[{"id":1797278,"web_url":"http://patchwork.ozlabs.org/comment/1797278/","msgid":"<5FF5EDEE-FF34-43E0-9DFA-6CBDB206360D@fb.com>","list_archive_url":null,"date":"2017-11-01T13:47:17","subject":"Re: [PATCH] tcp_nv: fix division by zero in tcpnv_acked()","submitter":{"id":66772,"url":"http://patchwork.ozlabs.org/api/people/66772/","name":"Lawrence Brakmo","email":"brakmo@fb.com"},"content":"Thank you for finding and fixing this.\r\n\r\nOn 11/1/17, 6:32 AM, \"Konstantin Khlebnikov\" wrote:\r\n\r\n Average RTT could become zero. This happened in real life at least twice.\r\n This patch treats zero as 1us.\r\n \r\n Signed-off-by: Konstantin Khlebnikov khlebnikov@yandex-team.ru\r\nAcked-by: Lawrence Brakmo \r\n ---\r\n net/ipv4/tcp_nv.c | 2 +-\r\n 1 file changed, 1 insertion(+), 1 deletion(-)\r\n \r\n diff --git a/net/ipv4/tcp_nv.c b/net/ipv4/tcp_nv.c\r\n index 1ff73982e28c..125fc1450b01 100644\r\n --- a/net/ipv4/tcp_nv.c\r\n +++ b/net/ipv4/tcp_nv.c\r\n @@ -252,7 +252,7 @@ static void tcpnv_acked(struct sock *sk, const struct ack_sample *sample)\r\n \r\n \t/* rate in 100's bits per second */\r\n \trate64 = ((u64)sample->in_flight) * 8000000;\r\n -\trate = (u32)div64_u64(rate64, (u64)(avg_rtt * 100));\r\n +\trate = (u32)div64_u64(rate64, (u64)(avg_rtt ?: 1) * 100);\r\n \r\n \t/* Remember the maximum rate seen during this RTT\r\n \t * Note: It may be more than one RTT. This function should be","headers":{"Return-Path":"","X-Original-To":"patchwork-incoming@ozlabs.org","Delivered-To":"patchwork-incoming@ozlabs.org","Authentication-Results":["ozlabs.org;\n\tspf=none (mailfrom) smtp.mailfrom=vger.kernel.org\n\t(client-ip=209.132.180.67; helo=vger.kernel.org;\n\tenvelope-from=netdev-owner@vger.kernel.org;\n\treceiver=)","ozlabs.org; dkim=pass (1024-bit key;\n\tunprotected) header.d=fb.com header.i=@fb.com header.b=\"I2dStzJz\";\n\tdkim=pass (1024-bit key;\n\tunprotected) header.d=fb.onmicrosoft.com header.i=@fb.onmicrosoft.com\n\theader.b=\"T9j/KH5F\"; dkim-atps=neutral"],"Received":["from vger.kernel.org (vger.kernel.org [209.132.180.67])\n\tby ozlabs.org (Postfix) with ESMTP id 3yRqKz56QWz9rxl\n\tfor ;\n\tThu, 2 Nov 2017 00:48:07 +1100 (AEDT)","(majordomo@vger.kernel.org) by vger.kernel.org via listexpand\n\tid S1754576AbdKANrx (ORCPT );\n\tWed, 1 Nov 2017 09:47:53 -0400","from mx0b-00082601.pphosted.com ([67.231.153.30]:51076 \"EHLO\n\tmx0a-00082601.pphosted.com\" rhost-flags-OK-OK-OK-FAIL)\n\tby vger.kernel.org with ESMTP id S1751738AbdKANrv (ORCPT\n\t); Wed, 1 Nov 2017 09:47:51 -0400","from pps.filterd (m0001303.ppops.net [127.0.0.1])\n\tby m0001303.ppops.net (8.16.0.21/8.16.0.21) with SMTP id\n\tvA1DgKHQ020900; Wed, 1 Nov 2017 06:47:20 -0700","from mail.thefacebook.com ([199.201.64.23])\n\tby m0001303.ppops.net with