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=-6.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS 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 AB5FEC31E46 for ; Wed, 12 Jun 2019 22:14:16 +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 82A5320896 for ; Wed, 12 Jun 2019 22:14:16 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 82A5320896 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]:35394 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1hbBVX-0001h2-Oj for qemu-devel@archiver.kernel.org; Wed, 12 Jun 2019 18:14:15 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:44706) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1hbBQR-0005lp-NB for qemu-devel@nongnu.org; Wed, 12 Jun 2019 18:09:01 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1hbBQP-0006Wd-MP for qemu-devel@nongnu.org; Wed, 12 Jun 2019 18:08:59 -0400 Received: from mx1.redhat.com ([209.132.183.28]:33360) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1hbBQK-0006Sh-CG; Wed, 12 Jun 2019 18:08:53 -0400 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 0B245307C945; Wed, 12 Jun 2019 22:08:44 +0000 (UTC) Received: from localhost (unknown [10.40.205.72]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 8CE4B61D09; Wed, 12 Jun 2019 22:08:43 +0000 (UTC) From: Max Reitz To: qemu-block@nongnu.org Date: Thu, 13 Jun 2019 00:08:38 +0200 Message-Id: <20190612220839.1374-2-mreitz@redhat.com> In-Reply-To: <20190612220839.1374-1-mreitz@redhat.com> References: <20190612220839.1374-1-mreitz@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.46]); Wed, 12 Jun 2019 22:08:44 +0000 (UTC) Content-Transfer-Encoding: quoted-printable X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.132.183.28 Subject: [Qemu-devel] [PATCH 1/2] vl: Drain before (block) job cancel when quitting 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 , Paolo Bonzini , qemu-devel@nongnu.org, Max Reitz Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" If the main loop cancels all block jobs while the block layer is not drained, this cancelling may not happen instantaneously. We can start a drained section before vm_shutdown(), which entails another bdrv_drain_all(); this nested bdrv_drain_all() will thus be a no-op, basically. We do not have to end the drained section, because we actually do not want any requests to happen from this point on. Signed-off-by: Max Reitz --- I don't know whether it actually makes sense to never end this drained section. It makes sense to me. Please correct me if I'm wrong. --- vl.c | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/vl.c b/vl.c index cd1fbc4cdc..3f8b3f74f5 100644 --- a/vl.c +++ b/vl.c @@ -4538,6 +4538,17 @@ int main(int argc, char **argv, char **envp) */ migration_shutdown(); =20 + /* + * We must cancel all block jobs while the block layer is drained, + * or cancelling will be affected by throttling and thus may block + * for an extended period of time. + * vm_shutdown() will bdrv_drain_all(), so we may as well include + * it in the drained section. + * We do not need to end this section, because we do not want any + * requests happening from here on anyway. + */ + bdrv_drain_all_begin(); + /* No more vcpu or device emulation activity beyond this point */ vm_shutdown(); =20 --=20 2.21.0