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 1.7 2003/11/21 22:46:13 dillon Exp $ 40 */ 41 42 #ifndef _SYS_LOCK_H_ 43 #define _SYS_LOCK_H_ 44 45 /* 46 * A number of third party programs #include <sys/lock.h> for no good 47 * reason. Don't actually include anything unless we are the kernel. 48 */ 49 #if defined(_KERNEL) || defined(_KERNEL_STRUCTURES) 50 51 #include <machine/lock.h> 52 #ifndef _SYS_THREAD_H_ 53 #include <sys/thread.h> /* lwkt_token */ 54 #endif 55 56 /* 57 * The general lock structure. Provides for multiple shared locks, 58 * upgrading from shared to exclusive, and sleeping until the lock 59 * can be gained. 60 */ 61 struct thread; 62 63 struct lock { 64 lwkt_token lk_interlock; /* lock on remaining fields */ 65 u_int lk_flags; /* see below */ 66 int lk_sharecount; /* # of accepted shared locks */ 67 int lk_waitcount; /* # of processes sleeping for lock */ 68 short lk_exclusivecount; /* # of recursive exclusive locks */ 69 short lk_prio; /* tsleep flags */ 70 char *lk_wmesg; /* resource sleeping (for tsleep) */ 71 int lk_timo; /* maximum sleep time (for tsleep) */ 72 struct thread *lk_lockholder; /* thread of excl lock holder */ 73 #ifdef DEBUG_LOCKS 74 const char *lk_filename; 75 const char *lk_lockername; 76 int lk_lineno; 77 #endif 78 }; 79 /* 80 * Lock request types: 81 * LK_SHARED - get one of many possible shared locks. If a process 82 * holding an exclusive lock requests a shared lock, the exclusive 83 * lock(s) will be downgraded to shared locks. 84 * LK_EXCLUSIVE - stop further shared locks, when they are cleared, 85 * grant a pending upgrade if it exists, then grant an exclusive 86 * lock. Only one exclusive lock may exist at a time, except that 87 * a process holding an exclusive lock may get additional exclusive 88 * locks if it explicitly sets the LK_CANRECURSE flag in the lock 89 * request, or if the LK_CANRECUSE flag was set when the lock was 90 * initialized. 91 * LK_UPGRADE - the process must hold a shared lock that it wants to 92 * have upgraded to an exclusive lock. Other processes may get 93 * exclusive access to the resource between the time that the upgrade 94 * is requested and the time that it is granted. 95 * LK_EXCLUPGRADE - the process must hold a shared lock that it wants to 96 * have upgraded to an exclusive lock. If the request succeeds, no 97 * other processes will have gotten exclusive access to the resource 98 * between the time that the upgrade is requested and the time that 99 * it is granted. However, if another process has already requested 100 * an upgrade, the request will fail (see error returns below). 101 * LK_DOWNGRADE - the process must hold an exclusive lock that it wants 102 * to have downgraded to a shared lock. If the process holds multiple 103 * (recursive) exclusive locks, they will all be downgraded to shared 104 * locks. 105 * LK_RELEASE - release one instance of a lock. 106 * LK_DRAIN - wait for all activity on the lock to end, then mark it 107 * decommissioned. This feature is used before freeing a lock that 108 * is part of a piece of memory that is about to be freed. 109 * LK_EXCLOTHER - return for lockstatus(). Used when another process 110 * holds the lock exclusively. 111 * 112 * These are flags that are passed to the lockmgr routine. 113 */ 114 #define LK_TYPE_MASK 0x0000000f /* type of lock sought */ 115 #define LK_SHARED 0x00000001 /* shared lock */ 116 #define LK_EXCLUSIVE 0x00000002 /* exclusive lock */ 117 #define LK_UPGRADE 0x00000003 /* shared-to-exclusive upgrade */ 118 #define LK_EXCLUPGRADE 0x00000004 /* first shared-to-exclusive upgrade */ 119 #define LK_DOWNGRADE 0x00000005 /* exclusive-to-shared downgrade */ 120 #define LK_RELEASE 0x00000006 /* release any type of lock */ 121 #define LK_DRAIN 0x00000007 /* wait for all lock activity to end */ 122 #define LK_EXCLOTHER 0x00000008 /* other process holds lock */ 123 /* 124 * External lock flags. 