kern_lock.c revision 132587
1112918Sjeff/* 2112918Sjeff * Copyright (c) 1995 3112918Sjeff * The Regents of the University of California. All rights reserved. 4112918Sjeff * 5112918Sjeff * Copyright (C) 1997 6112918Sjeff * John S. Dyson. All rights reserved. 7112918Sjeff * 8112918Sjeff * This code contains ideas from software contributed to Berkeley by 9112918Sjeff * Avadis Tevanian, Jr., Michael Wayne Young, and the Mach Operating 10112918Sjeff * System project at Carnegie-Mellon University. 11112918Sjeff * 12112918Sjeff * Redistribution and use in source and binary forms, with or without 13112918Sjeff * modification, are permitted provided that the following conditions 14112918Sjeff * are met: 15112918Sjeff * 1. Redistributions of source code must retain the above copyright 16112918Sjeff * notice, this list of conditions and the following disclaimer. 17112918Sjeff * 2. Redistributions in binary form must reproduce the above copyright 18112918Sjeff * notice, this list of conditions and the following disclaimer in the 19112918Sjeff * documentation and/or other materials provided with the distribution. 20112918Sjeff * 3. All advertising materials mentioning features or use of this software 21112918Sjeff * must display the following acknowledgement: 22112918Sjeff * This product includes software developed by the University of 23112918Sjeff * California, Berkeley and its contributors. 24112918Sjeff * 4. Neither the name of the University nor the names of its contributors 25112918Sjeff * may be used to endorse or promote products derived from this software 26112918Sjeff * without specific prior written permission. 27112918Sjeff * 28112918Sjeff * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 29112918Sjeff * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 30112918Sjeff * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 31112918Sjeff * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 32112918Sjeff * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 33112918Sjeff * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 34144518Sdavidxu * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 35157457Sdavidxu * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 36112918Sjeff * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 37112918Sjeff * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 38112918Sjeff * SUCH DAMAGE. 39112918Sjeff * 40112918Sjeff * @(#)kern_lock.c 8.18 (Berkeley) 5/21/95 41157457Sdavidxu */ 42144518Sdavidxu 43112918Sjeff#include <sys/cdefs.h> 44112918Sjeff__FBSDID("$FreeBSD: head/sys/kern/kern_lock.c 132587 2004-07-23 20:12:56Z rwatson $"); 45112918Sjeff 46144518Sdavidxu#include <sys/param.h> 47112918Sjeff#include <sys/kernel.h> 48112918Sjeff#include <sys/ktr.h> 49112918Sjeff#include <sys/lock.h> 50112918Sjeff#include <sys/lockmgr.h> 51112918Sjeff#include <sys/mutex.h> 52112918Sjeff#include <sys/proc.h> 53112918Sjeff#include <sys/systm.h> 54112918Sjeff 55144518Sdavidxu/* 56112918Sjeff * Locking primitives implementation. 57144518Sdavidxu * Locks provide shared/exclusive sychronization. 