kern_lock.c revision 175635
1139804Simp/*- 224269Speter * Copyright (c) 1995 324269Speter * The Regents of the University of California. All rights reserved. 424269Speter * 528345Sdyson * Copyright (C) 1997 628345Sdyson * John S. Dyson. All rights reserved. 728345Sdyson * 824269Speter * This code contains ideas from software contributed to Berkeley by 924269Speter * Avadis Tevanian, Jr., Michael Wayne Young, and the Mach Operating 1024269Speter * System project at Carnegie-Mellon University. 1124269Speter * 1224269Speter * Redistribution and use in source and binary forms, with or without 1324269Speter * modification, are permitted provided that the following conditions 1424269Speter * are met: 1524269Speter * 1. Redistributions of source code must retain the above copyright 1624269Speter * notice, this list of conditions and the following disclaimer. 1724269Speter * 2. Redistributions in binary form must reproduce the above copyright 1824269Speter * notice, this list of conditions and the following disclaimer in the 1924269Speter * documentation and/or other materials provided with the distribution. 2024269Speter * 3. All advertising materials mentioning features or use of this software 2124269Speter * must display the following acknowledgement: 2224269Speter * This product includes software developed by the University of 2324269Speter * California, Berkeley and its contributors. 2424269Speter * 4. Neither the name of the University nor the names of its contributors 2524269Speter * may be used to endorse or promote products derived from this software 2624269Speter * without specific prior written permission. 2724269Speter * 2824269Speter * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 2924269Speter * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 3024269Speter * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 3124269Speter * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 3224269Speter * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 3324269Speter * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 3424269Speter * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 3524269Speter * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 3624269Speter * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 3724269Speter * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 3824269Speter * SUCH DAMAGE. 3924269Speter * 4024269Speter * @(#)kern_lock.c 8.18 (Berkeley) 5/21/95 4124269Speter */ 4224269Speter 43116182Sobrien#include <sys/cdefs.h> 44116182Sobrien__FBSDID("$FreeBSD: head/sys/kern/kern_lock.c 175635 2008-01-24 12:34:30Z attilio $"); 45116182Sobrien 46161322Sjhb#include "opt_ddb.h" 47164159Skmacy#include "opt_global.h" 48161322Sjhb 4924269Speter#include <sys/param.h> 50150807Srwatson#include <sys/kdb.h> 5167046Sjasone#include <sys/kernel.h> 5284812Sjhb#include <sys/ktr.h> 5324269Speter#include <sys/lock.h> 54102477Sbde#include <sys/lockmgr.h> 5567353Sjhb#include <sys/mutex.h> 56102477Sbde#include <sys/proc.h> 5724273Speter#include <sys/systm.h> 58164159Skmacy#include <sys/lock_profile.h> 59148668Sjeff#ifdef DEBUG_LOCKS 60148668Sjeff#include <sys/stack.h> 61148668Sjeff#endif 6224269Speter 63173733Sattiliostatic void assert_lockmgr(struct lock_object *lock, int what); 64161322Sjhb#ifdef DDB 65161322Sjhb#include <ddb/ddb.h> 66164246Skmacystatic void db_show_lockmgr(struct lock_object *lock); 67161322Sjhb#endif 68167368Sjhbstatic void lock_lockmgr(struct lock_object *lock, int how); 69167368Sjhbstatic int unlock_lockmgr(struct lock_object *lock); 70161322Sjhb 71164246Skmacystruct lock_class lock_class_lockmgr = { 72167366Sjhb .lc_name = "lockmgr", 73167366Sjhb .lc_flags = LC_SLEEPLOCK | LC_SLEEPABLE | LC_RECURSABLE | LC_UPGRADABLE, 74173733Sattilio .lc_assert = assert_lockmgr, 75164246Skmacy#ifdef DDB 76167368Sjhb .lc_ddb_show = db_show_lockmgr, 77164246Skmacy#endif 78167368Sjhb .lc_lock = lock_lockmgr, 79167368Sjhb .lc_unlock = unlock_lockmgr, 80164246Skmacy}; 81164246Skmacy 8224269Speter/* 8324269Speter * Locking primitives implementation. 