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 { 85 lkp->lk_flags |= LK_SHARE_NONZERO; 86 lkp->lk_sharecount += incr; 87 } 88 89 static LOCK_INLINE int 90 shareunlock(struct lock *lkp, int decr) 91 { 92 int dowakeup = 0; 93 94 KASSERT(lkp->lk_sharecount >= decr, ("shareunlock: count < decr")); 95 96 if (lkp->lk_sharecount == decr) { 97 lkp->lk_flags &= ~LK_SHARE_NONZERO; 98 if (lkp->lk_flags & (LK_WANT_UPGRADE | LK_WANT_EXCL)) { 99 dowakeup = 1; 100 } 101 lkp->lk_sharecount = 0; 102 } else { 103 lkp->lk_sharecount -= decr; 104 } 105 return(dowakeup); 106 } 107 108 /* 109 * lock acquisition helper routine. Called with the lock's spinlock held. 110 */ 111 static int 112 acquire(struct lock *lkp, int extflags, int wanted) 113 { 114 int error; 115 116 if ((extflags & LK_NOWAIT) && (lkp->lk_flags & wanted)) { 117 return EBUSY; 118 } 119 120 while ((lkp->lk_flags & wanted) != 0) { 121 lkp->lk_flags |= LK_WAIT_NONZERO; 122 lkp->lk_waitcount++; 123 124 /* 125 * Atomic spinlock release/sleep/reacquire. 126 */ 127 error = ssleep(lkp, &lkp->lk_spinlock, 128 ((extflags & LK_PCATCH) ? PCATCH : 0), 129 lkp->lk_wmesg, 130 ((extflags & LK_TIMELOCK) ? lkp->lk_timo : 0)); 131 if (lkp->lk_waitcount == 1) { 132 lkp->lk_flags &= ~LK_WAIT_NONZERO; 133 lkp->lk_waitcount = 0; 134 } else { 135 lkp->lk_waitcount--; 136 } 137 if (error) 138 return error; 139 if (extflags & LK_SLEEPFAIL) 140 return ENOLCK; 141 } 142 return 0; 143 } 144 145 /* 146 * Set, change, or release a lock. 147 * 148 * Shared requests increment the shared count. Exclusive requests set the 149 * LK_WANT_EXCL flag (preventing further shared locks), and wait for already 150 * accepted shared locks and shared-to-exclusive upgrades to go away. 151 * 152 * A spinlock is held for most of the procedure. We must not do anything 153 * fancy while holding the spinlock. 154 */ 155 int 156 #ifndef DEBUG_LOCKS 157 lockmgr(struct lock *lkp, u_int flags) 158 #else 159 debuglockmgr(struct lock *lkp, u_int flags, 160 const char *name, const char *file, int line) 161 #endif 162 { 163 thread_t td; 164 int error; 165 int extflags; 166 int dowakeup; 167 #ifdef DEBUG_LOCKS 168 int i; 169 #endif 170 171 error = 0; 172 dowakeup = 0; 173 174 if (mycpu->gd_intr_nesting_level && 175 (flags & LK_NOWAIT) == 0 && 176 (flags & LK_TYPE_MASK) != LK_RELEASE && 177 panic_cpu_gd != mycpu 178 ) { 179 180 #ifndef DEBUG_LOCKS 181 panic("lockmgr %s from %p: called from interrupt, ipi, " 182 "or hard code section", 183 lkp->lk_wmesg, ((int **)&lkp)[-1]); 184 #else 185 panic("lockmgr %s from %s:%d: called from interrupt, ipi, " 186 "or hard code section", 187 lkp->lk_wmesg, file, line); 188 #endif 189 } 190 191 #ifdef DEBUG_LOCKS 192 if (mycpu->gd_spinlocks && ((flags & LK_NOWAIT) == 0)) { 193 panic("lockmgr %s from %s:%d: called with %d spinlocks held", 194 