kern_lock.c revision 176014
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 176014 2008-02-06 00:37:14Z 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 63176014Sattilio#define LOCKMGR_TRYOP(x) ((x) & LK_NOWAIT) 64176014Sattilio#define LOCKMGR_TRYW(x) (LOCKMGR_TRYOP((x)) ? LOP_TRYLOCK : 0) 65176014Sattilio 66173733Sattiliostatic void assert_lockmgr(struct lock_object *lock, int what); 67161322Sjhb#ifdef DDB 68161322Sjhb#include <ddb/ddb.h> 69164246Skmacystatic void db_show_lockmgr(struct lock_object *lock); 70161322Sjhb#endif 71167368Sjhbstatic void lock_lockmgr(struct lock_object *lock, int how); 72167368Sjhbstatic int unlock_lockmgr(struct lock_object *lock); 73161322Sjhb 74164246Skmacystruct lock_class lock_class_lockmgr = { 75167366Sjhb .lc_name = "lockmgr", 76167366Sjhb .lc_flags = LC_SLEEPLOCK | LC_SLEEPABLE | LC_RECURSABLE | LC_UPGRADABLE, 77173733Sattilio .lc_assert = assert_lockmgr, 78164246Skmacy#ifdef DDB 79167368Sjhb .lc_ddb_show = db_show_lockmgr, 80164246Skmacy#endif 81167368Sjhb .lc_lock = lock_lockmgr, 82167368Sjhb .lc_unlock = unlock_lockmgr, 83164246Skmacy}; 84164246Skmacy 8524269Speter/* 8624269Speter * Locking primitives implementation. 8724269Speter * Locks provide shared/exclusive sychronization. 8824269Speter */ 8924269Speter 90167368Sjhbvoid 91173733Sattilioassert_lockmgr(struct lock_object *lock, int what) 92173733Sattilio{ 93173733Sattilio 94173733Sattilio panic("lockmgr locks do not support assertions"); 95173733Sattilio} 96173733Sattilio 97173733Sattiliovoid 98167368Sjhblock_lockmgr(struct lock_object *lock, int how) 99167368Sjhb{ 100167368Sjhb 101167368Sjhb panic("lockmgr locks do not support sleep interlocking"); 102167368Sjhb} 103167368Sjhb 104167368Sjhbint 105167368Sjhbunlock_lockmgr(struct lock_object *lock) 106167368Sjhb{ 107167368Sjhb 108167368Sjhb panic("lockmgr locks do not support sleep interlocking"); 109167368Sjhb} 110167368Sjhb 111175166Sattilio#define COUNT(td, x) ((td)->td_locks += (x)) 11229653Sdyson#define LK_ALL (LK_HAVE_EXCL | LK_WANT_EXCL | LK_WANT_UPGRADE | \ 11329653Sdyson LK_SHARE_NONZERO | LK_WAIT_NONZERO) 11429653Sdyson 115167012Skmacystatic int acquire(struct lock **lkpp, int extflags, int wanted, int *contested, uint64_t *waittime); 11629653Sdysonstatic int acquiredrain(struct lock *lkp, int extflags) ; 11724269Speter 118144705Sjeffstatic __inline void 119144082Sjeffsharelock(struct thread *td, struct lock *lkp, int incr) { 12028345Sdyson lkp->lk_flags |= LK_SHARE_NONZERO; 12128345Sdyson lkp->lk_sharecount += incr; 122144082Sjeff COUNT(td, incr); 12328345Sdyson} 12424269Speter 125144705Sjeffstatic __inline void 126144082Sjeffshareunlock(struct thread *td, struct lock *lkp, int decr) { 12742453Seivind 12842408Seivind KASSERT(lkp->lk_sharecount >= decr, ("shareunlock: count < decr")); 12924269Speter 130144082Sjeff COUNT(td, -decr); 13134194Sdyson if (lkp->lk_sharecount == decr) { 13228345Sdyson lkp->lk_flags &= ~LK_SHARE_NONZERO; 13334194Sdyson if (lkp->lk_flags & (LK_WANT_UPGRADE | LK_WANT_EXCL)) { 13434194Sdyson wakeup(lkp); 13534194Sdyson } 13634194Sdyson lkp->lk_sharecount = 0; 13734194Sdyson } else { 13834194Sdyson lkp->lk_sharecount -= decr; 13934194Sdyson } 14028345Sdyson} 14128345Sdyson 14228345Sdysonstatic int 143167012Skmacyacquire(struct lock **lkpp, int extflags, int wanted, int *contested, uint64_t *waittime) 144140711Sjeff{ 145107414Smckusick struct lock *lkp = *lkpp; 146144589Sjeff int error; 147112106Sjhb