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 /* 200 * So sue me, I'm too tired. 201 */ 202 if (spin_trylock(&lkp->lk_spinlock) == FALSE) { 203 if (flags & LK_NOSPINWAIT) 204 return(EBUSY); 205 spin_lock(&lkp->lk_spinlock); 206 } 207 208 extflags = (flags | lkp->lk_flags) & LK_EXTFLG_MASK; 209 td = curthread; 210 211 switch (flags & LK_TYPE_MASK) { 212 case LK_SHARED: 213 /* 214 * If we are not the exclusive lock holder, we have to block 215 * while there is an exclusive lock holder or while an 216 * exclusive lock request or upgrade request is in progress. 217 * 218 * However, if TDF_DEADLKTREAT is set, we override exclusive 219 * lock requests or upgrade requests ( but not the exclusive 220 * lock itself ). 221 */ 222 if (lkp->lk_lockholder != td) { 223 if (td->td_flags & TDF_DEADLKTREAT) { 224 error = acquire( 225 lkp, 226 extflags, 227 LK_HAVE_EXCL 228 ); 229 } else { 230 error = acquire( 231 lkp, 232 extflags, 233 LK_HAVE_EXCL | LK_WANT_EXCL | 234 LK_WANT_UPGRADE 235 ); 236 } 237 if (error) 238 break; 239 sharelock(lkp, 1); 240 COUNT(td, 1); 241 break; 242 } 243 /* 244 * We hold an exclusive lock, so downgrade it to shared. 245 * An alternative would be to fail with EDEADLK. 246 */ 247 sharelock(lkp, 1); 248 COUNT(td, 1); 249 /* fall into downgrade */ 250 251 case LK_DOWNGRADE: 252 if (lkp->lk_lockholder != td || lkp->lk_exclusivecount == 0) { 253 spin_unlock(&lkp->lk_spinlock); 254 panic("lockmgr: not holding exclusive lock"); 255 } 256 257 #ifdef DEBUG_LOCKS 258 for (i = 0; i < LOCKMGR_DEBUG_ARRAY_SIZE; i++) { 259 if (td->td_lockmgr_stack[i] == lkp && 260 td->td_lockmgr_stack_id[i] > 0 261 ) { 262 td->td_lockmgr_stack_id[i]--; 263 break; 264 } 265 } 266 #endif 267 268 sharelock(lkp, lkp->lk_exclusivecount); 269 lkp->lk_exclusivecount = 0; 270 lkp->lk_flags &= ~LK_HAVE_EXCL; 271 lkp->lk_lockholder = LK_NOTHREAD; 272 if (lkp->lk_waitcount) 273 dowakeup = 1; 274 break; 275 276 case LK_EXCLUPGRADE: 277 /* 278 * If another process is ahead of us to get an upgrade, 279 * then we want to fail rather than have an intervening 280 * exclusive access. 281 */ 282 if (lkp->lk_flags & LK_WANT_UPGRADE) { 283 dowakeup = shareunlock(lkp, 1); 284 COUNT(td, -1); 285 error = EBUSY; 286 break; 287 } 288 /* fall into normal upgrade */ 289 290 case LK_UPGRADE: 291 /* 292 * Upgrade a shared lock to an exclusive one. If another 293 * shared lock has already requested an upgrade to an 294 * exclusive lock, our shared lock is released and an 295 * exclusive lock is requested (which will be granted 296 * after the upgrade). If we return an error, the file 297 * will always be unlocked. 298 */ 299 if ((lkp->lk_lockholder == td) || (lkp->lk_sharecount <= 0)) { 300 spin_unlock(&lkp->lk_spinlock); 301 panic("lockmgr: upgrade exclusive lock"); 302 } 303 dowakeup += shareunlock(lkp, 1); 304 COUNT(td, -1); 305 /* 306 * If we are just polling, check to see if we will block. 307 */ 308 if ((extflags & LK_NOWAIT) && 309 ((lkp->lk_flags & LK_WANT_UPGRADE) || 310 lkp->lk_sharecount > 1)) { 311 error = EBUSY; 312 break; 313 } 314 if ((lkp->lk_flags & LK_WANT_UPGRADE) == 0) { 315 /* 316 * We are first shared lock to request an upgrade, so 317 * request upgrade and wait for the shared count to 318 * drop to zero, then take exclusive lock. 319 * 320 * Although I don't think this can occur for 321 * robustness we also wait for any exclusive locks 322 * to be released. LK_WANT_UPGRADE is supposed to 323 * prevent new exclusive locks but might not in the 324 * future. 