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 $ 39 * $DragonFly: src/sys/sys/lock.h,v 1.5 2003/07/19 21:14:50 dillon Exp $ 40 */ 41 42 #ifndef _LOCK_H_ 43 #define _LOCK_H_ 44 45 #include <machine/lock.h> 46 #ifndef _SYS_THREAD_H_ 47 #include <sys/thread.h> /* lwkt_token */ 48 #endif 49 50 /* 51 * The general lock structure. Provides for multiple shared locks, 52 * upgrading from shared to exclusive, and sleeping until the lock 53 * can be gained. 54 */ 55 struct thread; 56 57 struct lock { 58 lwkt_token lk_interlock; /* lock on remaining fields */ 59 u_int lk_flags; /* see below */ 60 int lk_sharecount; /* # of accepted shared locks */ 61 int lk_waitcount; /* # of processes sleeping for lock */ 62 short lk_exclusivecount; /* # of recursive exclusive locks */ 63 short lk_prio; /* tsleep flags */ 64 char *lk_wmesg; /* resource sleeping (for tsleep) */ 65 int lk_timo; /* maximum sleep time (for tsleep) */ 66 struct thread *lk_lockholder; /* thread of excl lock holder */ 67 #ifdef DEBUG_LOCKS 68 const char *lk_filename; 69 const char *lk_lockername; 70 int lk_lineno; 71 #endif 72 }; 73 /* 74 * Lock request types: 75 * LK_SHARED - get one of many possible shared locks. If a process 76 * holding an exclusive lock requests a shared lock, the exclusive 77 * lock(s) will be downgraded to shared locks. 78 * LK_EXCLUSIVE - stop further shared locks, when they are cleared, 79 * grant a pending upgrade if it exists, then grant an exclusive 80 * lock. Only one exclusive lock may exist at a time, except that 81 * a process holding an exclusive lock may get additional exclusive 82 * locks if it explicitly sets the LK_CANRECURSE flag in the lock 83 * request, or if the LK_CANRECUSE flag was set when the lock was 84 * initialized. 85 * LK_UPGRADE - the process must hold a shared lock that it wants to 86 * have upgraded to an exclusive lock. Other processes may get 87 * exclusive access to the resource between the time that the upgrade 88 * is requested and the time that it is granted. 89 * LK_EXCLUPGRADE - the process must hold a shared lock that it wants to 90 * have upgraded to an exclusive lock. If the request succeeds, no 91 * other processes will have gotten exclusive access to the resource 92 * between the time that the upgrade is requested and the time that 93 * it is granted. However, if another process has already requested 94 * an upgrade, the request will fail (see error returns below). 95 * LK_DOWNGRADE - the process must hold an exclusive lock that it wants 96 * to have downgraded to a shared lock. If the process holds multiple 97 * (recursive) exclusive locks, they will all be downgraded to shared 98 * locks. 99 * LK_RELEASE - release one instance of a lock. 100 * LK_DRAIN - wait for all activity on the lock to end, then mark it 101 * decommissioned. This feature is used before freeing a lock that 102 * is part of a piece of memory that is about to be freed. 103 * LK_EXCLOTHER - return for lockstatus(). Used when another process 104 * holds the lock exclusively. 105 * 106 * These are flags that are passed to the lockmgr routine. 107 */ 108 #define LK_TYPE_MASK 0x0000000f /* type of lock sought */ 109 #define LK_SHARED 0x00000001 /* shared lock */ 110 #define LK_EXCLUSIVE 0x00000002 /* exclusive lock */ 111 #define LK_UPGRADE 0x00000003 /* shared-to-exclusive upgrade */ 112 #define LK_EXCLUPGRADE 0x00000004 /* first shared-to-exclusive upgrade */ 113 #define LK_DOWNGRADE 0x00000005 /* exclusive-to-shared downgrade */ 114 #define LK_RELEASE 0x00000006 /* release any type of lock */ 115 #define LK_DRAIN 0x00000007 /* wait for all lock activity to end */ 116 #define LK_EXCLOTHER 0x00000008 /* other process holds lock */ 117 /* 118 * External lock flags. 