1); 854#endif 855 MPASS(all_mtx.mtx_next->mtx_prev == &all_mtx); 856 for (i = 0, mp = all_mtx.mtx_next; mp != &all_mtx; mp = mp->mtx_next) { 857#ifndef __alpha__ 858 if (kernacc((caddr_t)mp->mtx_next, sizeof(uintptr_t), 859 VM_PROT_READ) != 1) { 860 panic("mtx_validate: mp=%p mp->mtx_next=%p", 861 mp, mp->mtx_next); 862 } 863#endif 864 i++; 865 if (i > mtx_cur_cnt) { 866 panic("mtx_validate: too many in chain, known=%d\n", 867 mtx_cur_cnt); 868 } 869 } 870 MPASS(i == mtx_cur_cnt); 871 switch (when) { 872 case MV_DESTROY: 873 for (mp = all_mtx.mtx_next; mp != &all_mtx; mp = mp->mtx_next) 874 if (mp == m) 875 break; 876 MPASS(mp == m); 877 break; 878 case MV_INIT: 879 for (mp = all_mtx.mtx_next; mp != &all_mtx; mp = mp->mtx_next) 880 if (mp == m) { 881 /* 882 * Not good. This mutex already exists. 883 */ 884 printf("re-initing existing mutex %s\n", 885 m->mtx_description); 886 MPASS(m->mtx_lock == MTX_UNOWNED); 887 retval = 1; 888 } 889 } 890 mtx_exit(&all_mtx, MTX_DEF); 891 return (retval); 892} 893#endif 894 895void 896mtx_init(struct mtx *m, const char *t, int flag) 897{ 898 if ((flag & MTX_QUIET) == 0) 899 CTR2(KTR_LOCK, "mtx_init %p (%s)", m, t); 900#ifdef MUTEX_DEBUG 901 if (mtx_validate(m, MV_INIT)) /* diagnostic and error correction */ 902 return; 903#endif 904 905 bzero((void *)m, sizeof *m); 906 TAILQ_INIT(&m->mtx_blocked); 907#ifdef WITNESS 908 if (!witness_cold) { 909 /* XXX - should not use DEVBUF */ 910 m->mtx_debug = malloc(sizeof(struct mtx_debug), 911 M_DEVBUF, M_NOWAIT | M_ZERO); 912 MPASS(m->mtx_debug != NULL); 913 } 914#endif 915 m->mtx_description = t; 916 917 m->mtx_flags = flag; 918 m->mtx_lock = MTX_UNOWNED; 919 /* Put on all mutex queue */ 920 mtx_enter(&all_mtx, MTX_DEF); 921 m->mtx_next = &all_mtx; 922 m->mtx_prev = all_mtx.mtx_prev; 923 m->mtx_prev->mtx_next = m; 924 all_mtx.mtx_prev = m; 925 if (++mtx_cur_cnt > mtx_max_cnt) 926 mtx_max_cnt = mtx_cur_cnt; 927 mtx_exit(&all_mtx, MTX_DEF); 928#ifdef WITNESS 929 if (!witness_cold) 930 witness_init(m, flag); 931#endif 932} 933 934void 935mtx_destroy(struct mtx *m) 936{ 937 938#ifdef WITNESS 939 KASSERT(!witness_cold, ("%s: Cannot destroy while still cold\n", 940 __FUNCTION__)); 941#endif 942 CTR2(KTR_LOCK, "mtx_destroy %p (%s)", m, m->mtx_description); 943#ifdef MUTEX_DEBUG 944 if (m->mtx_next == NULL) 945 panic("mtx_destroy: %p (%s) already destroyed", 946 m, m->mtx_description); 947 948 if (!mtx_owned(m)) { 949 MPASS(m->mtx_lock == MTX_UNOWNED); 950 } else { 951 MPASS((m->mtx_lock & (MTX_RECURSED|MTX_CONTESTED)) == 0); 952 } 953 mtx_validate(m, MV_DESTROY); /* diagnostic */ 954#endif 955 956#ifdef WITNESS 957 if (m->mtx_witness) 958 witness_destroy(m); 959#endif /* WITNESS */ 960 961 /* Remove from the all mutex queue */ 962 mtx_enter(&all_mtx, MTX_DEF); 963 m->mtx_next->mtx_prev = m->mtx_prev; 964 m->mtx_prev->mtx_next = m->mtx_next; 965#ifdef MUTEX_DEBUG 966 m->mtx_next = m->mtx_prev = NULL; 967#endif 968#ifdef WITNESS 969 free(m->mtx_debug, M_DEVBUF); 970 m->mtx_debug = NULL; 971#endif 972 mtx_cur_cnt--; 973 mtx_exit(&all_mtx, MTX_DEF); 974} 975 976/* 977 * The non-inlined versions of the mtx_*() functions are always built (above), 978 * but the witness code depends on the WITNESS kernel option being specified. 