87 lines
2.4 KiB
C
87 lines
2.4 KiB
C
/*
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* Copyright (c) 2002, Jeffrey Roberson <jeff@freebsd.org>
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice unmodified, this list of conditions, and the following
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* disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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* $FreeBSD$
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*
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*/
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#ifndef _SYS_UMTX_H_
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#define _SYS_UMTX_H_
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/*
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* See pthread_*
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*/
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#define UMTX_UNOWNED 0x0
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#define UMTX_CONTESTED 0x1
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struct umtx {
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thr_id_t u_owner; /* Owner of the mutex. */
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};
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#ifndef _KERNEL
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/*
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* System calls for acquiring and releasing contested mutexes.
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*/
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int _umtx_lock(struct umtx *mtx);
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int _umtx_unlock(struct umtx *mtx);
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/*
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* Standard api. Try uncontested acquire/release and asks the
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* kernel to resolve failures.
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*/
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static __inline int
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umtx_lock(struct umtx *umtx, thr_id_t id)
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{
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if (atomic_cmpset_acq_ptr(&umtx->u_owner, UMTX_UNOWNED, id) == 0)
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if (_umtx_lock(umtx) == -1)
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return (errno);
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return (0);
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}
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static __inline int
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umtx_trylock(struct umtx *umtx, thr_id_t id)
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{
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if (atomic_cmpset_acq_ptr(&umtx->u_owner, UMTX_UNOWNED, id) == 0)
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return (EBUSY);
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return (0);
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}
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static __inline int
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umtx_unlock(struct umtx *umtx, thr_id_t id)
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{
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if (atomic_cmpset_rel_ptr(&umtx->u_owner, id, UMTX_UNOWNED) == 0)
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if (_umtx_unlock(umtx) == -1)
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return (errno);
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return (0);
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}
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#endif /* !_KERNEL */
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#endif /* !_SYS_UMTX_H_ */
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