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Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Willem de Bruijn , kernel-team@cloudflare.com Subject: Re: [PATCH net 0/2] Lift UDP_SEGMENT restriction for egress via device w/o csum offload In-Reply-To: <6677da5b3c52e_334d34294dd@willemb.c.googlers.com.notmuch> (Willem de Bruijn's message of "Sun, 23 Jun 2024 04:18:35 -0400") References: <20240622-linux-udpgso-v1-0-d2344157ab2a@cloudflare.com> <6677da5b3c52e_334d34294dd@willemb.c.googlers.com.notmuch> User-Agent: mu4e 1.12.4; emacs 29.1 Date: Mon, 24 Jun 2024 13:29:28 +0200 Message-ID: <87r0cmwpd3.fsf@cloudflare.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain On Sun, Jun 23, 2024 at 04:18 AM -04, Willem de Bruijn wrote: > Jakub Sitnicki wrote: >> This is a follow-up to an earlier question [1] if we can make UDP GSO work with >> any egress device, even those with no checksum offload capability. That's the >> default setup for TUN/TAP. >> >> I leave it to the maintainers to decide if it qualifies as a fix. We plan to >> backport it to our v6.6 either way, hence the submission to -net. >> >> [1] https://lore.kernel.org/netdev/87jzqsld6q.fsf@cloudflare.com/ > > Agreed with the change to allow UDP_SEGMENT to work regardless of > device capabilities. Thanks for the stamp. > In my opinion this is a new feature with sufficient risk of unintended > side effects to be net-next material. OK, I will resubmit for net-next. > Maybe worth recording in patch 1 the reason for the original check: > that UDP_SEGMENT with software checksumming in the GSO stack may be > a regression vs copy_and_checksum in the send syscall. Will expand the description.