979 */ 980 981#ifdef WITNESS 982static void 983witness_fixup(void *dummy __unused) 984{ 985 struct mtx *mp; 986 987 /* 988 * We have to release Giant before initializing its witness 989 * structure so that WITNESS doesn't get confused. 990 */ 991 mtx_exit(&Giant, MTX_DEF); 992 mtx_assert(&Giant, MA_NOTOWNED); 993 mtx_enter(&all_mtx, MTX_DEF); 994 995 /* Iterate through all mutexes and finish up mutex initialization. */ 996 for (mp = all_mtx.mtx_next; mp != &all_mtx; mp = mp->mtx_next) { 997 998 /* XXX - should not use DEVBUF */ 999 mp->mtx_debug = malloc(sizeof(struct mtx_debug), 1000 M_DEVBUF, M_NOWAIT | M_ZERO); 1001 MPASS(mp->mtx_debug != NULL); 1002 1003 witness_init(mp, mp->mtx_flags); 1004 } 1005 mtx_exit(&all_mtx, MTX_DEF); 1006 1007 /* Mark the witness code as being ready for use. */ 1008 atomic_store_rel_int(&witness_cold, 0); 1009 1010 mtx_enter(&Giant, MTX_DEF); 1011} 1012SYSINIT(wtnsfxup, SI_SUB_MUTEX, SI_ORDER_FIRST, witness_fixup, NULL) 1013 1014#define WITNESS_COUNT 200 1015#define WITNESS_NCHILDREN 2 1016 1017int witness_watch = 1; 1018 1019struct witness { 1020 struct witness *w_next; 1021 const char *w_description; 1022 const char *w_file; 1023 int w_line; 1024 struct witness *w_morechildren; 1025 u_char w_childcnt; 1026 u_char w_Giant_squawked:1; 1027 u_char w_other_squawked:1; 1028 u_char w_same_squawked:1; 1029 u_char w_spin:1; /* MTX_SPIN type mutex. */ 1030 u_int w_level; 1031 struct witness *w_children[WITNESS_NCHILDREN]; 1032}; 1033 1034struct witness_blessed { 1035 char *b_lock1; 1036 char *b_lock2; 1037}; 1038 1039#ifdef DDB 1040/* 1041 * When DDB is enabled and witness_ddb is set to 1, it will cause the system to 1042 * drop into kdebug() when: 1043 * - a lock heirarchy violation occurs 1044 * - locks are held when going to sleep. 1045 */ 1046int witness_ddb; 1047#ifdef WITNESS_DDB 1048TUNABLE_INT_DECL("debug.witness_ddb", 1, witness_ddb); 1049#else 1050TUNABLE_INT_DECL("debug.witness_ddb", 0, witness_ddb); 1051#endif 1052SYSCTL_INT(_debug, OID_AUTO, witness_ddb, CTLFLAG_RW, &witness_ddb, 0, ""); 1053#endif /* DDB */ 1054 1055int witness_skipspin; 1056#ifdef WITNESS_SKIPSPIN 1057TUNABLE_INT_DECL("debug.witness_skipspin", 1, witness_skipspin); 1058#else 1059TUNABLE_INT_DECL("debug.witness_skipspin", 0, witness_skipspin); 1060#endif 1061SYSCTL_INT(_debug, OID_AUTO, witness_skipspin, CTLFLAG_RD, &witness_skipspin, 0, 1062 ""); 1063 1064static struct mtx w_mtx; 1065static struct witness *w_free; 1066static struct witness *w_all; 1067static int w_inited; 1068static int witness_dead; /* fatal error, probably no memory */ 1069 1070static struct witness w_data[WITNESS_COUNT]; 1071 1072static struct witness *enroll __P((const char *description, int flag)); 1073static int itismychild __P((struct witness *parent, struct witness *child)); 1074static void removechild __P((struct witness *parent, struct witness *child)); 1075static int isitmychild __P((struct witness *parent, struct witness *child)); 1076static int isitmydescendant __P((struct witness *parent, struct witness *child)); 1077static int dup_ok __P((struct witness *)); 1078static int blessed __P((struct witness *, struct witness *)); 1079static void witness_displaydescendants 1080 __P((void(*)(const char *fmt, ...), struct witness *)); 1081static void witness_leveldescendents __P((struct witness *parent, int level)); 1082static void witness_levelall __P((void)); 1083static struct witness * witness_get __P((void)); 1084static void witness_free __P((struct witness *m)); 1085 1086 1087static char *ignore_list[] = { 1088 "witness lock", 1089 NULL 1090}; 1091 1092static char *spin_order_list[] = { 1093 "sio", 1094 "sched lock", 1095#ifdef __i386__ 1096 "clk", 1097#endif 1098 "callout", 1099 /* 1100 * leaf locks 1101 */ 1102 NULL 1103}; 1104 1105static char *order_list[] = { 1106 "Giant", "uidinfo hash", "uidinfo struct", NULL, 1107 "Giant", "proctree", "allproc", "process lock", NULL, 1108 NULL 1109}; 1110 1111static char *dup_list[] = { 1112 NULL 1113}; 1114 1115static char *sleep_list[] = { 1116 "Giant", 1117 NULL 1118}; 1119 1120/* 1121 * Pairs of locks which have been blessed 1122 * Don't complain about order problems with blessed locks 1123 */ 1124static struct witness_blessed blessed_list[] = { 1125}; 1126static int blessed_count = sizeof(blessed_list) / sizeof(struct witness_blessed); 1127 1128static void 1129witness_init(struct mtx *m, int flag) 1130{ 1131 m->mtx_witness = enroll(m->mtx_description, flag); 1132} 1133 1134static void 1135witness_destroy(struct mtx *m) 1136{ 1137 struct mtx *m1; 1138 struct proc *p; 1139 p = CURPROC; 1140 for ((m1 = LIST_FIRST(&p->p_heldmtx)); m1 != NULL; 1141 m1 = LIST_NEXT(m1, mtx_held)) { 1142 if (m1 == m) { 1143 LIST_REMOVE(m, mtx_held); 1144 break; 1145 } 1146 } 1147 return; 1148 1149} 1150 1151static void 1152witness_display(void(*prnt)(const char *fmt, ...)) 1153{ 1154 struct witness *w, *w1; 1155 1156 KASSERT(!witness_cold, ("%s: witness_cold\n", __FUNCTION__)); 1157 witness_levelall(); 1158 1159 for (w = w_all; w; w = w->w_next) { 1160 if (w->w_file == NULL) 1161 continue; 1162 for (w1 = w_all; w1; w1 = w1->w_next) { 1163 if (isitmychild(w1, w)) 1164 break; 1165 } 1166 if (w1 != NULL) 1167 continue; 1168 /* 1169 * This lock has no anscestors, display its descendants. 1170 */ 1171 witness_displaydescendants(prnt, w); 1172 } 1173 prnt("\nMutex which were never acquired\n"); 1174 for (w = w_all; w; w = w->w_next) { 1175 if (w->w_file != NULL) 1176 continue; 1177 prnt("%s\n", w->w_description); 1178 } 1179} 1180 1181void 1182witness_enter(struct mtx *m, int flags, const char *file, int line) 1183{ 1184 struct witness *w, *w1; 1185 struct mtx *m1; 1186 struct proc *p; 1187 int i; 1188#ifdef DDB 1189 int go_into_ddb = 0; 1190#endif /* DDB */ 1191 1192 if (witness_cold || m->mtx_witness == NULL || panicstr) 1193 return; 1194 w = m->mtx_witness; 1195 p = CURPROC; 1196 1197 if (flags & MTX_SPIN) { 1198 if ((m->mtx_flags & MTX_SPIN) == 0) 1199 panic("mutex_enter: MTX_SPIN on MTX_DEF