1150629Sjhb/*- 2150629Sjhb * Copyright (c) 2005 John Baldwin <jhb@FreeBSD.org> 3150629Sjhb * All rights reserved. 4150629Sjhb * 5150629Sjhb * Redistribution and use in source and binary forms, with or without 6150629Sjhb * modification, are permitted provided that the following conditions 7150629Sjhb * are met: 8150629Sjhb * 1. Redistributions of source code must retain the above copyright 9150629Sjhb * notice, this list of conditions and the following disclaimer. 10150629Sjhb * 2. Redistributions in binary form must reproduce the above copyright 11150629Sjhb * notice, this list of conditions and the following disclaimer in the 12150629Sjhb * documentation and/or other materials provided with the distribution. 13150629Sjhb * 14150629Sjhb * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 15150629Sjhb * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 16150629Sjhb * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 17150629Sjhb * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 18150629Sjhb * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 19150629Sjhb * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 20150629Sjhb * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 21150629Sjhb * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 22150629Sjhb * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 23150629Sjhb * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 24150629Sjhb * SUCH DAMAGE. 25150629Sjhb * 26150629Sjhb * $FreeBSD$ 27150629Sjhb */ 28150629Sjhb 29150629Sjhb#ifndef __SYS_REFCOUNT_H__ 30150629Sjhb#define __SYS_REFCOUNT_H__ 31150629Sjhb 32238828Sglebius#include <sys/limits.h> 33180762Sdes#include <machine/atomic.h> 34180762Sdes 35180762Sdes#ifdef _KERNEL 36180762Sdes#include <sys/systm.h> 37180762Sdes#else 38180762Sdes#define KASSERT(exp, msg) /* */ 39180762Sdes#endif 40180762Sdes 41150629Sjhbstatic __inline void 42150629Sjhbrefcount_init(volatile u_int *count, u_int value) 43150629Sjhb{ 44150629Sjhb 45150629Sjhb *count = value; 46150629Sjhb} 47150629Sjhb 48150629Sjhbstatic __inline void 49150629Sjhbrefcount_acquire(volatile u_int *count) 50150629Sjhb{ 51150629Sjhb 52238828Sglebius KASSERT(*count < UINT_MAX, ("refcount %p overflowed", count)); 53150629Sjhb atomic_add_acq_int(count, 1); 54150629Sjhb} 55150629Sjhb 56150629Sjhbstatic __inline int 57150629Sjhbrefcount_release(volatile u_int *count) 58150629Sjhb{ 59180762Sdes u_int old; 60150629Sjhb 61180762Sdes /* XXX: Should this have a rel membar? */ 62180762Sdes old = atomic_fetchadd_int(count, -1); 63180762Sdes KASSERT(old > 0, ("negative refcount %p", count)); 64180762Sdes return (old == 1); 65150629Sjhb} 66150629Sjhb 67150629Sjhb#endif /* ! __SYS_REFCOUNT_H__ */ 68