lwtunnel: Pass encap and encap type attributes to lwtunnel_fill_encap

Currently, lwtunnel_fill_encap hardcodes the encap and encap type
attributes as RTA_ENCAP and RTA_ENCAP_TYPE, respectively. The nexthop
objects want to re-use this code but the encap attributes passed to
userspace as NHA_ENCAP and NHA_ENCAP_TYPE. Since that is the only
difference, change lwtunnel_fill_encap to take the attribute type as
an input.

Signed-off-by: David Ahern <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

include/net/lwtunnel.h

···
 			 unsigned int family, const void *cfg,
 			 struct lwtunnel_state **lws,
 			 struct netlink_ext_ack *extack);
-int lwtunnel_fill_encap(struct sk_buff *skb,
-			struct lwtunnel_state *lwtstate);
+int lwtunnel_fill_encap(struct sk_buff *skb, struct lwtunnel_state *lwtstate,
+			int encap_attr, int encap_type_attr);
 int lwtunnel_get_encap_size(struct lwtunnel_state *lwtstate);
 struct lwtunnel_state *lwtunnel_state_alloc(int hdr_len);
 int lwtunnel_cmp_encap(struct lwtunnel_state *a, struct lwtunnel_state *b);
···
 }
 
 static inline int lwtunnel_fill_encap(struct sk_buff *skb,
-				      struct lwtunnel_state *lwtstate)
+				      struct lwtunnel_state *lwtstate,
+				      int encap_attr, int encap_type_attr)
 {
 	return 0;
 }

net/core/lwtunnel.c

···
 }
 EXPORT_SYMBOL_GPL(lwtstate_free);
 
-int lwtunnel_fill_encap(struct sk_buff *skb, struct lwtunnel_state *lwtstate)
+int lwtunnel_fill_encap(struct sk_buff *skb, struct lwtunnel_state *lwtstate,
+			int encap_attr, int encap_type_attr)
 {
 	const struct lwtunnel_encap_ops *ops;
 	struct nlattr *nest;
···
 	    lwtstate->type > LWTUNNEL_ENCAP_MAX)
 		return 0;
 
-	nest = nla_nest_start(skb, RTA_ENCAP);
+	nest = nla_nest_start(skb, encap_attr);
 	if (!nest)
 		return -EMSGSIZE;
 
···
 	if (ret)
 		goto nla_put_failure;
 	nla_nest_end(skb, nest);
-	ret = nla_put_u16(skb, RTA_ENCAP_TYPE, lwtstate->type);
+	ret = nla_put_u16(skb, encap_type_attr, lwtstate->type);
 	if (ret)
 		goto nla_put_failure;
 

net/ipv4/fib_semantics.c

···
 		goto nla_put_failure;
 
 	if (nhc->nhc_lwtstate &&
-	    lwtunnel_fill_encap(skb, nhc->nhc_lwtstate) < 0)
+	    lwtunnel_fill_encap(skb, nhc->nhc_lwtstate,
+				RTA_ENCAP, RTA_ENCAP_TYPE) < 0)
 		goto nla_put_failure;
 
 	return 0;