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[2a01:cb05:923c:9a00:5c:e1bc:b379:3264]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4aa7f41895fsm16607085e9.5.2026.10.28.14.40.54 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 28 Oct 2026 14:40:55 -0700 (PDT) Date: Wed, 28 Oct 2026 22:40:52 +0100 From: Guillaume Nault To: Neal Cardwell Cc: Neal Cardwell , Tom.D.Williams@morganstanley.com, davem@davemloft.net, edumazet@kernel.org, horms@kernel.org, kuba@kernel.org, kuniyu@google.com, netdev@vger.kernel.org, pabeni@redhat.com, ycheng@google.com Subject: Re: [PATCH net] tcp: Fix dup-ack detection on non-SACK bidirectional data transfer. Message-ID: References: <2ab9dc5f5b5e9f50d7a4aa02a6b6759fc86314c7.1792658454.git.gnault@redhat.com> <20261023161013.3079347-1-ncardwell.sw@gmail.com> X-Mailing-List: netdev@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Fri, Oct 23, 2026 at 01:04:48PM -0400, Neal Cardwell wrote: > > diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c > > index 99baf14afdfd..1feb370804b1 100644 > > --- a/net/ipv4/tcp_input.c > > +++ b/net/ipv4/tcp_input.c > > @@ -107,7 +107,8 @@ int sysctl_tcp_max_orphans __read_mostly = NR_FILE; > > #define FLAG_TS_PROGRESS 0x40000 /* Positive timestamp delta */ > > > > #define FLAG_ACKED (FLAG_DATA_ACKED|FLAG_SYN_ACKED) > > -#define FLAG_NOT_DUP (FLAG_DATA|FLAG_WIN_UPDATE|FLAG_ACKED) > > +#define FLAG_NOT_DUP (FLAG_DATA|FLAG_WIN_UPDATE|FLAG_ACKED|\ > > + FLAG_SND_UNA_ADVANCED) > > #define FLAG_CA_ALERT (FLAG_DATA_SACKED|FLAG_ECE|FLAG_DSACKING_ACK) > > #define FLAG_FORWARD_PROGRESS (FLAG_ACKED|FLAG_DATA_SACKED) > > > > @@ -3959,10 +3960,10 @@ static int tcp_ack_update_window(struct sock *sk, const struct sk_buff *skb, u32 > > nwin <<= tp->rx_opt.snd_wscale; > > > > if (tcp_may_update_window(tp, ack, ack_seq, nwin)) { > > - flag |= FLAG_WIN_UPDATE; > > tcp_update_wl(tp, ack_seq); > > > > if (tp->snd_wnd != nwin) { > > + flag |= FLAG_WIN_UPDATE; > > tp->snd_wnd = nwin; > > > > /* Note, it is the only place, where > > @@ -4354,7 +4355,6 @@ static int tcp_ack(struct sock *sk, const struct sk_buff *skb, int flag) > > */ > > tcp_update_wl(tp, ack_seq); > > tcp_snd_una_update(tp, ack); > > - flag |= FLAG_WIN_UPDATE; > > > > NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPHPACKS); > > } else { > > -- > > 2.47.3 > > This patch passes all of our internal tests, as well as the new > tools/testing/selftests/net/packetdrill/tcp_bidir_fast_retransmit_nosack.pkt > test that Guillaume Nault posted in this thread. > Thanks a lot for the tests. I wasn't sure if I should put your Tested-by tag to my v2. Feel free to add it :).