On Fri, Jan 16, 2015 at 07:35:57PM +0000, Patrick McHardy wrote: > On 16.01, Thomas Graf wrote: > > On 01/16/15 at 06:36pm, Patrick McHardy wrote: > > > On 16.01, Thomas Graf wrote: > > > > On 01/16/15 at 04:43pm, David Laight wrote: > > > > > The walker is unlikely to see items that get inserted early in the hash > > > > > table even without a resize. > > > > > > > > I don't follow, you have to explain this statement. > > > > > > > > Walkers which don't want to see duplicates or miss entries should > > > > just take the mutex. > > > > > > Well, we do have a problem with interrupted dumps. As you know once > > > the netlink message buffer is full, we return to userspace and > > > continue dumping during the next read. Expanding obviously changes > > > the order since we rehash from bucket N to N and 2N, so this will > > > indeed cause duplicate (doesn't matter) and missed entries. > > > > Right,but that's a Netlink dump issue and not specific to rhashtable. > > Well, rhashtable (or generally resizing) will make it a lot worse. > Usually we at worst miss entries which were added during the dump, > which is made up by the notifications. > > With resizing we might miss anything, its completely undeterministic. > > > Putting the sequence number check in place should be sufficient > > for sets, right? > > I don't see how. The problem is that the ordering of the hash changes > and it will skip different entries than those that have already been > dumped. I think the generation counter should catch up this sort of problems. The resizing is triggered by a new/deletion element, which bumps it once the transaction is handled. -- To unsubscribe from this list: send the line "unsubscribe netfilter-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
