From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:43344) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ff36Q-000167-Mk for qemu-devel@nongnu.org; Mon, 16 Jul 2018 08:59:47 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ff36P-00023J-NW for qemu-devel@nongnu.org; Mon, 16 Jul 2018 08:59:46 -0400 From: Thomas Huth Date: Mon, 16 Jul 2018 14:59:20 +0200 Message-Id: <1531745974-17187-4-git-send-email-thuth@redhat.com> In-Reply-To: <1531745974-17187-1-git-send-email-thuth@redhat.com> References: <1531745974-17187-1-git-send-email-thuth@redhat.com> Subject: [Qemu-devel] [PATCH v3 03/17] hw/arm/bcm2836: Fix crash with device_add bcm2837 on unsupported machines List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org, Peter Maydell , Paolo Bonzini Cc: qemu-arm@nongnu.org, Markus Armbruster , Eduardo Habkost , Beniamino Galvani , Subbaraya Sundeep , Alistair Francis , "Edgar E. Iglesias" , =?UTF-8?q?Andreas=20F=C3=A4rber?= When trying to "device_add bcm2837" on a machine that is not suitable for this device, you can quickly crash QEMU afterwards, e.g. with "info qtree": echo "{'execute':'qmp_capabilities'} {'execute':'device_add', " \ "'arguments':{'driver':'bcm2837'}} {'execute': 'human-monitor-command', " \ "'arguments': {'command-line': 'info qtree'}}" | \ aarch64-softmmu/qemu-system-aarch64 -M integratorcp,accel=qtest -S -qmp stdio {"QMP": {"version": {"qemu": {"micro": 50, "minor": 12, "major": 2}, "package": "build-all"}, "capabilities": []}} {"return": {}} {"error": {"class": "GenericError", "desc": "Device 'bcm2837' can not be hotplugged on this machine"}} Segmentation fault (core dumped) The qdev_set_parent_bus() from instance_init adds a link to the child devices which is not valid anymore after the bcm2837 instance has been destroyed. Unfortunately, the child devices do not get destroyed / unlinked correctly because both object_initialize() and object_property_add_child() increase the reference count of the child objects by one, but only one reference is dropped when the parent gets removed. So let's use the new functions object_initialize_child() and sysbus_init_child_obj() instead to create the objects, which will take care of creating the child objects with the correct reference count of one. Reviewed-by: Richard Henderson Reviewed-by: Paolo Bonzini Reviewed-by: Eduardo Habkost Signed-off-by: Thomas Huth --- hw/arm/bcm2836.c | 18 ++++++------------ 1 file changed, 6 insertions(+), 12 deletions(-) diff --git a/hw/arm/bcm2836.c b/hw/arm/bcm2836.c index 6805a7d..2595d93 100644 --- a/hw/arm/bcm2836.c +++ b/hw/arm/bcm2836.c @@ -51,25 +51,19 @@ static void bcm2836_init(Object *obj) int n; for (n = 0; n < BCM283X_NCPUS; n++) { - object_initialize(&s->cpus[n], sizeof(s->cpus[n]), - info->cpu_type); - object_property_add_child(obj, "cpu[*]", OBJECT(&s->cpus[n]), - &error_abort); + object_initialize_child(obj, "cpu[*]", &s->cpus[n], sizeof(s->cpus[n]), + info->cpu_type, &error_abort, NULL); } - object_initialize(&s->control, sizeof(s->control), TYPE_BCM2836_CONTROL); - object_property_add_child(obj, "control", OBJECT(&s->control), NULL); - qdev_set_parent_bus(DEVICE(&s->control), sysbus_get_default()); + sysbus_init_child_obj(obj, "control", &s->control, sizeof(s->control), + TYPE_BCM2836_CONTROL); - object_initialize(&s->peripherals, sizeof(s->peripherals), - TYPE_BCM2835_PERIPHERALS); - object_property_add_child(obj, "peripherals", OBJECT(&s->peripherals), - &error_abort); + sysbus_init_child_obj(obj, "peripherals", &s->peripherals, + sizeof(s->peripherals), TYPE_BCM2835_PERIPHERALS); object_property_add_alias(obj, "board-rev", OBJECT(&s->peripherals), "board-rev", &error_abort); object_property_add_alias(obj, "vcram-size", OBJECT(&s->peripherals), "vcram-size", &error_abort); - qdev_set_parent_bus(DEVICE(&s->peripherals), sysbus_get_default()); } static void bcm2836_realize(DeviceState *dev, Error **errp) -- 1.8.3.1