58144518Sdavidxu */ 59112918Sjeff 60144518Sdavidxu#define LOCK_WAIT_TIME 100 61144518Sdavidxu#define LOCK_SAMPLE_WAIT 7 62144518Sdavidxu 63112918Sjeff#if defined(DIAGNOSTIC) 64144518Sdavidxu#define LOCK_INLINE 65144518Sdavidxu#else 66144518Sdavidxu#define LOCK_INLINE __inline 67144518Sdavidxu#endif 68144518Sdavidxu 69144518Sdavidxu#define LK_ALL (LK_HAVE_EXCL | LK_WANT_EXCL | LK_WANT_UPGRADE | \ 70144518Sdavidxu LK_SHARE_NONZERO | LK_WAIT_NONZERO) 71144518Sdavidxu 72112918Sjeff/* 73112918Sjeff * Mutex array variables. Rather than each lockmgr lock having its own mutex, 74112918Sjeff * share a fixed (at boot time) number of mutexes across all lockmgr locks in 75112918Sjeff * order to keep sizeof(struct lock) down. 76144518Sdavidxu */ 77144518Sdavidxustatic struct mtx lock_mtx; 78112918Sjeff 79112918Sjeffstatic int acquire(struct lock **lkpp, int extflags, int wanted); 80112918Sjeffstatic int apause(struct lock *lkp, int flags); 81112918Sjeffstatic int acquiredrain(struct lock *lkp, int extflags) ; 82112918Sjeff 83112918Sjeffstatic void 84144518Sdavidxulockmgr_init(void *dummy __unused) 85112918Sjeff{ 86112918Sjeff mtx_init(&lock_mtx, "lockmgr", NULL, MTX_DEF); 87144518Sdavidxu} 88144518SdavidxuSYSINIT(lmgrinit, SI_SUB_LOCKMGR, SI_ORDER_FIRST, lockmgr_init, NULL) 89144518Sdavidxu 90112918Sjeffstatic LOCK_INLINE void 91144518Sdavidxusharelock(struct lock *lkp, int incr) { 92144518Sdavidxu lkp->lk_flags |= LK_SHARE_NONZERO; 93112918Sjeff lkp->lk_sharecount += incr; 94112918Sjeff} 95112918Sjeff 96144518Sdavidxustatic LOCK_INLINE void 97144518Sdavidxushareunlock(struct lock *lkp, int decr) { 98112918Sjeff 99112918Sjeff KASSERT(lkp->lk_sharecount >= decr, ("shareunlock: count < decr")); 100112918Sjeff 101112918Sjeff if (lkp->lk_sharecount == decr) { 102112918Sjeff lkp->lk_flags &= ~LK_SHARE_NONZERO; 103112918Sjeff if (lkp->lk_flags & (LK_WANT_UPGRADE | LK_WANT_EXCL)) { 104112918Sjeff wakeup(lkp); 105112918Sjeff } 106144518Sdavidxu lkp->lk_sharecount = 0; 107144518Sdavidxu } else { 108157457Sdavidxu lkp->lk_sharecount -= decr; 109112918Sjeff } 110144518Sdavidxu} 111112918Sjeff 112144518Sdavidxu/* 113144518Sdavidxu * This is the waitloop optimization. 114112918Sjeff */ 115144518Sdavidxustatic int 116144518Sdavidxuapause(struct lock *lkp, int flags) 117144518Sdavidxu{ 118144518Sdavidxu#ifdef SMP 119144518Sdavidxu int i, lock_wait; 120144518Sdavidxu#endif 121144518Sdavidxu 122144518Sdavidxu if ((lkp->lk_flags & flags) == 0) 123144518Sdavidxu return 0; 124144518Sdavidxu#ifdef SMP 125144518Sdavidxu for (lock_wait = LOCK_WAIT_TIME; lock_wait > 0; lock_wait--) { 126144518Sdavidxu mtx_unlock(lkp->lk_interlock); 127157457Sdavidxu for (i = LOCK_SAMPLE_WAIT; i > 0; i--) 128144518Sdavidxu if ((lkp->lk_flags & flags) == 0) 129112918Sjeff break; 130144518Sdavidxu mtx_lock(lkp->lk_interlock); 131144518Sdavidxu if ((lkp->lk_flags & flags) == 0) 132144518Sdavidxu return 0; 133112918Sjeff } 134144518Sdavidxu#endif 135144518Sdavidxu return 1; 136144518Sdavidxu} 137144518Sdavidxu 138144518Sdavidxustatic int 139112918Sjeffacquire(struct lock **lkpp, int extflags, int wanted) { 140144518Sdavidxu struct lock *lkp = *lkpp; 141144518Sdavidxu int s, error; 142112918Sjeff 143144518Sdavidxu CTR3(KTR_LOCK, 144157457Sdavidxu "acquire(): lkp == %p, extflags == 0x%x, wanted == 0x%x", 145144518Sdavidxu lkp, extflags, wanted); 146112918Sjeff 147112918Sjeff if ((extflags & LK_NOWAIT) && (lkp->lk_flags & wanted)) { 148112918Sjeff return EBUSY; 149144518Sdavidxu } 150144518Sdavidxu 151144518Sdavidxu if (((lkp->lk_flags | extflags) & LK_NOPAUSE) == 0) { 152144518Sdavidxu