mutex %s @" 1200 " %s:%d", m->mtx_description, file, line); 1201 if (mtx_recursed(m)) { 1202 if ((m->mtx_flags & MTX_RECURSE) == 0) 1203 panic("mutex_enter: recursion on non-recursive" 1204 " mutex %s @ %s:%d", m->mtx_description, 1205 file, line); 1206 return; 1207 } 1208 mtx_enter(&w_mtx, MTX_SPIN | MTX_QUIET); 1209 i = PCPU_GET(witness_spin_check); 1210 if (i != 0 && w->w_level < i) { 1211 mtx_exit(&w_mtx, MTX_SPIN | MTX_QUIET); 1212 panic("mutex_enter(%s:%x, MTX_SPIN) out of order @" 1213 " %s:%d already holding %s:%x", 1214 m->mtx_description, w->w_level, file, line, 1215 spin_order_list[ffs(i)-1], i); 1216 } 1217 PCPU_SET(witness_spin_check, i | w->w_level); 1218 mtx_exit(&w_mtx, MTX_SPIN | MTX_QUIET); 1219 w->w_file = file; 1220 w->w_line = line; 1221 m->mtx_line = line; 1222 m->mtx_file = file; 1223 return; 1224 } 1225 if ((m->mtx_flags & MTX_SPIN) != 0) 1226 panic("mutex_enter: MTX_DEF on MTX_SPIN mutex %s @ %s:%d", 1227 m->mtx_description, file, line); 1228 1229 if (mtx_recursed(m)) { 1230 if ((m->mtx_flags & MTX_RECURSE) == 0) 1231 panic("mutex_enter: recursion on non-recursive" 1232 " mutex %s @ %s:%d", m->mtx_description, 1233 file, line); 1234 return; 1235 } 1236 if (witness_dead) 1237 goto out; 1238 if (cold) 1239 goto out; 1240 1241 if (!mtx_legal2block()) 1242 panic("blockable mtx_enter() of %s when not legal @ %s:%d", 1243 m->mtx_description, file, line); 1244 /* 1245 * Is this the first mutex acquired 1246 */ 1247 if ((m1 = LIST_FIRST(&p->p_heldmtx)) == NULL) 1248 goto out; 1249 1250 if ((w1 = m1->mtx_witness) == w) { 1251 if (w->w_same_squawked || dup_ok(w)) 1252 goto out; 1253 w->w_same_squawked = 1; 1254 printf("acquring duplicate lock of same type: \"%s\"\n", 1255 m->mtx_description); 1256 printf(" 1st @ %s:%d\n", w->w_file, w->w_line); 1257 printf(" 2nd @ %s:%d\n", file, line); 1258#ifdef DDB 1259 go_into_ddb = 1; 1260#endif /* DDB */ 1261 goto out; 1262 } 1263 MPASS(!mtx_owned(&w_mtx)); 1264 mtx_enter(&w_mtx, MTX_SPIN | MTX_QUIET); 1265 /* 1266 * If we have a known higher number just say ok 1267 */ 1268 if (witness_watch > 1 && w->w_level > w1->w_level) { 1269 mtx_exit(&w_mtx, MTX_SPIN | MTX_QUIET); 1270 goto out; 1271 } 1272 if (isitmydescendant(m1->mtx_witness, w)) { 1273 mtx_exit(&w_mtx, MTX_SPIN | MTX_QUIET); 1274 goto out; 1275 } 1276 for (i = 0; m1 != NULL; m1 = LIST_NEXT(m1, mtx_held), i++) { 1277 1278 MPASS(i < 200); 1279 w1 = m1->mtx_witness; 1280 if (isitmydescendant(w, w1)) { 1281 mtx_exit(&w_mtx, MTX_SPIN | MTX_QUIET); 1282 if (blessed(w, w1)) 1283 goto out; 1284 if (m1 == &Giant) { 1285 if (w1->w_Giant_squawked) 1286 goto out; 1287 else 1288 w1->w_Giant_squawked = 1; 1289 } else { 1290 if (w1->w_other_squawked) 1291 goto out; 1292 else 1293 w1->w_other_squawked = 1; 1294 } 1295 printf("lock order reversal\n"); 1296 printf(" 1st %s last acquired @ %s:%d\n", 1297 w->w_description, w->w_file, w->w_line); 1298 printf(" 2nd %p %s @ %s:%d\n", 1299 m1, w1->w_description, w1->w_file, w1->w_line); 1300 printf(" 3rd %p %s @ %s:%d\n", 1301 m, w->w_description, file, line); 1302#ifdef DDB 1303 