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553cb3ed46
sys/param.h was manually adjusted to not define __NetBSD_Version__ since it will be defined by the compiler.
156 lines
No EOL
4.4 KiB
C
Vendored
156 lines
No EOL
4.4 KiB
C
Vendored
/* $NetBSD: lock.h,v 1.34 2022/02/13 13:41:17 riastradh Exp $ */
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/*-
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* Copyright (c) 1998, 1999, 2006 The NetBSD Foundation, Inc.
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* All rights reserved.
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*
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* This code is derived from software contributed to The NetBSD Foundation
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* by Paul Kranenburg and Andrew Doran.
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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, this list of conditions and the following 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 NETBSD FOUNDATION, INC. AND CONTRIBUTORS
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* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
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* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*/
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#ifndef _MACHINE_LOCK_H
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#define _MACHINE_LOCK_H
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/*
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* Machine dependent spin lock operations.
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*/
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#if __SIMPLELOCK_UNLOCKED != 0
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#error __SIMPLELOCK_UNLOCKED must be 0 for this implementation
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#endif
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/* XXX So we can expose this to userland. */
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#ifdef __lint__
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#define __ldstub(__addr) (__addr)
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#else /* !__lint__ */
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static __inline int __ldstub(__cpu_simple_lock_t *addr);
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static __inline int __ldstub(__cpu_simple_lock_t *addr)
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{
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int v;
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__asm volatile("ldstub [%1],%0"
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: "=&r" (v)
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: "r" (addr)
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: "memory");
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return v;
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}
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#endif /* __lint__ */
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static __inline void __cpu_simple_lock_init(__cpu_simple_lock_t *)
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__attribute__((__unused__));
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static __inline int __cpu_simple_lock_try(__cpu_simple_lock_t *)
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__attribute__((__unused__));
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static __inline void __cpu_simple_unlock(__cpu_simple_lock_t *)
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__attribute__((__unused__));
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#ifndef __CPU_SIMPLE_LOCK_NOINLINE
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static __inline void __cpu_simple_lock(__cpu_simple_lock_t *)
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__attribute__((__unused__));
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#else
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extern void __cpu_simple_lock(__cpu_simple_lock_t *);
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#endif
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static __inline int
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__SIMPLELOCK_LOCKED_P(const __cpu_simple_lock_t *__ptr)
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{
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return *__ptr == __SIMPLELOCK_LOCKED;
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}
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static __inline int
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__SIMPLELOCK_UNLOCKED_P(const __cpu_simple_lock_t *__ptr)
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{
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return *__ptr == __SIMPLELOCK_UNLOCKED;
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}
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static __inline void
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__cpu_simple_lock_clear(__cpu_simple_lock_t *__ptr)
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{
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*__ptr = __SIMPLELOCK_UNLOCKED;
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}
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static __inline void
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__cpu_simple_lock_set(__cpu_simple_lock_t *__ptr)
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{
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*__ptr = __SIMPLELOCK_LOCKED;
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}
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static __inline void
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__cpu_simple_lock_init(__cpu_simple_lock_t *alp)
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{
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*alp = __SIMPLELOCK_UNLOCKED;
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}
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#ifndef __CPU_SIMPLE_LOCK_NOINLINE
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static __inline void
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__cpu_simple_lock(__cpu_simple_lock_t *alp)
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{
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/*
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* If someone else holds the lock use simple reads until it
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* is released, then retry the atomic operation. This reduces
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* memory bus contention because the cache-coherency logic
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* does not have to broadcast invalidates on the lock while
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* we spin on it.
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*/
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while (__ldstub(alp) != __SIMPLELOCK_UNLOCKED) {
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while (*alp != __SIMPLELOCK_UNLOCKED)
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/* spin */ ;
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}
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/*
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* No memory barrier needed here to make this a load-acquire
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* operation because LDSTUB already implies that. See SPARCv8
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* Reference Manual, Appendix J.4 `Spin Locks', p. 271.
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*/
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}
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#endif /* __CPU_SIMPLE_LOCK_NOINLINE */
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static __inline int
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__cpu_simple_lock_try(__cpu_simple_lock_t *alp)
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{
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/*
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* No memory barrier needed for LDSTUB to be a load-acquire --
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* see __cpu_simple_lock.
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*/
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return (__ldstub(alp) == __SIMPLELOCK_UNLOCKED);
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}
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static __inline void
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__cpu_simple_unlock(__cpu_simple_lock_t *alp)
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{
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/*
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* Insert compiler barrier to prevent instruction re-ordering
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* around the lock release.
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*
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* No memory barrier needed because we run the kernel in TSO.
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* If we ran the kernel in PSO, this would require STBAR.
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*/
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__insn_barrier();
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*alp = __SIMPLELOCK_UNLOCKED;
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}
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#endif /* _MACHINE_LOCK_H */ |