ESMTP id 2dy10wkvgy-3\n\t(version=TLSv1 cipher=ECDHE-RSA-AES256-SHA bits=256 verify=NOT);\n\tWed, 01 Nov 2017 06:47:20 -0700","from NAM03-DM3-obe.outbound.protection.outlook.com (192.168.54.28)\n\tby o365-in.thefacebook.com (192.168.16.19) with Microsoft SMTP\n\tServer (TLS) id 14.3.361.1; Wed, 1 Nov 2017 06:47:19 -0700","from CY4PR15MB1671.namprd15.prod.outlook.com (10.175.120.146) by\n\tCY4PR15MB1670.namprd15.prod.outlook.com (10.175.120.145) with\n\tMicrosoft SMTP Server (version=TLS1_2,\n\tcipher=TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384_P256) id\n\t15.20.178.6; Wed, 1 Nov 2017 13:47:17 +0000","from CY4PR15MB1671.namprd15.prod.outlook.com ([10.175.120.146]) by\n\tCY4PR15MB1671.namprd15.prod.outlook.com ([10.175.120.146]) with\n\tmapi id 15.20.0178.014; Wed, 1 Nov 2017 13:47:17 +0000"],"DKIM-Signature":["v=1; a=rsa-sha256; c=relaxed/relaxed; d=fb.com;\n\th=from : to : cc : subject\n\t: date : message-id : references : in-reply-to : content-type :\n\tcontent-id\n\t: content-transfer-encoding : mime-version; s=facebook;\n\tbh=AR9zv9pdkOARcqK0MWtfFSX73PHwmMABf3ECgiswzO0=;\n\tb=I2dStzJzO26RhnQJUzTJOgxALAYr7zb55Wmw5ddGPXSqPDwBec8nThDKRqYRjKwfc1Ow\n\tZzE5J7Rwo8inIDA5KCfgY4ms0ZqElwy1ODVDbhNZgFJGEt6gOR9hdfJJKjvwzdpy6CCh\n\toecuApLiUrzmaufoOyeUaWuVDtAdw69ygvI= ","v=1; a=rsa-sha256; c=relaxed/relaxed; d=fb.onmicrosoft.com; \n\ts=selector1-fb-com;\n\th=From:Date:Subject:Message-ID:Content-Type:MIME-Version; \n\tbh=AR9zv9pdkOARcqK0MWtfFSX73PHwmMABf3ECgiswzO0=;\n\tb=T9j/KH5F6D9Vvo86qwmowcS2AJktKVfoVFWbjpBSAQKzUaa+OaOcVlwJ6z2ikU24lcZ29xEDWgF3L/kODlDc/MfkFLaBGDXM8V1Yp+yk6yi7eklsVPbUIEAfGvTpaHdAkAeWch3rsWCW8/RNvDsClA9gPbNof2Y2VFT1cB8BlHE="],"From":"Lawrence Brakmo ","To":"Konstantin Khlebnikov ,\n\t\"netdev@vger.kernel.org\" ,\n\t\"David S. Miller\" ","CC":"Alexey Kuznetsov ,\n\tHideaki YOSHIFUJI ,\n\t\"linux-kernel@vger.kernel.org\" ","Subject":"Re: [PATCH] tcp_nv: fix division by zero in tcpnv_acked()","Thread-Topic":"[PATCH] tcp_nv: fix division by zero in tcpnv_acked()","Thread-Index":"AQHTUxXna/4eJRcF8k6uCcFf0dWyPKL/ia8A","Date":"Wed, 1 Nov 2017 13:47:17 +0000","Message-ID":"<5FF5EDEE-FF34-43E0-9DFA-6CBDB206360D@fb.com>","References":"<150954313588.153848.10192893966808917578.stgit@buzz>","In-Reply-To":"<150954313588.153848.10192893966808917578.stgit@buzz>","Accept-Language":"en-US","Content-Language":"en-US","X-MS-Has-Attach":"","X-MS-TNEF-Correlator":"","user-agent":"Microsoft-MacOutlook/f.26.0.170902","x-originating-ip":"[2620:10d:c090:180::1:397a]","x-ms-publictraffictype":"Email","x-microsoft-exchange-diagnostics":"1; CY4PR15MB1670;\n\t20:LHmC4YQKw/DbLQUDVWs05dsKtJ0Tx4uIbYLWaf6LX0JwNVWNkGpVO9D4aziLN84mw0vDoHXYbcLshHu15khRd/IoAtS7kvNkftfl/T2vs1FtC98as5qCURsLkA6oxl/luIuMJS2Ru/74+UkNaAjV2wD775C5S