1 /* 2 * Copyright (c) 1995 3 * The Regents of the University of California. All rights reserved. 4 * Copyright (c) 2013 5 * The DragonFly Project. All rights reserved. 6 * 7 * This code contains ideas from software contributed to Berkeley by 8 * Avadis Tevanian, Jr., Michael Wayne Young, and the Mach Operating 9 * System project at Carnegie-Mellon University. 10 * 11 * Redistribution and use in source and binary forms, with or without 12 * modification, are permitted provided that the following conditions 13 * are met: 14 * 1. Redistributions of source code must retain the above copyright 15 * notice, this list of conditions and the following disclaimer. 16 * 2. Redistributions in binary form must reproduce the above copyright 17 * notice, this list of conditions and the following disclaimer in the 18 * documentation and/or other materials provided with the distribution. 19 * 3. All advertising materials mentioning features or use of this software 20 * must display the following acknowledgement: 21 * This product includes software developed by the University of 22 * California, Berkeley and its contributors. 23 * 4. Neither the name of the University nor the names of its contributors 24 * may be used to endorse or promote products derived from this software 25 * without specific prior written permission. 26 * 27 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 28 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 29 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 30 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 31 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 32 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 33 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 34 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 35 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 36 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 37 * SUCH DAMAGE. 38 */ 39 40 #ifndef _SYS_LOCK_H_ 41 #define _SYS_LOCK_H_ 42 43 /* 44 * A number of third party programs #include <sys/lock.h> for no good 45 * reason. Don't actually include anything unless we are the kernel. 46 */ 47 #if defined(_KERNEL) || defined(_KERNEL_STRUCTURES) 48 49 #include <machine/lock.h> 50 #ifndef _SYS_THREAD_H_ 51 #include <sys/thread.h> /* lwkt_token */ 52 #endif 53 #ifndef _SYS_SPINLOCK_H_ 54 #include <sys/spinlock.h> 55 #endif 56 57 /* 58 * The general lock structure. Provides for multiple shared locks, 59 * upgrading from shared to exclusive, and sleeping until the lock 60 * can be gained. 61 */ 62 struct thread; 63 64 struct lock { 65 u_int lk_flags; /* see below */ 66 int lk_count; /* -shared, +exclusive */ 67 int lk_timo; /* maximum sleep time (for tsleep) */ 68 const char *lk_wmesg; /* resource sleeping (for tsleep) */ 69 struct thread *lk_lockholder; /* thread of excl lock holder */ 70 #ifdef DEBUG_LOCKS 71 const char *lk_filename; 72 const char *lk_lockername; 73 int lk_lineno; 74 #endif 75 }; 76 77 /* 78 * Lock request types: 79 * LK_SHARED - get one of many possible shared locks. If a process 80 * holding an exclusive lock requests a shared lock, the exclusive 81 * lock(s) will be downgraded to shared locks. 82 * LK_EXCLUSIVE - stop further shared locks, when they are cleared, 83 * grant a pending upgrade if it exists, then grant an exclusive 84 * lock. Only one exclusive lock may exist at a time, except that 85 * a process holding an exclusive lock may get additional exclusive 86 * locks if it explicitly sets the LK_CANRECURSE flag in the lock 87 * request, or if the LK_CANRECUSE flag was set when the lock was 88 * initialized. 89 * LK_UPGRADE - the process must hold a shared lock that it wants to 90 * have upgraded to an exclusive lock. Other processes may get 91 * exclusive access to the resource between the time that the upgrade 92 * is requested and the time that it is granted. 93 * LK_EXCLUPGRADE - the process must hold a shared lock that it wants to 94 * have upgraded to an exclusive lock. If the request succeeds, no 95 * other processes will have gotten exclusive access to the resource 96 * between the time that the upgrade is requested and the time that 97 * it is granted. However, if another process has already requested 98 * an upgrade, the request will fail (see error returns below). 