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 1.12 2006/03/02 19:08:00 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 #ifndef _SYS_SPINLOCK_H_ 56 #include <sys/spinlock.h> 57 #endif 58 59 /* 60 * The general lock structure. Provides for multiple shared locks, 61 * upgrading from shared to exclusive, and sleeping until the lock 62 * can be gained. 63 */ 64 struct thread; 65 66 struct lock { 67 struct spinlock lk_spinlock; /* lock on remaining fields */ 68 u_int lk_flags; /* see below */ 69 int lk_sharecount; /* # of accepted shared locks */ 70 int lk_waitcount; /* # of processes sleeping for lock */ 71 short lk_exclusivecount; /* # of recursive exclusive locks */ 72 short lk_unused1; 73 char *lk_wmesg; /* resource sleeping (for tsleep) */ 74 int lk_timo; /* maximum sleep time (for tsleep) */ 75 struct thread *lk_lockholder; /* thread of excl lock holder */ 76 #ifdef DEBUG_LOCKS 77 const char *lk_filename; 78 const char *lk_lockername; 79 int lk_lineno; 80 #endif 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_UPGRADE - the process must hold a shared lock that it wants to 95 * have upgraded to an exclusive lock. Other processes may get 96 * exclusive access to the resource between the time that the upgrade 97 * is requested and the time that it is granted. 98 * LK_EXCLUPGRADE - the process must hold a shared lock that it wants to 99 * have upgraded to an exclusive lock. If the request succeeds, no 100 * other processes will have gotten exclusive access to the resource 101 * between the time that the upgrade is requested and the time that 102 * it is granted. However, if another process has already requested 103 * an upgrade, the request will fail (see error returns below). 104 * LK_DOWNGRADE - the process must hold an exclusive lock that it wants 105 * to have downgraded to a shared lock. If the process holds multiple 106 * (recursive) exclusive locks, they will all be downgraded to shared 107 * locks. 108 * LK_RELEASE - release one instance of a lock. 109 * LK_DRAIN - wait for all activity on the lock to end, then mark it 110 * decommissioned. This feature is used before freeing a lock that 111 * is part of a piece of memory that is about to be freed. 112 * LK_EXCLOTHER - return for lockstatus(). Used when another process 113 * holds the lock exclusively. 114 * 115 * These are flags that are passed to the lockmgr routine. 116 */ 117 #define LK_TYPE_MASK 0x0000000f /* type of lock sought */ 118 #define LK_SHARED 0x00000001 /* shared lock */ 119 #define LK_EXCLUSIVE 0x00000002 /* exclusive lock */ 120 #define LK_UPGRADE 0x00000003 /* shared-to-exclusive upgrade */ 121 #define LK_EXCLUPGRADE 0x00000004 /* first shared-to-exclusive upgrade */ 122 #define LK_DOWNGRADE 0x00000005 /* exclusive-to-shared downgrade */ 123 #define LK_RELEASE 0x00000006 /* release any type of lock */ 124 #define LK_DRAIN 0x00000007 /* wait for all lock activity to end */ 125 #define LK_EXCLOTHER 0x00000008 /* other process holds lock */ 126 /* 127 * External lock flags. 128 * 129 * The first three flags may be set in lock_init to set their mode permanently, 130 * or passed in as arguments to the lock manager. The LK_REENABLE flag may be 131 * set only at the release of a lock obtained by drain. 132 */ 133 #define LK_EXTFLG_MASK 0x07000070 /* mask of external flags */ 134 #define LK_NOWAIT 0x00000010 /* do not sleep to await lock */ 135 #define LK_SLEEPFAIL 0x00000020 /* sleep, then return failure */ 136 #define LK_CANRECURSE 0x00000040 /* allow recursive exclusive lock */ 137 #define LK_REENABLE 0x00000080 /* lock is be reenabled after drain */ 138 #define LK_NOPAUSE 0x01000000 /* no spinloop */ 139 #define LK_TIMELOCK 0x02000000 140 #define LK_PCATCH 0x04000000 /* timelocked with signal catching */ 141 /* 142 * Internal lock flags. 143 * 144 * These flags are used internally to the lock manager. 145 */ 146 #define LK_WANT_UPGRADE 0x00000100 /* waiting for share-to-excl upgrade */ 147 #define LK_WANT_EXCL 0x00000200 /* exclusive lock sought */ 148 #define LK_HAVE_EXCL 0x00000400 /* exclusive lock obtained */ 149 #define LK_WAITDRAIN 0x00000800 /* process waiting for lock to drain */ 150 #define LK_DRAINING 0x00004000 /* lock is being drained */ 151 /* 152 * Control flags 153 * 154 * Non-persistent external flags. 155 */ 156 #define LK_INTERLOCK 0x00010000 /* unlock passed simple lock after 157 getting lk_spinlock */ 158 #define LK_RETRY 0x00020000 /* vn_lock: retry until locked */ 159 #define LK_NOOBJ 0x00040000 /* vget: don't create object */ 160 #define LK_THISLAYER 0x00080000 /* vn_lock: lock/unlock only current layer */ 161 162 /* 163 * Internal state flags corresponding to lk_sharecount, and lk_waitcount 164 */ 165 #define LK_SHARE_NONZERO 0x00100000 166 #define LK_WAIT_NONZERO 0x00200000 167 168 /* 169 * Lock return status. 170 * 171 * Successfully obtained locks return 0. Locks will always succeed 172 * unless one of the following is true: 173 * LK_FORCEUPGRADE is requested and some other process has already 174 * requested a lock upgrade (returns EBUSY). 175 * LK_WAIT is set and a sleep would be required (returns EBUSY). 176 * LK_SLEEPFAIL is set and a sleep was done (returns ENOLCK). 177 * PCATCH is set in lock priority and a signal arrives (returns 178 * either EINTR or ERESTART if system calls is to be restarted). 179 * Non-null lock timeout and timeout expires (returns EWOULDBLOCK). 180 * A failed lock attempt always returns a non-zero error value. No lock 181 * is held after an error return (in particular, a failed LK_UPGRADE 182 * or LK_FORCEUPGRADE will have released its shared access lock). 183 */ 184 185 /* 186 * Indicator that no process holds exclusive lock 187 */ 188 #define LK_KERNTHREAD ((struct thread *)-2) 189 #define LK_NOTHREAD ((struct thread *)-1) 190 191 #ifdef _KERNEL 192 193 void dumplockinfo(struct lock *lkp); 194 struct proc; 195 196 void lockinit (struct lock *, char *wmesg, int timo, int flags); 197 void lockreinit (struct lock *, char *wmesg, int timo, int flags); 198 #ifdef DEBUG_LOCKS 199 int debuglockmgr (struct lock *, u_int flags, 200 struct spinlock *, struct thread *p, 201 const char *, 202 const char *, 203 int); 204 #define lockmgr(lockp, flags, slockp, td) \ 205 debuglockmgr((lockp), (flags), (slockp), (td), \ 206 "lockmgr", __FILE__, __LINE__) 207 #else 208 int lockmgr (struct lock *, u_int flags, 209 struct spinlock *, struct thread *td); 210 #endif 211 void lockmgr_printinfo (struct lock *); 212 int lockstatus (struct lock *, struct thread *); 213 int lockcount (struct lock *); 214 int lockcountnb (struct lock *); 215 216 #endif /* _KERNEL */ 217 #endif /* _KERNEL || _KERNEL_STRUCTURES */ 218 #endif /* _SYS_LOCK_H_ */ 219 220