Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753671AbbDZN7O (ORCPT ); Sun, 26 Apr 2015 09:59:14 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:40575 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752561AbbDZNr6 (ORCPT ); Sun, 26 Apr 2015 09:47:58 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Neal Cardwell , Yuchung Cheng , "David S. Miller" Subject: [PATCH 3.10 05/31] tcp: fix FRTO undo on cumulative ACK of SACKed range Date: Sun, 26 Apr 2015 15:46:25 +0200 Message-Id: <20150426134209.480209647@linuxfoundation.org> X-Mailer: git-send-email 2.3.6 In-Reply-To: <20150426134209.255099785@linuxfoundation.org> References: <20150426134209.255099785@linuxfoundation.org> User-Agent: quilt/0.64 MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1831 Lines: 53 3.10-stable review patch. If anyone has any objections, please let me know. ------------------ From: Neal Cardwell [ Upstream commit 666b805150efd62f05810ff0db08f44a2370c937 ] On processing cumulative ACKs, the FRTO code was not checking the SACKed bit, meaning that there could be a spurious FRTO undo on a cumulative ACK of a previously SACKed skb. The FRTO code should only consider a cumulative ACK to indicate that an original/unretransmitted skb is newly ACKed if the skb was not yet SACKed. The effect of the spurious FRTO undo would typically be to make the connection think that all previously-sent packets were in flight when they really weren't, leading to a stall and an RTO. Signed-off-by: Neal Cardwell Signed-off-by: Yuchung Cheng Fixes: e33099f96d99c ("tcp: implement RFC5682 F-RTO") Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/ipv4/tcp_input.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -3076,10 +3076,11 @@ static int tcp_clean_rtx_queue(struct so if (seq_rtt < 0) { seq_rtt = ca_seq_rtt; } - if (!(sacked & TCPCB_SACKED_ACKED)) + if (!(sacked & TCPCB_SACKED_ACKED)) { reord = min(pkts_acked, reord); - if (!after(scb->end_seq, tp->high_seq)) - flag |= FLAG_ORIG_SACK_ACKED; + if (!after(scb->end_seq, tp->high_seq)) + flag |= FLAG_ORIG_SACK_ACKED; + } } if (sacked & TCPCB_SACKED_ACKED) -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/