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/*
* Copyright (c) 2002, Jeffrey Roberson <jeff@freebsd.org>
* All rights reserved.
*
* 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 unmodified, 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 ``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 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_UMTX_H_
#define _SYS_UMTX_H_
/*
* See pthread_*
*/
#define UMTX_UNOWNED NULL
#define UMTX_CONTESTED 0x1
struct umtx {
thr_id_t u_owner; /* Owner of the mutex. */
thr_id_t u_blocked; /* First blocked thread, owns wait queue. */
};
#ifndef _KERNEL
/*
* System calls for acquiring and releasing contested mutexes.
*/
int _umtx_lock(struct umtx *mtx);
int _umtx_unlock(struct umtx *mtx);
/*
* Standard api. Try uncontested acquire/release and asks the
* kernel to resolve failures.
*/
static __inline int
umtx_lock(struct umtx *umtx, thr_id_t id)
{
if (atomic_cmpset_acq_ptr(&umtx->u_owner, UMTX_UNOWNED, id) == 0)
if (_umtx_lock(umtx) == -1)
return (errno);
return (0);
}
static __inline int
umtx_trylock(struct umtx *umtx, thr_id_t id)
{
if (atomic_cmpset_acq_ptr(&umtx->u_owner, UMTX_UNOWNED, id) == 0)
return (EBUSY);
return (0);
}
static __inline int
umtx_unlock(struct umtx *umtx, thr_id_t id)
{
if (atomic_cmpset_rel_ptr(&umtx->u_owner, id, UMTX_UNOWNED) == 0)
if (_umtx_unlock(umtx) == -1)
return (errno);
return (0);
}
#endif /* !_KERNEL */
#endif /* !_SYS_UMTX_H_ */
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