/*- * SPDX-License-Identifier: BSD-2-Clause-FreeBSD * * Copyright (c) 2006 John Baldwin * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. * * $FreeBSD$ */ #ifndef _SYS_RWLOCK_H_ #define _SYS_RWLOCK_H_ #include #include #include #include #ifdef _KERNEL #include #include #endif /* * The rw_lock field consists of several fields. The low bit indicates * if the lock is locked with a read (shared) or write (exclusive) lock. * A value of 0 indicates a write lock, and a value of 1 indicates a read * lock. Bit 1 is a boolean indicating if there are any threads waiting * for a read lock. Bit 2 is a boolean indicating if there are any threads * waiting for a write lock. The rest of the variable's definition is * dependent on the value of the first bit. For a write lock, it is a * pointer to the thread holding the lock, similar to the mtx_lock field of * mutexes. For read locks, it is a count of read locks that are held. * * When the lock is not locked by any thread, it is encoded as a read lock * with zero waiters. */ #define RW_LOCK_READ 0x01 #define RW_LOCK_READ_WAITERS 0x02 #define RW_LOCK_WRITE_WAITERS 0x04 #define RW_LOCK_WRITE_SPINNER 0x08 #define RW_LOCK_WRITER_RECURSED 0x10 #define RW_LOCK_FLAGMASK \ (RW_LOCK_READ | RW_LOCK_READ_WAITERS | RW_LOCK_WRITE_WAITERS | \ RW_LOCK_WRITE_SPINNER | RW_LOCK_WRITER_RECURSED) #define RW_LOCK_WAITERS (RW_LOCK_READ_WAITERS | RW_LOCK_WRITE_WAITERS) #define RW_OWNER(x) ((x) & ~RW_LOCK_FLAGMASK) #define RW_READERS_SHIFT 5 #define RW_READERS(x) (RW_OWNER((x)) >> RW_READERS_SHIFT) #define RW_READERS_LOCK(x) ((x) << RW_READERS_SHIFT | RW_LOCK_READ) #define RW_ONE_READER (1 << RW_READERS_SHIFT) #define RW_UNLOCKED RW_READERS_LOCK(0) #define RW_DESTROYED (RW_LOCK_READ_WAITERS | RW_LOCK_WRITE_WAITERS) #ifdef _KERNEL #define rw_recurse lock_object.lo_data #define RW_READ_VALUE(x) ((x)->rw_lock) /* Very simple operations on rw_lock. */ /* Try to obtain a write lock once. */ #define _rw_write_lock(rw, tid) \ atomic_cmpset_acq_ptr(&(rw)->rw_lock, RW_UNLOCKED, (tid)) #define _rw_write_lock_fetch(rw, vp, tid) \ atomic_fcmpset_acq_ptr(&(rw)->rw_lock, vp, (tid)) /* Release a write lock quickly if there are no waiters. */ #define _rw_write_unlock(rw, tid) \ atomic_cmpset_rel_ptr(&(rw)->rw_lock, (tid), RW_UNLOCKED) #define _rw_write_unlock_fetch(rw, tid) \ atomic_fcmpset_rel_ptr(&(rw)->rw_lock, (tid), RW_UNLOCKED) /* * Full lock operations that are suitable to be inlined in non-debug * kernels. If the lock cannot be acquired or released trivially then * the work is deferred to another function. */ /* Acquire a write lock. */ #define __rw_wlock(rw, tid, file, line) do { \ uintptr_t _tid = (uintptr_t)(tid); \ uintptr_t _v = RW_UNLOCKED; \ \ if (__predict_false(LOCKSTAT_PROFILE_ENABLED(rw__acquire) || \ !_rw_write_lock_fetch((rw), &_v, _tid))) \ _rw_wlock_hard((rw), _v, (file), (line)); \ } while (0) /* Release a write lock. */ #define __rw_wunlock(rw, tid, file, line) do { \ uintptr_t _v = (uintptr_t)(tid); \ \ if (__predict_false(LOCKSTAT_PROFILE_ENABLED(rw__release) || \ !