xfrm: introduce helper for safe determination of mtu
skb->sk socket can be of AF_INET or AF_INET6 address family. Thus we
always have to make sure we a referring to the correct interpretation
of skb->sk.
We only depend on header defines to query the mtu, so we don't introduce
a new dependency to ipv6 by this change.
Cc: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
diff --git a/include/net/route.h b/include/net/route.h
index 2ea40c1..afdeeb5 100644
--- a/include/net/route.h
+++ b/include/net/route.h
@@ -317,4 +317,12 @@
return hoplimit;
}
+static inline int ip_skb_dst_mtu(struct sk_buff *skb)
+{
+ struct inet_sock *inet = skb->sk ? inet_sk(skb->sk) : NULL;
+
+ return (inet && inet->pmtudisc == IP_PMTUDISC_PROBE) ?
+ skb_dst(skb)->dev->mtu : dst_mtu(skb_dst(skb));
+}
+
#endif /* _ROUTE_H */