[PATCH net 3/4] selftests: openvswitch: Skip drop testing on older kernels

[Aaron Conole]

Kernels that don't have support for openvswitch drop reasons also
won't have the drop counter reasons, so we should skip the test
completely.  It previously wasn't possible to build a test case
for this without polluting the datapath, so we introduce a mechanism
to clear all the flows from a datapath allowing us to test for
explicit drop actions, and then clear the flows to build the
original test case.

Fixes: 4242029164d6 ("selftests: openvswitch: add explicit drop testcase")
Signed-off-by: Aaron Conole <aconole@xxxxxxxxxx>
---
 .../selftests/net/openvswitch/openvswitch.sh  | 17 ++++++++++
 .../selftests/net/openvswitch/ovs-dpctl.py    | 34 +++++++++++++++++++
 2 files changed, 51 insertions(+)

diff --git a/tools/testing/selftests/net/openvswitch/openvswitch.sh b/tools/testing/selftests/net/openvswitch/openvswitch.sh
index 2a0112be7ead5..ca7090e71bff2 100755
--- a/tools/testing/selftests/net/openvswitch/openvswitch.sh
+++ b/tools/testing/selftests/net/openvswitch/openvswitch.sh
@@ -144,6 +144,12 @@ ovs_add_flow () {
 	return 0
 }
 
+ovs_del_flows () {
+	info "Deleting all flows from DP: sbx:$1 br:$2"
+	ovs_sbx "$1" python3 $ovs_base/ovs-dpctl.py del-flows "$2"
+        return 0
+}
+
 ovs_drop_record_and_run () {
 	local sbx=$1
 	shift
@@ -200,6 +206,17 @@ test_drop_reason() {
 	ip netns exec server ip addr add 172.31.110.20/24 dev s1
 	ip netns exec server ip link set s1 up
 
+	# Check if drop reasons can be sent
+	ovs_add_flow "test_drop_reason" dropreason \
+		'in_port(1),eth(),eth_type(0x0806),arp()' 'drop(10)' 2>/dev/null
+	if [ $? == 1 ]; then
+		info "no support for drop reasons - skipping"
+		ovs_exit_sig
+		return $ksft_skip
+	fi
+
+	ovs_del_flows "test_drop_reason" dropreason
+
 	# Allow ARP
 	ovs_add_flow "test_drop_reason" dropreason \
 		'in_port(1),eth(),eth_type(0x0806),arp()' '2' || return 1
diff --git a/tools/testing/selftests/net/openvswitch/ovs-dpctl.py b/tools/testing/selftests/net/openvswitch/ovs-dpctl.py
index 9686ca30d516d..153042c1e8c13 100644
--- a/tools/testing/selftests/net/openvswitch/ovs-dpctl.py
+++ b/tools/testing/selftests/net/openvswitch/ovs-dpctl.py
@@ -1906,6 +1906,32 @@ class OvsFlow(GenericNetlinkSocket):
             raise ne
         return reply
 
+    def del_flows(self, dpifindex):
+        """
+        Send a del message to the kernel that will drop all flows.
+
+        dpifindex should be a valid datapath obtained by calling
+        into the OvsDatapath lookup
+        """
+
+        flowmsg = OvsFlow.ovs_flow_msg()
+        flowmsg["cmd"] = OVS_FLOW_CMD_DEL
+        flowmsg["version"] = OVS_DATAPATH_VERSION
+        flowmsg["reserved"] = 0
+        flowmsg["dpifindex"] = dpifindex
+
+        try:
+            reply = self.nlm_request(
+                flowmsg,
+                msg_type=self.prid,
+                msg_flags=NLM_F_REQUEST | NLM_F_ACK,
+            )
+            reply = reply[0]
+        except NetlinkError as ne:
+            print(flowmsg)
+            raise ne
+        return reply
+
     def dump(self, dpifindex, flowspec=None):
         """
         Returns a list of messages containing flows.
@@ -2068,6 +2094,9 @@ def main(argv):
     addflcmd.add_argument("flow", help="Flow specification")
     addflcmd.add_argument("acts", help="Flow actions")
 
+    delfscmd = subparsers.add_parser("del-flows")
+    delfscmd.add_argument("flsbr", help="Datapath name")
+
     args = parser.parse_args()
 
     if args.verbose > 0:
@@ -2151,6 +2180,11 @@ def main(argv):
         flow = OvsFlow.ovs_flow_msg()
         flow.parse(args.flow, args.acts, rep["dpifindex"])
         ovsflow.add_flow(rep["dpifindex"], flow)
+    elif hasattr(args, "flsbr"):
+        rep = ovsdp.info(args.flsbr, 0)
+        if rep is None:
+            print("DP '%s' not found." % args.flsbr)
+        ovsflow.del_flows(rep["dpifindex"])
 
     return 0
 
-- 
2.40.1