[RTNETLINK]: Add rtnl_put_cacheinfo() to unify some code

IPv4, IPv6, and DECNet all use struct rta_cacheinfo in a similiar
way, therefore rtnl_put_cacheinfo() is added to reuse code.

Signed-off-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index ee00b65..9f3924c 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -2629,7 +2629,8 @@
 	struct rtable *rt = (struct rtable*)skb->dst;
 	struct rtmsg *r;
 	struct nlmsghdr *nlh;
-	struct rta_cacheinfo ci;
+	long expires;
+	u32 id = 0, ts = 0, tsage = 0, error;
 
 	nlh = nlmsg_put(skb, pid, seq, event, sizeof(*r), flags);
 	if (nlh == NULL)
@@ -2676,20 +2677,13 @@
 	if (rtnetlink_put_metrics(skb, rt->u.dst.metrics) < 0)
 		goto nla_put_failure;
 
-	ci.rta_lastuse	= jiffies_to_clock_t(jiffies - rt->u.dst.lastuse);
-	ci.rta_used	= rt->u.dst.__use;
-	ci.rta_clntref	= atomic_read(&rt->u.dst.__refcnt);
-	if (rt->u.dst.expires)
-		ci.rta_expires = jiffies_to_clock_t(rt->u.dst.expires - jiffies);
-	else
-		ci.rta_expires = 0;
-	ci.rta_error	= rt->u.dst.error;
-	ci.rta_id	= ci.rta_ts = ci.rta_tsage = 0;
+	error = rt->u.dst.error;
+	expires = rt->u.dst.expires ? rt->u.dst.expires - jiffies : 0;
 	if (rt->peer) {
-		ci.rta_id = rt->peer->ip_id_count;
+		id = rt->peer->ip_id_count;
 		if (rt->peer->tcp_ts_stamp) {
-			ci.rta_ts = rt->peer->tcp_ts;
-			ci.rta_tsage = xtime.tv_sec - rt->peer->tcp_ts_stamp;
+			ts = rt->peer->tcp_ts;
+			tsage = xtime.tv_sec - rt->peer->tcp_ts_stamp;
 		}
 	}
 
@@ -2708,7 +2702,7 @@
 				} else {
 					if (err == -EMSGSIZE)
 						goto nla_put_failure;
-					ci.rta_error = err;
+					error = err;
 				}
 			}
 		} else
@@ -2716,7 +2710,9 @@
 			NLA_PUT_U32(skb, RTA_IIF, rt->fl.iif);
 	}
 
-	NLA_PUT(skb, RTA_CACHEINFO, sizeof(ci), &ci);
+	if (rtnl_put_cacheinfo(skb, &rt->u.dst, id, ts, tsage,
+			       expires, error) < 0)
+		goto nla_put_failure;
 
 	return nlmsg_end(skb, nlh);