Re: [PATCH net-next v3 02/15] net: skbuff: add skb_checksum_full() that reports failure

[Josef Bacik <josef@xxxxxxxxxxxxxx>]

On Mon, Nov 02, 2026 at 06:44:46PM -0800, Mina Almasry wrote:
> Hmm, but do we really want this intermediate state where skb_checksum
> and skb_checksum_full exist? Why not fix it in one go rather than
> little by little?

I don't want to keep it, the wrappers go away once the last caller is
converted.  I just can't get there in one go.

After this series skb_checksum() still has 44 call sites in 28 files:
11 in netfilter and ipvs, 13 in ipv4 and ipv6, 13 in six drivers, 2 each
in mptcp, bpf and pktgen, and 1 in xfrm.  Changing the prototype means
converting all of them in the same patch, and that one patch would go
through netfilter, ipsec, mptcp, bpf and the drivers at once.

It isn't a mechanical change either.  Each caller has to do something
with the error, and 17 of the 44 are in functions that return void, for
example udp4_hwcsum(), ip_cmsg_recv_checksum(),
mptcp_update_data_checksum() and nft_payload_set_eval().  Those need
their own callers looked at first.

skb_crc32c() looks smaller with three callers left, but one of them is
sctp_compute_cksum(), which has 11 callers of its own in sctp,
netfilter, openvswitch and act_csum.  The other two are siw and
batman-adv.

So this series converts the core users, because patch 3 closes a hole
where a packet that couldn't be checksummed passes validation and I
didn't want that to wait for the rest.  After that it's one small series
per subsystem, and the last one removes the wrapper.

This is my plan for everything, in response to your cover letter. I've
got a 15 patch limit and a one series per net/net-next. I'm trying to
make this as easy as possible so that they can be spot checked and
merged quickly. I started with core and I'm slowly working my way out.
I'm purposely avoiding "change all the callers" style patches because
that's harder to review. This is slower but easier for everybody, at
least I think it's easier.

Thanks,
Josef