subr_witness.c revision 69363
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 69363 2000-11-29 18:41:19Z 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/* All mutexes in system (used for debug/panic) */ 88#ifdef MUTEX_DEBUG 89static struct mtx_debug all_mtx_debug = { NULL, {NULL, NULL}, NULL, 0, 90 "All mutexes queue head" }; 91static struct mtx all_mtx = { MTX_UNOWNED, 0, 0, &all_mtx_debug, 92 TAILQ_HEAD_INITIALIZER(all_mtx.mtx_blocked), 93 { NULL, NULL }, &all_mtx, &all_mtx }; 94#else /* MUTEX_DEBUG */ 95static struct mtx all_mtx = { MTX_UNOWNED, 0, 0, "All mutexes queue head", 96 TAILQ_HEAD_INITIALIZER(all_mtx.mtx_blocked), 97 { NULL, NULL }, &all_mtx, &all_mtx }; 98#endif /* MUTEX_DEBUG */ 99 100static int mtx_cur_cnt; 101static int mtx_max_cnt; 102 103void _mtx_enter_giant_def(void); 104void _mtx_exit_giant_def(void); 105static void propagate_priority(struct proc *) __unused; 106 107#define mtx_unowned(m) ((m)->mtx_lock == MTX_UNOWNED) 108#define mtx_owner(m) (mtx_unowned(m) ? NULL \ 109 : (struct proc *)((m)->mtx_lock & MTX_FLAGMASK)) 110 111#define RETIP(x) *(((uintptr_t *)(&x)) - 1) 112#define SET_PRIO(p, pri) (p)->p_priority = (pri) 113 114/* 115 * XXX Temporary, for use from assembly language 116 */ 117 118void 119_mtx_enter_giant_def(void) 120{ 121 122 mtx_enter(&Giant, MTX_DEF); 123} 124 125void 126_mtx_exit_giant_def(void) 127{ 128 129 mtx_exit(&Giant, MTX_DEF); 130} 131 132static void 133propagate_priority(struct proc *p) 134{ 135 int pri = p->p_priority; 136 struct mtx *m = p->p_blocked; 137 138 for (;;) { 139 struct proc *p1; 140 141 p = mtx_owner(m); 142 143 if (p == NULL) { 144 /* 145 * This really isn't quite right. Really 146 * ought to bump priority of process that 147 * next acquires the mutex. 148 */ 149 MPASS(m->mtx_lock == MTX_CONTESTED); 150 return; 151 } 152 MPASS(p->p_magic == P_MAGIC); 153 if (p->p_priority <= pri) 154 return; 155 /* 156 * If lock holder is actually running, just bump priority. 157 */ 158 if (TAILQ_NEXT(p, p_procq) == NULL) { 159 MPASS(p->p_stat == SRUN || p->p_stat == SZOMB); 160 SET_PRIO(p, pri); 161 return; 162 } 163 /* 164 * If on run queue move to new run queue, and 165 * quit. 166 */ 167 if (p->p_stat == SRUN) { 168 MPASS(p->p_blocked == NULL); 169 remrunqueue(p); 170 SET_PRIO(p, pri); 171 setrunqueue(p); 172 return; 173 } 174 175 /* 176 * If we aren't blocked on a mutex, give up and quit. 177 */ 178 if (p->p_stat != SMTX) { 179 printf( 180 "XXX: process %d(%s):%d holds %s but isn't blocked on a mutex\n", 181 p->p_pid, p->p_comm, p->p_stat, m->mtx_description); 182 return; 183 } 184 185 /* 186 * Pick up the mutex that p is blocked on. 187 */ 188 m = p->p_blocked; 189 MPASS(m != NULL); 190 191 printf("XXX: process %d(%s) is blocked on %s\n", p->p_pid, 192 p->p_comm, m->mtx_description); 193 /* 194 * Check if the proc needs to be moved up on 195 * the blocked chain 196 */ 197 if ((p1 = TAILQ_PREV(p, rq, p_procq)) == NULL || 198 p1->p_priority <= pri) { 199 if (p1) 200 printf( 201 "XXX: previous process %d(%s) has higher priority\n", 202 p->p_pid, p->p_comm); 203 else 204 printf("XXX: process at head of run queue\n"); 205 continue; 206 } 207 208 /* 209 * Remove proc from blocked chain 210 */ 211 TAILQ_REMOVE(&m->mtx_blocked, p, p_procq); 212 TAILQ_FOREACH(p1, &m->mtx_blocked, p_procq) { 213 MPASS(p1->p_magic == P_MAGIC); 214 if (p1->p_priority > pri) 215 break; 216 } 217 if (p1) 218 TAILQ_INSERT_BEFORE(p1, p, p_procq); 219 else 220 TAILQ_INSERT_TAIL(&m->mtx_blocked, p, p_procq); 221 CTR4(KTR_LOCK, 222 "propagate priority: p 0x%p moved before 0x%p on [0x%p] %s", 223 p, p1, m, m->mtx_description); 224 } 225} 226 227void 228mtx_enter_hard(struct mtx *m, int type, int saveintr) 229{ 230 struct proc *p = CURPROC; 231 232 KASSERT(p != NULL, ("curproc is NULL in mutex")); 233 234 switch (type) { 235 case MTX_DEF: 236 if ((m->mtx_lock & MTX_FLAGMASK) == (uintptr_t)p) { 237 m->mtx_recurse++; 238 atomic_set_ptr(&m->mtx_lock, MTX_RECURSE); 239 CTR1(KTR_LOCK, "mtx_enter: 0x%p recurse", m); 240 return; 241 } 242 CTR3(KTR_LOCK, "mtx_enter: 0x%p contested (lock=%p) [0x%p]", 243 m, (void *)m->mtx_lock, (void *)RETIP(m)); 244 while (!