go_into_ddb = 1; 1304#endif /* DDB */ 1305 goto out; 1306 } 1307 } 1308 m1 = LIST_FIRST(&p->p_heldmtx); 1309 if (!itismychild(m1->mtx_witness, w)) 1310 mtx_exit(&w_mtx, MTX_SPIN | MTX_QUIET); 1311 1312out: 1313#ifdef DDB 1314 if (witness_ddb && go_into_ddb) 1315 Debugger("witness_enter"); 1316#endif /* DDB */ 1317 w->w_file = file; 1318 w->w_line = line; 1319 m->mtx_line = line; 1320 m->mtx_file = file; 1321 1322 /* 1323 * If this pays off it likely means that a mutex being witnessed 1324 * is acquired in hardclock. Put it in the ignore list. It is 1325 * likely not the mutex this assert fails on. 1326 */ 1327 MPASS(m->mtx_held.le_prev == NULL); 1328 LIST_INSERT_HEAD(&p->p_heldmtx, (struct mtx*)m, mtx_held); 1329} 1330 1331void 1332witness_try_enter(struct mtx *m, int flags, const char *file, int line) 1333{ 1334 struct proc *p; 1335 struct witness *w = m->mtx_witness; 1336 1337 if (witness_cold) 1338 return; 1339 if (panicstr) 1340 return; 1341 if (flags & MTX_SPIN) { 1342 if ((m->mtx_flags & MTX_SPIN) == 0) 1343 panic("mutex_try_enter: " 1344 "MTX_SPIN on MTX_DEF mutex %s @ %s:%d", 1345 m->mtx_description, file, line); 1346 if (mtx_recursed(m)) { 1347 if ((m->mtx_flags & MTX_RECURSE) == 0) 1348 panic("mutex_try_enter: recursion on" 1349 " non-recursive mutex %s @ %s:%d", 1350 m->mtx_description, file, line); 1351 return; 1352 } 1353 mtx_enter(&w_mtx, MTX_SPIN | MTX_QUIET); 1354 PCPU_SET(witness_spin_check, 1355 PCPU_GET(witness_spin_check) | w->w_level); 1356 mtx_exit(&w_mtx, MTX_SPIN | MTX_QUIET); 1357 w->w_file = file; 1358 w->w_line = line; 1359 m->mtx_line = line; 1360 m->mtx_file = file; 1361 return; 1362 } 1363 1364 if ((m->mtx_flags & MTX_SPIN) != 0) 1365 panic("mutex_try_enter: MTX_DEF on MTX_SPIN mutex %s @ %s:%d", 1366 m->mtx_description, file, line); 1367 1368 if (mtx_recursed(m)) { 1369 if ((m->mtx_flags & MTX_RECURSE) == 0) 1370 panic("mutex_try_enter: recursion on non-recursive" 1371 " mutex %s @ %s:%d", m->mtx_description, file, 1372 line); 1373 return; 1374 } 1375 w->w_file = file; 1376 w->w_line = line; 1377 m->mtx_line = line; 1378 m->mtx_file = file; 1379 p = CURPROC; 1380 MPASS(m->mtx_held.le_prev == NULL); 1381 LIST_INSERT_HEAD(&p->p_heldmtx, (struct mtx*)m, mtx_held); 1382} 1383 1384void 1385witness_exit(struct mtx *m, int flags, const char *file, int line) 1386{ 1387 struct witness *w; 1388 1389 if (witness_cold || m->mtx_witness == NULL || panicstr) 1390 return; 1391 w = m->mtx_witness; 1392 1393 if (flags & MTX_SPIN) { 1394 if ((m->mtx_flags & MTX_SPIN) == 0) 1395 panic("mutex_exit: MTX_SPIN on MTX_DEF mutex %s @" 1396 " %s:%d", m->mtx_description, file, line); 1397 if (mtx_recursed(m)) { 1398 if ((m->mtx_flags & MTX_RECURSE) == 0) 1399 panic("mutex_exit: recursion on non-recursive" 1400 " mutex %s @ %s:%d", m->mtx_description, 1401 file, line); 1402 return; 1403 } 1404 mtx_enter(&w_mtx, MTX_SPIN | MTX_QUIET); 1405 PCPU_SET(witness_spin_check, 1406 PCPU_GET(witness_spin_check) & ~w->w_level); 1407 mtx_exit(&w_mtx, MTX_SPIN | MTX_QUIET); 1408 return; 1409 } 1410 if ((m->mtx_flags & MTX_SPIN) != 0) 1411 