subr_witness.c revision 77900
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 77900 2001-06-08 05:24:21Z peter $ 31 */ 32 33/* 34 * Implementation of the `witness' lock verifier. Originally implemented for 35 * mutexes in BSD/OS. Extended to handle generic lock objects and lock 36 * classes in FreeBSD. 37 */ 38 39/* 40 * Main Entry: witness 41 * Pronunciation: 'wit-n&s 42 * Function: noun 43 * Etymology: Middle English witnesse, from Old English witnes knowledge, 44 * testimony, witness, from 2wit 45 * Date: before 12th century 46 * 1 : attestation of a fact or event : TESTIMONY 47 * 2 : one that gives evidence; specifically : one who testifies in 48 * a cause or before a judicial tribunal 49 * 3 : one asked to be present at a transaction so as to be able to 50 * testify to its having taken place 51 * 4 : one who has personal knowledge of something 52 * 5 a : something serving as evidence or proof : SIGN 53 * b : public affirmation by word or example of usually 54 * religious faith or conviction <the heroic witness to divine 55 * life -- Pilot> 56 * 6 capitalized : a member of the Jehovah's Witnesses 57 */ 58 59#include "opt_ddb.h" 60#include "opt_witness.h" 61 62#include <sys/param.h> 63#include <sys/bus.h> 64#include <sys/kernel.h> 65#include <sys/ktr.h> 66#include <sys/lock.h> 67#include <sys/malloc.h> 68#include <sys/mutex.h> 69#include <sys/proc.h> 70#include <sys/sysctl.h> 71#include <sys/systm.h> 72 73#include <ddb/ddb.h> 74 75#define WITNESS_COUNT 200 76#define WITNESS_CHILDCOUNT (WITNESS_COUNT * 4) 77/* 78 * XXX: This is somewhat bogus, as we assume here that at most 1024 processes 79 * will hold LOCK_NCHILDREN * 2 locks. We handle failure ok, and we should 80 * probably be safe for the most part, but it's still a SWAG. 81 */ 82#define LOCK_CHILDCOUNT (MAXCPU + 1024) * 2 83 84#define WITNESS_NCHILDREN 6 85 86struct witness_child_list_entry; 87 88struct witness { 89 const char *w_name; 90 struct lock_class *w_class; 91 STAILQ_ENTRY(witness) w_list; /* List of all witnesses. */ 92 STAILQ_ENTRY(witness) w_typelist; /* Witnesses of a type. */ 93 struct witness_child_list_entry *w_children; /* Great evilness... */ 94 const char *w_file; 95 int w_line; 96 u_int w_level; 97 u_int w_refcount; 98 u_char w_Giant_squawked:1; 99 u_char w_other_squawked:1; 100 u_char w_same_squawked:1; 101}; 102 103struct witness_child_list_entry { 104 struct witness_child_list_entry *wcl_next; 105 struct witness *wcl_children[WITNESS_NCHILDREN]; 106 u_int wcl_count; 107}; 108 109STAILQ_HEAD(witness_list, witness); 110 111struct witness_blessed { 112 const char *b_lock1; 113 const char *b_lock2; 114}; 115 116struct witness_order_list_entry { 117 const char *w_name; 118 struct lock_class *w_class; 119}; 120 121static struct witness *enroll(const char *description, 122 struct lock_class *lock_class); 123static int itismychild(struct witness *parent, struct witness *child); 124static void removechild(struct witness *parent, struct witness *child); 125static int isitmychild(struct witness *parent, struct witness *child); 126static int isitmydescendant(struct witness *parent, struct witness *child); 127static int dup_ok(struct witness *); 128static int blessed(struct witness *, struct witness *); 129static void witness_display_list(void(*prnt)(const char *fmt, ...), 130 struct witness_list *list); 131static void witness_displaydescendants(void(*)(const char *fmt, ...), 132 struct witness *); 133static void witness_leveldescendents(struct witness *parent, int level); 134static void witness_levelall(void); 135static struct witness *witness_get(void); 136static void witness_free(struct witness *m); 137static struct witness_child_list_entry *witness_child_get(void); 138static void witness_child_free(struct witness_child_list_entry *wcl); 139static struct lock_list_entry *witness_lock_list_get(void); 140static void witness_lock_list_free(struct lock_list_entry *lle); 141static void witness_display(void(*)(const char *fmt, ...)); 142static struct lock_instance *find_instance(struct lock_list_entry *lock_list, 143 struct lock_object *lock); 144 145MALLOC_DEFINE(M_WITNESS, "witness", "witness structure"); 146 147static int witness_watch = 1; 148TUNABLE_INT("debug.witness_watch", &witness_watch); 149SYSCTL_INT(_debug, OID_AUTO, witness_watch, CTLFLAG_RD, &witness_watch, 0, ""); 150 151#ifdef DDB 152/* 153 * When DDB is enabled and witness_ddb is set to 1, it will cause the system to 154 * drop into kdebug() when: 155 * - a lock heirarchy violation occurs 156 * - locks are held when going to sleep. 