error = apause(lkp, wanted); 153144518Sdavidxu if (error == 0) 154144518Sdavidxu return 0; 155144518Sdavidxu } 156112918Sjeff 157112918Sjeff s = splhigh(); 158112918Sjeff while ((lkp->lk_flags & wanted) != 0) { 159112918Sjeff lkp->lk_flags |= LK_WAIT_NONZERO; 160112918Sjeff lkp->lk_waitcount++; 161112918Sjeff error = msleep(lkp, lkp->lk_interlock, lkp->lk_prio, 162112918Sjeff lkp->lk_wmesg, 163112918Sjeff ((extflags & LK_TIMELOCK) ? lkp->lk_timo : 0)); 164112918Sjeff if (lkp->lk_waitcount == 1) { 165112918Sjeff lkp->lk_flags &= ~LK_WAIT_NONZERO; 166112918Sjeff lkp->lk_waitcount = 0; 167112918Sjeff } else { 168112918Sjeff lkp->lk_waitcount--; 169112918Sjeff } 170112918Sjeff if (error) { 171112918Sjeff splx(s); 172112918Sjeff return error; 173112918Sjeff } 174112918Sjeff if (extflags & LK_SLEEPFAIL) { 175144518Sdavidxu splx(s); 176112918Sjeff return ENOLCK; 177112918Sjeff } 178144518Sdavidxu if (lkp->lk_newlock != NULL) { 179144518Sdavidxu mtx_lock(lkp->lk_newlock->lk_interlock); 180144518Sdavidxu mtx_unlock(lkp->lk_interlock); 181112918Sjeff if (lkp->lk_waitcount == 0) 182112918Sjeff wakeup((void *)(&lkp->lk_newlock)); 183144518Sdavidxu *lkpp = lkp = lkp->lk_newlock; 184144518Sdavidxu } 185112918Sjeff } 186112918Sjeff splx(s); 187112918Sjeff return 0; 188144518Sdavidxu} 189144518Sdavidxu 190112918Sjeff/* 191112918Sjeff * Set, change, or release a lock. 192144518Sdavidxu * 193112918Sjeff * Shared requests increment the shared count. Exclusive requests set the 194112918Sjeff * LK_WANT_EXCL flag (preventing further shared locks), and wait for already 195112918Sjeff * accepted shared locks and shared-to-exclusive upgrades to go away. 196112918Sjeff */ 197112918Sjeffint 198112918Sjeff#ifndef DEBUG_LOCKS 199112918Sjefflockmgr(lkp, flags, interlkp, td) 200112918Sjeff#else 201112918Sjeffdebuglockmgr(lkp, flags, interlkp, td, name, file, line) 202112918Sjeff#endif 203112918Sjeff struct lock *lkp; 204112918Sjeff u_int flags; 205112918Sjeff struct mtx *interlkp; 206144518Sdavidxu struct thread *td; 207157457Sdavidxu#ifdef DEBUG_LOCKS 208112918Sjeff const char *name; /* Name of lock function */ 209144518Sdavidxu const char *file; /* Name of file call is from */ 210144518Sdavidxu int line; /* Line number in file */ 211144518Sdavidxu#endif 212112918Sjeff{ 213144518Sdavidxu int error; 214112918Sjeff struct thread *thr; 215144518Sdavidxu int extflags, lockflags; 216144518Sdavidxu 217112918Sjeff CTR5(KTR_LOCK, 218157457Sdavidxu "lockmgr(): lkp == %p (lk_wmesg == \"%s\"), flags == 0x%x, " 219112918Sjeff "interlkp == %p, td == %p", lkp, lkp->lk_wmesg, flags, interlkp, td); 220112918Sjeff 221112918Sjeff error = 0; 222112918Sjeff if (td == NULL) 223112918Sjeff thr = LK_KERNPROC; 224112918Sjeff else 225112918Sjeff thr = td; 226112918Sjeff 227112918Sjeff if ((flags & LK_INTERNAL) == 0) 228112918Sjeff mtx_lock(lkp->lk_interlock); 229157457Sdavidxu if (flags & LK_INTERLOCK) { 230112918Sjeff mtx_assert(interlkp, MA_OWNED | MA_NOTRECURSED); 231 mtx_unlock(interlkp); 232 } 233 234 if ((flags & (LK_NOWAIT|LK_RELEASE)) == 0) 235 WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, 236 &lkp->lk_interlock->mtx_object, 237 "Acquiring lockmgr lock \"%s\"", lkp->lk_wmesg); 238 239 if (panicstr != NULL) { 240 mtx_unlock(lkp->lk_interlock); 241 return (0); 242 } 243 244 extflags = (flags | lkp->lk_flags) & LK_EXTFLG_MASK; 245 246 switch (flags & LK_TYPE_MASK) { 247 248 case LK_SHARED: 249 /* 250 * If we are not the exclusive lock holder, we have to block 251 * while there is an exclusive lock holder or while an 252 * exclusive lock request or upgrade request is in progress. 