lkp->lk_wmesg, file, line, mycpu->gd_spinlocks); 195 } 196 #endif 197 198 spin_lock(&lkp->lk_spinlock); 199 200 extflags = (flags | lkp->lk_flags) & LK_EXTFLG_MASK; 201 td = curthread; 202 203 switch (flags & LK_TYPE_MASK) { 204 case LK_SHARED: 205 /* 206 * If we are not the exclusive lock holder, we have to block 207 * while there is an exclusive lock holder or while an 208 * exclusive lock request or upgrade request is in progress. 209 * 210 * However, if TDF_DEADLKTREAT is set, we override exclusive 211 * lock requests or upgrade requests ( but not the exclusive 212 * lock itself ). 213 */ 214 if (lkp->lk_lockholder != td) { 215 if (td->td_flags & TDF_DEADLKTREAT) { 216 error = acquire( 217 lkp, 218 extflags, 219 LK_HAVE_EXCL 220 ); 221 } else { 222 error = acquire( 223 lkp, 224 extflags, 225 LK_HAVE_EXCL | LK_WANT_EXCL | 226 LK_WANT_UPGRADE 227 ); 228 } 229 if (error) 230 break; 231 sharelock(lkp, 1); 232 COUNT(td, 1); 233 break; 234 } 235 236 /* 237 * If we already hold an exclusive lock we bump the 238 * exclusive count instead of downgrading to a shared 239 * lock. 240 * 241 * WARNING! The old FreeBSD behavior was to downgrade, 242 * but this creates a problem when recursions 243 * return to the caller and the caller expects 244 * its original exclusive lock to remain exclusively 245 * locked. 246 */ 247 if (extflags & LK_CANRECURSE) { 248 lkp->lk_exclusivecount++; 249 COUNT(td, 1); 250 break; 251 } 252 if (extflags & LK_NOWAIT) { 253 error = EBUSY; 254 break; 255 } 256 spin_unlock(&lkp->lk_spinlock); 257 panic("lockmgr: locking against myself"); 258 #if 0 259 /* 260 * old code queued a shared lock request fell into 261 * a downgrade. 262 */ 263 sharelock(lkp, 1); 264 COUNT(td, 1); 265 /* fall into downgrade */ 266 #endif 267 268 case LK_DOWNGRADE: 269 if (lkp->lk_lockholder != td || lkp->lk_exclusivecount == 0) { 270 spin_unlock(&lkp->lk_spinlock); 271 panic("lockmgr: not holding exclusive lock"); 272 } 273 274 #ifdef DEBUG_LOCKS 275 for (i = 0; i < LOCKMGR_DEBUG_ARRAY_SIZE; i++) { 276 if (td->td_lockmgr_stack[i] == lkp && 277 td->td_lockmgr_stack_id[i] > 0 278 ) { 279 td->td_lockmgr_stack_id[i]--; 280 break; 281 } 282 } 283 #endif 284 285 sharelock(lkp, lkp->lk_exclusivecount); 286 lkp->lk_exclusivecount = 0; 287 lkp->lk_flags &= ~LK_HAVE_EXCL; 288 lkp->lk_lockholder = LK_NOTHREAD; 289 if (lkp->lk_waitcount) 290 dowakeup = 1; 291 break; 292 293 case LK_EXCLUPGRADE: 294 /* 295 * If another process is ahead of us to get an upgrade, 296 * then we want to fail rather than have an intervening 297 * exclusive access. 298 */ 299 if (lkp->lk_flags & LK_WANT_UPGRADE) { 300 dowakeup = shareunlock(lkp, 1); 301 COUNT(td, -1); 302 error = EBUSY; 303 break; 304 } 305 /* fall into normal upgrade */ 306 307 case LK_UPGRADE: 308 /* 309 * Upgrade a shared lock to an exclusive one. If another 310 * shared lock has already requested an upgrade to an 311 * exclusive lock, our shared lock is released and an 312 * exclusive lock is requested (which will be granted 313 * after the upgrade). If we return an error, the file 314 * will always be unlocked. 