| Message ID | 1399967708-7283-1-git-send-email-jmaxwell@redhat.com |
|---|---|
| State | Changes Requested, archived |
| Delegated to: | David Miller |
| Headers | show |
Tue, May 13, 2014 at 09:55:08AM CEST, jmaxwell37@gmail.com wrote: >From: Jon Maxwell <jmaxwell37@gmail.com> > >There has been a number incidents recently where customers running KVM have >reported that VM hosts on different Hypervisors are unreachable. Based on >pcap traces we found that the bridge was broadcasting the ARP request out >onto the network. However some NICs have an inbuilt switch which on occasions >were broadcasting the VMs ARP request back through the physical NIC on the >Hypervisor. This resulted in the bridge changing ports and incorrectly learning >that the VMs mac address was external. As a result the ARP reply was directed >back onto the external network and VM never updated it's ARP cache. This patch >will notify the bridge command to identify such port toggling. > >Signed-off-by: Jon Maxwell <jmaxwell37@gmail.com> >--- > net/bridge/br_fdb.c | 2 ++ > 1 file changed, 2 insertions(+) > >diff --git a/net/bridge/br_fdb.c b/net/bridge/br_fdb.c >index 9203d5a..37742e2 100644 >--- a/net/bridge/br_fdb.c >+++ b/net/bridge/br_fdb.c >@@ -507,6 +507,8 @@ void br_fdb_update(struct net_bridge *br, struct net_bridge_port *source, > source->dev->name); > } else { > /* fastpath: update of existing entry */ >+ if (source->port_no != fdb->dst->port_no) >+ fdb_notify(br, fdb, RTM_NEWNEIGH); > fdb->dst = source; > fdb->updated = jiffies; > if (unlikely(added_by_user)) >-- >1.8.3.1 Reviewed-by: Jiri Pirko <jiri@resnulli.us> -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Tue, 13 May 2014 17:16:11 +0200 Jiri Pirko <jiri@resnulli.us> wrote: > Tue, May 13, 2014 at 09:55:08AM CEST, jmaxwell37@gmail.com wrote: > >From: Jon Maxwell <jmaxwell37@gmail.com> > > > >There has been a number incidents recently where customers running KVM have > >reported that VM hosts on different Hypervisors are unreachable. Based on > >pcap traces we found that the bridge was broadcasting the ARP request out > >onto the network. However some NICs have an inbuilt switch which on occasions > >were broadcasting the VMs ARP request back through the physical NIC on the > >Hypervisor. This resulted in the bridge changing ports and incorrectly learning > >that the VMs mac address was external. As a result the ARP reply was directed > >back onto the external network and VM never updated it's ARP cache. This patch > >will notify the bridge command to identify such port toggling. > > > >Signed-off-by: Jon Maxwell <jmaxwell37@gmail.com> > >--- > > net/bridge/br_fdb.c | 2 ++ > > 1 file changed, 2 insertions(+) > > > >diff --git a/net/bridge/br_fdb.c b/net/bridge/br_fdb.c > >index 9203d5a..37742e2 100644 > >--- a/net/bridge/br_fdb.c > >+++ b/net/bridge/br_fdb.c > >@@ -507,6 +507,8 @@ void br_fdb_update(struct net_bridge *br, struct net_bridge_port *source, > > source->dev->name); > > } else { > > /* fastpath: update of existing entry */ > >+ if (source->port_no != fdb->dst->port_no) > >+ fdb_notify(br, fdb, RTM_NEWNEIGH); > > fdb->dst = source; > > fdb->updated = jiffies; > > if (unlikely(added_by_user)) > >-- > >1.8.3.1 > > > Reviewed-by: Jiri Pirko <jiri@resnulli.us> I like the patch, but please add unlikely() to this conditional. This is in the fast path code for bridge learning. -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
(2014/05/13 16:55), Jon Maxwell wrote: > From: Jon Maxwell <jmaxwell37@gmail.com> > > There has been a number incidents recently where customers running KVM have > reported that VM hosts on different Hypervisors are unreachable. Based on > pcap traces we found that the bridge was broadcasting the ARP request out > onto the network. However some NICs have an inbuilt switch which on occasions > were broadcasting the VMs ARP request back through the physical NIC on the > Hypervisor. This resulted in the bridge changing ports and incorrectly learning > that the VMs mac address was external. As a result the ARP reply was directed > back onto the external network and VM never updated it's ARP cache. This patch > will notify the bridge command to identify such port toggling. > > Signed-off-by: Jon Maxwell <jmaxwell37@gmail.com> > --- > net/bridge/br_fdb.