1 /* 2 * Copyright (c) 1995 3 * The Regents of the University of California. All rights reserved. 4 * 5 * Copyright (C) 1997 6 * John S. Dyson. All rights reserved. 7 * 8 * This code contains ideas from software contributed to Berkeley by 9 * Avadis Tevanian, Jr., Michael Wayne Young, and the Mach Operating 10 * System project at Carnegie-Mellon University. 11 * 12 * Redistribution and use in source and binary forms, with or without 13 * modification, are permitted provided that the following conditions 14 * are met: 15 * 1. Redistributions of source code must retain the above copyright 16 * notice, this list of conditions and the following disclaimer. 17 * 2. Redistributions in binary form must reproduce the above copyright 18 * notice, this list of conditions and the following disclaimer in the 19 * documentation and/or other materials provided with the distribution. 20 * 3. All advertising materials mentioning features or use of this software 21 * must display the following acknowledgement: 22 * This product includes software developed by the University of 23 * California, Berkeley and its contributors. 24 * 4. Neither the name of the University nor the names of its contributors 25 * may be used to endorse or promote products derived from this software 26 * without specific prior written permission. 27 * 28 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 29 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 30 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 31 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 32 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 33 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 34 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 35 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 36 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 37 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 38 * SUCH DAMAGE. 39 * 40 * @(#)kern_lock.c 8.18 (Berkeley) 5/21/95 41 * $FreeBSD: src/sys/kern/kern_lock.c,v 1.31.2.3 2001/12/25 01:44:44 dillon Exp $ 42 * $DragonFly: src/sys/kern/kern_lock.c,v 1.27 2008/01/09 10:59:12 corecode Exp $ 43 */ 44 45 #include "opt_lint.h" 46 47 #include <sys/param.h> 48 #include <sys/systm.h> 49 #include <sys/kernel.h> 50 #include <sys/proc.h> 51 #include <sys/lock.h> 52 #include <sys/sysctl.h> 53 #include <sys/spinlock.h> 54 #include <sys/thread2.h> 55 #include <sys/spinlock2.h> 56 57 /* 58 * Locking primitives implementation. 59 * Locks provide shared/exclusive sychronization. 60 */ 61 62 #ifdef DEBUG_LOCKS 63 #define COUNT(td, x) (td)->td_locks += (x) 64 #else 65 #define COUNT(td, x) 66 #endif 67 68 #define LOCK_WAIT_TIME 100 69 #define LOCK_SAMPLE_WAIT 7 70 71 #if defined(DIAGNOSTIC) 72 #define LOCK_INLINE 73 #else 74 #define LOCK_INLINE __inline 75 #endif 76 77 #define LK_ALL (LK_HAVE_EXCL | LK_WANT_EXCL | LK_WANT_UPGRADE | \ 78 LK_SHARE_NONZERO | LK_WAIT_NONZERO) 79 80 static int acquire(struct lock *lkp, int extflags, int wanted); 81 82 static LOCK_INLINE void 83 sharelock(struct lock *lkp, int incr) { 84 lkp->lk_flags |= LK_SHARE_NONZERO; 85 lkp->lk_sharecount += incr; 86 } 87 88 static LOCK_INLINE int 89 