1 /*- 2 * SPDX-License-Identifier: BSD-2-Clause 3 * 4 * Copyright (c) 2006 John Baldwin <jhb@FreeBSD.org> 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 16 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 18 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 19 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 21 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 22 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 23 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 24 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 25 * SUCH DAMAGE. 26 */ 27 28 #ifndef _SYS_RWLOCK_H_ 29 #define _SYS_RWLOCK_H_ 30 31 #include <sys/_lock.h> 32 #include <sys/_rwlock.h> 33 #include <sys/lock_profile.h> 34 #include <sys/lockstat.h> 35 36 #ifdef _KERNEL 37 #include <sys/pcpu.h> 38 #include <machine/atomic.h> 39 #endif 40 41 /* 42 * The rw_lock field consists of several fields. The low bit indicates 43 * if the lock is locked with a read (shared) or write (exclusive) lock. 44 * A value of 0 indicates a write lock, and a value of 1 indicates a read 45 * lock. Bit 1 is a boolean indicating if there are any threads waiting 46 * for a read lock. Bit 2 is a boolean indicating if there are any threads 47 * waiting for a write lock. The rest of the variable's definition is 48 * dependent on the value of the first bit. For a write lock, it is a 49 * pointer to the thread holding the lock, similar to the mtx_lock field of 50 * mutexes. For read locks, it is a count of read locks that are held. 51 * 52 * When the lock is not locked by any thread, it is encoded as a read lock 53 * with zero waiters. 54 */ 55 56 #define RW_LOCK_READ 0x01 57 #define RW_LOCK_READ_WAITERS 0x02 58 #define RW_LOCK_WRITE_WAITERS 0x04 59 #define RW_LOCK_WRITE_SPINNER 0x08 60 #define RW_LOCK_WRITER_RECURSED 0x10 61 #define RW_LOCK_FLAGMASK \ 62 (RW_LOCK_READ | RW_LOCK_READ_WAITERS | RW_LOCK_WRITE_WAITERS | \ 63 RW_LOCK_WRITE_SPINNER | RW_LOCK_WRITER_RECURSED) 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 5 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 #define RW_READ_VALUE(x) ((x)->rw_lock) 80 81 /* Very simple operations on rw_lock. */ 82 83 /* Try to obtain a write lock once. */ 84 #define _rw_write_lock(rw, tid) \ 85 atomic_cmpset_acq_ptr(&(rw)->rw_lock, RW_UNLOCKED, (tid)) 86 87 #define _rw_write_lock_fetch(rw, vp, tid) \ 88 atomic_fcmpset_acq_ptr(&(rw)->rw_lock, vp, (tid)) 89 90 /* Release a write lock quickly if there are no waiters. */ 91 #define _rw_write_unlock(rw, tid) \ 92 atomic_cmpset_rel_ptr(&(rw)->rw_lock, (tid), RW_UNLOCKED) 93 94 #define _rw_write_unlock_fetch(rw, tid) \ 95 atomic_fcmpset_rel_ptr(&(rw)->rw_lock, (tid), RW_UNLOCKED) 96 97 /* 98 * Full lock operations that are suitable to be inlined in non-debug 99 * kernels. If the lock cannot be acquired or released trivially then 100 * the work is deferred to another function. 101 */ 102 103 /* Acquire a write lock. */ 104 #define __rw_wlock(rw, tid, file, line) __extension__ ({ \ 105 uintptr_t _tid = (uintptr_t)(tid); \ 106 uintptr_t _v = RW_UNLOCKED; \ 107 \ 108 if (__predict_false(LOCKSTAT_PROFILE_ENABLED(rw__acquire) || \ 109 !_rw_write_lock_fetch((rw), &_v, _tid))) \ 110 _rw_wlock_hard((rw), _v, (file), (line)); \ 111 (void)0; /* ensure void type for expression */ \ 112 }) 113 114 /* Release a write lock. */ 115 #define __rw_wunlock(rw, tid, file, line) __extension__ ({ \ 116 uintptr_t _v = (uintptr_t)(tid); \ 117 \ 118 if (__predict_false(LOCKSTAT_PROFILE_ENABLED(rw__release) || \ 119 !