Re: [PATCH net-next 03/14] gtp: Call common functions to get tunnel routes and add dst_cache

On Mon, Sep 18, 2017 at 9:17 PM, David Miller [off-list ref] wrote:

From: Tom Herbert <redacted>
Date: Mon, 18 Sep 2017 17:38:53 -0700

quoted

Call ip_tunnel_get_route and dst_cache to pdp context which should
improve performance by obviating the need to perform a route lookup
on every packet.

Signed-off-by: Tom Herbert <redacted>

Not caused by your changes, but something to think about:

quoted

-static struct rtable *ip4_route_output_gtp(struct flowi4 *fl4,
-                                        const struct sock *sk,
-                                        __be32 daddr)
-{
-     memset(fl4, 0, sizeof(*fl4));
-     fl4->flowi4_oif         = sk->sk_bound_dev_if;
-     fl4->daddr              = daddr;
-     fl4->saddr              = inet_sk(sk)->inet_saddr;
-     fl4->flowi4_tos         = RT_CONN_FLAGS(sk);
-     fl4->flowi4_proto       = sk->sk_protocol;
-
-     return ip_route_output_key(sock_net(sk), fl4);
-}

This and the new dst caching code ignores any source address selection
done by ip_route_output_key() or the new tunnel route lookup helpers.

Either source address selection should be respected, or if saddr will
never be modified by a route lookup for some specific reason here,
that should be documented.

Yes, I noticed that. In this case the source address is intended to be
taken bound on the socket which would imply we aren't interested in
source address selection.

Tom