subr_witness.c revision 78785
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 78785 2001-06-25 23:17:52Z jhb $ 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 { "callout", &lock_class_mtx_spin }, 212 /* 213 * leaf locks 214 */ 215#ifdef SMP 216 { "ap boot", &lock_class_mtx_spin }, 217#ifdef __i386__ 218 { "imen", &lock_class_mtx_spin }, 219#endif 220 { "smp rendezvous", &lock_class_mtx_spin }, 221#endif 222 { "clk", &lock_class_mtx_spin }, 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 CTR1(KTR_WITNESS, "%s: initializing witness", __func__); 288 STAILQ_INSERT_HEAD(&all_locks, &all_mtx.mtx_object, lo_list); 289 mtx_init(&w_mtx, "witness lock", MTX_SPIN | MTX_QUIET | MTX_NOWITNESS); 290 for (i = 0; i < WITNESS_COUNT; i++) 291 witness_free(&w_data[i]); 292 for (i = 0; i < WITNESS_CHILDCOUNT; i++) 293 witness_child_free(&w_childdata[i]); 294 for (i = 0; i < LOCK_CHILDCOUNT; i++) 295 witness_lock_list_free(&w_locklistdata[i]); 296 297 /* First add in all the specified order lists. */ 298 for (order = order_lists; order->w_name != NULL; order++) { 299 w = enroll(order->w_name, order->w_class); 300 if (w == NULL) 301 continue; 302 w->w_file = "order list"; 303 for (order++; order->w_name != NULL; order++) { 304 w1 = enroll(order->w_name, order->w_class); 305 if (w1 == NULL) 306 continue; 307 w1->w_file = "order list"; 308 itismychild(w, w1); 309 w = w1; 310 } 311 } 312 313 /* Iterate through all locks and add them to witness. */ 314 mtx_lock(&all_mtx); 315 STAILQ_FOREACH(lock, &all_locks, lo_list) { 316 if (lock->lo_flags & LO_WITNESS) 317 lock->lo_witness = enroll(lock->lo_name, 318 lock->lo_class); 319 else 320 lock->lo_witness = NULL; 321 } 322 mtx_unlock(&all_mtx); 323 324 /* Mark the witness code as being ready for use. */ 325 atomic_store_rel_int(&witness_cold, 0); 326 327 mtx_lock(&Giant); 328} 329SYSINIT(witness_init, SI_SUB_WITNESS, SI_ORDER_FIRST, witness_initialize, NULL) 330 331void 332witness_init(struct lock_object *lock) 333{ 334 struct lock_class *class; 335 336 class = lock->lo_class; 337 if (lock->lo_flags & LO_INITIALIZED) 338 panic("%s: lock (%s) %s is already initialized!\n", __func__, 339 class->lc_name, lock->lo_name); 340 341 if ((lock->lo_flags & LO_RECURSABLE) != 0 && 342 (class->lc_flags & LC_RECURSABLE) == 0) 343 panic("%s: lock (%s) %s can not be recursable!\n", __func__, 344 class->lc_name, lock->lo_name); 345 346 if ((lock->lo_flags & LO_SLEEPABLE) != 0 && 347 (class->lc_flags & LC_SLEEPABLE) == 0) 348 panic("%s: lock (%s) %s can not be sleepable!\n", __func__, 349 class->lc_name, lock->lo_name); 350 351 mtx_lock(&all_mtx); 352 STAILQ_INSERT_TAIL(&all_locks, lock, lo_list); 353 lock->lo_flags |= LO_INITIALIZED; 354 lock_cur_cnt++; 355 if (lock_cur_cnt > lock_max_cnt) 356 lock_max_cnt = lock_cur_cnt; 357 mtx_unlock(&all_mtx); 358 if (!witness_cold && !witness_dead && 359 (lock->lo_flags & LO_WITNESS) != 0) 360 lock->lo_witness = enroll(lock->lo_name, class); 361 else 362 lock->lo_witness = NULL; 363} 364 365void 366witness_destroy(struct lock_object *lock) 367{ 368 struct witness *w; 369 370 if (witness_cold) 371 panic("lock (%s) %s destroyed while witness_cold", 372 lock->lo_class->lc_name, lock->lo_name); 373 374 if ((lock->lo_flags & LO_INITIALIZED) == 0) 375 panic("%s: lock (%s) %s is not initialized!