_obtain_lock(m, p)) { 245 uintptr_t v; 246 struct proc *p1; 247 248 mtx_enter(&sched_lock, MTX_SPIN | MTX_RLIKELY); 249 /* 250 * check if the lock has been released while 251 * waiting for the schedlock. 252 */ 253 if ((v = m->mtx_lock) == MTX_UNOWNED) { 254 mtx_exit(&sched_lock, MTX_SPIN); 255 continue; 256 } 257 /* 258 * The mutex was marked contested on release. This 259 * means that there are processes blocked on it. 260 */ 261 if (v == MTX_CONTESTED) { 262 p1 = TAILQ_FIRST(&m->mtx_blocked); 263 KASSERT(p1 != NULL, ("contested mutex has no contesters")); 264 KASSERT(p != NULL, ("curproc is NULL for contested mutex")); 265 m->mtx_lock = (uintptr_t)p | MTX_CONTESTED; 266 if (p1->p_priority < p->p_priority) { 267 SET_PRIO(p, p1->p_priority); 268 } 269 mtx_exit(&sched_lock, MTX_SPIN); 270 return; 271 } 272 /* 273 * If the mutex isn't already contested and 274 * a failure occurs setting the contested bit the 275 * mutex was either release or the 276 * state of the RECURSION bit changed. 277 */ 278 if ((v & MTX_CONTESTED) == 0 && 279 !atomic_cmpset_ptr(&m->mtx_lock, (void *)v, 280 (void *)(v | MTX_CONTESTED))) { 281 mtx_exit(&sched_lock, MTX_SPIN); 282 continue; 283 } 284 285 /* We definitely have to sleep for this lock */ 286 mtx_assert(m, MA_NOTOWNED); 287 288#ifdef notyet 289 /* 290 * If we're borrowing an interrupted thread's VM 291 * context must clean up before going to sleep. 292 */ 293 if (p->p_flag & (P_ITHD | P_SITHD)) { 294 ithd_t *it = (ithd_t *)p; 295 296 if (it->it_interrupted) { 297 CTR2(KTR_LOCK, 298 "mtx_enter: 0x%x interrupted 0x%x", 299 it, it->it_interrupted); 300 intr_thd_fixup(it); 301 } 302 } 303#endif 304 305 /* Put us on the list of procs blocked on this mutex */ 306 if (TAILQ_EMPTY(&m->mtx_blocked)) { 307 p1 = (struct proc *)(m->mtx_lock & 308 MTX_FLAGMASK); 309 LIST_INSERT_HEAD(&p1->p_contested, m, 310 mtx_contested); 311 TAILQ_INSERT_TAIL(&m->mtx_blocked, p, p_procq); 312 } else { 313 TAILQ_FOREACH(p1, &m->mtx_blocked, p_procq) 314 if (p1->p_priority > p->p_priority) 315 break; 316 if (p1) 317 TAILQ_INSERT_BEFORE(p1, p, p_procq); 318 else 319 TAILQ_INSERT_TAIL(&m->mtx_blocked, p, 320 p_procq); 321 } 322 323 p->p_blocked = m; /* Who we're blocked on */ 324 p->p_stat = SMTX; 325#if 0 326 propagate_priority(p); 327#endif 328 CTR3(KTR_LOCK, "mtx_enter: p 0x%p blocked on [0x%p] %s", 329 p, m, m->mtx_description); 330 mi_switch(); 331 CTR3(KTR_LOCK, 332 "mtx_enter: p 0x%p free from blocked on [0x%p] %s", 333 p, m, m->mtx_description); 334 mtx_exit(&sched_lock, MTX_SPIN); 335 } 336 return; 337 case MTX_SPIN: 338 case MTX_SPIN | MTX_FIRST: 339 case MTX_SPIN | MTX_TOPHALF: 340 { 341 int i = 0; 342 343 if (m->mtx_lock == (uintptr_t)p) { 344 m->mtx_recurse++; 345 return; 346 } 347 CTR1(KTR_LOCK, "mtx_enter: %p spinning", m); 348 for (;;) { 349 if (_obtain_lock(m, p)) 350 break; 351 while (m->mtx_lock != MTX_UNOWNED) { 352 if (i++ < 1000000) 353 continue; 354 if (i++ < 6000000) 355 DELAY (1); 356#ifdef DDB 357 else if (!db_active) 358#else 359 else 360#endif 361 panic( 362 "spin lock %s held by 0x%p for > 5 seconds", 363 m->mtx_description, 364 (void *)m->mtx_lock); 365 } 366 } 367 368#ifdef MUTEX_DEBUG 369 if (type != MTX_SPIN) 370 m->mtx_saveintr = 0xbeefface; 371 else 372#endif 373 m->mtx_saveintr = saveintr; 374 CTR1(KTR_LOCK, "mtx_enter: 0x%p spin done", m); 375 return; 376 } 377 } 378} 379 380void 381mtx_exit_hard(struct mtx *m, int type) 382{ 383 struct proc *p, *p1; 384 struct mtx *m1; 385 int pri; 386 387 p = CURPROC; 388 switch (type) { 389 case MTX_DEF: 390 case MTX_DEF | MTX_NOSWITCH: 391 if (m->mtx_recurse != 0) { 392 if (--(m->mtx_recurse) == 0) 393 atomic_clear_ptr(&m->mtx_lock, MTX_RECURSE); 394 CTR1(KTR_LOCK, "mtx_exit: 0x%p unrecurse", m); 395 return; 396 } 397 mtx_enter(&sched_lock, MTX_SPIN); 