refcnt.h revision 249969
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 * 3. Neither the name of the author nor the names of any co-contributors 14 * may be used to endorse or promote products derived from this software 15 * without specific prior written permission. 16 * 17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 20 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 27 * SUCH DAMAGE. 28 * 29 * $FreeBSD: head/sbin/hastd/refcnt.h 249969 2013-04-27 05:01:29Z ed $ 30 */ 31 32#ifndef __REFCNT_H__ 33#define __REFCNT_H__ 34 35#include <stdatomic.h> 36 37#include "pjdlog.h" 38 39typedef atomic_uint refcnt_t; 40 41static __inline void 42refcnt_init(refcnt_t *count, unsigned int v) 43{ 44 45 atomic_init(count, v); 46} 47 48static __inline void 49refcnt_acquire(refcnt_t *count) 50{ 51 52 atomic_fetch_add_explicit(count, 1, memory_order_acquire); 53} 54 55static __inline unsigned int 56refcnt_release(refcnt_t *count) 57{ 58 unsigned int old; 59 60 /* XXX: Should this have a rel membar? */ 61 old = atomic_fetch_sub(count, 1); 62 PJDLOG_ASSERT(old > 0); 63 return (old - 1); 64} 65 66#endif /* ! __REFCNT_H__ */ 67