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/10/sys/sys/rwlock.h 323870 2017-09-21 19:24:11Z marius $ 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)->rw_lock != RW_UNLOCKED || !_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 void _rw_init_flags(volatile uintptr_t *c, const char *name, int opts); 122 void _rw_destroy(volatile uintptr_t *c); 123 void rw_sysinit(void *arg); 124 void rw_sysinit_flags(void *arg); 125 int _rw_wowned(const volatile uintptr_t *c); 126 void _rw_wlock_cookie(volatile uintptr_t *c, const char *file, int line); 127 int __rw_try_wlock(volatile uintptr_t *c, const char *file, int line); 128 void _rw_wunlock_cookie(volatile uintptr_t *c, const char *file, int line); 129 void __rw_rlock(volatile uintptr_t *c, const char *file, int line); 130 int __rw_try_rlock(volatile uintptr_t *c, const char *file, int line); 131 void _rw_runlock_cookie(volatile uintptr_t *c, const char *file, int line); 132 void __rw_wlock_hard(volatile uintptr_t *c, uintptr_t tid, const char *file, 133 int line); 134 void __rw_wunlock_hard(volatile uintptr_t *c, uintptr_t tid, 135 const char *file, int line); 136 int __rw_try_upgrade(volatile uintptr_t *c, const char *file, int line); 137 void __rw_downgrade(volatile uintptr_t *c, const char *file, int line); 138 #if defined(INVARIANTS) || defined(INVARIANT_SUPPORT) 139 void __rw_assert(const volatile uintptr_t *c, int what, const char *file, 140 int line); 141 #endif 142 143 /* 144 * Top-level macros to provide lock cookie once the actual rwlock is passed. 145 * They will also prevent passing a malformed object to the rwlock KPI by 146 * failing compilation as the rw_lock reserved member will not be found. 147 */ 148 #define rw_init(rw, n) \ 149 _rw_init_flags(&(rw)->rw_lock, n, 0) 150 #define rw_init_flags(rw, n, o) \ 151 _rw_init_flags(&(rw)->rw_lock, n, o) 152 #define rw_destroy(rw) \ 153 _rw_destroy(&(rw)->rw_lock) 154 #define rw_wowned(rw) \ 155 _rw_wowned(&(rw)->rw_lock) 156 #define _rw_wlock(rw, f, l) \ 157 _rw_wlock_cookie(&(rw)->rw_lock, f, l) 158 #define _rw_try_wlock(rw, f, l) \ 159 __rw_try_wlock(&(rw)->rw_lock, f, l) 160 #define _rw_wunlock(rw, f, l) \ 161 _rw_wunlock_cookie(&(rw)->rw_lock, f, l) 162 #define _rw_rlock(rw, f, l) \ 163 __rw_rlock(&(rw)->rw_lock, f, l) 164 #define _rw_try_rlock(rw, f, l) \ 165 __rw_try_rlock(&(rw)->rw_lock, f, l) 166 #define _rw_runlock(rw, f, l) \ 167 _rw_runlock_cookie(&(rw)->rw_lock, f, l) 168 #define _rw_wlock_hard(rw, t, f, l) \ 169 __rw_wlock_hard(&(rw)->rw_lock, t, f, l) 170 #define _rw_wunlock_hard(rw, t, f, l) \ 171 __rw_wunlock_hard(&(rw)->rw_lock, t, f, l) 172 #define _rw_try_upgrade(rw, f, l) \ 173 __rw_try_upgrade(&(rw)->rw_lock, f, l) 174 #define _rw_downgrade(rw, f, l) \ 175 __rw_downgrade(&(rw)->rw_lock, f, l) 176 #if defined(INVARIANTS) || defined(INVARIANT_SUPPORT) 177 #define _rw_assert(rw, w, f, l) \ 178 __rw_assert(&(rw)->rw_lock, w, f, l) 179 #endif 180 181 182 /* 183 * Public interface for lock operations. 