From nobody Wed Nov 5 02:13:47 2025 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; dmarc=fail(p=none dis=none) header.from=redhat.com Return-Path: Received: from lists.gnu.org (lists.gnu.org [208.118.235.17]) by mx.zohomail.com with SMTPS id 1531840808372872.2749715130482; Tue, 17 Jul 2018 08:20:08 -0700 (PDT) Received: from localhost ([::1]:59931 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ffRlb-000701-0h for importer@patchew.org; Tue, 17 Jul 2018 11:19:55 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:48534) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ffRZQ-0005HA-FB for qemu-devel@nongnu.org; Tue, 17 Jul 2018 11:07:21 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ffRZK-0007IN-NR for qemu-devel@nongnu.org; Tue, 17 Jul 2018 11:07:20 -0400 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:47118 helo=mx1.redhat.com) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1ffRZK-0007I9-HL for qemu-devel@nongnu.org; Tue, 17 Jul 2018 11:07:14 -0400 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.rdu2.redhat.com [10.11.54.4]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 38C6E83221 for ; Tue, 17 Jul 2018 15:07:14 +0000 (UTC) Received: from 640k.localdomain.com (ovpn-112-17.ams2.redhat.com [10.36.112.17]) by smtp.corp.redhat.com (Postfix) with ESMTP id 145952026D68; Tue, 17 Jul 2018 15:07:12 +0000 (UTC) From: Paolo Bonzini To: qemu-devel@nongnu.org Date: Tue, 17 Jul 2018 17:06:51 +0200 Message-Id: <1531840015-28804-10-git-send-email-pbonzini@redhat.com> In-Reply-To: <1531840015-28804-1-git-send-email-pbonzini@redhat.com> References: <1531840015-28804-1-git-send-email-pbonzini@redhat.com> X-Scanned-By: MIMEDefang 2.78 on 10.11.54.4 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.1]); Tue, 17 Jul 2018 15:07:14 +0000 (UTC) X-Greylist: inspected by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.1]); Tue, 17 Jul 2018 15:07:14 +0000 (UTC) for IP:'10.11.54.4' DOMAIN:'int-mx04.intmail.prod.int.rdu2.redhat.com' HELO:'smtp.corp.redhat.com' FROM:'pbonzini@redhat.com' RCPT:'' X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 66.187.233.73 Subject: [Qemu-devel] [PULL 09/13] virtio-scsi: fix hotplug ->reset() vs event race 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: Fam Zheng , 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" From: Stefan Hajnoczi There is a race condition during hotplug when iothread is used. It occurs because virtio-scsi may be processing command queues in the iothread while the monitor performs SCSI device hotplug. When a SCSI device is hotplugged the HotplugHandler->plug() callback is invoked and virtio-scsi emits a rescan event to the guest. If the guest submits a SCSI command at this point then it may be cancelled before hotplug completes. This happens because ->reset() is called by hw/core/qdev.c:device_set_realized() after HotplugHandler->plug() has been called and hw/scsi/scsi-disk.c:scsi_disk_reset() purges all requests. This patch uses the new HotplugHandler->post_plug() callback to emit the rescan event after ->reset(). This eliminates the race conditions where requests could be cancelled. Reported-by: l00284672 Cc: Paolo Bonzini Cc: Fam Zheng Signed-off-by: Stefan Hajnoczi Message-Id: <20180716083732.3347-3-stefanha@redhat.com> Signed-off-by: Paolo Bonzini --- hw/scsi/virtio-scsi.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) diff --git a/hw/scsi/virtio-scsi.c b/hw/scsi/virtio-scsi.c index 3aa9971..5a3057d 100644 --- a/hw/scsi/virtio-scsi.c +++ b/hw/scsi/virtio-scsi.c @@ -797,8 +797,16 @@ static void virtio_scsi_hotplug(HotplugHandler *hotplu= g_dev, DeviceState *dev, virtio_scsi_acquire(s); blk_set_aio_context(sd->conf.blk, s->ctx); virtio_scsi_release(s); - } +} + +/* Announce the new device after it has been plugged */ +static void virtio_scsi_post_hotplug(HotplugHandler *hotplug_dev, + DeviceState *dev) +{ + VirtIODevice *vdev =3D VIRTIO_DEVICE(hotplug_dev); + VirtIOSCSI *s =3D VIRTIO_SCSI(vdev); + SCSIDevice *sd =3D SCSI_DEVICE(dev); =20 if (virtio_vdev_has_feature(vdev, VIRTIO_SCSI_F_HOTPLUG)) { virtio_scsi_acquire(s); @@ -968,6 +976,7 @@ static void virtio_scsi_class_init(ObjectClass *klass, = void *data) vdc->start_ioeventfd =3D virtio_scsi_dataplane_start; vdc->stop_ioeventfd =3D virtio_scsi_dataplane_stop; hc->plug =3D virtio_scsi_hotplug; + hc->post_plug =3D virtio_scsi_post_hotplug; hc->unplug =3D virtio_scsi_hotunplug; } =20 --=20 1.8.3.1