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authorSowmini Varadhan <sowmini.varadhan@oracle.com>2017-06-02 09:01:49 -0700
committerDavid S. Miller <davem@davemloft.net>2017-06-04 21:37:18 -0400
commit5071034e4af709d6783b7d105dc296a5cc84739b (patch)
tree1817b75dea97eee82647e69c498c35c4d886ece3 /net/ipv4/arp.c
parent030a89028db07a7987f1f3bd6ee43114e36f5060 (diff)
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neigh: Really delete an arp/neigh entry on "ip neigh delete" or "arp -d"
The command # arp -s 62.2.0.1 a:b:c:d:e:f dev eth2 adds an entry like the following (listed by "arp -an") ? (62.2.0.1) at 0a:0b:0c:0d:0e:0f [ether] PERM on eth2 but the symmetric deletion command # arp -i eth2 -d 62.2.0.1 does not remove the PERM entry from the table, and instead leaves behind ? (62.2.0.1) at <incomplete> on eth2 The reason is that there is a refcnt of 1 for the arp_tbl itself (neigh_alloc starts off the entry with a refcnt of 1), thus the neigh_release() call from arp_invalidate() will (at best) just decrement the ref to 1, but will never actually free it from the table. To fix this, we need to do something like neigh_forced_gc: if the refcnt is 1 (i.e., on the table's ref), remove the entry from the table and free it. This patch refactors and shares common code between neigh_forced_gc and the newly added neigh_remove_one. A similar issue exists for IPv6 Neighbor Cache entries, and is fixed in a similar manner by this patch. Signed-off-by: Sowmini Varadhan <sowmini.varadhan@oracle.com> Reviewed-by: Julian Anastasov <ja@ssi.bg> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4/arp.c')
-rw-r--r--net/ipv4/arp.c4
1 files changed, 4 insertions, 0 deletions
diff --git a/net/ipv4/arp.c b/net/ipv4/arp.c
index e9f3386a528b..a651c53260ec 100644
--- a/net/ipv4/arp.c
+++ b/net/ipv4/arp.c
@@ -1113,13 +1113,17 @@ static int arp_invalidate(struct net_device *dev, __be32 ip)
{
struct neighbour *neigh = neigh_lookup(&arp_tbl, &ip, dev);
int err = -ENXIO;
+ struct neigh_table *tbl = &arp_tbl;
if (neigh) {
if (neigh->nud_state & ~NUD_NOARP)
err = neigh_update(neigh, NULL, NUD_FAILED,
NEIGH_UPDATE_F_OVERRIDE|
NEIGH_UPDATE_F_ADMIN, 0);
+ write_lock_bh(&tbl->lock);
neigh_release(neigh);
+ neigh_remove_one(neigh, tbl);
+ write_unlock_bh(&tbl->lock);
}
return err;