kern_lock.c revision 83420
1219820Sjeff/* 2219820Sjeff * Copyright (c) 1995 3219820Sjeff * The Regents of the University of California. All rights reserved. 4219820Sjeff * 5219820Sjeff * Copyright (C) 1997 6219820Sjeff * John S. Dyson. All rights reserved. 7219820Sjeff * 8219820Sjeff * This code contains ideas from software contributed to Berkeley by 9219820Sjeff * Avadis Tevanian, Jr., Michael Wayne Young, and the Mach Operating 10219820Sjeff * System project at Carnegie-Mellon University. 11219820Sjeff * 12219820Sjeff * Redistribution and use in source and binary forms, with or without 13219820Sjeff * modification, are permitted provided that the following conditions 14219820Sjeff * are met: 15219820Sjeff * 1. Redistributions of source code must retain the above copyright 16219820Sjeff * notice, this list of conditions and the following disclaimer. 17219820Sjeff * 2. Redistributions in binary form must reproduce the above copyright 18219820Sjeff * notice, this list of conditions and the following disclaimer in the 19219820Sjeff * documentation and/or other materials provided with the distribution. 20219820Sjeff * 3. All advertising materials mentioning features or use of this software 21219820Sjeff * must display the following acknowledgement: 22219820Sjeff * This product includes software developed by the University of 23219820Sjeff * California, Berkeley and its contributors. 24219820Sjeff * 4. Neither the name of the University nor the names of its contributors 25219820Sjeff * may be used to endorse or promote products derived from this software 26219820Sjeff * without specific prior written permission. 27219820Sjeff * 28219820Sjeff * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 29219820Sjeff * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 30219820Sjeff * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 31219820Sjeff * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 32219820Sjeff * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 33219820Sjeff * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 34219820Sjeff * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 35219820Sjeff * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 36219820Sjeff * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 37219820Sjeff * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 38219820Sjeff * SUCH DAMAGE. 39272407Shselasky * 40219820Sjeff * @(#)kern_lock.c 8.18 (Berkeley) 5/21/95 41277160Shselasky * $FreeBSD: head/sys/kern/kern_lock.c 83420 2001-09-13 22:33:37Z jhb $ 42277160Shselasky */ 43277160Shselasky 44277160Shselasky#include <sys/param.h> 45277160Shselasky#include <sys/proc.h> 46277160Shselasky#include <sys/kernel.h> 47277160Shselasky#include <sys/lock.h> 48219820Sjeff#include <sys/malloc.h> 49219820Sjeff#include <sys/mutex.h> 50275228Shselasky#include <sys/systm.h> 51219820Sjeff 52219820Sjeff/* 53219820Sjeff * Locking primitives implementation. 54275228Shselasky * Locks provide shared/exclusive sychronization. 