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1.1 root 1: /*
2: * Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
3: *
4: * @APPLE_LICENSE_HEADER_START@
5: *
6: * The contents of this file constitute Original Code as defined in and
7: * are subject to the Apple Public Source License Version 1.1 (the
8: * "License"). You may not use this file except in compliance with the
9: * License. Please obtain a copy of the License at
10: * http://www.apple.com/publicsource and read it before using this file.
11: *
12: * This Original Code and all software distributed under the License are
13: * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
14: * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
15: * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
16: * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT. Please see the
17: * License for the specific language governing rights and limitations
18: * under the License.
19: *
20: * @APPLE_LICENSE_HEADER_END@
21: */
22: /* Copyright (c) 1995, 1997 Apple Computer, Inc. All Rights Reserved */
23: /*
24: * Copyright (c) 1995
25: * The Regents of the University of California. All rights reserved.
26: *
27: * This code contains ideas from software contributed to Berkeley by
28: * Avadis Tevanian, Jr., Michael Wayne Young, and the Mach Operating
29: * System project at Carnegie-Mellon University.
30: *
31: * Redistribution and use in source and binary forms, with or without
32: * modification, are permitted provided that the following conditions
33: * are met:
34: * 1. Redistributions of source code must retain the above copyright
35: * notice, this list of conditions and the following disclaimer.
36: * 2. Redistributions in binary form must reproduce the above copyright
37: * notice, this list of conditions and the following disclaimer in the
38: * documentation and/or other materials provided with the distribution.
39: * 3. All advertising materials mentioning features or use of this software
40: * must display the following acknowledgement:
41: * This product includes software developed by the University of
42: * California, Berkeley and its contributors.
43: * 4. Neither the name of the University nor the names of its contributors
44: * may be used to endorse or promote products derived from this software
45: * without specific prior written permission.
46: *
47: * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
48: * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
49: * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
50: * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
51: * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
52: * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
53: * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
54: * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
55: * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
56: * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
57: * SUCH DAMAGE.
58: *
59: * @(#)lock.h 8.12 (Berkeley) 5/19/95
60: */
61:
62: #ifndef _SYS_LOCK_H_
63: #define _SYS_LOCK_H_
64: #ifdef KERNEL
65:
66: #include <kern/simple_lock.h>
67: #include <kern/simple_lock_types.h>
68:
69: #if defined(simple_lock_init)
70: #undef simple_lock_init
71: #endif
72: #define simple_lock_init(l) usimple_lock_init((l),0)
73:
74: #else /* KERNEL */
75:
76: #ifndef _MACHINE_SIMPLE_LOCK_DATA_
77: #define _MACHINE_SIMPLE_LOCK_DATA_
78:
79: #include <mach/boolean.h>
80:
81: #if defined(__ppc__)
82: struct slock{
83: volatile unsigned int lock_data[10];
84: };
85: #else
86: struct slock{
87: volatile unsigned int lock_data[9];
88: };
89: #endif
90: typedef struct slock simple_lock_data_t;
91: typedef struct slock *simple_lock_t;
92: #define decl_simple_lock_data(class,name) \
93: class simple_lock_data_t name;
94:
95: #endif /* _MACHINE_SIMPLE_LOCK_DATA_ */
96:
97: #endif /* KERNEL */
98: /*
99: * The general lock structure. Provides for multiple shared locks,
100: * upgrading from shared to exclusive, and sleeping until the lock
101: * can be gained. The simple locks are defined in <machine/param.h>.
102: */
103: struct lock__bsd__ {
104: simple_lock_data_t
105: lk_interlock; /* lock on remaining fields */
106: u_int lk_flags; /* see below */
107: int lk_sharecount; /* # of accepted shared locks */
108: int lk_waitcount; /* # of processes sleeping for lock */
109: short lk_exclusivecount; /* # of recursive exclusive locks */
110: short lk_prio; /* priority at which to sleep */
111: char *lk_wmesg; /* resource sleeping (for tsleep) */
112: int lk_timo; /* maximum sleep time (for tsleep) */
113: pid_t lk_lockholder; /* pid of exclusive lock holder */
114: void *lk_lockthread; /* thread which acquired excl lock */
115: };
116: /*
117: * Lock request types:
118: * LK_SHARED - get one of many possible shared locks. If a process
119: * holding an exclusive lock requests a shared lock, the exclusive
120: * lock(s) will be downgraded to shared locks.
121: * LK_EXCLUSIVE - stop further shared locks, when they are cleared,
122: * grant a pending upgrade if it exists, then grant an exclusive
123: * lock. Only one exclusive lock may exist at a time, except that
124: * a process holding an exclusive lock may get additional exclusive
125: * locks if it explicitly sets the LK_CANRECURSE flag in the lock
126: * request, or if the LK_CANRECUSE flag was set when the lock was
127: * initialized.