\n", __func__, 376 lock->lo_class->lc_name, lock->lo_name); 377 378 /* XXX: need to verify that no one holds the lock */ 379 w = lock->lo_witness; 380 if (w != NULL) { 381 mtx_lock_spin(&w_mtx); 382 w->w_refcount--; 383 if (w->w_refcount == 0) { 384 CTR1(KTR_WITNESS, "Marking witness %s as dead", 385 w->w_name); 386 w->w_name = "(dead)"; 387 w->w_file = "(dead)"; 388 w->w_line = 0; 389 } 390 mtx_unlock_spin(&w_mtx); 391 } 392 393 mtx_lock(&all_mtx); 394 lock_cur_cnt--; 395 STAILQ_REMOVE(&all_locks, lock, lock_object, lo_list); 396 lock->lo_flags &= LO_INITIALIZED; 397 mtx_unlock(&all_mtx); 398} 399 400static void 401witness_display_list(void(*prnt)(const char *fmt, ...), 402 struct witness_list *list) 403{ 404 struct witness *w, *w1; 405 int found; 406 407 STAILQ_FOREACH(w, list, w_typelist) { 408 if (w->w_file == NULL) 409 continue; 410 found = 0; 411 STAILQ_FOREACH(w1, list, w_typelist) { 412 if (isitmychild(w1, w)) { 413 found++; 414 break; 415 } 416 } 417 if (found) 418 continue; 419 /* 420 * This lock has no anscestors, display its descendants. 421 */ 422 witness_displaydescendants(prnt, w); 423 } 424} 425 426static void 427witness_display(void(*prnt)(const char *fmt, ...)) 428{ 429 struct witness *w; 430 431 KASSERT(!witness_cold, ("%s: witness_cold\n", __func__)); 432 witness_levelall(); 433 434 /* 435 * First, handle sleep locks which have been acquired at least 436 * once. 437 */ 438 prnt("Sleep locks:\n"); 439 witness_display_list(prnt, &w_sleep); 440 441 /* 442 * Now do spin locks which have been acquired at least once. 443 */ 444 prnt("\nSpin locks:\n"); 445 witness_display_list(prnt, &w_spin); 446 447 /* 448 * Finally, any locks which have not been acquired yet. 449 */ 450 prnt("\nLocks which were never acquired:\n"); 451 STAILQ_FOREACH(w, &w_all, w_list) { 452 if (w->w_file != NULL) 453 continue; 454 prnt("%s\n", w->w_name); 455 } 456} 457 458void 459witness_lock(struct lock_object *lock, int flags, const char *file, int line) 460{ 461 struct lock_list_entry **lock_list, *lle; 462 struct lock_instance *lock1, *lock2; 463 struct lock_class *class; 464 struct witness *w, *w1; 465 struct proc *p; 466 int i, j; 467#ifdef DDB 468 int go_into_ddb = 0; 469#endif /* DDB */ 470 471 if (witness_cold || witness_dead || lock->lo_witness == NULL || 472 panicstr) 473 return; 474 w = lock->lo_witness; 475 class = lock->lo_class; 476 p = curproc; 477 478 /* 479 * We have to hold a spinlock to keep lock_list valid across the check 480 * in the LC_SLEEPLOCK case. In the LC_SPINLOCK case, it is already 481 * protected by the spinlock we are currently performing the witness 482 * checks on, so it is ok to release the lock after performing this 483 * check. All we have to protect is the LC_SLEEPLOCK case when no 484 * spinlocks are held as we may get preempted during this check and 485 * lock_list could end up pointing to some other CPU's spinlock list. 486 */ 487 mtx_lock_spin(&w_mtx); 488 lock_list = PCPU_PTR(spinlocks); 489 if (class->lc_flags & LC_SLEEPLOCK) { 490 if (*lock_list != NULL && (flags & LOP_TRYLOCK) == 0) { 491 mtx_unlock_spin(&w_mtx); 492 panic("blockable sleep lock (%s) %s @ %s:%d", 493 class->lc_name, lock->lo_name, file, line); 494 } 495 lock_list = &p->p_sleeplocks; 496 } 497 mtx_unlock_spin(&w_mtx); 498 499 /* 500 * Try locks do not block if they fail to acquire the lock, thus 501 * there is no danger of deadlocks or of switching while holding a 502 * spin lock if we acquire a lock via a try operation. 503 */ 504 if (flags & LOP_TRYLOCK) 505 goto out; 506 507 /* 508 * Is this the first lock acquired? If so, then no order checking 509 * is needed. 510 */ 511 if (*lock_list == NULL) 512 goto out; 513 514 /* 515 * Check to see if we are recursing on a lock we already own. 516 */ 517 lock1 = find_instance(*lock_list, lock); 518 if (lock1 != NULL) { 519 if ((lock1->li_flags & LI_EXCLUSIVE) != 0 && 520 (flags & LOP_EXCLUSIVE) == 0) { 521 printf("shared lock of (%s) %s @ %s:%d\n", 522 class->lc_name, lock->lo_name, file, line); 523 printf("while exclusively locked from %s:%d\n", 524 lock1->li_file, lock1->li_line); 525 panic("share->excl"); 526 } 527 if ((lock1->li_flags & LI_EXCLUSIVE) == 0 && 528 (flags & LOP_EXCLUSIVE) != 0) { 529 printf("exclusive lock of (%s) %s @ %s:%d\n", 530 class->lc_name, lock->lo_name, file, line); 