From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Miller Subject: Re: [PATCH V5 net-next] neigh: Really delete an arp/neigh entry on "ip neigh delete" or "arp -d" Date: Sun, 04 Jun 2017 21:37:33 -0400 (EDT) Message-ID: <20170604.213733.1423109980903333523.davem@davemloft.net> References: <1496419309-91478-1-git-send-email-sowmini.varadhan@oracle.com> Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org, stephen@networkplumber.org, ja@ssi.bg To: sowmini.varadhan@oracle.com Return-path: Received: from shards.monkeyblade.net ([184.105.139.130]:54244 "EHLO shards.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751193AbdFEBhf (ORCPT ); Sun, 4 Jun 2017 21:37:35 -0400 In-Reply-To: <1496419309-91478-1-git-send-email-sowmini.varadhan@oracle.com> Sender: netdev-owner@vger.kernel.org List-ID: From: Sowmini Varadhan Date: Fri, 2 Jun 2017 09:01:49 -0700 > 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 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 > Reviewed-by: Julian Anastasov Applied, thank you.