[SRU][J/N][PATCH 0/2] ubuntu_kselftests_net/vrf_route_leaking.sh fails on 5.15 and 6.8 (LP: 1949484 / 1928890)

[Alessio Faina]

https://bugs.launchpad.net/bugs/1949484
https://bugs.launchpad.net/bugs/1928890


[ Impact ]

During the run of kernel selftests, the
ubuntu_kselftests_net/vrf_route_leaking.sh may fail from time to time
due to a timing issue.
When a new network namespace is created, it might take more that the
choosen 2 seconds delay, and it can appear as two types of failures:

TEST: Basic IPv6 connectivity [FAIL]

and possibly

TEST: Ping received ICMP Packet too big [FAIL]

The second failure is subordinated to the first one, as the network is
not ready yet to send/receive packets.

[ Fix ]

An upstream patch has been already merged to the linux kernel: 
* SHA d83a5806759278c4898cd7c2116432e5b08df1df from upstream

For noble this is a clean cherry-pick. 

For Jammy another set of patches was needed to import the "slowwait" function.
The original patch cleanly applies, but the commits a4022a332f437, 
25ae948b44788 and ea63ac1429256 were partially backported to add this
functionality.

[ Test Plan ]

The new vrf_route_leaking.sh script has been continuously run on a Noble
and a Jammy VMs for multiple hours: before the patch was applied the
test was failing every 3 to 5 minutes, afte rthe application of the
patch, there was no observable failure for more than 2 hours.

Basic test result

root at ubuntu-jammy:~/linux-5.15/tools/testing/selftests/net# ./vrf_route_leaking.sh 

###########################################################################
IPv4 (sym route): VRF ICMP ttl error route lookup ping
###########################################################################

TEST: Basic IPv4 connectivity                                       [ OK ]
TEST: Ping received ICMP ttl exceeded                               [ OK ]

###########################################################################
IPv4 (sym route): VRF ICMP error route lookup traceroute
###########################################################################

TEST: Basic IPv4 connectivity                                       [ OK ]
TEST: Traceroute reports a hop on r1                                [ OK ]

###########################################################################
IPv4 (sym route): VRF ICMP fragmentation error route lookup ping
###########################################################################

TEST: Basic IPv4 connectivity                                       [ OK ]
TEST: Ping received ICMP Frag needed                                [ OK ]

###########################################################################
IPv4 (asym route): VRF ICMP ttl error route lookup ping
###########################################################################

TEST: Basic IPv4 connectivity                                       [ OK ]
TEST: Ping received ICMP ttl exceeded                               [ OK ]

###########################################################################
IPv4 (asym route): VRF ICMP error route lookup traceroute
###########################################################################

TEST: Basic IPv4 connectivity                                       [ OK ]
TEST: Traceroute reports a hop on r1                                [ OK ]

###########################################################################
IPv6 (sym route): VRF ICMP ttl error route lookup ping
###########################################################################

TEST: Basic IPv6 connectivity                                       [ OK ]
TEST: Ping received ICMP Hop limit                                  [ OK ]

###########################################################################
IPv6 (sym route): VRF ICMP error route lookup traceroute
###########################################################################

TEST: Basic IPv6 connectivity                                       [ OK ]
TEST: Traceroute6 reports a hop on r1                               [ OK ]

###########################################################################
IPv6 (sym route): VRF ICMP fragmentation error route lookup ping
###########################################################################

TEST: Basic IPv6 connectivity                                       [ OK ]
TEST: Ping received ICMP Packet too big                             [ OK ]

###########################################################################
IPv6 (asym route): VRF ICMP ttl error route lookup ping
###########################################################################

TEST: Basic IPv6 connectivity                                       [ OK ]
TEST: Ping received ICMP Hop limit                                  [ OK ]

###########################################################################
IPv6 (asym route): VRF ICMP error route lookup traceroute
###########################################################################

TEST: Basic IPv6 connectivity                                       [ OK ]
TEST: Traceroute6 reports a hop on r1                               [ OK ]

Tests passed:  20
Tests failed:   0
root at ubuntu-jammy:~/linux-5.15/tools/testing/selftests/net# 

The test were conducted using the following script:

root at ubuntu-jammy:~/linux-5.15/tools/testing/selftests/net# cat continuous_vrf_test.sh
#!/bin/bash
i=0
SECONDS=0
cleanup() {
	echo ""
	echo $i
	duration=$SECONDS
	echo "$((duration / 60)) minutes and $((duration % 60)) seconds elapsed."
}

stats() {
	echo "+++++++++++++++++++++++++++++++++++++++++++++++++++"
	echo "+++++++++++++++++++++++++++++++++++++++++++++++++++"
	echo $i
	duration=$SECONDS
	echo "$((duration / 60)) minutes and $((duration % 60)) seconds elapsed."
	echo "+++++++++++++++++++++++++++++++++++++++++++++++++++"
	echo "+++++++++++++++++++++++++++++++++++++++++++++++++++"
}

trap cleanup INT
while [ true ];
do
	./vrf_route_leaking.sh
	if [ ! "$?" == "0" ];
	then
		stats
		break;
	fi
	((i++))
	stats
done

After 2 hours, there was no trace of errors on both Jammy and Noble VMs.


[ Regression potential ]

No regression can happen, as the patch is only applied to the selftest
scripts.


-- 
2.43.0