Subject: [PATCH v2 net-next] selftests: Add debugging options to pmtu.sh

From: David Ahern <[email-masked]>
Date: Thu, 11 Apr 2019 11:51:50 -0700

From: David Ahern <[email-masked]>

pmtu.sh script runs a number of tests and dumps a summary of pass/fail.
If a test fails, it is near impossible to debug why. For example:

    TEST: ipv6: PMTU exceptions                       [FAIL]

There are a lot of commands run behind the scenes for this test. Which
one is failing?

Add a VERBOSE option to show commands that are run and any output from
those commands. Add a PAUSE_ON_FAIL option to halt the script if a test
fails allowing users to poke around with the setup in the failed state.

In the process, rename tracing to TRACING and move declaration to top
with the new variables.

Signed-off-by: David Ahern <[email-masked]>
---
v2
- moved tracing to TRACING, dropped eval and quoted command in new run_cmd,
  dropped local from declarations - all comments from Stefano

 tools/testing/selftests/net/pmtu.sh | 213 +++++++++++++++++++++---------------
 1 file changed, 124 insertions(+), 89 deletions(-)

diff --git a/tools/testing/selftests/net/pmtu.sh b/tools/testing/selftests/net/pmtu.sh
index 912b2dc50be3..524b15dabb3c 100755
--- a/tools/testing/selftests/net/pmtu.sh
+++ b/tools/testing/selftests/net/pmtu.sh
@@ -116,6 +116,10 @@
 # Kselftest framework requirement - SKIP code is 4.
 ksft_skip=4
 
+PAUSE_ON_FAIL=no
+VERBOSE=0
+TRACING=0
+
 # Some systems don't have a ping6 binary anymore
 which ping6 > /dev/null 2>&1 && ping6=$(which ping6) || ping6=$(which ping)
 
@@ -222,6 +226,23 @@ err_flush() {
 	err_buf=
 }
 
+run_cmd() {
+	cmd="$*"
+
+	if [ "$VERBOSE" = "1" ]; then
+		printf "    COMMAND: $cmd\n"
+	fi
+
+	out="$($cmd 2>&1)"
+	rc=$?
+	if [ "$VERBOSE" = "1" -a -n "$out" ]; then
+		echo "    $out"
+		echo
+	fi
+
+	return $rc
+}
+
 # Find the auto-generated name for this namespace
 nsname() {
 	eval echo \$NS_$1
@@ -258,22 +279,22 @@ setup_fou_or_gue() {
 		fi
 	fi
 
-	${ns_a} ip fou add port 5555 ipproto ${ipproto} || return 2
-	${ns_a} ip link add ${encap}_a type ${type} ${mode} local ${a_addr} remote ${b_addr} encap ${encap} encap-sport auto encap-dport 5556 || return 2
+	run_cmd ${ns_a} ip fou add port 5555 ipproto ${ipproto} || return 2
+	run_cmd ${ns_a} ip link add ${encap}_a type ${type} ${mode} local ${a_addr} remote ${b_addr} encap ${encap} encap-sport auto encap-dport 5556 || return 2
 
-	${ns_b} ip fou add port 5556 ipproto ${ipproto}
-	${ns_b} ip link add ${encap}_b type ${type} ${mode} local ${b_addr} remote ${a_addr} encap ${encap} encap-sport auto encap-dport 5555
+	run_cmd ${ns_b} ip fou add port 5556 ipproto ${ipproto}
+	run_cmd ${ns_b} ip link add ${encap}_b type ${type} ${mode} local ${b_addr} remote ${a_addr} encap ${encap} encap-sport auto encap-dport 5555
 
 	if [ "${inner}" = "4" ]; then
-		${ns_a} ip addr add ${tunnel4_a_addr}/${tunnel4_mask} dev ${encap}_a
-		${ns_b} ip addr add ${tunnel4_b_addr}/${tunnel4_mask} dev ${encap}_b
+		run_cmd ${ns_a} ip addr add ${tunnel4_a_addr}/${tunnel4_mask} dev ${encap}_a
+		run_cmd ${ns_b} ip addr add ${tunnel4_b_addr}/${tunnel4_mask} dev ${encap}_b
 	else
-		${ns_a} ip addr add ${tunnel6_a_addr}/${tunnel6_mask} dev ${encap}_a
-		${ns_b} ip addr add ${tunnel6_b_addr}/${tunnel6_mask} dev ${encap}_b
+		run_cmd ${ns_a} ip addr add ${tunnel6_a_addr}/${tunnel6_mask} dev ${encap}_a
+		run_cmd ${ns_b} ip addr add ${tunnel6_b_addr}/${tunnel6_mask} dev ${encap}_b
 	fi
 