8424269Speter * Locks provide shared/exclusive sychronization. 8524269Speter */ 8624269Speter 87167368Sjhbvoid 88173733Sattilioassert_lockmgr(struct lock_object *lock, int what) 89173733Sattilio{ 90173733Sattilio 91173733Sattilio panic("lockmgr locks do not support assertions"); 92173733Sattilio} 93173733Sattilio 94173733Sattiliovoid 95167368Sjhblock_lockmgr(struct lock_object *lock, int how) 96167368Sjhb{ 97167368Sjhb 98167368Sjhb panic("lockmgr locks do not support sleep interlocking"); 99167368Sjhb} 100167368Sjhb 101167368Sjhbint 102167368Sjhbunlock_lockmgr(struct lock_object *lock) 103167368Sjhb{ 104167368Sjhb 105167368Sjhb panic("lockmgr locks do not support sleep interlocking"); 106167368Sjhb} 107167368Sjhb 108175166Sattilio#define COUNT(td, x) ((td)->td_locks += (x)) 10929653Sdyson#define LK_ALL (LK_HAVE_EXCL | LK_WANT_EXCL | LK_WANT_UPGRADE | \ 11029653Sdyson LK_SHARE_NONZERO | LK_WAIT_NONZERO) 11129653Sdyson 112167012Skmacystatic int acquire(struct lock **lkpp, int extflags, int wanted, int *contested, uint64_t *waittime); 11329653Sdysonstatic int acquiredrain(struct lock *lkp, int extflags) ; 11424269Speter 115144705Sjeffstatic __inline void 116144082Sjeffsharelock(struct thread *td, struct lock *lkp, int incr) { 11728345Sdyson lkp->lk_flags |= LK_SHARE_NONZERO; 11828345Sdyson lkp->lk_sharecount += incr; 119144082Sjeff COUNT(td, incr); 12028345Sdyson} 12124269Speter 122144705Sjeffstatic __inline void 123144082Sjeffshareunlock(struct thread *td, struct lock *lkp, int decr) { 12442453Seivind 12542408Seivind KASSERT(lkp->lk_sharecount >= decr, ("shareunlock: count < decr")); 12624269Speter 127144082Sjeff COUNT(td, -decr); 12834194Sdyson if (lkp->lk_sharecount == decr) { 12928345Sdyson lkp->lk_flags &= ~LK_SHARE_NONZERO; 13034194Sdyson if (lkp->lk_flags & (LK_WANT_UPGRADE | LK_WANT_EXCL)) { 13134194Sdyson wakeup(lkp); 13234194Sdyson } 13334194Sdyson lkp->lk_sharecount = 0; 13434194Sdyson } else { 13534194Sdyson lkp->lk_sharecount -= decr; 13634194Sdyson } 13728345Sdyson} 13828345Sdyson 13928345Sdysonstatic int 140167012Skmacyacquire(struct lock **lkpp, int extflags, int wanted, int *contested, uint64_t *waittime) 141140711Sjeff{ 142107414Smckusick struct lock *lkp = *lkpp; 143144589Sjeff int error; 144112106Sjhb CTR3(KTR_LOCK, 145132587Srwatson "acquire(): lkp == %p, extflags == 0x%x, wanted == 0x%x", 14666615Sjasone lkp, extflags, wanted); 14766615Sjasone 148144589Sjeff if ((extflags & LK_NOWAIT) && (lkp->lk_flags & wanted)) 14928345Sdyson return EBUSY; 150144589Sjeff error = 0; 151167012Skmacy if ((lkp->lk_flags & wanted) != 0) 152167012Skmacy lock_profile_obtain_lock_failed(&lkp->lk_object, contested, waittime); 153167012Skmacy 15428345Sdyson while ((lkp->lk_flags & wanted) != 0) { 155144589Sjeff CTR2(KTR_LOCK, 156144589Sjeff "acquire(): lkp == %p, lk_flags == 0x%x sleeping", 157144589Sjeff lkp, lkp->lk_flags); 15828345Sdyson lkp->lk_flags |= LK_WAIT_NONZERO; 15928345Sdyson lkp->lk_waitcount++; 16069432Sjake error = msleep(lkp, lkp->lk_interlock, lkp->lk_prio, 16188318Sdillon lkp->lk_wmesg, 16288318Sdillon ((extflags & LK_TIMELOCK) ? lkp->lk_timo : 0)); 163144589Sjeff