Every flow_offload entry is added into the table twice. Because of this,
rhashtable_free_and_destroy can't be used, since it would call kfree for
each flow_offload object twice.
This patch cleans up the flowtable via nf_flow_table_iterate() to
schedule removal of entries by setting on the dying bit, then there is
an explicitly invocation of the garbage collector to release resources.
Based on patch from Felix Fietkau.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
b408c5b04f