From 12b2e9f30f978f26f35f9df5c2ef96fbc019bab6 Mon Sep 17 00:00:00 2001 From: Tony Krowiak Date: Mon, 17 Dec 2018 10:57:30 -0500 Subject: qdev/core: fix qbus_is_full() 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 Message-Id: <1545062250-7573-1-git-send-email-akrowiak@linux.ibm.com> Reviewed-by: Igor Mammedov Signed-off-by: Eduardo Habkost --- qdev-monitor.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'qdev-monitor.c') diff --git a/qdev-monitor.c b/qdev-monitor.c index 07147c63bf..45a8ba4964 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; } /* -- cgit v1.2.3