-	${ns_a} ip link set ${encap}_a up
-	${ns_b} ip link set ${encap}_b up
+	run_cmd ${ns_a} ip link set ${encap}_a up
+	run_cmd ${ns_b} ip link set ${encap}_b up
 }
 
 setup_fou44() {
@@ -319,17 +340,17 @@ setup_namespaces() {
 }
 
 setup_veth() {
-	${ns_a} ip link add veth_a type veth peer name veth_b || return 1
-	${ns_a} ip link set veth_b netns ${NS_B}
+	run_cmd ${ns_a} ip link add veth_a type veth peer name veth_b || return 1
+	run_cmd ${ns_a} ip link set veth_b netns ${NS_B}
 
-	${ns_a} ip addr add ${veth4_a_addr}/${veth4_mask} dev veth_a
-	${ns_b} ip addr add ${veth4_b_addr}/${veth4_mask} dev veth_b
+	run_cmd ${ns_a} ip addr add ${veth4_a_addr}/${veth4_mask} dev veth_a
+	run_cmd ${ns_b} ip addr add ${veth4_b_addr}/${veth4_mask} dev veth_b
 
-	${ns_a} ip addr add ${veth6_a_addr}/${veth6_mask} dev veth_a
-	${ns_b} ip addr add ${veth6_b_addr}/${veth6_mask} dev veth_b
+	run_cmd ${ns_a} ip addr add ${veth6_a_addr}/${veth6_mask} dev veth_a
+	run_cmd ${ns_b} ip addr add ${veth6_b_addr}/${veth6_mask} dev veth_b
 
-	${ns_a} ip link set veth_a up
-	${ns_b} ip link set veth_b up
+	run_cmd ${ns_a} ip link set veth_a up
+	run_cmd ${ns_b} ip link set veth_b up
 }
 
 setup_vti() {
@@ -342,14 +363,14 @@ setup_vti() {
 
 	[ ${proto} -eq 6 ] && vti_type="vti6" || vti_type="vti"
 
-	${ns_a} ip link add vti${proto}_a type ${vti_type} local ${veth_a_addr} remote ${veth_b_addr} key 10 || return 1
-	${ns_b} ip link add vti${proto}_b type ${vti_type} local ${veth_b_addr} remote ${veth_a_addr} key 10
+	run_cmd ${ns_a} ip link add vti${proto}_a type ${vti_type} local ${veth_a_addr} remote ${veth_b_addr} key 10 || return 1
+	run_cmd ${ns_b} ip link add vti${proto}_b type ${vti_type} local ${veth_b_addr} remote ${veth_a_addr} key 10
 
-	${ns_a} ip addr add ${vti_a_addr}/${vti_mask} dev vti${proto}_a
-	${ns_b} ip addr add ${vti_b_addr}/${vti_mask} dev vti${proto}_b
+	run_cmd ${ns_a} ip addr add ${vti_a_addr}/${vti_mask} dev vti${proto}_a
+	run_cmd ${ns_b} ip addr add ${vti_b_addr}/${vti_mask} dev vti${proto}_b
 
-	${ns_a} ip link set vti${proto}_a up
-	${ns_b} ip link set vti${proto}_b up
+	run_cmd ${ns_a} ip link set vti${proto}_a up
+	run_cmd ${ns_b} ip link set vti${proto}_b up
 }
 
 setup_vti4() {
@@ -375,17 +396,17 @@ setup_vxlan_or_geneve() {
 		opts_b=""
 	fi
 
-	${ns_a} ip link add ${type}_a type ${type} id 1 ${opts_a} remote ${b_addr} ${opts} || return 1
-	${ns_b} ip link add ${type}_b type ${type} id 1 ${opts_b} remote ${a_addr} ${opts}
+	run_cmd ${ns_a} ip link add ${type}_a type ${type} id 1 ${opts_a} remote ${b_addr} ${opts} || return 1
+	run_cmd ${ns_b} ip link add ${type}_b type ${type} id 1 ${opts_b} remote ${a_addr} ${opts}
 
