1 /*- 2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD 3 * 4 * Copyright (c) 2006 John Baldwin <jhb@FreeBSD.org> 5 * All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 19 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26 * SUCH DAMAGE. 27 * 28 * $FreeBSD$ 29 */ 30 31 #ifndef _SYS_RWLOCK_H_ 32 #define _SYS_RWLOCK_H_ 33 34 #include <sys/_lock.h> 35 #include <sys/_rwlock.h> 36 #include <sys/lock_profile.h> 37 #include <sys/lockstat.h> 38 39 #ifdef _KERNEL 40 #include <sys/pcpu.h> 41 #include <machine/atomic.h> 42 #endif 43 44 /* 45 * The rw_lock field consists of several fields. The low bit indicates 46 * if the lock is locked with a read (shared) or write (exclusive) lock. 47 * A value of 0 indicates a write lock, and a value of 1 indicates a read 48 * lock. Bit 1 is a boolean indicating if there are any threads waiting 49 * for a read lock. Bit 2 is a boolean indicating if there are any threads 50 * waiting for a write lock. The rest of the variable's definition is 51 * dependent on the value of the first bit. For a write lock, it is a 52 * pointer to the thread holding the lock, similar to the mtx_lock field of 53 * mutexes. For read locks, it is a count of read locks that are held. 54 * 55 * When the lock is not locked by any thread, it is encoded as a read lock 56 * with zero waiters. 57 */ 58 59 #define RW_LOCK_READ 0x01 60 #define RW_LOCK_READ_WAITERS 0x02 61 #define RW_LOCK_WRITE_WAITERS 0x04 62 #define RW_LOCK_WRITE_SPINNER 0x08 63 #define RW_LOCK_WRITER_RECURSED 0x10 64 #define RW_LOCK_FLAGMASK \ 65 (RW_LOCK_READ | RW_LOCK_READ_WAITERS | RW_LOCK_WRITE_WAITERS | \ 66 RW_LOCK_WRITE_SPINNER | RW_LOCK_WRITER_RECURSED) 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 5 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 #define RW_READ_VALUE(x) ((x)->rw_lock) 83 84 /* Very simple operations on rw_lock. */ 85 86 /* Try to obtain a write lock once. */ 87 #define _rw_write_lock(rw, tid) \ 88 atomic_cmpset_acq_ptr(&(rw)->rw_lock, RW_UNLOCKED, (tid)) 89 90 #define _rw_write_lock_fetch(rw, vp, tid) \ 91 atomic_fcmpset_acq_ptr(&(rw)->rw_lock, vp, (tid)) 92 93 /* Release a write lock quickly if there are no waiters. */ 94 #define _rw_write_unlock(rw, tid) \ 95 atomic_cmpset_rel_ptr(&(rw)->rw_lock, (tid), RW_UNLOCKED) 96 97 #define _rw_write_unlock_fetch(rw, tid) \ 98 atomic_fcmpset_rel_ptr(&(rw)->rw_lock, (tid), RW_UNLOCKED) 99 100 /* 101 * Full lock operations that are suitable to be inlined in non-debug 102 * kernels. If the lock cannot be acquired or released trivially then 103 * the work is deferred to another function. 104 */ 105 106 /* Acquire a write lock. */ 107 #define __rw_wlock(rw, tid, file, line) do { \ 108 uintptr_t _tid = (uintptr_t)(tid); \ 109 uintptr_t _v = RW_UNLOCKED; \ 110 \ 111 if (__predict_false(LOCKSTAT_PROFILE_ENABLED(rw__acquire) || \ 112 !_rw_write_lock_fetch((rw), &_v, _tid))) \ 113 _rw_wlock_hard((rw), _v, (file), (line)); \ 114 } while (0) 115 116 /* Release a write lock. */ 117 #define __rw_wunlock(rw, tid, file, line) do { \ 118 uintptr_t _v = (uintptr_t)(tid); \ 119 \ 120 if (__predict_false(LOCKSTAT_PROFILE_ENABLED(rw__release) || \ 121 !_rw_write_unlock_fetch((rw), &_v))) \ 122 _rw_wunlock_hard((rw), _v, (file), (line)); \ 123 } while (0) 124 125 /* 126 * Function prototypes. Routines that start with _ are not part of the 127 * external API and should not be called directly. Wrapper macros should 128 * be used instead. 