128: * LK_UPGRADE - the process must hold a shared lock that it wants to
129: * have upgraded to an exclusive lock. Other processes may get
130: * exclusive access to the resource between the time that the upgrade
131: * is requested and the time that it is granted.
132: * LK_EXCLUPGRADE - the process must hold a shared lock that it wants to
133: * have upgraded to an exclusive lock. If the request succeeds, no
134: * other processes will have gotten exclusive access to the resource
135: * between the time that the upgrade is requested and the time that
136: * it is granted. However, if another process has already requested
137: * an upgrade, the request will fail (see error returns below).
138: * LK_DOWNGRADE - the process must hold an exclusive lock that it wants
139: * to have downgraded to a shared lock. If the process holds multiple
140: * (recursive) exclusive locks, they will all be downgraded to shared
141: * locks.
142: * LK_RELEASE - release one instance of a lock.
143: * LK_DRAIN - wait for all activity on the lock to end, then mark it
144: * decommissioned. This feature is used before freeing a lock that
145: * is part of a piece of memory that is about to be freed.
146: *
147: * These are flags that are passed to the lockmgr routine.
148: */
149: #define LK_TYPE_MASK 0x0000000f /* type of lock sought */
150: #define LK_SHARED 0x00000001 /* shared lock */
151: #define LK_EXCLUSIVE 0x00000002 /* exclusive lock */
152: #define LK_UPGRADE 0x00000003 /* shared-to-exclusive upgrade */
153: #define LK_EXCLUPGRADE 0x00000004 /* first shared-to-exclusive upgrade */
154: #define LK_DOWNGRADE 0x00000005 /* exclusive-to-shared downgrade */
155: #define LK_RELEASE 0x00000006 /* release any type of lock */
156: #define LK_DRAIN 0x00000007 /* wait for all lock activity to end */
157: /*
158: * External lock flags.
159: *
160: * The first three flags may be set in lock_init to set their mode permanently,
161: * or passed in as arguments to the lock manager. The LK_REENABLE flag may be
162: * set only at the release of a lock obtained by drain.
163: */
164: #define LK_EXTFLG_MASK 0x00000070 /* mask of external flags */
165: #define LK_NOWAIT 0x00000010 /* do not sleep to await lock */
166: #define LK_SLEEPFAIL 0x00000020 /* sleep, then return failure */
167: #define LK_CANRECURSE 0x00000040 /* allow recursive exclusive lock */
168: #define LK_REENABLE 0x00000080 /* lock is be reenabled after drain */
169: /*
170: * Internal lock flags.
171: *
172: * These flags are used internally to the lock manager.
173: */
174: #define LK_WANT_UPGRADE 0x00000100 /* waiting for share-to-excl upgrade */
175: #define LK_WANT_EXCL 0x00000200 /* exclusive lock sought */
176: #define LK_HAVE_EXCL 0x00000400 /* exclusive lock obtained */
177: #define LK_WAITDRAIN 0x00000800 /* process waiting for lock to drain */
178: #define LK_DRAINING 0x00004000 /* lock is being drained */
179: #define LK_DRAINED 0x00008000 /* lock has been decommissioned */
180: /*
181: * Control flags
182: *
183: * Non-persistent external flags.
184: */
185: #define LK_INTERLOCK 0x00010000 /* unlock passed simple lock after
186: getting lk_interlock */
187: #define LK_RETRY 0x00020000 /* vn_lock: retry until locked */
188:
189: /*
190: * Lock return status.
191: *
192: * Successfully obtained locks return 0. Locks will always succeed
193: * unless one of the following is true:
194: * LK_FORCEUPGRADE is requested and some other process has already
195: * requested a lock upgrade (returns EBUSY).
196: * LK_WAIT is set and a sleep would be required (returns EBUSY).
197: * LK_SLEEPFAIL is set and a sleep was done (returns ENOLCK).
198: * PCATCH is set in lock priority and a signal arrives (returns
199: * either EINTR or ERESTART if system calls is to be restarted).
200: * Non-null lock timeout and timeout expires (returns EWOULDBLOCK).
201: * A failed lock attempt always returns a non-zero error value. No lock
202: * is held after an error return (in particular, a failed LK_UPGRADE
203: * or LK_FORCEUPGRADE will have released its shared access lock).
204: */
205:
206: /*
207: * Indicator that no process holds exclusive lock
208: */
209: #define LK_KERNPROC ((pid_t) -2)
210: #define LK_NOPROC ((pid_t) -1)
211:
212: struct proc;
213:
214: void lockinit __P((struct lock__bsd__ *, int prio, char *wmesg, int timo,
215: int flags));
216: int lockmgr __P((struct lock__bsd__ *, u_int flags,
217: simple_lock_t, struct proc *p));
218: int lockstatus __P((struct lock__bsd__ *));
219:
220: #endif /* _SYS_LOCK_H_ */
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