1/*- 2 * Copyright (c) 2006 John Baldwin <jhb@FreeBSD.org> 3 * 4 * Redistribution and use in source and binary forms, with or without 5 * modification, are permitted provided that the following conditions 6 * are met: 7 * 1. Redistributions of source code must retain the above copyright 8 * notice, this list of conditions and the following disclaimer. 9 * 2. Redistributions in binary form must reproduce the above copyright 10 * notice, this list of conditions and the following disclaimer in the 11 * documentation and/or other materials provided with the distribution. 12 * 13 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 14 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 15 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 16 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 17 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 18 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 19 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 20 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 21 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 22 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 23 * SUCH DAMAGE. 24 * 25 * $FreeBSD: stable/11/sys/sys/rwlock.h 367457 2020-11-07 18:10:59Z dim $ 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) do { \ 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} while (0) 112 113/* Release a write lock. */ 114#define __rw_wunlock(rw, tid, file, line) do { \ 115 uintptr_t _v = (uintptr_t)(tid); \ 116 \ 117 if (__predict_false(LOCKSTAT_PROFILE_ENABLED(rw__release) || \ 118 !_rw_write_unlock_fetch((rw), &_v))) \ 119 _rw_wunlock_hard((rw), _v, (file), (line)); \ 120} while (0) 121 122/* 123 * Function prototypes. Routines that start with _ are not part of the 124 * external API and should not be called directly. Wrapper macros should 125 * be used instead. 126 */ 127void _rw_init_flags(volatile uintptr_t *c, const char *name, int opts); 128void _rw_destroy(volatile uintptr_t *c); 129void rw_sysinit(void *arg); 130int _rw_wowned(const volatile uintptr_t *c); 131void _rw_wlock_cookie(volatile uintptr_t *c, const char *file, int line); 132int __rw_try_wlock_int(struct rwlock *rw LOCK_FILE_LINE_ARG_DEF); 133int __rw_try_wlock(volatile uintptr_t *c, const char *file, int line); 134void _rw_wunlock_cookie(volatile uintptr_t *c, const char *file, int line); 135void __rw_rlock_int(struct rwlock *rw LOCK_FILE_LINE_ARG_DEF); 136void __rw_rlock(volatile uintptr_t *c, const char *file, int line); 137int __rw_try_rlock_int(struct rwlock *rw LOCK_FILE_LINE_ARG_DEF); 138int __rw_try_rlock(volatile uintptr_t *c, const char *file, int line); 139void _rw_runlock_cookie_int(struct rwlock *rw LOCK_FILE_LINE_ARG_DEF); 140void _rw_runlock_cookie(volatile uintptr_t *c, const char *file, int line); 141void __rw_wlock_hard(volatile uintptr_t *c, uintptr_t v 142 LOCK_FILE_LINE_ARG_DEF); 143void __rw_wunlock_hard(volatile uintptr_t *c, uintptr_t v 144 LOCK_FILE_LINE_ARG_DEF); 145int __rw_try_upgrade_int(struct rwlock *rw LOCK_FILE_LINE_ARG_DEF); 146int __rw_try_upgrade(volatile uintptr_t *c, const char *file, int line); 147void __rw_downgrade_int(struct rwlock *rw LOCK_FILE_LINE_ARG_DEF); 148void __rw_downgrade(volatile uintptr_t *c, const char *file, int line); 149#if defined(INVARIANTS) || defined(INVARIANT_SUPPORT) 150void __rw_assert(const volatile uintptr_t *c, int what, const char *file, 151 int line); 152#endif 153 154/* 155 * Top-level macros to provide lock cookie once the actual rwlock is passed. 156 * They will also prevent passing a malformed object to the rwlock KPI by 157 * failing compilation as the rw_lock reserved member will not be found. 