Commit 2759647247 ("ipv6: fix ECMP route replacement") introduced a
loop that removes all siblings of an ECMP route that is being
replaced. However, this loop doesn't stop when it has replaced
siblings, and keeps removing other routes with a higher metric.
We also end up triggering the WARN_ON after the loop, because after
this nsiblings < 0.
Instead, stop the loop when we have taken care of all routes with the
same metric as the route being replaced.
Reproducer:
===========
#!/bin/sh
ip netns add ns1
ip netns add ns2
ip -net ns1 link set lo up
for x in 0 1 2 ; do
ip link add veth$x netns ns2 type veth peer name eth$x netns ns1
ip -net ns1 link set eth$x up
ip -net ns2 link set veth$x up
done
ip -net ns1 -6 r a 2000::/64 nexthop via fe80::0 dev eth0 \
nexthop via fe80::1 dev eth1 nexthop via fe80::2 dev eth2
ip -net ns1 -6 r a 2000::/64 via fe80::42 dev eth0 metric 256
ip -net ns1 -6 r a 2000::/64 via fe80::43 dev eth0 metric 2048
echo "before replace, 3 routes"
ip -net ns1 -6 r | grep -v '^fe80\|^ff00'
echo
ip -net ns1 -6 r c 2000::/64 nexthop via fe80::4 dev eth0 \
nexthop via fe80::5 dev eth1 nexthop via fe80::6 dev eth2
echo "after replace, only 2 routes, metric 2048 is gone"
ip -net ns1 -6 r | grep -v '^fe80\|^ff00'
Fixes: 2759647247 ("ipv6: fix ECMP route replacement")
Signed-off-by: Sabrina Dubroca <sd@queasysnail.net>
Acked-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Reviewed-by: Xin Long <lucien.xin@gmail.com>
Reviewed-by: Michal Kubecek <mkubecek@suse.cz>
Signed-off-by: David S. Miller <davem@davemloft.net>
67e194007b