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. Neither the name of the University nor the names of its contributors 20 * may be used to endorse or promote products derived from this software 21 * without specific prior written permission. 22 * 23 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 24 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 25 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 26 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 27 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 28 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 29 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 30 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 31 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 32 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 33 * SUCH DAMAGE. 34 */ 35 36 #ifndef _SYS_LOCK_H_ 37 #define _SYS_LOCK_H_ 38 39 /* 40 * A number of third party programs #include <sys/lock.h> for no good 41 * reason. Don't actually include anything unless we are the kernel. 42 */ 43 #if defined(_KERNEL) || defined(_KERNEL_STRUCTURES) 44 45 #include <machine/lock.h> 46 #ifndef _SYS_THREAD_H_ 47 #include <sys/thread.h> /* lwkt_token */ 48 #endif 49 #ifndef _SYS_SPINLOCK_H_ 50 #include <sys/spinlock.h> 51 #endif 52 53 /* 54 * The general lock structure. Provides for multiple shared locks, 55 * upgrading from shared to exclusive, and sleeping until the lock 56 * can be gained. 57 */ 58 struct thread; 59 60 struct lock { 61 u_int lk_flags; /* see below */ 62 int lk_count; /* -shared, +exclusive */ 63 int lk_timo; /* maximum sleep time (for tsleep) */ 64 const char *lk_wmesg; /* resource sleeping (for tsleep) */ 65 struct thread *lk_lockholder; /* thread of excl lock holder */ 66 #ifdef DEBUG_LOCKS 67 const char *lk_filename; 68 const char *lk_lockername; 69 int lk_lineno; 70 #endif 71 }; 72 73 /* 74 * Lock request types: 75 * 76 * LK_SHARED 77 * Get one of many possible shared locks. If a process holding an 78 * exclusive lock requests a shared lock, the exclusive lock(s) will 79 * be downgraded to shared locks. 80 * 81 * LK_EXCLUSIVE 82 * Stop further shared locks, when they are cleared, grant a pending 83 * upgrade if it exists, then grant an exclusive lock. Only one exclusive 84 * lock may exist at a time, except that a process holding an exclusive 85 * lock may get additional exclusive locks if it explicitly sets the 86 * LK_CANRECURSE flag in the lock request, or if the LK_CANRECURSE flag 87 * was set when the lock was initialized. 88 * 89 * LK_UPGRADE 90 * The process must hold a shared lock that it wants to have upgraded 91 * to an exclusive lock. Other processes may get exclusive access to 92 * the resource between the time that the upgrade is requested and the 93 * time that it is granted. 94 * 95 * LK_EXCLUPGRADE 96 * the process must hold a shared lock that it wants to have upgraded 97 * to an exclusive lock. If the request succeeds, no other processes 98 * will have gotten exclusive access to the resource between the time 99 * that the upgrade is requested and the time that it is granted. 100 * However, if another process has already requested an upgrade, the 101 * request will fail (see error returns below). 102 * 103 * LK_DOWNGRADE 104 * The process must hold an exclusive lock that it wants to have 105 * downgraded to a shared lock. If the process holds multiple (recursive) 106 * exclusive locks, they will all be downgraded to shared locks. 107 * 108 * LK_RELEASE 109 * Release one instance of a lock. 110 * 111 * LK_CANCEL_BEG 112 * The current exclusive lock holder can cancel any blocked lock requests, 113 * or any new requests, whos callers specified LK_CANCELABLE. They will 114 * receive a ENOLCK error code. Cancel beg/end does not stack. 115 * 116 * The cancel command stays in effect until the exclusive lock holder 117 * releases the last count on the lock or issues a LK_CANCEL_END command. 118 * 119 * LK_CANCEL_END 120 * The current exclusive lock holder can stop canceling new requests 121 * whos callers specify LK_CANCELABLE. The exclusive lock is maintained. 122 * 123 * Note that the last release of the exclusive lock will also 124 * automatically end cancel mode. 125 * 126 * 127 * --- 128 * 129 * LK_EXCLOTHER - return for lockstatus(). Used when another process 130 * holds the lock exclusively. 131 * 132 * These are flags that are passed to the lockmgr routine. 