diff --git a/tools/testing/selftests/net/mptcp/diag.sh b/tools/testing/selftests/net/mptcp/diag.sh
index 18d37d4695c187db8ebefc6af91995c593609239..67bf1e6fa9314b4fa04d94c9bb9dc0b2fae7a6ad 100755
--- a/tools/testing/selftests/net/mptcp/diag.sh
+++ b/tools/testing/selftests/net/mptcp/diag.sh
@@ -8,7 +8,7 @@ rndh=$(printf %x $sec)-$(mktemp -u XXXXXX)
 ns="ns1-$rndh"
 ksft_skip=4
 test_cnt=1
-timeout_poll=100
+timeout_poll=30
 timeout_test=$((timeout_poll * 2 + 1))
 ret=0
 
diff --git a/tools/testing/selftests/net/mptcp/mptcp_join.sh b/tools/testing/selftests/net/mptcp/mptcp_join.sh
index 2db5f6d5773e0c6e74f180c2b24bbfd7ef763e0e..2d47c7d64c303dee03e026f7b9fdc8e3880bcb57 100755
--- a/tools/testing/selftests/net/mptcp/mptcp_join.sh
+++ b/tools/testing/selftests/net/mptcp/mptcp_join.sh
@@ -30,11 +30,11 @@ iptables="iptables"
 ip6tables="ip6tables"
 timeout_poll=30
 timeout_test=$((timeout_poll * 2 + 1))
-capture=0
-checksum=0
+capture=false
+checksum=false
 ip_mptcp=0
 check_invert=0
-validate_checksum=0
+validate_checksum=false
 init=0
 evts_ns1=""
 evts_ns2=""
@@ -101,7 +101,7 @@ init_partial()
 		ip netns exec $netns sysctl -q net.mptcp.pm_type=0 2>/dev/null || true
 		ip netns exec $netns sysctl -q net.ipv4.conf.all.rp_filter=0
 		ip netns exec $netns sysctl -q net.ipv4.conf.default.rp_filter=0
-		if [ $checksum -eq 1 ]; then
+		if $checksum; then
 			ip netns exec $netns sysctl -q net.mptcp.checksum_enabled=1
 		fi
 	done
@@ -388,7 +388,7 @@ reset_with_checksum()
 	ip netns exec $ns1 sysctl -q net.mptcp.checksum_enabled=$ns1_enable
 	ip netns exec $ns2 sysctl -q net.mptcp.checksum_enabled=$ns2_enable
 
-	validate_checksum=1
+	validate_checksum=true
 }
 
 reset_with_allow_join_id0()
@@ -421,7 +421,7 @@ reset_with_allow_join_id0()
 setup_fail_rules()
 {
 	check_invert=1
-	validate_checksum=1
+	validate_checksum=true
 	local i="$1"
 	local ip="${2:-4}"
 	local tables
@@ -1026,7 +1026,7 @@ do_transfer()
 	:> "$sout"
 	:> "$capout"
 
-	if [ $capture -eq 1 ]; then
+	if $capture; then
 		local capuser
 		if [ -z $SUDO_USER ] ; then
 			capuser=""
@@ -1128,7 +1128,7 @@ do_transfer()
 	wait $spid
 	local rets=$?
 
-	if [ $capture -eq 1 ]; then
+	if $capture; then
 	    sleep 1
 	    kill $cappid
 	fi
@@ -1516,7 +1516,7 @@ chk_join_nr()
 	else
 		print_ok
 	fi
-	if [ $validate_checksum -eq 1 ]; then
+	if $validate_checksum; then
 		chk_csum_nr $csum_ns1 $csum_ns2
 		chk_fail_nr $fail_nr $fail_nr
 		chk_rst_nr $rst_nr $rst_nr
@@ -3944,10 +3944,10 @@ while getopts "${all_tests_args}cCih" opt; do
 			tests+=("${all_tests[${opt}]}")
 			;;
 		c)
-			capture=1
+			capture=true
 			;;
 		C)
-			checksum=1
+			checksum=true
 			;;
 		i)
 			ip_mptcp=1
diff --git a/tools/testing/selftests/net/mptcp/pm_netlink.sh b/tools/testing/selftests/net/mptcp/pm_netlink.sh
index 71899a3ffa7a9d7831c61f08b7f3b9c20aaed58e..ebfefae71e136008701829bc3d528d18a763fd0a 100755
--- a/tools/testing/selftests/net/mptcp/pm_netlink.sh
+++ b/tools/testing/selftests/net/mptcp/pm_netlink.sh
@@ -28,7 +28,6 @@ sec=$(date +%s)
 rndh=$(printf %x $sec)-$(mktemp -u XXXXXX)
 ns1="ns1-$rndh"
 err=$(mktemp)
-ret=0
 
 cleanup()
 {
diff --git a/tools/testing/selftests/net/mptcp/simult_flows.sh b/tools/testing/selftests/net/mptcp/simult_flows.sh
index 214a89fce8b803663b7a7f175474bf627f9b2264..6458e26ab5f4fa3a4ca3536fd486c50004a813ca 100755
--- a/tools/testing/selftests/net/mptcp/simult_flows.sh
+++ b/tools/testing/selftests/net/mptcp/simult_flows.sh
@@ -16,6 +16,12 @@ test_cnt=1
 ret=0
 bail=0
 slack=50
+large=""
+small=""
+sout=""
+cout=""
+capout=""
+size=0
 
 usage() {
 	echo "Usage: $0 [ -b ] [ -c ] [ -d ]"