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Thu, 06 Nov 2025 03:26:31 -0800 (PST) Received: from [192.168.88.32] ([212.105.155.83]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-429eb49a079sm4564491f8f.32.2025.11.06.03.26.29 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 06 Nov 2025 03:26:30 -0800 (PST) Message-ID: <1c79daaf-c092-4c49-a715-52aeb9688b48@redhat.com> Date: Thu, 6 Nov 2025 12:26:28 +0100 Precedence: bulk X-Mailing-List: linux-doc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v5 net-next 03/14] net: update commnets for SKB_GSO_TCP_ECN and SKB_GSO_TCP_ACCECN From: Paolo Abeni To: chia-yu.chang@nokia-bell-labs.com, edumazet@google.com, parav@nvidia.com, linux-doc@vger.kernel.org, corbet@lwn.net, horms@kernel.org, dsahern@kernel.org, kuniyu@google.com, bpf@vger.kernel.org, netdev@vger.kernel.org, dave.taht@gmail.com, jhs@mojatatu.com, kuba@kernel.org, stephen@networkplumber.org, xiyou.wangcong@gmail.com, jiri@resnulli.us, davem@davemloft.net, andrew+netdev@lunn.ch, donald.hunter@gmail.com, ast@fiberby.net, liuhangbin@gmail.com, shuah@kernel.org, linux-kselftest@vger.kernel.org, ij@kernel.org, ncardwell@google.com, koen.de_schepper@nokia-bell-labs.com, g.white@cablelabs.com, ingemar.s.johansson@ericsson.com, mirja.kuehlewind@ericsson.com, cheshire@apple.com, rs.ietf@gmx.at, Jason_Livingood@comcast.com, vidhi_goel@apple.com References: <20251030143435.13003-1-chia-yu.chang@nokia-bell-labs.com> <20251030143435.13003-4-chia-yu.chang@nokia-bell-labs.com> Content-Language: en-US In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit On 11/6/25 12:06 PM, Paolo Abeni wrote: > On 10/30/25 3:34 PM, chia-yu.chang@nokia-bell-labs.com wrote: >> From: Chia-Yu Chang >> >> No functional changes. >> >> Co-developed-by: Ilpo Järvinen >> Signed-off-by: Ilpo Järvinen >> Signed-off-by: Chia-Yu Chang >> --- >> include/linux/skbuff.h | 13 ++++++++++++- >> 1 file changed, 12 insertions(+), 1 deletion(-) >> >> diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h >> index a7cc3d1f4fd1..74d6a209e203 100644 >> --- a/include/linux/skbuff.h >> +++ b/include/linux/skbuff.h >> @@ -671,7 +671,12 @@ enum { >> /* This indicates the skb is from an untrusted source. */ >> SKB_GSO_DODGY = 1 << 1, >> >> - /* This indicates the tcp segment has CWR set. */ >> + /* For Tx, this indicates the first TCP segment has CWR set, and any >> + * subsequent segment in the same skb has CWR cleared. This cannot be >> + * used on Rx, because the connection to which the segment belongs is >> + * not tracked to use RFC3168 or Accurate ECN, and using RFC3168 ECN >> + * offload may corrupt AccECN signal of AccECN segments. >> + */ > > The intended difference between RX and TX sounds bad to me; I think it > conflicts with the basic GRO design goal of making aggregated and > re-segmented traffic indistinguishable from the original stream. Also > what about forwarded packet? Uhm... I missed completely the point that SKB_GSO_TCP_ECN is TX path only, i.e. GRO never produces aggregated SKB_GSO_TCP_ECN packets. Except virtio_net uses it in the RX path ( virtio_net_hdr_to_skb ). Please clarify the statement accordingly. /P