-	${ns_a} ip addr add ${tunnel4_a_addr}/${tunnel4_mask} dev ${type}_a
-	${ns_b} ip addr add ${tunnel4_b_addr}/${tunnel4_mask} dev ${type}_b
+	run_cmd ${ns_a} ip addr add ${tunnel4_a_addr}/${tunnel4_mask} dev ${type}_a
+	run_cmd ${ns_b} ip addr add ${tunnel4_b_addr}/${tunnel4_mask} dev ${type}_b
 
-	${ns_a} ip addr add ${tunnel6_a_addr}/${tunnel6_mask} dev ${type}_a
-	${ns_b} ip addr add ${tunnel6_b_addr}/${tunnel6_mask} dev ${type}_b
+	run_cmd ${ns_a} ip addr add ${tunnel6_a_addr}/${tunnel6_mask} dev ${type}_a
+	run_cmd ${ns_b} ip addr add ${tunnel6_b_addr}/${tunnel6_mask} dev ${type}_b
 
-	${ns_a} ip link set ${type}_a up
-	${ns_b} ip link set ${type}_b up
+	run_cmd ${ns_a} ip link set ${type}_a up
+	run_cmd ${ns_b} ip link set ${type}_b up
 }
 
 setup_geneve4() {
@@ -409,15 +430,15 @@ setup_xfrm() {
 	veth_a_addr="${2}"
 	veth_b_addr="${3}"
 
-	${ns_a} ip -${proto} xfrm state add src ${veth_a_addr} dst ${veth_b_addr} spi 0x1000 proto esp aead "rfc4106(gcm(aes))" 0x0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f 128 mode tunnel || return 1
-	${ns_a} ip -${proto} xfrm state add src ${veth_b_addr} dst ${veth_a_addr} spi 0x1001 proto esp aead "rfc4106(gcm(aes))" 0x0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f 128 mode tunnel
-	${ns_a} ip -${proto} xfrm policy add dir out mark 10 tmpl src ${veth_a_addr} dst ${veth_b_addr} proto esp mode tunnel
-	${ns_a} ip -${proto} xfrm policy add dir in mark 10 tmpl src ${veth_b_addr} dst ${veth_a_addr} proto esp mode tunnel
+	run_cmd "${ns_a} ip -${proto} xfrm state add src ${veth_a_addr} dst ${veth_b_addr} spi 0x1000 proto esp aead 'rfc4106(gcm(aes))' 0x0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f 128 mode tunnel" || return 1
+	run_cmd "${ns_a} ip -${proto} xfrm state add src ${veth_b_addr} dst ${veth_a_addr} spi 0x1001 proto esp aead 'rfc4106(gcm(aes))' 0x0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f 128 mode tunnel"
+	run_cmd "${ns_a} ip -${proto} xfrm policy add dir out mark 10 tmpl src ${veth_a_addr} dst ${veth_b_addr} proto esp mode tunnel"
+	run_cmd "${ns_a} ip -${proto} xfrm policy add dir in mark 10 tmpl src ${veth_b_addr} dst ${veth_a_addr} proto esp mode tunnel"
 
-	${ns_b} ip -${proto} xfrm state add src ${veth_a_addr} dst ${veth_b_addr} spi 0x1000 proto esp aead "rfc4106(gcm(aes))" 0x0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f 128 mode tunnel
-	${ns_b} ip -${proto} xfrm state add src ${veth_b_addr} dst ${veth_a_addr} spi 0x1001 proto esp aead "rfc4106(gcm(aes))" 0x0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f 128 mode tunnel
-	${ns_b} ip -${proto} xfrm policy add dir out mark 10 tmpl src ${veth_b_addr} dst ${veth_a_addr} proto esp mode tunnel
-	${ns_b} ip -${proto} xfrm policy add dir in mark 10 tmpl src ${veth_a_addr} dst ${veth_b_addr} proto esp mode tunnel
+	run_cmd "${ns_b} ip -${proto} xfrm state add src ${veth_a_addr} dst ${veth_b_addr} spi 0x1000 proto esp aead 'rfc4106(gcm(aes))' 0x0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f 128 mode tunnel"
+	run_cmd "${ns_b} ip -${proto} xfrm state add src ${veth_b_addr} dst ${veth_a_addr} spi 0x1001 proto esp aead 'rfc4106(gcm(aes))' 0x0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f0f 128 mode tunnel"
+	run_cmd "${ns_b} ip -${proto} xfrm policy add dir out mark 10 tmpl src ${veth_b_addr} dst ${veth_a_addr} proto esp mode tunnel"
+	run_cmd "${ns_b} ip -${proto} xfrm policy add dir in mark 10 tmpl src ${veth_a_addr} dst ${veth_b_addr} proto esp mode tunnel"
 }
 