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/net/bridge/br_fdb.c b/net/bridge/br_fdb.c > index 9203d5a..37742e2 100644 > --- a/net/bridge/br_fdb.c > +++ b/net/bridge/br_fdb.c > @@ -507,6 +507,8 @@ void br_fdb_update(struct net_bridge *br, struct net_bridge_port *source, > source->dev->name); > } else { > /* fastpath: update of existing entry */ > + if (source->port_no != fdb->dst->port_no) It seems that we don't need to fetch port_no and it is enough to compare source and fdb->dst. > + fdb_notify(br, fdb, RTM_NEWNEIGH); > fdb->dst = source; > fdb->updated = jiffies; > if (unlikely(added_by_user)) > This notifies fdb entry before updating existing entry. Is this on purpose? I think we should notify the updated fdb entry. Similar code fdb_add_entry() does after updating it. Also, isn't it better to move update of dst into "if" block? if (source != fdb->dst) { fdb->dst = source; modified = true; } ... if (modified) ... Thanks, Toshiaki Makita -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
----- Original Message ----- > From: "Toshiaki Makita" <makita.toshiaki@lab.ntt.co.jp> > To: "Jon Maxwell" <jmaxwell37@gmail.com>, stephen@networkplumber.org > Cc: davem@davemloft.net, vyasevic@redhat.com, bridge@lists.linux-foundation.org, netdev@vger.kernel.org, > linux-kernel@vger.kernel.org, jpirko@redhat.com, jmaxwell@redhat.com > Sent: Wednesday, May 14, 2014 10:34:38 AM > Subject: Re: [PATCH net] bridge: notify user space of fdb port change > > (2014/05/13 16:55), Jon Maxwell wrote: > > From: Jon Maxwell <jmaxwell37@gmail.com> > > > > There has been a number incidents recently where customers running KVM have > > reported that VM hosts on different Hypervisors are unreachable. Based on > > pcap traces we found that the bridge was broadcasting the ARP request out > > onto the network. However some NICs have an inbuilt switch which on > > occasions > > were broadcasting the VMs ARP request back through the physical NIC on the > > Hypervisor. This resulted in the bridge changing ports and incorrectly > > learning > > that the VMs mac address was external. As a result the ARP reply was > > directed > > back onto the external network and VM never updated it's ARP cache. This > > patch > > will notify the bridge command to identify such port toggling. > > > > Signed-off-by: Jon Maxwell <jmaxwell37@gmail.com> > > --- > > net/bridge/br_fdb.c | 2 ++ > > 1 file changed, 2 insertions(+) > > > > diff --git a/net/bridge/br_fdb.c b/net/bridge/br_fdb.c > > index 9203d5a..37742e2 100644 > > --- a/net/bridge/br_fdb.c > > +++ b/net/bridge/br_fdb.c > > @@ -507,6 +507,8 @@ void br_fdb_update(struct net_bridge *br, struct > > net_bridge_port *source, > > source->dev->name); > > } else { > > /* fastpath: update of existing entry */ > > + if (source->port_no != fdb->dst->port_no) > > It seems that we don't need to fetch port_no and it is enough to compare > source and fdb->dst. It may save a few instructions but I have not tested it. > > > + fdb_notify(br, fdb, RTM_NEWNEIGH); > > fdb->dst = source; > > fdb->updated = jiffies; > > if (unlikely(added_by_user)) > > > > This notifies fdb entry before updating existing entry. Is this on purpose? > I think we should notify the updated fdb entry. > Similar code fdb_add_entry() does after updating it. It was not on purpose but for this particular case there will be burst of notifies so it probably does not matter. However I agree it should be after the update. I will do that along with adding the unlikely() conditional and resubmit. > > Also, isn't it better to move update of dst into "if" block? I would prefer to leave this portion as alone and only use the if statement for the notify. > > if (source != fdb->dst) { > fdb->dst = source; > modified = true; > } > ... > if (modified) ... > > Thanks, > Toshiaki Makita > -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/net/bridge/br_fdb.c b/net/bridge/br_fdb.c index 9203d5a..37742e2 100644 --- a/net/bridge/br_fdb.c +++ b/net/bridge/br_fdb.c @@ -507,6 +507,8 @@ void br_fdb_update(struct net_bridge *br, struct net_bridge_port *source, source->dev->name); } else { /* fastpath: update of existing entry */ + if (source->port_no != fdb->dst->port_no) + fdb_notify(br, fdb, RTM_NEWNEIGH); fdb->dst = source; fdb->updated = jiffies; if (unlikely(added_by_user))