shareunlock(struct lock *lkp, int decr) 90 { 91 int dowakeup = 0; 92 93 KASSERT(lkp->lk_sharecount >= decr, ("shareunlock: count < decr")); 94 95 if (lkp->lk_sharecount == decr) { 96 lkp->lk_flags &= ~LK_SHARE_NONZERO; 97 if (lkp->lk_flags & (LK_WANT_UPGRADE | LK_WANT_EXCL)) { 98 dowakeup = 1; 99 } 100 lkp->lk_sharecount = 0; 101 } else { 102 lkp->lk_sharecount -= decr; 103 } 104 return(dowakeup); 105 } 106 107 /* 108 * lock acquisition helper routine. Called with the lock's spinlock held. 109 */ 110 static int 111 acquire(struct lock *lkp, int extflags, int wanted) 112 { 113 int error; 114 115 if ((extflags & LK_NOWAIT) && (lkp->lk_flags & wanted)) { 116 return EBUSY; 117 } 118 119 while ((lkp->lk_flags & wanted) != 0) { 120 lkp->lk_flags |= LK_WAIT_NONZERO; 121 lkp->lk_waitcount++; 122 123 /* 124 * Atomic spinlock release/sleep/reacquire. 125 */ 126 error = ssleep(lkp, &lkp->lk_spinlock, 127 ((extflags & LK_PCATCH) ? PCATCH : 0), 128 lkp->lk_wmesg, 129 ((extflags & LK_TIMELOCK) ? lkp->lk_timo : 0)); 130 if (lkp->lk_waitcount == 1) { 131 lkp->lk_flags &= ~LK_WAIT_NONZERO; 132 lkp->lk_waitcount = 0; 133 } else { 134 lkp->lk_waitcount--; 135 } 136 if (error) 137 return error; 138 if (extflags & LK_SLEEPFAIL) 139 return ENOLCK; 140 } 141 return 0; 142 } 143 144 /* 145 * Set, change, or release a lock. 146 * 147 * Shared requests increment the shared count. Exclusive requests set the 148 * LK_WANT_EXCL flag (preventing further shared locks), and wait for already 149 * accepted shared locks and shared-to-exclusive upgrades to go away. 150 * 151 * A spinlock is held for most of the procedure. We must not do anything 152 * fancy while holding the spinlock. 153 */ 154 int 155 #ifndef DEBUG_LOCKS 156 lockmgr(struct lock *lkp, u_int flags) 157 #else 158 debuglockmgr(struct lock *lkp, u_int flags, 159 const char *name, const char *file, int line) 160 #endif 161 { 162 thread_t td; 163 int error; 164 int extflags; 165 int dowakeup; 166 #ifdef DEBUG_LOCKS 167 int i; 168 #endif 169 170 error = 0; 171 dowakeup = 0; 172 173 if (mycpu->gd_intr_nesting_level && 174 (flags & LK_NOWAIT) == 0 && 175 (flags & LK_TYPE_MASK) != LK_RELEASE && 176 panic_cpu_gd != mycpu 177 ) { 178 179 #ifndef DEBUG_LOCKS 180 panic("lockmgr %s from %p: called from interrupt, ipi, " 181 "or hard code section", 182 lkp->lk_wmesg, ((int **)&lkp)[-1]); 183 #else 184 panic("lockmgr %s from %s:%d: called from interrupt, ipi, " 185 "or hard code section", 186 lkp->lk_wmesg, file, line); 187 #endif 188 } 189 190 #ifdef DEBUG_LOCKS 191 if (mycpu->gd_spinlocks_wr && 192 ((flags & LK_NOWAIT) == 0) 193 ) { 194 panic("lockmgr %s from %s:%d: called with %d spinlocks held", 195 lkp->lk_wmesg, file, line, mycpu->gd_spinlocks_wr); 196 } 197 #endif 198 199 spin_lock(&lkp->lk_spinlock); 200 201 extflags = (flags | lkp->lk_flags) & LK_EXTFLG_MASK; 202 td = curthread; 203 204 switch (flags & LK_TYPE_MASK) { 205 case LK_SHARED: 206 /* 207 * If we are not the exclusive lock holder, we have to block 208 * while there is an exclusive lock holder or while an 209 * exclusive lock request or upgrade request is in progress. 