253 * 254 * However, if TDP_DEADLKTREAT is set, we override exclusive 255 * lock requests or upgrade requests ( but not the exclusive 256 * lock itself ). 257 */ 258 if (lkp->lk_lockholder != thr) { 259 lockflags = LK_HAVE_EXCL; 260 if (td != NULL && !(td->td_pflags & TDP_DEADLKTREAT)) 261 lockflags |= LK_WANT_EXCL | LK_WANT_UPGRADE; 262 error = acquire(&lkp, extflags, lockflags); 263 if (error) 264 break; 265 sharelock(lkp, 1); 266#if defined(DEBUG_LOCKS) 267 lkp->lk_slockholder = thr; 268 lkp->lk_sfilename = file; 269 lkp->lk_slineno = line; 270 lkp->lk_slockername = name; 271#endif 272 break; 273 } 274 /* 275 * We hold an exclusive lock, so downgrade it to shared. 276 * An alternative would be to fail with EDEADLK. 277 */ 278 sharelock(lkp, 1); 279 /* FALLTHROUGH downgrade */ 280 281 case LK_DOWNGRADE: 282 KASSERT(lkp->lk_lockholder == thr && lkp->lk_exclusivecount != 0, 283 ("lockmgr: not holding exclusive lock " 284 "(owner thread (%p) != thread (%p), exlcnt (%d) != 0", 285 lkp->lk_lockholder, thr, lkp->lk_exclusivecount)); 286 sharelock(lkp, lkp->lk_exclusivecount); 287 lkp->lk_exclusivecount = 0; 288 lkp->lk_flags &= ~LK_HAVE_EXCL; 289 lkp->lk_lockholder = LK_NOPROC; 290 if (lkp->lk_waitcount) 291 wakeup((void *)lkp); 292 break; 293 294 case LK_EXCLUPGRADE: 295 /* 296 * If another process is ahead of us to get an upgrade, 297 * then we want to fail rather than have an intervening 298 * exclusive access. 299 */ 300 if (lkp->lk_flags & LK_WANT_UPGRADE) { 301 shareunlock(lkp, 1); 302 error = EBUSY; 303 break; 304 } 305 /* FALLTHROUGH 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 == thr) || (lkp->lk_sharecount <= 0)) 317 panic("lockmgr: upgrade exclusive lock"); 318 shareunlock(lkp, 1); 319 /* 320 * If we are just polling, check to see if we will block. 321 */ 322 if ((extflags & LK_NOWAIT) && 323 ((lkp->lk_flags & LK_WANT_UPGRADE) || 324 lkp->lk_sharecount > 1)) { 325 error = EBUSY; 326 break; 327 } 328 if ((lkp->lk_flags & LK_WANT_UPGRADE) == 0) { 329 /* 330 * We are first shared lock to request an upgrade, so 331 * request upgrade and wait for the shared count to 332 * drop to zero, then take exclusive lock. 333 */ 334 lkp->lk_flags |= LK_WANT_UPGRADE; 335 error = acquire(&lkp, extflags, LK_SHARE_NONZERO); 336 lkp->lk_flags &= ~LK_WANT_UPGRADE; 337 338 if (error) 339 break; 340 lkp->lk_flags |= LK_HAVE_EXCL; 341 lkp->lk_lockholder = thr; 342 if (lkp->lk_exclusivecount != 0) 343 panic("lockmgr: non-zero exclusive count"); 344 lkp->lk_exclusivecount = 1; 345#if defined(DEBUG_LOCKS) 346 lkp->lk_filename = file; 347 lkp->lk_lineno = line; 348 lkp->lk_lockername = name; 349#endif 350 break; 351 } 352 /* 353 * Someone else has requested upgrade. Release our shared 354 * lock, awaken upgrade requestor if we are the last shared 355 * lock, then request an exclusive lock. 356 */ 357 if ( (lkp->lk_flags & (LK_SHARE_NONZERO|LK_WAIT_NONZERO)) == 358 LK_WAIT_NONZERO) 359 wakeup((void *)lkp); 360 /* FALLTHROUGH exclusive request */ 361 362 case LK_EXCLUSIVE: 363 if (lkp->lk_lockholder == thr && thr != LK_KERNPROC) { 364 /* 365 * Recursive lock. 366 */ 367 if ((extflags & (LK_NOWAIT | LK_CANRECURSE)) == 0) 368 panic("lockmgr: locking against myself"); 369 if ((extflags & LK_CANRECURSE) != 0) { 370 lkp->lk_exclusivecount++; 371 break; 372 } 373 } 374 /* 375 * If we are just polling, check to see if we will sleep. 