lkp->lk_waitcount--; 164144589Sjeff if (lkp->lk_waitcount == 0) 16528345Sdyson lkp->lk_flags &= ~LK_WAIT_NONZERO; 166144589Sjeff if (error) 167144589Sjeff break; 16828345Sdyson if (extflags & LK_SLEEPFAIL) { 169144589Sjeff error = ENOLCK; 170144589Sjeff break; 17128345Sdyson } 172107414Smckusick if (lkp->lk_newlock != NULL) { 173107414Smckusick mtx_lock(lkp->lk_newlock->lk_interlock); 174107414Smckusick mtx_unlock(lkp->lk_interlock); 175107414Smckusick if (lkp->lk_waitcount == 0) 176107414Smckusick wakeup((void *)(&lkp->lk_newlock)); 177107414Smckusick *lkpp = lkp = lkp->lk_newlock; 178107414Smckusick } 17928345Sdyson } 180144589Sjeff mtx_assert(lkp->lk_interlock, MA_OWNED); 181144589Sjeff return (error); 18228345Sdyson} 18328345Sdyson 18424269Speter/* 18524269Speter * Set, change, or release a lock. 18624269Speter * 18724269Speter * Shared requests increment the shared count. Exclusive requests set the 18824269Speter * LK_WANT_EXCL flag (preventing further shared locks), and wait for already 18924269Speter * accepted shared locks and shared-to-exclusive upgrades to go away. 19024269Speter */ 19124269Speterint 192175635Sattilio_lockmgr(struct lock *lkp, u_int flags, struct mtx *interlkp, char *file, 193175635Sattilio int line) 194164159Skmacy 19524269Speter{ 196175635Sattilio struct thread *td; 19724269Speter int error; 19872227Sjhb int extflags, lockflags; 199167012Skmacy int contested = 0; 200167012Skmacy uint64_t waitstart = 0; 201174948Sattilio 20224269Speter error = 0; 203175635Sattilio td = curthread; 20428345Sdyson 205111463Sjeff if ((flags & LK_INTERNAL) == 0) 206111463Sjeff mtx_lock(lkp->lk_interlock); 207140711Sjeff CTR6(KTR_LOCK, 208140711Sjeff "lockmgr(): lkp == %p (lk_wmesg == \"%s\"), owner == %p, exclusivecount == %d, flags == 0x%x, " 209140711Sjeff "td == %p", lkp, lkp->lk_wmesg, lkp->lk_lockholder, 210140711Sjeff lkp->lk_exclusivecount, flags, td); 211148668Sjeff#ifdef DEBUG_LOCKS 212148668Sjeff { 213148668Sjeff struct stack stack; /* XXX */ 214148668Sjeff stack_save(&stack); 215149574Spjd CTRSTACK(KTR_LOCK, &stack, 0, 1); 216148668Sjeff } 217140711Sjeff#endif 218140711Sjeff 21975740Salfred if (flags & LK_INTERLOCK) { 22076100Salfred mtx_assert(interlkp, MA_OWNED | MA_NOTRECURSED); 22172200Sbmilekic mtx_unlock(interlkp); 22275740Salfred } 22328345Sdyson 224111463Sjeff if ((flags & (LK_NOWAIT|LK_RELEASE)) == 0) 225111883Sjhb WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, 226167787Sjhb &lkp->lk_interlock->lock_object, 227111883Sjhb "Acquiring lockmgr lock \"%s\"", lkp->lk_wmesg); 228111463Sjeff 22981506Sjhb if (panicstr != NULL) { 23081506Sjhb mtx_unlock(lkp->lk_interlock); 23181506Sjhb return (0); 23281506Sjhb } 233144372Sjeff if ((lkp->lk_flags & LK_NOSHARE) && 234144372Sjeff (flags & LK_TYPE_MASK) == LK_SHARED) { 235144372Sjeff flags &= ~LK_TYPE_MASK; 236144372Sjeff flags |= LK_EXCLUSIVE; 237144372Sjeff } 23824269Speter extflags = (flags | lkp->lk_flags) & LK_EXTFLG_MASK; 23924269Speter 24024269Speter switch (flags & LK_TYPE_MASK) { 24124269Speter 24224269Speter case LK_SHARED: 24344681Sjulian /* 24444681Sjulian * If we are not the exclusive lock holder, we have to block 24544681Sjulian * while there is an exclusive lock holder or while an 24644681Sjulian * exclusive lock request or upgrade request is in progress. 24744681Sjulian * 248130023Stjr * However, if TDP_DEADLKTREAT is set, we override exclusive 24944681Sjulian * lock requests or upgrade requests ( but not the exclusive 25044681Sjulian * lock itself ). 25144681Sjulian */ 252175166Sattilio if (lkp->lk_lockholder != td) { 25372227Sjhb lockflags = LK_HAVE_EXCL; 254130023Stjr if (td != NULL && !