• Sowmini Varadhan's avatar
    neigh: Really delete an arp/neigh entry on "ip neigh delete" or "arp -d" · 5071034e
    Sowmini Varadhan authored
    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: default avatarSowmini Varadhan <sowmini.varadhan@oracle.com>
    Reviewed-by: default avatarJulian Anastasov <ja@ssi.bg>
    Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
    5071034e
neighbour.h 14.5 KB