99 * LK_DOWNGRADE - the process must hold an exclusive lock that it wants 100 * to have downgraded to a shared lock. If the process holds multiple 101 * (recursive) exclusive locks, they will all be downgraded to shared 102 * locks. 103 * LK_RELEASE - release one instance of a lock. 104 * LK_EXCLOTHER - return for lockstatus(). Used when another process 105 * holds the lock exclusively. 106 * 107 * These are flags that are passed to the lockmgr routine. 108 */ 109 #define LK_TYPE_MASK 0x0000000f /* type of lock sought */ 110 #define LK_SHARED 0x00000001 /* shared lock */ 111 #define LK_EXCLUSIVE 0x00000002 /* exclusive lock */ 112 #define LK_UPGRADE 0x00000003 /* shared-to-exclusive upgrade */ 113 #define LK_EXCLUPGRADE 0x00000004 /* first shared-to-exclusive upgrade */ 114 #define LK_DOWNGRADE 0x00000005 /* exclusive-to-shared downgrade */ 115 #define LK_RELEASE 0x00000006 /* release any type of lock */ 116 #define LK_WAITUPGRADE 0x00000007 117 #define LK_EXCLOTHER 0x00000008 /* other process holds lock */ 118 119 /* 120 * lk_count bit fields. 121 * 122 * Positive count is exclusive, negative count is shared. 123 */ 124 #define LKC_EXREQ 0x80000000 /* waiting for exclusive lock */ 125 #define LKC_SHREQ 0x40000000 /* waiting for shared lock */ 126 #define LKC_UPREQ 0x20000000 /* waiting for upgrade */ 127 #define LKC_EXCL 0x10000000 /* exclusive (else shr or unlcoked) */ 128 #define LKC_UPGRANT 0x08000000 /* upgrade granted */ 129 #define LKC_MASK 0x07FFFFFF 130 131 /* 132 * External lock flags. 133 * 134 * The first three flags may be set in lock_init to set their mode permanently, 135 * or passed in as arguments to the lock manager. 136 */ 137 #define LK_EXTFLG_MASK 0x07000070 /* mask of external flags */ 138 #define LK_NOWAIT 0x00000010 /* do not sleep to await lock */ 139 #define LK_SLEEPFAIL 0x00000020 /* sleep, then return failure */ 140 #define LK_CANRECURSE 0x00000040 /* allow recursive exclusive lock */ 141 #define LK_UNUSED0080 0x00000080 142 #define LK_UNUSED0100x 0x01000000 143 #define LK_TIMELOCK 0x02000000 144 #define LK_PCATCH 0x04000000 /* timelocked with signal catching */ 145 146 /* 147 * Control flags 148 * 149 * Non-persistent external flags. 150 */ 151 #define LK_FAILRECLAIM 0x00010000 /* vn_lock: allowed to fail on reclaim */ 152 #define LK_RETRY 0x00020000 /* vn_lock: retry until locked */ 153 #define LK_UNUSED40000 0x00040000 154 #define LK_UNUSED80000 0x00080000 155 156 /* 157 * Lock return status. 158 * 159 * Successfully obtained locks return 0. Locks will always succeed 160 * unless one of the following is true: 161 * LK_FORCEUPGRADE is requested and some other process has already 162 * requested a lock upgrade (returns EBUSY). 163 * LK_WAIT is set and a sleep would be required (returns EBUSY). 164 * LK_SLEEPFAIL is set and a sleep was done (returns ENOLCK). 165 * PCATCH is set in lock priority and a signal arrives (returns 166 * either EINTR or ERESTART if system calls is to be restarted). 167 * Non-null lock timeout and timeout expires (returns EWOULDBLOCK). 168 * A failed lock attempt always returns a non-zero error value. No lock 169 * is held after an error return (in particular, a failed LK_UPGRADE 170 * or LK_FORCEUPGRADE will have released its shared access lock). 171 */ 172 173 /* 174 * Indicator that no process holds exclusive lock 175 */ 176 #define LK_KERNTHREAD ((struct thread *)-2) 177 #define LK_NOTHREAD ((struct thread *)-1) 178 179 #ifdef _KERNEL 180 181 void dumplockinfo(struct lock *lkp); 182 struct proc; 183 184 struct lock_args { 185 struct lock *la_lock; 186 const char *la_desc; 187 int la_flags; 188 }; 189 190 void lockinit (struct lock *, const char *wmesg, int timo, int flags); 191 void lockreinit (struct lock *, const char *wmesg, int timo, int flags); 192 void lockuninit(struct lock *); 193 void lock_sysinit(struct lock_args *); 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 #define LOCK_SYSINIT(name, lock, desc, flags) \ 214 static struct lock_args name##_args = { \ 215 (lock), \ 216 (desc), \ 217 (flags) \ 218 }; \ 219 SYSINIT(name##_lock_sysinit, SI_SUB_DRIVERS, SI_ORDER_MIDDLE, \ 220 lock_sysinit, &name##_args); \ 221 SYSUNINIT(name##_lock_sysuninit, SI_SUB_DRIVERS, SI_ORDER_MIDDLE, \ 222 lockuninit, (lock)) 223 224 #endif /* _KERNEL */ 225 #endif /* _KERNEL || _KERNEL_STRUCTURES */ 226 #endif /* _SYS_LOCK_H_ */ 227