[PATCH net-next 7/9] nfp: flower: extract ipv4 udp tunnel ttl from route

[Jakub Kicinski]

From: John Hurley <john.hur...@netronome.com>

Previously the ttl for ipv4 udp tunnels was set to the namespace default.
Modify this to attempt to extract the ttl from a full route lookup on the
tunnel destination. If this is not possible then resort to the default.

Signed-off-by: John Hurley <john.hur...@netronome.com>
Reviewed-by: Jakub Kicinski <jakub.kicin...@netronome.com>
Reviewed-by: Simon Horman <simon.hor...@netronome.com>
---
 .../ethernet/netronome/nfp/flower/action.c    | 19 ++++++++++++++++++-
 1 file changed, 18 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/netronome/nfp/flower/action.c 
b/drivers/net/ethernet/netronome/nfp/flower/action.c
index 61ba8d4f99f1..d421b7fbce96 100644
--- a/drivers/net/ethernet/netronome/nfp/flower/action.c
+++ b/drivers/net/ethernet/netronome/nfp/flower/action.c
@@ -236,9 +236,12 @@ nfp_fl_set_ipv4_udp_tun(struct nfp_fl_set_ipv4_udp_tun 
*set_tun,
        size_t act_size = sizeof(struct nfp_fl_set_ipv4_udp_tun);
        struct ip_tunnel_info *ip_tun = tcf_tunnel_info(action);
        u32 tmp_set_ip_tun_type_index = 0;
+       struct flowi4 flow = {};
        /* Currently support one pre-tunnel so index is always 0. */
        int pretun_idx = 0;
+       struct rtable *rt;
        struct net *net;
+       int err;
 
        if (ip_tun->options_len)
                return -EOPNOTSUPP;
@@ -255,7 +258,21 @@ nfp_fl_set_ipv4_udp_tun(struct nfp_fl_set_ipv4_udp_tun 
*set_tun,
 
        set_tun->tun_type_index = cpu_to_be32(tmp_set_ip_tun_type_index);
        set_tun->tun_id = ip_tun->key.tun_id;
-       set_tun->ttl = net->ipv4.sysctl_ip_default_ttl;
+
+       /* Do a route lookup to determine ttl - if fails then use default.
+        * Note that CONFIG_INET is a requirement of CONFIG_NET_SWITCHDEV so
+        * must be defined here.
+        */
+       flow.daddr = ip_tun->key.u.ipv4.dst;
+       flow.flowi4_proto = IPPROTO_UDP;
+       rt = ip_route_output_key(net, &flow);
+       err = PTR_ERR_OR_ZERO(rt);
+       if (!err) {
+               set_tun->ttl = ip4_dst_hoplimit(&rt->dst);
+               ip_rt_put(rt);
+       } else {
+               set_tun->ttl = net->ipv4.sysctl_ip_default_ttl;
+       }
 
        /* Complete pre_tunnel action. */
        pre_tun->ipv4_dst = ip_tun->key.u.ipv4.dst;
-- 
2.17.1