proc->thread stage 4: rework the VFS and DEVICE subsystems to take thread
[dragonfly.git] / sys / sys / lock.h
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1/*
2 * Copyright (c) 1995
3 * The Regents of the University of California. All rights reserved.
4 *
5 * This code contains ideas from software contributed to Berkeley by
6 * Avadis Tevanian, Jr., Michael Wayne Young, and the Mach Operating
7 * System project at Carnegie-Mellon University.
8 *
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
11 * are met:
12 * 1. Redistributions of source code must retain the above copyright
13 * notice, this list of conditions and the following disclaimer.
14 * 2. Redistributions in binary form must reproduce the above copyright
15 * notice, this list of conditions and the following disclaimer in the
16 * documentation and/or other materials provided with the distribution.
17 * 3. All advertising materials mentioning features or use of this software
18 * must display the following acknowledgement:
19 * This product includes software developed by the University of
20 * California, Berkeley and its contributors.
21 * 4. Neither the name of the University nor the names of its contributors
22 * may be used to endorse or promote products derived from this software
23 * without specific prior written permission.
24 *
25 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
26 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
27 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
28 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
29 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
30 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
31 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
32 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
33 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
34 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
35 * SUCH DAMAGE.
36 *
37 * @(#)lock.h 8.12 (Berkeley) 5/19/95
38 * $FreeBSD: src/sys/sys/lock.h,v 1.17.2.3 2001/12/25 01:44:44 dillon Exp $
dadab5e9 39 * $DragonFly: src/sys/sys/lock.h,v 1.3 2003/06/25 03:56:10 dillon Exp $
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40 */
41
42#ifndef _LOCK_H_
43#define _LOCK_H_
44
45
46#include <machine/lock.h>
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 */
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53struct thread;
54
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55struct lock {
56 struct simplelock lk_interlock; /* lock on remaining fields */
57 u_int lk_flags; /* see below */
58 int lk_sharecount; /* # of accepted shared locks */
59 int lk_waitcount; /* # of processes sleeping for lock */
60 short lk_exclusivecount; /* # of recursive exclusive locks */
61 short lk_prio; /* priority at which to sleep */
62 char *lk_wmesg; /* resource sleeping (for tsleep) */
63 int lk_timo; /* maximum sleep time (for tsleep) */
dadab5e9 64 struct thread *lk_lockholder; /* thread of excl lock holder */
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65#ifdef DEBUG_LOCKS
66 const char *lk_filename;
67 const char *lk_lockername;
68 int lk_lineno;
69#endif
70};
71/*
72 * Lock request types:
73 * LK_SHARED - get one of many possible shared locks. If a process
74 * holding an exclusive lock requests a shared lock, the exclusive
75 * lock(s) will be downgraded to shared locks.
76 * LK_EXCLUSIVE - stop further shared locks, when they are cleared,
77 * grant a pending upgrade if it exists, then grant an exclusive
78 * lock. Only one exclusive lock may exist at a time, except that
79 * a process holding an exclusive lock may get additional exclusive
80 * locks if it explicitly sets the LK_CANRECURSE flag in the lock
81 * request, or if the LK_CANRECUSE flag was set when the lock was
82 * initialized.
83 * LK_UPGRADE - the process must hold a shared lock that it wants to
84 * have upgraded to an exclusive lock. Other processes may get
85 * exclusive access to the resource between the time that the upgrade
86 * is requested and the time that it is granted.
87 * LK_EXCLUPGRADE - the process must hold a shared lock that it wants to
88 * have upgraded to an exclusive lock. If the request succeeds, no
89 * other processes will have gotten exclusive access to the resource
90 * between the time that the upgrade is requested and the time that
91 * it is granted. However, if another process has already requested
92 * an upgrade, the request will fail (see error returns below).
93 * LK_DOWNGRADE - the process must hold an exclusive lock that it wants
94 * to have downgraded to a shared lock. If the process holds multiple
95 * (recursive) exclusive locks, they will all be downgraded to shared
96 * locks.
97 * LK_RELEASE - release one instance of a lock.
98 * LK_DRAIN - wait for all activity on the lock to end, then mark it
99 * decommissioned. This feature is used before freeing a lock that
100 * is part of a piece of memory that is about to be freed.
101 * LK_EXCLOTHER - return for lockstatus(). Used when another process
102 * holds the lock exclusively.
103 *
104 * These are flags that are passed to the lockmgr routine.
105 */
106#define LK_TYPE_MASK 0x0000000f /* type of lock sought */
107#define LK_SHARED 0x00000001 /* shared lock */
108#define LK_EXCLUSIVE 0x00000002 /* exclusive lock */
109#define LK_UPGRADE 0x00000003 /* shared-to-exclusive upgrade */
110#define LK_EXCLUPGRADE 0x00000004 /* first shared-to-exclusive upgrade */
111#define LK_DOWNGRADE 0x00000005 /* exclusive-to-shared downgrade */
112#define LK_RELEASE 0x00000006 /* release any type of lock */
113#define LK_DRAIN 0x00000007 /* wait for all lock activity to end */
114#define LK_EXCLOTHER 0x00000008 /* other process holds lock */
115/*
116 * External lock flags.
