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, 3 insertions, 1 deletions

diff --git a/net/xfrm/xfrm_policy.c b/net/xfrm/xfrm_policy.c
index b8be51eb7e29..2118d6446630 100644
--- a/net/xfrm/xfrm_policy.c
+++ b/net/xfrm/xfrm_policy.c
@@ -2384,7 +2384,9 @@ static unsigned int xfrm_default_advmss(const struct dst_entry *dst)
 
 static unsigned int xfrm_mtu(const struct dst_entry *dst)
 {
-        return dst_mtu(dst->path);
+        unsigned int mtu = dst_metric_raw(dst, RTAX_MTU);
+
+        return mtu ? : dst_mtu(dst->path);
 }
 
 static struct neighbour *xfrm_neigh_lookup(const struct dst_entry *dst, const void *daddr)