[PATCH net-next v2] selftests: net: add ipv6 RA route to ECMP merge test

[PATCH net-next v2] selftests: net: add ipv6 RA route to ECMP merge test

[Fernando Fernandez Mancera]

As commit bbf4a17ad9ff ("ipv6: Fix ECMP sibling count mismatch when
clearing RTF_ADDRCONF") pointed out, RA routes are not elegible for ECMP
merging.

Add a test scenario mixing RA and static routes with gateway to check
that they are not getting merged.

Signed-off-by: Fernando Fernandez Mancera <fmancera@suse.de>
---
v2: added CONFIG_IPV6_ROUTE_INFO to the config
---
 tools/testing/selftests/net/config       |  1 +
 tools/testing/selftests/net/fib_tests.sh | 17 +++++++++++++++++
 2 files changed, 18 insertions(+)

diff --git a/tools/testing/selftests/net/config b/tools/testing/selftests/net/config
index cd49b7dfe216..69e22bde0fdb 100644
--- a/tools/testing/selftests/net/config
+++ b/tools/testing/selftests/net/config
@@ -43,6 +43,7 @@ CONFIG_IPV6_ILA=m
 CONFIG_IPV6_IOAM6_LWTUNNEL=y
 CONFIG_IPV6_MROUTE=y
 CONFIG_IPV6_MULTIPLE_TABLES=y
+CONFIG_IPV6_ROUTE_INFO=y
 CONFIG_IPV6_RPL_LWTUNNEL=y
 CONFIG_IPV6_SEG6_LWTUNNEL=y
 CONFIG_IPV6_SIT=y
diff --git a/tools/testing/selftests/net/fib_tests.sh b/tools/testing/selftests/net/fib_tests.sh
index c5694cc4ddd2..1262ee1ea09b 100755
--- a/tools/testing/selftests/net/fib_tests.sh
+++ b/tools/testing/selftests/net/fib_tests.sh
@@ -1534,6 +1534,23 @@ fib6_ra_to_static()
 
 	log_test $ret 0 "ipv6 promote RA route to static"
 
+	# Prepare for RA route with gateway
+	$NS_EXEC sysctl -wq net.ipv6.conf.veth1.accept_ra_rt_info_max_plen=64
+
+	# Add initial route to cause ECMP merging
+	$IP -6 route add 2001:12::/64 via fe80::dead:beef dev veth1
+
+	$NS_EXEC ra6 -i veth2 -d 2001:10::1 -R 2001:12::/64#1#120
+
+	# Routes are not merged as RA routes are not elegible for ECMP
+	check_rt_num 2 "$($IP -6 route list | grep -c "2001:12::/64 via")"
+
+	$IP -6 route append 2001:12::/64 via fe80::dead:feeb dev veth1
+
+	check_rt_num 2 "$($IP -6 route list | grep -c "nexthop via")"
+
+	log_test "$ret" 0 "ipv6 RA route with nexthop do not merge into ECMP with static"
+
 	set +e
 
 	cleanup &> /dev/null
-- 
2.53.0

Re: [PATCH net-next v2] selftests: net: add ipv6 RA route to ECMP merge test

[Jakub Kicinski]

On Thu, 26 Feb 2026 13:02:37 +0100 Fernando Fernandez Mancera wrote:
> As commit bbf4a17ad9ff ("ipv6: Fix ECMP sibling count mismatch when
> clearing RTF_ADDRCONF") pointed out, RA routes are not elegible for ECMP
> merging.
> 
> Add a test scenario mixing RA and static routes with gateway to check
> that they are not getting merged.
> 
> Signed-off-by: Fernando Fernandez Mancera <fmancera@suse.de>
> ---
> v2: added CONFIG_IPV6_ROUTE_INFO to the config

Same thing:

# 96.88 [+0.01] sysctl: cannot stat /proc/sys/net/ipv6/conf/veth1/accept_ra_rt_info_max_plen: No such file or directory

Config:
https://netdev-ctrl.bots.linux.dev/logs/vmksft/net-dbg/results/535301/config
looks like you're missing a dependency (IPV6_ROUTER_PREF)

Please do try to build a kernel to make sure the config options stick,
before posting v3. More instructions FWIW
https://github.com/linux-netdev/nipa/wiki/How-to-run-netdev-selftests-CI-style
-- 
pw-bot: cr