315 */ 316 if ((lkp->lk_lockholder == td) || (lkp->lk_sharecount <= 0)) { 317 spin_unlock(&lkp->lk_spinlock); 318 panic("lockmgr: upgrade exclusive lock"); 319 } 320 dowakeup += shareunlock(lkp, 1); 321 COUNT(td, -1); 322 /* 323 * If we are just polling, check to see if we will block. 324 */ 325 if ((extflags & LK_NOWAIT) && 326 ((lkp->lk_flags & LK_WANT_UPGRADE) || 327 lkp->lk_sharecount > 1)) { 328 error = EBUSY; 329 break; 330 } 331 if ((lkp->lk_flags & LK_WANT_UPGRADE) == 0) { 332 /* 333 * We are first shared lock to request an upgrade, so 334 * request upgrade and wait for the shared count to 335 * drop to zero, then take exclusive lock. 336 * 337 * Although I don't think this can occur for 338 * robustness we also wait for any exclusive locks 339 * to be released. LK_WANT_UPGRADE is supposed to 340 * prevent new exclusive locks but might not in the 341 * future. 342 */ 343 lkp->lk_flags |= LK_WANT_UPGRADE; 344 error = acquire(lkp, extflags, 345 LK_HAVE_EXCL | LK_SHARE_NONZERO); 346 lkp->lk_flags &= ~LK_WANT_UPGRADE; 347 348 if (error) 349 break; 350 lkp->lk_flags |= LK_HAVE_EXCL; 351 lkp->lk_lockholder = td; 352 if (lkp->lk_exclusivecount != 0) { 353 spin_unlock(&lkp->lk_spinlock); 354 panic("lockmgr(1): non-zero exclusive count"); 355 } 356 lkp->lk_exclusivecount = 1; 357 #if defined(DEBUG_LOCKS) 358 lkp->lk_filename = file; 359 lkp->lk_lineno = line; 360 lkp->lk_lockername = name; 361 362 for (i = 0; i < LOCKMGR_DEBUG_ARRAY_SIZE; i++) { 363 /* 364 * Recursive lockmgr path 365 */ 366 if (td->td_lockmgr_stack[i] == lkp && 367 td->td_lockmgr_stack_id[i] != 0 368 ) { 369 td->td_lockmgr_stack_id[i]++; 370 goto lkmatch2; 371 } 372 } 373 374 for (i = 0; i < LOCKMGR_DEBUG_ARRAY_SIZE; i++) { 375 /* 376 * Use new lockmgr tracking slot 377 */ 378 if (td->td_lockmgr_stack_id[i] == 0) { 379 td->td_lockmgr_stack_id[i]++; 380 td->td_lockmgr_stack[i] = lkp; 381 break; 382 } 383 } 384 lkmatch2: 385 ; 386 #endif 387 COUNT(td, 1); 388 break; 389 } 390 /* 391 * Someone else has requested upgrade. Release our shared 392 * lock, awaken upgrade requestor if we are the last shared 393 * lock, then request an exclusive lock. 394 */ 395 if ((lkp->lk_flags & (LK_SHARE_NONZERO|LK_WAIT_NONZERO)) == 396 LK_WAIT_NONZERO) { 397 ++dowakeup; 398 } 399 /* fall into exclusive request */ 400 401 case LK_EXCLUSIVE: 402 if (lkp->lk_lockholder == td && td != LK_KERNTHREAD) { 403 /* 404 * Recursive lock. 405 */ 406 if ((extflags & (LK_NOWAIT | LK_CANRECURSE)) == 0) { 407 spin_unlock(&lkp->lk_spinlock); 408 panic("lockmgr: locking against myself"); 409 } 410 if ((extflags & LK_CANRECURSE) != 0) { 411 lkp->lk_exclusivecount++; 412 COUNT(td, 1); 413 break; 414 } 415 } 416 /* 417 * If we are just polling, check to see if we will sleep. 