panic("mutex_exit: MTX_DEF on MTX_SPIN mutex %s @ %s:%d", 1412 m->mtx_description, file, line); 1413 1414 if (mtx_recursed(m)) { 1415 if ((m->mtx_flags & MTX_RECURSE) == 0) 1416 panic("mutex_exit: recursion on non-recursive" 1417 " mutex %s @ %s:%d", m->mtx_description, 1418 file, line); 1419 return; 1420 } 1421 1422 if ((flags & MTX_NOSWITCH) == 0 && !mtx_legal2block() && !cold) 1423 panic("switchable mtx_exit() of %s when not legal @ %s:%d", 1424 m->mtx_description, file, line); 1425 LIST_REMOVE(m, mtx_held); 1426 m->mtx_held.le_prev = NULL; 1427} 1428 1429int 1430witness_sleep(int check_only, struct mtx *mtx, const char *file, int line) 1431{ 1432 struct mtx *m; 1433 struct proc *p; 1434 char **sleep; 1435 int n = 0; 1436 1437 KASSERT(!witness_cold, ("%s: witness_cold\n", __FUNCTION__)); 1438 p = CURPROC; 1439 for ((m = LIST_FIRST(&p->p_heldmtx)); m != NULL; 1440 m = LIST_NEXT(m, mtx_held)) { 1441 if (m == mtx) 1442 continue; 1443 for (sleep = sleep_list; *sleep!= NULL; sleep++) 1444 if (strcmp(m->mtx_description, *sleep) == 0) 1445 goto next; 1446 printf("%s:%d: %s with \"%s\" locked from %s:%d\n", 1447 file, line, check_only ? "could sleep" : "sleeping", 1448 m->mtx_description, 1449 m->mtx_witness->w_file, m->mtx_witness->w_line); 1450 n++; 1451 next: 1452 } 1453#ifdef DDB 1454 if (witness_ddb && n) 1455 Debugger("witness_sleep"); 1456#endif /* DDB */ 1457 return (n); 1458} 1459 1460static struct witness * 1461enroll(const char *description, int flag) 1462{ 1463 int i; 1464 struct witness *w, *w1; 1465 char **ignore; 1466 char **order; 1467 1468 if (!witness_watch) 1469 return (NULL); 1470 for (ignore = ignore_list; *ignore != NULL; ignore++) 1471 if (strcmp(description, *ignore) == 0) 1472 return (NULL); 1473 1474 if (w_inited == 0) { 1475 mtx_init(&w_mtx, "witness lock", MTX_SPIN); 1476 for (i = 0; i < WITNESS_COUNT; i++) { 1477 w = &w_data[i]; 1478 witness_free(w); 1479 } 1480 w_inited = 1; 1481 for (order = order_list; *order != NULL; order++) { 1482 w = enroll(*order, MTX_DEF); 1483 w->w_file = "order list"; 1484 for (order++; *order != NULL; order++) { 1485 w1 = enroll(*order, MTX_DEF); 1486 w1->w_file = "order list"; 1487 itismychild(w, w1); 1488 w = w1; 1489 } 1490 } 1491 } 1492 if ((flag & MTX_SPIN) && witness_skipspin) 1493 return (NULL); 1494 mtx_enter(&w_mtx, MTX_SPIN | MTX_QUIET); 1495 for (w = w_all; w; w = w->w_next) { 1496 if (strcmp(description, w->w_description) == 0) { 1497 mtx_exit(&w_mtx, MTX_SPIN | MTX_QUIET); 1498 return (w); 1499 } 1500 } 1501 if ((w = witness_get()) == NULL) 1502 return (NULL); 1503 w->w_next = w_all; 1504 w_all = w; 1505 w->w_description = description; 1506 mtx_exit(&w_mtx, MTX_SPIN | MTX_QUIET); 1507 if (flag & MTX_SPIN) { 1508 w->w_spin = 1; 1509 1510 i = 1; 1511 for (order = spin_order_list; *order != NULL; order++) { 1512 if (strcmp(description, *order) == 0) 1513 break; 1514 i <<= 1; 1515 } 1516 if (*order == NULL) 1517 panic("spin lock %s not in order list", description); 1518 w->w_level = i; 1519 } 1520 1521 return (w); 1522} 1523 1524static int 1525itismychild(struct witness *parent, struct witness *child) 1526{ 1527 static int recursed; 1528 1529 /* 1530 * Insert "child" after "parent" 1531 */ 1532 while (parent->w_morechildren) 1533 parent = parent->w_morechildren; 1534 1535 if (parent->w_childcnt == WITNESS_NCHILDREN) { 1536 if ((parent->w_morechildren = witness_get()) == NULL) 1537 return (1); 1538 parent = parent->w_morechildren; 1539 } 1540 MPASS(child != NULL); 1541 parent->w_children[parent->w_childcnt++] = child; 1542 /* 1543 * now prune whole tree 1544 */ 1545 if (recursed) 1546 return (0); 1547 recursed = 1; 1548 for (child = w_all; child != NULL; child = child->w_next) { 1549 for (parent = w_all; parent != NULL; 1550 parent = parent->w_next) { 1551 if (!isitmychild(parent, child)) 1552 continue; 1553 removechild(parent, child); 1554 if (isitmydescendant(parent, child)) 1555 continue; 1556 itismychild(parent, child); 1557 } 1558 } 1559 recursed = 0; 1560 witness_levelall(); 1561 return (0); 1562} 1563 1564static void 1565removechild(struct witness *parent, struct witness *child) 1566{ 1567 struct witness *w, *w1; 1568 int i; 1569 1570 for (w = parent; w != NULL; w = w->w_morechildren) 1571 for (i = 0; i < w->w_childcnt; i++) 1572 if (w->w_children[i] == child) 1573 goto found; 1574 return; 1575found: 1576 for (w1 = w; w1->w_morechildren != NULL; w1 = w1->w_morechildren) 1577 continue; 1578 w->w_children[i] = w1->w_children[--w1->w_childcnt]; 1579 MPASS(w->w_children[i] != NULL); 1580 1581 if (w1->w_childcnt != 0) 1582 return; 1583 1584 if (w1 == parent) 1585 return; 1586 for (w = parent; w->w_morechildren != w1; w = w->w_morechildren) 1587 continue; 1588 w->w_morechildren = 0; 1589 witness_free(w1); 1590} 1591 1592static int 1593isitmychild(struct witness *parent, struct witness *child) 1594{ 1595 struct witness *w; 1596 int i; 1597 1598 for (w = parent; w != NULL; w = w->w_morechildren) { 1599 for (i = 0; i < w->w_childcnt; i++) { 1600 if (w->w_children[i] == child) 1601 return (1); 1602 } 1603 } 1604 return (0); 1605} 1606 1607static int 1608isitmydescendant(struct witness *parent, struct witness *child) 1609{ 1610 struct witness *w; 1611 int i; 1612 int j; 1613 1614 for (j = 0, w = parent; w != NULL; w = w->w_morechildren, j++) { 1615 MPASS(j < 1000); 1616 for (i = 0; i < w->w_childcnt; i++) { 1617 if (w->w_children[i] == child) 1618 return (1); 1619 } 1620 for (i = 0; i < w->w_childcnt; i++) { 1621 if (isitmydescendant(w->w_children[i], child)) 1622 return (1); 1623 } 1624 } 1625 return (0); 1626} 1627 1628void 1629witness_levelall (void) 1630{ 1631 struct witness *w, *w1; 1632 1633 for (w = w_all; w; w = w->w_next) 1634 if (!(w->w_spin)) 1635 w->w_level = 0; 1636 for (w = w_all; w; w = w->w_next) { 1637 if (w->w_spin) 1638 continue; 1639 for (w1 = w_all; w1; w1 = w1->w_next) { 1640 if (isitmychild(w1, w)) 1641 break; 1642 } 1643 if (w1 != NULL) 1644 continue; 1645 witness_leveldescendents(w, 0); 1646 } 1647} 1648 1649static void 1650witness_leveldescendents(struct witness *parent, int level) 1651{ 1652 int i; 1653 struct witness *w; 1654 1655 if (parent->w_level < level) 1656 