531 printf("while share locked from %s:%d\n", 532 lock1->li_file, lock1->li_line); 533 panic("excl->share"); 534 } 535 lock1->li_flags++; 536 if ((lock->lo_flags & LO_RECURSABLE) == 0) { 537 printf( 538 "recursed on non-recursive lock (%s) %s @ %s:%d\n", 539 class->lc_name, lock->lo_name, file, line); 540 printf("first acquired @ %s:%d\n", lock1->li_file, 541 lock1->li_line); 542 panic("recurse"); 543 } 544 CTR3(KTR_WITNESS, "witness_lock: pid %d recursed on %s r=%d", 545 curproc->p_pid, lock->lo_name, 546 lock1->li_flags & LI_RECURSEMASK); 547 lock1->li_file = file; 548 lock1->li_line = line; 549 return; 550 } 551 552 /* 553 * Check for duplicate locks of the same type. Note that we only 554 * have to check for this on the last lock we just acquired. Any 555 * other cases will be caught as lock order violations. 556 */ 557 lock1 = &(*lock_list)->ll_children[(*lock_list)->ll_count - 1]; 558 w1 = lock1->li_lock->lo_witness; 559 if (w1 == w) { 560 if (w->w_same_squawked || dup_ok(w)) 561 goto out; 562 w->w_same_squawked = 1; 563 printf("acquiring duplicate lock of same type: \"%s\"\n", 564 lock->lo_name); 565 printf(" 1st @ %s:%d\n", lock1->li_file, lock1->li_line); 566 printf(" 2nd @ %s:%d\n", file, line); 567#ifdef DDB 568 go_into_ddb = 1; 569#endif /* DDB */ 570 goto out; 571 } 572 MPASS(!mtx_owned(&w_mtx)); 573 mtx_lock_spin(&w_mtx); 574 /* 575 * If we have a known higher number just say ok 576 */ 577 if (witness_watch > 1 && w->w_level > w1->w_level) { 578 mtx_unlock_spin(&w_mtx); 579 goto out; 580 } 581 if (isitmydescendant(w1, w)) { 582 mtx_unlock_spin(&w_mtx); 583 goto out; 584 } 585 for (j = 0, lle = *lock_list; lle != NULL; lle = lle->ll_next) { 586 for (i = lle->ll_count - 1; i >= 0; i--, j++) { 587 588 MPASS(j < WITNESS_COUNT); 589 lock1 = &lle->ll_children[i]; 590 w1 = lock1->li_lock->lo_witness; 591 592 /* 593 * If this lock doesn't undergo witness checking, 594 * then skip it. 595 */ 596 if (w1 == NULL) { 597 KASSERT((lock1->li_lock->lo_flags & LO_WITNESS) == 0, 598 ("lock missing witness structure")); 599 continue; 600 } 601 /* 602 * If we are locking Giant and we slept with this 603 * lock, then skip it. 604 */ 605 if ((lock1->li_flags & LI_SLEPT) != 0 && 606 lock == &Giant.mtx_object) 607 continue; 608 if (!isitmydescendant(w, w1)) 609 continue; 610 /* 611 * We have a lock order violation, check to see if it 612 * is allowed or has already been yelled about. 613 */ 614 mtx_unlock_spin(&w_mtx); 615 if (blessed(w, w1)) 616 goto out; 617 if (lock1->li_lock == &Giant.mtx_object) { 618 if (w1->w_Giant_squawked) 619 goto out; 620 else 621 w1->w_Giant_squawked = 1; 622 } else { 623 if (w1->w_other_squawked) 624 goto out; 625 else 626 w1->w_other_squawked = 1; 627 } 628 /* 629 * Ok, yell about it. 630 */ 631 printf("lock order reversal\n"); 632 /* 633 * Try to locate an earlier lock with 634 * witness w in our list. 635 */ 636 do { 637 lock2 = &lle->ll_children[i]; 638 MPASS(lock2->li_lock != NULL); 639 if (lock2->li_lock->lo_witness == w) 640 break; 641 i--; 642 if (i == 0 && lle->ll_next != NULL) { 643 lle = lle->ll_next; 644 i = lle->ll_count - 1; 645 MPASS(i != 0); 646 } 647 } while (i >= 0); 648 if (i < 0) { 649 printf(" 1st %p %s @ %s:%d\n", lock1->li_lock, 650 lock1->li_lock->lo_name, lock1->li_file, 651 lock1->li_line); 652 printf(" 2nd %p %s @ %s:%d\n", lock, 653 lock->lo_name, file, line); 654 } else { 655 printf(" 1st %p %s @ %s:%d\n", lock2->li_lock, 656 lock2->li_lock->lo_name, lock2->li_file, 657 lock2->li_line); 658 printf(" 2nd %p %s @ %s:%d\n", lock1->li_lock, 659 lock1->li_lock->lo_name, lock1->li_file, 660 lock1->li_line); 661 printf(" 3rd %p %s @ %s:%d\n", lock, 662 lock->lo_name, file, line); 663 } 664#ifdef DDB 665 go_into_ddb = 1; 666#endif /* DDB */ 667 goto out; 668 } 669 } 670 