/* * Copyright (c) 1995 * The Regents of the University of California. All rights reserved. * * This code contains ideas from software contributed to Berkeley by * Avadis Tevanian, Jr., Michael Wayne Young, and the Mach Operating * System project at Carnegie-Mellon University. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. All advertising materials mentioning features or use of this software * must display the following acknowledgement: * This product includes software developed by the University of * California, Berkeley and its contributors. * 4. Neither the name of the University nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. * * @(#)lock.h 8.12 (Berkeley) 5/19/95 * $FreeBSD: src/sys/sys/lock.h,v 1.13.2.1 1999/08/29 16:32:30 peter Exp $ */ #ifndef _LOCK_H_ #define _LOCK_H_ #include /* * The general lock structure. Provides for multiple shared locks, * upgrading from shared to exclusive, and sleeping until the lock * can be gained. The simple locks are defined in . */ struct lock { struct simplelock lk_interlock; /* lock on remaining fields */ u_int lk_flags; /* see below */ int lk_sharecount; /* # of accepted shared locks */ int lk_waitcount; /* # of processes sleeping for lock */ short lk_exclusivecount; /* # of recursive exclusive locks */ short lk_prio; /* priority at which to sleep */ char *lk_wmesg; /* resource sleeping (for tsleep) */ int lk_timo; /* maximum sleep time (for tsleep) */ pid_t lk_lockholder; /* pid of exclusive lock holder */ #ifdef DEBUG_LOCKS const char *lk_filename; const char *lk_lockername; int lk_lineno; #endif }; /* * Lock request types: * LK_SHARED - get one of many possible shared locks. If a process * holding an exclusive lock requests a shared lock, the exclusive * lock(s) will be downgraded to shared locks. * LK_EXCLUSIVE - stop further shared locks, when they are cleared, * grant a pending upgrade if it exists, then grant an exclusive * lock. Only one exclusive lock may exist at a time, except that * a process holding an exclusive lock may get additional exclusive * locks if it explicitly sets the LK_CANRECURSE flag in the lock * request, or if the LK_CANRECUSE flag was set when the lock was * initialized. * LK_UPGRADE - the process must hold a shared lock that it wants to * have upgraded to an exclusive lock. Other processes may get * exclusive access to the resource between the time that the upgrade * is requested and the time that it is granted. * LK_EXCLUPGRADE - the process must hold a shared lock that it wants to * have upgraded to an exclusive lock. If the request succeeds, no * other processes will have gotten exclusive access to the resource * between the time that the upgrade is requested and the time that * it is granted. However, if another process has already requested * an upgrade, the request will fail (see error returns below). * LK_DOWNGRADE - the process must hold an exclusive lock that it wants * to have downgraded to a shared lock. If the process holds multiple * (recursive) exclusive locks, they will all be downgraded to shared * locks. * LK_RELEASE - release one instance of a lock. * LK_DRAIN - wait for all activity on the lock to end, then mark it * decommissioned. This feature is used before freeing a lock that * is part of a piece of memory that is about to be freed. * * These are flags that are passed to the lockmgr routine. */ #define LK_TYPE_MASK 0x0000000f /* type of lock sought */ #define LK_SHARED 0x00000001 /* shared lock */ #define LK_EXCLUSIVE 0x00000002 /* exclusive lock */ #define LK_UPGRADE 0x00000003 /* shared-to-exclusive upgrade */ #define LK_EXCLUPGRADE 0x00000004 /* first shared-to-exclusive upgrade */ #define LK_DOWNGRADE 0x00000005 /* exclusive-to-shared downgrade */ #define LK_RELEASE 0x00000006 /* release any type of lock */ #define LK_DRAIN 0x00000007 /* wait