Date: Sun, 9 Nov 2025 00:36:23 GMT From: Konstantin Belousov <kib@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-branches@FreeBSD.org Subject: git: 21b0a62ebcdc - stable/15 - atomic.9: fix description of acquire and release Message-ID: <202511090036.5A90aNUN096918@gitrepo.freebsd.org>
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The branch stable/15 has been updated by kib: URL: https://cgit.FreeBSD.org/src/commit/?id=21b0a62ebcdcb5453a4d3ff824c8a827e1413e78 commit 21b0a62ebcdcb5453a4d3ff824c8a827e1413e78 Author: Konstantin Belousov <kib@FreeBSD.org> AuthorDate: 2025-10-05 08:39:32 +0000 Commit: Konstantin Belousov <kib@FreeBSD.org> CommitDate: 2025-11-09 00:35:52 +0000 atomic.9: fix description of acquire and release (cherry picked from commit f26382dd72dfc710a8cc7159364a8166e22a4254) --- share/man/man9/atomic.9 | 27 +++++++++++++++++---------- 1 file changed, 17 insertions(+), 10 deletions(-) diff --git a/share/man/man9/atomic.9 b/share/man/man9/atomic.9 index c9133c6311a5..674959648330 100644 --- a/share/man/man9/atomic.9 +++ b/share/man/man9/atomic.9 @@ -182,35 +182,42 @@ This variant is the default. The second variant has acquire semantics, and the third variant has release semantics. .Pp -When an atomic operation has acquire semantics, the operation must have +An atomic operation can only have +.Em acquire +semantics if it performs a load +from memory. +When an atomic operation has acquire semantics, a load performed as +part of the operation must have completed before any subsequent load or store (by program order) is performed. Conversely, acquire semantics do not require that prior loads or stores have -completed before the atomic operation is performed. -An atomic operation can only have acquire semantics if it performs a load -from memory. +completed before a load from the atomic operation is performed. To denote acquire semantics, the suffix .Dq Li _acq is inserted into the function name immediately prior to the .Dq Li _ Ns Aq Fa type suffix. -For example, to subtract two integers ensuring that the subtraction is +For example, to subtract two integers ensuring that the load of +the value from memory is completed before any subsequent loads and stores are performed, use .Fn atomic_subtract_acq_int . .Pp +An atomic operation can only have +.Em release +semantics if it performs a store to memory. When an atomic operation has release semantics, all prior loads or stores -(by program order) must have completed before the operation is performed. -Conversely, release semantics do not require that the atomic operation must +(by program order) must have completed before a store executed as part of +the operation that is performed. +Conversely, release semantics do not require that a store from the atomic +operation must have completed before any subsequent load or store is performed. -An atomic operation can only have release semantics if it performs a store -to memory. To denote release semantics, the suffix .Dq Li _rel is inserted into the function name immediately prior to the .Dq Li _ Ns Aq Fa type suffix. For example, to add two long integers ensuring that all prior loads and -stores are completed before the addition is performed, use +stores are completed before the store of the result is performed, use .Fn atomic_add_rel_long . .Pp When a release operation by one threadhome | help
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