lock1 = &(*lock_list)->ll_children[(*lock_list)->ll_count - 1]; 671 CTR2(KTR_WITNESS, "Adding %s as a child of %s", lock->lo_name, 672 lock1->li_lock->lo_name); 673 if (!itismychild(lock1->li_lock->lo_witness, w)) 674 mtx_unlock_spin(&w_mtx); 675 676out: 677#ifdef DDB 678 if (witness_ddb && go_into_ddb) 679 Debugger(__func__); 680#endif /* DDB */ 681 w->w_file = file; 682 w->w_line = line; 683 684 lle = *lock_list; 685 if (lle == NULL || lle->ll_count == LOCK_NCHILDREN) { 686 lle = witness_lock_list_get(); 687 if (lle == NULL) 688 return; 689 lle->ll_next = *lock_list; 690 CTR2(KTR_WITNESS, "witness_lock: pid %d added lle %p", 691 curproc->p_pid, lle); 692 *lock_list = lle; 693 } 694 lock1 = &lle->ll_children[lle->ll_count++]; 695 lock1->li_lock = lock; 696 lock1->li_line = line; 697 lock1->li_file = file; 698 if ((flags & LOP_EXCLUSIVE) != 0) 699 lock1->li_flags = LI_EXCLUSIVE; 700 else 701 lock1->li_flags = 0; 702 CTR3(KTR_WITNESS, "witness_lock: pid %d added %s as lle[%d]", 703 curproc->p_pid, lock->lo_name, lle->ll_count - 1); 704} 705 706void 707witness_unlock(struct lock_object *lock, int flags, const char *file, int line) 708{ 709 struct lock_list_entry **lock_list, *lle; 710 struct lock_instance *instance; 711 struct lock_class *class; 712 struct proc *p; 713 critical_t s; 714 int i, j; 715 716 if (witness_cold || witness_dead || lock->lo_witness == NULL || 717 panicstr) 718 return; 719 p = curproc; 720 class = lock->lo_class; 721 if (class->lc_flags & LC_SLEEPLOCK) 722 lock_list = &p->p_sleeplocks; 723 else 724 lock_list = PCPU_PTR(spinlocks); 725 for (; *lock_list != NULL; lock_list = &(*lock_list)->ll_next) 726 for (i = 0; i < (*lock_list)->ll_count; i++) { 727 instance = &(*lock_list)->ll_children[i]; 728 if (instance->li_lock == lock) { 729 if ((instance->li_flags & LI_EXCLUSIVE) != 0 && 730 (flags & LOP_EXCLUSIVE) == 0) { 731 printf( 732 "shared unlock of (%s) %s @ %s:%d\n", 733 class->lc_name, lock->lo_name, 734 file, line); 735 printf( 736 "while exclusively locked from %s:%d\n", 737 instance->li_file, 738 instance->li_line); 739 panic("excl->ushare"); 740 } 741 if ((instance->li_flags & LI_EXCLUSIVE) == 0 && 742 (flags & LOP_EXCLUSIVE) != 0) { 743 printf( 744 "exclusive unlock of (%s) %s @ %s:%d\n", 745 class->lc_name, lock->lo_name, 746 file, line); 747 printf( 748 "while share locked from %s:%d\n", 749 instance->li_file, 750 instance->li_line); 751 panic("share->uexcl"); 752 } 753 /* If we are recursed, unrecurse. */ 754 if ((instance->li_flags & LI_RECURSEMASK) > 0) { 755 CTR3(KTR_WITNESS, 756 "witness_unlock: pid %d unrecursed on %s r=%d", 757 curproc->p_pid, 758 instance->li_lock->lo_name, 759 instance->li_flags); 760 instance->li_flags--; 761 goto out; 762 } 763 s = critical_enter(); 764 CTR3(KTR_WITNESS, 765 "witness_unlock: pid %d removed %s from lle[%d]", 766 curproc->p_pid, instance->li_lock->lo_name, 767 (*lock_list)->ll_count - 1); 768 (*lock_list)->ll_count--; 769 for (j = i; j < (*lock_list)->ll_count; j++) 770 (*lock_list)->ll_children[j] = 771 (*lock_list)->ll_children[j + 1]; 772 critical_exit(s); 773 if ((*lock_list)->ll_count == 0) { 774 lle = *lock_list; 775 *lock_list = lle->ll_next; 776 CTR2(KTR_WITNESS, 777 "witness_unlock: pid %d removed lle %p", 778 curproc->p_pid, lle); 779 witness_lock_list_free(lle); 780 } 781 goto out; 782 } 783 } 784 panic("lock (%s) %s not locked @ %s:%d", class->lc_name, lock->lo_name, 785 file, line); 786out: 787 /* 788 * We don't need to protect this PCPU_GET() here against preemption 789 * because if we hold any spinlocks then we are already protected, 790 * and if we don't we will get NULL if we hold no spinlocks even if 791 * we switch CPU's while reading it. 792 */ 793 if (class->lc_flags & LC_SLEEPLOCK) { 794 if ((flags & LOP_NOSWITCH) == 0 && PCPU_GET(spinlocks) != NULL) 795 panic("switchable sleep unlock (%s) %s @ %s:%d", 796 class->lc_name, lock->lo_name, file, line); 797 } 798} 799 800/* 801 * Warn if any held locks are not sleepable. Note that Giant and the lock 802 * passed in are both special cases since they are both released during the 803 * sleep process and aren't actually held while the process is asleep. 