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Date:      Tue, 21 May 2002 13:43:18 -0700
From:      Alfred Perlstein <bright@mu.org>
To:        Archie Cobbs <archie@dellroad.org>
Cc:        freebsd-arch@freebsd.org
Subject:   Re: question about atomic.h
Message-ID:  <20020521204318.GJ54960@elvis.mu.org>
In-Reply-To: <200205212027.g4LKRD058396@arch20m.dellroad.org>
References:  <200205212027.g4LKRD058396@arch20m.dellroad.org>

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* Archie Cobbs <archie@dellroad.org> [020521 13:30] wrote:
> 
> With atomic_subtract_int() returning void, there's no way to do
> that without acquiring the mutex, because you can't atomically
> decrement *and* read the reference count.

Check the mbuf subsystem for the way they do the atomic "decerement
and let me know if it went to zero" operation.

it's something like atomic_int_acq or something. :)

-- 
-Alfred Perlstein [alfred@freebsd.org]
'Instead of asking why a piece of software is using "1970s technology,"
 start asking why software is ignoring 30 years of accumulated wisdom.'
Tax deductible donations for FreeBSD: http://www.freebsdfoundation.org/

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