Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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FreeBSD/Linux Kernel Cross Reference
sys/sys/rwlock.h
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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 * 3. Neither the name of the author nor the names of any co-contributors 14 * may be used to endorse or promote products derived from this software 15 * without specific prior written permission. 16 * 17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 20 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 27 * SUCH DAMAGE. 28 * 29 * $FreeBSD: releng/10.0/sys/sys/rwlock.h 247787 2013-03-04 12:48:41Z davide $ 30 */ 31 32 #ifndef _SYS_RWLOCK_H_ 33 #define _SYS_RWLOCK_H_ 34 35 #include <sys/_lock.h> 36 #include <sys/_rwlock.h> 37 #include <sys/lock_profile.h> 38 #include <sys/lockstat.h> 39 40 #ifdef _KERNEL 41 #include <sys/pcpu.h> 42 #include <machine/atomic.h> 43 #endif 44 45 /* 46 * The rw_lock field consists of several fields. The low bit indicates 47 * if the lock is locked with a read (shared) or write (exclusive) lock. 48 * A value of 0 indicates a write lock, and a value of 1 indicates a read 49 * lock. Bit 1 is a boolean indicating if there are any threads waiting 50 * for a read lock. Bit 2 is a boolean indicating if there are any threads 51 * waiting for a write lock. The rest of the variable's definition is 52 * dependent on the value of the first bit. For a write lock, it is a 53 * pointer to the thread holding the lock, similar to the mtx_lock field of 54 * mutexes. For read locks, it is a count of read locks that are held. 55 * 56 * When the lock is not locked by any thread, it is encoded as a read lock 57 * with zero waiters. 58 */ 59 60 #define RW_LOCK_READ 0x01 61 #define RW_LOCK_READ_WAITERS 0x02 62 #define RW_LOCK_WRITE_WAITERS 0x04 63 #define RW_LOCK_WRITE_SPINNER 0x08 64 #define RW_LOCK_FLAGMASK \ 65 (RW_LOCK_READ | RW_LOCK_READ_WAITERS | RW_LOCK_WRITE_WAITERS | \ 66 RW_LOCK_WRITE_SPINNER) 67 #define RW_LOCK_WAITERS (RW_LOCK_READ_WAITERS | RW_LOCK_WRITE_WAITERS) 68 69 #define RW_OWNER(x) ((x) & ~RW_LOCK_FLAGMASK) 70 #define RW_READERS_SHIFT 4 71 #define RW_READERS(x) (RW_OWNER((x)) >> RW_READERS_SHIFT) 72 #define RW_READERS_LOCK(x) ((x) << RW_READERS_SHIFT | RW_LOCK_READ) 73 #define RW_ONE_READER (1 << RW_READERS_SHIFT) 74 75 #define RW_UNLOCKED RW_READERS_LOCK(0) 76 #define RW_DESTROYED (RW_LOCK_READ_WAITERS | RW_LOCK_WRITE_WAITERS) 77 78 #ifdef _KERNEL 79 80 #define rw_recurse lock_object.lo_data 81 82 /* Very simple operations on rw_lock. */ 83 84 /* Try to obtain a write lock once. */ 85 #define _rw_write_lock(rw, tid) \ 86 atomic_cmpset_acq_ptr(&(rw)->rw_lock, RW_UNLOCKED, (tid)) 87 88 /* Release a write lock quickly if there are no waiters. */ 89 #define _rw_write_unlock(rw, tid) \ 90 atomic_cmpset_rel_ptr(&(rw)->rw_lock, (tid), RW_UNLOCKED) 91 92 /* 93 * Full lock operations that are suitable to be inlined in non-debug 94 * kernels. If the lock cannot be acquired or released trivially then 95 * the work is deferred to another function. 96 */ 97 98 /* Acquire a write lock. */ 99 #define __rw_wlock(rw, tid, file, line) do { \ 100 uintptr_t _tid = (uintptr_t)(tid); \ 101 \ 102 if (!