3GEz72SP9GbttI=","x-ms-exchange-antispam-srfa-diagnostics":"SSOS;","x-ms-office365-filtering-correlation-id":"634b3547-1e02-4803-6974-08d5212f10e6","x-microsoft-antispam":"UriScan:; BCL:0; PCL:0;\n\tRULEID:(22001)(4534020)(4602075)(2017052603199);\n\tSRVR:CY4PR15MB1670; ","x-ms-traffictypediagnostic":"CY4PR15MB1670:","x-exchange-antispam-report-test":"UriScan:(67672495146484);","x-microsoft-antispam-prvs":"","x-exchange-antispam-report-cfa-test":"BCL:0; PCL:0;\n\tRULEID:(100000700101)(100105000095)(100000701101)(100105300095)(100000702101)(100105100095)(11241501159)(6040450)(2401047)(8121501046)(5005006)(100000703101)(100105400095)(3002001)(93006095)(93001095)(10201501046)(3231020)(6041248)(20161123558100)(20161123564025)(20161123560025)(20161123562025)(201703131423075)(201702281528075)(201703061421075)(201703061406153)(20161123555025)(6072148)(201708071742011)(100000704101)(100105200095)(100000705101)(100105500095);\n\tSRVR:CY4PR15MB1670; BCL:0; PCL:0;\n\tRULEID:(100000800101)(100110000095)(100000801101)(100110300095)(100000802101)(100110100095)(100000803101)(100110400095)(100000804101)(100110200095)(100000805101)(100110500095);\n\tSRVR:CY4PR15MB1670; ","x-forefront-prvs":"0478C23FE0","x-forefront-antispam-report":"SFV:NSPM;\n\tSFS:(10019020)(6009001)(346002)(376002)(199003)(24454002)(189002)(2900100001)(86362001)(33656002)(2906002)(3280700002)(8936002)(53936002)(4477795004)(6246003)(3660700001)(76176999)(54356999)(54906003)(97736004)(50986999)(5660300001)(82746002)(229853002)(2950100002)(83716003)(101416001)(478600001)(110136005)(316002)(25786009)(189998001)(77096006)(6486002)(58126008)(68736007)(105586002)(14454004)(345774005)(106356001)(6116002)(305945005)(102836003)(6512007)(81156014)(81166006)(8676002)(53546010)(99286003)(83506002)(36756003)(6506006)(6436002)(4326008)(7736002)(2501003);\n\tDIR:OUT; SFP:1102; SCL:1; SRVR:CY4PR15MB1670;\n\tH:CY4PR15MB1671.namprd15.prod.outlook.com; FPR:; SPF:None;\n\tPTR:InfoNoRecords; A:1; MX:1; LANG:en; ","received-spf":"None (protection.outlook.com: fb.com does not designate\n\tpermitted sender hosts)","spamdiagnosticoutput":"1:99","spamdiagnosticmetadata":"NSPM","Content-Type":"text/plain; charset=\"utf-8\"","Content-ID":"<85C36806C43CA144A375021662C5F18F@namprd15.prod.outlook.com>","Content-Transfer-Encoding":"base64","MIME-Version":"1.0","X-MS-Exchange-CrossTenant-Network-Message-Id":"634b3547-1e02-4803-6974-08d5212f10e6","X-MS-Exchange-CrossTenant-originalarrivaltime":"01 Nov 2017 13:47:17.2570\n\t(UTC)","X-MS-Exchange-CrossTenant-fromentityheader":"Hosted","X-MS-Exchange-CrossTenant-id":"8ae927fe-1255-47a7-a2af-5f3a069daaa2","X-MS-Exchange-Transport-CrossTenantHeadersStamped":"CY4PR15MB1670","X-OriginatorOrg":"fb.com","X-Proofpoint-Spam-Reason":"safe","X-FB-Internal":"Safe","X-Proofpoint-Virus-Version":"vendor=fsecure