From patchwork Sat Nov 3 16:54:31 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yafang Shao X-Patchwork-Id: 992670 X-Patchwork-Delegate: davem@davemloft.net Return-Path: X-Original-To: patchwork-incoming-netdev@ozlabs.org Delivered-To: patchwork-incoming-netdev@ozlabs.org Authentication-Results: ozlabs.org; spf=none (mailfrom) smtp.mailfrom=vger.kernel.org (client-ip=209.132.180.67; helo=vger.kernel.org; envelope-from=netdev-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=gmail.com header.i=@gmail.com header.b="The2+Muq"; dkim-atps=neutral Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 42nQ6N30RZzB4gJ for ; Sun, 4 Nov 2018 03:55:08 +1100 (AEDT) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728530AbeKDCGo (ORCPT ); Sat, 3 Nov 2018 22:06:44 -0400 Received: from mail-pg1-f196.google.com ([209.85.215.196]:39357 "EHLO mail-pg1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727508AbeKDCGo (ORCPT ); Sat, 3 Nov 2018 22:06:44 -0400 Received: by mail-pg1-f196.google.com with SMTP id r9-v6so2324557pgv.6; Sat, 03 Nov 2018 09:54:55 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id; bh=PkU2TzgCLqIr6brsSG/jWvDFCvA3KRYUmoZUhlMH0nY=; b=The2+MuqJx67/zFxUG30pVGhvrhseGz1X0MjZDNk9+XikzlIb2RlN4HW28Vniqhay+ dItAvv/G59350Z4DXwGhZ1pLyNt9TlUT9zTmDPPrNcvRsJ2Sxsfjt8ipZNgoPfxViP4L eGPYhZuvmmMUwjGn1jK8N1A9bxApyuzpdS54kWqrnmOjfs4lcp5DekQ9wo4A3BYOPvM0 INwJvDDUFIibAZ6iGY5qsrc2OdrmQ43FdB1mc8TqJsYb/eTiv6mbGHlNmPv/MnWr9tfz +14YGZbhucZOBYEbUbKAivHPn4VuLjjeQqS7J5dsc8wauF5cOENhZEeVKN/vV0nmX/hi sT+g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id; bh=PkU2TzgCLqIr6brsSG/jWvDFCvA3KRYUmoZUhlMH0nY=; b=haWRkuXD+kWiT3hh9qCd1K/p3/h+hA0hJNCCWQHAgxfB9IP3qztfn6cHnx3w71WeZ1 HPA2y8Idkj4qHGt8V1Nf/C/TZF8vCL9Dw7YHhAz+2gdU/Qgf0DnceZ1cSzhn+3VgnHr6 JA6viDRg28NV03TFJufaF2Y27cfkX4T0tE0fVLSLmrjDPPnfnoP1DccjRR0BySHgzlwz Zw9fAuCGZcFl24GHVAt5zDxtUDE8pZVEKSQcRm7rOzZhAnLY2gV9hBJzJ9eI5LOJk5co y+MjoIYPzik6s6WfxJRLMQAy9KBqKIoL8w63+9wMmboREpKQibgW8lDZVTwJptrYe3iI JIDA== X-Gm-Message-State: AGRZ1gLP87bEfvLPBjWv39hZtzYLyjbLVNuw+HgpLqfX8SUdOQ+2uthv cf1Vjo0DfuIH16S/KEZPUXo= X-Google-Smtp-Source: AJdET5dL5aD8bcdojyHv8rv51SkLke4M/GtvTiF4SIR0bOqRcuyENva5pg/E3B+0httSn060G3iCLg== X-Received: by 2002:a65:5a05:: with SMTP id y5-v6mr14593134pgs.161.1541264095400; Sat, 03 Nov 2018 09:54:55 -0700 (PDT) Received: from localhost.localdomain ([203.100.54.194]) by smtp.gmail.com with ESMTPSA id r26-v6sm36006568pga.69.2018.11.03.09.54.53 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Sat, 03 Nov 2018 09:54:54 -0700 (PDT) From: Yafang Shao To: davem@davemloft.net, edumazet@google.com Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Yafang Shao Subject: [PATCH] tcp: do not update snd_una if it is same with ack_seq Date: Sun, 4 Nov 2018 00:54:31 +0800 Message-Id: <1541264071-9905-1-git-send-email-laoar.shao@gmail.com> X-Mailer: git-send-email 1.8.3.1 Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org In the slow path, TCP_SKB_SB(skb)->ack_seq may be same with tp->snd_una, and under this condition we don't need to update the snd_una. Furthermore, tcp_ack_update_window() is only called in slow path, so introducing this check won't affect the fast path processing. By the way, '&' is a little faster than '-', so I replaced after() with "flag & FLAG_SND_UNA_ADVANCED". Signed-off-by: Yafang Shao --- net/ipv4/tcp_input.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index 2868ef2..db5a6b7 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -3376,7 +3376,8 @@ static int tcp_ack_update_window(struct sock *sk, const struct sk_buff *skb, u32 } } - tcp_snd_una_update(tp, ack); + if (after(ack, tp->snd_una)) + tcp_snd_una_update(tp, ack); return flag; } @@ -3610,7 +3611,7 @@ static int tcp_ack(struct sock *sk, const struct sk_buff *skb, int flag) if (flag & FLAG_UPDATE_TS_RECENT) tcp_replace_ts_recent(tp, TCP_SKB_CB(skb)->seq); - if (!(flag & FLAG_SLOWPATH) && after(ack, prior_snd_una)) { + if (!(flag & FLAG_SLOWPATH) && flag & FLAG_SND_UNA_ADVANCED) { /* Window is constant, pure forward advance. * No more checks are required. * Note, we use the fact that SND.UNA>=SND.WL2.