CTR3(KTR_LOCK, 148132587Srwatson "acquire(): lkp == %p, extflags == 0x%x, wanted == 0x%x", 14966615Sjasone lkp, extflags, wanted); 15066615Sjasone 151144589Sjeff if ((extflags & LK_NOWAIT) && (lkp->lk_flags & wanted)) 15228345Sdyson return EBUSY; 153144589Sjeff error = 0; 154167012Skmacy if ((lkp->lk_flags & wanted) != 0) 155167012Skmacy lock_profile_obtain_lock_failed(&lkp->lk_object, contested, waittime); 156167012Skmacy 15728345Sdyson while ((lkp->lk_flags & wanted) != 0) { 158144589Sjeff CTR2(KTR_LOCK, 159144589Sjeff "acquire(): lkp == %p, lk_flags == 0x%x sleeping", 160144589Sjeff lkp, lkp->lk_flags); 16128345Sdyson lkp->lk_flags |= LK_WAIT_NONZERO; 16228345Sdyson lkp->lk_waitcount++; 16369432Sjake error = msleep(lkp, lkp->lk_interlock, lkp->lk_prio, 16488318Sdillon lkp->lk_wmesg, 16588318Sdillon ((extflags & LK_TIMELOCK) ? lkp->lk_timo : 0)); 166144589Sjeff lkp->lk_waitcount--; 167144589Sjeff if (lkp->lk_waitcount == 0) 16828345Sdyson lkp->lk_flags &= ~LK_WAIT_NONZERO; 169144589Sjeff if (error) 170144589Sjeff break; 17128345Sdyson if (extflags & LK_SLEEPFAIL) { 172144589Sjeff error = ENOLCK; 173144589Sjeff break; 17428345Sdyson } 175107414Smckusick if (lkp->lk_newlock != NULL) { 176107414Smckusick mtx_lock(lkp->lk_newlock->lk_interlock); 177107414Smckusick mtx_unlock(lkp->lk_interlock); 178107414Smckusick if (lkp->lk_waitcount == 0) 179107414Smckusick wakeup((void *)(&lkp->lk_newlock)); 180107414Smckusick *lkpp = lkp = lkp->lk_newlock; 181107414Smckusick } 18228345Sdyson } 183144589Sjeff mtx_assert(lkp->lk_interlock, MA_OWNED); 184144589Sjeff return (error); 18528345Sdyson} 18628345Sdyson 18724269Speter/* 18824269Speter * Set, change, or release a lock. 18924269Speter * 19024269Speter * Shared requests increment the shared count. Exclusive requests set the 19124269Speter * LK_WANT_EXCL flag (preventing further shared locks), and wait for already 19224269Speter * accepted shared locks and shared-to-exclusive upgrades to go away. 19324269Speter */ 19424269Speterint 195175635Sattilio_lockmgr(struct lock *lkp, u_int flags, struct mtx *interlkp, char *file, 196175635Sattilio int line) 197164159Skmacy 19824269Speter{ 199175635Sattilio struct thread *td; 20024269Speter int error; 20172227Sjhb int extflags, lockflags; 202167012Skmacy int contested = 0; 203167012Skmacy uint64_t waitstart = 0; 204174948Sattilio 20524269Speter error = 0; 206175635Sattilio td = curthread; 20728345Sdyson 208111463Sjeff if ((flags & LK_INTERNAL) == 0) 209111463Sjeff mtx_lock(lkp->lk_interlock); 210140711Sjeff CTR6(KTR_LOCK, 211140711Sjeff "lockmgr(): lkp == %p (lk_wmesg == \"%s\"), owner == %p, exclusivecount == %d, flags == 0x%x, " 212140711Sjeff "td == %p", lkp, lkp->lk_wmesg, lkp->lk_lockholder, 213140711Sjeff lkp->lk_exclusivecount, flags, td); 214148668Sjeff#ifdef DEBUG_LOCKS 215148668Sjeff { 216148668Sjeff struct stack stack; /* XXX */ 217148668Sjeff stack_save(&stack); 218149574Spjd CTRSTACK(KTR_LOCK, &stack, 0, 1); 219148668Sjeff } 220140711Sjeff#endif 221140711Sjeff 22275740Salfred if (flags & LK_INTERLOCK) { 22376100Salfred mtx_assert(interlkp, MA_OWNED | MA_NOTRECURSED); 22472200Sbmilekic mtx_unlock(interlkp); 22575740Salfred } 22628345Sdyson 227111463Sjeff if ((flags & (LK_NOWAIT|LK_RELEASE)) == 0) 228111883Sjhb WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, 229167787Sjhb &lkp->lk_interlock->lock_object, 230111883Sjhb "Acquiring lockmgr lock \"%s\"", lkp->lk_wmesg); 231111463Sjeff 