On Mon, 27 Aug 2012, Jesper Dangaard Brouer wrote:
When loading "nf_conntrack_ipv6" I run into issues.
When sending a fragmented UDP packet. With these patches, the IPVS
stack will no longer see the fragmented packets, but instead see one
large SKB. This will trigger a MTU path check in e.g.
ip_vs_dr_xmit_v6() and an ICMPv6 too big packet is send back.
IPVS: ip_vs_dr_xmit_v6(): frag needed
Perhaps we could change/fix the MTU check in IPVS?
(This would also solve issues I've seen with TSO/GSO frames, hitting
this code path).
I guess this should use the same check as in IPv6 output, check
whether IP6CB(skb)->max_frag_size is != 0 and > MTU and only send
an ICMPv6 error in that case.
Hans have (already) proposed this solution:
if ((!skb->local_df && skb->len > mtu && !skb_is_gso(skb)) ||
(IP6CB(skb)->frag_max_size && IP6CB(skb)->frag_max_size > mtu)) {
And I have tested it works.
But I'm not sure about, if we really need the "!skb->local_df" check ?
Not necessarily, alternatively you could use:
if ((!IP6CB(skb)->frag_max_size &&
(skb->len > mtu && !skb_is_gso(skb)) ||
IP6CB(skb)->frag_max_size > mtu)
We just need to make sure that if frag_max_size is set that skb->len
is ignored. Either way is fine, but I'd suggest to keep it similar to
the variant used in IPv6.
Thus, we should extend you patchset with a patch, that also address the
MTU checks in IPVS.
Can you send over a patch for inclusion in the patchset? Besides this, its
ready for submission.
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