804 */ 805int 806witness_sleep(int check_only, struct lock_object *lock, const char *file, 807 int line) 808{ 809 struct lock_list_entry **lock_list, *lle; 810 struct lock_instance *lock1; 811 struct proc *p; 812 critical_t savecrit; 813 int i, n; 814 815 if (witness_dead || panicstr) 816 return (0); 817 KASSERT(!witness_cold, ("%s: witness_cold\n", __func__)); 818 n = 0; 819 /* 820 * Preemption bad because we need PCPU_PTR(spinlocks) to not change. 821 */ 822 savecrit = critical_enter(); 823 p = curproc; 824 lock_list = &p->p_sleeplocks; 825again: 826 for (lle = *lock_list; lle != NULL; lle = lle->ll_next) 827 for (i = lle->ll_count - 1; i >= 0; i--) { 828 lock1 = &lle->ll_children[i]; 829 if (lock1->li_lock == lock || 830 lock1->li_lock == &Giant.mtx_object) 831 continue; 832 if ((lock1->li_lock->lo_flags & LO_SLEEPABLE) != 0) { 833 if (check_only == 0) { 834 CTR3(KTR_WITNESS, 835 "pid %d: sleeping with (%s) %s held", 836 curproc->p_pid, 837 lock1->li_lock->lo_class->lc_name, 838 lock1->li_lock->lo_name); 839 lock1->li_flags |= LI_SLEPT; 840 } 841 continue; 842 } 843 n++; 844 printf("%s:%d: %s with \"%s\" locked from %s:%d\n", 845 file, line, check_only ? "could sleep" : "sleeping", 846 lock1->li_lock->lo_name, lock1->li_file, 847 lock1->li_line); 848 } 849 if (lock_list == &p->p_sleeplocks) { 850 lock_list = PCPU_PTR(spinlocks); 851 goto again; 852 } 853#ifdef DDB 854 if (witness_ddb && n) 855 Debugger(__func__); 856#endif /* DDB */ 857 critical_exit(savecrit); 858 return (n); 859} 860 861static struct witness * 862enroll(const char *description, struct lock_class *lock_class) 863{ 864 struct witness *w; 865 866 if (!witness_watch || witness_dead) 867 return (NULL); 868 869 if ((lock_class->lc_flags & LC_SPINLOCK) && witness_skipspin) 870 return (NULL); 871 mtx_lock_spin(&w_mtx); 872 STAILQ_FOREACH(w, &w_all, w_list) { 873 if (strcmp(description, w->w_name) == 0) { 874 w->w_refcount++; 875 mtx_unlock_spin(&w_mtx); 876 if (lock_class != w->w_class) 877 panic( 878 "lock (%s) %s does not match earlier (%s) lock", 879 description, lock_class->lc_name, 880 w->w_class->lc_name); 881 return (w); 882 } 883 } 884 /* 885 * This isn't quite right, as witness_cold is still 0 while we 886 * enroll all the locks initialized before witness_initialize(). 887 */ 888 if ((lock_class->lc_flags & LC_SPINLOCK) && !witness_cold) { 889 mtx_unlock_spin(&w_mtx); 890 panic("spin lock %s not in order list", description); 891 } 892 if ((w = witness_get()) == NULL) 893 return (NULL); 894 w->w_name = description; 895 w->w_class = lock_class; 896 w->w_refcount = 1; 897 STAILQ_INSERT_HEAD(&w_all, w, w_list); 898 if (lock_class->lc_flags & LC_SPINLOCK) 899 STAILQ_INSERT_HEAD(&w_spin, w, w_typelist); 900 else if (lock_class->lc_flags & LC_SLEEPLOCK) 901 STAILQ_INSERT_HEAD(&w_sleep, w, w_typelist); 902 else { 903 mtx_unlock_spin(&w_mtx); 904 panic("lock class %s is not sleep or spin", 905 lock_class->lc_name); 906 } 907 mtx_unlock_spin(&w_mtx); 908 909 return (w); 910} 911 912static int 913itismychild(struct witness *parent, struct witness *child) 914{ 915 static int recursed; 916 struct witness_child_list_entry **wcl; 917 struct witness_list *list; 918 919 MPASS(child != NULL && parent != NULL); 920 if ((parent->w_class->lc_flags & (LC_SLEEPLOCK | LC_SPINLOCK)) != 921 (child->w_class->lc_flags & (LC_SLEEPLOCK | LC_SPINLOCK))) 922 panic( 923 "%s: parent (%s) and child (%s) are not the same lock type", 924 __func__, parent->w_class->lc_name, 925 child->w_class->lc_name); 926 927 /* 928 * Insert "child" after "parent" 929 */ 930 wcl = &parent->w_children; 931 while (*wcl != NULL && (*wcl)->wcl_count == WITNESS_NCHILDREN) 932 wcl = &(*wcl)->wcl_next; 933 934 if (*wcl == NULL) { 935 *wcl = witness_child_get(); 936 if (*wcl == NULL) 937 return (1); 938 } 939 940 (*wcl)->wcl_children[(*wcl)->wcl_count++] = child; 941 942 /* 943 * Now prune whole tree. We look for cases where a lock is now 944 * both a descendant and a direct child of a given lock. In that 945 * case, we want to remove the direct child link from the tree. 946 */ 947 if (recursed) 948 return (0); 949 recursed = 1; 950 if (parent->w_class->lc_flags & LC_SLEEPLOCK) 951 list = &w_sleep; 952 else 953 list = &w_spin; 954 STAILQ_FOREACH(child, list, w_typelist) { 955 STAILQ_FOREACH(parent, list, w_typelist) { 956 if (!isitmychild(parent, child)) 957 continue; 958 removechild(parent, child); 959 if (isitmydescendant(parent, child)) 960 continue; 961 itismychild(parent, child); 962 } 963 } 964 recursed = 0; 965 witness_levelall(); 966 return (0); 967} 968 969static void 970removechild(struct witness *parent, struct witness *child) 971{ 972 struct witness_child_list_entry **wcl, *wcl1; 973 int i; 974 975 for (wcl = &parent->w_children; *wcl != NULL; wcl = &(*wcl)->wcl_next) 976 for (i = 0; i < (*wcl)->wcl_count; i++) 977 if ((*wcl)->wcl_children[i] == child) 978 goto found; 979 return; 980found: 981 (*wcl)->wcl_count--; 982 if ((*wcl)->wcl_count > i) 983 (*wcl)->wcl_children[i] = 984 (*wcl)->wcl_children[(*wcl)->wcl_count]; 985 MPASS((*wcl)->wcl_children[i] != NULL); 986 987 if ((*wcl)->wcl_count != 0) 988 return; 989 990 wcl1 = *wcl; 991 *wcl = wcl1->wcl_next; 992 witness_child_free(wcl1); 993} 994 995static int 996isitmychild(struct witness *parent, struct witness *child) 997{ 998 struct witness_child_list_entry *wcl; 999 int i; 1000 1001 for (wcl = parent->w_children; wcl != NULL; wcl = wcl->wcl_next) { 1002 for (i = 0; i < wcl->wcl_count; i++) { 1003 if (wcl->wcl_children[i] == child) 1004 return (1); 1005 } 1006 } 1007 return (0); 1008} 1009 1010static int 1011isitmydescendant(struct witness *parent, struct witness *child) 1012{ 1013 struct witness_child_list_entry *wcl; 1014 int i, j; 1015 1016 if (isitmychild(parent, child)) 1017 return (1); 1018 j = 0; 1019 for (wcl = parent->w_children; wcl != NULL; wcl = wcl->wcl_next) { 1020 MPASS(j < 1000); 1021 for (i = 0; i < wcl->wcl_count; i++) { 1022 if (isitmydescendant(wcl->wcl_children[i], child)) 1023 return (1); 1024 } 1025 j++; 1026 } 1027 return (0); 1028} 1029 1030void 1031witness_levelall (void) 1032{ 1033 struct witness_list *list; 1034 struct witness *w, *w1; 1035 1036 /* 1037 * First clear all levels. 1038 */ 1039 STAILQ_FOREACH(w, &w_all, w_list) { 1040 w->w_level = 0; 1041 } 1042 1043 /* 1044 * Look for locks with no parent and level all their descendants. 1045 */ 1046 STAILQ_FOREACH(w, &w_all, w_list) { 1047 /* 1048 * This is just an optimization, technically we could get 1049 * away just walking the all list each time. 1050 */ 1051 if (w->w_class->lc_flags & LC_SLEEPLOCK) 1052 list = &w_sleep; 1053 else 1054 list = &w_spin; 1055 STAILQ_FOREACH(w1, list, w_typelist) { 1056 if (isitmychild(w1, w)) 1057 goto skip; 1058 } 1059 witness_leveldescendents(w, 0); 1060 skip: 1061 } 1062} 1063 1064static void 1065witness_leveldescendents(struct witness *parent, int level) 1066{ 1067 struct witness_child_list_entry *wcl; 1068 int i; 1069 1070 if (parent->w_level < level) 1071 parent->w_level = level; 1072 level++; 1073 for (wcl = parent->w_children; wcl != NULL; wcl = wcl->wcl_next) 1074 for (i = 0; i < wcl->wcl_count; i++) 1075 witness_leveldescendents(wcl->wcl_children[i], level); 1076} 1077 1078static void 