_rw_write_unlock_fetch((rw), &_v))) \ 120 _rw_wunlock_hard((rw), _v, (file), (line)); \ 121 (void)0; /* ensure void type for expression */ \ 122 }) 123 124 /* 125 * Function prototypes. Routines that start with _ are not part of the 126 * external API and should not be called directly. Wrapper macros should 127 * be used instead. 128 */ 129 void _rw_init_flags(volatile uintptr_t *c, const char *name, int opts); 130 void _rw_destroy(volatile uintptr_t *c); 131 void rw_sysinit(void *arg); 132 int _rw_wowned(const volatile uintptr_t *c); 133 void _rw_wlock_cookie(volatile uintptr_t *c, const char *file, int line); 134 int __rw_try_wlock_int(struct rwlock *rw LOCK_FILE_LINE_ARG_DEF); 135 int __rw_try_wlock(volatile uintptr_t *c, const char *file, int line); 136 void _rw_wunlock_cookie(volatile uintptr_t *c, const char *file, int line); 137 void __rw_rlock_int(struct rwlock *rw LOCK_FILE_LINE_ARG_DEF); 138 void __rw_rlock(volatile uintptr_t *c, const char *file, int line); 139 int __rw_try_rlock_int(struct rwlock *rw LOCK_FILE_LINE_ARG_DEF); 140 int __rw_try_rlock(volatile uintptr_t *c, const char *file, int line); 141 void _rw_runlock_cookie_int(struct rwlock *rw LOCK_FILE_LINE_ARG_DEF); 142 void _rw_runlock_cookie(volatile uintptr_t *c, const char *file, int line); 143 void __rw_wlock_hard(volatile uintptr_t *c, uintptr_t v 144 LOCK_FILE_LINE_ARG_DEF); 145 void __rw_wunlock_hard(volatile uintptr_t *c, uintptr_t v 146 LOCK_FILE_LINE_ARG_DEF); 147 int __rw_try_upgrade_int(struct rwlock *rw LOCK_FILE_LINE_ARG_DEF); 148 int __rw_try_upgrade(volatile uintptr_t *c, const char *file, int line); 149 void __rw_downgrade_int(struct rwlock *rw LOCK_FILE_LINE_ARG_DEF); 150 void __rw_downgrade(volatile uintptr_t *c, const char *file, int line); 151 #if defined(INVARIANTS) || defined(INVARIANT_SUPPORT) 152 void __rw_assert(const volatile uintptr_t *c, int what, const char *file, 153 int line); 154 #endif 155 156 /* 157 * Top-level macros to provide lock cookie once the actual rwlock is passed. 158 * They will also prevent passing a malformed object to the rwlock KPI by 159 * failing compilation as the rw_lock reserved member will not be found. 160 */ 161 #define rw_init(rw, n) \ 162 _rw_init_flags(&(rw)->rw_lock, n, 0) 163 #define rw_init_flags(rw, n, o) \ 164 _rw_init_flags(&(rw)->rw_lock, n, o) 165 #define rw_destroy(rw) \ 166 _rw_destroy(&(rw)->rw_lock) 167 #define rw_wowned(rw) \ 168 _rw_wowned(&(rw)->rw_lock) 169 #define _rw_wlock(rw, f, l) \ 170 _rw_wlock_cookie(&(rw)->rw_lock, f, l) 171 #define _rw_try_wlock(rw, f, l) \ 172 __rw_try_wlock(&(rw)->rw_lock, f, l) 173 #define _rw_wunlock(rw, f, l) \ 174 _rw_wunlock_cookie(&(rw)->rw_lock, f, l) 175 #define _rw_try_rlock(rw, f, l) \ 176 __rw_try_rlock(&(rw)->rw_lock, f, l) 177 #if LOCK_DEBUG > 0 178 #define _rw_rlock(rw, f, l) \ 179 __rw_rlock(&(rw)->rw_lock, f, l) 180 #define _rw_runlock(rw, f, l) \ 181 _rw_runlock_cookie(&(rw)->rw_lock, f, l) 182 #else 183 #define _rw_rlock(rw, f, l) \ 184 __rw_rlock_int((struct rwlock *)rw) 185 #define _rw_runlock(rw, f, l) \ 186 _rw_runlock_cookie_int((struct rwlock *)rw) 187 #endif 188 #if LOCK_DEBUG > 0 189 #define _rw_wlock_hard(rw, v, f, l) \ 190 __rw_wlock_hard(&(rw)->rw_lock, v, f, l) 191 #define _rw_wunlock_hard(rw, v, f, l) \ 192 __rw_wunlock_hard(&(rw)->rw_lock, v, f, l) 193 #define _rw_try_upgrade(rw, f, l) \ 194 __rw_try_upgrade(&(rw)->rw_lock, f, l) 