for all lock activity to end */ /* * External lock flags. * * The first three flags may be set in lock_init to set their mode permanently, * or passed in as arguments to the lock manager. The LK_REENABLE flag may be * set only at the release of a lock obtained by drain. */ #define LK_EXTFLG_MASK 0x01000070 /* mask of external flags */ #define LK_NOWAIT 0x00000010 /* do not sleep to await lock */ #define LK_SLEEPFAIL 0x00000020 /* sleep, then return failure */ #define LK_CANRECURSE 0x00000040 /* allow recursive exclusive lock */ #define LK_REENABLE 0x00000080 /* lock is be reenabled after drain */ #define LK_NOPAUSE 0x01000000 /* no spinloop */ /* * Internal lock flags. * * These flags are used internally to the lock manager. */ #define LK_WANT_UPGRADE 0x00000100 /* waiting for share-to-excl upgrade */ #define LK_WANT_EXCL 0x00000200 /* exclusive lock sought */ #define LK_HAVE_EXCL 0x00000400 /* exclusive lock obtained */ #define LK_WAITDRAIN 0x00000800 /* process waiting for lock to drain */ #define LK_DRAINING 0x00004000 /* lock is being drained */ #define LK_DRAINED 0x00008000 /* lock has been decommissioned */ /* * Control flags * * Non-persistent external flags. */ #define LK_INTERLOCK 0x00010000 /* unlock passed simple lock after getting lk_interlock */ #define LK_RETRY 0x00020000 /* vn_lock: retry until locked */ #define LK_NOOBJ 0x00040000 /* vget: don't create object */ /* * Internal state flags corresponding to lk_sharecount, and lk_waitcount */ #define LK_SHARE_NONZERO 0x00100000 #define LK_WAIT_NONZERO 0x00200000 /* * Lock return status. * * Successfully obtained locks return 0. Locks will always succeed * unless one of the following is true: * LK_FORCEUPGRADE is requested and some other process has already * requested a lock upgrade (returns EBUSY). * LK_WAIT is set and a sleep would be required (returns EBUSY). * LK_SLEEPFAIL is set and a sleep was done (returns ENOLCK). * PCATCH is set in lock priority and a signal arrives (returns * either EINTR or ERESTART if system calls is to be restarted). * Non-null lock timeout and timeout expires (returns EWOULDBLOCK). * A failed lock attempt always returns a non-zero error value. No lock * is held after an error return (in particular, a failed LK_UPGRADE * or LK_FORCEUPGRADE will have released its shared access lock). */ /* * Indicator that no process holds exclusive lock */ #define LK_KERNPROC ((pid_t) -2) #define LK_NOPROC ((pid_t) -1) void dumplockinfo(struct lock *lkp); struct proc; void lockinit __P((struct lock *, int prio, char *wmesg, int timo, int flags)); #ifdef DEBUG_LOCKS int debuglockmgr __P((struct lock *, u_int flags, struct simplelock *, struct proc *p, const char *, const char *, int)); #define lockmgr(lockp, flags, slockp, proc) \ debuglockmgr((lockp), (flags), (slockp), (proc), \ "lockmgr", __FILE__, __LINE__) #else int lockmgr __P((struct lock *, u_int flags, struct simplelock *, struct proc *p)); #endif void lockmgr_printinfo __P((struct lock *)); int lockstatus __P((struct lock *)); #ifdef SIMPLELOCK_DEBUG void _simple_unlock __P((struct simplelock *alp, const char *, int)); #define simple_unlock(alp) _simple_unlock(alp, __FILE__, __LINE__) int _simple_lock_try __P((struct simplelock *alp, const char *, int)); #define simple_lock_try(alp) _simple_lock_try(alp, __FILE__, __LINE__) void _simple_lock __P((struct simplelock *alp, const char *, int)); #define simple_lock(alp) _simple_lock(alp, __FILE__, __LINE__) void simple_lock_init __P((struct simplelock *alp)); #else /* !SIMPLELOCK_DEBUG */ #if NCPUS == 1 /* no multiprocessor locking is necessary */ #define NULL_SIMPLELOCKS #define simple_lock_init(alp) #define simple_lock(alp) #define simple_lock_try(alp) (1) /* always succeeds */ #define simple_unlock(alp) #endif /* NCPUS == 1 */ #endif /* !SIMPLELOCK_DEBUG */ #endif /* !_LOCK_H_ */