Date: Sat, 16 Nov 2002 09:05:06 -0800 (PST) From: Marcel Moolenaar <marcel@FreeBSD.org> To: cvs-committers@FreeBSD.org, cvs-all@FreeBSD.org Subject: cvs commit: src/lib/libc_r/arch/ia64 _atomic_lock.S Message-ID: <200211161705.gAGH56v5058239@repoman.freebsd.org>
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marcel 2002/11/16 09:05:06 PST
Modified files:
lib/libc_r/arch/ia64 _atomic_lock.S
Log:
Implement the lock with a cmpxchg instruction instead of a xchg.
Both are atomic, but the cmpxchg has memory ordering hints. We
give this acquire semantics.
NOTE: The unlock in libc_r is implemented by a "normal" assign
statement. This is not correct on ia64 due to the memory ordering
characteristics of the architecture. We need release semantics
for an unlock.
Revision Changes Path
1.2 +3 -2 src/lib/libc_r/arch/ia64/_atomic_lock.S
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