(td->td_pflags & TDP_DEADLKTREAT)) 25583420Sjhb lockflags |= LK_WANT_EXCL | LK_WANT_UPGRADE; 256167012Skmacy error = acquire(&lkp, extflags, lockflags, &contested, &waitstart); 25724269Speter if (error) 25824269Speter break; 259144082Sjeff sharelock(td, lkp, 1); 260164159Skmacy if (lkp->lk_sharecount == 1) 261167012Skmacy lock_profile_obtain_lock_success(&lkp->lk_object, contested, waitstart, file, line); 262164159Skmacy 26397540Sjeff#if defined(DEBUG_LOCKS) 264148669Sjeff stack_save(&lkp->lk_stack); 26597540Sjeff#endif 26624269Speter break; 26724269Speter } 26824269Speter /* 26924269Speter * We hold an exclusive lock, so downgrade it to shared. 27024269Speter * An alternative would be to fail with EDEADLK. 27124269Speter */ 272144082Sjeff sharelock(td, lkp, 1); 273164159Skmacy if (lkp->lk_sharecount == 1) 274167012Skmacy lock_profile_obtain_lock_success(&lkp->lk_object, contested, waitstart, file, line); 275102412Scharnier /* FALLTHROUGH downgrade */ 27624269Speter 27724269Speter case LK_DOWNGRADE: 278175166Sattilio KASSERT(lkp->lk_lockholder == td && lkp->lk_exclusivecount != 0, 27975472Salfred ("lockmgr: not holding exclusive lock " 280110414Sjulian "(owner thread (%p) != thread (%p), exlcnt (%d) != 0", 281175166Sattilio lkp->lk_lockholder, td, lkp->lk_exclusivecount)); 282144082Sjeff sharelock(td, lkp, lkp->lk_exclusivecount); 283144082Sjeff COUNT(td, -lkp->lk_exclusivecount); 28424269Speter lkp->lk_exclusivecount = 0; 28524269Speter lkp->lk_flags &= ~LK_HAVE_EXCL; 286110190Sjulian lkp->lk_lockholder = LK_NOPROC; 28724269Speter if (lkp->lk_waitcount) 28824269Speter wakeup((void *)lkp); 28924269Speter break; 29024269Speter 29124269Speter case LK_UPGRADE: 29224269Speter /* 29324269Speter * Upgrade a shared lock to an exclusive one. If another 29424269Speter * shared lock has already requested an upgrade to an 29524269Speter * exclusive lock, our shared lock is released and an 29624269Speter * exclusive lock is requested (which will be granted 29724269Speter * after the upgrade). If we return an error, the file 29824269Speter * will always be unlocked. 29924269Speter */ 300175166Sattilio if (lkp->lk_lockholder == td) 30124269Speter panic("lockmgr: upgrade exclusive lock"); 302144928Sjeff if (lkp->lk_sharecount <= 0) 303144928Sjeff panic("lockmgr: upgrade without shared"); 304144082Sjeff shareunlock(td, lkp, 1); 305164159Skmacy if (lkp->lk_sharecount == 0) 306164159Skmacy lock_profile_release_lock(&lkp->lk_object); 30724269Speter /* 30824269Speter * If we are just polling, check to see if we will block. 30924269Speter */ 31024269Speter if ((extflags & LK_NOWAIT) && 31124269Speter ((lkp->lk_flags & LK_WANT_UPGRADE) || 31224269Speter lkp->lk_sharecount > 1)) { 31324269Speter error = EBUSY; 31424269Speter break; 31524269Speter } 31624269Speter if ((lkp->lk_flags & LK_WANT_UPGRADE) == 0) { 31724269Speter /* 31824269Speter * We are first shared lock to request an upgrade, so 31924269Speter * request upgrade and wait for the shared count to 32024269Speter * drop to zero, then take exclusive lock. 32124269Speter */ 32224269Speter lkp->lk_flags |= LK_WANT_UPGRADE; 323167012Skmacy error = acquire(&lkp, extflags, LK_SHARE_NONZERO, &contested, &waitstart); 32424269Speter lkp->lk_flags &= ~LK_WANT_UPGRADE; 32534194Sdyson 326134365Skan if (error) { 327134365Skan if ((lkp->lk_flags & ( LK_WANT_EXCL | LK_WAIT_NONZERO)) == (LK_WANT_EXCL | LK_WAIT_NONZERO)) 328134365Skan wakeup((void *)lkp); 329134365Skan break; 330134365Skan } 331138203Sps if (lkp->lk_exclusivecount != 0) 