1 /*- 2 * Copyright (c) 2005 John Baldwin <jhb@FreeBSD.org> 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 24 * SUCH DAMAGE. 25 * 26 * $FreeBSD$ 27 */ 28 29 #ifndef __REFCNT_H__ 30 #define __REFCNT_H__ 31 32 #include <machine/atomic.h> 33 34 #include "pjdlog.h" 35 36 typedef unsigned int refcnt_t; 37 38 static __inline void 39 refcnt_init(refcnt_t *count, unsigned int v) 40 { 41 42 *count = v; 43 } 44 45 static __inline void 46 refcnt_acquire(refcnt_t *count) 47 { 48 49 atomic_add_acq_int(count, 1); 50 } 51 52 static __inline unsigned int 53 refcnt_release(refcnt_t *count) 54 { 55 unsigned int old; 56 57 /* XXX: Should this have a rel membar? */ 58 old = atomic_fetchadd_int(count, -1); 59 PJDLOG_ASSERT(old > 0); 60 return (old - 1); 61 } 62 63 #endif /* ! __REFCNT_H__ */ 64