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) __extension__ ({                \
 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         (void)0; /* ensure void type for expression */                  \
 114 })
 115
 116 /* Release a write lock. */
 117 #define __rw_wunlock(rw, tid, file, line) __extension__ ({              \
 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         (void)0; /* ensure void type for expression */                  \
 124 })
 125
 126 /*
 127  * Function prototypes.  Routines that start with _ are not part of the
 128  * external API and should not be called directly.  Wrapper macros should
 129  * be used instead.
 130  */
 131 void    _rw_init_flags(volatile uintptr_t *c, const char *name, int opts);
 132 void    _rw_destroy(volatile uintptr_t *c);
 133 void    rw_sysinit(void *arg);
 134 int     _rw_wowned(const volatile uintptr_t *c);
 135 void    _rw_wlock_cookie(volatile uintptr_t *c, const char *file, int line);
 136 int     __rw_try_wlock_int(struct rwlock *rw LOCK_FILE_LINE_ARG_DEF);
 137 int     __rw_try_wlock(volatile uintptr_t *c, const char *file, int line);
 138 void    _rw_wunlock_cookie(volatile uintptr_t *c, const char *file, int line);
 139 void    __rw_rlock_int(struct rwlock *rw LOCK_FILE_LINE_ARG_DEF);
 140 void    __rw_rlock(volatile uintptr_t *c, const char *file, int line);
 141 int     __rw_try_rlock_int(struct rwlock *rw LOCK_FILE_LINE_ARG_DEF);
 142 int     __rw_try_rlock(volatile uintptr_t *c, const char *file, int line);
 143 void    _rw_runlock_cookie_int(struct rwlock *rw LOCK_FILE_LINE_ARG_DEF);
 144 void    _rw_runlock_cookie(volatile uintptr_t *c, const char *file, int line);
 145 void    __rw_wlock_hard(volatile uintptr_t *c, uintptr_t v
 146             LOCK_FILE_LINE_ARG_DEF);
 147 void    __rw_wunlock_hard(volatile uintptr_t *c, uintptr_t v
 148             LOCK_FILE_LINE_ARG_DEF);
 149 int     __rw_try_upgrade_int(struct rwlock *rw LOCK_FILE_LINE_ARG_DEF);
 150 int     __rw_try_upgrade(volatile uintptr_t *c, const char *file, int line);
 151 void    __rw_downgrade_int(struct rwlock *rw LOCK_FILE_LINE_ARG_DEF);
 152 void    __rw_downgrade(volatile uintptr_t *c, const char *file, int line);
 153 #if defined(INVARIANTS) || defined(INVARIANT_SUPPORT)
 154 void    __rw_assert(const volatile uintptr_t *c, int what, const char *file,
 155             int line);
 156 #endif
 157
 158 /*
 159  * Top-level macros to provide lock cookie once the actual rwlock is passed.
 160  * They will also prevent passing a malformed object to the rwlock KPI by
 161  * failing compilation as the rw_lock reserved member will not be found.
 162  */
 163 #define rw_init(rw, n)                                                  \
 164         _rw_init_flags(&(rw)->rw_lock, n, 0)
 165 #define rw_init_flags(rw, n, o)                                         \
 166         _rw_init_flags(&(rw)->rw_lock, n, o)
 167 #define rw_destroy(rw)                                                  \
 168         _rw_destroy(&(rw)->rw_lock)
 169 #define rw_wowned(rw)                                                   \
 170         _rw_wowned(&(rw)->rw_lock)
 171 #define _rw_wlock(rw, f, l)                                             \
 172         _rw_wlock_cookie(&(rw)->rw_lock, f, l)
 173 #define _rw_try_wlock(rw, f, l)                                         \
 174         __rw_try_wlock(&(rw)->rw_lock, f, l)
 175 #define _rw_wunlock(rw, f, l)                                           \
 176         _rw_wunlock_cookie(&(rw)->rw_lock, f, l)
 177 #define _rw_try_rlock(rw, f, l)                                         \
 178         __rw_try_rlock(&(rw)->rw_lock, f, l)
 179 #if LOCK_DEBUG > 0
 180 #define _rw_rlock(rw, f, l)                                             \
 181         __rw_rlock(&(rw)->rw_lock, f, l)
 182 #define _rw_runlock(rw, f, l)                                           \
 183         _rw_runlock_cookie(&(rw)->rw_lock, f, l)
 184 #else
 185 #define _rw_rlock(rw, f, l)                                             \
 186         __rw_rlock_int((struct rwlock *)rw)
 187 #define _rw_runlock(rw, f, l)                                           \
 188         _rw_runlock_cookie_int((struct rwlock *)rw)
