9 files changed, 80 insertions, 3 deletions
diff --git a/tools/testing/selftests/net/mptcp/Makefile b/tools/testing/selftests/net/mptcp/Makefile
index 43a723626126..7b936a926859 100644
--- a/tools/testing/selftests/net/mptcp/Makefile
+++ b/tools/testing/selftests/net/mptcp/Makefile
@@ -9,7 +9,7 @@ TEST_PROGS := mptcp_connect.sh pm_netlink.sh mptcp_join.sh diag.sh \
 
 TEST_GEN_FILES = mptcp_connect pm_nl_ctl mptcp_sockopt mptcp_inq
 
-TEST_FILES := settings
+TEST_FILES := mptcp_lib.sh settings
 
 EXTRA_CLEAN := *.pcap
 
diff --git a/tools/testing/selftests/net/mptcp/diag.sh b/tools/testing/selftests/net/mptcp/diag.sh
index ef628b16fe9b..4eacdb1ab962 100755
--- a/tools/testing/selftests/net/mptcp/diag.sh
+++ b/tools/testing/selftests/net/mptcp/diag.sh
@@ -1,6 +1,8 @@
 #!/bin/bash
 # SPDX-License-Identifier: GPL-2.0
 
+. "$(dirname "${0}")/mptcp_lib.sh"
+
 sec=$(date +%s)
 rndh=$(printf %x $sec)-$(mktemp -u XXXXXX)
 ns="ns1-$rndh"
@@ -31,6 +33,8 @@ cleanup()
 	ip netns del $ns
 }
 
+mptcp_lib_check_mptcp
+
 ip -Version > /dev/null 2>&1
 if [ $? -ne 0 ];then
 	echo "SKIP: Could not run test without ip tool"
diff --git a/tools/testing/selftests/net/mptcp/mptcp_connect.sh b/tools/testing/selftests/net/mptcp/mptcp_connect.sh
index a43d3e2f59bb..c1f7bac19942 100755
--- a/tools/testing/selftests/net/mptcp/mptcp_connect.sh
+++ b/tools/testing/selftests/net/mptcp/mptcp_connect.sh
@@ -1,6 +1,8 @@
 #!/bin/bash
 # SPDX-License-Identifier: GPL-2.0
 
+. "$(dirname "${0}")/mptcp_lib.sh"
+
 time_start=$(date +%s)
 
 optstring="S:R:d:e:l:r:h4cm:f:tC"
@@ -141,6 +143,8 @@ cleanup()
 	done
 }
 
+mptcp_lib_check_mptcp
+
 ip -Version > /dev/null 2>&1
 if [ $? -ne 0 ];then
 	echo "SKIP: Could not run test without ip tool"
diff --git a/tools/testing/selftests/net/mptcp/mptcp_join.sh b/tools/testing/selftests/net/mptcp/mptcp_join.sh
index 26310c17b4c6..96f63172b8fe 100755
--- a/tools/testing/selftests/net/mptcp/mptcp_join.sh
+++ b/tools/testing/selftests/net/mptcp/mptcp_join.sh
@@ -10,6 +10,8 @@
 # because it's invoked by variable name, see how the "tests" array is used
 #shellcheck disable=SC2317
 
+. "$(dirname "${0}")/mptcp_lib.sh"
+
 ret=0
 sin=""
 sinfail=""
@@ -17,6 +19,7 @@ sout=""
 cin=""
 cinfail=""
 cinsent=""
+tmpfile=""
 cout=""
 capout=""
 ns1=""
@@ -136,6 +139,8 @@ cleanup_partial()
 