engine=2.50.10432:, ,\n\tdefinitions=2017-11-01_03:, , signatures=0","Sender":"netdev-owner@vger.kernel.org","Precedence":"bulk","List-ID":"","X-Mailing-List":"netdev@vger.kernel.org"}},{"id":1797286,"web_url":"http://patchwork.ozlabs.org/comment/1797286/","msgid":"<20171101151351.42e699cf@shemminger-XPS-13-9360>","list_archive_url":null,"date":"2017-11-01T14:13:51","subject":"Re: [PATCH] tcp_nv: fix division by zero in tcpnv_acked()","submitter":{"id":21389,"url":"http://patchwork.ozlabs.org/api/people/21389/","name":"Stephen Hemminger","email":"stephen@networkplumber.org"},"content":"On Wed, 1 Nov 2017 13:47:17 +0000\nLawrence Brakmo wrote:\n\n> Thank you for finding and fixing this.\n> \n> On 11/1/17, 6:32 AM, \"Konstantin Khlebnikov\" wrote:\n> \n> Average RTT could become zero. This happened in real life at least twice.\n> This patch treats zero as 1us.\n> \n> Signed-off-by: Konstantin Khlebnikov khlebnikov@yandex-team.ru\n> Acked-by: Lawrence Brakmo \n> ---\n> net/ipv4/tcp_nv.c | 2 +-\n> 1 file changed, 1 insertion(+), 1 deletion(-)\n> \n> diff --git a/net/ipv4/tcp_nv.c b/net/ipv4/tcp_nv.c\n> index 1ff73982e28c..125fc1450b01 100644\n> --- a/net/ipv4/tcp_nv.c\n> +++ b/net/ipv4/tcp_nv.c\n> @@ -252,7 +252,7 @@ static void tcpnv_acked(struct sock *sk, const struct ack_sample *sample)\n> \n> \t/* rate in 100's bits per second */\n> \trate64 = ((u64)sample->in_flight) * 8000000;\n> -\trate = (u32)div64_u64(rate64, (u64)(avg_rtt * 100));\n> +\trate = (u32)div64_u64(rate64, (u64)(avg_rtt ?: 1) * 100);\n\nWhy is this code using expensive 64 bit by 64 bit divide when avg_rtt should never be bigger\nthan 32 bits?","headers":{"Return-Path":"","X-Original-To":"patchwork-incoming@ozlabs.org","Delivered-To":"patchwork-incoming@ozlabs.org","Authentication-Results":["ozlabs.org;\n\tspf=none (mailfrom) smtp.mailfrom=vger.kernel.org\n\t(client-ip=209.132.180.67; helo=vger.kernel.org;\n\tenvelope-from=netdev-owner@vger.kernel.org;\n\treceiver=)","ozlabs.org; dkim=pass (2048-bit key;\n\tunprotected) header.d=networkplumber-org.20150623.gappssmtp.com\n\theader.i=@networkplumber-org.20150623.gappssmtp.com\n\theader.b=\"F/Q9ET82\"; dkim-atps=neutral"],"Received":["from vger.kernel.org (vger.kernel.org [209.132.180.67])\n\tby ozlabs.org (Postfix) with ESMTP id 3yRqwj3Yy0z9sNd\n\tfor ;\n\tThu, 2 Nov 2017 01:14:45 +1100 (AEDT)","(majordomo@vger.kernel.org) by vger.kernel.org via listexpand\n\tid S1754657AbdKAOOU (ORCPT );\n\tWed, 1 Nov 2017 10:14:20 -0400","from mail-lf0-f67.google.com ([209.85.215.67]:44088 \"EHLO\n\tmail-lf0-f67.google.com\" rhost-flags-OK-OK-OK-OK) by vger.kernel.org\n\twith ESMTP id S1754623AbdKAOOS (ORCPT\n\t); Wed, 1 Nov 2017 10:14:18 -0400","by