157 */ 158#ifdef WITNESS_DDB 159int witness_ddb = 1; 160#else 161int witness_ddb = 0; 162#endif 163TUNABLE_INT("debug.witness_ddb", &witness_ddb); 164SYSCTL_INT(_debug, OID_AUTO, witness_ddb, CTLFLAG_RW, &witness_ddb, 0, ""); 165#endif /* DDB */ 166 167#ifdef WITNESS_SKIPSPIN 168int witness_skipspin = 1; 169#else 170int witness_skipspin = 0; 171#endif 172TUNABLE_INT("debug.witness_skipspin", &witness_skipspin); 173SYSCTL_INT(_debug, OID_AUTO, witness_skipspin, CTLFLAG_RD, &witness_skipspin, 0, 174 ""); 175 176static struct mtx w_mtx; 177static struct witness_list w_free = STAILQ_HEAD_INITIALIZER(w_free); 178static struct witness_list w_all = STAILQ_HEAD_INITIALIZER(w_all); 179static struct witness_list w_spin = STAILQ_HEAD_INITIALIZER(w_spin); 180static struct witness_list w_sleep = STAILQ_HEAD_INITIALIZER(w_sleep); 181static struct witness_child_list_entry *w_child_free = NULL; 182static struct lock_list_entry *w_lock_list_free = NULL; 183static int witness_dead; /* fatal error, probably no memory */ 184 185static struct witness w_data[WITNESS_COUNT]; 186static struct witness_child_list_entry w_childdata[WITNESS_CHILDCOUNT]; 187static struct lock_list_entry w_locklistdata[LOCK_CHILDCOUNT]; 188 189static struct witness_order_list_entry order_lists[] = { 190 { "Giant", &lock_class_mtx_sleep }, 191 { "proctree", &lock_class_sx }, 192 { "allproc", &lock_class_sx }, 193 { "process lock", &lock_class_mtx_sleep }, 194 { "uidinfo hash", &lock_class_mtx_sleep }, 195 { "uidinfo struct", &lock_class_mtx_sleep }, 196 { NULL, NULL }, 197 /* 198 * spin locks 199 */ 200#if defined(__i386__) && defined (SMP) 201 { "com", &lock_class_mtx_spin }, 202#endif 203 { "sio", &lock_class_mtx_spin }, 204#ifdef __i386__ 205 { "cy", &lock_class_mtx_spin }, 206#endif 207 { "ng_node", &lock_class_mtx_spin }, 208 { "ng_worklist", &lock_class_mtx_spin }, 209 { "ithread table lock", &lock_class_mtx_spin }, 210 { "sched lock", &lock_class_mtx_spin }, 211 { "clk", &lock_class_mtx_spin }, 212 { "callout", &lock_class_mtx_spin }, 213 /* 214 * leaf locks 215 */ 216#ifdef SMP 217 { "ap boot", &lock_class_mtx_spin }, 218#ifdef __i386__ 219 { "imen", &lock_class_mtx_spin }, 220#endif 221 { "smp rendezvous", &lock_class_mtx_spin }, 222#endif 223 { NULL, NULL }, 224 { NULL, NULL } 225}; 226 227static const char *dup_list[] = { 228 "process lock", 229 NULL 230}; 231 232/* 233 * Pairs of locks which have been blessed 234 * Don't complain about order problems with blessed locks 235 */ 236static struct witness_blessed blessed_list[] = { 237}; 238static int blessed_count = 239 sizeof(blessed_list) / sizeof(struct witness_blessed); 240 241/* 242 * List of all locks in the system. 243 */ 244STAILQ_HEAD(, lock_object) all_locks = STAILQ_HEAD_INITIALIZER(all_locks); 245 246static struct mtx all_mtx = { 247 { &lock_class_mtx_sleep, /* mtx_object.lo_class */ 248 "All locks list", /* mtx_object.lo_name */ 249 LO_INITIALIZED, /* mtx_object.lo_flags */ 250 { NULL }, /* mtx_object.lo_list */ 251 NULL }, /* mtx_object.lo_witness */ 252 MTX_UNOWNED, 0, /* mtx_lock, mtx_recurse */ 253 0, /* mtx_savecrit */ 254 TAILQ_HEAD_INITIALIZER(all_mtx.mtx_blocked), 255 { NULL, NULL } /* mtx_contested */ 256}; 257 258/* 259 * This global is set to 0 once it becomes safe to use the witness code. 260 */ 261static int witness_cold = 1; 262 263/* 264 * Global variables for book keeping. 265 */ 266static int lock_cur_cnt; 267static int lock_max_cnt; 268 269/* 270 * The WITNESS-enabled diagnostic code. 271 */ 272static void 273witness_initialize(void *dummy __unused) 274{ 275 struct lock_object *lock; 276 struct witness_order_list_entry *order; 277 struct witness *w, *w1; 278 int i; 279 280 /* 281 * We have to release Giant before initializing its witness 282 * structure so that WITNESS doesn't get confused. 283 */ 284 mtx_unlock(&Giant); 285 mtx_assert(&Giant, MA_NOTOWNED); 286 287 STAILQ_INSERT_HEAD(&all_locks, &all_mtx.mtx_object, lo_list); 288 mtx_init(&w_mtx, "witness lock", MTX_SPIN | MTX_QUIET | MTX_NOWITNESS); 289 for (i = 0; i < WITNESS_COUNT; i++) 290 witness_free(&w_data[i]); 291 for (i = 0; i < WITNESS_CHILDCOUNT; i++) 292 witness_child_free(&w_childdata[i]); 293 for (i = 0; i < LOCK_CHILDCOUNT; i++) 294 witness_lock_list_free(&w_locklistdata[i]); 295 296 /* First add in all the specified order lists. */ 297 for (order = order_lists; order->w_name != NULL; order++) { 298 w = enroll(order->w_name, order->w_class); 299 if (w == NULL) 300 continue; 301 w->w_file = "order list"; 302 for (order++; order->w_name != NULL; order++) { 303 w1 = enroll(order->w_name, order->w_class); 304 if (w1 == NULL) 305 continue; 306 w1->w_file = "order list"; 307 itismychild(w, w1); 308 w = w1; 309 } 310 } 311 312 /* Iterate