1 /*- 2 * Copyright (c) 2006 John Baldwin <jhb@FreeBSD.org> 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 24 * SUCH DAMAGE. 25 * 26 * $FreeBSD: stable/9/sys/sys/rwlock.h 262192 2014-02-18 20:27:17Z jhb $ 27 */ 28 29 #ifndef _SYS_RWLOCK_H_ 30 #define _SYS_RWLOCK_H_ 31 32 #include <sys/_lock.h> 33 #include <sys/_rwlock.h> 34 #include <sys/lock_profile.h> 35 #include <sys/lockstat.h> 36 37 #ifdef _KERNEL 38 #include <sys/pcpu.h> 39 #include <machine/atomic.h> 40 #endif 41 42 /* 43 * The rw_lock field consists of several fields. The low bit indicates 44 * if the lock is locked with a read (shared) or write (exclusive) lock. 45 * A value of 0 indicates a write lock, and a value of 1 indicates a read 46 * lock. Bit 1 is a boolean indicating if there are any threads waiting 47 * for a read lock. Bit 2 is a boolean indicating if there are any threads 48 * waiting for a write lock. The rest of the variable's definition is 49 * dependent on the value of the first bit. For a write lock, it is a 50 * pointer to the thread holding the lock, similar to the mtx_lock field of 51 * mutexes. For read locks, it is a count of read locks that are held. 52 * 53 * When the lock is not locked by any thread, it is encoded as a read lock 54 * with zero waiters. 55 */ 56 57 #define RW_LOCK_READ 0x01 58 #define RW_LOCK_READ_WAITERS 0x02 59 #define RW_LOCK_WRITE_WAITERS 0x04 60 #define RW_LOCK_WRITE_SPINNER 0x08 61 #define RW_LOCK_FLAGMASK \ 62 (RW_LOCK_READ | RW_LOCK_READ_WAITERS | RW_LOCK_WRITE_WAITERS | \ 63 RW_LOCK_WRITE_SPINNER) 64 #define RW_LOCK_WAITERS (RW_LOCK_READ_WAITERS | RW_LOCK_WRITE_WAITERS) 65 66 #define RW_OWNER(x) ((x) & ~RW_LOCK_FLAGMASK) 67 #define RW_READERS_SHIFT 4 68 #define RW_READERS(x) (RW_OWNER((x)) >> RW_READERS_SHIFT) 69 #define RW_READERS_LOCK(x) ((x) << RW_READERS_SHIFT | RW_LOCK_READ) 70 #define RW_ONE_READER (1 << RW_READERS_SHIFT) 71 72 #define RW_UNLOCKED RW_READERS_LOCK(0) 73 #define RW_DESTROYED (RW_LOCK_READ_WAITERS | RW_LOCK_WRITE_WAITERS) 74 75 #ifdef _KERNEL 76 77 #define rw_recurse lock_object.lo_data 78 79 /* Very simple operations on rw_lock. */ 80 81 /* Try to obtain a write lock once. */ 82 #define _rw_write_lock(rw, tid) \ 83 atomic_cmpset_acq_ptr(&(rw)->rw_lock, RW_UNLOCKED, (tid)) 84 85 /* Release a write lock quickly if there are no waiters. */ 86 #define _rw_write_unlock(rw, tid) \ 87 atomic_cmpset_rel_ptr(&(rw)->rw_lock, (tid), RW_UNLOCKED) 88 89 /* 90 * Full lock operations that are suitable to be inlined in non-debug 91 * kernels. If the lock cannot be acquired or released trivially then 92 * the work is deferred to another function. 93 */ 94 95 /* Acquire a write lock. */ 96 #define __rw_wlock(rw, tid, file, line) do { \ 97 uintptr_t _tid = (uintptr_t)(tid); \ 98 \ 99 if (!_rw_write_lock((rw), _tid)) \ 100 _rw_wlock_hard((rw), _tid, (file), (line)); \ 101 else \ 102 LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(LS_RW_WLOCK_ACQUIRE, \ 103 rw, 0, 0, (file), (line)); \ 104 } while (0) 105 106 /* Release a write lock. */ 107 #define __rw_wunlock(rw, tid, file, line) do { \ 108 uintptr_t _tid = (uintptr_t)(tid); \ 109 \ 110 if ((rw)->rw_recurse) \ 111 (rw)->rw_recurse--; \ 112 else if (!_rw_write_unlock((rw), _tid)) \ 113 _rw_wunlock_hard((rw), _tid, (file), (line)); \ 114 } while (0) 115 116 /* 117 * Function prototypes. Routines that start with _ are not part of the 118 * external API and should not be called directly. Wrapper macros should 119 * be used instead. 