From mboxrd@z Thu Jan 1 00:00:00 1970 From: Marcelo Ricardo Leitner Subject: Re: [PATCH net-next 1/5] sctp: add the rhashtable apis for sctp global transport hashtable Date: Mon, 11 Jan 2016 14:33:37 -0200 Message-ID: <20160111163337.GC6074@mrl.redhat.com> References: <20151230.125046.310343849422003518.davem@davemloft.net> <20160111093210.GA23557@gondor.apana.org.au> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: David Miller , eric.dumazet@gmail.com, lucien.xin@gmail.com, netdev@vger.kernel.org, linux-sctp@vger.kernel.org, mleitner@redhat.com, vyasevic@redhat.com, daniel@iogearbox.net To: Herbert Xu Return-path: Received: from mx1.redhat.com ([209.132.183.28]:46572 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932457AbcAKQdl (ORCPT ); Mon, 11 Jan 2016 11:33:41 -0500 Content-Disposition: inline In-Reply-To: <20160111093210.GA23557@gondor.apana.org.au> Sender: netdev-owner@vger.kernel.org List-ID: On Mon, Jan 11, 2016 at 05:32:10PM +0800, Herbert Xu wrote: > David Miller wrote: > > From: Eric Dumazet > > Date: Wed, 30 Dec 2015 11:57:31 -0500 > > > >> I am against using rhashtable in SCTP (or TCP) at this stage, given the > >> number of bugs we have with it. > > > > Come on Eric, we've largely dealt with all of these problems. I haven't > > seen a serious report in a while. > > Well there is still the outstanding issue with softirq insertion > potentially failing with ENOMEM if we fail to expand the hash > table using just kmalloc. > > So if the target user does softirq insertions, I would wait until > the fix for that is ready. It does some, yes. If listening socket is not backlogged, there will be N inserts at each new association, where N is the number of IP addresses that the client is advertising. This is done on the second stage of the SCTP handshake. Not easily DoS-able as it requires receiving a packet from server and replying based on it, plus N is limited by MTU. AFAIK Xin's stress tests couldn't hit this situation of ENOMEM, btw. Thanks, Marcelo