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Date:      Wed, 13 Dec 2000 13:45:11 -0800
From:      Julian Elischer <julian@elischer.org>
To:        John Baldwin <jhb@FreeBSD.org>
Cc:        Bosko Milekic <bmilekic@FreeBSD.org>, cvs-all@FreeBSD.org, cvs-committers@FreeBSD.org
Subject:   Re: cvs commit: src/sys/sys mbuf.h
Message-ID:  <3A37EDE7.4E2A2F52@elischer.org>
References:  <XFMail.001213105244.jhb@FreeBSD.org>

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John Baldwin wrote:
> 
> On 13-Dec-00 Bosko Milekic wrote:
> > bmilekic    2000/12/12 21:13:03 PST
> >
> >   Modified files:
> >     sys/sys              mbuf.h
> >   Log:
> >   Eliminate a race in MEXTFREE(). The reference counter decrement and test
> >   was not atomic. We now make sure that we free the ext buf if the reference
> >   count is about to reach 0 but also make sure that nobody else has done it
> >   before us.
> >
> >   While I'm here, change refcnt to u_int (from long). This fixes a compiler
> >   warning regarding use of atomic_cmpset_long on i386.
> 
> If you are using atomic_cmpset_long, then use u_long for the refcount instead
> of u_int please.  Eitehr that, or use atomic_cmpset_int.

looking  at the alpha code it looks like possibly cmpset instructions have to be 
synthesised on alpha and might be quite expensive..  what are the facts in 
this regard?

> 
> --
> 
> John Baldwin <jhb@FreeBSD.org> -- http://www.FreeBSD.org/~jhb/
> PGP Key: http://www.Baldwin.cx/~john/pgpkey.asc
> "Power Users Use the Power to Serve!"  -  http://www.FreeBSD.org/

-- 
      __--_|\  Julian Elischer
     /       \ julian@elischer.org
    (   OZ    ) World tour 2000
---> X_.---._/  presently in:  Budapest
            v


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