[PATCH net v2 0/2] selftests: pmtu: fix and increase coverage

[PATCH net v2 0/2] selftests: pmtu: fix and increase coverage

[Paolo Abeni]

This series includes a fixup for the pmtu.sh test script, related to IPv6
address management, and adds coverage for the recently reported and fixed
PMTU exception issue

v1 -> v2:
 - several script cleanups

Paolo Abeni (2):
  selftests: pmtu: disable DAD in all namespaces
  selftests: pmtu: add explicit tests for PMTU exceptions cleanup

 tools/testing/selftests/net/pmtu.sh | 95 ++++++++++++++++++++++++-----
 1 file changed, 79 insertions(+), 16 deletions(-)

-- 
2.20.1

[PATCH net v2 1/2] selftests: pmtu: disable DAD in all namespaces

[Paolo Abeni]

Otherwise, the configured IPv6 address could be still "tentative"
at test time, possibly causing tests failures.
We can also drop some sleep along the code and decrease the
timeout for most commands so that the test runtime decreases.

v1 -> v2:
 - fix comment (Stefano)

Fixes: d1f1b9cbf34c ("selftests: net: Introduce first PMTU test")
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: David Ahern <dsahern@gmail.com>
---
 tools/testing/selftests/net/pmtu.sh | 28 +++++++++++++---------------
 1 file changed, 13 insertions(+), 15 deletions(-)

diff --git a/tools/testing/selftests/net/pmtu.sh b/tools/testing/selftests/net/pmtu.sh
index e2c94e47707c..89aec2fdf4fa 100755
--- a/tools/testing/selftests/net/pmtu.sh
+++ b/tools/testing/selftests/net/pmtu.sh
@@ -263,8 +263,6 @@ setup_fou_or_gue() {
 
 	${ns_a} ip link set ${encap}_a up
 	${ns_b} ip link set ${encap}_b up
-
-	sleep 1
 }
 
 setup_fou44() {
@@ -302,6 +300,10 @@ setup_gue66() {
 setup_namespaces() {
 	for n in ${NS_A} ${NS_B} ${NS_R1} ${NS_R2}; do
 		ip netns add ${n} || return 1
+
+		# Disable DAD, so that we don't have to wait to use the
+		# configured IPv6 addresses
+		ip netns exec ${n} sysctl -q net/ipv6/conf/default/accept_dad=0
 	done
 }
 
@@ -337,8 +339,6 @@ setup_vti() {
 
 	${ns_a} ip link set vti${proto}_a up
 	${ns_b} ip link set vti${proto}_b up
-
-	sleep 1
 }
 
 setup_vti4() {
@@ -375,8 +375,6 @@ setup_vxlan_or_geneve() {
 
 	${ns_a} ip link set ${type}_a up
 	${ns_b} ip link set ${type}_b up
-
-	sleep 1
 }
 
 setup_geneve4() {
@@ -588,8 +586,8 @@ test_pmtu_ipvX() {
 	mtu "${ns_b}"  veth_B-R2 1500
 
 	# Create route exceptions
-	${ns_a} ${ping} -q -M want -i 0.1 -w 2 -s 1800 ${dst1} > /dev/null
-	${ns_a} ${ping} -q -M want -i 0.1 -w 2 -s 1800 ${dst2} > /dev/null
+	${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
 
 	# Check that exceptions have been created with the correct PMTU
 	pmtu_1="$(route_get_dst_pmtu_from_exception "${ns_a}" ${dst1})"
@@ -621,7 +619,7 @@ test_pmtu_ipvX() {
 	# Decrease remote MTU on path via R2, get new exception
 	mtu "${ns_r2}" veth_R2-B 400
 	mtu "${ns_b}"  veth_B-R2 400
-	${ns_a} ${ping} -q -M want -i 0.1 -w 2 -s 1400 ${dst2} > /dev/null
+	${ns_a} ${ping} -q -M want -i 0.1 -w 1 -s 1400 ${dst2} > /dev/null
 	pmtu_2="$(route_get_dst_pmtu_from_exception "${ns_a}" ${dst2})"
 	check_pmtu_value "lock 552" "${pmtu_2}" "exceeding MTU, with MTU < min_pmtu" || return 1
 
