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Date: Sun, 03 Dec 2000 06:55:32 -0800
From: Julian Elischer <julian@elischer.org>
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To: brian@freebsd.org, archie@freebsd.org, phk@freebsd.org,
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Subject: Netgraph and SMP
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I'm trying to figure out the locking needed for SMP in Netgraph.

Here are some of the various constraints that I see. (some of theme are not just
SMP issues).

1/ can't remove modules that are being used (the base framework) or have living
nodes (other netgraph modules).
2/ Cannot remove a node if it is in use, (or in a return stack somewhere)
3/ Cannot unlink an 'edge' if someone is passing data across it.
4/ cannot use edges and nodes that are in the process of being set up or torn
down.
5/ Defered deliveries cannot be made to nodes that are being removed.
6/ Nodes cannot be completely removed if there are pending deliveries for them.

What locking schemes to otther people use for protecting intricate structures of
objects with various interconnections? The buffer cache is one example that
comes to mind, as is the routing table.

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


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