From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:42623) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1gYvH7-0004l6-0Z for qemu-devel@nongnu.org; Mon, 17 Dec 2018 10:57:47 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1gYvH2-00070T-2j for qemu-devel@nongnu.org; Mon, 17 Dec 2018 10:57:44 -0500 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:35638 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 1gYvH1-0006ze-TT for qemu-devel@nongnu.org; Mon, 17 Dec 2018 10:57:40 -0500 Received: from pps.filterd (m0098421.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.22/8.16.0.22) with SMTP id wBHFrVPl129197 for ; Mon, 17 Dec 2018 10:57:38 -0500 Received: from e11.ny.us.ibm.com (e11.ny.us.ibm.com [129.33.205.201]) by mx0a-001b2d01.pphosted.com with ESMTP id 2peee19h79-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Mon, 17 Dec 2018 10:57:38 -0500 Received: from localhost by e11.ny.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Mon, 17 Dec 2018 15:57:37 -0000 From: Tony Krowiak Date: Mon, 17 Dec 2018 10:57:30 -0500 Message-Id: <1545062250-7573-1-git-send-email-akrowiak@linux.ibm.com> Subject: [Qemu-devel] [PATCH v3] qdev/core: fix qbus_is_full() List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: pasic@linux.ibm.com, imammedo@redhat.com, pmorel@linux.ibm.com, Tony Krowiak The qbus_is_full(BusState *bus) function (qdev_monitor.c) compares the max_index value of the BusState structure with the max_dev value of the BusClass structure to determine whether the maximum number of children has been reached for the bus. The problem is, the max_index field of the BusState structure does not necessarily reflect the number of devices that have been plugged into the bus. Whenever a child device is plugged into the bus, the bus's max_index value is assigned to the child device and then incremented. If the child is subsequently unplugged, the value of the max_index does not change and no longer reflects the number of children. When the bus's max_index value reaches the maximum number of devices allowed for the bus (i.e., the max_dev field in the BusClass structure), attempts to plug another device will be rejected claiming that the bus is full -- even if the bus is actually empty. To resolve the problem, a new 'num_children' field is being added to the BusState structure to keep track of the number of children plugged into the bus. It will be incremented when a child is plugged, and decremented when a child is unplugged. Signed-off-by: Tony Krowiak Reviewed-by: Pierre Morel Reviewed-by: Halil Pasic --- hw/core/qdev.c | 3 +++ include/hw/qdev-core.h | 1 + qdev-monitor.c | 2 +- 3 files changed, 5 insertions(+), 1 deletion(-) diff --git a/hw/core/qdev.c b/hw/core/qdev.c index 6b3cc55b27c2..956923f33520 100644 --- a/hw/core/qdev.c +++ b/hw/core/qdev.c @@ -59,6 +59,8 @@ static void bus_remove_child(BusState *bus, DeviceState *child) snprintf(name, sizeof(name), "child[%d]", kid->index); QTAILQ_REMOVE(&bus->children, kid, sibling); + bus->num_children--; + /* This gives back ownership of kid->child back to us. */ object_property_del(OBJECT(bus), name, NULL); object_unref(OBJECT(kid->child)); @@ -73,6 +75,7 @@ static void bus_add_child(BusState *bus, DeviceState *child) char name[32]; BusChild *kid = g_malloc0(sizeof(*kid)); + bus->num_children++; kid->index = bus->max_index++; kid->child = child; object_ref(OBJECT(kid->child)); diff --git a/include/hw/qdev-core.h b/include/hw/qdev-core.h index a24d0dd566e3..521f0a947ead 100644 --- a/include/hw/qdev-core.h +++ b/include/hw/qdev-core.h @@ -206,6 +206,7 @@ struct BusState { HotplugHandler *hotplug_handler; int max_index; bool realized; + int num_children; QTAILQ_HEAD(ChildrenHead, BusChild) children; QLIST_ENTRY(BusState) sibling; }; diff --git a/qdev-monitor.c b/qdev-monitor.c index 07147c63bf8b..45a8ba49644c 100644 --- a/qdev-monitor.c +++ b/qdev-monitor.c @@ -414,7 +414,7 @@ static DeviceState *qbus_find_dev(BusState *bus, char *elem) static inline bool qbus_is_full(BusState *bus) { BusClass *bus_class = BUS_GET_CLASS(bus); - return bus_class->max_dev && bus->max_index >= bus_class->max_dev; + return bus_class->max_dev && bus->num_children >= bus_class->max_dev; } /* -- 2.7.4