332138203Sps panic("lockmgr: non-zero exclusive count"); 33324269Speter lkp->lk_flags |= LK_HAVE_EXCL; 334175166Sattilio lkp->lk_lockholder = td; 33524269Speter lkp->lk_exclusivecount = 1; 336144082Sjeff COUNT(td, 1); 337167012Skmacy lock_profile_obtain_lock_success(&lkp->lk_object, contested, waitstart, file, line); 33842900Seivind#if defined(DEBUG_LOCKS) 339148669Sjeff stack_save(&lkp->lk_stack); 34042900Seivind#endif 34124269Speter break; 34224269Speter } 34324269Speter /* 34424269Speter * Someone else has requested upgrade. Release our shared 34524269Speter * lock, awaken upgrade requestor if we are the last shared 34624269Speter * lock, then request an exclusive lock. 34724269Speter */ 34828345Sdyson if ( (lkp->lk_flags & (LK_SHARE_NONZERO|LK_WAIT_NONZERO)) == 34928345Sdyson LK_WAIT_NONZERO) 35024269Speter wakeup((void *)lkp); 351102412Scharnier /* FALLTHROUGH exclusive request */ 35224269Speter 35324269Speter case LK_EXCLUSIVE: 354175166Sattilio if (lkp->lk_lockholder == td) { 35524269Speter /* 35624269Speter * Recursive lock. 35724269Speter */ 35848301Smckusick if ((extflags & (LK_NOWAIT | LK_CANRECURSE)) == 0) 35924269Speter panic("lockmgr: locking against myself"); 36048301Smckusick if ((extflags & LK_CANRECURSE) != 0) { 36148301Smckusick lkp->lk_exclusivecount++; 362144082Sjeff COUNT(td, 1); 36348301Smckusick break; 36448301Smckusick } 36524269Speter } 36624269Speter /* 36724269Speter * If we are just polling, check to see if we will sleep. 36824269Speter */ 36928345Sdyson if ((extflags & LK_NOWAIT) && 37028345Sdyson (lkp->lk_flags & (LK_HAVE_EXCL | LK_WANT_EXCL | LK_WANT_UPGRADE | LK_SHARE_NONZERO))) { 37124269Speter error = EBUSY; 37224269Speter break; 37324269Speter } 37424269Speter /* 37524269Speter * Try to acquire the want_exclusive flag. 37624269Speter */ 377167012Skmacy error = acquire(&lkp, extflags, (LK_HAVE_EXCL | LK_WANT_EXCL), &contested, &waitstart); 37824269Speter if (error) 37924269Speter break; 38024269Speter lkp->lk_flags |= LK_WANT_EXCL; 38124269Speter /* 38224269Speter * Wait for shared locks and upgrades to finish. 38324269Speter */ 384167012Skmacy error = acquire(&lkp, extflags, LK_HAVE_EXCL | LK_WANT_UPGRADE | LK_SHARE_NONZERO, &contested, &waitstart); 38524269Speter lkp->lk_flags &= ~LK_WANT_EXCL; 386134365Skan if (error) { 387134365Skan if (lkp->lk_flags & LK_WAIT_NONZERO) 388134365Skan wakeup((void *)lkp); 38924269Speter break; 390134365Skan } 39124269Speter lkp->lk_flags |= LK_HAVE_EXCL; 392175166Sattilio lkp->lk_lockholder = td; 39324269Speter if (lkp->lk_exclusivecount != 0) 39424269Speter panic("lockmgr: non-zero exclusive count"); 39524269Speter lkp->lk_exclusivecount = 1; 396144082Sjeff COUNT(td, 1); 397167012Skmacy lock_profile_obtain_lock_success(&lkp->lk_object, contested, waitstart, file, line); 39842900Seivind#if defined(DEBUG_LOCKS) 399148669Sjeff stack_save(&lkp->lk_stack); 40042900Seivind#endif 40124269Speter break; 40224269Speter 40324269Speter case LK_RELEASE: 40424269Speter if (lkp->lk_exclusivecount != 0) { 405175166Sattilio if (lkp->lk_lockholder != td && 40651702Sdillon lkp->lk_lockholder != LK_KERNPROC) { 407110414Sjulian panic("lockmgr: thread %p, not %s %p unlocking", 408175166Sattilio td, "exclusive lock holder", 40924269Speter lkp->lk_lockholder); 41051702Sdillon } 411144082Sjeff if (lkp->lk_lockholder != LK_KERNPROC) 412144082Sjeff COUNT(td, -1); 41334194Sdyson if (lkp->lk_exclusivecount == 1) { 41424269Speter lkp->lk_flags &= ~LK_HAVE_EXCL; 41524269Speter lkp->lk_lockholder = LK_NOPROC; 41634194Sdyson lkp->lk_exclusivecount = 0; 417164159Skmacy lock_profile_release_lock(&lkp->lk_object); 