398 CTR1(KTR_LOCK, "mtx_exit: 0x%p contested", m); 399 p1 = TAILQ_FIRST(&m->mtx_blocked); 400 MPASS(p->p_magic == P_MAGIC); 401 MPASS(p1->p_magic == P_MAGIC); 402 TAILQ_REMOVE(&m->mtx_blocked, p1, p_procq); 403 if (TAILQ_EMPTY(&m->mtx_blocked)) { 404 LIST_REMOVE(m, mtx_contested); 405 _release_lock_quick(m); 406 CTR1(KTR_LOCK, "mtx_exit: 0x%p not held", m); 407 } else 408 atomic_store_rel_ptr(&m->mtx_lock, 409 (void *)MTX_CONTESTED); 410 pri = MAXPRI; 411 LIST_FOREACH(m1, &p->p_contested, mtx_contested) { 412 int cp = TAILQ_FIRST(&m1->mtx_blocked)->p_priority; 413 if (cp < pri) 414 pri = cp; 415 } 416 if (pri > p->p_nativepri) 417 pri = p->p_nativepri; 418 SET_PRIO(p, pri); 419 CTR2(KTR_LOCK, "mtx_exit: 0x%p contested setrunqueue 0x%p", 420 m, p1); 421 p1->p_blocked = NULL; 422 p1->p_stat = SRUN; 423 setrunqueue(p1); 424 if ((type & MTX_NOSWITCH) == 0 && p1->p_priority < pri) { 425#ifdef notyet 426 if (p->p_flag & (P_ITHD | P_SITHD)) { 427 ithd_t *it = (ithd_t *)p; 428 429 if (it->it_interrupted) { 430 CTR2(KTR_LOCK, 431 "mtx_exit: 0x%x interruped 0x%x", 432 it, it->it_interrupted); 433 intr_thd_fixup(it); 434 } 435 } 436#endif 437 setrunqueue(p); 438 CTR2(KTR_LOCK, "mtx_exit: 0x%p switching out lock=0x%p", 439 m, (void *)m->mtx_lock); 440 mi_switch(); 441 CTR2(KTR_LOCK, "mtx_exit: 0x%p resuming lock=0x%p", 442 m, (void *)m->mtx_lock); 443 } 444 mtx_exit(&sched_lock, MTX_SPIN); 445 break; 446 case MTX_SPIN: 447 case MTX_SPIN | MTX_FIRST: 448 if (m->mtx_recurse != 0) { 449 m->mtx_recurse--; 450 return; 451 } 452 MPASS(mtx_owned(m)); 453 _release_lock_quick(m); 454 if (type & MTX_FIRST) 455 enable_intr(); /* XXX is this kosher? */ 456 else { 457 MPASS(m->mtx_saveintr != 0xbeefface); 458 restore_intr(m->mtx_saveintr); 459 } 460 break; 461 case MTX_SPIN | MTX_TOPHALF: 462 if (m->mtx_recurse != 0) { 463 m->mtx_recurse--; 464 return; 465 } 466 MPASS(mtx_owned(m)); 467 _release_lock_quick(m); 468 break; 469 default: 470 panic("mtx_exit_hard: unsupported type 0x%x\n", type); 471 } 472} 473 474#define MV_DESTROY 0 /* validate before destory */ 475#define MV_INIT 1 /* validate before init */ 476 477#ifdef MUTEX_DEBUG 478 479int mtx_validate __P((struct mtx *, int)); 480 481int 482mtx_validate(struct mtx *m, int when) 483{ 484 struct mtx *mp; 485 int i; 486 int retval = 0; 487 488 if (m == &all_mtx || cold) 489 return 0; 490 491 mtx_enter(&all_mtx, MTX_DEF); 492/* 493 * XXX - When kernacc() is fixed on the alpha to handle K0_SEG memory properly 494 * we can re-enable the kernacc() checks. 495 */ 496#ifndef __alpha__ 497 MPASS(kernacc((caddr_t)all_mtx.mtx_next, sizeof(uintptr_t), 498 VM_PROT_READ) == 1); 499#endif 500 MPASS(all_mtx.mtx_next->mtx_prev == &all_mtx); 501 for (i = 0, mp = all_mtx.mtx_next; mp != &all_mtx; mp = mp->mtx_next) { 502#ifndef __alpha__ 503 if (kernacc((caddr_t)mp->mtx_next, sizeof(uintptr_t), 504 VM_PROT_READ) != 1) { 505 panic("mtx_validate: mp=%p mp->mtx_next=%p", 506 mp, mp->mtx_next); 507 } 508#endif 509 i++; 510 if (i > mtx_cur_cnt) { 511 panic("mtx_validate: too many in chain, known=%d\n", 512 mtx_cur_cnt); 513 } 514 } 515 MPASS(i == mtx_cur_cnt); 516 switch (when) { 517 case MV_DESTROY: 518 for (mp = all_mtx.mtx_next; mp != &all_mtx; mp = mp->mtx_next) 519 if (mp == m) 520 break; 521 MPASS(mp == m); 522 break; 523 case MV_INIT: 524 for (mp = all_mtx.mtx_next; mp != &all_mtx; mp = mp->mtx_next) 525 if (mp == m) { 526 /* 527 * Not good. This mutex already exists. 528 */ 529 printf("re-initing existing mutex %s\n", 530 m->mtx_description); 531 MPASS(m->mtx_lock == MTX_UNOWNED); 532 retval = 1; 533 } 534 } 535 mtx_exit(&all_mtx, MTX_DEF); 536 return (retval); 537} 538#endif 539 540void 541mtx_init(struct mtx *m, const char *t, int flag) 542{ 543#ifdef MUTEX_DEBUG 544 struct mtx_debug *debug; 545#endif 546 547 CTR2(KTR_LOCK, "mtx_init 0x%p (%s)", m, t); 548#ifdef MUTEX_DEBUG 549 if (mtx_validate(m, MV_INIT)) /* diagnostic and error correction */ 550 return; 551 if (flag & MTX_COLD) 552 debug = m->mtx_debug; 553 else 554 debug = NULL; 555 if (debug == NULL) { 556#ifdef DIAGNOSTIC 557 if(cold && bootverbose) 558 printf("malloc'ing mtx_debug while cold for %s\n", t); 559#endif 560 561 /* XXX - should not use DEVBUF */ 562 debug = malloc(sizeof(struct mtx_debug), M_DEVBUF, M_NOWAIT); 563 MPASS(debug != NULL); 564 bzero(debug, sizeof(struct mtx_debug)); 565 } 566#endif 567 bzero((void *)m, sizeof *m); 568 TAILQ_INIT(&m->mtx_blocked); 569#ifdef MUTEX_DEBUG 570 m->mtx_debug = debug; 571#endif 572 m->mtx_description = t; 573 m->mtx_lock = MTX_UNOWNED; 574 /* Put on all mutex queue */ 575 mtx_enter(&all_mtx, MTX_DEF); 576 m->mtx_next = &all_mtx; 577 m->mtx_prev = all_mtx.mtx_prev; 578 m->mtx_prev->mtx_next = m; 579 all_mtx.mtx_prev = m; 580 if (++mtx_cur_cnt > mtx_max_cnt) 581 mtx_max_cnt = mtx_cur_cnt; 582 mtx_exit(&all_mtx, MTX_DEF); 583 witness_init(m, flag); 584} 585 586void 587mtx_destroy(struct mtx *m) 588{ 589 590 CTR2(KTR_LOCK, "mtx_destroy 0x%p (%s)", m, m->mtx_description); 591#ifdef MUTEX_DEBUG 592 if (m->mtx_next == NULL) 593 panic("mtx_destroy: %p (%s) already destroyed", 594 m, m->mtx_description); 595 596 if (!mtx_owned(m)) { 597 MPASS(m->mtx_lock == MTX_UNOWNED); 598 } else { 599 MPASS((m->mtx_lock & (MTX_RECURSE|MTX_CONTESTED)) == 0); 600 } 601 mtx_validate(m, MV_DESTROY); /* diagnostic */ 602#endif 603 604#ifdef WITNESS 605 if (m->mtx_witness) 606 witness_destroy(m); 607#endif /* WITNESS */ 608 609 /* Remove from the all mutex queue */ 610 mtx_enter(&all_mtx, MTX_DEF); 611 m->mtx_next->mtx_prev = m->mtx_prev; 612 m->mtx_prev->mtx_next = m->mtx_next; 613#ifdef MUTEX_DEBUG 614 m->mtx_next = m->mtx_prev = NULL; 615 free(m->mtx_debug, M_DEVBUF); 616 m->mtx_debug = NULL; 617#endif 618 mtx_cur_cnt--; 619 mtx_exit(&all_mtx, MTX_DEF); 620} 621 622/* 623 * The non-inlined versions of the mtx_*() functions are always built (above), 624 * but the witness code depends on the MUTEX_DEBUG and WITNESS kernel options 625 * being specified. 626 */ 627#if (defined(MUTEX_DEBUG) && defined(WITNESS)) 628 629#define WITNESS_COUNT 200 630#define WITNESS_NCHILDREN 2 631 632int witness_watch = 1; 633 634struct witness { 635 struct witness *w_next; 636 const char *w_description; 637 const char *w_file; 638 int w_line; 639 struct witness *w_morechildren; 640 u_char w_childcnt; 641 u_char w_Giant_squawked:1; 642 u_char w_other_squawked:1; 643 u_char w_same_squawked:1; 644 u_char w_sleep:1; 645 u_char w_spin:1; /* this is a spin mutex */ 646 u_int w_level; 647 struct witness *w_children[WITNESS_NCHILDREN]; 648}; 649 650struct witness_blessed { 651 char *b_lock1; 652 char *b_lock2; 653}; 654 655#ifdef DDB 656/* 657 * When DDB is enabled and witness_ddb is set to 1, it will cause the system to 658 * drop into kdebug() when: 659 * - a lock heirarchy violation occurs 660 * - locks are held when going to sleep. 661 */ 662#ifdef WITNESS_DDB 663int witness_ddb = 1; 664#else 665int witness_ddb = 0; 666#endif 667SYSCTL_INT(_debug, OID_AUTO, witness_ddb, CTLFLAG_RW, &witness_ddb, 0, ""); 668#endif /* DDB */ 669 670#ifdef WITNESS_SKIPSPIN 671int witness_skipspin = 1; 672#else 673int witness_skipspin = 0; 674#endif 675SYSCTL_INT(_debug, OID_AUTO, witness_skipspin, CTLFLAG_RD, &witness_skipspin, 0, 676 ""); 677 678MUTEX_DECLARE(static,w_mtx); 679static struct witness *w_free; 680static struct witness *w_all; 681static int w_inited; 682static int witness_dead; /* fatal error, probably no memory */ 683 684static struct witness w_data[WITNESS_COUNT]; 685 686static struct witness *enroll __P((const char *description, int flag)); 687static int itismychild __P((struct witness *parent, struct witness *child)); 688static void removechild __P((struct witness *parent, struct witness *child)); 689static int isitmychild __P((struct witness *parent, struct witness *child)); 690static int isitmydescendant __P((struct witness *parent, struct witness *child)); 691static int dup_ok __P((struct witness *)); 692static