418 */ 419 if ((extflags & LK_NOWAIT) && 420 (lkp->lk_flags & (LK_HAVE_EXCL | LK_WANT_EXCL | 421 LK_WANT_UPGRADE | LK_SHARE_NONZERO))) { 422 error = EBUSY; 423 break; 424 } 425 /* 426 * Wait for exclusive lock holders to release and try to 427 * acquire the want_exclusive flag. 428 */ 429 error = acquire(lkp, extflags, (LK_HAVE_EXCL | LK_WANT_EXCL)); 430 if (error) 431 break; 432 lkp->lk_flags |= LK_WANT_EXCL; 433 434 /* 435 * Wait for shared locks and upgrades to finish. We can lose 436 * the race against a successful shared lock upgrade in which 437 * case LK_HAVE_EXCL will get set regardless of our 438 * acquisition of LK_WANT_EXCL, so we have to acquire 439 * LK_HAVE_EXCL here as well. 440 */ 441 error = acquire(lkp, extflags, LK_HAVE_EXCL | 442 LK_WANT_UPGRADE | 443 LK_SHARE_NONZERO); 444 lkp->lk_flags &= ~LK_WANT_EXCL; 445 if (error) 446 break; 447 lkp->lk_flags |= LK_HAVE_EXCL; 448 lkp->lk_lockholder = td; 449 if (lkp->lk_exclusivecount != 0) { 450 spin_unlock(&lkp->lk_spinlock); 451 panic("lockmgr(2): non-zero exclusive count"); 452 } 453 lkp->lk_exclusivecount = 1; 454 #if defined(DEBUG_LOCKS) 455 lkp->lk_filename = file; 456 lkp->lk_lineno = line; 457 lkp->lk_lockername = name; 458 459 for (i = 0; i < LOCKMGR_DEBUG_ARRAY_SIZE; i++) { 460 /* 461 * Recursive lockmgr path 462 */ 463 if (td->td_lockmgr_stack[i] == lkp && 464 td->td_lockmgr_stack_id[i] != 0 465 ) { 466 td->td_lockmgr_stack_id[i]++; 467 goto lkmatch1; 468 } 469 } 470 471 for (i = 0; i < LOCKMGR_DEBUG_ARRAY_SIZE; i++) { 472 /* 473 * Use new lockmgr tracking slot 474 */ 475 if (td->td_lockmgr_stack_id[i] == 0) { 476 td->td_lockmgr_stack_id[i]++; 477 td->td_lockmgr_stack[i] = lkp; 478 break; 479 } 480 } 481 lkmatch1: 482 ; 483 #endif 484 COUNT(td, 1); 485 break; 486 487 case LK_RELEASE: 488 if (lkp->lk_exclusivecount != 0) { 489 if (lkp->lk_lockholder != td && 490 lkp->lk_lockholder != LK_KERNTHREAD) { 491 spin_unlock(&lkp->lk_spinlock); 492 panic("lockmgr: pid %d, not %s thr %p/%p unlocking", 493 (td->td_proc ? td->td_proc->p_pid : -1), 494 "exclusive lock holder", 495 td, lkp->lk_lockholder); 496 } 497 if (lkp->lk_lockholder != LK_KERNTHREAD) { 498 COUNT(td, -1); 499 } 500 if (lkp->lk_exclusivecount == 1) { 501 lkp->lk_flags &= ~LK_HAVE_EXCL; 502 lkp->lk_lockholder = LK_NOTHREAD; 503 lkp->lk_exclusivecount = 0; 504 } else { 505 lkp->lk_exclusivecount--; 506 } 507 #ifdef DEBUG_LOCKS 508 for (i = 0; i < LOCKMGR_DEBUG_ARRAY_SIZE; i++) { 509 if (td->td_lockmgr_stack[i] == lkp && 510 td->td_lockmgr_stack_id[i] > 0 511 ) { 512 td->td_lockmgr_stack_id[i]--; 513 lkp->lk_filename = file; 514 lkp->lk_lineno = line; 515 break; 516 } 517 } 