mail-lf0-f67.google.com with SMTP id 75so2713050lfx.1\n\tfor ; Wed, 01 Nov 2017 07:14:18 -0700 (PDT)","from shemminger-XPS-13-9360\n\t(static-92-33-18-3.sme.bredbandsbolaget.se. [92.33.18.3])\n\tby smtp.gmail.com with ESMTPSA id\n\tu19sm117600lfc.89.2017.11.01.07.14.16\n\t(version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256);\n\tWed, 01 Nov 2017 07:14:17 -0700 (PDT)"],"DKIM-Signature":"v=1; a=rsa-sha256; c=relaxed/relaxed;\n\td=networkplumber-org.20150623.gappssmtp.com; s=20150623;\n\th=date:from:to:cc:subject:message-id:in-reply-to:references\n\t:mime-version:content-transfer-encoding;\n\tbh=owxZMawBDBc9QbOYV0ti4tsSg9t/OLxeXE+ytzescpM=;\n\tb=F/Q9ET82zHYWOK/xTBpqZfOcUAARlsgZv8q72Flhotl6qTv7ziZrQhk4mRujmFriIx\n\txjgFzFYC6VhDXbJj8cQF05zPD1o2FvsNVu/83jfDiDYMB0dpmg6+R6RLJXMsaCUHiB91\n\tFawXknf0a1LKlHSdNHmNbrYJnyx/cMhTo4J6Lj4DLFrmV2+cbi/cxeBzvTKA6bb7rR01\n\t9JUraKQ3YhQPqN+oTjYnkFP2VAPb8jN+m7LI/xXIQd/De645ZocnAL0xhoHDK2nSVBz/\n\ttQSWsLTBHY0Hhyx/Hv9Ma1KWF5mhl8VukwvygAhipQiBscK8pPUeR2/fdMb48/wdaR7g\n\t06CQ==","X-Google-DKIM-Signature":"v=1; a=rsa-sha256; c=relaxed/relaxed;\n\td=1e100.net; s=20161025;\n\th=x-gm-message-state:date:from:to:cc:subject:message-id:in-reply-to\n\t:references:mime-version:content-transfer-encoding;\n\tbh=owxZMawBDBc9QbOYV0ti4tsSg9t/OLxeXE+ytzescpM=;\n\tb=KKf89tUqyPX0+UbFaFC7poaLa9iuY85EauRNQnmhJobtIbZJ13ENF9xHDLJgkaFK0o\n\t32nQIaBRKE2BDCefvm5hhUgk9IYJ1i1M4dZkU3SK+Me4QwSpzrsURZYEHG/213ruc8VL\n\tT1XK1oqeqxnzbAjXtDTVVwH/LqzKMQM7DbQ3EZn27hutvx5yxXquRJBSUf5oy2Uvedxj\n\tHgAdW9saThUzxhH4Ocx7LPic4hUZZASCggBm84qfBf2hrwPtiYb6tnul5U8h02Xdxech\n\tgRzdMXw8sjDG8CqeD2594UQu0aJUK0JWEqM/ag0f2aGjyAUm46tVrZnev7N50aM3soIi\n\tH7wQ==","X-Gm-Message-State":"AMCzsaX7MVhe9fin1T1zNEdHDODnikyeIYc2dbJtJvUp5KyvaOrr/xKf\n\tPJpezCN3RsOgZ8xA5bdNioi5iQ==","X-Google-Smtp-Source":"ABhQp+S1Z3q44iAjLO5LYynQLdmssV/QYEpE5pkNPHibvJaXtARc2gO+stj2/jJ2Akgsd9am6J2f1Q==","X-Received":"by 10.46.57.3 with SMTP id g3mr2484270lja.77.1509545657266;\n\tWed, 01 Nov 2017 07:14:17 -0700 (PDT)","Date":"Wed, 1 Nov 2017 15:13:51 +0100","From":"Stephen Hemminger ","To":"Lawrence Brakmo ","Cc":"Konstantin Khlebnikov ,\n\t\"netdev@vger.kernel.org\" ,\n\t\"David S. Miller\" ,\n\tAlexey Kuznetsov ,\n\tHideaki YOSHIFUJI ,\n\t\"linux-kernel@vger.kernel.org\" ","Subject":"Re: [PATCH] tcp_nv: fix division by zero in tcpnv_acked()","Message-ID":"<20171101151351.42e699cf@shemminger-XPS-13-9360>","In-Reply-To":"<5FF5EDEE-FF34-43E0-9DFA-6CBDB206360D@fb.com>","References":"<150954313588.153848.10192893966808917578.stgit@buzz>\n\t<5FF5EDEE-FF34-43E0-9DFA-6CBDB206360D@fb.com>","MIME-Version":"1.0","Content-Type":"text/plain; charset=US-ASCII","Content-Transfer-Encoding":"7bit","Sender":"netdev-owner@vger.kernel.org","Precedence":"bulk","List-ID":"","X-Mailing-List":"netdev@vger.kernel.org"}},{"id":1797288,"web_url":"http://patchwork.ozlabs.org/comment/1797288/","msgid":"<1509545828.3828.44.camel@edumazet-glaptop3.roam.corp.google.com>","list_archive_url":null,"date":"2017-11-01T14:17:08","subject":"Re: [PATCH] tcp_nv: fix division by zero in tcpnv_acked()","submitter":{"id":2404,"url":"http://patchwork.ozlabs.org/api/people/2404/","name":"Eric Dumazet","email":"eric.dumazet@gmail.com"},"content":"On Wed, 2017-11-01 at 16:32 +0300, Konstantin Khlebnikov wrote:\n> Average RTT could become zero. This happened in real life at least twice.\n> This patch treats zero as 1us.\n> \n> Signed-off-by: Konstantin Khlebnikov \n> ---\n> net/ipv4/tcp_nv.c | 2 +-\n> 1 file changed, 1 insertion(+), 1 deletion(-)\n> \n> diff --git a/net/ipv4/tcp_nv.c b/net/ipv4/tcp_nv.c\n> index 1ff73982e28c..125fc1450b01 100644\n> --- a/net/ipv4/tcp_nv.c\n> +++ b/net/ipv4/tcp_nv.c\n> @@ -252,7 +252,7 @@ static void tcpnv_acked(struct sock *sk, const struct ack_sample *sample)\n> \n> \t/* rate in 100's bits per second */\n> \trate64 = ((u64)sample->in_flight) * 8000000;\n> -\trate = (u32)div64_u64(rate64, (u64)(avg_rtt * 100));\n> +\trate = (u32)div64_u64(rate64, (u64)(avg_rtt ?: 1) * 100);\n> \n> \t/* Remember the maximum rate seen during this RTT\n> \t * Note: It may be more than one RTT. This function should be\n> \n\nBTW, this div64_u64() could be replaced by a u32 divide (aka do_div()),\nslightly less expensive.\n\n\nrate64 = ((u64)sample->in_flight) * 80000;\ndo_div(rate64, avg_rtt ?: 1);\nrate = (u32)rate64;","headers":{"Return-Path":"","X-Original-To":"patchwork-incoming@ozlabs.org","Delivered-To":"patchwork-incoming@ozlabs.org","Authentication-Results":["ozlabs.org;\n\tspf=none (mailfrom) smtp.mailfrom=vger.kernel.org\n\t(client-ip=209.132.180.67; helo=vger.kernel.org;\n\tenvelope-from=netdev-owner@vger.kernel.org;\n\treceiver=)","ozlabs.org; dkim=pass (2048-bit key;\n\tunprotected) header.d=gmail.com header.i=@gmail.com\n\theader.b=\"h+/Og57y\"; dkim-atps=neutral"],"Received":["from vger.kernel.org (vger.kernel.org [209.132.180.67])\n\tby ozlabs.org (Postfix) with ESMTP id 3yRr0h1VzMz9sPs\n\tfor ;\n\tThu, 2 Nov 2017 01:18:12 +1100 (AEDT)","(majordomo@vger.kernel.org) by vger.kernel.org via listexpand\n\tid S1754672AbdKAORr (ORCPT );\n\tWed, 1 Nov 2017 10:17:47 -0400","from mail-pf0-f193.google.com ([209.85.192.193]:53134 \"EHLO\n\tmail-pf0-f193.google.com\" rhost-flags-OK-OK-OK-OK) by vger.kernel.org\n\twith ESMTP id S1754671AbdKAORL (ORCPT\n\t); Wed, 1 Nov 2017 10:17:11 -0400","by mail-pf0-f193.google.com with SMTP id e64so2066800pfk.9;\n\tWed, 01 Nov 2017 07:17:11 -0700 (PDT)","from [192.168.86.171] (c-67-180-167-114.hsd1.ca.comcast.net.