vxlan: simplify exception handling

vxlan egress path error handling has became complicated, it
need to handle IPv4 and IPv6 tunnel cases.
Earlier patch removes vlan handling from vxlan_build_skb(), so
vxlan_build_skb does not need to free skb and we can simplify
the xmit path by having single error handling for both type of
tunnels.

Signed-off-by: Pravin B Shelar <pshelar@ovn.org>
Acked-by: Jiri Benc <jbenc@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/vxlan.c b/drivers/net/vxlan.c
index 7730b33a3c3ca9aca5eeaef4ca3ff4fd9c98c3b5..40ea9e06d8d11bd829f5d8e5964cbfbaa9fd546d 100644 (file)
--- a/drivers/net/vxlan.c
+++ b/drivers/net/vxlan.c
@@ -1755,11 +1755,11 @@ static int vxlan_build_skb(struct sk_buff *skb, struct dst_entry *dst,
        /* Need space for new headers (invalidates iph ptr) */
        err = skb_cow_head(skb, min_headroom);
        if (unlikely(err))
-               goto out_free;
+               return err;
 
        err = iptunnel_handle_offloads(skb, type);
        if (err)
-               goto out_free;
+               return err;
 
        vxh = (struct vxlanhdr *) __skb_push(skb, sizeof(*vxh));
        vxh->vx_flags = VXLAN_HF_VNI;
@@ -1783,16 +1783,12 @@ static int vxlan_build_skb(struct sk_buff *skb, struct dst_entry *dst,
        if (vxflags & VXLAN_F_GPE) {
                err = vxlan_build_gpe_hdr(vxh, vxflags, skb->protocol);
                if (err < 0)
-                       goto out_free;
+                       return err;
                inner_protocol = skb->protocol;
        }
 
        skb_set_inner_protocol(skb, inner_protocol);
        return 0;
-
-out_free:
-       kfree_skb(skb);
-       return err;
 }
 
 static struct rtable *vxlan_get_route(struct vxlan_dev *vxlan,
@@ -1929,13 +1925,13 @@ static void vxlan_xmit_one(struct sk_buff *skb, struct net_device *dev,
        struct ip_tunnel_info *info;
        struct vxlan_dev *vxlan = netdev_priv(dev);
        struct sock *sk;
-       struct rtable *rt = NULL;
        const struct iphdr *old_iph;
        union vxlan_addr *dst;
        union vxlan_addr remote_ip, local_ip;
        union vxlan_addr *src;
        struct vxlan_metadata _md;
        struct vxlan_metadata *md = &_md;
+       struct dst_entry *ndst = NULL;
        __be16 src_port = 0, dst_port;
        __be32 vni, label;
        __be16 df = 0;
@@ -2011,6 +2007,7 @@ static void vxlan_xmit_one(struct sk_buff *skb, struct net_device *dev,
 
        if (dst->sa.sa_family == AF_INET) {
                struct vxlan_sock *sock4 = rcu_dereference(vxlan->vn4_sock);
+               struct rtable *rt;
 
                if (!sock4)
                        goto drop;
@@ -2032,7 +2029,8 @@ static void vxlan_xmit_one(struct sk_buff *skb, struct net_device *dev,
                        netdev_dbg(dev, "circular route to %pI4\n",
                                   &dst->sin.sin_addr.s_addr);
                        dev->stats.collisions++;
-                       goto rt_tx_error;
+                       ip_rt_put(rt);
+                       goto tx_error;
                }
 
                /* Bypass encapsulation if the destination is local */
@@ -2055,12 +2053,13 @@ static void vxlan_xmit_one(struct sk_buff *skb, struct net_device *dev,
                else if (info->key.tun_flags & TUNNEL_DONT_FRAGMENT)
                        df = htons(IP_DF);
 
+               ndst = &rt->dst;
                tos = ip_tunnel_ecn_encap(tos, old_iph, skb);
                ttl = ttl ? : ip4_dst_hoplimit(&rt->dst);
-               err = vxlan_build_skb(skb, &rt->dst, sizeof(struct iphdr),
+               err = vxlan_build_skb(skb, ndst, sizeof(struct iphdr),
                                      vni, md, flags, udp_sum);
                if (err < 0)
-                       goto xmit_tx_error;
+                       goto tx_error;
 
                udp_tunnel_xmit_skb(rt, sk, skb, src->sin.sin_addr.s_addr,
                                    dst->sin.sin_addr.s_addr, tos, ttl, df,
@@ -2068,7 +2067,6 @@ static void vxlan_xmit_one(struct sk_buff *skb, struct net_device *dev,
 #if IS_ENABLED(CONFIG_IPV6)
        } else {
                struct vxlan_sock *sock6 = rcu_dereference(vxlan->vn6_sock);
-               struct dst_entry *ndst;
                u32 rt6i_flags;
 
                ndst = vxlan6_get_route(vxlan, sock6, skb,
@@ -2080,13 +2078,13 @@ static void vxlan_xmit_one(struct sk_buff *skb, struct net_device *dev,
                        netdev_dbg(dev, "no route to %pI6\n",
                                   &dst->sin6.sin6_addr);
                        dev->stats.tx_carrier_errors++;
+                       ndst = NULL;
                        goto tx_error;
                }
 
                if (ndst->dev == dev) {
                        netdev_dbg(dev, "circular route to %pI6\n",
                                   &dst->sin6.sin6_addr);
-                       dst_release(ndst);
                        dev->stats.collisions++;
                        goto tx_error;
                }
@@ -2098,12 +2096,12 @@ static void vxlan_xmit_one(struct sk_buff *skb, struct net_device *dev,
                    !(rt6i_flags & (RTCF_BROADCAST | RTCF_MULTICAST))) {
                        struct vxlan_dev *dst_vxlan;
 
-                       dst_release(ndst);
                        dst_vxlan = vxlan_find_vni(vxlan->net, vni,
                                                   dst->sa.sa_family, dst_port,
                                                   vxlan->flags);
                        if (!dst_vxlan)
                                goto tx_error;
+                       dst_release(ndst);
                        vxlan_encap_bypass(skb, vxlan, dst_vxlan);
                        return;
                }
@@ -2116,11 +2114,9 @@ static void vxlan_xmit_one(struct sk_buff *skb, struct net_device *dev,
                skb_scrub_packet(skb, xnet);
                err = vxlan_build_skb(skb, ndst, sizeof(struct ipv6hdr),
                                      vni, md, flags, udp_sum);
-               if (err < 0) {
-                       dst_release(ndst);
-                       dev->stats.tx_errors++;
-                       return;
-               }
+               if (err < 0)
+                       goto tx_error;
+
                udp_tunnel6_xmit_skb(ndst, sk, skb, dev,
                                     &src->sin6.sin6_addr,
                                     &dst->sin6.sin6_addr, tos, ttl,
@@ -2132,17 +2128,13 @@ static void vxlan_xmit_one(struct sk_buff *skb, struct net_device *dev,
 
 drop:
        dev->stats.tx_dropped++;
-       goto tx_free;
+       dev_kfree_skb(skb);
+       return;
 
-xmit_tx_error:
-       /* skb is already freed. */
-       skb = NULL;
-rt_tx_error:
-       ip_rt_put(rt);
 tx_error:
+       dst_release(ndst);
        dev->stats.tx_errors++;
-tx_free:
-       dev_kfree_skb(skb);
+       kfree_skb(skb);
 }
 
 /* Transmit local packets over Vxlan