 189 #endif
 190 #if LOCK_DEBUG > 0
 191 #define _rw_wlock_hard(rw, v, f, l)                                     \
 192         __rw_wlock_hard(&(rw)->rw_lock, v, f, l)
 193 #define _rw_wunlock_hard(rw, v, f, l)                                   \
 194         __rw_wunlock_hard(&(rw)->rw_lock, v, f, l)
 195 #define _rw_try_upgrade(rw, f, l)                                       \
 196         __rw_try_upgrade(&(rw)->rw_lock, f, l)
 197 #define _rw_downgrade(rw, f, l)                                         \
 198         __rw_downgrade(&(rw)->rw_lock, f, l)
 199 #else
 200 #define _rw_wlock_hard(rw, v, f, l)                                     \
 201         __rw_wlock_hard(&(rw)->rw_lock, v)
 202 #define _rw_wunlock_hard(rw, v, f, l)                                   \
 203         __rw_wunlock_hard(&(rw)->rw_lock, v)
 204 #define _rw_try_upgrade(rw, f, l)                                       \
 205         __rw_try_upgrade_int(rw)
 206 #define _rw_downgrade(rw, f, l)                                         \
 207         __rw_downgrade_int(rw)
 208 #endif
 209 #if defined(INVARIANTS) || defined(INVARIANT_SUPPORT)
 210 #define _rw_assert(rw, w, f, l)                                         \
 211         __rw_assert(&(rw)->rw_lock, w, f, l)
 212 #endif
 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)   __extension__ ({                                \
 237         if (rw_wowned(rw))                                              \
 238                 rw_wunlock(rw);                                         \
 239         else                                                            \
 240                 rw_runlock(rw);                                         \
 241         (void)0; /* ensure void type for expression */                  \
 242 })
 243 #define rw_sleep(chan, rw, pri, wmesg, timo)                            \
 244         _sleep((chan), &(rw)->lock_object, (pri), (wmesg),              \
 245             tick_sbt * (timo), 0, C_HARDCLOCK)
 246
 247 #define rw_initialized(rw)      lock_initialized(&(rw)->lock_object)
 248
 249 struct rw_args {
 250         void            *ra_rw;
 251         const char      *ra_desc;
 252         int             ra_flags;
 253 };
 254
 255 #define RW_SYSINIT_FLAGS(name, rw, desc, flags)                         \
 256         static struct rw_args name##_args = {                           \
 257                 (rw),                                                   \
 258                 (desc),                                                 \
 259                 (flags),                                                \
 260         };                                                              \
 261         SYSINIT(name##_rw_sysinit, SI_SUB_LOCK, SI_ORDER_MIDDLE,        \
 262             rw_sysinit, &name##_args);                                  \
 263         SYSUNINIT(name##_rw_sysuninit, SI_SUB_LOCK, SI_ORDER_MIDDLE,    \
 264             _rw_destroy, __DEVOLATILE(void *, &(rw)->rw_lock))
 265
 266 #define RW_SYSINIT(name, rw, desc)      RW_SYSINIT_FLAGS(name, rw, desc, 0)
 267
 268 /*
 269  * Options passed to rw_init_flags().
 270  */
 271 #define RW_DUPOK        0x01
 272 #define RW_NOPROFILE    0x02
 273 #define RW_NOWITNESS    0x04
 274 #define RW_QUIET        0x08
 275 #define RW_RECURSE      0x10
 276 #define RW_NEW          0x20
 277
 278 /*
 279  * The INVARIANTS-enabled rw_assert() functionality.
 280  *
 281  * The constants need to be defined for INVARIANT_SUPPORT infrastructure
 282  * support as _rw_assert() itself uses them and the latter implies that
 283  * _rw_assert() must build.
 284  */
 285 #if defined(INVARIANTS) || defined(INVARIANT_SUPPORT)
 286 #define RA_LOCKED               LA_LOCKED
 287 #define RA_RLOCKED              LA_SLOCKED
 288 #define RA_WLOCKED              LA_XLOCKED
 289 #define RA_UNLOCKED             LA_UNLOCKED
 290 #define RA_RECURSED             LA_RECURSED
 291 #define RA_NOTRECURSED          LA_NOTRECURSED
 292 #endif
 293
 294 #ifdef INVARIANTS
 295 #define rw_assert(rw, what)     _rw_assert((rw), (what), LOCK_FILE, LOCK_LINE)
 296 #else
 297 #define rw_assert(rw, what)
 298 #endif
 299
 300 #endif /* _KERNEL */
 301 #endif /* !_SYS_RWLOCK_H_ */