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=-0.8 required=3.0 tests=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 DF03CC54EEB for ; Mon, 23 Mar 2020 18:15:05 +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 BA0912051A for ; Mon, 23 Mar 2020 18:15:05 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org BA0912051A Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=proxmox.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:38028 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jGRbM-0003Ix-Qh for qemu-devel@archiver.kernel.org; Mon, 23 Mar 2020 14:15:04 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:59564) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jGRaR-0002YL-Rv for qemu-devel@nongnu.org; Mon, 23 Mar 2020 14:14:08 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1jGRaQ-00062n-OP for qemu-devel@nongnu.org; Mon, 23 Mar 2020 14:14:07 -0400 Received: from proxmox-new.maurer-it.com ([212.186.127.180]:51927) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1jGRaQ-0005xy-HY for qemu-devel@nongnu.org; Mon, 23 Mar 2020 14:14:06 -0400 Received: from proxmox-new.maurer-it.com (localhost.localdomain [127.0.0.1]) by proxmox-new.maurer-it.com (Proxmox) with ESMTP id 6B84542887; Mon, 23 Mar 2020 19:13:54 +0100 (CET) Date: Mon, 23 Mar 2020 19:13:52 +0100 (CET) From: Dietmar Maurer To: Kevin Wolf Message-ID: <1825818863.138.1584987232460@webmail.proxmox.com> In-Reply-To: <20200323170710.GC8049@linux.fritz.box> References: <1577640273.5.1584605618249@webmail.proxmox.com> <20200323170710.GC8049@linux.fritz.box> Subject: Re: aio-context question MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Priority: 3 Importance: Normal X-Mailer: Open-Xchange Mailer v7.10.2-Rev22 X-Originating-Client: open-xchange-appsuite X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 212.186.127.180 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: , Reply-To: Dietmar Maurer Cc: "qemu-devel@nongnu.org" Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" > If it doesn't have any effect because it just does what will be done > later anyway, it can be removed, but that doesn't buy us much. I think that code is simply unnecessary (no effect). But it is quite hard to read and understand, so I think removing that code helps to simplify things. > If it results in preventing some case (like the one fixed by 30dd65f3), > we need to check whether this case is actually safe. If it is safe, we > can remove the lines and get a new feature from it. > > In both cases, I think a test case should be written together with the > removal of the code. And if we find out that it's unsafe, we should even > more write a test case that makes sure that the operation fails. Yes, a test case would be great. Especially one that test backups with io-threads. I am hunting a bug for more than a week now. Seems bdrv_drain hangs sometimes when running a backup job on drives using io-threads ... But I still haven't found a reliable way to reproduce it. Sometimes takes me several hours to trigger it again... I will try to write a test case if I can really find that bug...