@@ -638,7 +636,7 @@ 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 2 -s 1400 ${dst2} > /dev/null
+	${ns_a} ${ping} -q -M want -i 0.1 -w 1 -s 1400 ${dst2} > /dev/null
 	pmtu_2="$(route_get_dst_pmtu_from_exception "${ns_a}" ${dst2})"
 	check_pmtu_value "lock 552" "${pmtu_2}" "exceeding MTU, with MTU < min_pmtu" || return 1
 }
@@ -687,7 +685,7 @@ 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 2 -s $((${ll_mtu} + 500)) ${dst} > /dev/null
+	${ns_a} ${ping} -q -M want -i 0.1 -w 1 -s $((${ll_mtu} + 500)) ${dst} > /dev/null
 
 	# Check that exception was created
 	pmtu="$(route_get_dst_pmtu_from_exception "${ns_a}" ${dst})"
@@ -767,7 +765,7 @@ 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 2 -s $((${ll_mtu} + 500)) ${dst} > /dev/null
+	${ns_a} ${ping} -q -M want -i 0.1 -w 1 -s $((${ll_mtu} + 500)) ${dst} > /dev/null
 
 	# Check that exception was created
 	pmtu="$(route_get_dst_pmtu_from_exception "${ns_a}" ${dst})"
@@ -825,13 +823,13 @@ 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 2 -s ${ping_payload} ${tunnel4_b_addr} > /dev/null
+	${ns_a} ping -q -M want -i 0.1 -w 1 -s ${ping_payload} ${tunnel4_b_addr} > /dev/null
 	pmtu="$(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 2 -s $((ping_payload + 1)) ${tunnel4_b_addr} > /dev/null
+	${ns_a} ping -q -M want -i 0.1 -w 1 -s $((ping_payload + 1)) ${tunnel4_b_addr} > /dev/null
 	pmtu="$(route_get_dst_pmtu_from_exception "${ns_a}" ${tunnel4_b_addr})"
 	check_pmtu_value "${esp_payload_rfc4106}" "${pmtu}" "exceeding PMTU (IP payload length $((esp_payload_rfc4106 + 1)))"
 }
@@ -847,7 +845,7 @@ test_pmtu_vti6_exception() {
 	mtu "${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 2 -s 60000 ${tunnel6_b_addr} > /dev/null
+	${ns_a} ${ping6} -q -i 0.1 -w 1 -s 60000 ${tunnel6_b_addr} > /dev/null
 
 	# Check that exception was created
 	pmtu="$(route_get_dst_pmtu_from_exception "${ns_a}" ${tunnel6_b_addr})"
-- 
2.20.1

[PATCH net v2 2/2] selftests: pmtu: add explicit tests for PMTU exceptions cleanup

[Paolo Abeni]

Add a couple of new tests, explicitly checking that the kernel
timely releases PMTU exceptions on related device removal.
This is mostly a regression test vs the issue fixed by
commit f5b51fe804ec ("ipv6: route: purge exception on removal")

Only 2 new test cases have been added, instead of extending all
the existing ones, because the reproducer requires executing
several commands and would slow down too much the tests otherwise.

v1 -> v2:
 - several script cleanups, as suggested by Stefano

Signed-off-by: Paolo Abeni <pabeni@redhat.com>
---
 tools/testing/selftests/net/pmtu.sh | 67 ++++++++++++++++++++++++++++-
 1 file changed, 66 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/net/pmtu.sh b/tools/testing/selftests/net/pmtu.sh
index 89aec2fdf4fa..be0491c3acad 100755
--- a/tools/testing/selftests/net/pmtu.sh
+++ b/tools/testing/selftests/net/pmtu.sh
@@ -103,6 +103,15 @@
 #	and check that configured MTU is used on link creation and changes, and
 #	that MTU is properly calculated instead when MTU is not configured from
 #	userspace
+#
+# - pmtu_ipv4_exception_cleanup
+#	Similar to pmtu_ipv4_vxlan4_exception, but explicitly generate PMTU
+#	exceptions on multiple CPUs and check that the veth device tear-down
+# 	happens in a timely manner
+#
+# - pmtu_ipv6_exception_cleanup
+#	Same as above, but use IPv6 transport from A to B
+
 
