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 * 80 * LK_SHARED 81 * Get one of many possible shared locks. If a process holding an 82 * exclusive lock requests a shared lock, the exclusive lock(s) will 83 * be downgraded to shared locks. 84 * 85 * LK_EXCLUSIVE 86 * Stop further shared locks, when they are cleared, grant a pending 87 * upgrade if it exists, then grant an exclusive lock. Only one exclusive 88 * lock may exist at a time, except that a process holding an exclusive 89 * lock may get additional exclusive locks if it explicitly sets the 90 * LK_CANRECURSE flag in the lock request, or if the LK_CANRECURSE flag 91 * was set when the lock was initialized. 92 * 93 * LK_UPGRADE 94 * The process must hold a shared lock that it wants to have upgraded 95 * to an exclusive lock. Other processes may get exclusive access to 96 * the resource between the time that the upgrade is requested and the 97 * time that it is granted. 98 * 99 * LK_EXCLUPGRADE 100 * the process must hold a shared lock that it wants to have upgraded 101 * to an exclusive lock. If the request succeeds, no other processes 102 * will have gotten exclusive access to the resource between the time 103 * that the upgrade is requested and the time that it is granted. 104 * However, if another process has already requested an upgrade, the 105 * request will fail (see error returns below). 106 * 107 * LK_DOWNGRADE 108 * The process must hold an exclusive lock that it wants to have 109 * downgraded to a shared lock. If the process holds multiple (recursive) 110 * exclusive locks, they will all be downgraded to shared locks. 111 * 112 * LK_RELEASE 113 * Release one instance of a lock. 114 * 115 * LK_CANCEL_BEG 116 * The current exclusive lock holder can cancel any blocked lock requests, 117 * or any new requests, whos callers specified LK_CANCELABLE. They will 118 * receive a ENOLCK error code. Cancel beg/end does not stack. 119 * 120 * The cancel command stays in effect until the exclusive lock holder 121 * releases the last count on the lock or issues a LK_CANCEL_END command. 122 * 123 * LK_CANCEL_END 124 * The current exclusive lock holder can stop canceling new requests 125 * whos callers specify LK_CANCELABLE. The exclusive lock is maintained. 126 * 127 * Note that the last release of the exclusive lock will also 128 * automatically end cancel mode. 129 * 130 * 131 * --- 132 * 133 * LK_EXCLOTHER - return for lockstatus(). Used when another process 134 * holds the lock exclusively. 135 * 136 * These are flags that are passed to the lockmgr routine. 137 */ 138 #define LK_TYPE_MASK 0x0000000f /* type of lock sought */ 139 #define LK_SHARED 0x00000001 /* shared lock */ 140 #define LK_EXCLUSIVE 0x00000002 /* exclusive lock */ 141 #define LK_UPGRADE 0x00000003 /* shared-to-exclusive upgrade */ 142 #define LK_EXCLUPGRADE 0x00000004 /* first shared-to-exclusive upgrade */ 143 #define LK_DOWNGRADE 0x00000005 /* exclusive-to-shared downgrade */ 144 #define LK_RELEASE 0x00000006 /* release any type of lock */ 145 #define LK_WAITUPGRADE 0x00000007 146 #define LK_EXCLOTHER 0x00000008 /* other process holds lock */ 147 #define LK_CANCEL_BEG 0x00000009 /* cancel other requests */ 148 #define LK_CANCEL_END 0x0000000a /* stop canceling other requests */ 149 150 /* 151 * lk_count bit fields. 152 * 153 * Positive count is exclusive, negative count is shared. The count field 154 * must be large enough to accomodate all possible threads. 155 */ 156 #define LKC_EXREQ 0x80000000 /* waiting for exclusive lock */ 157 #define LKC_SHREQ 0x40000000 /* waiting for shared lock */ 158 #define LKC_UPREQ 0x20000000 /* waiting for upgrade */ 159 #define LKC_EXCL 0x10000000 /* exclusive (else shr or unlcoked) */ 160 #define LKC_UPGRANT 0x08000000 /* upgrade granted */ 161 #define LKC_CANCEL 0x04000000 /* cancel in effect */ 162 #define LKC_MASK 0x03FFFFFF 163 164 /* 165 * External lock flags. 