through all locks and add them to witness. */ 313 mtx_lock(&all_mtx); 314 STAILQ_FOREACH(lock, &all_locks, lo_list) { 315 if (lock->lo_flags & LO_WITNESS) 316 lock->lo_witness = enroll(lock->lo_name, 317 lock->lo_class); 318 else 319 lock->lo_witness = NULL; 320 } 321 mtx_unlock(&all_mtx); 322 323 /* Mark the witness code as being ready for use. */ 324 atomic_store_rel_int(&witness_cold, 0); 325 326 mtx_lock(&Giant); 327} 328SYSINIT(witness_init, SI_SUB_WITNESS, SI_ORDER_FIRST, witness_initialize, NULL) 329 330void 331witness_init(struct lock_object *lock) 332{ 333 struct lock_class *class; 334 335 class = lock->lo_class; 336 if (lock->lo_flags & LO_INITIALIZED) 337 panic("%s: lock (%s) %s is already initialized!\n", __func__, 338 class->lc_name, lock->lo_name); 339 340 if ((lock->lo_flags & LO_RECURSABLE) != 0 && 341 (class->lc_flags & LC_RECURSABLE) == 0) 342 panic("%s: lock (%s) %s can not be recursable!\n", __func__, 343 class->lc_name, lock->lo_name); 344 345 if ((lock->lo_flags & LO_SLEEPABLE) != 0 && 346 (class->lc_flags & LC_SLEEPABLE) == 0) 347 panic("%s: lock (%s) %s can not be sleepable!\n", __func__, 348 class->lc_name, lock->lo_name); 349 350 mtx_lock(&all_mtx); 351 STAILQ_INSERT_TAIL(&all_locks, lock, lo_list); 352 lock->lo_flags |= LO_INITIALIZED; 353 lock_cur_cnt++; 354 if (lock_cur_cnt > lock_max_cnt) 355 lock_max_cnt = lock_cur_cnt; 356 mtx_unlock(&all_mtx); 357 if (!witness_cold && !witness_dead && 358 (lock->lo_flags & LO_WITNESS) != 0) 359 lock->lo_witness = enroll(lock->lo_name, class); 360 else 361 lock->lo_witness = NULL; 362} 363 364void 365witness_destroy(struct lock_object *lock) 366{ 367 struct witness *w; 368 369 if (witness_cold) 370 panic("lock (%s) %s destroyed while witness_cold", 371 lock->lo_class->lc_name, lock->lo_name); 372 373 if ((lock->lo_flags & LO_INITIALIZED) == 0) 374 panic("%s: lock (%s) %s is not initialized!\n", __func__, 375 lock->lo_class->lc_name, lock->lo_name); 376 377 /* XXX: need to verify that no one holds the lock */ 378 w = lock->lo_witness; 379 if (w != NULL) { 380 mtx_lock_spin(&w_mtx); 381 w->w_refcount--; 382 if (w->w_refcount == 0) { 383 w->w_name = "(dead)"; 384 w->w_file = "(dead)"; 385 w->w_line = 0; 386 } 387 mtx_unlock_spin(&w_mtx); 388 } 389 390 mtx_lock(&all_mtx); 391 lock_cur_cnt--; 392 STAILQ_REMOVE(&all_locks, lock, lock_object, lo_list); 393 lock->lo_flags &= LO_INITIALIZED; 394 mtx_unlock(&all_mtx); 395} 396 397static void 398witness_display_list(void(*prnt)(const char *fmt, ...), 399 struct witness_list *list) 400{ 401 struct witness *w, *w1; 402 int found; 403 404 STAILQ_FOREACH(w, list, w_typelist) { 405 if (w->w_file == NULL) 406 continue; 407 found = 0; 408 STAILQ_FOREACH(w1, list, w_typelist) { 409 if (isitmychild(w1, w)) { 410 found++; 411 break; 412 } 413 } 414 if (found) 415 continue; 416 /* 417 * This lock has no anscestors, display its descendants. 418 */ 419 witness_displaydescendants(prnt, w); 420 } 421} 422 423static void 424witness_display(void(*prnt)(const char *fmt, ...)) 425{ 426 struct witness *w; 427 428 KASSERT(!witness_cold, ("%s: witness_cold\n", __func__)); 429 witness_levelall(); 430 431 /* 432 * First, handle sleep locks which have been acquired at least 433 * once. 434 */ 435 prnt("Sleep locks:\n"); 436 witness_display_list(prnt, &w_sleep); 437 438 /* 439 * Now do spin locks which have been acquired at least once. 440 */ 441 prnt("\nSpin locks:\n"); 442 witness_display_list(prnt, &w_spin); 443 444 /* 445 * Finally, any locks which have not been acquired yet. 446 */ 447 prnt("\nLocks which were never acquired:\n"); 448 STAILQ_FOREACH(w, &w_all, w_list) { 449 if (w->w_file != NULL) 450 continue; 451 prnt("%s\n", w->w_name); 452 } 453} 454 455void 456witness_lock(struct lock_object *lock, int flags, const char *file, int line) 457{ 458 struct lock_list_entry **lock_list, *lle; 459 struct lock_instance *lock1, *lock2; 460 struct lock_class *class; 461 struct witness *w, *w1; 462 struct proc *p; 463 int i, j; 464#ifdef DDB 465 int go_into_ddb = 0; 466#endif /* DDB */ 467 468 if (witness_cold || witness_dead || lock->lo_witness == NULL || 469 panicstr) 470 return; 471 w = lock->lo_witness; 472 class = lock->lo_class; 473 p = curproc; 474 475 /* 476 * We have to hold a spinlock to keep lock_list valid across the check 477 * in the LC_SLEEPLOCK case. In the LC_SPINLOCK case, it is already 478 * protected by the spinlock we are currently performing the witness 479 * checks on, so it is ok to release the lock after performing this 480 * check. All we have to protect is the LC_SLEEPLOCK case when no 481 * spinlocks are held as we may get preempted during this check and 482 * lock_list could end up pointing to some other CPU's spinlock list. 483 */ 484 mtx_lock_spin(&w_mtx); 485 lock_list = PCPU_PTR(spinlocks); 486 if (class->lc_flags & LC_SLEEPLOCK) { 487 if (*lock_list != NULL && (flags & LOP_TRYLOCK) == 0) { 488 mtx_unlock_spin(&w_mtx); 489 panic("blockable sleep lock (%s) %s @ %s:%d", 490 class->lc_name, lock->lo_name, file, line); 491 } 492 lock_list = &p->p_sleeplocks; 493 } 494 mtx_unlock_spin(&w_mtx); 495 496 /* 497 * Try locks do not block if they fail to acquire the lock, thus 498 * there is no danger of deadlocks or of switching while holding a 499 * spin lock if we acquire a lock via a try operation. 