Subject: Re: [PATCH] net: avoid a pair of dst_hold()/dst_release() in ip_append_data()

From: Andi Kleen <[email-masked]>
Date: Tue, 25 Nov 2008 03:22:32 +0100

> Thinking more I believe we can do similar tricks for all TCP
> transmit traffic.

Sounds reasonable.

> 
> Packets bound to sockets never outlive those sockets (and thus
> their cached routes) unless we skb_orphan().
> 
> The only not covered case is where the socket cached route
> is reset or changed.  We could defer the dst put until the
> transmit queue reaches a certain point, kind of like a retransmit
> queue RCU :-)
> 
> Just some ideas...

netfilter makes it somewhat tricky, for compatibility you would
need to reclone the route on the fly.

-Andi

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