[PATCH net v3 2/2] selftests/net/openvswitch: check that a failed set keeps the features

@@ -2,10 +2,13 @@ CONFIG_GENEVE=m
 CONFIG_INET_DIAG=y
 CONFIG_IP_SCTP=y
 CONFIG_IPV6=y
+CONFIG_NET_CLS_ACT=y
 CONFIG_NETFILTER=y
 CONFIG_NETFILTER_ADVANCED=y
 CONFIG_NET_IPGRE=m
 CONFIG_NET_IPGRE_DEMUX=m
+CONFIG_NET_SCHED=y
+CONFIG_NET_TC_SKB_EXT=y
 CONFIG_NF_CONNTRACK=m
 CONFIG_NF_CONNTRACK_OVS=y
 CONFIG_NF_CT_PROTO_SCTP=y

@@ -24,6 +24,8 @@ tests="
 	nat_connect_v4				ip4-nat-xon: Basic ipv4 tcp connection via NAT
 	nat_related_v4				ip4-nat-related: ICMP related matches work with SNAT
 	netlink_checks				ovsnl: validate netlink attrs and settings
+	dp_features				ovsdp: rejected set keeps bits
+	dp_features_recirc			ovsdp: recirc survives rejection
 	upcall_interfaces			ovs: test the upcall interfaces
 	tunnel_metadata				ovs: test extraction of tunnel metadata
 	drop_reason				drop: test drop reasons are emitted

@@ -1409,6 +1411,130 @@ test_netlink_checks () {
 	return 0
 }
 
+ovs_dp_features_set() {
+	python3 $ovs_base/ovs-dpctl.py set-dp "$@"
+}
+
+ovs_dp_features_check() {
+	python3 $ovs_base/ovs-dpctl.py show "$1" |
+		grep -q "features: 0x$2\$"
+}
+
+# The number of an errno outside the base list differs by architecture.
+# EINVAL is in the base list and is 22 everywhere.
+ovs_errno() {
+	python3 -c "import errno; print(errno.$1)"
+}
+
+# dp_features test
+# - a set with the dispatch bit and pids is accepted and reported back
+# - a set with an empty per-cpu-pids is rejected with EINVAL and leaves
+#   the features as they were
+# - an outdated new request drops the features, and sets work afterwards
+test_dp_features() {
+	local t="test_dp_features"
+	local dp="dpfeat0"
+
+	sbx_add "$t" || return $?
+	ovs_add_dp "$t" "$dp" || return 1
+
+	info "clear the datapath features"
+	ovs_sbx "$t" ovs_dp_features_set "$dp" --features 0 || return 1
+	ovs_sbx "$t" ovs_dp_features_check "$dp" 0 \
+	    || { info "features were not cleared"; return 1; }
+
+	# 8 is OVS_DP_F_DISPATCH_UPCALL_PER_CPU, the bit that makes the
+	# kernel read per-cpu-pids.
+	info "a set with the dispatch bit and pids is accepted"
+	ovs_sbx "$t" ovs_dp_features_set "$dp" --features 8 \
+	    --per-cpu-pids 1,2 || return 1
+	ovs_sbx "$t" ovs_dp_features_check "$dp" 8 \
+	    || { info "the accepted set was not applied"; return 1; }
+
+	ovs_sbx "$t" ovs_dp_features_set "$dp" --features 0 || return 1
+
+	# ovs-dpctl sends the empty list as an attribute with no payload,
+	# which is what the kernel rejects.
+	info "a set with an empty per-cpu-pids is rejected"
+	ovs_sbx "$t" ovs_dp_features_set "$dp" --features 8 \
+	    --per-cpu-pids "" &> /dev/null
+	[ $? -eq 22 ] \
+	    || { info "the empty per-cpu-pids set did not fail with EINVAL"; \
+		 return 1; }
+
+	info "the rejected set keeps the features it had"
+	ovs_sbx "$t" ovs_dp_features_check "$dp" 0 \
+	    || { info "the rejected set was recorded"; return 1; }
+
+	# An outdated client that asks for an existing datapath again makes
+	# the kernel drop its features. The datapath keeps working.
+	info "an outdated new request drops the features"
+	ovs_sbx "$t" ovs_dp_features_set "$dp" --features 8 || return 1
+	ovs_sbx "$t" python3 $ovs_base/ovs-dpctl.py add-dp "$dp" -V 1:0 \
+	    &> /dev/null
+	ovs_sbx "$t" ovs_dp_features_check "$dp" 0 \
+	    || { info "the outdated new request did not drop the features"; \
+		 return 1; }
+	ovs_sbx "$t" ovs_dp_features_set "$dp" --features 8 \
+	    || { info "the datapath stopped accepting sets"; return 1; }
+	ovs_sbx "$t" ovs_dp_features_check "$dp" 8 \
+	    || { info "the reset datapath took no features"; return 1; }
+
+	return 0
+}
+
+# dp_features_recirc test
+# - a datapath that holds the recirc bit keeps it across a rejected set
+# - an outdated new request drops the features
+# - the bit needs CONFIG_NET_TC_SKB_EXT, so the test skips without it
+test_dp_features_recirc() {
+	local t="test_dp_features_recirc"
+	local dp="dpfeat1"
+
+	sbx_add "$t" || return $?
+	ovs_add_dp "$t" "$dp" || return 1
+
+	ovs_sbx "$t" ovs_dp_features_set "$dp" --features 0 || return 1
+
+	# 4 is OVS_DP_F_TC_RECIRC_SHARING. The kernel takes the bit only when
+	# the tc skb extension is compiled in.
+	ovs_sbx "$t" ovs_dp_features_set "$dp" --features 4 &> /dev/null
+	rc=$?
+	if [ $rc -ne 0 ]; then
+		eopnotsupp=$(ovs_errno EOPNOTSUPP)
+		if [ -n "$eopnotsupp" ] && [ $rc -eq "$eopnotsupp" ]; then
+			# Say it on stdout: a skip that only reaches debug.log
+			# leaves CI with a pass and no sign of the missing
+			# coverage.
+			printf "# tc skb extension is not compiled in," \
+			       "skipping recirc\n"
+			ovs_exit_sig
+			return $ksft_skip
+		fi
+		info "the recirc set failed with $rc"
+		return 1
+	fi
+	ovs_sbx "$t" ovs_dp_features_check "$dp" 4 \
+	    || { info "the accepted recirc set was not applied"; return 1; }
+
+	info "the rejected set keeps the recirc bit"
+	ovs_sbx "$t" ovs_dp_features_set "$dp" --features 8 \
+	    --per-cpu-pids "" &> /dev/null
+	[ $? -eq 22 ] \
+	    || { info "the rejected set did not fail with EINVAL"; return 1; }
+	ovs_sbx "$t" ovs_dp_features_check "$dp" 4 \
+	    || { info "the rejected set dropped the recirc bit"; return 1; }
+
+	info "an outdated new request drops the features"
+	ovs_sbx "$t" python3 $ovs_base/ovs-dpctl.py add-dp "$dp" -V 1:4 \
+	    &> /dev/null
+	ovs_sbx "$t" ovs_dp_features_check "$dp" 0 \
+	    || { info "the outdated new request did not drop the features"; \
+		 return 1; }
+
+	return 0
+}
+
 test_upcall_interfaces() {
 	sbx_add "test_upcall_interfaces" || return 1
 