23281506Sjhb if (panicstr != NULL) { 23381506Sjhb mtx_unlock(lkp->lk_interlock); 23481506Sjhb return (0); 23581506Sjhb } 236144372Sjeff if ((lkp->lk_flags & LK_NOSHARE) && 237144372Sjeff (flags & LK_TYPE_MASK) == LK_SHARED) { 238144372Sjeff flags &= ~LK_TYPE_MASK; 239144372Sjeff flags |= LK_EXCLUSIVE; 240144372Sjeff } 24124269Speter extflags = (flags | lkp->lk_flags) & LK_EXTFLG_MASK; 24224269Speter 24324269Speter switch (flags & LK_TYPE_MASK) { 24424269Speter 24524269Speter case LK_SHARED: 246176014Sattilio if (!LOCKMGR_TRYOP(extflags)) 247176014Sattilio WITNESS_CHECKORDER(&lkp->lk_object, LOP_NEWORDER, file, 248176014Sattilio line); 24944681Sjulian /* 25044681Sjulian * If we are not the exclusive lock holder, we have to block 25144681Sjulian * while there is an exclusive lock holder or while an 25244681Sjulian * exclusive lock request or upgrade request is in progress. 25344681Sjulian * 254130023Stjr * However, if TDP_DEADLKTREAT is set, we override exclusive 25544681Sjulian * lock requests or upgrade requests ( but not the exclusive 25644681Sjulian * lock itself ). 25744681Sjulian */ 258175166Sattilio if (lkp->lk_lockholder != td) { 25972227Sjhb lockflags = LK_HAVE_EXCL; 260130023Stjr if (td != NULL && !(td->td_pflags & TDP_DEADLKTREAT)) 26183420Sjhb lockflags |= LK_WANT_EXCL | LK_WANT_UPGRADE; 262167012Skmacy error = acquire(&lkp, extflags, lockflags, &contested, &waitstart); 26324269Speter if (error) 26424269Speter break; 265144082Sjeff sharelock(td, lkp, 1); 266164159Skmacy if (lkp->lk_sharecount == 1) 267167012Skmacy lock_profile_obtain_lock_success(&lkp->lk_object, contested, waitstart, file, line); 268176014Sattilio WITNESS_LOCK(&lkp->lk_object, LOCKMGR_TRYW(extflags), 269176014Sattilio file, line); 270164159Skmacy 27197540Sjeff#if defined(DEBUG_LOCKS) 272148669Sjeff stack_save(&lkp->lk_stack); 27397540Sjeff#endif 27424269Speter break; 27524269Speter } 27624269Speter /* 27724269Speter * We hold an exclusive lock, so downgrade it to shared. 27824269Speter * An alternative would be to fail with EDEADLK. 27924269Speter */ 280102412Scharnier /* FALLTHROUGH downgrade */ 28124269Speter 28224269Speter case LK_DOWNGRADE: 283175166Sattilio KASSERT(lkp->lk_lockholder == td && lkp->lk_exclusivecount != 0, 28475472Salfred ("lockmgr: not holding exclusive lock " 285110414Sjulian "(owner thread (%p) != thread (%p), exlcnt (%d) != 0", 286175166Sattilio lkp->lk_lockholder, td, lkp->lk_exclusivecount)); 287144082Sjeff sharelock(td, lkp, lkp->lk_exclusivecount); 288176014Sattilio WITNESS_DOWNGRADE(&lkp->lk_object, 0, file, line); 289144082Sjeff COUNT(td, -lkp->lk_exclusivecount); 29024269Speter lkp->lk_exclusivecount = 0; 29124269Speter lkp->lk_flags &= ~LK_HAVE_EXCL; 292110190Sjulian lkp->lk_lockholder = LK_NOPROC; 29324269Speter if (lkp->lk_waitcount) 29424269Speter wakeup((void *)lkp); 29524269Speter break; 29624269Speter 29724269Speter case LK_UPGRADE: 29824269Speter /* 29924269Speter * Upgrade a shared lock to an exclusive one. If another 30024269Speter * shared lock has already requested an upgrade to an 30124269Speter * exclusive lock, our shared lock is released and an 30224269Speter * exclusive lock is requested (which will be granted 30324269Speter * after the upgrade). If we return an error, the file 30424269Speter * will always be unlocked. 30524269Speter */ 306175166Sattilio if (lkp->lk_lockholder == td) 30724269Speter panic("lockmgr: upgrade exclusive lock"); 308144928Sjeff if (lkp->lk_sharecount <= 0) 309144928Sjeff panic("lockmgr: upgrade without shared"); 310144082Sjeff shareunlock(td, lkp, 1); 311164159Skmacy if (lkp->lk_sharecount == 0) 312164159Skmacy lock_profile_release_lock(&lkp->lk_object); 31324269Speter /* 31424269Speter * If we are just polling, check to see if we will block. 31524269Speter */ 31624269Speter if ((extflags & LK_NOWAIT) && 31724269Speter ((lkp->lk_flags & LK_WANT_UPGRADE) || 31824269Speter lkp->lk_sharecount > 1)) { 31924269Speter error = EBUSY; 320176014Sattilio WITNESS_UNLOCK(&lkp->lk_object, 0, file, line); 32124269Speter break; 32224269Speter } 32324269Speter if ((lkp->lk_flags & LK_WANT_UPGRADE) == 0) { 32424269Speter /* 32524269Speter * We are first shared lock to request an upgrade, so 32624269Speter * request upgrade and wait for the shared count to 32724269Speter * drop to zero, then take exclusive lock. 32824269Speter */ 32924269Speter lkp->lk_flags |= LK_WANT_UPGRADE; 330167012Skmacy error = acquire(&lkp, extflags, LK_SHARE_NONZERO, &contested, &waitstart); 33124269Speter lkp->lk_flags &= ~LK_WANT_UPGRADE; 33234194Sdyson 333134365Skan if (error) { 334134365Skan if ((lkp->lk_flags & ( LK_WANT_EXCL | LK_WAIT_NONZERO)) == (LK_WANT_EXCL | LK_WAIT_NONZERO)) 335134365Skan wakeup((void *)lkp); 336176014Sattilio WITNESS_UNLOCK(&lkp->lk_object, 0, file, line); 337134365Skan break; 338134365Skan } 339138203Sps if (lkp->lk_exclusivecount != 0) 340138203Sps panic("lockmgr: non-zero exclusive count"); 34124269Speter lkp->lk_flags |= LK_HAVE_EXCL; 342175166Sattilio lkp->lk_lockholder = td; 34324269Speter lkp->lk_exclusivecount = 1; 344176014Sattilio WITNESS_UPGRADE(&lkp->lk_object, LOP_EXCLUSIVE | 345176014Sattilio LOP_TRYLOCK, file, line); 346144082Sjeff COUNT(td, 1); 347167012Skmacy lock_profile_obtain_lock_success(&lkp->lk_object, contested, waitstart, file, line); 34842900Seivind#if defined(DEBUG_LOCKS) 349148669Sjeff stack_save(&lkp->lk_stack); 35042900Seivind#endif 35124269Speter break; 35224269Speter } 35324269Speter /* 35424269Speter * Someone else has requested upgrade. Release our shared 35524269Speter * lock, awaken upgrade requestor if we are the last shared 35624269Speter * lock, then request an exclusive lock. 35724269Speter */ 358176014Sattilio WITNESS_UNLOCK(&lkp->lk_object, 0, file, line); 35928345Sdyson if ( (lkp->lk_flags & (LK_SHARE_NONZERO|LK_WAIT_NONZERO)) == 36028345Sdyson LK_WAIT_NONZERO) 36124269Speter wakeup((void *)lkp); 362102412Scharnier /* FALLTHROUGH exclusive request */ 36324269Speter 36424269Speter case LK_EXCLUSIVE: 365176014Sattilio if (!LOCKMGR_TRYOP(extflags)) 366176014Sattilio WITNESS_CHECKORDER(&lkp->lk_object, LOP_NEWORDER | 367176014Sattilio LOP_EXCLUSIVE, file, line); 368175166Sattilio if (lkp->lk_lockholder == td) { 36924269Speter /* 37024269Speter * Recursive lock. 37124269Speter */ 37248301Smckusick if ((extflags & (LK_NOWAIT | LK_CANRECURSE)) == 0) 37324269Speter panic("lockmgr: locking against myself"); 37448301Smckusick if ((extflags & LK_CANRECURSE) != 0) { 37548301Smckusick lkp->lk_exclusivecount++; 376176014Sattilio WITNESS_LOCK(&lkp->lk_object, LOP_EXCLUSIVE | 377176014Sattilio LOCKMGR_TRYW(extflags), file, line); 378144082Sjeff COUNT(td, 1); 37948301Smckusick break; 38048301Smckusick } 38124269Speter } 38224269Speter /* 38324269Speter * If we are just polling, check to see if we will sleep. 