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_ */