Bug 1808125

ovn2.12.x86_64 0:2.12.0-32.el7fdn

openvswitch2.12.x86_64 0:2.12.0-21.el7fdn

Created attachment 1666372 [details]
Full sbdb logs (leader + followers)

Created attachment 1666376 [details]
working vs not-working ovn-controller logs (different nodes in the same run)

From the sbdb_leader.log we see that the ovn-controller where the issue is seen ("server13" in the logs) sends an incorrect "monitor_cond_since" request:

2020-02-27T21:03:38Z|02948|jsonrpc|DBG|ssl:10.0.0.3:38012: received request, method="monitor_cond_since", params=[
    "OVN_Southbound",
    ["monid","OVN_Southbound"],
    [...]
    "Port_Binding":
        [
            {"where":
                [
                    ["type","==","patch"],
                    ["type","==","chassisredirect"],
                    ["type","==","external"]
                ],
            "columns":
                [
                    "chassis",
                    "datapath",
                    "encap",
                    "gateway_chassis",
                    "ha_chassis_group",
                    "logical_port",
                    "mac",
                    "nat_addresses",
                    "options",
                    "parent_port",
                    "tag",
                    "tunnel_key",
                    "type",
                    "virtual_parent"
                ]
            }
        ],
        [...]
After this point the ovn-controller facing the issue ("server13") doesn't update the monitor condition, i.e., it doesn't send any other monitor_cond_since requests to OVSDB SB server.

From the sbdb_follower2.log where the ovn-controller that doesn't hit the issue is connected ("server9" in the logs), we see the correct "monitor_cond_since" request, specifically no "where" clause for Port_Binding:

2020-02-27T21:03:38Z|01610|jsonrpc|DBG|ssl:10.0.0.4:42758: received request, method="monitor_cond_since", params=[
    "OVN_Southbound",
    ["monid","OVN_Southbound"],
    [...]
    "Port_Binding":
        [
            {"columns":
                [
                    "chassis",
                    "datapath",
                    "encap",
                    "gateway_chassis",
                    "ha_chassis_group",
                    "logical_port",
                    "mac",
                    "nat_addresses",
                    "options",
                    "parent_port",
                    "tag",
                    "tunnel_key",
                    "type",
                    "virtual_parent"
                ]
            }
        ],

This indicates that ovn-controller sometimes fails to properly disable conditional monitoring when ovn-monitor-all=true.

Steps to replicate the issue using the attached OVS, OVN SB, OVN NB database files:

1. start OVS with the ovsdb.db database.
2. start OVN northd and NB/SB databases. E.g.:
/usr/share/ovn/scripts/ovn-ctl start_northd --db-nb-cluster-local-addr=127.0.0.1 --db-sb-cluster-local-addr=127.0.0.1
3. Attach the following gdb script to ovsdb-server SB:

$ cat gdb-commands
b ovsdb_jsonrpc_parse_monitor_request if (strcmp(table->schema->name, "Database"))
commands
shell ovs-vsctl set open . external-ids:ovn-monitor-all=true
print sleep(1)
dis
c
end
c

$ ovs-vsctl set open . external-ids:ovn-monitor-all=false
$ ovn-sbctl destroy chassis .
$ ovn-sbctl destroy port_binding k8s-ci-op-7pxtd-m-0.c.openshift-gce-devel-ci.internal
$ spid=$(ps aux | grep -v grep | grep ovsdb-server-sb | tr -s ' ' | cut -d ' ' -f 2)
$ gdb -p $spid -x gdb-commands

This clears ovn-monitor-all from the OVS database and also the relevant chassis and port bindings in the SB DB. Then it attaches to the ovsdb-server for SB and sets a breakpoint for when it would receive the monitor_cond_since command from ovn-controller for the OVN_Southbound database. At this point, before replying to ovn-controller the breakpoint script sets ovn-monitor-all=true (simulating what ovn-k8s would do), sleeps for 1 sec making sure ovn-controller received the update from OVS, and continues.

4. Start ovn-controller:
/usr/share/ovn/scripts/ovn-ctl start_controller

5. Check that the port binding wasn't claimed by ovn-controller:
$ ovn-sbctl --columns chassis list port_binding k8s-ci-op-7pxtd-m-0.c.openshift-gce-devel-ci.internal
chassis             : []

Root cause:
ovn-controller shouldn't call update_sb_monitors if the SB IDL is in state IDL_S_DATA_MONITOR_COND_SINCE_REQUESTED because when ovsdb-server replies the IDL code will:
- call ovsdb_idl_db_parse_monitor_reply() [1]
- call ovsdb_idl_db_clear() [2]
- which sets table->cond_changed = false; for every table monitored by the IDL. [3]

[1] https://github.com/openvswitch/ovs/blob/master/lib/ovsdb-idl.c#L767
[2] https://github.com/openvswitch/ovs/blob/master/lib/ovsdb-idl.c#L2153
[3] https://github.com/openvswitch/ovs/blob/master/lib/ovsdb-idl.c#L613

Fix sent upstream for review: https://patchwork.ozlabs.org/patch/1246910/

Fix merged upstream: https://github.com/openvswitch/ovs/commit/2b7e536fa5e20be10e620b959e05557f88862d2c