133 */ 134 #define LK_TYPE_MASK 0x0000000f /* type of lock sought */ 135 #define LK_SHARED 0x00000001 /* shared lock */ 136 #define LK_EXCLUSIVE 0x00000002 /* exclusive lock */ 137 #define LK_UPGRADE 0x00000003 /* shared-to-exclusive upgrade */ 138 #define LK_EXCLUPGRADE 0x00000004 /* first shared-to-exclusive upgrade */ 139 #define LK_DOWNGRADE 0x00000005 /* exclusive-to-shared downgrade */ 140 #define LK_RELEASE 0x00000006 /* release any type of lock */ 141 #define LK_WAITUPGRADE 0x00000007 142 #define LK_EXCLOTHER 0x00000008 /* other process holds lock */ 143 #define LK_CANCEL_BEG 0x00000009 /* cancel other requests */ 144 #define LK_CANCEL_END 0x0000000a /* stop canceling other requests */ 145 146 /* 147 * lk_count bit fields. 148 * 149 * Positive count is exclusive, negative count is shared. The count field 150 * must be large enough to accomodate all possible threads. 151 */ 152 #define LKC_EXREQ 0x80000000 /* waiting for exclusive lock */ 153 #define LKC_SHREQ 0x40000000 /* waiting for shared lock */ 154 #define LKC_UPREQ 0x20000000 /* waiting for upgrade */ 155 #define LKC_EXCL 0x10000000 /* exclusive (else shr or unlocked) */ 156 #define LKC_UPGRANT 0x08000000 /* upgrade granted */ 157 #define LKC_CANCEL 0x04000000 /* cancel in effect */ 158 #define LKC_MASK 0x03FFFFFF 159 160 /* 161 * External lock flags. 162 * 163 * The first three flags may be set in lock_init to set their mode permanently, 164 * or passed in as arguments to the lock manager. 165 */ 166 #define LK_EXTFLG_MASK 0x07000070 /* mask of external flags */ 167 #define LK_NOWAIT 0x00000010 /* do not sleep to await lock */ 168 #define LK_SLEEPFAIL 0x00000020 /* sleep, then return failure */ 169 #define LK_CANRECURSE 0x00000040 /* allow recursive exclusive lock */ 170 #define LK_CANCELABLE 0x01000000 /* blocked caller can be canceled */ 171 #define LK_TIMELOCK 0x02000000 172 #define LK_PCATCH 0x04000000 /* timelocked with signal catching */ 173 174 /* 175 * Control flags 176 * 177 * Non-persistent external flags. 178 */ 179 #define LK_FAILRECLAIM 0x00010000 /* vn_lock: allowed to fail on reclaim */ 180 #define LK_RETRY 0x00020000 /* vn_lock: retry until locked */ 181 #define LK_UNUSED40000 0x00040000 182 #define LK_UNUSED80000 0x00080000 183 184 /* 185 * Lock return status. 186 * 187 * Successfully obtained locks return 0. Locks will always succeed 188 * unless one of the following is true: 189 * LK_FORCEUPGRADE is requested and some other process has already 190 * requested a lock upgrade (returns EBUSY). 191 * LK_WAIT is set and a sleep would be required (returns EBUSY). 192 * LK_SLEEPFAIL is set and a sleep was done (returns ENOLCK). 193 * PCATCH is set in lock priority and a signal arrives (returns 194 * either EINTR or ERESTART if system calls is to be restarted). 195 * Non-null lock timeout and timeout expires (returns EWOULDBLOCK). 196 * A failed lock attempt always returns a non-zero error value. No lock 197 * is held after an error return (in particular, a failed LK_UPGRADE 198 * or LK_FORCEUPGRADE will have released its shared access lock). 199 */ 200 201 /* 202 * Indicator that no process holds exclusive lock 203 */ 204 #define LK_KERNTHREAD ((struct thread *)-2) 205 #define LK_NOTHREAD ((struct thread *)-1) 206 207 #ifdef _KERNEL 208 209 void dumplockinfo(struct lock *lkp); 210 struct proc; 211 212 struct lock_args { 213 struct lock *la_lock; 214 const char *la_desc; 215 int la_flags; 216 }; 217 218 #define LOCK_INITIALIZER(wmesg, timo, flags) \ 219 { \ 220 .lk_flags = ((flags) & LK_EXTFLG_MASK), \ 221 .lk_count = 0, \ 222 .lk_wmesg = wmesg, \ 223 .lk_timo = (timo), \ 224 .lk_lockholder = LK_NOTHREAD \ 225 } 226 227 void lockinit (struct lock *, const char *wmesg, int timo, int flags); 228 void lockreinit (struct lock *, const char *wmesg, int timo, int flags); 229 void lockuninit(struct lock *); 230 void lock_sysinit(struct lock_args *); 231 #ifdef DEBUG_LOCKS 232 int debuglockmgr (struct lock *, u_int flags, 233 const char *, 234 const char *, 235 int); 236 #define lockmgr(lockp, flags) \ 237 debuglockmgr((lockp), (flags), "lockmgr", __FILE__, __LINE__) 238 #else 239 int lockmgr (struct lock *, u_int flags); 240 #endif 241 void lockmgr_setexclusive_interlocked(struct lock *); 242 void lockmgr_clrexclusive_interlocked(struct lock *); 243 void lockmgr_kernproc (struct lock *); 244 void lockmgr_printinfo (struct lock *); 245 int lockstatus (struct lock *, struct thread *); 246 int lockowned (struct lock *); 247 int lockcount (struct lock *); 248 int lockcountnb (struct lock *); 249 250 #define LOCK_SYSINIT(name, lock, desc, flags) \ 251 static struct lock_args name##_args = { \ 252 (lock), \ 253 (desc), \ 254 (flags) \ 255 }; \ 256 SYSINIT(name##_lock_sysinit, SI_SUB_DRIVERS, SI_ORDER_MIDDLE, \ 257 lock_sysinit, &name##_args); \ 258 SYSUNINIT(name##_lock_sysuninit, SI_SUB_DRIVERS, SI_ORDER_MIDDLE, \ 259 lockuninit, (lock)) 260 261 #endif /* _KERNEL */ 262 #endif /* _KERNEL || _KERNEL_STRUCTURES */ 263 #endif /* _SYS_LOCK_H_ */ 264