1079witness_displaydescendants(void(*prnt)(const char *fmt, ...), 1080 struct witness *parent) 1081{ 1082 struct witness_child_list_entry *wcl; 1083 int i, level; 1084 1085 level = parent->w_level; 1086 1087 prnt("%-2d", level); 1088 for (i = 0; i < level; i++) 1089 prnt(" "); 1090 prnt("%s", parent->w_name); 1091 if (parent->w_file != NULL) 1092 prnt(" -- last acquired @ %s:%d\n", parent->w_file, 1093 parent->w_line); 1094 1095 for (wcl = parent->w_children; wcl != NULL; wcl = wcl->wcl_next) 1096 for (i = 0; i < wcl->wcl_count; i++) 1097 witness_displaydescendants(prnt, 1098 wcl->wcl_children[i]); 1099} 1100 1101static int 1102dup_ok(struct witness *w) 1103{ 1104 const char **dup; 1105 1106 for (dup = dup_list; *dup != NULL; dup++) 1107 if (strcmp(w->w_name, *dup) == 0) 1108 return (1); 1109 return (0); 1110} 1111 1112static int 1113blessed(struct witness *w1, struct witness *w2) 1114{ 1115 int i; 1116 struct witness_blessed *b; 1117 1118 for (i = 0; i < blessed_count; i++) { 1119 b = &blessed_list[i]; 1120 if (strcmp(w1->w_name, b->b_lock1) == 0) { 1121 if (strcmp(w2->w_name, b->b_lock2) == 0) 1122 return (1); 1123 continue; 1124 } 1125 if (strcmp(w1->w_name, b->b_lock2) == 0) 1126 if (strcmp(w2->w_name, b->b_lock1) == 0) 1127 return (1); 1128 } 1129 return (0); 1130} 1131 1132static struct witness * 1133witness_get(void) 1134{ 1135 struct witness *w; 1136 1137 if (witness_dead) { 1138 mtx_unlock_spin(&w_mtx); 1139 return (NULL); 1140 } 1141 if (STAILQ_EMPTY(&w_free)) { 1142 witness_dead = 1; 1143 mtx_unlock_spin(&w_mtx); 1144 printf("%s: witness exhausted\n", __func__); 1145 return (NULL); 1146 } 1147 w = STAILQ_FIRST(&w_free); 1148 STAILQ_REMOVE_HEAD(&w_free, w_list); 1149 bzero(w, sizeof(*w)); 1150 return (w); 1151} 1152 1153static void 1154witness_free(struct witness *w) 1155{ 1156 1157 STAILQ_INSERT_HEAD(&w_free, w, w_list); 1158} 1159 1160static struct witness_child_list_entry * 1161witness_child_get(void) 1162{ 1163 struct witness_child_list_entry *wcl; 1164 1165 if (witness_dead) { 1166 mtx_unlock_spin(&w_mtx); 1167 return (NULL); 1168 } 1169 wcl = w_child_free; 1170 if (wcl == NULL) { 1171 witness_dead = 1; 1172 mtx_unlock_spin(&w_mtx); 1173 printf("%s: witness exhausted\n", __func__); 1174 return (NULL); 1175 } 1176 w_child_free = wcl->wcl_next; 1177 bzero(wcl, sizeof(*wcl)); 1178 return (wcl); 1179} 1180 1181static void 1182witness_child_free(struct witness_child_list_entry *wcl) 1183{ 1184 1185 wcl->wcl_next = w_child_free; 1186 w_child_free = wcl; 1187} 1188 1189static struct lock_list_entry * 1190witness_lock_list_get(void) 1191{ 1192 struct lock_list_entry *lle; 1193 1194 if (witness_dead) 1195 return (NULL); 1196 mtx_lock_spin(&w_mtx); 1197 lle = w_lock_list_free; 1198 if (lle == NULL) { 1199 witness_dead = 1; 1200 mtx_unlock_spin(&w_mtx); 1201 printf("%s: witness exhausted\n", __func__); 1202 return (NULL); 1203 } 1204 w_lock_list_free = lle->ll_next; 1205 mtx_unlock_spin(&w_mtx); 1206 bzero(lle, sizeof(*lle)); 1207 return (lle); 1208} 1209 1210static void 1211witness_lock_list_free(struct lock_list_entry *lle) 1212{ 1213 1214 mtx_lock_spin(&w_mtx); 1215 lle->ll_next = w_lock_list_free; 1216 w_lock_list_free = lle; 1217 mtx_unlock_spin(&w_mtx); 1218} 1219 1220static struct lock_instance * 1221find_instance(struct lock_list_entry *lock_list, struct lock_object *lock) 1222{ 1223 struct lock_list_entry *lle; 1224 struct lock_instance *instance; 1225 int i; 1226 1227 for (lle = lock_list; lle != NULL; lle = lle->ll_next) 1228 for (i = lle->ll_count - 1; i >= 0; i--) { 1229 instance = &lle->ll_children[i]; 1230 if (instance->li_lock == lock) 1231 return (instance); 1232 } 1233 return (NULL); 1234} 1235 1236int 1237witness_list_locks(struct lock_list_entry **lock_list) 1238{ 1239 struct lock_list_entry *lle; 1240 struct lock_instance *instance; 1241 struct lock_object *lock; 1242 int i, nheld; 1243 1244 nheld = 0; 1245 for (lle = *lock_list; lle != NULL; lle = lle->ll_next) 1246 for (i = lle->ll_count - 1; i >= 0; i--) { 1247 instance = &lle->ll_children[i]; 1248 lock = instance->li_lock; 1249 printf("%s (%s) %s (%p) locked @ %s:%d\n", 1250 (instance->li_flags & LI_EXCLUSIVE) != 0 ? 