diff --git a/sys/sys/refcount.h b/sys/sys/refcount.h index 44edbdf953a0..19a8f38772a0 100644 --- a/sys/sys/refcount.h +++ b/sys/sys/refcount.h @@ -1,129 +1,136 @@ /*- * SPDX-License-Identifier: BSD-2-Clause-FreeBSD * * Copyright (c) 2005 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_REFCOUNT_H__ #define __SYS_REFCOUNT_H__ #include #include #ifdef _KERNEL #include #else #include #define KASSERT(exp, msg) /* */ #endif static __inline void refcount_init(volatile u_int *count, u_int value) { *count = value; } static __inline void refcount_acquire(volatile u_int *count) { KASSERT(*count < UINT_MAX, ("refcount %p overflowed", count)); atomic_add_int(count, 1); } static __inline __result_use_check bool refcount_acquire_checked(volatile u_int *count) { u_int lcount; for (lcount = *count;;) { if (__predict_false(lcount + 1 < lcount)) return (false); if (__predict_true(atomic_fcmpset_int(count, &lcount, lcount + 1) == 1)) return (true); } } static __inline bool -refcount_release(volatile u_int *count) +refcount_releasen(volatile u_int *count, u_int n) { u_int old; atomic_thread_fence_rel(); - old = atomic_fetchadd_int(count, -1); + old = atomic_fetchadd_int(count, -n); KASSERT(old > 0, ("refcount %p is zero", count)); - if (old > 1) + if (old > n) return (false); /* * Last reference. Signal the user to call the destructor. * - * Ensure that the destructor sees all updates. The fence_rel - * at the start of the function synchronized with this fence. + * Ensure that the destructor sees all updates. This synchronizes with + * release fences from all routines which drop the count. */ atomic_thread_fence_acq(); return (true); } +static __inline bool +refcount_release(volatile u_int *count) +{ + + return (refcount_releasen(count, 1)); +} + /* * This functions returns non-zero if the refcount was * incremented. Else zero is returned. * * A temporary hack until refcount_* APIs are sorted out. */ static __inline __result_use_check bool refcount_acquire_if_not_zero(volatile u_int *count) { u_int old; old = *count; for (;;) { KASSERT(old < UINT_MAX, ("refcount %p overflowed", count)); if (old == 0) return (false); if (atomic_fcmpset_int(count, &old, old + 1)) return (true); } } static __inline __result_use_check bool refcount_release_if_not_last(volatile u_int *count) { u_int old; old = *count; for (;;) { KASSERT(old > 0, ("refcount %p is zero", count)); if (old == 1) return (false); if (atomic_fcmpset_int(count, &old, old - 1)) return (true); } } #endif /* ! __SYS_REFCOUNT_H__ */