From nobody Tue Nov 4 21:40:44 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 1531238308456383.18203643429786; Tue, 10 Jul 2018 08:58:28 -0700 (PDT) Received: from localhost ([::1]:48539 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fcv23-0000vQ-DX for importer@patchew.org; Tue, 10 Jul 2018 11:58:27 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:46332) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fcuuf-0002sr-CR for qemu-devel@nongnu.org; Tue, 10 Jul 2018 11:50:50 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1fcuud-0005o2-Np for qemu-devel@nongnu.org; Tue, 10 Jul 2018 11:50:49 -0400 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:47990 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 1fcuud-0005l8-Hl for qemu-devel@nongnu.org; Tue, 10 Jul 2018 11:50:47 -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 8E7D0814F0B7; Tue, 10 Jul 2018 15:50:41 +0000 (UTC) Received: from localhost (ovpn-117-198.ams2.redhat.com [10.36.117.198]) by smtp.corp.redhat.com (Postfix) with ESMTP id 3D1182026D6B; Tue, 10 Jul 2018 15:50:41 +0000 (UTC) From: Stefan Hajnoczi To: Date: Tue, 10 Jul 2018 16:50:36 +0100 Message-Id: <20180710155037.16834-2-stefanha@redhat.com> In-Reply-To: <20180710155037.16834-1-stefanha@redhat.com> References: <20180710155037.16834-1-stefanha@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 [10.11.55.8]); Tue, 10 Jul 2018 15:50:41 +0000 (UTC) X-Greylist: inspected by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.8]); Tue, 10 Jul 2018 15:50:41 +0000 (UTC) for IP:'10.11.54.4' DOMAIN:'int-mx04.intmail.prod.int.rdu2.redhat.com' HELO:'smtp.corp.redhat.com' FROM:'stefanha@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] [PATCH 1/2] qdev: add HotplugHandler->post_plug() callback 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: l00284672 , Fam Zheng , "Michael S. Tsirkin" , Stefan Hajnoczi , Igor Mammedov , Paolo Bonzini 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" The ->pre_plug() callback is invoked before the device is realized. The ->plug() callback is invoked when the device is being realized but before it is reset. This patch adds a ->post_plug() callback which is invoked after the device has been reset. This callback is needed by HotplugHandlers that need to wait until after ->reset(). Signed-off-by: Stefan Hajnoczi Reviewed-by: Fam Zheng --- include/hw/hotplug.h | 12 ++++++++++++ hw/core/hotplug.c | 11 +++++++++++ hw/core/qdev.c | 7 +++++++ 3 files changed, 30 insertions(+) diff --git a/include/hw/hotplug.h b/include/hw/hotplug.h index 1a0516a479..1e8b1053b6 100644 --- a/include/hw/hotplug.h +++ b/include/hw/hotplug.h @@ -47,6 +47,8 @@ typedef void (*hotplug_fn)(HotplugHandler *plug_handler, * @parent: Opaque parent interface. * @pre_plug: pre plug callback called at start of device.realize(true) * @plug: plug callback called at end of device.realize(true). + * @post_plug: post plug callback called after device.realize(true) and de= vice + * reset * @unplug_request: unplug request callback. * Used as a means to initiate device unplug for devices = that * require asynchronous unplug handling. @@ -61,6 +63,7 @@ typedef struct HotplugHandlerClass { /* */ hotplug_fn pre_plug; hotplug_fn plug; + hotplug_fn post_plug; hotplug_fn unplug_request; hotplug_fn unplug; } HotplugHandlerClass; @@ -83,6 +86,15 @@ void hotplug_handler_pre_plug(HotplugHandler *plug_handl= er, DeviceState *plugged_dev, Error **errp); =20 +/** + * hotplug_handler_post_plug: + * + * Call #HotplugHandlerClass.post_plug callback of @plug_handler. + */ +void hotplug_handler_post_plug(HotplugHandler *plug_handler, + DeviceState *plugged_dev, + Error **errp); + /** * hotplug_handler_unplug_request: * diff --git a/hw/core/hotplug.c b/hw/core/hotplug.c index 17ac986685..ab34c19461 100644 --- a/hw/core/hotplug.c +++ b/hw/core/hotplug.c @@ -35,6 +35,17 @@ void hotplug_handler_plug(HotplugHandler *plug_handler, } } =20 +void hotplug_handler_post_plug(HotplugHandler *plug_handler, + DeviceState *plugged_dev, + Error **errp) +{ + HotplugHandlerClass *hdc =3D HOTPLUG_HANDLER_GET_CLASS(plug_handler); + + if (hdc->post_plug) { + hdc->post_plug(plug_handler, plugged_dev, errp); + } +} + void hotplug_handler_unplug_request(HotplugHandler *plug_handler, DeviceState *plugged_dev, Error **errp) diff --git a/hw/core/qdev.c b/hw/core/qdev.c index cf0db4b6da..78c0e031ff 100644 --- a/hw/core/qdev.c +++ b/hw/core/qdev.c @@ -865,6 +865,13 @@ static void device_set_realized(Object *obj, bool valu= e, Error **errp) } if (dev->hotplugged) { device_reset(dev); + + if (hotplug_ctrl) { + hotplug_handler_post_plug(hotplug_ctrl, dev, &local_err); + if (local_err !=3D NULL) { + goto child_realize_fail; + } + } } dev->pending_deleted_event =3D false; } else if (!value && dev->realized) { --=20 2.17.1 From nobody Tue Nov 4 21:40:44 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 (208.118.235.17 [208.118.235.17]) by mx.zohomail.com with SMTPS id 1531238488900226.10990575253936; Tue, 10 Jul 2018 09:01:28 -0700 (PDT) Received: from localhost ([::1]:48558 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fcv4p-0003fl-NP for importer@patchew.org; Tue, 10 Jul 2018 12:01:19 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:46355) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fcuug-0002tj-CZ for qemu-devel@nongnu.org; Tue, 10 Jul 2018 11:50:51 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1fcuuf-0005pY-IC for qemu-devel@nongnu.org; Tue, 10 Jul 2018 11:50:50 -0400 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:34678 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 1fcuuf-0005ml-Dd for qemu-devel@nongnu.org; Tue, 10 Jul 2018 11:50:49 -0400 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.rdu2.redhat.com [10.11.54.6]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 8342D402315B; Tue, 10 Jul 2018 15:50:43 +0000 (UTC) Received: from localhost (ovpn-117-198.ams2.redhat.com [10.36.117.198]) by smtp.corp.redhat.com (Postfix) with ESMTP id 105C82156889; Tue, 10 Jul 2018 15:50:42 +0000 (UTC) From: Stefan Hajnoczi To: Date: Tue, 10 Jul 2018 16:50:37 +0100 Message-Id: <20180710155037.16834-3-stefanha@redhat.com> In-Reply-To: <20180710155037.16834-1-stefanha@redhat.com> References: <20180710155037.16834-1-stefanha@redhat.com> X-Scanned-By: MIMEDefang 2.78 on 10.11.54.6 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.6]); Tue, 10 Jul 2018 15:50:43 +0000 (UTC) X-Greylist: inspected by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.6]); Tue, 10 Jul 2018 15:50:43 +0000 (UTC) for IP:'10.11.54.6' DOMAIN:'int-mx06.intmail.prod.int.rdu2.redhat.com' HELO:'smtp.corp.redhat.com' FROM:'stefanha@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] [PATCH 2/2] 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: l00284672 , Fam Zheng , "Michael S. Tsirkin" , Stefan Hajnoczi , Igor Mammedov , Paolo Bonzini 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" 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 Reviewed-by: Fam Zheng --- 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 3aa99717e2..1ec808e6fd 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, Error **errp) +{ + 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 2.17.1