1251 "exclusive" : "shared", 1252 lock->lo_class->lc_name, lock->lo_name, lock, 1253 instance->li_file, instance->li_line); 1254 nheld++; 1255 } 1256 return (nheld); 1257} 1258 1259/* 1260 * Calling this on p != curproc is bad unless we are in ddb. 1261 */ 1262int 1263witness_list(struct proc *p) 1264{ 1265 critical_t savecrit; 1266 int nheld; 1267 1268 KASSERT(p == curproc || db_active, 1269 ("%s: p != curproc and we aren't in the debugger", __func__)); 1270 KASSERT(!witness_cold, ("%s: witness_cold", __func__)); 1271 1272 if (!db_active && witness_dead) 1273 return (0); 1274 1275 nheld = witness_list_locks(&p->p_sleeplocks); 1276 1277 /* 1278 * We only handle spinlocks if p == curproc. This is somewhat broken 1279 * if p is currently executing on some other CPU and holds spin locks 1280 * as we won't display those locks. If we had a MI way of getting 1281 * the per-cpu data for a given cpu then we could use p->p_oncpu to 1282 * get the list of spinlocks for this process and "fix" this. 1283 */ 1284 if (p == curproc) { 1285 /* 1286 * Preemption bad because we need PCPU_PTR(spinlocks) to not 1287 * change. 1288 */ 1289 savecrit = critical_enter(); 1290 nheld += witness_list_locks(PCPU_PTR(spinlocks)); 1291 critical_exit(savecrit); 1292 } 1293 1294 return (nheld); 1295} 1296 1297void 1298witness_save(struct lock_object *lock, const char **filep, int *linep) 1299{ 1300 struct lock_instance *instance; 1301 1302 KASSERT(!witness_cold, ("%s: witness_cold\n", __func__)); 1303 if (lock->lo_witness == NULL || witness_dead) 1304 return; 1305 1306 KASSERT(lock->lo_class->lc_flags & LC_SLEEPLOCK, 1307 ("%s: lock (%s) %s is not a sleep lock", __func__, 1308 lock->lo_class->lc_name, lock->lo_name)); 1309 instance = find_instance(curproc->p_sleeplocks, lock); 1310 KASSERT(instance != NULL, ("%s: lock (%s) %s not locked", __func__, 1311 lock->lo_class->lc_name, lock->lo_name)); 1312 1313 *filep = instance->li_file; 1314 *linep = instance->li_line; 1315} 1316 1317void 1318witness_restore(struct lock_object *lock, const char *file, int line) 1319{ 1320 struct lock_instance *instance; 1321 1322 KASSERT(!witness_cold, ("%s: witness_cold\n", __func__)); 1323 if (lock->lo_witness == NULL || witness_dead) 1324 return; 1325 1326 KASSERT(lock->lo_class->lc_flags & LC_SLEEPLOCK, 1327 ("%s: lock (%s) %s is not a sleep lock", __func__, 1328 lock->lo_class->lc_name, lock->lo_name)); 1329 instance = find_instance(curproc->p_sleeplocks, lock); 1330 KASSERT(instance != NULL, ("%s: lock (%s) %s not locked", __func__, 1331 lock->lo_class->lc_name, lock->lo_name)); 1332 1333 lock->lo_witness->w_file = file; 1334 lock->lo_witness->w_line = line; 1335 instance->li_file = file; 1336 instance->li_line = line; 1337} 1338 1339#ifdef DDB 1340 1341DB_SHOW_COMMAND(locks, db_witness_list) 1342{ 1343 struct proc *p; 1344 pid_t pid; 1345 1346 if (have_addr) { 1347 pid = (addr % 16) + ((addr >> 4) % 16) * 10 + 1348 ((addr >> 8) % 16) * 100 + ((addr >> 12) % 16) * 1000 + 1349 ((addr >> 16) % 16) * 10000; 1350 1351 /* sx_slock(&allproc_lock); */ 1352 LIST_FOREACH(p, &allproc, p_list) { 1353 if (p->p_pid == pid) 1354 break; 1355 } 1356 /* sx_sunlock(&allproc_lock); */ 1357 if (p == NULL) { 1358 db_printf("pid %d not found\n", pid); 1359 return; 1360 } 1361 } else 1362 p = curproc; 1363 1364 witness_list(p); 1365} 1366 1367DB_SHOW_COMMAND(witness, db_witness_display) 1368{ 1369 1370 witness_display(db_printf); 1371} 1372#endif 1373