From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:50892) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1daXei-0002st-UE for qemu-devel@nongnu.org; Wed, 26 Jul 2017 21:32:02 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1daXed-00088a-W9 for qemu-devel@nongnu.org; Wed, 26 Jul 2017 21:32:00 -0400 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:40950 helo=mx0a-001b2d01.pphosted.com) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1daXed-00088D-Rh for qemu-devel@nongnu.org; Wed, 26 Jul 2017 21:31:55 -0400 Received: from pps.filterd (m0098419.ppops.net [127.0.0.1]) by mx0b-001b2d01.pphosted.com (8.16.0.21/8.16.0.21) with SMTP id v6R1Siqm049105 for ; Wed, 26 Jul 2017 21:31:55 -0400 Received: from e31.co.us.ibm.com (e31.co.us.ibm.com [32.97.110.149]) by mx0b-001b2d01.pphosted.com with ESMTP id 2bxyxvgmkg-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Wed, 26 Jul 2017 21:31:55 -0400 Received: from localhost by e31.co.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Wed, 26 Jul 2017 19:31:54 -0600 From: Michael Roth Date: Wed, 26 Jul 2017 20:30:55 -0500 In-Reply-To: <1501119055-4060-1-git-send-email-mdroth@linux.vnet.ibm.com> References: <1501119055-4060-1-git-send-email-mdroth@linux.vnet.ibm.com> Message-Id: <1501119055-4060-4-git-send-email-mdroth@linux.vnet.ibm.com> Subject: [Qemu-devel] [PATCH for-2.10 3/3] qdev: defer DEVICE_DEL event until instance_finalize() List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: peter.maydell@linaro.org, berrange@redhat.com, alex.williamson@redhat.com, pbonzini@redhat.com, david@gibson.dropbear.id.au, groug@kaod.org, armbru@redhat.com DEVICE_DEL is currently emitted when a Device is unparented, as opposed to when it is finalized. The main design motivation for this seems to be that after unparent()/unrealize(), the Device is no longer visible to the guest, and thus the operation is complete from the perspective of management. However, there are cases where remaining host-side cleanup is also pertinent to management. The is generally handled by treating these resources as aspects of the "backend", which can be managed via separate interfaces/events, such as blockdev_add/del, netdev_add/del, object_add/del, etc, but some devices do not have this level of compartmentalization, namely vfio-pci, and possibly to lend themselves well to it. In the case of vfio-pci, the "backend" cleanup happens as part of the finalization of the vfio-pci device itself, in particular the cleanup of the VFIO group FD. Failing to wait for this cleanup can result in tools like libvirt attempting to rebind the device to the host while it's still being used by VFIO, which can result in host crashes or other misbehavior depending on the host driver. Deferring DEVICE_DEL still affords us the ability to manage backends explicitly, while also addressing cases like vfio-pci's, so we implement that approach here. An alternative proposal involving having VFIO emit a separate event to denote completion of host-side cleanup was discussed, but the prevailing opinion seems to be that it is not worth the added complexity, and leaves the issue open for other Device implementations solve in the future. Signed-off-by: Michael Roth --- hw/core/qdev.c | 23 ++++++++++++----------- 1 file changed, 12 insertions(+), 11 deletions(-) diff --git a/hw/core/qdev.c b/hw/core/qdev.c index 08c4061..d14acba 100644 --- a/hw/core/qdev.c +++ b/hw/core/qdev.c @@ -1067,7 +1067,6 @@ static void device_finalize(Object *obj) NamedGPIOList *ngl, *next; DeviceState *dev = DEVICE(obj); - qemu_opts_del(dev->opts); QLIST_FOREACH_SAFE(ngl, &dev->gpios, node, next) { QLIST_REMOVE(ngl, node); @@ -1078,6 +1077,18 @@ static void device_finalize(Object *obj) * here */ } + + /* Only send event if the device had been completely realized */ + if (dev->pending_deleted_event) { + g_assert(dev->canonical_path); + + qapi_event_send_device_deleted(!!dev->id, dev->id, dev->canonical_path, + &error_abort); + g_free(dev->canonical_path); + dev->canonical_path = NULL; + } + + qemu_opts_del(dev->opts); } static void device_class_base_init(ObjectClass *class, void *data) @@ -1107,16 +1118,6 @@ static void device_unparent(Object *obj) object_unref(OBJECT(dev->parent_bus)); dev->parent_bus = NULL; } - - /* Only send event if the device had been completely realized */ - if (dev->pending_deleted_event) { - g_assert(dev->canonical_path); - - qapi_event_send_device_deleted(!!dev->id, dev->id, dev->canonical_path, - &error_abort); - g_free(dev->canonical_path); - dev->canonical_path = NULL; - } } static void device_class_init(ObjectClass *class, void *data) -- 2.7.4