Date: Mon, 11 Dec 2000 06:10:19 -0800 From: Julian Elischer <julian@elischer.org> To: Alfred Perlstein <bright@wintelcom.net> Cc: bmilekic@freebsd.org, net@freebsd.org Subject: Re: Abusing m_ext for a worthy goal. Message-ID: <3A34E04B.D93AFCB@elischer.org> References: <20001211014837.W16205@fw.wintelcom.net>
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Alfred Perlstein wrote:
>
> Ok, part of the mp cleanup got me looking at af_unix sockets.
>
> Here's the deal, descriptors can be called "in-flight" meaning they
> have been passed from one application to another via
> CMG_DATA but not picked up on the other side yet.
>
> The kernel does a bunch of hokey stuff to garbage collect them.
Check wih kirk as he always uses this as an example in his class
of something that is tricky..
>
> Instead of doing that I'd like to abuse MEXTADD to setup a callback
> to remove the references automagicaly when the mbuf it free'd.
>
> Here's the problem:
>
> I want to use the mbuf clusters, I don't want to use any special
> external storage. I want my callback to free the cluster.
>
> Any hints on how to do this?
>
> here's what I have so far:
>
> MEXTADD(control, mtod(control, char *), control->m_len, unp_mbfree,
> cm, M_RDONLY, EXT_CMSG_DATA);
>
> control is a mbuf with a cluster attached the has fd's written in it.
> cm is a pointer to the mbuf cluster.
>
> static void
> unp_mbfree(caddr_t mm, void *claddr)
> {
> struct mbuf *m = (struct mbuf *)mm;
>
> unp_scan(m, unp_discard);
> _MCLFREE(claddr);
> }
>
> does this look right? would you like to abstract the mbuf
> clusters further before i started using the _ macros?
>
> --
> -Alfred Perlstein - [bright@wintelcom.net|alfred@freebsd.org]
> "I have the heart of a child; I keep it in a jar on my desk."
>
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--
__--_|\ Julian Elischer
/ \ julian@elischer.org
( OZ ) World tour 2000
---> X_.---._/ presently in: Budapest
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