On Mon, Oct 30, 2017 at 09:29:34AM +0800, Yi Yang wrote:
[...]

+int nsh_pop(struct sk_buff *skb)
+{
+	struct nshhdr *nh;
+	size_t length;
+	__be16 inner_proto;
+
+	if (!pskb_may_pull(skb, NSH_BASE_HDR_LEN))
+		return -ENOMEM;
+	nh = (struct nshhdr *)(skb->data);
+	length = nsh_hdr_len(nh);
+	if (!pskb_may_pull(skb, length))
+		return -ENOMEM;
+
+	nh = (struct nshhdr *)(skb->data);
+	inner_proto = tun_p_to_eth_p(nh->np);

If you fetch inner_proto before the second pskb_may_pull then there is
no need to reload the nh pointer as you won't use it later.

+	if (!inner_proto)
+		return -EAFNOSUPPORT;
+
+	length = nsh_hdr_len(nh);

You already have the length from above. No need to get it again.

+	skb_pull(skb, length);
+	skb_reset_mac_header(skb);
+	skb_reset_network_header(skb);
+	skb_reset_mac_len(skb);
+	skb->protocol = inner_proto;
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(nsh_pop);

[...]

+static int nsh_key_put_from_nlattr(const struct nlattr *attr,
+				   struct sw_flow_match *match, bool is_mask,
+				   bool is_push_nsh, bool log)
+{
+	struct nlattr *a;
+	int rem;
+	bool has_base = false;
+	bool has_md1 = false;
+	bool has_md2 = false;
+	u8 mdtype = 0;
+	int mdlen = 0;
+
+	if (WARN_ON(is_push_nsh && is_mask))
+		return -EINVAL;

OVS_NLERR() is probably more appropriate.

+
+	nla_for_each_nested(a, attr, rem) {
+		int type = nla_type(a);
+		int i;
+

[...]