55219820Sjeff */ 56219820Sjeff 57219820Sjeff#define LOCK_WAIT_TIME 100 58219820Sjeff#define LOCK_SAMPLE_WAIT 7 59219820Sjeff 60219820Sjeff#if defined(DIAGNOSTIC) 61219820Sjeff#define LOCK_INLINE 62219820Sjeff#else 63219820Sjeff#define LOCK_INLINE __inline 64219820Sjeff#endif 65219820Sjeff 66219820Sjeff#define LK_ALL (LK_HAVE_EXCL | LK_WANT_EXCL | LK_WANT_UPGRADE | \ 67219820Sjeff LK_SHARE_NONZERO | LK_WAIT_NONZERO) 68219820Sjeff 69219820Sjeff/* 70219820Sjeff * Mutex array variables. Rather than each lockmgr lock having its own mutex, 71219820Sjeff * share a fixed (at boot time) number of mutexes across all lockmgr locks in 72219820Sjeff * order to keep sizeof(struct lock) down. 73219820Sjeff */ 74219820Sjeffextern int lock_nmtx; 75219820Sjeffint lock_mtx_selector; 76219820Sjeffstruct mtx *lock_mtx_array; 77219820Sjeffstatic struct mtx lock_mtx; 78219820Sjeff 79219820Sjeffstatic int acquire(struct lock *lkp, int extflags, int wanted); 80219820Sjeffstatic int apause(struct lock *lkp, int flags); 81219820Sjeffstatic int acquiredrain(struct lock *lkp, int extflags) ; 82219820Sjeff 83219820Sjeffstatic void 84219820Sjefflockmgr_init(void *dummy __unused) 85219820Sjeff{ 86219820Sjeff int i; 87219820Sjeff 88219820Sjeff /* 89219820Sjeff * Initialize the lockmgr protection mutex if it hasn't already been 90219820Sjeff * done. Unless something changes about kernel startup order, VM 91219820Sjeff * initialization will always cause this mutex to already be 92219820Sjeff * initialized in a call to lockinit(). 93219820Sjeff */ 94219820Sjeff if (lock_mtx_selector == 0) 95219820Sjeff mtx_init(&lock_mtx, "lockmgr", MTX_DEF); 96219820Sjeff else { 97219820Sjeff /* 98219820Sjeff * This is necessary if (lock_nmtx == 1) and doesn't hurt 99219820Sjeff * otherwise. 100219820Sjeff */ 101219820Sjeff lock_mtx_selector = 0; 102219820Sjeff } 103219820Sjeff 104219820Sjeff lock_mtx_array = (struct mtx *)malloc(sizeof(struct mtx) * lock_nmtx, 105219820Sjeff M_CACHE, M_WAITOK); 106219820Sjeff for (i = 0; i < lock_nmtx; i++) 107219820Sjeff mtx_init(&lock_mtx_array[i], "lockmgr interlock", MTX_DEF); 108219820Sjeff} 109219820SjeffSYSINIT(lmgrinit, SI_SUB_LOCK, SI_ORDER_FIRST, lockmgr_init, NULL) 110219820Sjeff 111219820Sjeffstatic LOCK_INLINE void 112219820Sjeffsharelock(struct lock *lkp, int incr) { 113219820Sjeff lkp->lk_flags |= LK_SHARE_NONZERO; 114219820Sjeff lkp->lk_sharecount += incr; 115219820Sjeff} 116219820Sjeff 117219820Sjeffstatic LOCK_INLINE void 118219820Sjeffshareunlock(struct lock *lkp, int decr) { 119 120 KASSERT(lkp->lk_sharecount >= decr, ("shareunlock: count < decr")); 121 122 if (lkp->lk_sharecount == decr) { 123 lkp->lk_flags &= ~LK_SHARE_NONZERO; 124 if (lkp->lk_flags & (LK_WANT_UPGRADE | LK_WANT_EXCL)) { 125 wakeup(lkp); 126 } 127 lkp->lk_sharecount = 0; 128 } else { 129 lkp->lk_sharecount -= decr; 130 } 131} 132 133/* 134 * This is the waitloop optimization. 