500 */ 501 if (flags & LOP_TRYLOCK) 502 goto out; 503 504 /* 505 * Is this the first lock acquired? If so, then no order checking 506 * is needed. 507 */ 508 if (*lock_list == NULL) 509 goto out; 510 511 /* 512 * Check to see if we are recursing on a lock we already own. 513 */ 514 lock1 = find_instance(*lock_list, lock); 515 if (lock1 != NULL) { 516 if ((lock1->li_flags & LI_EXCLUSIVE) != 0 && 517 (flags & LOP_EXCLUSIVE) == 0) { 518 printf("shared lock of (%s) %s @ %s:%d\n", 519 class->lc_name, lock->lo_name, file, line); 520 printf("while exclusively locked from %s:%d\n", 521 lock1->li_file, lock1->li_line); 522 panic("share->excl"); 523 } 524 if ((lock1->li_flags & LI_EXCLUSIVE) == 0 && 525 (flags & LOP_EXCLUSIVE) != 0) { 526 printf("exclusive lock of (%s) %s @ %s:%d\n", 527 class->lc_name, lock->lo_name, file, line); 528 printf("while share locked from %s:%d\n", 529 lock1->li_file, lock1->li_line); 530 panic("excl->share"); 531 } 532 lock1->li_flags++; 533 if ((lock->lo_flags & LO_RECURSABLE) == 0) { 534 printf( 535 "recursed on non-recursive lock (%s) %s @ %s:%d\n", 536 class->lc_name, lock->lo_name, file, line); 537 printf("first acquired @ %s:%d\n", lock1->li_file, 538 lock1->li_line); 539 panic("recurse"); 540 } 541 lock1->li_file = file; 542 lock1->li_line = line; 543 return; 544 } 545 546 /* 547 * Check for duplicate locks of the same type. Note that we only 548 * have to check for this on the last lock we just acquired. Any 549 * other cases will be caught as lock order violations. 550 */ 551 lock1 = &(*lock_list)->ll_children[(*lock_list)->ll_count - 1]; 552 w1 = lock1->li_lock->lo_witness; 553 if (w1 == w) { 554 if (w->w_same_squawked || dup_ok(w)) 555 goto out; 556 w->w_same_squawked = 1; 557 printf("acquiring duplicate lock of same type: \"%s\"\n", 558 lock->lo_name); 559 printf(" 1st @ %s:%d\n", lock1->li_file, lock1->li_line); 560 printf(" 2nd @ %s:%d\n", file, line); 561#ifdef DDB 562 go_into_ddb = 1; 563#endif /* DDB */ 564 goto out; 565 } 566 MPASS(!mtx_owned(&w_mtx)); 567 mtx_lock_spin(&w_mtx); 568 /* 569 * If we have a known higher number just say ok 570 */ 571 if (witness_watch > 1 && w->w_level > w1->w_level) { 572 mtx_unlock_spin(&w_mtx); 573 goto out; 574 } 575 if (isitmydescendant(w1, w)) { 576 mtx_unlock_spin(&w_mtx); 577 goto out; 578 } 579 for (j = 0, lle = *lock_list; lle != NULL; lle = lle->ll_next) { 580 for (i = lle->ll_count - 1; i >= 0; i--, j++) { 581 582 MPASS(j < WITNESS_COUNT); 583 lock1 = &lle->ll_children[i]; 584 w1 = lock1->li_lock->lo_witness; 585 586 /* 587 * If this lock doesn't undergo witness checking, 588 * then skip it. 589 */ 590 if (w1 == NULL) { 591 KASSERT((lock1->li_lock->lo_flags & LO_WITNESS) == 0, 592 ("lock missing witness structure")); 593 continue; 594 } 595 /* 596 * If we are locking Giant and we slept with this 597 * lock, then skip it. 598 */ 599 if ((lock1->li_flags & LI_SLEPT) != 0 && 600 lock == &Giant.mtx_object) 601 continue; 602 if (!isitmydescendant(w, w1)) 603 continue; 604 /* 605 * We have a lock order violation, check to see if it 606 * is allowed or has already been yelled about. 607 */ 608 mtx_unlock_spin(&w_mtx); 609 if (blessed(w, w1)) 610 goto out; 611 if (lock1->li_lock == &Giant.mtx_object) { 612 if (w1->w_Giant_squawked) 613 goto out; 614 else 615 w1->w_Giant_squawked = 1; 616 } else { 617 if (w1->w_other_squawked) 618 goto out; 619 else 620 w1->w_other_squawked = 1; 621 } 622 /* 623 * Ok, yell about it. 624 */ 625 printf("lock order reversal\n"); 626 /* 627 * Try to locate an earlier lock with 628 * witness w in our list. 629 */ 630 do { 631 lock2 = &lle->ll_children[i]; 632 MPASS(lock2->li_lock != NULL); 633 if (lock2->li_lock->lo_witness == w) 634 break; 635 i--; 636 if (i == 0 && lle->ll_next != NULL) { 637 lle = lle->ll_next; 638 i = lle->ll_count - 1; 639 MPASS(i != 0); 640 } 641 } while (i >= 0); 642 if (i < 0) { 643 printf(" 1st %p %s @ %s:%d\n", lock1->li_lock, 644 lock1->li_lock->lo_name, lock1->li_file, 645 