mpls: Do not decrement alive counter for unregister events
Multipath routes can be rendered usesless when a device in one of the paths is deleted. For example: $ ip -f mpls ro ls 100 nexthop as to 200 via inet 172.16.2.2 dev virt12 nexthop as to 300 via inet 172.16.3.2 dev br0 101 nexthop as to 201 via inet6 2000:2::2 dev virt12 nexthop as to 301 via inet6 2000:3::2 dev br0 $ ip li del br0 When br0 is deleted the other hop is not considered in mpls_select_multipath because of the alive check -- rt_nhn_alive is 0. rt_nhn_alive is decremented once in mpls_ifdown when the device is taken down (NETDEV_DOWN) and again when it is deleted (NETDEV_UNREGISTER). For a 2 hop route, deleting one device drops the alive count to 0. Since devices are taken down before unregistering, the decrement on NETDEV_UNREGISTER is redundant. Fixes: c89359a4 ("mpls: support for dead routes") Signed-off-by: NDavid Ahern <dsa@cumulusnetworks.com> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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