sys/sys/rwlock.h

   1 /*-
   2  * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
   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  * $FreeBSD$
  28  */
  29
  30 #ifndef _SYS_RWLOCK_H_
  31 #define _SYS_RWLOCK_H_
  32
  33 #include <sys/_lock.h>
  34 #include <sys/_rwlock.h>
  35 #include <sys/lock_profile.h>
  36 #include <sys/lockstat.h>
  37
  38 #ifdef _KERNEL
  39 #include <sys/pcpu.h>
  40 #include <machine/atomic.h>
  41 #endif
  42
  43 /*
  44  * The rw_lock field consists of several fields.  The low bit indicates
  45  * if the lock is locked with a read (shared) or write (exclusive) lock.
  46  * A value of 0 indicates a write lock, and a value of 1 indicates a read
  47  * lock.  Bit 1 is a boolean indicating if there are any threads waiting
  48  * for a read lock.  Bit 2 is a boolean indicating if there are any threads
  49  * waiting for a write lock.  The rest of the variable's definition is
  50  * dependent on the value of the first bit.  For a write lock, it is a
  51  * pointer to the thread holding the lock, similar to the mtx_lock field of
  52  * mutexes.  For read locks, it is a count of read locks that are held.
  53  *
  54  * When the lock is not locked by any thread, it is encoded as a read lock
  55  * with zero waiters.
  56  */
  57
  58 #define RW_LOCK_READ            0x01
  59 #define RW_LOCK_READ_WAITERS    0x02
  60 #define RW_LOCK_WRITE_WAITERS   0x04
  61 #define RW_LOCK_WRITE_SPINNER   0x08
  62 #define RW_LOCK_WRITER_RECURSED 0x10
  63 #define RW_LOCK_FLAGMASK                                                \
  64         (RW_LOCK_READ | RW_LOCK_READ_WAITERS | RW_LOCK_WRITE_WAITERS |  \
  65         RW_LOCK_WRITE_SPINNER | RW_LOCK_WRITER_RECURSED)
  66 #define RW_LOCK_WAITERS         (RW_LOCK_READ_WAITERS | RW_LOCK_WRITE_WAITERS)
  67
  68 #define RW_OWNER(x)             ((x) & ~RW_LOCK_FLAGMASK)
  69 #define RW_READERS_SHIFT        5
  70 #define RW_READERS(x)           (RW_OWNER((x)) >> RW_READERS_SHIFT)
  71 #define RW_READERS_LOCK(x)      ((x) << RW_READERS_SHIFT | RW_LOCK_READ)
  72 #define RW_ONE_READER           (1 << RW_READERS_SHIFT)
  73
  74 #define RW_UNLOCKED             RW_READERS_LOCK(0)
  75 #define RW_DESTROYED            (RW_LOCK_READ_WAITERS | RW_LOCK_WRITE_WAITERS)
  76
  77 #ifdef _KERNEL
  78
  79 #define rw_recurse      lock_object.lo_data
  80
  81 #define RW_READ_VALUE(x)        ((x)->rw_lock)
  82
  83 /* Very simple operations on rw_lock. */
  84
  85 /* Try to obtain a write lock once. */
  86 #define _rw_write_lock(rw, tid)                                         \
  87         atomic_cmpset_acq_ptr(&(rw)->rw_lock, RW_UNLOCKED, (tid))
  88
  89 #define _rw_write_lock_fetch(rw, vp, tid)                               \
  90         atomic_fcmpset_acq_ptr(&(rw)->rw_lock, vp, (tid))
  91
  92 /* Release a write lock quickly if there are no waiters. */
  93 #define _rw_write_unlock(rw, tid)                                       \
  94         atomic_cmpset_rel_ptr(&(rw)->rw_lock, (tid), RW_UNLOCKED)
  95
  96 #define _rw_write_unlock_fetch(rw, tid)                                 \
  97         atomic_fcmpset_rel_ptr(&(rw)->rw_lock, (tid), RW_UNLOCKED)
  98
  99 /*
 100  * Full lock operations that are suitable to be inlined in non-debug
 101  * kernels.  If the lock cannot be acquired or released trivially then
 102  * the work is deferred to another function.