 # Kselftest framework requirement - SKIP code is 4.
 ksft_skip=4
@@ -135,7 +144,9 @@ tests="
 	pmtu_vti6_default_mtu		vti6: default MTU assignment
 	pmtu_vti4_link_add_mtu		vti4: MTU setting on link creation
 	pmtu_vti6_link_add_mtu		vti6: MTU setting on link creation
-	pmtu_vti6_link_change_mtu	vti6: MTU changes on link changes"
+	pmtu_vti6_link_change_mtu	vti6: MTU changes on link changes
+	pmtu_ipv4_exception_cleanup	ipv4: cleanup of cached exceptions
+	pmtu_ipv6_exception_cleanup	ipv6: cleanup of cached exceptions"
 
 NS_A="ns-$(mktemp -u XXXXXX)"
 NS_B="ns-$(mktemp -u XXXXXX)"
@@ -1006,6 +1017,60 @@ test_pmtu_vti6_link_change_mtu() {
 	return ${fail}
 }
 
+chk_command() {
+	cmd=${1}
+
+	if ! which ${cmd} > /dev/null 2>&1; then
+		err "  missing required command: '${cmd}'"
+		return 1
+	fi
+	return 0
+}
+
+test_cleanup_vxlanX_exception() {
+	outer="${1}"
+	encap="vxlan"
+	ll_mtu=4000
+
+	chk_command taskset || return 2
+	chk_command timeout || return 2
+	cpu_list=$(grep -m 2 processor /proc/cpuinfo | cut -d ' ' -f 2)
+
+	setup namespaces routing ${encap}${outer} || return 2
+	trace "${ns_a}" ${encap}_a   "${ns_b}"  ${encap}_b \
+	      "${ns_a}" veth_A-R1    "${ns_r1}" veth_R1-A \
+	      "${ns_b}" veth_B-R1    "${ns_r1}" veth_R1-B
+
+	# Create route exception by exceeding link layer MTU
+	mtu "${ns_a}"  veth_A-R1 $((${ll_mtu} + 1000))
+	mtu "${ns_r1}" veth_R1-A $((${ll_mtu} + 1000))
+	mtu "${ns_b}"  veth_B-R1 ${ll_mtu}
+	mtu "${ns_r1}" veth_R1-B ${ll_mtu}
+
+	mtu "${ns_a}" ${encap}_a $((${ll_mtu} + 1000))
+	mtu "${ns_b}" ${encap}_b $((${ll_mtu} + 1000))
+
+	# 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
+	done
+
+	if ! timeout 1 ${ns_a} ip link del dev veth_A-R1; then
+		err "  can't delete veth device in a timely manner, PMTU dst likely leaked"
+		return 1
+	fi
+	return 0
+}
+
+test_pmtu_ipv6_exception_cleanup() {
+	test_cleanup_vxlanX_exception 6 vxlan
+}
+
+test_pmtu_ipv4_exception_cleanup() {
+	test_cleanup_vxlanX_exception 4 vxlan
+}
+
 usage() {
 	echo
 	echo "$0 [OPTIONS] [TEST]..."
-- 
2.20.1

Re: [PATCH net v2 2/2] selftests: pmtu: add explicit tests for PMTU exceptions cleanup

[Stefano Brivio]

Just three minor details, feel free to ignore:

On Mon, 25 Feb 2019 12:13:46 +0100
Paolo Abeni <pabeni@redhat.com> wrote:

> @@ -1006,6 +1017,60 @@ test_pmtu_vti6_link_change_mtu() {
>  	return ${fail}
>  }
>  
> +chk_command() {

All the other functions checking something are called 'check_*'.