518 #endif 519 } else if (lkp->lk_flags & LK_SHARE_NONZERO) { 520 dowakeup += shareunlock(lkp, 1); 521 COUNT(td, -1); 522 } else { 523 panic("lockmgr: LK_RELEASE: no lock held"); 524 } 525 if (lkp->lk_flags & LK_WAIT_NONZERO) 526 ++dowakeup; 527 break; 528 529 default: 530 spin_unlock(&lkp->lk_spinlock); 531 panic("lockmgr: unknown locktype request %d", 532 flags & LK_TYPE_MASK); 533 /* NOTREACHED */ 534 } 535 spin_unlock(&lkp->lk_spinlock); 536 if (dowakeup) 537 wakeup(lkp); 538 return (error); 539 } 540 541 void 542 lockmgr_kernproc(struct lock *lp) 543 { 544 struct thread *td __debugvar = curthread; 545 546 if (lp->lk_lockholder != LK_KERNTHREAD) { 547 KASSERT(lp->lk_lockholder == td, 548 ("lockmgr_kernproc: lock not owned by curthread %p", td)); 549 COUNT(td, -1); 550 lp->lk_lockholder = LK_KERNTHREAD; 551 } 552 } 553 554 #if 0 555 /* 556 * Set the lock to be exclusively held. The caller is holding the lock's 557 * spinlock and the spinlock remains held on return. A panic will occur 558 * if the lock cannot be set to exclusive. 559 * 560 * XXX not only unused but these functions also break EXCLUPGRADE's 561 * atomicy. 562 */ 563 void 564 lockmgr_setexclusive_interlocked(struct lock *lkp) 565 { 566 thread_t td = curthread; 567 568 KKASSERT((lkp->lk_flags & (LK_HAVE_EXCL|LK_SHARE_NONZERO)) == 0); 569 KKASSERT(lkp->lk_exclusivecount == 0); 570 lkp->lk_flags |= LK_HAVE_EXCL; 571 lkp->lk_lockholder = td; 572 lkp->lk_exclusivecount = 1; 573 COUNT(td, 1); 574 } 575 576 /* 577 * Clear the caller's exclusive lock. The caller is holding the lock's 578 * spinlock. THIS FUNCTION WILL UNLOCK THE SPINLOCK. 579 * 580 * A panic will occur if the caller does not hold the lock. 581 */ 582 void 583 lockmgr_clrexclusive_interlocked(struct lock *lkp) 584 { 585 thread_t td __debugvar = curthread; 586 int dowakeup = 0; 587 588 KKASSERT((lkp->lk_flags & LK_HAVE_EXCL) && lkp->lk_exclusivecount == 1 589 && lkp->lk_lockholder == td); 590 lkp->lk_lockholder = LK_NOTHREAD; 591 lkp->lk_flags &= ~LK_HAVE_EXCL; 592 lkp->lk_exclusivecount = 0; 593 if (lkp->lk_flags & LK_WAIT_NONZERO) 594 dowakeup = 1; 595 COUNT(td, -1); 596 spin_unlock(&lkp->lk_spinlock); 597 if (dowakeup) 598 wakeup((void *)lkp); 599 } 600 601 #endif 602 603 /* 604 * Initialize a lock; required before use. 605 */ 606 void 607 lockinit(struct lock *lkp, const char *wmesg, int timo, int flags) 608 { 609 spin_init(&lkp->lk_spinlock); 610 lkp->lk_flags = (flags & LK_EXTFLG_MASK); 611 lkp->lk_sharecount = 0; 612 lkp->lk_waitcount = 0; 613 lkp->lk_exclusivecount = 0; 614 lkp->lk_wmesg = wmesg; 615 lkp->lk_timo = timo; 616 lkp->lk_lockholder = LK_NOTHREAD; 617 } 618 619 /* 620 * Reinitialize a lock that is being reused for a different purpose, but 621 * which may have pending (blocked) threads sitting on it. The caller 622 * must already hold the interlock. 