From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jamal Hadi Salim Subject: Re: [PATCH net] netlink: fix netlink_ack with large messages Date: Sat, 09 Nov 2013 08:43:51 -0500 Message-ID: <527E3C17.1080508@mojatatu.com> References: <9333f540a9b87adbdd15e274d12a9d60994fdb34.1383850578.git.jbenc@redhat.com> <20131108.150741.966018155704146843.davem@davemloft.net> <20131109000434.GD28793@casper.infradead.org> <20131109.000012.1393414533296613338.davem@davemloft.net> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: jbenc@redhat.com, netdev@vger.kernel.org, pablo@netfilter.org To: David Miller , tgraf@suug.ch Return-path: Received: from mail-pb0-f41.google.com ([209.85.160.41]:59235 "EHLO mail-pb0-f41.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752297Ab3KINnx (ORCPT ); Sat, 9 Nov 2013 08:43:53 -0500 Received: by mail-pb0-f41.google.com with SMTP id wy17so3369486pbc.0 for ; Sat, 09 Nov 2013 05:43:53 -0800 (PST) In-Reply-To: <20131109.000012.1393414533296613338.davem@davemloft.net> Sender: netdev-owner@vger.kernel.org List-ID: On 11/09/13 00:00, David Miller wrote: > The user has the message, they gave it to us in the sendmsg() > we are responding to. We absolutely do not need to give it > to them again. > > If they care about referring to the contents of that message, they can > refer to it in their own copy and make sure they are really looking at > the same thing by comparing the sequence number in the netlink ACK to > the one they used in the netlink header they gave to the kernel in the > sendmsg() call. > > What happens now is pure duplication, and for such huge netlink > messages it's really not smart at all. > for errors, we need to give the user something back. This has been the behavior for 80 years now. Giving them a HUGE message back is rediculuos(tm). Ive had enough of SCTP doing that. We need to cap it - sort of what ICMP does. ICMP caps at 64B; something like 128B is reasonable. cheers, jamal