• David Ahern's avatar
    net: ipv6: Delete host routes on an ifdown · 38bd10c4
    David Ahern authored
    It was a simple idea -- save IPv6 configured addresses on a link down
    so that IPv6 behaves similar to IPv4. As always the devil is in the
    details and the IPv6 stack as too many behavioral differences from IPv4
    making the simple idea more complicated than it needs to be.
    
    The current implementation for keeping IPv6 addresses can panic or spit
    out a warning in one of many paths:
    
    1. IPv6 route gets an IPv4 route as its 'next' which causes a panic in
       rt6_fill_node while handling a route dump request.
    
    2. rt->dst.obsolete is set to DST_OBSOLETE_DEAD hitting the WARN_ON in
       fib6_del
    
    3. Panic in fib6_purge_rt because rt6i_ref count is not 1.
    
    The root cause of all these is references related to the host route for
    an address that is retained.
    
    So, this patch deletes the host route every time the ifdown loop runs.
    Since the host route is deleted and will be re-generated an up there is
    no longer a need for the l3mdev fix up. On the 'admin up' side move
    addrconf_permanent_addr into the NETDEV_UP event handling so that it
    runs only once versus on UP and CHANGE events.
    
    All of the current panics and warnings appear to be related to
    addresses on the loopback device, but given the catastrophic nature when
    a bug is triggered this patch takes the conservative approach and evicts
    all host routes rather than trying to determine when it can be re-used
    and when it can not. That can be a later optimizaton if desired.
    Signed-off-by: default avatarDavid Ahern <dsa@cumulusnetworks.com>
    Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
    38bd10c4
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