38424269Speter */ 38528345Sdyson if ((extflags & LK_NOWAIT) && 38628345Sdyson (lkp->lk_flags & (LK_HAVE_EXCL | LK_WANT_EXCL | LK_WANT_UPGRADE | LK_SHARE_NONZERO))) { 38724269Speter error = EBUSY; 38824269Speter break; 38924269Speter } 39024269Speter /* 39124269Speter * Try to acquire the want_exclusive flag. 39224269Speter */ 393167012Skmacy error = acquire(&lkp, extflags, (LK_HAVE_EXCL | LK_WANT_EXCL), &contested, &waitstart); 39424269Speter if (error) 39524269Speter break; 39624269Speter lkp->lk_flags |= LK_WANT_EXCL; 39724269Speter /* 39824269Speter * Wait for shared locks and upgrades to finish. 39924269Speter */ 400167012Skmacy error = acquire(&lkp, extflags, LK_HAVE_EXCL | LK_WANT_UPGRADE | LK_SHARE_NONZERO, &contested, &waitstart); 40124269Speter lkp->lk_flags &= ~LK_WANT_EXCL; 402134365Skan if (error) { 403134365Skan if (lkp->lk_flags & LK_WAIT_NONZERO) 404134365Skan wakeup((void *)lkp); 40524269Speter break; 406134365Skan } 40724269Speter lkp->lk_flags |= LK_HAVE_EXCL; 408175166Sattilio lkp->lk_lockholder = td; 40924269Speter if (lkp->lk_exclusivecount != 0) 41024269Speter panic("lockmgr: non-zero exclusive count"); 41124269Speter lkp->lk_exclusivecount = 1; 412176014Sattilio WITNESS_LOCK(&lkp->lk_object, LOP_EXCLUSIVE | 413176014Sattilio LOCKMGR_TRYW(extflags), file, line); 414144082Sjeff COUNT(td, 1); 415167012Skmacy lock_profile_obtain_lock_success(&lkp->lk_object, contested, waitstart, file, line); 41642900Seivind#if defined(DEBUG_LOCKS) 417148669Sjeff stack_save(&lkp->lk_stack); 41842900Seivind#endif 41924269Speter break; 42024269Speter 42124269Speter case LK_RELEASE: 42224269Speter if (lkp->lk_exclusivecount != 0) { 423175166Sattilio if (lkp->lk_lockholder != td && 42451702Sdillon lkp->lk_lockholder != LK_KERNPROC) { 425110414Sjulian panic("lockmgr: thread %p, not %s %p unlocking", 426175166Sattilio td, "exclusive lock holder", 42724269Speter lkp->lk_lockholder); 42851702Sdillon } 429176014Sattilio if (lkp->lk_lockholder != LK_KERNPROC) { 430176014Sattilio WITNESS_UNLOCK(&lkp->lk_object, LOP_EXCLUSIVE, 431176014Sattilio file, line); 432144082Sjeff COUNT(td, -1); 433176014Sattilio } 43434194Sdyson if (lkp->lk_exclusivecount == 1) { 43524269Speter lkp->lk_flags &= ~LK_HAVE_EXCL; 43624269Speter lkp->lk_lockholder = LK_NOPROC; 43734194Sdyson lkp->lk_exclusivecount = 0; 438164159Skmacy lock_profile_release_lock(&lkp->lk_object); 43934194Sdyson } else { 44034194Sdyson lkp->lk_exclusivecount--; 44124269Speter } 442176014Sattilio } else if (lkp->lk_flags & LK_SHARE_NONZERO) { 443176014Sattilio WITNESS_UNLOCK(&lkp->lk_object, 0, file, line); 444144082Sjeff shareunlock(td, lkp, 1); 445176014Sattilio } else { 446149723Sssouhlal printf("lockmgr: thread %p unlocking unheld lock\n", 447175166Sattilio td); 448149723Sssouhlal kdb_backtrace(); 449149723Sssouhlal } 450149723Sssouhlal 45128345Sdyson if (lkp->lk_flags & LK_WAIT_NONZERO) 45224269Speter wakeup((void *)lkp); 45324269Speter break; 45424269Speter 45524269Speter case LK_DRAIN: 45624269Speter /* 45724269Speter * Check that we do not already hold the lock, as it can 45824269Speter * never drain if we do. Unfortunately, we have no way to 45924269Speter * check for holding a shared lock, but at least we can 46024269Speter * check for an exclusive one. 46124269Speter */ 462176014Sattilio if (!LOCKMGR_TRYOP(extflags)) 463176014Sattilio WITNESS_CHECKORDER(&lkp->lk_object, LOP_NEWORDER | 464176014Sattilio LOP_EXCLUSIVE, file, line); 465175166Sattilio if (lkp->lk_lockholder == td) 46624269Speter panic("lockmgr: draining against