ipv4: use separate genid for next hop exceptions

commit 13d82bf5 (ipv4: Fix flushing of cached routing informations)
added the support to flush learned pmtu information.

However, using rt_genid is quite heavy as it is bumped on route
add/change and multicast events amongst other places. These can
happen quite often, especially if using dynamic routing protocols.

While this is ok with routes (as they are just recreated locally),
the pmtu information is learned from remote systems and the icmp
notification can come with long delays. It is worthy to have separate
genid to avoid excessive pmtu resets.

Cc: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: Timo Teräs <timo.teras@iki.fi>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 11 insertions, 0 deletions

diff --git a/include/net/net_namespace.h b/include/net/net_namespace.h
index b17697827482..495bc57f292c 100644
--- a/include/net/net_namespace.h
+++ b/include/net/net_namespace.h
@@ -118,6 +118,7 @@ struct net {
         struct netns_ipvs       *ipvs;
         struct sock             *diag_nlsk;
         atomic_t                rt_genid;
+        atomic_t                fnhe_genid;
 };
 
 /*
@@ -340,4 +341,14 @@ static inline void rt_genid_bump(struct net *net)
         atomic_inc(&net->rt_genid);
 }
 
+static inline int fnhe_genid(struct net *net)
+{
+        return atomic_read(&net->fnhe_genid);
+}
+
+static inline void fnhe_genid_bump(struct net *net)
+{
+        atomic_inc(&net->fnhe_genid);
+}
+
 #endif /* __NET_NET_NAMESPACE_H */