[PATCH] hw/core/qdev-clock: add a reference on aliased clocks

[Luc Michel]

When aliasing a clock with the qdev_alias_clock() function, a new link
property is created on the device aliasing the clock. The link points
to the aliased clock and use the OBJ_PROP_LINK_STRONG flag. This
property is read only since it does not provide a check callback for
modifications.

The object_property_add_link() documentation stats that with
OBJ_PROP_LINK_STRONG properties, the linked object reference count get
decremented when the property is deleted. But it is _not_ incremented on
creation (object_property_add_link() does not actually know the link).

This commit increments the reference count on the aliased clock to
ensure the aliased clock stays alive during the property lifetime, and
to avoid a double-free memory error when the property get deleted.

Signed-off-by: Luc Michel <luc@lmichel.fr>
---
 hw/core/qdev-clock.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/hw/core/qdev-clock.c b/hw/core/qdev-clock.c
index 6a9a340d0f..5f5e143702 100644
--- a/hw/core/qdev-clock.c
+++ b/hw/core/qdev-clock.c
@@ -59,10 +59,11 @@ static NamedClockList *qdev_init_clocklist(DeviceState 
*dev, const char *name,
     } else {
         object_property_add_link(OBJECT(dev), name,
                                  object_get_typename(OBJECT(clk)),
                                  (Object **) &ncl->clock,
                                  NULL, OBJ_PROP_LINK_STRONG);
+        object_ref(OBJECT(clk));
     }
 
     ncl->clock = clk;
 
     QLIST_INSERT_HEAD(&dev->clocks, ncl, node);
-- 
2.28.0