net: Move free of fib_metrics to helper

Move the refcounting and potential free of dst metrics associated
with a fib entry to a helper and use it in both ipv4 and ipv6.
Signed-off-by: David Ahern <dsahern@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/ip.h

@@ -422,6 +422,12 @@ static inline unsigned int ip_skb_dst_mtu(struct sock *sk,
 
 struct dst_metrics *ip_fib_metrics_init(struct net *net, struct nlattr *fc_mx,
 					int fc_mx_len);
+static inline void ip_fib_metrics_put(struct dst_metrics *fib_metrics)
+{
+	if (fib_metrics != &dst_default_metrics &&
+	    refcount_dec_and_test(&fib_metrics->refcnt))
+		kfree(fib_metrics);
+}
 
 u32 ip_idents_reserve(u32 hash, int segs);
 void __ip_select_ident(struct net *net, struct iphdr *iph, int segs);

net/ipv4/fib_semantics.c

@@ -208,7 +208,6 @@ static void rt_fibinfo_free_cpus(struct rtable __rcu * __percpu *rtp)
 static void free_fib_info_rcu(struct rcu_head *head)
 {
 	struct fib_info *fi = container_of(head, struct fib_info, rcu);
-	struct dst_metrics *m;
 
 	change_nexthops(fi) {
 		if (nexthop_nh->nh_dev)
@@ -219,9 +218,8 @@ static void free_fib_info_rcu(struct rcu_head *head)
 		rt_fibinfo_free(&nexthop_nh->nh_rth_input);
 	} endfor_nexthops(fi);
 
-	m = fi->fib_metrics;
-	if (m != &dst_default_metrics && refcount_dec_and_test(&m->refcnt))
-		kfree(m);
+	ip_fib_metrics_put(fi->fib_metrics);
+
 	kfree(fi);
 }
 

net/ipv6/ip6_fib.c

@@ -29,6 +29,7 @@
 #include <linux/list.h>
 #include <linux/slab.h>
 
+#include <net/ip.h>
 #include <net/ipv6.h>
 #include <net/ndisc.h>
 #include <net/addrconf.h>
@@ -169,7 +170,6 @@ void fib6_info_destroy_rcu(struct rcu_head *head)
 {
 	struct fib6_info *f6i = container_of(head, struct fib6_info, rcu);
 	struct rt6_exception_bucket *bucket;
-	struct dst_metrics *m;
 
 	WARN_ON(f6i->fib6_node);
 
@@ -201,9 +201,7 @@ void fib6_info_destroy_rcu(struct rcu_head *head)
 	if (f6i->fib6_nh.nh_dev)
 		dev_put(f6i->fib6_nh.nh_dev);
 
-	m = f6i->fib6_metrics;
-	if (m != &dst_default_metrics && refcount_dec_and_test(&m->refcnt))
-		kfree(m);
+	ip_fib_metrics_put(f6i->fib6_metrics);
 
 	kfree(f6i);
 }