_rw_write_unlock_fetch((rw), &_v))) \ _rw_wunlock_hard((rw), _v, (file), (line)); \ } while (0) /* * Function prototypes. Routines that start with _ are not part of the * external API and should not be called directly. Wrapper macros should * be used instead. */ void _rw_init_flags(volatile uintptr_t *c, const char *name, int opts); void _rw_destroy(volatile uintptr_t *c); void rw_sysinit(void *arg); int _rw_wowned(const volatile uintptr_t *c); void _rw_wlock_cookie(volatile uintptr_t *c, const char *file, int line); int __rw_try_wlock_int(struct rwlock *rw LOCK_FILE_LINE_ARG_DEF); int __rw_try_wlock(volatile uintptr_t *c, const char *file, int line); void _rw_wunlock_cookie(volatile uintptr_t *c, const char *file, int line); void __rw_rlock_int(struct rwlock *rw LOCK_FILE_LINE_ARG_DEF); void __rw_rlock(volatile uintptr_t *c, const char *file, int line); int __rw_try_rlock_int(struct rwlock *rw LOCK_FILE_LINE_ARG_DEF); int __rw_try_rlock(volatile uintptr_t *c, const char *file, int line); void _rw_runlock_cookie_int(struct rwlock *rw LOCK_FILE_LINE_ARG_DEF); void _rw_runlock_cookie(volatile uintptr_t *c, const char *file, int line); void __rw_wlock_hard(volatile uintptr_t *c, uintptr_t v LOCK_FILE_LINE_ARG_DEF); void __rw_wunlock_hard(volatile uintptr_t *c, uintptr_t v LOCK_FILE_LINE_ARG_DEF); int __rw_try_upgrade_int(struct rwlock *rw LOCK_FILE_LINE_ARG_DEF); int __rw_try_upgrade(volatile uintptr_t *c, const char *file, int line); void __rw_downgrade_int(struct rwlock *rw LOCK_FILE_LINE_ARG_DEF); void __rw_downgrade(volatile uintptr_t *c, const char *file, int line); #if defined(INVARIANTS) || defined(INVARIANT_SUPPORT) void __rw_assert(const volatile uintptr_t *c, int what, const char *file, int line); #endif /* * Top-level macros to provide lock cookie once the actual rwlock is passed. * They will also prevent passing a malformed object to the rwlock KPI by * failing compilation as the rw_lock reserved member will not be found. */ #define rw_init(rw, n) \ _rw_init_flags(&(rw)->rw_lock, n, 0) #define rw_init_flags(rw, n, o) \ _rw_init_flags(&(rw)->rw_lock, n, o) #define rw_destroy(rw) \ _rw_destroy(&(rw)->rw_lock) #define rw_wowned(rw) \ _rw_wowned(&(rw)->rw_lock) #define _rw_wlock(rw, f, l) \ _rw_wlock_cookie(&(rw)->rw_lock, f, l) #define _rw_try_wlock(rw, f, l) \ __rw_try_wlock(&(rw)->rw_lock, f, l) #define _rw_wunlock(rw, f, l) \ _rw_wunlock_cookie(&(rw)->rw_lock, f, l) #define _rw_try_rlock(rw, f, l) \ __rw_try_rlock(&(rw)->rw_lock, f, l) #if LOCK_DEBUG > 0 #define _rw_rlock(rw, f, l) \ __rw_rlock(&(rw)->rw_lock, f, l) #define _rw_runlock(rw, f, l) \ _rw_runlock_cookie(&(rw)->rw_lock, f, l) #else #define _rw_rlock(rw, f, l) \ __rw_rlock_int((struct rwlock *)rw) #define _rw_runlock(rw, f, l) \ _rw_runlock_cookie_int((struct rwlock *)rw) #endif #if LOCK_DEBUG > 0 #define _rw_wlock_hard(rw, v, f, l) \ __rw_wlock_hard(&(rw)->rw_lock, v, f, l) #define _rw_wunlock_hard(rw, v, f, l) \ __rw_wunlock_hard(&(rw)->rw_lock, v, f, l) #define _rw_try_upgrade(rw, f, l) \ __rw_try_upgrade(&(rw)->rw_lock, f, l) #define _rw_downgrade(rw, f, l) \ __rw_downgrade(&(rw)->rw_lock, f, l) #else #define _rw_wlock_hard(rw, v, f, l) \ __rw_wlock_hard(&(rw)->rw_lock, v) #define _rw_wunlock_hard(rw, v, f, l) \ __rw_wunlock_hard(&(rw)->rw_lock, v) #define _rw_try_upgrade(rw, f, l) \ __rw_try_upgrade_int(rw) #define _rw_downgrade(rw, f, l) \ __rw_downgrade_int(rw) #endif #if defined(INVARIANTS) || defined(INVARIANT_SUPPORT) #define _rw_assert(rw, w, f, l) \ __rw_assert(&(rw)->rw_lock, w, f, l) #endif /* * Public interface for lock operations. */ #ifndef LOCK_DEBUG #error LOCK_DEBUG not defined, include before #endif #if LOCK_DEBUG > 0 || defined(RWLOCK_NOINLINE) #define rw_wlock(rw) _rw_wlock((rw), LOCK_FILE, LOCK_LINE) #define rw_wunlock(rw) _rw_wunlock((rw), LOCK_FILE, LOCK_LINE) #else #define rw_wlock(rw) \ __rw_wlock((rw), curthread, LOCK_FILE, LOCK_LINE) #define rw_wunlock(rw) \ __rw_wunlock((rw), curthread, LOCK_FILE, LOCK_LINE) #endif #define rw_rlock(rw) _rw_rlock((rw), LOCK_FILE, LOCK_LINE) #define rw_runlock(rw) _rw_runlock((rw), LOCK_FILE, LOCK_LINE) #define rw_try_rlock(rw) _rw_try_rlock((rw), LOCK_FILE, LOCK_LINE) #define rw_try_upgrade(rw) _rw_try_upgrade((rw), LOCK_FILE, LOCK_LINE) #define rw_try_wlock(rw) _rw_try_wlock((rw), LOCK_FILE, LOCK_LINE) #define rw_downgrade(rw) _rw_downgrade((rw), LOCK_FILE, LOCK_LINE) #define rw_unlock(rw) do { \ if (rw_wowned(rw)) \ rw_wunlock(rw); \ else \ rw_runlock(rw); \ } while (0) #define rw_sleep(chan, rw, pri, wmesg, timo) \ _sleep((chan), &(rw)->lock_object, (pri), (wmesg), \ tick_sbt * (timo), 0, C_HARDCLOCK) #define rw_initialized(rw) lock_initialized(&(rw)->lock_object) struct rw_args { void *ra_rw; const char *ra_desc; int ra_flags; }; #define RW_SYSINIT_FLAGS(name, rw, desc, flags) \ static struct rw_args name##_args = { \ (rw), \ (desc), \ (flags), \ }; \ SYSINIT(name##_rw_sysinit, SI_SUB_LOCK, SI_ORDER_MIDDLE, \ rw_sysinit, &name##_args); \ SYSUNINIT(name##_rw_sysuninit, SI_SUB_LOCK, SI_ORDER_MIDDLE, \ _rw_destroy, __DEVOLATILE(void *, &(rw)->rw_lock)) #define RW_SYSINIT(name, rw, desc) RW_SYSINIT_FLAGS(name, rw, desc, 0) /* * Options passed to rw_init_flags(). */ #define RW_DUPOK 0x01 #define RW_NOPROFILE 0x02 #define RW_NOWITNESS 0x04 #define RW_QUIET 0x08 #define RW_RECURSE 0x10 #define RW_NEW 0x20 /* * The INVARIANTS-enabled rw_assert() functionality. * * The constants need to be defined for INVARIANT_SUPPORT infrastructure * support as _rw_assert() itself uses them and the latter implies that * _rw_assert() must build. */ #if defined(INVARIANTS) || defined(INVARIANT_SUPPORT) #define RA_LOCKED LA_LOCKED #define RA_RLOCKED LA_SLOCKED #define RA_WLOCKED LA_XLOCKED #define RA_UNLOCKED LA_UNLOCKED #define RA_RECURSED LA_RECURSED #define RA_NOTRECURSED LA_NOTRECURSED #endif #ifdef INVARIANTS #define rw_assert(rw, what) _rw_assert((rw), (what), LOCK_FILE, LOCK_LINE) #else #define rw_assert(rw, what) #endif #endif /* _KERNEL */ #endif /* !_SYS_RWLOCK_H_ */