myself"); 46728345Sdyson 46828345Sdyson error = acquiredrain(lkp, extflags); 46928345Sdyson if (error) 47024269Speter break; 47124269Speter lkp->lk_flags |= LK_DRAINING | LK_HAVE_EXCL; 472175166Sattilio lkp->lk_lockholder = td; 47324269Speter lkp->lk_exclusivecount = 1; 474176014Sattilio WITNESS_LOCK(&lkp->lk_object, LOP_EXCLUSIVE | 475176014Sattilio LOCKMGR_TRYW(extflags), file, line); 476144082Sjeff COUNT(td, 1); 47742900Seivind#if defined(DEBUG_LOCKS) 478148669Sjeff stack_save(&lkp->lk_stack); 47942900Seivind#endif 48024269Speter break; 48124269Speter 48224269Speter default: 48372200Sbmilekic mtx_unlock(lkp->lk_interlock); 48424269Speter panic("lockmgr: unknown locktype request %d", 48524269Speter flags & LK_TYPE_MASK); 48624269Speter /* NOTREACHED */ 48724269Speter } 48828345Sdyson if ((lkp->lk_flags & LK_WAITDRAIN) && 48928345Sdyson (lkp->lk_flags & (LK_HAVE_EXCL | LK_WANT_EXCL | LK_WANT_UPGRADE | 49028345Sdyson LK_SHARE_NONZERO | LK_WAIT_NONZERO)) == 0) { 49124269Speter lkp->lk_flags &= ~LK_WAITDRAIN; 49224269Speter wakeup((void *)&lkp->lk_flags); 49324269Speter } 49472200Sbmilekic mtx_unlock(lkp->lk_interlock); 49524269Speter return (error); 49624269Speter} 49724269Speter 49829653Sdysonstatic int 49929653Sdysonacquiredrain(struct lock *lkp, int extflags) { 50029653Sdyson int error; 50129653Sdyson 50229653Sdyson if ((extflags & LK_NOWAIT) && (lkp->lk_flags & LK_ALL)) { 50329653Sdyson return EBUSY; 50429653Sdyson } 50529653Sdyson while (lkp->lk_flags & LK_ALL) { 50629653Sdyson lkp->lk_flags |= LK_WAITDRAIN; 50769432Sjake error = msleep(&lkp->lk_flags, lkp->lk_interlock, lkp->lk_prio, 50888318Sdillon lkp->lk_wmesg, 50988318Sdillon ((extflags & LK_TIMELOCK) ? lkp->lk_timo : 0)); 51029653Sdyson if (error) 51129653Sdyson return error; 51229653Sdyson if (extflags & LK_SLEEPFAIL) { 51329653Sdyson return ENOLCK; 51429653Sdyson } 51529653Sdyson } 51629653Sdyson return 0; 51729653Sdyson} 51829653Sdyson 51924269Speter/* 52029653Sdyson * Initialize a lock; required before use. 52129653Sdyson */ 52229653Sdysonvoid 52329653Sdysonlockinit(lkp, prio, wmesg, timo, flags) 52429653Sdyson struct lock *lkp; 52529653Sdyson int prio; 52691698Seivind const char *wmesg; 52729653Sdyson int timo; 52829653Sdyson int flags; 52929653Sdyson{ 530176014Sattilio int iflags; 531176014Sattilio 532112106Sjhb CTR5(KTR_LOCK, "lockinit(): lkp == %p, prio == %d, wmesg == \"%s\", " 53366615Sjasone "timo == %d, flags = 0x%x\n", lkp, prio, wmesg, timo, flags); 53429653Sdyson 535117660Struckman lkp->lk_interlock = mtx_pool_alloc(mtxpool_lockbuilder); 536176014Sattilio lkp->lk_flags = (flags & LK_EXTFLG_MASK) & ~(LK_NOWITNESS | LK_NODUP); 53729653Sdyson lkp->lk_sharecount = 0; 53829653Sdyson lkp->lk_waitcount = 0; 53929653Sdyson lkp->lk_exclusivecount = 0; 54029653Sdyson lkp->lk_prio = prio; 54129653Sdyson lkp->lk_timo = timo; 54229653Sdyson lkp->lk_lockholder = LK_NOPROC; 543107414Smckusick lkp->lk_newlock = NULL; 544176014Sattilio iflags = LO_RECURSABLE | LO_SLEEPABLE | LO_UPGRADABLE; 545176014Sattilio if (!(flags & LK_NODUP)) 546176014Sattilio iflags |= LO_DUPOK; 547176014Sattilio if (!