Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753873AbdHIRH2 (ORCPT ); Wed, 9 Aug 2017 13:07:28 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:39246 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753946AbdHIQyd (ORCPT ); Wed, 9 Aug 2017 12:54:33 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Eric Dumazet , Neal Cardwell , Yuchung Cheng , Soheil Hassas Yeganeh , "David S. Miller" Subject: [PATCH 4.12 062/106] tcp_bbr: remove sk_pacing_rate=0 transient during init Date: Wed, 9 Aug 2017 09:52:46 -0700 Message-Id: <20170809164525.295720290@linuxfoundation.org> X-Mailer: git-send-email 2.14.0 In-Reply-To: <20170809164515.714288642@linuxfoundation.org> References: <20170809164515.714288642@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 Content-Length: 1438 Lines: 40 4.12-stable review patch. If anyone has any objections, please let me know. ------------------ From: Neal Cardwell [ Upstream commit 1d3648eb5d1fe9ed3d095ed8fa19ad11ca4c8bc0 ] Fix a corner case noticed by Eric Dumazet, where BBR's setting sk->sk_pacing_rate to 0 during initialization could theoretically cause packets in the sending host to hang if there were packets "in flight" in the pacing infrastructure at the time the BBR congestion control state is initialized. This could occur if the pacing infrastructure happened to race with bbr_init() in a way such that the pacer read the 0 rather than the immediately following non-zero pacing rate. Fixes: 0f8782ea1497 ("tcp_bbr: add BBR congestion control") Reported-by: Eric Dumazet Signed-off-by: Neal Cardwell Signed-off-by: Yuchung Cheng Signed-off-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 deletion(-) --- a/net/ipv4/tcp_bbr.c +++ b/net/ipv4/tcp_bbr.c @@ -838,7 +838,6 @@ static void bbr_init(struct sock *sk) minmax_reset(&bbr->bw, bbr->rtt_cnt, 0); /* init max bw to 0 */ - sk->sk_pacing_rate = 0; /* force an update of sk_pacing_rate */ bbr_init_pacing_rate_from_rtt(sk); bbr->restore_cwnd = 0;