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    mpls: Do not decrement alive counter for unregister events · 79099aab
    David Ahern 提交于
    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>
    79099aab
af_mpls.c 47.0 KB