117 *
118 * The first three flags may be set in lock_init to set their mode permanently,
119 * or passed in as arguments to the lock manager. The LK_REENABLE flag may be
120 * set only at the release of a lock obtained by drain.
121 */
122#define LK_EXTFLG_MASK 0x03000070 /* mask of external flags */
123#define LK_NOWAIT 0x00000010 /* do not sleep to await lock */
124#define LK_SLEEPFAIL 0x00000020 /* sleep, then return failure */
125#define LK_CANRECURSE 0x00000040 /* allow recursive exclusive lock */
126#define LK_REENABLE 0x00000080 /* lock is be reenabled after drain */
127#define LK_NOPAUSE 0x01000000 /* no spinloop */
128#define LK_TIMELOCK 0x02000000
129/*
130 * Internal lock flags.
131 *
132 * These flags are used internally to the lock manager.
133 */
134#define LK_WANT_UPGRADE 0x00000100 /* waiting for share-to-excl upgrade */
135#define LK_WANT_EXCL 0x00000200 /* exclusive lock sought */
136#define LK_HAVE_EXCL 0x00000400 /* exclusive lock obtained */
137#define LK_WAITDRAIN 0x00000800 /* process waiting for lock to drain */
138#define LK_DRAINING 0x00004000 /* lock is being drained */
139/*
140 * Control flags
141 *
142 * Non-persistent external flags.
143 */
144#define LK_INTERLOCK 0x00010000 /* unlock passed simple lock after
145 getting lk_interlock */
146#define LK_RETRY 0x00020000 /* vn_lock: retry until locked */
147#define LK_NOOBJ 0x00040000 /* vget: don't create object */
148#define LK_THISLAYER 0x00080000 /* vn_lock: lock/unlock only current layer */
149
150/*
151 * Internal state flags corresponding to lk_sharecount, and lk_waitcount
152 */
153#define LK_SHARE_NONZERO 0x00100000
154#define LK_WAIT_NONZERO 0x00200000
155
156/*
157 * Lock return status.
158 *
159 * Successfully obtained locks return 0. Locks will always succeed
160 * unless one of the following is true:
161 * LK_FORCEUPGRADE is requested and some other process has already
162 * requested a lock upgrade (returns EBUSY).
163 * LK_WAIT is set and a sleep would be required (returns EBUSY).
164 * LK_SLEEPFAIL is set and a sleep was done (returns ENOLCK).
165 * PCATCH is set in lock priority and a signal arrives (returns
166 * either EINTR or ERESTART if system calls is to be restarted).
167 * Non-null lock timeout and timeout expires (returns EWOULDBLOCK).
168 * A failed lock attempt always returns a non-zero error value. No lock
169 * is held after an error return (in particular, a failed LK_UPGRADE
170 * or LK_FORCEUPGRADE will have released its shared access lock).
171 */
172
173/*
174 * Indicator that no process holds exclusive lock
175 */
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176#define LK_KERNTHREAD ((struct thread *)-2)
177#define LK_NOTHREAD ((struct thread *)-1)
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178
179void dumplockinfo(struct lock *lkp);
180struct proc;
181
182void lockinit __P((struct lock *, int prio, char *wmesg, int timo,
183 int flags));
184#ifdef DEBUG_LOCKS
185int debuglockmgr __P((struct lock *, u_int flags,
dadab5e9 186 struct simplelock *, struct thread *p,
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187 const char *,
188 const char *,
189 int));
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190#define lockmgr(lockp, flags, slockp, td) \
191 debuglockmgr((lockp), (flags), (slockp), (td), \
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192 "lockmgr", __FILE__, __LINE__)
193#else
194int lockmgr __P((struct lock *, u_int flags,
dadab5e9 195 struct simplelock *, struct thread *td));
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196#endif
197void lockmgr_printinfo __P((struct lock *));
dadab5e9 198int lockstatus __P((struct lock *, struct thread *));
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199int lockcount __P((struct lock *));
200
201#ifdef SIMPLELOCK_DEBUG
202void _simple_unlock __P((struct simplelock *alp, const char *, int));
203#define simple_unlock(alp) _simple_unlock(alp, __FILE__, __LINE__)
204int _simple_lock_try __P((struct simplelock *alp, const char *, int));
205#define simple_lock_try(alp) _simple_lock_try(alp, __FILE__, __LINE__)
206void _simple_lock __P((struct simplelock *alp, const char *, int));
207#define simple_lock(alp) _simple_lock(alp, __FILE__, __LINE__)
208void simple_lock_init __P((struct simplelock *alp));
209#else /* !SIMPLELOCK_DEBUG */
210#if MAXCPU == 1 /* no multiprocessor locking is necessary */
211#define NULL_SIMPLELOCKS
212#define simple_lock_init(alp)
213#define simple_lock(alp)
214#define simple_lock_try(alp) (1) /* always succeeds */
215#define simple_unlock(alp)
216#endif /* MAXCPU == 1 */
217#endif /* !SIMPLELOCK_DEBUG */
218
219#endif /* !_LOCK_H_ */