Re: [PATCH net-next v4 02/12] udp: gso: Simplify handling length in GSO_PARTIAL

["Alice Mikityanska" <alice.kernel@fastmail.im>]

On Wed, May 13, 2026, at 09:53, Gal Pressman wrote:
> Hi Alice,
>
> On 12/05/2026 19:56, Alice Mikityanska wrote:
>> From: Alice Mikityanska <alice@isovalent.com>
>> 
>> Taking further the idea of commit b10b446ce7ad ("udp: gso: Use single
>> MSS length in UDP header for GSO_PARTIAL"), simplify the implementation
>> and fix the checksum (apparently ignored by hardware anyway).
>> 
>> The mentioned commit started using msslen for uh->len, but still uses
>> newlen to adjust uh->check. If the formula for check is fixed, newlen is
>> assigned but never used before the loop, and newlen is overwritten after
>> the loop. This makes msslen not really necessary, as we can reuse
>> newlen, if we don't adjust mss before. The adjustment of mss can be
>> simply dropped, because mss is not used anywhere else below.
>> 
>> This brings us back to one variable, drops an unneeded arithmetic for
>> mss, and fixes the UDP checksum.
>> 
>> Signed-off-by: Alice Mikityanska <alice@isovalent.com>
>> Cc: Gal Pressman <gal@nvidia.com>
>> Reviewed-by: Willem de Bruijn <willemb@google.com>
>
> Heads up, this is going to conflict with this fix:
> https://lore.kernel.org/netdev/20260513074349.2152146-1-gal@nvidia.com/

Thanks for the heads up! When I submitted mine, your patch wasn't on the
list yet, so it's rather the other way around :). Anyway, let's combine
our efforts, since we are fixing different aspects of the same area of
code. I commented on your patch and suggested to base it on top of mine
to avoid creating a new bug with the checksum. If my series doesn't get
merged in this iteration, feel free to cherry-pick this commit, it's
pretty much independent.