From 4b2a2bfeb3f056461a90bd621e8bd7d03fa47f60 Mon Sep 17 00:00:00 2001 From: David Ahern Date: Wed, 1 May 2019 18:18:42 -0700 Subject: [PATCH] neighbor: Call __ipv4_neigh_lookup_noref in neigh_xmit Commit cd9ff4de0107 changed the key for IFF_POINTOPOINT devices to INADDR_ANY but neigh_xmit which is used for MPLS encapsulations was not updated to use the altered key. The result is that every packet Tx does a lookup on the gateway address which does not find an entry, a new one is created only to find the existing one in the table right before the insert since arp_constructor was updated to reset the primary key. This is seen in the allocs and destroys counters: ip -s -4 ntable show | head -10 | grep alloc which increase for each packet showing the unnecessary overhread. Fix by having neigh_xmit use __ipv4_neigh_lookup_noref for NEIGH_ARP_TABLE. Fixes: cd9ff4de0107 ("ipv4: Make neigh lookup keys for loopback/point-to-point devices be INADDR_ANY") Reported-by: Alan Maguire Signed-off-by: David Ahern Tested-by: Alan Maguire Signed-off-by: David S. Miller --- net/core/neighbour.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/net/core/neighbour.c b/net/core/neighbour.c index aff051e5521d..9b9da5142613 100644 --- a/net/core/neighbour.c +++ b/net/core/neighbour.c @@ -31,6 +31,7 @@ #include #include #include +#include #include #include #include @@ -2984,7 +2985,13 @@ int neigh_xmit(int index, struct net_device *dev, if (!tbl) goto out; rcu_read_lock_bh(); - neigh = __neigh_lookup_noref(tbl, addr, dev); + if (index == NEIGH_ARP_TABLE) { + u32 key = *((u32 *)addr); + + neigh = __ipv4_neigh_lookup_noref(dev, key); + } else { + neigh = __neigh_lookup_noref(tbl, addr, dev); + } if (!neigh) neigh = __neigh_create(tbl, addr, dev, false); err = PTR_ERR(neigh); -- 2.34.1