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Diffstat (limited to 'static/openbsd/man9/membar_sync.9')
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diff --git a/static/openbsd/man9/membar_sync.9 b/static/openbsd/man9/membar_sync.9 new file mode 100644 index 00000000..c2e8de71 --- /dev/null +++ b/static/openbsd/man9/membar_sync.9 @@ -0,0 +1,124 @@ +.\" $OpenBSD: membar_sync.9,v 1.4 2022/03/13 22:16:59 bluhm Exp $ +.\" +.\" Copyright (c) 2007, 2008 The NetBSD Foundation, Inc. +.\" All rights reserved. +.\" +.\" This code is derived from software contributed to The NetBSD Foundation +.\" by Jason R. Thorpe. +.\" +.\" 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, 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 NETBSD FOUNDATION, INC. AND CONTRIBUTORS +.\" ``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 FOUNDATION OR CONTRIBUTORS +.\" 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. +.\" +.Dd $Mdocdate: March 13 2022 $ +.Dt MEMBAR 9 +.Os +.Sh NAME +.Nm membar_enter , +.Nm membar_exit , +.Nm membar_producer , +.Nm membar_consumer , +.Nm membar_sync , +.Nm membar_enter_after_atomic , +.Nm membar_exit_before_atomic +.Nd memory access barrier operations +.Sh SYNOPSIS +.In sys/atomic.h +.Ft void +.Fn membar_enter "void" +.Ft void +.Fn membar_exit "void" +.Ft void +.Fn membar_producer "void" +.Ft void +.Fn membar_consumer "void" +.Ft void +.Fn membar_sync "void" +.Ft void +.Fn membar_enter_after_atomic "void" +.Ft void +.Fn membar_exit_before_atomic "void" +.Sh DESCRIPTION +The membar set of functions provide an interface for issuing memory barrier +access operations with respect to multiple processors in the system. +.Bl -tag -width "mem" +.It Fn membar_enter +Any store preceding +.Fn membar_enter +will reach global visibility before all loads and stores following it. +.Pp +.Fn membar_enter +is typically used in code that implements locking primitives to ensure +that a lock protects its data. +.It Fn membar_exit +All loads and stores preceding +.Fn membar_exit +will reach global visibility before any store that follows it. +.Pp +.Fn membar_exit +is typically used in code that implements locking primitives to ensure +that a lock protects its data. +.It Fn membar_producer +All stores preceding the memory barrier will reach global visibility +before any stores after the memory barrier reach global visibility. +.It Fn membar_consumer +All loads preceding the memory barrier will complete before any loads +after the memory barrier complete. +.It Fn membar_sync +All loads and stores preceding the memory barrier will complete and +reach global visibility before any loads and stores after the memory +barrier complete and reach global visibility. +.It Fn membar_enter_after_atomic +An atomic operation preceding +.Fn membar_enter_after_atomic +will reach global visibility before all loads and stores following it. +The atomic operation is used to protect the start of a critical section. +.It Fn membar_exit_before_atomic +All loads and stores preceding +.Fn membar_exit_before_atomic +will reach global visibility before atomic operation that follows it. +The atomic operation is used to protect the end of a critical section. +.El +.Pp +The atomic operations that can be used with +.Fn membar_enter_after_atomic +and +.Fn membar_exit_before_atomic +are the atomic_add, atomic_sub, atomic_inc, atomic_dec, and atomic_cas +set of functions. +For other cases use +.Fn membar_enter +or +.Fn membar_exit . +.Sh CONTEXT +.Fn membar_enter , +.Fn membar_exit , +.Fn membar_producer , +.Fn membar_consumer , +.Fn membar_sync , +.Fn membar_enter_after_atomic , +.Fn membar_exit_before_atomic +can all be called during autoconf, from process context, or from +interrupt context. +.Sh HISTORY +The membar functions first appeared in +.Nx 5.0 +and +.Ox 5.5 . |