> +	cmd=${1}
> +
> +	if ! which ${cmd} > /dev/null 2>&1; then
> +		err "  missing required command: '${cmd}'"
> +		return 1
> +	fi
> +	return 0
> +}
> +
> +test_cleanup_vxlanX_exception() {
> +	outer="${1}"
> +	encap="vxlan"
> +	ll_mtu=4000
> +
> +	chk_command taskset || return 2
> +	chk_command timeout || return 2
> +	cpu_list=$(grep -m 2 processor /proc/cpuinfo | cut -d ' ' -f 2)
> +
> +	setup namespaces routing ${encap}${outer} || return 2
> +	trace "${ns_a}" ${encap}_a   "${ns_b}"  ${encap}_b \
> +	      "${ns_a}" veth_A-R1    "${ns_r1}" veth_R1-A \
> +	      "${ns_b}" veth_B-R1    "${ns_r1}" veth_R1-B
> +
> +	# Create route exception by exceeding link layer MTU
> +	mtu "${ns_a}"  veth_A-R1 $((${ll_mtu} + 1000))
> +	mtu "${ns_r1}" veth_R1-A $((${ll_mtu} + 1000))
> +	mtu "${ns_b}"  veth_B-R1 ${ll_mtu}
> +	mtu "${ns_r1}" veth_R1-B ${ll_mtu}
> +
> +	mtu "${ns_a}" ${encap}_a $((${ll_mtu} + 1000))
> +	mtu "${ns_b}" ${encap}_b $((${ll_mtu} + 1000))
> +
> +	# 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
> +	done
> +
> +	if ! timeout 1 ${ns_a} ip link del dev veth_A-R1; then
> +		err "  can't delete veth device in a timely manner, PMTU dst likely leaked"
> +		return 1
> +	fi
> +	return 0

No need for explicit return 0.

> +}
> +
> +test_pmtu_ipv6_exception_cleanup() {
> +	test_cleanup_vxlanX_exception 6 vxlan
> +}
> +
> +test_pmtu_ipv4_exception_cleanup() {
> +	test_cleanup_vxlanX_exception 4 vxlan

This function now takes just one argument.

-- 
Stefano

Re: [PATCH net v2 2/2] selftests: pmtu: add explicit tests for PMTU exceptions cleanup

[Sabrina Dubroca]

2019-02-25, 12:13:46 +0100, Paolo Abeni wrote:
> +	if ! timeout 1 ${ns_a} ip link del dev veth_A-R1; then

That doesn't work. "ip link del" is stuck in a way that timeout can't
terminate it, so this is still going to hang. Did you actually test
this? :/

> +		err "  can't delete veth device in a timely manner, PMTU dst likely leaked"
> +		return 1
> +	fi
> +	return 0
> +}

-- 
Sabrina

Re: [PATCH net v2 2/2] selftests: pmtu: add explicit tests for PMTU exceptions cleanup

[Stefano Brivio]

On Mon, 25 Feb 2019 13:33:30 +0100
Sabrina Dubroca <sd@queasysnail.net> wrote:

> 2019-02-25, 12:13:46 +0100, Paolo Abeni wrote:
> > +	if ! timeout 1 ${ns_a} ip link del dev veth_A-R1; then  
> 
> That doesn't work. "ip link del" is stuck in a way that timeout can't
> terminate it, so this is still going to hang. Did you actually test
> this? :/

Indeed, upon actual testing, this hangs and the error is not reported.

> > +		err "  can't delete veth device in a timely
> > manner, PMTU dst likely leaked"
> > +		return 1
> > +	fi
> > +	return 0
> > +}  

You can use a subshell here, something like:

	${ns_a} ip link del dev veth_A-R1 &
	iplink_pid=$!
	sleep 1
	if [ "$(cat /proc/${iplink_pid}/cmdline 2>/dev/null | tr -d '\0')" = "iplinkdeldevveth_A-R1" ]; then
		err "  can't delete veth device in a timely manner, PMTU dst likely leaked"
		return 1
	fi
}

and now that I tried to run as a single test and couldn't find it, I
think it would also be worth it to rename the tests to something more
sensible.

Right now you have test_pmtu_ipv6_exception_cleanup() calling
test_cleanup_...(), I think it's confusing. Just call the test
test_cleanup_ipv6_exception(), it doesn't have so much to do with PMTU
anyway.

-- 
Stefano