lock1->li_line); 646 printf(" 2nd %p %s @ %s:%d\n", lock, 647 lock->lo_name, file, line); 648 } else { 649 printf(" 1st %p %s @ %s:%d\n", lock2->li_lock, 650 lock2->li_lock->lo_name, lock2->li_file, 651 lock2->li_line); 652 printf(" 2nd %p %s @ %s:%d\n", lock1->li_lock, 653 lock1->li_lock->lo_name, lock1->li_file, 654 lock1->li_line); 655 printf(" 3rd %p %s @ %s:%d\n", lock, 656 lock->lo_name, file, line); 657 } 658#ifdef DDB 659 go_into_ddb = 1; 660#endif /* DDB */ 661 goto out; 662 } 663 } 664 lock1 = &(*lock_list)->ll_children[(*lock_list)->ll_count - 1]; 665 if (!itismychild(lock1->li_lock->lo_witness, w)) 666 mtx_unlock_spin(&w_mtx); 667 668out: 669#ifdef DDB 670 if (witness_ddb && go_into_ddb) 671 Debugger(__func__); 672#endif /* DDB */ 673 w->w_file = file; 674 w->w_line = line; 675 676 lle = *lock_list; 677 if (lle == NULL || lle->ll_count == LOCK_NCHILDREN) { 678 *lock_list = witness_lock_list_get(); 679 if (*lock_list == NULL) 680 return; 681 (*lock_list)->ll_next = lle; 682 lle = *lock_list; 683 } 684 lock1 = &lle->ll_children[lle->ll_count++]; 685 lock1->li_lock = lock; 686 lock1->li_line = line; 687 lock1->li_file = file; 688 if ((flags & LOP_EXCLUSIVE) != 0) 689 lock1->li_flags = LI_EXCLUSIVE; 690 else 691 lock1->li_flags = 0; 692} 693 694void 695witness_unlock(struct lock_object *lock, int flags, const char *file, int line) 696{ 697 struct lock_list_entry **lock_list, *lle; 698 struct lock_instance *instance; 699 struct lock_class *class; 700 struct proc *p; 701 int i, j; 702 703 if (witness_cold || witness_dead || lock->lo_witness == NULL || 704 panicstr) 705 return; 706 p = curproc; 707 class = lock->lo_class; 708 if (class->lc_flags & LC_SLEEPLOCK) 709 lock_list = &p->p_sleeplocks; 710 else 711 lock_list = PCPU_PTR(spinlocks); 712 for (; *lock_list != NULL; lock_list = &(*lock_list)->ll_next) 713 for (i = 0; i < (*lock_list)->ll_count; i++) { 714 instance = &(*lock_list)->ll_children[i]; 715 if (instance->li_lock == lock) { 716 if ((instance->li_flags & LI_EXCLUSIVE) != 0 && 717 (flags & LOP_EXCLUSIVE) == 0) { 718 printf( 719 "shared unlock of (%s) %s @ %s:%d\n", 720 class->lc_name, lock->lo_name, 721 file, line); 722 printf( 723 "while exclusively locked from %s:%d\n", 724 instance->li_file, 725 instance->li_line); 726 panic("excl->ushare"); 727 } 728 if ((instance->li_flags & LI_EXCLUSIVE) == 0 && 729 (flags & LOP_EXCLUSIVE) != 0) { 730 printf( 731 "exclusive unlock of (%s) %s @ %s:%d\n", 732 class->lc_name, lock->lo_name, 733 file, line); 734 printf( 735 "while share locked from %s:%d\n", 736 instance->li_file, 737 instance->li_line); 738 panic("share->uexcl"); 739 } 740 /* If we are recursed, unrecurse. */ 741 if ((instance->li_flags & LI_RECURSEMASK) > 0) { 742 instance->li_flags--; 743 goto out; 744 } 745 (*lock_list)->ll_count--; 746 for (j = i; j < (*lock_list)->ll_count; j++) 747 (*lock_list)->ll_children[j] = 748 (*lock_list)->ll_children[j + 1]; 749 if ((*lock_list)->ll_count == 0) { 750 lle = *lock_list; 751 *lock_list = lle->ll_next; 752 witness_lock_list_free(lle); 753 } 754 goto out; 755 } 756 } 757 panic("lock (%s) %s not locked @ %s:%d", class->lc_name, lock->lo_name, 758 file, line); 759out: 760 /* 761 * We don't need to protect this PCPU_GET() here against preemption 762 * because if we hold any spinlocks then we are already protected, 763 * and if we don't we will get NULL if we hold no spinlocks even if 764 * we switch CPU's while reading it. 765 */ 766 if (class->lc_flags & LC_SLEEPLOCK) { 767 if ((flags & LOP_NOSWITCH) == 0 && PCPU_GET(spinlocks) != NULL) 768 panic("switchable sleep unlock (%s) %s @ %s:%d", 769 class->lc_name, lock->lo_name, file, line); 770 } 771} 772 773/* 774 * Warn if any held locks are not sleepable. Note that Giant and the lock 775 * passed in are both special cases since they are both released during the 776 * sleep process and aren't actually held while the process is asleep. 777 */ 778int 779witness_sleep(int check_only, struct lock_object *lock, const char *file, 780 int line) 781{ 782 struct lock_list_entry **lock_list, *lle; 783 struct lock_instance *lock1; 784 struct proc *p; 785 critical_t savecrit; 786 int i, n; 787 788 if (witness_dead || panicstr) 789 return (0); 790 KASSERT(!witness_cold, ("%s: witness_cold\n", __func__)); 791 n = 0; 792 /* 793 * Preemption bad because we need PCPU_PTR(spinlocks) to not change. 