Commit be1ba4d5 authored by Peter Maydell's avatar Peter Maydell
Browse files

hw/core/bus.c: Only the main system bus can have no parent 



In commit 80376c3f in 2010 we added a workaround for
some qbus buses not being connected to qdev devices -- if the
bus has no parent object then we register a reset function which
resets the bus on system reset (and unregister it when the
bus is unparented).

Nearly a decade later, we have now no buses in the tree which
are created with non-NULL parents, so we can remove the
workaround and instead just assert that if the bus has a NULL
parent then it is the main system bus.

(The absence of other parentless buses was confirmed by
code inspection of all the callsites of qbus_create() and
qbus_create_inplace() and cross-checked by 'make check'.)

Signed-off-by: default avatarPeter Maydell <peter.maydell@linaro.org>
Reviewed-by: default avatarMarkus Armbruster <armbru@redhat.com>
Reviewed-by: default avatarPhilippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: default avatarDamien Hedde <damien.hedde@greensocs.com>
Tested-by: default avatarPhilippe Mathieu-Daudé <philmd@redhat.com>
Message-id: 20190523150543.22676-1-peter.maydell@linaro.org
parent 97fb318d

hw/core/bus.c

+9 −12
Original line number Diff line number Diff line
@@ -97,10 +97,9 @@ static void qbus_realize(BusState *bus, DeviceState *parent, const char *name) 
        bus->parent->num_child_bus++;

        object_property_add_child(OBJECT(bus->parent), bus->name, OBJECT(bus), NULL);

        object_unref(OBJECT(bus));

    } else if (bus != sysbus_get_default()) {

        /* TODO: once all bus devices are qdevified,

           only reset handler for main_system_bus should be registered here. */

        qemu_register_reset(qbus_reset_all_fn, bus);

    } else {

        /* The only bus without a parent is the main system bus */

        assert(bus == sysbus_get_default());

    }

}
@@ -109,18 +108,16 @@ static void bus_unparent(Object *obj) 
    BusState *bus = BUS(obj);

    BusChild *kid;



    /* Only the main system bus has no parent, and that bus is never freed */

    assert(bus->parent);



    while ((kid = QTAILQ_FIRST(&bus->children)) != NULL) {

        DeviceState *dev = kid->child;

        object_unparent(OBJECT(dev));

    }

    if (bus->parent) {

    QLIST_REMOVE(bus, sibling);

    bus->parent->num_child_bus--;

    bus->parent = NULL;

    } else {

        assert(bus != sysbus_get_default()); /* main_system_bus is never freed */

        qemu_unregister_reset(qbus_reset_all_fn, bus);

    }

}



void qbus_create_inplace(void *bus, size_t size, const char *typename,