Date: Mon, 16 Apr 2001 19:50:06 -0700 (PDT) From: John Baldwin <jhb@FreeBSD.org> To: cvs-committers@FreeBSD.org, cvs-all@FreeBSD.org Subject: cvs commit: src/sys/alpha/include atomic.h Message-ID: <200104170250.f3H2o6474875@freefall.freebsd.org>
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jhb 2001/04/16 19:50:06 PDT
Modified files:
sys/alpha/include atomic.h
Log:
- Fix memory barriers in atomic operations so that the barriers are always
"inside" of locked regions. That is, an acquire atomic operation will
always enforce a memory barrier after the atomic operation and a release
operation will always enforce a memory barrier before the atomic
operation.
- Explicitly use 'mb' instead of 'wmb' in release atomic operations. The
'wmb' memory barrier is not strong enough to guarantee coherence with
other processors. This is effectively a nop since alpha_wmb() actually
performs a 'mb' and not a 'wmb', but I wanted the code to be more
correct since at some point in the future alpha_wmb()'s implementation
may switch to being a real 'wmb'.
Revision Changes Path
1.10 +27 -21 src/sys/alpha/include/atomic.h
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