lockmgr.h revision 176320
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 * 4. Neither the name of the University nor the names of its contributors 18 * may be used to endorse or promote products derived from this software 19 * without specific prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31 * SUCH DAMAGE. 32 * 33 * @(#)lock.h 8.12 (Berkeley) 5/19/95 34 * $FreeBSD: head/sys/sys/lockmgr.h 176320 2008-02-15 21:04:36Z attilio $ 35 */ 36 37#ifndef _SYS_LOCKMGR_H_ 38#define _SYS_LOCKMGR_H_ 39 40#ifdef DEBUG_LOCKS 41#include <sys/stack.h> /* XXX */ 42#endif 43#include <sys/queue.h> 44#include <sys/lock.h> 45 46struct mtx; 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. 52 */ 53struct lock { 54 struct lock_object lk_object; /* common lock properties */ 55 struct mtx *lk_interlock; /* lock on remaining fields */ 56 u_int lk_flags; /* see below */ 57 int lk_sharecount; /* # of accepted shared locks */ 58 int lk_waitcount; /* # of processes sleeping for lock */ 59 short lk_exclusivecount; /* # of recursive exclusive locks */ 60 short lk_prio; /* priority at which to sleep */ 61 int lk_timo; /* maximum sleep time (for tsleep) */ 62 struct thread *lk_lockholder; /* thread of exclusive lock holder */ 63 struct lock *lk_newlock; /* lock taking over this lock */ 64 65#ifdef DEBUG_LOCKS 66 struct stack lk_stack; 67#endif 68}; 69 70#define lk_wmesg lk_object.lo_name 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_DOWNGRADE - the process must hold an exclusive lock that it wants 88 * to have downgraded to a shared lock. If the process holds multiple 89 * (recursive) exclusive locks, they will all be downgraded to shared 90 * locks. 91 * LK_RELEASE - release one instance of a lock. 92 * LK_DRAIN - wait for all activity on the lock to end, then mark it 93 * decommissioned. This feature is used before freeing a lock that 94 * is part of a piece of memory that is about to be freed. 95 * LK_EXCLOTHER - return for lockstatus(). Used when another process 96 * holds the lock exclusively. 97 * 98 * These are flags that are passed to the lockmgr routine. 99 */ 100#define LK_TYPE_MASK 0x0000000f /* type of lock sought */ 101#define LK_SHARED 0x00000001 /* shared lock */ 102#define LK_EXCLUSIVE 0x00000002 /* exclusive lock */ 103#define LK_UPGRADE 0x00000003 /* shared-to-exclusive upgrade */ 104#define LK_DOWNGRADE 0x00000005 /* exclusive-to-shared downgrade */ 105#define LK_RELEASE 0x00000006 /* release any type of lock */ 106#define LK_DRAIN 0x00000007 /* wait for all lock activity to end */ 107#define LK_EXCLOTHER 0x00000008 /* other process holds lock */ 108/* 109 * External lock flags. 110 * 111 * These may be set in lock_init to set their mode permanently, 112 * or passed in as arguments to the lock manager. 113 */ 114#define LK_EXTFLG_MASK 0x00000ff0 /* mask of external flags */ 115#define LK_NOWAIT 0x00000010 /* do not sleep to await lock */ 116#define LK_SLEEPFAIL 0x00000020 /* sleep, then return failure */ 117#define LK_CANRECURSE 0x00000040 /* allow recursive exclusive lock */ 118#define LK_NOSHARE 0x00000080 /* Only allow exclusive locks */ 119#define LK_TIMELOCK 0x00000100 /* use lk_timo, else no timeout */ 120#define LK_NOWITNESS 0x00000200 /* disable WITNESS */ 121#define LK_NODUP 0x00000400 /* enable duplication logging */ 122/* 123 * Nonpersistent external flags. 124 */ 125#define LK_RETRY 0x00001000 /* vn_lock: retry until locked */ 126#define LK_INTERLOCK 0x00002000 /* 127 * unlock passed mutex after getting 128 * lk_interlock 129 */ 130/* 131 * Internal lock flags. 