Annotation of sys/sys/lock.h, Revision 1.1
1.1 ! nbrk 1: /* $OpenBSD: lock.h,v 1.18 2007/04/12 22:20:14 thib Exp $ */
! 2:
! 3: /*
! 4: * Copyright (c) 1995
! 5: * The Regents of the University of California. All rights reserved.
! 6: *
! 7: * This code contains ideas from software contributed to Berkeley by
! 8: * Avadis Tevanian, Jr., Michael Wayne Young, and the Mach Operating
! 9: * System project at Carnegie-Mellon University.
! 10: *
! 11: * Redistribution and use in source and binary forms, with or without
! 12: * modification, are permitted provided that the following conditions
! 13: * are met:
! 14: * 1. Redistributions of source code must retain the above copyright
! 15: * notice, this list of conditions and the following disclaimer.
! 16: * 2. Redistributions in binary form must reproduce the above copyright
! 17: * notice, this list of conditions and the following disclaimer in the
! 18: * documentation and/or other materials provided with the distribution.
! 19: * 3. Neither the name of the University nor the names of its contributors
! 20: * may be used to endorse or promote products derived from this software
! 21: * without specific prior written permission.
! 22: *
! 23: * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
! 24: * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
! 25: * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
! 26: * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
! 27: * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
! 28: * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
! 29: * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
! 30: * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
! 31: * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
! 32: * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
! 33: * SUCH DAMAGE.
! 34: *
! 35: * @(#)lock.h 8.12 (Berkeley) 5/19/95
! 36: */
! 37:
! 38: #ifndef _LOCK_H_
! 39: #define _LOCK_H_
! 40:
! 41: #include <sys/simplelock.h>
! 42:
! 43: typedef struct simplelock simple_lock_data_t;
! 44: typedef struct simplelock *simple_lock_t;
! 45: typedef struct lock lock_data_t;
! 46: typedef struct lock *lock_t;
! 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: */
! 53: struct lock {
! 54: u_int lk_flags; /* see below */
! 55: int lk_sharecount; /* # of accepted shared locks */
! 56: int lk_waitcount; /* # of processes sleeping for lock */
! 57: int lk_exclusivecount; /* # of recursive exclusive locks */
! 58:
! 59: /*
! 60: * This is the sleep message for sleep locks, and a simple name
! 61: * for spin locks.
! 62: */
! 63: char *lk_wmesg; /* resource sleeping (for tsleep) */
! 64:
! 65: /* pid of exclusive lock holder */
! 66: pid_t lk_lockholder;
! 67:
! 68: /* priority at which to sleep */
! 69: int lk_prio;
! 70:
! 71: /* maximum sleep time (for tsleep) */
! 72: int lk_timo;
! 73:
! 74: #if defined(LOCKDEBUG)
! 75: const char *lk_lock_file;
! 76: const char *lk_unlock_file;
! 77: int lk_lock_line;
! 78: int lk_unlock_line;
! 79: #endif
! 80: };
! 81:
! 82: /*
! 83: * Lock request types:
! 84: * LK_SHARED - get one of many possible shared locks. If a process
! 85: * holding an exclusive lock requests a shared lock, the exclusive
! 86: * lock(s) will be downgraded to shared locks.
! 87: * LK_EXCLUSIVE - stop further shared locks, when they are cleared,
! 88: * grant a pending upgrade if it exists, then grant an exclusive
! 89: * lock. Only one exclusive lock may exist at a time, except that
! 90: * a process holding an exclusive lock may get additional exclusive
! 91: * locks if it explicitly sets the LK_CANRECURSE flag in the lock
! 92: * request, or if the LK_CANRECUSE flag was set when the lock was
! 93: * initialized.
! 94: * LK_RELEASE - release one instance of a lock.
! 95: * LK_DRAIN - wait for all activity on the lock to end, then mark it
! 96: * decommissioned. This feature is used before freeing a lock that
! 97: * is part of a piece of memory that is about to be freed.
! 98: *
! 99: * These are flags that are passed to the lockmgr routine.
! 100: */
! 101: #define LK_TYPE_MASK 0x0000000f /* type of lock sought */
! 102: #define LK_SHARED 0x00000001 /* shared lock */
! 103: #define LK_EXCLUSIVE 0x00000002 /* exclusive lock */
! 104: #define LK_RELEASE 0x00000006 /* release any type of lock */
! 105: #define LK_DRAIN 0x00000007 /* wait for all lock activity to end */
! 106: /*
! 107: * External lock flags.