325 */ 326 lkp->lk_flags |= LK_WANT_UPGRADE; 327 error = acquire(lkp, extflags, 328 LK_HAVE_EXCL | LK_SHARE_NONZERO); 329 lkp->lk_flags &= ~LK_WANT_UPGRADE; 330 331 if (error) 332 break; 333 lkp->lk_flags |= LK_HAVE_EXCL; 334 lkp->lk_lockholder = td; 335 if (lkp->lk_exclusivecount != 0) { 336 spin_unlock(&lkp->lk_spinlock); 337 panic("lockmgr(1): non-zero exclusive count"); 338 } 339 lkp->lk_exclusivecount = 1; 340 #if defined(DEBUG_LOCKS) 341 lkp->lk_filename = file; 342 lkp->lk_lineno = line; 343 lkp->lk_lockername = name; 344 345 for (i = 0; i < LOCKMGR_DEBUG_ARRAY_SIZE; i++) { 346 /* 347 * Recursive lockmgr path 348 */ 349 if (td->td_lockmgr_stack[i] == lkp && 350 td->td_lockmgr_stack_id[i] != 0 351 ) { 352 td->td_lockmgr_stack_id[i]++; 353 goto lkmatch2; 354 } 355 } 356 357 for (i = 0; i < LOCKMGR_DEBUG_ARRAY_SIZE; i++) { 358 /* 359 * Use new lockmgr tracking slot 360 */ 361 if (td->td_lockmgr_stack_id[i] == 0) { 362 td->td_lockmgr_stack_id[i]++; 363 td->td_lockmgr_stack[i] = lkp; 364 break; 365 } 366 } 367 lkmatch2: 368 ; 369 #endif 370 COUNT(td, 1); 371 break; 372 } 373 /* 374 * Someone else has requested upgrade. Release our shared 375 * lock, awaken upgrade requestor if we are the last shared 376 * lock, then request an exclusive lock. 377 */ 378 if ( (lkp->lk_flags & (LK_SHARE_NONZERO|LK_WAIT_NONZERO)) == 379 LK_WAIT_NONZERO) { 380 ++dowakeup; 381 } 382 /* fall into exclusive request */ 383 384 case LK_EXCLUSIVE: 385 if (lkp->lk_lockholder == td && td != LK_KERNTHREAD) { 386 /* 387 * Recursive lock. 388 */ 389 if ((extflags & (LK_NOWAIT | LK_CANRECURSE)) == 0) { 390 spin_unlock(&lkp->lk_spinlock); 391 panic("lockmgr: locking against myself"); 392 } 393 if ((extflags & LK_CANRECURSE) != 0) { 394 lkp->lk_exclusivecount++; 395 COUNT(td, 1); 396 break; 397 } 398 } 399 /* 400 * If we are just polling, check to see if we will sleep. 401 */ 402 if ((extflags & LK_NOWAIT) && 403 (lkp->lk_flags & (LK_HAVE_EXCL | LK_WANT_EXCL | 404 LK_WANT_UPGRADE | LK_SHARE_NONZERO))) { 405 error = EBUSY; 406 break; 407 } 408 /* 409 * Wait for exclusive lock holders to release and try to 410 * acquire the want_exclusive flag. 411 */ 412 error = acquire(lkp, extflags, (LK_HAVE_EXCL | LK_WANT_EXCL)); 413 if (error) 414 break; 415 lkp->lk_flags |= LK_WANT_EXCL; 416 417 /* 418 * Wait for shared locks and upgrades to finish. We can lose 419 * the race against a successful shared lock upgrade in which 420 * case LK_HAVE_EXCL will get set regardless of our 421 * acquisition of LK_WANT_EXCL, so we have to acquire 422 * LK_HAVE_EXCL here as well. 423 */ 424 error = acquire(lkp, extflags, LK_HAVE_EXCL | 425 LK_WANT_UPGRADE | 426 LK_SHARE_NONZERO); 427 lkp->lk_flags &= ~LK_WANT_EXCL; 428 if (error) 429 break; 430 lkp->lk_flags |= LK_HAVE_EXCL; 431 lkp->lk_lockholder = td; 432 if (lkp->lk_exclusivecount != 0) { 433 spin_unlock(&lkp->lk_spinlock); 434 panic("lockmgr(2): non-zero exclusive count"); 435 } 436 lkp->lk_exclusivecount = 1; 437 #if defined(DEBUG_LOCKS) 438 lkp->lk_filename = file; 439 lkp->lk_lineno = line; 440 lkp->lk_lockername = name; 441 442 for (i = 0; i < LOCKMGR_DEBUG_ARRAY_SIZE; i++) { 443 /* 444 * Recursive lockmgr