 setup_xfrm4() {
@@ -481,7 +502,7 @@ setup() {
 }
 
 trace() {
-	[ $tracing -eq 0 ] && return
+	[ $TRACING -eq 0 ] && return
 
 	for arg do
 		[ "${ns_cmd}" = "" ] && ns_cmd="${arg}" && continue
@@ -597,8 +618,8 @@ test_pmtu_ipvX() {
 	mtu "${ns_b}"  veth_B-R2 1500
 
 	# Create route exceptions
-	${ns_a} ${ping} -q -M want -i 0.1 -w 1 -s 1800 ${dst1} > /dev/null
-	${ns_a} ${ping} -q -M want -i 0.1 -w 1 -s 1800 ${dst2} > /dev/null
+	run_cmd ${ns_a} ${ping} -q -M want -i 0.1 -w 1 -s 1800 ${dst1}
+	run_cmd ${ns_a} ${ping} -q -M want -i 0.1 -w 1 -s 1800 ${dst2}
 
 	# Check that exceptions have been created with the correct PMTU
 	pmtu_1="$(route_get_dst_pmtu_from_exception "${ns_a}" ${dst1})"
@@ -630,7 +651,7 @@ test_pmtu_ipvX() {
 	# Decrease remote MTU on path via R2, get new exception
 	mtu "${ns_r2}" veth_R2-B 400
 	mtu "${ns_b}"  veth_B-R2 400
-	${ns_a} ${ping} -q -M want -i 0.1 -w 1 -s 1400 ${dst2} > /dev/null
+	run_cmd ${ns_a} ${ping} -q -M want -i 0.1 -w 1 -s 1400 ${dst2}
 	pmtu_2="$(route_get_dst_pmtu_from_exception "${ns_a}" ${dst2})"
 	check_pmtu_value "lock 552" "${pmtu_2}" "exceeding MTU, with MTU < min_pmtu" || return 1
 
@@ -647,7 +668,7 @@ test_pmtu_ipvX() {
 	check_pmtu_value "1500" "${pmtu_2}" "increasing local MTU" || return 1
 
 	# Get new exception
-	${ns_a} ${ping} -q -M want -i 0.1 -w 1 -s 1400 ${dst2} > /dev/null
+	run_cmd ${ns_a} ${ping} -q -M want -i 0.1 -w 1 -s 1400 ${dst2}
 	pmtu_2="$(route_get_dst_pmtu_from_exception "${ns_a}" ${dst2})"
 	check_pmtu_value "lock 552" "${pmtu_2}" "exceeding MTU, with MTU < min_pmtu" || return 1
 }
@@ -696,7 +717,7 @@ test_pmtu_ipvX_over_vxlanY_or_geneveY_exception() {
 
 	mtu "${ns_a}" ${type}_a $((${ll_mtu} + 1000))
 	mtu "${ns_b}" ${type}_b $((${ll_mtu} + 1000))
-	${ns_a} ${ping} -q -M want -i 0.1 -w 1 -s $((${ll_mtu} + 500)) ${dst} > /dev/null
+	run_cmd ${ns_a} ${ping} -q -M want -i 0.1 -w 1 -s $((${ll_mtu} + 500)) ${dst}
 
 	# Check that exception was created
 	pmtu="$(route_get_dst_pmtu_from_exception "${ns_a}" ${dst})"
@@ -776,7 +797,7 @@ test_pmtu_ipvX_over_fouY_or_gueY() {
 
 	mtu "${ns_a}" ${encap}_a $((${ll_mtu} + 1000))
 	mtu "${ns_b}" ${encap}_b $((${ll_mtu} + 1000))
-	${ns_a} ${ping} -q -M want -i 0.1 -w 1 -s $((${ll_mtu} + 500)) ${dst} > /dev/null
+	run_cmd ${ns_a} ${ping} -q -M want -i 0.1 -w 1 -s $((${ll_mtu} + 500)) ${dst}
 
 	# Check that exception was created
 	pmtu="$(route_get_dst_pmtu_from_exception "${ns_a}" ${dst})"
@@ -834,13 +855,13 @@ test_pmtu_vti4_exception() {
 
