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 1.19 2007/08/20 05:44:58 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_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_UNUSED07 0x00000007 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. 128 */ 129 #define LK_EXTFLG_MASK 0x07000070 /* mask of external flags */ 130 #define LK_NOWAIT 0x00000010 /* do not sleep to await lock */ 131 #define LK_SLEEPFAIL 0x00000020 /* sleep, then return failure */ 132 #define LK_CANRECURSE 0x00000040 /* allow recursive exclusive lock */ 133 #define LK_UNUSED0080 0x00000080 134 #define LK_NOSPINWAIT 0x01000000 /* don't wait for spinlock */ 135 #define LK_TIMELOCK 0x02000000 136 #define LK_PCATCH 0x04000000 /* timelocked with signal catching */ 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_UNUSED0800 0x00000800 146 #define LK_UNUSED4000 0x00004000 147 /* 148 * Control flags 149 * 150 * Non-persistent external flags. 151 */ 152 #define LK_UNUSED10000 0x00010000 153 #define LK_RETRY 0x00020000 /* vn_lock: retry until locked */ 154 #define LK_NOOBJ 0x00040000 /* vget: don't create object */ 155 #define LK_THISLAYER 0x00080000 /* vn_lock: lock/unlock only current layer */ 156 157 /* 158 * Internal state flags corresponding to lk_sharecount, and lk_waitcount 159 */ 160 #define LK_SHARE_NONZERO 0x00100000 161 #define LK_WAIT_NONZERO 0x00200000 162 163 /* 164 * Lock return status. 165 * 166 * Successfully obtained locks return 0. Locks will always succeed 167 * unless one of the following is true: 168 * LK_FORCEUPGRADE is requested and some other process has already 169 * requested a lock upgrade (returns EBUSY). 170 * LK_WAIT is set and a sleep would be required (returns EBUSY). 171 * LK_SLEEPFAIL is set and a sleep was done (returns ENOLCK). 172 * PCATCH is set in lock priority and a signal arrives (returns 173 * either EINTR or ERESTART if system calls is to be restarted). 174 * Non-null lock timeout and timeout expires (returns EWOULDBLOCK). 175 * A failed lock attempt always returns a non-zero error value. No lock 176 * is held after an error return (in particular, a failed LK_UPGRADE 177 * or LK_FORCEUPGRADE will have released its shared access lock). 178 */ 179 180 /* 181 * Indicator that no process holds exclusive lock 182 */ 183 #define LK_KERNTHREAD ((struct thread *)-2) 184 #define LK_NOTHREAD ((struct thread *)-1) 185 186 #ifdef _KERNEL 187 188 void dumplockinfo(struct lock *lkp); 189 struct proc; 190 191 void lockinit (struct lock *, char *wmesg, int timo, int flags); 192 void lockreinit (struct lock *, char *wmesg, int timo, int flags); 193 void lockuninit(struct lock *); 194 #ifdef DEBUG_LOCKS 195 int debuglockmgr (struct lock *, u_int flags, 196 const char *, 197 const char *, 198 int); 199 #define lockmgr(lockp, flags) \ 200 debuglockmgr((lockp), (flags), "lockmgr", __FILE__, __LINE__) 201 #else 202 int lockmgr (struct lock *, u_int flags); 203 #endif 204 void lockmgr_setexclusive_interlocked(struct lock *); 205 void lockmgr_clrexclusive_interlocked(struct lock *); 206 void lockmgr_kernproc (struct lock *); 207 void lockmgr_printinfo (struct lock *); 208 int lockstatus (struct lock *, struct thread *); 209 int lockowned (struct lock *); 210 int lockcount (struct lock *); 211 int lockcountnb (struct lock *); 212 213 #endif /* _KERNEL */ 214 #endif /* _KERNEL || _KERNEL_STRUCTURES */ 215 #endif /* _SYS_LOCK_H_ */ 216 217