623 */ 624 void 625 lockreinit(struct lock *lkp, const char *wmesg, int timo, int flags) 626 { 627 spin_lock(&lkp->lk_spinlock); 628 lkp->lk_flags = (lkp->lk_flags & ~LK_EXTFLG_MASK) | 629 (flags & LK_EXTFLG_MASK); 630 lkp->lk_wmesg = wmesg; 631 lkp->lk_timo = timo; 632 spin_unlock(&lkp->lk_spinlock); 633 } 634 635 /* 636 * Requires that the caller is the exclusive owner of this lock. 637 */ 638 void 639 lockuninit(struct lock *l) 640 { 641 /* 642 * At this point we should have removed all the references to this lock 643 * so there can't be anyone waiting on it. 644 */ 645 KKASSERT(l->lk_waitcount == 0); 646 647 spin_uninit(&l->lk_spinlock); 648 } 649 650 /* 651 * Determine the status of a lock. 652 */ 653 int 654 lockstatus(struct lock *lkp, struct thread *td) 655 { 656 int lock_type = 0; 657 658 spin_lock(&lkp->lk_spinlock); 659 if (lkp->lk_exclusivecount != 0) { 660 if (td == NULL || lkp->lk_lockholder == td) 661 lock_type = LK_EXCLUSIVE; 662 else 663 lock_type = LK_EXCLOTHER; 664 } else if (lkp->lk_sharecount != 0) { 665 lock_type = LK_SHARED; 666 } 667 spin_unlock(&lkp->lk_spinlock); 668 return (lock_type); 669 } 670 671 /* 672 * Return non-zero if the caller owns the lock shared or exclusive. 673 * We can only guess re: shared locks. 674 */ 675 int 676 lockowned(struct lock *lkp) 677 { 678 thread_t td = curthread; 679 680 if (lkp->lk_exclusivecount) 681 return(lkp->lk_lockholder == td); 682 return(lkp->lk_sharecount != 0); 683 } 684 685 /* 686 * Determine the number of holders of a lock. 687 * 688 * The non-blocking version can usually be used for assertions. 689 */ 690 int 691 lockcount(struct lock *lkp) 692 { 693 int count; 694 695 spin_lock(&lkp->lk_spinlock); 696 count = lkp->lk_exclusivecount + lkp->lk_sharecount; 697 spin_unlock(&lkp->lk_spinlock); 698 return (count); 699 } 700 701 int 702 lockcountnb(struct lock *lkp) 703 { 704 return (lkp->lk_exclusivecount + lkp->lk_sharecount); 705 } 706 707 /* 708 * Print out information about state of a lock. Used by VOP_PRINT 709 * routines to display status about contained locks. 710 */ 711 void 712 lockmgr_printinfo(struct lock *lkp) 713 { 714 struct thread *td = lkp->lk_lockholder; 715 struct proc *p; 716 717 if (td && td != LK_KERNTHREAD && td != LK_NOTHREAD) 718 p = td->td_proc; 719 else 720 p = NULL; 721 722 if (lkp->lk_sharecount) 723 kprintf(" lock type %s: SHARED (count %d)", lkp->lk_wmesg, 724 lkp->lk_sharecount); 725 else if (lkp->lk_flags & LK_HAVE_EXCL) 726 kprintf(" lock type %s: EXCL (count %d) by td %p pid %d", 727 lkp->lk_wmesg, lkp->lk_exclusivecount, td, 728 p ? p->p_pid : -99); 729 if (lkp->lk_waitcount > 0) 730 kprintf(" with %d pending", lkp->lk_waitcount); 731 } 732 733 void 734 lock_sysinit(struct lock_args *arg) 735 { 736 lockinit(arg->la_lock, arg->la_desc, 0, arg->la_flags); 737 } 738