 	# Send DF packet without exceeding link layer MTU, check that no
 	# exception is created
-	${ns_a} ping -q -M want -i 0.1 -w 1 -s ${ping_payload} ${tunnel4_b_addr} > /dev/null
+	run_cmd ${ns_a} ping -q -M want -i 0.1 -w 1 -s ${ping_payload} ${tunnel4_b_addr}
 	pmtu="$(route_get_dst_pmtu_from_exception "${ns_a}" ${tunnel4_b_addr})"
 	check_pmtu_value "" "${pmtu}" "sending packet smaller than PMTU (IP payload length ${esp_payload_rfc4106})" || return 1
 
 	# Now exceed link layer MTU by one byte, check that exception is created
 	# with the right PMTU value
-	${ns_a} ping -q -M want -i 0.1 -w 1 -s $((ping_payload + 1)) ${tunnel4_b_addr} > /dev/null
+	run_cmd ${ns_a} ping -q -M want -i 0.1 -w 1 -s $((ping_payload + 1)) ${tunnel4_b_addr}
 	pmtu="$(route_get_dst_pmtu_from_exception "${ns_a}" ${tunnel4_b_addr})"
 	check_pmtu_value "${esp_payload_rfc4106}" "${pmtu}" "exceeding PMTU (IP payload length $((esp_payload_rfc4106 + 1)))"
 }
@@ -856,7 +877,7 @@ test_pmtu_vti6_exception() {
 	mtu "${ns_b}" veth_b 4000
 	mtu "${ns_a}" vti6_a 5000
 	mtu "${ns_b}" vti6_b 5000
-	${ns_a} ${ping6} -q -i 0.1 -w 1 -s 60000 ${tunnel6_b_addr} > /dev/null
+	run_cmd ${ns_a} ${ping6} -q -i 0.1 -w 1 -s 60000 ${tunnel6_b_addr}
 
 	# Check that exception was created
 	pmtu="$(route_get_dst_pmtu_from_exception "${ns_a}" ${tunnel6_b_addr})"
@@ -902,9 +923,9 @@ test_pmtu_vti6_default_mtu() {
 test_pmtu_vti4_link_add_mtu() {
 	setup namespaces || return 2
 
-	${ns_a} ip link add vti4_a type vti local ${veth4_a_addr} remote ${veth4_b_addr} key 10
+	run_cmd ${ns_a} ip link add vti4_a type vti local ${veth4_a_addr} remote ${veth4_b_addr} key 10
 	[ $? -ne 0 ] && err "  vti not supported" && return 2
-	${ns_a} ip link del vti4_a
+	run_cmd ${ns_a} ip link del vti4_a
 
 	fail=0
 
@@ -912,7 +933,7 @@ test_pmtu_vti4_link_add_mtu() {
 	max=$((65535 - 20))
 	# Check invalid values first
 	for v in $((min - 1)) $((max + 1)); do
-		${ns_a} ip link add vti4_a mtu ${v} type vti local ${veth4_a_addr} remote ${veth4_b_addr} key 10 2>/dev/null
+		run_cmd ${ns_a} ip link add vti4_a mtu ${v} type vti local ${veth4_a_addr} remote ${veth4_b_addr} key 10
 		# This can fail, or MTU can be adjusted to a proper value
 		[ $? -ne 0 ] && continue
 		mtu="$(link_get_mtu "${ns_a}" vti4_a)"
@@ -920,14 +941,14 @@ test_pmtu_vti4_link_add_mtu() {
 			err "  vti tunnel created with invalid MTU ${mtu}"
 			fail=1
 		fi
-		${ns_a} ip link del vti4_a
+		run_cmd ${ns_a} ip link del vti4_a
 	done
 
 	# Now check valid values
 	for v in ${min} 1300 ${max}; do
-		${ns_a} ip link add vti4_a mtu ${v} type vti local ${veth4_a_addr} remote ${veth4_b_addr} key 10
+		run_cmd ${ns_a} ip link add vti4_a mtu ${v} type vti local ${veth4_a_addr} remote ${veth4_b_addr} key 10
 		mtu="$(link_get_mtu "${ns_a}" vti4_a)"
-		${ns_a} ip link del vti4_a
+		run_cmd ${ns_a} ip link del vti4_a
 		if [ "${mtu}" != "${v}" ]; then
 			err "  vti MTU ${mtu} doesn't match configured value ${v}"
 			fail=1
@@ -940,9 +961,9 @@ test_pmtu_vti4_link_add_mtu() {
 test_pmtu_vti6_link_add_mtu() {
 	setup namespaces || return 2
 
