rwlock.h

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    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  * $FreeBSD$
   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  */
  127 void    _rw_init_flags(volatile uintptr_t *c, const char *name, int opts);
  128 void    _rw_destroy(volatile uintptr_t *c);
  129 void    rw_sysinit(void *arg);
  130 int     _rw_wowned(const volatile uintptr_t *c);
  131 void    _rw_wlock_cookie(volatile uintptr_t *c, const char *file, int line);
  132 int     __rw_try_wlock_int(struct rwlock *rw LOCK_FILE_LINE_ARG_DEF);
  133 int     __rw_try_wlock(volatile uintptr_t *c, const char *file, int line);
  134 void    _rw_wunlock_cookie(volatile uintptr_t *c, const char *file, int line);
  135 void    __rw_rlock_int(struct rwlock *rw LOCK_FILE_LINE_ARG_DEF);
  136 void    __rw_rlock(volatile uintptr_t *c, const char *file, int line);
  137 int     __rw_try_rlock_int(struct rwlock *rw LOCK_FILE_LINE_ARG_DEF);
  138 int     __rw_try_rlock(volatile uintptr_t *c, const char *file, int line);
  139 void    _rw_runlock_cookie_int(struct rwlock *rw LOCK_FILE_LINE_ARG_DEF);
  140 void    _rw_runlock_cookie(volatile uintptr_t *c, const char *file, int line);
  141 void    __rw_wlock_hard(volatile uintptr_t *c, uintptr_t v
  142             LOCK_FILE_LINE_ARG_DEF);
  143 void    __rw_wunlock_hard(volatile uintptr_t *c, uintptr_t v
  144             LOCK_FILE_LINE_ARG_DEF);
  145 int     __rw_try_upgrade_int(struct rwlock *rw LOCK_FILE_LINE_ARG_DEF);
  146 int     __rw_try_upgrade(volatile uintptr_t *c, const char *file, int line);
  147 void    __rw_downgrade_int(struct rwlock *rw LOCK_FILE_LINE_ARG_DEF);
  148 void    __rw_downgrade(volatile uintptr_t *c, const char *file, int line);
  149 #if defined(INVARIANTS) || defined(INVARIANT_SUPPORT)
  150 void    __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 
  245 struct 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_ */
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FreeBSD/Linux Kernel Cross Reference sys/sys/rwlock.h

FreeBSD/Linux Kernel Cross Reference
sys/sys/rwlock.h