120 */ 121 122 #define rw_init(rw, name) rw_init_flags((rw), (name), 0) 123 void rw_init_flags(struct rwlock *rw, const char *name, int opts); 124 void rw_destroy(struct rwlock *rw); 125 void rw_sysinit(void *arg); 126 void rw_sysinit_flags(void *arg); 127 int rw_wowned(struct rwlock *rw); 128 void _rw_wlock(struct rwlock *rw, const char *file, int line); 129 int _rw_try_wlock(struct rwlock *rw, const char *file, int line); 130 void _rw_wunlock(struct rwlock *rw, const char *file, int line); 131 void _rw_rlock(struct rwlock *rw, const char *file, int line); 132 int _rw_try_rlock(struct rwlock *rw, const char *file, int line); 133 void _rw_runlock(struct rwlock *rw, const char *file, int line); 134 void _rw_wlock_hard(struct rwlock *rw, uintptr_t tid, const char *file, 135 int line); 136 void _rw_wunlock_hard(struct rwlock *rw, uintptr_t tid, const char *file, 137 int line); 138 int _rw_try_upgrade(struct rwlock *rw, const char *file, int line); 139 void _rw_downgrade(struct rwlock *rw, const char *file, int line); 140 #if defined(INVARIANTS) || defined(INVARIANT_SUPPORT) 141 void _rw_assert(struct rwlock *rw, int what, const char *file, int line); 142 #endif 143 144 /* 145 * Public interface for lock operations. 146 */ 147 148 #ifndef LOCK_DEBUG 149 #error LOCK_DEBUG not defined, include <sys/lock.h> before <sys/rwlock.h> 150 #endif 151 #if LOCK_DEBUG > 0 || defined(RWLOCK_NOINLINE) 152 #define rw_wlock(rw) _rw_wlock((rw), LOCK_FILE, LOCK_LINE) 153 #define rw_wunlock(rw) _rw_wunlock((rw), LOCK_FILE, LOCK_LINE) 154 #else 155 #define rw_wlock(rw) \ 156 __rw_wlock((rw), curthread, LOCK_FILE, LOCK_LINE) 157 #define rw_wunlock(rw) \ 158 __rw_wunlock((rw), curthread, LOCK_FILE, LOCK_LINE) 159 #endif 160 #define rw_rlock(rw) _rw_rlock((rw), LOCK_FILE, LOCK_LINE) 161 #define rw_runlock(rw) _rw_runlock((rw), LOCK_FILE, LOCK_LINE) 162 #define rw_try_rlock(rw) _rw_try_rlock((rw), LOCK_FILE, LOCK_LINE) 163 #define rw_try_upgrade(rw) _rw_try_upgrade((rw), LOCK_FILE, LOCK_LINE) 164 #define rw_try_wlock(rw) _rw_try_wlock((rw), LOCK_FILE, LOCK_LINE) 165 #define rw_downgrade(rw) _rw_downgrade((rw), LOCK_FILE, LOCK_LINE) 166 #define rw_unlock(rw) do { \ 167 if (rw_wowned(rw)) \ 168 rw_wunlock(rw); \ 169 else \ 170 rw_runlock(rw); \ 171 } while (0) 172 #define rw_sleep(chan, rw, pri, wmesg, timo) \ 173 _sleep((chan), &(rw)->lock_object, (pri), (wmesg), (timo)) 174 175 #define rw_initialized(rw) lock_initalized(&(rw)->lock_object) 176 177 struct rw_args { 178 struct rwlock *ra_rw; 179 const char *ra_desc; 180 }; 181 182 struct rw_args_flags { 183 struct rwlock *ra_rw; 184 const char *ra_desc; 185 int ra_flags; 186 }; 187 188 #define RW_SYSINIT(name, rw, desc) \ 189 static struct rw_args name##_args = { \ 190 (rw), \ 191 (desc), \ 192 }; \ 193 SYSINIT(name##_rw_sysinit, SI_SUB_LOCK, SI_ORDER_MIDDLE, \ 194 rw_sysinit, &name##_args); \ 195 SYSUNINIT(name##_rw_sysuninit, SI_SUB_LOCK, SI_ORDER_MIDDLE, \ 196 rw_destroy, (rw)) 197 198 199 #define RW_SYSINIT_FLAGS(name, rw, desc, flags) \ 200 static struct rw_args_flags name##_args = { \ 201 (rw), \ 202 (desc), \ 203 (flags), \ 204 }; \ 205 SYSINIT(name##_rw_sysinit, SI_SUB_LOCK, SI_ORDER_MIDDLE, \ 206 rw_sysinit_flags, &name##_args); \ 207 SYSUNINIT(name##_rw_sysuninit, SI_SUB_LOCK, SI_ORDER_MIDDLE, \ 208 rw_destroy, (rw)) 209 210 /* 211 * Options passed to rw_init_flags(). 212 */ 213 #define RW_DUPOK 0x01 214 #define RW_NOPROFILE 0x02 215 #define RW_NOWITNESS 0x04 216 #define RW_QUIET 0x08 217 #define RW_RECURSE 0x10 218 219 /* 220 * The INVARIANTS-enabled rw_assert() functionality. 221 * 222 * The constants need to be defined for INVARIANT_SUPPORT infrastructure 223 * support as _rw_assert() itself uses them and the latter implies that 224 * _rw_assert() must build. 225 */ 226 #if defined(INVARIANTS) || defined(INVARIANT_SUPPORT) 227 #define RA_LOCKED LA_LOCKED 228 #define RA_RLOCKED LA_SLOCKED 229 #define RA_WLOCKED LA_XLOCKED 230 #define RA_UNLOCKED LA_UNLOCKED 231 #define RA_RECURSED LA_RECURSED 232 #define RA_NOTRECURSED LA_NOTRECURSED 233 #endif 234 235 #ifdef INVARIANTS 236 #define rw_assert(rw, what) _rw_assert((rw), (what), LOCK_FILE, LOCK_LINE) 237 #else 238 #define rw_assert(rw, what) 239 #endif 240 241 #endif /* _KERNEL */ 242 #endif /* !_SYS_RWLOCK_H_ */ 243