 check_tools()
 {
+	mptcp_lib_check_mptcp
+
 	if ! ip -Version &> /dev/null; then
 		echo "SKIP: Could not run test without ip tool"
 		exit $ksft_skip
@@ -175,6 +180,7 @@ cleanup()
 {
 	rm -f "$cin" "$cout" "$sinfail"
 	rm -f "$sin" "$sout" "$cinsent" "$cinfail"
+	rm -f "$tmpfile"
 	rm -rf $evts_ns1 $evts_ns2
 	cleanup_partial
 }
@@ -383,9 +389,16 @@ check_transfer()
 			fail_test
 			return 1
 		fi
-		bytes="--bytes=${bytes}"
+
+		# note: BusyBox's "cmp" command doesn't support --bytes
+		tmpfile=$(mktemp)
+		head --bytes="$bytes" "$in" > "$tmpfile"
+		mv "$tmpfile" "$in"
+		head --bytes="$bytes" "$out" > "$tmpfile"
+		mv "$tmpfile" "$out"
+		tmpfile=""
 	fi
-	cmp -l "$in" "$out" ${bytes} | while read -r i a b; do
+	cmp -l "$in" "$out" | while read -r i a b; do
 		local sum=$((0${a} + 0${b}))
 		if [ $check_invert -eq 0 ] || [ $sum -ne $((0xff)) ]; then
 			echo "[ FAIL ] $what does not match (in, out):"
diff --git a/tools/testing/selftests/net/mptcp/mptcp_lib.sh b/tools/testing/selftests/net/mptcp/mptcp_lib.sh
new file mode 100644
index 000000000000..3286536b79d5
--- /dev/null
+++ b/tools/testing/selftests/net/mptcp/mptcp_lib.sh
@@ -0,0 +1,40 @@
+#! /bin/bash
+# SPDX-License-Identifier: GPL-2.0
+
+readonly KSFT_FAIL=1
+readonly KSFT_SKIP=4
+
+# SELFTESTS_MPTCP_LIB_EXPECT_ALL_FEATURES env var can be set when validating all
+# features using the last version of the kernel and the selftests to make sure
+# a test is not being skipped by mistake.
+mptcp_lib_expect_all_features() {
+	[ "${SELFTESTS_MPTCP_LIB_EXPECT_ALL_FEATURES:-}" = "1" ]
+}
+
+# $1: msg
+mptcp_lib_fail_if_expected_feature() {
+	if mptcp_lib_expect_all_features; then
+		echo "ERROR: missing feature: ${*}"
+		exit ${KSFT_FAIL}
+	fi
+
+	return 1
+}
+
+# $1: file
+mptcp_lib_has_file() {
+	local f="${1}"
+
+	if [ -f "${f}" ]; then
+		return 0
+	fi
+
+	mptcp_lib_fail_if_expected_feature "${f} file not found"
+}
+
+mptcp_lib_check_mptcp() {
+	if ! mptcp_lib_has_file "/proc/sys/net/mptcp/enabled"; then
+		echo "SKIP: MPTCP support is not available"
+		exit ${KSFT_SKIP}
+	fi
+}
diff --git a/tools/testing/selftests/net/mptcp/mptcp_sockopt.sh b/tools/testing/selftests/net/mptcp/mptcp_sockopt.sh
index 1b70c0a304ce..ff5adbb9c7f2 100755
--- a/tools/testing/selftests/net/mptcp/mptcp_sockopt.sh
+++ b/tools/testing/selftests/net/mptcp/mptcp_sockopt.sh
@@ -1,6 +1,8 @@
 #!/bin/bash
 # SPDX-License-Identifier: GPL-2.0
 
+. "$(dirname "${0}")/mptcp_lib.sh"
+
 ret=0
 sin=""
 sout=""
@@ -84,6 +86,8 @@ cleanup()
 	rm -f "$sin" "$sout"
 }
 
+mptcp_lib_check_mptcp
+
 ip -Version > /dev/null 2>&1
 if [ $? -ne 0 ];then
 	echo "SKIP: Could not run test without ip tool"
diff --git a/tools/testing/selftests/net/mptcp/pm_netlink.sh b/tools/testing/selftests/net/mptcp/pm_netlink.sh
index 89839d1ff9d8..32f7533e0919 100755
--- a/tools/testing/selftests/net/mptcp/pm_netlink.sh
+++ b/tools/testing/selftests/net/mptcp/pm_netlink.sh
@@ -1,6 +1,8 @@
 #!/bin/bash
 # SPDX-License-Identifier: GPL-2.0
 
+. "$(dirname "${0}")/mptcp_lib.sh"
+
 ksft_skip=4
 ret=0
 
@@ -34,6 +36,8 @@ cleanup()
 	ip netns del $ns1
 }
 
+mptcp_lib_check_mptcp
+
 ip -Version > /dev/null 2>&1
 if [ $? -ne 0 ];then
 	echo "SKIP: Could not run test without ip tool"
diff --git a/tools/testing/selftests/net/mptcp/simult_flows.sh b/tools/testing/selftests/net/mptcp/simult_flows.sh
index 9f22f7e5027d..36a3c9d92e20 100755
--- a/tools/testing/selftests/net/mptcp/simult_flows.sh
+++ b/tools/testing/selftests/net/mptcp/simult_flows.sh
@@ -1,6 +1,8 @@
 #!/bin/bash
 # SPDX-License-Identifier: GPL-2.0
 
+. "$(dirname "${0}")/mptcp_lib.sh"
+
 sec=$(date +%s)
 rndh=$(printf %x $sec)-$(mktemp -u XXXXXX)
 ns1="ns1-$rndh"
@@ -34,6 +36,8 @@ cleanup()
 	done
 }
 
+mptcp_lib_check_mptcp
+
 ip -Version > /dev/null 2>&1
 if [ $? -ne 0 ];then
 	echo "SKIP: Could not run test without ip tool"
diff --git a/tools/testing/selftests/net/mptcp/userspace_pm.sh b/tools/testing/selftests/net/mptcp/userspace_pm.sh
index b1eb7bce599d..8092399d911f 100755
--- a/tools/testing/selftests/net/mptcp/userspace_pm.sh
+++ b/tools/testing/selftests/net/mptcp/userspace_pm.sh
@@ -1,6 +1,10 @@
 #!/bin/bash
 # SPDX-License-Identifier: GPL-2.0
 
+. "$(dirname "${0}")/mptcp_lib.sh"
+
+mptcp_lib_check_mptcp
+
 ip -Version > /dev/null 2>&1
 if [ $? -ne 0 ];then
 	echo "SKIP: Cannot not run test without ip tool"