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=-10.1 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=ham 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 51DC8C433E0 for ; Tue, 16 Mar 2021 14:48:23 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id D4B9A65085 for ; Tue, 16 Mar 2021 14:48:22 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D4B9A65085 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:53632 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1lMAzd-0006fO-Uo for qemu-devel@archiver.kernel.org; Tue, 16 Mar 2021 10:48:21 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:45290) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lMAtH-0007xi-I0 for qemu-devel@nongnu.org; Tue, 16 Mar 2021 10:41:47 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:25913) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1lMAtF-0004BM-TB for qemu-devel@nongnu.org; Tue, 16 Mar 2021 10:41:47 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1615905705; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=wTva5Bj6uWnxCUvkQRCNaMHgi7w3X+VttkiPYgifBrQ=; b=IEqrqXcLmXHaAKqJhaAzNVSj+tYHbwqaSipa9ZUZBLqeIB1AhF8TW/3yS5pnCwBzJLFPi9 t0jj4mQsfCSzP0bANhle5beBSJZ6UX1Rq8ANHDVTMD7czIpC3Ol26MI8sn+YSnklhOHSOK xYsoVJEaJsCe1XIs9xLDYTpRLyapSzI= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-561-XmQ_l36QMvuVqMd4IjCdVQ-1; Tue, 16 Mar 2021 10:41:41 -0400 X-MC-Unique: XmQ_l36QMvuVqMd4IjCdVQ-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 023021015C84; Tue, 16 Mar 2021 14:41:39 +0000 (UTC) Received: from [10.3.113.66] (ovpn-113-66.phx2.redhat.com [10.3.113.66]) by smtp.corp.redhat.com (Postfix) with ESMTPS id E5CFB6091A; Tue, 16 Mar 2021 14:41:36 +0000 (UTC) Subject: Re: [PATCH 0/7] block/nbd: decouple reconnect from drain To: Roman Kagan , qemu-devel@nongnu.org References: <20210315060611.2989049-1-rvkagan@yandex-team.ru> From: Eric Blake Organization: Red Hat, Inc. Message-ID: Date: Tue, 16 Mar 2021 09:41:36 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.8.0 MIME-Version: 1.0 In-Reply-To: <20210315060611.2989049-1-rvkagan@yandex-team.ru> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=eblake@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=216.205.24.124; envelope-from=eblake@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -29 X-Spam_score: -3.0 X-Spam_bar: --- X-Spam_report: (-3.0 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.25, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, NICE_REPLY_A=-0.001, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Kevin Wolf , Vladimir Sementsov-Ogievskiy , qemu-block@nongnu.org, yc-core@yandex-team.ru, Max Reitz Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 3/15/21 1:06 AM, Roman Kagan wrote: > The reconnection logic doesn't need to stop while in a drained section. > Moreover it has to be active during the drained section, as the requests > that were caught in-flight with the connection to the server broken can > only usefully get drained if the connection is restored. Otherwise such > requests can only either stall resulting in a deadlock (before > 8c517de24a), or be aborted defeating the purpose of the reconnection > machinery (after 8c517de24a). > > This series aims to just stop messing with the drained section in the > reconnection code. > > While doing so it undoes the effect of 5ad81b4946 ("nbd: Restrict > connection_co reentrance"); as I've missed the point of that commit I'd > appreciate more scrutiny in this area. Soft freeze is today. I'm leaning towards declaring this series as a bug fix (and so give it some more soak time to get right, but still okay for -rc1) rather than a feature addition (and therefore would need to be in a pull request today). Speak up now if this characterization is off base. > > Roman Kagan (7): > block/nbd: avoid touching freed connect_thread > block/nbd: use uniformly nbd_client_connecting_wait > block/nbd: assert attach/detach runs in the proper context > block/nbd: transfer reconnection stuff across aio_context switch > block/nbd: better document a case in nbd_co_establish_connection > block/nbd: decouple reconnect from drain > block/nbd: stop manipulating in_flight counter > > block/nbd.c | 191 +++++++++++++++++++++++---------------------------- > nbd/client.c | 2 - > 2 files changed, 86 insertions(+), 107 deletions(-) > -- Eric Blake, Principal Software Engineer Red Hat, Inc. +1-919-301-3226 Virtualization: qemu.org | libvirt.org