lock.h revision 70140
1/* 2 * Copyright (c) 1995 3 * The Regents of the University of California. All rights reserved. 4 * 5 * This code contains ideas from software contributed to Berkeley by 6 * Avadis Tevanian, Jr., Michael Wayne Young, and the Mach Operating 7 * System project at Carnegie-Mellon University. 8 * 9 * Redistribution and use in source and binary forms, with or without 10 * modification, are permitted provided that the following conditions 11 * are met: 12 * 1. Redistributions of source code must retain the above copyright 13 * notice, this list of conditions and the following disclaimer. 14 * 2. Redistributions in binary form must reproduce the above copyright 15 * notice, this list of conditions and the following disclaimer in the 16 * documentation and/or other materials provided with the distribution. 17 * 3. All advertising materials mentioning features or use of this software 18 * must display the following acknowledgement: 19 * This product includes software developed by the University of 20 * California, Berkeley and its contributors. 21 * 4. Neither the name of the University nor the names of its contributors 22 * may be used to endorse or promote products derived from this software 23 * without specific prior written permission. 24 * 25 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 26 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 27 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 28 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 29 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 30 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 31 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 32 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 33 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 34 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 35 * SUCH DAMAGE. 36 * 37 * @(#)lock.h 8.12 (Berkeley) 5/19/95 38 * $FreeBSD: head/sys/sys/lock.h 70140 2000-12-18 05:50:31Z jake $ 39 */ 40 41#ifndef _LOCK_H_ 42#define _LOCK_H_ 43 44#include <machine/lock.h> 45 46struct mtx; 47 48/* 49 * The general lock structure. Provides for multiple shared locks, 50 * upgrading from shared to exclusive, and sleeping until the lock 51 * can be gained. The simple locks are defined in <machine/param.h>. 52 */ 53struct lock { 54 struct mtx *lk_interlock; /* lock on remaining fields */ 55 u_int lk_flags; /* see below */ 56 int lk_sharecount; /* # of accepted shared locks */ 57 int lk_waitcount; /* # of processes sleeping for lock */ 58 short lk_exclusivecount; /* # of recursive exclusive locks */ 59 short lk_prio; /* priority at which to sleep */ 60 char *lk_wmesg; /* resource sleeping (for tsleep) */ 61 int lk_timo; /* maximum sleep time (for tsleep) */ 62 pid_t lk_lockholder; /* pid of exclusive lock holder */ 63#ifdef DEBUG_LOCKS 64 const char *lk_filename; 65 const char *lk_lockername; 66 int lk_lineno; 67#endif 68}; 69/* 70 * Lock request types: 71 * LK_SHARED - get one of many possible shared locks. If a process 72 * holding an exclusive lock requests a shared lock, the exclusive 73 * lock(s) will be downgraded to shared locks. 74 * LK_EXCLUSIVE - stop further shared locks, when they are cleared, 75 * grant a pending upgrade if it exists, then grant an exclusive 76 * lock. Only one exclusive lock may exist at a time, except that 77 * a process holding an exclusive lock may get additional exclusive 78 * locks if it explicitly sets the LK_CANRECURSE flag in the lock 79 * request, or if the LK_CANRECUSE flag was set when the lock was 80 * initialized. 81 * LK_UPGRADE - the process must hold a shared lock that it wants to 82 * have upgraded to an exclusive lock. Other processes may get 83 * exclusive access to the resource between the time that the upgrade 84 * is requested and the time that it is granted. 85 * LK_EXCLUPGRADE - the process must hold a shared lock that it wants to 86 * have upgraded to an exclusive lock. If the request succeeds, no 87 * other processes will have gotten exclusive access to the resource 88 * between the time that the upgrade is requested and the time that 89 * it is granted. However, if another process has already requested 90 * an upgrade, the request will fail (see error returns below). 91 * LK_DOWNGRADE - the process must hold an exclusive lock that it wants 92 * to have downgraded to a shared lock. If the process holds multiple 93 * (recursive) exclusive locks, they will all be downgraded to shared 94 * locks. 95 * LK_RELEASE - release one instance of a lock. 96 * LK_DRAIN - wait for all activity on the lock to end, then mark it 97 * decommissioned. This feature is used before freeing a lock that 98 * is part of a piece of memory that is about to be freed. 99 * LK_EXCLOTHER - return for lockstatus(). Used when another process 100 * holds the lock exclusively. 101 * 102 * These are flags that are passed to the lockmgr routine. 