376 */ 377 if ((extflags & LK_NOWAIT) && 378 (lkp->lk_flags & (LK_HAVE_EXCL | LK_WANT_EXCL | LK_WANT_UPGRADE | LK_SHARE_NONZERO))) { 379 error = EBUSY; 380 break; 381 } 382 /* 383 * Try to acquire the want_exclusive flag. 384 */ 385 error = acquire(&lkp, extflags, (LK_HAVE_EXCL | LK_WANT_EXCL)); 386 if (error) 387 break; 388 lkp->lk_flags |= LK_WANT_EXCL; 389 /* 390 * Wait for shared locks and upgrades to finish. 391 */ 392 error = acquire(&lkp, extflags, LK_WANT_UPGRADE | LK_SHARE_NONZERO); 393 lkp->lk_flags &= ~LK_WANT_EXCL; 394 if (error) 395 break; 396 lkp->lk_flags |= LK_HAVE_EXCL; 397 lkp->lk_lockholder = thr; 398 if (lkp->lk_exclusivecount != 0) 399 panic("lockmgr: non-zero exclusive count"); 400 lkp->lk_exclusivecount = 1; 401#if defined(DEBUG_LOCKS) 402 lkp->lk_filename = file; 403 lkp->lk_lineno = line; 404 lkp->lk_lockername = name; 405#endif 406 break; 407 408 case LK_RELEASE: 409 if (lkp->lk_exclusivecount != 0) { 410 if (lkp->lk_lockholder != thr && 411 lkp->lk_lockholder != LK_KERNPROC) { 412 panic("lockmgr: thread %p, not %s %p unlocking", 413 thr, "exclusive lock holder", 414 lkp->lk_lockholder); 415 } 416 if (lkp->lk_exclusivecount == 1) { 417 lkp->lk_flags &= ~LK_HAVE_EXCL; 418 lkp->lk_lockholder = LK_NOPROC; 419 lkp->lk_exclusivecount = 0; 420 } else { 421 lkp->lk_exclusivecount--; 422 } 423 } else if (lkp->lk_flags & LK_SHARE_NONZERO) 424 shareunlock(lkp, 1); 425 if (lkp->lk_flags & LK_WAIT_NONZERO) 426 wakeup((void *)lkp); 427 break; 428 429 case LK_DRAIN: 430 /* 431 * Check that we do not already hold the lock, as it can 432 * never drain if we do. Unfortunately, we have no way to 433 * check for holding a shared lock, but at least we can 434 * check for an exclusive one. 435 */ 436 if (lkp->lk_lockholder == thr) 437 panic("lockmgr: draining against myself"); 438 439 error = acquiredrain(lkp, extflags); 440 if (error) 441 break; 442 lkp->lk_flags |= LK_DRAINING | LK_HAVE_EXCL; 443 lkp->lk_lockholder = thr; 444 lkp->lk_exclusivecount = 1; 445#if defined(DEBUG_LOCKS) 446 lkp->lk_filename = file; 447 lkp->lk_lineno = line; 448 lkp->lk_lockername = name; 449#endif 450 break; 451 452 default: 453 mtx_unlock(lkp->lk_interlock); 454 panic("lockmgr: unknown locktype request %d", 455 flags & LK_TYPE_MASK); 456 /* NOTREACHED */ 457 } 458 if ((lkp->lk_flags & LK_WAITDRAIN) && 459 (lkp->lk_flags & (LK_HAVE_EXCL | LK_WANT_EXCL | LK_WANT_UPGRADE | 460 LK_SHARE_NONZERO | LK_WAIT_NONZERO)) == 0) { 461 lkp->lk_flags &= ~LK_WAITDRAIN; 462 wakeup((void *)&lkp->lk_flags); 463 } 464 mtx_unlock(lkp->lk_interlock); 465 return (error); 466} 467 468static int 469acquiredrain(struct lock *lkp, int extflags) { 470 int error; 471 472 if ((extflags & LK_NOWAIT) && (lkp->lk_flags & LK_ALL)) { 473 return EBUSY; 474 } 475 476 error = apause(lkp, LK_ALL); 477 if (error == 0) 478 return 0; 479 480 while (lkp->lk_flags & LK_ALL) { 481 lkp->lk_flags |= LK_WAITDRAIN; 482 error = msleep(&lkp->lk_flags, lkp->lk_interlock, lkp->lk_prio, 483 lkp->lk_wmesg, 484 ((extflags & LK_TIMELOCK) ? lkp->lk_timo : 0)); 485 if (error) 486 return error; 487 if (extflags & LK_SLEEPFAIL) { 488 return ENOLCK; 489 } 490 } 491 return 0; 492} 493 494/* 495 * Transfer any waiting processes from one lock to another. 