[PATCH net-next 2/3] net: gro: parse ipv6 ext headers without frag0

[Richard Gobert]

This commit utilizes a new helper function, ipv6_gro_pull_exthdrs, which
is used in ipv6_gro_receive to pull ipv6 ext headers instead of
ipv6_gso_pull_exthdrs. To use ipv6_gso_pull_exthdr, pskb_pull and
__skb_push must be used, and frag0 must be invalidated. This commit
removes unnecessary code around the call to ipv6_gso_pull_exthdrs and
enables the frag0 fast path in IPv6 packets with ext headers.

Signed-off-by: Richard Gobert <richardbgob...@gmail.com>
---
 net/ipv6/ip6_offload.c | 51 +++++++++++++++++++++++++++++++++---------
 1 file changed, 41 insertions(+), 10 deletions(-)

diff --git a/net/ipv6/ip6_offload.c b/net/ipv6/ip6_offload.c
index 0e0b5fed0995..a3b8d9127dbb 100644
--- a/net/ipv6/ip6_offload.c
+++ b/net/ipv6/ip6_offload.c
@@ -37,6 +37,40 @@
                INDIRECT_CALL_L4(cb, f2, f1, head, skb);        \
 })
 
+static int ipv6_gro_pull_exthdrs(struct sk_buff *skb, int off, int proto)
+{
+       const struct net_offload *ops = NULL;
+       struct ipv6_opt_hdr *opth;
+
+       for (;;) {
+               int len;
+
+               ops = rcu_dereference(inet6_offloads[proto]);
+
+               if (unlikely(!ops))
+                       break;
+
+               if (!(ops->flags & INET6_PROTO_GSO_EXTHDR))
+                       break;
+
+               opth = skb_gro_header(skb, off + 8, off);
+               if (unlikely(!opth))
+                       break;
+
+               len = ipv6_optlen(opth);
+
+               opth = skb_gro_header(skb, off + len, off);
+               if (unlikely(!opth))
+                       break;
+               proto = opth->nexthdr;
+
+               off += len;
+       }
+
+       skb_gro_pull(skb, off - skb_network_offset(skb));
+       return proto;
+}
+
 static int ipv6_gso_pull_exthdrs(struct sk_buff *skb, int proto)
 {
        const struct net_offload *ops = NULL;
@@ -203,28 +237,25 @@ INDIRECT_CALLABLE_SCOPE struct sk_buff 
*ipv6_gro_receive(struct list_head *head,
                goto out;
 
        skb_set_network_header(skb, off);
-       skb_gro_pull(skb, sizeof(*iph));
-       skb_set_transport_header(skb, skb_gro_offset(skb));
 
-       flush += ntohs(iph->payload_len) != skb_gro_len(skb);
+       flush += ntohs(iph->payload_len) != skb->len - hlen;
 
        proto = iph->nexthdr;
        ops = rcu_dereference(inet6_offloads[proto]);
        if (!ops || !ops->callbacks.gro_receive) {
-               pskb_pull(skb, skb_gro_offset(skb));
-               skb_gro_frag0_invalidate(skb);
-               proto = ipv6_gso_pull_exthdrs(skb, proto);
-               skb_gro_pull(skb, -skb_transport_offset(skb));
-               skb_reset_transport_header(skb);
-               __skb_push(skb, skb_gro_offset(skb));
+               proto = ipv6_gro_pull_exthdrs(skb, hlen, proto);
 
                ops = rcu_dereference(inet6_offloads[proto]);
                if (!ops || !ops->callbacks.gro_receive)
                        goto out;
 
-               iph = ipv6_hdr(skb);
+               iph = skb_gro_network_header(skb);
+       } else {
+               skb_gro_pull(skb, sizeof(*iph));
        }
 
+       skb_set_transport_header(skb, skb_gro_offset(skb));
+
        NAPI_GRO_CB(skb)->proto = proto;
 
        flush--;
-- 
2.36.1