_rw_write_lock((rw), _tid)) \ 103 _rw_wlock_hard((rw), _tid, (file), (line)); \ 104 else \ 105 LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(LS_RW_WLOCK_ACQUIRE, \ 106 rw, 0, 0, (file), (line)); \ 107 } while (0) 108 109 /* Release a write lock. */ 110 #define __rw_wunlock(rw, tid, file, line) do { \ 111 uintptr_t _tid = (uintptr_t)(tid); \ 112 \ 113 if ((rw)->rw_recurse) \ 114 (rw)->rw_recurse--; \ 115 else if (!_rw_write_unlock((rw), _tid)) \ 116 _rw_wunlock_hard((rw), _tid, (file), (line)); \ 117 } while (0) 118 119 /* 120 * Function prototypes. Routines that start with _ are not part of the 121 * external API and should not be called directly. Wrapper macros should 122 * be used instead. 123 */ 124 void _rw_init_flags(volatile uintptr_t *c, const char *name, int opts); 125 void _rw_destroy(volatile uintptr_t *c); 126 void rw_sysinit(void *arg); 127 void rw_sysinit_flags(void *arg); 128 int _rw_wowned(const volatile uintptr_t *c); 129 void _rw_wlock_cookie(volatile uintptr_t *c, const char *file, int line); 130 int __rw_try_wlock(volatile uintptr_t *c, const char *file, int line); 131 void _rw_wunlock_cookie(volatile uintptr_t *c, const char *file, int line); 132 void __rw_rlock(volatile uintptr_t *c, const char *file, int line); 133 int __rw_try_rlock(volatile uintptr_t *c, const char *file, int line); 134 void _rw_runlock_cookie(volatile uintptr_t *c, const char *file, int line); 135 void __rw_wlock_hard(volatile uintptr_t *c, uintptr_t tid, const char *file, 136 int line); 137 void __rw_wunlock_hard(volatile uintptr_t *c, uintptr_t tid, 138 const char *file, int line); 139 int __rw_try_upgrade(volatile uintptr_t *c, const char *file, int line); 140 void __rw_downgrade(volatile uintptr_t *c, const char *file, int line); 141 #if defined(INVARIANTS) || defined(INVARIANT_SUPPORT) 142 void __rw_assert(const volatile uintptr_t *c, int what, const char *file, 143 int line); 144 #endif 145 146 /* 147 * Top-level macros to provide lock cookie once the actual rwlock is passed. 148 * They will also prevent passing a malformed object to the rwlock KPI by 149 * failing compilation as the rw_lock reserved member will not be found. 150 */ 151 #define rw_init(rw, n) \ 152 _rw_init_flags(&(rw)->rw_lock, n, 0) 153 #define rw_init_flags(rw, n, o) \ 154 _rw_init_flags(&(rw)->rw_lock, n, o) 155 #define rw_destroy(rw) \ 156 _rw_destroy(&(rw)->rw_lock) 157 #define rw_wowned(rw) \ 158 _rw_wowned(&(rw)->rw_lock) 159 #define _rw_wlock(rw, f, l) \ 160 _rw_wlock_cookie(&(rw)->rw_lock, f, l) 161 #define _rw_try_wlock(rw, f, l) \ 162 __rw_try_wlock(&(rw)->rw_lock, f, l) 163 #define _rw_wunlock(rw, f, l) \ 164 _rw_wunlock_cookie(&(rw)->rw_lock, f, l) 165 #define _rw_rlock(rw, f, l) \ 166 __rw_rlock(&(rw)->rw_lock, f, l) 167 #define _rw_try_rlock(rw, f, l) \ 168 __rw_try_rlock(&(rw)->rw_lock, f, l) 169 #define _rw_runlock(rw, f, l) \ 170 _rw_runlock_cookie(&(rw)->rw_lock, f, l) 171 #define _rw_wlock_hard(rw, t, f, l) \ 172 __rw_wlock_hard(&(rw)->rw_lock, t, f, l) 173 #define _rw_wunlock_hard(rw, t, f, l) \ 174 __rw_wunlock_hard(&(rw)->rw_lock, t, f, l) 175 #define _rw_try_upgrade(rw, f, l) \ 176 __rw_try_upgrade(&(rw)->rw_lock, f, l) 177 #define _rw_downgrade(rw, f, l) \ 178 __rw_downgrade(&(rw)->rw_lock, f, l) 179 #if defined(INVARIANTS) || defined(INVARIANT_SUPPORT) 180 #define _rw_assert(rw, w, f, l) \ 181 __rw_assert(&(rw)->rw_lock, w, f, l) 182 #endif 183 184 185 /* 186 * Public interface for lock operations. 