lwtunnel: add options process for cmp_encap

When comparing two tun_info, dst_cache member should have been skipped,
as dst_cache is a per cpu pointer and they are always different values
even in two tun_info with the same keys.

So this patch is to skip dst_cache member and compare the key, mode and
options_len only. For the future opts setting support, also to compare
options.

Fixes: 2d798499 ("lwtunnel: ip tunnel: fix multiple routes with different encap")
Signed-off-by: Xin Long <lucien.xin@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv4/ip_tunnel_core.c

@@ -315,8 +315,14 @@ static int ip_tun_encap_nlsize(struct lwtunnel_state *lwtstate)
 
 static int ip_tun_cmp_encap(struct lwtunnel_state *a, struct lwtunnel_state *b)
 {
-	return memcmp(lwt_tun_info(a), lwt_tun_info(b),
-		      sizeof(struct ip_tunnel_info));
+	struct ip_tunnel_info *info_a = lwt_tun_info(a);
+	struct ip_tunnel_info *info_b = lwt_tun_info(b);
+
+	return memcmp(info_a, info_b, sizeof(info_a->key)) ||
+	       info_a->mode != info_b->mode ||
+	       info_a->options_len != info_b->options_len ||
+	       memcmp(ip_tunnel_info_opts(info_a),
+		      ip_tunnel_info_opts(info_b), info_a->options_len);
 }
 
 static const struct lwtunnel_encap_ops ip_tun_lwt_ops = {