From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5823BC433EF for ; Sat, 19 Mar 2022 10:05:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242627AbiCSKGT (ORCPT ); Sat, 19 Mar 2022 06:06:19 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39738 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235071AbiCSKGS (ORCPT ); Sat, 19 Mar 2022 06:06:18 -0400 Received: from Chamillionaire.breakpoint.cc (Chamillionaire.breakpoint.cc [IPv6:2a0a:51c0:0:12e:520::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 367982CD832; Sat, 19 Mar 2022 03:04:56 -0700 (PDT) Received: from fw by Chamillionaire.breakpoint.cc with local (Exim 4.92) (envelope-from ) id 1nVVwx-0003do-2B; Sat, 19 Mar 2022 11:04:43 +0100 Date: Sat, 19 Mar 2022 11:04:43 +0100 From: Florian Westphal To: zhouzhouyi@gmail.com Cc: edumazet@google.com, davem@davemloft.net, yoshfuji@linux-ipv6.org, dsahern@kernel.org, kuba@kernel.org, pabeni@redhat.com, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Wei Xu Subject: Re: [PATCH] net:ipv4: send an ack when seg.ack > snd.nxt Message-ID: <20220319100443.GA13956@breakpoint.cc> References: <20220319090142.137998-1-zhouzhouyi@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220319090142.137998-1-zhouzhouyi@gmail.com> User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org zhouzhouyi@gmail.com wrote: > - if (after(ack, tp->snd_nxt)) > + if (after(ack, tp->snd_nxt)) { > + tcp_send_ack(sk); > return -1; > + } If we really need to do this we need to if (!(flag & FLAG_NO_CHALLENGE_ACK)) tcp_send_challenge_ack(sk); ... else this might result in two acks? Whats the problem thats being fixed here?