we are actually editing table, which means editing rules,
thus we need writer access to 'em.
Fix this by offloading the update of table to the same taskqueue,
we already use for flushing. Since taskqueues major task is now
overloading, and flushing is optional, do mechanical rename
s/flush/overload/ in the code related to the taskqueue.
Since overloading tasks do unsafe referencing of rules, provide
a bandaid in pf_purge_unlinked_rules(). If the latter sees any
queued tasks, then it skips purging for this run.
In table code:
- Assert any lock in pfr_lookup_addr().
- Assert writer lock in pfr_route_kentry().
29bdd62c85