selftests: mptcp: enable checksum in mptcp_connect.sh

This patch added a new argument "-C" for the mptcp_connect.sh script to
set the sysctl checksum_enabled to 1 in ns1, ns2, ns3 and ns4 to enable
the data checksum.
Acked-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Geliang Tang <geliangtang@gmail.com>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

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

@@ -3,7 +3,7 @@
 
 time_start=$(date +%s)
 
-optstring="S:R:d:e:l:r:h4cm:f:t"
+optstring="S:R:d:e:l:r:h4cm:f:tC"
 ret=0
 sin=""
 sout=""
@@ -22,6 +22,7 @@ sndbuf=0
 rcvbuf=0
 options_log=true
 do_tcp=0
+checksum=false
 filesize=0
 
 if [ $tc_loss -eq 100 ];then
@@ -47,6 +48,7 @@ usage() {
 	echo -e "\t-R: set rcvbuf value (default: use kernel default)"
 	echo -e "\t-m: test mode (poll, sendfile; default: poll)"
 	echo -e "\t-t: also run tests with TCP (use twice to non-fallback tcp)"
+	echo -e "\t-C: enable the MPTCP data checksum"
 }
 
 while getopts "$optstring" option;do
@@ -104,6 +106,9 @@ while getopts "$optstring" option;do
 	"t")
 		do_tcp=$((do_tcp+1))
 		;;
+	"C")
+		checksum=true
+		;;
 	"?")
 		usage $0
 		exit 1
@@ -200,6 +205,12 @@ ip -net "$ns4" route add default via dead:beef:3::2
 # use TCP syn cookies, even if no flooding was detected.
 ip netns exec "$ns2" sysctl -q net.ipv4.tcp_syncookies=2
 
+if $checksum; then
+	for i in "$ns1" "$ns2" "$ns3" "$ns4";do
+		ip netns exec $i sysctl -q net.mptcp.checksum_enabled=1
+	done
+fi
+
 set_ethtool_flags() {
 	local ns="$1"
 	local dev="$2"