41834194Sdyson } else { 41934194Sdyson lkp->lk_exclusivecount--; 42024269Speter } 42171576Sjasone } else if (lkp->lk_flags & LK_SHARE_NONZERO) 422144082Sjeff shareunlock(td, lkp, 1); 423149723Sssouhlal else { 424149723Sssouhlal printf("lockmgr: thread %p unlocking unheld lock\n", 425175166Sattilio td); 426149723Sssouhlal kdb_backtrace(); 427149723Sssouhlal } 428149723Sssouhlal 42928345Sdyson if (lkp->lk_flags & LK_WAIT_NONZERO) 43024269Speter wakeup((void *)lkp); 43124269Speter break; 43224269Speter 43324269Speter case LK_DRAIN: 43424269Speter /* 43524269Speter * Check that we do not already hold the lock, as it can 43624269Speter * never drain if we do. Unfortunately, we have no way to 43724269Speter * check for holding a shared lock, but at least we can 43824269Speter * check for an exclusive one. 43924269Speter */ 440175166Sattilio if (lkp->lk_lockholder == td) 44124269Speter panic("lockmgr: draining against myself"); 44228345Sdyson 44328345Sdyson error = acquiredrain(lkp, extflags); 44428345Sdyson if (error) 44524269Speter break; 44624269Speter lkp->lk_flags |= LK_DRAINING | LK_HAVE_EXCL; 447175166Sattilio lkp->lk_lockholder = td; 44824269Speter lkp->lk_exclusivecount = 1; 449144082Sjeff COUNT(td, 1); 45042900Seivind#if defined(DEBUG_LOCKS) 451148669Sjeff stack_save(&lkp->lk_stack); 45242900Seivind#endif 45324269Speter break; 45424269Speter 45524269Speter default: 45672200Sbmilekic mtx_unlock(lkp->lk_interlock); 45724269Speter panic("lockmgr: unknown locktype request %d", 45824269Speter flags & LK_TYPE_MASK); 45924269Speter /* NOTREACHED */ 46024269Speter } 46128345Sdyson if ((lkp->lk_flags & LK_WAITDRAIN) && 46228345Sdyson (lkp->lk_flags & (LK_HAVE_EXCL | LK_WANT_EXCL | LK_WANT_UPGRADE | 46328345Sdyson LK_SHARE_NONZERO | LK_WAIT_NONZERO)) == 0) { 46424269Speter lkp->lk_flags &= ~LK_WAITDRAIN; 46524269Speter wakeup((void *)&lkp->lk_flags); 46624269Speter } 46772200Sbmilekic mtx_unlock(lkp->lk_interlock); 46824269Speter return (error); 46924269Speter} 47024269Speter 47129653Sdysonstatic int 47229653Sdysonacquiredrain(struct lock *lkp, int extflags) { 47329653Sdyson int error; 47429653Sdyson 47529653Sdyson if ((extflags & LK_NOWAIT) && (lkp->lk_flags & LK_ALL)) { 47629653Sdyson return EBUSY; 47729653Sdyson } 47829653Sdyson while (lkp->lk_flags & LK_ALL) { 47929653Sdyson lkp->lk_flags |= LK_WAITDRAIN; 48069432Sjake error = msleep(&lkp->lk_flags, lkp->lk_interlock, lkp->lk_prio, 48188318Sdillon lkp->lk_wmesg, 48288318Sdillon ((extflags & LK_TIMELOCK) ? lkp->lk_timo : 0)); 48329653Sdyson if (error) 48429653Sdyson return error; 48529653Sdyson if (extflags & LK_SLEEPFAIL) { 48629653Sdyson return ENOLCK; 48729653Sdyson } 48829653Sdyson } 48929653Sdyson return 0; 49029653Sdyson} 49129653Sdyson 49224269Speter/* 49329653Sdyson * Initialize a lock; required before use. 49429653Sdyson */ 49529653Sdysonvoid 49629653Sdysonlockinit(lkp, prio, wmesg, timo, flags) 49729653Sdyson struct lock *lkp; 49829653Sdyson int prio; 49991698Seivind const char *wmesg; 50029653Sdyson int timo; 50129653Sdyson int flags; 50229653Sdyson{ 503112106Sjhb CTR5(KTR_LOCK, "lockinit(): lkp == %p, prio == %d, wmesg == \"%s\", " 50466615Sjasone "timo == %d, flags = 0x%x\n", lkp, prio, wmesg, timo, flags); 50529653Sdyson 506117660Struckman lkp->lk_interlock = mtx_pool_alloc(mtxpool_lockbuilder); 50767046Sjasone lkp->lk_flags = (flags & LK_EXTFLG_MASK); 50829653Sdyson lkp->lk_sharecount = 0; 50929653Sdyson lkp->lk_waitcount = 0; 51029653Sdyson lkp->lk_exclusivecount = 0; 51129653Sdyson lkp->lk_prio = prio; 51229653Sdyson lkp->lk_timo = timo; 