path 445 */ 446 if (td->td_lockmgr_stack[i] == lkp && 447 td->td_lockmgr_stack_id[i] != 0 448 ) { 449 td->td_lockmgr_stack_id[i]++; 450 goto lkmatch1; 451 } 452 } 453 454 for (i = 0; i < LOCKMGR_DEBUG_ARRAY_SIZE; i++) { 455 /* 456 * Use new lockmgr tracking slot 457 */ 458 if (td->td_lockmgr_stack_id[i] == 0) { 459 td->td_lockmgr_stack_id[i]++; 460 td->td_lockmgr_stack[i] = lkp; 461 break; 462 } 463 } 464 lkmatch1: 465 ; 466 #endif 467 COUNT(td, 1); 468 break; 469 470 case LK_RELEASE: 471 if (lkp->lk_exclusivecount != 0) { 472 if (lkp->lk_lockholder != td && 473 lkp->lk_lockholder != LK_KERNTHREAD) { 474 spin_unlock(&lkp->lk_spinlock); 475 panic("lockmgr: pid %d, not %s thr %p/%p unlocking", 476 (td->td_proc ? td->td_proc->p_pid : -1), 477 "exclusive lock holder", 478 td, lkp->lk_lockholder); 479 } 480 if (lkp->lk_lockholder != LK_KERNTHREAD) { 481 COUNT(td, -1); 482 } 483 if (lkp->lk_exclusivecount == 1) { 484 lkp->lk_flags &= ~LK_HAVE_EXCL; 485 lkp->lk_lockholder = LK_NOTHREAD; 486 lkp->lk_exclusivecount = 0; 487 } else { 488 lkp->lk_exclusivecount--; 489 } 490 #ifdef DEBUG_LOCKS 491 for (i = 0; i < LOCKMGR_DEBUG_ARRAY_SIZE; i++) { 492 if (td->td_lockmgr_stack[i] == lkp && 493 td->td_lockmgr_stack_id[i] > 0 494 ) { 495 td->td_lockmgr_stack_id[i]--; 496 break; 497 } 498 } 499 #endif 500 } else if (lkp->lk_flags & LK_SHARE_NONZERO) { 501 dowakeup += shareunlock(lkp, 1); 502 COUNT(td, -1); 503 } 504 if (lkp->lk_flags & LK_WAIT_NONZERO) 505 ++dowakeup; 506 break; 507 508 default: 509 spin_unlock(&lkp->lk_spinlock); 510 panic("lockmgr: unknown locktype request %d", 511 flags & LK_TYPE_MASK); 512 /* NOTREACHED */ 513 } 514 spin_unlock(&lkp->lk_spinlock); 515 if (dowakeup) 516 wakeup(lkp); 517 return (error); 518 } 519 520 void 521 lockmgr_kernproc(struct lock *lp) 522 { 523 struct thread *td __debugvar = curthread; 524 525 if (lp->lk_lockholder != LK_KERNTHREAD) { 526 KASSERT(lp->lk_lockholder == td, 527 ("lockmgr_kernproc: lock not owned by curthread %p", td)); 528 COUNT(td, -1); 529 lp->lk_lockholder = LK_KERNTHREAD; 530 } 531 } 532 533 #if 0 534 /* 535 * Set the lock to be exclusively held. The caller is holding the lock's 536 * spinlock and the spinlock remains held on return. A panic will occur 537 * if the lock cannot be set to exclusive. 538 */ 539 void 540 lockmgr_setexclusive_interlocked(struct lock *lkp) 541 { 542 thread_t td = curthread; 543 544 KKASSERT((lkp->lk_flags & (LK_HAVE_EXCL|LK_SHARE_NONZERO)) == 0); 545 KKASSERT(lkp->lk_exclusivecount == 0); 546 lkp->lk_flags |= LK_HAVE_EXCL; 547 lkp->lk_lockholder = td; 548 lkp->lk_exclusivecount = 1; 549 COUNT(td, 1); 550 } 551 552 /* 553 * Clear the caller's exclusive lock. The caller is holding the lock's 554 * spinlock. THIS FUNCTION WILL UNLOCK THE SPINLOCK. 555 * 556 * A panic will occur if the caller does not hold the lock. 557 */ 558 void 559 lockmgr_clrexclusive_interlocked(struct lock *lkp) 560 { 561 thread_t td __debugvar = curthread; 562 int dowakeup = 0; 563 564 KKASSERT((lkp->lk_flags & LK_HAVE_EXCL) && lkp->lk_exclusivecount == 1 565 && lkp->lk_lockholder == td); 566 lkp->lk_lockholder = LK_NOTHREAD; 567 lkp->lk_flags &= ~LK_HAVE_EXCL; 568 lkp->lk_exclusivecount = 0; 569 if (lkp->lk_flags & LK_WAIT_NONZERO) 570 dowakeup = 1; 571 COUNT(td, -1); 572 spin_unlock(&lkp->lk_spinlock); 573 if (dowakeup) 574 