Any ideas about how to fix the core issue of tb->fast* being effectively invalid?
ie. currently any reader of tb->fastreuse(port) which isn't simply testing for it being >= 0 is basically a bug (-1 is the empty tb case, so that AFAICT keeps on working). For example sk_reuseport_match(tb, sk) can both fail to match when it should, and can match when it shouldn't... (at a quick glance, all the readers, and thus bugs are constrained to the inet_csk_get_port() function) Do we just delete that entire 'tb->fast*' optimization? It would certainly make the code much simpler... Do we put special case per-family/protocol code (ie. presumably another indirect call) to fix up tb->fast in the setsockopt(SOREUSEADDR/PORT) codepath? Something else? (btw. I'm not certain if both 0->1 and 1->0 transitions on a bound socket are equally buggy, I think one is more dangerous then the other)
