net: Move mtu handling down to the protocol depended handlers

We move all mtu handling from dst_mtu() down to the protocol
layer. So each protocol can implement the mtu handling in
a different manner.

Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 9 insertions, 2 deletions

diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 76645d7077f..3399dd32628 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -157,7 +157,9 @@ static struct dst_ops ip6_dst_ops_template = {
 
 static unsigned int ip6_blackhole_mtu(const struct dst_entry *dst)
 {
-        return dst->dev->mtu;
+        unsigned int mtu = dst_metric_raw(dst, RTAX_MTU);
+
+        return mtu ? : dst->dev->mtu;
 }
 
 static void ip6_rt_blackhole_update_pmtu(struct dst_entry *dst, u32 mtu)
@@ -1043,8 +1045,13 @@ static unsigned int ip6_default_advmss(const struct dst_entry *dst)
 
 static unsigned int ip6_mtu(const struct dst_entry *dst)
 {
-        unsigned int mtu = IPV6_MIN_MTU;
         struct inet6_dev *idev;
+        unsigned int mtu = dst_metric_raw(dst, RTAX_MTU);
+
+        if (mtu)
+                return mtu;
+
+        mtu = IPV6_MIN_MTU;
 
         rcu_read_lock();
         idev = __in6_dev_get(dst->dev);