187 */ 188 189 #ifndef LOCK_DEBUG 190 #error LOCK_DEBUG not defined, include <sys/lock.h> before <sys/rwlock.h> 191 #endif 192 #if LOCK_DEBUG > 0 || defined(RWLOCK_NOINLINE) 193 #define rw_wlock(rw) _rw_wlock((rw), LOCK_FILE, LOCK_LINE) 194 #define rw_wunlock(rw) _rw_wunlock((rw), LOCK_FILE, LOCK_LINE) 195 #else 196 #define rw_wlock(rw) \ 197 __rw_wlock((rw), curthread, LOCK_FILE, LOCK_LINE) 198 #define rw_wunlock(rw) \ 199 __rw_wunlock((rw), curthread, LOCK_FILE, LOCK_LINE) 200 #endif 201 #define rw_rlock(rw) _rw_rlock((rw), LOCK_FILE, LOCK_LINE) 202 #define rw_runlock(rw) _rw_runlock((rw), LOCK_FILE, LOCK_LINE) 203 #define rw_try_rlock(rw) _rw_try_rlock((rw), LOCK_FILE, LOCK_LINE) 204 #define rw_try_upgrade(rw) _rw_try_upgrade((rw), LOCK_FILE, LOCK_LINE) 205 #define rw_try_wlock(rw) _rw_try_wlock((rw), LOCK_FILE, LOCK_LINE) 206 #define rw_downgrade(rw) _rw_downgrade((rw), LOCK_FILE, LOCK_LINE) 207 #define rw_unlock(rw) do { \ 208 if (rw_wowned(rw)) \ 209 rw_wunlock(rw); \ 210 else \ 211 rw_runlock(rw); \ 212 } while (0) 213 #define rw_sleep(chan, rw, pri, wmesg, timo) \ 214 _sleep((chan), &(rw)->lock_object, (pri), (wmesg), \ 215 tick_sbt * (timo), 0, C_HARDCLOCK) 216 217 #define rw_initialized(rw) lock_initalized(&(rw)->lock_object) 218 219 struct rw_args { 220 void *ra_rw; 221 const char *ra_desc; 222 }; 223 224 struct rw_args_flags { 225 void *ra_rw; 226 const char *ra_desc; 227 int ra_flags; 228 }; 229 230 #define RW_SYSINIT(name, rw, desc) \ 231 static struct rw_args name##_args = { \ 232 (rw), \ 233 (desc), \ 234 }; \ 235 SYSINIT(name##_rw_sysinit, SI_SUB_LOCK, SI_ORDER_MIDDLE, \ 236 rw_sysinit, &name##_args); \ 237 SYSUNINIT(name##_rw_sysuninit, SI_SUB_LOCK, SI_ORDER_MIDDLE, \ 238 _rw_destroy, __DEVOLATILE(void *, &(rw)->rw_lock)) 239 240 241 #define RW_SYSINIT_FLAGS(name, rw, desc, flags) \ 242 static struct rw_args_flags name##_args = { \ 243 (rw), \ 244 (desc), \ 245 (flags), \ 246 }; \ 247 SYSINIT(name##_rw_sysinit, SI_SUB_LOCK, SI_ORDER_MIDDLE, \ 248 rw_sysinit_flags, &name##_args); \ 249 SYSUNINIT(name##_rw_sysuninit, SI_SUB_LOCK, SI_ORDER_MIDDLE, \ 250 _rw_destroy, __DEVOLATILE(void *, &(rw)->rw_lock)) 251 252 /* 253 * Options passed to rw_init_flags(). 254 */ 255 #define RW_DUPOK 0x01 256 #define RW_NOPROFILE 0x02 257 #define RW_NOWITNESS 0x04 258 #define RW_QUIET 0x08 259 #define RW_RECURSE 0x10 260 261 /* 262 * The INVARIANTS-enabled rw_assert() functionality. 263 * 264 * The constants need to be defined for INVARIANT_SUPPORT infrastructure 265 * support as _rw_assert() itself uses them and the latter implies that 266 * _rw_assert() must build. 267 */ 268 #if defined(INVARIANTS) || defined(INVARIANT_SUPPORT) 269 #define RA_LOCKED LA_LOCKED 270 #define RA_RLOCKED LA_SLOCKED 271 #define RA_WLOCKED LA_XLOCKED 272 #define RA_UNLOCKED LA_UNLOCKED 273 #define RA_RECURSED LA_RECURSED 274 #define RA_NOTRECURSED LA_NOTRECURSED 275 #endif 276 277 #ifdef INVARIANTS 278 #define rw_assert(rw, what) _rw_assert((rw), (what), LOCK_FILE, LOCK_LINE) 279 #else 280 #define rw_assert(rw, what) 281 #endif 282 283 #endif /* _KERNEL */ 284 #endif /* !_SYS_RWLOCK_H_ */
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