sys/sys/rwlock.h

   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  * $FreeBSD$
  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_WRITER_RECURSED 0x10
  62 #define RW_LOCK_FLAGMASK                                                \
  63         (RW_LOCK_READ | RW_LOCK_READ_WAITERS | RW_LOCK_WRITE_WAITERS |  \
  64         RW_LOCK_WRITE_SPINNER | RW_LOCK_WRITER_RECURSED)
  65 #define RW_LOCK_WAITERS         (RW_LOCK_READ_WAITERS | RW_LOCK_WRITE_WAITERS)
  66
  67 #define RW_OWNER(x)             ((x) & ~RW_LOCK_FLAGMASK)
  68 #define RW_READERS_SHIFT        5
  69 #define RW_READERS(x)           (RW_OWNER((x)) >> RW_READERS_SHIFT)
  70 #define RW_READERS_LOCK(x)      ((x) << RW_READERS_SHIFT | RW_LOCK_READ)
  71 #define RW_ONE_READER           (1 << RW_READERS_SHIFT)
  72
  73 #define RW_UNLOCKED             RW_READERS_LOCK(0)
  74 #define RW_DESTROYED            (RW_LOCK_READ_WAITERS | RW_LOCK_WRITE_WAITERS)
  75
  76 #ifdef _KERNEL
  77
  78 #define rw_recurse      lock_object.lo_data
  79
  80 #define RW_READ_VALUE(x)        ((x)->rw_lock)
  81
  82 /* Very simple operations on rw_lock. */
  83
  84 /* Try to obtain a write lock once. */
  85 #define _rw_write_lock(rw, tid)                                         \
  86         atomic_cmpset_acq_ptr(&(rw)->rw_lock, RW_UNLOCKED, (tid))
  87
  88 #define _rw_write_lock_fetch(rw, vp, tid)                               \
  89         atomic_fcmpset_acq_ptr(&(rw)->rw_lock, vp, (tid))
  90
  91 /* Release a write lock quickly if there are no waiters. */
  92 #define _rw_write_unlock(rw, tid)                                       \
  93         atomic_cmpset_rel_ptr(&(rw)->rw_lock, (tid), RW_UNLOCKED)
  94
  95 #define _rw_write_unlock_fetch(rw, tid)                                 \
  96         atomic_fcmpset_rel_ptr(&(rw)->rw_lock, (tid), RW_UNLOCKED)
  97
  98 /*
  99  * Full lock operations that are suitable to be inlined in non-debug
 100  * kernels.  If the lock cannot be acquired or released trivially then
 101  * the work is deferred to another function.
 102  */
 103
 104 /* Acquire a write lock. */
 105 #define __rw_wlock(rw, tid, file, line) do {                            \
 106         uintptr_t _tid = (uintptr_t)(tid);                              \
 107         uintptr_t _v = RW_UNLOCKED;                                     \
 108                                                                         \
 109         if (__predict_false(LOCKSTAT_PROFILE_ENABLED(rw__acquire) ||    \
 110             !_rw_write_lock_fetch((rw), &_v, _tid)))                    \
 111                 _rw_wlock_hard((rw), _v, (file), (line));               \
 112 } while (0)
 113
 114 /* Release a write lock. */
 115 #define __rw_wunlock(rw, tid, file, line) do {                          \
 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 } while (0)
 122
 123 /*
 124  * Function prototypes.  Routines that start with _ are not part of the
 125  * external API and should not be called directly.  Wrapper macros should
 126  * be used instead.
