qdev: Don't leak string property value on hot unplug

parse_string() qemu_strdup()s the property value.  It is never freed.
It needs to be freed along with the device.  Otherwise, the value of
scsi-disk property "ver" gets leaked when hot-unplugging the disk, for
instance.

Call new PropertyInfo method free() from qdev_free().  Implement it
for qdev_prop_string.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

hw/qdev-properties.c

@@ -260,6 +260,11 @@ static int parse_string(DeviceState *dev, Property *prop, const char *str)
     return 0;
 }
 
+static void free_string(DeviceState *dev, Property *prop)
+{
+    qemu_free(*(char **)qdev_get_prop_ptr(dev, prop));
+}
+
 static int print_string(DeviceState *dev, Property *prop, char *dest, size_t len)
 {
     char **ptr = qdev_get_prop_ptr(dev, prop);
@@ -274,6 +279,7 @@ PropertyInfo qdev_prop_string = {
     .size  = sizeof(char*),
     .parse = parse_string,
     .print = print_string,
+    .free  = free_string,
 };
 
 /* --- drive --- */

hw/qdev.c

@@ -334,6 +334,7 @@ void qdev_init_nofail(DeviceState *dev)
 void qdev_free(DeviceState *dev)
 {
     BusState *bus;
+    Property *prop;
 
     if (dev->state == DEV_STATE_INITIALIZED) {
         while (dev->num_child_bus) {
@@ -349,6 +350,11 @@ void qdev_free(DeviceState *dev)
     }
     qemu_unregister_reset(qdev_reset, dev);
     QLIST_REMOVE(dev, sibling);
+    for (prop = dev->info->props; prop && prop->name; prop++) {
+        if (prop->info->free) {
+            prop->info->free(dev, prop);
+        }
+    }
     qemu_free(dev);
 }
 

hw/qdev.h

@@ -98,6 +98,7 @@ struct PropertyInfo {
     enum PropertyType type;
     int (*parse)(DeviceState *dev, Property *prop, const char *str);
     int (*print)(DeviceState *dev, Property *prop, char *dest, size_t len);
+    void (*free)(DeviceState *dev, Property *prop);
 };
 
 typedef struct GlobalProperty {