[PATCH] Fix sending duplicate LACP frames at the start of establishing a logical channel.

[Samudrala, Sridhar]

This issue can be seen with the following test script. It creates 2 net
namespaces connected via a veth pair and then creates team over the veth
interface in each namespace. tcpdump is run in background to collect the
lacp frames. The trace shows 11 lacp frames exchanged with multiple duplicates
within the first second.

================================================================================
#!/bin/bash

set -x
set -e

# create 2 network namespaces: ns1 & ns2
ip netns add ns1
ip netns add ns2

# create veth pair (veth-ns1 and veth-ns2)
ip link add veth-ns1 type veth peer name veth-ns2

# move veth-ns1 to ns1
ip link set veth-ns1 netns ns1

# move veth-ns2 to ns2
ip link set veth-ns2 netns ns2

# create and configure team-veth-ns1 in ns1
ip netns exec ns1 ./teamd -d -c '{"device": "team-veth-ns1",
"hwaddr": "00:55:BB:BB:BB:01", "runner": {"name":
"lacp", "active": true, "fast_rate": true},
"ports": {"veth-ns1": {}}}'

# capture lacp frames in ns1
ip netns exec ns1 tcpdump -w lacp.pcap -c 20 -n -i veth-ns1 -e ether proto 0x8809 &

# create and configure team-veth-ns2 ns2
ip netns exec ns2 ./teamd -d -c '{"device": "team-veth-ns2",
"hwaddr": "00:55:BB:BB:BB:02", "runner": {"name":
"lacp", "active": true, "fast_rate": true},
"ports": {"veth-ns2": {}}}'

sleep 10 
================================================================================

With this patch only 3 lacp frames are exchanged in the first second with no
duplicates.

Signed-off-by: Sridhar Samudrala <sridhar.samudrala(a)intel.com&gt;
---
 teamd/teamd_runner_lacp.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/teamd/teamd_runner_lacp.c b/teamd/teamd_runner_lacp.c
index b35e427..b34f057 100644
--- a/teamd/teamd_runner_lacp.c
+++ b/teamd/teamd_runner_lacp.c
@@ -903,6 +903,10 @@ static int lacp_port_actor_update(struct lacp_port *lacp_port)
 	teamd_log_dbg("%s: lacp info state: 0x%02X.",
lacp_port->tdport->ifname,
 						      state);
 	lacp_port->actor.state = state;
+
+	if (lacp_port->periodic_on)
+		return 0;
+
 	return lacpdu_send(lacp_port);
 }
 
@@ -1056,7 +1060,8 @@ static int lacpdu_recv(struct lacp_port *lacp_port)
 		return err;
 
 	/* Check if the other side has correct info about us */
-	if (memcmp(&lacpdu.partner, &lacp_port->actor,
+	if (!lacp_port->periodic_on &&
+	    memcmp(&lacpdu.partner, &lacp_port->actor,
 		   sizeof(struct lacpdu_info))) {
 		err = lacpdu_send(lacp_port);
 		if (err)
-- 
2.1.0

[Jiri Pirko]

Fri, Jul 24, 2015 at 12:49:33AM CEST, sridhar.samudrala(a)intel.com wrote:
> This issue can be seen with the following test script. It creates 2
> net
> namespaces connected via a veth pair and then creates team over the veth
> interface in each namespace. tcpdump is run in background to collect the
> lacp frames. The trace shows 11 lacp frames exchanged with multiple duplicates
> within the first second.
>
> ================================================================================
> #!/bin/bash
>
> set -x
> set -e
>
> # create 2 network namespaces: ns1 & ns2
> ip netns add ns1
> ip netns add ns2
>
> # create veth pair (veth-ns1 and veth-ns2)
> ip link add veth-ns1 type veth peer name veth-ns2
>
> # move veth-ns1 to ns1
> ip link set veth-ns1 netns ns1
>
> # move veth-ns2 to ns2
> ip link set veth-ns2 netns ns2
>
> # create and configure team-veth-ns1 in ns1
> ip netns exec ns1 ./teamd -d -c '{"device": "team-veth-ns1",
> "hwaddr": "00:55:BB:BB:BB:01", "runner": {"name":
> "lacp", "active": true, "fast_rate": true},
> "ports": {"veth-ns1": {}}}'
>
> # capture lacp frames in ns1
> ip netns exec ns1 tcpdump -w lacp.pcap -c 20 -n -i veth-ns1 -e ether proto 0x8809 &
>
> # create and configure team-veth-ns2 ns2
> ip netns exec ns2 ./teamd -d -c '{"device": "team-veth-ns2",
> "hwaddr": "00:55:BB:BB:BB:02", "runner": {"name":
> "lacp", "active": true, "fast_rate": true},
> "ports": {"veth-ns2": {}}}'
>
> sleep 10 
> ================================================================================
>
> With this patch only 3 lacp frames are exchanged in the first second with no
> duplicates.
>
> Signed-off-by: Sridhar Samudrala <sridhar.samudrala(a)intel.com&gt; 
applied, thanks!