Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752314AbeACUNr (ORCPT + 1 other); Wed, 3 Jan 2018 15:13:47 -0500 Received: from mail.linuxfoundation.org ([140.211.169.12]:33620 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752292AbeACUNo (ORCPT ); Wed, 3 Jan 2018 15:13:44 -0500 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Neal Cardwell , Yuchung Cheng , Soheil Hassas Yeganeh , "David S. Miller" Subject: [PATCH 4.9 02/39] tcp_bbr: reset long-term bandwidth sampling on loss recovery undo Date: Wed, 3 Jan 2018 21:11:16 +0100 Message-Id: <20180103195104.163956717@linuxfoundation.org> X-Mailer: git-send-email 2.15.1 In-Reply-To: <20180103195104.066528044@linuxfoundation.org> References: <20180103195104.066528044@linuxfoundation.org> User-Agent: quilt/0.65 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Return-Path: 4.9-stable review patch. If anyone has any objections, please let me know. ------------------ From: Neal Cardwell commit 600647d467c6d04b3954b41a6ee1795b5ae00550 upstream. Fix BBR so that upon notification of a loss recovery undo BBR resets long-term bandwidth sampling. Under high reordering, reordering events can be interpreted as loss. If the reordering and spurious loss estimates are high enough, this can cause BBR to spuriously estimate that we are seeing loss rates high enough to trigger long-term bandwidth estimation. To avoid that problem, this commit resets long-term bandwidth sampling on loss recovery undo events. Signed-off-by: Neal Cardwell Reviewed-by: Yuchung Cheng Acked-by: Soheil Hassas Yeganeh Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/ipv4/tcp_bbr.c | 1 + 1 file changed, 1 insertion(+) --- a/net/ipv4/tcp_bbr.c +++ b/net/ipv4/tcp_bbr.c @@ -847,6 +847,7 @@ static u32 bbr_undo_cwnd(struct sock *sk bbr->full_bw = 0; /* spurious slow-down; reset full pipe detection */ bbr->full_bw_cnt = 0; + bbr_reset_lt_bw_sampling(sk); return tcp_sk(sk)->snd_cwnd; }