184 */ 185 186 #ifndef LOCK_DEBUG 187 #error LOCK_DEBUG not defined, include <sys/lock.h> before <sys/rwlock.h> 188 #endif 189 #if LOCK_DEBUG > 0 || defined(RWLOCK_NOINLINE) 190 #define rw_wlock(rw) _rw_wlock((rw), LOCK_FILE, LOCK_LINE) 191 #define rw_wunlock(rw) _rw_wunlock((rw), LOCK_FILE, LOCK_LINE) 192 #else 193 #define rw_wlock(rw) \ 194 __rw_wlock((rw), curthread, LOCK_FILE, LOCK_LINE) 195 #define rw_wunlock(rw) \ 196 __rw_wunlock((rw), curthread, LOCK_FILE, LOCK_LINE) 197 #endif 198 #define rw_rlock(rw) _rw_rlock((rw), LOCK_FILE, LOCK_LINE) 199 #define rw_runlock(rw) _rw_runlock((rw), LOCK_FILE, LOCK_LINE) 200 #define rw_try_rlock(rw) _rw_try_rlock((rw), LOCK_FILE, LOCK_LINE) 201 #define rw_try_upgrade(rw) _rw_try_upgrade((rw), LOCK_FILE, LOCK_LINE) 202 #define rw_try_wlock(rw) _rw_try_wlock((rw), LOCK_FILE, LOCK_LINE) 203 #define rw_downgrade(rw) _rw_downgrade((rw), LOCK_FILE, LOCK_LINE) 204 #define rw_unlock(rw) do { \ 205 if (rw_wowned(rw)) \ 206 rw_wunlock(rw); \ 207 else \ 208 rw_runlock(rw); \ 209 } while (0) 210 #define rw_sleep(chan, rw, pri, wmesg, timo) \ 211 _sleep((chan), &(rw)->lock_object, (pri), (wmesg), \ 212 tick_sbt * (timo), 0, C_HARDCLOCK) 213 214 #define rw_initialized(rw) lock_initalized(&(rw)->lock_object) 215 216 struct rw_args { 217 void *ra_rw; 218 const char *ra_desc; 219 }; 220 221 struct rw_args_flags { 222 void *ra_rw; 223 const char *ra_desc; 224 int ra_flags; 225 }; 226 227 #define RW_SYSINIT(name, rw, desc) \ 228 static struct rw_args name##_args = { \ 229 (rw), \ 230 (desc), \ 231 }; \ 232 SYSINIT(name##_rw_sysinit, SI_SUB_LOCK, SI_ORDER_MIDDLE, \ 233 rw_sysinit, &name##_args); \ 234 SYSUNINIT(name##_rw_sysuninit, SI_SUB_LOCK, SI_ORDER_MIDDLE, \ 235 _rw_destroy, __DEVOLATILE(void *, &(rw)->rw_lock)) 236 237 238 #define RW_SYSINIT_FLAGS(name, rw, desc, flags) \ 239 static struct rw_args_flags name##_args = { \ 240 (rw), \ 241 (desc), \ 242 (flags), \ 243 }; \ 244 SYSINIT(name##_rw_sysinit, SI_SUB_LOCK, SI_ORDER_MIDDLE, \ 245 rw_sysinit_flags, &name##_args); \ 246 SYSUNINIT(name##_rw_sysuninit, SI_SUB_LOCK, SI_ORDER_MIDDLE, \ 247 _rw_destroy, __DEVOLATILE(void *, &(rw)->rw_lock)) 248 249 /* 250 * Options passed to rw_init_flags(). 251 */ 252 #define RW_DUPOK 0x01 253 #define RW_NOPROFILE 0x02 254 #define RW_NOWITNESS 0x04 255 #define RW_QUIET 0x08 256 #define RW_RECURSE 0x10 257 #define RW_NEW 0x20 258 259 /* 260 * The INVARIANTS-enabled rw_assert() functionality. 261 * 262 * The constants need to be defined for INVARIANT_SUPPORT infrastructure 263 * support as _rw_assert() itself uses them and the latter implies that 264 * _rw_assert() must build. 265 */ 266 #if defined(INVARIANTS) || defined(INVARIANT_SUPPORT) 267 #define RA_LOCKED LA_LOCKED 268 #define RA_RLOCKED LA_SLOCKED 269 #define RA_WLOCKED LA_XLOCKED 270 #define RA_UNLOCKED LA_UNLOCKED 271 #define RA_RECURSED LA_RECURSED 272 #define RA_NOTRECURSED LA_NOTRECURSED 273 #endif 274 275 #ifdef INVARIANTS 276 #define rw_assert(rw, what) _rw_assert((rw), (what), LOCK_FILE, LOCK_LINE) 277 #else 278 #define rw_assert(rw, what) 279 #endif 280 281 #endif /* _KERNEL */ 282 #endif /* !_SYS_RWLOCK_H_ */ 283