From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Miller Subject: Re: [PATCH net-next] net: disable fragment reassembly if high_thresh is zero Date: Sun, 05 Jun 2016 22:57:40 -0400 (EDT) Message-ID: <20160605.225740.668676557934559956.davem@davemloft.net> References: <20160602203318.1CF6FA0E60@unicorn.suse.cz> Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, kuznet@ms2.inr.ac.ru, jmorris@namei.org, yoshfuji@linux-ipv6.org, kaber@trash.net To: mkubecek@suse.cz Return-path: Received: from shards.monkeyblade.net ([149.20.54.216]:37577 "EHLO shards.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752010AbcFFC5o (ORCPT ); Sun, 5 Jun 2016 22:57:44 -0400 In-Reply-To: <20160602203318.1CF6FA0E60@unicorn.suse.cz> Sender: netdev-owner@vger.kernel.org List-ID: From: Michal Kubecek Date: Fri, 27 May 2016 17:53:52 +0200 > Before commit 6d7b857d541e ("net: use lib/percpu_counter API for > fragmentation mem accounting"), setting the reassembly high threshold > to 0 prevented fragment reassembly as first fragment would be always > evicted before second could be added to the queue. While inefficient, > some users apparently relied on this method. > > Since the commit mentioned above, a percpu counter is used for > reassembly memory accounting and high batch size avoids taking slow path > in most common scenarios. As a result, a whole full sized packet can be > reassembled without the percpu counter's main counter changing its value > so that even with high_thresh set to 0, fragmented packets can be still > reassembled and processed. > > Add explicit check preventing reassembly if high threshold is zero. > > Signed-off-by: Michal Kubecek Applied, thanks.