From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:36396) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1gXoZw-0005UL-Jp for qemu-devel@nongnu.org; Fri, 14 Dec 2018 09:36:39 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1gXoZt-0007OO-6A for qemu-devel@nongnu.org; Fri, 14 Dec 2018 09:36:36 -0500 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:33408 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 1gXoZs-0007AS-Nv for qemu-devel@nongnu.org; Fri, 14 Dec 2018 09:36:32 -0500 Received: from pps.filterd (m0098417.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.22/8.16.0.22) with SMTP id wBEETEKS105335 for ; Fri, 14 Dec 2018 09:36:13 -0500 Received: from e35.co.us.ibm.com (e35.co.us.ibm.com [32.97.110.153]) by mx0a-001b2d01.pphosted.com with ESMTP id 2pccs6w8kq-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Fri, 14 Dec 2018 09:36:13 -0500 Received: from localhost by e35.co.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Fri, 14 Dec 2018 14:36:12 -0000 References: <1544718402-8703-1-git-send-email-akrowiak@linux.ibm.com> <20181214130953.53d3dd4d@oc2783563651> From: Tony Krowiak Date: Fri, 14 Dec 2018 09:36:08 -0500 MIME-Version: 1.0 In-Reply-To: <20181214130953.53d3dd4d@oc2783563651> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Message-Id: Subject: Re: [Qemu-devel] [PATCH v2] qdev/core: Can not replug device on bus that allows one device List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Halil Pasic Cc: qemu-devel@nongnu.org, mammedo@redhat.com On 12/14/18 7:09 AM, Halil Pasic wrote: > On Thu, 13 Dec 2018 11:26:42 -0500 > Tony Krowiak wrote: > >> If the maximum number of devices allowed on a bus is 1 and a device >> which is plugged into the bus is subsequently unplugged, attempting to replug >> the device fails with error "Bus 'xxx' does not support hotplugging". >> The "error" is detected in the qbus_is_full(BusState *bus) function >> (qdev_monitor.c) because bus->max_index >= bus_class->max_dev. The >> root of the problem is that the bus->max_index is not decremented when a device >> is unplugged from the bus. This patch fixes that problem. >> > > As Pierre has pointed out, the commit message is stale and inaccurate. > Subject could be better as well. I mean the problem is not limited to > buses that allow only one device. Each bus that can get full looses > capacity with every plug/unplug op pair. With that fixed: > > Reviewed-by: Halil Pasic I'll make the changes recommended by you and Pierre. > >> Signed-off-by: Tony Krowiak >> --- >> 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; >> } >> >> /* >