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 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E0B9FC433F5 for ; Thu, 11 Nov 2021 17:54:21 +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 5F69B61354 for ; Thu, 11 Nov 2021 17:54:21 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 5F69B61354 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=nongnu.org Received: from localhost ([::1]:57424 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1mlEHE-00070e-8L for qemu-devel@archiver.kernel.org; Thu, 11 Nov 2021 12:54:20 -0500 Received: from eggs.gnu.org ([209.51.188.92]:52582) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mlEFk-0004yr-RY for qemu-devel@nongnu.org; Thu, 11 Nov 2021 12:52:48 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]:45374) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mlEFi-0002P5-6S for qemu-devel@nongnu.org; Thu, 11 Nov 2021 12:52:47 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1636653164; 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: in-reply-to:in-reply-to:references:references; bh=Xk8ulXZ6sER9mCRaB+/kR4JDK6Eowu1q1hnqfABn9EI=; b=MfbeEvDmrndg8RKfidpl6MdMWkosBpHOt8wLdk7/UVa6bbkUGhZuwIiXeVhIGph7lUUIfd jHZa2M+08Oy/pnBF6g38PHbGnf4wToLECexv8gMjKEWxHmDYIPCo/QZq5mXgPaQZIZqWh5 FIevZMEqOwv8yw0ADikIM6H3PMdULf0= 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-159-7hfsbSx_ODiEW7G8r-RBsw-1; Thu, 11 Nov 2021 12:52:43 -0500 X-MC-Unique: 7hfsbSx_ODiEW7G8r-RBsw-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id CF73D100F942; Thu, 11 Nov 2021 17:52:41 +0000 (UTC) Received: from redhat.com (unknown [10.39.193.238]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 31BA64180; Thu, 11 Nov 2021 17:52:31 +0000 (UTC) Date: Thu, 11 Nov 2021 18:52:30 +0100 From: Kevin Wolf To: Roman Kagan Subject: Re: [PATCH 01/10] vhost-user-blk: reconnect on any error during realize Message-ID: References: <20211111153354.18807-1-rvkagan@yandex-team.ru> <20211111153354.18807-2-rvkagan@yandex-team.ru> MIME-Version: 1.0 In-Reply-To: <20211111153354.18807-2-rvkagan@yandex-team.ru> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=kwolf@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Received-SPF: pass client-ip=170.10.129.124; envelope-from=kwolf@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -34 X-Spam_score: -3.5 X-Spam_bar: --- X-Spam_report: (-3.5 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.7, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H4=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: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: qemu-block@nongnu.org, "Michael S. Tsirkin" , qemu-devel@nongnu.org, Hanna Reitz , yc-core@yandex-team.ru, Paolo Bonzini , =?iso-8859-1?Q?Marc-Andr=E9?= Lureau Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Am 11.11.2021 um 16:33 hat Roman Kagan geschrieben: > vhost-user-blk realize only attempts to reconnect if the previous > connection attempt failed on "a problem with the connection and not an > error related to the content (which would fail again the same way in the > next attempt)". > > However this distinction is very subtle, and may be inadvertently broken > if the code changes somewhere deep down the stack and a new error gets > propagated up to here. > > OTOH now that the number of reconnection attempts is limited it seems > harmless to try reconnecting on any error. > > So relax the condition of whether to retry connecting to check for any > error. > > This patch amends a527e312b5 "vhost-user-blk: Implement reconnection > during realize". > > Signed-off-by: Roman Kagan It results in less than perfect error messages. With a modified export that just crashes qemu-storage-daemon during get_features, I get: qemu-system-x86_64: -device vhost-user-blk-pci,chardev=c: Failed to read msg header. Read 0 instead of 12. Original request 1. qemu-system-x86_64: -device vhost-user-blk-pci,chardev=c: Reconnecting after error: vhost_backend_init failed: Protocol error qemu-system-x86_64: -device vhost-user-blk-pci,chardev=c: Reconnecting after error: Failed to connect to '/tmp/vsock': Connection refused qemu-system-x86_64: -device vhost-user-blk-pci,chardev=c: Reconnecting after error: Failed to connect to '/tmp/vsock': Connection refused qemu-system-x86_64: -device vhost-user-blk-pci,chardev=c: Failed to connect to '/tmp/vsock': Connection refused I guess this might be tolerable. On the other hand, the patch doesn't really fix anything either, but just gets rid of possible subtleties. Kevin