195 #define _rw_downgrade(rw, f, l) \ 196 __rw_downgrade(&(rw)->rw_lock, f, l) 197 #else 198 #define _rw_wlock_hard(rw, v, f, l) \ 199 __rw_wlock_hard(&(rw)->rw_lock, v) 200 #define _rw_wunlock_hard(rw, v, f, l) \ 201 __rw_wunlock_hard(&(rw)->rw_lock, v) 202 #define _rw_try_upgrade(rw, f, l) \ 203 __rw_try_upgrade_int(rw) 204 #define _rw_downgrade(rw, f, l) \ 205 __rw_downgrade_int(rw) 206 #endif 207 #if defined(INVARIANTS) || defined(INVARIANT_SUPPORT) 208 #define _rw_assert(rw, w, f, l) \ 209 __rw_assert(&(rw)->rw_lock, w, f, l) 210 #endif 211 212 /* 213 * Public interface for lock operations. 214 */ 215 216 #ifndef LOCK_DEBUG 217 #error LOCK_DEBUG not defined, include <sys/lock.h> before <sys/rwlock.h> 218 #endif 219 #if LOCK_DEBUG > 0 || defined(RWLOCK_NOINLINE) 220 #define rw_wlock(rw) _rw_wlock((rw), LOCK_FILE, LOCK_LINE) 221 #define rw_wunlock(rw) _rw_wunlock((rw), LOCK_FILE, LOCK_LINE) 222 #else 223 #define rw_wlock(rw) \ 224 __rw_wlock((rw), curthread, LOCK_FILE, LOCK_LINE) 225 #define rw_wunlock(rw) \ 226 __rw_wunlock((rw), curthread, LOCK_FILE, LOCK_LINE) 227 #endif 228 #define rw_rlock(rw) _rw_rlock((rw), LOCK_FILE, LOCK_LINE) 229 #define rw_runlock(rw) _rw_runlock((rw), LOCK_FILE, LOCK_LINE) 230 #define rw_try_rlock(rw) _rw_try_rlock((rw), LOCK_FILE, LOCK_LINE) 231 #define rw_try_upgrade(rw) _rw_try_upgrade((rw), LOCK_FILE, LOCK_LINE) 232 #define rw_try_wlock(rw) _rw_try_wlock((rw), LOCK_FILE, LOCK_LINE) 233 #define rw_downgrade(rw) _rw_downgrade((rw), LOCK_FILE, LOCK_LINE) 234 #define rw_unlock(rw) __extension__ ({ \ 235 if (rw_wowned(rw)) \ 236 rw_wunlock(rw); \ 237 else \ 238 rw_runlock(rw); \ 239 (void)0; /* ensure void type for expression */ \ 240 }) 241 #define rw_sleep(chan, rw, pri, wmesg, timo) \ 242 _sleep((chan), &(rw)->lock_object, (pri), (wmesg), \ 243 tick_sbt * (timo), 0, C_HARDCLOCK) 244 245 #define rw_initialized(rw) lock_initialized(&(rw)->lock_object) 246 247 struct rw_args { 248 void *ra_rw; 249 const char *ra_desc; 250 int ra_flags; 251 }; 252 253 #define RW_SYSINIT_FLAGS(name, rw, desc, flags) \ 254 static struct rw_args name##_args = { \ 255 (rw), \ 256 (desc), \ 257 (flags), \ 258 }; \ 259 SYSINIT(name##_rw_sysinit, SI_SUB_LOCK, SI_ORDER_MIDDLE, \ 260 rw_sysinit, &name##_args); \ 261 SYSUNINIT(name##_rw_sysuninit, SI_SUB_LOCK, SI_ORDER_MIDDLE, \ 262 _rw_destroy, __DEVOLATILE(void *, &(rw)->rw_lock)) 263 264 #define RW_SYSINIT(name, rw, desc) RW_SYSINIT_FLAGS(name, rw, desc, 0) 265 266 /* 267 * Options passed to rw_init_flags(). 268 */ 269 #define RW_DUPOK 0x01 270 #define RW_NOPROFILE 0x02 271 #define RW_NOWITNESS 0x04 272 #define RW_QUIET 0x08 273 #define RW_RECURSE 0x10 274 #define RW_NEW 0x20 275 276 /* 277 * The INVARIANTS-enabled rw_assert() functionality. 278 * 279 * The constants need to be defined for INVARIANT_SUPPORT infrastructure 280 * support as _rw_assert() itself uses them and the latter implies that 281 * _rw_assert() must build. 282 */ 283 #if defined(INVARIANTS) || defined(INVARIANT_SUPPORT) 284 #define RA_LOCKED LA_LOCKED 285 #define RA_RLOCKED LA_SLOCKED 286 #define RA_WLOCKED LA_XLOCKED 287 #define RA_UNLOCKED LA_UNLOCKED 288 #define RA_RECURSED LA_RECURSED 289 #define RA_NOTRECURSED LA_NOTRECURSED 290 #endif 291 292 #ifdef INVARIANTS 293 #define rw_assert(rw, what) _rw_assert((rw), (what), LOCK_FILE, LOCK_LINE) 294 #else 295 #define rw_assert(rw, what) 296 #endif 297 298 #endif /* _KERNEL */ 299 #endif /* !_SYS_RWLOCK_H_ */ 300