Messages in this thread | | | Date | Mon, 2 Oct 2023 19:11:46 +0200 | From | Florian Westphal <> | Subject | Re: [PATCH net] ipv6: avoid atomic fragment on GSO packets |
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Yan Zhai <yan@cloudflare.com> wrote: > On Sat, Sep 30, 2023 at 6:09 AM Florian Westphal <fw@strlen.de> wrote: > > > > This helper is also called for skbs where IP6CB(skb)->frag_max_size > > exceeds the MTU, so this check looks wrong to me. > > > > Same remark for dst_allfrag() check in __ip6_finish_output(), > > after this patch, it would be ignored. > > > Thanks for covering my carelessness. I was just considering the GSO > case so frag_max_size was overlooked. dst_allfrag is indeed a case > based on the code logic. But just out of curiosity, do we still see > any use of this feature? From commit messages it is set when PMTU > values signals smaller than min IPv6 MTU. But such PMTU values are > just dropped in __ip6_rt_update_pmtu now. Iproute2 code also does not > provide this route feature anymore. So it might be actually a dead > check?
I don't think iproute2 ever exposed it, I think we can axe dst_allfrag().
> > I think you should consider to first refactor __ip6_finish_output to make > > the existing checks more readable (e.g. handle gso vs. non-gso in separate > > branches) and then add the check to last seg in > > ip6_finish_output_gso_slowpath_drop(). > > > Agree with refactoring to mirror what IPv4 code is doing. It might not > hurt if we check every segments in this case, since it is already the > slowpath and it will make code more compact.
No objections from my side.
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