parent->w_level = level; 1657 level++; 1658 for (w = parent; w != NULL; w = w->w_morechildren) 1659 for (i = 0; i < w->w_childcnt; i++) 1660 witness_leveldescendents(w->w_children[i], level); 1661} 1662 1663static void 1664witness_displaydescendants(void(*prnt)(const char *fmt, ...), 1665 struct witness *parent) 1666{ 1667 struct witness *w; 1668 int i; 1669 int level = parent->w_level; 1670 1671 prnt("%d", level); 1672 if (level < 10) 1673 prnt(" "); 1674 for (i = 0; i < level; i++) 1675 prnt(" "); 1676 prnt("%s", parent->w_description); 1677 if (parent->w_file != NULL) { 1678 prnt(" -- last acquired @ %s", parent->w_file); 1679#ifndef W_USE_WHERE 1680 prnt(":%d", parent->w_line); 1681#endif 1682 prnt("\n"); 1683 } 1684 1685 for (w = parent; w != NULL; w = w->w_morechildren) 1686 for (i = 0; i < w->w_childcnt; i++) 1687 witness_displaydescendants(prnt, w->w_children[i]); 1688 } 1689 1690static int 1691dup_ok(struct witness *w) 1692{ 1693 char **dup; 1694 1695 for (dup = dup_list; *dup!= NULL; dup++) 1696 if (strcmp(w->w_description, *dup) == 0) 1697 return (1); 1698 return (0); 1699} 1700 1701static int 1702blessed(struct witness *w1, struct witness *w2) 1703{ 1704 int i; 1705 struct witness_blessed *b; 1706 1707 for (i = 0; i < blessed_count; i++) { 1708 b = &blessed_list[i]; 1709 if (strcmp(w1->w_description, b->b_lock1) == 0) { 1710 if (strcmp(w2->w_description, b->b_lock2) == 0) 1711 return (1); 1712 continue; 1713 } 1714 if (strcmp(w1->w_description, b->b_lock2) == 0) 1715 if (strcmp(w2->w_description, b->b_lock1) == 0) 1716 return (1); 1717 } 1718 return (0); 1719} 1720 1721static struct witness * 1722witness_get() 1723{ 1724 struct witness *w; 1725 1726 if ((w = w_free) == NULL) { 1727 witness_dead = 1; 1728 mtx_exit(&w_mtx, MTX_SPIN | MTX_QUIET); 1729 printf("witness exhausted\n"); 1730 return (NULL); 1731 } 1732 w_free = w->w_next; 1733 bzero(w, sizeof(*w)); 1734 return (w); 1735} 1736 1737static void 1738witness_free(struct witness *w) 1739{ 1740 w->w_next = w_free; 1741 w_free = w; 1742} 1743 1744int 1745witness_list(struct proc *p) 1746{ 1747 struct mtx *m; 1748 int nheld; 1749 1750 KASSERT(!witness_cold, ("%s: witness_cold\n", __FUNCTION__)); 1751 nheld = 0; 1752 for ((m = LIST_FIRST(&p->p_heldmtx)); m != NULL; 1753 m = LIST_NEXT(m, mtx_held)) { 1754 printf("\t\"%s\" (%p) locked at %s:%d\n", 1755 m->mtx_description, m, 1756 m->mtx_witness->w_file, m->mtx_witness->w_line); 1757 nheld++; 1758 } 1759 1760 return (nheld); 1761} 1762 1763void 1764witness_save(struct mtx *m, const char **filep, int *linep) 1765{ 1766 1767 KASSERT(!witness_cold, ("%s: witness_cold\n", __FUNCTION__)); 1768 if (m->mtx_witness == NULL) 1769 return; 1770 1771 *filep = m->mtx_witness->w_file; 1772 *linep = m->mtx_witness->w_line; 1773} 1774 1775void 1776witness_restore(struct mtx *m, const char *file, int line) 1777{ 1778 1779 KASSERT(!witness_cold, ("%s: witness_cold\n", __FUNCTION__)); 1780 if (m->mtx_witness == NULL) 1781 return; 1782 1783 m->mtx_witness->w_file = file; 1784 m->mtx_witness->w_line = line; 1785} 1786 1787#endif /* WITNESS */ 1788