 103  */
 104
 105 /* Acquire a write lock. */
 106 #define __rw_wlock(rw, tid, file, line) do {                            \
 107         uintptr_t _tid = (uintptr_t)(tid);                              \
 108         uintptr_t _v = RW_UNLOCKED;                                     \
 109                                                                         \
 110         if (__predict_false(LOCKSTAT_PROFILE_ENABLED(rw__acquire) ||    \
 111             !_rw_write_lock_fetch((rw), &_v, _tid)))                    \
 112                 _rw_wlock_hard((rw), _v, (file), (line));               \
 113 } while (0)
 114
 115 /* Release a write lock. */
 116 #define __rw_wunlock(rw, tid, file, line) do {                          \
 117         uintptr_t _v = (uintptr_t)(tid);                                \
 118                                                                         \
 119         if (__predict_false(LOCKSTAT_PROFILE_ENABLED(rw__release) ||    \
 120             !_rw_write_unlock_fetch((rw), &_v)))                        \
 121                 _rw_wunlock_hard((rw), _v, (file), (line));             \
 122 } while (0)
 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)   do {                                            \
 235         if (rw_wowned(rw))                                              \
 236                 rw_wunlock(rw);                                         \
 237         else                                                            \
 238                 rw_runlock(rw);                                         \
 239 } while (0)
 240 #define rw_sleep(chan, rw, pri, wmesg, timo)                            \
 241         _sleep((chan), &(rw)->lock_object, (pri), (wmesg),              \
 242             tick_sbt * (timo), 0, C_HARDCLOCK)
 243
 244 #define rw_initialized(rw)      lock_initialized(&(rw)->lock_object)
 245
 246 struct rw_args {
 247         void            *ra_rw;
 248         const char      *ra_desc;
 249         int             ra_flags;
 250 };
 251
 252 #define RW_SYSINIT_FLAGS(name, rw, desc, flags)                         \
 253         static struct rw_args name##_args = {                           \
 254                 (rw),                                                   \
 255                 (desc),                                                 \
 256                 (flags),                                                \
 257         };                                                              \
 258         SYSINIT(name##_rw_sysinit, SI_SUB_LOCK, SI_ORDER_MIDDLE,        \
 259             rw_sysinit, &name##_args);                                  \
 260         SYSUNINIT(name##_rw_sysuninit, SI_SUB_LOCK, SI_ORDER_MIDDLE,    \
 261             _rw_destroy, __DEVOLATILE(void *, &(rw)->rw_lock))
 262
 263 #define RW_SYSINIT(name, rw, desc)      RW_SYSINIT_FLAGS(name, rw, desc, 0)
 264
 265 /*
 266  * Options passed to rw_init_flags().
 267  */
 268 #define RW_DUPOK        0x01
 269 #define RW_NOPROFILE    0x02
 270 #define RW_NOWITNESS    0x04
 271 #define RW_QUIET        0x08
 272 #define RW_RECURSE      0x10
 273 #define RW_NEW          0x20
 274
 275 /*
 276  * The INVARIANTS-enabled rw_assert() functionality.
 277  *
 278  * The constants need to be defined for INVARIANT_SUPPORT infrastructure
 279  * support as _rw_assert() itself uses them and the latter implies that
 280  * _rw_assert() must build.
 281  */
 282 #if defined(INVARIANTS) || defined(INVARIANT_SUPPORT)
 283 #define RA_LOCKED               LA_LOCKED
 284 #define RA_RLOCKED              LA_SLOCKED
 285 #define RA_WLOCKED              LA_XLOCKED
 286 #define RA_UNLOCKED             LA_UNLOCKED
 287 #define RA_RECURSED             LA_RECURSED
 288 #define RA_NOTRECURSED          LA_NOTRECURSED
 289 #endif
 290
 291 #ifdef INVARIANTS
 292 #define rw_assert(rw, what)     _rw_assert((rw), (what), LOCK_FILE, LOCK_LINE)
 293 #else
 294 #define rw_assert(rw, what)
 295 #endif
 296
 297 #endif /* _KERNEL */
 298 #endif /* !_SYS_RWLOCK_H_ */