wakeup((void *)lkp); 575 } 576 577 #endif 578 579 /* 580 * Initialize a lock; required before use. 581 */ 582 void 583 lockinit(struct lock *lkp, char *wmesg, int timo, int flags) 584 { 585 spin_init(&lkp->lk_spinlock); 586 lkp->lk_flags = (flags & LK_EXTFLG_MASK); 587 lkp->lk_sharecount = 0; 588 lkp->lk_waitcount = 0; 589 lkp->lk_exclusivecount = 0; 590 lkp->lk_wmesg = wmesg; 591 lkp->lk_timo = timo; 592 lkp->lk_lockholder = LK_NOTHREAD; 593 } 594 595 /* 596 * Reinitialize a lock that is being reused for a different purpose, but 597 * which may have pending (blocked) threads sitting on it. The caller 598 * must already hold the interlock. 599 */ 600 void 601 lockreinit(struct lock *lkp, char *wmesg, int timo, int flags) 602 { 603 spin_lock(&lkp->lk_spinlock); 604 lkp->lk_flags = (lkp->lk_flags & ~LK_EXTFLG_MASK) | 605 (flags & LK_EXTFLG_MASK); 606 lkp->lk_wmesg = wmesg; 607 lkp->lk_timo = timo; 608 spin_unlock(&lkp->lk_spinlock); 609 } 610 611 /* 612 * Requires that the caller is the exclusive owner of this lock. 613 */ 614 void 615 lockuninit(struct lock *l) 616 { 617 /* 618 * At this point we should have removed all the references to this lock 619 * so there can't be anyone waiting on it. 620 */ 621 KKASSERT(l->lk_waitcount == 0); 622 623 spin_uninit(&l->lk_spinlock); 624 } 625 626 /* 627 * Determine the status of a lock. 628 */ 629 int 630 lockstatus(struct lock *lkp, struct thread *td) 631 { 632 int lock_type = 0; 633 634 spin_lock(&lkp->lk_spinlock); 635 if (lkp->lk_exclusivecount != 0) { 636 if (td == NULL || lkp->lk_lockholder == td) 637 lock_type = LK_EXCLUSIVE; 638 else 639 lock_type = LK_EXCLOTHER; 640 } else if (lkp->lk_sharecount != 0) { 641 lock_type = LK_SHARED; 642 } 643 spin_unlock(&lkp->lk_spinlock); 644 return (lock_type); 645 } 646 647 /* 648 * Return non-zero if the caller owns the lock shared or exclusive. 649 * We can only guess re: shared locks. 650 */ 651 int 652 lockowned(struct lock *lkp) 653 { 654 thread_t td = curthread; 655 656 if (lkp->lk_exclusivecount) 657 return(lkp->lk_lockholder == td); 658 return(lkp->lk_sharecount != 0); 659 } 660 661 /* 662 * Determine the number of holders of a lock. 663 * 664 * The non-blocking version can usually be used for assertions. 665 */ 666 int 667 lockcount(struct lock *lkp) 668 { 669 int count; 670 671 spin_lock(&lkp->lk_spinlock); 672 count = lkp->lk_exclusivecount + lkp->lk_sharecount; 673 spin_unlock(&lkp->lk_spinlock); 674 return (count); 675 } 676 677 int 678 lockcountnb(struct lock *lkp) 679 { 680 return (lkp->lk_exclusivecount + lkp->lk_sharecount); 681 } 682 683 /* 684 * Print out information about state of a lock. Used by VOP_PRINT 685 * routines to display status about contained locks. 686 */ 687 void 688 lockmgr_printinfo(struct lock *lkp) 689 { 690 struct thread *td = lkp->lk_lockholder; 691 struct proc *p; 692 693 if (td && td != LK_KERNTHREAD && td != LK_NOTHREAD) 694 p = td->td_proc; 695 else 696 p = NULL; 697 698 if (lkp->lk_sharecount) 699 kprintf(" lock type %s: SHARED (count %d)", lkp->lk_wmesg, 700 lkp->lk_sharecount); 701 else if (lkp->lk_flags & LK_HAVE_EXCL) 702 kprintf(" lock type %s: EXCL (count %d) by td %p pid %d", 703 lkp->lk_wmesg, lkp->lk_exclusivecount, td, 704 p ? p->p_pid : -99); 705 if (lkp->lk_waitcount > 0) 706 kprintf(" with %d pending", lkp->lk_waitcount); 707 } 708 709