[PATCH v5 net-next 03/12] gtp: Call common functions to get tunnel routes and add dst_cache

[Tom Herbert]

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 <t...@quantonium.net>
---
 drivers/net/gtp.c | 62 +++++++++++++++++++++++++++++++------------------------
 1 file changed, 35 insertions(+), 27 deletions(-)

diff --git a/drivers/net/gtp.c b/drivers/net/gtp.c
index f38e32a7ec9c..6dabd605607c 100644
--- a/drivers/net/gtp.c
+++ b/drivers/net/gtp.c
@@ -63,6 +63,8 @@ struct pdp_ctx {
 
        atomic_t                tx_seq;
        struct rcu_head         rcu_head;
+
+       struct dst_cache        dst_cache;
 };
 
 /* One instance of the GTP device. */
@@ -379,20 +381,6 @@ static void gtp_dev_uninit(struct net_device *dev)
        free_percpu(dev->tstats);
 }
 
-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);
-}
-
 static inline void gtp0_push_header(struct sk_buff *skb, struct pdp_ctx *pctx)
 {
        int payload_len = skb->len;
@@ -479,6 +467,8 @@ static int gtp_build_skb_ip4(struct sk_buff *skb, struct 
net_device *dev,
        struct rtable *rt;
        struct flowi4 fl4;
        struct iphdr *iph;
+       struct sock *sk;
+       __be32 saddr;
        __be16 df;
        int mtu;
 
@@ -498,19 +488,30 @@ static int gtp_build_skb_ip4(struct sk_buff *skb, struct 
net_device *dev,
        }
        netdev_dbg(dev, "found PDP context %p\n", pctx);
 
-       rt = ip4_route_output_gtp(&fl4, pctx->sk, pctx->peer_addr_ip4.s_addr);
-       if (IS_ERR(rt)) {
-               netdev_dbg(dev, "no route to SSGN %pI4\n",
-                          &pctx->peer_addr_ip4.s_addr);
-               dev->stats.tx_carrier_errors++;
-               goto err;
-       }
+       sk = pctx->sk;
+       saddr = inet_sk(sk)->inet_saddr;
 
-       if (rt->dst.dev == dev) {
-               netdev_dbg(dev, "circular route to SSGN %pI4\n",
-                          &pctx->peer_addr_ip4.s_addr);
-               dev->stats.collisions++;
-               goto err_rt;
+       /* Source address returned by route lookup is ignored since
+        * we get the address from a socket.
+        */
+       rt = ip_tunnel_get_route(dev, skb, sk->sk_protocol,
+                                sk->sk_bound_dev_if, RT_CONN_FLAGS(sk),
+                                pctx->peer_addr_ip4.s_addr, &saddr,
+                                pktinfo->gtph_port, pktinfo->gtph_port,
+                                &pctx->dst_cache, NULL);
+
+       if (IS_ERR(rt)) {
+               if (rt == ERR_PTR(-ELOOP)) {
+                       netdev_dbg(dev, "circular route to SSGN %pI4\n",
+                                  &pctx->peer_addr_ip4.s_addr);
+                       dev->stats.collisions++;
+                       goto err_rt;
+               } else {
+                       netdev_dbg(dev, "no route to SSGN %pI4\n",
+                                  &pctx->peer_addr_ip4.s_addr);
+                       dev->stats.tx_carrier_errors++;
+                       goto err;
+               }
        }
 
        skb_dst_drop(skb);
@@ -543,7 +544,7 @@ static int gtp_build_skb_ip4(struct sk_buff *skb, struct 
net_device *dev,
                goto err_rt;
        }
 
-       gtp_set_pktinfo_ipv4(pktinfo, pctx->sk, iph, pctx, rt, &fl4, dev);
+       gtp_set_pktinfo_ipv4(pktinfo, sk, iph, pctx, rt, &fl4, dev);
        gtp_push_header(skb, pktinfo);
 
        return 0;
@@ -917,6 +918,7 @@ static int ipv4_pdp_add(struct gtp_dev *gtp, struct sock 
*sk,
        struct pdp_ctx *pctx;
        bool found = false;
        __be32 ms_addr;
+       int err;
 
        ms_addr = nla_get_be32(info->attrs[GTPA_MS_ADDRESS]);
        hash_ms = ipv4_hashfn(ms_addr) % gtp->hash_size;
@@ -951,6 +953,12 @@ static int ipv4_pdp_add(struct gtp_dev *gtp, struct sock 
*sk,
        if (pctx == NULL)
                return -ENOMEM;
 
+       err = dst_cache_init(&pctx->dst_cache, GFP_KERNEL);
+       if (err) {
+               kfree(pctx);
+               return err;
+       }
+
        sock_hold(sk);
        pctx->sk = sk;
        pctx->dev = gtp->dev;
-- 
2.11.0