int blessed __P((struct witness *, struct witness *)); 693static void witness_displaydescendants 694 __P((void(*)(const char *fmt, ...), struct witness *)); 695static void witness_leveldescendents __P((struct witness *parent, int level)); 696static void witness_levelall __P((void)); 697static struct witness * witness_get __P((void)); 698static void witness_free __P((struct witness *m)); 699 700 701static char *ignore_list[] = { 702 "witness lock", 703 NULL 704}; 705 706static char *spin_order_list[] = { 707 "sio", 708 "sched lock", 709#ifdef __i386__ 710 "clk", 711#endif 712 "callout", 713 /* 714 * leaf locks 715 */ 716 NULL 717}; 718 719static char *order_list[] = { 720 "uidinfo hash", "uidinfo struct", NULL, 721 NULL 722}; 723 724static char *dup_list[] = { 725 NULL 726}; 727 728static char *sleep_list[] = { 729 "Giant", 730 NULL 731}; 732 733/* 734 * Pairs of locks which have been blessed 735 * Don't complain about order problems with blessed locks 736 */ 737static struct witness_blessed blessed_list[] = { 738}; 739static int blessed_count = sizeof(blessed_list) / sizeof(struct witness_blessed); 740 741void 742witness_init(struct mtx *m, int flag) 743{ 744 m->mtx_witness = enroll(m->mtx_description, flag); 745} 746 747void 748witness_destroy(struct mtx *m) 749{ 750 struct mtx *m1; 751 struct proc *p; 752 p = CURPROC; 753 for ((m1 = LIST_FIRST(&p->p_heldmtx)); m1 != NULL; 754 m1 = LIST_NEXT(m1, mtx_held)) { 755 if (m1 == m) { 756 LIST_REMOVE(m, mtx_held); 757 break; 758 } 759 } 760 return; 761 762} 763 764void 765witness_enter(struct mtx *m, int flags, const char *file, int line) 766{ 767 struct witness *w, *w1; 768 struct mtx *m1; 769 struct proc *p; 770 int i; 771#ifdef DDB 772 int go_into_ddb = 0; 773#endif /* DDB */ 774 775 w = m->mtx_witness; 776 p = CURPROC; 777 778 if (flags & MTX_SPIN) { 779 if (!w->w_spin) 780 panic("mutex_enter: MTX_SPIN on MTX_DEF mutex %s @" 781 " %s:%d", m->mtx_description, file, line); 782 if (m->mtx_recurse != 0) 783 return; 784 mtx_enter(&w_mtx, MTX_SPIN); 785 i = witness_spin_check; 786 if (i != 0 && w->w_level < i) { 787 mtx_exit(&w_mtx, MTX_SPIN); 788 panic("mutex_enter(%s:%x, MTX_SPIN) out of order @" 789 " %s:%d already holding %s:%x", 790 m->mtx_description, w->w_level, file, line, 791 spin_order_list[ffs(i)-1], i); 792 } 793 PCPU_SET(witness_spin_check, i | w->w_level); 794 mtx_exit(&w_mtx, MTX_SPIN); 795 w->w_file = file; 796 w->w_line = line; 797 m->mtx_line = line; 798 m->mtx_file = file; 799 return; 800 } 801 if (w->w_spin) 802 panic("mutex_enter: MTX_DEF on MTX_SPIN mutex %s @ %s:%d", 803 m->mtx_description, file, line); 804 805 if (m->mtx_recurse != 0) 806 return; 807 if (witness_dead) 808 goto out; 809 if (cold || panicstr) 810 goto out; 811 812 if (!mtx_legal2block()) 813 panic("blockable mtx_enter() of %s when not legal @ %s:%d", 814 m->mtx_description, file, line); 815 /* 816 * Is this the first mutex acquired 817 */ 818 if ((m1 = LIST_FIRST(&p->p_heldmtx)) == NULL) 819 goto out; 820 821 if ((w1 = m1->mtx_witness) == w) { 822 if (w->w_same_squawked || dup_ok(w)) 823 goto out; 824 w->w_same_squawked = 1; 825 printf("acquring duplicate lock of same type: \"%s\"\n", 826 m->mtx_description); 827 printf(" 1st @ %s:%d\n", w->w_file, w->w_line); 828 printf(" 2nd @ %s:%d\n", file, line); 829#ifdef DDB 830 go_into_ddb = 1; 831#endif /* DDB */ 832 goto out; 833 } 834 MPASS(!mtx_owned(&w_mtx)); 835 mtx_enter(&w_mtx, MTX_SPIN); 836 /* 837 * If we have a known higher number just say ok 838 */ 839 if (witness_watch > 1 && w->w_level > w1->w_level) { 840 mtx_exit(&w_mtx, MTX_SPIN); 841 goto out; 842 } 843 if (isitmydescendant(m1->mtx_witness, w)) { 844 mtx_exit(&w_mtx, MTX_SPIN); 845 goto out; 846 } 847 for (i = 0; m1 != NULL; m1 = LIST_NEXT(m1, mtx_held), i++) { 848 849 MPASS(i < 200); 850 w1 = m1->mtx_witness; 851 if (isitmydescendant(w, w1)) { 852 mtx_exit(&w_mtx, MTX_SPIN); 853 if (blessed(w, w1)) 854 goto out; 855 if (m1 == &Giant) { 856 if (w1->w_Giant_squawked) 857 goto out; 858 else 859 w1->w_Giant_squawked = 1; 860 } else { 861 if (w1->w_other_squawked) 862 goto out; 863 else 864 w1->w_other_squawked = 1; 865 } 866 printf("lock order reversal\n"); 867 printf(" 1st %s last acquired @ %s:%d\n", 868 w->w_description, w->w_file, w->w_line); 869 printf(" 2nd %p %s @ %s:%d\n", 870 m1, w1->w_description, w1->w_file, w1->w_line); 871 printf(" 3rd %p %s @ %s:%d\n", 872 m, w->w_description, file, line); 873#ifdef DDB 874 go_into_ddb = 1; 875#endif /* DDB */ 876 goto out; 877 } 878 } 879 m1 = LIST_FIRST(&p->p_heldmtx); 880 if (!itismychild(m1->mtx_witness, w)) 881 mtx_exit(&w_mtx, MTX_SPIN); 882 883out: 884#ifdef DDB 885 if (witness_ddb && go_into_ddb) 886 Debugger("witness_enter"); 887#endif /* DDB */ 888 w->w_file = file; 889 w->w_line = line; 890 m->mtx_line = line; 891 m->mtx_file = file; 892 893 /* 894 * If this pays off it likely means that a mutex being witnessed 895 * is acquired in hardclock. Put it in the ignore list. It is 896 * likely not the mutex this assert fails on. 897 */ 898 MPASS(m->mtx_held.le_prev == NULL); 899 LIST_INSERT_HEAD(&p->p_heldmtx, (struct mtx*)m, mtx_held); 900} 901 902void 903witness_exit(struct mtx *m, int flags, const char *file, int line) 904{ 905 struct witness *w; 906 907 w = m->mtx_witness; 908 909 if (flags & MTX_SPIN) { 910 if (!w->w_spin) 911 panic("mutex_exit: MTX_SPIN on MTX_DEF mutex %s @" 912 " %s:%d", m->mtx_description, file, line); 913 if (m->mtx_recurse != 0) 914 return; 915 mtx_enter(&w_mtx, MTX_SPIN); 916 PCPU_SET(witness_spin_check, witness_spin_check & ~w->w_level); 917 mtx_exit(&w_mtx, MTX_SPIN); 918 return; 919 } 920 if (w->w_spin) 921 panic("mutex_exit: MTX_DEF on MTX_SPIN mutex %s @ %s:%d", 922 m->mtx_description, file, line); 923 924 if (m->mtx_recurse != 0) 925 return; 926 927 if ((flags & MTX_NOSWITCH) == 0 && !mtx_legal2block() && !cold) 928 panic("switchable mtx_exit() of %s when not legal @ %s:%d", 929 m->mtx_description, file, line); 930 LIST_REMOVE(m, mtx_held); 931 m->mtx_held.le_prev = NULL; 932} 933 934void 935witness_try_enter(struct mtx *m, int flags, const char *file, int line) 936{ 937 struct proc *p; 938 struct witness *w = m->mtx_witness; 939 940 if (flags & MTX_SPIN) { 941 if (!w->w_spin) 942 panic("mutex_try_enter: " 943 "MTX_SPIN on MTX_DEF mutex %s @ %s:%d", 944 m->mtx_description, file, line); 945 if (m->mtx_recurse != 0) 946 return; 947 mtx_enter(&w_mtx, MTX_SPIN); 948 PCPU_SET(witness_spin_check, witness_spin_check | w->w_level); 949 mtx_exit(&w_mtx, MTX_SPIN); 950 w->w_file = file; 951 w->w_line = line; 952 m->mtx_line = line; 953 m->mtx_file = file; 954 return; 955 } 956 957 if (w->w_spin) 958 panic("mutex_try_enter: MTX_DEF on MTX_SPIN mutex %s @ %s:%d", 959 m->mtx_description, file, line); 960 961 if (m->mtx_recurse != 0) 962 return; 963 964 w->w_file = file; 965 w->w_line = line; 966 m->mtx_line = line; 967 m->mtx_file = file; 968 p = CURPROC; 969 MPASS(m->mtx_held.le_prev == NULL); 970 LIST_INSERT_HEAD(&p->p_heldmtx, (struct mtx*)m, mtx_held); 971} 972 973void 974witness_display(void(*prnt)(const char *fmt, ...)) 975{ 976 struct witness *w, *w1; 977 978 witness_levelall(); 979 980 for (w = w_all; w; w = w->w_next) { 981 if (w->w_file == NULL) 982 continue; 983 for (w1 = w_all; w1; w1 = w1->w_next) { 984 if (isitmychild(w1, w)) 985 break; 986 } 987 if (w1 != NULL) 988 continue; 989 /* 990 * This lock has no anscestors, display its descendants. 991 */ 992 witness_displaydescendants(prnt, w); 993 } 994 prnt("\nMutex which were never acquired\n"); 995 for (w = w_all; w; w = w->w_next) { 996 if (w->w_file != NULL) 997 continue; 998 prnt("%s\n", w->w_description); 999 } 1000} 1001 1002int 1003witness_sleep(int check_only, struct mtx *mtx, const char *file, int line) 1004{ 1005 struct mtx *m; 1006 struct proc *p; 1007 char **sleep; 1008 int n = 0; 1009 1010 p = CURPROC; 1011 for ((m = LIST_FIRST(&p->p_heldmtx)); m != NULL; 1012 m = LIST_NEXT(m, mtx_held)) { 1013 if (m == mtx) 1014 continue; 1015 for (sleep = sleep_list; *sleep!