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qdev-monitor: Stop error avalanche in qbus_find_recursive()

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Reproducer:

    $ qemu-system-x86_64 -nodefaults -device virtio-rng-pci -device virtio-rng-pci -device virtio-rng-device,bus=virtio-bus
    qemu-system-x86_64: -device virtio-rng-device,bus=virtio-bus: Bus 'virtio-bus' is full
    qemu-system-x86_64: -device virtio-rng-device,bus=virtio-bus: Bus 'virtio-bus' is full
    qemu-system-x86_64: -device virtio-rng-device,bus=virtio-bus: Bus 'virtio-bus' not found

qbus_find_recursive() reports the "is full" error itself, and leaves
reporting "not found" to its caller.  The result is confusion.  Write
it a function contract that permits leaving all error reporting to the
caller, and implement it.  Update callers to detect and report "is
full".

Screwed up when commit 1395af6 added the max_dev limit and the "is
full" error condition to enforce it.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
This commit is contained in:
Markus Armbruster 2015-03-11 17:26:31 +01:00
parent d49190c420
commit a5ec494e27
1 changed files with 39 additions and 23 deletions
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62
qdev-monitor.c
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@ -364,43 +364,55 @@ static DeviceState *qbus_find_dev(BusState *bus, char *elem)
return NULL;
}
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;
}
/*
* Search the tree rooted at @bus for a bus.
* If @name, search for a bus with that name. Note that bus names
* need not be unique. Yes, that's screwed up.
* Else search for a bus that is a subtype of @bus_typename.
* If more than one exists, prefer one that can take another device.
* Return the bus if found, else %NULL.
*/
static BusState *qbus_find_recursive(BusState *bus, const char *name,
const char *bus_typename)
{
BusClass *bus_class = BUS_GET_CLASS(bus);
BusChild *kid;
BusState *child, *ret;
int match = 1;
BusState *pick, *child, *ret;
bool match;
if (name && (strcmp(bus->name, name) != 0)) {
match = 0;
} else if (bus_typename && !object_dynamic_cast(OBJECT(bus), bus_typename)) {
match = 0;
} else if ((bus_class->max_dev != 0) && (bus_class->max_dev <= bus->max_index)) {
if (name != NULL) {
/* bus was explicitly specified: return an error. */
qerror_report(ERROR_CLASS_GENERIC_ERROR, "Bus '%s' is full",
bus->name);
return NULL;
} else {
/* bus was not specified: try to find another one. */
match = 0;
}
assert(name || bus_typename);
if (name) {
match = !strcmp(bus->name, name);
} else {
match = !!object_dynamic_cast(OBJECT(bus), bus_typename);
}
if (match) {
return bus;
if (match && !qbus_is_full(bus)) {
return bus; /* root matches and isn't full */
}
pick = match ? bus : NULL;
QTAILQ_FOREACH(kid, &bus->children, sibling) {
DeviceState *dev = kid->child;
QLIST_FOREACH(child, &dev->child_bus, sibling) {
ret = qbus_find_recursive(child, name, bus_typename);
if (ret) {
return ret;
if (ret && !qbus_is_full(ret)) {
return ret; /* a descendant matches and isn't full */
}
if (ret && !pick) {
pick = ret;
}
}
}
return NULL;
/* root or a descendant matches, but is full */
return pick;
}
static BusState *qbus_find(const char *path)
@ -423,6 +435,10 @@ static BusState *qbus_find(const char *path)
if (!bus) {
qerror_report(QERR_BUS_NOT_FOUND, elem);
return NULL;
} else if (qbus_is_full(bus)) {
qerror_report(ERROR_CLASS_GENERIC_ERROR, "Bus '%s' is full",
elem);
return NULL;
}
pos = len;
}
@ -529,7 +545,7 @@ DeviceState *qdev_device_add(QemuOpts *opts)
}
} else if (dc->bus_type != NULL) {
bus = qbus_find_recursive(sysbus_get_default(), NULL, dc->bus_type);
if (!bus) {
if (!bus || qbus_is_full(bus)) {
qerror_report(ERROR_CLASS_GENERIC_ERROR,
"No '%s' bus found for device '%s'",
dc->bus_type, driver);