Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx> wrote: [ CC Andy, see below for ip_fragment api discussion ] > > Lets start untangling bridge, bridge netfilter, and the > > rest of the ip stack (esp. ip_fragment). > > > > This changes ip_fragment() so that bridge netfilter > > can pass in the required information as arguments instead > > of using skb->nf_bridge to pass some extra information to it. > > > > Another problem with br_netfilter and the way its plumbed to > > ip/ip6-tables (physdev match) is skb->nf_bridge. > > > > nf_bridge is kmalloced blob with some extra information, including > > the bridge in and outports (mainly for iptables' physdev match). > > It also has various state bits so we know what manipulations > > have been performed by bridge netfilter on the skb (e.g. > > ppp header stripping). > > > > nf_bridge also provides scratch space where br_netfilter saves > > (and later restores) various things, e.g. ipv4 address for > > dnat detection, mac address to fix up ip fragmented skbs, etc. > > > > But in almost all cases we can avoid using ->data completely. > > I think one of the goals of this patchset is to prepare the removal of > that nf_bridge pointer from sk_buff which sounds as a good idea to me. The 2nd (and last half) of the set folds nf_bridge_info into skbuff, at the end (where its not initialized at allocation time). The struct is a lot smaller by then (16 bytes on 64bit, 12 on 32bit) so we'd increase skbuff size only by 8. > Did you consider to implement this scratchpad area using a per-cpu > area? I mean, something similar to what we used to have in > ip_conntrack for events: > > http://www.cs.fsu.edu/~baker/devices/lxr/http/source/linux/net/netfilter/nf_conntrack_ecache.c?v=2.6.25#L65 > > Following that approach, I think we could avoid changing the > ip_fragment() interface. Yes, I had a patch that used a percpu area. BUT, please see conflicting patch: http://patchwork.ozlabs.org/patch/447939/ So if OVS needs such an interface I thought it makes no sense to work around current API using percpu data. Andy, it looks like I could either wait for your patches to hit net-next, or you could refactor your changes based on my ip_fragment changes; AFAICS the use cases are pretty much the same so both ovs and bridge netfilter could use one unified ip_fragment(). > My concern is that these changes are too > specific of br_netfilter, which is not a good reference client of it > given all its design problems. I agree that change just for br_netfilter sake sucks but please also keep in mind that right now we have 'extra signalling' into ip_frament via skb->nf_bridge pointer which I dislike even more. > I'm preparing a new net-next batch, I can quickly take these three if > you agree: > > 1/8 bridge: move mac header copying into br_netfilter > 2/8 netfilter: bridge: move nf_bridge_update_protocol to where its used > 4/8 netfilter: bridge: refactor conditional in br_nf_dev_queue_xmit Sure. I can then submit the entire series (i.e. part1 without these 3 plus part2). I have no further br netfilter changes after that. > Regarding 3/8, I think we can move that code to br_netfilter.c so we > reduce ifdef pollution a bit and keep as much of this monster code > fenced under that file. Please, see patch attached. Sure. > BTW, 6/8 I think needs some ifdef to make sure NF_CONNTRACK is in > placed. 7/8 needs NF_BRDIGE_MAX_MAC_HEADER_LENGTH which seems to have > a small typo in it, well these are dependent of 4/8 anyway. Seems you're right, I'll look at it, thanks Pablo! -- 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
