From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jiri Pirko Subject: Re: [PATCH] net: take care of bonding in build_skb_flow_key (v4) Date: Thu, 21 Jan 2016 09:35:06 +0100 Message-ID: <20160121083506.GA2251@nanopsycho.orion> References: <1453354378-3018-1-git-send-email-wen.gang.wang@oracle.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: netdev@vger.kernel.org, sd@queasysnail.net, jay.vosburgh@canonical.com, zyjzyj2000@gmail.com To: Wengang Wang Return-path: Received: from mail-wm0-f66.google.com ([74.125.82.66]:34940 "EHLO mail-wm0-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751037AbcAUIfJ (ORCPT ); Thu, 21 Jan 2016 03:35:09 -0500 Received: by mail-wm0-f66.google.com with SMTP id 123so9264001wmz.2 for ; Thu, 21 Jan 2016 00:35:08 -0800 (PST) Content-Disposition: inline In-Reply-To: <1453354378-3018-1-git-send-email-wen.gang.wang@oracle.com> Sender: netdev-owner@vger.kernel.org List-ID: Thu, Jan 21, 2016 at 06:32:58AM CET, wen.gang.wang@oracle.com wrote: >In a bonding setting, we determines fragment size according to MTU and >PMTU associated to the bonding master. If the slave finds the fragment >size is too big, it drops the fragment and calls ip_rt_update_pmtu(), >passing _skb_ and _pmtu_, trying to update the path MTU. >Problem is that the target device that function ip_rt_update_pmtu actually >tries to update is the slave (skb->dev), not the master. Thus since no >PMTU change happens on master, the fragment size for later packets doesn't >change so all later fragments/packets are dropped too. > >The fix is letting build_skb_flow_key() take care of the transition of >device index from bonding slave to the master. That makes the master become >the target device that ip_rt_update_pmtu tries to update PMTU to. > >Signed-off-by: Wengang Wang >--- > net/ipv4/route.c | 9 +++++++++ > 1 file changed, 9 insertions(+) > >diff --git a/net/ipv4/route.c b/net/ipv4/route.c >index 85f184e..7e766b5 100644 >--- a/net/ipv4/route.c >+++ b/net/ipv4/route.c >@@ -524,10 +524,19 @@ static void build_skb_flow_key(struct flowi4 *fl4, const struct sk_buff *skb, > { > const struct iphdr *iph = ip_hdr(skb); > int oif = skb->dev->ifindex; >+ struct net_device *master; > u8 tos = RT_TOS(iph->tos); > u8 prot = iph->protocol; > u32 mark = skb->mark; > >+ if (netif_is_bond_slave(skb->dev)) { >+ rcu_read_lock(); >+ master = netdev_master_upper_dev_get_rcu(skb->dev); >+ if (master) >+ oif = master->ifindex; >+ rcu_read_unlock(); >+ } This is certainly not correct as it should not be bond-specific but rather generic. Note that you may have bond over bond or bridge over bond or other scenarios, which this patch ignores.