On Tue, Sep 02, 2014 at 11:59:22AM +0100, Patrick McHardy wrote: > On Tue, Sep 02, 2014 at 12:38:56PM +0200, Pablo Neira Ayuso wrote: > > On Tue, Sep 02, 2014 at 11:14:41AM +0100, Patrick McHardy wrote: > > > On Tue, Sep 02, 2014 at 11:38:39AM +0200, Pablo Neira Ayuso wrote: > > > > The sets are released from the rcu callback, after the rule is removed > > > > from the chain list, which implies that nfnetlink cannot update the > > > > hashes (thus, no resizing may occur) and no packets are walking on the > > > > set anymore. > > > > > > Unrelated to your patch, but to the RCU destruction: how does that make > > > sure that nfnetlink notifications are received in the proper order? > > > I mean, theoretically a new set with the same name could exist at that > > > time. The same problem exists for all objects that have user defined > > > identifiers or refer to them. > > > > All the events (with the exception of anonymous sets) are sent in > > order from the commit path, so they are delivered in order. > > Sure, I was talking about independant additions: > > - delete set X > - RCU callback delayed > - add set X, notify > - RCU callback executes, notifies for delete set X Right, that's indeed a problem for bound-to-rule anonymous sets. > Same thing applies to all other objects that don't have a unique identifier > chosen by the kernel. All other objects are always notified in order from the commit path, so they seem fine to me. > > The anonymous sets are problematic, we need to notify this from the > > commit path too to ensure the right ordering. I was trying to avoid > > some specific notify() interface in expr->ops but it seems we need it > > for nft_lookup.c. > > > > Can you think of a better solution? > > No, unless we can come up with a way that's synchronous. I would really like not to go back to the two nearly consecutive synchronize_rcu() calls, it's slow. I've been thinking on replacing the current check in the packet path by static keys, but I didn't manage to find the way yet. -- 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