158 */ 159#define rw_init(rw, n) \ 160 _rw_init_flags(&(rw)->rw_lock, n, 0) 161#define rw_init_flags(rw, n, o) \ 162 _rw_init_flags(&(rw)->rw_lock, n, o) 163#define rw_destroy(rw) \ 164 _rw_destroy(&(rw)->rw_lock) 165#define rw_wowned(rw) \ 166 _rw_wowned(&(rw)->rw_lock) 167#define _rw_wlock(rw, f, l) \ 168 _rw_wlock_cookie(&(rw)->rw_lock, f, l) 169#define _rw_try_wlock(rw, f, l) \ 170 __rw_try_wlock(&(rw)->rw_lock, f, l) 171#define _rw_wunlock(rw, f, l) \ 172 _rw_wunlock_cookie(&(rw)->rw_lock, f, l) 173#define _rw_try_rlock(rw, f, l) \ 174 __rw_try_rlock(&(rw)->rw_lock, f, l) 175#if LOCK_DEBUG > 0 176#define _rw_rlock(rw, f, l) \ 177 __rw_rlock(&(rw)->rw_lock, f, l) 178#define _rw_runlock(rw, f, l) \ 179 _rw_runlock_cookie(&(rw)->rw_lock, f, l) 180#else 181#define _rw_rlock(rw, f, l) \ 182 __rw_rlock_int((struct rwlock *)rw) 183#define _rw_runlock(rw, f, l) \ 184 _rw_runlock_cookie_int((struct rwlock *)rw) 185#endif 186#if LOCK_DEBUG > 0 187#define _rw_wlock_hard(rw, v, f, l) \ 188 __rw_wlock_hard(&(rw)->rw_lock, v, f, l) 189#define _rw_wunlock_hard(rw, v, f, l) \ 190 __rw_wunlock_hard(&(rw)->rw_lock, v, f, l) 191#define _rw_try_upgrade(rw, f, l) \ 192 __rw_try_upgrade(&(rw)->rw_lock, f, l) 193#define _rw_downgrade(rw, f, l) \ 194 __rw_downgrade(&(rw)->rw_lock, f, l) 195#else 196#define _rw_wlock_hard(rw, v, f, l) \ 197 __rw_wlock_hard(&(rw)->rw_lock, v) 198#define _rw_wunlock_hard(rw, v, f, l) \ 199 __rw_wunlock_hard(&(rw)->rw_lock, v) 200#define _rw_try_upgrade(rw, f, l) \ 201 __rw_try_upgrade_int(rw) 202#define _rw_downgrade(rw, f, l) \ 203 __rw_downgrade_int(rw) 204#endif 205#if defined(INVARIANTS) || defined(INVARIANT_SUPPORT) 206#define _rw_assert(rw, w, f, l) \ 207 __rw_assert(&(rw)->rw_lock, w, f, l) 208#endif 209 210 211/* 212 * Public interface for lock operations. 213 */ 214 215#ifndef LOCK_DEBUG 216#error LOCK_DEBUG not defined, include <sys/lock.h> before <sys/rwlock.h> 217#endif 218#if LOCK_DEBUG > 0 || defined(RWLOCK_NOINLINE) 219#define rw_wlock(rw) _rw_wlock((rw), LOCK_FILE, LOCK_LINE) 220#define rw_wunlock(rw) _rw_wunlock((rw), LOCK_FILE, LOCK_LINE) 221#else 222#define rw_wlock(rw) \ 223 __rw_wlock((rw), curthread, LOCK_FILE, LOCK_LINE) 224#define rw_wunlock(rw) \ 225 __rw_wunlock((rw), curthread, LOCK_FILE, LOCK_LINE) 226#endif 227#define rw_rlock(rw) _rw_rlock((rw), LOCK_FILE, LOCK_LINE) 228#define rw_runlock(rw) _rw_runlock((rw), LOCK_FILE, LOCK_LINE) 229#define rw_try_rlock(rw) _rw_try_rlock((rw), LOCK_FILE, LOCK_LINE) 230#define rw_try_upgrade(rw) _rw_try_upgrade((rw), LOCK_FILE, LOCK_LINE) 231#define rw_try_wlock(rw) _rw_try_wlock((rw), LOCK_FILE, LOCK_LINE) 232#define rw_downgrade(rw) _rw_downgrade((rw), LOCK_FILE, LOCK_LINE) 233#define rw_unlock(rw) do { \ 234 if (rw_wowned(rw)) \ 235 rw_wunlock(rw); \ 236 else \ 237 rw_runlock(rw); \ 238} while (0) 239#define rw_sleep(chan, rw, pri, wmesg, timo) \ 240 _sleep((chan), &(rw)->lock_object, (pri), (wmesg), \ 241 tick_sbt * (timo), 0, C_HARDCLOCK) 242 243#define rw_initialized(rw) lock_initialized(&(rw)->lock_object) 244 245struct rw_args { 246 void *ra_rw; 247 const char *ra_desc; 248 int ra_flags; 249}; 250 251#define RW_SYSINIT_FLAGS(name, rw, desc, flags) \ 252 static struct rw_args name##_args = { \ 253 (rw), \ 254 (desc), \ 255 (flags), \ 256 }; \ 257 SYSINIT(name##_rw_sysinit, SI_SUB_LOCK, SI_ORDER_MIDDLE, \ 258 rw_sysinit, &name##_args); \ 259 SYSUNINIT(name##_rw_sysuninit, SI_SUB_LOCK, SI_ORDER_MIDDLE, \ 260 _rw_destroy, __DEVOLATILE(void *, &(rw)->rw_lock)) 261 262#define RW_SYSINIT(name, rw, desc) RW_SYSINIT_FLAGS(name, rw, desc, 0) 263 264/* 265 * Options passed to rw_init_flags(). 266 */ 267#define RW_DUPOK 0x01 268#define RW_NOPROFILE 0x02 269#define RW_NOWITNESS 0x04 270#define RW_QUIET 0x08 271#define RW_RECURSE 0x10 272#define RW_NEW 0x20 273 274/* 275 * The INVARIANTS-enabled rw_assert() functionality. 276 * 277 * The constants need to be defined for INVARIANT_SUPPORT infrastructure 278 * support as _rw_assert() itself uses them and the latter implies that 279 * _rw_assert() must build. 280 */ 281#if defined(INVARIANTS) || defined(INVARIANT_SUPPORT) 282#define RA_LOCKED LA_LOCKED 283#define RA_RLOCKED LA_SLOCKED 284#define RA_WLOCKED LA_XLOCKED 285#define RA_UNLOCKED LA_UNLOCKED 286#define RA_RECURSED LA_RECURSED 287#define RA_NOTRECURSED LA_NOTRECURSED 288#endif 289 290#ifdef INVARIANTS 291#define rw_assert(rw, what) _rw_assert((rw), (what), LOCK_FILE, LOCK_LINE) 292#else 293#define rw_assert(rw, what) 294#endif 295 296#endif /* _KERNEL */ 297#endif /* !_SYS_RWLOCK_H_ */ 298