135 */ 136static int 137apause(struct lock *lkp, int flags) 138{ 139#ifdef SMP 140 int i, lock_wait; 141#endif 142 143 if ((lkp->lk_flags & flags) == 0) 144 return 0; 145#ifdef SMP 146 for (lock_wait = LOCK_WAIT_TIME; lock_wait > 0; lock_wait--) { 147 mtx_unlock(lkp->lk_interlock); 148 for (i = LOCK_SAMPLE_WAIT; i > 0; i--) 149 if ((lkp->lk_flags & flags) == 0) 150 break; 151 mtx_lock(lkp->lk_interlock); 152 if ((lkp->lk_flags & flags) == 0) 153 return 0; 154 } 155#endif 156 return 1; 157} 158 159static int 160acquire(struct lock *lkp, int extflags, int wanted) { 161 int s, error; 162 163 CTR3(KTR_LOCKMGR, 164 "acquire(): lkp == %p, extflags == 0x%x, wanted == 0x%x\n", 165 lkp, extflags, wanted); 166 167 if ((extflags & LK_NOWAIT) && (lkp->lk_flags & wanted)) { 168 return EBUSY; 169 } 170 171 if (((lkp->lk_flags | extflags) & LK_NOPAUSE) == 0) { 172 error = apause(lkp, wanted); 173 if (error == 0) 174 return 0; 175 } 176 177 s = splhigh(); 178 while ((lkp->lk_flags & wanted) != 0) { 179 lkp->lk_flags |= LK_WAIT_NONZERO; 180 lkp->lk_waitcount++; 181 error = msleep(lkp, lkp->lk_interlock, lkp->lk_prio, 182 lkp->lk_wmesg, lkp->lk_timo); 183 if (lkp->lk_waitcount == 1) { 184 lkp->lk_flags &= ~LK_WAIT_NONZERO; 185 lkp->lk_waitcount = 0; 186 } else { 187 lkp->lk_waitcount--; 188 } 189 if (error) { 190 splx(s); 191 return error; 192 } 193 if (extflags & LK_SLEEPFAIL) { 194 splx(s); 195 return ENOLCK; 196 } 197 } 198 splx(s); 199 return 0; 200} 201 202/* 203 * Set, change, or release a lock. 204 * 205 * Shared requests increment the shared count. Exclusive requests set the 206 * LK_WANT_EXCL flag (preventing further shared locks), and wait for already 207 * accepted shared locks and shared-to-exclusive upgrades to go away. 208 */ 209int 210#ifndef DEBUG_LOCKS 211lockmgr(lkp, flags, interlkp, td) 212#else 213debuglockmgr(lkp, flags, interlkp, td, name, file, line) 214#endif 215 struct lock *lkp; 216 u_int flags; 217 struct mtx *interlkp; 218 struct thread *td; 219#ifdef DEBUG_LOCKS 220 const char *name; /* Name of lock function */ 221 const char *file; /* Name of file call is from */ 222 int line; /* Line number in file */ 223#endif 224{ 225 int error; 226 pid_t pid; 227 int extflags, lockflags; 228 229 CTR5(KTR_LOCKMGR, 230 "lockmgr(): lkp == %p (lk_wmesg == \"%s\"), flags == 0x%x, " 231 "interlkp == %p, td == %p", lkp, lkp->lk_wmesg, flags, interlkp, td); 232 233 error = 0; 234 if (td == NULL) 235 pid = LK_KERNPROC; 236 else 237 pid = td->td_proc->p_pid; 238 239 mtx_lock(lkp->lk_interlock); 240 if (flags & LK_INTERLOCK) { 241 mtx_assert(interlkp, MA_OWNED | MA_NOTRECURSED); 242 mtx_unlock(interlkp); 243 } 244 245 if (panicstr != NULL) { 246 mtx_unlock(lkp->lk_interlock); 247 return (0); 248 } 249 250 extflags = (flags | lkp->lk_flags) & LK_EXTFLG_MASK; 251 252 switch (flags & LK_TYPE_MASK) { 253 254 case LK_SHARED: 255 /* 256 * If we are not the exclusive lock holder, we have to block 257 * while there is an exclusive lock holder or while an 258 * exclusive lock request or upgrade request is in progress. 259 * 260 * However, if TDF_DEADLKTREAT is set, we override exclusive 261 * lock requests or upgrade requests ( but not the exclusive 262 * lock itself ). 263 */ 264 if (lkp->lk_lockholder != pid) { 265 lockflags = LK_HAVE_EXCL; 266 mtx_lock_spin(&sched_lock); 267 if (td != NULL && !