Re: [PATCH 2/5] ipv4: Kill ip_rt_frag_needed().

From: David Miller <davem@davemloft.net>
Date: Mon, 11 Jun 2012 04:20:24 -0700 (PDT)

We need to find a way to implement this then, in such a way
that we have the route context used to send the ping packet
out.

The problem is RAW sockets right?  If so, then this is where the
fix belongs.

There is nothing preventing the RAW socket code from remembering the
last route used, as well as the flow4 key used to look it up, and
processing the PMTU message appropriately in raw_err() using that
remembered information if the flow4 key matches.