From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jay Vosburgh Subject: Re: [PATCH] net: take care of bonding in build_skb_flow_key (v2) Date: Tue, 12 Jan 2016 12:22:48 -0800 Message-ID: <12940.1452630168@famine> References: <1452070997-10395-1-git-send-email-wen.gang.wang@oracle.com> Cc: netdev@vger.kernel.org To: Wengang Wang Return-path: Received: from youngberry.canonical.com ([91.189.89.112]:49419 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753138AbcALUWv (ORCPT ); Tue, 12 Jan 2016 15:22:51 -0500 In-reply-to: <1452070997-10395-1-git-send-email-wen.gang.wang@oracle.com> Sender: netdev-owner@vger.kernel.org List-ID: Wengang Wang 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. Does the team driver have the equivalent issue? >Signed-off-by: Wengang Wang >--- > net/ipv4/route.c | 10 +++++++++- > 1 file changed, 9 insertions(+), 1 deletion(-) > >diff --git a/net/ipv4/route.c b/net/ipv4/route.c >index 85f184e..fffc7e6 100644 >--- a/net/ipv4/route.c >+++ b/net/ipv4/route.c >@@ -523,10 +523,18 @@ static void build_skb_flow_key(struct flowi4 *fl4, const struct sk_buff *skb, > const struct sock *sk) > { > const struct iphdr *iph = ip_hdr(skb); >- int oif = skb->dev->ifindex; > u8 tos = RT_TOS(iph->tos); >+ struct net_device *master; > u8 prot = iph->protocol; > u32 mark = skb->mark; >+ int oif; >+ >+ if (skb->dev->flags & IFF_SLAVE) { >+ master = netdev_master_upper_dev_get(skb->dev); >+ oif = master->ifindex; >+ } else { >+ oif = skb->dev->ifindex; >+ } netdev_master_upper_dev_get() requires RTNL to be held; I don't see that all callers to build_skb_flow_key will do so. I also believe the above would dereference a NULL pointer if an eql device is configured, as it uses IFF_SLAVE but doesn't use the upper/lower device infrastructure, thus, netdev_master_upper_dev_get() would likely return NULL for eql. -J --- -Jay Vosburgh, jay.vosburgh@canonical.com