496 */ 497void 498transferlockers(from, to) 499 struct lock *from; 500 struct lock *to; 501{ 502 503 KASSERT(from != to, ("lock transfer to self")); 504 KASSERT((from->lk_flags&LK_WAITDRAIN) == 0, ("transfer draining lock")); 505 if (from->lk_waitcount == 0) 506 return; 507 from->lk_newlock = to; 508 wakeup((void *)from); 509 msleep(&from->lk_newlock, NULL, from->lk_prio, "lkxfer", 0); 510 from->lk_newlock = NULL; 511 from->lk_flags &= ~(LK_WANT_EXCL | LK_WANT_UPGRADE); 512 KASSERT(from->lk_waitcount == 0, ("active lock")); 513} 514 515 516/* 517 * Initialize a lock; required before use. 518 */ 519void 520lockinit(lkp, prio, wmesg, timo, flags) 521 struct lock *lkp; 522 int prio; 523 const char *wmesg; 524 int timo; 525 int flags; 526{ 527 CTR5(KTR_LOCK, "lockinit(): lkp == %p, prio == %d, wmesg == \"%s\", " 528 "timo == %d, flags = 0x%x\n", lkp, prio, wmesg, timo, flags); 529 530 lkp->lk_interlock = mtx_pool_alloc(mtxpool_lockbuilder); 531 lkp->lk_flags = (flags & LK_EXTFLG_MASK); 532 lkp->lk_sharecount = 0; 533 lkp->lk_waitcount = 0; 534 lkp->lk_exclusivecount = 0; 535 lkp->lk_prio = prio; 536 lkp->lk_wmesg = wmesg; 537 lkp->lk_timo = timo; 538 lkp->lk_lockholder = LK_NOPROC; 539 lkp->lk_newlock = NULL; 540#ifdef DEBUG_LOCKS 541 lkp->lk_filename = "none"; 542 lkp->lk_lockername = "never exclusive locked"; 543 lkp->lk_lineno = 0; 544 lkp->lk_slockholder = LK_NOPROC; 545 lkp->lk_sfilename = "none"; 546 lkp->lk_slockername = "never share locked"; 547 lkp->lk_slineno = 0; 548#endif 549} 550 551/* 552 * Destroy a lock. 553 */ 554void 555lockdestroy(lkp) 556 struct lock *lkp; 557{ 558 CTR2(KTR_LOCK, "lockdestroy(): lkp == %p (lk_wmesg == \"%s\")", 559 lkp, lkp->lk_wmesg); 560} 561 562/* 563 * Determine the status of a lock. 564 */ 565int 566lockstatus(lkp, td) 567 struct lock *lkp; 568 struct thread *td; 569{ 570 int lock_type = 0; 571 572 mtx_lock(lkp->lk_interlock); 573 if (lkp->lk_exclusivecount != 0) { 574 if (td == NULL || lkp->lk_lockholder == td) 575 lock_type = LK_EXCLUSIVE; 576 else 577 lock_type = LK_EXCLOTHER; 578 } else if (lkp->lk_sharecount != 0) 579 lock_type = LK_SHARED; 580 mtx_unlock(lkp->lk_interlock); 581 return (lock_type); 582} 583 584/* 585 * Determine the number of holders of a lock. 586 */ 587int 588lockcount(lkp) 589 struct lock *lkp; 590{ 591 int count; 592 593 mtx_lock(lkp->lk_interlock); 594 count = lkp->lk_exclusivecount + lkp->lk_sharecount; 595 mtx_unlock(lkp->lk_interlock); 596 return (count); 597} 598 599/* 600 * Print out information about state of a lock. Used by VOP_PRINT 601 * routines to display status about contained locks. 602 */ 603void 604lockmgr_printinfo(lkp) 605 struct lock *lkp; 606{ 607 608 if (lkp->lk_sharecount) 609 printf(" lock type %s: SHARED (count %d)", lkp->lk_wmesg, 610 lkp->lk_sharecount); 611 else if (lkp->lk_flags & LK_HAVE_EXCL) 612 printf(" lock type %s: EXCL (count %d) by thread %p (pid %d)", 613 lkp->lk_wmesg, lkp->lk_exclusivecount, 614 lkp->lk_lockholder, lkp->lk_lockholder->td_proc->p_pid); 615 if (lkp->lk_waitcount > 0) 616 printf(" with %d pending", lkp->lk_waitcount); 617} 618