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Date: Mon, 14 Jun 2010 11:23:19 -0700 From: Randy Dunlap <randy.dunlap@...cle.com> To: Thomas Bächler <thomas@...hlinux.org> Cc: "David S. Miller" <davem@...emloft.net>, John Fastabend <john.r.fastabend@...el.com>, netdev@...r.kernel.org, linux-kernel@...r.kernel.org Subject: Re: [2.6.35-rc3 regression] TCP connections on 'lo' interface randomly stall On Mon, 14 Jun 2010 20:10:27 +0200 Thomas Bächler wrote: > With 2.6.35-rc3, I cannot use TCP over the 'lo' interface any more. This > is reproduced easily by running 'ssh localhost' and executing a few > commands inside the ssh session (if you are able to log in, 'ls -lhFR /' > does a good job) - the connection will stall completely after a very > short time. As far as I can see, all applications are affected. > > It also seems that once a service is "stalled", I cannot open a new > connection to the same TCP port anymore. However, I can open a > connection to a different port until that one is stalled, too. > > Running wireshark, I can see that TCP retransmissions are sent, but > never acknowledged. > > Bisection (starting with 7908a9e as good and v2.6.35-rc3 as bad) leads > to the following commit. Please CC me on replies to this issue. Thanks > for your help. Does this patch fix it for you? http://lkml.org/lkml/2010/6/13/155 > commit 597a264b1a9c7e36d1728f677c66c5c1f7e3b837 > Author: John Fastabend <john.r.fastabend@...el.com> > Date: Thu Jun 3 09:30:11 2010 +0000 > > net: deliver skbs on inactive slaves to exact matches > > Currently, the accelerated receive path for VLAN's will > drop packets if the real device is an inactive slave and > is not one of the special pkts tested for in > skb_bond_should_drop(). This behavior is different then > the non-accelerated path and for pkts over a bonded vlan. > > For example, > > vlanx -> bond0 -> ethx > > will be dropped in the vlan path and not delivered to any > packet handlers at all. However, > > bond0 -> vlanx -> ethx > > and > > bond0 -> ethx > > will be delivered to handlers that match the exact dev, > because the VLAN path checks the real_dev which is not a > slave and netif_recv_skb() doesn't drop frames but only > delivers them to exact matches. > > This patch adds a sk_buff flag which is used for tagging > skbs that would previously been dropped and allows the > skb to continue to skb_netif_recv(). Here we add > logic to check for the deliver_no_wcard flag and if it > is set only deliver to handlers that match exactly. This > makes both paths above consistent and gives pkt handlers > a way to identify skbs that come from inactive slaves. > Without this patch in some configurations skbs will be > delivered to handlers with exact matches and in others > be dropped out right in the vlan path. > > I have tested the following 4 configurations in failover modes > and load balancing modes. > > # bond0 -> ethx > > # vlanx -> bond0 -> ethx > > # bond0 -> vlanx -> ethx > > # bond0 -> ethx > | > vlanx -> -- > > Signed-off-by: John Fastabend <john.r.fastabend@...el.com> > Signed-off-by: David S. Miller <davem@...emloft.net> > --- ~Randy *** Remember to use Documentation/SubmitChecklist when testing your code *** -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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