-	${ns_a} ip link add vti6_a type vti6 local ${veth6_a_addr} remote ${veth6_b_addr} key 10
+	run_cmd ${ns_a} ip link add vti6_a type vti6 local ${veth6_a_addr} remote ${veth6_b_addr} key 10
 	[ $? -ne 0 ] && err "  vti6 not supported" && return 2
-	${ns_a} ip link del vti6_a
+	run_cmd ${ns_a} ip link del vti6_a
 
 	fail=0
 
@@ -950,7 +971,7 @@ test_pmtu_vti6_link_add_mtu() {
 	max=$((65535 - 40))
 	# Check invalid values first
 	for v in $((min - 1)) $((max + 1)); do
-		${ns_a} ip link add vti6_a mtu ${v} type vti6 local ${veth6_a_addr} remote ${veth6_b_addr} key 10 2>/dev/null
+		run_cmd ${ns_a} ip link add vti6_a mtu ${v} type vti6 local ${veth6_a_addr} remote ${veth6_b_addr} key 10
 		# This can fail, or MTU can be adjusted to a proper value
 		[ $? -ne 0 ] && continue
 		mtu="$(link_get_mtu "${ns_a}" vti6_a)"
@@ -958,14 +979,14 @@ test_pmtu_vti6_link_add_mtu() {
 			err "  vti6 tunnel created with invalid MTU ${v}"
 			fail=1
 		fi
-		${ns_a} ip link del vti6_a
+		run_cmd ${ns_a} ip link del vti6_a
 	done
 
 	# Now check valid values
 	for v in 68 1280 1300 $((65535 - 40)); do
-		${ns_a} ip link add vti6_a mtu ${v} type vti6 local ${veth6_a_addr} remote ${veth6_b_addr} key 10
+		run_cmd ${ns_a} ip link add vti6_a mtu ${v} type vti6 local ${veth6_a_addr} remote ${veth6_b_addr} key 10
 		mtu="$(link_get_mtu "${ns_a}" vti6_a)"
-		${ns_a} ip link del vti6_a
+		run_cmd ${ns_a} ip link del vti6_a
 		if [ "${mtu}" != "${v}" ]; then
 			err "  vti6 MTU ${mtu} doesn't match configured value ${v}"
 			fail=1
@@ -978,19 +999,19 @@ test_pmtu_vti6_link_add_mtu() {
 test_pmtu_vti6_link_change_mtu() {
 	setup namespaces || return 2
 
-	${ns_a} ip link add dummy0 mtu 1500 type dummy
+	run_cmd ${ns_a} ip link add dummy0 mtu 1500 type dummy
 	[ $? -ne 0 ] && err "  dummy not supported" && return 2
-	${ns_a} ip link add dummy1 mtu 3000 type dummy
-	${ns_a} ip link set dummy0 up
-	${ns_a} ip link set dummy1 up
+	run_cmd ${ns_a} ip link add dummy1 mtu 3000 type dummy
+	run_cmd ${ns_a} ip link set dummy0 up
+	run_cmd ${ns_a} ip link set dummy1 up
 
-	${ns_a} ip addr add ${dummy6_0_addr}/${dummy6_mask} dev dummy0
-	${ns_a} ip addr add ${dummy6_1_addr}/${dummy6_mask} dev dummy1
+	run_cmd ${ns_a} ip addr add ${dummy6_0_addr}/${dummy6_mask} dev dummy0
+	run_cmd ${ns_a} ip addr add ${dummy6_1_addr}/${dummy6_mask} dev dummy1
 
 	fail=0
 
 	# Create vti6 interface bound to device, passing MTU, check it
-	${ns_a} ip link add vti6_a mtu 1300 type vti6 remote ${dummy6_0_addr} local ${dummy6_0_addr}
+	run_cmd ${ns_a} ip link add vti6_a mtu 1300 type vti6 remote ${dummy6_0_addr} local ${dummy6_0_addr}
 	mtu="$(link_get_mtu "${ns_a}" vti6_a)"
 	if [ ${mtu} -ne 1300 ]; then
 		err "  vti6 MTU ${mtu} doesn't match configured value 1300"
@@ -999,7 +1020,7 @@ test_pmtu_vti6_link_change_mtu() {
 
