[Qemu-stable] [PATCH v2] qdev: don't add typename to fw_dev_path when get_fw_dev_path isn't implemented

[Amos Kong]

Recent virtio refactoring in QEMU made virtio-bus become the parent bus
of scsi-bus, and virtio-bus doesn't have get_fw_dev_path implementation,
so redundant typename will be added to fw_dev_path. It causes that
bootindex parameter of scsi device doesn't work.

This patch changes qdev_get_fw_dev_path_helper() to add nothing if
implemented get_fw_dev_path() returns NULL.

Signed-off-by: Amos Kong <address@hidden>
--
v2: only add nothing to fw_dev_path when get_fw_dev_path() is
    implemented and return NULL. then it will not effect other devices
    don't have get_fw_dev_path() implementation.
---
 hw/core/qdev.c         | 5 +++++
 hw/virtio/virtio-bus.c | 6 ++++++
 2 files changed, 11 insertions(+)

diff --git a/hw/core/qdev.c b/hw/core/qdev.c
index 6985ad8..2a08368 100644
--- a/hw/core/qdev.c
+++ b/hw/core/qdev.c
@@ -509,11 +509,16 @@ static int qdev_get_fw_dev_path_helper(DeviceState *dev, 
char *p, int size)
 
     if (dev && dev->parent_bus) {
         char *d;
+        BusClass *parent_bc = BUS_GET_CLASS(dev->parent_bus);
+
         l = qdev_get_fw_dev_path_helper(dev->parent_bus->parent, p, size);
         d = bus_get_fw_dev_path(dev->parent_bus, dev);
+
         if (d) {
             l += snprintf(p + l, size - l, "%s", d);
             g_free(d);
+        } else if (parent_bc->get_fw_dev_path) {
+            return l;
         } else {
             l += snprintf(p + l, size - l, "%s", 
object_get_typename(OBJECT(dev)));
         }
diff --git a/hw/virtio/virtio-bus.c b/hw/virtio/virtio-bus.c
index ea2e11a..6849a01 100644
--- a/hw/virtio/virtio-bus.c
+++ b/hw/virtio/virtio-bus.c
@@ -161,10 +161,16 @@ static char *virtio_bus_get_dev_path(DeviceState *dev)
     return qdev_get_dev_path(proxy);
 }
 
+static char *virtio_bus_get_fw_dev_path(DeviceState *dev)
+{
+    return NULL;
+}
+
 static void virtio_bus_class_init(ObjectClass *klass, void *data)
 {
     BusClass *bus_class = BUS_CLASS(klass);
     bus_class->get_dev_path = virtio_bus_get_dev_path;
+    bus_class->get_fw_dev_path = virtio_bus_get_fw_dev_path;
 }
 
 static const TypeInfo virtio_bus_info = {
-- 
1.8.1.4