Currently netdevsim relies on RTNL to maintain exclusivity in accessing the nexthop hash table. However, bucket notification may be called without RTNL having been held. Instead, introduce a custom lock to guard the table. Signed-off-by: Petr Machata <petrm@nvidia.com> Reviewed-by: Ido Schimmel <idosch@nvidia.com> Signed-off-by: David S. Miller <davem@davemloft.net>