! 108: *
! 109: * The first three flags may be set in lock_init to set their mode permanently,
! 110: * or passed in as arguments to the lock manager.
! 111: */
! 112: #define LK_EXTFLG_MASK 0x00200070 /* mask of external flags */
! 113: #define LK_NOWAIT 0x00000010 /* do not sleep to await lock */
! 114: #define LK_SLEEPFAIL 0x00000020 /* sleep, then return failure */
! 115: #define LK_CANRECURSE 0x00000040 /* allow recursive exclusive lock */
! 116: #define LK_RECURSEFAIL 0x00200000 /* fail if recursive exclusive lock */
! 117: /*
! 118: * Internal lock flags.
! 119: *
! 120: * These flags are used internally to the lock manager.
! 121: */
! 122: #define LK_WANT_EXCL 0x00002000 /* exclusive lock sought */
! 123: #define LK_HAVE_EXCL 0x00004000 /* exclusive lock obtained */
! 124: #define LK_WAITDRAIN 0x00008000 /* process waiting for lock to drain */
! 125: #define LK_DRAINING 0x00040000 /* lock is being drained */
! 126: #define LK_DRAINED 0x00080000 /* lock has been decommissioned */
! 127: /*
! 128: * Control flags
! 129: *
! 130: * Non-persistent external flags.
! 131: */
! 132: #define LK_RETRY 0x00020000 /* vn_lock: retry until locked */
! 133:
! 134: /*
! 135: * Lock return status.
! 136: *
! 137: * Successfully obtained locks return 0. Locks will always succeed
! 138: * unless one of the following is true:
! 139: * LK_NOWAIT is set and a sleep would be required (returns EBUSY).
! 140: * LK_SLEEPFAIL is set and a sleep was done (returns ENOLCK).
! 141: * PCATCH is set in lock priority and a signal arrives (returns
! 142: * either EINTR or ERESTART if system calls is to be restarted).
! 143: * Non-null lock timeout and timeout expires (returns EWOULDBLOCK).
! 144: * A failed lock attempt always returns a non-zero error value. No lock
! 145: * is held after an error return.
! 146: */
! 147:
! 148: /*
! 149: * Indicator that no process holds exclusive lock
! 150: */
! 151: #define LK_KERNPROC ((pid_t) -2)
! 152: #define LK_NOPROC ((pid_t) -1)
! 153: #define LK_NOCPU ((cpuid_t) -1)
! 154:
! 155: struct proc;
! 156:
! 157: void lockinit(struct lock *, int prio, char *wmesg, int timo,
! 158: int flags);
! 159: int lockmgr(__volatile struct lock *, u_int flags, struct simplelock *);
! 160: void lockmgr_printinfo(__volatile struct lock *);
! 161: int lockstatus(struct lock *);
! 162:
! 163: #if defined(LOCKDEBUG)
! 164: int _spinlock_release_all(__volatile struct lock *, const char *, int);
! 165: void _spinlock_acquire_count(__volatile struct lock *, int, const char *,
! 166: int);
! 167:
! 168: #define spinlock_release_all(l) _spinlock_release_all((l), __FILE__, __LINE__)
! 169: #define spinlock_acquire_count(l, c) _spinlock_acquire_count((l), (c), \
! 170: __FILE__, __LINE__)
! 171: #else
! 172: int spinlock_release_all(__volatile struct lock *);
! 173: void spinlock_acquire_count(__volatile struct lock *, int);
! 174: #endif
! 175:
! 176: #ifdef LOCKDEBUG
! 177: #define LOCK_ASSERT(x) KASSERT(x)
! 178: #else
! 179: #define LOCK_ASSERT(x) /* nothing */
! 180: #endif
! 181:
! 182: #if !defined(MULTIPROCESSOR)
! 183: /*
! 184: * XXX Simplelock macros used at "trusted" places.
! 185: */
! 186: #define SIMPLELOCK simplelock
! 187: #define SIMPLE_LOCK_INIT simple_lock_init
! 188: #define SIMPLE_LOCK simple_lock
! 189: #define SIMPLE_UNLOCK simple_unlock
! 190: #endif
! 191:
! 192: #endif /* !_LOCK_H_ */
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