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Date:      Tue, 12 Dec 2000 08:39:27 -0800 (PST)
From:      John Baldwin <jhb@FreeBSD.org>
To:        Alfred Perlstein <bright@wintelcom.net>
Cc:        jasone@FreeBSD.org, net@FreeBSD.org, Bosko Milekic <bmilekic@technokratis.com>
Subject:   RE: MEXT_IS_REF broken.
Message-ID:  <XFMail.001212083927.jhb@FreeBSD.org>
In-Reply-To: <20001212014429.Y16205@fw.wintelcom.net>

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On 12-Dec-00 Alfred Perlstein wrote:
> grr...
> 
> considering this:
> 
>#define MEXT_IS_REF(m) ((m)->m_ext.ref_cnt->refcnt > 1)
> 
>#define MEXT_REM_REF(m) do {                        \
>     KASSERT((m)->m_ext.ref_cnt->refcnt > 0, ("m_ext refcnt < 0"));  \
>     atomic_subtract_long(&((m)->m_ext.ref_cnt->refcnt), 1);     \
> } while(0)
> 
> this:
> 
>#define MEXTFREE(m) do {                        \
>     struct mbuf *_mmm = (m);                    \
>                                     \
>     if (MEXT_IS_REF(_mmm))                      \
>         MEXT_REM_REF(_mmm);                 \
> 
>  
> is not mpsafe.  we _NEED_ some type that allows atomic dec and test
> for 0.

http://www.FreeBSD.org/~jhb/patches/refcount.patch

> thanks,
> -Alfred

-- 

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/


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