selftests: mptcp: add tc check for check_tools

tc are used in some test scripts: mptcp_connect.sh, mptcp_join.sh and
simult_flows.sh. It makes sense to check if tc is installed before running
these scripts, just like other tools. So this patch add 'tc' check for
mptcp_lib_check_tools(), and check it in these test scripts.
Signed-off-by: Geliang Tang <tanggeliang@kylinos.cn>
Reviewed-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

tools/testing/selftests/net/mptcp/mptcp_connect.sh

@@ -147,7 +147,7 @@ cleanup()
 
 mptcp_lib_check_mptcp
 mptcp_lib_check_kallsyms
-mptcp_lib_check_tools ip
+mptcp_lib_check_tools ip tc
 
 sin=$(mktemp)
 sout=$(mktemp)

tools/testing/selftests/net/mptcp/mptcp_join.sh

@@ -142,7 +142,7 @@ init() {
 
 	mptcp_lib_check_mptcp
 	mptcp_lib_check_kallsyms
-	mptcp_lib_check_tools ip ss "${iptables}" "${ip6tables}"
+	mptcp_lib_check_tools ip tc ss "${iptables}" "${ip6tables}"
 
 	sin=$(mktemp)
 	sout=$(mktemp)

tools/testing/selftests/net/mptcp/mptcp_lib.sh

@@ -384,6 +384,12 @@ mptcp_lib_check_tools() {
 				exit ${KSFT_SKIP}
 			fi
 			;;
+		"tc")
+			if ! tc -help &> /dev/null; then
+				mptcp_lib_pr_skip "Could not run test without tc tool"
+				exit ${KSFT_SKIP}
+			fi
+			;;
 		"ss")
 			if ! ss -h | grep -q MPTCP; then
 				mptcp_lib_pr_skip "ss tool does not support MPTCP"

tools/testing/selftests/net/mptcp/simult_flows.sh

@@ -45,7 +45,7 @@ cleanup()
 }
 
 mptcp_lib_check_mptcp
-mptcp_lib_check_tools ip
+mptcp_lib_check_tools ip tc
 
 #  "$ns1"              ns2                    ns3
 #     ns1eth1    ns2eth1   ns2eth3      ns3eth1