210 * 211 * However, if TDF_DEADLKTREAT is set, we override exclusive 212 * lock requests or upgrade requests ( but not the exclusive 213 * lock itself ). 214 */ 215 if (lkp->lk_lockholder != td) { 216 if (td->td_flags & TDF_DEADLKTREAT) { 217 error = acquire( 218 lkp, 219 extflags, 220 LK_HAVE_EXCL 221 ); 222 } else { 223 error = acquire( 224 lkp, 225 extflags, 226 LK_HAVE_EXCL | LK_WANT_EXCL | 227 LK_WANT_UPGRADE 228 ); 229 } 230 if (error) 231 break; 232 sharelock(lkp, 1); 233 COUNT(td, 1); 234 break; 235 } 236 /* 237 * We hold an exclusive lock, so downgrade it to shared. 238 * An alternative would be to fail with EDEADLK. 239 */ 240 sharelock(lkp, 1); 241 COUNT(td, 1); 242 /* fall into downgrade */ 243 244 case LK_DOWNGRADE: 245 if (lkp->lk_lockholder != td || lkp->lk_exclusivecount == 0) { 246 spin_unlock(&lkp->lk_spinlock); 247 panic("lockmgr: not holding exclusive lock"); 248 } 249 250 #ifdef DEBUG_LOCKS 251 for (i = 0; i < LOCKMGR_DEBUG_ARRAY_SIZE; i++) { 252 if (td->td_lockmgr_stack[i] == lkp && 253 td->td_lockmgr_stack_id[i] > 0 254 ) { 255 td->td_lockmgr_stack_id[i]--; 256 break; 257 } 258 } 259 #endif 260 261 sharelock(lkp, lkp->lk_exclusivecount); 262 lkp->lk_exclusivecount = 0; 263 lkp->lk_flags &= ~LK_HAVE_EXCL; 264 lkp->lk_lockholder = LK_NOTHREAD; 265 if (lkp->lk_waitcount) 266 dowakeup = 1; 267 break; 268 269 case LK_EXCLUPGRADE: 270 /* 271 * If another process is ahead of us to get an upgrade, 272 * then we want to fail rather than have an intervening 273 * exclusive access. 274 */ 275 if (lkp->lk_flags & LK_WANT_UPGRADE) { 276 dowakeup = shareunlock(lkp, 1); 277 COUNT(td, -1); 278 error = EBUSY; 279 break; 280 } 281 /* fall into normal upgrade */ 282 283 case LK_UPGRADE: 284 /* 285 * Upgrade a shared lock to an exclusive one. If another 286 * shared lock has already requested an upgrade to an 287 * exclusive lock, our shared lock is released and an 288 * exclusive lock is requested (which will be granted 289 * after the upgrade). If we return an error, the file 290 * will always be unlocked. 291 */ 292 if ((lkp->lk_lockholder == td) || (lkp->lk_sharecount <= 0)) { 293 spin_unlock(&lkp->lk_spinlock); 294 panic("lockmgr: upgrade exclusive lock"); 295 } 296 dowakeup += shareunlock(lkp, 1); 297 COUNT(td, -1); 298 /* 299 * If we are just polling, check to see if we will block. 300 */ 301 if ((extflags & LK_NOWAIT) && 302 ((lkp->lk_flags & LK_WANT_UPGRADE) || 303 lkp->lk_sharecount > 1)) { 304 error = EBUSY; 305 break; 306 } 307 if ((lkp->lk_flags & LK_WANT_UPGRADE) == 0) { 308 /* 309 * We are first shared lock to request an upgrade, so 310 * request upgrade and wait for the shared count to 311 * drop to zero, then take exclusive lock. 312 * 313 * Although I don't think this can occur for 314 * robustness we also wait for any exclusive locks 315 * to be released. LK_WANT_UPGRADE is supposed to 316 * prevent new exclusive locks but might not in the 317 * future. 318 */ 319 lkp->lk_flags |= LK_WANT_UPGRADE; 320 error = acquire(lkp, extflags, 321 LK_HAVE_EXCL | LK_SHARE_NONZERO); 322 lkp->lk_flags &= ~LK_WANT_UPGRADE; 323 324 if (error) 325 break; 326 lkp->lk_flags |= LK_HAVE_EXCL; 327 lkp->lk_lockholder = td; 328 if (lkp->lk_exclusivecount != 0) { 329 spin_unlock(&lkp->lk_spinlock); 330 panic("lockmgr(1): non-zero exclusive count"); 331 } 332 lkp->lk_exclusivecount = 1; 333 #if defined(DEBUG_LOCKS) 334 lkp->lk_filename = file; 335 lkp->lk_lineno = line; 336 lkp->lk_lockername = name; 337 338 for (i = 0; i < LOCKMGR_DEBUG_ARRAY_SIZE; i++) { 339 /* 340 * Recursive lockmgr path 341 */ 342 if (td->td_lockmgr_stack[i] == lkp && 343 td->td_lockmgr_stack_id[i] != 0 344 ) { 345 td->td_lockmgr_stack_id[i]++; 346 goto lkmatch2; 347 } 348 } 349 350 for (i = 0; i < LOCKMGR_DEBUG_ARRAY_SIZE; i++) { 351 /* 352 * Use new lockmgr tracking slot 353 */ 354 if (td->td_lockmgr_stack_id[i] == 0) { 355 td->td_lockmgr_stack_id[i]++; 356 td->td_lockmgr_stack[i] = lkp; 357 break; 358 } 359 } 360 lkmatch2: 361 ; 362 #endif 363 COUNT(td, 1); 364 break; 365 } 366 /* 367 * Someone else has requested upgrade. Release our shared 368 * lock, awaken upgrade requestor if we are the last shared 369 * lock, then request an exclusive lock. 370 */ 371 if ( (lkp->lk_flags & (LK_SHARE_NONZERO|LK_WAIT_NONZERO)) == 372 LK_WAIT_NONZERO) { 373 ++dowakeup; 374 } 375 /* fall into exclusive request */ 376 377 case LK_EXCLUSIVE: 378 if (lkp->lk_lockholder == td && td != LK_KERNTHREAD) { 379 /* 380 * Recursive lock. 381 */ 382 if ((extflags & (LK_NOWAIT | LK_CANRECURSE)) == 0) { 383 spin_unlock(&lkp->lk_spinlock); 384 panic("lockmgr: locking against myself"); 385 } 386 if ((extflags & LK_CANRECURSE) != 0) { 387 lkp->lk_exclusivecount++; 388 COUNT(td, 1); 389 break; 390 } 391 } 392 /* 393 * If we are just polling, check to see if we will sleep. 394 */ 395 if ((extflags & LK_NOWAIT) && 396 (lkp->lk_flags & (LK_HAVE_EXCL | LK_WANT_EXCL | 397 LK_WANT_UPGRADE | LK_SHARE_NONZERO))) { 398 error = EBUSY; 399 break; 400 } 401 /* 402 * Wait for exclusive lock holders to release and try to 403 * acquire the want_exclusive flag. 404 */ 405 error = acquire(lkp, extflags, (LK_HAVE_EXCL | LK_WANT_EXCL)); 406 if (error) 407 break; 408 lkp->lk_flags |= LK_WANT_EXCL; 409 410 /* 411 * Wait for shared locks and upgrades to finish. We can lose 412 * the race against a successful shared lock upgrade in which 413 * case LK_HAVE_EXCL will get set regardless of our 414 * acquisition of LK_WANT_EXCL, so we have to acquire 415 * LK_HAVE_EXCL here as well. 416 */ 417 error = acquire(lkp, extflags, LK_HAVE_EXCL | 418 LK_WANT_UPGRADE | 419 LK_SHARE_NONZERO); 420 lkp->lk_flags &= ~LK_WANT_EXCL; 421 if (error) 422 break; 423 lkp->lk_flags |= LK_HAVE_EXCL; 424 lkp->lk_lockholder = td; 425 if (lkp->lk_exclusivecount != 0) { 426 spin_unlock(&lkp->lk_spinlock); 427 panic("lockmgr(2): non-zero exclusive count"); 428 } 429 lkp->lk_exclusivecount = 1; 430 #if defined(DEBUG_LOCKS) 431 lkp->lk_filename = file; 432 lkp->lk_lineno = line; 433 lkp->lk_lockername = name; 434 435 for (i = 0; i < LOCKMGR_DEBUG_ARRAY_SIZE; i++) { 436 /* 437 * Recursive lockmgr path 438 */ 439 if (td->td_lockmgr_stack[i] == lkp && 440 td->td_lockmgr_stack_id[i] != 0 441 ) { 442 td->td_lockmgr_stack_id[i]++; 443 goto lkmatch1; 444 } 445 } 446 447 for (i = 0; i < LOCKMGR_DEBUG_ARRAY_SIZE; i++) { 448 /* 449 * Use new lockmgr tracking slot 450 */ 451 if (td->td_lockmgr_stack_id[i] == 0) { 452 td->td_lockmgr_stack_id[i]++; 453 td->td_lockmgr_stack[i] = lkp; 454 break; 455 } 456 } 457 lkmatch1: 458 ; 459 #endif 460 COUNT(td, 1); 461 break; 462 463 case LK_RELEASE: 464 if (lkp->lk_exclusivecount != 0) { 465 if (lkp->lk_lockholder != td && 466 lkp->lk_lockholder != LK_KERNTHREAD) { 467 spin_unlock(&lkp->lk_spinlock); 468 panic("lockmgr: pid %d, not %s thr %p/%p unlocking", 469 (td->td_proc ? td->td_proc->p_pid : -1), 470 "exclusive lock holder", 471 td, lkp->lk_lockholder); 472 } 473 if (lkp->lk_lockholder != LK_KERNTHREAD) { 474 COUNT(td, -1); 475 } 476 if (lkp->lk_exclusivecount == 1) { 477 lkp->lk_flags &= ~LK_HAVE_EXCL; 478 lkp->lk_lockholder = LK_NOTHREAD; 479 lkp->lk_exclusivecount = 0; 480 } else { 481 lkp->lk_exclusivecount--; 482 } 483 #ifdef DEBUG_LOCKS 484 for (i = 0; i < LOCKMGR_DEBUG_ARRAY_SIZE; i++) { 485 if (td->td_lockmgr_stack[i] == lkp && 486 td->td_lockmgr_stack_id[i] > 0 487 ) { 488 td->td_lockmgr_stack_id[i]--; 489 break; 490 } 491 } 492 #endif 493 } else if (lkp->lk_flags & LK_SHARE_NONZERO) { 494 dowakeup += shareunlock(lkp, 1); 495 COUNT(td, -1); 496 } 497 if (lkp->lk_flags & LK_WAIT_NONZERO) 498 ++dowakeup; 499 break; 500 501 default: 502 spin_unlock(&lkp->lk_spinlock); 503 panic("lockmgr: unknown locktype request %d", 504 flags & LK_TYPE_MASK); 505 /* NOTREACHED */ 506 } 507 spin_unlock(&lkp->lk_spinlock); 508 if (dowakeup) 509 wakeup(lkp); 510 return (error); 511 } 512 513 void 514 lockmgr_kernproc(struct lock *lp) 515 { 516 struct thread *td __debugvar = curthread; 517 518 if (lp->lk_lockholder != LK_KERNTHREAD) { 519 KASSERT(lp->lk_lockholder == td, 520 ("lockmgr_kernproc: lock not owned by curthread %p", td)); 521 COUNT(td, -1); 522 lp->lk_lockholder = LK_KERNTHREAD; 523 } 524 } 525 526 #if 0 527 /* 528 * Set the lock to be exclusively held. The caller is holding the lock's 529 * spinlock and the spinlock remains held on return. A panic will occur 530 * if the lock cannot be set to exclusive. 531 */ 532 void 533 lockmgr_setexclusive_interlocked(struct lock *lkp) 534 { 535 thread_t td = curthread; 536 537 KKASSERT((lkp->lk_flags & (LK_HAVE_EXCL|LK_SHARE_NONZERO)) == 0); 538 KKASSERT(lkp->lk_exclusivecount == 0); 539 lkp->lk_flags |= LK_HAVE_EXCL; 540 lkp->lk_lockholder = td; 541 lkp->lk_exclusivecount = 1; 542 COUNT(td, 1); 543 } 544 545 /* 546 * Clear the caller's exclusive lock. The caller is holding the lock's 547 * spinlock. THIS FUNCTION WILL UNLOCK THE SPINLOCK. 548 * 549 * A panic will occur if the caller does not hold the lock. 550 */ 551 void 552 lockmgr_clrexclusive_interlocked(struct lock *lkp) 553 { 554 thread_t td __debugvar = curthread; 555 int dowakeup = 0; 556 557 KKASSERT((lkp->lk_flags & LK_HAVE_EXCL) && lkp->lk_exclusivecount == 1 558 && lkp->lk_lockholder == td); 559 lkp->lk_lockholder = LK_NOTHREAD; 560 lkp->lk_flags &= ~LK_HAVE_EXCL; 561 lkp->lk_exclusivecount = 0; 562 if (lkp->lk_flags & LK_WAIT_NONZERO) 563 dowakeup = 1; 564 COUNT(td, -1); 565 spin_unlock(&lkp->lk_spinlock); 566 if (dowakeup) 567 wakeup((void *)lkp); 568 } 569 570 #endif 571 572 /* 573 * Initialize a lock; required before use. 574 */ 575 void 576 lockinit(struct lock *lkp, char *wmesg, int