 	# Move to another device with different MTU, without passing MTU, check
 	# MTU is adjusted
-	${ns_a} ip link set vti6_a type vti6 remote ${dummy6_1_addr} local ${dummy6_1_addr}
+	run_cmd ${ns_a} ip link set vti6_a type vti6 remote ${dummy6_1_addr} local ${dummy6_1_addr}
 	mtu="$(link_get_mtu "${ns_a}" vti6_a)"
 	if [ ${mtu} -ne $((3000 - 40)) ]; then
 		err "  vti MTU ${mtu} is not dummy MTU 3000 minus IPv6 header length"
@@ -1007,7 +1028,7 @@ test_pmtu_vti6_link_change_mtu() {
 	fi
 
 	# Move it back, passing MTU, check MTU is not overridden
-	${ns_a} ip link set vti6_a mtu 1280 type vti6 remote ${dummy6_0_addr} local ${dummy6_0_addr}
+	run_cmd ${ns_a} ip link set vti6_a mtu 1280 type vti6 remote ${dummy6_0_addr} local ${dummy6_0_addr}
 	mtu="$(link_get_mtu "${ns_a}" vti6_a)"
 	if [ ${mtu} -ne 1280 ]; then
 		err "  vti6 MTU ${mtu} doesn't match configured value 1280"
@@ -1052,7 +1073,7 @@ test_cleanup_vxlanX_exception() {
 	# Fill exception cache for multiple CPUs (2)
 	# we can always use inner IPv4 for that
 	for cpu in ${cpu_list}; do
-		taskset --cpu-list ${cpu} ${ns_a} ping -q -M want -i 0.1 -w 1 -s $((${ll_mtu} + 500)) ${tunnel4_b_addr} > /dev/null
+		run_cmd taskset --cpu-list ${cpu} ${ns_a} ping -q -M want -i 0.1 -w 1 -s $((${ll_mtu} + 500)) ${tunnel4_b_addr}
 	done
 
 	${ns_a} ip link del dev veth_A-R1 &
@@ -1084,29 +1105,33 @@ usage() {
 	exit 1
 }
 
+################################################################################
+#
 exitcode=0
 desc=0
+
+while getopts :ptv o
+do
+	case $o in
+	p) PAUSE_ON_FAIL=yes;;
+	v) VERBOSE=1;;
+	t) if which tcpdump > /dev/null 2>&1; then
+		TRACING=1
+	   else
+		echo "=== tcpdump not available, tracing disabled"
+	   fi
+	   ;;
+	*) usage;;
+	esac
+done
+shift $(($OPTIND-1))
+
 IFS="	
 "
 
-tracing=0
 for arg do
-	if [ "${arg}" != "${arg#--*}" ]; then
-		opt="${arg#--}"
-		if [ "${opt}" = "trace" ]; then
-			if which tcpdump > /dev/null 2>&1; then
-				tracing=1
-			else
-				echo "=== tcpdump not available, tracing disabled"
-			fi
-		else
-			usage
-		fi
-	else
-		# Check first that all requested tests are available before
-		# running any
-		command -v > /dev/null "test_${arg}" || { echo "=== Test ${arg} not found"; usage; }
-	fi
+	# Check first that all requested tests are available before running any
+	command -v > /dev/null "test_${arg}" || { echo "=== Test ${arg} not found"; usage; }
 done
 
 trap cleanup EXIT
@@ -1124,6 +1149,11 @@ for t in ${tests}; do
 
 	(
 		unset IFS
+
+		if [ "$VERBOSE" = "1" ]; then
+			printf "\n##########################################################################\n\n"
+		fi
+
 		eval test_${name}
 		ret=$?
 		cleanup
@@ -1132,6 +1162,11 @@ for t in ${tests}; do
 			printf "TEST: %-60s  [ OK ]\n" "${t}"
 		elif [ $ret -eq 1 ]; then
 			printf "TEST: %-60s  [FAIL]\n" "${t}"
+			if [ "${PAUSE_ON_FAIL}" = "yes" ]; then
+				echo
+				echo "Pausing. Hit enter to continue"
+				read a
+			fi
 			err_flush
 			exit 1
 		elif [ $ret -eq 2 ]; then
-- 
2.11.0