Annotation of sys/sys/lock.h, Revision 1.1.1.1
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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