= NULL; sleep++) 1016 if (strcmp(m->mtx_description, *sleep) == 0) 1017 goto next; 1018 printf("%s:%d: %s with \"%s\" locked from %s:%d\n", 1019 file, line, check_only ? "could sleep" : "sleeping", 1020 m->mtx_description, 1021 m->mtx_witness->w_file, m->mtx_witness->w_line); 1022 n++; 1023 next: 1024 } 1025#ifdef DDB 1026 if (witness_ddb && n) 1027 Debugger("witness_sleep"); 1028#endif /* DDB */ 1029 return (n); 1030} 1031 1032static struct witness * 1033enroll(const char *description, int flag) 1034{ 1035 int i; 1036 struct witness *w, *w1; 1037 char **ignore; 1038 char **order; 1039 1040 if (!witness_watch) 1041 return (NULL); 1042 for (ignore = ignore_list; *ignore != NULL; ignore++) 1043 if (strcmp(description, *ignore) == 0) 1044 return (NULL); 1045 1046 if (w_inited == 0) { 1047 mtx_init(&w_mtx, "witness lock", MTX_COLD | MTX_DEF); 1048 for (i = 0; i < WITNESS_COUNT; i++) { 1049 w = &w_data[i]; 1050 witness_free(w); 1051 } 1052 w_inited = 1; 1053 for (order = order_list; *order != NULL; order++) { 1054 w = enroll(*order, MTX_DEF); 1055 w->w_file = "order list"; 1056 for (order++; *order != NULL; order++) { 1057 w1 = enroll(*order, MTX_DEF); 1058 w1->w_file = "order list"; 1059 itismychild(w, w1); 1060 w = w1; 1061 } 1062 } 1063 } 1064 if ((flag & MTX_SPIN) && witness_skipspin) 1065 return (NULL); 1066 mtx_enter(&w_mtx, MTX_SPIN); 1067 for (w = w_all; w; w = w->w_next) { 1068 if (strcmp(description, w->w_description) == 0) { 1069 mtx_exit(&w_mtx, MTX_SPIN); 1070 return (w); 1071 } 1072 } 1073 if ((w = witness_get()) == NULL) 1074 return (NULL); 1075 w->w_next = w_all; 1076 w_all = w; 1077 w->w_description = description; 1078 mtx_exit(&w_mtx, MTX_SPIN); 1079 if (flag & MTX_SPIN) { 1080 w->w_spin = 1; 1081 1082 i = 1; 1083 for (order = spin_order_list; *order != NULL; order++) { 1084 if (strcmp(description, *order) == 0) 1085 break; 1086 i <<= 1; 1087 } 1088 if (*order == NULL) 1089 panic("spin lock %s not in order list", description); 1090 w->w_level = i; 1091 } 1092 return (w); 1093} 1094 1095static int 1096itismychild(struct witness *parent, struct witness *child) 1097{ 1098 static int recursed; 1099 1100 /* 1101 * Insert "child" after "parent" 1102 */ 1103 while (parent->w_morechildren) 1104 parent = parent->w_morechildren; 1105 1106 if (parent->w_childcnt == WITNESS_NCHILDREN) { 1107 if ((parent->w_morechildren = witness_get()) == NULL) 1108 return (1); 1109 parent = parent->w_morechildren; 1110 } 1111 MPASS(child != NULL); 1112 parent->w_children[parent->w_childcnt++] = child; 1113 /* 1114 * now prune whole tree 1115 */ 1116 if (recursed) 1117 return (0); 1118 recursed = 1; 1119 for (child = w_all; child != NULL; child = child->w_next) { 1120 for (parent = w_all; parent != NULL; 1121 parent = parent->w_next) { 1122 if (!isitmychild(parent, child)) 1123 continue; 1124 removechild(parent, child); 1125 if (isitmydescendant(parent, child)) 1126 continue; 1127 itismychild(parent, child); 1128 } 1129 } 1130 recursed = 0; 1131 witness_levelall(); 1132 return (0); 1133} 1134 1135static void 1136removechild(struct witness *parent, struct witness *child) 1137{ 1138 struct witness *w, *w1; 1139 int i; 1140 1141 for (w = parent; w != NULL; w = w->w_morechildren) 1142 for (i = 0; i < w->w_childcnt; i++) 1143 if (w->w_children[i] == child) 1144 goto found; 1145 return; 1146found: 1147 for (w1 = w; w1->w_morechildren != NULL; w1 = w1->w_morechildren) 1148 continue; 1149 w->w_children[i] = w1->w_children[--w1->w_childcnt]; 1150 MPASS(w->w_children[i] != NULL); 1151 1152 if (w1->w_childcnt != 0) 1153 return; 1154 1155 if (w1 == parent) 1156 return; 1157 for (w = parent; w->w_morechildren != w1; w = w->w_morechildren) 1158 continue; 1159 w->w_morechildren = 0; 1160 witness_free(w1); 1161} 1162 1163static int 1164isitmychild(struct witness *parent, struct witness *child) 1165{ 1166 struct witness *w; 1167 int i; 1168 1169 for (w = parent; w != NULL; w = w->w_morechildren) { 1170 for (i = 0; i < w->w_childcnt; i++) { 1171 if (w->w_children[i] == child) 1172 return (1); 1173 } 1174 } 1175 return (0); 1176} 1177 1178static int 1179isitmydescendant(struct witness *parent, struct witness *child) 1180{ 1181 struct witness *w; 1182 int i; 1183 int j; 1184 1185 for (j = 0, w = parent; w != NULL; w = w->w_morechildren, j++) { 1186 MPASS(j < 1000); 1187 for (i = 0; i < w->w_childcnt; i++) { 1188 if (w->w_children[i] == child) 1189 return (1); 1190 } 1191 for (i = 0; i < w->w_childcnt; i++) { 1192 if (isitmydescendant(w->w_children[i], child)) 1193 return (1); 1194 } 1195 } 1196 return (0); 1197} 1198 1199void 1200witness_levelall (void) 1201{ 1202 struct witness *w, *w1; 1203 1204 for (w = w_all; w; w = w->w_next) 1205 if (!w->w_spin) 1206 w->w_level = 0; 1207 for (w = w_all; w; w = w->w_next) { 1208 if (w->w_spin) 1209 continue; 1210 for (w1 = w_all; w1; w1 = w1->w_next) { 1211 if (isitmychild(w1, w)) 1212 break; 1213 } 1214 if (w1 != NULL) 1215 continue; 1216 witness_leveldescendents(w, 0); 1217 } 1218} 1219 1220static void 1221witness_leveldescendents(struct witness *parent, int level) 1222{ 1223 int i; 1224 struct witness *w; 1225 1226 if (parent->w_level < level) 1227 parent->w_level = level; 1228 level++; 1229 for (w = parent; w != NULL; w = w->w_morechildren) 1230 for (i = 0; i < w->w_childcnt; i++) 1231 witness_leveldescendents(w->w_children[i], level); 1232} 1233 1234static void 1235witness_displaydescendants(void(*prnt)(const char *fmt, ...), 1236 struct witness *parent) 1237{ 1238 struct witness *w; 1239 int i; 1240 int level = parent->w_level; 1241 1242 prnt("%d", level); 1243 if (level < 10) 1244 prnt(" "); 1245 for (i = 0; i < level; i++) 1246 prnt(" "); 1247 prnt("%s", parent->w_description); 1248 if (parent->w_file != NULL) { 1249 prnt(" -- last acquired @ %s", parent->w_file); 1250#ifndef W_USE_WHERE 1251 prnt(":%d", parent->w_line); 1252#endif 1253 prnt("\n"); 1254 } 1255 1256 for (w = parent; w != NULL; w = w->w_morechildren) 1257 for (i = 0; i < w->w_childcnt; i++) 1258 witness_displaydescendants(prnt, w->w_children[i]); 1259 } 1260 1261static int 1262dup_ok(struct witness *w) 1263{ 1264 char **dup; 1265 1266 for (dup = dup_list; *dup!= NULL; dup++) 1267 if (strcmp(w->w_description, *dup) == 0) 1268 return (1); 1269 return (0); 1270} 1271 1272static int 1273blessed(struct witness *w1, struct witness *w2) 1274{ 1275 int i; 1276 struct witness_blessed *b; 1277 1278 for (i = 0; i < blessed_count; i++) { 1279 b = &blessed_list[i]; 1280 if (strcmp(w1->w_description, b->b_lock1) == 0) { 1281 if (strcmp(w2->w_description, b->b_lock2) == 0) 1282 return (1); 1283 continue; 1284 } 1285 if (strcmp(w1->w_description, b->b_lock2) == 0) 1286 if (strcmp(w2->w_description, b->b_lock1) == 0) 1287 return (1); 1288 } 1289 return (0); 1290} 1291 1292static struct witness * 1293witness_get() 1294{ 1295 struct witness *w; 1296 1297 if ((w = w_free) == NULL) { 1298 witness_dead = 1; 1299 mtx_exit(&w_mtx, MTX_SPIN); 1300 printf("witness exhausted\n"); 1301 return (NULL); 1302 } 1303 w_free = w->w_next; 1304 bzero(w, sizeof(*w)); 1305 return (w); 1306} 1307 1308static void 1309witness_free(struct witness *w) 1310{ 1311 w->w_next = w_free; 1312 w_free = w; 1313} 1314 1315void 1316witness_list(struct proc *p) 1317{ 1318 struct mtx *m; 1319 1320 for ((m = LIST_FIRST(&p->p_heldmtx)); m != NULL; 1321 m = LIST_NEXT(m, mtx_held)) { 1322 printf("\t\"%s\" (%p) locked at %s:%d\n", 1323 m->mtx_description, m, 1324 m->mtx_witness->w_file, m->mtx_witness->w_line); 1325 } 1326} 1327 1328void 1329witness_save(struct mtx *m, const char **filep, int *linep) 1330{ 1331 *filep = m->mtx_witness->w_file; 1332 *linep = m->mtx_witness->w_line; 1333} 1334 1335void 1336witness_restore(struct mtx *m, const char *file, int line) 1337{ 1338 m->mtx_witness->w_file = file; 1339 m->mtx_witness->w_line = line; 1340} 1341 1342#endif /* (defined(MUTEX_DEBUG) && defined(WITNESS)) */ 1343