794 */ 795 savecrit = critical_enter(); 796 p = curproc; 797 lock_list = &p->p_sleeplocks; 798again: 799 for (lle = *lock_list; lle != NULL; lle = lle->ll_next) 800 for (i = lle->ll_count - 1; i >= 0; i--) { 801 lock1 = &lle->ll_children[i]; 802 if (lock1->li_lock == lock || 803 lock1->li_lock == &Giant.mtx_object) 804 continue; 805 if ((lock1->li_lock->lo_flags & LO_SLEEPABLE) != 0) { 806 if (check_only == 0) 807 lock1->li_flags |= LI_SLEPT; 808 continue; 809 } 810 n++; 811 printf("%s:%d: %s with \"%s\" locked from %s:%d\n", 812 file, line, check_only ? "could sleep" : "sleeping", 813 lock1->li_lock->lo_name, lock1->li_file, 814 lock1->li_line); 815 } 816 if (lock_list == &p->p_sleeplocks) { 817 lock_list = PCPU_PTR(spinlocks); 818 goto again; 819 } 820#ifdef DDB 821 if (witness_ddb && n) 822 Debugger(__func__); 823#endif /* DDB */ 824 critical_exit(savecrit); 825 return (n); 826} 827 828static struct witness * 829enroll(const char *description, struct lock_class *lock_class) 830{ 831 struct witness *w; 832 833 if (!witness_watch || witness_dead) 834 return (NULL); 835 836 if ((lock_class->lc_flags & LC_SPINLOCK) && witness_skipspin) 837 return (NULL); 838 mtx_lock_spin(&w_mtx); 839 STAILQ_FOREACH(w, &w_all, w_list) { 840 if (strcmp(description, w->w_name) == 0) { 841 w->w_refcount++; 842 mtx_unlock_spin(&w_mtx); 843 if (lock_class != w->w_class) 844 panic( 845 "lock (%s) %s does not match earlier (%s) lock", 846 description, lock_class->lc_name, 847 w->w_class->lc_name); 848 return (w); 849 } 850 } 851 /* 852 * This isn't quite right, as witness_cold is still 0 while we 853 * enroll all the locks initialized before witness_initialize(). 854 */ 855 if ((lock_class->lc_flags & LC_SPINLOCK) && !witness_cold) { 856 mtx_unlock_spin(&w_mtx); 857 panic("spin lock %s not in order list", description); 858 } 859 if ((w = witness_get()) == NULL) 860 return (NULL); 861 w->w_name = description; 862 w->w_class = lock_class; 863 w->w_refcount = 1; 864 STAILQ_INSERT_HEAD(&w_all, w, w_list); 865 if (lock_class->lc_flags & LC_SPINLOCK) 866 STAILQ_INSERT_HEAD(&w_spin, w, w_typelist); 867 else if (lock_class->lc_flags & LC_SLEEPLOCK) 868 STAILQ_INSERT_HEAD(&w_sleep, w, w_typelist); 869 else { 870 mtx_unlock_spin(&w_mtx); 871 panic("lock class %s is not sleep or spin", 872 lock_class->lc_name); 873 } 874 mtx_unlock_spin(&w_mtx); 875 876 return (w); 877} 878 879static int 880itismychild(struct witness *parent, struct witness *child) 881{ 882 static int recursed; 883 struct witness_child_list_entry **wcl; 884 struct witness_list *list; 885 886 MPASS(child != NULL && parent != NULL); 887 if ((parent->w_class->lc_flags & (LC_SLEEPLOCK | LC_SPINLOCK)) != 888 (child->w_class->lc_flags & (LC_SLEEPLOCK | LC_SPINLOCK))) 889 panic( 890 "%s: parent (%s) and child (%s) are not the same lock type", 891 __func__, parent->w_class->lc_name, 892 child->w_class->lc_name); 893 894 /* 895 * Insert "child" after "parent" 896 */ 897 wcl = &parent->w_children; 898 while (*wcl != NULL && (*wcl)->wcl_count == WITNESS_NCHILDREN) 899 wcl = &(*wcl)->wcl_next; 900 901 if (*wcl == NULL) { 902 *wcl = witness_child_get(); 903 if (*wcl == NULL) 904 return (1); 905 } 906 907 (*wcl)->wcl_children[(*wcl)->wcl_count++] = child; 908 909 /* 910 * Now prune whole tree. We look for cases where a lock is now 911 * both a descendant and a direct child of a given lock. In that 912 * case, we want to remove the direct child link from the tree. 913 */ 914 if (recursed) 915 return (0); 916 recursed = 1; 917 if (parent->w_class->lc_flags & LC_SLEEPLOCK) 918 list = &w_sleep; 919 else 920 list = &w_spin; 921 STAILQ_FOREACH(child, list, w_typelist) { 922 STAILQ_FOREACH(parent, list, w_typelist) { 923 if (!isitmychild(parent, child)) 924 continue; 925 removechild(parent, child); 926 if (isitmydescendant(parent, child)) 927 continue; 928 itismychild(parent, child); 929 } 930 } 931 recursed = 0; 932 witness_levelall(); 933 return (0); 934} 935 936static void 937removechild(struct witness *parent, struct witness *child) 938{ 939 struct witness_child_list_entry **wcl, *wcl1; 940 int i; 941 942 for (wcl = &parent->w_children; *wcl != NULL; wcl = &(*wcl)->wcl_next) 943 for (i = 0; i < (*wcl)->wcl_count; i++) 944 if ((*wcl)->wcl_children[i] == child) 945 goto found; 946 return; 947found: 948 (*wcl)->wcl_count--; 949 if ((*wcl)->wcl_count > i) 950 (*wcl)->wcl_children[i] = 951 (*wcl)->wcl_children[(*wcl)->wcl_count]; 952 MPASS((*wcl)->wcl_children[i] != NULL); 953 954 if ((*wcl)->wcl_count != 0) 955 return; 956 957 wcl1 = *wcl; 958 *wcl = wcl1->wcl_next; 959 witness_child_free(wcl1); 960} 961 962static int 963isitmychild(struct witness *parent, struct witness *child) 964{ 965 struct witness_child_list_entry *wcl; 966 int i; 967 968 for (wcl = parent->w_children; wcl != NULL; wcl = wcl->wcl_next) { 969 for (i = 0; i < wcl->wcl_count; i++) { 970 if (wcl->wcl_children[i] == child) 971 return (1); 972 } 973 } 974 return (0); 975} 976 977static int 978isitmydescendant(struct witness *parent, struct witness *child) 979{ 980 struct witness_child_list_entry *wcl; 981 int i, j; 982 983 if (isitmychild(parent, child)) 984 return (1); 985 j = 0; 986 for (wcl = parent->w_children; wcl != NULL; wcl = wcl->wcl_next) { 987 MPASS(j < 1000); 988 for (i = 0; i < wcl->wcl_count; i++) { 989 if (isitmydescendant(wcl->wcl_children[i], child)) 990 return (1); 991 } 992 j++; 993 } 994 return (0); 995} 996 997void 998witness_levelall (void) 999{ 1000 struct witness_list *list; 1001 struct witness *w, *w1; 1002 1003 /* 1004 * First clear all levels. 