selftests: net: add helper for checking if nettest is available

A few tests check if nettest exists in the $PATH before adding
$PWD to $PATH and re-checking. They don't discard stderr on
the first check (and nettest is built as part of selftests,
so it's pretty normal for it to not be available in system $PATH).
This leads to output noise:

  which: no nettest in (/home/virtme/tools/fs/bin:/home/virtme/tools/fs/sbin:/home/virtme/tools/fs/usr/bin:/home/virtme/tools/fs/usr/sbin:/bin:/sbin:/usr/bin:/usr/sbin:/usr/local/bin)

Add a common helper for the check which does silence stderr.

There is another small functional change hiding here, because pmtu.sh
and fib_rule_tests.sh used to return from the test case rather than
completely exit. Building nettest is not hard, there should be no need
to maintain the ability to selectively skip cases in its absence.
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Reviewed-by: Hangbin Liu <liuhangbin@gmail.com>
Link: https://patch.msgid.link/20240821012227.1398769-1-kuba@kernel.orgSigned-off-by: Paolo Abeni <pabeni@redhat.com>

tools/testing/selftests/net/fcnal-test.sh

@@ -4304,14 +4304,7 @@ elif [ "$TESTS" = "ipv6" ]; then
 	TESTS="$TESTS_IPV6"
 fi
 
-# nettest can be run from PATH or from same directory as this selftest
-if ! which nettest >/dev/null; then
-	PATH=$PWD:$PATH
-	if ! which nettest >/dev/null; then
-		echo "'nettest' command not found; skipping tests"
-		exit $ksft_skip
-	fi
-fi
+check_gen_prog "nettest"
 
 declare -i nfail=0
 declare -i nsuccess=0

tools/testing/selftests/net/fib_rule_tests.sh

@@ -51,31 +51,6 @@ log_test()
 	fi
 }
 
-check_nettest()
-{
-	if which nettest > /dev/null 2>&1; then
-		return 0
-	fi
-
-	# Add the selftest directory to PATH if not already done
-	if [ "${SELFTEST_PATH}" = "" ]; then
-		SELFTEST_PATH="$(dirname $0)"
-		PATH="${PATH}:${SELFTEST_PATH}"
-
-		# Now retry with the new path
-		if which nettest > /dev/null 2>&1; then
-			return 0
-		fi
-
-		if [ "${ret}" -eq 0 ]; then
-			ret="${ksft_skip}"
-		fi
-		echo "nettest not found (try 'make -C ${SELFTEST_PATH} nettest')"
-	fi
-
-	return 1
-}
-
 setup()
 {
 	set -e
@@ -317,11 +292,6 @@ fib_rule6_connect_test()
 	echo
 	echo "IPv6 FIB rule connect tests"
 
-	if ! check_nettest; then
-		echo "SKIP: Could not run test without nettest tool"
-		return
-	fi
-
 	setup_peer
 	$IP -6 rule add dsfield 0x04 table $RTABLE_PEER
 
@@ -516,11 +486,6 @@ fib_rule4_connect_test()
 	echo
 	echo "IPv4 FIB rule connect tests"
 
-	if ! check_nettest; then
-		echo "SKIP: Could not run test without nettest tool"
-		return
-	fi
-
 	setup_peer
 	$IP -4 rule add dsfield 0x04 table $RTABLE_PEER
 
@@ -584,6 +549,8 @@ if [ ! -x "$(command -v ip)" ]; then
 	exit $ksft_skip
 fi
 
+check_gen_prog "nettest"
+
 # start clean
 cleanup &> /dev/null
 setup

tools/testing/selftests/net/lib.sh

@@ -125,6 +125,21 @@ slowwait_for_counter()
 	slowwait "$timeout" until_counter_is ">= $((base + delta))" "$@"
 }
 
+# Check for existence of tools which are built as part of selftests
+# but may also already exist in $PATH
+check_gen_prog()
+{
+	local prog_name=$1; shift
+
+	if ! which $prog_name >/dev/null 2>/dev/null; then
+		PATH=$PWD:$PATH
+		if ! which $prog_name >/dev/null; then
+			echo "'$prog_name' command not found; skipping tests"
+			exit $ksft_skip
+		fi
+	fi
+}
+
 remove_ns_list()
 {
 	local item=$1

tools/testing/selftests/net/pmtu.sh

@@ -681,13 +681,7 @@ setup_xfrm() {
 }
 
 setup_nettest_xfrm() {
-	if ! which nettest >/dev/null; then
-		PATH=$PWD:$PATH
-		if ! which nettest >/dev/null; then
-			echo "'nettest' command not found; skipping tests"
-			return 1
-		fi
-	fi
+	check_gen_prog "nettest"
 
 	[ ${1} -eq 6 ] && proto="-6" || proto=""
 	port=${2}

tools/testing/selftests/net/unicast_extensions.sh

@@ -30,14 +30,7 @@
 
 source lib.sh
 
-# nettest can be run from PATH or from same directory as this selftest
-if ! which nettest >/dev/null; then
-	PATH=$PWD:$PATH
-	if ! which nettest >/dev/null; then
-		echo "'nettest' command not found; skipping tests"
-		exit $ksft_skip
-	fi
-fi
+check_gen_prog "nettest"
 
 result=0
 

tools/testing/selftests/net/vrf_route_leaking.sh

@@ -59,7 +59,6 @@
 # while it is forwarded between different vrfs.
 
 source lib.sh
-PATH=$PWD:$PWD/tools/testing/selftests/net:$PATH
 VERBOSE=0
 PAUSE_ON_FAIL=no
 DEFAULT_TTYPE=sym
@@ -636,6 +635,8 @@ EOF
 # Some systems don't have a ping6 binary anymore
 command -v ping6 > /dev/null 2>&1 && ping6=$(command -v ping6) || ping6=$(command -v ping)
 
+check_gen_prog "nettest"
+
 TESTS_IPV4="ipv4_ping_ttl ipv4_traceroute ipv4_ping_frag ipv4_ping_local ipv4_tcp_local
 ipv4_udp_local ipv4_ping_ttl_asym ipv4_traceroute_asym"
 TESTS_IPV6="ipv6_ping_ttl ipv6_traceroute ipv6_ping_local ipv6_tcp_local ipv6_udp_local