2 * Copyright (c) 2000-2005 Apple Computer, Inc. All rights reserved.
4 * @APPLE_LICENSE_OSREFERENCE_HEADER_START@
6 * This file contains Original Code and/or Modifications of Original Code
7 * as defined in and that are subject to the Apple Public Source License
8 * Version 2.0 (the 'License'). You may not use this file except in
9 * compliance with the License. The rights granted to you under the
10 * License may not be used to create, or enable the creation or
11 * redistribution of, unlawful or unlicensed copies of an Apple operating
12 * system, or to circumvent, violate, or enable the circumvention or
13 * violation of, any terms of an Apple operating system software license
16 * Please obtain a copy of the License at
17 * http://www.opensource.apple.com/apsl/ and read it before using this
20 * The Original Code and all software distributed under the License are
21 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
22 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
23 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
24 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
25 * Please see the License for the specific language governing rights and
26 * limitations under the License.
28 * @APPLE_LICENSE_OSREFERENCE_HEADER_END@
30 /* Copyright (c) 1995, 1997 Apple Computer, Inc. All Rights Reserved */
33 * The Regents of the University of California. All rights reserved.
35 * This code contains ideas from software contributed to Berkeley by
36 * Avadis Tevanian, Jr., Michael Wayne Young, and the Mach Operating
37 * System project at Carnegie-Mellon University.
39 * Redistribution and use in source and binary forms, with or without
40 * modification, are permitted provided that the following conditions
42 * 1. Redistributions of source code must retain the above copyright
43 * notice, this list of conditions and the following disclaimer.
44 * 2. Redistributions in binary form must reproduce the above copyright
45 * notice, this list of conditions and the following disclaimer in the
46 * documentation and/or other materials provided with the distribution.
47 * 3. All advertising materials mentioning features or use of this software
48 * must display the following acknowledgement:
49 * This product includes software developed by the University of
50 * California, Berkeley and its contributors.
51 * 4. Neither the name of the University nor the names of its contributors
52 * may be used to endorse or promote products derived from this software
53 * without specific prior written permission.
55 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
56 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
57 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
58 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
59 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
60 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
61 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
62 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
63 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
64 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
67 * @(#)lock.h 8.12 (Berkeley) 5/19/95
73 #include <sys/appleapiopts.h>
74 #include <sys/types.h>
75 #include <sys/cdefs.h>
79 #include <kern/locks.h>
83 #ifdef BSD_KERNEL_PRIVATE
85 * The general lock structure. Provides for multiple shared locks,
86 * upgrading from shared to exclusive, and sleeping until the lock
87 * can be gained. The simple locks are defined in <machine/param.h>.
90 void * lk_interlock
[10]; /* lock on remaining fields */
91 u_int lk_flags
; /* see below */
92 int lk_sharecount
; /* # of accepted shared locks */
93 int lk_waitcount
; /* # of processes sleeping for lock */
94 short lk_exclusivecount
; /* # of recursive exclusive locks */
95 short lk_prio
; /* priority at which to sleep */
96 const char *lk_wmesg
; /* resource sleeping (for tsleep) */
97 int lk_timo
; /* maximum sleep time (for tsleep) */
98 pid_t lk_lockholder
; /* pid of exclusive lock holder */
99 void *lk_lockthread
; /* thread which acquired excl lock */
102 // LP64todo - should this move?
104 /* LP64 version of lock__bsd__. all pointers
105 * grow when we're dealing with a 64-bit process.
106 * WARNING - keep in sync with lock__bsd__
109 struct user_lock__bsd__
{
110 user_addr_t lk_interlock
[10]; /* lock on remaining fields */
111 u_int lk_flags
; /* see below */
112 int lk_sharecount
; /* # of accepted shared locks */
113 int lk_waitcount
; /* # of processes sleeping for lock */
114 short lk_exclusivecount
; /* # of recursive exclusive locks */
115 short lk_prio
; /* priority at which to sleep */
116 user_addr_t lk_wmesg
; /* resource sleeping (for tsleep) */
117 int lk_timo
; /* maximum sleep time (for tsleep) */
118 pid_t lk_lockholder
; /* pid of exclusive lock holder */
119 user_addr_t lk_lockthread
; /* thread which acquired excl lock */
123 * Lock request types:
124 * LK_SHARED - get one of many possible shared locks. If a process
125 * holding an exclusive lock requests a shared lock, the exclusive
126 * lock(s) will be downgraded to shared locks.