 127  */
 128 void    _rw_init_flags(volatile uintptr_t *c, const char *name, int opts);
 129 void    _rw_destroy(volatile uintptr_t *c);
 130 void    rw_sysinit(void *arg);
 131 int     _rw_wowned(const volatile uintptr_t *c);
 132 void    _rw_wlock_cookie(volatile uintptr_t *c, const char *file, int line);
 133 int     __rw_try_wlock_int(struct rwlock *rw LOCK_FILE_LINE_ARG_DEF);
 134 int     __rw_try_wlock(volatile uintptr_t *c, const char *file, int line);
 135 void    _rw_wunlock_cookie(volatile uintptr_t *c, const char *file, int line);
 136 void    __rw_rlock_int(struct rwlock *rw LOCK_FILE_LINE_ARG_DEF);
 137 void    __rw_rlock(volatile uintptr_t *c, const char *file, int line);
 138 int     __rw_try_rlock_int(struct rwlock *rw LOCK_FILE_LINE_ARG_DEF);
 139 int     __rw_try_rlock(volatile uintptr_t *c, const char *file, int line);
 140 void    _rw_runlock_cookie_int(struct rwlock *rw LOCK_FILE_LINE_ARG_DEF);
 141 void    _rw_runlock_cookie(volatile uintptr_t *c, const char *file, int line);
 142 void    __rw_wlock_hard(volatile uintptr_t *c, uintptr_t v
 143             LOCK_FILE_LINE_ARG_DEF);
 144 void    __rw_wunlock_hard(volatile uintptr_t *c, uintptr_t v
 145             LOCK_FILE_LINE_ARG_DEF);
 146 int     __rw_try_upgrade_int(struct rwlock *rw LOCK_FILE_LINE_ARG_DEF);
 147 int     __rw_try_upgrade(volatile uintptr_t *c, const char *file, int line);
 148 void    __rw_downgrade_int(struct rwlock *rw LOCK_FILE_LINE_ARG_DEF);
 149 void    __rw_downgrade(volatile uintptr_t *c, const char *file, int line);
 150 #if defined(INVARIANTS) || defined(INVARIANT_SUPPORT)
 151 void    __rw_assert(const volatile uintptr_t *c, int what, const char *file,
 152             int line);
 153 #endif
 154
 155 /*
 156  * Top-level macros to provide lock cookie once the actual rwlock is passed.
 157  * They will also prevent passing a malformed object to the rwlock KPI by
 158  * failing compilation as the rw_lock reserved member will not be found.
 159  */
 160 #define rw_init(rw, n)                                                  \
 161         _rw_init_flags(&(rw)->rw_lock, n, 0)
 162 #define rw_init_flags(rw, n, o)                                         \
 163         _rw_init_flags(&(rw)->rw_lock, n, o)
 164 #define rw_destroy(rw)                                                  \
 165         _rw_destroy(&(rw)->rw_lock)
 166 #define rw_wowned(rw)                                                   \
 167         _rw_wowned(&(rw)->rw_lock)
 168 #define _rw_wlock(rw, f, l)                                             \
 169         _rw_wlock_cookie(&(rw)->rw_lock, f, l)
 170 #define _rw_try_wlock(rw, f, l)                                         \
 171         __rw_try_wlock(&(rw)->rw_lock, f, l)
 172 #define _rw_wunlock(rw, f, l)                                           \
 173         _rw_wunlock_cookie(&(rw)->rw_lock, f, l)
 174 #define _rw_try_rlock(rw, f, l)                                         \
 175         __rw_try_rlock(&(rw)->rw_lock, f, l)
 176 #if LOCK_DEBUG > 0
 177 #define _rw_rlock(rw, f, l)                                             \
 178         __rw_rlock(&(rw)->rw_lock, f, l)
 179 #define _rw_runlock(rw, f, l)                                           \
 180         _rw_runlock_cookie(&(rw)->rw_lock, f, l)
 181 #else
 182 #define _rw_rlock(rw, f, l)                                             \
 183         __rw_rlock_int((struct rwlock *)rw)
 184 #define _rw_runlock(rw, f, l)                                           \
 185         _rw_runlock_cookie_int((struct rwlock *)rw)
 186 #endif
 187 #if LOCK_DEBUG > 0
 188 #define _rw_wlock_hard(rw, v, f, l)                                     \
 189         __rw_wlock_hard(&(rw)->rw_lock, v, f, l)
 190 #define _rw_wunlock_hard(rw, v, f, l)                                   \
 191         __rw_wunlock_hard(&(rw)->rw_lock, v, f, l)
 192 #define _rw_try_upgrade(rw, f, l)                                       \
 193         __rw_try_upgrade(&(rw)->rw_lock, f, l)
 194 #define _rw_downgrade(rw, f, l)                                         \
 195         __rw_downgrade(&(rw)->rw_lock, f, l)
 196 #else
 197 #define _rw_wlock_hard(rw, v, f, l)                                     \
 198         __rw_wlock_hard(&(rw)->rw_lock, v)
 199 #define _rw_wunlock_hard(rw, v, f, l)                                   \
 200         __rw_wunlock_hard(&(rw)->rw_lock, v)
 201 #define _rw_try_upgrade(rw, f, l)                                       \
 202         __rw_try_upgrade_int(rw)
 203 #define _rw_downgrade(rw, f, l)                                         \
 204         __rw_downgrade_int(rw)
 205 #endif
 206 #if defined(INVARIANTS) || defined(INVARIANT_SUPPORT)
 207 #define _rw_assert(rw, w, f, l)                                         \
 208         __rw_assert(&(rw)->rw_lock, w, f, l)
 209 #endif
 210
 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_ */