@@ -2301,6 +2301,24 @@ class OvsDatapath(GenericNetlinkSocket):
 
         return reply
 
+    def set(self, dpname, ifindex=0, features=None, per_cpu_pids=None):
+        msg = OvsDatapath.dp_cmd_msg()
+        msg["cmd"] = OVS_DP_CMD_SET
+        msg["version"] = OVS_DATAPATH_VERSION
+        msg["reserved"] = 0
+        msg["dpifindex"] = ifindex
+        msg["attrs"].append(["OVS_DP_ATTR_NAME", dpname])
+        if features is not None:
+            msg["attrs"].append(["OVS_DP_ATTR_USER_FEATURES", features])
+        if per_cpu_pids is not None:
+            msg["attrs"].append(["OVS_DP_ATTR_PER_CPU_PIDS", per_cpu_pids])
+
+        reply = self.nlm_request(
+            msg, msg_type=self.prid, msg_flags=NLM_F_REQUEST | NLM_F_ACK
+        )
+
+        return reply[0]
+
     def create(
         self, dpname, shouldUpcall=False, versionStr=None, p=OvsPacket()
     ):

@@ -2961,6 +2979,23 @@ def main(argv):
     deldpcmd = subparsers.add_parser("del-dp")
     deldpcmd.add_argument("deldp", help="Datapath Name")
 
+    setdpcmd = subparsers.add_parser("set-dp")
+    setdpcmd.add_argument("setdp", help="Datapath Name")
+    setdpcmd.add_argument(
+        "-f",
+        "--features",
+        type=lambda x: int(x, 0),
+        default=None,
+        help="Datapath user features, defaults to the current value",
+    )
+    setdpcmd.add_argument(
+        "-p",
+        "--per-cpu-pids",
+        type=str,
+        default=None,
+        help="Comma separated upcall pids, an empty string sends none",
+    )
+
     addifcmd = subparsers.add_parser("add-if")
     addifcmd.add_argument("dpname", help="Datapath Name")
     addifcmd.add_argument("addif", help="Interface name for adding")

@@ -3057,6 +3092,31 @@ def main(argv):
             ovspk.upcall_handler(ovsflow)
     elif hasattr(args, "deldp"):
         ovsdp.destroy(args.deldp)
+    elif hasattr(args, "setdp"):
+        rep = ovsdp.info(args.setdp, 0)
+        if rep is None:
+            print(f"DP '{args.setdp}' not found.")
+            return 1
+        pids = None
+        if args.per_cpu_pids is not None:
+            try:
+                pids = [int(x) for x in args.per_cpu_pids.split(",")
+                        if x != ""]
+            except ValueError:
+                print(f"invalid per-cpu-pids: {args.per_cpu_pids}")
+                return 1
+        features = args.features
+        if features is None:
+            features = rep.get_attr("OVS_DP_ATTR_USER_FEATURES")
+            if features is None:
+                print(f"DP '{args.setdp}' does not report its features")
+                return 1
+        try:
+            ovsdp.set(args.setdp, rep["dpifindex"], features, pids)
+        except NetlinkError as ne:
+            print(f"set failed: {ne.args[1]}")
+            return ne.code
+        print(f"DP '{args.setdp}' updated")
     elif hasattr(args, "addif"):
         rep = ovsdp.info(args.dpname, 0)
         if rep is None: