On Sun, Mar 13, 2022 at 10:55:51PM +0100, Mark Kettenis wrote: > You missed atomic_cas.
Fixed. Index: share/man/man9/membar_sync.9 =================================================================== RCS file: /data/mirror/openbsd/cvs/src/share/man/man9/membar_sync.9,v retrieving revision 1.3 diff -u -p -r1.3 membar_sync.9 --- share/man/man9/membar_sync.9 14 Feb 2014 05:11:55 -0000 1.3 +++ share/man/man9/membar_sync.9 13 Mar 2022 21:57:35 -0000 @@ -35,7 +35,9 @@ .Nm membar_exit , .Nm membar_producer , .Nm membar_consumer , -.Nm membar_sync +.Nm membar_sync , +.Nm membar_enter_after_atomic , +.Nm membar_exit_before_atomic .Nd memory access barrier operations .Sh SYNOPSIS .In sys/atomic.h @@ -49,6 +51,10 @@ .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. @@ -79,14 +85,38 @@ after the memory barrier complete. 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 -can all be called during autoconf, from process context, or from interrupt context. +.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