(flags & LK_NOWITNESS)) 548176014Sattilio iflags |= LO_WITNESS; 549105370Smckusick#ifdef DEBUG_LOCKS 550148669Sjeff stack_zero(&lkp->lk_stack); 551105370Smckusick#endif 552176014Sattilio lock_init(&lkp->lk_object, &lock_class_lockmgr, wmesg, NULL, iflags); 55329653Sdyson} 55429653Sdyson 55529653Sdyson/* 55666615Sjasone * Destroy a lock. 55766615Sjasone */ 55866615Sjasonevoid 55966615Sjasonelockdestroy(lkp) 56066615Sjasone struct lock *lkp; 56166615Sjasone{ 562169675Sjhb 563112106Sjhb CTR2(KTR_LOCK, "lockdestroy(): lkp == %p (lk_wmesg == \"%s\")", 56466615Sjasone lkp, lkp->lk_wmesg); 565168070Sjhb lock_destroy(&lkp->lk_object); 56666615Sjasone} 56766615Sjasone 56866615Sjasone/* 569175166Sattilio * Disown the lockmgr. 570175166Sattilio */ 571175166Sattiliovoid 572176014Sattilio_lockmgr_disown(struct lock *lkp, const char *file, int line) 573175166Sattilio{ 574175166Sattilio struct thread *td; 575175166Sattilio 576175166Sattilio td = curthread; 577175229Sattilio KASSERT(panicstr != NULL || lkp->lk_exclusivecount, 578175166Sattilio ("%s: %p lockmgr must be exclusively locked", __func__, lkp)); 579175229Sattilio KASSERT(panicstr != NULL || lkp->lk_lockholder == td || 580175229Sattilio lkp->lk_lockholder == LK_KERNPROC, 581175166Sattilio ("%s: %p lockmgr must be locked by curthread (%p)", __func__, lkp, 582175166Sattilio td)); 583175166Sattilio 584175166Sattilio /* 585175166Sattilio * Drop the lock reference and switch the owner. This will result 586175166Sattilio * in an atomic operation like td_lock is only accessed by curthread 587175229Sattilio * and lk_lockholder only needs one write. Note also that the lock 588175229Sattilio * owner can be alredy KERNPROC, so in that case just skip the 589175229Sattilio * decrement. 590175166Sattilio */ 591176014Sattilio if (lkp->lk_lockholder == td) { 592176014Sattilio WITNESS_UNLOCK(&lkp->lk_object, LOP_EXCLUSIVE, file, line); 593175166Sattilio td->td_locks--; 594176014Sattilio } 595175166Sattilio lkp->lk_lockholder = LK_KERNPROC; 596175166Sattilio} 597175166Sattilio 598175166Sattilio/* 59929653Sdyson * Determine the status of a lock. 60029653Sdyson */ 60129653Sdysonint 60283366Sjulianlockstatus(lkp, td) 60329653Sdyson struct lock *lkp; 60483366Sjulian struct thread *td; 60529653Sdyson{ 60629653Sdyson int lock_type = 0; 607150646Srwatson int interlocked; 60829653Sdyson 609175635Sattilio KASSERT(td == NULL || td == curthread, 610175635Sattilio ("%s: thread passed argument (%p) is not valid", __func__, td)); 611175635Sattilio 612150646Srwatson if (!kdb_active) { 613150646Srwatson interlocked = 1; 614150646Srwatson mtx_lock(lkp->lk_interlock); 615150646Srwatson } else 616150646Srwatson interlocked = 0; 61754444Seivind if (lkp->lk_exclusivecount != 0) { 618110414Sjulian if (td == NULL || lkp->lk_lockholder == td) 61954444Seivind lock_type = LK_EXCLUSIVE; 62054444Seivind else 62154444Seivind lock_type = LK_EXCLOTHER; 62254444Seivind } else if (lkp->lk_sharecount != 0) 62329653Sdyson lock_type = LK_SHARED; 624150646Srwatson if (interlocked) 625150646Srwatson mtx_unlock(lkp->lk_interlock); 62629653Sdyson return (lock_type); 62729653Sdyson} 62829653Sdyson 62929653Sdyson/* 630162941Stegge * Determine the number of waiters on a lock. 631162941Stegge */ 632162941Steggeint 633162941Steggelockwaiters(lkp) 634162941Stegge struct lock *lkp; 635162941Stegge{ 636162941Stegge int count; 637162941Stegge 638162941Stegge mtx_lock(lkp->lk_interlock); 639162941Stegge count = lkp->lk_waitcount; 640162941Stegge mtx_unlock(lkp->lk_interlock); 641162941Stegge return (count); 642162941Stegge} 643162941Stegge 644162941Stegge/* 64524269Speter * Print out information about state of a lock. Used by VOP_PRINT 64628569Sphk * routines to display status about contained locks. 