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 49419C742A1 for ; Thu, 11 Jul 2019 19:58:37 +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 17501208E4 for ; Thu, 11 Jul 2019 19:58:37 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 17501208E4 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]:44958 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1hlfD9-0004W9-U8 for qemu-devel@archiver.kernel.org; Thu, 11 Jul 2019 15:58:35 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:51307) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1hlfCt-0003kK-G7 for qemu-devel@nongnu.org; Thu, 11 Jul 2019 15:58:20 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1hlfCr-0000lm-4U for qemu-devel@nongnu.org; Thu, 11 Jul 2019 15:58:19 -0400 Received: from mx1.redhat.com ([209.132.183.28]:23784) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1hlfCp-0000jn-Nn for qemu-devel@nongnu.org; Thu, 11 Jul 2019 15:58:16 -0400 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id AF3358762B; Thu, 11 Jul 2019 19:58:13 +0000 (UTC) Received: from localhost (unknown [10.40.205.198]) by smtp.corp.redhat.com (Postfix) with ESMTPS id EF2405DA65; Thu, 11 Jul 2019 19:58:10 +0000 (UTC) From: Max Reitz To: qemu-block@nongnu.org Date: Thu, 11 Jul 2019 21:58:00 +0200 Message-Id: <20190711195804.30703-2-mreitz@redhat.com> In-Reply-To: <20190711195804.30703-1-mreitz@redhat.com> References: <20190711195804.30703-1-mreitz@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.26]); Thu, 11 Jul 2019 19:58:13 +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] [RFC 1/5] block/nbd: Fix hang in .bdrv_close() 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 , qemu-devel@nongnu.org, Stefan Hajnoczi , Max Reitz Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" When nbd_close() is called from a coroutine, the connection_co never gets to run, and thus nbd_teardown_connection() hangs. This is because aio_co_enter() only puts the connection_co into the main coroutine's wake-up queue, so this main coroutine needs to yield and reschedule itself to let the connection_co run. Signed-off-by: Max Reitz --- block/nbd.c | 12 +++++++++++- 1 file changed, 11 insertions(+), 1 deletion(-) diff --git a/block/nbd.c b/block/nbd.c index 81edabbf35..b83b6cd43e 100644 --- a/block/nbd.c +++ b/block/nbd.c @@ -135,7 +135,17 @@ static void nbd_teardown_connection(BlockDriverState= *bs) qio_channel_shutdown(s->ioc, QIO_CHANNEL_SHUTDOWN_BOTH, NULL); - BDRV_POLL_WHILE(bs, s->connection_co); + + if (qemu_in_coroutine()) { + /* Let our caller poll and just yield until connection_co is don= e */ + while (s->connection_co) { + aio_co_schedule(qemu_get_current_aio_context(), + qemu_coroutine_self()); + qemu_coroutine_yield(); + } + } else { + BDRV_POLL_WHILE(bs, s->connection_co); + } =20 nbd_client_detach_aio_context(bs); object_unref(OBJECT(s->sioc)); --=20 2.21.0