166 * 167 * The first three flags may be set in lock_init to set their mode permanently, 168 * or passed in as arguments to the lock manager. 169 */ 170 #define LK_EXTFLG_MASK 0x07000070 /* mask of external flags */ 171 #define LK_NOWAIT 0x00000010 /* do not sleep to await lock */ 172 #define LK_SLEEPFAIL 0x00000020 /* sleep, then return failure */ 173 #define LK_CANRECURSE 0x00000040 /* allow recursive exclusive lock */ 174 #define LK_CANCELABLE 0x01000000 /* blocked caller can be canceled */ 175 #define LK_TIMELOCK 0x02000000 176 #define LK_PCATCH 0x04000000 /* timelocked with signal catching */ 177 178 /* 179 * Control flags 180 * 181 * Non-persistent external flags. 182 */ 183 #define LK_FAILRECLAIM 0x00010000 /* vn_lock: allowed to fail on reclaim */ 184 #define LK_RETRY 0x00020000 /* vn_lock: retry until locked */ 185 #define LK_UNUSED40000 0x00040000 186 #define LK_UNUSED80000 0x00080000 187 188 /* 189 * Lock return status. 190 * 191 * Successfully obtained locks return 0. Locks will always succeed 192 * unless one of the following is true: 193 * LK_FORCEUPGRADE is requested and some other process has already 194 * requested a lock upgrade (returns EBUSY). 195 * LK_WAIT is set and a sleep would be required (returns EBUSY). 196 * LK_SLEEPFAIL is set and a sleep was done (returns ENOLCK). 197 * PCATCH is set in lock priority and a signal arrives (returns 198 * either EINTR or ERESTART if system calls is to be restarted). 199 * Non-null lock timeout and timeout expires (returns EWOULDBLOCK). 200 * A failed lock attempt always returns a non-zero error value. No lock 201 * is held after an error return (in particular, a failed LK_UPGRADE 202 * or LK_FORCEUPGRADE will have released its shared access lock). 203 */ 204 205 /* 206 * Indicator that no process holds exclusive lock 207 */ 208 #define LK_KERNTHREAD ((struct thread *)-2) 209 #define LK_NOTHREAD ((struct thread *)-1) 210 211 #ifdef _KERNEL 212 213 void dumplockinfo(struct lock *lkp); 214 struct proc; 215 216 struct lock_args { 217 struct lock *la_lock; 218 const char *la_desc; 219 int la_flags; 220 }; 221 222 #define LOCK_INITIALIZER(wmesg, timo, flags) \ 223 { \ 224 .lk_flags = ((flags) & LK_EXTFLG_MASK), \ 225 .lk_count = 0, \ 226 .lk_wmesg = wmesg, \ 227 .lk_timo = (timo), \ 228 .lk_lockholder = LK_NOTHREAD \ 229 } 230 231 void lockinit (struct lock *, const char *wmesg, int timo, int flags); 232 void lockreinit (struct lock *, const char *wmesg, int timo, int flags); 233 void lockuninit(struct lock *); 234 void lock_sysinit(struct lock_args *); 235 #ifdef DEBUG_LOCKS 236 int debuglockmgr (struct lock *, u_int flags, 237 const char *, 238 const char *, 239 int); 240 #define lockmgr(lockp, flags) \ 241 debuglockmgr((lockp), (flags), "lockmgr", __FILE__, __LINE__) 242 #else 243 int lockmgr (struct lock *, u_int flags); 244 #endif 245 void lockmgr_setexclusive_interlocked(struct lock *); 246 void lockmgr_clrexclusive_interlocked(struct lock *); 247 void lockmgr_kernproc (struct lock *); 248 void lockmgr_printinfo (struct lock *); 249 int lockstatus (struct lock *, struct thread *); 250 int lockowned (struct lock *); 251 int lockcount (struct lock *); 252 int lockcountnb (struct lock *); 253 254 #define LOCK_SYSINIT(name, lock, desc, flags) \ 255 static struct lock_args name##_args = { \ 256 (lock), \ 257 (desc), \ 258 (flags) \ 259 }; \ 260 SYSINIT(name##_lock_sysinit, SI_SUB_DRIVERS, SI_ORDER_MIDDLE, \ 261 lock_sysinit, &name##_args); \ 262 SYSUNINIT(name##_lock_sysuninit, SI_SUB_DRIVERS, SI_ORDER_MIDDLE, \ 263 lockuninit, (lock)) 264 265 #endif /* _KERNEL */ 266 #endif /* _KERNEL || _KERNEL_STRUCTURES */ 267 #endif /* _SYS_LOCK_H_ */ 268