Re: TC bpf_csum_diff problems post-5.6 kernel

Thanks for the context!

I write back to the packet directly (I chain all the checksum updates
through a series of bpf_csum_diff() calls and then write back the
ultimate value).

Since we have a mixed fleet right now, I'm guessing I'm going to need
multiple versions of the TC BPF .o binary, since it looks like
bpf_skb_net_shrink() EINVAL's on 5.6 with that
BPF_F_ADJ_ROOM_NO_CSUM_RESET flag.

A small price to pay! Again: many thanks for this; this group is really great.

On Tue, Nov 2, 2021 at 5:28 PM Daniel Borkmann <[email protected]> wrote:
> For the update, did you use bpf_csum_update() helper or directly writing into
> the pkt?

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Thomas H. Ptacek