\n\t[67.180.167.114]) by smtp.googlemail.com with ESMTPSA id\n\tp83sm1695819pfd.61.2017.11.01.07.17.08\n\t(version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128);\n\tWed, 01 Nov 2017 07:17:09 -0700 (PDT)"],"DKIM-Signature":"v=1; a=rsa-sha256; c=relaxed/relaxed;\n\td=gmail.com; s=20161025;\n\th=message-id:subject:from:to:cc:date:in-reply-to:references\n\t:mime-version:content-transfer-encoding;\n\tbh=Aqu0KhcoOLWZNY7o6gI6n8dmKRIsM52qOg3dhNtng28=;\n\tb=h+/Og57y6YTka9om2Z+/HKv+wNP2mgIYTT3CA0ItEmkcu0wbNcgWAHMC17k0OuGbK9\n\taKENgpMN1/EtPRHWdJPDlKnmUyDu46UFgowMVTr/XtOMBqgXfLHsc088sw94gH9+EOrw\n\tNSuvzF9fjp9tVv2YG9o4B4WOl/vOZvEMnf2kcNPJhKfjdprcUtoYOjz98Q/dldbxqn1U\n\tvs+ebC9C5pu9aLIs3DIBk8j8Nk7FhPZiYaLZCMQqjNx9c9+pZSNv41B0zdSJXV3PgX2Z\n\t90C6ezIgrn5lbeR6OoGue9s3m17k9tWqLtuxny4AIiPK8jNKS+k36jjiSTfzB+wBNSc+\n\t5Efw==","X-Google-DKIM-Signature":"v=1; a=rsa-sha256; c=relaxed/relaxed;\n\td=1e100.net; s=20161025;\n\th=x-gm-message-state:message-id:subject:from:to:cc:date:in-reply-to\n\t:references:mime-version:content-transfer-encoding;\n\tbh=Aqu0KhcoOLWZNY7o6gI6n8dmKRIsM52qOg3dhNtng28=;\n\tb=PY6hkEJsGTjZhKATYm9UXgzgalOSnSouCkBAgxfEltjSICtoMYClog5HgtsxqAtOMP\n\t7DBU3V1Wat6wBWMz3YFZ5boR0WB8T5a1FDvEx8n5Cj/kTyRQf00Y/znoK7Plp1M7F7Gr\n\tP74SuSXYpFIoAs6QKz3LLmTT1tHjJVesU1nVIpHeox0dyidMqieAoYJE+v/6j6QjOPRD\n\taju9gGeLDRBy68ht4/esQAiOIxmyinCBJgqa2rZJEcaiFyJYUblHPQ2lR00E6zDmIyUl\n\tSgGnaG8YdzkXN6eAS+yEV4M/Mlvq+NITfiE1E68biTpVZzUD0Uvcqpk1flfsmeTUKjX1\n\twlTg==","X-Gm-Message-State":"AMCzsaWogDfkUbij22mlUBHYRf4Ydn7hw7xrSi/B7Yq0/gZ/7BjALQ3y\n\tGZGaBNC2/TVKztmWREC3Krk=","X-Google-Smtp-Source":"ABhQp+SnXZmtk4RMb6XNvM8YLXZOF6sgmDWhLypdUpKEp+mGqKP13foHtHIiyVsDRWiz7+pO99ysTA==","X-Received":"by 10.99.98.70 with SMTP id w67mr6601645pgb.9.1509545831178;\n\tWed, 01 Nov 2017 07:17:11 -0700 (PDT)","Message-ID":"<1509545828.3828.44.camel@edumazet-glaptop3.roam.corp.google.com>","Subject":"Re: [PATCH] tcp_nv: fix division by zero in tcpnv_acked()","From":"Eric Dumazet ","To":"Konstantin Khlebnikov ","Cc":"netdev@vger.kernel.org, \"David S. Miller\" ,\n\tLawrence Brakmo , Alexey Kuznetsov ,\n\tHideaki YOSHIFUJI , linux-kernel@vger.kernel.org","Date":"Wed, 01 Nov 2017 07:17:08 -0700","In-Reply-To":"<150954313588.153848.10192893966808917578.stgit@buzz>","References":"<150954313588.153848.10192893966808917578.stgit@buzz>","Content-Type":"text/plain; charset=\"UTF-8\"","X-Mailer":"Evolution 3.10.4-0ubuntu2 ","Mime-Version":"1.0","Content-Transfer-Encoding":"7bit","Sender":"netdev-owner@vger.kernel.org","Precedence":"bulk","List-ID":"","X-Mailing-List":"netdev@vger.kernel.org"}},{"id":1797673,"web_url":"http://patchwork.ozlabs.org/comment/1797673/","msgid":"<20171102.161755.1469652396797608567.davem@davemloft.net>","list_archive_url":null,"date":"2017-11-02T07:17:55","subject":"Re: [PATCH] tcp_nv: fix division by zero in tcpnv_acked()","submitter":{"id":15,"url":"http://patchwork.ozlabs.org/api/people/15/","name":"David Miller","email":"davem@davemloft.net"},"content":"From: Konstantin Khlebnikov \nDate: Wed, 01 Nov 2017 16:32:15 +0300\n\n> Average RTT could become zero. This happened in real life at least twice.