51329653Sdyson lkp->lk_lockholder = LK_NOPROC; 514107414Smckusick lkp->lk_newlock = NULL; 515105370Smckusick#ifdef DEBUG_LOCKS 516148669Sjeff stack_zero(&lkp->lk_stack); 517105370Smckusick#endif 518168070Sjhb lock_init(&lkp->lk_object, &lock_class_lockmgr, wmesg, NULL, 519168070Sjhb LO_RECURSABLE | LO_SLEEPABLE | LO_UPGRADABLE); 52029653Sdyson} 52129653Sdyson 52229653Sdyson/* 52366615Sjasone * Destroy a lock. 52466615Sjasone */ 52566615Sjasonevoid 52666615Sjasonelockdestroy(lkp) 52766615Sjasone struct lock *lkp; 52866615Sjasone{ 529169675Sjhb 530112106Sjhb CTR2(KTR_LOCK, "lockdestroy(): lkp == %p (lk_wmesg == \"%s\")", 53166615Sjasone lkp, lkp->lk_wmesg); 532168070Sjhb lock_destroy(&lkp->lk_object); 53366615Sjasone} 53466615Sjasone 53566615Sjasone/* 536175166Sattilio * Disown the lockmgr. 537175166Sattilio */ 538175166Sattiliovoid 539175166Sattiliolockmgr_disown(struct lock *lkp) 540175166Sattilio{ 541175166Sattilio struct thread *td; 542175166Sattilio 543175166Sattilio td = curthread; 544175229Sattilio KASSERT(panicstr != NULL || lkp->lk_exclusivecount, 545175166Sattilio ("%s: %p lockmgr must be exclusively locked", __func__, lkp)); 546175229Sattilio KASSERT(panicstr != NULL || lkp->lk_lockholder == td || 547175229Sattilio lkp->lk_lockholder == LK_KERNPROC, 548175166Sattilio ("%s: %p lockmgr must be locked by curthread (%p)", __func__, lkp, 549175166Sattilio td)); 550175166Sattilio 551175166Sattilio /* 552175166Sattilio * Drop the lock reference and switch the owner. This will result 553175166Sattilio * in an atomic operation like td_lock is only accessed by curthread 554175229Sattilio * and lk_lockholder only needs one write. Note also that the lock 555175229Sattilio * owner can be alredy KERNPROC, so in that case just skip the 556175229Sattilio * decrement. 557175166Sattilio */ 558175166Sattilio if (lkp->lk_lockholder == td) 559175166Sattilio td->td_locks--; 560175166Sattilio lkp->lk_lockholder = LK_KERNPROC; 561175166Sattilio} 562175166Sattilio 563175166Sattilio/* 56429653Sdyson * Determine the status of a lock. 56529653Sdyson */ 56629653Sdysonint 56783366Sjulianlockstatus(lkp, td) 56829653Sdyson struct lock *lkp; 56983366Sjulian struct thread *td; 57029653Sdyson{ 57129653Sdyson int lock_type = 0; 572150646Srwatson int interlocked; 57329653Sdyson 574175635Sattilio KASSERT(td == NULL || td == curthread, 575175635Sattilio ("%s: thread passed argument (%p) is not valid", __func__, td)); 576175635Sattilio 577150646Srwatson if (!kdb_active) { 578150646Srwatson interlocked = 1; 579150646Srwatson mtx_lock(lkp->lk_interlock); 580150646Srwatson } else 581150646Srwatson interlocked = 0; 58254444Seivind if (lkp->lk_exclusivecount != 0) { 583110414Sjulian if (td == NULL || lkp->lk_lockholder == td) 58454444Seivind lock_type = LK_EXCLUSIVE; 58554444Seivind else 58654444Seivind lock_type = LK_EXCLOTHER; 58754444Seivind } else if (lkp->lk_sharecount != 0) 58829653Sdyson lock_type = LK_SHARED; 589150646Srwatson if (interlocked) 590150646Srwatson mtx_unlock(lkp->lk_interlock); 59129653Sdyson return (lock_type); 59229653Sdyson} 59329653Sdyson 59429653Sdyson/* 595162941Stegge * Determine the number of waiters on a lock. 596162941Stegge */ 597162941Steggeint 598162941Steggelockwaiters(lkp) 599162941Stegge struct lock *lkp; 600162941Stegge{ 601162941Stegge int count; 602162941Stegge 603162941Stegge mtx_lock(lkp->lk_interlock); 604162941Stegge count = lkp->lk_waitcount; 605162941Stegge mtx_unlock(lkp->lk_interlock); 606162941Stegge return (count); 607162941Stegge} 608162941Stegge 609162941Stegge/* 61024269Speter * Print out information about state of a lock. Used by VOP_PRINT 61128569Sphk * routines to display status about contained locks. 