From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-3.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id A26CFC5519F for ; Wed, 18 Nov 2020 09:18:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 54C542467D for ; Wed, 18 Nov 2020 09:18:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726476AbgKRJS3 convert rfc822-to-8bit (ORCPT ); Wed, 18 Nov 2020 04:18:29 -0500 Received: from eu-smtp-delivery-151.mimecast.com ([207.82.80.151]:52265 "EHLO eu-smtp-delivery-151.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725804AbgKRJS3 (ORCPT ); Wed, 18 Nov 2020 04:18:29 -0500 Received: from AcuMS.aculab.com (156.67.243.126 [156.67.243.126]) (Using TLS) by relay.mimecast.com with ESMTP id uk-mta-94-FSSv3gobMvWUdqkIex0ELA-1; Wed, 18 Nov 2020 09:18:25 +0000 X-MC-Unique: FSSv3gobMvWUdqkIex0ELA-1 Received: from AcuMS.Aculab.com (fd9f:af1c:a25b:0:43c:695e:880f:8750) by AcuMS.aculab.com (fd9f:af1c:a25b:0:43c:695e:880f:8750) with Microsoft SMTP Server (TLS) id 15.0.1347.2; Wed, 18 Nov 2020 09:18:24 +0000 Received: from AcuMS.Aculab.com ([fe80::43c:695e:880f:8750]) by AcuMS.aculab.com ([fe80::43c:695e:880f:8750%12]) with mapi id 15.00.1347.000; Wed, 18 Nov 2020 09:18:24 +0000 From: David Laight To: 'Kuniyuki Iwashima' , "David S . Miller" , Jakub Kicinski , Eric Dumazet , Alexei Starovoitov , Daniel Borkmann CC: Benjamin Herrenschmidt , Kuniyuki Iwashima , "bpf@vger.kernel.org" , "netdev@vger.kernel.org" , "linux-kernel@vger.kernel.org" Subject: RE: [RFC PATCH bpf-next 0/8] Socket migration for SO_REUSEPORT. Thread-Topic: [RFC PATCH bpf-next 0/8] Socket migration for SO_REUSEPORT. Thread-Index: AQHWvMXedAT5e1uWx0Go2ulX1CPcBqnNnI0w Date: Wed, 18 Nov 2020 09:18:24 +0000 Message-ID: <01a5c211a87a4dd69940e19c2ff00334@AcuMS.aculab.com> References: <20201117094023.3685-1-kuniyu@amazon.co.jp> In-Reply-To: <20201117094023.3685-1-kuniyu@amazon.co.jp> Accept-Language: en-GB, en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-ms-exchange-transport-fromentityheader: Hosted x-originating-ip: [10.202.205.107] MIME-Version: 1.0 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=C51A453 smtp.mailfrom=david.laight@aculab.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: aculab.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org From: Kuniyuki Iwashima > Sent: 17 November 2020 09:40 > > The SO_REUSEPORT option allows sockets to listen on the same port and to > accept connections evenly. However, there is a defect in the current > implementation. When a SYN packet is received, the connection is tied to a > listening socket. Accordingly, when the listener is closed, in-flight > requests during the three-way handshake and child sockets in the accept > queue are dropped even if other listeners could accept such connections. > > This situation can happen when various server management tools restart > server (such as nginx) processes. For instance, when we change nginx > configurations and restart it, it spins up new workers that respect the new > configuration and closes all listeners on the old workers, resulting in > in-flight ACK of 3WHS is responded by RST. Can't you do something to stop new connections being queued (like setting the 'backlog' to zero), then carry on doing accept()s for a guard time (or until the queue length is zero) before finally closing the listening socket. David - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales)