We could end up expiring a route which is part of an ecmp route set. Doing
so would invalidate the rt->rt6i_nsiblings calculations and could provoke
the following panic:
Cc: Nicolas Dichtel <nicolas.dichtel@6wind.com> Cc: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org> Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org> Signed-off-by: David S. Miller <davem@davemloft.net>