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 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 smtp.lore.kernel.org (Postfix) with ESMTPS id 159B8C00140 for ; Fri, 5 Aug 2022 08:27:05 +0000 (UTC) Received: from localhost ([::1]:51492 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1oJsfg-0001K0-21 for qemu-devel@archiver.kernel.org; Fri, 05 Aug 2022 04:27:04 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:34658) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1oJsTX-0000qI-Sb for qemu-devel@nongnu.org; Fri, 05 Aug 2022 04:14:31 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:26856) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1oJsTV-0004Eh-Dt for qemu-devel@nongnu.org; Fri, 05 Aug 2022 04:14:31 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1659687268; 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=LQp5eZFwSI/xGMEy7umgYoeQSgji1LzJPsclcQD6Hw0=; b=Vrzg4bAhMylArF7ZisOGYurkIj6YKr1QHosDFMUuo67S1QJu4RoG6F3++EKIU3WXWFDYBJ 72cOHehABhdn7tiamfKPDybqW0NIfpaxH+2vP2zDrKwL+GjPHmuhjII3grYYFgvC+yYhh7 kZVbOlfivjMUqP0sNUpF7eRJhvBEwgo= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-672-ejOK058YPe-z3b2YpbmfiA-1; Fri, 05 Aug 2022 04:14:24 -0400 X-MC-Unique: ejOK058YPe-z3b2YpbmfiA-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.rdu2.redhat.com [10.11.54.3]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 4F922811E84; Fri, 5 Aug 2022 08:14:24 +0000 (UTC) Received: from redhat.com (unknown [10.39.193.127]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 096391121314; Fri, 5 Aug 2022 08:14:21 +0000 (UTC) Date: Fri, 5 Aug 2022 10:14:20 +0200 From: Kevin Wolf To: Emanuele Giuseppe Esposito Cc: qemu-block@nongnu.org, Hanna Reitz , Paolo Bonzini , John Snow , Vladimir Sementsov-Ogievskiy , Wen Congyang , Xie Changlong , Markus Armbruster , Stefan Hajnoczi , Fam Zheng , qemu-devel@nongnu.org, Vladimir Sementsov-Ogievskiy Subject: Re: [PATCH v10 12/21] commit and mirror: create new nodes using bdrv_get_aio_context, and not the job aiocontext Message-ID: References: <20220725073855.76049-1-eesposit@redhat.com> <20220725073855.76049-13-eesposit@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220725073855.76049-13-eesposit@redhat.com> X-Scanned-By: MIMEDefang 2.78 on 10.11.54.3 Received-SPF: pass client-ip=170.10.133.124; envelope-from=kwolf@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -21 X-Spam_score: -2.2 X-Spam_bar: -- X-Spam_report: (-2.2 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.082, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=unavailable 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: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Am 25.07.2022 um 09:38 hat Emanuele Giuseppe Esposito geschrieben: > We are always using the given bs AioContext, so there is no need > to take the job ones (which is identical anyways). > This also reduces the point we need to check when protecting > job.aio_context field. > > Reviewed-by: Vladimir Sementsov-Ogievskiy > Reviewed-by: Stefan Hajnoczi > Signed-off-by: Emanuele Giuseppe Esposito I'm not sure against which scenario this is actually protecting. The only reason for not using job.aio_context seems to be if someone else can change the job AioContext in parallel. However, if that is the case (I don't think it is, but for the hypothetical case this patch seems to address), the AioContext is not identical any more and the change is wrong because we actually want things to run in the job AioContext - otherwise accessing the BlockBackend from the job coroutine wouldn't be possible. So I believe the current code expresses how we actually want to use the BlockBackend and the change doesn't only protect nothing, but is even misleading because it implies that the job can work with any AioContext, which is not true. Kevin