(td->td_flags & TDF_DEADLKTREAT)) 268 lockflags |= LK_WANT_EXCL | LK_WANT_UPGRADE; 269 mtx_unlock_spin(&sched_lock); 270 error = acquire(lkp, extflags, lockflags); 271 if (error) 272 break; 273 sharelock(lkp, 1); 274 break; 275 } 276 /* 277 * We hold an exclusive lock, so downgrade it to shared. 278 * An alternative would be to fail with EDEADLK. 279 */ 280 sharelock(lkp, 1); 281 /* fall into downgrade */ 282 283 case LK_DOWNGRADE: 284 KASSERT(lkp->lk_lockholder == pid && lkp->lk_exclusivecount != 0, 285 ("lockmgr: not holding exclusive lock " 286 "(owner pid (%d) != pid (%d), exlcnt (%d) != 0", 287 lkp->lk_lockholder, pid, lkp->lk_exclusivecount)); 288 sharelock(lkp, lkp->lk_exclusivecount); 289 lkp->lk_exclusivecount = 0; 290 lkp->lk_flags &= ~LK_HAVE_EXCL; 291 lkp->lk_lockholder = LK_NOPROC; 292 if (lkp->lk_waitcount) 293 wakeup((void *)lkp); 294 break; 295 296 case LK_EXCLUPGRADE: 297 /* 298 * If another process is ahead of us to get an upgrade, 299 * then we want to fail rather than have an intervening 300 * exclusive access. 301 */ 302 if (lkp->lk_flags & LK_WANT_UPGRADE) { 303 shareunlock(lkp, 1); 304 error = EBUSY; 305 break; 306 } 307 /* fall into normal upgrade */ 308 309 case LK_UPGRADE: 310 /* 311 * Upgrade a shared lock to an exclusive one. If another 312 * shared lock has already requested an upgrade to an 313 * exclusive lock, our shared lock is released and an 314 * exclusive lock is requested (which will be granted 315 * after the upgrade). If we return an error, the file 316 * will always be unlocked. 317 */ 318 if ((lkp->lk_lockholder == pid) || (lkp->lk_sharecount <= 0)) 319 panic("lockmgr: upgrade exclusive lock"); 320 shareunlock(lkp, 1); 321 /* 322 * If we are just polling, check to see if we will block. 323 */ 324 if ((extflags & LK_NOWAIT) && 325 ((lkp->lk_flags & LK_WANT_UPGRADE) || 326 lkp->lk_sharecount > 1)) { 327 error = EBUSY; 328 break; 329 } 330 if ((lkp->lk_flags & LK_WANT_UPGRADE) == 0) { 331 /* 332 * We are first shared lock to request an upgrade, so 333 * request upgrade and wait for the shared count to 334 * drop to zero, then take exclusive lock. 335 */ 336 lkp->lk_flags |= LK_WANT_UPGRADE; 337 error = acquire(lkp, extflags, LK_SHARE_NONZERO); 338 lkp->lk_flags &= ~LK_WANT_UPGRADE; 339 340 if (error) 341 break; 342 lkp->lk_flags |= LK_HAVE_EXCL; 343 lkp->lk_lockholder = pid; 344 if (lkp->lk_exclusivecount != 0) 345 panic("lockmgr: non-zero exclusive count"); 346 lkp->lk_exclusivecount = 1; 347#if defined(DEBUG_LOCKS) 348 lkp->lk_filename = file; 349 lkp->lk_lineno = line; 350 lkp->lk_lockername = name; 351#endif 352 break; 353 } 354 /* 355 * Someone else has requested upgrade. Release our shared 356 * lock, awaken upgrade requestor if we are the last shared 357 * lock, then request an exclusive lock. 358 */ 359 if ( (lkp->lk_flags & (LK_SHARE_NONZERO|LK_WAIT_NONZERO)) == 360 LK_WAIT_NONZERO) 361 wakeup((void *)lkp); 362 /* fall into exclusive request */ 363 364 case LK_EXCLUSIVE: 365 if (lkp->lk_lockholder == pid && pid != LK_KERNPROC) { 366 /* 367 * Recursive lock. 368 */ 369 if ((extflags & (LK_NOWAIT | LK_CANRECURSE)) == 0) 370 panic("lockmgr: locking against myself"); 371 if ((extflags & LK_CANRECURSE) != 0) { 372 lkp->lk_exclusivecount++; 373 break; 374 } 375 } 376 /* 377 * If we are just polling, check to see if we will sleep. 