127 * LK_EXCLUSIVE - stop further shared locks, when they are cleared,
128 * grant a pending upgrade if it exists, then grant an exclusive
129 * lock. Only one exclusive lock may exist at a time, except that
130 * a process holding an exclusive lock may get additional exclusive
131 * locks if it explicitly sets the LK_CANRECURSE flag in the lock
132 * request, or if the LK_CANRECUSE flag was set when the lock was
134 * LK_UPGRADE - the process must hold a shared lock that it wants to
135 * have upgraded to an exclusive lock. Other processes may get
136 * exclusive access to the resource between the time that the upgrade
137 * is requested and the time that it is granted.
138 * LK_EXCLUPGRADE - the process must hold a shared lock that it wants to
139 * have upgraded to an exclusive lock. If the request succeeds, no
140 * other processes will have gotten exclusive access to the resource
141 * between the time that the upgrade is requested and the time that
142 * it is granted. However, if another process has already requested
143 * an upgrade, the request will fail (see error returns below).
144 * LK_DOWNGRADE - the process must hold an exclusive lock that it wants
145 * to have downgraded to a shared lock. If the process holds multiple
146 * (recursive) exclusive locks, they will all be downgraded to shared
148 * LK_RELEASE - release one instance of a lock.
149 * LK_DRAIN - wait for all activity on the lock to end, then mark it
150 * decommissioned. This feature is used before freeing a lock that
151 * is part of a piece of memory that is about to be freed.
153 * These are flags that are passed to the lockmgr routine.
155 #define LK_TYPE_MASK 0x0000000f /* type of lock sought */
156 #define LK_SHARED 0x00000001 /* shared lock */
157 #define LK_EXCLUSIVE 0x00000002 /* exclusive lock */
158 #define LK_UPGRADE 0x00000003 /* shared-to-exclusive upgrade */
159 #define LK_EXCLUPGRADE 0x00000004 /* first shared-to-exclusive upgrade */
160 #define LK_DOWNGRADE 0x00000005 /* exclusive-to-shared downgrade */
161 #define LK_RELEASE 0x00000006 /* release any type of lock */
162 #define LK_DRAIN 0x00000007 /* wait for all lock activity to end */
164 * External lock flags.
166 * The first three flags may be set in lock_init to set their mode permanently,
167 * or passed in as arguments to the lock manager. The LK_REENABLE flag may be
168 * set only at the release of a lock obtained by drain.
170 #define LK_EXTFLG_MASK 0x00000070 /* mask of external flags */
171 #define LK_NOWAIT 0x00000010 /* do not sleep to await lock */
172 #define LK_SLEEPFAIL 0x00000020 /* sleep, then return failure */
173 #define LK_CANRECURSE 0x00000040 /* allow recursive exclusive lock */
174 #define LK_REENABLE 0x00000080 /* lock is be reenabled after drain */
176 * Internal lock flags.
178 * These flags are used internally to the lock manager.
180 #define LK_WANT_UPGRADE 0x00000100 /* waiting for share-to-excl upgrade */
181 #define LK_WANT_EXCL 0x00000200 /* exclusive lock sought */
182 #define LK_HAVE_EXCL 0x00000400 /* exclusive lock obtained */
183 #define LK_WAITDRAIN 0x00000800 /* process waiting for lock to drain */
184 #define LK_DRAINING 0x00004000 /* lock is being drained */
185 #define LK_DRAINED 0x00008000 /* lock has been decommissioned */
189 * Non-persistent external flags.
191 #define LK_INTERLOCK 0x00010000 /* unlock passed simple lock after
192 getting lk_interlock */
193 #define LK_RETRY 0x00020000 /* vn_lock: retry until locked */
196 * Lock return status.
198 * Successfully obtained locks return 0. Locks will always succeed
199 * unless one of the following is true:
200 * LK_FORCEUPGRADE is requested and some other process has already
201 * requested a lock upgrade (returns EBUSY).
202 * LK_WAIT is set and a sleep would be required (returns EBUSY).
203 * LK_SLEEPFAIL is set and a sleep was done (returns ENOLCK).
204 * PCATCH is set in lock priority and a signal arrives (returns
205 * either EINTR or ERESTART if system calls is to be restarted).
206 * Non-null lock timeout and timeout expires (returns EWOULDBLOCK).
207 * A failed lock attempt always returns a non-zero error value. No lock
208 * is held after an error return (in particular, a failed LK_UPGRADE
209 * or LK_FORCEUPGRADE will have released its shared access lock).
213 * Indicator that no process holds exclusive lock
215 #define LK_KERNPROC ((pid_t) -2)
216 #define LK_NOPROC ((pid_t) -1)
220 void lockinit(struct lock__bsd__
*, int prio
, const char *wmesg
, int timo
,
222 int lockmgr(struct lock__bsd__
*, u_int flags
,
223 void *, struct proc
*p
);
224 int lockstatus(struct lock__bsd__
*);
226 #endif /* BSD_KERNEL_PRIVATE */
228 #endif /* _SYS_LOCK_H_ */