125 * 126 * The first three flags may be set in lock_init to set their mode permanently, 127 * or passed in as arguments to the lock manager. The LK_REENABLE flag may be 128 * set only at the release of a lock obtained by drain. 129 */ 130 #define LK_EXTFLG_MASK 0x03000070 /* mask of external flags */ 131 #define LK_NOWAIT 0x00000010 /* do not sleep to await lock */ 132 #define LK_SLEEPFAIL 0x00000020 /* sleep, then return failure */ 133 #define LK_CANRECURSE 0x00000040 /* allow recursive exclusive lock */ 134 #define LK_REENABLE 0x00000080 /* lock is be reenabled after drain */ 135 #define LK_NOPAUSE 0x01000000 /* no spinloop */ 136 #define LK_TIMELOCK 0x02000000 137 /* 138 * Internal lock flags. 139 * 140 * These flags are used internally to the lock manager. 141 */ 142 #define LK_WANT_UPGRADE 0x00000100 /* waiting for share-to-excl upgrade */ 143 #define LK_WANT_EXCL 0x00000200 /* exclusive lock sought */ 144 #define LK_HAVE_EXCL 0x00000400 /* exclusive lock obtained */ 145 #define LK_WAITDRAIN 0x00000800 /* process waiting for lock to drain */ 146 #define LK_DRAINING 0x00004000 /* lock is being drained */ 147 /* 148 * Control flags 149 * 150 * Non-persistent external flags. 151 */ 152 #define LK_INTERLOCK 0x00010000 /* unlock passed simple lock after 153 getting lk_interlock */ 154 #define LK_RETRY 0x00020000 /* vn_lock: retry until locked */ 155 #define LK_NOOBJ 0x00040000 /* vget: don't create object */ 156 #define LK_THISLAYER 0x00080000 /* vn_lock: lock/unlock only current layer */ 157 158 /* 159 * Internal state flags corresponding to lk_sharecount, and lk_waitcount 160 */ 161 #define LK_SHARE_NONZERO 0x00100000 162 #define LK_WAIT_NONZERO 0x00200000 163 164 /* 165 * Lock return status. 166 * 167 * Successfully obtained locks return 0. Locks will always succeed 168 * unless one of the following is true: 169 * LK_FORCEUPGRADE is requested and some other process has already 170 * requested a lock upgrade (returns EBUSY). 171 * LK_WAIT is set and a sleep would be required (returns EBUSY). 172 * LK_SLEEPFAIL is set and a sleep was done (returns ENOLCK). 173 * PCATCH is set in lock priority and a signal arrives (returns 174 * either EINTR or ERESTART if system calls is to be restarted). 175 * Non-null lock timeout and timeout expires (returns EWOULDBLOCK). 176 * A failed lock attempt always returns a non-zero error value. No lock 177 * is held after an error return (in particular, a failed LK_UPGRADE 178 * or LK_FORCEUPGRADE will have released its shared access lock). 179 */ 180 181 /* 182 * Indicator that no process holds exclusive lock 183 */ 184 #define LK_KERNTHREAD ((struct thread *)-2) 185 #define LK_NOTHREAD ((struct thread *)-1) 186 187 #ifdef _KERNEL 188 189 void dumplockinfo(struct lock *lkp); 190 struct proc; 191 192 void lockinit (struct lock *, int prio, char *wmesg, int timo, 193 int flags); 194 #ifdef DEBUG_LOCKS 195 int debuglockmgr (struct lock *, u_int flags, 196 struct lwkt_token *, struct thread *p, 197 const char *, 198 const char *, 199 int); 200 #define lockmgr(lockp, flags, slockp, td) \ 201 debuglockmgr((lockp), (flags), (slockp), (td), \ 202 "lockmgr", __FILE__, __LINE__) 203 #else 204 int lockmgr (struct lock *, u_int flags, 205 struct lwkt_token *, struct thread *td); 206 #endif 207 void lockmgr_printinfo (struct lock *); 208 int lockstatus (struct lock *, struct thread *); 209 int lockcount (struct lock *); 210 211 #endif /* _KERNEL */ 212 #endif /* _KERNEL || _KERNEL_STRUCTURES */ 213 #endif /* _SYS_LOCK_H_ */ 214 215