Date: Sat, 27 Jun 2015 09:47:28 +0000 (UTC) From: Konstantin Belousov <kib@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-stable@freebsd.org, svn-src-stable-10@freebsd.org Subject: svn commit: r284888 - stable/10/share/man/man9 Message-ID: <201506270947.t5R9lS16053867@svn.freebsd.org>
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Author: kib Date: Sat Jun 27 09:47:28 2015 New Revision: 284888 URL: https://svnweb.freebsd.org/changeset/base/284888 Log: MFC r284646: The barriers, provided by _acq and _rel atomics, are acquire and release barriers, not read and write barriers. Modified: stable/10/share/man/man9/atomic.9 Directory Properties: stable/10/ (props changed) Modified: stable/10/share/man/man9/atomic.9 ============================================================================== --- stable/10/share/man/man9/atomic.9 Sat Jun 27 09:44:14 2015 (r284887) +++ stable/10/share/man/man9/atomic.9 Sat Jun 27 09:47:28 2015 (r284888) @@ -23,7 +23,7 @@ .\" .\" $FreeBSD$ .\" -.Dd August 20, 2013 +.Dd June 20, 2015 .Dt ATOMIC 9 .Os .Sh NAME @@ -123,7 +123,9 @@ The first form just performs the operati The second form uses a read memory barrier, and the third variant uses a write memory barrier. .Pp -The second variant of each operation includes a read memory barrier. +The second variant of each operation includes an +.Em acquire +memory barrier. This barrier ensures that the effects of this operation are completed before the effects of any later data accesses. As a result, the operation is said to have acquire semantics as it acquires a @@ -137,7 +139,9 @@ For example, to subtract two integers en happen after the subtraction is performed, use .Fn atomic_subtract_acq_int . .Pp -The third variant of each operation includes a write memory barrier. +The third variant of each operation includes a +.Em release +memory barrier. This ensures that all effects of all previous data accesses are completed before this operation takes place. As a result, the operation is said to have release semantics as it releases
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