378 */ 379 if ((extflags & LK_NOWAIT) && 380 (lkp->lk_flags & (LK_HAVE_EXCL | LK_WANT_EXCL | LK_WANT_UPGRADE | LK_SHARE_NONZERO))) { 381 error = EBUSY; 382 break; 383 } 384 /* 385 * Try to acquire the want_exclusive flag. 386 */ 387 error = acquire(lkp, extflags, (LK_HAVE_EXCL | LK_WANT_EXCL)); 388 if (error) 389 break; 390 lkp->lk_flags |= LK_WANT_EXCL; 391 /* 392 * Wait for shared locks and upgrades to finish. 393 */ 394 error = acquire(lkp, extflags, LK_WANT_UPGRADE | LK_SHARE_NONZERO); 395 lkp->lk_flags &= ~LK_WANT_EXCL; 396 if (error) 397 break; 398 lkp->lk_flags |= LK_HAVE_EXCL; 399 lkp->lk_lockholder = pid; 400 if (lkp->lk_exclusivecount != 0) 401 panic("lockmgr: non-zero exclusive count"); 402 lkp->lk_exclusivecount = 1; 403#if defined(DEBUG_LOCKS) 404 lkp->lk_filename = file; 405 lkp->lk_lineno = line; 406 lkp->lk_lockername = name; 407#endif 408 break; 409 410 case LK_RELEASE: 411 if (lkp->lk_exclusivecount != 0) { 412 if (lkp->lk_lockholder != pid && 413 lkp->lk_lockholder != LK_KERNPROC) { 414 panic("lockmgr: pid %d, not %s %d unlocking", 415 pid, "exclusive lock holder", 416 lkp->lk_lockholder); 417 } 418 if (lkp->lk_exclusivecount == 1) { 419 lkp->lk_flags &= ~LK_HAVE_EXCL; 420 lkp->lk_lockholder = LK_NOPROC; 421 lkp->lk_exclusivecount = 0; 422 } else { 423 lkp->lk_exclusivecount--; 424 } 425 } else if (lkp->lk_flags & LK_SHARE_NONZERO) 426 shareunlock(lkp, 1); 427 if (lkp->lk_flags & LK_WAIT_NONZERO) 428 wakeup((void *)lkp); 429 break; 430 431 case LK_DRAIN: 432 /* 433 * Check that we do not already hold the lock, as it can 434 * never drain if we do. Unfortunately, we have no way to 435 * check for holding a shared lock, but at least we can 436 * check for an exclusive one. 437 */ 438 if (lkp->lk_lockholder == pid) 439 panic("lockmgr: draining against myself"); 440 441 error = acquiredrain(lkp, extflags); 442 if (error) 443 break; 444 lkp->lk_flags |= LK_DRAINING | LK_HAVE_EXCL; 445 lkp->lk_lockholder = pid; 446 lkp->lk_exclusivecount = 1; 447#if defined(DEBUG_LOCKS) 448 lkp->lk_filename = file; 449 lkp->lk_lineno = line; 450 lkp->lk_lockername = name; 451#endif 452 break; 453 454 default: 455 mtx_unlock(lkp->lk_interlock); 456 panic("lockmgr: unknown locktype request %d", 457 flags & LK_TYPE_MASK); 458 /* NOTREACHED */ 459 } 460 if ((lkp->lk_flags & LK_WAITDRAIN) && 461 (lkp->lk_flags & (LK_HAVE_EXCL | LK_WANT_EXCL | LK_WANT_UPGRADE | 462 LK_SHARE_NONZERO | LK_WAIT_NONZERO)) == 0) { 463 lkp->lk_flags &= ~LK_WAITDRAIN; 464 wakeup((void *)&lkp->lk_flags); 465 } 466 mtx_unlock(lkp->lk_interlock); 467 return (error); 468} 469 470static int 471acquiredrain(struct lock *lkp, int extflags) { 472 int error; 473 474 if ((extflags & LK_NOWAIT) && (lkp->lk_flags & LK_ALL)) { 475 return EBUSY; 476 } 477 478 error = apause(lkp, LK_ALL); 479 if (error == 0) 480 return 0; 481 482 while (lkp->lk_flags & LK_ALL) { 483 lkp->lk_flags |= LK_WAITDRAIN; 484 error = msleep(&lkp->lk_flags, lkp->lk_interlock, lkp->lk_prio, 