1005 */ 1006 STAILQ_FOREACH(w, &w_all, w_list) { 1007 w->w_level = 0; 1008 } 1009 1010 /* 1011 * Look for locks with no parent and level all their descendants. 1012 */ 1013 STAILQ_FOREACH(w, &w_all, w_list) { 1014 /* 1015 * This is just an optimization, technically we could get 1016 * away just walking the all list each time. 1017 */ 1018 if (w->w_class->lc_flags & LC_SLEEPLOCK) 1019 list = &w_sleep; 1020 else 1021 list = &w_spin; 1022 STAILQ_FOREACH(w1, list, w_typelist) { 1023 if (isitmychild(w1, w)) 1024 goto skip; 1025 } 1026 witness_leveldescendents(w, 0); 1027 skip: 1028 } 1029} 1030 1031static void 1032witness_leveldescendents(struct witness *parent, int level) 1033{ 1034 struct witness_child_list_entry *wcl; 1035 int i; 1036 1037 if (parent->w_level < level) 1038 parent->w_level = level; 1039 level++; 1040 for (wcl = parent->w_children; wcl != NULL; wcl = wcl->wcl_next) 1041 for (i = 0; i < wcl->wcl_count; i++) 1042 witness_leveldescendents(wcl->wcl_children[i], level); 1043} 1044 1045static void 1046witness_displaydescendants(void(*prnt)(const char *fmt, ...), 1047 struct witness *parent) 1048{ 1049 struct witness_child_list_entry *wcl; 1050 int i, level; 1051 1052 level = parent->w_level; 1053 1054 prnt("%-2d", level); 1055 for (i = 0; i < level; i++) 1056 prnt(" "); 1057 prnt("%s", parent->w_name); 1058 if (parent->w_file != NULL) 1059 prnt(" -- last acquired @ %s:%d\n", parent->w_file, 1060 parent->w_line); 1061 1062 for (wcl = parent->w_children; wcl != NULL; wcl = wcl->wcl_next) 1063 for (i = 0; i < wcl->wcl_count; i++) 1064 witness_displaydescendants(prnt, 1065 wcl->wcl_children[i]); 1066} 1067 1068static int 1069dup_ok(struct witness *w) 1070{ 1071 const char **dup; 1072 1073 for (dup = dup_list; *dup != NULL; dup++) 1074 if (strcmp(w->w_name, *dup) == 0) 1075 return (1); 1076 return (0); 1077} 1078 1079static int 1080blessed(struct witness *w1, struct witness *w2) 1081{ 1082 int i; 1083 struct witness_blessed *b; 1084 1085 for (i = 0; i < blessed_count; i++) { 1086 b = &blessed_list[i]; 1087 if (strcmp(w1->w_name, b->b_lock1) == 0) { 1088 if (strcmp(w2->w_name, b->b_lock2) == 0) 1089 return (1); 1090 continue; 1091 } 1092 if (strcmp(w1->w_name, b->b_lock2) == 0) 1093 if (strcmp(w2->w_name, b->b_lock1) == 0) 1094 return (1); 1095 } 1096 return (0); 1097} 1098 1099static struct witness * 1100witness_get(void) 1101{ 1102 struct witness *w; 1103 1104 if (witness_dead) { 1105 mtx_unlock_spin(&w_mtx); 1106 return (NULL); 1107 } 1108 if (STAILQ_EMPTY(&w_free)) { 1109 witness_dead = 1; 1110 mtx_unlock_spin(&w_mtx); 1111 printf("%s: witness exhausted\n", __func__); 1112 return (NULL); 1113 } 1114 w = STAILQ_FIRST(&w_free); 1115 STAILQ_REMOVE_HEAD(&w_free, w_list); 1116 bzero(w, sizeof(*w)); 1117 return (w); 1118} 1119 1120static void 1121witness_free(struct witness *w) 1122{ 1123 1124 STAILQ_INSERT_HEAD(&w_free, w, w_list); 1125} 1126 1127static struct witness_child_list_entry * 1128witness_child_get(void) 1129{ 1130 struct witness_child_list_entry *wcl; 1131 1132 if (witness_dead) { 1133 mtx_unlock_spin(&w_mtx); 1134 return (NULL); 1135 } 1136 wcl = w_child_free; 1137 if (wcl == NULL) { 1138 witness_dead = 1; 1139 mtx_unlock_spin(&w_mtx); 1140 printf("%s: witness exhausted\n", __func__); 1141 return (NULL); 1142 } 1143 w_child_free = wcl->wcl_next; 1144 bzero(wcl, sizeof(*wcl)); 1145 return (wcl); 1146} 1147 1148static void 1149witness_child_free(struct witness_child_list_entry *wcl) 1150{ 1151 1152 wcl->wcl_next = w_child_free; 1153 w_child_free = wcl; 1154} 1155 1156static struct lock_list_entry * 1157witness_lock_list_get(void) 1158{ 1159 struct lock_list_entry *lle; 1160 1161 if (witness_dead) 1162 return (NULL); 1163 mtx_lock_spin(&w_mtx); 1164 lle = w_lock_list_free; 1165 if (lle == NULL) { 1166 witness_dead = 1; 1167 mtx_unlock_spin(&w_mtx); 1168 printf("%s: witness exhausted\n", __func__); 1169 return (NULL); 1170 } 1171 w_lock_list_free = lle->ll_next; 1172 mtx_unlock_spin(&w_mtx); 1173 bzero(lle, sizeof(*lle)); 