\n> This patch treats zero as 1us.\n> \n> Signed-off-by: Konstantin Khlebnikov \n\nApplied and queued up for -stable, thank you.\n\nIndeed, as others have mentioned, a cheaper divide should be used\nbut that is a separate issue from this fix and therefore should be\ndone in a separate patch.\n\nThanks again.","headers":{"Return-Path":"","X-Original-To":"patchwork-incoming@ozlabs.org","Delivered-To":"patchwork-incoming@ozlabs.org","Authentication-Results":"ozlabs.org;\n\tspf=none (mailfrom) smtp.mailfrom=vger.kernel.org\n\t(client-ip=209.132.180.67; helo=vger.kernel.org;\n\tenvelope-from=netdev-owner@vger.kernel.org;\n\treceiver=)","Received":["from vger.kernel.org (vger.kernel.org [209.132.180.67])\n\tby ozlabs.org (Postfix) with ESMTP id 3ySGdc1yMVz9t2l\n\tfor ;\n\tThu, 2 Nov 2017 18:18:12 +1100 (AEDT)","(majordomo@vger.kernel.org) by vger.kernel.org via listexpand\n\tid S1754817AbdKBHSA (ORCPT );\n\tThu, 2 Nov 2017 03:18:00 -0400","from shards.monkeyblade.net ([184.105.139.130]:44262 \"EHLO\n\tshards.monkeyblade.net\" rhost-flags-OK-OK-OK-OK) by vger.kernel.org\n\twith ESMTP id S1751567AbdKBHR7 (ORCPT\n\t); Thu, 2 Nov 2017 03:17:59 -0400","from localhost (unknown [106.252.28.196])\n\t(using TLSv1 with cipher AES256-SHA (256/256 bits))\n\t(Client did not present a certificate)\n\t(Authenticated sender: davem-davemloft)\n\tby shards.monkeyblade.net (Postfix) with ESMTPSA id F20491363BC69;\n\tThu, 2 Nov 2017 00:17:57 -0700 (PDT)"],"Date":"Thu, 02 Nov 2017 16:17:55 +0900 (KST)","Message-Id":"<20171102.161755.1469652396797608567.davem@davemloft.net>","To":"khlebnikov@yandex-team.ru","Cc":"netdev@vger.kernel.org, brakmo@fb.com, kuznet@ms2.inr.ac.ru,\n\tyoshfuji@linux-ipv6.org, linux-kernel@vger.kernel.org","Subject":"Re: [PATCH] tcp_nv: fix division by zero in tcpnv_acked()","From":"David Miller ","In-Reply-To":"<150954313588.153848.10192893966808917578.stgit@buzz>","References":"<150954313588.153848.10192893966808917578.stgit@buzz>","X-Mailer":"Mew version 6.7 on Emacs 25.3 / Mule 6.0 (HANACHIRUSATO)","Mime-Version":"1.0","Content-Type":"Text/Plain; charset=us-ascii","Content-Transfer-Encoding":"7bit","X-Greylist":"Sender succeeded SMTP AUTH, not delayed by\n\tmilter-greylist-4.5.12 (shards.monkeyblade.net\n\t[149.20.54.216]); Thu, 02 Nov 2017 00:17:59 -0700 (PDT)","Sender":"netdev-owner@vger.kernel.org","Precedence":"bulk","List-ID":"","X-Mailing-List":"netdev@vger.kernel.org"}}]