132 * 133 * These flags are used internally to the lock manager. 134 */ 135#define LK_WANT_UPGRADE 0x00010000 /* waiting for share-to-excl upgrade */ 136#define LK_WANT_EXCL 0x00020000 /* exclusive lock sought */ 137#define LK_HAVE_EXCL 0x00040000 /* exclusive lock obtained */ 138#define LK_WAITDRAIN 0x00080000 /* process waiting for lock to drain */ 139#define LK_DRAINING 0x00100000 /* lock is being drained */ 140#define LK_DESTROYED 0x00200000 /* lock is destroyed */ 141/* 142 * Internal state flags corresponding to lk_sharecount, and lk_waitcount 143 */ 144#define LK_SHARE_NONZERO 0x01000000 145#define LK_WAIT_NONZERO 0x02000000 146 147/* 148 * Default values for lockmgr_args(). 149 */ 150#define LK_WMESG_DEFAULT (NULL) 151#define LK_PRIO_DEFAULT (-1) 152#define LK_TIMO_DEFAULT (0) 153 154/* 155 * Assertion flags. 156 */ 157#if defined(INVARIANTS) || defined(INVARIANT_SUPPORT) 158#define KA_BASE (LA_MASKASSERT + 1) 159#define KA_LOCKED LA_LOCKED 160#define KA_SLOCKED LA_SLOCKED 161#define KA_XLOCKED LA_XLOCKED 162#define KA_UNLOCKED LA_UNLOCKED 163#define KA_RECURSED LA_RECURSED 164#define KA_NOTRECURSED LA_NOTRECURSED 165#define KA_HELD (KA_BASE << 0x00) 166#define KA_UNHELD (KA_BASE << 0x01) 167#endif 168 169/* 170 * Lock return status. 171 * 172 * Successfully obtained locks return 0. Locks will always succeed 173 * unless one of the following is true: 174 * LK_FORCEUPGRADE is requested and some other process has already 175 * requested a lock upgrade (returns EBUSY). 176 * LK_WAIT is set and a sleep would be required (returns EBUSY). 177 * LK_SLEEPFAIL is set and a sleep was done (returns ENOLCK). 178 * PCATCH is set in lock priority and a signal arrives (returns 179 * either EINTR or ERESTART if system calls is to be restarted). 180 * Non-null lock timeout and timeout expires (returns EWOULDBLOCK). 181 * A failed lock attempt always returns a non-zero error value. No lock 182 * is held after an error return (in particular, a failed LK_UPGRADE 183 * or LK_FORCEUPGRADE will have released its shared access lock). 184 */ 185 186/* 187 * Indicator that no process holds exclusive lock 188 */ 189#define LK_KERNPROC ((struct thread *)-2) 190#define LK_NOPROC ((struct thread *) -1) 191 192struct thread; 193 194void lockinit(struct lock *, int prio, const char *wmesg, 195 int timo, int flags); 196void lockdestroy(struct lock *); 197 198int _lockmgr_args(struct lock *, u_int flags, struct mtx *, 199 const char *wmesg, int prio, int timo, char *file, int line); 200#if defined(INVARIANTS) || defined(INVARIANT_SUPPORT) 201void _lockmgr_assert(struct lock *, int what, const char *, int); 202#endif 203void _lockmgr_disown(struct lock *, const char *, int); 204void lockmgr_printinfo(struct lock *); 205int lockstatus(struct lock *, struct thread *); 206int lockwaiters(struct lock *); 207 208#define lockmgr(lock, flags, mtx) \ 209 _lockmgr_args((lock), (flags), (mtx), LK_WMESG_DEFAULT, \ 210 LK_PRIO_DEFAULT, LK_TIMO_DEFAULT, LOCK_FILE, LOCK_LINE) 211#define lockmgr_disown(lock) \ 212 _lockmgr_disown((lock), LOCK_FILE, LOCK_LINE) 213#define lockmgr_args(lock, flags, mtx, wmesg, prio, timo) \ 214 _lockmgr_args((lock), (flags), (mtx), (wmesg), (prio), (timo), \ 215 LOCK_FILE, LOCK_LINE) 216#define lockmgr_recursed(lkp) \ 217 ((lkp)->lk_exclusivecount > 1) 218#ifdef INVARIANTS 219#define lockmgr_assert(lkp, what) \ 220 _lockmgr_assert((lkp), (what), LOCK_FILE, LOCK_LINE) 221#else 222#define lockmgr_assert(lkp, what) 223#endif 224#ifdef DDB 225int lockmgr_chain(struct thread *td, struct thread **ownerp); 226#endif 227 228#endif /* !_SYS_LOCKMGR_H_ */ 229