129 */ 130 void _rw_init_flags(volatile uintptr_t *c, const char *name, int opts); 131 void _rw_destroy(volatile uintptr_t *c); 132 void rw_sysinit(void *arg); 133 int _rw_wowned(const volatile uintptr_t *c); 134 void _rw_wlock_cookie(volatile uintptr_t *c, const char *file, int line); 135 int __rw_try_wlock_int(struct rwlock *rw LOCK_FILE_LINE_ARG_DEF); 136 int __rw_try_wlock(volatile uintptr_t *c, const char *file, int line); 137 void _rw_wunlock_cookie(volatile uintptr_t *c, const char *file, int line); 138 void __rw_rlock_int(struct rwlock *rw LOCK_FILE_LINE_ARG_DEF); 139 void __rw_rlock(volatile uintptr_t *c, const char *file, int line); 140 int __rw_try_rlock_int(struct rwlock *rw LOCK_FILE_LINE_ARG_DEF); 141 int __rw_try_rlock(volatile uintptr_t *c, const char *file, int line); 142 void _rw_runlock_cookie_int(struct rwlock *rw LOCK_FILE_LINE_ARG_DEF); 143 void _rw_runlock_cookie(volatile uintptr_t *c, const char *file, int line); 144 void __rw_wlock_hard(volatile uintptr_t *c, uintptr_t v 145 LOCK_FILE_LINE_ARG_DEF); 146 void __rw_wunlock_hard(volatile uintptr_t *c, uintptr_t v 147 LOCK_FILE_LINE_ARG_DEF); 148 int __rw_try_upgrade_int(struct rwlock *rw LOCK_FILE_LINE_ARG_DEF); 149 int __rw_try_upgrade(volatile uintptr_t *c, const char *file, int line); 150 void __rw_downgrade_int(struct rwlock *rw LOCK_FILE_LINE_ARG_DEF); 151 void __rw_downgrade(volatile uintptr_t *c, const char *file, int line); 152 #if defined(INVARIANTS) || defined(INVARIANT_SUPPORT) 153 void __rw_assert(const volatile uintptr_t *c, int what, const char *file, 154 int line); 155 #endif 156 157 /* 158 * Top-level macros to provide lock cookie once the actual rwlock is passed. 159 * They will also prevent passing a malformed object to the rwlock KPI by 160 * failing compilation as the rw_lock reserved member will not be found. 161 */ 162 #define rw_init(rw, n) \ 163 _rw_init_flags(&(rw)->rw_lock, n, 0) 164 #define rw_init_flags(rw, n, o) \ 165 _rw_init_flags(&(rw)->rw_lock, n, o) 166 #define rw_destroy(rw) \ 167 _rw_destroy(&(rw)->rw_lock) 168 #define rw_wowned(rw) \ 169 _rw_wowned(&(rw)->rw_lock) 170 #define _rw_wlock(rw, f, l) \ 171 _rw_wlock_cookie(&(rw)->rw_lock, f, l) 172 #define _rw_try_wlock(rw, f, l) \ 173 __rw_try_wlock(&(rw)->rw_lock, f, l) 174 #define _rw_wunlock(rw, f, l) \ 175 _rw_wunlock_cookie(&(rw)->rw_lock, f, l) 176 #define _rw_try_rlock(rw, f, l) \ 177 __rw_try_rlock(&(rw)->rw_lock, f, l) 178 #if LOCK_DEBUG > 0 179 #define _rw_rlock(rw, f, l) \ 180 __rw_rlock(&(rw)->rw_lock, f, l) 181 #define _rw_runlock(rw, f, l) \ 182 _rw_runlock_cookie(&(rw)->rw_lock, f, l) 183 #else 184 #define _rw_rlock(rw, f, l) \ 185 __rw_rlock_int((struct rwlock *)rw) 186 #define _rw_runlock(rw, f, l) \ 187 _rw_runlock_cookie_int((struct rwlock *)rw) 188 #endif 189 #if LOCK_DEBUG > 0 190 #define _rw_wlock_hard(rw, v, f, l) \ 191 __rw_wlock_hard(&(rw)->rw_lock, v, f, l) 192 #define _rw_wunlock_hard(rw, v, f, l) \ 193 __rw_wunlock_hard(&(rw)->rw_lock, v, f, l) 194 #define _rw_try_upgrade(rw, f, l) \ 195 __rw_try_upgrade(&(rw)->rw_lock, f, l) 196 #define _rw_downgrade(rw, f, l) \ 197 __rw_downgrade(&(rw)->rw_lock, f, l) 198 #else 199 #define _rw_wlock_hard(rw, v, f, l) \ 200 __rw_wlock_hard(&(rw)->rw_lock, v) 201 #define _rw_wunlock_hard(rw, v, f, l) \ 202 __rw_wunlock_hard(&(rw)->rw_lock, v) 203 #define _rw_try_upgrade(rw, f, l) \ 204 __rw_try_upgrade_int(rw) 205 #define _rw_downgrade(rw, f, l) \ 206 __rw_downgrade_int(rw) 207 #endif 208 #if defined(INVARIANTS) || defined(INVARIANT_SUPPORT) 209 #define _rw_assert(rw, w, f, l) \ 210 __rw_assert(&(rw)->rw_lock, w, f, l) 211 #endif 212 213 214 /* 215 * Public interface for lock operations. 216 */ 217 218 #ifndef LOCK_DEBUG 219 #error LOCK_DEBUG not defined, include <sys/lock.h> before <sys/rwlock.h> 220 #endif 221 #if LOCK_DEBUG > 0 || defined(RWLOCK_NOINLINE) 222 #define rw_wlock(rw) _rw_wlock((rw), LOCK_FILE, LOCK_LINE) 223 #define rw_wunlock(rw) _rw_wunlock((rw), LOCK_FILE, LOCK_LINE) 224 #else 225 #define rw_wlock(rw) \ 226 __rw_wlock((rw), curthread, LOCK_FILE, LOCK_LINE) 227 #define rw_wunlock(rw) \ 228 __rw_wunlock((rw), curthread, LOCK_FILE, LOCK_LINE) 229 #endif 230 #define rw_rlock(rw) _rw_rlock((rw), LOCK_FILE, LOCK_LINE) 231 #define rw_runlock(rw) _rw_runlock((rw), LOCK_FILE, LOCK_LINE) 232 #define rw_try_rlock(rw) _rw_try_rlock((rw), LOCK_FILE, LOCK_LINE) 233 #define rw_try_upgrade(rw) _rw_try_upgrade((rw), LOCK_FILE, LOCK_LINE) 234 #define rw_try_wlock(rw) _rw_try_wlock((rw), LOCK_FILE, LOCK_LINE) 235 #define rw_downgrade(rw) _rw_downgrade((rw), LOCK_FILE, LOCK_LINE) 236 #define rw_unlock(rw) do { \ 237 if (rw_wowned(rw)) \ 238 rw_wunlock(rw); \ 239 else \ 240 rw_runlock(rw); \ 241 } while (0) 242 #define rw_sleep(chan, rw, pri, wmesg, timo) \ 243 _sleep((chan), &(rw)->lock_object, (pri), (wmesg), \ 244 tick_sbt * (timo), 0, C_HARDCLOCK) 245 246 #define rw_initialized(rw) lock_initialized(&(rw)->lock_object) 247 248 struct rw_args { 249 void *ra_rw; 250 const char *ra_desc; 251 int ra_flags; 252 }; 253 254 #define RW_SYSINIT_FLAGS(name, rw, desc, flags) \ 255 static struct rw_args name##_args = { \ 256 (rw), \ 257 (desc), \ 258 (flags), \ 259 }; \ 260 SYSINIT(name##_rw_sysinit, SI_SUB_LOCK, SI_ORDER_MIDDLE, \ 261 rw_sysinit, &name##_args); \ 262 SYSUNINIT(name##_rw_sysuninit, SI_SUB_LOCK, SI_ORDER_MIDDLE, \ 263 _rw_destroy, __DEVOLATILE(void *, &(rw)->rw_lock)) 264 265 #define RW_SYSINIT(name, rw, desc) RW_SYSINIT_FLAGS(name, rw, desc, 0) 266 267 /* 268 * Options passed to rw_init_flags(). 269 */ 270 #define RW_DUPOK 0x01 271 #define RW_NOPROFILE 0x02 272 #define RW_NOWITNESS 0x04 273 #define RW_QUIET 0x08 274 #define RW_RECURSE 0x10 275 #define RW_NEW 0x20 276 277 /* 278 * The INVARIANTS-enabled rw_assert() functionality. 279 * 280 * The constants need to be defined for INVARIANT_SUPPORT infrastructure 281 * support as _rw_assert() itself uses them and the latter implies that 282 * _rw_assert() must build. 283 */ 284 #if defined(INVARIANTS) || defined(INVARIANT_SUPPORT) 285 #define RA_LOCKED LA_LOCKED 286 #define RA_RLOCKED LA_SLOCKED 287 #define RA_WLOCKED LA_XLOCKED 288 #define RA_UNLOCKED LA_UNLOCKED 289 #define RA_RECURSED LA_RECURSED 290 #define RA_NOTRECURSED LA_NOTRECURSED 291 #endif 292 293 #ifdef INVARIANTS 294 #define rw_assert(rw, what) _rw_assert((rw), (what), LOCK_FILE, LOCK_LINE) 295 #else 296 #define rw_assert(rw, what) 297 #endif 298 299 #endif /* _KERNEL */ 300 #endif /* !_SYS_RWLOCK_H_ */ 301