103 */ 104#define LK_TYPE_MASK 0x0000000f /* type of lock sought */ 105#define LK_SHARED 0x00000001 /* shared lock */ 106#define LK_EXCLUSIVE 0x00000002 /* exclusive lock */ 107#define LK_UPGRADE 0x00000003 /* shared-to-exclusive upgrade */ 108#define LK_EXCLUPGRADE 0x00000004 /* first shared-to-exclusive upgrade */ 109#define LK_DOWNGRADE 0x00000005 /* exclusive-to-shared downgrade */ 110#define LK_RELEASE 0x00000006 /* release any type of lock */ 111#define LK_DRAIN 0x00000007 /* wait for all lock activity to end */ 112#define LK_EXCLOTHER 0x00000008 /* other process holds lock */ 113/* 114 * External lock flags. 115 * 116 * The first three flags may be set in lock_init to set their mode permanently, 117 * or passed in as arguments to the lock manager. The LK_REENABLE flag may be 118 * set only at the release of a lock obtained by drain. 119 */ 120#define LK_EXTFLG_MASK 0x01000070 /* mask of external flags */ 121#define LK_NOWAIT 0x00000010 /* do not sleep to await lock */ 122#define LK_SLEEPFAIL 0x00000020 /* sleep, then return failure */ 123#define LK_CANRECURSE 0x00000040 /* allow recursive exclusive lock */ 124#define LK_REENABLE 0x00000080 /* lock is be reenabled after drain */ 125#define LK_NOPAUSE 0x01000000 /* no spinloop */ 126/* 127 * Internal lock flags. 128 * 129 * These flags are used internally to the lock manager. 130 */ 131#define LK_WANT_UPGRADE 0x00000100 /* waiting for share-to-excl upgrade */ 132#define LK_WANT_EXCL 0x00000200 /* exclusive lock sought */ 133#define LK_HAVE_EXCL 0x00000400 /* exclusive lock obtained */ 134#define LK_WAITDRAIN 0x00000800 /* process waiting for lock to drain */ 135#define LK_DRAINING 0x00004000 /* lock is being drained */ 136/* 137 * Control flags 138 * 139 * Non-persistent external flags. 140 */ 141#define LK_INTERLOCK 0x00010000 /* 142 * unlock passed mutex after getting 143 * lk_interlock 144 */ 145#define LK_RETRY 0x00020000 /* vn_lock: retry until locked */ 146#define LK_NOOBJ 0x00040000 /* vget: don't create object */ 147#define LK_THISLAYER 0x00080000 /* vn_lock: lock/unlock only current layer */ 148 149/* 150 * Internal state flags corresponding to lk_sharecount, and lk_waitcount 151 */ 152#define LK_SHARE_NONZERO 0x00100000 153#define LK_WAIT_NONZERO 0x00200000 154 155/* 156 * Lock return status. 157 * 158 * Successfully obtained locks return 0. Locks will always succeed 159 * unless one of the following is true: 160 * LK_FORCEUPGRADE is requested and some other process has already 161 * requested a lock upgrade (returns EBUSY). 162 * LK_WAIT is set and a sleep would be required (returns EBUSY). 163 * LK_SLEEPFAIL is set and a sleep was done (returns ENOLCK). 164 * PCATCH is set in lock priority and a signal arrives (returns 165 * either EINTR or ERESTART if system calls is to be restarted). 166 * Non-null lock timeout and timeout expires (returns EWOULDBLOCK). 167 * A failed lock attempt always returns a non-zero error value. No lock 168 * is held after an error return (in particular, a failed LK_UPGRADE 169 * or LK_FORCEUPGRADE will have released its shared access lock). 170 */ 171 172/* 173 * Indicator that no process holds exclusive lock 174 */ 175#define LK_KERNPROC ((pid_t) -2) 176#define LK_NOPROC ((pid_t) -1) 177 178#ifdef INVARIANTS 179#define LOCKMGR_ASSERT(lkp, what, p) do { \ 180 switch ((what)) { \ 181 case LK_SHARED: \ 182 if (lockstatus((lkp), (p)) == LK_SHARED) \ 183 break; \ 184 /* fall into exclusive */ \ 185 case LK_EXCLUSIVE: \ 186 if (lockstatus((lkp), (p)) != LK_EXCLUSIVE) \ 187 panic("lock %s %s not held at %s:%d", \ 188 (lkp)->lk_wmesg, #what, __FILE__, \ 189 __LINE__); \ 190 break; \ 191 default: \ 192 panic("unknown LOCKMGR_ASSERT at %s:%d", __FILE__, \ 193 __LINE__); \ 194 } \ 195} while (0) 196#else /* INVARIANTS */ 197#define LOCKMGR_ASSERT(lkp, p, what) 198#endif /* INVARIANTS */ 199 200void dumplockinfo(struct lock *lkp); 201struct proc; 202 203void lockinit __P((struct lock *, int prio, char *wmesg, int timo, 204 int flags)); 205void lockdestroy __P((struct lock *)); 206 207#ifdef DEBUG_LOCKS 208int debuglockmgr __P((struct lock *, u_int flags, 209 struct mtx *, struct proc *p, 210 const char *, 211 const char *, 212 int)); 213#define lockmgr(lockp, flags, slockp, proc) \ 214 debuglockmgr((lockp), (flags), (slockp), (proc), \ 215 "lockmgr", __FILE__, __LINE__) 216#else 217int lockmgr __P((struct lock *, u_int flags, 218 struct mtx *, struct proc *p)); 219#endif 220void lockmgr_printinfo __P((struct lock *)); 221int lockstatus __P((struct lock *, struct proc *)); 222int lockcount __P((struct lock *)); 223 224#ifdef SIMPLELOCK_DEBUG 225void _simple_unlock __P((struct simplelock *alp, const char *, int)); 226#define simple_unlock(alp) _simple_unlock(alp, __FILE__, __LINE__) 227int _simple_lock_try __P((struct simplelock *alp, const char *, int)); 228#define simple_lock_try(alp) _simple_lock_try(alp, __FILE__, __LINE__) 229void _simple_lock __P((struct simplelock *alp, const char *, int)); 230#define simple_lock(alp) _simple_lock(alp, __FILE__, __LINE__) 231void simple_lock_init __P((struct simplelock *alp)); 232#else /* !SIMPLELOCK_DEBUG */ 233#if MAXCPU == 1 /* no multiprocessor locking is necessary */ 234#define NULL_SIMPLELOCKS 235#define simple_lock_init(alp) 236#define simple_lock(alp) 237#define simple_lock_try(alp) (1) /* always succeeds */ 238#define simple_unlock(alp) 239#endif /* MAXCPU == 1 */ 240#endif /* !SIMPLELOCK_DEBUG */ 241 242#endif /* !_LOCK_H_ */ 243