timo, int flags) 577 { 578 spin_init(&lkp->lk_spinlock); 579 lkp->lk_flags = (flags & LK_EXTFLG_MASK); 580 lkp->lk_sharecount = 0; 581 lkp->lk_waitcount = 0; 582 lkp->lk_exclusivecount = 0; 583 lkp->lk_wmesg = wmesg; 584 lkp->lk_timo = timo; 585 lkp->lk_lockholder = LK_NOTHREAD; 586 } 587 588 /* 589 * Reinitialize a lock that is being reused for a different purpose, but 590 * which may have pending (blocked) threads sitting on it. The caller 591 * must already hold the interlock. 592 */ 593 void 594 lockreinit(struct lock *lkp, char *wmesg, int timo, int flags) 595 { 596 spin_lock(&lkp->lk_spinlock); 597 lkp->lk_flags = (lkp->lk_flags & ~LK_EXTFLG_MASK) | 598 (flags & LK_EXTFLG_MASK); 599 lkp->lk_wmesg = wmesg; 600 lkp->lk_timo = timo; 601 spin_unlock(&lkp->lk_spinlock); 602 } 603 604 /* 605 * Requires that the caller is the exclusive owner of this lock. 606 */ 607 void 608 lockuninit(struct lock *l) 609 { 610 /* 611 * At this point we should have removed all the references to this lock 612 * so there can't be anyone waiting on it. 613 */ 614 KKASSERT(l->lk_waitcount == 0); 615 616 spin_uninit(&l->lk_spinlock); 617 } 618 619 /* 620 * Determine the status of a lock. 621 */ 622 int 623 lockstatus(struct lock *lkp, struct thread *td) 624 { 625 int lock_type = 0; 626 627 spin_lock(&lkp->lk_spinlock); 628 if (lkp->lk_exclusivecount != 0) { 629 if (td == NULL || lkp->lk_lockholder == td) 630 lock_type = LK_EXCLUSIVE; 631 else 632 lock_type = LK_EXCLOTHER; 633 } else if (lkp->lk_sharecount != 0) { 634 lock_type = LK_SHARED; 635 } 636 spin_unlock(&lkp->lk_spinlock); 637 return (lock_type); 638 } 639 640 /* 641 * Return non-zero if the caller owns the lock shared or exclusive. 642 * We can only guess re: shared locks. 643 */ 644 int 645 lockowned(struct lock *lkp) 646 { 647 thread_t td = curthread; 648 649 if (lkp->lk_exclusivecount) 650 return(lkp->lk_lockholder == td); 651 return(lkp->lk_sharecount != 0); 652 } 653 654 /* 655 * Determine the number of holders of a lock. 656 * 657 * The non-blocking version can usually be used for assertions. 658 */ 659 int 660 lockcount(struct lock *lkp) 661 { 662 int count; 663 664 spin_lock(&lkp->lk_spinlock); 665 count = lkp->lk_exclusivecount + lkp->lk_sharecount; 666 spin_unlock(&lkp->lk_spinlock); 667 return (count); 668 } 669 670 int 671 lockcountnb(struct lock *lkp) 672 { 673 return (lkp->lk_exclusivecount + lkp->lk_sharecount); 674 } 675 676 /* 677 * Print out information about state of a lock. Used by VOP_PRINT 678 * routines to display status about contained locks. 679 */ 680 void 681 lockmgr_printinfo(struct lock *lkp) 682 { 683 struct thread *td = lkp->lk_lockholder; 684 struct proc *p; 685 686 if (td && td != LK_KERNTHREAD && td != LK_NOTHREAD) 687 p = td->td_proc; 688 else 689 p = NULL; 690 691 if (lkp->lk_sharecount) 692 kprintf(" lock type %s: SHARED (count %d)", lkp->lk_wmesg, 693 lkp->lk_sharecount); 694 else if (lkp->lk_flags & LK_HAVE_EXCL) 695 kprintf(" lock type %s: EXCL (count %d) by td %p pid %d", 696 lkp->lk_wmesg, lkp->lk_exclusivecount, td, 697 p ? p->p_pid : -99); 698 if (lkp->lk_waitcount > 0) 699 kprintf(" with %d pending", lkp->lk_waitcount); 700 } 701 702