From nobody Mon Apr 29 03:43:01 2024 Delivered-To: importer@patchew.org Received-SPF: pass (zoho.com: domain of gnu.org designates 208.118.235.17 as permitted sender) client-ip=208.118.235.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Authentication-Results: mx.zohomail.com; spf=pass (zoho.com: domain of gnu.org designates 208.118.235.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org Return-Path: Received: from lists.gnu.org (lists.gnu.org [208.118.235.17]) by mx.zohomail.com with SMTPS id 1510327255567303.41537510423075; Fri, 10 Nov 2017 07:20:55 -0800 (PST) Received: from localhost ([::1]:42210 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1eDB6q-0007Ie-HY for importer@patchew.org; Fri, 10 Nov 2017 10:20:44 -0500 Received: from eggs.gnu.org ([2001:4830:134:3::10]:47097) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1eDB5r-0006qH-Nw for qemu-devel@nongnu.org; Fri, 10 Nov 2017 10:19:47 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1eDB5q-0003n3-O5 for qemu-devel@nongnu.org; Fri, 10 Nov 2017 10:19:43 -0500 Received: from mx1.redhat.com ([209.132.183.28]:41342) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1eDB5n-0003fD-I6; Fri, 10 Nov 2017 10:19:39 -0500 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 827F2C0467D5; Fri, 10 Nov 2017 15:19:38 +0000 (UTC) Received: from localhost (ovpn-117-183.ams2.redhat.com [10.36.117.183]) by smtp.corp.redhat.com (Postfix) with ESMTP id 339F565E86; Fri, 10 Nov 2017 15:19:35 +0000 (UTC) From: Stefan Hajnoczi To: Date: Fri, 10 Nov 2017 15:19:34 +0000 Message-Id: <20171110151934.16883-1-stefanha@redhat.com> 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 [10.5.110.31]); Fri, 10 Nov 2017 15:19:38 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 209.132.183.28 Subject: [Qemu-devel] [PATCH v4] throttle-groups: drain before detaching ThrottleState X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Kevin Wolf , Alberto Garcia , qemu-block@nongnu.org, Manos Pitsidianakis , Max Reitz , Stefan Hajnoczi Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail: RSF_0 Z_629925259 SPT_0 Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" I/O requests hang after stop/cont commands at least since QEMU 2.10.0 with -drive iops=3D100: (guest)$ dd if=3D/dev/zero of=3D/dev/vdb oflag=3Ddirect count=3D1000 (qemu) stop (qemu) cont ...I/O is stuck... This happens because blk_set_aio_context() detaches the ThrottleState while requests may still be in flight: if (tgm->throttle_state) { throttle_group_detach_aio_context(tgm); throttle_group_attach_aio_context(tgm, new_context); } This patch encloses the detach/attach calls in a drained region so no I/O request is left hanging. Also add assertions so we don't make the same mistake again in the future. Reported-by: Yongxue Hong Signed-off-by: Stefan Hajnoczi Reviewed-by: Alberto Garcia --- v4: * Simplified patch in response to Berto's review --- block/block-backend.c | 2 ++ block/throttle-groups.c | 6 ++++++ 2 files changed, 8 insertions(+) diff --git a/block/block-backend.c b/block/block-backend.c index 45d9101be3..da2f6c0f8a 100644 --- a/block/block-backend.c +++ b/block/block-backend.c @@ -1748,8 +1748,10 @@ void blk_set_aio_context(BlockBackend *blk, AioConte= xt *new_context) =20 if (bs) { if (tgm->throttle_state) { + bdrv_drained_begin(bs); throttle_group_detach_aio_context(tgm); throttle_group_attach_aio_context(tgm, new_context); + bdrv_drained_end(bs); } bdrv_set_aio_context(bs, new_context); } diff --git a/block/throttle-groups.c b/block/throttle-groups.c index b291a88481..2587f19ca3 100644 --- a/block/throttle-groups.c +++ b/block/throttle-groups.c @@ -594,6 +594,12 @@ void throttle_group_attach_aio_context(ThrottleGroupMe= mber *tgm, void throttle_group_detach_aio_context(ThrottleGroupMember *tgm) { ThrottleTimers *tt =3D &tgm->throttle_timers; + + /* Requests must have been drained */ + assert(tgm->pending_reqs[0] =3D=3D 0 && tgm->pending_reqs[1] =3D=3D 0); + assert(qemu_co_queue_empty(&tgm->throttled_reqs[0])); + assert(qemu_co_queue_empty(&tgm->throttled_reqs[1])); + throttle_timers_detach_aio_context(tt); tgm->aio_context =3D NULL; } --=20 2.13.6