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([2a0d:3344:2712:7e10:4d59:d956:544f:d65c]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-45634f4c546sm15030425e9.7.2025.07.17.01.24.11 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 17 Jul 2025 01:24:12 -0700 (PDT) Message-ID: <9c67190f-62c2-4498-937d-5213de1a3fe0@redhat.com> Date: Thu, 17 Jul 2025 10:24:11 +0200 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH net-next] tcp: correct the skip logic in tcp_sacktag_skip() To: Xin Guo , ncardwell@google.com, Kuniyuki Iwashima Cc: netdev@vger.kernel.org, edumazet@google.com, davem@davemloft.net, dsahern@kernel.org, kuba@kernel.org References: <20250713152253.110107-1-guoxin0309@gmail.com> Content-Language: en-US From: Paolo Abeni In-Reply-To: <20250713152253.110107-1-guoxin0309@gmail.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 7/13/25 5:22 PM, Xin Guo wrote: > tcp_sacktag_skip() directly return the input skb only > if TCP_SKB_CB(skb)->seq>skip_to_seq, > this is not right, and the logic should be > TCP_SKB_CB(skb)->seq>=skip_to_seq, Adding Kuniyuki I'm not sure this statement is actually true. A more clear (and slightly more descriptive) commit message could help better understanding the issue. What is the bad behaviour you are observing? Ideally a packetdrill test case to demonstrate it would help > for example > if start_seq is equal to tcp_highest_sack_seq() , > the start_seq is equal to seq of skb which is from > tcp_highest_sack(). > and on the other side ,when > tcp_highest_sack_seq() < start_seq in > tcp_sacktag_write_queue(), > the skb is from tcp_highest_sack() will be ignored > in tcp_sacktag_skip(), so clean the logic also. > > Fixes: 75c119afe14f ("tcp: implement rb-tree based retransmit queue") At very least the fixes tag looks wrong, because AFAICS such change did not modify the behaviour tcp_sacktag_skip. > Signed-off-by: Xin Guo Thanks, Paolo