64724269Speter */ 64824271Spetervoid 64924269Speterlockmgr_printinfo(lkp) 65024269Speter struct lock *lkp; 65124269Speter{ 65224269Speter 65324269Speter if (lkp->lk_sharecount) 65424269Speter printf(" lock type %s: SHARED (count %d)", lkp->lk_wmesg, 65524269Speter lkp->lk_sharecount); 65624269Speter else if (lkp->lk_flags & LK_HAVE_EXCL) 657124163Skan printf(" lock type %s: EXCL (count %d) by thread %p (pid %d)", 658124163Skan lkp->lk_wmesg, lkp->lk_exclusivecount, 659124163Skan lkp->lk_lockholder, lkp->lk_lockholder->td_proc->p_pid); 66024269Speter if (lkp->lk_waitcount > 0) 66124269Speter printf(" with %d pending", lkp->lk_waitcount); 662148669Sjeff#ifdef DEBUG_LOCKS 663174137Srwatson stack_print_ddb(&lkp->lk_stack); 664148669Sjeff#endif 66524269Speter} 666161322Sjhb 667161322Sjhb#ifdef DDB 668161337Sjhb/* 669161337Sjhb * Check to see if a thread that is blocked on a sleep queue is actually 670161337Sjhb * blocked on a 'struct lock'. If so, output some details and return true. 671161337Sjhb * If the lock has an exclusive owner, return that in *ownerp. 672161337Sjhb */ 673161337Sjhbint 674161337Sjhblockmgr_chain(struct thread *td, struct thread **ownerp) 675161337Sjhb{ 676161337Sjhb struct lock *lkp; 677161337Sjhb 678161337Sjhb lkp = td->td_wchan; 679161337Sjhb 680161337Sjhb /* Simple test to see if wchan points to a lockmgr lock. */ 681168070Sjhb if (LOCK_CLASS(&lkp->lk_object) == &lock_class_lockmgr && 682168070Sjhb lkp->lk_wmesg == td->td_wmesg) 683167782Sjhb goto ok; 684161337Sjhb 685167782Sjhb /* 686167782Sjhb * If this thread is doing a DRAIN, then it would be asleep on 687167782Sjhb * &lkp->lk_flags rather than lkp. 688167782Sjhb */ 689167782Sjhb lkp = (struct lock *)((char *)td->td_wchan - 690167782Sjhb offsetof(struct lock, lk_flags)); 691168070Sjhb if (LOCK_CLASS(&lkp->lk_object) == &lock_class_lockmgr && 692168070Sjhb lkp->lk_wmesg == td->td_wmesg && (lkp->lk_flags & LK_WAITDRAIN)) 693167782Sjhb goto ok; 694167782Sjhb 695167782Sjhb /* Doen't seem to be a lockmgr lock. */ 696167782Sjhb return (0); 697167782Sjhb 698167782Sjhbok: 699161337Sjhb /* Ok, we think we have a lockmgr lock, so output some details. */ 700161337Sjhb db_printf("blocked on lk \"%s\" ", lkp->lk_wmesg); 701161337Sjhb if (lkp->lk_sharecount) { 702161337Sjhb db_printf("SHARED (count %d)\n", lkp->lk_sharecount); 703161337Sjhb *ownerp = NULL; 704161337Sjhb } else { 705161337Sjhb db_printf("EXCL (count %d)\n", lkp->lk_exclusivecount); 706161337Sjhb *ownerp = lkp->lk_lockholder; 707161337Sjhb } 708161337Sjhb return (1); 709161337Sjhb} 710161337Sjhb 711164246Skmacyvoid 712164246Skmacydb_show_lockmgr(struct lock_object *lock) 713161322Sjhb{ 714161322Sjhb struct thread *td; 715161322Sjhb struct lock *lkp; 716161322Sjhb 717164246Skmacy lkp = (struct lock *)lock; 718161322Sjhb 719168070Sjhb db_printf(" lock type: %s\n", lkp->lk_wmesg); 720168070Sjhb db_printf(" state: "); 721161322Sjhb if (lkp->lk_sharecount) 722161322Sjhb db_printf("SHARED (count %d)\n", lkp->lk_sharecount); 723161322Sjhb else if (lkp->lk_flags & LK_HAVE_EXCL) { 724161322Sjhb td = lkp->lk_lockholder; 725161322Sjhb db_printf("EXCL (count %d) %p ", lkp->lk_exclusivecount, td); 726161322Sjhb db_printf("(tid %d, pid %d, \"%s\")\n", td->td_tid, 727173600Sjulian td->td_proc->p_pid, td->td_name); 728161322Sjhb } else 729161322Sjhb db_printf("UNLOCKED\n"); 730161322Sjhb if (lkp->lk_waitcount > 0) 731168070Sjhb db_printf(" waiters: %d\n", lkp->lk_waitcount); 732161322Sjhb} 733161322Sjhb#endif 734