1174 return (lle); 1175} 1176 1177static void 1178witness_lock_list_free(struct lock_list_entry *lle) 1179{ 1180 1181 mtx_lock_spin(&w_mtx); 1182 lle->ll_next = w_lock_list_free; 1183 w_lock_list_free = lle; 1184 mtx_unlock_spin(&w_mtx); 1185} 1186 1187static struct lock_instance * 1188find_instance(struct lock_list_entry *lock_list, struct lock_object *lock) 1189{ 1190 struct lock_list_entry *lle; 1191 struct lock_instance *instance; 1192 int i; 1193 1194 for (lle = lock_list; lle != NULL; lle = lle->ll_next) 1195 for (i = lle->ll_count - 1; i >= 0; i--) { 1196 instance = &lle->ll_children[i]; 1197 if (instance->li_lock == lock) 1198 return (instance); 1199 } 1200 return (NULL); 1201} 1202 1203int 1204witness_list_locks(struct lock_list_entry **lock_list) 1205{ 1206 struct lock_list_entry *lle; 1207 struct lock_instance *instance; 1208 struct lock_object *lock; 1209 int i, nheld; 1210 1211 nheld = 0; 1212 for (lle = *lock_list; lle != NULL; lle = lle->ll_next) 1213 for (i = lle->ll_count - 1; i >= 0; i--) { 1214 instance = &lle->ll_children[i]; 1215 lock = instance->li_lock; 1216 printf("%s (%s) %s (%p) locked @ %s:%d\n", 1217 (instance->li_flags & LI_EXCLUSIVE) != 0 ? 1218 "exclusive" : "shared", 1219 lock->lo_class->lc_name, lock->lo_name, lock, 1220 instance->li_file, instance->li_line); 1221 nheld++; 1222 } 1223 return (nheld); 1224} 1225 1226/* 1227 * Calling this on p != curproc is bad unless we are in ddb. 1228 */ 1229int 1230witness_list(struct proc *p) 1231{ 1232 critical_t savecrit; 1233 int nheld; 1234 1235 KASSERT(p == curproc || db_active, 1236 ("%s: p != curproc and we aren't in the debugger", __func__)); 1237 KASSERT(!witness_cold, ("%s: witness_cold", __func__)); 1238 1239 if (!db_active && witness_dead) 1240 return (0); 1241 1242 nheld = witness_list_locks(&p->p_sleeplocks); 1243 1244 /* 1245 * We only handle spinlocks if p == curproc. This is somewhat broken 1246 * if p is currently executing on some other CPU and holds spin locks 1247 * as we won't display those locks. If we had a MI way of getting 1248 * the per-cpu data for a given cpu then we could use p->p_oncpu to 1249 * get the list of spinlocks for this process and "fix" this. 1250 */ 1251 if (p == curproc) { 1252 /* 1253 * Preemption bad because we need PCPU_PTR(spinlocks) to not 1254 * change. 1255 */ 1256 savecrit = critical_enter(); 1257 nheld += witness_list_locks(PCPU_PTR(spinlocks)); 1258 critical_exit(savecrit); 1259 } 1260 1261 return (nheld); 1262} 1263 1264void 1265witness_save(struct lock_object *lock, const char **filep, int *linep) 1266{ 1267 struct lock_instance *instance; 1268 1269 KASSERT(!witness_cold, ("%s: witness_cold\n", __func__)); 1270 if (lock->lo_witness == NULL || witness_dead) 1271 return; 1272 1273 KASSERT(lock->lo_class->lc_flags & LC_SLEEPLOCK, 1274 ("%s: lock (%s) %s is not a sleep lock", __func__, 1275 lock->lo_class->lc_name, lock->lo_name)); 1276 instance = find_instance(curproc->p_sleeplocks, lock); 1277 KASSERT(instance != NULL, ("%s: lock (%s) %s not locked", __func__, 1278 lock->lo_class->lc_name, lock->lo_name)); 1279 1280 *filep = instance->li_file; 1281 *linep = instance->li_line; 1282} 1283 1284void 1285witness_restore(struct lock_object *lock, const char *file, int line) 1286{ 1287 struct lock_instance *instance; 1288 1289 KASSERT(!witness_cold, ("%s: witness_cold\n", __func__)); 1290 if (lock->lo_witness == NULL || witness_dead) 1291 return; 1292 1293 KASSERT(lock->lo_class->lc_flags & LC_SLEEPLOCK, 1294 ("%s: lock (%s) %s is not a sleep lock", __func__, 1295 lock->lo_class->lc_name, lock->lo_name)); 1296 instance = find_instance(curproc->p_sleeplocks, lock); 1297 KASSERT(instance != NULL, ("%s: lock (%s) %s not locked", __func__, 1298 lock->lo_class->lc_name, lock->lo_name)); 1299 1300 lock->lo_witness->w_file = file; 1301 lock->lo_witness->w_line = line; 1302 instance->li_file = file; 1303 instance->li_line = line; 1304} 1305 1306#ifdef DDB 1307 1308DB_SHOW_COMMAND(locks, db_witness_list) 1309{ 1310 struct proc *p; 1311 pid_t pid; 1312 1313 if (have_addr) { 1314 pid = (addr % 16) + ((addr >> 4) % 16) * 10 + 1315 ((addr >> 8) % 16) * 100 + ((addr >> 12) % 16) * 1000 + 1316 ((addr >> 16) % 16) * 10000; 1317 1318 /* sx_slock(&allproc_lock); */ 1319 LIST_FOREACH(p, &allproc, p_list) { 1320 if (p->p_pid == pid) 1321 break; 1322 } 1323 /* sx_sunlock(&allproc_lock); */ 1324 if (p == NULL) { 1325 db_printf("pid %d not found\n", pid); 1326 return; 1327 } 1328 } else 1329 p = curproc; 1330 1331 witness_list(p); 1332} 1333 1334DB_SHOW_COMMAND(witness, db_witness_display) 1335{ 1336 1337 witness_display(db_printf); 1338} 1339#endif 1340