119 * 120 * The first three flags may be set in lock_init to set their mode permanently, 121 * or passed in as arguments to the lock manager. The LK_REENABLE flag may be 122 * set only at the release of a lock obtained by drain. 123 */ 124 #define LK_EXTFLG_MASK 0x03000070 /* mask of external flags */ 125 #define LK_NOWAIT 0x00000010 /* do not sleep to await lock */ 126 #define LK_SLEEPFAIL 0x00000020 /* sleep, then return failure */ 127 #define LK_CANRECURSE 0x00000040 /* allow recursive exclusive lock */ 128 #define LK_REENABLE 0x00000080 /* lock is be reenabled after drain */ 129 #define LK_NOPAUSE 0x01000000 /* no spinloop */ 130 #define LK_TIMELOCK 0x02000000 131 /* 132 * Internal lock flags. 133 * 134 * These flags are used internally to the lock manager. 135 */ 136 #define LK_WANT_UPGRADE 0x00000100 /* waiting for share-to-excl upgrade */ 137 #define LK_WANT_EXCL 0x00000200 /* exclusive lock sought */ 138 #define LK_HAVE_EXCL 0x00000400 /* exclusive lock obtained */ 139 #define LK_WAITDRAIN 0x00000800 /* process waiting for lock to drain */ 140 #define LK_DRAINING 0x00004000 /* lock is being drained */ 141 /* 142 * Control flags 143 * 144 * Non-persistent external flags. 145 */ 146 #define LK_INTERLOCK 0x00010000 /* unlock passed simple lock after 147 getting lk_interlock */ 148 #define LK_RETRY 0x00020000 /* vn_lock: retry until locked */ 149 #define LK_NOOBJ 0x00040000 /* vget: don't create object */ 150 #define LK_THISLAYER 0x00080000 /* vn_lock: lock/unlock only current layer */ 151 152 /* 153 * Internal state flags corresponding to lk_sharecount, and lk_waitcount 154 */ 155 #define LK_SHARE_NONZERO 0x00100000 156 #define LK_WAIT_NONZERO 0x00200000 157 158 /* 159 * Lock return status. 160 * 161 * Successfully obtained locks return 0. Locks will always succeed 162 * unless one of the following is true: 163 * LK_FORCEUPGRADE is requested and some other process has already 164 * requested a lock upgrade (returns EBUSY). 165 * LK_WAIT is set and a sleep would be required (returns EBUSY). 166 * LK_SLEEPFAIL is set and a sleep was done (returns ENOLCK). 167 * PCATCH is set in lock priority and a signal arrives (returns 168 * either EINTR or ERESTART if system calls is to be restarted). 169 * Non-null lock timeout and timeout expires (returns EWOULDBLOCK). 170 * A failed lock attempt always returns a non-zero error value. No lock 171 * is held after an error return (in particular, a failed LK_UPGRADE 172 * or LK_FORCEUPGRADE will have released its shared access lock). 173 */ 174 175 /* 176 * Indicator that no process holds exclusive lock 177 */ 178 #define LK_KERNTHREAD ((struct thread *)-2) 179 #define LK_NOTHREAD ((struct thread *)-1) 180 181 void dumplockinfo(struct lock *lkp); 182 struct proc; 183 184 void lockinit __P((struct lock *, int prio, char *wmesg, int timo, 185 int flags)); 186 #ifdef DEBUG_LOCKS 187 int debuglockmgr __P((struct lock *, u_int flags, 188 struct lwkt_token *, struct thread *p, 189 const char *, 190 const char *, 191 int)); 192 #define lockmgr(lockp, flags, slockp, td) \ 193 debuglockmgr((lockp), (flags), (slockp), (td), \ 194 "lockmgr", __FILE__, __LINE__) 195 #else 196 int lockmgr __P((struct lock *, u_int flags, 197 struct lwkt_token *, struct thread *td)); 198 #endif 199 void lockmgr_printinfo __P((struct lock *)); 200 int lockstatus __P((struct lock *, struct thread *)); 201 int lockcount __P((struct lock *)); 202 203 #endif /* !_LOCK_H_ */ 204