61224269Speter */ 61324271Spetervoid 61424269Speterlockmgr_printinfo(lkp) 61524269Speter struct lock *lkp; 61624269Speter{ 61724269Speter 61824269Speter if (lkp->lk_sharecount) 61924269Speter printf(" lock type %s: SHARED (count %d)", lkp->lk_wmesg, 62024269Speter lkp->lk_sharecount); 62124269Speter else if (lkp->lk_flags & LK_HAVE_EXCL) 622124163Skan printf(" lock type %s: EXCL (count %d) by thread %p (pid %d)", 623124163Skan lkp->lk_wmesg, lkp->lk_exclusivecount, 624124163Skan lkp->lk_lockholder, lkp->lk_lockholder->td_proc->p_pid); 62524269Speter if (lkp->lk_waitcount > 0) 62624269Speter printf(" with %d pending", lkp->lk_waitcount); 627148669Sjeff#ifdef DEBUG_LOCKS 628174137Srwatson stack_print_ddb(&lkp->lk_stack); 629148669Sjeff#endif 63024269Speter} 631161322Sjhb 632161322Sjhb#ifdef DDB 633161337Sjhb/* 634161337Sjhb * Check to see if a thread that is blocked on a sleep queue is actually 635161337Sjhb * blocked on a 'struct lock'. If so, output some details and return true. 636161337Sjhb * If the lock has an exclusive owner, return that in *ownerp. 637161337Sjhb */ 638161337Sjhbint 639161337Sjhblockmgr_chain(struct thread *td, struct thread **ownerp) 640161337Sjhb{ 641161337Sjhb struct lock *lkp; 642161337Sjhb 643161337Sjhb lkp = td->td_wchan; 644161337Sjhb 645161337Sjhb /* Simple test to see if wchan points to a lockmgr lock. */ 646168070Sjhb if (LOCK_CLASS(&lkp->lk_object) == &lock_class_lockmgr && 647168070Sjhb lkp->lk_wmesg == td->td_wmesg) 648167782Sjhb goto ok; 649161337Sjhb 650167782Sjhb /* 651167782Sjhb * If this thread is doing a DRAIN, then it would be asleep on 652167782Sjhb * &lkp->lk_flags rather than lkp. 653167782Sjhb */ 654167782Sjhb lkp = (struct lock *)((char *)td->td_wchan - 655167782Sjhb offsetof(struct lock, lk_flags)); 656168070Sjhb if (LOCK_CLASS(&lkp->lk_object) == &lock_class_lockmgr && 657168070Sjhb lkp->lk_wmesg == td->td_wmesg && (lkp->lk_flags & LK_WAITDRAIN)) 658167782Sjhb goto ok; 659167782Sjhb 660167782Sjhb /* Doen't seem to be a lockmgr lock. */ 661167782Sjhb return (0); 662167782Sjhb 663167782Sjhbok: 664161337Sjhb /* Ok, we think we have a lockmgr lock, so output some details. */ 665161337Sjhb db_printf("blocked on lk \"%s\" ", lkp->lk_wmesg); 666161337Sjhb if (lkp->lk_sharecount) { 667161337Sjhb db_printf("SHARED (count %d)\n", lkp->lk_sharecount); 668161337Sjhb *ownerp = NULL; 669161337Sjhb } else { 670161337Sjhb db_printf("EXCL (count %d)\n", lkp->lk_exclusivecount); 671161337Sjhb *ownerp = lkp->lk_lockholder; 672161337Sjhb } 673161337Sjhb return (1); 674161337Sjhb} 675161337Sjhb 676164246Skmacyvoid 677164246Skmacydb_show_lockmgr(struct lock_object *lock) 678161322Sjhb{ 679161322Sjhb struct thread *td; 680161322Sjhb struct lock *lkp; 681161322Sjhb 682164246Skmacy lkp = (struct lock *)lock; 683161322Sjhb 684168070Sjhb db_printf(" lock type: %s\n", lkp->lk_wmesg); 685168070Sjhb db_printf(" state: "); 686161322Sjhb if (lkp->lk_sharecount) 687161322Sjhb db_printf("SHARED (count %d)\n", lkp->lk_sharecount); 688161322Sjhb else if (lkp->lk_flags & LK_HAVE_EXCL) { 689161322Sjhb td = lkp->lk_lockholder; 690161322Sjhb db_printf("EXCL (count %d) %p ", lkp->lk_exclusivecount, td); 691161322Sjhb db_printf("(tid %d, pid %d, \"%s\")\n", td->td_tid, 692173600Sjulian td->td_proc->p_pid, td->td_name); 693161322Sjhb } else 694161322Sjhb db_printf("UNLOCKED\n"); 695161322Sjhb if (lkp->lk_waitcount > 0) 696168070Sjhb db_printf(" waiters: %d\n", lkp->lk_waitcount); 697161322Sjhb} 698161322Sjhb#endif 699