485 lkp->lk_wmesg, lkp->lk_timo); 486 if (error) 487 return error; 488 if (extflags & LK_SLEEPFAIL) { 489 return ENOLCK; 490 } 491 } 492 return 0; 493} 494 495/* 496 * Initialize a lock; required before use. 497 */ 498void 499lockinit(lkp, prio, wmesg, timo, flags) 500 struct lock *lkp; 501 int prio; 502 char *wmesg; 503 int timo; 504 int flags; 505{ 506 CTR5(KTR_LOCKMGR, "lockinit(): lkp == %p, prio == %d, wmesg == \"%s\", " 507 "timo == %d, flags = 0x%x\n", lkp, prio, wmesg, timo, flags); 508 509 if (lock_mtx_array != NULL) { 510 mtx_lock(&lock_mtx); 511 lkp->lk_interlock = &lock_mtx_array[lock_mtx_selector]; 512 lock_mtx_selector++; 513 if (lock_mtx_selector == lock_nmtx) 514 lock_mtx_selector = 0; 515 mtx_unlock(&lock_mtx); 516 } else { 517 /* 518 * Giving lockmgr locks that are initialized during boot a 519 * pointer to the internal lockmgr mutex is safe, since the 520 * lockmgr code itself doesn't call lockinit() (which could 521 * cause mutex recursion). 522 */ 523 if (lock_mtx_selector == 0) { 524 /* 525 * This case only happens during kernel bootstrapping, 526 * so there's no reason to protect modification of 527 * lock_mtx_selector or lock_mtx. 528 */ 529 mtx_init(&lock_mtx, "lockmgr", MTX_DEF); 530 lock_mtx_selector = 1; 531 } 532 lkp->lk_interlock = &lock_mtx; 533 } 534 lkp->lk_flags = (flags & LK_EXTFLG_MASK); 535 lkp->lk_sharecount = 0; 536 lkp->lk_waitcount = 0; 537 lkp->lk_exclusivecount = 0; 538 lkp->lk_prio = prio; 539 lkp->lk_wmesg = wmesg; 540 lkp->lk_timo = timo; 541 lkp->lk_lockholder = LK_NOPROC; 542} 543 544/* 545 * Destroy a lock. 546 */ 547void 548lockdestroy(lkp) 549 struct lock *lkp; 550{ 551 CTR2(KTR_LOCKMGR, "lockdestroy(): lkp == %p (lk_wmesg == \"%s\")", 552 lkp, lkp->lk_wmesg); 553} 554 555/* 556 * Determine the status of a lock. 557 */ 558int 559lockstatus(lkp, td) 560 struct lock *lkp; 561 struct thread *td; 562{ 563 int lock_type = 0; 564 565 mtx_lock(lkp->lk_interlock); 566 if (lkp->lk_exclusivecount != 0) { 567 if (td == NULL || lkp->lk_lockholder == td->td_proc->p_pid) 568 lock_type = LK_EXCLUSIVE; 569 else 570 lock_type = LK_EXCLOTHER; 571 } else if (lkp->lk_sharecount != 0) 572 lock_type = LK_SHARED; 573 mtx_unlock(lkp->lk_interlock); 574 return (lock_type); 575} 576 577/* 578 * Determine the number of holders of a lock. 579 */ 580int 581lockcount(lkp) 582 struct lock *lkp; 583{ 584 int count; 585 586 mtx_lock(lkp->lk_interlock); 587 count = lkp->lk_exclusivecount + lkp->lk_sharecount; 588 mtx_unlock(lkp->lk_interlock); 589 return (count); 590} 591 592/* 593 * Print out information about state of a lock. Used by VOP_PRINT 594 * routines to display status about contained locks. 595 */ 596void 597lockmgr_printinfo(lkp) 598 struct lock *lkp; 599{ 600 601 if (lkp->lk_sharecount) 602 printf(" lock type %s: SHARED (count %d)", lkp->lk_wmesg, 603 lkp->lk_sharecount); 604 else if (lkp->lk_flags & LK_HAVE_EXCL) 605 printf(" lock type %s: EXCL (count %d) by pid %d", 606 lkp->lk_wmesg, lkp->lk_exclusivecount, lkp->lk_lockholder); 607 if (lkp->lk_waitcount > 0) 608 printf(" with %d pending", lkp->lk_waitcount); 609} 610