From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([209.51.188.92]:52875) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1goDjJ-0004oS-HF for qemu-devel@nongnu.org; Mon, 28 Jan 2019 15:42:06 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1goDck-0006rn-Om for qemu-devel@nongnu.org; Mon, 28 Jan 2019 15:35:19 -0500 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:42770 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 1goDck-0006rU-Ix for qemu-devel@nongnu.org; Mon, 28 Jan 2019 15:35:18 -0500 Received: from pps.filterd (m0098416.ppops.net [127.0.0.1]) by mx0b-001b2d01.pphosted.com (8.16.0.27/8.16.0.27) with SMTP id x0SKO3Qv056056 for ; Mon, 28 Jan 2019 15:35:17 -0500 Received: from e34.co.us.ibm.com (e34.co.us.ibm.com [32.97.110.152]) by mx0b-001b2d01.pphosted.com with ESMTP id 2qa817jghv-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Mon, 28 Jan 2019 15:35:17 -0500 Received: from localhost by e34.co.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Mon, 28 Jan 2019 20:35:16 -0000 References: <1545062250-7573-1-git-send-email-akrowiak@linux.ibm.com> From: Tony Krowiak Date: Mon, 28 Jan 2019 15:35:09 -0500 MIME-Version: 1.0 In-Reply-To: <1545062250-7573-1-git-send-email-akrowiak@linux.ibm.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Message-Id: Subject: Re: [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 On 12/17/18 10:57 AM, Tony Krowiak wrote: > 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; > } > > /* Just checking back on this one. Do we want to merge this patch and deal with the max_index issue in another patch, in this patch, or not at all? >